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Test anxiety is known to negatively affect test performance. Having students write about their testing worries before taking a test was recently shown to improve test performance by reducing test anxiety. We conducted a controlled study to replicate this result in the context of students using online Computer Science tutors unsupervised and on their own time. Instead of using open-ended expressive...
System integrity can be put at risk by unintentional transitivity of resource access. We present a natural deduction calculus for an access control model with an explicit trust function on resources. Its inference relation is designed to limit unintentionally transitive access from untrusted parties. We also offer results for ordered cut and normalization related to security and hint at a prototype...
As digital resources increasingly growing and the economic benefit of digital intellectual property rights being increasingly important, people has been increasingly emphasis on information security issues brought by the data remnants in storage devices. They try their best to prevent the potential risks. In this paper, we survey comprehensively related technologies, standards and trends of erasure,...
Kocarev gave the first cryptosystems based on the semi-group property of Chebyshev polynomials, which seemed excellent but actually insecure. Due to the inherent periodicity of trigonometric function, an attack can easily get plaintext given ciphertext. In this paper, we extend Chebyshev polynomials from real number to finite fields to avoid the attack and present the corresponding key exchange scheme,...
The UNICORE grid system provides a seamless, secure and intuitive access to distributed grid resources. In recent years, UNICORE 5 is used as a well-tested grid middleware system in production grids (e.g. DEISA, D-Grid) and at many supercomputer centers world-wide. Beyond this production usage, UNICORE serves as a solid basis in many European and International research projects and business scenarios...
A principal factor in sensor network design is energy efficiency. In this work, we propose to extend the lifetime of sensor networks using appropriate choice of sensor node distribution. The key idea of our scheme is to deploy more nodes in areas of extensive energy usage. Using this scheme of sensor node distribution, we use probabilistic angular routing to route data packets from the sensor nodes...
It is becoming increasingly difficult to implement effective systems for preventing network attacks, due to the combination of (1) the rising sophistication of attacks requiring more complex analysis to detect, (2) the relentless growth in the volume of network traffic that we must analyze, and, critically, (3) the failure in recent years for uniprocessor performance to sustain the exponential gains...
An algorithm is given for the multi-writer version of the Concurrent Reading While Writing (CRWW) problem. The algorithm solves the problem of allowing simultaneous access to arbitrarily sized shared data without requiring waiting, and hence avoids mutual exclusion. This. demonstrates that a quite complicated concurrent control problem can be solved-without eliminating the efficiency of parallelism...
This paper addresses the problem of how to adapt an algorithm designed for fixed topology networks to produce the intended results, when run in a network whose topology changes dynamically, in spite of encountering topological changes during its execution. We present a simple and unified procedure, called a reset procedure, which, when combined with the static algorithm, achieves this adaptation....
The contribution of this paper is two-fold. First, we describe two ways to construct multivalued atomic n-writer n-reader registers. The first solution uses atomic 1-writer 1-reader registers and unbounded tags. the other solution uses atomic 1-writer n-reader registers and bounded tags. The second part of the paper develops a general methodology to prove atomicity, by identifying a set of criteria...
Reaching agreement is a primitive of distributed computing. While this poses no problem in an ideal, failure-free environment, it imposes certain constraints on the capabilities of an actual system: a system is viable only if it permits the existence of consensus protocols tolerant to some number of failures. Fischer, Lynch and Paterson [FLP] have shown that in a completely asynchronous model, even...
We present a cryptographic protocol allowing two mutually distrusting parties, A and B, each having a secret bit, to "simultaneously" exchange the values of those bits. It is assumed that initially each party presents a correct encryption of his secret bit to the other party. We develop a new tool to implement our protocol: a slightly biased symmetric coin. The key property of this coin...
The problem of implementing mutual exclusion of N asynchronous parallel processes in a model where the primitive communication mechanism is a test-and-set operation on a shared variable, was the subject of extensive research. While a two-valued variable suffices to insure mutual exclusion, it is shown in [1] that N/2 values are necessary to avoid lockout of any process, and N + 1 values are required...
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