The single machine earliness and tardiness scheduling problem: lower bounds and a branch-and-bound algorithm

This paper addresses the single machine scheduling problem with a common due date aiming to minimize earliness and tardiness penalties. Due to its complexity, most of the previous studies in the literature deal with this problem using heuristics and metaheuristics approaches. With the intention of contributing to the study of this problem, a branch-and-bound algorithm is proposed. Lower bounds and pruning rules that exploit properties of the problem are introduced. The proposed approach is examined through a computational comparative study with 280 problems involving different due date scenarios. In addition, the values of optimal solutions for small problems from a known benchmark are provided.

Some heuristic algorithms for total tardiness minimization in a flowshop with blocking

The flowshop scheduling problem with blocking in-process is addressed in this paper. In this environment, there are no buffers between successive machines: therefore intermediate queues of jobs waiting in the system for their next operations are not allowed. Heuristic approaches are proposed to minimize the total tardiness criterion. A constructive heuristic that explores specific characteristics of the problem is presented. Moreover, a GRASP-based heuristic is proposed and Coupled with a path relinking strategy to search for better outcomes. Computational tests are presented and the comparisons made with an adaptation of the NEH algorithm and with a branch-and-bound algorithm indicate that the new approaches are promising. (c) 2007 Elsevier Ltd. All rights reserved.

Effects of data characteristics on the results of reserve selection algorithms

We tested the effects of four data characteristics on the results of reserve selection algorithms. The data characteristics were nestedness of features (land types in this case), rarity of features, size variation of sites (potential reserves) and size of data sets (numbers of sites and features). We manipulated data sets to produce three levels, with replication, of each of these data characteristics while holding the other three characteristics constant. We then used an optimizing algorithm and three heuristic algorithms to select sites to solve several reservation problems. We measured efficiency as the number or total area of selected sites, indicating the relative cost of a reserve system. Higher nestedness increased the efficiency of all algorithms (reduced the total cost of new reserves). Higher rarity reduced the efficiency of all algorithms (increased the total cost of new reserves). More variation in site size increased the efficiency of all algorithms expressed in terms of total area of selected sites. We measured the suboptimality of heuristic algorithms as the percentage increase of their results over optimal (minimum possible) results. Suboptimality is a measure of the reliability of heuristics as indicative costing analyses. Higher rarity reduced the suboptimality of heuristics (increased their reliability) and there is some evidence that more size variation did the same for the total area of selected sites. We discuss the implications of these results for the use of reserve selection algorithms as indicative and real-world planning tools.

'You can criticise because you care': Identification, constructiveness, and the intergroup sensitivity effect

Group criticisms judged to be reasonable in the mouth of an ingroup member are aggressively rejected when they stem from an outgroup member (the intergroup sensitivity effect). Mediational analyses suggest that this phenomenon is underpinned by an attributional bias; criticisms from insiders are more likely to be perceived as being motivated for constructive reasons than are criticisms from outsiders, thus arousing lower levels of defensiveness. But what if group members were to receive information that called into question the ingroup critic's commitment to the group? For example, if the ingroup critic was known to be a low identifier with their group, or used language to suggest that they were psychologically distancing themselves from their group, we might expect that ingroup critics will be downgraded as strongly as outgroup critics. Furthermore, it might be possible for people to turn an outgroup criticism into an ingroup criticism by making salient their shared identity at the superordinate level. Three experiments are described that provide support for each of these propositions.

Evaluating the efficiency of fractional integration parameter estimators

This article deals with the efficiency of fractional integration parameter estimators. This study was based on Monte Carlo experiments involving simulated stochastic processes with integration orders in the range]-1,1[. The evaluated estimation methods were classified into two groups: heuristics and semiparametric/maximum likelihood (ML). The study revealed that the comparative efficiency of the estimators, measured by the lesser mean squared error, depends on the stationary/non-stationary and persistency/anti-persistency conditions of the series. The ML estimator was shown to be superior for stationary persistent processes; the wavelet spectrum-based estimators were better for non-stationary mean reversible and invertible anti-persistent processes; the weighted periodogram-based estimator was shown to be superior for non-invertible anti-persistent processes.

Systemic Model for Diagnosis of the Micro, Small and Medium Enterprises from Two Cities from the Countryside of the State of So Paulo in Brazil

This article presents a proposal of a systemic model composed for the micro and small companies (MSE) of the region of Ribeiro Preto and the agents which influenced their environment. The proposed model was based on Stafford Beer`s (Diagnosing the system for organizations. Chichester, Wiley, 1985) systemic methodologies VSM (Viable System Model) and on Werner Ulrich`s (1983) CSH (Critical Systems Heuristics). The VSM is a model for the diagnosis of the structure of an organization and of its flows of information through the application of the cybernetics concepts (Narvarte, In El Modelo del Sistema Viable-MSV: experiencias de su aplicacin en Chile. Proyecto Cerebro Colectivo del IAS, Santiago, 2001). On the other hand, CSH focus on the context of the social group applied to the systemic vision as a counterpoint to the organizational management view considered by the VSM. MSE of Ribeiro Preto and Sertozinho had been analyzed as organizations inserted in systems that relate and integrate with other systems concerning the public administration, entities of representation and promotion agencies. The research questions: which are the bonds of interaction among the subsystems in this process and who are the agents involved? The systemic approach not only diagnosed a social group, formed by MSE of Ribeiro Preto and Sertozinho, public authorities and support entities, but could also delineate answers that aimed the clarification of obscure questions generating financial assistance to the formularization of efficient actions for the development of this system.

Comparing predictions of extinction risk using models and subjective judgement

Models of population dynamics are commonly used to predict risks in ecology, particularly risks of population decline. There is often considerable uncertainty associated with these predictions. However, alternatives to predictions based on population models have not been assessed. We used simulation models of hypothetical species to generate the kinds of data that might typically be available to ecologists and then invited other researchers to predict risks of population declines using these data. The accuracy of the predictions was assessed by comparison with the forecasts of the original model. The researchers used either population models or subjective judgement to make their predictions. Predictions made using models were only slightly more accurate than subjective judgements of risk. However, predictions using models tended to be unbiased, while subjective judgements were biased towards over-estimation. Psychology literature suggests that the bias of subjective judgements is likely to vary somewhat unpredictably among people, depending on their stake in the outcome. This will make subjective predictions more uncertain and less transparent than those based on models. (C) 2004 Elsevier SAS. All rights reserved.

Integer matrix diagonalization

We consider algorithms for computing the Smith normal form of integer matrices. A variety of different strategies have been proposed, primarily aimed at avoiding the major obstacle that occurs in such computations-explosive growth in size of intermediate entries. We present a new algorithm with excellent performance. We investigate the complexity of such computations, indicating relationships with NP-complete problems. We also describe new heuristics which perform well in practice. Wie present experimental evidence which shows our algorithm outperforming previous methods. (C) 1997 Academic Press Limited.

Cognitive impairment and dementia in neurocysticercosis A cross-sectional controlled study

Objectives: Neurocysticercosis (NCYST) is the most frequent CNS parasitic disease worldwide, affecting more than 50 million people. However, some of its clinical findings, such as cognitive impairment and dementia, remain poorly characterized, with no controlled studies conducted so far. We investigated the frequency and the clinical profile of cognitive impairment and dementia in a sample of patients with NCYST in comparison with cognitively healthy controls (HC) and patients with cryptogenic epilepsy (CE). Methods: Forty treatment-naive patients with NCYST, aged 39.25 +/- 10.50 years and fulfilling absolute criteria for definitive active NCYST on MRI, were submitted to a comprehensive cognitive and functional evaluation and were compared with 49 HC and 28 patients with CE of similar age, educational level, and seizure frequency. Results: Patients with NCYST displayed significant impairment in executive functions, verbal and nonverbal memory, constructive praxis, and verbal fluency when compared with HC (p < 0.05). Dementia was diagnosed in 12.5% patients with NCYST according to DSM-IV criteria. When compared with patients with CE, patients with NCYST presented altered working and episodic verbal memory, executive functions, naming, verbal fluency, constructive praxis, and visual-spatial orientation. No correlation emerged between cognitive scores and number, localization, or type of NCYST lesions on MRI. Conclusions: Cognitive impairment was ubiquitous in this sample of patients with active neurocysticercosis (NCYST). Antiepileptic drug use and seizure frequency could not account for these features. Dementia was present in a significant proportion of patients. These data broaden our knowledge on the clinical presentations of NCYST and its impact in world public health. Neurology (R) 2010;74:1288-1295

Constructing a class of designs with proportional balance

Text serves as a sequel to 'Computational and Constructive Design Theory,' c1996; containing research papers and surveys of recent research work on design construction and computer-aided study of designs. For researchers in theory of computational designs.

Enhancing emancipatory systems methodologies for sustainable development

Our interest lies in applying the principles of critical systems thinking to human activity systems in developing countries in situations where issues of natural resource sustainability constrain the feasible set of long-term strategies. The concept of sustainable development provides an expanded domain for critical systems thinking. The fundamental values underpinning sustainable development are that both intragenerational and intergenerational equity are important. As a consequence, key stakeholders are often excluded from power-sharing within current social systems. Addressing these issues requires renewed focus on emancipatory commitment and methodologies. To date, Ulrich's critical systems heuristics is the only critical systems methodology that offers practicable tools for emancipation. A case study analysis in Tigray, northern Ethiopia, provides insights in relation to the application of critical system heuristics to issues of sustainable development and highlights the need to extend the use of critical systems heuristics beyond the design and monitoring of structured interventions.

Some factors affecting diagnostic accuracy

Diagnosis involves a complex and overlapping series of steps, each of which may be a source of error and of variability between clinicians. This variation may involve the ability to elicit relevant information from the client or animal, in the accuracy, objectivity and completeness of relevant memory stores, and in psychological attributes including tolerance for uncertainty and willingness to engage in constructive self-criticism. The diagnostic acumen of an individual clinician may not be constant, varying with external and personal factors, with different clients and cases, and with the use made of tests. In relation to clients, variations may occur in the ability to gain their confidence, to ask appropriate questions and to evaluate accurately both verbal and nonverbal responses. Tests may introduce problems of accuracy, validity, sensitivity, specificity, interpretation and general appropriateness for the case. Continuing effectiveness as a diagnostician therefore requires constant attention to the maintenance of adequate and up-to-date skills and knowledge relating to the animals and their diseases and to tests, and of sensitive interpersonal skills.

Mathematical methods for spatially cohesive reserve design

The problem of designing spatially cohesive nature reserve systems that meet biodiversity objectives is formulated as a nonlinear integer programming problem. The multiobjective function minimises a combination of boundary length, area and failed representation of the biological attributes we are trying to conserve. The task is to reserve a subset of sites that best meet this objective. We use data on the distribution of habitats in the Northern Territory, Australia, to show how simulated annealing and a greedy heuristic algorithm can be used to generate good solutions to such large reserve design problems, and to compare the effectiveness of these methods.