487 research outputs found

    Comparative Pollination Efficacies of Bees on Raspberry and the Management of \u3ci\u3eOsmia lignaria\u3c/i\u3e for Late Blooming Crops

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    Unlike other rosaceous fruit crops such as apple and cherry, commercial raspberry cultivars are largely self-fertile and can set fruit in the absence of pollinators. However, their floral morphology often prevents complete self-pollaintion. Incomplete pollination yields unmarketable small or crumbly fruits. Insect visitation is therefore essential to maximizing raspberry yield. Honey bees are typically used to pollinate commercial raspberry; however, escalating prices for hive rentals coupled with increasing acreage encourage evaluation of other manageable pollinators. Bumble bees (Bombus spp.) and several mason bees (Osmia spp.) are promising raspberry pollinators. Five bee species were evaluated and compared for their single-visit pollination efficacies on raspberry. From this a pollinator effectiveness index was created and an estimation of the minimum number of visits required to maximize fruit set was calculated. This estimation was then experimentally verified. Finally, in an attempt to synchronize their brief activity period with raspberry bloom, winter management options aimed at delaying the emergence of the mason bee, O. lignaria, were investigated. All five bee species proved excellent pollinators of raspberry. None of the alternative manageable species greatly outperformed honey bees. For this reason honey bees remain the most economical and practical option for open-field raspberry pollination. The adoption of alternative manageable bees could still be justified in other production systems, such as high-tunnel or greenhouse grown raspberry, which hamper honey bees’ ability to forage effectively. The pollinator effectiveness score for honey bees suggested that as few as two visits can achieve maximum fruit set. This estimate was confirmed through experimentation on three different red raspberry cultivars. For two of these cultivars, just one visit yielded drupelet counts similar to openly-pollinated flowers. This information can be used to help refine stocking density estimates for honey bees on raspberry. Wintering bees at 0° or -3° C rather than 4° C effectively delayed emergence of O. lignaria by more than a month without any impact on post-winter performance. These results suggest winter storage at near freezing temperatures is a viable management option for the use of O. lignaria with later-blooming crops

    On Nachbin's problem concerning uniformizable ordered spaces

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    Contesting categories: cross-border marriages from the perspectives of the state, spouses and researchers

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    Marriages that involve the migration of at least one of the spouses challenge two intersecting facets of the politics of belonging: the making of the ‘good and legitimate citizens’ and the ‘acceptable family’. In Europe, cross-border marriages have been the target of increasing state controls, an issue of public concern and the object of scholarly research. The study of cross-border marriages and the ways these marriages are framed is inevitably affected by states’ concerns and priorities. There is a need for a reflexive assessment of how the categories employed by state institutions and agents have impacted the study of cross-border marriages. The introduction to this Special Issue analyses what is at stake in the regulation of cross-border marriages and how European states use particular categories (e.g. ‘sham’, ‘forced’ and ‘mixed’ marriages) to differentiate between acceptable and non-acceptable marriages. When researchers use these categories unreflexively, they risk reproducing nation-centred epistemologies and reinforcing state-informed hierarchies and forms of exclusion. We suggest ways to avoid these pitfalls: differentiating between categories of analysis and categories of practice, adopting methodologies that do not mirror nation-states’ logic and engaging with general social theory outside migration studies. The empirical contributions of the Special Issue offer new insights into a timely topic

    Exploring the cost and performance benefits of AWS Step Functions using a data processing pipeline

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    In traditional cloud computing, dedicated hardware is substituted by dynamically allocated, utility-oriented resources such as virtualized servers. While cloud services are following the pay-as-you-go pricing model, resources are billed based on instance allocation and not on the actual usage, leading the customers to be charged needlessly. In serverless computing, as exemplified by the Function-as-a-Service (FaaS) model where functions are the basic resources, functions are typically not allocated or charged until invoked or triggered. Functions are not applications, however, and to build compelling serverless applications they frequently need to be orchestrated with some kind of application logic. A major issue emerging by the use of orchestration is that it complicates further the already complex billing model used by FaaS providers, which in combination with the lack of granular billing and execution details offered by the providers makes the development and evaluation of serverless applications challenging. Towards shedding some light into this matter, in this work we extensively evaluate the state-of-the-art function orchestrator AWS Step Functions (ASF) with respect to its performance and cost. For this purpose we conduct a series of experiments using a serverless data processing pipeline application developed as both ASF Standard and Express workflows. Our results show that Step Functions using Express workflows are economical when running short-lived tasks with many state transitions. In contrast, Standard workflows are better suited for long-running tasks, offering in addition detailed debugging and logging information. However, even if the behavior of the orchestrated AWS Lambda functions influences both types of workflows, Step Functions realized as Express workflows get impacted the most by the phenomena affecting Lambda functions

    Association of the 894G>T polymorphism in the endothelial nitric oxide synthase gene with risk of acute myocardial infarction

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    Background: This study was designed to investigate the association of the 894G>T polymorphism in the eNOS gene with risk of acute myocardial infarction (AMI), extent of coronary artery disease (CAD) on coronary angiography, and in-hospital mortality after AMI. Methods: We studied 1602 consecutive patients who were enrolled in the GEMIG study. The control group was comprised by 727 individuals, who were randomly selected from the general adult population. Results: The prevalence of the Asp298 variant of eNOS was not found to be significantly and independently associated with risk of AMI (RR = 1.08, 95%CI = 0.77–1.51, P = 0.663), extent of CAD on angiography (OR = 1.18, 95%CI = 0.63–2.23, P = 0.605) and in-hospital mortality (RR = 1.08, 95%CI = 0.29–4.04, P = 0.908). Conclusion: In contrast to previous reports, homozygosity for the Asp298 variant of the 894G>T polymorphism in the eNOS gene was not found to be associated with risk of AMI, extent of CAD and in-hospital mortality after AM

    Amylin in the periphery II: An updated mini-review

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    Amylin is a polypeptide that is cosecreted with insulin from the beta cells of the pancreas. Therefore, in states of diabetes in which the beta-cell mass is largely depleted or dysfunctional, insulin and amylin secretion are also lost or dysregulated. While the soluble monomeric form of amylin acts as a hormone that alters physiological responses related to feeding and acts as a specific growth factor, there has been renewed interest in the less-soluble oligomeric and insoluble polymeric forms of human (also monkey and cat) amylin that may contribute to the establishment of a pathophysiological pathway to overt diabetes. With this discovery has grown the hope of minimizing, with appropriate therapy, these toxic forms to preserve the functional (c) not-cell mass. Human beta cells may also be more vulnerable to these forms and one risk factor, a higher fat diet, may promote toxic forms. The generation and utilities of transgenic rodent models, which express enhanced levels of human amylin, have been accompanied by strategies that may lead to the reduction of toxic forms and associated risk factors. The successful definition and faithful expression of the physiological receptors (and complexes) for amylin that may differ for each target organ is an important development in the field of amylin research generally. Besides the heuristic value for the understanding of the molecular biology of receptors, the opportunity to screen and identify nonpeptide analogues that bind the physiological receptors has important implications for biomedicine and clinical practice in relation to treatments for diabetic complications, bone diseases, and eating disorders. In particular, in their capacities to mimic the effects of amylin as a growth factor, amylin analogues may prove useful in the stimulation of beta-cell mass (in conjunction with other factors), reduce the activity of the osteoclast population, and stimulate the regeneration of proximal tubules following toxic insult (and thus avoid the development of renal insufficiency)

    Fructose-1,6-Bisphosphatase Overexpression in Pancreatic β-Cells Results in Reduced Insulin Secretion : A New Mechanism for Fat-Induced Impairment of β-Cell Function

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    OBJECTIVE—Fructose-1,6-bisphosphatase (FBPase) is a gluconeogenic enzyme that is upregulated in islets or pancreatic β-cell lines exposed to high fat. However, whether specific β-cell upregulation of FBPase can impair insulin secretory function is not known. The objective of this study therefore is to determine whether a specific increase in islet β-cell FBPase can result in reduced glucose-mediated insulin secretion

    On the origin of the λ\lambda-transition in liquid Sulphur

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    Developing a novel experimental technique, we applied photon correlation spectroscopy using infrared radiation in liquid Sulphur around TλT_\lambda, i.e. in the temperature range where an abrupt increase in viscosity by four orders of magnitude is observed upon heating within few degrees. This allowed us - overcoming photo-induced and absorption effects at visible wavelengths - to reveal a chain relaxation process with characteristic time in the ms range. These results do rehabilitate the validity of the Maxwell relation in Sulphur from an apparent failure, allowing rationalizing the mechanical and thermodynamic behavior of this system within a viscoelastic scenario.Comment: 5 pages, 4 eps figures, accepted in Phys. Rev. Let
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