738 research outputs found

    Quiescent Radio Emission from Southern Late-type M Dwarfs and a Spectacular Radio Flare from the M8 Dwarf DENIS 1048-3956

    Full text link
    We report the results of a radio monitoring program conducted at the Australia Telescope Compact Array to search for quiescent and flaring emission from seven nearby Southern late-type M and L dwarfs. Two late-type M dwarfs, the M7 V LHS 3003 and the M8 V DENIS 1048-3956, were detected in quiescent emission at 4.80 GHz. The observed emission is consistent with optically thin gyrosynchrotron emission from mildly relativistic (~1-10 keV) electrons with source densities n_e ~ 10 G magnetic fields. DENIS 1048-3956 was also detected in two spectacular, short-lived flares, one at 4.80 GHz (peak f_nu = 6.0+/-0.8 mJy) and one at 8.64 GHz (peak f_nu = 29.6+/-1.0 mJy) approximately 10 minutes later. The high brightness temperature (T_B >~ 10^13 K), short emission period (~4-5 minutes), high circular polarization (~100%), and apparently narrow spectral bandwidth of these events imply a coherent emission process in a region of high electron density (n_e ~ 10^11-10^12 cm^-3) and magnetic field strength (B ~ 1 kG). If the two flare events are related, the apparent frequency drift in the emission suggests that the emitting source either moved into regions of higher electron or magnetic flux density; or was compressed, e.g., by twisting field lines or gas motions. The quiescent fluxes from the radio-emitting M dwarfs violate the Gudel-Benz empirical radio/X-ray relations, confirming a trend previously noted by Berger et al. (abridged)Comment: 28 pages, 8 figures, accepted for publication in Ap

    Landowning, Status and Population Growth

    Get PDF
    This paper considers the effects of the landowning and land reforms on economic and demographic growth by a family-optimization model with endogenous fertility and status-seeking. A land reform provides the peasant with strong incentives to limit their family size and to improve the productivity of the land. Even though the income effect due to the land reform tends to raise fertility, a strong enough status-effect outweighs it, thus generating a decrease in population growth. The European demographic history provides supporting anecdotal evidence for this theoretical result

    Semi-Hard Scattering Unraveled from Collective Dynamics by Two-Pion Azimuthal Correlations in 158 A GeV/c Pb + Au Collisions

    Full text link
    Elliptic flow and two-particle azimuthal correlations of charged hadrons and high-pTp_T pions (pT>p_T> 1 GeV/cc) have been measured close to mid-rapidity in 158A GeV/cc Pb+Au collisions by the CERES experiment. Elliptic flow (v2v_2) rises linearly with pTp_T to a value of about 10% at 2 GeV/cc. Beyond pTp_T\approx 1.5 GeV/cc, the slope decreases considerably, possibly indicating a saturation of v2v_2 at high pTp_T. Two-pion azimuthal anisotropies for pT>p_T> 1.2 GeV/cc exceed the elliptic flow values by about 60% in mid-central collisions. These non-flow contributions are attributed to near-side and back-to-back jet-like correlations, the latter exhibiting centrality dependent broadening.Comment: Submitted to Phys. Rev. Letters, 4 pages, 5 figure

    e+e--pair production in Pb-Au collisions at 158 GeV per nucleon

    Get PDF
    We present the combined results on electron-pair production in 158 GeV/n {Pb-Au} (s\sqrt{s}= 17.2 GeV) collisions taken at the CERN SPS in 1995 and 1996, and give a detailed account of the data analysis. The enhancement over the reference of neutral meson decays amounts to a factor of 2.31±0.19(stat.)±0.55(syst.)±0.69(decays)\pm0.19 (stat.)\pm0.55 (syst.)\pm0.69 (decays) for semi-central collisions (28% σ/σgeo\sigma/\sigma_{geo}) when yields are integrated over m>m> 200 MeV/c2c^2 in invariant mass. The measured yield, its stronger-than-linear scaling with NchN_{ch}, and the dominance of low pair ptp_t strongly suggest an interpretation as {\it thermal radiation} from pion annihilation in the hadronic fireball. The shape of the excess centring at mm\approx 500 MeV/c2c^2, however, cannot be described without strong medium modifications of the ρ\rho meson. The results are put into perspective by comparison to predictions from Brown-Rho scaling governed by chiral symmetry restoration, and from the spectral-function many-body treatment in which the approach to the phase boundary is less explicit.Comment: 39 pages, 40 figures, to appear in Eur.Phys.J.C. (2005

    SPOrt: an Experiment Aimed at Measuring the Large Scale Cosmic Microwave Background Polarization

    Get PDF
    SPOrt (Sky Polarization Observatory) is a space experiment to be flown on the International Space Station during Early Utilization Phase aimed at measuring the microwave polarized emission with FWHM = 7deg, in the frequency range 22-90 GHz. The Galactic polarized emission can be observed at the lower frequencies and the polarization of Cosmic Microwave Background (CMB) at 90 GHz, where contaminants are expected to be less important. The extremely low level of the CMB Polarization signal (< 1 uK) calls for intrinsically stable radiometers. The SPOrt instrument is expressly devoted to CMB polarization measurements and the whole design has been optimized for minimizing instrumental polarization effects. In this contribution we present the receiver architecture based on correlation techniques, the analysis showing its intrinsic stability and the custom hardware development carried out to detect such a low signal.Comment: 9 pages, 5 figures, conference proceeding, to appear in "Polarimetry in Astronomy", SPIE Symposium on 'Astronomical Telescopes and Instrumentation', Waikoloa, August 22-28 200

    Тепличное хозяйство – обзор текущего состояния отрасли АПК России

    Get PDF
    Relevance. Population growth and income growth, especially in urban areas, are already causing an increase in market demand as consumers seek to optimize their nutrition. Increased vegetable production to meet this demand creates important economic opportunities, especially for greenhouses.Materials and methods. The purpose of the research is to analyze the stages of development of domestic vegetable growing in greenhouses and the problems of organic greenhouse farming in the Russian Federation. The methods used in economic science were used. The research information base  was compiled by official state statistics; normative legal acts of federal and regional levels; data of the Ministry of Agriculture of the Russian Federation; reference materials of specialized publications on the subject under study; materials from participants in the market of vegetables of greenhouses, own research and other.Results. The development of protected ground in Russia has repeatedly been given the attention of state bodies. The main stages of the formation of domestic vegetable growing of protected soil are considered; trends characteristic of the domestic market, which is subject to the influence of external and internal factors. Currently, in general, vegetable growing in closed ground is showing positive dynamics. Since 2000, the production of greenhouse vegetables has increased by 3.6 times. The gross growth of vegetables is due to the positive dynamics of two components: an increase in the area of new generation greenhouses and an increase in yield per meter of inventory. Most of the greenhouses being built and commissioned are high-tech complexes, the construction of which was made possible thanks to  state support. The competitiveness of domestic vegetable products is possible in the formation of a favorable investment climate for the development of innovative technologies and increase the  profitability of greenhouse plants. This can be achieved by limiting the growth of prices for material and technical resources (equipment, fertilizers, protective equipment, energy, etc.); increase in the share of vegetable producers in the final market price; stabilization of decent prices for vegetables; increasing incomes (to maintain consumer demand); accelerated technical and technological modernization of production; maintaining state support; a ban on the return of unsold products. Pursuant to Federal Law No. 280-ФЗ “On Organic Production and Amending Certain Legislative Acts of the Russian Federation” dated January 1, 2020, it is necessary to provide public and private financing for organic greenhouse farming as part of the research program of the Federal Research Center for Vegetable Production as the only state research institute for vegetable growing.Актуальность. Рост населения и увеличение доходов, особенно в городских районах, вызывают увеличение спроса на рынке, поскольку потребители стремятся оптимизировать свое питание. Увеличение производства овощей для удовлетворения этого спроса создает важные экономические возможности, особенно для  тепличных хозяйств.Методы. В работе проанализированы этапы развития отечественного овощеводства защищенного грунта и проблемы органического хозяйства в РФ. Для анализа использованы методы, применяемые в экономической науке. Информационную базу исследования составили данные официальной государственной статистики; нормативные акты федеральных и региональных уровней; данные Министерства сельского хозяйства Российской Федерации; справочные материалы специализированных изданий по исследуемой тематике; материалы, поступающие от участников рынка овощей защищенного грунта, собственные исследования; данные отраслевых порталов, сайты производителей продукции защищенного грунта, статьи и обзоры.Результаты. В целом овощеводство защищенного грунта демонстрирует положительную динамику: за период с 2000 года производство овощей защищенного грунта увеличилось в 3,6 раза. Валовой рост овощей происходит благодаря положительной динамике двух составляющих: увеличения площадей теплиц нового поколения и роста урожайности с метра инвентарной площади. Большая часть строящихся и вводимых теплиц является высокотехнологичными комплексами, строительство которых стало возможным благодаря государственной поддержке. Передовые агротехнологии стали ведущим фактором развития тепличного овощеводства и позволили решать вопросы урожайности и качества продукции, а также насыщения российского рынка овощами отечественного производства. Конкурентоспособность отечественной овощной продукции возможна при формировании благоприятного инвестклимата для освоения инновационных технологий и повышения доходности тепличных комбинатов. Это может быть достигнуто через ограничение роста цен на материально-технические ресурсы; увеличение доли овощепроизводителей в конечной рыночной цене; стабилизацию достойных цен на овощи; повышение доходов населения (для поддержания потребительского спроса); ускоренную технико-технологическую модернизацию производства; сохранение государственной поддержки; запрет на возврат нереализованной продукции. Во исполнение Федерального закона №280-ФЗ «Об органической продукции и о внесении изменений в отдельные законодательныеакты Российской Федерации» от 1 января 2020 года необходимо предусмотреть государственное и частное финансирование по органическому тепличному хозяйству в рамках исследовательской программы ФГБНУ «Федеральный научный центр овощеводства», как единственного государственного научно-исследовательского института по овощеводству

    Recoil Polarization Measurements of the Proton Electromagnetic Form Factor Ratio to Q^2 = 8.5 GeV^2

    Full text link
    Among the most fundamental observables of nucleon structure, electromagnetic form factors are a crucial benchmark for modern calculations describing the strong interaction dynamics of the nucleon's quark constituents; indeed, recent proton data have attracted intense theoretical interest. In this letter, we report new measurements of the proton electromagnetic form factor ratio using the recoil polarization method, at momentum transfers Q2=5.2, 6.7, and 8.5 GeV2. By extending the range of Q2 for which GEp is accurately determined by more than 50%, these measurements will provide significant constraints on models of nucleon structure in the non-perturbative regime

    Azimuthal anisotropy and correlations in the hard scattering regime at RHIC

    Get PDF
    Azimuthal anisotropy (v2v_2) and two-particle angular correlations of high pTp_T charged hadrons have been measured in Au+Au collisions at sNN\sqrt{s_{NN}}=130 GeV for transverse momenta up to 6 GeV/c, where hard processes are expected to contribute significantly. The two-particle angular correlations exhibit elliptic flow and a structure suggestive of fragmentation of high pTp_T partons. The monotonic rise of v2(pT)v_2(p_T) for pT<2p_T<2 GeV/c is consistent with collective hydrodynamical flow calculations. At \pT>3 GeV/c a saturation of v2v_2 is observed which persists up to pT=6p_T=6 GeV/c.Comment: As publishe

    Azimuthal anisotropy of K0S and Lambda + Lambda -bar production at midrapidity from Au+Au collisions at sqrt[sNN]=130 GeV

    Get PDF
    We report STAR results on the azimuthal anisotropy parameter v2 for strange particles K0S, Lambda , and Lambda -bar at midrapidity in Au+Au collisions at sqrt[sNN]=130 GeV at the Relativistic Heavy Ion Collider. The value of v2 as a function of transverse momentum, pt, of the produced particle and collision centrality is presented for both particles up to pt~3.0 GeV/c. A strong pt dependence in v2 is observed up to 2.0 GeV/c. The v2 measurement is compared with hydrodynamic model calculations. The physics implications of the pt integrated v2 magnitude as a function of particle mass are also discussed.Alle Autoren: C. Adler, Z. Ahammed, C. Allgower, J. Amonett, B. D. Anderson, M. Anderson, G. S. Averichev, J. Balewski, O. Barannikova, L. S. Barnby, J. Baudot, S. Bekele, V. V. Belaga, R. Bellwied, J. Berger, H. Bichsel, A. Billmeier, L. C. Bland, C. O. Blyth, B. E. Bonner, A. Boucham, A. Brandin, A. Bravar, R. V. Cadman, H. Caines, M. Calderón de la Barca Sánchez, A. Cardenas, J. Carroll, J. Castillo, M. Castro, D. Cebra, P. Chaloupka, S. Chattopadhyay, Y. Chen, S. P. Chernenko, M. Cherney, A. Chikanian, B. Choi, W. Christie, J. P. Coffin, T. M. Cormier, J. G. Cramer, H. J. Crawford, W. S. Deng, A. A. Derevschikov, L. Didenko, T. Dietel, J. E. Draper, V. B. Dunin, J. C. Dunlop, V. Eckardt, L. G. Efimov, V. Emelianov, J. Engelage, G. Eppley, B. Erazmus, P. Fachini, V. Faine, K. Filimonov, E. Finch, Y. Fisyak, D. Flierl, K. J. Foley, J. Fu, C. A. Gagliardi, N. Gagunashvili, J. Gans, L. Gaudichet, M. Germain, F. Geurts, V. Ghazikhanian, O. Grachov, V. Grigoriev, M. Guedon, E. Gushin, T. J. Hallman, D. Hardtke, J. W. Harris, T. W. Henry, S. Heppelmann, T. Herston, B. Hippolyte, A. Hirsch, E. Hjort, G. W. Hoffmann, M. Horsley, H. Z. Huang, T. J. Humanic, G. Igo, A. Ishihara, Yu. I. Ivanshin, P. Jacobs, W. W. Jacobs, M. Janik, I. Johnson, P. G. Jones, E. G. Judd, M. Kaneta, M. Kaplan, D. Keane, J. Kiryluk, A. Kisiel, J. Klay, S. R. Klein, A. Klyachko, A. S. Konstantinov, M. Kopytine, L. Kotchenda, A. D. Kovalenko, M. Kramer, P. Kravtsov, K. Krueger, C. Kuhn, A. I. Kulikov, G. J. Kunde, C. L. Kunz, R. Kh. Kutuev, A. A. Kuznetsov, L. Lakehal-Ayat, M. A. C. Lamont, J. M. Landgraf, S. Lange, C. P. Lansdell, B. Lasiuk, F. Laue, A. Lebedev, R. Lednický, V. M. Leontiev, M. J. LeVine, Q. Li, S. J. Lindenbaum, M. A. Lisa, F. Liu, L. Liu, Z. Liu, Q. J. Liu, T. Ljubicic, W. J. Llope, G. LoCurto, H. Long, R. S. Longacre, M. Lopez-Noriega, W. A. Love, T. Ludlam, D. Lynn, J. Ma, R. Majka, S. Margetis, C. Markert, L. Martin, J. Marx, H. S. Matis, Yu. A. Matulenko, T. S. McShane, F. Meissner, Yu. Melnick, A. Meschanin, M. Messer, M. L. Miller, Z. Milosevich, N. G. Minaev, J. Mitchell, V. A. Moiseenko, C. F. Moore, V. Morozov, M. M. de Moura, M. G. Munhoz, J. M. Nelson, P. Nevski, V. A. Nikitin, L. V. Nogach, B. Norman, S. B. Nurushev, G. Odyniec, A. Ogawa, V. Okorokov, M. Oldenburg, D. Olson, G. Paic, S. U. Pandey, Y. Panebratsev, S. Y. Panitkin, A. I. Pavlinov, T. Pawlak, V. Perevoztchikov, W. Peryt, V. A Petrov, M. Planinic, J. Pluta, N. Porile, J. Porter, A. M. Poskanzer, E. Potrebenikova, D. Prindle, C. Pruneau, J. Putschke, G. Rai, G. Rakness, O. Ravel, R. L. Ray, S. V. Razin, D. Reichhold, J. G. Reid, F. Retiere, A. Ridiger, H. G. Ritter, J. B. Roberts, O. V. Rogachevski, J. L. Romero, A. Rose, C. Roy, V. Rykov, I. Sakrejda, S. Salur, J. Sandweiss, A. C. Saulys, I. Savin, J. Schambach, R. P. Scharenberg, N. Schmitz, L. S. Schroeder, A. Schüttauf, K. Schweda, J. Seger, D. Seliverstov, P. Seyboth, E. Shahaliev, K. E. Shestermanov, S. S. Shimanskii, V. S. Shvetcov, G. Skoro, N. Smirnov, R. Snellings, P. Sorensen, J. Sowinski, H. M. Spinka, B. Srivastava, E. J. Stephenson, R. Stock, A. Stolpovsky, M. Strikhanov, B. Stringfellow, C. Struck, A. A. P. Suaide, E. Sugarbaker, C. Suire, M. Šumbera, B. Surrow, T. J. M. Symons, A. Szanto de Toledo, P. Szarwas, A. Tai, J. Takahashi, A. H. Tang, J. H. Thomas, M. Thompson, V. Tikhomirov, M. Tokarev, M. B. Tonjes, T. A. Trainor, S. Trentalange, R. E. Tribble, V. Trofimov, O. Tsai, T. Ullrich, D. G. Underwood, G. Van Buren, A. M. VanderMolen, I. M. Vasilevski, A. N. Vasiliev, S. E. Vigdor, S. A. Voloshin, F. Wang, H. Ward, J. W. Watson, R. Wells, G. D. Westfall, C. Whitten, Jr., H. Wieman, R. Willson, S. W. Wissink, R. Witt, J. Wood, N. Xu, Z. Xu, A. E. Yakutin, E. Yamamoto, J. Yang, P. Yepes, V. I. Yurevich, Y. V. Zanevski, I. Zborovský, H. Zhang, W. M. Zhang, R. Zoulkarneev, and A. N. Zubarev (STAR Collaboration
    corecore