bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Hybrid Method to Predict the Convergence History of Aeroelastic Calculations of Mistuned/Tuned Bladed Disks
Authors: He Zhijiang , Epureanu Bogdan I. , Pierre Christophe
Published: July 2008

Mistuning changes the dynamics of bladed disks significantly. Consequently, frequency domain methods for predicting the dynamics of mistuned bladed disks are typically based on iterative aeroelastic calculations. Converged aerodynamic matrices are required for accurate aeroelastic results of eigenvalue and forced response problems. The tremendous computation time needed for each aerodynamic iteration would greatly benefit from a fast method of predicting the number of iterations needed for converged results. A new hybrid technique is proposed to predict the convergence history based on several critical ratios and by approximating as linear the relation between the aerodynamic force and the complex frequencies (eigenvalues) of the system. The new technique is hybrid in that it uses a combined theoretical and stochastic/computational approach. The dynamics of an industrial bladed disk is investigated, and the predicted convergence histories are shown to match the actual results very well. Monte Carlo simulations using the new approach show that the aerodynamic ratio and the aerodynamic gradient ratio are important factors affecting the convergence history.
Vortex-Induced Vibrations of a Rigid Cylinder on Non-Linear Elastic Supports
Authors: Bourdier S. , Chaplin J. R.
Published: July 2008

The dynamics of vortex-induced vibrations of a rigid circular cylinder with structural non-linearities, introduced by means of discontinuities in the support system, are studied experimentally. The analysis of the measurements is carried out using non-linear vibration tools, i.e phase-flow portraits, frequency spectra, Lyapunov exponents and correlation dimensions, to provide an insight into the dynamical changes in the system brought about by restricting the motion. We show that chaotic motions can occur due to the structural non-linearities.
A New Method for Determining the Eigenmodes of Finite Flow-Structure Systems
Authors: Lucey Anthony D. , Pitman Mark W.
Published: July 2008

A new method for directly determining the eigenmodes of finite flow-structure systems is presented, using the classical problem of the interaction of a uniform flow with a flexible panel, held at both ends, as an exemplar. The method is a hybrid of theoretical analysis and computational modelling. This new approach is contrasted with the standard Galerkin method that is most often used to study the hydro-elasticity of finite systems. Unlike the Galerkin method, the new method does not require an a priori approximation of perturbations via a finite sum of modes. Instead, the coupled equations for the wall-flow system are cast, using computational methods that, in this exemplar, combine boundary-element and finite-element methods, to yield a single matrix equation for the system that is a second-order differential equation for the panel-displacement variable. Standard state-space methods are then used to extract the eigenmodes of the system directly. We present definitive results for the stability of the case of an unsupported flexible plate, elucidating its divergence and flutter characteristics, and the effect of energy dissipation in the structure. Finally, we present some results for the case of a spring-backed flexible plate that illustrate the complicated dynamics of this type of wall; these dynamics would be poorly modelled by a traditional Galerkin method.
Instability of a Cantilevered Flexible Plate in Inviscid Channel Flow
Authors: Howell Richard M. , Lucey Anthony D. , Carpenter Peter W.
Published: July 2008

A novel method for calculating the linear fluid-structure interaction of a cantilevered flexible plate centrally positioned in ideal channel flow, incorporating the effects of vorticity shed downstream, is described. When the channel walls are moved far apart, predictions of the critical velocity show good correlation with other published work. For the first time, detailed numerical investigation of the effect on this fluid-structure interaction of channel walls, a rigid central surface (upstream and adjacent to the flexible plate), unsteady mean flow and the variation of stiffness and damping properties along the flexible plate have been quantified. Of central importance is the application of the unsteady model to the investigation of the human snoring phenomenon. Further insight into the operation of two types of snore is made and a new type of snore is discovered that originates from the time-dependent effects of inhalation.
Vibrations of Circular Cylindrical Shells With Complex Boundary Conditions
Authors: Pellicano Francesco
Published: July 2008

In the present paper vibrations of circular cylindrical shells having different boundary conditions are analyzed. Sanders-Koiter theory is considered for shell modeling: both linear and nonlinear vibrations are analyzed. An energy approach based on Lagrange equations is considered; a mixed expansion of displacement fields, based on harmonic functions and Tchebyshev polynomials, is applied. Several boundary conditions are analyzed: simply supported, clamped-clamped, connection with rigid bodies. Comparisons with experiments and finite element analyses show that the technique is capable to model several and complex boundary conditions. Applications to geometrically nonlinear shells show that the technique is effective also in the case of nonlinear vibration: comparisons with the literature confirm the accuracy of the approach.
Effect of Bubbles on Flow Induced Vibration
Authors: Pelletier Angela R. , McKelvey Ian A. , Katz Joseph
Published: July 2008

The effects of a turbulent, bubbly boundary layer on wall skin friction have been investigated in numerous previous studies. However, the impact of such a multiphase flow on fluid-structure interactions has not been studied. To this end, the present project examines experimentally the effect of a bubbly boundary layer on the vibration of a vertical plate. Using a combination of accelerometers and pressure transducers, we simultaneously measure the plate vibrations and wall pressure fluctuations for varying flow rates, gas void fractions, and characteristic bubble sizes. The results show that the presence of bubbles substantially increases both the plate vibrations and the wall pressure fluctuations. The vibrations increase by up to 20 dB compared to the same flow without bubbles. The spectra of vibrations become broad and vary significantly with the characteristic bubble size. The variations with bubble size are consistent with the resonant frequency of the bubbles, indicating that, in addition to changing the compressibility of the medium, individual bubbles act at sources.
Wind Tunnel Test and Wind Effects on Cable Dome
Authors: Zhang Zhi-hong , Tamura Yukio
Published: July 2008

This paper presents preliminary results of an aeroelastic wind tunnel test on a cable dome. The structural design of the model is given in detail. Similarity requirements based on dimensional analysis are discussed, including Froude number, Cauchy number and Scruton number. Structural tests are conducted on the aeroelastic model. Dynamic instability subject to harmonic excitation like SDOF hardening system is verified. Both odd and even frequency components are excited when the shaking table dowels at 29Hz. For the one-degree-of-freedom Duffing model, even frequency components will be impossible due to the symmetry of the motion equation if symmetry-breaking bifurcation behaviors do not occur. Phase plane is checked and discussed when the shaking table dowels at 7Hz. A strange attractor is found from Poincare map. Some statistical results of wind tunnel tests are presented. The possibility of aeroelasic instability of the cable dome is discussed.
Numerical Study of a Tube Bundle Vibrations in Cross-Flows: ALE and Transpiration Methods
Authors: de Morais Marcus Vinicius G. , Gibert Rene-Jean , Baj Franck , Magnaud Jean-Paul
Published: July 2008

In this paper, we compare the performances of ALE and Transpiration methods. The ALE approach is a powerful tool to treat coupled problems. We can mention for ALE, more precisely, the approach in finite elements of Donea and Hughes. However, the ALE performance for determining fluid-elastic forces to small vibration amplitudes is still ignored. The Transpiration method is a simplified approach for calculating fluid-elastic forces to relatively small vibration amplitudes. Based on a first order development of velocity boundary conditions, this method allows the use of a fluid domain fixed in time during a dynamic computation, by avoiding the problems due to the mesh distortions. The purpose of this work is to provide a numerical estimate of the critical flow velocity for the threshold of fluid-elastic instability of tube bundle without experimental investigation. A staggered coupled numerical approach is suggested and applied to the numerical prediction of the vibration frequency of a flexible tube belonging to a fixed tube bundle in fluid flow. Numerical results turn out to be consistent with available experimental data obtained in the same configuration. This work presents our numerical results for a prediction of tube bundle vibrations induced by flows implemented in CAST3M, a numerical platform of French Nuclear Agency (CEA-Saclay).
The Metamorphosis of Supernova SN 2008D/XRF 080109: A Link Between Supernovae and GRBs/Hypernovae
Authors: Mazzali Paolo A. , Valenti Stefano , Della Valle Massimo , Chincarini Guido , Sauer Daniel N. , Benetti Stefano , Pian Elena , Piran Tsvi , D'Elia Valerio , Elias-Rosa Nancy , Margutti Raffaella , Pasotti Francesco , Antonelli L. Angelo , Bufano Filomena , Campana Sergio , Cappellaro Enrico , Covino Stefano , D'Avanzo Paolo , Fiore Fabrizio , Fugazza Dino , Gilmozzi Roberto , Hunter Deborah , Maguire Kate , Maiorano Elisabetta , Marziani Paola , Masetti Nicola , Mirabel Felix , Navasardyan Hripsime , Nomoto Ken'ichi , Palazzi Eliana , Pastorello Andrea , Panagia Nino , Pellizza L. J. , Sari Re'em , Smartt Stephen , Tagliaferri Gianpiero , Tanaka Masaomi , Taubenberger Stefan , Tominaga Nozomu , Trundle Carrie , Turatto Massimo
Published: July 2008

The only supernovae (SNe) to show gamma-ray bursts (GRBs) or early x-ray emission thus far are overenergetic, broad-lined type Ic SNe (hypernovae, HNe). Recently, SN 2008D has shown several unusual features: (i) weak x-ray flash (XRF), (ii) an early, narrow optical peak, (iii) disappearance of the broad lines typical of SN Ic HNe, and (iv) development of helium lines as in SNe Ib. Detailed analysis shows that SN 2008D was not a normal supernova: Its explosion energy (
E
â 6Ã10
51
erg) and ejected mass [â¼7 times the mass of the Sun (

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)] are intermediate between normal SNe Ibc and HNe. We conclude that SN 2008D was originally a â¼30

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star. When it collapsed, a black hole formed and a weak, mildly relativistic jet was produced, which caused the XRF. SN 2008D is probably among the weakest explosions that produce relativistic jets. Inner engine activity appears to be present whenever massive stars collapse to black holes.
Ceftibuten Resistance and Treatment Failure ofNeisseria gonorrhoeaeInfection
Authors: Lo Janice Y. C. , Ho K. M. , Leung Anna O. C. , Tiu Felisa S. T. , Tsang Grand K. L. , Lo Angus C. T. , Tapsall John W.
Published: July 2008

Neisseria gonorrhoeaeinfections have been empirically treated in Hong Kong with a single oral 400-mg dose of ceftibuten since 1997. Following anecdotal reports of the treatment failure of gonorrhea with oral extended-spectrum cephalosporins, the current study was undertaken to determine the antimicrobial susceptibility pattern and molecular characteristics of isolates ofN. gonorrhoeaeamong patients with putative treatment failure in a sexually transmitted disease clinic setting. Between October 2006 and August 2007, 44 isolates ofN. gonorrhoeaewere studied from patients identified clinically to have treatment failure with empirical ceftibuten. The ceftibuten MICs for three strains were found to have been 8 mg/liter. These strains were determined byN. gonorrhoeaemultiantigen sequence typing to belong to sequence type 835 (ST835) or the closely related ST2469. The testing of an additional eight archived ST835 strains revealed similarly elevated ceftibuten MICs. ThepenAgene sequences of these 11 isolates all had the mosaic pattern previously described as pattern X. Of note is that the ceftriaxone susceptibility results of these strains all fell within the susceptible range. It is concluded that ceftibuten resistance may contribute to the empirical treatment failure of gonorrhea caused by strains harboring the mosaicpenAgene, which confers reduced susceptibility to oral extended-spectrum cephalosporins. Screening for such resistance in the routine clinical laboratory may be undertaken by the disk diffusion test. The continued monitoring of antimicrobial resistance and molecular characteristics ofN. gonorrhoeaeisolates is important to ensure that control and prevention strategies remain effective.
Mutator Genes Giving Rise to Decreased Antibiotic Susceptibility in
Pseudomonas aeruginosa
Authors: Wiegand Irith , Marr Alexandra K. , Breidenstein Elena B. M. , Schurek Kristen N. , Taylor Patrick , Hancock Robert E. W.
Published: July 2008

Screening of the PA14 genomic transposon mutant library for resistance to ceftazidime, tobramycin, and ciprofloxacin led to the discovery of several mutants that appeared in more than one screen. Testing of the frequency of mutation to ciprofloxacin resistance revealed previously known mutator genes, including
mutS
and
mutL
, as well as mutators that have not yet been described for
P. aeruginosa
, including PA3958 and RadA (PA4609).
CYP56 (Dit2p) in
Candida albicans
: Characterization and Investigation of Its Role in Growth and Antifungal Drug Susceptibility
Authors: Melo N. R. , Moran G. P. , Warrilow A. G. S. , Dudley E. , Smith S. N. , Sullivan D. J. , Lamb D. C. , Kelly D. E. , Coleman D. C. , Kelly S. L.
Published: July 2008

The complete DNA sequence of
Candida albicans DIT2
, encoding cytochrome P450 family 56 (CYP56), was obtained, and heterologous expression was achieved in
Escherichia coli
, where CYP56 was targeted to the membrane fraction. In reconstituted assays with the purified enzyme, CYP56 was shown to catalyze the conversion of
N
-formyl tyrosine into
N
,
N
′-bisformyl dityrosine, a reaction that was dependent on cytochrome P450 reductase, NADPH, and oxygen, yielding a turnover of 21.6 min
−1
and a

k
s

of 26 μM. The Hill number was calculated as 1.6, indicating that two molecules of the substrate could bind to the protein. Azole antifungals could bind to the heme of CYP56 as a sixth ligand with high affinity. Both chromosomal alleles of
CYP56
were disrupted using the
SAT1
flipper technique, and
CYP56
was found to be nonessential for cell viability under the culture conditions investigated. Susceptibility to azole drugs that bind to cytochromes P450 was tested, and the mutant showed unaltered susceptibility. However, the mutant showed increased susceptibility to the echinocandin drug caspofungin, suggesting an alteration in 1,3-glucan synthase and/or cell wall structure mediated by the presence of dityrosine. Phenotypically, the wild-type and mutant strains were morphologically similar when cultured in rich yeast extract-peptone-dextrose medium. However in minimal medium, the
cyp56
Δ mutant strain exhibited hyphal growth, in contrast to the wild-type strain, which grew solely in the yeast form. Furthermore,
CYP56
was essential for chlamydospore formation.
Antimicrobial Resistance of Old and Recent
Staphylococcus aureus
Isolates from Poultry: First Detection of Livestock-Associated Methicillin-Resistant Strain ST398
Authors: Nemati Mostafa , Hermans Katleen , Lipinska Urszula , Denis Olivier , Deplano Ariane , Struelens Marc , Devriese Luc A. , Pasmans Frank , Haesebrouck Freddy
Published: July 2008

The susceptibilities of 12 antimicrobial agents for two collections of
Staphylococcus aureus
, isolated in the 1970s and in 2006 from poultry, were determined. For eight antibiotics, the percentage of resistance was significantly higher in the recent isolates. Ten recent isolates were methicillin resistant and had
spa
types t011 and t567, belonging to multilocus sequence type 398. This is the first report of “livestock-associated” methicillin resistant
S. aureus
from healthy poultry.
Pseudomonas aeruginosa
Induces Localized Immunosuppression during Pneumonia
Authors: Diaz Maureen H. , Shaver Ciara M. , King John D. , Musunuri Srinidhi , Kazzaz Jeffrey A. , Hauser Alan R.
Published: July 2008

Hospital-acquired bacterial pneumonia is a common and serious complication of modern medical care. Many aspects of such infections remain unclear, including the mechanisms by which invading pathogens resist clearance by the innate immune response and the tendency of the infections to be polymicrobial. Here, we used a mouse model of infection to show that
Pseudomonas aeruginosa
, a leading cause of hospital-acquired pneumonia, interferes with the ability of recruited phagocytic cells to eradicate bacteria from the lung. Early in infection, phagocytic cells, predominantly neutrophils, are recruited to the lungs but are incapacitated when they enter the airways by the
P. aeruginosa
toxin ExoU. The resulting paucity of functioning phagocytes allows
P. aeruginosa
to persist within the lungs and results in local immunosuppression that facilitates superinfection with less-pathogenic bacteria. Together, our results provide explanations for previous reports linking ExoU-secreting
P. aeruginosa
with more severe pulmonary infections and for the tendency of hospital-acquired pneumonia to be polymicrobial.
Use of
mchI
Encoding Immunity to the Antimicrobial Peptide Microcin H47 as a Plasmid Selection Marker in Attenuated Bacterial Live Vectors
Authors: Fang Chee-Mun , Wang Jin Yuan , Chinchilla Magaly , Levine Myron M. , Blackwelder William C. , Galen James E.
Published: July 2008

Live attenuated bacterial strains expressing heterologous antigens represent an attractive vaccine development strategy. However, the use of drug resistance genes for the selection of expression plasmids introduced into live vectors poses theoretical health risks. Therefore, we developed a novel approach for plasmid selection based on immunity to the antimicrobial peptide microcin H47 (MccH47). Two expression plasmids encoding the reporter green fluorescent protein (GFPuv) were constructed; selection markers comprised either
mchI
, conferring immunity to MccH47 (pGEN222I), or
bla
(encoding β-lactamase), conferring conventional resistance to ampicillin (pGEN222). GFPuv-specific serum immunoglobulin G (IgG) antibody responses were analyzed in mice immunized intranasally either with
Salmonella enterica
serovar Typhi CVD 908-
htrA
or
Shigella flexneri
2a CVD 1208S live vector and were boosted parenterally with purified GFPuv. Similar IgG antibody responses were observed for both pGEN222 and pGEN222I when either CVD 1208S or CVD 908-
htrA
(pGEN222I) was used as the carrier. Interestingly, CVD 908-
htrA
(pGEN222I) elicited a significantly higher IgG response than CVD 908-
htrA
(pGEN222). We also compared the priming potential of homologous priming either with CVD 908-
htrA
(pGEN222I) or CVD 1208S(pGEN222I) to heterologous priming first with CVD 908-
htrA
(pGEN222I) and then with CVD 1208S(pGEN222I) and vice versa. Immunization with two unrelated live vectors significantly enhanced the IgG responses compared to responses engendered by homologous CVD 908-
htrA
(pGEN222I) but not to those of CVD 1208S(pGEN222I). MccH47 offers an alternate system for plasmid selection in bacterial live vectors that greatly improves their clinical acceptability. Furthermore, the success of the heterologous priming strategy supports the feasibility of the future development of multivalent live vector-based immunization strategies against multiple human pathogens.
Mycoplasma pneumoniae
Infection Induces Reactive Oxygen Species and DNA Damage in A549 Human Lung Carcinoma Cells
Authors: Sun Gongping , Xu Xuefeng , Wang Yingshuo , Shen Xiaoyun , Chen Zhimin , Yang Jun
Published: July 2008

Mycoplasma pneumoniae
is a frequent cause of community-acquired bacterial respiratory infections in children and adults. In the present study, using a proteomic approach, we studied the effects of
M. pneumoniae
infection on the protein expression profile of A549 human lung carcinoma cells.
M. pneumoniae
infection induced changes in the expression of cellular proteins, in particular a group of proteins involved in the oxidative stress response, such as glucose-6-phosphate 1-dehydrogenase, NADH dehydrogenase (ubiquinone) Fe-S protein 2, and ubiquinol-cytochrome
c
reductase complex core protein I mitochondrial precursor. The oxidative status of
M. pneumoniae
-infected cells was evaluated, and the results revealed that
M. pneumoniae
infection indeed caused generation of reactive oxygen species (ROS). It was further shown that
M. pneumoniae
infection also induced DNA double-strand breaks, as demonstrated by the formation of γH2AX foci. On the other hand, an ROS scavenger,
N
-acetylcysteine, could inhibit the ROS generation, as well as decrease γH2AX focus formation. This is the first report showing that
M. pneumoniae
infection can directly induce DNA damage, at least partially, through the generation of ROS, and thus this report strengthens the powerful application of proteomics in the study of the pathogenesis of
M. pneumoniae
.
Differential Expression of a Putative CarD-Like Transcriptional Regulator, LtpA, in
Borrelia burgdorferi
Authors: Yang X. Frank , Goldberg Martin S. , He Ming , Xu Haijun , Blevins Jon S. , Norgard Michael V.
Published: July 2008

The availability of microbial genome information has provided a fruitful opportunity for studying regulatory networks in a variety of pathogenic bacteria. In an initial effort to elucidate regulatory networks potentially involved in differential gene expression by the Lyme disease pathogen
Borrelia burgdorferi
, we have been investigating the functions and regulation of putative transcriptional regulatory factors predicted to be encoded within the
B. burgdorferi
genome. Herein we report the regulation of one of the predicted transcriptional regulators, LtpA (BB0355), which is homologous to the transcriptional regulator CarD from
Myxococcus xanthus
. LtpA expression was assessed in response to various environmental stimuli. Immunoblot and quantitative reverse transcription-PCR analyses revealed that unlike many well-characterized differentially regulated
Borrelia
genes whose expression is induced by elevated temperature, the expression of LtpA was significantly downregulated when spirochetes were grown at an elevated temperature (37°C), as well as when the bacteria were cultivated in a mammalian host-adapted environment. In contrast, LtpA was induced at a lower culture temperature (23°C). Further analyses indicated that the downregulation of LtpA was not dependent on the Rrp2-RpoN-RpoS regulatory pathway, which is involved in the downregulation of OspA when
B. burgdorferi
is grown in a mammalian host-adapted environment. LtpA protein levels in
B. burgdorferi
were unaltered in response to changes in the pH in the borrelial cultures. Multiple attempts to generate an LtpA-deficient mutant were unsuccessful, which has hampered the elucidation of its role in pathogenesis. Given that LtpA is exclusively expressed during borrelial cultivation at a lower temperature, a parameter that has been widely used as a surrogate condition to mimic
B. burgdorferi
in unfed (flat) ticks, and because LtpA is homologous to a known transcriptional regulator, we postulate that LtpA functions as a regulator modulating the expression of genes important to
B. burgdorferi
's survival within its arthropod vector.
Immunoproteomics To Examine Cystic Fibrosis Host Interactions with Extracellular
Pseudomonas aeruginosa
Proteins
Authors: Upritchard Hamish G. , Cordwell Stuart J. , Lamont Iain L.
Published: July 2008

The lungs of patients with cystic fibrosis (CF) are typically chronically infected with
Pseudomonas aeruginosa
. We used an immunoproteomics approach to analyze the responses of patients to secreted
P. aeruginosa
proteins. Extracellular proteins from
P. aeruginosa
strain PAO1 that had been grown to stationary phase were separated by two-dimensional polyacrylamide gel electrophoresis and analyzed by Western blotting using sera from four chronically infected patients. Sera from all four patients detected multiple extracellular proteins. The identities of selected proteins recognized by antisera were determined. Production of at least four of these proteins (azurin and three proteases: elastase, PrpL, and PasP) is governed by quorum sensing, consistent with active bacterial quorum sensing in the lungs of CF patients. The CF lung is generally thought to be an iron-deficient environment for infecting bacteria, and growing the bacteria in the presence of an iron-chelating agent, ethylene-diamine-di(
o
-hydroxyphenylacetic acid), enabled detection of additional proteins that were recognized by patient sera. The sera also detected multiple proteins from cells in the logarithmic growth phase, and protein identification suggested that most of these were the result of cell lysis or secretion in membrane vesicles. Comparison with extracellular proteins from a second
P. aeruginosa
strain, strain Pa4, showed that many proteins recognized by patient sera are common to both strains, although there are also some strain-specific extracellular proteins. Our data show that while there are some differences in the responses of different patients to
P. aeruginosa
, there are also many similarities, and that an immunoproteomics approach enables the identification of proteins that are made by
P. aeruginosa
during infection.
Clinical predictors of time to return to competition and of recurrence following hamstring strain in elite Australian footballers
Authors: Warren Price , Gabbe Belinda J , Schneider-Kolsky Michal , Bennell Kim L
Published: July 2008

Objective

To investigate early clinical predictors of time to return to competition and of recurrence following hamstring strain.

Design

Prospective observational study.

Setting

Elite level of Australian football competition.

Participant

59 players who suffered a hamstring strain in 2002 season.

Predictors

Clinical assessment by a physiotherapist and questionnaire.

Main outcome measures

Time taken to return to play and recurrence of hamstring injury within 3 weeks.

Results

Players taking more than 1 day to walk pain-free were significantly more likely (p=0.018) to take longer than 3 weeks to return to competition (adjusted odds ratio 4.0; 95% CI 1.3 to 12.6). Nine players (15.2%) experienced an injury recurrence, all involving the biceps femoris. Recurrence was more likely in players who reported a hamstring injury in the past 12 months (adjusted odds ratio 19.6; 95% CI 1.5 to 261.0; p=0.025).

Conclusion

Time to walk pain-free and previous hamstring injury are predictors of time to return to competition and recurrence, respectively, and should be included in a clinical assessment to aid in prognosis.
Unique among unique. Is it genetically determined?: Table 1
Authors: Gonzalez-Freire M , Santiago C , Verde Z , Lao J I , OIivan J , Gómez-Gallego F , Lucia A
Published: July 2008

The cross-country world championship is one of the best models to study characteristics needed to achieve top-level endurance athletic capacity. We report the genotype combination of a recent cross-country champion (12 km race) in polymorphisms of seven genes that are candidates to influence endurance phenotype traits (ACTN3, ACE, PPARGC1A, AMPD1, CKMM, GDF8(myostatin) andHFE). His data were compared with those of eight other runners (world-class but not world champions). The only athlete with the genotype theoretically more suited to attaining world-class endurance running performance was the case study subject. A favourable genetic endowment, together with exceptional environmental factors (years of altitude living and training in this case), seems to be necessary to attain the highest possible level of running endurance performance.
Temporal Changes in the Reproductive Potential of Female Harp Seals (Pagophilus groenlandicus)
Authors: Bowen W. Don , Capstick Charles K. , Sergeant David E.
Published: July 2008

The Northwest Atlantic harp seal (Pagophilus groenlandicus) population declined by more than 50% between 1952 and the early 1970s. Biological sampling of female reproductive tracts began in 1951 and has continued to the present. We reexamined the extent to which mean age of maturity and fertility rate have changed as population size declined. Mean age of maturity declined from ~ 6.2 yr in 1952 to 4.5 yr in 1979. During this same period fertility rate increased from 85 to 94%. Both parameters have changed concurrently with a decline in numbers. Although it is likely that density-dependent mechanisms are involved, empirical data are lacking.Key words: harp seals, Pagophilus groenlandicus; maturity, fertility, density-dependence
Evidence of Salmo salar × Salmo trutta Hybridization in a North American River
Authors: Beland Kenneth F. , Roberts Franklin L. , Saunders Richard L.
Published: July 2008

Electrophoretic examination of 56 wild Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) from the Stewiacke River, Nova Scotia, revealed one individual believed to be a hybrid between these two species. The possibility of loss of the genetic integrity of each species is considered. A long history of sympatry between Atlantic salmon and brown trout in Europe may have prevented the formation of hybrid swarms as occurred in western North America following introduction of nonindigenous Salmo.Key words: electrophoresis, introgression, enzymes, genetic interaction
A Management Oriented Model of an Abalone Fishery Whose Substocks are Subject to Pulse Fishing
Authors: Sluczanowski Philip R.
Published: July 2008

I present a model of the exploitation of a fishery whose substocks are subject to periodic fishing during which most fish over the legal minimum length IR are removed. Managers should find the model useful because the period P between successive fishing visits to each substock is an index to exploitation rate, which is usually more easily measured and controlled than the fishing mortality F. Each management choice of IR and closure period P affects both long-term biomass yield and egg production. Using a portion of the South Australian abalone (Haliotis sp.) fishery as a case study, I conclude that increases in either control variable can be used to increase significantly egg production while causing only a marginal decrease in yield. Longer closures also offer potential economic benefits. Depending on alternative hypotheses regarding the recruitment process, controls presently in use may threaten survival of the stock by reducing fertile egg production to critical levels.
Bioavailability of Pb and Zn from Mine Tailings as Indicated by Erythrocyte δ-Aminolevulinic Acid Dehydratase (ALA-D) Activity in Suckers (Pisces: Catostomidae)
Authors: Schmitt Christopher J. , Dwyer F. James , Finger Susan E.
Published: July 2008

The activity of the erythrocyte enzyme δ-aminolevulinic acid dehydratase (ALA-D) was measured in 35 catostomids (black redhorse, Moxostoma duquesnei; golden redhorse, M. erythrurum; northern hogsucker, Hypentelium nigricans) collected from three sites on a stream contaminated with Pb-, Cd-, and Zn-rich mine tailings and from an uncontaminated site upstream. Enzyme activity was expressed in terms of hemoglobin (Hb), DNA, and protein concentrations; these variables can be determined in the laboratory on once-frozen blood samples. Concentrations of Pb and Zn in blood and of Pb in edible tissues were significantly higher, and ALA-D activity was significantly lower, at all three contaminated sites than upstream. At the most contaminated site, ALA-D activity was 62–67% lower than upstream. Lead concentrations in the edible tissues and in blood were positively correlated (r = 0.80), whereas ALA-D activity was negatively correlated with Pb in blood (r = −0.70) and in edible tissues (r = −0.59). Five statistically significant relations between Pb and Zn in blood and ALA-D activity were determined. The two models that explained the highest percentage (> 74%) of the total variance also included factors related to Hb concentration. All five significant models included negative coefficients for variables that represented Pb in blood and positive coefficients for Zn in blood. The ALA-D assay with results standardized to Hb concentration represents an expedient alternative to the more traditional hematocrit standardization, and the measurement of ALA-D activity by this method can be used to document exposure of fish to environmental Pb.
Logging Impacts and Some Mechanisms that Determine the Size of Spring and Summer Populations of Coho Salmon Fry (Oncorhynchus kisutch) in Carnation Creek, British Columbia
Authors: Scrivener J. C. , Andersen B. C.
Published: July 2008

Natural patterns in emergence times, seaward movements, instream distributions, densities, and growth of coho salmon fry (Oncorhynchus kisutch) between March and September are contrasted with patterns observed during and after logging in the Carnation Creek watershed. After streamside logging in 1976–77, fry emerged up to 6 wk earlier and moved seaward more quickly than during years before logging. These observations are attributed to higher water temperatures during the winter and to emergence during a period of more frequent freshets. Increased fry movement from the stream could result in habitat being underutilized. In sections affected by intense streamside logging, the deposition of "fine" logging debris led to increased fry densities during the summers of 1977 and 1978. After major freshets in November 1978, which removed this fine debris and affected channel morphology in these sections, fry densities declined below those observed prior to logging. Growth rate of fry was inversely correlated with density in all stream sections. Growth rates, after correction for density, tended to be greater in all sections after the adjacent streamside was logged. Larger fry and more variable numbers of fry remained in the stream in September after logging than before logging. Their increased size is attributed to the longer growing season afforded by earlier emergence. This complex of interacting factors determines the number and size of fry in autumn and it can influence the production of smolts the following spring.
Investment Decision Making by Fishermen
Authors: Lane Daniel E.
Published: July 2008

Individual fishermen make investment decisions in an environment which is competitive and highly variable from season to season. Extensive variability means that economic survival must be a primary consideration in the investment decision process. In this paper, fishermen's investment decisions are modelled as a probabilistic dynamic programming problem in discrete time. Fishermen are assumed to make rational decisions based on income expectations and subject to survivability conditions to maximize the net worth of the fishing enterprise at the end of a finite planning horizon. The formal analysis of the investment model is presented and the model is applied to trailer fishermen of the British Columbia commercial fishing fleet. The results present an accurate picture of actual investment decisions and provide valuable insights into the behavioral basis of investment decision making by fishermen. Understanding the investment decisions of fishermen has implications for planning and regulation in fisheries: insights gained into the key factors provide the basis for the development of strategic long-term policies that anticipate fishermen's behavior. The consequences will be a movement away from reactive, short-term policies which have characterized fisheries regulation to date.
Effects of Reproduction upon Molting and Growth in Female American Lobsters (Homarus americanus)
Authors: Nelson K. , Hedgecock D. , Borgeson W.
Published: July 2008

American lobster (Homarus americanus) females characteristically extrude eggs (E) in the summer of the year following a summer or autumn molt (M), but young females may extrude in the same year. The subsequent M is delayed until after hatching, resulting in the former case in a 2-yr reproductive molt cycle, measuring from M to M. Adult female lobsters were exposed to periods of short days (8 h light: 16 h dark) followed by long day onset (L) (16 h light: 8 h dark) at different times with respect to M, or as controls were kept under continuous long-day conditions. In this way were generated molt cycles with delayed or undelayed extrusions, as well as ones with incomplete vitellogeneses resulting from too-long delayed L, and molt cycles in which vitrellogenesis did not begin (control group). Delayed L results in delayed E and M, as measured either in days or in day-degrees above 6 °C. An incompleted vitellogenesis following a too-long delayed L changes neither the duration of the molt cycle nor its characteristic positive correlation with female size; the duration of molt cycles containing either delayed or undelayed E appears in contrast to become independent of size. Intermolt intervals following prior E are shorter than those following anovulatory cycles. Retention of the clutch to hatching is associated with an additional increment to the intermolt interval. The results suggest that following E, a "reproductive" program replaces the "somatic" program of control of molt cycle duration. Incompleted vitellogeneses are associated with significantly smaller molt increments and growth rates than in the evidently avitellogenic continuous long-day control group, even though intermolt duration and its relation to size remain the same. Growth rates of molt cycles containing incompleted vitellogeneses are significantly higher than ones containing E only if that is delayed. Differential dependence of molt cycle duration and growth rate measures upon size and temperature indicate that molting and growth are distinct and rather independently controlled processes in adult lobsters, however tightly linked they may be in juveniles. Implications for molting and reproduction in the natural environment are discussed.
Comparative Physiological Ecology of Centrarchids in Hyposaline Environments
Authors: Peterson Mark S.
Published: July 2008

Empirical evidence and data from this study suggests that there are intrafamilial differences in salinity tolerance that apparently change longitudinally along salinity gradients. Lepomis punctatus and Micropterus punctulatus require a significantly longer time to acclimate to increased salinity than L. microlophus, which apparently acclimates within 1 h. Both increased salinity (0–8 ppt) and the time (1–72 h) exposed to a particular salinity impact osmotic and hematocrit regulation. Observed intrafamilial differences in osmotic and hematocrit regulation underlay the distribution and relative abundance of centrarchids and could explain their seasonal use o low salinity marshes. Furthermore, the > 12-h acclimation times of L. punctatus and M. punctulatus suggest that these two species may never become fully acclimated to a salinity during a diurnal tidal cycle.
Timing of Spawning in Norwegian Atlantic Salmon (Salmo salar)
Authors: Heggberget Tor G.
Published: July 2008

A hypothesis that thermal regime regulates the timing of spawning in Atlantic salmon (Salmo salar) was analysed by correlating time of commencement and peak of spawning in 16 Norwegian streams with temperature, latitude, and stream flow. Only temperature during incubation of the eggs proved to have any statistically significant effect. Since the duration of egg incubation is known to depend on temperature regime (i.e. on degree-days), a similar linking of spawning time to stream temperature allows spawning to occur at a time which will result in hatching of eggs at a specific and presumably optimal time for survival of fry.
Wind-Aided Recruitment of Canadian Arctic Cisco (Coregonus autumnalis) into Alaskan Waters
Authors: Fechhelm Robert G. , Fissel David B.
Published: July 2008

Summer wind data collected at Barter Island, Alaska, were compared with commercial fishery catches of arctic cisco (Coregonus autumnalis) at the Colville River, Alaska, for the period 1967–85. There was a significant (p = 0.036) association between yearly catch-per-unit-effort and the percent of easterly winds after adjusting for a 5-yr differential in the two time series. Results suggest that young-of-the-year fish which spawn in Canada's Mackenzie River are aided in their westward dispersal into Alaskan waters via wind-driven longshore currents. The greater the prevalence of easterly winds (westerly currents), the greater the recruitment. Increased recruitment manifests itself as an increase in Alaskan commercial fishery catch some 5-yr later when fish have grown to a size that renders them susceptible to commercial nets.
Contrasting Patterns of Net- and Nanoplankton Production and Biomass among Lakes
Authors: Watson Susan , McCauley Edward
Published: July 2008

The relative contribution of nanoplankton to total algal biomass was shown to be negatively correlated with total phosphorus during summer over a wide range of lakes. We hypothesize that this pattern can be explained either by changes in the relative growth rates of net- or nanoplankton with increased nutrient levels, or through the regulation of the nanoplankton biomass by herbivores, allowing disproportionate increases in netplankton biomass in more eutrophic systems. These explanations were tested by examining the relationships between net primary production (grams of carbon per cubic metre per year) and biomass (micrograms per litre) of these size fractions and total phosphorus concentrations (micrograms per litre) using literature data from lakes through-out the world. The production of the net- and nanoplankton vary similarly with total phosphorus, while the biomasses (and thus the ratios of production to biomass) of the two groups show significantly different relationships. Our results support the hypothesis that changes in the size distribution of summer phytoplankton with enrichment seem to be influenced more by herbivores than by changes in the relative growth rates of the two size fractions.
Potential Fishery for Lake Sturgeon (Acipenser fulvescens) as Indicated by the Returns of the Hudson's Bay Company Lac la Pluie District
Authors: Holzkamm Tim , McCarthy Michael
Published: July 2008

The isinglass returns for the Hudson's Bay Company Lac la Pluie District have been used to estimate the Ojibway harvest of lake sturgeon (Acipenser fulvescens) from 1823 to 1885. The majority of these fish were taken in the Rainy River from spawning runs originating in Lake of the Woods. American commercial fishing of sturgeon in Lake of the Woods began in 1888, with commercial operations on the Canadian side following within a few years. Initially high production levels characterize the non-Ojibway fishery for the first 20 yr, with rapid declines due to depleted sturgeon populations in the following years. Similar responses to commercial sturgeon fishing in other areas have led many to conclude that fisheries stocks could not support a significant sustained commercial fishery. In contrast, the Ojibway harvest during 63 yr of fur trade records indicates potential for a substantial sustained commercial sturgeon harvest from the Lake of the Woods basin. The same conclusion is not evident from American and Canadian records of sturgeon harvests from the same drainage basin.
Statistical Power Analysis can Improve Fisheries Research and Management
Authors: Peterman Randall M.
Published: July 2008

Ninety-eight percent of recently surveyed papers in fisheries and aquatic sciences that did not reject some null hypothesis (H0) failed to report β, the probability of making a type II error (not rejecting H0when it should have been), or statistical power (1 – β). However, 52% of those papers drew conclusions as if H0were true. A false H0could have been missed because of a low-power experiment, caused by small sample size or large sampling variability. Costs of type II errors can be large (for example, for cases that fail to detect harmful effects of some industrial effluent or a significant effect of fishing on stock depletion). Past statistical power analyses show that abundance estimation techniques usually have high β and that only large effects are detectable. I review relationships among β, power, detectable effect size, sample size, and sampling variability. I show how statistical power analysis can help interpret past results and improve designs of future experiments, impact assessments, and management regulations. I make recommendations for researchers and decision makers, including routine application of power analysis, more cautious management, and reversal of the burden of proof to put it on industry, not management agencies.
Zooplankton Species Associations in Quebec Lakes: Variation with Abiotic Factors, Including Natural and Anthropogenic Acidification
Authors: Pinel-Alloul Bernadette , Méthot Ginette , Verreault Ghislain , Vigneault Yvan
Published: July 2008

Abundances and biomass of 38 zooplankton species and accompanying abiotic data from 54 Quebec lakes were subjected to cluster and correlation analysis to determine (1) characteristic zooplankton associations of cooccurring species, (2) relative importance of abiotic variables in lake typology, and (3) relationships between the integrated environmental factors derived from lake morphometry, water quality, and acidification level, and the structure of zooplankton communities. The eight groups of species identified in the cluster analysis may be considered separate "species associations" characterized by distinct patterns of distribution in Quebec lakes. Differences in mean pH and sulphate concentrations can be detected between groups of lakes representing the different species associations. Factor analysis produced seven factor scores which explain 82% of the total variance of the morphological, physical, and chemical variables. The distribution pattern of acidity or alkalinity represents the major feature in water chemistry variation, but lake morphology also account for the observed environmental variability. Each factor represents an integrated environmental property correlated with a set of colinear abiotic variables. These factors are correlated with zooplankton species abundances and biomass. The community structure, whether expressed in size classes or in trophic groups, tends to vary among sets of lakes of different pH.