Protein sliding and hopping kinetics on DNA

Using Monte-Carlo simulations, we deconvolved the sliding and hopping kinetics of GFP-LacI proteins on elongated DNA from their experimentally observed seconds-long diffusion trajectories. Our simulations suggest the following results: (1) in each diffusion trajectory, a protein makes on average hundreds of alternating slides and hops with a mean sliding time of several tens of ms; (2) sliding dominates the root mean square displacement of fast diffusion trajectories, whereas hopping dominates slow ones; (3) flow and variations in salt concentration have limited effects on hopping kinetics, while in vivo DNA configuration is not expected to influence sliding kinetics; furthermore, (4) the rate of occurrence for hops longer than 200 nm agrees with experimental data for EcoRV proteins

The Bereavement Guilt Scale:Development and preliminary validation

The rationale, development, and validation of the Bereavement Guilt Scale (BGS) are described in this article. The BGS was based on a theoretically developed, multidimensional conceptualization of guilt. Part 1 describes the generation of the item pool, derived from in-depth interviews, and review of the scientific literature. Part 2 details statistical analyses for further item selection (Sample 1, N = 273). Part 3 covers the psychometric properties of the emergent-BGS (Sample 2, N = 600, and Sample 3, N = 479). Confirmatory factor analysis indicated that a five-factor model fit the data best. Correlations of BGS scores with depression, anxiety, self-esteem, self-forgiveness, and mode of death were consistent with theoretical predictions, supporting the construct validity of the measure. The internal consistency and test-retest reliability were also supported. Thus, initial testing or examination suggests that the BGS is a valid tool to assess multiple components of bereavement guilt. Further psychometric testing across cultures is recommended

Shot noise in resonant tunneling through a zero-dimensional state with a complex energy spectrum

We investigate the noise properties of a GaAs/AlGaAs resonant tunneling structure at bias voltages where the current characteristic is determined by single electron tunneling. We discuss the suppression of the shot noise in the framework of a coupled two-state system. For large bias voltages we observed super-Poissonian shot noise up to values of the Fano factor $\alpha \approx 10$.Comment: 4 pages, 4 figures, accepted for Phys. Rev.

Predicting new superhard phases

The search for new superhard materials is of great importance in view of their major roles played for the fundamental science and the industrial applications. Recent experimental synthesis has made several great successes, but the synthetic difficulty in general remains. Materials design technique is greatly desirable as a request to assist experiment. In this paper, two rational theoretical methods of design of superhard materials have been reviewed: (i) substitutional method, which is successful in some cases, but limited to the known chemically related phases, and (ii) global free energy minimization method, which can be applied to large scale of materials with the only information of chemical compositions. The successful applications have been described and the main principles are summarized.Пошуки нових надтвердих матеріалів дуже важливі як з погляду їх ролі для фундаментальної науки, так і промислового застосування. Нещодавно було проведено декілька дуже успішних експериментів синтезу, однак труднощі синтезу загалом збереглися. Для допомоги в експериментах дуже потрібна техніка проектування матеріалів. У даній статті розглянуто два раціональні теоретичні методи дизайну надтвердих матеріалів: (1) метод заміщення, який є успішним у деяких випадках, але обмежується відомими хімічно спорідненими фазами, і (2) метод глобальної мінімізації вільної енергії, який може бути застосований до великої кількості матеріалів при наявності тільки інформації про хімічний склад.Поиски новых сверхтвердых материалов очень важны как с точки зрения их роли для фундаментальной науки, так и промышленного применения. Недавно было проведено несколько очень успешных экспериментов синтеза, однако трудности синтеза в общем сохранились. Для помощи в экспериментах нужна техника проектирования материалов. В данной статье рассмотрены два рациональных теоретических метода дизайна сверхтвердых материалов: (1) метод замещения, который является успешным в некоторых случаях, но ограничивается известными химически родственными фазами, и (2) метод глобальной минимизации свободной энергии, который может быть применен к большому количеству материалов при наличии только информации о химических составах

Quasi-Periodic Releases of Streamer Blobs and Velocity Variability of the Slow Solar Wind near the Sun

We search for persistent and quasi-periodic release events of streamer blobs during 2007 with the Large Angle Spectrometric Coronagraph on the \textit{Solar and Heliospheric Observatory} and assess the velocity of the slow solar wind along the plasma sheet above the corresponding streamer by measuring the dynamic parameters of blobs. We find 10 quasi-periodic release events of streamer blobs lasting for three to four days. In each day of these events, we observe three-five blobs. The results are in line with previous studies using data observed near the last solar minimum. Using the measured blob velocity as a proxy for that of the mean flow, we suggest that the velocity of the background slow solar wind near the Sun can vary significantly within a few hours. This provides an observational manifestation of the large velocity variability of the slow solar wind near the Sun.Comment: 14 pages, 5 figures, accepted by Soalr Physic

Measurement of Trace I-129 Concentrations in CsI Powder and Organic Liquid Scintillator with Accelerator Mass Spectrometry

Levels of trace radiopurity in active detector materials is a subject of major concern in low-background experiments. Procedures were devised to measure trace concentrations of I-129 in the inorganic salt CsI as well as in organic liquid scintillator with Accelerator Mass Spectrometry (AMS) which leads to improvement in sensitivities by several orders of magnitude over other methods. No evidence of their existence in these materials were observed. Limits of < 6 X 10^{-13} g/g and < 2.6 X 10^{-17} g/g on the contaminations of I-129 in CsI and liquid scintillator, respectively, were derived.These are the first results in a research program whose goals are to develop techniques to measure trace radioactivity in detector materials by AMS.Comment: Proceedings of 10th International Conference on Accelerator Mass Spectrometr