Electron Screening in the 7Be + p -->8B + photon reaction

We evaluate the effect of screening by bound electron in the 7Be + p --> 8B + photon reaction, where 7Be target contains bound electron, in the framework of the adiabatic representation of the three particle problem. A comparison with two other approximations (united atom and folding) is presented. A good agreement between the ``united atom'' approximation and the exact solution is found. We also discuss the screening corrections induced by two K-shell electrons on a 7Be target. The bound electron screening effect consequences for 7Be and 8B solar neutrino fluxes are discussed.Comment: Revised paper. (RevTeX, 6 pages, 2 PS-figures

Realizations of the Lie superalgebra q(2) and applications

The Lie superalgebra q(2) and its class of irreducible representations V_p of dimension 2p (p being a positive integer) are considered. The action of the q(2) generators on a basis of V_p is given explicitly, and from here two realizations of q(2) are determined. The q(2) generators are realized as differential operators in one variable x, and the basis vectors of V_p as 2-arrays of polynomials in x. Following such realizations, it is observed that the Hamiltonian of certain physical models can be written in terms of the q(2) generators. In particular, the models given here as an example are the sphaleron model, the Moszkowski model and the Jaynes-Cummings model. For each of these, it is shown how the q(2) realization of the Hamiltonian is helpful in determining the spectrum.Comment: LaTeX file, 15 pages. (further references added, minor changes in section 5

The return of the bursts: Thermonuclear flashes from Circinus X-1

We report the detection of 15 X-ray bursts with RXTE and Swift observations of the peculiar X-ray binary Circinus X-1 during its May 2010 X-ray re-brightening. These are the first X-ray bursts observed from the source after the initial discovery by Tennant and collaborators, twenty-five years ago. By studying their spectral evolution, we firmly identify nine of the bursts as type I (thermonuclear) X-ray bursts. We obtain an arcsecond location of the bursts that confirms once and for all the identification of Cir X-1 as a type I X-ray burst source, and therefore as a low magnetic field accreting neutron star. The first five bursts observed by RXTE are weak and show approximately symmetric light curves, without detectable signs of cooling along the burst decay. We discuss their possible nature. Finally, we explore a scenario to explain why Cir X-1 shows thermonuclear bursts now but not in the past, when it was extensively observed and accreting at a similar rate.Comment: Accepted for publication in The Astrophysical Journal Letters. Tables 1 & 2 merged. Minor changes after referee's comments. 5 pages, 4 Figure

Chemical Composition and Energy Nutritional Value of the Meat of Guinea Fowls (Numidameleagris), Fattened to different Ages

The aim of the study was to investigate the chemical composition and energy content of the meat of young Guinea-fowls, with different duration of the fattening period, raised in a free-range, semi-intensive production system. The authors establish the following data: dry matter content- from 27.08 to 28.82% in breast muscle and from 23.83 to 26.56% in thigh muscle; crude protein in dry matter –from 86.19to 93.54% in breastand from 82.02 to 87.84% in thigh muscle; crude fat in dry matter - from 5.64 to 7.58% in breast and from 9.02 to 11.05% in thigh muscles. The average energy content in 100 g dry matter varies from 23.7 (breast muscle, 16 weeks of age) to 25.07 kJ (thigh muscle, 24 weeks of age)

Movement of cadmium and lead in anthropogenically formed trophic chains of a pasture type

ABSTRACT: An investigation on the movement of Lead (Pb) and cadmium (Cd) in a trophic chain in 2 villages (industrial polluted and non polluted) has been conducted. The contents of the 2 heavy metals in the soil, food and in different organs of young kids, so as their transfer in the 3 trophic levels (using different static and dynamic methods of recalculation) have been established. The authors show, that it is expedient to determine quantitatively the chemical heterogeneity at the heterotrophic levels applying two criteria: along with the dynamic criterion “Clarc of concentration”(Cc), used up to know, to include also “Factor of bioaccumulation” (FB), which shows the real value of accumulation or dispersal of the chemical element according to its content in soil or at the trophic level of the autotrophic organisms. The increased Cc of lead /4,72/ and cadmium /49,14/ in soil is not the reason for the concentration in the nutrition chain at the level of the autotrophic organisms and at the level of the organisms phytophages /kids/. The studies of the FB show that the technogenically high Clarc of lead and cadmium in the ecotope is the reason for some changes in the metabolism, enabling the dispersal of lead along the trophic chain, the values falling down to 0,05 – 0,02 compared to its content in the ecotope, and, of cadmium – down to 0,03 – 0,15 in the tested organs and tissues. РЕЗЮМЕ: Проведено е изследване за движението на олово (Pb) и кадмий (Cd) в трофична верига в две села(промишлено замърсено и незамърсено). Установено е съдържанието на двата тежки метала в почвата, храната и различните органи на млади ярета и трансферът им в трите трофични нива, използвайки различни статични и динамични методи на изчисление. Авторите доказват, че е възможно количественото определяне на химичната хетерогенност на хетеротрофните нива, използвайки два критерия: наред с динамичния критерий “Кларк на концентрация” (Сс), използван досега, се включва и “Фактор на биоакумулация” (FB), който показва реалната стойност на натрупване или разсейване на химичния елемент според съдържанието му в почвата или на трофично ниво в автотрофния организъм. Повишеният Сс на олово /4,72/ и кадмий /49,14/ в почвата не е причина за концентрацията им в хранителната верига на нивото на автотрофните организми и на нивото на организмите-фитофаги /ярета/. Изследванията на FB показват, че техногенно високият кларк на олово и кадмий в екотопа е причина за някои промени в метаболизма, способстващи за разпръскване на оловото по трофичната верига и спада на стойностите до 0,05 – 0,02 в сравнение със съдържанието му в екотопа, и на кадмия – до 0,03 – 0,15 в изследваните органи и тъкани

COMPARATIVE STUDY OF THE AMINOACID’S TRUE DIGESTIBILITY OF DIFFERENT CLOVER (TRIFOLIUM) VARIETIES IN EXPERIMENTS WITH GANDERS

The true digestibility of amino acids of 5 groups of different Trifolium varieties and hybrids was established by using the balance method adapted for geese. Digestibility of the most important amino acids Lysine varies from 70.40 (for tetraplod red clover) to 81.78 (for medium leafy white clover varieties); for Methionine from 60.54 (for Trifolium repens f. giganteum) to 89.42 (diploid red clover); Cystine from 71.03 (for medium leafy white clover) to 87.72 (for Trifolium repens f. giganteum). Amino acids digestibility well correlates with the crude protein content, crude fiber and the total amount of amino acids in the dry matter of the forages and can be predicted with linear regression equations