Proximity to chronic wasting disease,perceived risk,and social trust in the managing agency

This article examined relationships between proximity to chronic wasting disease (CWD) and perceived risk and trust. The sample included 1,606 hunters in one of 10 northern Illinois counties with CWD, 1,958 hunters in a non-CWD county adjacent to these counties with CWD, and 2,099 hunters from the remaining non-CWD counties in Illinois. Compared to hunters in non-CWD counties, those in CWD counties were hypothesized to: (a) perceive more risk of CWD to humans, (b) perceive more risk of CWD to deer, (c) report less trust in the Illinois Department of Natural Resources (IDNR) CWD information, and (d) have less trust in the IDNR management of CWD. The first two hypotheses were not supported, as hunters in CWD counties perceived less risk to humans and deer than did respondents in non-CWD counties. Hunters in CWD counties, however, were less trusting of the IDNR information and management compared to the other hunters.     

Innovative approaches to genome editing in avian species

The tools available for genome engineering have significantly improved over the last 5 years, allowing scientist to make precise edits to the genome. Along with the development of these new genome editing tools has come advancements in technologies used to deliver them. In mammals genome engineering tools are typically delivered into in vitro fertilized single cell embryos which are subsequently cultured and then implanted into a recipient animal.In avian species this is not possible, so other methods have been developed for genome engineering in birds. The most common involves in vitro culturing of primordial germ cells(PGCs), which are cells that migrate through the embryonic circulatory system to the developing gonad and colonize the gonad, eventually differentiating into the gonadocytes which produce either sperm or ova. While in culture the PGCs can be modified to carry novel transgenes or gene edits, the population can be screened and enriched, and then transferred into a recipient embryo. The largest drawback of PGC culture is that culture methods do not transfer well across avian species, thus there are reliable culture methods for only a few species including the chicken. Two newer technologies that appear to be more easily adapted in a wider range of avian species are direct injection and sperm transfection assisted gene editing(STAGE).The direct injection method involves injecting genome engineering tools into the circulatory system of the developing embryo just prior to the developmental time point when the PGCs are migrating to the gonads. The genome engineering tools are complexed with transfection reagents, allowing for in vivo transfection of the PGCs. STAGE utilizes sperm transfection to deliver genome engineering tools directly to the newly fertilized embryo. Preliminary evidence indicates that both methodologies have the potential to be adapted for use in birds species other than the chicken, however further work is needed in this area.     

Calibration and use of plate meter regressions for pasture mass estimation in an Appalachian silvopasture

A plate meter for measuring pasture mass was calibrated at Agroforestry Research Site in Blacksburg, Virginia, USA, using six ungrazed plots of established tall fescue overseeded with orchardgrass. Each plot was interplanted with bare root honey locust and black walnut seedlings spaced along a gradient ranging from 1.8 to 11.0 m. Plate height (PH) of forage between trees was measured by placing a 46 mm × 46 mm × 5.6-mm-thick acrylic plastic plate meter on pasture canopy at six locations four times a season. PH was measured between ground and plate as it rested on pasture canopy. To calibrate the plate meter against a known dry matter yield, 50 × 50-cm clip plots followed each PH measurement. The resulting regression slope was 421 kg ha^?1 cm^?1, with an r ² value of 0.86. Unique research investigating the response of forage mass to site elevation is presented using the developed equation. The field-calibrated regression slope of ruler height (RH) to PH was 1.71 cm cm^?1, with an r ² value of 0.87, showing good correlation between RH and PH. A comparable regional regression equation was found to adequately predict independent calibration clip plot data reported at this site. The results support the application of regression equations for estimating pasture mass in areas having similar climates and pasture composition.     

Leaching of dissolved organic carbon and nitrogen under cotton farming systems in a Vertisol

Leaching with deep drainage is one of the loss pathways of carbon (C) and nitrogen (N) in cropping fields. However, field studies in irrigated row cropping systems are sparse. A 3‐year investigation on C and N leaching associated with deep drainage was overlaid on a long‐term experiment on tillage practices and crop rotations in Australia. The treatments included cotton (Gossypium hirsutum L.) monoculture and cotton–wheat (Triticum aestivum L.) or maize (Zea maize L.) rotations with maximum or minimum tillage. The deep drainage C and N concentrations at 0.6 and 1.2 m depth were measured after furrow irrigation with ceramic cup samplers during the 2014–15, 2015–16 and 2016–17 cotton seasons. Pre‐planting dissolved organic carbon (DOC) concentration in soil at 0.6–1.2 m depth during 2016–17 was 64 mg kg^?1 for maximum tilled cotton monoculture, 36 mg kg^?1 for minimum tilled cotton monoculture and 39 mg kg^?1 for cotton–wheat, and in maize and cotton subplots 51 and 41 mg kg^?1, respectively. Post‐harvest DOC values in soil were similar in all treatments (average of 32 mg DOC kg^?1). Total organic carbon (TOC) losses in deep drainage were equal to 2%–30% of TOC gained in irrigation water. Oxidized N losses in deep drainage ranged from 0.7% to 12% of applied N (260 kg ha^?1). NOx‐N concentrations in leachate under maize systems (20 mg L^?1) were up to 73% lower than those in cotton systems (75 mg L^?1). Maize sown in rotation with cotton can improve cotton yield, reduce N leaching and improve N use efficiency of subsequent cotton.     

Potential direct and indirect effects of climate change on a shallow natural lake fish assemblage

Much uncertainty exists around how fish communities in shallow lakes will respond to climate change. In this study, we modelled the effects of increased water temperatures on consumption and growth rates of two piscivores (northern pike [Esox lucius] and largemouth bass [Micropterus salmoides]) and examined relative effects of consumption by these predators on two prey species (bluegill [Lepomis macrochirus] and yellow perch [Perca flavescens]). Bioenergetics models were used to simulate the effects of climate change on growth and food consumption using predicted 2040 and 2060 temperatures in a shallow Nebraska Sandhill lake, USA. The patterns and magnitude of daily and cumulative consumption during the growing season (April–October) were generally similar between the two predators. However, growth of northern pike was always reduced (?3 to ?45% change) compared to largemouth bass that experienced subtle changes (4 to ?6% change) in weight by the end of the growing season. Assuming similar population size structure and numbers of predators in 2040–2060, future consumption of bluegill and yellow perch by northern pike and largemouth bass will likely increase (range: 3–24%), necessitating greater prey biomass to meet future energy demands. The timing of increased predator consumption will likely shift towards spring and fall (compared to summer), when prey species may not be available in the quantities required. Our findings suggest that increased water temperatures may affect species at the edge of their native range (i.e. northern pike) and a potential mismatch between predator and prey could exist.     

The effects of cultivation history on forest recovery in fallows in the Eastern Arc Mountain, Tanzania

Using fallows under shifting cultivation systems as a case study, we examined the effects of landuse history (cultivation duration and cropping strategies) on rate and extent of forest recovery. Cultivation duration and five cropping strategies were investigated post facto, indirectly, and with regards to their effect on the structure (basal area, BA and stand complexity, C_HCI) and diversity (Fisher's α) of forests in fallows. Data were generated from vegetation surveys conducted in the Nguru Mountain block of the Eastern Arc Mountains, Tanzania. The surveys were conducted in primary forests, ongoing farms, and fallows that had been out of production for 1-31 years (N = 109, plot size = 0.1 ha). Recovery patterns between lowland (300-800 m) and submontane (800-1600 m) elevations varied substantially. BA and C_HCI recovery levels were consistently higher in submontane fallows. None of the fallows had attained BA and C_HCI levels equivalent to those of primary forests; α in lowland fallows, however, was 124% of primary forest levels. Forest recovery was limited to fallows whose cultivation period was ≤16 years. Recovery was fastest and highest in fallows located within a dense primary/old growth forest matrix. The findings provide a more thorough understanding of how local farming practices affect forest recovery. Improving the recovery outcomes of fallows that are located outside the old growth forest matrix will require (a) more strategic inclusion of remnant trees, (b) drastically shorter cultivation periods, and (c) human intervention through assisted regeneration.     

微粉碎设备——高透锤片式粉碎机(续)

6 锤片 各类锤片用于不同锤片式粉碎机的粉碎.锤片最长使用寿命和最有效操作首选锤片末端.锤片可1孔(2角)工作或2孔(4角)用于粉碎.锤片1孔通常优先保持转子平衡,使锤片损坏的可能性降到最低.     

The Palaeozoic, Mesozoic and Early Cenozoic fishes of Africa

Africa has provided many fossil fishes from sediments laid down over a 400 million year period. The large array of fossil fishes come from diverse localities throughout the continent, representing a variety of environments. The marine fossil fishes of Africa have not been reviewed as a whole, while the freshwater Cenozoic fishes of Africa were last reviewed over 25 years ago. Since that time, many new finds have increased our knowledge of the history of African fishes. This paper summarizes the known fish fossils, excluding otoliths, from marine and freshwater deposits throughout Africa from the Palaeozoic, Mesozoic and first part of the Cenozoic (Palaeogene). Much new work is ongoing, in areas such as Mali and South Africa, from which more information on the ichthyofaunas should come to light. New information presented here includes the Eocene site of Mahenge, Tanzania, from which have come the oldest known members of the family Cichlidae.