6,842 research outputs found
STM imaging of electronic waves on the surface of BiTe: topologically protected surface states and hexagonal warping effects
Scanning tunneling spectroscopy studies on high-quality BiTe crystals
exhibit perfect correspondence to ARPES data, hence enabling identification of
different regimes measured in the local density of states (LDOS). Oscillations
of LDOS near a step are analyzed. Within the main part of the surface band
oscillations are strongly damped, supporting the hypothesis of topological
protection. At higher energies, as the surface band becomes concave,
oscillations appear which disperse with a particular wave-vector that may
result from an unconventional hexagonal warping term.Comment: 4 pages, 4 figures. Revised manuscript with improved analysis and
figure
Two-dimensional conformal field theory and the butterfly effect
We study chaotic dynamics in two-dimensional conformal field theory through
out-of-time order thermal correlators of the form .
We reproduce bulk calculations similar to those of [1], by studying the large
Virasoro identity block. The contribution of this block to the above
correlation function begins to decrease exponentially after a delay of , where is the scrambling
time , and are the energy scales of the
operators.Comment: v1: 14 pages plus appendices, 2 figures. v2: references updated and
minor changes to the text. v3: minor error corrected in Appendix B, but the
conclusion is unchange
The kinematics and morphology of NGC 520: One, two, or three galaxies
The peculiar galaxy NGC 520 (Arp 157) is often interpreted as an interacting pair of galaxies. The identification of the two bulges and overall morphology of the two galaxies has long been a puzzle which the authors attempt to solve here. New longslit optical spectroscopy and near-infrared images of NGC 520 are presented. These data suggest that the northwest peak is the bulge of one of two galaxies in the system. The other larger bulge is clearly evident in the K band image in the middle of the dust lane. The stellar radial velocity profile in the central 10 seconds of the larger bulge is consistent with counterrotation seen in the molecular gas component. This kinematic subsystem could be the remains of a merged gas-rich irregular
Localized shocks
We study products of precursors of spatially local operators,
, where .
Using chaotic spin-chain numerics and gauge/gravity duality, we show that a
single precursor fills a spatial region that grows linearly in . In a
lattice system, products of such operators can be represented using tensor
networks. In gauge/gravity duality, they are related to Einstein-Rosen bridges
supported by localized shock waves. We find a geometrical correspondence
between these two descriptions, generalizing earlier work in the spatially
homogeneous case.Comment: 23 pages plus appendices, 12 figures. v2: minor error in Appendix B
corrected. v3: figure added to the introduction comparing the butterfly
effect cone with the standard light con
EVOLUTION OF IR-SELECTED GALAXIES IN Z~0.4 CLUSTERS
Wide-field optical and near--IR () imaging is presented for two rich
galaxy clusters: Abell~370 at and Abell~851 (Cl0939+47) at .
Galaxy catalogs selected from the near--IR images are 90\% complete to
approximately 1.5 mag below resulting in samples with 100
probable member galaxies per cluster in the central 2 Mpc. Comparison
with WFPC images yields subsamples of 70 galaxies in each cluster
with morphological types. Analysis of the complete samples and the
subsamples shows that the E/S0s are bluer than those in the Bower
et al.\ (1992) Coma sample in the optical color by ~mag for Abell~370
and by ~mag for Abell~851. If real, the bluing of the E/S0 populations at
moderate redshift is consistent with that calculated from the Bruzual and
Charlot (1993) models of passive elliptical galaxy evolution. In both clusters
the intrinsic scatter of the known E/S0s about their optical color--mag
relation is small ( mag) and not significantly different from that
of Coma E/S0s as given by Bower et al.\ (1992), indicating that the galaxies
within each cluster formed at the same time at an early epoch.Comment: uuencoded gzipped tar file containing latex files of manuscript (42
pages) plus tables (9 pages); figures available by anonymous ftp at
ftp://ipac.caltech.edu//pub/pickup/sed ; accepted for publication in the Ap
Origin of charge density at LaAlO3-on-SrTiO3 hetero-interfaces; possibility of intrinsic doping
As discovered by Ohtomo et al., a large sheet charge density with high
mobility exists at the interface between SrTiO3 and LaAlO3. Based on transport,
spectroscopic and oxygen-annealing experiments, we conclude that extrinsic
defects in the form of oxygen vacancies introduced by the pulsed laser
deposition process used by all researchers to date to make these samples is the
source of the large carrier densities. Annealing experiments show a limiting
carrier density. We also present a model that explains the high mobility based
on carrier redistribution due to an increased dielectric constant.Comment: 14 pages, 3 figures, 1 table; accepted for publication in Phys. Rev.
Lett
Bobwhite Quail Population Dynamics: Relationships of Weather, Nesting, Production Patterns, Fall Population Characteristics, and Harvest in Missouri Quail
For 25 years Missouri has investigated bobwhite quail (Colinus virginianus) behavior, production, and population response to 4 major types of weather. Ten population parameters are examined annually to compare effects of Normal, Wet-Deluge, Snow-Cold and Drought weather years on quail populations, Different types of weather are related to varying annual quail abundance by affecting productivity and survival and influencing relative levels of annual harvest and hunter interest. Normal and Wet-Deluge years yield favorable fall quail populations and satisfactory hunting. Years having winters of severe snow and cold have high breeder losses, low production, and reduced hunting success. In years having high temperature and drought in spring and summer, quail reproduction is inhibited, resulting in high losses of eggs and young,greatly reduced fall bird crops, and below-par hunting for many hunters. Recovery from weather-caused population lows usually occurs within 2 or 3 years after favorable weather conditions return. Reliable techniques for sampling have been developed to yield indices of annual production and hunting success. Production curves show the value of data on the distribution of peaks in hatching for understanding annual production and fall population levels of quail in Missouri. Such data form the basis for setting annual hunting regulations of bobwhite harvest
The K-selected Butcher-Oemler Effect
[abridged] We investigate the Butcher-Oemler effect in a sample of K-selected
galaxies in 33 clusters at 0.15 < z < 0.92. We attempt to duplicate the
original Butcher-Oemler analysis as closely as possible given the
characteristics of our data. We find that the infrared selected blue fractions
are lower than those measured in the optical and that the trend with redshift
is much weaker. Comparison with optical data in clusters in common with Butcher
& Oemler (1984) shows that infrared selection is the primary difference between
our study and optically selected samples. We suggest that the Butcher-Oemler
effect is in large part due to a population of star-forming low mass galaxies
which will evolve into dwarf galaxies. These early results point to the need
for larger and deeper infrared samples of cluster galaxies to address this
issueComment: 37 pages, 19 figures, ApJ accepted (vol 598 n1
Verification of Germplasm Source and Status by Seed Certifying Agencies as Native Plants Are Collected and Cultivated
Development of a Bill of Materials from the PDXI Data Models
The research on the development of a bill of materials has resulted in the construction of a portion of the working data model, as designed in theory by the Process Data Exchange Institute (PDXI). The theoretical object model can be found in The PDXI Data Models [1]. It was necessary to develop this working data model in order to be able to produce the bill of materials. The bill of materials was created with the help of the software package Paradox for Windows (version 4.0)
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