807 research outputs found
Estimates of survival probabilities for oceanic-stage loggerhead sea turtles (Caretta caretta) in the North Atlantic
Estimates of instantaneous mortality rates (Z) and annual apparent survival probabilities (Φ) were generated from catch-curve analyses for oceanic-stage juvenile loggerheads (Caretta caretta) in the waters of the Azores. Two age distributions were analyzed: the “total sample” of 1600 loggerheads primarily captured by sighting and dipnetting from a variety of vessels in the Azores between 1984 and 1995 and the “tuna sample” of 733 loggerheads (a subset of the total sample) captured by sighting and dipnetting from vessels in the commercial tuna fleet in the Azores between 1990 and 1992. Because loggerhead sea turtles begin to emigrate from oceanic to neritic habitats at age 7, the best estimates of instantaneous mortality rate (0.094) and annual survival probability (0.911) not confounded with permanent emigration were generated for age classes 2 through 6. These estimates must be interpreted with caution because of the assumptions upon which catch-curve analyses are based. However, these are the first directly derived estimates of mortality and survival probabilities for oceanic-stage sea turtles. Estimation of survival probabilities was identified as “an immediate and critical requirement” in 2000 by the Turtle Expert Working Group of the U.S. National Marine Fisheries Service
Multifidelity optimization under uncertainty for a tailless aircraft
This paper presents a multifidelity method for optimization under uncertainty for aerospace problems. In this work, the effectiveness of the method is demonstrated for the robust optimization of a tailless aircraft that is based on the Boeing Insitu ScanEagle. Aircraft design is often affected by uncertainties in manufacturing and operating conditions. Accounting for uncertainties during optimization ensures a robust design that is more likely to meet performance requirements. Designing robust systems can be computationally prohibitive due to the numerous evaluations of expensive-to-evaluate high-fidelity numerical models required to estimate system-level statistics at each optimization iteration. This work uses a multifidelity Monte Carlo approach to estimate the mean and the variance of the system outputs for robust optimization. The method uses control variates to exploit multiple fidelities and optimally allocates resources to different fidelities to minimize the variance in the estimates for a given budget. The results for the ScanEagle application show that the proposed multifidelity method achieves substantial speed-ups as compared to a regular Monte-Carlo-based robust optimization.United States. Air Force. Office of Scientific Research. Multidisciplinary University Research Initiative (FA9550-15-1-0038
Compensatory growth in oceanic loggerhead sea turtles: response to a stochastic environment
Compensatory growth (CG, accelerated growth that may occur when an
organism that has grown at a reduced rate as a result of suboptimal environmental
conditions is exposed to better conditions) is considered an adaptation to variable en vironments. Although documented thoroughly under captive conditions, CG has rarely
been studied in wild populations. In their first years of life, oceanic-stage loggerhead
sea turtles (Caretta caretta) have relatively little control over their geographic position
or movements and thus have an extremely stochastic lifestyle with great variation in
food availability and temperature. This environmental variation results in variable
growth rates. We evaluate somatic growth functions of oceanic-stage loggerheads from
the eastern Atlantic based on skeletochronology that allowed us to assign age and cohort
to each individual. We demonstrate CG in these turtles based on three different analytical
approaches: changes in coefficients of variation in size-at-age, generalized additive
model regression analyses of somatic growth, and linear regression of age-specific
growth rates. As a result of CG, variation in size-at-age in these juvenile loggerheads
is substantially reduced. Thus, size is a better predictor of age than expected based on
variation in growth rates. CG decreases with age, apparently as loggerheads gain greater
control over their movements. In addition, we have evaluated for the first time in wild
sea turtles the time-dependent nature of somatic growth by distinguishing among age,
year, and cohort effects using a mixed longitudinal sampling design with assigned-age
individuals. Age and year had significant effects on growth rates, but there was no
significant cohort effect. Our results address critical gaps in knowledge of the demog raphy of this endangered species.info:eu-repo/semantics/publishedVersio
Transatlantic developmental migrations of loggerhead sea turtles demonstrated by mtDNA sequence analysis
Molecular markers based on mitochondrial (mt) DNA control region se quences were used to test the hypothesis that juvenile loggerhead sea turtles (Caretta
caretta) in pelagic habitats of the eastern Atlantic are derived from nesting populations in
the western Atlantic. We compared mtDNA haplotypes from 131 pelagic juvenile turtles
(79 from the Azores and 52 from Madeira) to mtDNA haplotypes observed in major nesting
colonies of the Atlantic Ocean and Mediterranean Sea. A subset of 121 pelagic samples
(92%) contained haplotypes that match mtDNA sequences observed in nesting colonies.
Maximum likelihood analyses (UCON, SHADRACQ) estimate that 100% of these pelagic
juveniles are from the nesting populations in the southeastern United States and adjacent
Yucatan Peninsula, Mexico. Estimated contributions from nesting populations in south
Florida (0.71, 0.72), northern Florida to North Carolina (0.19, 0.17), and Quintana Roo,
Mexico (0.11, 0.10) are consistent with the relative size of these nesting aggregates. No
contribution was detected from nesting colonies in the Mediterranean (Greece) or South
Atlantic (Brazil), although samples sizes are insufficient to exclude these locations with
finality. The link between west Atlantic nesting colonies and east Atlantic feeding grounds
provides a more complete scientific basis for assessing the impact of subadult mortality in
oceanic fisheries. Demographic models for loggerhead turtles in the western Atlantic can
now be improved by incorporating growth and mortality data from juvenile turtles in pelagic
habitats. These data demonstrate that the appropriate scale for loggerhead turtle conservation
efforts is vastly larger than the current scale of management plans based on political
boundaries.info:eu-repo/semantics/publishedVersio
Sea turtles : University of Florida – University of the Azores connection 1984 – present. A review
The loggerhead (Caretta caretta) is the most common sea turtle in the Azores. Since they do not nest in the area, a tagging program was started in the 1980’s to try to discover their origin. The result based on size distribution, suggested that they mainly are coming from beaches in SE United States. A collaboration between University of Florida and the University of the Azores began in 1984 in order to proceed with further research.info:eu-repo/semantics/publishedVersio
The role of plant-associated bacteria, fungi, and viruses in drought stress mitigation.
Abstract: Drought stress is an alarming constraint to plant growth, development, and productivity worldwide. However, plant-associated bacteria, fungi, and viruses can enhance stress resistance and cope with the negative impacts of drought through the induction of various mechanisms, which involve plant biochemical and physiological changes. These mechanisms include osmotic adjustment, antioxidant enzyme enhancement, modification in phytohormonal levels, biofilm production, increased water and nutrient uptake as well as increased gas exchange and water use efficiency. Production of microbial volatile organic compounds (mVOCs) and induction of stress-responsive genes by microbes also play a crucial role in the acquisition of drought tolerance. This review offers a unique exploration of the role of plant-associated microorganisms?plant growth promoting rhizobacteria and mycorrhizae, viruses, and their interactions?in the plant microbiome (or phytobiome) as a whole and their modes of action that mitigate plant drought stress
Correção de fenda palatina traumática associada Ă fratura de mandĂbula em felino: Relato de caso
Quando defeitos palatinos ocasionados por trauma interrompem a separação da cavidade oral e nasal, tĂ©cnicas cirĂşrgicas adequadas sĂŁo essenciais para a reconstrução anatĂ´mica. Relata-se um caso de fenda palatina secundária por trauma e fratura de mandĂbula, sendo a primeira corrigida cirurgicamente utilizando a tĂ©cnica de retalho bipediculado deslizante (tĂ©cnica de Von Langebeck), consistindo no alĂvio com estafilorrafia e redução da fratura com a tĂ©cnica de amarria interdental com resina acrĂlica. As tĂ©cnicas mostraram-se eficazes no fechamento da fenda palatina e redução da fratura, aliadas aos cuidados adequados no pĂłs-operatĂłrio
Diet and lifestyle changes during the COVID-19 pandemic in Ibero-American countries: Argentina, Brazil, Mexico, Peru, and Spain
This study aimed to evaluate changes in dietary and lifestyle habits during the period of confinement due to the first wave of the COVID-19 pandemic in Ibero-American countries. A cross-sectional investigation was conducted with 6,325 participants of both genders (68% women), over 18 years of age and from five countries: Brazil (N = 2,171), Argentina (N = 1,111), Peru (N = 1,174), Mexico (N = 686), and Spain (N = 1,183). Data were collected during the year 2020, between April 01 and June 30 in Spain and between July 13 and September 26, in the other countries studied using a self-administered online survey designed for the assessment of sociodemographic, employment, physical activity, health status, and dietary habits changes. Most participants (61.6%), mainly those from Spain, remained constant, without improving or worsening their pattern of food consumption. Among those who changed, a pattern of better eating choices prevailed (22.7%) in comparison with those who changed toward less healthy choices (15.7%). Argentina and Brazil showed the highest proportion of changes toward a healthier pattern of food consumption. Peruvians and Mexicans were less likely to make healthy changes in food consumption (OR: 0.51; 95% CI: 0.4–0.6 and OR: 0.69; 95% CI: 0.4–0.8, respectively), when compared to Argentinians. Most respondents did not change their pattern of meal consumption, but those who did reduced their consumption of main meals and increased intake of small meals and snacks. Although most participants affirmed to be doing physical activity at home, about one-half reported perception of weight gain. Individuals with alterations in sleep pattern (either by increasing or decreasing sleep time) were more likely to change their diets to a healthier pattern. In contrast, individuals with confirmed diagnosis of COVID-19 and those who reported feeling anxious were more likely to perform changes to a less healthy eating pattern (OR: 1.72; 95% CI: 1.2–2.3 and OR: 1.21; 95% CI: 1.1–1.4, respectively). In conclusion, although most participants remained constant in their eating habits, lifestyle changes and anxiety feelings were reported. Among those who changed patterns of food consumption, healthier choices prevailed, with differences between countries. However, there were alterations in the distribution of meals, with higher consumption of snacks and small meals. These results can be used to guide policies to prevent deleterious consequences that may affect the incidence of chronic diseasesWe acknowledge the National Council for Scientific and Technological Development (CNPq) which provided MCBM a productivity fellowship and the Coordination for the Improvement of Higher Education Personnel (CAPES) which granted OE-M a Ph.D. scholarship. The project developed in Spain was supported by the Program of R&D activities between research groups of the Community of Madrid in Social Sciences and Humanities, co-financed with the European Social Fund (H2019/HUM-5802
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