The radiolarian fauna at the ice edge in the Greenland Sea during summer, 1988

Radiolaria were sampled from the plankton at 18 stations during two cruises in the Greenland Sea during summer, 1988. A total of 43 species or categories of radiolaria was found, but over 90% of the radiolarian fauna was dominated by adults or juveniles of 4 species: the spumellarian, Actinomma leptodermum and the nassellaria, Amphimelissa setosa, Pseudodictyophimus gracilipes, and Peridium longispinum. The stations sampled ranged from ice-covered areas high in nutrients to open water areas which were depleted in nutrients. These stations encompassed a gradient in the composition of the radiolarian fauna from an assemblage dominated by juveniles and adults of A. setosa and P. gracilipes at the ice edge to one dominated by Actinomma juveniles, A. leptodermum, and P. longispinum in open water. The total abundance of radiolaria correlated with integrated phaeopigment, but not with chlorophyll a. In discriminant function analysis the \u27ice edge\u27 radiolarian species listed above correlated well with chlorophyll a and phaeopigments, while the \u27open water\u27 species did not. Several water masses occur in the area, which complicates the interpretation considerably, but the data are consistent with the development of a radiolarian population in tempo with, and in all probability linked successionally to the development of the phytoplankton—microplankton bloom

Partial Characterization and Comparison of Rhizobia from Astragalus Flexuosus Glycyrrhiza Lepidota, and Trifolium Spp.

Biological nitrogen fixation, a means of alleviating our increasing dependence on synthesized nitrogen fertilizers, is being studied with renewed interest. Production of nitrogen fertilizer requires large amounts of natural gas and other non-renewable energy sources, while the energy for biological nitrogen fixation is derived either directly or indirectly from photosynthesis. With only limited supplies of natural gas and an increasing population, and thus increasing demand for food, the advantages and even necessity of understanding and enhancing biological nitrogen is obvious. The nitrogenase enzyme complex which catalyzes the reduction of dinitrogen to ammonia is possessed by a limited number of species of procaryotic organisms. The nitrogen fixing procaryotes are categorized as non-symbiotic (free living) nitrogen fixers and symbiotic nitrogen fixers. Nitrogen fixation by the leguminous plant-rhizobium bacteria symbiosis is important because a portion of the fixed nitrogen accumulated is harvested as high protein foods or plant forage while the remaining fixed nitrogen eventually enters the soil. Studies on the rhizobia from cultivated legumes have been extensive and economically rewarding. However, rhizobia from thousands of other legumes including rhizobia symbiosing with legumes native to South Dakota have been inadequately studied. As a result, information on the symbiotic nitrogen fixing capabilities and characteristics of rhizobia from most leguminous species varies from substantial to nonexistent. This study was initiated with the purpose of isolating and characterizing the rhizobia from Astragalus flexuosus (flexile milk vetch) and Glycyrrhiza lepidota (American licorice). For comparison, strains of Rhizobium trifolii, which symbiose with Trifolium spp. (true clovers) and have been extensively studied, were isolated from Trifolium spp. and characterized

The NOMA track module on nutrition, human rights and governance: Part 2. A transnational curriculum using a human rights-based approach to foster key competencies in nutrition professionals

Background. In response to the challenge of the global health needs of the 21st century, four academic institutions in Norway, South Africa and Uganda,each offering a Master’s degree in nutrition, collaboratively developed the NOrwegian MAsters (NOMA) track module on nutrition, human rights andgovernance, integrating a human rights-based approach into graduate education in nutrition.Objective. To capture students’ perceptions about the NOMA track module, focusing on the development of key competencies.Methods. Employing a qualitative approach, 20 (91% response rate) in-depth telephonic interviews were conducted with participating students, voicerecorded and transcribed. Through an inductive process, emerging themes were used to compile a code list for content analysis of the transcribed text. Relevant themes were reported according to the professionals’ roles described by the CanMEDS competency framework.Results. Participation in the module enhanced key competencies in the students, e.g. communication skills and the adoption of a holistic approach tointeraction with people or communities. Their role as collaborator was enhanced by their learning to embrace diversity and cultural differences and similarities. Students had to adapt to different cultures and educational systems. They were inspired to contribute in diverse contexts and act as agents for change in the organisations in which they may work or act as leaders or co-ordinators during interaction with community groups and policy makers. Higher education institutions offering transnational modules should support lecturers to manage the inherent diversity in the classroom as a way of enhancing student performance.Conclusion. The development of future transprofessional modules will benefit from the inclusion of desirable key competencies as part of the moduleoutcomes by following a competency by design process

Predator-prey-subsidy population dynamics on stepping-stone domains with dispersal delays

We examine the role of the travel time of a predator along a spatial network on predator-prey population interactions, where the predator is able to partially or fully sustain itself on a resource subsidy. The impact of access to food resources on the stability and behaviour of the predator-prey-subsidy system is investigated, with a primary focus on how incorporating travel time changes the dynamics. The population interactions are modelled by a system of delay differential equations, where travel time is incorporated as discrete delay in the network diffusion term in order to model time taken to migrate between spatial regions. The model is motivated by the Arctic ecosystem, where the Arctic fox consumes both hunted lemming and scavenged seal carcass. The fox travels out on sea ice, in addition to quadrennially migrating over substantial distances. We model the spatial predator-prey-subsidy dynamics through a “stepping-stone” approach. We find that a temporal delay alone does not push species into extinction, but rather may stabilize or destabilize coexistence equilibria. We are able to show that delay can stabilize quasi-periodic or chaotic dynamics, and conclude that the incorporation of dispersal delay has a regularizing effect on dynamics, suggesting that dispersal delay can be proposed as a solution to the paradox of enrichment

Large-scale simulations of H and He reionization and heating driven by stars and more energetic sources

We present simulations of cosmic reionization and reheating from z = 18 to z = 5, investigating the role of stars (emitting soft UV-photons), nuclear black holes (BHs, with power-law spectra), X-ray binaries (XRBs, with hard X-ray dominated spectra), and the supernova-associated thermal bremsstrahlung of the diffuse interstellar medium (ISM, with soft X-ray spectra). We post-process the hydrodynamical simulation MassiveBlack-II (MBII) with multifrequency ionizing radiative transfer. The source properties are directly derived from the physical environment of MBII, and our only real free parameter is the ionizing escape fraction fesc. We find that, among the models explored here, the one with an escape fraction that decreases with decreasing redshift yields results most in line with observations, such as of the neutral hydrogen fraction and the Thomson scattering optical depth. Stars are the main driver of hydrogen reionization and consequently of the thermal history of the intergalactic medium (IGM). We obtain = 0.99998 at z = 6 for all source types, with volume-averaged temperatures < T > ∼ 20 000 K. BHs are rare and negligible to hydrogen reionization, but conversely they are the only sources that can fully ionize helium, increasing local temperatures by ∼104 K. The thermal and ionization state of the neutral and lowly ionized hydrogen differs significantly with different source combinations, with ISM and (to a lesser extent) XRBs, playing a significant role and, as a consequence, determining the transition from absorption to emission of the 21-cm signal from neutral hydrogen

In vivo evidence that truncated trkB.T1 participates in nociception

Brain-Derived Neurotrophic Factor (BDNF) is a central nervous system modulator of nociception. In animal models of chronic pain, BDNF exerts its effects on nociceptive processing by binding to the full-length receptor tropomyosin-related kinase B (trkB.FL) and transducing intracellular signaling to produce nocifensive behaviors. In addition to trkB.FL, the trkB locus also produces a widely-expressed alternatively-spliced truncated isoform, trkB.T1. TrkB.T1 binds BDNF with high affinity; however the unique 11 amino acid intracellular cytoplasmic tail lacks the kinase domain of trkB.FL. Recently, trkB.T1 was shown to be specifically up-regulated in a model of HIV-associated neuropathic pain, potentially implicating trkB.T1 as a modulator of nociception. Here, we report that trkB.T1 mRNA and protein is up-regulated in the spinal dorsal horn at times following antiretroviral drug treatment and hind paw inflammation in which nocifensive behaviors develop. While genetic depletion of trkB.T1 did not affect baseline mechanical and thermal thresholds, the absence of trkB.T1 resulted in significant attenuation of inflammation- and antiretroviral-induced nocifensive behaviors. Our results suggest that trkB.T1 up-regulation following antiretroviral treatment and tissue inflammation participates in the development and maintenance of nocifensive behavior and may represent a novel therapeutic target for pain treatment

Integrated Initiating Event Performance Indicators

The U.S. Nuclear Regulatory Commission Industry Trends Program (ITP) collects and analyses industry-wide data, assesses the safety significance of results, and communicates results to Congress and other stakeholders. This paper outlines potential enhancements in the ITP to comprehensively cover the Initiating Events Cornerstone of Safety. Future work will address other cornerstones of safety. The proposed Tier 1 activity involves collecting data on ten categories of risk-significant initiating events, trending the results, and comparing early performance with prediction limits (allowable numbers of events, above which NRC action may occur). Tier 1 results would be used to monitor industry performance at the level of individual categories of initiating events. The proposed Tier 2 activity involves integrating the information for individual categories of initiating events into a single risk-based indicator, termed the Baseline Risk Index for Initiating Events or BRIIE. The BRIIE would be evaluated yearly and compared against a threshold. BRIIE results would be reported to Congress on a yearly basis

Estimating Loss-of-Coolant Accident Frequencies for the Standardized Plant Analysis Risk Models

The U.S. Nuclear Regulatory Commission maintains a set of risk models covering the U.S. commercial nuclear power plants. These standardized plant analysis risk (SPAR) models include several loss-of-coolant accident (LOCA) initiating events such as small (SLOCA), medium (MLOCA), and large (LLOCA). All of these events involve a loss of coolant inventory from the reactor coolant system. In order to maintain a level of consistency across these models, initiating event frequencies generally are based on plant-type average performance, where the plant types are boiling water reactors and pressurized water reactors. For certain risk analyses, these plant-type initiating event frequencies may be replaced by plant-specific estimates. Frequencies for SPAR LOCA initiating events previously were based on results presented in NUREG/CR-5750, but the newest models use results documented in NUREG/CR-6928. The estimates in NUREG/CR-6928 are based on historical data from the initiating events database for pressurized water reactor SLOCA or an interpretation of results presented in the draft version of NUREG-1829. The information in NUREG-1829 can be used several ways, resulting in different estimates for the various LOCA frequencies. Various ways NUREG-1829 information can be used to estimate LOCA frequencies were investigated and this paper presents two methods for the SPAR model standard inputs, which differ from the method used in NUREG/CR-6928. In addition, results obtained from NUREG-1829 are compared with actual operating experience as contained in the initiating events database

Application of genetic engineering for control of bacterial wilt disease of enset, Ethiopia's sustainability crop

Open Access JournalEnset (Ensete ventricosum (Welw.) Cheesman) is one of the Ethiopia’s indigenous sustainability crops supporting the livelihoods of about 20 million people, mainly in the densely populated South and Southwestern parts of the country. Enset serves as a food security crop for humans, animal feed, and source of fiber for the producers. The production of enset has been constrained by plant pests, diseases, and abiotic factors. Among these constraints, bacterial wilt disease has been the most important limiting factor for enset production since its outbreak five decades ago. There is no known bacterial wilt disease resistant genetic material in the enset genetic pool to transfer this trait to susceptible enset varieties through conventional breeding. Moreover, the absence of effective chemicals against the disease has left farmers without means to combat bacterial wilt for decades. Genetic engineering has been the alternative approach to develop disease resistant plant materials in other crops where traditional breeding tools are ineffective. This review discusses enset cultivation and recent developments addressing the control of bacterial wilt disease in enset and related crops like banana to help design effective strategies

PISA: a political project and a research agenda

PISA (Programme for International Student Assessment) is one of two large scale international comparative projects of student assessment that now exert considerable influence upon school science education policy, the other being TIMSS (Trends in International Mathematics and Science Study). This paper focuses on PISA, now the most influential study. This article outlines the origins of PISA, identifies some of the challenges in its construction and the claims made for it. It argues that while the statistical and methodological aspects of PISA have received much research attention, other elements of PISA have been largely ignored. In particular, there are several outcomes of PISA testing that point towards a significant research agenda. In addition, the political, ideological and economic assumptions underpinning the PISA project have implications for school science curriculum policy that deserve closer scrutiny and debate