558 research outputs found
Neurofly 2008 abstracts : the 12th European Drosophila neurobiology conference 6-10 September 2008 Wuerzburg, Germany
This volume consists of a collection of conference abstracts
The Two-Component Non-Perturbative Pomeron and the G-Universality
In this communication we present a generalization of the Donnachie-Landshoff
model inspired by the recent discovery of a 2-component Pomeron in LLA-QCD by
Bartels, Lipatov and Vacca. In particular, we explore a new property, not
present in the usual Regge theory - the G-Universality - which signifies the
independence of one of the Pomeron components on the nature of the initial and
final hadrons. The best description of all the forward hadron-hadron, gamma-
gamma and gamma-proton data is obtained when G-universailty is imposed.
Moreover, the maximal (ln)**2 behaviour of the hadron amplitude, first
established by Heisenberg, is clearly favoured by the data.Comment: 5 pages, 2 tables, talk at the International Workshop on Diffraction
in High-Energy Physics "Diffraction 2000", Cetraro, Italy, September 2-7,
200
Analytic Amplitudes for Hadronic Forward Scattering and the Heisenberg ln**2 Behaviour of Total Cross Section
The ln**2 behaviour of total cross sections, first obtained by Heisenberg 50
years ago, receives now increased interest both on phenomenological and
theoretical levels. We present a modification of the Heisenberg's model in
connection with the presence of glueballs and we show that it leads to a
realistic description of all existing hadron total cross-section data, in
agreement with the COMPETE analysis.Comment: 5 pages, 1 figure, 4 tables Invited talk at the QCD International
Conference QCD03, Montpellier, France, July 2-9, 200
Symmetry-preserving Loop Regularization and Renormalization of QFTs
A new symmetry-preserving loop regularization method proposed in \cite{ylw}
is further investigated. It is found that its prescription can be understood by
introducing a regulating distribution function to the proper-time formalism of
irreducible loop integrals. The method simulates in many interesting features
to the momentum cutoff, Pauli-Villars and dimensional regularization. The loop
regularization method is also simple and general for the practical calculations
to higher loop graphs and can be applied to both underlying and effective
quantum field theories including gauge, chiral, supersymmetric and
gravitational ones as the new method does not modify either the lagrangian
formalism or the space-time dimension of original theory. The appearance of
characteristic energy scale and sliding energy scale offers a
systematic way for studying the renormalization-group evolution of gauge
theories in the spirit of Wilson-Kadanoff and for exploring important effects
of higher dimensional interaction terms in the infrared regime.Comment: 13 pages, Revtex, extended modified version, more references adde
The Swiss Cheese Mutant Causes Glial Hyperwrapping and Brain Degeneration in Drosophila
Swiss cheese (sws) mutant flies develop normally during larval life but show age-dependent neurodegeneration in the pupa and adult and have reduced life span. In late pupae, glial processes form abnormal, multilayered wrappings around neurons and axons. Degeneration first becomes evident in young flies as apoptosis in single scattered cells in the CNS, but later it becomes severe and widespread. In the adult, the number of glial wrappings increases with age. The sws gene is expressed in neurons in the brain cortex. The conceptual 1425 amino acid protein shows two domains with homology to the regulatory subunits of protein kinase A and to conceptual proteins of yet unknown function in yeast, worm, and human. Sequencing of two sws alleles shows amino acid substitutions in these two conserved domains. It is suggested that the novel SWS protein plays a role in a signaling mechanism between neurons and glia that regulates glial wrapping during development of the adult brain
The swiss cheese mutant causes glial hyperwrapping and brain degeneration in Drosophila
Swiss cheese (sws) mutant flies develop normally during larval life but show age-dependent neurodegeneration in the pupa and adult and have reduced life span. In late pupae, glial processes form abnormal, multilayered wrappings around neurons and axons. Degeneration first becomes evident in young flies as apoptosis in single scattered cells in the CNS, but later it becomes severe and widespread. In the adult, the number of glial wrappings increases with age. The sws gene is expressed in neurons in the brain cortex. The conceptual 1425 amino acid protein shows two domains with homology to the regulatory subunits of protein kinase A and to conceptual proteins of yet unknown function in yeast, worm, and human. Sequencing of two sws alleles shows amino acid substitutions in these two conserved domains. It is suggested that the novel SWS protein plays a role in a signaling mechanism between neurons and glia that regulates glial wrapping during development of the adult brain
Anisotropy effects in a mixed quantum-classical Heisenberg model in two dimensions
We analyse a specific two dimensional mixed spin Heisenberg model with
exchange anisotropy, by means of high temperature expansions and Monte Carlo
simulations. The goal is to describe the magnetic properties of the compound
(NBu_{4})_{2}Mn_{2}[Cu(opba)]_{3}\cdot 6DMSO\cdot H_{2}O which exhibits a
ferromagnetic transition at . Extrapolating our analysis on the
basis of renormalisation group arguments, we find that this transition may
result from a very weak anisotropy effect.Comment: 8 pages, 10 Postscript figure
Control of Directed Cell Migration In Vivo by Membrane-to-Cortex Attachment
Analysis of cell migration in vivo combined with biophysical measurements reveals how membrane-to-cortex attachment fine-tunes the type of protrusions formed by cells and, as a consequence, controls directed migration during zebrafish gastrulation
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