49 research outputs found
Critical Field Anisotropy and Muon Spin Relaxation Study of Superconducting Dirac-Semimetal CaSb
CaSb has been identified as a bulk superconductor and a topological
semimetal, which makes it a great platform for realizing topological
superconductivity. In this work, we investigate the superconducting upper and
lower critical field anisotropy using magnetic susceptibility, and study the
superconducting state using muon spin-relaxation. The temperature dependence of
transverse-field relaxation can be fitted with a single-gap model or two-gap
model, consistent with previous tunnel-diode oscillator measurements. We
highlight that the normal state of CaSb shows a large diamagnetic signal,
which is likely related to its Dirac semimetal nature. Zero-field relaxation
shows little temperature dependence when the muon-spin is parallel to the
-axis, while an increase in relaxation appears below 1~K when the muon-spin
is parallel to the -plane. This may be related to a second superconducting
phase appearing at low temperature below the bulk . However, we find no
discernible anomaly in around this temperature as
has been seen in other superconductors with secondary superconducting states
that appear at lower temperatures
Effect of sire, age at first calving, season and year of calving and parity on reproductive performance of Friesian cows under semiarid conditions in Egypt.
SUMMARY The objective of this paper was to study some factors affecting reproductive performance of a locally-born Friesian herd in Egypt. Data of 2096 reproductive records representing 482 Friesian cows daughters of 38 sires raised at the Dairy Unit of Milk and Meat Project of Faculty of Agriculture, Alexandria University, Egypt (located at the northern western part of the Nile Delta) between 1985-2002 were utilized to study the effects of sire of the cow, age at first calving (AFC), season and year of calving/birth and parity on period from parturition to first service (FSP), days open (DO), calving interval (CI), number of services per conception (NSC), AFC and breeding efficiency (BE). The least squares mixed model analysis by SAS (1999) indicated that the overall least squares means (± standard error) of FSP, DO, CI, NSC, AFC and BE were 88.4 ± 1.1, 130.7 ± 1.9, 403.1 ± 1.9 days, 2.1 ± 0.1 services, 30.7 ± 0.1 months and 90.1 ± 0.6 %, respectively. Sire had highly significant (P<0.01) effect on DO, CI, NSC and AFC, but had insignificant effect on FSP and BE. The influence of AFC on FSP was highly significant (P<0.01) and not significant on DO CI, NSC and BE. Cows had AFC more than 36 months had the longest FSP (92.6±4.5) and cows had AFC less than 29 months of age had 87.8±2.7 days FSP. Season of calving had significant effect on FSP (P<0.01), DO and CI (P<0.05), but had insignificant effect on NSC. Season of birth had no significant effect on both AFC and BE. Cows calving in autumn had the shortest CI (394.3±4.7 days) comparing with those calved in other seasons (ranged between 404.8±6.5 and 409.4±5.2 days). Cows calving in autumn also had the shortest DO (122.6±4.8 days). Year of calving/birth had significant (P<0.05 or P<0.01) effect on all traits studied. A decreasing efficiency in reproductive performance of cows was observed over time. The shortest FSP and DO were in the period 1988 to 1990 (64.3±5.3 and 98.1±8.9 days, respectively) and the longest were in the period 2000 to 2002 (107.5±5.2 and 188.1±8.8 days, respectively). Calving interval increased from 371 days in [1988][1989][1990] to 450 days †Corresponding autho
Adaptive hybrid technique for face recognition
One of the most important biometric features for personal identification is the face. In current paper, a new method of face verification upon on singular value decomposition (SVD) and standard deviation (SD) would be described. Due to many variations in real-life such as pose, illumination, or facial expression, there would be difficulty of face recognition. It should be mentioned that there are many approaches for face recognition, however, there is no one could be considered as the most suitable for many situations. One of the methods used is Singular value vector for an image detecting, but the drawback of this approach is the low rate of recognition, where one scale singular value vector is used for face acknowledgment. There an algorithm has been developed to expand the rate of the recognition. In this paper, an approach has been proposed to associate two feature sets obtained from SVD and SD method. It has noticed a good recognition rate could be obtained from the experimental results, where approximately more that 97.5% recognition rate has obtained on the ORL data base. The results from current proposed method have matched with some techniques and it has shown that this method is better than the existing approaches. An extensive experiment has demonstrated not only better performance, but it offers a great likely to achieve equivalent performance to other categories of state-of-the-art methods
Signature of an Ultrafast Photo-Induced Lifshitz Transition in the Nodal-Line Semimetal ZrSiTe
Here we report an ultrafast optical spectroscopic study of the nodal-line
semimetal ZrSiTe. Our measurements reveal that, converse to other compounds of
the family, the sudden injection of electronic excitations results in a
strongly coherent response of an phonon mode which dynamically
modifies the distance between Zr and Te atoms and Si layers. "Frozen phonon"
DFT calculations, in which band structures are calculated as a function of
nuclear position along the phonon mode coordinate, show that large
displacements along this mode alter the material's electronic structure
significantly, forcing bands to approach and even cross the Fermi energy. The
incoherent part of the time domain response reveals that a delayed electronic
response at low fluence discontinuously evolves into an instantaneous one for
excitation densities larger than cm. This sudden
change of the dissipative channels for electronic excitations is indicative of
an ultrafast Lifshitz transition which we tentatively associate to a change in
topology of the Fermi surface driven by a symmetry preserving phonon
mode
Discovery of Superconductivity and Electron-Phonon Drag in the Non-Centrosymmetric Semimetal LaRhGe
We present a comprehensive study of the non-centrosymmetric semimetal
LaRhGe. Our transport measurements reveal evidence for electron-hole
compensation at low temperatures, resulting in a large magnetoresistance of
3000% at 1.8 K and 14 T. The carrier concentration is on the order of
, higher than typical semimetals. We predict theoretically
the existence of Weyl nodal lines that are protected
by the tetragonal space group. We discover superconductivity for the first time
in this compound with a of 0.39(1) K and of
2.1(1) mT, with evidence from specific heat and transverse-field muon spin
relaxation (). LaRhGe is a weakly-coupled type-I
superconductor, and we find no evidence for time-reversal symmetry breaking in
our zero-field . We study the electrical transport in the normal
state and find an unusual dependence at low temperature while
Seebeck coefficient and thermal conductivity measurements reveal a peak in the
same temperature range. We conclude that the transport properties of LaRhGe
in its normal state are strongly influenced by electron-phonon interactions.
Furthermore, we examine the temperature dependent Raman spectra of LaRhGe
and find that the lifetime of the lowest energy phonon is dominated by
phonon-electron scattering instead of anharmonic decay
Superconductivity in (Ba,K)SbO3
Funding: This research was carried out in part due to funding from the Max Planck-UBC-UTokyo Centre for Quantum Materials. Part of the research described in this paper was performed at the Canadian Light Source, a national research facility of the University of Saskatchewan, which is supported by the Canada Foundation for Innovation, the Natural Sciences and Engineering Research Council, the National Research Council, the Canadian Institutes of Health Research, the Government of Saskatchewan and the University of Saskatchewan. We thank the Science and Technology Facilities Council ISIS facility for the provision of beamtime.(Ba,K)BiO3 constitute an interesting class of superconductors, where the remarkably high superconducting transition temperature Tc of 30 K arises in proximity to charge density wave order. However, the precise mechanism behind these phases remains unclear. Here, enabled by high-pressure synthesis, we report superconductivity in (Ba,K)SbO3 with a positive oxygen–metal charge transfer energy in contrast to (Ba,K)BiO3. The parent compound BaSbO3−δ shows a larger charge density wave gap compared to BaBiO3. As the charge density wave order is suppressed via potassium substitution up to 65%, superconductivity emerges, rising up to Tc = 15 K. This value is lower than the maximum Tc of (Ba,K)BiO3, but higher by more than a factor of two at comparable potassium concentrations. The discovery of an enhanced charge density wave gap and superconductivity in (Ba,K)SbO3 indicates that strong oxygen–metal covalency may be more essential than the sign of the charge transfer energy in the main-group perovskite superconductors.Publisher PDFPeer reviewe
Coronary Artery Bypass Grafting (CABG) versus Percutaneous Coronary Intervention (PCI) in treatment of left main coronary artery disease
BackgroundCoronary artery bypass graft surgery (CABG) has been widely used for left main coronary artery disease (LMCAD). Percutaneous coronary intervention (PCI) has become an option for this condition.AimsTo summarize the current evidence that compare between CABG vs. PCI in regards to ‎cardiac death, stroke, and myocardial infarction.‎Methods We searched randomized trials of treatment of LMCAD with PubMed, Google Scholar, and EBSCO.Results Five randomized studies were retrieved, which compared the efficacy between CABG vs. PCI in treatment of LMCAD.ConclusionPCI may be reasonable management of patients with LM stenosis involving distal bifurcation or with coexisting multivessel disease