Population Dynamics of Long-tailed Ducks Breeding on the Yukon-Kuskokwim Delta, Alaska

Population estimates for long-tailed ducks in North America have declined by nearly 50% over the past 30 years. Life history and population dynamics of this species are difficult to ascertain, because the birds nest at low densities across a broad range of habitat types. Between 1991 and 2004, we collected information on productivity and survival of long-tailed ducks at three locations on the Yukon-Kuskokwim Delta. Clutch size averaged 7.1 eggs, and nesting success averaged 30%. Duckling survival to 30 days old averaged 10% but was highly variable among years, ranging from 0% to 25%. Apparent annual survival of adult females based on mark-recapture of nesting females was estimated at 74%. We combined these estimates of survival and productivity into a matrix-based population model, which predicted an annual population decline of 19%. Elasticities indicated that population growth rate (?) was most sensitive to changes in adult female survival. Further, the relatively high sensitivity of ? to duckling survival suggests that low duckling survival may be a bottleneck to productivity in some years. These data represent the first attempt to synthesize a population model for this species. Although our analyses were hampered by the small sample sizes inherent in studying a dispersed nesting species, our model provides a basis for management actions and can be enhanced as additional data become available.Les estimations de populations d’hareldes kakawis en Amérique du Nord ont chuté de près de 50 pour cent ces 30 dernières années. Le cycle biologique et la dynamique des populations de cette espèce sont difficiles à établir car ces oiseaux nichent moyennant de faibles densités dans une vaste gamme d’habitats. De 1991 à 2004, nous avons recueilli des données sur la productivité et la survie des hareldes kakawis à trois emplacements du delta Yukon-Kuskokwim. Les couvées atteignaient 7,1 oeufs en moyenne, tandis que le succès de reproduction s’établissait généralement à 30 pour cent. En moyenne, 10 pour cent des jeunes canards survivaient jusqu’à l’âge de 30 jours, mais ce taux variait beaucoup d’une année à l’autre, allant de 0 pour cent à 25 pour cent. Annuellement, d’après la méthode par marquage et recapture des femelles nidificatrices, la survie apparente des femelles adultes était évaluée à 74 pour cent. Nous avons combiné ces estimations de survie et de productivité dans un modèle de population matriciel, ce qui a permis de prédire un déclin de population annuel de 19 pour cent. Selon les élasticités, le taux de croissance de la population (?) était plus sensible aux changements dans le cas de la survie des femelles adultes. Par ailleurs, la sensibilité relativement élevée du ? par rapport à la survie des jeunes canards laisse croire que le faible taux de survie des jeunes canards pourrait présenter une embûche en matière de productivité d’ici quelques années. Ces données représentent la première tentative de synthèse d’un modèle de population pour cette espèce. Bien que nos analyses aient été gênées par la petite taille des échantillons inhérente à l’étude d’espèces de nidification dispersées, notre modèle fournit un fondement permettant d’aboutir à des mesures de gestion en plus de présenter la possibilité d’être amélioré au fur et à mesure que des données supplémentaires sont disponibles

Monitoring buried infrastructure deformation using acoustic emissions

Deformation of soil bodies and buried infrastructure elements (i.e. soil-structure systems) generates acoustic emission (AE). Detecting this AE by coupling sensors to buried structural elements can provide information on asset condition and early warning of accelerating deformation behaviour. A novel approach for deformation monitoring of buried steel infrastructure (e.g. pipes and pile foundations) using AE is described in the paper. The monitoring concept employs pre-existing, or newly built, buried steel infrastructure assets as waveguides. The propagation of AE through example pipes acting as waveguides has been modelled computationally using the program Disperse. A parametric study has been used to investigate the influence of key variables such as burial depth, surrounding soil type, internal environment, pipe diameter, wall thickness, frequency and mode type upon AE propagation and attenuation. Understanding the propagation and attenuation of AE is of fundamental importance for development of a monitoring strategy and specifically to determine the spacing of sensors deployed along infrastructure elements. The generation of AE due to soil-structure interaction mechanisms has been investigated using a programme of large direct shear tests of soil against steel plates under a range of conditions (e.g. soil type, plate surface conditions, stress level, strain rate). New, fundamental understanding of AE generation and propagation in buried infrastructure is enabling a framework to be developed for interpreting asset condition from AE measurements. The paper will introduce the approach developed, describe the parametric study of AE propagation and attenuation presenting example results, and show typical AE behaviour for soil-structure interaction obtained in the large shear tests. The implications for design of a monitoring framework will be discussed

Acoustic emission monitoring in geotechnical element tests

Acoustic emission (AE) is high-frequency noise (>10kHz) generated by deforming materials. AE is widely used in many industries for non-destructive testing and evaluation; however, it is seldom used in geotechnical engineering, despite evidence of the benefits, because AE generated by particulate materials is highly complex and difficult to measure and interpret. This paper demonstrates that innovative AE instrumentation and measurement can enhance insights into geotechnical element tests. Results from a programme of triaxial compression and shear, large direct-shear and large permeameter experiments show that AE can be used to characterise mechanical and hydromechanical behaviour of soils and soil-structure interaction, including: dilative shear behaviour; transitions from pre- to post-peak shear strength; changes in strain rates; isotropic compression; unload-reload cycles of compression and shear; and seepage-induced internal instability phenomena

Pyridyl anchored indolium dyes for the p-type dye sensitized solar cell

Three new thiophenyl bridged triarylamine-donor based dyes with pyridyl anchoring groups and indolium acceptors have been synthesized and studied as sensitizers for the p-type dye-sensitized solar cell (p-DSSC). Compared to known dicyano and pyridinium dyes with the same triarylamine cores, these new sensitizers have broadened and red-shifted UV–vis absorption spectra, with high extinction coefficients and absorption extending beyond 700 nm. TD-DFT calculations on the indolium family indicate that these dyes combine strong donor acceptor communication, with a high degree of charge separation in the excited state – an ideal combination for sensitizer dyes. The phenylpyridyl anchored bis-indolium gives the highest power conversion efficiency (0.097%) through a short circuit photocurrent (JSC) of 3.04 mA cm−2, open circuit voltage (VOC) of 97 mV and fill factor of 36%. This exceeds the performance of the P1 reference dye in this study, and represents the best performance so far for a cationic, pyridine anchored p-DSSC dye

Dangerous liaisons: youth sport, citizenship and intergenerational mistrust

This is an Accepted Manuscript of an article published by Taylor & Francis in International Journal of Sport Policy and Politics on 24/3/2014, available online: DOI 10.1080/19406940.2014.896390This paper reflects on and offers a critical analysis of the relationship between youth sport and citizenship development, in practice and in the UK policy context of sports coaching and physical education. While deploying data and insights from a recently completed research project in England, which identified substantial tensions in intergenerational relationships in sport and coaching, the argument and analysis also invokes wider international concerns and more generally applicable implications for policy and practice. Drawing heuristically upon the philosophy of Dewey (2007 [1916]), it is recognised that the concept of citizenship as a form of social practice should seek to encourage the development of complementary traits and dispositions in young people. To develop socially and educationally thus entails engagement in meaningful social and cultural activity, of which one potentially significant component is participation in youth sport, both within and outside formal education. However, it is argued that any confident assumption that sporting and coaching contexts will necessarily foster positive traits and dispositions in young people should be considered dubious and misplaced. Deploying a Lacanian (1981) perspective to interpret our data, we contend that ‘liaisons’ and interactions between coaches and young people are often treated suspiciously, and regarded as potentially ‘dangerous’

A panchromatic, near infrared Ir(III) emitter bearing a tripodal C^N^C ligand as a dye for dye-sensitized solar cells

C.H. acknowledges the Région Bretagne, France for funding. EZ-C acknowledges the University of St Andrews and EPSRC (EP/M02105X/1) for financial support. EAG and HVF thank the ERC for a Starting Grant (p-TYPE, 715354).The synthesis of a new complex of the form [Ir(C^N^C)(N^N)Cl] [where C^N^C = 2-(bis(4-(tert-butyl)phenyl)methyl)pyridinato (dtBubnpy, L1 ) and N^N is diethyl [2,2'-bipyridine]-4,4'-dicarboxylate (deeb)] is reported. The crystal structure reveals an unusual tripodal tridentate C^N^C ligand forming three six-membered rings around the iridium center. The photophysical and electrochemical properties suggest the use of this complex as a dye in dye-sensitized solar cells. Time-Dependent Density Functional Theory (TD-DFT) calculations have been used to reveal the nature of the excited-states.PostprintPeer reviewe

Quantitative trait loci mapping reveals candidate pathways regulating cell cycle duration in Plasmodium falciparum

<p>Abstract</p> <p>Background</p> <p>Elevated parasite biomass in the human red blood cells can lead to increased malaria morbidity. The genes and mechanisms regulating growth and development of <it>Plasmodium </it><it>falciparum </it>through its erythrocytic cycle are not well understood. We previously showed that strains HB3 and Dd2 diverge in their proliferation rates, and here use quantitative trait loci mapping in 34 progeny from a cross between these parent clones along with integrative bioinformatics to identify genetic loci and candidate genes that control divergences in cell cycle duration.</p> <p>Results</p> <p>Genetic mapping of cell cycle duration revealed a four-locus genetic model, including a major genetic effect on chromosome 12, which accounts for 75% of the inherited phenotype variation. These QTL span 165 genes, the majority of which have no predicted function based on homology. We present a method to systematically prioritize candidate genes using the extensive sequence and transcriptional information available for the parent lines. Putative functions were assigned to the prioritized genes based on protein interaction networks and expression eQTL from our earlier study. DNA metabolism or antigenic variation functional categories were enriched among our prioritized candidate genes. Genes were then analyzed to determine if they interact with cyclins or other proteins known to be involved in the regulation of cell cycle.</p> <p>Conclusions</p> <p>We show that the divergent proliferation rate between a drug resistant and drug sensitive parent clone is under genetic regulation and is segregating as a complex trait in 34 progeny. We map a major locus along with additional secondary effects, and use the wealth of genome data to identify key candidate genes. Of particular interest are a nucleosome assembly protein (PFL0185c), a Zinc finger transcription factor (PFL0465c) both on chromosome 12 and a ribosomal protein L7Ae-related on chromosome 4 (PFD0960c).</p

Genetic Effects at Pleiotropic Loci Are Context-Dependent with Consequences for the Maintenance of Genetic Variation in Populations

Context-dependent genetic effects, including genotype-by-environment and genotype-by-sex interactions, are a potential mechanism by which genetic variation of complex traits is maintained in populations. Pleiotropic genetic effects are also thought to play an important role in evolution, reflecting functional and developmental relationships among traits. We examine context-dependent genetic effects at pleiotropic loci associated with normal variation in multiple metabolic syndrome (MetS) components (obesity, dyslipidemia, and diabetes-related traits). MetS prevalence is increasing in Western societies and, while environmental in origin, presents substantial variation in individual response. We identify 23 pleiotropic MetS quantitative trait loci (QTL) in an F16 advanced intercross between the LG/J and SM/J inbred mouse strains (Wustl:LG,SM-G16; n = 1002). Half of each family was fed a high-fat diet and half fed a low-fat diet; and additive, dominance, and parent-of-origin imprinting genotypic effects were examined in animals partitioned into sex, diet, and sex-by-diet cohorts. We examine the context-dependency of the underlying additive, dominance, and imprinting genetic effects of the traits associated with these pleiotropic QTL. Further, we examine sequence polymorphisms (SNPs) between LG/J and SM/J as well as differential expression of positional candidate genes in these regions. We show that genetic associations are different in different sex, diet, and sex-by-diet settings. We also show that over- or underdominance and ecological cross-over interactions for single phenotypes may not be common, however multidimensional synthetic phenotypes at loci with pleiotropic effects can produce situations that favor the maintenance of genetic variation in populations. Our findings have important implications for evolution and the notion of personalized medicine