936 resultados para Hold-up problem
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In this paper a genetic algorithm (GA) is applied on Maximum Betweennes Problem (MBP). The maximum of the objective function is obtained by finding a permutation which satisfies a maximal number of betweenness constraints. Every permutation considered is genetically coded with an integer representation. Standard operators are used in the GA. Instances in the experimental results are randomly generated. For smaller dimensions, optimal solutions of MBP are obtained by total enumeration. For those instances, the GA reached all optimal solutions except one. The GA also obtained results for larger instances of up to 50 elements and 1000 triples. The running time of execution and finding optimal results is quite short.
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Computing the similarity between two protein structures is a crucial task in molecular biology, and has been extensively investigated. Many protein structure comparison methods can be modeled as maximum weighted clique problems in specific k-partite graphs, referred here as alignment graphs. In this paper we present both a new integer programming formulation for solving such clique problems and a dedicated branch and bound algorithm for solving the maximum cardinality clique problem. Both approaches have been integrated in VAST, a software for aligning protein 3D structures largely used in the National Center for Biotechnology Information, an original clique solver which uses the well known Bron and Kerbosch algorithm (BK). Our computational results on real protein alignment instances show that our branch and bound algorithm is up to 116 times faster than BK.
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In this paper the low autocorrelation binary sequence problem (LABSP) is modeled as a mixed integer quadratic programming (MIQP) problem and proof of the model’s validity is given. Since the MIQP model is semidefinite, general optimization solvers can be used, and converge in a finite number of iterations. The experimental results show that IQP solvers, based on this MIQP formulation, are capable of optimally solving general/skew-symmetric LABSP instances of up to 30/51 elements in a moderate time. ACM Computing Classification System (1998): G.1.6, I.2.8.
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Even simple hybrid automata like the classic bouncing ball can exhibit Zeno behavior. The existence of this type of behavior has so far forced a large class of simulators to either ignore some events or risk looping indefinitely. This in turn forces modelers to either insert ad-hoc restrictions to circumvent Zeno behavior or to abandon hybrid automata. To address this problem, we take a fresh look at event detection and localization. A key insight that emerges from this investigation is that an enclosure for a given time interval can be valid independent of the occurrence of a given event. Such an event can then even occur an unbounded number of times. This insight makes it possible to handle some types of Zeno behavior. If the post-Zeno state is defined explicitly in the given model of the hybrid automaton, the computed enclosure covers the corresponding trajectory that starts from the Zeno point through a restarted evolution.
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Here we report on a potential catalytic process for efficient clean-up of plastic pollution in waters, such as the Great Pacific Garbage Patch (CPGP). Detailed catalytic mechanisms of RuO2 during supercritical water gasification of common polyolefin plastics including low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP) and polystyrene (PP), have been investigated in a batch reactor at 450 °C, 60 min. All four plastics gave very high carbon gasification efficiencies (CGE) and hydrogen gasification efficiencies (HGE). Methane was the highest gas component, with a yield of up to 37 mol kg−1LDPE using the 20 wt% RuO2 catalyst. Evaluation of the gas yields, CGE and HGE revealed that the conversion of PS involved thermal degradation, steam reforming and methanation; whereas hydrogenolysis was a possible additional mechanism during the conversion of aliphatic plastics. The process has the benefits of producing a clean-pressurized methane-rich fuel gas as well as cleaning up hydrocarbons-polluted waters.
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A szerző arra a kérdésre keresi a választ, hogyan alakulhat ki látványos szakadék az egyéni cselekvések iránya és azok együttes hatása között. A szándékok és tettek hatását felülírhatja a társadalmi gazdasági tényezőkből adódó tehetetlenség: a kritikus tömeg hiánya, szervezeti-infrastrukturális tényezők, kompenzációs hatások, egymás hatását kioltó cselekvések. A szerző a környezettudatosság és az ökológiai lábnyom példáján - ezerfős reprezentatív felmérésre alapozva - mutatja be, hogy az önkéntességre alapozó megközelítés sokszor túlbecsüli a fogyasztó - társadalmi-gazdasági tényezők által korlátozott - lehetőségeit és szuverenitását. _____ Behaviour impact gaps are demonstrably present in everyday life. It is increasingly found that environmental awareness in individuals fails to lead to reductions in the ecological footprint. Intensive agricultural practice reduces biodiversity in the EU even in areas where massive agri-environmental grant schemes are available and applied. Labour market training programmes do not necessarily facilitate job-finding for underprivileged segments of the society. So individual efforts may not add up or induce the expected effect. This outcome appears even for programmes that are successful in attaining the required behavioural change in a target group. The impact of attitudes and individual acts may be wiped out by structural and economic lock-ins such as trade-offs made for the gains, lack of a critical mass of actions, infrastructural deficiencies, or interfering acts of economic actors. The discrepancy between environmental awareness and ecological footprint is used to point out how awareness-raising programmes may miss their targets by overestimating the sovereignty and capabilities of consumers. Consumers are unwillingly locked into unsustainable practices and cannot be moved from that position unless economic and structural premises are also changed.
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Armed violence in Paraguay is not a recent phenomenon. During the second half of the XX Century, Paraguay saw the rise of a larger number of underground, revolutionary movements that sought the overthrow of the Alfredo Stroessner’s (1954-1989) government. From among those movements emerged the Partido Patria Libre (or, Free Fatherland, also known for its acronym PPL), made up of a two branches: one legal and the other one, operational. The latter was based on people’s power, as represented by “Ejército del Pueblo Paraguayo” (or, the Paraguayan People’s Army, with acronym EPP). After EPP broke with PPL in March 2008, this Marxist-oriented revolutionary project, which was apparently oriented to put an end to the social, political and economic inequalities in Paraguay, began to carry out markedly criminal activities, which included bank robberies, kidnappings, assassinations, terrorist attacks and armed confrontations. Its strategies and modus operandi utilized by the Armed Revolutionary Forces of Colombia (FARC). Paraguay features a farm sector in a state of crisis, in which cattle-ranchers, peasants and agro-exporting companies live in a constant strife. The Paraguayan Departments that are the most affected by this situation are Concepciόn, San Pedro, Canindeyú y Caazapá, which also suffer from a weak government presence. This deficiency has made these departments ripe for drug-trafficking activity by Brazilian groups such as Primer Comando Capital (i.e., First Capital command), also PCC and Comando Vermelho, (i.e., The Red Command). That is why many peasants, now recruited by EPP, have joined the drug-trafficking business and that, not only as marihuana growers but as “campanas” (i.e., early warning sentinels) for the organization. This helps shape their attitudes for their future involvement in all areas of drug-trafficking. Paraguayan society is the result of social inequity and inequality, such as those resulting from a lack of opportunity. Although Paraguay has successfully recovered from the last world economic crisis, economic growth, by itself, does not ensure an improvement in the quality of life. As long as such economic and social gaps persist and the government fails to enact the policies that would result in a more just society and toward EPP neutralization or containment, the latter is bound to grow stronger. In this context, the situation in Paraguay calls for more research into the EPP phenomenon. It would also seem necessary for Paraguay to promote an open national debate that includes all sectors of society in order to raise consciousness and to induce society to take actual steps to eliminate the EPP, as well as any other group that might arise in the immediate future. EPP has strong connections with the Frente Patriόtico Manuel Rodríguez in Chile and other armed groups and peasant movements in other countries of this region. Although most governments in the region are aware that the armed struggle is not a solution to current problems, it might be worth it to hold a regional debate about armed or insurgent groups in Latin American to seek common strategies and cooperation on dealing with them since the expansion of these armed groups is a problem for all.
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This study was conducted to determine the effects of the Changing Lives Program intervention on troubled adolescents' feelings of personal expressiveness, believed to be one domain of positive identity development. Forty-three intervention and twenty nonintervention comparison control participants were given a battery of pre-, post-, and follow-up assessments including the Personally Expressive Questionnaire (Waterman, 1995), which was used to derive participants' feelings of personal expressiveness scores. Using Repeated Measures Analysis of Multivariate Analysis (RMANOVA), a significant four-way interaction of Time X Condition X Gender X Ethnicity was found relative to the Control, Roy's Ɵ = .166, F(2,47) = 3.899, p < .027 indicating that intervention participants' feelings of personal expressiveness did increase significantly relative to the control group. Furthermore, the results suggest differential outcomes based on ethnicity, suggesting the need for future study with respect to specificity of effects and mechanisms of identity formation in differing ethnic subgroups.
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This dissertation will be marked by our proposal to hold a theoretical perspective to the classical mind-body problem, and more precisely for the defense of the idea that consciousness (or conscious mind) emerges from the interaction and integration relationships between body proper, brain and environment. This purpose will lead us to assume an alternative position with respect to the more traditional perspectives to the mind-body problem, ie an alternative perspective not only in relation to the dualistics forms of mind-body, but also in regards to the reductive physicalists, which usually reduces mind to brain. Aiming to support a position that both avoid the idea that mind and body are distinct substances and the theory that the brain explains the consciousness in its totality, we will dedicate an important part of this work to explain how the structure of consciousness depends significantly of the body proper and the bodily information mechanisms as well as the environment and the physiological mechanisms through which we place ourselves in space, in front of us and the other bodies (organic and inorganic). Given that the relationship between brain, body and environment involves different mental levels — from the most primitive and unconscious mental mechanisms until conscious and sophisticated levels — we will proceed to the task of assuming a model to explain in what sense these levels contribute to that our instincts and the most sophisticated dimensions of our mental life are part of the one and the same process, which is why we will structure our argument from the ideia that mind, self, and consciousness are the different hierarchical levels which make up the totality of our psychic life and therefore organic one. Imbued with this conceptual approach, we will advance to the focus of this work, namely the reasons that will lead us to give a prominent role to the body proper and the environment in the constitution of the conscious mind, or even the reasons that will lead us to defend the thesis according to which we are embodied and situated, as well as the reasons that will lead us to reject the theoretical positions that dichotomize man and world. In order to support the thesis that we are embodied and situated, and therefore with the purpose of overcoming the theoretical paradigms that dichotomize consciousness and world, we will turn out to the authors and the perspectives we believe to be more successful in this endeavor, including the phenomenological approaches to bodily self-consciousness, the enactivists perspectives and the researches dedicated to mapping the interaction and integration relationships between brain, body and environment. To achieve our goals, the dissertation will be divided into two chapters: the first chapter will emphasize in what way the structuring of consciousness depends on the body proper and the environment, while in the second chapter we will resort to the phenomenological dimensions of bodily self-consciousness, emphasizing the bodily information channels that provide us the immediate certainty, in a first person perspective, that the self is bodily in a non-metaphorical sense.
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This paper presents the summary of the key objectives, instrumentation and logistic details, goals, and initial scientific findings of the European Marie Curie Action SAPUSS project carried out in the western Mediterranean Basin (WMB) during September-October in autumn 2010. The key SAPUSS objective is to deduce aerosol source characteristics and to understand the atmospheric processes responsible for their generations and transformations - both horizontally and vertically in the Mediterranean urban environment. In order to achieve so, the unique approach of SAPUSS is the concurrent measurements of aerosols with multiple techniques occurring simultaneously in six monitoring sites around the city of Barcelona (NE Spain): a main road traffic site, two urban background sites, a regional background site and two urban tower sites (150 m and 545 m above sea level, 150 m and 80 m above ground, respectively). SAPUSS allows us to advance our knowledge sensibly of the atmospheric chemistry and physics of the urban Mediterranean environment. This is well achieved only because of both the three dimensional spatial scale and the high sampling time resolution used. During SAPUSS different meteorological regimes were encountered, including warm Saharan, cold Atlantic, wet European and stagnant regional ones. The different meteorology of such regimes is herein described. Additionally, we report the trends of the parameters regulated by air quality purposes (both gaseous and aerosol mass concentrations); and we also compare the six monitoring sites. High levels of traffic-related gaseous pollutants were measured at the urban ground level monitoring sites, whereas layers of tropospheric ozone were recorded at tower levels. Particularly, tower level night-time average ozone concentrations (80 +/- 25 mu g m(-3)) were up to double compared to ground level ones. The examination of the vertical profiles clearly shows the predominant influence of NOx on ozone concentrations, and a source of ozone aloft. Analysis of the particulate matter (PM) mass concentrations shows an enhancement of coarse particles (PM2.5-10) at the urban ground level (+64 %, average 11.7 mu g m(-3)) but of fine ones (PM1) at urban tower level (+28 %, average 14.4 mu g m(-3)). These results show complex dynamics of the size-resolved PM mass at both horizontal and vertical levels of the study area. Preliminary modelling findings reveal an underestimation of the fine accumulation aerosols. In summary, this paper lays the foundation of SAPUSS, an integrated study of relevance to many other similar urban Mediterranean coastal environment sites.
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Background: Rates of self-harm are high and have recently increased. This trend and the repetitive nature of self-harm pose a significant challenge to mental health services. Aims: To determine the efficacy of a structured group problem-solving skills training (PST) programme as an intervention approach for self-harm in addition to treatment as usual (TAU) as offered by mental health services. Method: A total of 433 participants (aged 18-64 years) were randomly assigned to TAU plus PST or TAU alone. Assessments were carried out at baseline and at 6-week and 6-month follow-up and repeated hospital-treated self-harm was ascertained at 12-month follow-up. Results: The treatment groups did not differ in rates of repeated self-harm at 6-week, 6-month and 12-month follow-up. Both treatment groups showed significant improvements in psychological and social functioning at follow-up. Only one measure (needing and receiving practical help from those closest to them) showed a positive treatment effect at 6-week (P = 0.004) and 6-month (P = 0.01) follow-up. Repetition was not associated with waiting time in the PST group. Conclusions: This brief intervention for self-harm is no more effective than treatment as usual. Further work is required to establish whether a modified, more intensive programme delivered sooner after the index episode would be effective.
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The purpose of this research is to examine the use of a mock-up review process in interior design projects to better understand the implications of using such a process within the standard professional practice model. The research consisted of interviewing design professionals who utilize mock-ups as part of their standard of practice. These interviews were centered around two groups - those working in shipbuilding, where mock-ups have a long history, and those working in land-based projects, where mock-up use is rare. Analysis of the interviews indicated a positive relationship between mock-up use and collaboration, innovation, and problem solving. The interviews also brought to light concerns on behalf of all the professionals surveyed about the current practice model in land-based building design and construction projects within the United States. The positive relationships shown in the thesis support further research to explore how mock-ups can be best utilized in interior design.
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Conventional taught learning practices often experience difficulties in keeping students motivated and engaged. Video games, however, are very successful at sustaining high levels of motivation and engagement through a set of tasks for hours without apparent loss of focus. In addition, gamers solve complex problems within a gaming environment without feeling fatigue or frustration, as they would typically do with a comparable learning task. Based on this notion, the academic community is keen on exploring methods that can deliver deep learner engagement and has shown increased interest in adopting gamification – the integration of gaming elements, mechanics, and frameworks into non-game situations and scenarios – as a means to increase student engagement and improve information retention. Its effectiveness when applied to education has been debatable though, as attempts have generally been restricted to one-dimensional approaches such as transposing a trivial reward system onto existing teaching materials and/or assessments. Nevertheless, a gamified, multi-dimensional, problem-based learning approach can yield improved results even when applied to a very complex and traditionally dry task like the teaching of computer programming, as shown in this paper. The presented quasi-experimental study used a combination of instructor feedback, real time sequence of scored quizzes, and live coding to deliver a fully interactive learning experience. More specifically, the “Kahoot!” Classroom Response System (CRS), the classroom version of the TV game show “Who Wants To Be A Millionaire?”, and Codecademy’s interactive platform formed the basis for a learning model which was applied to an entry-level Python programming course. Students were thus allowed to experience multiple interlocking methods similar to those commonly found in a top quality game experience. To assess gamification’s impact on learning, empirical data from the gamified group were compared to those from a control group who was taught through a traditional learning approach, similar to the one which had been used during previous cohorts. Despite this being a relatively small-scale study, the results and findings for a number of key metrics, including attendance, downloading of course material, and final grades, were encouraging and proved that the gamified approach was motivating and enriching for both students and instructors.
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The present study was aimed at assessing the experience of a single referral center with recurrent varicose veins of the legs (RVL) over the period 1993-2008. Among a total of 846 procedures for Leg Varices (LV), 74 procedures were for RVL (8.7%). The causes of recurrence were classified as classic: insufficient crossectomy (13); incompetent perforating veins (13); reticular phlebectasia (22); small saphenous vein insufficiency (9); accessory saphenous veins (4); and particular: post-hemodynamic treatment (5); incomplete stripping (1); Sapheno-Femoral Junction (SFJ) vascularization (5); post-thermal ablation (2). For the “classic” RVL the treatment consisted essentially of completing the previous treatment, both if the problem was linked to an insufficient earlier treatment and if it was due to a later onset. The most common cause in our series was reticular phlebectasia; when the simple sclerosing injections are not sufficient, this was treated by phlebectomy according to Mueller. The “particular” cases classified as 1, 2 and 4 were also treated by completing the traditional stripping procedure (+ crossectomy if this had not been done previously), considered to be the gold standard. In the presence of a SFJ neo-vascularization, with or without cavernoma, approximately 5 cm of femoral vein were explored, the afferent vessels ligated and, if cavernoma was present, it was removed. Although inguinal neo-angiogenesis is a possible mechanism, some doubt can be raised as to its importance as a primary factor in causing recurrent varicose veins, rather than their being due to a preexisting vein left in situ because it was ignored, regarded as insignificant, or poorly evident. In conclusion, we stress that LV is a progressive disease, so the treatment is unlikely to be confined to a single procedure. It is important to plan adequate monitoring during follow-up, and to be ready to reoperate when new problems present that, if left, could lead the patient to doubt the validity and efficacy of the original treatment.
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Objectives: Obesity during adolescence is an increasing health problem in industrial countries. The comorbidities associated with obesity include important metabolic diseases. Methods: To analyze the effect of a weight-loss program, we recruited 12 obese, male adolescents before entering this program. We determined body weight measures at baseline, 6-week and 36-month follow-up. Also, the long-term changes of blood pressure, HbAlc, and CRP were evaluated. Twenty healthy age-matched adolescents served as controls. Results: Within the intervention group ((body mass index [BMI, kg/m²] > 95th percentile for age and sex, age 13-17 years) the BMI and BMI-standard deviation score [SDS] were significantly reduced in the 6-week follow-up after completing the weight loss program. However, the significant weight-reduction effect was not persistent until the 36-month follow-up. Conclusion: The 6-week weight-loss program had beneficial short-term effects on body weight, BMI, and BMI-SDS in obese adolescents, but these effects could not be maintained until the 36-month follow-up.