346 research outputs found

    Simulación y control predictivo del sistema de transporte de gas en una gran zona industrial

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    El artículo describe un enfoque para el control operativo y de supervisión de un sistema de transmisión de gas para grandes zonas industriales utilizando un modelo de control predictivo, así como métodos analíticos y de simulación. El control operativo y de supervisión del sistema de transporte de gas cubre el horizonte temporal de varias horas a varios días e implica la realización de varias acciones cíclicamente repetidas. Los autores proponen un modelo predictivo de series de tiempo del parámetro de consumo de gas considerando las condiciones climáticas de temperatura, que se amplía con base en la contabilidad de las relaciones de correlación entre los volúmenes de consumo de cada consumidor. Los métodos de control utilizados en la actualidad, reaccionando a las desviaciones actuales del régimen planificado, a priori no permiten lograr los mejores resultados. Se puede lograr un aumento significativo en la estabilidad del control y una reducción en el costo del combustible y los recursos energéticos utilizando el método de control basado en modelos predictivos. En este caso, el modelo de objeto de control se utiliza para predecir su comportamiento dentro del horizonte de tiempo seleccionado, y las acciones de control óptimas se seleccionan sobre esta base. El proceso de predecir y seleccionar acciones de control se repite periódicamente, cambiando constantemente los límites del horizonte temporal. El método descrito para cambiar el diagrama de flujo consiste en cambiar todos los flujos al mismo tiempo o en una transición preventiva y suave basada en la introducción de un diagrama de flujo ponderado para varios modos estacionarios, siempre que su desajuste se minimice en intervalos de tiempo vecinos. correspondiente a los intervalos de constancia de las solicitudes de consumo

    Ablation of Soluble Epoxide Hydrolase Reprogram White Fat to Beige-Like Fat Through an Increase in Mitochondrial Integrity, HO-1-Adiponectin in vitro and in vivo

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    We have shown that epoxyeicosatrienoic acids (EETs), specifically 11,12- and 14,15-EETs, reduce adipogenesis in human mesenchymal stem cells and mouse preadipocytes (3T-3L1). In this study, we explore the effects of soluble epoxide hydrolase (sEH) deletion on various aspects of adipocyte-function, including programing for white vs. beige-like fat, and mitochondrial and thermogenic gene-expressions. We further hypothesize that EETs and heme-oxygenase 1 (HO-1) form a synergistic, functional module whose effects on adipocyte and vascular function is greater than the effects of sEH deletion alone. In in vitro studies, we examined the effect of sEH inhibitors on MSC-derived adipocytes. MSC-derived adipocytes exposed to AUDA, an inhibitor of sEH, exhibit an increased number of small and healthy adipocytes, an effect reproduced by siRNA for sEH. in vivo studies indicate that sEH deletion results in a significant decrease in adipocyte size, inflammatory adipokines NOV, TNFalpha, while increasing adiponectin (p \u3c 0.05). These findings are associated with a decrease in body weight (p \u3c 0.05), and visceral fat (p \u3c 0.05). Importantly, sEH deletion was associated with a significant increase in Mfn1, COX 1, UCP1 and adiponectin (p \u3c 0.03). sEH deletion was manifested by a significant increase in EETs isomers 5,6-EET, 8,9-EET, 11,12-EET, and 14,15-EET and an increased EETs/DHETEs ratio. Notably, activation of HO-1 gene expression further increased the levels of EETs, suggesting that the antioxidant HO-1 system protects EETs from degradation by ROS. These results are novel in that sEH deletion, while increasing EET levels, resulted in reprograming of white fat to express mitochondrial and thermogenic genes, a phenotype characteristic of beige-fat. Thus, EETs agonist(s) and sEH inhibitors may have therapeutic potential in the treatment of metabolic syndrome and obesity

    How Exposures to Biologics Influence the Induction and Incidence of Asthma

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    A number of environmental factors can affect the development and severity of allergy and asthma; however, it can be argued that the most significant inhaled agents that modulate the development of these conditions are biologics. Sensitization to environmental allergens is an important risk factor for the development of asthma. Innate immune responses are often mediated by receptors on mononuclear cells whose primary ligands arise from microorganisms. Many pathogens, especially viruses, target epithelial cells and affect the host immune response to those pathogens. The acquired immune response to an allergen is influenced by the nature of the innate immune system. Products of innate immune responses to microbes promote T(H)1-acquired responses. In the absence of T(H)1 responses, T(H)2 responses can dominate. Central to T(H)1/T(H)2 balance is the composition of contaminants that derive from microbes. In this review we examine the biology of the response to allergens, viruses, and bacterial products in the context of the development of allergy and asthma

    Cyclooxygenase Polymorphisms and Risk of Cardiovascular Events: The Atherosclerosis Risk in Communities (ARIC) Study

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    Cyclooxygenase-derived prostaglandins modulate cardiovascular disease risk. We genotyped 2212 Atherosclerosis Risk in Communities study participants (1,023 incident coronary heart disease (CHD) cases; 270 incident ischemic stroke cases; 919 non-cases) with available DNA for polymorphisms in PTGS1 and PTGS2. Using a case–cohort design, associations between genotype and CHD or stroke risk were evaluated using proportional hazards regression. In Caucasians, the reduced function PTGS1 −1006A variant allele was significantly more common among stroke cases compared to non-cases (18.2 versus 10.6%, P = 0.027). In African Americans, the reduced function PTGS2 −765C variant allele was significantly more common in stroke cases (61.4 versus 49.4%, P = 0.032). No significant relationships with CHD risk were observed. However, aspirin utilization appeared to modify the relationship between the PTGS2 G-765C polymorphism and CHD risk (interaction P = 0.072). These findings suggest that genetic variation in PTGS1 and PTGS2 may be important risk factors for the development of cardiovascular disease events. Confirmation in independent populations is necessary

    Overexpression of Cytochrome P450 Epoxygenases Prevents Development of Hypertension in Spontaneously Hypertensive Rats by Enhancing Atrial Natriuretic Peptide

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    Cytochrome P450 (P450)-derived epoxyeicosatrienoic acids (EETs) exert well recognized vasodilatory, diuretic, and tubular fluid-electrolyte transport actions that are predictive of a hypotensive effect. The study sought to determine the improvement of hypertension and cardiac function by overexpressing P450 epoxygenases in vivo. Long-term expression of CYP102 F87V or CYP2J2 in spontaneously hypertensive rats (SHR) was mediated by using a type 8 recombinant adeno-associated virus (rAAV8) vector. Hemodynamics was measured by a Millar Instruments, Inc. (Houston, TX) microtransducer catheter, and atrial natriuretic peptide (ANP) mRNA levels were tested by real-time polymerase chain reaction. Results showed that urinary excretion of 14,15-EET was increased at 2 and 6 months after injection with rAAV-CYP102 F87V and rAAV-CYP2J2 compared with controls (p < 0.05). During the course of the 6-month study, systolic blood pressure significantly decreased in P450 epoxygenase-treated rats, but the CYP2J2-specific inhibitor C26 blocked rAAV-CYP2J2-induced hypotension and the increase in EET production. Cardiac output was improved by P450 epoxygenase expression at 6 months (p < 0.05). Furthermore, cardiac collagen content was reduced in P450 epoxygenase-treated rats. ANP mRNA levels were up-regulated 6- to 14-fold in the myocardium, and ANP expression was significantly increased in both myocardium and plasma in P450 epoxygenase-treated rats. However, epidermal growth factor (EGF) receptor antagonist 4-(3′-chloroanilino)-6,7-dimethoxy-quinazoline (AG-1478) significantly attenuated the increase in the EET-induced expression of ANP in vitro. These data indicate that overexpression of P450 epoxygenases attenuates the development of hypertension and improves cardiac function in SHR, and that these effects may be mediated, at least in part, by ANP via activating EGF receptor

    Using social cognitive career theory to understand why students choose to study computer science

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    The aim of this research is to use Social Cognitive Career Theory (SCCT) to identify and understand reasons why students choose to study Computer Science (CS) at university. SCCT focuses on students’ prior experience, social support, self-efficacy and outcome expectation. The research is part motivated by the desire to increase female participation rates in CS, particularly in the UK. Policymakers can use the factors that both females and males identify as influencing their choice of studying CS to enhance the experiences of all students prior to coming to university, but female students in particular. The study uses a semi-structured interview with 17 mixed gender subjects currently studying CS at three Scottish universities. The findings are that social support from family, teachers, friends and mentors is a particularly important factor in choosing to study CS, especially for female subjects. The career paths offered by a CS degree is another major factor, not just the potential jobs, but also the general value of a CS education and the potential to make useful contributions to society. School education appeared to have limited influence, though exposure to problem solving, programming, online self-learning and internships are positive influences. The stereotypical view of CS students as ‘geeks’ is outdated and unhelpful – it is more appropriate to see them as ‘analytical’ or ‘over-achievers’. Subjects make many suggestions for improving the CS education provided at school, especially to make it more attractive to females, including: make it compulsory, teach it earlier, include more programming and problem solving, and increase the visibility of female exemplars and role models

    Identification and functional characterization of polymorphisms in human cyclooxygenase-1 (PTGS1)

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    Cyclooxygenase-1 (COX-1, PTGS1) catalyzes the conversion of arachidonic acid to prostaglandin H2, which is subsequently metabolized to various biologically active prostaglandins. We sought to identify and characterize the functional relevance of genetic polymorphisms in PTGS1

    Institutional creativity and pathologies of potential space: The modern university

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    This paper proposes the applicability of object relations psychoanalytic conceptions of dialogue (Ogden, 1986, 1993) to thinking about relationships and relational structures and their governance in universities. It proposes that: the qualities of dialogic relations in creative institutions are the proper index of creative productivity; that is of, as examples, ’thinking’ (Evans, 2004), ’emotional learning’ (Salzberger-Wittenburg et al., 1983) or ’criticality’ (Barnett, 1997); contemporary institutions’ explicit preoccupation in assuring, monitoring and managing creative ’dialogue’ can, in practice, pervert creative processes and thoughtful symbolic productivity, thus inhibiting students’ development and the quality of ’thinking space’ for teaching and research. In this context the paper examines uncanny and perverse connections between Paulo Freire’s (1972) account of educational empowerment and dialogics (from his Pedagogy of the oppressed) to the consumerist (see, for example, Clarke & Vidler, 2005) rhetoric of student empowerment, as mediated by some strands of managerialism in contemporary higher education. The paper grounds its critique of current models of dialogue, feedback loops, audit and other mechanisms of accountability (Power, 1997; Strathern, 2000), in a close analysis of how creative thinking emerges. The paper discusses the failure to maintain a dialogic space in humanities and social science areas in particular, exploring psychoanalytic conceptions from Donald Winnicott (1971), Milner (1979), Thomas Ogden (1986) and Csikszentmihalyi (1997). Coleridge’s ideas about imagination as the movement of thought between subjective and objective modes are discussed in terms of both intra- and inter-subjective relational modes of ’dialogue’, which are seen as subject to pathology in the pathologically structured psychosocial environment. Current patterns of institutional governance, by micromanaging dialogic spaces, curtail the ’natural’ rhythms and temporalities of imagination by giving an over-emphasis to the moment of outcome, at the expense of holding the necessary vagaries of process in the institutional ’mind’. On the contrary, as this paper argues, creative thinking lies in sporadic emergences at the conjunction of object/(ive) outcome and through (thought) processes
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