Elucidating Diphosphoinositol Polyphosphate Function with Nonhydrolyzable Analogues

The diphosphoinositol polyphosphates (PP‐IPs) represent a novel class of high‐energy phosphate‐containing messengers which control a wide variety of cellular processes. It is thought that PP‐IPs exert their pleiotropic effects as allosteric regulators and through pyrophosphorylation of protein substrates. However, most details of PP‐IP signaling have remained elusive because of a paucity of suitable tools. We describe the synthesis of PP‐IP bisphosphonate analogues (PCP‐IPs), which are resistant to chemical and biochemical degradation. While the two regioisomers 1PCP‐IP₅ and 5PCP‐IP₅ inhibited Akt phosphorylation with similar potencies, 1PCP‐IP₅ was much more effective at inhibiting its cognate phosphatase hDIPP1. Furthermore, the PCP analogues inhibit protein pyrophosphorylation because of their inability to transfer the β‐phosphoryl group, and thus enable the distinction between PP‐IP signaling mechanisms. As such, the PCP analogues will find widespread applications for the structural and biochemical characterization of PP‐IP signaling properties.     

Detecting a conditional extreme value model

In classical extreme value theory probabilities of extreme events are estimated assuming all the components of a random vector to be in a domain of attraction of an extreme value distribution. In contrast, the conditional extreme value model assumes a domain of attraction condition on a sub-collection of the components of a multivariate random vector. This model has been studied in Heffernan and Tawn (JRSS B 66(3):497–546, 2004), Heffernan and Resnick (Ann Appl Probab 17(2):537–571, 2007), and Das and Resnick (2009). In this paper we propose three statistics which act as tools to detect this model in a bivariate set-up. In addition, the proposed statistics also help to distinguish between two forms of the limit measure that is obtained in the model.     

Images of unstable Taylor-Sedov blast waves propagating through auniform gas

We present images from the first observation and measurements of an instability in Taylor-Sedov blast waves propagating through a uniform background gas. The instability occurs when the adiabatic index of the background gas is low. Images of the expanding blast waves are dark field shadowgraphs obtained using a frequency-doubled (527 nm) pulsed YAG laser and black and white photographic film. The film images are digitized, and image processing routines are used for analysis and presentation     

Modern Trends in Physics Research. Third International Conference on Modern Trends in Physics Research. Cairo,Egypt 6–10 April 2008, edited by Lotfia M. El Nadi

The reaction power densities for the important nuclear fusion reactions are compared with the radiation losses due to Bremsstrahlung and cyclotron radiation. Some properties of an ionized plasma and the particle motions in such a plasma are discussed and methods of containing a plasma within magnetic confining fields are described. The present ideas on the stability of such confining fields, resulting from several theoretical studies, are outlined, and various means of heating the plasma are discussed. The main features of the experimental devices disclosed at Geneva in 1958 are compared, and the leading experimental results reported at the 1959 I.E.E. Convention on Thermonuclear Processes are reviewed.     

Femtosecond Laser–Matter Interactions: Theory,Experiments, and Applications,by Eugene G. Gamaly

The Mössbauer effect, the recoilless absorption and emission of gamma rays by nuclei embedded in solids, has its origin in the properties of the solid state. The nature of this connection is dealt with in some detail and the various effects of the crystalline environment on the nuclear energy levels is described. The importance of these effects as contributions to the study of the physical and chemical properties of crystals is discussed, and applications which depend on the intrinsic energy resolution of the effect are described. The recoilless nuclear resonant scattering and diffraction of gamma rays is also dealt with in some detail.     

Determination of the impurity concentration in heavily doped inhomogeneous semiconductors from the measurement of the low-temperature conductivity

A method has been developed for determining the effective concentration of shallow impuritiesN ^* reponsible for the low-temperature conductivity in the vicinity of the metal-insulator transition for inhomogeneous samples of n-Ge:As. The method is based on the measurement of two ratios of sample resistance -R(4.2 K)/R(300 K), =R(2.0 K)/R(4.2 K) and the conductivity (4.2 K). The next step consists of plotting and (4.2) vs . Assuming that is the most reliable parameter, one can calculate, after an averaging procedare, the corrected values of ^*, ^*(4.2) and the resistivity at room temperature ^*(300)=[ ^{* *}(4.2)]^–1. Finally, using the known dependence (300)=f(N) for homogeneous samples, one can obtain the values ofN ^*. The dependences ofN ^* on and on are plotted. The scaling behavior of the conductivity of the Ge:As samples with corrected values of ^*(4.2) andN ^* has been observed down toT=100 mK.     

Ratios of ordered points of point processes with regularly varying intensity measures

We study limiting properties of ratios of ordered points of point processes whose intensity measures have regularly varying tails, giving a systematic treatment which points the way to “large-trimming” properties of extremal processes and a variety of applications. Our point process approach facilitates a connection with the negative binomial process of Gregoire (1984) and consequently to certain generalised versions of the Poisson–Dirichlet distribution.