231 research outputs found
Regional priorities for strengthening climate services for farmers in Africa and South Asia
This report captures a process of shared South-South learning and planning towards defining
priorities for strengthening and scaling-up climate information and advisory services for
agriculture and food security in West Africa, Eastern and Southern Africa, and South Asia.
The process began at the international workshop on âScaling up Climate Services for Farmers
in Africa and South Asiaâ (Saly, Senegal, December 2012), where participants collectively
identified critical gaps in the design, delivery and effective use of climate services for
smallholder agriculture; and self-organized into working groups to develop a set of priority
actions for strengthening climate services for smallholder farming communities within and
across regions in sub-Saharan Africa and South Asia. Following up on a commitment made
at the workshop, USAID and CCAFS partnered to develop a small grants program and
sponsor a set of guided planning workshops to enable the working groups that emerged from
the Saly workshop to further develop their visions, and obtain resources to begin to
implement them. Expert working groups from all regions prioritized improving the scientific
capacity of National Meteorological and Hydrological Services (NMHSs) to develop location
specific seasonal climate forecasts at the subnational scale, and enhancing institutional
frameworks for collaboration between the different agencies involved in the production and
communication of climate services. The Eastern and Southern Africa working group also
emphasized the co-production with farmers of location-specific climate services, and the
importance of assessing the added value of climate services for enhancing agricultural
production and managing risk. The West Africa working group prioritized communications
mechanisms for reaching marginalized groups, including rural radio and Information and
Communications Technologies (ICTs), and training farmers to access and use climate
information. Building on the regionâs existing strength in ICTs, the South Asia group
emphasized efforts to identify appropriate ICT tools and build the capacity of smallholder
farmers, women, poor and socially marginalized groups to access and utilize climate
information services
Faraday rotation spectra of bismuth-substituted ferrite garnet films with in-plane magnetization
Single crystalline films of bismuth-substituted ferrite garnets have been
synthesized by the liquid phase epitaxy method where GGG substrates are dipped
into the flux. The growth parameters are controlled to obtain films with
in-plane magnetization and virtually no domain activity, which makes them
excellently suited for magnetooptic imaging. The Faraday rotation spectra were
measured across the visible range of wavelengths. To interprete the spectra we
present a simple model based on the existence of two optical transitions of
diamagnetic character, one tetrahedral and one octahedral. We find excellent
agreement between the model and our experimental results for photon energies
between 1.77 and 2.53 eV, corresponding to wavelengths between 700 and 490 nm.
It is shown that the Faraday rotation changes significantly with the amount of
substituted gallium and bismuth. Furthermore, the experimental results suggest
that the magnetooptic response changes linearly with the bismuth substitution.Comment: 15 pages, 6 figures, published in Phys. Rev.
Fatty Acid Methyl Esters as Biosolvents of Epoxy Resins: A Physicochemical Study
The C8 to C18 fatty acid methyl esters (FAME) have been compared as solvents for two epoxy resin pre-polymers, bisphenol A diglycidyl ether (DGEBA) and triglycidyl paminophenol ether (TGPA). It was found that the solubilization limits vary according to the ester and that methyl caprylate is the best solvent of both resins. To explain these solubility performances, physical and chemical properties of FAME were studied, such as the Hansen parameters, viscosity, binary diffusion coefficient and vaporization enthalpy. Determination of the physicochemical parameters of FAME was carried out by laboratory experimentations and by calculation from bibliographic data. The Hansen parameters of FAME and epoxy resins pre-polymers were theoretically and experimentally determined. The FAME chain length showed a long dependence on the binary diffusion parameters and kinematic viscosity, which are mass and momentum transport properties. Moreover, the vaporization enthalpy of these compounds was directly correlated with the solubilization limits
Geotomography with solar and supernova neutrinos
We show how by studying the Earth matter effect on oscillations of solar and
supernova neutrinos inside the Earth one can in principle reconstruct the
electron number density profile of the Earth. A direct inversion of the
oscillation problem is possible due to the existence of a very simple analytic
formula for the Earth matter effect on oscillations of solar and supernova
neutrinos. From the point of view of the Earth tomography, these oscillations
have a number of advantages over the oscillations of the accelerator or
atmospheric neutrinos, which stem from the fact that solar and supernova
neutrinos are coming to the Earth as mass eigenstates rather than flavour
eigenstates. In particular, this allows reconstruction of density profiles even
over relatively short neutrino path lengths in the Earth, and also of
asymmetric profiles. We study the requirements that future experiments must
meet to achieve a given accuracy of the tomography of the Earth.Comment: 35 pages, 7 figures; minor textual changes in section
Large-scale pathways-based association study in amyotrophic lateral sclerosis
Sporadic amyotrophic lateral sclerosis (ALS), a devastating neurodegenerative disease, most likely results from complex genetic and environmental interactions. Although a number of association studies have been performed in an effort to find genetic components of sporadic ALS, most of them resulted in inconsistent findings due to a small number of genes investigated in relatively small sample sizes, while the replication of results was rarely attempted. Defects in retrograde axonal transport, vesicle trafficking and xenobiotic metabolism have been implicated in neurodegeneration and motor neuron death both in human disease and animal models. To assess the role of common genetic variation in these pathways in susceptibility to sporadic ALS, we performed a pathway-based candidate gene case-control association study with replication. Furthermore, we determined reliability of whole genome amplified DNA in a large-scale association study. In the first stage of the study, 1277 putative functional and tagging SNPs in 134 genes spanning 8.7 Mb were genotyped in 822 British sporadic ALS patients and 872 controls using whole genome amplified DNA. To detect variants with modest effect size and discriminate among false positive findings 19 SNPs showing a trend of association in the initial screen were genotyped in a replication sample of 580 German sporadic ALS patients and 361 controls. We did not detect strong evidence of association with any of the genes investigated in the discovery sample (lowest uncorrected P-value 0.00037, lowest permutation corrected P-value 0.353). None of the suggestive associations was replicated in a second sample, further excluding variants with moderate effect size. We conclude that common variation in the investigated pathways is unlikely to have a major effect on susceptibility to sporadic ALS. The genotyping efficiency was only slightly decreased (âŒ1%) and genotyping quality was not affected using whole genome amplified DNA. It is reliable for large scale genotyping studies of diseases such as ALS, where DNA sample collections are limited because of low disease prevalence and short survival time. © 2007 The Author(s)
Anaerobic digestion of screenings for biogas recovery
Screenings comprise untreatable solid materials that have found their way into the sewer. They are removed during preliminary treatment at the inlet work of any wastewater treatment process using a unit operation termed as a screen and at present are disposed of to landfill. These materials, if not removed, will damage mechanical equipment due to its heterogeneity and reduce overall treatment process, reliability and effectiveness. That is why this material is retained and prevented from entering the treatment system before finally being disposed of. The amount of biodegradable organic matter in screenings often exceeds the upper limit and emits a significant amount of greenhouse gases during biodegradation on landfill. Nutrient release can cause a serious problem of eutrophication phenomena in receiving waters and a deterioration of water quality. Disposal of screenings on landfill also can cause odour problem due to putrescible nature of some of the solid material. In view of the high organic content of screenings, anaerobic digestion method may not only offer the potential for energy recovery but also nutrient. In this study, the anaerobic digestion was performed for 30,days, at controlled pH and temperature, using different dry solids concentrations of screenings to study the potential of biogas recovery in the form of methane. It was found screenings have physical characteristics of 30% total solids and 93% volatile solids, suggesting screenings are a type of waste with high dry solids and organic contents. Consistent pH around pH 6.22 indicates anaerobic digestion of screenings needs minimum pH correction. The biomethane potential tests demonstrated screenings were amenable to anaerobic digestion with methane yield of 355,m3/kg VS, which is comparable to the previous results. This study shows that anaerobic digestion is not only beneficial for waste treatment but also to turn waste into useful resources
Direct radiative forcing and atmospheric absorption by boundary layer aerosols in the southeastern US: model estimates on the basis of new observations
In an effort to reduce uncertainties in the quantification of aerosol direct radiative forcing (ADRF) in the southeastern United States (US), a field column experiment was conducted to measure aerosol radiative properties and effects at Mt. Mitchell, North Carolina, and at an adjacent valley site. The experimental period was from June 1995 to mid-December 1995. The aerosol optical properties (single scattering albedo and asymmetry factor) needed to compute ADRF were obtained on the basis of a procedure involving a Mie code and a radiative transfer code in conjunction with the retrieved aerosol size distribution, aerosol optical depth, and diffuse-to-direct solar irradiance ratio. The regional values of ADRF at the surface and top of atmosphere (TOA), and atmospheric aerosol absorption are derived using the obtained aerosol optical properties as inputs to the column radiation model (CRM) of the community climate model (CCM3). The cloud-free instantaneous TOA ADRFs for highly polluted (HP), marine (M) and continental (C) air masses range from 20.3 to â24.8, 1.3 to â10.4, and 1.9 to â13.4 W mâ2, respectively. The mean cloud-free 24-h ADRFs at the TOA (at the surface) for HP, M, and C air masses are estimated to be â8±4 (â33±16), â7±4 (â13±8), and â0.14±0.05 (â8±3) W mâ2, respectively. On the assumption that the fractional coverage of clouds is 0.61, the annual mean ADRFs at the TOA and the surface are â2±1, and â7±2 W mâ2, respectively. This also implies that aerosols currently heat the atmosphere over the southeastern US by 5±3 W mâ2 on annual timescales due to the aerosol absorption in the troposphere
Path to AWAKE : evolution of the concept
This paper describes the conceptual steps in reaching the design of the AWAKE experiment currently under construction at CERN. We start with an introduction to plasma wakefield acceleration and the motivation for using proton drivers. We then describe the self-modulation instability - a key to an early realization of the concept. This is then followed by the historical development of the experimental design, where the critical issues that arose and their solutions are described. We conclude with the design of the experiment as it is being realized at CERN and some words on the future outlook. A summary of the AWAKE design and construction status as presented in this conference is given in Gschwendtner et al. [1]
SOIL ATTRIBUTES THREE YEARS AFTER MAKING RIDGES AND OR DRAINS FOR PLANTING GRAPEVINE ROOTSTOCK
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