Relative Convex Hull Determination from Convex Hulls in the Plane

A new algorithm for the determination of the relative convex hull in the plane of a simple polygon A with respect to another simple polygon B which contains A, is proposed. The relative convex hull is also known as geodesic convex hull, and the problem of its determination in the plane is equivalent to find the shortest curve among all Jordan curves lying in the difference set of B and A and encircling A. Algorithms solving this problem known from Computational Geometry are based on the triangulation or similar decomposition of that difference set. The algorithm presented here does not use such decomposition, but it supposes that A and B are given as ordered sequences of vertices. The algorithm is based on convex hull calculations of A and B and of smaller polygons and polylines, it produces the output list of vertices of the relative convex hull from the sequence of vertices of the convex hull of A.Comment: 15 pages, 4 figures, Conference paper published. We corrected two typing errors in Definition 2: $I_S$ has to be defined based on $O_S$, and $I_E$ has to be defined based on $O_E$ (not just using $O$). These errors appeared in the text of the original conference paper, which also contained the pseudocode of an algorithm where $I_S$ and $I_E$ appeared as correctly define

A Sound and Complete Abstraction for Reasoning about Parallel Prefix Sums

Prefix sums are key building blocks in the implementation of many concurrent software applications, and recently much work has gone into efficiently implementing prefix sums to run on massively par-allel graphics processing units (GPUs). Because they lie at the heart of many GPU-accelerated applications, the correctness of prefix sum implementations is of prime importance. We introduce a novel abstraction, the interval of summations, that allows scalable reasoning about implementations of prefix sums. We present this abstraction as a monoid, and prove a sound-ness and completeness result showing that a generic sequential pre-fix sum implementation is correct for an array of length n if and only if it computes the correct result for a specific test case when instantiated with the interval of summations monoid. This allows correctness to be established by running a single test where the in

Multiobjective Local Search Techniques for Evolutionary Polygonal Approximation

Proceedings of: 10th International Symposium on Distributed Computing and Artificial Intelligence . University of Salamanca (DCAI 2013). Salamanca, Spain, Spain, May 22-24, 2013.Polygonal approximation is based on the division of a closed curve into a set of segments. This problem has been traditionally approached as a single-objective optimization issue where the representation error was minimized according to a set of restrictions and parameters. When these approaches try to be subsumed into more recent multi-objective ones, a number of issues arise. Current work successfully adapts two of these traditional approaches and introduces them as initialization procedures for a MOEA approach to polygonal approximation, being the results, both for initial and final fronts, analyzed according to their statistical significance over a set of traditional curves from the domain.This work was supported in part by Projects MEyC TEC2012-37832-C02-01, MEyC TEC2011-28626-C02-02 and CAM CONTEXTS (S2009/TIC-1485).Publicad

The re-professionalization of the police in England and Wales

In this article contemporary police claims to professional status are analysed and related to a new structure of police regulation in England and Wales. It is argued that the notion of the police as a profession is not new and, unlike police and academic commentary, analysis of this subject, should draw on sociological understandings of professions. The wider policy context within which claims to professionalisation are made is also considered. It is argued that a new, loosely-coupled system of regulation has been developed in England and Wales. Policing’s professional body, the College of Policing, is central to this regulatory framework that has placed government at a distance from constabularies and police representative associations. Finally, some of the consequences of the hybrid system are considered and benefits of the framework of analysis proposed are discussed

How old are you? Newborn gestational age discriminates neonatal resuscitation practices in the Italian debate

<p>Abstract</p> <p>Background</p> <p>Multidisciplinary study groups have produced documents in an attempt to support decisions regarding whether to resuscitate "at risk" newborns or not. Moreover, there has been an increasingly insistent request for juridical regulation of neonatal resuscitation practices as well as for clarification of the role of parents in decisions regarding this kind of assistance. The crux of the matter is whether strict guidelines, reference standards based on the parameter of gestational age and authority rules are necessary.</p> <p>Discussion</p> <p>The Italian scenario reflects the current animated debate, illustrating the difficulty intrinsic in rigid guidelines on the subject, especially when gestational age is taken as a reference parameter for the medical decision.</p> <p>Summary</p> <p>Concerning the decision to interrupt or not to initiate resuscitation procedures on low gestational age newborns, physicians do not need rigid rules based on inflexible gestational age and birth weight guidelines. Guidance in addressing the difficult and trying issues associated with infants born at the margins of viability with a realistic assessment of the infant's clinical condition must be based on the infant's best interests, with clinicians and parents entering into what has been described as a "partnership of care".</p

From offender to victim-oriented monitoring : a comparative analysis of the emergence of electronic monitoring systems in Argentina and England and Wales

The increasingly psychological terrain of crime and disorder management has had a transformative impact upon the use of electronic monitoring technologies. Surveillance technologies such as electronic monitoring ‑ EM, biometrics, and video surveillance have flourished in commercial environments that market the benefits of asocial technologies in managing disorderly behavior and which, despite often chimerical crime prevention promises, appeal to the ontologically insecure social imagination. The growth of EM in criminal justice has subsequently taken place despite, at best, equivocal evidence that it protects the public and reduces recidivism. Innovative developments in Portugal, Argentina and the United States have re-imagined EM technologies as more personalized devices that can support victims rather than control offenders. These developments represent a re-conceptualization of the use of the technology beyond the neoliberal prism of rational choice theories and offender-oriented thinking that influenced first generation thinking about EM. This paper identifies the socio-political influences that helped conceptualize first generation thinking about EM as, firstly, a community sentence and latterly, as a technique of urban security. The paper reviews attempts to theorize the role and function of EM surveillance technologies within and beyond criminal justice and explores the contribution of victimological perspectives to the use of EM 2.0

Cardiac Tissue Engineering: Implications for Pediatric Heart Surgery

Children with severe congenital malformations, such as single-ventricle anomalies, have a daunting prognosis. Heart transplantation would be a therapeutic option but is restricted due to a lack of suitable donor organs and, even in case of successful heart transplantation, lifelong immune suppression would frequently be associated with a number of serious side effects. As an alternative to heart transplantation and classical cardiac reconstructive surgery, tissue-engineered myocardium might become available to augment hypomorphic hearts and/or provide new muscle material for complex myocardial reconstruction. These potential applications of tissue engineered myocardium will, however, impose major challenges to cardiac tissue engineers as well as heart surgeons. This review will provide an overview of available cardiac tissue-engineering technologies, discuss limitations, and speculate on a potential application of tissue-engineered heart muscle in pediatric heart surgery

The moral economy of security

In this article we draw upon our recent research into security consumption to answer two questions: first, under what conditions do people experience the buying and selling of security goods and services as morally troubling? Second, what are the theoretical implications of understanding private security as, in certain respects, tainted trade? We begin by drawing on two bodies of work on morality and markets (one found in political theory, the other in cultural sociology) in order to develop what we call a moral economy of security. We then use this theoretical resource to conduct an anatomy of the modes of ambivalence and unease that the trade in security generates. Three categories organize the analysis: blocked exchange; corrosive exchange; and intangible exchange. In conclusion, we briefly spell out the wider significance of our claim that the buying and selling of security is a morally charged and contested practice of governance

Controlling irregular migration: International human rights standards and the Hungarian legal framework

In the summer of 2015 Hungary constructed a 175 km long barbed-wire fence at its southern border with Serbia. New criminal offences and asylum procedures were introduced that limited access to refugee status determination and ignored agreed EU asylum policy, deterring and de facto preventing asylum seekers from entering Hungarian territory. This paper provides an analysis of these new measures, which criminalized asylum seekers, and the subsequent Hungarian policy in relation to the case law of the European Court of Human Rights – arguing that the Hungarian authorities excessively abused their discretion in implementing these new policies of immigration and border control

Police Culture and Police Leadership

Police leadership is a key focus for police practitioners and academics. However, little attention has been paid to the relationship between police leadership and police culture. In a policing field where, in rhetorical terms, leadership is presented as a means of limiting the damage caused by occupational culture, it is important for commentary to provide a critical focus upon the relationship between these two complex concepts. This chapter provides, by drawing on international policing literature and contexts, a conceptual and critical account of three main issues. First, whether or not police leaders can be conceptualized as having a particular cultural orientation. Second, by explaining the inherent conceptual tensions in the relationship. Finally, it explores the assumption that police culture represents a barrier to police leadership