Search

We analyze the spin-dependent conductance spectrum of a double quantum dot with Rashba spin-orbit and electron-electron interactions based on the Keldysh nonequilibrium Green's function formalism. A clear physical picture emerges from the single-particle analysis of electron-transfer pathways in a quantum dot molecule. It provides an insight into the mechanism that underlies the evolution of bonding resonances. This study demonstrates both numerically and analytically that the mechanism of quantum interference is altered, as either component of the Rashba spin-orbit interaction is modulated. Most importantly, the bonding state can be controlled by tuning the Rashba parameter: a bound state in the continuum becomes unbound upon gate control and vice versa, mediated by the transverse Rashba spin-orbit component. A spin-polarized current is shown to be produced by the interplay of the spin-resolved interference effect with the magnetic flux. Sharp spin polarization that arises from the negative differential conductance, observed over a wide range of values of relevant parameters, is discussed. [ABSTRACT FROM AUTHOR]

Patients harboring arteriovenous malformations (AVMs) may present with focal neurological deficit, seizures, hemorrhage or be completely asymptomatic. This diversity in manifestation of AVM is related to the individual characteristics of AVMs such as size, location, configuration of feeding arteries, and drainage veins. Treating the AVMs with high flow fistula and downstream sinuses occlusion is challenging. The authors reported their experience of treating this kind of AVM. The high venous pressure caused diffuse cortical venous regurgitation and engorgement of left superior ophthalmic vein and symptoms resembling carotid venous fistula. To avoid possible reflux of embolization materials to cortical veins and facilitate surgical treatment, the bilateral transverse sinuses were re canalized first. The venous pressure was measured through left transverse sinus, and it decreased significantly from 50 mmHg to 20 mmHg after bilateral sinus stenting. The AVM was then embolized and excised uneventfully. [ABSTRACT FROM AUTHOR]

A spin interferometer utilizing the Rashba effect is proposed. The novel design is composed of a 1-D straight wire and a 1-D half-ring. By calculating the norm of the superposed wave function, we derive analytical expressions to describe the spin interference spectrum as a function of the Rashba coupling strength. Presented spin interference results are identified to include i) the quantum-mechanical 4π rotation effect, ii) the geometric effect, and iii) the Shubnikov-de Haas-like beating effect. [ABSTRACT FROM AUTHOR]

We report on the analysis of quantum transport through an Aharonov-Bohm ring with embedded double quantum dots. The normal metal leads are assumed to be weakly coupled to the two quantum dots. In the quantum dot region, Rashba spin-orbit coupling and electron-electron interaction are considered. The quantum transport is analyzed based on the Keldysh nonequilibrium Green's function formalism. A spin-polarized current emerges in this device due to the combined effect of a magnetic flux, threading through the AB ring, and the Rashba spin-orbit coupling. An interesting switching property of the spin polarization by turning on and off the gate within small voltage window is observed. This feature, however, does not exist in the Aharonov-Bohm ring structure with single quantum dot. We therefore propose a theoretical idea of a bipolar spin polarization switch. [ABSTRACT FROM AUTHOR]

Science and technology are driving people's life changes, including education and the environment. Many scholars have attempted to import technology into the classroom to help students learn in different subjects. However, students often need assistance with unfamiliar learning approaches and learning environments. This study proposed a non‐immersive virtual reality (VR) guidance system combined with a two‐tier strategy to help students learn geology knowledge. Two groups of students used different learning approaches: the experimental group students were guided by the two‐tier test VR guidance system, and the control group students learned with the conventional VR guidance system. According to the experimental result, the two‐tier test VR guidance system not only improved the students' learning achievement in natural science, but also enhanced their learning motivation. In addition, according to the sequential results, we found that VR learning materials or environmental resources can help students answer questions and solve problems more effectively. [ABSTRACT FROM AUTHOR]

Particulate lead (Pb) is a primary air pollutant that affects society because of its health impacts. This study investigates the source sectors of Pb associated with ambient fine particulate matter (PM2.5) over central-western Taiwan (CWT) with new constraints on the Pb-isotopic composition. We demonstrate that the contribution of coal-fired facilities is overwhelming, which is estimated to reach 35 ± 16% in the summertime and is enhanced to 57 ± 24% during the winter monsoon seasons. Moreover, fossil-fuel vehicles remain a major source of atmospheric Pb, which accounts for 12 ± 5%, despite the current absence of a leaded gasoline supply. Significant seasonal and geographical variations in the Pb-isotopic composition are revealed, which suggest that the impact of East Asian (EA) pollution outflows is important in north CWT and drastically declines toward the south. We estimate the average contribution of EA outflows as accounting for 35 ± 15% (3.6 ± 1.5 ng/m3) of the atmospheric Pb loading in CWT during the winter monsoon seasons. [ABSTRACT FROM AUTHOR]

Abstract: Template-free, one step formation of Cu(In, Ga)Se2 (CIGS) nanotip arrays (NTRs) to enhance device efficiency were discussed. Through Ar+ ion milling process, the CIGS NTRs could be formed directly on the CIGS layer. The angles and lengths of CIGS NTRs could be precisely controlled by incident angle of Ar+ beam and milling time, respectively. Mechanisms were proposed to be a self-masking effect by Cu segregation formed at early stage confirmed by Transmission Electron Microscopy, Grazing Incidence X-ray Diffraction, Energy Dispersive Spectroscopy, and Auger Electron Spectroscopy. Measurements of devices on various KCN washing time and thickness of CdS buffer layer were reported to achieve the highest efficiency of CIGS NTRs devices. This approach provides one-step fast process without templates, easy integration with in-line sputtering process, and no post-selenizatoin process for the formation of CIGS nanostructure, which can stimulate great attention not only in academic investigations but also in industrial side for practical applications. [Copyright &y& Elsevier]

Recently, we reported that diploid sequence type (DST) 140 was a predominant type of Candida tropicalisamong isolates with fluconazole minimum inhibitory concentrations (MICs) ≥64 μg/ml collected in the Taiwan Surveillance of Antimicrobial Resistance of Yeasts (TSARY) in 1999. To determine if DST140 persists in Taiwan, we have used multilocus sequence typing to characterize the genetic profiles of 31 resistant isolates (MICs ≥64 μg/ml), together with 19 susceptible isolates (MICs ≤16 μg/ml) collected in TSARY 2006. Among the 50 isolates, 33 distinct DSTs were detected. Of the 31 resistant isolates, 11 (35.5%) belonged to two closely related DSTs (140 and 98), whereas none of the 19 susceptible isolates did (p= 0.004). The isolates belonging to DST140 and 98 were from different geographic regions instead of a restricted area. Thus, our data show temporal and spatial transmission of C. tropicalisclones with high fluconazole MICs in Taiwan from 1999 to 2006. [ABSTRACT FROM AUTHOR]

Neisseria gonorrhoeae infection is the second major cause of sexually transmitted diseases worldwide. Development of resistance to multiple classes of antimicrobials in N. gonorrhoeae has compromised treatm and disease control. Herein, we report the availability of the draft genome sequence of a muitidrug-resista N. gonorrhoeae isolate, TCDC-NG08107, which spread in groups of men who have sex with men (MSM) Taiwan. [ABSTRACT FROM AUTHOR]