5,326 research outputs found
Chromospheric impact of an exploding solar granule
Observations of multi-wavelength and therefore height-dependent information
following events throughout the solar atmosphere and unambiguously assigning a
relation between these rapidly evolving layers are rare and difficult to
obtain. Yet, they are crucial for our understanding of the physical processes
that couple the different regimes in the solar atmosphere. We characterize the
exploding granule event with simultaneous observations of Hinode
spectroplarimetric data in the solar photosphere and Hinode broadband CaIIH
images combined with Interface Region Imaging Spectrograph (IRIS) slit spectra.
We follow the evolution of an exploding granule and its connectivity throughout
the atmosphere and analyze the dynamics of a magnetic element that has been
affected by the abnormal granule. In addition to magnetic flux maps we use a
local correlation tracking method to infer the horizontal velocity flows in the
photosphere and apply a wavelet analysis on several IRIS chromospheric emission
features such as MgIIk2v and MgIIk3 to detect oscillatory phenomena indicating
wave propagation. During the vigorous expansion of the abnormal granule we
detect radially outward horizontal flows, causing, together with the horizontal
flows from the surrounding granules, the magnetic elements in the bordering
intergranular lanes to be squeezed and elongated. In reaction to the squeezing,
we detect a chromospheric intensity and velocity oscillation pulse which we
identify as an upward traveling hot shock front propagating clearly through the
IRIS spectral line diagnostics of MgIIh&k. Conclusion: Exploding granules can
trigger upward-propagating shock fronts that dissipate in the chromosphere.Comment: 5 pages (3 figures)+1 page movie snapshots(2 figures), accepted in
A&A letters, movies can be found at http://www.science-media.org/216 and
http://www.science-media.org/21
Designing helical peptide inhibitors of protein–protein interactions
Short helical peptides combine characteristics of small molecules and large proteins and provide an exciting area of opportunity in protein design. A growing number of studies report novel helical peptide inhibitors of protein-protein interactions. New techniques have been developed for peptide design and for chemically stabilizing peptides in a helical conformation, which frequently improves protease resistance and cell permeability. We summarize advances in peptide crosslinking chemistry and give examples of peptide design studies targeting coiled-coil transcription factors, Bcl-2 family proteins, MDM2/MDMX, and HIV gp41, among other targets.National Institute of General Medical Sciences (U.S.) (Award GM067681)National Institute of General Medical Sciences (U.S.) (Award GM110048)National Institute of General Medical Sciences (U.S.) (Award GM084181
The effect of sleep health behavioral education on the depression of pregnant women with sleep disorders: A randomized control trial
Background: About 79 of the pregnant women experience sleep disorders and 70 of pregnant women experience some symptoms of the depression. Physiologic, hormonal, and physical changes of pregnancy can predispose mothers to depression these disorders before, during, and after childbirth and might be aggravated by neglecting health behavior. Health behavior education might be useful for the management of depression in pregnant women. Objectives: This study aimed to evaluate the effect of sleep health behavioral education on the improvement of depression in pregnant women with sleep disorders. Patients and Methods: This study was a randomized clinical trial, performed on 96 pregnant women with sleep disorder diagnosed according to the Pittsburgh Sleep Quality Index. Tools for data collection included demographic questionnaire and Beck's Depression Inventory (BDI). Easy and accessible sampling was done. Participants were randomly (simple) allocated to intervention and control groups. In intervention group, sleep health behavior education was presented during a four-hour session held in weeks 22, 23, 24, and 25; then the patients were followed up to fill out the BDIQ in follow-up session at weeks 29 and 33 of pregnancy. The control group received no intervention and only received routine prenatal care. The results were assessed by Chi-square tests, independent-samples t-test, and Fischer�s exact-test by SPSS 16. Results: A statistically significant change was reported in the severity of depression in pregnant women with sleep disorders in the intervention group in comparison to the control group at weeks 29 (P < 0.000) and 33 (P < 0.00). Conclusions: Sleep health behavioral education improves depression in pregnant women who are experiencing insomnia. Findings from this study add support to the reported effectiveness of sleep health behavioral education in the prenatal care and clinical management of insomnia in pregnancy. © 2015, Iranian Red Crescent Medical Journal
A novel hydrogen peroxide biosensor based on modified electrode with hemoglobin and zinc oxide nanoparticles
In this study, direct electron transfer between immobilized hemoglobin (Hb) and zinc oxide nanoparticles modified carbon paste electrode was studied. Direct electrochemical response of Hb on the modified electrode can be achieved and a couple of well-defined and nearly reversible cyclic voltammetric peaks of Hb can be observed in a phosphate solution. The Hb immobilized on the Modified electrode with Zno Nps displayed a pair of redox peaks in 0.1 M pH 7.0 PBS with a formal potential of + (292 ± 2) mV (vs. SCE). Hb adsorbed on the modified electrode surface shows a good activity for the reduction of hydrogen peroxide (H2O2). The reduction peak currents were proportional linearly to the concentration of hydrogen peroxide. The Hb/ Zno Nps/ CPE had good repeatability and stability for the determination of H2O2
Gradient expansion, curvature perturbations and magnetized plasmas
The properties of magnetized plasmas are always investigated under the
hypothesis that the relativistic inhomogeneities stemming from the fluid
sources and from the geometry itself are sufficiently small to allow for a
perturbative description prior to photon decoupling. The latter assumption is
hereby relaxed and pre-decoupling plasmas are described within a suitable
expansion where the inhomogeneities are treated to a given order in the spatial
gradients. It is argued that the (general relativistic) gradient expansion
shares the same features of the drift approximation, customarily employed in
the description of cold plasmas, so that the two schemes are physically
complementary in the large-scale limit and for the low-frequency branch of the
spectrum of plasma modes. The two-fluid description, as well as the
magnetohydrodynamical reduction, are derived and studied in the presence of the
spatial gradients of the geometry. Various solutions of the coupled system of
evolution equations in the anti-Newtonian regime and in the quasi-isotropic
approximation are presented. The relation of this analysis to the so-called
separate Universe paradigm is outlined. The evolution of the magnetized
curvature perturbations in the nonlinear regime is addressed for the magnetized
adiabatic mode in the plasma frame.Comment: 40 pages, no figure
Rotating Lifshitz-like black holes in F(R) gravity
Regarding a particular class of pure gravity in three dimensions, we
obtain an analytical rotating Lifshitz-like black hole solution. We first
investigate some geometrical properties of the obtained solution that reduces
to a charged rotating BTZ black hole in a special limit. Then, we study the
optical features of such a black hole like the photon orbit and the energy
emission rate and discuss how electric charge, angular momentum, and exponents
affect them. In order to have an acceptable optical behavior, we should apply
some constraints on the exponents. We continue our investigation with the study
of the thermodynamic behavior of the solutions in the extended phase space and
examine the validity of the first law of thermodynamics besides local thermal
stability through using of heat capacity. Evaluating the existence of van der
Waals-like phase transition, we obtain critical quantities and show how they
change under the variation of black hole parameters. Finally, we construct a
holographic heat engine of such a black hole and obtain its efficiency in a
cycle. By comparing the obtained efficiency with the Carnot one, we examine the
second law of thermodynamics.Comment: 24 pages with 13 captioned figure
Generation of circular polarization of the CMB
According to the standard cosmology, near the last scattering surface, the
photons scattered via Compton scattering are just linearly polarized and then
the primordial circular polarization of the CMB photons is zero. In this work
we show that CMB polarization acquires a small degree of circular polarization
when a background magnetic field is considered or the quantum electrodynamic
sector of standard model is extended by Lorentz-noninvariant operators as well
as noncommutativity. The existence of circular polarization for the CMB
radiation may be verified during future observation programs and it represents
a possible new channel for investigating new physics effects.Comment: 28 pages, v3, Phys. Rev. D 81, 084035 (2010
Boundary Super-Deformations, Boundary States, and Tachyon Condensation
The open string tachyon and U(1) gauge field as longitudinal fluctuations and
the velocity as transverse fluctuation of an arbitrary dimensional D-brane are
considered as boundary deformations of a closed superstring free action. The
path integral approach will be applied to calculate the corresponding
generalized boundary states using supersymmetrized boundary actions. Obtaining
the disk partition functions from the boundary states and studying the effect
of tachyon condensation on both of them in the NSNS and RR sectors, leads to
results that differ from the established ones.Comment: 18 pages, no figur
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