Context. One of the difficulties with performing polarization analysis is that the mean polarization fraction of sub-divided data sets is larger than the polarization fraction for the integrated ...measurement. The resulting bias is one of the properties of the generating distribution discussed in this work. The limitations of Gaussian approximations in standard analysis based on Stokes parameters for estimating polarization parameters and their uncertainties are explored by comparing with a Bayesian analysis. The effect of uncertainty on the modulation factor is also shown, since it can have a large impact on the performance of gamma-ray burst polarimeters. Results are related to the minimum detectable polarization (MDP), a common figure of merit, making them easily applicable to any X-ray polarimeter. Aims. The aim of this work is to quantify the systematic errors induced on polarization parameters and their uncertainties when using Gaussian approximations and to show when such effects are non-negligible. Methods. The probability density function is used to deduce the properties of reconstructed polarization parameters. The reconstructed polarization parameters are used as sufficient statistics for finding a simple form of the likelihood. Bayes theorem is used to derive the posterior and to include nuisance parameters. Results. The systematic errors originating from Gaussian approximations as a function of instrument sensitivity are quantified here. Different signal-to-background scenarios are considered making the analysis relevant for a large variety of observations. Additionally, the change of posterior shape and instrument performance MDP due to uncertainties on the polarimeteric response of the instrument is shown.
Strong magnetic fields, synchrotron emission, and Compton scattering are omnipresent in compact celestial X-ray sources. Emissions in the X-ray energy band are consequently expected to be linearly ...polarized. X-ray polarimetry provides a unique diagnostic to study the location and fundamental mechanisms behind emission processes. The polarization of emissions from a bright celestial X-ray source, the Crab, is reported here for the first time in the hard X-ray band (~20-160 keV). The Crab is a complex system consisting of a central pulsar, a diffuse pulsar wind nebula, as well as structures in the inner nebula including a jet and torus. Measurements are made by a purpose-built and calibrated polarimeter, PoGO+. The polarization vector is found to be aligned with the spin axis of the pulsar for a polarization fraction, PF = (20.9 ± 5.0)%. This is higher than that of the optical diffuse nebula, implying a more compact emission site, though not as compact as, e.g., the synchrotron knot. Contrary to measurements at higher energies, no significant temporal evolution of phase-integrated polarisation parameters is observed. The polarization parameters for the pulsar itself are measured for the first time in the X-ray energy band and are consistent with observations at optical wavelengths.
The proposed paper is a study of resource nationalism. Resource nationalism appeared in Mongolia in the post-Socialist period. In this paper, we understand resource nationalism as a wide spectrum of ...strategies domestic elites employ in order to increase their control of natural resources - definition by Paul Domjan and Matt Stone. After an analysis of legal materials, mass media articles and political rhetoric, the author of this paper concludes that the sources of resource nationalism should be searched in the texts that date back to the Socialist era. Also, the sources of resource nationalism can be found in the ideas about justice of those times. The idea that natural resources belong to the people has been fixed in mass opinion, while contemporary nationalists justify this idea from the standpoint of “blood and soil”. That creates serious problems for Mongolia, a country with resource economy. The matter is that economic growth driven with foreign investments has caused a deep social stratification. In its turn, social stratification gave birth to a social demand for fair profit distribution from natural resource extraction. In the political sphere, this social demand quickly received a reaction - in the form of resource nationalism rhetoric. In the paper, we notice that resource nationalism in Mongolia has not been formed as a vivid legal or political doctrine. Today, it is a set of populist rhetoric of current interest which are used both for lobbying future political decisions in mining and for legitimizing the decisions already made.
A comprehensive analysis of the composition of the alluvium of the river with active gas–hydrothermal occurrences has been carried out for the first time. Common features in the lower and middle ...reaches of the Geysernaya River include poor roundness of boulders and pebbles (grades 1–2), poor grading of alluvium fine-clastic components, abundant rock fragments, and mineral intergrowths even in the fine-sand fraction. All this information is indicative of weak sediment disintegration and a high proportion of slope material in sediments, including that redeposited by mudflows. High contents of smectite–zeolite and other newly formed (secondary) mineral aggregates (up to 70% of the light fraction of 0.1–0.25 mm in size) and altered rock fragments (up to 70–80% in the pebble fraction of alluvium) make it possible to suggest a great effect of gas–hydrothermal activity on the processing of river-eroded rocks, as well as the secondary weathering of the alluvium within the thermal fields. The riverbed deposition is fragmentary and predominant in the areas of (1) the active slope material inflow (temporary dams), (2) flattening of the longitudinal profile in dammed reservoirs, and (3) mudflow material removal. Two dammed reservoirs formed over the past 15 years, as well as fine-sand layers in the low-terrace sediments are indicative of the fact that the Geysernaya River valley is characterized by the periodic formation of such short-lived basins. The deposition conditions of the fine-sand alluvium are different in sections of a single-branch channel and within dammed reservoirs and affect the ratio of the principal minerals of the heavy fraction. Abundant well-rounded gravel and coarse sand and their weathered appearance make it possible to assume that, along with the processing of large volumes of incoming slope and mudflow material, the Geysernaya River continues to cut in and to erode ancient fluvial sediments probably of the pre-caldera stage.
The probability of a large early release is one of the safety indicators that reflects the risk of fatalities during an accident at a nuclear power plant. Despite the fact that this indicator is very ...important, it is not defined in the federal rules and regulations of the Russian Federation. The article analyzes the worldwide experience related to determining criteria for large early release taking into account the statistical data of the specific country under consideration. Based on the analysis, the definition of a large early accidental release and the criteria for its achievement are formulated taking into account measures to protect the population living within the protective action planning zone (PAPZ), and an approach for their definition is proposed. A conclusion has been made about the sustainable nature of the goals identified using the NRC approach. A critical analysis of the safety indicators established worldwide allowed for the conclusion that it is necessary to improve the methodology for assessing the safety goals taking into account the specifics of NPP design, regional characteristics, phases of accident progression and other factors. The paper outlines the proposed approaches to determining high-level safety goals based on probabilistic targets – quantitative values for probabilistic health objectives (PHO) designated as PHO1 and PHO2 for the Russian Federation. A definition of a “large early release” is formulated and criteria for its achievement are proposed taking into account measures to protect the population living within the PAPZ. Thus, when assessing the degree, to which these goals are achieved in practice, it is proposed to take into account not only the likelihood of a large release during an accident at a nuclear power plant, but also measures aimed at protecting the population, in particular, evacuation. In this case, early deaths occur only when the population is not evacuated before the critical health dose loads from the release are reached.
Polarimetric observations of celestial sources in the hard X-ray band stand to provide new information on emission mechanisms and source geometries. PoGO+ is a Compton scattering polarimeter ...(20–150keV) optimised for the observation of the Crab (pulsar and wind nebula) and Cygnus X-1 (black hole binary), from a stratospheric balloon-borne platform launched from the Esrange Space Centre in summer 2016. Prior to flight, the response of the polarimeter has been studied with polarised and unpolarised X-rays allowing a Geant4-based simulation model to be validated. The expected modulation factor for Crab observations is found to be MCrab=(41.75±0.85)%, resulting in an expected Minimum Detectable Polarisation (MDP) of 7.3% for a 7day flight. This will allow a measurement of the Crab polarisation parameters with at least 5σ statistical significance assuming a polarisation fraction ∼20% – a significant improvement over the PoGOLite Pathfinder mission which flew in 2013 and from which the PoGO+ design is developed.
In terms of nuclear raw materials, the issue of involving thorium in the fuel cycle is hardly very relevant. However, in view of the large-scale nuclear power development, the use of thorium seems to ...be quite natural and reasonable. The substitution of traditional uranium-plutonium fuel for uranium-thorium fuel in fast neutron reactors will significantly reduce the production of minor actinides, which will make it attractive for the transmutation of long-lived radioactive isotopes of americium, curium and neptunium that have already been and are still being accumulated.
Due to the absence of uranium-233 in nature, the use of thorium in the nuclear power industry requires a closed fuel cycle. At the initial stage of developing the uranium-thorium cycle, it is proposed to use uranium-235 instead of uranium-233 as nuclear fuel.
Studies have been carried out on the transmutation of minor actinides in a fast neutron reactor in which the uranium-thorium cycle is implemented. Several options for the structure of the core of such a reactor have been considered. It has been shown that heterogeneous placement of americium leads to higher rates of its transmutation than homogeneous placement does.
Abstract
A significant problem in the dairy farming industry is the decrease in the livestock reproductive capacity due to the ovaries physiological functions violation. This study examines the ...lipids, proteins and carbohydrates metabolism state, depending on the sexual cyclicity recovery in animals degree, while observing adequate feeding. For the experiment, 16 new-calving Holstein-Friesian cows with an average annual milk yield of 9.5 thousand kg were selected, divided into 2 equal groups, depending on the ovulatory function resumption. All animals received a balanced diet. Blood was taken on days 6, 12, 19, 40 and 68 after calving. Blood serum was separated and the total protein and individual fractions content, as well as the creatinine, urea, total lipids, cholesterol, triglycerides, glucose amount, were determined. To determine the hormonal status, the content of estradiol and progesterone was examined. The reproductive organs condition was assessed using transrectal palpation and using an ultrasound apparatus. We found that cows with ovarian dysfunction are characterized by protein and glucose globulin fraction decreased concentrations in the blood, increased creatinine content and hypothalamus-pituitary-gonad system hormone-producing function inhibition. With an accuracy of 87.5%, the glucose threshold level in the blood serum was revealed, at which ovarian dysfunction can be predicted: a decrease in fertility in cows is observed at a rate of <2.2 mmol/l. Taking into account the previous studies results, further research expediency on finding the hormonal and metabolic status relationship with ethology typological features and the central nervous system state is substantiated.
The dynamics of geomagnetic disturbances and optical airglow at mid-latitude observatories near Irkutsk during a strong magnetospheric storm in the night sector on October 21, 2001, has been studied. ...During the storm, three 1.5-hour intervals of increase in the solar wind (SW) dynamic pressure, which caused intensification of substorm activity, bursts of broadband geomagnetic pulsations, and 557.7 and 630.0 nm auroral emissions, were observed. During these bursts, the southern boundary of the zone of field-aligned currents and the auroral oval approached the observation points, but remained 5°–7° to the north. Possible mechanisms of the amplification of pulsations and optical emissions are related to the effects of SW pressure changes on the magnetosphere: substorm activations, changes in field-aligned and ionospheric currents, and precipitation of both energetic and thermal/superthermal electrons. The features of the high-frequency part of the pulsation spectrum and their spatial distribution are associated with properties of the ionospheric Alfven resonator and the ionospheric MHD waveguide.
We have measured the linear polarization of hard X-ray emission from the Crab in a previously unexplored energy interval, 20–120 keV. The introduction of two new observational parameters, the ...polarization fraction and angle stands to disentangle geometrical and physical effects, thereby providing information on the pulsar wind geometry and magnetic field environment. Measurements are conducted using the PoGOLite Pathfinder – a balloon-borne polarimeter. Polarization is determined by measuring the azimuthal Compton scattering angle of incident X-rays in an array of plastic scintillators housed in an anticoincidence well. The polarimetric response has been characterized prior to flight using both polarized and unpolarized calibration sources. We address possible systematic effects through observations of a background field. The measured polarization fraction for the integrated Crab light curve is
$18.4^{+9.8}_{-10.6}$
per cent, corresponding to an upper limit (99 per cent credibility) of 42.4 per cent, for a polarization angle of (149.2 ± 16.0)°.
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