150 research outputs found
SCIENTIFIC COMMUNICATION SKILLS ARE IMPORTANT FOR ALL CLINICIANS
The author discusses the need for scientific communication, knowledge about impact indicators and other criteria for assessing scientific publications, as well as current approaches to choosing journals to publish the results of researches. The high level of Russian rheumatology and the quality of articles published in the journal «Nauchno-Prakticheskaya Revmatologiya» (Rheumatology Science and Practice) are mentioned
Isolation of Peaks in TDS Spectra of Deuterium from Ion Irradiated Tungsten
AbstractInteraction of deuterium with radiation defects in tungsten was studied by means of thermal desorption spectroscopy. The displacement damage in a recrystallized tungsten foil was produced by irradiation with 10 keV/D ions to the fluences in the range of 3–8×1019 D/m2 at room temperature. The resulted thermal desorption spectra consisted of three wide overlapping peaks. It was shown that annealing of the damaged sample at 550 K and subsequent implantation with 0.67 keV/D ions allows to isolate the peak corresponding to deuterium release from vacancies
Exclusive and semi-inclusive strangeness and charm production in and reactions
Using the Quark-Gluon Strings Model (QGSM) combined with Regge phenomenology
we consider the reactions and which are dominated by the contributions of the and
Regge trajectories, respectively. The spin structure of the amplitudes is
described by introducing Reggeized Born terms. It is found that the existing
data for the reaction are in reasonable agreement
with the model predictions. To describe the absolute values of the cross
sections it is necessary to introduce also suppression factors which can be
related to absorption corrections. Furthermore, assuming the SU(4) symmetry to
hold for Regge residues and the universality of absorption corrections we
calculate the cross section of the reaction .
Employing the latter results from reactions we then estimate the
contributions of the pion exchange mechanism to the cross sections of the
reactions and and compare them
with the contributions of the and exchanges. We find that the
reactions are dominated not by pion exchange but by and exchanges,
respectively. Moreover, assuming the SU(4) symmetry to hold approximately for
the coupling constants = we analyze also
the production of leading hyperons in the reaction . It is shown that the non-perturbative mechanism should give an
essential contribution to the yield for .Comment: 3 pages, LaTeX, 4 postscript figures; contribution to QNP2002,
Juelich, June 10-14, 200
Laser-based Diagnostics for Use in Ex-situ Lithium Co-deposit Analysis
Laser-induced breakdown spectroscopy (LIBS) and time of flight (TOF) mass spectrometry of laser-produced ions were tested for ex-situ analysis of lithium co-deposited layers produced by plasma deposition. It was found that LIBS provides an adequate way to observe and measure lithium content in thin co-deposited layers of about 1 µm thickness. TOF mass spectrometry data of the same layers was compared with LIBS. TOF mass spectrometry provided a better resolution; however, the simplicity of LIBS setup and the rate of measurement (less than one minute per measurement) makes it more attractive. Argon was observed in the co-deposited layers, indicating that it, and likely other inert gases, can remain trapped in lithium layers even after a prolonged exposure to and chemical reaction with atmospheric air
Experimental study of weak antilocalization effect in a high mobility InGaAs/InP quantum well
The magnetoresistance associated with quantum interference corrections in a
high mobility, gated InGaAs/InP quantum well structure is studied as a function
of temperature, gate voltage, and angle of the tilted magnetic field.
Particular attention is paid to the experimental extraction of phase-breaking
and spin-orbit scattering times when weak anti- localization effects are
prominent. Compared with metals and low mobility semiconductors the
characteristic magnetic field in high mobility
samples is very small and the experimental dependencies of the interference
effects extend to fields several hundreds of times larger. Fitting experimental
results under these conditions therefore requires theories valid for arbitrary
magnetic field. It was found, however, that such a theory was unable to fit the
experimental data without introducing an extra, empirical, scale factor of
about 2. Measurements in tilted magnetic fields and as a function of
temperature established that both the weak localization and the weak
anti-localization effects have the same, orbital origin. Fits to the data
confirmed that the width of the low field feature, whether a weak localization
or a weak anti-localization peak, is determined by the phase-breaking time and
also established that the universal (negative) magnetoresistance observed in
the high field limit is associated with a temperature independent spin-orbit
scattering time.Comment: 13 pages including 10 figure
Содержание окиси азота в слюне и легочная гипертензия у больных с различной степенью тяжести бронхиальной астмы
The involvement of nitric oxide in the formation of bronchial hyperresponsiveness and pulmonary hypertension in bronchial asthma was studied. Shifts of nitric oxide were assessed by measuring nitric anion content in saliva using Griess reaction in 67 patients with non-atopic bronchial asthma. We assessed a pulmonary hypertension level and a condition of left and right ventricles by echocardiography.It was shown that nitrite level in saliva depends on severity of airway limitation. Significant increase in nitrite content was revealed in mild bronchial asthma patients, especially during exacerbation. However, nitrite level in patients with status asthmaticus was significantly decreased. Based on data obtained we have suggested that changes in saliva nitric oxide reflect adaptive capacities of upper and lower airways and cardiovascular system in asthmatic patients with pulmonary hypertension. Nitric oxide produced in upper respiratory tract and oral cavity and self-inhaled thought to provide remarkable improvement in asthma and pulmonary hypertension course.The investigation findings allow us to conclude that measurement of nitrite saliva level in bronchial asthma patients could be used for diagnostic purpose and its results could constitute an alternative approach to antiasthmatic and hypotensive treatment.Показано, что сдвиги в содержании нитрита в слюне больных бронхиальной астмой связаны с выраженностью бронхообструкции и изменениями в сердечно-сосудистой системе в условиях гипоксического стресса и формирования легочной гипертензии. Рекомендовано определение уровня нитрита в слюне для оценки выраженности бронхообструкции и корригирования схем противовоспалительной и противоастматической терапии при бронхиальной астме
Multi-messenger characterization of Mrk 501 during historically low X-ray and -ray activity
We study the broadband emission of Mrk 501 using multi-wavelength
observations from 2017 to 2020 performed with a multitude of instruments,
involving, among others, MAGIC, Fermi-LAT, NuSTAR, Swift, GASP-WEBT, and OVRO.
Mrk 501 showed an extremely low broadband activity, which may help to unravel
its baseline emission. Nonetheless, significant flux variations are detected at
all wavebands, with the highest occurring at X-rays and very-high-energy (VHE)
-rays. A significant correlation (3) between X-rays and VHE
-rays is measured, supporting leptonic scenarios to explain the
variable parts of the emission, also during low activity. This is further
supported when we extend our data from 2008 to 2020, and identify, for the
first time, significant correlations between Swift-XRT and Fermi-LAT. We
additionally find correlations between high-energy -rays and radio,
with the radio lagging by more than 100 days, placing the -ray emission
zone upstream of the radio-bright regions in the jet. Furthermore, Mrk 501
showed a historically low activity in X-rays and VHE -rays from
mid-2017 to mid-2019 with a stable VHE flux (0.2 TeV) of 5% the emission of
the Crab Nebula. The broadband spectral energy distribution (SED) of this
2-year-long low-state, the potential baseline emission of Mrk 501, can be
characterized with one-zone leptonic models, and with (lepto)-hadronic models
fulfilling neutrino flux constraints from IceCube. We explore the time
evolution of the SED towards the low-state, revealing that the stable baseline
emission may be ascribed to a standing shock, and the variable emission to an
additional expanding or traveling shock.Comment: 56 pages, 30 figures, 14 tables, submitted. Corresponding authors are
L. Heckmann, D. Paneque, S. Gasparyan, M. Cerruti, and N. Sahakya
Searching for VHE gamma-ray emission associated with IceCube neutrino alerts using FACT, H.E.S.S., MAGIC, and VERITAS
The realtime follow-up of neutrino events is a promising approach to searchfor astrophysical neutrino sources. It has so far provided compelling evidencefor a neutrino point source: the flaring gamma-ray blazar TXS 0506+056 observedin coincidence with the high-energy neutrino IceCube-170922A detected byIceCube. The detection of very-high-energy gamma rays (VHE, ) from this source helped establish the coincidence andconstrained the modeling of the blazar emission at the time of the IceCubeevent. The four major imaging atmospheric Cherenkov telescope arrays (IACTs) -FACT, H.E.S.S., MAGIC, and VERITAS - operate an active follow-up program oftarget-of-opportunity observations of neutrino alerts sent by IceCube. Thisprogram has two main components. One are the observations of known gamma-raysources around which a cluster of candidate neutrino events has been identifiedby IceCube (Gamma-ray Follow-Up, GFU). Second one is the follow-up of singlehigh-energy neutrino candidate events of potential astrophysical origin such asIceCube-170922A. GFU has been recently upgraded by IceCube in collaborationwith the IACT groups. We present here recent results from the IACT follow-upprograms of IceCube neutrino alerts and a description of the upgraded IceCubeGFU system.<br
Observation of a sudden cessation of a very-high-energy gamma-ray flare in PKS 1510-089 with H.E.S.S. and MAGIC in May 2016
The flat spectrum radio quasar (FSRQ) PKS 1510-089 is known for its complex multiwavelength behavior, and is one of only a few FSRQs detected at very high energy (VHE, E >100 GeV) -rays. VHE -ray observations with H.E.S.S. and MAGIC during late May and early June 2016 resulted in the detection of an unprecedented flare, which reveals for the first time VHE -ray intranight variability in this source. While a common variability timescale of 1.5 hr is found, there is a significant deviation near the end of the flare with a timescale of ∼ 20 min marking the cessation of the event. The peak flux is nearly two orders of magnitude above the low-level emission. For the first time, curvature is detected in the VHE -ray spectrum of PKS 1510-089, which is fully explained through absorption by the extragalactic background light. Optical R-band observations with ATOM reveal a counterpart of the -ray flare, even though the detailed flux evolution differs from the VHE lightcurve. Interestingly, a steep flux decrease is observed at the same time as the cessation of the VHE flare. In the high energy (HE, E >100 MeV) -ray band only a moderate flux increase is observed with Fermi-LAT, while the HE -ray spectrum significantly hardens up to a photon index of 1.6. A search for broad-line region (BLR) absorption features in the -ray spectrum indicates that the emission region is located outside of the BLR. Radio VLBI observations reveal a fast moving knot interacting with a standing jet feature around the time of the flare. As the standing feature is located ∼ 50 pc from the black hole, the emission region of the flare may have been located at a significant distance from the black hole. If this correlation is indeed true, VHE rays have been produced far down the jet where turbulent plasma crosses a standing shock.Accepted manuscrip
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