4,627 research outputs found

    Temporal and spectral variation of desert dust and biomass burning aerosol scenes from 1995?2000 using GOME

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    International audienceGlobal Ozone Monitoring Experiment (GOME) Absorbing Aerosol Index (AAI) and AAI-related residue data were used to investigate areas with UV-absorbing aerosols. Time series of regionally averaged residues show the seasonal variation and trends of aerosols and clouds in climatologically important parts of the globe. GOME spectra were used to study scenes containing specific types of aerosols. AAI data are specifically sensitive to biomass burning aerosols (BBA) and desert dust aerosols (DDA). Areas where these aerosols are regularly found were analysed to find spectral fingerprints in the ultraviolet (UV), visible and near-infrared (near-IR), to establish an aerosol type classification of BBA and DDA. Spectral residues are different for BBA and DDA, but over deserts the surface albedo is dominant beyond the UV and spectral residues cannot be used over land. Over oceans, about half of the BBA scenes show a very high reflectance that is never observed for DDA scenes. However, in the case of low reflectance scenes BBA and DDA cannot be distinguished. This is in part due to the microphysical and optical properties of biomass burning aerosols, which are highly variable in time, making it difficult to specify them spectrally as one type. Because of their high hygroscopicity BBA are often found in the presence of clouds, which disturb the spectrum of the scenes. Desert dust aerosols are much less hygroscopic and behave spectrally more uniformly

    Adapting and disseminating effective public health interventions in another country: towards a systematic approach.

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    Background: Public health interventions that have proven effective in one country, are often adapted and disseminated in other countries. However, the process by which effective interventions are chosen for adaptation and dissemination in another country is often not conducted systematically. Methods: We propose a more systematic approach and describe the main steps that have to be taken in the assessment of the usefulness of effective interventions in another national context. Results: The following steps are proposed. Step 0: Point out the most relevant areas in public health (this is a collaborative effort by policy makers, scientists and practitioners). Step 1: Identification of potentially effective interventions (through systematic literature searches). Step 2: Assessing the levels of evidence and grades of recommendation for adoption. Step 3: Can the results of the trials be generalized to the national situation? Step 4: Can the intervention be implemented in the national situation? Conclusion: A more systematic approach to the adaptation and dissemination can be adopted. The basic steps described should be worked out in more detail before they can be used in practice

    Caudal cervical vertebral morphological variation is not associated with clinical signs in Warmblood horses

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    Background Variation in equine caudal cervical spine morphology at C6 and C7 has high prevalence in Warmblood horses and is suspected to be associated with pain in a large mixed-breed group of horses. At present no data exist on the relationship between radiographic phenotype and clinical presentation in Warmblood horses in a case-control study. Objectives To establish the frequency of radiographically visible morphologic variation in a large group of Warmblood horses with clinical signs and compare this with a group without clinical signs. We hypothesised that occurrence of morphologic variation in the case group would not differ from the control group, indicating there is no association between clinical signs and morphologic variation. Study design Retrospective case-control. Methods Radiographic presence or absence of morphologic variation of cervical vertebrae C6 and C7 was recorded in case (n = 245) and control horses (n = 132). Case and control groups were compared by univariable Pearson's Chi-square and multivariable logistic regression for measurement variables age, sex, breed, degenerative joint disease and morphologic variation at C6 and C7. Odds ratio and confidence intervals were obtained. A P <= 0.05 was considered statistically significant. Results Morphologic variation at C6 and C7 (n = 108/377 = 28.6%; Cases 58/245 = 23.7%; Control 50/132 = 38%) was less frequent in horses with clinical signs in univariable testing (OR 0.48, 95% CI 0.3-0.8, P = 0.001). Age, sex, breed and degenerative joint disease were not retained in the final multivariable logistic regression step whereas morphologic variation remained significantly less present in horses with clinical signs. Main limitations Possible demographic differences between equine clinics. Conclusions Morphologic variation in the caudal cervical spine was detected more frequently in horses without clinical signs. Therefore, radiographic presence of such variation does not necessarily implicate the presence of clinical signs

    Coupling of a locally implanted rare-earth ion ensemble to a superconducting micro-resonator

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    We demonstrate the coupling of rare-earth ions locally implanted in a substrate (Gd3+^{3+} in Al2_{2}O3_{3}) to a superconducting NbN lumped-element micro-resonator. The hybrid device is fabricated by a controlled ion implantation of rare-earth ions in well-defined micron-sized areas, aligned to lithographically defined micro-resonators. The technique does not degrade the internal quality factor of the resonators which remain above 10510^{5}. Using microwave absorption spectroscopy we observe electron-spin resonances in good agreement with numerical modelling and extract corresponding coupling rates of the order of 11 MHz and spin linewidths of 50−6550 - 65 MHz.Comment: 4 pages, 2 Figure

    In-flight degradation correction of SCIAMACHY UV reflectances and Absorbing Aerosol Index

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    In this paper we study the close relationship between the radiometric calibration of a satellite instrument and the Absorbing Aerosol Index (AAI) derived from the observed Earth reflectance. Instrument degradation of the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument in the ultraviolet wavelength range is examined by analyzing time series of global means of the AAI, making use of the experience that the global mean should be more or less constant when instrument degradation is absent. The analysis reveals the magnitude of the (scan angle dependent) instrument degradation of SCIAMACHY and also shows that currently available correction techniques are not able to correct the instrument degradation in a sufficient manner. We therefore develop and introduce a new method for degradation correction, which is based on the analysis of the time evolution of the global mean reflectance. Seasonal variations in the global mean reflectance, which mainly result from seasonal variations in scattering geometry and global cloud coverage, are separated from the time series in order to isolate the instrument degradation. Finally, we apply the derived reflectance correction factors to the SCIAMACHY reflectances and calculate the AAI to find that the effects of instrument degradation are reduced to within the 0.1 index point level. The derived AAI is also compared with the AAI based on other correction techniques. The proposed in-flight reflectance degradation correction method performs best in all aspects. © 2012 by the American Geophysical Union

    A Lattice Boltzmann Model for Squirmers

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    The squirmer is a simple yet instructive model for microswimmers, which employs an effective slip velocity on the surface of a spherical swimmer to describe its self-propulsion. We solve the hydrodynamic flow problem with the lattice Boltzmann (LB) method, which is well-suited for time-dependent problems involving complex boundary conditions. Incorporating the squirmer into LB is relatively straight-forward, but requires an unexpectedly fine grid resolution to capture the physical flow fields and behaviors accurately. We demonstrate this using four basic hydrodynamic tests: Two for the far-field flow---accuracy of the hydrodynamic moments and squirmer-squirmer interactions---and two that require the near field to be accurately resolved---a squirmer confined to a tube and one scattering off a spherical obstacle---which LB is capable of doing down to the grid resolution. We find good agreement with (numerical) results obtained using other hydrodynamic solvers in the same geometries and identify a minimum required resolution to achieve this reproduction. We discuss our algorithm in the context of other hydrodynamic solvers and present an outlook on its application to multi-squirmer problems.Comment: 9 pages, 7 figure

    Minimal important change in physical function in trauma patients:a study using the short musculoskeletal function assessment

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    PURPOSE: The Short Musculoskeletal Function Assessment (SMFA) questionnaire can be used to evaluate physical functioning in patients with traumatic injuries. It is not known what change in score reflects a meaningful change to patients. The aim was to determine minimal important change (MIC) values of the subscales (0-100) of the Dutch SMFA-NL in a sample of patients with a broad range of injuries. METHODS: Patients between 18 and 65 years of age completed the SMFA-NL and the Global Rating of Effect (GRE) questions at 6-week and 12-month post-injury. Anchor-based MIC values were calculated using univariable logistic regression analyses. RESULTS: A total of 225 patients were included (response rate 67%). The MIC value of the Upper Extremity Dysfunction (UED) subscale was 8 points, with a misclassification rate of 43%. The Lower Extremity Dysfunction subscale MIC value was 14 points, with a misclassification rate of 29%. The MIC value of the Problems with Daily Activities subscale was 25 points, with a misclassification rate of 33%. The MIC value of the Mental and Emotional Problems (MEP) subscale was 7 points, with a misclassification rate 37%. CONCLUSION: MIC values of the SMFA-NL were determined. The MIC values aid interpreting whether a change in physical functioning can be considered clinically important. Due to the considerable rates of misclassification, the MIC values of the UED and MEP subscales should be used with caution

    Live and let live:Residents' perspectives on alcohol and tobacco (mis)use in residential care facilities

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    Background Alcohol and tobacco use could cause health problems in older adults. Older adults who become in need of 24/7 care due to physical and/or neurological disabilities may need to move to a Residential Care Facility (RCF). RCFs aim to provide person-centred care (PCC) to enhance quality of life (QoL) of residents. Objectives This study aims to explore perspectives of residents on alcohol and tobacco use, which is essential to provide PCC. Methods A qualitative research design was chosen, and semi-structured interviews were conducted. Residents who use alcohol and/or tobacco and those who do not use these substances were purposively selected in two organisations on two types of units: psychogeriatric units and units providing care for residents with mainly physical disabilities. The results were analysed using thematic analysis. Results Thematic analysis resulted in five themes: Current use and self-reflection, knowledge and attitudes, addiction or habit, policies and availability, dependency versus autonomy. Conclusion Residents in this study value their autonomy regarding alcohol and tobacco use. They experience dependency on their (in)formal caregivers to use these substances and acknowledge that their use could cause a nuisance to others, challenging the ability of caregivers to implement PCC. Future research could assess how to integrate providing PCC to residents by offering choices and autonomy, while considering the addictive component of these substances, health and safety risks for all

    Connectivity between migrating and landlocked populations of a diadromous fish species investigated using otolith microchemistry

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    Smelt Osmerus eperlanus has two different life history strategies in the Netherlands. The migrating population inhabits the Wadden Sea and spawns in freshwater areas. After the closure of the Afsluitdijk in 1932, part of the smelt population became landlocked. The fresh water smelt population has been in severe decline since 1990, and has strongly negatively impacted the numbers of piscivorous water birds relying on smelt as their main prey. The lakes that were formed after the dike closure, IJsselmeer and Markermeer have been assigned as Natura 2000 sites, based on their importance for (among others) piscivorous water birds. Because of the declining fresh water smelt population, the question arose whether this population is still supported by the diadromous population. Opportunities for exchange between fresh water and the sea are however limited to discharge sluices. The relationship between the diadromous and landlocked smelt population was analysed by means of otolith microchemistry. Our interpretation of otolith strontium (88Sr) patterns from smelt specimens collected in the fresh water area of Lake IJsselmeer and Markermeer, compared to those collected in the nearby marine environment, is that there is currently no evidence for a substantial contribution from the diadromous population to the spawning stock of the landlocked population

    Nasal hyperreactivity and inflammation in allergic rhinitis

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    The history of allergic disease goes back to 1819, when Bostock described his own ‘periodical affection of the eyes and chest’, which he called ‘summer catarrh’. Since they thought it was produced by the effluvium of new hay, this condition was also called hay fever. Later, in 1873, Blackley established that pollen played an important role in the causation of hay fever. Nowadays, the definition of allergy is ‘An untoward physiologic event mediated by a variety of different immunologic reactions’. In this review, the term allergy will be restricted to the IgE-dependent reactions. The most important clinical manifestations of IgE-dependent reactions are allergic conjunctivitis, allergic rhinitis, allergic asthma and atopic dermatitis. However, this review will be restricted to allergic rhinitis. The histopathological features of allergic inflammation involve an increase in blood flow and vascular permeability, leading to plasma exudation and the formation of oedema. In addition, a cascade of events occurs which involves a variety of inflammatory cells. These inflammatory cells migrate under the influence of chemotactic agents to the site of injury and induce the process of repair. Several types of inflammatory cells have been implicated in the pathogenesis of allergic rhinitis. After specific or nonspecific stimuli, inflammatory mediators are generated from cells normally found in the nose, such as mast cells, antigen-presenting cells and epithelial cells (primary effector cells) and from cells recruited into the nose, such as basophils, eosinophils, lymphocytes, platelets and neutrophils (secondary effector cells). This review describes the identification of each of the inflammatory cells and their mediators which play a role in the perennial allergic processes in the nose of rhinitis patients
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