CONSUMER PREFERENCES AS DRIVERS OF THE COMMON BEAN TRADE IN TANZANIA: A MARKETING PERSPECTIVE

The objective of this study was to determine the impact of bean grain quality characteristics on market price. The data was collected from retail markets in Tanzania. Hedonic pricing provides a statistical estimate of premiums and discounts. Implications for development of bean markets include: i) extension agents should identify cost-effective ways to educate producers on targeting urban market niches based on consumer preferences for varieties, ii) breeding for bruchid resistant beans and use of appropriate storage technologies would alleviate the problems of storage damage, and iii) requiring a portfolio of grain quality characteristics to fit consumer preferences in local markets.Beans, markets, consumer preferences, hedonic, storage, Tanzania

Osteoclastic Resorption of Calcium Phosphate Ceramic Thin Films

Sub-micron calcium phosphate ceramic thin films were formed by vertically dipping transparent quartz plates in a particulate sol-gel suspension. Primary adult rat bone marrow cell populations were cultured on the ceramic thin films in conditions known to allow the differentiation of cells of the osteoclast lineage. Monitoring the cultures for periods of 11 to 28 days revealed the creation of resorption lacunae in the thin films by multinucleate cells. Some cultures were heated at 42 °C overnight to remove adherent cells; using bright field light microscopy (LM), after staining with silver nitrate, the degree of resorption could be easily assessed. Other cultures were fixed and stained for tartrate-resistant acid phosphatase (TRAP) activity and prepared for LM and/ or scanning electron microscopy (SEM). Examination of the cultures, following fixation, showed the multinucleate cells associated with resorption lacunae to be TRAP positive. The nuclearity of the cells varied considerably. SEM showed that the cells had resorbed the thin films to produce discrete resorption lacunae similar to those found in normal bone tissue. From their morphology, TRAP positive staining, and resorptive activity, the cells were considered to be osteoclasts. The size of individual or combined lacunae varied from \u3c 10 μm to - 1 mm. These thin film culture substrata may be employed to investigate the function of individual resorbing cells or, especially after removal of the adherent cell layer, easily quantify resorption which is the major functional activity of osteoclasts. We conclude that these thin film ceramic culture substrata can be used as alternatives to bone slices in osteoclast resorption assays and thus could be employed to investigate both the functional and metabolic activities of osteoclasts

The Texas Cave Bug and the California Arroyo Toad Take on the Constitution\u27s Commerce Clause.

Abstract Forthcoming

Profitable chemical-free cowpea storage technology for smallholder farmers in Africa: opportunities and challenges

Cowpea is the most economically and nutritionally important indigenous African grain legume, grown by millions of resource-poor farmers. It is a key cash crop in areas too dry to grow cotton or other export crops. Most of the over 3 million t of cowpea grain produced annually in West and Central Africa is grown on small farms. Storage is often identified as the key challenge for small scale cowpea growers. Many farmers sell cowpea grain at low harvest time prices rather than risk losses by bruchids during storage. Some traditional methods are effective for small quantities (e.g., 10 kg), but are difficult to scale up. Some effective storage chemicals are available, but they are regularly misused by farmers and merchants. The Purdue Improved Cowpea Storage (PICS) Project is addressing these problems through promotion of hermetic storage in triple layer sacks which have an outer layer of woven polypropylene and two liners of 80 μ high-density polyethylene. Village demonstrations with more than 45, 000 PICS sacks have shown the technology to be effective. Good quality affordable sacks have been produced by manufacturers in Nigeria, Burkina Faso and Mali. Over the past three years more than one million sacks have been produced and sold. Despite the success with the outreach activities and the farmer adoption, the challenge remains to develop sustainable sack distribution networks. Issues identified include reluctance of wholesalers to order sacks due to risk associated with a new product, inability of wholesalers to develop effective distribution networks due to difficulties with enforcing contracts, and limited access to capital. The PICS project is exploring new ways to address some of these issues, including using non-traditional distribution systems for PICS sacks such as agro-dealers networks, and adapting distribution systems that have worked for cell phones and other products. Keywords: Cowpea, Bruchids, Hermetic storage, Supply chain, West and Central Afric

The Texas Cave Bug and the California Arroyo Toad Take on the Constitution\u27s Commerce Clause.

Abstract Forthcoming

CONSUMER PREFERENCES FOR QUALITY CHARACTERISTICS ALONG THE COWPEA VALUE CHAIN IN NIGERIA, GHANA AND MALI

The production and trade of cowpea (Vigna Uniculata), called “blackeyed peas” in the US, are a growing business for farmers and merchants serving the rapidly expanding urban areas of West and Central Africa. Cowpea fits the needs of the urban poor. It is an inexpensive source of protein that does not require refrigeration. A better understanding of consumer preferences for cowpea is essential to market development. The main objective of the study was to determine the cowpea grain quality characteristics that command a price premium or provoke a discount in Ghanaian, Malian and Nigerian markets. Specifically, the study looked at the impact of the grain size, texture, color, eye color, and bruchid-damaged grains on cowpea market prices. The data for the study were collected from six markets in Ghana; four markets were in the capital city of Accra and two markets in Kumasi. In Mali, two markets were surveyed, Marché de Sabalibougou and Marché Medine. In Nigeria three markets were surveyed, Iddo in Lagos; Monday, in Maiduguri; and Dawanau in Kano. Hedonic pricing methods provide a statistical estimate of premiums and discounts. The results of the study indicated that cowpea consumers in Ghana, Mali and Nigeria are willing to pay a premium for large cowpea grains. Cowpea consumers discount grains with storage damage from the very first bruchid hole. The impact of price on other cowpea quality characteristics such as skin color and texture, and eye color varies locally. Implications for development of the cowpea value chain include: 1) breeders and cowpea production researchers should identify cost-effective ways to increase cowpea grain size because larger grain size is almost universally preferred, and 2) entomologists and storage experts should develop and transfer improved storage technologies to reduce damage discounts, and 3) serving local markets requires a portfolio of grain skin color, eye color and skin texture combinations.Cowpeas market chains, consumer preference, hedonic price analysis

Deposition and Resorption of Calcified Matrix in Vitro by Rat Marrow Cells

Rat bone marrow derived cells were cultured using a-Minimal Essential Medium supplemented with antibiotics, ascorbic acid and !3-glycerphosphate in the presence of 10-8M dexamethasone, on polystyrene and hydrophilic fluorocarbon substrata for periods of 2 - 4 weeks. During this time, a large yield of bone nodules was achieved and the elaborated tissue was examined by both scanning and transmission electron microscopy. The matrix produced by the cells contacting the underlying substratum was an afibrillar, globular, calcified material which formed a layer approximately 0.5μm thick. The calcium and phosphorus content of this material was confirmed by energy dispersive X-ray dot mapping analysis. The collagenous matrix of the forming bone nodules was intimately associated with, and anchored to, this layer. The bulk of the bone nodule, above the interfacial zone, was of a normal appearance with osteocytes buried in a collagenous matrix exhibiting spheritic foci of mineralization. The cells, but not the extracellular matrix, of this culture were then removed using a trypsin citrate saline solution and the dishes containing these nodules reseeded with fresh bone marrow cells. These second stage cultures were maintained in supplemented medium, without dexamethasone. During this second period, osteoclasts resorbed both the afibrillar and collagen containing calcified matrices laid down in the first stage of the culture, producing characteristic scalloped osteoclast resorption lacunae

Mineralized Matrix Production by Osteoblasts on Solid Titanium In Vitro

Rat bone marrow cells were cultured on solid commercially pure titanium discs. Extracellular matrix (ECM) formed by the cells and the ECM/metal interface developed were examined by both scanning and transmission electron microscopy. The ECM most intimately associated with the substratum comprised afibrillar calcium phosphate globular accretions produced by the colonizing osteoblasts. The presence of calcium and phosphorus was confirmed by energy dispersive X-ray analysis. This initial layer acted as a site of anchorage for collagen fibres, produced by the osteoblasts. However, flaps of tissue elaborated during the culture period and manually reflected created a tissue division immediately above the afibrillar layer which indicated that the latter was adherent to the underlying metal oxide surface. The collagen matrix, consisting of networks of fibres, became mineralized with time in culture and also enveloped osteocytes which possessed radiating cell processes to form a bone nodule. This in vitro study suggests that while a calcified matrix layer, produced by osteoblasts, may adhere to titanium surfaces, subsequently formed bone is separated from this layer by a zone rich in both proteoglycans (as demonstrated by ruthenium red staining) and collagen fibres

Application of bifurcation methods for the prediction of low-speed aircraft ground performance

The design of aircraft for ground maneuvers is an essential part in satisfying the demanding requirements of the aircraft operators. Extensive analysis is done to ensure that a new civil aircraft type will adhere to these requirements, for which the nonlinear nature of the problem generally adds to the complexity of such calculations. Small perturbations in velocity, steering angle, or brake application may lead to significant differences in the final turn widths that can be achieved. Here, the U-turn maneuver is analyzed in detail, with a comparison between the two ways in which this maneuver is conducted. A comparison is also made between existing turn-width prediction methods that consist mainly of geometric methods and simulations and a proposed new method that uses dynamical systems theory. Some assumptions are made with regard to the transient behavior, for which it is shown that these assumptions are conservative when an upper bound is chosen for the transient distance. Furthermore, we demonstrate that the results from the dynamical systems analysis are sufficiently close to the results from simulations to be used as a valuable design tool. Overall, dynamical systems methods provide an order-of-magnitude increase in analysis speed and capability for the prediction of turn widths on the ground when compared with simulations. Nomenclature co = oleo damping coefficient, N s2 =m2 cz = tire vertical damping coefficient Fco = damping force in oleo due to the orifice,