Carbon Nanotubes Band Assignation, Topology, Bloch States and Selection Rules

Various properties of the energy band structures (electronic, phonon, etc.), including systematic band degeneracy, sticking and extremes, following from the full line group symmetry of the single-wall carbon nanotubes are established. The complete set of quantum numbers consists of quasi momenta (angular and linear or helical) and parities with respect to the z-reversal symmetries and, for achiral tubes, the vertical plane. The assignation of the electronic bands is performed, and the generalized Bloch symmetry adapted eigen functions are derived. The most important physical tensors are characterized by the same set of quantum numbers. All this enables application of the presented exhaustive selection rules. The results are discussed by some examples, e.g. allowed interband transitions, conductivity, Raman tensor, etc.Comment: 11 pages, 2 figures, 2 tables; pdf available from: http://www.ff.bg.ac.yu/qmf/qsg_e.ht

Nonleptonic Ω−\Omega^{-} decays and the Skyrme model

Nonleptonic $\Omega^{-}$ decay branching ratios are estimated by means of the QCD enhanced effective weak Hamiltonian supplemented by the SU(3) Skyrme model used to estimate the nonperturbative matrix elements. The model has only one free parameter, namely the Skyrme charge $e$, which is fixed through the experimental values of the octet-decuplet mass splitting $\Delta$ and the axial coupling constant $g_{A}$. The whole scheme is equivalent to that which works well for the nonleptonic hyperon decays. The ratios of calculated amplitudes are in agreement with experiment. However, the absolute values are about twice too large if short-distance corrections and only ground intermediate states are included.Comment: 4 pages, 1 figure, 1 table, version to appear in Phys.Rev.

Magnetic Pinning of Vortices in a Superconducting Film: The (anti)vortex-magnetic dipole interaction energy in the London approximation

The interaction between a superconducting vortex or antivortex in a superconducting film and a magnetic dipole with in- or out-of-plane magnetization is investigated within the London approximation. The dependence of the interaction energy on the dipole-vortex distance and the film thickness is studied and analytical results are obtained in limiting cases. We show how the short range interaction with the magnetic dipole makes the co-existence of vortices and antivortices possible. Different configurations with vortices and antivortices are investigated.Comment: 12 pages, 12 figures. Submitted to Phys. Rev.

Capture into Rydberg states and momentum distributions of ionized electrons

The yield of neutral excited atoms and low-energy photoelectrons generated by the electron dynamics in the combined Coulomb and laser field after tunneling is investigated. We present results of Monte-Carlo simulations built on the two-step semiclassical model, as well as analytic estimates and scaling relations for the population trapping into the Rydberg states. It is shown that mainly those electrons are captured into bound states of the neutral atom that due to their initial conditions (i) have moderate drift momentum imparted by the laser field and (ii) avoid strong interaction ("hard" collision) with the ion. In addition, it is demonstrated that the channel of capture, when accounted for in semiclassical calculations, has a pronounced effect on the momentum distribution of electrons with small positive energy. For the parameters that we investigated its presence leads to a dip at zero momentum in the longitudinal momentum distribution of the ionized electrons.Comment: 9 pages, 8 figures in one zip-archiv

Two-band superconductors: Extended Ginzburg-Landau formalism by a systematic expansion in small deviation from the critical temperature

We derive the extended Ginzburg-Landau (GL) formalism for a clean s-wave two-band superconductor by employing a systematic expansion of the free-energy functional and the corresponding matrix gap equation in powers of the small deviation from the critical temperature tau = 1-T/T_c. The two lowest orders of this expansion produce the equation for T_c and the GL theory. It is shown that in agreement with previous studies, the two-band GL theory maps onto the single-band GL model and thus fails to describe the difference in the spatial profiles of the two band condensates. We prove that except for some very special cases, this difference appears already in the leading correction to the GL theory, which constitutes the extended GL formalism. We derive linear differential equations that determine the leading corrections to the band order parameters and magnetic field, discuss the validity of these equations, and consider examples of an important interplay between the band condensates. Finally, we present numerical results for the thermodynamic critical magnetic field and temperature-dependent band gaps (at zero field), which are in a very good agreement with those obtained from the full BCS approach in a wide temperature range. To this end, we emphasize the advantages of our extended GL theory in comparison with the often used two-component GL-like model based on an unreconstructed two-band generalization of the Gor'kov derivation

Extended Ginzburg-Landau formalism: systematic expansion in small deviation from the critical temperature

Based on the Gor'kov formalism for a clean s-wave superconductor, we develop an extended version of the single-band Ginzburg-Landau (GL) theory by means of a systematic expansion in the deviation from the critical temperature T_c, i.e., tau=1-T/T_c. We calculate different contributions to the order parameter and the magnetic field: the leading contributions (~ tau^1/2 in the order parameter and ~ tau in the magnetic field) are controlled by the standard Ginzburg-Landau (GL) theory, while the next-to-leading terms (~ tau^3/2 in the gap and ~ tau^2 in the magnetic field) constitute the extended GL (EGL) approach. We derive the free-energy functional for the extended formalism and the corresponding expression for the current density. To illustrate the usefulness of our formalism, we calculate, in a semi-analytical form, the temperature-dependent correction to the GL parameter at which the surface energy becomes zero, and analytically, the temperature dependence of the thermodynamic critical field. We demonstrate that the EGL formalism is not just a mathematical extension to the theory - variations of both the gap and the thermodynamic critical field with temperature calculated within the EGL theory are found in very good agreement with the full BCS results down to low temperatures, which dramatically improves the applicability of the formalism compared to its standard predecessor

Beam test evaluation of electromagnetic calorimeter modules made from proton-damaged PbWO4 crystals

The performance of electromagnetic calorimeter modules made of proton-irradiated PbWO4 crystals has been studied in beam tests. The modules, similar to those used in the Endcaps of the CMS electromagnetic calorimeter (ECAL), were formed from 5x5 matrices of PbWO4 crystals, which had previously been exposed to 24 GeV protons up to integrated fluences between 2.1 x 10(13) and 1.3 x 10(14) cm(-2). These correspond to the predicted charged-hadron fluences in the ECAL Endcaps at pseudorapidity eta = 2.6 after about 500 fb(-1) and 3000 fb(-1) respectively, corresponding to the end of the LHC and High Luminosity LHC operation periods. The irradiated crystals have a lower light transmission for wavelengths corresponding to the scintillation light, and a correspondingly reduced light output. A comparison with four crystals irradiated in situ in CMS showed no significant rate dependence of hadron-induced damage. A degradation of the energy resolution and a non-linear response to electron showers are observed in damaged crystals. Direct measurements of the light output from the crystals show the amplitude decreasing and pulse becoming faster as the fluence increases. The latter is interpreted, through comparison with simulation, as a side-effect of the degradation in light transmission. The experimental results obtained can be used to estimate the long term performance of the CMS ECAL

DIFFERENT SOURCES AND LEVELS OF VEGETABLE OILS IN BROILER CHICKEN NUTRITION

Abstract: The aim of this study was to investigate the effects of soybean, flax and rapeseed oil on productive performance and carcass quality of broilers chickens. At the beginning of the experiment six groups of 40 one day-old chicks, hybrid line Cobb 500 was formed, with five replications. For nutrition two feed mixtures were used. During the first two weeks, in preparation period, chickens were fed with starter mixture, and then with grower mixture until the end of the experiment. Control group was fed with mixture of standard composition and quality based on corn and soybean meal with the addition of 4% and 8% soybean oil, while the experimental group included 4% and 8% flaxseed oil and 4% and 8% rapeseed oil. The experiment lasted 35 days. During the experimental period, chickens were fed and watered ad libitum and microclimatic conditions were constantly monitored. Control of body weight and feed consumption was carried out every seven days. At the end of the experiment 10 chickens from each group were sacrificed for the purpose of testing the carcass quality. Upon completion of the experiment, control group achieved weight of 2122g and 2053g, and the experimental group with flax oil 2164g and 2094g, and the group with rapeseed oil weighs of 2121g and 2081g. Chickens on treatment with 4% flax oil in the diet achieved significantly higher body mass (P<0.05) at the end of the experiment compared with the groups who were on treatment with 8% rapeseed and soybean oil. Soybean oil at a rate of 4% showed significantly (P<0.05) increased final body weight compared to body mass of chicks in a group with the addition of 8% soybean oil. Feed conversion ratio was lowest in the group with the addition of 4% flax oil and rapeseed oil, and the highest in the group with the addition of 8% flax oil. The differences found in the carcass quality between the control and experimental groups were not statistically significant (P>0.05). The largest amount of abdominal fat (18.9 g) was in the group with the addition of 4% rapeseed oil and V.Ž. Stanaćev et al. 322 lowest in the group with the addition of 8% soybean oil (12.6 g). Based on these results it can be concluded that the addition of 4% oil showed better productive results, but had no effect on carcass quality of chickens

Effects of dietary soybean, flaxseed and rapeseed oil addition on broilers meat quality

The aim of this paper is was to investigate the effects of soybean oil, flax and rapeseed oil on the body weight, fatty acid composition of lipids and sensory characteristics of chicken breast meat. At the beginning, six groups with 40 one day old chicks Cobb 500 hybrid line, with five replications was formed. Chickens were fed with three mixtures of 21, 20 and 18% protein, respectively. The experiment lasted 42 days. The use of different types of oils in the diet did not exhibited statistically significant (P>0.05) differences in body weight of chickens. The control group achieved final body weight of 2704 g and 2695 g, and the experimental groups in a row 2735, 2645, 2735 and 2670g. The use of flax oil and rapeseed oil changes the fatty acid composition of lipids. Replacing rapeseed with soybean oil reduces the percentage of palmitic, stearic and linoleic acids, and increases the share of oleic and linolenic acids in the abdominal fat pad. The inclusion of flax oil in the diet of chickens in an amounts of 4% and 8% increase the amount of linoleic acid to 63% and 203%, which was statistically highly significant (P<0.01) difference compare to the control groups I and II, whereas the amount of linoleic acid is reduced by 14% and 33%. Dietary addition of vegetable oils in this experiment did not show any improvement of chicken breast meat sensory quality, but lipids of meat was improved with the higher levels of PUFAs which contributes to a higher quality of gained chicken meat

Productive characteristics and body measurements of alpine goats raised under smallholder production systems in central Serbia

The purpose of this study was to evaluate present level of productivity and determine linear body traits of Alpine goats raised in Serbia on smallholder farms. Data were collected from 22 smallholder farms located in Belgrade district, with total of 330 purebred Alpine does 2-9 years of age, 145 yearling does and 476 kids. Traits measured were: body weight of does, body weight of kids at birth, 30 days of age and at weaning (90-120 days), prolificacy of mature and yearling (primiparous) does, six linear body traits of does (wither height, body length, hearth girth, chest depth, chest width, pelvic width) and milk production (milk yield, milk fat and milk protein content). The analysis showed the average body weight of does to be 54.96 kg, while the average body weight of kids at birth, 30 days of age and weaning was 2.73 kg, 8.7 kg and 18.3 kg., respectively. Prolificacy was 144% in mature and 125% in yearling does. Measurements of linear body traits were: wither height 67.87 cm, body length 71.92 cm, hearth girth 81.79 cm, chest depth 32.93, chest width 21.49 cm and pelvic width 17.63 cm. Among dairy production traits, following results were obtained: lactation length 220.73 days, total milk yield 531.66 kg, milk fat content 3.33% and milk protein content 3.16%. It was concluded that the overall productivity of Alpine goats raised under smallholder production systems in Serbia is satisfying. Giving the fact that these animals are usually kept under poor conditions, many of these productive traits are very good