An algorithm for semi-infinite polynomial optimization

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A linear optimization technique for graph pebbling

Graph pebbling is a network model for studying whether or not a given supply of discrete pebbles can satisfy a given demand via pebbling moves. A pebbling move across an edge of a graph takes two pebbles from one endpoint and places one pebble at the other endpoint; the other pebble is lost in transit as a toll. It has been shown that deciding whether a supply can meet a demand on a graph is NP-complete. The pebbling number of a graph is the smallest t such that every supply of t pebbles can satisfy every demand of one pebble. Deciding if the pebbling number is at most k is NP 2 -complete. In this paper we develop a tool, called theWeight Function Lemma, for computing upper bounds and sometimes exact values for pebbling numbers with the assistance of linear optimization. With this tool we are able to calculate the pebbling numbers of much larger graphs than in previous algorithms, and much more quickly as well. We also obtain results for many families of graphs, in many cases by hand, with much simpler and remarkably shorter proofs than given in previously existing arguments (certificates typically of size at most the number of vertices times the maximum degree), especially for highly symmetric graphs. Here we apply theWeight Function Lemma to several specific graphs, including the Petersen, Lemke, 4th weak Bruhat, Lemke squared, and two random graphs, as well as to a number of infinite families of graphs, such as trees, cycles, graph powers of cycles, cubes, and some generalized Petersen and Coxeter graphs. This partly answers a question of Pachter, et al., by computing the pebbling exponent of cycles to within an asymptotically small range. It is conceivable that this method yields an approximation algorithm for graph pebbling.

A parameter-free approach for solving combinatorial optimization problems through biased randomization of efficient heuristics

This paper discusses the use of probabilistic or randomized algorithms for solving combinatorial optimization problems. Our approach employs non-uniform probability distributions to add a biased random behavior to classical heuristics so a large set of alternative good solutions can be quickly obtained in a natural way and without complex conguration processes. This procedure is especially useful in problems where properties such as non-smoothness or non-convexity lead to a highly irregular solution space, for which the traditional optimization methods, both of exact and approximate nature, may fail to reach their full potential. The results obtained are promising enough to suggest that randomizing classical heuristics is a powerful method that can be successfully applied in a variety of cases.

On the stability of the optimal value and the optimal set in optimization problems

The paper develops a stability theory for the optimal value and the optimal set mapping of optimization problems posed in a Banach space. The problems considered in this paper have an arbitrary number of inequality constraints involving lower semicontinuous (not necessarily convex) functions and one closed abstract constraint set. The considered perturbations lead to problems of the same type as the nominal one (with the same space of variables and the same number of constraints), where the abstract constraint set can also be perturbed. The spaces of functions involved in the problems (objective and constraints) are equipped with the metric of the uniform convergence on the bounded sets, meanwhile in the space of closed sets we consider, coherently, the Attouch-Wets topology. The paper examines, in a unified way, the lower and upper semicontinuity of the optimal value function, and the closedness, lower and upper semicontinuity (in the sense of Berge) of the optimal set mapping. This paper can be seen as a second part of the stability theory presented in [17], where we studied the stability of the feasible set mapping (completed here with the analysis of the Lipschitz-like property).

Artificial Snow Optimization in Winter Sport Destinations Using a Multi-agent Simulation

This paper presents the Juste-Neige system for predicting the snow height on the ski runs of a resort using a multi-agent simulation software. Its aim is to facilitate snow cover management in order to i) reduce the production cost of artificial snow and to improve the profit margin for the companies managing the ski resorts; and ii) to reduce the water and energy consumption, and thus to reduce the environmental impact, by producing only the snow needed for a good skiing experience. The software provides maps with the predicted snow heights for up to 13 days. On these maps, the areas most exposed to snow erosion are highlighted. The software proceeds in three steps: i) interpolation of snow height measurements with a neural network; ii) local meteorological forecasts for every ski resort; iii) simulation of the impact caused by skiers using a multi-agent system. The software has been evaluated in the Swiss ski resort of Verbier and provides useful predictions.

A conceptual framework to assess the effectiveness of HIV prevention

Aim: The relative effectiveness of different methods of prevention of HIV transmission is a subject of debate that is renewed with the integration of each new method. The relative weight of values and evidence in decision-making is not always clearly defined. Debate is often confused, as the proponents of different approaches address the issue at different levels of implementation. This paper defines and delineates the successive levels of analysis of effectiveness, and proposes a conceptual framework to clarify debate. Method / Issue: Initially inspired from work on contraceptive effectiveness, a first version of the conceptual framework was published in 1993 with definition of the Condom Effectiveness Matrix (Spencer, 1993). The framework has since integrated and further developed thinking around distinctions made between efficacy and effectiveness and has been applied to HIV prevention in general. Three levels are defined: theoretical effectiveness (ThE), use-effectiveness (UseE) and population use-effectiveness (PopUseE). For example, abstinence and faithfulness, as proposed in the ABC strategy, have relatively high theoretical effectiveness but relatively low effectiveness at subsequent levels of implementation. The reverse is true of circumcision. Each level is associated with specific forms of scientific enquiry and associated research questions: basic and clinical sciences with ThE; clinical and social sciences with UseE; epidemiology and social, economic and political sciences with PopUseE. Similarly, the focus of investigation moves from biological organisms, to the individual at the physiological and then psychological, social and ecological level, and finally takes as perspective populations and societies as a whole. The framework may be applied to analyse issues on any approach. Hence, regarding consideration of HIV treatment as a means of prevention, examples of issues at each level would be: ThE: achieving adequate viral suppression and non-transmission to partners; UseE: facility and degree of adherence to treatment and medical follow-up; PopUseE: perceived validity of strategy, feasibility of achieving adequate population coverage. Discussion: Use of the framework clarifies the questions that need to be addressed at all levels in order to improve effectiveness. Furthermore, the interconnectedness and complementary nature of research from the different scientific disciplines and the relative contribution of each become apparent. The proposed framework could bring greater rationality to the prevention effectiveness debate and facilitate communication between stakeholders.

Semi-supervised segmentation of ultrasound images based on patch representation and continuous min cut.

Ultrasound segmentation is a challenging problem due to the inherent speckle and some artifacts like shadows, attenuation and signal dropout. Existing methods need to include strong priors like shape priors or analytical intensity models to succeed in the segmentation. However, such priors tend to limit these methods to a specific target or imaging settings, and they are not always applicable to pathological cases. This work introduces a semi-supervised segmentation framework for ultrasound imaging that alleviates the limitation of fully automatic segmentation, that is, it is applicable to any kind of target and imaging settings. Our methodology uses a graph of image patches to represent the ultrasound image and user-assisted initialization with labels, which acts as soft priors. The segmentation problem is formulated as a continuous minimum cut problem and solved with an efficient optimization algorithm. We validate our segmentation framework on clinical ultrasound imaging (prostate, fetus, and tumors of the liver and eye). We obtain high similarity agreement with the ground truth provided by medical expert delineations in all applications (94% DICE values in average) and the proposed algorithm performs favorably with the literature.

Catalonia’s participation in calls of the EU 7th Framework Programme for RTD. Period 2007-2009

English translation of the Executive summary of the report “Catalonia’s participation in calls of the EU 7th Framework Programme for RTD. Period 2007-2009” drawn up by researchers of the AQR Research Group – Research Institute of Applied Economics (IREA) of the University of Barcelona. It aims to find out the reality of the Catalonia’s participation in the EU 7th Framework Programme, the main European financial instrument for research during the period 2007-2009.

Department for Social Development, Belfast City Centre Northside Urban Village, Draft Regeneration Framework. Health Impact Assessment Report

IPH conducted a rapid HIA appraisal in response to the consultation on DSD Draft Regeneration Framework. The Department for Social Development (DSD) has developed a Draft Regeneration Framework for the North West Quarter Part 2 area of Belfast City Centre, to be known as the Northside Urban Village. The Framework, which outlines the vision for the redevelopment of an inner city area of Belfast was released for public consultation in April 2008. In responding to this consultation, the Institute of Public Health in Ireland (IPH) conducted a Health Impact Assessment (HIA) in order to assess how the proposed Framework might impact on the health of those living in or close to the area as well as the wider Belfast population. The key recommendations which resulted from this process have been presented to the Department. This paper presents an overview of the HIA conducted.

IPH response to DSD Urban Regeneration and Community Development Policy Framework Consultation

The Urban Regeneration and Community Development Policy Framework for Northern Ireland sets out for DSD and its partners, clear priorities for urban regeneration and community development programmes, both before and after the operational responsibility for these is transferred to councils under the reform of local government. Four policy objectives have been developed, which will focus on the underlying structural problems in urban areas and also help strengthen community development throughout Northern Ireland. The policy objectives are as follows: Policy Objective 1 – To tackle area-based deprivation: Policy Objective 2 – To strengthen the competitiveness of our towns and cities: Policy Objective 3 – To improve linkages between areas of need and areas of opportunity: and Policy Objective 4 –To develop more cohesive and engaged communities. Key points from IPH response Urban regeneration and community development provide a basis for addressing the social determinants of health and reducing inequalities in health. This policy framework presents an opportunity for coherence and complementarity with ‘Fit and Well - Changing Lives’ as part of government’s overall approach to tackling health inequalities. It is now well established that a focus on early years’ interventions and family support services yields significant returns, so prioritising action in these areas is essential. Defined action plans on child poverty are essential if this policy framework is to make a real and lasting difference in deprived urban areas. Development of the environmental infrastructure to improve health in deprived areas should be supported by well-planned monitoring and evaluation. Linking the policy framework to economic development and local community plans will enhance effectiveness in the areas of education, job creation, commercial investment and access to services, which in turn are critical for the economic growth and stability of urban communities. Community profile data and health intelligence (as available through IPH Health Well) could usefully inform central and local government in terms of resource allocation and targeted service delivery.

IPH response to Your Health is Your Wealth – Health and Wellbeing Framework 2012- 2020 (Department of Health)

The remit of the Institute of Public Health in Ireland (IPH) is to promote cooperation for public health between Northern Ireland and the Republic of Ireland in the areas of research and information, capacity building and policy advice. Our approach is to support Departments of Health and their agencies in both jurisdictions, and maximise the benefits of all-island cooperation to achieve practical benefits for people in Northern Ireland and the Republic of Ireland. The Department of Health is developing a Health and Wellbeing policy to improve the health of the population and reduce health inequalities by addressing causes of preventable illnesses. The Policy Framework is at an advanced stage with a number of background analytical documents prepared and published on the Department website to allow views to be incorporated into final drafts.  IPH responded to the consultation call in 2011 and we welcome the placement of these supporting documents on the Department website with the request for additional comments.

IPH Response to draft Framework for Sustainable Development for Ireland

The Minister for the Environment, Community and Local Government, Mr Phil Hogan has launched a draft Framework for Sustainable Development for Ireland for public consultation. The objectives of the draft Framework are to identify and prioritise policy areas and mechanisms where a sustainable development approach will add value and enable continuous improvement of quality of life for current and future generations and set out clear measures, responsibilities and timelines in an implementation plan.

IPH response to NICE consultation on new indicators for Quality and Outcomes Framework (QOF)

IPH responded to the consultation on potential new indicators for the 2013/14 Quality and Outcomes Framework (QOF) in the UK. The 20 potential new indicators relate to chronic obstructive pulmonary disease (COPD), heart failure, coronary heart disease, diabetes, depression, hypertension, rheumatoid arthritis, asthma and cancer. The consultation asked people to consider whether there were any barriers to the implementation of the care described by any of the indicators; whether there were potential unintended consequences to the implementation of any of the indicators; whether there was potential for differential impact (in respect of age, disability, gender reassignment, pregnancy and maternity, race, religion or belief, sex and sexual orientation); and whether the indicators may have an adverse impact in different groups in the community.”

IPH response to 'Your Health is Your Wealth' - Public Health Policy Framework 2012-2020

The Department of Health (Republic of Ireland) is developing a public health policy, which aims to improve the health of the population and reduce health inequalities by addressing the causes of preventable illnesses.  The aim is to develop a policy for a healthier population for all ages and all sectors in society.  To succeed in developing and implementing a first-class public health policy, in which everyone is encouraged to play a part in protecting and improving the nation’s health, a consultation process was put in place  to ensure wide engagement.