249 research outputs found
Benodigde destructiecapaciteit bij de bestrijding van besmettelijke dierziekten in Nederland
In deze notitie tracht men de omvang te bepalen van het aan te bieden destructiemateriaal op enig moment in de toekomst als gevolg van een dierziektebestrijding. Belangrijk is niet zozeer de totale hoeveelheid, maar de maximale hoeveelheid per week die moet worden verwerkt. Resultaten zijn geven voor Afrikaanse varkenspest, aviaire influenza en mond en klauwzee
Sleep restriction and serving accuracy in performance tennis players, and effects of caffeine
This is the authorās version of a work that was accepted for publication in Physiology and Behavior. In its present form it has the following title: 'Sleep restriction, serving accuracy in performance tennis players, and effects of caffeine'. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published at: http://dx.doi.org/10.1016/j.physbeh.2013.07.002.Athletes often lose sleep on the night before a competition. Whilst it is unlikely that sleep loss will
impair sports mostly relying on strength and endurance, little is known about potential effects on
sports involving psychomotor performance requiring high level cognitive skills necessitating
judgement and accuracy, as in tennis, and where caffeine is āpermittedāā. Two studies were
undertaken on the effects of 5h sleep (33%) restriction versus normal sleep, on an objective
measure of serving accuracy in semi-professional tennis players. Testing (14:00h-16:00h) for
both studies comprised 40 serves into a (1.8m x 1.1m) āservice boxā diagonally, over the net.
Study 2 was identical to that of Study 1, except that there was an extra sleep restriction condition.
All conditions involved a sugar free drink given 30 min before testing, but with the drink for one
sleep restriction containing 80mg caffeine (double blind). Study 1 comprised 16 men and
women, in a within Ss counterbalanced design (normal versus sleep restriction). Study 2
involved 12 different men and women undergoing three conditions in a latin square design.
Conditions were as for Study 1, with a replicated sleep restriction. All conditions incorporated a
sugar-free drink given 30 min before testing, with one restriction including 80mg caffeine (double
blind). Both studies showed significant impairments to serving accuracy following sleep
restriction, particularly with women. At this dose, caffeine had no beneficial effect. These results
reflect laboratory based, non-sports related findings pointing to detrimental effects of sleep loss
on executive function
Synthetic- and bio-polymer use for runoff water quality management in irrigation agriculture
Low concentrations of synthetic- or bio-polymers in irrigation water can nearly eliminate
sediment, N, ortho- and total-P, DOM, pesticides, micro-organisms, and weed seed from runoff. These
environmentally safe polymers are employed in various sensitive uses including food processing, animal
feeds, and potable water purification. The most common synthetic polymer is anionic, high purity
polyacrylamide (PAM), which typically provides 70-90% contaminant elimination. Excellent results are
achieved adding only 10 ppm PAM to irrigation water, applying 1 -2 kg ha. -1 per irrigation, costing
12 kg -1 . Biopolymers are less effective. Using twice or higher concentrations, existing biopolymers
are ,r=60% effective as PAM, at 2 - 3 times the cost. A half million ha of US irrigated land use PAM for
erosion control and runoff protection. The practice is spreading rapidly in the US and worldwide. Interest
in development of biopolymer surrogates for PAM is high. If the supply of cheap natural gas (raw material
for PAM synthesis) diminishes, industries may seek alternative polymers. Also "green" perceptions and
preferences favor biopolymers for certain application
Synthetic- and Bio-polymer use for runoff water quality management in irrigated agriculture
Low concentrations of synthetic- or bio-polymers in irrigation water can nearly eliminate sediment, N,
ortho- and total-P, DOM, pesticides, micro-organisms, and weed seed from runoff. These environmentally safe
polymers are employed in various sensitive uses including food processing, animal feeds, and potable water
purification. The most common synthetic polymer is anionic, high purity polyacrylamide (PAM), which typically
provides 70-90% contaminant elimination. Excellent results are achieved adding only 10 ppm PAM to irrigation
water, applying 1-2 kg ha-lper irrigation, costing 12 kg-1. Biopolymers are less effective, but show promise; they
include starch co-polymers, microfibril suspensions, chitin, polysaccharides and protein derivatives. Using twice or
higher concentrations, existing biopolymers are ~60% effective as PAM, at 2-3 times the cost kg-1. A half million ha
of US irrigated land use PAM for erosion control and runoff protection. The practice is spreading rapidly in the US
and worldwide. Interest in development of biopolymer surrogates for PAM is high. If the supply of cheap natural gas
(raw material for PAM synthesis) diminishes, industries may seek alternative polymers. Also "green" perceptions and
preferences favor biopolymers for certain applications. More complete history, user/technical information and
bibliography are found at
Anthropogenic Space Weather
Anthropogenic effects on the space environment started in the late 19th
century and reached their peak in the 1960s when high-altitude nuclear
explosions were carried out by the USA and the Soviet Union. These explosions
created artificial radiation belts near Earth that resulted in major damages to
several satellites. Another, unexpected impact of the high-altitude nuclear
tests was the electromagnetic pulse (EMP) that can have devastating effects
over a large geographic area (as large as the continental United States). Other
anthropogenic impacts on the space environment include chemical release ex-
periments, high-frequency wave heating of the ionosphere and the interaction of
VLF waves with the radiation belts. This paper reviews the fundamental physical
process behind these phenomena and discusses the observations of their impacts.Comment: 71 pages, 35 figure
Observations of quasi-periodic solar X-ray emission as a result of MHD oscillations in a system of multiple flare loops
We investigate the solar flare of 20 October 2002. The flare was accompanied
by quasi-periodic pulsations (QPP) of both thermal and nonthermal hard X-ray
emissions (HXR) observed by RHESSI in the 3-50 keV energy range. Analysis of
the HXR time profiles in different energy channels made with the Lomb
periodogram indicates two statistically significant time periods of about 16
and 36 seconds. The 36-second QPP were observed only in the nonthermal HXR
emission in the impulsive phase of the flare. The 16-second QPP were more
pronounced in the thermal HXR emission and were observed both in the impulsive
and in the decay phases of the flare. Imaging analysis of the flare region, the
determined time periods of the QPP and the estimated physical parameters of
magnetic loops in the flare region allow us to interpret the observations as
follows. 1) In the impulsive phase energy was released and electrons were
accelerated by successive acts with the average time period of about 36 seconds
in different parts of two spatially separated, but interacting loop systems of
the flare region. 2) The 36-second periodicity of energy release could be
caused by the action of fast MHD oscillations in the loops connecting these
flaring sites. 3) During the first explosive acts of energy release the MHD
oscillations (most probably the sausage mode) with time period of 16 seconds
were excited in one system of the flare loops. 4) These oscillations were
maintained by the subsequent explosive acts of energy release in the impulsive
phase and were completely damped in the decay phase of the flare.Comment: 14 pages, 4 figure
Characterizing RadiationāBelt Energetic Electron Precipitation Spectra: A Comparison of QuasiāLinear Diffusion Theory With In Situ Measurements
High energy electron precipitation from the Earth's radiation belts is important for loss from the radiation belts and atmospheric chemistry. We follow up investigations presented in Reidy et al. (2021, https://doi.org/10.1029/2020ja028410) where precipitating flux is calculated inside the field of view of the POES T0 detector using quasi-linear theory and pitch angle diffusion coefficients (DĪ±Ī±) from the British Antarctic Survey (BAS). These results showed good agreements at >30 keV for L* >5 on the dawnside but the flux were too low at higher energies. We have investigated the effect of changing parameters in the calculation of the precipitating flux to improve the results for the higher energies using comparisons of in situ flux and cold plasma measurements from GOES-15 and RBSP. We find that the strength of the diffusion coefficients rather than the shape of the source spectrum has the biggest effect on the calculated precipitation. In particular we find decreasing the cold plasma density used in the calculation of DĪ±Ī± increases the diffusion and hence the precipitation at the loss cone for the higher energies, improving our results. The method of calculating DĪ±Ī± is also examined, comparing co-located rather than averaged RBSP measurements. We find that the method itself has minimal effect but using RBSP derived DĪ±Ī± improved our results over using DĪ±Ī± calculated using the entire BAS wave data base; this is potentially due to better measurements of the cold plasma density from RBSP than the other spacecraft included in the BAS wave data base (e.g., THEMIS)
Active Galaxies in the UV
In this article we present different aspects of AGN studies demonstrating the
importance of the UV spectral range. Most important diagnostic lines for
studying the general physical conditions as well as the metalicities in the
central broad line region in AGN are emitted in the UV. The UV/FUV continuum in
AGN excites not only the emission lines in the immediate surrounding but it is
responsible for the ionization of the intergalactic medium in the early stages
of the universe. Variability studies of the emission line profiles of AGN in
the UV give us information on the structure and kinematics of the immediate
surrounding of the central supermassive black hole as well as on its mass
itself.Comment: 29 pages, 13 figures, Ap&SS in pres
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