Theoretical Prediction of Chiral 3D Hybrid Organic–Inorganic Perovskites

Hybrid organic–inorganic perovskites (HOIPs), in particular 3D HOIPs, have demonstrated remarkable properties, including ultralong charge‐carrier diffusion lengths, high dielectric constants, low trap densities, tunable absorption and emission wavelengths, strong spin–orbit coupling, and large Rashba splitting. These superior properties have generated intensive research interest in HOIPs for high‐performance optoelectronics and spintronics. Here, 3D hybrid organic–inorganic perovskites that implant chirality through introducing the chiral methylammonium cation are demonstrated. Based on structural optimization, phonon spectra, formation energy, and ab initio molecular dynamics simulations, it is found that the chirality of the chiral cations can be successfully transferred to the framework of 3D HOIPs, and the resulting 3D chiral HOIPs are both kinetically and thermodynamically stable. Combining chirality with the impressive optical, electrical, and spintronic properties of 3D perovskites, 3D chiral perovskites is of great interest in the fields of piezoelectricity, pyroelectricity, ferroelectricity, topological quantum engineering, circularly polarized optoelectronics, and spintronics.     

Nitrogen addition to iron powder by mechanical alloying

Nitrogen was alloyed into iron (a) by mechanical processing in a nitrogen gas environment, and (b) by mechanically alloying with iron-nitride powders to characterize resulting nano-structure and nitrogen distribution. Although the infused nitrogen concentration was significantly greater than the thermodynamic equilibrium solubility of iron, no nitrides formed, even for nitrogen concentrations as high as 4.1 wt.% However, a bctFe phase did form. Lattice expansion calculations indicate that the sum of the interstitial bcc-Fe and bctFe nitrogen concentrations was significantly less than the total measured nitrogen concentration. A considerable portion of the mechanically infused nitrogen was determined to be associated with nanograin boundaries.     

Randomized trial of breast self-examination in Shanghai: methodology and preliminary results

BACKGROUND: The efficacy of breast self-examination in helping to reduce mortality from breast cancer has not been rigorously demonstrated. PURPOSE: To assess efficacy, a large, randomized trial was initiated in Shanghai, China. METHODS: From October 1989 to October 1991, 267040 current and retired female employees associated with 520 factories in the Shanghai Textile Industry Bureau were randomly assigned on the basis of factory to either a self-examination instruction group (133375 women) or a control group (133665 women). The women were born within the period from 1925 through 1958. Women in the instruction group were given intensive training in breast self-examination, including the use of silicone breast models and personalized instruction, plus two subsequent reinforcement sessions and multiple reminders to practice the technique. Women in the control group were asked to attend training sessions on the prevention of low back pain. All women have been followed for the development of breast diseases and for death from breast cancer. RESULTS: A high level of participation during the first 4-5 years of the trial was documented among women in the instruction group. Randomly sampled women in this group demonstrated greater proficiency in detecting lumps in breast models than did randomly sampled women in the control group. Approximately equal numbers of breast cancers were detected in the two groups (331 in the instruction group and 322 in the control group) through 1994, which is the last year for which case-finding efforts have been completed. The breast cancers detected in the instruction group were not diagnosed at an appreciably earlier stage or smaller size than those in the control group. More benign breast lesions were detected in the instruction group than in the control group (1457 versus 623, respectively), suggesting a higher index of suspicion for women who received training. Cumulative breast cancer mortality rates through 5 years from entry into the study were nearly equivalent for the two groups. CONCLUSIONS: Breast self-examination has not led to a reduction in mortality from breast cancer in this study cohort in the first several years since the trial began. A shift toward the diagnosis of disease at a less advanced stage in women given instruction has also not been demonstrated. Longer follow-up of participants in this trial is required before final assessment can be made of the efficacy of breast self-examination. IMPLICATIONS: At this time, there is insufficient evidence to recommend for or against the teaching of breast self-examination.     

A behavioral probe of the growth of intake potential during the inter-meal interval in the rat.

The rat's willingness to ingest glucose after an initial intraoral intake test was probed by beginning a 2nd intraoral intake test at variable durations (1–220 min). In Exp 1, after an initial meal of 12.5% glucose solution averaging 26.9?±?1.7 ml, the size of the 2nd (probe) meal of the same stimulus increased linearly from 4.0?±?0.9 ml after a 1-min delay to 15.4?±?2.7 ml after a 120-min delay. In Exp 2, intraoral intake of a more concentrated (37.5%) glucose solution rose more slowly as a function of delay from 2.4?±?2.7 ml to 4.9?±?0.6 ml. For each glucose concentration, the linear recovery function and a slope that depends on stimulus concentration are consistent with a role for gastric emptying during the delay in intake recovery. In Exp 3, rats ingested 12.5% or 37.5% glucose to satiety in an initial test and received, after a variable delay, either the same or the other concentration as the probe stimulus. The same volumes were ingested at each delay whether the glucose concentration of the probe stimulus was the same or was switched from that presented in the initial test. This result shows that the taste and caloric properties of the probe stimulus played no role in determining how much of it would be ingested… (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of melt spinning on the microstructure and mechanical properties of three Ni-base superalloys

A microstructural and mechanical analysis was performed on three rapidly solidified nickel base superalloys. Transmission and scanning electron microscopy along with tensile tests were performed on the ribbons in the as-cast and aged condition. This investigation permitted a correlation to be made between cooling rate, microstructure, and mechanical properties. It was found that melt spinning significantly altered the physical characteristics of the alloys studied. The rapid cooling rates (∼10⁷ K/s) produced ribbons with a low dislocation density and small (∼1 μm) low angle cells. The precipitation of γ′ was suppressed, producing alloys with a smaller volume fraction of precipitates and lower APBE than in the conventionally cast condition. Also, the matrix/precipitate lattice mismatch was higher in the melt spun foils. Tensile strengths were similar to those in the conventional form; however, no measurable ductility was present. Aging the ribbons resulted in increases in γ′ volume fraction, tensile strengths, APBE, and elongations compared to the as-cast ribbons. The results of this work suggest that many of the microstructural refinements produced by melt spinning are lost after a short aging time at moderate temperatures.     

Behavioral preferences in response to social injustice: The effects of group permeability and social identity salience.

Examined features of an intergroup context that can affect people's preferred responses to a situation of social injustice. 90 undergraduates were randomly assigned to 1 of 3 conditions of group permeability (open, token, or closed) and 1 of 2 conditions of social identity salience (not salient or salient). It was predicted on the basis of social identity theory that individualistic responses would be preferred to a collective response when group boundaries were more open but not when they were closed. It was also expected that under conditions of group impermeability, collective behavior would be preferred to a greater extent by individuals for whom social identity was salient than by individuals for whom it was not salient. The results, which generally supported these hypotheses, are discussed in terms of social psychological theories of intergroup relations and also with regard to their potential practical implications. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

SPATIAL AND VISUAL REASONING: HUMANS VERSUS LOGIC

Glasgow's revival of the "imagery debate" in computational terms provides a renewed opportunity to review the role of logical reasoning in general problem solving. Of special interest is the long-standing distinction between analogical or depictive problem representations, and the more abstract linguistic forms typified by traditional formal logic syntax.
In our brief statement, we recall that logical reasoning rests on semantics not syntax, and that the concepts of soundness, completeness, and consistency are manifest in both depictive and linguistic representations. We emerge with two conclusions: (1) enduring confusion regarding computational aspects of the "imagery debate" arise from long-standing confusion regarding key logical concepts, and related notions such as epistemological versus heuristic adequacy, logical versus probabilistic independence, and direct versus indirect representations; (2) the desire for depictive reasoning methods is ultimately motivated by human needs, not computational needs.     

Enterprise architecture,IT effectiveness and the mediating role of IT alignment in US hospitals

Despite the possible benefits of implementing healthcare information technologies, successful implementation of effective healthcare information technology is constrained by cultural and regulatory concerns and technical obstacles encountered when establishing or upgrading an organisation's enterprise infrastructure. In this paper, we advance Ross' four‐stage model of enterprise architecture maturity as a valuable IT resource for helping healthcare organisations sustain a competitive advantage. We use partial least squares (PLS) structural equation modelling to analyse survey data from 164 US hospitals at different stages of EA maturity. Our results provide evidence that enterprise architecture maturity directly influences the effectiveness of hospitals' IT resources for achieving strategic goals. Further, enterprise architecture maturity indirectly influences the effectiveness of IT resources when IT alignment is incorporated as a mediating variable. We discuss the implications of our findings for research and practice and suggest opportunities for future research.     

Object-Oriented Systems Development

Object-oriented design is an approach to systems development that proposes the use of system objects to build new systems and rebuild old ones. An important goal of object-oriented development is to change the nature of traditional software development from designing and writing models from scratch to building systems through the assembly of reusable software objects. This article discusses the productivity potential as well as the limitations of object-oriented systems development and makes recommendations for its use.