Aharonov-Bohm effect in monolayer black phosphorus (phosphorene) nanorings

This work presents theoretical demonstration of Aharonov-Bohm (AB) effect in monolayer phosphorene nanorings (PNR). Atomistic quantum transport simulations of PNR are employed to investigate the impact of multiple modulation sources on the sample conductance. In presence of a perpendicular magnetic field, we find that the conductance of both armchair and zigzag PNR oscillate periodically in a low-energy window as a manifestation of the AB effect. Our numerical results have revealed a giant magnetoresistance (MR) in zigzag PNR (with a maximum magnitude approaching two thousand percent). It is attributed to the AB effect induced destructive interference phase in a wide energy range below the bottom of the second subband. We also demonstrate that PNR conductance is highly anisotropic, offering an additional way to modulate MR. The giant MR in PNR is maintained at room temperature in the presence of thermal broadening effect.Comment: 7 pages, 7 figure

Electric-field switching of exciton spin splitting in coupled quantum dots

We investigate theoretically the spin splitting of the exciton states in semiconductor coupled quantum dots (CQDs) containing a single magnetic ion. We find that the spin splitting can be switched on/off in the CQDs \textit{via} the \textit{sp-d}exchange interaction using the electric field. An interesting bright-to-dark exciton transition can be found and significantly affects the photoluminescence spectrum. This phenonmenon is induced by the transition of the ground exciton state, arising from the hole mixing effect, between the bonding and antibonding states.Comment: 3 pages, 5 figures. to appear in Appl. Phys. Let

Normalized solutions for some quasilinear elliptic equation with critical Sobolev exponent

Consider the equation \begin{equation*} -\Delta_p u =\lambda |u|^{p-2}u+\mu|u|^{q-2}u+|u|^{p^\ast-2}u\ \ {\rm in}\ \R^N \end{equation*} under the normalized constraint $$\int_{ \R^N}|u|^p=c^p,$$ where $-\Delta_pu={\rm div} (|\nabla u|^{p-2}\nabla u)$, $1<p<N$, $p0$ and $\lambda\in\R$. In the purely $L^p$-subcritical case, we obtain the existence of ground state solution by virtue of truncation technique, and obtain multiplicity of normalized solutions. In the purely $L^p$-critical and supercritical case, we drive the existence of positive ground state solution, respectively. Finally, we investigate the asymptotic behavior of ground state solutions obtained above as $\mu\to0^+$

Review on The Research of Online Reviews’ Perceived Credibility

Online review has become one of the most important references for modern consumers to purchase products or service. Based on combing the related literature on credibility of internet public opinions, this paper gives a summary of influence factors of perceived credibility of online reviews through three aspects: the credibility of source, the credibility of channel and the credibility of information. From the angle of online reviews information structure characteristics (including additional reviews vs. one-time reviews), this paper aims to discuss which one has higher perceived credibility, and information quality adjust the differences in perceived credibility

MMSE-optimal approximation of continuous-phase modulated signal as superposition of linearly modulated pulses

The optimal linear modulation approximation of any M-ary continuous-phase modulated (CPM) signal under the minimum mean-square error (MMSE) criterion is presented in this paper. With the introduction of the MMSE signal component, an M-ary CPM signal is exactly represented as the superposition of a finite number of MMSE incremental pulses, resulting in the novel switched linear modulation CPM signal models. Then, the MMSE incremental pulse is further decomposed into a finite number of MMSE pulse-amplitude modulated (PAM) pulses, so that an M-ary CPM signal is alternatively expressed as the superposition of a finite number of MMSE PAM components, similar to the Laurent representation. Advantageously, these MMSE PAM components are mutually independent for any modulation index. The optimal CPM signal approximation using lower order MMSE incremental pulses, or alternatively, using a small number of MMSE PAM pulses, is also made possible, since the approximation error is minimized in the MMSE sense. Finally, examples of the MMSE-optimal CPM signal approximation and its comparison with the Laurent approximation approach are given using raised-cosine frequency-pulse CPM schemes

Bank risk and performance in an emerging market setting: the case of Bangladesh

Purpose – This study aims to investigate the impacts of bank capital requirements on the performance and risk of the emerging economy, i.e. Bangladeshi banking sector. Design/methodology/approach – The study applies an unbalanced panel data which comprises 30 banks yielding a total of 413 bank-year observations over the period 2000 to 2015. Findings – Using generalized methods of moments, the empirical results of this research reveal that bank capital is positively and significantly impressive on bank performance, whereas negatively and significantly impact on risk. The study also finds the inverse relationship between risk and performance in both the performance and risk equations. The results also indicate that there is a persistence of performance and risk from one year to the next year. Originality/value – This is the unique investigation on Bangladeshi bank industry that considers the simultaneous effect of bank capital requirements on risk and performance. Therefore, it is predicted that the empirical evidence of this research shows policy implications to the regulatory authority of Bangladeshi banking industry to determine relevant policies.Objetivo - Este estudio tiene como objetivo investigar los impactos de los requisitos de capital bancario sobre el desempeño y el riesgo de la economía emergente, es decir, el sector bancario de Bangladesh. Diseño / metodología / enfoque - El estudio aplica un panel de datos no balanceado que comprende 30 bancos que arrojan un total de 413 observaciones de año bancario durante el período 2000 a 2015. Recomendaciones - Utilizando métodos generalizados de momentos, los resultados empíricos de esta investigación revelan que el capital bancario es positiva y significativamente impresionante en el desempeño bancario, mientras que tiene un impacto negativo y significativo en el riesgo. El estudio también encuentra la relación inversa entre riesgo y desempeño tanto en las ecuaciones de desempeño como de riesgo. Los resultados también indican que existe una persistencia de desempeño y riesgo de un año al siguiente. Originalidad / valor - Esta es la investigación única sobre la industria bancaria de Bangladesh que considera el efecto simultáneo de los requisitos de capital bancario sobre el riesgo y el rendimiento. Por lo tanto, se predice que la evidencia empírica de esta investigación muestra implicaciones políticas para la autoridad reguladora de la industria bancaria de Bangladesh para determinar las políticas relevantes

A molecular mechanism for environmental sex determination

Daphnia produce genetically identical males and females; their sex is determined by environmental conditions. Recently, Kato et al. identified isoform switching events in Daphnia as a gene regulatory mechanism for sex-specific development. This finding uncovers the impact of alternative usage of gene isoforms on this extreme phenotypic plasticity trait.</p

Syphilis among middle-aged female sex workers in China: a three-site cross-sectional study.

ObjectivesThis study addresses the lack of empirical studies about the epidemic of syphilis among middle-aged female sex workers (FSWs). The objectives of this study were to investigate prevalence of syphilis, and its potential risk factors among middle-aged FSWs in China.DesignA cross-sectional study with respondent-driven sampling (RDS).SettingA multisite study conducted at three Chinese cites (Nanning, Hefei, and Qingdao) with different levels of sexually transmitted diseases in 2014.Participants1245 middle-aged female sex workers who were over 35 years old (about 400 per study site).Main outcome measuresUnprotected commercial sex, and syphilis and HIV infection were biologically tested and measured.ResultsThe RDS-adjusted prevalence of active syphilis was 17.3% in Hefei, 9.9% in Qingdao, and 5.4% in Nanning. The RDS-adjusted prevalence of prevalent syphilis was between 6.8% and 33.6% in the three cities. The proportion of unprotected sex in the past 48 h verified by the prostate-specific antigen test (PSA) was between 27.8% and 42.4%. Multiple log-binomial regression analyses indicate that middle-aged FSWs who had 5 or more clients in the past week prior to interviews and engaged in unprotected sex were more likely to be active syphilitic cases. Middle-aged FSWs who had rural residency were less likely to be active syphilitic cases.ConclusionsIn contrast with previous studies that reported low prevalence of syphilis and high prevalence of protected sex among FSWs in China, both the prevalence of syphilis and unprotected sex were high among middle-aged FSWs. Evidence-based intervention programmes should be developed and evaluated among this vulnerable population in China and other countries with similar settings