932 resultados para Markov chains. Convergence. Evolutionary Strategy. Large Deviations
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This symposium describes a multi-dimensional strategy to examine fidelity of implementation in an authentic school district context. An existing large-district peer mentoring program provides an example. The presentation will address development of a logic model to articulate a theory of change; collaborative creation of a data set aligned with essential concepts and research questions; identification of independent, dependent, and covariate variables; issues related to use of big data that include conditioning and transformation of data prior to analysis; operationalization of a strategy to capture fidelity of implementation data from all stakeholders; and ways in which fidelity indicators might be used.
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This paper is concerned with strategic optimization of a typical industrial chemical supply chain, which involves a material purchase and transportation network, several manufacturing plants with on-site material and product inventories, a product transportation network and several regional markets. In order to address large uncertainties in customer demands at the different regional markets, a novel robust scenario formulation, which has been developed by the authors recently, is tailored and applied for the strategic optimization. Case study results show that the robust scenario formulation works well for this real industrial supply chain system, and it outperforms the deterministic formulation and the classical scenario-based stochastic programming formulation by generating better expected economic performance and solutions that are guaranteed to be feasible for all uncertainty realizations. The robust scenario problem exhibits a decomposable structure that can be taken advantage of by Benders decomposition for efficient solution, so the application of Benders decomposition to the solution of the strategic optimization is also discussed. The case study results show that Benders decomposition can reduce the solution time by almost an order of magnitude when the number of scenarios in the problem is large.
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We study the nonequilibrium dynamics of the linear to zigzag structural phase transition exhibited by an ion chain confined in a trap with periodic boundary conditions. The transition is driven by reducing the transverse confinement at a finite quench rate, which can be accurately controlled. This results in the formation of zigzag domains oriented along different transverse planes. The twists between different domains can be stabilized by the topology of the trap and under laser cooling the system has a chance to relax to a helical chain with nonzero winding number. Molecular dynamics simulations are used to obtain a large sample of possible trajectories for different quench rates. The scaling of the average winding number with different quench rates is compared to the prediction of the Kibble-Zurek theory, and a good quantitative agreement is found.
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The pathogenesis of diffuse large B-cell lymphoma (DLBCL) remains partially unknown. The analysis of the B-cell receptor of the malignant cells could contribute to a better understanding of the DLBCL biology. We studied the molecular features of the immunoglobulin heavy chain (IGH) rearrangements in 165 patients diagnosed with DLBCL not otherwise specified. Clonal IGH rearrangements were amplified according to the BIOMED-2 protocol and PCR products were sequenced directly. We also analyzed the criteria for stereotyped patterns in all complete IGHV-IGHD-IGHJ (V-D-J) sequences. Complete V-D-J rearrangements were identified in 130 of 165 patients. Most cases (89%) were highly mutated, but 12 sequences were truly unmutated or minimally mutated. Three genes, IGHV4-34, IGHV3-23, and IGHV4-39, accounted for one third of the whole cohort, including an overrepresentation of IGHV4-34 (15.5% overall). Interestingly, all IGHV4-34 rearrangements and all unmutated sequences belonged to the nongerminal center B-cell-like (non-GCB) subtype. Overall, we found three cases following the current criteria for stereotyped heavy chain VH CDR3 sequences, two of them belonging to subsets previously described in CLL. IGHV gene repertoire is remarkably biased, implying an antigen-driven origin in DLBCL. The particular features in the sequence of the immunoglobulins suggest the existence of particular subgroups within the non-GCB subtype.
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Wind generation in highly interconnected power networks creates local and centralised stability issues based on their proximity to conventional synchronous generators and load centres. This paper examines the large disturbance stability issues (i.e. rotor angle and voltage stability) in power networks with geographically distributed wind resources in the context of a number of dispatch scenarios based on profiles of historical wind generation for a real power network. Stability issues have been analysed using novel stability indices developed from dynamic characteristics of wind generation. The results of this study show that localised stability issues worsen when significant penetration of both conventional and wind generation is present due to their non-complementary characteristics. In contrast, network stability improves when either high penetration of wind and synchronous generation is present in the network. Therefore, network regions can be clustered into two distinct stability groups (i.e. superior stability and inferior stability regions). Network stability improves when a voltage control strategy is implemented at wind farms, however both stability clusters remain unchanged irrespective of change in the control strategy. Moreover, this study has shown that the enhanced fault ride-through (FRT) strategy for wind farms can improve both voltage and rotor angle stability locally, but only a marginal improvement is evident in neighbouring regions.
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The cysteine protease cathepsin C (CatC) activates granule-associated proinflammatory serine proteases in hematopoietic precursor cells. Its early inhibition in the bone marrow is regarded as a new therapeutic strategy for treating proteolysis-driven chronic inflammatory diseases, but its complete inhibition is elusive in vivo Controlling the activity of CatC may be achieved by directly inhibiting its activity with a specific inhibitor or/and by preventing its maturation. We have investigated immunochemically and kinetically the occurrence of CatC and its proform in human hematopoietic precursor cells and in differentiated mature immune cells in lung secretions. The maturation of proCatC obeys a multistep mechanism that can be entirely managed by CatS in neutrophilic precursor cells. CatS inhibition by a cell-permeable inhibitor abrogated the release of the heavy and light chains from proCatC and blocked ∼80% of CatC activity. Under these conditions the activity of neutrophil serine proteases, however, was not abolished in precursor cell cultures. In patients with neutrophilic lung inflammation, mature CatC is found in large amounts in sputa. It is secreted by activated neutrophils as confirmed through lipopolysaccharide administration in a nonhuman primate model. CatS inhibitors currently in clinical trials are expected to decrease the activity of neutrophilic CatC without affecting those of elastase-like serine proteases.
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The sudden change in environmental munificence level in the construction sector
during the period 2007 – 2015 provides a natural experiment to investigate strategic
and operating actions of firms, particularly during an environmental jolt. Statistics on
business failures corroborate that neither academics nor practitioners have succeeded
in guiding strategic action during periods of environmental jolt. Despite the recent
increase of turnaround research in the general management domain, its use in the
construction management realm remains underexplored. To address this research
gap, five exploratory case studies of an ongoing PhD study were used to examine the
turnaround strategies of construction contractors during a period of economic
contraction and growth. The findings show that, although retrenchment is often
considered to be a short-term strategy, this is clearly not the case; with the majority of
contractors maintaining the strategy for 6-7 years. During the same period,
internationalization became critical, with the turnaround process shifting towards
strategic reorientation that altered the firms' market domain. The case studies further
suggest that strategic and operational actions resonate quite well with contemporary
practice-based approaches to strategy making. The findings provide valuable
assistance for construction contractors in dealing with organisational decline and in
developing a successful turnaround response.
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Thesis (Ph.D.)--University of Washington, 2016-08
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The objective is to analyze the relationship between risk and number of stocks of a portfolio for an individual investor when stocks are chosen by "naive strategy". For this, we carried out an experiment in which individuals select actions to reproduce this relationship. 126 participants were informed that the risk of first choice would be an asset average of all standard deviations of the portfolios consist of a single asset, and the same procedure should be used for portfolios composed of two, three and so on, up to 30 actions . They selected the assets they want in their portfolios without the support of a financial analysis. For comparison we also tested a hypothetical simulation of 126 investors who selected shares the same universe, through a random number generator. Thus, each real participant is compensated for random hypothetical investor facing the same opportunity. Patterns were observed in the portfolios of individual participants, characterizing the curves for the components of the samples. Because these groupings are somewhat arbitrary, it was used a more objective measure of behavior: a simple linear regression for each participant, in order to predict the variance of the portfolio depending on the number of assets. In addition, we conducted a pooled regression on all observations by analyzing cross-section. The result of pattern occurs on average but not for most individuals, many of which effectively "de-diversify" when adding seemingly random bonds. Furthermore, the results are slightly worse using a random number generator. This finding challenges the belief that only a small number of titles is necessary for diversification and shows that there is only applicable to a large sample. The implications are important since many individual investors holding few stocks in their portfolios
Resumo:
Decisions made and actions taken by individuals in the operations function impact the formation of a company’s manufacturing strategy (MS). Therefore, it is important that the MS is understood and agreed on by all employees, that is, strategic consensus among the individuals in the operations function is essential. This research contributes to the current body of knowledge by including a workers’ perspective on MS formation. It is the workers on the shop floor who bring the MS to life in the actual operations through their daily decisions and actions. The MS falls short if the priorities outlined do not materialise in practice as intended. The purpose of this research is to investigate how the individuals in the operations function perceive the MS in order to understand how these individuals are involved in the MS formation. The research is based on five studies, differing by evidence, as follows: one theoretical, three qualitative in the setting of small and medium-sized enterprises (SMEs), and one quantitative at a large company. Based on the findings presented in the six appended papers, the results show that empirically and conceptually, workers have been overlooked or given a passive role in the MS formation. Empirically, it is seen that workers and managers do not have a shared understanding of the underlying reasons for strategic priorities; hence, the level of strategic consensus is low. Furthermore, the level of strategic consensus varies among the different MS dimensions depending on their organisational level. Moreover, the empirical findings reveal that internal contextual factors influence the individuals’ perceptions of the MS and the possibilities for strategic consensus. Regarding the external context, the results show that major customers’ strategies influence the subcontractor SMEs’ MS formation. The usage of means of communication in the operations function has also shown to be of importance for how the MS is perceived. Conceptually, the findings indicate that the MS literature tends to treat individuals in the operations function in a deterministic manner; individuals on the shop floor are regarded as manufacturing resources. To ensure a successful MS formation process, where the patterns of the decisions made by the individuals in the operations function forms the MS, the view on human nature within the MS requires a more voluntaristic approach. This research suggests to view the MS formation as an iterative “patterning process” which builds on a reciprocal relationship between workers and managers. The introduction of the patterning process contributes to the research on MS formation by explaining the perception range within the hierarchical levels, by re-defining the hierarchical levels included in the MS formation and by detailing the activities in the MS formation.
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Background and problem – As a result of financial crises and the realization of a broader stakeholder network, recent decades have seen an increase in stakeholder demand for non- financial information in corporate reporting. This has led to a situation of information overload where separate financial and sustainability reports have developed in length and complexity interdependent of each other. Integrated reporting has been presented as a solution to this problematic situation. The question is whether the corporate world believe this to be the solution and if the development of corporate reporting is heading in this direction. Purpose - This thesis aims to examine and assess to what extent companies listed on the OMX Stockholm 30 (OMXS30), as per 2016-02-28, comply with the Strategic content element of the <IR> Framework and how this disclosure has developed since the framework’s pilot project and official release by using a self-constructed disclosure index based on its specific items. Methodology – The purpose was fulfilled through an analysis of 104 annual reports comprising 26 companies during the period of 2011-2014. The annual reports were assessed using a self-constructed disclosure index based on the <IR> Framework content element Strategy and Resource Allocation, where one point was given for each disclosed item. Analysis and conclusions – The study found that the OMXS30-listed companies to a large extent complies with the strategic content element of the <IR> Framework and that this compliance has seen a steady growth throughout the researched time span. There is still room for improvement however with a total average framework compliance of 84% for 2014. Although many items are being reported on, there are indications that companies generally miss out on the core values of Integrated reporting.
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A large class of computational problems are characterised by frequent synchronisation, and computational requirements which change as a function of time. When such a problem is solved on a message passing multiprocessor machine [5], the combination of these characteristics leads to system performance which deteriorate in time. As the communication performance of parallel hardware steadily improves so load balance becomes a dominant factor in obtaining high parallel efficiency. Performance can be improved with periodic redistribution of computational load; however, redistribution can sometimes be very costly. We study the issue of deciding when to invoke a global load re-balancing mechanism. Such a decision policy must actively weigh the costs of remapping against the performance benefits, and should be general enough to apply automatically to a wide range of computations. This paper discusses a generic strategy for Dynamic Load Balancing (DLB) in unstructured mesh computational mechanics applications. The strategy is intended to handle varying levels of load changes throughout the run. The major issues involved in a generic dynamic load balancing scheme will be investigated together with techniques to automate the implementation of a dynamic load balancing mechanism within the Computer Aided Parallelisation Tools (CAPTools) environment, which is a semi-automatic tool for parallelisation of mesh based FORTRAN codes.
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Purpose: The aims of this study were to compare angle of deviation, fusional vergence measurements and fusion reserve ratio between esophoria and exophoria. Methods: A cross-sectional study was performed in children with best-corrected visual acuity of 0.0 LogMAR in either eye, compensated heterophoria within 10 prism dioptres (PD), full ocular rotations, presence of fusional vergence and stereopsis (60 seconds of arc or better). Fusional amplitudes were compared between angle of deviation (2, 4, 6, 8 and 10 PD) in esophoria and exophoria. The fusion reserve ratio was calculated (to assess the effect of the underlying angle of deviation) as fusional convergence divided by prism alternating cover test measurements. Results: Two-hundred and eleven children (7.65±1.16 years) were recruited to this study. Exophoria was most common for near (n=181; 85.8%) and distance (n=20; 9.5%). Esophoria was present in 22 children for near (10.4%) and in 1 child for distance (0.5%). No significant differences were found between fusional amplitudes and angle of deviation for near (p>0.05). Children with exophoria of 10PD had a slight, but not, significant (p=0.264) increase in fusional convergence from 2PD (19.95±5.09) to 10PD (26.67±5.77). In esophoric children the variation of fusional convergence was smaller from 2P (25.00±0.00) to 10PD (22.50±3.54) and non significant (p=0.185). The fusion reserve ratio was significantly smaller in children with higher deviations (i.e. 10PD) for both esophoria (p=0.003) and exophoria (p>0.001). The fusion reserve ratio ranged between 12.50 (2PD) and 2.25±0.35 (10PD) for esophoria and between 9.98±2.55 (2PD) and 2.67±0.58 (10PD) for exophoria. Conclusions: Angle of deviation is not an efficient measure to predict fusional amplitudes. The fusion reserve ratio appears to be a better measurement to assess the effect of the underlying angle of deviation on fusional convergence. More studies are necessary to understand better the relationship between fusion amplitudes and angle of deviation.
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Ideas about the evolution of imperfect mimicry are reviewed. Their relevance to the colours patterns of hoverflies (Diptera, Syrphidae) are discussed in detail. Most if not all of the hoverflies labelled as mimetic actually are mimics. The apparently poor nature of their resemblance does not prevent them from obtaining at least some protection from suitably experienced birds. Mimicry is a dominant theme of this very large family of Diptera, with at least a quarter of all species in Europe being mimetic. Hoverfly mimics fall into three major groups according to their models, involving bumblebees, honeybees and social wasps. There are striking differences in the general levels of mimetic fidelity and relative abundances of the three groups, with accurate mimicry, low abundance and polymorphism characterizing the bumblebee mimics: more than half of all the species of bumblebee mimics are polymorphic. Mimics of social wasps tend to be poor mimics, have high relative abundance, and polymorphism is completely absent. Bumblebee models fall into a small number of Muellerian mimicry rings which are very different between the Palaearctic and Nearctic regions. Social wasps and associated models form one large Muellerian complex. Together with honeybees, these complexes probably form real clusters of forms as perceived by many birds. All three groups of syrphid mimics contain both good and poor mimics; some mimics are remarkably accurate, and have close morphological and behavioural resemblance. At least some apparently 'poor' mimetic resemblances may be much closer in birds' perception than we imagine, and more work needs to be done on this. Bumblebees are the least noxious and wasps the most noxious of the three main model groups. The basis of noxiousness is different, with bumblebees being classified as non-food, whereas honeybees and wasps are nasty-tasting and (rarely) stinging. The distribution of mimicry is exactly what would be expected from this ordering, with polymorphic and accurate forms being a key feature of mimics of the least noxious models, while highly noxious models have poor-quality mimicry. Even if the high abundance of many syrphid mimics relative to their models is a recent artefact of man-made environmental change, this does not preclude these species from being mimics. It seems unlikely that bird predation actually controls the populations of adult syrphids. Being rare relative to a model may have promoted or accelerated the evolution of perfect mimicry: theoretically this might account for the pattern of rare good mimics and abundant poor ones, but the idea is intrinsically unlikely. Many mimics seem to have hour-to-hour abundances related to those of their models, presumably as a result of behavioural convergence. We need to know much more about the psychology of birds as predators. There are at least four processes that need elucidating: (a) learning about the noxiousness of models; (b) the erasing of that learning through contact with mimics (extinction, or learned forgetting); (c) forgetting; (d) deliberate risk-taking and the physiological states that promote it. Johnston's (2002) model of the stabilization of imperfect mimicry by kin selection is unlikely to account for the colour patterns of hoverflies. Sherratt's (2002) model of the influence of multiple models potentially accounts for all the patterns of hoverfly mimicry, and is the most promising avenue for testing.
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The main thesis of this article is that the increasing recourse to the use of unmanned aerial systems in asymmetric warfare and the beginning routinization of U.S. drone operations represent part of an evolutionary change in the spatial ordering of global politics -- Using a heuristic framework based on actor-network theory, it is argued that practices of panoptic observation and selective airstrikes, being in need of legal justification, contribute to a reterritorialization of asymmetric conflicts -- Under a new normative spatial regime, a legal condition of state immaturity is constructed, which establishes a zone of conditional sovereignty subject to transnational aerial policing -- At the same time, this process is neither a deterministic result of the new technology nor a deliberate effect of policies to which drones are merely neutral instruments -- Rather, military technology and political decisions both form part of a long chain of action which has evolved under the specific circumstances of recent military interventions