Development and application of a sensitive, high precision weighing lysimeter for use in greenhouses

A high precision weighing lysimeter for measuring evapotranspiration in greenhouses was developed. The instrument has a measurement of sensitivity of one part in 106, that is one order of magnitude better than any other so far described in the literature. With it, evaporation rates in a greenhouse, even at night, can be measured on a one minute time scale. Development and construction of the instrument are described and measurements of the transpiration of a tomato crop in a greenhouse are used to demonstrate its capabilities

Strain-induced kinetics of intergrain defects as the mechanism of slow dynamics in the nonlinear resonant response of humid sandstone bars

A closed-form description is proposed to explain nonlinear and slow dynamics effects exhibited by sandstone bars in longitudinal resonance experiments. Along with the fast subsystem of longitudinal nonlinear displacements we examine the strain-dependent slow subsystem of broken intergrain and interlamina cohesive bonds. We show that even the simplest but phenomenologically correct modelling of their mutual feedback elucidates the main experimental findings typical for forced longitudinal oscillations of sandstone bars, namely, (i) hysteretic behavior of a resonance curve on both its up- and down-slopes, (ii) linear softening of resonant frequency with increase of driving level, and (iii) gradual recovery (increase) of resonant frequency at low dynamical strains after the sample was conditioned by high strains. In order to reproduce the highly nonlinear elastic features of sandstone grained structure a realistic non-perturbative form of strain potential energy was adopted. In our theory slow dynamics associated with the experimentally observed memory of peak strain history is attributed to strain-induced kinetic changes in concentration of ruptured inter-grain and inter-lamina cohesive bonds causing a net hysteretic effect on the elastic Young's modulus. Finally, we explain how enhancement of hysteretic phenomena originates from an increase in equilibrium concentration of ruptured cohesive bonds that are due to water saturation.Comment: 5 pages, 3 figure

Ons Europaplein : ontwerp voor een nieuw Europaplein in Renkum

Het Europaplein in Renkum ligt er triest bij. Er is veel achterstallig onderhoud en het plein wordt als veel te stenig ervaren. Op basis van een gedegen sociaal ruimtelijke analyse en in nauwe samenspraak met de gebruikers van het plein is een schetsontwerp gemaakt voor een nieuw Europaplein: interessant voor iedereen met fijne plekken om te zitten en te spelen met midden op het plein mogelijkheden voor verschillende activiteiten. Het ontwerp is zo opgebouwd dat een gefaseerde realisatie mogelijk is. Afhankelijk van beschikbare financiering kunnen verschillende opties al dan niet worden uitgevoerd. Het ontwerp hoeft niet in één keer uitgevoerd te worden. De aanleg kan gespreid gerealiseerd worden zonder dat de kwaliteit van de uiteindelijke beoogde verbeteringen in het geding komt

Release of Soluble Receptors for Tumor Necrosis Factor in Clinical Sepsis and Experimental Endotoxemia

To assess the role of tumor necrosis factor (TNF) in the appearance of soluble TNF receptors (sTNFRs), 20 consecutive patients with a clinical diagnosis of sepsis were studied as were 7 chimpanzees after administration of endotoxin (4 ng/kg) with or without pentoxifylline. The patients had markedly elevated serum levels of sTNFR-p55 and sTNFR-p75 compared with healthy controls (P < .0001 for both receptors). The levels of both soluble receptors correlated with simultaneously measured immunoreactive TNF concentrations (p55: r = .63, P < .01; p75: r = .69, P < .001). In the chimpanzees, endotoxin induced subsequent rises in the serum concentrations ofTNF and sTNFRs. Although pentoxifylline reduced the TNF response to intravenous endotoxin to 20% (P < .05), the appearance of sTNFRs was only moderately inhibited (sTNFR-p55 to 79% on average, P < .05; sTNFR-p75 to 77%, P = .12). These results indicate that TNF either does not play an important role in the appearance of sTNFRs in systemic infection or that a small amount ofTNF remaining in the circulation after some bacterial challenges is sufficient to preserve the secretion of its soluble receptor

Prognosis in hypertrophic cardiomyopathy observed in a large clinic population

Overall annual cardiac mortality in hypertrophic cardiomyopathy (HC) has been reported to be between 2 and 4%, although these numbers are primarily from retrospective studies of patients referred to large research institutions. A clinic population of 113 patients with HC was prospectively studied to assess cardiac mortality in the overall group and in selected subgroups commonly thought to be at high risk for sudden death. The mean age at diagnosis was 37 ± 16 years. During follow-up, there were 11 cardiac and 2 noncardiac deaths. The annual cardiac mortality was 1% (95% confidence interval 0.2–1.8%). Because of the small number of deaths, relative risk for cardiac death was not significantly different in the presence of young age (≤30 years), family history of HC and sudden death, history of syncope or previous cardiac arrest, or both, ventricular tachycardia on 24-hour Holter monitoring, or septal myotomy/myectomy for refractory symptoms and outflow tract obstruction. It is concluded that HC has a relatively benign prognosis (1% annual cardiac mortality) that is 2 to 4 times less than that previously reported

Modeling and simulation of phase-transitions in multicomponent aluminum alloy casting

The casting process of aluminum products involves the spatial distribution of alloying elements. It is essential that these elements are uniformly distributed in order to guarantee reliable and consistent products. This requires a good understanding of the main physical mechanisms that affect the solidification, in particular the thermodynamic description and its coupling to the transport processes of heat and mass that take place. The continuum modeling is reviewed and methods for handling the thermodynamics component of multi-element alloys are proposed. Savings in data-storage and computing costs on the order of 100 or more appear possible, when a combination of data-reduction and data-representation methods is used. To test the new approach a simplified model was proposed and shown to qualitatively capture the evolving solidification front

Proving Craig and Lyndon Interpolation Using Labelled Sequent Calculi

We have recently presented a general method of proving the fundamental logical properties of Craig and Lyndon Interpolation (IPs) by induction on derivations in a wide class of internal sequent calculi, including sequents, hypersequents, and nested sequents. Here we adapt the method to a more general external formalism of labelled sequents and provide sufficient criteria on the Kripke-frame characterization of a logic that guarantee the IPs. In particular, we show that classes of frames definable by quantifier-free Horn formulas correspond to logics with the IPs. These criteria capture the modal cube and the infinite family of transitive Geach logics