An experimental study on Γ\Gamma(2) modular symmetry in the quantum Hall system with a small spin-splitting

Magnetic-field-induced phase transitions were studied with a two-dimensional electron AlGaAs/GaAs system. The temperature-driven flow diagram shows the features of the $\Gamma$(2) modular symmetry, which includes distorted flowlines and shiftted critical point. The deviation of the critical conductivities is attributed to a small but resolved spin splitting, which reduces the symmetry in Landau quantization. [B. P. Dolan, Phys. Rev. B 62, 10278.] Universal scaling is found under the reduction of the modular symmetry. It is also shown that the Hall conductivity could still be governed by the scaling law when the semicircle law and the scaling on the longitudinal conductivity are invalid. *corresponding author:[email protected]: The revised manuscript has been published in J. Phys.: Condens. Matte

Scaled outdoor experimental studies of urban thermal environment in street canyon models with various aspect ratios and thermal storage

Street aspect ratios and urban thermal storage largely determine the thermal environment in cities. By performing scaled outdoor measurements in summer of 2017 in Guangzhou, China, we investigate these impacts on spatial/temporal characteristics of urban thermal environment which are still unclear so far. Two types of street canyon models are investigated, i.e. the ‘hollow’ model resembling hollow concrete buildings and the ‘sand’ model consisting of buildings filled with sand attaining much greater thermal storage. For each model, three street aspect ratios (building height/street width, H/W = 1, 2, 3; H = 1.2 m) are considered. The diurnal variations of air-wall surface temperatures are observed and their characteristics are quantified for various cases. The daily average temperature and daily temperature range (DTR) of wall temperature vary significantly with different aspect ratios and thermal storage. During the daytime, wider street canyon (H/W = 1) with less shading area experiences higher temperature than narrower ones (H/W = 2, 3) as more solar radiation received by wall surfaces. At night, wider street canyon cools down quicker due to stronger upward longwave radiation and night ventilation. For hollow models, H/W = 1 attains DTR of 12.1 °C, which is 1.2 and 2.1 °C larger than that of H/W = 2, 3. Moreover, the sand models experience smaller DTR and a less changing rate of wall temperature than hollow models because larger thermal storage absorbs more heat in the daytime and releases more at night. DTR of hollow models with H/W = 1, 2, 3 is 4.5, 4.6 and 3.8 °C greater than sand models respectively. For both hollow and sand models, wider streets experience a little higher daily average temperature (0.3–0.6 °C) than narrower ones. Our study provides direct evidence in how man-made urban structures influence urban climate and also suggests the possibility to control outdoor thermal environment by optimize urban morphology and thermal storage

Deformations of the hemisphere that increase scalar curvature

Consider a compact Riemannian manifold M of dimension n whose boundary \partial M is totally geodesic and is isometric to the standard sphere S^{n-1}. A natural conjecture of Min-Oo asserts that if the scalar curvature of M is at least n(n-1), then M is isometric to the hemisphere S_+^n equipped with its standard metric. This conjecture is inspired by the positive mass theorem in general relativity, and has been verified in many special cases. In this paper, we construct counterexamples to Min-Oo's conjecture in dimension n \geq 3.Comment: Revised version, to appear in Invent. Mat

Rigidity of compact Riemannian spin Manifolds with Boundary

In this article, we prove new rigidity results for compact Riemannian spin manifolds with boundary whose scalar curvature is bounded from below by a non-positive constant. In particular, we obtain generalizations of a result of Hang-Wang \cite{hangwang1} based on a conjecture of Schroeder and Strake \cite{schroeder}.Comment: English version of "G\'eom\'etrie spinorielle extrins\`eque et rigidit\'es", Corollary 6 in Section 3 added, to appear in Letters Math. Phy

Students' satisfaction using e-learning as a supplementary tool

E-learning is useful to help students gaining digital and data literacy during their studies particularly in the era of Industrial Revolution 4.0 (IR 4.0). E-learning which is characterized by time and place flexibility should be utilized as a tool for self-learning. In Universiti Teknologi Malaysia (UTM), elearning plays an important role as a supplementary tool for effective web-based learning. The purpose of this study is to examine what are the factors that drive students' satisfaction in e-learning. A total of 194 samples were collected from undergraduate students in UTM using quantitative method. Purposive sampling technique was used to select the respondents. Statistical Package for the Social Sciences (SPSS) was utilized for data analysis. The findings showed that delivery method and content have a positive and significant relationship with satisfaction of using e-learning. However, system operations has no impact on students' satisfaction in e-learning. In conclusion, the finding of this study is expected to provide an effective teaching model for general education schools

Reworking research: interactions in academic articles and blogs

The blog is an increasingly familiar newcomer to the panoply of academic genres, offering researchers the opportunity to disseminate their work to new and wider audiences of experts and interested lay people. This digital medium, however, also brings challenges to writers in the form of a relatively unpredictable readership and the potential for immediate, public and potentially hostile criticism. To understand how academics in the social sciences respond to this novel rhetorical situation, we explore how they discoursally recontextualise in blogs the scientific information they have recently published in journal articles. Based on two corpora of 30 blog posts and 30 journal articles with the same authors and topics, we examine the ways researchers carefully reconstruct a different writer persona and relationship with their readers using stance and engagement (Hyland, 2005). In addition to supporting the view that the academic blog is a hybrid genre situated between academic and journalistic writing, we show how writers’ rhetorical choices help define different rhetorical contexts

Socio-demographic and physical factors associated with disability in adults with non-specific chronic neck pain

While socio-demographic, physical and other factors are associated with neck pain, there is scanty literature about how these factors are associated with disability in adults suffering from this condition. We aimed to determine the socio-demographic and physical (strength and range of motions) related factors of disability in adults with non-specific chronic neck pain. A total of 34 adults with neck pain, with mean age 55 (10.80) years from a physiotherapy clinic in a teaching hospital participated in this study. Socio-demographic details such as body mass index (BMI), current employment status, hours of exercise done a week were obtained. Severity of pain was evaluated using the Numerical Rating Scale (NRS). Disability level was assessed using Neck Disability Index. Cervical range of motion was measured using the Cervical Range of Motion device. A hand dynamometer was used to measure the dominant hand grip muscle strength. The data was analyzed using descriptive and stepwise linear regression analysis. More than half the participants were females, above 50 years, in the overweight group (BMI>25 kg/m2 ), currently unemployed and had severe neck pain (NRS >7). Handgrip strength was the only factor found to be significantly (p<0.05) related to neck disability. The results from our study suggest that improving general muscle conditioning and strength are important in preventing neck disability among adults with non-specific neck pain

Nuclear Stopping as A Probe to In-medium Nucleon-nucleon Cross Section in Intermediate Energy Heavy Ion Collisions

Using an isospin-dependent quantum molecular dynamics, nuclear stopping in intermediate heavy ion collisions has been studied. The calculation has been done for colliding systems with different neutron-proton ratios in beam energy ranging from 15MeV/u to 150MeV/u. It is found that, in the energy region from above Fermi energy to 150MeV/u, nuclear stopping is very sensitive to the isospin dependence of in-medium nucleon-nucleon cross section, but insensitive to symmetry potential. From this investigation, we propose that nuclear stopping can be used as a new probe to extract the information on the isospin dependence of in-medium nucleon-nucleon cross section in intermediate energy heavy ion collisions

Comparison of two dengue NS1 rapid tests for sensitivity, specificity and relationship to viraemia and antibody responses

<p>Abstract</p> <p>Background</p> <p>Dengue is a major public health problem in tropical and subtropical countries. Rapid and easy diagnosis of dengue can assist patient triage and care-management. The detection of DENV NS1 on rapid lateral flow tests offers a fast route to a presumptive dengue diagnosis but careful evaluations are urgently needed as more and more people use them.</p> <p>Methods</p> <p>The sensitivity and specificity of the Bio-Rad NS1 Ag Strip and SD Dengue Duo (NS1/IgM/IgG) lateral flow rapid tests were evaluated in a panel of plasma samples from 245 Vietnamese patients with RT-PCR confirmed dengue and 47 with other febrile illnesses.</p> <p>Results</p> <p>The NS1 rapid tests had similar diagnostic sensitivities (respectively 61.6% and 62.4%) in confirmed dengue cases but were 100% specific. When IgM/IgG results from the SD Dengue Duo were included in the test interpretation, the sensitivity improved significantly from 62.4% with NS1 alone to 75.5% when NS1 and/or IgM was positive and 83.7% when NS1 and/or IgM and/or IgG was positive. Both NS1 assays were significantly more sensitive for primary than secondary dengue. NS1 positivity was associated with the underlying viraemia as NS1-positive samples had a significantly higher viraemia than NS1-negative samples.</p> <p>Conclusions</p> <p>These data suggest that the NS1 test component of these assays are highly specific and have similar levels of sensitivity. The IgM parameter in the SD Duo test improved overall test sensitivity without compromising specificity. The SD Dengue Duo lateral flow rapid test deserves further prospective evaluation in dengue endemic settings.</p