511 research outputs found
The Petrophytic Steppes of the Urals: Diversity and Ecological Drivers
The diversity and main compositional patterns of the petrophytic steppes of the Urals were studied. Two questions were considered in detail: (i) How rich is the phytocoenotic diversity of the petrophytic steppes? and (ii) What kind of ecological drivers determine its differentiation? A dataset of 1,025 relevĂ©s was compiled,representing communities of different climatic and geological conditions. Using formalized classification (TWINSPAN algorithm), eight vegetation types on the petrophytic steppes were defined. DCA-ordination was used to determine the main ecological drivers (both climatic and edaphic) of plant communitiesâ diversity. Among them are mean annual temperature and precipitation, aridity, rockiness and local habitat moisture. The interaction of different ecological and geographical factors leads to high levels of floristic and coenotic diversity of vegetation in dry rocky habitats.
Keywords: petrophytic steppes, ecological drivers, ordination, Southern Ural
Tensor analyzing power Ayy in deuteron inclusive breakup at large Pt and spin structure of deuteron at short internucleonic distances
The Ayy data for deuteron inclusive breakup off hydrogen and carbon at a
deuteron momentum of 9.0 GeV/c and large Pt of emitted protons are presented.
The large values of Ayy independent of the target mass reflect the sensitivity
of the data to the deuteron spin structure. The data obtained at fixed and
plotted versus Pt clearly demonstrate the dependence of the deuteron spin
structure at short internucleonic distances on two variables. The data are
compared with the calculations using Paris, CD-Bonn and Karmanov's deuteron
wave functions.Comment: 4 pages, 2 figures, talk given at the SPIN2004 Conf., 10-16 Oct.
2004, Triest, Ital
Tensor Ayy and vector Ay analyzing powers in the H(d,d')X and ^{12}C(d,d')X reactons at initial deuteron momenta of 9 GeV/c in the region of baryonic resonances excitation
The angular dependence of the tensor Ayy and vector Ay analyzing powers in
the inelastic scattering of deuterons with a momentum of 9.0 GeV/c on hydrogen
and carbon have been measured. The range of measurements corresponds to the
baryonic resonance excitation with masses 2.2--2.6 GeV/c^2. The Ayy data being
in good agreement with the previous results demonstrate an approximate
scaling up to -1.5 (GeV/c)^2. The large values of A_y show a significant role
of the spin-dependent part of the elementary amplitude of the NN->NN* reaction.
The results of the experiment are compared with model predictions of the
plane-wave impulse approximation.Comment: 7 pages, 7 figures. submitted to Yad.Fi
Patterns of calcium oxalate monohydrate crystallization in complex biological systems
The paper presents the features of calcium oxalate crystallization in the presence of additives revealed through experimental modeling. The patterns of phase formation are shown for the Ca{2+} â C[2]O[4]{ 2â} â H[2]O and Ca{2+} â C[2]O[4]{2â} â PO[4]{3â} â H[2]O systems with the components and pH of the saline varying over a wide concentrations range. The effect of additives on crystallization of calcium oxalate monohydrate was investigated. It was found that the ionic strength and magnesium ions are inhibitors, and calcium oxalate and hydroxyapatite crystals are catalysts of calcium oxalate monohydrate crystallization. The basic calcium phosphate (apatite) was found to be most thermodynamically stable, which indicates its special role in kidney stone formation since it is found in virtually all stones
ĐĐŸĐČŃĐ” ĐČĐžĐŽŃ Đž ĐœĐ°ĐžĐ±ĐŸĐ»Đ”Đ” ĐžĐœŃĐ”ŃĐ”ŃĐœŃĐ” ĐœĐ°Ń ĐŸĐŽĐșĐž ĐŽĐ»Ń ŃĐ»ĐŸŃŃ ĐŁŃала Đž ĐżŃОлДгаŃŃĐžŃ ŃĐ”ŃŃĐžŃĐŸŃĐžĐč
The article provides information about rare and newly described species for the flora of the Urals and adjacent territories, namely: Astragalus saphronovae Kulikov, Atraphaxis decipiens Jaub. et Spach., Carex amgunensis F. Schmidt, Galium densiflorum Ledeb., Jovibarba globifera (L.) J. Parn., Najas minor All., Potamogeton nodosus Poir., Pseudorchis albida (L.) Ă. Löve et D. Löve, Salix myrsinites L., Veronica agrestis L. Essays include the information on the species ecology and short taxonomic notes. © 2021 Altai State University. All rights reserved.The work was supported by the state assignments: ĐĐĐĐ-Đ19-119031290052-1 âSosudistye rasteniia Evrazii: sistematika, flora, rastitelÊčnye resursyâ [âVascular plants of Eurasia: systematics, flora, plant resourcesâ], ĐĐĐĐ-Đ18-118011990151-7 âIzucheniye, sokhraneniye i rasshireniye bioraznoobraziya rasteniy v prirode i pri introduktsii na Yuzh nom Urale i Priuralyeâ [âStudy, conservation and expansion of plant biodiversity in nature and during introduction in the Southern Urals and the Cis- and Trans-Urals regionâ], AAAA-A17-117050400146-5 âOtsenka prostranstvennovremennoy izmenchivosti bioraznoobraziya i usloviy yego formirovaniya na Severe Zapadnoy Sibiri v svyazi s izmeneniyem klimata i osvoyeniyem neftegazovykh resursovâ [âAssessment of the spatio-temporal variability of biodiversity and the conditions for its formation in the north of Western Siberia in connection with climate change and the development of oil and gas resourcesâ], and by âProgrammoy povysheniya konkurentosposobnosti Uralskogo federalnogo universitetaâ [âThe program for improving the competitiveness of the Ural Federal Universityâ] (the decree no. 211 of the Government of the Russian Federation, contract no. 02.A03.21.0006)
Journal Staff
We present the first measurements of the differential cross section d sigma/dp(T)(gamma) for the production of an isolated photon in association with at least two b-quark jets. The measurements consider photons with rapidities vertical bar y(gamma)vertical bar < 1.0 and transverse momenta 30 < p(T)(gamma) < 200 GeV. The b-quark jets are required to have p(T)(jet) > 15 GeVand vertical bar y(jet)vertical bar < 1.5. The ratio of differential production cross sections for gamma + 2 b-jets to gamma + b-jet as a function of p(T)(gamma) is also presented. The results are based on the proton-antiproton collision data at root s = 1.96 TeV collected with the D0 detector at the Fermilab Tevatron Collider. The measured cross sections and their ratios are compared to the next- to- leading order perturbative QCD calculations as well as predictions based on the k(T)- factorization approach and those from the sherpa and pythia Monte Carlo event generators
Precise measurement of the top quark mass in the dilepton channel at D0
We measure the top quark mass (mt) in ppbar collisions at a center of mass
energy of 1.96 TeV using dilepton ttbar->W+bW-bbar->l+nubl-nubarbbar events,
where l denotes an electron, a muon, or a tau that decays leptonically. The
data correspond to an integrated luminosity of 5.4 fb-1 collected with the D0
detector at the Fermilab Tevatron Collider. We obtain mt = 174.0 +- 1.8(stat)
+- 2.4(syst) GeV, which is in agreement with the current world average mt =
173.3 +- 1.1 GeV. This is currently the most precise measurement of mt in the
dilepton channel.Comment: 7 pages, 4 figure
A search for charged massive long-lived particles
We report on a search for charged massive long-lived particles (CMLLPs),
based on 5.2 fb of integrated luminosity collected with the D0 detector
at the Fermilab Tevatron collider. We search for events in which one
or more particles are reconstructed as muons but have speed and ionization
energy loss inconsistent with muons produced in beam collisions.
CMLLPs are predicted in several theories of physics beyond the standard model.
We exclude pair-produced long-lived gaugino-like charginos below 267 GeV and
higgsino-like charginos below 217 GeV at 95% C.L., as well as long-lived scalar
top quarks with mass below 285 GeV.Comment: submitted to Phys. Rev. Letter
Direct measurement of the mass difference between top and antitop quarks
We present a direct measurement of the mass difference between top and
antitop quarks (dm) in lepton+jets top-antitop final states using the "matrix
element" method. The purity of the lepton+jets sample is enhanced for
top-antitop events by identifying at least one of the jet as originating from a
b quark. The analyzed data correspond to 3.6 fb-1 of proton-antiproton
collisions at 1.96 TeV acquired by D0 in Run II of the Fermilab Tevatron
Collider. The combination of the e+jets and mu+jets channels yields dm = 0.8
+/- 1.8 (stat) +/- 0.5 (syst) GeV, which is in agreement with the standard
model expectation of no mass difference.Comment: submitted to Phys. Rev.
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