47,279 research outputs found
Description of Four-Body Breakup Reaction with the Method of Continuum-Discretized Coupled-Channels
We present a method for smoothing discrete breakup -matrix elements
calculated by the method of continuum-discretized coupled-channels (CDCC). This
smoothing method makes it possible to apply CDCC to four-body breakup
reactions. The reliability of the smoothing method is confirmed for two cases,
Ni(, ) at 80 MeV and the transition of He. We apply
CDCC with the smoothing method to He breakup reaction at 22.5 MeV.
Multi-step breakup processes are found to be important.Comment: 19 pages, 7 figures, published in Progress of Theoretical Physic
Antigen-specific electrophoretic cell separation for immunological investigations
Preincubation of human blood lymphocytes with cell surface antigen specific antibodies under non-capping conditions reduces the electrophoretic mobility of the corresponding lymphocyte subpopulation. Antigen-positive and antigen-negative cells can be separated by free flow electrophoresis with high yield, purity and viability. The use of fluorescence-labelled second antibodies augments the induced decrease in net surface charge density, and allows rapid detection of antigen-positive cells in the fractions of electrophoresis. Carrier-free cell electrophoresis of human peripheral blood lymphocytes after reaction with anti-IgM-antibody or the monoclonal antibodies OKT4 or OKT8, and sandwich staining with tetrarhodamine isothiocyanate-labelled anti-IgG resulted in the large-scale separation of high pure human B and T lymphocyte subpopulations. Their functional integrity was shown in assays of lymphocyte transformation and of antigen-specific induction and regulation of antibody synthesis in vitro. These separate lymphocyte subpopulations are useful tools for immunological investigations. While, for instance, the effects of drugs on human lymphocytes are obscured by coincident changes in cell composition of the peripheral blood tested that do not by themselves reflect whole body immunocompetence, the cell separation and in vitro assays at a defined cell number and cell composition allow the recording of quantitative changes in the function of different cell subpopulations. We studied the influence of the anesthetic thiopental on separated human lymphocyte subsets. In both polyclonal lectin stimulation and in vitro antibody production, thiopental exhibited a noncytotoxic suppression of lymphocyte functions. B-Cells, T-helper and T-suppressor cells were equally affected and showed the same dose response.(ABSTRACT TRUNCATED AT 250 WORDS
Self-organization of heterogeneous topology and symmetry breaking in networks with adaptive thresholds and rewiring
We study an evolutionary algorithm that locally adapts thresholds and wiring
in Random Threshold Networks, based on measurements of a dynamical order
parameter. A control parameter determines the probability of threshold
adaptations vs. link rewiring. For any , we find spontaneous symmetry
breaking into a new class of self-organized networks, characterized by a much
higher average connectivity than networks without threshold
adaptation (). While and evolved out-degree distributions
are independent from for , in-degree distributions become broader
when , approaching a power-law. In this limit, time scale separation
between threshold adaptions and rewiring also leads to strong correlations
between thresholds and in-degree. Finally, evidence is presented that networks
converge to self-organized criticality for large .Comment: 4 pages revtex, 6 figure
Constraint on the Low Energy Constants of Wilson Chiral Perturbation Theory
Wilson chiral perturbation theory (WChPT) is the effective field theory
describing the long- distance properties of lattice QCD with Wilson or
twisted-mass fermions. We consider here WChPT for the theory with two light
flavors of Wilson fermions or a single light twisted-mass fermion.
Discretization errors introduce three low energy constants (LECs) into
partially quenched WChPT at O(a^2), conventionally called W'_6, W'_7 and W'_8 .
The phase structure of the theory at non-zero a depends on the sign of the
combination 2W'_6 + W'_8, while the spectrum of the lattice Hermitian
Wilson-Dirac operator depends on all three constants. It has been argued, based
on the positivity of partition functions of fixed topological charge, and on
the convergence of graded group integrals that arise in the epsilon-regime of
ChPT, that there is a constraint on the LECs arising from the underlying
lattice theory. In particular, for W'_6 = W'_7 = 0, the constraint found is
W'_8 \le 0. Here we provide an alternative line of argument, based on mass
inequalities for the underlying partially quenched theory. We find that W'_8
\le 0, irrespective of the values of W'_6 and W'_7. Our constraint implies that
2W'_6 > |W'_8| if the phase diagram is to be described by the first-order
scenario, as recent simulations suggest is the case for some choices of action.Comment: 10 pages, no figure
Lattice model for cold and warm swelling of polymers in water
We define a lattice model for the interaction of a polymer with water. We
solve the model in a suitable approximation. In the case of a non-polar
homopolymer, for reasonable values of the parameters, the polymer is found in a
non-compact conformation at low temperature; as the temperature grows, there is
a sharp transition towards a compact state, then, at higher temperatures, the
polymer swells again. This behaviour closely reminds that of proteins, that are
unfolded at both low and high temperatures.Comment: REVTeX, 5 pages, 2 EPS figure
Evidence of vorticity and shear at large angular scales in the WMAP data: a violation of cosmological isotropy?
Motivated by the large-scale asymmetry observed in the cosmic microwave
background sky, we consider a specific class of anisotropic cosmological models
-- Bianchi type VII_h -- and compare them to the WMAP first-year data on large
angular scales. Remarkably, we find evidence of a correlation which is ruled
out as a chance alignment at the 3sigma level. The best fit Bianchi model
corresponds to x=0.55, Omega_0=0.5, a rotation axis in the direction
(l,b)=(222degr,-62degr), shear (sigma/H)_0=2.4e-10 and a right--handed
vorticity (omega/H)_0=6.1e-10. Correcting for this component greatly reduces
the significance of the large-scale power asymmetry, resolves several anomalies
detected on large angular scales (ie. the low quadrupole amplitude and
quadrupole/octopole planarity and alignment), and can account for a
non--Gaussian "cold spot" on the sky. Despite the apparent inconsistency with
the best-fit parameters required in inflationary models to account for the
acoustic peaks, we consider the results sufficiently provocative to merit
further consideration.Comment: 4 pages, 3 figures; emulateapj.cls; ApJL accepted version plus fixed
error in vorticity calculation (sqrt(2) off in Table 1, abstract, and
conclusions); basic conclusions unchange
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