bluuebunny/crossref_metadata_2025 huggingface dataset:
A Practical Viscoplastic Damage Model for Lead-Free Solder
Authors: Fossum A. F. , Vianco P. T. , Neilsen M. K. , Pierce D. M.
Published: March 2006

This paper summarizes the results of a program to construct an internal variable viscoplastic damage model to characterize 95.5Sn–3.9Ag–0.6Cu (wt.%) lead-free solder under cyclic thermomechanical loading conditions. A unified model is enhanced to account for a deteriorating microstructure through the use of an isotropic damage evolution equation. Model predictions versus experimental data are given for constant strain-rate tests that were conducted at strain rates of 4.2×10−5s−1 and 8.3×10−4s−1 over a temperature range from −25°Cto160°C; cyclic shear tests; and elevated-temperature creep tests. A description is given of how this work supports larger ongoing efforts to develop a predictive capability in materials aging and reliability, and solder interconnect reliability.
Grain Size-Sensitive Creep in Ice II
Authors: Kubo Tomoaki , Durham William B. , Stern Laura A. , Kirby Stephen H.
Published: March 2006

Rheological experiments on fine-grained water ice II at low strain rates reveal a creep mechanism that dominates at conditions of low stress. Using cryogenic scanning electron microscopy, we observed that a change in stress exponent from 5 to 2.5 correlates strongly with a decrease in grain size from about 40 to 6 micrometers. The grain size–sensitive creep of ice II demonstrated here plausibly dominates plastic strain at the low-stress conditions in the interior of medium- to large-sized icy moons of the outer solar system.
Specificity of aVibrio vulnificusAminopeptidase toward Kinins and Other Peptidyl Substrates
Authors: Richards Gary P. , Nuñez Alberto
Published: March 2006

Recently, phosphoglucose isomerase with a lysyl aminopeptidase (PGI-LysAP) activity was identified inVibrio vulnificus. In this paper, we demonstrate the proteolytic cleavage of human-derived peptides by PGI-LysAP ofV. vulnificususing three approaches: (i) a quantitative fluorescent ninhydrin assay for free lysine, (ii) matrix-assisted laser desorption ionization-two-stage time of flight mass spectrometry (MALDI-TOF-TOF), and (iii) Tricine gel electrophoresis. PGI-LysAP hydrolyzed bradykinin, Lys-bradykinin, Lys-(des-Arg9)-bradykinin, neurokinin A, Met-Lys-bradykinin, histatin 8, and a myosin light chain fragment. We detected the proteolytic release of freel-lysine from peptide digests using a rapid, simple, sensitive, and quantitative fluorescent ninhydrin assay, and results were confirmed by MALDI-TOF-TOF. The use of the fluorescent ninhydrin assay to quantitatively detect free lysine hydrolyzed from peptides is the first application of its kind and serves as a paradigm for future studies. The visualization of peptide hydrolysis was accomplished by Tricine gel electrophoresis. Proteolytic processing of kinins alters their affinities toward specific cellular receptors and initiates signal transduction mechanisms responsible for inflammation, vasodilation, and enhanced vascular permeability. By applying novel approaches to determine the proteolytic potential of bacterial enzymes, we demonstrate that PGI-LysAP has broad exopeptidase activity which may enhanceV. vulnificusinvasiveness by altering peptides involved in signal transduction pathways.
Putative Surface Proteins Encoded within a Novel Transferable Locus Confer a High-Biofilm Phenotype to
Enterococcus faecalis
Authors: Tendolkar Preeti M. , Baghdayan Arto S. , Shankar Nathan
Published: March 2006

Enterococci are opportunistic pathogens and among the leading causes of nosocomial infections.
Enterococcus faecalis
, the dominant species among infection-derived isolates, has recently been recognized as capable of forming biofilms on abiotic surfaces in vitro as well as on indwelling medical devices. A few bacterial factors known to contribute to biofilm formation in
E. faecalis
have been characterized. To identify additional factors which may be important to this process, we utilized a Tn
917
-based insertional mutagenesis strategy to generate a mutant bank in a high-biofilm-forming
E. faecalis
strain, E99. The resulting mutant bank was screened for mutants exhibiting a significantly reduced ability to form biofilms. One mutant, P101D12, which showed greater than 70% reduction in its ability to form biofilms compared to the wild-type parent, was further characterized. The single Tn
917
insertion in P101D12 was mapped to a gene,
bee-2
, encoding a probable cell wall-anchored protein. Sequence information for the region flanking
bee-2
revealed that this gene was a member of a locus (termed the
bee
locus for
b
iofilm
e
nhancer in
e
nterococcus) comprised of five genes encoding three putative cell wall-anchored proteins and two probable sortases. Contour-clamped homogeneous electric field gel and Southern hybridization analyses suggested that the
bee
locus is likely harbored on a large conjugative plasmid. Filter mating assays using wild-type E99 or mutant P101D12 as a donor confirmed that the
bee
locus could transfer conjugally at high frequency to recipient
E. faecalis
strains. This represents the first instance of the identification of a mobile genetic element conferring biofilm-forming property in
E. faecalis
.
MotD of
Sinorhizobium meliloti
and Related α-Proteobacteria Is the Flagellar-Hook-Length Regulator and Therefore Reassigned as FliK
Authors: Eggenhofer Elke , Rachel Reinhard , Haslbeck Martin , Scharf Birgit
Published: March 2006

The flagella of the soil bacterium
Sinorhizobium meliloti
differ from the enterobacterial paradigm in the complex filament structure and modulation of the flagellar rotary speed. The mode of motility control in
S. meliloti
has a molecular corollary in two novel periplasmic motility proteins, MotC and MotE, that are present in addition to the ubiquitous MotA/MotB energizing proton channel. A fifth motility gene is located in the
mot
operon downstream of the
motB
and
motC
genes. Its gene product was originally designated MotD, a cytoplasmic motility protein having an unknown function. We report here reassignment of MotD as FliK, the regulator of flagellar hook length. The FliK gene is one of the few flagellar genes not annotated in the contiguous flagellar regulon of
S. meliloti
. Characteristic for its class, the 475-residue FliK protein contains a conserved, compactly folded Flg hook domain in its carboxy-terminal region. Deletion of
fliK
leads to formation of prolonged flagellar hooks (polyhooks) with missing filament structures. Extragenic suppressor mutations all mapped in the cytoplasmic region of the transmembrane export protein FlhB and restored assembly of a flagellar filament, and thus motility, in the presence of polyhooks. The structural properties of FliK are consistent with its function as a substrate specificity switch of the flagellar export apparatus for switching from rod/hook-type substrates to filament-type substrates.
Evidence that the Promoter Can Influence Assembly of Antitermination Complexes at Downstream RNA Sites
Authors: Zhou Ying , Shi Ting , Mozola Mark A. , Olson Eric R. , Henthorn Karla , Brown Susan , Gussin Gary N. , Friedman David I.
Published: March 2006

The N protein of phage λ acts with
Escherichia coli
Nus proteins at RNA sites, NUT, to modify RNA polymerase (RNAP) to a form that overrides transcription terminators. These interactions have been thought to be the primary determinants of the effectiveness of N-mediated antitermination. We present evidence that the associated promoter, in this case the λ early
P
R
promoter, can influence N-mediated modification of RNAP even though modification occurs at a site (NUTR) located downstream of the intervening
cro
gene. As predicted by genetic analysis and confirmed by in vivo transcription studies, a combination of two mutations in
P
R
, at positions −14 and −45 (yielding
P
R-GA
), reduces effectiveness of N modification, while an additional mutation at position −30 (yielding
P
R-GCA
) suppresses this effect. In vivo, the level of
P
R-GA
-directed transcription was twice as great as the wild-type level, while transcription directed by
P
R-GCA
was the same as that directed by the wild-type promoter. However, the rate of open complex formation at
P
R-GA
in vitro was roughly one-third the rate for wild-type
P
R
. We ascribe this apparent discrepancy to an effect of the mutations in
P
R-GCA
on promoter clearance. Based on the in vivo experiments, one plausible explanation for our results is that increased transcription can lead to a failure to form active antitermination complexes with NUT RNA, which, in turn, causes failure to read through downstream termination sites. By blocking antitermination and thus expression of late functions, the effect of increased transcription through
nut
sites could be physiologically important in maintaining proper regulation of gene expression early in phage development.
Photorhabdus
Virulence Cassettes Confer Injectable Insecticidal Activity against the Wax Moth
Authors: Yang G. , Dowling A. J. , Gerike U. , ffrench-Constant R. H. , Waterfield N. R.
Published: March 2006

Two recently sequenced genomes of the insect-pathogenic bacterium
Photorhabdus
and a large
Serratia entomophila
plasmid, pADAP, have phage-related loci containing putative toxin effector genes, designated the “
Photorhabdus
virulence cassettes” (PVCs). In
S. entomophila
, the single plasmid PVC confers antifeeding activity on larvae of a beetle. Here, we show that recombinant
Escherichia coli
expressing PVC-containing cosmids from
Photorhabdus
has injectable insecticidal activity against larvae of the wax moth. Electron microscopy showed that the structure of the PVC products is similar to the structure of the antibacterial R-type pyocins. However, unlike these bacteriocins, the PVC products of
Photorhabdus
have no demonstrable antibacterial activity. Instead, injection of
Photorhabdus
PVC products destroys insect hemocytes, which undergo dramatic actin cytoskeleton condensation. Comparison of the genomic organizations of several PVCs showed that they have a conserved phage-like structure with a variable number of putative anti-insect effectors encoded at one end. Expression of these putative effectors directly inside cultured cells showed that they are capable of rearranging the actin cytoskeleton. Together, these data show that the PVCs are functional homologs of the
S. entomophila
antifeeding genes and encode physical structures that resemble bacteriocins. This raises the interesting hypothesis that the PVC products are bacteriocin-like but that they have been modified to attack eukaryotic host cells.
The evaluation of the risks and benefits of phase II cancer clinical trials by institutional review board (IRB) members: a case study
Authors: van Luijn H E M , Aaronson N K , Keus R B , Musschenga A W
Published: February 2006

Objectives:There are indications that institutional review board (IRB) members do not find it easy to assess the risks and benefits in medical experiments, although this is their principal duty. This study examined how IRB members assessed the risk/benefit ratio (RBR) of a specific phase II breast cancer clinical trial.

Participants and methods:The trial was evaluated by means of a questionnaire administered to 43 members of IRBs at six academic hospitals and specialised cancer centres in the Netherlands. The questionnaire addressed: identification and estimation of inconvenience, toxicity, psychosocial distress, and benefits of trial participation to patients; identification and estimation of benefits to future patients and medical science; assessment of the trial’s RBR; and assessment of its ethical acceptability.

Results:Most IRB members expected trial participation to involve fairly or very serious inconvenience, fairly severe to sometimes life-threatening toxicity, and serious psychological and social consequences. Conversely, the perceived likelihood of benefits to patients was modest. Most regarded the study as important, and the balance between risks and benefits to be favourable, and believed that the protocol should be approved. The IRB members’ final judgement on the trial’s ethical acceptability was significantly correlated with their RBR assessment of the protocol.

Conclusions:Because most patients who participate in clinical trials hope this will prolong their lives, it is suggested that patient information should better describe the anticipated benefits—for example, the likelihood of prolonging life. This would allow patients to make decisions regarding participation based on realistic expectations.
Ethical issues in predictive genetic testing: a public health perspective
Authors: Fulda K G , Lykens K
Published: February 2006

As a result of the increase in genetic testing and the fear of discrimination by insurance companies, employers, and society as a result of genetic testing, the disciplines of ethics, public health, and genetics have converged. Whether relatives of someone with a positive predictive genetic test should be notified of the results and risks is a matter urgently in need of debate. Such a debate must encompass the moral and ethical obligations of the diagnosing physician and the patient. The decision to inform or not will vary depending on what moral theory is used. Utilising the utilitarian and libertarian theories produces different outcomes. The principles of justice and non-maleficence will also play an important role in the decision.
Concerns over confidentiality may deter adolescents from consulting their doctors. A qualitative exploration
Authors: Carlisle J , Shickle D , Cork M , McDonagh A
Published: February 2006

Objectives:Young people who are concerned that consultations may not remain confidential are reluctant to consult their doctors, especially about sensitive issues. This study sought to identify issues and concerns of adolescents, and their parents, in relation to confidentiality and teenagers’ personal health information.

Setting:Recruitment was conducted in paediatric dermatology and general surgery outpatient clinics, and on general surgery paediatric wards. Interviews were conducted in subjects’ own homes.

Methods:Semistructured interviews were used for this exploratory qualitative study. Interviews were carried out with 11 young women and nine young men aged 14–17. Parents of 18 of the young people were interviewed separately. Transcripts of tape recorded interviews provided the basis for a framework analysis.

Results:Young women were more concerned than young men, and older teenagers more concerned than younger teenagers, about people other than their general practitioner (GP) having access to their health information. Young people with little experience of the healthcare system were less happy than those with greater knowledge of the National Health Service (NHS) for non-medical staff to access their health information. As they grow older, adolescents become increasingly concerned that their health information should remain confidential.

Conclusion:Young people’s willingness to be open in consultations could be enhanced by doctors taking time to explain to them that their discussion is completely confidential. Alternatively, if for any reason confidentiality cannot be assured, doctors should explain why.
Stem cell research on other worlds, or why embryos do not have a right to life
Authors: Blackford R
Published: February 2006

Anxieties about the creation and destruction of human embryos for the purpose of scientific research on embryonic stem cells have given a new urgency to the question of whether embryos have moral rights. This article uses a thought experiment involving two possible worlds, somewhat removed from our own in the space of possibilities, to shed light on whether early embryos have such rights as a right not to be destroyed or discarded (a “right to life”). It is argued that early embryos do not have meaningful interests or any moral rights. Accordingly, claims about the moral rights of embryos do not justify restrictions on stem cell research.
Education of ethics committee members: experiences from Croatia
Authors: Borovečki A , ten Have H , Orešković S
Published: February 2006

Objectives:To study knowledge and attitudes of hospital ethics committee members at the first workshop for ethics committees in Croatia.

Design:Before/after cross-sectional study using a self administered questionnaire.

Setting:Educational workshop for members of hospital ethics committees, Zagreb, 2003.

Main outcome measurements:Knowledge and attitudes of participants before and after the workshop; everyday functioning of hospital ethics committees.

Results:The majority of the respondents came from committees with at least five members. The majority of ethics committees were appointed by the governing bodies of their hospitals. Most committees were founded after the implementation of the law on health protection in 1997. Membership structure (three physicians and two members from other fields) and functions were established on the basis of that law. Analysis of research protocols was the main part of their work. Other important functions—education, case analysis, guidelines formation—were neglected. Members’ level of knowledge was not sufficient for the complicated tasks they were supposed to perform. However, it was significantly higher after the workshop. Most respondents felt their knowledge should be improved by additional education. Their views on certain issues and bioethical dilemmas displayed a high level of paternalism and over protectiveness, which did not change after the workshop.

Conclusions:The committees developed according to bureaucratic requirements. Furthermore, there are concerns about members’ knowledge levels. More efforts need to be made to use education to improve the quality of the work. Additional research is necessary to explore ethics committees’ work in Croatia especially in the hospital setting.
Procreative beneficence and the prospective parent
Authors: Herissone-Kelly P
Published: February 2006

Julian Savulescu has given clear expression to a principle—that of “procreative beneficence”—which underlies the thought of many contemporary writers on bioethics. The principle of procreative beneficence (PPB) holds that parents or single reproducers are at least prima facie obliged to select the child, out of a range of possible children they might have, who will be likely to lead the best life. My aim in this paper is to argue that prospective parents, just by dint of their being prospective parents, are in fact not obliged to act on PPB. That is, there is something about their filling the role of prospective parents that exempts them from selecting the child with the best life. I urge that it is more realistic to view prospective parents as bound by a principle of acceptable outlook, which holds that they ought not to select children whose lives will contain an unacceptable amount of suffering.
The Groningen protocol: another perspective
Authors: Jotkowitz A B , Glick S
Published: February 2006

The Groningen protocol allows for the euthanasia of severely ill newborns with a hopeless prognosis and unbearable suffering. We understand the impetus for such a protocol but have moral and ethical concerns with it. Advocates for euthanasia in adults have relied on the concept of human autonomy, which is lacking in the case of infants. In addition, biases can potentially influence the decision making of both parents and physicians. It is also very difficult to weigh the element of quality of life on the will to live. We feel an important line has been crossed if the international medical community consents to the active euthanasia of severely ill infants and are concerned about the extension of the policy to other at risk groups.
Review of measurement instruments in clinical and research ethics, 1999–2003: Table 1
Authors: Redman B K
Published: February 2006

Every field of practice has the responsibility to evaluate its outcomes and to test its theories. Evidence of the underdevelopment of measurement instruments in bioethics suggests that attending to strengthening existing instruments and developing new ones will facilitate the interpretation of accumulating bodies of research as well as the making of clinical judgements. A review of 65 instruments reported in the published literature showed 10 with even a minimal level of psychometric data. Two newly developed instruments provide examples of the full use of psychometric and ethical theory. Bioethicists use a wide range of methods for knowledge development and verification; each method should meet stringent standards of quality.
Medical ethics manual: does it serve its purpose?
Authors: Nortvedt Per
Published: February 2006

World Medical Association.Ethics manual. Ferney-Voltaire: WMA, 2005.http://www.wma.net/e/ethicsunit/pdf/manual/ethics_manual.pdf(available for download). This manual of medical ethics is meant to serve the purpose of a guiding teaching aid for medical students as well as physicians. It was decided upon and planned by the World Medical Assembly in 1999 and the work was supervised and coordinated by the WMA Ethics Unit.
Teaching and assessing medical ethics: where are we now?
Authors: Mattick K , Bligh J
Published: February 2006

Objectives:To characterise UK undergraduate medical ethics curricula and to identify opportunities and threats to teaching and learning.

Design:Postal questionnaire survey of UK medical schools enquiring about teaching and assessment, including future perspectives.

Participants:The lead for teaching and learning at each medical school was invited to complete a questionnaire.

Results:Completed responses were received from 22/28 schools (79%). Seventeen respondents deemed their aims for ethics teaching to be successful. Twenty felt ethics should be learnt throughout the course and 13 said ethics teaching and learning should be fully integrated horizontally. Twenty felt variety in assessment was important and three tools was the preferred number. A shortfall in ethics core competencies did not preclude graduation in 15 schools. The most successful aspects of courses were perceived to be their integrated nature and the small group teaching; weaknesses were described as a need for still greater integration and the heavily theoretical aspects of ethics. The major concerns about how ethics would be taught in the future related to staffing and staff development.

Conclusions:This study describes how ethics was taught and assessed in 2004. The findings show that, although ethics now has an accepted place in the curriculum, more can be done to ensure that the recommended content is taught and assessed optimally.
Integrating catch-at-age and multiyear tagging data: a combined Brownie and Petersen estimation approach in a fishery context
Authors: Polacheck Tom , Eveson J Paige , Laslett Geoff M , Pollock Kenneth H , Hearn William S
Published: February 2006

A comprehensive framework for modelling data from multiyear tagging experiments in a fishery context is presented that incorporates catch data into the traditional Brownie tagrecapture model. Incorporation of catch data not only allows for improved estimation of natural and fishing mortality rates, but also for direct estimation of population size at the time of tagging. These are the primary quantities required to be estimated in stock assessments  having an approach for directly estimating them that does not require catch rates provides a potentially powerful alternative for augmenting traditional stock assessment methods. Simulations are used to demonstrate the value of directly incorporating catch data in the model. Results from the range of scenarios considered suggest that in addition to providing a precise estimate of population size (coefficients of variation ranging from ~15% to 30%), including catch data can decrease biases in the mortality rate estimates (natural mortality especially) and improve precision of fishing mortality rate estimates (by as much as 60% at age 1). The model is applied to southern bluefin tuna (Thunnus maccoyii) tagrecapture and catch data collected in the 1990s to provide estimates of natural mortality, fishing mortality, and abundance for five cohorts of fish.
Effects of reservoir connectivity on stream fish assemblages in the Great Plains
Authors: Falke Jeffrey A , Gido Keith B
Published: February 2006

The upstream effects of reservoirs on stream fish assemblages were highly localized in 3rd- through 5th-order streams in the Great Plains, USA. Streams that differed in connectivity to reservoirs were sampled at their confluences with a river or reservoir and between the confluence and the stream's origin. Sites at confluences had higher total, nonnative, and reservoir species richness than middle sites. Variability in fish assemblage structure upstream of reservoirs was influenced by catchment area, stream size, gradient, and reservoir connectivity. Confluence sites connected to reservoirs were correctly classified based on the presence of red shiners (Cyprinella lutrensis) and bluntnose minnows (Pimephales notatus) and the absence of sand shiners (Notropis stramineus); middle sites on connected streams were classified by the absence of redfin shiners (Lythrurus umbratilis). Intensive sampling across pool habitats within two streams isolated by a reservoir indicated that abundance of common reservoir species was related to pool size, turbidity, and canopy cover, but not proximity to the reservoir. These data suggest that streams connected to reservoirs can maintain diverse native fish communities with minimal invasions by reservoir-dwelling species, but a fraction of the community either has been lost or occurs at low abundance (e.g., sand shiners and redfin shiners).
Life history correlates of density-dependent recruitment in marine fishes
Authors: Goodwin Nicholas B , Grant Alastair , Perry Allison L , Dulvy Nicholas K , Reynolds John D
Published: February 2006

Understanding the relationships among life history traits, density dependence, and population dynamics is a central goal in ecology. It is also vital if we are to predict how populations respond to and recover from exploitation. We used data for 54 stocks of commercially exploited fish species to examine relationships between maximum annual recruitment at low stock size and the density dependence of recruitment at high stock size. We then related these recruitment measures to life history. At low stock sizes, stocks with high maximum recruitment (maximum spawners per spawner) showed the weakest density dependence of recruitment at high stock sizes. Spawning biomass per recruit in the absence of fishing (SPRF=0) showed a strong positive correlation with both maximum spawners per spawner and the strength of density dependence. Stocks with high SPRF=0 were typically large-bodied, slow-growing, late-maturing, and highly fecund with long generation times. These stocks produced low numbers of recruits each year, but survived to breed repeatedly and had strong density dependence of recruitment. In contrast, small-bodied, early-maturing fish had high annual recruitment and weak density dependence. These results place species on a continuum from "highly reproductive" to "survivors". But we also demonstrate that density dependence is an important feature of the population biology of survivors.
Spawning season fidelity in sympatric populations of Atlantic herring (Clupea harengus)
Authors: Brophy Deirdre , Danilowicz Bret S , King Pauline A
Published: February 2006

Considerable debate surrounds the issue of reproductive exchange between subunits of marine fish populations. Discrete population theories predict that spawning time and location are predetermined during larval life and that spawning season fidelity and natal homing maintain population integrity. Conversely, spawning assemblages may represent interconnected subgroups within metapopulations with social transmission of spawning behaviours facilitating mixing. This study examines spawning season fidelity in three subpopulations of Atlantic herring (Clupea harengus) with overlapping distributions. Autumn- and winter-spawned fish were collected from spawning and feeding grounds in the Irish and Celtic seas. Hatching season was determined using otolith microstructure and was compared with season of spawning as indicated by visual gonad inspection. Spawning assemblages in the Irish Sea consisted almost exclusively of autumn-spawned fish, despite extensive mixing with winter-spawned fish during the juvenile phase. The available evidence suggests that in Celtic herring, the season and location of spawning are not learned from repeat-spawning adults, but are predetermined, possibly through larval imprinting. The seasonal components showed distinct patterns of gonad development, and estimated rates of spawning season switching were below 10%. Although this exchange rate will facilitate some gene flow, mixing of subgroups is limited. This has important implications for management of seasonal spawning populations.
Surface bands on deepwater squalid dorsal-fin spines: an alternative method for ageing Centroselachus crepidater
Authors: Irvine Sarah B , Stevens John D , Laurenson Laurie JB
Published: February 2006

Bands on the external surface of the second dorsal-fin spine proved to be a novel method of estimating the age and growth of Centroselachus crepidater. Bands that followed the shape of the spine base were enhanced with an alizarin red derivative. Internal bands in spine cross sections were also examined. The number of both external and internal bands increased with animal size, although most spines had more external than internal bands. External bands were more reliable and were assumed to be annuli. The rate of band formation differed after five bands had been formed, and internal bands ceased forming after 30 years. Females to 54 years old and males to 34 years old were examined. Maturity occurred over a wide age range, with estimates of 20 years for females and 9 years for males. The youngest pregnant female was 27 years old. The Francis reparameterized von Bertalanffy growth model found similar growth for males and females, and the von Bertalanffy equations were Lt = 96.12(1  e(0.072(t+6.13))) for females and Lt = 73.22(1  e(0.141(t+2.99))) for males.
Improving the definition of fishing effort for important European fleets by accounting for the skipper effect
Authors: Marchal Paul , Andersen Bo , Bromley David , Iriondo Ane , Mahévas Stéphanie , Quirijns Floor , Rackham Brian , Santurtún Marina , Tien Nicola , Ulrich Clara
Published: February 2006

The scope of this paper is to quantify, for a wide selection of European fisheries, fishing tactics and strategies and to evaluate the benefits of adjusting the definition of fishing effort using these elements. Fishing tactics and strategies were identified by métiers choices and a series of indices. These indices have been derived to reflect shifts in tactics (within a fishing trip) and in strategies (within a year). The ShannonWiener spatial diversity indices of fishing tactics (FT_SW) and strategies (YE_SW) had the greatest impact on catch rates. In particular, FT_SW was always negatively correlated to catch rates. One may anticipate that during a fishing trip, vessels with high FT_SW have been searching fish aggregations for a long time, while vessels with low FT_SW have been more efficient in finding these aggregations. The linkage between YE_SW and catch rates was of a more complex nature. Adjusting fishing effort by means of (i) the métier effect and (ii) the indices of tactics and strategies generally led to a substantial gain in the precision of the relationship between fishing mortality and fishing effort.
Integrating marine protected areas with catch regulation
Authors: Hilborn Ray , Micheli Fiorenza , De Leo Giulio A
Published: February 2006

Previous models of marine protected areas (MPAs) have generally assumed that there were no existing regulations on catch and have frequently shown that MPAs, by themselves, can be used to maintain both sustainable fish stocks and sustainable harvests. We explore the impact of implementing an MPA in a spatially structured model of a single-species fish stock that is regulated by total allowable catch (TAC). We find that when a stock is managed at maximum sustainable yield, or is overfished, implementation of an MPA will require a reduction in TAC to avoid increased fishing pressure on the stock outside the MPA. In both cases, catches will be lower as a result of overlaying an MPA on existing fisheries management. Only when the stock is so overfished that it is headed towards extinction does an MPA not lead to lower catches. In a TAC-regulated fishery, even if the stock is overfished, MPA implementation may not improve overall stock abundance or increase harvest unless catch is simultaneously reduced in the areas outside the MPA. Models that consider differential adult and larval dispersal need to be explored to see if these results are found with the more complex biology of a two-stage model.
Modelling population viability in fragmented environments: contribution to the conservation of an endangered percid (Zingel asper)
Authors: Labonne Jacques , Gaudin Philippe
Published: February 2006

Zingel asper is an endemic percid of the Rhône catchment. The demography and habitat use of this endangered benthic species have been studied in previous works. The species exhibits natural low densities and clumped distribution related to habitat distribution. Based on these results, the authors build a stochastic equations network model, integrating spatial structure at intrapopulation level and vague density dependence. Calculation of density, growth rates, and local extinction rates globally match the field results. The numerical sensitivity analysis on extinction probabilities shows that adult and juvenile survival rates and spawning success (due to random events) are the key parameters of intrapatch dynamics. Low negative variations in these parameters increase extinction probabilities. The number of available connected patches and the dispersal rate drive the population persistence at the interpatch scale. Population extinction probability over 100 years is at least 0.4 for dispersal rate below 0.2, or when the number of connected patches is below 15. These results enlighten the role of dispersal in nonmigratory fish populations and should be useful in assessing the impact of riverine habitat fragmentation through river-damming and habitat loss.
Mechanisms of density dependence in stream fish: exploitation competition for food reduces growth of adult European bullheads (Cottus gobio)
Authors: Davey Andrew JH , Turner George F , Hawkins Stephen J , Doncaster C Patrick
Published: February 2006

In field experiments using cage enclosures, exploitation competition for invertebrate prey reduced individual growth of adult European bullheads (Cottus gobio) despite a dietary shift that maintained total prey biomass consumption. Growth of bullheads was negatively density dependent over a range of densities found in the field and total biomass production per enclosure was unrelated to stocking density. Individuals grew faster when invertebrate densities were experimentally elevated above ambient levels, indicating that bullheads were food limited. Parallel dietary shifts in response to manipulation of both bullhead density and resource availability suggested that exploitation competition for preferred Gammarus pulex prey was the primary cause of density-dependent growth. Switching to smaller prey species did not prevent growth of bullheads declining with increasing per capita food competition, indicating that the alternative prey were less profitable. Evidence for interference competition was limited. These results caution against the assumption that demographic rates of stream fish are density independent after the juvenile phase and demonstrate instead that density-dependent growth may potentially regulate populations at the adult stage via effects on fecundity and survival.
Factors influencing summer movement patterns of Bonneville cutthroat trout (Oncorhynchus clarkii utah)
Authors: Schrank Amy J , Rahel Frank J
Published: February 2006

We used multiple approaches to study summer movement patterns of Bonneville cutthroat trout (Oncorhynchus clarkii utah) in the Thomas Fork drainage of western Wyoming, USA. Our objectives were to (i) document summer movement patterns of cutthroat trout, especially as related to the concepts of local turnover and displacement distances, (ii) determine if fish size and condition were related to mobility, and (iii) compare summer movement patterns between years. Large fish (270384 mm total length) monitored by radiotelemetry showed little movement during the summer as evidenced by a maximum displacement distance of <300 m and a low turnover rate among locations (0.21). For a broad size range of fish marked with visual implant tags (173390 mm total length) in three study reaches, displacement distances were again low but turnover rate was high (>0.50 in most study reaches). This high turnover rate seemed to be driven mainly by movement among smaller fish as mobility declined with increasing fish size. Mobility also declined with decreasing body condition. Turnover rate in study reaches was higher during the summer of 1999 when stream flows were higher and water temperatures were cooler compared with the summer of 2000.
Effects of recreational and commercial fishing on blue sharks (Prionace glauca) in Atlantic Canada, with inferences on the North Atlantic population
Authors: Campana Steven E , Marks Linda , Joyce Warren , Kohler Nancy E
Published: February 2006

The nominal catch of blue sharks (Prionace glauca) reported for the Canadian Atlantic grossly underestimates the annual catch mortality of about 1000 tonnes (t), making blue sharks the most frequently caught large shark in Canadian waters. Although blue sharks accounted for 99% of all sharks landed at recreational shark fishing tournaments, tournament catches accounted for only 3% of total fishing mortality. Standardized catch rate indices suggested a decline in blue shark abundance of about 5%6%·year1 since 1995. An increased mortality rate in recent years was suggested by a decline in the median size of blue sharks in the commercial catch. Two independent calculations suggest that North Atlantic catches exceeded 100 000 t, with catch mortalities ranging between 26 000 and 37 000 t. Because tagging studies indicated that blue sharks are highly migratory with a single population in the North Atlantic, the Canadian contribution to overall population mortality accounts for only 2% of the total. The fact that blue shark populations are relatively productive and resilient may help explain their persistence in the face of high international catch mortality and a decline in relative abundance.
A field test verifies that pheromones can be useful for sea lamprey (Petromyzon marinus) control in the Great Lakes
Authors: Wagner C Michael , Jones Michael L , Twohey Michael B , Sorensen Peter W
Published: February 2006

Pheromone-baited traps have proven highly effective for managing insect pests by selectively removing reproductively active adults prior to mating. Here, we report a field test of two pheromones produced by the sea lamprey, Petromyzon marinus, which may be useful for controlling pest populations in the Laurentian Great Lakes. In the Trout River, Michigan, we demonstrated that (i) 90% of actively migrating sea lampreys could be drawn into streams treated with a migratory pheromone and (ii) lampreys were three times more likely to enter a barrier-integrated trap in a treated stream when pheromone was discharged directly through that trap (vs. an adjacent, unbaited trap). In a second experiment, we baited three traps with spermiating males (that are known to release a sex pheromone) to investigate how the quantity and spatial distribution of multiple pheromone signals would affect our ability to trap ovulating females. We found that mature females showed a strong tendency to select traps with multiple males over a trap with a single male when the signals were encountered simultaneously, but not when encountered sequentially. Our results strongly suggest pheromones may prove highly effective as attractants in trap-based management tactics for sea lamprey in the Great Lakes.
ENERGY DISTRIBUTION OF BLACK PLANE SOLUTIONS
Authors: HALPERN PAUL
Published: March 2006

We use the Einstein energy–momentum complex to calculate the energy distribution of static plane-symmetric solutions of the Einstein–Maxwell equations in 3+1 dimensions with asymptotic anti-de Sitter behavior. This solution is expressed in terms of three parameters: the mass, electric charge and cosmological constant. We compare the energy distribution to that of the Reissner–Nordström–anti-de Sitter solution, pointing to qualitative differences between the models. Finally, we examine these results within the context of the Cooperstock hypothesis.
A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly
Authors: Katsanos Christos S. , Kobayashi Hisamine , Sheffield-Moore Melinda , Aarsland Asle , Wolfe Robert R.
Published: February 2006

This study was designed to evaluate the effects of enriching an essential amino acid (EAA) mixture with leucine on muscle protein metabolism in elderly and young individuals. Four (2 elderly and 2 young) groups were studied before and after ingestion of 6.7 g of EAAs. EAAs were based on the composition of whey protein [26% leucine (26% Leu)] or were enriched in leucine [41% leucine (41% Leu)]. A primed, continuous infusion of l-[ ring-2H5]phenylalanine was used together with vastus lateralis muscle biopsies and leg arteriovenous blood samples for the determinations of fractional synthetic rate (FSR) and balance of muscle protein. FSR increased following amino acid ingestion in both the 26% (basal: 0.048 ± 0.005%/h; post-EAA: 0.063 ± 0.007%/h) and the 41% (basal: 0.036 ± 0.004%/h; post-EAA: 0.051 ± 0.007%/h) Leu young groups ( P < 0.05). In contrast, in the elderly, FSR did not increase following ingestion of 26% Leu EAA (basal: 0.044 ± 0.003%/h; post-EAA: 0.049 ± 0.006%/h; P > 0.05) but did increase following ingestion of 41% Leu EAA (basal: 0.038 ± 0.007%/h; post-EAA: 0.056 ± 0.008%/h; P < 0.05). Similar to the FSR responses, the mean response of muscle phenylalanine net balance, a reflection of muscle protein balance, was improved ( P < 0.05) in all groups, with the exception of the 26% Leu elderly group. We conclude that increasing the proportion of leucine in a mixture of EAA can reverse an attenuated response of muscle protein synthesis in elderly but does not result in further stimulation of muscle protein synthesis in young subjects.
Expression and function of potassium channels in the human placental vasculature
Authors: Wareing Mark , Bai Xilian , Seghier Fella , Turner Claire M. , Greenwood Susan L. , Baker Philip N. , Taggart Michael J. , Fyfe Gregor K.
Published: March 2006

In the placental vasculature, where oxygenation may be an important regulator of vascular reactivity, there is a paucity of data on the expression of potassium (K) channels, which are important mediators of vascular smooth muscle tone. We therefore addressed the expression and function of several K channel subtypes in human placentas. The expression of voltage-gated (Kv)2.1, KV9.3, large-conductance Ca2+-activated K channel (BKCa), inward-rectified K+ channel (KIR)6.1, and two-pore domain inwardly rectifying potassium channel-related acid-sensitive K channels (TASK)1 in chorionic plate arteries, veins, and placental homogenate was assessed by RT-PCR and Western blot analysis. Functional activity of K channels was assessed pharmacologically in small chorionic plate arteries and veins by wire myography using 4-aminopyridine, iberiotoxin, pinacidil, and anandamide. Experiments were performed at 20, 7, and 2% oxygen to assess the effect of oxygenation on the efficacy of K channel modulators. KV2.1, KV9.3, BKCa, KIR6.1, and TASK1 channels were all demonstrated to be expressed at the message level. KV2.1, BKCa, KIR6.1, and TASK1 were all demonstrated at the protein level. Pharmacological manipulation of voltage-gated and ATP-sensitive channels produced the most marked modifications in vascular tone, in both arteries and veins. We conclude that K channels play an important role in controlling placental vascular function.
Baroreflex mechanisms regulating mean level of SNA differ from those regulating the timing and entrainment of the sympathetic discharges in rabbits
Authors: Malpas Simon C. , Ramchandra Rohit , Guild Sarah-Jane , Budgett David M. , Barrett Carolyn J.
Published: March 2006

The arterial baroreflex pathway provides the fundamental basis for the short-term control of blood pressure via the rapid regulation of the mean level of sympathetic nerve activity (SNA) in response to changes in blood pressure. A central tenet in the generation and regulation of bursts of SNA is that input from the arterial baroreceptors also regulates the timing of the bursts of sympathetic activity. With the use of an implantable telemetry-based amplifier, renal SNA was recorded in intact and arterial baroreceptor-denervated (SAD) conscious rabbits. Data were collected continuously while animals were in their home cage. Mean levels of SNA were not different between SAD and baroreceptor-intact animals. Whereas SNA was unresponsive to changes in blood pressure in SAD rabbits, the timing of the bursts of SNA relative to the arterial pulse wave was maintained (time between the diastolic pressure and the next maximum SNA voltage averaged 107 ± 12 ms SAD vs. 105 ± 7 ms intact). Transfer function analysis between blood pressure and SNA indicates the average gain at the heart rate frequency was not altered by SAD, indicating strong coupling between the cardiac cycle and SNA bursts in SAD animals. Further experiments in anesthetized rabbits showed that this entrainment is lost immediately after performing baroreceptor denervation surgery and remained absent while the animal was under anesthesia but returned within 20 min of turning off the anesthesia. We propose that this finding indicates the regulation of the mean level of SNA requires the majority of input from baroreceptors to be functional; however, the regulation of the timing of the bursts in the conscious animal requires only minimal input, such as a sensitive trigger mechanism. This observation has important implications for understanding the origin and regulation of SNA.
Ovarian blood flow responses to electroacupuncture stimulation depend on estrous cycle and on site and frequency of stimulation in anesthetized rats
Authors: Stener-Victorin Elisabet , Fujisawa Shigeko , Kurosawa Mieko
Published: March 2006

Electroacupuncture (EA) applied to the abdomen and hindlimb modulates the ovarian blood flow (OBF) response. The present study aimed to further elucidate the role of the site and the frequency of short-term EA stimulation and the influence of the estrous cycle on the OBF response using anesthetized rats. EA stimulation was applied to the abdominal or the hindlimb muscles at three different frequencies (2, 10, and 80 Hz) during the estrus or diestrus phase. Involvement of spinal and supraspinal reflexes in OBF responses to EA stimulation was investigated by spinal cord transection. Abdominal EA stimulation at 10 Hz increased the OBF response, whereas hindlimb EA stimulation at 10 Hz and abdominal and hindlimb stimulation at 80 Hz decreased the OBF response; 2-Hz EA caused no OBF response. The OBF response to abdominal EA was more pronounced in the estrus than the diestrus phase. The OBF response to abdominal and hindlimb EA stimulation at both 10 and 80 Hz was almost abolished, both after severance of the sympathetic nerves and after spinal cord transection. In conclusion, the OBF response to both abdominal and hindlimb EA stimulation was mediated as a reflex response via the ovarian sympathetic nerves, and the response was controlled via supraspinal pathways. Furthermore, the OBF response to segmental abdominal EA stimulation was frequency dependent and amplified in the estrous phase.