721 research outputs found

    Long-Term Trends in Calcifying Plankton and pH in the North Sea

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    Relationships between six calcifying plankton groups and pH are explored in a highly biologically productive and data-rich area of the central North Sea using time-series datasets. The long-term trends show that abundances of foraminiferans, coccolithophores, and echinoderm larvae have risen over the last few decades while the abundances of bivalves and pteropods have declined. Despite good coverage of pH data for the study area there is uncertainty over the quality of this historical dataset; pH appears to have been declining since the mid 1990s but there was no statistical connection between the abundance of the calcifying plankton and the pH trends. If there are any effects of pH on calcifying plankton in the North Sea they appear to be masked by the combined effects of other climatic (e.g. temperature), chemical (nutrient concentrations) and biotic (predation) drivers. Certain calcified plankton have proliferated in the central North Sea, and are tolerant of changes in pH that have occurred since the 1950s but bivalve larvae and pteropods have declined. An improved monitoring programme is required as ocean acidification may be occurring at a rate that will exceed the environmental niches of numerous planktonic taxa, testing their capacities for acclimation and genetic adaptation

    One-Point Probability Distribution Functions of Supersonic Turbulent Flows in Self-Gravitating Media

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    Turbulence is essential for understanding the structure and dynamics of molecular clouds and star-forming regions. There is a need for adequate tools to describe and characterize the properties of turbulent flows. One-point probability distribution functions (pdf's) of dynamical variables have been suggested as appropriate statistical measures and applied to several observed molecular clouds. However, the interpretation of these data requires comparison with numerical simulations. To address this issue, SPH simulations of driven and decaying, supersonic, turbulent flows with and without self-gravity are presented. In addition, random Gaussian velocity fields are analyzed to estimate the influence of variance effects. To characterize the flow properties, the pdf's of the density, of the line-of-sight velocity centroids, and of the line centroid increments are studied. This is supplemented by a discussion of the dispersion and the kurtosis of the increment pdf's, as well as the spatial distribution of velocity increments for small spatial lags. From the comparison between different models of interstellar turbulence, it follows that the inclusion of self-gravity leads to better agreement with the observed pdf's in molecular clouds. The increment pdf's for small spatial lags become exponential for all considered velocities. However, all the processes considered here lead to non-Gaussian signatures, differences are only gradual, and the analyzed pdf's are in addition projection dependent. It appears therefore very difficult to distinguish between different physical processes on the basis of pdf's only, which limits their applicability for adequately characterizing interstellar turbulence.Comment: 38 pages (incl. 17 figures), accepted for publication in ApJ, also available with full resolution figures at http://www.strw.leidenuniv.nl/~klessen/Preprint

    A phase I clinical and pharmacological study evaluating vinflunine in combination with doxorubicin as first line treatment in metastatic breast cancer

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    Vinfunine (VFL) is a novel bifluorinated tubulin-targeted agent of the vinca alkaloids class active in advanced stage breast cancer. We conducted a phase I study combining VFL with doxorubicin (DXR) to define the recommended dose (RD), safety, pharmacokinetic (PK) interaction and efficacy. Two schedules (day 1 every 3weeks; days 1 and 8 every 3weeks) were investigated as first line chemotherapy in metastatic breast cancer patients. Thirty-two patients received a total of 162 cycles of the VFL-DXR combination (median 6). The RDs were VFL 250mg/m2/DXR 40mg/m2 every 3weeks for schedule 1 and VFL 120mg/m2/DXR 25mg/m2 days 1 and 8 every 3weeks for schedule 2. The main dose-limiting toxicity was neutropenia. The most frequent non-hematological adverse events were nausea, fatigue, constipation, vomiting, anorexia, stomatitis and dyspnea. Objective response rate was reached in 47.1% of the patients. No PK interaction was observed. VFL-DXR combination is feasible with manageable toxicity. The antitumor activity was promising and supports further evaluatio

    Pigmented villonodular synovitis of the midfoot

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    A 60-year-old man presented with a longstanding slowly growing swelling at the dorsal aspect of the left midfoot. The lesion was imaged with CT, ultrasound, and MR. On CT bony erosions were evident. On MR the lesions appeared bifocal and one component was hypointense on T2 weighted images suggesting hemosiderin deposits. The other component was hyperintense on T2 which is more unusual for PVNS. Imaging findings, however, suggested PVNS which was pathologically confirmed. A unique finding in this case is the late age of presentation of the disorder. Also the bifocal nature of the lesion is relatively uncommon

    Vistuig met ballen: Vergelijkend onderzoek vangstsamenstelling aangepast twinrigtuig

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    De Ekofish Groep BV werkt aan een tuiginnovatie voor hun twinrigtuig waarmee de bodemberoering, de hoeveelheid discards en het brandstofverbruik zou moeten afnemen. Het nieuwe vistuig heeft zwevende borden in plaats van demersale borden, ballen op de sweeps waardoor deze minder over de bodem slepen en Dyneema viskabels in plaats van de conventionele, zwaardere, kabels. Het nieuwe tuig wordt ‘vistuig met ballen’ genoemd. IMARES is betrokken bij het vergelijken van de vangsten van het aangepaste met het conventionele vistuig. Door een vangstvergelijking tussen de twee tuigen is onderzocht of de hoeveelheid discards afnemen als gevolg van deze tuiginnovatie. Waarnemers van IMARES hebben meegevaren aan boord van twee schepen van de Ekofish Groep BV: de PD43, die viste met het aangepaste twinrigtuig en de PD147 die viste met een conventioneel twinrigtuig. De vergelijking van de vangstsamenstelling tussen beide tuigen laat zien dat met het nieuwe tuig significant minder bodemdieren (44%, in totale aantallen) worden gevangen. Er zijn geen significante verschillen aangetoond in de hoeveelheid (kg) gediscarde vis

    Vaccination with Fendrix of prior nonresponding patients with HIV has a high success rate

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    Background: Patients with HIV have a poor serological conversion rate with the standard vaccination strategy against hepatitis B virus (HBV) of around 50%. Vaccination with Fendrix confers much better results in these patients. In this study, we tested the effect of revaccination with Fendrix in prior nonresponding patients with HIV and aimed to determine which factors are associated with seroconversion. Methods: Eight Dutch HIV treatment centers participated in this retrospective study. Patients infected with HIV-1 and nonresponding to prior course of vaccination against HBV (anti-HBs <10 IU/ml) and who had Fendrix as a second, third or fourth effort to achieve seroconversion were eligible for inclusion. Primary outcome was the proportion of patients with seroconversion after revaccination with Fendrix. Univariate binary logistic regression analyses were used to determine which factors could be used as predictors for seroconversions. Results: We included 100 patients with HIV. The mean age was 47.3 (11.0) years and 86% were men. Revaccination with Fendrix showed a seroconversion rate of 81% (95% confidence interval 72–88%). Median nadir CD4þ cell count was 300 (20–1040) cells/ ml and median CD4þ cell count at the time at starting vaccination with Fendrix was 605 (210–1190) cells/ml. Regression analyses showed no significant factor associated with seroconversion. Conclusions: Revaccination with Fendrix of patients prior nonresponding to other hepatitis B vaccination strategies has a high success rate. Eighty-one percentage responded with seroconversion, irrespective of CD4þ cell count
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