477 research outputs found
Correlations between isospin dynamics and Intermediate Mass Fragments emission time scales: a probe for the symmetry energy in asymmetric nuclear matter
We show new data from the Ni+Sn and Ni+Sn
reactions studied in direct kinematics with the CHIMERA detector at INFN-LNS
and compared with the reverse kinematics reactions at the same incident beam
energy (35 A MeV). Analyzing the data with the method of relative velocity
correlations, fragments coming from statistical decay of an excited
projectile-like (PLF) or target-like (TLF) fragments are discriminated from the
ones coming from dynamical emission in the early stages of the reaction. By
comparing data of the reverse kinematics experiment with a stochastic mean
field (SMF) + GEMINI calculations our results show that observables from neck
fragmentation mechanism add valuable constraints on the density dependence of
symmetry energy. An indication is found for a moderately stiff symmetry energy
potential term of EOS.Comment: Talk given by E. De Filippo at the 11th International Conference on
Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1,
2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference
Series (JPCS
Simultaneous learning of instantaneous and time-delayed genetic interactions using novel information theoretic scoring technique
BACKGROUND: Understanding gene interactions is a fundamental question in systems biology. Currently, modeling of gene regulations using the Bayesian Network (BN) formalism assumes that genes interact either instantaneously or with a certain amount of time delay. However in reality, biological regulations, both instantaneous and time-delayed, occur simultaneously. A framework that can detect and model both these two types of interactions simultaneously would represent gene regulatory networks more accurately. RESULTS: In this paper, we introduce a framework based on the Bayesian Network (BN) formalism that can represent both instantaneous and time-delayed interactions between genes simultaneously. A novel scoring metric having firm mathematical underpinnings is also proposed that, unlike other recent methods, can score both interactions concurrently and takes into account the reality that multiple regulators can regulate a gene jointly, rather than in an isolated pair-wise manner. Further, a gene regulatory network (GRN) inference method employing an evolutionary search that makes use of the framework and the scoring metric is also presented. CONCLUSION: By taking into consideration the biological fact that both instantaneous and time-delayed regulations can occur among genes, our approach models gene interactions with greater accuracy. The proposed framework is efficient and can be used to infer gene networks having multiple orders of instantaneous and time-delayed regulations simultaneously. Experiments are carried out using three different synthetic networks (with three different mechanisms for generating synthetic data) as well as real life networks of Saccharomyces cerevisiae, E. coli and cyanobacteria gene expression data. The results show the effectiveness of our approach
Interlayer Exchange Coupling Mediated by Valence Band Electrons
The interlayer exchange coupling mediated by valence band electrons in
all-semiconductor IV-VI magnetic/nonmagnetic superlattices is studied
theoretically. A 3D tight-binding model, accounting for the band and magnetic
structure of the constituent superlattice components is used to calculate the
spin-dependent part of the total electronic energy. The antiferromagnetic
coupling between ferromagnetic layers in EuS/PbS superlattices is obtained, in
agreement with the experimental evidences. The results obtained for the
coupling between antiferromagnetic layers in EuTe/PbTe superlattices are also
presented.Comment: 8 pages, 6 figures, to be submitted to Phys.Rev.
Projected Quasi-particle Perturbation theory
The BCS and/or HFB theories are extended by treating the effect of four
quasi-particle states perturbatively. The approach is tested on the pairing
hamiltonian, showing that it combines the advantage of standard perturbation
theory valid at low pairing strength and of non-perturbative approaches
breaking particle number valid at higher pairing strength. Including the
restoration of particle number, further improves the description of pairing
correlation. In the presented test, the agreement between the exact solution
and the combined perturbative + projection is almost perfect. The proposed
method scales friendly when the number of particles increases and provides a
simple alternative to other more complicated approaches
Vascular cognitive impairment linked to brain endothelium inflammation in early stages of heart failure in mice
Background
Although advanced heart failure (
HF
) is a clinically documented risk factor for vascular cognitive impairment, the occurrence and pathomechanisms of vascular cognitive impairment in early stages of
HF
are equivocal. Here, we characterize vascular cognitive impairment in the early stages of
HF
development and assess whether cerebral hypoperfusion or prothrombotic conditions are involved.
Methods and Results
Tgαq*44 mice with slowly developing isolated
HF
triggered by cardiomyocyte‐specific overexpression of G‐αq*44 protein were studied before the end‐stage
HF
, at the ages of 3, 6, and 10 months: before left ventricle dysfunction; at the stage of early left ventricle diastolic dysfunction (with preserved ejection fraction); and left ventricle diastolic/systolic dysfunction, respectively. In 6‐ to 10‐month‐old but not in 3‐month‐old Tgαq*44 mice, behavioral and cognitive impairment was identified with compromised blood‐brain barrier permeability, most significantly in brain cortex, that was associated with myelin sheet loss and changes in astrocytes and microglia. Brain endothelial cells displayed increased E‐selectin immunoreactivity, which was accompanied by increased amyloid‐β
1‐42
accumulation in piriform cortex and increased cortical oxidative stress (8‐
OH
dG immunoreactivity). Resting cerebral blood flow measured by magnetic resonance imaging in vivo was preserved, but ex vivo
NO
‐dependent cortical arteriole flow regulation was impaired. Platelet hyperreactivity was present in 3‐ to 10‐month‐old Tgαq*44 mice, but it was not associated with increased platelet‐dependent thrombogenicity.
Conclusions
We report for the first time that vascular cognitive impairment is already present in the early stage of
HF
development, even before left ventricle systolic dysfunction. The underlying pathomechanism, independent of brain hypoperfusion, involves preceding platelet hyperreactivity and brain endothelium inflammatory activation.
</jats:sec
Kondo effect in quantum dots coupled to ferromagnetic leads with noncollinear magnetizations: effects due to electron-phonon coupling
Spin-polarized transport through a quantum dot strongly coupled to
ferromagnetic electrodes with non-collinear magnetic moments is analyzed
theoretically in terms of the non-equilibrium Green function formalism.
Electrons in the dot are assumed to be coupled to a phonon bath. The influence
of electron-phonon coupling on tunnelling current, linear and nonlinear
conductance, and on tunnel magnetoresistance is studied in detail. Variation of
the main Kondo peaks and phonon satellites with the angle between magnetic
moments of the leads is analyzed.Comment: 19 pages, 6 figure
Upper limit on the photon fraction in highest-energy cosmic rays from AGASA data
A new method to derive an upper limit on photon primaries from small data
sets of air showers is developed which accounts for shower properties varying
with the primary energy and arrival direction. Applying this method to the
highest-energy showers recorded by the AGASA experiment, an upper limit on the
photon fraction of 51% (67%) at a confidence level of 90% (95%) for primary
energies above 1.25 * 10^20 eV is set. This new limit on the photon fraction
above the GZK cutoff energy constrains the Z-burst model of the origin of
highest-energy cosmic rays.Comment: 4 pages, 3 figures. Analysis extended to account for primary energy
resolution; conclusions unchanged. Accepted by Phys. Rev. Let
Competition between dynamical and sequential reaction channels in ^{197}Au+^{197}Au collisions at a bombarding energy of 23A MeV
Competition between the two reaction channels: sequential breakup and neck fragmentation has been studied in peripheral and semi-peripheral collisions of the 197 Au+ 197 Au system at bombarding energy of 23A MeV. It was found that the emission of heavy (A < 50) neck-originating fragments occurs in about 22% of ternary breakup events, making this reaction channel highly competitive with the sequential breakup of the projectile- or target-like fragment (78% of events)
Determination of impact parameters in aligned breakup of projectile-like fragments in 197Au + 197Au collisions at 23AMeV
Symmetric and asymmetric aligned breakup of projectile-like fragments in 197Au + 197Au collisions at 23AMeV was studied. Independently of the asymmetry, the reaction yields have been found peaked at a common, very
narrow range of impact parameters
- …