48 research outputs found
Suitability of pesticide risk indicators for less developed countries: a comparison
Pesticide risk indicators provide simple support in the assessment of environmental and health risks
from pesticide use, and can therefore inform policies to foster a sustainable interaction of agriculture
with the environment. For their relative simplicity, indicators may be particularly useful under conditions
of limited data availability and resources, such as in Less Developed Countries (LDCs). However,
indicator complexity can vary significantly, in particular between those that rely on an exposure–toxicity
ratio (ETR) and those that do not. In addition, pesticide risk indicators are usually developed for Western
contexts, which might cause incorrect estimation in LDCs. This study investigated the appropriateness
of seven pesticide risk indicators for use in LDCs, with reference to smallholding agriculture in Colombia.
Seven farm-level indicators, among which 3 relied on an ETR (POCER, EPRIP, PIRI) and 4 on a non-ETR
approach (EIQ, PestScreen, OHRI, Dosemeci et al., 2002), were calculated and then compared by means
of the Spearman rank correlation test. Indicators were also compared with respect to key indicator characteristics,
i.e. user friendliness and ability to represent the system under study. The comparison of the
indicators in terms of the total environmental risk suggests that the indicators not relying on an ETR
approach cannot be used as a reliable proxy for more complex, i.e. ETR, indicators. ETR indicators, when
user-friendly, show a comparative advantage over non-ETR in best combining the need for a relatively
simple tool to be used in contexts of limited data availability and resources, and for a reliable estimation
of environmental risk. Non-ETR indicators remain useful and accessible tools to discriminate between
different pesticides prior to application. Concerning the human health risk, simple algorithms seem more
appropriate for assessing human health risk in LDCs. However, further research on health risk indicators
and their validation under LDC conditions is needed
D* Production in Deep Inelastic Scattering at HERA
This paper presents measurements of D^{*\pm} production in deep inelastic
scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The
data have been taken with the ZEUS detector at HERA. The decay channel
(+ c.c.) has been used in the study. The
cross section for inclusive D^{*\pm} production with
and is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region
{ GeV and }. Differential cross
sections as functions of p_T(D^{*\pm}), and are
compared with next-to-leading order QCD calculations based on the photon-gluon
fusion production mechanism. After an extrapolation of the cross section to the
full kinematic region in p_T(D^{*\pm}) and (D^{*\pm}), the charm
contribution to the proton structure function is
determined for Bjorken between 2 10 and 5 10.Comment: 17 pages including 4 figure
Observation of hard scattering in photoproduction events with a large rapidity gap at HERA
Events with a large rapidity gap and total transverse energy greater than 5
GeV have been observed in quasi-real photoproduction at HERA with the ZEUS
detector. The distribution of these events as a function of the
centre of mass energy is consistent with diffractive scattering. For total
transverse energies above 12 GeV, the hadronic final states show predominantly
a two-jet structure with each jet having a transverse energy greater than 4
GeV. For the two-jet events, little energy flow is found outside the jets. This
observation is consistent with the hard scattering of a quasi-real photon with
a colourless object in the proton.Comment: 19 pages, latex, 4 figures appended as uuencoded fil
Observation of Events with an Energetic Forward Neutron in Deep Inelastic Scattering at HERA
In deep inelastic neutral current scattering of positrons and protons at the center of mass energy of 300 GeV, we observe, with the ZEUS detector, events with a high energy neutron produced at very small scattering angles with respect to the proton direction. The events constitute a fixed fraction of the deep inelastic, neutral current event sample independent of Bjorken x and Q2 in the range 3 · 10-4 \u3c xBJ \u3c 6 · 10-3 and 10 \u3c Q2 \u3c 100 GeV2
The supply of nitrogen and the growth of winter barley
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