1,472 research outputs found
NEO-INSTITUCIONALISMO: FATORES ORGANIZACIONAIS NA VIDA POLÍTICA
As teorias políticas contemporâneas tendem a retratar a política como um reflexo da sociedade; os fenômenospolíticos como as conseqüências agregadas do comportamento individual; a ação como o resultado deescolhas baseadas no interesse pessoal calculado; a história como sendo eficiente no alcance de desfechossingulares e adequados e a tomada de decisões e a alocação de recursos como os focos centrais da vidapolítica. Entretanto, um pensamento teórico recente na Ciência Política combina elementos desses estilosteóricos com uma preocupação mais antiga a respeito das instituições. Esse neo-institucionalismo enfatizaa autonomia relativa das instituições políticas, as possibilidades de ineficiência na história e a importânciada ação simbólica para um entendimento da política. Tais idéias possuem uma razoável base empírica,mas não se caracterizam por formas teóricas poderosas. Entretanto, pode-se identificar algumas direçõespara a pesquisa teórica nas concepções institucionalistas da ordem política: esse é o nosso objetivo nesteartigo
Testing isosource : stable isotope analysis of a tropical fishery with diverse organic matter sources
Author Posting. © Ecological Society of America, 2006. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecology 87 (2006): 326–333, doi:10.1890/05-0721.We sampled consumers and organic matter sources (mangrove litter, freshwater swamp-forest litter, seagrasses, seagrass epiphytes, and marine particulate organic matter [MPOM]) from four estuaries on Kosrae, Federated States of Micronesia for stable isotope (δ13C and δ34S) analysis. Unique mixing solutions cannot be calculated in a dual-isotope, five-endmember scenario, so we tested IsoSource, a recently developed statistical procedure that calculates ranges in source contributions (i.e., minimum and maximum possible). Relatively high minimum contributions indicate significant sources, while low maxima indicate otherwise. Litter from the two forest types was isotopically distinguishable but had low average minimum contributions (0–8% for mangrove litter and 0% for swamp-forest litter among estuaries). Minimum contribution of MPOM was also low, averaging 0–13% among estuaries. Instead, local marine sources dominated contributions to consumers. Minimum contributions of seagrasses averaged 8–47% among estuaries (range 0–88% among species). Minimum contributions of seagrass epiphytes averaged 5–27% among estuaries (range 0–69% among species). IsoSource enabled inclusion of five organic matter sources in our dual-isotope analysis, ranking trophic importance as follows: seagrasses > seagrass epiphytes > MPOM > mangrove forest > freshwater swamp-forest. IsoSource is thus a useful step toward understanding which of multiple organic matter sources support food webs; more detailed work is necessary to identify unique solutions.This research was funded through a research joint venture
agreement between the USDA and CMP at the University of
Georgia
Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum
This paper describes the eight-day August 2013 test campaign designed to investigate and demonstrate viability of using classical magnetoplasmadynamics to obtain a propulsive momentum transfer via the quantum vacuum virtual plasma. This paper will not address the physics of the quantum vacuum plasma thruster, but instead will describe the test integration, test operations, and the results obtained from the test campaign. Approximately 30-50 micro-Newtons of thrust were recorded from an electric propulsion test article consisting primarily of a radio frequency (RF) resonant cavity excited at approximately 935 megahertz. Testing was performed on a low-thrust torsion pendulum that is capable of detecting force at a single-digit micronewton level, within a stainless steel vacuum chamber with the door closed but at ambient atmospheric pressure. Several different test configurations were used, including two different test articles as well as a reversal of the test article orientation. In addition, the test article was replaced by an RF load to verify that the force was not being generated by effects not associated with the test article. The two test articles were designed by Cannae LLC of Doylestown, Pennsylvania. The torsion pendulum was designed, built, and operated by Eagleworks Laboratories at the NASA Johnson Space Center of Houston, Texas. Approximately six days of test integration were required, followed by two days of test operations, during which, technical issues were discovered and resolved. Integration of the two test articles and their supporting equipment was performed in an iterative fashion between the test bench and the vacuum chamber. In other words, the test article was tested on the bench, then moved to the chamber, then moved back as needed to resolve issues. Manual frequency control was required throughout the test. Thrust was observed on both test articles, even though one of the test articles was designed with the expectation that it would not produce thrust. Specifically, one test article contained internal physical modifications that were designed to produce thrust, while the other did not (with the latter being referred to as the "null" test article). Test data gathered includes torsion pendulum displacement measurements which are used to calculate generated force, still imagery in the visible spectrum to document the physical configuration, still imagery in the infrared spectrum to characterize the thermal environment, and video imagery. Post-test data includes static and animated graphics produced during RF resonant cavity characterization using the COMSOL Multiphysics software application. Excerpts from all of the above are included and discussed in this paper. Lessons learned from test integration and operations include identification of the need to replace manual control of the resonant cavity target frequency with an automated frequency control capability. Future test plans include the development of an automatic frequency control circuit. Test results indicate that the RF resonant cavity thruster design, which is unique as an electric propulsion device, is producing a force that is not attributable to any classical electromagnetic phenomenon and therefore is potentially demonstrating an interaction with the quantum vacuum virtual plasma. Future test plans include independent verification and validation at other test facilities
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Competing risks and deposit insurance governance convergence
Why do policies often seem to converge across countries at the same time? This question has been studied extensively in the diffusion literature. However, past research has not examined complex choice environments, especially where there are many alternatives. This article fills this gap in the literature. I show how Fine and Gray's Competing Risks Event History Analysis can be used to tease apart the causes of policy convergence. I apply the method to an examination of the reasons why, from the mid-1990s to 2007, many countries created independent deposit insurers. I find an interaction between international recommendations and regional peers' choices, particularly in the European Union. However, convergence appears to slow under the particular conditions of a banking crisis, regardless of how well independence is promoted. Possibly due to electoral incentives, democracies seem to have been more likely to create independent insurers. Ultimately, I demonstrate how competing risks analysis can help enable future research on policy choices, complementing methods previously applied in political economy. © The Author(s) 2013
The logic of tact:How decisions happen in situations of crisis
The mass-migration of refugees in the fall 2015 posed an immense humanitarian and logistical challenge: exhausted from their week-long journeys, refugees arrived in Vienna in need of care, shelter, food, medical aid, and onward transport. The refugee crisis was managed by an emerging polycentric and inter-sectoral collective of organizations. In this paper, we investigate how, during such a situation, leaders of these organizations made decisions in concert with each other and hence sustained the collective's capacity to act collectively. We ask: what was the logic of decision-making that orchestrated collective action during the crisis? In answering this question, we make the following contribution: departing from March's logics of consequences and appropriateness as well as Weick's work on sensemaking during crisis, we introduce an alternative logic that informed decision-making: the logic of tact. With this concept we (a) offer a better understanding of how managers make decisions under the condition of bounded rationality and the simultaneous transgression of their institutional identity in situations of crisis; and we (b) show that in decision-making under duress cognition is neither ahead of action, nor is action ahead of cognition; rather, tact explicates the rapid switching between cognition and action, orchestrating decision-making through this interplay
Long Spin Coherence and Relaxation Times in Nanodiamonds Milled from Polycrystalline C Diamond
The negatively charged nitrogen-vacancy centre (NV) in diamond has been
utilized in a wide variety of sensing applications. The centre's long spin
coherence and relaxation times (, and ) at room temperature
are crucial to this, as they often limit sensitivity. Using NV centres in
nanodiamonds allows for operations in environments inaccessible to bulk
diamond, such as intracellular sensing. We report long spin coherence and
relaxation times at room temperature for single NV centres in
isotopically-purified polycrystalline ball-milled nanodiamonds. Using a
spin-locking pulse sequence, we observe spin coherence times, , up 786
200 s. We also measure times up to 2.06 0.24 s
and times up to 4.32 0.60 ms. Scanning electron microscopy and
atomic force microscopy measurements show that the diamond containing the
NV centre with the longest time is smaller than 100 nm. EPR
measurements give an N concentration of 0.15 0.02 ppm for the
nanodiamond sample.Comment: 13 pages, 3 figure
Synthesis of Organosilicon Ligands for Europium (III) and Gadolinium (III) as Potential Imaging Agents
The relaxivity of MRI contrast agents can be increased by increasing the size of the contrast agent and by increasing concentration of the bound gadolinium. Large multi-site ligands able to coordinate several metal centres show increased relaxivity as a result. In this paper, an “aza-type Michael” reaction is used to prepare cyclen derivatives that can be attached to organosilicon frameworks via hydrosilylation reactions. A range of organosilicon frameworks were tested including silsesquioxane cages and dimethylsilylbenzene derivatives. Michael donors with strong electron withdrawing groups could be used to alkylate cyclen on three amine centres in a single step. Hydrosilylation successfully attached these to mono-, di-, and tri-dimethylsilyl-substituted benzene derivatives. The europium and gadolinium complexes were formed and studied using luminescence spectroscopy and relaxometry. This showed the complexes to contain two bound water moles per lanthanide centre and T1 relaxation time measurements demonstrated an increase in relaxivity had been achieved, in particular for the trisubstituted scaffold 1,3,5-tris((pentane-sDO3A)dimethylsilyl)benzene-Gd3. This showed a marked increase in the relaxivity (13.1 r1p/mM−1s−1)
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