2,232 research outputs found
A new class of drug in the diabetes toolbox
For nearly three decades, scientists have searched for an orally active small-molecule activator of glucokinase (GK) for the treatment of diabetes, because of its central role in glucose homeostasis in the pancreas and the liver1. The first report of a potential glucokinase activator (GKA) was published in 2003, and was followed by more than 150 patents and considerable attention by the pharmaceutical industry. Progress has been hampered by predictable adverse effects that were noted in early clinical studies; however, some have persevered, leveraging medicinal chemistry to engineer away adverse features. In this issue of Nature Medicine, Zhu et al. and Yang et al. report results of the SEED and DAWN studies, respectively — two phase 3 trials evaluating the GKA dorzagliatin in patients with type 2 diabete
Measurement of CH2O in low and atmospheric pressure flames by Laser Induced Fluorescence and Cavity RingDown absorption
We have investigated the spatial structure of formaldehyde usinglaser-induced fluorescence (LIF), LIF imaging, and cavity ringdownspectroscopy (CRDS) in two flames. The first is an atmospheric pressureBunsen flame, into which are inserted various metal to simulatedifferent types of heat removal inserts in appliance flames. Here LIFimaging is used. The second is a low pressure flat flame that can bemodeled with a one-dimensional code. All three techniques are used. Theresults in both cases show that CH2O appears prior to CH, inlower pressure regions of the flame
The QCD Phase Diagram at Nonzero Temperature, Baryon and Isospin Chemical Potentials in Random Matrix Theory
We introduce a random matrix model with the symmetries of QCD at finite
temperature and chemical potentials for baryon number and isospin. We analyze
the phase diagram of this model in the chemical potential plane for different
temperatures and quark masses. We find a rich phase structure with five
different phases separated by both first and second order lines. The phases are
characterized by the pion condensate and the chiral condensate for each of the
flavors. In agreement with lattice simulations, we find that in the phase with
zero pion condensate the critical temperature depends in the same way on the
baryon number chemical potential and on the isospin chemical potential. At
nonzero quark mass, we remarkably find that the critical end point at nonzero
temperature and baryon chemical potential is split in two by an arbitrarily
small isospin chemical potential. As a consequence, there are two crossovers
that separate the hadronic phase from the quark-gluon plasma phase at high
temperature. Detailed analytical results are obtained at zero temperature and
in the chiral limit.Comment: 13 pages, 5 figures, REVTeX
Modulation of Functional Activities of Chicken Heterophils by Recombinant Chicken IFN-γ
The objective of the present studies was to examine the in vitro effects of recombinant chicken interferon-γ (rChIFN-γ) on shape change, phagocytosis, and the oxidative/nonoxidative killing activities of day-old chicken heterophils. Heterophils (4 × 106/ml) were incubated with various concentrations of recombinant ChIFN-γ from both Escherichia coli and transfected Cos cells for 2 h at 39°C. The incubation of the neonatal heterophils with rChIFN-γ resulted in significantly greater numbers of cells with membrane shape change when compared with the mock-treated heterophils. Both Cos cell-derived and E. coli-derived ChIFN-γ significantly increased (p < 0.01) the phagocytosis of opsonized or nonopsonized Salmonella enteritidis by the neonatal heterophils in a concentration-dependent manner. Incubation with ChIFN-γ induced no direct stimulation of the respiratory burst by the chicken heterophils but did prime the heterophils for a significantly strengthened respiratory burst to subsequent stimulation with opsonized zymosan (OZ). Lastly, incubation of the heterophils with ChIFN-γ primed the cells for a significant increase in the release of β-D-glucuronidase following stimulation with OZ. These results show that neonatal avian heterophils can respond to cytokine modulation with enhanced functional competence, suggesting that ChIFN-γ can enhance the immune competence of the innate defenses of chickens during the first week of life
Modification of the pattern informatics method for forecasting large earthquake events using complex eigenvectors
Recent studies have shown that real-valued principal component analysis can
be applied to earthquake fault systems for forecasting and prediction. In
addition, theoretical analysis indicates that earthquake stresses may obey a
wave-like equation, having solutions with inverse frequencies for a given fault
similar to those that characterize the time intervals between the largest
events on the fault. It is therefore desirable to apply complex principal
component analysis to develop earthquake forecast algorithms. In this paper we
modify the Pattern Informatics method of earthquake forecasting to take
advantage of the wave-like properties of seismic stresses and utilize the
Hilbert transform to create complex eigenvectors out of measured time series.
We show that Pattern Informatics analyses using complex eigenvectors create
short-term forecast hot-spot maps that differ from hot-spot maps created using
only real-valued data and suggest methods of analyzing the differences and
calculating the information gain.Comment: 13 pages, 1 figure. Submitted to Tectonophysics on 30 August 200
A calculation of the QCD phase diagram at finite temperature, and baryon and isospin chemical potentials
We study the phases of a two-flavor Nambu-Jona-Lasinio model at finite
temperature , baryon and isospin chemical potentials:
, . This study
completes a previous analysis where only small isospin chemical potentials
were consideredComment: 21 pages, 13 figures included, two more refernces adde
Counting matrices over finite fields with support on skew Young diagrams and complements of Rothe diagrams
We consider the problem of finding the number of matrices over a finite field
with a certain rank and with support that avoids a subset of the entries. These
matrices are a q-analogue of permutations with restricted positions (i.e., rook
placements). For general sets of entries these numbers of matrices are not
polynomials in q (Stembridge 98); however, when the set of entries is a Young
diagram, the numbers, up to a power of q-1, are polynomials with nonnegative
coefficients (Haglund 98).
In this paper, we give a number of conditions under which these numbers are
polynomials in q, or even polynomials with nonnegative integer coefficients. We
extend Haglund's result to complements of skew Young diagrams, and we apply
this result to the case when the set of entries is the Rothe diagram of a
permutation. In particular, we give a necessary and sufficient condition on the
permutation for its Rothe diagram to be the complement of a skew Young diagram
up to rearrangement of rows and columns. We end by giving conjectures
connecting invertible matrices whose support avoids a Rothe diagram and
Poincar\'e polynomials of the strong Bruhat order.Comment: 24 pages, 9 figures, 1 tabl
Phase structures of strong coupling lattice QCD with finite baryon and isospin density
Quantum chromodynamics (QCD) at finite temperature (T), baryon chemical
potential (\muB) and isospin chemical potential (\muI) is studied in the strong
coupling limit on a lattice with staggered fermions. With the use of large
dimensional expansion and the mean field approximation, we derive an effective
action written in terms of the chiral condensate and pion condensate as a
function of T, \muB and \muI. The phase structure in the space of T and \muB is
elucidated, and simple analytical formulas for the critical line of the chiral
phase transition and the tricritical point are derived. The effects of a finite
quark mass (m) and finite \muI on the phase diagram are discussed. We also
investigate the phase structure in the space of T, \muI and m, and clarify the
correspondence between color SU(3) QCD with finite isospin density and color
SU(2) QCD with finite baryon density. Comparisons of our results with those
from recent Monte Carlo lattice simulations on finite density QCD are given.Comment: 18 pages, 6 figures, revtex4; some discussions are clarified, version
to appear in Phys. Rev.
Sign Rules for Anisotropic Quantum Spin Systems
We present new and exact ``sign rules'' for various spin-s anisotropic
spin-lattice models. It is shown that, after a simple transformation which
utilizes these sign rules, the ground-state wave function of the transformed
Hamiltonian is positive-definite. Using these results exact statements for
various expectation values of off-diagonal operators are presented, and
transitions in the behavior of these expectation values are observed at
particular values of the anisotropy. Furthermore, the effects of sign rules in
variational calculations and quantum Monte Carlo calculations are considered.
They are illustrated by a simple variational treatment of a one-dimensional
anisotropic spin model.Comment: 4 pages, 1 ps-figur
Solitary wave solution to the generalized nonlinear Schrodinger equation for dispersive permittivity and permeability
We present a solitary wave solution of the generalized nonlinear Schrodinger
equation for dispersive permittivity and permeability using a scaling
transformation and coupled amplitude-phase formulation. We have considered the
third-order dispersion effect (TOD) into our model and show that soliton shift
may be suppressed in a negative index material by a judicious choice of the TOD
and self-steepening parameter.Comment: 6 page
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