Recognizing and realizing the potential of organic agriculture in Kenya

Formal organic agriculture in Kenya dates back to the early eighties when the first pioneer organic training institutions were established. During the same period, a few horticultural companies started growing organic vegetables for export. Initial efforts to promote organic agriculture in Kenya were made by rural development non-governmental organizations (NGOs), faith based organizations and community based organizations (CBOs). They seek to help rural farmers in addressing the issue of declining agricultural productivity (especially the degradation of soils and natural resource base), high poverty incidences, food insecurity and low incomes which pre-vented farmers from assessing high costs inputs. Currently Kenya has five major players in organic agriculture namely Kitale-based Manor House Agricultural Center, Baraka College in Molo, the Sustainable Agriculture Community Development Pro-gram in Thika, the Kenya Institute of Organic Farming (KIOF), a training center on the outskirts Kenya’s capital Nairobi, and the Association for Better Land Husbandry (ABLH), headquartered in Nairobi. The organic sector is relatively small; however, it is growing very fast, led mainly by NGOs and private sector (companies growing organic produce for export). Exports of organic products have been taking place for the last two decades, mainly with vegetables and fruits produced on large scale farms. Over the years exports have developed beyond vegetables and fruits to include other prod-ucts such as essential oils, dried herbs and spices as well as products for the cos-metic and pharmaceutical industries which are more often produced by smallholders. Currently, there are five international certifiers operating in Kenya, namely: the Soil Association (SA), EcoCert International; IMO (Institute for Market Ecology); USDA’s (United States Department of Agriculture) National Organic Programme (NOP) and Bio Suisse

Intrinsic galaxy shapes and alignments II: Modelling the intrinsic alignment contamination of weak lensing surveys

Intrinsic galaxy alignments constitute the major astrophysical systematic of forthcoming weak gravitational lensing surveys but also yield unique insights into galaxy formation and evolution. We build analytic models for the distribution of galaxy shapes based on halo properties extracted from the Millennium Simulation, differentiating between early- and late-type galaxies as well as central galaxies and satellites. The resulting ellipticity correlations are investigated for their physical properties and compared to a suite of current observations. The best-faring model is then used to predict the intrinsic alignment contamination of planned weak lensing surveys. We find that late-type galaxy models generally have weak intrinsic ellipticity correlations, marginally increasing towards smaller galaxy separation and higher redshift. The signal for early-type models at fixed halo mass strongly increases by three orders of magnitude over two decades in galaxy separation, and by one order of magnitude from z=0 to z=2. The intrinsic alignment strength also depends strongly on halo mass, but not on galaxy luminosity at fixed mass, or galaxy number density in the environment. We identify models that are in good agreement with all observational data, except that all models over-predict alignments of faint early-type galaxies. The best model yields an intrinsic alignment contamination of a Euclid-like survey between 0.5-10% at z>0.6 and on angular scales larger than a few arcminutes. Cutting 20% of red foreground galaxies using observer-frame colours can suppress this contamination by up to a factor of two.Comment: 23 pages, 14 figures; minor changes to match version published in MNRA

CORRELATIONS AMONG GRAIN CHARACTERISTICS USED TO DETERMINE THE EFFECTS OF MILLED RICE STORAGE TIME AND TEMPERATURE ON AROMATIC RICE QUALITY

Summary statistics and corresponding Spearman correlation coefficients are illustrated for various subsets of aromatic milled rice storage time and temperature data from (a) the College Station texture sensory panel, (b) the New Orleans aroma and flavor sensory panel, and (c) the Beaumont USDA-ARS Rice Quality Laboratory. These correlations represent the inclinations of seemingly-related measures of several attributes to "move together," acting as an indicator of their associations with or impacts on one another.Crop Production/Industries,

Intrinsic galaxy shapes and alignments I: Measuring and modelling COSMOS intrinsic galaxy ellipticities

The statistical properties of the ellipticities of galaxy images depend on how galaxies form and evolve, and therefore constrain models of galaxy morphology, which are key to the removal of the intrinsic alignment contamination of cosmological weak lensing surveys, as well as to the calibration of weak lensing shape measurements. We construct such models based on the halo properties of the Millennium Simulation and confront them with a sample of 90,000 galaxies from the COSMOS Survey, covering three decades in luminosity and redshifts out to z=2. The ellipticity measurements are corrected for effects of point spread function smearing, spurious image distortions, and measurement noise. Dividing galaxies into early, late, and irregular types, we find that early-type galaxies have up to a factor of two lower intrinsic ellipticity dispersion than late-type galaxies. None of the samples shows evidence for redshift evolution, while the ellipticity dispersion for late-type galaxies scales strongly with absolute magnitude at the bright end. The simulation-based models reproduce the main characteristics of the intrinsic ellipticity distributions although which model fares best depends on the selection criteria of the galaxy sample. We observe fewer close-to-circular late-type galaxy images in COSMOS than expected for a sample of randomly oriented circular thick disks and discuss possible explanations for this deficit.Comment: 18 pages, 8 figures; updated simulations and galaxy sample definition, more galaxy samples analysed; matches version published in MNRA

CORRELATIONS AMONG GRAIN CHARACTERISTICS USED TO DETERMINE THE EFFECTS OF ROUGH RICE STORAGE TIME AND TEMPERATURE ON AROMATIC RICE QUALITY

Summary statistics and corresponding Spearman correlation coefficients are illustrated for various subsets of aromatic rough rice storage time and temperature data from (a) the College Station texture sensory panel, (b) the New Orleans aroma and flavor sensory panel, and (c) the Beaumont USDA-ARS Rice Quality Laboratory. These correlations represent the inclinations of seemingly-related measures of several attributes to "move together," acting as an indicator of their associations with or impacts on one another.Crop Production/Industries,

Spatial, seasonal and climatic predicitve models of Rift Valley Fever disease across Africa

Understanding the emergence and subsequent spread of human infectious diseases is a critical global challenge, especially for high-impact zoonotic and vector-borne diseases. Global climate and land-use change are likely to alter host and vector distributions, but understanding the impact of these changes on the burden of infectious diseases is difficult. Here, we use a Bayesian spatial model to investigate environmental drivers of one of the most important diseases in Africa, Rift Valley fever (RVF). The model uses a hierarchical approach to determine how environmental drivers vary both spatially and seasonally, and incorporates the effects of key climatic oscillations, to produce a continental risk map of RVF in livestock (as a proxy for human RVF risk). We find RVF risk has a distinct seasonal spatial pattern influenced by climatic variation, with the majority of cases occurring in South Africa and Kenya in the first half of an El Niño year. Irrigation, rainfall and human population density were the main drivers of RVF cases, independent of seasonal, climatic or spatial variation. By accounting more subtly for the patterns in RVF data, we better determine the importance of underlying environmental drivers, and also make space- and time-sensitive predictions to better direct future surveillance resources. This article is part of the themed issue ‘One Health for a changing world: zoonoses, ecosystems and human well-being’

Dark Matter Halo Environment for Primordial Star Formation

We study the statistical properties (such as shape and spin) of high-z halos likely hosting the first (PopIII) stars with cosmological simulations including detailed gas physics. In the redshift range considered ($11 < z < 16$) the average sphericity is $= 0.3 \pm 0.1$, and for more than 90% of halos the triaxiality parameter is $T \lesssim 0.4$, showing a clear preference for oblateness over prolateness. Larger halos in the simulation tend to be both more spherical and prolate: we find $s \propto M_h^{\alpha_s}$ and $T \propto M_h^{\alpha_T}$, with $\alpha_s \approx 0.128$ and $\alpha_T= 0.276$ at z = 11. The spin distributions of dark matter and gas are considerably different at $z=16$, with the baryons rotating slower than the dark matter. At lower redshift, instead, the spin distributions of dark matter and gas track each other almost perfectly, as a consequence of a longer time interval available for momentum redistribution between the two components. The spin of both the gas and dark matter follows a lognormal distribution, with a mean value at z=16 of $=0.0184$, virtually independent of halo mass. This is in good agreement with previous studies. Using the results of two feedback models (MT1 and MT2) by McKee & Tan (2008) and mapping our halo spin distribution into a PopIII IMF, we find that at high-$z$ the IMF closely tracks the spin lognormal distribution. Depending on the feedback model, though, the distribution can be centered at $\approx 65 M_\odot$ (MT1) or $\approx 140 M_\odot$ (MT2). At later times, model MT1 evolves into a bimodal distribution with a second prominent peak located at $35-40 M_\odot$ as a result of the non-linear relation between rotation and halo mass. We conclude that the dark matter halo properties might be a key factor shaping the IMF of the first stars.Comment: 10 pages, 6 figures, accepted for publication in MNRA

Performance analysis of AlGaAs/GaAs tunnel junctions for ultra-high concentration photovoltaics

An n(++)-GaAs/p(++)-AlGaAs tunnel junction with a peak current density of 10 100Acm(-2) is developed. This device is a tunnel junction for multijunction solar cells, grown lattice-matched on standard GaAs or Ge substrates, with the highest peak current density ever reported. The voltage drop for a current density equivalent to the operation of the multijunction solar cell up to 10 000 suns is below 5 mV. Trap-assisted tunnelling is proposed to be behind this performance, which cannot be justified by simple band-to-band tunnelling. The metal-organic vapour-phase epitaxy growth conditions, which are in the limits of the transport-limited regime, and the heavy tellurium doping levels are the proposed origins of the defects enabling trap-assisted tunnelling. The hypothesis of trap-assisted tunnelling is supported by the observed annealing behaviour of the tunnel junctions, which cannot be explained in terms of dopant diffusion or passivation. For the integration of these tunnel junctions into a triple-junction solar cell, AlGaAs barrier layers are introduced to suppress the formation of parasitic junctions, but this is found to significantly degrade the performance of the tunnel junctions. However, the annealed tunnel junctions with barrier layers still exhibit a peak current density higher than 2500Acm(-2) and a voltage drop at 10 000 suns of around 20 mV, which are excellent properties for tunnel junctions and mean they can serve as low-loss interconnections in multijunction solar cells working at ultra-high concentrations

Variation in pinto seed coat darkening

Non-Peer ReviewedDarkening of the seed coat is a significant economic problem in pinto bean production. Beans that have darkened are considered old, more difficult to cook, and prices are discounted. Some varieties darken much more quickly than others and, as a result, are more often downgraded than those that retain their bright background colour. On a Pulse Canada marketing mission to Mexico in April 2002, all pinto bean buyers consistently identified the sample with the brightest background as their preference. They complained about the quality of pintos coming out of the Midwest USA and the eastern Prairies, primarily due to the darkened seed coats. We grew 10 different pinto varieties in four different environments and subjected the harvested beans to aging to determine the level of variability for seed coat darkening in the varieties. Varieties that maintain their bright background will be used in future breeding efforts to develop non-darkening pinto varieties

Flat pulses in a flat land – what’s on the horizon?

Non-Peer Reviewe