176 research outputs found
Process-based modelling of decadal trends in growth, survival, and smolting of wild salmon (Salmo salar) parr in a Scottish upland stream
This paper reports a new model of the freshwater stages of an anadromous fish, at the core of which is a stochastic description of the size-at-age dynamics of a growing cohort. Emigration is assumed to require the individual to exceed a threshold size at a critical time of year, thus making the distributions of survival to, and age at, smolting emergent properties of the model. The model is applied to a long-term data set on juvenile Atlantic salmon (Salmo salar) in the Girnock Burn, Scotland, to understand the role played by decadal temperature trends in generating changes in smolt production and age distribution. We conclude that changes in age at smolting are compatible with causation by shifts in the temperature regime. However, the large attenuation between a dramatic fall in spawner numbers and a relatively minor diminution in total smolt production does not result from the physiological effects of temperature but is rather a result of strongly density-dependent mortality between the deposition of ova and the appearance of catchable fry the following summer
Heritability estimation via molecular pedigree reconstruction in a wild fish population reveals substantial evolutionary potential for sea age at maturity, but not size within age classes
While evolutionary responses require heritable variation, estimates of heritability (h(2)) from wild fish populations remain rare. A 20-year molecular pedigree for a wild Scottish population of Atlantic salmon (Salmo salar) was used to investigate genetic contributions to (co) variation in two important, correlated, phenotypic traits: "sea age" (number of winters spent at sea prior to spawning) and size-at-maturity (body length just prior to spawning). Sea age was strongly heritable (h(2) = 0.51) and size exhibited moderate heritability (h(2) = 0.27). A very strong genetic correlation (r(G) = 0.96) between these traits implied the same functional loci must underpin variation in each. Indeed, body size within sea ages had much lower heritability that did not differ significantly from zero. Thus, within wild S. salar populations, temporal changes in sea age composition could reflect evolutionary responses, whereas rapid changes of body size within sea ages are more likely due to phenotypic plasticity. These inheritance patterns will influence the scope of evolutionary responses to factors such as harvest or climate change and, hence, have management implications for salmonid populations comprising a mix of sea ages.Peer reviewe
Fossil data support a pre-Cretaceous origin of flowering plants
Data and scripts associated with the paper. Updated version of the code will be available here: https://github.com/dsilvestro/rootBB
High-Alpha Research Vehicle (HARV) longitudinal controller: Design, analyses, and simulation resultss
This paper describes the design, analysis, and nonlinear simulation results (batch and piloted) for a longitudinal controller which is scheduled to be flight-tested on the High-Alpha Research Vehicle (HARV). The HARV is an F-18 airplane modified for and equipped with multi-axis thrust vectoring. The paper includes a description of the facilities, a detailed review of the feedback controller design, linear analysis results of the feedback controller, a description of the feed-forward controller design, nonlinear batch simulation results, and piloted simulation results. Batch simulation results include maximum pitch stick agility responses, angle of attack alpha captures, and alpha regulation for full lateral stick rolls at several alpha's. Piloted simulation results include task descriptions for several types of maneuvers, task guidelines, the corresponding Cooper-Harper ratings from three test pilots, and some pilot comments. The ratings show that desirable criteria are achieved for almost all of the piloted simulation tasks
Cytological and transcript analyses reveal fat and lazy persister-like bacilli in tuberculous sputum
As nonreplicating tubercle bacilli are tolerant to the cidal action of antibiotics and resistant to multiple stresses, identification of this persister-like population of tubercle bacilli in sputum presents exciting and tractable new opportunities to investigate both responses to chemotherapy and the transmission of tuberculosis
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Motivating Emotional Intelligence: A Reinforcement Sensitivity Theory (RST) Perspective
Trait emotional intelligence (trait EI) is generally associated with positive outcomes and can inform clinical and social interventions. We investigated the sub-factors of trait EI: Wellbeing, Self-control, Emotionality, and Sociability, in the context of the Reinforcement Sensitivity Theory (RST) of motivation. In Study 1, participants (N = 247) completed Carver and White’s (1994) BIS/BAS scales and a measure of trait EI. All EI sub-factors were positively associated with BAS Drive and negatively with BIS. Study 2 (N = 382) employed a new questionnaire based on revised RST (Corr & Cooper, 2016). All trait EI factors were positively associated with BAS Goal-Drive Persistence and Reward Interest, and negatively with the BIS. Self-control showed negative associations with BAS Impulsivity and was the only factor not to correlate with BAS Reward Reactivity. Results suggest that high trait EI individuals are goal driven, sensitive to reward and lower in avoidance motivation and negative emotion. This motivational basis to trait EI further explicates its structure
The XMM Cluster Survey: testing chameleon gravity using the profiles of clusters
The chameleon gravity model postulates the existence of a scalar field that couples with matter to mediate a fifth force. If it exists, this fifth force would influence the hot X-ray emitting gas filling the potential wells of galaxy clusters. However, it would not influence the clusters weak lensing signal. Therefore, by comparing X-ray and weak lensing profiles, one can place upper limits on the strength of a fifth force. This technique has been attempted before using a single, nearby cluster (Coma, z = 0.02). Here we apply the technique to the stacked profiles of 58 clusters at higher redshifts (0.1 < z < 1.2), including 12 new to the literature, using X-ray data from the XMM Cluster Survey and weak lensing data from the Canada-France-Hawaii-Telescope Lensing Survey. Using a multiparameter Markov chain Monte Carlo analysis, we constrain the two chameleon gravity parameters (beta and phi∞). Our fits are consistent with general relativity, not requiring a fifth force. In the special case of f(R) gravity (where beta = &surd;{1/6}), we set an upper limit on the background field amplitude today of |fR0| < 6 × 10-5 (95 per cent CL). This is one of the strongest constraints to date on |fR0| on cosmological scales. We hope to improve this constraint in future by extending the study to hundreds of clusters using data from the Dark Energy Survey
Probing host pathogen cross-talk by transcriptional profiling of both Mycobacterium tuberculosis and infected human dendritic cells and macrophages
This study provides the proof of principle that probing the host and the microbe transcriptomes simultaneously is a valuable means to accessing unique information on host pathogen interactions. Our results also underline the extraordinary plasticity of host cell and pathogen responses to infection, and provide a solid framework to further understand the complex mechanisms involved in immunity to M. tuberculosis and in mycobacterial adaptation to different intracellular environments
Temporal changes in kin structure through a population cycle in a territorial bird, the red grouse Lagopus lagopus scoticus
Populations of red grouse (Lagopus lagopus scoticus) undergo regular multiannual cycles in abundance. The 'kinship hypothesis' posits that such cycles are caused by changes in kin structure among territorial males producing delayed density-dependent changes in aggressiveness, which in turn influence recruitment and regulate density. The kinship hypothesis makes several specific predictions about the levels of kinship, aggressiveness and recruitment through a population cycle: (i) kin structure will build up during the increase phase of a cycle, but break down prior to peak density; (ii) kin structure influences aggressiveness, such that there will be a negative relationship between kinship and aggressiveness over the years; (iii) as aggressiveness regulates recruitment and density, there will be a negative relationship between aggressiveness in one year and both recruitment and density in the next; (iv) as kin structure influences recruitment via an affect on aggressiveness, there will be a positive relationship between kinship in one year and recruitment the next. Here we test these predictions through the course of an 8-year cycle in a natural population of red grouse in northeast Scotland, using microsatellite DNA markers to resolve changing patterns of kin structure, and supra-orbital comb height of grouse as an index of aggressiveness. Both kin structure and aggressiveness were dynamic through the course of the cycle, and changing patterns were entirely consistent with the expectations of the kinship hypothesis. Results are discussed in relation to potential drivers of population regulation and implications of dynamic kin structure for population genetics.This work was funded by the Natural Environment Research Council, the European Union, University of Aberdeen and the Centre for Ecology & Hydrology.Peer reviewe
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