220 research outputs found
Review of the Netherlands’ contribution to the humanitarian response to the Syria Crisis: 2011-2014
This report examines the Netherlands contribution to the humanitarian response to the Syrian crisis and the impact on neighbouring countries in the period 15 March 2011 to 31 December 2014. Data and other types of information used for the analysis are actual until 31 December
Ricci flows with unbounded curvature
We show that any noncompact Riemann surface admits a complete Ricci flow
g(t), t\in[0,\infty), which has unbounded curvature for all t\in[0,\infty).Comment: 12 pages, 1 figure; updated reference
Reconstruction and growth of the early tree Calamophyton (Pseudosporochnales, Cladoxylopsida) based on exceptionally complete specimens from Lindlar, Germany (Mid-Devonian): organic connection of Calamophyton branches and Duisbergia trunks
Middle Devonian Pseudosporochnales (Cladoxylopsida) are among the earliest tree-sized plants in the fossil record. We describe here new and spectacular complete specimens of Calamophyton primaevum Kräusel et Weyland from Lindlar (Eifelian, early Mid-Devonian), Germany. These demonstrate for the first time roots, trunk bases, trunks, trunk apices, and crowns of attached digitate branches in organic connection for multiple specimens of one taxon of pseudosporochnaleans from the same horizon. Completely preserved trunks are between 0.8 and 2.0 m long. Middle portions of the trunks demonstrate that the branches were abscised a short distance from the trunk surface, leaving branch bases of consistent length superficially similar to leaves. Such trunks and “leaves” were previously named Duisbergia mirabilis Kräusel et Weyland. Trunk diameter decreases distally in the lower half of the trunk but usually increases distally below the top. Some trunks may have divided dichotomously. The trunk apex is domed and takes up the entire width of the top of the trunk, up to 100 mm in diameter. Overall, the new evidence is not consistent with existing models of pseudosporochnalean growth. The suite of specimens suggests that the upward-growing primary body of the trunk increased in diameter, reaching a mature diameter ∼1–2 m from the ground. Lower parts of the plant are therefore likely to have increased in diameter by a process of secondary growth
Existence of Ricci flows of incomplete surfaces
We prove a general existence result for instantaneously complete Ricci flows
starting at an arbitrary Riemannian surface which may be incomplete and may
have unbounded curvature. We give an explicit formula for the maximal existence
time, and describe the asymptotic behaviour in most cases.Comment: 20 pages; updated to reflect galley proof correction
Monitoring of unbound protein in vesicle suspensions with off-null ellipsometry
In studies on the binding of proteins to small unilamellar phospholipid vesicles (SUV), the concentration of unbound protein usually remains unknown, because the vesicles cannot be separated from the bulk solution. In the present study, this limitation was overcome by addition of a supported planar phospholipid bilayer to the cuvette containing a vesicle suspension. Ellipsometric measurement of the protein adsorption velocities on this bilayer allowed determination of the concentrations of unbound protein. At high protein concentrations the adsorption is rapidly completed and the usual null-ellipsometry is too slow to obtain well-defined initial adsorption rates. Therefore, an off-null technique was developed, allowing measurement of the adsorbed protein mass at time intervals of 20 ms. Binding of prothrombin and coagulation factor Xa was measured in SUV suspensions prepared from a 20Va dioleoylphosphatidylserine (DOPS) and 80Vo dioleoylphosphatidylcholine (DOPC) phospho-lipid mixture. For prothrombin, a dissociation constant Kd:140+27 nM (mean*S.E.) and maximal surface concentration fL".: (8.9 + 0.8) ' 10- 3 mole of protein per mole of lipid, were obtained. For factor Xa, these values were K d: 49.6 + 6.3 nM and 1-u *:Q3.0 t 1.4) ' 10-3 mole of protein per mole of lipid. These binding parameters are similar to those obtained earlier for planar bilayers. Apparently, the binding of factor Xa and prothrombin is not dependent on surface curvature. r2
Testing the Effects of Automated Navigation in a General Population Web Survey
This study investigates how an auto-forward design, where respondents navigate through a web survey automatically, affects response times and navigation behavior in a long mixed-device web survey. We embedded an experiment in a health survey administered to the general population in The Netherlands to test the auto-forward design against a manual-forward design. Analyses are based on detailed paradata that keep track of the respondents’ behavior in navigating the survey. We find that an auto-forward design decreases completion times and that questions on pages with automated navigation are answered significantly faster compared to questions on pages with manual navigation. However, we also find that respondents use the navigation buttons more in the auto-forward condition compared to the manual-forward condition, largely canceling out the reduction in survey duration. Furthermore, we also find that the answer options 'I don't know' and 'I rather not say' are used just as often in the auto-forward condition as in the manual-forward condition, indicating no differences in satisficing behavior. We conclude that auto-forwarding can be used to reduce completing times, but we also advice to carefully consider mixing manual and auto-forwarding within a survey
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