A second-order conditional moment closure model for the simulation of a lifted turbulent flame

This paper presents the results of a second-order closure Conditional Moment Closure model applied to a lifted turbulent H 2 -air flame. The objective is to find out how a second-order closure will modify the lift-off height compared to first-order results. A 10-step chemical mechanism is used to predict rates of reaction in hydrogen-air mixtures but the second-order correction terms are calculated using one-step chemistry. First a progress variable for this reduced mechanism is defined and an additional equation for its conditional variance is derived. The level of the conditional fluctuation is found to be around 30% of its maximum value for stoichiometric mixtures in the flame stabilisation area. The second-order closure has a distinct effect on the flame position determined in the simulations

Rotation mentale et différences sexuelles: influence des axes directionnels extraits de l'environnement

Les tâches nécessitant des manipulations et des transformations de figures géométriques et de formes, comme les tâches de rotation mentale, donnent lieu à des différences de performance entre hommes et femmes qui restent intrigantes. Plusieurs hypothèses ont été proposées pour expliquer ces différences. La plus récurrente porte sur les différences de stratégie globale vs locale utilisées pour traiter l'information. Bien que cette conjecture soit intéressante, elle reste difficile à opérationnaliser car elle englobe tous les mécanismes cognitifs (acquisition, conservation et récupération de l'information). Ce travail prend la forme d'un retour aux sources dans la mesure où il se base sur des recherches anciennes qui ont montré que les hommes perçoivent significativement mieux que les femmes la verticale et l'horizontale. Il teste l'hypothèse selon laquelle les hommes, comparativement aux femmes, présentent une plus forte indépendance au champ perceptif visuel et sont donc plus susceptibles d'utiliser la verticalité et l'horizontalité pour résoudre une tâche de rotation mentale. Une première série d'expériences s'est penchée sur la perception spatiale pour évaluer son impact sur la résolution d'une tâche impliquant la rotation mentale. Les résultats ont montré que seuls les hommes se référaient à la verticalité et à l'horizontalité pour résoudre la tâche. Une seconde série d'expériences ont investigué l'effet de la présence, ou absence, d'axes directionnels directement liés à une tâche de rotation mentale. Elles ont été menées également en environnement réel afin d'évaluer comment le déplacement actif ou passif, correspondant à un changement de perspective en lieu et place d'une rotation mentale, module la performance des hommes et des femmes. Les résultats n'ont pas mis en évidence de différence sexuelle. Notre hypothèse est vérifiée puisque c'est uniquement lorsque la tâche ne présente pas d'axes orthogonaux évidents mais implicites que seuls les hommes, plus indépendants au champ perceptif visuel que les femmes, utilisent la perception de la verticalité et de l'horizontalité pour améliorer leur compétence en rotation mentale. -- Tasks that require manipulation and transformation of geometric shapes and forms, like tasks of mental rotation and give rise to differences in performance between men and women, remain intriguing. Several hypotheses have been proposed to explain these differences. The most recurring hypothesis addresses differences in global versus local strategies for processing information. While this conjecture is interesting, it remains difficult to study because it encompasses all the cognitive mechanisms (acquisition, retention and output). This work returns to the sources, which are based on earlier research that shows that men are significantly better than women at perceiving verticality and horizontality. It tests the hypothesis according to which men, as compared to women, exhibit a greater independence on the perceptive visual field, and therefore are more susceptible to utilizing the verticality and the horizontality to solve a mental rotation task. A first set of experiments examined spatial perception in order to assess its impact on the resolution of a task involving mental rotation. The results showed that only men referred to the verticality and the horizontality to solve the task. A second series of experiments investigated the effect of a presence, or absence of directional axes directed tied to the task of mental rotation. They were also conducted in a real world environment to evaluate how the active or passive displacement, corresponding to a change in perspective instead of a mental rotation, modulates the performance of men and women. The results did not show sex differences. Our hypothesis is verified: it is only when the task presents no obvious, but implicit orthogonal axes that men, who exhibit a greater independence on the perceptive visual field than women, use the perception of verticality and horizontality to improve their competence in mental rotation

Acute thiamethoxam toxicity in honeybees is not enhanced by common fungicide and herbicide and lacks stress-induced changes in mRNA splicing

Securing food supply for a growing population is a major challenge and heavily relies on the use of agrochemicals to maximize crop yield. It is increasingly recognized, that some neonicotinoid insecticides have a negative impact on non-target organisms, including important pollinators such as the European honeybee Apis mellifera. Toxicity of neonicotinoids may be enhanced through simultaneous exposure with additional pesticides, which could help explain, in part, the global decline of honeybee colonies. Here we examined whether exposure effects of the neonicotinoid thiamethoxam on bee viability are enhanced by the commonly used fungicide carbendazim and the herbicide glyphosate. We also analysed alternative splicing changes upon pesticide exposure in the honeybee. In particular, we examined transcripts of three genes: (i) the stress sensor gene X box binding protein-1 (Xbp1), (ii) the Down Syndrome Cell Adhesion Molecule (Dscam) gene and iii) the embryonic lethal/abnormal visual system (elav) gene, which are important for neuronal function. Our results showed that acute thiamethoxam exposure is not enhanced by carbendazim, nor glyphosate. Toxicity of the compounds did not trigger stress-induced, alternative splicing in the analysed mRNAs, thereby leaving dormant a cellular response pathway to these man-made environmental perturbations

Hypertriglyceridemia: a potential side effect of propofol sedation in critical illness

Purpose: Hypertriglyceridemia (hyperTG) is common among intensive care unit (ICU) patients, but knowledge about hyperTG risk factors is scarce. The present study aims to identify risk factors favoring its development in patients requiring prolonged ICU treatment. Methods: Prospective observational study in the medicosurgical ICU of a university teaching hospital. All consecutive patients staying ≥4days were enrolled. Potential risk factors were recorded: pathology, energy intake, amount and type of nutritional lipids, intake of propofol, glucose intake, laboratory parameters, and drugs. Triglyceride (TG) levels were assessed three times weekly. Statistics was based on two-way analysis of variance (ANOVA) and linear regression with potential risk factors. Results: Out of 1,301 consecutive admissions, 220 patients were eligible, of whom 99 (45%) presented hyperTG (triglycerides >2mmol/L). HyperTG patients were younger, heavier, with more brain injury and multiple trauma. Intake of propofol (mg/kg/h) and lipids' propofol had the highest correlation with plasma TG (r 2=0.28 and 0.26, respectively, both p<0.001). Infection and inflammation were associated with development of hyperTG [C-reactive protein (CRP), r 2=0.19, p=0.004]. No strong association could be found with nutritional lipids or other risk factors. Outcome was similar in normo- and hyperTG patients. Conclusions: HyperTG is frequent in the ICU but is not associated with adverse outcome. Propofol and accompanying lipid emulsion are the strongest risk factors. Our results suggest that plasma TG should be monitored at least twice weekly in patients on propofol. The clinical consequences of propofol-related hyperTG should be investigated in further studie

EXPLORATORY INVESTIGATION OF MULTIPLE MAPPING CLOSURE AS A MIXING MODEL IN LES-CMC

Abstract The scalar dissipation rate is a key quantity in turbulent combustion modelling, in particular for Conditional Moment Closure (CMC). Within the CMC framework, its conditional average at a particular value of mixture fraction is of special interest. The present study examines the deterministic version of Multiple Mapping Closure (MMC) to evaluate the conditionally filtered scalar dissipation rate in the filtered CMC equations in the context of Large Eddy Simulation (LES). The objectives of the present investigation are (i) to use MMC to model the conditionally filtered scalar dissipation rate needed in LES-CMC and (ii) to determine if MMC is a viable option in the proposed framework. The paper presents our first results and focuses on the MMC equation, the role of each term in the MMC governing equation and the submodels needed. One major scalar is selected, mixture fraction. The MMC transport equation is implemented in a LES code coupled with CMC to simulate a lifted jet flame in a vitiated coflow. At this initial stage of the present MMC study, it is useful to separate the MMC results and investigate the MMC operation and modelling alone before solving LES, CMC and MMC together. Thus, the MMC equation is solved starting from frozen flow, mixing and temperature fields. Discussion is focused on the models of the MMC unclosed terms and their impact on the prediction of the mapping function and the conditionally filtered scalar dissipation rate. The issue related to low levels of predicted subgrid variance in MMC compared to what is predicted in the LES solver is investigated. Introduction The scalar dissipation rate is a key quantity in turbulent combustion modelling, in particular for flamelet, Conditional Moment Closure (CMC) and Probability Density Function (PDF) approaches [1]. The scalar dissipation rate, N, represents the rate of mixing at the molecular level and is proportional to the mean square gradient of the scalar, Z, such as N ≡ D ∇Z ·∇Z, where D is the molecular diffusivity of Z. Within the CMC framework, its conditional average at a particular value, η, of mixture fraction, Z is of special interest with N|η = D∇Z · ∇Z|Z = η . The angular brackets denote a conditional average over an ensemble of realizations of the flow, subject to the condition to the right of the vertical bar. Accurate modelling of the conditional scalar dissipation rate is crucial, as it appears in both the conditional species transport and temperature equations. However, evaluation of N|η is not straightforward. Further, CMC requires solution of the transport equations for the conditional averages to be consistent with that of the PDF transport equatio

Mechanical characterization of porous Ti base alloys produced by sintering space-holder method

[ES] La búsqueda de materiales adecuados para su uso como implante implica una mayor investigación sobre los biomateriales, como lo son el titanio y sus aleaciones. Respecto a sus propiedades mecánicas, se debe garantizar una resistencia mecánica suficiente como para soportar cargas en uso, al igual que su rigidez ha de ser parecida a la del hueso humano. En el presente trabajo se miden diferentes propiedades mecánicas de materiales porosos de titanio y de la aleación Ti6Al4V, producidos por vía pulvimetalúrgica mediante sinterización con espaciador. Los resultados muestran la relación entre la porosidad y las propiedades mecánicas, indicando los casos en los que se presenta un compromiso entre la rigidez y la resistencia mecánica.[EN] The search of suitable materials for use as an implant involves more research of biomaterials, like titanium and its alloys. Regarding their mechanical properties, it must be guaranteed mechanical strength to support loads in use, as well as its stiffness must be similar to the bone. In this paper it have been measured several mechanical properties of porous titanium and Ti6Al4V alloy, produced by sintering powder metallurgy with space-holder method. The results show the relationship between porosity and mechanical properties and it is indicated in which cases it is presented a compromise between the stiffness and mechanical strength.Los autores agradecen al área de Ciencia de Materiales e Ingeniería Metalúrgica de la Universidad de Sevilla la ayuda prestada en el cálculo de la rigidez por ultrasonidos. Igualmente, los autores desean agradecer la financiación obtenida por el Ministerio de Ciencia e Innovación (proyecto PET2008_0158_02) y a la beca Grisolia /2009/040.Tojal Domenech, C.; Devaud, J.; Amigó, V.; Calero, JA. (2010). Caracterización mecánica de aleaciones porosas, base Ti, producidas mediante la técnica de sinterización con espaciador. Revista de Metalurgia. 46:27-32. https://doi.org/10.3989/revmetalmadrid.02.2XIIPMSS27324

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

Liver resection after chemotherapy and tumour downsizing in patients with initially unresectable colorectal cancer liver metastases

AbstractObjectivesAmong patients with initially unresectable colorectal cancer liver metastases (CLM), a subset are rendered resectable following the administration of systemic chemotherapy. This study reports the results achieved in liver resections performed at a single hepatobiliary referral centre after downsizing chemotherapy in patients with initially unresectable CLM.MethodsAll liver resections for CLM performed over a 10-year period at the Toronto General Hospital were considered. Data on initially non-resectable patients who received systemic therapy and later underwent surgery were included for analysis.ResultsBetween January 2002 and July 2012, 754 liver resections for CLM were performed. A total of 24 patients were found to meet the study inclusion criteria. Bilobar CLM were present in 23 of these 24 patients. The median number of tumours was seven (range: 2–15) and median tumour size was 7.0cm (range: 1.0–12.8cm) before systemic therapy. All patients received oxaliplatin- or irinotecan-based chemotherapy. Fourteen patients received combined treatment with bevacizumab. Negative margin (R0) resection was accomplished in 21 of 24 patients. There was no perioperative mortality. Ten patients suffered perioperative morbidity. Eighteen patients suffered recurrence of disease within 9 months. Rates of disease-free survival at 1, 2 and 3 years were 47.6% [95% confidence interval (CI) 30.4–74.6%], 23.8% (95% CI 11.1–51.2%) and 19.0% (95% CI 7.9–46.0%), respectively. Overall survival at 1, 2 and 3 years was 91.5% (95% CI 80.8–100%), 65.3% (95% CI 48.5–88.0%) and 55.2% (95% CI 37.7–80.7%), respectively.ConclusionsLiver resection in initially unresectable CLM can be performed with low rates of morbidity and mortality in patients who respond to systemic chemotherapy, although these patients do experience a high frequency of disease recurrence

Neuroactive Steroid 3α-Hydroxy-5α-Pregnan-20-One Modulates Electrophysiological and Behavioral Actions of Ethanol

Neuroactive steroids are synthesize

Memory consolidation in honey bees is enhanced by down-regulation of Down syndrome cell adhesion molecule and changes its alternative splicing

Down syndrome cell adhesion molecule (Dscam) gene encodes a cell adhesion molecule required for neuronal wiring. A remarkable feature of arthropod Dscam is massive alternative splicing generating thousands of different isoforms from three variable clusters of alternative exons. Dscam expression and diversity arising from alternative splicing have been studied during development, but whether they exert functions in adult brains has not been determined. Here, using honey bees, we find that Dscam expression is critically linked to memory retention as reducing expression by RNAi enhances memory after reward learning in adult worker honey bees. Moreover, alternative splicing of Dscam is altered in all three variable clusters after learning. Since identical Dscam isoforms engage in homophilic interactions, these results suggest a mechanism to alter inclusion of variable exons during memory consolidation to modify neuronal connections for memory retention