Calculations of intersection cross-slip activation energies in fcc metals using nudged elastic band method

The nudged elastic band (NEB) method is used to evaluate activation energies for dislocation intersection cross-slip in face-centered cubic (fcc) nickel and copper, to extend our prior work which used an approximate method. In this work we also extend the study by including Hirth locks (HL) in addition to Lomer–Cottrell locks and glide locks (GL). Using atomistic (molecular statics) simulations with embedded atom potentials we evaluated the activation barrier for a dislocation to transform from fully residing on the glide plane to fully residing on the cross-slip plane when intersecting a 120° forest dislocation in both Ni and Cu. The initial separation between the screw and the intersecting dislocation on the (1 1 1) glide plane is varied to find a minimum in the activation energy. The NEB method gives energies that are ∼10% lower than those reported in our prior work. It is estimated that the activation energies for cross-slip from the fully glide plane state to the partially cross-slipped state at the 120° intersection forming GL in Ni and Cu are ∼0.47 and ∼0.65 eV, respectively, and from the fully cross-slip plane state to the partially cross-slipped state forming LC are ∼0.68 and ∼0.67 eV. The activation energies for cross-slip from the fully glide plane state to the partially cross-slipped state at the 120° intersection forming HL in Ni and Cu are estimated to be ∼0.09 and ∼0.31 eV, respectively. These values are a factor of 3–20 lower than the activation energy for bulk cross-slip in Ni and, a factor of 2–6 lower than the activation energy for cross-slip in Cu estimated by Friedel–Escaig analysis. These results suggest that cross-slip should nucleate preferentially at selected screw dislocation intersections in fcc materials and the activation energies for such mechanisms are also a function of stacking fault energy.     

Cloning of a carboxyl-terminal isoform of the prostanoid FP receptor

An FP prostanoid receptor isoform, which appears to arise from alternative mRNA splicing, has been cloned from a mid-cycle ovine large cell corpus luteum library. The isoform, named the FP(B) receptor, is identical to the original isoform, the FP(A), throughout the seven transmembrane domains, but diverges nine amino acids into the carboxyl terminus. In contrast to FP(A), whose carboxyl terminus continues for another 46 amino acids beyond the nine shared residues, the FP(B) terminates after only one amino acid. The FP(A) isoform appears to arise by the failure to utilize a potential splice site, while a 3.2-kilobase pair intron is spliced out from the FP gene to generate the FP(B) isoform mRNA. The two isoforms have indistinguishable radioligand binding properties, but seem to differ in functional coupling to phosphatidylinositol hydrolysis. Thus, in COS-7 cells transiently transfected with either the FP(A) or the FP(B) receptor cDNAs, prostaglandin F(2alpha) stimulates inositol phosphate accumulation to the same absolute maximum, but the basal level of inositol phosphate accumulation is approximately 1.3-fold higher in cells transfected with the FP(B) as compared with cells transfected with the FP(A) isoform. Using the polymerase chain reaction, mRNA encoding the FP(B) isoform was identified in the ovine corpus luteum.     

Rapid word learning in 13- and 18-month-olds.

A number of theorists have argued that the productive naming explosion results from advances in abilities that underlie language learning (e.g., the realization that words are symbols, changes in conceptual structure, or the onset of word learning constraints). If any of these accounts are accurate, there should be parallel developments in comprehension. To explore this issue, 4 studies assessed whether pre- and postnaming explosion children differ in their ability to learn a new word after limited exposure. 13- and 18-mo-olds heard a new object label just 9 times in a 5-min training session and then their comprehension was assessed in a multiple-choice procedure. Under favorable testing conditions, both 18- and 13-mo-olds showed comprehension of the new word, even after a 24-hr delay. These results suggest that well before the productive naming explosion, children can learn a new object label quickly. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Health beliefs and compliance with mammography-screening recommendations in asymptomatic women.

The utility of the health belief model (HBM) for predicting compliance with the American Cancer Society recommendations for mammography screening over and above demographics, knowledge, physician input, and objective risk for breast cancer was assessed. In all, 615 predominantly middle-class White women (aged 35–92 yrs) were surveyed from 1987 to 1989. A multiple indicator measurement model of the HBM constructs of perceived susceptibility, severity, benefits, and barriers was verified with confirmatory factor analysis. Physician input alone accounted for 25% of the variance in compliance, and HBM constructs alone, 16%. HBM constructs accounted for 7% additional variance in compliance beyond all other predictors and thus may be a fruitful focus for interventions to increase screening rates. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An MMPI comparison of polydrug and heroin abusers.

Researchers recently have resurrected the relevance of the addiction-prone personality hypothesis for explaining drug abuse by faulting previous studies for failing to control non-drug-related S background characteristics. This notion was tested by comparing MMPI clinical and content scores of 122 polydrug and 132 heroin abusers under conditions in which covariates were controlled and not controlled. The covariates age, education, socioeconomic status, and admission status interacted significantly but did not change results. Polydrug abusers consistently scored higher than heroin users on clinical scales, but differences for multivariate ANOVAs and analyses of covariance were either not significant or not large enough to be clinically meaningful. The variety of personality types found for both heroin and polydrug abusers is interpreted as refuting the notion that one personality type is addiction-prone. Contributions of personality to drug abuse remain suspected but as yet unspecified. (6 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

消除共模电压的放大器

有史以来(或至少是有精密电子以来),模拟设计者最头痛的问题之一就是CMV(共模电压)带来的误差,或称之为可怕的地回路.尽管恐惧冲击着工程师们的心灵,但CMV并没有什么特别神秘之处.CMV误差的产生原因很简单:不同位置上电路的公共电压基准(即:地),如一个机箱的传感器和另一个机箱的ADC,两个基准电位是不同的.     

Mobilising opposition: The campaign against housing action trusts in Tower Hamlets

This paper examines tenant opposition to the British government's plans for Housing Action Trusts (HATs), using material drawn from a case study of the tenants' anti‐HAT campaign in the London Borough of Tower Hamlets. After examining the HAT plans, the reasons for tenant objections to the privatisation of their council estates are explained. The political discourse of the anti‐HAT campaign is examined in order to assess the strategies by which support amongst tenants on both the affected estates, and in the borough as a whole, was mobilised. Strategies of resistance to the HATs were negotiated within the campaign through a constant process of discussion and debate about the purposes of the campaign and the construction of arguments against the policy. Central themes to emerge included a justification of the principles behind the provision of council housing; parallels that could be drawn between the HATs and the London Docklands Development Corporation; the notion that only tenant power could defeat the HATS; and arguments linking local experiences of the ‘housing crisis’ to the HATs and the government's housing policies more generally. The experience of this campaign underlines the necessity for potential divisions in such campaigns to be minimised in order to mobilise support and achieve their objectives.     

Visual attention modulates signal detectability.

The mechanism by which visual–spatial attention affects the detection of faint signals has been the subject of considerable debate. It is well known that spatial cuing speeds signal detection. This may imply that attentional cuing modulates the processing of sensory information during detection or, alternatively, that cuing acts to create decision bias favoring input at the cued location. These possibilities were evaluated in 3 spatial cuing experiments, with a total of 22 university students. Peripheral cues were used in Exp 1, and central cues were used in Exps 2 and 3. Cuing similarly enhanced measured sensitivity, P(A) and d′, for simple luminance detection in all 3 experiments. Under some conditions it also induced shifts in decision criteria (beta). These findings indicate that visual–spatial attention facilitates the processing of sensory input during detection either by increasing sensory gain for inputs at cued locations or by prioritizing the processing of cued inputs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)