A semi-implicit, second-order-accurate numerical model for multiphase underexpanded volcanic jets

Abstract. An improved version of the PDAC (Pyroclastic Dispersal Analysis Code, Esposti Ongaro et al., 2007) numerical model for the simulation of multiphase volcanic flows is presented and validated for the simulation of multiphase volcanic jets in supersonic regimes. The present version of PDAC includes second-order time- and space discretizations and fully multidimensional advection discretizations in order to reduce numerical diffusion and enhance the accuracy of the original model. The model is tested on the problem of jet decompression in both two and three dimensions. For homogeneous jets, numerical results are consistent with experimental results at the laboratory scale (Lewis and Carlson, 1964). For nonequilibrium gas–particle jets, we consider monodisperse and bidisperse mixtures, and we quantify nonequilibrium effects in terms of the ratio between the particle relaxation time and a characteristic jet timescale. For coarse particles and low particle load, numerical simulations well reproduce laboratory experiments and numerical simulations carried out with an Eulerian–Lagrangian model (Sommerfeld, 1993). At the volcanic scale, we consider steady-state conditions associated with the development of Vulcanian and sub-Plinian eruptions. For the finest particles produced in these regimes, we demonstrate that the solid phase is in mechanical and thermal equilibrium with the gas phase and that the jet decompression structure is well described by a pseudogas model (Ogden et al., 2008). Coarse particles, on the other hand, display significant nonequilibrium effects, which associated with their larger relaxation time. Deviations from the equilibrium regime, with maximum velocity and temperature differences on the order of 150 m s−1 and 80 K across shock waves, occur especially during the rapid acceleration phases, and are able to modify substantially the jet dynamics with respect to the homogeneous case

The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope V. Optimal algorithms for planning multi-object spectroscopic observations

We present an overview of the capabilities and key algorithms employed in the so-called eMPT software suite developed for planning scientifically optimized, multi-object spectroscopic (MOS) observations with the Micro-Shutter Array (MSA) of the Near-Infrared Spectrograph (NIRSpec) instrument on board the James Webb Space Telescope (JWST), the first multi-object spectrograph to operate in space. NIRSpec MOS mode is enabled by a programmable MSA, a regular grid of ~250,000 individual apertures that projects to a static, semi-regular pattern of available slits on the sky and makes the planning and optimization of an MSA observation a rather complex task. As such, the eMPT package is offered to the NIRSpec user community as a supplement to the MSA Planning Tool (MPT) included in the STScI Astronomer's Proposal Tool (APT) to assist in the planning of NIRSpec MOS proposals requiring advanced functionality to meet ambitious science goals. The eMPT produces output that can readily be imported and incorporated into the user's observing program within the APT to generate a customized MPT MOS observation. Furthermore, its novel algorithms and modular approach make it highly flexible and customizable, providing users the option to finely control the workflow and even insert their own software modules to tune their MSA slit masks to the particular scientific objectives at hand

From autism to eating disorders and more: The role of oxytocin in neuropsychiatric disorders

Oxytocin (oxy) is a pituitary neuropeptide hormone synthesized from the paraventricular and supraoptic nuclei within the hypothalamus. Like other neuropeptides, oxy can modulate a wide range of neurotransmitter and neuromodulator activities. Additionally, through the neurohypophysis, oxy is secreted into the systemic circulation to act as a hormone, thereby influencing several body functions. Oxy plays a pivotal role in parturition, milk let-down and maternal behavior and has been demonstrated to be important in the formation of pair bonding between mother and infants as well as in mating pairs. Furthermore, oxy has been proven to play a key role in the regulation of several behaviors associated with neuropsychiatric disorders, including social interactions, social memory response to social stimuli, decision-making in the context of social interactions, feeding behavior, emotional reactivity, etc. An increasing body of evidence suggests that deregulations of the oxytocinergic system might be involved in the pathophysiology of certain neuropsychiatric disorders such as autism, eating disorders, schizophrenia, mood, and anxiety disorders. The potential use of oxy in these mental health disorders is attracting growing interest since numerous beneficial properties are ascribed to this neuropeptide. The present manuscript will review the existing findings on the role played by oxy in a variety of distinct physiological and behavioral functions (Figure 1) and on its role and impact in different psychiatric disorders. The aim of this review is to highlight the need of further investigations on this target that might contribute to the development of novel more efficacious therapies

SYNBIO® Probiotic and Antioxidant Dietary Supplementation: Clinical Trial Evaluation of Potential Effects on Airline Flight Crew Members' Well-Being

The irregular lifestyle of airline crew members, wide/adverse job-related exposures, and the impact of temporary hypoxia on gut microbiota well-being have increased concern about the daily recommended dose of certain nutrients among flight crew. The aim of this study was to determine if daily consumption of a SYNBIO (R) probiotics-elderberry extract supplement (ACTIVE) may contribute to the well-being of flight attendants. Forty healthy crew members enrolled in a double-blind, randomized, placebo-controlled study consumed one ACTIVE capsule/day or placebo for 30 days. Bowel well-being, health-related quality of life, and gastrointestinal tolerance were assessed by validated questionnaires. Saliva and fecal samples were analyzed to determine secretory immunoglobulin-A (sIgA) levels and to characterize gut microbiota composition, respectively. ACTIVE subjects presented a physiological improvement and a statistically significant higher Psychological General Well-Being Index (PGWBI) global score compared to PLACEBO subjects. The ACTIVE subjects showed significantly increased levels of lactobacilli and bifidobacteria compared to the PLACEBO group, while a significant increase in lactobacilli and a significant reduction in Enterobacteriaceae were registered when compared with the beginning of supplementation, confirming the persistence of probiotics in the gastrointestinal tract and the direct antagonism and competitive exclusion effects. Additionally, sIgA levels were significantly higher in the ACTIVE group compared to the baseline and to the PLACEBO group at the end of supplementation. The ACTIVE supplementation might be beneficial to airline crew members, improving their physiological state, their immune defenses, and the strength and efficiency of their gastrointestinal tract when responding to stressful conditions

Predicting success in the worldwide start-up network

By drawing on large-scale online data we construct and analyze the time-varying worldwide network of professional relationships among start-ups. The nodes of this network represent companies, while the links model the flow of employees and the associated transfer of know-how across companies. We use network centrality measures to assess, at an early stage, the likelihood of the long-term positive performance of a start-up, showing that the start-up network has predictive power and provides valuable recommendations doubling the current state of the art performance of venture funds. Our network-based approach not only offers an effective alternative to the labour-intensive screening processes of venture capital firms, but can also enable entrepreneurs and policy-makers to conduct a more objective assessment of the long-term potentials of innovation ecosystems and to target interventions accordingly

Effects of the satiety signal oleoylethanolamide on binge-like food consumption in female rats

Several lines of evidence document the association between eating disorders and modern lifestyle, encompassing calorie-rich diets and psychological stress. Binge-eating disorder (BED) is a eating disorder characterized by excessive consumption of food in a short period of time, along with loss of control and psychological distress. Among the networks that partake in the neurobiological bases of BED a large body of evidence supports the activation of the hypothalamic-pituitary-adrenal stress (HPA) axis. Pharmacological treatments for BED are limited thus highlighting the need to identify novel targets that could lead to the development of more effective therapies. A large body of evidence has accumulated on the role played by the lipid signal oleoylethanolamide (OEA) as a pharmacological target for controlling aberrant eating disorders. As a drug, OEA reduces food intake and body weight gain in laboratory rodents by inducing a state of satiety. Additionaly, OEA dampens the hyperactivity of the HPA axis and ameliorates the effects of stress. On the bases of these premises, in the present study we investigated the effects of OEA on high palatable food (HPF) intake in a rat model of BED. Moreover, we assessed the impact of OEA on the corticotropin-releasing factor (CRF) system which plays a critical role in stress and on the oxytocinergic system which is crucial in mediating the pro-satiety effect of OEA. We used female rats with a history of intermittent food restriction which show binge-like palatable food consumption after the exposure to a “frustration stress”. On the test day, we either exposed or did not expose the rats to the sight of the palatable food (frustration stress) before assessing food consumption. OEA was administered at three different doses (2.5, 5, 10 mg/kg i.p.) and HPF intake was monitored over 2h. After the behavioural experiment brains were collected and in-situ hybridization experiment was performed to analyse CRF and oxytocin mRNA expression in selected brain areas. Our results demonstrate that OEA (10 mg/kg) was able to selectively prevent binge eating; the antibinge effect was accompained by a reduction of CRF mRNA within the central-amygdala. Finally, in keeping with our previous observations we found that the antibinge effect of OEA was accompanied by a significant increase of oxytocin mRNA at hypothalamic level. In the current study, we provide for the first time evidence to support that the endogenous fatty-gut lipid OEA exerts a selective inhibitory effects on binge-like eating behavior in female rats, supporting the hypothesis that OEA might represent a novel potential pharmacological target for the treatment of aberrant eating patterns

Detection of Helicobacter pylori by PCR on gastric biopsy specimens taken for CP test: comparison with histopathological analysis.

The aims of the present study were: (i) to assess whether H. pylori could be succesfully detected by PCR from the same biopsy sample used for CPtest; and ii) to evaluate CPtest comparatively to both PCR and histology for detection of H. pylori infection in dyspeptic patients. Three antral gastric biopsies were collected from each of 80 consecutive dyspeptic patients undergoing oesophagogastroduodenoscopy. Two biopsies were for histology (gold standard), one for CPtest, scored at 20min, 1h and 24h for the presence of urease activity. Gastric biopsy was then removed from CPtest and used for ureC-targeted PCR. Fifty-five (68.7%) patients were positive for H. pylori infection by histology. CPtest yielded an overall diagnostic accuracy of 93.8% (95% CI: 91–96.4%), regardless of observation period. No erroneous categorization of H. pylori status occurred using PCR, yielding sensitivity, specificity, positive and negative predictive values, and overall diagnostic accuracy of 100%. Our results suggest that H. pylori can be detected by PCR in gastric biopsies previously taken for CPtest, so reducing the workload of the endoscopist by saving additional biopsies for culture analysis and susceptibility tests