158 research outputs found
Comment on "Critique of q-entropy for thermal statistics" by M. Nauenberg
It was recently published by M. Nauenberg [1] a quite long list of objections
about the physical validity for thermal statistics of the theory sometimes
referred to in the literature as {\it nonextensive statistical mechanics}. This
generalization of Boltzmann-Gibbs (BG) statistical mechanics is based on the
following expression for the entropy:
S_q= k\frac{1- \sum_{i=1}^Wp_i^q}{q-1} (q \in {\cal R}; S_1=S_{BG} \equiv
-k\sum_{i=1}^W p_i \ln p_i) .
The author of [1] already presented orally the essence of his arguments in
1993 during a scientific meeting in Buenos Aires. I am replying now
simultaneously to the just cited paper, as well as to the 1993 objections
(essentially, the violation of "fundamental thermodynamic concepts", as stated
in the Abstract of [1]).Comment: 7 pages including 2 figures. This is a reply to M. Nauenberg, Phys.
Rev. E 67, 036114 (2003
Isolation of Salmonella enterica in opossum (Didelphis aurita and Didelphis albiventris) of the São Paulo State, Brazil
No Brasil, não há relato de estudos de Salmonella em gambás, sendo assim, este trabalho tem por objetivo determinar a frequência de isolamento de Salmonella enterica em gambás (D. aurita e D. albiventris) no Estado de São Paulo. No período de janeiro de 2005 a dezembro de 2006, foram necropsiados 106 D. aurita e 40 D. albiventris e colhidos fragmentos de intestinos delgado, grosso e suabe da cloaca. As amostras foram plaqueadas diretamente em ágar Mac Conkey, paralelamente suspendidas nos caldos Rappaport-Vassiliadis e Tetrationato e posteriormente plaqueados em ágar XLT4. As colônias sugestivas de Salmonella foram confirmadas através de provas bioquímicas e sorotipagem. Encontrou-se Salmonella enterica em 17,0% (18/106) dos D. aurita. Destes, 50% apresentaram positividade no intestino delgado (ID), 88,9% no intestino grosso (IG) e 66,7% na cloaca. Da espécie S. enterica, as subespécies encontradas foram: diarizonae (11,1%) houtenae e enterica (5,5% cada um); enquanto da subespécie S. enterica enterica os sorotipos foram Newport (83,3%), Typhimurium e Cerro (5,5% cada um). Nos D. albiventris, 17,5% (7/40) eram positivos, sendo que se encontraram 42,8% no ID, 85,7% no IG e 71,4% na cloaca. O sorotipo mais prevalente também foi Newport (71,4%), seguido por Typhimurium, Bareilly e Thompson (14,3% cada um). Através dos resultados obtidos neste estudo pode-se comprovar a presença de Salmonella enterica no trato intestinal de gambás no Brasil.In Brazil there is not report of Salmonella in opossum, so then, the objective of this study is to determine the isolation frequency of Salmonella enterica in opossum in São Paulo State, Brazil. From January 2005 to December 2006, 106 D. aurita and 40 D. albiventris were necropsied and samples from small and large intestine and cloacal swab were collected. These samples were submitted to direct plating in Mac Conkey agar and parallel suspension in Rappaport-Vassiliadis and Tetrationate broths with posterior streaking in XLT4 agar. The characterization of the isolates was done through biochemical tests and serotyping. Salmonella enterica was found in 17.0% (18/106) of the D. aurita; 50% presented the bacteria in the small intestine (SI), 88.9% in the large intestine (LI) and 66.7% in the cloaca. Of the S. enterica were found the subspecies: diarizonae (11.1%), enterica and houtenae (5.5% each); and the serotypes of the S. enterica enterica were Newport (83.3%), Typhimurium and Cerro (5.5% each). In the D. albiventris 17.5% (7/40) were positive; 42.8% in the SI, 85.7% in the LI and 71.4% in the cloaca. Newport (71.4%) was also the most frequent serotype and the second were Typhimurium, Bareilly and Thompson (14.3% each). The presence of Salmonella enterica in the intestines of opossums in Brazil was proved
Partonic flow and -meson production in Au+Au collisions at = 200 GeV
We present first measurements of the -meson elliptic flow
() and high statistics distributions for different
centralities from = 200 GeV Au+Au collisions at RHIC. In
minimum bias collisions the of the meson is consistent with the
trend observed for mesons. The ratio of the yields of the to those of
the as a function of transverse momentum is consistent with a model
based on the recombination of thermal quarks up to GeV/,
but disagrees at higher momenta. The nuclear modification factor () of
follows the trend observed in the mesons rather than in
baryons, supporting baryon-meson scaling. Since -mesons are
made via coalescence of seemingly thermalized quarks in central Au+Au
collisions, the observations imply hot and dense matter with partonic
collectivity has been formed at RHIC.Comment: 6 pages, 4 figures, submit to PR
Measurement of Transverse Single-Spin Asymmetries for Di-Jet Production in Proton-Proton Collisions at GeV
We report the first measurement of the opening angle distribution between
pairs of jets produced in high-energy collisions of transversely polarized
protons. The measurement probes (Sivers) correlations between the transverse
spin orientation of a proton and the transverse momentum directions of its
partons. With both beams polarized, the wide pseudorapidity () coverage for jets permits separation of Sivers functions for the valence
and sea regions. The resulting asymmetries are all consistent with zero and
considerably smaller than Sivers effects observed in semi-inclusive deep
inelastic scattering (SIDIS). We discuss theoretical attempts to reconcile the
new results with the sizable transverse spin effects seen in SIDIS and forward
hadron production in pp collisions.Comment: 6 pages total, 1 Latex file, 3 PS files with figure
- …