Possible aggregation biases in road safety research and a mechanism approach to accident modeling

In accident reconstruction, individual road accidents are treated as essentially deterministic events, although incomplete information can leave one uncertain about how exactly an accident happened. In statistical studies, on the other hand, accidents are treated as individually random, although the parameters governing their probability distributions may be modeled deterministically. Here, a simple deterministic model of a vehicle/pedestrian encounter is used to illustrate how naïvely applying statistical methods to aggregated data could lead to an ecological fallacy and to Simpson’s paradox. It is suggested that these problems occur because the statistical regularities observed in accident data have no independent status, but are simply the result of aggregating particular types and frequencies of mechanisms.     

Children with down syndrome: Implications for assessment and intervention in the school.

Down syndrome is the most common genetic cause of mental retardation and one of the most frequently occurring neurodevelopmental genetic disorders in children. Children with Down syndrome typically experience a constellation of symptomology that includes developmental motor and language delay, specific deficits in verbal memory, and broad cognitive deficits. Children with Down syndrome are also at increased risk of medical problems, which can exacerbate their cognitive deficits. Although the diagnosis of Down syndrome is facilitated by cytogenetic testing and the unique physical phenotype, the development of proper interventions for this group of children is less obvious. Despite their functional deficits, children with Down syndrome possess relative strengths, which can be the focus of interventions. This article reviews the etiology and developmental course of Down syndrome, appraises examples of empirically validated interventions, and discusses neurocognitive processing issues that should be considered during a psychoeducational evaluation for intervention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lesions of the amygdala, but not of the cerebellum or red nucleus, block conditioned fear as measured with the potentiated startle paradigm.

In Exp I, 97 male Sprague-Dawley albino rats were given 10 light–shock pairings on 2 successive days. At 24–48 hrs following training, groups of Ss received bilateral transection of the cerebellar peduncles, bilateral lesions of the red nucleus (which receives most of the cerebellar efferents), or bilateral lesions of the central nucleus of the amygdala. Controls were sham operated. At 3–4 days after surgery, Ss were tested for potentiated startle (PS [increased acoustic startle in the presence of the light previously paired with shock]). PS was blocked by lesions of the central nucleus of the amygdala but not by transection of the cerebellar peduncles or lesions of the red nucleus. Exp II, in which a visual prepulse test was used with 14 Ss, indicated that the blockade of PS observed in Ss with amygdala lesions could not be attributed to optic tract damage. Exp III, with 20 Ss, demonstrated that the absence of potentiation in Ss with amygdala lesions was not simply due to a lowered startle level ceiling, because these Ss could show increased startle with increased stimulus intensity and with administration of intraperitoneal strychnine, (0.75 mg/kg), a drug that increases startle. Results are consistent with the hypothesis that the amygdala is involved in fear conditioning. (64 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Habituation, prepulse inhibition, fear conditioning, and drug modulation of the acoustically elicited pinna reflex in rats.

A reliable component of the acoustic startle response in animals is a flexion of the ears, the pinna reflex (PR). The present investigation attempted to develop a preparation and apparatus suitable for analyzing the PR in the awake rat. A 2nd goal was to examine the PR under behavioral and pharmacological conditions known to affect other response systems, such as whole-body startle, and determine whether the PR is a valid model for analyzing behavioral plasticity. The amplitude of the PR in 17 spinally transected male Sprague-Dawley rats was directly related to stimulus intensity and exhibited short-term habituation, prepulse inhibition, and enhancement by prior fear conditioning. PR amplitude increased following intraperitoneal administration of strychnine HCl (0.75 mg/kg) and was decreased following clonidine HCl (40 μg/kg). It is concluded that this preparation and response system are valid for studying various forms of behavioral modification. Findings are discussed in terms of the potential utility of this response system in investigating the cellular correlates of behavioral plasticity in mammals. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Biological psychology's relationships to psychology and neuroscience.

Biological psychology originally had a central role in psychology, but many psychologists who perform research traditionally done within the realm of biological psychology are shifting to the new discipline of neuroscience. We document this shift by showing that biological psychologists have a larger relative representation in the Society for Neuroscience (SN) than in the American Psychological Association (APA). They make up the third largest group within the SN, and psychology has the single largest departmental representation among SN student members. Investigations assessing behavior are reported at annual meetings of the SN and in the Society's official journal at a level consistent with psychologists' representation in the Society. A survey of graduate students training in biological psychology shows a strong affiliation with the discipline of neuroscience. These students indicate a greater likelihood of joining the SN than the APA; they believe the SN better represents their individual interests and the discipline of biological psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

High-power etched-facet lasers

We demonstrate, for the first time, laser diodes with anetched facet fabricated by chemically assisted ion beametching, producing 1?7 W pulsed and 470mW CW output power from one facet. The devices were coated and bonded junction-side-up and tested at room temperature. The single 40 ?m stripe, 300 ?m-long devices exhibit 94 mA threshold current and differential quantum efficiencies of 80% pulsed (78% CW).     

The Influence of Segregation of Mn on the Recrystallization Behavior of C-Mn Steels

Metallurgical and Materials Transactions B - The influence of Mn segregation that occurs during casting on recrystallization kinetics has been explored for a C-Mn automotive steel. A homogenization...