909 research outputs found

    Following de novo triglyceride dynamics in ovaries of Aedes aegypti during the previtellogenic stage

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    Understanding the molecular and biochemical basis of egg development is a central topic in mosquito reproductive biology. Lipids are a major source of energy and building blocks for the developing ovarian follicles. Ultra-High Resolution Mass Spectrometry (UHRMS) combined with in vivo metabolic labeling of follicle lipids with deuterated water (2H2O) can provide unequivocal identification of de novo lipid species during ovarian development. In the present study, we followed de novo triglyceride (TG) dynamics during the ovarian previtellogenic (PVG) stage (2–7 days post-eclosion) of female adult Aedes aegypti. The incorporation of stable isotopes from the diet was evaluated using liquid chromatography (LC) in tandem with the high accuracy (\u3c 0.3 ppm) and high mass resolution (over 1 M) of a 14.5 T Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (14.5 T FT-ICR MS) equipped with hexapolar detection. LC-UHRMS provides effective lipid class separation and chemical formula identification based on the isotopic fine structure. The monitoring of stable isotope incorporation into de novo incorporated TGs suggests that ovarian lipids are consumed or recycled during the PVG stage, with variable time dynamics. These results provide further evidence of the complexity of the molecular mechanism of follicular lipid dynamics during oogenesis in mosquitoes

    Author Correction: Following de novo triglyceride dynamics in ovaries of Aedes aegypti during the previtellogenic stage (Scientific Reports, (2021), 11, 1, (9636), 10.1038/s41598-021-89025-6)

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    In the original version of this Article Veronika Michalkova was incorrectly affiliated with ‘Institute of Parasitology, Biology Centre CAS, Ceske Budejovice, Czech Republic’. The correct affiliations are listed below. Department of Biology, Florida International University, Miami, FL, USA. Institute of Zoology, Slovak Academy of Sciences, Dubravska cesta 9, 84506 Bratislava, Slovakia. The original Article and accompanying Supplementary Information file have been corrected

    Pipes to Earth's subsurface: the role of atmospheric conditions in controlling air transport through boreholes and shafts

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    Understanding air exchange dynamics between underground cavities (e.g., caves, mines, boreholes, etc.) and the atmosphere is significant for the exploration of gas transport across the Earth–atmosphere interface. Here, we investigated the role of atmospheric conditions in controlling air transport inside boreholes using in situ field measurements. Three geometries were explored: (1) a narrow and deep shaft (0.1&thinsp;m wide and 27&thinsp;m deep), ending in a large underground cavity; (2) the same shaft after the pipe was lowered and separated from the cavity; and (3) a deep large-diameter borehole (59&thinsp;m deep and 3.4&thinsp;m wide). Absolute humidity was found to be a reliable proxy for distinguishing between atmospheric and cavity air masses (mainly during the winter and spring seasons) and thus to explore air transport through the three geometries. Airflow directions in the first two narrow-diameter geometries were found to be driven by changes in barometric pressure, whereas airflow in the large-diameter geometry was correlated primarily with the diurnal cycles of ambient atmospheric temperature. CO2 concentrations of  ∼ 2000&thinsp;ppm were found in all three geometries, indicating that airflow from the Earth's subsurface into the atmosphere may also be significant in the investigation of greenhouse gas emissions.</p

    An Analysis of Private School Closings

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    We add to the small literature on private school supply by exploring exits of K-12 private schools. We find that the closure of private schools is not an infrequent event, and use national survey data from the National Center for Education Statistics to study closures of private schools. We assume that the probability of an exit is a function of excess supply of private schools over the demand, as well as the school's characteristics such as age, size, and religious affiliation. Our empirical results generally support the implications of the model. Working Paper 07-0

    The potential of trading activity income to fund third sector organisations operating in deprived areas

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    In the United Kingdom, as in other countries, Third Sector Organisations (TSOs) have been drawn towards income sources associated with trading activities (Teasdale, 2010), but many remain reliant on grant funding to support such activities (Chell, 2007). Using a multivariate analysis approach and data from the National Survey of Charities and Social Enterprises (NSCSE), it is found that trading activities are used relatively commonly in deprived areas. These organisations are also more likely to attempt to access public sector funds. This suggests policy-makers need to consider the impact of funding cuts on TSOs in the most deprived areas as TSOs are unlikely achieve their objectives without continuing support

    Evaluation Research and Institutional Pressures: Challenges in Public-Nonprofit Contracting

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    This article examines the connection between program evaluation research and decision-making by public managers. Drawing on neo-institutional theory, a framework is presented for diagnosing the pressures and conditions that lead alternatively toward or away the rational use of evaluation research. Three cases of public-nonprofit contracting for the delivery of major programs are presented to clarify the way coercive, mimetic, and normative pressures interfere with a sound connection being made between research and implementation. The article concludes by considering how public managers can respond to the isomorphic pressures in their environment that make it hard to act on data relating to program performance.This publication is Hauser Center Working Paper No. 23. The Hauser Center Working Paper Series was launched during the summer of 2000. The Series enables the Hauser Center to share with a broad audience important works-in-progress written by Hauser Center scholars and researchers

    Why Social Enterprises Are Asking to Be Multi-stakeholder and Deliberative: An Explanation around the Costs of Exclusion.

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    The study of multi-stakeholdership (and multi-stakeholder social enterprises in particular) is only at the start. Entrepreneurial choices which have emerged spontaneously, as well as the first legal frameworks approved in this direction, lack an adequate theoretical support. The debate itself is underdeveloped, as the existing understanding of organisations and their aims resist an inclusive, public interest view of enterprise. Our contribution aims at enriching the thin theoretical reflections on multi-stakeholdership, in a context where they are already established, i.e. that of social and personal services. The aim is to provide an economic justification on why the governance structure and decision-making praxis of the firm needs to account for multiple stakeholders. In particular with our analysis we want: a) to consider production and the role of firms in the context of the “public interest” which may or may not coincide with the non-profit objective; b) to ground the explanation of firm governance and processes upon the nature of production and the interconnections between demand and supply side; c) to explain that the costs associated with multi-stakeholder governance and deliberation in decision-making can increase internal efficiency and be “productive” since they lower internal costs and utilise resources that otherwise would go astray. The key insight of this work is that, differently from major interpretations, property costs should be compared with a more comprehensive range of costs, such as the social costs that emerge when the supply of social and personal services is insufficient or when the identification of aims and means is not shared amongst stakeholders. Our model highlights that when social costs derived from exclusion are high, even an enterprise with costly decisional processes, such as the multistakeholder, can be the most efficient solution amongst other possible alternatives

    From Providers to PHOs: an institutional analysis of nonprofit primary health care governance in New Zealand

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    Policy reforms to primary health care delivery in New Zealand required government-funded firms overseeing care delivery to be constituted as nonprofit entities with governance shared between consumer and producers. This paper examines the consumer and producer interests in the allocation of ownership and control of New Zealand firms delivering primary health care utilising theories of competition in the markets for ownership and control of firms. Consistent with pre-reform patterns of ownership and control provider interests appear to have exerted effective control over the formation and governance of the new entities in all but a few cases where community (consumer) control was already established. Their ability to do so is implied from the absence of a defined ownership stake via which the balance of governance control could shift as a consequence of changes to incentives facing the different stakeholding groups. It appears that the pre-existing patterns will prevail and further intervention will be required if policymakers are to achieve their underlying aims
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