共查询到20条相似文献,搜索用时 15 毫秒
1.
Julia Lindberg Peter Saetre Seiji Nishino Emmanuel Mignot Elena Jazin 《BMC neuroscience》2007,8(1):34
Background
Narcolepsy causes dramatic behavioral alterations in both humans and dogs, with excessive sleepiness and cataplexy triggered by emotional stimuli. Deficiencies in the hypocretin system are well established as the origin of the condition; both from studies in humans who lack the hypocretin ligand (HCRT) and in dogs with a mutation in hypocretin receptor 2 (HCRTR2). However, little is known about molecular alterations downstream of the hypocretin signals. 相似文献2.
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A. Chudaykin 《Physics of Atomic Nuclei》2016,79(11-12):1477-1480
We confront different up to date cosmological data with different gravity models of the Universe with one additional massive sterile neutrino [1]. 相似文献
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M. Davier S. Descotes-Genon A. Höcker B. Malaescu Z. Zhang 《The European Physical Journal C - Particles and Fields》2008,56(3):305-322
We revisit the determination of α
S
(m
τ
2) using a fit to inclusive τ hadronic spectral moments in light of (1) the recent calculation of the fourth-order perturbative coefficient K
4 in the expansion of the Adler function, (2) new precision measurements from BABAR of e+e− annihilation cross sections, which decrease the uncertainty in the separation of vector and axial-vector spectral functions,
and (3) improved results from BABAR and Belle on τ branching fractions involving kaons. We estimate that the fourth-order perturbative prediction reduces the theoretical uncertainty,
introduced by the truncation of the series, by 20% with respect to earlier determinations. We discuss to some detail the perturbative
prediction of two different methods: fixed-order perturbation theory (FOPT) and contour-improved perturbative theory (CIPT).
The corresponding theoretical uncertainties are studied at the τ and Z mass scales. The CIPT method is found to be more stable with respect to the missing higher order contributions and to renormalization
scale variations. It is also shown that FOPT suffers from convergence problems along the complex integration contour. Nonperturbative
contributions extracted from the most inclusive fit are small, in agreement with earlier determinations. Systematic effects
from quark-hadron duality violation are estimated with simple models and found to be within the quoted systematic errors.
The fit based on CIPT gives α
S
(m
τ
2)=0.344±0.005±0.007, where the first error is experimental and the second theoretical. After evolution to M
Z
we obtain α
S
(M
Z
2)=0.1212±0.0005±0.0008±0.0005, where the errors are respectively experimental, theoretical and due to the evolution. The result
is in agreement with the corresponding N3LO value derived from essentially the Z width in the global electroweak fit. The α
S
(M
Z
2) determination from τ decays is the most precise one to date. 相似文献
10.
Through phase transformation kinetic analysis and experimental observation, the δ/γ transformation occurring in the non-equilibrium peritectic Fe-4.33at.%Ni alloys was systematically investigated. According to JMA solid-state transformation kinetic theory, the Time-Temperature-Transformation (TTT) curves of the δ/γ transformation in peritectic Fe-Ni alloy were calculated. On this basis, the physical correlation between the δ/γ transformation and the initial undercooling of melt (△T) was elucidated. The results indicate that the change of △T can alter not only the overall δ/γ transformation pathways but also the transformation fraction with respect to each transformation mechanism. 相似文献
11.
Decay properties of <Emphasis Type="Italic">N</Emphasis>∼<Emphasis Type="Italic">Z</Emphasis> nuclei
E. Roeckl 《Physics of Atomic Nuclei》2002,65(4):689-696
By using heavy-ion induced fusion-evaporation reactions at the on-line mass separator of GSI, the decay properties of neutron-deficient isotopes between 56Ni and 100Sn were investigated. The experimental results will be presented and discussed in comparison with model predictions. 相似文献
12.
Ctirad Klimčík 《International Journal of Theoretical Physics》2007,46(10):2443-2463
We show that D-branes in the Euclidean AdS
3 can be naturally associated to the maximally isotropic subgroups of the Lu–Weinstein double of SU(2). This picture makes very transparent the residual loop group symmetry of the D-brane configurations and gives also immediately the D-branes shapes and the σ-model boundary conditions in the de Sitter T-dual of the SL(2,C)/SU(2) WZW model. 相似文献
13.
A. A. Starobinsky 《JETP Letters》2007,86(3):157-163
For higher-derivative f(R) gravity, where R is the Ricci scalar, a class of models is proposed, which produce viable cosmology different from the ACDM at recent times
and satisfy cosmological, Solar System, and laboratory tests. These models have both flat and de Sitter spacetimes as particular
solutions in the absence of matter. Thus, a cosmological constant is zero in a flat spacetime, but appears effectively in
a curved one for sufficiently large R. A “smoking gun” for these models would be a small discrepancy in the values of the slope of the primordial perturbation
power spectrum determined from galaxy surveys and CMB fluctuations. On the other hand, a new problem for dark energy models
based on f(R) gravity is pointed out, which is connected with the possible overproduction of new massive scalar particles (scalarons)
arising in this theory in the very early Universe.
The text was submitted by the author in English. 相似文献
14.
Though the predictions of the standard model (SM) are in excellent agreement with experiments, there are still several theoretical
problems associated with the Higgs sector of the SM, where it is widely believed that some new physics will take over at the
TeV scale. One beyond the SM theory which resolves these problems is the Little Higgs (LH) model. In this work we have investigated
the effects of the LH model on γγ → γγ scattering [1].
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A γ-rigid version (with γ = 0) of the X(5) critical point symmetry is constructed. The model, to be called X(3) since it is proved to contain three degrees of freedom, utilizes an infinite well potential, is based on exact separation
of variables, and leads to parameter-free (up to overall scale factors) predictions for spectra and B(E2) transition rates which are in good agreement with existing experimental data for 172Os and 186Pt. An unexpected similarity of the β
1 bands of the X(5) nuclei 150Nd, 152Sm, 154Gd, and 156Dy to the X(3) predictions is observed.
The text was submitted by the authors in English. 相似文献
18.
The properties of polycrystalline CdTe with a grain size of 5–30 μm have been investigated using the microphotoluminescence
methods of spectral analysis and topography. This material has been prepared by direct synthesis in a vapor flow of components
at a low temperature. The dominance of the Y and Z bands in the spectra reflects a nonequilibrium character of the crystallization processes. The superlinear dependences of
the luminescence intensity on the level of the band-to-band excitation indicate the exciton nature of the corresponding transitions.
The activation energies for temperature quenching of luminescence in the temperature range T = 100–150 K are found to be 120 meV for the Y luminescence and 180 meV for the Z luminescence, which correspond to the dissociation of excitons bound to defects with the transition of charge carriers to
the conduction and valence bands. The monochromatic topography data indicate that Y and Z defects have different material bases. 相似文献
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S. P. Baranov 《JETP Letters》2008,88(8):471-474
In the framework of k
t
-factorization approach, the process of inclusive photoproduction of J/Ψ mesons at HERA conditions is considered. The spin density matrix elements are calculated, and the predictions are compared
with recent experimental data.
The article is published in the original. 相似文献