The inelastic mean free path of electrons. Past and present research

The inelastic mean free path (IMFP) is a fundamental material parameter. Presently the IMFPs calculated by the TPP-2M predictive formula (NIST SRD 71) are generally used. Elastic peak electron spectroscopy (EPES) is proved to be adequate for experimental determination of the IMFP denoted by λ_e. λ_e is smaller then λ_i (TPP-2M) values, due to surface losses, characterized by the SEP (surface excitation) P_se material parameter. The present research is focused on the experimental determination of P_se based on Tanuma's work. The Tanuma factor f_sT is the ratio of experimental I_e and calculated I_c elastic peak intensities I_e(E)/I_c(E). The detection angle dependent I_c is proportional to ΔΩ, the solid angle of detection. The angular I_c(E,ΔΩ,α_d) was calculated applying the EPESWIN software of Jablonski. In our work, experimental data of Goto were analysed for Si and Ni. Recent angularly resolved AREPES results of Jablonski and Zemek were quantified by fitting them at the 42° CMA (cylindrical mirror analyser) angle to absolute data of Goto and applying f_sT. The models and SEP material parameters published by Werner et al., Ding et al., Kwei et al., Jablonski-Zemek and Nagatomi-Goto (Ni) and our data obtained by modifying Chen's data (Si) have been tested. The best approach was obtained using data of Werner for Si, and data of Nagatomi for Ni. The SEP corrected IMFPs λ_eco were deduced. The EPES SEP parameters were valid for AREPES by averaging over α_d = 35-70°. EPES spectra are quantified by applying the backscattering yield.     

Comparison of planktonic and reed biofilm bacteria in different riverine water bodies of river Danube

As the submerged shoot parts of common reed (Phragmites australis) can provide large surfaces for biofilm‐forming bacteria, extensive reed stands can effectively contribute to the self‐purification in the littoral zones of freshwaters. However, bacterial biofilm developed on reed surfaces have been studied only in still waters. In the present study, comparative examinations were performed on the planktonic and reed biofilm bacterial communities from two different riverine water bodies. Water and reed biofilm samples were taken at the beginning and end of the vegetation period from (a) a regulated side arm and (b) a separated oxbow of River Danube. Besides measuring physical and chemical environmental variables, planktonic bacterial cell numbers were detected by 4′,6‐diamidino‐2‐phenylindole staining method, and the bacterial communities were compared by denaturing gradient gel electrophoresis. Our results demonstrated that the structure and composition of bacterial communities correlated with different environmental variables and were different regarding both the habitats (planktonic vs. reed biofilm) and the types of riverine water bodies. The seasonal differences in the bacterial community structures were smaller in the river side arm than in the separated oxbow. In the water column, representatives of widespread and typical freshwater planktonic bacteria (“Candidatus Planktophila,” Limnohabitans, and Polynucleobacter), whereas, in the reed biofilm samples, phototrophic and plant associated bacteria were identified.     

Protecting the consistency of workflow applications in collaborative development environments

Collaborative development environments allow a group of users to view and edit a shared item from geographically dispersed sites. Consistency maintenance in the face of concurrent accesses to shared entities is one of the core issues in the design of these systems. The paper introduces a lock based solution and three different algorithms that enable controlled, concurrent access to workflows for multiple application developers. Collaborative development of workflow applications promises better outcome in shorter time. The described method ensures that collaborators cannot break the consistency criteria of workflows by adding cycles or invalid edges to the graphs. A formal analysis of the three graph locking algorithms is also provided, focusing on the number of users who are allowed to edit a single workflow simultaneously. Based on the findings, a more powerful fourth graph locking algorithm is defined.     

Towards efficient decision rules for admission control based on the many sources asymptotics

This paper introduces new admission criteria that enable the use of algorithms based on the many sources asymptotics in real-life applications. This is achieved by a significant reduction in the computational requirements and by moving the computationally intensive tasks away from the timing-sensitive decision instant. It is shown that the traditional overflow probability type admission control method can be reformulated into a bandwidth requirement type and into a buffer requirement type method and that these methods are equivalent when used for admission control. The original and the two proposed methods are compared through the example of fractional Brownian motion (fBm) traffic.     

Inferring the outcome of an ongoing novel action at 13 months.

Many studies have demonstrated that infants can attribute goals to observed actions, whether they are presented live by familiar agents or on a computer screen by abstract figures. However, because most, if not all, of these studies rely on the repeated action presentations typical of infant studies, it is not clear whether infants are simply recognizing the completed action as goal directed, or whether they can productively infer a not-yet-achieved outcome from an ongoing action. We investigated this question by presenting 13-month-old infants with a single animated chasing event. Infants looked longer at the outcome of this action when, given the opportunity, the chaser did not catch the chasee than when it did. Crucially, this result was dependent on whether the action could be construed as efficient with regard to this goal state. This finding suggests the ability to infer the goal of an ongoing novel action and illustrates the productivity of 1-year-olds’ action understanding. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Research needs for design of concrete containment structures

Potential failure modes of reinforced concrete containment shells are outlined, especially those associated with pressure-induced cracking and seismic forces. A summary is given of experimental and analytical research needed to evaluate tangential shear capacity and stiffness, the interaction between liner and cracked concrete, peripheral (punching) shear capacity, radial shear behavior, and nonlinear dynamic analysis approaches.     

Peripheral shear strength of biaxially tensioned reinforced concrete wall elements

The results of a series of tests on biaxially tensioned, orthogonally reinforced concrete panels subjected to punching shear are presented and discussed. Contrary to existing U.S. code provisions, the punching shear capacity is not reduced significantly as the biaxial tension level is increased to as much as 0.8f_y in the reinforcement. A design equation is proposed that gives 4√f′_c shear stress for zero biaxial tension and a linear decrease to 3.1√f′_c as the tension is increased to 0.9f_y.The size of the loading pad under the punching force and the shear span have little effect on the strength but the pattern of the failure crack does change with these geometric variables. The splitting crack tends to connect the edge of the loading pad and the supports.More testing is recommended to evaluate a few additional variables, such as the use of inserts which receive the punching force.     

Excitation-contraction coupling--cardiac muscle events in the myofilament

The interaction of myosin and actin is by intracellular Ca2+ concentration, which in turn is controlled by the sarcoplasmic reticulum. In muscle--including cardiac muscle--of vertebrates, and some invertebrates, the site of Ca2+ control is in the thin, actin-containing filaments. These filaments contain tropomyosin and troponin; the latter is a complex of three subunits. When Ca2+ combines with troponin C, the Ca-binding subunit, a shift occurs in the position of tropomyosin that makes it possible for the myosin heads to bind to actin. This process is inhibited by a conformational change in troponin C, resulting in the release of the troponin complex from one of the binding sites on the thin filament. This process exhibits cooperative aspects which have been analyzed in terms of the Ca-binding process and the effect of Ca2+ on actomyosin ATPase activity.     

Functional analysis of the Neurospora crassa PZL-1 protein phosphatase by expression in budding and fission yeast

The gene pzl-1 from the filamentous fungus Neurospora crassa encodes a putative Ser/Thr protein phosphatase that is reminiscent of the Ppz1/Ppz2 and Pzh1 phosphatases from Saccharomyces cerevisiae and Schizosaccharomyces pombe, respectively. The entire PZL-1 protein, as well as its carboxyl-terminal domain, have been expressed in Escherichia coli as active protein phosphatases. To characterize its cellular role, PZL-1 was also expressed in Sz. pombe and in S. cerevisiae. Expression of PZL-1 in S. cerevisiae from the PPZ1 promoter was able to rescue the altered sensitivity to caffeine and lithium ions of a ppz1 strain. Furthermore, high copy number expression of PZL-1 alleviated the lytic phenotype of a S. cerevisiae slt2/mpk1 mitogen-activated protein (MAP) kinase mutant, similarly to that described for PPZ1, and mimicked the effects of high levels of Ppz1 on cell growth. Expression of PZL-1 in fission yeast from a weak version of the nmt1 promoter fully rescued the growth defect of a pzh1Delta strain in high potassium, but only partially complemented the sodium-hypertolerant phenotype. Strong overexpression of the N. crassa phosphatase in Sz. pombe affected cell growth and morphology. Therefore, PZL-1 appears to fulfil every known function carried out by its S. cerevisiae counterpart, despite the marked divergence in sequence within their NH(2)-terminal moieties.     

Testing, Analysis, and Evaluation of a GFRP Deck on Steel Girders

North Carolina has recently installed a fiber-reinforced polymer (FRP) deck on steel girders at a site in Union County. The bridge was instrumented with foil strain gauges, strain transducers, and displacement transducers. The bridge was then tested with a simulated MS-22.5 design load. Experimental data confirmed full composite interaction between the girders and the FRP deck panels. The neutral axis was measured to be 383?mm above the bottom flange of the 618-mm-deep girder. It was found that composite action could be estimated within 3% using a transformed section analysis of the deck panels. For two lanes loaded, the maximum live load distribution factor was computed to be 0.75. When looking at the overall performance of the structure, the deck deflected 5?mm, with the allowable stress at least 10 times over the maximum stress measured in the material. The girder deflection of 7?mm was well within the parameters set forth by AASHTO. Simple span deflection equations were found to conservatively model the anticipated deflection of the girders when using the transformed section properties.