Electronic structure of turbostratic graphene

We explore the rotational degree of freedom between graphene layers via the simple prototype of the graphene twist bilayer, i.e., two layers rotated by some angle $\theta$. It is shown that, due to the weak interaction between graphene layers, many features of this system can be understood by interference conditions between the quantum states of the two layers, mathematically expressed as Diophantine problems. Based on this general analysis we demonstrate that while the Dirac cones from each layer are always effectively degenerate, the Fermi velocity $v_F$ of the Dirac cones decreases as $\theta\to 0^\circ$; the form we derive for $v_F(\theta)$ agrees with that found via a continuum approximation in Phys. Rev. Lett., 99:256802, 2007. From tight binding calculations for structures with $1.47^\circ \le \theta < 30^\circ$ we find agreement with this formula for $\theta \gtrsim 5^\circ$. In contrast, for $\theta \lesssim 5^\circ$ this formula breaks down and the Dirac bands become strongly warped as the limit $\theta \to 0$ is approached. For an ideal system of twisted layers the limit as $\theta\to0^\circ$ is singular as for $\theta > 0$ the Dirac point is fourfold degenerate, while at $\theta=0$ one has the twofold degeneracy of the $AB$ stacked bilayer. Interestingly, in this limit the electronic properties are in an essential way determined \emph{globally}, in contrast to the 'nearsightedness' [W. Kohn. Phys. Rev. Lett., 76:3168, 1996.] of electronic structure generally found in condensed matter.Comment: Article as to be published in Phys. Rev B. Main changes: K-point mapping tables fixed, several changes to presentation

Nonlinear Resonance of Superconductor/Normal Metal Structures to Microwaves

We study the variation of the differential conductance $G=dj/dV$ of a normal metal wire in a Superconductor/Normal metal heterostructure with a cross geometry under external microwave radiation applied to the superconducting parts. Our theoretical treatment is based on the quasiclassical Green's functions technique in the diffusive limit. Two limiting cases are considered: first, the limit of a weak proximity effect and low microwave frequency, second, the limit of a short dimension (short normal wire) and small irradiation amplitude.Comment: 11 pages, 10 figure

Evaluation of School Readiness Outcomes in Preterm and SGA Infant

The early preterm and SGA children show lower scores then term infants: high and medium scores were seen 84,8% in I Group; 47,1% in II group; and 48,1% in III group and 79,6% in Control group accordingly. Elementary school readiness scores was i

Magnitude and determinants of excess total, age-specific and sex-specific all-cause mortality in 24 countries worldwide during 2020 and 2021: results on the impact of the COVID-19 pandemic from the C-MOR project.

INTRODUCTION: To examine the impact of the COVID-19 pandemic on mortality, we estimated excess all-cause mortality in 24 countries for 2020 and 2021, overall and stratified by sex and age. METHODS: Total, age-specific and sex-specific weekly all-cause mortality was collected for 2015-2021 and excess mortality for 2020 and 2021 was calculated by comparing weekly 2020 and 2021 age-standardised mortality rates against expected mortality, estimated based on historical data (2015-2019), accounting for seasonality, and long-term and short-term trends. Age-specific weekly excess mortality was similarly calculated using crude mortality rates. The association of country and pandemic-related variables with excess mortality was investigated using simple and multilevel regression models. RESULTS: Excess cumulative mortality for both 2020 and 2021 was found in Austria, Brazil, Belgium, Cyprus, England and Wales, Estonia, France, Georgia, Greece, Israel, Italy, Kazakhstan, Mauritius, Northern Ireland, Norway, Peru, Poland, Slovenia, Spain, Sweden, Ukraine, and the USA. Australia and Denmark experienced excess mortality only in 2021. Mauritius demonstrated a statistically significant decrease in all-cause mortality during both years. Weekly incidence of COVID-19 was significantly positively associated with excess mortality for both years, but the positive association was attenuated in 2021 as percentage of the population fully vaccinated increased. Stringency index of control measures was positively and negatively associated with excess mortality in 2020 and 2021, respectively. CONCLUSION: This study provides evidence of substantial excess mortality in most countries investigated during the first 2 years of the pandemic and suggests that COVID-19 incidence, stringency of control measures and vaccination rates interacted in determining the magnitude of excess mortality

Excess all-cause mortality and COVID-19-related mortality: a temporal analysis in 22 countries, from January until August 2020

Background This study aimed to investigate overall and sex-specific excess all-cause mortality since the inception of the COVID-19 pandemic until August 2020 among 22 countries. Methods Countries reported weekly or monthly all-cause mortality from January 2015 until the end of June or August 2020. Weekly or monthly COVID-19 deaths were reported for 2020. Excess mortality for 2020 was calculated by comparing weekly or monthly 2020 mortality (observed deaths) against a baseline mortality obtained from 2015–2019 data for the same week or month using two methods: (i) difference in observed mortality rates between 2020 and the 2015–2019 average and (ii) difference between observed and expected 2020 deaths. Results Brazil, France, Italy, Spain, Sweden, the UK (England, Wales, Northern Ireland and Scotland) and the USA demonstrated excess all-cause mortality, whereas Australia, Denmark and Georgia experienced a decrease in all-cause mortality. Israel, Ukraine and Ireland demonstrated sex-specific changes in all-cause mortality. Conclusions All-cause mortality up to August 2020 was higher than in previous years in some, but not all, participating countries. Geographical location and seasonality of each country, as well as the prompt application of high-stringency control measures, may explain the observed variability in mortality changes

Observações citológicas em citrus: ll. variedades triplóides

No presente trabalho apresenta-se um breve resumo dos conhecimentos atuais sôbre a citologia do gênero Citrus; descrevem-se, a seguir, duas variedades triplóides de interêsse econômico. Admite-se que uma delas se tenha derivado da outra por meio de um "seedling" nucelar. Os caracteres morfológicos e citológicos dêstes triplóides são apresentados em detalhes. Chama-se a atenção para a importância da triploidia nos trabalhos de melhoramento das plantas cítricas.<br>A review is presented of citrus cytology and account is given of the author's investigations of this subject. Two triploid citrus varieties are described which are of economic importance. It appears probable that one of these is a nucellar seedling derived from the other. The morphological and cytological characteristics of these triploids are given in detail. Attention is called to the importance of triploidy in citrus breeding

Cause-Specific Excess Mortality During the COVID-19 Pandemic (2020–2021) in 12 Countries of the C-MOR Consortium

Background This study investigated cause-specific mortality rates in 12 countries during the COVID-19 pandemic in 2020 and 2021. Methods We collected weekly cause-specific mortality data from respiratory disease, pneumonia, cardiovascular disease (CVD) and cancer from national vital statistic databases. We calculated excess mortality for respiratory disease (excluding COVID-19 codes), pneumonia, and CVD in 2020 and 2021 by comparing observed weekly against expected mortality based on historical data (2015–2019), accounting for seasonal trends. We used multilevel regression models to investigate the association between country-level pandemic-related variables and cause-specific mortality. Results Significant reductions in cumulative mortality from respiratory disease and pneumonia were observed in 2020 and/or 2021, except for Georgia, Northern Ireland, Kazakhstan, and Ukraine, which exhibited excess mortality for one or both causes. Australia, Austria, Cyprus, Georgia, and Northern Ireland experienced excess cumulative CVD mortality in 2020 and/or 2021. Australia, Austria, Brazil, Cyprus, Georgia, Northern Ireland, Scotland and Slovenia, experienced increased crude cumulative cancer mortality during 2020 and/or 2021 compared to previous years. Among pandemic-related variables, reported COVID-19 incidence was negatively associated with increased cancer mortality, excess respiratory, (2020) and pneumonia (2021) mortality, and positively associated with respiratory and CVD mortality (2021). Stringency of control measures were negatively associated with excess respiratory disease, CVD, and increased cancer mortality (2021). Conclusions This study provides evidence of substantial excess mortality from CVD, and notable reductions in respiratory disease and pneumonia in both years across most countries investigated. Our study also highlights the beneficial impact of stringent control measures in mitigating excess mortality from most causes in 2021

Cause-Specific Excess Mortality During the COVID-19 Pandemic (2020-2021) in 12 Countries of the C-MOR Consortium.

BACKGROUND: This study investigated cause-specific mortality rates in 12 countries during the COVID-19 pandemic in 2020 and 2021. METHODS: We collected weekly cause-specific mortality data from respiratory disease, pneumonia, cardiovascular disease (CVD) and cancer from national vital statistic databases. We calculated excess mortality for respiratory disease (excluding COVID-19 codes), pneumonia, and CVD in 2020 and 2021 by comparing observed weekly against expected mortality based on historical data (2015-2019), accounting for seasonal trends. We used multilevel regression models to investigate the association between country-level pandemic-related variables and cause-specific mortality. RESULTS: Significant reductions in cumulative mortality from respiratory disease and pneumonia were observed in 2020 and/or 2021, except for Georgia, Northern Ireland, Kazakhstan, and Ukraine, which exhibited excess mortality for one or both causes. Australia, Austria, Cyprus, Georgia, and Northern Ireland experienced excess cumulative CVD mortality in 2020 and/or 2021. Australia, Austria, Brazil, Cyprus, Georgia, Northern Ireland, Scotland and Slovenia, experienced increased crude cumulative cancer mortality during 2020 and/or 2021 compared to previous years. Among pandemic-related variables, reported COVID-19 incidence was negatively associated with increased cancer mortality, excess respiratory, (2020) and pneumonia (2021) mortality, and positively associated with respiratory and CVD mortality (2021). Stringency of control measures were negatively associated with excess respiratory disease, CVD, and increased cancer mortality (2021). CONCLUSIONS: This study provides evidence of substantial excess mortality from CVD, and notable reductions in respiratory disease and pneumonia in both years across most countries investigated. Our study also highlights the beneficial impact of stringent control measures in mitigating excess mortality from most causes in 2021