5,783 research outputs found

    Governing locally for sustainability: public and private organizations’ perspective in surf tourism at Aljezur, Costa Vicentina, Portugal

    Get PDF
    This study explores how a rural municipality of low population density and strong tourism intensity for the practice of recreational activities can exert a sustainable collective action in the policies and strategies of planning and development of local tourism. The study focuses on the case study of the municipality of Aljezur, in Portugal, and is applied to a dominant tourism-recreational activity, surfing. Based on a survey of relevant stakeholders, namely private and public organizations, it was possible to obtain indicators of local environmental, economic and social convergence. These allowed elaborating a proposal for a municipal sustainable management charter of the surfing tourism in the region. The conception of this charter and the consequent strategies moves the management of local tourism destinations to higher levels of institutional sustainability.info:eu-repo/semantics/acceptedVersio

    A guided search non-dominated sorting genetic algorithm for the multi-objective university course timetabling problem

    Get PDF
    Copyright @ Springer-Verlag Berlin Heidelberg 2011.The university course timetabling problem is a typical combinatorial optimization problem. This paper tackles the multi-objective university course timetabling problem (MOUCTP) and proposes a guided search non-dominated sorting genetic algorithm to solve the MOUCTP. The proposed algorithm integrates a guided search technique, which uses a memory to store useful information extracted from previous good solutions to guide the generation of new solutions, and two local search schemes to enhance its performance for the MOUCTP. The experimental results based on a set of test problems show that the proposed algorithm is efficient for solving the MOUCTP

    A determination of the average up-down, strange and charm quark masses from Nf=2+1+1N_f=2+1+1

    Get PDF
    We present a lattice QCD determination of the average up-down, strange and charm quark masses based on simulations performed by the European Twisted Mass Collaboration with Nf=2+1+1N_f = 2 + 1 + 1 dynamical fermions. We simulated at three different values of the lattice spacing, the smallest being approximately 0.06fm0.06fm, and with pion masses as small as 210MeV210 \text{MeV}. Our results are: mud(2GeV)=3.70(17)MeVm_{ud}(2\text{GeV})=3.70(17)\text{MeV}, ms(2GeV)=99.2(3.9)MeVm_s(2\text{GeV})=99.2(3.9)\text{MeV}, mc(mc)=1.350(49)GeVm_c(m_c)=1.350(49)\text{GeV}, ms/mud=26.64(30)m_s/m_{ud}=26.64(30) and mc/ms=11.65(12)m_c/m_s=11.65(12)

    K^0-\bar{K}^0 mixing in the Standard Model from Nf=2+1+1 Twisted Mass Lattice QCD

    Full text link
    We present preliminary results at {\beta} = 1.95 (a = 0.077 fm) on the first unquenched N_f=2+1+1 lattice computation of the B_K parameter which controls the neutral kaon oscillations in the Standard Model. Using N_f=2+1+1 maximally twisted sea quarks and Osterwalder-Seiler valence quarks we achieve O(a) improvement and a continuum-like renormalization pattern for the four-fermion operator. Our results are extrapolated/interpolated to the physical light/strange quark mass but not yet to the continuum limit. The computation of the relevant renormalization constants is performed non perturbatively in the RI'-MOM scheme using dedicated simulations with N_f=4 degenerate sea quark flavours produced by the ETM collaboration. We get B_K^{RGI} (a = 0.077) = 0.747(18), which when compared to our previous unquenched N_f=2 determination and most of the existing results, suggests a rather weak B_K^{RGI} dependence on the number of dynamical flavours. We are at the moment analysing lattice data at two additional {\beta} values which will allow us to perform an extrapolation to the continuum limit.Comment: 7 pages, 8 figures, Proceedings of Lattice 2011, XXIX International Symposium on Lattice Field Theory, Squaw Valley, Lake Tahoe, Californi

    Three-nucleon mechanisms in photoreactions

    Full text link
    The 12^{12}C(γ,ppn)(\gamma,ppn) reaction has been measured for Eγ_{\gamma}=150-800 MeV in the first study of this reaction in a target heavier than 3^3He. The experimental data are compared to a microscopic many body calculation. The model, which predicts that the largest contribution to the reaction arises from final state interactions following an initial pion production process, overestimates the measured cross sections and there are strong indications that the overestimate arises in this two-step process. The selection of suitable kinematic conditions strongly suppresses this two-step contribution leaving cross sections in which up to half the yield is predicted to arise from the absorption of the photon on three interacting nucleons and which agree with the model. The results indicate (γ,3N)(\gamma,3N) measurements on nuclei may be a valuable tool for obtaining information on the nuclear three-body interaction.Comment: 5 pages, 3 figure

    A combinatorial method for the evaluation of yield of fault-tolerant systems-on-chip

    Get PDF
    In this paper we develop a combinatorial method for the evaluation of yield of fault-tolerant systems-on-chip. The method assumes that defects are produced according to a model in which defects are lethal and affect given components of the system following a distribution common to all defects. The distribution of the number of defects is arbitrary. The method is based on the formulation of the yield as 1 minus the probability that a given boolean function with multiple-valued variables has value 1. That probability is computed by analyzing a ROMDD (reduced ordered multiple-valuedecision diagram) representation of the function. For efficiency reasons, we first build a coded ROBDD (reduced ordered binary decision diagram) representation of the function and then transform that coded ROBDD into the ROMDD required by the method. We present numerical experiments showing that the method is able to cope with quite large systems in moderate CPU times.Postprint (published version

    Weak and Compact Radio Emission in Early High-Mass Star Forming Regions: II. The Nature of the Radio Sources

    Get PDF
    In this study we analyze 70 radio continuum sources associated with dust clumps and considered to be candidates for the earliest stages of high-mass star formation. The detection of these sources was reported by Rosero et al. (2016), who found most of them to show weak (<{\scriptstyle <}1 mJy) and compact (< {\scriptstyle <}\,0.6′′^{\prime \prime}) radio emission. Herein, we used the observed parameters of these sources to investigate the origin of the radio continuum emission. We found that at least ∼30%\sim 30\% of these radio detections are most likely ionized jets associated with high-mass protostars, but for the most compact sources we cannot discard the scenario that they represent pressure-confined HII regions. This result is highly relevant for recent theoretical models based on core accretion that predict the first stages of ionization from high-mass stars to be in the form of jets. Additionally, we found that properties such as the radio luminosity as a function of the bolometric luminosity of ionized jets from low and high-mass stars are extremely well-correlated. Our data improve upon previous studies by providing further evidence of a common origin for jets independently of luminosity.Comment: Accepted for publication in the Ap

    Weak and Compact Radio Emission in Early High-Mass Star Forming Regions: I. VLA Observations

    Get PDF
    We present a high sensitivity radio continuum survey at 6 and 1.3 \,cm using the Karl G. Jansky Very Large Array towards a sample of 58 high-mass star forming regions. Our sample was chosen from dust clumps within infrared dark clouds with and without IR sources (CMC-IRs, CMCs, respectively), and hot molecular cores (HMCs), with no previous, or relatively weak radio continuum detection at the 1 1\,mJy level. Due to the improvement in the continuum sensitivity of the VLA, this survey achieved map rms levels of ∼\sim 3-10 μ\muJy beam−1^{-1} at sub-arcsecond angular resolution. We extracted 70 centimeter continuum sources associated with 1.2 \,mm dust clumps. Most sources are weak, compact, and are prime candidates for high-mass protostars. Detection rates of radio sources associated with the mm dust clumps for CMCs, CMC-IRs and HMCs are 6%\%, 53%\% and 100%\%, respectively. This result is consistent with increasing high-mass star formation activity from CMCs to HMCs. The radio sources located within HMCs and CMC-IRs occur close to the dust clump centers with a median offset from it of 12,000 \,AU and 4,000 \,AU, respectively. We calculated 5 - 25 \,GHz spectral indices using power law fits and obtain a median value of 0.5 (i.e., flux increasing with frequency), suggestive of thermal emission from ionized jets. In this paper we describe the sample, observations, and detections. The analysis and discussion will be presented in Paper II.Comment: Accepted for publication in the ApJ
    • …
    corecore