Arsenic sorption onto disordered mackinawite as a control on the mobility of arsenic in the ambient sulphidic environment

Arsenate, As (V), sorption onto synthetic disordered mackinawite (FeSam) follows Langmuir-type behaviour. As (V) is not reduced prior to or during sorption. Arsenite, As (III) sorption can be expressed by a Freundlich isotherm. Comparison of the experimental sorption isotherms to field data describing the mobility of arsenic in a Bangladesh aquifer shows that arsenic mobility may be controlled by As (V) sorption onto FeSam in the aquifer sediment

Arsenic mobility in the ambient sulfidic environment: Sorption of arsenic(V) and arsenic(III) onto disordered mackinawite

Arsenate, As(V), sorption onto synthetic iron(II) monosulfide, disordered mackinawite (FeS), is fast. As(V) sorption decreases above the point of zero surface charge of FeS and follows the pH-dependent concentration of positively charged surface species. No redox reaction is observed between the As(V) ions and the mineral surface over the time span of the experiments. This observation shows that As(V) dominantly forms an outer-sphere complex at the surface of mackinawite. Arsenite, As(III), sorption is not strongly pH-dependent and can be expressed by a Freundlich isotherm. Sorption is fast, although slower than that of As(V). As(III) also forms an outer-sphere complex at the surface of mackinawite. In agreement with previous spectroscopic studies, complexation at low As(V) and As(III) concentration occurs preferentially at the mono-coordinated sulfide edge sites. The Kd (L g−1) values obtained from linear fits to the isotherm data are ∼9 for As(V) and ∼2 for As(III). Stronger sorption of As(V) than As(III), and thus a higher As(III) mobility, may be reflected in natural anoxic sulfidic waters when disordered mackinawite controls arsenic mobility

Why do patients want to have their blood tested? A qualitative study of patient expectations in general practice

BACKGROUND: General practitioners often take their impression of patients' expectations into account in their decision to have blood tests done. It is commonly recommended to involve patients in decision-making during consultations. The study aimed to obtain detailed information on patients' expectations about blood tests. METHODS: Qualitative study among patients in waiting rooms of general practices. Each patient was presented with a short questionnaire about their preferences in terms of diagnostics. Patients who would like blood tests to be done were interviewed. RESULTS: Fifty-seven (26%) of the 224 respondents wanted blood tests. Twenty-two were interviewed. Patients overestimated the qualities of blood tests. Favourable test results were regarded as proof of good health. Patients regarded blood tests as a useful instrument to screen for serious disorders, and were confirmed in this belief by people in their social environment and by the media. Many patients expected their GP to take an active test ordering approach, though some indicated that they might be convinced if their GP proposed a wait-and-see policy. CONCLUSIONS: GPs' perceptions about patient expectations seem justified: patients appear to have high hopes for testing as a diagnostic tool. They expect diagnostic certainty without mistakes and a proof of good health. The question is whether it would be desirable to remove patients' misconceptions, allowing them to participate in policy decisions on the basis of sound information, or whether it would be better to leave the misconceptions uncontested, in order to retain the 'magic' of additional tests and reassure patients. We expect that clarifying the precise nature of patients' expectations by the GP may be helpful in creating a diagnostic strategy that satisfies both patients and GPs. GPs will have to balance the benefits of reassuring their patients by means of blood tests which may be unnecessary against the benefits of avoiding unnecessary tests. Further research is needed into the effects of different types of patient information and the effects of testing on satisfaction and anxiety

Arduous implementation: Does the Normalisation Process Model explain why it's so difficult to embed decision support technologies for patients in routine clinical practice

Background: decision support technologies (DSTs, also known as decision aids) help patients and professionals take part in collaborative decision-making processes. Trials have shown favorable impacts on patient knowledge, satisfaction, decisional conflict and confidence. However, they have not become routinely embedded in health care settings. Few studies have approached this issue using a theoretical framework. We explained problems of implementing DSTs using the Normalization Process Model, a conceptual model that focuses attention on how complex interventions become routinely embedded in practice.Methods: the Normalization Process Model was used as the basis of conceptual analysis of the outcomes of previous primary research and reviews. Using a virtual working environment we applied the model and its main concepts to examine: the 'workability' of DSTs in professional-patient interactions; how DSTs affect knowledge relations between their users; how DSTs impact on users' skills and performance; and the impact of DSTs on the allocation of organizational resources.Results: conceptual analysis using the Normalization Process Model provided insight on implementation problems for DSTs in routine settings. Current research focuses mainly on the interactional workability of these technologies, but factors related to divisions of labor and health care, and the organizational contexts in which DSTs are used, are poorly described and understood.Conclusion: the model successfully provided a framework for helping to identify factors that promote and inhibit the implementation of DSTs in healthcare and gave us insights into factors influencing the introduction of new technologies into contexts where negotiations are characterized by asymmetries of power and knowledge. Future research and development on the deployment of DSTs needs to take a more holistic approach and give emphasis to the structural conditions and social norms in which these technologies are enacte

Oral biofilm models for mechanical plaque removal

In vitro plaque removal studies require biofilm models that resemble in vivo dental plaque. Here, we compare contact and non-contact removal of single and dual-species biofilms as well as of biofilms grown from human whole saliva in vitro using different biofilm models. Bacteria were adhered to a salivary pellicle for 2 h or grown after adhesion for 16 h, after which, their removal was evaluated. In a contact mode, no differences were observed between the manual, rotating, or sonic brushing; and removal was on average 39%, 84%, and 95% for Streptococcus mutans, Streptococcus oralis, and Actinomyces naeslundii, respectively, and 90% and 54% for the dual- and multi-species biofilms, respectively. However, in a non-contact mode, rotating and sonic brushes still removed considerable numbers of bacteria (24–40%), while the manual brush as a control (5–11%) did not. Single A. naeslundii and dual-species (A. naeslundii and S. oralis) biofilms were more difficult to remove after 16 h growth than after 2 h adhesion (on average, 62% and 93% for 16- and 2-h-old biofilms, respectively), while in contrast, biofilms grown from whole saliva were easier to remove (97% after 16 h and 54% after 2 h of growth). Considering the strong adhesion of dual-species biofilms and their easier more reproducible growth compared with biofilms grown from whole saliva, dual-species biofilms of A. naeslundii and S. oralis are suggested to be preferred for use in mechanical plaque removal studies in vitro

Efficacy of essential oil mouthwash with and without alcohol: a 3-Day plaque accumulation model

<p>Abstract</p> <p>Background</p> <p>The aim of this study was to evaluate the antiplaque effect of a new alcohol free essential oil mouthwash with respect to a control of an essential oil with alcohol mouthwash, using an <it>in vivo </it>plaque regrowth model of 3-days.</p> <p>Methods</p> <p>The study was designed as a double-masked, randomized, crossover clinical trial, involving 30 volunteers to compare two different essential oil containing mouthwashes, during a 3-day plaque accumulation model. After receiving a thorough professional prophylaxis at the baseline, over the next 3-days each volunteer refrained from all oral hygiene measures and had two daily rinses with 20 ml of the test mouthwash (alcohol free essential oil) or the control mouthwash (essential oil with alcohol). At the end of the each experimental period, plaque was assessed and the panelists filled out a questionnaire. Each subject underwent a 14 days washout period and there was a second allocation.</p> <p>Results</p> <p>The essential oil mouthwash with ethanol shows a better inhibitory effect of plaque regrowth in 3-days than the mouthwash test with only essential oil in the whole mouth (plaque index = 2.18 against 2.46, respectively, p < 0.05); for the lower jaw (plaque index = 2.28 against 2.57, respectively, p < 0.05); for the upper jaw (plaque index = 2.08 against 2.35, respectively, p < 0.05); for the incisors (plaque index = 1.93 against 2.27, respectively, p < 0.05); and the canines (plaque index = 1.99 against 2.47, respectively, p < 0.05).</p> <p>Conclusion</p> <p>The essential oil containing mouthwash without alcohol seems to have a less inhibiting effect on the plaque regrowth than the traditional alcoholic solution.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov <a href="http://www.clinicaltrials.gov/ct2/show/NCT01411618">NCT01411618</a></p

Assessment of Medical Students’ Shared Decision-Making in Standardized Patient Encounters

BackgroundShared decision-making, in which physicians and patients openly explore beliefs, exchange information, and reach explicit closure, may represent optimal physician-patient communication. There are currently no universally accepted methods to assess medical students' competence in shared decision-making.ObjectiveTo characterize medical students' shared decision-making with standardized patients (SPs) and determine if students' use of shared decision-making correlates with SP ratings of their communication.DesignRetrospective study of medical students' performance with four SPs.ParticipantsSixty fourth-year medical students.MeasurementsObjective blinded coding of shared decision-making quantified as decision moments (exploration/articulation of perspective, information sharing, explicit closure for a particular decision); SP scoring of communication skills using a validated checklist.ResultsOf 779 decision moments generated in 240 encounters, 312 (40%) met criteria for shared decision-making. All students engaged in shared decision-making in at least two of the four cases, although in two cases 5% and 12% of students engaged in no shared decision-making. The most commonly discussed decision moment topics were medications (n = 98, 31%), follow-up visits (71, 23%), and diagnostic testing (44, 14%). Correlations between the number of decision moments in a case and students' communication scores were low (rho = 0.07 to 0.37).ConclusionsAlthough all students engaged in some shared decision-making, particularly regarding medical interventions, there was no correlation between shared decision-making and overall communication competence rated by the SPs. These findings suggest that SP ratings of students' communication skill cannot be used to infer students' use of shared decision-making. Tools to determine students' skill in shared decision-making are needed

A cluster randomized controlled trial aimed at implementation of local quality improvement collaboratives to improve prescribing and test ordering performance of general practitioners: Study Protocol

<p>Abstract</p> <p>Background</p> <p>The use of guidelines in general practice is not optimal. Although evidence-based methods to improve guideline adherence are available, variation in physician adherence to general practice guidelines remains relatively high. The objective for this study is to transfer a quality improvement strategy based on audit, feedback, educational materials, and peer group discussion moderated by local opinion leaders to the field. The research questions are: is the multifaceted strategy implemented on a large scale as planned?; what is the effect on general practitioners' (GPs) test ordering and prescribing behaviour?; and what are the costs of implementing the strategy?</p> <p>Methods</p> <p>In order to evaluate the effects, costs and feasibility of this new strategy we plan a multi-centre cluster randomized controlled trial (RCT) with a balanced incomplete block design. Local GP groups in the south of the Netherlands already taking part in pharmacotherapeutic audit meeting groups, will be recruited by regional health officers. Approximately 50 groups of GPs will be randomly allocated to two arms. These GPs will be offered two different balanced sets of clinical topics. Each GP within a group will receive comparative feedback on test ordering and prescribing performance. The feedback will be discussed in the group and working agreements will be created after discussion of the guidelines and barriers to change. The data for the feedback will be collected from existing and newly formed databases, both at baseline and after one year.</p> <p>Discussion</p> <p>We are not aware of published studies on successes and failures of attempts to transfer to the stakeholders in the field a multifaceted strategy aimed at GPs' test ordering and prescribing behaviour. This pragmatic study will focus on compatibility with existing infrastructure, while permitting a certain degree of adaptation to local needs and routines.</p> <p>Trial registration</p> <p>Nederlands Trial Register ISRCTN40008171</p

Ice loss from the East Antarctic Ice Sheet during late Pleistocene interglacials

Understanding ice sheet behaviour in the geological past is essential for evaluating the role of the cryosphere in the climate system and for projecting rates and magnitudes of sea level rise in future warming scenarios1,2,3,4. Although both geological data5,6,7 and ice sheet models3,8 indicate that marine-based sectors of the East Antarctic Ice Sheet were unstable during Pliocene warm intervals, the ice sheet dynamics during late Pleistocene interglacial intervals are highly uncertain3,9,10. Here we provide evidence from marine sedimentological and geochemical records for ice margin retreat or thinning in the vicinity of the Wilkes Subglacial Basin of East Antarctica during warm late Pleistocene interglacial intervals. The most extreme changes in sediment provenance, recording changes in the locus of glacial erosion, occurred during marine isotope stages 5, 9, and 11, when Antarctic air temperatures11 were at least two degrees Celsius warmer than pre-industrial temperatures for 2,500 years or more. Hence, our study indicates a close link between extended Antarctic warmth and ice loss from the Wilkes Subglacial Basin, providing ice-proximal data to support a contribution to sea level from a reduced East Antarctic Ice Sheet during warm interglacial intervals. While the behaviour of other regions of the East Antarctic Ice Sheet remains to be assessed, it appears that modest future warming may be sufficient to cause ice loss from the Wilkes Subglacial Basin

De rol van bodemkwaliteit in ruimtelijke ordening

Changes in land use in the Netherlands are anticipated on a large scale. Soil quality, however, hardly plays a role in spatial planning, which was reason enough to analyse the relationship between land use and soil quality on a national scale using ecological data. Despite major changes in land use, the strong linkage between land use and soil type was seen to continue. Soil management practices, historical land use and the geographical situation influence the relationship between land use and soil properties; the influence of land use on several soil properties is also discernable. Thus soil biodiversity can be said to be influenced by farming intensity. Land use is not always situated in areas where benefits in terms of yield are high. Less than 20% of the arable farming and pasture is situated on unsuitable soil, whereas over 40% of the forests grow on unsuitable soil. Region-specific environmental policy offers many possibilities for differentiation according to land use. It is also possible to match occurring soil quality to both existing and desired land use.Veranderingen in bodemgebruik zijn op grote schaal voorzien in Nederland. De kwaliteit van de bodem speelt echter nauwelijks een rol in de ruimtelijke ordening. Wij analyseerden de relatie tussen bodemgebruik en bodemkwaliteit, met gebruik van ecologische data en op nationaal schaalniveau. Ondanks grootschalige veranderingen in bodemgebruik, is er nog steeds een verband tussen bodemtype en bodemgebruik. Bodembeheer, historisch bodemgebruik en de geografische situering beinvloeden deze relatie, maar ook de invloed van bodemgebruik op verschillende bodemeigenschappen is herkenbaar. Zo wordt bodembiodiversiteit beinvloed door de intensiteit van bodemgebruik door de landbouw. Bodemgebruik is niet altijd daar gesitueerd waar de voordelen in termen van opbrengst hoog zijn. Minder dan 20% van de akkerbouw en veeteelt is gesitueerd op ongeschikte bodem, terwijl dat geldt voor meer dan 40% van de bosbouw. Gebiedsgericht milieubeleid biedt veel mogelijkheden om te differentieren naar bodemgebruik, waardoor het mogelijk wordt het bodemgebruik af te stemmen op de (gewenste) bodemkwaliteit