32,788 research outputs found
Magnetic and axial-vector transitions of the baryon antidecuplet
We report the recent results of the magnetic transitions and axial-vector
transitions of the baryon antidecuplet within the framework of the chiral
quark-soliton model. The dynamical model parameters are fixed by experimental
data for the magnetic moments of the baryon octet, for the hyperon semileptonic
decay constants, and for the singlet axial-vector constant. The transition
magnetic moments and are well reproduced
and other octet-decuplet and octet-antidecuplet transitions are predicted. In
particular, the present calculation of is found to be
below the upper bound that the SELEX collaboration measured very
recently. The results explains consistently the recent findings of a new
resonance from the GRAAL and Tohoku LNS group. We also obtain the transition
axial-vector constants for the from which the decay width of
the pentaquark baryon is determined as a function of the
pion-nucleon sigma term . We investigate the dependence of the
decay width of the on the , with the
varied within the range of the experimental uncertainty. We show that a small
decay width of the , i.e. MeV, is
compatible with the values of all known semileptonic decays with the generally
accepted value of for the proton.Comment: 8 pages, 5 figures, Talk given at the Yukawa International Seminar
(YKIS) 2006, "New frontiers in QCD", Kyoto, Japan, 20 Nov. - 8 Dec. 200
Finite temperature calculations for the bulk properties of strange star using a many-body approach
We have considered a hot strange star matter, just after the collapse of a
supernova, as a composition of strange, up and down quarks to calculate the
bulk properties of this system at finite temperature with the density dependent
bag constant. To parameterize the density dependent bag constant, we use our
results for the lowest order constrained variational (LOCV) calculations of
asymmetric nuclear matter. Our calculations for the structure properties of the
strange star at different temperatures indicate that its maximum mass decreases
by increasing the temperature. We have also compared our results with those of
a fixed value of the bag constant. It can be seen that the density dependent
bag constant leads to higher values of the maximum mass and radius for the
strange star.Comment: 21 pages, 2 tables, 12 figures Astrophys. (2011) accepte
Investigation on tensile properties of plain and nanoclay reinforced syntactic foams
Tensile properties of plain and nanoclay reinforced epoxy matrix syntactic foams with three different sizes of ceramic microballoons are investigated experimentally. Nine series of plain syntactic foams with 20, 40 and 60 volume fractions of microballoons are prepared and tested to study the volume fraction and size effects. Also nano syntactic foams specimens with six different weight fractions of nanoclay (0, 1, 2, 3, 5 & 7%) are tested and the effect of nanoclay content on the tensile properties is investigated. In addition to tensile tests, fracture modes of all syntactic foams are considered thoroughly by using scanning electron microscopy (SEM)
Mercury bioacumulation in muscle tissue of Carcarhinus dussumieri
The Persian Gulf and Sea of Oman boast a great diversity of cartilaginous fishes of which sharks with nearly 150 different species constitute a major part. Contamination of the fishes with various chemicals necessitates the meats produced being controlled from health and quality Points of view. In this study, mercury bioaccumulation in 29 specimens of Caracarhinus dussumieri caught in the coastal waters of Bandar-e- Lengeh was tested using flameless atomic absorption spectrophotometry. Results of the analyses on muscle tissue of the cited fish revealed the mercury level being lower than the standards (0.5 ppm) of the WHO at p‹.01 significant level. The length range was determined to be 68-90 cm in males and 67.5-88 cm in females. Mercury level in males (n=21) was assessed to be 0.21 ppm while in females (n=18) it was 0.19 ppm. Average mercury level was estimated as 0.19±0.023 ppm
Average stem biomass of Gundelia (Gundelia tournefortii L.) in Shanjan Rangelands, East Azerbaijan, Iran
The stem of plants can be used for animal grazing, wind erosion control, reduction of water flow, increase of evaporation and transpiration. In NW of Iran (East Azerbaijan Province), rangelands were utilized for animal grazing, but were later changed to agricultural land. Moreover, this vegetation has unsuitable vegetation coverage. We studied Gundelia tournefortii L. to determine its stem biomass characteristics. Data were collected with accidental sampling method (1*1 m) in this area. A total of 15 plots were collected and 75 samples were studied in this study. However, the minimum, maximum and mean stem biomass of this plant was 5.5, 22.6 and 10.5 g, respectively.Key word: Gundelia tournefortii L., Iran, rangeland, stem biomass
Fidelity for Multimode Thermal Squeezed States
In the theory of quantum transmission of information the concept of fidelity
plays a fundamental role. An important class of channels, which can be
experimentally realized in quantum optics, is that of Gaussian quantum
channels. In this work we present a general formula for fidelity in the case of
two arbitrary Gaussian states. From this formula one can get a previous result
(H. Scutaru, J. Phys. A: Mat. Gen {\bf 31}, 3659 (1998)), for the case of a
single mode; or, one can apply it to obtain a closed compact expression for
multimode thermal states.Comment: 5 pages, RevTex, submitted to Phys. Rev.
Computing with cells: membrane systems - some complexity issues.
Membrane computing is a branch of natural computing which abstracts computing models from the structure and the functioning of the living cell. The main ingredients of membrane systems, called P systems, are (i) the membrane structure, which consists of a hierarchical arrangements of membranes which delimit compartments where (ii) multisets of symbols, called objects, evolve according to (iii) sets of rules which are localised and associated with compartments. By using the rules in a nondeterministic/deterministic maximally parallel manner, transitions between the system configurations can be obtained. A sequence of transitions is a computation of how the system is evolving. Various ways of controlling the transfer of objects from one membrane to another and applying the rules, as well as possibilities to dissolve, divide or create membranes have been studied. Membrane systems have a great potential for implementing massively concurrent systems in an efficient way that would allow us to solve currently intractable problems once future biotechnology gives way to a practical bio-realization. In this paper we survey some interesting and fundamental complexity issues such as universality vs. nonuniversality, determinism vs. nondeterminism, membrane and alphabet size hierarchies, characterizations of context-sensitive languages and other language classes and various notions of parallelism
Do associated anomalies influence mortality in oesophageal atresia?
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