Light curves and colours of the ejecta from Dimorphos after the DART impact

On 26 September 2022, the Double Asteroid Redirection Test (DART) spacecraft struck Dimorphos, a satellite of the asteroid 65803 Didymos1. Because it is a binary system, it is possible to determine how much the orbit of the satellite changed, as part of a test of what is necessary to deflect an asteroid that might threaten Earth with an impact. In nominal cases, pre-impact predictions of the orbital period reduction ranged from roughly 8.8 to 17 min (refs. 2,3). Here we report optical observations of Dimorphos before, during and after the impact, from a network of citizen scientists' telescopes across the world. We find a maximum brightening of 2.29 ± 0.14 mag on impact. Didymos fades back to its pre-impact brightness over the course of 23.7 ± 0.7 days. We estimate lower limits on the mass contained in the ejecta, which was 0.3-0.5% Dimorphos's mass depending on the dust size. We also observe a reddening of the ejecta on impact.

Weight change following US military service

BACKGROUND

Although overweight and obesity are less prevalent among active-duty military personnel compared with similar persons not serving in the military, no such differences have been observed between veterans and non-veterans.

OBJECTIVES

To assess the magnitude of weight changes before, concurrent with and following discharge from the military, relative to weight during service, and to determine the demographic, service-related and psychological characteristics associated with clinically important weight gain among those who were discharged from military service during follow-up.

METHODS

Eligible Millennium Cohort Study participants (n=38 686) completed the questionnaires approximately every 3 years (2001, 2004 and 2007) that were used to estimate annual weight changes, as well as the percentage experiencing clinically important weight gain, defined as 10%. Analyses were stratified by sex.

RESULTS

Weight gain was greatest around the time of discharge from service and in the 3 years before discharge (1.0-1.3 kg per year), while it was nearly half as much during service (0.6-0.7 kg per year) and 3 years after service ended (0.7 kg per year). Consequently, 6-year weight gain was over 2 kg greater in those who were discharged compared with those who remained in the military during follow-up (5.7 vs 3.5 kg in men; 6.3 vs 4.0 kg in women). In those who were discharged, younger age, less education, being overweight at baseline, being in the active-duty component (vs Reserve/National Guard) and having experienced deployment with combat exposures (vs non-deployment) were associated with increased risks of clinically important weight gain.

CONCLUSIONS

This study provides the first prospectively collected evidence for an increased rate of weight gain around the time of military discharge that may explain previously reported higher rates of obesity in veterans, and identifies characteristics of higher-risk groups. Discharge from military service presents a window of risk and opportunity to prevent unhealthy weight gain in military personnel and veterans.

Genetic testing: can it predict the lived experience of individuals and families? A personal testimony

An individual's and family's experience with a genetic disease is too complex and diverse to be totally predicted using genetic testing. Stigmatization and discrimination of gene carriers can occur if society chooses to utilize genetic technology to eliminate 'disease and disability' without accepting human variation and devoting any possible efforts for ameliorating the life of individuals faced with disabilities. In this paper I use Friedreich's ataxia (FA) to illustrate some ways in which a disease experience can differ from what is expected from textbook descriptions of a given condition. I describe the expected medical characteristics with FA and some of my own personal experience with the disease as well as that of my family.

Geographic variation in patient surveillance after radical prostatectomy

BACKGROUND

Prostate cancer is often diagnosed early enough in its clinical course to permit radical prostatectomy to be done with curative intent, yet many patients experience tumor recurrence. Most patients receive postoperative surveillance, but the intensity of testing varies appreciably. We sought to evaluate the influence of geographic location on the variability of surveillance intensity.

METHODS

Questionnaires pertaining to postoperative surveillance were mailed to 4467 members of the American Urological Association (AUA). Practice pattern variation was assessed among 24 large metropolitan statistical areas, among nine United States census regions, and by health maintenance organization penetration rate.

RESULTS

Of 4467 urologists surveyed, 1416 (32%) responded and 1050 (24%) responses were evaluable. Correlation analysis showed that mean follow-up intensity across modalities surveyed was highly correlated across tumor, node, metastasis (TNM) stages and years postsurgery. We found no significant main effects attributable to metropolitan statistical area, United States (US) census region, or health maintenance organization (HMO) penetration rate for commonly used surveillance modalities: serum prostate-specific antigen (PSA), office visit, and urinalysis. For infrequently used modalities, there were minimal effects on testing intensity of US census region, metropolitan statistical area, and HMO penetration rate. Few two-way and three-way interactions were significant.

CONCLUSIONS

The utilization of commonly used surveillance modalities by urologists caring for patients after radical prostatectomy is not affected by metropolitan statistical area, US census region, or HMO penetration rate.

The genetics of Alzheimer disease and the application of molecular tests

Two general classes of genes are associated with the development of Alzheimer disease (AD). The first group consists of genes that appear to cause AD when mutated, and the second category is composed of genes that are statistically associated with AD, depending on the inheritance of specific alleles. This paper reviews the current state of knowledge about the genetics of AD, and we then discuss the two molecular tests that are currently commercially available. These include a genetic test for mutations in the presenilin 1 (PS1) gene that can diagnose or predict a subset of early onset familial AD with a high degree of certainty. The value of the genetic test for the apolipoprotein (APOE) allele status is far less clear. Inheritance of the epsilon 4 allele is associated with an increased risk of AD at a population level, but APOE genotyping is inappropriate for prediction of future disease in an individual and offers only a marginal increase in diagnostic certainty when symptomatic individuals are tested. In the future, genetic tests may become more broadly applicable to the diagnosis and prediction of AD. However, the utility of such tests is currently limited to a small subset of individuals because in the vast majority of AD cases no clear genetic or environmental cause has been defined.

Spatial Scales of Current Speed and Phytoplankton Biomass Fluctuations in Lake Tahoe

Spectral analysis of current speed and chlorophyll a measurements in Lake Tahoe, California and Nevada, indicates that considerably more variance exists at longer length scales in chlorophyll than in the current speeds. Increasingly, above scales of approximately 100 meters, chlorophyll does not behave as a simple passive contaminant distributed by turbulence, which indicates that biological processes contribute significantly to the observed variance at these large length scales.