SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: The Onset

178

Under high-strain-rate compression (strain rate approximately 10(3) s(-1)), nacre (mother-of-pearl) exhibits surprisingly high fracture strength vis-à-vis under quasi-static loading (strain rate 10(-3) s(-1)). Nevertheless, the underlying mechanism responsible for such sharply different behaviors in these two loading modes remains completely unknown. Here we report a new deformation mechanism, adopted by nacre, the best-ever natural armor material, to protect itself against predatory penetrating impacts. It involves the emission of partial dislocations and the onset of deformation twinning that operate in a well-concerted manner to contribute to the increased high-strain-rate fracture strength of nacre. Our findings unveil that Mother Nature delicately uses an ingenious strain-rate-dependent stiffening mechanism with a purpose to fight against foreign attacks. These findings should serve as critical design guidelines for developing engineered body armor materials.

Concepts: Materials science, Nature, Young's modulus, Solid mechanics, The Onset, Nacre, Aragonite, Deformation

175

Background Zika virus (ZIKV) infection has been linked to the Guillain-Barré syndrome. From November 2015 through March 2016, clusters of cases of the Guillain-Barré syndrome were observed during the outbreak of ZIKV infection in Colombia. We characterized the clinical features of cases of Guillain-Barré syndrome in the context of this ZIKV infection outbreak and investigated their relationship with ZIKV infection. Methods A total of 68 patients with the Guillain-Barré syndrome at six Colombian hospitals were evaluated clinically, and virologic studies were completed for 42 of the patients. We performed reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assays for ZIKV in blood, cerebrospinal fluid, and urine, as well as antiflavivirus antibody assays. Results A total of 66 patients (97%) had symptoms compatible with ZIKV infection before the onset of the Guillain-Barré syndrome. The median period between the onset of symptoms of ZIKV infection and symptoms of the Guillain-Barré syndrome was 7 days (interquartile range, 3 to 10). Among the 68 patients with the Guillain-Barré syndrome, 50% were found to have bilateral facial paralysis on examination. Among 46 patients in whom nerve-conduction studies and electromyography were performed, the results in 36 patients (78%) were consistent with the acute inflammatory demyelinating polyneuropathy subtype of the Guillain-Barré syndrome. Among the 42 patients who had samples tested for ZIKV by RT-PCR, the results were positive in 17 patients (40%). Most of the positive RT-PCR results were in urine samples (in 16 of the 17 patients with positive RT-PCR results), although 3 samples of cerebrospinal fluid were also positive. In 18 of 42 patients (43%) with the Guillain-Barré syndrome who underwent laboratory testing, the presence of ZIKV infection was supported by clinical and immunologic findings. In 20 of these 42 patients (48%), the Guillain-Barré syndrome had a parainfectious onset. All patients tested were negative for dengue virus infection as assessed by RT-PCR. Conclusions The evidence of ZIKV infection documented by RT-PCR among patients with the Guillain-Barré syndrome during the outbreak of ZIKV infection in Colombia lends support to the role of the infection in the development of the Guillain-Barré syndrome. (Funded by the Bart McLean Fund for Neuroimmunology Research and others.).

Concepts: Immune system, Cerebrospinal fluid, Fever, Dengue fever, The Onset, Chronic inflammatory demyelinating polyneuropathy, 2016, 2015

59

The ages of puberty, first sexual intercourse and first birth signify the onset of reproductive ability, behavior and success, respectively. In a genome-wide association study of 125,667 UK Biobank participants, we identify 38 loci associated (P < 5 × 10(-8)) with age at first sexual intercourse. These findings were taken forward in 241,910 men and women from Iceland and 20,187 women from the Women's Genome Health Study. Several of the identified loci also exhibit associations (P < 5 × 10(-8)) with other reproductive and behavioral traits, including age at first birth (variants in or near ESR1 and RBM6-SEMA3F), number of children (CADM2 and ESR1), irritable temperament (MSRA) and risk-taking propensity (CADM2). Mendelian randomization analyses infer causal influences of earlier puberty timing on earlier first sexual intercourse, earlier first birth and lower educational attainment. In turn, likely causal consequences of earlier first sexual intercourse include reproductive, educational, psychiatric and cardiometabolic outcomes.

Concepts: Psychology, Sexual intercourse, Genetics, Age, Genome-wide association study, Behavior, Psychiatry, The Onset

47

A 42-year-old man presented to the emergency department (ED) with newly diagnosed atrial fibrillation of unknown duration. Interrogation of the patient’s wrist-worn activity tracker and smartphone application identified the onset of the arrhythmia as within the previous 3 hours, permitting electrocardioversion and discharge of the patient from the ED.

Concepts: Patient, Hospital, Atrial fibrillation, Atrial flutter, Ireland, The Onset, Dublin

45

Understanding the minimal dose of physical activity required to achieve improvement in physical functioning and reductions in disability risk is necessary to inform public health recommendations. To examine the effect of physical activity dose on changes in physical functioning and the onset of major mobility disability in The Lifestyle Interventions and Independence for Elders (LIFE) Study. We conducted a multicenter single masked randomized controlled trial that enrolled participants in 2010 and 2011 and followed them for an average of 2.6 years. 1,635 sedentary men and women aged 70-89 years who had functional limitations were randomized to a structured moderate intensity walking, resistance, and flexibility physical activity program or a health education program. Physical activity dose was assessed by 7-day accelerometry and self-report at baseline and 24 months. Outcomes included the 400 m walk gait speed, the Short Physical Performance Battery (SPPB), assessed at baseline, 6, 12, and 24 months, and onset of major mobility disability (objectively defined by loss of ability to walk 400 m in 15 min). When the physical activity arm or the entire sample were stratified by change in physical activity from baseline to 24 months, there was a dose-dependent increase in the change in gait speed and SPPB from baseline at 6, 12, and 24 months. In addition, the magnitude of change in physical activity over 24 months was related to the reduction in the onset of major mobility disability (overall P < 0.001) (highest versus the lowest quartile of physical activity change HR 0.23 ((95% CI:0.10-0.52) P = 0.001) in the physical activity arm. We observed a dose-dependent effect of objectively monitored physical activity on physical functioning and onset of major mobility disability. Relatively small increases (> 48 minutes per week) in regular physical activity participation had significant and clinically meaningful effects on these outcomes.

Concepts: Pharmacology, Epidemiology, Randomized controlled trial, Pharmaceutical industry, Clinical research, Efficacy, Walking, The Onset

33

Craving is considered a key characteristic of diverse pathologies, but evidence suggests it may be a culture-bound construct. Almost 50% of American women crave chocolate specifically around the onset of menstruation. Research does not support popular accounts implicating physiological factors in menstrual chocolate craving etiology. We tested the novel hypothesis that greater menstrual craving prevalence in the U.S. is the product of internalized cultural norms. Women of diverse backgrounds (n = 275) reported on craving frequency and triggers and completed validated measures of acculturation. Foreign-born women were significantly less likely to endorse menstrual chocolate craving (17.3%), compared to women born to U.S.-born parents (32.7%, p = .03) and second generation immigrants (40.9%, p = .001). Second generation immigrant and foreign-born women endorsing menstrual chocolate craving reported significantly greater U.S. acculturation and lower identification with their native culture than non-menstrual cravers (all p < .001). Findings inform our understanding of food cravings, with important implications for the study of cravings in other domains.

Concepts: Sociology, Culture, Immigration, Novel, The Onset, Immigration to the United States

32

Support for an extremist entity such as Islamic State (ISIS) somehow manages to survive globally online despite considerable external pressure and may ultimately inspire acts by individuals having no history of extremism, membership in a terrorist faction, or direct links to leadership. Examining longitudinal records of online activity, we uncovered an ecology evolving on a daily time scale that drives online support, and we provide a mathematical theory that describes it. The ecology features self-organized aggregates (ad hoc groups formed via linkage to a Facebook page or analog) that proliferate preceding the onset of recent real-world campaigns and adopt novel adaptive mechanisms to enhance their survival. One of the predictions is that development of large, potentially potent pro-ISIS aggregates can be thwarted by targeting smaller ones.

Concepts: Scientific method, Theory, Islam, Ad hoc, The Onset, Extremism, Isis, Osiris

30

The aim of this longitudinal study was to compare two recovery modes (active vs. passive) during a seven-week high-intensity interval training program (SWHITP) aimed to improve maximal oxygen uptake ([Formula: see text]), maximal aerobic velocity (MAV), time to exhaustion (t (lim)) and time spent at a high percentage of [Formula: see text], i.e., above 90 % (t90 [Formula: see text]) and 95 % (t95 [Formula: see text]) of [Formula: see text]. Twenty-four adults were randomly assigned to a control group that did not train (CG, n = 6) and two training groups: intermittent exercise (30 s exercise/30 s recovery) with active (IE(A), n = 9) or passive recovery (IE(P), n = 9). Before and after seven weeks with (IE(A) and IE(P)) or without (CG) high-intensity interval training (HIT) program, all subjects performed a maximal graded test to determine their [Formula: see text] and MAV. Subsequently only the subjects of IE(A) and IE(P) groups carried out an intermittent exercise test consisting of repeating as long as possible 30 s intensive runs at 105 % of MAV alternating with 30 s active recovery at 50 % of MAV (IE(A)) or 30 s passive recovery (IE(P)). Within IE(A) and IE(P), mean t (lim) and MAV significantly increased between the onset and the end of the SWHITP and no significant difference was found in t90 VO(2max) and t95 VO(2max). Furthermore, before and after the SWHITP, passive recovery allowed a longer t (lim) for a similar time spent at a high percentage of VO(2max). Finally, within IE(A), but not in IE(P), mean VO(2max) increased significantly between the onset and the end of the SWHITP both in absolute (p < 0.01) and relative values (p < 0.05). In conclusion, our results showed a significant increase in VO(2max) after a SWHITP with active recovery in spite of the fact that t (lim) was significantly longer (more than twice longer) with respect to passive recovery.

Concepts: Longitudinal study, Statistical significance, Exercise, Sociology, High-intensity interval training, The Onset, Interval training, Long slow distance

29

Despite great advances in forensic sciences in the last decades, our knowledge of the pathophysiology of ligature strangulation is still largely based on old writings from the 19th and beginning of the 20th century. The study of filmed hangings by the Working Group on Human Asphyxia has contributed to a better understanding of the agonal responses to strangulation by hanging, and judo-related studies have given some insight into the pathophysiology of manual strangulation, but the pathophysiology of ligature strangulation has remained largely unexplored so far. Three nonlethal strangulations filmed by an autoerotic practitioner are here presented. In these 3 ligature strangulations, the 35-year-old man is sitting on a chair. A pair of pajama pants is rolled once around his neck, with the extremities of the pants falling down on each side of his chest. The man is pulling the extremities of the pants with both hands to apply compression on his neck. After losing consciousness, he ceases to pull on the ligature, and the pants slowly loosen around the neck. A few seconds later, he regains consciousness and gets up from the chair. In the 3 nonlethal ligature strangulations presented in this study, the loss of consciousness occurred in 11 seconds. The loss of consciousness was closely followed by the onset of convulsions (7-11 seconds). These results are compared with the early agonal responses documented in filmed hangings and judo studies.

Concepts: 20th century, The Loss, Hanging, The Onset, Suicide methods, Strangling, Execution methods, 20th Century Fox

28

The increasing prevalence of diabetes is a major health problem. The detection and treatment of prediabetes can delay the onset of diabetes and presents an important diabetes prevention strategy.

Concepts: Health care, Nutrition, Diabetes, The Onset