96 research outputs found
High volumetric capacitance near insulator-metal percolation transition
A new type of a capacitor with a very high volumetric capacitance is
proposed. It is based upon the known phenomenon of a sharp increase of the
dielectric constant of the metal-insulator composite in the vicinity of the
percolation threshold, but still on the insulator side. The optimization
suggests that the metallic particles should be of nanoscale and that the
distance between planar electrodes should be somewhat larger than the
correlation length of the percolation theory and 10 to 20 times larger than the
size of the particles while the area of the electrodes might be unlimited. The
random electric field in the capacitors is found to be larger than the average
field corresponding to the potential difference of electrodes. This random
field is potentially responsible for dielectric breakdown. The estimated
breakdown voltage of the new capacitor shows that the stored energy density
might be significantly larger than that of electrolytic capacitors while the
volumetric capacitances might be comparable. The charging and discharging times
should be significantly smaller than corresponding times of batteries and even
electrolytic capacitors.Comment: 10 pages 1 EPS figur
Use of branched-chain amino acids for reducing exercise-caused skeletal muscle damage
Introduction: Skeletal muscles damage (direct and vicarious) slows down the recovery processes in patients with injuries of the musculoskeletal system. It occurs in the early postoperative period as well. An increase in the rigidity of the skeletal muscle extracellular matrix can reduce pain, tissue swelling, and accelerate the recovery of contractility.Objective: The analyses of the effect of branched-chain amino acids (BCAAs) intake on the expression of IGF1 genes, type 1, 3 and 5 collagen, which are crucial in the composition of the skeletal muscle extracellular matrix, as well as on the muscle membrane damage against the background of chronic damage to skeletal muscles.Material and methods: 12 young healthy male subjects, skiers aged 19 (18; 22) received a placebo treatment (maltodextrin, 100 mg/kg body weight/day; n = 6) or a mixture of amino acids (leucine, isoleucine, valine – 50:25:20 mg/kg body weight/day respectively; n = 6). The treatment was received daily against the background of a large amount of aerobic high-intensity training (up to 22 hours per week). Before and after the amino acids intake a biopsy of the musculus vastus lateralis was performed, and venous blood samples were taken during the experiment.Results: The intake of leucine against the background of training led not only to a pronounced increase in the level of IGF1 protein in blood by 1.5 times (which corresponds to the literature data), but also to a trend towards an increase in the expression of IGF1Ea mRNA by 1.8 times in the skeletal muscle, and a decrease in the level of markers of muscle membranes damage – creatine phosphokinase (CPK) activity and myoglobin. In addition, changes in the IGF1-dependent collagen genes expression strongly correlated with changes in IGF1Ea expression, but not with IGF1 protein in blood (pooled group, n = 12). Thus, the intake of leucine as a part of the essential amino acids can reduce damage to skeletal muscles caused by excessive physical activity, lack of physical activity, or direct trauma.Conclusion: A 10-week BCAAs intake by individuals with documented chronic muscle membrane damage caused an increase of basal levels of IGF1 in blood and a trend towards increased IGF1Ea mRNA expression in skeletal muscle, and also caused a modest reduction in damage of skeletal muscle membrane
Casimir force calculations near the insulator-conductor transition in gold thin films
We present theoretical calculations of the Casimir force for Au thin films
near the insulator-conductor transition that has been observed experimentally.
The dielectric function of the Au thin films is described by the Drude-Smith
model. The parameters needed to model the dielectric function such as the
relaxation time, plasma frequency and the backscattering constant depend on the
thickness of the film. The Casimir force decreases as the film thickness
decreases until it reaches a minimum after which the force increases again. The
minimum of the force coincides with the critical film thickness where a
percolation conductor-insulator occurs.Comment: 5 figures, 1 tabl
Divergence of the dielectric constant in ultrathin granular metal films near the percolation threshold
We report on the electronic and optical properties of ultrathin granular films. We demonstrate that the static dielectric constant increases with thickness in the dielectric regime and diverges at the critical thickness, as predicted by classical percolation theory. However, for thicker samples, the dc conductivity does not obey scaling laws due to the presence of tunneling conduction. In this region the dielectric constant is positive, and the electronic transport is not metallic but can be described by Jonscher's universal power law, even though there is a Drude-like response indicating the presence of free charge carriers. Only for thicker films when the dielectric constant becomes negative is there metallic conduction
THE INTERRELATION OF CHANGES IN LABORATORY PARAMETERS OF HOMEOSTASIS AND MORTALITY IN ELDER AGE GROUPS PATIENTS WITH POLYTRAuMA AND THE DOMINANT INJURIES OF THE MUSCULOSKELETAL SYSTEM
In this work the analysis of observations of patients with polytrauma of older age groups (95 patients) was performed, the control group consisted of patients with polytrauma in age from 20 to 40 years (55 patients). The aim of the study was to define a set of laboratory parameters and the degree of deviation from the norm, the changes of which most closely correlated with the dynamics of the patients' condition, allowing objectively justify the choice of treatment strategy on the stages of DCS. Among them are the blood count (RBC, HGB), total blood protein, blood albumin and abnormalities in blood coagulation system. Objectivization of assessing criteria of condition permitted to reduce the mortality rate by 9.6%
Properties of Calcium Phosphate/Hydrogel Bone Grafting Composite on the Model of Diaphyseal Rat Femur’s Defect: Experimental Study
Background. The problem of bone defects replacement is relevant nowadays, that is why many scientists create new synthetic bone substitutes, but the ideal material has not been found so far.
The aims of the study: 1) to determine the suitability of the monocortical defect model in the rat femur diaphysis with additional prophylactic reinforcement with a bone plate for assessing the biological properties of implanted materials using the commercially available ChronOS material as an example; 2) to assess of the osteoconductive properties of composite materials based on poly(ethylene glycol)diacrylate and octacalcium phosphate with architecture Kelvin and gyroid types on the developed model.
Methods. A prospective study, level of evidence II. A monocortical defect of the rat femoral diaphysis (length 7 mm) was produced under anaesthesia in aseptic conditions and fixed with a polyetheretherketone plate and six titanium screws. In the control group, the defect was left empty. In other groups, blocks of one of three materials were implanted сhronOS and composites of poly(ethylene glycol)diacrylate and octacalcium phosphate with 3D-printed Kelvin and gyroid architectures. After 3 and 6 weeks, the rats were sacrificed, and histological examination of the defect zone was performed. The amount of newly formed bone tissue was histometricly assessed, followed by statistical processing of the results.
Results. All rats have reached the planned endpoint, and there were no infectious complications or loss of fixation. Histological examination of the defect zone revealed minimal bone growth in the Control group, rather slow bone formation in the Gyroid group, and statistically significantly more pronounced bone formation in the pores of the materials in the Kelvin and Chronos groups.
Conclusions. Bone defect in this model was not spontaneously filled with bone tissue and allowed us to study the biological properties of bone substitutes (the ability to biodegrade and osteoconductive properties). The osteoconductive properties of a composite material based on poly(ethylene glycol)diacrylate and octacalcium phosphate with a Kelvin architecture are higher than with a gyroid architecture and are comparable to that of the сhronOS
COVIDiSTRESS Global Survey dataset on psychological and behavioural consequences of the COVID-19 outbreak
This N = 173,426 social science dataset was collected through the collaborative COVIDiSTRESS Global Survey – an open science effort to improve understanding of the human experiences of the 2020 COVID-19 pandemic between 30th March and 30th May, 2020. The dataset allows a cross-cultural study of psychological and behavioural responses to the Coronavirus pandemic and associated government measures like cancellation of public functions and stay at home orders implemented in many countries. The dataset contains demographic background variables as well as measures of Asian Disease Problem, perceived stress (PSS-10), availability of social provisions (SPS-10), trust in various authorities, trust in governmental measures to contain the virus (OECD trust), personality traits (BFF-15), information behaviours, agreement with the level of government intervention, and compliance with preventive measures, along with a rich pool of exploratory variables and written experiences. A global consortium from 39 countries and regions worked together to build and translate a survey with variables of shared interests, and recruited participants in 47 languages and dialects. Raw plus cleaned data and dynamic visualizations are available
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A creative destruction approach to replication: implicit work and sex morality across cultures
How can we maximize what is learned from a replication study? In the creative destruction approach to replication, the original hypothesis is compared not only to the null hypothesis, but also to predictions derived from multiple alternative theoretical accounts of the phenomenon. To this end, new populations and measures are included in the design in addition to the original ones, to help determine which theory best accounts for the results across multiple key outcomes and contexts. The present pre-registered empirical project compared the Implicit Puritanism account of intuitive work and sex morality to theories positing regional, religious, and social class differences; explicit rather than implicit cultural differences in values; self-expression vs. survival values as a key cultural fault line; the general moralization of work; and false positive effects. Contradicting Implicit Puritanism's core theoretical claim of a distinct American work morality, a number of targeted findings replicated across multiple comparison cultures, whereas several failed to replicate in all samples and were identified as likely false positives. No support emerged for theories predicting regional variability and specific individual-differences moderators (religious affiliation, religiosity, and education level). Overall, the results provide evidence that work is intuitively moralized across cultures
Predictors of enhancing human physical attractiveness: Data from 93 countries
People across the world and throughout history have gone to great lengths to enhance their physical appearance. Evolutionary psychologists and ethologists have largely attempted to explain this phenomenon via mating preferences and strategies. Here, we test one of the most popular evolutionary hypotheses for beauty-enhancing behaviors, drawn from mating market and parasite stress perspectives, in a large cross-cultural sample. We also test hypotheses drawn from other influential and non-mutually exclusive theoretical frameworks, from biosocial role theory to a cultural media perspective. Survey data from 93,158 human participants across 93 countries provide evidence that behaviors such as applying makeup or using other cosmetics, hair grooming, clothing style, caring for body hygiene, and exercising or following a specific diet for the specific purpose of improving ones physical attractiveness, are universal. Indeed, 99% of participants reported spending >10 min a day performing beauty-enhancing behaviors. The results largely support evolutionary hypotheses: more time was spent enhancing beauty by women (almost 4 h a day, on average) than by men (3.6 h a day), by the youngest participants (and contrary to predictions, also the oldest), by those with a relatively more severe history of infectious diseases, and by participants currently dating compared to those in established relationships. The strongest predictor of attractiveness-enhancing behaviors was social media usage. Other predictors, in order of effect size, included adhering to traditional gender roles, residing in countries with less gender equality, considering oneself as highly attractive or, conversely, highly unattractive, TV watching time, higher socioeconomic status, right-wing political beliefs, a lower level of education, and personal individualistic attitudes. This study provides novel insight into universal beauty-enhancing behaviors by unifying evolutionary theory with several other complementary perspectives
Examining the generalizability of research findings from archival data
This initiative examined systematically the extent to which a large set of archival research findings generalizes across contexts. We repeated the key analyses for 29 original strategic management effects in the same context (direct reproduction) as well as in 52 novel time periods and geographies; 45% of the reproductions returned results matching the original reports together with 55% of tests in different spans of years and 40% of tests in novel geographies. Some original findings were associated with multiple new tests. Reproducibility was the best predictor of generalizability-for the findings that proved directly reproducible, 84% emerged in other available time periods and 57% emerged in other geographies. Overall, only limited empirical evidence emerged for context sensitivity. In a forecasting survey, independent scientists were able to anticipate which effects would find support in tests in new samples
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