583 research outputs found
Position-sensitive detector for the 6-meter optical telescope
The Position-Sensitive Detector (PSD) for photometrical and spectral
observation on the 6-meter optical telescope of the Special Astrophysical
Observatory (Russia) is described. The PSD consists of a position-sensitive
tube, amplifiers of output signals, analog-to-digital converters (ADC) and a
digital logic plate, which produces a signal for ADC start and an external
strob pulse for reading information by registration system. If necessary, the
thermoelectric cooler can be used. The position-sensitive tube has the
following main elements: a photocathode, electrodes of inverting optics, a
block of microchannel plates (MCP) and a position-sensitive collector of
quadrant type. The main parameters of the PSD are the diameter of the sensitive
surface is 25 mm, the spatial resolution is better than 100 (\mu)m in the
centre and a little worse on the periphery; the dead time is near 0.5 (\mu)s;
the detection quantum efficiency is defined by the photocathode and it is not
less than 0.1, as a rule; dark current is about hundreds of cps, or less, when
cooling. PSD spectral sensitivity depends on the type of photocathode and input
window material. We use a multialkali photocathode and a fiber or UV-glass,
which gives the short- wave cut of 360 nm or 250 nm, respectively.Comment: 4 pages, 7 figures, to be published in Nuclear Instruments & Methods
in Physics Researc
The Effect of Transfer Printing on Pentacene Thin-Film Crystal Structure
The thermal deposition and transfer Printing method had been used to produce
pentacene thin-films on SiO2/Si and plastic substrates (PMMA and PVP),
respectively. X-ray diffraction patterns of pentacene thin films showed
reflections associated with highly ordered polycrystalline films and a
coexistence of two polymorph phases classified by their d-spacing, d(001): 14.4
and 15.4 A.The dependence of the c-axis correlation length and the phase
fraction on the film thickness and printing temperature were measured. A
transition from the 15.4 A phase towards 14.4 A phase was also observed with
increasing film thickness. An increase in the c-axis correlation length of
approximately 12% ~16% was observed for Pn films transfer printed onto a PMMA
coated PET substrate at 100~120 C as compared to as-grown Pn films on SiO2/Si
substrates. The transfer printing method is shown to be an attractive for the
fabrication of pentacene thin-film transistors on flexible substrates partly
because of the resulting improvement in the quality of the pentacene film.Comment: 5 pages, 5 figure
Excitonic transitions in GaAs-AlxGa1-xAs multiple quantum wells affected by interface roughness
Time-resolved photoluminescence has been used to study the effects of interface roughness on excitonic transitions in GaAs-AlxGa1-xAs multiple quantum wells. In addition to the luminescence linewidth broadening and Stokes red shift, the interface roughness also strongly affects the dynamic process of optical transitions so that the excitonic transition peak shifts with delay time. However, the heavy-hole exciton transition has red shifts at short delay times and exhibits a turnover at longer delay times. A maximum shift of about 0.1 meV at a delay time of 4 ns was obtained. We have demonstrated that the peak shift is caused by interface roughness in the quantum wells. Furthermore, the decay of the excitonic transition is found to fit a two-exponential form. Based on a model involving interface roughness and two-exponential decay, we calculated the position of the excitonic transition peak as a function of delay time. Our calculations are consistent with experimental results
Topical Administration of SLN-Based Gene Therapy for the Treatment of Corneal Inflammation by De Novo IL-10 Production
The effect of dalargin on growth factors content in experimental ulcerative colitis
The aim of the study was to evaluate the dalargin effect on the content of transforming growth factor-β (TGF-β) and epidermal growth factor (EGF) in the colonic wall in mice with experimental ulcerative coliti
Renormalization-group study of Anderson and Kondo impurities in gapless Fermi systems
Thermodynamic properties are presented for four magnetic impurity models
describing delocalized fermions scattering from a localized orbital at an
energy-dependent rate which vanishes precisely at the Fermi
level, . Specifically, it is assumed that for small ,
with . The cases and
describe dilute magnetic impurities in unconventional superconductors, ``flux
phases'' of the two-dimensional electron gas, and zero-gap semiconductors. For
the nondegenerate Anderson model, the depression of the low-energy scattering
rate suppresses mixed valence in favor of local-moment behavior, and leads to a
marked reduction in the exchange coupling on entry to the local-moment regime,
with a consequent narrowing of the range of parameters within which the
impurity spin becomes Kondo-screened. The relationship between the Anderson
model and the exactly screened Kondo model with power-law exchange is examined.
The intermediate-coupling fixed point identified in the latter model by Withoff
and Fradkin (WF) has clear signatures in the thermodynamic properties and in
the local magnetic response of the impurity. The underscreened,
impurity-spin-one Kondo model and the overscreened, two-channel Kondo model
both exhibit a conditionally stable intermediate-coupling fixed point in
addition to unstable fixed points of the WF type. In all four models, the
presence or absence of particle-hole symmetry plays a crucial role.Comment: 44 two-column REVTex pages, 31 epsf-embedded EPS figures. MINOR
formatting changes. To appear in Phys. Rev.
Central memory phenotype drives success of checkpoint inhibition in combination with CAR T cells
The immunosuppressive microenvironment in solid tumors is thought to form a barrier to the entry and efficacy of cell-based therapies such as chimeric antigen receptor (CAR) T cells. Combining CAR T cell therapy with checkpoint inhibitors has been demonstrated to oppose immune escape mechanisms in solid tumors and augment antitumor efficacy. We evaluated PD-1/PD-L1 signaling capacity and the impact of an inhibitor of this checkpoint axis in an in vitro system for cancer cell challenge, the coculture of L1CAM-specific CAR T cells with neuroblastoma cell lines. Fluorescence-activated cell sorting-based analyses and luciferase reporter assays were used to assess PD-1/PD-L1 expression on CAR T and tumor cells as well as CAR T cell ability to kill neuroblastoma cells. Coculturing neuroblastoma cell lines with L1CAM-CAR T cells upregulated PD-L1 expression on neuroblastoma cells, confirming adaptive immune resistance. Exposure to neuroblastoma cells also upregulated the expression of the PD-1/PD-L1 axis in CAR T cells. The checkpoint inhibitor, nivolumab, enhanced L1CAM-CAR T cell-directed killing. However, nivolumab-enhanced L1CAM-CAR T cell killing did not strictly correlate with PD-L1 expression on neuroblastoma cells. In fact, checkpoint inhibitor success relied on strong PD-1/PD-L1 axis expression in the CAR T cells, which in turn depended on costimulatory domains within the CAR construct, and more importantly, on the subset of T cells selected for CAR T cell generation. Thus, T cell subset selection for CAR T cell generation and CAR T cell prescreening for PD-1/PD-L1 expression could help determine when combination therapy with checkpoint inhibitors could improve treatment efficacy
Probing Mechanical Properties of Graphene with Raman Spectroscopy
The use of Raman scattering techniques to study the mechanical properties of
graphene films is reviewed here. The determination of Gruneisen parameters of
suspended graphene sheets under uni- and bi-axial strain is discussed and the
values are compared to theoretical predictions. The effects of the
graphene-substrate interaction on strain and to the temperature evolution of
the graphene Raman spectra are discussed. Finally, the relation between
mechanical and thermal properties is presented along with the characterization
of thermal properties of graphene with Raman spectroscopy.Comment: To appear in the Journal of Materials Scienc
Spintronics: Fundamentals and applications
Spintronics, or spin electronics, involves the study of active control and
manipulation of spin degrees of freedom in solid-state systems. This article
reviews the current status of this subject, including both recent advances and
well-established results. The primary focus is on the basic physical principles
underlying the generation of carrier spin polarization, spin dynamics, and
spin-polarized transport in semiconductors and metals. Spin transport differs
from charge transport in that spin is a nonconserved quantity in solids due to
spin-orbit and hyperfine coupling. The authors discuss in detail spin
decoherence mechanisms in metals and semiconductors. Various theories of spin
injection and spin-polarized transport are applied to hybrid structures
relevant to spin-based devices and fundamental studies of materials properties.
Experimental work is reviewed with the emphasis on projected applications, in
which external electric and magnetic fields and illumination by light will be
used to control spin and charge dynamics to create new functionalities not
feasible or ineffective with conventional electronics.Comment: invited review, 36 figures, 900+ references; minor stylistic changes
from the published versio
Ductal carcinoma in situ of the breast, a population-based study of epidemiology and pathology
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