Asymptotics of Toeplitz Determinants and the Emptiness Formation Probability for the XY Spin Chain

We study an asymptotic behavior of a special correlator known as the Emptiness Formation Probability (EFP) for the one-dimensional anisotropic XY spin-1/2 chain in a transverse magnetic field. This correlator is essentially the probability of formation of a ferromagnetic string of length $n$ in the antiferromagnetic ground state of the chain and plays an important role in the theory of integrable models. For the XY Spin Chain, the correlator can be expressed as the determinant of a Toeplitz matrix and its asymptotical behaviors for $n \to \infty$ throughout the phase diagram are obtained using known theorems and conjectures on Toeplitz determinants. We find that the decay is exponential everywhere in the phase diagram of the XY model except on the critical lines, i.e. where the spectrum is gapless. In these cases, a power-law prefactor with a universal exponent arises in addition to an exponential or Gaussian decay. The latter Gaussian behavior holds on the critical line corresponding to the isotropic XY model, while at the critical value of the magnetic field the EFP decays exponentially. At small anisotropy one has a crossover from the Gaussian to the exponential behavior. We study this crossover using the bosonization approach.Comment: 40 pages, 9 figures, 1 table. The poor quality of some figures is due to arxiv space limitations. If You would like to see the pdf with good quality figures, please contact Fabio Franchini at "[email protected]

Menstrual function and mental health of medical students during the COVID-19 pandemic: a continuous cross-sectional study

Aim. To assess the impact of new coronavirus infection (NCI) and COVID-19 vaccination on menstrual function in comparison with the frequency of depressive disorders during the COVID-19 pandemic among female students of a medical university. Materials and methods. Data for a continuous transverse (cross-sectional) study were obtained using an online survey. The questions included demographics, characteristics of menstrual function, the history of COVID-19 and vaccinations against it, and the standard CES-D (Center for Epidemiologic Studies Depression Scale) questionnaire. The survey included 1.879 female medical students. The exclusion criteria were age under 18 and over 25 years, hormonal contraceptives, pregnancy, childbirth during the last year, and vaccination after COVID-19. After applying the exclusion criteria, three study groups were formed. Group 1 included female students with a history of NCI (n=140), group 2 included students with no history of NCI, who were initially vaccinated against COVID-19 (n=647), group 3 (control group) included unvaccinated students with no history of NCI (n=55). Results. There were no differences in the prevalence of changes in menstrual function in female students after the NCI (49.3%) and after COVID-19 vaccination (39.6%) compared to the control group (43.6%); p=0.477. The rate of depression in the overall study cohort was 43.3%, without any significant differences between the study groups. Significant predictors of changes in menstrual function during the pandemic were marriage (odds ratio OR 2.33 [1.513.61]), depression (OR 1.72 [1.282.3]), a history of menstrual dysfunction (OR 1.5 [0.121.99]), and later menarche (OR 1.76 [1.023.04]). Multivariate analysis did not show the significance of the history of NCI and vaccination as factors of menstrual dysfunction (OR 1.61 [0.892.90] and OR 0.91 [0.591.41], respectively). Conclusion. During the COVID-19 pandemic, female medical students reported frequent changes in menstrual function and depressive disorders. During the pandemic, the most significant predictors of menstrual disorders in female students were depression, a history of menstrual dysfunction, and marriage. A multicenter prospective study is necessary to clarify the mechanisms of the pandemic's impact on menstrual function

Method of Hydrogenous Fuel Usage to Increase the Efficiency in Tandem Diverse Temperature Oxidation System

This paper presents the results of estimation energy efficiency, the collation data of thermodynamic calculations and data on material balance for an assessment of electric and thermal components in considered ways to use convention products, performance enhancement in the tandem system containing the high-temperature fuel cell and the low-temperature fuel cell with full heat regeneration for hydrogenous fuel (CH4). The overall effective efficiency (ηΣef. making full use of the recovered heat) considered tandem system depends on the efficiency of its constituent fuel cells. The overall effective efficiency of the tandem installation including the fuel converter, separating system, high-temperature oxidation system, and hydrogen disposal system in case of fuel use in the low-temperature fuel cell, is higher than for each of the fuel cell elements separately

Method of Hydrogenous Fuel Usage to Increase the Efficiency in Tandem Diverse Temperature Oxidation System

This paper presents the results of estimation energy efficiency, the collation data of thermodynamic calculations and data on material balance for an assessment of electric and thermal components in considered ways to use convention products, performance enhancement in the tandem system containing the high-temperature fuel cell and the low-temperature fuel cell with full heat regeneration for hydrogenous fuel (CH4). The overall effective efficiency (ηΣef. making full use of the recovered heat) considered tandem system depends on the efficiency of its constituent fuel cells. The overall effective efficiency of the tandem installation including the fuel converter, separating system, high-temperature oxidation system, and hydrogen disposal system in case of fuel use in the low-temperature fuel cell, is higher than for each of the fuel cell elements separately

Technological Decision to Renewable Energy Usage Biogas for Off-grid Systems Consumption

This paper presents the results of the energy experiments based on electrochemical researches and the thermodynamic calculations, which are carried out on the hydrogenous fuel with the residual content of methane obtained from biogas selected organic waste. Energy indicators are examined in comparison to electrolysis hydrogen. The use of technical and electro physical indicators together with parameters of the fuel operating allowed assessing energy efficiency the module reformer - fuel cell running on a non-standard hydrogenous fuel. Numerical characteristic the efficiency of workflows fuel system reformer – fuel cell is about 39%. To operate the power installation with a predetermined capacity amount used of hydrogenous fuel is comparable to required electrolysis hydrogen amount. Shown the possibility of creation the systems of power supply based on new hydrogen technologies using renewable energy resources local waste. Confirms the relatively high efficiency the usage of hydrogenous fuel for the tasks of off-grid systems consumption

Technological Decision to Renewable Energy Usage Biogas for Off-grid Systems Consumption

This paper presents the results of the energy experiments based on electrochemical researches and the thermodynamic calculations, which are carried out on the hydrogenous fuel with the residual content of methane obtained from biogas selected organic waste. Energy indicators are examined in comparison to electrolysis hydrogen. The use of technical and electro physical indicators together with parameters of the fuel operating allowed assessing energy efficiency the module reformer - fuel cell running on a non-standard hydrogenous fuel. Numerical characteristic the efficiency of workflows fuel system reformer – fuel cell is about 39%. To operate the power installation with a predetermined capacity amount used of hydrogenous fuel is comparable to required electrolysis hydrogen amount. Shown the possibility of creation the systems of power supply based on new hydrogen technologies using renewable energy resources local waste. Confirms the relatively high efficiency the usage of hydrogenous fuel for the tasks of off-grid systems consumption

Spatial differentiation of regulatory monetary valuation of agricultural land in conditions of widespread irrigation of steppe soils

The article presents results of quality class determination and regulatory and monetary valuation of agricultural land in the steppe soils irrigation zone using the Karmanov’s methodology of soil and climatic quality class determination and author's methodology of ecological, agro-ameliorative and climatic soils quality class determination. Based on the results of spatial modeling, a series of maps was created and characteristics of ecological, agro-ameliorative and relief and climatic components of soils quality class were presented based on the example of the Kherson Region, Ukraine. According to the results soil and climatic quality class determination, it is established that the value of the class varies from 25 to 46 points; the regulatory and monetary value of agricultural land varies from USD 490 per 1 ha for dark chestnut and chestnut alkaline soils up to USD1,360 per ha for ordinary chernozem. According to the results of ecological, agro-ameliorative and climatic soils quality class determination, it is established that the value of the class varies from 6 to 59 points; the regulatory and monetary value of agricultural land varies from USD145 per 1 ha for degraded and highly saline chestnut soils up to USD2,060 per ha for irrigated southern chernozem. The suggested methodology of soil quality class calculation can have multiple purposes. It is intended to be used for different physiographic conditions of land use to develop adaptive soils protection measures at different territorial levels of agricultural production management with the overall objective of ensuring sustainable land use

Spatial Modeling of the Effects of Deflation Destruction of the Steppe Soils of Ukraine

The decrease in the agricultural efficiency is associated with the influence of wind erosion, the consequence of which is a decrease in the soil fertility. Significant effects of wind erosion are typical of the arid and semi arid zones with a small amount of precipitation, high air temperature and degree of evaporation, reinforced by strong winds and low differentiation of plant protection. It has been proven that the intensity of the effects of deflation processes depends on the physical and geographical conditions of the distribution of agricultural land, systematic soil protection activities and the availability of vegetation. It has been established that the acceleration of the deflation processes occurs in the territories with increased anthropogenic pressure, which leads to ecological disturbance of the natural balance characterizing territorial ecosystems. In the course of the studies it was found that the natural processes of wind erosion are significantly enhanced by the absence of a scientifically-based and ecological land development system of agriculture, which leads to destruction of the soil cover, reduction of soil fertility, damage to the agricultural crops and, thus, the economic damage. As a result of application of the GIS and ERS technologies, the empirical-statistical model of the possible soil loss due to wind erosion in the territory of the Steppe zone of Ukraine, it has been found that in the course of the deflation processes in the territory taken by naked fallow upon the absence of the conditions for the deflation resistance activities, the value of soil loss at the epicenter of dust storms can reach about 600 t / ha. Studies proved the importance of the deflation resistant action of the vegetation cover, which tends to an increase in the erosion dangerous (favorable) areas of agricultural land by 1.7 times, which reduces the soil loss by 5.62 times. In accordance with the intensity of the effects of the deflation processes and the increase of the soil losses, the contour and land development deflation resistance activities with elements of soil protection agriculture were proposed

Volatile Organic Compound Fragmentation in the Afterglow of Pulsed Glow Discharge in Ambient Air

Glow discharge (GD) source gained an increased level of attention in relation to the analysis of volatile organic compounds (VOCs) since past work showed that this soft ionization method allowed direct analysis of VOCs with minimal fragmentation, however, the issue of fragmentation was not previously studied in detail. The aim of the present work was to investigate the effect of discharge conditions on VOC fragmentation in the system consisting of the cell with pulsed glow discharge and a time-of-flight mass spectrometer. Ionization of VOCs of different classes (hydrocarbons, alcohols, esters, and carboxylic acids) was investigated. A copper cathode with flat geometry was used. VOCs were ionized in the afterglow of short pulse glow discharge in the air. The use of discharge afterglow significantly reduces or eliminates the effects of ionization mechanisms other than Penning process, in particular, electron ionization. This significantly reduced VOC fragmentation and provided rather low limits of detection. Specific cluster formation was observed for alcohols and esters, which may facilitate their identification