45 research outputs found
Proximity effect at superconducting Sn-Bi2Se3 interface
We have investigated the conductance spectra of Sn-Bi2Se3 interface junctions
down to 250 mK and in different magnetic fields. A number of conductance
anomalies were observed below the superconducting transition temperature of Sn,
including a small gap different from that of Sn, and a zero-bias conductance
peak growing up at lower temperatures. We discussed the possible origins of the
smaller gap and the zero-bias conductance peak. These phenomena support that a
proximity-effect-induced chiral superconducting phase is formed at the
interface between the superconducting Sn and the strong spin-orbit coupling
material Bi2Se3.Comment: 7 pages, 8 figure
Centrality Dependence of the High p_T Charged Hadron Suppression in Au+Au collisions at sqrt(s_NN) = 130 GeV
PHENIX has measured the centrality dependence of charged hadron p_T spectra
from central Au+Au collisions at sqrt(s_NN)=130 GeV. The truncated mean p_T
decreases with centrality for p_T > 2 GeV/c, indicating an apparent reduction
of the contribution from hard scattering to high p_T hadron production. For
central collisions the yield at high p_T is shown to be suppressed compared to
binary nucleon-nucleon collision scaling of p+p data. This suppression is
monotonically increasing with centrality, but most of the change occurs below
30% centrality, i.e. for collisions with less than about 140 participating
nucleons. The observed p_T and centrality dependence is consistent with the
particle production predicted by models including hard scattering and
subsequent energy loss of the scattered partons in the dense matter created in
the collisions.Comment: 7 pages text, LaTeX, 6 figures, 2 tables, 307 authors, resubmitted to
Phys. Lett. B. Revised to address referee concerns. Plain text data tables
for the points plotted in figures for this and previous PHENIX publications
are publicly available at
http://www.phenix.bnl.gov/phenix/WWW/run/phenix/papers.htm
Elliptic Flow of Identified Hadrons in Au+Au Collisions at sqrt(s_NN) = 200 GeV
The anisotropy parameter v_2, the second harmonic of the azimuthal particles
distribution, has been measured with the PHENIX detector in Au+Au collisions at
sqrt(s_NN) = 200 GeV for identified and inclusive charged particles at central
rapidities (|eta| < 0.35) with respect to the reaction plane defined at high
rapidities (|eta| = 3-4). The v_2 for all particles reaches a maximum at
mid-centrality, and increases with p_T up to 2 GeV/c and then saturates or
decreases slightly. Our results depart from hydrodynamically predicted behavior
above 2 GeV/c. A quark coalescence model is also investigated.Comment: 325 authors, 6 pages text, RevTeX, 3 figures, 0 tables. This version
accepted for publication in Phys. Rev. Lett. after minor changes in response
to referee suggestions. Plain text data tables for the points plotted in
figures for this and previous PHENIX publications are publicly available at
http://www.phenix.bnl.gov/papers.htm
Rare-earth elements as source indicators of Pan-African granites from Obudu Plateau, Southeastern Nigeria
Vitiligo puzzle: the pieces fall in place
A review. Over the years, the role of biochem., immunol., genetic, and other biol. aspects in the pathogenesis of vitiligo has been studied. So far, no convincing model describing the interplay of these contributing factors has been formulated. Based on existing research, we propose that vitiligo has a multi-factorial etiol., characterized by multiple steps, but always involving an increase of external or internal phenol/catechol concn., serving as a preferred surrogate substrate of tyrosinase, competing with its physiol. substrate tyrosine. The conversion of these substrates into reactive quinones is reinforced by a disturbed redox balance (increasing hydrogen peroxide). Such reactive quinones can be covalently bound to the catalytic center of tyrosinase (haptenation). This could give rise to a new antigen, carried by Langerhans cells to the regional lymph node, stimulating the proliferation of cytotoxic T cells. However, the activation of such cytotoxic cells is only a first step in skin melanocyte killing, which also depends on a shift in the balance between immune defense and tolerance, e.g. resulting from a decrease in properly functioning T-regulatory cells. With this new model, based on a synthesis of several of the existing theories, in mind, the external and internal factors involved in the etiopathogenesis of vitiligo are reviewed, against the background of reported clin. data, exptl. studies and existing and potential new therapies. A similar complex mechanism may also lead to some other autoimmune diseases
High- charged hadron suppression in Au-Au collisions at =200 GeV
The PHENIX experiment at the Relativistic Heavy Ion Collider has measured charged hadron yields at midrapidity over a wide range of transverse momenta (0.5<pT<10 GeV/c) in Au + Au collisions at √sNN=200 GeV. The data are compared to π0 measurements from the same experiment. For both charged hadrons and neutral pions, the yields per nucleon-nucleon collision are significantly suppressed in central compared to peripheral and nucleon-nucleon collisions. The suppression sets in gradually and increases with increasing centrality of the collisions. Above 4-5 GeV/c in pT, a constant and almost identical suppression of charged hadrons and π0's is observed. The pT spectra are compared to published spectra from Au+Au at √sNN=130 in terms of x T scaling. Central and peripheral π0 as well as peripheral charged spectra exhibit the same xT scaling as observed in p+p data
Suppression of hadrons with large transverse momentum in central Au+Au collisions at = 130GeV
Transverse momentum spectra for charged hadrons and for neutral pions in the range 1 GeV/