6,764 research outputs found
The Cauchy problem for the Pavlov equation
Commutation of multidimensional vector fields leads to integrable nonlinear
dispersionless PDEs arising in various problems of mathematical physics and
intensively studied in the recent literature. This report is aiming to solve
the scattering and inverse scattering problem for integrable dispersionless
PDEs, recently introduced just at a formal level, concentrating on the
prototypical example of the Pavlov equation, and to justify an existence
theorem for global bounded solutions of the associated Cauchy problem with
small data.Comment: In the new version the analytical technique was essentially revised.
The previous version contained a wrong statement about the solvability of the
inverse problem for large data. This problem remains ope
Microscopic theory of multipole ordering in NpO2
In order to examine the mysterious ordered phase of NpO2 from a microscopic
viewpoint, we investigate an f-electron model on an fcc lattice constructed
based on a j-j coupling scheme. First, an effective model with multipole
interactions is derived in the strong-coupling limit. Numerical analysis of the
model clearly indicates that the interactions for \Gamma_{4u} and \Gamma_{5u}
moments are relevant to the ground state. Then, by applying mean-field theory
to the simplified model including only such interactions, we conclude that
longitudinal triple-q \Gamma_{5u} octupole order is realized in NpO2 through
the combined effects of multipole interactions and anisotropy of the
\Gamma_{5u} moment.Comment: 5 pages, 2 figure
Economic and demographic issues related to deployment of the Satellite Power System (SPS)
Growth in energy consumption stimulated interest in exploitation of renewable sources of electric energy. One technology that was proposed is the Satellite Power System (SPS). Before committing the U.S. to such a large program, the Department of Energy and the National Aeronautics and Space Administration are jointly participating in an SPS Concept Development and Evaluation Program. This white paper on industrial and population relocation is part of the FY 78 preliminary evaluation of related socio-economic issues. Results of four preliminary assessment activities are documented
The PEP Survey: Infrared Properties of Radio-Selected AGN
By exploiting the VLA-COSMOS and the Herschel-PEP surveys, we investigate the
Far Infrared (FIR) properties of radio-selected AGN. To this purpose, from
VLA-COSMOS we considered the 1537, F[1.4 GHz]>0.06 mJy sources with a reliable
redshift estimate, and sub-divided them into star-forming galaxies and AGN
solely on the basis of their radio luminosity. The AGN sample is complete with
respect to radio selection at all z<~3.5. 832 radio sources have a counterpart
in the PEP catalogue. 175 are AGN. Their redshift distribution closely
resembles that of the total radio-selected AGN population, and exhibits two
marked peaks at z~0.9 and z~2.5. We find that the probability for a
radio-selected AGN to be detected at FIR wavelengths is both a function of
radio power and redshift, whereby powerful sources are more likely to be FIR
emitters at earlier epochs. This is due to two distinct effects: 1) at all
radio luminosities, FIR activity monotonically increases with look-back time
and 2) radio activity of AGN origin is increasingly less effective at
inhibiting FIR emission. Radio-selected AGN with FIR emission are
preferentially located in galaxies which are smaller than those hosting
FIR-inactive sources. Furthermore, at all z<~2, there seems to be a
preferential (stellar) mass scale M ~[10^{10}-10^{11}] Msun which maximizes the
chances for FIR emission. We find such FIR (and MIR) emission to be due to
processes indistinguishable from those which power star-forming galaxies. It
follows that radio emission in at least 35% of the entire AGN population is the
sum of two contributions: AGN accretion and star-forming processes within the
host galaxy.Comment: 13 pages, 14 figures, to appear in MNRA
A new player in the development of TRAIL based therapies for hepatocarcinoma treatment: ATM kinase
Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. HCCs are genetically and phenotypically heterogeneous tumors characterized by very poor prognosis, mainly due to the lack, at present, of effective therapeutic options, as these tumors are rarely suitable for radiotherapy and often resistant to chemotherapy protocols. In the last years, agonists targeting the Tumor Necrosis Factor Related Apoptosis Inducing Ligand (TRAIL) death receptor, has been investigated as a valuable promise for cancer therapy, based on their selectivity for malignant cells and low toxicity for healthy cells. However, many cancer models display resistance to death receptor induced apoptosis, pointing to the requirement for the development of combined therapeutic approaches aimed to selectively sensitize cancer cells to TRAIL. Recently, we identified ATM kinase as a novel modulator of the ability of chemotherapeutic agents to enhance TRAIL sensitivity. Here, we review the biological determinants of HCC responsiveness to TRAIL and provide an exhaustive and updated analysis of the molecular mechanisms exploited for combined therapy in this context. The role of ATM kinase as potential novel predictive biomarker for combined therapeutic approaches based on TRAIL and chemotherapeutic drugs will be closely discussed
An automatic deep learning approach for coronary artery calcium segmentation
Coronary artery calcium (CAC) is a significant marker of atherosclerosis and
cardiovascular events. In this work we present a system for the automatic
quantification of calcium score in ECG-triggered non-contrast enhanced cardiac
computed tomography (CT) images. The proposed system uses a supervised deep
learning algorithm, i.e. convolutional neural network (CNN) for the
segmentation and classification of candidate lesions as coronary or not,
previously extracted in the region of the heart using a cardiac atlas. We
trained our network with 45 CT volumes; 18 volumes were used to validate the
model and 56 to test it. Individual lesions were detected with a sensitivity of
91.24%, a specificity of 95.37% and a positive predicted value (PPV) of 90.5%;
comparing calcium score obtained by the system and calcium score manually
evaluated by an expert operator, a Pearson coefficient of 0.983 was obtained. A
high agreement (Cohen's k = 0.879) between manual and automatic risk prediction
was also observed. These results demonstrated that convolutional neural
networks can be effectively applied for the automatic segmentation and
classification of coronary calcifications
Comparison of energy consumption and costs of different HEVs and PHEVs in European and American context
This paper will analyse on the one hand the potential of Plug in Hybrid electric Vehicles to significantly reduce fuel consumption and displace it torward various primary energies thanks to the electricity sector. On the other hand the total cost of ownership of two different PHEV architectures will be compared to a conventional cehicle and a HEV without external charging
Complementarity relation for irreversible processes near steady states
A relation giving a minimum for the irreversible work in quasi-equilibrium processes was derived by Sekimoto et al. [K. Sekimoto, S. Sasa, J. Phys. Soc. Japan 66 (1997) 3326] in the framework of stochastic energetics. This relation can also be written as a type of “uncertainty principle” in such a way that the precise determination of the Helmholtz free energy through the observation of the work 〈W〉 requires an indefinitely large experimental time Δt. In the present article, we extend this relation to the case of quasi-steady processes by using the concept of non-equilibrium Helmholtz free energy. We give a formulation of the second law for these processes that extends that presented by Sekimoto [K. Sekimoto, Prog. Theoret. Phys. Suppl. No. 130 (1998) 17] by a term of the first order in the inverse of the experimental time. As an application of our results, two possible experimental situations are considered: stretching of a RNA molecule and the drag of a dipolar particle in the presence of a gradient of electric force.Fil: Santini, E. Comissão Nacional de Energia Nuclear; Brasil. Universidad Nacional de General Sarmiento. Instituto de Ciencias; Argentina. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Carusela, María Florencia. Universidad Nacional de General Sarmiento. Instituto de Ciencias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Izquierdo, E. D.. Universidad de Buenos Aires. Ciclo Básico Común; Argentina. Universidad de Buenos Aires. Facultad de Agronomia; Argentin
A Bell-Evans-Polanyi principle for molecular dynamics trajectories and its implications for global optimization
The Bell-Evans-Polanyi principle that is valid for a chemical reaction that
proceeds along the reaction coordinate over the transition state is extended to
molecular dynamics trajectories that in general do not cross the dividing
surface between the initial and the final local minima at the exact transition
state. Our molecular dynamics Bell-Evans-Polanyi principle states that low
energy molecular dynamics trajectories are more likely to lead into the basin
of attraction of a low energy local minimum than high energy trajectories. In
the context of global optimization schemes based on molecular dynamics our
molecular dynamics Bell-Evans-Polanyi principle implies that using low energy
trajectories one needs to visit a smaller number of distinguishable local
minima before finding the global minimum than when using high energy
trajectories
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