121,981 research outputs found
Telomere length as a predictor of response to Pioglitazone in patients with unremitted depression: a preliminary study.
We studied peripheral leukocyte telomere length (LTL) as a predictor of antidepressant response to PPAR-γ agonist in patients with unremitted depression. In addition we examined correlation between LTL and the insulin resistance (IR) status in these subjects. Forty-two medically stable men and women ages 23-71 with non-remitted depression participated in double-blind placebo-controlled add-on of Pioglitazone to treatment-as-usual. Oral glucose tolerance tests were administered at baseline and at 12 weeks. Diagnostic evaluation of psychiatric disorders was performed at baseline and mood severity was followed weekly throughout the duration of the trial. At baseline, no differences in LTL were detected by depression severity, duration or chronicity. LTL was also not significantly different between insulin-resistant and insulin-sensitive subjects at baseline. Subjects with longer telomeres exhibited greater declines in depression severity in the active arm, but not in a placebo arm, P=0.005, r=-0.63, 95% confidence interval (95% CI)=(-0.84,-0.21). In addition, LTL predicted improvement in insulin sensitivity in the group overall and did not differ between intervention arms, P=0.036, r=-0.44, 95% CI=(-0.74,0.02) for the active arm, and P=0.026, r=-0.50, 95% CI=(-0.78,-0.03) for the placebo arm. LTL may emerge as a viable predictor of antidepressant response. An association between insulin sensitization and LTL regardless of the baseline IR status points to potential role of LTL as a non-specific moderator of metabolic improvement in these patients
Symplectic reduction and topology for applications in classical molecular dynamics
This paper aims to introduce readers with backgrounds in classical molecular dynamics to some ideas in geometric mechanics that may be useful. This is done through some simple but specific examples: (i) the separation of the rotational and internal energies in an arbitrarily floppy N-body system and (ii) the reduction of the phase space accompanying the change from the laboratory coordinate system to the center of mass coordinate system relevant to molecular collision dynamics. For the case of two-body molecular systems constrained to a plane, symplectic reduction is employed to demonstrate explicitly the separation of translational, rotational, and internal energies and the corresponding reductions of the phase space describing the dynamics for Hamiltonian systems with symmetry. Further, by examining the topology of the energy-momentum map, a unified treatment is presented of the reduction results for the description of (i) the classical dynamics of rotating and vibrating diatomic molecules, which correspond to bound trajectories and (ii) the classical dynamics of atom–atom collisions, which correspond to scattering trajectories. This provides a framework for the treatment of the dynamics of larger N-body systems, including the dynamics of larger rotating and vibrating polyatomic molecular systems and the dynamics of molecule–molecule collisions
Ruderman-Kittel-Kasuya-Yosida interactions on a bipartite lattice
Carrier-mediated exchange coupling, known as Ruderman-Kittel-Kasuya-Yosida
(RKKY) interaction, plays a fundamental role in itinerant ferromagnetism and
has great application potentials in spintronics. A recent theorem based on the
imaginary-time method shows that the oscillatory RKKY interaction becomes
commensurate on bipartite lattice and predicts that the effective exchange
coupling is always ferromagnetic for the same sublattice but antiferromagnetic
for opposite sublattices. We revisit this important problem by real- and
imaginary-time methods and find the theorem misses important contributions from
zero modes. To illustrate the importance of zero modes, we study the spin
susceptibility in graphene nanoribbons numerically. The effective exchange
coupling is largest on the edges but does not follow the predictions from the
theorem
Phase diagrams of the metallic zigzag carbon nanotube
We investigate a metallic zigzag carbon nanotube by means of a Hubbard model
which includes both on-site and nearest neighbour interactions. Assuming weak
interactions, a renormalization group analysis of the equivalent two-leg ladder
followed by bosonization and refermionization results in a Gross-Neveu model
with an enlarged symmetry relative to the original Hamiltonian. For the undoped
case the symmetry of the Gross-Neveu model is SO(8), but for the doped case the
particle-hole symmetry is broken and the symmetry reduces to SO(6). Four ground
state phases are found in the undoped carbon nanotube with repulsive
interactions, a d-wave Mott insulator, an s-wave Mott insulator, a p-density
wave and a charge density wave. The doped case has two ground state phases, a
d-wave superconductor and a phase where a p-density wave and a charge density
wave co-exist. We also explore the global phase diagram with a general
interaction profile and find several additional states, including a chiral
current phase where current flows around the nanotube along the zigzag bonds.Comment: 16 pages, 9 figure
Unusual Tunneling Characteristics of Double-quantum-well Heterostructures
We report tunneling phenomena in double InGaAs quantum-well
structures that are at odds with the conventional parallel-momentum-conserving
picture of tunneling between two-dimensional systems. We found that the
tunneling current was mostly determined by the correlation between the emitter
and the state in one well, and not by that between those in both wells. Clear
magnetic-field-dependent features were first observed before the main
resonance, corresponding to tunneling channels into the Landau levels of the
well near the emitter. These facts provide evidence of the violation of
in-plane momentum conservation in two-dimensional systems.Comment: Submitted to ICPS-27 conference proceeding as a contributed pape
Improvement of black nickel coatings
Selectively absorbing black nickel coatings are among the most optically efficient low cost coatings for use on flat plate solar collectors. However, a current Ni-Zn-S-O coating in use is quite susceptible to a humid environment, degrading badly in less than ten days at 38 C (100 F) at 95 percent relative humidity. Therefore, a black nickel formula was developed which can withstand such exposures with no loss of optical efficiency, solar absorption of 0.92 and an infrared emittance (at 100 C) of 1.00 were still present after 14 days of humidity exposure. This compares to a solar absorptance of only 0.72 for the previous formula after a similar time period. The electroplating bath and conditions were changed to obtain the more stable coating configuration. The effect of bath composition, temperature, pH, and plating current density and time on the coating composition, spectral optical properties and durability were investigated systematically
Toward the AdS/CFT gravity dual for High Energy Collisions: I.Falling into the AdS
In the context of the AdS/CFT correspondence we discuss the gravity dual of a
high energy collision in a strongly coupled SYM gauge theory. We
suggest a setting in which two colliding objects are made of non-dynamical
heavy quarks and antiquarks, which allows to treat the process in classical
string approximation. Collision ``debris'' consist of closed as well as open
strings. If the latter have ends on two outgoing charges, and thus are being
``stretched'' along the collision axes. We discuss motion in AdS of some simple
objects first -- massless and massive particles -- and then focus on open
strings. We study the latter in a considerable detail, concluding that they
rapidly become ``rectangular'' in proper time -spatial rapidity
coordinates with well separated fragmentation part and a near-free-falling
rapidity-independent central part. Assuming that in the collisions of ``walls''
of charges multiple stretching strings are created, we also consider the motion
of a 3d stretching membrane. We then argue that a complete solution can be
approximated by two different vacuum solutions of Einstein eqns, with matter
membrane separating them. We identify one of this solution with
Janik-Peschanski stretching black hole solution, and show that all objects
approach its (retreating) horizon in an universal manner.Comment: v2 was redone, with new material and different introduction. It now
includes introduction to the second paper of the series as well, in which we
calculate "holograms" of falling objects, namely their stress tensor on the
boundar
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