Root system size and root hair length are key phenes for nitrate acquisition and biomass production across natural variation in Arabidopsis.

The role of root phenes in nitrogen (N) acquisition and biomass production was evaluated in 10 contrasting natural accessions of Arabidopsis thaliana L. Seedlings were grown on vertical agar plates with two different nitrate supplies. The low N treatment increased the root to shoot biomass ratio and promoted the proliferation of lateral roots and root hairs. The cost of a larger root system did not impact shoot biomass. Greater biomass production could be achieved through increased root length or through specific root hair characteristics. A greater number of root hairs may provide a low-resistance pathway under elevated N conditions, while root hair length may enhance root zone exploration under low N conditions. The variability of N uptake and the expression levels of genes encoding nitrate transporters were measured. A positive correlation was found between root system size and high-affinity nitrate uptake, emphasizing the benefits of an exploratory root organ in N acquisition. The expression levels of NRT1.2/NPF4.6, NRT2.2, and NRT1.5/NPF7.3 negatively correlated with some root morphological traits. Such basic knowledge in Arabidopsis demonstrates the importance of root phenes to improve N acquisition and paves the way to design eudicot ideotypes.

Diverse predictors of early attrition in an elite Marine training school.

Reconnaissance Marine training is deliberately difficult, to assure that graduates have the capabilities required to function successfully in the high-risk military occupational specialty. The majority of training attrition is due to voluntary withdrawal and previous research has identified certain predictive factors such as demographics, mental status, and physical performance. While some characteristics of training attrition have been identified, there is still a lack of understanding related to an individual's profile that is more apt to complete Recon training. Retrospective survey data was analyzed from 3,438 trainees within the Reconnaissance Training Company. Surveys were related to trainees' military recruitment history and other military experience, prior life experience, athletic experience, self-identified personality characteristics and motivations, and reasons for voluntary withdrawal if applicable, as well as physical performance metrics. Various demographic factors, self-reported hobbies, motivations, aquatic experience, and physical performance were associated with success in Recon Marine training courses. Subjects who voluntarily withdrew from training most commonly cited mental stress and aquatic rigor as the reason and less commonly cited reasons were physical and family reasons. These results could potentially increase training success, but more research is needed to understand the relationships between the observed trainee characteristics and success in elite warfighter training.

A review of sleep-promoting medications used in pregnancy.

Approximately 4% of adults who have symptoms of insomnia resort to various hypnotic or sedating medications for acute symptom relief. Although typically a common practice for nonpregnant adults, this is not the case for the thousands of pregnant women who also report substantial sleep issues. Unfortunately, a paucity of randomized controlled trials in this population, scant empiric evidence regarding the appropriateness of prescribing options, and the concern of subsequent teratogenicity restricts the ability of clinicians to make informed decisions. We synthesized the current research regarding hypnotics and sedating medications used (both on- and off-label) during pregnancy and their association with adverse outcomes. Medications that we investigated included benzodiazepines, hypnotic benzodiazepine receptor agonists, antidepressants, and antihistamines. Overall, the examined studies showed no correlation of increased risk of congenital malformations. However, benzodiazepines and hypnotic benzodiazepine receptor agonists may increase rates of preterm birth, low birthweight, and/or small-for-gestational-age infants. The small number of studies and the small number of subjects prohibit any definitive interpretation regarding the consequences of the use of hypnotic or sedating medications in pregnancy. Additional case reports, randomized clinical trials, and epidemiologic studies are needed urgently.

Continuous Measurement of Reconnaissance Marines in Training With Custom Smartphone App and Watch: Observational Cohort Study.

BACKGROUND: Specialized training for elite US military units is associated with high attrition due to intense psychological and physical demands. The need to graduate more service members without degrading performance standards necessitates the identification of factors to predict success or failure in targeted training interventions. OBJECTIVE: The aim of this study was to continuously quantify the mental and physical status of trainees of an elite military unit to identify novel predictors of success in training. METHODS: A total of 3 consecutive classes of a specialized training course were provided with an Apple iPhone, Watch, and specially designed mobile app. Baseline personality assessments and continuous daily measures of mental status, physical pain, heart rate, activity, sleep, hydration, and nutrition were collected from the app and Watch data. RESULTS: A total of 115 trainees enrolled and completed the study (100% male; age: mean 22 years, SD 4 years) and 64 (55.7%) successfully graduated. Most training withdrawals (27/115, 23.5%) occurred by day 7 (mean 5.5 days, SD 3.4 days; range 1-22 days). Extraversion, positive affect personality traits, and daily psychological profiles were associated with course completion; key psychological factors could predict withdrawals 1-2 days in advance (P=.009). CONCLUSIONS: Gathering accurate and continuous mental and physical status data during elite military training is possible with early predictors of withdrawal providing an opportunity for intervention.

Consumer-facing Diagnostic Sensors in a Patient with Implantable Cardioverter-Defibrillator.

Since its introduction in 2015, the Apple Watch (Apple Inc., Cupertino, CA, USA) has been purchased by an estimated 60 million consumers and boasts algorithms cleared by the United States Food and Drug Administration able to detect bradycardia, tachycardia, and atrial fibrillation, with the newest version of the device also allowing for real-time electrocardiogram acquisition. This case offers potentially the first demonstration of an Apple Watch correctly detecting atrial fibrillation with an implantable cardioverter-defibrillator confirming the accuracy of the detection from stored electrograms.

Minimal Effect of Daytime Napping Behavior on Nocturnal Sleep in Pregnant Women.

STUDY OBJECTIVES: To assess whether daytime naps negatively impact nocturnal sleep. DESIGN: Longitudinal, prospective cohort design. PARTICIPANTS: 161 pregnant women recruited and evaluated in early gestation (10-20 weeks). MEASUREMENTS AND RESULTS: Daily sleep information was collected in three 2-week periods (10-12, 14-16, and 18-20 weeks gestation) with a daily sleep diary and an actigraph. The average number of naps, as well as the average length of each nap, were calculated from sleep diaries. Women were categorized first as non nappers (0 naps/2-week period), moderate nappers (1-3 naps/2-week period), or frequent nappers (≥ 4 naps/2-week period). Then, based on the average nap length, they were categorized as short (< 90 min) or long (≥ 90 min) nappers. Nocturnal sleep parameters included SOL, WASO, SE, and TST. SAS procedure MIXED was used for modeling the main effects of nap group and time, and time by nap group interactions. Women who took naps had a decrease in diary-assessed nocturnal TST, but not actigraphy-assessed TST. This observation was group- and time-specific. There were no other group differences. Women who napped ≥ 90 min had poorer diary-assessed SE and lower diary-assessed TST than those who took shorter naps. Length of nap was not associated with any other sleep measures. CONCLUSIONS: The number of daytime naps have minimal impact on nocturnal sleep parameters; however, long nappers did exhibit modestly impaired sleep continuity and sleep quality. Overall, we propose that daytime naps provide a beneficial countermeasure to the sleep disruption commonly reported by pregnant women. This may be clinically beneficial given that sleep continuity and quality are important correlates of pregnancy outcomes. COMMENTARY: A commentary on this article appears in this issue on page 593.