4,261 research outputs found
Aanwenden van vaste mest verloopt niet zonder problemen
De moderne mestverspreiders verkleinen en verspreiden de vaste mest relatief goed, maar de kans op insporing vormt een probleem bij vroege aanwending
The effect of a multispecies probiotic on the composition of the faecal microbiota and bowel habits in chronic obstructive pulmonary disease patients treated with antibiotics
Short-term antibiotic treatment profoundly affects the intestinal microbiota, which may lead to sustained changes in microbiota composition. Probiotics may restore such a disturbance. The objective of the present study was to investigate the effect of a multispecies probiotic on the faecal microbiota during and after antibiotic intake in patients with a history of frequent antibiotic use. In this randomised, placebo-controlled, double-blind study, thirty chronic obstructive pulmonary disease (COPD) patients treated with antibiotics for a respiratory tract infection received 5 g of a multispecies probiotic or placebo twice daily for 2 weeks. Faecal samples were collected at 0, 7, 14 and 63 d. Changes in the composition of the dominant faecal microbiota were determined by PCR-denaturing gradient gel electrophoresis (DGGE). Changes in bacterial subgroups were determined by quantitative PCR and culture. Bowel movements were scored daily according to the Bristol stool form scale. During and after antibiotic treatment, DGGE-based similarity indices (SI) were high ( >/= 84 %) and band richness was relatively low, both remaining stable over time. No difference in SI was observed between patients with and without diarrhoea-like bowel movements. The multispecies probiotic had a modest effect on the bacterial subgroups. Nevertheless, it affected neither the composition of the dominant faecal microbiota nor the occurrence of diarrhoea-like bowel movements. The dominant faecal microbiota was not affected by antibiotics in this COPD population, suggesting an existing imbalance of the microbiota, which may also have contributed to the lack of effect by probiotic intak
Cavity-enhanced photoionization of an ultracold rubidium beam for application in focused ion beams
A two-step photoionization strategy of an ultracold rubidium beam for
application in a focused ion beam instrument is analyzed and implemented. In
this strategy the atomic beam is partly selected with an aperture after which
the transmitted atoms are ionized in the overlap of a tightly cylindrically
focused excitation laser beam and an ionization laser beam whose power is
enhanced in a build-up cavity. The advantage of this strategy, as compared to
without the use of a build-up cavity, is that higher ionization degrees can be
reached at higher currents. Optical Bloch equations including the
photoionization process are used to calculate what ionization degree and
ionization position distribution can be reached. Furthermore, the ionization
strategy is tested on an ultracold beam of Rb atoms. The beam current is
measured as a function of the excitation and ionization laser beam intensity
and the selection aperture size. Although details are different, the global
trends of the measurements agree well with the calculation. With a selection
aperture diameter of 52 m, a current of pA is
measured, which according to calculations is 63% of the current equivalent of
the transmitted atomic flux. Taking into account the ionization degree the ion
beam peak reduced brightness is estimated at A/(msreV).Comment: 13 pages, 9 figure
Guide for the identification of archaeological sea sturgeon (<i>Acipenser sturio</i> and <i>A. oxyrinchus</i>) remains
Remains of sturgeons (Acipenser sturio and A. oxyrinchus) are regularly found on western European archaeological sites. The identification of these isolated bones should ideally be carried out with the aid of a comparative skeletal collection, consisting of modern specimens of different sizes. Because such reference material of sea sturgeons (A. sturio and A. oxyrinchus) is relatively rare and dispersed over many different museums and institutes, a practical guide is presented here as an aid to the identification of the most commonly found archaeological sturgeon remains. This guide, which is based on observations made on 64 individuals housed in 13 different natural history collections, should allow identifying most archaeological sturgeon remains from western European sites. Presented are the morphological characteristics of the bones of the skull roof and circumorbital region (posttemporal, dermopterotic, parietal, frontal, dermosphenotic, postorbital, jugal and supraorbital), bones of the braincase (parasphenoid), opercular series (subopercle and branchiostegals), the palatoquadrate and associated bones and lower jaw (palatopterygoid, dermopalatine and dentary), the hyoid and gill arches with the hyomandibula, the isolated skeletal elements from the pectoral girdle (clavicle, cleithrum and supracleithrum), the bones of the fin and fin supports (pectoral fin spine, fin rays and fulcra) and the dorsal, ventral, lateral and accessory scutes. For each element, descriptions and pictures are provided of modern and archaeological specimens. Regression equations allowing fish length reconstructions on the basis of single bone measurements are given for 14 elements and the scutes. Finally, criteria for species identification are provided. In the case of the dentary, dermopalatine and palatopterygoid, these are differences in shape of the skeletal elements, whereas for the dermal bones the external surface pattern is diagnostic when reconstructed fish length is over one meter
Laser application to measure vertical sea temperature and turbidity, design phase
An experiment to test a new method was designed, using backscattered radiation from a laser beam to measure oceanographic parameters in a fraction of a second. Tyndall, Rayleigh, Brillouin, and Raman scattering all are utilized to evaluate the parameters. A beam from a continuous argon ion laser is used together with an interferometer and interference filters to gather the information. The results are checked by direct measurements. Future shipboard and airborne experiments are described
The Air-temperature Response to Green/blue-infrastructure Evaluation Tool (TARGET v1.0) : an efficient and user-friendly model of city cooling
The adverse impacts of urban heat and global climate change are leading policymakers to consider green and blue infrastructure (GBI) for heat mitigation benefits. Though many models exist to evaluate the cooling impacts of GBI, their complexity and computational demand leaves most of them largely inaccessible to those without specialist expertise and computing facilities. Here a new model called The Air-temperature Response to Green/blue-infrastructure Evaluation Tool (TARGET) is presented. TARGET is designed to be efficient and easy to use, with fewer user-defined parameters and less model input data required than other urban climate models. TARGET can be used to model average street-level air temperature at canyon-to-block scales (e.g. 100 m resolution), meaning it can be used to assess temperature impacts of suburb-to-city-scale GBI proposals. The model aims to balance realistic representation of physical processes and computation efficiency. An evaluation against two different datasets shows that TARGET can reproduce the magnitude and patterns of both air temperature and surface temperature within suburban environments. To demonstrate the utility of the model for planners and policymakers, the results from two precinct-scale heat mitigation scenarios are presented. TARGET is available to the public, and ongoing development, including a graphical user interface, is planned for future work
Avalanches, breathers, and flow reversal in a continuous Lorenz-96 model
For the discrete model suggested by Lorenz in 1996, a one-dimensional long-wave approximation with nonlinear excitation and diffusion is derived. The model is energy conserving but non-Hamiltonian. In a low-order truncation, weak external forcing of the zonal mean flow induces avalanchelike breather solutions which cause reversal of the mean flow by a wave-mean flow interaction. The mechanism is an outburst-recharge process similar to avalanches in a sandpile model
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