2,917 research outputs found
A Study of Meteoroid Impact Phenomena
Process of crater formation resulting from impact of hypervelocity projectile - meteoroid impac
Improving impact resistance of ceramic materials by energy absorbing surface layers
Energy absorbing surface layers were used to improve the impact resistance of silicon nitride and silicon carbide ceramics. Low elastic modulus materials were used. In some cases, the low elastic modulus was achieved using materials that form localized microcracks as a result of thermal expansion anisotropy, thermal expansion differences between phases, or phase transformations. In other cases, semi-vitreous or vitreous materials were used. Substantial improvements in impact resistance were observed at room and elevated temperatures
Spatially distributed water-balance and meteorological data from the Wolverton catchment, Sequoia National Park, California
Accurate water-balance measurements in the seasonal, snow-dominated Sierra Nevada are important for forest and downstream water management. However, few sites in the southern Sierra offer detailed records of the spatial and temporal patterns of snowpack and soil-water storage and the fluxes affecting them, i.e., precipitation as rain and snow, snowmelt, evapotranspiration, and runoff. To explore these stores and fluxes we instrumented the Wolverton basin (2180-2750 m) in Sequoia National Park with distributed, continuous sensors. This 2006-2016 record of snow depth, soil moisture and soil temperature, and meteorological data quantifies the hydrologic inputs and storage in a mostly undeveloped catchment. Clustered sensors record lateral differences with regards to aspect and canopy cover at approximately 2250 and 2625 m in elevation, where two meteorological stations are installed. Meteorological stations record air temperature, relative humidity, radiation, precipitation, wind speed and direction, and snow depth. Data are available at hourly intervals by water year (1 October-30 September) in non-proprietary formats from online data repositories (https://doi.org/10.6071/M3S94T)
Strengthening of oxidation resistant materials for gas turbine applications
Silicon nitride and silicon carbide ceramics were treated to form compressive surface layers. On the silicon carbide, quenching and thermal exposure treatments were used, and on the silicon nitride, quenching, carburizing, and a combination of quenching and carburizing were used. In some cases substantial improvements in impact resistance and/or flexural strength were observed. The presence of compressive surface stresses was demonstrated by slotted rod tests
Continuous-Time Monte Carlo study of the pseudogap Bose-Fermi Kondo model
We study the pseudogap Bose-Fermi Anderson model with a continuous-time
quantum Monte Carlo (CT-QMC) method. We discuss some delicate aspects of the
transformation from this model to the Bose-Fermi Kondo model. We show that the
CT-QMC method can be used at sufficiently low temperatures to access the
quantum critical properties of these models.Comment: SCES 2010 Proceeding
Announcing the Officers of the Faculty Forum
News release announcing the officers of the Faculty Forum at the University of Dayton
Hepatic progenitor cells from adult human livers for cell transplantation.
Objective: Liver regeneration is mainly based on cellular
self-renewal including progenitor cells. Efforts have been
made to harness this potential for cell transplantation, but
shortage of hepatocytes and premature differentiated
progenitor cells from extra-hepatic organs are limiting
factors. Histological studies implied that resident cells in
adult liver can proliferate, have bipotential character and
may be a suitable source for cell transplantation.
Methods: Particular cell populations were isolated after
adequate tissue dissociation. Single cell suspensions were
purified by Thy-1 positivity selection, characterised in vitro
and transplanted in immunodeficient Pfp/Rag2 mice.
Results: Thy-1+ cells that are mainly found in the portal
tract and the surrounding parenchyma, were isolated from
surgical liver tissue with high yields from specimens with
histological signs of regeneration. Thy-1+ cell populations
were positive for progenitor (CD34, c-kit, CK14, M2PK,
OV6), biliary (CK19) and hepatic (HepPar1) markers
revealing their progenitor as well as hepatic and biliary
nature. The potential of Thy-1+ cells for differentiation in
vitro was demonstrated by increased mRNA and protein
expression for hepatic (CK18, HepPar1) and biliary (CK7)
markers during culture while progenitor markers CK14,
chromogranin A and nestin were reduced. After
transplantation of Thy-1+ cells into livers of immunodeficient
mice, engraftment was predominantly seen in the
periportal portion of the liver lobule. Analysis of in situ
material revealed that transplanted cells express human
hepatic markers HepPar1 and albumin, indicating functional
engraftment.
Conclusion: Bipotential progenitor cells from human
adult livers can be isolated using Thy-1 and might be a
potential candidate for cell treatment in liver diseases
Supersymmetric Yang-Mills theory on the lattice
Recent development in numerical simulations of supersymmetric Yang-Mills
(SYM) theories on the lattice is reviewed.Comment: 37 pages, 10 figure
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