1,181 research outputs found
On the harmonic measure of stable processes
Using three hypergeometric identities, we evaluate the harmonic measure of a
finite interval and of its complementary for a strictly stable real L{\'e}vy
process. This gives a simple and unified proof of several results in the
literature, old and recent. We also provide a full description of the
corresponding Green functions. As a by-product, we compute the hitting
probabilities of points and describe the non-negative harmonic functions for
the stable process killed outside a finite interval
Insulin-like growth factor-1 receptor inhibitor, AMG-479, in cetuximab-refractory head and neck squamous cell carcinoma
Background Recurrent head and neck squamous cell carcinoma (HNSCC) remains a difficult cancer to treat. Here, we describe a patient with HNSCC who had complete response to methotrexate (MTX) after progressing on multiple cytotoxic agents, cetuximab, and AMG-479 (monoclonal antibody against insulin-like growth factor-1 receptor [IGF-1R]). Methods The clinical information was collected by a retrospective medical record review under an Institutional Review Board-approved protocol. From 4 tumors and 2 normal mucosal epithelia, global gene expression, and IGF-1R and dihydrofolate reductase (DHFR) protein levels were determined. Results Effective target inhibition in the tumor was confirmed by the decreased protein levels of total and phospho-IGF-1R after treatment with AMG-479. Decreased level of DHFR and conversion of a gene expression profile associated with cetuximab-resistance to cetuximab-sensitivity were also observed. Conclusion This suggests that the combination of AMG-479 and MTX or cetuximab may be a promising therapeutic approach in refractory HNSCC
On Connected Diagrams and Cumulants of Erdos-Renyi Matrix Models
Regarding the adjacency matrices of n-vertex graphs and related graph
Laplacian, we introduce two families of discrete matrix models constructed both
with the help of the Erdos-Renyi ensemble of random graphs. Corresponding
matrix sums represent the characteristic functions of the average number of
walks and closed walks over the random graph. These sums can be considered as
discrete analogs of the matrix integrals of random matrix theory.
We study the diagram structure of the cumulant expansions of logarithms of
these matrix sums and analyze the limiting expressions in the cases of constant
and vanishing edge probabilities as n tends to infinity.Comment: 34 pages, 8 figure
Chiral Symmetry and Diffractive Neutral Pion Photo- and Electroproduction
We show that diffractive production of a single neutral pion in
photon-induced reactions at high energy is dynamically suppressed due to the
approximate chiral symmetry of QCD. These reactions have been proposed as a
test of the odderon exchange mechanism. We show that the odderon contribution
to the amplitude for such reactions vanishes exactly in the chiral limit. This
result is obtained in a nonperturbative framework and by using PCAC relations
between the amplitudes for neutral pion and axial vector current production.Comment: 22 pages, 7 figure
Impact of perioperative infarcts after cardiac surgery
Background and Purpose: Brain injury after cardiac surgery is a serious concern for patients and their families. The purpose of this study was to use 3-T fluid attenuated inversion recovery MRI to characterize new and preexisting cerebral ischemic lesions in patients undergoing cardiac surgery and to test whether the accumulation of new ischemic lesions adversely affects cognition.
Methods: Digital comparison of before and after fluid attenuated inversion recovery MRI images was performed for 77 cardiac surgery patients. The burden of preexisting versus new ischemic lesions was quantified and compared with the results of baseline and postoperative neuropsychological testing.
Results: After surgery, new lesions were identified in 31% of patients, averaging 0.5 lesions per patient (67 mm3 [0.004%] of brain tissue). Patients with preexisting lesions were 10× more likely to receive new lesions after surgery than patients without preexisting lesions. Preexisting ischemic lesions were observed in 64% of patients, averaging 19.4 lesions (1542 mm3 [0.1%] of brain tissue). New lesions in the left hemisphere were significantly smaller and more numerous (29 lesions; median volume, 44 mm3; volume range, 5–404 mm3) than those on the right (10 lesions; median volume, 128 mm3; volume range, 13–1383 mm3), which is consistent with a cardioembolic source of particulate emboli. Overall, the incidence of postoperative cognitive decline was 46% and was independent of whether new lesions were present.
Conclusions: New lesions after cardiac surgery added a small (≈4%) contribution to the burden of preexisting cerebrovascular disease and did not seem to affect cognitive function
Neutrino Masses, Baryon Asymmetry, Dark Matter and the Moduli Problem : A Complete Framework
Recent developments in string theory have led to "realistic" string
compactifications which lead to moduli stabilization while generating a
hierarchy between the Electroweak and Planck scales at the same time. However,
this seems to suggest a rethink of our standard notions of cosmological
evolution after the end of inflation and before the beginning of BBN. We argue
that within classes of realistic string compactifications, there generically
exists a light modulus with a mass comparable to that of the gravitino which
generates a large late-time entropy when it decays. Therefore, all known
mechanisms of generating the baryon asymmetry of the Universe in the literature
have to take this fact into account. In this work, we find that it is still
possible to naturally generate the observed baryon asymmetry of the Universe as
well as light left-handed neutrino masses from a period of Affleck-Dine(AD)
leptogenesis shortly after the end of inflation, in classes of realistic string
constructions with a minimal extension of the MSSM below the unification scale
(consisting only of right-handed neutrinos) and satisfying certain microscopic
criteria described in the text. The consequences are as follows. The lightest
left-handed neutrino is required to be virtually massless. The moduli
(gravitino) problem can be naturally solved in this framework both within
gravity and gauge mediation. The observed upper bound on the relic abundance
constrains the moduli-matter and moduli-gravitino couplings since the DM is
produced non-thermally within this framework. Finally, although not a definite
prediction, the framework naturally allows a light right-handed neutrino and
sneutrinos around the electroweak scale which could have important implications
for DM as well as the LHC.Comment: 41 pages, no figures, journal version adde
A simple model for the estimation of congenital malformation frequency in racially mixed populations
Effective interaction between helical bio-molecules
The effective interaction between two parallel strands of helical
bio-molecules, such as deoxyribose nucleic acids (DNA), is calculated using
computer simulations of the "primitive" model of electrolytes. In particular we
study a simple model for B-DNA incorporating explicitly its charge pattern as a
double-helix structure. The effective force and the effective torque exerted
onto the molecules depend on the central distance and on the relative
orientation. The contributions of nonlinear screening by monovalent counterions
to these forces and torques are analyzed and calculated for different salt
concentrations. As a result, we find that the sign of the force depends
sensitively on the relative orientation. For intermolecular distances smaller
than it can be both attractive and repulsive. Furthermore we report a
nonmonotonic behaviour of the effective force for increasing salt
concentration. Both features cannot be described within linear screening
theories. For large distances, on the other hand, the results agree with linear
screening theories provided the charge of the bio-molecules is suitably
renormalized.Comment: 18 pages, 18 figures included in text, 100 bibliog
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
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