466 research outputs found
Catalog of Nearby Isolated Galaxies in the Volume z<0.01
We present a catalog of 520 most isolated nearby galaxies with radial
velocities V_LG<3500 km/s covering the entire sky. This population of "space
orphans" makes up 4.8% among 10900 galaxies with measured radial velocities. We
describe the isolation criterion used to select our sample, called the "Local
Orphan Galaxies" (LOG), and discuss their basic optical and HI properties. A
half of the LOG catalog is occupied by the Sdm, Im and Ir morphological type
galaxies without a bulge. The median ratio M_gas/M_star in the LOG galaxies
exceeds 1. The distribution of the catalog galaxies on the sky looks uniform
with some signatures of a weak clustering on the scale of about 0.5 Mpc. The
LOG galaxies are located in the regions where the mean local density of matter
is approximately 50 times lower than the mean global density. We indicate a
number of LOG galaxies with distorted structures, which may be the consequence
of interaction of isolated galaxies with massive dark objects
Оценка свойств костнозамещающих материалов на основе полиэтиленгликоль диакрилата и октакальциевого фосфата на модели монокортикального диафизарного дефекта бедренной кости крысы: экспериментальное исследование
Background. The problem of bone defects replacement is relevant nowadays, that is why many scientists create new synthetic bone substitutes, but the ideal material has not been found so far.
The aims of the study: 1) to determine the suitability of the monocortical defect model in the rat femur diaphysis with additional prophylactic reinforcement with a bone plate for assessing the biological properties of implanted materials using the commercially available ChronOS material as an example; 2) to assess of the osteoconductive properties of composite materials based on poly(ethylene glycol)diacrylate and octacalcium phosphate with architecture Kelvin and gyroid types on the developed model.
Methods. A prospective study, level of evidence II. A monocortical defect of the rat femoral diaphysis (length 7 mm) was produced under anaesthesia in aseptic conditions and fixed with a polyetheretherketone plate and six titanium screws. In the control group, the defect was left empty. In other groups, blocks of one of three materials were implanted сhronOS and composites of poly(ethylene glycol)diacrylate and octacalcium phosphate with 3D-printed Kelvin and gyroid architectures. After 3 and 6 weeks, the rats were sacrificed, and histological examination of the defect zone was performed. The amount of newly formed bone tissue was histometricly assessed, followed by statistical processing of the results.
Results. All rats have reached the planned endpoint, and there were no infectious complications or loss of fixation. Histological examination of the defect zone revealed minimal bone growth in the Control group, rather slow bone formation in the Gyroid group, and statistically significantly more pronounced bone formation in the pores of the materials in the Kelvin and Chronos groups.
Conclusions. Bone defect in this model was not spontaneously filled with bone tissue and allowed us to study the biological properties of bone substitutes (the ability to biodegrade and osteoconductive properties). The osteoconductive properties of a composite material based on poly(ethylene glycol)diacrylate and octacalcium phosphate with a Kelvin architecture are higher than with a gyroid architecture and are comparable to that of the сhronOS.Актуальность. Проблема замещения дефектов кости актуальна в настоящее время, постоянно ведутся поиски новых синтетических костнозамещающих материалов, однако идеальный материал не найден до сих пор.
Цели исследования: 1) определение пригодности модели монокортикального дефекта диафиза бедренной кости крысы с дополнительным профилактическим армированием при помощи накостной пластины для оценки биологических свойств имплантируемых материалов на примере коммерчески доступного материала сhronOS; 2) оценка остеокондуктивных свойств композитных материалов на основе полиэтиленгликоль диакрилата и октакальциевого фосфата с архитектурой Кельвина и типа гироид на разработанной модели.
Материал и методы. Монокортикальный дефект диафиза бедренной кости крыс размером 7 мм в длину производили под наркозом в асептических условиях операционной и фиксировали полиэфирэфиркетоновой пластиной и шестью титановыми винтами. Крыс распределяли случайным образом на четыре группы по 12 особей в каждой. В группе Контроль у животных костный дефект не заполняли. У животных в группе Хронос дефект заполняли подготовленным материалом chronOS в виде полуцилиндрического блока, в группе Кельвин исследуемым материалом с архитектурой Кельвина, в группе Гироид исследуемым материалом с архитектурой типа гироид. Через 3 и 6 нед. крыс выводили из эксперимента и производили гистологическое исследование зоны дефекта. Затем выполняли гистометрическую оценку количества новообразованной костной ткани с последующей статистической обработкой результатов.
Результаты. В ходе эксперимента все животные достигли планируемой конечной точки, инфекционные осложнения и потеря фиксации зафиксированы не были. При гистологическом исследовании зоны дефекта выявлен минимальный рост кости в группе Контроль, достаточно медленное образование кости в материале группы Гироид и статистически значимо более выраженное образование костной ткани в порах материалов в группах Кельвин и Хронос.
Заключение. Разработанная модель дефекта кости спонтанно не заполняется костной тканью и позволяет проводить изучение биологических свойств костнопластических материалов (способность к биодеградации и остеокондуктивные свойства). Остеокондуктивные свойства композитного материала на основе полиэтиленгликоль диакрилата и октакальциевого фосфата с архитектурой Кельвина выше, чем с архитектурой типа гироид, и сопоставимы с таковыми у материала сhronOS
High Precision Mass Measurements in and Families Revisited
High precision mass measurements in and families performed
in 1980-1984 at the VEPP-4 collider with OLYA and MD-1 detectors are revisited.
The corrections for the new value of the electron mass are presented. The
effect of the updated radiative corrections has been calculated for the
and mass measurements.Comment: 5 pages, 1 table, submitted to Phys. Lett.
Measurement of and between 3.12 and 3.72 GeV at the KEDR detector
Using the KEDR detector at the VEPP-4M collider, we have measured
the values of and at seven points of the center-of-mass
energy between 3.12 and 3.72 GeV. The total achieved accuracy is about or
better than at most of energy points with a systematic uncertainty of
about . At the moment it is the most accurate measurement of in
this energy range
New precise determination of the \tau lepton mass at KEDR detector
The status of the experiment on the precise lepton mass measurement
running at the VEPP-4M collider with the KEDR detector is reported. The mass
value is evaluated from the cross section behaviour around the
production threshold. The preliminary result based on 6.7 pb of data is
MeV. Using 0.8 pb of data
collected at the peak the preliminary result is also obtained:
eV.Comment: 6 pages, 8 figures; The 9th International Workshop on Tau-Lepton
Physics, Tau0
Measurement of \Gamma_{ee}(J/\psi)*Br(J/\psi->e^+e^-) and \Gamma_{ee}(J/\psi)*Br(J/\psi->\mu^+\mu^-)
The products of the electron width of the J/\psi meson and the branching
fraction of its decays to the lepton pairs were measured using data from the
KEDR experiment at the VEPP-4M electron-positron collider. The results are
\Gamma_{ee}(J/\psi)*Br(J/\psi->e^+e^-)=(0.3323\pm0.0064\pm0.0048) keV,
\Gamma_{ee}(J/\psi)*Br(J/\psi->\mu^+\mu^-)=(0.3318\pm0.0052\pm0.0063) keV.
Their combinations
\Gamma_{ee}\times(\Gamma_{ee}+\Gamma_{\mu\mu})/\Gamma=(0.6641\pm0.0082\pm0.0100)
keV,
\Gamma_{ee}/\Gamma_{\mu\mu}=1.002\pm0.021\pm0.013 can be used to improve
theaccuracy of the leptonic and full widths and test leptonic universality.
Assuming e\mu universality and using the world average value of the lepton
branching fraction, we also determine the leptonic \Gamma_{ll}=5.59\pm0.12 keV
and total \Gamma=94.1\pm2.7 keV widths of the J/\psi meson.Comment: 7 pages, 6 figure
Search for narrow resonances in e+ e- annihilation between 1.85 and 3.1 GeV with the KEDR Detector
We report results of a search for narrow resonances in e+ e- annihilation at
center-of-mass energies between 1.85 and 3.1 GeV performed with the KEDR
detector at the VEPP-4M e+ e- collider. The upper limit on the leptonic width
of a narrow resonance Gamma(R -> ee) Br(R -> hadr) < 120 eV has been obtained
(at 90 % C.L.)
Measurement of main parameters of the \psi(2S) resonance
A high-precision determination of the main parameters of the \psi(2S)
resonance has been performed with the KEDR detector at the VEPP-4M e^{+}e^{-}
collider in three scans of the \psi(2S) -- \psi(3770) energy range. Fitting the
energy dependence of the multihadron cross section in the vicinity of the
\psi(2S) we obtained the mass value
M = 3686.114 +- 0.007 +- 0.011 ^{+0.002}_{-0.012} MeV and the product of the
electron partial width by the branching fraction into hadrons \Gamma_{ee}*B_{h}
= 2.233 +- 0.015 +- 0.037 +- 0.020 keV.
The third error quoted is an estimate of the model dependence of the result
due to assumptions on the interference effects in the cross section of the
single-photon e^{+}e^{-} annihilation to hadrons explicitly considered in this
work.
Implicitly, the same assumptions were employed to obtain the charmonium
leptonic width and the absolute branching fractions in many experiments.
Using the result presented and the world average values of the electron and
hadron branching fractions, one obtains the electron partial width and the
total width of the \psi(2S):
\Gamma_{ee} =2.282 +- 0.015 +- 0.038 +- 0.021 keV,
\Gamma = 296 +- 2 +- 8 +- 3 keV.
These results are consistent with and more than two times more precise than
any of the previous experiments
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
Measurements of inclusive jet suppression in heavy ion collisions at the LHC
provide direct sensitivity to the physics of jet quenching. In a sample of
lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated
luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with
a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the
transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the
anti-kt algorithm with values for the distance parameter that determines the
nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of
the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp.
Jet production is found to be suppressed by approximately a factor of two in
the 10% most central collisions relative to peripheral collisions. Rcp varies
smoothly with centrality as characterized by the number of participating
nucleons. The observed suppression is only weakly dependent on jet radius and
transverse momentum. These results provide the first direct measurement of
inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables,
submitted to Physics Letters B. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
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