3,463 research outputs found
CP Violation in Vacuum Neutrino Oscillation Experiments
We discuss the use of the CP asymmetry parameter (Acp) as a possible observable of CP violation in the leptonic sector. In order to do this, we study for a wide range of values of L/E the behavior of this asymmetry for the corresponding maximal value of the CP violation factor allowed by all present experimental limits on neutrino oscillations in vacuum and the recent Super-Kamiokande atmospheric neutrino result. We work in the three neutrino flavor framework
3D-QSAR/CoMFA Models as a Tool for Biocatalysis and Protein Engineering
The x-ray structure of an enzyme is taken into account, when available, as the reference model to explain catalytic activity and selectivity. Unfortunately, in most of the cases the structure is available only as apostructure, i.e. without the substrate bound to
the active site, and it is strange to find many different enzyme-substrate complexes of a specific enzyme as crystals. Moreover this structure is not the "real" structure of the protein
during catalysis as the crystal is stationary.
In this paper we propose the use of CoMFA models to evaluate the differences betweenthe crystal and the real structure of the enzyme under reaction conditions.
In addition to the stationary nature of a crystal, the experimental limitations of crystallographic techniques to obtain crystals in a fast and reliable manner, give a chance to the creation of CoMFA models by evaluating the easy to obtain catalytic properties of enzyme variants to provide information about the structural changes produced
by the mutations. By means of the evaluation of different structures as substrates CoMFA models will not only provide information about the structure of the enzyme, but also about the flexibility and potential conformational changes of the substrate binding site
La caracterización molecular y ampelográfica de clones de "Albariño", "Savagnin Blanc" y "Caíño Blanco" (Vitis vinifera L.) demuestra que son cultivares diferentes
The grapevine cultivar "Albariño" is one of the oldest grown in the vine-growing areas of North-Western Spain and Northern Portugal. Since recognition of Origin Denomination status for the Rías Baixas region (the coast of Western Galicia, Spain) in 1987, the economic importance of this cultivar has increased, and its grapes are now among the most expensive in Spain. The area occupied by "Albariño" vines in this region is increasing every year, and the wines made from its grapes are gaining international recognition. These events, plus the fact that "Albariño" was little known outside its traditional growing area, have led to speculation about its origin and the existence of synonyms. Misnames of "Albariño" have included "Savagnin Blanc" and "Caíño Blanco". The present work compares "Albariño", "Savagnin Blanc" and "Caíño Blanco" ampelographically (i.e., it compares shoot, leaf, grape cluster, berry and seed characteristics) and molecularly using microsatellite markers. The results show that they are in fact three different cultivars providing a complete description. For "Caíño Blanco", there is little previously reported information.El "Albariño" es uno de los cultivares más antiguos de la zona vitícola del Noroeste de España y norte de Portugal. Desde la aprobación en el año 1987 de la Denominación de Origen Rías Baixas, este cultivar es el de mayor valor económico de esta zona vitícola, y su uva alcanza uno de los precios más elevados de España. Su superficie de cultivo, dentro de esta Denominación de Origen, se multiplica año tras año, y sus vinos adquieren fama internacional. Todo ello, unido a que era un cultivar poco conocido fuera de esta pequeña zona vitícola española, ha llevado a la aparición en los últimos años de diversas especulaciones sobre su origen, y a la atribución de diferentes sinonimias. Entre los nombres erróneamente atribuidos al "Albariño" se encuentran "Savagnin Blanc" y "Caíño Blanco". En el presente trabajo se hace un estudio comparativo de los tres cultivares a nivel ampelográfico (brote, hoja, racimo, baya, semilla) y a nivel molecular por medio de marcadores microsatélite. Los resultados demuestran que "Albariño", "Savagnin Blanc" y "Caíño Blanco" son cultivares distintos, proporcionando una completa descripción de cada uno. De uno de ellos, "Caíño Blanco", existe muy poca información previa
Seesaw tau lepton mass and calculable neutrino masses in a 3-3-1 model
In a version of the 3-3-1 model proposed by Duong and Ma the introduction of
the scalar sextet for giving mass to the charged leptons is avoided by adding a
singlet charged lepton. We show that in this case the lepton gains mass
through a seesaw--like mechanism. Besides we show how to generate neutrino
masses at the tree and at the 1-loop level with the respective
Maki-Nakagawa-Sakata leptonic mixing matrices.Comment: revtex, 5 pages and one eps figure. Published versio
Coulomb explosion sputtering of selectively oxidized Si
We have studied multiply charged Arq+ ion induced potential sputtering of a
unique system comprising of coexisting Silicon and Silicon oxide surfaces. Such
surfaces are produced by oblique angle oxygen ion bombardment on Si(100), where
ripple structures are formed and one side of each ripple gets more oxidized. It
is observed that higher the potential energy of Arq+ ion, higher the sputtering
yield of the non conducting (oxide) side of the ripple as compared to the
semiconducting side. The results are explained in terms of Coulomb explosion
model where potential sputtering depends on the conductivity of the ion impact
sites.Comment: 9 pages and 3 figure
Macro- and microscopic leaf characteristics of six grapevine genotypes (Vitis spp.) with different susceptibilities to grapevine downy mildew
This work reports the leaf morphology of six grapevine genotypes, five belonging to Vitis vinifera and one to Vitis riparia. Earlier studies on these genotypes showed different levels of susceptibility to grapevine downy mildew (Plasmopara viticola). The aim of this work was to detect differences between the leaf morphology of these cultivars at the macro- and microscopic levels, and to characterize morphological traits which could be associated with susceptibility and resistance to downy mildew. An ampelographic description of each genotype was used to develop a scheme illustrating the characteristic leaf morphology. The density and morphology of the trichomes and the stomatal index was assessed by means of microscopical techniques. Distinct macro and microscope differences among the genotypes were seen. No clear relation between ampelographic characteristics and susceptibility to downy mildew was observed. The two cultivars that in earlier studies were found to be the least susceptible to downy mildew were the most similar in terms of their spongy mesophyll. Both showed very little or no wax on the abaxial surface of their leaves.
Matter effects in neutrino visible decay at future long-baseline experiments
Neutrino visible decay in the presence of matter is re-evaluated. We study
these effects in two future long-baseline experiments where matter effects are
relevant: DUNE (1300 km) and a hypothetical beam aimed towards ANDES (7650 km).
We find that matter effects are negligible for the visible component of
neutrino decay at DUNE, being much more relevant at ANDES. We perform a
detailed simulation of DUNE, considering disappearance and
appearance channels, for both FHC and RHC modes. The sensitivity to the decay
constant can be as low as eV at 90% C.L.,
depending on the neutrino masses and type of coupling. We also show the impact
of neutrino decay in the determination of and ,
and find that the best-fit value of can move from a true value at
the lower octant towards the higher octant.Comment: 18 pages; v2: Minor changes, version accepted for publication in EPJ
Damping signatures in future neutrino oscillation experiments
We discuss the phenomenology of damping signatures in the neutrino
oscillation probabilities, where either the oscillating terms or the
probabilities can be damped. This approach is a possibility for tests of
non-oscillation effects in future neutrino oscillation experiments, where we
mainly focus on reactor and long-baseline experiments. We extensively motivate
different damping signatures due to small corrections by neutrino decoherence,
neutrino decay, oscillations into sterile neutrinos, or other mechanisms, and
classify these signatures according to their energy (spectral) dependencies. We
demonstrate, at the example of short baseline reactor experiments, that damping
can severely alter the interpretation of results, e.g., it could fake a value
of smaller than the one provided by Nature. In addition,
we demonstrate how a neutrino factory could constrain different damping models
with emphasis on how these different models could be distinguished, i.e., how
easily the actual non-oscillation effects could be identified. We find that the
damping models cluster in different categories, which can be much better
distinguished from each other than models within the same cluster.Comment: 33 pages, 5 figures, LaTeX. Final version published in JHE
Status of atmospheric neutrino(mu)<-->neutrino(tau) oscillations and decoherence after the first K2K spectral data
We review the status of nu_mu-->nu_tau flavor transitions of atmospheric
neutrinos in the 92 kton-year data sample collected in the first phase of the
Super-Kamiokande (SK) experiment, in combination with the recent spectral data
from the KEK-to-Kamioka (K2K) accelerator experiment (including 29 single-ring
muon events). We consider a theoretical framework which embeds flavor
oscillations plus hypothetical decoherence effects, and where both standard
oscillations and pure decoherence represent limiting cases. It is found that
standard oscillations provide the best description of the SK+K2K data, and that
the associated mass-mixing parameters are determined at 1 sigma (and d.o.f.=1)
as: Delta m^2=(2.6 +- 0.4)x10^{-3} eV^2 and sin^2(2theta)=1.00+0.00-0.05. As
compared with standard oscillations, the case of pure decoherence is
disfavored, although it cannot be ruled out yet. In the general case,
additional decoherence effects in the nu_mu-->nu_tau channel do not improve the
fit to the SK and K2K data, and upper bounds can be placed on the associated
decoherence parameter. Such indications, presently dominated by SK, could be
strengthened by further K2K data, provided that the current spectral features
are confirmed with higher statistics. A detailed description of the statistical
analysis of SK and K2K data is also given, using the so-called ``pull''
approach to systematic uncertainties.Comment: 18 pages (RevTeX) + 12 figures (PostScript
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