1,255 research outputs found
Application of Subset Simulation to Seismic Risk Analysis
This paper presents the application of a new reliability method called Subset Simulation to seismic risk analysis of a structure, where the exceedance of some performance quantity, such as the peak
interstory drift, above a specified threshold level is considered for the case of uncertain seismic excitation. This involves analyzing the well-known but difficult first-passage failure problem. Failure analysis
is also carried out using results from Subset Simulation which yields information about the probable
scenarios that may occur in case of failure. The results show that for given magnitude and epicentral distance (which are related to the ‘intensity’ of shaking), the probable mode of failure is due to a
‘resonance effect.’ On the other hand, when the magnitude and epicentral distance are considered to be
uncertain, the probable failure mode correspondsto the occurrence of ‘large-magnitude, small epicentral
distance’ earthquakes
Combinatorial search of superconductivity in Fe-B composition spreads
We have fabricated Fe-B thin film composition spreads in search of possible
superconducting phases following a theoretical prediction by Kolmogorov et
al.^1 Co-sputtering was used to deposit spreads covering a large compositional
region of the Fe-B binary phase diagram. A trace of superconducting phase was
found in the nanocrystalline part of the spread, where the film undergoes a
metal to insulator transition as a function of composition in a region with the
average composition of FeB_2. The resistance drop occurs at 4K, and a
diamagnetic signal has also been detected at the same temperature. The
superconductivity is suppressible in the magnetic field up to 2 Tesla.Comment: 11 pages, 4 figure
Conservation of connectivity of model-space effective interactions under a class of similarity transformation
Effective interaction operators usually act on a restricted model space and
give the same energies (for Hamiltonian) and matrix elements (for transition
operators etc.) as those of the original operators between the corresponding
true eigenstates. Various types of effective operators are possible. Those well
defined effective operators have been shown being related to each other by
similarity transformation. Some of the effective operators have been shown to
have connected-diagram expansions. It is shown in this paper that under a class
of very general similarity transformations, the connectivity is conserved. The
similarity transformation between hermitian and non-hermitian
Rayleigh-Schr\"{o}dinger perturbative effective operators is one of such
transformation and hence the connectivity can be deducted from each other.Comment: 12 preprint page
TSG-6 Downregulates IFN-Alpha and TNF-Alpha Expression by Suppressing IRF7 Phosphorylation in Human Plasmacytoid Dendritic Cells
Proinflammatory cytokines such as TNF-α and type I interferons (IFN) are pathogenic signatures of systemic lupus erythematosus, and plasmacytoid dendritic cells (pDCs) play a major role by predominantly producing IFN-α. Given the rise of importance in identifying tumor necrosis stimulated gene 6 (TSG-6) as a key anti-inflammatory regulator, we investigate its function and its ability to counteract proinflammatory cytokine secretion by pDCs in vitro. CpG-A and R837 induced significant endogenous TSG-6 expression in the pDC cell-line GEN2.2. Following recombinant human TSG-6 treatment and CpG-A or R837 stimulation, significant reduction in IFN-α and TNF-α was observed in healthy donors’ pDCs, and the same phenomenon was confirmed in GEN2.2. By CD44 blocking assay, we deduced that the suppressive effect of TSG-6 is mediated by CD44, by reducing IRF-7 phosphorylation. Our findings suggest that TSG-6 and its downstream signalling pathway could potentially be targeted to modulate proinflammatory cytokine expression in pDCs
Evolution of electronic states in n-type copper oxide superconductor via electric double layer gating
Since the discovery of n-type copper oxide superconductors, the evolution of
electron- and hole-bands and its relation to the superconductivity have been
seen as a key factor in unveiling the mechanism of high-Tc superconductors. So
far, the occurrence of electrons and holes in n-type copper oxides has been
achieved by chemical doping, pressure, and/or deoxygenation. However, the
observed electronic properties are blurred by the concomitant effects such as
change of lattice structure, disorder, etc. Here, we report on successful
tuning the electronic band structure of n-type Pr2-xCexCuO4 (x = 0.15)
ultrathin films, via the electric double layer transistor technique. Abnormal
transport properties, such as multiple sign reversals of Hall resistivity in
normal and mixed states, have been revealed within an electrostatic field in
range of -2 V to +2 V, as well as varying the temperature and magnetic field.
In the mixed state, the intrinsic anomalous Hall conductivity invokes the
contribution of both electron and hole-bands as well as the energy dependent
density of states near the Fermi level. The two-band model can also describe
the normal state transport properties well, whereas the carrier concentrations
of electrons and holes are always enhanced or depressed simultaneously in
electric fields. This is in contrast to the scenario of Fermi surface
reconstruction by antiferromagnetism, where an anti-correlation between
electrons and holes is commonly expected. Our findings paint the picture where
Coulomb repulsion plays an important role in the evolution of the electronic
states in n-type cuprate superconductors.Comment: 4 figures, SI not included. Comments are welcom
Hawking Radiation for Scalar and Dirac Fields in Five Dimensional Dilatonic Black Hole via Anomalies
We study massive scalar fields and Dirac fields propagating in a five
dimensional dilatonic black hole background. We expose that for both fields the
physics can be describe by a two dimensional theory, near the horizon. Then, in
this limit, by applying the covariant anomalies method we find the Hawking flux
by restoring the gauge invariance and the general coordinate covariance, which
coincides with the flux obtained from integrating the Planck distribution for
fermions.Comment: 10 page
Resonance-Enhanced Multiphoton Ionization for Real-Time Monitoring of Trichloroethylene formed by Degradation of Tetrachloroethylene Using Zero-Valent Zinc
Resonance-enhanced multiphoton ionization (REMPI) is investigated as a potential technique for real-time monitoring of selected volatile organochloride compounds (VOCs). In a proof-of-concept experiment, the progress of the reductive-degradation of tetrachloroethylene (PCE) to trichloroethylene (TCE) by zero-valent zinc was monitored by REMPI measurements performed in the headspace above the PCE solution. Two-photon resonant REMPI spectra of TCE and PCE were recorded over the wavelength range 305–320 nm. The concentrations of PCE and TCE in the headspace were monitored by measurement of the ionization signal with 315.64- and 310.48-nm excitation for PCE and TCE, respectively. Calibration curves yielded a linear range of more than 2 orders of magnitude for both compounds. The REMPI headspace results agreed well with the solution-phase results from gas chromatography analysis, which was used for independent verification of the progress of the reaction
Distinct Migratory Properties of M1, M2, and Resident Macrophages Are Regulated by α\u3csub\u3ed\u3c/sub\u3eβ\u3csub\u3e2\u3c/sub\u3eand α\u3csub\u3em\u3c/sub\u3eβ\u3csub\u3e2\u3c/sub\u3eIntegrin-Mediated Adhesion
Chronic inflammation is essential mechanism during the development of cardiovascular and metabolic diseases. The outcome of diseases depends on the balance between the migration/accumulation of pro-inflammatory (M1) and anti-inflammatory (M2) macrophages in damaged tissue. The mechanism of macrophage migration and subsequent accumulation is still not fully understood. Currently, the amoeboid adhesion-independent motility is considered essential for leukocyte migration in the three-dimensional environment. We challenge this hypothesis by studying the contribution of leukocyte adhesive receptors, integrins αMβ2, and αDβ2, to three-dimensional migration of M1-polarized, M2-polarized, and resident macrophages. Both integrins have a moderate expression on M2 macrophages, while αDβ2 is upregulated on M1 and αMβ2 demonstrates high expression on resident macrophages. The level of integrin expression determines its contribution to macrophage migration. Namely, intermediate expression supports macrophage migration, while a high integrin density inhibits it. Using in vitro three-dimensional migration and in vivo tracking of adoptively-transferred fluorescently-labeled macrophages during the resolution of inflammation, we found that strong adhesion of M1-activated macrophages translates to weak 3D migration, while moderate adhesion of M2-activated macrophages generates dynamic motility. Reduced migration of M1 macrophages depends on the high expression of αDβ2, since αD-deficiency decreased M1 macrophage adhesion and improved migration in fibrin matrix and peritoneal tissue. Similarly, the high expression of αMβ2 on resident macrophages prevents their amoeboid migration, which is markedly increased in αM-deficient macrophages. In contrast, αD- and αM-knockouts decrease the migration of M2 macrophages, demonstrating that moderate integrin expression supports cell motility. The results were confirmed in a diet-induced diabetes model. αD deficiency prevents the retention of inflammatory macrophages in adipose tissue and improves metabolic parameters, while αM deficiency does not affect macrophage accumulation. Summarizing, β2 integrin-mediated adhesion may inhibit amoeboid and mesenchymal macrophage migration or support mesenchymal migration in tissue, and, therefore, represents an important target to control inflammation
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