60 research outputs found

    User-Centered Evaluation of Adaptive and Adaptable Systems

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    Adaptive and adaptable systems provide tailored output to various users in various contexts. While adaptive systems base their output on implicit inferences, adaptable systems use explicitly provided information. Since the presentation or output of these systems is adapted, standard user-centered evaluation methods do not produce results that can be easily generalized. This calls for a reflection on the appropriateness of standard evaluation methods for user-centered evaluations of these systems. We have conducted a literature review to create an overview of the methods that have been used. When reviewing the empirical evaluation studies we have, among other things, focused on the variables measured and the implementation of results in the (re)design process. The goal of our review has been to compose a framework for user-centered evaluation. In the next phase of the project, we intend to test some of the most valid and feasible methods with an adaptive or adaptable system

    First geolocator tracks of Swedish red-necked phalaropes reveal the Scandinavia-Arabian Sea connection

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    We studied migration and wintering patterns of a wader with a pelagic lifestyle during the non-breeding period, the rednecked phalarope Phalaropus lobatus . Using light-level geolocation, we obtained three full annual tracks and one autumn migration track of male red-necked phalaropes caught during breeding in Scandinavia. Th ese tracks confi rmed expectations that individuals from the Scandinavian population winter in the Arabian Sea. Migration was accomplished in two to four migration leaps, staging for a few days in the Gulf of Finland (autumn) or the southern Baltic Sea (spring) and for up to a month in or near the Black and Caspian Sea (autumn and spring). In addition, travel speeds suggested that only the fl ights between the Baltic and Black/Caspian Sea are non-stop, and thus the birds seem to make additional short stops during the other flights. Stopover time in the Black/Caspian Sea is only 8 – 10 d in spring but up to 36 d in autumn, which is longer than expected if only used for pre-migratory fattening to cover the ca 2000 km to the Gulf of Oman. After entering the Arabian Sea via the Gulf of Oman, birds dispersed over the entire presumed winter range. Winter movements appear to correspond to the spatio-temporal patterns in primary production linked to seasonally changing monsoon winds. Th ese are not only the first tracks of Scandinavian red-necked phalaropes, but also the fi rst seabird tracks in the Arabian Sea, one of the most productive and dynamic marine areas on the planet

    An outbreak of ST307 extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae in a rehabilitation center: An unusual source and route of transmission

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    Objective: Nosocomial outbreaks due to multidrug-resistant microorganisms in rehabilitation centers have rarely been reported. We report an outbreak of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae (ESBL-K. pneumoniae) on a single ward in a rehabilitation center in Rotterdam, The Netherlands.Design: Outbreak description.Setting: A 40-bed ward of a rehabilitation center in the Netherlands.Methods: In October 2016, 2 patients were found to be colonized by genetically indistinguishable ESBL-K. pneumoniae isolates. Therefore, an outbreak management team was installed, by whom a contact tracing plan was made. In addition to general outbreak measures, specific measures were formulated to allow continuation of the rehabilitation process. Also, environmental cultures were taken. Multiple-locus variable-number tandem-repeat analysis and amplification fragment-length polymorphism were used to determine strain relatedness. Selected isolates were subjected to whole-genome multilocus sequence typing.Results: The outbreak lasted 8 weeks. In total, 14 patients were colonized with an ESBL-K. pneumoniae, of whom 11 patients had an isolate belonging to

    The role of tunneling in enzyme catalysis of C–H activation

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    AbstractRecent data from studies of enzyme catalyzed hydrogen transfer reactions implicate a new theoretical context in which to understand C–H activation. This is much closer to the Marcus theory of electron transfer, in that environmental factors influence the probability of effective wave function overlap from donor to acceptor atoms. The larger size of hydrogen and the availability of three isotopes (H, D and T) introduce a dimension to the kinetic analysis that is not available for electron transfer. This concerns the role of gating between donor and acceptor atoms, in particular whether the system in question is able to tune distance between reactants to achieve maximal tunneling efficiency. Analysis of enzyme systems is providing increasing evidence of a role for active site residues in optimizing the inter-nuclear distance for nuclear tunneling. The ease with which this optimization can be perturbed, through site-specific mutagenesis or an alteration in reaction conditions, is also readily apparent from an analysis of the changes in the temperature dependence of hydrogen isotope effects

    A Migratory Divide Among Red-Necked Phalaropes in the Western Palearctic Reveals Contrasting Migration and Wintering Movement Strategies

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    Non-breeding movement strategies of migratory birds may be expected to be flexibly adjusted to the distribution and quality of habitat, but only few studies compare movement strategies between populations using distinct migration routes and wintering areas. In thisour study, individual movement strategies of Rred-necked pPhalaropes Phalaropus lobatus, a long-distance migratory wader using saline waters in the non-breeding period, were studied using light-level geolocators. Results revealed the existence of two populations with distinct migration routes and wintering areas: one breeding in the north-eastern North Atlantic and migrating ca. 10,000 km oversea to the tropical eastern Pacific Ocean and the other breeding in Fennoscandia and Russia migrating ca. 6,000 km – largely over land – to the Arabian Sea (Indian Ocean). In line with our expectations, the transoceanic migration between the North Atlantic and the Pacific was associated with proportionately longer wings, a more even spread of stopovers in autumn and a higher migration speed in spring compared to the migration between Fennoscandian-Russian breeding grounds and the Arabian Sea. In the wintering period, birds wintering in the Pacific were stationaryresided in roughly a singlethe same area, whereas individuals wintering in the Arabian Sea showed individually consistent movementsd extensively between different areas, reflecting differences in spatio-temporal variation in primary productivity between the two wintering areas. Our study is unique in showing how habitat distribution shapes movement strategies over the entire non-breeding period within a species.Peer reviewe

    The diagnostic value of CRP, IL-8, PCT, and sTREM-1 in the detection of bacterial infections in pediatric oncology patients with febrile neutropenia

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    In this study, we evaluated C-reactive protein (CRP), interleukin (IL)-8, procalcitonin (PCT), and soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) as predictors for bacterial infection in febrile neutropenia, plus their usefulness in febrile neutropenia during chemotherapy-induced gastrointestinal mucositis. Plasma was obtained from pediatric oncology patients at presentation with febrile neutropenia (n = 43) and 24-48 h later (n = 17). The patients were classified as having or not having a bacterial infection. Plasma was also obtained of patients in the absence and in the presence of mucositis (n = 26). At presentation with febrile neutropenia, median IL-8 and PCT levels were significantly increased in patients with a bacterial infection, in contrast to CRP and sTREM-1. IL-8 was the most sensitive marker for the early detection of bacterial infection, in combination with clinical parameters or PCT the sensitivity reached 100%. After 24-48 h, only PCT was significantly elevated during bacterial infection. IL-8 levels were significantly increased during mucositis. Mucositis did not cause considerable changes in PCT levels. IL-8 is the most useful marker for the early detection of bacterial infections, compared with CRP, PCT, and sTREM-1. IL-8 in combination with clinical parameters or PCT might be even more useful. Gastrointestinal mucositis alone does not affect PCT levels, in contrast to IL-8 levels, and therefore, PCT might be more useful for the detection of bacterial infections during mucositis than IL-8

    Effects of acute tryptophan depletion on affective processing in first-degree relatives of depressive patients and controls after exposure to uncontrollable stress

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    Rationale Individuals with a family history of depression may be more likely to develop depression due to an innate vulnerability of their serotonergic system. However, even though serotonergic vulnerability may constitute a risk factor in the development of depression, it does not seem to be sufficient to cause a depressive episode. Based on previous data, it is suggested that stress may be a mediating factor. Objectives This study examined the role of serotonin (5-HT) in stress coping in individuals with or without a family history of depression. Materials and methods Nineteen healthy first-degree relatives of depressive patients (FH+) and 19 healthy controls without a family history of depression (FH-) were tested in a double-blind placebo-controlled design for affective processing under acute stress exposure, following acute tryptophan depletion (ATD) or placebo. Results Significant negative effects were found of stress on affective processing in FH- and FH+. In addition, FH- responded slower to positive words after stress only following ATD, whereas FH+ responded marginally slower under stress already after placebo and before stress following ATD. Conclusion Acute stress exposure reduces positive affective bias; supporting the role of stress as an important predecessor in the development of depression. Furthermore, FH+ may be more susceptible than FH- to the negative effects of stress as well as to the negative effects of ATD. The results support the assumption that the 5-HT system is involved in stress resilience and may be more vulnerable in first-degree relatives of depression

    Discovery of very high energy gamma-ray emission coincident with molecular clouds in the W28 (G6.4-0.1) field

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    We observed the W28 field (for ~40 h) at Very High Energy (VHE) gamma-ray energies (E>0.1 TeV) with the H.E.S.S. Cherenkov telescopes. A reanalysis of EGRET E>100 MeV data was also undertaken. Results from the NANTEN 4m telescope Galactic plane survey and other CO observations have been used to study molecular clouds. We have discovered VHE gamma-ray emission (HESSJ1801-233) coincident with the northeastern boundary of W28, and a complex of sources (HESSJ1800-240A, B and C) ~0.5 deg south of W28, in the Galactic disc. The VHE differential photon spectra are well fit by pure power laws with indices Gamma~2.3 to 2.7. The NANTEN ^{12}CO(J=1-0) data reveal molecular clouds positionally associating with the VHE emission, spanning a ~15 km s^{-1} range in local standard of rest velocity. The VHE/molecular cloud association could indicate a hadronic origin for HESSJ1801-233 and HESSJ1800-240, and several cloud components in projection may contribute to the VHE emission. The clouds have components covering a broad velocity range encompassing the distance estimates for W28 (~2 kpc), and extending up to ~4 kpc. Assuming a hadronic origin, and distances of 2 and 4 kpc for cloud components, the required cosmic ray density enhancement factors (with respect to the solar value) are in the range ~10 to ~30. If situated at 2 kpc distance, such cosmic ray densities may be supplied by a SNR like W28. Additionally and/or alternatively, particle acceleration may come from several catalogued SNRs and SNR candidates, the energetic ultra compact HII region W28A2, and the HII regions M8 and M20 along with their associated open clusters. Further sub-mm observations would be recommended to probe in detail the dynamics of the molecular clouds at velocites >10 km s^{-1}, and their possible connection to W28.Comment: 10 pages, 4 figures. Accepted for publication in Astronomy & Astrophysics. (Abstract shortened
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