1,129 research outputs found
Band structure of SnTe studied by Photoemission Spectroscopy
We present an angle-resolved photoemission spectroscopy study of the
electronic structure of SnTe, and compare the experimental results to ab initio
band structure calculations as well as a simplified tight-binding model of the
p-bands. Our study reveals the conjectured complex Fermi surface structure near
the L-points showing topological changes in the bands from disconnected
pockets, to open tubes, and then to cuboids as the binding energy increases,
resolving lingering issues about the electronic structure. The chemical
potential at the crystal surface is found to be 0.5eV below the gap,
corresponding to a carrier density of p =1.14x10^{21} cm^{-3} or 7.2x10^{-2}
holes per unit cell. At a temperature below the cubic-rhombohedral structural
transition a small shift in spectral energy of the valance band is found, in
agreement with model predictions.Comment: 4 figure
Tin telluride: a weakly co-elastic metal
We report resonant ultrasound spectroscopy (RUS),
dilatometry/magnetostriction, magnetotransport, magnetization, specific heat,
and Sn M\"ossbauer spectroscopy measurements on SnTe and
SnCrTe. Hall measurements at K indicate that our
Bridgman-grown single crystals have a -type carrier concentration of cm and that our Cr-doped crystals have an -type
concentration of cm. Although our SnTe crystals are
diamagnetic over the temperature range , the Cr-doped crystals are room temperature ferromagnets with a Curie
temperature of 294 K. For each sample type, three-terminal capacitive
dilatometry measurements detect a subtle 0.5 micron distortion at K. Whereas our RUS measurements on SnTe show elastic hardening near the
structural transition, pointing to co-elastic behavior, similar measurements on
SnCrTe show a pronounced softening, pointing to
ferroelastic behavior. Effective Debye temperature, , values of SnTe
obtained from Sn M\"ossbauer studies show a hardening of phonons in the
range 60--115K ( = 162K) as compared with the 100--300K range
( = 150K). In addition, a precursor softening extending over
approximately 100 K anticipates this collapse at the critical temperature, and
quantitative analysis over three decades of its reduced modulus finds with , a value
indicating a three-dimensional softening of phonon branches at a temperature
K, considerably below . We suggest that the differences in
these two types of elastic behaviors lie in the absence of elastic domain wall
motion in the one case and their nucleation in the other
Particle dependence of elliptic flow in Au+Au collisions at 200 GeV
The elliptic flow parameter () for and
has been measured at mid-rapidity in Au + Au collisions at
GeV by the STAR collaboration. The values for both
and saturate at moderate , deviating
from the hydrodynamic behavior observed in the lower region. The
saturated values and the scales where the deviation begins are
particle dependent. The particle-type dependence of shows features
expected from the hadronization of a partonic ellipsoid by coalescence of
co-moving quarks. These results will be discussed in relation to the nuclear
modification factor () which has also been measured for and
by the STAR collaboration.Comment: 6 pages, 3 figures, Strange Quark Matter 2003 Conference (SQM 2003):
updated with 2 figures from original talk that did not appear in the journa
New results from the NA57 experiment
We report results from the experiment NA57 at CERN SPS on hyperon production
at midrapidity in Pb-Pb collisions at 158 GeV/ and 40 GeV/.
, and yields are compared with those from the STAR
experiment at the higher energy of the BNL RHIC. , , \
and preliminary transverse mass spectra are presented and interpreted
within the framework of a hydro-dynamical blast wave model.Comment: 8 pages, 3 figures, contribution to the proceedings of The XXXVIIIth
Rencontres de Moriond "QCD and High Energy Hadronic Interactions
Strange particle production in 158 and 40 GeV/ Pb-Pb and p-Be collisions
Results on strange particle production in Pb-Pb collisions at 158 and 40
GeV/ beam momentum from the NA57 experiment at CERN SPS are presented.
Particle yields and ratios are compared with those measured at RHIC.
Strangeness enhancements with respect to p-Be reactions at the same beam
momenta have been also measured: results about their dependence on centrality
and collision energy are reported and discussed.Comment: Contribution to the proceedings of the "Hot Quarks 2004" Conference,
July 18-24 2004, New Mexico, USA, submitted to Journal of Physics G 7 pages,
5 figure
Effective Rheology of Bubbles Moving in a Capillary Tube
We calculate the average volumetric flux versus pressure drop of bubbles
moving in a single capillary tube with varying diameter, finding a square-root
relation from mapping the flow equations onto that of a driven overdamped
pendulum. The calculation is based on a derivation of the equation of motion of
a bubble train from considering the capillary forces and the entropy production
associated with the viscous flow. We also calculate the configurational
probability of the positions of the bubbles.Comment: 4 pages, 1 figur
Equipping Health Professions Educators to Better Address Medical Misinformation
As part of a cooperative agreement with the US Centers for Disease Control and Prevention (Federal Award Identification Number [FAIN]: NU50CK000586), the Association of American Medical Colleges (AAMC) began a strategic initiative in 2022 both to increase confidence in COVID-19 vaccines and to address medical misinformation and mistrust through education in health professions contexts. Specifically, the AAMC solicited proposals for integrating competency-based, interprofessional strategies to mitigate health misinformation into new or existing curricula. Five Health Professions Education Curricular Innovations subgrantees received support from the AAMC in 2022 and reflected on the implementation of their ideas in a series of meetings over several months. Subgrantees included the Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Florida International University Herbert Wertheim College of Medicine, the Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, the Maine Medical Center/Tufts University School of Medicine, and the University of Chicago Pritzker School of Medicine. This paper comprises insights from each of the teams and overarching observations regarding the challenges and opportunities involved with leveraging health professions education to address medical misinformation and improve patient health
Isolation and characterization of three distinct forms of lipases from Candida rugosa produced in solid state fermentation
Insight into aquaculture's potential of marine annelid worms and ecological concerns: a review
Polychaetes are marine annelid worms that can contribute to aquaculture diversification. Its culture has been viable, and commercially attempted, but intensive
production has progressed only in few countries around the world. In the countries with no production, marine polychaetes are imported or harvested. A strong
and sustained research investment provided to a better understanding of the
nutritional requirements and reproduction of some species. Recent studies
showed new technical improvements, which can lead to an important progress in
productivity and give a new impetus to the polychaete production. Some marine
worm species were identified as good candidates for integrated multitrophic
aquaculture. The development of cost-effective aquaculture techniques for marine
annelid worms is essential to ensure a balance between commercial interests and
the preservation of ecosystems. The influence of polychaete aquaculture on the
environment and vice versa raise important concerns related to ecological security
and sustainability of this activity. This review focus on the main technical
improvements and advances that have been made in areas as diverse as: aquaculture potential of polychaetes, reared species, main species used worldwide, and
highlights biological and ecological concerns, important challenges and recommendations.This study was supported by the
FCT (Portuguese National Board of Scientific Research),
through the MARE (Marine and Environmental Sciences
Centre) (UID/MAR/04292/2013) strategic programme and
through strategic project PEst-OE/MAR/UI0199/2014,
granted to MARE. This study has also the financial support
of PROMAR Program through the project 31-03-05-FEP42: LIVE BAIT – Annelid polychaetes as live bait in Portugal: harvesting, import and rearing management.info:eu-repo/semantics/publishedVersio
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