323 research outputs found
Optical Simulation of Antenna Images
Control Systems Laboratory changed its name to Coordinated Science LaboratoryContract DA-36-039-SC-5669
Surface Tension between Kaon Condensate and Normal Nuclear Matter Phase
We calculate for the first time the surface tension and curvature coefficient
of a first order phase transition between two possible phases of cold nuclear
matter, a normal nuclear matter phase in equilibrium with a kaon condensed
phase, at densities a few times the saturation density. We find the surface
tension is proportional to the difference in energy density between the two
phases squared. Furthermore, we show the consequences for the geometrical
structures of the mixed phase region in a neutron star.Comment: 7 pages, 5 figures (Latex
Systematic study of Oxygen vacancy tunable transport properties of few-layer MoO3- x enabled by vapor-based synthesis
Bulk and nanoscale molybdenum trioxide (MoO3) has shown impressive technologically relevant properties, but deeper investigation into 2D MoO3 has been prevented by the lack of reliable vapor-based synthesis and doping techniques. Herein, the successful synthesis of high-quality, few-layer MoO3 down to bilayer thickness via physical vapor deposition is reported. The electronic structure of MoO3 can be strongly modified by introducing oxygen substoichiometry (MoO3- x), which introduces gap states and increases conductivity. A dose-controlled electron irradiation technique to introduce oxygen vacancies into the few-layer MoO3 structure is presented, thereby adding n-type doping. By combining in situ transport with core-loss and monochromated low-loss scanning transmission electron microscopy–electron energy-loss spectroscopy studies, a detailed structure–property relationship is developed between Mo-oxidation state and resistance. Transport properties are reported for MoO3- x down to three layers thick, the most 2D-like MoO3- x transport hitherto reported. Combining these results with density functional theory calculations, a radiolysis-based mechanism for the irradiation-induced oxygen vacancy introduction is developed, including insights into favorable configurations of oxygen defects. These systematic studies represent an important step forward in bringing few-layer MoO3 and MoO3- x into the 2D family, as well as highlight the promise of MoO3- x as a functional, tunable electronic material
Brownian motion in AdS/CFT
We study Brownian motion and the associated Langevin equation in AdS/CFT. The
Brownian particle is realized in the bulk spacetime as a probe fundamental
string in an asymptotically AdS black hole background, stretching between the
AdS boundary and the horizon. The modes on the string are excited by the
thermal black hole environment and consequently the string endpoint at the
boundary undergoes an erratic motion, which is identified with an external
quark in the boundary CFT exhibiting Brownian motion. Semiclassically, the
modes on the string are thermally excited due to Hawking radiation, which
translates into the random force appearing in the boundary Langevin equation,
while the friction in the Langevin equation corresponds to the excitation on
the string being absorbed by the black hole. We give a bulk proof of the
fluctuation-dissipation theorem relating the random force and friction. This
work can be regarded as a step toward understanding the quantum microphysics
underlying the fluid-gravity correspondence. We also initiate a study of the
properties of the effective membrane or stretched horizon picture of black
holes using our bulk description of Brownian motion.Comment: 54 pages (38 pages + 5 appendices), 5 figures. v2: references added,
clarifications in 6.2. v3: clarifications, version submitted to JHE
Radiating black hole solutions in arbitrary dimensions
We prove a theorem that characterizes a large family of non-static solutions
to Einstein equations in -dimensional space-time, representing, in general,
spherically symmetric Type II fluid. It is shown that the best known
Vaidya-based (radiating) black hole solutions to Einstein equations, in both
four dimensions (4D) and higher dimensions (HD), are particular cases from this
family. The spherically symmetric static black hole solutions for Type I fluid
can also be retrieved. A brief discussion on the energy conditions,
singularities and horizons is provided.Comment: RevTeX 9 pages, no figure
Black Holes in Higher-Dimensional Gravity
These lectures review some of the recent progress in uncovering the phase
structure of black hole solutions in higher-dimensional vacuum Einstein
gravity. The two classes on which we focus are Kaluza-Klein black holes, i.e.
static solutions with an event horizon in asymptotically flat spaces with
compact directions, and stationary solutions with an event horizon in
asymptotically flat space. Highlights include the recently constructed
multi-black hole configurations on the cylinder and thin rotating black rings
in dimensions higher than five. The phase diagram that is emerging for each of
the two classes will be discussed, including an intriguing connection that
relates the phase structure of Kaluza-Klein black holes with that of
asymptotically flat rotating black holes.Comment: latex, 49 pages, 5 figures. Lectures to appear in the proceedings of
the Fourth Aegean Summer School, Mytiline, Lesvos, Greece, September 17-22,
200
Morphology and foliar chemistry of containerized Abies fraseri (Pursh) Poir. seedlings as affected by water availability and nutrition
• We present the results of a two-year (2007–2008) greenhouse study investigating the
effect of water availability and nitrogen fertilization on the growth, biomass
partitioning, and foliar nutrient content of Abies fraseri (Pursh)
Poir.
• Fertilizer and moisture content (irrigation) were varied in a factorial experiment
combining four levels of irrigation and three levels of fertilization to evaluate growth
and foliar nutrient content. In addition, a numerical optimization was used to estimate
appropriate levels of each factor necessary to achieve simulated goals for response
variables.
• Irrigation increased the height growth by 12 to 35% depending on the fertilization
treatment (p = 0.0001). Fertilization increased height growth by 10 to
26% (p = 0.02). A similar response was observed for stem diameter growth
(SDG). Total biomass accumulation increased as result of positive response of stem and
root biomass development, and foliar nitrogen content was positively affected by nitrogen
fertilization and negatively affected by irrigation. The numerical optimization for
simulated target growth and nitrogen content responses produced levels of input
combinations with high desirability factors to achieve the target responses.
• These results suggest that nutrient addition is a strong determining factor for early
development of this species. The improved growth efficiency in this study is likely
attributed to a combination of factors including, improved photosynthetic capacity,
decreased stomatal limitations, or increased resource allocation to stems
n-Hexadecane hydrocracking Single-Event MicroKinetics on Pt/H-beta
[EN] The Single-Event MicroKinetic (SEMK) model constructed for gas-phase hydroconversion of light n-alkanes on large-pore USY zeolites was applied, for the first time, to the hydrocracking of n-hexadecane on a Pt/H-Beta catalyst. Despite the 12-ringed pore channels, shape selectivity was observed in the formation of ethyl side chains. Additionally, heavy feed molecules such as n-hexadecane lead to physisorption saturation of the catalyst pores by strong Van der Waals interactions of the long alkyl chains with the zeolite framework. Intermolecular interactions and packing efficiencies in the pores induce deviations from typical Henry-regime physisorption characteristics as the physisorption selectivity, which is expected to increase with increasing carbon number, appeared to be independent of the latter. Micropore saturation effects were described by the 'size entropy' which quantifies the difference in standard entropy loss between physisorption in the Henry regime and hindered physisorption on a saturated surface. The size entropy is proportional to the catalyst loading with physisorbed species and the adsorbate carbon number. The addition of a size entropy term in the SEMK model, amounting to 102J mol(-1) K-1 for a hexadecane molecule at full saturation, allowed accurately reproducing the contribution of secondary isomerization and cracking reactions, as quantified by means of a contribution analysis. (C) 2012 Elsevier B.V. All rights reserved.This work was funded by the European Research Institute of
Catalysis and the European Community’s Sixth Framework Programme. This work was also supported by the Research Board
of Ghent University (BOF), the Interuniversity Attraction Poles
Programme–Belgian State–Belgian Science Policy and the Long
Term Structural Methusalem Funding by the Flemish Government.
Financial support by the ComisiĂłn Interministerial de Ciencia y TecnologĂa (CICYT) of Spain through the Project CTQ2010-17988/PPQ
is also gratefully acknowledged.Vandegehuchte, BD.; Thybaut, JW.; Martinez Feliu, A.; Arribas Viana, MDLD.; Marin, GB. (2012). n-Hexadecane hydrocracking Single-Event MicroKinetics on Pt/H-beta. Applied Catalysis A General. 441:10-20. doi:10.1016/j.apcata.2012.06.054S102044
Understanding preventive behaviors among mid-Western African-American men: a pilot qualitative study of prostate screening
http://dx.doi.org/10.1016/j.jomh.2011.03.00
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
- …