A Robertsonian translocation in swine

International audienc

High Order QED Corrections in Physics of Positronium

High-order perturbative corrections to positronium decays and hyperfine splitting are briefly reviewed. Theoretical predictions are compared to the most recent experimental data. Perspectives of future calculations are discussed.Comment: 8 pages, LaTeX, talk given at Workshop on Positronium Physics, ETH Honggerberg, Zurich, May 30-31, 2003, a misprint in Eq. (1) correcte

On the number of representations providing noiseless subsystems

This paper studies the combinatoric structure of the set of all representations, up to equivalence, of a finite-dimensional semisimple Lie algebra. This has intrinsic interest as a previously unsolved problem in representation theory, and also has applications to the understanding of quantum decoherence. We prove that for Hilbert spaces of sufficiently high dimension, decoherence-free subspaces exist for almost all representations of the error algebra. For decoherence-free subsystems, we plot the function $f_d(n)$ which is the fraction of all $d$-dimensional quantum systems which preserve $n$ bits of information through DF subsystems, and note that this function fits an inverse beta distribution. The mathematical tools which arise include techniques from classical number theory.Comment: 17 pp, 4 figs, accepted for Physical Review

Environmental impact of how carcasses from turkeys production industry are eliminated: a case study

The Americas is the largest turkey region in the world producing over 60% of the world total. After US, Brazil is the second largest producer in the region with more than 500,000 tons per year and, after European Union, the third producer in the world. For several reasons turkey production is prone to lost high number of effective, particularly the young poults are vulnerable to respiratory disease, outbreaks, including salmonellosis, which they become listless and, eventually, died. The production plants eliminate the turkey carcasses by composting them however when the compost facility is full, or many turkey poults died, the elimination can be done by burying them. The main aim of this work is study the practical conditions used by the production plants to landfill turkey carcasses. To perform the study a qualitative methodology was used combining the documentation analysis, including the legal framework and the companys records, and field work to make observations and interview the owner. The company chosen for this case study operated in Carlos Barbosa municipality (RS) with 5 collaborators and 12 years of uninterrupted activity, and capacity for 8,580 turkeys. In average the company lose by dead or illness around 1,500 turkeys per month and use 3 composting facilities each one with 2x1.5x1 m to disposal carcasses. Nevertheless, the company landfill nearby of its facilities dead turkeys without any control of aquifer or soil waterproof capacity. In conclusion, burying turkey carcasses needs an environmental impact assessment put in place and the incineration is not an economical viable treatment for this activity.info:eu-repo/semantics/publishedVersio

Constraints on Light Pseudoscalars Implied by Tests of the Gravitational Inverse-Square Law

The exchange of light pseudoscalars between fermions leads to a spin-independent potential in order g^4, where g is the Yukawa pseudoscalar-fermion coupling constant. This potential gives rise to detectable violations of both the weak equivalence principle (WEP) and the gravitational inverse-square law (ISL), even if g is quite small. We show that when previously derived WEP constraints are combined with those arisingfrom ISL tests, a direct experimental limit on the Yukawa coupling of light pseudoscalars to neutrons can be inferred for the first time (g_n^2/4pi < 1.6 \times 10^-7), along with a new (and significantly improved) limit on the coupling of light pseudoscalars to protons.Comment: 12 pages, Revtex, with 1 Postscript figure (submitted to Physical Review Letters

Modelling radiation-induced cell cycle delays

Ionizing radiation is known to delay the cell cycle progression. In particular after particle exposure significant delays have been observed and it has been shown that the extent of delay affects the expression of damage such as chromosome aberrations. Thus, to predict how cells respond to ionizing radiation and to derive reliable estimates of radiation risks, information about radiation-induced cell cycle perturbations is required. In the present study we describe and apply a method for retrieval of information about the time-course of all cell cycle phases from experimental data on the mitotic index only. We study the progression of mammalian cells through the cell cycle after exposure. The analysis reveals a prolonged block of damaged cells in the G2 phase. Furthermore, by performing an error analysis on simulated data valuable information for the design of experimental studies has been obtained. The analysis showed that the number of cells analyzed in an experimental sample should be at least 100 to obtain a relative error less than 20%.Comment: 19 pages, 11 figures, accepted for publication in Radiation and Environmental Biophysic