The Gravity Recovery and Climate Experiment space gravity mission provides one of the principal means of estimating present‐day mass loss occurring in polar regions. Extraction of the mass loss ...signal from the observed gravity changes is complicated by the need to first remove the signal of ongoing glacial isostatic adjustment (GIA) since the Last Glacial Maximum. This can be problematic in regions such as Antarctica where the GIA models are poorly constrained by observation and their accuracy is not well known. We present a new methodology that permits the GIA component to be represented mathematically by a simple, linear expression of the ratio of viscoelastic Love numbers that is valid for a broad range of Earth and ice‐load models. The expression is shown to reproduce rigorous computations of surface uplift rates to within 0.3 mm/yr, thus providing a means of inverting simultaneously for present‐day mass loss and ongoing GIA with all the accuracy of a fully detailed forward model.
Key Points
Ratio of deformational & gravitational Love numbers is independent of ice model
Ratio of deformational & gravitational Love numbers is independent of rheology
Numerically‐derived ratio values offer greater accuracy than earlier theory
Reinforcement learning theory distinguishes “model-free” learning, which fosters reflexive repetition of previously rewarded actions, from “model-based” learning, which recruits a mental model of the ...environment to flexibly select goal-directed actions. Whereas model-free learning is evident across development, recruitment of model-based learning appears to increase with age. However, the cognitive processes underlying the development of model-based learning remain poorly characterized. Here, we examined whether age-related differences in cognitive processes underlying the construction and flexible recruitment of mental models predict developmental increases in model-based choice. In a cohort of participants aged 9–25, we examined whether the abilities to infer sequential regularities in the environment (“statistical learning”), maintain information in an active state (“working memory”) and integrate distant concepts to solve problems (“fluid reasoning”) predicted age-related improvements in model-based choice. We found that age-related improvements in statistical learning performance did not mediate the relationship between age and model-based choice. Ceiling performance on our working memory assay prevented examination of its contribution to model-based learning. However, age-related improvements in fluid reasoning statistically mediated the developmental increase in the recruitment of a model-based strategy. These findings suggest that gradual development of fluid reasoning may be a critical component process underlying the emergence of model-based learning.
Objective.—To evaluate the efficacy of topiramate in the preventative treatment of episodic migraine.
Background.—Topiramate is a broad‐spectrum antiepileptic drug effective for treatment of multiple ...seizure types in adults and children. Antiepileptic agents have demonstrated efficacy in migraine prevention, and open‐label experience from our clinic has suggested that topiramate might be effective for this use. We consequently conducted a single‐center, double‐blind, placebo‐controlled trial to evaluate the efficacy and safety of topiramate for the preventative treatment of migraine.
Methods.—Forty patients, aged 19 to 62 years (mean, 38.2 years), were randomly assigned in a 1:1 ratio to receive topiramate (n = 19; all women) or placebo (n = 21; 20 women, 1 man). Following a prospective baseline phase of 4 weeks, the study drug dose was titrated weekly in 25‐mg increments over 8 weeks to 200 mg per day or to the maximum tolerated dose. The titration phase was followed by an 8‐week maintenance phase.
Results.—During the entire double‐blind phase, topiramate‐treated patients experienced a significantly lower 28‐day migraine frequency (3.31 ± 1.7 versus 3.83 ± 2.1; P = .002) compared to placebo, irrespective of use of concomitant migraine prevention medications. The mean 28‐day migraine frequency was reduced by 36% in patients receiving topiramate as compared with 14% in patients receiving placebo (P = .004). Twenty‐six percent of the patients on topiramate and 9.5% of the patients on placebo achieved a 50% reduction in migraine frequency (P > .05). The mean dose of topiramate was 125 mg per day (range, 25 to 200 mg per day). Topiramate was well tolerated; 2 of 19 topiramate‐treated patients discontinued treatment due to adverse events. Adverse effects that occurred more frequently in topiramate‐treated patients included paresthesia, weight loss, altered taste, anorexia, and memory impairment.
Conclusions.—Preventative therapy with topiramate significantly reduced migraine frequency. Larger multicenter clinical studies may further delineate the role of topiramate in migraine prevention.
Maternal diet-induced obesity can cause detrimental developmental origins of health and disease in offspring. Perinatal exposure to a high-fat diet (HFD) can lead to later behavioral and metabolic ...disturbances, but it is not clear which behaviors and metabolic parameters are most vulnerable. To address this critical gap, biparental and monogamous oldfield mice (Peromyscus polionotus), which may better replicate most human societies, were used in the current study. About 2 weeks before breeding, adult females were placed on a control or HFD and maintained on the diets throughout gestation and lactation. F1 offspring were placed at weaning (30 days of age) on the control diet and spatial learning and memory, anxiety, exploratory, voluntary physical activity, and metabolic parameters were tested when they reached adulthood (90 days of age). Surprisingly, maternal HFD caused decreased latency in initial and reverse Barnes maze trials in male, but not female, offspring. Both male and female HFD-fed offspring showed increased anxiogenic behaviors, but decreased exploratory and voluntary physical activity. Moreover, HFD offspring demonstrated lower resting energy expenditure (EE) compared with controls. Accordingly, HFD offspring weighed more at adulthood than those from control fed dams, likely the result of reduced physical activity and EE. Current findings indicate a maternal HFD may increase obesity susceptibility in offspring due to prenatal programming resulting in reduced physical activity and EE later in life. Further work is needed to determine the underpinning neural and metabolic mechanisms by which a maternal HFD adversely affects neurobehavioral and metabolic pathways in offspring.
Context
. The calibration of optical polarimeters relies on the use of stars with negligible polarization (i.e., unpolarized standard stars) for determining the instrumental polarization zero point. ...For wide-field polarimeters, calibration is often done by imaging the same star over multiple positions in the field of view (FoV), which is a time-consuming process. A more effective technique is to target fields containing multiple standard stars. While this method has been used for fields with highly polarized stars, there are no such sky regions with well measured unpolarized standard stars.
Aims
. We aim to identify sky regions with tens of stars exhibiting negligible polarization that are suitable for a zero-point calibration of wide-field polarimeters.
Methods
. We selected stars in regions with extremely low reddening, located at high Galactic latitudes. We targeted four ~40′ × 40′ fields in the northern and eight in the southern equatorial hemispheres. Observations were carried out at the Skinakas Observatory and the South African Astronomical Observatory.
Results
. We found two fields in the north and seven in the south characterized by a mean polarization lower than
p <
0.1%.
Conclusions
. At least 9 out of the 12 fields can be used for a zero-point calibration of wide-field polarimeters.
Background: Low bone mineral density (BMD) is recognised in individuals with cystic fibrosis (CF) although the pathogenesis remains unclear. The aims of this study were to compare BMD over a broad ...continuum of Australian individuals with CF with healthy controls and to examine the relationship between BMD and clinical parameters including physical activity, nutrition, and vitamin D levels. Methods: BMD of the lumbar spine (LS), total body (TB), femoral neck (FN), cortical wrist (R33%), and distal wrist (RUD) was examined in 153 individuals with CF aged 5.3–55.8 years (84 males) and in 149 local controls aged 5.6–48.3 years (66 males) using dual energy x ray absorptiometry. Anthropometric variables, body cell mass, markers of disease severity, corticosteroid usage, measures of physical activity, dietary calcium and caloric intake and serum vitamin D were assessed and related to BMD. Results: Compared with controls, mean BMD was not significantly different in children aged 5–10 years with CF. Adolescents (females 11–18 years, males 11–20 years) had reduced TB and R33% BMD when adjusted for age, sex, and height (difference in BMD (g/cm2) adjusted means between control and CF: TB = 0.04 (95% CI 0.01 to 0.07); R33% = 0.03 (95% CI 0.01 to 0.06)). BMD was reduced at all sites except R33% in adults (difference in BMD (g/cm2) adjusted means between control and CF: TB = 0.05 (95% CI 0.02 to 0.09); LS = 0.08 (95% CI 0.03 to 0.14); FN = 0.09 (95% CI 0.03 to 0.15); RUD = 0.03 (95% CI 0.01 to 0.05)). In children/adolescents BMD was weakly associated with nutritional status and disease severity. Conclusions: BMD was normal in a well nourished group of prepubertal children with CF. A BMD deficit appears to evolve during adolescence and becomes more marked in adults. Individuals with CF should optimise nutrition, partake in physical activity, and maximise lung health in order to optimise BMD. Further longitudinal studies are required to understand the evolution of reduced BMD in young people and adults with CF.
Data on the fish fauna of the Leschenault Estuary on the lower west coast of Australia were collected and used as a model to elucidate the characteristics of permanently open estuaries with a reverse ...salinity gradient, which undergo seasonal changes similar to many other estuaries with Mediterranean climate. Focus was placed on determining (1) the relationships of the number of species, density, life cycle category and species composition of fishes with region (within estuary), season and year and salinity, (2) whether species are partitioned along the lengths of such systems and (3) the extent and significance of any inter‐decadal changes in species composition. The analyses and interpretation involved using multi‐factorial permutational multivariate analysis of variance (PERMANOVA) and analysis of similarity (ANOSIM) designs, and three new or recently published visualization tools, i.e. modified non‐metric multidimensional scaling (nMDS) plots, coherent species curves and segmented bubble plots. The base, lower, upper and apex regions of the Leschenault Estuary, along which the salinity increased in each season except in winter when most rainfall occurs, were sampled seasonally for the 2 years between winter 2008 and autumn 2010. Estuarine residents contributed twice as many individuals, but less than half the number of species as marine taxa. While the numbers of marine species and estuarine residents declined between the base or lower and apex regions, the individuals of marine species dominated the catches in the base region and estuarine residents in the other three regions. Ichthyofaunal composition in each region underwent conspicuous annual cyclical changes, due to time‐staggered differences in recruitment among species, and changed sequentially along the estuary, both paralleling salinity trends. Different groups of species characterized the fauna in the different regions and seasons, thereby partitioning resources among species. The ichthyofauna of the apex region, in which salinities reached 54 and temperatures 36° C, recorded the highest maximum density and, in terms of abundance, was dominated (90%) by three atherinid species, emphasizing the ability of this family to tolerate extreme conditions. Comparisons between the data for 2008–2010 and 1994 demonstrate that the spotted hardyhead Craterocephalus mugiloides and the common hardyhead Atherinomorus vaigiensis had colonized and become abundant in the Leschenault Estuary in the intervening period. This represents a southwards extension of the distribution of these essentially tropical species during a period of increasing coastal water temperatures as a result of climate change. The abundance of weed‐associated species, e.g. the western gobbleguts Ostorhinchus rueppellii and the soldier Gymnapistes marmoratus, increased, whereas that of the longfinned goby Favonigobius lateralis decreased, probably reflecting increases in eutrophication and siltation, respectively.
Summary
We report on a genomic and functional analysis of a novel marine siphovirus, the Vibrio phage SIO‐2. This phage is lytic for related Vibrio species of great ecological interest including the ...broadly antagonistic bacterium Vibrio sp. SWAT3 as well as notable members of the Harveyi clade (V. harveyi ATTC BAA‐1116 and V. campbellii ATCC 25920). Vibrio phage SIO‐2 has a circularly permuted genome of 80 598 bp, which displays unusual features. This genome is larger than that of most known siphoviruses and only 38 of the 116 predicted proteins had homologues in databases. Another divergence is manifest by the origin of core genes, most of which share robust similarities with unrelated viruses and bacteria spanning a wide range of phyla. These core genes are arranged in the same order as in most bacteriophages but they are unusually interspaced at two places with insertions of DNA comprising a high density of uncharacterized genes. The acquisition of these DNA inserts is associated with morphological variation of SIO‐2 capsid, which assembles as a large (80 nm) shell with a novel T = 12 symmetry. These atypical structural features confer on SIO‐2 a remarkable stability to a variety of physical, chemical and environmental factors. Given this high level of functional and genomic novelty, SIO‐2 emerges as a model of considerable interest in ecological and evolutionary studies.
The new generation of direct electron detectors has been a major contributor to the recent resolution revolution in cryo-electron microscopy. Optimal use of these new cameras using automated data ...collection software is critical for high-throughput near-atomic resolution cryo-electron microscopy research. We present an overview of the practical aspects of automated data collection in the context of this new generation of direct detectors, highlighting the differences, challenges, and opportunities the new detectors provide compared to the previous generation of data acquisition media.
Objective To evaluate the association between body mass index and mortality from overall cardiovascular disease and specific subtypes of cardiovascular disease in east and south Asians.Design Pooled ...analyses of 20 prospective cohorts in Asia, including data from 835 082 east Asians and 289 815 south Asians. Cohorts were identified through a systematic search of the literature in early 2008, followed by a survey that was sent to each cohort to assess data availability.Setting General populations in east Asia (China, Taiwan, Singapore, Japan, and Korea) and south Asia (India and Bangladesh).Participants 1 124 897 men and women (mean age 53.4 years at baseline).Main outcome measures Risk of death from overall cardiovascular disease, coronary heart disease, stroke, and (in east Asians only) stroke subtypes.Results 49 184 cardiovascular deaths (40 791 in east Asians and 8393 in south Asians) were identified during a mean follow-up of 9.7 years. East Asians with a body mass index of 25 or above had a raised risk of death from overall cardiovascular disease, compared with the reference range of body mass index (values 22.5-24.9; hazard ratio 1.09 (95% confidence interval 1.03 to 1.15), 1.27 (1.20 to 1.35), 1.59 (1.43 to 1.76), 1.74 (1.47 to 2.06), and 1.97 (1.44 to 2.71) for body mass index ranges 25.0-27.4, 27.5-29.9, 30.0-32.4, 32.5-34.9, and 35.0-50.0, respectively). This association was similar for risk of death from coronary heart disease and ischaemic stroke; for haemorrhagic stroke, the risk of death was higher at body mass index values of 27.5 and above. Elevated risk of death from cardiovascular disease was also observed at lower categories of body mass index (hazard ratio 1.19 (95% confidence interval 1.02 to 1.39) and 2.16 (1.37 to 3.40) for body mass index ranges 15.0-17.4 and <15.0, respectively), compared with the reference range. In south Asians, the association between body mass index and mortality from cardiovascular disease was less pronounced than that in east Asians. South Asians had an increased risk of death observed for coronary heart disease only in individuals with a body mass index greater than 35 (hazard ratio 1.90, 95% confidence interval 1.15 to 3.12).Conclusions Body mass index shows a U shaped association with death from overall cardiovascular disease among east Asians: increased risk of death from cardiovascular disease is observed at lower and higher ranges of body mass index. A high body mass index is a risk factor for mortality from overall cardiovascular disease and for specific diseases, including coronary heart disease, ischaemic stroke, and haemorrhagic stroke in east Asians. Higher body mass index is a weak risk factor for mortality from cardiovascular disease in south Asians.
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