Feeding and egg production of Oithona similis in the North Atlantic

Although cyclopoids of the genus Oithona are considered the most abundant copepods in the marine environment, there is still very little information about what sustains their population and almost constant reproduction rate throughout the year. Feeding and egg production rate (EPR) of O. similis were measured at coastal and oceanic stations during 3 cruises in the North Atlantic between April and November 2002. O. similis ingested ciliates preferentially to other components of the nano- and microplankton (herein nano-microplankton), which only became a more important component of the copepod diet when the abundance of the former decreased to low concentrations. EPR did not show significant seasonal differences, with 2.13 ± 0.67 eggs female–1 d–1 in spring, 1.61 ± 0.32 eggs female–1 d–1 in summer and 1.60 ± 0.15 eggs female–1 d–1 in winter. The ingestion rates measured at many oceanic stations and in winter were often too low to sustain EPR. Egg production efficiency (GGE) >100% indicated that sustained EPR might have relied, particularly in winter, on alternative food sources such as a more carnivorous diet and/or on the faecal pellets of euphausids

Predicting function from sequence in a large multifunctional toxin family

Venoms contain active substances with highly specific physiological effects and are increasingly being used as sources of novel diagnostic, research and treatment tools for human disease. Experimental characterisation of individual toxin activities is a severe rate-limiting step in the discovery process, and in-silico tools which allow function to be predicted from sequence information are essential. Toxins are typically members of large multifunctional families of structurally similar proteins that can have different biological activities, and minor sequence divergence can have significant consequences. Thus, existing predictive tools tend to have low accuracy. We investigated a classification model based on physico-chemical attributes that can easily be calculated from amino-acid sequences, using over 250 (mostly novel) viperid phospholipase A2 toxins. We also clustered proteins by sequence profiles, and carried out in-vitro tests for four major activities on a selection of isolated novel toxins, or crude venoms known to contain them. The majority of detected activities were consistent with predictions, in contrast to poor performance of a number of tested existing predictive methods. Our results provide a framework for comparison of active sites among different functional sub-groups of toxins that will allow a more targeted approach for identification of potential drug leads in the future

Evaluation and validation of Damage Assessment Tracking Criteria models within the sector of UK automotive remanufacturing

This paper details the specific aims and purposes of the Damage Assessment Tracking Criteria; a series of evaluation tools designed to aid in remanufacturing inspection operations. The background and justification of this model, which is detailed in a separate work, identifies ill definition and an over reliance on opinion as barriers to effective inspection activities. Analysis of this issue led to the building of the Damage Assessment Tracking Criteria; a 4-model foundation that aims to provide a more comprehensive and more structured approach to the inspection stages of the typical remanufacturing process. Through expert opinion this model was evaluated multiple times. One review was used to gauge the level of idea communication within an academic situation, this was followed up by external industrial reviews of the model by those most likely to utilise it during industry practice. After extensive feedback and modification the final model assessment was carried out with an expert panel that were instructed to be as critical as possible with the model in order to ensure that its evaluation was as robust as possible. The results of these reviews were all on the positive side of the scale. Multiple statements regarding the potential value and suitability of each model aspect and justification for their use was presented in the format of an evaluation form which was used by those involved to present their findings and feedback. Negative feedback was addressed and successful modification yielding more positive results in the next evaluation was achieved. Though walking the line between specificity and generic was noted to be the most difficult factor to consider when developing the models, the final findings of the evaluation show that significant value was perceived by those operating within industry. The potential benefits of customised variants of the models is acknowledged by all parties as a possible future avenue of research

Bottom quark electroproduction in variable flavor number schemes

Two variable flavor number schemes are used to describe bottom quark production in deep inelastic electron-proton scattering. In these schemes the coefficient functions are derived from mass factorization of the heavy quark coefficient functions presented in a fixed flavor number scheme. Also one has to construct a parton density set with five light flavors (u,d,s,c,b) out of a set which only contains four light flavors (u,d,s,c). In order $\alpha_s^2$ the two sets are discontinuous at $\mu=m_b$ which follows from mass factorization of the heavy quark coefficient functions when it is carried out in the ${\bar {\rm MS}}$-scheme. Both variable flavor number schemes give almost identical predictions for the bottom structure functions $F_{2,b}$ and $F_{L,b}$. Also they both agree well with the corresponding results based on fixed order four-flavor perturbation theory over a wide range in $x$ and $Q^2$.Comment: Latex with seventeen PostScript figure

Genome-wide analyses of Liberibacter species provides insights into evolution, phylogenetic relationships, and virulence factors.

'Candidatus Liberibacter' species are insect-transmitted, phloem-limited α-Proteobacteria in the order of Rhizobiales. The citrus industry is facing significant challenges due to huanglongbing, associated with infection from 'Candidatus Liberibacter asiaticus' (Las). In order to gain greater insight into 'Ca. Liberibacter' biology and genetic diversity, we have performed genome sequencing and comparative analyses of diverse 'Ca. Liberibacter' species, including those that can infect citrus. Our phylogenetic analysis differentiates 'Ca. Liberibacter' species and Rhizobiales in separate clades and suggests stepwise evolution from a common ancestor splitting first into nonpathogenic Liberibacter crescens followed by diversification of pathogenic 'Ca. Liberibacter' species. Further analysis of Las genomes from different geographical locations revealed diversity among isolates from the United States. Our phylogenetic study also indicates multiple Las introduction events in California and spread of the pathogen from Florida to Texas. Texan Las isolates were closely related, while Florida and Asian isolates exhibited the most genetic variation. We have identified conserved Sec translocon (SEC)-dependent effectors likely involved in bacterial survival and virulence of Las and analysed their expression in their plant host (citrus) and insect vector (Diaphorina citri). Individual SEC-dependent effectors exhibited differential expression patterns between host and vector, indicating that Las uses its effector repertoire to differentially modulate diverse organisms. Collectively, this work provides insights into the evolution of 'Ca. Liberibacter' species, the introduction of Las in the United States and identifies promising Las targets for disease management

Charm Contribution to the Structure Function in Diffractive Deep Inelastic Scattering

The charm contribution to the structure functions of diffractive deep inelastic scattering is considered here within the context of the Ingelman-Schlein model. Numerical estimations of this contribution are made from parametrizations of the HERA data. Influence of the Pomeron flux factor is analized as well as the effect of the shape of the initial parton distribution employed in the calculations. The obtained results indicate that the charm contribution to diffractive deep inelastic process might be large enough to be measured in the HERA experiments.Comment: 16 pages, RevTeX, 6 figures, to be published in Physical Review

Fully differential W' production and decay at next-to-leading order in QCD

We present the fully differential production and decay of a W' boson, with arbitrary vector and axial-vector couplings, to any final state at next-to-leading order in QCD. We demonstrate a complete factorization of couplings at next-to-leading order in both the partial width of the W' boson, and in the full two-to-two cross section. We provide numerical predictions for the contribution of a W' boson to single-top-quark production, and separate results based on whether the mass of the right-handed neutrino (nu_R) is light enough for the leptonic decay channel to be open. The single-top-quark analysis will allow for an improved direct W' mass limit of 525-550 GeV using data from run I of the Fermilab Tevatron. We propose a modified tolerance method for estimating parton distribution function uncertainties in cross sections.Comment: 23 pages, revtex3, 13 ps fig

Comparison between variable flavor number schemes for charm quark electroproduction

Where appropriate, the abbreviation 'VFNS' is replaced by 'CSN' to indicate the scheme using massive heavy quark coefficient functions proposed in this paper. The text below Eq. (2.13) and between Eqs. (2.33) and (2.36) has been considerably changed.Comment: 64 pages, LaTeX, 16 Postscript figure

Quasi-stationary regime of a branching random walk in presence of an absorbing wall

A branching random walk in presence of an absorbing wall moving at a constant velocity $v$ undergoes a phase transition as the velocity $v$ of the wall varies. Below the critical velocity $v_c$, the population has a non-zero survival probability and when the population survives its size grows exponentially. We investigate the histories of the population conditioned on having a single survivor at some final time $T$. We study the quasi-stationary regime for $v<v_c$ when $T$ is large. To do so, one can construct a modified stochastic process which is equivalent to the original process conditioned on having a single survivor at final time $T$. We then use this construction to show that the properties of the quasi-stationary regime are universal when $v\to v_c$. We also solve exactly a simple version of the problem, the exponential model, for which the study of the quasi-stationary regime can be reduced to the analysis of a single one-dimensional map.Comment: 2 figures, minor corrections, one reference adde