An extended abstract: A heuristic repair method for constraint-satisfaction and scheduling problems

The work described in this paper was inspired by a surprisingly effective neural network developed for scheduling astronomical observations on the Hubble Space Telescope. Our heuristic constraint satisfaction problem (CSP) method was distilled from an analysis of the network. In the process of carrying out the analysis, we discovered that the effectiveness of the network has little to do with its connectionist implementation. Furthermore, the ideas employed in the network can be implemented very efficiently within a symbolic CSP framework. The symbolic implementation is extremely simple. It also has the advantage that several different search strategies can be employed, although we have found that hill-climbing methods are particularly well-suited for the applications that we have investigated. We begin the paper with a brief review of the neural network. Following this, we describe our symbolic method for heuristic repair

The min-conflicts heuristic: Experimental and theoretical results

This paper describes a simple heuristic method for solving large-scale constraint satisfaction and scheduling problems. Given an initial assignment for the variables in a problem, the method operates by searching through the space of possible repairs. The search is guided by an ordering heuristic, the min-conflicts heuristic, that attempts to minimize the number of constraint violations after each step. We demonstrate empirically that the method performs orders of magnitude better than traditional backtracking techniques on certain standard problems. For example, the one million queens problem can be solved rapidly using our approach. We also describe practical scheduling applications where the method has been successfully applied. A theoretical analysis is presented to explain why the method works so well on certain types of problems and to predict when it is likely to be most effective

Contagion and learning in business networks

The purpose of this study is to examine network learning through the application of contagion theories. The transmission of knowledge, sharing of resources, and facilitation of learning through contagion has interested both business-to-business and economic geography researchers. This study responds to calls in both research traditions for research into knowledge and learning at the level of an interfirm network. More specifically, it focuses on developing an understanding of how the contagion of knowledge and ideas and the co-ordination of activities within a network tales place. We achieve this by drawing upon research in both network relationships dynamics and learning processes to investigate the causal mechanisms that drive contagion. We focus on two types of contagion: contagion by cohesion (i.e. the presences and closeness of direct contact with others in the network), and contagion by structural equivalence (i.e. where influence is related to the structural patterns of relationships in the network). We also identify two key mechanisms that act as a barrier to such contagion: isolation and immunity. We explore the implications of these findings for network learning opportunities, specifically learning-by-doing, learning-by-using, and learning-by-interacting

Scoping study on natural resources and climate change in Southeast Asia with a focus on agriculture. Final report

Climate change / Natural resources / Environmental effects / Agroecology / Agricultural production / Crops / Cropping systems / Farming systems / Livestock / Fisheries / Food security / Water management / Economic aspects / Rural poverty / Policy / Nutrient management / South East Asia / Cambodia / Laos / Thailand / Vietnam / Myanmar / China / Greater Mekong Subregion / Tonle Sap / Yunnan

Involving customers in innovation: knowledgeability and agency as process variables

Purpose: Recent research places an increased emphasis on the inclusion of the customer in value creation, learning, and innovation processes yet there remains a gap in our understanding of just how such customer involvement may work. This paper seeks to address this gap by examining two aspects of customer involvement; their knowledgeability and their agency. In addition, we explore three boundaries (semantic, syntactic, and pragmatic) across which relationship development occurs and which mayfacilitate and/or inhibit value co-creation, collaborative learning, and innovation processes. Design/methodology/approach: We utilised three case studies. Two were large scale construction projects in the UK, and one was a global professional accounting firm in the USA. Findings: Customers may become frustrated if not allowed to exercise their agency. However, their involvement can create tensions for suppliers who may have to become more tolerant of divergent goals. In respect of knowledgeability, we found that constraint satisfaction is important in allowing customers to reconcile their personal knowledge schema with that of the collective schema. However, we also noted that customer knowledgeability brings with it challenges for suppliers, who must find ways to add value for such customers. Research implications: We pose a number of further questions relating to the agency and knowledgeability of customers and their inclusion in value co-creation, collaborative learning, and innovation processes. We also highlight the need for guidance in identifying and minimising the barriers to crossing semantic, syntactic and pragmatic boundaries between customers and suppliers. Originality/value: We make an important contribution to research in the field in that we investigate how the inclusion of the customer in business networksalters current assumptions and practices

Climate change, water and agriculture in the Greater Mekong subregion

Climate change / Adaptation / Indicators / Water resource management / River basins / Water availability / Water quality / Groundwater / Fisheries / Ecosystems / Water power / Population growth / Land use / Biofuels / Sea level / South East Asia / Cambodia / Laos / Myanmar / Thailand / Vietnam / China / Greater Mekong Subregion / Yunnan Province

Probing the structure of the cold dark matter halo with ancient mica

Mica can store (for >1 Gy) etchable tracks caused by atoms recoiling from WIMPs. Ancient mica is a directional detector despite the complex motions it makes with respect to the WIMP "wind". We can exploit the properties of directionality and long integration time to probe for structure in the dark matter halo of our galaxy. We compute a sample of possible signals in mica for a plausible model of halo structure.Comment: 7 pages, 2 figure

Viral suppression following switch to second-line antiretroviral therapy: associations with nucleoside reverse transcriptase inhibitor resistance and subtherapeutic drug concentrations prior to switch.

BACKGROUND: High rates of second-line antiretroviral treatment (ART) failure are reported. The association with resistance and nonadherence on switching to second-line ART requires clarification. METHODS: Using prospectively collected data from patients in South Africa, we constructed a cohort of patients switched to second-line ART (1 January 2003 through 31 December 2008). Genotyping and drug concentrations (lamivudine, nevirapine, and efavirenz) were measured on stored samples preswitch. Their association with viral load (VL) <400 copies/mL by 15 months was assessed using modified Poisson regression. RESULTS: One hundred twenty-two of 417 patients (49% male; median age, 36 years) had genotyping (n = 115) and/or drug concentrations (n = 80) measured. Median CD4 count and VL at switch were 177 cells/µL (interquartile range [IQR], 77-263) and 4.3 log10 copies/mL (IQR, 3.8-4.7), respectively. Fifty-five percent (n = 44/80) had subtherapeutic drug concentrations preswitch. More patients with therapeutic vs subtherapeutic ART had resistance (n = 73): no major mutations (3% vs 51%), nonnucleoside reverse transcriptase inhibitor (94% vs 44%), M184V/I (94% vs 26%), and ≥ 1 thymidine analogue mutations (47% vs 18%), all P = .01; and nucleoside reverse transcriptase inhibitor (NRTI) cross-resistance mutations (26% vs 13%, P = .23). Following switch, 68% (n = 83/122) achieved VL <400 copies/mL. Absence of NRTI mutations and subtherapeutic ART preswitch were associated with failure to achieve VL <400 copies/mL. CONCLUSIONS: Nonadherence, suggested by subtherapeutic ART with/without major resistance mutations, significantly contributed to failure when switching regimen. Unresolved nonadherence, not NRTI resistance, drives early second-line failure