1,561 research outputs found

    Imaging dielectric relaxation in nanostructured polymers by frequency modulation electrostatic force microscopy

    Get PDF
    We have developed a method for imaging the temperature-frequency dependence of the dynamics of nanostructured polymer films with spatial resolution. This method provides images with dielectric compositional contrast well decoupled from topography. Using frequency-modulation electrostatic-force-microscopy, we probe the local frequency-dependent (0.1–100 Hz) dielectric response through measurement of the amplitude and phase of the force gradient in response to an oscillating applied electric field. When the phase is imaged at fixed frequency, it reveals the spatial variation in dielectric losses, i.e., the spatial variation in molecular/dipolar dynamics, with 40 nm lateral resolution. This is demonstrated by using as a model system; a phase separated polystyrene/polyvinyl-acetate (PVAc) blend. We show that nanoscale dynamic domains of PVAc are clearly identifiable in phase images as those which light-up in a band of temperature, reflecting the variations in the molecular/dipolar dynamics approaching the glass transition temperature of PVAc

    The early diagenetic and PETROphysical behaviour of recent cold-water CARbonate mounds in Deep Environments (PETROCARDE)

    Get PDF
    Sub-recent cold-water carbonate mounds localized in deeper slope settings on the Atlantic continental margins cannot be any longer neglected in the study of carbonate systems. They clearly play a major role in the dynamics of mixed siliciclastic-carbonate and/or carbonate-dominated continental slopes. Carbonate accumulation rates of cold-water carbonate mounds are about 4 to 12 % of the carbonate accumulation rates of tropical shallow-water reefs but exceed the carbonate accumulation rates of their slope settings by a factor of 4 to 12 (Titschack et al.,2009). These findings emphasize the importance of these carbonate factories as carbonate niches on the continental margins. The primary environmental architecture of such carbonate bodies is well-characterized. However, despite proven evidences of early diagenesis overprinting the primary environmental record (e.g. aragonite dissolution) (Foubert & Henriet, 2009), the extent of early diagenetic and biogeochemical processes shaping the petrophysical nature of mounds is until now not yet fully understood.Understanding (1) the functioning of a carbonate mound as biogeochemical reactor triggering early diagenetic processes and (2) the impact of early diagenesis on the petrophysical behaviour of a carbonate mound in space and through time are necessary (vital) for the reliable prediction of potential late diagenetic processes. Approaching the fossil carbonate mound record, through a profound study of recent carbonate bodies is innovative and will help to better understand processes observed in the fossil mound world (such as cementation, brecciation, fracturing, etc. . . ).In this study, the 155-m high Challenger mound (Porcupine Seabight, SW of Ireland), drilled during IODP Expedition 307 aboard the R/V Joides Resolution (Foubert & Henriet, 2009), and mounds from the Gulf of Cadiz (Moroccan margin) will be discussed in terms of early diagenetic processes and petrophysical behaviour. Early differential diagenesis overprints the primary environmental signals in Challenger mound, with extensive coral dissolution and the genesis of small-scaled semi-lithified layers in the Ca-rich intervals. The low cementation rates compared to the extensive dissolution patterns can be explained by an open-system diagenetic model. Moreover, Pirlet et al. (2009) emphasizes the occurrence of gypsum and dolomite in another mound system (Mound Perseverance) in Porcupine Seabight, which might be also related with fluid oxidation events in a semi-open diagenetic system. Along the Moroccan margins, fluid seepage and fluxes in pore water transport affect the development of mound structures, enhancing extensive cold-water coral dissolution and precipitation of diagenetic minerals such as dolomite, calcite, pyrite, etc. (Foubert et al., 2008). Recent carbonate mounds provide indeed an excellent opportunity to study early diagenetic processes in carbonate systems without the complications of burial and/or later meteoric diagenesis

    Spiny Snakeneck Turtles

    Get PDF
    This is where the abstract of this record would appear. This is only demonstration data

    "Belgica" Mounds in Porcupine Seabight, NE Atlantic: Biological Zonation and Environmental Control

    Get PDF
    The Belgica mounds are located on the eastern slope of Porcupine Basin between 51°10'N - 51°35'N and 11°30'W-11°45'W in water depths of 600 m to 900 m. Outcropping mounds are located on the steepest part of the slope between 750 m and 850 m. They are largest in the south and decrease in size to the north where the slope is gentler. These larger mounds merge into composite mounds up to 190 m high, 2 km to over 4 km long and have a width between 500 m - 1000 m. The eastern upslope flank of seafloor mounds is ponded with sediment while the entire western, downslope flank of the mounds remains exposed. Despite the evident asymmetry in depositional environment at both sides of a mound, Belgica mounds appear conical on seismic profiles, with an average slope of 10-15°. The base of the Belgica mounds is formed by a continuous erosional surface, probably of Miocene age. The deeply incised substratum features a very faintly stratified seismic facies and is absent in the northern part of the province. It is underlain by a sequence of sigmoidal deposits. This start-up event suggests drastic environmental changes that favoured coral growth at a certain period. Such changes may have been triggered by changes in the oceanographic circulation patterns. The mounds are associated with features related to strong currents. Zonation and biodiversity of the present coral banks was investigated by means of a videotransect and boxcoring across some of the mounds. Mainly the basinward flanks of the mounds showed patchy Lophelia communities in association with a diverse epifauna of mainly sponges and polychaetes. Along these flanks the biological communities showed a symmetrical zonation pattern. Frequently, a small patch of living Lophelia midway the mound slope grades on either side into a dead coral zone that finally turns into a coral rubble zone

    Factors Influencing Preferences and Responses Towards Drug Safety Communications:A Conjoint Experiment Among Hospital-Based Healthcare Professionals in the Netherlands

    Get PDF
    Introduction Healthcare professionals (HCPs) are informed about new drug safety issues through Direct Healthcare Professional Communications (DHPCs). The influence of DHPC content on the impact of the communication is unclear. Objectives The aim of this study was to assess the effect of content elements 'frequency of the safety issue', 'seriousness of the safety issue', 'need to take action', 'life span of drug involved' and 'type of evidence supporting the safety issue' on hospital-based HCPs' preferences and responses towards DHPCs. Methods A survey study including a conjoint experiment was performed among hospital-based HCPs in the Netherlands. Hypothetical DHPCs varying on the five content elements were constructed. Each respondent received eight out of 16 hypothetical DHPCs and was asked about (1) importance to be informed (fixed-point scale), (2) preferred communication timing (multiple options) and (3) their stated actions (multiple options). Associations were tested using generalized linear mixed models. Results In total, 178 HCPs participated. DHPCs concerning more frequent or serious safety issues, or requiring action, were associated with a higher perceived importance to be informed and a preference for immediate communication. Periodic communication was preferred for DPHCs concerning less frequent or serious safety issues. The most commonly stated action was to discuss the DHPC with colleagues. Monitoring was common when this was recommended. High frequency and seriousness were associated with more prescribing-related actions. Conclusion Frequency and seriousness of the safety issue and the recommended action are likely to influence the impact of DHPCs. The timing of communication could be tailored depending on the content, where less urgent safety issues might be communicated periodically

    Limited effect of patient and disease characteristics on compliance with hospital antimicrobial guidelines

    Get PDF
    Objective: Physicians frequently deviate from guidelines that promote prudent use of antimicrobials. We explored to what extent patient and disease characteristics were associated with compliance with guideline recommendations for three common infections. Methods: In a 1-year prospective observational study, 1,125 antimicrobial prescriptions were analysed for compliance with university hospital guidelines. Results: Compliance varied significantly between and within the groups of infections studied. Compliance was much higher for lower respiratory tract infections (LRTIs; 79%) than for sepsis (53%) and urinary tract infections (UTIs; 40%). Only predisposing illnesses and active malignancies were associated with more compliant prescribing, whereas alcohol/ intravenous drug abuse and serum creatinine levels > 130 mu mol/l were associated with less compliant prescribing. Availability of culture results had no impact on compliance with guidelines for sepsis but was associated with more compliance in UTIs and less in LRTIs. Narrowing initial broad-spectrum antimicrobial therapy to cultured pathogens was seldom practised. Most noncompliant prescribing concerned a too broad spectrum of activity when compared with guideline-recommended therapy. Conclusion: Patient characteristics had only a limited impact on compliant prescribing for a variety of reasons. Physicians seemed to practise defensive prescribing behaviour, favouring treatment success in current patients over loss of effectiveness due to resistance in future patients

    Drug Safety Issues Covered by Lay Media:A Cohort Study of Direct Healthcare Provider Communications Sent between 2001 and 2015 in The Netherlands

    Get PDF
    Background: Some drug safety issues communicated through direct healthcare professional communications (DHPCs) receive substantial media coverage, while others do not. Objectives: The objective of this study was to assess the extent of coverage of drug safety issues that have been communicated through DHPCs in newspapers and social media. A secondary aim was to explore which determinants may be associated with media coverage. Methods: Newspaper articles covering drug safety issues communicated through 387 DHPCs published between 2001 and 2015 were retrieved from LexisNexis Academic™. Social media postings were retrieved from Coosto™ for drugs included in 220 DHPCs published between 2010 and 2015. Coverage of DHPCs by newspapers and social media was assessed during the 2-month and 14-day time periods following issuance of the DHPC, respectively. Multivariate logistic regression was used to assess potential DHPC- and drug-related determinants of media coverage. Results: 41 (10.6%) DHPC safety issues were covered in newspaper articles. Newspaper coverage was associated with drugs without a specialist indication [adjusted odds ratio 5.32; 95% confidence interval (2.64–10.73)]. Negative associations were seen for time since market approval [3–5 years 0.30; (0.11–0.82), 6–11 years 0.18; (0.06–0.58)] and year of the DHPC [0.88; (0.81–0.96)]. In the social media, 180 (81.8%) drugs mentioned in 220 DHPCs were covered. Social media coverage was associated with drugs without a specialist indication [6.92; (1.56–30.64)], and for DHPCs communicating clinical safety issues [5.46; (2.03–14.66)]. Conclusions: Newspapers covered a small proportion of DHPC safety issues only. Most drugs mentioned in DHPCs were covered in social media. Coverage in both media were higher for drugs without a specialist indication
    corecore