447 research outputs found
Recommended from our members
Measuring self-knowledge development : construction of a preliminary scoring manual.
First-principles dynamical CPA to finite-temperature magnetism of transition metals
We present here the first-principles dynamical CPA (coherent potential
approximation) combined with the tight-binding LMTO LDA+U method towards
quantitative calculations of the electronic structure and magnetism at finite
temperatures in transition metals and compounds. The theory takes into account
the single-site dynamical charge and spin fluctuations using the functional
integral technique as well as an effective medium. Numerical results for Fe,
Co, and Ni show that the theory explains quantitatively the high-temperature
properties such as the effective Bohr magneton numbers and the excitation
spectra in the paramagnetic state, and describes the Curie temperatures
semiquantitatively.Comment: ICM'09 Proceeding
Role Of Tamm-horsfall Protein In The Binding And In Vivo Phagocytosis Of Type 1 Fimbriated Escherichia Coli By Mouse Peritoneal Macrophages.
Tamm-Horsfall glycoprotein (THP) contains manno-oligosaccharides that are recognized by type 1 fimbriae (F1) of Escherichia coli. In the present study, we examined the in vivo phagocytic activity of mouse peritoneal macrophages after treatment of bacteria with THP. At low THP concentrations (12.5 microg/ml and 50 microg/ml) no significant difference was observed in the phagocytosis of E. coli F1+. However, at high THP concentrations (500 microg/ml and 1250 microg/ml) we obtained a reduction of bacterial phagocytosis by mouse peritoneal macrophages.34913-
Dynamical coherent-potential approximation approach to excitation spectra in 3d transition metals
First-principles dynamical CPA (Coherent-Potential Approximation) for
electron correlations has been developed further by taking into account
higher-order dynamical corrections with use of the asymptotic approximation.
The theory is applied to the investigations of a systematic change of
excitation spectra in transition metals from Sc to Cu at finite
temperatures. It is shown that the dynamical effects damp main peaks in the
densities of states (DOS) obtained by the local density approximation to the
density functional theory, reduce the band broadening due to thermal spin
fluctuations, create the Mott-Hubbard type bands in the case of fcc Mn and fcc
Fe, and create a small hump corresponding to the `6 eV' satellite in the case
of Co, Ni, and Cu. Calculated DOS explain the X-ray photoelectron spectroscopy
data as well as the bremsstrahlung isochromat spectroscopy data. Moreover, it
is found that screening effects on the exchange energy parameters are
significant for understanding the spectra in magnetic transition metals.Comment: To be published in Phys. Rev.
Field theoretical representation of the Hohenberg-Kohn free energy for fluids
To go beyond Gaussian approximation to the Hohenberg-Kohn free energy playing
the key role in the density functional theory (DFT), the density functional
\textit{integral} representation would be relevant, because field theoretical
approach to perturbative calculations becomes available. Then the present
letter first derives the associated Hamiltonian of density functional,
explicitly including logarithmic entropy term, from the grand partition
function expressed by configurational integrals. Moreover, two things are done
so that the efficiency of the obtained form may be revealed: to demonstrate
that this representation facilitates the field theoretical treatment of the
perturbative calculation, and further to compare our perturbative formulation
with that of the DFT.Comment: 5 pages, revtex, modified on 13 April 2000 [see eqs. (3), (6), and
(13)
Extracting Structural Information of a Heteropolymer from Force-Extension Curves
We present a theory for the reverse analysis on the sequence information of a
single H/P two-letter random hetero-polymer (RHP) from its force-extension(f-z)
curves during quasi static stretching. Upon stretching of a self-assembled RHP,
it undergoes several structural transitions. The typical elastic response of a
hetero-polymeric globule is a set of overlapping saw-tooth patterns. With
consideration of the height and the position of the overlapping saw-tooth
shape, we analyze the possibility of extracting the binding energies of the
internal domains and the corresponding block sizes of the contributing
conformations.Comment: 5 figures 7 page
Mechanical response of random heteropolymers
We present an analytical theory for heteropolymer deformation, as exemplified
experimentally by stretching of single protein molecules. Using a mean-field
replica theory, we determine phase diagrams for stress-induced unfolding of
typical random sequences. This transition is sharp in the limit of infinitely
long chain molecules. But for chain lengths relevant to biological
macromolecules, partially unfolded conformations prevail over an intermediate
range of stress. These necklace-like structures, comprised of alternating
compact and extended subunits, are stabilized by quenched variations in the
composition of finite chain segments. The most stable arrangements of these
subunits are largely determined by preferential extension of segments rich in
solvophilic monomers. This predicted significance of necklace structures
explains recent observations in protein stretching experiments. We examine the
statistical features of select sequences that give rise to mechanical strength
and may thus have guided the evolution of proteins that carry out mechanical
functions in living cells.Comment: 10 pages, 6 figure
Susceptibility or resilience? Prenatal stress predisposes male rats to social subordination, but facilitates adaptation to subordinate status
Mood disorders such as major depressive disorder (MDD) affect a significant proportion of the population. Although progress has been made in the development of therapeutics, a large number of individuals do not attain full remission of symptoms and adverse side effects affect treatment compliance for some. In order to develop new therapies, there is a push for new models that better reflect the multiple risk factors that likely contribute to the development of depressive illness. We hypothesized that early life stress would exacerbate the depressive-like phenotype that we have previously observed in socially subordinate (SUB) adult male rats in the visible burrow system (VBS), a semi-natural, ethologically relevant environment in which males in a colony form a dominance hierarchy. Dams were exposed to chronic variable stress (CVS) during the last week of gestation, resulting in a robust and non-habituating glucocorticoid response that did not alter maternal food intake, body weight or litter size and weight. As adults, one prenatal CVS (PCVS) and one non-stressed (NS) male were housed in the VBS with adult females. Although there were no overt differences between PCVS and NS male offspring prior to VBS housing, a greater percentage of PCVS males became SUB. However, the depressive-like phenotype of SUB males was not exacerbated in PCVS males; rather, they appeared to better cope with SUB status than NS SUB males. They had lower basal plasma corticosterone than NS SUB males at the end of VBS housing. In situ hybridization for CRH in the PVN and CeA did not reveal any prenatal treatment or status effects, while NPY expression was higher within the MeA of dominant and subordinate males exposed to the VBS in comparison with controls, but with no effect of prenatal treatment. These data suggest that prenatal chronic variable stress may confer resilience to offspring when exposed to social stress in adulthood
- …