Statistical properties of multistep enzyme-mediated reactions

Enzyme-mediated reactions may proceed through multiple intermediate conformational states before creating a final product molecule, and one often wishes to identify such intermediate structures from observations of the product creation. In this paper, we address this problem by solving the chemical master equations for various enzymatic reactions. We devise a perturbation theory analogous to that used in quantum mechanics that allows us to determine the first () and the second (variance) cumulants of the distribution of created product molecules as a function of the substrate concentration and the kinetic rates of the intermediate processes. The mean product flux V=d/dt (or "dose-response" curve) and the Fano factor F=variance/ are both realistically measurable quantities, and while the mean flux can often appear the same for different reaction types, the Fano factor can be quite different. This suggests both qualitative and quantitative ways to discriminate between different reaction schemes, and we explore this possibility in the context of four sample multistep enzymatic reactions. We argue that measuring both the mean flux and the Fano factor can not only discriminate between reaction types, but can also provide some detailed information about the internal, unobserved kinetic rates, and this can be done without measuring single-molecule transition events.Comment: 8 pages, 3 figure

Correlations of Specific Ionic Effects using Ion Channels and Surface Charge Measurements

poster abstractSpecific ionic effects, as captured in the Hofmeister series, have been observed in many biological phenomena including protein folding and aggregation and lipid bilayer interactions. Previously we have shown that the Hofmeister effect is present in the activity of gramicidin A channels. In particular, measurements of channel open lifetime and conductance in potassium salts clearly show the existence of two distinct ionic classes that could be identified as kosmotropic and chaotropic. To further investigate this behavior, we have measured the zeta potential of diphytanoyl phosphatidylcholine (DPhPC) liposomes in salt solutions. We observe that anions alter the surface charge of the liposomes depending on the classification of the anion as kosmotropic or chaotropic. Chaotropic anions (SCN-, ClO4-) decrease the surface charge of the liposomes while kosmotropic anions (Cl-, H2PO4-, SO42-) have the opposite effect. These results correlate with our previous studies of cation conductance through gramicidin A channels adding new insight into ionic interactions at the lipid-water interface

PROBLEMS AND PROSPECTS FOR THE DEVELOPMENT OF WIND ENERGY

В данной статье рассмотрены перспективы и проблемы развития ветроэнергетики. Показаны разные виды ветроустановок с концетраторами. Выявлены плюсы и минусы ветрогенераторов с концетраторами ветровой энергии.This article considers the prospects and problems of wind power development. Different types of wind installations with terminators are also considered. The advantages and disadvantages of wind generators with wind energy terminators have been identified

ЭТАПЫ СОЦИАЛЬНОЙ АДАПТАЦИИ: ФИЛОСОФСКИЕ АСПЕКТЫ

The article explores the process of social personal adaptation. The research is aimed at structuring the process of social adaptation for further formation of general methodology of research and formation of the mechanism of its management in specific conditions. The authors pose that specific features of adaptation as special ontologic form of personal life are expressed in hetero ontologic character that assumes three parts: natural, psychological and social. The authors represent definition of social adaptation reviewed as a process of solving the contradiction that arises between personality and society and results in development and socialization by means of experience received. The authors highlight the main components of the structure of social adaptation process as follows: adaptation resources (adaptability), adaptive behavior and adjustment. The main criteria of adaptability are defined as cognitive, axio-cultural, communicative and behavioural ones. The paper outlines the strategies of adaptive behavior: active, passive and active and passive. It is shown that constructive vigorous adaptive activity always assumes personal growth and development through expansion and increase of level of search, informative activity, mobilization of all adaptive resources on a solution. The authors describe subjective and objective criteria of adjustment caused by adaptation process. The demarcation of concepts of adaptability, adaptive behavior and adjustment allows to avoid semantic confusion and substitution of concepts of research practice of scientists. Structuring of adaptation process allows applying new methodology and the new ways of the mechanism of precision management of social adaptation.В статье рассматривается процесс социальной адаптации личности. Цель работы заключалась в осуществлении структуризации процесса социальной адаптации для последующего формирования единой методологии исследования и формирования механизма управления этим процессом в конкретных условиях жизнедеятельности. Авторы утверждают, что специфика адаптации как особой онтологической формы бытия человека выражается в ее гетероонтологическом характере, предполагающем наличие трех качественно различных, но взаимосвязанных сторон: природной, психологической и социальной. Предлагается определение социальной адаптации как процесса разрешения личностью противоречия, возникающего между ней и обществом в процессе жизнедеятельности, результатом чего является развитие и становление личности за счет прибавки получаемого в ходе решения противоречия опыта. Авторами было определено, что основными компонентами структуры социального адаптационного процесса являются следующие специфические концепты: адаптационные ресурсы (адаптивность), адаптивное поведение, адаптированность. Определены основные критерии адаптивности: когнитивный, аксиокультурный, коммуникативный, поведенческий. Выделены стратегии адаптивного поведения: активная, пассивная и активно-пассивная. Показано, что конструктивная активная адаптивная деятельность – это всегда личностный рост и развитие через расширение и повышение уровня поисковой, познавательной активности, мобилизации всех адаптивных ресурсов на решение проблемы. Описаны субъективные и объективные критерии адаптированности как результата адаптационного процесса. Осуществленная демаркация понятий адаптивности, адаптивного поведения, адаптированности позволяет избегать семантической путаницы и подмены понятий в научно-исследовательской практике ученых, а структуризация адаптационного процесса позволяет наметить новую методологию и новые направления построения механизма точечного управления социальной адаптацией

Polymers pushing Polymers: Polymer Mixtures in Thermodynamic Equilibrium with a Pore

We investigate polymer partitioning from polymer mixtures into nanometer size cavities by formulating an equation of state for a binary polymer mixture assuming that only one (smaller) of the two polymer components can penetrate the cavity. Deriving the partitioning equilibrium equations and solving them numerically allows us to introduce the concept of "polymers-pushing-polymers" for the action of non-penetrating polymers on the partitioning of the penetrating polymers. Polymer partitioning into a pore even within a very simple model of a binary polymer mixture is shown to depend in a complicated way on the composition of the polymer mixture and/or the pore-penetration penalty. This can lead to enhanced as well as diminished partitioning, due to two separate energy scales that we analyse in detail.Comment: 10 pages, 6 figure

Measurement of the J/Psi Production Cross Section in 920 GeV/c Fixed-Target Proton-Nucleus Interactions

The mid-rapidity (dsigma_(pN)/dy at y=0) and total sigma_(pN) production cross sections of J/Psi mesons are measured in proton-nucleus interactions. Data collected by the HERA-B experiment in interactions of 920 GeV/c protons with carbon, titanium and tungsten targets are used for this analysis. The J/Psi mesons are reconstructed by their decay into lepton pairs. The total production cross section obtained is sigma_(pN)(J/Psi) = 663 +- 74 +- 46 nb/nucleon. In addition, our result is compared with previous measurements

Determination of the muon charge sign with the dipolar spectrometers of the OPERA experiment

The OPERA long-baseline neutrino-oscillation experiment has observed the direct appearance of $\nu_\tau$ in the CNGS $\nu_\mu$ beam. Two large muon magnetic spectrometers are used to identify muons produced in the $\tau$ leptonic decay and in $\nu_\mu^{CC}$ interactions by measuring their charge and momentum. Besides the kinematic analysis of the $\tau$ decays, background resulting from the decay of charmed particles produced in $\nu_\mu^{CC}$ interactions is reduced by efficiently identifying the muon track. A new method for the charge sign determination has been applied, via a weighted angular matching of the straight track-segments reconstructed in the different parts of the dipole magnets. Results obtained for Monte Carlo and real data are presented. Comparison with a method where no matching is used shows a significant reduction of up to 40\% of the fraction of wrongly determined charges.Comment: 10 pages. Improvements in the tex

Emulsion sheet doublets as interface trackers for the OPERA experiment

New methods for efficient and unambiguous interconnection between electronic counters and target units based on nuclear photographic emulsion films have been developed. The application to the OPERA experiment, that aims at detecting oscillations between mu neutrino and tau neutrino in the CNGS neutrino beam, is reported in this paper. In order to reduce background due to latent tracks collected before installation in the detector, on-site large-scale treatments of the emulsions ("refreshing") have been applied. Changeable Sheet (CSd) packages, each made of a doublet of emulsion films, have been designed, assembled and coupled to the OPERA target units ("ECC bricks"). A device has been built to print X-ray spots for accurate interconnection both within the CSd and between the CSd and the related ECC brick. Sample emulsion films have been extensively scanned with state-of-the-art automated optical microscopes. Efficient track-matching and powerful background rejection have been achieved in tests with electronically tagged penetrating muons. Further improvement of in-doublet film alignment was obtained by matching the pattern of low-energy electron tracks. The commissioning of the overall OPERA alignment procedure is in progress.Comment: 19 pages, 19 figure

The detection of neutrino interactions in the emulsion/lead target of the OPERA experiment

The OPERA neutrino detector in the underground Gran Sasso Laboratory (LNGS) was designed to perform the first detection of neutrino oscillations in appearance mode through the study of $\nu_\mu\to\nu_\tau$ oscillations. The apparatus consists of an emulsion/lead target complemented by electronic detectors and it is placed in the high energy long-baseline CERN to LNGS beam (CNGS) 730 km away from the neutrino source. Runs with CNGS neutrinos were successfully carried out in 2007 and 2008 with the detector fully operational with its related facilities for the emulsion handling and analysis. After a brief description of the beam and of the experimental setup we report on the collection, reconstruction and analysis procedures of first samples of neutrino interaction events

Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR

Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At LHC and top RHIC energies, QCD matter is studied at very high temperatures and nearly vanishing net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was created at experiments at RHIC and LHC. The transition from the QGP back to the hadron gas is found to be a smooth cross over. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure, such as a first-order phase transition between hadronic and partonic matter which terminates in a critical point, or exotic phases like quarkyonic matter. The discovery of these landmarks would be a breakthrough in our understanding of the strong interaction and is therefore in the focus of various high-energy heavy-ion research programs. The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD matter: the phase structure at large baryon-chemical potentials (mu_B > 500 MeV), effects of chiral symmetry, and the equation-of-state at high density as it is expected to occur in the core of neutron stars. In this article, we review the motivation for and the physics programme of CBM, including activities before the start of data taking in 2022, in the context of the worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal