Universality of Persistence Exponents in Two-Dimensional Ostwald Ripening

We measured persistence exponents θ ( ϕ ) of Ostwald ripening in two dimensions, as a function of the area fraction ϕ occupied by coarsening domains. The values of θ ( ϕ ) in two systems, succinonitrile and brine, quenched to their liquid-solid coexistence region, compare well with one another, providing compelling evidence for the universality of the one-parameter family of exponents. For small ϕ , θ ( ϕ ) ≃ 0.39 ϕ , as predicted by a model that assumes no correlations between evolving domains. These constitute the first measurements of persistence exponents in the case of phase transitions with a conserved order parameter

Toward the evaluation of the influence of temperature fluctuations on the durability of the stator winding insulation of asynchronous motors in random mode loading

В статье обсуждается влияние колебаний температуры обмотки электродвигателя на скорость старения изоляции обмотки статора асинхронного двигателя при работе в случайных режимах нагружения. Показано, что при определенных параметрах случайного режима работы срок службы изоляции может существенно снижаться, при этом широко используемый для оценки теплового состояния двигателя метод средних потерь дает оценку теплового состояния двигателя с существенной ошибкой.The influence of the stator winding temperature oscillation on the insulation-aging rate of the asynchronous motors stator winding in random mode loading. It is shown that under certain parameters of the random mode insulation durability can significantly decrease, wherein the widely used average loss method gives the evaluation of the motor thermal state with a substantial error.дна строка 10 pt

The mathematical simulation of dc-dc coverter in the frequency-controlled electric drive with ultracapacitors

В статье рассматриваются вопросы построения математической модели силовой части DCDC преобразователя, который используется для подключения суперконденсаторов в звено постоянного тока частотно-регулируемого электропривода. Рассматривается принцип действия DC-DC преобразователя, режимы его работы, приводятся уравнения и структурная схема для описания силовой части преобразователя в составе частотно-регулируемого электропривода. В заключительной части статьи приводятся результаты моделирования.The article deals with a mathematical model of the power part of the DC-DC converter, which is used to connect the supercapacitors into the DC link of frequency-controlled electric drive. The operating principle and boost and buck modes of the DC-DC converter are considered. The functional diagram and equations for power part of DC-DC converter as a part of frequency-controlled electric drive are described. The final part of the article presents the simulations results

PHOTOCHEMISTRY OF PHYCOBILIPROTEINS

Native PEC from the cyanobacterium, Mastigocladus laminosus, and its isolated α-subunit show photoreversibly photochromic reactions with difference-maxima around 502 and 570 nm in the spectral region of the α-84 phycoviolobilin chromophore. (b) Native PEC and its β-subunit show little if any reversible photochemistry in the 600–620 nm region, where the phycocyanobilin chromophores on the β-subunit absorb maximally, (c) Reversible photochemistry is retained in ureadenatured PEC at pH = 7.0 or pH ≤ 3. The difference maxima are shifted to 510 and 600 nm, and the amplitudes are decreased. An irreversible absorbance increase occurs around 670 nm (pH ≤ 3). (d) The amplitude of the reversible photoreaction difference spectrum is maximum in the presence of 4–5 M urea or 1 M KSCN, conditions known to dissociate phycobiliprotein aggregates into monomers. At the same time, the phycocyanobilin chromophore(s) are bleached irreversibly, (e) The amplitude becomes very small in high aggregates, e.g. in phycobilisomes. (f) In a reciprocal manner, the phototransformation of native PEC leads to a reversible shift of its aggregation equilibrium between trimer and monomer. The latter is favored by orange, the former by green light, (g) It is concluded that the phycoviolobilin chromophore of PEC is responsible for reversible photochemistry in PEC, and that there is not only an influence of aggregation state on photochemistry, but also vice versa an effect of the status of the chromophore on aggregation state. This could constitute a primary signal in the putative function as sensory pigment, either directly, or indirectly via the release of other polypeptides, via photodynamic effects, or the like

Simcluster: clustering enumeration gene expression data on the simplex space

Transcript enumeration methods such as SAGE, MPSS, and sequencing-by-synthesis EST "digital northern", are important high-throughput techniques for digital gene expression measurement. As other counting or voting processes, these measurements constitute compositional data exhibiting properties particular to the simplex space where the summation of the components is constrained. These properties are not present on regular Euclidean spaces, on which hybridization-based microarray data is often modeled. Therefore, pattern recognition methods commonly used for microarray data analysis may be non-informative for the data generated by transcript enumeration techniques since they ignore certain fundamental properties of this space.

Here we present a software tool, Simcluster, designed to perform clustering analysis for data on the simplex space. We present Simcluster as a stand-alone command-line C package and as a user-friendly on-line tool. Both versions are available at: http://xerad.systemsbiology.net/simcluster.

Simcluster is designed in accordance with a well-established mathematical framework for compositional data analysis, which provides principled procedures for dealing with the simplex space, and is thus applicable in a number of contexts, including enumeration-based gene expression data

REVERSIBLE DC-DC CONVERTER AS ENERGY-SAVING FREQUENCYVERIABLE DRIVE WITH STORAGE SYSTEM ELEMENT

The article deals with a reversible DC-DC designing as energy–saving fvd with storage system element.The functional diagrams for power part of DC-DC converter as a part of frequency-controlled electric drive are described. The final part of the article presents the simulations results.В статье рассматриваются вопросы построения реверсивного DC-DC преобразователя как элемента энергосберегающего электропривода с системой хранения энергии. Приводятся структурные схемы для описания силовой части DC-DC преобразователя в составе частотно-регулируемого электропривода. В заключительной части статьи приводятся результаты моделирования

Single-molecule experiments in biological physics: methods and applications

I review single-molecule experiments (SME) in biological physics. Recent technological developments have provided the tools to design and build scientific instruments of high enough sensitivity and precision to manipulate and visualize individual molecules and measure microscopic forces. Using SME it is possible to: manipulate molecules one at a time and measure distributions describing molecular properties; characterize the kinetics of biomolecular reactions and; detect molecular intermediates. SME provide the additional information about thermodynamics and kinetics of biomolecular processes. This complements information obtained in traditional bulk assays. In SME it is also possible to measure small energies and detect large Brownian deviations in biomolecular reactions, thereby offering new methods and systems to scrutinize the basic foundations of statistical mechanics. This review is written at a very introductory level emphasizing the importance of SME to scientists interested in knowing the common playground of ideas and the interdisciplinary topics accessible by these techniques. The review discusses SME from an experimental perspective, first exposing the most common experimental methodologies and later presenting various molecular systems where such techniques have been applied. I briefly discuss experimental techniques such as atomic-force microscopy (AFM), laser optical tweezers (LOT), magnetic tweezers (MT), biomembrane force probe (BFP) and single-molecule fluorescence (SMF). I then present several applications of SME to the study of nucleic acids (DNA, RNA and DNA condensation), proteins (protein-protein interactions, protein folding and molecular motors). Finally, I discuss applications of SME to the study of the nonequilibrium thermodynamics of small systems and the experimental verification of fluctuation theorems. I conclude with a discussion of open questions and future perspectives.Comment: Latex, 60 pages, 12 figures, Topical Review for J. Phys. C (Cond. Matt

Photochemistry and photophysics of thienocarbazoles

Two methylated thienocarbazoles and two of their synthetic nitro-precursors have been examined by absorption, luminescence, laser flash photolysis and photoacoustic techniques. Their spectroscopic and photophysical characterization involves fluorescence spectra, fluorescence quantum yields and lifetimes, and phosphorescence spectra and phosphorescence lifetimes for all the compounds. Triplet-singlet difference absorption spectra, triplet molar absorption coefficients, triplet lifetimes, intersystem crossing S-1 similar tosimilar to--> T-1 and singlet molecular oxygen yields were obtained for the thienocarbazoles. In the case of the thienocarbazoles it was found that the lowest-lying singlet and triplet excited states, S, and T-1, are of pi,pi* origin, whereas for their precursors S-1 is n,pi*, and T-1 is pi,pi*. In both thienocarbazoles it appears that the thianaphthene ring dictates the S, T, yield, albeit there is less predominance of that ring in the triplet state of the linear thienocarbazole, which leads to a decrease in the observed Phi(T) value.info:eu-repo/semantics/publishedVersio

Analysis of genetic systems using experimental evolution and whole-genome sequencing

The application of whole-genome sequencing to the study of microbial evolution promises to reveal the complex functional networks of mutations that underlie adaptation. A recent study of parallel evolution in populations of Escherichia coli shows how adaptation involves both functional changes to specific proteins as well as global changes in regulation