219 research outputs found
Meson decay in a corrected model
Extensively applied to both light and heavy meson decay and standing as one
of the most successful strong decay models is the model, in which
pair production is the dominant mechanism. The pair production can
be obtained from the non-relativistic limit of a microscopic interaction
Hamiltonian involving Dirac quark fields. The evaluation of the decay amplitude
can be performed by a diagrammatic technique for drawing quark lines. In this
paper we use an alternative approach which consists in a mapping technique, the
Fock-Tani formalism, in order to obtain an effective Hamiltonian starting from
same microscopic interaction. An additional effect is manifest in this
formalism associated to the extended nature of mesons: bound-state corrections.
A corrected is obtained and applied, as an example, to
and decays.Comment: 3 figures. To appear in Physical Review
Phase diagram of a random-anisotropy mixed-spin Ising model
We investigate the phase diagram of a mixed spin-1/2--spin-1 Ising system in
the presence of quenched disordered anisotropy. We carry out a mean-field and a
standard self-consistent Bethe--Peierls calculation. Depending on the amount of
disorder, there appear novel transition lines and multicritical points. Also,
we report some connections with a percolation problem and an exact result in
one dimension.Comment: 8 pages, 4 figures, accepted for publication in Physical Review
Tricritical behaviour in deterministic aperiodic Ising systems
We use a mixed-spin model, with aperiodic ferromagnetic exchange interactions
and crystalline fields, to investigate the effects of deterministic geometric
fluctuations on first-order transitions and tricritical phenomena. The
interactions and the crystal field parameters are distributed according to some
two-letter substitution rules. From a Migdal-Kadanoff real-space
renormalization-group calculation, which turns out to be exact on a suitable
hierarchical lattice, we show that the effects of aperiodicity are
qualitatively similar for tricritical and simple critical behaviour. In
particular, the fixed point associated with tricritical behaviour becomes fully
unstable beyond a certain threshold dimension (which depends on the
aperiodicity), and is replaced by a two-cycle that controls a weakened and
temperature-depressed tricritical singularity.Comment: Formatting improved. 7 pages, 2 figures (included). Journal reference
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Bovine breeds identification by trichological analysis.
This study aimed to identify bovine breeds through trichological morphology and morphometry and to validate this technique by comparing it with genetic characterization. Animals from Caracu, Curraleiro Pé-Duro, Nelore, and Bovino Pantaneiro breeds were studied. Morphological and morphometric analyses of the guard hairs were performed. The cuticular pattern was observed on the shaft and the medulla pattern on the shield of the samples. The cattle genetic characterization was accomplished using microsatellite markers. Statistical analyses were performed using R version 3.2.4 software. Pearson?s correlation test showed a high positive and significant correlation between the matrices generated by trichological and genetic analyses (r = 0,996 and p < 0.001). Trichological analysis is a useful method for cattle breed identification. Its potential for identifying other species of interest for animal production should be studied since it is a simple, low-cost, and non-invasive method
Intradermal Administration of Measles Vaccines1
The aim of the study reporfed here was to determine if bifurcated needles or multiple puncture cylinders would prove suitable for administration of measles vaccines. Children 9 to 11 months old in S#o Paula, Brazil, were assigned to receive either BikenCam 70 (5 000 TCl0,dO.S ml) or Edmonsfon-Zagreb (7 000 TCID,,IO.5 ml) measles vaccine intradermally with a bifurcated needle or a multiple puncture cylinder. These devices are usually used to administer smallpox or BCG vaccine. The volume of vaccine inoculated was approximately 0.003 ml. Measles 1gG antibodies were measured by enzyme-linked immunosorbent assay (ELlSA) at the time of vaccination and 8 weeks later. The study participants were examined 14 days after inoculation for possible adverse reactions. Overall, the children's average age was 9.5 f 0.66 months at vaccination. None of the 45 recipients of Biken-Cam vaccine responded serologically. The 49 Edmonston-Zagreb vaccine recipients immunized with fke mulfiple puncture cylinder had a somewhat higher serologic response rate (35%) and mean concentration of measles antibodies (323 mIUlm1) than those 51 who received the same vaccine administered with the bifurcated needle (26% and 291 mlUlm1, respectively). The rates of reported symptoms after vaccination did not difer significantly among the groups. Overall, the low serologic response rates following intradermal immunization with the devices tested in this study indicate that this route of administration is not suitable for routine administration of standard-titer vaccines
Suplementos energéticos para recria de novilhas de corte em pastagens anuais: desempenho animal.
RESUMO - Foi avaliado o desempenho de novilhas de corte dos três aos doze meses de idade, mantidas em pastagem cultivada logo após o desmame (experimento 1) e no primeiro inverno pós-desmame (experimento 2), com ou sem o fornecimento de suplementos energéticos. No período de 16/02 a 21/04/2001, as novilhas permaneceram em pastagem de milheto, exclusivamente sob pastejo (PAST1), suplementadas com grão de milho moído (PAST1/M) ou com polpa cítrica peletizada e moída (PAST1/P). No período de 13/07 a 09/10/2001, as novilhas foram mantidas em pastagem de aveia preta e azevém, sem suplementação (PAST2), suplementadas com grão de milho moído (PAST2/M) ou suplementadas com casca de soja (PAST2/C). Peso vivo (PV), ganho de peso diário médio (GDM) e escore de condição corporal (ECC) foram avaliados. No experimento 1, os animais suplementados apresentaram maior PV final, GDM e ECC que os não-suplementados, não diferindo entre si. No experimento 2, as novilhas suplementadas com casca de soja apresentaram maior GDM e PV final que as não-suplementadas, enquanto as suplementadas com grão de milho ficaram em posição intermediária. O maior ECC foi obtido pelos animais de PAST2/C, seguidos de PAST2/M e, por último, de PAST2. Novilhas de corte desmamadas aos 60- 90 dias devem ser suplementadas no período inicial pós-desmama, para que atinjam desenvolvimento satisfatório nesta fase do crescimento. Os subprodutos polpa cítrica e casca de soja podem substituir o grão de milho como suplementos energéticos para recria de novilhas de corte
EVALUATION OF PHYSIOLOGICAL RESPONSES IN DIFFERENT ANESTHETIC PROTOCOLS IN CAPYBARAS (HYDROCHOERUS HYDROCHAERIS).
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