Veselago lensing in graphene with a p-n junction: classical versus quantum effects

The feasibility of Veselago lensing in graphene with a p-n junction is investigated numerically for realistic injection leads. Two different set-ups with two narrow leads are considered with absorbing or reflecting side edges. This allows us to separately determine the influence of scattering on electron focusing for the edges and the p-n interface. Both semiclassical and tight-binding simulations show a distinctive peak in the transmission probability that is attributed to the Veselago lensing effect. We investigate the robustness of this peak on the width of the injector, the position of the p-n interface and different gate potential profiles. Furthermore, the influence of scattering by both short- and long-range impurities is considered.Comment: 10 pages, 7 figure

AM Happy Scale: Reliability and Validity of a Single-Item Measure of Happiness

Research on happiness has been abundant over the last few decades and findings have repeatedly shown that people who are happier have better life outcomes in terms of health and in nearly all other aspects of functioning. Thus, it is crucial to continue studying the construct using valid and reliable measurements. Single-item rating scales have been shown to be psychometrically sound and more convenient in comparison to multiple-item measures designed to measure certain constructs. The aim of the present study was to test the reliability and convergent and divergent validity of a single-item happiness scale, the Aréchiga-Moldovan Happy Scale (AM Happy Scale). Participants included 275 adults between the ages of 64 to 81 (M = 71.51, SD = 3.85; 63.6% female; 77.1% White, 10.5% Hispanic, 6.2% Black, and 4.7% Asian) recruited from Loma Linda, California and the surrounding communities. This population was chosen due to progressive increases in life expectancy and rates of older adults in the workforce that highlight the importance of prevention and maintenance of health. The overall range for the minimum reliability estimate of the AM Happy Scale was .27 to 1.06. The AM Happy Scale showed a convergent relationship with the Positive Affect subscale of the Positive and Negative Affect Schedule (PANAS; rs = .57, p \u3c .001) and the Spirituality Index of Well-Being (rs = .50, p \u3c .001). The AM Happy Scale showed a divergent relationship with the Negative Affect subscale of the PANAS (rs = -.38, p \u3c .001) and the Patient Health Questionnaire (rs = -.42, p \u3c .001). Additionally, the AM Happy Scale also demonstrated a positive relationship with the 12-item Short-Form Health Survey, a measure of mental (rs = .51, p \u3c .001) and physical health (rs = .26, p \u3c .001). Findings from this study have serious clinical implications indicating that a brief measure of happiness may be a quick and efficient way to assess an individual’s overall sense of well-being, which is also associated with his or her physical health

Appearance-Related Commentary and Body Image in Women

Research has shown that sociocultural factors such as interpersonal appearance-related commentary influence body dissatisfaction and disordered eating. Few studies have investigated the effects of appearance-related commentary among undergraduate women of different ethnic groups. The aims of the current study were to examine: (1) ethnic differences in body dissatisfaction, eating disorder psychopathology, sociocultural attitudes towards appearance, appearance-related commentary, and acculturation to Western culture in African-, European-, and Hispanic Americans; and (2) negative appearance-related commentary and acculturation to Western culture as moderators of the relationship between body dissatisfaction and eating disorder psychopathology. Participants included 345 undergraduate women (Mage = 19.17, SD = 1.48; 47.5% European American, 23.8% African American, and 13.6% Hispanic American). Results indicated that European American women reported higher levels of sociocultural attitudes towards appearance and greater negative effects as a result of receiving negative weight and shape-related commentary than African American women. Hispanic American women reported greater negative effects as a result of receiving positive weight and shape-related commentary in comparison to European American women. There were positive associations between the negative effects of receiving positive commentary and reported levels of body dissatisfaction and eating disorder psychopathology in African- and European American women. In European- and Hispanic American women, higher levels of acculturation were associated with fewer negative effects as a result of receiving positive commentary. Negative weight and shape-related commentary and acculturation were not significant moderators of the relationship between body dissatisfaction and eating disorder psychopathology in all three ethnic groups. Results suggest that the three groups of women have similar levels of body image and eating disorder psychopathology. However, European Americans reported higher levels of sociocultural attitudes and greater negative effects of receiving negative weight and shape-related commentary, which may place this group at higher risk for eating disorder psychopathology. Findings from this study increase our understanding of the potential effects of appearance-related commentary and the role of acculturation on perceptions of commentary among different groups. In addition, such findings may be used to inform interventions for body image and eating disturbance in ethnic groups

Low Temperature Susceptibility of the Noncentrosymmetric Superconductor CePt_3Si

We report ac susceptibility measurements of polycrystalline CePt_3Si down to 60 mK and in applied fields up to 9 T. In zero field, a full Meissner state emerges at temperatures T/Tc < 0.3, where Tc=0.65 K is the onset transition temperature. Though transport measurements show a relatively high upper critical field Bc2 ~ 4-5 T, the low temperature susceptibility, \chi', is quite fragile to applied field, with \chi' diminishing rapidly in fields of a few kG. Interestingly, the field dependence of \chi' is well described by the power law, 4\pi\chi'=(B/B_c)^{1/2}, where Bc is the field at which the onset of resistance is observed in transport measurements.Comment: 5 figure

Does economic policy uncertainty impact inflation?

Using the monthly economic policy uncertainty (EPU) index of Baker et al. (2016), we examine its impact on inflation rate in the UK over the period from 1998 to 2020. We adopt a vector autoregressive (VAR) model and generate impulse response functions. To ensure that the identified shocks will be uncorrelated, based on economic theoretical considerations, we employed Cholesky restrictions. The results show that a positive innovation in EPU index leads to a weakening of the real exchange rate and unemployment rate and at the same time a rise in inflation rate. The broad implication of the present research is that under economic policy uncertainty shocks, inflation and unemployment rate respond in accordance with the effects described by the economic theory and the Phillips curve, which emphasizes that there is a trade-off between inflation and unemployment.info:eu-repo/semantics/publishedVersio

Present status and preliminary results of the VLF/LF radio recording European network installed in 2009.

In January 2009 a European network of receivers able to measure the electric field intensity from various VLF/LF broadcasting stations located throughout Europe, was installed. Five new receivers constructed by an Italian enterprise have been delivered to Greece, Romania, Turkey and to the Italian team. The motivation of this effort is to study the possible connections between the preparatory phase of earthquakes and perturbations in the transmitted radio signals. The receivers can be reached via ftp and gsm mobile connection, thus allowing a real time data collection. We present here the status of the network and the various testing steps performed in order to achieve a correct set up. We show how antennas variations, receivers locations and changes of selected frequencies affect the performances of the whole network. After this necessary testing period, several LF/VLF radio signals are now simultaneously and continuously being sampled by the five receivers. As a preliminary result we inspect also specific cases in which an anomaly in the radio signals is clearly related to the transmitter or to the receiver (e.g. meteorological conditions around the sampling site). At a basic level, the analysis adopted consists in a simple statistical evaluation of the signals by comparing the instantaneous values to the trend of the signal

Direct determination of Pb isotope ratios in archaeological materials by coupling liquid chromatography to multicollector ICP-MS

A procedure for the determination of Pb isotope ratios by coupling liquid chromatography to a multicollector ICP-MS has been developed. The procedure allows the direct injection of samples after dissolution without resorting to time-consuming off-line separation procedures. The separation of Pb from concomitant elements is carried out by anionic exchange as ethylenediamine tetraacetic acid (EDTA) chelates using EDTA and ammonium nitrate as a mobile phase. A flow injection system allows the injection of NIST 981 Pb isotopic standard, before and after the Pb peak from the sample, and the on-line addition of Tl for mass bias correction and bracketing. The procedure was validated by injecting NIST 981 into the chromatographic system and by comparing the results for real samples with the classical off-line separation procedure using Pb spec resins. The optimised procedure was applied to archaeological samples containing different concentrations of Pb. It was observed that the only limitation to the accuracy of the procedure was the concentration of Pb in the samples as no preconcentration is performed. Solid archaeological samples containing at least 500 μg g−1 of Pb can be studied using the proposed procedure