Network security under siege: the timing attack

Although most encryption algorithms are theoretically secure and remain impervious to even the most sophisticated cryptanalytic techniques, new attacks like the timing attack exploit the engineering side of network security. A timing attack is basically a way of deciphering a user's private key information by measuring the time it takes to carry out cryptographic operations. Factors such as branching and conditional statements, RAM cache hits, processor instructions that run in nonfixed time, as well as performance optimizations to bypass unnecessary operations, all contribute to predictability and therefore to the probability of key decryption     

Bidirectional associative plasticity of unitary CA3-CA1 EPSPs in the rat hippocampus in vitro

Associative long-term potentiation (LTP) and depression of compound and unitary CA3-CA excitatory postsynaptic potentials (EPSPs) were investigated in rat hippocampal slice cultures. The induction of LTP with synchronous pairing of synaptic activation and postsynaptic depolarization resulted in an increase in the amplitude of EPSPs to the same absolute level, regardless of whether the input was naive or had been previously depressed by asynchronous pairing of pre- and postsynaptic activity. Saturated LTP of compound and unitary EPSPs was reversed by asynchronous pairing and could be reinduced by synchronous pairing. The likelihood that an action potential in a presynaptic CA3 cell failed to trigger an unitary EPSP in a postsynaptic CA1 cell decreased after induction of associative potentiation and increased after induction of associative depotentiation. These changes in the rate of transmission failures were accompanied by large changes in the amplitude of nonfailure EPSPs. We conclude that the same CA3-CA1 synapses can alternatively undergo associative potentiation and depression, perhaps through opposite changes in a single expression mechanism.     

Accuracy of MMPI-based inferences regarding memory and concentration in closed-head-trauma patients.

This study examined the validity of MMPI scores and MMPI-based cognitive complaints as indicators of memory and concentrational disturbances in 70 closed-head-trauma patients. The relation of scores on the MMPI Depression (D), Schizophrenia (Sc), Mental Dullness (D4), Lack of Ego Mastery, Cognitive (Sc2A), and Organic Symptoms (Org) scales to actual memory performance on the WAIS—R Digit Span and Wechsler Memory Scale (Russell's revision) subtests was explored. The results suggest an absence of any relation between actual memory performance on any of these subtests and MMPI scores or a Cognitive Complaint Index consisting of 8 MMPI items. Findings are discussed in light of the questionable validity of memory complaints in other samples, as well as possible limitations in the ecological validity of current tests of memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Design and performance of cryogenic enclosures for long duration testing of large samples

We have designed a large helium dewar as part of an experiment to investigate gravitational radiation. Two such dewars have been constructed. Our use requires a nonmagnetic dewar to cool an aluminium antenna of approximately 5000 kg to below helium temperatures and to keep the antenna in a stable low temperature environment for extended time. This requires a low temperature volume of 1.5 m inner diameter and 3.1 m length and a cooling system capable of efficiently removing the room temperature enthalpy of 8.5 × 10⁸ J. Our solution to this problem is of wider application than simply gravity wave detection so we have discussed the design philosophy in some detail. As constructed, the apparatus uses less than 1 l of helium per hour when cold.     

Flavonoid glycosides and hydroxycinnamic acid esters of blackcurrants (Ribes nigrum). Phenolics of fruits 9

The major flavonol glycosides of ripe blackcurrants (Ribes nigrum cv. Silvergieters Schwarze), myricetin 3-beta-D-glucopyranoside, rutin, and isoquercitrin, have been isolated in crystalline form. Analysis by thin-layer chromatography confirmed the occurrence of the 3-rutinosides and 3-glucosides of cyanidin and delphinidin. No free flavonoid aglycones could, however, be detected in the fresh berries. The major constituent fluorescing blue under ultraviolet light on paper and cellulose thin-layer chromatograms, was isolated and characterized as 1-O-caffeyl-beta-D-glucopyranose. Also isolated were 1-O-ferulyl- and 1-O-p-coumaryl-beta-D-glucopyranose. The occurrence fo hydroxycinnamyl-D-glucoses in blackcurrants does not appear to have been recognized previously.     

Public versus private expectancy of success: Confidence booster or performance pressure?

In Exp I, private expectancies of success were manipulated by having 38 male and 26 female undergraduates complete a confidential preliminary test that was rigged to cause either success or failure. Ss furnished confidential self-reports of expectancies and were informed that their audience expected them to succeed in an anagram-solving task. Results show that Ss' private expectancies of success improved performance, while audience's expectations of success lowered performance. Findings were strongest for Ss low in trait self-consciousness and for males. In Exp II, 30 undergraduates completed a personality questionnaire and were told they had an integration score of 75. Ss were (1) told they were expected to do well on the basis of past research findings, (2) told they were expected to do well on the basis of the experimenter's theory, or (3) given no information about expectations. Results show that Condition 1 raised performance while Condition 2 lowered performance. Findings fit a model holding that audience expectations of success constitute performance pressure that harms performance except when substantial private confidence is created. (24 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Molar pregnancy in British Columbia: estimated incidence and postevacuation regression patterns of the beta subunit of human chorionic gonadotropin

A total of 171 cases of molar pregnancy were followed by serial radioimmunoassay of the beta subunit of human chorionic gonadotropin (hCG-beta) over a 4-year period. The incidence over the study interval was 1:1,202 pregnancies in the province. In 120 women with intact uteri and measurable plasma levels of hCG-beta at the initiation of follow-up, the hormone remained detectable for up to 219 days (between 31 and 32 weeks) following evacuation, with 50% of patients remaining positive at 63 days (between 8 and 9 weeks). In five women undergoing hysterectomy, the hormone remained detectable for up to 112 days (between 15 and 16 weeks) postoperatively. In 92% of the cases, hCG-beta regressed to negative without chemotherapy. The prolonged presence of hCG in plasma after evacuation of the mole, regardless of the presence or absence of the uterus, points to persistence of molar tissue and its gradual rejection from uterine and extrauterine sites as a common phenomenon in the natural history of the uncomplicated postmolar course of this disease.