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Sample records for argentine reactor ra-6

  1. Contemporary Argentine Cinema during Neoliberalism

    ERIC Educational Resources Information Center

    Rocha, Carolina

    2009-01-01

    In this article I analyze contemporary Argentine cinematic production assessing the impact of Law 24,377 that was implemented in 1995 and that provided much-needed funds for national productions. By looking at film production and consumption, the emergence of young filmmakers and the performance of both commercial films and those belonging to the…

  2. Selection of the Argentine indicator region

    NASA Technical Reports Server (NTRS)

    Ramirez, C. J.; Reed, C. R. (Principal Investigator)

    1982-01-01

    Determined from available Argentine crop statistics, selection of the Indicator Region was based on the highest wheat, corn, and soybean producing provinces, which were: Buenos Aires, Cordoba, Entre Rios, and Santa Fe. Each province in Argentina was examined for the availability of LANDSAT data; area, yield and production statistics; crop calendars; and other ancillary data. The Argentine Indicator Region is described.

  3. Trap-mulching Argentine ants.

    PubMed

    Silverman, Jules; Sorenson, Clyde E; Waldvogel, Michael G

    2006-10-01

    Argentine ant, Linepithema humile (Mayr), management is constrained, in large part, by polydomy where nestmates are distributed extensively across urban landscapes, particularly within mulch. Management with trap-mulching is a novel approach derived from trap-cropping where ants are repelled from a broad domain of nest sites to smaller defined areas, which are subsequently treated with insecticide. This concept was field-tested with mulch surrounding ornamental trees replaced with a narrow band of pine (Pinus spp.) needle mulch (trap) within a much larger patch of repellent aromatic cedar (Juniperus spp.) mulch. After ants reestablished around the trees, the pine needle mulch band was treated with 0.06% fipronil (Termidor). Poor results were obtained when the trap extended from the tree trunk to the edge of the mulched area. When the trap was applied as a circular band around the tree trunk reductions in the number of foraging ants were recorded through 14 d compared with an untreated mulch control, but not for longer periods. Reductions in the number of ant nests within mulch were no different between the trap mulch and any of the other treatments. We conclude that trap-mulching offers limited benefits, and that successful management of Argentine ants will require implementation of complementary or perhaps alternative strategies. PMID:17066809

  4. [Theory of Argentine cultural "isoidia"].

    PubMed

    Pagés Larraya, F

    1982-03-01

    For the epidemiological study of mental pathology in the Argentine Republic the country has been systematically divided into 25 Cultural Areas, to which it is necessary to add the "megalopolis" of Buenos Aires City and conurbation. Each one of these Cultural Areas is analysed according to the anthropological method, which enables us to comprise an innumerable series of epidemiological variants. We investigate, for example, in every one of them the situation of the mentally sick within the community and the cultural attitude of the latter towards mental illness. For statistical purposes of Psychiatrical Epidemiology an experimental study of the prevalence of this type of disease is carried out in each of the above mentioned areas. As a complement to this investigation an analysis of the Institutional Prevalence of Mental Pathology has been performed, i.e., of the patients attended at the State Establishments, be they national, provincial or municipal. PMID:7136824

  5. [Potential emigration of young Italian-Argentines].

    PubMed

    Cacopardo, M C

    1992-12-01

    The author examines trends in out-migration among young, highly skilled Argentines, with a focus on those of Italian descent. Data are from interviews conducted among young adults in Buenos Aires, Mar del Plata, and Rosario. Major factors influencing migration include perceived labor force and economic opportunities. (SUMMARY IN ENG) PMID:12344794

  6. Radiation Studies with Argentine Ion Exchange Material

    SciTech Connect

    Crawford, C.L.

    2002-06-28

    A recent technology exchange between Argentina Nuclear Energy Commission (CNEA) and the US Department of Energy involved vitrification studies of ion exchange resins. Details of the spent ion exchange resins currently stored at two Argentine nuclear power plants, Atucha I and Embalse, have been presented in earlier reports. The present study examines irradiation of simulant samples of ion exchange resins.

  7. SAC-B, Argentine scientific satellite

    NASA Technical Reports Server (NTRS)

    Gulich, J. M.; White, C.

    1994-01-01

    The project and the missions of the Argentine scientific satellite, SAC-B, are summarized. SAC-B is an international cooperative project between NASA and the Secretariat of State of Science and Technology of the Argentine Republic. The objective of SAC-B is to advance the study of solar physics and astrophysics through the examination of solar flares, gamma ray burst sources and the diffuse soft X-ray cosmic background. The scientific payload comprises an instrument to measure the temporal evolution of X-ray emissions from solar flares as well as nonsolar gamma ray bursts, a combined soft X-ray and gamma ray burst detector, a diffuse X-ray background detector, and an energetic neutral atoms detector.

  8. Where and how Argentine ant (Linepithema humile) spreads in Corsica?

    PubMed

    Blight, Olivier; Orgeas, Jérôme; Renucci, Marielle; Tirard, Alain; Provost, Erick

    2009-08-01

    The Argentine ant, Linepithema humile (Dolichoderinae), is one of the most widespread invasive ant species in the world. When established in optimal habitat, this species usually excludes most other local ants and can heavily impact other arthropods as well. Although Argentine ants have been present in southern Europe for more than 100 years, they were first noted in Corsica, a French Mediterranean island, in 1957 in only one urban station. In this study, we aimed to map precisely their geographical distribution in Corsica and to quantify their presence by using an infestation index. We recorded changes in the distribution of Argentine ants in Corsica over the past decade. Argentine ants appeared to be well established within their introduced range and spreading along the Corsican coasts principally through Human-mediated jump-dispersal but not homogenously. PMID:19632658

  9. Pheromone disruption of Argentine ant trail integrity

    USGS Publications Warehouse

    Suckling, D.M.; Peck, R.W.; Manning, L.M.; Stringer, L.D.; Cappadonna, J.; El-Sayed, A. M.

    2008-01-01

    Disruption of Argentine ant trail following and reduced ability to forage (measured by bait location success) was achieved after presentation of an oversupply of trail pheromone, (Z)-9-hexadecenal. Experiments tested single pheromone point sources and dispersion of a formulation in small field plots. Ant walking behavior was recorded and digitized by using video tracking, before and after presentation of trail pheromone. Ants showed changes in three parameters within seconds of treatment: (1) Ants on trails normally showed a unimodal frequency distribution of walking track angles, but this pattern disappeared after presentation of the trail pheromone; (2) ants showed initial high trail integrity on a range of untreated substrates from painted walls to wooden or concrete floors, but this was significantly reduced following presentation of a point source of pheromone; (3) the number of ants in the pheromone-treated area increased over time, as recruitment apparently exceeded departures. To test trail disruption in small outdoor plots, the trail pheromone was formulated with carnuba wax-coated quartz laboratory sand (1 g quartz sand/0.2 g wax/1 mg pheromone). The pheromone formulation, with a half-life of 30 h, was applied by rotary spreader at four rates (0, 2.5, 7.5, and 25 mg pheromone/m2) to 1- and 4-m2 plots in Volcanoes National Park, Hawaii. Ant counts at bait cards in treated plots were significantly reduced compared to controls on the day of treatment, and there was a significant reduction in ant foraging for 2 days. These results show that trail pheromone disruption of Argentine ants is possible, but a much more durable formulation is needed before nest-level impacts can be expected. ?? 2008 Springer Science+Business Media, LLC.

  10. Pheromone disruption of Argentine ant trail integrity.

    PubMed

    Suckling, D M; Peck, R W; Manning, L M; Stringer, L D; Cappadonna, J; El-Sayed, A M

    2008-12-01

    Disruption of Argentine ant trail following and reduced ability to forage (measured by bait location success) was achieved after presentation of an oversupply of trail pheromone, (Z)-9-hexadecenal. Experiments tested single pheromone point sources and dispersion of a formulation in small field plots. Ant walking behavior was recorded and digitized by using video tracking, before and after presentation of trail pheromone. Ants showed changes in three parameters within seconds of treatment: (1) Ants on trails normally showed a unimodal frequency distribution of walking track angles, but this pattern disappeared after presentation of the trail pheromone; (2) ants showed initial high trail integrity on a range of untreated substrates from painted walls to wooden or concrete floors, but this was significantly reduced following presentation of a point source of pheromone; (3) the number of ants in the pheromone-treated area increased over time, as recruitment apparently exceeded departures. To test trail disruption in small outdoor plots, the trail pheromone was formulated with carnuba wax-coated quartz laboratory sand (1 g quartz sand/0.2 g wax/1 mg pheromone). The pheromone formulation, with a half-life of 30 h, was applied by rotary spreader at four rates (0, 2.5, 7.5, and 25 mg pheromone/m(2)) to 1- and 4-m(2) plots in Volcanoes National Park, Hawaii. Ant counts at bait cards in treated plots were significantly reduced compared to controls on the day of treatment, and there was a significant reduction in ant foraging for 2 days. These results show that trail pheromone disruption of Argentine ants is possible, but a much more durable formulation is needed before nest-level impacts can be expected. PMID:19034574

  11. Carbohydrate supply limits invasion of natural communities by Argentine ants.

    PubMed

    Rowles, Alexei D; Silverman, Jules

    2009-08-01

    The ability of species to invade new habitats is often limited by various biotic and physical factors or interactions between the two. Invasive ants, frequently associated with human activities, flourish in disturbed urban and agricultural environments. However, their ability to invade and establish in natural habitats is more variable. This is particularly so for the invasive Argentine ant (Linepithema humile). While biotic resistance and low soil moisture limits their invasion of natural habitats in some instances, the effect of food availability has been poorly explored. We conducted field experiments to determine if resource availability limits the spread and persistence of Argentine ants in remnant natural forest in North Carolina. Replicated transects paired with and without sucrose solution feeding stations were run from invaded urban edges into forest remnants and compared over time using baits and direct counts at feeding stations. Repeated under different timing regimes in 2006 and 2007, access to sucrose increased local Argentine ant abundances (1.6-2.5 fold) and facilitated their progression into the forest up to 73 +/- 21% of 50-m transects. Resource removal caused an expected decrease in Argentine ant densities in 2006, in conjunction with their retreat to the urban/forest boundary. However, in 2007, Argentine ant numbers unexpectedly continued to increase in the absence of sugar stations, possibly through access to alternative resources or conditions not available the previous year such as honeydew-excreting Hemiptera. Our results showed that supplementing carbohydrate supply facilitates invasion of natural habitat by Argentine ants. This is particularly evident where Argentine ants continued to thrive following sugar station removal. PMID:19452171

  12. Detrimental effects of highly efficient interference competition: invasive Argentine ants outcompete native ants at toxic baits.

    PubMed

    Buczkowski, Grzegorz; Bennett, Gary W

    2008-06-01

    The Argentine ant (Linepithema humile) is an invasive species that disrupts the balance of natural ecosystems by displacing indigenous ant species throughout its introduced range. Previous studies that examined the mechanisms by which Argentine ants attain ecological dominance showed that superior interference and exploitation competition are key to the successful displacement of native ant species. The objective of this research was to test the hypothesis that effective interference competition by Argentine ants may also be detrimental to the survival of Argentine ant colonies where Argentine ants and native ants compete at toxic baits used to slow the spread of Argentine ants. To study this hypothesis, we examined the competitive interactions between Argentine ants and native odorous house ants, Tapinoma sessile, in the presence and absence of toxic baits. Results showed that Argentine ants aggressively outcompete T. sessile from toxic baits through efficient interference competition and monopolize bait resources. This has severe negative consequences for the survival of Argentine ants as colonies succumb to the toxic effects of the bait. In turn, T. sessile avoid areas occupied by Argentine ants, give up baits, and consequently suffer minimal mortality. Our results provide experimental evidence that highly efficient interference competition may have negative consequences for Argentine ants in areas where toxic baits are used and may provide a basis for designing innovative management programs for Argentine ants. Such programs would have the double benefit of selectively eliminating the invasive species while simultaneously protecting native ants from the toxic effects of baits. PMID:18559180

  13. [The Argentine Health System: organization and financial features].

    PubMed

    Arce, Hugo E

    2012-01-01

    The Argentine health system is defined by the following features: a) federal country organization; b) coexistence of public and private services with either outpatients or inpatients; c) fragmented entities of social security, most of these originated outside of the state organization. Components of the system are described and weighed; making decisions strength between national and provincial health authorities is analyzed and the Argentine system is compared with that of other countries. Statistical data on distribution of health expenditures and coverage of health services are presented as well as financial flow among diverse funding sources, insurers, providers and users of each sector. PMID:23089118

  14. REACTOR

    DOEpatents

    Szilard, L.

    1963-09-10

    A breeder reactor is described, including a mass of fissionable material that is less than critical with respect to unmoderated neutrons and greater than critical with respect to neutrons of average energies substantially greater than thermal, a coolant selected from sodium or sodium--potassium alloys, a control liquid selected from lead or lead--bismuth alloys, and means for varying the quantity of control liquid in the reactor. (AEC)

  15. REACTOR

    DOEpatents

    Christy, R.F.

    1961-07-25

    A means is described for co-relating the essential physical requirements of a fission chain reaction in order that practical, compact, and easily controllable reactors can be built. These objects are obtained by employing a composition of fissionsble isotope and moderator in fluid form in which the amount of fissionsble isotcpe present governs the reaction. The size of the reactor is no longer a critical factor, the new criterion being the concentration of the fissionable isotope.

  16. REACTOR

    DOEpatents

    Roman, W.G.

    1961-06-27

    A pressurized water reactor in which automatic control is achieved by varying the average density of the liquid moderator-cooiant is patented. Density is controlled by the temperature and power level of the reactor ftself. This control can be effected by the use of either plate, pellet, or tubular fuel elements. The fuel elements are disposed between upper and lower coolant plenum chambers and are designed to permit unrestricted coolant flow. The control chamber has an inlet opening communicating with the lower coolant plenum chamber and a restricted vapor vent communicating with the upper coolant plenum chamber. Thus, a variation in temperature of the fuel elements will cause a variation in the average moderator density in the chamber which directly affects the power level of the reactor.

  17. Different Argentine Rural Extensionists' Mindsets and Their Practical Implications

    ERIC Educational Resources Information Center

    Landini, Fernando

    2015-01-01

    Purpose: This paper reflects upon the practice of Argentine rural extensionists working in the extension public system through the process of identifying different rural extensionists' types of mindsets and comparing them with transfer of technology extension approach, dialogical processes of horizontal knowledge exchange, participatory…

  18. The Mindful Attention Awareness Scale (MAAS) in an Argentine Population

    ERIC Educational Resources Information Center

    Montes, Silvana Andrea; Ledesma, Rubén Daniel; García, Natalia Mariana; Poó, Fernando Martín

    2014-01-01

    The purpose of this study was to provide evidence of validity for the Mindful Attention Awareness Scale scores in an Argentine sample (Spanish-language version). Results indicated satisfactory psychometric properties (a one-factor structure, good item discrimination, high reliability, and significant correlations with additional measures). This…

  19. REACTORS

    DOEpatents

    Spitzer, L. Jr.

    1961-10-01

    Thermonuclear reactors, methods, and apparatus are described for controlling and confining high temperature plasma. Main axial confining coils in combination with helical windings provide a rotational transform that avoids the necessity of a figure-eight shaped reactor tube. The helical windings provide a multipolar helical magnetic field transverse to the axis of the main axial confining coils so as to improve the effectiveness of the confining field by counteracting the tendency of the more central lines of force in the stellarator tube to exchange positions with the magnetic lines of force nearer the walls of the tube. (AEC)

  20. The Argentine ant persists through unfavorable winters via a mutualism facilitated by a native tree.

    PubMed

    Brightwell, Robert J; Silverman, Jules

    2011-10-01

    Mutualisms and facilitations can fundamentally change the relationship between an organism's realized and fundamental niche. Invasive species may prove particularly suitable models for investigating this relationship as many are dependent on finding new partners for successful establishment. We conducted field-based experiments testing whether a native tree facilitates the successful survival of the invasive Argentine ant, Linepithema humile (Mayr), through unfavorable winter conditions in the southeastern United States. We found Argentine ant nests aggregated around the native loblolly pine, Pinus taeda L., during the winter months. The bark of this tree absorbed enough radiant solar energy to reach temperatures suitable for Argentine ant foraging even when ambient temperatures should have curtailed all foraging. Conversely, foraging ceased when the trunk was shaded. The sun-warmed bark of this tree gave the Argentine ant access to a stable honeydew resource. Argentine ants were not found on or near deciduous trees even though bark temperatures were warm enough to permit Argentine ant foraging on cold winter days. Augmenting deciduous trees with sucrose water through the winter months lead to Argentine ant nests remaining at their base and Argentine ants foraging on the tree. The Argentine ant requires both foraging opportunity and a reliable winter food source to survive through unfavorable winter conditions in the southeastern United States. The loblolly pine provided both of these requirements extending the realized niche of Argentine ants beyond its fundamental niche. PMID:22251714

  1. REACTOR

    DOEpatents

    Spitzer, L. Jr.

    1962-01-01

    The system conteraplates ohmically heating a gas to high temperatures such as are useful in thermonuclear reactors of the stellarator class. To this end the gas is ionized and an electric current is applied to the ionized gas ohmically to heat the gas while the ionized gas is confined to a central portion of a reaction chamber. Additionally, means are provided for pumping impurities from the gas and for further heating the gas. (AEC)

  2. Fast and Flexible: Argentine Ants Recruit from Nearby Trails

    PubMed Central

    Flanagan, Tatiana P.; Pinter-Wollman, Noa M.; Moses, Melanie E.; Gordon, Deborah M.

    2013-01-01

    Argentine ants (Linepithema humile) live in groups of nests connected by trails to each other and to stable food sources. In a field study, we investigated whether some ants recruit directly from established, persistent trails to food sources, thus accelerating food collection. Our results indicate that Argentine ants recruit nestmates to food directly from persistent trails, and that the exponential increase in the arrival rate of ants at baits is faster than would be possible if recruited ants traveled from distant nests. Once ants find a new food source, they walk back and forth between the bait and sometimes share food by trophallaxis with nestmates on the trail. Recruiting ants from nearby persistent trails creates a dynamic circuit, like those found in other distributed systems, which facilitates a quick response to changes in available resources. PMID:23967129

  3. The Argentine ant: challenges in managing an invasive unicolonial pest.

    PubMed

    Silverman, Jules; Brightwell, Robert John

    2008-01-01

    The Argentine ant, Linepithema humile, has invaded urban, agricultural, and natural habitats worldwide, causing economic damage and disrupting ecosystem processes. Introduced populations of L. humile and those of many other invasive ants tend to be unicolonial, forming expansive, multiqueened supercolonies that dominate native ant communities and challenge control practices in managed habitats. Argentine ant management typically entails the application of residual insecticide liquids, granules, or baits to only a portion of the colony, resulting in fairly rapid reinfestation. We suggest that prevailing control methodologies are incomplete and not compatible with the behavior, nesting habits, and population structure of this ant, and therefore, more aggressive management strategies are required. Successful eradication efforts against other invasive unicolonial ant species can provide useful insights for local-scale L. humile eradication. PMID:17877449

  4. Argentine Valuation of the EQ-5D Health States

    PubMed Central

    Augustovski, Federico Ariel; Irazola, Vilma Edit; Velazquez, Alberto Pascual; Gibbons, Luz; Craig, Benjamin M.

    2013-01-01

    Objective To develop a set of EQ-5D health state values for the Argentine general population. Methods Consecutive subjects attending six primary care centers in Argentina were selected based on quota sampling and interviewed using the EuroQol Group protocol for measurement and valuation of health studies. Initially respondents were randomly assigned a unique card set; however, to improve efficiency, subjects were later randomly assigned to one of three fixed sets of EQ-5D states. Using the VAS and TTO responses for these states, we estimated a valuation model using ordinary least squares regression clustered by respondent. Predicted values for EQ-5D health states are compared to published values for the United States. Results Six hundred eleven subjects were interviewed by 14 trained interviewers, rendering 6,887 TTO and 6,892 VAS responses. The model had an R2 of 0.897 and 0.928 for TTO and VAS respectively. The mean absolute difference between observed and predicted values was 0.039 for TTO and 0.020 for VAS, each showing a Lin’s concordance coefficient above 0.98. United States and Argentine TTO predicted values were highly correlated (Pearson’s rho=0.963), though the average absolute difference was clinically meaningful (0.06), rejecting the US values for nearly two thirds of the states (62.8%). The Argentine population placed lower values on mild states and higher values on severe states. Conclusion This study provides an Argentine value set that could be used locally or regionally, with meaningful and significant differences with that of the US. Health policy in Latin America must incorporate local values for sovereignty and validity. PMID:19900257

  5. Argentine Population Genetic Structure: Large Variance in Amerindian Contribution

    PubMed Central

    Seldin, Michael F.; Tian, Chao; Shigeta, Russell; Scherbarth, Hugo R.; Silva, Gabriel; Belmont, John W.; Kittles, Rick; Gamron, Susana; Allevi, Alberto; Palatnik, Simon A.; Alvarellos, Alejandro; Paira, Sergio; Caprarulo, Cesar; Guillerón, Carolina; Catoggio, Luis J.; Prigione, Cristina; Berbotto, Guillermo A.; García, Mercedes A.; Perandones, Carlos E.; Pons-Estel, Bernardo A.; Alarcon-Riquelme, Marta E.

    2011-01-01

    Argentine population genetic structure was examined using a set of 78 ancestry informative markers (AIMs) to assess the contributions of European, Amerindian, and African ancestry in 94 individuals members of this population. Using the Bayesian clustering algorithm STRUCTURE, the mean European contribution was 78%, the Amerindian contribution was 19.4%, and the African contribution was 2.5%. Similar results were found using weighted least mean square method: European, 80.2%; Amerindian, 18.1%; and African, 1.7%. Consistent with previous studies the current results showed very few individuals (four of 94) with greater than 10% African admixture. Notably, when individual admixture was examined, the Amerindian and European admixture showed a very large variance and individual Amerindian contribution ranged from 1.5 to 84.5% in the 94 individual Argentine subjects. These results indicate that admixture must be considered when clinical epidemiology or case control genetic analyses are studied in this population. Moreover, the current study provides a set of informative SNPs that can be used to ascertain or control for this potentially hidden stratification. In addition, the large variance in admixture proportions in individual Argentine subjects shown by this study suggests that this population is appropriate for future admixture mapping studies. PMID:17177183

  6. Reactor

    DOEpatents

    Evans, Robert M.

    1976-10-05

    1. A neutronic reactor having a moderator, coolant tubes traversing the moderator from an inlet end to an outlet end, bodies of material fissionable by neutrons of thermal energy disposed within the coolant tubes, and means for circulating water through said coolant tubes characterized by the improved construction wherein the coolant tubes are constructed of aluminum having an outer diameter of 1.729 inches and a wall thickness of 0.059 inch, and the means for circulating a liquid coolant through the tubes includes a source of water at a pressure of approximately 350 pounds per square inch connected to the inlet end of the tubes, and said construction including a pressure reducing orifice disposed at the inlet ends of the tubes reducing the pressure of the water by approximately 150 pounds per square inch.

  7. Trail pheromone of the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae).

    PubMed

    Choe, Dong-Hwan; Villafuerte, David B; Tsutsui, Neil D

    2012-01-01

    The Argentine ant (Linepithema humile) is recognized as one of the world's most damaging invasive species. One reason for the ecological dominance of introduced Argentine ant populations is their ability to dominate food and habitat resources through the rapid mobilization and recruitment of thousands of workers. More than 30 years ago, studies showed that (Z)-9-hexadecenal strongly attracted Argentine ant workers in a multi-choice olfactometer, suggesting that (Z)-9-hexadecenal might be the trail pheromone, or a component of a trail pheromone mixture. Since then, numerous studies have considered (Z)-9-hexadecenal as the key component of the Argentine ant trails. Here, we report the first chemical analyses of the trails laid by living Argentine ants and find that (Z)-9-hexadecenal is not present in a detectible quantity. Instead, two iridoids, dolichodial and iridomyrmecin, appear to be the primary chemical constituents of the trails. Laboratory choice tests confirmed that Argentine ants were attracted to artificial trails comprised of these two chemicals significantly more often than control trails. Although (Z)-9-hexadecenal was not detected in natural trails, supplementation of artificial dolichodial+iridomyrmecin trails with an extremely low concentraion of (Z)-9-hexadecenal did increase the efficacy of the trail-following behavior. In stark contrast with previous dogma, our study suggests that dolichodial and iridomyrmecin are major components of the Argentine ant trail pheromone. (Z)-9-hexadecenal may act in an additive manner with these iridoids, but it does not occur in detectable quantities in Argentine ant recruitment trails. PMID:23028739

  8. Deterrency and Toxicity of Essential Oils to Argentine and Red Imported Fire Ants (Hymenoptera: Formicidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Laboratory assays were conducted to evaluate deterrency and contact toxicity of six essential oils to the Argentine ant, Linepithema humile (Mayr), and the red imported fire ant, Solenopsis invicta Buren. In choice tests, both Argentine ants and fire ants crossed barriers treated with multiple rates...

  9. Trail Pheromone Disruption of Argentine Ant Trail Formation and Foraging

    USGS Publications Warehouse

    Suckling, D.M.; Peck, R.W.; Stringer, L.D.; Snook, K.; Banko, P.C.

    2010-01-01

    Trail pheromone disruption of invasive ants is a novel tactic that builds on the development of pheromone-based pest management in other insects. Argentine ant trail pheromone, (Z)-9-hexadecenal, was formulated as a micro-encapsulated sprayable particle and applied against Argentine ant populations in 400 m2 field plots in Hawai'i Volcanoes National Park. A widely dispersed point source strategy for trail pheromone disruption was used. Traffic rates of ants in bioassays of treated filter paper, protected from rainfall and sunlight, indicated the presence of behaviorally significant quantities of pheromone being released from the formulation for up to 59 days. The proportion of plots, under trade wind conditions (2-3 m s-1), with visible trails was reduced for up to 14 days following treatment, and the number of foraging ants at randomly placed tuna-bait cards was similarly reduced. The success of these trail pheromone disruption trials in a natural ecosystem highlights the potential of this method for control of invasive ant species in this and other environments. ?? Springer Science+Business Media, LLC 2010.

  10. Trail pheromone disruption of Argentine ant trail formation and foraging.

    PubMed

    Suckling, David Maxwell; Peck, Robert W; Stringer, Lloyd D; Snook, Kirsten; Banko, Paul C

    2010-01-01

    Trail pheromone disruption of invasive ants is a novel tactic that builds on the development of pheromone-based pest management in other insects. Argentine ant trail pheromone, (Z)-9-hexadecenal, was formulated as a micro-encapsulated sprayable particle and applied against Argentine ant populations in 400 m2 field plots in Hawai'i Volcanoes National Park. A widely dispersed point source strategy for trail pheromone disruption was used. Traffic rates of ants in bioassays of treated filter paper, protected from rainfall and sunlight, indicated the presence of behaviorally significant quantities of pheromone being released from the formulation for up to 59 days. The proportion of plots, under trade wind conditions (2–3 m s−1), with visible trails was reduced for up to 14 days following treatment, and the number of foraging ants at randomly placed tuna-bait cards was similarly reduced. The success of these trail pheromone disruption trials in a natural ecosystem highlights the potential of this method for control of invasive ant species in this and other environments. PMID:20077128

  11. Activity of Bifenthrin, Chlorfenapyr, Fipronil, and Thiamethoxam against Argentine Ants (Hymenoptera: Formicidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bifenthrin, chlorfenapyr, fipronil, and thiamethoxam were evaluated for activity against the Argentine ant, Linepithema humile (Mayr). Mobility impairment and lethal times were determined following topical treatments. Ants were immobilized most quickly by bifenthrin, followed by chlorfenapyr and th...

  12. TGS pipeline primed for Argentine growth, CEO says

    SciTech Connect

    Share, J.

    1997-03-01

    Nowhere in Latin America has the privatization process been more aggressively pursued than in Argentina where President Carlos Menem has successfully turned over the bulk of state companies to the private sector. In the energy sector, that meant the divestiture in 1992 of Gas del Estado, the state-owned integrated gas transportation and distribution company. It was split in two transportation companies: Transportadora de Gas del Sur (TGS) and Transportadora de Gas del Norte (TGN), and eight distribution companies. TGS is the largest transporter of natural gas in Argentina, delivering more than 60 percent of that nation`s total gas consumption with a capacity of 1.9 Bcf/d. This is the second in a series of Pipeline and Gas Journal special reports that discuss the evolving strategies of the natural gas industry as it continues to restructure amid deregulation. The article focuses on TGS, the Argentine pipeline system in which Enron Corp. is a key participant.

  13. Tectonics of the Argentine and Chilean Andes: An introduction

    NASA Astrophysics Data System (ADS)

    Folguera, Andrés; Alvarado, Patricia; Arriagada, César; Ramos, Victor A.

    2015-12-01

    This Special Issue gathers a series of contributions derived from presentations at the 19° Congreso Geológico Argentino held in Córdoba in 2-6 June 2014. Specific subjects cover a wide variety of topics and regions of the Argentine and Chilean Andes, varying from sedimentological analyses and U/Pb dating of detrital zircons in different rocks to determine source areas for different times and regions along the southern Andes; satellite gravity data for monitoring earthquakes at the subduction zone to understand their complex rupture structure; fission track data from the Andes to the foreland region; use of seismic tomographies and conventional seismic reflection data for analyzing crustal structure; to paleomagnetic data and structural and morphological analyses (Fig. 1).

  14. Colorado Basin Structure and Rifting, Argentine passive margin

    NASA Astrophysics Data System (ADS)

    Autin, Julia; Scheck-Wenderoth, Magdalena; Loegering, Markus; Anka, Zahie; Vallejo, Eduardo; Rodriguez, Jorge; Marchal, Denis; Reichert, Christian; di Primio, Rolando

    2010-05-01

    The Argentine margin presents a strong segmentation with considerable strike-slip movements along the fracture zones. We focus on the volcanic segment (between the Salado and Colorado transfer zones), which is characterized by seaward dipping reflectors (SDR) all along the ocean-continent transition [e.g. Franke et al., 2006; Gladczenko et al., 1997; Hinz et al., 1999]. The segment is structured by E-W trending basins, which differs from the South African margin basins and cannot be explained by classical models of rifting. Thus the study of the relationship between the basins and the Argentine margin itself will allow the understanding of their contemporary development. Moreover the comparison of the conjugate margins suggests a particular evolution of rifting and break-up. We firstly focus on the Colorado Basin, which is thought to be the conjugate of the well studied Orange Basin [Hirsch et al., 2009] at the South African margin [e.g. Franke et al., 2006]. This work presents results of a combined approach using seismic interpretation and structural, isostatic and thermal modelling highlighting the structure of the crust. The seismic interpretation shows two rift-related discordances: one intra syn-rift and the break-up unconformity. The overlying sediments of the sag phase are less deformed (no sedimentary wedges) and accumulated before the generation of oceanic crust. The axis of the Colorado Basin trends E-W in the western part, where the deepest pre-rift series are preserved. In contrast, the basin axis turns to a NW-SE direction in its eastern part, where mainly post-rift sediments accumulated. The most distal part reaches the margin slope and opens into the oceanic basin. The general basin direction is almost orthogonal to the present-day margin trend. The most frequent hypothesis explaining this geometry is that the Colorado Basin is an aborted rift resulting from a previous RRR triple junction [e.g. Franke et al., 2002]. The structural interpretation

  15. Soils of the Galindez Island, Argentine archipelago, Western Antarctica

    NASA Astrophysics Data System (ADS)

    Abakumov, Evgeny; Parnikoza, Ivan

    2015-04-01

    Antarctic Peninsula is a part of Antarctica which is characterized by increased soil diversity, caused by specific of parent materials and diversity of non-vascular and vascular plants. Soils of Galindez Island have been investigated during the 18-th Ukranian Antarctic Expedition 2013/14. This Island situated in Argentine archipelago (coastal part of Antarctic Peninsula). Soils of Galindez Island presented by following types: Leptosols, Lithosols, Histic Lithosols and Leptosols and some Gleyic soils, located in lowlands and coastal parts. An average solum profile thickness is 3-19 cm which result from the small depth of debris's, underplayed by massive crystallic rocks. The permafrost layer is located within the massive rock, but not in coarse friable parent material. The soils with bird influence are widely spread both in coastal and central part of Island. In the coastal parts we can find typical Ornithosols in the penguin rockeries areas. The main aim of our investigation was characterization of soils formed under vegetation, exactly under Deschampsia antarctica Desv. localities. Argentine Islands is the central part of D. antarctica spreading area in region of Antarctic peninsula. Probably, these islands colonized by hairgrass mainly due to ornitogenic activity. So, coastal population appearance related with Larus dominicanus nest areas and feeding activity. Thus, we found typical post ornithogenic soils here. This kind of soils we also observed in population of hairgrass of Galindez mainland where it was connected with the other Antarctic bird - Catharacta maccormicki activity. Thus, the soil diversity and soil geochemistry of the Galindez Island are closely related to the activity of birds. The spatial pattern of soils, their chemistry and organic matter quality is discussed in relation with distribution of bird nesting and feeding activity.

  16. Testing baits to control Argentine ants (Hymenoptera: Formicidae) in vineyards.

    PubMed

    Daane, Kent M; Cooper, Monica L; Sime, Karen R; Nelson, Erik H; Battany, Mark C; Rust, Michael K

    2008-06-01

    Liquid baits were evaluated for control of the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), and associated mealybug and soft scale pests in California vineyards. In 2003, liquid baits with small doses ofimidacloprid, boric acid, or thiamethoxam dissolved in 25% sucrose water resulted in lower ant and mealybug densities and fruit damage, compared with an untreated control. Similar treatments in a soft scale-infested vineyard showed only a reduction of ant density and fruit infestation in only the boric acid and thiamethoxam treatments. In 2004, commercial and noncommercial formulations of liquid baits reduced ant densities in three separate trials, but they had inconsistent effects on mealybug densities and fruit infestation; granular protein bait had no effect. Using large plots and commercial application methodologies, liquid bait deployed in June resulted in lower ant density and fruit infestation, but it had no effect on mealybug density. Across all trials, liquid bait treatments resulted in lower ant density (12 of 14 trials) and fruit damage (11 of 14 sites), presenting the first report of liquid baits applied using commercial methodologies that resulted in a reduction of ants and their associated hemipteran crop damage. For commercialization of liquid baits, we showed that any of the tested insecticides can suppress Argentine ants when properly delivered in the crop system. For imidacloprid, bait dispensers must be protected from sunlight to reduce photodegradation. Results suggest that incomplete ant suppression can suppress mealybug densities. However, after ant populations are suppressed, there may be a longer period before hemipteran populations are effectively suppressed. Therefore, liquid baits should be considered part of a multiseason program rather than a direct, in-season control of hemipteran pest populations. PMID:18613568

  17. The crustal structure of the southern Argentine margin

    NASA Astrophysics Data System (ADS)

    Becker, Katharina; Franke, Dieter; Schnabel, Michael; Schreckenberger, Bernd; Heyde, Ingo; Krawczyk, Charlotte M.

    2012-06-01

    Multichannel reflection seismic profiles, combined with gravimetric and magnetic data provide insight into the crustal structure of the southernmost Argentine margin, at the transition from a rifted to a transform margin and outline the extent of the North Falkland Graben. Based on these data, we establish a regional stratigraphic model for the post-rift sediments, comprising six marker horizons with a new formation in the Barremian/Lower Cretaceous. Our observations support that a N-S trending subsidiary branch of the North Falkland Graben continues along the continental shelf and slope to the Argentine basin. During the rift phase, a wide shelf area was affected by the E-W extension, subsequently forming the North Falkland Graben and the subsidiary branch along which finally breakup occurred. We propose the division of the margin in two segments: a N-S trending rifted margin and an E-W trending transform margin. This is further underpinned by crustal scale gravity modelling. Three different tectono-dynamic processes shaped the study area. (1) The Triassic/Early Jurassic extensional phase resulting in the formation of the North Falkland Graben and additional narrower rift grabens ended synchronously with the breakup of the South Atlantic in the early Valanginian. (2) Extensional phase related to the opening of the South Atlantic. (3) The transform margin was active in the study area from about Hauterivian times and activity lasted until late Cretaceous/early Cenozoic. Both, the rifted margin and the transform margin are magma-poor. Very limited structures may have a volcanic origin but are suggested to be post-rift. The oceanic crust was found to be unusually thin, indicating a deficit in magma supply during formation. These findings in combination with the proposed breakup age in the early Valanginian that considerably predates the formation of the Paraná-Etendeka continental flood basalt provinces in Brazil and Namibia question the influence of the Tristan da

  18. Cross-protection in nonhuman primates against Argentine hemorrhagic fever.

    PubMed Central

    Weissenbacher, M C; Coto, C E; Calello, M A; Rondinone, S N; Damonte, E B; Frigerio, M J

    1982-01-01

    The susceptibility of the marmoset Callithrix jacchus to Tacaribe virus infection was investigated to perform cross-protection studies between Junin and Tacaribe viruses. Five marmosets inoculated with Tacaribe virus failed to show any signs of disease, any alterations in erythrocyte, leukocyte, reticulocyte, and platelet counts or any changes in hematocrit or hemoglobin values. No Tacaribe virus could be recovered from blood at any time postinfection. Anti-Tacaribe neutralizing antibodies appeared 3 weeks postinfection. The five Tacaribe-infected marmosets and four noninfected controls were challenged with the pathogenic strain of Junin virus on day 60 post-Tacaribe infection. The former group showed no signs of disease, no viremia, and no challenge virus replication, whereas the control group exhibited the typical symptoms of Argentine hemorrhagic fever, high viremia, and viral titers in organs. Soon after challenge, the Tacaribe-protected marmosets synthesized neutralizing antibodies against Junin virus. These results indicate that the marmoset C. jacchus can be considered an experimental model for protection studies with arenaviruses and that the Tacaribe virus could be considered as a potential vaccine against Junin virus. PMID:6276301

  19. Argentine ant trail pheromone disruption is mediated by trail concentration.

    PubMed

    Suckling, David Maxwell; Stringer, Lloyd D; Corn, Joshua E

    2011-10-01

    Argentine ant trail pheromone disruption, using continuous release of the trail pheromone compound (Z)-9-hexadecanal, reduces the incidence of trails and foraging rates of field populations. However, little is known about the concentrations of pheromone required for successful disruption. We hypothesized that higher pheromone quantities would be necessary to disrupt larger ant populations. To test this, we laid a 30-cm long base trail of (Z)-9-hexadecanal on a glass surface at low and high rates (1 and 100 pg/cm) (Trail 1), and laid a second, shorter trail (Trail 2, 10 cm long, located 1.5 cm upwind) near the middle of Trail 1 at six rates (1, 10, 100, 1,000, 10,000, and 100,000 pg/cm). We then recorded and digitized movements of individual ants following Trail 1, and derived a regression statistic, r (2), as an index of trail integrity, and also recorded arrival success at the other end of the trail (30 cm) near a food supply. Disruption of trails required 100 fold more pheromone upwind, independent of base-trail concentration. This implies that in the field, trail disruption is likely to be less successful against high ant-trail densities (greater concentration of trail pheromone), and more successful against newly formed or weak trails, as could be expected along invasion fronts. PMID:21964852

  20. Chemical signals associated with life inhibit necrophoresis in Argentine ants.

    PubMed

    Choe, Dong-Hwan; Millar, Jocelyn G; Rust, Michael K

    2009-05-19

    One of the most conspicuous and stereotyped activities of social insects such as ants and honey bees is necrophoresis, the removal of dead colony members from the nest. Previous researchers suggested that decomposition products such as fatty acids trigger necrophoric behavior by ant workers. However, fatty acids elicit both foraging and necrophoric responses, depending on the current nest activities (e.g., feeding or nest maintenance). Furthermore, workers often carry even freshly killed workers (dead for <1 h) to refuse piles before significant decomposition has a chance to occur. Here, we show that the cuticular chemistry of Argentine ant workers, Linepithema humile, undergoes rapid changes after death. When the workers are alive or freshly killed, relatively large amounts of 2 characteristic ant-produced compounds, dolichodial and iridomyrmecin, are present on the ants' cuticle. However, these compounds disappear from the cuticle within about 1 h after death. We demonstrate how this phenomenon supports an alternative mechanism of ant necrophoresis in which the precise recognition and rapid removal of dead nestmates are elicited by the disappearance of these chemical signals associated with life. PMID:19416815

  1. Insecticide Transfer Efficiency and Lethal Load in Argentine Ants

    SciTech Connect

    Hooper-Bui, L. M.; Kwok, E S.C.; Buchholz, B. A.; Rust, M. K.; Eastmond, D. A.; Vogel, J. S.

    2015-07-03

    Trophallaxis between individual worker ants and the toxicant load in dead and live Argentine ants (Linepithema humile) in colonies exposed to fipronil and hydramethylnon experimental baits were examined using accelerator mass spectrometry (AMS). About 50% of the content of the crop containing trace levels of 14C-sucrose, 14C-hydramethylnon, and 14C-fipronil was shared between single donor and recipient ants. Dead workers and queens contained significantly more hydramethylnon (122.7 and 22.4 amol/μg ant, respectively) than did live workers and queens (96.3 and 10.4 amol/μg ant, respectively). Dead workers had significantly more fipronil (420.3 amol/μg ant) than did live workers (208.5 amol/μg ant), but dead and live queens had equal fipronil levels (59.5 and 54.3 amol/μg ant, respectively). Moreover, the distribution of fipronil differed within the bodies of dead and live queens; the highest amounts of fipronil were recovered in the thorax of dead queens whereas live queens had the highest levels in the head. Resurgence of polygynous ant colonies treated with hydramethylnon baits may be explained by queen survival resulting from sublethal doses due to a slowing of trophallaxis throughout the colony. The bait strategies and dose levels for controlling insect pests need to be based on the specific toxicant properties and trophic strategies for targeting the entire colony.

  2. Insecticide Transfer Efficiency and Lethal Load in Argentine Ants

    DOE PAGESBeta

    Hooper-Bui, L. M.; Kwok, E S.C.; Buchholz, B. A.; Rust, M. K.; Eastmond, D. A.; Vogel, J. S.

    2015-07-03

    Trophallaxis between individual worker ants and the toxicant load in dead and live Argentine ants (Linepithema humile) in colonies exposed to fipronil and hydramethylnon experimental baits were examined using accelerator mass spectrometry (AMS). About 50% of the content of the crop containing trace levels of 14C-sucrose, 14C-hydramethylnon, and 14C-fipronil was shared between single donor and recipient ants. Dead workers and queens contained significantly more hydramethylnon (122.7 and 22.4 amol/μg ant, respectively) than did live workers and queens (96.3 and 10.4 amol/μg ant, respectively). Dead workers had significantly more fipronil (420.3 amol/μg ant) than did live workers (208.5 amol/μg ant), butmore » dead and live queens had equal fipronil levels (59.5 and 54.3 amol/μg ant, respectively). Moreover, the distribution of fipronil differed within the bodies of dead and live queens; the highest amounts of fipronil were recovered in the thorax of dead queens whereas live queens had the highest levels in the head. Resurgence of polygynous ant colonies treated with hydramethylnon baits may be explained by queen survival resulting from sublethal doses due to a slowing of trophallaxis throughout the colony. The bait strategies and dose levels for controlling insect pests need to be based on the specific toxicant properties and trophic strategies for targeting the entire colony.« less

  3. Insecticide transfer efficiency and lethal load in Argentine ants

    NASA Astrophysics Data System (ADS)

    Hooper-Bui, L. M.; Kwok, E. S. C.; Buchholz, B. A.; Rust, M. K.; Eastmond, D. A.; Vogel, J. S.

    2015-10-01

    Trophallaxis between individual worker ants and the toxicant load in dead and live Argentine ants (Linepithema humile) in colonies exposed to fipronil and hydramethylnon experimental baits were examined using accelerator mass spectrometry (AMS). About 50% of the content of the crop containing trace levels of 14C-sucrose, 14C-hydramethylnon, and 14C-fipronil was shared between single donor and recipient ants. Dead workers and queens contained significantly more hydramethylnon (122.7 and 22.4 amol/μg ant, respectively) than did live workers and queens (96.3 and 10.4 amol/μg ant, respectively). Dead workers had significantly more fipronil (420.3 amol/μg ant) than did live workers (208.5 amol/μg ant), but dead and live queens had equal fipronil levels (59.5 and 54.3 amol/μg ant, respectively). The distribution of fipronil differed within the bodies of dead and live queens; the highest amounts of fipronil were recovered in the thorax of dead queens whereas live queens had the highest levels in the head. Resurgence of polygynous ant colonies treated with hydramethylnon baits may be explained by queen survival resulting from sublethal doses due to a slowing of trophallaxis throughout the colony. Bait strategies and dose levels for controlling insect pests need to be based on the specific toxicant properties and trophic strategies for targeting the entire colony.

  4. Antibiotic sensitivity of an Argentine strain collection of Moraxella bovis.

    PubMed

    Zielinski, G; Piscitelli, H; Perez-Monti, H; Stobbs, L A

    2000-01-01

    The antimicrobial susceptibility of 88 isolates of Moraxella bovis of Argentine origin was evaluated for 12 antimicrobials by broth microdilution procedures. The isolates had a minimum inhibitory concentration (MIC90) of < or = 0.06 microg/mL to enrofloxacin; < or = 0.12 microg/mL to ceftiofur; < or = 0.25 microg/mL to ampicillin; < or = 0.5 microg/mL to florfenicol and gentamicin; < or = 1.0 microg/mL to tilmicosin, erythromycin, and oxytetracycline; < or = 4.0 microg/mL to tylosin; < or = 8.0 microg/mL to spectinomycin; < or = 0.25/4.75 microg/mL to trimethoprim/sulfamethoxazole; and > or = 32 microg/mL to lincomycin. Modal MIC values for these antimicrobials were as follows: enrofloxacin, 0.03 microg/mL; ceftiofur, 0.06 pg/mL; ampicillin, 0.25 microg/mL; florfenicol, gentamicin, erythromycin, and oxytetracycline, 0.5 microg/mL; tilmicosin, 1.0 microg/mL; tylosin and spectinomycin, 4.0 microg/mL; lincomycin and erythromycin, 16 microg/mL; and trimethoprim/ sulfamethoxazole, < or = 0.25/4.75 microg/mL. These data show that all antimicrobials except lincomycin have MICs suggestive of sensitivity in vitro, though confirmation of clinical efficacy can only be properly assessed based on pharmacologic and/or clinical data to support the MIC values. PMID:19757583

  5. Monitoring of erythemal irradiance in the Argentine ultraviolet network

    NASA Astrophysics Data System (ADS)

    Cede, Alexander; Luccini, Eduardo; Nuñez, Liliana; Piacentini, Rubén D.; Blumthaler, Mario

    2002-07-01

    The Ultraviolet (UV) Monitoring Network of the Argentine Servicio Meteorológico Nacional (National Weather Service) consists at present of nine stations from 22° to 64° latitude south equipped with biometers, broadband instruments that measure the erythemal irradiance. After a complete calibration of the instruments and reprocessing of the database a preliminary climatology of erythemal irradiance and erythemal exposure was built by analyzing the data of the first 2-4 years for each station. The influence of the measurement interval on the UV Index is quantified. A tropical high-altitude station in the Andean Altiplano reaches top UV Index values of 20 and daily doses of 10.6 kJ/m2, among the highest UV levels worldwide. Characteristic UV lndex and erythemal exposure in the central, most populated areas of Argentina are similar to those in other Southern Hemisphere stations and are higher than in comparable latitude regions of the Northern Hemisphere. The southern stations in the UV network are often affected by the Antarctic ozone hole. By comparing clear-sky irradiance measurements with aerosol-free radiative transfer calculations using the Total Ozone Mapping Spectrometer surface albedo climatology, typical attenuations from 2 to 15% due to aerosols were determined, reaching maxima of 30% at urban locations. On the other hand, increases of ~3-6% due to higher surface albedo were obtained for snow-free conditions, and increases up to 15% were obtained for snow-covered terrain.

  6. [Distribution of Lutzomyia longipalpis in the Argentine Mesopotamia, 2010].

    PubMed

    Salomon, Oscar D; Fernandez, Maria S; Santini, María S; Saavedra, Silvina; Montiel, Natalia; Ramos, Marina A; Rosa, Juan R; Szelag, Enrique A; Martinez, Mariela F

    2011-01-01

    The first case of visceral leishmaniasis (VL) in Argentina was reported in 2006 in Posadas, Misiones. During the summer 2008-2009 Lutzomyia longipalpis, the VL vector, and canine VL cases were already spread along the province of Corrientes. In order to know the distribution of VL risk, systematic captures of the vector were performed between February and March 2010, in 18 areas of the provinces of Entre Ríos and Corrientes, and the city of Puerto Iguazú, Misiones, with a total of 313 traps/night. We confirmed the presence of Lu. longipalpis, for the first time in Chajarí (Entre Ríos), Alvear, La Cruz, Curuzú Cuatiá and Bella Vista (Corrientes), and Puerto Iguazú (Misiones). In Santo Tome and Monte Caseros (Corrientes), where the vector had been previously reported, traps with more samples were obtained with 830 and 126 Lu. Longipalpis trap/site/night respectively. These results show that the vector of urban VL continues spreading in the Argentine territory. Simultaneously, the spread of the parasite and the resulting human VL cases are associated with the dispersion of reservoirs, infected dogs, with or without clinical symptoms or signs, due to human transit. PMID:21296716

  7. Feeding strategy of juvenile (age-0+ year) Argentine hake Merluccius hubbsi in the Patagonian nursery ground.

    PubMed

    Temperoni, B; Viñas, M D; Buratti, C C

    2013-11-01

    Age-0+ year juvenile Argentine hake Merluccius hubbsi (60-150 mm total length, L(T)) from San Jorge Gulf, north Patagonian shelf region of the Argentine Sea, had an almost exclusively pelagic diet dominated by the hyperiid amphipod Themisto gaudichaudii and the euphausiid Euphausia lucens. This suggested that final settlement and permanent demersal habitat utilization might not, as previously reported, occur at earlier sizes (c. 20 mm L(T)). Their feeding strategy involves specialization at a population level towards both the main pelagic prey, indicating a narrow trophic niche. Novel data are provided which contribute to the growing body of information in relation to the age-0+ year transitional stage in demersal fishes and particularly to M. hubbsi recruitment in the Argentine Sea. PMID:24580669

  8. Biotic and abiotic controls of argentine ant invasion success at local and landscape scales

    USGS Publications Warehouse

    Menke, S.B.; Fisher, R.N.; Jetz, W.; Holway, D.A.

    2007-01-01

    Although the ecological success of introduced species hinges on biotic interactions and physical conditions, few experimental studies - especially on animals - have simultaneously investigated the relative importance of both types of factors. The lack of such research may stem from the common assumption that native and introduced species exhibit similar environmental tolerances. Here we combine experimental and spatial modeling approaches (1) to determine the relative importance of biotic and abiotic controls of Argentine ant (Linepithema humile) invasion success, (2) to examine how the importance of these factors changes with spatial scale in southern California (USA), and (3) to assess how Argentine ants differ from native ants in their environmental tolerances. A factorial field experiment that combined native ant removal with irrigation revealed that Argentine ants failed to invade any dry plots (even those lacking native ants) but readily invaded all moist plots. Native ants slowed the spread of Argentine ants into irrigated plots but did not prevent invasion. In areas without Argentine ants, native ant species showed variable responses to irrigation. At the landscape scale, Argentine ant occurrence was positively correlated with minimum winter temperature (but not precipitation), whereas native ant diversity increased with precipitation and was negatively correlated with minimum winter temperature. These results are of interest for several reasons. First, they demonstrate that fine-scale differences in the physical environment can eclipse biotic resistance from native competitors in determining community susceptibility to invasion. Second, our results illustrate surprising complexities with respect to how the abiotic factors limiting invasion can change with spatial scale, and third, how native and invasive species can differ in their responses to the physical environment. Idiosyncratic and scale-dependent processes complicate attempts to forecast where

  9. Combined effect of hemipteran control and liquid bait on Argentine ant populations.

    PubMed

    Brightwell, R J; Bambara, S B; Silverman, J

    2010-10-01

    The invasive Argentine ant, Linepithema humile (Mayr), has become a worldwide problem capable of inflicting significant ecological and economic injury on urban, agricultural, and natural environments. The mobility of this pest ant has long been noted, rapidly moving nests to new food resources and then away as resources are depleted. This ant, like many pest ant species, has a special affinity for honeydew excreted by phloem-feeding Hemiptera. We investigated the effect of various hemipteran control strategies on terrapin scale densities and measured their indirect effect on local Argentine ant densities and foraging effort. We then determined whether this indirect treatment strategy improved the performance of an ant bait. We predicted that Argentine ants would move nests away from trees treated for Hemiptera and then move nests back when a liquid bait was offered, followed by a decline in ant numbers due to intake of the toxicant. A horticultural oil spray and soil application of the systemic insecticide, imidacloprid, had no effect on terrapin scale numbers. However, trunk-injected dicrotophos caused a reduction in scale and a decline in local Argentine ant nest density and canopy foraging effort. We also recorded a reduction in local Argentine ant ground foraging when large amounts of liquid bait were applied, and we found no evidence that combining dicrotophos with liquid ant bait performed better than each treatment alone. We suggest that a strategy of combined hemipteran control plus application of liquid ant bait can reduce local Argentine ant densities, when both components of this system are highly efficacious. PMID:21061981

  10. Agronomic characterization of the Argentina Indicator Region. [U.S. corn belt and Argentine pampas

    NASA Technical Reports Server (NTRS)

    Hicks, D. R. (Principal Investigator)

    1982-01-01

    An overview of the Argentina indicator region including information on topography, climate, soils and vegetation is presented followed by a regionalization of crop livestock land use. Corn/soybean production and exports as well as agricultural practices are discussed. Similarities and differences in the physical agronomic scene, crop livestock land use and agricultural practices between the U.S. corn belt and the Argentine pampa are considered. The Argentine agricultural economy is described. Crop calendars for the Argentina indicator region, an accompanying description, notes on crop-livestock zones, wheat production, field size, and agricultural problems and practices are included.

  11. [A century of legislation as regards Italy-Argentine immigration, 1860-1960].

    PubMed

    Olivieri, M

    1987-01-01

    This paper analyzes the changes in Argentine laws regarding migration, mainly in the hundred years since the Argentine Constitution was passed until the 1950s. The different subsequent laws and the debates they caused are related by the author to the political and ideological trends dominating Argentina in that period as to the characteristics and oscillations of the migratory afflux. Further the paper considers Italian laws and migration policies during the same period. The author concludes that after a liberal migration policy in the 19th century, growing legal restrictions and passionate discussion on the role of immigrants followed in this century, particularly between the 2 World Wars. PMID:12269146

  12. DNA Barcoding Identifies Argentine Fishes from Marine and Brackish Waters

    PubMed Central

    Mabragaña, Ezequiel; Díaz de Astarloa, Juan Martín; Hanner, Robert; Zhang, Junbin; González Castro, Mariano

    2011-01-01

    Background DNA barcoding has been advanced as a promising tool to aid species identification and discovery through the use of short, standardized gene targets. Despite extensive taxonomic studies, for a variety of reasons the identification of fishes can be problematic, even for experts. DNA barcoding is proving to be a useful tool in this context. However, its broad application is impeded by the need to construct a comprehensive reference sequence library for all fish species. Here, we make a regional contribution to this grand challenge by calibrating the species discrimination efficiency of barcoding among 125 Argentine fish species, representing nearly one third of the known fauna, and examine the utility of these data to address several key taxonomic uncertainties pertaining to species in this region. Methodology/Principal Findings Specimens were collected and morphologically identified during crusies conducted between 2005 and 2008. The standard BARCODE fragment of COI was amplified and bi-directionally sequenced from 577 specimens (mean of 5 specimens/species), and all specimens and sequence data were archived and interrogated using analytical tools available on the Barcode of Life Data System (BOLD; www.barcodinglife.org). Nearly all species exhibited discrete clusters of closely related haplogroups which permitted the discrimination of 95% of the species (i.e. 119/125) examined while cases of shared haplotypes were detected among just three species-pairs. Notably, barcoding aided the identification of a new species of skate, Dipturus argentinensis, permitted the recognition of Genypterus brasiliensis as a valid species and questions the generic assignment of Paralichthys isosceles. Conclusions/Significance This study constitutes a significant contribution to the global barcode reference sequence library for fishes and demonstrates the utility of barcoding for regional species identification. As an independent assessment of alpha taxonomy, barcodes provide

  13. Argentine experience in the field of illegal immigration.

    PubMed

    Villar, J M

    1984-01-01

    This article provides a brief history of Argentine policy toward migratory flows from neighboring countries and Europe, and concludes with statistics on the number of foreigners in Argentina in the 1970-80 period. Measures passed during the 1940s and 1950s were aimed at providing amnesty for foreigners who were residing in Argentina without immigrant status. However, the lack of an adequate administrative structure to regulate foreigners at the borders was a drawback for migration authorities and limited the possiblility of applying admission criteria effectively. By 1970, there were 583,000 foreigners from neighboring countries living in Argentina, which represented a 25% increase from 1960. 42% of these migrants were in the metropolitan region of the country, indicative of a shift away from employment in agriculture. Decree No. 87, passed in 1974, represented an extension of a migration policy aimed at granting ample facilities for permanent residence to aliens from contiguous countries and was designed to prevent abuse of clandestine workers by employers. As a result of this measure, 150,000 foreigners were able to settle legally in the country. A 1981 law, yet to be implemented, establishes a new legal framework aimed at fostering immigration and regulating the admission of foreigners. To attain the objective of settling workers in areas of the country considered of prime importance to economic development, the law provides for infrastructural investments and promotional measures in areas such as tax exemption and the granting of credit. The 1980 National Population Census indicated there were 677,000 foreigners from neighboring countries in Argentina. In that year, foreigners comprised 2.4% of the country's population and 3.1% of the inhabitants of the metropolitan region. These figures are indicative of a decline in the growth of immigration, most likely due to the decline in the purchasing power of workers' salaries in the late 1970s. PMID:12339919

  14. Effects of honeydew-producing hemipteran denial on local argentine ant distribution and boric acid bait performance.

    PubMed

    Brightwell, R J; Silverman, J

    2009-06-01

    The Argentine ant is well known for its affinity for honeydew and is often associated with hemipteran outbreaks in agricultural and urban environments. It has been suggested that Argentine ants may be controlled by restricting access to honeydew, thereby forcing the ants to move or by encouraging increased liquid toxicant intake. We tested this possible control strategy by restricting Argentine ant access to the honeydew-producing terrapin scale within the canopy of red maple trees and monitoring ant numbers with pitfall traps and nest counts in the mulch around the tree base. Argentine ant nest numbers fell dramatically in the mulch around ant-excluded trees; however, there was no reduction in Argentine ant numbers caught in pitfalls around trees with or without canopy access. We added 0.5% boric acid bait stations at the base of the red maples and monitored bait consumption. Pitfall and nest counts were not affected by the addition of boric acid, although bait consumption was lower around ant-excluded trees, suggesting that restricting access to honeydew-producing Hemiptera did not enhance bait performance. We attribute this result to the increased distance Argentine ant workers had to trail from nest to bait station when not tending nearby terrapin scale. We suggest an alternative management strategy concentrating direct insecticidal control of Argentine ants around a few host plants infested with honeydew-producing Hemiptera by controlling Hemiptera in nearby host plants. PMID:19610434

  15. Applied Ecology and Control of Imported Fire Ants and Argentine Ants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The red imported fire ant, Solenopsis invicta Buren, and Argentine ant, Linepithema humile (Mayr), are invasive species that are major pests in urban, natural, and agricultural habitats. The goal of this dissertation was to study aspects the chemical sensitivity, behavior, and ecology of each specie...

  16. Argentine Hydrellia Robineau-Desvoidy (Diptera, Ephydridae): new species and key to identification.

    PubMed

    Rodrigues Júnior, Francisco De Assis; Mathis, Wayne Nielsen; Hauser, Martin

    2015-01-01

    Hydrellia egeriae sp. nov., a new species of Hydrellia from Campana (34 14' 04 S, 58 52' 32 W) and Hurlingham (3435'14 S, 5838'27 W), Buenos Aires province, Argentina is described. A key to the Argentine Hydrellia species is presented. PMID:26249060

  17. Schooling and Governance: Pedagogical Knowledge and Bureaucratic Expertise in the Genesis of the Argentine Educational System

    ERIC Educational Resources Information Center

    Southwell, Myriam

    2013-01-01

    The consolidation of the Argentine Federal Government by the 1870s aimed to modernise local society, establish state institutions and reach political stabilisation. Building a modern schooling system articulated both utopia and bureaucracy by establishing the use of knowledge as an instrument of social intervention, vindicating and legitimising…

  18. Draft genome of the globally widespread and invasive Argentine ant (Linepithema humile).

    PubMed

    Smith, Christopher D; Zimin, Aleksey; Holt, Carson; Abouheif, Ehab; Benton, Richard; Cash, Elizabeth; Croset, Vincent; Currie, Cameron R; Elhaik, Eran; Elsik, Christine G; Fave, Marie-Julie; Fernandes, Vilaiwan; Gadau, Jürgen; Gibson, Joshua D; Graur, Dan; Grubbs, Kirk J; Hagen, Darren E; Helmkampf, Martin; Holley, Jo-Anne; Hu, Hao; Viniegra, Ana Sofia Ibarraran; Johnson, Brian R; Johnson, Reed M; Khila, Abderrahman; Kim, Jay W; Laird, Joseph; Mathis, Kaitlyn A; Moeller, Joseph A; Muñoz-Torres, Monica C; Murphy, Marguerite C; Nakamura, Rin; Nigam, Surabhi; Overson, Rick P; Placek, Jennifer E; Rajakumar, Rajendhran; Reese, Justin T; Robertson, Hugh M; Smith, Chris R; Suarez, Andrew V; Suen, Garret; Suhr, Elissa L; Tao, Shu; Torres, Candice W; van Wilgenburg, Ellen; Viljakainen, Lumi; Walden, Kimberly K O; Wild, Alexander L; Yandell, Mark; Yorke, James A; Tsutsui, Neil D

    2011-04-01

    Ants are some of the most abundant and familiar animals on Earth, and they play vital roles in most terrestrial ecosystems. Although all ants are eusocial, and display a variety of complex and fascinating behaviors, few genomic resources exist for them. Here, we report the draft genome sequence of a particularly widespread and well-studied species, the invasive Argentine ant (Linepithema humile), which was accomplished using a combination of 454 (Roche) and Illumina sequencing and community-based funding rather than federal grant support. Manual annotation of >1,000 genes from a variety of different gene families and functional classes reveals unique features of the Argentine ant's biology, as well as similarities to Apis mellifera and Nasonia vitripennis. Distinctive features of the Argentine ant genome include remarkable expansions of gustatory (116 genes) and odorant receptors (367 genes), an abundance of cytochrome P450 genes (>110), lineage-specific expansions of yellow/major royal jelly proteins and desaturases, and complete CpG DNA methylation and RNAi toolkits. The Argentine ant genome contains fewer immune genes than Drosophila and Tribolium, which may reflect the prominent role played by behavioral and chemical suppression of pathogens. Analysis of the ratio of observed to expected CpG nucleotides for genes in the reproductive development and apoptosis pathways suggests higher levels of methylation than in the genome overall. The resources provided by this genome sequence will offer an abundance of tools for researchers seeking to illuminate the fascinating biology of this emerging model organism. PMID:21282631

  19. Library Networks in Less-Developed Countries: Two Argentine Cases and Some Observations.

    ERIC Educational Resources Information Center

    Tang, Donna Taxco

    As an American Library Association/USIA International Library Fellow in Argentina from March to September 1989, the author worked with the Argentine National Protective Commission for People's Libraries. Included in her assignment was a charge "to assist in the development of a popular libraries network in Patagonia," the southernmost region of…

  20. Powerful motors: Kinship, citizenship and the transformation of the Argentine oil industry

    NASA Astrophysics Data System (ADS)

    Shever, Elana

    The privatization of the Argentine oil industry has been described as an unprecedented transfer of property, capital and control from the state to the corporate sphere, but this study demonstrates that the privatization process is better understood as a transformation of the historical configurations of oil-fueled development, political communities and human subjectivities. This dissertation probes the development of the state-led oil industry, and the shift to a corporate-led one, through an ethnography of Argentines differently positioned in relation to the global oil industry. The ethnography explores the lives of middle class oil workers and their families in Northwest Patagonia, impoverished residents of the shanty neighborhoods near the refineries in metropolitan Buenos Aires, and affluent employees of the translocal corporations operating in the Argentine oil fields. After the Introduction delineates this study's four principal interventions into anthropological scholarship, each subsequent chapter engages a particular problem that cuts across the Argentine oil fields and the anthropological theoretical fields. Chapter Two scrutinizes the historical construction of the Argentine subterritory as a "natural" space of value. Chapters Three and Four investigate the articulation of capitalist production and filial reproduction. These chapters argue that sentiment is a crucial generative force that has shaped the oil industry, company towns and worker families from the founding of the state-owned oil company in beginning of the twentieth century to its conversion into a corporate-owned one at the century's close. Chapters Five and Six examine the emergence of consumer citizenship and corporate citizenship out of Argentine neoliberalismo and its transformation of the oil industry. They argue that consumer and corporate citizenship are both reformulations of the older traditions of liberalism and Peronism. All the chapters of this dissertation illustrate that the

  1. Abiotic factors control invasion by Argentine ants at the community scale.

    PubMed

    Menke, Sean B; Holway, David A

    2006-03-01

    1. A prominent and unresolved question in ecology concerns why communities differ in their susceptibility to invasion. While studies often emphasize biotic resistance, it is less widely appreciated how the physical environment affects community vulnerability to invasion. 2. In this study we performed field experiments to test how abiotic variation directly and indirectly influences the extent to which Linepithema humile Mayr (Argentine ants) invade seasonally dry environments in southern California. 3. In controlled and replicated experiments involving drip irrigation, we demonstrate (i) that elevated levels of soil moisture increased both the abundance of Argentine ants and their ability to invade native ant communities and (ii) that cessation of irrigation caused declines in the abundance of Argentine ants and led to their withdrawal from previously occupied areas. 4. Because drip irrigation stimulated plant growth, in an additional experiment we manipulated both soil moisture and plant cover to assess the direct vs. indirect effects of added water on the abundance of L. humile. 5. Local abundance of Argentine ants increased in irrigated plots but was 38% higher in irrigated plots with plants compared to irrigated plots where plant growth was suppressed. The results of this experiment thus argue for a direct role of soil moisture in influencing Argentine ant abundance but suggest that that the indirect effects of added water may also be important. 6. Our study illustrates more generally that fine-scale variation in the physical environment can control whether communities become invaded by non-native species and suggests that an understanding of community susceptibility to invasion will be improved by a better appreciation of interactions between the biotic and abiotic environment. PMID:16637990

  2. Retrieval of granular bait by the Argentine ant (Hymenoptera: Formicidae): effect of clumped versus scattered dispersion patterns.

    PubMed

    Silverman, Jules; Roulston, T'ai H

    2003-06-01

    Argentine ants, Linepithema humile (Mayr), use mass recruitment foraging, with clumped prey items being retrieved more efficiently than dispersed prey. However, in prior field experiments, granular baits, whether dispensed in containers or broadly scattered, had a similar impact on Argentine ant populations. In laboratory experiments, granular insecticide bait was encountered faster by Argentine ant workers and more granules were initially returned to the colony when the granules were scattered versus clumped. After 2 h, granules from both dispersion patterns were retrieved equally. Our results suggest that Argentine ant colonies adjust their foraging patterns to resources of different quality (prey versus bait). Also, foraging activity patterns for bait in the laboratory are consistent with prior field results demonstrating no efficacy advantages to discrete granular bait placements. PMID:12852629

  3. Argentine ant invasion associated with loblolly pines in the southeastern United States: minimal impacts but seasonally sustained.

    PubMed

    Rowles, Alexei D; Silverman, Jules

    2010-08-01

    Invasive ants are notorious for directly displacing native ant species. Although such impacts are associated with Argentine ant invasions (Linepithema humile) worldwide, impacts within natural habitat are less widely reported, particularly those affecting arboreal ant communities. Argentine ants were detected in North Carolina mixed pine-hardwood forest for the first time but were localized on and around loblolly pines (Pinus taeda), probably because of association with honeydew-producing Hemiptera. We explored the potential impacts of L. humile on arboreal and ground-foraging native ant species by comparing interspersed loblolly pines invaded and uninvaded by Argentine ants. Impacts on native ants were assessed monthly over 1 yr by counting ants in foraging trails on pine trunks and in surrounding plots using a concentric arrangement of pitfall traps at 1, 2, and 3 m from the base of each tree. Of floristics and habitat variables, higher soil moisture in invaded plots was the only difference between plot types, increasing confidence that any ant community differences were caused by Argentine ants. Overall patterns of impact were weak. Composition differed significantly between Argentine ant invaded and uninvaded trunks and pitfalls but was driven only by the presence of Argentine ants rather than any resulting compositional change in native ant species. Native ant abundance and richness were similarly unaffected by L. humile. However, the abundance of individual ant species was more variable. Although numbers of the arboreal Crematogaster ashmeadi (Myrmicinae) declined on and around invaded pines, epigeic Aphaenogaster rudis (Myrmicinae) remained the most abundant species in all plots. Argentine ant densities peaked in late summer and fall, therefore overlapping with most native ants. Unexpected was their continued presence during even the coldest months. We provide evidence that Argentine ants can invade and persist in native North Carolina forests, probably

  4. Long-term field trial to control the invasive Argentine ant (Hymenoptera: Formicidae) with synthetic trail pheromone.

    PubMed

    Nishisue, K; Sunamura, E; Tanaka, Y; Sakamoto, H; Suzuki, S; Fukumoto, T; Terayama, M; Tatsuki, S

    2010-10-01

    Previous short-term experiments showed that trail following behavior of the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), can be disrupted by a high concentration of synthetic trail pheromone component (Z)-9-hexadecenal. In this study, a long-term field trial was conducted in 100-m2 plots of house gardens in an urban area of Japan to see whether the control effect on Argentine ants can be obtained by permeating synthetic trail pheromone from dispensers. The dispensers were placed in the experimental plots during the ant's active season (April-November) for 2 yr with monthly renewal. To estimate Argentine ant population density, foraging activity of Argentine ants in the study plots was monitored by monthly bait surveys. Throughout the study period, Argentine ant foraging activity was suppressed in the presence of the dispensers, presumably via trail forming inhibition. In contrast, the level of foraging activity was not different between treatment and no-treatment plots when the dispensers were temporarily removed, suggesting that treatment with pheromone dispensers did not suppress Argentine ant density in the treatment plots. Population decline may be expected with larger-scale treatment that covers a significant portion of the ant colony or with improvement in the potency of the disruptant. PMID:21061980

  5. The source and market development of a premium product - Beef from the Argentine Pampas.

    PubMed

    Champredonde, M

    2008-07-01

    The two main features of beef from the Argentine Pampas are its quality and geographical origin. In addition to the normal aspects of meat quality detected by sensory panels or measured by scientific instruments, the quality of Pampean beef includes the powerful symbolic quality of pampas life - the immensity of the green grasslands and the culture of the gaucho, living on horseback or sipping mate while making an asado (barbecue). This review defines the qualities and geographical origin of Pampean beef, and explains their interrelationships in terms of animal breed, nutrition and production systems. The objective is to help secure Pampean beef against unfair encroachment from competing products which lack the true authenticity of beef from the Argentine Pampas. PMID:22062914

  6. Survey of Argentine Health Researchers on the Use of Evidence in Policymaking

    PubMed Central

    Corluka, Adrijana; Hyder, Adnan A.; Segura, Elsa; Winch, Peter; McLean, Robert K. D.

    2015-01-01

    Objective In this study, Argentine health researchers were surveyed regarding their perceptions of facilitators and barriers to evidence-based policymaking in Argentina, as well as their publication activities, and research environment satisfaction. Methods A self-administered online survey was sent to health researchers in Argentina. The survey questions were based on a preceding qualitative study of Argentine health researchers, as well as the scientific literature. Results Of the 647 researchers that were reached, 226 accessed the survey, for a response rate of 34.9%. Over 80% of researchers surveyed had never been involved in or contributed to decision-making, while over 90% of researchers indicated they would like to be involved in the decision-making process. Decision-maker self-interest was perceived to be the driving factor in the development of health and healthcare policies. Research conducted by a research leader was seen to be the most influential factor in influencing health policy, followed by policy relevance of the research. With respect to their occupational environment, researchers rated highest and most favourably the opportunities available to present, discuss and publish research results and their ability to further their education and training. Argentine researchers surveyed demonstrated a strong interest and willingness to contribute their work and expertise to inform Argentine health policy development. Conclusion Despite Argentina’s long scientific tradition, there are relatively few institutionalized linkages between health research results and health policymaking. Based on the results of this study, the disconnect between political decision-making and the health research system, coupled with fewer opportunities for formalized or informal researcher/decision-maker interaction, contribute to the challenges in evidence informing health policymaking in Argentina. Improving personal contact and the building of relationships between

  7. Vitrification Demonstration with Argentine Ion Exchange Material in the Stir-Melter

    SciTech Connect

    Cicero-Herman, C.A.

    2002-06-28

    The Savannah River Technology Center (SRTC) is investigating the viability of vitrification treatment of Argentine ion exchange material as part of a Department of Energy (DOE) - Office of Science and Technology Development Task Plan. Bench-scale studies were performed by the SRTC to define the necessary vitrification process for this material. However, the process had to be demonstrated in a melter system before vitrification could be considered a viable treatment option.

  8. Draft Genome Sequences of Four Enterococcus faecium Strains Isolated from Argentine Cheese

    PubMed Central

    Martino, Gabriela P.; Quintana, Ingrid M.; Espariz, Martín; Blancato, Victor S.; Gallina Nizo, Gabriel; Esteban, Luis

    2016-01-01

    We report the draft genome sequences of four Enterococcus faecium strains isolated from Argentine regional cheeses. These strains were selected based on their technological properties, i.e., their ability to produce aroma compounds (diacetyl, acetoin, and 2,3-butanediol) from citrate. The goal of our study is to provide further genetic evidence for the rational selection of enterococci strains based on their pheno- and genotype in order to be used in cheese production. PMID:26847907

  9. Draft Genome Sequences of Four Enterococcus faecium Strains Isolated from Argentine Cheese.

    PubMed

    Martino, Gabriela P; Quintana, Ingrid M; Espariz, Martín; Blancato, Victor S; Gallina Nizo, Gabriel; Esteban, Luis; Magni, Christian

    2016-01-01

    We report the draft genome sequences of four Enterococcus faecium strains isolated from Argentine regional cheeses. These strains were selected based on their technological properties, i.e., their ability to produce aroma compounds (diacetyl, acetoin, and 2,3-butanediol) from citrate. The goal of our study is to provide further genetic evidence for the rational selection of enterococci strains based on their pheno- and genotype in order to be used in cheese production. PMID:26847907

  10. Simulation-model evaluation of bovine tuberculosis-eradication strategies in Argentine dairy herds.

    PubMed

    Perez, Andres M; Ward, Michael P; Ritacco, Viviana

    2002-08-30

    We used stochastic modification of the Reed-Frost model to assess the impact of 14 different eradication strategies on bovine tuberculosis, under three scenarios of disease introduction, in Argentine dairy herds. All strategies investigated were based on a test-and-cull approach using either the caudal-fold test (CFT), the single cervical test (SCT), the gamma-interferon (gamma-IFN) test or a combination of these tests. The maximum, minimum and most-likely sensitivity and specificity were investigated in three scenarios simulating different epidemiological conditions. Simulation results were highly variable; therefore, it is difficult to predict the effect of disease-control strategies within individual herds. On average, the use of the SCT was less efficient in eradicating tuberculosis from the simulated herd than the CFT. Eradication would be achieved most efficiently by strategies in which the CFT was used assuming maximum possible sensitivity and specificity (difficult to achieve in the field) and/or the gamma-IFN test-which has both economical and logistical limitations to its widespread application in Argentina. When disease-control was simulated in situations in which herd tuberculosis prevalence is > or = 22%, all strategies we simulated were less efficient than herd depopulation. Considering that Argentine dairy producers are not compensated financially for cattle culled because of tuberculosis, eradication strategies currently used in the Argentine national tuberculosis eradication might not succeed. PMID:12163251

  11. The Haleakala Argentine ant project: a synthesis of past research and prospects for the future.

    USGS Publications Warehouse

    Krushelnycky, Paul; Haines, William; Loope, Lloyd; Van Gelder, Ellen

    2011-01-01

    1. The Haleakala Argentine Ant Project is an ongoing effort to study the ecology of the invasive Argentine ant in the park, and if possible to develop a strategy to control this destructive species. 2. Past research has demonstrated that the Argentine ant causes very significant impacts on native arthropods where it invades, threatening a large portion of the park’s biodiversity in subalpine shrubland and alpine aeolian ecosystems. 3. Patterns of spread over the past 30+ years indicate that the invasion process is influenced to a substantial degree by abiotic factors such as elevation, rainfall and temperature, and that the ant has not reached its potential range. Predictions of total range in the park suggest that it has only invaded a small fraction of available suitable habitat, confirming that this species is one of most serious threats to the park’s natural resources. 4. Numerous experiments have been conducted since 1994 in an attempt to develop a method for eradicating the Argentine ant at Haleakala using pesticidal ant baits. Thirty baits have been screened for attractiveness to ants in the park, and ten of these were tested for effectiveness of control in field plots. While some of these baits have been very effective in reducing numbers of ants, none has been able to eliminate all nests in experimental plots. 5. Research into a secondary management goal of ant population containment was initiated in 1996. By treating only expanding margins of the park’s two ant populations with an ant pesticide, rates of outward spread were substantially reduced in some areas. While this strategy was implemented from 1997 to 2004, it was ultimately discontinued after 2004 because of the difficulty and insufficient effectiveness of the technique. 6. In order to achieve the types of results necessary for eradication, the project would probably need to explore the possibility of developing a specialized bait, rather than relying on a commercially produced bait. An

  12. Hydrological cycles and trends in the NW Argentine Andes since 1940

    NASA Astrophysics Data System (ADS)

    Castino, Fabiana; Bookhagen, Bodo; Strecker, Manfred

    2016-04-01

    Strong spatiotemporal variability characterizes the hydrometeorological pattern in the NW Argentine Andes, draining parts of the most populated and economically important areas of South America. During the summer monsoon season (DJF), the eastern flanks of the central Andes are characterized by deep convection, exposing them to extreme hydrometeorological events. These often result in floods and landslides with disastrous effects on the local populations. Here, we analyze river discharge to explore long-term hydrological variability in NW Argentine Andes and the linked climate controlling processes. We rely on 13 daily river discharge time series relevant to drainage basins spanning several size orders (102-104 km2) starting in 1914 and define different hydro-climate indices both for the mean and the extreme hydrological events. We apply quantile regression to investigate long-term trends and spectral analysis associated with cross-correlation with SST-based climate indices to identify links to large-scale climate variability modes. River discharge presents a pronounced and coherent variability signal in South America, particularly for wide drainage basins, such as the Amazon and Paraná/La Plata rivers, strongly associated to Pacific and Atlantic Oceans Sea Surface Temperature (SST) anomalies (i.e. ENSO, PDO, AMO). Our analysis evidences that in the NW Argentine Andes, mean discharge values are characterized by statistically significant, mostly positive, long-term trends since 1940, whereas the extreme events present a more non-unidirectional trend pattern. Also, coherent multi-annual to multi-decadal cycles characterizing the discharge pattern have been identified, suggesting that processes linked to SST anomaly-modes strongly control the hydrometeorology variability in the NW Argentina Andes.

  13. Hantavirus reservoir Oligoryzomys longicaudatus spatial distribution sensitivity to climate change scenarios in Argentine Patagonia

    PubMed Central

    Carbajo, Aníbal E; Vera, Carolina; González, Paula LM

    2009-01-01

    Background Oligoryzomys longicaudatus (colilargo) is the rodent responsible for hantavirus pulmonary syndrome (HPS) in Argentine Patagonia. In past decades (1967–1998), trends of precipitation reduction and surface air temperature increase have been observed in western Patagonia. We explore how the potential distribution of the hantavirus reservoir would change under different climate change scenarios based on the observed trends. Methods Four scenarios of potential climate change were constructed using temperature and precipitation changes observed in Argentine Patagonia between 1967 and 1998: Scenario 1 assumed no change in precipitation but a temperature trend as observed; scenario 2 assumed no changes in temperature but a precipitation trend as observed; Scenario 3 included changes in both temperature and precipitation trends as observed; Scenario 4 assumed changes in both temperature and precipitation trends as observed but doubled. We used a validated spatial distribution model of O. longicaudatus as a function of temperature and precipitation. From the model probability of the rodent presence was calculated for each scenario. Results If changes in precipitation follow previous trends, the probability of the colilargo presence would fall in the HPS transmission zone of northern Patagonia. If temperature and precipitation trends remain at current levels for 60 years or double in the future 30 years, the probability of the rodent presence and the associated total area of potential distribution would diminish throughout Patagonia; the areas of potential distribution for colilargos would shift eastwards. These results suggest that future changes in Patagonia climate may lower transmission risk through a reduction in the potential distribution of the rodent reservoir. Conclusion According to our model the rates of temperature and precipitation changes observed between 1967 and 1998 may produce significant changes in the rodent distribution in an equivalent

  14. Sea Level Variability of the Argentine Basin From 25 to 5000 Days

    NASA Astrophysics Data System (ADS)

    Fu, L.

    2006-12-01

    While the mean sea level of the global oceans has been rising since the modern recording by tide gauges began over 100 years ago, the details of the spatial variability of sea level are not known until the advent of precision measurement from satellite altimeters slightly more than a decade ago. This new knowledge of spatial variability not only underscores the issue of sampling errors from sparsely located tide gauges; it also reveals the richness of ocean dynamics in affecting sea level changes. An example is given on the sea level of the Argentine Basin of the South Atlantic. The 13 plus years' (5000 days) worth of altimetry data from TOPEX/Poseidon, Jason, and ERS revealed a trend of rising sea level at the center of the basin at a rate greater than 1 cm/year, with strong seasonal-to-interannual variability. The part of sea level variability caused by the change in the heat storage in the upper ocean was estimated from in-situ observations. After subtracting this "thermosteric sea level" from the altimeter observations, the residual sea levels showed an isolated pool of rising trend (greater than 1 cm/year) over the Zapiola Rise (a sediment ridge centered on 45 S, 45 W), suggesting that the barotropic gyre of the Zapiola Anticyclone was spinning up over the past 13 years. In the mean time, the eddy kinetic energy in the surrounding regions also showed significant rising trends, suggesting possible relationship between the Zapiola Anticyclone and the surrounding eddy field on decadal time scales. There is also evidence for energy exchange between eddies and barotropic gyre-scale waves with periods close to 25 days in the Argentine Basin. The apparent interactions among a wide range of scales make the Argentine Basin an interesting and challenging region for theoretical and modeling studies to sort out the mechanisms of the interactions.

  15. ``You are what you eat'': Diet modifies cuticular hydrocarbons and nestmate recognition in the Argentine ant, Linepithema humile

    NASA Astrophysics Data System (ADS)

    Liang, D.; Silverman, J.

    2000-10-01

    Nestmate recognition plays a key role in the behavior and evolution of social insects. We demonstrated that hydrocarbons are the chemical cues used in Argentine ant, Linepithema humile, nestmate recognition, and that these hydrocarbons can be acquired from insect prey. Consequently, Argentine ant cuticular hydrocarbon patterns reveal the same hydrocarbons present in their diet. Diet alters both the recognition cues present on the cuticular surface and the response of nestmates to this new colony odor, resulting in aggression between former nestmates reared on different insect prey.

  16. "You are what you eat": diet modifies cuticular hydrocarbons and nestmate recognition in the Argentine ant, Linepithema humile.

    PubMed

    Liang, D; Silverman, J

    2000-09-01

    Nestmate recognition plays a key role in the behavior and evolution of social insects. We demonstrated that hydrocarbons are the chemical cues used in Argentine ant, Linepithema humile, nestmate recognition, and that these hydrocarbons can be acquired from insect prey. Consequently, Argentine ant cuticular hydrocarbon patterns reveal the same hydrocarbons present in their diet. Diet alters both the recognition cues present on the cuticular surface and the response of nestmates to this new colony odor, resulting in aggression between former nestmates reared on different insect prey. PMID:11091966

  17. Equity during an economic crisis: financing of the Argentine health system.

    PubMed

    Cavagnero, Eleonora; Bilger, Marcel

    2010-07-01

    This article analyses the redistributive effect caused by health financing and the distribution of healthcare utilization in Argentina before and during the severe 2001/2002 economic crisis. Both dramatically changed during this period: the redistributive effect became much more positive and utilization shifted from pro-poor to pro-rich. This clearly demonstrates that when utilization is contingent on financing, changes can occur rapidly; and that an integrated approach is required when monitoring equity. From a policy perspective, the Argentine health system appears vulnerable to economic downturns mainly due to high reliance on out-of-pocket payments and the strong link between health insurance and employment. PMID:20452070

  18. Laboratory and Field Evaluations of Polyacrylamide Hydrogel Baits Against Argentine Ants (Hymenoptera: Formicidae).

    PubMed

    Rust, Michael K; Soeprono, Andrew; Wright, Sarajean; Greenberg, Les; Choe, Dong-Hwan; Boser, Christina L; Cory, Coleen; Hanna, Cause

    2015-06-01

    The development of effective baits to control the Argentine ant, Linepithema humile (Mayr), has been problematic because foragers prefer sweet liquids, while many toxicants are insoluble in water and liquid baits are generally difficult to deliver. The incorporation of thiamethoxam and sucrose solutions into a water-absorbing polyacrylamide hydrogel provides a unique and novel carrier and method of application for liquid baits. Formulations of thiamethoxam affected the size of the hydrogels, and sucrose solutions containing 0.0003% technical thiamethoxam provided hydrogels as large as those made with 25% sucrose solution or deionized water. Concentrations of thiamethoxam as low as 0.000075% in the hydrogels provided 50% kill of workers within 3 d in a laboratory setting. In small colony studies, baiting with 0.00015 and 0.000075% thiamethoxam hydrogels provided 100% mortality of workers and queens within 8 d. An enzyme-linked immunosorbent assay indicated that thiamethoxam was absorbed into the interior of the polyacrylamide matrix. The water loss rates of the hydrogels were dependent upon the relative humidity. Polyacrylamide hydrogels with >50% water loss were less attractive to ants. Field studies in highly infested areas indicated that concentrations of 0.0006 or 0.0018% thiamethoxam were more effective than 0.00015%. Hydrogels may provide a cost-effective alternative to providing aqueous baits to control Argentine ants. PMID:26470250

  19. Potential application of Northern Argentine propolis to control some phytopathogenic bacteria.

    PubMed

    Ordóñez, R M; Zampini, I C; Moreno, M I Nieva; Isla, M I

    2011-10-20

    The antimicrobial activity of samples of Northern Argentine propolis (Tucumán, Santiago del Estero and Chaco) against phytopathogenic bacteria was assessed and the most active samples were identified. Minimal inhibitory concentration (MIC) values were determined by agar macrodilution and broth microdilution assays. Strong antibacterial activity was detected against Erwinia carotovora spp carotovora CECT 225, Pseudomonas syringae pvar tomato CECT 126, Pseudomonas corrugata CECT 124 and Xanthomonas campestris pvar vesicatoria CECT 792. The most active propolis extract (Tucumán, T1) was selected to bioguide isolation and identified for antimicrobial compound (2',4'-dihydroxychalcone). The antibacterial chalcone was more active than the propolis ethanolic extract (MIC values of 0.5-1 μg ml(-1) and 9.5-15 μg ml(-1), respectively). Phytotoxicity assays were realized and the propolis extracts did not retard germination of lettuce seeds or the growth of onion roots. Propolis solutions applied as sprays on tomato fruits infected with P. syringae reduced the severity of disease. Application of the Argentine propolis extracts diluted with water may be promising for the management of post harvest diseases of fruits. PMID:21237629

  20. Portrayals of character smoking and drinking in Argentine-, Mexican- and US-produced films.

    PubMed

    Kollath-Cattano, Christy; Abad-Vivero, Erika N; Mejia, Raul; Perez-Hernandez, Rosaura; Sargent, James D; Thrasher, James F

    2016-09-01

    The aim of this study was to assess film character portrayals of tobacco and alcohol use in US and nationally-produced films that were popular in Argentina and Mexico from 2004-2012. We performed a content analysis of these films (n=82 Argentine, 91 Mexican, and 908 US films, respectively). Chi-squares and t-tests were used to compare characteristics of characters who smoked or drank by country of movie production. Then data from all countries were pooled, and generalized estimating equation (GEE) models were used to determine independent correlates of character smoking or drinking. There were 480 major characters for Argentine-, 364 for Mexican-, and 4962 for US-produced films. Smoking prevalence among movie characters was similar to population smoking prevalence in Mexico (21%) and Argentina (26%), but about half in the US (11%), where movie product placements are restricted. Movie smoking declined over the period in all three countries. Movie alcohol prevalence was 40-50% across all countries and did not change with time. Demographic predictors of character smoking included: being male, 18 and older, having negative character valence. Movie smoking was not associated with lower SES. Predictors of character drinking included: being age 18 and older and positive character valence. Smoking and drinking predicted each other, illicit drug use, and higher scores for other risk behaviors. This suggests that policy development in Mexico and Argentina may be necessary to reduce the amount of character tobacco and alcohol use in films. PMID:27404576

  1. Acceptance and intake of gel and liquid sucrose compositions by the Argentine ant (Hymenoptera: Formicidae).

    PubMed

    Silverman, J; Roulston, T H

    2001-04-01

    Liquids and gels are common delivery forms used in commercial ant baits, but the relative effectiveness of each is unknown. We compared the feeding responses of the Argentine ant, Linepithema humile (Mayr), to liquid and gel compositions of sucrose. In choice assays, more workers were counted on gel than liquid; however, substantially more liquid was consumed. Because workers could stand on the gel, more workers could feed simultaneously on the gel. The feeding bouts of individual workers, however, were much less efficient at extracting sucrose in gel form. Workers fed eightfold longer on the gel, yet removed fivefold less sucrose than workers feeding on liquid. This potential bias should be considered during attraction and palatability studies that use physically different bait compositions. When the toxicant fipronil was added to the compositions, a greater proportion of the colony died after workers had fed on liquid than gel baits. This finding suggests that liquid formulations may provide more effective control of Argentine ants due to the greater speed and abundance in which it is ingested. PMID:11332847

  2. [Consensus guidelines for respiratory endoscopy issued by the Argentine Society of Bronchoesophagology].

    PubMed

    Quadrelli, S; Grynblat, P; Defranchi, H; Downey, D; de la Canal, A; Perrone, R; Schiaffini Mauro, A

    1998-04-01

    The international consensus is that guidelines for respiratory endoscopy are inadequate, regarding such issues as institutional requirements, benefits, risks and limitations of the procedure, training programs and accreditation, with the result that the way or performing endoscopy varies according to how an operator was trained. The absence of precise recommendations means that practice is highly diverse and inappropriate use of the procedure has increased. The Argentine Consensus Group for Normalization of Respiratory Endoscopy was created in 1995 to unify criteria for several aspects of endoscopic practice. The official recommendations of the Group and of the Argentine Society of Bronchoesophagology define the indications (diagnostic, therapeutic and investigative) and contraindications (absolute, relative and high risk) for bronchoscopy. Required pre-bronchoscopic studies for routine and special cases are defined, as are indications for premedication, intubation and general anesthesia. Requirements for the setting, support personal and instruments are specified. Guidelines for topical anesthesia and techniques for insertion of the endoscope are suggested. The technique, indications and limitations of bronchoalveolar lavage, bronchial brushing and biopsy and transbronchial needle biopsy are defined. The utility and limitations of the various therapeutic techniques of bronchoscopy (laser, radiotherapy and stents) are defined. Norms to safeguard the patient, instruments and operator are emphasized. PMID:9611657

  3. Quantitative analysis of the effects of the exotic Argentine ant on seed-dispersal mutualisms

    PubMed Central

    Rodriguez-Cabal, Mariano A.; Stuble, Katharine L.; Nuñez, Martin A.; Sanders, Nathan J.

    2009-01-01

    Although it is increasingly clear that exotic invasive species affect seed-dispersal mutualisms, a synthetic examination of the effect of exotic invasive species on seed-dispersal mutualisms is lacking. Here, we review the impacts of the invasive Argentine ant (Linepithema humile) on seed dispersal. We found that sites with L. humile had 92 per cent fewer native ant seed dispersers than did sites where L. humile was absent. In addition, L. humile did not replace native seed dispersers, as rates of seed removal and seedling establishment were all lower in the presence of L. humile than in its absence. We conclude that potential shifts in plant diversity and concomitant changes in ecosystem function may be a consequence of Argentine ant invasions, as well as invasions by other ant species. Because very few studies have examined the effects of non-ant invasive species on seed-dispersal mutualisms, the prevalence of disruption of seed-dispersal mutualisms by invasive species is unclear. PMID:19465575

  4. Differential use of the Argentine shelf by wintering adults and juveniles southern giant petrels, Macronectes giganteus, from Patagonia

    NASA Astrophysics Data System (ADS)

    Blanco, Gabriela S.; Quintana, Flavio

    2014-08-01

    To study habitat use and at-sea movements of southern giant petrels (SGP) during non-breeding period, we deployed 15 satellite transmitters (six adults, nine juveniles) at Isla Arce and Isla Gran Robredo colonies in Patagonia, Argentina. Birds were instrumented during 81.4 ± 37 days. Adult birds used 74% of the Argentine shelf concentrating mainly at the shelf break, middle shelf waters, and the surroundings of the colony. After fledging, juveniles spread to the Argentine, Uruguayan and Brazilian shelves within the South Atlantic. Adults alternated at-sea excursions (12 ± 5 days) with periods at the colony of 3 ± 0.3 days. Contrarily, juveniles moved first to the shelf break and then traveled northwards reaching the south of Brazil. There was some spatial overlap between age classes, but only during the first 30 days after juveniles had fledged; thereafter there was not overlap between the areas used by both age classes. The Argentine shelf is widely used by different species offering a suitable environment for foraging; this may be why adults SGP from Patagonian colonies spend all year-round within the Argentine shelf. The identification of used areas of non-breeding SGP fills a gap in the species knowledge contributing not only to the preservation the species, but also to the management of marine areas globally recognized as important for many other Procellariiformes.

  5. A mathematical model of foraging in a dynamic environment by trail-laying Argentine ants.

    PubMed

    Ramsch, Kai; Reid, Chris R; Beekman, Madeleine; Middendorf, Martin

    2012-08-01

    Ants live in dynamically changing environments, where food sources become depleted and alternative sources appear. Yet most mathematical models of ant foraging assume that the ants' foraging environment is static. Here we describe a mathematical model of ant foraging in a dynamic environment. Our model attempts to explain recent empirical data on dynamic foraging in the Argentine ant Linepithema humile (Mayr). The ants are able to find the shortest path in a Towers of Hanoi maze, a complex network containing 32,768 alternative paths, even when the maze is altered dynamically. We modify existing models developed to explain ant foraging in static environments, to elucidate what possible mechanisms allow the ants to quickly adapt to changes in their foraging environment. Our results suggest that navigation of individual ants based on a combination of one pheromone deposited during foraging and directional information enables the ants to adapt their foraging trails and recreates the experimental results. PMID:22575583

  6. Valvulopathy consistent with endocarditis in an Argentine boa (Boa constrictor occidentalis).

    PubMed

    Wernick, Morena B; Novo-Matos, José; Ebling, Alessia; Kühn, Karolin; Ruetten, Maja; Hilbe, Monika; Howard, Judith; Chang, Rita; Prohaska, Sarah; Hatt, Jean-Michel

    2015-03-01

    An Argentine boa (Boa constrictor occidentalis) of 5 yr 7 mo of age was presented for respiratory problems and regurgitation. Radiographs revealed evidence of cardiomegaly and pneumonia. Blood smear examination revealed the presence of intracytoplasmic inclusion bodies in peripheral lymphocytes, consistent with inclusion body disease. Cultures of a tracheal wash sample resulted in growth of Ochrobactrum intermedium and Pseudomonas putida. Echocardiographic examination revealed a large vegetative lesion on the right atrioventricular valve with valvular insufficiency, a mildly dilated right atrium, and pulmonary hypertension. Postmortem examination confirmed the presence of pneumonia and bacterial endocarditis with dystrophic mineralization of the right atrioventricular valve, associated with different bacteria than those cultured from the tracheal wash. The present case is the first report of endocarditis in a boa constrictor and contributes to the rare reports of cardiac disease in snakes. PMID:25831585

  7. Effects of clouds on erythemal and total irradiance as derived from data of the Argentine Network

    NASA Astrophysics Data System (ADS)

    Cede, Alexander; Blumthaler, Mario; Luccini, Eduardo; Piacentini, Rubén D.; Nuñez, Liliana

    2002-12-01

    Ultraviolet (UV) erythemal and total (300-3000 nm) irradiance measurements of the Argentine Servicio Meteorológico Nacional Network were related to ground-based cloud observations. No geographical dependence was observed in the effects of each cloud-type on the irradiance, from tropical to Antarctic regions. For overcast conditions, median transmittance percentages with respect to the clearsky situation of 81%, 44% and 36% at high, medium and low clouds respectively for erythemal irradiance, and 83%, 30% and 23% for total irradiance were determined, similar to results at mid-latitudes of the Northern Hemisphere. Irradiance enhancement by broken cloud fields is more pronounced from 5 to 7 octas cloud coverage and can last even hours, with peak instantaneous values of 113% for erythemal and 133% for total irradiance, with respect to the very clean clearsky situation. In each case, the total irradiance is usually more attenuated and also more enhanced by clouds than the erythemal irradiance.

  8. Calibration and uncertainty estimation of erythemal radiometers in the Argentine Ultraviolet Monitoring Network

    NASA Astrophysics Data System (ADS)

    Cede, Alexander; Luccini, Eduardo; Nunez, Liliana; Piacentini, Ruben D.; Blumthaler, Mario

    2002-10-01

    The erythemal radiometers of the Ultraviolet Monitoring Network of the Argentine Servicio Meteorologico Nacional were calibrated in an extensive in situ campaign from October 1998 to April 1999 with Austrian reference instruments. Methods to correct the influence of the location's horizon and long-term detector changes are applied. The different terms that contribute to the measurement uncertainty are analyzed. The expanded uncertainty is estimated to be plus-or-minus10% at 70deg solar zenith angle (SZA) and plus-or-minus6% for a SZA of <50deg. We observed significant changes for some detectors over hours and days, reaching a maximum diurnal drift of plus-or-minus5% at a SZA of 70deg and a maximum weekly variation of plus-or-minus4%.

  9. Adjective checklist to assess the big five personality factors in the Argentine population.

    PubMed

    Ledesma, Rubén D; Sánchez, Roberto; Díaz-Lázaro, Carlos M

    2011-01-01

    The aim of this work was to develop an adjective checklist to assess the Big Five personality factors in the Argentine population. The new instrument was administered to pilot (n= 112), validation (n= 372), and replication (n= 309) samples. The final version of the checklist included 67 adjectives encompassing its 5 dimensions. Factor analysis results were consistent with the Five-factor model. Internal consistency of scales was very good and convergent correlations with the Big Five Inventory (BFI; John, Donahue, & Kentle, 1991) were substantial. Face validity, as evaluated by 2 independent raters, was good. Preliminary evidence of validity for the checklist is presented. Finally, the Adjective Checklist for Personality Assessment and BFI are compared, taking into consideration their psychometric properties in our cultural context. Study limitations and future research are discussed. PMID:21184330

  10. Floral visitation by the Argentine ant reduces bee visitation and plant seed set.

    PubMed

    Hanna, Cause; Naughton, Ida; Boser, Christina; Alarcón, Ruben; Hung, Keng-Lou James; Holway, David

    2015-01-01

    Ants often visit flowers, but have only seldom been documented to provide effective pollination services. Floral visitation by ants can also compromise plant reproduction in situations where ants interfere with more effective pollinators. Introduced ants may be especially likely to reduce plant reproductive success through floral visitation, but existing experimental studies have found little support for this hypothesis. Here, we combine experimental and observational approaches to examine the importance of floral visitation by the nonnative Argentine ant (Linepithema humile) on plant species native to Santa Cruz Island, California, USA. First, we determine how L. humile affects floral visitor diversity, bee visitation rates, and levels of pollen limitation for the common, focal plant species island morning glory (Calystegia macrostegia ssp. macrostegia). Second, we assess the broader ecological consequences of floral visitation by L. humile by comparing floral visitation networks between invaded and uninvaded sites. The Argentine ant and native ants both visited island morning glory flowers, but L. humile was much more likely to behave aggressively towards other floral visitors and to be the sole floral occupant. The presence of L. humile in morning glory flowers reduced floral visitor diversity, decreased rates of bee visitation, and increased levels of pollen limitation. Network comparisons between invaded and uninvaded. sites revealed differences in both network structure and species-level attributes. In. invaded sites, floral visitors were observed on fewer plant species, ants had a higher per-plant interaction strength relative to that of other visitors, and interaction strengths between bees and plants were weaker. These results illustrate that introduced ants can negatively affect plant reproduction and potentially disrupt pollination services at an ecosystem scale. PMID:26236907

  11. First finding of melanic sylvatic Triatoma infestans (Hemiptera: Reduviidae) colonies in the Argentine Chaco.

    PubMed

    Ceballos, L A; Piccinali, R V; Berkunsky, I; Kitron, U; Gürtler, R E

    2009-09-01

    Triatoma infestans (Klug), the most important vector of Chagas disease in southern South America, is a highly domiciliated species with well-known sylvatic foci only in the Bolivian Andean valleys and in the Bolivian Chaco, where melanic insects designated as "dark morphs" were found. After the tentative identification of two melanic bugs collected from parrot nests in a forest reserve in the Argentine Chaco as T. infestans, we conducted an intensive search there using mouse-baited sticky traps in summer 2006 and 2007. Four live T. infestans bugs were collected in trees without parrot nests in 288 trap-nights, whereas no bug was collected from inside trees with active parrot nests in 51 trap-nights. To increase bug captures, hollow tree trunks that recently had had Amazona aestiva (Berlepsch) and Aratinga acuticaudata (Vieillot) parrot nests were treated with insecticide fumigant canisters exhibiting strong knockdown power. Four (22%) of 18 trees were positive for T. infestans with a dark phenotype. A fragment of the mitochondrial gene COI of 8 of the 14 triatomine bugs collected was successfully sequenced and confirmed as T. infestans. Most of the bugs were captured from Aspidosperma quebracho-blanco (Schlechter) hollow tree trunks harboring parrot nests. All of the T. infestans collected from the nearest house located at 10 km from the sylvatic foci displayed normal chromatic characters. The repeated finding of T. infestans in sylvatic habitats, albeit at very low density, shows that this species is capable of maintaining viable sylvatic foci in the absence of human hosts and immigration from domestic populations. These are the first confirmed findings of sylvatic T. infestans colonies in Argentina and of dark morphs in the Argentine Chaco. PMID:19769054

  12. Marine fronts are important fishing areas for demersal species at the Argentine Sea (Southwest Atlantic Ocean)

    NASA Astrophysics Data System (ADS)

    Alemany, Daniela; Acha, Eduardo M.; Iribarne, Oscar O.

    2014-03-01

    The high primary and secondary production associated with frontal systems attract a diversity of organisms due to high prey availability; this is why a strong relationship between fronts and pelagic fisheries has been shown worldwide. In the Argentine Sea, demersal resources are the most important, both in economical and in ecological sense; so we hypothesize that fronts are also preferred fishing areas for demersal resources. We evaluated the relationship between spatial distribution of fishing effort and oceanographic fronts, analyzing three of the most important frontal systems located in the Argentine Sea: the shelf-break front, the southern Patagonia front and the mid-shelf front. Individual vessel satellite monitoring system data (VMS; grouped by fleet type: ice-trawlers, freezer-trawlers and jigging fleet) were studied and fishing events were identified. Fishing events per area were used as a proxy of fishing effort and its spatial distribution by fleet type was visualized and analyzed with Geographic Information Systems. Oceanographic fronts were defined using polygons based on satellite chlorophyll amplitude values, and the percentage of fishing events within each polygon was calculated. Results showed a positive association between fronts and fishing activities of the different fleets, which suggests the aggregation of target species in these zones. The coupling of the freezer-trawler and jigging fleets (that operate on lower trophic level species; Macruronus magellanicus and Illex argentinus respectively) with fronts was higher than the ice-trawler fleet, targeting species of higher trophic level (Merluccius hubbsi). Marine fronts represent important fishing areas, even for demersal resources, as the distribution of fishing fleets and fishing effort are positively associated with frontal zones.

  13. Development of virtual bait stations to control Argentine ants (Hymenoptera: Formicidae) in environmentally sensitive habitats.

    PubMed

    Choe, Dong-Hwan; Vetter, Richard S; Rust, Michael K

    2010-10-01

    A novel bait station referred to as a virtual bait station was developed and tested against field populations of the invasive Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), at White Beach, Camp Pendleton, in Oceanside, CA. White Beach is a nesting habitat for an endangered seabird, the California least tern (Sterna antillarum browni Mearns). The beach is heavily infested with Argentine ants, one of the threats for the California least tern chicks. Conventional pest control strategies are prohibited because of the existence of the protected bird species and the site's proximity to the ocean. The bait station consisted of a polyvinyl chloride pipe that was treated on the inside with fipronil insecticide at low concentrations to obtain delayed toxicity against ants. The pipe was provisioned with an inverted bottle of 25% sucrose solution, then capped, and buried in the sand. Foraging ants crossed the treated surface to consume the sucrose solution. The delayed toxicity of fipronil deposits allowed the ants to continue foraging on the sucrose solution and to interact with their nestmates, killing them within 3-5 d after exposure. Further modification of the bait station design minimized the accumulation of dead ants in the sucrose solution, significantly improving the longevity and efficacy of the bait station. The virtual bait station exploits the foraging behavior of the ants and provides a low impact approach to control ants in environmentally sensitive habitats. It excluded all insects except ants, required only milligram quantities of toxicant, and eliminated the problem of formulating toxicants into aqueous sugar baits. PMID:21061977

  14. Improving liquid bait programs for Argentine ant control: bait station density.

    PubMed

    Nelson, Erik H; Daane, Kent M

    2007-12-01

    Argentine ants, Linepithema humile (Mayr), have a positive effect on populations of mealybugs (Pseudococcus spp.) in California vineyards. Previous studies have shown reductions in both ant activity and mealybug numbers after liquid ant baits were deployed in vineyards at densities of 85-620 bait stations/ha. However, bait station densities may need to be <85 bait stations/ha before bait-based strategies for ant control are economically comparable to spray-based insecticide treatments-a condition that, if met, will encourage the commercial adoption of liquid baits for ant control. This research assessed the effectiveness of baits deployed at lower densities. Two field experiments were conducted in commercial vineyards. In experiment 1, baits were deployed at 54-225 bait stations/ha in 2005 and 2006. In experiment 2, baits were deployed at 34-205 bait stations/ha in 2006 only. In both experiments, ant activity and the density of mealybugs in grape fruit clusters at harvest time declined with increasing bait station density. In 2005 only, European fruit lecanium scale [Parthenolecanium corni (Bouché)] were also present in fruit clusters, and scale densities were negatively related to bait station density. The results indicate that the amount of ant and mealybug control achieved by an incremental increase in the number of bait stations per hectare is constant across a broad range of bait station densities. The results are discussed in the context of commercializing liquid ant baits to provide a more sustainable Argentine ant control strategy. PMID:18284776

  15. Can the Argentine ant ( Linepithema humile Mayr) replace native ants in myrmecochory?

    NASA Astrophysics Data System (ADS)

    Gómez, Crisanto; Oliveras, Jordi

    2003-04-01

    We analyse the influence of the Argentine ant ( Linepithema humile Mayr) on the seed dispersal process of the myrmecochorous plants Euphorbia characias, E. biumbellata, Genista linifolia, G. triflora, G. monspessulana and Sarothamnus arboreus. The observations were made in two study plots of Mediterranean cork-oak secondary forest (invaded and non-invaded by L. humile). The presence of L. humile implies the displacement of all native ant species that disperse seeds. Seed transports in the non-invaded zone were carried out by eight ant species. In the invaded zone, L. humile workers removed and transported seeds to the nest. In vertebrate exclusion trials, we observed the same level of seed removal in the invaded and non-invaded zones. Two findings could explain this result. Although mean time to seed localization was higher for native ants (431.7 s) than that for L. humile (150.5 s), the mean proportion of seeds transported after being detected was higher (50.1%) in non-invaded than in invaded (16.8%) zones. The proportion of seeds removed and transported into an ant nest after an ant-seed interaction had dramatically reduced from non-invaded (41.9%) to invaded (7.4%) zones. The levels of seed dispersal by ants found prior to invasion are unlikely to be maintained in invaded zones. However, total replacement of seed dispersal function is possible if contact iteration finally offers similar levels or quantities of seeds reaching the nests. The results obtained confirm that the Argentine ant invasion may affect myrmecochory dramatically in the Mediterranean biome.

  16. First Finding of Melanic Sylvatic Triatoma infestans (Hemiptera: Reduviidae) Colonies in the Argentine Chaco

    PubMed Central

    CEBALLOS, L. A.; PICCINALI, R. V.; BERKUNSKY, I.; KITRON, U.; GÜRTLER, R. E.

    2009-01-01

    Triatoma infestans (Klug), the most important vector of Chagas disease in southern South America, is a highly domiciliated species with well-known sylvatic foci only in the Bolivian Andean valleys and in the Bolivian Chaco, where melanic insects designated as “dark morphs” were found. After the tentative identification of two melanic bugs collected from parrot nests in a forest reserve in the Argentine Chaco as T. infestans, we conducted an intensive search there using mouse-baited sticky traps in summer 2006 and 2007. Four live T. infestans bugs were collected in trees without parrot nests in 288 trap-nights, whereas no bug was collected from inside trees with active parrot nests in 51 trap-nights. To increase bug captures, hollow tree trunks that recently had had Amazona aestiva (Berlepsch) and Aratinga acuticaudata (Vieillot) parrot nests were treated with insecticide fumigant canisters exhibiting strong knockdown power. Four (22%) of 18 trees were positive for T. infestans with a dark phenotype. A fragment of the mitochondrial gene COI of 8 of the 14 triatomine bugs collected was successfully sequenced and confirmed as T. infestans. Most of the bugs were captured from Aspidosperma quebracho-blanco (Schlechter) hollow tree trunks harboring parrot nests. All of the T. infestans collected from the nearest house located at 10 km from the sylvatic foci displayed normal chromatic characters. The repeated finding of T. infestans in sylvatic habitats, albeit at very low density, shows that this species is capable of maintaining viable sylvatic foci in the absence of human hosts and immigration from domestic populations. These are the first confirmed findings of sylvatic T. infestans colonies in Argentina and of dark morphs in the Argentine Chaco. PMID:19769054

  17. Workers select mates for queens: a possible mechanism of gene flow restriction between supercolonies of the invasive Argentine ant

    NASA Astrophysics Data System (ADS)

    Sunamura, Eiriki; Hoshizaki, Sugihiko; Sakamoto, Hironori; Fujii, Takeshi; Nishisue, Koji; Suzuki, Shun; Terayama, Mamoru; Ishikawa, Yukio; Tatsuki, Sadahiro

    2011-05-01

    Some invasive ants form large networks of mutually non-aggressive nests, i.e., supercolonies. The Argentine ant Linepithema humile forms much larger supercolonies in introduced ranges than in its native range. In both cases, it has been shown that little gene flow occurs between supercolonies of this species, though the mechanism of gene flow restriction is unknown. In this species, queens do not undertake nuptial flight, and males have to travel to foreign nests and cope with workers before gaining access to alien queens. In this study, we hypothesized that male Argentine ants receive interference from workers of alien supercolonies. To test this hypothesis, we conducted behavioral and chemical experiments using ants from two supercolonies in Japan. Workers attacked males from alien supercolonies but not those from their own supercolonies. The level of aggression against alien males was similar to that against alien workers. The frequency of severe aggression against alien males increased as the number of recipient workers increased. Cuticular hydrocarbon profiles, which serve as cues for nestmate recognition, of workers and males from the same supercolony were very similar. Workers are likely to distinguish alien males from males of their own supercolony using the profiles. It is predicted that males are subject to considerable aggression from workers when they intrude into the nests of alien supercolonies. This may be a mechanism underlying the restricted gene flow between supercolonies of Argentine ants. The Argentine ant may possess a distinctive reproductive system, where workers participate in selecting mates for their queens. We argue that the aggression of workers against alien males is a novel form of reproductive interference.

  18. Floral visitation by the Argentine ant reduces pollinator visitation and seed set in the coast barrel cactus, Ferocactus viridescens.

    PubMed

    LeVan, Katherine E; Hung, Keng-Lou James; McCann, Kyle R; Ludka, John T; Holway, David A

    2014-01-01

    Mounting evidence indicates that trade-offs between plant defense and reproduction arise not only from resource allocation but also from interactions among mutualists. Indirect costs of plant defense by ants, for example, can outweigh benefits if ants deter pollinators. Plants can dissuade ants from occupying flowers, but such arrangements may break down when novel ant partners infiltrate mutualisms. Here, we examine how floral visitation by ants affects pollination services when the invasive Argentine ant (Linepithema humile) replaces a native ant species in a food-for-protection mutualism with the coast barrel cactus (Ferocactus viridescens), which, like certain other barrel cacti, produces extrafloral nectar. We compared the effects of floral visitation by the Argentine ant with those of the most prevalent native ant species (Crematogaster californica). Compared to C. californica, the Argentine ant was present in higher numbers in flowers. Cactus bees (Diadasia spp.), the key pollinators in this system, spent less time in flowers when cacti were occupied by the Argentine ant compared to when cacti were occupied by C. californica. Presumably as a consequence of decreased duration of floral visits by Diadasia, cacti occupied by L. humile set fewer seeds per fruit and produced fewer seeds overall compared to cacti occupied by C. californica. These data illustrate the importance of mutualist identity in cases where plants balance multiple mutualisms. Moreover, as habitats become increasingly infiltrated by introduced species, the loss of native mutualists and their replacement by non-native species may alter the shape of trade-offs between plant defense and reproduction. PMID:23892582

  19. [Argentine migration policy and movements of the European population (1876-1925)].

    PubMed

    Devoto, F J

    1989-04-01

    This work examines changes in Argentine migration policy from 1876-1925 and the relationship between public policy and population movements. Promoting immigration from Europe as proposed in article 25 of the Argentine constitution of 1853 was 1 of the most enduring objectives of Argentina's leadership. When Law of Immigration and Colonization (Law 817) was passed by the Chamber of Senators in 1876, the flow of immigration was at its lowest point in 8 years. Many of the provisions of Law 817 had already been put into practice occasionally or systematically, but the intent to use the law to attract a far greater number of immigrants and to select qualities seen as desirable were novel elements and the principal motives of the legislation. The unstated aim of reducing the preponderance of Italian immigration from about 2/3 was not immediately achieved. Argentina's immigration policy and actions were in competition with those of other Latin American countries and with the US. Information offices for prospective immigrants were opened in the 1880s in Paris, London, Brussels, Berlin, Vienna, Bern, and New York, and in 1887 legislation was passed permitting subsidized passages on a large scale. The continued predominance of Italian immigration demonstrated the limits of government policy influence, even when large sums of money were invested. The informal network of Italian immigrants already in Argentina and the activities of interested shipping companies on the other hand played major roles in maintaining Italian immigration. The total number of immigrants and the diversity of national origins were increased by the subsidized passages, but in 1891 the combination of a financial crisis and an end to subsidized passages decisively reduced the total flow. Changes occurred in the 1890s in regional flows within countries and in the occupational composition of immigrants from agricultors to day laborers, unskilled workers, and artisans. By about 1910 the conservative elements

  20. Characterization of Argentine honeys on the basis of their mineral content and some typical quality parameters

    PubMed Central

    2014-01-01

    Background The levels of 19 elements (As, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Se, Tl, U, V, Zn) from sixteen different Argentine production sites of unifloral [eucalyptus (Eucaliptus rostrata), chilca (Baccharis salicifolia), Algarrobo (Prosopis sp.), mistol (Ziziphus mistol) and citric] and multifloral honeys were measured with the aim to test the quality of the selected samples. Typical quality parameters of honeys were also determined (pH, sugar content, moisture). Mineral elements were determined by using inductively coupled plasma mass spectrometer (ICP-MS DRC). We also evaluated the suitability of honey as a possible biomonitor of environmental pollution. Thus, the sites were classified through cluster analysis (CA) and then pattern recognition methods such as Principal Component Analysis (PCA) and discriminant analysis (DA) were applied. Results Mean values for quality parameters were: pH, 4.12 and 3.81; sugar 82.1 and 82.0 °brix; moisture, 16.90 and 17.00% for unifloral and multifloral honeys respectively. The water content showed good maturity. Likewise, the other parameters confirmed the good quality of the honeys analysed. Potassium was quantitatively the most abundant metal, accounting for 92,5% of the total metal contents with an average concentration of 832.0 and 816.2 μg g-1 for unifloral and multifloral honeys respectively. Sodium was the second most abundant major metal in honeys with a mean value of 32.16 and 33.19 μg g-1 for unifloral and multifloral honeys respectively. Mg, Ca, Fe, Mn, Zn and Cu were present at low-intermediate concentrations. For the other 11 trace elements determined in this study (As, Be, Cd, Co, Cr, Ni, Pb, Se, Tl, U and V), the mean concentrations were very low or below of the LODs. The sites were classified through CA by using elements’ and physicochemical parameters data, then DA on the PCA factors was applied. Dendrograms identified three main groups. PCA explained 52.03% of the total variability

  1. NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.; Zinn, W.H.; Anderson, H.L.

    1958-09-16

    Means are presenied for increasing the reproduction ratio of a gaphite- moderated neutronic reactor by diminishing the neutron loss due to absorption or capture by gaseous impurities within the reactor. This means comprised of a fluid-tight casing or envelope completely enclosing the reactor and provided with a valve through which the casing, and thereby the reactor, may be evacuated of atmospheric air.

  2. Argentine ant (Hymenoptera: Formicidae) trail pheromone enhances consumption of liquid sucrose solution.

    PubMed

    Greenberg, L; Klotz, J H

    2000-02-01

    We investigated whether the Argentine ant, Linepithema humile (Mayr), trail pheromone, Z9-16:Ald, could enhance recruitment to and consumption of liquid sucrose solutions. All tests were done as paired comparisons with a 10% sucrose solution as food. In the laboratory, mixing 20 microl of a 10-microg/ml solution of the pheromone with 50 microl of the 10% sucrose solution increased the number of ants feeding by >150%. In a field test, we combined the trail pheromone with a 10% sucrose solution in 50-ml vials. These vials were covered with a plastic membrane that has 1.5-mm-diameter holes punched uniformly across its surface. Ants could drink from the holes after the vials were inverted. For half of the vials, 1 microg of the pheromone was put onto the plastic membrane before the vials were filled with a 10% sucrose solution. The remaining vials had no pheromone on the plastic membrane. After 4 h we measured the consumption in each vial. Bait consumption with the pheromone was enhanced by 29%. In a 2nd series of tests, vials were left outside for 24 h. The consumption rate was 33% higher with the pheromone compared with the controls that didn't have pheromone. PMID:14658521

  3. Diet and genotype effects on the quality index of beef produced in the Argentine Pampeana region.

    PubMed

    Latimori, N J; Kloster, A M; García, P T; Carduza, F J; Grigioni, G; Pensel, N A

    2008-07-01

    Steers of varying genotypes (Aberdeen Angus, Charolais x AA and Argentine Holstein) in four feeding systems were evaluated. Feeding systems were: S1=a diet based on pastures only; S2=a similar forage base as S1 plus a daily supplementation with cracked corn, at 0.7% of l.w./head/day; S3=a similar forage base as S1 plus a daily supplementation with cracked corn, at 1.0% of l.w./head/day; and S4=a regular feedlot diet. Tenderness and marbling were not affected by the feeding system. Feedlot meat showed an n-6/n-3 ratio significantly higher than meat produced with the diets based on pastures (S1=2.1; S2=3.1; S3=4.5; S4=14.2) (P<0.05), whereas CLA content had an inverse behavior, showing S1 (0.67%) and S2 (0.64%) higher concentrations than S3 (0.55%) and S4 (0.28%) (P<0.05). Diet based on pastures plus a low level of supplementation produced meat with better nutritional characteristics than other productive alternatives, without significant effects of the biotypes. PMID:22062907

  4. Argentines' collective memories of the military Junta of 1976: differences and similarities across generations and ideology.

    PubMed

    Muller, Felipe; Bermejo, Federico; Hirst, William

    2016-08-01

    Although memories about a nation's past usually are semantic in nature, a distinction needs to be made between lived and distant semantic collective memories. The former refers to memories of community-relevant events occurring during the lifetime of the rememberer, whereas the latter to memories of distant events. Does the content of lived and distant semantic collective memories differ? Employing both free and cued recall, we examined the memories of younger and older Argentines of the Military Junta of 1976. We also examined the effects of political ideology. Content analysis indicated that (1) lived semantic collective memories were more likely to contain personal recollections than distant semantic collective memories, even though those with distant semantic collective memories could have incorporated memories of the parent's personal experience in their recollections, (2) lived semantic collective memories contained more causal statements, and (3) those on the Right with distant semantic collective memories were more likely to claim that they "Don't know" or offer positive accounts of the Junta, suggesting a need to "defend" the reputation of those on the Right. The results are discussed in terms of the goals and plans different generations might have when recollecting their nation's past. PMID:26293779

  5. Chemical Defense by the Native Winter Ant (Prenolepis imparis) against the Invasive Argentine Ant (Linepithema humile)

    PubMed Central

    Kauhanen, Peter G.; Fitzgerald, Katherine; Sturgis, Shelby J.; Chen, Jimmy; Dijamco, Cheri A.; Basurto, Kimberly N.; Gordon, Deborah M.

    2011-01-01

    The invasive Argentine ant (Linepithema humile) is established worldwide and displaces native ant species. In northern California, however, the native winter ant (Prenolepis imparis) persists in invaded areas. We found that in aggressive interactions between the two species, P. imparis employs a potent defensive secretion. Field observations were conducted at P. imparis nest sites both in the presence and absence of L. humile. These observations suggested and laboratory assays confirmed that P. imparis workers are more likely to secrete when outnumbered by L. humile. Workers of P. imparis were also more likely to secrete near their nest entrances than when foraging on trees. One-on-one laboratory trials showed that the P. imparis secretion is highly lethal to L. humile, causing 79% mortality. The nonpolar fraction of the secretion was chemically analyzed with gas chromatography/mass spectrometry, and found to be composed of long-chain and cyclic hydrocarbons. Chemical analysis of dissected P. imparis workers showed that the nonpolar fraction is derived from the Dufour's gland. Based on these conclusions, we hypothesize that this chemical defense may help P. imparis to resist displacement by L. humile. PMID:21526231

  6. Characterization of pectinase activity for enology from yeasts occurring in Argentine Bonarda grape.

    PubMed

    Merín, María Gabriela; Martín, María Carolina; Rantsiou, Kalliopi; Cocolin, Luca; de Ambrosini, Vilma Inés Morata

    2015-01-01

    Pectinolytic enzymes are greatly important in winemaking due to their ability to degrade pectic polymers from grape, contributing to enhance process efficiency and wine quality. This study aimed to analyze the occurrence of pectinolytic yeasts during spontaneous fermentation of Argentine Bonarda grape, to select yeasts that produce extracellular pectinases and to characterize their pectinolytic activity under wine-like conditions. Isolated yeasts were grouped using PCR-DGGE and identified by partial sequencing of 26S rRNA gene. Isolates comprised 7 genera, with Aureobasidium pullulans as the most predominant pectinolytic species, followed by Rhodotorula dairenensis and Cryptococcus saitoi. No pectinolytic activity was detected among ascomycetous yeasts isolated on grapes and during fermentation, suggesting a low occurrence of pectinolytic yeast species in wine fermentation ecosystem. This is the first study reporting R. dairenensis and Cr. saitoi species with pectinolytic activity. R. dairenensis GM-15 produced pectinases that proved to be highly active at grape pH, at 12 °C, and under ethanol and SO2 concentrations usually found in vinifications (pectinase activity around 1.1 U/mL). This strain also produced cellulase activity at 12 °C and pH 3.5, but did not produce β-glucosidase activity under these conditions. The strain showed encouraging enological properties for its potential use in low-temperature winemaking. PMID:26413065

  7. Characterization of an Argentine isolate of Bacillus thuringiensis similar to the HD-1 strain.

    PubMed

    Sauka, Diego H; Basurto-Ríos, Regina E; Ibarra, Jorge E; Benintende, Graciela B

    2010-01-01

    We report the characterization of an Argentine isolate of Bacillus thuringiensis (INTA TA24-6) similar to the HD-1 strain, which harbors a cryptic cry2Ab gene that apparently is transcribed but not translated into a protein. INTA TA24-6 showed a Rep-PCR pattern identical to the HD-1 strain, a plasmid pattern that resembled that of this strain and cry1 and cry2 genes as HD-1. Screening of cry1 and cry2 genes showed that INTA TA24-6 harbors only cry1Ac and cry2Ab genes. Furthermore, crystalline inclusions of INTA TA24-6 exhibit a bipyramidal shape, typical of Lepidoptera-active B. thuringiensis strains, containing a major protein of ca. 130 kDa toxic to Epinotia aporema Wals. (Lepidoptera: Tortricidae) larvae. Neither the flat-square to cuboidal crystal nor a ca. 65 kDa protein typical of strains expressing Cry2 proteins were detected in INTA TA24-6. In agreement with this information, parasporal crystals of INTA TA24-6 did not show toxicity to Aedes aegypti L. (Diptera:Culicidae) larvae. Gene transcription analyses suggested that the cry2A gene might be cryptic in INTA TA24-6 despite its transcription at different sporulation stages. PMID:21120387

  8. Characterization of pectinase activity for enology from yeasts occurring in Argentine Bonarda grape

    PubMed Central

    Merín, María Gabriela; Martín, María Carolina; Rantsiou, Kalliopi; Cocolin, Luca; de Ambrosini, Vilma Inés Morata

    2015-01-01

    Pectinolytic enzymes are greatly important in winemaking due to their ability to degrade pectic polymers from grape, contributing to enhance process efficiency and wine quality. This study aimed to analyze the occurrence of pectinolytic yeasts during spontaneous fermentation of Argentine Bonarda grape, to select yeasts that produce extracellular pectinases and to characterize their pectinolytic activity under wine-like conditions. Isolated yeasts were grouped using PCR-DGGE and identified by partial sequencing of 26S rRNA gene. Isolates comprised 7 genera, with Aureobasidium pullulans as the most predominant pectinolytic species, followed by Rhodotorula dairenensis and Cryptococcus saitoi. No pectinolytic activity was detected among ascomycetous yeasts isolated on grapes and during fermentation, suggesting a low occurrence of pectinolytic yeast species in wine fermentation ecosystem. This is the first study reporting R. dairenensis and Cr. saitoi species with pectinolytic activity. R. dairenensis GM-15 produced pectinases that proved to be highly active at grape pH, at 12 °C, and under ethanol and SO2 concentrations usually found in vinifications (pectinase activity around 1.1 U/mL). This strain also produced cellulase activity at 12 °C and pH 3.5, but did not produce β-glucosidase activity under these conditions. The strain showed encouraging enological properties for its potential use in low-temperature winemaking. PMID:26413065

  9. Transfer of the Argentine Precordillera terrane from Laurentia: Constraints from detrital-zircon geochronology

    USGS Publications Warehouse

    Thomas, W.A.; Astini, R.A.; Mueller, P.A.; Gehrels, G.E.; Wooden, J.L.

    2004-01-01

    Ages from U-Pb and 207Pb/206Pb analyses of detrital zircons from synrift sandstone in the Lower Cambrian Cerro Totora Formation of the Argentine Precordillera have strong similarities to those from late synrift sandstones in the Lower Cambrian Rome Formation of southern Laurentia (Alabama). Ages of detrital zircons from the Cerro Totora sample cluster at 1160-970 Ma (60% of analyzed zircons , 1490-1300 Ma (24%), and 1890-1640 Ma (16%). Ages from two Rome samples cluster at 1240-970 Ma (32% of analyzed zircons), 1540-1270 Ma (31%), 1840-1610 Ma (14%), 1970-1890 Ma (5%), and 2930-2310 Ma (18%). The ages of detrital zircons from the Rome and Cerro Totora sandstones are consistent with sediment supply from the Grenville and older Proterozoic Laurentian provinces, and the older cluster in the Rome sandstones corresponds in age to the Laurentian Archean Superior province. Neither the Rome nor Cerro Totora samples include components younger than Grenville, and the lack of zircons from distinctly Gondwanan provinces is consistent with a Laurentian provenance. The detrital-zircon ages support previous interpretations that the Precordillera was rifted from the Ouachita embayment of Laurentia during Early Cambrian time and subsequently was transferred to Gondwana. ?? 2004 Geological Society of America.

  10. Repaired shell damage in the commercial scallop Zygochlamys patagonica (King & Broderip, 1832), Argentine Sea

    NASA Astrophysics Data System (ADS)

    Schejter, Laura; Bremec, Claudia

    2007-08-01

    We present an overview of repaired shell damage in the scallop Zygochlamys patagonica in the commercial beds of the Argentine Sea. Presence of scars was registered in 11 962 scallops, ranging from 20 to 90 mm total height, from the fishing grounds in 2003 and also in 1995 (pre-fishery condition). Values of percentage of scarring (presence) were variable in all areas. Samples collected in 1995 showed the highest percentage of scars. As the highest records of scarring were registered in pre-fishery conditions, it is not possible to regard these marks as absolute indicators of anthropogenic disturbance caused by trawling activities. Moderate and severe damage was mostly recorded in individuals of commercial size (≥ 55 mm). This indicates not only the fragility of smaller scallops, but also the accumulation of damage in older specimens, probably more resistant to damage because of their thicker shells. The selective removal of commercial individuals could explain in part our results that indicate a higher percentage of repaired shell damage in 1995, when the average size of the population was also higher. Future investigations are needed to assess effects of scarring at different shell sizes (ages) and relate these to levels of survival in Patagonian scallops thrown back into the sea during processing on board.

  11. Chromosomal variation in Argentine populations of Akodon montensis Thomas, 1913 (Rodentia, Cricetidae, Sigmodontinae)

    PubMed Central

    Malleret, Matías Maximiliano; Labaroni, Carolina Alicia; García, Gabriela Verónica; Ferro, Juan Martín; Martí, Dardo Andrea; Lanzone, Cecilia

    2016-01-01

    Abstract The genus Akodon Meyen, 1833 is one of the most species-rich among sigmodontine rodents and has great chromosome variability. Akodon montensis has a relatively broad distribution in South America, and Argentine populations are located in the southernmost region of its range. Brazilian populations have important chromosomal variability, but cytogenetic data from Argentina are scarce. We performed a chromosome characterization of natural populations of Akodon montensis using conventional staining, C-banding, Ag-NORs and base-specific fluorochromes. A total of 31 specimens from five localities of Misiones Province, in Argentina, were analyzed. The 2n=24 chromosomes was the most frequently observed karyotype. However, five individuals presented 25 chromosomes due to a supernumerary B-chromosome; and one individual had 2n=26 due to one B plus a trisomy for chromosome 11. Additionally, two XY females and two variants of the X chromosomes were found. C-positive centromeric bands occurred in all chromosomes; additional C-bands were observed in some autosomes, the X, Y and B chromosomes. Ag-NORs were observed in five autosomes, and the B chromosome was frequently marked. Fluorochrome banding was similar among karyotypes of the analyzed populations. Comparisons of cytogenetic data among populations of Argentina and Brazil showed the presence of high intraspecific variability in Akodon montensis and some differences among regions. PMID:27186343

  12. Effect of Temperature on the Development and Survival of the Argentine Ant, Linepithema humile

    PubMed Central

    Abril, Silvia; Oliveras, Jordi; Gómez, Crisanto

    2010-01-01

    The influence of temperature on the developmental times and survival of insects can largely determine their distribution. For invasive species, like the Argentine ant, Linepithema humile Mayr (Hymenoptera: Formicidae), these data are essential for predicting their potential range based on mechanistic models. In the case of this species, such data are too scarce and incomplete to make accurate predictions based on its physiological needs. This research provides comprehensive new data about brood survival and developmental times at a wide range of temperatures under laboratory conditions. Temperature affected both the complete brood development from egg to adult worker and each of the immature stages separately. The higher the temperature, the shorter the development times. Brood survival from egg to adult was low, with the maximum survival rate being only 16% at 26° C. Temperature also affected survival of each of the immature stages differently: eggs were negatively affected by high temperatures, while larvae were negatively affected by low temperatures, and the survival of pupae was apparently independent of environmental temperature. At 32° C no eggs survived, while at 18° C less than 2% of the eggs hatched into larva. The data from the present study are essential for developing prediction models about the distribution range of this tramp species based on its physiological needs in relation to temperature. PMID:20673121

  13. The role of abiotic conditions in shaping the long-term patterns of a high-elevation Argentine ant invasion

    USGS Publications Warehouse

    Krushelnycky, P.D.; Joe, S.M.; Medeiros, A.C.; Daehler, C.C.; Loope, L.L.

    2005-01-01

    Analysis of long-term patterns of invasion can reveal the importance of abiotic factors in influencing invasion dynamics, and can help predict future patterns of spread. In the case of the invasive Argentine ant (Linepithema humile), most prior studies have investigated this species' limitations in hot and dry climates. However, spatial and temporal patterns of spread involving two ant populations over the course of 30 years at a high elevation site in Hawaii suggest that cold and wet conditions have influenced both the ant's distribution and its rate of invasion. In Haleakala National Park on Maui, we found that a population invading at lower elevation is limited by increasing rainfall and presumably by associated decreasing temperatures. A second, higher elevation population has spread outward in all directions, but rates of spread in different directions appear to have been strongly influenced by differences in elevation and temperature. Patterns of foraging activity were strongly tied to soil temperatures, supporting the hypothesis that variation in temperature can influence rates of spread. Based on past patterns of spread, we predicted a total potential range that covers nearly 50% of the park and 75% of the park's subalpine habitats. We compared this rough estimate with point predictions derived from a degree-day model for Argentine ant colony reproduction, and found that the two independent predictions match closely when soil temperatures are used in the model. The cold, wet conditions that have influenced Argentine ant invasion at this site are likely to be influential at other locations in this species' current and future worldwide distribution. ?? 2005 Blackwell Publishing Ltd.

  14. Influence of toxic bait type and starvation on worker and queen mortality in laboratory colonies of Argentine ant (Hymenoptera: Formicidae).

    PubMed

    Mathieson, Melissa; Toft, Richard; Lester, Philip J

    2012-08-01

    The efficacy of toxic baits should be judged by their ability to kill entire ant colonies, including the colony queen or queens. We studied the efficacy of four toxic baits to the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae). These baits were Xstinguish that has the toxicant fipronil, Exterm-an-Ant that contains both boric acid and sodium borate, and Advion ant gel and Advion ant bait arena that both have indoxacarb. Experimental nests contained 300 workers and 10 queen ants that were starved for either 24 or 48 h before toxic bait exposure. The efficacy of the toxic baits was strongly influenced by starvation. In no treatment with 24-h starvation did we observe 100% worker death. After 24-h starvation three of the baits did not result in any queen deaths, with only Exterm-an-Ant producing an average of 25% mortality. In contrast, 100% queen and worker mortality was observed in colonies starved for 48 h and given Xstinguish or Exterm-an-Ant. The baits Advion ant gel and Advion ant bait arena were not effective against Argentine ants in these trials, resulting in <60% mortality in all treatments. Because of the strong influence of starvation on bait uptake, control efficacy may be maximized by applying bait when ants are likely to be starved. Our results suggest queen mortality must be assessed in tests for toxic bait efficacy. Our data indicate that of these four baits, Xstinguish and Exterm-an-Ant are the best options for control of Argentine ants in New Zealand. PMID:22928290

  15. The Argentine Impact Record: Implications for Episodes of Increased Flux during the Last 10 Myr

    NASA Astrophysics Data System (ADS)

    Harris, R. S.; Schultz, P. H.

    2009-12-01

    Schultz et al. [1-6] have identified 8 impact melt breccia deposits in late Cenozoic strata of the Argentine Pampas. 40Ar/39Ar and fission track dating, combined with sequence and biostratigraphic controls, demonstrate that they represent separate events between 9.24 Ma and 6 ka. These ejecta contain shocked minerals and excavated basement clasts indicative of crater-forming events rather than air blasts. If each involved iron bolides ≤ 50 m across, 8 impacts over ~1.1 x 106 km2 in 10 Myr does not represent an anomaly. However, the melt volumes and distributions observed suggest at least half of the collisions were much larger. One event close to the Miocene-Pliocene boundary (5.28 Ma) appears to have spread microtektites as far as the South Tasman Rise. And three deposits contain meteoritic debris linked to stony and stony-iron asteroids (including HED and angrite-like material) [6,7]. Consequently, one or more increases in the impact flux since the mid-Miocene may be required to account for the Argentine record [8]. Farley et al. [9,10] propose that the disruption of a large main-belt asteroid 8.3 Ma increased the IDP flux in the inner solar system leading to a positive 3He anomaly in late Miocene (~6.8-8.3 Ma) sediments. The anomaly is comparable to the late Eocene (~34.2-36.4 Ma) 3He enhancement attributed to a comet [11] or asteroid [12] shower, which increased both the abundance of IDPs and large asteroids reaching the surface. But Farley et al. discount such a scenario in the late Miocene based on a perceived absence of coincident crater-forming impacts. Preserved ejecta and geochemical signatures, however, indicate the contrary. We suggest that the late Miocene contains at least as rich a record of terrestrial impacts as the late Eocene. The patterns of elevated 3He, main-belt breakups, and significant impact events are very similar through both intervals. Two reported asteroid breakups during the Pliocene and mid-Pleistocene [13,14] also appear to

  16. Giant mudwaves in the Northern Argentine Basin: born and buried by bottom currents

    NASA Astrophysics Data System (ADS)

    Borisov, Dmitrii; Murdmaa, Ivar; Ivanova, Elena; Levchenko, Oleg

    2014-05-01

    New sedimentary records and very high resolution seismic profiles collected during four cruises of the RV "Akademik Ioffe" (2011-2013) were correlated with seismic, multibeam and coring data obtained during cruises of the RV "Robert Conrad", "Knorr", "Meteor". A complex analysis of the geological-geophysical data revealed an extensive field of giant mudwaves (48 000 km2) in the northwestern Argentine Basin, South Atlantic. The symmetric waves up to 60 m in height and 4000 m in wavelength are oriented roughly parallel to contours. They partly cover the Santa Catarina Plateau and extend through the Santos Basin to the Sao Paulo Plateau. The mudwaves field is traced at the depth range from 3400 to 4000 m and divided into buried (northern) and non-buried (southern) parts. The non-buried sediment waves cover the surface of the huge drift in the Santa Catarina Plateau. The wave height increases from the drift summit to its flanks and decreases at the foot. Two cores retrieved from the drift top and its northern flank recovered muddy contourites with a greater amount of silt-size material in the core from the drift flank. The age of the recovered sediments is at least 130 ka. In the northern Santos basin, the sediment waves are buried under a large lens-like sediment body (drift?) inclined at the margins. Cores obtained from the buried part of the mudwaves field recovered an intercalation of hemipelagic clay and silty-clay contourite. The age of recovered sediments does not exceed 150 ka (Bleil et al., 1993). Contourites deposition in the study area is related to the activity of the Antarctic bottom water (AABW) contour current. The AABW flow is considered to be divided into two branches by the Santa Catarina Plateau. We suggest that this topographic obstacle causes a flow velocity increase. Wave height and grain-size variations indicate higher bottom current velocities at the plateau flanks and relative tranquil conditions at the flat summit of the plateau. The symmetric

  17. [Suitability of wild underexploited vegetables from the Argentine Chaco as a food resource].

    PubMed

    Freyre, M R; Baigorria, C M; Rozycki, V R; Bernardi, C M; Charpentier, M

    2000-12-01

    The nutritional value of wild underexploited vegetable samples collected in the Argentine Chaco was investigated. Leaves from Hipochaeris sp.-, Coronopus didimus and Portulaca olearacea; fruits from Zyziphus sativa, Brumelia obtusifolia and Eugenia uniflora; and roots of Canna coccinea were included in this work; several separate samples being taken at least during two consecutive harvesting seasons. Values for moisture, protein, total lipids, crude fiber, ash, reducing and total sugars, starch, total pectins and energy are given. Mineral micronutrient contents are reported for calcium, potassium, magnesium, iron and phosphorus, as well as vitamin values (ascorbic acid and beta-carotene). Higher concentrations of macronutrients were found in the leafy vegetables (32-50 Kcal/100 g) than in commercially exploited cultivars (14-30 Kcal/100 g), as shown by an increased energy value, the protein content of Portulaca olearacea (3.74 g/100 g) being highly remarkable. Unusually high micronutrient figures were also determined in Coronopus didimus, with 172.3; 3.98, and 46.7 mg/100 g, for calcium, iron and magnesium, respectively. In general, fruits also showed higher macronutrient contents, with the exception of proteins, with less but constant values (1.58 to 1.74 g/100 g), although contributing more energy than commercial cultivars (70 to 147 Kcal/100 g). Equally important proved to be the provitamin A content in Eugenia uniflora (11.98 mg/100 g). Roots of Canna coccinea revealed the lowest energy value (34 Kcal/100 g) but surprisingly, the highest content of phosphorus of all the species under study. PMID:11464672

  18. Circadian analysis of myocardial infarction incidence in an Argentine and Uruguayan population

    PubMed Central

    D'Negri, Carlos E; Nicola-Siri, Leonardo; Vigo, Daniel E; Girotti, Luis A; Cardinali, Daniel P

    2006-01-01

    Background The occurrence of variations in the spectrum of cardiovascular disease between different regions of the world and ethnic groups have been the subject of great interest. This study report the 24-h variation of myocardial infarction (MI) occurrence in patients recruited from CCU located in Argentina and Uruguay. Methods A cohort of 1063 patients admitted to the CCU within 24 h of the onset of symptoms of an acute MI was examined. MI incidence along the day was computed in 1 h-intervals. Results A minimal MI incidence between 03:00 and 07:00 h and the occurrence of a first maximum between 08:00 and 12:00 h and a second maximum between 15:00 and 22:00 h were verified. The best fit curve was a 24 h cosinor (acrophase ~ 19:00 h, accounting for 63 % of variance) together with a symmetrical gaussian bell (maximum at ~ 10:00 h, accounting for 37 % of variance). A similar picture was observed for MI frequencies among different excluding subgroups (older or younger than 70 years; with or without previous symptoms; diabetics or non diabetics; Q wave- or non-Q wave-type MI; anterior or inferior MI location). Proportion between cosinor and gaussian probabilities was maintained among most subgroups except for older patients who had more MI at the afternoon and patients with previous symptoms who were equally distributed among the morning and afternoon maxima. Conclusion The results support the existence of two maxima (at morning and afternoon hours) in MI incidence in the Argentine and Uruguayan population. PMID:16401349

  19. Individual rules for trail pattern formation in Argentine ants (Linepithema humile).

    PubMed

    Perna, Andrea; Granovskiy, Boris; Garnier, Simon; Nicolis, Stamatios C; Labédan, Marjorie; Theraulaz, Guy; Fourcassié, Vincent; Sumpter, David J T

    2012-01-01

    We studied the formation of trail patterns by Argentine ants exploring an empty arena. Using a novel imaging and analysis technique we estimated pheromone concentrations at all spatial positions in the experimental arena and at different times. Then we derived the response function of individual ants to pheromone concentrations by looking at correlations between concentrations and changes in speed or direction of the ants. Ants were found to turn in response to local pheromone concentrations, while their speed was largely unaffected by these concentrations. Ants did not integrate pheromone concentrations over time, with the concentration of pheromone in a 1 cm radius in front of the ant determining the turning angle. The response to pheromone was found to follow a Weber's Law, such that the difference between quantities of pheromone on the two sides of the ant divided by their sum determines the magnitude of the turning angle. This proportional response is in apparent contradiction with the well-established non-linear choice function used in the literature to model the results of binary bridge experiments in ant colonies (Deneubourg et al. 1990). However, agent based simulations implementing the Weber's Law response function led to the formation of trails and reproduced results reported in the literature. We show analytically that a sigmoidal response, analogous to that in the classical Deneubourg model for collective decision making, can be derived from the individual Weber-type response to pheromone concentrations that we have established in our experiments when directional noise around the preferred direction of movement of the ants is assumed. PMID:22829756

  20. Feeding behavior and social interactions of the Argentine ant Linepithema humile change with sucrose concentration.

    PubMed

    Sola, F J; Josens, R

    2016-08-01

    Liquid sugar baits are well accepted by the Argentine ant Linepithema humile and are suitable for the chemical control of this invasive species. We evaluated how sugar concentrations affect the foraging behavior of L. humile individuals. We quantified feeding variables for individual foragers (ingested load, feeding time and solution intake rate) when feeding on sucrose solutions of different concentrations, as well as post-feeding interactions with nestmates. Solutions of intermediate sucrose concentrations (10-30%) were the most consumed and had the highest intake rates, whereas solutions of high sucrose concentrations (60 and 70%) resulted in extended feeding times, low intake rates and ants having smaller crop loads. In terms of post-feeding interactions, individuals fed solutions of intermediate sucrose concentrations (20%) had the highest probability of conducting trophallaxis and the smallest latency to drop exposure (i.e. lowest time delay). Trophallaxis duration increased with increasing sucrose concentrations. Behavioral motor displays, including contacts with head jerking and walking with a gaster waggle, were lowest for individuals that ingested the more dilute sucrose solution (5%). These behaviors have been previously suggested to act as a communication channel for the activation and/or recruitment of nestmates. We show here that sucrose concentration affects feeding dynamics and modulates decision making related to individual behavior and social interactions of foragers. Our results indicate that intermediate sucrose concentrations (ca. 20%), appear to be most appropriate for toxic baits because they promote rapid foraging cycles, a high crop load per individual, and a high degree of stimulation for recruitment. PMID:27063551

  1. Scheme of 3 interfaces with local isostatic compensation on the Argentine continental margin

    NASA Astrophysics Data System (ADS)

    Pedraza De Marchi, A. C.; Ghidella, M. E.; Tocho, C.

    2013-05-01

    The segment of Argentine continental margin located between 39°S and the Malvinas platform (~49°S) is of passive type and volcanic characteristics revealed by seaward-dipping seismic reflectors sequences (SDRs). The free air gravity edge-effect associated with passive continental margins is one of the most distinctive characteristics of gravity in marine regions. This effect is in large part due to the transition between continental and oceanic crusts, because of their different thicknesses. In this presentation we investigate the Airy type isostatic compensation scheme by using three interfaces in a forward calculation with different approximations of Parker's expression to obtain the isostatic anomaly. After that we perform the inversion of the anomaly thus obtained in order to find the Moho's deflection necessary to compensate it (or minimize it) by using the same scheme of interfaces and the iterative Parker-Oldenburg method (Oldenburg, D., 1974) with more terms in the inversion. The crust-mantle interface (Moho) thus calculated represents a more realistic surface than the one calculated using one term in the inversion and the surface estimated with topographic data and sediment thickness. Even considering that the experiment constitutes a schematic assumption just to test the numerical methods involved, we find that in the comparison with the only available digitized refraction profile, the inverted Moho interface reproduces fairly well the Moho that the seismic profile yields, for the case of the iterative method. This suggests that the inverse calculation with the iterative method is sensible to the presence of the SDRS, at least for this sole profile. Keywords: isostatic anomaly, Moho, passive continental margins Oldenburg, D., 1974. The inversion and interpretation of gravity anomalíes, Geophysics, vol. 39, no. 4, p. 526-536.

  2. Genotypes and clinical aspects associated with bone mineral density in Argentine postmenopausal women.

    PubMed

    Pérez, Adriana; Ulla, María; García, Beatriz; Lavezzo, María; Elías, Eliana; Binci, Miriam; Rivoira, María; Centeno, Viviana; Alisio, Arturo; Tolosa de Talamoni, Nori

    2008-01-01

    The aim of this study was to determine genotypes and clinical aspects associated with bone mineral density (BMD) in postmenopausal women from Córdoba, Argentina. Polymorphisms were assessed by RFLP-PCR technique using BsmI and FokI for vitamin D receptor gene (VDR) and XbaI and PvuII for estrogen receptor-alpha gene (ERalpha) as restrictases. Sixty-eight healthy, 54 osteopenic, and 64 osteoporotic postmenopausal women were recruited. Femoral neck and lumbar spine BMD were inversely correlated with age in the entire analyzed population. Height was lower in osteopenic and osteoporotic women as compared to healthy women (P < 0.05). Weight and body mass index (BMI) were the lowest in osteoporotic women (P < 0.01 versus healthy group). Serum procollagen type I Nterminal propeptide (PINP) was higher in osteoporotic women as compared to the other groups. Distribution of VDR and ERalpha genotypes was similar in the three groups. Genotype bb (VDR) was associated with low values of lumbar BMD in the healthy group (P < 0.05 versus genotype Bb), and with low values of femoral BMD (P < 0.05 versus genotype BB) in osteoporotic women. BB*Pp interaction was associated with the highest femoral neck BMD (P < 0.05), whereas the bb*xx interaction was associated with the lowest femoral neck BMD in the total population analyzed (P < 0.05). In conclusion, parameters such as age, height, weight, BMI, serum PINP, VDR genotypes, and interactions between VDR and ERalpha genotypes could be useful to predict a decrease in BMD in Argentine postmenopausal women. PMID:18600402

  3. Fine-scale genetic structure of Triatoma infestans in the Argentine Chaco.

    PubMed

    Piccinali, Romina Valeria; Gürtler, Ricardo Esteban

    2015-08-01

    The patterns of genetic structure in natural populations provide essential information for the improvement of pest management strategies including those targeting arthropod vectors of human diseases. We analyzed the patterns of fine-scale genetic structure in Triatoma infestans in a well-defined rural area close to Pampa del Indio, in the Argentine Arid-Humid Chaco transition, where a longitudinal study on house infestation and wing geometric morphometry is being conducted since 2007. A total of 228 insects collected in 16 domestic and peridomestic sites from two rural communities was genotyped for 10 microsatellite loci and analyzed. We did not find departures from Hardy-Weinberg expectations in collection sites, with three exceptions probably due to null alleles and substructuring. Domestic sites were more variable than peridomestic sites suggesting the presence of older bug populations in domestic sites or higher effective population sizes. Significant genetic structure was detected using F-statistics, a discriminant analysis of principal components and Bayesian clustering algorithms in an area of only 6.32 km(2). Microsatellite markers detected population structuring at a finer geographic scale (180-6300 m) than a previous study based on wing geometric morphometry (>4000 m). The spatial distribution of genetic variability was more properly explained by a hierarchical island than by an isolation-by-distance model. This study illustrates that, despite more than a decade without vector control interventions enhancing differentiation, genetic structure can be detected in T. infestans populations, particularly applying spatial information. This supports the potential of genetic studies to provide key information for hypothesis testing of the origins of house reinfestation. PMID:26027923

  4. Suspending the next turn as a form of repair initiation: evidence from Argentine Sign Language

    PubMed Central

    Manrique, Elizabeth; Enfield, N. J.

    2015-01-01

    Practices of other-initiated repair deal with problems of hearing or understanding what another person has said in the fast-moving turn-by-turn flow of conversation. As such, other-initiated repair plays a fundamental role in the maintenance of intersubjectivity in social interaction. This study finds and analyses a special type of other-initiated repair that is used in turn-by-turn conversation in a sign language: Argentine Sign Language (Lengua de Señas Argentina or LSA). We describe a type of response termed a “freeze-look,” which occurs when a person has just been asked a direct question: instead of answering the question in the next turn position, the person holds still while looking directly at the questioner. In these cases it is clear that the person is aware of having just been addressed and is not otherwise accounting for their delay in responding (e.g., by displaying a “thinking” face or hesitation, etc.). We find that this behavior functions as a way for an addressee to initiate repair by the person who asked the question. The “freeze-look” results in the questioner “re-doing” their action of asking a question, for example by repeating or rephrasing it. Thus, we argue that the “freeze-look” is a practice for other-initiation of repair. In addition, we argue that it is an “off-record” practice, thus contrasting with known on-record practices such as saying “Huh?” or equivalents. The findings aim to contribute to research on human understanding in everyday turn-by-turn conversation by looking at an understudied sign language, with possible implications for our understanding of visual bodily communication in spoken languages as well. PMID:26441710

  5. Adaptation to Interannual and Interdecadal Climate Variability in Agricultural Production Systems of the Argentine Pampas

    NASA Astrophysics Data System (ADS)

    Podestá, G. P.; Bert, F.; Weber, E.; Laciana, C.; Rajagopalan, B.; Letson, D.

    2007-05-01

    Agricultural ecosystems play a central role in world food production and food security, and involve one of the most climate-sensitive sectors of society-agriculture. We focus on crop production in the Argentine Pampas, one of the world's major agricultural regions. Climate of the Pampas shows marked variability at both interannual and decadal time scales. We explored the scope for adaptive management in response to climate information on interannual scales. We show that different assumptions about what decision makers are trying to achieve (i.e., their objective functions) may change what actions are considered as "optimal" for a given climate context. Optimal actions also were used to estimate the economic value of forecasts of an ENSO phase. Decision constraints (e.g., crop rotations) have critical influence on value of the forecasting system. Gaps in knowledge or misconceptions about climate variability were identified in open-ended "mental model" interviews. Results were used to design educational interventions. A marked increase in precipitation since the 1970s, together with new production technologies, led to major changes in land use patterns in the Pampas. Continuous cropping has widely replaced agriculture-pasture rotations. Nevertheless, production systems that evolved partly in response to increased rainfall may not be viable if climate reverts to a drier epoch. We use historical data to define a range of plausible climate trajectories 20-30 years hence. Regional scenarios are downscaled using semi-parametric weather generators to produce multiple realizations of daily weather consistent with decadal scenarios. Finally, we use the synthetic climate, crop growth models, and realistic models of decision-making under risk to compute risk metrics (e.g., probability of yields or profits being below a threshold). Climatically optimal and marginal locations show differential responses: probabilities of negative economic results are much higher in currently

  6. Ordovician K-bentonites in the Argentine Precordillera: relations to Gondwana margin evolution

    USGS Publications Warehouse

    Huff, W.D.; Bergstrom, Stig M.; Kolata, Dennis R.; Cingolani, C.A.; Astini, R.A.

    1998-01-01

    This paper is included in the Special Publication entitled 'The proto- Andean margin of Gondwana', edited by R.J. Pankhurst and C.W. Rapela. Ordovician K-bentonites have now been recorded from >20 localities in the vicinity of the Argentine Precordillera. Most occur in the eastern thrust belts, in the San Juan Limestone and the overlying the Gualcamayo Formation, but a few ash beds are known also from the central thrust belts. The oldest occur in the middle Arenig I, victoriae lunatus graptolite (Oe. evae conodont) Zone, and the youngest in the middle Llanvirn P. elegans (P. suecicus) Zone. Mineralogical characteristics, typical of other Ordovician K-bentonites, include a matrix of illite/smectite mixed-layer clay and a typical felsic volcanic phenocryst assemblage: biotite, beta-form quartz, alkali and plagioclase feldspar, apatite, and zircon, with lesser amounts of hornblende, clinopyroxene, titanite and Fe-Ti oxides. The proportions of the mineral phases and variations in their crystal chemistry are commonly unique to individual (or small groups of) K-bentonite beds. Glass melt inclusions preserved in quartz are rhyolitic in composition. The sequence is unique in its abundance of K-bentonite beds, but a close association between the Precordillera and other Ordovician sedimentary basins cannot be established. The ash distribution is most consistent with palaeogeographical reconstructions in which early Ordovician drifting of the Precordillera occurred in proximity to one or more volcanic arcs, and with eventual collision along the Andean margin of Gondwana during the mid-Ordovician Ocloyic event of the Famatinian orogeny. The Puna-Famatina terrane northeast of the Precordillera might have served as the source of the K-bentonite ashes, possibly in concert with active arc magmatism on the Gondwana plate itself.

  7. The Utility of Seasonal Climate Forecasts: Understanding Argentine Farmers' Attribute Priorities and Trade-Offs

    NASA Astrophysics Data System (ADS)

    Seipt, E. C.; Easterling, W. E.

    2007-05-01

    A distinct El Niño - Southern Oscillation (ENSO) signal and its impacts have been confirmed in the Argentine Pampas, and precipitation variability is currently recognized as the region's most marked ENSO-driven influence. In the Pampas, precipitation is also a major limiting factor for agricultural production given spatial differences in soil water storage capacities and the region's relatively minimal use of irrigation. Seasonal climate forecasts that provide advanced knowledge of expected ENSO-driven precipitation anomalies may benefit farm management decision-making by helping to either mitigate potentially negative consequences or to take advantage of potentially positive influences. To be useful and applicable, however, these forecasts must suit the decisions that they are meant to inform. In this research, a case study is presented that investigates how farmers in the Pampas prioritize and trade off specific attributes of a seasonal climate forecast (i.e., mode of distribution, spatial resolution, lead time, and forecast performance) when judging its utility. A conjoint analysis evaluation decomposes holistic evaluations of forecasts into the part-worth utilities associated with their different attributes. Part-worth utilities combine to reveal the structure of farmers' forecast utility preferences - a model of the decision-making process. Utility preference structures are analyzed to compute the importance value of each attribute and to determine the trade-offs that farmers find acceptable between different attributes. Analysis indicates that, on average, spatial resolution is the most influential attribute in determining climate forecast utility. Attribute trade-off values suggest that advances in spatial resolution, forecast performance, and/or product dissemination via the Internet offer the greatest potential for increasing the utility of future seasonal climate forecasts for farmers in the Pampas.

  8. Suspending the next turn as a form of repair initiation: evidence from Argentine Sign Language.

    PubMed

    Manrique, Elizabeth; Enfield, N J

    2015-01-01

    Practices of other-initiated repair deal with problems of hearing or understanding what another person has said in the fast-moving turn-by-turn flow of conversation. As such, other-initiated repair plays a fundamental role in the maintenance of intersubjectivity in social interaction. This study finds and analyses a special type of other-initiated repair that is used in turn-by-turn conversation in a sign language: Argentine Sign Language (Lengua de Señas Argentina or LSA). We describe a type of response termed a "freeze-look," which occurs when a person has just been asked a direct question: instead of answering the question in the next turn position, the person holds still while looking directly at the questioner. In these cases it is clear that the person is aware of having just been addressed and is not otherwise accounting for their delay in responding (e.g., by displaying a "thinking" face or hesitation, etc.). We find that this behavior functions as a way for an addressee to initiate repair by the person who asked the question. The "freeze-look" results in the questioner "re-doing" their action of asking a question, for example by repeating or rephrasing it. Thus, we argue that the "freeze-look" is a practice for other-initiation of repair. In addition, we argue that it is an "off-record" practice, thus contrasting with known on-record practices such as saying "Huh?" or equivalents. The findings aim to contribute to research on human understanding in everyday turn-by-turn conversation by looking at an understudied sign language, with possible implications for our understanding of visual bodily communication in spoken languages as well. PMID:26441710

  9. BOILING REACTORS

    DOEpatents

    Untermyer, S.

    1962-04-10

    A boiling reactor having a reactivity which is reduced by an increase in the volume of vaporized coolant therein is described. In this system unvaporized liquid coolant is extracted from the reactor, heat is extracted therefrom, and it is returned to the reactor as sub-cooled liquid coolant. This reduces a portion of the coolant which includes vaporized coolant within the core assembly thereby enhancing the power output of the assembly and rendering the reactor substantially self-regulating. (AEC)

  10. NEUTRONIC REACTOR

    DOEpatents

    Daniels, F.

    1959-10-27

    A reactor in which at least a portion of the moderator is in the form of movable refractory balls is described. In addition to their moderating capacity, these balls may serve as carriers for fissionable material or fertile material, or may serve in a coolant capacity to remove heat from the reactor. A pneumatic system is used to circulate the balls through the reactor.

  11. CONVECTION REACTOR

    DOEpatents

    Hammond, R.P.; King, L.D.P.

    1960-03-22

    An homogeneous nuclear power reactor utilizing convection circulation of the liquid fuel is proposed. The reactor has an internal heat exchanger looated in the same pressure vessel as the critical assembly, thereby eliminating necessity for handling the hot liquid fuel outside the reactor pressure vessel during normal operation. The liquid fuel used in this reactor eliminates the necessity for extensive radiolytic gas rocombination apparatus, and the reactor is resiliently pressurized and, without any movable mechanical apparatus, automatically regulates itself to the condition of criticality during moderate variations in temperature snd pressure and shuts itself down as the pressure exceeds a predetermined safe operating value.

  12. Research reactors

    SciTech Connect

    Tonneson, L.C.; Fox, G.J.

    1996-04-01

    There are currently 284 research reactors in operation, and 12 under construction around the world. Of the operating reactors, nearly two-thirds are used exclusively for research, and the rest for a variety of purposes, including training, testing, and critical assembly. For more than 50 years, research reactor programs have contributed greatly to the scientific and educational communities. Today, six of the world`s research reactors are being shut down, three of which are in the USA. With government budget constraints and the growing proliferation concerns surrounding the use of highly enriched uranium in some of these reactors, the future of nuclear research could be impacted.

  13. Eddy-driven sediment transport in the Argentine Basin: Is the height of the Zapiola Rise hydrodynamically controlled?

    SciTech Connect

    Weijer, Wilbert; Maltrud, Mathew E.; Homoky, William B.; Polzin, Kurt L.; Maas, Leo R. M.

    2015-03-27

    In this study, we address the question whether eddy-driven transports in the Argentine Basin can be held responsible for enhanced sediment accumulation over the Zapiola Rise, hence accounting for the existence and growth of this sediment drift. To address this question, we perform a 6 year simulation with a strongly eddying ocean model. We release two passive tracers, with settling velocities that are consistent with silt and clay size particles. Our experiments show contrasting behavior between the silt fraction and the lighter clay. Due to its larger settling velocity, the silt fraction reaches a quasisteady state within a few years, with abyssal sedimentation rates that match net input. In contrast, clay settles only slowly, and its distribution is heavily stratified, being transported mainly along isopycnals. Yet, both size classes display a significant and persistent concentration minimum over the Zapiola Rise. We show that the Zapiola Anticyclone, a strong eddy-driven vortex that circulates around the Zapiola Rise, is a barrier to sediment transport, and hence prevents significant accumulation of sediments on the Rise. We conclude that sediment transport by the turbulent circulation in the Argentine Basin alone cannot account for the preferred sediment accumulation over the Rise. We speculate that resuspension is a critical process in the formation and maintenance of the Zapiola Rise.

  14. Eddy-driven sediment transport in the Argentine Basin: Is the height of the Zapiola Rise hydrodynamically controlled?

    DOE PAGESBeta

    Weijer, Wilbert; Maltrud, Mathew E.; Homoky, William B.; Polzin, Kurt L.; Maas, Leo R. M.

    2015-03-27

    In this study, we address the question whether eddy-driven transports in the Argentine Basin can be held responsible for enhanced sediment accumulation over the Zapiola Rise, hence accounting for the existence and growth of this sediment drift. To address this question, we perform a 6 year simulation with a strongly eddying ocean model. We release two passive tracers, with settling velocities that are consistent with silt and clay size particles. Our experiments show contrasting behavior between the silt fraction and the lighter clay. Due to its larger settling velocity, the silt fraction reaches a quasisteady state within a few years,more » with abyssal sedimentation rates that match net input. In contrast, clay settles only slowly, and its distribution is heavily stratified, being transported mainly along isopycnals. Yet, both size classes display a significant and persistent concentration minimum over the Zapiola Rise. We show that the Zapiola Anticyclone, a strong eddy-driven vortex that circulates around the Zapiola Rise, is a barrier to sediment transport, and hence prevents significant accumulation of sediments on the Rise. We conclude that sediment transport by the turbulent circulation in the Argentine Basin alone cannot account for the preferred sediment accumulation over the Rise. We speculate that resuspension is a critical process in the formation and maintenance of the Zapiola Rise.« less

  15. A paleomagnetic and relative paleointensity record from the Argentine Basin (western South Atlantic Ocean) for the last ~125 kyrs

    NASA Astrophysics Data System (ADS)

    Heil, C. W., Jr.; Stoner, J. S.; St-Onge, G.; King, J. W.

    2015-12-01

    The paucity of paleomagnetic records from the western South Atlantic Ocean presents a significant gap in our understanding of the spatial variations in geomagnetic field dynamics as they relate to the occurrence of geomagnetic excursions and changes in field strength. As such, high quality records from this region can help build upon Holocene observations and extend the geographic and temporal data coverage for spherical harmonic models. To that end, we present paleomagnetic directional (inclination) and strength (relative paleointensity) records from two cores from the Argentine Basin (RC11-49 and RC16-88). Although the cores were collected more than 40 years ago, the sediments appear to hold a stable remanence and reliable magnetic directions, as evidenced by their reproducibility between the two cores that are separated by ~25 km. The records show evidence of 4 excursional features in the uppermost 16-m of the sediments from the basin. A comparison of the relative paleointensity records from these cores to the South Atlantic Paleointensity Stack (SAPIS) (Stoner et al., 2002) and the relative paleointensity record from ODP Site 1089 (Stoner et al., 2003) indicate that the sediments reliably record relative changes in geomagnetic field intensity and suggests that the longest record (RC11-49) spans the last ~125 kyrs. Our results indicate that the sediments of the Argentine Basin are an important sedimentary archive of geomagnetic field behavior and strength at least through the Holocene and Late Pleistocene and highlight the need for further studies of cores within the basin.

  16. Determining the foraging range and origin of resurgence after treatment of Argentine ant (Hymenoptera: Formicidae) in urban areas.

    PubMed

    Vega, S Y; Rust, M K

    2003-06-01

    The foraging range and distribution of Argentine ant, Linepithema humile (Mayr), colonies in urban areas of southern California extended at least 61 m (200 feet) from feeding stations and structures. Ants were fed at 25% sucrose feeding stations containing 0.01% fluorescent brighter (FB28). Within 14 d, from 77-90% of the ants sampled next to the feeding stations were positive for FB28. The percentage of ants with FB28 declined gradually to approximately 55% 61 m away from the feeding station. The percentage of marked ants in the controls didn't change over the 4-wk-test period. There were approximately 290,000 ants visiting the monitored stations each night before treatments. The 0.0001% fipronil baits and 0.06% fipronil SC sprays provided significant reductions in at least 4 wk. The percentage of ants marked with FB28 decreased significantly in both bait and spray treatments over 4 wk suggesting that the resurgence of ants in treated areas were because of immigration from untreated areas. It is likely that much larger areas will need to be treated to control Argentine ants in urban settings, especially if baits are being used. PMID:12852625

  17. Hydroacoustical evidence of the expansion of pelagic swarms of Munida gregaria (Decapoda, Munididae) in the Beagle Channel and the Argentine Patagonian Shelf, and its relationship with habitat features

    NASA Astrophysics Data System (ADS)

    Diez, Mariano J.; Cabreira, Ariel G.; Madirolas, Adrián; Lovrich, Gustavo A.

    2016-08-01

    Squat lobsters are highly diversified and widespread decapods, of which only three species form pelagic swarms. Here we infer the expansion of Munida gregaria populations in the Beagle Channel and the Argentine Patagonian Shelf by means of acoustic surveys of pelagic swarms. We also describe the habitat characteristics in which these swarms occur. Acoustic data was collected during three multidisciplinary scientific cruises on board of the R/V Puerto Deseado during 2009, 2012 and 2014. Despite differences in the environmental conditions between the two surveyed areas, between 2009 and 2014 pelagic swarms increased their occurrence and abundance both in the Beagle Channel and on the Argentine Patagonian Shelf. Towards the end of the studied period, pelagic swarms of M. gregaria occurred in new locations, supporting the notion of a population expansion. Within the Beagle Channel swarm expansions were more marked than on the Patagonian Shelf. We here postulate that M. gregaria expansions occur in association with productive areas of the Argentine continental shelf, such as frontal zones, favoured by the squat lobster phenotypic plasticity that permit to exploit resources in both the neritic and benthic environments. At a regional scale on the Patagonian Shelf, three main groups of pelagic swarms of M. gregaria were clearly associated to respective frontal zones. The information presented here is necessary to understand fluctuations in both distribution and abundance patterns of a key species on the Argentine continental shelf. These fluctuations could be direct or indirect indicators of changes in the ecosystem.

  18. NEUTRONIC REACTOR

    DOEpatents

    Fraas, A.P.; Mills, C.B.

    1961-11-21

    A neutronic reactor in which neutron moderation is achieved primarily in its reflector is described. The reactor structure consists of a cylindrical central "island" of moderator and a spherical moderating reflector spaced therefrom, thereby providing an annular space. An essentially unmoderated liquid fuel is continuously passed through the annular space and undergoes fission while contained therein. The reactor, because of its small size, is particularly adapted for propulsion uses, including the propulsion of aircraft. (AEC)

  19. REACTOR COOLING

    DOEpatents

    Quackenbush, C.F.

    1959-09-29

    A nuclear reactor with provisions for selectively cooling the fuel elements is described. The reactor has a plurality of tubes extending throughout. Cylindrical fuel elements are disposed within the tubes and the coolant flows through the tubes and around the fuel elements. The fuel elements within the central portion of the reactor are provided with roughened surfaces of material. The fuel elements in the end portions of the tubes within the reactor are provlded with low conduction jackets and the fuel elements in the region between the central portion and the end portions are provided with smooth surfaces of high heat conduction material.

  20. Collaborative Physical and Biological Dosimetry Studies for Neutron Capture Therapy at the RA-1 Research Reactor Facility

    SciTech Connect

    David W. Nigg; Amanda E. Schwint; John K. Hartwell; Elisa M. Heber; Veronica Trivillin; Jorge Castillo; Luis Wentzeis; Patrick Sloan; Charles A. Wemple

    2004-10-01

    Initial physical dosimetry measurements have been completed using activation spectrometry and thermoluminiscent dosimeters to characterize the BNCT irradiation facility developed at the RA-1 research reactor operated by the Argentine National Atomic Energy Commission in Buenos Aires. Some biological scoping irradiations have also been completed using a small-animal (hamster) oral mucosa tumor model. Results indicate that the RA-1 neutron source produces useful dose rates but that some improvements in the initial configuration will be needed to optimize the spectrum for thermal-neutron BNCT research applications.

  1. Collaborative Physical and Biological Dosimetry Studies for Neutron Capture Therapy at the RA-1 Research Reactor Facility

    SciTech Connect

    Nigg, D.W.; Schwint, A.E.; Hartwell, J.K.; Heber, E.M.; Trivillin, V.; Castillo, J.; Wentzeis, L.; Sloan, P.; Wemple, C.A.

    2004-10-04

    Initial physical dosimetry measurements have been completed using activation spectrometry and thermoluminiscent dosimeters to characterize the BNCT irradiation facility developed at the RA-1 research reactor operated by the Argentine National Atomic Energy Commission in Buenos Aires. Some biological scoping irradiations have also been completed using a small-animal (hamster) oral mucosa tumor model. Results indicate that the RA-1 neutron source produces useful dose rates but that some improvements in the initial configuration will be needed to optimize the spectrum for thermal-neutron BNCT research applications.

  2. NEUTRONIC REACTOR

    DOEpatents

    Metcalf, H.E.; Johnson, H.W.

    1961-04-01

    BS>A nuclear reactor incorporating fuel rods passing through a moderator and including tubes of a material of higher Thermal conductivity than the fuel in contact with the fuel is described. The tubes extend beyond the active portion of the reactor into contant with a fiuld coolant.

  3. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.

    1958-04-22

    A nuclear reactor for isotope production is described. This reactor is designed to provide a maximum thermal neutron flux in a region adjacent to the periphery of the reactor rather than in the center of the reactor. The core of the reactor is generally centrally located with respect tn a surrounding first reflector, constructed of beryllium. The beryllium reflector is surrounded by a second reflector, constructed of graphite, which, in tune, is surrounded by a conventional thermal shield. Water is circulated through the core and the reflector and functions both as a moderator and a coolant. In order to produce a greatsr maximum thermal neutron flux adjacent to the periphery of the reactor rather than in the core, the reactor is designed so tbat the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the materials in the reflector is approximately twice the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the material of the core of the reactor.

  4. Dubinectes infirmus, a new species of deep-water Munnopsidae (Crustacea, Isopoda, Asellota) from the Argentine Basin, South Atlantic Ocean

    PubMed Central

    Malyutina, Marina; Brandt, Angelika

    2011-01-01

    Abstract Dubinectes infirmus sp. n., Munnopsidae, is described from the Argentine Basin, southwest Atlantic, at depths between 4586–4607 m. The new species is distinguished by a narrow rim of the pleotelson posterior margin which is not raising over its dorsal surface; article 3 of the antennula is subequal in length to article 2; distomedial lobes of male pleopod 1 are of same size as distolateral lobes; stylet of male pleopod 2 is subequal in length to protopod; uropod exopod is more than a half of endopod length. Some generic characters which are weakly pronounced in the new species or have different state are defined more precisely in the revised diagnosis of Dubinectes. The modified diagnosis of the genus, a key to the species of Dubinectes as well as the distribution of the genus are presented. PMID:22207784

  5. Dysphagia, melanosis, gastrointestinal stromal tumors and a germinal mutation of the KIT gene in an Argentine family.

    PubMed

    Adela Avila, Silvia; Peñaloza, José; González, Flavia; Abdo, Ivana; Rainville, Irene; Root, Elizabeth; Carrero Valenzuela, Roque Daniel; Garber, Judy

    2014-03-01

    Gastrointestinal stromal tumors (GIST) are the most common mesenchymatous neoplasms of the human digestive tract. They locate preferentially in stomach, duodenum or small bowel. Usually sporadic, familial cases unrelated to neurofibromatosis may be due to germline mutations in KIT or PDGFRA. We describe the first Argentine family with GIST in which we found, diffuse cutaneous melanosis, lentiginosis, and dysphagia. Dysphagia was not observed in the four families previously described with the same mutation. Histopathology resulted consistent with GIST, and tumor immunohistochemistry was likewise positive for DOG-1, CD117 (KIT) and CD34. The search for germline mutations identified the KIT c.1697T > C (p.559V > A) substitution in exon 11. Treatment with imatinib is furnishing positive results. PMID:24847623

  6. Exhuming retroarc fold-and-thrust belts: a comparison between the southern Patagonian Andes and the Argentine Precordillera

    NASA Astrophysics Data System (ADS)

    Fosdick, J. C.

    2014-12-01

    Detailed constraints on erosional flux are critical for understanding how exhumational processes control and respond to tectonic events in orogenic belts. This work compares the thermochronologic record and erosional behavior of retroarc thrust belts at two latitudes in the Andes with contrasting Cenozoic climate and deformational records: the glaciated southern Patagonian Andes and the semiarid Argentine Precordillera of the Central Andes. Both regions have undergone crustal shortening during Andean growth and have been affected by thermotectonic processes associated with subduction of oceanic ridges; the Chile Ridge spreading center and Juan Fernández Ridge, respectively. In Patagonia, deep erosion occurred during Miocene retroarc deformation. Zircon He thermochronology documents regional cooling and unroofing of the thrust belt ~22-17 Ma. This behavior likely reflects an upper plate manifestation of incipient subduction of the Chile Ridge spreading center and enhanced unroofing during thermally driven regional uplift. Late Cenozoic expansion of the Patagonian icesheet led to further excavation of the thrust belt, indicating a strong climatic overprinting on thrust belt erosional behavior. In contrast, less overall Cenozoic exhumation is observed in the Argentine Precordillera, despite high strain and crustal thickening. Pre-Jurassic zircon He dates from the Paleozoic strata within thrust sheets suggest Cenozoic Andean deformation was insufficient to exhume rocks from beneath the zircon He closure depth. The apatite He record shows a close correlation between thrust faulting and locus of erosion, and document eastward in-sequence rock cooling from 16 to 2 Ma across the Precordillera tracking with the progressive faulting of the Blanca, San Roque, and Niquivil thrust faults during this time. Pliocene apatite He dates located along the external margins of the Precordillera suggest that the most recent cooling and unroofing is associated with both out

  7. Structure, composition and metagenomic profile of soil microbiomes associated to agricultural land use and tillage systems in Argentine Pampas.

    PubMed

    Carbonetto, Belén; Rascovan, Nicolás; Álvarez, Roberto; Mentaberry, Alejandro; Vázquez, Martin P

    2014-01-01

    Agriculture is facing a major challenge nowadays: to increase crop production for food and energy while preserving ecosystem functioning and soil quality. Argentine Pampas is one of the main world producers of crops and one of the main adopters of conservation agriculture. Changes in soil chemical and physical properties of Pampas soils due to different tillage systems have been deeply studied. Still, not much evidence has been reported on the effects of agricultural practices on Pampas soil microbiomes. The aim of our study was to investigate the effects of agricultural land use on community structure, composition and metabolic profiles on soil microbiomes of Argentine Pampas. We also compared the effects associated to conventional practices with the effects of no-tillage systems. Our results confirmed the impact on microbiome structure and composition due to agricultural practices. The phyla Verrucomicrobia, Plactomycetes, Actinobacteria, and Chloroflexi were more abundant in non cultivated soils while Gemmatimonadetes, Nitrospirae and WS3 were more abundant in cultivated soils. Effects on metabolic metagenomic profiles were also observed. The relative abundance of genes assigned to transcription, protein modification, nucleotide transport and metabolism, wall and membrane biogenesis and intracellular trafficking and secretion were higher in cultivated fertilized soils than in non cultivated soils. We also observed significant differences in microbiome structure and taxonomic composition between soils under conventional and no-tillage systems. Overall, our results suggest that agronomical land use and the type of tillage system have induced microbiomes to shift their life-history strategies. Microbiomes of cultivated fertilized soils (i.e. higher nutrient amendment) presented tendencies to copiotrophy while microbiomes of non cultivated homogenous soils appeared to have a more oligotrophic life-style. Additionally, we propose that conventional tillage systems may

  8. Structure, Composition and Metagenomic Profile of Soil Microbiomes Associated to Agricultural Land Use and Tillage Systems in Argentine Pampas

    PubMed Central

    Carbonetto, Belén; Rascovan, Nicolás; Álvarez, Roberto; Mentaberry, Alejandro; Vázquez, Martin P.

    2014-01-01

    Agriculture is facing a major challenge nowadays: to increase crop production for food and energy while preserving ecosystem functioning and soil quality. Argentine Pampas is one of the main world producers of crops and one of the main adopters of conservation agriculture. Changes in soil chemical and physical properties of Pampas soils due to different tillage systems have been deeply studied. Still, not much evidence has been reported on the effects of agricultural practices on Pampas soil microbiomes. The aim of our study was to investigate the effects of agricultural land use on community structure, composition and metabolic profiles on soil microbiomes of Argentine Pampas. We also compared the effects associated to conventional practices with the effects of no-tillage systems. Our results confirmed the impact on microbiome structure and composition due to agricultural practices. The phyla Verrucomicrobia, Plactomycetes, Actinobacteria, and Chloroflexi were more abundant in non cultivated soils while Gemmatimonadetes, Nitrospirae and WS3 were more abundant in cultivated soils. Effects on metabolic metagenomic profiles were also observed. The relative abundance of genes assigned to transcription, protein modification, nucleotide transport and metabolism, wall and membrane biogenesis and intracellular trafficking and secretion were higher in cultivated fertilized soils than in non cultivated soils. We also observed significant differences in microbiome structure and taxonomic composition between soils under conventional and no- tillage systems. Overall, our results suggest that agronomical land use and the type of tillage system have induced microbiomes to shift their life-history strategies. Microbiomes of cultivated fertilized soils (i.e. higher nutrient amendment) presented tendencies to copiotrophy while microbiomes of non cultivated homogenous soils appeared to have a more oligotrophic life-style. Additionally, we propose that conventional tillage systems

  9. Compact Reactor

    SciTech Connect

    Williams, Pharis E.

    2007-01-30

    Weyl's Gauge Principle of 1929 has been used to establish Weyl's Quantum Principle (WQP) that requires that the Weyl scale factor should be unity. It has been shown that the WQP requires the following: quantum mechanics must be used to determine system states; the electrostatic potential must be non-singular and quantified; interactions between particles with different electric charges (i.e. electron and proton) do not obey Newton's Third Law at sub-nuclear separations, and nuclear particles may be much different than expected using the standard model. The above WQP requirements lead to a potential fusion reactor wherein deuterium nuclei are preferentially fused into helium nuclei. Because the deuterium nuclei are preferentially fused into helium nuclei at temperatures and energies lower than specified by the standard model there is no harmful radiation as a byproduct of this fusion process. Therefore, a reactor using this reaction does not need any shielding to contain such radiation. The energy released from each reaction and the absence of shielding makes the deuterium-plus-deuterium-to-helium (DDH) reactor very compact when compared to other reactors, both fission and fusion types. Moreover, the potential energy output per reactor weight and the absence of harmful radiation makes the DDH reactor an ideal candidate for space power. The logic is summarized by which the WQP requires the above conditions that make the prediction of DDH possible. The details of the DDH reaction will be presented along with the specifics of why the DDH reactor may be made to cause two deuterium nuclei to preferentially fuse to a helium nucleus. The presentation will also indicate the calculations needed to predict the reactor temperature as a function of fuel loading, reactor size, and desired output and will include the progress achieved to date.

  10. NUCLEAR REACTOR

    DOEpatents

    Moore, R.V.; Bowen, J.H.; Dent, K.H.

    1958-12-01

    A heterogeneous, natural uranium fueled, solid moderated, gas cooled reactor is described, in which the fuel elements are in the form of elongated rods and are dlsposed within vertical coolant channels ln the moderator symmetrically arranged as a regular lattice in groups. This reactor employs control rods which operate in vertical channels in the moderator so that each control rod is centered in one of the fuel element groups. The reactor is enclosed in a pressure vessel which ls provided with access holes at the top to facilitate loading and unloadlng of the fuel elements, control rods and control rod driving devices.

  11. NUCLEAR REACTOR

    DOEpatents

    Sherman, J.; Sharbaugh, J.E.; Fauth, W.L. Jr.; Palladino, N.J.; DeHuff, P.G.

    1962-10-23

    A nuclear reactor incorporating seed and blanket assemblies is designed. Means are provided for obtaining samples of the coolant from the blanket assemblies and for varying the flow of coolant through the blanket assemblies. (AEC)

  12. NEUTRONIC REACTOR

    DOEpatents

    Anderson, H.L.

    1960-09-20

    A nuclear reactor is described comprising fissionable material dispersed in graphite blocks, helium filling the voids of the blocks and the spaces therebetween, and means other than the helium in thermal conductive contact with the graphite for removing heat.

  13. NEUTRONIC REACTOR

    DOEpatents

    Hurwitz, H. Jr.; Brooks, H.; Mannal, C.; Payne, J.H.; Luebke, E.A.

    1959-03-24

    A reactor of the heterogeneous, liquid cooled type is described. This reactor is comprised of a central region of a plurality of vertically disposed elongated tubes surrounded by a region of moderator material. The central region is comprised of a central core surrounded by a reflector region which is surrounded by a fast neutron absorber region, which in turn is surrounded by a slow neutron absorber region. Liquid sodium is used as the primary coolant and circulates through the core which contains the fuel elements. Control of the reactor is accomplished by varying the ability of the reflector region to reflect neutrons back into the core of the reactor. For this purpose the reflector is comprised of moderator and control elements having varying effects on reactivity, the control elements being arranged and actuated by groups to give regulation, shim, and safety control.

  14. NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.

    1960-04-01

    A nuclear reactor is described consisting of blocks of graphite arranged in layers, natural uranium bodies disposed in holes in alternate layers of graphite blocks, and coolant tubes disposed in the layers of graphite blocks which do not contain uranium.

  15. REACTOR SHIELD

    DOEpatents

    Wigner, E.P.; Ohlinger, L.E.; Young, G.J.; Weinberg, A.M.

    1959-02-17

    Radiation shield construction is described for a nuclear reactor. The shield is comprised of a plurality of steel plates arranged in parallel spaced relationship within a peripheral shell. Reactor coolant inlet tubes extend at right angles through the plates and baffles are arranged between the plates at right angles thereto and extend between the tubes to create a series of zigzag channels between the plates for the circulation of coolant fluid through the shield. The shield may be divided into two main sections; an inner section adjacent the reactor container and an outer section spaced therefrom. Coolant through the first section may be circulated at a faster rate than coolant circulated through the outer section since the area closest to the reactor container is at a higher temperature and is more radioactive. The two sections may have separate cooling systems to prevent the coolant in the outer section from mixing with the more contaminated coolant in the inner section.

  16. NUCLEAR REACTOR

    DOEpatents

    Miller, H.I.; Smith, R.C.

    1958-01-21

    This patent relates to nuclear reactors of the type which use a liquid fuel, such as a solution of uranyl sulfate in ordinary water which acts as the moderator. The reactor is comprised of a spherical vessel having a diameter of about 12 inches substantially surrounded by a reflector of beryllium oxide. Conventionnl control rods and safety rods are operated in slots in the reflector outside the vessel to control the operation of the reactor. An additional means for increasing the safety factor of the reactor by raising the ratio of delayed neutrons to prompt neutrons, is provided and consists of a soluble sulfate salt of beryllium dissolved in the liquid fuel in the proper proportion to obtain the result desired.

  17. NUCLEAR REACTOR

    DOEpatents

    Anderson, C.R.

    1962-07-24

    A fluidized bed nuclear reactor and a method of operating such a reactor are described. In the design means are provided for flowing a liquid moderator upwardly through the center of a bed of pellets of a nentron-fissionable material at such a rate as to obtain particulate fluidization while constraining the lower pontion of the bed into a conical shape. A smooth circulation of particles rising in the center and falling at the outside of the bed is thereby established. (AEC)

  18. NUCLEAR REACTOR

    DOEpatents

    Breden, C.R.; Dietrich, J.R.

    1961-06-20

    A water-soluble non-volatile poison may be introduced into a reactor to nullify excess reactivity. The poison is removed by passing a side stream of the water containing the soluble poison to an evaporation chamber. The vapor phase is returned to the reactor to decrease the concentration of soluble poison and the liquid phase is returned to increase the concentration of soluble poison.

  19. NUCLEAR REACTOR

    DOEpatents

    Grebe, J.J.

    1959-07-14

    High temperature reactors which are uniquely adapted to serve as the heat source for nuclear pcwered rockets are described. The reactor is comprised essentially of an outer tubular heat resistant casing which provides the main coolant passageway to and away from the reactor core within the casing and in which the working fluid is preferably hydrogen or helium gas which is permitted to vaporize from a liquid storage tank. The reactor core has a generally spherical shape formed entirely of an active material comprised of fissile material and a moderator material which serves as a diluent. The active material is fabricated as a gas permeable porous material and is interlaced in a random manner with very small inter-connecting bores or capillary tubes through which the coolant gas may flow. The entire reactor is divided into successive sections along the direction of the temperature gradient or coolant flow, each section utilizing materials of construction which are most advantageous from a nuclear standpoint and which at the same time can withstand the operating temperature of that particular zone. This design results in a nuclear reactor characterized simultaneously by a minimum critiral size and mass and by the ability to heat a working fluid to an extremely high temperature.

  20. Integrating physiology, population dynamics and climate to make multi-scale predictions for the spread of an invasive insect: the Argentine ant at Haleakala National Park, Hawaii

    USGS Publications Warehouse

    Hartley, Stephen; Krushelnycky, Paul D.; Lester, Philip J.

    2010-01-01

    Mechanistic models for predicting species’ distribution patterns present particular advantages and challenges relative to models developed from statistical correlations between distribution and climate. They can be especially useful for predicting the range of invasive species whose distribution has not yet reached equilibrium. Here, we illustrate how a physiological model of development for the invasive Argentine ant can be connected to differences in micro-site suitability, population dynamics and climatic gradients; processes operating at quite different spatial scales. Our study is located in the subalpine shrubland of Haleakala National Park, Hawaii, where the spread of Argentine ants Linepithema humile has been documented for the past twenty-five years. We report four main results. First, at a microsite level, the accumulation of degree-days recorded in potential ant nest sites under bare ground or rocks was significantly greater than under a groundcover of grassy vegetation. Second, annual degree-days measured where population boundaries have not expanded (456-521 degree-days), were just above the developmental requirements identified from earlier laboratory studies (445 degree-days above 15.98C). Third, rates of population expansion showed a strong linear relationship with annual degree-days. Finally, an empirical relationship between soil degree-days and climate variables mapped at a broader scale predicts the potential for future range expansion of Argentine ants at Haleakala, particularly to the west of the lower colony and the east of the upper colony. Variation in the availability of suitable microsites, driven by changes in vegetation cover and ultimately climate, provide a hierarchical understanding of the distribution of Argentine ants close to their cold-wet limit of climatic tolerances. We conclude that the integration of physiology, population dynamics and climate mapping holds much promise for making more robust predictions about

  1. Research reactors - an overview

    SciTech Connect

    West, C.D.

    1997-03-01

    A broad overview of different types of research and type reactors is provided in this paper. Reactor designs and operating conditions are briefly described for four reactors. The reactor types described include swimming pool reactors, the High Flux Isotope Reactor, the Mark I TRIGA reactor, and the Advanced Neutron Source reactor. Emphasis in the descriptions is placed on safety-related features of the reactors. 7 refs., 7 figs., 2 tabs.

  2. NEUTRONIC REACTOR

    DOEpatents

    Ohlinger, L.A.; Wigner, E.P.; Weinberg, A.M.; Young, G.J.

    1958-09-01

    This patent relates to neutronic reactors of the heterogeneous water cooled type, and in particular to a fuel element charging and discharging means therefor. In the embodiment illustrated the reactor contains horizontal, parallel coolant tubes in which the fuel elements are disposed. A loading cart containing a magnzine for holding a plurality of fuel elements operates along the face of the reactor at the inlet ends of the coolant tubes. The loading cart is equipped with a ram device for feeding fuel elements from the magazine through the inlot ends of the coolant tubes. Operating along the face adjacent the discharge ends of the tubes there is provided another cart means adapted to receive irradiated fuel elements as they are forced out of the discharge ends of the coolant tubes by the incoming new fuel elements. This cart is equipped with a tank coataining a coolant, such as water, into which the fuel elements fall, and a hydraulically operated plunger to hold the end of the fuel element being discharged. This inveation provides an apparatus whereby the fuel elements may be loaded into the reactor, irradiated therein, and unloaded from the reactor without stopping the fiow of the coolant and without danger to the operating personnel.

  3. Comparative study of spawning pattern and reproductive potential of the Northern and Southern stocks of Argentine hake (Merluccius hubbsi)

    NASA Astrophysics Data System (ADS)

    Rodrigues, Karina A.; Macchi, Gustavo J.; Militelli, Maria I.

    2015-08-01

    The reproductive biology of the Northern (Bonaerense) and Southern (Patagonian) stocks of Merluccius hubbsi in the Argentinean Sea is analyzed, including information on spawning areas, estimates of abundance and size composition of spawning females, fecundity, spawning frequency and egg quality. Samples of Argentine hake were obtained during the period of peak reproductive activity; May and January for the Northern and Southern stocks, respectively. The size of the reproductive area for the Northern stock (35-38°S) was clearly smaller than the one estimated for the Southern population (43°30‧-46°S), being 23,770 km2 and 52,460 km2 respectively. Spawning females from the Northern reproductive area were smaller (modal values between 35 and 40 cm TL) than those from the Southern stock (modal values between 38 and 50 cm TL), and they were also less abundant in number and had a lower spawning frequency (8-13 days and 5-7 days between partial spawning for the Northern and Southern stocks respectively). No differences in batch and relative fecundity between stocks were recorded (mean values of 526 and 530 hydrated oocytes g- 1), but the dry weights of hydrated oocytes from females of the Northern group were higher (3.08 mg for 100 hydrated oocytes) than those of the Patagonian stock (2.84 mg) for the same total length range. The egg production during the month of peak spawning of the Northern group depended mostly on the smaller females (< 50 cm TL) and was in average 1 to 2 orders of magnitude lower than that estimated for the Southern stock (9 × 1012-22 × 1012 eggs and 692 × 1012-1295 × 1012 eggs for the Northern and Southern stocks respectively). Those differences in egg production and the high productivity and retentive characteristics described for the spawning area and nursery ground in Patagonian waters would justify the greater abundance and resilience of the Southern stock of Argentine hake. The low abundance of females in spawning capable stage observed

  4. POWER REACTOR

    DOEpatents

    Zinn, W.H.

    1958-07-01

    A fast nuclear reactor system ls described for producing power and radioactive isotopes. The reactor core is of the heterogeneous, fluid sealed type comprised of vertically arranged elongated tubular fuel elements having vertical coolant passages. The active portion is surrounded by a neutron reflector and a shield. The system includes pumps and heat exchangers for the primary and secondary coolant circuits. The core, primary coolant pump and primary heat exchanger are disposed within an irapenforate tank which is filled with the primary coolant, in this case a liquid metal such as Na or NaK, to completely submerge these elements. The tank is completely surrounded by a thick walled concrete shield. This reactor system utilizes enriched uranium or plutonium as the fissionable material, uranium or thorium as a diluent and thorium or uranium containing less than 0 7% of the U/sup 235/ isotope as a fertile material.

  5. NEUTRONIC REACTORS

    DOEpatents

    Wigner, E.P.; Young, G.J.

    1958-10-14

    A method is presented for loading and unloading rod type fuel elements of a neutronic reactor of the heterogeneous, solld moderator, liquid cooled type. In the embodiment illustrated, the fuel rods are disposed in vertical coolant channels in the reactor core. The fuel rods are loaded and unloaded through the upper openings of the channels which are immersed in the coolant liquid, such as water. Unloading is accomplished by means of a coffer dam assembly having an outer sleeve which is placed in sealing relation around the upper opening. A radiation shield sleeve is disposed in and reciprocable through the coffer dam sleeve. A fuel rod engaging member operates through the axial bore in the radiation shield sleeve to withdraw the fuel rod from its position in the reactor coolant channel into the shield, the shield snd rod then being removed. Loading is accomplished in the reverse procedure.

  6. Catalytic reactor

    DOEpatents

    Aaron, Timothy Mark; Shah, Minish Mahendra; Jibb, Richard John

    2009-03-10

    A catalytic reactor is provided with one or more reaction zones each formed of set(s) of reaction tubes containing a catalyst to promote chemical reaction within a feed stream. The reaction tubes are of helical configuration and are arranged in a substantially coaxial relationship to form a coil-like structure. Heat exchangers and steam generators can be formed by similar tube arrangements. In such manner, the reaction zone(s) and hence, the reactor is compact and the pressure drop through components is minimized. The resultant compact form has improved heat transfer characteristics and is far easier to thermally insulate than prior art compact reactor designs. Various chemical reactions are contemplated within such coil-like structures such that as steam methane reforming followed by water-gas shift. The coil-like structures can be housed within annular chambers of a cylindrical housing that also provide flow paths for various heat exchange fluids to heat and cool components.

  7. NUCLEAR REACTOR

    DOEpatents

    Christy, R.F.

    1958-07-15

    A nuclear reactor of the homogeneous liquid fuel type is described wherein the fissionable isotope is suspended or dissolved in a liquid moderator such as water. The reactor core is comprised essentially of a spherical vessel for containing the reactive composition surrounded by a reflector, preferably of beryllium oxide. The reactive composition may be an ordinary water solution of a soluble salt of uranium, the quantity of fissionable isotope in solution being sufficient to provide a critical mass in the vessel. The liquid fuel is stored in a tank of non-crtttcal geometry below the reactor vessel and outside of the reflector and is passed from the tank to the vessel through a pipe connecting the two by air pressure means. Neutron absorbing control and safety rods are operated within slots in the reflector adjacent to the vessel.

  8. Bioconversion reactor

    DOEpatents

    McCarty, Perry L.; Bachmann, Andre

    1992-01-01

    A bioconversion reactor for the anaerobic fermentation of organic material. The bioconversion reactor comprises a shell enclosing a predetermined volume, an inlet port through which a liquid stream containing organic materials enters the shell, and an outlet port through which the stream exits the shell. A series of vertical and spaced-apart baffles are positioned within the shell to force the stream to flow under and over them as it passes from the inlet to the outlet port. The baffles present a barrier to the microorganisms within the shell causing them to rise and fall within the reactor but to move horizontally at a very slow rate. Treatment detention times of one day or less are possible.

  9. REACTOR CONTROL

    DOEpatents

    Fortescue, P.; Nicoll, D.

    1962-04-24

    A control system employed with a high pressure gas cooled reactor in which a control rod is positioned for upward and downward movement into the neutron field from a position beneath the reactor is described. The control rod is positioned by a coupled piston cylinder releasably coupled to a power drive means and the pressurized coolant is directed against the lower side of the piston. The coolant pressure is offset by a higher fiuid pressure applied to the upper surface of the piston and means are provided for releasing the higher pressure on the upper side of the piston so that the pressure of the coolant drives the piston upwardly, forcing the coupled control rod into the ncutron field of the reactor. (AEC)

  10. Bioconversion reactor

    SciTech Connect

    McCarty, P.L.; Bachmann, A.

    1992-02-25

    A bioconversion reactor is described for the anaerobic fermentation of organic material. The bioconversion reactor comprises a shell enclosing a predetermined volume, an inlet port through which a liquid stream containing organic materials enters the shell, and an outlet port through which the stream exits the shell. A series of vertical and spaced-apart baffles are positioned within the shell to force the stream to flow under and over them as it passes from the inlet to the outlet port. The baffles present a barrier to the microorganisms within the shell causing them to rise and fall within the reactor but to move horizontally at a very slow rate. Treatment detention times of one day or less are possible. 7 figs.

  11. NUCLEAR REACTOR

    DOEpatents

    Young, G.

    1963-01-01

    This patent covers a power-producing nuclear reactor in which fuel rods of slightly enriched U are moderated by heavy water and cooled by liquid metal. The fuel rods arranged parallel to one another in a circle are contained in a large outer closed-end conduit that extends into a tank containing the heavy water. Liquid metal is introduced into the large conduit by a small inner conduit that extends within the circle of fuel rods to a point near the lower closed end of the outer conduit. (AEC) Production Reactors

  12. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.; Weinberg, A.W.; Young, G.J.

    1958-04-15

    A nuclear reactor which uses uranium in the form of elongated tubes as fuel elements and liquid as a coolant is described. Elongated tubular uranium bodies are vertically disposed in an efficient neutron slowing agent, such as graphite, for example, to form a lattice structure which is disposed between upper and lower coolant tanks. Fluid coolant tubes extend through the uranium bodies and communicate with the upper and lower tanks and serve to convey the coolant through the uranium body. The reactor is also provided with means for circulating the cooling fluid through the coolant tanks and coolant tubes, suitable neutron and gnmma ray shields, and control means.

  13. The Usefulness of Edible and Medicinal Fabaceae in Argentine and Chilean Patagonia: Environmental Availability and Other Sources of Supply

    PubMed Central

    Molares, Soledad; Ladio, Ana

    2012-01-01

    Fabaceae is of great ethnobotanical importance in indigenous and urban communities throughout the world. This work presents a revision of the use of Fabaceae as a food and/or medicinal resource in Argentine-Chilean Patagonia. It is based on a bibliographical analysis of 27 ethnobotanical sources and catalogues of regional flora. Approximately 234 wild species grow in Patagonia, mainly (60%) in arid environments, whilst the remainder belong to Sub-Antarctic forest. It was found that 12.8% (30 species), mainly woody, conspicuous plants, are collected for food or medicines. Most of the species used grow in arid environments. Cultivation and purchase/barter enrich the Fabaceae offer, bringing it up to a total of 63 species. The richness of native and exotic species, and the existence of multiple strategies for obtaining these plants, indicates hybridization of knowledge and practices. Only 22% of the total species used are mentioned in bothcontexts of food and medicine, reflecting low-use complementation. This study suggests a significant ecological appearance and a high level of availability in shops and exchange networks in Patagonia, highlighting the need to consider the full set of environmental and socioeconomic factors in research related to the use and cultural importance of plants in regional contexts. PMID:22194774

  14. The peri-urban interface and house infestation with Triatoma infestans in the Argentine Chaco: an underreported process?

    PubMed

    Provecho, Yael M; Gaspe, M Sol; del Pilar Fernández, M; Enriquez, Gustavo F; Weinberg, Diego; Gürtler, Ricardo E

    2014-11-01

    Peri-urban infestations with triatomine bugs, their sources and their dynamics have rarely been investigated. Here, we corroborated the reported occurrence of Triatoma infestans in a peri-urban area and in neighbouring rural houses in Pampa del Indio, in the Argentine Chaco, and identified its putative sources using spatial analysis and demographic questionnaires. Peri-urban householders reported that 10% of their premises had triatomines, whereas T. infestans was collected by timed manual searches or community-based surveillance in only nine (3%) houses. Trypanosoma cruzi-infected T. infestans and Triatoma sordida were collected indoors only in peri-urban houses and were infected with TcV and TcI, respectively. The triatomines fed on chickens, cats and humans. Peri-urban infestations were most frequent in a squatter settlement and particularly within the recently built mud houses of rural immigrants, with large-sized households, more dogs and cats and more crowding. Several of the observed infestations were most likely associated with passive bug transport from other sources and with active bug dispersal from neighbouring foci. Thus, the households in the squatter settlement were at a greater risk of bug invasion and colonisation. In sum, the incipient process of domestic colonisation and transmission, along with persistent rural-to-urban migratory flows and unplanned urbanisation, indicate the need for active vector surveillance and control actions at the peri-urban interface of the Gran Chaco. PMID:25410997

  15. Modelling American trypanosomiasis in an endemic zone: application to the initial spread of household infection in the Argentine Chaco.

    PubMed

    Fabrizio, M C; Schweigmann, N J; Bartoloni, N J

    2014-12-01

    The complex dynamics of Trypanosoma cruzi infection (Chagas disease) involves different actors and multiple transmission routes. Based on the information currently available, here, we propose a new and more comprehensive model to better understand the dynamics of the infection. This mathematical deterministic model was formulated considering: (i) the three clinical forms in humans: acute, chronic indeterminate and chronic with determinate pathology, (ii) the three main modes of transmission in the human population: vector-borne, congenital and transfusional, (iii) populations of triatomines and dogs as the main domestic reservoirs of T. cruzi and (iv) open populations. A numerical simulation was also performed to estimate the initial spread of the infection in a typical rural household in the endemic zone of the Argentine Gran Chaco. We also analysed the incidence of infected individuals corresponding to each of the three species (humans/triatomines/dogs) over times until the appearance of the first case in the other species. The model predicts that, in the absence of control measures, a few infected individuals are sufficient for the establishment and dispersion of the infection in all the inhabitants of the household. The model proposed and the results obtained allow describing the consequences of the presence of infected individuals in any of the three species considered in the dynamics and the output of the infection. PMID:24528489

  16. Reconciling tectonic shortening, sedimentation and spatial patterns of erosion from 10Be paleo-erosion rates in the Argentine Precordillera

    NASA Astrophysics Data System (ADS)

    Val, Pedro; Hoke, Gregory D.; Fosdick, Julie C.; Wittmann, Hella

    2016-09-01

    The temporal evolution of erosion over million-year timescales is key to understand the development of mountain ranges and adjacent fold-and-thrust belts. While models of orogenic wedge dynamics predict an instantaneous response of erosion to pulses of rock uplift, stream-power based models predict that catchment-wide erosion maxima significantly lag behind a pulse of rock uplift. Here, we explore the relationships between rock uplift, erosion, and sediment deposition in the Argentine Precordillera fold-and-thrust belt at 30°S. Using a combination of 10Be-derived paleo-erosion rates, constraints on re-exposure using 26Al/10Be ratios, geomorphic observations and detrital zircon provenance, we demonstrate that the attainment of maximum upland erosion rates lags the maximum rate of deformation over million-year timescales. The magnitudes and causes of the erosional delays shed new light on the catchment erosional response to tectonic deformation and rock uplift in orogenic wedges.

  17. Relationship between beak morphological variables and body size and mantle length of male and female Argentine shortfin squid ( Illex argentinus)

    NASA Astrophysics Data System (ADS)

    Chen, Xinjun; Lu, Huajie; Liu, Bilin; Fang, Zhou

    2012-12-01

    Beak of cephalopod is an important hard tissue. Understanding the morphology of beak can yield critical information on the role of cephalopods in the ecosystem. The south patagonic stock of the Argentine shortfin squid, Illex argentinus, is not only one of the most important fishing targets, but also one of the most important species in the marine eco-system of the southwest Atlantic. A total of 430 samples of I. argentinus, including 229 females 103-346mm in mantle length (ML) and 201 males 140-298mm in ML, were collected from the area off the Exclusive Economic Zone of Argentinean waters by Chinese squid jigging vessels during February to May 2007. The morphology of their beaks was evaluated. The relationships between beak morphological variables and ML differed significantly among males and females. They could be best described by logarithmic functions for females and linear functions for males except for upper wing length (UWL) and lower rostrum length (LRL), which followed exponential functions in their relationships with ML. The results showed the sexual dimorphism in the relationship between ML and beak morphology for the south patagonic stock of I. argentinus. However, no significant difference was found between males and females in the relationships of beak morphological variables (except for UWL) versus body weight (BW), suggesting that the relationship between beak morphological variables and BW can be used for estimating the biomass consumed by their predators.

  18. The peri-urban interface and house infestation with Triatoma infestans in the Argentine Chaco: an underreported process?

    PubMed Central

    Provecho, Yael M; Gaspe, M Sol; del Pilar Fernández, M; Enriquez, Gustavo F; Weinberg, Diego; Gürtler, Ricardo E

    2014-01-01

    Peri-urban infestations with triatomine bugs, their sources and their dynamics have rarely been investigated. Here, we corroborated the reported occurrence of Triatoma infestans in a peri-urban area and in neighbouring rural houses in Pampa del Indio, in the Argentine Chaco, and identified its putative sources using spatial analysis and demographic questionnaires. Peri-urban householders reported that 10% of their premises had triatomines, whereas T. infestans was collected by timed manual searches or community-based surveillance in only nine (3%) houses. Trypanosoma cruzi-infected T. infestans and Triatoma sordida were collected indoors only in peri-urban houses and were infected with TcV and TcI, respectively. The triatomines fed on chickens, cats and humans. Peri-urban infestations were most frequent in a squatter settlement and particularly within the recently built mud houses of rural immigrants, with large-sized households, more dogs and cats and more crowding. Several of the observed infestations were most likely associated with passive bug transport from other sources and with active bug dispersal from neighbouring foci. Thus, the households in the squatter settlement were at a greater risk of bug invasion and colonisation. In sum, the incipient process of domestic colonisation and transmission, along with persistent rural-to-urban migratory flows and unplanned urbanisation, indicate the need for active vector surveillance and control actions at the peri-urban interface of the Gran Chaco. PMID:25410997

  19. Sonochemical Reactors.

    PubMed

    Gogate, Parag R; Patil, Pankaj N

    2016-10-01

    Sonochemical reactors are based on the generation of cavitational events using ultrasound and offer immense potential for the intensification of physical and chemical processing applications. The present work presents a critical analysis of the underlying mechanisms for intensification, available reactor configurations and overview of the different applications exploited successfully, though mostly at laboratory scales. Guidelines have also been presented for optimum selection of the important operating parameters (frequency and intensity of irradiation, temperature and liquid physicochemical properties) as well as the geometric parameters (type of reactor configuration and the number/position of the transducers) so as to maximize the process intensification benefits. The key areas for future work so as to transform the successful technique at laboratory/pilot scale into commercial technology have also been discussed. Overall, it has been established that there is immense potential for sonochemical reactors for process intensification leading to greener processing and economic benefits. Combined efforts from a wide range of disciplines such as material science, physics, chemistry and chemical engineers are required to harness the benefits at commercial scale operation. PMID:27573503

  20. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.

    1960-09-27

    A unit assembly is described for a neutronic reactor comprising a tube and plurality of spaced parallel sandwiches in the tube extending lengthwise thereof, each sandwich including a middle plate having a central opening for plutonium and other openings for fertile material at opposite ends of the plate.

  1. NEUTRONIC REACTOR

    DOEpatents

    Creutz, E.C.; Ohlinger, L.A.; Weinberg, A.M.; Wigner, E.P.; Young, G.J.

    1959-10-27

    BS>A reactor cooled by water, biphenyl, helium, or other fluid with provision made for replacing the fuel rods with the highest plutonium and fission product content without disassembling the entire core and for promptly cooling the rods after their replacement in order to prevent build-up of heat from fission product activity is described.

  2. Neutronic reactor

    DOEpatents

    Wende, Charles W. J.; Babcock, Dale F.; Menegus, Robert L.

    1983-01-01

    A nuclear reactor includes an active portion with fissionable fuel and neutron moderating material surrounded by neutron reflecting material. A control element in the active portion includes a group of movable rods constructed of neutron-absorbing material. Each rod is movable with respect to the other rods to vary the absorption of neutrons and effect control over neutron flux.

  3. Neutronic reactor

    DOEpatents

    Wende, Charles W. J.

    1976-08-17

    A safety rod for a nuclear reactor has an inner end portion having a gamma absorption coefficient and neutron capture cross section approximately equal to those of the adjacent shield, a central portion containing materials of high neutron capture cross section and an outer end portion having a gamma absorption coefficient at least equal to that of the adjacent shield.

  4. Neutronic reactor

    DOEpatents

    Carleton, John T.

    1977-01-25

    A graphite-moderated nuclear reactor includes channels between blocks of graphite and also includes spacer blocks between adjacent channeled blocks with an axis of extension normal to that of the axis of elongation of the channeled blocks to minimize changes in the physical properties of the graphite as a result of prolonged neutron bombardment.

  5. NEUTRONIC REACTOR

    DOEpatents

    Wade, E.J.

    1958-09-16

    This patent relates to a reflector means for a neutronic reactor. A reflector comprised of a plurality of vertically movable beryllium control members is provided surrounding the sides of the reactor core. An absorber of fast neutrons comprised of natural uramum surrounds the reflector. An absorber of slow neutrons surrounds the absorber of fast neutrons and is formed of a plurality of beryllium blocks having natural uranium members distributcd therethrough. in addition, a movable body is positioned directly below the core and is comprised of a beryllium reflector and an absorbing member attached to the botiom thereof, the absorbing member containing a substance selected from the goup consisting of natural urantum and Th/sup 232/.

  6. REACTOR MONITORING

    DOEpatents

    Bugbee, S.J.; Hanson, V.F.; Babcock, D.F.

    1959-02-01

    A neutron density inonitoring means for reactors is described. According to this invention a tunnel is provided beneath and spaced from the active portion of the reactor and extends beyond the opposite faces of the activc portion. Neutron beam holes are provided between the active portion and the tunnel and open into the tunnel near the middle thereof. A carriage operates back and forth in the tunnel and is adapted to convey a neutron detector, such as an ion chamber, and position it beneath one of the neutron beam holes. This arrangement affords convenient access of neutron density measuring instruments to a location wherein direct measurement of neutron density within the piles can be made and at the same time affords ample protection to operating personnel.

  7. REACTOR UNLOADING

    DOEpatents

    Leverett, M.C.

    1958-02-18

    This patent is related to gas cooled reactors wherein the fuel elements are disposed in vertical channels extending through the reactor core, the cooling gas passing through the channels from the bottom to the top of the core. The invention is a means for unloading the fuel elements from the core and comprises dump values in the form of flat cars mounted on wheels at the bottom of the core structure which support vertical stacks of fuel elements. When the flat cars are moved, either manually or automatically, for normal unloading purposes, or due to a rapid rise in the reproduction ratio within the core, the fuel elements are permtted to fall by gravity out of the core structure thereby reducing the reproduction ratio or stopping the reaction as desired.

  8. Nuclear reactor

    DOEpatents

    Wade, Elman E.

    1979-01-01

    A nuclear reactor including two rotatable plugs and a positive top core holddown structure. The top core holddown structure is divided into two parts: a small core cover, and a large core cover. The small core cover, and the upper internals associated therewith, are attached to the small rotating plug, and the large core cover, with its associated upper internals, is attached to the large rotating plug. By so splitting the core holddown structures, under-the-plug refueling is accomplished without the necessity of enlarging the reactor pressure vessel to provide a storage space for the core holddown structure during refueling. Additionally, the small and large rotating plugs, and their associated core covers, are arranged such that the separation of the two core covers to permit rotation is accomplished without the installation of complex lifting mechanisms.

  9. NUCLEAR REACTOR

    DOEpatents

    Treshow, M.

    1958-08-19

    A neuclear reactor is described of the heterogeneous type and employing replaceable tubular fuel elements and heavy water as a coolant and moderator. A pluraltty of fuel tubesa having their axes parallel, extend through a tank type pressure vessel which contatns the liquid moderator. The fuel elements are disposed within the fuel tubes in the reaetive portion of the pressure vessel during normal operation and the fuel tubes have removable plug members at each end to permit charging and discharging of the fuel elements. The fuel elements are cylindrical strands of jacketed fissionable material having helical exterior ribs. A bundle of fuel elements are held within each fuel tube with their longitudinal axes parallel, the ribs serving to space them apart along their lengths. Coolant liquid is circulated through the fuel tubes between the spaced fuel elements. Suitable control rod and monitoring means are provided for controlling the reactor.

  10. NUCLEAR REACTOR

    DOEpatents

    Grebe, J.J.

    1959-12-15

    A reactor which is particularly adapted tu serve as a heat source for a nuclear powered alrcraft or rocket is described. The core of this reactor consists of a porous refractory modera;or body which is impregnated with fissionable nuclei. The core is designed so that its surface forms tapered inlet and outlet ducts which are separated by the porous moderator body. In operation a gaseous working fluid is circulated through the inlet ducts to the surface of the moderator, enters and passes through the porous body, and is heated therein. The hot gas emerges into the outlet ducts and is available to provide thrust. The principle advantage is that tremendous quantities of gas can be quickly heated without suffering an excessive pressure drop.

  11. NUCLEAR REACTORS

    DOEpatents

    Koch, L.J.; Rice, R.E. Jr.; Denst, A.A.; Rogers, A.J.; Novick, M.

    1961-12-01

    An active portion assembly for a fast neutron reactor is described wherein physical distortions resulting in adverse changes in the volume-to-mass ratio are minimized. A radially expandable locking device is disposed within a cylindrical tube within each fuel subassembly within the active portion assembly, and clamping devices expandable toward the center of the active portion assembly are disposed around the periphery thereof. (AEC)

  12. NUCLEAR REACTOR

    DOEpatents

    Grebe, J.J.

    1961-01-24

    A core structure for neutronic reactors adapted for the propulsion of aircraft and rockets is offered. The core is designed for cooling by gaseous media, and comprises a plurality of hollow tapered tubular segments of a porous moderating material impregniated with fissionable fuel nested about a common axis. Alternate ends of the segments are joined. In operation a coolant gas passes through the porous structure and is heated.

  13. NUCLEAR REACTORS

    DOEpatents

    Long, E.; Ashby, J.W.

    1958-09-16

    ABS>A graphite moderator structure is presented for a nuclear reactor compriscd of an assembly of similarly orientated prismatic graphite blocks arranged on spaced longitudinal axes lying in common planes wherein the planes of the walls of the blocks are positioned so as to be twisted reintive to the planes of said axes so thatthe unlmpeded dtrect paths in direction wholly across the walls of the blocks are limited to the width of the blocks plus spacing between the blocks.

  14. REACTOR CONTROL

    DOEpatents

    Ruano, W.J.

    1957-12-10

    This patent relates to nuclear reactors of the type which utilize elongited rod type fuel elements immersed in a liquid moderator and shows a design whereby control of the chain reaction is obtained by varying the amount of moderator or reflector material. A central tank for containing liquid moderator and fuel elements immersed therein is disposed within a surrounding outer tank providing an annular space between the two tanks. This annular space is filled with liquid moderator which functions as a reflector to reflect neutrons back into the central reactor tank to increase the reproduction ratio. Means are provided for circulating and cooling the moderator material in both tanks and additional means are provided for controlling separately the volume of moderator in each tank, which latter means may be operated automatically by a neutron density monitoring device. The patent also shows an arrangement for controlling the chain reaction by injecting and varying an amount of poisoning material in the moderator used in the reflector portion of the reactor.

  15. A new species of Dendromonocotyle Hargis, 1955 (Monogenea: Monocotylidae) from the skin of Zearaja chilensis (Guichenot) (Rajiformes: Rajidae) from the Argentine Sea.

    PubMed

    Irigoitia, Manuel M; Chisholm, Leslie A; Timi, Juan T

    2016-05-01

    Dendromonocotyle rajidicola n. sp. is described from the dorsal surface of the yellownose skate Zearaja chilensis (Guichenot) (Rajiformes) caught on the Argentine shelf. Dendromonocotyle rajidicola n. sp. can be distinguished from the other 17 species in the genus by the morphology of the distal portion of the male copulatory organ and by the unique morphology of the sclerotised proximal portion of the vagina. This is the first species of Dendromonocotyle to be described from a host in the Rajiformes and also the first record of this genus in the southwestern Atlantic Ocean. PMID:27095665

  16. Effect of latitudinal gradient and impact of logging on genetic diversity of Cedrela lilloi along the Argentine Yungas Rainforest.

    PubMed

    Inza, Maria V; Zelener, Noga; Fornes, Luis; Gallo, Leonardo A

    2012-11-01

    Cedrela lilloi C. DC. (cedro coya, Meliaceae), an important south American timber species, has been historically overexploited through selective logging in Argentine Yungas Rainforest. Management and conservation programs of the species require knowledge of its genetic variation patterns; however, no information is available. Molecular genetic variability of the species was characterized to identify high-priority populations for conservation and domestication purposes. Fourteen native populations (160 individuals) along a latitudinal gradient and with different logging's intensities were assessed by 293 polymorphic AFLP (amplified fragment length polymorphism) markers. Genetic diversity was low (Ht = 0.135), according to marginal location of the species in Argentina. Most of the diversity was distributed within populations (87%). Northern populations showed significant higher genetic diversity (R(2)= 0.69) that agreed with latitudinal pattern of distribution of taxonomic diversity in the Yungas. Three clusters were identified by Bayesian analysis in correspondence with northern, central, and southern Yungas. An analysis of molecular variance (AMOVA) revealed significant genetic differences among latitudinal clusters even when logging (Φ(RT) = 0.07) and unlogging populations (Φ(PT) = 0.10) were separately analyzed. Loss of genetic diversity with increasing logging intensity was observed between neighboring populations with different disturbance (Φ(PT) = 0.03-0.10). Bottlenecks in disturbed populations are suggested as the main cause. Our results emphasize both: the necessity of maintaining the genetic diversity in protected areas that appear as possible long-term refuges of the species; and to rescue for the national system of protected areas some high genetic diversity populations that are on private fields. PMID:23170208

  17. Interactive Effects of Large- and Small-Scale Sources of Feral Honey-Bees for Sunflower in the Argentine Pampas

    PubMed Central

    Sáez, Agustín; Sabatino, Malena; Aizen, Marcelo A.

    2012-01-01

    Pollinators for animal pollinated crops can be provided by natural and semi-natural habitats, ranging from large vegetation remnants to small areas of non-crop land in an otherwise highly modified landscape. It is unknown, however, how different small- and large-scale habitat patches interact as pollinator sources. In the intensively managed Argentine Pampas, we studied the additive and interactive effects of large expanses (up to 2200 ha) of natural habitat, represented by untilled isolated “sierras”, and narrow (3–7 m wide) strips of semi-natural habitat, represented by field margins, as pollinator sources for sunflower (Helianthus annus). We estimated visitation rates by feral honey-bees, Apis mellifera, and native flower visitors (as a group) at 1, 5, 25, 50 and 100 m from a field margin in 17 sunflower fields 0–10 km distant from the nearest sierra. Honey-bees dominated the pollinator assemblage accounting for >90% of all visits to sunflower inflorescences. Honey-bee visitation was strongly affected by proximity to the sierras decreasing by about 70% in the most isolated fields. There was also a decline in honey-bee visitation with distance from the field margin, which was apparent with increasing field isolation, but undetected in fields nearby large expanses of natural habitat. The probability of observing a native visitor decreased with isolation from the sierras, but in other respects visitation by flower visitors other than honey-bees was mostly unaffected by the habitat factors assessed in this study. Overall, we found strong hierarchical and interactive effects between the study large and small-scale pollinator sources. These results emphasize the importance of preserving natural habitats and managing actively field verges in the absence of large remnants of natural habitat for improving pollinator services. PMID:22303477

  18. Effect of latitudinal gradient and impact of logging on genetic diversity of Cedrela lilloi along the Argentine Yungas Rainforest

    PubMed Central

    Inza, Maria V; Zelener, Noga; Fornes, Luis; Gallo, Leonardo A

    2012-01-01

    Cedrela lilloi C. DC. (cedro coya, Meliaceae), an important south American timber species, has been historically overexploited through selective logging in Argentine Yungas Rainforest. Management and conservation programs of the species require knowledge of its genetic variation patterns; however, no information is available. Molecular genetic variability of the species was characterized to identify high-priority populations for conservation and domestication purposes. Fourteen native populations (160 individuals) along a latitudinal gradient and with different logging's intensities were assessed by 293 polymorphic AFLP (amplified fragment length polymorphism) markers. Genetic diversity was low (Ht = 0.135), according to marginal location of the species in Argentina. Most of the diversity was distributed within populations (87%). Northern populations showed significant higher genetic diversity (R2= 0.69) that agreed with latitudinal pattern of distribution of taxonomic diversity in the Yungas. Three clusters were identified by Bayesian analysis in correspondence with northern, central, and southern Yungas. An analysis of molecular variance (AMOVA) revealed significant genetic differences among latitudinal clusters even when logging (ΦRT = 0.07) and unlogging populations (ΦPT = 0.10) were separately analyzed. Loss of genetic diversity with increasing logging intensity was observed between neighboring populations with different disturbance (ΦPT = 0.03–0.10). Bottlenecks in disturbed populations are suggested as the main cause. Our results emphasize both: the necessity of maintaining the genetic diversity in protected areas that appear as possible long-term refuges of the species; and to rescue for the national system of protected areas some high genetic diversity populations that are on private fields. PMID:23170208

  19. Interactive effects of large- and small-scale sources of feral honey-bees for sunflower in the Argentine Pampas.

    PubMed

    Sáez, Agustín; Sabatino, Malena; Aizen, Marcelo A

    2012-01-01

    Pollinators for animal pollinated crops can be provided by natural and semi-natural habitats, ranging from large vegetation remnants to small areas of non-crop land in an otherwise highly modified landscape. It is unknown, however, how different small- and large-scale habitat patches interact as pollinator sources. In the intensively managed Argentine Pampas, we studied the additive and interactive effects of large expanses (up to 2200 ha) of natural habitat, represented by untilled isolated "sierras", and narrow (3-7 m wide) strips of semi-natural habitat, represented by field margins, as pollinator sources for sunflower (Helianthus annus). We estimated visitation rates by feral honey-bees, Apis mellifera, and native flower visitors (as a group) at 1, 5, 25, 50 and 100 m from a field margin in 17 sunflower fields 0-10 km distant from the nearest sierra. Honey-bees dominated the pollinator assemblage accounting for >90% of all visits to sunflower inflorescences. Honey-bee visitation was strongly affected by proximity to the sierras decreasing by about 70% in the most isolated fields. There was also a decline in honey-bee visitation with distance from the field margin, which was apparent with increasing field isolation, but undetected in fields nearby large expanses of natural habitat. The probability of observing a native visitor decreased with isolation from the sierras, but in other respects visitation by flower visitors other than honey-bees was mostly unaffected by the habitat factors assessed in this study. Overall, we found strong hierarchical and interactive effects between the study large and small-scale pollinator sources. These results emphasize the importance of preserving natural habitats and managing actively field verges in the absence of large remnants of natural habitat for improving pollinator services. PMID:22303477

  20. Faulting and erosion in the Argentine Precordillera during changes in subduction regime: Reconciling bedrock cooling and detrital records

    NASA Astrophysics Data System (ADS)

    Fosdick, Julie C.; Carrapa, Barbara; Ortíz, Gustavo

    2015-12-01

    The Argentine Precordillera is an archetypal retroarc fold-and-thrust belt that records tectonics associated with changing subduction regimes. The interactions between exhumation and faulting in the Precordillera were investigated using apatite and zircon (U-Th-Sm)/He and apatite fission track thermochronometry from the Precordillera and adjacent geologic domains. Inverse modeling of thermal histories constrains eastward in-sequence rock cooling associated with deformation and erosion from 18 to 2 Ma across the Central Precordillera tracking thrusting during this time. The youngest AHe ages (5-2 Ma) and highest erosion rates are located in the eastern and western extremities of the Precordillera and indicate that recent denudation is concentrated at its structural boundaries. Moreover, synchronous rapid Pliocene cooling of the Frontal Cordillera, Eastern Precordillera, and Sierra del Valle Fértil was coeval with initiation of basement-involved faulting in the foreland. Detrital zircon U-Pb geochronology from the ca. 16-8.1 Ma Bermejo foreland basin strata suggests fluvial connectivity westward beyond the Frontal Cordillera to the Main Cordillera and Coast Range followed by an important shift in sediment provenance at ca. 10 Ma. At this time, we suggest that a substantial decrease in Permo-Triassic igneous sources in the Frontal Cordillera and concurrent increase in recycled zircons signatures of Paleozoic strata are best explained by uplift and erosion of the Precordillera during widening of the thrust-belt. Bedrock thermochronology and modeling indicate a 2-6 Myr lag time between faulting-related cooling in the hinterland and the detrital record of deformation in the foreland basin, suggesting that for tectonically active semi-arid settings, bedrock cooling may be more sensitive to onset of faulting. We suggest that high erosion rates in the Frontal Cordillera and Eastern Precordillera are associated with increased interplate coupling during shallowing of the

  1. Is the Invasive Species Listronotus bonariensis (Kuschel) (Coleoptera: Curculionidae) (Argentine Stem Weevil) a Threat to New Zealand Natural Grassland Ecosystems?

    PubMed Central

    Barratt, Barbara I. P.; Barton, Diane M.; Philip, Bruce A.; Ferguson, Colin M.; Goldson, Stephen L.

    2016-01-01

    Listronotus bonariensis (Argentine stem weevil) is a stem-boring weevil that has become a major pasture pest in New Zealand, and cool climate turf grass in Australia. This species is also frequently found in native tussock grassland in New Zealand. Laboratory and field trials were established to determine the risk posed to both seedlings and established plants of three native grass species compared to what happens with a common host of this species, hybrid ryegrass (L. perenne X L. multiflorum). Adult weevil feeding damage scores were higher on Poa colensoi and Festuca novae-zelandiae than Chionochloa rigida. Oviposition was lower on P. colensoi than hybrid ryegrass, and no eggs were laid on F. novae-zelandiae. In field trials using the same four species established as spaced plants L. bonariensis laid more eggs per tiller in ryegrass in a low altitude pasture site than in ryegrass in a higher altitude site. No eggs were found on the three native grass species at the tussock sites, and only low numbers were found on other grasses at the low altitude pasture site. Despite this, numbers of adult weevils were extracted from the plants in the field trials. These may have comprised survivors of the original weevils added to the plants, together with new generation weevils that had emerged during the experiment. Irrespective, higher numbers were recovered from the tussock site plants than from those from the pasture site. It was concluded that L. bonariensis is likely to have little overall impact, but a greater impact on native grass seedling survival than on established plants. PMID:27507979

  2. Nuclear reactor

    DOEpatents

    Pennell, William E.; Rowan, William J.

    1977-01-01

    A nuclear reactor in which the core components, including fuel-rod assemblies, control-rod assemblies, fertile rod-assemblies, and removable shielding assemblies, are supported by a plurality of separate inlet modular units. These units are referred to as inlet module units to distinguish them from the modules of the upper internals of the reactor. The modular units are supported, each removable independently of the others, in liners in the supporting structure for the lower internals of the reactor. The core assemblies are removably supported in integral receptacles or sockets of the modular units. The liners, units, sockets and assmblies have inlet openings for entry of the fluid. The modular units are each removably mounted in the liners with fluid seals interposed between the opening in the liner and inlet module into which the fluid enters and the upper and lower portion of the liner. Each assembly is similarly mounted in a corresponding receptacle with fluid seals interposed between the openings where the fluid enters and the lower portion of the receptacle or fitting closely in these regions. As fluid flows along each core assembly a pressure drop is produced along the fluid so that the fluid which emerges from each core assembly is at a lower pressure than the fluid which enters the core assembly. However because of the seals interposed in the mountings of the units and assemblies the pressures above and below the units and assemblies are balanced and the units are held in the liners and the assemblies are held in the receptacles by their weights as they have a higher specific gravity than the fluid. The low-pressure spaces between each module and its liner and between each core assembly and its module is vented to the low-pressure regions of the vessel to assure that fluid which leaks through the seals does not accumulate and destroy the hydraulic balance.

  3. ELECTRONUCLEAR REACTOR

    DOEpatents

    Lawrence, E.O.; McMillan, E.M.; Alvarez, L.W.

    1960-04-19

    An electronuclear reactor is described in which a very high-energy particle accelerator is employed with appropriate target structure to produce an artificially produced material in commercial quantities by nuclear transformations. The principal novelty resides in the combination of an accelerator with a target for converting the accelerator beam to copious quantities of low-energy neutrons for absorption in a lattice of fertile material and moderator. The fertile material of the lattice is converted by neutron absorption reactions to an artificially produced material, e.g., plutonium, where depleted uranium is utilized as the fertile material.

  4. REACTOR COMPONETN

    DOEpatents

    Creutz, E.C.

    1959-10-27

    A reactor fuel element comprised of a slug of fissionable material disposed in a sheath of corrosion resistantmaterial is described. The sheath is in the form of a tubular container closed at one end and is in tight-fitting engagement with the peripheral sunface of the slug. An inner cap is insented into the open end of the sheath against the slug, which end is then bent around the inner cap and welded thereto. An outer cap is then welded around its peripheny to the bent portion of the container.

  5. NUCLEAR REACTORS

    DOEpatents

    Long, E.; Ashley, J.W.

    1958-12-16

    A graphite moderator structure is described for a gas-cooled nuclear reactor having a vertical orlentation wherein the structure is physically stable with regard to dlmensional changes due to Wigner growth properties of the graphite, and leakage of coolant gas along spaces in the structure is reduced. The structure is comprised of stacks of unlform right prismatic graphite blocks positioned in layers extending in the direction of the lengths of the blocks, the adjacent end faces of the blocks being separated by pairs of tiles. The blocks and tiles have central bores which are in alignment when assembled and are provided with cooperatlng keys and keyways for physical stability.

  6. Nuclear Reactors. Revised.

    ERIC Educational Resources Information Center

    Hogerton, John F.

    This publication is one of a series of information booklets for the general public published by the United States Atomic Energy Commission. Among the topics discussed are: How Reactors Work; Reactor Design; Research, Teaching, and Materials Testing; Reactors (Research, Teaching and Materials); Production Reactors; Reactors for Electric Power…

  7. Activities with Argentina. Spring 1999. A U.S. Department of Energy Cooperative Program with the National Atomic Energy Commission of the Argentine Republic

    SciTech Connect

    1999-06-01

    In 1989, the US Department of Energy (DOE) responded to the need to redirect resources from weapons production to environmental restoration and waste management by establishing the Office of Environmental Management (EM) and delegated to this office the responsibility of cleaning up the US nuclear weapons complex. Now in its eight year, EM`s mission has three central facets: (1) to assess, remediate, and monitor contaminated sites and facilities; (2) to store, treat, and dispose of waste from past and current operations; and (3) to develop and implement innovative technologies for environmental cleanup. To this end, EM has established domestic and international cooperative technology development programs, including one with the Republic of Argentina. Cooperating with Argentine scientific institutes and industries meets US cleanup objectives by: (1) identifying and accessing Argentine EM-related technologies, thereby leveraging investments and providing cost-savings; (2) improving access to technical information, scientific expertise, and technologies applicable to EM needs; and (3) fostering the development of innovative environmental technologies by increasing US private sector opportunities in Argentina in EM-related areas.

  8. MLPA analysis of an Argentine cohort of patients with dystrophinopathy: Association of intron breakpoints hot spots with STR abundance in DMD gene.

    PubMed

    Luce, Leonela N; Dalamon, Viviana; Ferrer, Marcela; Parma, Diana; Szijan, Irene; Giliberto, Florencia

    2016-06-15

    Dystrophinopathies are X-linked recessive diseases caused by mutations in the DMD gene. Our objective was to identify mutations in this gene by Multiplex Ligation Probe Amplification (MLPA), to confirm the clinical diagnosis and determine the carrier status of at-risk relatives. Also, we aimed to characterize the Dystrophinopathies argentine population and the DMD gene. We analyzed a cohort of 121 individuals (70 affected boys, 11 symptomatic women, 37 at-risk women and 3 male villus samples). The MLPA technique identified 56 mutations (45 deletions, 9 duplications and 2 point mutations). These results allowed confirming the clinical diagnosis in 63% (51/81) of patients and symptomatic females. We established the carrier status of 54% (20/37) of females at-risk and 3 male villus samples. We could establish an association between the most frequent deletion intron breakpoints and the abundance of dinucleotide microsatellites loci, despite the underlying mutational molecular mechanism remains to be elucidated. The MLPA demonstrate, again, to be the appropriate first mutation screening methodology for molecular diagnosis of Dystrophinopathies. The reported results permitted to characterize the Dystrophinopathies argentine population and lead to better understanding of the genetic and molecular basis of rearrangements in the DMD gene, useful information for the gene therapies being developed. PMID:27206868

  9. Spatial patterns of copepod biodiversity in relation to a tidal front system in the main spawning and nursery area of the Argentine hake Merluccius hubbsi

    NASA Astrophysics Data System (ADS)

    Temperoni, B.; Viñas, M. D.; Martos, P.; Marrari, M.

    2014-11-01

    Copepods play an important role in marine ecosystems as a direct link of energy transfer between primary producers and higher trophic level consumers, such as fish. In the Argentine Sea, the Patagonian stock of Argentine hake Merluccius hubbsi spawns from late austral spring (December) to early autumn (April) in the northern Patagonian shelf region (43°-45°30‧S), in association with a highly productive tidal front system. Since hake larvae prey mainly upon copepods, the objective of this study was to assess the spatial variability in the abundance and diversity of these potential food items in different sectors of the front, as one of the possible factors affecting hake recruitment success. Two complementary mesh sizes (67 and 300 μm) were used to accurately target the entire copepod size spectrum. The copepod community was dominated by developmental stages < 1 mm in total length (eggs, nauplii, copepodites of cyclopoids and calanoids), and adults of the species Oithona helgolandica, Microsetella norvegica, Ctenocalanus vanus and Drepanopus forcipatus. Their spatial distribution was highly influenced by the across-shelf characteristics of the tidal front system, highlighting the impact of environmental features, mainly bottom temperature and salinity, in shaping the community. Abundances were higher in the transitional relative to the stratified sector of the system. Such sector would provide the appropriate conditions to sustain M. hubbsi larval growth resulting from high availability of adequate prey, the suitable thermal ranges, and the existence of retention mechanisms.

  10. Hybrid adsorptive membrane reactor

    DOEpatents

    Tsotsis, Theodore T.; Sahimi, Muhammad; Fayyaz-Najafi, Babak; Harale, Aadesh; Park, Byoung-Gi; Liu, Paul K. T.

    2011-03-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  11. Hybrid adsorptive membrane reactor

    NASA Technical Reports Server (NTRS)

    Tsotsis, Theodore T. (Inventor); Sahimi, Muhammad (Inventor); Fayyaz-Najafi, Babak (Inventor); Harale, Aadesh (Inventor); Park, Byoung-Gi (Inventor); Liu, Paul K. T. (Inventor)

    2011-01-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  12. Control Means for Reactor

    DOEpatents

    Manley, J. H.

    1961-06-27

    An apparatus for controlling a nuclear reactor includes a tank just below the reactor, tubes extending from the tank into the reactor, and a thermally expansible liquid neutron absorbent material in the tank. The liquid in the tank is exposed to a beam of neutrons from the reactor which heats the liquid causing it to expand into the reactor when the neutron flux in the reactor rises above a predetermincd danger point. Boron triamine may be used for this purpose.

  13. NEUTRONIC REACTOR

    DOEpatents

    Stewart, H.B.

    1958-12-23

    A nuclear reactor of the type speclfically designed for the irradiation of materials is discussed. In this design a central cyllndrical core of moderating material ls surrounded by an active portlon comprlsed of an annular tank contalning fissionable material immersed ln a liquid moderator. The active portion ls ln turn surrounded by a reflector, and a well ls provided in the center of the core to accommodate the materlals to be irradiated. The over-all dimensions of the core ln at least one plane are equal to or greater than twice the effective slowing down length and equal to or less than twlce the effective diffuslon length for neutrons in the core materials.

  14. NEUTRONIC REACTOR

    DOEpatents

    Daniels, F.

    1962-12-18

    A power plant is described comprising a turbine and employing round cylindrical fuel rods formed of BeO and UO/sub 2/ and stacks of hexagonal moderator blocks of BeO provided with passages that loosely receive the fuel rods so that coolant may flow through the passages over the fuels to remove heat. The coolant may be helium or steam and fiows through at least one more heat exchanger for producing vapor from a body of fluid separate from the coolant, which fluid is to drive the turbine for generating electricity. By this arrangement the turbine and directly associated parts are free of particles and radiations emanating from the reactor. (AEC)

  15. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.

    1957-09-17

    A reactor of the type having coolant liquid circulated through clad fuel elements geometrically arranged in a solid moderator, such as graphite, is described. The core is enclosed in a pressure vessel and suitable shielding, wherein means is provided for circulating vapor through the core to superheat the same. This is accomplished by drawing off the liquid which has been heated in the core due to the fission of the fuel, passing it to a nozzle within a chamber where it flashes into a vapor, and then passing the vapor through separate tubes extending through the moderator to pick up more heat developed in the core due to the fission of the fuel, thereby producing superheated vapor.

  16. Nuclear reactor

    DOEpatents

    Yant, Howard W.; Stinebiser, Karl W.; Anzur, Gregory C.

    1977-01-01

    A nuclear reactor, particularly a liquid-metal breeder reactor, whose upper internals include outlet modules for channeling the liquid-metal coolant from selected areas of the outlet of the core vertically to the outlet plenum. The modules are composed of a highly-refractory, high corrosion-resistant alloy, for example, INCONEL-718. Each module is disposed to confine and channel generally vertically the coolant emitted from a subplurality of core-component assemblies. Each module has a grid with openings, each opening disposed to receive the coolant from an assembly of the subplurality. The grid in addition serves as a holdown for the assemblies of the corresponding subplurality preventing their excessive ejection upwardly from the core. In the region directly over the core the outlet modules are of such peripheral form that they nest forming a continuum over the core-component assemblies whose outlet coolant they confine. Each subassembly includes a chimney which confines the coolant emitted by its corresponding subassemblies to generally vertical flow between the outlet of the core and the outlet plenum. Each subplurality of assemblies whose emitted coolant is confined by an outlet module includes assemblies which emit lower-temperature coolant, for example, a control-rod assembly, or fertile assemblies, and assemblies which emit coolant of substantially higher temperature, for example, fuel-rod assemblies. The coolants of different temperatures are mixed in the chimneys reducing the effect of stripping (hot-cold temperature fluctuations) on the remainder of the upper internals which are composed typically of AISI-304 or AISI-316 stainless steel.

  17. Characterizing and predicting species distributions across environments and scales: Argentine ant occurrences in the eye of the beholder

    USGS Publications Warehouse

    Menke, S.B.; Holway, D.A.; Fisher, R.N.; Jetz, W.

    2009-01-01

    Aim: Species distribution models (SDMs) or, more specifically, ecological niche models (ENMs) are a useful and rapidly proliferating tool in ecology and global change biology. ENMs attempt to capture associations between a species and its environment and are often used to draw biological inferences, to predict potential occurrences in unoccupied regions and to forecast future distributions under environmental change. The accuracy of ENMs, however, hinges critically on the quality of occurrence data. ENMs often use haphazardly collected data rather than data collected across the full spectrum of existing environmental conditions. Moreover, it remains unclear how processes affecting ENM predictions operate at different spatial scales. The scale (i.e. grain size) of analysis may be dictated more by the sampling regime than by biologically meaningful processes. The aim of our study is to jointly quantify how issues relating to region and scale affect ENM predictions using an economically important and ecologically damaging invasive species, the Argentine ant (Linepithema humile). Location: California, USA. Methods: We analysed the relationship between sampling sufficiency, regional differences in environmental parameter space and cell size of analysis and resampling environmental layers using two independently collected sets of presence/absence data. Differences in variable importance were determined using model averaging and logistic regression. Model accuracy was measured with area under the curve (AUC) and Cohen's kappa. Results: We first demonstrate that insufficient sampling of environmental parameter space can cause large errors in predicted distributions and biological interpretation. Models performed best when they were parametrized with data that sufficiently sampled environmental parameter space. Second, we show that altering the spatial grain of analysis changes the relative importance of different environmental variables. These changes apparently result

  18. Vestiges of an Ordovician west-vergent thin-skinned Ocloyic thrust belt in the Argentine Precordillera, southern Central Andes

    NASA Astrophysics Data System (ADS)

    Thomas, William A.; Astini, Ricardo A.

    2007-08-01

    Collision of the down-going, Laurentia-derived Argentine Precordillera terrane with the Gondwanan margin drove the Ordovician Ocloyic orogeny, including subduction volcanism, metamorphism, and top-to-west shearing east of the Precordillera. In the Precordillera, above passive-margin carbonates (Lower Ordovician San Juan Limestone and older carbonates), a Middle to Upper Ordovician westward-prograding synorogenic clastic wedge of black shale (Gualcamayo Shale) and coarser clastic sediment (Las Vacas Conglomerate and Trapiche Formation) fills a peripheral foreland basin. New research has identified vestiges of a west-directed thin-skinned Ocloyic foreland thrust belt that has been fragmented by east-directed Andean thrusting. The El Corral thrust sheet, with hanging-wall detachment in the San Juan Limestone, extends over a west-directed footwall frontal ramp and extensive flat to low-angle footwall cutoff in the Gualcamayo and Las Vacas formations. Las Vacas conglomerates in the footwall include olistoliths (10-m scale) exclusively of San Juan Limestone and Gualcamayo Shale; the beds in some olistoliths are folded. The advancing El Corral thrust sheet successively supplied and overrode the stratigraphically restricted olistoliths. In the El Corral footwall, tight west-vergent folds and faults within an anticlinorium in the San Juan Limestone and Gualcamayo Shale suggest a deeper (unexposed) thrust fault, the Los Celestitos fault. West of the anticlinorium, easterly dip (restored to remove Andean deformation) beneath an angular unconformity between Las Vacas and Trapiche beds is consistent geometrically with the trailing limb of a west-vergent fault-propagation anticline in the hanging wall of the subsurface Los Celestitos fault. The same angular unconformity truncates the El Corral fault and hanging-wall strata. In the Trapiche Formation, contrasting sedimentary facies from sandy turbidites westward to limestone-clast megabeds and olistoliths suggest another frontal

  19. Reactor and method of operation

    DOEpatents

    Wheeler, John A.

    1976-08-10

    A nuclear reactor having a flattened reactor activity curve across the reactor includes fuel extending over a lesser portion of the fuel channels in the central portion of the reactor than in the remainder of the reactor.

  20. Reactor safety method

    DOEpatents

    Vachon, Lawrence J.

    1980-03-11

    This invention relates to safety means for preventing a gas cooled nuclear reactor from attaining criticality prior to start up in the event the reactor core is immersed in hydrogenous liquid. This is accomplished by coating the inside surface of the reactor coolant channels with a neutral absorbing material that will vaporize at the reactor's operating temperature.

  1. NEUTRONIC REACTOR MANIPULATING DEVICE

    DOEpatents

    Ohlinger, L.A.

    1962-08-01

    A cable connecting a control rod in a reactor with a motor outside the reactor for moving the rod, and a helical conduit in the reactor wall, through which the cable passes are described. The helical shape of the conduit prevents the escape of certain harmful radiations from the reactor. (AEC)

  2. Nuclear reactor

    DOEpatents

    Thomson, Wallace B.

    2004-03-16

    A nuclear reactor comprising a cylindrical pressure vessel, an elongated annular core centrally disposed within and spaced from the pressure vessel, and a plurality of ducts disposed longitudinally of the pressure vessel about the periphery thereof, said core comprising an annular active portion, an annular reflector just inside the active portion, and an annular reflector just outside the active a portion, said annular active portion comprising rectangular slab, porous fuel elements radially disposed around the inner reflector and extending the length of the active portion, wedge-shaped, porous moderator elements disposed adjacent one face of each fuel element and extending the length of the fuel element, the fuel and moderator elements being oriented so that the fuel elements face each other and the moderator elements do likewise, adjacent moderator elements being spaced to provide air inlet channels, and adjacent fuel elements being spaced to provide air outlet channels which communicate with the interior of the peripheral ducts, and means for introducing air into the air inlet channels which passes through the porous moderator elements and porous fuel elements to the outlet channel.

  3. Coordination of the U.S. DOE-Argentine National Atomic Energy Commission (CNEA) science and technology implementing arrangement. Final report

    SciTech Connect

    Ebadian, M.A.

    1998-01-01

    In 1989, the US Department of Energy (DOE) established the Office of Environmental Management (EM) and delegated to the office the responsibility of cleaning up the US nuclear weapons complex. EM`s mission has three primary activities: (1) to assess, remediate, and monitor contaminated sites and facilities; (2) to store, treat, and dispose of wastes from past and current operations; and (3) to develop and implement innovative technologies for environmental remediation. To this end, EM has established domestic and international cooperative technology development programs, including one with the Republic of Argentina. Cooperating with Argentine scientific institutes and industry meets US cleanup objectives by: (1) identifying and accessing Argentine EM-related technologies, thereby leveraging investments and providing cost-savings; (2) improving access to technical information, scientific expertise, and technologies applicable to EM needs; and (3) fostering the development of innovative environmental technologies by increasing US private sector opportunities in Argentina in EM-related areas. Florida International University`s Hemispheric Center for Environmental Technology (FIU-HCET) serves as DOE-OST`s primary technology transfer agent. FIU-HCET acts as the coordinating and managing body for the Department of Energy (DOE)-Argentina National Atomic Energy Commission (CNEA) Arrangement. Activities include implementing standard operating procedures, tracking various technical projects, hosting visiting scientists, advising DOE of potential joint projects based on previous studies, and demonstrating/transferring desired technology. HCET hosts and directs the annual Joint Coordinating Committee for Radioactive and Mixed Waste Management meeting between the DOE and CNEA representatives. Additionally, HCET is evaluating the possibility of establishing similar arrangements with other Latin American countries.

  4. Successive reactivation of older structures under variable heat flow conditions evidenced by K-Ar fault gouge dating in Sierra de Ambato, northern Argentine broken foreland

    NASA Astrophysics Data System (ADS)

    Nóbile, Julieta C.; Collo, Gilda; Dávila, Federico M.; Martina, Federico; Wemmer, Klaus

    2015-12-01

    The Argentine broken foreland has been the subject of continuous research to determine the uplift and exhumation history of the region. High-elevation mountains are the result of N-S reverse faults that disrupted a W-E Miocene Andean foreland basin. In the Sierra de Ambato (northern Argentine broken foreland) the reverse faults offset Neogene sedimentary rocks (Aconquija Fm., ˜9 Ma) and affect the basement comprising Paleozoic metamorphic rocks that have been dated at ˜477-470 Ma. In order to establish a chronology of these faults affecting the previous continuous basin we date the formation age of clay minerals associated with fault gouge using the K-Ar dating technique. Clay mineral formation is a fundamental process in the evolution of faults under the brittle regime (<<300 °C). K-Ar ages (9 fractions from 3 samples collected along a transect in the Sierra de Ambato) vary from Late Devonian to Late Triassic (˜360-220 Ma). This age distribution can be explained by a long lasting brittle deformation history with a minimum age of ˜360 Ma and a last clay minerals forming event at ˜220 Ma. Moreover, given the progression of apparent ages decreasing from coarse to fine size fractions (˜360-311 Ma for 2-1 μm grain size fraction, ˜326-286 Ma for 1-0.2 μm and ˜291-219 Ma of <0.2 μm), we modeled discrete deformation events at ˜417 Ma (ending of the Famatinian cycle), ˜317-326 Ma (end of Gondwanic orogeny), and ˜194-279 Ma (Early Permian - Jurassic deformation). According to our data, the Neogene reactivation would not have affected the K-Ar system neither generated a significant clay minerals crystallization in the fault gouge, although an exhumation of more than 2 Km is recorded in this period from stratigraphic data.

  5. Hybrid plasmachemical reactor

    SciTech Connect

    Lelevkin, V. M. Smirnova, Yu. G.; Tokarev, A. V.

    2015-04-15

    A hybrid plasmachemical reactor on the basis of a dielectric barrier discharge in a transformer is developed. The characteristics of the reactor as functions of the dielectric barrier discharge parameters are determined.

  6. Attrition reactor system

    SciTech Connect

    Scott, C.D.; Davison, B.H.

    1993-09-28

    A reactor vessel for reacting a solid particulate with a liquid reactant has a centrifugal pump in circulatory flow communication with the reactor vessel for providing particulate attrition, resulting in additional fresh surface where the reaction can occur. 2 figures.

  7. Attrition reactor system

    SciTech Connect

    Scott, Charles D.; Davison, Brian H.

    1993-01-01

    A reactor vessel for reacting a solid particulate with a liquid reactant has a centrifugal pump in circulatory flow communication with the reactor vessel for providing particulate attrition, resulting in additional fresh surface where the reaction can occur.

  8. NEUTRONIC REACTOR POWER PLANT

    DOEpatents

    Metcalf, H.E.

    1962-12-25

    This patent relates to a nuclear reactor power plant incorporating an air-cooled, beryllium oxide-moderated, pebble bed reactor. According to the invention means are provided for circulating a flow of air through tubes in the reactor to a turbine and for directing a sidestream of the circu1ating air through the pebble bed to remove fission products therefrom as well as assist in cooling the reactor. (AEC)

  9. Period meter for reactors

    DOEpatents

    Rusch, Gordon K.

    1976-01-06

    An improved log N amplifier type nuclear reactor period meter with reduced probability for noise-induced scrams is provided. With the reactor at low power levels a sampling circuit is provided to determine the reactor period by measuring the finite change in the amplitude of the log N amplifier output signal for a predetermined time period, while at high power levels, differentiation of the log N amplifier output signal provides an additional measure of the reactor period.

  10. Reactor System Transient Code.

    Energy Science and Technology Software Center (ESTSC)

    1999-07-14

    RELAP3B describes the behavior of water-cooled nuclear reactors during postulated accidents or power transients, such as large reactivity excursions, coolant losses or pump failures. The program calculates flows, mass and energy inventories, pressures, temperatures, and steam qualities along with variables associated with reactor power, reactor heat transfer, or control systems. Its versatility allows one to describe simple hydraulic systems as well as complex reactor systems.

  11. Advanced Test Reactor Tour

    SciTech Connect

    Miley, Don

    2011-01-01

    The Advanced Test Reactor at Idaho National Laboratory is the foremost nuclear materials test reactor in the world. This virtual tour describes the reactor, how experiments are conducted, and how spent nuclear fuel is handled and stored. For more information about INL research, visit http://www.facebook.com/idahonationallaboratory.

  12. Advanced Test Reactor Tour

    ScienceCinema

    Miley, Don

    2013-05-28

    The Advanced Test Reactor at Idaho National Laboratory is the foremost nuclear materials test reactor in the world. This virtual tour describes the reactor, how experiments are conducted, and how spent nuclear fuel is handled and stored. For more information about INL research, visit http://www.facebook.com/idahonationallaboratory.

  13. NEUTRONIC REACTOR SHIELDING

    DOEpatents

    Borst, L.B.

    1961-07-11

    A special hydrogenous concrete shielding for reactors is described. In addition to Portland cement and water, the concrete essentially comprises 30 to 60% by weight barytes aggregate for enhanced attenuation of fast neutrons. The biological shields of AEC's Oak Ridge Graphite Reactor and Materials Testing Reactor are particular embodiments.

  14. Improved vortex reactor system

    DOEpatents

    Diebold, James P.; Scahill, John W.

    1995-01-01

    An improved vortex reactor system for affecting fast pyrolysis of biomass and Refuse Derived Fuel (RDF) feed materials comprising: a vortex reactor having its axis vertically disposed in relation to a jet of a horizontally disposed steam ejector that impels feed materials from a feeder and solids from a recycle loop along with a motive gas into a top part of said reactor.

  15. NUCLEAR REACTOR CONTROL SYSTEM

    DOEpatents

    Epler, E.P.; Hanauer, S.H.; Oakes, L.C.

    1959-11-01

    A control system is described for a nuclear reactor using enriched uranium fuel of the type of the swimming pool and other heterogeneous nuclear reactors. Circuits are included for automatically removing and inserting the control rods during the course of normal operation. Appropriate safety circuits close down the nuclear reactor in the event of emergency.

  16. University Reactor Instrumentation Grant

    SciTech Connect

    S. M. Bajorek

    2000-02-01

    A noble gas air monitoring system was purchased through the University Reactor Instrumentation Grant Program. This monitor was installed in the Kansas State TRIGA reactor bay at a location near the top surface of the reactor pool according to recommendation by the supplier. This system is now functional and has been incorporated into the facility license.

  17. High solids fermentation reactor

    DOEpatents

    Wyman, Charles E.; Grohmann, Karel; Himmel, Michael E.; Richard, Christopher J.

    1993-03-02

    A fermentation reactor and method for fermentation of materials having greater than about 10% solids. The reactor includes a rotatable shaft along the central axis, the shaft including rods extending outwardly to mix the materials. The reactor and method are useful for anaerobic digestion of municipal solid wastes to produce methane, for production of commodity chemicals from organic materials, and for microbial fermentation processes.

  18. High solids fermentation reactor

    DOEpatents

    Wyman, Charles E.; Grohmann, Karel; Himmel, Michael E.; Richard, Christopher J.

    1993-01-01

    A fermentation reactor and method for fermentation of materials having greater than about 10% solids. The reactor includes a rotatable shaft along the central axis, the shaft including rods extending outwardly to mix the materials. The reactor and method are useful for anaerobic digestion of municipal solid wastes to produce methane, for production of commodity chemicals from organic materials, and for microbial fermentation processes.

  19. Neutron behavior, reactor control, and reactor heat transfer. Volume four

    SciTech Connect

    Not Available

    1986-01-01

    Volume four covers neutron behavior (neutron absorption, how big are nuclei, neutron slowing down, neutron losses, the self-sustaining reactor), reactor control (what is controlled in a reactor, controlling neutron population, is it easy to control a reactor, range of reactor control, what happens when the fuel burns up, controlling a PWR, controlling a BWR, inherent safety of reactors), and reactor heat transfer (heat generation in a nuclear reactor, how is heat removed from a reactor core, heat transfer rate, heat transfer properties of the reactor coolant).

  20. Reactor vessel support system

    DOEpatents

    Golden, Martin P.; Holley, John C.

    1982-01-01

    A reactor vessel support system includes a support ring at the reactor top supported through a box ring on a ledge of the reactor containment. The box ring includes an annular space in the center of its cross-section to reduce heat flow and is keyed to the support ledge to transmit seismic forces from the reactor vessel to the containment structure. A coolant channel is provided at the outside circumference of the support ring to supply coolant gas through the keyways to channels between the reactor vessel and support ledge into the containment space.

  1. Nuclear reactor overflow line

    DOEpatents

    Severson, Wayne J.

    1976-01-01

    The overflow line for the reactor vessel of a liquid-metal-cooled nuclear reactor includes means for establishing and maintaining a continuous bleed flow of coolant amounting to 5 to 10% of the total coolant flow through the overflow line to prevent thermal shock to the overflow line when the reactor is restarted following a trip. Preferably a tube is disposed concentrically just inside the overflow line extending from a point just inside the reactor vessel to an overflow tank and a suction line is provided opening into the body of liquid metal in the reactor vessel and into the annulus between the overflow line and the inner tube.

  2. Reactor water cleanup system

    DOEpatents

    Gluntz, Douglas M.; Taft, William E.

    1994-01-01

    A reactor water cleanup system includes a reactor pressure vessel containing a reactor core submerged in reactor water. First and second parallel cleanup trains are provided for extracting portions of the reactor water from the pressure vessel, cleaning the extracted water, and returning the cleaned water to the pressure vessel. Each of the cleanup trains includes a heat exchanger for cooling the reactor water, and a cleaner for cleaning the cooled reactor water. A return line is disposed between the cleaner and the pressure vessel for channeling the cleaned water thereto in a first mode of operation. A portion of the cooled water is bypassed around the cleaner during a second mode of operation and returned through the pressure vessel for shutdown cooling.

  3. Reactor water cleanup system

    DOEpatents

    Gluntz, D.M.; Taft, W.E.

    1994-12-20

    A reactor water cleanup system includes a reactor pressure vessel containing a reactor core submerged in reactor water. First and second parallel cleanup trains are provided for extracting portions of the reactor water from the pressure vessel, cleaning the extracted water, and returning the cleaned water to the pressure vessel. Each of the cleanup trains includes a heat exchanger for cooling the reactor water, and a cleaner for cleaning the cooled reactor water. A return line is disposed between the cleaner and the pressure vessel for channeling the cleaned water thereto in a first mode of operation. A portion of the cooled water is bypassed around the cleaner during a second mode of operation and returned through the pressure vessel for shutdown cooling. 1 figure.

  4. Spinning fluids reactor

    DOEpatents

    Miller, Jan D; Hupka, Jan; Aranowski, Robert

    2012-11-20

    A spinning fluids reactor, includes a reactor body (24) having a circular cross-section and a fluid contactor screen (26) within the reactor body (24). The fluid contactor screen (26) having a plurality of apertures and a circular cross-section concentric with the reactor body (24) for a length thus forming an inner volume (28) bound by the fluid contactor screen (26) and an outer volume (30) bound by the reactor body (24) and the fluid contactor screen (26). A primary inlet (20) can be operatively connected to the reactor body (24) and can be configured to produce flow-through first spinning flow of a first fluid within the inner volume (28). A secondary inlet (22) can similarly be operatively connected to the reactor body (24) and can be configured to produce a second flow of a second fluid within the outer volume (30) which is optionally spinning.

  5. Discussion about decision support systems using continuous multi-criteria methods for planning in areas with hydro-basins, agriculture and forests, from examples in Argentine.

    NASA Astrophysics Data System (ADS)

    Anton, J. M.; Grau, J. B.; Tarquis, A. M.; Andina, D.; Cisneros, J. M.; Sanchez, E.

    2012-04-01

    The authors were involved last years in projects considering diverse decision problems on the use of some regions in Argentine, and also related to rivers or rural services in them. They used sets of multi-criteria decision methods, first discrete when the problem included few distinct alternatives, such as e.g. forestry, traditional or intensive agriculture. For attributes they were different effects, classified then in environmental, economic and social criteria. Extending to other gentler areas, such as at South of the Province of Córdoba, Arg., they have balanced more delicately effects of continuous levels of actions, with a combination of Goal Programming linked methods, and they adopted compromises to have precise solutions. That has shown, and in part open, a line of research, as the setting of such models require various kinds of definitions and valuations, including optimizations, goals with penalties in deviations and restrictions. That can be in diverse detail level and horizon, in presence of various technical and human horizons, and that can influence politics of use of terrain and production that will require public and private agents. The research will consider consideration of use and conservation of soils, human systems and agro productions, and hence models for optimization, preferably in such Goal Programming ways. That will require considering various systems of models, first in theory to be reliable, and then in different areas to evaluate the quality of conclusions, and maybe that successively if results are found advantageous. The Bayesian ways will be considered, but they would require a prospective of sets of precise future states of nature or markets with elicited probabilities, which are neither evident nor decisive for the moment, as changes may occur in years but will be very unexpected or uncertain. The results will be lines of models to aid to establish policies of use of territories, by public agencies setting frames for private

  6. Hybrid reactors. [Fuel cycle

    SciTech Connect

    Moir, R.W.

    1980-09-09

    The rationale for hybrid fusion-fission reactors is the production of fissile fuel for fission reactors. A new class of reactor, the fission-suppressed hybrid promises unusually good safety features as well as the ability to support 25 light-water reactors of the same nuclear power rating, or even more high-conversion-ratio reactors such as the heavy-water type. One 4000-MW nuclear hybrid can produce 7200 kg of /sup 233/U per year. To obtain good economics, injector efficiency times plasma gain (eta/sub i/Q) should be greater than 2, the wall load should be greater than 1 MW.m/sup -2/, and the hybrid should cost less than 6 times the cost of a light-water reactor. Introduction rates for the fission-suppressed hybrid are usually rapid.

  7. HORIZONTAL BOILING REACTOR SYSTEM

    DOEpatents

    Treshow, M.

    1958-11-18

    Reactors of the boiling water type are described wherein water serves both as the moderator and coolant. The reactor system consists essentially of a horizontal pressure vessel divided into two compartments by a weir, a thermal neutronic reactor core having vertical coolant passages and designed to use water as a moderator-coolant posltioned in one compartment, means for removing live steam from the other compartment and means for conveying feed-water and water from the steam compartment to the reactor compartment. The system further includes auxiliary apparatus to utilize the steam for driving a turbine and returning the condensate to the feed-water inlet of the reactor. The entire system is designed so that the reactor is self-regulating and has self-limiting power and self-limiting pressure features.

  8. NEUTRONIC REACTOR CONTROL

    DOEpatents

    Dreffin, R.S.

    1959-12-15

    A control means for a nuclear reactor is described. Particularly a device extending into the active portion of the reactor consisting of two hollow elements coaxially disposed and forming a channel therebetween, the cross sectional area of the channel increasing from each extremity of the device towards the center thereof. An element of neutron absorbing material is slidably positionable within the inner hollow element and a fluid reactor poison is introduced into the channel defined by the two hollow elements.

  9. Improved vortex reactor system

    DOEpatents

    Diebold, J.P.; Scahill, J.W.

    1995-05-09

    An improved vortex reactor system is described for affecting fast pyrolysis of biomass and Refuse Derived Fuel (RDF) feed materials comprising: a vortex reactor having its axis vertically disposed in relation to a jet of a horizontally disposed steam ejector that impels feed materials from a feeder and solids from a recycle loop along with a motive gas into a top part of said reactor. 12 figs.

  10. FLOW SYSTEM FOR REACTOR

    DOEpatents

    Zinn, W.H.

    1963-06-11

    A reactor is designed with means for terminating the reaction when returning coolant is below a predetermined temperature. Coolant flowing from the reactor passes through a heat exchanger to a lower reservoir, and then circulates between the lower reservoir and an upper reservoir before being returned to the reactor. Means responsive to the temperature of the coolant in the return conduit terminate the chain reaction when the temperature reaches a predetermined minimum value. (AEC)