Efficient web browsing with perfect anonymity using page prefetching

Anonymous web browsing is a hot topic with many potential applications for privacy reasons. The current dominant strategy to achieve anonymity is packet padding with dummy packets as cover traffic. However, this method introduces extra bandwidth cost and extra delay. Therefore, it is not practical for anonymous web browsing applications. In order to solve this problem, we propose to use the predicted web pages that users are going to access as the cover traffic rather than dummy packets. Moreover, we defined anonymity level as a metric to measure anonymity degrees, and established a mathematical model for anonymity systems, and transformed the anonymous communication problem into an optimization problem. As a result, users can find tradeoffs among anonymity level and cost. With the proposed model, we can describe and compare our proposal and the previous schemas in a theoretical style. The preliminary experiments on the real data set showed the huge potential of the proposed strategy in terms of resource saving.

Shear-free perfect fluids with a solenoidal electric curvature

We prove that the vorticity or the expansion vanishes for any shear-free perfect fluid solution of the Einstein field equations where the pressure satisfies a barotropic equation of state and the spatial divergence of the electric part of the Weyl tensor is zero.

Does practice make perfect? Results from a Chinese feasibility study of cognitive remediation in schizophrenia

Patients with schizophrenia often receive little by way of non-pharmacological interventions. Despite this, promising outcomes in programmes targeting cognitive deficits have been reported, suggesting that this is an area worthy of further investigation. The aim of the study was to implement and evaluate a brief computerised cognitive remediation programme designed to improve memory and attention in a male Chinese sample with chronic schizophrenia. Pre-testing was completed on a number of clinical and cognitive measures for intervention (n = 14) and treatment as usual (n = 17) participants. The intervention group then completed six weeks ( x no. of sessions = 12.78) of the computer-based cognitive remediation programme. Post-test measures for both groups were then collected again. Following the six week intervention, we found, contrary to our expectations, the intervention group improved on several of the clinical variables. The intervention group also performed better than the control group on the post-test measure of attention, but not verbal memory. These findings suggest that it is feasible to improve some aspects of cognitive abilities with a simple computerised training programme for people with serious mental illness.

Exploring Heideggerian hermeneutic phenomenology: a perfect fit for midwifery research

BACKGROUND: Heideggerian hermeneutic phenomenology has been used widely to understand the meaning of lived experiences in health research. For midwifery scholars this approach enables deep understanding of women's and midwives' lived experiences of specific phenomena. However, for beginning researchers this is not a methodology for the faint hearted. It requires a period of deep immersion to come to terms with at times impenetrable language and perplexing concepts. OBJECTIVES: This paper aims to assist midwives to untangle and examine some of the choices they face when they first come to terms with an understanding of this methodology and highlights the methodology's capacity to reveal midwifery authenticity and holistic practice. DISCUSSION: The illumination of a selection of various concepts underpinning hermeneutic phenomenology will inform midwives considering this methodology as suitable framework for exploring contemporary midwifery phenomena.

A notion of subgame perfect Nash equilibrium under knightian uncertainty

We define a subgame perfect Nash equilibrium under Knightian uncertainty for two players, by means of a recursive backward induction procedure. We prove an extension of the Zermelo-von Neumann-Kuhn Theorem for games of perfect information, i. e., that the recursive procedure generates a Nash equilibrium under uncertainty (Dow and Werlang(1994)) of the whole game. We apply the notion for two well known games: the chain store and the centipede. On the one hand, we show that subgame perfection under Knightian uncertainty explains the chain store paradox in a one shot version. On the other hand, we show that subgame perfection under uncertainty does not account for the leaving behavior observed in the centipede game. This is in contrast to Dow, Orioli and Werlang(1996) where we explain by means of Nash equilibria under uncertainty (but not subgame perfect) the experiments of McKelvey and Palfrey(1992). Finally, we show that there may be nontrivial subgame perfect equilibria under uncertainty in more complex extensive form games, as in the case of the finitely repeated prisoner's dilemma, which accounts for cooperation in early stages of the game.

A generalization of judds method of out-steady-state comparisons in perfect foresight models

We show that Judd (1982)’s method can be applied to any finite system, contrary to what he claimed in 1987. An example shows how to employ the technic to study monetary models in presence of capital accumulation.

A notion of subgame perfect nash equilibrium under knightian uncertainty

We define a subgame perfect Nash equilibrium under Knightian uncertainty for two players, by means of a recursive backward induction procedure. We prove an extension of the Zermelo-von Neumann-Kuhn Theorem for games of perfect information, i. e., that the recursive procedure generates a Nash equilibrium under uncertainty (Dow and Werlang(1994)) of the whole game. We apply the notion for two well known games: the chain store and the centipede. On the one hand, we show that subgame perfection under Knightian uncertainty explains the chain store paradox in a one shot version. On the other hand, we show that subgame perfection under uncertainty does not account for the leaving behavior observed in the centipede game. This is in contrast to Dow, Orioli and Werlang(1996) where we explain by means of Nash equilibria under uncertainty (but not subgame perfect) the experiments of McKelvey and Palfrey(1992). Finally, we show that there may be nontrivial subgame perfect equilibria under uncertainty in more complex extensive form games, as in the case of the finitely repeated prisoner's dilemma, which accounts for cooperation in early stages of the game .

Accelerating solutions of perfect fluid hydrodynamics for initial energy density and life-time measurements in heavy ion collisions

A new class of accelerating, exact, explicit and simple solutions of relativistic hydrodynamics is presented. Since these new solutions yield a finite rapidity distribution, they lead to an advanced estimate of the initial energy density and life-time of high energy heavy ion collisions. Accelerating solutions are also given for spherical expansions in arbitrary number of spatial dimensions.

On the construction of perfect codes from HEX signal constellations

Recently, minimum and non-minimum delay perfect codes were proposed for any channel of dimension n. Their construction appears in the literature as a subset of cyclic division algebras over Q(zeta(3)) only for the dimension n = 2(s)n(1), where s is an element of {0,1}, n(1) is odd and the signal constellations are isomorphic to Z[zeta(3)](n) In this work, we propose an innovative methodology to extend the construction of minimum and non-minimum delay perfect codes as a subset of cyclic division algebras over Q(zeta(3)), where the signal constellations are isomorphic to the hexagonal A(2)(n)-rotated lattice, for any channel of any dimension n such that gcd(n,3) = 1. (C) 2012 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.

Bell's locality condition confronting perfect anti-correlations

We show that Local Realistic Theories, defined as obeying the Bells's locality condition, cannot satisfy the prefect anti-correlations without at the same time maximally violating rotational symmetry at the hidden variable level. We examine whether the rotational symmetry can be restored after the statistical average. We also comment on the question whether such theories are necessarily deterministic at the hidden variable leva. © 1999 Elsevier Science B.V. All rights reserved.

Construction of perfect space-time codes

In this work, we propose an innovative methodology to extend the construction of minimum and non-minimum delay perfect codes as a subset of cyclic division algebras over ℚ(ζ3), where the signal constellations are isomorphic to the hexagonal An 2 -rotated lattice, for any channel of any dimension n such that gcd{n, 3) = 1.