23,071 research outputs found
Experimental study of factors influencing the risk of drift from field sprayers Part 2: Spray application technique.
Recently, spray drift and its effects have become an important aspect of risk assessment in the registration process of pesticides in Belgium. In this regulation, drift reducing spray application techniques can be used to reduce buffer zones. The purpose of this research is to measure and compare the amount of drift sediment for different spray application techniques under field conditions. A drift prediction equation for the reference spraying was used to compare other spraying techniques with the reference spraying, under different weather conditions. Drift measurements were performed for several combinations of nozzle type (flat fan, low-drift, air injection) and size (ISO 02, 03, 04 and 06), spray pressure (2, 3 and 4 bar), driving speed (4, 6, 8 and 10 km.h-1) and spray boom height (0.3, 0.5 and 0.75 m). Nozzle type as well as spray pressure, driving speed and spray boom height, have an important effect on the amount of spray drift. Larger nozzle sizes, lower spray pressures and driving speeds and lower spray boom heights generally reduce spray drift. Concerning nozzle types, air injection nozzles have the highest drift reduction potential followed by the low-drift nozzles and the standard flat fan nozzles
Considerations on grapevine selection and certification
Different viruses and virus-like diseases can be detrimental to grapevines and their products. The protocols of the assays used to evaluate the impact of viruses have evolved with the progress of the knowledge in aetiology and diagnosis. A wrong interpretation of the data from experiments that compare the performance of virus-infected and non-infected vines may lead to erroneous conclusions. Even if some experiments show that virus infections induce an increase of sugar content, a better evaluation of the experimental data may show that the conclusion drawn is incorrect. The role viruses may play in clonal variability is also discussed
Gateway Modeling and Simulation Plan
This plan institutes direction across the Gateway Program and the Element Projects to ensure that Cross Program M&S are produced in a manner that (1) generate the artifacts required for NASA-STD-7009 compliance, (2) ensures interoperability of M&S exchanged and integrated across the program and, (3) drives integrated development efforts to provide cross-domain integrated simulation of the Gateway elements, space environment, and operational scenarios. This direction is flowed down via contractual enforcement to prime contractors and includes both the GMS requirements specified in this plan and the NASASTD- 7009 derived requirements necessary for compliance. Grounding principles for management of Gateway Models and Simulations (M&S) are derived from the Columbia Accident Investigation Board (CAIB) report and the Diaz team report, A Renewed Commitment to Excellence. As an outcome of these reports, and in response to Action 4 of the Diaz team report, the NASA Standard for Models and Simulations, NASA-STD-7009 was developed. The standard establishes M&S requirements for development and use activities to ensure proper capture and communication of M&S pedigree and credibility information to Gateway program decision makers. Through the course of the Gateway program life cycle M&S will be heavily relied upon to conduct analysis, test products, support operations activities, enable informed decision making and ultimately to certify the Gateway with an acceptable level of risk to crew and mission. To reduce risk associated with M&S influenced decisions, this plan applies the NASA-STD-7009 requirements to produce the artifacts that support credibility assessments and ensure the information is communicated to program management
Somatic embryogenesis from stem nodal sections of grapevine
Indirect somatic embryogenesis was obtained for 11 clones of 6 Vitis vinifera cultivars: Cabernet-Sauvignon, Chardonnay, Gewürztraminer, Grenache, Merlot and Sauvignon, and for the rootstock Fercal [(Vitis berlandieri x Vitis colombard) x (Vitis vinifera x Vitis berlandieri)], starting from vegetative explants of in vitro plantlets. Embryogenic callus was recovered from nodal explants of every tested clone, while leaf explants led to embryogenesis only for the rootstock Fercal. We thus showed that axillary bud microcuttings are valuable explants for inducing somatic embryogenesis in V. vinifera and Fercal. Embryogenic cell lines have been maintained through secondary embryogenesis, and some embryos were converted into whole plantlets. A complete protocol for somatic embryogenesis and plant regeneration was therefore designed, using this very simple method.
A survey of grapevine fanleaf nepovirus isolates for the presence of satellite RNA
Grapevine fanleaf virus (GFLV) isolates from different geographical origins were surveyed for natural occurrence of satellite RNA. The results of molecular hybridization assays indicated that 5 isolates out of 34 tested, support the multiplication of a satellite RNA, both in Chenopodium quinoa and grapevine. The satellite molecules appear to have a high degree of sequence homology with, and the same size of, the satellite RNA supported by GFLV-F13 strain, isolated and characterized in France
Pharmacotherapy for weight loss: the cardiovascular effects of the old and new agents
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108287/1/jcpt12177.pd
Modulus Stabilization with Bulk Fields
We propose a mechanism for stabilizing the size of the extra dimension in the
Randall-Sundrum scenario. The potential for the modulus field that sets the
size of the fifth dimension is generated by a bulk scalar with quartic
interactions localized on the two 3-branes. The minimum of this potential
yields a compactification scale that solves the hierarchy problem without fine
tuning of parameters.Comment: 8 pages, LaTeX; minor typo correcte
What is the right theory for Anderson localization of light?
Anderson localization of light is traditionally described in analogy to
electrons in a random potential. Within this description the disorder strength
-- and hence the localization characteristics -- depends strongly on the
wavelength of the incident light. In an alternative description in analogy to
sound waves in a material with spatially fluctuating elastic moduli this is not
the case. Here, we report on an experimentum crucis in order to investigate the
validity of the two conflicting theories using transverse-localized optical
devices. We do not find any dependence of the observed localization radii on
the light wavelength. We conclude that the modulus-type description is the
correct one and not the potential-type one. We corroborate this by showing that
in the derivation of the traditional, potential-type theory a term in the wave
equation has been tacititly neglected. In our new modulus-type theory the wave
equation is exact. We check the consistency of the new theory with our data
using a field-theoretical approach (nonlinear sigma model)
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