Lin-Kernighan Heuristic Adaptations for the Generalized Traveling Salesman Problem

The Lin-Kernighan heuristic is known to be one of the most successful heuristics for the Traveling Salesman Problem (TSP). It has also proven its efficiency in application to some other problems. In this paper we discuss possible adaptations of TSP heuristics for the Generalized Traveling Salesman Problem (GTSP) and focus on the case of the Lin-Kernighan algorithm. At first, we provide an easy-to-understand description of the original Lin-Kernighan heuristic. Then we propose several adaptations, both trivial and complicated. Finally, we conduct a fair competition between all the variations of the Lin-Kernighan adaptation and some other GTSP heuristics. It appears that our adaptation of the Lin-Kernighan algorithm for the GTSP reproduces the success of the original heuristic. Different variations of our adaptation outperform all other heuristics in a wide range of trade-offs between solution quality and running time, making Lin-Kernighan the state-of-the-art GTSP local search.Comment: 25 page

Drag-free estimation feasibility study

A drag compensation system for solar probes and other spacecraft that require a drag-free capability is presented. Estimation techniques, derived from modern control theory, are proposed

Simulating the Gradually Deteriorating Performance of an RTG

Degra (now in version 3) is a computer program that simulates the performance of a radioisotope thermoelectric generator (RTG) over its lifetime. Degra is provided with a graphical user interface that is used to edit input parameters that describe the initial state of the RTG and the time-varying loads and environment to which it will be exposed. Performance is computed by modeling the flows of heat from the radioactive source and through the thermocouples, also allowing for losses, to determine the temperature drop across the thermocouples. This temperature drop is used to determine the open-circuit voltage, electrical resistance, and thermal conductance of the thermocouples. Output power can then be computed by relating the open-circuit voltage and the electrical resistance of the thermocouples to a specified time-varying load voltage. Degra accounts for the gradual deterioration of performance attributable primarily to decay of the radioactive source and secondarily to gradual deterioration of the thermoelectric material. To provide guidance to an RTG designer, given a minimum of input, Degra computes the dimensions, masses, and thermal conductances of important internal structures as well as the overall external dimensions and total mass

Effects of point-count duration on estimated detection probabilities and occupancy of breeding birds

Increasingly, point-count data are used to estimate occupancy, the probability that a species is present at a given location; occupancy accounts for imperfect detection, the probability that a species is detected given that it is present. To our knowledge, effects of sampling duration on inferences from models of bird occupancy have not been evaluated. Our objective was to determine whether changing count duration from 5 to 8min affected inferences about the occupancy of birds sampled in the Chesapeake Bay Lowlands (eastern United States) and the central and western Great Basin (western United States) in 2012 and 2013. We examined the proportion of species (two doves, one cuckoo, two swifts, five hummingbirds, 11 woodpeckers, and 122 passerines) for which estimates of detection probability were 0.3. For species with single-season detection probabilities 0.3, we compared occupancy estimates derived from 5- and 8-min counts. We also compared estimates for three species sampled annually for 5yr in the central Great Basin. Detection probabilities based on both the 5- and 8-min counts were 0.3 for 40% 3% of the species in an ecosystem. Extending the count duration from 5 to 8min increased the detection probability to 0.3 for 5% +/- 0.5% of the species. We found no difference in occupancy estimates that were based on 5- versus 8-min counts for species sampled over two or five consecutive years. However, for 97% of species sampled over 2yr, precision of occupancy estimates that were based on 8-min counts averaged 12% +/- 2% higher than those based on 5-min counts. We suggest that it may be worthwhile to conduct a pilot season to determine the number of locations and surveys needed to achieve detection probabilities that are sufficiently high to estimate occupancy for species of interest

Skin microvascular vasodilatory capacity in offspring of two parents with Type 2 diabetes

Aims<br/> Microvascular dysfunction occurs in Type 2 diabetes and in subjects with fasting hyperglycaemia. It is unclear whether this dysfunction relates to dysglycaemia. This study investigated in normogylcaemic individuals whether a genetic predisposition to diabetes, or indices of insulin resistance including endothelial markers, were associated with impaired microvascular function.<br/> Methods<br/> Maximum microvascular hyperaemia to local heating of the skin was measured using laser Doppler flowmetry in 21 normoglycaemic subjects with no family history of diabetes (Group 1) and 21 normoglycaemic age, sex and body mass index-matched offspring of two parents with Type 2 diabetes (Group 2). <br/>Results<br/> Although Group 2 had normal fasting plasma glucose and glucose tolerance tests, the 120-min glucose values were significantly higher at 6.4 (5.3-6.6) mmol/l (median (25th-75th centile)) than the control group at 4.9 (4.6-5.9) mmol/l (P=0.005) and the insulinogenic index was lower at 97.1 (60.9-130.8) vs. 124.0 (97.2-177.7) (P=0.027). Skin maximum microvascular hyperaemia (Group 1: 1.56 (1.39- 1.80) vs. Group 2: 1.53 (1.30-1.98) V, P=0.99) and minimum microvascular resistance which normalizes the hyperaemia data for blood pressure (Group 1: 52.0 (43.2-67.4) vs. Group 2: 56.0 (43.7-69.6) mmHgN, P=0.70) did not differ in the two groups. Significant positive associations occurred between minimum microvascular resistance and indices of the insulin resistance syndrome; plasminogen activator inhibitor type 1 (R-s=0.46, P=0.003), t-PA (R-s=0.36, P=0.03), total cholesterol (R-s=0.35, P=0.02), and triglyceride concentration (R-s=0.35, P=0.02), and an inverse association with insulin sensitivity (R-s=-0.33, P=0.03).<br/> Conclusions<br/> In normoglycaemic adults cutaneous microvascular vasodilatory capacity is associated with features of insulin resistance syndrome, particularly with plasminogen activator inhibitor type 1. A strong family history of Type 2 diabetes alone does not result in impairment in the maximum hyperaemic response

Achieving equity through 'gender autonomy': the challenges for VET policy and practice

This paper is based on research carried out in an EU Fifth Framework project on 'Gender and Qualification'. The research partners from five European countries investigated the impact of gender segregation in European labour markets on vocational education and training, with particular regard to competences and qualifications. The research explored the part played by gender in the vocational education and training experiences of (i) young adults entering specific occupations in child care, electrical engineering and food preparation/service (ii) adults changing occupations

Intersectionality, identity work and migrant progression from low-paid work: A critical realist approach

This article contributes to developing intersectionality theory by deepening understanding of how patriarchy and racism interact with other structural factors to influence low-paid migrants’ progression attempts. Using a critical realist approach and analysing interviews of 31 female and male migrants employed in five large organizations in Scotland and England, we reveal how major structural factors influence their main forms of identity work and the resources that they draw on in both the workplace and home. The feminist approach undertaken by this study makes significant advances to organizational intersectional theory in three ways. Firstly, it highlights the importance of examining the interaction of the influence of patriarchy within the home with racism and other structuring forces within the workplace. Secondly, it reveals how combinations of constraints and enablements that intersect with gendered and racialized identity work create formidable barriers to progression. Thirdly, it explores migrants’ differential access to diverse resources, including financial, social, discursive and psychological resources in both spheres over time. These findings reinforce the need for policy actions that recognize the interaction of structural factors which influence female and male migrant progression and the need for support within and beyond the workplace

Preparing to work: dramaturgy, cynicism and normative ‘remote’ control in the socialization of graduate recruits in management consulting

online) This paper examines the socialization of graduate recruits into a knowledge intensive labour process and organizational culture. Theoretically the paper draws upon the idea of ‘preparing for work’ to position this early socialization as a crucial moment in the production of subjectivities suited (and booted) for the labour process of management consulting. Empirically the paper reports on a two-day induction session for new graduate recruits joining a global management consultancy and their responses to this training. Particular attention is given to the use of role-play and a dramaturgical workshop used in part of the training process. The paper argues that the utilization of dramaturgy in training is consistent with the overall approach to control developed in the firm in response to the fact that the labour process of consulting is often conducted on client sites, away from any direct supervisory gaze. As such, the consultants were subjected to a form of cultural control that was designed to function independently of direct supervision. This control did not operate directly upon the new employees professed values, however, but at one step removed so that a ‘cynical distance’ from the content of the organization’s culture was accepted so long as a professional ‘ethic of behaviour’ was established. By focusing on an ‘ethic of behaviour’ these young professionals were encouraged to internalize a self-control akin to that of an actor, rather than internalizing the corporate values entirely

Development of the NASA/Baylor VAD

A cooperative effort between the NASA/Johnson Space Center (JSC) and the Baylor College of Medicine (BCM) has been underway since 1988 to develop a long-term implantable Ventricular Assist Device (VAD). The VAD is intended to boost the cardiac output of patients with deteriorated cardiac function. For many of these patients, the best alternative is heart transplantation. Heart transplantation is a complex and expensive procedure and usually requires a long waiting period for a donor heart. The condition of the patient often deteriorates during this waiting period which complicates the pre and post-operative care. Because of these factors, the need for a long-term implantable VAD for use as a bridge-to-transplant device or as a permanent assist device has become the focus of much research. The need for a VAD has been estimated at 50,000 to 60,000 patients per year in the United States alone. A device which satisfies all the system performance and reliability requirements has yet to be achieved. However, the development of the NASA/Baylor VAD has progressed to a state in which commercial viability can being to be considered. The device is small, simple, efficient and reliable which meets all requirements for a totally implantable VAD