979 resultados para External control
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The Centre de Recherche sur les Méningites et les Schistosomes (CERMES) is a research institute depending on the Organisation de Coordination et de Coopération pour la lutte contre les Grandes Endémies - a West African Organization for Public Health - devoted to the studies on schistosomiasis and meningitis. The staff includes 32 persons with 11 scientists and one financial officer. The activities of the CERMES involving schistosomiasis concern three research units: (a) ecology of human and animal schistosomiasis transmission; the CERMES defined the different patterns of schistosomiasis transmission in Niger (involving African dry savana); in this field, we have shown, (i) the existence of important variability in conditions of transmission of S. haematobium and, (ii) natural hybridization between parasitic species of the ruminants (S. bovis and S. curassoni) and genetic interaction between human and animal parasites; (b) definition of morbidity indicators usable for rapid assessment methods, for appraisal of the severity of the disease and for the evaluation of the efficiency of control methods; we have established the correlation between ultrasonographic data and some cheap and simple field indicators; (c) immune response and protective immunity induced by recombinant glutathion S-transferase (Sm28, Sb28 and Sh28) in homologous and heterologous animal models including goats, sheep and non human primates (Erythrocebus patas). In Niger, we participate in all control programs against schistosomiasis to define control strategies, to supervise operations and to participate in their evaluation with external experts. International collaborations constitute a frame including four laboratories in Africa and six laboratories in developed countries (Europe and USA)
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PURPOSE: The objective of this study was to investigate the additional burdens in terms of pain, prolongation of surgery and morbidity which is added to elective caesarean section if umbilical hernia suture repair is performed simultaneously. Secondly, patient's satisfaction and hernia recurrence rate were assessed. METHODS: Consecutive women with symptomatic umbilical hernia undergoing internal or external suture repair during elective caesarean were included in this retrospective cohort-control study. Data on post-operative pain, duration of surgery and morbidity of a combined procedure were collected. These patients were matched 1:10 to women undergoing caesarean section only. Additionally, two subgroups were assessed separately: external and internal suture hernia repair. These subgroups were compared for patient's satisfaction, cosmesis, body image and recurrence rate. RESULTS: Fourteen patients with a mean age of 37 years were analysed. Internal suture repair (n = 7) prolonged caesarean section by 20 min (p = 0.001) and external suture repair (n = 7) by 34 min (p < 0.0001). Suture repair did not increase morphine use (0.38 ± 0.2 vs. 0.4 ± 02 mg/kg body weight), had no procedure-related morbidity and prolonged hospitalization by 0.5 days (p = 0.01). At a median follow-up of 37 (5-125) months, two recurrences in each surgical technique, internal and external suture repair, occurred (28 %). Body image and cosmesis score showed a higher level of functioning in internal suture repair (p = 0.02; p = 0.04). DISCUSSION: Despite a high recurrence rate, internal suture repair of a symptomatic umbilical hernia during elective caesarean section should be offered to women if requested. No additional morbidity or scar is added to caesarean section. Internal repair is faster, and cosmetic results are better, additional skin or fascia dissection is avoided, and it seems to be as effective as an external approach. Yet, women must be informed on the high recurrence rate.
Identification and Semiactive Control of Smart Structures Equipped with Magnetorheological Actuators
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This paper deals with the problem of identification and semiactive control of smart structures subject to unknown external disturbances such as earthquake, wind, etc. The experimental setup used is a 6-story test structure equipped with shear-mode semiactive magnetorheological actuators being installed in WUSCEEL. The experimental results obtained have verified the effectiveness of the proposed control algorithms
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In Guatemala, the Ministry of Health (MoH) began a vector control project with Japanese cooperation in 2000 to reduce the risk of Chagas disease infection. Rhodnius prolixus is one of the principal vectors and is targeted for elimination. The control method consisted of extensive residual insecticide spraying campaigns, followed by community-based surveillance with selective respraying. Interventions in nine endemic departments identified 317 villages with R. prolixus of 4,417 villages surveyed. Two cycles of residual insecticide spraying covered over 98% of the houses in the identified villages. Fourteen villages reinfestated were all resprayed. Between 2000-2003 and 2008, the number of infested villages decreased from 317 to two and the house infestation rate reduced from 0.86% to 0.0036%. Seroprevalence rates in 2004-2005, when compared with an earlier study in 1998, showed a significant decline from 5.3% to 1.3% among schoolchildren in endemic areas. The total operational cost was US$ 921,815, where the cost ratio between preparatory, attack and surveillance phases was approximately 2:12:1. In 2008, Guatemala was certified for interruption of Chagas disease transmission by R. prolixus. What facilitated the process was existing knowledge in vector control and notable commitment by the MoH, as well as political, managerial and technical support by external stakeholders.
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House re-invasion by native triatomines after insecticide-based control campaigns represents a major threat for Chagas disease vector control. We conducted a longitudinal intervention study in a rural section (Area III, 407 houses) of Pampa del Indio, northeastern Argentina, and used wing geometric morphometry to compare pre-spray and post-spray (re-infestant bugs) Triatoma infestanspopulations. The community-wide spraying with pyrethroids reduced the prevalence of house infestation by T. infestans from 31.9% to < 1% during a four-year follow-up, unlike our previous studies in the neighbouring Area I. Two groups of bug collection sites differing in wing shape variables before interventions (including 221 adults from 11 domiciles) were used as a reference for assigning 44 post-spray adults. Wing shape variables from post-spray, high-density bug colonies and pre-spray groups were significantly different, suggesting that re-infestant insects had an external origin. Insects from one house differed strongly in wing shape variables from all other specimens. A further comparison between insects from both areas supported the existence of independent re-infestation processes within the same district. These results point to local heterogeneities in house re-infestation dynamics and emphasise the need to expand the geographic coverage of vector surveillance and control operations to the affected region.
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This paper deals with the problem of semiactive vibration control of civil engineering structures subject to unknown external disturbances (for example, earthquakes, winds, etc.). Two kinds of semiactive controllers are proposed based on the backstepping control technique. The experimental setup used is a 6-story test structure equipped with shear-mode semiactive magnetorheological dampers being installed in the Washington University Structural Control and Earthquake Engineering Laboratory (WUSCEEL). The experimental results obtained have verified the effectiveness of the proposed control algorithms
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We performed a comprehensive study to assess the fit for purpose of four chromatographic conditions for the determination of six groups of marine lipophilic toxins (okadaic acid and dinophysistoxins, pectenotoxins, azaspiracids, yessotoxins, gymnodimine and spirolides) by LC-MS/MS to select the most suitable conditions as stated by the European Union Reference Laboratory for Marine Biotoxins (EURLMB). For every case, the elution gradient has been optimized to achieve a total run-time cycle of 12 min. We performed a single-laboratory validation for the analysis of three relevant matrices for the seafood aquaculture industry (mussels, pacific oysters and clams), and for sea urchins for which no data about lipophilic toxins have been reported before. Moreover, we have compared the method performance under alkaline conditions using two quantification strategies: the external standard calibration (EXS) and the matrix-matched standard calibration (MMS). Alkaline conditions were the only scenario that allowed detection windows with polarity switching in a 3200 QTrap mass spectrometer, thus the analysis of all toxins can be accomplished in a single run, increasing sample throughput. The limits of quantification under alkaline conditions met the validation requirements established by the EURLMB for all toxins and matrices, while the remaining conditions failed in some cases. The accuracy of the method and the matrix effects where generally dependent on the mobile phases and the seafood species. The MMS had a moderate positive impact on method accuracy for crude extracts, but it showed poor trueness for seafood species other than mussels when analyzing hydrolyzed extracts. Alkaline conditions with EXS and recovery correction for OA were selected as the most proper conditions in the context of our laboratory. This comparative study can help other laboratories to choose the best conditions for the implementation of LC-MS/MS according to their own necessities.
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One of the key emphases of these three essays is to provide practical managerial insight. However, good practical insight, can only be created by grounding it firmly on theoretical and empirical research. Practical experience-based understanding without theoretical grounding remains tacit and cannot be easily disseminated. Theoretical understanding without links to real life remains sterile. My studies aim to increase the understanding of how radical innovation could be generated at large established firms and how it can have an impact on business performance as most businesses pursue innovation with one prime objective: value creation. My studies focus on large established firms with sales revenue exceeding USD $ 1 billion. Usually large established firms cannot rely on informal ways of management, as these firms tend to be multinational businesses operating with subsidiaries, offices, or production facilities in more than one country. I. Internal and External Determinants of Corporate Venture Capital Investment The goal of this chapter is to focus on CVC as one of the mechanisms available for established firms to source new ideas that can be exploited. We explore the internal and external determinants under which established firms engage in CVC to source new knowledge through investment in startups. We attempt to make scholars and managers aware of the forces that influence CVC activity by providing findings and insights to facilitate the strategic management of CVC. There are research opportunities to further understand the CVC phenomenon. Why do companies engage in CVC? What motivates them to continue "playing the game" and keep their active CVC investment status. The study examines CVC investment activity, and the importance of understanding the influential factors that make a firm decide to engage in CVC. The main question is: How do established firms' CVC programs adapt to changing internal conditions and external environments. Adaptation typically involves learning from exploratory endeavors, which enable companies to transform the ways they compete (Guth & Ginsberg, 1990). Our study extends the current stream of research on CVC. It aims to contribute to the literature by providing an extensive comparison of internal and external determinants leading to CVC investment activity. To our knowledge, this is the first study to examine the influence of internal and external determinants on CVC activity throughout specific expansion and contraction periods determined by structural breaks occurring between 1985 to 2008. Our econometric analysis indicates a strong and significant positive association between CVC activity and R&D, cash flow availability and environmental financial market conditions, as well as a significant negative association between sales growth and the decision to engage into CVC. The analysis of this study reveals that CVC investment is highly volatile, as demonstrated by dramatic fluctuations in CVC investment activity over the past decades. When analyzing the overall cyclical CVC period from 1985 to 2008 the results of our study suggest that CVC activity has a pattern influenced by financial factors such as the level of R&D, free cash flow, lack of sales growth, and external conditions of the economy, with the NASDAQ price index as the most significant variable influencing CVC during this period. II. Contribution of CVC and its Interaction with R&D to Value Creation The second essay takes into account the demands of corporate executives and shareholders regarding business performance and value creation justifications for investments in innovation. Billions of dollars are invested in CVC and R&D. However there is little evidence that CVC and its interaction with R&D create value. Firms operating in dynamic business sectors seek to innovate to create the value demanded by changing market conditions, consumer preferences, and competitive offerings. Consequently, firms operating in such business sectors put a premium on finding new, sustainable and competitive value propositions. CVC and R&D can help them in this challenge. Dushnitsky and Lenox (2006) presented evidence that CVC investment is associated with value creation. However, studies have shown that the most innovative firms do not necessarily benefit from innovation. For instance Oyon (2007) indicated that between 1995 and 2005 the most innovative automotive companies did not obtain adequate rewards for shareholders. The interaction between CVC and R&D has generated much debate in the CVC literature. Some researchers see them as substitutes suggesting that firms have to choose between CVC and R&D (Hellmann, 2002), while others expect them to be complementary (Chesbrough & Tucci, 2004). This study explores the interaction that CVC and R&D have on value creation. This essay examines the impact of CVC and R&D on value creation over sixteen years across six business sectors and different geographical regions. Our findings suggest that the effect of CVC and its interaction with R&D on value creation is positive and significant. In dynamic business sectors technologies rapidly relinquish obsolete, consequently firms operating in such business sectors need to continuously develop new sources of value creation (Eisenhardt & Martin, 2000; Qualls, Olshavsky, & Michaels, 1981). We conclude that in order to impact value creation, firms operating in business sectors such as Engineering & Business Services, and Information Communication & Technology ought to consider CVC as a vital element of their innovation strategy. Moreover, regarding the CVC and R&D interaction effect, our findings suggest that R&D and CVC are complementary to value creation hence firms in certain business sectors can be better off supporting both R&D and CVC simultaneously to increase the probability of generating value creation. III. MCS and Organizational Structures for Radical Innovation Incremental innovation is necessary for continuous improvement but it does not provide a sustainable permanent source of competitiveness (Cooper, 2003). On the other hand, radical innovation pursuing new technologies and new market frontiers can generate new platforms for growth providing firms with competitive advantages and high economic margin rents (Duchesneau et al., 1979; Markides & Geroski, 2005; O'Connor & DeMartino, 2006; Utterback, 1994). Interestingly, not all companies distinguish between incremental and radical innovation, and more importantly firms that manage innovation through a one-sizefits- all process can almost guarantee a sub-optimization of certain systems and resources (Davila et al., 2006). Moreover, we conducted research on the utilization of MCS along with radical innovation and flexible organizational structures as these have been associated with firm growth (Cooper, 2003; Davila & Foster, 2005, 2007; Markides & Geroski, 2005; O'Connor & DeMartino, 2006). Davila et al. (2009) identified research opportunities for innovation management and provided a list of pending issues: How do companies manage the process of radical and incremental innovation? What are the performance measures companies use to manage radical ideas and how do they select them? The fundamental objective of this paper is to address the following research question: What are the processes, MCS, and organizational structures for generating radical innovation? Moreover, in recent years, research on innovation management has been conducted mainly at either the firm level (Birkinshaw, Hamel, & Mol, 2008a) or at the project level examining appropriate management techniques associated with high levels of uncertainty (Burgelman & Sayles, 1988; Dougherty & Heller, 1994; Jelinek & Schoonhoven, 1993; Kanter, North, Bernstein, & Williamson, 1990; Leifer et al., 2000). Therefore, we embarked on a novel process-related research framework to observe the process stages, MCS, and organizational structures that can generate radical innovation. This article is based on a case study at Alcan Engineered Products, a division of a multinational company provider of lightweight material solutions. Our observations suggest that incremental and radical innovation should be managed through different processes, MCS and organizational structures that ought to be activated and adapted contingent to the type of innovation that is being pursued (i.e. incremental or radical innovation). More importantly, we conclude that radical can be generated in a systematic way through enablers such as processes, MCS, and organizational structures. This is in line with the findings of Jelinek and Schoonhoven (1993) and Davila et al. (2006; 2007) who show that innovative firms have institutionalized mechanisms, arguing that radical innovation cannot occur in an organic environment where flexibility and consensus are the main managerial mechanisms. They rather argue that radical innovation requires a clear organizational structure and formal MCS.
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Members of the ENaC/degenerin family of ion channels include the epithelial sodium channel (ENaC), acid-sensing ion channels (ASICs) and the nematode Caenorhabditis elegans degenerins. These channels are activated by a variety of stimuli such as ligands (ASICs) and mechanical forces (degenerins), or otherwise are constitutively active (ENaC). Despite their functional heterogeneity, these channels might share common basic mechanisms for gating. Mutations of a conserved residue in the extracellular loop, namely the 'degenerin site' activate all members of the ENaC/degenerin family. Chemical modification of a cysteine introduced in the degenerin site of rat ENaC (betaS518C) by the sulfhydryl reagents MTSET or MTSEA, results in a approximately 3-fold increase in the open probability. This effect is due to an 8-fold shortening of channel closed times and an increase in the number of long openings. In contrast to the intracellular gating domain in the N-terminus which is critical for channel opening, the intact extracellular degenerin site is necessary for normal channel closing, as illustrated by our observation that modification of betaS518C destabilises the channel closed state. The modification by the sulfhydryl reagents is state- and size-dependent consistent with a conformational change of the degenerin site during channel opening and closing. We propose that the intracellular and extracellular modulatory sites act on a common channel gate and control the activity of ENaC at the cell surface.
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The indication for pulmonary artery banding is currently limited by several factors. Previous attempts have failed to produce adjustable pulmonary artery banding with reliable external regulation. An implantable, telemetrically controlled, battery-free device (FloWatch) developed by EndoArt SA, a medical company established in Lausanne, Switzerland, for externally adjustable pulmonary artery banding was evaluated on minipigs and proved to be effective for up to 6 months. The first human implant was performed on a girl with complete atrioventricular septal defect with unbalanced ventricles, large patent ductus arteriosus and pulmonary hypertension. At one month of age she underwent closure of the patent ductus arteriosus and FloWatch implantation around the pulmonary artery through conventional left thoracotomy. The surgical procedure was rapid and uneventful. During the entire postoperative period bedside adjustments (narrowing or release of pulmonary artery banding with echocardiographic assessment) were repeatedly required to maintain an adequate pressure gradient. The early clinical results demonstrated the clinical benefits of unlimited external telemetric adjustments. The next step will be a multi-centre clinical trial to confirm the early results and adapt therapeutic strategies to this promising technology.
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BACKGROUND: To determine the outcome of patients with brain metastasis (BM) from lung cancer treated with an external beam radiotherapy boost (RTB) after whole brain radiotherapy (WBRT). METHODS: A total of 53 BM patients with lung cancer were treated sequentially with WBRT and RTB between 1996 and 2008 according to our institutional protocol. Mean age was 58.8 years. The median KPS was 90. Median recursive partitioning analysis (RPA) and graded prognostic assessment (GPA) grouping were 2 and 2.5, respectively. Surgery was performed on 38 (71%) patients. The median number of BM was 1 (range, 1-3). Median WBRT and RTB combined dose was 39 Gy (range, 37.5-54). Median follow-up was 12.0 months. RESULTS: During the period of follow-up, 37 (70%) patients died. The median overall survival (OS) was 14.5 months. Only 13 patients failed in the brain. The majority of patients (n = 29) failed distantly. The 1-year OS, -local control, extracranial failure rates were 61.2%, 75.2% and 60.8%, respectively. On univariate analysis, improved OS was found to be significantly associated with total dose (< or = 39 Gy vs. > 39 Gy; p < 0.01), age < 65 (p < 0.01), absence of extracranial metastasis (p < 0.01), GPA > or = 2.5 (p = 0.01), KPS > or = 90 (p = 0.01), and RPA < 2 (p = 0.04). On multivariate analysis, total dose (p < 0.01) and the absence of extracranial metastasis (p = 0.03) retained statistical significance. CONCLUSIONS: The majority of lung cancer patients treated with WBRT and RTB progressed extracranially. There might be a subgroup of younger patients with good performance status and no extracranial disease who may benefit from dose escalation after WBRT to the metastatic site.
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L’aplicació de tècniques respiromètriques és de recent innovació dins l’estudi dels tractaments d’aigües residuals. Aquest conjunt de tècniques ens permeten analitzar dos processos importants dins una planta de tractament biològic: el creixement de la biomassa i el consum del substrat. Això fa que siguin una eina amb gran potencial en l’avaluació dels sistemes de tractament biològic d’aigües residuals. L’objectiu principal d’aquest treball es la realització d’una aplicació capaç de controlar el funcionament de 6 respiròmetres, gestionant el procés del mostreig de les respirometries i l’anàlisi de les dades obtingudes, per obtenir el substrat ràpidament biodegradable (Ss) per a mostres d’aigua residual, i la taxa màxima de creixement específic per a mostres de compost. L’aplicació s’ha desenvolupat sobre l’entorn Microsoft Access, on s’integren la base de dades amb les mostres i els resultats de les respirometries, i els formularis de control que ens permeten gestionar i controlar els processos de mostreig i anàlisi. L’aplicació es comunica amb els sensors i actuadors dels respiròmetres a través del control ActiveX, ADS-OCX, subministrat per TwinCAT, que ens permet capturar les lectures dels sensors i controlar el funcionament dels actuadors. Aquests elements estan connectats a mòduls descentralitzats d’entrades i sortides, comunicats mitjançant el bus Ethernet amb el PC-Industrial, on s’executa l’aplicació. Un cop finalitzada l’aplicació, aquesta controla correctament el mostreig de les respirometries, registrant les lectures de les sondes a la base de dades i controlant l’activació de les vàlvules del respiròmetre. Partint de les mostres obtingudes, o de respirometries externes, importades des de Microsoft Excel, s’ha comprovat el correcte funcionament en el càlcul del substrat ràpidament biodegradable (Ss) i la taxa màxima de creixement específic. Amb l’aplicació desenvolupada, s’ha comprovat el funcionament i les possibilitats que ens ofereix TwinCAT alhora de controlar mòduls d’entrades i sortides, així com la seva comunicació amb aplicacions com Microsoft Access. Això pot afavorir a la utilització d’aquest tipus de tecnologia, per aplicacions futures.
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Regional data on wages for the Spanish economy show that workers who live in developed regions earn more than workers in other regions.Literature on external economies provides a possible explanation of why firms do not move from these regions to others where wages are lower. Previous studies for the Spanish case use aggregated sectoral data to explain in terms of external economies why average wages are different across regions. The originalcontribution of this paper consists of using individual data to detect the existenceand nature of external economies as an explanatory cause of territorial wagedifferences. With this aim, we have used individual data from the EPF 1990-91(INE). This information permits us to control the influence of individual and jobcharacteristics on wages to, first, detect the existence of external economies and,second, to test alternative explanations of their presence. The empirical evidenceobtained confirms the relevance of territorial external economies and their influence on wages, as a result of improvements in the productive efficiency of the firm. In concrete terms, the more relevant external economies are associatedwith the regional human capital stock and geographical productive specialisation
Resumo:
Regional data on wages for the Spanish economy show that workers who live in developed regions earn more than workers in other regions.Literature on external economies provides a possible explanation of why firms do not move from these regions to others where wages are lower. Previous studies for the Spanish case use aggregated sectoral data to explain in terms of external economies why average wages are different across regions. The originalcontribution of this paper consists of using individual data to detect the existenceand nature of external economies as an explanatory cause of territorial wagedifferences. With this aim, we have used individual data from the EPF 1990-91(INE). This information permits us to control the influence of individual and jobcharacteristics on wages to, first, detect the existence of external economies and,second, to test alternative explanations of their presence. The empirical evidenceobtained confirms the relevance of territorial external economies and their influence on wages, as a result of improvements in the productive efficiency of the firm. In concrete terms, the more relevant external economies are associatedwith the regional human capital stock and geographical productive specialisation
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We study the effects of external noise in a one-dimensional model of front propagation. Noise is introduced through the fluctuations of a control parameter leading to a multiplicative stochastic partial differential equation. Analytical and numerical results for the front shape and velocity are presented. The linear-marginal-stability theory is found to increase its range of validity in the presence of external noise. As a consequence noise can stabilize fronts not allowed by the deterministic equation.