Interaction of quasilocal harmonic modes and boson peak in glasses

The direct proportionality relation between the boson peak maximum in glasses, $\omega_b$, and the Ioffe-Regel crossover frequency for phonons, $\omega_d$, is established. For several investigated materials $\omega_b = (1.5\pm 0.1)\omega_d$. At the frequency $\omega_d$ the mean free path of the phonons $l$ becomes equal to their wavelength because of strong resonant scattering on quasilocal harmonic oscillators. Above this frequency phonons cease to exist. We prove that the established correlation between $\omega_b$ and $\omega_d$ holds in the general case and is a direct consequence of bilinear coupling of quasilocal oscillators with the strain field.Comment: RevTex, 4 pages, 1 figur

Sugar responses of human enterochromaffin cells depend on gut region, sex, and body mass

Gut-derived serotonin (5-HT) is released from enterochromaffin (EC) cells in response to nutrient cues, and acts to slow gastric emptying and modulate gastric motility. Rodent studies also evidence a role for gut-derived 5-HT in the control of hepatic glucose production, lipolysis and thermogenesis, and in mediating diet-induced obesity. EC cell number and 5-HT content is increased in the small intestine of obese rodents and human, however, it is unknown whether EC cells respond directly to glucose in humans, and whether their capacity to release 5-HT is perturbed in obesity. We therefore investigated 5-HT release from human duodenal and colonic EC cells in response to glucose, sucrose, fructose and α-glucoside (αMG) in relation to body mass index (BMI). EC cells released 5-HT only in response to 100 and 300 mM glucose (duodenum) and 300 mM glucose (colon), independently of osmolarity. Duodenal, but not colonic, EC cells also released 5-HT in response to sucrose and αMG, but did not respond to fructose. 5-HT content was similar in all EC cells in males, and colonic EC cells in females, but 3 to 4-fold higher in duodenal EC cells from overweight females (p < 0.05 compared to lean, obese). Glucose-evoked 5-HT release was 3-fold higher in the duodenum of overweight females (p < 0.05, compared to obese), but absent here in overweight males. Our data demonstrate that primary human EC cells respond directly to dietary glucose cues, with regional differences in selectivity for other sugars. Augmented glucose-evoked 5-HT release from duodenal EC is a feature of overweight females, and may be an early determinant of obesity.Amanda L. Lumsden, Alyce M. Martin, Emily W. Sun, Gudrun Schober, Nicole J. Isaacs, Nektaria Pezos, David A. Wattchow, Dayan de Fontgalland, Philippa Rabbitt, Paul Hollington, Luigi Sposato, Steven L. Due, Christopher K. Rayner, Nam Q. Nguyen, Alice P. Liou, V. Margaret Jackson, Richard L. Young, and Damien J. Keatin

The Physics of Star Cluster Formation and Evolution

© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00689-4.Star clusters form in dense, hierarchically collapsing gas clouds. Bulk kinetic energy is transformed to turbulence with stars forming from cores fed by filaments. In the most compact regions, stellar feedback is least effective in removing the gas and stars may form very efficiently. These are also the regions where, in high-mass clusters, ejecta from some kind of high-mass stars are effectively captured during the formation phase of some of the low mass stars and effectively channeled into the latter to form multiple populations. Star formation epochs in star clusters are generally set by gas flows that determine the abundance of gas in the cluster. We argue that there is likely only one star formation epoch after which clusters remain essentially clear of gas by cluster winds. Collisional dynamics is important in this phase leading to core collapse, expansion and eventual dispersion of every cluster. We review recent developments in the field with a focus on theoretical work.Peer reviewe

Dutch Prospective Observational Study on Prehospital Treatment of Severe Traumatic Brain Injury: The BRAIN-PROTECT Study Protocol

Background: Severe traumatic brain injury (TBI) is associated with a high mortality rate and those that survive commonly have permanent disability. While there is a broad consensus that appropriate prehospital treatment is crucial for a favorable neurological outcome, evidence to support currently applied treatment strategies is scarce. In particular, the relationship between prehospital treatments and patient outcomes is unclear. The BRAIN-PROTECT study therefore aims to identify prehospital treatment strategies associated with beneficial or detrimental outcomes. Here, we present the study protocol. Study Protocol: BRAIN-PROTECT is the acronym for BRAin INjury: Prehospital Registry of Outcome, Treatments and Epidemiology of Cerebral Trauma. It is a prospective observational study on the prehospital treatment of patients with suspected severe TBI in the Netherlands. Prehospital epidemiology, interventions, medication strategies, and nonmedical factors that may affect outcome are studied. Multivariable regression based modeling will be used to identify confounder-adjusted relationships between these factors and patient outcomes, including mortality at 30 days (primary outcome) or mortality and functional neurological outcome at 1 year (secondary outcomes). Patients in whom severe TBI is suspected during prehospital treatment (Glasgow Coma Scale score 8 in combination with a trauma mechanism or clinical findings suggestive of head injury) are identified by all four helicopter emergency medical services (HEMS) in the Netherlands. Patients are prospectively followed up in 9 participating trauma centers for up to one year. The manuscript reports in detail the objectives, setting, study design, patient inclusion, and data collection process. Ethical and juridical aspects, statistical considerations, as well as limitations of the study design are discussed. Discussion: Current prehospital treatment of patients with suspected severe TBI is based on marginal evidence, and optimal treatment is basically unknown. The BRAINPROTECT study provides an opportunity to evaluate and compare different treatment strategies with respect to patient outcomes. To our knowledge, this study project is the first large-scale prospective prehospital registry of patients with severe TBI that also collects long-term follow-up data and ma

Evidence for the recent origin of a bacterial protein-coding, overlapping orphan gene by evolutionary overprinting.

BACKGROUND: Gene duplication is believed to be the classical way to form novel genes, but overprinting may be an important alternative. Overprinting allows entirely novel proteins to evolve de novo, i.e., formerly non-coding open reading frames within functional genes become expressed. Only three cases have been described for Escherichia coli. Here, a fourth example is presented. RESULTS: RNA sequencing revealed an open reading frame weakly transcribed in cow dung, coding for 101 residues and embedded completely in the -2 reading frame of citC in enterohemorrhagic E. coli. This gene is designated novel overlapping gene, nog1. The promoter region fused to gfp exhibits specific activities and 5&#39; rapid amplification of cDNA ends indicated the transcriptional start 40-bp upstream of the start codon. nog1 was strand-specifically arrested in translation by a nonsense mutation silent in citC. This Nog1-mutant showed a phenotype in competitive growth against wild type in the presence of MgCl2. Small differences in metabolite concentrations were also found. Bioinformatic analyses propose Nog1 to be inner membrane-bound and to possess at least one membrane-spanning domain. A phylogenetic analysis suggests that the orphan gene nog1 arose by overprinting after Escherichia/Shigella separated from the other &gamma;-proteobacteria. CONCLUSIONS: Since nog1 is of recent origin, non-essential, short, weakly expressed and only marginally involved in E. coli&#39;s central metabolism, we propose that this gene is in an initial stage of evolution. While we present specific experimental evidence for the existence of a fourth overlapping gene in enterohemorrhagic E. coli, we believe that this may be an initial finding only and overlapping genes in bacteria may be more common than is currently assumed by microbiologists