1,923 research outputs found

    A LAGRANGIAN PARTICLE MODEL WITH CHEMICAL REACTIONS: APPLICATION IN REAL ATMOSPHERE

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    In this work a lagrangian particle model able to account for simple chemical reactions between NO and O3 (Alessandrini et al., 2007) has been improved in order to consider the photolysis of NO2. A system of chemical equations is numerically solved on an eulerian grid, while the particles trajectories are moved in a lagrangian frame. The NOx emissions of a power plant in real atmosphere, situated in a complex topography environment, have been considered as a test case. The meteorological model RAMS has been applied to build the wind field together with the interface code MIRS to compute turbulence parameters, requested for the dispersion simulations. The plume transitions over an air quality station, allowing for a comparison between the measured and computed concentrations of all the reaction’s compounds (NO, NO2 and O3), have been simulated by the lagrangian particle model. The simulated episodes refer to the diurnal time, when the ultraviolet radiation activates the NO2 photolysis making necessary the model complete set of chemical equations. In order to reduce computational cost and improve the accuracy of the background O3 concentration representation, the concept of concentration deficit carried by the particles is proposed and tested. This new method does not need to release a big amount of particles filling the whole domain, but only the inside plume particles should be accounted for. Comparisons between NO/NO2’s concentrations ratio are presented in term of scatter plots and statistical indexes analysis. The satisfactory results suggest that the model can be used in practical applications in real atmosphere also for regulatory purposes when the NO2 concentration limits are imposed by the legislation

    CLUMP-3D. Testing Λ\LambdaCDM with galaxy cluster shapes

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    The Λ\LambdaCDM model of structure formation makes strong predictions on concentration and shape of DM (dark matter) halos, which are determined by mass accretion processes. Comparison between predicted shapes and observations provides a geometric test of the Λ\LambdaCDM model. Accurate and precise measurements needs a full three-dimensional analysis of the cluster mass distribution. We accomplish this with a multi-probe 3D analysis of the X-ray regular CLASH (Cluster Lensing And Supernova survey with Hubble) clusters combining strong and weak lensing, X-ray photometry and spectroscopy, and the Sunyaev-Zel'dovich effect. The cluster shapes and concentrations are consistent with Λ\LambdaCDM predictions. The CLASH clusters are randomly oriented, as expected given the sample selection criteria. Shapes agree with numerical results for DM-only halos, which hints at baryonic physics being not so effective in making halos rounder.Comment: v2: 8 pages, in press on ApJL. Extended discussion on regularity. One of three new companion papers of the CLUMP-3D project (Keiichi Umetsu et al., arxiv:1804.00664; I-Non Chiu et al., arXiv:1804.00676

    Formation of interstellar complex organic molecules on water-rich ices triggered by atomic carbon freezing

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    The reactivity of interstellar carbon atoms (C) on the water-dominated ices is one of the possible ways to form interstellar complex organic molecules (iCOMs). In this work, we report a quantum chemical study of the coupling reaction of C (3^3P) with an icy water molecule, alongside possible subsequent reactions with the most abundant closed shell frozen species (NH3_3, CO, CO2_2 and H2_2), atoms (H, N and O), and molecular radicals (OH, NH2_2 and CH3_3). We found that C spontaneously reacts with the water molecule, resulting in the formation of 3^3C-OH2_2, a highly reactive species due to its triplet electronic state. While reactions with the closed-shell species do not show any reactivity, reactions with N and O form CN and CO, respectively, the latter ending up into methanol upon subsequent hydrogenation. The reactions with OH, CH3_3 and NH2_2 form methanediol, ethanol and methanimine, respectively, upon subsequent hydrogenation. We also propose an explanation for methane formation, observed in experiments through H additions to C in the presence of ices. The astrochemical implications of this work are: i) atomic C on water ice is locked into 3^3C-OH2_2, making difficult the reactivity of bare C atoms on the icy surfaces, contrary to what is assumed in astrochemical current models; and ii) the extraordinary reactivity of 3^3C-OH2_2 provides new routes towards the formation of iCOMs in a non-energetic way, in particular ethanol, mother of other iCOMs once in the gas-phase

    L'agricoltura piemontese nel 2009: Osservatorio Agroalimentare del Piemonte

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    Contributi di ricerca n. 240/2010- Indice #5- Presentazione #7- Scenario: la crisi si inasprisce e colpisce anche l'agricoltura #9- Il quadro economico generale #11- La congiuntura agricola europea e nazionale #15- La congiuntura agricola in Piemonte #19- Le politiche #25- Uno sguardo alle tematiche rurali #27- Sintesi delle annate precedenti #29- Appendice : le filiere agroalimentari del Piemonte in sintesi #3

    Investigational drugs for the treatment of endometriosis, an update on recent developments

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    Introduction: Endometriosis is a hormone-dependent benign chronic disease that requires a chronic medical therapy. Although currently available drugs are efficacious in treating endometriosis-related pain, some women experience partial or no improvement. Moreover, the recurrence of symptoms is expected after discontinuation of the therapies. Currently, new drugs are under intense clinical investigation for the treatment of endometriosis. Areas covered: This review aims to offer the reader a complete and updated overview on new investigational drugs and early molecular targets for the treatment of endometriosis. The authors describe the pre-clinical and clinical development of these agents. Expert opinion: Among the drugs under investigation, late clinical trials on gonadotropin-releasing hormone antagonists (GnRH-ant) showed the most promising results for the treatment of endometriosis. Aromatase inhibitors (AIs) are efficacious in treating endometriosis related pain symptoms but they cause significant adverse effects that limit their long-term use. New targets have been identified to produce drugs for the treatment of endometriosis, but the majority of these new compounds have only been investigated in laboratory studies or early clinical trials. Thus, further clinical research is required in order to elucidate their efficacy and safety in human

    Computational Surface Modelling of Ices and Minerals of Interstellar Interest-Insights and Perspectives

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    The universe is molecularly rich, comprising from the simplest molecule (H2) to complex organic molecules (e.g., CH3CHO and NH2CHO), some of which of biological relevance (e.g., amino acids). This chemical richness is intimately linked to the different physical phases forming Solar-like planetary systems, in which at each phase, molecules of increasing complexity form. Interestingly, synthesis of some of these compounds only takes place in the presence of interstellar (IS) grains, i.e., solid-state sub-micron sized particles consisting of naked dust of silicates or carbonaceous materials that can be covered by water-dominated ice mantles. Surfaces of IS grains exhibit particular characteristics that allow the occurrence of pivotal chemical reactions, such as the presence of binding/catalytic sites and the capability to dissipate energy excesses through the grain phonons. The present know-how on the physicochemical features of IS grains has been obtained by the fruitful synergy of astronomical observational with astrochemical modelling and laboratory experiments. However, current limitations of these disciplines prevent us from having a full understanding of the IS grain surface chemistry as they cannot provide fundamental atomic-scale of grain surface elementary steps (i.e., adsorption, diffusion, reaction and desorption). This essential information can be obtained by means of simulations based on computational chemistry methods. One capability of these simulations deals with the construction of atom-based structural models mimicking the surfaces of IS grains, the very first step to investigate on the grain surface chemistry. This perspective aims to present the current state-of-the-art methods, techniques and strategies available in computational chemistry to model (i.e., construct and simulate) surfaces present in IS grains. Although we focus on water ice mantles and olivinic silicates as IS test case materials to exemplify the modelling procedures, a final discussion on the applicability of these approaches to simulate surfaces of other cosmic grain materials (e.g., cometary and meteoritic) is given

    Hepatic pseudocystic metastasis of well-differentiated ileal neuroendocrine tumor: a case report with review of the literature

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    ABSTRACT: Imaging appearance of cyst-like changes is most frequently described in primary neuroendocrine lesions, especially pancreatic NETs. The imaging finding of a pseudocystic lesion of the liver puts in differential diagnosis many pathologies such as infectious diseases, simple biliary cysts up to biliary cystadenomas and eventually to primary or metastatic malignancies. Primary or metastatic hepatic malignancies with pseudocystic aspects are rare, and a pseudocystic aspect is reported only after neo-adjuvant treatment. Liver metastasis of untreated neuroendocrine tumors are usually solid and, to our knowledge, only two cases of neuroendocrine cystic hepatic metastases of ileal atypical carcinoids have been reported so far. We present a case of a 67 years old man with synchronous finding of an untreated hepatic pseudocystic lesion and an ileal mass histologically diagnosed as a well differentiated (G1) neuroendocrine tumor. VIRTUAL SLIDES: The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1443883503102967

    Home respiratory muscle training in patients with chronic obstructive pulmonary disease

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    The benefits of inspiratory muscle strength training in decreasing symptoms, disability or handicap of patients affected by COPD are not well established. The objective of this study was to assess the efficacy of the constant use of a new flow-volumetric inspiratory exerciser, named Respivol™, in improving respiratory functional parameters in COPD patients. Twenty consecutive ambulatory patients affected by COPD were enrolled. Each patient was assessed, before and after 3 and 6 months inspiratory exercise with Respivol™, for the following clinical parameters: maximal inspiratory pressure, maximal expiratory pressure, dyspnoea grade, quality of life by a self-administered St George questionnaire and a 6-min walking test. After a brief progressive ambulatory training programme, inspiratory exercise with Respivol™ was performed at home for 6 months. All patients used Respivol™ together with medical treatment. Maximal inspiratory pressure and maximal expiratory pressure values were significantly increased after 3 and 6 months of exercise. Dyspnoea grade was significantly reduced and the 6-min walking test showed an increase in effort tolerance, after 6 months of home training. Quality of life assessment showed an improvement, associated with a decrease of respiratory disease symptoms. Inspiratory muscle strength training with Respivol™ seems to be efficient in reducing symptoms and improving quality of life in adults with COPD
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