Adoption of Modern Agricultural Technologies in Urban Agriculture: A Case Study in Mekelle City-Vegetable Growers

Urban agriculture is an important strategy in supplying for every growing urban population affordable food and adding to their nutrients. Moreover, producing vegetable plays a significant role in contributing to the welfare of particularly poor urban residents. Vegetables are the main source of nutrients and their socio-economic importance is quite clear to the urban citizens. Consequently, production and productivity of vegetable in the urban areas should be improved. This improvement will solely be complete if modern agricultural technologies are utilized; among the most modern technologies fertilizer and pesticide take priority because of their contribution to soil fertility and hence output. In this study, the determinants of the likelihood of fertilizer and pesticide adoption decision, the intensity of use of fertilizer and volume of use of pesticide on vegetable production and whether or not income difference has come between the adopters and non-adopters of the growers in Mekelle city(the study area) were investigated. The heckman two-satage model, and OLS, which consists of a sample of 204 households, was used in the analysis. The study used both primary and secondary data for analysis. Probit regression model was employed to spot factors that determine adoption decision of the agricultural input chemical technologies like fertilizer and pesticide and heckman two-stage model was used to check financial gain difference between the adopters and non-adopters regarding to those technology adoptions. Additionally, the intensity of use of fertilizer and volume use of pesticide were investigated by employing the OLS (linear regression) model. Therefore, this study intends not solely to contribute one thing in filling the gap of data on urban agriculture by taking one part of urban agriculture that is technology adoption within vegetable production, but also aims to attract attention to the comparatively neglected area of urban agriculture. To this end, the study tried to spot the determinants that affected technology adoption decision and their intensity/volume of use in the city vegetable growers. It also tried to examine how technology adoption led to higher financial gain of the growers. Based on the result of this study, the factors that affect the likelihood of fertilizer, pesticide, and joint adoption, the intensity of use of fertilizer and volume of use of pesticide, and the income difference of the adopter and non-adopters were explained like age of household head, educational level of the household head, sex of the household head, household family size, farmer’s farming experience on vegetable cultivation, cost of fertilizer, farmer’s perception on fertilizer, soil fertility, closeness of farm land to homesteads, nearness of market to farm land, extension support, access to credit, farm size, sufficiency of irrigation water, off-farm activities, purpose of farming, total household income, cost of pesticide, and farmer’s attitude towards pesticide. This result has vital implication for the formulation of policies and programs targeted to promotion of chemical fertilizer and pesticide use in urban vegetable production mainly in the study area (Mekelle city) and other cities with similar ecological systems. Key words: Farm technology, adoption, intensity, heckman, Least Ordinary Square, Mekell

Hydrothermal synthesis of perovskite and pyrochlore powders of potassium tantalate

Potassium tantalate powders were hydrothermally synthesized at 100 to 200 °C in 4 to 15 M aqueous KOH solutions. A defect pyrochlore, Kta_(2)O_(5)(OH). nH2O (n ≈ 1.4), was obtained at 4 M KOH, but at 7–12 M KOH, this pyrochlore was gradually replaced by a defect perovskite as the stable phase. At 15 M KOH, there was no intermediate pyrochlore, only a defect perovskite, K_(0.85)Ta_(0.92)O_(2.43)(OH)_(0.57) 0.15H_(2)O. Synthesis at higher KOH concentrations led to greater incorporation of protons in the perovskite structures. The potassium vacancies required for charge compensation of incorporated protons could accommodate water molecules in the perovskite structure

Hydrothermal synthesis of KNbO_3 and NaNbO_3 powders

Orthorhombic KNbO_3 and NaNbO_3 powders were hydrothermally synthesized in KOH and NaOH solutions (6.7–15 M) at 150 and 200 °C. An intermediate hexaniobate species formed first before eventually converting to the perovskite phase. For synthesis in KOH solutions, the stability of the intermediate hexaniobate ion increased with decreasing KOH concentrations and temperatures. This led to significant variations in the induction periods and accounted for the large disparity in the mass of recovered powder for different processing parameters. It is also believed that protons were incorporated in the lattice of the as-synthesized KNbO_3 powders as water molecules and hydroxyl ions

Lattice thermal conductivity of self-assembled PbTe-Sb_2Te_3 composites with nanometer lamellae

In the system of PbTe and Sb_2Te_3, a metastable compound Pb_2Sb_6Te_(11) appears by solidification processing. It has been reported that this compound is decomposed into the two immiscible thermoelectric materials forming nanosized lamellar structure by heat treatments. The fraction transformed and the inter-lamellar spacing was systematically investigated. In this work, the thermal conductivities and the electrical resistivities have been measured as functions of annealing time through the transformation and the coarsening processes to clarify the effect of the fraction transformed and the inter-lamellar spacing. The thermal conductivity of Pb_2Sb_6Te_(11) is lower than that after the decomposition. The lattice part of the thermal conductivity of PbTe/Sb_2Te_3 lamellar samples decreases with decreasing inter-lamellar spacing. This is considered to be due to the coarsening of the microstructure

Inverse opal ceria–zirconia: architectural engineering for heterogeneous catalysis

The application of inverse opal structured materials is extended to the ceria–zirconia (Ce_(0.5)Zr_(0.5)O_2) system and the significance of material architecture on heterogeneous catalysis, specifically, chemical oxidation, is examined

Risk Factors of Deep Venous Thrombosis in Duplex and Colour Doppler Ultrasound at Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia

Background: Deep venous thrombosis is a major health problem with high morbidity and mortality worldwide. Thus early, correct and definitive diagnosis is crucial in assessing thromboembolic risk and initiating therapy. In this regard Patients at risk must be identified and given appropriate prophylaxis to reduce Venous Thromboembolism related morbidity and mortality.The main objective of this study was to determine common risk factors of deep venous thrombosis (DVT) and the common sites involved by DVT in ultrasound proven cases.Methods: This was a prospective cross-sectional study which included all patients who had proven deep venous thrombosis by Dopper and duplex ultrasound at Tikur Anbessa Specialized Hospital (TASH). Senior radiology residents collected the data after getting approval from consultant radiologists. Analysis was under taken by principal investigator.Results: There were a total 81 ultrasound proven cases of DVT involving the extremities during the study period out of which 34.6% were males and 65.4% females. The majority (58%) were under the age of 40 years. Malignancy was the most common identified risk factor (30.9% of the cases) followed by prolonged immobilization 19.8%, pregnancy related problems 6.2% and severe trauma 6.2% of the patients. No apparent risk factor was found in 12.3%. Swelling was noted in 93.8% of the participants in combination with other manifestations or alone; whereas pain was noted in 70.4% of the patients. The study showed 59.3% had involvement of the left lower limb only; 11.1% had involvement of both lower limbs. The upper extremities were affected in only one patient having bilateral involvement of brachiocephalic veins. According to the study 84% of the patients had combined involvement of the deep veins of the lower extremities extending from the common iliac veins to the poplitial veins. The study revealed that 28.4% of participants were found to havecombined involvement of the common femoral vein (CFV), superficial femoral vein (SFV) & poplitial vein; 22.2% had combined involvement of the CFV & SFV. Conclusion: From the study we concluded that Malignancy, prolonged immobilization, pregnancy related problems and major trauma were the most common risk factors noted for DVT and Swelling was the most common presenting manifestation. Majority of the patients had multiple site deep vein involvement extending from the common iliac to the poplitial veins.Key words: Risk, Factors, Deep, Vein, Thrombosis, Duplex,Doppler

Nanoscale alpha-structural domains in the phonon-glass thermoelectric material beta-Zn4Sb3

A study of the local atomic structure of the promising thermoelectric material beta-Zn4Sb3, using atomic pair distribution function (PDF) analysis of x-ray- and neutron-diffraction data, suggests that the material is nanostructured. The local structure of the beta phase closely resembles that of the low-temperature alpha phase. The alpha structure contains ordered zinc interstitial atoms which are not long range ordered in the beta phase. A rough estimate of the domain size from a visual inspection of the PDF is <~10 nm. It is probable that the nanoscale domains found in this study play an important role in the exceptionally low thermal conductivity of beta-Zn4Sb3

Profile blunting and flow blockage in a yield stress fluid: A molecular dynamics study

The flow of a simple glass forming system (a 80:20 binary Lennard-Jones mixture) through a planar channel is studied via molecular dynamics simulations. The flow is driven by an external body force similar to gravity. Previous studies show that the model exhibits both a static [Varnik et al. J. Chem. Phys. 120, 2788 (2004)] and a dynamic [F. Varnik and O. Henrich Phys. Rev. B 73, 174209 (2006)] yield stress in the glassy phase. \blue{These observations are corroborated by the present work, where we investigate how the presence of a yield stress may affect the system behavior in a Poiseuille-type flow geometry.} In particular, we observe a blunted velocity profile across the channel: A relatively wide region in the channel center flows with a constant velocity (zero shear rate) followed by a non linear change of the shear rate as the walls are approached. The observed velocity gradients are compared to those obtained from the knowledge of the shear stress across the channel and the flow-curves (stress versus shear rate), the latter being determined in our previous simulations of homogeneous shear flow. Furthermore, using the value of the (dynamic) yield stress known from previous simulations, we estimate the threshold body force for a complete arrest of the flow. Indeed, a blockage is observed as the imposed force falls below this threshold value. Small but finite shear rates are observed at stresses above the dynamic but below the static yield stress. We discuss the possible role of the \blue{stick-slip like motion} for this observation.Comment: 22 pages, 8 figure