48,254 research outputs found

    The actors that shape the knowledge, attitudes and behaviour of Maltese youth

    Get PDF
    Not much is known about the environmental knowledge, attitudes and actions of young people in the Maltese islands. The main actors that are responsible for the acquisition and development of environmental perspectives in young people in Malta are also not well known. There is as yet, little understanding of the extent to which these actors are fostering a sense of environmental responsibility and a greater commitment towards sustainable development. A mixed method research methodology was employed to address this knowledge gap that included an extended questionnaire distributed to students in the post secondary age range and a number of focus groups to provide a more in-depth study of some of the issues arising from the questionnaire analyses. The focus groups allowed young people to frame their responses in their own words. This paper focuses on the results of the quantitative study. The data from the quantitative analyses indicates that students are more knowledgeable about the Global Environment than about the Local Environment, and that students receive most information from School, Television and the Internet. The sources of environmental information which were perceived by young people as being the most reliable included School, Books and the Internet. The overall attitude of students towards the environment appears to be strongly positive, however students seem to perform little positive actions towards the environment. Year group, Age and Gender were found to have a statistically significant effect on knowledge; Father’s work was found to have a statistically significant effect on attitude and Age was found to have a significant effect on behavior.peer-reviewe

    Determining Ratios of WIMP-Nucleon Cross Sections from Direct Dark Matter Detection Data

    Full text link
    Weakly Interacting Massive Particles (WIMPs) are one of the leading candidates for Dark Matter. So far the usual procedure for constraining the WIMP-nucleon cross sections in direct Dark Matter detection experiments have been to fit the predicted event rate based on some model(s) of the Galactic halo and of WIMPs to experimental data. One has to assume whether the spin-independent (SI) or the spin-dependent (SD) WIMP-nucleus interaction dominates, and results of such data analyses are also expressed as functions of the as yet unknown WIMP mass. In this article, I introduce methods for extracting information on the WIMP-nucleon cross sections by considering a general combination of the SI and SD interactions. Neither prior knowledge about the local density and the velocity distribution of halo WIMPs nor about their mass is needed. Assuming that an exponential-like shape of the recoil spectrum is confirmed from experimental data, the required information are only the measured recoil energies (in low energy ranges) and the number of events in the first energy bin from two or more experiments.Comment: 33 pages, 20 eps figures; v2: typos fixed, references added and updated, revised version for publicatio

    On Approximating the Number of kk-cliques in Sublinear Time

    Full text link
    We study the problem of approximating the number of kk-cliques in a graph when given query access to the graph. We consider the standard query model for general graphs via (1) degree queries, (2) neighbor queries and (3) pair queries. Let nn denote the number of vertices in the graph, mm the number of edges, and CkC_k the number of kk-cliques. We design an algorithm that outputs a (1+ε)(1+\varepsilon)-approximation (with high probability) for CkC_k, whose expected query complexity and running time are O\left(\frac{n}{C_k^{1/k}}+\frac{m^{k/2}}{C_k}\right)\poly(\log n,1/\varepsilon,k). Hence, the complexity of the algorithm is sublinear in the size of the graph for Ck=ω(mk/21)C_k = \omega(m^{k/2-1}). Furthermore, we prove a lower bound showing that the query complexity of our algorithm is essentially optimal (up to the dependence on logn\log n, 1/ε1/\varepsilon and kk). The previous results in this vein are by Feige (SICOMP 06) and by Goldreich and Ron (RSA 08) for edge counting (k=2k=2) and by Eden et al. (FOCS 2015) for triangle counting (k=3k=3). Our result matches the complexities of these results. The previous result by Eden et al. hinges on a certain amortization technique that works only for triangle counting, and does not generalize for larger cliques. We obtain a general algorithm that works for any k3k\geq 3 by designing a procedure that samples each kk-clique incident to a given set SS of vertices with approximately equal probability. The primary difficulty is in finding cliques incident to purely high-degree vertices, since random sampling within neighbors has a low success probability. This is achieved by an algorithm that samples uniform random high degree vertices and a careful tradeoff between estimating cliques incident purely to high-degree vertices and those that include a low-degree vertex

    Deriving a systematic approach to changeable manufacturing system design

    Get PDF
    It has long been argued that Factories are long life and complex products. The complexity of designing factories, and their underlying manufacturing systems, is further amplified when dealing with continuously changing customer demands. At the same time, due to research fragmentation, little if any scientific explanations are available supporting and exploiting the paradigm that "factories are products". In order to address this weakness, this paper presents research results arising from a comparative analysis of systematic "product design" and "manufacturing system design" approaches. The contribution emerging from this research is an integrated systematic design approach to changeable manufacturing systems, based on scientific concepts founded upon product design theories, and is explained through a case study in the paper. This research is part of collaboration between the CERU University of Malta and IAO Fraunhofer aimed at developing a digital decision support tool for planning changeable manufacturing systems.peer-reviewe

    Deaths certified as asthma and use of medical services: A national case-control study

    Get PDF
    This is an open access publication. The official published version can be accessed from the link below.Background: Studies have linked asthma death to either increased or decreased use of medical services. Methods: A population based case-control study of asthma deaths in 1994–8 was performed in 22 English, six Scottish, and five Welsh health authorities/boards. All 681 subjects who died were under the age of 65 years with asthma in Part I on the death certificates. After exclusions, 532 hospital controls were matched to 532 cases for age, district, and date of asthma admission/death. Data were extracted blind from primary care records. Results: The median age of the subjects who died was 53 years; 60% of cases and 64% of controls were female. There was little difference in outpatient attendance (55% and 55%), hospital admission for asthma (51% and 54%), and median inpatient days (20 days and 15 days) in the previous 5 years. After mutual adjustment and adjustment for sex, using conditional logistic regression, three variables were independently associated with asthma death: fewer general practice contacts (odds ratio 0.82 (95% confidence interval (CI) 0.74 to 0.91) per 5 contacts) in the previous year, more home visits (1.14 (95% CI 1.08 to 1.21) per visit) in the previous year, and fewer peak expiratory flow recordings (0.83 (95% CI 0.74 to 0.92) per occasion) in the previous 3 months. These associations were similar after adjustment for markers of severity, psychosocial factors, systemic steroids, short acting bronchodilators and antibiotics, although the association with peak flow was weakened and just lost significance. Conclusion: Asthma death is associated with less use of primary care services. Both practice and patient factors may be involved and a better understanding of these may offer possibilities for reducing asthma death.This study was funded jointly between the National Research and Development Asthma Management Programme (contract number AM1/ 05/002) and the National Asthma Campaign through a grant from Glaxo Wellcome (now GlaxoSmithKline)

    Constriction size distributions of granular filters: a numerical study

    Get PDF
    The retention capability of granular filters is controlled by the narrow constrictions connecting the voids within the filter. The theoretical justification for empirical filter rules used in practice includes consideration of an idealised soil fabric in which constrictions form between co-planar combinations of spherical filter particles. This idealised fabric has not been confirmed by experimental or numerical observations of real constrictions. This paper reports the results of direct, particle-scale measurement of the constriction size distribution (CSD) within virtual samples of granular filters created using the discrete-element method (DEM). A previously proposed analytical method that predicts the full CSD using inscribed circles to estimate constriction sizes is found to poorly predict the CSD for widely graded filters due to an over-idealisation of the soil fabric. The DEM data generated are used to explore quantitatively the influence of the coefficient of uniformity, particle size distribution and relative density of the filter on the CSD. For a given relative density CSDs form a narrow band of similarly shaped curves when normalised by characteristic filter diameters. This lends support to the practical use of characteristic diameters to assess filter retention capability

    Logic programming in the context of multiparadigm programming: the Oz experience

    Full text link
    Oz is a multiparadigm language that supports logic programming as one of its major paradigms. A multiparadigm language is designed to support different programming paradigms (logic, functional, constraint, object-oriented, sequential, concurrent, etc.) with equal ease. This article has two goals: to give a tutorial of logic programming in Oz and to show how logic programming fits naturally into the wider context of multiparadigm programming. Our experience shows that there are two classes of problems, which we call algorithmic and search problems, for which logic programming can help formulate practical solutions. Algorithmic problems have known efficient algorithms. Search problems do not have known efficient algorithms but can be solved with search. The Oz support for logic programming targets these two problem classes specifically, using the concepts needed for each. This is in contrast to the Prolog approach, which targets both classes with one set of concepts, which results in less than optimal support for each class. To explain the essential difference between algorithmic and search programs, we define the Oz execution model. This model subsumes both concurrent logic programming (committed-choice-style) and search-based logic programming (Prolog-style). Instead of Horn clause syntax, Oz has a simple, fully compositional, higher-order syntax that accommodates the abilities of the language. We conclude with lessons learned from this work, a brief history of Oz, and many entry points into the Oz literature.Comment: 48 pages, to appear in the journal "Theory and Practice of Logic Programming

    Exploring the phase space of multiple states in highly turbulent Taylor-Couette flow

    Get PDF
    We investigate the existence of multiple turbulent states in highly turbulent Taylor-Couette flow in the range of Ta=1011\mathrm{Ta}=10^{11} to 910129\cdot10^{12}, by measuring the global torques and the local velocities while probing the phase space spanned by the rotation rates of the inner and outer cylinder. The multiple states are found to be very robust and are expected to persist beyond Ta=1013\mathrm{Ta}=10^{13}. The rotation ratio is the parameter that most strongly controls the transitions between the flow states; the transitional values only weakly depend on the Taylor number. However, complex paths in the phase space are necessary to unlock the full region of multiple states. Lastly, by mapping the flow structures for various rotation ratios in a Taylor-Couette setup with an equal radius ratio but a larger aspect ratio than before, multiple states were again observed. Here, they are characterized by even richer roll structure phenomena, including, for the first time observed in highly turbulent TC flow, an antisymmetrical roll state.Comment: 9 pages, 7 figure
    corecore