478 research outputs found
Ecotoxicologische Ernstig Risico Concentraties voor bodem, sediment en (grond)water: herziene voorstellen voor de eerste serie stoffen. Annex
This annex is supplementary to RIVM report 711701020, 'Ecotoxicological Serious Risk Concentrations for soil, sediment and (ground)water: updated proposals for first series of compounds' (E.M.J. Verbruggen, R. Posthumus and A.P. van Wezel). For the compounds considered in this report, which were not yet evaluated in the context of the project 'Setting Integrated Environmental Quality Standards', new toxicity data have been searched for. Further, additional toxicity data were collected for chlorophenols. These toxicity data are incorporated in this annex. The data are single species toxicity data for terrestrial and aquatic organisms and effect data on terrestrial processes. All toxicity data on aquatic and terrestrial organisms refer to effects that may affect the species at the population level
A method to detect baseline emission and plant damage induced volatile emission in a greenhouse
The objective of this research was to ascertain if 1) baseline emission and 2) damage induced emission of volatile plant substances could be detected under greenhouse conditions. A laboratory method was validated for analysing the air in a semi-closed greenhouse with 44 m2 floor area. This greenhouse, with a volume of 270 m3, was climate controlled and light was supplied with assimilation lamps. Sixty tomato plants (Lycopersicon esculentum Mill cv. Moneymaker) were grown in this greenhouse. These plants were artificially damaged on a weekly interval by stroking the stems. Continuous flow pumps were used to purge the air surrounding the plants through tubes containing an adsorbent. This sampling step was performed before and directly after damage of the plants. After sampling, the tubes were transferred to the lab for analysis. The analysis of volatile compounds was performed using a high-throughput gas chromatography-mass spectrometry system. The method enabled the detection of baseline level emission and the emission of volatiles released after artificially damaging the tomato plants during a 6 weeks growing period. Most dominant compounds for baseline emission were the monoterpenes Ăź-phellandrene, 2-carene, limonene, Âż-phellandrene and Âż-pinene. Directly after damage, these compounds showed an increase of up to 100 times compared to baseline level emission. With these results, we prove that it is possible to detect baseline- and plant damage induced volatile emission in a greenhouse. This area of research is promising but more research needs to be done to determine whether it is possible to detect plant damage due to pests and pathogens using volatile sensing
Ecotoxicologische Ernstig Risico Concentraties voor bodem, sediment en (grond)water: herziene voorstellen voor de eerste serie stoffen
The Intervention Value for soil and groundwater is based on the integration of a separately derived human toxicological Serious Risk Concentration or SRChuman as well as an ecotoxicological Serious Risk Concentration or SRCeco. This report presents proposals for updated SRCseco for the first series of compounds. For substances for which MPCs/NCs have been derived between 1990 and now, the same data are used to derive the SRCeco. Together with the derivation of the SRCeco, also a new MPC is derived, according the most recent guidelines as summarised in this report. The information in this report is used in the technical evaluation of Intervention Values for soil, sediment and groundwater, RIVM report 711701 023.De Interventiewaarde voor bodem, sediment en grondwater is gebaseerd op een integratie van onafhankelijk afgeleide humaan toxicologische Ernstig Risico Concentraties of SRChuman en ecotoxicologische Ernstig Risico Concentraties of SRCeco. Dit rapport presenteert voorstellen voor herziene SRCeco voor de eerste serie stoffen. Voor stoffen, waarvoor MTRs/VRs zijn afgeleid tussen 1990 en nu, zijn dezelfde gegevens gebruikt om de SRCeco af te leiden. Samen met de afleiding van de SRCeco is ook een nieuwe MTR waarde afgeleid, in overeenstemming met de meest recente richtlijnen, zoals samengevat in dit rapport. De informatie in dit rapport wordt gebruikt in de technische evaluatie van de Interventiewaarden voorbodem, sediment en grondwater, RIVM rapport 711701 023
The propensity of molecules to spatially align in intense light fields
The propensity of molecules to spatially align along the polarization vector
of intense, pulsed light fields is related to readily-accessible parameters
(molecular polarizabilities, moment of inertia, peak intensity of the light and
its pulse duration). Predictions can now be made of which molecules can be
spatially aligned, and under what circumstances, upon irradiation by intense
light. Accounting for both enhanced ionization and hyperpolarizability, it is
shown that {\it all} molecules can be aligned, even those with the smallest
static polarizability, when subjected to the shortest available laser pulses
(of sufficient intensity).Comment: 8 pages, 4 figures, to be submitted to PR
Irradiation of benzene molecules by ion-induced and light-induced intense fields
Benzene, with its sea of delocalized -electrons in the valence orbitals,
is identified as an example of a class of molecules that enable establishment
of the correspondence between intense ion-induced and laser-light-induced
fields in experiments that probe ionization dynamics in temporal regimes
spanning the attosecond and picosecond ranges.Comment: 4 ps figure
How to observe the Efimov effect
We propose to observe the Efimov effect experimentally by applying an
external electric field on atomic three-body systems. We first derive the
lowest order effective two-body interaction for two spin zero atoms in the
field. Then we solve the three-body problem and search for the extreme
spatially extended Efimov states. We use helium trimers as an illustrative
numerical example and estimate the necessary field strength to be less than 2.7
V/angstrom.Comment: 4 pages, 2 postscript figures, psfig.sty, revte
Exact field ionization rates in the barrier suppression-regime from numerical TDSE calculations
Numerically determined ionization rates for the field ionization of atomic
hydrogen in strong and short laser pulses are presented. The laser pulse
intensity reaches the so-called "barrier suppression ionization" regime where
field ionization occurs within a few half laser cycles. Comparison of our
numerical results with analytical theories frequently used shows poor
agreement. An empirical formula for the "barrier suppression ionization"-rate
is presented. This rate reproduces very well the course of the numerically
determined ground state populations for laser pulses with different length,
shape, amplitude, and frequency.
Number(s): 32.80.RmComment: Enlarged and newly revised version, 22 pages (REVTeX) + 8 figures in
ps-format, submitted for publication to Physical Review A, WWW:
http://www.physik.tu-darmstadt.de/tqe
Correlation dynamics between electrons and ions in the fragmentation of D molecules by short laser pulses
We studied the recollision dynamics between the electrons and D ions
following the tunneling ionization of D molecules in an intense short pulse
laser field. The returning electron collisionally excites the D ion to
excited electronic states from there D can dissociate or be further
ionized by the laser field, resulting in D + D or D + D,
respectively. We modeled the fragmentation dynamics and calculated the
resulting kinetic energy spectrum of D to compare with recent experiments.
Since the recollision time is locked to the tunneling ionization time which
occurs only within fraction of an optical cycle, the peaks in the D kinetic
energy spectra provides a measure of the time when the recollision occurs. This
collision dynamics forms the basis of the molecular clock where the clock can
be read with attosecond precision, as first proposed by Corkum and coworkers.
By analyzing each of the elementary processes leading to the fragmentation
quantitatively, we identified how the molecular clock is to be read from the
measured kinetic energy spectra of D and what laser parameters be used in
order to measure the clock more accurately.Comment: 13 pages with 14 figure
COL5A1 gene variants previously associated with reduced soft tissue injury risk are associated with elite athlete status in rugby.
BACKGROUND: Two common single nucleotide polymorphisms within the COL5A1 gene (SNPs; rs12722 C/T and rs3196378 C/A) have previously been associated with tendon and ligament pathologies. Given the high incidence of tendon and ligament injuries in elite rugby athletes, we hypothesised that both SNPs would be associated with career success. RESULTS: In 1105 participants (RugbyGene project), comprising 460 elite rugby union (RU), 88 elite rugby league athletes and 565 non-athlete controls, DNA was collected and genotyped for the COL5A1 rs12722 and rs3196378 variants using real-time PCR. For rs12722, the injury-protective CC genotype and C allele were more common in all athletes (21% and 47%, respectively) and RU athletes (22% and 48%) than in controls (16% and 41%, P ≤ 0.01). For rs3196378, the CC genotype and C allele were overrepresented in all athletes (23% and 48%) and RU athletes (24% and 49%) compared with controls (16% and 41%, P ≤ 0.02). The CC genotype in particular was overrepresented in the back and centres (24%) compared with controls, with more than twice the odds (OR = 2.25, P = 0.006) of possessing the injury-protective CC genotype. Furthermore, when considering both SNPs simultaneously, the CC-CC SNP-SNP combination and C-C inferred allele combination were higher in all the athlete groups (≥18% and ≥43%) compared with controls (13% and 40%; P = 0.01). However, no genotype differences were identified for either SNP when RU playing positions were compared directly with each other. CONCLUSION: It appears that the C alleles, CC genotypes and resulting combinations of both rs12722 and rs3196378 are beneficial for rugby athletes to achieve elite status and carriage of these variants may impart an inherited resistance against soft tissue injury, despite exposure to the high-risk environment of elite rugby. These data have implications for the management of inter-individual differences in injury risk amongst elite athletes
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