113 research outputs found

    Quantitative imaging of concentrated suspensions under flow

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    We review recent advances in imaging the flow of concentrated suspensions, focussing on the use of confocal microscopy to obtain time-resolved information on the single-particle level in these systems. After motivating the need for quantitative (confocal) imaging in suspension rheology, we briefly describe the particles, sample environments, microscopy tools and analysis algorithms needed to perform this kind of experiments. The second part of the review focusses on microscopic aspects of the flow of concentrated model hard-sphere-like suspensions, and the relation to non-linear rheological phenomena such as yielding, shear localization, wall slip and shear-induced ordering. Both Brownian and non-Brownian systems will be described. We show how quantitative imaging can improve our understanding of the connection between microscopic dynamics and bulk flow.Comment: Review on imaging hard-sphere suspensions, incl summary of methodology. Submitted for special volume 'High Solid Dispersions' ed. M. Cloitre, Vol. xx of 'Advances and Polymer Science' (Springer, Berlin, 2009); 22 pages, 16 fig

    RoB 2: a revised tool for assessing risk of bias in randomised trials

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    Assessment of risk of bias is regarded as an essential component of a systematic review on the effects of an intervention. The most commonly used tool for randomised trials is the Cochrane risk-of-bias tool. We updated the tool to respond to developments in understanding how bias arises in randomised trials, and to address user feedback on and limitations of the original tool

    Disturbance and diversity at two spatial scales

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    The spatial scale of disturbance is a factor potentially influencing the relationship between disturbance and diversity. There has been discussion on whether disturbances that affect local communities and create a mosaic of patches in different successional stages have the same effect on diversity as regional disturbances that affect the whole landscape. In a microcosm experiment with metacommunities of aquatic protists, we compared the effect of local and regional disturbances on the disturbance–diversity relationship. Local disturbances destroyed entire local communities of the metacommunity and required reimmigration from neighboring communities, while regional disturbances affected the whole metacommunity but left part of each local community intact. Both disturbance types led to a negative relationship between disturbance intensity and Shannon diversity. With strong local disturbance, this decrease in diversity was due to species loss, while strong regional disturbance had no effect on species richness but reduced the evenness of the community. Growth rate appeared to be the most important trait for survival after strong local disturbance and dominance after strong regional disturbance. The pattern of the disturbance–diversity relationship was similar for both local and regional diversity. Although local disturbances at least temporally increased beta diversity by creating a mosaic of differently disturbed patches, this high dissimilarity did not result in regional diversity being increased relative to local diversity. The disturbance–diversity relationship was negative for both scales of diversity. The flat competitive hierarchy and absence of a trade-off between competition and colonization ability are a likely explanation for this pattern

    Warfarin therapy and incidence of cerebrovascular complications in left-sided native valve endocarditis

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    International audienceAnticoagulant therapy has been anticipated to increase the risk of cerebrovascular complications (CVC) in native valve endocarditis (NVE). This study investigates the relationship between ongoing oral anticoagulant therapy and the incidence of symptomatic CVC in left-sided NVE. In a prospective cohort study, the CVC incidence was compared between NVE patients with and without ongoing warfarin. Among 587 NVE episodes, 48 (8%) occurred in patients on warfarin. A symptomatic CVC was seen in 144 (25%) patients, with only three on warfarin. CVC were significantly less frequent in patients on warfarin (6% vs. 26%, odds ratio [OR] 0.20, 95% confidence interval [CI] 0.06-0.6,  = 0.006). No increase in haemorrhagic lesions was detected in patients on warfarin. aetiology (adjusted OR [aOR] 6.3, 95% CI 3.8-10.4) and vegetation length (aOR 1.04, 96% CI 1.01-1.07) were risk factors for CVC, while warfarin on admission (aOR 0.26, 95% CI 0.07-0.94), history of congestive heart failure (adjusted OR 0.22, 95% CI 0.1-0.52) and previous endocarditis (aOR 0.1, 95% CI 0.01-0.79) correlated with lower CVC frequency

    Time-aging time-stress superposition in soft glass under tensile deformation field

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    We have studied the tensile deformation behaviour of thin films of aging aqueous suspension of Laponite, a model soft glassy material, when subjected to a creep flow field generated by a constant engineering normal stress. Aqueous suspension of Laponite demonstrates aging behaviour wherein it undergoes time dependent enhancement of its elastic modulus as well as its characteristic relaxation time. However, under application of the normal stress, the rate of aging decreases and in the limit of high stress, the aging stops with the suspension now undergoing a plastic deformation. Overall, it is observed that the aging that occurs over short creep times at small normal stresses is same as the aging that occurs over long creep times at large normal stresses. This observation allows us to suggest an aging time - process time - normal stress superposition principle, which can predict rheological behaviour at longer times by carrying out short time tests.Comment: 26 pages, 7 figures, To appear in Rheologica Act

    Review of Community Pharmacy Staff Educational Needs for Supporting Mental Health Consumers and Carers

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    Development of a mental health education package for community pharmacy staff should be informed by mental health consumers/carers’ needs, expectations and experiences, and staff knowledge, skills and attitudes. This review (1) explored research on community pharmacy practice and service provision for mental health consumers/carers, and (2) identified validated methods for assessing staff knowledge, skills and attitudes about mental illness to inform the development of a training questionnaire. A literature scan using key words knowledge, skills, attitudes, and beliefs combined with community pharmacy, pharmacist, and pharmacy support staff, and mental illness, depression, anxiety was conducted. A small number of studies were found that used reliable methods to assess pharmacists’ training needs regarding mental illness and treatment options. There was little published specifically in relation to depression and anxiety in community pharmacy practice. No studies assessed the training needs of pharmacy support staff. A systematic analysis of pharmacy staff learning needs is warranted

    Nutritional indices in the gypsy moth ( Lymantria dispar (L.)) under field conditions and host switching situations

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    A large proportion of gypsy moths ( Lymantria dispar (L.)) are likely to experience multiple species diets in the field due to natural wandering and host switching which occurs with these insects. Nutritional indices in fourth and fifth instar gypsy moth larvae were studied in the field for insects that were switched to a second host species when they were fourth instars. The tree species used as hosts were northern pin oak ( Quercus ellipsoidalis E. J. Hill), white oak ( Q. alba L.), big-tooth aspen ( Populus grandidentata Michx.), and trembling aspen ( P. tremuloides Michx.). Conclusions of this study include: 1) Insects which fed before the host switch on northern pin oak performed better after the host switch than did insects with other types of early dietary experience. While the northern pin oak-started insects had very low relative food consumption rates on their second host species immediately after the switch, one instar later they had the highest ranked consumption rates. During both instars they had the second highest efficiencies of converting ingested and digested food to body mass. High food consumption rates and relatively high efficiency of food conversion helped these insects to obtain the highest ranked mean relative growth rates in the fifth instar compared to the relative growth rates obtained by insects from any of the other first host species. 2) Among the four host species examined, a second host of trembling aspen was most advantageous for the insects. Feeding on this species after the switch led to higher larval weights and higher relative growth rates for insects than did any of the other second host species. The insects on trembling aspen attained excellent growth despite only mediocre to low food conversion efficiencies. The low efficiencies were offset by high relative food consumption rates. 3) Low food consumption rates often tend to be paired with high efficiency of conversion and vice versa. 4) There is no discernable tendency for the first plant species eaten to cause long-term inductions which affect the ability of gypsy moths to utilize subsequent host plants. Insects did not tend to consume more, grow faster, or be more efficient if their second host plant was either the same as their rearing plant or congeneric to it. Methods are delineated which allow values of nutritional indices to be obtained for insects on intact host plants under field conditions. These methods are useful for the purpose of answering questions about the relative effects that different diet treatments have on insect response.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47803/1/442_2004_Article_BF00323145.pd

    Biochemical components of wild relatives of chickpea confer resistance to pod borer, Helicoverpa armigera

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    Efforts are being made to develop chickpea varieties with resistance to the pod borer, Helicoverpa armigera for reducing pesticide use and minimizing the extent of losses due to this pest. However, only low to moderate levels of resistance have been observed in the cultivated chickpea to this polyphagous pest. Hence, it is important to explore wild relatives as resistance sources to develop insect-resistant cultivars. Therefore, we studied different biochemical components that confer resistance to H. armigera in a diverse array of wild relatives of chickpea. Accessions belonging to wild relatives of chickpea exhibited high levels of resistance to H. armigera as compared to cultivated chickpea genotypes in terms of lower larval survival, pupation and adult emergence, decreased larval and pupal weights, prolonged larval and pupal developmental periods and reduced fecundity of the H. armigera when reared on artificial diet impregnated with lyophilized leaf powders. Amounts of proteins and phenols in different accessions of chickpea wild relatives were significantly and negatively correlated with larval weight, pupation and adult emergence. Phenols showed a negative correlation with pupal weight and fecundity, but positive correlation with pupal period. Total soluble sugars showed a negative correlation with larval period, but positive correlation with pupation and pupal weight, while tannins showed a positive correlation with larval weight, pupation and adult emergence. The flavonoid compounds such as chlorogenic acid, ferulic acid, naringin, 3,4-dihydroxy flavones, quercetin, naringenin, genistein, biochanin-A and formononetin that were identified through HPLC fingerprints, exhibited negative effects on survival and development of H. armigera reared on artificial diet impregnated with lyophilized leaf powders. The wild relatives with diverse mechanisms of resistance conferred by different biochemical components can be used as sources of resistance in chickpea breeding programs to develop cultivars with durable resistance to H. armigera for sustainable crop production
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