bluuebunny/crossref_metadata_2025 huggingface dataset:
Childhood stroke in Eastern Province, KSA: pattern, risk factors, diagnosis and outcome
Authors: Emam Abdelhady Taha , Ali Alsayed Mohammed , Babikr Malek Ahmed
Published: July 2009

Background and purpose:  Stroke has been increasingly recognized in children in recent years, but diagnosis and management can be difficult because of the diversity of underlying risk factors, atypical presentation and the absence of a uniform treatment approach. The aim of this study was to examine risk factors, clinical presentation, imaging findings and outcomes of paediatric stroke in Eastern Province, Kingdom of Saudi Arabia (KSA).

Subjects and methods:  We evaluated 25 patients (11 boys and 14 girls) using computerized tomography scan of the brain, magnetic resonance (MR) imaging and MR angiography. Cardiac assessment, haematological tests, immunological tests, infection and metabolic screening were also performed in the patients. After discharge, the patients were monitored regularly in the neurology clinic to detect their outcomes.

Results:  A total of 76% of the patients presented with ischaemic stroke, while the remaining 24% had haemorrhagic stroke. Sickle cell disease (SCD) was the commonest risk factor for stroke (36%) followed by non determinate causes (20%). Seizure was the commonest clinical presentation (54%) followed by haemiplegia (31%) and decreased level of consciousness (30%). Recurrence occurred in SCD patients (80%) and patients with moyamoya disease (20%). Regarding the outcome, long‐term deficit was the commonest (44%), while short‐term deficit and death were equal (28% each).

Conclusion:  Our study in Eastern Province, KSA, showed agreement with other studies regarding risk factors, clinical presentation, imaging features and outcomes of stroke in children, yet with some points of differences, which are as follows: (1) SCD is the commonest risk factor in our study population, while in Chinese study it was not, (2) The percentage of cardiac disorders as a risk factor in this study was less than that in the European and American studies, and (3) there was relative discrepancy regarding predictors of outcome.
Editor's Introduction: Special Issue on the Next Big Questions in Psychology
Authors: Diener Ed
Published: July 2009

In this issue of Perspectives on Psychological Science, we learn what 18 leading psychologists believe are the next big research questions in their respective fields. I invited about 20 of our most outstanding scholars to tell us what they believe are the most important questions to be asked in the upcoming decade. Not unexpectedly, the contributions are wide ranging both in content and in the way the authors framed the question of what is important. The range of articles, from psychoneuroimmunology to human—android interactions, clearly indicates the enormous scope of psychology. My hope is that both freshly minted and senior scientists alike might gain from these insights into the research they should pursue in the years ahead.
Psychoneuroimmunology: Psychology's Gateway to the Biomedical Future
Authors: Kiecolt-Glaser Janice K.
Published: July 2009

How do stressful events and negative emotions influence the immune system, and how big are the effects? This broad question has been intensely interesting to psychoneuroimmunology researchers over the last 3 decades. Many promising lines of work underscore the reasons why this question is still so important and pivotal to understanding and other advances. New multidisciplinary permutations provide fresh vistas and emphasize the importance of training psychologists more broadly so that they will be central and essential players in the advancement of biomedical science.
Can We Improve Our Physical Health by Altering Our Social Networks?
Authors: Cohen Sheldon , Janicki-Deverts Denise
Published: July 2009

Persons with more types of social relationships live longer and have less cognitive decline with aging, greater resistance to infectious disease, and better prognoses when facing chronic life-threatening illnesses. We have known about the importance of social integration (engaging in diverse types of relationships) for health and longevity for 30 years. Yet, we still do not know why having a more diverse social network would have a positive influence on our health, and we have yet to design effective interventions that influence key components of the network and in turn physical health. Better understanding of the role of social integration in health will require research on how integrated social networks influence health relevant behaviors, regulate emotions and biological responses, and contribute to our expectations and worldviews.
Perspectives on Preference Aggregation
Authors: Regenwetter Michel
Published: July 2009

For centuries, the mathematical aggregation of preferences by groups, organizations, or society itself has received keen interdisciplinary attention. Extensive theoretical work in economics and political science throughout the second half of the 20th century has highlighted the idea that competing notions of rational social choice intrinsically contradict each other. This has led some researchers to consider coherent democratic decision making to be a mathematical impossibility. Recent empirical work in psychology qualifies that view. This nontechnical review sketches a quantitative research paradigm for the behavioral investigation of mathematical social choice rules on real ballots, experimental choices, or attitudinal survey data. The article poses a series of open questions. Some classical work sometimes makes assumptions about voter preferences that are descriptively invalid. Do such technical assumptions lead the theory astray? How can empirical work inform the formulation of meaningful theoretical primitives? Classical “impossibility results” leverage the fact that certain desirable mathematical properties logically cannot hold in all conceivable electorates. Do these properties nonetheless hold true in empirical distributions of preferences? Will future behavioral analyses continue to contradict the expectations of established theory? Under what conditions do competing consensus methods yield identical outcomes and why do they do so?
Why Do Different Individuals Progress Along Different Life Trajectories?
Authors: Smith Gregory T.
Published: July 2009

The core marker of progress in psychological science is the degree to which our work enhances the welfare of people. In order to effectively enhance human welfare, we must develop comprehensive models that explain why different individuals progress along different life trajectories. Exciting theoretical accounts that describe transitional processes from gene polymorphisms through moment-to-moment behavior are beginning to emerge. These early accounts highlight opportunities to investigate specific transitional steps along that long pathway, the need to understand the universal and the contextual aspects of psychological processes, and the need to define and measure psychological constructs with more precision and clarity. It is likely that creative new research in each of these areas will bring enormous progress over the coming decade.
Achieving and Sustaining a Good Life
Authors: Park Nansook , Peterson Christopher
Published: July 2009

How can we live well? To answer this question, psychology must acknowledge and integrate its descriptive and prescriptive components. One of psychology's strengths has been its willingness to embrace different purposes, perspectives, and approaches, and this recommendation is in the spirit of the field's history. At present, psychology knows more about people's problems and how to solve them than it does about what it means to live well and how to encourage and maintain such a life. Moreover, what is known is often fragmented because of psychology's specialization. Our article calls for further discussion in psychological terms of what it means to live well; the study of actual people and how they behave; multivariate, multimethod, and longitudinal research; more sophisticated interventions; interdisciplinary collaboration; and translational research.
What Kind of Empirical Research Should We Publish, Fund, and Reward?: A Different Perspective
Authors: Rozin Paul
Published: July 2009

When evaluating empirical papers for publication, grant proposals, or individual contributions (e.g., awarding tenure), the basic question one should ask is how much the contribution adds to understanding in psychology and not whether the contribution takes a particular form or represents one particular model of how to do empirical studies. Academic psychology has flourished with its mastery of the hypothesis-experiment model of science and its expertise in generating and eliminating alternative hypotheses and isolating causation. These accomplishments are a critical part of psychology, and they are well and appropriately taught by psychologists. However, they are only a part of science and should not comprise the almost exclusive criteria for evaluating research. In particular, discovery of fundamental phenomena, such as functional relations that apply to the real world and have generality, should have a higher priority in psychology. Such findings have been the basis for theoretical advances in other natural sciences.
Mesopotamian Roots for the Belief in the Resurrection of the Dead
Authors: Studevent‐Hickman Benjamin
Published: July 2009

The belief in the resurrection of the dead, a defining element of the Christian faith, did not begin with Christianity. At the time of the earliest Christians, several factions of Judaism held some form of the belief, disagreeing on whether it was physical or spiritual in nature. For the physical resurrection, evidence already appears in later writings of the Hebrew Bible; as a result, many scholars place the origin of the belief in the post‐exilic period, attributing it to foreign influence, generally from Canaan or Persia. But there is earlier evidence, both in and outside the Hebrew Bible, in those cases where a corpse returns to life, even temporarily. As argued here, it isthisphenomenon, above all, that forms the basis of the belief in the physical resurrection in the Judeo‐Christian tradition, and, whereitis concerned, a stronger cross‐cultural parallel is ancient Mesopotamia. In ancient Mesopotamia, there was clearly a belief that the dead could return from the netherworld to the land of the living, and it was part of a conceptual framework that integrated death, disease, medicine, and healing – as it was in the Hebrew Bible. For the history of religion, this dates the early roots of the belief in the physical resurrection of the dead centuries earlier than scholars have recognized.
The Place of Nature in Twelfth‐Century Spirituality
Authors: Ritchey Sara
Published: July 2009

This essay considers recent scholarship on nature and spirituality in the twelfth century, the period when Europeans ostensibly ‘discovered’ nature. In doing so, it demonstrates the ways in which certain developments in twelfth‐century Christian spirituality can participate in and enlarge the emerging conversation on the material conditions of human spirituality that is presently taking place in religious studies more generally as a result of our current ecological consciousness. Twelfth‐century Christian spiritualities illuminate how people have created a material context through which they can better achieve spiritual experiences. Experiments in twelfth‐century Christianity can help us greatly in thinking about how individuals and communities have crafted a place in the natural world as a technique for enhancing the experience of god's presence.
Over-expression of α-galactosidase in pea seeds to reduce raffinose oligosaccharide contentThis paper is one of a selection of papers published in a Special Issue from the National Research Council of Canada – Plant Biotechnology Institute.
Authors: Polowick Patricia L. , Baliski David S. , Bock Cheryl , Ray Heather , Georges Fawzy
Published: July 2009

The raffinose family of oligosaccharides (RFO) is a series of complex carbohydrates stored in seeds of many plant families, especially in legumes. The digestive system of nonruminant animals, including that of humans, cannot break down all of the chemical bonds in these carbohydrates; therefore, catabolism is achieved anaerobically by intestinal flora. The resulting digestive problems reduce acceptance and limit the widespread consumption of these otherwise nutritious seeds. To demonstrate a solution to this problem, transgenic lines of pea ( Pisum sativum  L.) expressing the α-galactosidase gene from coffee ( Coffea arabica L.) were developed. Plants with a single copy of the inserted gene were selected, and two of these lines showed significant reductions of up to 40% in oligosaccharide content (raffinose, stachyose). Quantitative RT-PCR confirmed the presence of the α-galactosidase RNA in both leaves and cotyledons. Sugars were analyzed using whole seeds or only a portion of a seed; in the latter case, germination rates for each of the seeds analyzed were determined. The reduced raffinose contents did not affect germination rates, which remained very high (96%). The relative oligosaccharide contents of tissues within a seed also were determined; these were highest in the embryo axis, lower in the cotyledon and lowest in the seed coat.
Molecular and functional characterization ofBrassica BREVIPEDICELLUSorthologs involved in inflorescence architectureThis paper is one of a selection of papers published in a Special Issue from the National Research Council of Canada – Plant Biotechnology Institute.
Authors: Dumonceaux Tim , Venglat Sathya Prakash , Kushalappa Kumuda , Selvaraj Gopalan , Datla Raju
Published: July 2009

The diversity of inflorescence architecture in angiosperms relates to attracting pollinators and allowing the effective dispersal of seeds. Molecular understanding of the genetic factors regulating inflorescence architecture from the model system of Arabidopsis could provide critical insights for addressing this developmental process/pathway in a closely related crop species like Brassica napus L. Towards this objective, we have isolated and characterized the orthologs of the homeobox gene BREVIPEDICELLUS (BP) in three Brassica species, B. napus (BnBP), Brassica rapa  L. (BrBP), and Brassica oleracea  L. (BoBP). These Brassica orthologs show a high degree of conservation at the nucleotide and amino acid level, including the homeodomain and the intron positions. The B. napus ortholog complemented the Arabidopsis bp null allele and overexpression of BnBP in B. napus transgenic lines resulted in altered leaf phenotypes. Together, these results suggest that Brassica BP genes are functional orthologs of Arabidopsis BP. Ectopic expression of AS2, a negative regulator of BP encoding a LOB domain transcription factor, in transgenic B. napus produced compact inflorescence architecture reminiscent of the loss-of-function bp mutant phenotype described previously in Arabidopsis. These results provide evidence in support of BP as a potential target gene for modifying inflorescence architecture in Brassica crop species.
Adaptive epigenetic memory of ancestral temperature regime inArabidopsis thalianaThis paper is one of a selection of papers published in a Special Issue from the National Research Council of Canada – Plant Biotechnology Institute.
Authors: Whittle C. A. , Otto S. P. , Johnston M. O. , Krochko J. E.
Published: July 2009

Although certain acquired nongenetic (i.e., epigenetic) traits are known to be heritable in plants, little is known currently about whether environmental parameters can induce adaptive epigenetic responses in plants and whether such effects can persist through generations. We used an experimental design based on classical genetics principles to assess whether plants respond to the environmental conditions of their ancestors in an adaptive epigenetic manner. An extensive examination of genetically identical Arabidopsis thaliana (L.) Heynh lines exposed to mild heat (30 °C) or cold (16 °C) treatments in the parental and F1generations revealed that the prior elevated temperature regime lead to a greater than fivefold improvement in fitness (seed production per individual) for plants exposed to heat in a later generation (F3). The heat-specific fitness improvements among F3plants were observed even though the heat-treated parental and F1generations were followed by a generation grown at a normal temperature (F2) and point towards a temperature-induced adaptive epigenetic phenomenon. No such adaptive responses were detected for cold-treated plants, indicating that there are distinctive biological processes inherent to these two temperature regimes. Overall, the data are consistent with the existence of an environmentally induced epigenetic and heritable adaptive response in plants.
Molecular cloning of an aldehyde dehydrogenase implicated in artemisinin biosynthesis in Artemisia annuaThis paper is one of a selection of papers published in a Special Issue from the National Research Council of Canada – Plant Biotechnology Institute.
Authors: Teoh Keat H. , Polichuk Devin R. , Reed Darwin W. , Covello Patrick S.
Published: July 2009

Limitations in the supply of the antimalarial compound artemisinin from Artemisia annua  L. have led to an interest in understanding its biosynthesis and enhancing its production. Recent biochemical and molecular genetic data have implicated dihydroartemisinic aldehyde as a precursor to the corresponding acid, which is then converted to artemisinin. Thus, it is important to understand the enzyme or enzymes involved in dihydroartemisinic aldehyde oxidation. Given its activity on artemisinic aldehyde, the cytochrome P450 CYP71AV1 was investigated for its ability to oxidize dihydroartemisinic aldehyde. However, no net activity was detected. In a search for alternative enzymes that could catalyze the oxidation, an expressed sequence tag (EST) collection from A. annua was investigated for relevant cDNAs. This led to the isolation of a full-length cDNA encoding an aldehyde dehydrogenase homologue, named Aldh1, which is highly expressed in trichomes. Expression of the cDNA in E. coli and characterization of the purified recombinant enzyme revealed that the gene product catalyses the NAD(P)-dependent oxidation of the putative artemisinin precursors, artemisinic and dihydroartemsinic aldehydes, and a limited range of other aldehydes. The observed enzyme activity of Aldh1 and the expression pattern of the corresponding gene suggest a role in artemisinin biosynthesis in the glandular secretory trichomes of A. annua.
Molecular cloning and characterization of Dbr1, a 2-alkenal reductase from Artemisia annuaThe nucleotide sequence reported in this article has been deposited in the GenBank database under accession No. FJ750460.This paper is one of a selection of papers published in a Special Issue from the National Research Council of Canada – Plant Biotechnology Institute.
Authors: Zhang Yansheng , Teoh Keat H. , Reed Darwin W. , Covello Patrick S.
Published: July 2009

The molecular genetics of carbon–carbon double bond reduction in the plant Artemisia annua  L. was studied. Expressed sequence tags from this plant were investigated for sequences with similarity to known double-bond reductases. This resulted in the isolation of a cDNA, corresponding to the gene A. annua Dbr1 (Double bond reductase1), encoding a member of the medium chain dehydrogenase/reductase protein superfamily with sequence similarity to tobacco allyl alcohol dehydrogenase. Recombinant A. annua Dbr1 protein was purified from Escherischia coli and shown to catalyze the reduction of the carbon–carbon double bond of 2-alkenals. This activity included the reduction of the double bond at C11–C13 in the artemisinin precursor artemisinic aldehyde, albeit with unnatural stereochemistry. The substrate specificity, product stereochemistry, and expression pattern of A. annua Dbr1 point to its involvement in planta in the detoxification of 2-alkenals, which may be generated under oxidative stress conditions.
Proanthocyanidin biosynthesis in the seed coat of yellow-seeded, canola qualityBrassica napusYN01-429 is constrained at the committed step catalyzed by dihydroflavonol 4-reductaseThis paper is one of a selection of papers published in a Special Issue from the National Research Council of Canada – Plant Biotechnology Institute.
Authors: Akhov Leonid , Ashe Paula , Tan Yifang , Datla Raju , Selvaraj Gopalan
Published: July 2009

The yellow seed characteristic in Brassica napus  L. is desirable because of its association with higher oil content and better quality of oil-extracted meal. YN01-429 is a yellow-seeded canola-quality germplasm developed in Canada arising from several years of research. Seed-coat pigmentation is due to oxidized proanthocyanidins (PA; condensed tannins) derived from phenylpropanoids and malonyl CoA. We found PA accumulation to be most robust in young seed coats (20 d post anthesis; dpa) of a related black-seeded line N89-53 and only very little PA in YN01-429, which also contained much less extractable phenolics. The flavonol content, however, did not show as great a difference between these two lines. Furthermore, sinapine, a product of the general phenylpropanoid metabolism, was present at comparable levels in the embryos of both lines. Dihydroflavonol reductase (DFR) activity that commits phenolics to PA synthesis was lower in YN01-429 seed coats. The results of Southern blot and in silico analyses were indicative of two copies of the DFR gene in B. napus. Both copies were functional in YN01-429, ruling out homeoallelic repression or silencing, but together they showed very low expression levels (17-fold fewer transcripts) relative to DFR activity in N89-53 seed coats. These results collectively suggest that YN01-429 differs in regulatory circuits that impact the PA synthesis branch much more than the flavonol synthesis branch in the seed coats and such circuits do not impinge upon general phenylpropanoid metabolism in the embryos.
Paleomagnetic dating of the northern Alberta kimberlites
Authors: Kravchinsky Vadim A. , Eccles D. Roy , Zhang Rui , Cannon Matthew
Published: July 2009

Due to the vast amount of economic interest diamonds have created in northern Alberta, there is a need to produce an accurate geological model for the northern Alberta kimberlite province. To aid in the development of such a model, the emplacement ages of two kimberlite occurrences, K5 and K6 from the Buffalo Head Hills region of north-central Alberta, and the ultramafic Mountain Lake body from northwestern Alberta were estimated using paleomagnetic methods. Paleomagnetic poles obtained in our study do not differ statistically from the reference poles for late Mesozoic – Cenozoic for North America ( Besse and Courtillot 2002 ). With the aid of polarity determinations, palynology, and radiogenic dating, the paleomagnetic results allow for new constraints on the emplacement age of the selected ultramafic occurrences. The paleomagnetic emplacement ages established for the K5, K6, and Mountain Lake bodies are 90–83 Ma, 83.0–79.1 Ma, and not older than 79.1 Ma, respectively.
Oxygen deficiency impacts on burying habitats for lesser sandeel, Ammodytes tobianus, in the inner Danish waters
Authors: Behrens Jane W. , Ærtebjerg Gunni , Petersen Jens Kjerulf , Carstensen Jacob
Published: July 2009

Starting in 1980s, the inner Danish waters have yearly been exposed to seasonal oxygen deficiency (hypoxia). Through spatial–temporal interpolation of monitoring data (1998–2005), we investigated oxygen deficiency impacts on suitable burying habitats for lesser sandeel ( Ammodytes tobianus ). Furthermore, the consequences of a predicted 4 °C temperature increase within this century were investigated. Maps of bottom oxygen deficiency (oxygen saturation ≤ Scrit of sandeel) were overlaid on maps of sediment composition. Throughout the study period (1998–2005), about 8% of the suitable sediments were affected by oxygen deficiency during an average year and 23% in the most severe year. Regional differences underlay the interannual variations. The extent of oxygen deficiency in enclosed regions varied from 20% to 33% of the suitable seabed being affected, whereas in open-water regions oxygen deficiency problems were limited during average years. However, large areas of the open-water seabed experienced oxygen deficiency during severe years. In such years, under a 4.0 °C temperature increase scenario, the extent of oxygen deficiency on open-water suitable patches was predicted to increase from 25% to about 40%.
Atlantic cod (Gadus morhua) distribution response to environmental variability in the northern Gulf of St. Lawrence
Authors: Ruppert Jonathan L.W. , Fortin Marie-Josée , Rose George A. , Devillers Rodolphe
Published: July 2009

Atlantic cod ( Gadus morhua ) distribution patterns and the behavioral (site fidelity), biotic (prey and predators), and environmental factors that determine them are fundamental to cod’s historic importance as a commercial species in the North Atlantic. Using classification and regression tree analysis (CART), we compared two periods (1991–1995 and 1998–2004) with contrasting bottom temperature and salinity regimes to determine regional factors that best explained cod distribution and catch weight per tow from summer surveys in the northern Gulf of St. Lawrence (the feeding period of cod). The classification tree analysis indicated that the presence or absence of cod was chiefly determined by depth in both of these periods. In contrast, the regression tree analysis determined that cod catch weight distributions were explained by different variables in each period. In the colder period (1991–1995), the distribution of catch weights was explained well by environmental variables (bottom temperature, salinity, depth); however, in the warmer period (1998–2004), distributions were best explained by variables from the previous year. These results indicate that the spatiotemporal dynamics of environmental conditions are likely to influence the loyalty of cod to specific feeding grounds and imply that cod responses to the environment could be susceptible to long-term environmental (e.g., bottom–habitat) and climate change.
Clostridium botulinum type E occurs and grows in the alga Cladophora glomerata
Authors: Byappanahalli Muruleedhara N. , Whitman Richard L.
Published: July 2009

In recent years, massive avian die-offs from Clostridium botulinum type E infection have occurred in the Sleeping Bear Dunes National Lakeshore (SLBE) area of Lake Michigan. These outbreaks have been coincidental with massive blooms of the green algae Cladophora , mostly Cladophora glomerata . We tested the hypothesis that Clostridium botulinum type E can grow under suitable conditions in these algal mats. In a lab mesocosm study, Cladophora from four outbreak-impacted beaches from SLBE were compared with four unimpacted beaches in the Milwaukee–Racine area for bontE gene of Clostridium botulinum. Frequency of the bontE gene was higher after incubation (25 °C for up to 6 weeks) of Cladophora from impacted vs. the unimpacted area. Since no type E gene was detected initially in Cladophora from any of the eight locations, we infer that the increased occurrence of type E gene arose from spore germination or vegetative Clostridium growth within the existing algal mats of SLBE. Moreover, we found that the congener Clostridium perfringens readily grows in mesocosms containing Cladophora.
Bioenrichment of trace elements in a series of ponds near a northern fulmar (Fulmarus glacialis) colony at Cape Vera, Devon Island
Authors: Brimble Samantha K. , Blais Jules M. , Kimpe Linda E. , Mallory Mark L. , Keatley Bronwyn E. , Douglas Marianne S.V. , Smol John P.
Published: July 2009

Seabirds are an important link between their marine feeding areas and their terrestrial breeding environments, transporting both marine-derived nutrients and contaminants and then depositing them on land in their guano. In this study, the impact of a large northern fulmar ( Fulmarus glacialis ) colony on the water chemistry of 26 nearby ponds spanning a gradient of seabird influence was investigated at Cape Vera, Devon Island, in the Canadian High Arctic. The presence of the fulmar colony has led to nutrient and trace element enrichment in the ponds, as evidenced by the close association among As, Cd, Co, Cu, Li, Mn, Mo, Ni, Sb, and Sr and the ornithogenic gradient. The ponds most affected by the fulmar colony were characterized by increased primary production, high organic carbon concentrations, and elevated pH — conditions favorable for the in situ removal of metals from the water column. Despite this, the highest trace element concentrations were observed in the seabird-influenced ponds, suggesting that these elements have undergone biotransport.
The effect of light intensity on the availability of walleye pollock (Theragra chalcogramma) to bottom trawl and acoustic surveys
Authors: Kotwicki Stan , De Robertis Alex , von Szalay Paul , Towler Rick
Published: July 2009

Quantitative assessment of semidemersal fish such as walleye pollock ( Theragra chalcogramma ) is difficult because the proportion of walleye pollock available to standardized surveys varies temporally and spatially. The US National Marine Fisheries Service’s Alaska Fisheries Science Center conducts bottom trawl (BT) surveys to estimate the demersal portion of the walleye pollock population and acoustic trawl (AT) surveys to estimate the pelagic portion. Both surveys are conducted during daylight hours to minimize variability due to diel changes in vertical distribution. To test if daytime near-bottom light intensity affects the proportion of walleye pollock available to the BT survey, we concurrently measured light and walleye pollock abundance on the Bering Sea shelf. Logistic regression models demonstrated that both light and depth affected walleye pollock abundance estimates by either BT or AT surveys, with more walleye pollock available to the BT survey under high illumination and at shallow depths and less walleye pollock available to the AT survey under these conditions. This finding suggests that daytime survey catchability for walleye pollock depends on depth and light intensity and that incorporation of light measurements could improve the precision of abundance estimates of semidemersal species such as walleye pollock.
Influence of diel cycles of respiration, chlorophyll, and photosynthetic parameters on the summer metabolic balance of temperate lakes and rivers
Authors: Forget Marie-Hélène , Carignan Richard , Hudon Christiane
Published: July 2009

Primary production, planktonic respiration, bacterial abundance, and chlorophyll a were measured in the epilimnion of two Canadian Shield lakes and in two large rivers to establish their metabolic balance and to contrast oligotrophic and oligo-mesotrophic systems. Pronounced diel respiration cycles were observed in all systems, with a minimum in the morning and a maximum in the evening. Respiration was positively correlated with water temperature, incident light, and chlorophyll a concentration. Diel cycles of chlorophyll a were discernible in both rivers and in the oligo-mesotrophic lake. Our results show that a single morning sampling underestimates both respiration and chlorophyll a, whereas a single sample taken at noon generally agrees better with the average of four daily measurements. In oligotrophic Lac Croche, the photosynthetic parameter αBremained constant throughout the day, whereas PBmincreased by 12.5% between 0600 h and 1300 h. Ignoring the diel community respiration cycle resulted in a ~25% underestimation of daily respiration, whereas ignoring the PBmcycle induced a ~9% underestimation of the daily primary production. The net balance between production (P) and respiration (R) of the oligotrophic lake epilimnion remained positive during two summers, and the P:R ratio showed net autotrophy for all systems except for the oligotrophic river, which was slightly net heterotrophic.
Lead–radium dating of orange roughy (Hoplostethus atlanticus): validation of a centenarian life span
Authors: Andrews Allen H. , Tracey Dianne M. , Dunn Matthew R.
Published: July 2009

Life-span estimates for orange roughy ( Hoplostethus atlanticus ) range from ~20 years to well over 100 years. In this study, an improved lead–radium dating technique provided independent age estimates from sagittal otoliths. This technique used the known properties of radioactivity for lead-210 and radium-226 to determine the validity of fish age estimates. An improvement to lead–radium dating using mass spectrometry allowed the use of smaller samples than previously possible; therefore, an application was made to otolith cores, the first few years of otolith growth. This approach circumvented the use of whole otoliths and alleviated many of the assumptions that were necessary in previous lead–radium dating applications. Hence, it was possible to critically evaluate lead–radium dating as a tool in fish age validation. The measurement of lead–radium ratios for a series of age groups that consisted of otolith cores, grouped based on growth-zone counts from thin sections, showed a high degree of correlation to the expected lead–radium ingrowth curve. This finding provided support for age estimation procedures using thin otolith sectioning. As independent estimates of age, the results indicated that fish in the oldest age group were at least 93 years old, providing robust support for a centenarian life span.
Ontogenetic niche shifts and resource partitioning of lake trout morphotypes
Authors: Zimmerman Mara S. , Schmidt Stephanie N. , Krueger Charles C. , Vander Zanden M. Jake , Eshenroder Randy L.
Published: July 2009

Resource polymorphisms are widely observed in fishes; however, ontogenetic contributions to morphological and ecological differences are poorly understood. This study examined whether ontogenetic changes in niche partitioning could explain morphological and buoyancy differences between lake trout ( Salvelinus namaycush ) morphotypes in Great Slave Lake (Northwest Territories, Canada). Morphometric analysis, buoyancy, capture depth, diet, and stable isotope data were used in concert to determine whether (i) differences occur in small, as well as large, lake trout, (ii) ontogenetic changes in morphology and buoyancy correlate with shifts in depth or diet, and (iii) a subset of small trout, putatively identified as “humpers”, are distinct from other morphotypes. Ontogenetic changes in lake trout morphology were associated with an ecological shift between benthic and pelagic feeding. Resource partitioning between lean and siscowet-like trout occurred within benthic (small trout) and pelagic (large trout) habitats. The humper subset did not differ from small siscowet-like trout. By combining multiple methods and an ontogenetic perspective, our study provides novel perspectives on resource polymorphisms in large, deep lakes and on existing interpretations of stable isotope data from large lakes in general.
Reduced swimming performance and increased growth in domesticated rainbow trout, Oncorhynchus mykiss
Authors: Reinbold Drew , Thorgaard Gary H. , Carter Patrick A.
Published: July 2009

Domesticated populations of rainbow trout ( Oncorhynchus mykiss ) probably have been selected for high growth rates and large body size, which may have resulted in reduced sprint swimming performance. We hypothesized that more domesticated populations of rainbow trout would have higher growth rates and larger body size, but slower swim speed, relative to semiwild populations. We tested this hypothesis by measuring body mass, body length, and sprint swim speed multiple times over 92 days in progeny from crosses between males from three clonal lines and an outbred female. We found significantly higher body masses and significantly slower swim speeds in the highly domesticated Arlee and Hot Creek progeny groups compared with the semiwild Swanson hybrid progeny group, supporting our hypothesis. Growth rates also differed significantly among groups, but at the ages measured, the Swanson hybrid progeny had an intermediate growth rate. However, given the differences in body mass, either growth rates were higher in the more domesticated progeny groups at young unmeasured ages and (or) they hatched at a significantly larger body mass than the semiwild Swanson hybrid.
Hypoxia-induced growth limitation of juvenile fishes in an estuarine nursery: assessment of small-scale temporal dynamics using RNA:DNA
Authors: Stierhoff Kevin L. , Targett Timothy E. , Power James H.
Published: July 2009

The ratio of RNA to DNA (RNA:DNA) in white muscle tissue of juvenile summer flounder ( Paralichthys dentatus ) and weakfish ( Cynoscion regalis ) was used as a proxy for recent growth rate in an estuarine nursery. Variability in RNA:DNA was examined relative to temporal changes in temperature and dissolved oxygen (DO). Initial laboratory experiments indicated (i) a strong positive relationship between RNA:DNA and growth rate, (ii) a rapid response of RNA:DNA to changes in feeding, and (iii) no effect of hypoxia on the relationship between RNA:DNA and growth rate (tested in weakfish only). Diel cycling DO occurred in the nursery throughout the summers of 2002 and 2003. Canonical correlation analysis of field data indicated a strong positive relationship between RNA:DNA and mean DO conditions prior to capture in both species. Correlations were weak or insignificant between stomach content mass (an index of feeding) and mean DO and between RNA:DNA and stomach content mass and DO variability. These results suggest a strong functional relationship between DO concentration and the growth rate of juvenile fishes in an estuarine nursery. Furthermore, growth rates of wild-caught fishes (estimated from RNA:DNA) appear to be more negatively impacted by diel cycling hypoxia than would be expected from published laboratory data.
Experimental measurement of hydrosystem-induced delayed mortality in juvenile Snake River spring Chinook salmon (Oncorhynchus tshawytscha) using a large-scale acoustic array
Authors: Rechisky Erin L. , Welch David W. , Porter Aswea D. , Jacobs Melinda C. , Ladouceur Adrian
Published: July 2009

Out-migrating Snake River salmon smolts must pass eight major hydro dams before reaching the Pacific Ocean. Direct mortality at the dams is generally low; however, the cumulative stress caused by dam passage is hypothesized to result in delayed mortality, which occurs beyond the impounded section of the river. We tested the delayed mortality hypothesis by comparing in-river and early ocean survival of hatchery-origin spring Chinook salmon ( Oncorhynchus tshawytscha ) from the Snake River to a mid-Columbia River population that passes through only four dams and has higher smolt to adult return rates. Smolts >140 mm fork length were implanted with acoustic transmitters and tracked with the Pacific Ocean Shelf Tracking (POST) array to as far as Alaska. There was no detectable difference in survivorship to the first ocean detection line, 274 km beyond the final dam (SSnake = 29% ± 4%, SYakima = 28% ± 5%), indicating that the survival disparity observed in adult return rates may develop later in the marine life history phase. Our study is the first to estimate survival in the coastal ocean and demonstrates the utility of a large-scale array in testing previously intractable hypotheses.
Quantum double and κ-Poincaré symmetries in (2+1)-gravity and Chern–Simons theoryThis paper was presented at the Theory CANADA 4 conference, held at Centre de recherches mathématiques, Montréal, Québec, Canada on 4–7 June 2008.
Authors: Meusburger C.
Published: July 2009

We clarify the role of Drinfeld doubles and κ-Poincaré symmetries in quantized (2+1)-gravity and Chern–Simons theory. We discuss the conditions under which a given Hopf algebra symmetry is compatible with a Chern–Simons theory and determine this compatibility explicitly for the Drinfeld doubles and κ-Poincaré symmetries associated with the isometry groups of (2+1)-gravity. In particular, we show that κ-Poincaré symmetries with a timelike deformation are not directly associated with (2+1)-gravity. The association between these κ-Poincaré symmetries and Chern–Simons theory is possible only in the de Sitter case and the relevant Chern–Simons theory is physically inequivalent to (2+1)-gravity.
Holonomy, decomposability, and relativity1This paper was presented at the Theory CANADA 4 conference, held at Centre de recherches mathématiques, Montréal, Québec, Canada on 4–7 June 2008.
Authors: Brannlund J. , Coley A. , Hervik S.
Published: July 2009

We discuss the geometrical properties of spacetimes in the context of higher dimensional theories of gravity. If the spacetime admits a covariantly constant time-like vector, the spacetime is static and (1+10)-decomposable, where the 10-dimensional transverse space is Riemannian. The second class of solutions consists of spacetimes that admit a covariantly constant light-like vector and belong to the higher dimensional Kundt class of spacetimes. These spacetimes are genuinely Lorentzian and have many mathematical properties quite different from their Riemannian counterparts, which can lead to interesting and novel physics. This paper is a review of results published elsewhere (J. Brannlund, A. Coley, and S. Hervik. Class. Quantum Grav. 25, 195007 (2008)).
A proposal for studying off-shell stability of vacuum geometries in string theoryThis paper was presented at the Theory CANADA 4 conference, held at Centre de recherches mathématiques, Montréal, Québec, Canada on 4–7 June 2008.
Authors: Suneeta V.
Published: July 2009

We briefly review studies of off-shell stability of vacuum geometries in semiclassical gravity. We propose a study of off-shell stability of vacua in string theory by a distinct, though somewhat related approach, by studying their stability under suitable world-sheet sigma model renormalization group (RG) flows. Stability under RG flow is a mathematically well-posed and tractable problem in many cases, as we illustrate through examples. The advantage is that we can make definite predictions about late time behaviour and endpoints of off-shell processes in string theory.
Axions from heterotic stringThis paper was presented at the Theory CANADA 4 conference, held at Centre de recherches mathématiques, Montréal, Québec, Canada on 4–7 June 2008.
Authors: Dasgupta Keshav , Firouzjahi Hassan , Gwyn Rhiannon
Published: July 2009

We study the axion in a warped heterotic background. It is shown that the axion decay constant, fa, is sensitive to the warped mass scale of the throat. As an explicit model, we construct a novel AdS-like geometry in heterotic string theory. We demonstrate that in this background fa is given by the mass scale of the longest throat in the compactification. The question of obtaining fa within the required bound 109–1012 GeV is reduced to the construction of a throat inside the heterotic string theory compactification with warped mass scale in the above range. This provides a natural mechanism for realising the axion in heterotic string theory.
Regional-scale groundwater flow in a Canadian Shield setting
Authors: Sykes Jonathan F. , Normani Stefano D. , Jensen Mark R. , Sudicky Edward A.
Published: July 2009

A three-dimensional numerical analysis of a 5734 km2 watershed situated in the Canadian Shield has been conducted to illustrate aspects of regional-scale groundwater flow in a crystalline rock setting. An essential requirement of the analysis is the preservation and accurate description of the complex topography, surface water drainage network, groundwater salinity distribution, and permeability distributions. The postglacial evolution of the groundwater flow system was investigated using the finite difference model SWIFT-III. Robustness was assessed by exploring the sensitivity of groundwater flow to topography, variable matrix permeability distribution models, pore-water salinity, and the dissipation of elevated initial pore pressures that result from ice that overlaid the watershed in the last glacial period. Groundwater flow analyses indicate that freshwater heads in all model layers are highly correlated with the complex surface topography such that the transition from zones of groundwater recharge to zones of discharge occurs over distances that can be relatively short. Shallow flow to a depth of tens of metres dominates the overall water balance, and the length of flow paths is relatively short. The analyses of this study indicate that the flow in deeper rock is not regional but rather is a subdued reflection of the local-scale surface topography.
Measuring shear and compression wave velocities of soil using bender–extender elements
Authors: Leong E. C. , Cahyadi J. , Rahardjo H.
Published: July 2009

Piezoceramic elements have been used for laboratory measurement of wave velocity in soil and rock specimens. Shear-wave piezoceramic elements (bender elements) are commonly used to measure shear wave velocity for the determination of small-strain shear modulus. Compression-wave piezoceramic elements (extender elements), on the other hand, are less commonly used as compression wave velocity is less frequently measured. In this paper, the performance of a pair of bender–extender elements for the determination of both shear and compression wave velocities is examined with respect to the resolution of the recorder, bender–extender element size. and excitation voltage frequency. The evaluation showed that the performance of the bender–extender elements test can be improved by considering the following conditions: (i) the digital oscilloscope used to record the bender–extender element signals should have a high analog to digital (A/D) conversion resolution; (ii) the size of the bender–extender elements plays an important role in the strength and quality of the receiver signal, especially for compression waves; and (iii) using a wave path length to wavelength ratio of 3.33 enables a more reliable determination of shear wave velocity.
Moshinsky atom and density functional theory — A phase space view
Authors: Dahl Jens Peder
Published: July 2009

The problem of two particles in a common harmonic oscillator potential interacting through harmonic oscillator forces is discussed in the Weyl–Wigner phase-space representation. The Wigner function of the system is an ordinary function of the phase-space constants of the motion. The density functional description of the system is touched upon. The functional that determines the confining harmonic potential from the particle density is also an ordinary function.
An implementation of the conductor-like screening model of solvation within the Amsterdam density functional package — Part II. COSMO for real solvents
Authors: Pye Cory C. , Ziegler Tom , van Lenthe Erik , Louwen Jaap N.
Published: July 2009

The conductor-like screening model for real solvents (COSMO-RS) has been implemented in the Amsterdam density functional program. The surface building routines now allow for finer discretization of the GEPOL-based surfaces, and an additional surface due to Delley has been incorporated. One problem identified is the need for accurate density fitting in the region of the surface points. Another difficulty is the need to explicitly state for which atoms the hydrogen-bonding term applies. We present some vapour–liquid equilibrium curves of binary solvent systems to demonstrate the utility of the method.