Evaluation of long- and short-handled hand hoes for land preparation, developed in a participatory manner among women vegetable farmers in The Gambia

Objective

This study evaluated land preparation interventions (new short- and long-handled hoes), developed in a participatory manner with women vegetable farmers in West Africa, and identified indicators of long-term adoption of these interventions.

Methods

Subjects (n = 48) engaged in timed trials, alternating between using an intervention tool and their traditional hand hoe to till specified plots of land. Heart rates were measured and subjects reported the relative ergonomic comfort and safeness of the tool after each trial. Follow-up interviews and focus groups were held one, two, and three months after the trials.

Results

Compared to the traditional hoe, the new long-handled hoe required 22% less time (p = 0.01), while the new short hoe took 20% more time (p = 0.05) to till the standard plots in this study. Two months after the initial trials, 94% of subjects preferred the new hoes over the traditional hoe. Most subjects (75%) preferred the new short hoe over the new long hoe and thought it was faster (81%), despite measurements to the contrary.

Conclusions

While the new long-handled hoe performed better in the timed trials in this study, most subjects preferred the new short-handled hoe. Subjects should be sensitized on the benefits of the long-handled hoe.     

Probing the molecular basis of allergy. three-dimensional structure of the bovine lipocalin allergen Bos d 2

The three-dimensional structure of the major bovine allergen Bos d 2 has been determined by using x-ray diffraction at 1.8-A resolution. Structurally Bos d 2 is a member of the lipocalin family comprising proteins with transport functions. There is a flat small cavity inside the Bos d 2 protein core suitable for ligand binding, and it is possible that Glu115 and Asn37 inside the core are able to make hydrogen bonds with the ligand. Many allergens from different animals belong to the lipocalin family. The amino acid residue similarities between these lipocalins indicate putative regions for IgE binding. Comparison with the available allergen structures from other sources suggests that these allergens are roughly the same size and that their shape is more spherical than elliptical.     

Analysis of correlation and total power radiometer front-ends using noise waves

A complete and systematic noise analysis of radiometer front-ends, including both total power and correlation measurements, is presented. The procedure uses the concepts of noise waves and S-parameters, widely used in microwave systems design and takes into account full noise characterization of receivers including mismatch effects. The general formulation is compatible with known total power radiometer analysis and is specially appropriate in correlation radiometers for which the effect of nonideal components, such as input isolators, is analyzed. Along with numerical simulations, simple formulas are given to compute the measured visibility in nonideal conditions. The analysis is validated using experimental results consisting of correlation measurements of four receivers placed inside an anechoic chamber. Good agreement between theoretical predictions and experimental data is observed.     

The effect of crown shape on the reflectance of coniferous stands

The Kuusk-Nilson forest reflectance model was used to study the effect of crown shape on the reflectance of Scots pine and Norway spruce stands. In the first part of the study, we examined spruce and pine stands with an age range of 20-100 years and compared their simulated hemispherical-directional reflectance factors (HDRFs) at nadir in red (661 nm), NIR (838 nm) and MIR (1677 nm) when crowns were modeled as ellipsoids or cones. In all the cases, when a stand was modeled with conical crowns, it had a smaller reflectance factor than the same stand with ellipsoidal crowns.To analyze the sensitivity of HDRF on crown shape, in the second part of the study we simulated the angular distributions of HDRF of two pine stands with different leaf area index (LAI) and canopy closure values at 661 nm assuming four different crown shapes (cone, cylinder, ellipsoid, and cylinder bottom, cone top) and separated the components forming the HDRF. Considerable difference in the HDRF between the four crown shapes was observed: The larger the crown volume, the higher the canopy reflectance at similar LAI and canopy closure. A comparison of the two stands revealed that in denser stands (with a higher canopy closure) single scattering from tree crowns was responsible for the difference in HDRF between the different crown shapes, whereas in stands with a smaller canopy closure the single scattering from ground dominated the HDRF. Finally, the role of crown shape for the retrieval of LAI by inversion from remotely sensed data is discussed.     

Canopy spectral invariants for remote sensing and model applications

The concept of canopy spectral invariants expresses the observation that simple algebraic combinations of leaf and canopy spectral transmittance and reflectance become wavelength independent and determine a small set of canopy structure specific variables. This set includes the canopy interceptance, the recollision and the escape probabilities. These variables specify an accurate relationship between the spectral response of a vegetation canopy to the incident solar radiation at the leaf and the canopy scale and allow for a simple and accurate parameterization for the partitioning of the incoming radiation into canopy transmission, reflection and absorption at any wavelength in the solar spectrum. This paper presents a solid theoretical basis for spectral invariant relationships reported in literature with an emphasis on their accuracies in describing the shortwave radiative properties of the three-dimensional vegetation canopies. The analysis of data on leaf and canopy spectral transmittance and reflectance collected during the international field campaign in Flakaliden, Sweden, June 25-July 4, 2002 supports the proposed theory. The results presented here are essential to both modeling and remote sensing communities because they allow the separation of the structural and radiometric components of the measured/modeled signal. The canopy spectral invariants offer a simple and accurate parameterization for the shortwave radiation block in many global models of climate, hydrology, biogeochemistry, and ecology. In remote sensing applications, the information content of hyperspectral data can be fully exploited if the wavelength-independent variables can be retrieved, for they can be more directly related to structural characteristics of the three-dimensional vegetation canopy.     

Mapping LAI in a Norway spruce forest using airborne laser scanning

In this study we demonstrate how airborne laser scanning (ALS) can be applied to map effective leaf area index (LAI_e) in a spruce forest, after being calibrated with ground based measurements. In 2003 and 2005, ALS data and field estimates of LAI_e were acquired in a Norway spruce forest in SE Norway. We used LI-COR's LAI-2000® Plant canopy analyzer (“LAI-2000”) and hemispherical images (“HI”) for field based estimates of LAI_e. ALS penetration rate calculated from first echoes and from first and last echoes was strongly related to field estimates of LAI_e. We fitted regression models of LAI_e against the log-transformed inverse of the ALS penetration rate, and in accordance with the Beer-Lambert law this produced a linear, no-intercept relationship. This was particularly the case for the LAI-2000, having R² values > 0.9. The strongest relationship was obtained by selecting ALS data from within a circle around each plot with a radius of 0.75 times the tree height. We found a slight difference in the relationship for the two years, which can be attributed to the differences in the ALS acquisition settings. The relationship was valid across four age classes of trees representing different stages of stand development, except in one case with newly regenerated stands which most likely was an artifact. Using LAI_e based on HI data produced weaker relationships with the ALS data. This was the case even when we simulated LAI-2000 measurements based on the HI data.     

Digital Television for Mobile Devices

A survey of mobile television technologies analyzes technical characteristics for each mobile TV solution, discusses specifications and standards, and presents possible future developments.     

Gold–palladium supported on porous steel fiber matrix: Structured catalyst for benzyl alcohol oxidation and benzyl amine oxidation

Au, Pd and Au-Pd alloy are deposited on porous steel fiber matrices via sputtering technique. By this technique the preparation of the heterogeneous catalysts is clean, simple and fast as noble metal complexes, solvents or reducing agents are not needed. The studied Au-Pd catalyst exhibits good activity in the aerobic oxidation of benzyl alcohol and benzyl amines. Especially in the oxidation of benzyl amines, the Au-Pd catalyst shows a great synergistic enhancement in the activity.     

Deactivation of ZSM-5 additives in laboratory for realistic testing

ZSM-5 deactivates differently from Y zeolite. Dealumination of Y zeolite during deactivation causes UCS shrinkage and thereby decline in activity and changes in selectivity. For ZSM-5 instead deactivation removes alumina from the zeolite structure, but in spite of that the zeolite structure does not collapse. Therefore, deactivation causes activity decline due to loss of active alumina sites, but no significant changes in the strength and separation between acid sites. Unlike with FCC catalyst, physical properties of ZSM-5 additive do not change significantly with deactivation and surface area and pore volume measurements cannot be used as indications of additive performance. Yet, since both Y and ZSM-5 are used simultaneously in practice, the information on the relative rates of deactivation between the two zeolites is very important. Therefore, the question remains, what is the best way to deactivate and test ZSM-5 additives in the laboratory to obtain realistic performance, e.g. propylene yield and to obtain proper ranking of various additives. This paper discusses the effect of deactivation conditions as well as performance testing aspects of ZSM-5 additives. It is shown that choice of deactivation conditions has an effect on additive ranking and performance. By choosing the deactivation conditions properly ranking can be made clearer and more realistic additive performance is obtained.