377 research outputs found
Entanglement can increase asymptotic rates of zero-error classical communication over classical channels
It is known that the number of different classical messages which can be
communicated with a single use of a classical channel with zero probability of
decoding error can sometimes be increased by using entanglement shared between
sender and receiver. It has been an open question to determine whether
entanglement can ever increase the zero-error communication rates achievable in
the limit of many channel uses. In this paper we show, by explicit examples,
that entanglement can indeed increase asymptotic zero-error capacity, even to
the extent that it is equal to the normal capacity of the channel.
Interestingly, our examples are based on the exceptional simple root systems E7
and E8.Comment: 14 pages, 2 figur
Prediction of infrared light emission from pi-conjugated polymers: a diagrammatic exciton basis valence bond theory
There is currently a great need for solid state lasers that emit in the
infrared, as this is the operating wavelength regime for applications in
telecommunications. Existing --conjugated polymers all emit in the visible
or ultraviolet, and whether or not --conjugated polymers that emit in the
infrared can be designed is an interesting challenge. On the one hand, the
excited state ordering in trans-polyacetylene, the --conjugated polymer
with relatively small optical gap, is not conducive to light emission because
of electron-electron interaction effects. On the other hand, excited state
ordering opposite to that in trans-polyacetylene is usually obtained by
chemical modification that increases the effective bond-alternation, which in
turn increases the optical gap. We develop a theory of electron correlation
effects in a model -conjugated polymer that is obtained by replacing the
hydrogen atoms of trans-polyacetylene with transverse conjugated groups, and
show that the effective on-site correlation in this system is smaller than the
bare correlation in the unsubstituted system. An optical gap in the infrared as
well as excited state ordering conducive to light emission is thereby predicted
upon similar structural modifications.Comment: 15 pages, 15 figures, 1 tabl
3D simulations of linearized scalar fields in Kerr spacetime
We investigate the behavior of a dynamical scalar field on a fixed Kerr
background in Kerr-Schild coordinates using a 3+1 dimensional spectral
evolution code, and we measure the power-law tail decay that occurs at late
times. We compare evolutions of initial data proportional to f(r)
Y_lm(theta,phi) where Y_lm is a spherical harmonic and (r,theta,phi) are
Kerr-Schild coordinates, to that of initial data proportional to f(r_BL)
Y_lm(theta_BL,phi), where (r_BL,theta_BL) are Boyer-Lindquist coordinates. We
find that although these two cases are initially almost identical, the
evolution can be quite different at intermediate times; however, at late times
the power-law decay rates are equal.Comment: 12 pages, 9 figures, revtex4. Major revision: added figures, added
subsection on convergence, clarified discussion. To appear in Phys Rev
Effect of Angiogenesis-Related Cytokines on Rotator Cuff Disease: The Search for Sensitive Biomarkers of Early Tendon Degeneration
Background Hallmarks of the pathogenesis of rotator cuff disease (RCD) include an abnormal immune response, angiogenesis, and altered variables of vascularity. Degenerative changes enhance production of pro-inflammatory, anti-inflammatory, and vascular angiogenesis-related cytokines (ARC) that play a pivotal role in the immune response to arthroscopic surgery and participate in the pathogenesis of RCD. The purpose of this study was to evaluate the ARC profile, ie, interleukin (IL): IL-1β, IL-6, IL-8, IL-10, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and angiogenin (ANG), in human peripheral blood serum and correlate this with early degenerative changes in patients with RCD. Methods Blood specimens were obtained from 200 patients with RCD and 200 patients seen in the orthopedic clinic for nonrotator cuff disorders. Angiogenesis imaging assays was performed using power Doppler ultrasound to evaluate variables of vascularity in the rotator cuff tendons. Expression of ARC was measured by commercial Bio-Plex Precision Pro Human Cytokine Assays. Results Baseline concentrations of IL-1β, IL-8, and VEGF was significantly higher in RCD patients than in controls. Significantly higher serum VEGF levels were found in 85% of patients with RCD, and correlated with advanced stage of disease (r = 0.75; P < 0.0005), average microvascular density (r = 0.68, P < 0.005), and visual analog score (r = 0.75, P < 0.0002) in RCD patients. ANG and IL-10 levels were significantly lower in RCD patients versus controls. IL-1β and ANG levels were significantly correlated with degenerative tendon grade in RCD patients. No difference in IL-6 and bFGF levels was observed between RCD patients and controls. Patients with degenerative changes had markedly lower ANG levels compared with controls. Power Doppler ultrasound showed high blood vessel density in patients with tendon rupture. Conclusion The pathogenesis of RCD is associated with an imbalance between pro-inflammatory, anti-inflammatory, and vascular ARC
Type IIB Colliding Plane Waves
Four-dimensional colliding plane wave (CPW) solutions have played an
important role in understanding the classical non-linearities of Einstein's
equations. In this note, we investigate CPW solutions in --dimensional
Einstein gravity with a -form flux. By using an isomorphism with the
four-dimensional problem, we construct exact solutions analogous to the
Szekeres vacuum solution in four dimensions. The higher-dimensional versions of
the Khan-Penrose and Bell-Szekeres CPW solutions are studied perturbatively in
the vicinity of the light-cone. We find that under small perturbations, a
curvature singularity is generically produced, leading to both space-like and
time-like singularities. For , our results pertain to the collision of two
ten-dimensional type IIB Blau - Figueroa o'Farrill - Hull - Papadopoulos plane
waves.Comment: 20+10 pages, 2 figures, uses JHEP3.cls; v2: refs [3,10,22] corrected,
remark added below (3.9) on inexistence of conformally flat CPW in our
ansatz, final version to appear in JHE
Fractional vortices on grain boundaries --- the case for broken time reversal symmetry in high temperature superconductors
We discuss the problem of broken time reversal symmetry near grain boundaries
in a d-wave superconductor based on a Ginzburg-Landau theory. It is shown that
such a state can lead to fractional vortices on the grain boundary. Both
analytical and numerical results show the structure of this type of state.Comment: 9 pages, RevTeX, 5 postscript figures include
Observing Supermassive Black Holes across cosmic time: from phenomenology to physics
In the last decade, a combination of high sensitivity, high spatial
resolution observations and of coordinated multi-wavelength surveys has
revolutionized our view of extra-galactic black hole (BH) astrophysics. We now
know that supermassive black holes reside in the nuclei of almost every galaxy,
grow over cosmological times by accreting matter, interact and merge with each
other, and in the process liberate enormous amounts of energy that influence
dramatically the evolution of the surrounding gas and stars, providing a
powerful self-regulatory mechanism for galaxy formation. The different
energetic phenomena associated to growing black holes and Active Galactic
Nuclei (AGN), their cosmological evolution and the observational techniques
used to unveil them, are the subject of this chapter. In particular, I will
focus my attention on the connection between the theory of high-energy
astrophysical processes giving rise to the observed emission in AGN, the
observable imprints they leave at different wavelengths, and the methods used
to uncover them in a statistically robust way. I will show how such a combined
effort of theorists and observers have led us to unveil most of the SMBH growth
over a large fraction of the age of the Universe, but that nagging
uncertainties remain, preventing us from fully understating the exact role of
black holes in the complex process of galaxy and large-scale structure
formation, assembly and evolution.Comment: 46 pages, 21 figures. This review article appears as a chapter in the
book: "Astrophysical Black Holes", Haardt, F., Gorini, V., Moschella, U and
Treves A. (Eds), 2015, Springer International Publishing AG, Cha
New hadrons as ultra-high energy cosmic rays
Ultra-high energy cosmic ray (UHECR) protons produced by uniformly
distributed astrophysical sources contradict the energy spectrum measured by
both the AGASA and HiRes experiments, assuming the small scale clustering of
UHECR observed by AGASA is caused by point-like sources. In that case, the
small number of sources leads to a sharp exponential cutoff at the energy
E<10^{20} eV in the UHECR spectrum. New hadrons with mass 1.5-3 GeV can solve
this cutoff problem. For the first time we discuss the production of such
hadrons in proton collisions with infrared/optical photons in astrophysical
sources. This production mechanism, in contrast to proton-proton collisions,
requires the acceleration of protons only to energies E<10^{21} eV. The diffuse
gamma-ray and neutrino fluxes in this model obey all existing experimental
limits. We predict large UHE neutrino fluxes well above the sensitivity of the
next generation of high-energy neutrino experiments. As an example we study
hadrons containing a light bottom squark. These models can be tested by
accelerator experiments, UHECR observatories and neutrino telescopes.Comment: 17 pages, revtex style; v2: shortened, as to appear in PR
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Review Essay : Industrial Organization and Socialist Development in China
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68697/2/10.1177_009770047900500204.pd
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