Constraints to the sustainability of a ‘systematised’ approach to livestock marketing amongst smallholder cattle producers in South Africa

Commercialization of smallholder agriculture in South Africa is underpinned by reforms to improve livestock off-take in communal areas and engage smallholder farmers with formal markets. To achieve this, Custom Feeding Programmes (CFPs) were established to improve the condition of communal cattle prior to their sale into formal markets and to ‘systematise’ the informal marketing of cattle in communal areas by enabling participants to achieve higher informal market prices. We evaluate the sustainability of eight CFPs located in Eastern Cape Province in terms of their ability to add value to smallholder cattle production and encourage market participation. Communities with CFPs achieved a 16.6% mean cattle off-take rate, substantially higher than in most communal systems. Furthermore, cattle sold through CFPs attained a 17% higher mean selling price than those sold through other marketing channels. However, these benefits were mainly realized by better-off farmers with larger cattle herds and greater ability to transport animals to and from CFPs. More marginalized farmers, particularly women, had low participation. CFPs also face challenges to their sustainability, including inconsistent feed and water supplies, poor infrastructure and high staff turnover. Key to enhancing participation in CFPs, will be improving the way they are supported and embedded within communities

Asynchronous Corner Tracking Algorithm based on Lifetime of Events for DAVIS Cameras

Event cameras, i.e., the Dynamic and Active-pixel Vision Sensor (DAVIS) ones, capture the intensity changes in the scene and generates a stream of events in an asynchronous fashion. The output rate of such cameras can reach up to 10 million events per second in high dynamic environments. DAVIS cameras use novel vision sensors that mimic human eyes. Their attractive attributes, such as high output rate, High Dynamic Range (HDR), and high pixel bandwidth, make them an ideal solution for applications that require high-frequency tracking. Moreover, applications that operate in challenging lighting scenarios can exploit the high HDR of event cameras, i.e., 140 dB compared to 60 dB of traditional cameras. In this paper, a novel asynchronous corner tracking method is proposed that uses both events and intensity images captured by a DAVIS camera. The Harris algorithm is used to extract features, i.e., frame-corners from keyframes, i.e., intensity images. Afterward, a matching algorithm is used to extract event-corners from the stream of events. Events are solely used to perform asynchronous tracking until the next keyframe is captured. Neighboring events, within a window size of 5x5 pixels around the event-corner, are used to calculate the velocity and direction of extracted event-corners by fitting the 2D planar using a randomized Hough transform algorithm. Experimental evaluation showed that our approach is able to update the location of the extracted corners up to 100 times during the blind time of traditional cameras, i.e., between two consecutive intensity images.Comment: Accepted to 15th International Symposium on Visual Computing (ISVC2020

An Empirical Model for Estimating Annual Consumption by Freshwater Fish Populations

Population consumption is an important process linking predator populations to their prey resources. Simple tools are needed to enable fisheries managers to estimate population consumption. We assembled 74 individual estimates of annual consumption by freshwater fish populations and their mean annual population size, 41 of which also included estimates of mean annual biomass. The data set included 14 freshwater fish species from 10 different bodies of water. From this data set we developed two simple linear regression models predicting annual population consumption. Log-transformed population size explained 94% of the variation in log-transformed annual population consumption. Log-transformed biomass explained 98% of the variation in log-transformed annual population consumption. We quantified the accuracy of our regressions and three alternative consumption models as the mean percent difference from observed (bioenergetics-derived) estimates in a test data set. Predictions from our population-size regression matched observed consumption estimates poorly (mean percent difference = 222%). Predictions from our biomass regression matched observed consumption reasonably well (mean percent difference = 24%). The biomass regression was superior to an alternative model, similar in complexity, and comparable to two alternative models that were more complex and difficult to apply. Our biomass regression model, log10(consumption) = 0.5442 + 0.9962 · log10(biomass), will be a useful tool for fishery managers, enabling them to make reasonably accurate annual population consumption predictions from mean annual biomass estimates

Sampling Effort and Uncertainty in Leaf Litterfall Mass and Nutrient Flux in Northern Hardwood Forests

Designs for litterfall sampling can be improved by understanding the sources of uncertainty in litterfall mass and nutrient concentration. We compared the coefficient of variation of leaf litterfall mass and nutrient concentrations (nitrogen, phosphorus, calcium, magnesium, and potassium) at different spatial scales and across years for six northern hardwood species from 23 stands in the White Mountains of New Hampshire, USA. Stands with steeper slopes (P = 0.01), higher elevations (P = 0.05), and more westerly aspect (P = 0.002) had higher interannual variation in litter mass, probably due to a litter trap design that allowed litter to blow into traps in windy years. The spatial variation of nutrient concentrations varied more across stands than within stands for all elements (P \u3c 0.001). Phosphorus was the most spatially variable of all nutrients across stands (P \u3c 0.001). Litter nutrient concentrations varied less from year to year than litter mass, but the magnitude of difference depended on the element and tree species. We compared the relative importance of variation in mass vs. concentration to estimates of nutrient flux by simulating different sampling intensities of one while holding the other constant. In this dataset, interannual variability of leaf litter mass contributed more to uncertainty in litterfall flux calculations than interannual variation in nutrient concentrations. Optimal sampling schemes will depend on the elements of interest and local factors affecting spatial and temporal variability

Diversity of Arbuscular Mycorrhizal Fungi in the Rhizosphere of Solaris and Regent Grapevine Plants Treated with Bioproducts

The aim of this study was to identify the spores of arbuscular mycorrhizal fungi (AMF) in the rhizosphere of Solaris and Regent grapevine plants grafted onto SO4 rootstock and treated with bioproducts. The bioproducts Ausuma, Bioilsa, manure and BF Ekomix were tested and applied on their own, or combined with standard mineral fertilisation (NPK). The applied bioproducts contributed to an increase in the number of species of mycorrhizal fungi in the rhizosphere soil of the grapevines. The most frequently occurring AMF species was Claroideoglomus claroideum. Biopreparation BF Ekomix was a promisingagent for increasing the number of AMF spores in the rhizosphere of Regent grapevines. In the rhizosphere of Solaris, a positive influence on the number of spores occurred after the application of Bioilsa

A coarsened multinomial regression model for perinatal mother to child transmission of HIV

Background: In trials designed to estimate rates of perinatal mother to child transmission of HIV, HIV assays are scheduled at multiple points in time. Still, infection status for some infants at some time points may be unknown, particularly when interim analyses are conducted. Methods: Logistic regression models are commonly used to estimate covariate-adjusted transmission rates, but their methods for handling missing data may be inadequate. Here we propose using coarsened multinomial regression models to estimate cumulative and conditional rates of HIV transmission. Through simulation, we compare the proposed models to standard logistic models in terms of bias, mean squared error, coverage probability, and power. We consider a range of treatment effect and visit process scenarios, while including imperfect sensitivity of the assay and contamination of the endpoint due to early breastfeeding transmission. We illustrate the approach through analysis of data from a clinical trial designed to prevent perinatal transmission. Results: The proposed cumulative and conditional models performed well when compared to their logistic counterparts. Performance of the proposed cumulative model was particularly strong under scenarios where treatment was assumed to increase the risk of in utero transmission but decrease the risk of intrapartum and overall perinatal transmission and under scenarios designed to represent interim analyses. Power to estimate intrapartum and perinatal transmission was consistently higher for the proposed models. Conclusion: Coarsened multinomial regression models are preferred to standard logistic models for estimation of perinatal mother to child transmission of HIV, particularly when assays are missing or occur off-schedule for some infants.U.S. National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), and Dept. of Health and Human Services (DHHS)

Biodistribution PET/CT study of hemoglobin-DFO-89Zr complex in healthy and lung tumor-bearing mice

Proteins, as a major component of organisms, are considered the preferred biomaterials for drug delivery vehicles. Hemoglobin (Hb) has been recently rediscovered as a potential drug carrier, but its use for biomedical applications still lacks extensive investigation. To further explore the possibility of utilizing Hb as a potential tumor targeting drug carrier, we examined and compared the biodistribution of Hb in healthy and lung tumor-bearing mice, using for the first time89 Zr labelled Hb in a positron emission tomography (PET) measurement. Hb displays a very high conjugation yield in its fast and selective reaction with the maleimide-deferoxamine (DFO) bifunctional chelator. The high-resolution X-ray structure of the Hb-DFO complex demonstrated that cysteine β93 is the sole attachment moiety to the αβ-protomer of Hb. The Hb-DFO complex shows quantitative uptake of89 Zr in solution as determined by radiochromatography. Injection of 0.03 mg of Hb-DFO-89 Zr complex in healthy mice indicates very high radioactivity in liver, followed by spleen and lungs, whereas a threefold increased dosage results in intensification of PET signal in kidneys and decreased signal in liver and spleen. No difference in biodistribution pattern is observed between naïve and tumor-bearing mice. Interestingly, the liver Hb uptake did not decrease upon clodronate-mediated macrophage depletion, indicating that other immune cells contribute to Hb clearance. This finding is of particular interest for rapidly developing clinical immunology and projects aiming to target, label or specifically deliver agents to immune cells

Gregariousness Does Not Vary with Geography, Developmental Stage, or Group Relatedness in Feeding Redheaded Pine Sawfly Larvae

Aggregations are widespread across the animal kingdom, yet the underlying proximate and ultimate causes are still largely unknown. An ideal system to investigate this simple, social behavior is the pine sawfly genus Neodiprion, which is experimentally tractable and exhibits interspecific variation in larval gregariousness. To assess intraspecific variation in this trait, we characterized aggregative tendency within a single widespread species, the redheaded pine sawfly (N. lecontei). To do so, we developed a quantitative assay in which we measured interindividual distances over a 90-min video. This assay revealed minimal behavioral differences: (1) between early-feeding and late-feeding larval instars, (2) among larvae derived from different latitudes, and (3) between groups composed of kin and those composed of nonkin. Together, these results suggest that, during the larval feeding period, the benefits individuals derive from aggregating outweigh the costs and that this cost-to-benefit ratio does not vary dramatically across space (geography) or ontogeny (developmental stage). In contrast to the feeding larvae, our assay revealed a striking reduction in gregariousness following the final larval molt in N. lecontei. We also found some intriguing interspecific variation: While N. lecontei and N. maurus feeding larvae exhibit significant aggregative tendencies, feeding N. compar larvae do not aggregate at all. These results set the stage for future work investigating the proximate and ultimate mechanisms underlying developmental and interspecific variation in larval gregariousness across Neodiprion

The stress hormone corticosterone in a marine top predatorreflects short-term changes in food availability

-In many seabird studies, single annual proxies of prey abundance have been used to explain variability in breeding performance, but much more important is probably the timing of prey availability relative to the breeding season when energy demand is at a maximum. Until now, intraseasonal variation in prey availability has been difficult to quantify in seabirds. Using a state-of-the-art ocean drift model of larval cod Gadus morhua, an important constituent of the diet of common guillemots Uria aalge in the southwestern Barents Sea, we were able to show clear, short-term correlations between food availability and measurements of the stress hormone corticosterone (CORT) in parental guillemots over a 3-year period (2009–2011). The model allowed the extraction of abundance and size of cod larvae with very high spatial (4 km) and temporal resolutions (1 day) and showed that cod larvae from adjacent northern spawning grounds in Norway were always available near the guillemot breeding colony while those from more distant southerly spawning grounds were less frequent, but larger. The latter arrived in waves whose magnitude and timing, and thus overlap with the guillemot breeding season, varied between years. CORT levels in adult guillemots were lower in birds caught after a week with high frequencies of southern cod larvae. This pattern was restricted to the two years (2009 and 2010) in which southern larvae arrived before the end of the guillemot breeding season. Any such pattern was masked in 2011 by already exceptionally high numbers of cod larvae in the region throughout chick-rearing period. The findings suggest that CORT levels in breeding birds increase when the arrival of southern sizable larvae does not match the period of peak energy requirements during breeding. Common guillemot, CORT, food availability, seabird, Uria aalg

Susceptibility of Eggs and Adult Fecundity of the Lesser Grain Borer, Rhyzopertha dominca, Exposed to Methoprene

A series of tests were conducted to determine the susceptibility of eggs and neonates of the lesser grain borer Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae = Bostrychidae), exposed to the insect growth regulator, methoprene, on filter paper and on rough rice. In the first test, the hatch rate of eggs exposed on filter paper treated with methoprene at the label rate of 0.003 mg [AI]/cm2 when used as a surface treatment in structures was 52.0 ± 7.3% compared to 93.0 ± 3.3% on untreated controls. In the second test, eggs were exposed to a dose-response series of 0.00003 to 0.03 mg[AI]/cm2. Egg hatch was directly proportional to concentration and ranged from 85.0 ± 2.0% on untreated controls to 26.7 ± 8.3% at the highest concentration tested. In the third test, 1 ppm of methoprene was sprayed on long grain rough rice (paddy) (Cocodrie variety), and then individual kernels were cracked and an egg of R. dominica was placed directly on the kernel. On untreated rice kernels, 67.5 ± 11.6% of the eggs hatched and were able to bore inside, and all of these larvae emerged as adults. In contrast, 40.0 ± 5.3% of the eggs placed on treated cracked kernels were able to develop to where the larvae were visible through X-ray detection, but none emerged as adults. In the final test, newly-emerged adults were exposed on rough rice treated with 1 ppm methoprene. The number of eggs from adults on untreated rice was 52.1 ± 4.3 eggs per female, and on treated rice the average egg production was 12.5 ± 1.1 eggs per female. Methoprene applied on a surface or on rough rice affected development of egg hatch also reduced fecundity of parent adults exposed on the treated rough rice