246 research outputs found
Interplay of linear and nonlinear impurities in the formation of stationary localized states
Formation of stationary localized states in one-dimensional chain as well as
in a Cayley tree due to a linear impurity and a nonlinear impurity is studied.
Furthermore, a one-dimensional chain with linear and nonlinear site energies at
the alternate sites is studied and rich phase diagrams of SL states are
obtained for all systems we considered. The results are compared with those of
the linear and nonlinear systems.Comment: 7 pages, Latex, 7 figure
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Tubular solid oxide fuel cell commercialization program
Developing clean, efficient, and cost effective technologies for future power generation is essential to meeting the world`s energy needs, while helping to clean up pollution and conserve valuable natural resources. Westinghouse is pioneering the development of solid oxide fuel cell (SOFC) technology as one of the promising technologies that will lead the world into a new generation of power production. The Westinghouse SOFC consists of tubular cells that can utilize fuels such as natural gas, coal derived fuel gas, biomass gas, and distillate fuels. Besides fuel flexibility, tubular SOFCs promise very high efficiencies, low cost, low plant maintenance, and ease of operation, and they have already demonstrated essentially no acid rain pollutants
Tumor infiltrating effector memory Antigen-Specific CD8+ T Cells predict response to immune checkpoint therapy
Immune checkpoint therapy (ICT) results in durable responses in individuals with some cancers, but not all patients respond to treatment. ICT improves CD8+ cytotoxic T lymphocyte (CTL) function, but changes in tumor antigen-specific CTLs post-ICT that correlate with successful responses have not been well characterized. Here, we studied murine tumor models with dichotomous responses to ICT. We tracked tumor antigen-specific CTL frequencies and phenotype before and after ICT in responding and non-responding animals. Tumor antigen-specific CTLs increased within tumor and draining lymph nodes after ICT, and exhibited an effector memory-like phenotype, expressing IL-7R (CD127), KLRG1, T-bet, and granzyme B. Responding tumors exhibited higher infiltration of effector memory tumor antigen-specific CTLs, but lower frequencies of regulatory T cells compared to non-responders. Tumor antigen-specific CTLs persisted in responding animals and formed memory responses against tumor antigens. Our results suggest that increased effector memory tumor antigen-specific CTLs, in the presence of reduced immunosuppression within tumors is part of a successful ICT response. Temporal and nuanced analysis of T cell subsets provides a potential new source of immune based biomarkers for response to ICT
Mapping the Two-Component Atomic Fermi Gas to the Nuclear Shell-Model
The physics of a two-component cold fermi gas is now frequently addressed in
laboratories. Usually this is done for large samples of tens to hundreds of
thousands of particles. However, it is now possible to produce few-body systems
(1-100 particles) in very tight traps where the shell structure of the external
potential becomes important. A system of two-species fermionic cold atoms with
an attractive zero-range interaction is analogous to a simple model of nucleus
in which neutrons and protons interact only through a residual pairing
interaction. In this article, we discuss how the problem of a two-component
atomic fermi gas in a tight external trap can be mapped to the nuclear shell
model so that readily available many-body techniques in nuclear physics, such
as the Shell Model Monte Carlo (SMMC) method, can be directly applied to the
study of these systems. We demonstrate an application of the SMMC method by
estimating the pairing correlations in a small two-component Fermi system with
moderate-to-strong short-range two-body interactions in a three-dimensional
harmonic external trapping potential.Comment: 13 pages, 3 figures. Final versio
Recent Advances in Understanding Particle Acceleration Processes in Solar Flares
We review basic theoretical concepts in particle acceleration, with
particular emphasis on processes likely to occur in regions of magnetic
reconnection. Several new developments are discussed, including detailed
studies of reconnection in three-dimensional magnetic field configurations
(e.g., current sheets, collapsing traps, separatrix regions) and stochastic
acceleration in a turbulent environment. Fluid, test-particle, and
particle-in-cell approaches are used and results compared. While these studies
show considerable promise in accounting for the various observational
manifestations of solar flares, they are limited by a number of factors, mostly
relating to available computational power. Not the least of these issues is the
need to explicitly incorporate the electrodynamic feedback of the accelerated
particles themselves on the environment in which they are accelerated. A brief
prognosis for future advancement is offered.Comment: This is a chapter in a monograph on the physics of solar flares,
inspired by RHESSI observations. The individual articles are to appear in
Space Science Reviews (2011
Amazon Basin forest pyrogenic carbon stocks: First estimate of deep storage
Amazon Basin forest soils contain considerable soil organic carbon stocks; however, the contribution of soil pyrogenic carbon (PyC) to the total is unknown. PyC is derived from local fires (historical and modern) and external inputs via aeolian deposition. To establish an initial estimate of PyC stocks in non-terra preta forest with no known history of fire, to assess site and vertical variability, as well as to determine optimal sampling design, we sampled 37 one hectare forest plots in the Amazon Basin and analysed PyC via hydrogen pyrolysis of three individual samples per plot and of bulked samples to 200 cm depth. Using our data and published total organic carbon stocks, we present the first field-based estimate of total PyC stock for the Amazon Basin of 1.10 Pg over 0–30 cm soil depth, and 2.76 Pg over 0–100 cm soil depth. This is up to 20 times higher than previously assumed. Three individual samples per 1 ha are sufficient to capture the site variability of PyC in our plots. PyC showed significant, large-scale variability among plots. To capture 50% of the PyC in 200 cm soil profiles, soil must be sampled to a depth of at least 71 cm. PyC represents a significant (11%) portion of total organic carbon in soil profiles 0–200 cm depth. This finding highlights the potentially important role that historical fire has played in modifying soil C stocks. Our data suggest that PyC is an important carbon pool for long-term storage, involved in millennial scale biogeochemical cycling, particularly in the subsurface soil
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