Implementing Recall

The use of tests as schoolroom aids to learning has long been advocated. The conditions under which these benefits accrue have not, however, been fully explored. This paper is a summary of one of several recent studies at the University of Iowa which have sought information on this problem. An attempt was made, in the investigation reported below, to compare the effectiveness of a reading and a rereading of factual material with that of a reading and a completion test response. Specifically, three learning conditions were compared: (1) the reading of a selection of factual material followed by the taking of a completion test as a review exercise; (2) a single reading of the factual material, and (3) a reading of the factual material and a rereading of the material as a review exercise. A criterion test administered immediately after learning prodded a measure of retention for the comparison of the three conditions

Explaining Environmental Management System Development: A Stakeholder Approach

Managerial changes are necessary for companies in the Dutch food industry and agribusiness to lessen the environmental impact of their activities. To identify the opportunities or limits of environmental management systems (EMSs), it is important to first understand what influence stakeholders have on EMS development. In an empirical research we found that developmental levels of internally oriented EMSs, which primarily aim at internal administrative procedures, are explained mainly by the frequency of contacts with governmental authorities. For this kind of EMSs, non-commercial stakeholder groups have a major influence on the corporate environmental policy. Externally oriented EMSs, which focus on joint efforts in supply chains, are influenced by commercial groups in the business network (like suppliers, clients and competitors). The development of externally oriented EMSs requires adjustments in the composition of and interaction with the stakeholder environment by governmental agencies as well as managers in the agri-food sector. Opening up towards the stakeholder environment, by (among others) an adjustment of the information system, integrated (supply-chain wide) auditing and licensing, can enhance cost-efficiency, transparency and sustainability.Environmental management, Stakeholders, Environmental policy, Information system, Environmental Economics and Policy,

Anatomical and physiological development of the Xenopus embryonic motor system in the absence of neural activity

Embryos of Xenopus laevis were continually immobilized by immersion in solutions of either chloretone or lidocaine, from the late neural-fold stage to the approximate time of hatching. Such treatment has been shown to result in only transient quantitative effects on swimming behavior. Chronic immobilization was without either immediate or long- term effect on the ventral root output exhibited during “fictive” swimming episodes. Development under these conditions of diminished or absent neural activity similarly had no effects on a number of measures of the size and complexity of motoneuron dendritic arborizations. These results support the premise that the early development of specific neuronal morphology and connectivity may be largely independent of functional activity

Extent change of protected mangrove forest and its relation to wave power exposure on Aldabra Atoll

Mangrove forests, vital for the conservation of biodiversity, protection of coastlines, and carbon capture, are decreasing globally at a rate higher than most other tropical forests. They are threatened by sea level rise, drought and storm surge, especially on low-lying islands where forests are directly exposed to the elements and have limited land area. We investigated changes in the spatial extent of mangroves on Aldabra Atoll, Seychelles – a protected area without direct human pressures, over 21 years using Landsat images. Over the 21-year study period, mean mangrove extent was 1283 ha with an overall net increase of 60 ha (0.23% year-1). The majority of extent changes were small (<2 ha) and contiguous to the existing mangrove extent. We then assessed the relation of mangrove cover change along the lagoon coastline with wave power (rate of energy transfer by waves), using fetch measures and local wind data. We found lower wave power values for stable mangrove areas than for areas that had gained or lost mangroves from 1997 to 2018. We identified wave power thresholds of 2.3 W m-1 for stable mangrove and 7.1 W m-1 for mangrove occurrence. These thresholds might be valuable for assessing threats and sites with the greatest potential for mangrove restoration across similar areas worldwide. Our results highlight the importance of quantifying mangrove extent changes at a local scale to assist with planning for the protection and restoration of this ecologically important habitat, given its vulnerability to the pressures associated with climate change

Increasing Arctic Tundra Flooding Threatens Wildlife Habitat and Survival: Impacts on the Critically Endangered Siberian Crane (Grus leucogeranus)

Climate change is causing Arctic temperatures to increase at least twice as fast as the planet on average. Temperature and precipitation are predicted to continue increasing, such that flooding might become more prevalent in the new Arctic. Increased flooding frequency and extreme flooding events may pose new threats to Arctic biodiversity through habitat disturbance and decreased survival. We used the Siberian crane (Grus leucogeranus) as a model organism to investigate how flooding influences nesting habitat availability and juvenile counts. When spring flooding destroys eggs, adults either do not raise any chicks or have reduced time to prepare them for their long migration to China, thus years with extensive flooding could negatively impact future crane generations. We used nest site observation data from 14 surveys between 1995 and 2019, habitat mapping based on Landsat 8 imagery, and species distribution modeling to predict Siberian crane potential nesting habitat. Nesting habitat loss due to extreme flooding was calculated by overlaying this potential nesting habitat with Global Surface Water data. The percent of potential flooded nest sites varied between 6.7–55% across years, with a significant increase between 2001 and 2018. Extreme flood events, as experienced in 2017 and 2018, eliminated almost half of the potential nesting habitat. Importantly, we found that the percentage of flooded nest sites across years was negatively correlated with the number of observed juveniles. The Arctic lowlands are exposed to seasonal water level fluctuations that species have evolved with and adapted to. Siberian cranes and other species depending on Arctic ecosystems are expected to continue adapting to changing flood conditions, but extreme flood events further threaten the long-term survival of critically endangered species. It is imperative to assess how ecosystems and species respond to climatic extremes to support Arctic conservation strategies

Electron radiation–induced degradation of GaAs solar cells with different architectures

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Variation in Manduca sexta pollination-related floral traits and reproduction in a wild tobacco plant

Most flowering plants depend on animal pollination for successful sexual reproduction. Floral signals such as color, shape, and odor are crucial in establishing this (often mutualistic) interaction. Plant and pollinator phenotypes can vary temporally but also spatially, thus creating mosaic-like patterns of local adaptations. Here, we investigated natural variation in floral morphology, flower volatile emission, and phenology in four accessions of a self-compatible wild tobacco, Nicotiana attenuata, to assess how these traits match the sensory perception of a known pollinator, the hawkmoth Manduca sexta. These accessions differ in floral traits and also in their habitat altitudes. Based on habitat temperatures, the accession occurring at the highest altitude (California) is less likely to be visited by M. sexta, while the others (Arizona, Utah 1, and Utah 2) are known to receive M. sexta pollinations. The accessions varied significantly in flower morphologies, volatile emissions, flower opening, and phenology, traits likely important for M. sexta perception and floral handling. In wind tunnel assays, we assessed the seed set of emasculated flowers after M. sexta visitation and of natural selfed and hand-pollinated selfed flowers. After moth visitations, plants of two accessions (Arizona and Utah 2) produced more capsules than the other two, consistent with predictions that accessions co-occurring with M. sexta would benefit more from the pollination services of this moth. We quantified flower and capsule production in four accessions in a glasshouse assay without pollinators to assess the potential for self-pollination. The two Utah accessions set significantly more seeds after pollen supplementation compared with those of autonomous selfing flowers, suggesting a greater opportunistic benefit from efficient pollinators than the other two. Moreover, emasculated flowers of the accession with the most exposed stigma (Utah 2) produced the greatest seed set after M. sexta visitation. This study reveals intraspecific variation in pollination syndromes that illuminate the potential of a plant species to adapt to local pollinator communities, changing environments, and altered pollination networks