Band Offsets at the Si/SiO2_2 Interface from Many-Body Perturbation Theory

We use many-body perturbation theory, the state-of-the-art method for band gap calculations, to compute the band offsets at the Si/SiO$_2$ interface. We examine the adequacy of the usual approximations in this context. We show that (i) the separate treatment of band-structure and potential lineup contributions, the latter being evaluated within density-functional theory, is justified, (ii) most plasmon-pole models lead to inaccuracies in the absolute quasiparticle corrections, (iii) vertex corrections can be neglected, (iv) eigenenergy self-consistency is adequate. Our theoretical offsets agree with the experimental ones within 0.3 eV

First-principles study on dielectric properties of NaCl crystal and ultrathin NaCl films under finite external electric field

We present a first-principles study on the dielectric properties of an NaCl crystal and ultrathin NaCl films under a finite external electric field. Our results show that the high-frequency dielectric constant of the films is not affected by the finite size effect from crystal surfaces and is close to that of the crystal, whereas the static one is sensitive to the thickness of the film due to the difference in the atomic configurations between the surface and inside of the film.Comment: 11 pages and 4 figure

Dielectric screening in extended systems using the self-consistent Sternheimer equation and localized basis sets

We develop a first-principles computational method for investigating the dielectric screening in extended systems using the self-consistent Sternheimer equation and localized non-orthogonal basis sets. Our approach does not require the explicit calculation of unoccupied electronic states, only uses two-center integrals, and has a theoretical scaling of order O(N^3). We demonstrate this method by comparing our calculations for silicon, germanium, diamond, and LiCl with reference planewaves calculations. We show that accuracy comparable to planewaves calculations can be achieved via a systematic optimization of the basis set.Comment: 6 pages, 3 figure

GW method with the self-consistent Sternheimer equation

We propose a novel approach to quasiparticle GW calculations which does not require the computation of unoccupied electronic states. In our approach the screened Coulomb interaction is evaluated by solving self-consistent linear-response Sternheimer equations, and the noninteracting Green's function is evaluated by solving inhomogeneous linear systems. The frequency-dependence of the screened Coulomb interaction is explicitly taken into account. In order to avoid the singularities of the screened Coulomb interaction the calculations are performed along the imaginary axis, and the results are analytically continued to the real axis through Pade' approximants. As a proof of concept we implemented the proposed methodology within the empirical pseudopotential formalism and we validated our implementation using silicon as a test case. We examine the advantages and limitations of our method and describe promising future directions.Comment: 18 pages, 6 figure

Physical activity levels and related energy expenditure during COVID-19 quarantine among the sicilian active population: A cross-sectional online survey study

Background: During the coronavirus disease 2019 (COVID-19) pandemic, the Italian government has adopted containment measures to control the virus's spread, including limitations to the practice of physical activity (PA). The aim of this study was to estimate the levels of PA, expressed as energy expenditure (MET-minute/week), among the physically active Sicilian population before and during the last seven days of the COVID-19 quarantine. Furthermore, the relation between this parameter and specific demographic and anthropometric variables was analyzed. Methods: 802 Sicilian physically active participants (mean age: 32.27 ± 12.81 years; BMI: 23.44 ± 3.33 kg/m2) were included in the study and grouped based on gender, age and BMI. An adapted version of the International Physical Activity Questionnaire-short form (IPAQ-SF) was administered to the participants through an online survey. The Wilcoxon signed-rank test and the Kruskal-Wallis rank-sum test were used for statistical analyses. Results: As expected, we observed a significant decrease of the total weekly energy expenditure during the COVID-19 quarantine (p < 0.001). A significant variation in the MET-min/wk in the before quarantine condition (p = 0.046) and in the difference between before and during quarantine (p = 0.009) was found for males and females. The male group decreased the PA level more than the female one. Moreover, a significant difference in the MET-min/wk was found among groups distributions of BMI (p < 0.001, during quarantine) and of age (p < 0.001, both before and during quarantine). In particular, the highest and the lowest levels of PA were reported by the young and the elderly, respectively, both before and during quarantine. Finally, the overweight group showed the lowest level of PA during quarantine. Conclusion: Based on our outcomes, we can determine that the current quarantine has negatively affected the practice of PA, with greater impacts among males and overweight subjects. In regards to different age groups, the young, young adults and adults were more affected than senior adults and the elderly

Saddle Pressures Factors in Road and Off-Road Cyclists of Both Genders: A Narrative Review

: The contact point of the pelvis with the saddle of the bicycle could generate abnormal pressure, which could lead to injuries to the perineum in cyclists. The aim of this review was to summarize in a narrative way the current literature on the saddle pressures and to present the factors that influence saddle pressures in order to prevent injury risk in road and off-road cyclists of both genders. We searched the PubMed database to identify English-language sources, using the following terms: "saddle pressures", "pressure mapping", "saddle design" AND "cycling". We also searched the bibliographies of the retrieved articles. Saddle pressures are influenced by factors such as sitting time on the bike, pedaling intensity, pedaling frequency, trunk and hand position, handlebars position, saddle design, saddle height, padded shorts, and gender. The jolts of the perineum on the saddle, especially on mountain bikes, generate intermittent pressures, which represent a risk factor for various pathologies of the urogenital system. This review highlights the importance of considering these factors that influence saddle pressures in order to prevent urogenital system injuries in cyclists

Apogeotropic posterior semicircular canal benign paroxysmal positional vertigo: some clinical and therapeutic considerations

We lately reported the cases of patients complaining positional vertigo whose nystagmic pattern was that of a peripheral torsional vertical positional down beating nystagmus originating from a lithiasis of the non-ampullary arm of the posterior semicircular canal (PSC). We considered this particular pathological picture the apogeotropic variant of PSC benign paroxysmal positional vertigo (BPPV). Since the description of the pilot cases we observed more than 150 patients showing the same clinical sign and course of symptoms. In this paper we describe, in detail, both nystagmus of apogeotropic PSC BPPV (A-PSC BPPV) and symptoms reported by patients trying to give a reasonable explanation for these clinical features. Moreover we developed two specific physical therapies directed to cure A-PSC BPPV. Preliminary results of these techniques are related

Factors affecting the development of Bovine Respiratory Disease: a cross-sectional study in beef steers shipped from France to Italy

Bovine respiratory disease (BRD) is a complex, multifactorial syndrome and one of the major welfare and economical concerns for the cattle industry. This 1-year cross-sectional study was aimed at documenting the prevalence of BRD-related pathogens and clinical signs before and after a long journey and at identifying possible predisposition factors. Male Limousine beef steers (n = 169) traveling from France to Italy were health checked and sampled with Deep Nasopharyngeal Swabs (DNS) at loading (T0) and 4 days after arrival (T1). Real-time quantitative PCR was used to quantify the presence of bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), bovine alphaherpesvirus 1 (BoHV-1), bovine coronavirus (BCoV), bovine adenovirus (BAdV), bovine parainfluenza virus 3 (BPIV-3), Histophilus somni, Mannheimia haemolytica, Mycoplasma bovis, and Pasteurella multocida. Weather conditions at departure and arrival were recorded, and the travel conditions were taken from the travel documentation. At T0, even if no animals displayed clinical signs, some of them were already positive for one or more pathogens. At T1, the number of animals displaying clinical signs and positive for BCoV, BAdV, BRSV, H. somni, M. haemolytica, M. bovis, and P. multocida increased dramatically (p < 0.001). Transport also significantly increased co-infection passing from 16.0% at T0 to 82.8% at T1 (p < 0.001). An extra stop during the journey seemed to favor BRSV, M. haemolytica, and P. multocida (p < 0.05). Weather conditions, in particular sudden climate changes from departure to arrival and daily temperature variance, were found to be predisposing factors for many of the pathogens. The farm of arrival also played a role for BRSV, BAdV, and H. somni (p < 0.05). BCoV increased dramatically, but no associations were found confirming that it spreads easily during transport phases. Our findings increased our understanding of factors increasing the likelihood of BRD-related pathogens shedding and can be useful to minimize the incidence of BRD and to implement animal transport regulations

Physical fitness assessment in Goalball: A scoping review of the literature

Background: Goalball is a Paralympic sport for visually impaired athletes. Although it is widely practiced, a great variety of tests are adopted to evaluate athletes' physical fitness. Therefore, the objective was to identify the physical fitness tests adopted in this sport to find the common aspects between them and, eventually, to propose a standard operating procedure. Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines were adopted. The studies were extracted from PubMed, Web of Science, and Scopus. A selection process by title, abstract, and full-text, according to the inclusion and exclusion criteria, was performed. The results were discussed with narrative synthesis. Results: A total of 7 papers and 222 participants were included. A wide variety of tests were adopted and the Brockport Physical Fitness Test (BPFT) was the only battery included to evaluate general athletes' well-being. Conclusions: Although few literature exists on Goalball, the BPFT could be the battery for evaluating Goalball athletes though the test battery should be standardized to the characteristics of this sport