4,844 research outputs found
The second critical point for the Perfect Bose gas in quasi-one-dimensional traps
We present a new model of quasi-one-dimensional trap with some unknown
physical predictions about a second transition, including about a change in
fractions of condensed coherence lengths due to the existence of a second
critical temperature Tm < Tc. If this physical model is acceptable, we want to
challenge experimental physicists in this regard
Scaling-up quantum heat engines efficiently via shortcuts to adiabaticity
The finite-time operation of a quantum heat engine that uses a single
particle as a working medium generally increases the output power at the
expense of inducing friction that lowers the cycle efficiency. We propose to
scale up a quantum heat engine utilizing a many-particle working medium in
combination with the use of shortcuts to adiabaticity to boost the nonadiabatic
performance by eliminating quantum friction and reducing the cycle time. To
this end, we first analyze the finite-time thermodynamics of a quantum Otto
cycle implemented with a quantum fluid confined in a time-dependent harmonic
trap. We show that nonadiabatic effects can be controlled and tailored to match
the adiabatic performance using a variety of shortcuts to adiabaticity. As a
result, the nonadiabatic dynamics of the scaled-up many-particle quantum heat
engine exhibits no friction and the cycle can be run at maximum efficiency with
a tunable output power. We demonstrate our results with a working medium
consisting of particles with inverse-square pairwise interactions, that
includes noninteracting and hard-core bosons as limiting cases.Comment: 15 pages, 3 figures; typo in Eq. (51) fixed. Feature paper in the
Special Issue "Quantum Thermodynamics" edited by Prof. Dr. Ronnie Koslof
Using Multiattribute Utility Copulas in Support of UAV Search and Destroy Operations
The multiattribute utility copula is an emerging form of utility function used by decision analysts to study decisions with dependent attributes. Failure to properly address attribute dependence may cause errors in selecting the optimal policy. This research examines two scenarios of interest to the modern warfighter. The first scenario employs a utility copula to determine the type, quantity, and altitude of UAVs to be sent to strike a stationary target. The second scenario employs a utility copula to examine the impact of attribute dependence on the optimal routing of UAVs in a contested operational environment when performing a search and destroy mission against a Markovian target. Routing decisions involve a tradeoff between risk of UAV exposure to the enemy and the ability to strike the target. This research informs decision makers and analysts with respect to the tactics, techniques, and procedures employed in UAV search and destroy missions. An ever increasing UAV operations tempo suggests such research becoming increasingly relevant to the warfighter
Statistical Inference to Evaluate and Compare the Performance of Correlated Multi-State Classification Systems
The current emphasis on including correlation when comparing diagnostic test performance is quite important, however, there are cases in which correlation effects may be negligible with respect to inference. This proposed work examines the impact of including correlation between classification systems with continuous features by comparing the optimal performance of two diagnostic tests with multiple outcomes as well as providing inference for a sequence of tests. We define the optimal point using Bayes Cost, a metric that sums the weighted misclassifications within a diagnostic test using a cost/benefit structure. Through simulation, we quantify the impact of correlation on standard errors comparing two tests and evaluate the resulting errors with respect to CI coverage and width under varying diagnostic test accuracy, sample size, cost/benefit structures, parametric assumptions and correlation levels. When formulas are required for better inference to include correlation, we provide updated computational techniques that properly extend the Delta and Generalized method. Additionally, to date, no methods have been applied to quantify the performance of a sequence of tests. Therefore, the inference methods derived in this work are extended to sequenced tests where feature correlation is unavoidable and must be accounted for when developing inference on tests
Clathrate formation and dissociation in vapor/water/ice/hydrate systems in SBA-15, sol-gel and CPG porous media, as probed by NMR relaxation, novel protocol NMR cryoporometry, neutron scattering and ab initio quantum-mechanical molecular dynamics simulation
The Gibbs-Thomson effect modifies the pressure and temperature at which clathrates occur, hence altering the depth at which they occur in the seabed. Nuclear magnetic resonance (NMR) measurements as a function of temperature are being conducted for water/ice/ hydrate systems in a range of pore geometries, including templated SBA-15 silicas, controlled pore glasses and sol-gel silicas. Rotator-phase plastic ice is shown to be present in confined geometry, and bulk tetrahydrofuran hydrate is also shown to probably have a rotator phase. A novel NMR cryoporometry protocol, which probes both melting and freezing events while avoiding the usual problem of supercooling for the freezing event, has been developed. This enables a detailed probing of the system for a given pore size and geometry and the exploration of differences between hydrate formation and dissociation processes inside pores. These process differences have an important effect on the environment, as they impact on the ability of a marine hydrate system to re-form once warmed above a critical temperature. Ab initio quantum-mechanical molecular dynamics calculations are also being employed to probe the dynamics of liquids in pores at nanometric dimensions
The clathrin-binding domain of CALM-AF10 alters the phenotype of myeloid neoplasms in mice.
The PICALM (CALM) gene, whose product is involved in clathrin-mediated endocytosis, has been identified in two recurring chromosomal translocations, involving either MLL or MLLT10 (AF10). We developed a mouse model of CALM-AF10(+) leukemia to examine the hypothesis that disruption of endocytosis contributes to leukemogenesis. Exclusion of the C-terminal portion of CALM from the fusion protein, which is required for optimal binding to clathrin, resulted in the development of a myeloproliferative disease, whereas inclusion of this domain led to the development of acute myeloid leukemia and changes in gene expression of several cancer-related genes, notably Pim1 and Crebbp. Nonetheless, the development of leukemia could not be attributed directly to interference with endocytosis or consequential changes in proliferation and signaling. In leukemia cells, full-length CALM-AF10 localized to the nucleus with no consistent effect on growth factor endocyctosis, and suppressed histone H3 lysine 79 methylation regardless of the presence of clathrin. Using fluorescence resonance energy transfer analysis, we show that CALM-AF10 has a propensity to homo-oligomerize, raising the possibility that the function of endocytic proteins involved in chimeric fusions may be to provide dimerization properties, a recognized mechanism for unleashing oncogenic properties of chimeric transcription factors, rather than disrupting the internalization of growth factor receptors
- …