515,915 research outputs found

    Peculiar Velocity Reconstruction with Fast Action Method: Tests on Mock Redshift Surveys

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    We present extensive tests of the Fast Action Method (FAM) for recovering the past orbits of mass tracers in an expanding universe from their redshift-space coordinates at the present epoch. The tests focus on the reconstruction of present-day peculiar velocities using mock catalogs extracted from high resolution NN-body simulations. The method allows for a self-consistent treatment of redshift-space distortions by direct minimization of a modified action for a cosmological gravitating system. When applied to ideal, volume limited catalogs, FAM recovers unbiased peculiar velocities with a 1-D, 1\sigma error of ~220 km/s, if velocities are smoothed on a scale of 5 Mpc/h. Alternatively, when no smoothing is applied, FAM predicts nearly unbiased velocities for objects residing outside the highest density regions. In this second case the 1\sigma$error decreases to a level of ~150 km/s. The correlation properties of the peculiar velocity fields are also correctly recovered on scales larger than 5 Mpc/h. Similar results are obtained when FAM is applied to flux limited catalogs mimicking the IRAS PSCz survey. In this case FAM reconstructs peculiar velocities with similar intrinsic random errors, while velocity-velocity correlation properties are well reproduced beyond scales of ~8 Mpc/h. We also show that FAM provides better velocity predictions than other, competing methods based on linear theory or Zel'dovich approximation. These results indicate that FAM can be successfully applied to presently available galaxy redshift surveys such as IRAS PSCz.Comment: 26 pages, 16 figures. Figures 1,2,3,4,5,7,11,12 and 16 are also included as separate gif files. Added 2 new sections(5.3 and 6.3) and figures (11 and 16). More discussion added to section 7 (Summary and Conclusions). MNRAS accepte

    A COMPARISON OF SELECTED MILK INDICATORS IN ORGANIC HERDS WITH CONVENTIONAL HERD AS REFERENCE

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    In a historical sense, current organic farming is an old-new alternative under changed world conditions. Organic dairying (O) is an alternative of friendly use of the environment in time of presupposed global climate changes. Potential impact of organic farming on raw cow-milk quality, composition and properties, as conpared to conventional milk production (C), were evaluatedin this paper on the basis of selectedm ilk indicators (MIs). Total solids, whey volume, pH of milk fermentation ability (FAM-pH), FAM streptococci, FAM noble lactic acid bacteria, I and Cu were higher in C milk (P0.05) were observed in pH, rennet coagulation time, curd quality, FAM lactobacilli and streptococci/lactobacilli, Na, Mn and Zn. In general, the differences were a little more advantageous for O milk from both technological and nutritional point of view, particularly because of AS (0.461 .81m m), FAM-T (27.3 4.6 ) , Ca (1172 < l257 mg.kg-1)P, ( 950 < l004 mg. kg-1) and Mg 107.4<ll2.0mg.kg{) results. Organic milk can also produce better environment for yoghurt fermentation. Nevertheless, the results obtained should not be overestimated as both sources produced milk of good quality. Additional results are needed to prove organic milk benefits

    Use of Ovulation Predictor Kits as Adjuncts When Using Fertility Awareness Methods (FAMs): A Pilot Study

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    Purpose: Difficult clinical signs such as confusing cervical mucus or erratic basal body temperature can make the use of fertility awareness methods (FAMs) difficult in some cases. The goal of this study was to assess the feasibility of using a cheap urinary luteinizing hormone (LH)–surge identification kit as an adjunct to identify the infertile phase after ovulation when facing these scenarios. Methods: The study used a block-allocation, crossover, 2-arm methodology (LH kit/FAM vs FAM only). Comparison of the 2 arms was done with regard to the accuracy of identification (yes/no) of the luteal phase in each cycle as confirmed by serum progesterone concentrations. Results: We recruited 23 Canadian women currently using FAM, aged 18 to 48 years, who have had menstrual cycles 25 to 35 days long for the past 3 months and perceive themselves to have difficulty with identifying the infertile phase after ovulation. LH kits identified 100% of the luteal phases, whereas FAM indentified 87% (statistically significant). In those identified cycles, LH kits provided a mean of 10.3 days of infertility, and FAM only provided 10 days of infertility (not statistically significant). Conclusions: Among this population, LH kits may offer an adjunct for women who may wish to have an additional double-check. However, there are still clinical circumstances when even an LH kit does not provide confirmation. More research in this area is encouraged

    Feasibility of the finite amplitude method in covariant density functional theory

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    Self-consistent relativistic random-phase approximation (RPA) in the radial coordinate representation is established by using the finite amplitude method (FAM). Taking the isoscalar giant monopole resonance in spherical nuclei as example, the feasibility of the FAM for the covariant density functionals is demonstrated, and the newly developed methods are verified by the conventional RPA calculations. In the present relativistic RPA calculations, the effects of the Dirac sea can be automatically taken into account in the coordinate-space representation. The rearrangement terms due to the density-dependent couplings can be implicitly calculated without extra computational costs in both iterative and matrix FAM schemes.Comment: 12 pages, 5 figure

    Multipole strength function of deformed superfluid nuclei made easy

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    We present an efficient method for calculating strength functions using the finite amplitude method (FAM) for deformed superfluid heavy nuclei within the framework of the nuclear density functional theory. We demonstrate that FAM reproduces strength functions obtained with the fully self-consistent quasi-particle random-phase approximation (QRPA) at a fraction of computational cost. As a demonstration, we compute the isoscalar and isovector monopole strength for strongly deformed configurations in 240^{240}Pu by considering huge quasi-particle QRPA spaces. Our approach to FAM, based on Broyden's iterative procedure, opens the possibility for large-scale calculations of strength distributions in well-bound and weakly bound nuclei across the nuclear landscape.Comment: 5 pages, 3 figure

    Low energy collective modes of deformed superfluid nuclei within the finite amplitude method

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    Background: The major challenge for nuclear theory is to describe and predict global properties and collective modes of atomic nuclei. Of particular interest is the response of the nucleus to a time-dependent external field that impacts the low-energy multipole and beta-decay strength. Purpose: We propose a method to compute low-lying collective modes in deformed nuclei within the finite amplitude method (FAM) based on the quasiparticle random-phase approximation (QRPA). By using the analytic property of the response function, we find the QRPA amplitudes by computing the residua of the FAM amplitudes by means of a contour integration around the QRPA poles in a complex frequency plane. Methods: We use the superfluid nuclear density functional theory with Skyrme energy density functionals, FAM-QRPA approach, and the conventional matrix formulation of the QRPA (MQRPA). Results: We demonstrate that the complex-energy FAM-QRPA method reproduces low-lying collective states obtained within the conventional matrix formulation of the QRPA theory. Illustrative calculations are performed for the isoscalar monopole strength in deformed 24Mg and for low-lying K = 0 quadrupole vibrational modes of deformed Yb and Er isotopes. Conclusions: The proposed FAM-QRPA approach allows one to efficiently calculate low-lying collective modes in spherical and deformed nuclei throughout the entire nuclear landscape, including shape-vibrational excitations, pairing vibrational modes, and beta-decay rates.Comment: 9 pages, 2 figures, submitted to Phys. Rev.

    Araneae (I.)

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    The present paper contains an account of that portion of the Araneae collected by Dr. Lt SCHULTZE in South Africa, which falls into the families given in the following list, the numbers in the list being the total number of examples collected of each family and the number of species identified or described in this paper: Fam. Aviculariidae 66 examples 11 species (10 new) Fam. Dictynidae 14 examples 3 species (1 new) Fam. Eresidae 1057 examples 10 species ( 6 new) Fam. Sicariidae 46 examples 7 species ( 4 new) Fam. Dysdeddae 144 examples 6 species ( 4 new) Fam. Caponiidae 26 examples 1 species Fam. Prodidomidae 1 example 1 species Fam. Drassidae 557 examples 27 species (21 new) Totals: 1911 examples 66 species (46 new) Dr. SCHULTZE is to be congratulated on the large number of specimens obtained by him. The most extensive collections were made in Little Namaqualand, but a considerable number of specimens were also obtained in Great Namaqualand (including Possession Island) and in the Kalahari (in the Bechuanaland Protectorate), while a small number came from Southern Hereroland (S. Damaraland) and from the Cape Peninsula. With the exception of the last, all these localities represent practically new fields for the collector of Aranee, for, so far as I am aware, no extensive collections have ever been made in any of them before, and only a. few odd species have been recorded from time to time. Accordingly more than two-thirds of the total number of species described or identified in this paper are new to science, although the genera to which they belong are in all cases identical with those of the other and better known dry portions of the interior of Cape Colony. If the gregarious Eresidae (StegodyphuS) be excluded from the above list, it will be seen that the Drassidae are by far the most numerous both in individuals and species, being followed in number by the non-gregarious Eresidae and the Dysderidae. But it must be borne in mind that the underground Aviculariidae, particularly the Trap-door forms, were probably not collected as thoroughly as the other spiders, owing to the extreme difficulty generally experienced in discovering their retreats. Nevertheless Dr. SCHULTZE obtained at least 7 species, which may with confidence be placed among the trap-door building forms, belonging to the genera ldiops, Stasimopus, Pelmatorycter and Ancylotrypa. The two largest spiders obtained were a large Harpactira from Great and Little Namaqualand, and a new Ceratogyrus from the Kalahari, the latter having a peculiar horn in the middle of the cephalothorax above
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