海洛因成瘾者的脑灰质密度下降

本研究对海洛因成瘾者（n=34）和无毒品依赖的正常被试（n=34）进行磁共振脑结构扫描,用基于体素的形态学测量（VBM）方法分析被试间灰质密度的差异,并考察了海洛因成瘾者用药时间与灰质密度之间的关系。结果表明,同正常对照组相比,海洛因成瘾者其额叶和颞叶下部的灰质密度显著下降。进一步分析显示,用药时间短于5年的成瘾者其灰质密度下降不明显,而用药时间5年以上的患者其灰质密度下降非常显著。本文讨论了上述结果的潜在临床价值和理论意义。     

USING FIXED‐TIME SCHEDULES TO MAINTAIN BEHAVIOR: A PRELIMINARY INVESTIGATION

The purpose of this study was to evaluate the potential of fixed‐time (FT) schedules to maintain behavior. Two children who had been diagnosed with autism were taught a functional task. Subsequently, three different FT schedules (i.e., yoked, thin, dense) were compared to determine their capacity to maintain task responding. Results suggested that FT schedules may be used to maintain previously acquired behavior.     

Aggressive behavior in a confined troop of Japanese macaques: Effects of density,season, and gender

A troop of Japanese macaques (Macaca fuscata) confined in a 2-acre outdoor corral increased from 107 to 192 individuals during the 5-year tenure of a project that assessed the effects of density, season, and gender on the expression of adult aggressive behavior. Two statistical subgroups of 16 males and 28 females that were adults at the start of the project and that survived until its completion were studied intensively. There were significant season and sex differences in all groups: males were much more aggressive than females, and males were most aggressive during the fall and and winter mating season; females were most aggressive during the spring and summer birth season. Only the 16 adult males increased their frequency of aggressive behavior as the population density increased. This increase was due to the greater number of potential antagonists available each year.     

三数值加工系统假说：数值加工机制新探

数值加工的机制是数量认知领域的核心科学问题之一。三数值加工系统假说从新的角度阐释了各种数值加工机制的关系, 它认为认知系统通过三种不同的机制来快速分析非符号刺激的数值：感数(subitizing)机制精确地分析1~4个刺激的数值; 数量(numerosity)机制分析密度适中的刺激点阵的数量, 加工误差正比于被分析的数量, 符合韦伯定律; 当刺激的密度超出一定范围时, 密度(density)机制通过分析刺激密度来推断刺激的数量关系, 加工误差正比于被加工数值的平方根。一系列研究证实, 这三种数值加工机制具有不同的行为规律和脑电特征。未来研究需要探讨数量机制是否分别与感数机制、密度机制存在平行激活, 从而阐明三种数值加工机制的作用关系。     

Phonological neighbourhood effects in French spoken-word recognition

According to activation-based models of spoken-word recognition, words with many and high-frequency phonological neighbours are processed more slowly than words with few and low-frequency phonological neighbours. Although considerable empirical support for inhibitory neighbourhood density effects has accumulated, especially in English, little or nothing is known about the effects of neighbourhood frequency and its interaction with neighbourhood density. In this study we examine both effects first separately and then simultaneously in French lexical decision experiments. As in English, we found that words in dense neighbourhoods are recognized more slowly than words in sparse neighbourhoods. Moreover, we showed that words with higher frequency neighbours are processed more slowly than words with no higher frequency neighbours, but only for words occurring in sparse neighbourhoods. Implications of these results for spoken-word recognition models are discussed.     

Making the uncontrollable seem controllable: The role of action in the illusion of control

It is well known that certain variables can bias judgements about the perceived contingency between an action and an outcome, making them depart from the normative predictions. For instance, previous studies have proven that the activity level or probability of responding, P(R), is a crucial variable that can affect these judgements in objectively noncontingent situations. A possible account for the P(R) effect is based on the differential exposure to actual contingencies during the training phase, which is in turn presumably produced by individual differences in participants' P(R). The current two experiments replicate the P(R) effect in a free-response paradigm, and show that participants' judgements are better predicted by P(R) than by the actual contingency to which they expose themselves. Besides, both experiments converge with previous empirical data, showing a persistent bias that does not vanish as training proceeds. These findings contrast with the preasymptotic and transitory effect predicted by several theoretical models.     

Intersections Between Nativity, Ethnic Density, and Neighborhood SES: Using an Ethnic Enclave Framework to Explore Variation in Puerto Ricans’ Physical Health

Although past research has demonstrated a “health disadvantage” for Puerto Rican adults, very little is known about correlates of health among this group. Given Puerto Ricans’ unique experiences of migration and settlement, an ethnic enclave framework that integrates nativity, ethnic density, and neighborhood SES may offer insight into factors influencing Puerto Ricans’ health. This study uses a sample of 449 adult mainland- and island-born Puerto Ricans living in New York City and Chicago. The data, collected as a part of the MIDUS Survey of Minority Groups, are stratified by neighborhood ethnic density and neighborhood SES, allowing for the examination of the individual and joint influences of neighborhood characteristics on physical health. Results revealed that ethnic density and neighborhood SES were not independently or interactively related to physical health for mainland-born Puerto Ricans. However, the interaction between ethnic density and neighborhood SES was related to self-reported health, functional limitations, and health symptoms for island-born Puerto Ricans. Island-born Puerto Ricans living in ethnically dense, low SES neighborhoods reported worse health than island-born Puerto Ricans living in other types of neighborhoods. This may be a result of isolation from resources both within and outside the neighborhood.     

Early effects of neighborhood density and phonotactic probability of spoken words on event-related potentials

All current models of spoken word recognition propose that sound-based representations of spoken words compete with, or inhibit, one another during recognition. In addition, certain models propose that higher probability sublexical units facilitate recognition under certain circumstances. Two experiments were conducted examining ERPs to spoken words and nonwords simultaneously varying in phonotactic probability and neighborhood density. Results showed that the amplitude of the P2 potential was greater for high probability-density words and nonwords, suggesting an early inhibitory effect of neighborhood density. In order to closely examine the role of phonotactic probability, effects of initial phoneme frequency were also examined. The latency of the P2 potential was shorter for words with high initial-consonant probability, suggesting a facilitative effect of phonotactic probability. The current results are consistent with findings from previous studies using reaction time and eye-tracking paradigms and provide new insights into the time-course of lexical and sublexical activation and competition.     

A Dual Process Model of Attitudes towards Immigration: Person × Residential Area Effects in a National Sample

This research took a person × situation approach to predicting prejudice by looking at how social worldviews interact with real‐world environmental factors to predict how people respond to immigrants within their local area. Taking a Dual Process Motivational approach, we hypothesized that a higher proportion of immigrants in the local community would be associated with negative attitudes toward immigration for respondents high in dangerous world beliefs. Conversely, we hypothesized that living in a highly affluent (as opposed to socioeconomically deprived) community would be associated with negative attitudes toward immigration for respondents high in competitive world beliefs. Both hypotheses were supported using regional information derived from national census data combined with representative survey data from a large telephone sample conducted in New Zealand (N = 6,489). These findings support the proposition that individual differences interact with specific features of the environment to predict people's levels of prejudice in distinct ways.     

Toward an understanding of aging in plutonium from direct measurements of stored energy

ABSTRACT

We present here the first direct measurement of the radiation-damage-induced energy stored in δ-phase plutonium. The primary mode of radioactive decay of ²³⁹Pu occurs with a time constant of τ=1.1?×?10¹²?s. Each decay imparts about 85?keV of recoil energy to the uranium byproduct, 5.2?Mev to the alpha particle, and a spectrum of mostly low energy gamma rays with the most probable at 51?keV [1]. Most of the decay energy is converted immediately to heat, releasing about 1.9?mW/g. However, some thermally-recoverable energy remains trapped. Reported here are measurements of that stored energy using differential scanning calorimetry (DSC) applied to ²³⁹Pu-2.0 at.%Ga δ-phase alloy. Retained energy of ～2 J/g saturates at about 5 months and is unchanged after 30 years. The magnitude of the stored energy agrees with a short-bond defect model that that we present here. This model treats radiation damage as a Pu impurity with shortened bond lengths. It explains the change in known properties with age and predicts that density increases with age, contrary to current thinking. The short-bond impurities proposed are expected to act like other impurities, affecting strength, phase transitions, grain boundaries and other metallurgical properties.