2,747 research outputs found
High pressure effect on structure, electronic structure and thermoelectric properties of MoS
We systematically study the effect of high pressure on the structure,
electronic structure and transport properties of 2H-MoS, based on
first-principles density functional calculations and the Boltzmann transport
theory. Our calculation shows a vanishing anisotropy in the rate of structural
change at around 25 GPa, in agreement with the experimental data. A conversion
from van der Waals(vdW) to covalent-like bonding is seen. Concurrently, a
transition from semiconductor to metal occurs at 25 GPa from band structure
calculation. Our transport calculations also find pressure-enhanced electrical
conductivities and significant values of the thermoelectric figure of merit
over a wide temperature range. Our study supplies a new route to improve the
thermoelectric performance of MoS and of other transition metal
dichalcogenides by applying hydrostatic pressure.Comment: 6 pages, 6 figures; published in JOURNAL OF APPLIED PHYSICS 113, xxxx
(2013
Successful Pregnancy after Treatment with Chinese Herbal Medicine in a 43-Year-Old Woman with Diminished Ovarian Reserve and Multiple Uterus Fibrosis: A Case Report.
OBJECTIVE: To highlight a natural approach to coexisting oligomenorrhea, subfertility, luteal phase insufficiency and multiple fibroids cohesively when in vitro fertilisation (IVF) has failed. CASE PRESENTATION: A 43-year-old woman with diminished ovarian reserve and multiple uterine fibroids had previously been advised to discontinue IVF treatment. According to Chinese Medicine diagnosis, herbal formulae were prescribed for improving age-related ovarian insufficiency as well as to control the growth of fibroids. After 4 months of treatment, the patient's menstrual cycle became regula r and plasma progesterone one week after ovulation increased from 10.9 nmol/L to 44.9 nmol/L. After 6 months, she achieved a natural conception, resulting in a live birth of a healthy infant at an estimated gestational age of 40 weeks. CONCLUSIONS: The successful treatment with Chinese Herbal Medicine for this case highlights a natural therapy to manage infertility due to ovarian insufficiency and multiple fibroids after unsuccessful IVF outcome
Long Term Potential Evapotranspiration and Evapotranspiration Data and Services at NASA GES DISC
Recently, the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) has released global land 3-hourly Potential Evapotranspiration and Supporting Forcing Data Version-1 (PET_PU_3H025.001), at 0.25x0.25 degree spatial resolution, spanning the 23 year period from 1984 to 2006. The Version-2 will be released in the near future, covering longer time period. This dataset was generated by Professor Justin Sheffield through NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) project. Potential evapotranspiration (PET) is a representation of the environmental demand for evapotranspiration (ET). ET and PET are important part of the global water cycle estimation, and are also critical to advance our understanding of the climate system. NASA GES DISC archives and distributes various global and regional ET datasets from several projects, for example, Land Data Assimilation System (LDAS), Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2), other MEaSUREs Projects, such as Land Surface Atmospheric Boundary Interaction Product by William Rossow; and SRB/GEWEX evapotranspiration (Penman-Monteith) by Eric F. Wood. In this presentation, we will overview all available PET and ET datasets and services at GES DISC. As examples, climatology and some seasonal characteristics of PET and selected ET will be shown. The data can be accessed from NASA GES DISC (https://disc.gsfc.nasa.gov/) by searching keyword "evapotranspiration"
A Review on Mechanics and Mechanical Properties of 2D Materials - Graphene and Beyond
Since the first successful synthesis of graphene just over a decade ago, a
variety of two-dimensional (2D) materials (e.g., transition
metal-dichalcogenides, hexagonal boron-nitride, etc.) have been discovered.
Among the many unique and attractive properties of 2D materials, mechanical
properties play important roles in manufacturing, integration and performance
for their potential applications. Mechanics is indispensable in the study of
mechanical properties, both experimentally and theoretically. The coupling
between the mechanical and other physical properties (thermal, electronic,
optical) is also of great interest in exploring novel applications, where
mechanics has to be combined with condensed matter physics to establish a
scalable theoretical framework. Moreover, mechanical interactions between 2D
materials and various substrate materials are essential for integrated device
applications of 2D materials, for which the mechanics of interfaces (adhesion
and friction) has to be developed for the 2D materials. Here we review recent
theoretical and experimental works related to mechanics and mechanical
properties of 2D materials. While graphene is the most studied 2D material to
date, we expect continual growth of interest in the mechanics of other 2D
materials beyond graphene
Detecting and Characterizing Small Dense Bipartite-like Subgraphs by the Bipartiteness Ratio Measure
We study the problem of finding and characterizing subgraphs with small
\textit{bipartiteness ratio}. We give a bicriteria approximation algorithm
\verb|SwpDB| such that if there exists a subset of volume at most and
bipartiteness ratio , then for any , it finds a set
of volume at most and bipartiteness ratio at most
. By combining a truncation operation, we give a local
algorithm \verb|LocDB|, which has asymptotically the same approximation
guarantee as the algorithm \verb|SwpDB| on both the volume and bipartiteness
ratio of the output set, and runs in time
, independent of the size of the
graph. Finally, we give a spectral characterization of the small dense
bipartite-like subgraphs by using the th \textit{largest} eigenvalue of the
Laplacian of the graph.Comment: 17 pages; ISAAC 201
An assessment on the incremental value of high-resolution magnetic resonance imaging to identify culprit plaques in atherosclerotic disease of the middle cerebral artery.
OBJECTIVE: Although certain morphological features depicted by high resolution, multi-contrast magnetic resonance imaging (hrMRI) have been shown to be different between culprit and non-culprit middle cerebral artery (MCA) atherosclerotic lesions, the incremental value of hrMRI to define culprit lesions over stenosis has not been assessed. METHODS: Patients suspected with MCA stenosis underwent hrMRI. Lumen and outer wall were segmented to calculate stenosis, plaque burden (PB), volume (PV), length (PL) and minimum luminal area (MLA). RESULTS: Data from 165 lesions (112 culprit and 53 non-culprit) in 139 individuals were included. Culprit lesions were larger and longer with a narrower lumen and increased PB compared with non-culprit lesions. More culprit lesions showed contrast enhancement. Both PB and MLA were better indicators than stenosis in differentiating lesion types (AUC were 0.649, 0.732 and 0.737 for stenosis, PB and MLA, respectively). Combinations of PB, MLA and stenosis could improve positive predictive value (PPV) and specificity significantly. An optimal combination of stenosis ≥ 50 %, PB ≥ 77 % and MLA ≤ 2.0 mm(2) produced a PPV = 85.7 %, negative predictive value = 54.1 %, sensitivity = 69.6 %, specificity = 75.5 %, and accuracy = 71.5 %. CONCLUSIONS: hrMRI plaque imaging provides incremental information to luminal stenosis in identifying culprit lesions. KEY POINTS: • High resolution MRI provides incremental information in defining culprit MCA atherosclerotic lesions. • Both plaque burden and minimum luminal area are better indicators than stenosis. • An optimal combination includes stenosis ≥ 50 %, PB ≥ 77 % and MLA ≤ 2.0 mm (2) .This research is supported by Shanghai Shenkang Porject SHDC12013110, Shanghai, China; British Heart Foundation (BHF) PG/11/74/29100; and the NIHR Cambridge Biomedical Research Centre, Cambridge, UK. Dr Peng is supported by China Scholarship Council (201306580006), Beijing, China.This is the final version of the article. It first appeared from Springer via http://dx.doi.org/10.1007/s00330-015-4008-
Large-scale on-chip integration of gate-voltage addressable hybrid superconductor-semiconductor quantum wells field effect nano-switch arrays
Stable, reproducible, scalable, addressable, and controllable hybrid
superconductor-semiconductor (S-Sm) junctions and switches are key circuit
elements and building blocks of gate-based quantum processors. The
electrostatic field effect produced by the split gate voltages facilitates the
realisation of nano-switches that can control the conductance or current in the
hybrid S-Sm circuits based on 2D semiconducting electron systems. Here, we
experimentally demonstrate a novel realisation of large-scale scalable, and
gate voltage controllable hybrid field effect quantum chips. Each chip contains
arrays of split gate field effect hybrid junctions, that work as conductance
switches, and are made from In0.75Ga0.25As quantum wells integrated with Nb
superconducting electronic circuits. Each hybrid junction in the chip can be
controlled and addressed through its corresponding source-drain and two global
split gate contact pads that allow switching between their (super)conducting
and insulating states. We fabricate a total of 18 quantum chips with 144 field
effect hybrid Nb- In0.75Ga0.25As 2DEG-Nb quantum wires and investigate the
electrical response, switching voltage (on/off) statistics, quantum yield, and
reproducibility of several devices at cryogenic temperatures. The proposed
integrated quantum device architecture allows control of individual junctions
in a large array on a chip useful for the development of emerging cryogenic
nanoelectronics circuits and systems for their potential applications in
fault-tolerant quantum technologies
PTPα regulates integrin-stimulated FAK autophosphorylation and cytoskeletal rearrangement in cell spreading and migration
We investigated the molecular and cellular actions of receptor protein tyrosine phosphatase (PTP) α in integrin signaling using immortalized fibroblasts derived from wild-type and PTPα-deficient mouse embryos. Defects in PTPα−/− migration in a wound healing assay were associated with altered cell shape and focal adhesion kinase (FAK) phosphorylation. The reduced haptotaxis to fibronectin (FN) of PTPα−/− cells was increased by expression of active (but not inactive) PTPα. Integrin-mediated formation of src–FAK and fyn–FAK complexes was reduced or abolished in PTPα−/− cells on FN, concomitant with markedly reduced phosphorylation of FAK at Tyr397. Reintroduction of active (but not inactive) PTPα restored FAK Tyr-397 phosphorylation. FN-induced cytoskeletal rearrangement was retarded in PTPα−/− cells, with delayed filamentous actin stress fiber assembly and focal adhesion formation. This mimicked the effects of treating wild-type fibroblasts with the src family protein tyrosine kinase (Src-PTK) inhibitor PP2. These results, together with the reduced src/fyn tyrosine kinase activity in PTPα−/− fibroblasts (Ponniah et al., 1999; Su et al., 1999), suggest that PTPα functions in integrin signaling and cell migration as an Src-PTK activator. Our paper establishes that PTPα is required for early integrin-proximal events, acting upstream of FAK to affect the timely and efficient phosphorylation of FAK Tyr-397
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