7,695 research outputs found
Producers and Consumer attitudes toward Biotechnology in Ghana
Over 265 million people in Sub-Saharan Africa face malnutrition, chronic hunger, and poverty. One of the technologies that could help alleviate the perpetuating cycle of chronic hunger is biotechnology. Genetic modification (GM) has the potential to enhance agricultural productivity and improve Africa’s food security, but little is known about the potential benefits and costs of using genetically modified maize in Africa - Ghana. African and Ghanaian policy makers, farmers, and consumers often have difficulty accepting new technologies. Their reluctance is due to the investment required for new technology, - aversion to risk, the changes required to traditional production practices, and incomplete- knowledge of new technologies. This study elicits the knowledge, views, acceptability, preference, adaptability, and willingness-to-pay for genetically modified GM corn (maize). A survey instrument was used in two corn growing areas in the Ashanti Region of Ghana, to identify the barriers to the adoption of GM corn. The results of the study suggest that maize growers in the Ashanti region are willing to try GM maize, contrary to the current government restrictions.Producers and Consumer attitudes toward Biotechnology in Ghana, Agricultural and Food Policy, International Development, International Relations/Trade,
A Brief History of the Ohio Geological Survey
Author Institution: Ohio Division of Geological Survey, Fountain SquareSince its inception in 1837, the Ohio Geological Survey has been the principal source of geologic information in and about Ohio. These data, gathered during a 141-year period under the direction of ten state geologists, constitute more than 30,000 printed pages and numerous maps describing and illustrating Ohio's geology and mineral resources. This information has, perhaps more than any other factor, been responsible for the development within the state of important industries that rely upon mineral commodities derived from Ohio's bedrock and glacial sediments. The Ohio Division of Geological Survey is the oldest natural resources agency in the state. During the 19th century the Survey was responsible for investigation of the flora, fauna, soils, and agriculture of Ohio in addition to the primary function of geologic studies. Investigative activities of the Survey were sporadic in the 19th century; major periods of activity were 1837-1838, 1869-1874, and 1882-1893. Since 1900 the Survey has been maintained on a continuous basis, although funding and staff size have remained characteristically modest. In 1949 the Ohio Geological Survey became one of the seven originally chartered divisions of the Ohio Department of Natural Resources
Radar signal categorization using a neural network
Neural networks were used to analyze a complex simulated radar environment which contains noisy radar pulses generated by many different emitters. The neural network used is an energy minimizing network (the BSB model) which forms energy minima - attractors in the network dynamical system - based on learned input data. The system first determines how many emitters are present (the deinterleaving problem). Pulses from individual simulated emitters give rise to separate stable attractors in the network. Once individual emitters are characterized, it is possible to make tentative identifications of them based on their observed parameters. As a test of this idea, a neural network was used to form a small data base that potentially could make emitter identifications
Highly Ionized High-Velocity Clouds toward PKS 2155-304 and Markarian 509
To gain insight into four highly ionized high-velocity clouds (HVCs)
discovered by Sembach et al. (1999), we have analyzed data from the Hubble
Space Telescope (HST) and Far Ultraviolet Spectroscopic Explorer (FUSE) for the
PKS 2155-304 and Mrk 509 sight lines. We measure strong absorption in OVI and
column densities of multiple ionization stages of silicon (SiII/III/IV) and
carbon (CII/III/IV). We interpret this ionization pattern as a multiphase
medium that contains both collisionally ionized and photoionized gas. Toward
PKS 2155-304, for HVCs at -140 and -270 km/s, respectively, we measure
logN(OVI)=13.80+/-0.03 and log N(OVI)=13.56+/-0.06; from Lyman series
absorption, we find log N(HI)=16.37^(+0.22)_(-0.14) and 15.23^(+0.38)_(-0.22).
The presence of high-velocity OVI spread over a broad (100 km/s) profile,
together with large amounts of low-ionization species, is difficult to
reconcile with the low densities, n=5x10^(-6) cm^(-3), in the
collisional/photoionization models of Nicastro et al. (2002), although the HVCs
show a similar relation in N(SiIV)/N(CIV) versus N(CII)/N(CIV) as high-z
intergalactic clouds. Our results suggest that the high-velocity OVI in these
absorbers do not necessarily trace the WHIM, but instead may trace HVCs with
low total hydrogen column density. We propose that the broad high-velocity OVI
absorption arises from shock ionization, at bowshock interfaces produced from
infalling clumps of gas with velocity shear. The similar ratios of high ions
for HVC Complex C and these highly ionized HVCs suggest a common production
mechanism in the Galactic halo.Comment: 38 pages, including 10 figures. ApJ, 10 April, 2004. Replaced with
accepted versio
The Formation and Runoff of Condensate on a Vertical Glass Surface
© 2014 ASHRAE (www.ashrae.org). Published in ASHRAE Transactions, Volume 120, Part 1. For personal use only.
Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAE's prior written permission.An experimental study of condensate formation and runoff was performed by exposing a sheet of glass, cooled at its bottom edge, to an enclosure with a controlled environment. This arrangement mimics the indoor glass surface at the bottom edge of a window when the window is exposed to a cold, outdoor environment. The air in the enclosure was maintained
at a constant dry-bulb temperature (Tdb = 22.1°C [Tdb = 71.8°F]) and constant relative humidity (RH = 30%, 35%, 40%, 45%, or 50%) during individual experiments. It
was found that the time until initial runoff, tir, decreased with increasing RH, and tir was sensitive to RH at low RH, but insen-sitive to RH at high RH. At first, condensate runoff occurred near the bottom of the glass and left one to believe that the remaining condensate was at steady state. But over a 16-hour period, it was found that the condensate runoff front, in every case, progressed upward to include the entire condensate area. The speed of the condensate runoff front increased with RH, and was less sensitive to RH at low RH. Measurement results were used to produce a summary plot showing runoff front position as a function of glass surface temperature and RH.
This chart can be used to predict tir and runoff front progression at the bottom edge of any window if the surface temperature
profile is known.Canadian Window & Door Manufacturers Associatio
Interpolation of multidimensional diabatic potential energy matrices
A method for constructing diabatic potential energy matrices by interpolation of ab initio quantum chemistry data is described and tested. This approach is applicable to any number of interacting electronic states, and relies on a formalism and a computational procedure that are more general than those presented previously for the case of two electronic states. The method is tested against an analytic model for three interacting electronic states of NH₃⁺
ARAS: an automated radioactivity aliquoting system for dispensing solutions containing positron-emitting radioisotopes.
BackgroundAutomated protocols for measuring and dispensing solutions containing radioisotopes are essential not only for providing a safe environment for radiation workers but also to ensure accuracy of dispensed radioactivity and an efficient workflow. For this purpose, we have designed ARAS, an automated radioactivity aliquoting system for dispensing solutions containing positron-emitting radioisotopes with particular focus on fluorine-18 ((18)F).MethodsThe key to the system is the combination of a radiation detector measuring radioactivity concentration, in line with a peristaltic pump dispensing known volumes.ResultsThe combined system demonstrates volume variation to be within 5 % for dispensing volumes of 20 μL or greater. When considering volumes of 20 μL or greater, the delivered radioactivity is in agreement with the requested amount as measured independently with a dose calibrator to within 2 % on average.ConclusionsThe integration of the detector and pump in an in-line system leads to a flexible and compact approach that can accurately dispense solutions containing radioactivity concentrations ranging from the high values typical of [(18)F]fluoride directly produced from a cyclotron (~0.1-1 mCi μL(-1)) to the low values typical of batches of [(18)F]fluoride-labeled radiotracers intended for preclinical mouse scans (~1-10 μCi μL(-1))
Determining Longwave Radiative Properties Of Flat Shading Materials
Solar gain through fenestration has a significant impact on building peak load and annual energy consumption. Shading devices, attached to fenestration, offer a cost effective strategy in controlling solar gain. The performance of a particular shading device is dependent on solar optical and longwave radiative properties of the device. The current study considers longwave properties of three flat shading materials; drapery fabrics, insect screens and roller blinds. Each of these materials consists of a structure (i.e., yarn, wire, sheet) that is opaque with respect to longwave (infrared) radiation and each material is likely to have some openness. Material emittance and longwave transmittance measurements were taken with an infrared reflectometer using two backing surfaces. The results show emittance and longwave transmittance to be simple functions of openness, emittance and longwave transmittance of the structure. This is especially useful because openness can be determined from solar transmittance measurements while emittance and longwave transmittance of the structure was found to be constant for each category of shading material.NSERC || ASHRA
A Simplified Method For Calculating The Effective Solar Optical Properties Of a Drapery
The use of draperies to control solar gain through windows is common in residential and commercial buildings and their potential for reduction of building peak load and annual energy consumption is recognized to be large. Thus, there is a strong need for models that allow a drapery to be included in glazing system analysis. As an approximation, the drapery is modelled as a series of uniformly arranged rectangular pleats with fabric transmitting and reflecting diffusely any incident radiation. The “effective” solar optical properties of the drapery are then determined by considering an enclosure which is representative of the entire series of pleats. The optical properties of the drapery are functions of the pleat geometry and the optical properties of the fabric. Optical properties are also influenced by the directional nature of the incident radiation. In the case of incident beam radiation, the results are presented as a function of the solar profile angle for a folding ratio corresponding to 100% fullness. The results for incident diffuse radiation on the other hand are presented in terms of fabric properties and the folding ratio of the drapery.Natural Sciences and Engineering Research Council of Canada (NSERC) Graduate Scholarship to N.A. Kotey || ASHRAE 1311-TR
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