362 research outputs found
Giant Cyclones in Gaseous Discs of Spiral Galaxies
We report detection of giant cyclonic vortices in the gaseous disc of the
spiral galaxy NGC 3631 in the reference frame rotating with the spiral pattern.
A presence of such structures was predicted by the authors for galaxies, where
the radial gradient of the perturbed velocity exceeds that of the rotational
velocity. This situation really takes place in NGC 3631.Comment: 13 pages, 4 EPS and 3 PS figure
НОВОЕ НАПРАВЛЕНИЕ НАУЧНЫХ ИССЛЕДОВАНИЙ ПО ИЗУЧЕНИЮ ПРОДУКТИВНОСТИ ЖИВОТНЫХ В СВЯЗИ С РАЗНОЙ КОСМОФИЗИЧЕСКОЙ АКТИВНОСТЬЮ
Brief results of research at the Department of Zootechnics of the PFUR in more than 30 years are reported on the relationship between cosmophysical activity and animal productivity (the rhythm of milk yield of cows and the chemical composition of milk, the biochemical composition of cows' blood). It is established that in even and odd 11-year solar cycles, animals react differently to cosmophysical activity. In even cycles, the increase in solar activity contributes to the growth of milk yields. In odd cycles, increasing solar activity reduces milk yield. The data of scientific observations, covering the periods of even and odd cycles, should be grouped and analyzed separately by cycles. Within 2—3 years, at the lowest peak of solar activity, and 2—3 years — at the top peak of activity (with the change of magnetic poles on the Sun) minimal and unreliable correlations are noted. The strongest correlation was noted in the middle of the rise or decrease in solar activity. The rhythm of milk yield was noted regard-less of the lactation phase of cows. Approximately 1/3 of the time, milk yield increased, 1/3 — decreased and 1/3 — remained at the same level, with fluctuations, with periods from 2.7; 3.3; up to 5.5 days. With an increase in milk yield during 31.0% of lactation days, the content of fat and protein in milk decreased, respectively, 25.8 and 25.4% of the time. With a decrease in milk yield during 33.7% of lactation days, the fat and protein content did not change, respectively, 49.8 and 48.1% days. The most pronounced interval of rhythmicity of the concentration of fat and protein in milk from 2 to 2.5 days with an average value of 2.2 days was established. In addition rhythm 2.8; 3.4; 4.4; 8; 32; 41,1 and 72 days was marked. Approxi-mately with the same cycles in the milk, sugar concentrations, density and acidity were changed.Приведены краткие результаты исследований на кафедре зоотехнии РУДН более чем за 30 лет о взаимосвязи космофизической активности и продуктивности животных (ритмичности удоев коров и химического состава молока, биохимическом составе крови коров). Установлено, что в четные и нечетные 11-летние солнечные циклы животные по-разному реагируют на космофизические про-явления. В четные циклы повышение солнечной активности способствует росту удоев. В нечетные циклы повышение солнечной активности снижает удои. Данные научных наблюдений, охватывающих периоды четных и нечетных циклов, следует группировать и анализировать отдельно по циклам. В течение 2-3 лет на нижнем пике солнечной активности и 2-3 лет - на верхнем пике активности (при смене магнитных полюсов на Солнце) отмечаются минимальные и недостоверные корреляционные связи. Наиболее стабильные связи бывают в середине подъема или снижения солнечной активности. При этом ритмичность удоев отмечалась независимо от фазы лактации коров. Примерно 1/3 времени удои росли, 1/3 - снижались и 1/3 - оставались на одном уровне, при колебаниях суточных удоев с периодами от 2,7; 3,3 до 5,5 суток. При увеличении удоев в течение 31,0% дней лактации содержание жира и белка в молоке уменьшалось соответственно 25,8 и 25,4% времени. При снижении же удоев в течение 33,7% дней лактации содержание жира и белка не изменялось соответственно 49,8 и 48,1% дней. Наиболее выражен интервал ритмичности концентрации жира и белка в молоке от 2 до 2,5 суток со средним значением 2,2 дня; затем отмечается ритм 2,8; 3,4; 4,4; 8; 32; 41,1 и 72 суток. Примерно с такими же циклами в молоке изменялись концентрации сахара, плотности и кислотности
РЕЗУЛЬТАТЫ ПРИМЕНЕНИЯ ФОСФОМИЦИНА ДЛЯ ИМПРЕГНАЦИИ ОСТЕОЗАМЕЩАЮЩИХ МАТЕРИАЛОВ ПРИ ЛЕЧЕНИИ ХРОНИЧЕСКОГО ОСТЕОМИЕЛИТА
Aim – to evaluate in the experimental study in vitro the duration of antimicrobial activity of fosfomycin-impregnated bone cement and to study the dynamics of radiological and morphological changes depending on the local antibiotic therapy in two-stage treatment of chronic osteomyelitis in rabbits.Materials and methods. Duration of antimicrobial activity of bone cement (depuy cmw1 gentamicin) with fosfomycin in vitro was studied in comparison to cements with vancomycin and controls without additional antibiotics. Presence of the lysis zone of bacterial cultures was evaluated (Staphylococcus aureus ATCC6538 and ATCC33591, Klebsiella pneumoniae ATCC33495 and Escherichia coli ATCC25922) after application of 10 μl of the solution, collected from the cement samples after incubation for 24 hours. For the in vivo experiment, Chinchilla rabbits (n = 20) with local osteomyelitis of the tibia underwent two-stage treatment where substitution of the bone defect at stage I was performed with PMMA and stage II – with the bioresorbable material based on hydroxyapatite and triclacium phosphate (ReproBone). In an experience group (n = 10) before setting osteoreplacement materials with fosfomycin (group FOSFO), and by control (n = 10) – vancomycin (group VANCO). X-ray imaging was performed on the 1st and 21st day after installation of the cement spacer, and 45th day after substitution of the spacer with the bioresorbable material. Microbiological analysis of the samples was performed intraoperatively and on the 7th, 14th day after each stage. Histological study was conducted in both groups on the 14th, 21th day after stage I and 45th day after stage II of the treatment.Results. Maximal duration of antimicrobial activity in vitro was observed in samples of PMMA with fosfomycin whereas minimal – in control samples of gentamicin-based bone cement. Relief of the infection was attained in all animals while application of fosfomycin resulted in a more rapid elimination of the bacteria. Reaction of the adjacent tissue to the implanted material and results of X-ray imaging in both groups did not differ significantly. Long duration of the broad-spectrum antimicrobial activity of the bone cement with fosfomycin with the comparable perifocal reaction in vivo necessitates further study of the use of this antibiotic in bioresorbable materials for the treatment of osteomyelitis in clinical practice.Цель – оценить в эксперименте in vitro длительность антимикробной активности образцов импрегнированного фосфомицином костного цемента и изучить динамику рентгенологической и морфологической картины в зависимости от локальной антибактериальной терапии при двухэтапном лечении хронического остеомиелита у кроликов.Материал и методы. Изучали in vitro длительность антимикробной активности образцов импрегнированного фосфомицином костного цемента (depuy cmw1 gentamicin) в сравнении с импрегнацией ванкомицином и контрольными образцами без внесения дополнительного антибиотика. Оценивали наличие зоны лизиса бактериальной культуры (Staphylococcus aureus ATCC6538 и ATCC33591, Klebsiella pneumoniae ATCC33495 и Escherichia coli ATCC25922) в области нанесения 10 мкл инкубационного раствора после инкубации образца в течение 24 час. В эксперименте in vivo 20 кроликам породы Шиншилла c локальным очагом остеомиелита большеберцовой кости проводили двухэтапное лечение. На первом этапе костный дефект замещали костным цементом на основе полиметилметакрилата (ПММА), на втором этапе – биорезорбируемым материалом на основе гидроксиапатита и трикальцийфосфата (ReproBone). В опытной группе (n = 10) перед установкой остеозамещающие материалы импрегнировали фосфомицином (группа ФОСФО), а в контрольной группе (n = 10) – ванкомицином (группа ВАНКО). Рентгенологические исследования выполняли в первые и 21-е сутки после установки цементного спейсера, на 45-е сутки после удаления цементного спейсера и укладки биорезорбируемого материала. Бактериологические исследования выполняли интраоперационно, на 7-е и 14-е сутки после каждого этапа. Морфологические исследования выполняли в обеих группах на 14-е и 21-е сутки после первого этапа и на 45-е сутки после второго этапа лечения.Результаты. Максимальная продолжительность антимикробной активности in vitro установлена при использовании ПММА с фосфомицином, минимальная – для контрольных образцов из официнального гентамицин-содержащего цемента. В эксперименте in vivo у всех животных было достигнуто купирование инфекционного процесса, однако применение фосфомицина приводило к более быстрой эрадикации возбудителя. Реакции тканей, окружающих имплантированный материал, в обеих группах экспериментальных животных различались незначительно, рентгенологическая картина была схожей. Большая длительность антимикробного действия образцов костного цемента с фосфомицином в отношении широкого спектра возбудителей при сопоставимых перифокальных реакциях в эксперименте in vivo делает перспективным дальнейшее изучение данного антибиотика в составе остеозамещающих материалов при лечении остеомиелита в клинической практике
New Structures in Galactic Disks: Predictions and Discoveries
Original paper can be found at http://www.astrosociety.org/pubs/cs/222-252.html--Copyright Astronomical Society of the Pacific --Our main goal is to review: 1) some physical mechanisms which form the observed structures in galactic disks; 2) the discovery of new galactic structures predicted earlier. Specifically in the first part of the paper we discuss some questions associated with spiral structure. The second part is devoted to the prediction and discovery of giant vortices in gaseous disks of the grand design spiral galaxies using method of reconstruction of the full three-component velocity field from the observed line-of-sight velocity field. In the third part, we give some arguments in favour of existence of the slow bars in the grand design spiral galaxies
The spectrum features of UHECRs below and surrounding GZK
The energy spectrum of UHECRs is discussed on the basis of the Yakutsk array
database analysis. In the region E=0.1 to 30 EeV the showers are detected under
trigger-500, while at energies above 30 EeV the whole acceptance area for
trigger-1000 is used in order to utilize all the data available in the region
of GZK cutoff.Comment: Invited talk at CRIS2004: GZK and surroundings, Catania, Italy,
31.05.04. To appear in Nucl. Phys. B Proc. Supp
Ultrafast control of magnetic interactions via light-driven phonons
Resonant ultrafast excitation of infrared-active phonons is a powerful technique with which to control the electronic properties of materials that leads to remarkable phenomena such as the light-induced enhancement of superconductivity1,2, switching of ferroelectric polarization3,4 and ultrafast insulator-to-metal transitions5. Here, we show that light-driven phonons can be utilized to coherently manipulate macroscopic magnetic states. Intense mid-infrared electric field pulses tuned to resonance with a phonon mode of the archetypical antiferromagnet DyFeO3 induce ultrafast and long-living changes of the fundamental exchange interaction between rare-earth orbitals and transition metal spins. Non-thermal lattice control of the magnetic exchange, which defines the stability of the macroscopic magnetic state, allows us to perform picosecond coherent switching between competing antiferromagnetic and weakly ferromagnetic spin orders. Our discovery emphasizes the potential of resonant phonon excitation for the manipulation of ferroic order on ultrafast timescales6
Origin of the low-mass electron pair excess in light nucleus-nucleus collisions
We report measurements of electron pair production in elementary p+p and d+p
reactions at 1.25 GeV/u with the HADES spectrometer. For the first time, the
electron pairs were reconstructed for n+p reactions by detecting the proton
spectator from the deuteron breakup. We find that the yield of electron pairs
with invariant mass Me+e- > 0.15 GeV/c2 is about an order of magnitude larger
in n+p reactions as compared to p+p. A comparison to model calculations
demonstrates that the production mechanism is not sufficiently described yet.
The electron pair spectra measured in C+C reactions are compatible with a
superposition of elementary n+p and p+p collisions, leaving little room for
additional electron pair sources in such light collision systems.Comment: 11 pages, 2 figures, \usepackage{epsfig
Dilepton mass spectra in p+p collisions at sqrt(s)= 200 GeV and the contribution from open charm
The PHENIX experiement has measured the electron-positron pair mass spectrum
from 0 to 8 GeV/c^2 in p+p collisions at sqrt(s)=200 GeV. The contributions
from light meson decays to e^+e^- pairs have been determined based on
measurements of hadron production cross sections by PHENIX. They account for
nearly all e^+e^- pairs in the mass region below 1 GeV/c^2. The e^+e^- pair
yield remaining after subtracting these contributions is dominated by
semileptonic decays of charmed hadrons correlated through flavor conservation.
Using the spectral shape predicted by PYTHIA, we estimate the charm production
cross section to be 544 +/- 39(stat) +/- 142(syst) +/- 200(model) \mu b, which
is consistent with QCD calculations and measurements of single leptons by
PHENIX.Comment: 375 authors from 57 institutions, 18 pages, 4 figures, 2 tables.
Submitted to Physics Letters B. v2 fixes technical errors in matching authors
to institutions. Plain text data tables for the points plotted in figures for
this and previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Energy and system size dependence of \phi meson production in Cu+Cu and Au+Au collisions
We study the beam-energy and system-size dependence of \phi meson production
(using the hadronic decay mode \phi -- K+K-) by comparing the new results from
Cu+Cu collisions and previously reported Au+Au collisions at \sqrt{s_NN} = 62.4
and 200 GeV measured in the STAR experiment at RHIC. Data presented are from
mid-rapidity (|y|<0.5) for 0.4 < pT < 5 GeV/c. At a given beam energy, the
transverse momentum distributions for \phi mesons are observed to be similar in
yield and shape for Cu+Cu and Au+Au colliding systems with similar average
numbers of participating nucleons. The \phi meson yields in nucleus-nucleus
collisions, normalised by the average number of participating nucleons, are
found to be enhanced relative to those from p+p collisions with a different
trend compared to strange baryons. The enhancement for \phi mesons is observed
to be higher at \sqrt{s_NN} = 200 GeV compared to 62.4 GeV. These observations
for the produced \phi(s\bar{s}) mesons clearly suggest that, at these collision
energies, the source of enhancement of strange hadrons is related to the
formation of a dense partonic medium in high energy nucleus-nucleus collisions
and cannot be alone due to canonical suppression of their production in smaller
systems.Comment: 20 pages and 5 figure
Heavy quarkonium: progress, puzzles, and opportunities
A golden age for heavy quarkonium physics dawned a decade ago, initiated by
the confluence of exciting advances in quantum chromodynamics (QCD) and an
explosion of related experimental activity. The early years of this period were
chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in
2004, which presented a comprehensive review of the status of the field at that
time and provided specific recommendations for further progress. However, the
broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles
could only be partially anticipated. Since the release of the YR, the BESII
program concluded only to give birth to BESIII; the -factories and CLEO-c
flourished; quarkonium production and polarization measurements at HERA and the
Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the
deconfinement regime. All these experiments leave legacies of quality,
precision, and unsolved mysteries for quarkonium physics, and therefore beg for
continuing investigations. The plethora of newly-found quarkonium-like states
unleashed a flood of theoretical investigations into new forms of matter such
as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the
spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b},
and b\bar{c} bound states have been shown to validate some theoretical
approaches to QCD and highlight lack of quantitative success for others. The
intriguing details of quarkonium suppression in heavy-ion collisions that have
emerged from RHIC have elevated the importance of separating hot- and
cold-nuclear-matter effects in quark-gluon plasma studies. This review
systematically addresses all these matters and concludes by prioritizing
directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K.
Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D.
Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A.
Petrov, P. Robbe, A. Vair
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