Friday, November 29, 2019

A Voice of Her Own Kate Chopins Edna Pontellier free essay sample

How children, through play learn about their world and how this knowledge has been used. This paper shows the learning processes of young children through play and how a study of the results of this can be used in formal and informal educational settings. An overriding principle will be that play is both natural and important for children. Through play, children learn about their world. From the Paper: All these educators had some similarities. They all looked for ways to capitalize on the childs inherent nature and tendency to explore his world. They all recognized the young child as a concrete learner who learns best with hands-on activities.

Monday, November 25, 2019

Database Security Essay Example

Database Security Essay Example Database Security Essay Database Security Essay 1 Database Security *) GUNTHER PERNUL Institut fur Angewandte Informatik und Informationssysteme Abteilung fur Information Engineering Universitat Wien Vienna, Austria 1. Introduction 1. 1 The Relational Data Model Revisited 1. 2 The Vocabulary of Security and Major DB Security Threats 2. Database Security Models 2. 1 Discretionary Security Models 2. 2 Mandatory Security Models 2. 3 Adapted Mandatory Access Control Model 2. 4 Personal Knowledge Approach 2. 5 Clark and Wilson Model 2. 6 A Final Note on Database Security Models . Multilevel Secure Prototypes and Systems 3. 1 SeaView 3. 2 Lock Data Views 3. 3 ASD_Views 4. Conceptual Data Model for Multilevel Security 4. 1 Concepts of Security Semantics 4. 2 Classification Constraints 4. 3 Consistency and Conflict Management 4. 4 Modeling the Example Application 5. Standardization and Evaluation Efforts 6. Future Directions in Database Security Research 7. Conclusions References 1. Introduction Information stored in databases is often considered as a valuable and important corporate resource. Many organizations have become so dependent on the proper functioning of their systems that a disruption of service or a leakage of stored information may cause outcomes ranging from inconvenience to catastrophe. Corporate data may relate to financial records, others may be essential for the successful operation of an organization, may represent trade *) Advances in Computers, Vol. 38. M. C. Yovits (Ed. ), Academic Press, 1994, pp. 1 74. 2 secrets, or may describe information about persons whose privacy must be protected. Thus, the general concept of database security is very broad and entails such things as moral and ethical issues imposed by public and society, legal issues where control is legislated over the collection and disclosure of stored information, or more technical issues such as how to protect the stored information from loss or unauthorized access, destruction, use, modification, or disclosure. More generally speaking, database security is concerned with ensuring the secrecy, integrity, and availability of data stored in a database. To define the terms, secrecy denotes the protection of information from unauthorized disclosure either by direct retrieval or by indirect logical inference. In addition, secrecy must deal with the possibility that information may also be disclosed by legitimated users acting as an ‘information channel’ by passing secret information to unauthorized users. This may be done intentionally or without knowledge of the authorized user. Integrity requires data to be protected from malicious or accidental modification, including the insertion of false data, the contamination of data, and the destruction of data. Integrity constraints are rules that define the correct states of a database and thus can protect the correctness of the database during operation. Availability is the characteristic that ensures data being available to authorized users when they need them. Availability includes the ‘denial of service’ of a system, i. e. a system is not functioning in accordance with its intended purpose. Availability is closely related to integrity because ‘denial of service’ may be caused by unauthorized destruction, modification, or delay of service as well. Database security cannot be seen as an isolated problem because it is effected by other components of a computerized system as well. The security requirements of a system are specified by means of a security policy which is then enforced by various security mechanisms. For databases, requirements on the security can be classified into the following categories:  · Identification, Authentication Usually before getting access to a database each user has to identify himself to the computer system. Authentication is the way to verify the identity of a user at log-on time. Most common authentication methods are passwords but more advanced techniques like badge readers, biometric recognition techniques, or signature analysis devices are also available.  · Authorization, Access Controls Authorization is the specification of a set of rules that specify who has which type of access to what information. Authorization policies therefore govern the disclosure and modification of information. Access controls are 3 procedures that are designed to control authorizations. They are responsible to limit access to stored data to authorized users only.  · Integrity, Consistency An integrity policy states a set of rules (i. e. semantic integrity constraints) that define the correct states of the database during database operation and therefore can protect against malicious or accidental modification of information. Closely related issues to integrity and consistency are concurrency control and recovery. Concurrency control policies protect the integrity of the database in the presence of concurrent transactions. If these transactions do not terminate normally due to system crashes or security violations recovery techniques are used to reconstruct correct or valid database states.  · Auditing The requirement to keep records of all security relevant actions issued by a user is called auditing. Resulting audit records are the basis for further reviews and examinations in order to test the adequacy of system controls and to recommend any changes in the security policy. In this Chapter such a broad perspective of database security is not taken. Instead, main focus is directed towards aspects related to authorization and access controls. This is legitimate because identification, authentication, and auditing1 normally fall within the scope of the underlying operating system and integrity and consistency policies are subject to the closely related topic of ‘semantic data modeling’ or are dependent on the physical design of the DBMS software (namely, the transaction and recovery manager). Because most of the research in database security has concentrated on the relational data model, the discussion in this Chapter mostly concerns the framework of relational databases. However, the results described may generally be applicable to other database models as well. For an overall discussion on basic database security concepts consult the surveys by Jajodia and Sandhu (1990a), Lunt and Fernandez (1990), or Denning (1988). For references to further readings consult the annotated bibliography by Pernul and Luef (1992). The outline of this Chapter is as follows: In the remainder of the opening Section we shortly review the relational data model, we introduce a simple example that will be used throughout the Chapter, we present the basic terminology used in computer security, and we describe the most successful methods that might be used to penetrate a database. Because of the diversity of application domains for databases different security models and techniques 1. However, audit records are often stored and examined by using the DBMS software. 4 have been proposed so far. In Section 2 we review, evaluate, and compare the most prominent representatives among them. Section 3 contains an investigation of secure (trusted) database management systems (DBMSs). These are special purpose systems that support a level-based security policy and were designed and implemented with main focus on the enforcement of high security requirements. Section 4 focuses on one of the major problems level-based security related database research has to deal with. In this Section we address the problem of how to classify the data stored in the database with security classifications reflecting the security requirements of the application domain properly. What is necessary to counter this problem is to have a clear understanding of all the security semantics of the database application and a resulting clever database design. A semantic data/security model is proposed to arrive at a conceptualization and a clear understanding of the security semantics of the database application. Database security (and computer security in general) is subject to many national and international standardization efforts. The efforts have the goal to develop metrics to evaluate the degree of trust that can be placed in computer products used for the processing of sensitive information. In Section 5 we will briefly review these proposals. In Section 6 we will point out research challenges in database security and we will give our opinion of the direction in which we expect the entire field to move within the next few years. Finally, Section 7 will conclude this Chapter. 1. 1 The Relational Data Model Revisited The relational data model was invented by Codd (1970) and is described in most database textbooks. A relational database supports the relational data model and must have three basic principles: a set of relations, integrity rules, and a set of relational operators. Each relation consists of a state-invariant relation schema RS(A1, ,An), where each Ai is called attribute and defined over a domain dom(Ai). A relation R is a state-dependent instance of RS and consists of a set of distinct tuples of the form (a1, ,an), where each element ai must satisfy dom(Ai) (i. e. aiIdom(Ai)). Integrity constraints restrict the set of theoretically possible tuples (i. e. dom(A1) ? dom(A2) ? ? dom(An)) to the set of practically meaningful. Let X and Y denote sets of one or more of the attributes Ai in a relation schema. We say Y is functional dependent on X, written X ®Y, if and only if it is not possible to have two tuples with the same value for X but different values for Y. Functional dependencies represent the basis for most integrity constraints in the relation model of data. As not all possible relations are meaningful in an application, only those that satisfy certain integrity constraints are considered. 5 From the large set of proposed integrity constraints two are of major relevance for security: the key property and the referential integrity property. The key property states that each tuple must be uniquely identified by a key and a key attribute must not have the null-value. As a consequence each event of reality may be represented in the database only once. Referential integrity states that tuples referenced in one relation must exist in others and is expressed by means of foreign keys. These two rules are application independent and must be valid in each relational database. In addition many application dependent semantic constraints may exist in different databases. Virtual view relations (or shortly views) are distinguished from base relations. While the former are the result of relational operations and exists only virtually, the latter are actually present in the database and hold the stored data. Relational operations consist of the set operations, a select operation for selecting tuples from relations that satisfy a certain predicate, a project operation for projecting a relation on a subset of its attributes and a join operation for combining attributes and tuples from different relations. The relational data model was first implemented as System R by IBM and as INGRES at U. C. Berkeley. These two projects have mainly started and also considerably advanced the field of database security research. Both systems are the basis of most commercially available products. A few words on designing a database are in order. The design of a relational database is a complicated and difficult task and involves several phases and activities. Before the final relation schemas can be determined a careful requirements analysis and a conceptualization of the database is necessary. Usually this is done by using a conceptual data model which must be powerful enough to allow the modeling of all application relevant knowledge. The conceptual model is used as an intermediate representation of the database and finally transferred into corresponding relation schemas. It is very important to use a conceptual data model at this step because only such a high level data model allows to achieve a database that properly represents all of the application dependent data semantics. De facto standard for conceptual design is the Entity Relationship Approach (ER) (Chen, 1976) or one of its variants. In its graphical representation and in its simplest form the ER regards the world as consisting of a set of entity types (boxes), attributes (connected to boxes) and relationship types (diamonds). Relationship types are defined between entity types and are either of degree 1:1, 1:n, or n:m. The degree describes the maximum number of participating entities. Following is a short example of a relational database. This example will be used throughout the Chapter. It is very simple but sufficient to discuss many 6 ecurity relevant questions and to show the complexity of the field. Figure 1 contains the conceptualization of the database in form of an ER diagram and the corresponding relation schemas (key attributes are underlined, foreign keys are in italics). The database represents the fact that projects within an enterprise are carried out by employees. In this simple example we have to deal with the following three security objects: First, Employee represents a set of employees each of which is uniquely described by a characteristic SSN (i. e. the social security number). Of further interest are the Name, the Department the employee is working for, and the Salary of the employee. Second, Project is a set of projects carried out by the enterprise. Each project has an identifying Title, a Subject, and a Client. Finally, security object Assignment contains the assignments of employees to projects. Each assignment is characterized by the Date of the assignment and the Function the employee has to perform during the participation in the project. A single employee can be assigned to more than one project and a project may be carried out by more than one employee. 1. The Vocabulary of Security and Major DB Security Threats Before presenting the details of database security research it is necessary to define the terminology used and the potential threats to database security. As already has been pointed out, security requirements are stated by means of a security policy which consists of a set of laws, rules and practices that regulate how an organization man ages, protects, and distributes sensitive information. In general, a security policy is stated in terms of a set of security objects and a set of security subjects. A security object is a passive entity that contains or receives information. This might be a structured concept like a whole database, Employee Project Assignment N M Date Function SSN Title Title Subject Client SSN Name Dep Salary Employee (SSN, Name, Dep, Salary) Project (Title, Subject, Client) Assignment (Title, SSN, Date, Function) FIG. 1. Representations of the Example DB 7 a relation, a view, a tuple, an attribute, an attribute value, or even a fact of reality which is represented in the database. A security object might also be unstructured like a physical memory segment, a byte, a bit, or even a physical device like a printer or a processor. Please note, the term object is used differently in other computer science disciplines. Within the framework presented here, security objects are the target of protection. A security subject is an active entity, often in the form of a person (user) or process operating on behalf of a user. Security subjects are responsible for a change of a database state and cause information to flow within different objects and subjects. Most sources of threats to database security come from outside the computing system. If most emphasis is given to authorization, the users and processes operating on behalf of the users must be subject to security control. An active database process may be operating on behalf of an authorized user who has legitimate access or may be active on behalf of a person who succeeded in penetrating the system. In addition, an authorized database user may act as an ‘information channel’ by passing restricted information to unauthorized users. This may be intentionally or without knowledge of the authorized user. Some of the most successful database penetration methods are:  · Misuses of authority Improper acquisition of resources, theft of programs or storage media, modification or destruction of data. Logical Inference and Aggregation Both deal with users authorized to use the database. Logical inference arises whenever sensitive information can be inferred from combining less sensitive data. This may also involve certain knowledge from outside the database system. Tightly related to logical inference is the aggregation problem, wherein individual data items are not sensitive but a large enough c ollection of individual values taken together is considered sensitive.  · Masquerade A penatrator may gain unauthorized access by masquerading as a different person.  · Bypassing Controls This might be password attacks and exploitation of system trapdoors that avoid intended access control mechanisms. Trapdoors are security flaws that were built in the source code of a program by the original programmer.  · Browsing A penetrator circumvents the protection and searches directory or 8 dictionary information, trying to locate privileged information. Unless strict need-to-know access controls are implemented the browsing problem is a major flaw of database security.  · Trojan Horses A Trojan horse is hidden software that tricks a legitimate user without his knowledge to perform certain actions he is not aware of. For example, a Trojan Horse may be hidden into a sort routine and be designed to release certain data to unauthorized users. Whenever a user activates the sort routine, for example for sorting the result of a database query, the Trojan horse will act with the users identity and thus will have all privileges of the user.  · Covert Channels Usually information stored in a database is retrieved by means of legitimate information channels. In contrast to legitimate channels covert channels are paths that are not normally intended for information transfer. Such hidden paths may either be storage channels like shared memory or temporary files that could be used for communication purposes or timing channels like a degradation of overall system performance.  · Hardware, Media Attacks Physical attacks on equipment and storage media. The attack scenario described above is not restricted to occur in databases only. For example, the German Chaos Computer Club succeeded in attacking a NASA system masqueraded, by bypassing access controls (by means of an operating system flaw) and Trojan horses to capture passwords. As reported by Stoll (1988) some of these techniques were also used by the Wily Hacker. The Internet worm in 1988 exploited trapdoors in electronic mail handling systems and infected more than 5000 machines connected to the Internet network (Rochlis and Eichin, 1989). Thompson (1984), in his Turing Award Lecture, demonstrated a Trojan horse placed in the executable form of a compiler that permitted the insertion of a trapdoor in each program compiled with the compiler. It is generally agreed that the number of the known cases of computer abuse is significantly smaller than the cases actually happened because in this topic a large number of dark figures exist. 2. Database Security Models 9 Because of the diversity of the application domains for databases different security models and techniques have been proposed to counter the various threats against the security. In this Section we will discuss the most prominent among them. In a nutshell, Discretionary Security specifies the rules under which subjects can, at their discretion, create and delete objects, and grant and revoke authorizations for accessing objects to others. In addition to controlling the access Mandatory Security regulates the flow of information between objects and subjects. Mandatory security controls are very effective but suffer from several drawbacks. One attempt to overcome certain limitations of mandatory protection systems is the Adapted Mandatory Access Control (AMAC) model, a security technique that focuses on the design aspect of secure databases. The Personal Knowledge Approach is concentrating on enforcing the basic law of many countries for the informational selfdetermination of humans and the Clark and Wilson Model tries to represent common commercial business practice in a computerized security model. First attempts to compare some of these techniques have been made by Biskup (1990) and Pernul and Tjoa (1992). Landwehr (1981) is a very good survey of formal policies for computer security in general and Millen (1989) focuses on various aspects of mandatory computer security. 2. 1 Discretionary Security Models Discretionary security models are fundamental to operating systems and DBMSs and have now been studied for a long time. From 1970 through 1975, there was a good deal of interest in the theoretical aspects of these models. Then most of the relational database security research has turned to other security techniques. However, the appearance of more advanced data models has renewed interest in discretionary policies. 2. 1. 1 Discretionary Access Controls Discretionary access controls (DAC) are based on the concepts of a set of security objects O, a set of security subjects S, a set of access privileges T defining what kind of access a subject has to a certain object, and in order to represent content-based access rules a set of predicates P. Applied to relational databases O is a finite set of values {o1, ,on} representing relation schemas, S is a finite set of potential subjects {s1, sm} representing users, groups of them, or transactions operating on behalf of users. Access types (privileges) are the set of database operations such as select, insert, delete, update, execute, grant, or 10 revoke and predicate pIP defines the access window of subject sIS on object oIO. The tuple o,s,t,p is called access rule and a function f is defined to determine if an authorization f(o,s,t,p) is valid or not: : O ? S ? T ? P  ® {True, False}. For any o,s,t,p, if f(o,s,t,p) evaluates into True, subject s has authorization t to access object o within the range defined by predicate p. An important property of discretionary security models is the support of the principle of delegation of rights where a right is the (o,t,p)-portion of the access rule. A subject si who holds the right (o,t,p) may be allowed to delegate that right to ano ther subject sj (i? j). Most systems supporting DAC store access rules in an access control matrix. In its simplest form the rows of the matrix represent subjects, the columns represent the objects and the intersection of a row and a column contains the access type that subject has authorization for with respect to the object. The access matrix model as a basis for discretionary access controls was formulated by Lampson (1971) and subsequently refined by Graham and Denning (1972), and by Harrison et al. (1976). A more detailed discussion on discretionary controls in databases may be found in the book by Fernandez et al. (1981). Discretionary security is enforced in most commercial DBMS products and is based on the concept of database views. Instead of authorizing a user to the base relations of a system the information of the access control matrix is used to restrict the user to a particular subset of the data available. Two main system architectures for view-based protection can be identified: query modification and view relations. Query modification is implemented in Ingres-style DBMSs (Stonebraker and Rubinstein 1976) and consists of appending additional security relevant qualifiers to a user supplied query. View relations are unmaterialized queries which are based on physical base relations. Instead of authorizing the users to base relations they have access to the virtual view relations only. By means of qualifiers in the view definition security restrictions can be implemented. View relations are the underlying protection mechanism of System R-based DBMSs (Griffiths and Wade, 1976). 2. 1. 2 DAC-based Structural Limitations Although very common discretionary models suffer from major drawbacks when pplied to databases with security critical content. In particular we see the following limitations:  · Enforcement of the security policy 11 DAC is based on the concept of ownership of information. In contrast to enterprise models, where the whole enterprise is the ‘owner’ of information and responsible for granting access to stored data, DAC systems assign the ownership of information to the creator of the data items in the database and allow the creator subject to grant acc ess to other users. This has the disadvantage that the burden of enforcing the security requirements of the enterprise is in the responsibility of the users themselves and cannot be controlled by the enterprise without involving high costs.  · Cascading authorization If two or more subjects have the privilege of granting or revoking certain access rules to other subjects this may lead to cascading revocation chains. As an example consider subjects s1, s2, s3, and access rule (s1,o,t,p). Subject s2 receives the privilege (o,t,p) from s1 and grants this access rule to s3. Later, s1 grants (o,t,p) again to s3 but s2 revokes (o,t,p) from s3 because of some reason. The effect of these operations is that s3 still has the authorization (from s1) to access object o by satisfying predicate p and using privilege t even if subject s2 has revoked it. This has the consequence that subject s2 is not aware of the fact that authorization (s3,o,t,p) is still in effect.  · Trojan Horse attacks In systems supporting DAC the identity of the subjects is crucial, and if actions can be performed using another subject’s identity, then DAC can be subverted. A Trojan Horse can be used to grant a certain right (o,t,p) of subject si on to sj (i? j) without the knowledge of subject si. Any program which runs on behalf of a subject acts with the identity of the subject and therefore has all of the DAC access rights of the subject’s processes. If a program contains a Trojan Horse with the functionality of granting access rules on to other users this cannot be restricted by discretionary access control methods.  · Update problems View-based protection results in unmaterialized queries which have no explicit physical representation in the database. This has the advantage of being very flexible to support the subjects with different views and to automatically filter out data a subject is not authorized to access but has the disadvantage that not all data is updateable through certain views. This is due to integrity reasons that might be violated in data not contained in the view by updating data from the view. 2. 2 Mandatory Security Models 12 Mandatory policies address a higher level of threat than discretionary policies because in addition to controlling the access to data they control the flow of data as well. Moreover, mandatory security techniques overcome the structural limitations of DAC-based protection as described above. 2. 2. 1 Mandatory Access Controls While discretionary models are concerned with defining, modeling, and enforcing access to information mandatory security models are in addition concerned with the flow of information within a system. Mandatory security requires that security objects and subjects are assigned to certain security levels represented by a label. The label for an object o is called its classification (class(o)) and a label for a subject s is called its clearance (clear(s)). The classification represents the sensitivity of the labeled data while the clearance of a subject its trustworthiness to not disclose sensitive information to others. A security label consists of two components: a level from a hierarchical list of sensitivity levels or access classes (for example: top_secret secret confidential unclassified) and a member of a non hierarchical set of categories, representing classes of object types of the universe of discourse. Clearance and classification levels are totally ordered resulting security labels are only partially ordered thus, the set of classifications forms a lattice. In this lattice security class c1 is comparable to and dominates (? ) c2 if the sensitivity level of c1 is greater than or equal to that of c2 and the categories in c1 contain those in c2. Mandatory security grew out of the military environment where it is practice to label information. However, this custom is also common in many companies and organizations where labels termed like ‘confidential’ or ‘company confidential’ are used. Mandatory access control (MAC) requirements are often stated based on Bell and LaPadula (1976) and formalized by two rules. The first (simple property) protects the information of the database from unauthorized disclosure, and the second (*-property) protects data from contamination or unauthorized modification by restricting the information flow from high to low. (1) Subject s is allowed to read data item d if clear(s) ? class(d). (2) Subject s is allowed to write data item d if clear(s) ? class(d). Few final sentences on MAC policies are in order. In many discussions confusion has arisen about the fact that in mandatory systems it is not only sufficient to have strong controls over who can read which data. Why is it necessary to include strong controls over who can write which data in systems with high security requirements? The reason is that a system with high security 13 needs must protect itself against attacks from unauthorized as well as from authorized users. There are several ways authorized users may disclose sensitive information to others. This can be done by mistake, as a deliberate illegal action, or the user may be tricked to do so by a Trojan horse attack. The simplest technique to disclose information by an authorized user is to retrieve it from the database, to copy it into an ‘owned’ object, and to make the copy available to others. To prevent from doing so, it is necessary to control the ability of the authorized user to make a copy (which implies the writing of data). In particular, once a transaction has successfully completed a read attempt, the protection system must ensure that there is no write to a lower security level (write-down) that is caused by a user authorized to execute a read transaction. As the read and write checks are both mandatory controls, a MAC system successfully protects against the attempt to copy information and to grant the copy to unauthorized users. By not allowing higher classified subjects to ‘write-down’ on lower classified data information flow among subjects with different clearances can efficiently be controlled. As covert storage channels require writing to objects the *-property also helps to limit leakage of information by these hidden paths. Mandatory integrity policies have also been studied. Biba (1977) has formulated an exact mathematical dual of the Bell-LaPadula model, with integrity labels and two properties: no-write-up in integrity and no-read-down in integrity. That is, low integrity objects (including subjects) are not permitted to contaminate higher integrity objects, or in other words no resource is permitted to depend upon other resources unless the latter are at least as trustworthy as the former. As an interesting optional feature mandatory security and the Bell- LaPadula (BLP) paradigm may lead to multilevel databases. These are databases containing relations which may appear different to users with different clearances. This is due to the following two reasons: Firstly, not all clearances may authorize all subjects to all data and secondly, the support of MAC may lead to polyinstantiation of attributes or tuples. We will discuss polyinstantiation and the mandatory relational data model in more detail in the next Subsection. 2. 2. 2 The Multilevel Secure Relational Data Model In this Subsection we will define the basic components of the multilevel secure (MLS) relational data model. We will consider the most general case in which an individual attribute value is subject to security label assignment. We will start by using the example database scenario from the Introduction. 14 Throughout the text, whenever we refer to the example we assume the existence of four sensitivity levels, denoted by TS, S, Co, U (where TSSCoU) and a single category only. In each relational schema TC is an additional attribute and contains the tuple classification. Consider the three different instances of relation Project as given in Figure 2. Fig. 2(a) corresponds to the view of a subject s with clear(s) = S. Because of the simple property of BLP (read access rule) users cleared at U would see the instances of Project as shown in Fig. 2(b). In this case the simple property of BLP would automatically filter out data that dominate U. Consider further a subject s with clear (s) = U and an insert operation where the user wishes to insert the tuple Alpha, Production, D into the relation shown in Fig. 2(b). Because of the key integrity property a standard relational DBMS would not allow this operation (Although not seen by user s Alpha as a key already exists in relation Project. ). However, from a security point of view the insert must not be rejected because otherwise a covert signalling channel occurs from which s may conclude that sensitive information he is not authorized to access may exist. The outcome of the operation is shown in Fig. 2 (c) and consists of a polyinstantiated tuple in MLS relation Project. A similar situation may occur if a subject cleared for the U-level would update Beta, null, null in Project as shown in Fig. 2(b) by replacing the null-values with certain data items. Again, this would lead to polyinstantiation in relation Project. As another example of FIG. 2. Instances of MLS Relation ‘Project’ (b) Project U Title Subject Client TC Beta, U -, U -, U U Celsius, U Production, U C, U U (a) Project S Title Subject Client TC Alpha, S Development, S A, S S Beta, U Research, S B, S S Celsius, U Production, U C, U U (c) Polyinstantiation at the tuple level Title Subject Client TC Alpha, S Development, S A, S S Beta, U Research, S B, S S Celsius, U Production, U C, U U Alpha, U Production, U D, U U 15 polyinstantiation consider that subject s with clear(s)=S wants to update Celsius, Production, C. In systems supporting MAC such an update is not allowed because of the *-property of BLP. This is necessary because an undesired information flow might occur between subjects cleared at the S-level to subjects cleared at the U-level. Thus, if a S-level subject wishes to update the tuple the update again must result into polyinstantiation. The problem of polyinstantiation arises because of the avoidance of a covert channel. Lampson (1973) has defined a covert channel as a means of downward information flow. As example let us consider the situation described above once more. If an insert operation is rejected to a subject because of the presence of a tuple at a higher level, the subject might be able to infer the existence of that tuple, resulting in a downward information flow. With respect to security much more may happen than just inferring the presence of a tuple. The success or failure of the service request, for example, can be used repeatedly to communicate one bit of information (0: failure, 1: success) to the lower level. Therefore, the problem is not only the inferring of a classified tuple, moreover, any information visible at the higher level can be sent through a covert channel to the lower level. The theory of most data models is built around the concept, that a fact of reality is represented in the database only once. Because of polyinstantiation this fundamental property is no longer true for MLS databases thus making the development of a new theory necessary. The state of development of a MLS relational theory has been considerably advanced by the researchers involved in the SeaView project. For example, see Denning et al. (1988) or Lunt et al. (1990). The following discussion of the theoretical concepts behind the MLS relational data model is mainly based on the model developed by Jajodia and Sandhu (1991a). In the Jajodia-Sandhu model each MLS relation consists of a state-invariant multilevel relation schema RS (A1, C1, , An, Cn, TC), where each Ai is an attribute defined over a domain dom(Ai), each Ci is classification for Ai and TC is the tuple-class. The domain of Ci is defined by [Li, Hi] which is a sublattice of all security labels. The resulting domain of TC is [lub {Li, i=1.. n}, lub {Hi, i=1.. n}], where lub denotes least upper bound operation in the sublattice of security labels. In the Jajodia-Sandhu model TC is included but is an unnecessary attribute. A multilevel relation schema corresponds to a collection of state-dependent relation instances R, one for each access class c. A relation instance is denoted by Rc (A1, C1, An, Cn, TC) and consists of a set of distinct tuples of the form (a1, c1, , an, cn, tc) where each ai I dom (Ai), c ? ci, ci I [Li, Hi], and tc = lub 16 {ci, i=1.. n}. We use the notion t[Ai] to refer to the value of attribute Ai in tuple t while t[Ci] denotes the classification of Ai in tuple t. Because of the simpleproperty of BLP, t[Ai] is visible for subjects with clear(s) ? [Ci]; otherwise t[Ai] is replaced with the null-value. The standard relational model is based on two core integrity properties: the key property and the referential integrity property. In order to meet the requirements for MLS databases both have been adapted and two further properties have been introduced. In the standard relational data model a key is derived by using the concept of functional dependencies. In the MLS relational mode l such a key is called apparent key. Its notion has been defined by Jajodia et al. (1990). For the following we assume RS (A1, C1, An, Cn, TC) being a MLS relation schema and A (AI{A1, , An}) the attribute set forming its apparent key. [MLS Integrity property 1]: Entity Integrity. A MLS relation R satisfies entity integrity if and only if for all instances Rc and t I Rc 1. Ai I A ? t[Ai] ? null 2. Ai, Aj I A ? t[Ci] = t[Cj] 3. Ai I A ? t[Ci] ? t[CA] (CA is classification of key A) Entity integrity states that the apparent key may not have the null value, must be uniformly classified and its classification must be dominated by all classifications of the other attributes. [MLS Integrity property 2]: Null Integrity. R satisfies null integrity if and only if for each Rc of R the following conditions hold: 1. For every tIRc, t[Ai]=null ? t[Ci] = t[CA] 2. Rc is subsumtion free, i. e. does not contain two distinct tuples such that one subsumes the other. A tuple t subsumes a tuple s, if for every attribute Ai, either t[Ai, Ci] = s[Ai, Ci] or t[Ai] ? null and s[Ai] = null. Null integrity states that null values must be classified at the level of the key and that for subjects cleared for the higher security classes, the null values visible for the lower clearances are replaced by the proper values automatically. The next property deals with consistency between the different instances Rc of R. The inter-instance property was first defined by Denning et al. (1988) within the SeaView framework, later corrected by Jajodia and Sandhu (1990b) and later again included in SeaView by Lunt et al. (1990). [MLS Integrity property 3]: Inter-instance Integrity. R satisfies the interinstance integrity if for all instances Rc of R and all c’ c a filter function s produces Rc’. In this case Rc’ = s(Rc, c’) must satisfy the following conditions: 17 1. For every t I Rc such that t[CA] ? c’ there must be a tuple t’ I Rc’ 2. There are no additional tuples in Rc’ other than those derived by the above rule. Rc’ is made subsumtion free. The inter-instance property is concerned with consistency between relation instances of a multilevel relation R. The filter function s maps R to different instances Rc (one for each c’c). By using filtering a user may be restricted to that portion of the multilevel relation for which the user is cleared. If c’ dominates some security levels in a tuple but not others, then during query processing the filter function s replaces all attribute values the user is not cleared to see by null-values. Because of the use of this filter function a shortcoming in the Jajodia-Sandhu model has been pointed out by Smith and Winslett (1992). Smith and Winslett state that s introduces an additional semantics for nulls. In the Jajodia-Sandhu model a null value can now mean ‘information available but hidden’ and this null value cannot be distinguished from a null-value representing the semantics ‘value exists but not known’ or a null-value with the meaning ‘this property will never have a value’. In a database all kinds of nulls may be present nd at a certain security level it may be hard for the subjects to say what should be believed at that level. Let us now draw our attention to polyinstantiation. As we have seen in the example given above polyinstantiation may occur on several different occasions. For example, because of a user with low clearance trying to insert a tuple that already exists with higher classification, because of a user wanting to change values in a lower classified tuple, but it may also occur because of a deliberate action in form of a cover story, where lower cleared users should not be supported with the proper values of a certain fact. Some researchers state that using polyinstantiation for establishing cover stories is a bad idea and should not be permitted. However, if supported it may not occur within the same access class. [MLS integrity property 4]: Polyinstantiation Integrity. R satisfies polyinstantiation integrity if for every Rc and each attribute Ai the functional dependency A Ci  ® Ai (i=1.. n) holds. Property 4 states that the apparent key A and the classification of an attribute correspond to one and only one value of the attribute, i. e. polyinstantiation may not occur within one access class. In many DBMSs supporting a MLS relational data model multilevel relations exist only at the logical level. In such systems multilevel relations are with t’[A, CA] = t[A, CA] and for Ai I A t’[Ai, Ci] ={ t[Ai, Ci], if t[Ci] ? c’ null, t[CA], otherwise. 18 decomposed into a collection of single-level base relations which are then physically stored in the database. Completely transparent multilevel relations are constructed from these base-relations on user demand. The reasons behind this approach are mostly practical. Firstly, fragmentation of data based on its sensitivity is a natural and intuitive solution to security and secondly, available and well-accepted technology may be used for the implementation of MLS systems. In particular, the decomposition approach has the advantage that the underlying trusted computing base (TCB) needs not to be extended to include mandatory controls on multilevel relations and this helps to keep the code of the TCB small. Moreover, it allows the DBMS to run mostly as an untrusted application on top of the TCB. We will come back to this issue in Section 3 when discussing different implementations of Trusted DBMSs. 2. 2. 3 MAC-based Structural Limitations Although being more restrictive than DAC models MAC techniques need some extensions to be applied to databases efficiently. In particular, we see as limitations the following drawbacks in multilevel secure databases and mandatory access controls based on BLP:  · Granularity of security object It is not yet agreed about what should be the granularity of labeled data. Proposals range from protecting whole databases, to protecting files, protecting relations, attributes, or even certain attribute values. In any case, careful labeling is necessary because otherwise it could lead to inconsistent or incomplete label assignments.  · Lack of automated security labeling technique Databases usually contain a large collection of data, serve many users, and labeled data is not available in many civil applications. This is the reason manual security labeling is necessary which may result in an almost endless process for large databases. Therefore, supporting techniques are needed, namely guidelines and design aids for multilevel databases, tools that help in determining the relevant security objects, and tools that suggest clearances and classifications.  · N-persons access rules Because of information flow policies higher cleared users are restricted from writing-down on lower classified data items. However, organizational policies may require that certain tasks need to be carried out by two or more 19 persons (four-eyes-principle) having different clearances. As an example onsider subjects s1, s2 with clear(s1) clear(s2), data item d with class(d) = clear(s2) and the business rule that writing of s2 on d needs the approval of s1. Following Bell-LaPadula’s write-access rule would require the same level of clearance for s1 and s2. This may be inadequate for business applications of MLS database technology. 2. 3 The Adapted Mandatory Access Control Model Adapting mandatory access controls to better fit in to general purpose data processing practice and offering a design framework for databases containing sensitive information are the main goals of the Adapted Mandatory Access Control (AMAC) model. In order to overcome the MAC-based limitations stated above AMAC offers several features that assist a database designer in performing the different activities involved in the design of a database containing sensitive information. For AMAC as a security technique for databases we see the following advantages:  · The technique supports all phases of the design of a database and can be used for the construction of discretionary protected as well as for the construction of mandatory protected databases.  · In the case mandatory protection is required a supporting policy to derive database fragments as the target of protection is provided. This overcomes the discussion about what should be the granularity of the security object in multilevel systems.  · In the case mandatory protection is required automated security labeling for security objects and subjects is supported. Automated labeling leads to candidate security labels that can be refined by a human security administrator if necessary. This overcomes the limitation that labeled data often is not available.  · In AMAC security is enforced by using database triggers and thus can be fine-tuned to meet application dependent security requirements. For example, the n-eyes-principle may be supported in some applications and may not in others where information flow control is a major concern of the security policy. We will first give a general overview of the AMAC technique which is followed by a more formal discussion and an example. 20 2. 3. 1 AMAC General Overview Adapted mandatory security belongs to the class of role-based security models which assume that each potential user of the system performs a certain role in the organization. Based on their role users are authorized to execute specific database operations on a predefined set of data. The AMAC model does not only cover access control issues but includes in addition a database design environment with main emphasis on the security of resulting databases. Resulting databases may be implemented in DBMSs supporting DAC only or supporting DAC and MAC. The technique combines well known and widely accepted concepts from the field of data modeling with concepts from the area of data security research. By using AMAC the following design phases for security critical databases can be identified. (1) Requirements Analysis and Conceptual Design. Based on the role they perform in the organization the potential users of the database can be classified into different groups. For different roles data and security requirements may differ significantly. The Entity-Relationship (ER) model and its variants serve as an almost de facto standard for conceptual database design and have been extended in AMAC to model and describe security requirements. The security and data requirements of each role performed in the organization are described by individual ER-schemas and form the view (perception) of each user group on the enterprise data. Please note, in this setting the notion of a view denotes all the information a user performing a certain role in the organization is aware of. This information includes data, security requirements, and functions. Thus, the notion of views appears different from that in a DAC environment. In order to arrive at a conceptualization of the whole information system as seen from the viewpoint of the enterprise AMAC uses view integration techniques in a further design step. The resulting conceptual database model is described by a single ER-schema extended by security flags indicating ecurity requirements for certain user roles. (2) Logical Design. In order to implement the conceptual schema into a DBMS a transformation from the ER-schema into the data model supported by the DBMS in use is necessary. AMAC contains general rules and guidelines for the translation of ER-schemas into the relational data model. Output of the transformation process is a set of relational schemas, global depende ncies defined between schemas and necessary for database consistency during further design steps, and a set of views, now describing access requirements on relation schemas. If the DBMS that should hold the resulting database is only capable to support DAC the relational schemas are candidates for implementation and the view descriptors are used for discretionary access controls. In the case the DBMS under consideration supports MAC further design activities are 21 necessary. The Requirements Analysis, Conceptual and Logical Design phases in AMAC are described by Pernul and Tjoa (1991). (3) The AMAC security object. In order to enforce mandatory security it is necessary to determine security objects and security subjects which are both subject to security label assignments. In AMAC a security object is a database fragment and a subject is a view. Fragments are derived by using structured database decomposition and views are derived by combining these fragments. A fragment is the largest area of the database to which two or more views have access in common. Additionally, no view exists that has access to a subset of the fragment only. Pernul and Luef (1991) have developed the structured decomposition approach and the automated labeling policy. Their work includes techniques for a lossless decomposition into fragments and algorithms to keep fragmented databases consistent during database update. It should be noted that a database decomposition into disjoint fragments is a natural way to implement security controls in databases. (4) Support of automated security labeling. As in most IT applications labeled data is not available, AMAC offers a supporting policy for the automated security labeling of security objects and security subjects. Automated labeling is based on the following assumption: The larger the number of users cleared to access a particular fragment, the lower is the sensitivity of the contained data and thus, the lower is the level of classification that needs to be provided for the fragment. This assumption seems to be valid because a fragment that is accessed by many users will not contain sensitive information and at the other side, a fragment that is accessible for few users only can be classified as being highly sensitive. Views (respectively the users having the view as their access window to the data) are ordered based on the number of fragments they may access (they are defined over) and additionally based on the assigned classifications for the fragments. In general, a view needs a clearance that allows the corresponding users to access all fragments the view is defined over. The suggested classification class(F) applies to the whole fragmental schema F as well as to all attribute names and type definitions for the schema while the suggested clearance clear(V) to all transactions executing on behalf of a user V. It should be noted that classifications and clearances are only candidates for security labels and may be refined by a human database designer if necessary. (5) Security Enforcement. In AMAC the fragments are physically stored and access to a fragment may be controlled by a reference monitor. Security is enforced by using trigger mechanisms. Triggers are hidden rules that can be fired (activated) if a fragment is effected by certain database operations. In databases security critical operations are the select (read access), the insert, 22 elete, and update (write accesses) commands. In AMAC select In AMAC security constraints are handled during database design as well as during query processing. During database design they are expressed by the database decomposition while during query processing they are enforced by the trigger mechanisms. In the following we will give the technical details of the decomposition process, the decomposition itself, the automated security labeling proc ess, and certain integrity constraints that need to be considered in order to arrive at a satisfactorily fragmentation. In AMAC it is assumed that Requirements Analysis is performed on an individual user group basis and that the view on the database of each user group is represented by an Entity-Relationship (ER) model. The ER model has been extended to cover in addition to data semantics the access restrictions of the user group. The next design activity is view integration. View integration techniques are well established in conceptual database design and consist of integrating the views of the individual user groups into a single conceptual representation of the database. In AMAC the actual integration is based on a traditional approach and consists of two steps: integration of entity types and integration of relationship types (Pernul and Tjoa, 1991). During the integration correspondences between the modeling constructs in different views are established and based on the different possibilities of correspondences the integration is performed. After the integration the universe of discourse is represented by a single ER diagram extended by the access restrictions for each user group. The next step is the transformation of the conceptual model into a target data model. AMAC offers general rules for the translation into the relational data model. The translation is quite simple and results into three different types of modeling constructs: relation schemas (entity type relations or relationship type relations), interrelational dependencies defined between relation schemas, and a set of view descriptors defined on relation schemas and representing security requirements in the form of access restrictions for the different user groups. 23 In the relational data model user views have no conceptual representation. The decomposition and labeling procedure in AMAC is build around the concept of a user view and this makes a simple extension of the relational data model necessary. Let RS(ATTR,LD) be a relation schema with ATTR a set of attributes {A1, ,An}. Each AiIATTR has a domain dom(Ai). LD is a set of functional dependencies (FDs) restricting the set of theoretically possible instances of a relation R with schema RS (i. e. ?i dom(Ai)) to the set of semantically meaningful. A relation R with schema RS is a set of distinct instances (tuples) {t1, ,tm} of the form a1, ,an where ai is a value within dom(Ai). Let RS1(ATTR1,LD1) and RS2(ATTR2,LD2) be two relation schemas with corresponding relations R1 and R2. Let X and Y denote two attribute sets with XIATTR1 and YIATTR2. The interrelational inclusion dependency (ID) RS1[X]IRS2[Y] holds if for each tuple tIR1 exists at least one tuple t’IR2 and t[X]=t’[Y]. If Y is key in RS2 the ID is called key-based and Y is a foreign key in RS1. Let V={V1, ,Vp} be a set of views. A view Vi (ViIV, i=1.. p) consists of a set of descriptors specified in terms of attributes and a set of conditions on these attributes. The set of attributes spanned by the view can belong to one or more relation schemas. View conditions represent the access restrictions of a particular user group on the underlying base relations. For each user group there must be at least one view. The concepts defined above serve as the basis of an AMAC conceptual start schema SS. SS may be defined by a triple SS(A,GD,V), where: A = {RS1(ATTR1,LD1), ,RSn(ATTRn,LDn)} is a set of relation schemas, GD = {ID1, ,IDk} is a set of key-based IDs, and V = {V1, ,Vm} is the set of views. In the case discretionary protection is sufficient, the relational schemas are candidates for implementation in a DBMS, the views may be used to implement content-based access controls and the set GD of global dependencies may be associated with an insert-rule, a delete-rule, and a modification-rule in order to ensure referential integrity during database peration. In the case DAC is not sufficient and MAC should be supported it is necessary to determine the security objects and subjects and to assign appropriate classifications and clearances. In order to express the security requirements defined by means of the views a decomposition of SS into single level fragments is necessary. The decomposition is based on the derived view structure and results in a set of fragmental schemas in a wa y, that no view is defined over a subset of a resulting schema only. A single classification is 24 ssigned to each fragmental schema and the decomposition is performed by using a vertical, horizontal, or derived horizontal fragmentation policy. A vertical fragmentation (vf) results into a set of vertical fragments (F1, ,Fr) and is the projection of a relation schema RS onto a subset of its attributes. In order to make the decomposition lossless the key of RS must be included in each vertical fragment. A vertical fragmentation (vf) R=(F1, ,Fr) of a relation R is correct, if for every tuple tIR, t is the concatenation of (v1, vr) with vi tuple in Fi (i=1.. r). The (vf) is used to express ‘simple’ security constraints that restrict users from accessing certain attributes. The effects of (vf) on an existing set of FDs have been studied by Pernul and Luef (1991) and the authors show that if R is not in 3NF (third normal form) some FDs might get lost during a decomposition. In order to produce a dependency preserving decomposition in AMAC they have suggested to include virtual attributes (not visible for any user) and update clusters in vertical fragments in the case a schema is not in 3NF. A horizontal fragmentation (hf) is a subdivision of a relation R with schema RS(ATTR,LD) into a subset of its tuples based on the evaluation of a predicate defined on RS. The predicate is expressed as a boolean combination of terms, each term being a simple comparison that can be established as true or false. An attribute on which a (hf) is defined is called selection attribute. A (hf) is correct, if every tuple of R is mapped into exactly one resulting fragment. Appending one horizontal fragment to another leads to a further horizontal fragment or to R again. A (hf) is used to express access restrictions based on the content of certain tuples. A derived horizontal fragmentation (dhf) of a relation Ri with schema RSi(ATTRi,LDi) is partitioning RSi by applying a partitioning criterion that is defined on RSj (i? j). A (dhf) is correct if there exists a key-based ID of the form Ri[X]IRj[Y] and each tuple tIRi is mapped into exactly one of the resulting horizontal fragments. A (dhf) may be used to express access restrictions that span several relations. A view Vi (Vi IV) defined on A represents the area of the database to which a corresponding user group has access. Let F (F=ViCVj) be a database fragment then F represents the area of the database to which two groups of users have access in common. If F=Vi Vj, then F is only accessible by users having view Vi as their interface to the database. In this case, F represents data which is not contained in Vj and must therefore not be accessible for the corresponding user set. From the point of view of a mandatory security policy a certain level of assurance must be given that users Vj are restricted from accessing F. In AMAC this is given by separation. For example, fragment (Vi 25 Vj) is separated from fragment (VjVi) and fragment (Vi CVj) even if all fragments belong to the same relation. The construction of the fragments makes a structured database decomposition necessary and in order to support mandatory access controls, the access windows for the users is constructed in a multilevel fashion such that only the necessary fragments are combined to form a particular view. Let Attr(V) be the attrib ute set spanned by view V and let the subdomain SD(V[A]) be the domain of attribute A valid in view V (SD(V[A])IDom(A)). Two particular views Vi and Vj are said to be overlapping, if: $Ao(AIAttr(ViCVj) and SD(Vi[A])CSD(Vj[A]) ? ?, otherwise, Vi and Vj are called isolated. The process of decomposing A (A={RS1(ATTR1,LD1), ,RSn(ATTRn,LDn)}) is performed for any two overlapping views and for each isolated view by using the (vf), (hf), and (dhf) decomposition operations. It results in a fragmentation schema FS={FS1(attr1,ld1), ,FSm(attrm,ldm)} and a corresponding set of fragments F (F={F1, ,Fm}). If Ei ATTRi = Ej attrj (i=1.. n, j=1.. m) the decomposition is called lossless and if Ei LDi I Ej ldj (i=1.. , j=1.. m) it is called dependency preserving. Please note that (hf) or (dhf) may result in additional FDs. A fragmental schema FSjIFS is not valid if for any view V ($Fj’IFj) (V? Fj’, VUFj). Here, V? F denotes that users with view V have access to fragment F while VUF means that F is not included in view V. To illustrate the concepts defined above we will apply the fragmentation policy to the example given in the Introduction of this Chapter. We assume, that the Requirements Analysis has been performed and that the resulted ER model has been translated into the following start schema: SS = ( A= { Employee ({SSN, Name, Dep, Salary}, {SSN  ® Name, Dep, Salary}), Project ({Title, Subject, Client}, {Title  ® Subject, Client}), Assignment ({Title, SSN, Date, Function}, {Title, SSN  ® Date, Function})}, GD ={AssignmentDatabase SecurityIProjectDatabase Security, Assignment[SSN]IEmployee[SSN]}, V = {V1, V2, V3, V4, V5}) The security policy of the organization requires to represent the following conditions on the security:  · View V1 represents the access window for the management of the organization under consideration. Users with view V1 should have access to 26 the whole database. Views V2 and V3 represent users of the pay-office department. Their requirements include access to Employee and Assignment. For V2 access to Employee is not restricted. However, access to attribute Function should only be provided in the case the employees’ Salary ? 100. Users V3 should only have access to employees and their assignments in the case the attribute Salary ? 80.  · View V4 has access to Project. However, access to attribute Client should not be supported in the case the subject of a project is ‘research’.  · View V5 represents the view of the users of the quality-control department. For them to perform their work it is necessary to have access to all information related to projects that have a subject ‘development’, i. e. to the project data, to the assignment data, and to the data concerning assigned employees. For security req

Friday, November 22, 2019

Reaction Paper Essay Example | Topics and Well Written Essays - 500 words - 9

Reaction Paper - Essay Example An astounding thing about the film and the exposition itself was the scale that was present. Normally, a fair or event like that would have small exhibits which would be dwarfed by the crowds. For the Chicago exposition, this was far from the case. Instead the exposition hosted complex structures, many of which were at large scales. I imagine that it must have been dazzling, like visiting another world. Everything that was being showcased was beautiful, exciting and compelling. It seemed like it would have been an amazing place to visit and that there would have been so many things that were interesting to see and to do. The impact that the exposition had on the city itself was amazing. Through the use of white building materials, the exposition really was a white city, standing out from the environment around it. This must have been amazing to see, and transported visitors away from their day-to-day life and routines to a world that was entirely different. The size of the exposition and the amount that there was to see must have kept people busy for days. Another aspect of the film that was fascinating was the way that the technology was showcased. One aspect of this was the focus on electricity, which provided an indication to visitors that electricity was a safe and reliable form of energy. A key presenter for this section of the exposition was Nikola Tesla, who is renowned today for his role in the invention of the alternating current. This aspect of the exposition was amazing, because the exhibits that were being shown to the people at the fair were new and astounding, yet many of them would become technological standards for later life. Many people today cannot imagine living without electricity, yet for the people going to the exposition it was brand new. I felt that this contrast was amazing, and longed to go back to the time where progress had this kind of wonder associated with it. Although there were

Wednesday, November 20, 2019

Employment Law - Independent Contract Case Study Essay

Employment Law - Independent Contract Case Study - Essay Example The IRS defines an employee using existing common-law rules (IRS P-15a 4). The IRS maintains that it makes no difference how you label the relationship because the relationship between the employer and the person performing the service defines the relationship (IRS P-15a 4). The relationship that existed between Ark Bark and Joshua was bound by an oral agreement which was not put to writing. The employer, according to the case study, maintained an employer/employee relationship with Joshua by staying in frequent contact with him via telephone. It demonstrates that the employer, not Joshua, was in charge of maintaining the relationship that existed between them. The IRS tells us to examine the element of behavioral control between the parties (IRS P-15a 6). Behavioral control, whether it rests with the employer or the person performing the service, is significant in identifying the nature of the relationship. Behavioral control establishes â€Å"[†¦] whether a business has the right to direct and control how the worker does the task for which the worker is hired [†¦] (IRS P15a 6).† An employee, the IRS states, must generally follow the employer’s instructions on when, how, and where to perform the work (IRS P-15a 6). The employer gives the employee these instructions, that normally include the tools to use in performing the work, identifies who will assist the employee in accomplishing the work, where the employee must purchase or receive the relevant supplies and equipment necessary to perform the work, who performs each component of the task and in what order of priority it is performed (IRS P-15a 6). In the case study presented, we cannot say the employer issued directions to Joshua on when, how, and where to perform the work because we do not know the substance of the sixty-eight telephone calls made to Joshua by Ark Bark’s vice president. The employer did not provide Joshua the tools to perform the sales work, although

Monday, November 18, 2019

Novel Essay Example | Topics and Well Written Essays - 1500 words

Novel - Essay Example The story of their destruction started from their elopement, which was decided because Manon was not accepted by Des Grieux’s father. On the other hand, â€Å"The Sorrows of young Werther† indicate class as a burden for Werther, who is unable to endure the difficulties of class. Werther develops a love for simplicity for peasants and likes their class. He is unable to endure the snobbishness of his own and upper classes. As far as â€Å"Silas Marner† is concerned, class is depicted by means of physical locations. The home of Silas Marner is the lowliest place while the home of Godfrey Cass is the highest place of the locality but in spite of all the riches, the wife of Godfrey is jealous of Silas and Eppie because she is unable to bear a child. All the three novels take class with a different perspective but all their perspectives are persuasive and influential in different places. The theme of class id dealt differently in each writing. Class is a reality that i s considered differently by all the three writers. The novel, Manon Lescaut, takes the theme of love and combines it to the theme of class. The example of class based society can be taken from the incident when Des Grieux has to make a decision to elope in order to marry his beloved, who belongs to a lower class family. Manon Lescaut is a story of a lover who leaves his noble and landed family because of his beloved. The protagonist of the novel le Chevalier Des Grieux belongs to a noble and rich family and his father keeps higher hopes with his son but with the passage of time, Des Grieux’s father is disappointed as Des Grieux elopes with her beloved, Manon Lescaut. At various occasions in the novel, there are indications of Manon Lescaut’s intention of leaving Des Grieux because of his lack of money (Arnold 1981). He belonged to a noble class but with the passage of time, he is unable to maintain his social status because he has left his hereditary wealth for his beloved, who was

Saturday, November 16, 2019

Bio Mechanical Analysis Of The Golf Swing Physical Education Essay

Bio Mechanical Analysis Of The Golf Swing Physical Education Essay Since hitting of the ball may be repeated an average of 50 times during an 18-hole course, or 300 times or more during a practice session by a professional, it is easy to understand that, for both professional and recreational players, injuries can occur either through overuse or bad technique through actions causing severe trauma (Kohn 1996). McCaroll (1990) found that professionals injured their self less frequently than that of amateurs, and that the causes of injury were due to poor swing mechanics. Injuries to these musculoskeletal structures are caused either by overload of tension, twisting of the tissues or the strain of the physical impact of hitting the ball (Stover 1976). The aim of this essay is to review and analyse the golf swing biomechanically to identify the correct technique to help prevent common golfing injuries. The golf swing will be broken down in to 6 phases; ball address, end of backswing, forward swing/acceleration, ball impact, early follow through, and late follow through. For each of these 6 phases the human body undergoes biomechanical stresses likely to provoke injuries, these injuries and their prevention will be discussed during each phase. Phase 1 and 2 Ball Address and End of Back Swing There are several factors to consider during the ball address to ensure an effective technique for force production and injury prevention. Bad posture can cause skeletal and joint misalignment, which will affect the pattern of stress imposed on tissue and the area of force distribution (McGinnis 1999). Therefore if the players posture is less then optimal they begin and end movement in an aberrant position and as a result the chances of accelerating joint wear are increased. The attainment of the optimal pre-stroke posture is achieved through a good starting position i.e. even weight distribution on both feet with a shoulder width stance. This will ensure a significant base of support that will promote stability and equilibrium to the golfer as the centre of gravity moves throughout the shot. Therefore allowing maximal potential kinetic energy to be generated through the club. If the stance is too wide truck rotation will be reduced placing greater strain on the spine, causing injury. Alternatively, if the feet are too narrow, reducing the base of support, it could lead the golfer to lose control of the swing due to a decrease in stability. To help prevent injuries to lower back during the entire swing it is essential to have good core stability. (Wilson 2005 p. 316) describes the core as  the ability of the lumbo-pelvic hip complex to prevent buckling of the vertebral column and return it to equilibrium following perturbation. As a result, core stabi lity is essential to help stabilise the body which in effect will help to support the antagonist of the abdominal, therefore preventing injury to the lower back. As joint mechanics are less than ideal with poor posture, joints will not effectively move around a central axis, therefore preventing angular motion. With poor posture, the stabilising muscles of the body (those that help maintain joint axis rotation), become long and weak. In opposition, the movement muscles of the body become overused, short and tight. A continuation of this cycle leads to further imbalance, increasing the chances of injury (Chek 1998). Once good posture is achieved there should be slight anterior flexion of the trunk at the hips and the shoulders, knees and feet must be aligned. The back must be kept straight while keeping the vertebral column perpendicular to the ground in the frontal plane (although the upper body of the player remains leaning forward towards the ball to allow a lower centre of gravit y to optimise equilibrium throughout the swing). If your centre of gravity is not distributed evenly when you take your setup due to a postural fault or incorrect stance the  centre of gravity may be too far back, which in effect will cause the legs to move before the backswing is complete. Consequently power is supplied by the arms and shoulders only, which again creates excessive force through the shoulder and elbow. In the second phase, the backswing, a simultaneous rotation to the right side around the spinal vertical axis of the knees, hips and upper limbs is executed. This raises the club to its highest point in order to obtain the widest possible arc of motion (Adlington 1996) Injuries related with the address and backswing of the golf swing are: Frontal flexion at the dorsolumbar spine rather than at the hips increases the possibility of vertebral hypermobility and unbalanced muscular stress during the backswing (Hosea 1996) Overextended, straight arms (especially the left) or hyperextend elbows and abnormally high muscular tension in the forearms (too tight a grip) reduces the effectiveness in creating speed in the downswing and can induce elbow and wrist injuries at ball impact (Gosheger 2003) A grip without interlocking hands or too loose a grip increases the danger of dropping the club causing a loss of accuracy on ball impact and injury of the elbow, wrist or hand through ground impact. An excessively long backswing may cause trunk over-rotation injury or throw the golfer off balance leading to ground collision injuries. Excess backswing also increases tension in the left thumb and right wrist. Excess arm/shoulder elevation on the backswing, with the left arm abducting the left shoulder, impinges on the subacromial tissues (tendons, bursa) and requires good stabilisation from the rotator cuff muscles. If the bursa continues to be impinged this could lead to the bursa becoming inflamed causing bursitis.( Jobe 1996) Leftward spinal lean, instead of being parallel to the ground, during the rightward weight shift increases the possibility of a conflicting spinal curve posture at the end of the follow through. The rightward weight shift abnormally collected on the outside of the right foot can cause a loss of equilibrium and right ankle sprain.( McCarroll 1990) Phase 3 and 4 Forward Swing/Acceleration and Ball Impact The third phase of the golf swing is characterised by the activation of an anatomical multi lever system which gives the club a downswing in a rotational, angular trajectory and a maximum speed. A lever system is rigid or semi-rigid object that is capable of rotating around a fulcrum (McLeste 2008). In a golf swing a third class lever is present and consists of the golf club and the golfers arm. Levers increase speed and power, therefore maintaining a longer lever will increase power production. If the lever is shortened due to flexing the elbow on impact it will take a greater force to obtain the same power. Therefore excessive force will be transferred into the elbow. If the fulcrum is so far off-set away from centre, a lot of muscular effort must go into the grip of the club at one end in order to move the club head at the other. These levers are activated in sequence from the ground level upwards; from the feet to the wrists. Prior to the completion of the backswing, good golfers are gathering kinetic energy from the ground upwards in preparation for the downswing. As the feet push into the ground forces are generated and then transferred back into the body, in turn accelerating firstly through the hips, shoulders, arms and then club head. This is an effective use of the kinetic chain by generating forces from the bottom up which will allow for an efficient smooth motion. If the kinetic chain breaks down due to inconsistency in the swing technique this could lead to injuries as the force is not being controlled and distributed evenly through the body. The risks for injuries in the downswing and ball impact occur in the zones of greatest muscular activity. There is also risk for injury to the elbows, wrists and hands if any of these 3 structures is held too stiff. (Kohn 1996) Injuries related with the down swing and ball impact of the golf swing are: Thoracic and abdominal muscular strains may arise after forceful upper body rotation on the downswing. (Stover 1976) The leftward weight shift can create considerable compressive forces on the left leg (hip, knee, ankle and foot) which are hazardous to individuals with osteoarthritis. (Hahn 1991) Lateral or medial epicondylitis (golfers elbow) can be sustained at impact if the grip is too tight or the elbows are held too tightly or are hyper extended. Grips size is therefore important as too small a grip will make the golfer grip tightly. Clubs of proper weight, length, and grip are therefore important in significantly reducing the vigorous forces generated within the  elbow (Kocker 2000) Excessive wrist flexion/extension in the downswing, or hitting the ground after losing equilibrium, can cause serious hand and wrist injuries. (Murray Cooney 1996). Phase 5 and 6 Follow Through and Late Follow Through The follow through is essentially the deceleration of the body after contact with the ball has been made. Deceleration by the body occurs as a result of the absorption of energy back up through the kinetic chain of the body. The danger for injuries to the lumbar dorsal zone arises if the deceleration stops too abruptly or if the final range of motion of spinal rotation is too prominent (Parnianpour 1988). Posterior shoulder injuries are most likely during the follow through due to the high inertia and large acceleration (Atwater 1979). At the very top of the follow through, the spine is rotated to the left, and the hips are fully facing the target which enlists the help of the abdominal muscles to support the spine, while the wrist joints abduct working the wrist extensors to drop the club behind the back. At impact, the body shifts back to the relatively symmetrical position for a very short time, then the centre of gravity shifts towards the target as the mass of the arms and club move in that direction. To golfer must dissertate and control this energy if he intends to remain on his feet. Research by Fleisig (1995) indicated that at impact the left foot (right-handed golfer) is supporting 80% to 95% of the golfers weight, therefore concluding it is essential for golfers to wear spikes to help control this energy. Gatt (1998) supports this theory stating they provide additional traction, allowing the forces generated by the lower body to be transferred into the club. Injuries associated with the early and late follow through are: Shoulder ligaments and rotator cuff muscles can experience excessive mechanical stress (tension or compression) in a forceful follow through (Hovis 2002) Injury to the hips or dorsolumbar spine may arise due to the deceleration of the follow through is too rapid (Parnianpour 1988) An excessively forceful drive, inducing a reversed C lordotic spinal curvature, may induce unusual high stresses on the dorso-lumbar vertebral bodies, in particular on the posterior joints (Batt 1993) An off-balance weight transfer or slide can cause an ankle or foot sprain as well as knee injury Injury Prevention Flexible muscles and tendons are extremely important in the prevention of most strain or sprain injuries. It is important to have a significant amount of muscular strength and muscle endurance as this will affect the magnitude of the loading and shock absorption on the body. Joint flexibility will affect the load pattern of segments (McGinnis1999).When muscles and tendons are flexible and supple, they are able to move and perform without being over stretched. If, however, muscles and tendons are tight and stiff, it is quite easy for those muscles and tendons to be pushed beyond their natural range of movement and therefore this will increase the risk of injury. When this happens, strains, sprains, and pulled muscles occur. In addition for the need for flexibility the following strategies aid to prevent golfing injuries: Dorsolumbar spine Injuries sprain, muscular strain, herniated disc and arthrosis (Hosea1996). Preventive techniques Straight back posture, maintaining joint alignment and weight transfer during the golf swing Speed control during trunk rotation (i.e. use of the kinetic chain) Reduction of the shoulder range of motion and trunk Effective use of angular motion Dorsolumbar conditioning through flexibility and muscular strengthening exercises Elbow, wrist and hand Injuries Epicondylitis (Golfers Elbow), chronic sprain, tendinitis, carpal tunnel syndrome and fracture (Murry Cooney 1996) Preventive techniques Reduction of wrist flexor/extensor (grip) tension and loosening of elbows Reduction of excessive wrist motion Maintaining good balance during weight transfer Wrist and finger flexor/extensor conditioning for flexibility and strength Use of a counter-shock brace, a more flexible, lighter golf club (graphite) or club counter-shock device (Metz 1999) Shoulder Injuries Tendinitis, bursitis, glenohumeral instability, sprain (Jobe 1996) Preventive techniques Reduction of the angular shoulder displacement at backswing Control of excessive arm motion at follow through Conditioning exercises for flexibility (posterior capsule) and rotator cuff strengthening to help stabilise the shoulder joint (Hovis 2002) Conclusion In conclusion restrictions in the body in terms of flexibility, muscular strength, endurance, or power can create boundaries in the swing from a biomechanical viewpoint. In addition, biomechanical defects in the swing itself limit the potential and kinetic energy outputs of the body. Injuries to the upper limb account for the majority of golf-related injuries. Most injuries occur as the club impacts the ball and are muscle-related due to the high forces and strain applied during the downswing. An understanding of how the body moves biomechanically to harness these forces and the muscle activity achieved during the golf swing will help athletes and coaches to understand why these injuries occur and the ways to prevent them in the future.

Wednesday, November 13, 2019

The U.S. and The S.O.A. :: Essays Papers

The U.S. and The S.O.A. In its dealings with foreign nations, the government of the United States has repeatedly rushed past seeking diplomatic solutions to problems and utilized its military superiority or money to achieve the outcome it desires, regardless of civilian casualties that might occur along the way. Time and again, it has violated human rights or contributed to such violations. In some cases, the actions of the government have backfired and an ally that the U.S. was assisting at one point in time to achieve its own ends reverses itself and becomes an enemy. Whether that happens or not, many well-informed citizens are concerned for the welfare of the peoples in other nations and what the United States government is doing to them. In a democracy, where majority rules, issues such as U.S. involvement in human rights violations needs to be brought to the attention of more citizens. For issues pertaining to Latin America, this is all too apparent. It is too often overlooked, yet the U.S. maint ains a strong influence on most, if not all, of its nations. All over the world, the United States government uses its influence to achieve its own goals, even when those goals harm the peoples of foreign nations. The solutions which the U.S. uses to solve its foreign problems are generally temporary and have many negative consequences in the long run. The two most noteworthy occurrences which show these results are the two most difficult issues facing America in the present day. The opponents that the United States now faces were originally assisted by the U.S. during the 1980s. The two foes are Osama bin Laden and Saddam Hussein. Osama bin Laden gained assistance from the CIA in 1979 in what has been called â€Å"the largest covert operation in the history of the CIA.†[1] This was during the Cold War period when the Soviets had invaded Afghanistan, causing an uproar by the Afghani people, who began a jihad against the Soviets. In order to stop the spread of Communism, the United States wanted to rid Afghanistan of the Soviets.[2] So, the CIA, using the Pakistan's military Inter-Services Intelligence (ISI) as a middle-man,2 assisted the Afghani fighters by dramatically increasing arms supplies -- a steady rise to 65,000 tons annually by 1987, by training them in guerrilla techniques, and by maintaining a "ceaseless stream" of CIA and Pentagon specialists who traveled to the secret headquarters of Pakistan's ISI.

Monday, November 11, 2019

I will Design and Carry Out my PEP on the Basis of me Being a Football Player Essay

I will design and carry out my PEP on the basis of me being a football player. I am 14 years and 6 months old and have been playing football since about the age of 5. I enjoy the game and I am quite good at it. Although I am quite good I would like to train to become better at the sport and increase my overall fitness level. I am generally fit but there is definitely room for improvement and I will look to do so. When I leave school I plan to join the British Army so I would like to become fit so that I can fulfil my plans. Over the 6 weeks that I carry out the training regime I will give it 100% and really try to improve my fitness and footballing skills. I want to make the best of my ability at football so I can enjoy what I do and hopefully it will benefit the Sunday league club that I play for. I play for Aspull Juniors. I have done so for 5 years now and enjoy playing for the team. I play in the centre of midfield and play in more of a defensive role. This position allows me to put a lot of effort in and influence the game. I am a good tackler of the ball and can pass good as well. For the job that I do on the football pitch I need to have a good stamina (so I can cope with the demands of the football math), good flexibility (so I don’t stretch my muscles when making tackles), good balance (to pass the ball and make vital tackles), strength (to out muscle opponents and kick the ball far), speed (to get to the ball quicker than the opponent), and good reaction time (this is so I can react to the ball quicker than an opponent.) My PEP should help me to improve all of these skills and as a result I will become a better football player. I have never suffered any long-term injuries of any kind and have no recurring injuries. Other sports that I enjoy to do are fishing, golf, tennis and table tennis. Although I do none of these sports competitively I am interested in them and have done for fun. PEP For my PEP I will use a pyramid session to gradually increase my fitness during the 6 weeks. I will use a badminton court as my guide and say that double the length of the court is equal to one length. I will increase the lengths as the program progresses to create an overload required to increase my fitness. I chose a pyramid session because I feel it is the most reliable way of increasing my fitness. Also I know that it will be easier to create an overload in either the amount of lengths or exercises that I do if I use a pyramid session. From when I have used this session in the past I have found that it always gives me a good workout and can be used to good effect. I will start and progress my PEP over the weeks using the FITT principal. I will increase the frequency by doing more exercises and by doing more running more often. I will increase the intensity by increasing the amount of exercise that will be done. I will do this by adding more lengths onto my pyramid session and more exercise in between. I will increase the time by putting more time into the exercises in between runs. The type will also be changed. I will change the fitness test that I will do after the pyramid sessions each week. The PEP that I have designed is one that I think will improve my overall fitness the most and also improve the skills that I need as a football player. It will start with a 5 minute jog. This jog will warm up my muscles so that they are not too stiff to stretch otherwise I will increase the chances of a ripped or torn muscle. After the jog I will move on to my stretches. They will be thoroughly carried out so not to allow any muscle injury whatsoever can occur. The stretches are one of the most important parts of the PEP and must be done with care and thought. If these are not done correctly than I will run the chance of pulling or tearing a muscle. The Pyramid Session starts by running the maximum amount of lengths you are wishing to do and then gradually working your way down until there are no more lengths to complete. In between lengths you are required to do exercises. For example, if I was planning to do 16 lengths I would do 16 lengths then a chosen exercise. After the exercise you then do 15 lengths then the exercise, then 14 lengths then a exercise and so on until there are no more lengths to complete. This Pyramid Session will progress throughout the 6 weeks of the PEP. Week 1 I will be doing 10 lengths, Week 2 and 3 I will be doing 12 lengths, Week 4 and 5 I will do 14 lengths and for the final week I will do 16 lengths. As the weeks progress an overload is created which will help me improve my fitness. The Warm Up For my warm up I will be doing a 5 minute jog around the All Weather pitch. The warm up is to warm the muscles up before stretching so I do not pull a muscle. I will time myself and be sure not to strain myself as this too could result in a pulled muscle if not careful. The Leg Exercises – Squats, Burpees, Switch Overs, Star Jumps These exercises will build up my leg muscles and allow me to put more power into a shot or long pass. These exercises will build up the strength and power in my legs and will allow me to hit a ball further and this will improve my skill as a football player. I have done more leg exercises than arm and body exercises because I feel that my legs are needed more on a football pitch. The Body Exercises – Sit Ups, Crunches The body exercises that I will do will allow me to build up my middle body muscles and will help me to become stronger and flexible in that area. This will help me when I play football because I will be able to adjust the middle part of my body easier and this will help me when I am playing. The Arm Exercises – Bench Press, Press Ups By doing these arm exercises it will improve my upper body strength and this will make it easier to shrug off opponents when challenging for a ball in a game. The exercises will build up the muscles in my arms and this can help when taking a throw-in. The Cool Down For the cool down I will do a light jog and then stretch. The cool down is to prevent lactic acid from settling in the muscles and producing cramps. This is just as important as the warm up and is needed to prevent injury after the PEP. Stretches Hamstring- I would sit on the ground then bend over front wards and touch the top of my shin, I would hold this for 10 seconds. Then I would sit up rest and then bend over front wards again only this time touching the toes rather than the shin. Quads- I would stand and balance myself against a wall with one arm then I would grab the left leg bend it backwards so the foot is touching my bum and hold for 10 seconds. Then I would stop rest and change legs. Groin Stretch- I would sit on the ground and put the soles of each foot together in a yoga sort of position. Then slowly put pressure on the inside of each leg to stretch the groin. Upper Arm- Place one arm in front of me and place the other arm underneath the arm that is held out and grab the shoulder. After this swap arms and do exactly the same. Hold each stretch for 10 seconds. Week 1 The warm up and the stretches went well and I then began my Pyramid Session. I had planned to do 10 lengths this week. I found that the Pyramid Session worked well. I completed the 10 lengths with ease but the exercises were quite challenging. At the end of all the lengths and exercises I found myself out of breath but I was pleased with the work I had done. I then went out onto the all weather pitch to do a 50 metre sprint. I did the sprint in 8.12 seconds which was a personal best. After the sprint I did a 5 minute jog and then stretched for 5 minutes. Evaluation I was very pleased with what I did this week but thought that I could handle more lengths than what I had done. The exercises that I did were quite demanding but I thought they would be easier to handle next week and was looking forward to the challenge. I was extremely pleased with the speed that I achieved in the 50 metre sprint and although it wasn’t a huge amount of time I did beat my personal best. Week 2 This week I had set myself 12 lengths to do but I wasn’t particularly worried about the task ahead. I started off with the 5 minute jog and a thorough stretch and then I began my Pyramid Session. The session went well again this week. Similar to last week I found that the exercises were again quite tough and challenging but the lengths were completed without much difficulty. After the Pyramid Session this week, I had set my self the throw/catch ball test. This was not physically challenging but I had to concentrate to get the 35 score that I got. This was not the best score I had ever had but I was pleased with the result. Evaluation I was again pleased with this week. The increase in lengths never really affected my performance this week. They were more challenging than the previous week but never caused a major problem throughout the session. The throw/catch ball test that I did was more about finding a rhythm and concentrating rather than a physical test. Week 3 After the initial warm up and stretch I moved onto another week of the 12 length Pyramid Session. This week it again never caused a huge problem but I was still tired towards the end of the session. The exercises still caused similar problems as they did in the first week and were tiring. It was this week when I began to feel an improvement in my fitness. After I completed the Pyramid Session I then went and did the muscular endurance test in the hotel foyer. My previous best at this test was 100 seconds but this week I nearly doubled that score with 190 seconds. I was extremely pleased with this result. At the end of the session I did a 10 minute cool down. Evaluation I found that the 12 lengths didn’t pose too much of a problem for me this week and I was looking forward to the challenge of 14 lengths next week. I think that the exercises again provided a challenge for me and I began to feel the improvement in my fitness. I was extremely pleased with the score I achieved in the muscular endurance test. I think that I did well this week and was looking forward to the next few weeks ahead. Week 4 Due to a Dentist appointment I was unable to complete the regime at school. As a result I set up a training course on a football field behind my house and carried out my session to the best of my ability taking the environment and lack of equipment into condition. I worked hard for 1 hour and was pleased with the workout I had. Week 5 This week was my first attempt in school of attempting the 14 lengths I had set. Firstly, I did the warm up and stretches then got started with the Pyramid Session. It began like the others had but towards the end I found that this session was a lot more tiring than the previous weeks. At the end my legs were aching and I was really tired. I had created the overload and felt the affect. Although I was tired I was pleased with the task I had done and was looking to the week ahead. The test this week was a standing broad jump. I managed to get a score of 1 metre 52 centimetres. I was quite pleased with the score although it was not a personal best. After the test I went outside where I did a 5 minute jog and stretched off to avoid cramped muscles. Evaluation I was pleased with the effort that I put in today and could feel a definite improvement in my fitness. I thought that 14 lengths were very challenging and along with the leg, arm and middle body exercises produced a Pyramid Session which would challenge me. The standing broad jump that I did was not spectacular but I was pleased with the result. Week 6 For this week I was supposed to do 16 lengths, but because I missed week 4 I decided that I would carry on with 14 lengths. I went outside and did the warm up followed by the stretches then went inside to carry out the Pyramid Session. The 14 lengths were challenging but I felt an improvement in my fitness and they were easier to complete than the lengths last week. The test for my final week was a repeat of the throw/catch ball test. I carried it out in the Sports Hall and beat the score I had gotten previously. I got a score of 33, beating the score of week 2 and equalling my personal best. Evaluation I was pleased with the work that I had done in my final week. I found that the 14 lengths in the Pyramid Session were easier to complete than the previous week. I was pleased with the level of my fitness and was pleased with the score I achieved in the throw/catch ball test. Final Evaluation Throughout my PEP I have seen my overall fitness gradually increase from week to week. I would definitely say the regime has been a success and recommend it to people wishing to improve their fitness. The Pyramid Session provides a challenge from week to week and the exercises between the lengths make it a very demanding regime. I was pleased with the work that the exercises did and at the end of the 6 week program saw an improvement in my leg muscles, middle and upper body strength. I am extremely pleased with the improvement and success that the PEP has had.