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The shape gradient is a local sensitivity function defined on the surface of an object which provides the change in a characteristic quantity, or figure of merit, associated with a perturbation to the shape of the object. The shape gradient can be used for gradient-based optimization, sensitivity analysis and tolerance calculations. However, it is generally expensive to compute from finite-difference derivatives for shapes that are described by many parameters, as is the case for typical stellarator geometry. In an accompanying work (Antonsen, Paul & Landreman J. Plasma Phys., vol. 85 (2), 2019), generalized self-adjointness relations are obtained for magnetohydrodynamic (MHD) equilibria. These describe the relation between perturbed equilibria due to changes in the rotational transform or toroidal current profiles, displacements of the plasma boundary, modifications of currents in the vacuum region or the addition of bulk forces. These are applied to efficiently compute the shape gradient of functions of MHD equilibria with an adjoint approach. In this way, the shape derivative with respect to any perturbation applied to the plasma boundary or coil shapes can be computed with only one additional MHD equilibrium solution. We demonstrate that this approach is applicable for several figures of merit of interest for stellarator configuration optimization: the magnetic well, the magnetic ripple on axis, the departure from quasisymmetry, the effective ripple in the low-collisionality
(Nemov et al.Phys. Plasmas, vol. 6 (12), 1999, pp. 4622–4632) and several finite-collisionality neoclassical quantities. Numerical verification of this method is demonstrated for the magnetic well figure of merit with the VMEC code (Hirshman & Whitson Phys. Fluids, vol. 26 (12), 1983, p. 3553) and for the magnetic ripple with modification of the ANIMEC code (Cooper et al.Comput. Phys. Commun., vol. 72 (1), 1992, pp. 1–13). Comparisons with the direct approach demonstrate that, in order to obtain agreement within several per cent, the adjoint approach provides a factor of
in computational savings.
The Minnesota Center for Twin and Family Research (MCTFR) comprises multiple longitudinal, community-representative investigations of twin and adoptive families that focus on psychological adjustment, personality, cognitive ability and brain function, with a special emphasis on substance use and related psychopathology. The MCTFR includes the Minnesota Twin Registry (MTR), a cohort of twins who have completed assessments in middle and older adulthood; the Minnesota Twin Family Study (MTFS) of twins assessed from childhood and adolescence into middle adulthood; the Enrichment Study (ES) of twins oversampled for high risk for substance-use disorders assessed from childhood into young adulthood; the Adolescent Brain (AdBrain) study, a neuroimaging study of adolescent twins; and the Siblings Interaction and Behavior Study (SIBS), a study of adoptive and nonadoptive families assessed from adolescence into young adulthood. Here we provide a brief overview of key features of these established studies and describe new MCTFR investigations that follow up and expand upon existing studies or recruit and assess new samples, including the MTR Study of Relationships, Personality, and Health (MTR-RPH); the Colorado-Minnesota (COMN) Marijuana Study; the Adolescent Brain Cognitive Development (ABCD) study; the Colorado Online Twins (CoTwins) study and the Children of Twins (CoT) study.
Weaning is known to induce important nutritional and energetic stress in piglets. Low-birthweight (LBW) piglets, now frequently observed in swine production, are more likely to be affected. The weaning period is also associated with dysfunctional immune responses, uncontrolled inflammation and oxidative stress conditions that are recognized risk factors for infections and diseases. Mounting evidence indicates that mitochondria, the main cellular sources of energy in the form of adenosine 5′ triphosphate (ATP) and primary sites of reactive oxygen species production, are related to immunity, inflammation and bacterial pathogenesis. However, no information is currently available regarding the link between mitochondrial energy production and oxidative stress in weaned piglets. The objective of this study was to characterize markers of cellular and mitochondrial energy metabolism and oxidative status in both normal-birthweight (NBW) and LBW piglets throughout the peri-weaning period. To conduct the study, 30 multiparous sows were inseminated and litters were standardized to 12 piglets. All the piglets were weighted at day 1 and 120 piglets were selected and assigned to 1 of 2 experimental groups: NBW (n = 60, mean weight of 1.73 ± 0.01 kg) and LBW piglets weighing less than 1.2 kg (n = 60, 1.01 ± 0.01 kg). Then, 10 piglets from each group were selected at 14, 21 (weaning), 23, 25, 29 and 35 days of age to collect plasma and organ (liver, intestine and kidney) samples. Analysis revealed that ATP concentrations were lower in liver of piglets after weaning than during lactation (P < 0.05) thus suggesting a significant impact of weaning stress on mitochondrial energy production. Oxidative damage to DNA (8-hydroxy-2′-deoxyguanosine, 8-OHdG) and proteins (carbonyls) measured in plasma increased after weaning and this coincides with a rise in enzymatic antioxidant activity of glutathione peroxidase (GPx) and superoxide dismutase (SOD) (P < 0.05). Mitochondrial activities of both GPx and SOD are also significantly higher (P < 0.05) in kidney of piglets after weaning. Additionally, oxidative damage to macromolecules is more important in LBW piglets as measured concentrations of 8-OHdG and protein carbonyls are significantly higher (P < 0.05) in plasma and liver samples, respectively, than for NBW piglets. These results provide novel information about the nature, intensity and duration of weaning stress by revealing that weaning induces mitochondrial dysfunction and cellular oxidative stress conditions which last for at least 2 weeks and more severely impact smaller piglets.
Apex predators play a critical role in maintaining the health of ecosystems but are highly susceptible to habitat degradation and loss caused by land-use changes, and to anthropogenic mortality. The leopard Panthera pardus is the last free-roaming large carnivore in the Western Cape province, South Africa. During 2011–2015, we carried out a camera-trap survey across three regions covering c. 30,000 km2 of the Western Cape. Our survey comprised 151 camera sites sampling nearly 14,000 camera-trap nights, resulting in the identification of 71 individuals. We used two spatially explicit capture–recapture methods (R programmes secr and SPACECAP) to provide a comprehensive density analysis capable of incorporating environmental and anthropogenic factors. Leopard density was estimated to be 0.35 and 1.18 leopards/100 km2, using secr and SPACECAP, respectively. Leopard population size was predicted to be 102–345 individuals for our three study regions. With these estimates and the predicted available leopard habitat for the province, we extrapolated that the Western Cape supports an estimated 175–588 individuals. Providing a comprehensive baseline population density estimate is critical to understanding population dynamics across a mixed landscape and helping to determine the most appropriate conservation actions. Spatially explicit capture–recapture methods are unbiased by edge effects and superior to traditional capture–mark–recapture methods when estimating animal densities. We therefore recommend further utilization of robust spatial methods as they continue to be advanced.
Stellarators are a promising route to steady-state fusion power. However, to achieve the required confinement, the magnetic geometry must be highly optimized. This optimization requires navigating high-dimensional spaces, often necessitating the use of gradient-based methods. The gradient of the neoclassical fluxes is expensive to compute with classical methods, requiring
flux computations, where
is the number of parameters. To reduce the cost of the gradient computation, we present an adjoint method for computing the derivatives of moments of the neoclassical distribution function for stellarator optimization. The linear adjoint method allows derivatives of quantities which depend on solutions of a linear system, such as moments of the distribution function, to be computed with respect to many parameters from the solution of only two linear systems. This reduces the cost of computing the gradient to the point that the finite-collisionality neoclassical fluxes can be used within an optimization loop. With the neoclassical adjoint method, we compute solutions of the drift kinetic equation and an adjoint drift kinetic equation to obtain derivatives of neoclassical quantities with respect to geometric parameters. When the number of parameters in the derivative is large (
), this adjoint method provides up to a factor of 200 reduction in cost. We demonstrate adjoint-based optimization of the field strength to obtain minimal bootstrap current on a surface. With adjoint-based derivatives, we also compute the local sensitivity to magnetic perturbations on a flux surface and identify regions where tight tolerances on error fields are required for control of the bootstrap current or radial transport. Furthermore, the solve for the ambipolar electric field is accelerated using a Newton method with derivatives obtained from the adjoint method.
Nursing piglets are entirely dependent, for their micronutrient provisions, upon in utero, colostrum and milk transfers from the dam. An adequate maternal transfer of micronutrients is all the more important during these periods which, in fact, lasts for approximately half the life cycle (conception to slaughter) of modern pigs. The present study aimed to set up a simple approach to assess the maternal perinatal transfer of vitamins and trace elements in sows. Prenatal transfer (R-u) was estimated as limited, passive or active using the ratio between pre-colostral serum concentrations of a given micronutrient in newborn piglets and corresponding pre-farrowing values in sows. Efficiency of the postnatal transfer (R-c) was estimated from the ratio between serum concentrations of post- and pre-colostral micronutrients in piglets. Data from literature (12 studies) were used for vitamins A, D, E, C, folic acid and B12, whereas vitamins B2, B3, B6 and B8 as well as Zn, Fe, Cu and Se were generated from a trial where blood sera from 20 sows, and their litter were collected during the perinatal period. In sow trial, statistical t tests were used to determine if ratios differed from 1. Prenatal transfer was active and in favour of piglets (R-u > 1, P < 0.03) for Zn and vitamins B6 and B8 (sow trial) as well as for vitamins C and B12 (literature data). This transfer was limited (R-u < 1, P < 0.01) for vitamin B2, Fe, Cu and Se (sow trial) and for vitamins A, E, D and folic acid (literature data) whereas it was passive for vitamin B3 (R-u = 1, P > 0.37). After birth, the early postnatal transfer through colostrum was active towards piglets for most micronutrients but vitamins B6 and B8 (R-c < 1, P < 0.01). Globally, the perinatal transfer (combination of R-u and R-c) was favourable to the neonatal piglets for most micronutrients except for vitamins A and D as well as Fe, Cu and Se whereas there is apparently a barrier for prenatal transfer which is not compensated by the colostrum provision to neonatal piglets. Then, post-colostral concentrations of these micronutrients in piglets remain below prenatal levels of their dam. Neonatal strategies of micronutrient provision are known for Fe (intramuscular injection) and Se (sow milk enrichment). Further studies are needed to assess the importance of the unfavourable perinatal transfer for Cu and vitamins A and D for piglet robustness later in life.
The Beck’s Petrel Pseudobulweria beckii is a ‘Critically Endangered’ seabird whose breeding sites remain unknown. Historic observations suggest the species’ distribution is concentrated in the Bismarck Archipelago and particularly southern New Ireland. Over the course of two research expeditions in 2016 and 2017 we used on-land and at-sea observations, local interviews and satellite telemetry to understand the distribution of the species, its at-sea movements and potential breeding locations. Land-based and at-sea observations indicated that the area of Silur Bay in southern New Ireland was a significant site for Beck’s Petrel with numbers of birds increasing near shore prior to dusk and birds observed in spotlights over land. A local population is estimated to be in the low thousands. In 2017 a single Beck’s was captured at sea, fitted with a satellite transmitter and tracked for eight months. This bird maintained a core distribution off the south-east coast of New Ireland and north of Bougainville for 122 days. During the tracking period, the bird was located over land at night seven times; predominantly over southern New Ireland, where the signal was also lost for extended periods suggesting occupancy of an underground burrow. In August the bird migrated 1,400 km to a core pelagic habitat north of West Papua before the signal was eventually lost. Our combination of land- and sea-based observations and analysis of behaviour from satellite tracking supports the conclusion that a breeding site for Beck’s Petrel lies in the inland mountains of southern New Ireland and most likely in the high-altitude zone (> 2000 m) of the Hans Meyer Range. Further investigations are required to determine the exact location of breeding colonies in the mountains of southern New Ireland and the importance of a potential west Papuan non-breeding pelagic habitat for the species.
The shape gradient quantifies the change in some figure of merit resulting from differential perturbations to a shape. Shape gradients can be applied to gradient-based optimization, sensitivity analysis and tolerance calculation. An efficient method for computing the shape gradient for toroidal three-dimensional magnetohydrodynamic (MHD) equilibria is presented. The method is based on the self-adjoint property of the equations for driven perturbations of MHD equilibria and is similar to the Onsager symmetry of transport coefficients. Two versions of the shape gradient are considered. One describes the change in a figure of merit due to an arbitrary displacement of the outer flux surface; the other describes the change in the figure of merit due to the displacement of a coil. The method is implemented for several example figures of merit and compared with direct calculation of the shape gradient. In these examples the adjoint method reduces the number of equilibrium computations by factors of
is the number of parameters used to describe the outer flux surface or coil shapes.
Breakthrough Listen is a 10-yr initiative to search for signatures of technologies created by extraterrestrial civilisations at radio and optical wavelengths. Here, we detail the digital data recording system deployed for Breakthrough Listen observations at the 64-m aperture CSIRO Parkes Telescope in New South Wales, Australia. The recording system currently implements two modes: a dual-polarisation, 1.125-GHz bandwidth mode for single-beam observations, and a 26-input, 308-MHz bandwidth mode for the 21-cm multibeam receiver. The system is also designed to support a 3-GHz single-beam mode for the forthcoming Parkes ultra-wideband feed. In this paper, we present details of the system architecture, provide an overview of hardware and software, and present initial performance results.
Previous research has shown that problematic parent–child, peer, and romantic partner relationships are associated with an increased likelihood for major depressive disorder (MDD). Less research has evaluated the developmental unfolding of how these interpersonal relationship features are both an antecedent versus a consequence of MDD symptoms from adolescence through young adulthood. These gaps were evaluated using a large community sample (N = 1,127; 54% female, 96% white) via a developmental cascade model. Results showed support for significant antecedent effects, as greater parent–child relationship problems at ages 11 and 17 predicted rank-order increases in MDD symptoms at ages 14 and 20. Supporting a developmental cascade of problematic social relationships, greater parent–child relationship problems at ages 11 and 14 also predicted greater subsequent rank-order increases in antisocial peer affiliation at ages 14 and 17. Greater affiliation to antisocial peers at age 20 predicted greater rank-order increases in romantic relationship problems at age 24, which in turn predicted greater MDD symptoms at age 29. Cross-effects were generally small (βs ≤ .16), illustrating other factors may be relevant to the development or consequences of MDD. Nonetheless, findings support the importance of efforts to strengthen social support networks to offset risk as well as potentially treat depression.
The Cambridge Handbook of Violent Behavior and Aggression presents the current state of knowledge related to the study of violent behaviors and aggression. An important extension of the first Handbook published ten years ago, the second edition maintains a distinctly cross-disciplinary focus by representing the newest scholarship and insights from behavior genetics, cross-cultural comparative psychology/criminology, evolutionary psychology, criminal justice, criminology, human development, molecular genetics, neurosciences, psychology, prevention and intervention sciences, psychiatry, psychopharmacology, public health, and sociology. The Handbook is divided into introductory and overview chapters on the study of violent behavior and aggression, followed by chapters on biosocial bases, individual and interpersonal factors, contextual factors, and prevention and intervention work and policy implications. It is an essential resource for researchers, scholars, and graduate students across social and behavioral science disciplines interested in the etiology, intervention, and prevention of violent behavior and aggression.