Search

The economic return for peanut (Arachis hypogaea L.) in Ghana is often low due to limitations in the availability of inputs or their adoption, which are needed to optimize yield. Six experiments were conducted in Ghana in 2020 and 2021 to determine the impact of planting date, cultivar, fertilization, pest management practices, and harvest date on peanut yield, financial return, and pest reaction. A wide range of interactions among these treatment factors were often observed for infestations of aphids (Aphis gossypii Glover); groundnut rosette disease (Umbravirus: Tombusviridaee); millipedes (Peridontopyge spp.); white grubs (Schyzonicha spp.); wireworms (Conoderus spp.); termites (Microtermes and Odontotermes spp.); canopy defoliation as a result of early leaf spot disease caused by Passalora arachidicola (Hori) and late leaf spot caused by Nothopassalora personata (Berk. and M. A. Curtis); and the scarification and boring of pods caused by arthropod feeding. Pod yield and economic return increased for the cultivar Chitaochi and Sarinut 2 when fertilizer was applied and when fertilizer was applied at early, mid-, and late planting dates. Pod yield and economic return increased when a combination of locally derived potassium soaps was used for aphid suppression and one additional hand weeding was used in the improved pest management practice compared with the traditional practice without these inputs. Pearson correlations for yield and economic return were negatively correlated for all pests and damage caused by pests. The results from these experiments can be used by farmers and their advisors to develop production packages for peanut production in Ghana. [ABSTRACT FROM AUTHOR]

SiC vertical MOSFETs are fabricated and characterized with blocking voltages of about 1 kV and a specific on-resistance as low as 8.3 m[omega].[cm.sup.2]. The internal body diode's reverse recovery characteristics have shown injection-limited conduction, which are attributed to the implanted P-anode layers.

The performance of bias stress induced breakdown voltage (BV) slump measurements on DMOSFETs is discussed. Findings reveal that the BV slumped after the DMOSFET was bias stressed at 1200 V for 2 hours at 175 degree Celsius.

Invasive alien species (IAS) continue to shape the global landscape through their effects on biological diversity and agricultural productivity. The effects are particularly pronounced in Sub-Saharan Africa, which has seen the arrival of many IAS in recent years. This has been attributed to porous borders, weak cross border biosecurity, and inadequate capacity to limit or stop invasions. Prediction and early detection of IAS, as well as mechanisms of containment and eradication, are needed in the fight against this global threat. Horizon scanning is an approach that enables gathering of information on risk and impact that can support IAS management. A study was conducted in Ghana to establish two ranked lists of potential invasive alien plant pest species that could be harmful to agriculture, forestry, and the environment, and to rank them according to their potential threat. The ultimate objective was to enable prioritization of actions including pest risk analysis, prevention, surveillance and contingency plans. Prioritisation was carried out using an adapted version of horizon scanning and consensus methods developed for ranking IAS worldwide. Following a horizon scan of invasive alien species not yet officially present in Ghana, a total of 110 arthropod and 64 pathogenic species were assessed through a simplified pest risk assessment. Sixteen species, of which 14 were arthropods and two pathogens, had not been recorded on the African continent at the time of assessment. The species recorded in Africa included 19 arthropod and 46 pathogenic species which were already recorded in the neighbouring countries of Burkina Faso, Côte d'Ivoire, and Togo. The majority of arthropod species were likely to arrive as contaminants on commodities, followed by a sizable number which were likely to arrive as stowaways, while some species were capable of long distance dispersal unaided. The main actions suggested for species that scored highly included full pest risk analyses and, for species recorded in neighbouring countries, surveys to determine their presence in Ghana were recommended. [ABSTRACT FROM AUTHOR]

Suppressing pest populations below economically-damaging levels is an important element of sustainable peanut (Arachis hypogaea L.) production. Peanut farmers and their advisors often approach pest management with similar goals regardless of where they are located. Anticipating pest outbreaks using field history and monitoring pest populations are fundamental to protecting yield and financial investment. Microsoft Excel was used to develop individual risk indices for pests, a composite assessment of risk, and costs of risk mitigation practices for peanut in Argentina, Ghana, India, Malawi, and North Carolina (NC) in the United States (US). Depending on pests and resources available to manage pests, risk tools vary considerably, especially in the context of other crops that are grown in sequence with peanut, cultivars, and chemical inputs. In Argentina, India, and the US where more tools (e.g. mechanization and pesticides) are available, risk indices for a wide array of economically important pests were developed with the assumption that reducing risk to those pests likely will impact peanut yield in a positive manner. In Ghana and Malawi where fewer management tools are available, risks to yield and aflatoxin contamination are presented without risk indices for individual pests. The Microsoft Excel platform can be updated as new and additional information on effectiveness of management practices becomes apparent. Tools can be developed using this platform that are appropriate for their geography, environment, cropping systems, and pest complexes and management inputs that are available. In this article we present examples for the risk tool for each country. [ABSTRACT FROM AUTHOR]

Annual variation in phenology can have profound effects on the behavior of animals. As climate change advances spring phenology in ecosystems around the globe, it is becoming increasingly important to understand how animals respond to variation in the timing of seasonal events and how their responses may shift in the future. We investigated the influence of spring phenology on the behavior of migratory, barren‐ground caribou (Rangifer tarandus), a species that has evolved to cope with short Arctic summers. Specifically, we examined the effect of spring snow melt and vegetation growth on the current and potential future space‐use patterns of the Porcupine Caribou Herd (PCH), which exhibits large, inter‐annual shifts in their calving and post‐calving distributions across the U.S.–Canadian border. We quantified PCH selection for snow melt and vegetation phenology using machine learning models, determined how selection resulted in annual shifts in space‐use, and then projected future distributions based on climate‐driven phenology models. Caribou exhibited strong, scale‐dependent selection for both snow melt and vegetation growth. During the calving season, caribou selected areas at finer scales where the snow had melted and vegetation was greening, but within broader landscapes that were still brown or snow covered. During the post‐calving season, they selected vegetation with intermediate biomass expected to have high forage quality. Annual variation in spring phenology predicted major shifts in PCH space‐use. In years with early spring phenology, PCH predominately used habitat in Alaska, while in years with late phenology, they spent more time in Yukon. Future climate conditions were projected to advance spring phenology, shifting PCH calving and post‐calving distributions further west into Alaska. Our results demonstrate that caribou selection for habitat in specific phenological stages drive dramatic shifts in annual space‐use patterns, and will likely affect future distributions, underscoring the importance of maintaining sufficient suitable habitat to allow for behavioral plasticity. [ABSTRACT FROM AUTHOR]

Presently, high-power soft-switching resonant pole converters, such as the auxiliary resonant commutated pole (ARCP) converter, that have internal dc link voltages above 1.5 kV, can only use gate turn-off thyristors (GTO's) as main switching devices. For these applications, considerable effort has been spent to design, evaluate, and enhance the dynamic performance of high-voltage MOS-controlled thyristors (HVMCT's). It is expected that in the near future HVMCT's, which require little gate power because of their high gate impedance, will gradually replace high-voltage GTO's. The purpose of this paper is to present and summarize key HVMCT characterization results gathered to date as they relate to their dynamic performance during zero-voltage switching. HVMCT devices capable of turning off 300 A and withstanding 3000 V are presented. The paper concludes with a comparison of the soft-switching performance of HVMCT's and GTO's in an ARCP converter phase leg.

Richard Hooker is said to have invented Anglicanism in his Of the Laws of Ecclesiastical Polity, giving character to an Elizabethan “settlement” of religion sadly lacking it. The Laws is a model of creative response to deeply alarming civil and religious circumstances. It is the major prose work of the English sixteenth century and is important in other ways. Hooker’s distinctive sense of law and rich sense of reason are explored here as major elements in his work. The aim is to suggest the enduring interest of the Laws as a whole by pursuing two of its important themes. Of particular current interest is the framework Hooker offers for understanding the sometimes violent entanglements of religion and politics. [ABSTRACT FROM AUTHOR]

The muskox ( Ovibos moschatus) population inhabiting the eastern North Slope (ENS) of Alaska, US declined dramatically during 1999-2006, whereas populations in western Alaska (WA) were stable or increasing. To understand morbidity and mortality factors contributing to the decline, Alaska Department of Fish and Game conducted pathologic investigations of carcasses from 2005 until 2008. Additionally, archived sera from both ENS and WA muskoxen collected during 1984-92, before the documented beginning of the ENS decline; sera collected during 2000, near the beginning of the decline; and contemporary sera (from live capture-release, adult females) collected during 2006, 2007, and 2008 were analyzed to determine whether prevalence of antibody to potential pathogens differed in the two areas or changed over time. The pathogens investigated were those that were believed could cause lameness or poor reproduction or adversely affect general health. Furthermore, trace mineral levels, hemograms, and gastrointestinal parasites were evaluated in live adult females captured 2006-08. Pathologic investigations identified several comorbid conditions, including predation, polyarthritis caused by or consistent with Chlamydophila spp. infection, hoof lesions, copper deficiency, contagious ecthyma, verminous pneumonia, hepatic lipidosis suggestive of negative energy balance, and bacterial bronchopneumonia due to Trueperella pyogenes and Bibersteinia trehalosi. Pathogens suspected to be newly introduced in the ENS muskox population on the basis of serologic detection include bovine viral diarrhea, respiratory syncytial virus, Chlamydophila spp., Brucella spp., Coxiella burnetii, and Leptospira spp., whereas parainfluenza virus-3 antibody prevalence has increased in the WA population. Although multiple disease syndromes were identified that contributed to mortality and, in combination, likely limited the ENS muskox population, further holistic investigations of disease agents, trace mineral status, and nutritional factors in conjunction with intensive demographic and environmental analyses would provide a better understanding of factors that influence Alaskan muskox populations. [ABSTRACT FROM AUTHOR]

The desire to see free ranging large carnivores in their natural habitat is a driver of tourism in protected areas around the globe. However, large carnivores are wide-ranging and subject to human-caused mortality outside protected area boundaries. The impact of harvest (trapping or hunting) on wildlife viewing opportunities has been the subject of intense debate and speculation, but quantitative analyses have been lacking. We examined the effect of legal harvest of wolves (Canis lupus) along the boundaries of two North American National Parks, Denali (DNPP) and Yellowstone (YNP), on wolf viewing opportunities within the parks during peak tourist season. We used data on wolf sightings, pack sizes, den site locations, and harvest adjacent to DNPP from 1997–2013 and YNP from 2008–2013 to evaluate the relationship between harvest and wolf viewing opportunities. Although sightings were largely driven by wolf population size and proximity of den sites to roads, sightings in both parks were significantly reduced by harvest. Sightings in YNP increased by 45% following years with no harvest of a wolf from a pack, and sightings in DNPP were more than twice as likely during a period with a harvest buffer zone than in years without the buffer. These findings show that harvest of wolves adjacent to protected areas can reduce sightings within those areas despite minimal impacts on the size of protected wolf populations. Consumptive use of carnivores adjacent to protected areas may therefore reduce their potential for non-consumptive use, and these tradeoffs should be considered when developing regional wildlife management policies. [ABSTRACT FROM AUTHOR]

Migration is an important component of the life history of many animals, but persistence of large-scale terrestrial migrations is being challenged by environmental changes that fragment habitats and create obstacles to animal movements. In northern Alaska, the Central Arctic herd (CAH) of barren-ground caribou (Rangifer tarandus granti) is known to migrate over large distances, but the herd’s seasonal distributions and migratory movements are not well documented. From 2003–2007, we used GPS radio-collars to determine seasonal ranges and migration routes of 54 female caribou from the CAH. We calculated Brownian bridges to model fall and spring migrations for each year and used the mean of these over all 4 years to identify areas that were used repeatedly. Annual estimates of sizes of seasonal ranges determined by 90% fixed kernel utilization distributions were similar between summer and winter (X̅ = 27,929 SE = 1,064 and X̅ = 26,585 SE = 4912 km2, respectively). Overlap between consecutive summer and winter ranges varied from 3.3–18.3%. Percent overlap between summer ranges used during consecutive years (X̅ = 62.4% SE = 3.7%) was higher than for winter ranges (X̅ = 42.8% SE = 5.9%). Caribou used multiple migration routes each year, but some areas were used by caribou during all years, suggesting that these areas should be managed to allow for continued utilization by caribou. Restoring migration routes after they have been disturbed or fragmented is challenging. However, prior knowledge of movements and threats may facilitate maintenance of migratory paths and seasonal ranges necessary for long-term persistence of migratory species. [ABSTRACT FROM AUTHOR]

Test results are presented for rotordynamic characteristics of hole-pattern-stator annular gas seals at a 70 bar supply pressures with a running speed of 20,200 rpm. Leakage results are presented for these conditions and the additional speeds: 10,200 and 15,300 rpm. Hole-depth is the principal test variable of interest. Most published annular test data for these seals have a hole diameter of 3.175 mm and a hole depth of 3.302 mm. For this work, with the 3.175 mm hole diameter, additional results are presented for shallow (1.905 mm) and deep (6.604 mm) hole depths. Test results show a pronounced dependence of leakage and rotordynamic behavior on hole depth. Test results show much better leakage performance for the shallow-hole-depth seal in both leakage and rotordynamic performance. Compressor manufacturers and users will need to decide whether this observed performance improvement is worth trying in real machines. [ABSTRACT FROM AUTHOR]