ON THE DYNAMICS OF COMMERCIAL FISHING AND PARAMETER IDENTIFICATION

This paper has two main objectives. The first is to develop a dynamic model of commercial fisheries different from most existing models that assume optimizing behavior. The industry is assumed to have a well-defined index of performance. Based upon this index, the decision to invest or not is made. We do not, however, assume that the industry or firm is efficient or optimal in its operations. The second is that a new approach of fitting model dynamics to time series data is employed to simultaneously estimate the poorly known initial conditions and parameters of nonlinear fisheries dynamics. The approach is a data assimilation technique known as the variational adjoint method. Estimation of the poorly known initial conditions is one of the attractive features of the variational adjoint method.Resource /Energy Economics and Policy,

Continuous harvesting costs in sole-owner fisheries with increasing marginal returns

We develop a bioeconomic model to analyze a sole-owner fishery with fixed costs as well as a continuous cost function for the generalized Cobb-Douglas production function with increasing marginal returns to effort level. On the basis of data from the North Sea herring fishery, we analyze the consequences of the combined effects of increasing marginal returns and fixed costs. We find that regardless of the magnitude of the fixed costs, cyclical policies can be optimal instead of the optimal steady state equilibrium advocated in much of the existing literature. We also show that the risk of stock collapse increases significantly with increasing fixed costs as this implies higher period cycles which is a quite counterintuitive result as higher costs usually are considered to have a conservative effect on resources.Bioeconomic modelling; Stock collapse; Fixed costs; Pulse fishing; Cyclical dynamics; Increasing marginal returns

Off-World Mental Health:Considerations for the Design of Well-being-Supportive Technologies for Deep Space Exploration

During future long-duration space exploration missions, humans will be exposed to combinations of extreme physical, psychological, and interpersonal demands. These demands create risks for the safety, performance, health, and well-being of both individuals and crew. The communication latency in deep space means that explorers will increasingly have to operate independently and take responsibility for their own self-care and self-management. At present, several research programs are focused on developing and testing digital technologies and countermeasures that support the effective functioning of deep space crews. Although promising, these initiatives have been stimulated mostly by technological opportunity rather than cogent theory. In this perspective, we argue that digital technologies developed for spaceflight should be informed by well-being–supportive design principles and be cognizant of broader conversations around the development and use of digital health applications, especially pertaining to issues of autonomy, privacy, and trust. These issues are important for designing potentially mission-critical health technologies and may be determining factors in the safe and successful completion of future off-world endeavors.publishedVersio

Can legume systeny be useful in guiding the introgression of wild genes into cultivated peanut?

Edição dos resumos do Workshop, Porto Alegre, RS, 2007

Can legume synteny be useful in guiding the introgression of wild genes into cultivated peanut?

Edição do International Workshop Integrating Genomics Into Plant Breeding, Porto Alegre, out. 2007

Profiles of resilient psychosocial function during three isolated ski expeditions in the High Arctic

To successfully complete a Polar expedition individuals and teams must respond resiliently to the environmental, psychological, and social demands they face. In this study we examined profiles of resilient function in seven people from three expeditions in the High Arctic. Using a structured daily diary, participants reported on experiences of physical health (morning and evening), affect, team cohesion, performance, and potential explanatory factors including sleep, demand appraisals, events, and coping strategies. Notable intra- and inter-individual variability was observed in daily reports and all profiles could be interpreted as representing resilient function. A number of significant relationships were found between markers of resilient physical and psychosocial function and potential explanatory variables. For example, there was much more daily variability in an individual's reporting of positive affect than prior research might imply, and what prior research designs could capture. Further, while negative affect tended to remain low and stable, our findings reveal that even minor and infrequent increases in negative emotions were significantly associated with other variables in the network. Finally, across the expedition period individual coping resources consistently exceeded demands, suggesting that individuals viewed the expedition as a challenge and not a threat. More broadly, these findings inform efforts to monitor, and maintain resilience when operating in Polar and other extreme settings

An analysis of synteny of Arachis with Lotus and Medicago sheds new light on the structure, stability and evolution of legume genomes

<p>Abstract</p> <p>Background</p> <p>Most agriculturally important legumes fall within two sub-clades of the Papilionoid legumes: the Phaseoloids and Galegoids, which diverged about 50 Mya. The Phaseoloids are mostly tropical and include crops such as common bean and soybean. The Galegoids are mostly temperate and include clover, fava bean and the model legumes <it>Lotus </it>and <it>Medicago </it>(both with substantially sequenced genomes). In contrast, peanut (<it>Arachis hypogaea</it>) falls in the Dalbergioid clade which is more basal in its divergence within the Papilionoids. The aim of this work was to integrate the genetic map of <it>Arachis </it>with <it>Lotus </it>and <it>Medicago </it>and improve our understanding of the <it>Arachis </it>genome and legume genomes in general. To do this we placed on the <it>Arachis </it>map, comparative anchor markers defined using a previously described bioinformatics pipeline. Also we investigated the possible role of transposons in the patterns of synteny that were observed.</p> <p>Results</p> <p>The <it>Arachis </it>genetic map was substantially aligned with <it>Lotus </it>and <it>Medicago </it>with most synteny blocks presenting a single main affinity to each genome. This indicates that the last common whole genome duplication within the Papilionoid legumes predated the divergence of <it>Arachis </it>from the Galegoids and Phaseoloids sufficiently that the common ancestral genome was substantially diploidized. The <it>Arachis </it>and model legume genomes comparison made here, together with a previously published comparison of <it>Lotus </it>and <it>Medicago </it>allowed all possible <it>Arachis-Lotus-Medicago </it>species by species comparisons to be made and genome syntenies observed. Distinct conserved synteny blocks and non-conserved regions were present in all genome comparisons, implying that certain legume genomic regions are consistently more stable during evolution than others. We found that in <it>Medicago </it>and possibly also in <it>Lotus</it>, retrotransposons tend to be more frequent in the variable regions. Furthermore, while these variable regions generally have lower densities of single copy genes than the more conserved regions, some harbor high densities of the fast evolving disease resistance genes.</p> <p>Conclusion</p> <p>We suggest that gene space in Papilionoids may be divided into two broadly defined components: more conserved regions which tend to have low retrotransposon densities and are relatively stable during evolution; and variable regions that tend to have high retrotransposon densities, and whose frequent restructuring may fuel the evolution of some gene families.</p

Efficient unfolding pattern recognition in single molecule force spectroscopy data

BackgroundSingle-molecule force spectroscopy (SMFS) is a technique that measures the force necessary to unfold a protein. SMFS experiments generate Force-Distance (F-D) curves. A statistical analysis of a set of F-D curves reveals different unfolding pathways. Information on protein structure, conformation, functional states, and inter- and intra-molecular interactions can be derived.ResultsIn the present work, we propose a pattern recognition algorithm and apply our algorithm to datasets from SMFS experiments on the membrane protein bacterioRhodopsin (bR). We discuss the unfolding pathways found in bR, which are characterised by main peaks and side peaks. A main peak is the result of the pairwise unfolding of the transmembrane helices. In contrast, a side peak is an unfolding event in the alpha-helix or other secondary structural element. The algorithm is capable of detecting side peaks along with main peaks.Therefore, we can detect the individual unfolding pathway as the sequence of events labeled with their occurrences and co-occurrences special to bR\u27s unfolding pathway. We find that side peaks do not co-occur with one another in curves as frequently as main peaks do, which may imply a synergistic effect occurring between helices. While main peaks co-occur as pairs in at least 50% of curves, the side peaks co-occur with one another in less than 10% of curves. Moreover, the algorithm runtime scales well as the dataset size increases.ConclusionsOur algorithm satisfies the requirements of an automated methodology that combines high accuracy with efficiency in analyzing SMFS datasets. The algorithm tackles the force spectroscopy analysis bottleneck leading to more consistent and reproducible results