196 research outputs found
Population synthesis of DA white dwarfs: constraints on soft X-ray spectra evolution
Extending the population synthesis method to isolated young cooling white
dwarfs we are able to confront our model assumptions with observations made in
ROSAT All-Sky Survey (Fleming et al., 1996). This allows us to check model
parameters such as evolution of spectra and separation of heavy elements in DA
WD envelopes. It seems like X-ray spectrum temperature of these objects is
given by the formula T_{X-ray} = min(T_eff, T_max). We have obtained DA WD's
birth rate and upper limit of the X-ray spectrum temperature: DA birth rate in cubic parsec per year and T_max = 41000 K. These values
are in good correspondence with values obtained by other authors (Liebert et
al., 2004; Wolff et al., 1996). From this fact we also conclude that our
population synthesis method is applicable to the population of close-by
isolated cooling white dwarfs as well as to the population of the isolated
cooling neutron stars.Comment: 4 pages, 3 figures, conference "European White Dwarf Workshop, 2010",
Tubingen, German
Composite Ceramics Based on Garnet-type Oxide Y2.5Nd0.5Al5O12 and Silicon Carbide. Preparation. Properties
We have obtained powders of garnet-type complex oxide Y2.5Nd0.5Al5O12 – x vol.% SiC (x = 0, 10, 20) using wet chemistry techniques. The ceramics based on the studying compounds were sintered using Spark Plasma Sintering (SPS) (
Air ions induced aerosol sensing by eye-safe LIDAR
Low concentrations aerosols quantification is rather challenging for LIDAR
instruments due to eye-safety restrictions so high energy pulses cannot be
utilized to improve the sensitivity. Highly sensitive but eye-save LIDAR has
been developed for the quantification of the water droplet aerosol which was
induced by air ions. Few days sensing of aerosols in closed tunnel revealed a
strong correlation between air optical transparency (LIDAR measurements) and
concentrations of positive/negative ions (ion counter Sapphir 3-M). The
correlation coefficient was observed to be almost unity for the air
transparency signal and air ions unipolarity coefficient. High sensitivity of
the water droplet aerosol quantification makes the developed eye-safe LIDAR a
perspective instrument for space resolved measurements of the air ions
distribution. Space and time resolved measurements of air ions exhalation can
be a new instrument for tectonic activity study including new earthquake
forecasting indicators search
Investigation of the effect of the grain sizes on the dynamic strength of the fine-grained alumina ceramics obtained by Spark Plasma Sintering
The results of dynamic strength tests of the alumina ceramics with various
grain sizes are presented. The ceramics were obtained by Spark Plasma Sintering
(SPS) of industrial submicron and fine Al2O3 powders. The heating up was
performed with the rate of 10 oC/min; the grain sizes in the ceramics was
controlled by varying the SPS temperature and the heating rate as well as by
varying the initial sizes of the Al2O3 particles in the powders. The ceramics
had a high density (over 98%) and a uniform fine-grained microstructure (the
mean grain sizes varied from 0.8 to 13.4 mkm). The dynamic compressing tests
were carried out by modified Kolsky method with using split Hopkinson pressure
bar. The tests were performed at room temperature using a 20-mm PG-20 gas gun
with the strain rate of ~10^3 s-1. The dependence of the dynamic ultimate
strength of alumina on the grain size was found for the first time to have a
non-monotonous character (with a maximum). The maximum value of the dynamic
ultimate compression strength (SY = 1060 MPa) was provided at the mean grain
size of ~2.9-3 mkm. The reduction of SY for alumina in the range of submicron
grain sizes was shown to originate from the reduction of the relative density
of the ceramics sintered at lower SPS temperatures.Comment: 16 pages, 1 table, 6 figures, 28 reference
Tungstate Based Ceramics Obtained By Spark Plasma Sintering Method – Possible Material for Consolidation of Radioactive Wastes’ Components
The Spark Plasma Sintering method was used to produce high-density ceramics from tungstates SrWO4 and NaNd(WO4)2 with scheelite structure. These compounds are proposed as possible matrices for the consolidation of radwaste components. Powder samples were obtained by coprecipitation method and studied by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). After sintering, the samples retained their phase identity (scheelite structure). The total duration of sintering was ∼ 13-15 min, the relative density was reached ∼ 92, 99%.
Keywords: Tungstates, RW, Spark Plasma Sintering, high density, microstructur
Diagnosis and treatment of muscle pain according to Tipaldos (literature review)
This review contents the information on the theory of the structure and mechanisms of damage to the body fascial system, proposed by American osteopath S. Tipaldos and named by him the Fascial Distortion Model (FDM), as well as on the original method of diagnosis and treatment of muscle pain syndromes associated with fascial damage (distortion). The author describes classifications of connective tissue and fascial structures, created by S. Tipaldos, which are based on anatomical and functional features that determine the role of each type of fascia in compensating for various types of external influences. The conditions, mechanisms of formation and characteristics of six types of fascial lesions identified by S. Tipaldos are considered in detail: triggerband, herniated triggerpoint, continuum distortion, folding distortion, cylinder distortion, tectonic fixation. All elements of the fascial distortions diagnosis are discussed in detail, including the specification of complaints (characteristics of pain syndrome), anamnesis (history of the pain onset and its development) and an objective examination (the actual diagnostic techniques). At the same time, the special role of the patient’s description of his own painful sensations with the help of specific gestures and movements, called «body language», is emphasized. The principles and some methods of therapeutic effects used in FDM-therapy, indications and contraindications for the use of the considered manual techniques, possible side reactions that may occur during manipulation or after a session of FDMtherapy are presented. Particular attention is paid to the evidence base of FDM therapy effectiveness in comparison with traditional methods of myofascial pain syndromes manual treatment: the results of controlled studies by foreign authors, confirming the new technique effectiveness in the treatment of certain muscle algic phenomena types, are considered
Investigation of the microstructure of the fine-grained YPO:Gd ceramics with xenotime structure after Xe irradiation
The paper reports on the preparation of xenotime-structured ceramics by the
Spark Plasma Sintering (SPS) method. Phosphates YGdPO
(YPO:Gd) were obtained by the sol-gel method. The synthesized nanopowders
are collected in large agglomerates 10-50 mkm in size. Ceramics has a
fine-grained microstructure and a high relative density (98.67%). The total
time of the SPS process was approximately 18 min. High-density sintered
ceramics YPO:Gd with a xenotime structure were irradiated with Xe
ions (E = 167 MeV) to fluences of - cm.
Complete amorphization at maximum fluence was not achieved. As the fluence
increases, an insignificant increase in the depth of the amorphous layer is
observed. According to the results of grazing incidence XRD (GIXRD), with an
increase in fluence from - cm, an
increase in the volume fraction of the amorphous structure from 20 to 70% is
observed. The intensity of XRD peak 200 YPO:Gd after recovery annealing
(700C, 18 h) reached a value of ~80% of the initial intensity I0.Comment: 16 pages, 10 figure
Finite-sample and asymptotic sign-based tests for parameters of non-linear quantile regression with Markov noise
One of the most noticeable features of sign-based statistical procedures is an opportunity to build an exact test for simple hypothesis testing of parameters in a regression model. In this article, we expanded a sing-based approach to the nonlinear case with dependent noise. The examined model is a multi-quantile regression, which makes it possible to test hypothesis not only of regression parameters, but of noise parameters as well
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