Evidence for contact delocalization in atomic scale friction

We analyze an advanced two-spring model with an ultra-low effective tip mass to predict nontrivial and physically rich 'fine structure' in the atomic stick-slip motion in Friction Force Microscopy (FFM) experiments. We demonstrate that this fine structure is present in recent, puzzling experiments. This shows that the tip apex can be completely or partially delocalized, thus shedding new light on what is measured in FFM and, possibly, what can happen with the asperities that establish the contact between macroscopic sliding bodies.Comment: 4 pages text and 3 figure

A hierarchy of models related to nanoflows and surface diffusion

In last years a great interest was brought to molecular transport problems at nanoscales, such as surface diffusion or molecular flows in nano or sub-nano-channels. In a series of papers V. D. Borman, S. Y. Krylov, A. V. Prosyanov and J. J. M. Beenakker proposed to use kinetic theory in order to analyze the mechanisms that determine mobility of molecules in nanoscale channels. This approach proved to be remarkably useful to give new insight on these issues, such as density dependence of the diffusion coefficient. In this paper we revisit these works to derive the kinetic and diffusion models introduced by V. D. Borman, S. Y. Krylov, A. V. Prosyanov and J. J. M. Beenakker by using classical tools of kinetic theory such as scaling and systematic asymptotic analysis. Some results are extended to less restrictive hypothesis

Materials based on BIFEVOX and bismuth or iron simple oxides nanopowders

Received: 22.09.2017; accepted: 17.10.2017; published: 20.10.2017.Compositions of composite materials based on BIFEVOX and nanopowders of bismuth and iron oxides have been obtained. The absence of chemical interaction between the components has been proved, the total electrical conductivity of materials in the average temperature region has been determined. It has been shown that under the selected formation conditions, it has not yet been possible to achieve significant improvement of the functional characteristics of heterogeneous compositions in comparison with individual phases. However positive results on chemical and structural stability give way to further investigations.The work was partially supported by the Scholarship of the President (SP-3376.2016.1) and Russian Foundation for Basic Research (project No 17-53-04098)

Association of the rs2167270 polymorphism of the leptin gene (LEP) with the intensity of pain in patients with osteoarthritis of the knee

Background: Osteoarthritis (OA) is a significant social problem as it is the most common disease of the joints. OA is a multifactorial disease in which great attention is paid to hereditary factors. Recently, a number of studies have demonstrated the contribution of a number of genes to the subjective assessment of pain in OA, which is the main symptom of this disease. The association of P2X7, TRPV1 and TACR1 genes and some others with pain sensitivity has been shown. One of the risk factors of pain among many others, is the increased weight. Abdominal adipose tissue is a source of release of pro-inflammatory adipokines that cause systemic inflammation associated with damage to many tissues, including subchondral bone, synovial membrane. Leptin is an endogenous hormone from the adipokine family encoded by the obesity gene leptin (LEP) and which is synthesized primarily in adipocytes.Aims: To investigate the possible association of rs2167270 (A19G) polymorphism of the LEP gene with pain intensity in ­patients with knee OA.Materials and methods: The study was conducted among women diagnosed with OA. Using the VAS scale (Visual analog scale), patients with mild knee pain — group 1 (VAS ≤ 40 mm) and patients with moderate or severe pain — group 2 (VAS>40 mm) were selected for pain assessment. Genetic variants of A19G leptin gene polymorphism were studied by polymerase chain reaction followed by restriction fragment length analysis (PCR-RFLP) method.Results: In the group of patients with moderate or severe pain intensity (group 2, n=61), a statistically significant association was shown with a higher body mass index (p=0.006) and an increased frequency of carriers of the 19GG genotype (p=0,051) compared to group 1 (n=36). Carriers of the 19GG genotype statistically significantly had a higher rate of knee pain and an early age of OA debut compared to carriers of the 19AA genotype (p=0,035 and p=0,015, respectively).Conclusions: The findings open up new possibilities for predicting pain symptoms in patients with knee OA by genetic testing of A19G polymorphic variants of the leptin gene

Связь генетического полиморфизма острофазового маркера воспаления rs12218 гена SAA1 с клиническими фенотипами ювенильного идиопатического артрита

Objective: to test the hypothesis of a possible relationship between the rs12218 polymorphism of the SAA1 gene and a predisposition to different clinical phenotypes of juvenile idiopathic arthritis (JIA).Patients and methods. Genetic typing of rs12218 polymorphism was carried out in 142 children: 77 of them were diagnosed with JIA, including 30 patients with oligoarthritis (oJIA), 20 with polyarthritis (pJIA), and 27 with systemic onset (sJIA). Sixty five healthy volunteers were included in the control group. The rs12218 polymorphism of the SAA1 gene was investigated using real-time polymerase chain reaction.Results and discussion. A high risk of developing the clinical phenotype of oJIA in carriers of the C mutant allele of the rs12218 T/C polymorphism of the SAA1 gene was established. Statistically significant differences between the clinical phenotypes of oJIA and sJIA in the frequency distribution of genotypes and alleles of rs12218 T/C polymorphism of the SAA1 gene are shown.Conclusion. The results of the studies have confirmed the important role of the rs12218 T/C polymorphism of the SAA1 gene in the formation of susceptibility to clinical variants of JIA.Цель исследования – проверка гипотезы о возможной связи полиморфизма rs12218 гена SAA1 с предрасположенностью к разным клиническим фенотипам ювенильного идиопатического артрита (ЮИА).Пациенты и методы. Проведено генетическое типирование полиморфизма rs12218 у 142 детей: 77 из них имели диагноз ЮИА, включая 30 пациентов с олигоартритом (оЮИА), 20 с полиартритом (пЮИА) и 27 с системным началом (сЮИА), а 65 здоровых волонтеров вошли в контрольную группу. Полиморфизм rs12218 гена SAA1 исследовали с помощью полимеразной цепной реакции в режиме реального времени.Результаты и обсуждение. Установлен высокий риск развития клинического фенотипа оЮИА у носителей мутантного аллеля С полиморфизма rs12218 T/C гена SAA1. Показаны статистически значимые различия между клиническими фенотипами оЮИА и сЮИА в распределении частот генотипов и аллелей rs12218 T/C полиморфизма гена SAA1.Заключение. Результаты проведенных исследований подтвердили важное участие полиморфизма rs12218 T/C гена SAA1 в формировании предрасположенности к клиническим вариантам ЮИА

Molecular random walks and invariance group of the Bogolyubov equation

Statistics of molecular random walks in a fluid is considered with the help of the Bogolyubov equation for generating functional of distribution functions. An invariance group of solutions to this equation as functions of the fluid density is discovered. It results in many exact relations between probability distribution of the path of a test particle and its irreducible correlations with the fluid. As the consequence, significant restrictions do arise on possible shapes of the path distribution. In particular, the hypothetical Gaussian form of its long-range asymptotic proves to be forbidden (even in the Boltzmann-Grad limit). Instead, a diffusive asymptotic is allowed which possesses power-law long tail (cut off by ballistic flight length).Comment: 23 pages, no figures, LaTeX AMSART, author's translation from Russian of the paper accepted to the TMPh (``Theoretical and mathematical physics''

Generalized probabilities taking values in non-Archimedean fields and topological groups

We develop an analogue of probability theory for probabilities taking values in topological groups. We generalize Kolmogorov's method of axiomatization of probability theory: main distinguishing features of frequency probabilities are taken as axioms in the measure-theoretic approach. We also present a review of non-Kolmogorovian probabilistic models including models with negative, complex, and $p$-adic valued probabilities. The latter model is discussed in details. The introduction of $p$-adic (as well as more general non-Archimedean) probabilities is one of the main motivations for consideration of generalized probabilities taking values in topological groups which are distinct from the field of real numbers. We discuss applications of non-Kolmogorovian models in physics and cognitive sciences. An important part of this paper is devoted to statistical interpretation of probabilities taking values in topological groups (and in particular in non-Archimedean fields)

Malnutrition as a factor aggravating the heart failure course in the elderly and senile age

Cardiovascular diseases are the main death causes in the modern world. Heart failure (HF) is the terminal stage of most cardiovascular diseases. The prevalence of HF is increasing in patients of older age groups. At the same time, the number of geriatric syndromes increases with age, one of which is malnutrition. Recent studies demonstrate the mutually aggravating effect of heart failure and malnutrition, and that the correction of malnutrition can improve the heart failure course. The introduction of screening and timely correction of malnutrition will reduce the hospitalization and mortality rates in geriatric patients with HF

FARNESYL DIPHOSPHATE SYNTHASE (FDRS) AND GERANYLGERANYL DIPHOSPHATE SYNTHASE (GGSP1) GENE POLYMORPHISMS AND EFFICIENCY OF THERAPY WITH BISPHOSPHONATES IN RUSSIAN WOMEN WITH POSTMENOPAUSAL OSTEOPOROSIS: A PILOT STUDY

Genetic factors that are an important hereditary component determining a predisposition to osteoporosis (OP) are 60–80% responsible for bone mineral density (BMD). Some polymorphic genes have been previously shown to affect the efficiency of performed anti-osteoporotic therapy.Objective: to study the impact of farnesyl diphosphate synthase (FDRS) and geranylgeranyl diphosphate synthase (GGSPI) gene polymorphisms on BMD changes during 12-month therapy with bisphosphonates (BP) in women with postmenopausal OP.Subjects and methods. The investigation enrolled 53 women with OP. Spine and proximal femur BMD was determined using X-ray densitometry before and after BP treatment. The -99A/C and -8188T ins/del polymorphisms in the FDPS and GGPS1 genes were investigated using real-time polymerase chain reaction.Results and discussion. The BMD changes were less marked in women with the C allele of C/T -99/C polymorphism in the FDPS gene than those in carriers of the genotype AA: 2.3±3.6 and 4.4±3.8% (р = 0.062) in the spine; 0.6±3.1 and 2.8±4.5% (р = 0.075) in the femoral neck; 0.5±2.9 and 2.5±2.8% (р = 0.020) in the entire femur, respectively. Femoral neck densitometry showed a significantly weaker response to BP treatment in the patients carrying the mutant genotype del/del of GGSP1 -8188T ins/del polymorphism than in those with the wild-type genotype ins/ins (0.8±4.2 and 4.1±2.5%, respectively; р = 0.030). No significant differences for this polymorphism were found in other areas of BMD measurement.Conclusion. The described pilot study has indicated that the examined FDPS and GGSP1 gene polymorphisms may be predictors for a response to BP therapy in patients with OP. Further investigations that will contribute to the choice of the most effective therapy for this disease are needed to confirm our results