259 research outputs found
Freire re-viewed
The work of Paulo Freire is associated with themes of oppression and liberation, and his critical pedagogy is visionary in its attempts to bring about social transformation. Freire has created a theory of education that embeds these issues within social relations that center around both ideological and material domination. In this review essay, Sue Jackson explores three books: Freire’s final work Pedagogy of Indignation; Cesar Augusto Rossatto’s Engaging Paulo Freire’s Pedagogy of Possibility, which attempts to engage Freire’s pedagogy of possibility; and C.A. Bowers and Frederique Apffel-Marglin’s edited collection Re-thinking Freire, which asks readers to reconsider Freire’s work in light of globalization and environmental crises. Jackson questions the extent to which Freire’s pedagogical approaches are useful to educators as well as to “the oppressed,” and whether challenges to re-think Freire can lead to new kinds of critical pedagogies
Applying modern interpretation techniques to old hydrocarbon fields to find new reserves: A case study in the onshore Gulf of Mexico, U.S.A.
This study shows how the use of modern geological investigative techniques can reopen old, “drained” hydrocarbon fields. Specifically, it looks at the White Castle Field in South Louisiana. This field has pay sections ranging from late Oligocene to late Miocene. The late Oligocene package is underexplored and understudied and contains 3 primary reservoirs (Cib Haz (CH), MW, and MR). This study established the depositional history of these reservoirs. During most of the late Oligocene, the White Castle Salt Dome was located in a minibasin on the continental slope. The CH and MW deposited in this minibasin. The CH is an amalgamation of slumped shelfal limestones, sandstones, and shales deposited during a lowstand systems tract (LST). The MW comprises a shelf-edge delta that is part of a LST. The MR is an incised valley fill located in the continental shelf that was deposited during LST after the minibasin was filled
Explosive diversification following a benthic to pelagic shift in freshwater fishes
BACKGROUND:
Interspecific divergence along a benthic to pelagic habitat axis is ubiquitous in freshwater fishes inhabiting lentic environments. In this study, we examined the influence of this habitat axis on the macroevolution of a diverse, lotic radiation using mtDNA and nDNA phylogenies for eastern North America\u27s most species-rich freshwater fish clade, the open posterior myodome (OPM) cyprinids. We used ancestral state reconstruction to identify the earliest benthic to pelagic transition in this group and generated fossil-calibrated estimates of when this shift occurred. This transition could have represented evolution into a novel adaptive zone, and therefore, we tested for a period of accelerated lineage accumulation after this historical habitat shift. RESULTS:
Ancestral state reconstructions inferred a similar and concordant region of our mtDNA and nDNA based gene trees as representing the shift from benthic to pelagic habitats in the OPM clade. Two independent tests conducted on each gene tree suggested an increased diversification rate after this inferred habitat transition. Furthermore, lineage through time analyses indicated rapid early cladogenesis in the clade arising after the benthic to pelagic shift. CONCLUSIONS:
A burst of diversification followed the earliest benthic to pelagic transition during the radiation of OPM cyprinids in eastern North America. As such, the benthic/pelagic habitat axis has likely influenced the generation of biodiversity across disparate freshwater ecosystems.
doi: 10.1186/1471-2148-13-27
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The short-chain fatty acid acetate reduces appetite via a central homeostatic mechanism
Increased intake of dietary carbohydrate that is fermented in the colon by the microbiota has been reported to decrease body weight, although the mechanism remains unclear. Here we use in vivo11C-acetate and PET-CT scanning to show that colonic acetate crosses the blood–brain barrier and is taken up by the brain. Intraperitoneal acetate results in appetite suppression and hypothalamic neuronal activation patterning. We also show that acetate administration is associated with activation of acetyl-CoA carboxylase and changes in the expression profiles of regulatory neuropeptides that favour appetite suppression. Furthermore, we demonstrate through 13C high-resolution magic-angle-spinning that 13C acetate from fermentation of 13C-labelled carbohydrate in the colon increases hypothalamic 13C acetate above baseline levels. Hypothalamic 13C acetate regionally increases the 13C labelling of the glutamate–glutamine and GABA neuroglial cycles, with hypothalamic 13C lactate reaching higher levels than the ‘remaining brain’. These observations suggest that acetate has a direct role in central appetite regulation
Considerations of Efficiency and Distributive Justice in Multidimensional Poverty Measurement
Ab den 1980er Jahren entwickelte Amartya Sen eine neue Wohlfahrtstheorie: den Capability Approach (Sen, 1979; 1985; 1992; 1999; 2009). Dabei ersetzen Capabilities und Functionings, d.h. das, was Personen tatsächlich in der Lage sind zu tun und zu sein, den traditionellen Einkommensansatz. Armut ist im Capability Approach das Unvermögen, ein bestimmtes Minimum an zentralen Capabilities zu erreichen, die benötigt werden, um das Leben nach den eigenen Vorstellungen zu gestalten.
Der Capability Approach hat so viele interessante Eigenschaften, besonders in Bezug auf die Armutsmessung, dass er zunehmend Einfluss in der Wohlfahrtsökonomie gewinnt. Diese Entwicklung wird durch empirische Untersuchungen gefördert, die zeigen, dass dieser multidimensionale Ansatz zur Armutsmessung deutlich andere Ergebnisse generiert als der traditionelle Einkommensansatz (vgl. Klasen, 2000, Alkire und Santos, 2010, Figari, 2012).
Der derzeitige multidimensionale Ansatz hat jedoch eine methodische Schwäche: Ungleichheit zwischen Armutsdimensionen wird entweder als Korrelationssensitivität definiert – womit Effizienz aber nicht Verteilungsgerechtigkeit berücksichtigt wird – oder als die Verteilung multipler Mangelerscheinungen in einer Gesellschaft – womit Verteilungsgerechtigkeit aber nicht Effizienz berücksichtigt wird.
Die ersten beiden Kapitel dieser Dissertation widmen sich der Behebung dieser methodischen Schwäche. Dazu wird Ungleichheit zwischen Dimensionen zunächst als „korrelationssensitive Verteilung multipler Mangelerscheinungen in einer Gesellschaft“ definiert. Die ersten beiden Kapitel operationalisieren diese erweiterte Definition für den Fall ordinaler und kardinaler Armutsindices. Im Einzelnen wird ein neues Axiom für den ordinalen sowie den kardinalen Fall eingeführt, das das Ausmaß, mit dem ein Ungleichheitsfördernder Tausch Armut sinken (oder steigen) lässt, von der Beziehung zwischen den Armutsdimensionen abhängig macht. Diese Neuerung wird benutzt um eine neue Klasse ordinaler bzw. kardinaler Armutsindices herzuleiten. Diese zwei Klassen sind die ersten additiven Armutsindices die in der Lage sind, sowohl Ungleichheit als auch Korrelationssensitivität zu erfassen.
Das dritte Kapitel nutzt das deutsche sozio-ökonomische Panel um zwei ordinale Armutsindices für Deutschland vorzuschlagen, die auf der zuvor entwickelten Methode basieren: den „Deutschen Korrelationssensitiven Armutsindex“ und den „Subjektiven Korrelationssensitiven Armutsindex“. Die beiden Indices werden mit dem offiziellen deutschen Armutsmaß, der Armutsgefährdungsquote, über Dimensionen, Regionen und über die Zeit hinweg verglichen. Die Resultate zeigen vor allem eines: die signifikanten Unterschiede in der Beurteilung von Armut und Armutstrends die durch die verschiedenen Indices versursacht werden und den hohen Mehrwert den die Operationalisierung des Capability Approachs darstellt
Status of the Nif Power Conditioning System
The NIF Power Conditioning System provides the pulsed excitation required to drive flashlamps in the laser's optical amplifiers. Modular in design, each of the 192 Main Energy Storage Modules (MESMs) storage up to 2.2 MJ of electrical energy in its capacitor bank before delivering the energy to 20 pairs of flashlamps in a 400 {micro}s pulse (10% power points). The peak current of each MESM discharge is 0.5 MA. Production, installation, commissioning and operation of the NIF Power Conditioning continue to progress rapidly, with the goals of completing accelerated production in late 2007 and finishing commissioning by early 2008, all the while maintaining an aggressive operations schedule. To date, more than 80% of the required modules have been assembled, shipped and installed in the facility, representing more that 240 MJ of stored energy available for driving NIF flashlamps. The MESMs have displayed outstanding reliability during daily, multiple-shift operations
A Comparison of the Electrochemical Behavior of Carbon Aerogels and Activated Carbon Fiber Cloths
Electrochemical capacitative behavior of carbon aerogels and commercial carbon fiber cloths was studied in 5M KOH, 3M sulfuric acid, and 0.5M tetrethylammonium tetrafluoroborate/propylene carbonate electrolytes. The resorcinol-formaldehyde based carbon aerogels with a range of denisty (0.2-0.85 g/cc) have open-cell structures with ultrafine pore sizes (5-50 nm), high surface area (400-700 m{sup 2}/g), and a solid matrix composed of interconnected particles or fibers with characteristic diameters of 10 nm. The commercial fiber cloths in the density range 0.2-04g/cc have high surface areas (1000-2500 m{sup 2}/g). The volumetric capacitances of high-density aerogels are shown to be comparable to or exceeding those from activated carbon fibers. Electrochemical behavior of these materials in various electrolytes is compared and related to their physical properties
Spatial Geographic Mosaic in an Aquatic Predator-Prey Network
The geographic mosaic theory of coevolution predicts 1) spatial variation in predatory structures as well as prey defensive traits, and 2) trait matching in some areas and trait mismatching in others mediated by gene flow. We examined gene flow and documented spatial variation in crushing resistance in the freshwater snails Mexipyrgus churinceanus, Mexithauma quadripaludium, Nymphophilus minckleyi, and its relationship to the relative frequency of the crushing morphotype in the trophically polymorphic fish Herichthys minckleyi. Crushing resistance and the frequency of the crushing morphotype did show spatial variation among 11 naturally replicated communities in the Cuatro Ciénegas valley in Mexico where these species are all endemic. The variation in crushing resistance among populations was not explained by geographic proximity or by genetic similarity in any species. We detected clear phylogeographic patterns and limited gene flow for the snails but not for the fish. Gene flow among snail populations in Cuatro Ciénegas could explain the mosaic of local divergence in shell strength and be preventing the fixation of the crushing morphotype in Herichthys minckleyi. Finally, consistent with trait matching across the mosaic, the frequency of the fish morphotype was negatively correlated with shell crushing resistance likely reflecting the relative disadvantage of the crushing morphotype in communities where the snails exhibit relatively high crushing resistance
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An Update on the Status of the NIF Power Conditioning System
The National Ignition Facility (NIF) Power Conditioning System provides the pulsed excitation required to drive flashlamps in the laser's optical amplifiers. Modular in design, each of the 192 Main Energy Storage Modules (MESMs) stores up to 2.2 MJ of electrical energy in its capacitor bank before delivering the energy to 20 pairs of flashlamps in a 400 {micro}s pulse (10% power points). The peak current of each MESM discharge is 0.5 MA. Production, installation, commissioning and operation of the NIF Power Conditioning continue to progress rapidly, with the goals of completing accelerated production and commissioning by early 2008, while maintaining an aggressive operation schedule. To date, more than 97% of the required modules have been assembled, shipped and installed in the facility, representing more that 380 MJ of stored energy available for driving NIF flashlamps. The MESMs have displayed outstanding reliability during daily, multiple-shift operations
Width of buccal and posterior corridors: differences between cases treated with asymmetric and symmetric extractions
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