245 research outputs found
Desempenho produtivo e características de carcaça de bovinos inteiros e castrados criados no sistema superprecoce.
Quarenta bovinos machos mestiços Simental-Nelore foram desmamados com idade entre 5 e 8 meses e daí confinados até o abate, objetivando testar duas condições sexuais (inteiros versus castrados no início do confinamento). Avaliaram-se o consumo voluntário de matéria seca por lote, o ganho de peso vivo, o ganho de peso relativo, a conversão alimentar por lote, o peso de carcaça quente, o rendimento de carcaça, o escore de conformação de carcaça, o escore de acabamento de gordura, a produção de gordura abdominal, a área de olho-de-lombo, o peso do quarto traseiro resfriado e a proporção deste sobre o peso da carcaça quente. Fomularam-se equações de regressão para estimar o peso de abate em função do peso inicial e da duração do confinamento. A castração mostrou-se não recomendável no sistema de produção de bovinos abatidos jovens, por resultar em animais de menor peso ao abate e em carcaças mais leves e de qualidade inferior. A utilização de animais inteiros melhorou o rendimento de carcaça e não prejudicou o grau de acabamento. Sob o manejo intensivo aqui estudado, a eficiência do crescimento mostrou-se fortemente dependente do peso dos bezerros à desmama no início do confinamento
Efeito da castração sobre a qualidade da carne de bovinos superprecoces.
Estudou-se o efeito da castração sobre a qualidade da carne de bovinos machos mestiços Nelore-Simental, abatidos com idade entre 11 e 14 meses. Na desmama, aos 5-8 meses, metade dos animais foi orquiectomizada e, após, todos foram confinados durante 158 ou 193 dias, até o abate. A dieta consumida consistiu de 88% de concentrados. Na carne crua dos dois grupos (inteiros e castrados) não houve variação estatística quanto a composição centesimal, ao pH e aos parâmetros de cor. O contra-filé assado dos castrados apresentou-se significativamente mais macio (4,78 contra 6,42 kgf), mais gorduroso (6,2 contra 4,4% na base úmida) e com maior perda por gotejamento de gordura durante a cocção (3,2 contra 2,2%), não diferindo dos inteiros quanto ao teor de colesterol, de matéria seca e perdas por evaporação e totais. As correlações testadas apresentaram baixos coeficientes, exceto entre pH e cor
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Reassessing the Role of Histaminergic Tuberomammillary Neurons in Arousal Control
The histaminergic neurons of the tuberomammillary nucleus (TMN(HDC)) of the posterior hypothalamus have long been implicated in promoting arousal. More recently, a role for GABAergic signaling by the TMN(HDC) neurons in arousal control has been proposed. Here, we investigated the effects of selective chronic disruption of GABA synthesis (via genetic deletion of the GABA synthesis enzyme, glutamic acid decarboxylase 67) or GABAergic transmission (via genetic deletion of the vesicular GABA transporter (VGAT)) in the TMN(HDC) neurons on sleep-wake in male mice. We also examined the effects of acute chemogenetic activation and optogenetic inhibition of TMN(HDC) neurons upon arousal in male mice. Unexpectedly, we found that neither disruption of GABA synthesis nor GABAergic transmission altered hourly sleep-wake quantities, perhaps because very few TMN(HDC) neurons coexpressed VGAT. Acute chemogenetic activation of TMN(HDC) neurons did not increase arousal levels above baseline but did enhance vigilance when the mice were exposed to a behavioral cage change challenge. Similarly, acute optogenetic inhibition had little effect upon baseline levels of arousal. In conclusion, we could not identify a role for GABA release by TMN(HDC) neurons in arousal control. Further, if TMN(HDC) neurons do release GABA, the mechanism by which they do so remains unclear. Our findings support the view that TMN(HDC) neurons may be important for enhancing arousal under certain conditions, such as exposure to a novel environment, but play only a minor role in behavioral and EEG arousal under baseline conditions.SIGNIFICANCE STATEMENT The histaminergic neurons of the tuberomammillary nucleus of the hypothalamus (TMN(HDC)) have long been thought to promote arousal. Additionally, TMN(HDC) neurons may counter-regulate the wake-promoting effects of histamine through co-release of the inhibitory neurotransmitter, GABA. Here, we show that impairing GABA signaling from TMN(HDC) neurons does not impact sleep-wake amounts and that few TMN(HDC) neurons contain the vesicular GABA transporter, which is presumably required to release GABA. We further show that acute activation or inhibition of TMN(HDC) neurons has limited effects upon baseline arousal levels and that activation enhances vigilance during a behavioral challenge. Counter to general belief, our findings support the view that TMN(HDC) neurons are neither necessary nor sufficient for the initiation and maintenance of arousal under baseline conditions
Superconductivity in the Hubbard model with correlated hopping: Slave-boson study
The slave boson mean-field studies of the ground state of the Hubbard model
with correlated hopping were performed. The approach qualitatively recovers the
exact results for the case of the hopping integral t equal to the correlated
hopping integral X. The phase diagram for the strongly correlated state with
only singly occupied sites, the weakly correlated state, where single and
double occupation is allowed, and for the superconducting state, was determined
for any values of X and any electron concentration n. At the half-filled band
(n=1) a direct transition from the superconductor to the Mott insulator was
found. In the region of strong correlations the superconducting solution is
stable for n close to 1, in contrast to the case of weak correlations, in which
superconductivity occurs at n close to 0 and n close to 2. We found also that
strong correlations change characteristics of the superconducting phase, e.g.
the gap in the excitation spectrum has a nonexponential dependence close to the
point of the phase transition.Comment: 13 pages, 24 Postscript figures (in 12 files
The 3-Band Hubbard-Model versus the 1-Band Model for the high-Tc Cuprates: Pairing Dynamics, Superconductivity and the Ground-State Phase Diagram
One central challenge in high- superconductivity (SC) is to derive a
detailed understanding for the specific role of the - and
- orbital degrees of freedom. In most theoretical studies an
effective one-band Hubbard (1BH) or t-J model has been used. Here, the physics
is that of doping into a Mott-insulator, whereas the actual high- cuprates
are doped charge-transfer insulators. To shed light on the related question,
where the material-dependent physics enters, we compare the competing magnetic
and superconducting phases in the ground state, the single- and two-particle
excitations and, in particular, the pairing interaction and its dynamics in the
three-band Hubbard (3BH) and 1BH-models. Using a cluster embedding scheme, i.e.
the variational cluster approach (VCA), we find which frequencies are relevant
for pairing in the two models as a function of interaction strength and doping:
in the 3BH-models the interaction in the low- to optimal-doping regime is
dominated by retarded pairing due to low-energy spin fluctuations with
surprisingly little influence of inter-band (p-d charge) fluctuations. On the
other hand, in the 1BH-model, in addition a part comes from "high-energy"
excited states (Hubbard band), which may be identified with a non-retarded
contribution. We find these differences between a charge-transfer and a Mott
insulator to be renormalized away for the ground-state phase diagram of the
3BH- and 1BH-models, which are in close overall agreement, i.e. are
"universal". On the other hand, we expect the differences - and thus, the
material dependence to show up in the "non-universal" finite-T phase diagram
(-values).Comment: 17 pages, 9 figure
Deficiências nutricionais no crescimento de Cordia verbenacea: altura e peso da matéria seca de planta.
Edição dos Resumos do 37º Congresso Brasileiro de Olericultura, Manaus, 1997. Resumo 017
Variable-range hopping in quasi-one-dimensional electron crystals
We study the effect of impurities on the ground state and the low-temperature
dc transport in a 1D chain and quasi-1D systems of many parallel chains. We
assume that strong interactions impose a short-range periodicicity of the
electron positions. The long-range order of such an electron crystal (or
equivalently, a charge-density wave) is destroyed by impurities. The 3D
array of chains behaves differently at large and at small impurity
concentrations . At large , impurities divide the chains into metallic
rods. The low-temperature conductivity is due to the variable-range hopping of
electrons between the rods. It obeys the Efros-Shklovskii (ES) law and
increases exponentially as decreases. When is small, the metallic-rod
picture of the ground state survives only in the form of rare clusters of
atypically short rods. They are the source of low-energy charge excitations. In
the bulk the charge excitations are gapped and the electron crystal is pinned
collectively. A strongly anisotropic screening of the Coulomb potential
produces an unconventional linear in energy Coulomb gap and a new law of the
variable-range hopping . remains
constant over a finite range of impurity concentrations. At smaller the
2/5-law is replaced by the Mott law, where the conductivity gets suppressed as
goes down. Thus, the overall dependence of on is nonmonotonic.
In 1D, the granular-rod picture and the ES apply at all . The conductivity
decreases exponentially with . Our theory provides a qualitative explanation
for the transport in organic charge-density wave compounds.Comment: 20 pages, 7 figures. (v1) The abstract is abridged to 24 lines. For
the full abstract, see the manuscript (v2) several changes in presentation
per referee's comments. No change in result
Análise molecular via ISSR de uma população nativa de Eplingiella fruticosa.
Edição Especial dos Anais do 3° Simpósio da Rede de Recursos Genéticos Vegetais do Nordeste, Aracaju, out. 2017
Epigenomic Profiling of Human CD4+ T Cells Supports a Linear Differentiation Model and Highlights Molecular Regulators of Memory Development
SummaryThe impact of epigenetics on the differentiation of memory T (Tmem) cells is poorly defined. We generated deep epigenomes comprising genome-wide profiles of DNA methylation, histone modifications, DNA accessibility, and coding and non-coding RNA expression in naive, central-, effector-, and terminally differentiated CD45RA+ CD4+ Tmem cells from blood and CD69+ Tmem cells from bone marrow (BM-Tmem). We observed a progressive and proliferation-associated global loss of DNA methylation in heterochromatic parts of the genome during Tmem cell differentiation. Furthermore, distinct gradually changing signatures in the epigenome and the transcriptome supported a linear model of memory development in circulating T cells, while tissue-resident BM-Tmem branched off with a unique epigenetic profile. Integrative analyses identified candidate master regulators of Tmem cell differentiation, including the transcription factor FOXP1. This study highlights the importance of epigenomic changes for Tmem cell biology and demonstrates the value of epigenetic data for the identification of lineage regulators
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