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Search Results: 1 - 10 of 299226 matches for " Ralph J. Greenspan "
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The Drosophila foraging Gene Mediates Adult Plasticity and Gene–Environment Interactions in Behaviour, Metabolites, and Gene Expression in Response to Food Deprivation
Clement F. Kent,Tim Daskalchuk,Lisa Cook,Marla B. Sokolowski ,Ralph J. Greenspan
PLOS Genetics , 2009, DOI: 10.1371/journal.pgen.1000609
Abstract: Nutrition is known to interact with genotype in human metabolic syndromes, obesity, and diabetes, and also in Drosophila metabolism. Plasticity in metabolic responses, such as changes in body fat or blood sugar in response to changes in dietary alterations, may also be affected by genotype. Here we show that variants of the foraging (for) gene in Drosophila melanogaster affect the response to food deprivation in a large suite of adult phenotypes by measuring gene by environment interactions (GEI) in a suite of food-related traits. for affects body fat, carbohydrates, food-leaving behavior, metabolite, and gene expression levels in response to food deprivation. This results in broad patterns of metabolic, genomic, and behavioral gene by environment interactions (GEI), in part by interaction with the insulin signaling pathway. Our results show that a single gene that varies in nature can have far reaching effects on behavior and metabolism by acting through multiple other genes and pathways.
Genes Involved in Sex Pheromone Discrimination in Drosophila melanogaster and Their Background-Dependent Effect
Benjamin Houot, Stéphane Fraichard, Ralph J. Greenspan, Jean-Fran?ois Ferveur
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0030799
Abstract: Mate choice is based on the comparison of the sensory quality of potential mating partners, and sex pheromones play an important role in this process. In Drosophila melanogaster, contact pheromones differ between male and female in their content and in their effects on male courtship, both inhibitory and stimulatory. To investigate the genetic basis of sex pheromone discrimination, we experimentally selected males showing either a higher or lower ability to discriminate sex pheromones over 20 generations. This experimental selection was carried out in parallel on two different genetic backgrounds: wild-type and desat1 mutant, in which parental males showed high and low sex pheromone discrimination ability respectively. Male perception of male and female pheromones was separately affected during the process of selection. A comparison of transcriptomic activity between high and low discrimination lines revealed genes not only that varied according to the starting genetic background, but varied reciprocally. Mutants in two of these genes, Shaker and quick-to-court, were capable of producing similar effects on discrimination on their own, in some instances mimicking the selected lines, in others not. This suggests that discrimination of sex pheromones depends on genes whose activity is sensitive to genetic context and provides a rare, genetically defined example of the phenomenon known as “allele flips,” in which interactions have reciprocal effects on different genetic backgrounds.
Self-Sustaining Thorium Boiling Water Reactors
Francesco Ganda,Francisco J. Arias,Jasmina Vujic,Ehud Greenspan
Sustainability , 2012, DOI: 10.3390/su4102472
Abstract: A thorium-fueled water-cooled reactor core design approach that features a radially uniform composition of fuel rods in stationary fuel assembly and is fuel-self-sustaining is described. This core design concept is similar to the Reduced moderation Boiling Water Reactor (RBWR) proposed by Hitachi to fit within an ABWR pressure vessel, with the following exceptions: use of thorium instead of depleted uranium for the fertile fuel; elimination of the internal blanket; and elimination of absorbers from the axial reflectors, while increasing the length of the fissile zone. The preliminary analysis indicates that it is feasible to design such cores to be fuel-self-sustaining and to have a comfortably low peak linear heat generation rate when operating at the nominal ABWR power level of nearly 4000 MWth. However, the void reactivity feedback tends to be too negative, making it difficult to have sufficient shutdown reactivity margin at cold zero power condition. An addition of a small amount of plutonium from LWR used nuclear fuel was found effective in reducing the magnitude of the negative void reactivity effect and enables attaining adequate shutdown reactivity margin; it also flattens the axial power distribution. The resulting design concept offers an efficient incineration of the LWR generated plutonium in addition to effective utilization of thorium. Additional R&D is required in order to arrive at a reliable practical and safe design.
Oral lesions in infection with human immunodeficiency virus
Coogan,Maeve M.; Greenspan,John; Challacombe,Stephen J.;
Bulletin of the World Health Organization , 2005, DOI: 10.1590/S0042-96862005000900016
Abstract: this paper discusses the importance of oral lesions as indicators of infection with human immunodeficiency virus (hiv) and as predictors of progression of hiv disease to acquired immunodeficiency syndrome (aids). oral manifestations are among the earliest and most important indicators of infection with hiv. seven cardinal lesions, oral candidiasis, hairy leukoplakia, kaposi sarcoma, linear gingival erythema, necrotizing ulcerative gingivitis, necrotizing ulcerative periodontitis and non-hodgkin lymphoma, which are strongly associated with hiv infection, have been identified and internationally calibrated, and are seen in both developed and developing countries. they may provide a strong indication of hiv infection and be present in the majority of hiv-infected people. antiretroviral therapy may affect the prevalence of hiv-related lesions. the presence of oral lesions can have a significant impact on health-related quality of life. oral health is strongly associated with physical and mental health and there are significant increases in oral health needs in people with hiv infection, especially in children, and in adults particularly in relation to periodontal diseases. international collaboration is needed to ensure that oral aspects of hiv disease are taken into account in medical programmes and to integrate oral health care with the general care of the patient. it is important that all health care workers receive education and training on the relevance of oral health needs and the use of oral lesions as surrogate markers in hiv infection.
A Phased Development of Breed-and-Burn Reactors for Enhanced Nuclear Energy Sustainability
Ehud Greenspan
Sustainability , 2012, DOI: 10.3390/su4102745
Abstract: Several options for designing fast reactors to operate in the Breed-and-Burn (B&B) mode are compared and a strategy is outlined for early introduction of B&B reactors followed by a gradual increase in the fuel utilization of such reactors. In the first phase the fast reactor core will consist of a subcritical B&B blanket driven by a relatively small critical seed. As the required discharge burnup/radiation-damage to both driver and blanket fuel had already been proven, and as the depleted uranium fueled B&B blanket could generate close to 2/3 of the core power and will have very low fuel cycle cost, the deployment of such fast reactors could start in the near future. The second phase consists of deploying self-sustaining stationary wave B&B reactors. It will require development of fuel technology that could withstand peak burnups of ~30% and peak radiation damage to the cladding of ~550 dpa. The third phase requires development of a fuel reconditioning technology that will enable using the fuel up to an average burnup of ~50%—the upper bound permitted by neutron balance considerations when most of the fission products are not separated from the fuel. The increase in the uranium ore utilization relative to that provided by contemporary power reactors is estimated to be 20, 40 and 100 folds for, respectively, phase 1, 2 and 3. The energy value of the depleted uranium stockpiles (“waste”) accumulated in the US is equivalent to, when used in the B&B reactors, up to 20 centuries of the total 2010 USA supply of electricity. Therefore, a successful development of B&B reactors could provide a great measure of energy sustainability and cost stability.
LA CRISIS
Greenspan,Alan;
Revista de Economía Institucional , 2010,
Abstract: this article reviews the causes of the crisis, explores the nature of financial intermediation, presents a set of reforms to overcome the deficiencies of the regulatory structure and examines the role of monetary policy in the current crisis. it concludes that it is essential to increase regulatory capital requirements and liquidity of banks and increase the guarantees of financial products that are traded globally.
La crisis
Alan Greenspan
Revista de Economía Institucional , 2010,
Abstract: Este artículo revisa las causas de la crisis, explora la naturaleza de la intermediación financiera, presenta un conjunto de reformas para superar las deficiencias de la estructura reguladora y examina el papel de la política monetaria en la crisis actual. Concluye que es primordial aumentar los requerimientos regulatorios de capital y de liquidez de los bancos e incrementar en forma significativa las garantías obligatorias de los productos financieros que se negocian globalmente.
The Power of Spectacle
Anna Greenspan
Culture Unbound : Journal of Current Cultural Research , 2012,
Abstract: When people say Shanghai looks like the future the setting is almost always the same. Evening descends and the skyscrapers clustered on the eastern shore of the Huangpu light up. Super towers are transformed into giant screens. The spectacular skyline, all neon and lasers and LED, looms as a science fiction backdrop. Staring out from the Bund, across to Pudong, one senses the reemergence of what JG Ballard once described as an ”electric and lurid city, more exciting than any other in the world.” The high-speed development of Pudong – in particular the financial district of Lujiazui – is the symbol of contemporary Shanghai and of China’s miraculous rise.Yet, Pudong is also taken as a sign of much that is wrong with China’s new urbanism. To critics the sci-fi skyline is an emblem of the city’s shallowness, which focuses all attention on its glossy facade. Many share the sentiment of free market economist Milton Friedman who, when visiting Pudong famously derided the brand new spectacle as a giant Potemkin village. Nothing but “the statist monument for a dead pharaoh,” he is quoted as saying.This article explores Pudong in order to investigate the way spectacle functions in China’s most dynamic metropolis. It argues that the skeptical hostility towards spectacle is rooted in the particularities of a Western philosophical tradition that insists on penetrating the surface, associating falsity with darkness and truth with light.In contrast, China has long recognized the power of spectacle (most famously inventing gunpowder but using it only for fireworks). Alongside this comes an acceptance of a shadowy world that belongs to the dark. This acknowledgment of both darkness and light found in traditional Chinese culture (expressed by the constant revolutions of the yin/yang symbol) may provide an alternative method for thinking about the tension between the spectacular visions of planners and the unexpected and shadowy disruptions from the street.
Sacrifice and Commitment: American Volunteers in the Spanish Civil War
Anders Greenspan
Journal of Arts and Humanities , 2013,
Abstract: The Spanish Civil War (1936-1939) was the last European war before the start of World War II. The war, an ideological struggle between Francisco Franco and his nationalist supporters, aided by the Germans and Italians, sought to remove from power the Spanish Republic, which was aided by the Soviet Union. On both sides of the conflict were volunteers from many countries, including the United States of America. American volunteers fought on both sides of the war, yet more chose the side of the Republicans. Many, but not all, were motivated by political beliefs. Others wanted the perceived romance and excitement of battle, or the sense that they were being of help. The volunteers discussed in this study came from all of these categories, with the ones having political motivation the largest group. They detailed their experiences and their views of the war to their friends, families and comrades back home in the United States. These letters, which come from the Abraham Lincoln Brigade Archives at New York University, form the main part of the study and provide a deeper insight into what these men and women were thinking, as well as providing insight into their desire to fight in Spain. Through their eyes it is possible to gain a deeper understanding of their experiences and their motivations. For many of them, their experiences in Spain formed an important part of their journey in life. Some of them remained loyal to the Communist ideology throughout their lives, while others changed their views as the ruthlessness of Stalin became better known. A modern audience can benefit from a chance to read their thoughts and ideas in an attempt to better understand the events that helped drive the world into the Second World War.
The Catalan simplicial set and uniform classification of monoidal-type categories
Aaron Greenspan
Mathematics , 2015,
Abstract: Many monoidal-type objects are known to be classified by maps from the Catalan simplicial set $\mathbb{C}$ to various nerves of categories and higher categories. There are, for example, three different nerves of the 2-category of categories $\mathsf{Cat}$ with the property that maps from $\mathbb{C}$ into them are in one to one correspondence with strict monoidal, monoidal, and skew monoidal categories. In this last case, the classification result can be understood as justifying the definition of skew monoidal categories intrinsically in terms of the structure of $\mathbb{C}$. In this paper, we consider a single nerve -- the homotopy coherent nerve of $\mathsf{Cat}$ viewed as a one object simplicially enriched category -- and verify that maps from $\mathbb{C}$ to it classify the three monoidal-type categories mentioned above, as well as lax monoidal categories and $\Sigma$-monoidal categories. Furthermore, we identify a new monoidal-type category corresponding to the most general such maps and present them in the usual way: a collection of data subject to explicit coherence requirements. These results suggest that the space of maps from $\mathbb{C}$ to the coherent nerve of $\mathsf{Cat}$ provides a uniform framework for the definition and study of many species of monoidal-type category, old or new.
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