837 research outputs found
High Field Magneto-Conductivity Analysis of Bi2Se3 Single Crystal
We report the high field (up to 14Tesla) magneto-conductivity analysis of
Bi2Se3 topological insulator grown via the self flux method. The detailed
experimental investigations including crystal growth as well as the electrical,
thermal and spectroscopic characterizations of the resultant Bi2Se3 single
crystal are already reported by some of us. The current letter deals with high
field magneto-conductivity analysis in terms of Hikami Larkin Nagaoka (HLN)
model, which revealed that the electronic conduction is dominated by both
surface states driven weak anti localization (WAL), as well the bulk WL (weak
localization) states. Further, by applying the HLN equation we have extracted
the fitting parameters i.e., phase coherence length and the pre-factor. The HLN
equation exhibited values of [pre factor close to -1.0, indicating both WAL and
WL contributions. On the other hand, the extracted phase coherence length is
seen to decrease from 11.125 nm to 5.576 nm as the temperature is increased
from 5K to 200K respectively. Summarily, the short letter discusses primarily
the temperature dependent magneto-conductivity analysis of pristine Bi2Se3
single crystal by the HLN model.Comment: Letter to Editor MS: 10 pages including 3 Fig
Crystal Growth and Characterization of Bulk Sb2Te3Topological Insulator
The Sb2Te3 crystals are grown using the conventional self flux method via
solid state reaction route, by melting constituent elements (Sb and Te) at high
temperature (850 C), followed by slow cooling (2 C per hour).The weak anti
localization (WAL) related low field (2 Tesla) magneto-conductance at low
temperatures (2.5 K and 20 K) has been analysed and discussed using the Hikami-
Larkin - Nagaoka (HLN) model. Summarily, the short letter reports an easy and
versatile method for crystal growth of bulk Sb2Te3 topological insulator (TI)
and its brief physical property characterization.Comment: 18 Pages Text + Figs: Accepted Mat. Res. Exp. (May 2018
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Retrospective analysis reveals significant association of hypoglycemia with tramadol and methadone in contrast to other opioids.
Tramadol is one of the most commonly used analgesics worldwide, classified as having a low abuse potential by U.S. Drug Enforcement Agency, and often recommended in pain management guidelines. Its pain-relieving mechanism of action is attributed to mild μ-opioid receptor agonism, serotonin and norepinephrine mediated nociception modulation, and N-methyl-D-aspartate receptor, NMDAR, antagonism. However, recent case reports and case-control studies have shown an association between tramadol use and hypoglycemia. The growing concern over increasing tramadol use and unexpected side effects warranted a further comparative and quantitative analysis of tramadol adverse reactions. In this study we analyzed over twelve million reports from United States Food and Drug Administration Adverse Event Reporting System and provided evidence of increased propensity for hypoglycemia in patients taking tramadol when compared to patients taking other opioids, serotonin-norepinephrine reuptake inhibitors, and drugs affecting NMDAR activity. Additionally, we identified that only methadone from the opioid cohort behaves similarly to tramadol and has an association with hypoglycemia
High Field (up to 140kOe) Angle Dependent Magneto Transport of Bi2Te3 Single Crystals
We report the angle dependent high field (up to 140kOe) magneto transport of
Bi2Te3 single crystals, a well-known topological insulator. The crystals were
grown from melt of constituent elements via solid state reaction route by
self-flux method. Details of crystal growth along with their brief
characterization up to 5 Tesla applied field was reported by some of us
recently [J. Magn. Mag. Mater. 428, 213 (2017)]. The angle dependence of the
magneto-resistance (MR) of Bi2Te3 follows the cos Theta function i.e., MR is
responsive, when the applied field is perpendicular (tilt angle Theta = o
and/or 180) to the transport current. The low field (10 kOe) MR showed the
signatures of weak anti localization (WAL) character with typical cusp near
origin at 5 K. Further, the MR is linear right up to highest applied field of
140 kOe. The large positive MR are observed up to high temperatures and are
above 250 and 150 percent at 140 kOe in perpendicular fields at 50 K and 100 K
respectively. Heat capacity CP(T) measurements revealed the value of Debye
temperature to be 135 K. ARPES (angle resolved photoemission spectroscopy) data
clearly showed that the bulk Bi2Te3 single crystal consists of a single Dirac
cone.Comment: 13 Pages text + Figs... Letter - Mat. Res. Ex
Diacritics improve comprehension of the Arabic script by providing access to the meanings of heterophonic homographs
The diacritical markers that represent most of the vowels in the Arabic orthography are generally omitted from written texts. Previous research revealed that the absence of diacritics reduces reading comprehension performance even by skilled readers of Arabic. One possible explanation is that many Arabic words become ambiguous when diacritics are missing. Words of this kind are known as heterophonic homographs and are associated with at least two different pronunciations and meanings when written without diacritics. The aim of the two experiments reported in this study was to investigate whether the presence of diacritics improves the comprehension of all written words, or whether the effects are confined to heterophonic homographs. In Experiment 1, adult readers of Arabic were asked to decide whether written words had a living meaning. The materials included heterophonic homographs that had one living and one non-living meaning. Results showed that diacritics significantly increased the accuracy of semantic decisions about ambiguous words but had no effect on the accuracy of decisions about unambiguous words. Consistent results were observed in Experiment 2 where the materials comprised sentences rather than single words. Overall, the findings suggest that diacritics improve the comprehension of heterophonic homographs by facilitating access to semantic representations that would otherwise be difficult to access from print
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Proton-pump inhibitor use is associated with a broad spectrum of neurological adverse events including impaired hearing, vision, and memory.
Proton-pump inhibitors, PPIs, are considered effective therapy for stomach acid suppression due to their irreversible inhibition of the hydrogen/potassium pump in the gastric parietal cells. They are widely prescribed and are considered safe for over-the-counter use. Recent studies have shown an association between PPI use and Alzheimer dementia, while others have disputed that connection. We analyzed over ten million United States Food and Drug Administration Adverse Event Reporting System reports, including over forty thousand reports containing PPIs, and provided evidence of increased propensity for memory impairment among PPI reports when compared to histamine-2 receptor antagonist control group. Furthermore, we found significant associations of PPI use with a wide range of neurological adverse reactions including, migraine, several peripheral neuropathies, and visual and auditory neurosensory abnormalities
The OIV 1407.3\AA /1401.1\AA\ emission-line ratio in a plasma
Line ratio of O IV 1407.3 \AA/1401.1 \AA\- is calculated using mostly our own
atomic and collisional data. Energy levels and oscillator strengths needed for
this calculation have been calculated using a Hartree-Fock relativistic (HFR)
approach. The electron collision strengths introduced in the statistic
equilibrium equations are fitted by polynomials for different energies.
Comparison has also been made with available theoretical results. The provided
line ratio has been obtained for a set of electron densities from
cm to cm and for a fixed temperature of 50 000 K.Comment: 6 pages, 1 figure, 2 tables. Accepted for publication in Advances in
Space Researc
The impact of mucosal infections on acquisition and progression of tuberculosis
More than one-third of the world\u27s population, or over 2 billion people, are infected with Mycobacterium tuberculosis, the causative pathogen of tuberculosis in humans. Why only 10% of those infected develop active disease while the remainder harbor latent infection remains one of the greatest scientific and public health mysteries. Bacterial persistence is characterized by a dynamic state of immunological tolerance between pathogen and host. The critical role of CD4(+) T cells in defense against intracellular pathogens became evident during epidemiological studies of HIV-1 infection, which showed a clear inverse relationship between CD4(+) T-cell count in peripheral blood and increased risk of infection with M. tuberculosis, pneumocystis and Toxoplasma gondii. There is also growing evidence of a common mucosal immune system, whereby immune cells activated at one mucosal site may disseminate to remote effector sites. In this commentary, we review emerging evidence from human studies that the outcome of M. tuberculosis infection is influenced by concurrent mucosal infections, using Helicobacter pylori and geohelminths as examples. Understanding how the complexity of microbial exposures influences host immunity may have important implications for vaccine development and therapeutic interventions
Electrical, Thermal and Spectroscopic Characterization of Bulk Bi2Se3 Topological Insulator
We report electrical (angular magneto-resistance, and Hall), thermal (heat
capacity) and spectroscopic (Raman, x-ray photo electron, angle resolved photo
electron) characterization of bulk Bi2Se3 topological insulator, which is being
is grown by self flux method through solid state reaction from high temperature
(950C) melt and slow cooling (2C/hour) of constituent elements. Bi2Se3
exhibited metallic behaviour down to 5K. Magneto transport measurements
revealed linear up to 400% and 30% MR at 5K under 14 Tesla field in
perpendicular and parallel field direction respectively. We noticed that the
magneto-resistance (MR) of Bi2Se3 is very sensitive to the angle of applied
field. MR is maximum when the field is normal to the sample surface, while it
is minimum when the field is parallel. Hall coefficient (RH) is seen nearly
invariant with negative carrier sign down to 5K albeit having near periodic
oscillations above 100K. Heat capacity (Cp) versus temperature plot is seen
without any phase transitions down to 5K and is well fitted (Cp = gammaT +
betaT3) at low temperature with calculated Debye temperature (ThetaD) value of
105.5K. Clear Raman peaks are seen at 72, 131 and 177 cm-1 corresponding to
A1g1, Eg2 and A1g2 respectively. Though, two distinct asymmetric characteristic
peak shapes are seen for Bi 4f7/2 and Bi 4f5/2, the Se 3d region is found to be
broad displaying the overlapping of spin - orbit components of the same.
Angle-resolved photoemission spectroscopy (ARPES) data of Bi2Se3 revealed
distinctly the bulk conduction bands (BCB), surface state (SS), Dirac point
(DP) and bulk valence bands (BVB) and 3D bulk conduction signatures are clearly
seen. Summarily, host of physical properties for as grown Bi2Se3 crystal are
reported here.Comment: 6 Pages Text + Figs; Comments Suggestions welcom
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