4,765 research outputs found
Two-Dimensional Dirac Fermions Protected by Space-Time Inversion Symmetry in Black Phosphorus
We report the realization of novel symmetry-protected Dirac fermions in a
surface-doped two-dimensional (2D) semiconductor, black phosphorus. The widely
tunable band gap of black phosphorus by the surface Stark effect is employed to
achieve a surprisingly large band inversion up to ~0.6 eV. High-resolution
angle-resolved photoemission spectra directly reveal the pair creation of Dirac
points and their moving along the axis of the glide-mirror symmetry. Unlike
graphene, the Dirac point of black phosphorus is stable, as protected by
spacetime inversion symmetry, even in the presence of spin-orbit coupling. Our
results establish black phosphorus in the inverted regime as a simple model
system of 2D symmetry-protected (topological) Dirac semimetals, offering an
unprecedented opportunity for the discovery of 2D Weyl semimetals
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Effect of pitavastatin on erythrocyte membrane fatty acid content in patients with chronic kidney disease: two-arm parallel randomized controlled trial.
BACKGROUND: Statins reduce the risk of cardiovascular events in patients with chronic kidney disease (CKD). Although diabetes mellitus (DM) is a reported side effect of statin treatment, some studies have indicated that pitavastatin does not cause DM. The present study investigated the effect of pitavastatin on the fatty acid (FA) content of erythrocyte membranes, which affects the occurrence of DM and cardiovascular diseases. In addition, changes in adiponectin and glycated hemoglobin (HbA1c) levels were evaluated after pitavastatin treatment. METHODS: A total of 45 patients were enrolled, 28 of whom completed the study. Over 24 weeks, 16 patients received 2 mg pitavastatin and 12 patients received 10 mg atorvastatin. Dosages were adjusted after 12 weeks if additional lipid control was required. There were 10 and nine patients with DM in the pitavastatin and atorvastatin groups, respectively. Erythrocyte membrane FAs and adiponectin levels were measured using gas chromatography and enzyme-linked immunosorbent assay, respectively. RESULTS: In both groups, saturated FAs, palmitic acid, trans-oleic acid, total cholesterol, and low-density lipoprotein cholesterol levels were significantly lower than those at baseline. The arachidonic acid (AA) content in the erythrocyte membrane increased significantly in the pitavastatin group, but adiponectin levels were unaffected. HbA1c levels decreased in patients treated with pitavastatin. No adverse effects were associated with statin treatment. CONCLUSION: Pitavastatin treatment in patients with CKD may improve glucose metabolism by altering erythrocyte membrane AA levels. In addition, pitavastatin did not adversely affect glucose control in patients with CKD and DM
Structural, electrical and multiferroic properties of Nb-doped Bi7Fe3Ti3O21 thin films
The effects of donor Nb5+-ion doping on the structural, electrical, and multiferroic properties of an Aurivillius Bi7Fe3Ti3O21 thin film were investigated. Incorporation of Nb5+-ions into the Ti4+-sites of the Bi7Fe3Ti3O21 thin film resulted in a substantial improvement of its electrical and multiferroic properties. From the study of the electrical properties, the Bi7Fe3Ti2.94Nb0.06O21+δ thin film exhibited a low leakage current density of 5.11×10-6 A/cm2at 100 kV/cm, which was about one order of magnitude lower than that of the untreated Bi7Fe3Ti3O21 thin film. The ferroelectric P -E hysteresis loops of the Bi7Fe3Ti2.94Nb0.06O21+δthin film showed a large remnant polarization (2Pr) of 20.6 μC/cm2 at 630 kV/cm whereas the 2Pr value measured for the untreated Bi7Fe3Ti3O21 thin film was 3.5 μC/cm2at 318 kV/cm. Furthermore, a well-saturated magnetic hysteresis loop with an enhanced magnetization was observed for the Bi7Fe3Ti2.94Nb0.06O21+ δthin film at room temperature
The EPOCH Project: I. Periodic variable stars in the EROS-2 LMC database
The EPOCH (EROS-2 periodic variable star classification using machine
learning) project aims to detect periodic variable stars in the EROS-2 light
curve database. In this paper, we present the first result of the
classification of periodic variable stars in the EROS-2 LMC database. To
classify these variables, we first built a training set by compiling known
variables in the Large Magellanic Cloud area from the OGLE and MACHO surveys.
We crossmatched these variables with the EROS-2 sources and extracted 22
variability features from 28 392 light curves of the corresponding EROS-2
sources. We then used the random forest method to classify the EROS-2 sources
in the training set. We designed the model to separate not only Scuti
stars, RR Lyraes, Cepheids, eclipsing binaries, and long-period variables, the
superclasses, but also their subclasses, such as RRab, RRc, RRd, and RRe for RR
Lyraes, and similarly for the other variable types. The model trained using
only the superclasses shows 99% recall and precision, while the model trained
on all subclasses shows 87% recall and precision. We applied the trained model
to the entire EROS-2 LMC database, which contains about 29 million sources, and
found 117 234 periodic variable candidates. Out of these 117 234 periodic
variables, 55 285 have not been discovered by either OGLE or MACHO variability
studies. This set comprises 1 906 Scuti stars, 6 607 RR Lyraes, 638
Cepheids, 178 Type II Cepheids, 34 562 eclipsing binaries, and 11 394
long-period variables. A catalog of these EROS-2 LMC periodic variable stars
will be available online at http://stardb.yonsei.ac.kr and at the CDS website
(http://vizier.u-strasbg.fr/viz-bin/VizieR).Comment: 18 pages, 20 figures, suggseted language-editing by the A&A editorial
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Design of Web-based Security Management for Intrusion Detection
Electronic business is rapidly popularized and extended through Internet. Internet has many security weaknesses, so we need the security solution such Intrusion Detection System that minimizes the damage of hacking and responds the intrusion dynamically. It is difficult for legacy management system to process the security environments and electronic business, because legacy system lacks of security policies and integrated security methods. In order to resolve these problems, we need security management system that has standard security policy, consulting, diagnosis, maintenance, and repair function. In this paper, we design and implement Web-based security management for intrusion detection. Our security system consists of network nodes, general hosts and a management node. A management node manages a network node, that is a secure router, and general hosts by security policies. We design the channel between the management node and the network node using IPsec (IP Security). We have applied java and Web to implementing user interface of security system. As the proposed system makes use of Web, security management system is easily accessed through the Web
Effects of Nd-doping on the structural, electrical, and multiferroic properties of Bi7Fe3Ti3O21 thin films
Aurivillius-phase six-layered Bi7Fe3Ti3O21 (BFTO21) and Nd-doped Bi6.4Nd0.6Fe3Ti3O21 (BNdFTO21) thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method in order to investigate their structural, electrical, and multiferroic properties. Doping the Bi sites of the BFTO21 with Nd-ions led to remarkable improvements in the electrical and the multiferroic properties. The electrical study of the BNdFTO21 thin film showed a low leakage current density of 4.38 × 10-6 A/cm at an applied electric field of 100 kV/cm, which was about one order of magnitude lower than that of the BFTO21 thin film. The ferroelectric P - E hysteresis loop of the BNdFTO21 thin film exhibited a large remnant polarization (2Pr) of 24 μC/cm2 and a low coercive electric field (2Ec) of 154 kV/cm at an applied electric field of 239 kV/cm. Furthermore, the magnetization and the coercive magnetic field that were observed for the BNdFTO21 thin film at room temperature were drastically enhanced compared to those observed for the BFTO21 thin film
Detecting Variability in Massive Astronomical Time-series Data. II. Variable Candidates in the Northern Sky Variability Survey
We present variability analysis of data from the Northern Sky Variability Survey (NSVS). Using the clustering method, which defines variable candidates as outliers from large clusters, we cluster 16,189,040 light curves having data points at more than 15 epochs as variable and non-variable candidates in 638 NSVS fields. Variable candidates are selected depending on how strongly they are separated from the largest cluster and how rarely they are grouped together in eight-dimensional space spanned by variability indices. All NSVS light curves are also cross-correlated with IRAS , AKARI, Two Micron All Sky Survey, Sloan Digital Sky Survey (SDSS), and GALEX objects, as well as known objects in the SIMBAD database. The variability analysis and cross-correlation results are provided in a public online database, which can be used to select interesting objects for further investigation. Adopting conservative selection criteria for variable candidates, we find about 1.8 million light curves as possible variable candidates in the NSVS data, corresponding to about 10% of our entire NSVS sample. Multi-wavelength colors help us find specific types of variability among the variable candidates. Moreover, we also use morphological classification from other surveys such as SDSS to suppress spurious cases caused by blending objects or extended sources due to the low angular resolution of the NSVS.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98631/1/1538-3881_143_3_65.pd
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