2,621 research outputs found

    Towards a service-oriented e-infrastructure for multidisciplinary environmental research

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    Research e-infrastructures are considered to have generic and thematic parts. The generic part provids high-speed networks, grid (large-scale distributed computing) and database systems (digital repositories and data transfer systems) applicable to all research commnities irrespective of discipline. Thematic parts are specific deployments of e-infrastructures to support diverse virtual research communities. The needs of a virtual community of multidisciplinary envronmental researchers are yet to be investigated. We envisage and argue for an e-infrastructure that will enable environmental researchers to develop environmental models and software entirely out of existing components through loose coupling of diverse digital resources based on the service-oriented achitecture. We discuss four specific aspects for consideration for a future e-infrastructure: 1) provision of digital resources (data, models & tools) as web services, 2) dealing with stateless and non-transactional nature of web services using workflow management systems, 3) enabling web servce discovery, composition and orchestration through semantic registries, and 4) creating synergy with existing grid infrastructures

    A description of odd mass Xe and Te isotopes in the Interacting Boson-Fermion Model

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    Recent interest in spectroscopic factors for single-neutron transfer in low-spin states of the even-odd Xenon 125,127,129.131^{125,127,129.131}Xe and even-odd Tellurium, 123,125,127,129,131^{123,125,127,129,131}Te isotopes stimulated us to study these isotopes within the frame work of the Interacting Boson-Fermion Model. The fermion that is coupled to the system of bosons is taken to be in the positive parity 3s1/23s_{1/2}, 2d3/22d_{3/2}, 2d5/22d_{5/2}, 1g7/21g_{7/2} and in the negative 1h11/21h_{11/2} single-particle orbits, the complete 50-82 major shell. The calculated energies of low-spin energy levels of the odd isotopes are found to agree well with the experimental data. Also B(E2), B(M1) values and spectroscopic factors for single-neutron transfer are calculated and compared with experimental data.Comment: Submitted to Nuclear Physics

    A new limit on the Ultra-High-Energy Cosmic-Ray flux with the Westerbork Synthesis Radio Telescope

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    A particle cascade (shower) in a dielectric, for example as initiated by an ultra-high energy cosmic ray, will have an excess of electrons which will emit coherent \v{C}erenkov radiation, known as the Askaryan effect. In this work we study the case in which such a particle shower occurs in a medium just below its surface. We show, for the first time, that the radiation transmitted through the surface is independent of the depth of the shower below the surface when observed from far away, apart from trivial absorption effects. As a direct application we use the recent results of the NuMoon project, where a limit on the neutrino flux for energies above 102210^{22}\,eV was set using the Westerbork Synthesis Radio Telescope by measuring pulsed radio emission from the Moon, to set a limit on the flux of ultra-high-energy cosmic rays.Comment: Accepted for publication in Phys. Rev.

    Influence of grape rot on the contents of sulfur binding compounds in wine after automated optical grape sorting

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    In the last years, climate change has played an important role in some wine growing regions because of the increasing hazard of different kinds of bunch rot. Botrytis cinerea is the most important kind of rot on grapes. Beside sensory effects, this rot can influence the content of yeast nutrients, e.g. thiamine, in the must and thus affect the alcoholic fermentation. To get insight into the influence of Botrytis cinerea on the content of sulfur binding compounds formed during the fermentation process in wine, tons of grapes from the Mosel valley were sorted by an automated optical grape sorter, an innovative possibility of grape sorting, in 2011. Wine samples before sulfurisation of the four sorting fractions, namely control (unsorted berries), free-run (juice from opened berries), positive (healthy, intact berries) and negative (rotten berries) were analysed for the sulfur-binding compounds acetaldehyde, pyruvic acid, 2-oxoglutaric acid and for bound sulfur dioxide. The results show that acetaldehyde concentrations were not affected by rot, while pyruvic acid and 2-oxoglutaric acid levels were significantly higher in the negative fractions and lower in the positive fractions. Accordingly, bound sulfur levels were significantly higher in wines from the negative fraction. In conclusion, it could be shown that fractionation of the berries can efficiently help to reduce sulfur binding compounds in wine and thus reduce the addition of sulfur dioxide

    Cross section measurements on 61Cu for proton beam monitoring above 20 MeV

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    Introduction All experimental studies involving charged particle induced nuclear reactions require a precise knowledge of monitor reactions. A number of well described proton induced monitor reactions exist in the lower energy range [1], which is covered by most medical cyclotrons. Concerning proton energies above 20 MeV, however, the accuracy of the monitor reactions declines as cross section data becomes scarcer. Furthermore, the growing interest in precise determination of projectile energies by comparing of ratios of monitor reaction cross sections demands new measurements and evaluations of known data for high threshold monitor radionuclides. In this work cross section measurements on the formation of 61Cu were done and energy de-pendent radionuclide ratios were calculated. Material and Methods For investigation of the natCu(p,x)61Cu reaction copper foils of natural isotopic composition (Goodfellow Ltd.) were irradiated. The targets were of 10 and 20 μm thickness, having a diameter of 15 mm. Proton bombardments up to 45 MeV incident energy were done in the stacked-foil arrangement at the accelerator JULIC of the Nuclear Physics Institute (IKP) of the Forschungszentrum Jülich. In addition to an internal irradiation possibility the cyclotron is equipped with an external target station which was used for most experiments. It can adapt standard and slanting solid target holders and is equipped with a water cooled four sector collimator and additional helium cooling of the entry foil. Several irradiations were executed. In each stack, besides copper samples, aluminium absorbers and additional nickel monitor foils were also placed, the latter for the determination of the respective beam current. The produced radioactivity of 61Cu was analysed non-destructively using HPGe γ-ray detectors (EG&G Ortec). Results and Conclusion Reaction cross sections of the natCu(p,x)61Cu process up to 45 MeV were measured and com-pared with existing data from the literature (FIG. 2). Except for the data of Williams et al. our results are in good agreement, showing a maxi-mum of about 165 mbarn at 37.5 MeV proton energy. The overall uncertainty of the new cross section data is between 8 and 10 %. In FIG. 3, the excitation functions of the relevant monitor reactions on Cu are shown. In combination with the excitation function of the natCu(p,xn)62Zn reaction, isotope ratios were calculated which can be used for determination of the proton energy within a target stack in the energy range of 22–40 MeV as described by Piel et al. [3]. FIGURE 4 shows the cross section ratio in dependence of the proton energy. Above this energy, 65Zn could be used to generate isotope ratios for energy determination, although the long half-life (T½ = 244.3 d) of that radionuclide may be a problem. Additional cross section measurements are planned in order to further strengthen the data base of this potential monitor reaction. The results of this work shall be evaluated in the framework of an ongoing Coordinated Research Project of the IAEA

    An air shower array for LOFAR: LORA

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    LOFAR is a new form of radio telescope which can detect radio emission from air showers induced by very high-energy cosmic rays. It can also look for radio emission from particle cascades on the Moon induced by ultra high-energy cosmic rays or neutrinos. To complement the radio detection, we are setting up a small particle detector array LORA (LOfar Radboud Air shower array) within an area of ∼300\sim 300 m diameter in the LOFAR core. It will help in triggering and confirming the radio detection of air showers with the LOFAR antennas. In this paper, we present a short overview about LORA and discuss its current status.Comment: 10 pages (using article.cls), 6 figures, accepted for the proceedings of 22nd European Cosmic Ray Symposium, 3-6 August 2010, Finlan

    Patterns of the ground states in the presence of random interactions: nucleon systems

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    We present our results on properties of ground states for nucleonic systems in the presence of random two-body interactions. In particular we present probability distributions for parity, seniority, spectroscopic (i.e., in the laboratory framework) quadrupole moments and α\alpha clustering in the ground states. We find that the probability distribution for the parity of the ground states obtained by a two-body random ensemble simulates that of realistic nuclei: positive parity is dominant in the ground states of even-even nuclei while for odd-odd nuclei and odd-mass nuclei we obtain with almost equal probability ground states with positive and negative parity. In addition we find that for the ground states, assuming pure random interactions, low seniority is not favored, no dominance of positive values of spectroscopic quadrupole deformation, and no sign of α\alpha-cluster correlations, all in sharp contrast to realistic nuclei. Considering a mixture of a random and a realistic interaction, we observe a second order phase transition for the α\alpha-cluster correlation probability.Comment: 7 page

    Prediction of Psychological Distress Among Persons With Spinal Cord Injury or Acquired Brain Injury and Their Significant Others

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    Objectives: To identify intra- and interpersonal sociodemographic, injury-related, and psychological variables measured at admission of inpatient rehabilitation that predict psychological distress among dyads of individuals with spinal cord injury (SCI) or acquired brain injury (ABI) and their significant others (ie, individuals close to the individual with a disability, mostly family members) 6 months after discharge. Differences in predictors were investigated for persons with SCI or ABI and their significant others and were compared between diagnoses.Design: Prospective longitudinal study.Setting: Twelve Dutch rehabilitation centers.Participants: Dyads (N= 157) consisting of adults with SCI or ABI who were admitted to inpatient rehabilitation and their adult significant others.Interventions: Not applicable.Main Outcome Measures: Psychological distress (Hospital Anxiety and Depression Scale).Results: Sociodemographic and injury-related variables were not or were only weakly associated with psychological distress among individuals with SCI or ABI and their significant others 6 months after discharge. Bivariately, higher baseline psychological distress, lower scores on adaptive psychological characteristics (combination of self-efficacy, proactive coping, purpose in life, resilience), and higher scores on maladaptive psychological characteristics (combination of passive coping, neuroticism, appraisals of threat and loss) were related to higher psychological distress, as well as crosswise between individuals with SCI or ABI and their significant others, although less strongly. Combined prediction models showed that psychological distress among persons with SCI or ABI was predicted by education level of their significant other, their own baseline psychological distress, and their own maladaptive psychological characteristics (explained variance, 41.9%). Among significant others, only their own baseline psychological distress predicted psychological distress (explained variance, 40.4%). Results were comparable across diagnoses.Conclusions: Although a dyadic connection was shown, primarily one's own baseline psychological distress and psychological characteristics were important in the prediction of later psychological distress among both individuals with SCI or ABI and their significant others. Screening based on these variables could help to identify persons at risk for psychological distress. (C) 2020 by the American Congress of Rehabilitation Medicine</p
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