Sample records for emplear iones plata
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Energy Technology Data Exchange (ETDEWEB)
Silva, Susana M; Martinez Meza, Esteban; Alvarez Gallegos, Alberto [Instituto de Investigaciones Electricas, Temixco, Morelos (Mexico)
2001-07-01
sistema continuo el pH se mantuvo en el intervalo de pH de 7 a 8 mediante la adicion de acido sulfurico y se conservo un delta de temperatura de 10 (27 {+-} 5 ). El pH, la conductividad y la temperatura se midieron en forma continua. Se muestran graficas de efecto de iones plata/cobre sobre el aniquilamiento de bacterias coliformes totales y coliformes fecales se da como figura el efecto de la concentracion del ion metalico plata sobre el aniquilamiento de bacterias relacionadas con fierro. Se puede concluir que los sistemas de planta, plata/cobre y cobre estudiados resultaron ser una buena alternativa con un minimo impacto ambiental para sustituir el cloro en los sistemas de enfriamiento. Estos sistemas lograron abatir a las poblaciones bacterianas promotoras de la corrrosion influenciada microbiologicamente y del ensuciamiento biologico a niveles de 1000 ufc/mL y menores compitiendo con los tratamientos de aguas de enfriamiento convencionales. (abstract truncated)
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Visits to La Plata Observatory
Feinstein, A.
1985-03-01
La Plata Observatory will welcome visitors to ESO-La Silla that are willing to make a stop at Buenos Aires on their trip to Chile or on their way back. There is a nice guesthouse at the Observatory that can be used, for a couple of days or so, by astronomers interested in visiting the Observatory and delivering talks on their research work to the Argentine colleagues. No payments can, however, be made at present. La Plata is at 60 km from Buenos Aires. In the same area lie the Instituto de Astronomia y Fisica dei Espacio (IAFE), in Buenos Aires proper, and the Instituto Argentino de Radioastronomia (IAR). about 40 km from Buenos Aires on the way to La Plata. Those interested should contacl: Sr Decano Prof. Cesar A. Mondinalli, or Dr Alejandro Feinstein, Observatorio Astron6mico, Paseo dei Bosque, 1900 La Plata, Argentina. Telex: 31216 CESLA AR.
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Síntesis y Caracterización de Ag2Cu2O3, el primer óxido de cobre y plata
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Gómez-Romero, P.
2000-06-01
Full Text Available Despite the crystal-chemical similarities between copper and silver ions, there is no known silver copper oxide, neither natural nor synthetic. In this work, we present the synthesis at room-temperature of the first silver copper oxide of formula Ag2Cu2O3 (tetragonal, a=5.8857(3Å, c=10.6868(7Å, space group I41/amd, Z=4. It should be noted that the thermal stability of this new oxide is enhanced with respect to Ag2O or even CuO. The structure consists of alternating chains of edge-sharing square planar Cu(II and zigzag chains of linearly coordinated Ag(I ions.A pesar de las similitudes cristaloquímicas entre los iones de cobre y los de plata, no existe ningún óxido mixto de cobre y plata ni natural ni sintético. En este trabajo se presenta la síntesis a bajas temperaturas del primer óxido mixto de cobre y plata, de fórmula Ag2Cu2O3 (tetragonal, a=5.8857(3Å, c=10.6868(7Å, grupo espacial I41/amd, Z=4. Este óxido posee una estabilidad térmica superior a los correspondientes óxidos de cobre y de plata. Contiene cadenas de iones Cu(II cuadrado-planos que alternan con cadenas en zig-zag de Ag(I con coordinación lineal.
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Alejandro David, Agama Mosquera; Peña Estrella, Julián
2013-01-01
En este proyecto se logró construir en el laboratorio de materiales un electrodo experimental plata/cloruro de plata para medición de potenciales eléctricos en estructuras sumergidas. Utilizando un procedimiento experimental llamado electrolisis se formo sobre el electrodo, específicamente en la rejilla del electrodo experimental una capa fina de cloruro de plata. A continuación se realizó los cálculos pertinentes de la masa de cloruro de plata que se formo durante el proceso de electrolisis ...
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Occurrence of Microcystis aeruginosa and microcystins in Río de la Plata river (Argentina
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Darío Andrinolo
2007-07-01
Full Text Available This paper is the first report on microcystins producer blooms of Microcystis aeruginosa in the Argentinean coast of the Río de la Plata river, the most important drinking water supply of Argentina. The distribution of toxic cyanobacterium Microcystis cf. aeruginosa blooms in the Argentinean coast of the Rio de la Plata river was studied from December 2003 and January 2006. Microcystis aeruginosa persisted in the river with values ranged between 0 - 7.8 10(4 cells ml-1. Samples of two Microcystis aeruginosa water blooms were collected at La Plata river and were analyzed by the mouse bioassay and by high-performance liquid chromatography with Diode-array and MS detector. The samples showed high hepatotoxicity in mouse bioassay and, in accordance, important amount of microcystins. The bloom samples contained microcystins LR and a variant of microcystin with a molecular ion [M+H]+= 1037.8 m/z as major components. The total toxin content found in these samples was 0.94μg/mg and 0.69μg/mg of lyophilised cells. We conclude that the presence of toxic clones of Microcystis aeruginosa in the Argentinean coast of the Río de la Plata is an actual sanitary and environmental problem and that further studies are necessary to make the risk assessment.
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Energy Technology Data Exchange (ETDEWEB)
Santucci, L., E-mail: eleocarol@fcnym.unlp.edu.ar [Centro de Investigaciones Geológicas (CIG), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad Nacional de La Plata - UNLP, Calle 64 y Diag. 113, 1900 La Plata, Buenos Aires (Argentina); Carol, E. [Centro de Investigaciones Geológicas (CIG), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad Nacional de La Plata - UNLP, Calle 64 y Diag. 113, 1900 La Plata, Buenos Aires (Argentina); Kruse, E. [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Cátedra de Hidrología General de la Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata (UNLP), Calle 64 #3, 1900 La Plata, Buenos Aires (Argentina)
2016-10-01
The hydrochemistry of minor elements and traces such as bromide, lithium, strontium, uranium and selenium, together with the chemical analysis of major ions, has been used in the study of salinization process. This process occurs in a semi-confined aquifer that corresponds to a Pliocene–Pleistocene fluvial environment. The semi-confined aquifer is located in the littoral of the cities of Ensenada and Berisso, in the region of the middle Río de la Plata estuary, Argentina. Groundwater salinization was detected in the semi-confined aquifer in the coastal plain area, with salt contents that increase from the loess plain towards the river. The content of major ions that predominate in sea water (Cl{sup −}, Na{sup +} and Mg{sup 2+}), as well as the Cl{sup −}/Br{sup −} and U vs. Cl{sup −} ratios, demonstrates that such salinization is related to sea water, which shows no correspondence with estuary water. In the salinized area, Li, Sr and Se enrichments occur, and are used as tracers of the average time that a substance remains in solution in sea water in the aquifer. The study of such minor ions together with the geological evolution of the area made it possible to recognize that the salt water in the semi-confined aquifer corresponds to a palaeo-intrusion of sea water associated with the Pleistocene–Holocene ingressions caused by the climate changes occurring during the Quaternary. - Highlights: • The semi-confined aquifer in a sector of the Río de la Plata estuary is salinized. • Saline content is higher in the aquifer than in the estuary. • Minor elements indicate the occurrence of palaeo-seawater intrusion. • Palaeo-seawater intrusion may be associated with interglacial fluctuations.
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International Nuclear Information System (INIS)
Santucci, L.; Carol, E.; Kruse, E.
2016-01-01
The hydrochemistry of minor elements and traces such as bromide, lithium, strontium, uranium and selenium, together with the chemical analysis of major ions, has been used in the study of salinization process. This process occurs in a semi-confined aquifer that corresponds to a Pliocene–Pleistocene fluvial environment. The semi-confined aquifer is located in the littoral of the cities of Ensenada and Berisso, in the region of the middle Río de la Plata estuary, Argentina. Groundwater salinization was detected in the semi-confined aquifer in the coastal plain area, with salt contents that increase from the loess plain towards the river. The content of major ions that predominate in sea water (Cl"−, Na"+ and Mg"2"+), as well as the Cl"−/Br"− and U vs. Cl"− ratios, demonstrates that such salinization is related to sea water, which shows no correspondence with estuary water. In the salinized area, Li, Sr and Se enrichments occur, and are used as tracers of the average time that a substance remains in solution in sea water in the aquifer. The study of such minor ions together with the geological evolution of the area made it possible to recognize that the salt water in the semi-confined aquifer corresponds to a palaeo-intrusion of sea water associated with the Pleistocene–Holocene ingressions caused by the climate changes occurring during the Quaternary. - Highlights: • The semi-confined aquifer in a sector of the Río de la Plata estuary is salinized. • Saline content is higher in the aquifer than in the estuary. • Minor elements indicate the occurrence of palaeo-seawater intrusion. • Palaeo-seawater intrusion may be associated with interglacial fluctuations.
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Generación controlada de nanocoloides de plata en materiales silíceos amorfos
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Gil, C.
2004-04-01
Full Text Available Amorphous silica-based materials bulk and superficially doped with silver nanocolloids were prepared. Bulk doped glasses were obtained by conventional melting and doped monolithic slabs by sol-gel. Superficially doped glasses were obtained by ion-exchange and doped coatings by sol-gel. The samples were characterised by TEM and UV-VIS spectrophotometry. Depending on the composition, the silver incorporation process, and the thermal treatments, several colourings were obtained. By controlling these parameters, metallic silver nanocolloids can be generated in the matrices studied. Colloids aggregation and growing up depends on the matrix nature and on the experimental process carried out.
Se prepararon materiales silíceos amorfos dopados con nanocoloides de plata en masa y en superficie. Se obtuvieron vidrios dopados en masa por fusión convencional y láminas monolíticas dopadas por sol-gel. Asimismo se prepararon vidrios dopados superficialmente por cambio iónico y recubrimientos dopados por sol-gel. Los materiales se caracterizaron por MET y espectrofotometría UV-VIS. Dependiendo de la composición del material, del proceso de incorporación de la plata y de los tratamientos térmicos, se obtuvieron diferentes coloraciones. El control de estas variables permitió generar nanocoloides metálicos de plata en las matrices estudiadas. La agregación y crecimiento de los coloides depende de la naturaleza de la matriz y del proceso experimental utilizado. -
Teaching Humanities at the National University of la Plata, Argentina.
Acuña, Leopoldo E
2003-10-01
In this article the author begins by giving a brief history of medical education in Argentina, then provides some background information on the National University of La Plata. He describes two major initiatives at La Plata: a new and pioneering admission policy (implemented in 1993) and a change in the number of hours and years in the curriculum. He then looks back to the introduction in 1976 of La Plata's medical humanities program. Over its 20 year existence, the program has undergone a number of changes in response both to students' interests and financial concerns. The revised humanities curriculum now consists of four elective courses: medicine and literature, anthropology, history of medicine, and "medical kalology" (which focuses on music and dance). Unfortunately, the program, while it has been well received by both students and faculty and has inspired programs at other Argentinean schools, is threatened by Argentina's economic crisis.
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Sedimentation Survey of Lago La Plata, Puerto Rico, July 2006
Soler-López, Luis R.
2008-01-01
Lago La Plata dam is located between the municipalities of Naranjito and Toa Alta in north central Puerto Rico, about 5 kilometers south of the town of Toa Alta and about 5 kilometers north of the town of Naranjito. The reservoir impounds the waters of the Rio de La Plata, the Rio Guadiana, and the Rio Ca?as, and is part of the San Juan Metropolitan Water District, which provides about 35 percent of the total water demand for the area (Soler-Lopez and others, 2000). The reservoir has a drainage area of about 469 square kilometers. The dam was constructed in 1974 and is a concrete gravity structure with a normal pool elevation of 52.00 meters above mean sea level (Puerto Rico Electric Power Authority, 1979). During October 1998, the U.S. Geological Survey (USGS), Caribbean Water Science Center, in cooperation with the Puerto Rico Aqueduct and Sewer Authority (PRASA) conducted a bathymetric survey of Lago La Plata to assess the impact of Hurricane Georges on the storage capacity of the reservoir. Between July 17 and 20, 2006, the USGS and the PRASA conducted an additional bathymetric survey of Lago La Plata to update the reservoir storage capacity and determine the reservoir sedimentation rate by comparing the 2006 survey data with the 1998 survey data.. The purpose of this report is to update the reservoir storage capacity, sedimentation rates, and areas of substantial sediment accumulation since 1998. Historical (1974) data are referenced as needed to account for long-term storage capacity loss trends...
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Energy Technology Data Exchange (ETDEWEB)
Guichon, B. A. [Universidad Nacional de La Plata, Instituto de Geomorfologia y Suelos (Argentina); Desimoni, J.; Mercader, R. C., E-mail: mercader@fisica.unlp.edu.ar [Universidad Nacional de La Plata, Departamento de Fisica, IFLP-CONICET, Facultad de Ciencias Exactas (Argentina); Imbellone, P. A. [Universidad Nacional de La Plata, Instituto de Geomorfologia y Suelos (Argentina)
2010-01-15
In the present work, we have applied Moessbauer spectroscopy as well as the traditional chemical analyses to assess the contents of different states of Fe in oxides and hydroxides in an Entisol soil from the Argentine coastal plain of the Rio de La Plata. Tentative assignments for the different Fe ion sites are proposed. Our findings show that the isomer shift and quadrupole splitting are sensitive to the changes detected in the Fe{sup 2+} contents of the soluble phase while others remain constant within the experimental uncertainties.
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Directory of Open Access Journals (Sweden)
Diego E. Gutiérrez-Gregoric
2010-08-01
Full Text Available Melanoides tuberculatus es un gasterópodo cosmopolita que ha invadido y se ha establecido en casi todos los países del continente americano, desconociéndose en la mayoría de los casos el origen de su introducción. En este trabajo se menciona el riesgo de establecimiento de esta especie en áreas de influencia del Río de la Plata como consecuencia de su registro en acuarios de la ciudad de La Plata (Buenos Aires, Argentina dedicados a la venta de flora y fauna limnética. A principios de 2009, la especie fue identificada a partir de 26 ejemplares procedentes de un comercio, siendo éste el registro más austral de la especie para una localidad de la cuenca del Plata. Revisiones posteriores en 3 locales comerciales de la ciudad confirmaron la presencia de la especie en 2 de ellos. Dicha presencia se relacionó con la adquisición de plantas ornamentales por parte de los establecimientos. La identificación del gasterópodo en la ciudad de La Plata debe considerarse cuidadosamente, debido a las posibles consecuencias que tendría la liberación accidental de este molusco en el Río de la Plata en lo relacionado con el desplazamiento de fauna local y salud pública.Melanoides tuberculatus is a cosmopolitan gastropod that has invaded and has now spread into most countries of the American continent. Introduction pathways remain unknown in most cases. This work draws attention on the colonization risks of this species in the Río de la Plata area as a consequence of its record in flower and pet shops - in the city of La Plata (Buenos Aires, Argentina - in which limnic species are sold. The species was identified at the beginning of 2009 within a lot of 29 specimens from a shop, and this is the southernmost record of this species in the Plata Basin. Subsequent surveys in 3 commercial shops in the same city revealed its presence in 2 of them. This was related to the purchase of ornamental plants by the shops. Identification of this species in the
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The Hydrologic Regime of the La Plata Basin in South America
Berbery, E. H.; Barros, V. R.
2002-12-01
The main components of the hydrologic cycle of the La Plata basin in southeastern South America are investigated using a combination of observations, satellite products and National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) global reanalyses. La Plata basin is second only to the Amazon basin in South America, and plays a critical role in the economies of the region. It is a primary factor in energy production, water resources, transportation, agriculture and livestock. Of particular interest was to evaluate the annual cycle of the hydrologic cycle components. The La Plata annual-mean river discharge is about 21,000 m3 s-1, and the amplitude of the mean annual cycle of La Plata River discharge is small: it is slightly larger during late summer, but continues with large volumes even during winter. The reason is that different precipitation regimes over different locations contribute to the total river discharge. One regime is found toward the northern boundary, where precipitation peaks during summer in association with the southernmost extension of the monsoon system. A second one is found over the central part of the basin, where precipitation peaks at different times in the seasonal cycle. Further analysis of the main tributaries of La Plata (Paran , Uruguay and Paraguay) reveals that each has a well defined annual cycle, but with different phases that can be traced primarily to each basin's physiography and precipitation regime. The upper and middle portions of the Paran River are most influenced by the summer monsoon regime, thus the river has a maximum discharge in late summer. The annual cycle of precipitation over the Uruguay River basin has two maxima, one in late autumn and the second one in spring and, consistently, the river discharge is largest in winter and spring. The smooth annual cycle of the Paraguay River discharge, with a maximum in winter, is the result of the Pantanal, a large wetland that
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A Numerical Study of the Plata River Plume Along the Southeastern South American Continental Shelf
2005-01-01
the effect of ambient shelf currents, level decreased by -0.20 and -0.55 in at the estuary and which would be essential in the determination of the 142...Res. SI 39, realistic wind and tidal forcing. J. Geophys. Res., 101 (submitted). (C2):3435-3455. Piola, A. R. 2002. El impacto del Plata sobre la...discharge on the continental impactos en el Plata y en la regi6n pampeana. Vol. 1. shelf. 1. Modeling the river plume and the inner shelf Assoc. Bonaerense de
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The International Summer School on Land Cover Change and Hydroclimate of the La Plata Basin
Berbery, Ernesto Hugo; Herdies, Dirceu L.; Alcaraz-Segura, Domingo; de Goncalves, Luis G. G.; Lettenmaier, Dennis P.; Toll, David
2011-01-01
The La Plata Basin (LPB) in southern South America has been subject to land cover and land use changes (LCLUCs) since colonial times and with an accelerated rate in the last decades and over extensive areas. The work of Ameghino even suggested that there were relations between those land use changes and the frequency of droughts and floods in the region. Despite this early knowledge, not much is known of the potential impacts of LCLUC on the hydroclimate of the La Plata basin. Besides, over the last century much of the La Plata Basin has had a reported increase in precipitation and heavy rains, and these changes along with an increase in population growth - have resulted in more adverse effects from flooding. To draw attention to these issues, during two weeks in November 2009 the International Summer School on Land Cover Change and Hydroclimate of the La Plata Basin was organized at the grounds of the Itaip Hydropower Plant in Brazil. The school was the result of the combination of interests between the La Plata Basin Regional Hydroclimate Project, the Inter-American Institute for Global Change Research (IAI), and the International Hydroinformatics Center (IHC) in Itaip . LPB is an umbrella project endorsed by the Global Energy and Water Cycle Experiment (GEWEX) and the Climate Prediction and Variability (CLIVAR), both of the World Climate Research Programme (WCRP). LPB has made a priority to train young scientists and promote interdisciplinary collaborations in areas related to Climate, Hydrology, Ecology and Agriculture. The IAI, with a similar agenda, was a natural partner to develop this Summer School, which in turn benefited from Itaipu s interest in relating with the scientific community of neighboring countries. The choice of location (Itaip Technological Park) was made so that participants could relate research usually done at academic institutions to applications and operations at one of the largest hydropower plants in the world. The school was attended
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Tostación de un concentrado refractario de oro y plata
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Coronado, J. H.
2012-06-01
Full Text Available In processing of precious metal ores with high pyrite content, refractory concentrates are obtained, which are difficult to process. A refractory gold and silver concentrate was leached with sodium cyanide. Results show low extraction percentages, being 34 % of gold and 40 % of silver. A roasting method to oxidize the concentrate was used, making it more susceptible to cyanidation, hence a more efficient way to extract precious metals. The variables include roasting temperature and roasting and cyanidation time. In addition, the hot calcine was added to the leaching solution at room temperature to analyze the effect on particle size and recovery. The best results, although not entirely satisfactory (50 % of gold and 61 % of silver were obtained by roasting the concentrate for 4 h at 600 °C, followed by cyanidation for 20 h. The lime consumption to raise the pH to about 11.3 was increased markedly to 25 kg/m3.
En el procesamiento de minerales de metales preciosos con altos contenidos de pirita, se obtienen concentrados refractarios difíciles de procesar. En este estudio se lixivió un concentrado refractario de oro y plata con cianuro de sodio, obteniéndose extracciones de 34 % para oro y 40 % para plata. Se utilizó el método de tostación para oxidar el concentrado, haciéndolo más susceptible a la cianuración, y extraer más eficientemente el oro y la plata. Las variables analizadas fueron: temperatura de tostación y tiempos de tostación y cianuración. Además, la calcina caliente se agregó a la solución lixiviante a temperatura ambiente para analizar el efecto en el tamaño de partícula y recuperación. Los mejores resultados, aunque no del todo satisfactorios (50 % oro y 61 % plata, se obtuvieron mediante tostación del concentrado durante 4 h a temperaturas de 600 °C, seguido de una cianuración de 20 h. El consumo de cal para elevar el pH a 11,3, se incrementó notablemente hasta 25 kg/m3. -
Síntesis de nanopartículas de plata por ablación láser funcionalizadas con bicapa de grafeno
Damián Briones, María Angelica; Damián Briones, María Angelica; Damián Briones, María Angelica
2015-01-01
En este trabajo se obtuvo nanopartículas de plata por ablación laser para luego ser funcionalizadas con bicapa de grafeno, mediante la técnica de evaporación. Para la obtención de las nanopartículas de plata se usó un “target” de plata al 99,9% de pureza el cual fue colocado dentro de un recipiente que contenía agua ultrapura, sobre él se incidió un láser de Nd:AYG modelo Brillant, en el cual se pudo controlar la fluencia, longitud de onda, el medio y el tiempo de ablación. Para la obte...
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Evaluation of sand reserves in del Plata City
International Nuclear Information System (INIS)
Loureiro, J.
2014-01-01
The purpose of this study is to evaluate the reserve of sand in the zone of del Plata city and beyond. This area is located in the S E edge of the department of San Jose near the mouth of Santa Lucia river. In this zone was identified the mantle of potentially exploitable sand which are based on their particle size, composition and depth of the limits cape. There are two powerful capes of sand separated by clay and silt
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More than two decades after the introduction of Limnoperna fortunei (Dunker 1857 in La Plata Basin
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M. A. Pessotto
2018-01-01
Full Text Available Abstract The golden mussel, Limnoperna fortunei, is an Asian freshwater bivalve introduced in South America in the beginning of the 1990’s, probably through ballast water releases in La Plata River estuary. It dispersed north through Paraná, Uruguay and Paraguay Rivers. The study evaluated the macroscale (18° to 34° S; 45° to 60° W distribution of L. fortunei (larval stages in the main rivers and reservoirs of La Plata Basin. Samplings were performed through 68 µm vertical plankton net hauls. Limnological variables were simultaneously determined. Larvae abundance correlated significantly with oxygen (positively in summer, with temperature (positively in winter and with total phosphorus and total nitrogen (both negatively in winter. We expected densities to decrease towards north (latitudinal gradient and increase in lentic conditions (reservoirs. Despite maximum density was found near the introduction point (La Plata River similar value was also observed 2,000 km north (Paraguay River. The first hypothesis was refuted. The second hypothesis was partially accepted. Abundances were consistently higher in summer. Higher trophic conditions and fast flow seem to inhibit population growth. Food resources (chlorophyll a locally influenced temporal variation. Limnoperna fortunei is widely distributed in La Plata basin, reaching high larval densities superior to 10,000 ind. m-3, in all major sub-basins. The species exhibits a high intrinsic dispersal ability (free planktonic larvae, wide tolerance to environmental factors and dispersion is potentialized by natural dispersion processes (e.g. fauna displacement and human facilitation (e.g. commercial navigation.
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Una herramienta cartográfica digital basada en XML para la ciudad de La Plata
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Nadia Kreimer
2010-06-01
Full Text Available El trabajo presenta una aplicación específica desarrollada a partir la integración de dos herramientas informáticas: Google Maps y un lenguaje de programación de alto nivel, en nuestro caso Octave. La API de Google Maps en Javascript permite la construcción de objetos espaciales. Integrando el mismo con algoritmos originales que resuelvan la geocodificación de las calles de La Plata y el manejo de una base de datos es posible brindar un servicio de localización. El ejemplo que se presenta es el de la localización de las farmacias más cercanas a un cierto domicilio. Se le pide a los usuarios que ingresen su dirección; con estos datos le son devueltas las tres farmacias de turno más cercanas. El código resulta fácilmente adaptable a otro tipo de requerimientos: estaciones de servicio, restaurantes, etcétera siendo su única limitación que la geocodificación está desarrollada para la ciudad de La Plata.This paper presents a specific application developed by the integration of two tools: Google Maps and a high level programming language: Octave. The Google Maps API in Javascript allows the construction of space objects. This language integrated with algorithms that solve the original geocoding of the streets of La Plata and management of a database can provide a service location. The example presented is the location of the nearest pharmacies to a certain address. Users are prompted to enter their address and the system returns the three closest pharmacies.The code is easily adaptable to other types of requirements: gas stations, restaurants, etc.; its only limitation is that the geocoding is developed for the city of La Plata.
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Directory of Open Access Journals (Sweden)
Perla Imbellone
2011-12-01
Full Text Available Los suelos predominantes en la Planicie costera del río de La Plata, provincia de Buenos Aires, son Vertisoles hidromórficos. Se estudian cuatro suelos representativos en los partidos de La Plata, Ensenada y Berazategui. Se describen y analizan detalladamente las propiedades pedológicas y sedimentológicas. El objeto de esta contribución es analizar: a- la granulometría y mineralogía de los Vertisoles hidro-mórficos de la Llanura de fango del río de la Plata; b- su influencia en la generación de los rasgos morfológicos y c- los procesos de pedogénesis asociados. La morfología de los suelos muestra rasgos de vertisolización e hidromorfismo principalmente en los horizontes superiores y medios de los suelos. Son abundantes los agregados cuneiformes y angulares moderados y fuertes en el solum, con superficies de deslizamiento interpedales, a veces estriadas, visibles en distintos niveles de observación. La matriz puede ser moderadamente o marcadamente anisotrópica y muestra zonas de anisotropismo óptico que atraviesan el material fino con patrones variados o aureolas anisotrópicas alrededor de los poros y granos. La hidromorfia es marcada, con anegamientos frecuentes de origen pluvial; la capa freática está a profundidad general entre 0,80 y 1,20 m, por lo que estarían en condiciones de episaturación y endosaturación en distintos momentos del año. Poseen variedad de rasgos redoximórficos, principalmente matrices reducidas (matices de 2,5Y y 5Y e intensidades de 2 o menores, concentraciones redox de hierro y manganeso y pátinas oscuras. La clase textural es arcillosa, con amplio predominio de la arcilla fina sobre la gruesa. Son Vertisoles illíticos, con muy elevado contenido de arcilla total que genera rasgos vérticos. La influencia hidromórfica se manifiesta por la abundancia y color de las pátinas que están relacionadas con el grado de hidromorfía dentro de cada perfil y las propiedades asociadas al proceso
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Directory of Open Access Journals (Sweden)
Julia Vergara
Full Text Available Pimelodus albicans Valenciennes, 1840 (common name "moncholo" or "bagre blanco" is an endemic species of the family Pimelodidae in the río de la Plata basin. Phylogenetic approach based on cytochrome b sequences was performed to test the existence of a unique evolutionary lineage in P. albicans and to discriminate populations units or subpopulations related to a migration behavior of this taxon in the río de la Plata basin. This study included 34 samples of P. albicans of different collecting sites in the río de la Plata estuary and in the río Arrecifes belonging to the río Paraná basin. Among 614 base pairs in the cytochrome b sequence data set, 203 were variable and 120 were phylogenetically informative sites in P. albicans. A total of twenty haplotypes, nucleotide diversity (p = 0.032 and haplotype diversity = 0.941 were found. Tajima's test showed significant value D= -1.88 (p<0.05 rejecting the neutral mutation hypothesis for the P. albicans data set. All phylogenetic approaches showed that P. albicans included four monophyletic assemblages that were supported by high bootstrap and Bayesian posterior probability values. Minimum spanning network corroborated these groups for P. albicans haplotypes. High genetic structure was found in P. albicans by means of AMOVA analysis showing that the río Arrecifes samples constitute an isolated lineage. Moreover, the high value of genetic divergence (10% between the río de la Plata and the río Arrecifes populations could suggest that P. albicans may be conformed by a sibling species complex. On the other hand, a degree of genetic structuring was detected among different sites of the río de la Plata. A partial isolation of the 760 site may suggest that P. albicans could migrates to different tributaries for reproduction, generating different schools of haplotypes which could mix in the río de la Plata estuary. The high nucleotide diversity found in the 765 site and the existence of gene flow
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Directory of Open Access Journals (Sweden)
Rossana Cacivio
2012-01-01
Full Text Available This article is focused on analytical thinking of the participants of a entrepreneurial development programme in the peri-urban rural region focus in the city of La Plata. The programme it started with an action of the extension of the Universidad Nacional de la Plata [Olmos Emprende], the development led to the joint and more programs national and provincial. The first objective is to describe the conditions in the entrepreneurship in Latin America and contextualize the experience presented. Afterwards a consideration of the local territorial context that would have facilitated the participation in the program, taking into account two regional areas: On the one hand the periurban rural region in general and on the other hand, a series of local dimensions that, in addition to factors techno-economic state and regulatory frameworks, include social and cultural circumstances. The question that crosses the text, focuses on the location of the entrepreneurship in the territory, focusing on their possibilities of local development. We observed the situations of interface between various regional actors, between groups of citizens, various state agencies and the diverse participation also of private agentsEl artículo se centra en la reflexión analítica de los participantes de un programa de desarrollo emprendedor en la Región Rural Periurbana centrada en el municipio de La Plata. El programa partió de una acción de extensión de la Universidad Nacional de La Plata [Olmos Emprende], cuyo desarrollo derivó en la articulación con programas más abarcativos de orden nacional y provincial. El primer objetivo es describir las condiciones específicas en las que se desarrolla la empresarialidad en América Latina y contextualizar la experiencia presentada. Posteriormente se hace una consideración del contexto territorial local que habría facilitado la participación en el programa teniendo en cuenta dos ámbitos regionales: por un lado la Regi
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Mattingly, Kyle S.; Mote, Thomas L.
2017-01-01
Warm-season precipitation variability over subtropical South America is characterized by an inverse relationship between the South Atlantic convergence zone (SACZ) and precipitation over the central and western La Plata basin of southeastern South America. This study extends the analysis of this "South American Seesaw" precipitation dipole to relationships between the SACZ and large, long-lived mesoscale convective systems (LLCSs) over the La Plata basin. By classifying SACZ events into distinct continental and oceanic categories and building a logistic regression model that relates LLCS activity across the region to continental and oceanic SACZ precipitation, a detailed account of spatial variability in the out-of-phase coupling between the SACZ and large-scale organized convection over the La Plata basin is provided. Enhanced precipitation in the continental SACZ is found to result in increased LLCS activity over northern, northeastern, and western sections of the La Plata basin, in association with poleward atmospheric moisture flux from the Amazon basin toward these regions, and a decrease in the probability of LLCS occurrence over the southeastern La Plata basin. Increased oceanic SACZ precipitation, however, was strongly related to reduced atmospheric moisture and decreased probability of LLCS occurrence over nearly the entire La Plata basin. These results suggest that continental SACZ activity and large-scale organized convection over the northern and eastern sections of the La Plata basin are closely tied to atmospheric moisture transport from the Amazon basin, while the warm coastal Brazil Current may also play an important role as an evaporative moisture source for LLCSs over the central and western La Plata basin.
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Directory of Open Access Journals (Sweden)
Ana Julia Atucha
2011-12-01
Full Text Available El objetivo de este documento es analizar si la participación de los beneficiarios del Partido de General Pueyrredon en el Seguro de Capacitación y Empleo implicó mejoras en su empleabilidad. En particular, se examinan las relaciones entre formación y empleo de este colectivo, como aproximación a la medición del impacto de esta política de mercado de trabajo en Mar del Plata. La información utilizada se basa en la "Encuesta de Informalidad y Beneficiarios de Programas Sociales" en el aglomerado, llevada a cabo en octubre de 2009 por el Grupo Estudios del Trabajo de la Facultad de Ciencias Económicas y Sociales de la Universidad Nacional de Mar del Plata, en el marco de un proyecto en convenio con la OIT. Esta fuente primaria fue complementada por entrevistas telefónicas a destinatarios seleccionados. El acercamiento se efectuó a través de una exploración de las trayectorias formativas seguidas por los destinatarios, de la valoración que ha tenido la capacitación respecto a la mejora sobre su empleabilidad y de la tarea de vinculación entre demandantes y oferentes que realiza la Oficina de Empleo. Entre los principales resultados se detectaron gran proporción de beneficiarios sin una trayectoria formativa que los califique sobre un oficio, percepciones negativas respecto a su empleabilidad y situaciones de inactividad. El documento deja planteada la necesidad de optimizar las tareas de orientación y vinculación al mercado de trabajo para mejorar la situación del grupo bajo análisis.This paper is aimed to analyze whether the participation of beneficiaries in the Training and Employment Insurance improved their employability. In particular, the relationship between training and employment of this group, as an approach to measuring the effect of this labor market policy in Mar del Plata, will be examined. The information come from the "Survey of Informality and Beneficiaries of Social Programs" collected in Mar del Plata
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Recent La Plata basin drought conditions observed by satellite gravimetry
L. Chen , J.; R. Wilson , C.; D. Tapley , B.; Longuevergne , L.; L. Yang , Z.; R. Scanlon , B.
2010-01-01
International audience; The Gravity Recovery and Climate Experiment (GRACE) provides quantitative measures of terrestrial water storage (TWS) change. GRACE data show a significant decrease in TWS in the lower (southern) La Plata river basin of South America over the period 2002-2009, consistent with recognized drought conditions in the region. GRACE data reveal a detailed picture of temporal and spatial evolution of this severe drought event, which suggests that the drought began in lower La ...
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Directory of Open Access Journals (Sweden)
Javier Planas
2007-12-01
Full Text Available Se describe y analiza el tratamiento que los documentos audiovisuales reciben, a través de las políticas de desarrollo de colecciones, los procesos técnicos y los servicios, en una muestra de bibliotecas populares de la ciudad de La Plata. Se señala la existencia de un panorama común a la mayor parte de las bibliotecas. Se destacan las características de dos instituciones que se constituyen como excepciones a esta generalidad.The treatment received by audiovisual documents is described and analyzed in relation with the policies of collection development, technical processes and services, in a sample of popular libraries located in La Plata City. The existence of a common picture in the great majority of these libraries is corroborated. The characteristics of two of the libraries are noted as exceptions to the general situation.
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Material tipo de la Colección de Herpetología del Museo de La Plata, Buenos Aires, Argentina
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Ferraro, Daiana Paola
2005-12-01
Full Text Available El Museo de la Plata (Buenos Aires, República Argentina se fundó en 1889, y la colección herpetológica comenzó a funcionar poco tiempo después, bajo la responsabilidad deJulio G. Koslowsky. En esta contribución se listan los ejemplares tipo de Anfibios y Reptiles depositados en la colección herpetológica del Museo de La Plata. El material tipo depositado corresponde a 32 especies descriptas desde 1895 hasta la actualidad, incluyendo: 14 holotipos, 115 paratipos, 4 lectotipos, 22 paralectotipos, 1 neotipo y 12 sintipos (sin incluir los ejemplares extraviados. Se proporciona, para cada taxón, la información completa referida a estatus de cada ejemplar tipo, sexo, datos de recolección y modificaciones taxonómicas posteriores. The La Plata Museum (Buenos Aires, República Argentina was founded on 1889, and after a little time, the herpetological collection started under the responsibility of Julio G. Koslowsky. In this paper the type specimens of Amphibia and Reptilia housed in the collection of the Herpetology Section at the La Plata Museum are listed. These type materials correspondto 32 species described since 1895 until nowadays, and include: 14 holotypes, 115 paratypes, 4 lectotypes, 22 paralectotypes, 1 neotype and 12 sintypes (this list does not include lost specimens. Complete data about taxonomic status, sex, collection data, and subsequent taxonomic changes are given for each taxon.
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Rio de la Plata river: as paleoenvironmental focus using diatoms as proxies
International Nuclear Information System (INIS)
Perez, L; Garcia-Rodriguez, F; Hanebuth, T.
2012-01-01
The objective of this study is the reconstruction of the environmental history of the Rio de la Plata system in relation to the anthropogenic impact and historical changes in the flow with emphasis on salinity variations during the late Holocene. For this reason it was analyzed the composition of diatoms (grouped in freshwater (D), saline (S) and marine (M))
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Determinantes de la morosidad tributaria en Mar del Plata
Mallo, Paulino E.; Artola, María Antonia; Zanfrillo, Alicia Inés; Morettini, Mariano; Galante, Marcelo Javier; Pascual, Mariano Enrique; Busetto, Adrián Raúl
2011-01-01
El objetivo del artículo es analizar, a través de la aplicación de lógica difusa y de herramientas estadísticas, el comportamiento de los indicadores contables de las PyMEs marplatenses, ya que los mismos pueden incidir en la determinación de la morosidad en el pago de tributos nacionales, provinciales o municipales. Para ello, se trabaja con una muestra de empresas representativas de distintos sectores productivos de la ciudad de Mar del Plata, que incluye organizaciones de distinto tamaño y...
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Simulation of the transport of suspended particulate matter in the Rio de la Plata
Energy Technology Data Exchange (ETDEWEB)
Hausstein, H.
2008-11-06
Numerical simulations of the transport of Suspended Particulate Matter in the Rio de la Plata estuary were performed with a three dimensional model for coastal waters driven by wave sand currents. Aturbulence based flocculation approach is implemented to the model. The model is for the first time applied under heavy conditions, since the Rio de la Plata has discharges up to 25000 m{sup 3}/s and SPM concentrations up to 300-400 mg/l. Such concentrations are also difficult to compute from satellite measurements. SeaWiFs satellite images served for the validation of the model results. The model is able to reproduce the shape and the position of the front as well as the zone of the turbidity maximum. It also identifies the zones of erosion and deposition which is of significant importance because of the dense ship traffic along the navigational channels towards Buenos Aires and the cities upstream the rivers. (orig.)
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Undergraduate education and training in optics at the Universidad Nacional de La Plata
Garavaglia, Mario
2000-06-01
After few historical and statistical data related to the Universidad Nacional de La Plata, follows a description of activities on undergraduate training in Optics at the Laboratorio de Optica, belonging to the Faculty of Astronomical and Geophysical Sciences, and on undergraduate education in Optics at the Departamento de Fisica, belonging to the Faculty of Exact Sciences.
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Ambientes de sedimentación vinculados al acuífero Puelche en la región de La Plata
García, Juan Manuel; Kruse, Eduardo; Deluchi, Marta
2016-01-01
Se plantea una actualización de las características dimensionales e interpretación del ambiente de sedimentación en función de las características morfológicas de la base y el techo del Acuífero Puelche en el área abarcada por las cuencas hidrográficas que drenan hacia el Río de la Plata en los Partidos de Berisso, Ensenada y La Plata (Provincia de Buenos Aires). La metodología incluyó la recopilación y revisión de perfiles de perforación antiguos y recientes, los cuales permitieron la elabor...
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Mabel Irma Contin
2011-01-01
Full Text Available Este artículo presenta los resultados de una investigación sobre las transformaciones y tensiones en el espacio público central cuyo propósito ha sido descubrir, finalmente, los valores en juego en la gestión contemporánea del paisaje cultural urbano. Dicha investigación toma como caso de estudio la ciudad de La Plata (Argentina y su principal parque urbano, el Paseo del Bosque. Éste contiene en uno de sus bordes al estadio de fútbol del Club Estudiantes de La Plata, uno de los equipos emblemáticos de la ciudad, cuyo proyecto de renovación ha originado un conflicto urbano de una dificultad sin precedentes.
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Archivo de placas astrométricas del Observatorio de La Plata
di Sisto, R.; Orellana, R. B.
Se ha realizado una base de datos con las placas fotográficas obtenidas con el Astrográfico del Observatorio de La Plata. Se han clasificado un total de 3000 placas obtenidas para asteroides y cometas. El acceso a la base de datos se hará por FTP y la misma contendrá la siguiente información: fecha y tiempo de exposición, coordenadas del centro de placa, tipo de emulsión fotográfica, estado de la placa, objeto fotografiado.
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Irina Podgorny
1999-06-01
Full Text Available En este trabajo se analizan los criterios de organización de las colecciones antropológicas del Museo de La Plata vigentes entre 1897 y 1930. Bajo el nombre de ‘antropológicas’ se incluyen las colecciones correspondientes a las exhibiciones de las salas de antropología, etnografía y arqueología. Aunque el criterio que finalmente imperó fue el ordenamiento por regiones geográficas, según el sistema de Enrique Delachaux, se discutirán además las otras posibilidades de ordenamiento (etnológico, lingüístico y cronológico que aunque conocidas por las autoridades y científicos del Museo de La Plata fueron descartadas.The article analyzes the criteria for arranging and classifying anthropological collections (that is, anthropology, ethnography, and archeology exhibit rooms adopted at the Museo de La Plata during 1897-1930. The criterion ultimately selected was arrangement by geographical regions, using a system devised by Enrique Delachaux. The article examines other rules of classification as well, familiar to the museum’s curators and scientists but rejected by them: ethnological, linguistic, and chronological criteria.
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The influence of abiotic factors present in the Rio de la Plata over the chromium genotoxicity
International Nuclear Information System (INIS)
Lopez, L.C.; Moretton, J.
1997-01-01
The alterations suffered by the well-known environmental genotoxic agent, Cr(V I), were studied. Cr(V I) salts were dissolved in water effluent river receptors waters such as from the Rio de la Plata. The influence of abiotic factors present in this kind of water was evaluated using the Rec. assay in Bacillus subtilis. The results detected a soluble fraction that potentiated Cr(V I) genotoxicity. This substance (or group of substances) is sensible to sterilization by heat and UV radiation, and its activity seems to decrease with particulate matter. Its genotoxicity was not affected by high concentrations of particulate matter in the Rio de la Plata water. In samples where chromium salts were added to raw river water, abiotic interference due to sterilization process occurred. A decrease in genotoxicity was found after filtration through inorganic filters (0.22 μ m) and an increase was noticed after exposure to UV radiation. (Author)
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Ana Salazar Martínez
2007-07-01
Full Text Available En esta nota se aporta información sobre los oribátidos arborícolas del Paseo del Bosque, La Plata, Argentina (34º 54' S, 57º 55' W, a partir de muestreos realizados en suelos suspendidos con distinta concentración de detritos. La fauna de oribátidos estuvo representada por 17 especies, siendo Cultroribula sp., Pheroliodes cf. minutus Baranek, Rhysotritia peruensis Hammer y Oppiella nova Oudemans las de mayor importancia relativa. De las especies registradas, 76 % son propias del ambiente arborícola.This work deals with the arboreal oribatids of «Paseo del Bosque», La Plata, Argentina (34º 54' S, 57º 55' W. Samples were taken from suspended soils exhibiting unequal detritus concentrations. The overall sample included 17 oribatid species, exhibiting Cultroribula sp., Pheroliodes cf. minutus Baranek, Rhysotritia peruensis Hammer and Oppiella nova Oudemans the highest relative importance. Seventy percent of the recorded species are representative of the arboricole environment.
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Gustavo Politis
2014-12-01
Full Text Available Normal 0 21 false false false ES-AR X-NONE X-NONE En este trabajo se estudia el diario del explorador portugués Pero Lopes de Souza en 1531 al Río de la Plata y al delta Inferior del río Paraná desde una perspectiva histórica y arqueológica. Este relato es el único documento de la época escrito en tiempo real por un testigo directo de los acontecimientos que describe y por lo tanto es una fuente de calidad superlativa para conocer los primeros momentos de la exploración europea en el Río de la Plata y para abordar el estudio de los indígenas que habitaban el área a principios del siglo XVI. En este artículo se resumirán y discutirán las observaciones de Lopes de Sousa en el contexto de la historia del Río de La Plata en la primera mitad del siglo XVI y de las investigaciones arqueológicas recientes. Palabras clave: chana-timbú, arqueología del NEA, crónicas siglo XVI Abstract In this paper the diary of the Portuguese explorer Pero Lopes de Sousa to the La Plata River and to the Lower Delta of the Paraná River is analyzed from a historical and archaeological perspective. This narrative is the only document written in real time from a direct witness of the accounts he described. Therefore it is a unique high-quality source to know about the early times of the European Conquest to the La Plata River and to approach the study of the indigenous people of the area at the beginning of the XVI Century. In this article, the observations and comments from Lopes de Souza are summarized and analyzed within the context of the history of the first half of the XVI Century and in the light of the recent archaeological investigations. Keywords: chaná-timbú, archaeology of Northeastern Argentina, XVI Century Chronicles
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Evaluación de la vulnerabilidad socio-ambiental del periurbano de Mar del Plata
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Daiana Daga
2015-12-01
Full Text Available RESUMEN El periurbano de Mar del Plata conforma un espacio dinámico y heterogéneo, susceptible a distintas intervenciones que pueden generar impactos ambientales con consecuencias negativas sobre la población expuesta. El presente trabajo evalúa la vulnerabilidad socio-ambiental del periurbano marplatense en 2010, distinguiendo sectores críticos y principales aspectos que determinan las condiciones extremas. Para ello se construyó un Índice de Vulnerabilidad Socio-Ambiental (IVSA y se examinó su distribución espacial.La vulnerabilidad socio-ambiental hace referencia a las condiciones de la población y su entorno inmediato para enfrentar efectos adversos. Las situaciones más críticas (IVSA= 0,46–0,58 pertenecen a los sectores del periurbano definidos por los ejes que conforman las Rutas Nº 226 y Nº 88. Las dimensiones sanitaria, educativa y ambiental determinan en mayor medida la distribución del IVSA. El procedimiento metodológico empleado permitió identificar áreas críticas, siendo transferible a otras situaciones con problemáticas semejantes. ABSTRACT Mar del Plata peri-urban conforms a heterogeneous and dynamic space, susceptible to many interventions that generate significant impacts with negative consequences on the exposed population. This paper evaluates the socio-environmental vulnerability of the Mar del Plata peri-urban in 2010, distinguishing critical sectors and principle aspects that determine the extreme conditions. To this end, it was built a Socio-Environmental Vulnerability Index (SEVI and its spatial distribution was examined. The socio-environmental vulnerability refers to the conditions of the population and their environment to deal with adverse effects. The most critical situations (SEVI= 0.46-0.58 belongs to the peri-urban sectors that were defined by the 226 and 88 roads. The health, education and environmental dimensions determine the SEVI distribution. The methodological procedure employed allowed
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Vásquez Chávez, Elva
2015-01-01
Comparar la efectividad clínica del uso del apósito hidrocoloide vs sulfadiazina de plata en el manejo de quemaduras superficiales de espesor parcial. Este estudio es observacional analítico. 62 pacientes divididos aleatoriamente en grupo de apósito hidrocoloide (DuodermR) o silverdiazina de plata, fueron seguidos hasta presentar una reepitelización completa. Se evaluó las siguientes variables clinico-epidemiológicas: edad, sexo, tipo de tratamiento, localización, tiempo y calidad de epiteliz...
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Susana Ortale
2009-12-01
Full Text Available La mirada estigmatizante de la maternidad en la adolescencia y el interés por controlar la sexualidad por parte del sector sanitario, es reciente y diferente para hombres y mujeres. Sabemos que las categorías género y edad, en tanto construcciones culturales que aluden a relaciones básicas de desigualdad -atravesadas por estructuras económico-políticas particulares-, están cargadas de significados que se dirimen en un campo social predispuesto a reforzar estereotipos naturalizantes y relaciones de dominación. El estudio se ubica en la problemática general del reconocimiento de derechos presente en los programas de salud sexual y reproductiva que tienen como destinatarias a mujeres adolescentes pobres. El recorte pone en foco el contraste entre el marco normativo y el significado que asume la maternidad para las adolescentes. Para ello, se analizan programas de salud nacionales, de la Pcia. de Buenos Aires y de la municipalidad de La Plata y discursos obtenidos en entrevistas realizadas a veinte adolescentes residentes en barrios pobres de la ciudad de La Plata. El análisis de los programas explora la incorporación del enfoque de género y la interpretación de los problemas de sexualidad/reproducción de l@s adolescentes en el marco de los derechos humanos y el de los discursos de las entrevistadas indaga su interpelación.Stigmatizing gaze of teenage motherhood and the aim to control the sexuality from the health sector, is recent and different for men and women. We know that gender and age categories, as cultural constructions that refer to basic relations of inequality-crossed by particular political-economic structures, are loaded with meanings that are settled in a social and naturalizing field predisposed to reinforce stereotypes and relations of domination. The study is placed in the general problem of aknowledgement of rights in the programs of sexual and reproductive health in adolescent girls from low environment. This frame
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Hernández, Mario Alberto; Giai, Santiago B.
1996-01-01
Se analiza la recarga potencial de aguas subterráneas sobre un perfil entre La Plata y Santa Isabel (Buenos Aires y La Pampa). El mismo tiene la particularidad de ser perpendicular a las isohietas, extendiéndose desde una zona húmeda lindante con el río de la Plata, hasta otra de fuerte aridez y continentalidad, unos 900 km al Oeste. Algunos de los factores influyentes en el monto de la recarga tienen el mismo valor en todo el perfil, alcanzando su intervención igual peso en todas las local...
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Los torques de plata de Monasterio de Rodilla
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Castillo, Belén
1996-12-01
Full Text Available The silver torques coming from Monasterio de Rodilla (Burgos are an excepcional ensemble of the jewellery before Roman times in the northern Meseta. These pieces, wrought of rolled up braiding wires, belong to a fully-developed process in which the Iberian and Mediterranean influences become transformed by the local style and give rise to special and typical models of the Celtiberic jewellery.Los torques de plata procedentes de Monasterio de Rodilla (Burgos constituyen un conjunto excepcional de la orfebrería prerromana de la Meseta Norte. Estas piezas, elaboradas con alambres trenzados y enrollados, responden a un proceso evolucionado en el que las influencias ibéricas y mediterráneas, transformadas por el gusto local, dan lugar a modelos propios y característicos de la orfebrería celtibérica.
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Flores, Constanza Y.
2014-01-01
El objetivo general del presente Trabajo de Tesis fue la preparación y caracterización de superficies sólidas modificadas con nanopartículas de plata con potenciales aplicaciones en Biomedicina. Para esto se optimizó el método de síntesis de nanopartículas de plata (NPs Ag) recubiertas con citrato, obteniendo NPs Ag monodispersas de 6 ± 2 nm de diámetro recubiertas con citrato y estables en medios acuosos. Asimismo, se estudió la inmovilización de estas NPs Ag sobre superficies de Ti/TiO2, en...
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Protección ambiental del Río de la Plata y su frente marítimo: el marco jurídico general
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Heber Arbuet Vignali
2014-07-01
Full Text Available Versión escrita de la conferencia dictada en el Simposio sobre aspectos jurídicos de la protección ambiental del Río de la Plata y su Frente Marítimo (Montevideo: 21 nov.2001Contenido: Introducción. Importancia del derecho en las relaciones humanas. Importancia del derecho en el asunto que nos convoca. El polifacético marco jurídico de este proyecto. La aparición de los nuevos sistemas. La nueva realidad socio política que debe ser regulada jurídicamente. Importancia de estas ideas para la protección ambiental en el Plata
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Cenozoic deposits exposed along Rio de la Plata coast in the Canelones Department (Uruguay)
International Nuclear Information System (INIS)
Goso Aguilar, C.; Spoturno, J.
2004-01-01
This paper allows to know some sedimentological and stratigraphical features of the Cenozoic deposits exposed along Rio de la Plata coast in the Canelones department, Uruguay. The results, mainly collected from metric thickness of local stratigraphical sections and coastal outcrops of that region are presented. Both Tertiary and Quaternary sediments are present, however transitional Pleistocenic deposits of Chuy Formation and continental sediments of Libertad Formation are more dominant [es
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Energy Technology Data Exchange (ETDEWEB)
Bocanegra, E.; Martinez, D. E. [Instituto de Geologia de Costas y del Cuaternario, UNMDP (Argentina); Pool, M.; Carrera, J. [Instituto de Diagnostico Ambiental y Estudios del Agua, CSIC (Spain)
2013-07-15
Over-exploitation in the coastal aquifer in Mar del Plata, Argentina, led to a seawater intrusion process affecting groundwater by salinization. The aim of this paper is to show the contribution of isotopic techniques to generate the numerical flow and transport model of the Mar del Plata aquifer. On the basis of the hydrogeological conceptual model, a numerical model was constructed. It consists of a multilayer aquifer in the urban area with 2 layers separated by an aquitard and a monolayer aquifer in the rest of the basin. The isotopic difference recorded in groundwaters allow the identification of the origin of the recharge and the confirmation of the presence of the hydrogeological environments incorporated in the numerical model. Flow simulation reflects the evolution of piezometric heads. Chloride transport simulation represents the salinization process due to seawater intrusion and the subsequent backward movement of the interface due to the abandonment of salinized wells. The results of numerical simulation confirm the conceptual model and reproduce the impact of the adopted management strategies. (author)
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Clarke, R. T.
2012-04-01
During the voyage of HMS Beagle, Charles Darwin sailed in a small boat along the River Paraná, a major tributary of the la Plata drainage system. He wrote about the occurrence of severe droughts (the latest of which had been termed the "gran seco") alternating with periods of severe flooding. From reports received, he concluded that these events appeared to be cyclic with a period "of about fifteen years". Because extended periods of low flow in Brazilian rivers are of immense economic importance, the presentation describes a search for the material which led Darwin to this conclusion. A prolonged period of low flow in another la Plata tributary - the River Paraguay - not unlike the "gran seco" reported by Darwin, has occurred more recently; if such low flows were to recur in the future, the consequences would be severe for a region where more than 70% of energy is supplied by hydropower. A priori considerations suggest the use of statistical long-memory models for predicting River Paraguay water-levels, and some preliminary results from their use are presented.
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Miradas Caleidoscópicas sobre el Chagas. Una experiencia educativa en el Museo de La Plata
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Mariana Sanmartino
2012-01-01
Full Text Available Presentamos resultados y reflexiones en torno a la experiencia "Semana del Chagas en el Museo de La Plata" (La Plata, Provincia de Buenos Aires, Argentina realizada en mayo de 2011. La propuesta tuvo como objetivo la difusión y sensibilización acerca de la problemática del Chagas desde una mirada integral. Las actividades incluyeron una muestra de obras plásticas; la proyección de materiales audiovisuales innovadores; talleres con estudiantes de escuelas primarias y secundarias de la zona; charlas abiertas a cargo de especialistas; la presentación y distribución de materiales didácticos a docentes de escuelas; así como el desarrollo de actividades destinadas al público general. La evaluación de la experiencia es altamente satisfactoria, y de la reflexión sobre lo transitado -durante la organización y en la implementación- surgen múltiples aprendizajes tanto para participantes como para organizadores, de lo cual se desprende el interés por compartir la propuesta y la posibilidad de adecuarla a otros contextos.
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Carbonari, Fabiana Andrea; Grandis, María Belén de
2015-01-01
El presente artículo se inscribe en el plan de trabajo de la Beca Interna de Entrenamiento en Investigación de la FAU denominada Italianos en la ciudad de La Plata. El caso del Banco Provincia de la ciudad de La Plata que, durante el ciclo lectivo 2015 desarrolla la Arq. María Belén de Grandis con dirección de la Esp. Arq. Fabiana Carbonari. La misma tiene por objetivo realizar el estudio histórico sistemático del Banco de la Provincia de Buenos Aires. En ese sentido, propone analizar las tra...
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Mar del Plata (Argentina y Málaga (España. Estudio comparado de dos destinos turísticos
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Fernando Almeida García
2014-01-01
Full Text Available Se estudia y compara la evolución de dos destinos que presentan similitudes en su historia turística, en su tamaño demográfico y función territorial. A pesar de las similitudes de Málaga y Mar del Plata, éstas presentan comportamientos singulares en su evolución. Se toma como referencia de estudio el modelo de Butler. En el caso de Málaga es esencial conocer la relación que ha mantenido con Torremolinos y la Costa del Sol, para poder entender la evolución del destino. En el caso de Mar del Plata es importante entender el papel de la demanda nacional y las decisiones políticas que derivaron en la popularización del destino. Así mismo, se analiza el papel que ha jugado las segundas residencias y los procesos de urbanización en la evolución de los destinos turísticos.
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Mar del Plata (Argentina: la ciudad balnearia de los porteños en el Atlántico suroccidental
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Yvanne Bouvet
2005-01-01
Full Text Available Nacida a fines del siglo 19, Mar del Plata ha devenido en el término de un siglo en balneario por excelencia de Buenos Aires y de la Argentina en general. La cultura estival de la playa la ha hecho evolucionar desde un turismo elitista hacia un turismo de masas, impulsando el desarrollo de espacios y estructuras destinadas a alojamiento y ocio para cerca de 3 millones de personas cada año. Con un espacio urbano fuertemente segregativo y en expansión, el litoral está sometido a una fuerte presión antrópica, a una erosión contínua y a una degradación en la calidad de sus aguas. La crisis social, económica y política que atraviesa Argentina crea condiciones poco favorables para la actividad turística y ensombrece el futuro de Mar del Plata.
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Liliana A. Fernández
2004-07-01
Full Text Available Se examinaron los ejemplares tipo depositados en la colección de la División Entomología del Museo de La Plata, pertenecientes a diversas especies nominales de Byrrhoidea: Dryopidae (1 especie, 1 ejemplar tipo, Elmidae (4, 9, Limnichidae (29, 47 y Psephenidae (1, 2. El material tipo fue estudiado por los siguientes autores: Pic, Spangler, Spangler & Brown, Spangler & Perkins, Spangler & Santiago, Spilman y Wooldridge. Para cada taxón se indica la publicación original, datos de colección y condición del material.The types of species of Byrrhoidea (Coleoptera housed in the collection of the División Entomología of Museo de La Plata were examined and listed. They belong to 35 species distributed in the families Dryopidae (1 species, 1 type, Elmidae (4, 9, Limnichidae (29, 47 and Psephenidae (1, 2. The types were described by Pic, Spangler, Spangler & Brown, Spangler & Perkins, Spangler & Santiago, Spilman, and Wooldridge. For each taxon, complete information about categories of types, reference original descriptions, collection data and specimen condition are given.
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La industria del Gran La Plata según el último Censo Nacional Económico
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Diego Arturi
2012-12-01
Full Text Available El artículo tiene como objetivo caracterizar el sector industrial del Gran La Plata en base a información del último Censo Nacional Económico (CNE 2004/2005. En una primer parte se identifican las principales características del sector industrial a escala nacional en los períodos neoliberal y posconvertibilidad, a partir de bibliografía especializada y análisis de series estadísticas e informes técnicos. En una segunda parte se analiza el sector industrial del Gran La Plata en base a entrevistas a informantes calificados y a los datos censales según cantidad de establecimientos, puestos de trabajo ocupados, rama de actividad, tamaño de los locales industriales, productividad y especialización industrial de los municipios; asimismo se realiza una aproximación a niveles de intensidad tecnológica por rama. A partir de este análisis se pueden destacar las siguientes conclusiones: predominio de las micro y pequeñas empresas, productividad superior al promedio nacional, escaso aporte de las ramas de alta intensidad tecnológica y ausencia de especialización que impide definir un perfil industrial marcado.
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Resiliencia y engagement en el sector hotelero en la ciudad de Mar del Plata
Redondo, Ana Isabel; Arraigada, Mariana Cecilia
2015-01-01
Desde el marco de la psicología de la salud ocupacional positiva, nos proponemos realizar un estudio descriptivo sobre las variables resiliencia y engagement en el sector hotelero de la ciudad de Mar del Plata. Para tal fin, se utilizaran dos instrumentos con formato de cuestionario auto-administrado, a saber: RSA (Escala de Resiliencia en Adultos) y UWES (Utrech Work Engagement Scale) que miden dichas variables a aplicar en una muestra compuesta por 80 personas, todas ellas empleados de dos ...
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Gabriel Genzano
2011-11-01
Full Text Available This study describes the macrofaunal assemblages of subtidal rocky reefs off Mar del Plata in order to compare the macro invertebrate assemblages settled on shipwrecks with those of nearby reef sand to characterize the fish fauna associated with natural (NR and artificial (AR reefs. Topographic characterizations and surveys of invertebrates and fishes were performed in November and December 2005, using SCUBA diving. A non-parametric multivariate analysis was used to analyze the environmental and biological data. The reefs were mainly distinguished by their depth and the position of the substrate. The red calcareous algae, Corallina officinalis, dominated the shallowest NR, whereas conspicuous mytilid assemblages of Mytilus platensis were present at depths over 3 m, sea anemones, Anthothoe chilensis, were more abundant between 6 and 10 m, and the soft coral, Tripalea clavaria, was found at nearly 20 m depth. No differences were found between horizontal ARs and the adjacent NRs. The greatest differences were found between the communities of vertical and horizontal substrates, both in NRs and ARs. Fifteen fish species were recorded in the analyzed area. Species having strong site fidelity, e.g., Acanthistius brasilianus and Pseudopercis semifasciata, were clearly more abundant and/or frequent in ARs (shipwrecks than in NRs. This pioneer study in the surveyed area showed that reef sallow the settlement of diverse benthic assemblages. ARs also provide refuge for fishes. As sport fishing and diving are activities being carried out in Mar del Plata, where tourism is one of the main economic resources, the protection of such areas should be considered in conservation plans.Se describió la macrofauna de los arrecifes rocosos sublitorales, frente a Mar del Plata, para comparar las asociaciones de macro-invertebrados de los pecios con las de los arrecifes aledaños y caracterizar la fauna de peces tanto en los arrecifes naturales (NR como artificiales (AR
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Graciela Iris Zuppa
2011-08-01
Full Text Available Cette étude propose une lecture interprétative de l’histoire urbaine et culturelle de Mar del Plata, un territoire dont le paysage côtier a connu d’importances modifications. Dans ce contexte de transformation, l’article étudie les pratiques publicitaires qui contribuent à la compréhension des caractéristiques de cet endroit, dans le but de proposer des interprétations autour des changements dans la construction de l’image de la ville, les représentations sociales qui les supportent, les codes visuels et discursifs utilisés pour les transmettre.Pour atteindre ces objectifs, l’auteur analyse les émetteurs de messages, les images et les textes qui les accompagnent, le lien entre les deux instances, et l’interprétation qui émane d’elles. La récupération et la lecture interprétative de pièces graphiques, élaborées pour promouvoir la ville, permettent d’identifier et d’interpréter les caractéristiques fondamentales de la transition d’une station balnéaire élitiste qui devient une station qui se popularise. Par conséquent, l’étude des images successives de Mar del Plata entre 1930 et 1945 permet de suivre l’évolution de la station à travers les différentes campagnes definies par les politiques touristiques du gouvernement et les entreprises privées.This work proposes an interpretative reading of the urban and cultural history of Mar del Plata, a territory whose coastal scenery has been modified in a very important way. Once in this transformational context, we will analyse the advertising practices that contribute to understand the characteristics of the area, in order to offer an interpretation of the changes undergone in the construction of the city image, the social representations that support them and the visual and discursive codes used to transmit them.In order to achieve those aims, we are going to analyse the producers of those messages, the images and the written texts that are included
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Transformaciones territoriales en el periurbano de Mar del Plata
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Laura Zulaica
2012-01-01
Full Text Available El estudio de las transformaciones territoriales de las áreas periurbanas demanda el conocimiento de la evolución de las actividades que allí se desarrollan. El presente trabajo analiza las transformaciones del periurbano de Mar del Plata entre los noventa y la actualidad, enfatizando en los cambios de las actividades. Para ello, se realiza una clasificación supervisada de usos sobre imágenes satelitales de 1989 y 2009, que es ajustada a partir de una base de datos del área. Posteriormente, se analizan las transformaciones considerando distintas fases de estructuración de las ciudades y se establece una periodización siguiendo las nociones de régimen y ruptura. El estudio realizado constituye una base para generar estrategias de ocupación y desarrollo del área y la metodología aplicada puede extenderse a otros territorios
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Silvia Albornoz
2002-12-01
Full Text Available La búsqueda de información y sus problemas colaterales inciden en el desarrollo de la actividad de los investigadores. Nos proponemos analizar esta temática a través del estudio de las pautas de comportamiento de investigadores de la Facultad de Humanidades y Ciencias de la Educación de la Universidad de La Plata, para identificar conductas informativas y al mismo tiempo detectar obstáculos que impiden el aprovechamiento óptimo de la Biblioteca Central y las Bibliotecas Departamentales de la Institución. Los resultados obtenidos servirán de base para definir indicadores de calidad aplicables a la mejora continua de los servicios de biblioteca. Como resultado del análisis de metodologías aplicadas en estudios de usuarios se determinó combinar las perspectivas cuantitativa y cualitativa en este trabajo en curso = The search of information and its collateral problems affect the development of the researchers activity. We would like to analyze this subject through the study of the behavior guidelines of researchers of the Faculty of Humanities and Education Sciences of the University of La Plata, in order to identify informative behavior and, at the same time, to find out the obstacles that avoid the optimal use of the Central Library and the Departmental Libraries of the Institution. The obtained results will serve as a base to define quality indicators applicable to the continuous improvement of the library services. As a result of the analysis of methodologies applied to user studies, it was decided to combine the quantitative and qualitative perspectives in this work.
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Silvia Albornoz
2002-12-01
Full Text Available La búsqueda de información y sus problemas colaterales inciden en el desarrollo de la actividad de los investigadores. Nos proponemos analizar esta temática a través del estudio de las pautas de comportamiento de investigadores de la Facultad de Humanidades y Ciencias de la Educación de la Universidad de La Plata, para identificar conductas informativas y al mismo tiempo detectar obstáculos que impiden el aprovechamiento óptimo de la Biblioteca Central y las Bibliotecas Departamentales de la Institución. Los resultados obtenidos servirán de base para definir indicadores de calidad aplicables a la mejora continua de los servicios de biblioteca. Como resultado del análisis de metodologías aplicadas en estudios de usuarios se determinó combinar las perspectivas cuantitativa y cualitativa en este trabajo en curso.The search of information and its collateral problems affect the development of the researchers activity. We would like to analyze this subject through the study of the behavior guidelines of researchers of the Faculty of Humanities and Education Sciences of the University of La Plata, in order to identify informative behavior and, at the same time, to find out the obstacles that avoid the optimal use of the Central Library and the Departmental Libraries of the Institution. The obtained results will serve as a base to define quality indicators applicable to the continuous improvement of the library services. As a result of the analysis of methodologies applied to user studies, it was decided to combine the quantitative and qualitative perspectives in this work.
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La introducción de las telecomunicaciones eléctricas en el Río de la Plata
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Ariel Sar
2013-03-01
Full Text Available Las telecomunicaciones eléctricas fueron introducidas en las repúblicas del Río de la Plata entre 1864 y 1866. Primero Paraguay instaló el ferrocarril, la telegrafía eléctrica y una fundición de acero para fabricar armas y tecnología pesada. A los pocos meses, capitales británicos instalaron una red telegráfica eléctrica entre la Argentina y Uruguay, en el marco de una estrategia de desarrollo económico y de dominación imperial para establecer redes de expansión global conformadas por los telégrafos, los puertos y los ferrocarriles. Estos eventos tecnológicos se produjeron en el marco de un conflicto creciente entre facciones de Argentina, Brasil y Uruguay que desembocaron en la Guerra de la Triple Alianza contra Paraguay, conflagraciones de las que participaron, de una u otra manera, Gran Bretaña y Francia. Las guerras de soberanía rioplatense y la competencia entre potencias europeas impulsa, pues, una revolución tecnológica en el Plata en el campo de las comunicaciones.
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International Nuclear Information System (INIS)
Burone, L.; Franco-Fraguas, P.; Garcia-Rodriguez, F.; Venturini, N.; Brugnoli, E.; Muniz, P.; Ortega, L.; Marin, Y.; Mahiques, M.; Nagaic, R.; Bicegoc, M.; Figueiras, R.; Salaroli, A.
2012-01-01
The terrigenous proxies contribution, the organic matter origin, the productivity, the hydrodynamic and the biological records were used to determine the imrprint of the continental influence along the Rio de la Plata and the Continental Atlantic
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Assessing residual hydropower potential of the La Plata Basin accounting for future user demands
Popescu, I.; Brandimarte, L.; Perera, M. S. U.; Peviani, M.
2012-08-01
La Plata Basin is shared by five countries (Argentina, Bolivia, Brazil, Paraguay and Uruguay), which have fast growing economies in South America. These countries need energy for their sustainable development; hence, hydropower can play a very important role as a renewable clean source of energy. This paper presents an analysis of the current hydropower production and electricity demand in La Plata Basin (LPB), and it analyses the maximum and residual hydropower potential of the basin for a horizon of 30 yr (i.e. year 2040). Current hydropower production is estimated based on historical available data, while future energy production is deduced from the available water in the catchment (estimated based on measured hydrographs of the past years), whereas electricity demand is assessed by correlating existing electricity demand with the estimated population growth and economic development. The maximum and residual hydropower potential of the basin were assessed for the mean annual flows of the present hydrological regime (1970-2000) and topographical characteristics of the area. Computations were performed using an integrated GIS environment called VAPIDRO-ASTE released by the Research on Energy System (Italy). The residual hydropower potential of the basin is computed considering first that the water supply needs for population, industry and agriculture are served, and then hydropower energy is produced. The calculated hydropower production is found to be approximately half of the estimated electricity demand, which shows that there is a need to look for other sources of energy in the future.
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Gravimetric study on the western edge of the Rio de La Plata craton
International Nuclear Information System (INIS)
Rame, G; Miro, R
2010-01-01
This work is about the gravimetric study on the western edge of the Rio de la Plata craton which belongs to the Gondwana fragment in the south of Brazil, Uruguay and central eastern of Argentina. The work consisted of a survey of 332 gravimetric and topographic stations extended from the western edge of the Sierra Chica de Cordoba up to 200 km east on the pampas. The gravity values observed (gobs) were obtained using a LaCoste §Rom berg gravimeter G-961 and 200T Sodin both with 0.01 mGal, referred to IGSN71 (International Gravity Standardization Net 1971) network
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Ibáñez Puy, Elia
2016-01-01
Este trabajo se centra en la síntesis en vía húmeda para la obtención de nanopartículas estables y con una morfología controlada. Se trabaja con nanopartículas de oro y plata de forma esferoidal, y se realiza un estudio exhaustivo de múltiples factores como la concentración y el pH, para seleccionar el mejor agente encapsulante con el objetivo de obtener un sensor colorimétrico basado en la estabilidad del oro frente a la reactividad de la plata ante el contacto con peróxido de hidrógeno G...
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Satisfacción del cliente de obras particulares de la Municipalidad de La Plata
Pizzorno, Mariano
2013-01-01
Evaluación del nivel de satisfacción de los clientes del servicio de Obras Particulares de la Municipalidad de La Plata en relación a: - El grado de conocimiento de los servicios que brinda el municipio. - La imagen que tiene el ciudadano del municipio. - La importancia de cada atributo del servicio: en relación a la atención al público, a la infraestructura y equipamiento y a los procesos para la realización de trámites. - El grado de satisfacción del ...
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DISPERSIÓN DE LUZ POR UNA NANOPARTÍCULA DE PLATA CON FORMA ESFEROIDAL PROLATA
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Alejandro Castellanos Jaramillo
2016-06-01
Full Text Available Usando el método de diferencias finitas en el dominio del tiempo se estudia la incidencia y dispersión de radiación electromagnética de una nanopartícula de plata con forma esferoidal prolata. Se obtiene la distribución de frecuencias del vector de Poynting dispersado en el régimen casi estacionario y se estudia el estado de radiación de la nanopartícula cuando el pulso de luz ha dejado de perturbarla. Los resultados son de interés didáctico
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DISPERSIÓN DE LUZ POR UNA NANOPARTÍCULA DE PLATA CON FORMA ESFEROIDAL PROLATA
Alejandro Castellanos Jaramillo; Arnulfo Castellanos Moreno
2016-01-01
Usando el método de diferencias finitas en el dominio del tiempo se estudia la incidencia y dispersión de radiación electromagnética de una nanopartícula de plata con forma esferoidal prolata. Se obtiene la distribución de frecuencias del vector de Poynting dispersado en el régimen casi estacionario y se estudia el estado de radiación de la nanopartícula cuando el pulso de luz ha dejado de perturbarla. Los resultados son de interés didáctico
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Diagnóstico estructural de la cadena de valor del turismo de reuniones en La Plata
Lauman, María Victoria
2015-01-01
En el transcurso de la obra se realiza un estudio y una evaluación sobre el estado actual en que se encuentran cada uno de los componentes de la cadena de valor de la cual depende el turismo de reuniones en la ciudad de La Plata, para tomar conocimiento de la oferta turística de reuniones existente en la ciudad y poder contribuir a su mejora. Facultad de Ciencias Económicas
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Molinari, Gloria Edith
2012-01-01
Con el presente trabajo propongo la factibilidad de aplicar un modelo de gestión comúnmente utilizado en las organizaciones privadas a los organismos públicos, en este caso dedicados a la actividad turística. Nos concentraremos en la gestión Municipal del turismo en la ciudad de La Plata. Para ello, utilicé el Manual de Directrices de Municipios Turísticos de la SECTUR, aplicado a la Dirección de Turismo de la Municipalidad de La Plata, con el fin de evaluar diferentes aspectos de l...
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Conflicto de identidad : indefinición sexual en tres poetas de la Edad de Plata
Gómez Garrido, Marta
2013-01-01
Artículo sobre la presencia de un conflicto identitario relacionado con el género en la obra de tres poetas de la llamada Edad de Plata Española: Lucía Sánchez Saornil, Ana María Martínez Sagi y Carmen Conde. Article about the existence of a gender-related identity conflict in three female poets of the Silver Age of Spanish Literature: Lucía Sánchez Saornil, Ana María Martínez Sagi and Carmen Conde.
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Ramiro Saurral
2009-06-01
Full Text Available La Cuenca del Plata provee de agua potable a millones de personas a través de cinco países en Sudamérica. En el contexto de un potencial cambio futuro en las condiciones medias del clima, los caudales de los ríos de la cuenca podrían verse afectados y en este sentido es de sumo interés poder inferir estos posibles cambios en los caudales para década venideras. El objetivo de este trabajo es determinar la habilidad de tres modelos climáticos globales (CNRM-CM3, ECHAM5-MPI/OM y GFDL-CM2.0 en simular los caudales observados de los principales ríos de la Cuenca del Plata. Para ello, se emplearon las salidas de precipitación y temperatura de esos modelos climáticos para forzar un modelo hidrológico distribuido durante la última década del siglo XX (1990- 1999. Los resultados muestran que los tres modelos presentan serias deficiencias en la representación del ciclo hidrológico y que esas diferencias están principalmente explicadas por los importantes errores que tienen en los patrones de precipitación y temperatura sobre el sur de Sudamérica. Esto determina un fuerte impedimento al potencial uso que se podría dar a estos modelos para inferir posibles cambios futuros en los caudales de los ríos de la región.Hydrological modeling is a potent tool that can be useful to, among other things, determine the potential future availability of fresh water on Earth. In particular, the La Plata Basin supplies fresh water to millions of people across five countries. In a context of possible future changes on climate, river streamflows could be affected and in this sense it is of crucial importance to infer these potential changes for the upcoming decades. The objective of this paper is to determine the ability of three climate models (CNRM-CM3, ECHAM5-MPI/OM and GFDL-CM2.0 to simulate the observed discharges of the main La Plata Basin rivers. To force the distributed hydrology model, climate models output data included daily minimum and
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Assessing residual hydropower potential of the La Plata Basin accounting for future user demands
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I. Popescu
2012-08-01
Full Text Available La Plata Basin is shared by five countries (Argentina, Bolivia, Brazil, Paraguay and Uruguay, which have fast growing economies in South America. These countries need energy for their sustainable development; hence, hydropower can play a very important role as a renewable clean source of energy. This paper presents an analysis of the current hydropower production and electricity demand in La Plata Basin (LPB, and it analyses the maximum and residual hydropower potential of the basin for a horizon of 30 yr (i.e. year 2040. Current hydropower production is estimated based on historical available data, while future energy production is deduced from the available water in the catchment (estimated based on measured hydrographs of the past years, whereas electricity demand is assessed by correlating existing electricity demand with the estimated population growth and economic development. The maximum and residual hydropower potential of the basin were assessed for the mean annual flows of the present hydrological regime (1970–2000 and topographical characteristics of the area.
Computations were performed using an integrated GIS environment called VAPIDRO-ASTE released by the Research on Energy System (Italy. The residual hydropower potential of the basin is computed considering first that the water supply needs for population, industry and agriculture are served, and then hydropower energy is produced. The calculated hydropower production is found to be approximately half of the estimated electricity demand, which shows that there is a need to look for other sources of energy in the future. -
Fungal monitoring of the indoor air of the Museo de La Plata Herbarium, Argentina.
Mallo, Andrea C; Elíades, Lorena A; Nitiu, Daniela S; Saparrat, Mario C N
Biological agents, such as fungal spores in the air in places where scientific collections are stored, can attack and deteriorate them. The aim of this study was to gather information on the indoor air quality of the Herbarium of Vascular Plants of the Museo de Ciencias Naturales de La Plata, Argentina, in relation to fungal propagules and inert particles. This study was made using a volumetric system and two complementary sampling methods: (1) a non-viable method for direct evaluation, and (2) a viable method by culture for viable fungal propagules. The non-viable method led to ten spore morphotypes being found from related fungal sources. A total of 4401.88spores/m 3 and 32135.18 inert suspended particles/m 3 were recorded. The viable method led to the finding of nine fungal taxa as viable spores that mostly belonged to anamorphic forms of Ascomycota, although the pigmented yeast Rhodotorula F.C. Harrison (Basidiomycota) was also found. A total count of 40,500fungal CFU/m 3 air was estimated for all the sites sampled. Both the non-viable and viable sampling methods were necessary to monitor the bio-aerosol load in the La Plata Herbarium. The indoor air of this institution seems to be reasonably adequate for the conservation of vascular plants due to the low indoor/outdoor index, low concentrations of air spores, and/or lack of indicators of moisture problems. Copyright © 2016 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.
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Preferencias de los huéspedes de hostels de la ciudad de La Plata
De la Cruz, Gastón Miguel
2013-01-01
La presente tesis tiene como objeto estudiar las preferencias de huéspedes de un grupo de hostels de la ciudad de La Plata, con el fin de determinar la existencia de una demanda que tenga como principal preferencia a un atributo de índole social. Para cumplir con este objetivo se utilizó la técnica estadística análisis conjunto (conjoint analysis en inglés) la cual obligó a descomponer el concepto hostel en seis (6) atributos, de los cuales tres (3) atributos entran en la definición de índole...
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Alvaro Sordo-Ward
2017-11-01
Full Text Available We identified and analysed droughts in the La Plata Basin (divided into seven sub-basins for the current period (1961–2005 and estimated their expected evolution under future climate projections for the periods 2011–2040, 2041–2070, and 2071–2099. Future climate projections were analysed from results of the Eta Regional Climate Model (grid resolution of approximately 10 km forced by the global climate model HadGEM2-ES over the La Plata basin, and considering a RCP4.5 emission scenario. Within each sub-basin, we particularly focused our drought analyses on croplands and grasslands, due to their economic relevance. The three-month Standardized Precipitation Evapotranspiration Index (SPEI3 was used for drought identification and characterization. Droughts were evaluated in terms of time (percentage of time from the total length of each climate scenario, space (percentage of total area, and severity (SPEI3 values of cells characterized by cropland and grassland for each sub-basin and climate scenario. Drought-severity–area–frequency curves were developed to quantitatively relate the frequency distribution of drought occurrence to drought severity and area. For the period 2011–2040, droughts dominate the northern sub-basins, whereas alternating wet and short dry periods dominate the southern sub-basins. Wet climate spread from south to north within the La Plata Basin as more distant future scenarios were analysed, due to both a greater number of wet periods and fewer droughts. The area of each sub-basin affected by drought in all climate scenarios was highly varied temporally and spatially. The likelihood of the occurrence of droughts differed significantly between the studied cover types in the Lower Paraguay sub-basin, being higher for cropland than for grassland. Mainly in the Upper Paraguay and in the Upper Paraná basins the climate projections for all scenarios showed an increase of moderate and severe droughts over large regions
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Cancho, L.
2004-06-01
Full Text Available Bioleaching of chalcopyrite using mesophilic microorganisms considerably improves in the presence of silver. However, the studies carried out with moderate thermophilic microorganisms do not show a significant improvement with regard to the use of mesophilic bacteria. The main objective of the present work has been to study the silver fixation on chalcopyrite at 35 and 45 °C and its influence on the microbiological attack. Different observations using SEM, EDS microanalysis and concentration profiles using electron microprobe have been carried out. The study of the different samples showed that silver fixation was more favourable at 35 °C than at 45 °C. In addition, bacterial action improved silver penetration through attack cracks.
La biolixiviación de la calcopirita con microorganismos mesófilos mejora considerablemente cuando se utiliza plata en el medio de reacción. Sin embargo, los estudios realizados con microorganismos termófilos moderados no muestran una mejora significativa con respecto a la utilización de bacterias mesófilas. El objetivo del presente trabajo ha sido el estudio de la fijación de plata sobre calcopirita a 35 y 45 °C y su influencia en el ataque microbiológico. Se han realizado observaciones con SEM, microanálisis por EDS y perfiles de concentración con microsonda electrónica. El estudio de las distintas muestras reveló que la fijación de la plata fue más favorable a 35 que a 45 °C y que la acción bacteriana favoreció la penetración de la plata a través de las grietas de ataque. -
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Lucía Mercedes Mauro
2012-12-01
Full Text Available El cambio tecnológico es central en una estrategia de desarrolloeconómico endógeno, y su abordaje exitoso por partede las empresas requiere de un entorno a partir del que sepromueva y acompañe dicho proceso. El objetivo del estudioes comprender, desde una óptica territorial, la conducta innovadorade empresas industriales. Para ello se analiza el caso decuatro PYMES en segmentos con alto potencial de crecimientoeconómico de la ciudad de Mar del Plata (Argentina en el períodopost-convertibilidad. Se concluye que estas empresas tienenun marcado perfil innovador, aún cuando no se encuentraconsolidado el sistema de innovación local, falta de personalcon las competencias necesarias para llevar adelante el cambiotecnológico, y se observan desconexiones entre el sectorpúblico y el privado. ABSTRACT Technological changes are paramount for an endogenous economicdevelopment programs, and require that companies developingit operate in an environment promoting and nurturing suchprograms. This study´s goal is to understand the innovation behaviorof industrial companies from a territorial point of view. To thatend we analyzed four SMEs operating, in a high economic growthsegment after the conversion period in Mar del Plata, Argentina.It was deduced that said companies possess an innovative profile(even despite the fact that the local innovation support system isnot fully consolidated, lack personnel with the appropriate knowledgeto pursue technological changes, and there are mismatchesbetween the private and public sectors.
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La ciudad y la corte como espacios de poder en Hispanoamérica. La plata colonial
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Bridikhina, Eugenia
2007-08-01
Full Text Available This article demostrates how the City of La Plata, headquarters of the Audiencia and the Archbishopric, became defined as the Provincial Court, the centre of courtesan life, and the ceremonial centre of the monarchy. Public ceremonies and etiquette served as an instrument for royal domination represented in the social hierarchy, which defined and limited the social mobility of protagonists in colonial society. Ruling class acceptance of norms of conduct identical to Royal Court, and a similar social hierarchy with similar norms allowed for the functioning of the competitive and antagonistic worlds of Charca´s society.
Este artículo pretende demostrar que la ciudad de La Plata, sede de la Audiencia y Arzobispado se definió como la Corte provincial, el centro de vida cortesana y el escenario ceremonial de la monarquía. Las ceremonias públicas y etiquetas que se realizaban en este espacio del poder servían como un instrumento de dominio real, representaban y reforzaban la jerarquía social, marcando el lugar que sus protagonistas tenían en sociedad colonial. La aceptación por las clases dirigentes de pautas de conducta y sociabilidad idénticas a los de la Corte Real, y de un modelo similar de diferenciación jerárquica, con sus normas y reglas hacía que funcionara el mundo competitivo y antagónico de la sociedad charqueña.
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Síntesis electroquímica de nanopartículas de plata en presencia de un surfactante neutro
Blandón, Lucas; Vázquez, Mario V.; Boannini, Elisa; Ballarin, Bárbara
2015-01-01
Muchas de las aplicaciones de las nanopartículas de platase encuentran en el área de la medicina como agentesantimicrobianos. Para evaluar la actividad antimicrobianade estos materiales, es importante garantizar que se encuentran estables y que los agentes estabilizantes seanbiocompatibles. Entre los métodos propuestos para lasíntesis de nanopartículas de plata se encuentran losmétodos electroquímicos, que han mostrado tener ventajasgracias a la facilidad para controlar las variables desíntes...
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Calcagno, Alberto; Yamashiki, Yosuke; Mugetti, Ana
2002-08-01
The La Plata River Basin is one of the largest international river basins in the world, with an area of about 3 million km2. It spreads across five countries (Argentina, Bolivia, Brazil, Paraguay and Uruguay), and its water resources are essential for their economic development. Together with reservoir development, extensive deforestation, intensive agriculture practices and large urban developments took place in the Paraná, Paraguay and Uruguay basins, affecting environmental conditions and raising important issues concerning water resources use and conservation. Therefore, the need to promote participatory and cooperative efforts among water resources stakeholders, as well as the systematic exchange of information and experiences on common regional problems among organizations and experts from throughout the basin who are devoted to water resources use and management, was reported by researchers and managers gathered at the First and Second International Workshops on Regional Approaches for Reservoir Development and Management in the La Plata River Basin (held in 1991 and 1994). As a concrete response to this need, the efforts of a number of organizations from various countries within the basin, with the support of international and national governmental organizations, resulted in the foundation of La Plata River Basin Environmental Research and Management Network (RIGA) in March 2001. This was within the framework of the Third International Workshop, which was precisely one of the short-term activities included in the RIGA Action Plan. During the preparatory processes for the RIGA Network, the presence of Japanese cooperation supporting the La Plata River Basin Workshops through a non-governmental international organization (ILEC) played an important role in stimulating such an organization-based joint approach in the basin. This outcome, although not originally planned, constituted a welcomed byproduct of its main specific interest in the region, which was the
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Pigeau, Nora; Barnes de Carlotto, Estela; Lovazzano, Eduardo; Velazco, Luis; Cuadra, Estela de la; Cardoso, Miriam
2014-01-01
Informe de Radio Universidad Nacional de La Plata sobre el hallazgo de la nieta número 115, recuperada por Abuelas de Plaza de Mayo: Ana Libertad Baratti de la Cuadra. El 22 de agosto de 2014 la ciudad de La Plata y el país entero celebró el encuentro de la nieta de la co-fundadora y primera presidenta de la Asociación Abuelas de Plaza de Mayo, Alicia “Licha” Zubasnabar de De la Cuadra: apareció Ana Libertad Baratti de la Cuadra. Héctor Carlos Baratti y de Elena de la Cuadra fueron se...
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Ramón I. Cieza
2012-01-01
Full Text Available Currently, family farming has taken visibility both in academic works and in the design of public policies. Even though are recognized own characteristics which differentiate it from the business production, they are presented according to the type of production and the territory where they are inserted, particularities that allow defining and analyzing them. In the case of family horticultural and flower production, which supplies with fresh products to big urban centers, the specificity of labor-intensive production system, the technologies utilized, the characteristics of the obtained products, their commercialization and their localization, differs substantially from others productive systems of the country. According to diagnosis made by INTA [2004] and other qualitative works in suburbs of Buenos Aires, the difficulties faced by these households are multiples. Among the most important are mentioned the subordination in the commercial chain and the access to financing. This paper seeks account for a territorial development project in the peri-urban region of Gran La Plata, which addresses from an integral perspective, to financing aspects and commercialization to family farmers It focuses on 30 family farmers from La Plata and Berazategui belonging to the project "Banco Social", implemented by Facultad de Ciencias Agrarias y Forestales from UNLP; advancing on an analysis regarding the access to financing and the commercial strategies carried out by the family farmers under studyEn la actualidad, la agricultura familiar ha tomado visibilidad tanto en trabajos académicos como en el diseño de políticas públicas. Si bien se reconocen características propias que la diferencian de la producción empresarial, se presentan de acuerdo al tipo de producción y el territorio donde se inserta, particularidades que permiten definirlas y analizarlas. En el caso de la producción hortiflorícola familiar que abastece de productos frescos a los
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MICAELA DE LUCÍA
Full Text Available RESUMEN El género Potamolithus Pilsbry, 1896 (Gastropoda; Tateidae, posee 31 especies, 22 de las cuales se hayan en la Argentina distribuidas principalmente en la cuenca Del Plata, definiendo al río Uruguay y al Río de la Plata como una zona caliente de diversidad en gasterópodos dulceacuícolas. Sin embargo, la mayoría de sus especies han sido descriptas solo por caracteres conquilógicos y, unas pocas tienen datos anatómicos, conllevando a la descripción de subespecies o morfos que se superponen unos a otros. A Potamolithus lapidum algunos autores le atribuyen cuatro subespecies (con datos conquiológicos, y una con datos parciales de anatomía blanda, sin embargo otros incluyen ocho “morfos”. Aquí nosotros damos un comienzo en el estudio de Potamolithus lapidum elevando a Potamolithus lapidum supersulcatus Pilsbry, 1896 a la categoría de especie, de la cual solo se conocen caracteres conquiológicos y radulares parcialmente. Aportamos datos de: concha, órganos paleales, cabeza, pie, pene, rádula, sistemas reproductor femenino y masculino, sistema nervioso y, secuencia parcial del gen mitocondrial citocromo c oxidasa subunidad I. Es necesario realizar una buena descripción de las especies del género Potamolithus debido a que algunas de las especies ya han sido citadas como especies vulnerables y que habitan ríos que están siendo modificados por la actividad humana y por la presencia del bivalvo invasor Limnoperna fortunei.
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Oyhenart, Evelia E; Torres, María F; Quintero, Fabián A; Luis, María A; Cesani, María F; Zucchi, Mariel; Orden, Alicia B
2007-09-01
To evaluate nutritional status and body composition as indicators of quality of life among poor children served by neighborhood soup kitchens in La Plata, Argentina. From April to November 2004, we conducted a cross-sectional study of 608 healthy children from 1-11 years of age who were being served by two neighborhood soup kitchens in the outlying areas of the city of La Plata. The sample was stratified by age and sex. Height-for-age, weight-for age, and weight-for-height, were measured, as well as BMI, muscle mass and adipose tissue. Z-scores were computed for the data. Odds ratios and the respective 95% confidence intervals were calculated. Prevalence of low weight-for-age was 9%; low weight-for-height, 3%; and low height-for-age, 15%. The prevalence of overweight and obesity were 12.5% and 7.1%, respectively. Among the study sample, 47.2% had low muscle mass and 20.4% had low adipose tissue. Among overweight and obese children, adipose tissue was 34.3% higher than that of the reference population, while muscle mass was 12.5% lower. Undernutrition and obesity are both found among the community of children studied. The high prevalence of delayed growth (i.e., low height-for-age), undernutrition (i.e., low weight-for-age), and the acute lack of muscle mass even among overweight and obese children, seem to be part of the consequences of an inevitable process that unfolds in the face of adverse living conditions.
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Evelia E. Oyhenart
2007-09-01
Full Text Available OBJETIVOS: Evaluar el estado nutricional y la composición corporal, como indicadores de la calidad de vida, en niños pobres que concurren a comedores comunitarios de La Plata, Argentina. MÉTODOS: Se realizó un estudio transversal entre abril y noviembre de 2004 con 608 niños y niñas sanos de 1 a 11 años de edad que asistían a dos comedores barriales ubicados en la periferia de la ciudad de La Plata, Argentina. La muestra se estratificó según la edad y el sexo de los participantes. Se determinó la talla para la edad, el peso para la edad y el peso para la talla, así como el índice de masa corporal, el área muscular y el área adiposa. Los datos se transformaron a puntuaciones z. Se calcularon la razón de posibilidades (odds ratio y sus respectivos intervalos de confianza de 95%. RESULTADOS: La prevalencia de peso bajo para la edad fue de 9,0%, la de peso bajo para la talla fue de 3,0% y la de talla baja para la edad de 15,0%. Las prevalencias de sobrepeso y obesidad fueron de 12,5% y 7,1%, respectivamente. En esta población, 47,2% presentó déficit de masa muscular y 20,4% tenía déficit de masa adiposa. En los niños con sobrepeso y obesidad, el área adiposa fue 34,3% mayor que la de la población de referencia; en contraste, el área muscular fue 12,5% menor. CONCLUSIONES: En las comunidades infantiles estudiadas coexisten la desnutrición y el sobrepeso. La elevada prevalencia de retraso en el crecimiento (talla baja para la edad y desnutrición global (peso bajo para la edad y la grave reducción de la masa muscular, aun en niños con sobrepeso u obesidad, parecen ser consecuencias de un proceso adaptativo inevitable frente a las condiciones adversas de vida.OBJECTIVES: To evaluate nutritional status and body composition as indicators of quality of life among poor children served by neighborhood soup kitchens in La Plata, Argentina. METHODS: From April to November 2004, we conducted a cross-sectional study of 608 healthy
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Girini, Juan Manuel; Palacio, Facundo Xavier; del Huerto, María del C.; Kuzmanich, Nicolás
2016-01-01
El Estornino Pinto (Sturnus vulgaris) es un ave introducida en Argentina que establece dormideros comunales durante la época no reproductiva. A pesar de ser una de las especies invasoras más perjudiciales del mundo, se conoce muy poco acerca de su ecología en Argentina. En este trabajo se caracterizaron los dormideros comunales del Estornino Pinto en la ciudad de La Plata con el objetivo de evaluar la selección del sitio de dormidero por parte de la especie. Se encontró un total de 34 dormide...
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Girini, Juan M; Palacio, Facundo X; del Huerto, María del C; Kuzmanich, Nicolás
2014-01-01
El Estornino Pinto (Sturnus vulgaris) es un ave introducida en Argentina que establece dormideros comunales durante la época no reproductiva. A pesar de ser una de las especies invasoras más perjudiciales del mundo, se conoce muy poco acerca de su ecología en Argentina. En este trabajo se caracterizaron los dormideros comunales del Estornino Pinto en la ciudad de La Plata con el objetivo de evaluar la selección del sitio de dormidero por parte de la especie. Se encontró un total de 34 dormide...
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Sistemas de calidad en turismo. Posibilidades y restricciones de su implementación en Mar del Plata
Castellucci, Daniela I.
2011-01-01
La tesis tiene como objetivos indagar en las empresas hoteleras, gastronómicas y de balnearios de la ciudad de Mar del Plata (Argentina), el nivel en que se encuentra su cultura de la calidad; e identificar cuáles son los factores determinantes en la toma de decisión para la implementación de Sistemas de Gestión de Calidad. Desde un enfoque cualitativo, y tomando la modalidad de estudio de casos múltiples, se analizan en dieciocho empresas de servicios turísticos, la cultura organizacional, d...
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Evaluación "In vitro" e "in vivo" de la seguridad de nanopartículas de plata
Ávalos Fúnez, Alicia
2017-01-01
El rápido desarrollo de la nanotecnología ha abierto la puerta a la obtención de productos y aplicaciones innovadoras para una amplia gama de sectores de la industria y el consumo. Se estima que de todos los nanomateriales utilizados en productos para el consumo, las nanopartículas de plata (AgNPs) son las que tienen un mayor grado de comercialización. Sin embargo, a pesar de las innumerables aplicaciones que presentan, poco se sabe sobre su toxicidad, planteando un riesgo para la salud human...
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Construcción de un edificio bajo la figura del fideicomiso en Mar del Plata, en 2008
Fagioli, Francisco
2008-01-01
Se desarrolló el caso particular de la construcción de un edificio de departamentos en la ciudad de Mar del Plata proponiendo la implementación de la figura del Fideicomiso y se analizaron las ventajas que ello representa para los Fiduciantes. El proyecto incluyó un análisis del mercado y comercialización de los servicios, la viabilidad técnica y la de gestión, la enumeración de inversiones y los requisitos necesarios para cumplir con las legislaciones vigentes, el análisis ...
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V. Andresiuk
2007-12-01
Full Text Available The aim of this work is to analyze whether there is a seasonal prevalence of parasites in dog feces from public squares in Mar del Plata city, Argentina, and to evaluate the climatic conditions that promote the development of parasites and allow the transmission to people. The study was performed in 21 squares from June 2001 to May 2002. Samples were processed by the Willis technique. Differences in prevalence of parasites were examined for significance by the Chisquare test. Climatic data were obtained from the Library of the National Meteorological Service of Argentina. Total parasitic prevalence was higher in winter than in summer. The prevalence of Ancylostoma spp. was higher in the summer-autumn period. For Toxocara canis, the prevalence was higher in winter whereas for Trichuris vulpis, it was higher in winter, spring and summer. This work shows high prevalence of total parasites throughout the year. For Ancylostoma spp., summer and autumn might be the seasons with higher sanitary risk. On the other hand, T. canis could present the higher risk to people in winter and, T. vulpis, would be transmitted throughout the whole year. The seasonal variation in prevalence of dog parasites results in continuous exposure to people visiting the squares, not only Mar del Plata residents but also tourists from other regions of Argentina and the world, with at least one species of parasite with sanitary risk.El objetivo de este trabajo es analizar la variación estacional de la prevalencia de los parásitos presentes en las heces caninas halladas en plazas públicas de la ciudad de Mar del Plata y evaluar aquellas condiciones climáticas que promueven su desarrollo y permiten su transmisión a la gente. El estudio se realizó en 21 plazas desde junio de 2001 hasta mayo de 2002. Las muestras fueron procesadas con la técnica de Willis. Se utilizó el test de c² para comparar la prevalencia de los diferentes parásitos. Los datos climáticos fueron
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Rossello, Eduardo A.; Veroslavsky, Gerardo; de Santa Ana, Héctor; Rodríguez, Pablo
2018-04-01
An integrated study of geological and geophysical data of the Río de la Plata region and its relation to the evolution of the Atlantic passive margin is herein described. This characterization is based on the available geological and geophysical information and on the correlation of the southern end of the best-known Santa Lucía Basin in Uruguay to the Salado Basin in Argentina, and their connection through the Quilmes Trough. Furthermore, a new Meso-Cenozoic depocenter is characterized and identified as Recalada Trough, subparallely aligned to the Quilmes Trough and separated from it by the Magdalena-Montevideo High. Both sedimentary fillings present ENE-WSW trending main axes and reach an average thickness of almost 2000 m. This suggests an evolution from a triple junction where interconnected extensional arms developed, which have had common Mesozoic tectosedimentary histories related to the early opening of the Atlantic Ocean. Based on the geophysical and geological evidence, the previously accepted existence in the Río de la Plata of a first-order structural feature along the international border between Argentina and Uruguay, associated to an ENE-WSW trending tectonic high, identified as Martín García, is unjustified. The tectonic evolution of the Atlantic margin in front of the Río de la Plata estuary is the consequence of a long deformation history starting in the Precambrian up to recent times. Each Precambrian, Paleozoic, Mesozoic and Cenozoic tectonic scenario adds different weak trends on the continental crust, which control the evolution of the sedimentary depocenters. The presence of these tectosedimentary records influence the bathymetric control of the Río de la Plata and the dynamics of the recent estuarine deposits. The Meso-Cenozoic sedimentary infill is estimated to comprise considerable ranges of sandstones and conglomerates associated with faulted blocks of the crystalline basement, with expected petrophysical conditions oscillating in
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Milla González, Miguel
2015-01-01
Se estudia como influye la variación del pH en la solubilidad de una sal cuya parte aniónica es una base débil. Es el caso del acetato de plata. Mediante una animación se muestra el desplazamiento del equilibrio hacia una mayor solubilización. El paso siguiente es encontrar una expresión sencilla que relaciona la solubilidad con el pH y se representa gráficamente dicha función mediante una hoja de cálculo.
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Educación literaria en las novelas de colegios de la "Edad De Plata"
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Fermín Ezpeleta Aguilar
2013-12-01
Full Text Available En un periodo histórico de proliferación de colegios religiosos como es la "Edad de Plata" se consolida en la literatura española el subgénero narrativo de novelas de internado docente. El cotejo de este corpus novelístico aporta claves de investigación acerca de la educación literaria de los escritores y de las generaciones de estudiantes bachilleres de la Restauración, puesto que refleja prácticas de lectura y de escritura, actividades teatrales y canon de lecturas, en un contexto en el que la didáctica de la literatura observa una progresiva sustitución del método retórico por el historicista.
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Mario Bunge en la Universidad Nacional de La Plata : Breve testimonio de su visita en el año 2000
Bunge, Mario
2000-01-01
Radio Universidad Nacional de La Plata registra un breve testimonio del Dr. Mario Bunge en su visita a la UNLP en el año 2000. Resalta su paso por esta Universidad, así como las características de la misma. Mario Augusto Bunge: nació en Buenos Aires el 21 de septiembre de 1919. Físico y filósofo, se graduó en la UNLP en 1952. Reside en Montreal (Canadá).
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Susana L. Paradell
2010-06-01
Full Text Available En la presente contribución, se realizó un relevamiento de los ejemplares tipo de Cicadellidae, depositados en la colección de la División Entomología del Museo de La Plata (MLP. Fueron examinados y listados 86 ejemplares tipo pertenecientes a 32 especies: siete Cicadellinae y 25 Gyponinae, las que fueron descriptas por los siguientes autores: Berg, DeLong, DeLong & Freytag, DeLong & Martinson, Tesón, Spångberg y Young. Para cada ejemplar tipo se brinda información acerca del nombre específico, referencia bibliográfica, categoría de tipo y procedencia.
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Mendoza Aranzamendi, Jessica Aleida
2017-01-01
La presente investigación tuvo como objetivo analizar las condiciones de acceso a los servicios financieros y su influencia en el crecimiento de las Micro y Pequeñas Empresas peruanas que exportan joyería de plata. Las unidades de análisis son las Micro y Pequeñas Empresas que exportan joyería de plata. Se trata de una investigación relacional, de campo y comparativa (al comparar las tasas de crecimiento de estas MYPES con las que han obtenido las grandes empresas que pertenecen al sector exp...
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Plavan, A Acuña; Gurdek, R; Muñoz, N; Gutierrez, J M; Spósito, M; Correa, P; Caride, A
2017-01-01
The large estuaries can present long narrow branches called subestuaries or tidal creeks. These types of subsystems are distributed along the Uruguayan coast of the Río de la Plata estuary and are very important as nursery and refuge areas for fish. For the first time, the seasonal composition and abundance of the fish community of the Solís Chico subestuary was studied by using beach and gill nets. Fourteen species, mainly euryhaline (86%) presented a significant representation of juvenile stages. The fish community was dominated by Odontesthes argentinensis, Platanichthys platana, Mugil liza, Brevoortia aurea, Micropogonias furnieri and Paralichthys orbignyanus, similar to adjacent subestuaries. While Micropogonias furnieri and B. aurea were the most abundant species, some other species were rarely caught. A seasonal variation of the fish assemblage abundance was detected, with higher values in autumn showing a positive correlation with temperature. Species that complete their life cycle in the Río de la Plata estuary, some of which are relevant to fisheries (64% of the analyzed species) were captured in the Solís Chico subestuary. The importance of this environment as a transitional system for some estuarine fish species is advised.
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Marrero, Analía; Tudurí, Adriana; Pérez, Laura; Cuña, Caroline; Muniz, Pablo; Lopes Figueira, Rubens; Michaelovitch de Mahiques, Michel; Alves de Lima Ferreira, Paulo; Pittauerová, Daniela; Hanebuth, Till; García Rodríguez, Felipe
2014-12-01
El Río de la Plata (RdlP) presenta significativas variaciones naturales (hidrodinámicas y oceanográficas) asociadas a diferentes condiciones climáticas. El propósito de este trabajo es inferir los cambios de aportes continentales de sedimentos y su relación con las variaciones hidrológicas del Río de la Plata, a través del análisis de proxies sedimentológicos y geoquímicos en testigos de sedimentos de la plataforma interna uruguaya que registran los últimos 100 años, aproximadamente. A partir de la datación por 210Pb de dos testigos de sedimentos (GeoB 13813-4 y BAR1) se reconstruyó la geocronología del ambiente, y se relacionó con datos de las forzantes climáticas Pacific Decadal Oscillation, El Niño/La Niña Southern Oscillation, Atlantic Multidecadal Oscillation, y las anomalías hidrológicas de los ríos Paraná y Uruguay. Los valores más positivos y estables del Southern Oscillation Index, los cuales corresponden a fases La Niña, se observan en el periodo correspondiente entre 1910-1970, respecto al resto de la serie, donde se aprecia una mayor variabilidad y una tendencia hacia valores más negativos (eventos El Niño). Se hicieron dendrogramas (clustering) jerárquicos para ambos testigos. Para el testigo GeoB 13813-4, se utilizó la relación Ca/Ti y la granulometría, mientras que para BAR1 se recurrió a variables granulométricas y la tasa de sedimentación. El mayor aporte continental hacia la región de la plataforma adyacente al Río de la Plata registrado a partir del año 1970, podría ser el factor principal de los agrupamientos observados en los clusters para ambos testigos. Las agrupaciones mostraron una diferenciación en la década de 1970, lo que estaría asociado al aumento de los caudales de los ríos Paraná y Uruguay, durante las últimas tres décadas del siglo XX. Por otra parte se observa que la granulometría del testigo BAR1 presentó un mayor tamaño de grano y más variabilidad que en el caso del testigo Geo
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Massone, Héctor; Corleto, Bárbara; Albornoz, Daniel; Lima, Lourdes; Pertini, Ignacio; Damiano, Fernanda; Barilari, Agustina; Fresta, Paula
2016-01-01
La ciudad de Mar del Plata es la cabecera del Partido de General Pueyrredón, tiene una población de 620.000 habitantes y se abastece íntegramente del recurso hídrico subterráneo. Una parte importante del proceso de gestión de este recurso es la prevención de la contaminación; en este sentido, son variadas las metodologías de caracterización de carga contaminante; uno de sus aspectos es el modo de disposición, en el que pueden identificarse fuentes puntu...
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Herrera, Leandro Javier
2014-01-01
Año a año Argentina es elegida como sede de todo tipo de reuniones, una modalidad turística vista como una actividad económica rentable que crece sostenidamente a nivel mundial y nacional. El siguiente trabajo de investigación describe la situación actual de La Plata como ciudad sede de este fenómeno, los diferentes eventos realizados durante el año 2013 y características generales del consumidor principal de este segmento. Se realiza una conceptualización y contextualización del turism...
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Las localidades menores del sur de Mar del Plata desde una perspectiva demogeográfica (1991-2001
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Sofía Estela Ares
2008-01-01
Full Text Available En relación con el crecimiento demográfico de las localidades ubicadas al sur de Mar del Plata (Partido de General Pueyrredon el problema es establecer el aporte de los saldos vegetativos y de los saldos migratorios. Las bases de datos censales permiten la aproximación indirecta al comportamiento vegetativo; con respecto a las migraciones, no es posible calcular saldos de movilidad. Los resultados se obtuvieron mediante el procesamiento cuantitativo de datos censales y muestran un proceso de envejecimiento en las localidades mencionadas y la probable preeminencia del componente migratorio en el crecimiento demográfico.
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Updates since Brown v. Plata: alternative solutions for prison overcrowding in California.
Horne, Christopher; Newman, William J
2015-03-01
With the number of inmates under the care of the California Department of Corrections and Rehabilitation (CDCR) swelling over the past few decades, California faces a challenge. The U.S. Supreme Court ruled in their 2011 decision in Brown v. Plata that overcrowding violates inmates' Eighth Amendment rights, specifically that they are denied adequate medical and mental health care. Federally mandated release programs have historically raised some concerns regarding public safety and fiscal efficiency. Given the large number of mentally ill inmates in the United States, alternatives such as assisted outpatient treatment, mental health courts, and increased funding for substance use treatment can be used proactively to reduce the CDCR population and provide long-term solutions to the overcrowding problem. These alternatives have already shown long-term cost savings in addition to reducing the recidivism of individuals involved and would help provide appropriate diversion for mentally ill individuals. © 2015 American Academy of Psychiatry and the Law.
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Directory of Open Access Journals (Sweden)
Rangel Ch. Orlando
1986-06-01
Full Text Available This contribution presents the plant-communities characterized in the trayect between La Plata (Huila and the crater of the Puracé volcano. The methodology followed in this study is that proposed in the Zurich-Montpellier school (BRAUN-BLANQUET, 1979. The profile of vegetation includs plant-communities of the jungle-type which are pluri-stratified on Ecuatorial and sub-Andean life zones and plantcommunities with a single stratification (upper Paramo belt. In the characterization of the plant-communities described was taken of the physiognomy (the structure as an expression of abiotic conditions. Dates about plant-density in the arboreal stratum and preliminary characteristics of the soil in some of the places inventaried also are provided.En esta contribución se caracterizan las comunidades vegetales que se establecen en el trayecto entre La Plata (Huila y el cráter del volcán Puracé. La metodología que se siguió es la de la escuela Zurich-Montpellier (BRAUN-BLANQUET, 1979. El perfil de vegetación incluye comunidades de tipo selvático pluriestratificadas, en las regiones de vida Ecuatorial y sub-Andina y comunidades uniestratificadas en la franja del super-páramo. Se colocó especial énfasis en el aspecto estructural (fisionomía de la vegetación y con base en los resultados obtenidos se recomiendan límites para la distribución de los estratos o arreglo en sentido vertical dentro de una fitocenosis determinada. Se suministran también datos sobre la densidad en los estratos altos y sobre las características preliminares de los suelos en algunos de los sitios muestreados.
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International Nuclear Information System (INIS)
Martinez, S.
1998-01-01
The first Uruguayan geological and pale ontological manuscript, al thought published later, is the Memorial geological about recent formation of Rio de la Plata deduced from their shell fossils, written by Damaso Antonio Larranaga, probably in 1819.This opus is commended here. (author)
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El sudor del sol y las lágrimas de la luna : la metalurgia del oro y de la plata en el antiguo Perú
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Cruz García de la Torre
1999-01-01
Full Text Available El oro y la plata fueron los metales cuyo hallazgo en el continente americano despertó grandes espectativas de riqueza en la menta de los primeros conquistadores, incluso antes de su descubrimiento. Los cronistas aportan abundantes noticias no sólo sobre las fabulosas riquezas metálicas que poseía el Perú sino, incluso, sobre los diferentes procesos tecnológicos que tuvieron lugar desde la extracción de ambos metales hasta su transformación en objetos suntuarios, así como sobre el valor y significado que tuvieron el oro y la plata en el Perú prehispánico.The finding of gold and silver in the american continent raised great expectations of wealth among the conquerors. The chronicles provide a detailed account not only of the fabulous richness in metals of Peru, but also of the technological process of extraction and of the transformation of these metals in luxury objects. Through them we learn about the simbolic meaning of gold and silver in prehispanic Peru.
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Watanabe, M; Ortega, E; Bergier, I; Silva, J S V
2012-08-01
The increasing human demand for food, raw material and energy has radically modified both the landscape and biogeochemical cycles in many river basins in the world. The interference of human activities on the Biosphere is so significant that it has doubled the amount of reactive nitrogen due to industrial fertiliser production (Haber-Bosch), fossil fuel burning and land-use change over the last century. In this context, the Brazilian La Plata Basin contributes to the alteration of the nitrogen cycle in South America because of its huge agricultural and grazing area that meets the demands of its large urban centres - Sao Paulo, for instance - and also external markets abroad. In this paper, we estimate the current inputs and outputs of anthropogenic nitrogen (in kg N.km(-2).yr(-1)) in the basin. In the results, we observe that soybean plays a very important role in the Brazilian La Plata, since it contributes with an annual entrance of about 1.8 TgN due to biological nitrogen fixation. Moreover, our estimate indicates that the export of soybean products accounts for roughly 1.0 TgN which is greater than the annual nitrogen riverine exports from Brazilian Parana, Paraguay and Uruguay rivers together. Complimentarily, we built future scenarios representing changes in the nitrogen cycle profile considering two scenarios of climate change for 2070-2100 (based on IPCC's A2 and B2) that will affect land-use, nitrogen inputs, and loss of such nutrients in the basin. Finally, we discuss how both scenarios will affect human well-being since there is a connection between nitrogen cycle and ecosystem services that affect local and global populations, such as food and fibre production and climate regulation.
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Directory of Open Access Journals (Sweden)
M Watanabe
Full Text Available The increasing human demand for food, raw material and energy has radically modified both the landscape and biogeochemical cycles in many river basins in the world. The interference of human activities on the Biosphere is so significant that it has doubled the amount of reactive nitrogen due to industrial fertiliser production (Haber-Bosch, fossil fuel burning and land-use change over the last century. In this context, the Brazilian La Plata Basin contributes to the alteration of the nitrogen cycle in South America because of its huge agricultural and grazing area that meets the demands of its large urban centres - Sao Paulo, for instance - and also external markets abroad. In this paper, we estimate the current inputs and outputs of anthropogenic nitrogen (in kg N.km-2.yr-1 in the basin. In the results, we observe that soybean plays a very important role in the Brazilian La Plata, since it contributes with an annual entrance of about 1.8 TgN due to biological nitrogen fixation. Moreover, our estimate indicates that the export of soybean products accounts for roughly 1.0 TgN which is greater than the annual nitrogen riverine exports from Brazilian Parana, Paraguay and Uruguay rivers together. Complimentarily, we built future scenarios representing changes in the nitrogen cycle profile considering two scenarios of climate change for 2070-2100 (based on IPCC's A2 and B2 that will affect land-use, nitrogen inputs, and loss of such nutrients in the basin. Finally, we discuss how both scenarios will affect human well-being since there is a connection between nitrogen cycle and ecosystem services that affect local and global populations, such as food and fibre production and climate regulation.
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Caneva, Hernán Andrés
2012-01-01
En el presente trabajo se expondrán los avances de un estudio exploratorio de corte cualitativo que estoy realizando con motivo de finalizar mi tesina de grado en la carrera de Lic. Sociología. En dicho estudio me propongo conocer y analizar representaciones acerca del aborto de jóvenes (varones y mujeres) escolarizados de sectores pobres de la ciudad de La Plata durante 2012. La hipótesis de trabajo que orienta el estudio indica que la integración en espacios de socialización tales como l...
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Oliveros Gómez, Honorio
2011-01-01
Se desarrolló a nivel de laboratorio una metodología de extracción de los metales preciosos oro, plata y del grupo del platino (platino, paladio, iridio y rodio) presentes en desechos electrónicos. Para determinarla, se indagó el estado del arte en la recuperación de metales a partir de desechos electrónicos, se desensamblaron componentes electrónicos, se caracterizó el material electrónico mediante técnicas analíticas de microscopia electrónica de barrido “Scanning electron microscope” SEM, ...
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Julieta Constanza Frediani
2006-01-01
Full Text Available In the last decade several studies done on the transformation of the city from compact to more scattered and fragmented have shown the concern for the effects the open and scattered city may have upon the environment. Although we consider that the urban models, "compact" and "diffuse", actually cannot be found in isolation, they are used to represent the extremes that relate the model of our city with these two models. The purpose of the present paper is to recognize in La Plata District, the behavioral pattern variable that causes the territorial conflicts in each of the models.
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International Nuclear Information System (INIS)
Colombo, J.C.; Barreda, A.; Bilos, C.; Cappelletti, N.; Migoya, M.C.; Skorupka, C.
2005-01-01
The 6-month assessment of the oil spill impact in the Rio de la Plata described in the preceding paper [Colombo, J.C., Barreda, A., Bilos, C., Cappelletti, N., Demichelis, S., Lombardi, P., Migoya, M.C., Skorupka, C., Suarez, G., 2004. Oil spill in the Rio de la Plata estuary, Argentina: 1 - biogeochemical assessment of waters, sediments, soils and biota. Environmental Pollution] was followed by a 13- and 42-month campaigns to evaluate the progress of hydrocarbon decay. Average sediment hydrocarbon concentrations in each sampling include high variability (85-260%) due to contrasting site conditions, but reflect a significant overall decrease after 3 years of the spill: 17 ± 27, 18 ± 39 to 0.54 ± 1.4 μg g -1 for aliphatics; 0.44 ± 0.49, 0.99 ± 1.6 to 0.04 ± 0.03 μg g -1 for aromatics at 6, 13 and 42 months, respectively. Average soil hydrocarbon levels are 100-1000 times higher and less variable (61-169%) than sediment values, but display a clear attenuation: 3678 ± 2369, 1880 ± 1141 to 6.0 ± 10 μg g -1 for aliphatics and 38 ± 26, 49 ± 32 to 0.06 ± 0.04 μg g -1 for aromatics. Hydrocarbon concentrations modeled to first-order rate equations yield average rate constants of total loss (biotic + abiotic) twice as higher in soils (k = 0.18-0.19 month -1 ) relative to sediments (0.08-0.10 month -1 ). Individual aliphatic rate constants decrease with increasing molecular weight from 0.21 ± 0.07 month -1 for isoprenoids and -1 for >n-C27, similar to hopanes (0.10 ± 0.05 month -1 ). Aromatics disappearance rates were more homogeneous with higher values for methylated relative to unsubstituted species (0.17 ± 0.05 vs. 0.12 ± 0.05 months -1 ). Continued hydrocarbon inputs, either from biogenic (algal n-C15,17; vascular plant n-C27,29) or combustion related sources (fluoranthene and pyrene), appear to contribute to reduced disappearance rate. According to the different loss rates, hydrocarbons showed clear compositional changes from 6-13 to 42 months
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Santiago Brizuela
2015-05-01
Full Text Available In this study, we describe two fossil remains of squamate reptiles found in Middle Pleistocene outcrops at the northern marine cliffs of the city of Mar del Plata (Buenos Aires province. The specimens were found forming a taphocenosis with remains of other microvertebrates (amphibians, mammals and birds. The reptiles recognized in the association are represented by remains of an undetermined colubrid, and the anguid Ophiodes sp. This latter finding represents the first fossil record for the family Anguidae exhumed in Argentina.
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Ornela Boix
2017-01-01
Full Text Available Este trabajo examina el problema de las identificaciones musicales a partir de una aproximación etnográfica a la música indie de la ciudad argentina de La Plata, basada en observaciones y entrevistas con un grupo de sellos musicales. Realiza una revisión crítica de la literatura que asume un enfoque narrativo y entiende el indie como género musical asociado a la juventud de las clases medias. En este contexto, el artículo interroga los enfoques subculturalistas, donde el indie es un ethos o una actitud, y las perspectivas bourdieanas, para las cuales el indie es un recurso de distinción. El artículo muestra las limitaciones de es tos análisis y propone una relación de intersección entre la crítica contemporánea del concepto de identidad y una perspectiva sensible a las vinculaciones involucradas en la producción de música. Así, el artículo describe al indie de la ciudad de La Plata en sus vinculaciones específicas: con la universidad, con los lugares de performance, con las nuevas tecnologías, con la ciudad, con los instrumentos musicales. Para concluir, afirma que estos elementos deben incorporarse al estudio de las identificacione s musicales.
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Directory of Open Access Journals (Sweden)
Nayla Pis Diez
2016-07-01
Full Text Available In this paper we intend to approach the events that marked the institutional and political dynamics of the Universidad Nacional de La Plata (UNLP between the months of September 1955 and May 1956, with special emphasis on the student movement. We'll use written sources as documentary material to revisit the first months of the postperonist UNLP, taking into account three aspects of the ongoing process: in the first place, the process of reconstruction and desperonización of university structures, teachers and administration. In second place, we explore which was the role of the student movement: what actions it carried out, which were the internal differences and the main debates. As is known, the process of university normalization went through a disruptive moment beginning 1956: the enactment of the decree-law no. 6.403, and in particular its article no. 28, would cause massive mobilizations (both in its favor and against, numerous outlets and even strong incidents in La Plata streets. The last lines of the work will be devoted to this third aspect of the indicated period
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Human toxocarosis. Its seroprevalence in the City of La Plata
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NE Radman
2000-06-01
Full Text Available Toxocara canis is very common in dogs throughout the world. It is the primary cause of visceral larva migrans (VLM in humans. Soil contaminated with T. canis embryonated eggs is the main source of infection of man. Our objective was to describe Toxocara seroprevalence in humans in the city of La Plata associated with some determinants such asage, presence or absence of clinical manifestations and risk factors. Blood samples were collected at random from 156 patients of different sex and age, with and without clinical symptoms compatible with the disease. The diagnostic technique ELISA test was performed with the Bordier Affinity Products Commercial Kit, using excretory-secretory Toxocara antigen with a sensitivity higher than 90%. The values were positive in 39% of the studied population. In the analysis according to age, the younger group presented significant differences with respect to the older one (Chi-square p<0.05. Positive patients presented clinical symptoms compatible with the disease (84%, and 41% presented some risk factor. The level of positivity obtained indicates a certain risk of being infectes mainly in patients younger than 15 years old. The authors agree that an early identification and treatment of VLM may save a life.
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Castilla, Mar??a Victoria
2008-01-01
El objetivo del texto es analizar las formas en que se reflejan los cambios sociales vinculados con la modernidad "tard??a" en las experiencias de las madres, tomando como caso a la ciudad de La Plata, Argentina. Para ello, se realizaron 30 entrevistas en profundidad a madres de dos generacionales (1970 y 2000) de nivel socioecon??mico medio. Dentro de los principales hallazgos, se menciona la persistencia de un modelo tradicional de distribuci??n de los roles, con rasgos de crianza modernos ...
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SÍNTESIS IN SITU DE NANOPARTÍCULAS DE PLATA SOBRE FIBRAS DE FIQUE
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Sergio Ovalle
2014-07-01
Full Text Available Se realizó la síntesis de un material nanocompuesto mediante la deposiciónin situ de nanopartículas (NPs de plata sobre fibras de Fique. La influencia de parámetros experimentales, como concentración del precursor, concentración del agente reductor y tiempos de inmersión de las fibras en la solución del precursor y del agente reductor, se evaluó en términos de recubrimiento, tamaño y dispersión del nanomaterial sobre la superficie. Los nanocompositos fueron caracterizados mediante espectroscopia de reflectancia difusa UV-Vis (RD, microscopía electrónica (FESEM y difracción de rayos X (DRX. El control de los parámetros experimentales mencionados permitió obtener un material que exhibe recubrimiento uniforme y completo de NPs sobre la superficie y tamaños promedio de NPs de 40 nm.
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Energy Technology Data Exchange (ETDEWEB)
Salamanca Grosso, G. [Departamento de Quimica, Instituto de Ciencias, Universidad de Tolima, Tolima (Colombia)
1996-06-01
New devices in analytical chemistry, has been emerged, and new procedures take great interest. The use of electrodes ion selective are very important in water and wastewater control of Ag+/S= electrodes for control process in wastewater from UASE plan pilot, before check their potentiometric performance so: 28.6+- 0.4 mV/decade, optimal time 20 seconds, and pH>10, detection limit 1.8 x 10``-6. The study was made in comparative way with yodometrical method: we check quantification by addition, subtraction an GRANT`s titrimetric. (Author) 10 refs.
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International Nuclear Information System (INIS)
Colombo, J.C.; Barreda, A.; Bilos, C.; Cappelletti, N.; Demichelis, S.; Lombardi, P.; Migoya, M.C.; Skorupka, C.; Suarez, G.
2005-01-01
Aliphatic (ALI) and aromatic (ARO) hydrocarbon concentrations, composition and sources were evaluated in waters, sediments, soils and biota to assess the impact of ∼1000 tons of oil spilled in Rio de la Plata coastal waters. Total ALI levels ranged from 0.4-262 μg/l in waters, 0.01-87 μg/g in sediments, 5-39 μg/g in bivalves, 12-323 μg/g in macrophytes to 948-5187 μg/g in soils. ARO varied from non-detected 10 μg/l, 0.01-1.3 μg/g, 1.0-16 μg/g, 0.5-6.9 μg/g to 22-67 μg/g, respectively. Offshore (1, 5, 15 km) waters and sediments were little affected and contained low background hydrocarbon levels reflecting an effective wind-driven transport of the slick to the coast. Six months after the spill, coastal waters, sediments, soils and biota still presented very high levels exceeding baseline concentrations by 1-3 orders of magnitude. UCM/resolved aliphatic ratio showed a clear trend of increasing decay: coastal waters (3.3) n-C23) and petrogenic/pyrogenic relationship (methylated/unsubstitued PAH) discriminated the samples according to the different degree of impact. The following paper present the results of the study of the progress of hydrocarbon disappearance in sediments and soils 13 and 42 months after the spill. - The Oil spill impact the Rio de la Plata was evaluated by HRGC and multivariate techniques applied to waters, sediments and biota
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Energy Technology Data Exchange (ETDEWEB)
Musslewhite, B.D.; Buchanan, B.A.; Ramsey, T.C.; Hamilton, J.S.; Luther, J. [Buchanan Consultants Ltd., Farmington, NM (United States)
2001-07-01
Biodiversity has increasingly become an important issue in determining the success of reclaimed minelands. The post-mine land-use of La Plata Mine is wildlife habitat, primarily for ungulates and small mammals. A reclamation plan was developed to promote biodiversity of reclaimed lands through the use of variable soil substrates, landscape features, and targeted seed mixes. A GIS was used to delineate the post-mine final surface contour into eight slope classes and eight aspect classes. The class information was used to develop four reclamation land types: 1. Upland shrub - north aspects, 2. Upland shrub - south aspects, 3. Grassland, and 4. Drainage. These land types correspond to four reclamation vegetation types. Suitable spoil materials and coarse textured topsoil materials were targeted for use on strongly sloping areas to minimize soil loss. Finer textured topsoil materials were targeted for the grassland and drainage types. The replacement depth of topsoil and topsoil substitute materials was varied for the reclamation vegetation types. Pre-mine vegetation inventories were used to develop unique seed mixes specific to physical habitat conditions exhibited by each land-type. Research conducted at La Plata Mine found that topsoil replacement thickness less than 15 cm promotes shrub establishment and topsoil thickness greater than 30 cm promotes native grass species. Therefore, areas designated for shrub communities will receive an average of 10 cm of topsoil or topsoil substitute material and the areas designated for grassland and drainage type communities will receive a minimum of 40 cm of topsoil. 12 refs., 1 fig., 1 tab.
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On the use of MODIS and TRMM products to simulate hydrological processes in the La Plata Basin
Saavedra Valeriano, O. C.; Koike, T.; Berbery, E. H.
2009-12-01
La Plata basin is targeted to establish a distributed water-energy balance model using NASA and JAXA satellite products to estimate fluxes like the river discharge at sub-basin scales. The coupled model is called the Water and Energy Budget-based Distributed Hydrological Model (WEB-DHM), already tested with success in the Little Washita basin, Oklahoma, and the upper Tone River in Japan. The model demonstrated the ability to reproduce point-scale energy fluxes, CO2 flux, and river discharges. Moreover, the model showed the ability to predict the basin-scale surface soil moisture evolution in a spatially distributed fashion. In the context of the La Plata Basin, the first step was to set-up the water balance component of the distributed hydrological model of the entire basin using available global geographical data sets. The geomorphology of the basin was extracted using 1-km DEM resolution (obtained from EROS, Hydro 1K). The total delineated watershed reached 3.246 millions km2, identifying 145 sub-basins with a computing grid of 10-km. The distribution of land cover, land surface temperature, LAI and FPAR were obtained from MODIS products. In a first instance, the model was forced by gridded rainfall from the Climate Prediction Center (derived from available rain gauges) and satellite precipitation from TRMM 3B42 (NASA & JAXA). The simulated river discharge using both sources of data was compared and the overall low flow and normal peaks were identified. It was found that the extreme peaks tend to be overestimated when using TRMM 3B42. However, TRMM data allows tracking rainfall patterns which might be missed by the sparse distribution of rain gauges over some areas of the basin.
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La intervención anglo-francesa en el Río de la Plata entre 1847 y 1851. Un intento frustrado
Jaime Collazo Odriozola
2007-01-01
En la quinta década del siglo XIX, Gran Bretaña y Francia intervinieron en el conflicto entre los bandos políticos hegemónicos en el Río de la Plata, asumiendo la defensa del gobierno de Montevideo, recluido en los límites de la ciudad. El enfrentamiento era con los federales, particularmente con el gobierno de la ciudad de Buenos Aires y los encargados de las Relaciones Exteriores de las provincias argentinas, encabezado por Juan Manuel de Rosas, quizá la figura más controvertida en la histo...
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Contribución a la identificación de esporas del Reino Fungi en la atmósfera de La Plata, Argentina
Nitiu, Daniela S.; Mallo, Andrea C.; Gardella Sambeth, María C.; Morbelli, Marta A.
2010-01-01
Based on the aeromycological analysis of La Plata city, artificial Morphological Groups of fungal spores were defined. This study is a methodological contribution to the identification and counting of a fraction of the atmospheric micobiota. For the definition of groups, the criteria of Saccardo (1886) were taken into account and the groupings created by Díaz et al. (1998) and Aira et al. (2005) have been reformulated. Four new groups have been created and other sporal types have be...
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Fükelman, María Cristina; Ladaga, Silvia Andrea Cristian; Sánchez Pórfido, Elisabet
2012-01-01
Este trabajo se inscribe en los avances de la investigación, “Arte de acción en La Plata en el Siglo XXI. Registro e intervenciones artísticas”; acreditado por la Facultad de Bellas Artes, Secretaría de Ciencia y Técnica de la Universidad Nacional de La Plata, en el marco de Programas de Incentivos del Ministerio de Educación de la Nación. En este artículo se analizan las acciones de los colectivos Lanzallamas (conformado por estudiantes avanzados de la carrera de Sociología) y Arte al Ata...
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Directory of Open Access Journals (Sweden)
Susana L. PARADELL
2010-01-01
Full Text Available En la presente contribución, se realizó un relevamiento de los ejemplares tipo de Cicadellidae, depositados en la colección de la División Entomología del Museo de La Plata (MLP. Fueron examinados y listados 86 ejemplares tipo pertenecientes a 32 especies: siete Cicadellinae y 25 Gyponinae, las que fueron descriptas por los siguientes autores: Berg, DeLong, DeLong & Freytag, DeLong & Martinson, Spångberg , Tesón y Young. Para cada ejemplar tipo se brinda información acerca del nombre específico, referencia bibliográfica, categoría de tipo y procedencia.
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Directory of Open Access Journals (Sweden)
Neipp, C.
2000-08-01
Full Text Available One of the most interesting techniques for the production of holographic optical elements is silver halide sensitised gelatin (SHSG. It combines the high sensitivity of photographic emulsions with the well-known low scattering and high diffraction efficiencies corresponding to dichromated gelatin. In this work we made a comparative study on SHSG holograms recorded on three different red sensitive emulsions: Agfa 8E75 HD, Slavich PFG-01 and BB-640 . The influence of the degree of hardening of the gelatin and the size and concentration of silver halide grains in the SHSG proccess is studied. And we will show that real high diffraction efficiencies can be obtained when using BB-640 and Slavich PFG-01 plates for recording phase transmission holograms (as high as 93% for PFG-01 and 90% for BB-640, allowing for reflections. Our investigations reveal that PFG-01 and BB-640 emulsions are not only a substitution to Agfa material, but may offer better results at a moment in which Agfa has stopped its production of holographic material.
Una de las técnicas más interesantes para la obtención de elementos ópticos holográficos es la gelatina sensibilizada de haluro de plata (GSHP. Esta técnica combina la alta sensibilidad de las emulsiones fotográficas con los conocidos altos rendimientos en difracción y bajos niveles de scattering correspondientes a la gelatina dicromatada. En este trabajo se ha hecho un estudio comparativo sobre hologramas en gelatina sensibilizada de haluro de plata registrados en tres emulsiones diferentes sensibles al rojo: Agfa 8E75 HD, Slavich PFG-01 y BB-640. En dicho estudio se ha analizado la influencia del grado de endurecido de la gelatina y la concentración y el tamaño de los granos de haluro de plata en el procesado GHSP. Se obtuvieron rendimientos en difracción realmente altos cuando se utilizaron las placas BB-640 y Slavich PFG-01 para el registro de hologramas de fase por transmisión (tan altos como el 93 -
Less is more: bondades de lo breve en el Río de la Plata
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Julio Prieto
2014-06-01
Full Text Available Las famosas palabras del prólogo de El jardín de senderos que se bifurcan condensan una poética narrativa que no sólo podemos considerar emblemática de uno de los autores seminales del siglo XX –Jorge Luis Borges– sino que también informa una de las líneas de escritura más fructíferas de la literatura del Río de la Plata: aquella que cifra un decoro literario en la eficacia de la brevedad. En esa tradición se cuentan algunas de las obras más significativas de esa literatura, desde la microtextualidad de los prólogos, “resúmenes y comentarios” de Borges, a los relatos breves y viñetas humorísticas de Julio Cortázar, Cristina Peri Rossi, Luisa Valenzuela y Ana María Shua.
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Ornela Boix
2017-01-01
Este trabajo examina el problema de las identificaciones musicales a partir de una aproximación etnográfica a la música indie de la ciudad argentina de La Plata, basada en observaciones y entrevistas con un grupo de sellos musicales. Realiza una revisión crítica de la literatura que asume un enfoque narrativo y entiende el indie como género musical asociado a la juventud de las clases medias. En este contexto, el artículo interroga los enfo...
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A numerical study of the Plata River plume along the southeastern South American continental shelf
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Felipe M. Pimenta
2005-12-01
Full Text Available The Rio de la Plata, one of the largest rivers on Earth, discharges into the ocean waters from basin that covers a large area of South America. Its plume extends along northern Argentina, Uruguay, and southern Brazil shelves strongly influencing the ecosystems. In spite of this, little is known about the mechanisms that control it. Here we report results of simulations with POM carried out to investigate the roles of wind and river discharge in Plata plume dynamics. Different outflows were explored, including an average climatological value and magnitudes representative of La Niña and El Niño. Forcing the model with river discharge the average plume speed was directly related to the outflow intensity. The Plata northward extension varied from 850 to 1550 km and for average discharge a band of low salinity waters formed from the estuary up to 30ºN of South Brazilian Shelf. Upwelling and downwelling winds were applied after 130 days. The distribution of low salinity waters over the shelf was more sensitive to the wind direction than to the river outflow variability. Downwelling winds were very capable of advecting the low salinity signal downshelf. Upwelling winds were efficient in eroding the plume, which was basically detached from the coast by Ekman drift. Abnormal plume intrusions toward low latitudes may be a result of the original plume position coupled with events of persistent strong downwelling favorable winds.O Rio da Prata, um dos maiores rios da Terra, descarrega no oceano águas de uma bacia de drenagem que cobre uma ampla área da América do Sul. Sua pluma extende-se ao longo do norte da Argentina, Uruguay e sul do Brasil influenciando amplamente os ecossistemas costeiros. A despeito disso, pouco se sabe a respeito dos mecanismos que a controlam. Relatamos aqui simulações conduzidas com o modelo POM na investigação do papel dos ventos e da descarga fluvial na dinâmica da pluma do Prata. Descargas com valores médios climatol
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México en la Conferencia Económica Mundial de Londres: el Acuerdo de la Plata de 1933
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Fabián Herrera León
2010-12-01
Full Text Available Pese a que a finales del mes de julio de 1933 la Conferencia Económica de Londres fue prácticamente clausurada al entrar en receso, México y otros países productores o usuarios de plata llegaron allí mismo a un acuerdo que ayudaría a equilibrar el mercado de la plata y elevar su precio. Sobre esta base, la política estadunidense de rescate del metal blanco estimulada poco tiempo después, aceleró la recuperación. Como ya ha sido destacado por la historiografía económica, los beneficios que obtuvo México del Acuerdo de Londres y del programa platista estadunidense contribuyeron sustancialmente a la expansión de su sistema monetario y al fortalecimiento de su banco central en el marco de la crisis. Sin embargo, se ha pasado por alto la cuidadosa e interesante actividad preparatoria del país para pugnar por este tipo de medidas, omisión que ha sido la principal motivación del autor en la realización de este artículo.Although the London Economic Conference (1933 was called off sine die at the end of July, Mexico and other silver producing and consuming countries came to an agreement that made possible to stabilize and increase the rate of this precious metal. As economic historiography has already emphasized, the benefits obtained by Mexico with the London Silver Agreement in 1933 favored both monetary system expansion and Central Bank strengthening during the crisis. Yet, the remarkable and cautious preparatory activity that Mexico fulfills to reach that goal has been neglected. This lack of information has prevented us to entirely understand this economic phenomenon and has been the author's main motivation while doing this paper.
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Área de Arte y Salud del Hospital de Niños Sor María Ludovica de La Plata
Iriart Urruty, Andrea
2014-01-01
El Hospital de Niños “Sor María Ludovica” de la ciudad de La Plata, a partir de la firma de la disposición N° 940/13 por parte de la dirección del mismo, funciona el “Área de Arte y Salud” integrada por el Servicio Social, el Servicio de Salud Mental del Hospital, la Biblioteca Ambulante, el Taller de Plástica y Literatura y el Laboratorio de Arte que desarrolla el Grupo La Grieta. Esta área es un espacio institucional abocado a aunar criterios y conjugar inquietudes en torno al papel del ...
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Sandra Elena Murriello
2006-01-01
Resumo: Esta tese pretende ser uma contribução à compreensão do diálogo estabelecido nas instituições museais com seus múltiplos visitantes, o que vem permitindo a sobrevivência, quando não a transformação, e consolidação dos museus como espaços culturais valorizados socialmente. Em particular, analiso a relação estabelecida entre o público do Museo de La Plata (Província de Buenos Aires, Argentina) e suas exposições paleontológicas. Essas exposições e suas valiosas coleções são as mais procu...
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Aquatic habitat modifications in La Plata River basin, Patagonia and associated marine areas.
Mugetti, Ana Cristina; Calcagno, Alberto Tomás; Brieva, Carlos Alberto; Giangiobbe, María Silvia; Pagani, Andrea; Gonzalez, Silvia
2004-02-01
This paper describes the environmental characteristics and situation of aquatic habitats and communities in southern continental and maritime areas of southeastern South America (Patagonian Shelf GIWA Subregion), resulting from an overall assessment carried out within the framework of a GIWA project, mostly on the basis of publicly available data. The main focus of the analysis was on the current situation of transboundary water resources and anthropogenic impacts. In the inland waters, habitat and community modifications result, principally, from dams and reservoirs built in the main watercourses for hydroelectric power generation and other uses. The transformation of lotic environments into lentic ones have affected habitats and altered biotic communities. In the La Plata River basin, invasive exotic species have displaced native ones. Habitats in the ocean have been degraded, as their biodiversity becomes affected by overfishing and pollution. This article includes a discussion on the causal chain and the policy options elaborated for the Coastal Ecosystem of Buenos Aires province and the Argentinean-Uruguayan Common Fishing Zone, where fishing resources are shared by both countries.
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Game at the old age, stories of old men from Mar del Plata
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Débora Paola Di Domizio
2012-11-01
Full Text Available This text attempts to problematise the topic of game at the old age. The author used the description of an experiment conducted in the city of Mar del Plata in the context of teacher education and whose participants were senior citizens and students in fourth year of their course of studies in Teacher Education in Physical Education in the province. The theoretical framework is provided by the bibliography studied in a Game Theory Seminar attended by the author in her journey to achieve a postgraduate degree as Master in Body Education and by other studies relevant to gerontology. Furthermore, the data obtained through interviews in the fieldwork described here is the input needed to analyze both conceptualizations about old age and aging and the ideas and preconceptions about game in senior citizens. This data also allows the analysis of the games of yesterday and today and the multiplicity of meanings they acquire at the old age, from the voices of the protagonists of the experience
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Prospects of approach and characterization of Mar del Plata peri-urban, Argentina
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Rosana Ferraro
2013-10-01
Full Text Available In Latin America in general, and in Argentina in particular, city growth without prior planning results in the formation of highly complex peri-urban areas. The urban-rural analysis based on the traditional model of country-city dichotomy is not enough to explain the processes that occur in these cities. On the basis of prior studies conducted in the peri- urban of Mar del Plata, Argentina, this paper aims to : a characterize the peri-urban by studying its functions throughout history, b propose a rereading for its further analysis through the complex systems theoretical-methodological approach, and c describe the main areas that account for its special heterogeneity and complexity. From an integral viewpoint, and taking the physical, sociocultural, productive, urban- residential and digester subsystems into account, the analysis of the peri-urban allowed to define areas with differential characteristics. Such areas admit higher disintegration in more detailed scales, making it easy to understand their operation and their problems. In conclusion, the complex systems approach results appropriate to promote the development of management strategies in areas as heterogeneous as the peri-urban.
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Dogliotti, A.I.; Ruddick, K.; Guerrero, R.
2016-01-01
Spatio-temporal variability of turbidity in the Río de la Plata (RdP) estuary (Argentina) at seasonal and inter-annual timescales is analyzed from 15 years (2000–2014) of MODIS data and explained in terms of river discharges and the El Niño Southern Oscillation (ENSO). Satellite estimates were first validated using in situ turbidity measurements and then the time series of monthly averages were analyzed to assess the seasonal and inter-annual variability of turbidity. A strong seasonal variab...
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Julio A. Hurrell; Jeremías P. Puentes; Patricia M. Arenas
2017-01-01
Este trabajo incluye resultados parciales de una línea de investigación en Etnobotánica urbana, que estudia los conocimientos locales sobre las plantas, sus partes y productos derivados en la conurbación Buenos Aires-La Plata. Se incluyen productos de plantas medicinales de reciente ingreso en el área de estudio a través de inmigrantes oriundos de Paraguay. Los productos corresponden a 10 especies: Achyrocline alata(“jateí-ka’á”), Baccharis gaudichaudiana (“jaguareté-ka’á”), Cuphea lysimachio...
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La industria naval de la ciudad de Mar del Plata. Situación de las PyMEs y de las grandes empresas
Zini, José María
2013-01-01
El objetivo de este trabajo es brindar una descripción cualitativa de la problemática que hoy posen la pequeñas empresas del sector del Industria Naval en la ciudad de Mar del Plata en relación a los grandes grupos económicos que dominan la actividad pesquera y que afectan directamente al normal funcionamiento de estas PyMEs, teniendo en cuenta que denominamos Pymes a aquellas empresas que facturan anualmente hasta $15.000.000 y desde ese valor en adelante las llamamos Grandes Empresas. La in...
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Aborto, abandono, y la muerte de Augusta García Platas en Ayacucho, Perú, 1946
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Raúl Necochea López
Full Text Available Resumen Augusta García Platas murió tras un aborto clandestino en Ayacucho en 1946. Este ensayo, basado en materiales del Archivo Histórico de Ayacucho, da cuenta del proceso criminal que se abrió para determinar los responsables de su muerte. A pesar de que sindicaron a ciertos individuos como culpables directos de provocar el aborto, las autoridades judiciales consideraban que la causa de fondo de la muerte de la joven había sido el abandono por parte de quienes debían velar por su salud física y moral. Este caso nos brinda la oportunidad de esclarecer las estrategias que los implicados usaban para defenderse de acusaciones criminales. Además, nos ayuda a entender las diversas deficiencias del Poder Judicial peruano de mediados del siglo XX.
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Natural and human forcing in recent geomorphic change; case studies in the Rio de la Plata basin.
Bonachea, Jaime; Bruschi, Viola M; Hurtado, Martín A; Forte, Luis M; da Silva, Mario; Etcheverry, Ricardo; Cavallotto, José L; Dantas, Marcilene F; Pejon, Osni J; Zuquette, Lázaro V; Bezerra, Maria Angélica de O; Remondo, Juan; Rivas, Victoria; Gómez-Arozamena, José; Fernández, Gema; Cendrero, Antonio
2010-06-01
An analysis of geomorphic system's response to change in human and natural drivers in some areas within the Río de la Plata basin is presented. The aim is to determine whether an acceleration of geomorphic processes has taken place in recent years and, if so, to what extent it is due to natural (climate) or human (land-use) drivers. Study areas of different size, socio-economic and geomorphic conditions have been selected: the Río de la Plata estuary and three sub-basins within its watershed. Sediment cores were extracted and dated ((210)Pb) to determine sedimentation rates since the end of the 19th century. Rates were compared with time series on rainfall as well as human drivers such as population, GDP, livestock load, crop area, energy consumption or cement consumption, all of them related to human capacity to disturb land surface. Data on river discharge were also gathered. Results obtained indicate that sedimentation rates during the last century have remained essentially constant in a remote Andean basin, whereas they show important increases in the other two, particularly one located by the São Paulo metropolitan area. Rates in the estuary are somewhere in between. It appears that there is an intensification of denudation/sedimentation processes within the basin. Rainfall remained stable or varied very slightly during the period analysed and does not seem to explain increases of sedimentation rates observed. Human drivers, particularly those more directly related to capacity to disturb land surface (GDP, energy or cement consumption) show variations that suggest human forcing is a more likely explanation for the observed change in geomorphic processes. It appears that a marked increase in denudation, of a "technological" nature, is taking place in this basin and leading to an acceleration of sediment supply. This is coherent with similar increases observed in other regions. Copyright (c) 2010 Elsevier B.V. All rights reserved.
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Featherston, P L; Fernández, G; Munguía, H; Marín, M E
1998-01-01
Hospital San Juan de Dios and Sor María Ludovica in La Plata, between 1980 and 1997. Mucormicosis is a frequently fatal, opportunistic fungal infection, that affects immunocompromised patients. The risk factors include diabetes mellitus, leukemia, lymphoma, burns, etc. We present three cases of cutaneous mucormicosis in children 3, 10 and 11 years old, who had been sent to the hospital due to compound fractures in a car crash; one case of pulmonary mucormicosis in an adult 28 years old with prolonged corticotherapy and rhinocerebral mucormicosis in a patient 38 years old with a diagnosis of acute lymphoid leukemia.
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Otras voces de la Edad de Plata: Francisco Valdés, escritor y crítico literario
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Guadalupe Nieto Caballero
2017-02-01
Full Text Available El artículo estudia la prosa ensayística y aforística de Francisco Valdés, autor extremeño protagonista de la Edad de Plata. En sus textos, Valdés desarrolla una crítica que parte de la perspectiva de un lector atento, llegando a proponer, incluso, reinterpretaciones de las obras que glosa. De sus artículos en prensa se analizan su estilo y los autores que comenta, fuente indiscutible para conocer sus referentes y los caminos de su prosa. Se analizarán también algunos aspectos de su producción aforística a partir de un cuaderno inédito que enlaza perfectamente con la línea de la literatura de la época.
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International Nuclear Information System (INIS)
Di Gregorio, D.E.; Fernandez Niello, J.O.; Huck, H.; Somacal, H.; Curutchet, G.
2007-01-01
Concentrations of 21 Pb and 137 Cs in sediment samples collected from two cores at a drainage channel to the La Plata river estuary in Buenos Aires, Argentina, were measured using ultralow-background detection systems. The 21 Pb data were used to determine the rate of sediment accumulation of the sites. These results were correlated with some heavy metal (chromium and lead) concentrations of the samples in an attempt to characterize the historical input of contaminants due to the industrial development, which has taken place in this area over the last century. The 137 Cs measurements demonstrate that cesium dating is not adequate in regions of the southern hemisphere
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Santos, João O. S.; Chernicoff, Carlos J.; Zappettini, Eduardo O.; McNaughton, Neal J.; Greau, Y.
2017-12-01
The Río de la Plata Craton is one of the three major cratons of South America. The craton is largely covered by sedimentary basins where its most exposed area is Buenos Aires-Piedra Alta Province (Chernicoff et al., 2014). This province includes the Martín García Island in the confluence of Uruguay River and the Río de la Plata estuary. Despite to be a reference area for the craton the Martín García Island lacks modern geological investigation. We present U-Pb SIMS (secondary ion mass spectrometer) geochronological data on zircon and titanite, as well as Hf isotope determinations on zircon, from rocks of Martín García Island (Argentina), Sola and Dos Hermanas Islands (Uruguay) and from Paso Severino Formation (Uruguay). We investigated: 1) Rhyacian intermediate-to acidic plutonic, arc-type rocks of the Florida Belt dated between 2090 Ma and 2115 Ma, derived from juvenile Neoarchean crust (TDMHf: 2.52 Ga; average εHf: +3.62); 2) Rhyacian metadacite (San José metamorphic belt) of 2127 Ma; 3) Statherian metagabbros of 1724-1734 Ma, with Transplatense inheritance; 4) Early Ectasian metagabbro of 1392 Ma, with Rhyacian inheritance; and 5) Stenian metagabbros of 1193 Ma (TDMHf: 2.00 Ga, εHf: 0.1). Most of the dated orthogneisses show Brasilian-age (from 778 to 550 Ma) Pb loss in the zircons, interpreted to be caused by shearing or uplifting during Neoproterozoic. The results show that the area is not exclusively Rhyacian in age but encompasses Statherian, Ectasian, and Stenian gabbros. The last two are interpreted as distal intrusions associated to the Sunsás Orogen. All post-Transplatense metagabbros have geochemical signature of island arc basalt derived from primitive mantle with enrichment of LILE and depletion of HFSE. These characteristics point to the recurrence of magma chambers intermittently active during the Rhyacian, Statherian, Ectasian, and Stenian, all with a similar source. The term "Transplatense" is used to replace "Trans-Amazonian" events
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Microplastics in gut contents of coastal freshwater fish from Río de la Plata estuary.
Pazos, Rocío S; Maiztegui, Tomás; Colautti, Darío C; Paracampo, Ariel H; Gómez, Nora
2017-09-15
The presence of microplastics (MPs) in gut contents of coastal freshwater fish of the Rio de la Plata estuary was studied. Samples were taken in six sites where 87 fish belonging to 11 species and four feeding habits were captured. Presence of MPs was verified in the 100% of fish. The fibres represented the 96% of MPs found. The number of MPs in gut contents was significantly higher close to sewage discharge. There was not found relationship between number of MPs and fish length, weight or feeding habit. The spatial differences in mean number of MPs in fish observed in this study, suggest that environmental availability of MPs could be of great importance to explain the differences found among sampling sites analysed. This work represents the first study about the interaction between MPs and aquatic organisms in this important estuarine ecosystem of South America. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Ricardo Koroiva
Full Text Available We present a DNA barcoding study of Neotropical odonates from the Upper Plata basin, Brazil. A total of 38 species were collected in a transition region of "Cerrado" and Atlantic Forest, both regarded as biological hotspots, and 130 cytochrome c oxidase subunit I (COI barcodes were generated for the collected specimens. The distinct gap between intraspecific (0-2% and interspecific variation (15% and above in COI, and resulting separation of Barcode Index Numbers (BIN, allowed for successful identification of specimens in 94% of cases. The 6% fail rate was due to a shared BIN between two separate nominal species. DNA barcoding, based on COI, thus seems to be a reliable and efficient tool for identifying Neotropical odonate specimens down to the species level. These results underscore the utility of DNA barcoding to aid specimen identification in diverse biological hotspots, areas that require urgent action regarding taxonomic surveys and biodiversity conservation.
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Ricardo Miguel
2006-01-01
Full Text Available Este trabajo se fundamenta en la necesidad de obtener datos sobre la práctica del consentimiento informado realizado por odontólogos. Los datos pertenecen al Programa de Residencias Odontológicas Universitarias (ROU de la Facultad de Odontología de la Universidad Nacional de La Plata (UNLP. La investigación tiene como intención conocer diferentes aspectos respecto a las fortalezas y debilidades de su utilización actual. A partir de los datos, se puede concluir que, a pesar de que los conocimientos teóricos sobre la práctica del consentimiento informado son escasos, existe una tendencia significativa a destinar tiempo en la consulta dental para su empleo, especialmente en la nueva generación. Se considera imperativo incluir en la malla curricular y en los programas académicos odontológicos principios éticos y legales en relación con el proceso de consentimiento informadoEste trabalho fundamenta a necessidade de se obter dados sobre a prática do consentimento informado realizado por odontólogos. Os dados pertencem ao Programa de Residencias Odontológicas Universitárias (ROU da Faculdade de Odontologia da Universidade Nacional de la Plata (UNLP. A pesquisa tem como objetivo conhecer os diferentes aspectos, a respeito das forças e fraquezas de sua utilzação atual. A partir dos dados, se pode concluir que, apesar de serem escassos os conhecimentos teóricos sobre a prática do consentimento informado, existe uma tendencia significativa a destinar tempo na consulta dental para seu uso, especialmente na nova geração. Considera-se um imperativo incluir no curriculo de formação profissional e nos programas acadêmicos odontológicos, princípios éticos e legais relacionados com o processo do consentimento informadoThis work is based upon the need to obtain data on the practice of informed consent carried out by dentists. Data was generated from the University Residence Program at the Dentistry Faculty, L.P.N.U., Argentina. The
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El premio de la plata y la devaluación del vellón en Guipúzcoa en el siglo XVII
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Álvaro Aragón Ruano
2001-01-01
Full Text Available El presente artículo analiza la evolución del premio de la plata durante el siglo xvii en Guipúzcoa, donde aparecen dos modelos de comportamiento, siempre en relación con la abundancia y movimiento de la plata, que es el principal factor que explica las variaciones del premio. Se constata, no obstante, que en cada localidad los premios son diferentes, lo que demuestra la autonomía de las economías locales de Antiguo Régimen. Así mismo, hay que decir que las mayores repercusiones de este fenómeno se dejaron sentir en los mercados y en las transacciones locales, afectando principalmente a los consumidores. De todas formas, se demuestra la necesidad de seguir realizando investigaciones en los diferentes territorios que formaban la Corona, y desterrar definitivamente la generalización de datos como los de Hamilton.The next article analises the evolution of the silver's prize during the XVIIth Century in Guipúzcoa, where there arise two trends of behaviour, always related to the movement and abundance of the silver, which are the main factors that explain the changes of the prize. It is verified, nevertheless, that in each town the prizes are different, which shows the local economies' autonomy in the Ancient Regime. Besides, we should add that the main repercussion of this phenomenon was reflected in the local markets and transactions, mainly affecting the communities. In any case, it is stated the need to continué investigating in the different territories which formed the Crown, and to stamp out definetely the generalization of data, such as Hamilton's one.
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Mariana Gonzalez Insua
2015-03-01
Full Text Available A partir de Conferencia de Naciones Unidas sobre Medio Ambiente y Desarrollo (CNUMAD-92 se establecen las bases para un manejo integral de los Residuos Sólidos como parte del Desarrollo Sostenible; en este contexto Argentina desarrolla la Estrategia Nacional de Gestión de Residuos Sólidos Urbanos (ENGIRSU en el año 2005. Una de las estrategias para el estudio de los residuos como materiales posibles de ser valorizados, es el análisis de la cadena de valor. El presente trabajo tiene por objetivos contribuir al conocimiento de la Gestión Integral de los Residuos Sólidos Urbanos de la ciudad de Mar del Plata y analizar la revalorización de los mismos en el Circuito Formal (CF de recuperación bajo el enfoque de Cadena de Valor, visualizando a sus principales actores y su poder y control dentro de la cadena. Para alcanzarlos se realiza un revisión histórico-ambiental de la problemática de los residuos en Argentina hasta el desarrollo de ENGIRSU; puntualizando el análisis en la implementación de la estrategia en la ciudad de Mar del Plata focalizada en la etapa de separación de residuos, específicamente en la Planta de Separación y Clasificación operada por la Cooperativa CURA. Como resultado se evidencia una baja productividad de la planta como componente de GIRSU y un rol débil como eslabón dentro la cadena de valor de residuos sólidos urbanos.
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Portillo Alejo, Daniel
2015-01-01
Las nanopartículas de plata (AgNPs) han sido ampliamente usadas en las últimas décadas gracias a sus aplicaciones en áreas como la catálisis y la medicina. En catálisis, los principales focos de estudio se basan en la oxidación de compuestos como metanol y etanol, como propuesta para un posible método de obtención de hidrógeno molecular. En cuanto a las aplicaciones médicas, se ha probado que las AgNPs pueden reducir significativamente muchas infecciones bacterianas. Con este tipo de nanopa...
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Efecto de la plata sobre el proceso de síntesis por fusión de un pigmento del tipo azul ultramarino
Castillo, Wilmer; González, Luis; Sánchez, Selene; Ocanto, Freddy; Linares, Carlos F
2011-01-01
Se realizó la síntesis de pigmentos inorgánicos del tipo azul ultramarino a partir de la mezcla de zeolita A, carbonato de sodio, azufre elemental y contenido de plata entre un 0 al 5% p/p a una temperatura de 800°C por espacio de 4h. Los sólidos fueron caracterizados por la técnicas de difracción de rayos X (DRX), infrarrojo con transformada de Fourier (FTIR) y espectroscopia de reflectancia de UV a fin de verificar la estructura y coloración de los materiales obtenidos. Los resultados mostr...
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FAGES SANTANA, EDUARDO
2013-01-01
El presente y el futuro de la industria textil están íntimamente ligados al concepto de textil técnico, artículos éstos concebidos para su aplicación en diferentes segmentos de mercado: salud y ámbito hospitalario, industria naval, aeronáutica y de automoción, sector de construcción e ingeniería civil, defensa e industria militar, etc. En el presente proyecto de investigación se ha contemplado la funcionalización de fibras de polipropileno mediante la aditivación de nanopartículas de plata. D...
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Jaureguizar, Andrés Javier; Cortés, Federico; Milessi, Andrés Conrado; Cozzolino, Ezequiel; Allega, Lucrecia
2015-12-01
To improve the understanding of the environmental processes affecting small-scale gillnet fisheries along neighboring waters of estuaries, we analyzed the main climatic forcing and the environmental conditions, the fishery landing spatial and temporal variation, including the relative importance of site, distance to coast, temperature and salinity in the structuring of landed species profile. Data were collected monthly in two sites along the adjacent south coast of the Río de la Plata between October 2009 and September 2010. The gillnet fishery was dominated by four species (Cynoscion guatucupa, Micropogonias furnieri, Mustelus schmitti and Parona signata) from a total of 38 species landed, which accounted for 98.6% of total landings. The fishing effort and landings by the fishery were largely conditioned by the availability of fish species in the fishing grounds resulting from the combination of the species reproductive behavior and the predominant environmental conditions. The highest abundances for some species occurred before (M. furnieri, C. guatucupa, P. signata) or during the reproductive period (M. schmitti, Squatina guggenheim), while in other species it was associated with favorable environmental conditions during cold months (Squalus acanthias, Callorhinchus callorhynchus, Galeorhinus galeus) or warm months (Trichiurus lepturus). The predominant seasonal environmental conditions along the coast were mainly determined by the location of Río de la Plata boundary, whose spatial extent was forced by the wind patterns and freshwater discharge. The strong environmental dependence means that the small-scale fishery is in fact a seasonal trans-ecosystem fishery. This attribute, together that shared the resources with the industrial fishery and the overlap of the fishery ground with essential habitat of sharks, make this kind of small-scale gillnet fishery particularly relevant to be included in the development of a coastal ecosystem-based management approach.
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The vanguards and the passion for the real Anglo-Saxon Modernism in the Río de la Plata
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Carina González
2017-03-01
Full Text Available The well-known returning of the real marked the beginning of a new revision that emphasizes the crisis of representation and the question of realism as a genre opened to an uncommon leaking. This returning must be rethinking by the reflection about how the avant-garde promotes the debate on aesthetics and politics. This essay proposes an approach to this topic by analyzing modernism as the avant-garde that introduces a third position in the dialectics of high art and popular culture, art and life or the individual and the world. The study of the work of Joyce and Kafka will be addressing by the traditional readings and its approaches from reviews and translations written by main authors in the Río de la Plata´s region.
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Juliana Santa María
2009-01-01
Full Text Available This paper aims at looking into the job market situation in the Greater La Plata conglomerate, focusing its attention on the implementation of Temporary Work Programs as a clearly passive tool used by the State -especially during the last few decades- to deal with the population's employment issues. Based on the situation that the region presents, the specific situation of the municipality of Berisso which is part of the conglomerate will be looked into, in order to carry out an in-depth analysis of these types of policies' effective implementation forms and strategies on the municipal level. The Permanent Home Survey (EHP - INDEC, information provided by the Municipality and documents on Employment Policies and Programs will be used in order to complete this work.
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Incidence of early-onset dementia in Mar del Plata.
Sanchez Abraham, M; Scharovsky, D; Romano, L M; Ayala, M; Aleman, A; Sottano, E; Etchepareborda, I; Colla Machado, C; García, M I; Gonorazky, S E
2015-03-01
Early-onset dementia (EOD) is defined as dementia with onset before the age of 65 years. EOD is increasingly recognised as an important clinical and social problem with devastating consequences for patients and caregivers. Determine the annual crude incidence rate and the specific incidence rates by sex and age in patients with EOD, and the standardised rate using the last national census of the population of Argentina (NCPA), from 2010. Hospital Privado de Comunidad, Mar del Plata, Argentina, attends a closed population and is the sole healthcare provider for 17 614 people. Using the database pertaining to the Geriatric Care department, we identified all patients diagnosed with EOD between 1 January, 2005 and 31 December, 2011. EOD was defined as dementia diagnosed in patients younger than 65. The study period yielded 14 patients diagnosed with EOD out of a total of 287 patients evaluated for memory concerns. The crude annual incidence of EOD was 11 per 100 000/year (CI 95%: 6.25-19.1): 17 per 100 000 (CI 95%: 7.2-33.1) in men and 8 per 100 000 (CI 95%: 3.4-17.2) in women. We observed a statistically significant increase when comparing incidence rates between patients aged 21 to <55 years and ≥ 55 to <65 years (3 vs 22 per 100 000, P=.0014). The rate adjusted by NCPA census data was 5.8 cases of EOD habitants/year. This study, conducted in a closed population, yielded an EOD incidence rate of 11 per 100 000 inhabitants/year. To the best of our knowledge, this is the first prospective epidemiological study in Argentina and in Latin America. Copyright © 2013 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.
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Julia Hang
2014-12-01
Full Text Available El presente trabajo se propone analizar las diversas maneras en que se establecen relaciones sociales y políticas partir de una práctica deportiva. Se tomará el caso de un conjunto de nadadores “master” (adultos del Club Unidos de La Plata[1], quienes desde el año 2008 participan de la conducción política de la institución, para dar cuenta del modo en que se relacionan entre sí y con la política institucional del club, otorgando sentidos específicos a su participación “política”. Dado que la práctica de la natación es valorada por estos actores no sólo por su dimensión deportiva, sino principalmente por su dimensión sociable, aquí se buscará reflexionar sobre los modos en que a partir de la participación en una actividad deportiva y sociable, actores con diferentes historias y trayectorias políticas se vinculan entre sí, construyen relaciones políticas y disputan espacios de poder, tales como la presidencia del club o un lugar en la comisión directiva. A su vez, se buscará reflexionar sobre el vínculo que hubiera entre estas relaciones y otras esferas de la política local, considerando las apuestas subjetivas y los sentidos otorgados por los actores a la participación en este espacio. Palabras Clave: deporte, sociabilidad, política, club, natación. Abstract This paper analyzes the ways in which social and political relations are established from a sport. It will take the case of a group of "master" swimmers (adults of Club Unidos de La Plata , who since the 2008 year take part of the political leadership of the institution , to show the way they relate between each other and the institutional politics, giving specific senses to their participation in "politics" . Since the practice of swimming is valued by these actors not only for its sportive dimension , but mainly for its social dimension , here we seek to reflect on the ways from participating in a sportive and sociable practice , actors with
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Mesoproterozoic evolution of the Rio de la Plata Craton in Uruguay: at the heart of Rodinia?
DEFF Research Database (Denmark)
Gaucher, Claudio; Frei, Robert; Chemale, Farid
2011-01-01
Mesoproterozoic volcanosedimentary units and tectonic events occurring in the Ri´o de la Plata Craton (RPC) are reviewed. A belt consisting of volcanosedimentary successions exhibiting greenschist-facies metamorphism is exposed in the eastern RPC (Nico Pe´rez Terrane) in Uruguay. The Parque UTE...... and top, and Conophyton-bearing limestones and massive dolostones in the middle. A U–Pb LA-ICP MS zircon age of 1,433 ± 6 Ma is reported here for lapilli-tuffs at the base of the Mina Verdu´n Group (Cerro de las Vi´boras Formation). This age shows that the Mina Verdu´n Group immediately postdates...... the Sarandi´ del Yi´ megashear. We report a U–Pb LA-ICP MS zircon age (upper intercept) of 3,096 ± 45 Ma for metatonalites of the La China Complex (Nico Pe´rez Terrane), which yield a lower intercept age of 1,252 Ma. A proto-Andean, Mesoproterozoic belt is envisaged to account for abundant Mesoproterozoic...
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Análisis de las causas de muerte de los primeros habitantes de la ciudad de La Plata (1887
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Flores, Olga B.
2003-01-01
Full Text Available El presente trabajo constituye un estudio preliminar que forma parte de un proyecto más amplio acreditado por la Universidad Nacional de La Plata y avalado por la Municipalidad de esa localidad "El Cementerio de La Plata. Su contexto histórico". Nuestra investigación se basó fundamentalmente en el análisis de las actas de defunción del Archivo del Cementerio Municipal con el fin de indagar sobre la incidencia diferencial o no de las causas de muerte en relación con la nacionalidad, el sexo, la edad, la profesión, entre otras. Estos datos fueron volcados en planillas con las que se sistematizó la información para toda la población. A partir de esta población, se determinó una muestra compuesta por todos los individuos de ambos sexos que se encuentran en las sepulturas en tierra y abarca el primer año de funcionamiento del Cementerio Municipal. El objetivo del presente trabajo fue caracterizar cómo se distribuyeron las causas de muerte y su incidencia sobre los grupos de edad, género y grupo social, en los decesos ocurridos durante 1887. Según se desprende de los datos analizados, la probabilidad de fallecer antes de cumplir el año de vida es de más del 60%. Las razones para esta alta mortalidad infantil deberán buscarse en las condiciones sanitarias y nutricionales imperantes en la época y para este grupo social, considerando las enfermedades de mayor incidencia en los subadultos; también deben agregarse algunos casos de fallecimiento en los primeros días de vida por falta de desarrollo. En este grupo de edad las causas de muerte más comunes corresponden a las que pertenecen al sistema digestivo, respiratorio, infecciosas y en adultos a enfermedades cardiovasculares, cerebrales, etc.
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The Asamblea del Año XIII in the Rio de la Plata: Eternal Laurels to End the Revolution
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Esteban Buch
2016-09-01
Full Text Available The Asamblea del año XIII, the 1813 Constitutional Assembly in the Río de la Plata, represents at its best revolutionary velocity, with its allegro rhythm towards wider liberties and a more perfect equality, towards an independence of the nation that, without being officially declared, inspires many of its gestures, like the creation of Argentina’s national anthem. A contemporary observer fond of anachronisms might find in it a confirmation that movement is an essential element of democracy. Yet, this dynamic perception should be balanced by reminding that the Assembly’s main project is not to accelerate the revolution, but to terminate it. “Close the period of the revolution, open the epoch of peace and freedom”, says its inaugural declaration. This paper focuses on the tension between these two conceptions of historical temporality.
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Mallo, Paulino E.; Artola, María Antonia; Zanfrillo, Alicia Inés; Morettini, Mariano; Galante, Marcelo Javier; Busetto, Adrián Raúl; Pascual, Mariano Enrique
2006-01-01
El propósito del presente trabajo es caracterizar el comportamiento de los indicadores contables de distintas empresas de pequeña y mediana envergadura del medio socioproductivo de la ciudad de Mar del Plata que puedan incidir en la determinación de la morosidad en el pago de tributos, sean nacionales, provinciales o municipales, a través de la aplicación de lógica difusa. Para ello se trabajó con una muestra de empresas representativas de distintos sectores productivos y comerciales de la ci...
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Proyecto integral de acondicionamiento de cuerpos momificados de la colección del Museo de La Plata
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Reca, María Marta
2009-01-01
Full Text Available Con motivo de la decisión institucional de no exhibir restos humanos de procedencia americana, desde la Unidad de Conservación y Exhibición del Museo de La Plata se inició la delicada tarea de retirar las piezas de la sala de exhibición y acondicionar un espacio especial para el resguardo de la colección de cuerpos momificados. Dicha colección está conformada por veinte cuerpos en diferente estado de conservación y con características específicas. El presente estudio tiene por objeto dar cuenta de los procedimientos y las distintas etapas a considerar en un trabajo planificado y sistemático. En tal sentido, se explicitan, desde la conservación preventiva, los criterios que orientaron cada una de las etapas. El proyecto, en curso, contempla las instancias de evaluación, registro, tratamiento, definición de los contenedores y características del depósito.
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Bueno, C; Brugnoli, E; Figueira, R C L; Muniz, P; Ferreira, P A L; García Rodríguez, F
2016-12-15
Montevideo Bay is located in the middle zone of the Rio de la Plata, and since the foundation of the city, several key economic and environmental policies affected the industry, and thus, metal inputs into this ecosystem. The aim of this study is to evaluate the sedimentary geochemical record of Montevideo Bay, in order to determine the historical inputs of anthropogenic metals to the system. In addition, environmental and economic policies of the country were taken into account to infer the relationship between them and the historic metal input. Concentrations of aluminum, chromium, copper, lead, scandium and zinc were analyzed and the EF and SPI indices were calculated. The analysis showed that since Montevideo foundation, metal concentrations increased in accordance with industry development, and the indices as well as the metal concentration represent a reliable footprint of the history of different economic and environmental policies influencing historical industrial activities. Copyright © 2016 Elsevier Ltd. All rights reserved.
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Study of sediment behaviour in Rio de la Plata, Punta Carmelo area with use of radioactive trace
International Nuclear Information System (INIS)
Vianna Bandeira, J.; Godinho Pinto, G.; Suarez Antola, R.
1998-01-01
This work is related to the sedimentological studies with the application of radioactive tracers, carried out in the region of Puerto Carmelo, Rio de la Plata-Uruguay, under the Tc Project of the International Atomic Energy Agency (IAEA) URU/8/009, with the objective of evaluating the bed load transport of sand, in the region where a new access channel to the harbour of Carmelo, was designed. These studies, performed together hydraulic measurements, were important for the comprehension of the behaviour of the sediment transportation under the action of the hydrodynamic agents (currents and waves); the determination of the bed load rate and its application to the evaluation of the maintenance dredging, the definition of the optimum path for the access channel, based on the deposition process of the injected tracer, 30 cm above the bottom. The maximum accretion rate is for the designed channel is around 11000 m3/year. (author)
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Julieta Susana Garcias Franco
2014-07-01
Full Text Available This paper presents partial results of an ongoing study whose objective is to map the approaches and theoretical trends in the educational policy theoretical field. More specifically, this study characterizes and describes the theoretical trends of the subject Educational Policy contents in the 50s of the last century in the Buenos Aires and La Plata Federal Universities. 46 programs were analyzed in the period 1917-1959, as well as the bibliography and theoretical background linked to the professors who were responsible for the subject. Surveying professors’ biographies, it was observed that in the period prior to the institutionalization of this field, the debate focused on the positivism or anti-positivism theoretical trends. Later on, the theoretical trends that permeated the programs from 1953 to 1954 had more distinct shades of positivism and anti-positivism than those of the beginning of the century, and three axes were observed: the national tradition, the pedagogical progressivism and the Spanish Krausism.
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Agustín Nava
2017-07-01
Full Text Available This paper is inscribed within studies on the history of the labor movement during the years '60 and '70 in Argentina and aims to analyze the cycle of general strikes and labor conflictivity that took place more specifically between the years 1969-1972 on a particular region: the Gran La Plata. Through a qualitative and quantitative analysis we will approach the dynamics of general strikes and their impact on our study region, as a kind of struggle that allows us to analyze the different tendencies and forms assumed by the conflict, the degrees of unity within the labor movement, the dynamics of trade unions, alliances with other social forces and the relationship with the state. Therefore, this article contributes to study not only certain specific dynamics of labor conflictivity in our study region, but also the more general cycle of social protest and political radicalization that took place in Argentina during the sixties and seventies
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Leis, Alejandro Nahuel
2015-01-01
El manejo de los residuos sólidos urbanos en Argentina conlleva principalmente dos problemáticas económicas: su elevado peso relativo en los presupuestos municipales y sus impactos ambientales, que constituyen externalidades negativas. Este trabajo analiza el sistema actual de recolección de residuos sólidos domiciliarios de la ciudad de Mar del Plata en vista de la disposición municipal que promueve la separación en origen entre orgánicos y reciclables que, a su vez, constituye uno de los ej...
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Romanazzi, Pablo Gustavo
2011-01-01
Las inundaciones que se producen en la cuenca media del arroyo del Gato afectan a gran parte del casco fundacional de la ciudad de La Plata y barrios aledaños. El sistema de desagües pluviales presenta en la actualidad graves deficiencias para conducir los excedentes superficiales generados aún por tormentas de baja severidad. Este es un caso de estudio típico de la problemática de la inundación urbana, donde el crecimiento periférico de la ciudad no fue anticipado por una planificación adecu...
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Théodoridou, Zoe D; Koutsoklenis, Athanasios; del Cerro, Manuel; Triarhou, Lazaros C
2013-01-01
The interdisciplinary trend in "Mind, Brain, and Education" has witnessed dynamic international growth in recent years. Yet, it remains little known that the National University of La Plata in Argentina probably holds the historical precedent as the world's first institution of higher education that formally included neurobiology in the curriculum of an educational department, having done so as early as 1922. The responsibility of teaching neurobiology to educators was assigned to Professor Christofredo Jakob (1866-1956). In the present article, we highlight Jakob's emphasis on interdisciplinarity and, in particular, on the neuroscientific foundations of education, including special education.
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Mallo, Paulino E.; Artola, María Antonia; Zanfrillo, Alicia Inés; Morettini, Mariano; Galante, Marcelo Javier; Busetto, Adrián Raúl; Pascual, Mariano Enrique
2007-01-01
Continuando con el objetivo buscado en el trabajo presentado en el Coloquio de Estadística del año 2006, en esta oportunidad aportamos una nueva ponencia que amplía las metodologías utilizadas en aquella oportunidad, a la vez que profundiza las conclusiones a las que se había arribado entonces. El propósito es caracterizar el comportamiento de los indicadores contables de distintas empresas de pequeña y mediana envergadura del medio socio-productivo de la ciudad de Mar del Plata que puedan in...
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Passarella, Luciano
2012-01-01
La Universidad Nacional de La Plata, cuenta desde su fundación con un escudo que la representa. A más de cien años de su generación sigue siendo hoy el símbolo más importante de su identidad, formando parte de la marca vigente actualmente. Dicho escudo posee una construcción singular y se enmarca en lo que dentro del universo de signos de universidades constituyen los escudos alegóricos utilizados como marcas. En el presente trabajo se parte de la idea de que en cada época o período histór...
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Giuseppe Gatti
2012-12-01
Full Text Available The present study analyzes the role of the process of memory recovery in the Uruguayan contemporary literary space. The article focuses on the dynamics of recovery of the past in the work of the Montevidean Hugo Burel (born in 1951, especially in his novel Tijeras de Plata (2003. The first part of our study analyses how the novel describes – in a symbolic form – the geo-social changes that have characterised the Uruguayan space from the second half of the 20th century (decentralization of urban population; gradual decline in the social, cultural and economic structure of many central neighbourhoods. We examine the narrative forms used by Burel (short stories within a frame in the light of these phenomena, and consider in turn another type of fragmentation, of an extra-literary nature: investigating nature of the relationship between literature and the idiosyncrasy of Uruguayan social world: we refer to a frequent sensation of “fracture with the past” that envelops Uruguayan society. In the second part of the article we demonstrate why Tijeras de Plata can be considered as a “literary tool” to recover a missing past: the novel develops as a “story of past memories”, focusing on the process of impoverishment that affects many urban zones of Montevideo. On the other hand, the double operation of rescue (first the restoration of the individual memories related to the neighbourhood, then the revival of the prosperity once banished from the city suggests an evocation of a past of happiness and can be considered as literary means of rescuing that old world form oblivion. In conclusion, it is possible to read the novel as a metaphorical reflection on the decline of a “lost country”.
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Oyhenart, Evelia Edith
2013-12-01
Full Text Available En el presente trabajo se caracterizaron el estado nutricional, las enteroparasitosis y las condiciones socio-ambientales de niños residentes en el Casco urbano y 11 localidades del Partido de La Plata, provincia de Buenos Aires, mediante un estudio transversal. Se midieron peso y talla de 6.397 niños entre 4.0 y 13.9 años. Se calculó el índice de masa corporal y se estimó el estado nutricional utilizando NHANES III. Las variables socio-ambientales se relevaron mediante encuesta estructurada. El análisis parasitológico se realizó en 729 niños sobre muestras seriadas de materia fecal analizadas mediante la técnica de Ritchie y escobillado anal. Los resultados globales indicaron: 22.1% de exceso de peso, 8.7% de desnutrición y 68.5% de parasitosis, siendo más prevalentes Enterobius vermicularis (38.7%, Blastocystis hominis (36.1%, Giardia lamblia (19.1% y protozoos comensales (26.1%. Los geohelmintos tuvieron valores inferiores (9.3%. El partido de La Plata presenta gran heterogeneidad en el estado nutricional y las infecciones parasitarias de los niños por cuanto resultan dependientes de las características socio-ambientales. Las deficientes condiciones ambientales, el bajo nivel educativo y la falta de trabajo formal de los padres explicarían la coexistencia de parasitosis y desnutrición infantil, prevaleciendo la de tipo crónico. Por otra parte, las localidades en las que hay menor grado de cobertura de servicios urbanos básicos, pero los padres poseen mayor nivel educativo y trabajo formalizado, presentan prevalencias más elevadas de exceso de peso.
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Rollán, María Cristina; Protto, Victoria; Medina, Rocío; López, Silvina Marianela Yanil; Vera Bahima, José; Ronco, Blanca Lía; Saparrat, Mario Carlos Nazareno; Balatti, Pedro Alberto
2013-01-01
Surveys aimed at evaluating the incidence and severity of a new disease that developed in greenhouses cultivated with tomato (Solanum lycopersicum L.) were performed during 2009 and 2010 in greenhouses of the cultivars Elpida (Enza Zaden) and Colibrí (Clause) in an area of tomato production known as the Cinturón Hortícola de La Plata (the “horticultural belt of La Plata”). The disease had a 100% prevalence and 90% incidence within the ten 250 m greenhouses that were monitored in 2009, 2010, a...
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Diana Sierra
2006-10-01
Full Text Available Introducción. La leishmaniaisis es una enfermedad encontrada en focos naturales de infección donde están presentes insectos vectores y mamíferos reservorios deLeishmania. Objetivo. Registrar por primera vez la presencia de Leishmania (Leishmania mexicana Biagi, 1953, en el corregimiento de San Matías, municipio de Gómez Plata, departamento de Antioquia. Materiales y métodos. La especie fue aislada de un paciente con leishmaniasis cutánea localizada e identificada por la técnica de Inmunofluorescencia utilizando anticuerpos monoclonales específicos de especie y electroforesis de enzimas . Resultados y conclusión. Su perfil isoenzimático similar al de las cepas de referencia L. (L. mexicana (MNCY/BZ/62/M379 y L. (L. mexicana (MHOM/BE/82/BEL21, permitió concluír que la especie aislada del paciente es L. (L. mexicana.
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Pilorgé Étienne
2012-11-01
Full Text Available The 18th International Sunflower Conference took place in Mar del Plata, Argentina, in February, 2012. The key-points and evolutions of sunflower research were presented, in the fields of agronomy, physiology, genetics and genomics, crop protection, quality and markets. Major evolutions can be observed concerning the sequencing of sunflower genome, announced to be complete by the end of 2012, but also concerning the use of models and the progress in the studies on the interactions between varieties genetic pattern, environment and crop management practices. In crop protection aspects, the evolutions of the major pathogens, downy mildew and Orobanche cumana, have been discussed, as well as the breeding efforts for genetic resistances, or the advances concerning the herbicides tolerant varieties. Evolutions in oil quality aspects have been exposed too, such as varieties enriched in stearic acid, or tocopherols, or with low contents in saturated fatty acids.
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Giannuzzi, L.; Carvajal, G.; Corradini, M. G.; Araujo Andrade, C.; Echenique, R.; Andrinolo, D.
2012-01-01
Water samples were collected during 3 years (2004–2007) at three sampling sites in the Rio de la Plata estuary. Thirteen biological, physical, and chemical parameters were determined on the water samples. The presence of microcystin-LR in the reservoir samples, and also in domestic water samples, was confirmed and quantified. Microcystin-LR concentration ranged between 0.02 and 8.6 μg.L−1. Principal components analysis was used to identify the factors promoting cyanobacteria growth. The proliferation of cyanobacteria was accompanied by the presence of high total and fecal coliforms bacteria (>1500 MNP/100 mL), temperature ≥25°C, and total phosphorus content ≥1.24 mg·L−1. The observed fluctuating patterns of Microcystis aeruginosa, total coliforms, and Microcystin-LR were also described by probabilistic models based on the log-normal and extreme value distributions. The sampling sites were compared in terms of the distribution parameters and the probability of observing high concentrations for Microcystis aeruginosa, total coliforms, and microcystin-LR concentration. PMID:22523486
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Ferraro, Rosana; Zulaica, Laura
2012-01-01
El periurbano de Mar del Plata exhibe una alta heterogeneidad de usos de la tierra característicos de las zonas de transición. El ordenamiento de estos espacios demanda la identificación de potencialidades y limitaciones ambientales que favorecen o condicionan el desarrollo de actividades urbanas y rurales. Tomando como referencia los antecedentes existentes en el área, el presente trabajo tiene como objetivo evaluar la aptitud de las tierras del periurbano marplatense para distintos tipos de...
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Crecimiento y nutrición en preescolares de la ciudad de La Plata
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Ranieri, José
2001-01-01
Full Text Available El objeto del presente trabajo es determinar el estado nutricional en una población proveniente del área urbanomarginal de La Plata compuesta por 215 niños de ambos sexos, de edad preescolar (2-5 años. Se relevaron las variables peso/edad; talla/edad y perímetro cefálico/edad incorporando además la variable knemométrica (tomada con pie de rey desde el punto superior de la rótula hasta el punto más bajo del talón. Los datos se procesaron mediante pruebas de Kolmogorov-Smirnov y Levene, análisis de varianza (ANOVA, correlación y regresión. Se calcularon diferencias porcentuales relativas entre medias (PDM. La muestra presentó distribución normal. Los puntajes Z indicaron valores entre -0.3 y 1.6. El ANOVA mostró para el factor edad diferencias significativas en todas las variables analizadas y para el factor sexo sólo en perímetro cefálico. Las correlaciones entre la variable knemométrica con las restantes variables fueron altamente significativas. Los resultados obtenidos permiten determinar que la población analizada presenta un estado nutricional óptimo respecto de los estándares del NCHS. La evaluación knemométrica constituye un buen indicador del crecimiento, dada su correspondencia con aquellos usualmente empleados.
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Daniela S Nitiu
2011-12-01
Full Text Available Se presentan los primeros datos sobre variaciones estacionales de polen y esporas fúngicas en su conjunto en la atmósfera de la ciudad de La Plata durante julio 2000 / junio 2001. El total de bioaerosoles fue de 201889.15 de los cuales el 15% correspondió a 54 tipos polínicos y el 85% a 79 tipos esporales. El Índice Polínico estuvo dado en un 74% por Polen Arbóreo (PA y en un 26% por Polen Herbáceo (PNA. La máxima concentración de PA tuvo lugar en septiembre con granos provenientes de Platanus y Fraxinus. El PNA presentó dos picos, el primero en diciembre procedente de Poaceae y el segundo en marzo debido a Ambrosia. Con respecto al componente fúngico, se identificaron esporas de Oomycota, Zygomycota, Myxomycota, Ascomycota y Basidiomycota. Estos bioaerosoles estuvieron presentes durante todo el año y en altas concentraciones siendo más abundantes en verano - otoño Las mitosporas de Hongos Imperfectos dominan la nube superando el 44% del total del Índice Esporal. El máximo aporte se registró en febrero dado por las esporas de Cladosporium. Se identificaron dos períodos estacionales en los cuales se hallan simultáneamente altas concentraciones de polen y esporas fúngicas. El primero se desarrolla en primavera y está integrado por Platanus, Fraxinus y Aspergillus / Penicillium y el segundo es estival e involucra a Ambrosia, Alternaria y Cladosporium.We present the first data on representativeness and seasonal variation of pollen and fungal spores as a whole in the atmosphere of the city of La Plata during july 2000 / june 2001. Total was 201889.15 bioaerosols, 15% of which was contributed by 54 pollen types and 85% by 79 spore types. The Pollinic Index came from arboreal pollen (PA in 74% and herbaceous pollen (PNA in 26%. The PA maximum concentration took place in september due to Platanus and Fraxinus. The PNA presented two peaks, one in december due to Poaceae, and the other one in march from Ambrosia. In regard to the
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Jumar, Fernando Alberto; Molinié, A.; Merle, A.
2004-01-01
La guerra, como lo subraya Fernand Braudel, siempre pone en movimiento las flrees enproflndeur que son las economías, los Estados, las civilizaciones. Como este mismo autor constata, después de la batalla de Lepanto el escenario de la guerra pasa del Mediterráneo «au Nord, a l'Ouest sur I'Atlantique - et pour des siecles -la où elle doit etre, la oú bat le coeur du monde». Y en el extremo sur del Atlántico ocupado por los europeos en los tiempos modernos, está el Río de la Plata, y la guerra ...
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Orden y ambigüedad en la formación territorial de Río de la Plata a fines del siglo XVIII
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Guillermo Wilde
2003-07-01
Full Text Available Por mucho tiempo la heterogénea población que habitaba la región Río de la Plata, en las fronteras entre España y Portugal, hacia fines del siglo XVIII fue asociada con la barbarie. Con el fin de homogeneizar a esta población y ajustar su comportamiento a las leyes indianas, la monarquía española implementó varias políticas de control. Sin embargo, en el corto plazo estas políticas no lograron modificar las prácticas económicas, políticas y simbólicas de esta población ni su débil percepción del Estado. Por el contrario, los actores locales mantuvieron sus dinámicas relativamente autónomas hasta casi la mitad del siglo XIX. Este artículo analiza la contradicción entre las representaciones del Estado sobre esos actores locales, construidos como "alteridad", y las dinámicas concretas que los caracterizaban, sus percepciones del territorio y el Estado, y sus estrategias para evadir los controles de las autoridades oficiales.For a long time, the heterogenous population that inhabited the Río de la Plata Region, in the borderlands of Spain and Portugal, toward the end of 18th Century, was associated to barbarism. To make that population homogenous and to adjust its behavior to indigenous Law, the Spanish Monarchy carried out several policies of control. However, in a short term these policies were neither able to modify the economic, political and symbolic practices of that population, nor were they able to weaken the perception this population had of the State. On the contrary, local actors kept their own dynamics until almost the first half of the 19th Century. This paper analyses the contradiction between State representations of local actors and the concrete dynamics that characterized them, their perceptions of territory and State, and their strategies for avoiding control by official authorities.
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Determination of risk indices in quarries of two basins in La Plata Municipality Argentina
International Nuclear Information System (INIS)
Cabral, M.; Crincoli, A.; Gimenez, J.; Hurtado, M.
2004-01-01
Soil extraction is one of the main causes of degradation of this resource in Buenos Aires province. In La Plata municipality, soil is extracted at different depths for a variety of uses. Deep soil extraction creates quarries which have a negative impact on the environment, the landscape, the real estate value and life quality. The inundated quarries become precarious swimming places where many people have drowned. When the quarries are used as garbage dumps, they can concentrate disease vectors or pollute groundwater through their leachates. The face-cuts are often near vertical and can be susceptible to collapse. The methodology to calculate the risk index is based on the hypothesis that risk variables can be identified, individually assessed and combined in such a way that they would provide a numerical value reflecting the likelihood of accidents or diseases occurring as a consequence of quarry's presence. The general objective of the project is to obtain an index for the quarries of the studied basins aimed at warning local authorities and affected persons about the sites where protection and reclamation measures are more urgently needed. The values obtained are represented on a map showing the risk class of each quarry. It is concluded that the methodology is useful to determine priorities and can prove a good management tool for those involved in this problem [es
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María Graciela León Matamoros
2010-11-01
Full Text Available The wars of independence in Latin America and the consequent process of building the nation accounted for the Spaniards unsteadiness, reflected, in various degrees of intensity, in emerging countries. The intent of this paper is to present the measures that the governments of two different territories such as Mexico and Río de la Plata, adopted against the Spaniards for legitimacy. The position of both governments reveal the relationships and affronts which every country kept to their former conquerors, and the levels of dependence on the Iberian that made inoperable, in many cases, the intention of decrease their privileges. Therefore the aim is to show the history, the parallels and differences that these countries had in their provisions against the Spaniards.
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Energy Technology Data Exchange (ETDEWEB)
Camilion, M.C.; Hurtado, M.A. [CISAUA-UNLP: Centro de Investigaciones de Suelos y Aguas de Uso Agropecuario, Facultad de Ciencias Naturales y Museo, Univ. Nacional de La Plata, La Plata (Argentina); Manassero, M.J. [CIG-UNLP-CONICET: Centro de Investigaciones Geologicas, Facultad de Ciencias Naturales y Museo, Univ. Nacional de La Plata, La Plata (Argentina); Ronco, A.E. [CIMA-UNLP-CONICET: Centro de Investigaciones del Medio Ambiente, Facultad de Ciencias Exactas, Univ. Nacional de La Plata, La Plata (Argentina)
2003-07-01
The compositional study of suspended matter in water from rivers of different latitudes and climates has revealed that the fine fraction reflects both substrate lithology from source areas or topsoil composition along the course. Metal distribution patterns are also strongly related to the clay mineral fate in fluvial aquatic systems. For the particular case of the coastal area of the Rio de la Plata estuary in South America, previous studies have, on the one hand, focused on the analysis of distribution patterns of heavy metals in bottom river sediments and, on the other hand, on the assessment of metal contents in topsoils. The present study was conducted to evaluate the Cu, Pb and Zn distribution in soils and sediments from four drainage basins crossing two differentiated geomorphologic units composed of unconsolidated materials and to understand the metal behaviour. (orig.)
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Daniel E. Martínez
2013-01-01
Full Text Available Sedimentos de tipo loéssico cubren una superficie aproximada de 1.800.000 km2 en la llanura Pampeana de Argentina, formando un sistema acuífero que es utilizado para abastecimiento de agua a ciudades y la población rural en la región. Este sistema acuífero suministra el agua que sustenta las actividades productivas que contribuyen en un 60% al producto bruto nacional. Es este trabajo se realiza un estudio detallado en un sector del acuífero próximo a la ciudad de Mar del Plata, provincia de Buenos Aires, en el que se localizan tres rellenos sanitarios. El principal objetivo es caracterizar los procesos geoquímicos que dan origen a la composición observada del agua subterránea. Se perforaron cinco pozos para la toma de muestras de agua y sedimentos, y evaluar el impacto de la infiltración del lixiviado sobre esos procesos. Se determinó la composición textural y mineralógica de los sedimentos y la composición química del agua. Las relaciones de equilibrio entre la fase sólida y la solución se determinó utilizando programas específicos. Se concluye que la composición química observada en la aguas es consecuencia principalmente de procesos de equilibrio con calcita e intercambio catiónico con adsorción de calcio y liberación de sodio. La disolución de minerales de sílice amorfo, y la hidrólisis de silicatos en forma subordinada, da origen a altas concentraciones de sílice en las aguas. La mezcla con la infiltración del lixiviado incrementa las concentraciones de los iones conservativos cloruro y nitrato, pero no se modifican en general los procesos hidrogeoquímicos mayoritarios.
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Medición de placas astrométricas obtenidas con el telescopio Astrográfico de La Plata
di Sisto, R. P.; Orellana, R.
El Observatorio de La Plata cuenta con un gran número de placas de asteroides y cometas obtenidas con el telescopio astrográfico, que cubren gran parte del cielo del hemisferio sur. En 1996 se recopilaron y clasificaron 2187 placas (Beca para estudiantes de la AAA 1996) de las cuales 2031 corresponden a asteroides. Los datos de cada placa se volcaron en una base de datos creada para facilitar su manejo y preservar la información. A partir de este trabajo se revisaron los MPC electrónicos y se identificaron aquellas placas de asteroides pertenecientes a nuestra base de datos cuyos resultados no fueron publicados en los mismos. De un total de 400 placas que no aparecían publicadas sobresalía un paquete constituído por 40 placas obtenidas en 1977. Estas últimas fueron reducidas utilizando las posiciones y movimientos propios de las estrellas de referencia obtenidas del catálogo SAO 2000 dadas para el sistema FK5. Las posiciones calculadas fueron enviadas y publicadas en los Minor Planet Circulars (MPC).
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Fernanda Rebelo-Pinto
2016-12-01
Full Text Available This paper analyzes how immigration process in the Rio de Plata Basin countries, specifically Brazil and Argentina, promoted inflexions in the sanitations agreements in the end of 19th century. The port is a device within in which are defined knowledge and standards and are established interventions on people in transit, particularly immigrants. The barriers in the agreements between these countries were not only related to controversies within medical and scientific communities but also to political and economics tensions linked to the labor immigrants disputes. In the beginning of 20th century, we can see a shift of interest and issues related to public health: epidemic control was not enough. The states must guarantee some benefits to the populations, especially heath care. This new view is analyzed according to the understanding and uses of the liberal ideology concerning risk self-regulations, collectivization of welfare and expanding of civil and social rights. This process is leveraged in parts by the inclusion of the immigrants in theses societies.
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J.F. Salvador Sanz
2011-09-01
Full Text Available La plata es un producto utilizado como agente antimicrobiano desde la antigüedad y ya a finales del siglo XIX se empezaron a utilizar compuestos de plata con finalidades médicas. La utilización tópica de la crema de sulfadiazina argéntica al 1 % se considera mayoritariamente como tratamiento de elección para las quemaduras a fin de tratar o prevenir la infección local. El objetivo de este artículo es comparar el tratamiento con Acticoat® (plata nanocristalina 15 nanómetros frente al tratamiento con sulfadiazina argéntica, ambos regímenes en igualdad de condiciones y un mismo centro de quemados. También se realiza una revisión de la literatura reciente sobre los factores de riesgo para la infección en quemaduras, las medidas que se utilizan para prevenirla y su importancia en la disminución de la morbi-mortalidad.Silver is a product that has been used as antimicrobial agent from ancient times; at the end of the XIXth century silver compounds were used with medical purposes. The use of silver sulfadiazine to 1 % cream is considered as gold standard for local treatment of burns in order to prevent or to treat local infection We compare treatment with Acticoat® (nanocrystalline silver 15 nanometers and silver sulfadiazine, both sistems on equal terms and in the same medical burned center. We review recent literature of risk factors for burn infection, methods to prevent it and to dininish morbimortality in burned patients.
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GABRIEL GENZANO
2006-06-01
Full Text Available Blackfordia virginica is a well-known invasive medusa inhabiting estuarine areas. It was recently detected in northern Argentina, constituting the first record of invasive hydromedusa for the Argentine Sea. In this work more than 1,500 plankton samples in the southwestern Atlantic Ocean (34-55º S from 1983 to 2000 were analyzed. More than 5,000 specimens per sample of B. virginica were found in Río de la Plata estuary for the first time in February 2000. This river is one of the large waterways of South America with an intense nautical traffic and several exotic species has been recorded here, mainly due to trans-oceanic shipping traffic. It is important to point out that we found medusae of both sexes (therefore this species could be introduced in either the medusa or the polyp stages or both, different size classes (including very small juveniles and maturation stages, and in such high numbers that would suggest local reproduction. For this reason the recent finding of this hydromedusa could represent the starting point of an successful introductionBlackfordia virginica es una medusa invasora reconocida por habitar áreas estuariales. Recientemente fue descubierta en el norte de Argentina, constituyendo el primer registro de una hidromedusa invasora para el mar argentino. En este trabajo se analizaron más de 1.500 muestras de plancton en el Océano Atlántico sudoccidental (34-55º S desde 1983 hasta el año 2000. Más de 5.000 especímenes por muestra fueron encontrados por primera vez en el estuario del Río de la Plata durante febrero del año 2000. Este río es una de las mayores vías de agua de América del Sur, posee un intenso tráfico náutico y varias especies exóticas se han registrado allí, principalmente debido al tráfico marítimo transoceánico. Es importante señalar que se encontraron medusas de ambos sexos (por lo tanto esta especie podría haber sido introducida en su estadio medusa, pólipo o ambos, con diferentes
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International Nuclear Information System (INIS)
Bueno, C.; Brugnoli, E.; Figueira, R.C.L.; Muniz, P.; Ferreira, P.A.L.
2016-01-01
Montevideo Bay is located in the middle zone of the Rio de la Plata, and since the foundation of the city, several key economic and environmental policies affected the industry, and thus, metal inputs into this ecosystem. The aim of this study is to evaluate the sedimentary geochemical record of Montevideo Bay, in order to determine the historical inputs of anthropogenic metals to the system. In addition, environmental and economic policies of the country were taken into account to infer the relationship between them and the historic metal input. Concentrations of aluminum, chromium, copper, lead, scandium and zinc were analyzed and the EF and SPI indices were calculated. The analysis showed that since Montevideo foundation, metal concentrations increased in accordance with industry development, and the indices as well as the metal concentration represent a reliable footprint of the history of different economic and environmental policies influencing historical industrial activities. - Highlights: • Trace metal record of a sediment core of Montevideo Bay/harbor was studied. • The historic inputs of metals in the area were inferred. • System degradation evolved from anthropogenic impacts. • A relationship between pollution and environmental/economic policies was discussed.
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International Nuclear Information System (INIS)
Ocon, C.S.; Capitulo, A. Rodrigues; Paggi, A.C.
2008-01-01
The objective of this work was to analyse zoobenthic assemblages in the coastal sector of the Rio de La Plata, Argentina, after a petroleum spill. Sampling stations were located in representative sites of various landscapes. Structure, composition, physico-chemical parameters and seasonal changes were recorded in order to assess taxocenosis evolution during the period 1999-2003. Recovery signs were estimated by means of biotic indices and the presence of sensitive species. Tolerant species were dominant in heavily polluted sites, with low diversity and water quality values, according to the biotic indices used. In certain zones, sediment quality remains impoverished, with a visible oil film on the surface. However, during the last sampling, some points showed an increase in biotic indices, pointing to a slight improvement in environmental conditions. - Oil spill impact was evaluated by zoobenthos response in an estuarine system
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Integrating Geological map of the Plata Basin and adjacent areas: release Bulletin
International Nuclear Information System (INIS)
Preciozzi, F.; Spoturno Pioppo, J.; Medina, E.
2001-01-01
During the 1st Meeting of the Geological Surveys of the Southern Cone Countries, held in the city of Porto Alegre (Rio Grande do Sul - Brazil) in November 1995, it was born the idea of a set of activities that it had aimed at developing integration , technical cooperation and scientific exchange between these institutions, resulting in a concrete proposal in order to develop a map of geological, metallogenic and hydrogeological basins of the Parana and Plata integration; which provide the basic information needed for the further development of mineral resources maps approach to groundwater, gold, ornamental stones, industrial minerals and precious stones; the development of exchange activities in the area of the environment and the creation of a data bank of geological and mining of the countries involved in the program. This intention of working together was presented to SGT2, Theme of Geology and Mineral Resources MERCOSUR Commission, at its first meeting, held in Buenos Aires - Argentina, in April 1996, with the aim of transforming it into an official activity of this Commission, time that the delegations of the four States-Party endorsed the proposal. These opportunities were discussed and established parameters and standards for the execution of the works to be developed in the area between the parallel of 14oS and 38oS and meridians 44oW and 68oW (Figure 1), covering approximately 5,800,000 Km2 continental area, scale 1: 2,500,000, covering the entire basin of the River Plate. geological one, one and one hydrogeological mineral resources, plus a database of mineral resources, which serve as a source of information for the map of mineral resources: the generation of three maps was established as a goal. The official name for this project was established Maps
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Archivo y relato en el Río de la Plata Colonial. El difícil discurso de la violencia
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Loreley El Jaber
2013-11-01
Full Text Available La propuesta en esta ocasión es la de abordar la relación entre archivo y relato en el Río de la Plata durante el siglo XVI y, para esto, se analizará una información levantada por Cabeza de Vaca en su defensa, fechada en 1544, porque en ella se da lugar a la aparición de un conjunto de voces de españoles que denuncian los atropellos, gravámenes y “vejaciones” sufridas por parte de sus pares en procura de la cobranza del quinto. Estos discursos, no reproducidos por otros textos impresos durante el mencionado siglo, plantean una problemática compleja: la relación entre ley, violencia y espacio conquistado; pero también, otra de distinto orden: los alcances y efectos de discursividades como estas, devenires de un relato cruel detenido en el tiempo del archivo judicial. El presente trabajo busca abordar ambas problemáticas así como darle un lugar a esta serie de voces olvidadas.
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Maximiliano D. Garcia
2014-05-01
Full Text Available In this study we investigated the spatial distribution of the plankton community, bacterio-, phyto- and zooplankton, in relation with environmental conditions along the intertidal coast of the Río de la Plata estuary, Argentina. Plankton was analyzed in terms of species composition, abundance, biomass (carbon content and size-structure. We aim to evaluate the potential effects of anthropogenic impacts (e.g., nutrient enrichment and physicochemical gradients alongshore (e.g., salinity, turbidity on the composition and functioning of the plankton. We asked whether the natural structuring of the plankton by salinity and turbidity, known to be true of estuaries, is modified by eutrophication along the studied shoreline. We found that the density and biomass of bacteria and phytoplankton were strikingly enhanced by high eutrophication levels along the intertidal southwest coast of the Río de la Plata estuary. We also found that the highest zooplankton density in the most polluted area but the biomass showed a different distribution pattern. Nevertheless, when zooplankton was analyzed by means of its size fraction, we accordingly found that the microzooplankton biomass was positively associated with smaller-size phytoplankton groups and the most polluted study sites. Copepods were the major taxonomic groups that best represented the mesozooplankton biomass. We therefore expected that its distribution was modulated by the presence of its food items (i.e., large cells which, in turn, were more abundant in the middle-outer zone. In contrast, we found that the highest biomass of copepods occurred at the innermost site of the estuary and we found no significant association with other planktonic groups. Overall, this study highlights the noteworthy impacts of human activities modifying the functioning of this coastal ecosystem. The differences found in the taxonomic composition and size structure of the planktonic community assemblage between the most
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In Memoriam, En Homenaje a los Drs. Rafael Barberi Zamorano y Ernesto Plata Rueda
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Eduardo Alvarez P.
1992-09-01
Full Text Available
Y se marcharon…. Partieron como si existiera un acuerdo previo para realizar el encuentro definitivo en la eternidad. Después de una ejemplar y fructífera existencia, plena de múltiples realizaciones, se hace indispensable el goce de la paz eterna. Partieron, pese nos dejaron la huella de dos vidas que marcharon paralelamente con destino hacia un mismo objetivo, el niño colombiano.
Este ser, la razón primera de nuestra especialidad, incapaz de mentir, inocente, indiferente ante lo bueno y lo malo, indefenso, amante del mundo que lo rodea, tierno y cariñoso. Fueron dos ilustres colombianos que caminaron por el mismo sendero, con diferente fin. Ernesto Plata Rueda en el campo de la investigación y la docencia y Rafael Barberi Zamorano en la dirección y administración del Hospital de la Misericordia, cuna de la pediatría en nuestra patria y recurso en salud en favor de las clases sociales menos favorecidas.
Como extraña y feliz coincidencia el destino los ubicó a pocos metros de distancia el uno del otro, lo que facilitó para que sus labores fueran siempre acordes y se desarrollaran en perfecta armonía por cerca de tres lustros; esta circunstancia permite al final presentar a las generaciones futuras toda esa inmensa gama de realizaciones que hoy quedan en los campos de la salud y la ciencia. Tuve la inmensa fortuna de ser testigo cercano del diario desarrollo de sus actividades y es por esta razón por la cual no puedo retirar de la mente la capacidad de trabajo, dedicación y amor a los pacientes, al Hospital, de Rafael Barberi un gran filántropo, hombre tímido y sencillo, virtudes que lo hicieron más grande y admirable; no le faltó jamás el valor suficiente dentro de la mayor honestidad y respeto para convertirse en aguerrido defensor de la Institución y de sus colaboradores, también fué geperoso y bondadoso al otorgar el perdón y el olvido a sus ocasionales detractores.
Ernesto Plata Rueda, el
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Becherucci, Maria Eugenia; Seco Pon, Juan Pablo
2014-08-01
Nightlife activities represents an important source of urban litter; the latter often being left behind or abandoned in public places and streets. Mar del Plata is a very important city on the Atlantic coast of Argentina and is the main tourism destination in the South Atlantic region of South America. However, few studies on urban litter related to nightlife activities have been conducted in the area. Here we assessed (i) the abundance and composition of litter, and (ii) the spatial and temporal variations of its abundance, diversity, richness and evenness in urbanized areas with different intensity of nightlife activities from April 2008 to March 2009. An overall of 13,503 items were counted. Around 92% of the total litter was comprised by cigarette butts, papers and plastics. We found significant spatial differences in the abundance of litter between sampling sites, with the greatest amounts of litter at the Alem site followed by the Hipólito site (both with an intensive nightlife activity) compared with the Chauvin site (a quiet high-income neighborhood). The composition of litter of the Alem and the Hipólito sites was relatively similar and both sites differ with respect to the Chauvin site. Cigarette butts, papers, and plastics were the items that contributed most to the dissimilarity between sampling sites. The diversity of litter was the single community parameter that significantly differed from the other seasons. We discussed the potential effect of nightlife activities on the amounts and quality of urban litter in the city of Mar del Plata. Copyright © 2014 Elsevier Ltd. All rights reserved.
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Germán Flavio Soprano Manzo
2009-11-01
Full Text Available This article analyze two process connect in one university institution. In the first part, study the autonomy's forms of the institutional organization discipline produced for the professors and investigators of the Institute of the Museum and the Superior School/ Faculty of the Natural Sciences in the Universidad Nacional de La Plata between 1935 and 1946. In the second part, study two social situations - the university interventions of the years 1946 and 1955- where the political of the National State produced changes in the trajectories of this academics. We explore this relationship in the leadership and academics groups in geology, paleontology, zoology, botanic and anthropology.
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Guerrero Soriano, Cándido P.
1994-06-01
Full Text Available Not available.
En el siglo XVIII, el Río de la Plata se vio afectado de forma clara y contundente por la política ilustrada y racionalista de la nueva casa reinante en la metrópoli. En parte por esa acción política, y sobre todo por la fuerza de los acontecimientos, se produjeron cambios, claramente perceptibles a grandes rasgos, pero difícilmente detectables y evaluables de forma concreta. Este trabajo pretende acercarse a la realidad menos visible mediante el análisis y la interpretación de datos cruzados de fuentes de índole diversa; a saber: fuentes decimales y registros fiscales. -
Pesticide impact study in the peri-urban horticultural area of Gran La Plata, Argentina.
Mac Loughlin, Tomás M; Peluso, Leticia; Marino, Damián J G
2017-11-15
Vegetable production systems are characterized by intense pesticide use, yet the effects on the surrounding environment are largely unknown and need to be studied. Given this knowledge gap, the objective of this work is to determine the impact of horticulture on a representative watercourse by conducting an integrated study of the occurrence and concentration of pesticides in bottom sediments and their relation to lethal and sublethal effects on benthic fauna. Two sampling campaigns were conducted during seasons of low and high pesticide application in five sites along the Carnaval creek, located in the peri-urban area of La Plata City (Buenos Aires, Argentina). The samples were tested for 36 pesticide compounds by GC-MS and LC-MS, and whole-sediment laboratory toxicity tests were performed using the native amphipod Hyalella curvispina. The results showed a general but variable distribution in the concentrations detected along the stream. For each sampling campaign (first/second), the total pesticide loads, measured as the sum of herbicides, insecticides and fungicides, were 1080/2329, 3715/88, and 367/5ngg -1 dw, respectively. Lethal and sublethal effects were observed in both sampling campaigns. In order to correlate both sets of results, data were assessed by multivariate analysis, including principal component analysis. The observed toxicity was considered to be mainly due to insecticides; thus, horticultural practices have an impact on nearby watercourses and can potentially endanger the benthic fauna. This is the first study in Argentina to assess the impact of pesticides on aquatic environments close to horticultural production areas. Copyright © 2017 Elsevier B.V. All rights reserved.
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Cubillos Eliberto
2001-12-01
Full Text Available En Colombia el sector de flores de corte para exportación se
ha constituido en un renglón de gran importancia económica.
Sin embargo, los altos costos de producción y los bajos precios han hecho que la rentabilidad de esta industria haya
decaído en los últimos años. El tiosulfato de plata (STS es
uno de los productos más empleados en poscosecha de flores, pero en la actualidad es visto como un posible contaminante ambiental. Con el objetivo de comparar la respuesta de productos tradicionales en poscosecha, cuyo ingrediente principal es el ion Ag", con otros de mayor degradabilidad, se llevó a cabo un ensayo con clavel estándar de la variedad 'Nelson '. Los tallos florales fueron cosechados en cultivo bajo condiciones de invernadero en una finca comercial de la Sabana de Bogotá, seleccionados y sometidos a diferentes soluciones de poscosecha para prolongar la vida en florero. Posteriormente, se les realizó la simulación de transporte durante un periodo de diez días y, en seguida, llevados al laboratorio de Fisiología de Cultivos de la Universidad Nacional de Colombia, Sede Bogotá, en donde, se monto el ensayo para realizar las respectivas mediciones. En el laboratorio, los tallos se mantuvieron hidratados en agua destilada, en condiciones de 12 h de fotoperiodo (luz artificial de 6 a.m. a 6 p.m. y con ventilación de 30 min en las horas de la mañana para evitar la acumulación del etileno. Las condiciones ambientales promedio del laboratorio fueron de 19°C y H. R. de 75%. Los productos comerciales empleados fueron Tiosulfato de Plata (STS elaborado en la finca, l-Metilciclopropano (1-MCP, Chrysal AVB, Chrysal EVB, Florissima 125, Florissima 135 y Florissant 100. Los mejores resultados en longevidad floral se obtuvieron con la combinación de 1-MCP + Florissima 135 (22 días, Florissima 125 (21, 7 días y STS finca (21 ,5 días. Se comprobó que algunos productos que no contienen el ion Ag (Florissima 135 y -
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Deisy Krzemien
2005-01-01
Full Text Available El presente trabajo propone, a partir de datos empíricos obtenidos en un grupo de adultas mayores, una reconceptualización de las estrategias de afrontamiento evitativas, especialmente la autodistracción, destacando su valor adaptativo frente a la crisis vital que genera el proceso de envejecimiento en las mujeres. Clínicos e investigadores sugieren que el envejecimiento implica una crisis del desarrollo que afecta la adaptación vital. La literatura científica considera que existe relación entre estrategias de afrontamiento y adaptación a situaciones críticas. Mediante un diseño cuasi-experimental de tipo pretest- postest con grupo control, se evaluaron las estrategias de afrontamiento antes y después de un programa de aprendizaje social, en una muestra de sesenta mujeres ancianas, de las cuales, treinta participaron de un curso de aprendizaje social en la Universidad de Adultos Mayores de la Universidad Nacional de Mar del Plata (Mar del Plata - Argentina, y treinta no lo hicieron. Se realizó un análisis comparativo y cuantitativo de los datos. Los resultados evidencian que las mujeres que participaron del programa de aprendizaje social presentan un estilo de afrontamiento activo y adaptativo y a la vez, un uso significativo de la estrategia de autodistracción, caracterizada teóricamente como evitativa y no adaptativa. Los resultados permiten elaborar una comprensión alternativa de la estrategia de autodistracción en función del afrontamiento a los sucesos críticos de la vejez. Se propone que frente a situaciones que no constituyen un problema a resolver como el proceso de envejecimiento en particular, la autodistracción debería considerarse como una estrategia de afrontamiento que promueve una adaptación efectiva.
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Carlos Rúa
2018-03-01
Full Text Available Micro-Raman spectroscopy was used to analyze and identify pigments and determine the palette of color in wall paintings from four churches of the Colonial Period, in the Bolivian highlands. The ancient churches Santiago de Callapa, Curahuara de Carangas, NuestraSeñora de Copacabana de Andamarca and San José de Soracachi were constructed during the 17th and 18th centuries, around the important colonial Ruta de la Plata, between Potosí city and Arica harbor on the Pacific coast of South America. Most pigments used in the wall paintings correspond to inorganic minerals as well as to organic colorants. Fully chlorinated copper phthalocyanine (green, copper phthalocyanine (blue, β-naphthol (yellow and benzoimidazolone (red, were identified in the corresponding colored areas suggesting subsequent recent interventions or restorations. Ground layer materials were also characterized. The present results allow for discussion of the pictorial techniques used in the Andean highland during the colonial period and allow conservators and restorers to make important decisions regarding the type of intervention to perform in the case of these important historical and patrimonial monuments.
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Patricia M. Arenas
2011-07-01
Full Text Available En el presente trabajo se presentan los resultados de un estudio sobre tres especies de las cuales se comercializan productos considerados adaptógenos: Lepidium meyenii Walp. (Brassicaceae, "maca", Morinda citrifolia L. (Rubiaceae, "noni", y Petiveria alliacea L. (Phytolaccaceae, "pipi". Los datos provienen de estudios en Etnobotánica urbana realizados en la conurbación Buenos Aires-La Plata, se presentan los usos tradicionales de las especies, sus vías de ingreso, comercialización y difusión como suplementos dietéticos en el contexto pluricultural urbano, los modos actuales de empleo y los saberes relacionados, que forman parte del conocimiento botánico local. De este modo, se evalúan las modificaciones en los usos originalmente asignados, como consecuencia de la expansión de los productos en el marco de la globalización, y los cambios consecuentes en los patrones tradicionales de saberes, creencias y prácticas referidos a estos recursos vegetales
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Elías Rodolfo
2003-01-01
Full Text Available The polychaete composition and distribution within mussel beds were studied in order to assess organic pollution due to domestic sewage in a rocky shore of Mar del Plata (Argentina during 1997. Four stations and a control site were randomly sampled around the local effluent. Quantitative data on polychaetes, as well as sediment accumulated among mussels and its organic carbon content were measured. Polychaete distribution patterns are related to the organic matter gradient, being Capitella cf. capitata, Neanthes succinea (Frey & Leuckart, 1847 and Boccardia polybranchia (Haswell, 1885 the dominant indicator species close to the effluent. At medial distances, the cirratulids Caulleriella alata (Southern, 1914 and Cirratulus cirratus (Müller, 1776 are very important in abundance. The syllids Syllis prolixa Ehlers, 1901 and S. gracilis Grube, 1840 are distributed along the study area, but dominate at the medial stations and at the control site. The orbiniid Protoariciella uncinata Hartmann-Schröder, 1962 is subdominant at the control station.
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Freston, Emilia; Iveninato, Silvina; Vallejo, Emiliano; Riva, Alicia
2011-01-01
El presente trabajo forma parte de un proyecto de investigación más amplio cuyo fin es delimitar el contexto de recepción del psicoanálisis francés en la ciudad de La Plata en el período que se extiende desde 1966 hasta 1976. El concepto de recepción, supone que la lectura de una obra no consiste en una mera asimilación pasiva sino en un proceso que, concebido desde una perspectiva dialéctica, pone en juego una selección que realiza el lector en tanto se ve implicado su propio punto de vista....
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Carbonari, Fabiana Andrea
2010-01-01
El valor simbólico y material aportado en el proceso de construcción del paisaje urbano de la ciudad de La Plata por la inmigración italiana es preeminente durante sus primeros cincuenta años de vida –1882 a 1932-. Entonces, resulta oportuno reflexionar sobre el ejercicio independiente de la profesión de los arquitectos, ingenieros y técnicos peninsulares. En tal sentido, la metodología de trabajo propuesta consiste en el análisis de las relaciones entre el orden político, el socio-cultura...
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María de la Paz Diulio
Full Text Available Resumen El área metropolitana de La Plata representa el 1,6% de las viviendas de la Argentina. A partir del análisis del reciclado de una vivienda se construyen indicadores básicos con el fin de proponer una metodología que facilite la extrapolación, a nivel regional, del impacto que causaría un programa de eficiencia energética en viviendas. Se exponen desde el nivel micro a macro los resultados obtenidos en un contexto de carestía energética y recurrentes crisis en la oferta de combustibles y electricidad en la Argentina. La mejora en la resistencia térmica de muros y techos en todo el parque residencial de La Plata conllevaría a una reducción del 12% de la energía consumida en calefacción, y un ahorro de 30.000 TEP/año. Se concluye que la incidencia que implica la colocación de aislación adicional respecto del costo de la construcción justifica su uso, resolviendo parcialmente la falta de combustibles en el país, reduciendo gastos fijos en la vivienda, otorgando confort térmico a los usuarios y generando reactivación del sector de la construcción.
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Eduardo Méndez
2009-07-01
Full Text Available La biodiversidad de la flora de la vertiente oriental del Cordón del Plata, Luján de Cuyo, Mendoza, Argentina se analizó a lo largo de un gradiente altitudinal, entre los 1200 y 4500 m s.n.m. Para ello se utilizó la lista florística de las especies de 89 comunidades vegetales distribuidas en 14 unidades de vegetación, 5 pisos de vegetación y 3 unidades fitogeográficas. Para cada especie se consideró su distribución en los grupos de comunidades vegetales, ubicación fitogeográfica, formas de vida, origen y registro de colección. La flora examinada contiene 667 especies vegetales que se corresponden con 338 géneros y 82 familias. Las familias están representadas por 8 Pteridophyta, 1 Gymnospermae y 73 Angiospermae, con 12 Monocotyledoneae y 61 Dicotyledoneae. Las familias mejor representadas son Asteraceae y Poaceae que tienen en conjunto 110 géneros y 249 especies. Los géneros Senecio, Baccharis y Adesmia son los más ricos en especies. Aproximadamente el 20 % de las especies son endémicas de Argentina. La flora del área se la compara con la del país, la provincia y la de otras áreas.Floristic catalogue. The floristic biodiversity of the eastern slope of the Cordón del Plata, Luján de Cuyo, Mendoza, Argentina, was studied along an altitudinal gradient, between 1200 and 4500 m a.s.l. For this we used a floristic list of 89 plant communities, distributed in 14 vegetation types, 5 vegetation belts and 3 phytogeographic units. For each of the species, its distribution in the groups of plant communities, phytogeographic position, life form, biogeographical origin, and registration of each collection was considered. The studied flora has 667 species, corresponding to 338 genera and 82 families. There are 8 Pteridophyta, 1 Gymnospermae, and 73 Angiospermae, of which 12 are Monocotyledons and 61 Dicotyledons. The most represented families are Asteraceae and Poaceae, which in total have 110 genera and 249 species. The most species
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International Nuclear Information System (INIS)
Gaucher, C.; Poire, D.G.; Pamoukaghlian, K.; Gomez Peral, L.; Finney, S.; Valencia, V.; Blanco, G.
2007-01-01
We report U-Pb ages of detrital zircons from samples of five Neoproterozoic sandstone units deposited on the Rio de la Plata Craton (RPC) in Uruguay and Argentina. Quartz-arenites of the Piedras de Afilar Formation show typical Transamazonian ages, with peaks at 2.00-2.07, 1.87 and 1.78 Ga. However, the most important zircon population is Mesoproterozoic, showing maxima at 1.49, 1.35, 1.25 and 1.0 Ga. Zircons recovered from two sandstone levels in the Arroyo del Soldado Group (Yerbal and Cerros San Francisco formations) are mostly Archean in age, with maxima at 3.2 and 2.7 Ga. Palaeoproterozoic zircons are also prominent in this unit, with peaks at 2.45 and 2.18, with the latter a typical Transamazonian age. Two samples from the Sierras Bayas Group in Tandilia (Argentina) show different age spectra. Sandstones of the Villa Monica Formation show a unimodal zircon population of Transamazonian age (peak at 2.13 Ga). Sandstones of the Cerro Largo Formation are characterized by a dominant Transamazonian zircon population (peaks at 2.15, 2.0 and 1.79), but also important Archean-lowermost Palaeoproterozoic (3.33, 2.99, 2.7, 2.47 Ga) and Mesoproterozoic peaks (1.55, 1.23 and 1.06). The abundance of Mesoproterozoic detrital zircons is surprising. A proto-Andean, Mesoproterozoic belt is suggested as the source of the Mesoproterozoic detritus. Archean rocks of the RPC crop out only in the Nico Perez Terrane in Uruguay, suggesting that the Nico Perez Terrane was much closer to Tandilia than it is today. The sinistral reactivation of the Sarandi del Yi Shear Zone in the Cambrian, as a result of tangential collision of the Cuchilla Dionisio-Pelotas Terrane, may explain this observations. The absence of Neoproterozoic zircons shows that the studied units were deposited in a stable continental margin opening to the East and South. These Neoproterozoic basins had obviously no contribution whatsoever from Brasiliano-Pan African belts, supporting the idea of Cambrian terrane
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Bronces y plata tartéssicos de Alhonoz y su hinterland
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Luis Alberto LÓPEZ PALOMO
2009-12-01
Full Text Available RESUMEN: En este artículo se ofrece una síntesis de los objetos metálicos obtenidos en las excavaciones del yacimiento sevillano de Alhonoz a lo largo de las campañas de 1973-75, 1977 y 1978 y se hace mención de otros hallazgos localizados casualmente a orillas del río Genil, entre el yacimiento de Alhonoz y el de Los Castellares (término de Puente Genil, provincia de Córdoba. Las piezas halladas en Alhonoz son: un thymaterion de bronce, no completo, de tipo chipriota, idéntico al que el profesor Karageorghis da a conocer procedente de Angolemi, dentro del tipo B-2 de la sistematización de Almagro Gorbea, que lo fecha hacia el siglo VII-VI a. C , una pequeña figurilla de la diosa Minerva y otros pequeños objetos también broncíneos, de las mismas excavaciones. Se publica también en este artículo un exvoto de plata, muy interesante, que ha sido calificado como «los ojos de Astarté» y que tiene muchas resonancias en el mundo fenicio. Por último se publican otros objetos de bronce procedentes de diferentes lugares cercanos a Alhonoz, y del mismo ambiente arqueológico.ABSTRACT: In this article a synthesis is offered of the metalics objets obtained at the excavations of the Sevillian deposit of Alhonoz during the 1973-75, 1977 and 1978 campaings. And another discovery is mentioned, casually found by the Genii riverside, between the deposits of Alhonoz and Los Castellares (municipal district of Puente Genii, Córdoba province. The pieces discovered at Alhonoz are: an incomplete bronze thymaterion of a Cypriot type, identical to the one made known by profesor Karageorghis, coming from the type B-2 of Almagro Gorbea systematization, which he dates at about the seventh-sixth centuries B.C., a little figure of Minerva goddess, and some other objecrs, also bronzed, from the same excavations. It is also published, in this article, a very interesting silver Ex-voro which has been qualified. Lastly, other bronze objets are published from
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Gastón Julián Gil
2007-11-01
Full Text Available It is widely accepted that during the last military dictatorship in Argentina, human and social sciences were privileged focus of ideological persecution and governmental attacks. Nevertheless, these serious persecutions and attacks did not begin with the coup d'etat of March 24 of 1976. Almost two years before, during the presidency of María Estela Martínez, Argentinean universities were specially chosen by para-governmental terrorism, which was symbolized by the infamous Minister of Welfare, José López Rega, as places to develop its criminal actions. As a particular case, the School of Anthropology at the University of Mar del Plata suffered a dramatic process of dismantlemenjt from the middle of 1974 to the end of 1975, when all the applications for the School of Anthropology were cancelled. Drawing both on official documents of the university and on testimonies of people who were engaged in that experience, in this article I aim at accounting for a historical context which laid the foundations of a tragic path that was going to be continued by the military process.
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Claudia Nora Laudano
2011-06-01
Full Text Available Este trabajo indaga los modos de abordaje de la cuestión tecnológica en la formación profesional universitaria en Bibliotecología desde una mirada histórica que abarca 30 años. El estudio toma por caso la Carrera de Bibliotecología de la Facultad de Humanidades y Ciencias de la Educación de la Universidad Nacional de La Plata (Argentina y considera centrales las transformaciones curriculares en el área de tecnología. Para el abordaje metodológico se contempló, por una parte, el análisis documental de los planes de estudios, los programas de algunas asignaturas y otros materiales significativos. Por otra parte, se entrevistaron docentes que intervinieron en las modificaciones del currículo en los últimos 30 años. Del análisis de ambos materiales surgen tendencias coincidentes respecto del lugar de lo tecnológico en la formación profesional así como sugerencias acerca de posibles modificaciones en la enseñanza.This paper inquires how the technological question is approached in the university professional training in librarianship, in an historical overview which covers 30 years. It is a case study of the librarianship degree in the Facultad de Humanidades y Ciencias de la Educación de la Universidad Nacional de La Plata and the curricular transformations in the technological area are of key importance. The methodological approach is focused in the documental analysis of the curricula, the programs of some subjects and other significant materials. Also, some teachers responsible of the changes in the curriculum during the last 30 years were interviewed. From the analysis of both materials is possible to deduce coincident tendencies about the technology place in the professional training, as well as suggestions about possible modifications in the teaching of librarianship.
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María Inés Lorenzo
2011-03-01
Full Text Available Demersal fish assemblages from trawl surveys in the Rio de la Plata estuary and its inner continental shelf were analyzed from 1975 to 1995. The first two factors of Principal Component Analysis explained 48% of the variance in species distribution, and they are consistent with the results of a cluster analysis. The analysis indicated the existence of three spatially and temporally distinct fish assemblages: internal and external estuarine and inner continental shelf (Uruguayan coastal assemblages. These assemblages were persistent considering the environmental characteristics and their species composition. Despite the changes registered in the species density during the period surveyed, the fish assemblages tend to persist over time. It was demonstrated that the assemblages can be considered as open systems and that there exists a reciprocal flow of organisms between adjacent associations. However, each assemblage showed high spatial and temporal persistence in accordance with the environmental characteristics of the system analyzed. Therefore, and according to the multispecies fisheries operating in the system, each assemblage defined could be considered a unit of management.Foram analisadas as associações dos peixes demersais provenientes de arrastos de prospecção no estuário do Rio de la Plata e sua plataforma interna no período de 1975 a 1995. Os dois primeiros fatores da Análise de Componentes Principais explicaram 48% da variância na distribuição das espécies sendo consistentes com os resultados da análise de agrupamento. Os resultados mostraram a existência de três associações de peixes espacial e temporalmente distintas: uruguaia costeira, estuarina externa e estuarina interna. Essas associações foram consistentes quanto às características ambientais e de composição de espécies. A despeito das mudanças registradas na densidade das espécies ao longo do período analisado, as associações de peixes foram
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8th Argentinean Bioengineering Society Conference (SABI 2011) and 7th Clinical Engineering Meeting
Meschino, Gustavo Javier; Ballarin, Virginia L.
2011-12-01
In September 2011, the Eighteenth Edition of the Argentinean Bioengineering Society Conference (SABI 2011) and Seventh Clinical Engineering Meeting were held in Mar del Plata, Argetina. The Mar del Plata SABI Regional and the School of Engineering of the Universidad Nacional de Mar del Plata invited All bioengineers, engineers, physicists, mathematicians, biologists, physicians and health professionals working in the field of Bioengineering to participate in this event. The overall objectives of the Conference were: To provide discussion of scientific research results in Bioengineering and Clinical Engineering. To promote technological development experiences. To strengthen the institutional and scientific communication links in the area of Bioengineering, mainly between Universities of Latin America. To encourage students, teachers, researchers and professionals to establish exchanges of experiences and knowledge. To provide biomedical engineering technology solutions to the society and contributing ideas for low cost care. Conference photograph Conference photograph Conference photograph Conference photograph EXECUTIVE COMMITTEE SABI 2011 Chair Dra Virginia L Ballarin Universidad Nacional de Mar del Plata Co-Chair Dra Teresita R Cuadrado Universidad Nacional de Mar del Plata - CONICET Local Comittee Dr Gustavo Abraham Universidad Nacional de Mar del Plata - CONICET Dra Josefina Ballarre Universidad Nacional de Mar del Plata - CONICET Dr Eduardo Blotta Universidad Nacional de Mar del Plata Dra Agustina Bouchet Universidad Nacional de Mar del Plata Dr Marcel Brun Universidad Nacional de Mar del Plata Dra Silvia Ceré Universidad Nacional de Mar del Plata - CONICET Dra Mariela Azul Gonzalez Universidad Nacional de Mar del Plata - CONICET Dra Lucia Isabel Passoni Universidad Nacional de Mar del Plata Dr Juan Ignacio Pastore Universidad Nacional de Mar del Plata - CONICET Dra Adriana Scandurra Universidad Nacional de Mar del Plata SCIENTIFIC ADVISORY COMMITTEE
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Garavaglia, Juan Carlos
2004-08-01
Full Text Available Following the track of a number of studies on the early forms of representation in Iberian America, we will show how a detailed anaylisis of the first elections in the Rio de la Plata may contribute to widen our knowledge of «political representation» and «citizenship» during the two first revolutionary years. Setting off from the vacatio regis, it will be analysed in which way the Buenos Aires elites made efforts to keep the independent process under control. While this aim was achieved, the price paid for it would entangle serious consequences for the later evolution of the Rio de la Plata area.
Siguiendo el camino trazado por una serie de estudios sobre historia de las formas primigenias de representación en América ibérica, trataremos de mostrar de qué forma un análisis pormenorizado de primeras elecciones rioplatenses puede contribuir a enriquecer nuestro acercamiento al tema de la «representación política» y de la «ciudadanía» durante los dos años iniciales post revolucionarios. Partiendo evidentemente de la «vacatio regis», tratamos de ver en este trabajo de qué modo las elites de Buenos Aires, que estaban conduciendo el único proceso que se mantuvo en forma independiente durante ese periodo, hicieron todo lo posible para que éste no escapara a su control. Efectivamente, lo consiguieron pero, a un precio que acarrearía graves consecuencias en la evolución posterior del área rioplatense. -
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Gavira Márquez, María Concepción
2001-08-01
Full Text Available This article analyzes the relation between silver production and the internal market in the mining region of Oruro at the end of the 18th century. On the basis of different complementary sources, including fiscal accounts, a hypothesis is presented to explain the problem posed by an increase in values from alcabalas during a period of mining crisis.
En este trabajo se analiza la relación entre la producción de plata y el mercado interior en la región minera de Oruro a fines del siglo XVIII. Partiendo del estudio de diferentes fuentes complementarias, entre ellas las fiscales, se pretende explicar la problemática que plantea una subida de las alcabalas en un período de crisis minera.
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Soledad Lemmi
2011-01-01
Full Text Available This article provides a characterization of the social relations that prevail in vegetable production in La Plata. The work is based on the tenets of Marxism, which are used for understanding and description of the society. In the first section, a brief theoretical description of the capitalist logic of production is made following the historical materialism methodology, and proposed a designation of the subject of horticulture in the classic formulation of Marxism to capitalist social relations: landowners, bourgeois and salaried. Then empirical data is displayed on the sector that accounts of the historical formation of social classes in it. This information emerges from the analysis and study of the historical shape of La Plata horticultural land, the 1998 and 2005 horticultural census results, the confrontation and conflict register brought on by the different subjects of production over the last 50 years and ends with several contributions arising from oral histories taken from interviews. Finally, some conclusions are systematized.En este artículo se realiza una caracterización de las relaciones sociales que priman en la producción de hortalizas en La Plata. El trabajo parte de los postulados del marxismo para el entendimiento y descripción de la sociedad. En el primer apartado se realiza una breve descripción teórica de la lógica capitalista de producción siguiendo la metodología del materialismo histórico y se propone una denominación de los sujetos de la horticultura bajo la formulación clásica del marxismo para las relaciones sociales capitalistas: terratenientes, burguesía y asalariados. Luego se despliega información empírica sobre el sector que da cuenta de la conformación histórica de las clases sociales en el mismo. Esta información surge del análisis y estudio de la conformación histórica del territorio hortícola platense, los resultados de los censos hortícolas de 1998 y 2005, del registro de los
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Sanmartino, Mariana; Amieva, Carolina; Medone, Y Paula
2017-03-01
Hablar de Chagas es hablar de una problemática compleja, definida por elementos de carácter biomédico, epidemiológico, sociocultural y político, que se conjugan dinámicamente. En este trabajo buscamos identificar y analizar las representaciones sobre Chagas de los integrantes del equipo de salud de un centro de atención periurbano de la ciudad de La Plata, Argentina. Mediante un abordaje cualitativo, se realizaron entrevistas semiestructuradas y se analizaron las respuestas con la técnica del análisis de contenido. Los resultados mostraron que la mayor parte de las personas entrevistadas no contempla al Chagas como una problemática en su contexto laboral cotidiano y manifiestan un fuerte sesgo biologicista en su formación profesional. Con este trabajo señalamos la urgente necesidad de reflexionar críticamente en torno a la formación de los profesionales de la salud en relación a problemáticas socioambientales complejas de importancia regional, como lo es el Chagas.
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Antonio J. Palacios García
2009-01-01
Full Text Available En las ciudades españolas todavía persisten un buen número de áreas que presentan una serie de carencias urbanísticas, sociales, económicas, ambientales u otras. Es lo que se conoce como barrios desfavorecidos urbanos. Para esta aportación se analiza el caso de una zona del sur metropolitano madrileño como es la de Plata y Castañar. En dicho barrio vamos a tratar de desentrañar el proceso de sustitución y creación de la edificación existente, los problemas acontecidos durante el desarrollo de la intervención, sus dificultades y las herramientas empleadas. Un área donde se ha intervenido frente al desfavorecimiento de forma sectorial, sobre un único elemento, el espacio construido. Aún a costa de la persistencia en el tiempo de otras graves carencias (fundamentalmente de tipo social. Una forma de intervenir muy criticada por cuanto supone la agrupación en un mismo territorio de una población desfavorecida.
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International Nuclear Information System (INIS)
Preciozzi, F.; Peel, E.; Sanchez, L.; Basei, M.
2005-01-01
U-Pb zircon ages between 1000 and 900 Ma corresponding to the nuclei of zircon crystals extracted from the basement of the Punta del Este Terrane (Eastern Uruguay) allowed the correlation of the protoliths of this domain with rocks attributed to the Namaqua Belt in Southwestern Africa. SHRIMP ages obtained for the ortho gneissic rocks allowed to place at ca. 750 Ma the generations of gneisses and migmatites. Differently from what occurred in Africa, reworking of this crustal segment during the Brasiliano-Pan african orogenesis was very intense, reaching the granulite facies around 640Ma. Acid volcanic and volcaniclastic rocks (Sierra de Aguirre Formation) with ages around 570 Ma, late sedimentary basins (San Carlos Formation) and post-tectonic granitoids (Santa Teresa and José Ignacio batholith s) mark the end of the events related with the Brasiliano/Pan-African orogenesis. The final collision between the Punta del Este Terrane and the western domains represented by the Dom Feliciano Belt and the Río de La Plata Craton may have occurred at around 535 Ma
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Malleville, Sofía
2017-01-01
La presente tesina analiza la configuración de las condiciones laborales y su relación con el proceso salud-enfermedad de los trabajadores y trabajadoras de una clínica de medicina privada ubicada en el casco urbano de la ciudad de La Plata, durante el año 2016. Dicha institución se inscribe en el complejo entramado que reviste el sistema de salud en nuestro país, caracterizado por su escaza articulación y elevada segmentación. A su vez, la clínica privada posee una serie de particularidades ...
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Elisangela Bellafronte
Full Text Available In the past years, DNA barcoding has emerged as a quick, accurate and efficient tool to identify species. Considering the difficulty in identifying some Parodontidae species from the La Plata basin and the absence of molecular data for the group, we aimed to test the effectiveness of DNA barcoding and discuss the importance of using different approaches to solve taxonomic problems. Eight species were analyzed with partial sequences of Cytochrome c oxidase I. The mean intraspecific K2P genetic distance was 0.04% compared to 4.2% for mean interspecific K2P genetic distance. The analyses of distance showed two pairs of species with K2P genetic divergence lower than 2%, but enough to separate these species. Apareiodon sp. and A. ibitiensis, considered as the same species by some authors, showed 4.2% genetic divergence, reinforcing their are different species. Samples of A. affinis from the Uruguay and Paraguay rivers presented 0.3% genetic divergence, indicating a close relationship between them. However, these samples diverged 6.1% from the samples of the upper Paraná River, indicating that the latter represents a potentially new species. The results showed the effectiveness of the DNA barcoding method in identifying the analyzed species, which, together with the morphological and cytogenetic available data, help species identification.
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Seroprevalencia de babesiosis bovina en la hacienda Vegas de la Clara, Gómez Plata (Antioquia, 2008
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Richard Zapata Salas
2011-06-01
Full Text Available La babesiosis es una enfermedad del ganado bovino transmitida por la garrapata Rhipicephalus (Boophilus microplus y causada por los parásitos protozoarios Babesia bovis y B. bigemina. Una zona se considera epizootiológicamente estable frente a Babesia spp, cuando el 75% de los bovinos entre las edades de 3 a 9 meses son serorreactivos (IgG frente a Babesia bovis y Babesia bigemina y no hay evidencia de signos clínicos. El objetivo de esta investigación fue determinar la seroprevalencia de Babesia bovis y Babesia bigemina en el ganado bovino de la hacienda Vegas de la Clara (Universidad de Antioquia, Gómez Plata, Antioquia, por medio de inmunofluorescencia indirecta. Se diseñó un estudio descriptivo prospectivo con análisis de corte transversal. Fue evaluada toda la población bovina de la hacienda Vegas de la Clara (n = 118. Las muestras fueron evaluadas por inmunofluorescencia indirecta para la detección de anticuerpos tipo IgG específicos contra Babesia bovis y B. bigemina. La serorreactividad obtenida en los bovinos evaluados, para al menos una especie de Babesia fue del 89,8%, para Babesia bovis del 83,8%, mientras que para B. bigemina del 61%. Se obtuvo una relación estadísticamente significativa entre la serorreactividad para B. bigemina y la frecuencia del tratamiento garrapaticida. La serorreactividad indica estabilidad enzoótica en el hato para B. bovis, mientras que para B. bigemina se encontró que la frecuencia del tratamiento garrapaticida interrumpe su ciclo de transmisión.
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Ion-ion collisions and ion storage rings
International Nuclear Information System (INIS)
Mowat, J.R.
1988-01-01
Improved understanding of fundamental ion-ion interactions is expected to emerge from research carried out with ion storage rings. In this short survey the significant advantages and unique features that make stored ions useful targets for collision experiments are reviewed and discussed. It is pointed out that improvements to existing ion-ion experiments, as well as qualitatively new experiments, should occur over the next few years as ion storage rings become available for atomic physics. Some new experiments are suggested which are difficult if not impossible with present-day technology, but which seem feasible at storage rings facilities. (orig.)
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FramiñAn, Mariana B.; Valle-Levinson, Arnoldo; Sepúlveda, HéCtor H.; Brown, Otis B.
2008-08-01
Intratidal variability of density and velocity fields is investigated at the turbidity front of the Río de la Plata Estuary, South America. Current velocity and temperature-salinity profiles collected in August 1999 along a repeated transect crossing the front are analyzed. Horizontal and vertical gradients, stability of the front, convergence zones, and transverse flow associated to the frontal boundary are described. Strong horizontal convergence of the across-front velocity and build up of along-front velocity shear were observed at the front. In the proximity of the front, enhanced transverse (or along-front) flow created jet-like structures at the surface and near the bottom flowing in opposite directions. These structures persisted throughout the tidal cycle and were advected upstream (downstream) by the flood (ebb) current through a distance of ˜10 km. During peak flood, the upper layer flow reversed from its predominant downstream direction and upstreamflow occupied the entire water column; outside the peak flood, two-layer estuarine circulation dominated. Changes in density field were observed in response to tidal straining, tidal advection, and wind-induced mixing, but stratification remained throughout the tidal cycle. This work demonstrates the large spatial variability of the velocity field at the turbidity front; it provides evidence of enhanced transverse circulation along the frontal boundary; and reveals the importance of advective and frictional intratidal processes in the dynamics of the central part of the estuary.
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Experimental use of Land Surface Models in the La Plata Basin
Goncalves, L.; de Mattos, J. Z.; Sapucci, L. F.; Herdies, D. L.; Berbery, E. H.
2009-12-01
Soil moisture is a key variable that controls the partitioning between sensible and latent heat flux, and under favorable conditions, it can modulate precipitation. The overlying boundary layer can be affected by soil moisture anomalies when persisting for an enough period of time. Several studies have shown the influence of surface processes in the South American atmospheric circulation and precipitation patterns. However the absence of a comprehensive observation network over that region represents a disadvantage for determining and quantifying memory and coupling between the land surface and the atmosphere. The La Plata Basin (LPB) in southeastern South America is recognized as an area of great importance for the economic and social development of several countries. Vast areas of this basin have experienced changes in land cover conditions due to the expansion of the agriculture (replacing natural vegetation), but also due to changes in crop types. This work presents results from an ensemble of four land surface models (Noah, CLM, MOSAIC and SiB2) used for climatic characterization of the past 30 years of soil moisture and temperature over the LPB. The Modern Era Retrospective-Analysis for Research and Applications (MERRA), from NASA’s Global Modeling and Assimilation Office (GMAO) was downscaled to be used to force the land surface models at 10Km, 3-hourly resolutions. Two sets of runs were made for this study: first, the LSMs were forced using reanalysis data to characterize the climatological states at coarse resolution, and second, the models were run using South American LDAS forcing fields from 2000 until present at higher resolution. The resulting spread among the different models was used as a measure of uncertainty in the initial states. In particular, the surface states derived from the Noah model were rescaled and used as initial conditions for atmospheric model simulations using the coupled ETA/Noah models. The control run was performed using
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La estructuración del comercio y la navegación desde el río de la Plata a Cuba
Directory of Open Access Journals (Sweden)
Asdrúbal Silva, Hernán
1994-12-01
Full Text Available Not available.
El presente trabajo tiene por objeto estudiar la estructuración del tráfico y las exportaciones desde el Río de la Plata a La Habana, teniendo en cuenta básicamente la conjunción de tres factores: a el desenvolvimiento de la industria saladeril rioplatense, que hizo de las carnes el elemento esencial de exportación hacia La Habana, b la expansión del sistema esclavista y la transformación productiva cubana, que generó un interesante mercado, c la rápida conformación de una estructura de comercialización y transporte. Aspectos tales como los vinculados a la producción regional y el establecimiento de los nexos comerciales, el movimiento marítimo y las variantes en la navegación, la significativa presencia de catalanes y norteamericanos en el tráfico, los volúmenes de las principales exportaciones, etc., adquieren significación dentro del proceso histórico que les toca vivir a las posesiones hispanas desde fines del siglo XVIII hasta la Revolución independentista. -
Bernardi, Ricardo
2002-08-01
Controversies are part of the process of scientific knowing. In psychoanalysis, the diversity of theoretical, technical and epistemological positions makes the debate particularly necessary and by the same token difficult. In this paper, the author examines the function of controversies and the obstacles to their development, taking as examples the debates held in the Río de la Plata (Buenos Aires and Montevideo) during the nineteen seventies, when the dominant Kleinian ideas came into contact with Lacanian thought. The author examines different examples of argumentative discourses, using concepts taken from the theory of argumentation. The major difficulties encountered did not hinge on characteristics pertaining to psychoanalytic theories (i.e. the lack of commensurability between them), but on the defensive strategies aimed at keeping each theory's premises safe from the opposing party's arguments. A true debate implies the construction of a shared argumentative field that makes it possible to lay out the different positions and see some interaction between them and is guided by the search for the best argument. When this occurs, controversies promote the discipline's development, even when they fail to reach any consensus.
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Lauretta, Daniel; Penchaszadeh, Pablo E.
2017-10-01
The black coral Dendrobathypathes grandis (Cnidaria: Antipatharia) is studied for the first time in the southwestern Atlantic off Argentina. This is the only antipatharian reported from the Atlantic between 35°S and 54°S. Eleven specimens were collected at depths of 819-2204 m during three expeditions to the Mar del Plata submarine canyon (2012-2013); seven were females. The species is gonochoric, and the polyps in female colonies contain up to nine oocytes per polyp, which can reach 1500 μm in diameter. In contrast, the largest oocyte currently reported for antipatharians is 500 μm, and usual diameters do not exceed 200 μm. These large oocytes have over 20 times more volume than the biggest oocyte reported, but over 800 times more volume when compared with the common oocyte size of the group. Sperm size and morphology is similar to previous data from other species. As in previous studies, neither embryos nor larvae were found in any specimens. This species was previously only reported from waters off South Georgia Island, and so these specimens expand the known distribution north by 1800 km.
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Contribución a la identificación de esporas del Reino Fungi en la atmósfera de La Plata, Argentina
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Daniela S. Nitiu
2010-12-01
Full Text Available A partir del análisis del registro aeromicológico de la ciudad de La Plata se propone la definición de Grupos Morfológicos de esporas del Reino Fungi. Este estudio constituye un aporte metodológico a la identificación y recuento de una fracción de la micobiota atmosférica. Para la definición de los grupos, se han tenido en cuenta los criterios de Saccardo (1886 y reformulado los agrupamientos de Díaz et al. (1998 y Aira et al. (2005. Se han creando 4 nuevos grupos y se han incorporando otros tipos esporales a las clasificaciones previas. Cada grupo, incluye entre 2 y 6 tipos de esporas pertenecientes a los Phylum Zygomycota, Basidiomycota y Ascomycota y sus anamorfos, que han sido asignados a nivel genérico. Los caracteres que definen dichas asociaciones son: Grupo Absidia, amerosporas hialinas; Grupo Cortinarius, amerosporas pigmentadas amigdaliformes; Grupo Didymella, didimosporas hialinas o levemente coloreadas; Grupo Didymosphaeria, didimosporas y didimoconidios pigmentados; Grupo Lepthosphaeria, fragmosporas septadas hialinas a pigmentadas y Grupo Helminthosporium, fragmosporas distoseptadas hialinas a pigmentadas. Esta investigación aspira a proporcionar una herramienta que facilite el procesamiento de datos y aporte nuevos elementos cualitativos a las clasificaciones previas, contribuyendo en la compleja problemática de identificación de las esporas fúngicas.Based on the aeromycological analysis of La Plata city, artificial Morphological Groups of fungal spores were defined. This study is a methodological contribution to the identification and counting of a fraction of the atmospheric micobiota. For the definition of groups, the criteria of Saccardo (1886 were taken into account and the groupings created by Díaz et al. (1998 and Aira et al. (2005 have been reformulated. Four new groups have been created and other sporal types have been incorporated to previous classifications. Each of them includes 2 to 6 spore types
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Directory of Open Access Journals (Sweden)
Federico González
2016-12-01
Full Text Available Desde la perspectiva espacial, el presente artículo tiene como objetivo analizar cómo dos espacios, con tradiciones e historias distintas, son transformados por las mediaciones de una política pública y por el trabajo cotidiano que militantes de dos organizaciones llevan a cabo en los barrios donde se encuentran insertos. De esta forma, se intenta contribuir a las discusiones en torno a las relaciones entre espacio y política en el caso de la experiencia de una política pública de terminalidad educativa: el Plan FinEs2. Para ello, trabajamos a partir de dos investigaciones que desde una perspectiva cualitativa analizan las experiencias del Plan FinEs2 en dos barrios de la ciudad de La Plata. Como resultado, pudimos observar las formas en que estos dos espacios son transformados a partir de las relaciones tejidas entre la política, lo educativo y lo espacial.
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Vela Romero, Lourdes Amparo
2012-01-01
El uso de nanomateriales en productos de consumo diario está incrementándose rápidamente. Por lo tanto, dadas las propiedades de las nanopartículas, su exposición puede representar un riesgo para la salud de los trabajadores de la industria y de la población en general. Entre los nanomateriales, debido a su capacidad antimicrobiana, las nanopartículas de plata muestran un gran potencial en las aplicaciones médicas y así su uso cada vez más extendido. Dada la escasa información existente...
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Mirta L García
2010-01-01
Full Text Available The spatial pattern of fish assemblages and its relationship with factors along an environment gradient, from fresh to marine water environment along the Río de la Plata estuary (36ºS, 56ºW the shelf and part of the slope, was examined using data from 22 sampling stations. Fish were sampled from all station with an Engel type trawl (200 mm stretched mesh in the wings, 120 mm stretched mesh in the cod ends, 4 m vertical opening and 15 m horizontal aperture towed at 4 knots for 20 to 30 min per set. Cluster analysis and ordination analysis MDS were used to define spatial distribution of fish assemblages based on fish composition (abundance and biomass. BIO-ENV process was used to estimate assemblage association with depth, temperature and salinity of surface and bottom waters. The results of these analyses showed that the fish community along the riverine-marine gradient was structured in four assemblages: riverine, estuarine, shelf and slope. These assemblages were found to differ significantly in their species composition. Each assemblage was characterized by several common and discriminator species and characterized by differing environmental conditions. Bottom salinity and bottom temperature were the environmental variables most strongly associated with differences in assemblage structure across the various areas. The changes in assemblage structure between areas were gradual, with no sharp boundaries.Se analizó el patrón espacial de las asociaciones de peces y su relación con los factores ambientales a lo largo del gradiente desde el agua dulce en el Río de la Plata hasta la parte superior del talud. Los peces fueron muestreados en 22 estaciones con una red de arrastre de fondo tipo Engel (200 mm de abertura de malla en las alas, 120 en el copo, 4 m de abertura vertical y 15 m de abertura horizontal con una velocidad de arrastre de 4 nudos durante 20 a 30 min. Para definir la distribución espacial de las asociaciones de peces basadas
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Distribución espacial de las parasitosis intestinales en la ciudad de La Plata, Argentina
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María I Gamboa
2014-10-01
Full Text Available El análisis de las parasitosis a diferentes escalas (regional, local se facilita por el Geographic Information System (GIS, que permite identificar áreas con distinto grado de vulnerabilidad. El objetivo del trabajo fue analizar la distribución espacial de las parasitosis intestinales en el partido de La Plata, estableciendo su relación con las condiciones socio-ambientales para identificar áreas con diferente riesgo epidemiológico. Se completó una encuesta epidemiológica y se tomaron muestras seriadas de materia fecal, analizadas por la técnica de Ritchie. Se calcularon niveles de precariedad y vulnerabilidad (Iv, y se compararon con los resultados parasitológicos. Se analizaron parasitológica y ambientalmente 653 personas, de las cuales 585 (89.6% eran niños y 68 (10.4% adultos. El análisis indicó que los más vulnerables (Iv = 3-4 estaban en el sector con menor acceso a servicios de infraestructura urbana. El índice se encontró fuertemente asociado a la prevalencia total de parasitosis intestinales y a las 4 especies patógenas asociadas a la contaminación fecal del ambiente: Trichuris trichiura, Ascaris lumbricoides, Hymenolepis nana y Giardia lamblia (p < 0.01. Enterobius vermicularis, parásito no vinculado a la condición sanitaria de sus hospedadores, no se asoció al Iv. Hubo asociación estadística entre precariedad y parasitosis y se halló que a mayor Iv mayor frecuencia de parasitosis (p < 0.01. El uso de GIS permitió zonificar las variables socioambientales en un gradiente creciente de condiciones desfavorables y su relación con la presencia de especies patógenas. La continuidad de estos estudios en diferentes regiones de Argentina contribuye a la determinación de áreas en riesgo sanitario.
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Cicalese, Guillermo
2001-01-01
La década del 80 significó para la Argentina la vuelta al sistema democrático luego de siete años de dictadura militar. Mar del Plata como el "balneario nacional" de la Argentina no escapó a los impactos sociales del modelo aperturista de la dictadura y al iniciarse la década se hacía sentir una crisis económica que sólo había sido paleada en parte por las inversiones públicas. Los cuantiosos fondos habían llegado para preparar la ciudad como sede del Mundial de Fútbol Internacional en 1978, ...
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María Cecilia Corda
2013-10-01
Full Text Available Este trabajo descriptivo exploratorio se propone analizar la arquitectura de información (AI de sitios Web de bibliotecas de la Universidad Nacional de La Plata (UNLP, Argentina. Se analizaron 17 bibliotecas y se aplicó una grilla para recabar 10 aspectos relevantes. Los resultados fueron: 1. Ubicación del sitio Web de la biblioteca: 9 sitios incluidos en la página principal de la facultad. 2. Etiquetado de contenidos: terminología simple, sin jergas; no hay homogeneidad entre las bibliotecas. 3. Capacidad de búsqueda: 62% positiva, 38% negativa. 4. Sistema de búsqueda: simple 43%, compleja 10%, con ayudas 10%, ninguno 38%. 5. Sistemas de navegación: globales 5%, jerárquicos 79%, locales 5%, ninguno 11%. 6. Herramientas de navegación: barras 16%, frames o marcos 30%, índices 2%, mapas de sitio 7%, menús horizontales 9%, menús verticales 35%. 7. Sindicación de contenidos RSS: 3 sitios. 8. Otros servicios: chat 7%, descarga de documentos 16%, envío de formularios 14%, instructivos 21%, links a otras páginas 23%, tutoriales 5%, otros 14%. 9. Accesibilidad Web: 1 sitio. 10. Otras observaciones: ninguna. Se concluye que el desarrollo de los sitios es dispar y se recomienda considerar pautas de AI como parte de la cooperación en la red de bibliotecas de la UNLP.
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Directory of Open Access Journals (Sweden)
Fernando G. Spaccesi
2012-01-01
Full Text Available The structure and composition of benthic communities on hard substrates covered by the nonindigenous bivalve Limnoperna fortunei Dunker, the golden mussel, were quantified in the middle zone of the Río de la Plata Estuary (Argentina from April 2001 through March 2002. A total of 26 taxa were recorded. L. fortunei and Nematoda were the central and dominant groups, with a prodigious abundance of over 80%. The prevalence of L. fortunei, rather than the environmental variables, regulated the dynamics of the associated invertebrate fauna. The golden mussel alters both the structure and function of benthic native communities on hard substrates, allows a higher surface available for colonization and refuge, and provides food source to deposit-feeding organisms in the form of organic or residual material. The mussel also increases the abundance and diversity of taxa on hard substrata - such as Oligochaeta, Hirudinea, Tardigrada, Chironomidae, Copepoda, Tanaidacea, and Hydrachnidia. Similarities and nonparametric multidimensional-scaling analyses indicated that the benthic composition had a seasonal variation. L. fortunei has an environmental impact, an ability to invade new freshwater ambiences worldwide and ecological characteristic comparable to those of Dreissena polymorpha Pallas (the zebra mussel of North America and Europe.
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Cánepa, Paula Analía
2013-01-01
El proyecto de intervención académica que aquí se desarrolla, consiste en implementar el examen clínico objetivo estructurado para la evaluación de habilidades y competencias clínicas (en adelante OSCE), en el curso de Semiología de la carrera de Ciencias Veterinarias de la Universidad Nacional de la Plata. Entendiendo por competencia, a la capacidad de poner en práctica destrezas, aptitudes y conocimientos necesarios para la construcción de la mirada clínica del futuro profesional. Dichas co...
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Heating tokamaks via the ion-cyclotron and ion-ion hybrid resonances
International Nuclear Information System (INIS)
Perkins, F.W.
1977-04-01
For the ion-ion hybrid resonance it is shown that: (1) the energy absorption occurs via a sequence of mode conversions; (2) a poloidal field component normal to the ion-ion hybrid mode conversion surface strongly influences the mode conversion process so that roughly equal electron and ion heating occurs in the present proton-deuterium experiments, while solely electron heating is predicted to prevail in deuterium-tritium reactors; (3) the ion-ion hybrid resonance suppresses toroidal eigenmodes; and (4) wave absorption in minority fundamental ion-cyclotron heating experiments will be dominated by ion-ion hybrid mode conversion absorption for minority concentrations exceeding roughly 1 percent. For the ion-cyclotron resonance, it is shown that: (1) ion-cyclotron mode conversion leads to surface electron heating; and (2) ion-cyclotron mode conversion absorption dominates fundamental ion-cyclotron absorption thereby preventing efficient ion heating
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Pántano, Vanesa C.; Penalba, Olga C.
2017-12-01
Projected changes were estimated considering the main variables which take part in soil-atmosphere interaction. The analysis was focused on the potential impact of these changes on soil hydric condition under extreme precipitation and evapotranspiration, using the combination of Global Climate Models (GCMs) and observational data. The region of study is the southern La Plata Basin that covers part of Argentine territory, where rainfed agriculture production is one of the most important economic activities. Monthly precipitation and maximum and minimum temperatures were used from high quality-controlled observed data from 46 meteorological stations and the ensemble of seven CMIP5 GCMs in two periods: 1970-2005 and 2065-2100. Projected changes in monthly effective temperature and precipitation were analysed. These changes were combined with observed series for each probabilistic interval. The result was used as input variables for the water balance model in order to obtain consequent soil hydric condition (deficit or excess). Effective temperature and precipitation are expected to increase according to the projections of GCMs, with few exceptions. The analysis revealed increase (decrease) in the prevalence of evapotranspiration over precipitation, during spring (winter). Projections for autumn months show precipitation higher than potential evapotranspiration more frequently. Under dry extremes, the analysis revealed higher projected deficit conditions, impacting on crop development. On the other hand, under wet extremes, excess would reach higher values only in particular months. During December, projected increase in temperatures reduces the impact of extreme high precipitation but favours deficit conditions, affecting flower-fructification stage of summer crops.
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Directory of Open Access Journals (Sweden)
Gonzalo Julián Yurkievich
2013-12-01
Full Text Available La actividad pesquera argentina experimentó durante las décadas de 1980 y de 1990 profundas transformaciones estructurales que impactaron con fuerza en las formaciones sociales relacionadas en forma directa e indirecta con la industria. La trasformación involucró, además, un deterioro del espacio y del medio ambiente de la zona portuaria de la ciudad de Mar del Plata. El presente análisis apunta a identificar este deterioro, a explicar los motivos por los cuales se generó el mismo, y a establecer los órdenes de competencia y responsabilidad en el tema. Partimos de la idea de que durante el régimen de acumulación capitalista denominado recurrentemente como neoliberal, existió una retracción del Estado y una reducción de la inversión pública en infraestructuras así como una creciente externalización del costo ambiental por parte de los privados, generándose, así, un creciente deterioro del medio ambiente urbano en las ciudades argentinas.
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de León Meza, C. René
2011-08-01
Full Text Available This article shows the economic significance of the group of mines that belonged to the jurisdiction of the «Caja de Guadalajara». The novelty lies in that local historiography had erroneously labeled these mining camps as being small. Recent studies show that they were not so small after all. These groups of mines were the focal point of the economy of a vast region and triggered the development of agriculture, livestock and trade activities. This article reveals the nexus between the fluctuations in silver production and events in Europe.
Este artículo da a conocer la importancia económica que tuvo un conjunto de reales de minas que perteneció a la jurisdicción de la caja de Guadalajara. Es novedoso porque por primera vez son estudiados aquéllos que la historiografía local ha considerado erróneamente como «pequeños reales de minas». Estas explotaciones fueron el eje articulador de la economía en una vasta región que impulsó el desarrollo de la ganadería, agricultura y comercio. Vincula las fluctuaciones en la producción de plata con sucesos ocurridos en Europa. -
Halls, Henry C.; Campal, Nestor; Davis, Don W.; Bossi, Jorge
2001-09-01
A U-Pb age on baddeleyite of 1790±5 Ma has been obtained from a single dyke of the Uruguayan tholeiitic dyke swarm from the Rio de la Plata craton. Palaeomagnetic results from this and 10 other dykes yield two components, one (A) has the following paleomagnetic parameters: declination=12°, inclination=-16°, α95=7°, latitude of paleopole=61°, longitude=-31°, dp=4°, dm=7°, paleolatitude=-8°, whereas another (B), about 20° steeper, has a direction closer to the present Earth's field direction in Uruguay. Neither magnetisation is considered primary, although the A component may represent a composite between B and a primary component. A field test for the primary nature of the remanences was inconclusive, and no primary pole positions of similar age from other South American cratons are available for comparison. The magnetic results demonstrate that darker-coloured andesite dykes that are sought for facing and monument stone (as 'black granite') can be easily differentiated from more andesi-basaltic, lighter coloured, less valuable dykes of the same swarm, using aeromagnetic data. The results suggest that a high resolution airborne magnetic survey could constitute an important exploration tool for the Uruguayan 'black granite' industry.
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Acosta, A.A., Buc, N., Davrieux, M.N.
2015-01-01
Full Text Available En este trabajo se analizan los conjuntos ornamentales generados por las poblaciones humanas prehispánicas que ocuparon el extremo meridional de la cuenca del Plata. Se describen las piezas recuperadas en diversos sitios arqueológicos teniendo en cuenta las materias primas empleadas, sus mecanismos de obtención y otros aspectos relacionados con la manufactura. Posteriormente se evalúa y discute su potencial uso como medios de transmisión de información. Para ello se consideran diferentes factores vinculados con los sistemas de intercambio y la extensión de las redes sociales en el marco del crecimiento demográfico y del grado de complejidad social que alcanzaron dichas poblaciones durante la fase final del Holoceno tardío.
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Rodolfo Elías
2006-12-01
Full Text Available Continuous and short-term disturbances are produced on intertidal Brachidontes rodriguezii mussel beds by the sewage outfall of Mar del Plata, SW Atlantic. The effects on the associated polychaetes living on and between mussels were investigated, in both the spatial and short-term temporal scales. Multivariate methods show that the polychaete fauna was influenced by tidal level, total amount of sediment accumulated between mussels, distance from the sewage outfall, organic carbon of interstitial sediments, and sewage volume before and after the summer season. Environmental variables in the water column fitted with a spatial and temporal organic gradient. Capitella ‘capitata’ sp. showed typical opportunistic behaviour in relation to organic enrichment, as did Neanthes succinea, both being numerically dominant near the sewage discharge. Cirratulus sp., Caulleriella alata, and Boccardia polybranchia were common at intermediate distances from the outfall. Syllis prolixa, S. gracilis, and Protoariciella uncinata reached their highest abundance at intermediate stations and were characteristic of the control site. Close to the outfall mussel density and dominance is low, and opportunist polychaetes successfully colonize organically enriched interstitial sediments. At intermediate distances from the outfall sediments retained by mussels reach their maximum values, and density of polychaetes is also high. The control station is characterized by monolayered mussel beds and very low diversity of polychaetes. Opportunistic polychaetes increase in response to short-term increases of sewage discharge during the summer season (November-March.
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Avances en los métodos de recuperación de oro y plata de minerales refractarios
Directory of Open Access Journals (Sweden)
Parga, J. R.
1996-08-01
Full Text Available Recent research work in hydrometallurgical processes for precious metals recovery from refractory ores is analyzed. Advantages and applications are discussed. Likewise, two methods, one stage direct pressure oxidation/cyanidation and pyrometallurgical recovery, are also described. In the first one, gold and silver oxidation and recovery can be carried out in the same reactor simultaneously. A higher than 96 % recovery in less than 90 min can be achieved. As for the pyrometallurgical recovery method, lead paste from automotive discharged batteries is use and no sulfur dioxide is generated. A precious metals recovery higher than 96 % is reached.
En este artículo se analizan algunos de los avances introducidos en los procedimientos hidrometalúrgicos para la recuperación de los metales preciosos contenidos en minerales refractarios y se describen sus ventajas y aplicaciones específicas. Asimismo, se muestran dos procedimientos, la cianuración oxidante a presión en una etapa y la recuperación pirometalúrgica con plomo de metales preciosos. En el proceso de cianuración oxidante a presión, la oxidación y disolución del oro y de la plata se realizan simultáneamente en el mismo reactor, con recuperaciones de ambos superiores al 96 % en 90 min. Con respecto al método de recuperación pirometalúrgica, se emplea pasta de plomo de baterías de automóviles desechadas, sin que se genere dióxido de azufre, obteniéndose también elevados valores de recuperación de los metales preciosos (> 96 %. -
African Journals Online (AJOL)
2011-10-25
Oct 25, 2011 ... Ingeniería, Universidad Nacional de Mar del Plata, J.B. Justo 4302,. 7600 Mar del Plata, ..... de Mar del Plata, the Consejo Nacional de Investigaciones. Científicas y Técnicas (CONICET) 2010-2011 PIP 00082, the Agencia ...
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Directory of Open Access Journals (Sweden)
Julio A. Hurrell
2016-01-01
Full Text Available Este trabajo incluye resultados parciales de una línea de investigación en Etnobotánica urbana, que estudia los conocimientos locales sobre las plantas, sus partes y productos derivados en la conurbación Buenos Aires-La Plata. Se incluyen productos de plantas medicinales de reciente ingreso en el área de estudio a través de inmigrantes oriundos de Paraguay. Los productos corresponden a 10 especies: Achyrocline alata(“jateí-ka’á”, Baccharis gaudichaudiana (“jaguareté-ka’á”, Cuphea lysimachioides(“ysypó-peré”, Euphorbia serpens(“tupasý-kambý”, Genipa americana(“ñandypá”, Helietta apiculata(“yvyra ovy”, Lycopodiella cernnua(“itápotý”, Rhynchosia balansae(“urusú-he’ě”, Stevia rebaudiana(“ka’á-he’ě” y Victoria cruziana(“jacaré-yrupé”. Para cada caso se indican sus productos, muestras de referencia, usos asignados, actividad biológica y efectos estudiados. La presencia de los productos de estas especies en el área metropolitana indica un aumento de la diversidad biocultural local, tanto de plantas y productos como de sus conocimientos asociados.
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Directory of Open Access Journals (Sweden)
D. Gomez
2005-12-01
Full Text Available Entre el 15 de octubre y el 8 de noviembre de 2003 ocurrió un brote de gastroenteritis en un Jardín Maternal de un Hospital de la ciudad de Mar del Plata. Catorce de un total de 80 niños (17,5%, edad promedio 23,6 ± 13,9 meses, presentaron diarrea, y un caso evolucionó a síndrome urémico hemolítico. La madre de uno de los afectados presentó diarrea simultáneamente. No se pudo establecer el origen del brote, pero probablemente la transmisión haya sido fundamentalmente persona a persona. Las prácticas habituales en el lactario del jardín maternal, y las condiciones inadecuadas de infraestructura y hábitos de higiene de la cocina del Hospital fueron señalados como factores de riesgo. En un caso se detectó Escherichia coli productor de toxina Shiga (STEC O103:H2, y STEC O26:H11 en otro. En el niño infectado por STEC O26:H11, la excreción se extendió por un período de 37 días. La no detección de STEC en aquellos casos en los cuales el intervalo entre el inicio de los síntomas y la toma de muestra fue mayor a 6 días, enfatiza la necesidad de la recolección temprana de especímenes. Las principales conclusiones de este estudio fueron la necesidad de establecer normas óptimas de higiene, informar rápidamente la ocurrencia de casos de gastroenteritis y confirmar la negativización de la excreción del patógeno.From October 15 to November 8, 2003, a gastrointestinal outbreak occurred at a day care center in a Hospital in Mar del Plata City. Fourteen out of 80 (17.5% children, mean age 23.6 ± 13.9 months, and the mother of one of them had diarrhea. One case developed hemolytic uremic syndrome. No conclusive evidence of the origin of the outbreak was found, but the epidemic curve suggested person-to-person spread. The usual practices at the place where infant milk formula was prepared at the day care center, together with the inadequate infrastructure conditions and hygiene practices at the kitchen of the hospital, were
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Calculation of ion storage in electron beams with account of ion-ion interactions
International Nuclear Information System (INIS)
Perel'shtejn, Eh.A.; Shirkov, G.D.
1979-01-01
Ion storage in relativistic electron beams was calculated taking account of ion-ion charge exchange and ionization. The calculations were made for nitrogen ion storage from residual gas during the compression of electron rings in the adhezator of the JINR heavy ion accelerator. The calculations were made for rings of various parameters and for various pressures of the residual gas. The results are compared with analogous calculations made without account of ion-ion processes. It is shown that at heavy loading of a ring by ions ion-ion collisions play a significant part, and they should be taken into account while calculating ion storage
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International Nuclear Information System (INIS)
Preciozzi, F.; Peel, E.; Sanchez, L.; Basei, M.; Ledesma, J.; Muzio, R.
2005-01-01
This research was framed in an interdisciplinary project, whose main objective was to make an approach to the geological, tectonic and geochronological evolution of Dom Feliciano Belt and adjacent land partners, especially the Río de la Plata Craton and Land Punta del Este. As was proposed in the project, special attention to geochronological studies from geological transects lent controlled. This yielded the expected level major step forward, not only with regard to the age of different units, but what makes the establishment of an adequate stratigraphy of them. Similarly, geochemical, petrographic and geochronological studies allowed essentially make geotectonic and geologic correlations with the southern portion of Brazil and the western portion of the land I africanos.lo expand involving more project goals in si.En effect began to manifest as a need to know the evolution of equivalent units both in the southern portion of Brazil and Africa Occidental.Estos fundamentalmnete work with West Africa were made with contributions from CONICYT Project 6009 under Projects Geological Correlation 438, 450 and 478 .this pertimitio exchange ideas with leading scientists worldwide many of whom ended up collaborating with it
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Ion-Ion Plasmas Produced by Electron Beams
Fernsler, R. F.; Leonhardt, D.; Walton, S. G.; Meger, R. A.
2001-10-01
The ability of plasmas to etch deep, small-scale features in materials is limited by localized charging of the features. The features charge because of the difference in electron and ion anisotropy, and thus one solution now being explored is to use ion-ion plasmas in place of electron-ion plasmas. Ion-ion plasmas are effectively electron-free and consist mainly of positive and negative ions. Since the two ion species behave similarly, localized charging is largely eliminated. However, the only way to produce ion-ion plasmas at low gas pressure is to convert electrons into negative ions through two-body attachment to neutrals. While the electron attachment rate is large at low electron temperatures (Te < 1 eV) in many of the halogen gases used for processing, these temperatures occur in most reactors only during the afterglow when the heating fields are turned off and the plasma is decaying. By contrast, Te is low nearly all the time in plasmas produced by electron beams, and therefore electron beams can potentially produce ion-ion plasmas continuously. The theory of ion-ion plasmas formed by pulsed electron beams is examined in this talk and compared with experimental results presented elsewhere [1]. Some general limitations of ion-ion plasmas, including relatively low flux levels, are discussed as well. [1] See the presentation by D. Leonhardt et al. at this conference.
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Directory of Open Access Journals (Sweden)
Juan A. Waessle
2003-06-01
Full Text Available Seven species of the family Sciaenidae have been reported inhabiting bottom waters of the Río de la Plata estuary. Of these juvenile stripped weakfish (Cynoscion guatucupa, king weakfish (Macrodon ancylodon, whitemouth croaker (Micropogonias furnieri and banded ground drum (Paralonchurus brasiliensis are by far the most abundant. These species are also important prey of several top-predator species among large fishes, seabirds and mammals. In this study we provide new information regarding otolith morphology and body size relationships of juvenile sciaenid fish. The sagittae morphology of juvenile sciaenids showed strong changes in the course of their development (e.g. in overall shape and development of concrescences on the outer surface. Analysing the morphometric relationships, we concluded that otolith length and otolith mass are good indicators of fish standard length and fish weight in all species. If otolith length or mass is used to estimate fish length, the regression explained more than 97% of the variation in all species. All equations relating fish standard length and fish weight for juvenile stages of the species studied explained a very large proportion of the variance in the data. These data will help researchers studying food habits of top predators to determine size and weight of usually juvenile fish-prey from length, broad and/or weight of recovered otoliths.
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International Nuclear Information System (INIS)
Cantera Kintz, Jaime Ricardo
2005-01-01
The environmental management of Tran-boundary water bodies presents several limitations, ranging from the complex geographical and environmental contexts to differences in jurisdiction and governance, and also involving the interdisciplinary topics included in the integrated environmental management. Any program of environmental planning mainly needs of scientific research made in a close coordination and cooperation, since underestimated aspects cause management weakness. This paper describes the contexts in which the Argentinean-Uruguayan Binational Project Environmental Protection of the Rio de la Plata and its Maritime Front (RPFM) is developed, the main tools to build the scientific knowledge, and the strategies followed to implement a cooperative framework with the participation of environmental management and research institutions of both countries in the pursue of Project objectives
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Lavayén, Silvina; Zotta, Claudia; Cepeda, Marcela; Lara, Claudia; Rearte, Analia; Regueira, Mabel
2017-01-01
. To classify the study population in the Argentinian National Health Surveillance System framework, determine the proportion of infection by Bordetella pertussis and Bordetella parapertussis, and identify factors associated with the cases of suspected whooping cough attended to in the city of Mar del Plata and its outskirts during the period 2011- 2015. An observational and descriptive study was carried out. Clinical cases with suspicion of whooping cough were diagnosed by laboratory. The laboratory studies consisted of culture, PCR, and serology using the ELISA technique. A total of 572 cases were evaluated. The female sex was the most frequent (51.9%). The most frequent age range was 2 to 17 moths (51.1%; 290/568), which was also the group with the most confirmed cases. Only 47.8% (155/324) of the population studied had complete vaccination for their age. Whooping cough due to B. pertussis was confirmed in 15.5% (89/572) of cases and one case with B. parapertussis. Those cases that had contact with a coughing relative were significantly associated with the confirmation of Bordetella spp. by the laboratory (odds ratio: 3.3; 95% confidence interval: 1.9-5.4). The results show the need to suspect whooping cough and diagnose it early in children, adolescents, and adults in order to better control the disease. Likewise, continuing prevention and containment measures are fundamental in decreasing the circulation of the causal agent.
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Imagen y palabra en la evangelización y catequesis de la Ruta de La Plata. Potosi–Arica
Directory of Open Access Journals (Sweden)
Guzmán, Fernando
2014-12-01
Full Text Available The following article intends to recreate, by means of studying a number of wall paintings in the churches located in the “Ruta de la Plata” (Silver route trade between Potosi mining village and Arica's port, analyzing the catechisms of the Third Council of Lima (1584, the way in which the Christianization and catechesis process took place in these locations. Based in the trilogy listened word, memorized formula, and contemplated-remembered image of the religious paintings, the research purpose is focused on detecting how that particular articulation modified or determined the remembrance that the observers made of them. In addition, it will deepen in the way the paintings were observed, and in the images that were created in memory, figuring how they gave life to a particular Christian experience for the inhabitants of this territory.El presente trabajo se propone reconstruir, a través del estudio de las pinturas murales en las iglesias ubicadas en la Ruta de la Plata y del análisis de los catecismos del Tercer Concilio limense, la forma como podría haber operado el método de evangelización y catequesis fundado en la trilogía: palabra escuchada, fórmula memorizada, imagen contemplada y recordada. Buscando proponer de qué manera esa articulación modificaba o determinaba la observación o la recordación de las pinturas religiosas o, en la dirección contraria, de qué forma las pinturas observadas o la imagen de ellas en la memoria daban forma a la vida cristiana de quienes habitaban este territorio.
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International Nuclear Information System (INIS)
Preciozzi, F.; Sanchez Bettucci, L.; Oyhantcabal, P.; Pecoits, E.; Aubet, N.; Peel, E.; Basei, M.
2003-01-01
Brazilian Shield (Rio Grande do Sul) where Paleoproterozoic os land, located in the region Western, are covered by Paleozoic sediments of the Paraná Basin. The Neoproterozoic domains develop east of the Precambrian shield of Uruguay. The Exceptions to this comparative correlation are represented by the Campanero Unit and Field Suspect Punta del Este, only identified in Uruguayan territory. The Piedra Alta (Río de la Plata Craton, ss.) Is composed of a complex gneissic-migmatítico plant, essentially composed of porphyritic foliated granitoids interspersed with different types of mafic rocks Paleoproterozoicas Migmatites and, at least in the southern portion, where four metamorphic belts of different degree and extent are interleaved (Montevideo, San Jose, Cerros de San Juan and Arroyo Grande). Granites, granodiorites, and bodies mafic, of different composition, age and location environment are intruding the whole ground. The last magmatic activity is represented by a swarm of dykes aged mafic ca. 1750 - 1790 Ma (Bossi and Pitched, 1991, Halls et al., 2001) and meta tuffs acid intercalated in the Belt of Los Cerros de San Juan whose ages by the method U / Pb located in the vicinity of 1753 ± 5 Ma (Preciozzi et al, in prep.). The Piedra Alta Terrane no evidence of being affected by events tectonotérmicos Neoproterozoic and is separated from the Block Valentines by the shear zone Sarandi del Yi (Preciozzi et al., 1979). From geochronological studies U / Pb, Rb / Sr, K / Ar and Sm / Nd recent, carried out on the rocks Intrusive and Piedra Alta Land gneisses, it has been possible to observe a set of events that They affected the Land
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Directory of Open Access Journals (Sweden)
Giuseppe Gatti
2012-12-01
Full Text Available Dentro de la narrativa hispanoamericana del siglo XX, el presente estudio analiza el papel desempeñado por los procesos de rememoración en el espacio literario uruguayo contemporáneo. El trabajo se propone concentrar la atención en las dinámicas de recuperación del tiempo pasado en la obra del montevideano Hugo Burel (1951, y en particular en su novela Tijeras de Plata (2003. La primera parte de nuestro estudio se centrará en el impacto sobre una novela de ambientación típicamente montevideana que plasma a nivel simbólico los cambios geo-sociales que han caracterizado el espacio uruguayo a partir de la segunda mitad del siglo XX (descentralización poblacional urbana; paulatino quiebre en el tejido social, cultural y económico de barrios enteros; desaparición de vestigios materiales e inmateriales del pasado arcádico. Se pondrán en relación estos fenómenos con las formas narrativas utilizadas (relatos enmarcados, lo cual nos ofrecerá la oportunidad de reflexionar sobre otro tipo de fragmentación, de naturaleza extra-literaria. El objetivo consistirá en identificar una relación de causa/efecto entre la literatura y un determinado espacio social: en el caso de Uruguay, nos referimos a esa sensación de «fractura» con el pasado que experimentó, a todo nivel, la sociedad uruguaya. En la segunda parte, se evidenciará cómo Tijeras de Plata es una novela de reivindicación de un pasado desaparecido, que construye gran parte de su esencia como «narración de la memoria» sobre la evidencia –y no la condena– del proceso de pauperización experimentado por amplias zonas urbanas de la ciudad. Se centrará la atención en la manera en que la novela bureliana recupera el espacio del recuerdo, no en términos melancólicos ni de exaltación nostálgica de un pasado nunca olvidado. Se intenta, por el contrario, demostrar cómo la doble operación de rescate (por un lado, de las memorias individuales relacionadas con el barrio; por
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Majority ion heating near the ion-ion hybrid layer in tokamaks
International Nuclear Information System (INIS)
Phillips, C.K.; Hosea, J.C.; Ignat, D.; Majeski, R.; Rogers, J.H.; Schilling, G.; Wilson, J.R.
1995-08-01
Efficient direct majority ion heating in a deuterium-tritium (D-T) reactor-grade plasma via absorption of fast magnetosonic waves in the ion cyclotron range of frequencies (ICRF) is discussed. Majority ion heating results from resonance overlap between the cyclotron layers and the D-T ion-ion hybrid layer in hot, dense plasmas for fast waves launched with high parallel wavenumbers. Analytic and numerical models are used to explore the regime in ITER plasmas
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An RF ion source based primary ion gun for secondary ion mass spectroscopy
International Nuclear Information System (INIS)
Menon, Ranjini; Nabhiraj, P.Y.; Bhandari, R.K.
2011-01-01
In this article we present the design, development and characterization of an RF plasma based ion gun as a primary ion gun for SIMS application. RF ion sources, in particular Inductively Coupled Plasma (ICP) ion sources are superior compared to LMIS and duoplasmtron ion sources since they are filamentless, can produce ions of gaseous elements. At the same time, ICP ion sources offer high angular current density which is an important factor in producing high current in small spot size on the target. These high current microprobes improve the signal to noise ratio by three orders as compared to low current ion sources such as LMIS. In addition, the high current microprobes have higher surface and depth profiling speeds. In this article we describe a simple ion source in its very basic form, two lens optical column and characteristics of microprobe
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Journal of Chemical Sciences | Indian Academy of Sciences
Indian Academy of Sciences (India)
Author Affiliations. Romina A Frenzel1 Gustavo P Romanelli1 Mirta N Blanco1 Luis R Piz1. Centro de Investigación y Desarrollo en Ciencias Aplicadas ``Dr. Jorge J. Ronco” (CINDECA), CCT-LaPlata-CONICET, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 N° 257 (B1900AJK) La Plata, Argentina ...
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Ion mixing and numerical simulation of different ions produced in the ECR ion source
International Nuclear Information System (INIS)
Shirkov, G.D.
1996-01-01
This paper is to continue theoretical investigations and numerical simulations in the physics of ECR ion sources within the CERN program on heavy ion acceleration. The gas (ion) mixing effect in ECR sources is considered here. It is shown that the addition of light ions to the ECR plasma has three different mechanisms to improve highly charged ion production: the increase of confinement time and charge state of highly ions as the result of ion cooling; the concentration of highly charged ions in the central region of the source with high energy and density of electrons; the increase of electron production rate and density of plasma. The numerical simulations of lead ion production in the mixture with different light ions and different heavy and intermediate ions in the mixture with oxygen, are carried out to predict the principal ECR source possibilities for LHC applications. 18 refs., 23 refs
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Recoil ion spectroscopy with heavy ions
International Nuclear Information System (INIS)
Beyer, H.F.; Mann, R.
1984-01-01
This chapter examines the production of very high charge state ions in single ion-atom collisions. Topics considered include some aspects of highly ionized atoms, experimental approaches, the production of highly charged target ions (monoatomic targets, recoil energy distribution, molecular fragmentation, outer-shell rearrangement, lifetime measurements, a comparison of projectile-, target-, and plasma-ion stripping), and secondary collision experiments (selective electron capture, potential applications). The heavy-ion beams for the described experiments were provided by accelerators such as tandem Van de Graaff facility and the UNILAC
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Directory of Open Access Journals (Sweden)
Carolina Soledad Vagge
Full Text Available El crecimiento urbano introduce permanente presión a las áreas metropolitanas. En países periféricos la demanda de energía crece a mayor velocidad que el crecimiento poblacional y la oferta, creando crisis y escasez. El objetivo principal de este trabajo es prever el impacto que tendrá la Ley 13059 de Eficiencia Energética en relación a la nueva Ordenanza de Usos del Suelo de la ciudad de La Plata y la Norma de Etiquetado de Edificios (IRAM 11900. Esta norma establece una metodología simplificada para el cálculo del nivel de eficiencia energética de las envolventes de los edificios susceptibles de ser calefaccionados. Todavía, es evidente que existe una importante falta de adecuación entre los objetivos teóricos formulados para el desarrollo de la ciudad y las conflictivas estrategias técnicas propuestas para satisfacerlos. En cuanto a la aplicación de la ley de eficiencia energética al modelo de edificio de construcción usual en La Plata, no verifica sus valores de transmitancia térmica K. Tampoco verifica el riesgo de condensación ni el coeficiente global de pérdidas G. Del mismo modo, cuando se aplica el protocolo de etiquetado de eficiencia energética que plantea la norma IRAM 11900, el edifico clasifica como H. Se puede ver que el impacto de ahorro potencial en la demanda de energía anual para calefacción, si se comienza a implementar la Ley de Eficiencia Energética sería de un 46%.
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Surface negative ion production in ion sources
International Nuclear Information System (INIS)
Belchenko, Y.
1993-01-01
Negative ion sources and the mechanisms for negative ion production are reviewed. Several classes of sources with surface origin of negative ions are examined in detail: surface-plasma sources where ion production occurs on the electrode in contact with the plasma, and ''pure surface'' sources where ion production occurs due to conversion or desorption processes. Negative ion production by backscattering, impact desorption, and electron- and photo-stimulated desorption are discussed. The experimental efficiencies of intense surface negative ion production realized on electrodes contacted with hydrogen-cesium or pure hydrogen gas-discharge plasma are compared. Recent modifications of surface-plasma sources developed for accelerator and fusion applications are reviewed in detail
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Directory of Open Access Journals (Sweden)
Sofía Romanelli
2013-03-01
Full Text Available Aquest article té tres objectius: proposar una metodologia per a la selecció dels sons de l’espanyol com a llengua segona i estrangera (ELSE per a ensenyar en un curs d’immersió, presentar una anàlisi contrastiva dels sons vocàlics i consonàntics de l’espanyol del Riu de la Plata (ERP i de l’anglès americà general (AAG, i elaborar un inventari dels sons de l’ERP que haurien de ser tractats en una classe d’ELSE.
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Directory of Open Access Journals (Sweden)
Fernando Manuel Graña
2012-12-01
Full Text Available El caso presentado muestra los elementos más relevantes de la intervención de la OIT en la Región Mar del Plata. Esta tiene por objeto la generación de trabajo decente y la mejora competitiva del entramado productivo local. Los principales logros son, la constitución de 5 mesas de concertación; la definición e implementación de sus acciones estratégicas; el fortalecimiento de instituciones empresariales, sindicales, científicas, tecnológicas, de formación técnica y universitaria. La creación de 3 centros de servicios tecnológicos (naval, indumentaria, TIC y de 2 asociaciones empresarias (Indumentaria y TIC, la instalación de más de 100 máquinas industriales en escuelas técnicas, la capacitación de más de 80 formadores y más de 1800 desocupados, la recalificación de más de 100 ocupados y la formación de más de 500 técnicos, profesionales y empresarios. ABSTRACT This case shows the most important elements in the OIT’s intervention in the Mar del Plata region. It has the goal to provide decent jobs generation and the competitive improvement of the local productive framework. Its main achievements are: the setting up of 5 discussion boards; the definition and running of strategic actions; the strengthening of entrepreneurial, labor union, scientific and technological institutions (naval, garment, TICs, and of 2 entrepreneurial associations (Garment and TICs; the installation of over a 100 industrial machines in vocational schools; the training of over 80 teachers and 1,800 jobless individuals; the requalification of more than 100 workers and training of over 500 technicians, professionals and entrepreneurs.
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International Nuclear Information System (INIS)
Salzborn, Erhard; Melchert, Frank
2000-01-01
Collisions between ions belong to the elementary processes occurring in all types of plasmas. In this article we give a short overview about collisions involving one-electron systems. For collisions involving multiply-charged ions we limit the discussion to one specific quasi-one-electron system. (author)
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Numerical simulation of ion temperature gradient driven modes in the presence of ion-ion collisions
International Nuclear Information System (INIS)
Xu, X.Q.
1990-08-01
Ion temperature gradient driven modes in the presence of ion-ion collisions in a toroidal geometry with trapped ions have been studied by using a 1 2/2 d linearized gyro-kinetic particle simulation code in the electrostatic limit. The purpose of the investigation is to try to understand the physics of flat density discharges, in order to test the marginal stability hypothesis. Results giving threshold conditions of L Ti /R 0 , an upper bound on k χ , and linear growth rates and mode frequencies over all wavelengths for the collisionless ion temperature gradient driven modes are obtained. The behavior of ion temperature gradient driven instabilities in the transition from slab to toroidal geometry, with trapped ions, is shown. A Monte Carlo scheme for the inclusion of ion-ion collisions, in which ions can undergo Coulomb collisional dynamical friction, velocity space diffusion and random walk of guiding centers, has been constructed. The effects of ion-ion collisions on the long wave length limit of the ion modes is discussed. 44 refs., 12 figs
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Cinco días de acceso a la realidad social
Directory of Open Access Journals (Sweden)
MIGUEL BELTRÁN
1985-01-01
Full Text Available La realidad social es muy diversa. Por tanto, las Ciencias Sociales no sólo deben emplear el modelo de las Ciencias Naturales, que se construyen sobre bases positivistas y cuantitativas, sino emplear otros instrumentos. Así, usa aproximaciones teóricas diversas como el método histórico, la metodología cualitativa, , el método comparativo y el crítico-racional. Se expone qué método es el apropiado en función del objeto de estudio y su dimensión social.
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Scanning ion microscopy with low energy lithium ions
International Nuclear Information System (INIS)
Twedt, Kevin A.; Chen, Lei; McClelland, Jabez J.
2014-01-01
Using an ion source based on photoionization of laser-cooled lithium atoms, we have developed a scanning ion microscope with probe sizes of a few tens of nanometers and beam energies from 500 eV to 5 keV. These beam energies are much lower than the typical operating energies of the helium ion microscope or gallium focused ion beam systems. We demonstrate how low energy can be advantageous in ion microscopy when detecting backscattered ions, due to a decreased interaction volume and the potential for surface sensitive composition analysis. As an example application that demonstrates these advantages, we non-destructively image the removal of a thin residual resist layer during plasma etching in a nano-imprint lithography process. - Highlights: • We use an ion source based on photoionization of laser-cooled lithium atoms. • The ion source makes possible a low energy (500 eV to 5 keV) scanning ion microscope. • Low energy is preferred for ion microscopy with backscattered ions. • We use the microscope to image a thin resist used in nano-imprint lithography
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Ion microtomography using ion time-of-flight
International Nuclear Information System (INIS)
Roberts, M.L.; Heikkinen, D.W.; Proctor, I.D.; Pontau, A.E.; Olona, G.T.; Felter, T.E.; Morse, D.H.; Hess, B.V.
1992-01-01
We have developed and are in the process of testing an ion time-of-flight (TOF) detector system for use in our ion microtomography measurements. Using TOF, ion energy is determined by measurement of the ion's flight time over a certain path length. For ion microtomography, the principle advantage of TOF analysis is that ion count rates of several hundred thousand counts per second can be achieved as compared to a limit of about ten thousand ions per second when using a solid-state silicon surface barrier detector and associated electronics. This greater than 10 fold increase in count rate correspondingly shortens sample analysis time or increases the amount of data that can be collected on a given sample. Details of the system and progress to date are described
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International Nuclear Information System (INIS)
Dearnaley, Geoffrey
1975-01-01
First, ion implantation in semiconductors is discussed: ion penetration, annealing of damage, gettering, ion implanted semiconductor devices, equipement requirements for ion implantation. The importance of channeling for ion implantation is studied. Then, some applications of ion implantation in metals are presented: study of the corrosion of metals and alloys; influence or ion implantation on the surface-friction and wear properties of metals; hyperfine interactions in implanted metals
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Gutierrez, Alejandra Concepción; Tornesello-Galván, Julieta; Manfrino, Romina Guadalupe; Hipperdinger, Marcela; Falvo, Marianel; D'Alessandro, Celeste; López Lastra, Claudia Cristina
The collection of fungal pathogens and symbionts of insects and other arthropods of the Centro de Estudios Parasitológicos y de Vectores, La Plata, Argentina, is unique because it preserves in vivo and in vitro cultures of fungal pathogens. This culture collection is open for research, teaching, consulting services, and strain deposit. It contains 421 strains belonging to 23 genera (16 Ascomycota, 4 Entomophthoromycotina, 2 Glomeromycota and 1 Oomycota), and the cultures are preserved by different methods such as cryopreservation in freezer at -20°C and -70°C, paper, distilled water and lyophilization. Fungi were isolated from insects, other arthropods, and soil (by using insect baits and selective media). Species were identified by morphological features and in a few strains by molecular taxonomy (PCR of rDNA). This collection is a reference center for species identification/certifications, research and teaching purposes, strain deposit, transference and consultancy services, and its overall goal is to preserve the fungal germplasm and ex situ diversity. Most of the strains are native of Argentina. The collection was originated in 1988 and is registered in the Latin American Federation for Culture Collections and in the World Federation of Culture Collections. Copyright © 2016 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.
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Directory of Open Access Journals (Sweden)
Manuela Graciela González
2015-06-01
Full Text Available A critical reflection on the experience at Courts of female victims of gender violence is the aim of this paper. Provincial, national and international laws are the framework for the analysis. The raw material are their reports ( assesed from the perspective of the newest writings on the issue which stress the differences between the official discourse of the Administration of Justice and the victims' "accounts". Three different questions have been asked to guide our research: Are gender violence and poverty , factors linked to the lack of an effective Access to Justice? Which are the new factors observed everywhere and those which are present only in Latin America?Are there any changes in the social stereotypes which clear and ease the womens' path towards the administration of justice? En este artículo reflexionamos críticamente sobre la situación de las mujeres en La Plata-Argentina que padecen violencia de género cuando acceden a la administración de justicia. Para ello tomamos como marco referencial la normativa provincial, nacional e internacional. Utilizamos como insumo los testimonios de las mujeres, analizados a la luz de la literatura actual, que polemiza sobre la compleja y a veces contradictoria relación entre el discurso "oficial" de la Administración de justicia y los "relatos" de las mujeres. Nos interrogamos sobre tres ejes de trabajo que han orientado nuestra producción: ¿Qué intersecciones visualizamos entre violencia de género y pobreza como factores que obstaculizan el acceso a la justicia?¿Qué factores nuevos aparecen en contextos globalizados, y cuales son específicos de América Latina?¿Se observan cambios en los estereotipos sociales que despejan el camino de las mujeres a la administración de justicia? DOWNLOAD THIS PAPER FROM SSRN: http://ssrn.com/abstract=2611592
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Ion Beam Extraction by Discrete Ion Focusing
DEFF Research Database (Denmark)
2010-01-01
An apparatus (900) and methods are disclosed for ion beam extraction. In an implementation, the apparatus includes a plasma source (or plasma) (802) and an ion extractor (804). The plasma source is adapted to generate ions and the ion extractor is immersed in the plasma source to extract a fracti...
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Baird, Zane; Wei, Pu; Cooks, R Graham
2015-02-07
A method is presented in which ions are generated and manipulated in the ambient environment using polymeric electrodes produced with a consumer-grade 3D printer. The ability to focus, separate, react, and detect ions in the ambient environment is demonstrated and the data agree well with simulated ion behaviour.
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Study of ion exchange equilibrium and determination of heat of ion exchange by ion chromatography
International Nuclear Information System (INIS)
Liu Kailu; Yang Wenying
1996-01-01
Ion chromatography using pellicularia ion exchange resins and dilute solution can be devoted to the study of ion exchange thermodynamics and kinetics. Ion exchange equilibrium equation was obtained, and examined by the experiments. Based on ion exchange equilibrium, the influence of eluent concentration and resin capacity on adjusted retention volumes was examined. The effect of temperature on adjusted retention volumes was investigated and heats of ion exchange of seven anions were determined by ion chromatography. The interaction between anions and skeleton structure of resins were observed
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Polyatomic ions from a high current ion implanter driven by a liquid metal ion source
Pilz, W.; Laufer, P.; Tajmar, M.; Böttger, R.; Bischoff, L.
2017-12-01
High current liquid metal ion sources are well known and found their first application as field emission electric propulsion thrusters in space technology. The aim of this work is the adaption of such kind of sources in broad ion beam technology. Surface patterning based on self-organized nano-structures on, e.g., semiconductor materials formed by heavy mono- or polyatomic ion irradiation from liquid metal (alloy) ion sources (LMAISs) is a very promising technique. LMAISs are nearly the only type of sources delivering polyatomic ions from about half of the periodic table elements. To overcome the lack of only very small treated areas by applying a focused ion beam equipped with such sources, the technology taken from space propulsion systems was transferred into a large single-end ion implanter. The main component is an ion beam injector based on high current LMAISs combined with suited ion optics allocating ion currents in the μA range in a nearly parallel beam of a few mm in diameter. Different types of LMAIS (needle, porous emitter, and capillary) are presented and characterized. The ion beam injector design is specified as well as the implementation of this module into a 200 kV high current ion implanter operating at the HZDR Ion Beam Center. Finally, the obtained results of large area surface modification of Ge using polyatomic Bi2+ ions at room temperature from a GaBi capillary LMAIS will be presented and discussed.
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Experimental Evaluation of a Negative Ion Source for a Heavy Ion Fusion Negative Ion Driver
International Nuclear Information System (INIS)
Grisham, L.R.; Hahto, S.K.; Hahto, S.T.; Kwan, J.W.; Leung, K.N.
2004-01-01
Negative halogen ions have recently been proposed as a possible alternative to positive ions for heavy ion fusion drivers because electron accumulation would not be a problem in the accelerator, and if desired, the beams could be photo-detached to neutrals. To test the ability to make suitable quality beams, an experiment was conducted at Lawrence Berkeley National Laboratory using chlorine in an RF-driven ion source. Without introducing any cesium (which is required to enhance negative ion production in hydrogen ion sources) a negative chlorine current density of 45 mA/cm 2 was obtained under the same conditions that gave 57 45 mA/cm 2 of positive chlorine, suggesting the presence of nearly as many negative ions as positive ions in the plasma near the extraction plane. The negative ion spectrum was 99.5% atomic chlorine ions, with only 0.5% molecular chlorine, and essentially no impurities. Although this experiment did not incorporate the type of electron suppression technology that i s used in negative hydrogen beam extraction, the ratio of co-extracted electrons to Cl - was as low as 7 to 1, many times lower than the ratio of their mobilities, suggesting that few electrons are present in the near-extractor plasma. This, along with the near-equivalence of the positive and negative ion currents, suggests that the plasma in this region was mostly an ion-ion plasma. The negative chlorine current density was relatively insensitive to pressure, and scaled linearly with RF power. If this linear scaling continues to hold at higher RF powers, it should permit current densities of 100 45 mA/cm 2 , sufficient for present heavy ion fusion injector concepts. The effective ion temperatures of the positive and negative ions appeared to be similar and relatively low for a plasma source
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Laser-cooled atomic ions as probes of molecular ions
Energy Technology Data Exchange (ETDEWEB)
Brown, Kenneth R.; Viteri, C. Ricardo; Clark, Craig R.; Goeders, James E.; Khanyile, Ncamiso B.; Vittorini, Grahame D. [Schools of Chemistry and Biochemistry, Computational Science and Engineering and Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States)
2015-01-22
Trapped laser-cooled atomic ions are a new tool for understanding cold molecular ions. The atomic ions not only sympathetically cool the molecular ions to millikelvin temperatures, but the bright atomic ion fluorescence can also serve as a detector of both molecular reactions and molecular spectra. We are working towards the detection of single molecular ion spectra by sympathetic heating spectroscopy. Sympathetic heating spectroscopy uses the coupled motion of two trapped ions to measure the spectra of one ion by observing changes in the fluorescence of the other ion. Sympathetic heating spectroscopy is a generalization of quantum logic spectroscopy, but does not require ions in the motional ground state or coherent control of the ion internal states. We have recently demonstrated this technique using two isotopes of Ca{sup +} [Phys. Rev. A, 81, 043428 (2010)]. Limits of the method and potential applications for molecular spectroscopy are discussed.
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Cómo hacer más efectiva la educación en salud en la atención primaria?
Directory of Open Access Journals (Sweden)
Wilfredo Guibert Reyes
Full Text Available Resumen: Se realiza una revisión bibliográfica sobre aspectos de la educación en salud con el objetivo de proveer estrategias y procedimientos metodológicos al médico y enfermera de la familia, que les permitan mejorar la efectividad de los mensajes de salud y emplear métodos de autorregulación para la adquisición de conductas protectoras y la modificación de hábitos saludables. Se analizan las nuevas concepciones de la comunicación y su utilización en los marcos del modelo sanitario de la competencia, se valoran las habilidades sociales que debe desarrollar y emplear el agente sanitario, estrategias que faciliten comprensión de los mensajes de salud, la utilización del consejo sanitario y se brinda la metodología para emplear el modelo proceso de adopción de precauciones. Se concluye que educación efectiva en salud no es informar, es necesario propiciar autocontrol con premisas económico-sociales para la salud pública
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Mesoproterozoic evolution of the Río de la Plata Craton in Uruguay: at the heart of Rodinia?
Gaucher, Claudio; Frei, Robert; Chemale, Farid; Frei, Dirk; Bossi, Jorge; Martínez, Gabriela; Chiglino, Leticia; Cernuschi, Federico
2011-04-01
Mesoproterozoic volcanosedimentary units and tectonic events occurring in the Río de la Plata Craton (RPC) are reviewed. A belt consisting of volcanosedimentary successions exhibiting greenschist-facies metamorphism is exposed in the eastern RPC (Nico Pérez Terrane) in Uruguay. The Parque UTE Group consists of basic volcanics and gabbros at the base (1,492 ± 4 Ma, U-Pb on zircon), carbonates in its middle part and interbedded carbonates, shales and acid volcanics (1,429 ± 21 Ma, U-Pb on zircon) at the top. The Mina Verdún Group is made up of rhyolites and acid pyroclastics at its base and top, and Conophyton-bearing limestones and massive dolostones in the middle. A U-Pb LA-ICP MS zircon age of 1,433 ± 6 Ma is reported here for lapilli-tuffs at the base of the Mina Verdún Group (Cerro de las Víboras Formation). This age shows that the Mina Verdún Group immediately postdates the Parque UTE Group, a fact supported by carbon isotope chemostratigraphy. Both units were deformed and metamorphosed between 1.25 and 1.20 Ga, as shown by K-Ar and Ar-Ar ages. This tectonic event affected most of the RPC and led to the accretion of the Nico Pérez Terrane to the remainder of the RPC along the Sarandí del Yí megashear. We report a U-Pb LA-ICP MS zircon age (upper intercept) of 3,096 ± 45 Ma for metatonalites of the La China Complex (Nico Pérez Terrane), which yield a lower intercept age of 1,252 Ma. A proto-Andean, Mesoproterozoic belt is envisaged to account for abundant Mesoproterozoic detrital zircon ages occurring in Ediacaran sandstones of the RPC. If the RPC is fringed at both sides by Mesoproterozoic, Grenville-aged belts it is likely that it occupied a rather central position in Rodinia. A possible location between Laurentia and the Kalahari Craton, and to the south of Amazonia, is suggested.
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A novel ion imager for secondary ion mass spectrometry
International Nuclear Information System (INIS)
Matsumoto, Kazuya; Miyata, Kenji; Nakamura, Tsutomu
1993-01-01
This paper describes a new area detector for secondary ion mass spectrometry (SIMS) ion microscope, and its performance. The operational principle is based on detecting the change in potential of a floating photodiode caused by the ion-induced secondary-electron emission and the incoming ion itself. The experiments demonstrated that 10 1 -10 5 aluminum ions per pixel can be detected with good linear response. Moreover, relative ion sensitivities from hydrogen to lead were constant within a factor of 2. The performance of this area detector provides the potential for detection of kiloelectronvolt ion images with current ion microscopy
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International Nuclear Information System (INIS)
Grisham, L.R.; Kwan, J.W.
2008-01-01
Some years ago it was suggested that halogen negative ions could offer a feasible alternative path to positive ions as a heavy ion fusion driver beam which would not suffer degradation due to electron accumulation in the accelerator and beam transport system, and which could be converted to a neutral beam by photodetachment near the chamber entrance if desired. Since then, experiments have demonstrated that negative halogen beams can be extracted and accelerated away from the gas plume near the source with a surviving current density close to what could be achieved with a positive ion of similar mass, and with comparable optical quality. In demonstrating the feasibility of halogen negative ions as heavy ion driver beams, ion - ion plasmas, an interesting and somewhat novel state of matter, were produced. These plasmas, produced near the extractor plane of the sources, appear, based upon many lines of experimental evidence, to consist of almost equal densities of positive and negative chlorine ions, with only a small component of free electrons. Serendipitously, the need to extract beams from this plasma for driver development provides a unique diagnostic tool to investigate the plasma, since each component - positive ions, negative ions, and electrons - can be extracted and measured separately. We discuss the relevance of these observations to understanding negative ion beam extraction from electronegative plasmas such as halogens, or the more familiar hydrogen of magnetic fusion ion sources. We suggest a concept which might improve negative hydrogen extraction by the addition of a halogen. The possibility and challenges of producing ion - ion plasmas with thin targets of halogens or, perhaps, salt, is briefly addressed.
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International Nuclear Information System (INIS)
Grisham, L.R.; Kwan, J.W.
2008-01-01
Some years ago it was suggested that halogen negative ions (1)could offer a feasible alternative path to positive ions as a heavy ion fusion driver beam which would not suffer degradation due to electron accumulation in the accelerator and beam transport system, and which could be converted to a neutral beam by photodetachment near the chamber entrance if desired. Since then, experiments have demonstrated that negative halogen beams can be extracted and accelerated away from the gas plume near the source with a surviving current density close to what could be achieved with a positive ion of similar mass, and with comparable optical quality. In demonstrating the feasibility of halogen negative ions as heavy ion driver beams, ion-ion plasmas, an interesting and somewhat novel state of matter, were produced. These plasmas, produced near the extractor plane of the sources, appear, based upon many lines of experimental evidence, to consist of almost equal densities of positive and negative chlorine ions, with only a small component of free electrons. Serendipitously, the need to extract beams from this plasma for driver development provides a unique diagnostic tool to investigate the plasma, since each component--positive ions, negative ions, and electrons--can be extracted and measured separately. We discuss the relevance of these observations to understanding negative ion beam extraction from electronegative plasmas such as halogens, or the more familiar hydrogen of magnetic fusion ion sources. We suggest a concept which might improve negative hydrogen extraction by the addition of a halogen. The possibility and challenges of producing ion-ion plasmas with thin targets of halogens or, perhaps, salt, is briefly addressed
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Directory of Open Access Journals (Sweden)
Martina Daniela Camiolo
2016-01-01
Full Text Available RESUMEN Se analizó la estructura del hábitat, el crecimiento relativo, la heteroquelia, la estructura poblacional, la madurez morfométrica y la fecundidad de Pachycheles laevidactylus Ortmann, 1892, durante Abril, Mayo y Junio del 2005, en sustratos naturales de Mar del Plata, Argentina (38°02'S, 57°31'W. La cobertura algal, la exposición al oleaje y el tiempo de inmersión varió de manera significativa entre estratos y entre meses. La morfometría de las quelas no manifestó diferencias entre sexos. Las hembras mostraron el abdomen más grande que los machos. Si bien existió la heteroquelia, no se detectó lateralidad. Las tallas (ancho de caparazón estuvieron comprendidas entre 0.67 mm a 9.3 mm para los machos, y entre 1.07 mm a 10.65 mm, para las hembras. La densidad de organismos varió entre meses y entre los estratos. La estructura poblacional, para el periodo de estudio, se explicó en función de la estructura del hábitat. La madurez morfométrica de las hembras fue registrada a los 4.38 mm de ancho de caparazón. El número de huevos se correlacionó positivamente con la talla de las hembras ovígeras con un mínimo de 2 huevos y un máximo de 160, pero esa relación dependió del avance en el desarrollo de los embriones.
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Directory of Open Access Journals (Sweden)
María Laura Crego
2015-12-01
Full Text Available Este artículo tiene como objetivo abordar la articulación de tres dimensiones de la desigualdad social —segregación urbana, segregación educativa y segmentación del mercado de trabajo— que configuran las posiciones desiguales de los jóvenes estudiantes del Plan FinEs2 en el espacio social. Al mismo tiempo, nos proponemos esbozar algunas líneas de análisis para el abordaje de las repercusiones de dicha experiencia en las trayectorias de los jóvenes. Para ello, desde una perspectiva cualitativa, trabajamos con entrevistas en profundidad a jóvenes estudiantes y a docentes del Plan FinEs2 en el Gran La Plata durante el período 2013-2014. Como resultado pudimos observar que la segregación urbana presenta profundas cercanías con las desigualdades en el mercado de trabajo y en el sistema educativo. Estas dimensiones de la desigualdad se encadenan, se combinan y se potencian en un proceso en el que las desventajas se acumulan y dan como resultado signos de la desigualdad social y su reproducción. Sin embargo, dimos cuenta de cuatro movimientos que el recorrido de la experiencia habilita: posiciones frente a las situaciones de aprendizaje, reconocimiento de la posibilidad de complementar actividades laborales y de formación, cambios en las posiciones en sus dinámicas familiares y en espacios de trabajo y significaciones en torno al título secundario
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Design study of primary ion provider for relativistic heavy ion collider electron beam ion source.
Kondo, K; Kanesue, T; Tamura, J; Okamura, M
2010-02-01
Brookhaven National Laboratory has developed the new preinjector system, electron beam ion source (EBIS) for relativistic heavy ion collider (RHIC) and National Aeronautics and Space Administration Space Radiation Laboratory. Design of primary ion provider is an essential problem since it is required to supply beams with different ion species to multiple users simultaneously. The laser ion source with a defocused laser can provide a low charge state and low emittance ion beam, and is a candidate for the primary ion source for RHIC-EBIS. We show a suitable design with appropriate drift length and solenoid, which helps to keep sufficient total charge number with longer pulse length. The whole design of primary ion source, as well as optics arrangement, solid targets configuration and heating about target, is presented.
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Ion-Beam-Excited Electrostatic Ion Cyclotron Waves
DEFF Research Database (Denmark)
Michelsen, Poul; Pécseli, Hans; Juul Rasmussen, Jens
1976-01-01
Self-excited electrostatic ion cyclotron waves were observed in an ion-beam-plasma system produced in a DP-operated Q-machine. The frequency of the waves showed the theoretically predicted variation with the magnetic field.......Self-excited electrostatic ion cyclotron waves were observed in an ion-beam-plasma system produced in a DP-operated Q-machine. The frequency of the waves showed the theoretically predicted variation with the magnetic field....
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Fanini, L.; Zampicinini, G.; Tsigenopoulos, C. S.; Barboza, F. R.; Lozoya, J. P.; Gómez, J.; Celentano, E.; Lercari, D.; Marchetti, G. M.; Defeo, O.
2017-03-01
Life-history, substrate choice and Cytochrome Oxidase I (COI) sequences were analysed in populations of two peracaridans, the supralittoral talitrid Atlantorchestoidea brasiliensis and the intertidal cirolanid Excirolana armata. Three populations of each species, from beaches with similar grain size and located at different points along the natural gradient generated by the Rio de la Plata estuary were analysed. Abundance of E. armata increased with distance from the estuary, while the opposite trend was observed for A. brasiliensis. The proportion of females decreased towards high salinities for both species, significantly for E. armata. A test on substrate salinity preference revealed the absence of patterns due to active choice in E. armata. By contrast, A. brasiliensis showed no preference for the population closer to the estuary, while individuals from the other two sites significantly preferred high salinity substrates. Mitochondrial COI sequences were obtained from A. brasiliensis specimens tested for behaviour. Sequence analysis showed the population from the intermediate site to differ significantly from the other two. No significant genetic differentiation was instead found between populations from the two most distant sites, nor between individuals that expressed different salinity preference. Results showed that diverse sets of traits at the population level enable sandy beach species to cope with local environmental changes: life-history and behavioural traits appear to change in response to different ecological conditions, and, in the case of A brasiliensis, independently of the population structure inferred from COI sequence variation. Information from multiple traits allowed detection of population profiles, highlighting the relevance of multidisciplinary information and the concurrent analysis of field data and laboratory experiments, to detect responses of resident biota to environmental changes.
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Ion mobilities and ion-atom interaction potentials
International Nuclear Information System (INIS)
Gatland, I.R.
1982-01-01
The techniques for measuring the mobilities of ions in gases, relating interaction potentials to mobilities, and determining potentials from experimental mobilities are reviewed. Applications are presented for positive alkali ions and negative halogen ions in inert gases. (Auth.)
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Directory of Open Access Journals (Sweden)
Viviana Kluger
2014-06-01
Full Text Available El objeto de este trabajo es analizar el rol femenino en el litigio familiar, a efectos de determinar la presencia de las mujeres a la hora de reclamar el cumplimiento de los deberes y derechos conyugales y paterno filiales en los pleitos entablados en el Virreinato del Río de la Plata. Se trata de medir los ajustes y desajustes, el conformismo y la contradicción entre el modelo propuesto desde la ley y la doctrina, y de contrastar esos esquemas con la praxis judicial. Se presenta primero un análisis del marco legal, para pasar luego al estudio de la asignación de roles familiares, expresada a través de la doctrina canónica y jurídica española de los siglos XVI a XIX, así como de la literatura de la época. Se tratan también el poder de corrección y el deber de subordinación, el rol femenino a través de los litigios familiares, en la defensa del honor y en las alianzas matrimoniales, y se consideran las variaciones según el tiempo, el espacio y la clase social. Por último se exponen unas consideraciones finales acerca de la eventual brecha entre el modelo y la realidad.
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Low-altitude ion heating with downflowing and upflowing ions
Shen, Y.; Knudsen, D. J.; Burchill, J. K.; Howarth, A. D.; Yau, A. W.; James, G.; Miles, D.; Cogger, L. L.; Perry, G. W.
2017-12-01
Mechanisms that energize ions at the initial stage of ion upflow are still not well understood. We statistically investigate ionospheric ion energization and field-aligned motion at very low altitudes (330-730 km) using simultaneous plasma, magnetic field, wave electric field and optical data from the e-POP satellite. The high-time-resolution (10 ms) dataset enables us to study the micro-structures of ion heating and field-aligned ion motion. The ion temperature and field-aligned bulk flow velocity are derived from 2-D ion distribution functions measured by the SEI instrument. From March 2015 to March 2016, we've found 17 orbits (in total 24 ion heating periods) with clear ion heating signatures passing across the dayside cleft or the nightside auroral regions. Most of these events have consistent ion heating and flow velocity characteristics observed from both the SEI and IRM instruments. The perpendicular ion temperature goes up to 4.5 eV within a 2 km-wide region in some cases, in which the Radio Receiver Instrument (RRI) sees broadband extremely low frequency (BBELF) waves, demonstrating significant wave-ion heating down to as low as 350 km. The e-POP Fast Auroral Imager (FAI) and Magnetic Field (MGF) instruments show that many events are associated with active aurora and are within downward current regions. Contrary to what would be expected from mirror-force acceleration of heated ions, the majority of these heating events (17 out of 24) are associated with the core ion downflow rather than upflow. These statistical results provide us with new sights into ion heating and field-aligned flow processes at very low altitudes.
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Design and simulation of ion optics for ion sources for production of singly charged ions
Zelenak, A.; Bogomolov, S. L.
2004-05-01
During the last 2 years different types of the singly charged ion sources were developed for FLNR (JINR) new projects such as Dubna radioactive ion beams, (Phase I and Phase II), the production of the tritium ion beam and the MASHA mass separator. The ion optics simulations for 2.45 GHz electron cyclotron resonance source, rf source, and the plasma ion source were performed. In this article the design and simulation results of the optics of new ion sources are presented. The results of simulation are compared with measurements obtained during the experiments.
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Design and simulation of ion optics for ion sources for production of singly charged ions
International Nuclear Information System (INIS)
Zelenak, A.; Bogomolov, S.L.
2004-01-01
During the last 2 years different types of the singly charged ion sources were developed for FLNR (JINR) new projects such as Dubna radioactive ion beams, (Phase I and Phase II), the production of the tritium ion beam and the MASHA mass separator. The ion optics simulations for 2.45 GHz electron cyclotron resonance source, rf source, and the plasma ion source were performed. In this article the design and simulation results of the optics of new ion sources are presented. The results of simulation are compared with measurements obtained during the experiments
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Crater formation by single ions, cluster ions and ion "showers"
Djurabekova, Flyura; Timko, Helga; Nordlund, Kai; Calatroni, Sergio; Taborelli, Mauro; Wuensch, Walter
2011-01-01
The various craters formed by giant objects, macroscopic collisions and nanoscale impacts exhibit an intriguing resemblance in shapes. At the same time, the arc plasma built up in the presence of sufficiently high electric fields at close look causes very similar damage on the surfaces. Although the plasma–wall interaction is far from a single heavy ion impact over dense metal surfaces or the one of a cluster ion, the craters seen on metal surfaces after a plasma discharge make it possible to link this event to the known mechanisms of the crater formations. During the plasma discharge in a high electric field the surface is subject to high fluxes (~1025 cm-2s-1) of ions with roughly equal energies typically of the order of a few keV. To simulate such a process it is possible to use a cloud of ions of the same energy. In the present work we follow the effect of such a flux of ions impinging the surface in the ‘‘shower’’ manner, to find the transition between the different mechanisms of crater formati...
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Recursos turísticos regionales: puesta en valor y desarrollo. Proyecto de investigación
Grupo Espacios Naturales y Culturales
1997-01-01
El proyecto Recursos Turísticos Regionales se inscribe en el Programa de Investigación del Centro, respecto de la problemática turística recreativa de Mar del Plata y su área turística recreativa de Mar del Plata y su área de influencia. Se realiza a través del Grupo Espacios Naturales y Culturales y dispone de subsidio de la Universidad Nacional de Mar del Plata.
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Single-ion conducting diblock terpolymers for lithium-ion batteries
Morris, Melody; Epps, Thomas H., III
Block polymer (BP) electrolytes provide an attractive route to overcome the competing constraints of high conductivity and mechanical/thermal stability in lithium-ion batteries through nanoscale self-assembly. For example, macromolecules can be engineered such that one domain conducts lithium ions and the other prevents lithium dendrite formation. Herein, we report on the behavior of a single-ion conducting BP electrolyte that was designed to facilitate the transport of lithium ions. These polymers differ from traditional salt-doped BP electrolytes, which require the addition of a lithium salt to bestow conductivity and typically suffer from substantial counterion motion that reduces efficiency. New single-ion BPs were synthesized, and the nanoscale morphologies were determined using small angle X-ray scattering and transmission electron microscopy. Electrolyte performance was measured using AC impedance spectroscopy and DC polarization, and the results were correlated to nanoscale morphology and ion content. Enhanced physical understanding of single-ion BPs was gained by connecting the ion mobility to the chemistry, chain structure, and ion content of the single-ion BP. These studies can be applied to other charged-neutral block polymers to elucidate the effects of ion content on self-assembly and macroscopic properties.
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Enhanced ion acoustic fluctuations and ion outflows
Directory of Open Access Journals (Sweden)
F. R. E. Forme
1999-02-01
Full Text Available A number of observations showing enhanced ion acoustic echoes observed by means of incoherent scatter radars have been reported in the literature. The received power is extremely enhanced by up to 1 or 2 orders of magnitude above usual values, and it is mostly contained in one of the two ion acoustic lines. This spectral asymmetry and the intensity of the received signal cannot be resolved by the standard analysis procedure and often causes its failure. As a result, and in spite of a very clear spectral signature, the analysis is unable to fit the plasma parameters inside the regions of ion acoustic turbulence. We present European Incoherent Scatter radar (EISCAT observations of large ion outflows associated with the simultaneous occurrence of enhanced ion acoustic echoes. The ion fluxes can reach 1014 m-2 s-1 at 800 km altitude. From the very clear spectral signatures of these echoes, a method is presented to extract estimates of the electron temperature and the ion drift within the turbulent regions. It is shown that the electron gas is strongly heated up to 11 000 K. Also electron temperature gradients of about 0.02 K/m exist. Finally, the estimates of the electron temperature and of the ion drift are used to study the possible implications for the plasma transport inside turbulent regions. It is shown that strong electron temperature gradients cause enhancement of the ambipolar electric field and can account for the observed ion outflows.Key words. Ionosphere (auroral ionosphere; ionosphere · magnetosphere interactions; plasma waves and instabilities.
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Directory of Open Access Journals (Sweden)
Marcos Mutuverria
2011-06-01
Full Text Available Normal 0 21 false false false MicrosoftInternetExplorer4 El presente informe manifiesta los recorridos teóricos iniciales de la tesis doctoral “Jóvenes en partidos políticos tradicionales en la región La Plata”, que se propone indagar cuál es la construcción de subjetividad, prácticas y trayectorias de los y las jóvenes pertenecientes a partidos políticos tradicionales argentinos en la ciudad de La Plata. En este sentido, el artículo refleja un mapeo en el campo de los estudios que relacionan a los jóvenes con la política (y el rol de los jóvenes en partidos políticos con las primeras consideraciones del tesista para avanzar con el análisis en sus lógicas de acción partidarias, como parte de grupalidades con disputas de poder, y en clave reflexiva sobre condiciones de género y clase en vínculo con lo etáreo al interior de los propios partidos políticos.
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Ion sources for heavy ion fusion
International Nuclear Information System (INIS)
Yu, S.S.; Eylon, S.; Chupp, W.
1995-09-01
The development of ion sources for heavy ion fusion will be reported with particular emphasis on a recently built 2 MV injector. The new injector is based on an electrostatic quadrupole configuration, and has produced pulsed K + ions of 950 mA peak from a 6.7 inch curved alumino silicate source. The ion beam has reached 2.3 MV with an energy flatness of ±0.2% over 1 micros. The measured normalized edge emittance of less than 1 π mm-mr is close to the source temperature limit. The design, construction, performance, and comparisons with three-dimensional particle-in-cell simulations will be described
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Ion-ion interaction and energy transfer of 4+ transuranium ions in cerium tetrafluoride
International Nuclear Information System (INIS)
Liu, G.K.; Beitz, J.V.
1990-01-01
Dynamics of excited 5f electron states of the transuranium ions Cm 4+ and Bk 4+ in CeF 4 are compared. Based on time- and wavelength-resolved laser-induced fluorescence, excitation energy transfer processes have been probed. Depending on concentration and electronic energy level structure of the studied 4+ transuranium ion, the dominant energy transfer mechanisms were identified as cross relaxation, exciton-exciton annihilation, and trapping. Energy transfer rates derived from the fitting of the observed fluorescence decays to theoretical models, based on electric multipolar ion-ion interactions, are contrasted with prior studies of 4f states of 3+ lanthanide and 3d states of transition metal ions. 16 refs., 1 tab
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International Nuclear Information System (INIS)
McKinney, C.R.
1980-01-01
An ion beam analyzer is specified, having an ion source for generating ions of a sample to be analyzed, means for extracting the sample ions, means for focusing the sample ions into a beam, separation means positioned along the ion beam for selectively deflecting species of ions, and means for detecting the selected species of ions. According to the specification, the analyzer further comprises (a) means for disabling at least a portion of the separation means, such that the ion beam from the source remains undeflected; (b) means located along the path of the undeflected ion beam for sensing the sample ions; and (c) enabling means responsive to the sensing means for automatically re-enabling the separation means when the sample ions reach a predetermined intensity level. (author)
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Ion acoustic solitons/double layers in two-ion plasma revisited
International Nuclear Information System (INIS)
Lakhina, G. S.; Singh, S. V.; Kakad, A. P.
2014-01-01
Ion acoustic solitons and double layers are studied in a collisionless plasma consisting of cold heavier ion species, a warm lighter ion species, and hot electrons having Boltzmann distributions by Sagdeev pseudo-potential technique. In contrast to the previous results, no double layers and super-solitons are found when both the heavy and lighter ion species are treated as cold. Only the positive potential solitons are found in this case. When the thermal effects of the lighter ion species are included, in addition to the usual ion-acoustic solitons occurring at M > 1 (where the Mach number, M, is defined as the ratio of the speed of the solitary wave and the ion-acoustic speed considering temperature of hot electrons and mass of the heavier ion species), slow ion-acoustic solitons/double layers are found to occur at low Mach number (M < 1). The slow ion-acoustic mode is actually a new ion-ion hybrid acoustic mode which disappears when the normalized number density of lighter ion species tends to 1 (i.e., no heavier species). An interesting property of the new slow ion-acoustic mode is that at low number density of the lighter ion species, only negative potential solitons/double layers are found whereas for increasing densities there is a transition first to positive solitons/double layers, and then only positive solitons. The model can be easily applicable to the dusty plasmas having positively charged dust grains by replacing the heavier ion species by the dust mass and doing a simple normalization to take account of the dust charge
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International Nuclear Information System (INIS)
Ishikawa, Junzo; Takagi, Toshinori
1983-01-01
Negative ion sources have been originally developed at the request of tandem electrostatic accelerators, and hundreds of nA to several μA negative ion current has been obtained so far for various elements. Recently, the development of large current hydrogen negative ion sources has been demanded from the standpoint of the heating by neutral particle beam injection in nuclear fusion reactors. On the other hand, the physical properties of negative ions are interesting in the thin film formation using ions. Anyway, it is the present status that the mechanism of negative ion action has not been so fully investigated as positive ions because the history of negative ion sources is short. In this report, the many mechanisms about the generation of negative ions proposed so far are described about negative ion generating mechanism, negative ion source plasma, and negative ion generation on metal surfaces. As a result, negative ion sources are roughly divided into two schemes, plasma extraction and secondary ion extraction, and the former is further classified into the PIG ion source and its variation and Duoplasmatron and its variation; while the latter into reflecting and sputtering types. In the second half of the report, the practical negative ion sources of each scheme are described. If the mechanism of negative ion generation will be investigated more in detail and the development will be continued under the unified know-how as negative ion sources in future, the development of negative ion sources with which large current can be obtained for any element is expected. (Wakatsuki, Y.)
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Experiments on Ion-Ion Plasmas From Discharges
Leonhardt, Darrin; Walton, Scott; Blackwell, David; Murphy, Donald; Fernsler, Richard; Meger, Robert
2001-10-01
Use of both positive and negative ions in plasma processing of materials has been shown to be advantageous[1] in terms of better feature evolution and control. In this presentation, experimental results are given to complement recent theoretical work[2] at NRL on the formation and decay of pulsed ion-ion plasmas in electron beam generated discharges. Temporally resolved Langmuir probe and mass spectrometry are used to investigate electron beam generated discharges during the beam on (active) and off (afterglow) phases in a variety of gas mixtures. Because electron-beam generated discharges inherently[3] have low electron temperatures (<0.5eV in molecular gases), negative ion characteristics are seen in the active as well as afterglow phases since electron detachment increases with low electron temperatures. Analysis of temporally resolved plasma characteristics deduced from these measurements will be presented for pure O_2, N2 and Ar and their mixtures with SF_6. Oxygen discharges show no noticeable negative ion contribution during the active or afterglow phase, presumably due to the higher energy electron attachment threshold, which is well above any electron temperature. In contrast, SF6 discharges demonstrate ion-ion plasma characteristics in the active glow and are completely ion-ion in the afterglow. Comparison between these discharges with published cross sections and production mechanisms will also be presented. [1] T.H. Ahn, K. Nakamura & H. Sugai, Plasma Sources Sci. Technol., 5, 139 (1996); T. Shibyama, H. Shindo & Y. Horiike, Plasma Sources Sci. Technol., 5, 254 (1996). [2] See presentation by R. F. Fernsler, at this conference. [3] D. Leonhardt, et al., 53rd Annual GEC, Houston, TX.
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Detection of gold cluster ions by ion-to-ion conversion using a CsI-converter
International Nuclear Information System (INIS)
Nguyen, V.-T.; Novilkov, A.C.; Obnorskii, V.V.
1997-01-01
Gold cluster ions in the m/z range of 10 4 -2 x 10 6 u were produced by bombarding a thin film of gold with 252 Cf-fission fragments. The gold covering a C-Al substrate formed islets having a mean diameter of 44 A. Their size- and mass-distribution was determined by means of electron microscopy. The main task was to measure the m/z distribution of the cluster ions ejected from the sample surface. For this purpose we built a time-of-flight (TOF) mass spectrometer, which could be used as a linear TOF instrument or, alternatively, as a tandem-TOF instrument being equipped with an ion-to-ion converter. Combining the results obtained in both modes, it turned out that the linear TOF instrument equipped with micro-channel plates had a mean detection efficiency for 20 keV cluster ions of about 40%. In the tandem mode, the cluster ions hit a CsI converter with energies of 40z keV (z = charge state), from where secondary ions - mainly Cs + and (CsI) n Cs + cluster ions - were ejected. These ions were used to measure the TOF spectrum of the gold cluster ions. The detection efficiency of the cluster ions was found to vary in the available mass range from 99.7% to 96.5%. The complete mass distribution between 4 x 10 4 and 4 x 10 6 u was determined and compared with the corresponding mass distribution of the gold islets covering the substrate. (orig.)
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Energy Technology Data Exchange (ETDEWEB)
Gonzaga G, V. E.
2013-07-01
Clinoptilolite zeolite material is a relative abundance in Mexico, which has ion exchange properties, therefore, has the ability to retain metal ions giving it an application in the process of disinfecting of water contaminated with pathogenic microorganisms. In this research, we conducted a study of disinfection of water contaminated with a microbial consortium, from a zeolite rock clinoptilolite from a deposit located in the State of Guerrero. Initially, the zeolite prepared by the grinding and sieving, for conditioning with NaCl and subsequently with AgNO{sub 3}, finally to be characterized using the techniques of scanning electron microscopy and X-ray diffraction. Tests using columns packed with zeolite material, the effect of zeolite bactericidal conditioned with silver (ZGAg) against a microbial consortium consisting of Escherichia coli and Sthapyloccocus aureus in aqueous solution in the presence of ammonium ions used to increase the ion exchange with zeolite fitted with silver. To describe curves disinfecting a continuous flow system is adapted Gu pta model, which describes the kinetics and equilibrium adsorption process, considering the microorganisms as the adsorbate and the sanitizing agent (conditioned with silver zeolite) as the adsorbent. Characterization results show that in the scanning electron microscopy (Sem), no changes were obtained on the morphology of typical clinoptilolite crystals before and after that was modified with sodium and then with silver, it is worth mentioning however that fitted with silver zeolite (ZGAg), small particles are seen on the zeolite material which when analyzed by energy dispersive spectroscopy (EDS), we found a high concentration of Ag +. The disinfection period is increased as the concentration increased ammonium ions, this behavior is attributed to the ion exchange that occurs between the ammonium ions and silver ions. A lower percentage of inactivation is due, therefore, to a lesser amount of money available to
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Highly Stripped Ion Sources for MeV Ion Implantation
Energy Technology Data Exchange (ETDEWEB)
Hershcovitch, Ady
2009-06-30
Original technical objectives of CRADA number PVI C-03-09 between BNL and Poole Ventura, Inc. (PVI) were to develop an intense, high charge state, ion source for MeV ion implanters. Present day high-energy ion implanters utilize low charge state (usually single charge) ion sources in combination with rf accelerators. Usually, a MV LINAC is used for acceleration of a few rnA. It is desirable to have instead an intense, high charge state ion source on a relatively low energy platform (de acceleration) to generate high-energy ion beams for implantation. This de acceleration of ions will be far more efficient (in energy utilization). The resultant implanter will be smaller in size. It will generate higher quality ion beams (with lower emittance) for fabrication of superior semiconductor products. In addition to energy and cost savings, the implanter will operate at a lower level of health risks associated with ion implantation. An additional aim of the project was to producing a product that can lead to long term job creation in Russia and/or in the US. R&D was conducted in two Russian Centers (one in Tomsk and Seversk, the other in Moscow) under the guidance ofPVI personnel and the BNL PI. Multiple approaches were pursued, developed, and tested at various locations with the best candidate for commercialization delivered and tested at on an implanter at the PVI client Axcelis. Technical developments were exciting: record output currents of high charge state phosphorus and antimony were achieved; a Calutron-Bemas ion source with a 70% output of boron ion current (compared to 25% in present state-of-the-art). Record steady state output currents of higher charge state phosphorous and antimony and P ions: P{sup 2+} (8.6 pmA), P{sup 3+} (1.9 pmA), and P{sup 4+} (0.12 pmA) and 16.2, 7.6, 3.3, and 2.2 pmA of Sb{sup 3+} Sb {sup 4 +}, Sb{sup 5+}, and Sb{sup 6+} respectively. Ultimate commercialization goals did not succeed (even though a number of the products like high
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Development of focused ion beam systems with various ion species
International Nuclear Information System (INIS)
Ji Qing; Leung, K.-N.; King, Tsu-Jae; Jiang Ximan; Appleton, Bill R.
2005-01-01
Conventional focused ion beam systems employ a liquid-metal ion source (LMIS) to generate high-brightness beams, such as Ga + beams. Recently there has been an increased need for focused ion beams in areas like biological studies, advanced magnetic-film manufacturing and secondary-ion mass spectroscopy (SIMS). In this article, status of development on focused ion beam systems with ion species such as O 2 + , P + , and B + will be reviewed. Compact columns for forming focused ion beams from low energy (∼3keV), to intermediate energy (∼35keV) are discussed. By using focused ion beams, a SOI MOSFET is fabricated entirely without any masks or resist
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Energy Technology Data Exchange (ETDEWEB)
Fischer, W.
2011-12-01
Ion colliders are research tools for high-energy nuclear physics, and are used to test the theory of Quantum Chromo Dynamics (QCD). The collisions of fully stripped high-energy ions create matter of a temperature and density that existed only microseconds after the Big Bang. Ion colliders can reach higher densities and temperatures than fixed target experiments although at a much lower luminosity. The first ion collider was the CERN Intersecting Storage Ring (ISR), which collided light ions [77Asb1, 81Bou1]. The BNL Relativistic Heavy Ion Collider (RHIC) is in operation since 2000 and has collided a number of species at numerous energies. The CERN Large Hadron Collider (LHC) started the heavy ion program in 2010. Table 1 shows all previous and the currently planned running modes for ISR, RHIC, and LHC. All three machines also collide protons, which are spin-polarized in RHIC. Ion colliders differ from proton or antiproton colliders in a number of ways: the preparation of the ions in the source and the pre-injector chain is limited by other effects than for protons; frequent changes in the collision energy and particle species, including asymmetric species, are typical; and the interaction of ions with each other and accelerator components is different from protons, which has implications for collision products, collimation, the beam dump, and intercepting instrumentation devices such a profile monitors. In the preparation for the collider use the charge state Z of the ions is successively increased to minimize the effects of space charge, intrabeam scattering (IBS), charge change effects (electron capture and stripping), and ion-impact desorption after beam loss. Low charge states reduce space charge, intrabeam scattering, and electron capture effects. High charge states reduce electron stripping, and make bending and acceleration more effective. Electron stripping at higher energies is generally more efficient. Table 2 shows the charge states and energies in the
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International Nuclear Information System (INIS)
Fischer, W.
2010-01-01
Ion colliders are research tools for high-energy nuclear physics, and are used to test the theory of Quantum Chromo Dynamics (QCD). The collisions of fully stripped high-energy ions create matter of a temperature and density that existed only microseconds after the Big Bang. Ion colliders can reach higher densities and temperatures than fixed target experiments although at a much lower luminosity. The first ion collider was the CERN Intersecting Storage Ring (ISR), which collided light ions (77Asb1, 81Bou1). The BNL Relativistic Heavy Ion Collider (RHIC) is in operation since 2000 and has collided a number of species at numerous energies. The CERN Large Hadron Collider (LHC) started the heavy ion program in 2010. Table 1 shows all previous and the currently planned running modes for ISR, RHIC, and LHC. All three machines also collide protons, which are spin-polarized in RHIC. Ion colliders differ from proton or antiproton colliders in a number of ways: the preparation of the ions in the source and the pre-injector chain is limited by other effects than for protons; frequent changes in the collision energy and particle species, including asymmetric species, are typical; and the interaction of ions with each other and accelerator components is different from protons, which has implications for collision products, collimation, the beam dump, and intercepting instrumentation devices such a profile monitors. In the preparation for the collider use the charge state Z of the ions is successively increased to minimize the effects of space charge, intrabeam scattering (IBS), charge change effects (electron capture and stripping), and ion-impact desorption after beam loss. Low charge states reduce space charge, intrabeam scattering, and electron capture effects. High charge states reduce electron stripping, and make bending and acceleration more effective. Electron stripping at higher energies is generally more efficient. Table 2 shows the charge states and energies in the
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Directory of Open Access Journals (Sweden)
Silvina Adriana Moro
2011-06-01
Full Text Available La sociedad moderna vive un intenso proceso de transformaciones sociales que, en la ciudad de La Plata, se vienen produciendo desde principios de la década de los años 90. Estas transformaciones están relacionadas con el aumento de la población y con el crecimiento urbano, resultando así necesidad de contar con espacios abiertos adecuados, que permitan el descanso, la distracción y el recreo familiar.En este sentido y desde el punto de vista del paisaje construido, la ciudad es objeto de permanentes cambios a lo largo del tiempo, que responden tanto a procesos endógenos como así también a procesos exógenos, formando parte de un proceso más amplio que se caracteriza por el acelerado crecimiento de la población urbana. Estos procesos de transformación, siempre en alguna medida afectan a la memoria de los habitantes, a las actividades del lugar y la vida colectiva de la ciudad. Son procesos complejos donde la idea es enlazar las exigencias funcionales de la ciudad de hoy con la historia de la misma ciudad. Además estos mismos procesos generalmente emplean intervenciones de carácter físico que ordenan el espacio y contribuyen con nuevas perspectivas de desarrollo.
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Fischer, W
2014-01-01
High-energy ion colliders are large research tools in nuclear physics to study the Quark-Gluon-Plasma (QGP). The range of collision energy and high luminosity are important design and operational considerations. The experiments also expect flexibility with frequent changes in the collision energy, detector fields, and ion species. Ion species range from protons, including polarized protons in RHIC, to heavy nuclei like gold, lead and uranium. Asymmetric collision combinations (e.g. protons against heavy ions) are also essential. For the creation, acceleration, and storage of bright intense ion beams, limits are set by space charge, charge change, and intrabeam scattering effects, as well as beam losses due to a variety of other phenomena. Currently, there are two operating ion colliders, the Relativistic Heavy Ion Collider (RHIC) at BNL, and the Large Hadron Collider (LHC) at CERN.
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Sathicq, María Belén; Gómez, Nora; Bauer, Delia Elena; Donadelli, Jorge
2017-11-01
Among the estuarine ecosystems under anthropogenic stress, the Río de la Plata can represent a case study to help identify phytoplanktonic species diagnosing and warning about water quality changes. The freshwater tidal zone on the coast of Argentina is used for several purposes, including recreational and navigational activities and the provision of drinking water. We analyzed the relationship between the abundance of the phytoplanktonic species, changes in water quality (linked to enrichment with nutrients and organic matter) and the land use on the coast of Argentina. A canonical correlation analysis (CCA) allowed us to identify two environmental gradients, one related to anthropogenic activities, where the most influential factors were BOD5, DIN, PO43- and DO, and a second gradient related to turbidity and conductivity. The relative abundances of 24 species were significantly correlated with the deterioration of the water quality. This set of tolerant species is mostly composed of taxa considered C-strategists, and the most represented group was the Chlorococcalean algae. The percentage of this group can provide an early warning indicator of the impairment of the water quality; its abundance exceeded 30% at those sites with a bad water quality (reaching 19000 cell mL-1), and were less than 15% (300 cell mL-1) in sites with a good water quality. The use of a reduced group of species constitutes a potential tool for monitoring, complementing another common indicators such as chlorophyll a or the total density of phytoplankton. Considering that most of these tolerant species are widely distributed it is possible to employ them as a biomonitor in other freshwater zones of temperate estuaries.
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Production of highly charged ion beams from ECR ion sources
International Nuclear Information System (INIS)
Xie, Z.Q.
1997-09-01
Electron Cyclotron Resonance (ECR) ion source development has progressed with multiple-frequency plasma heating, higher mirror magnetic fields and better technique to provide extra cold electrons. Such techniques greatly enhance the production of highly charged ions from ECR ion sources. So far at cw mode operation, up to 300 eμA of O 7+ and 1.15 emA of O 6+ , more than 100 eμA of intermediate heavy ions for charge states up to Ar 13+ , Ca 13+ , Fe 13+ , Co 14+ and Kr 18+ , and tens of eμA of heavy ions with charge states to Kr 26+ , Xe 28+ , Au 35+ , Bi 34+ and U 34+ have been produced from ECR ion sources. At an intensity of at least 1 eμA, the maximum charge state available for the heavy ions are Xe 36+ , Au 46+ , Bi 47+ and U 48+ . An order of magnitude enhancement for fully stripped argon ions (I ≥ 60 enA) also has been achieved. This article will review the ECR ion source progress and discuss key requirement for ECR ion sources to produce the highly charged ion beams
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Simionato, C. G.; Berasategui, A.; Meccia, V. L.; Acha, M.; Mianzan, H.
2008-01-01
The Río de la Plata Estuary presents a strong bottom salinity front located over a submerged shoal. Apparently favored by retention processes, it is a spawning ground for several coastal fishes. This estuary is very shallow and essentially wind driven and, moreover, in time scales relevant to biota, estuarine circulation is wind dominated and highly variable. Two intriguing questions are, therefore, how this system can favor retention and what the involved mechanisms are. This paper qualitatively explores mechanisms involved in the estuary where retention is favored applying numerical simulations in which neutral particles - simulating fish eggs and early larvae - are released along the bottom frontal zone and tracked for different wind conditions. Results suggest that retentive features can be a consequence of estuarine response to natural wind variability acting over bathymetric features. For winds from most directions, particles either remain trapped near their launching position or move northeastward to southwestward along the shoal. As alternation of winds that favor along-shoal motion is the dominant feature of wind variability in the region, a retentive scenario results from prevailing wind variability. Additionally, winds that tend to export particles with a poor chance of being restored to the front are neither frequent nor persistent. Results show, therefore, that physical forcing alone might generate a retentive scenario at the inner part of this estuary. The physical retention mechanism is more effective for bottom than for surface launched particles. Wind statistics indicate that the proposed mechanism has different implications for retention along the seasons. Spring is the most favorable season, followed by summer, when particles would have a larger propensity to reach the southern area of the estuary (Samborombón Bay). Fall and winter are increasingly less favorable. All these features are consistent with patterns observed in the region in
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Yamanaka, Takashi; Bannai, Hiroshi; Nemoto, Manabu; Tsujimura, Koji; Kondo, Takashi; Matsumura, Tomio
2011-04-01
In 2010, the World Organisation for Animal Health recommended the inclusion of a Florida sublineage clade2 strain of equine influenza virus (H3N8), which is represented by A/equine/Richmond/1/07 (Richmond07), in equine influenza vaccines. Here, we evaluate the antigenic differences between Japanese vaccine strains and Richmond07 by performing hemagglutination inhibition (HI) assays. Ferret antiserum raised to A/equine/La Plata/93 (La Plata93), which is a Japanese vaccine strain, reacted with Richmond07 at a similar titer to La Plata93. Moreover, two hundred racehorses exhibited similar geometric mean HI antibody titers against La Plata93 and Richmond07 (73.1 and 80.8, respectively). Therefore, we can expect the antibody induced by the current Japanese vaccines to provide some protection against Richmond07-like viruses.
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International Nuclear Information System (INIS)
Cocke, C.L.; Olson, R.E.
1991-01-01
The collision of a fast moving heavy ion with a neutral atomic target can produce very highly charged but slowly moving target ions. This article reviews experimental and theoretical work on the production and use of recoil ions beyond the second ionization state by beams with specific energies above 0.5 MeV/amu. A brief historical survey is followed by a discussion of theoretical approaches to the problem of the removal of many electrons from a neutral target by a rapid, multiply charged projectile. A discussion of experimental techniques and results for total and differential cross sections for multiple ionization of atomic and molecular targets is given. Measurements of recoil energy are discussed. The uses of recoil ions for in situ spectroscopy of multiply charged ions, for external beams of slow, highly charged ions and in ion traps are reviewed. Some possible future opportunities are discussed. (orig.)
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Ion Elevators and Escalators in Multilevel Structures for Lossless Ion Manipulations
Energy Technology Data Exchange (ETDEWEB)
Ibrahim, Yehia M.; Hamid, Ahmed M.; Cox, Jonathan T.; Garimella, Venkata BS; Smith, Richard D.
2017-01-19
We describe two approaches based upon ion ‘elevator’ and ‘escalator’ components that allow moving ions to different levels in structures for lossless ion manipulations (SLIM). Guided by ion motion simulations we designed elevator and escalator components providing essentially lossless transmission in multi-level designs based upon ion current measurements. The ion elevator design allowed ions to efficiently bridge a 4 mm gap between levels. The component was integrated in a SLIM and coupled to a QTOF mass spectrometer using an ion funnel interface to evaluate the m/z range transmitted as compared to transmission within a level (e.g. in a linear section). Mass spectra for singly-charged ions of m/z 600-2700 produced similar mass spectra for both elevator and straight (linear motion) components. In the ion escalator design, traveling waves (TW) were utilized to transport ions efficiently between two SLIM levels. Ion current measurements and ion mobility (IM) spectrometry analysis illustrated that ions can be transported between TW-SLIM levels with no significant loss of either ions or IM resolution. These developments provide a path for the development of multilevel designs providing e.g. much longer IM path lengths, more compact designs, and the implementation of much more complex SLIM devices in which e.g. different levels may operate at different temperatures or with different gases.
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Ion Elevators and Escalators in Multilevel Structures for Lossless Ion Manipulations.
Ibrahim, Yehia M; Hamid, Ahmed M; Cox, Jonathan T; Garimella, Sandilya V B; Smith, Richard D
2017-02-07
We describe two approaches based upon ion "elevator" and "escalator" components that allow moving ions to different levels in structures for lossless ion manipulations (SLIM). Guided by ion motion simulations, we designed elevator and escalator components based upon ion current measurements providing essentially lossless transmission in multilevel designs. The ion elevator design allowed ions to efficiently bridge a 4 mm gap between levels. The component was integrated in a SLIM and coupled to a QTOF mass spectrometer using an ion funnel interface to evaluate the m/z range transmitted as compared to transmission within a level (e.g., in a linear section). The analysis of singly charged ions of m/z 600-2700 produced similar mass spectra for both elevator and straight (linear motion) components. In the ion escalator design, traveling waves (TW) were utilized to transport ions efficiently between two SLIM levels. Ion current measurements and ion mobility (IM) spectrometry analysis illustrated that ions can be transported between TW-SLIM levels with no significant loss of either ions or IM resolution. These developments provide a path for the development of multilevel designs providing, e.g., much longer IM path lengths, more compact designs, and the implementation of much more complex SLIM devices in which, e.g., different levels may operate at different temperatures or with different gases.
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Two-dimensional boundary-value problem for ion-ion diffusion
International Nuclear Information System (INIS)
Tuszewski, M.; Lichtenberg, A.J.
1977-01-01
Like-particle diffusion is usually negligible compared with unlike-particle diffusion because it is two orders higher in spatial derivatives. When the ratio of the ion gyroradius to the plasma transverse dimension is of the order of the fourth root of the mass ratio, previous one-dimensional analysis indicated that like-particle diffusion is significant. A two-dimensional boundary-value problem for ion-ion diffusion is investigated. Numerical solutions are found with models for which the nonlinear partial differential equation reduces to an ordinary fourth-order differential equation. These solutions indicate that the ion-ion losses are higher by a factor of six for a slab geometry, and by a factor of four for circular geometry, than estimated from dimensional analysis. The solutions are applied to a multiple mirror experiment stabilized with a quadrupole magnetic field which generates highly elliptical flux surfaces. It is found that the ion-ion losses dominate the electron-ion losses and that these classical radial losses contribute to a significant decrease of plasma lifetime, in qualitiative agreement with the experimental results
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Ion Acceleration by Double Layers with Multi-Component Ion Species
Good, Timothy; Aguirre, Evan; Scime, Earl; West Virginia University Team
2017-10-01
Current-free double layers (CFDL) models have been proposed to explain observations of magnetic field-aligned ion acceleration in plasmas expanding into divergent magnetic field regions. More recently, experimental studies of the Bohm sheath criterion in multiple ion species plasma reveal an equilibration of Bohm speeds at the sheath-presheath boundary for a grounded plate in a multipole-confined filament discharge. We aim to test this ion velocity effect for CFDL acceleration. We report high resolution ion velocity distribution function (IVDF) measurements using laser induced fluorescence downstream of a CFDL in a helicon plasma. Combinations of argon-helium, argon-krypton, and argon-xenon gases are ionized and measurements of argon or xenon IVDFs are investigated to determine whether ion acceleration is enhanced (or diminished) by the presence of lighter (or heavier) ions in the mix. We find that the predominant effect is a reduction of ion acceleration consistent with increased drag arising from increased gas pressure under all conditions, including constant total gas pressure, equal plasma densities of different ions, and very different plasma densities of different ions. These results suggest that the physics responsible for acceleration of multiple ion species in simple sheaths is not responsible for the ion acceleration observed in these expanding plasmas. Department of Physics, Gettysburg College.
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A singly charged ion source for radioactive 11C ion acceleration
Katagiri, K.; Noda, A.; Nagatsu, K.; Nakao, M.; Hojo, S.; Muramatsu, M.; Suzuki, K.; Wakui, T.; Noda, K.
2016-02-01
A new singly charged ion source using electron impact ionization has been developed to realize an isotope separation on-line system for simultaneous positron emission tomography imaging and heavy-ion cancer therapy using radioactive 11C ion beams. Low-energy electron beams are used in the electron impact ion source to produce singly charged ions. Ionization efficiency was calculated in order to decide the geometric parameters of the ion source and to determine the required electron emission current for obtaining high ionization efficiency. Based on these considerations, the singly charged ion source was designed and fabricated. In testing, the fabricated ion source was found to have favorable performance as a singly charged ion source.
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International Nuclear Information System (INIS)
Coles, J.N.; Long, J.V.P.
1977-01-01
An ion microprobe is described that has an ion extraction arrangement comprising two separate paths for ions and electrons diverging from a common point. A cone shaped or pyramidal guard electrode surrounds each path the apex angles being equal and coinciding with the said point. The guard electrodes are positioned to lie tangentially to each other and to a planar surface including the said point. An aperture is provided for the two paths at the apexes of both guard electrodes, and electrical connections between the guard electrodes enable the same potential to be applied to both guard electrodes. Means are provided for generating oppositely polarised electric fields within the guard electrodes, together with means for causing a focused ion beam to strike the common point without suffering astigmatism. The means for causing a focused ion beam to strike the said point includes an ion gun for directing an ion beam along one of the paths and means to provide an axial accelerating field there along. Optical viewing means are also provided. Existing designs enable only ions or electrons, but not both, to be extracted at any one time. (U.K.)
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Ion acoustic waves in one- and two-negative ion species plasmas
International Nuclear Information System (INIS)
Ichiki, Ryuta; Shindo, Masako; Yoshimura, Shinji; Watanabe, Tsuguhiro; Kawai, Yoshinobu
2001-01-01
Ion acoustic waves in multi-ion plasmas including two negative ion species are investigated both numerically and experimentally. Numerically, the kinetic dispersion relation in two-negative ion plasmas is investigated. There are three modes of the ion acoustic waves in two-negative ion plasmas. In an Ar + -F - -SF 6 - plasma, only one of the three modes is dominant, regardless of the values of the electron and the ion temperatures. In a Xe + -F - -SF 6 - plasma, on the other hand, two modes can be important for a certain range of the electron-ion temperature ratio. The results also imply the possibility of the coexistence of the fast mode and the slow mode in one-negative ion plasmas. Experimentally, ion acoustic waves are observed in an Ar + -F - -SF 6 - plasma and are found to show a mode transition that agrees with the theoretical prediction for one of the three ion acoustic modes
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Fusion at counterstreaming ion beams - ion optic fusion (IOF)
International Nuclear Information System (INIS)
Gryzinski, M.
1981-01-01
The results of investigation are briefly reviewed in the field of ion optic fusion performed at the Institute of Nuclear Research in Swierk. The ion optic fusion concept is based on the possibility of obtaining fusion energy at highly ordered motion of ions in counterstreaming ion beams. For this purpose TW ion beams must be produced and focused. To produce dense and charge-neutralized ion beams the selective conductivity and ballistic focusing ideas were formulated and used in a series of RPI devices with low-pressure cylindrical discharge between grid-type electrodes. 100 kA, 30 keV deuteron beams were successfully produced and focused into the volume of 1 cm 3 , yielding 10 9 neutrons per 200 ns shot on a heavy ice target. Cylindrically convergent ion beams with magnetic anti-defocusing were proposed in order to reach a positive energy gain at reasonable energy level. (J.U.)
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Publications | Page 294 | IDRC - International Development ...
International Development Research Centre (IDRC) Digital Library (Canada)
Through the UFE process, and analysis of. ... Landuse change, biofuels and rural development in the La Plata Basin : country/region: La Plata River Basin ... This report assesses the land use-hydrology-soil carbon-climate interactions; it.
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Ions kinematics in an electrostatic ion beam trap
Energy Technology Data Exchange (ETDEWEB)
Attia, D
2004-06-01
In this study, I have tried to provide a better understanding of the dynamics of ions inside an electrostatic ion beam trap. The electrostatic ion trap allows to store ions moving between two electrostatic mirrors. Although the trap has been developed already seven years ago, no direct measurement of the transversal velocity distribution of the ions has been performed. Such quantity is central for understanding the conditions under which a beam should be produced (mainly emittance) in order to be trapped by such a device. The data I have obtained during the course of this work are based on an experimental technique which relies on the direct imaging of the particles exiting the trap, as well as on numerical simulations of the ion trajectories inside the trap. I have personally been involved in the hardware development of the imaging system, the data acquisition and analysis of the data as well as il all numerical calculations presented here. These results allow us to obtain, for the first time, experimental information on the transverse phase space of the trap, and contribute to the overall understanding of the ion motion in this system. (author)
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Directory of Open Access Journals (Sweden)
Sulivan Charles Barros
2015-12-01
Full Text Available As narrativas cinematográficas exercem grande poder sobre o público. Elas veiculam e constroem relações de gênero e sexualidades o que torna de extrema relevância a investigação dos discursos/práticas/efeitos do cinema na constituição de valores e representações sociais e também contribuem para delimitar os papéis dicotômicos entre homem/mulher, masculino/feminino, hetero/homo, bem como investigar abordagens que problematizem as sexualidades de forma interseccional. O cinema foi priorizado aqui como um lócus de criação marcado pela experiência das identidades de gênero e pela possibilidade de ser o cinema um recurso que possibilita a construção do conhecimento histórico, pois o cinema possui mensagens fílmicas individuais e múltiplas, mensagens que trazem valores culturais, sociais e ideológicos de uma sociedade. Neste sentido, foi analisado os filmes Plata Quemada de Marcelo Piñero e Morango e Chocolate de Tomás Gutiérrez Alea. Estes filmes, no meu entendimento, estão centrados em subjetividades queer que podem contribuir para a crítica cultural às sociedades patriarcais, machistas e sexistas, propiciando outros sentidos para o imaginário social. Buscou-se conferir também nesta pesquisa às práticas discursivas queer esboçadas em parte no cinema, embora tenha claro que elas não são lineares, nem uniformes. Palavras-Chave: Cinema; América Latina; Gênero; Sexualidades. *** Abstract: Cinematographic narratives have great power over the public. They convey and to build gender relations and sexuality which makes it extremely important to investigate the discourse / practices / film effects in the formation of values and social representations and also contribute to delimit the dichotomous roles between male / female, male / female, hetero / homo and investigate approaches that problematize the sexualities of intersectional way. The film was prioritized here as a locus of creation marked by the experience of
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Ion temperature via laser scattering on ion Bernstein waves
International Nuclear Information System (INIS)
Wurden, G.A.; Ono, M.; Wong, K.L.
1981-10-01
Hydrogen ion temperature has been measured in a warm toroidal plasma with externally launched ion Bernstein waves detected by heterodyne CO 2 laser scattering. Radial scanning of the laser beam allows precise determination of k/sub perpendicular to/ for the finite ion Larmor radius wave (ω approx. less than or equal to 2Ω/sub i/). Knowledge of the magnetic field strength and ion concentration then give a radially resolved ion temperature from the dispersion relation. Probe measurements and Doppler broadening of ArII 4806A give excellent agreement
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Diffuse ions produced by electromagnetic ion beam instabilities
International Nuclear Information System (INIS)
Winske, D.; Leroy, M.M.
1984-01-01
The evolution of the electromagnetic ions beam instability driven by the reflected ion component backstreaming away from the earth's how shock into the foreshock region is studied by means computer simulation. The linear the quasi-linear states of the instability are found to be in good agreement with known results for the resonant model propagating parallel to the beam along the magnetic field and with theory developed in this paper for the nonresonant mode, which propagates antiparallel to the beam direction. The quasi-linear stage, which produces large amplitude 8Bapprox.B, sinusoidal transverse waves and ''intermediate'' ion distribution, is terminated by a nonlinear phase in which strongly nonlinear, compressive waves and ''diffuse'' ion distributions are produced. Additional processes by which the diffuse ions are accelerated to observed high energies are not addressed. The results are discussed in terms of the ion distributions and hydromagnetic waves observed in the foreshock of the earth's bow shock and of interplanetary shocks
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Production of highly ionized recoil ions in heavy ion impact
International Nuclear Information System (INIS)
Tawara, H.; Tonuma, T.; Be, S.H.; Shibata, H.; Kase, M.; Kambara, T.; Kumagai, H.; Kohno, I.
1985-01-01
The production mechanisms of highly ionized recoil ions in energetic, highly charged heavy ion impact are compared with those in photon and electron impact. In addition to the innershell ionization processes which are important in photon and electron impact, the electron transfer processes are found to play a key role in heavy ion impact. In molecular targets are also observed highly ionized monoatomic ions which are believed to be produced through production of highly ionized molecular ions followed by prompt dissociation. The observed N 6+ ions produced in 1.05MeV/amu Ar 12+ ions on N 2 molecules are produced through, for example, N 2 12+ *→N 6+ +N 6+ process. (author)
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Ion optics in an ion source system
Energy Technology Data Exchange (ETDEWEB)
Abdel-Salam, F W; Moustafa, O A; El-Khabeary, H [Accelerators Dept, Nuclear Research Center, Atomic Energy Authority, Cairo (Egypt)
1997-12-31
An analysis of ion beams from an ion source which consisted of a hemispherical anode, a plane earthed cathode, and a focusing electrode has been carried out. The focal properties of such electrode arrangement were studied using axially symmetric fields. Axial and radial electric fields were obtained as functions of the axial distance. It was found that the radial component of the gradient of potential pushes the ions towards the axis, which indicates the convergent action of the system. The effect of voltage variation between the boundary and the focusing electrode on the position of the plasma boundary are given using the experimental data of the ion source characteristics and its geometrical parameters. The advantages of plasma diffusing outside the source through a small aperture were used by applying a potential to the focusing electrode. It was possible to extract a large ion current from the expanded plasma. The system constituted a lens with a focal length of 29.4 mm. 7 figs.
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Heavy ion beams from the new Hungarian ECR ion source
International Nuclear Information System (INIS)
Biri, S.; Valek, A.; Ditroi, F.; Koivisto, H.; Arje, J.; Stiebing, K.; Schmidt, L.
1998-01-01
The first beams of highly charged ions in Hungary were obtained in fall of 1996. The new 14.5 GHz ECR ion source of ATOMKI produced beams of multiply charged ions with remarkable intensities at first experiments. Since then, numerous further developments were carried out. An external electrondonor electrode drastically increased the plasma density and, consequently, the intensity of highly charged ions. These upgrades concentrated mainly on beams from gaseous elements and were carried out by the ECRIS team of ATOMKI. Another series of experiments - ionising from solids - however, was done in the framework of an international collaboration. The first metal ion beam has been extracted from the ECRIS in November 1997 using the known method of Metal Ions from Volatile Compounds (MIVOC). The possibility to put the MIVOC chamber inside the ion source was also tested and the dosing regulation problem of metal vapours inside the ion source was solved. As a result, beams of more than 10 μA of highly charged Fe and Ni ions were produced. (author)
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A Study of Ion-Ion Hybrid Instability in the Mixed Plasma
Directory of Open Access Journals (Sweden)
Soo-Yong Kim
1987-12-01
Full Text Available There are more oxygen ions than hydrogen ions in the auroral field zone. We consider both analytic and numerical simulation study of the heating of hydrogen and oxygen ions by auroral electrons. With the low drift speed of electron beams, the ion-ion hybrid wave becomes unstable instead of the lower hybrid wave so that a preferential heating of oxygen ions occurs.
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Directory of Open Access Journals (Sweden)
Guillermo José Colombo
2011-01-01
Full Text Available La noción de burocracia sindical es usualmente utilizada para describir el accionar de determinados líderes gremiales a los que se caracteriza como reformistas, poco democráticos, defensores de sus propios intereses y proclives a la integración con el Estado. La categoría ha sido generalmente usada más para condenar que para explicar. Este trabajo se basa en el análisis de las contiendas gremiales en un sindicato de la industria pesquera en Mar del Plata, Argentina. A través de trabajo de archivo y trabajo de campo, indagué el concepto de burocracia a partir del significado que ocupa en las batallas sindicales, en las que recurrentemente se construye al enemigo no solo como burócrata sino también como traidor.
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International Nuclear Information System (INIS)
Fabrikant, J.I.; Tobias, C.A.; Holley, W.R.; Benton, E.V.; Woodruff, K.H.; MacFarland, E.W.
1983-01-01
High energy, heavy-ion beams offer superior discrimination of tissue electron densities at very low radiation doses. This characteristic has potential for diagnostic medical imaging of neoplasms arising in the soft tissues and organs because it can detect smaller inhomogeneities than x rays. Heavy-ion imaging may also increase the accuracy of cancer radiotherapy planning involving use of accelerated charged particles. In the current physics research program of passive heavy-ion imaging, critical modulation transfer function tests are being carried out in heavy-ion projection radiography and heavy-ion computerized tomography. The research goal is to improve the heavy-ion imaging method until it reaches the limits of its theoretical resolution defined by range straggling, multiple scattering, and other factors involved in the beam quality characteristics. Clinical uses of the imaging method include the application of heavy-ion computerized tomography to heavy-ion radiotherapy planning, to the study of brain tumors and other structures of the head, and to low-dose heavy-ion projection mammography, particularly for women with dense breasts where other methods of diagnosis fail. The ions used are primarily 300 to 570 MeV/amu carbon and neon ions accelerated at the Lawrence Berkeley Laboratory Bevalac
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Ion channels versus ion pumps: the principal difference, in principle.
Gadsby, David C
2009-05-01
The incessant traffic of ions across cell membranes is controlled by two kinds of border guards: ion channels and ion pumps. Open channels let selected ions diffuse rapidly down electrical and concentration gradients, whereas ion pumps labour tirelessly to maintain the gradients by consuming energy to slowly move ions thermodynamically uphill. Because of the diametrically opposed tasks and the divergent speeds of channels and pumps, they have traditionally been viewed as completely different entities, as alike as chalk and cheese. But new structural and mechanistic information about both of these classes of molecular machines challenges this comfortable separation and forces its re-evaluation.
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Note: Ion source design for ion trap systems
Noriega, J. R.; Quevedo, M.; Gnade, B.; Vasselli, J.
2013-06-01
A small plasma (glow discharge) based ion source and circuit are described in this work. The ion source works by producing a high voltage pulsed discharge between two electrodes in a pressure range of 50-100 mTorr. A third mesh electrode is used for ion extraction. The electrodes are small stainless steel screws mounted in a MACOR ionization chamber in a linear arrangement. The electrode arrangement is driven by a circuit, design for low power operation. This design is a proof of concept intended for applications on small cylindrical ion traps.
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High-ion temperature experiments with negative-ion-based NBI in LHD
International Nuclear Information System (INIS)
Takeiri, Y.; Morita, S.; Tsumori, K.; Ikeda, K.; Oka, Y.; Osakabe, M.; Nagaoka, K.; Goto, M.; Miyazawa, J.; Masuzaki, S.; Ashikawa, N.; Yokoyama, M.; Narihara, K.; Yamada, I.; Kubo, S.; Shimozuma, T.; Inagaki, S.; Tanaka, K.; Peterson, B.J.; Ida, K.; Kaneko, O.; Komori, A.; Murakami, S.
2005-01-01
High-Z plasmas have been produced with Ar- and/or Ne-gas fuelling to increase the ion temperature in the LHD plasmas heated with the high-energy negative-ion-based NBI. Although the electron heating is dominant in the high-energy NBI heating, the direct ion heating power is much enhanced effectively in low-density plasmas due to both an increase in the beam absorption (ionisation) power and a reduction of the ion density in the high-Z plasmas. Intensive Ne- and/or Ar-glow discharge cleaning works well to suppress dilution of the high-Z plasmas with the wall-absorbed hydrogen. As a result, the ion temperature increases with an increase in the ion heating power normalized by the ion density, and reaches 10 keV. An increase in the ion temperature is also observed with an addition of the centrally focused ECRH to the low-density and high-Z NBI plasma, suggesting improvement of the ion transport. The results obtained in the high-Z plasma experiments with the high-energy NBI heating indicate that an increase in the direct ion heating power and improvement of the ion transport are essential to the ion temperature rise, and that a high-ion temperature would be obtained as well in hydrogen plasmas with low-energy positive-NBI heating which is planed in near future in LHD. (author)
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Single ion hit detection set-up for the Zagreb ion microprobe
Smith, R. W.; Karlušić, M.; Jakšić, M.
2012-04-01
Irradiation of materials by heavy ions accelerated in MV tandem accelerators may lead to the production of latent ion tracks in many insulators and semiconductors. If irradiation is performed in a high resolution microprobe facility, ion tracks can be ordered by submicrometer positioning precision. However, full control of the ion track positioning can only be achieved by a reliable ion hit detection system that should provide a trigger signal irrespectively of the type and thickness of the material being irradiated. The most useful process that can be utilised for this purpose is emission of secondary electrons from the sample surface that follows the ion impact. The status report of the set-up presented here is based on the use of a channel electron multiplier (CEM) detector mounted on an interchangable sample holder that is inserted into the chamber in a close geometry along with the sample to be irradiated. The set-up has been tested at the Zagreb ion microprobe for different ions and energies, as well as different geometrical arrangements. For energies of heavy ions below 1 MeV/amu, results show that efficient (100%) control of ion impact can be achieved only for ions heavier than silicon. The successful use of the set-up is demonstrated by production of ordered single ion tracks in a polycarbonate film and by monitoring fluence during ion microbeam patterning of Foturan glass.
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Heavy-ion radiography and heavy-ion computed tomography
International Nuclear Information System (INIS)
Fabrikant, J.I.; Holley, W.R.; McFarland, E.W.; Tobias, C.a.
1982-02-01
Heavy-ion projection and CT radiography is being developed into a safe, low-dose, noninvasive radiological procedure that can quantitate and image small density differences in human tissues. The applications to heavy-ion mammography and heavy-ion CT imaging of the brain in clinical patients suggest their potential value in cancer diagnosis
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International Nuclear Information System (INIS)
Golovin, A.V.
1991-01-01
A method of ion-ion coincidences was suggested to study the process of ion pairs formation during molecule photoionization. The principle of action of ion-ion coincidence method is based on recording of only the negative and positive ions that formed as a result of a molecule decomposition. The flowsheet of the facility of ion-ion coincidences was presented. The processes of ion pairs formation in iodine, chloroform, propyl-, n-propenyl-, tert.butyl- and benzyl-chlorides were studied. A simple model permitting to evaluate the dependence of quantum yield of ion pair formation on excitation energy was suggested
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High current vacuum arc ion source for heavy ion fusion
International Nuclear Information System (INIS)
Qi, N.; Schein, J.; Gensler, S.; Prasad, R.R.; Krishnan, M.; Brown, I.
1999-01-01
Heavy Ion fusion (HIF) is one of the approaches for the controlled thermonuclear power production. A source of heavy ions with charge states 1+ to 2+, in ∼0.5 A current beams with ∼20 micros pulse widths and ∼10 Hz repetition rates are required. Thermionic sources have been the workhorse for the HIF program to date, but suffer from sloe turn-on, heating problems for large areas, are limited to low (contact) ionization potential elements and offer relatively low ion fluxes with a charge state limited to 1+. Gas injection sources suffer from partial ionization and deleterious neutral gas effects. The above shortcomings of the thermionic ion sources can be overcome by a vacuum arc ion source. The vacuum arc ion source is a good candidate for HIF applications. It is capable of providing ions of various elements and different charge states, in short and long pulse bursts, with low emittance and high beam currents. Under a Phase-I STTR from DOE, the feasibility of the vacuum arc ion source for the HIF applications is investigated. An existing ion source at LBNL was modified to produce ∼0.5 A, ∼60 keV Gd (A∼158) ion beams. The experimental effort concentrated on beam noise reduction, pulse-to-pulse reproducibility and achieving low beam emittance at 0.5 A ion current level. Details of the source development will be reported
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Cs+ ion source for secondary ion mass spectrometry
International Nuclear Information System (INIS)
Bentz, B.L.; Weiss, H.; Liebl, H.
1981-12-01
Various types of cesium ionization sources currently used in secondary ion mass spectrometry are briefly reviewed, followed by a description of the design and performance of a novel, thermal surface ionization Cs + source developed in this laboratory. The source was evaluated for secondary ion mass spectrometry applications using the COALA ion microprobe mass analyzer. (orig.)
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Practical aspects of trapped ion mass spectrometry, 5 applications of ion trapping devices
March, Raymond E
2009-01-01
Examines ion/neutral and ion/ion reactions, ion spectroscopy, and the structural characterization of proteins and peptides using quadropole ion trap mass spectrometry, Fourier transform - ion cyclotron resonance (FT-ICR) mass spectrometry, and traveling wave ion mobility mass spectrometry.
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Energy Technology Data Exchange (ETDEWEB)
Bykovskij, Yu
1979-02-01
The characteristics a laser source of multiply-ionized ions are described with regard to the interaction of laser radiation and matter, ion energy spectrum, angular ion distribution. The amount of multiple-ionization ions is evaluated. Out of laser source applications a laser injector of multiple-ionization ions and nuclei, laser mass spectrometry, laser X-ray microradiography, and a laser neutron generators are described.
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Compact RF ion source for industrial electrostatic ion accelerator
Energy Technology Data Exchange (ETDEWEB)
Kwon, Hyeok-Jung, E-mail: hjkwon@kaeri.re.kr; Park, Sae-Hoon; Kim, Dae-Il; Cho, Yong-Sub [Korea Multi-purpose Accelerator Complex, Korea Atomic Energy Research Institute, Gyeongsangbukdo 38180 (Korea, Republic of)
2016-02-15
Korea Multi-purpose Accelerator Complex is developing a single-ended electrostatic ion accelerator to irradiate gaseous ions, such as hydrogen and nitrogen, on materials for industrial applications. ELV type high voltage power supply has been selected. Because of the limited space, electrical power, and robust operation, a 200 MHz RF ion source has been developed. In this paper, the accelerator system, test stand of the ion source, and its test results are described.
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Compact RF ion source for industrial electrostatic ion accelerator
Kwon, Hyeok-Jung; Park, Sae-Hoon; Kim, Dae-Il; Cho, Yong-Sub
2016-02-01
Korea Multi-purpose Accelerator Complex is developing a single-ended electrostatic ion accelerator to irradiate gaseous ions, such as hydrogen and nitrogen, on materials for industrial applications. ELV type high voltage power supply has been selected. Because of the limited space, electrical power, and robust operation, a 200 MHz RF ion source has been developed. In this paper, the accelerator system, test stand of the ion source, and its test results are described.
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Programmable ion mobility spectrometer: Time resolution improvement and ion counter comparison
International Nuclear Information System (INIS)
Harrison, R.G.; Wilding, R.J.
2005-01-01
Atmospheric ion mobility spectrometers operating on the aspirated electrode principle require switching of a bias voltage to select ions of different mobility. The ion spectrum can be obtained by sweeping across a set of bias voltages. If rapid temporal changes in atmospheric ion spectra are to be measured, however, such as for a balloon-carried instrument, the sweep time across the ion spectrum must be kept short. As bias voltage steps can generate saturation in the mobility spectrometer's electrometer amplifier, the electrometer recovery time limits the ion mobility spectrum sweep rate. Here, active compensation of the charge injected at a bias voltage step is used to reduce the saturation time. Further, the optimal setting of the charge compensation circuitry provides a determination of the system capacitance, a necessary calibration parameter for absolute measurements. Using laboratory air, hourly variations in ion concentrations and air conductivity found using the voltage switching system were similar to those obtained with a traditional ion counter operating at a single mobility: ion growth, however, could only be detected using the ion spectrometer
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7 CFR 457.101 - Small grains crop insurance.
2010-01-01
..., Archuleta, Conejos, Costilla, Custer, Delta, Dolores, Eagle, Garfield, Grand, La Plata, Mesa, Moffat... counties except Plymouth, Cherokee, Buena Vista, Pocahontas, Humbolt, Wright, Franklin, Butler, Black Hawk..., Grand, La Plata, Mesa, Moffat, Montezuma, Montrose, Ouray, Pitkin, Rio Blanco, Routt and San Miguel...
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Journal of Chemical Sciences | Indian Academy of Sciences
Indian Academy of Sciences (India)
Author Affiliations. L Ramajo1 R Parra1 M Reboredo1 M Castro1. Institute of Research in Materials Science and Technology (INTEMA), (CONICET - University of Mar del Plata), Juan B Justo 4302 (B7608FDQ), Mar del Plata, Argentina ...
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Development of ion-acoustic double layers through ion-acoustic fluctuations
International Nuclear Information System (INIS)
Sekar, A.N.; Saxena, Y.C.
1985-01-01
Experimental results on the formation of ion acoustic double layers resembling asymmetric ion-holes are presented. In a double plasma device, modified suitably to inject electron beam into the target plasma, modulation of the beam through step potential leads to excitation of ion-acoustic fluctuation. The ion-acoustic fluctuation, growing away from the grids separating source and target plasmas, developed into weak asymmetric ion-acoustic double layer. The observations are in qualitative agreement with theoretical models and computer simulations. (author)
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A laser ablation ion source for the FRS ion catcher
Energy Technology Data Exchange (ETDEWEB)
Rink, Ann-Kathrin; Ebert, Jens; Petrick, Martin; Reiter, Pascal [Justus Liebig Universitaet Giessen (Germany); Dickel, Timo; Geissel, Hans; Plass, Wolfgang; Scheidenberger, Christoph [Justus Liebig Universitaet Giessen (Germany); GSI, Darmstadt (Germany); Purushothamen, Sivaji [GSI, Darmstadt (Germany)
2013-07-01
The FRS Ion Catcher was developed to serve as test bench for the low energy branch of the Super FRS to slow down exotic nuclei and prepare them for further measurements/ experiments. It consists of a cryogenic stopping cell to thermalise the ions, a diagnostic unit for stopping cell characterisation and various radiofrequency quadrupole structures to guide the ions to the Multiple-Reflection Time-of-Flight Mass Spectrometer for mass measurements, α spectroscopy and isobar separation. To characterise the extraction times of the stopping cell, which is one of the main performance parameters of such a cell, a laser ablation ion source has been develped and tested. This ion source provides a sharply defined starting point of the ions for the extraction time measurement. In the future this source will provide reference ions to calibrate the mass spectrometer for accurate mass measurements.
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Bowers, Michael T
2013-01-01
Gas Phase Ion Chemistry, Volume 3: Ions and Light discusses how ions are formed by electron impact, ion-molecule reactions, or electrical discharge. This book discusses the use of light emitted by excited molecules to characterize either the chemistry that formed the excited ion, the structure of the excited ion, or both.Organized into 10 chapters, this volume begins with an overview of the extension of the classical flowing afterglow technique to include infrared and chemiluminescence and laser-induced fluorescence detection. This text then examines the experiments involving molecules that ar
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Heavy Ion Injection Into Synchrotrons, Based On Electron String Ion Sources
Donets, E E; Syresin, E M
2004-01-01
A possibility of heavy ions injection into synchrotrons is discussed on the base of two novel ion sources, which are under development JINR during last decade: 1) the electron string ion source (ESIS), which is a modified version of a conventional electron beam ion source (EBIS), working in a reflex mode of operation, and 2) the tubular electron string ion source (TESIS). The Electron String Ion Source "Krion-2" (VBLHE, JINR, Dubna) with an applied confining magnetic field of 3 T was used for injection into the superconducting JINR synchrotron - Nuclotron and during this runs the source provided a high pulse intensity of the highly charged ion beams: Ar16+
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Influence of nonelectrostatic ion-ion interactions on double-layer capacitance
Zhao, Hui
2012-11-01
Recently a Poisson-Helmholtz-Boltzmann (PHB) model [Bohinc , Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.85.031130 85, 031130 (2012)] was developed by accounting for solvent-mediated nonelectrostatic ion-ion interactions. Nonelectrostatic interactions are described by a Yukawa-like pair potential. In the present work, we modify the PHB model by adding steric effects (finite ion size) into the free energy to derive governing equations. The modified PHB model is capable of capturing both ion specificity and ion crowding. This modified model is then employed to study the capacitance of the double layer. More specifically, we focus on the influence of nonelectrostatic ion-ion interactions on charging a double layer near a flat surface in the presence of steric effects. We numerically compute the differential capacitance as a function of the voltage under various conditions. At small voltages and low salt concentrations (dilute solution), we find out that the predictions from the modified PHB model are the same as those from the classical Poisson-Boltzmann theory, indicating that nonelectrostatic ion-ion interactions and steric effects are negligible. At moderate voltages, nonelectrostatic ion-ion interactions play an important role in determining the differential capacitance. Generally speaking, nonelectrostatic interactions decrease the capacitance because of additional nonelectrostatic repulsion among excess counterions inside the double layer. However, increasing the voltage gradually favors steric effects, which induce a condensed layer with crowding of counterions near the electrode. Accordingly, the predictions from the modified PHB model collapse onto those computed by the modified Poisson-Boltzmann theory considering steric effects alone. Finally, theoretical predictions are compared and favorably agree with experimental data, in particular, in concentrated solutions, leading one to conclude that the modified PHB model adequately predicts the diffuse
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Ion beam modification of solids ion-solid interaction and radiation damage
Wesch, Werner
2016-01-01
This book presents the method of ion beam modification of solids in realization, theory and applications in a comprehensive way. It provides a review of the physical basics of ion-solid interaction and on ion-beam induced structural modifications of solids. Ion beams are widely used to modify the physical properties of materials. A complete theory of ion stopping in matter and the calculation of the energy loss due to nuclear and electronic interactions are presented including the effect of ion channeling. To explain structural modifications due to high electronic excitations, different concepts are presented with special emphasis on the thermal spike model. Furthermore, general concepts of damage evolution as a function of ion mass, ion fluence, ion flux and temperature are described in detail and their limits and applicability are discussed. The effect of nuclear and electronic energy loss on structural modifications of solids such as damage formation, phase transitions and amorphization is reviewed for ins...
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A Study on the Ion Beam Extraction using Duo-PiGatron Ion source for Vertical Type Ion Beam Facility
Energy Technology Data Exchange (ETDEWEB)
Kim, Bom Sok; Lee, Chan young; Lee, Jae Sang [KAERI, Daejeon (Korea, Republic of)
2015-05-15
In Korea Multipurpose Accelerator Complex (KOMAC), we have started ion beam service in the new beam utilization building since March this year. For various ion beam irradiation services, we are developed implanters such as metal (150keV/1mA), gaseous (200keV/5mA) and high current ion beam facility (20keV/150mA). One of the new one is a vertical type ion beam facility without acceleration tube (60keV/20mA) which is easy to install the sample. After the installation is complete, it is where you are studying the optimal ion beam extraction process. Detailed experimental results will be presented. Vertical Type Ion Beam Facility without acceleration tube of 60keV 20mA class was installed. We successfully extracted 60keV 20mA using Duo- PiGatron Ion source for Vertical Type Ion Beam Facility. Use the BPM and Faraday-cup, is being studied the optimum conditions of ion beam extraction.
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Reactions of atomic oxygen with the chlorate ion and the perchlorate ion
Anan'ev, Vladimir; Miklin, Mikhail; Kriger, Ludmila
2014-06-01
The reactions of the chlorate ion with atomic oxygen formed under photolysis of the nitrate ion introduced to potassium chlorate crystal by co-crystallization were studied by optical and infrared absorption spectroscopy. The perchlorate ion was found to form in solids as product of addition reaction of singlet atomic oxygen, formed under dissociation of the peroxynitrite ion - the product of isomerization of the excited nitrate ion. Triplet atomic oxygen does not react with the chlorate ion. The atomic oxygen formed under photolysis of the nitrate ion introduced to potassium perchlorate crystal by co-crystallization does not react with the perchlorate ion.
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Ion species stratification within strong shocks in two-ion plasmas
Keenan, Brett D.; Simakov, Andrei N.; Taitano, William T.; Chacón, Luis
2018-03-01
Strong collisional shocks in multi-ion plasmas are featured in many environments, with Inertial Confinement Fusion (ICF) experiments being one prominent example. Recent work [Keenan et al., Phys. Rev. E 96, 053203 (2017)] answered in detail a number of outstanding questions concerning the kinetic structure of steady-state, planar plasma shocks, e.g., the shock width scaling by the Mach number, M. However, it did not discuss shock-driven ion-species stratification (e.g., relative concentration modification and temperature separation). These are important effects since many recent ICF experiments have evaded explanation by standard, single-fluid, radiation-hydrodynamic (rad-hydro) numerical simulations, and shock-driven fuel stratification likely contributes to this discrepancy. Employing the state-of-the-art Vlasov-Fokker-Planck code, iFP, along with multi-ion hydro simulations and semi-analytics, we quantify the ion stratification by planar shocks with the arbitrary Mach number and the relative species concentration for two-ion plasmas in terms of ion mass and charge ratios. In particular, for strong shocks, we find that the structure of the ion temperature separation has a nearly universal character across ion mass and charge ratios. Additionally, we find that the shock fronts are enriched with the lighter ion species and the enrichment scales as M4 for M ≫ 1.
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Musso, S.
?`Qué es la Astronomía para Ciegos?. El trabajo es una adaptación en base a la escala de magnitudes de Hipparco que cambia el concepto de luz por una adaptación sonora, donde las estrellas de magnitud 6 se escuchan en 10 dB, más o menos lo que consideramos el umbral de la audición humana. Quienes no escuchan muy bien no pueden escuchar las magnitudes 6, de la misma manera que muchos de nosotros, que no poseemos una visión perfecta, no podemos observar esas mismas estrellas en el cielo (más allá de la polución). A los astros de magnitud 5 vamos a relacionarlos a un sonido en 20 dB. Y así sucesivamente. También los colores estarán representados en una convención de graves a agudos y lo mismo algunas características del cielo. Por ejemplo, la Vía Láctea se mostrará como un ``ruido", como bien nos lo hicieron ver nuestros futuros destinatarios. En Mar del Plata nos encontramos ya trabajando en un proyecto que tiene como objetivo final la construcción del Primer Planetario Acústico del Mundo, una herramienta para la enseñanza de la astronomía, un espacio para la lucha contra la discriminación del discapacitado y una posibilidad de ``ver el cielo de un modo diferente".
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Electron string ion sources for carbon ion cancer therapy accelerators
Boytsov, A. Yu.; Donets, D. E.; Donets, E. D.; Donets, E. E.; Katagiri, K.; Noda, K.; Ponkin, D. O.; Ramzdorf, A. Yu.; Salnikov, V. V.; Shutov, V. B.
2015-08-01
The type of the Electron String Ion Sources (ESIS) is considered to be the appropriate one to produce pulsed C4+ and C6+ ion beams for cancer therapy accelerators. In fact, the new test ESIS Krion-6T already now provides more than 1010 C4+ ions per pulse and about 5 × 109 C6+ ions per pulse. Such ion sources could be suitable to apply at synchrotrons. It has also been found that Krion-6T can provide more than 1011 C6+ ions per second at the 100 Hz repetition rate, and the repetition rate can be increased at the same or larger ion output per second. This makes ESIS applicable at cyclotrons as well. ESIS can be also a suitable type of ion source to produce the 11C radioactive ion beams. A specialized cryogenic cell was experimentally tested at the Krion-2M ESIS for pulse injection of gaseous species into the electron string. It has been shown in experiments with stable methane that the total conversion efficiency of methane molecules to C4+ ions reached 5%÷10%. For cancer therapy with simultaneous irradiation and precise dose control (positron emission tomography) by means of 11C, transporting to the tumor with the primary accelerated 11C4+ beam, this efficiency is preliminarily considered to be large enough to produce the 11C4+ beam from radioactive methane and to inject this beam into synchrotrons.
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Preliminary Tests of a Paul ion Trap as an Ion Source
Sadat Kiai, S. M.; Zirak, A. R.; Elahi, M.; Adlparvar, S.; Mortazavi, B. N.; Safarien, A.; Farhangi, S.; Sheibani, S.; Alhooie, S.; Khalaj, M. M. A.; Dabirzadeh, A. A.; Ruzbehani, M.; Zahedi, F.
2010-10-01
The paper reports on the design and construction of a Paul ion trap as an ion source by using an impact electron ionization technique. Ions are produced in the trap and confined for the specific time which is then extracted and detected by a Faraday cup. Especial electronic configurations are employed between the end caps, ring electrodes, electron gun and a negative voltage for the detector. This configuration allows a constant low level of pure ion source between the pulsed confined ion sources. The present experimental results are based on the production and confinement of Argon ions with good stability and repeatability, but in principle, the technique can be used for various Argon like ions.
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GANIL Workshop on Ion Sources; Journees Sources d'Ions
Energy Technology Data Exchange (ETDEWEB)
Leroy, Renan [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France)
1999-07-01
The proceedings of the GANIL Workshop on Ion Sources held at GANIL - Caen on 18-19 March 1999 contains 13 papers aiming at improving the old source operation and developing new types of sources for nuclear research and studies of ion physics. A number of reports are devoted to applications like surface treatment, ion implantation or fusion injection. The 1+{yields}n+ transformation, charged particle transport in ECR sources, addition of cesium and xenon in negative ion sources and other basic issues in ion sources are also addressed.
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Review on heavy ion radiotherapy facilities and related ion sources (invited)
International Nuclear Information System (INIS)
Kitagawa, A.; Fujita, T.; Muramatsu, M.; Biri, S.; Drentje, A. G.
2010-01-01
Heavy ion radiotherapy awakens worldwide interest recently. The clinical results obtained by the Heavy Ion Medical Accelerator in Chiba at the National Institute of Radiological Sciences in Japan have clearly demonstrated the advantages of carbon ion radiotherapy. Presently, there are four facilities for heavy ion radiotherapy in operation, and several new facilities are under construction or being planned. The most common requests for ion sources are a long lifetime and good stability and reproducibility. Sufficient intensity has been achieved by electron cyclotron resonance ion sources at the present facilities.
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International Nuclear Information System (INIS)
Gries, W.H.
1976-06-01
This is a report of the study of the implantation of heavy ions at medium keV-energies into electrically conducting mono-elemental solids, at ion doses too small to cause significant loss of the implanted ions by resputtering. The study has been undertaken to investigate the possibility of accurate portioning of matter in submicrogram quantities, with some specific applications in mind. The problem is extensively investigated both on a theoretical level and in practice. A mathematical model is developed for calculating the loss of implanted ions by resputtering as a function of the implanted ion dose and the sputtering yield. Numerical data are produced therefrom which permit a good order-of-magnitude estimate of the loss for any ion/solid combination in which the ions are heavier than the solid atoms, and for any ion energy from 10 to 300 keV. The implanted ion dose is measured by integration of the ion beam current, and equipment and techniques are described which make possible the accurate integration of an ion current in an electromagnetic isotope separator. The methods are applied to two sample cases, one being a stable isotope, the other a radioisotope. In both cases independent methods are used to show that the implantation is indeed quantitative, as predicted. At the same time the sample cases are used to demonstrate two possible applications for quantitative ion implantation, viz. firstly for the manufacture of calibration standards for instrumental micromethods of elemental trace analysis in metals, and secondly for the determination of the half-lives of long-lived radioisotopes by a specific activity method. It is concluded that the present study has advanced quantitative ion implantation to the state where it can be successfully applied to the solution of problems in other fields
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Ion-acoustic nonlinear periodic waves in electron-positron-ion plasma
International Nuclear Information System (INIS)
Chawla, J. K.; Mishra, M. K.
2010-01-01
Ion-acoustic nonlinear periodic waves, namely, ion-acoustic cnoidal waves have been studied in electron-positron-ion plasma. Using reductive perturbation method and appropriate boundary condition for nonlinear periodic waves, the Korteweg-de Vries (KdV) equation is derived for the system. The cnoidal wave solution of the KdV equation is discussed in detail. It is found that the frequency of the cnoidal wave is a function of its amplitude. It is also found that the positron concentration modifies the properties of the ion-acoustic cnoidal waves. The existence regions for ion-acoustic cnoidal wave in the parameters space (p,σ), where p and σ are the positron concentration and temperature ratio of electron to positron, are discussed in detail. In the limiting case these ion-acoustic cnoidal waves reduce to the ion-acoustic soliton solutions. The effect of other parameters on the characteristics of the nonlinear periodic waves is also discussed.
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Schmidt, B.
Ion beam techniques, including conventional broad beam ion implantation, ion beam synthesis and ion irradiation of thin layers, as well as local ion implantation with fine-focused ion beams have been applied in different fields of micro- and nanotechnology. The ion beam synthesis of nanoparticles in high-dose ion-implanted solids is explained as phase separation of nanostructures from a super-saturated solid state through precipitation and Ostwald ripening during subsequent thermal treatment of the ion-implanted samples. A special topic will be addressed to self-organization processes of nanoparticles during ion irradiation of flat and curved solid-state interfaces. As an example of silicon nanocrystal application, the fabrication of silicon nanocrystal non-volatile memories will be described. Finally, the fabrication possibilities of nanostructures, such as nanowires and chains of nanoparticles (e.g. CoSi2), by ion beam synthesis using a focused Co+ ion beam will be demonstrated and possible applications will be mentioned.
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Sympathetic cooling of ions in a hybrid atom ion trap
Energy Technology Data Exchange (ETDEWEB)
Hoeltkemeier, Bastian
2016-10-27
In this thesis the dynamics of a trapped ion immersed in a spatially localized buffer gas is investigated. For a homogeneous buffer gas, the ion's energy distribution reaches a stable equilibrium only if the mass of the buffer gas atoms is below a critical value. This limitation can be overcome by using multipole traps in combination and/or a spatially confined buffer gas. Using a generalized model for elastic collisions of the ion with the buffer gas atoms, the ion's energy distribution is numerically determined for arbitrary buffer gas distributions and trap parameters. Three regimes characterized by the respective analytic form of the ion's equilibrium energy distribution are found. One of these is a novel regime at large atom-to-ion mass ratios where the final ion temperature can tuned by adiabatically decreasing the spatial extension of the buffer gas and the effective ion trap depth (forced sympathetic cooling). The second part of the thesis presents a hybrid atom ion trap designed for sympathetic cooling of hydroxide anions. In this hybrid trap the anions are immersed in a cloud of laser cooled rubidium atoms. The translational and rovibrational temperatures of the anions is probed by photodetachment tomography and spectroscopy which shows the first ever indication of sympathetic cooling of anions by laser cooled atoms.
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Electron string ion sources for carbon ion cancer therapy accelerators
Energy Technology Data Exchange (ETDEWEB)
Boytsov, A. Yu.; Donets, D. E.; Donets, E. D.; Donets, E. E.; Ponkin, D. O.; Ramzdorf, A. Yu.; Salnikov, V. V.; Shutov, V. B. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Katagiri, K.; Noda, K. [National Institute of Radiological Science, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)
2015-08-15
The type of the Electron String Ion Sources (ESIS) is considered to be the appropriate one to produce pulsed C{sup 4+} and C{sup 6+} ion beams for cancer therapy accelerators. In fact, the new test ESIS Krion-6T already now provides more than 10{sup 10} C{sup 4+} ions per pulse and about 5 × 10{sup 9} C{sup 6+} ions per pulse. Such ion sources could be suitable to apply at synchrotrons. It has also been found that Krion-6T can provide more than 10{sup 11} C{sup 6+} ions per second at the 100 Hz repetition rate, and the repetition rate can be increased at the same or larger ion output per second. This makes ESIS applicable at cyclotrons as well. ESIS can be also a suitable type of ion source to produce the {sup 11}C radioactive ion beams. A specialized cryogenic cell was experimentally tested at the Krion-2M ESIS for pulse injection of gaseous species into the electron string. It has been shown in experiments with stable methane that the total conversion efficiency of methane molecules to C{sup 4+} ions reached 5%÷10%. For cancer therapy with simultaneous irradiation and precise dose control (positron emission tomography) by means of {sup 11}C, transporting to the tumor with the primary accelerated {sup 11}C{sup 4+} beam, this efficiency is preliminarily considered to be large enough to produce the {sup 11}C{sup 4+} beam from radioactive methane and to inject this beam into synchrotrons.
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Directory of Open Access Journals (Sweden)
María Laura Canestraro
2015-05-01
Full Text Available Apenas transcurridos tres meses de la creación del Programa Crédito Argentino del Bicentenario para la Vivienda Única Familiar, el Municipio de General Pueyrredón anuncia las tierras disponibles para comprometer en su implementación; entre ellas, el predio conocido como Canchita de los Bomberos de la ciudad de Mar del Plata. Frente a ello, se conforma un grupo de vecinos autoconvocados en defensa de su utilización como espacio público-verde, llevando a cabo diversas estrategias cuyo objetivo es evitar la construcción de viviendas en esa zona. Paralelamente, otras personas manifiestan su parecer en relación a la ejecución del programa y desarrollan prácticas que cuestionan la legitimidad de las demandas sostenidas por aquellos vecinos. El propósito del artículo es analizar las formas de apropiación simbólica que se refuerzan y/o modifican en función de la disputa; lo que Melé (2003 llama el proceso de territorialización del conflicto. Se argumenta que, aunque se produce un choque de imaginarios (Hiernaux; 2008a, emerge un imaginario dominante que logra imponerse y legitimar el uso y disfrute del espacio a su favor.
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Emission of positive oxygen ions from ion bombardment of adsorbate-covered metal surfaces
International Nuclear Information System (INIS)
Kaurin, M.G.
1989-01-01
During ion bombardment of metal surfaces, collision cascades can result in the emission of sputtered secondary ions. Recent experiments, however, have suggested that the emission of positive ions of electronegative adsorbates can result from electronic processes rather than from processes involving elastic collisions. This dissertation presents the results of experiments studying the emission of positive oxygen ions from oxygen- and carbon-monoxide-covered transition metal surfaces during bombardment by 25-250 keV ions of neon, argon, and krypton. The systems studied may be grouped into four categories. For a nickel substrate with adsorbed oxygen, the emission of positive oxygen ions proceeds through collision cascades. For titanium and niobium with adsorbed oxygen, the emission of positive oxygen ions is proportional to the primary ion velocity, consistent with emission from electronic processes; for a given primary ion velocity, the oxygen ion yield is independent of primary ion species. For substrates of molybdenum and tungsten, the oxygen yield is proportional to primary ion velocity, but the yield also depends on the primary ion species for a given primary ion velocity in a manner that is consistent with emission resulting from electronic processes. For these two groups, except for titanium, the yields during neon ion bombardment do not extrapolate (assuming linearity with primary ion velocity) to a nonzero value at zero beam velocity. The magnitude of the oxygen ion yields from these targets is not consistent with that expected if the emission were induced by secondary electrons emitted during the ion bombardment
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Systems and Methods for Ejection of Ions from an Ion Trap
Cooks, Robert Graham (Inventor); Snyder, Dalton (Inventor)
2018-01-01
The invention generally relates to systems and methods for ejection of ions from an ion trap. In certain embodiments, systems and methods of the invention sum two different frequency signals into a single summed signal that is applied to an ion trap. In other embodiments, an amplitude of a single frequency signal is modulated as the single frequency signal is being applied to the ion trap. In other embodiments, a first alternating current (AC) signal is applied to an ion trap that varies as a function of time, while a constant radio frequency (RF) signal is applied to the ion trap.
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2008-01-01
The Ion Beam Propulsion Study was a joint high-level study between the Applied Physics Laboratory operated by NASA and ASRC Aerospace at Kennedy Space Center, Florida, and Berkeley Scientific, Berkeley, California. The results were promising and suggested that work should continue if future funding becomes available. The application of ion thrusters for spacecraft propulsion is limited to quite modest ion sources with similarly modest ion beam parameters because of the mass penalty associated with the ion source and its power supply system. Also, the ion source technology has not been able to provide very high-power ion beams. Small ion beam propulsion systems were used with considerable success. Ion propulsion systems brought into practice use an onboard ion source to form an energetic ion beam, typically Xe+ ions, as the propellant. Such systems were used for steering and correction of telecommunication satellites and as the main thruster for the Deep Space 1 demonstration mission. In recent years, "giant" ion sources were developed for the controlled-fusion research effort worldwide, with beam parameters many orders of magnitude greater than the tiny ones of conventional space thruster application. The advent of such huge ion beam sources and the need for advanced propulsion systems for exploration of the solar system suggest a fresh look at ion beam propulsion, now with the giant fusion sources in mind.
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Electron-ion correlation effects in ion-atom single ionization
Energy Technology Data Exchange (ETDEWEB)
Colavecchia, F.D.; Garibotti, C.R. [Centro Atomico Bariloche and Consejo Nacional de Investigaciones Cientificas y Tecnicas, 8400 San Carlos de Bariloche (Argentina); Gasaneo, G. [Departamento de Fisica, Universidad Nacional del Sur, Av. Alem 1253, 8000 Bahia Blanca (Argentina)
2000-06-28
We study the effect of electron-ion correlation in single ionization processes of atoms by ion impact. We present a distorted wave model where the final state is represented by a correlated function solution of a non-separable three-body continuum Hamiltonian, that includes electron-ion correlation as coupling terms of the wave equation. A comparison of the electronic differential cross sections computed with this model with other theories and experimental data reveals that the influence of the electron-ion correlation is more significant for low energy emitted electrons. (author). Letter-to-the-editor.
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A quadrupole ion trap as low-energy cluster ion beam source
Uchida, N; Kanayama, T
2003-01-01
Kinetic energy distribution of ion beams was measured by a retarding field energy analyzer for a mass-selective cluster ion beam deposition system that uses a quadrupole ion trap as a cluster ion beam source. The results indicated that the system delivers a cluster-ion beam with energy distribution of approx 2 eV, which corresponded well to the calculation results of the trapping potentials in the ion trap. Using this deposition system, mass-selected hydrogenated Si cluster ions Si sub n H sub x sup + were actually deposited on Si(111)-(7x7) surfaces at impact kinetic energy E sub d of 3-30 eV. Observation by using a scanning tunneling microscope (STM) demonstrated that Si sub 6 H sub x sup + cluster ions landed on the surface without decomposition at E sub d =3 eV, while the deposition was destructive at E sub d>=18 eV. (author)
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2015-07-01
compounds by black carbon, Springer, Dordrecht. Plata, D.L., Hemingway , J.D. and Gschwend, P.M. (2015) Polyparameter linear free energy relationship for...1320-1331. 32 8. Appendices Scientific/Technical Publications Plata, D.L., J.D. Hemingway , and P.M. Gschwend. Polyparameter linear free energy
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Energy Technology Data Exchange (ETDEWEB)
Zhu, X. P. [Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024 (China); Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Zhang, Z. C.; Lei, M. K., E-mail: surfeng@dlut.edu.cn [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Pushkarev, A. I. [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Laboratory of Beam and Plasma Technology, High Technologies Physics Institute, Tomsk Polytechnic University, 30, Lenin Ave, 634050 Tomsk (Russian Federation)
2016-01-15
High-intensity pulsed ion beam (HIPIB) with ion current density above Child-Langmuir limit is achieved by extracting ion beam from anode plasma of ion diodes with suppressing electron flow under magnetic field insulation. It was theoretically estimated that with increasing the magnetic field, a maximal value of ion current density may reach nearly 3 times that of Child-Langmuir limit in a non-relativistic mode and close to 6 times in a highly relativistic mode. In this study, the behavior of ion beam enhancement by magnetic insulation is systematically investigated in three types of magnetically insulated ion diodes (MIDs) with passive anode, taking into account the anode plasma generation process on the anode surface. A maximal enhancement factor higher than 6 over the Child-Langmuir limit can be obtained in the non-relativistic mode with accelerating voltage of 200–300 kV. The MIDs differ in two anode plasma formation mechanisms, i.e., surface flashover of a dielectric coating on the anode and explosive emission of electrons from the anode, as well as in two insulation modes of external-magnetic field and self-magnetic field with either non-closed or closed drift of electrons in the anode-cathode (A-K) gap, respectively. Combined with ion current density measurement, energy density characterization is employed to resolve the spatial distribution of energy density before focusing for exploring the ion beam generation process. Consistent results are obtained on three types of MIDs concerning control of neutralizing electron flows for the space charge of ions where the high ion beam enhancement is determined by effective electron neutralization in the A-K gap, while the HIPIB composition of different ion species downstream from the diode may be considerably affected by the ion beam neutralization during propagation.
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Recharging of a screened ion on the molecular ion
International Nuclear Information System (INIS)
Karbovanets, M.I.; Lazur, V.Yu.; Yudin, G.L.; Gosudarstvennyj Komitet po Ispol'zovaniyu Atomnoj Ehnergii SSSR, Obninsk. Fiziko-Ehnergeticheskij Inst.)
1987-01-01
Charge exchange of a screened ion on a molecular ion is studied in the Oppenheimer-Brinkman-Cramers approximation. To calculate ion exchange probabilities and cross sections summed over the final degenerated electron states method of Green functions analogous to that applied earlier in the direct Coulomb excitation theory and atomic ionization is developed
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International Nuclear Information System (INIS)
Igor Kaganovich
2000-01-01
Negative ions tend to stratify in electronegative plasmas with hot electrons (electron temperature Te much larger than ion temperature Ti, Te > Ti ). The boundary separating a plasma containing negative ions, and a plasma, without negative ions, is usually thin, so that the negative ion density falls rapidly to zero-forming a negative ion density front. We review theoretical, experimental and numerical results giving the spatio-temporal evolution of negative ion density fronts during plasma ignition, the steady state, and extinction (afterglow). During plasma ignition, negative ion fronts are the result of the break of smooth plasma density profiles during nonlinear convection. In a steady-state plasma, the fronts are boundary layers with steepening of ion density profiles due to nonlinear convection also. But during plasma extinction, the ion fronts are of a completely different nature. Negative ions diffuse freely in the plasma core (no convection), whereas the negative ion front propagates towards the chamber walls with a nearly constant velocity. The concept of fronts turns out to be very effective in analysis of plasma density profile evolution in strongly non-isothermal plasmas
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Multiply charged ions from solid substances with the mVINIS Ion Source
International Nuclear Information System (INIS)
Dragani, I; Nedeljkovi, T; Jovovi, J; Siljegovic, M; Dobrosavljevic, A
2007-01-01
We have used the well known metal-ions-from-volatile-compounds (MIVOC) method at the mVINIS Ion Source to produce the multiply charged ion beams form solid substances. Based on this method the very intense and stable multiply charged ion beams of several solid substances having the high melting points were extracted. The ion yields and the spectra of multiply charged ion beams obtained from solid materials like Fe and Hf will be presented. We have utilized the multiply charged ion beams from solid substances to irradiate the polymers, fullerenes and glassy carbon at the low energy channel for modification of materials
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Ion Selectivity Mechanism in a Bacterial Pentameric Ligand-Gated Ion Channel
International Nuclear Information System (INIS)
Wang, Hailong; Cheng, Xiaolin
2011-01-01
The proton-gated ion channel from Gloeobacter violaceus (GLIC) is a prokaryotic homolog of the eukaryotic nicotinic acetylcholine receptor (nAChR) that responds to the binding of neurotransmitter acetylcholine and mediates fast signal transmission. Recent emergence of a high resolution crystal structure of GLIC captured in a potentially open state allowed detailed, atomic-level insight into ion conduction and selectivity mechanisms in these channels. Herein, we have examined the barriers to ion conduction and origins of ion selectivity in the GLIC channel by the construction of potential of mean force (PMF) profiles for sodium and chloride ions inside the transmembrane region. Our calculations reveal that the GLIC channel is open for a sodium ion to transport, but presents a ∼10 kcal/mol free energy barrier for a chloride ion, which arises primarily from the unfavorable interactions with a ring of negatively charged glutamate residues (E-2) at the intracellular end and a ring of hydrophobic residues (I9) in the middle of the transmembrane domain. Our collective findings further suggest that the charge selection mechanism can, to a large extent, be attributed to the narrow intracellular end and a ring of glutamate residues in this position their strong negative electrostatics and ability to bind cations. By contrast, E19 at the extracellular entrance only plays a minor role in ion selectivity of GLIC. In addition to electrostatics, both ion hydration and protein dynamics are found to be crucial for ion conduction as well, which explains why a chloride ion experiences a much greater barrier than a sodium ion in the hydrophobic region of the pore.
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Akter, Fouzia; Saito, Shingo; Tasaki-Handa, Yuiko; Shibukawa, Masami
2018-01-01
A new analytical methodology for a simple and efficient on-line preconcentration of trace inorganic anions in water and salt samples prior to ion chromatographic determination is proposed. The preconcentration method is based on partition/ion-exclusion chromatographic ion stacking (PIEC ion stacking) with a hydrophilic polymer gel column containing a small amount of fixed anionic charges. The developed on-line PIEC ion stacking-ion chromatography method was validated by recovery experiments for the determination of nitrate in tap water in terms of both accuracy and precision, and the results showed the reliability of the method. The method proposed was also successfully applied to the determination of trace impurity nitrite and nitrate in reagent-grade salts of sodium sulfate. A low background level can be achieved since pure water is used as the eluant for the PIEC ion stacking. It is possible to reach sensitive detection at sub-μg L -1 levels by on-line PIEC ion stacking-ion chromatography.
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Development of a compact ECR ion source for various ion production
Energy Technology Data Exchange (ETDEWEB)
Muramatsu, M., E-mail: m-mura@nirs.go.jp; Hojo, S.; Iwata, Y.; Katagiri, K.; Sakamoto, Y.; Kitagawa, A. [National Institute of Radiological Sciences (NIRS), 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan); Takahashi, N. [Sumitomo Heavy Industries, Ltd., 19 Natsushima, Yokosuka, Kanagawa 237-8555 (Japan); Sasaki, N.; Fukushima, K.; Takahashi, K.; Suzuki, T.; Sasano, T. [Accelerator Engineering Corporation, 3-8-5 Konakadai, Inage, Chiba 263-0043 (Japan); Uchida, T.; Yoshida, Y. [Bio-Nano Electronics Research Centre, Toyo University, 2100 Kujirai, Kawagoe-shi, Saitama 350-8585 (Japan); Hagino, S.; Nishiokada, T.; Kato, Y. [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita-shi, Osaka 565-0871 (Japan)
2016-02-15
There is a desire that a carbon-ion radiotherapy facility will produce various ion species for fundamental research. Although the present Kei2-type ion sources are dedicated for the carbon-ion production, a future ion source is expected that could provide: (1) carbon-ion production for medical use, (2) various ions with a charge-to-mass ratio of 1/3 for the existing Linac injector, and (3) low cost for modification. A prototype compact electron cyclotron resonance (ECR) ion source, named Kei3, based on the Kei series has been developed to correspond to the Kei2 type and to produce these various ions at the National Institute of Radiological Sciences (NIRS). The Kei3 has an outer diameter of 280 mm and a length of 1120 mm. The magnetic field is formed by the same permanent magnet as Kei2. The movable extraction electrode has been installed in order to optimize the beam extraction with various current densities. The gas-injection side of the vacuum chamber has enough space for an oven system. We measured dependence of microwave frequency, extraction voltage, and puller position. Charge state distributions of helium, carbon, nitrogen, oxygen, and neon were also measured.
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Molecular dynamics simulations of ion range profiles for heavy ions in light targets
Energy Technology Data Exchange (ETDEWEB)
Lan, C. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); State Key Laboratory of Nuclear Physics and Technology, Peking University, 100871 (China); Xue, J.M. [State Key Laboratory of Nuclear Physics and Technology, Peking University, 100871 (China); Zhang, Y., E-mail: Zhangy1@ornl.gov [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Morris, J.R. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Zhu, Z. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Gao, Y.; Wang, Y.G.; Yan, S. [State Key Laboratory of Nuclear Physics and Technology, Peking University, 100871 (China); Weber, W.J. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)
2012-09-01
The determination of stopping powers for slow heavy ions in targets containing light elements is important to accurately describe ion-solid interactions, evaluate ion irradiation effects and predict ion ranges for device fabrication and nuclear applications. Recently, discrepancies of up to 40% between the experimental results and SRIM (Stopping and Range of Ions in Matter) predictions of ion ranges for heavy ions with medium and low energies (<{approx}25 keV/nucleon) in light elemental targets have been reported. The longer experimental ion ranges indicate that the stopping powers used in the SRIM code are overestimated. Here, a molecular dynamics simulation scheme is developed to calculate the ion ranges of heavy ions in light elemental targets. Electronic stopping powers generated from both a reciprocity approach and the SRIM code are used to investigate the influence of electronic stopping on ion range profiles. The ion range profiles for Au and Pb ions in SiC and Er ions in Si, with energies between 20 and 5250 keV, are simulated. The simulation results show that the depth profiles of implanted ions are deeper and in better agreement with the experiments when using the electronic stopping power values derived from the reciprocity approach. These results indicate that the origin of the discrepancy in ion ranges between experimental results and SRIM predictions in the low energy region may be an overestimation of the electronic stopping powers used in SRIM.
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International Nuclear Information System (INIS)
Johnson, E.
1986-01-01
It is the purpose of the present paper to give a review of surface alloy processing by ion implantation. However, rather than covering this vast subject as a whole, the survey is confined to a presentation of the microstructures that can be found in metal surfaces after ion implantation. The presentation is limited to alloys processed by ion implantation proper, that is to processes in which the alloy compositions are altered significantly by direct injection of the implanted ions. The review is introduced by a presentation of the processes taking place during development of the fundamental event in ion implantation - the collision cascade, followed by a summary of the various microstructures which can be formed after ion implantation into metals. This is compared with the variability of microstructures that can be achieved by rapid solidification processing. The microstructures are subsequently discussed in the light of the processes which, as the implantations proceed, take place during and immediately after formation of the individual collision cascades. These collision cascades define the volumes inside which individual ions are slowed down in the implanted targets. They are not only centres for vigorous agitation but also the sources for formation of excess concentrations of point defects, which will influence development of particular microstructures. A final section presents a selection of specific structures which have been observed in different alloy systems. (orig./GSCH)
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Transport of negative hydrogen and deuterium ions in RF-driven ion sources
International Nuclear Information System (INIS)
Gutser, R; Wuenderlich, D; Fantz, U
2010-01-01
Negative hydrogen ion sources are major components of neutral beam injection systems for plasma heating in future large-scale fusion experiments such as ITER. In order to fulfill the requirements of the ITER neutral beam injection, a high-performance, large-area RF-driven ion source for negative ions is being developed at the MPI fuer Plasmaphysik. Negative hydrogen ions are mainly generated on a converter surface by impinging neutral particles and positive ions under the influence of magnetic fields and the plasma sheath potential. The 3D transport code TrajAn has been applied in order to obtain the total and spatially resolved extraction probabilities for H - and D - ions under identical plasma parameters and the realistic magnetic field topology of the ion source. A comparison of the isotopes shows a lower total extraction probability in the case of deuterium ions, caused by a different transport effect. The transport calculation shows that distortions of the spatial distributions of ion birth and extraction by the magnetic electron suppression field are present for both negative hydrogen and deuterium ions.
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Di Giovanni, James P; Barkley, Robert M; Jones, David N M; Hankin, Joseph A; Murphy, Robert C
2018-04-23
Ion mobility measurements of product ions were used to characterize the collisional cross section (CCS) of various complex lipid [M-H] - ions using traveling wave ion mobility mass spectrometry (TWIMS). TWIMS analysis of various product ions derived after collisional activation of mono- and dihydroxy arachidonate metabolites was found to be more complex than the analysis of intact molecular ions and provided some insight into molecular mechanisms involved in product ion formation. The CCS observed for the molecular ion [M-H] - and certain product ions were consistent with a folded ion structure, the latter predicted by the proposed mechanisms of product ion formation. Unexpectedly, product ions from [M-H-H 2 O-CO 2 ] - and [M-H-H 2 O] - displayed complex ion mobility profiles suggesting multiple mechanisms of ion formation. The [M-H-H 2 O] - ion from LTB 4 was studied in more detail using both nitrogen and helium as the drift gas in the ion mobility cell. One population of [M-H-H 2 O] - product ions from LTB 4 was consistent with formation of covalent ring structures, while the ions displaying a higher CCS were consistent with a more open-chain structure. Using molecular dynamics and theoretical CCS calculations, energy minimized structures of those product ions with the open-chain structures were found to have a higher CCS than a folded molecular ion structure. The measurement of product ion mobility can be an additional and unique signature of eicosanoids measured by LC-MS/MS techniques. Graphical Abstract ᅟ.
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Di Giovanni, James P.; Barkley, Robert M.; Jones, David N. M.; Hankin, Joseph A.; Murphy, Robert C.
2018-04-01
Ion mobility measurements of product ions were used to characterize the collisional cross section (CCS) of various complex lipid [M-H]- ions using traveling wave ion mobility mass spectrometry (TWIMS). TWIMS analysis of various product ions derived after collisional activation of mono- and dihydroxy arachidonate metabolites was found to be more complex than the analysis of intact molecular ions and provided some insight into molecular mechanisms involved in product ion formation. The CCS observed for the molecular ion [M-H]- and certain product ions were consistent with a folded ion structure, the latter predicted by the proposed mechanisms of product ion formation. Unexpectedly, product ions from [M-H-H2O-CO2]- and [M-H-H2O]- displayed complex ion mobility profiles suggesting multiple mechanisms of ion formation. The [M-H-H2O]- ion from LTB4 was studied in more detail using both nitrogen and helium as the drift gas in the ion mobility cell. One population of [M-H-H2O]- product ions from LTB4 was consistent with formation of covalent ring structures, while the ions displaying a higher CCS were consistent with a more open-chain structure. Using molecular dynamics and theoretical CCS calculations, energy minimized structures of those product ions with the open-chain structures were found to have a higher CCS than a folded molecular ion structure. The measurement of product ion mobility can be an additional and unique signature of eicosanoids measured by LC-MS/MS techniques. [Figure not available: see fulltext.
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An electron cyclotron resonance ion source based low energy ion beam platform
International Nuclear Information System (INIS)
Sun, L. T.; Shang, Y.; Ma, B. H.; Zhang, X. Z.; Feng, Y. C.; Li, X. X.; Wang, H.; Guo, X. H.; Song, M. T.; Zhao, H. Y.; Zhang, Z. M.; Zhao, H. W.; Xie, D. Z.
2008-01-01
To satisfy the requirements of surface and atomic physics study in the field of low energy multiple charge state ion incident experiments, a low energy (10 eV/q-20 keV/q) ion beam platform is under design at IMP. A simple test bench has been set up to test the ion beam deceleration systems. Considering virtues such as structure simplicity, easy handling, compactness, cost saving, etc., an all-permanent magnet ECRIS LAPECR1 [Lanzhou all-permanent magnet electron cyclotron resonance (ECR) ion source No. 1] working at 14.5 GHz has been adopted to produce intense medium and low charge state ion beams. LAPECR1 source has already been ignited. Some intense low charge state ion beams have been produced on it, but the first test also reveals that many problems are existing on the ion beam transmission line. The ion beam transmission mismatches result in the depressed performance of LAPECR1, which will be discussed in this paper. To obtain ultralow energy ion beam, after being analyzed by a double-focusing analyzer magnet, the selected ion beam will be further decelerated by two afocal deceleration lens systems, which is still under design. This design has taken into consideration both ions slowing down and also ion beam focusing. In this paper, the conceptual design of deceleration system will be discussed
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An electron cyclotron resonance ion source based low energy ion beam platform.
Sun, L T; Shang, Y; Ma, B H; Zhang, X Z; Feng, Y C; Li, X X; Wang, H; Guo, X H; Song, M T; Zhao, H Y; Zhang, Z M; Zhao, H W; Xie, D Z
2008-02-01
To satisfy the requirements of surface and atomic physics study in the field of low energy multiple charge state ion incident experiments, a low energy (10 eV/q-20 keV/q) ion beam platform is under design at IMP. A simple test bench has been set up to test the ion beam deceleration systems. Considering virtues such as structure simplicity, easy handling, compactness, cost saving, etc., an all-permanent magnet ECRIS LAPECR1 [Lanzhou all-permanent magnet electron cyclotron resonance (ECR) ion source No. 1] working at 14.5 GHz has been adopted to produce intense medium and low charge state ion beams. LAPECR1 source has already been ignited. Some intense low charge state ion beams have been produced on it, but the first test also reveals that many problems are existing on the ion beam transmission line. The ion beam transmission mismatches result in the depressed performance of LAPECR1, which will be discussed in this paper. To obtain ultralow energy ion beam, after being analyzed by a double-focusing analyzer magnet, the selected ion beam will be further decelerated by two afocal deceleration lens systems, which is still under design. This design has taken into consideration both ions slowing down and also ion beam focusing. In this paper, the conceptual design of deceleration system will be discussed.
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Ion-beam plasma and propagation of intense compensated ion beams
Energy Technology Data Exchange (ETDEWEB)
Gabovich, M D [AN Ukrainskoj SSR, Kiev. Inst. Fiziki
1977-02-01
Discussed are the results of investigation of plasma properties received by neutralization of intense ion beam space charge. Considered is the process of ion beam compensation by charges, formed as a result of gas ionization by this beam or by externally introduced ones. Emphasis is placed on collective phenomena in ion-beam plasma, in particular on non-linear effects limiting amplitude of oscillations. It is shown that not only dynamic decompensation but the Coulomb collisions of ions with electrons as well as other collective oscillations significantly affects the propagation of compensated ion beams. All the processes are to be taken into account in solving the problem of obtaining ''superdense'' compensated beams.
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Ion-beam plasma and propagation of intense compensated ion beams
International Nuclear Information System (INIS)
Gabovich, M.D.
1977-01-01
Discussed are the results of investigation of plasma properties recieved by neutralization of intensive ion beam space charge. Considered is the process of ion beam compensation by charges, formed as a result of gas ionization by this beam or by externally introduced ones. Emphasis is placed on collective phenomena in ion-beam plasma, in particular on non-linear effects limiting amplitude of oscillations. It is shown, that not only dinamic decompensation but the Coulomb collisions of ions with electrons as well as other collective oscillations significantly affects the propagation of compensated ion beams. All the processes are to be taken into account at solving the problem of obtaining ''superdense'' compensated beams
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Ion source techniques for high-speed processing of material surface by ion beams
International Nuclear Information System (INIS)
Ishikawa, Junzo
1990-01-01
The present paper discusses some key or candidate techniques for future ion source development and such ion sources developed by the author. Several types of microwave ion sources for producing low charge state ions have been developed in Japan. When a microwave plasma cathode developed by the author is adapted to a Kaufman type ion source, the electron emission currents are found to be 2.5 A for argon gas and 0.5-0.9 A for oxygen gas. An alternative ionization method for metal atoms is strongly required for high-speed processing of material surface by metal-ion beams. Detailed discussion is made of collisional ionization of vaporized atoms, and negative-ion production (secondary negative-ion emission by sputtering). An impregnated electrode type liquid-metal ion source developed by the author, which has a porous tip structure, is described. The negative-ion production efficiency is quite high. The report also presents a neutral and ionized alkaline-metal bombardment type heavy negative-ion source, which consists of a cesium plasma ion source, suppressor, target electrode, negative-ion extraction electrode, and einzel lens. (N.K.)
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Fundamental processes determining the highly charged ion production in ECR ion sources
International Nuclear Information System (INIS)
Shirkov, G.D.
1992-01-01
The ion confinement and loss conditions in the open magnetic traps have been analyzed in this article. In EGRIS the the ions are confined in the negative potential well. The simultaneous application of ion cooling and pulse regime is proposed for pulse injection of highly charged ions in heavy ion accelerators and storage rings. 14 refs.; 3 figs
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Ion-selective electrode reviews
Thomas, J D R
1983-01-01
Ion-Selective Electrode Reviews, Volume 5 is a collection of articles that covers ion-speciation. The book aims to present the advancements of the range and capabilities of selective ion-sensors. The topics covered in the selection are neutral carrier based ion-selective electrodes; reference electrodes and liquid junction effects in ion-selective electrode potentiometry; ion transfer across water/organic phase boundaries and analytical; and carbon substrate ion-selective electrodes. The text will be of great use to chemists and chemical engineers.
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Zschornacka, G.; Thorn, A.
2013-12-16
Electron beam ion sources (EBISs) are ion sources that work based on the principle of electron impact ionization, allowing the production of very highly charged ions. The ions produced can be extracted as a DC ion beam as well as ion pulses of different time structures. In comparison to most of the other known ion sources, EBISs feature ion beams with very good beam emittances and a low energy spread. Furthermore, EBISs are excellent sources of photons (X-rays, ultraviolet, extreme ultraviolet, visible light) from highly charged ions. This chapter gives an overview of EBIS physics, the principle of operation, and the known technical solutions. Using examples, the performance of EBISs as well as their applications in various fields of basic research, technology and medicine are discussed.
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ECR ion source based low energy ion beam facility
Indian Academy of Sciences (India)
Mass analyzed highly charged ion beams of energy ranging from a few keV to a few MeV plays an important role in various aspects of research in modern physics. In this paper a unique low energy ion beam facility (LEIBF) set up at Nuclear Science Centre (NSC) for providing low and medium energy multiply charged ion ...
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Lixiviación de la calcopirita en medios clorurados
Directory of Open Access Journals (Sweden)
Ibáñez, T.
2013-04-01
Full Text Available The aim of this investigation is to determinate the effects of parameters and additives on the kinetics of dissolution of chalcopyrite on moderated conditions by means of dissolutions test with chalcopyrite concentrate and pure chalcopyrite in shake flasks and instrumented stirred reactors. A study of the dissolution of chalcopyrite in chloride solutions has demonstrated that the rate of dissolution of chalcopyrite is strongly dependent on the potential of the solution within a range of 540 to 630 mV (versus SHE. Leaching at pH around 2.5 results in increased rates of copper dissolution suggesting the possibility to keep the solution potential within the range. Both pyrite and silver ions enhance the dissolution of chalcopyrite and this effect increases when both species are present. The MnO2 has a negative effect on the dissolution increasing the solution potential to values where the rate decreases considerably.El objetivo de esta investigación es determinar el efecto de parámetros y aditivos (MnO2 - iones de plata - pirita en la cinética de disolución de la calcopirita mediante pruebas de disolución con concentrado de calcopirita y calcopirita natural en matraces y reactores agitados mecánicamente bajo condiciones moderadas. La disolución de la calcopirita en medios clorurados es dependiente del potencial de la solución, obteniéndose valores de velocidad aceptables dentro de los 540 y 630 mV (SHE. El pH alrededor de los 2,5 permite mantener los potenciales de solución en valores donde la calcopirita lixivia a velocidades aceptables debido a que ocurre la precipitación de hierro. Tanto la pirita como los iones de plata catalizan la disolución y el efecto es mayor con ambas especies presentes. El MnO2 posee un efecto negativo en la disolución debido a que aumenta el potencial de la solución a valores donde la velocidad disminuye considerablemente.
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Ion-acoustic double layers in multi-species plasmas maintained by negative ions
International Nuclear Information System (INIS)
Verheest, F.
1989-01-01
A study is made of ion-acoustic double layers in a plasma consisting of any number of cold positive and negative ion (and cold electron) species in addition to one isothermal electron population. The Sagdeev potential is obtained in general, together with limits on both compressive and rarefactive solutions for ion-acoustic double layers and/or solitons. Weak ion-acoustic double layers are described by a modified Korteweg-de Vries equation. Such double layers are not possible in plasmas with only positive ion species and one electron population. When one or more negative ion and/or cold electron species are included above a certain threshold density, rarefactive ion-acoustic double layers occur, but no compressive ones. The double-layer form of the potential is given, together with an application to a plasma with one positive and one negative ion component. It is shown that there is indeed such a threshold density for the negative ion density, depending on the charge-to-mass ratios of both types of ions. The threshold density is determined numerically for a range of such ratios and discussed in view of possible relevance to auroral and experimental plasmas. In the discussion, cold electrons can play the role of the negative ion species. (author)
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An alkali ion source based on graphite intercalation compounds for ion mobility spectrometry
International Nuclear Information System (INIS)
Tabrizchi, Mahmoud; Hosseini, Zahra S
2008-01-01
A variety of alkali cation emitters were developed as the ion source for ion mobility spectrometry. The cation emitters were constructed based on alkali ion graphite intercalation compounds (GICs). The compounds were prepared by fusing alkali salts with ground graphite. In order to produce alkali ions, the compounds were loaded on a filament and heated to red. Reactant ions of the form alk + ions were observed for the alkali salts NaCl, KCl.LiCl, CsCl and SrCl. In addition to Na + ions, K + ions were observed at the beginning of thermionic emission from Na-GIC. This is due to the low ionization potential of potassium that exists in trace amounts in sodium salts. In addition to the potassium ion, Na + was observed in the case of LiCl salt. The Na + and K + peaks originating from impurities totally disappeared after about 40 min. However, the thermionic emission of the main ion of the corresponding salt lasted for several days. No negative ions were observed upon reversing the drift field. Selected organic compounds (methyl isobutyl ketone, dimethyl sulfoxide, acetone and tetrahydrofuran) were also ionized via alkali cation attachment reaction. Distinct ion mobility patterns were observed for different substances using one type of alkali reactant ion. However, the ion mobility pattern for a given substance changed when a different alkali reactant ion was used. Ammonia and amines were not ionized when this source was used
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Plasma ion sources and ion beam technology in microfabrications
International Nuclear Information System (INIS)
Ji, Lili
2007-01-01
For over decades, focused ion beam (FIB) has been playing a very important role in microscale technology and research, among which, semiconductor microfabrication is one of its biggest application area. As the dimensions of IC devices are scaled down, it has shown the need for new ion beam tools and new approaches to the fabrication of small-scale devices. In the meanwhile, nanotechnology has also deeply involved in material science research and bioresearch in recent years. The conventional FIB systems which utilize liquid gallium ion sources to achieve nanometer scale resolution can no longer meet the various requirements raised from such a wide application area such as low contamination, high throughput and so on. The drive towards controlling materials properties at nanometer length scales relies on the availability of efficient tools. In this thesis, three novel ion beam tools have been developed and investigated as the alternatives for the conventional FIB systems in some particular applications. An integrated focused ion beam (FIB) and scanning electron microscope (SEM) system has been developed for direct doping or surface modification. This new instrument employs a mini-RF driven plasma source to generate focused ion beam with various ion species, a FEI two-lens electron (2LE) column for SEM imaging, and a five-axis manipulator system for sample positioning. An all-electrostatic two-lens column has been designed to focus the ion beam extracted from the source. Based on the Munro ion optics simulation, beam spot sizes as small as 100 nm can be achieved at beam energies between 5 to 35 keV if a 5 (micro)m-diameter extraction aperture is used. Smaller beam spot sizes can be obtained with smaller apertures at sacrifice of some beam current. The FEI 2LE column, which utilizes Schottky emission, electrostatic focusing optics, and stacked-disk column construction, can provide high-resolution (as small as 20 nm) imaging capability, with fairly long working distance
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Bowers, Michael T
1979-01-01
Gas Phase Ion Chemistry, Volume 1 covers papers on the advances of gas phase ion chemistry. The book discusses the advances in flow tubes and the measurement of ion-molecule rate coefficients and product distributions; the ion chemistry of the earth's atmosphere; and the classical ion-molecule collision theory. The text also describes statistical methods in reaction dynamics; the state selection by photoion-photoelectron coincidence; and the effects of temperature and pressure in the kinetics of ion-molecule reactions. The energy distribution in the unimolecular decomposition of ions, as well
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Design of the compact ECR ion source for heavy-ion therapy
International Nuclear Information System (INIS)
Muramatsu, M.; Kitagawa, A.; Sato, S.; Sato, Y.; Yamada, S.; Hattori, T.; Shibuya, S.
1999-01-01
Heavy ion cancer treatment is successfully being done at the Heavy Ion Medical Accelerator in Chiba (HIMAC). Design philosophy for the ion sources for medical facilities are as follows: sufficient beam intensity, a few hundred eμA; long lifetime with good stability; easy operation and easy maintenance; and compactness. In order to develop such source for future heavy-ion facilities, we have tested compact electron cyclotron resonance (ECR) ion sources using permanent magnets both for axial and radial confinement of hot electrons. Since the yield of C 2+ ion in the firstly-developed source (2.45 GHz ECR) was 15 eμA and far below the medical requirement (-150 eμA for the HIMAC), a new source has been proposed, having the frequency of 10 GHz. The extracted intensity of C 4+ (and C 2+ ) ions is expected to be higher than 200 eμA. (author)
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Energy Technology Data Exchange (ETDEWEB)
Deng, Liulin; Garimella, Venkata BS; Hamid, Ahmed M.; Webb, Ian K.; Attah, Isaac K.; Norheim, Randolph V.; Prost, Spencer A.; Zheng, Xueyun; Sandoval, Jeremy A.; Baker, Erin M.; Ibrahim, Yehia M.; Smith, Richard D.
2017-05-25
We report on the implementation of a traveling wave (TW) based compression ratio ion mobility programming (CRIMP) approach within Structures for Lossless Ion Manipulations (SLIM) that enables both greatly enlarged trapped ion charge capacities and also their subsequent efficient compression for use in ion mobility (IM) separations. Ion accumulation is conducted in a long serpentine path TW SLIM region after which CRIMP allows the large ion populations to be ‘squeezed’. The compression process occurs at an interface between two SLIM regions, one operating conventionally and the second having an intermittently pausing or ‘stuttering’ TW, allowing the contents of multiple bins of ions from the first region to be merged into a single bin in the second region. In this initial work stationary voltages in the second region were used to block ions from exiting the first (trapping) region, and the resumption of TWs in the second region allows ions to exit, and the population to also be compressed if CRIMP is applied. In our initial evaluation we show that the number of charges trapped for a 40 s accumulation period was ~5×109, more than two orders of magnitude greater than the previously reported charge capacity using an ion funnel trap. We also show that over 1×109 ions can be accumulated with high efficiency in the present device, and that the extent of subsequent compression is only limited by the space charge capacity of the trapping region. Lower compression ratios allow increased IM peak heights without significant loss of signal, while excessively large compression ratios can lead to ion losses and other artifacts. Importantly, we show that extended ion accumulation in conjunction with CRIMP and multiple passes provides the basis for a highly desirable combination of ultra-high sensitivity and ultra-high resolution IM separations using SLIM.
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Fast ion-atom and ion-molecule collisions
2013-01-01
The principal goal of this book is to provide state-of-the art coverage of the non-relativistic three- and four-body theories at intermediate and high energy ion-atom and ion-molecule collisions. The focus is on the most frequently studied processes: electron capture, ionization, transfer excitation and transfer ionization. The content is suitable both for graduate students and experienced researchers. For these collisions, the literature has seen enormous renewal of activity in the development and applications of quantum-mechanical theories. This subject is of relevance in several branches of science and technology, like accelerator-based physics, the search for new sources of energy and high temperature fusion of light ions. Other important applications are in life sciences via medicine, where high-energy ion beams are used in radiotherapy for which a number of storage ring accelerators are in full operation, under construction or planned to be built worldwide. Therefore, it is necessary to review this fiel...
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Directory of Open Access Journals (Sweden)
Kota Kasahara
Full Text Available The mechanism of ion conduction by potassium channels is one of the central issues in physiology. In particular, it is still unclear how the ion concentration and the membrane voltage drive ion conduction. We have investigated the dynamics of the ion conduction processes in the Kv1.2 pore domain, by molecular dynamics (MD simulations with several different voltages and ion concentrations. By focusing on the detailed ion movements through the pore including selectivity filter (SF and cavity, we found two major conduction mechanisms, called the III-IV-III and III-II-III mechanisms, and the balance between the ion concentration and the voltage determines the mechanism preference. In the III-IV-III mechanism, the outermost ion in the pore is pushed out by a new ion coming from the intracellular fluid, and four-ion states were transiently observed. In the III-II-III mechanism, the outermost ion is pulled out first, without pushing by incoming ions. Increases in the ion concentration and voltage accelerated ion conductions, but their mechanisms were different. The increase in the ion concentrations facilitated the III-IV-III conductions, while the higher voltages increased the III-II-III conductions, indicating that the pore domain of potassium channels permeates ions by using two different driving forces: a push by intracellular ions and a pull by voltage.
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Fast-ion Dα measurements of the fast-ion distribution (invited)
International Nuclear Information System (INIS)
Heidbrink, W. W.
2010-01-01
The fast-ion Dα (FIDA) diagnostic is an application of charge-exchange recombination spectroscopy. Fast ions that neutralize in an injected neutral beam emit Balmer-α light with a large Doppler shift. The spectral shift is exploited to distinguish the FIDA emission from other bright sources of Dα light. Background subtraction is the main technical challenge. A spectroscopic diagnostic typically achieves temporal, energy, and transverse spatial resolution of ∼1 ms, ∼10 keV, and ∼2 cm, respectively. Installations that use narrow-band filters achieve high spatial and temporal resolution at the expense of spectral information. For high temporal resolution, the bandpass-filtered light goes directly to a photomultiplier, allowing detection of ∼50 kHz oscillations in FIDA signal. For two-dimensional spatial profiles, the bandpass-filtered light goes to a charge-coupled device camera; detailed images of fast-ion redistribution at instabilities are obtained. Qualitative and quantitative models relate the measured FIDA signals to the fast-ion distribution function. The first quantitative comparisons between theory and experiment found excellent agreement in beam-heated magnetohydrodynamics (MHD)-quiescent plasmas. FIDA diagnostics are now in operation at magnetic-fusion facilities worldwide. They are used to study fast-ion acceleration by ion cyclotron heating, to detect fast-ion transport by MHD modes and microturbulence, and to study fast-ion driven instabilities.
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Rearrangement reactions in ion-ion and ion-atom collisions: results and problems
Energy Technology Data Exchange (ETDEWEB)
Presnyakov, L.P. [Lebedev Physical Institute, Moscow (Russian Federation); Tawara, H.
1997-01-01
Recent experimental and theoretical results are discussed for ionic collisions with large cross sections at intermediate and small energies of the relative motion. Single- and double-electron removal from H{sup -} ions in slow collisions with other ions is considered in more details. The theoretical methods are discussed from the viewpoint of general requirements of scattering theory. (author)
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Ion-ion Recombination and Chemiion Concentrations In Aircraft Exhaust
Turco, R. P.; Yu, F.
Jet aircraft emit large quantities of ultrafine volatile aerosols, as well as soot parti- cles, into the environment. To determine the long-term effects of these emissions, a better understanding of the mechanisms that control particle formation and evolution is needed, including the number and size dispersion. A recent explanation for aerosol nucleation in a jet wake involves the condensation of sulfuric acid vapor, and cer- tain organic compounds, onto charged molecular clusters (chemiions) generated in the engine combustors (Yu and Turco, 1997). Massive charged aggregates, along with sulfuric acid and organic precursor vapors, have been detected in jet plumes under cruise conditions. In developing the chemiion nucleation theory, Yu and Turco noted that ion-ion recombination in the engine train and jet core should limit the chemiion emission index to 1017/kg-fuel. This value is consistent with ion-ion recombination coefficients of 1×10-7 cm3/s over time scales of 10-2 s. However, the evolution of the ions through the engine has not been adequately studied. The conditions at the combustor exit are extreme-temperatures approach 1500 K, and pressures can reach 30 atmospheres. In this presentation, we show that as the combustion gases expand and cool, two- and three-body ion-ion recombination processes control the chemiion concentration. The concepts of mutual neutralization and Thomson recombination are first summarized, and appropriate temperature and pressure dependent recombination rate coefficients are derived for the aircraft problem. A model for ion losses in jet exhaust is then formulated using an "invariance" principle discussed by Turco and Yu (1997) in the context of a coagulating aerosol in an expanding plume. This recombina- tion model is applied to estimate chemiion emission indices for a range of operational engine conditions. The predicted ion emission rates are found to be consistent with observations. We discuss the sources of variance in chemiion
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A heavy ion pre-injector for the ICT-ion implanter
International Nuclear Information System (INIS)
Bhattacharya, P.K.; Gaonkar, S.; Wagh, A.G.; Hattangadi, V.A.; Sarma, N.
1976-01-01
A cheap and versatile hollow cathode electron bombardment ion source system including its ion extraction-cum-focussing assembly for obtaining intense heavy ion beams of solids and gases is described. The extractor region is designed to include more than 15deg total beam angle of extracted beam for producing focused ion current densities upto 60mA/cm 2 to serve as a pre-injector for the ICT(insulated core transformer) type ion implanter. The extraction-cum-focussing lens is a low aberration strong Einzel lens system of all araldite and metal construction with optical elements of proper quality and location to suit low voltage injection and subsequent ion analysis. The injection can be selected anywhere between 2 to 10 keV for singly charged ions with typical extraction currents of 500/μ, using a ring anode and a source aperture of 20 mil. Einzel lens focussing assembly allows continuous adjustment of the beam convergence to about 5deg and the beam size to approximately 5mm in diameter with about 10 KV central electrode potential. Test results of source characteristics for both the accelerating and decelerating model of beam formation have been made. (author)
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Upgraded vacuum arc ion source for metal ion implantation
International Nuclear Information System (INIS)
Nikolaev, A. G.; Oks, E. M.; Savkin, K. P.; Yushkov, G. Yu.; Brown, I. G.
2012-01-01
Vacuum arc ion sources have been made and used by a large number of research groups around the world over the past twenty years. The first generation of vacuum arc ion sources (dubbed ''Mevva,'' for metal vapor vacuum arc) was developed at Lawrence Berkeley National Laboratory in the 1980s. This paper considers the design, performance parameters, and some applications of a new modified version of this kind of source which we have called Mevva-V.Ru. The source produces broad beams of metal ions at an extraction voltage of up to 60 kV and a time-averaged ion beam current in the milliampere range. Here, we describe the Mevva-V.Ru vacuum arc ion source that we have developed at Tomsk and summarize its beam characteristics along with some of the applications to which we have put it. We also describe the source performance using compound cathodes.
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Energy Technology Data Exchange (ETDEWEB)
Garimella, Venkata BS; Hamid, Ahmed M.; Deng, Liulin; Ibrahim, Yehia M.; Webb, Ian K.; Baker, Erin M.; Prost, Spencer A.; Norheim, Randolph V.; Anderson, Gordon A.; Smith, Richard D.
2016-11-02
In this work, we report an approach for spatial and temporal gas phase ion population manipulation, and demonstrate its application for the collapse of the ion distributions in ion mobility (IM) separations into tighter packets providing higher sensitivity measurements in conjunction with mass spectrometry (MS). We do this for ions moving from a conventionally traveling wave (TW)-driven region to a region where the TW is intermittently halted or ‘stuttered’. This approach causes the ion packets spanning a number of TW-created traveling traps (TT) to be redistributed into fewer TT, resulting in spatial compression. The degree of spatial compression is controllable and determined by the ratio of stationary time of the TW in the second region to its moving time. This compression ratio ion mobility programming (CRIMP) approach has been implemented using Structures for Lossless Ion Manipulations (SLIM) in conjunction with MS. CRIMP with the SLIM-MS platform is shown to provide increased peak intensities, reduced peak widths, and improved S/N ratios with MS detection. CRIMP also provides a foundation for extremely long path length and multi-pass IM separations in SLIM providing greatly enhanced IM resolution by reducing the detrimental effects of diffusional peak broadening due to increasing peak widths.
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Using Ion Exchange Chromatography to Separate and Quantify Complex Ions
Johnson, Brian J.
2014-01-01
Ion exchange chromatography is an important technique in the separation of charged species, particularly in biological, inorganic, and environmental samples. In this experiment, students are supplied with a mixture of two substitution-inert complex ions. They separate the complexes by ion exchange chromatography using a "flash"…
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Simulation study on ion extraction from ECR ion sources
International Nuclear Information System (INIS)
Fu, S.; Kitagawa, A.; Yamada, S.
1993-07-01
In order to study beam optics of NIRS-ECR ion source used in HIMAC, EGUN code has been modified to make it capable of modeling ion extraction from a plasma. Two versions of the modified code are worked out with two different methods in which 1-D and 2-D sheath theories are used respectively. Convergence problem of the strong nonlinear self-consistent equations is investigated. Simulations on NIRS-ECR ion source and HYPER-ECR ion source (in INS, Univ. of Tokyo) are presented in this paper, exhibiting an agreement with the experimental results. Some preliminary suggestions on the upgrading the extraction systems of these sources are also proposed. (author)
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Simulation study on ion extraction from ECR ion sources
Energy Technology Data Exchange (ETDEWEB)
Fu, S.; Kitagawa, A.; Yamada, S.
1993-07-01
In order to study beam optics of NIRS-ECR ion source used in HIMAC, EGUN code has been modified to make it capable of modeling ion extraction from a plasma. Two versions of the modified code are worked out with two different methods in which 1-D and 2-D sheath theories are used respectively. Convergence problem of the strong nonlinear self-consistent equations is investigated. Simulations on NIRS-ECR ion source and HYPER-ECR ion source (in INS, Univ. of Tokyo) are presented in this paper, exhibiting an agreement with the experimental results. Some preliminary suggestions on the upgrading the extraction systems of these sources are also proposed. (author).
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Heavy ion program at BNL: AGS, RHIC [Relativistic Heavy Ion Collider
International Nuclear Information System (INIS)
Barton, D.S.
1987-01-01
With the recent commissioning of fixed target, heavy ion physics at the AGS, Brookhaven National Laboratory (BNL) has embarked on a long range program in support of relativistic heavy ion research. Acceleration of low mass heavy ions (up to sulfur) to an energy of about 14.5 GeV/nucleon is possible with the direct connection of the BNL Tandem Van de Graaff and AGS accelerators. When completed, the new booster accelerator will provide heavy ions over the full mass range for injection and subsequent acceleration in the AGS. BNL is now engaged in an active R and D program directed toward the proposed Relativistic Heavy Ion Collider (RHIC). The results of the first operation of the low mass heavy ion program will be reviewed, and future expectations discussed. The expected performance for the heavy ion operation of the booster will be described and finally, the current status and outlook for the RHIC facility will be presented
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The heavy ion injection scheme for RHIC [Relativistic Heavy Ion Collider
International Nuclear Information System (INIS)
Rhoades-Brown, M.J.
1989-01-01
The Relativistic Heavy Ion Collider (RHIC) at Brookhaven has a multi-component injection system. The Collider requires very heavy ions such as 79 197 Au to be injected fully stripped of atomic electrons, at a kinetic energy of approximately 10 GeV/nucleon. However, the heavy ions are produced initially at a negative ion source and accelerated first in a 15 MV Tandem. These partially stripped ions have a kinetic energy of approximately 1 MeV/nucleon on leaving the Tandem. In order to achieve the injection requirements for RHIC, the partially stripped ions are accelerated in the Booster (currently under construction) and pass through a stripping foil on their way to the Alternating Gradient Synchrotron (AGS), where they are further accelerated before injection into RHIC. Recent theoretical calculations have shown quite convincingly that very heavy ions with 2 electrons in the filled K-shell may be accelerated with negligible loss in the AGS. 13 refs., 3 figs., 3 tabs
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Auroral ion beams and ion acoustic wave generation by fan instability
Energy Technology Data Exchange (ETDEWEB)
Vaivads, A
1996-04-01
Satellite observations indicate that efficient energy transport among various plasma particles and between plasma waves and plasma particles is taking place in auroral ion beam regions. These observations show that two characteristic wave types are associated with the auroral ion beam regions: electrostatic hydrogen cyclotron waves with frequencies above hydrogen gyrofrequency, and low frequency waves with frequencies below hydrogen gyrofrequency. We speculate that the low frequency waves can be ion acoustic waves generated through the fan instability. The presence of a cold background ion component is necessary for the onset of this instability. A cold ion component has been directly observed and has been indirectly suggested from observations of solitary wave structures. The wave-particle interaction during the development of the fan instability results in an efficient ion beam heating in the direction perpendicular to the ambient magnetic field. The fan instability development and the ion beam heating is demonstrated in a numerical particle simulation. 23 refs, 16 figs.
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Ion Trapping, Storage, and Ejection in Structures for Lossless Ion Manipulations.
Zhang, Xinyu; Garimella, Sandilya V B; Prost, Spencer A; Webb, Ian K; Chen, Tsung-Chi; Tang, Keqi; Tolmachev, Aleksey V; Norheim, Randolph V; Baker, Erin S; Anderson, Gordon A; Ibrahim, Yehia M; Smith, Richard D
2015-06-16
A new Structures for Lossless Ion Manipulations (SLIM) module, having electrode arrays patterned on a pair of parallel printed circuit boards (PCB), was constructed and utilized to investigate capabilities for ion trapping at a pressure of 4 Torr. Positive ions were confined by application of RF voltages to a series of inner rung electrodes with alternating phase on adjacent electrodes, in conjunction with positive DC potentials on surrounding guard electrodes on each PCB. An axial DC field was also introduced by stepwise varying the DC potentials applied to the inner rung electrodes to control the ion transport and accumulation inside the ion trapping region. We show that ions can be trapped and accumulated with up to 100% efficiency, stored for at least 5 h with no significant losses, and then could be rapidly ejected from the SLIM trap. The present results provide a foundation for the development of much more complex SLIM devices that facilitate extended ion manipulations.
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Numerical Simulation of Ion Transport in a Nano-Electrospray Ion Source at Atmospheric Pressure
Wang, Wei; Bajic, Steve; John, Benzi; Emerson, David R.
2018-03-01
Understanding ion transport properties from the ion source to the mass spectrometer (MS) is essential for optimizing device performance. Numerical simulation helps in understanding of ion transport properties and, furthermore, facilitates instrument design. In contrast to previously reported numerical studies, ion transport simulations in a continuous injection mode whilst considering realistic space-charge effects have been carried out. The flow field was solved using Reynolds-averaged Navier-Stokes (RANS) equations, and a particle-in-cell (PIC) method was applied to solve a time-dependent electric field with local charge density. A series of ion transport simulations were carried out at different cone gas flow rates, ion source currents, and capillary voltages. A force evaluation analysis reveals that the electric force, the drag force, and the Brownian force are the three dominant forces acting on the ions. Both the experimental and simulation results indicate that cone gas flow rates of ≤250 slph (standard liter per hour) are important for high ion transmission efficiency, as higher cone gas flow rates reduce the ion signal significantly. The simulation results also show that the ion transmission efficiency reduces exponentially with an increased ion source current. Additionally, the ion loss due to space-charge effects has been found to be predominant at a higher ion source current, a lower capillary voltage, and a stronger cone gas counterflow. The interaction of the ion driving force, ion opposing force, and ion dispersion is discussed to illustrate ion transport mechanism in the ion source at atmospheric pressure. [Figure not available: see fulltext.
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Development of industrial ion implantation and ion assisted coating processes: A perspective
International Nuclear Information System (INIS)
Legg, K.O.; Solnick-Legg, H.
1989-01-01
Ion beam processes have gone through a series of developmental stages, from being the mainstay of the semiconductor industry for production of integrated circuits, to new commercial processes for biomedical, aerospace and other industries. Although research is still continuing on surface modification using ion beam methods, ion implantation and ion assisted coatings for treatment of metals, ceramics, polymers and composites must now be considered viable industrial processes of benefit in a wide variety of applications. However, ion implantation methods face various barriers to acceptability, in terms not only of other surface treatment processes, but for implantation itself. This paper will discuss some of the challenges faced by a small company whose primary business is development and marketing of ion implantation and ion-assisted coating processes. (orig.)
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Fully kinetic simulation of ion acoustic and dust-ion acoustic waves
International Nuclear Information System (INIS)
Hosseini Jenab, S. M.; Kourakis, I.; Abbasi, H.
2011-01-01
A series of numerical simulations is presented, based on a recurrence-free Vlasov kinetic model using kinetic phase point trajectories. All plasma components are modeled kinetically via a Vlasov evolution equation, then coupled through Poisson's equation. The dynamics of ion acoustic waves in an electron-ion and in a dusty (electron-ion-dust) plasma configuration are investigated, focusing on wave decay due to Landau damping and, in particular, on the parametric dependence of the damping rate on the dust concentration and on the electron-to-ion temperature ratio. In the absence of dust, the occurrence of damping was observed, as expected, and its dependence to the relative magnitude of the electron vs ion temperature(s) was investigated. When present, the dust component influences the charge balance, enabling dust-ion acoustic waves to survive Landau damping even in the extreme regime where T e ≅ T i . The Landau damping rate is shown to be minimized for a strong dust concentration or/and for a high value of the electron-to-ion temperature ratio. Our results confirm earlier theoretical considerations and contribute to the interpretation of experimental observations of dust-ion acoustic wave characteristics.
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Prakrajang, K.; Sangwijit, K.; Anuntalabhochai, S.; Wanichapichart, P.; Yu, L. D.
2012-02-01
Low-energy ion beam biotechnology (IBBT) has recently been rapidly developed worldwide. Ion-beam-induced DNA transfer is one of the important applications of IBBT. However, mechanisms involved in this application are not yet well understood. In this study plasma-neutralized ion beam was applied to investigate ion charge effect on induction of DNA transfer. Argon ion beam at 7.5 keV was neutralized by RF-driven plasma in the beam path and then bombarded cellulose membranes which were used as the mimetic plant cell envelope. Electrical properties such as impedance and capacitance of the membranes were measured after the bombardment. An in vitro experiment on plasmid DNA transfer through the cellulose membrane was followed up. The results showed that the ion charge input played an important role in the impedance and capacitance changes which would affect DNA transfer. Generally speaking, neutral particle beam bombardment of biologic cells was more effective in inducing DNA transfer than charged ion beam bombardment.
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Response of thermal ions to electromagnetic ion cyclotron waves
Anderson, B. J.; Fuselier, S. A.
1994-01-01
Electromagnetic ion cyclotron waves generated by 10 - 50 keV protons in the Earth's equatorial magnetosphere will interact with the ambient low-energy ions also found in this region. We examine H(+) and He(+) distribution functions from approx. equals 1 to 160 eV using the Hot Plasma Composition Experiment instrument on AMPTE/CCE to investigate the thermal ion response to the waves. A total of 48 intervals were chosen on the basis of electromagnetic ion cyclotron (EMIC) wave activity: 24 with prevalent EMIC waves and 24 with no EMIC waves observed on the orbit. There is a close correlation between EMIC waves and perpendicular heated ion distributions. For protons the perpendicular temperature increase is modest, about 5 eV, and is always observed at 90 deg pitch angles. This is consistent with a nonresonant interaction near the equator. By contrast, He(+) temperatures during EMIC wave events averaged 35 eV and sometimes exceeded 100 eV, indicating stronger interaction with the waves. Furthermore, heated He(+) ions have X-type distributions with maximum fluxes occurring at pitch angles intermediate between field-aligned and perpendicular directions. The X-type He(+) distributions are consistent with a gyroresonant interaction off the equator. The concentration of He(+) relative to H(+) is found to correlate with EMIC wave activity, but it is suggested that the preferential heating of He(+) accounts for the apparent increase in relative He(+) concentration by increasing the proportion of He(+) detected by the ion instrument.
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International Nuclear Information System (INIS)
Nakajima, Hisao; Kohara, Shigeo; Kageyama, Tadashi; Kohno, Isao
1977-01-01
The heavy ion source, of electron bombarded hot cathode type, is usually operated by applying direct current for arc discharge. In order to accelerate Ne 6+ ion in the cyclotron, a pulsed operation of this source was attempted. Ne 6+ and O 6+ ions were accelerated successfully up to 160 MeV and more than 0.1 μA of these ion were extracted from the cyclotron. C 5+ , Ne 7+ and 22 Ne 6+ ions were also extracted with a modest intensity of beam. The intensity of C 4+ , N 4+ , N 5+ , and O 5+ ions was increased about ten times. (auth.)
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Hybrid Lithium-ion Capacitor / Lithium-ion Battery System for Extended Performance
National Aeronautics and Space Administration — The proposed task will involve the design of a hybrid power system with lithium-ion (li-ion) capacitors (LICs), li-ion batteries and solar cells. The challenge in...
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Metal negative ion beam extraction from a radio frequency ion source
Energy Technology Data Exchange (ETDEWEB)
Kanda, S.; Yamada, N.; Kasuya, T.; Romero, C. F. P.; Wada, M.
2015-04-08
A metal ion source of magnetron magnetic field geometry has been designed and operated with a Cu hollow target. Radio frequency power at 13.56 MHz is directly supplied to the hollow target to maintain plasma discharge and induce self-bias to the target for sputtering. The extraction of positive and negative Cu ion beams have been tested. The ion beam current ratio of Cu{sup +} to Ar{sup +} has reached up to 140% when Ar was used as the discharge support gas. Cu{sup −} ion beam was observed at 50 W RF discharge power and at a higher Ar gas pressure in the ion source. Improvement of poor RF power matching and suppression of electron current is indispensable for a stable Cu{sup −} ion beam production from the source.
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Ion-temperature-gradient-driven modes in bi-ion magnetoplasma
Energy Technology Data Exchange (ETDEWEB)
Batool, Nazia; Mirza, Arshad M [Theoretical Plasma Physics Group, Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Qamar, Anisa [Department of Physics, Peshawar University, NWFP 25120 (Pakistan)], E-mail: nazia.batool@ncp.edu.pk
2008-12-15
The toroidal ion-temperature-gradient (ITG)-driven electrostatic drift waves are investigated for bi-ion plasmas with equilibrium density, temperature and magnetic field gradients. Using Braginskii's transport equations for the ions and Boltzmann distributed electrons, the mode coupling equations are derived. New ITG-driven modes are shown to exist. The results of the present study should be helpful to understand several wave phenomena in space and tokamak plasmas.
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Proceedings of the 'INS workshop on ECR ion sources for multiply-charged heavy ions'
International Nuclear Information System (INIS)
1995-02-01
This workshop was held on December 1 and 2, 1994 at the Institute for Nuclear Study, University of Tokyo. The performance of ion sources is crucial for all researches and applications that use ion beam. The performance of ECR ion sources is strongly dependent on heuristic knowledge and innovation. From these viewpoints, it is useful to exchange information on the status of the existing sources, the performance of the new sources, and the design of the future sources between the source builders and the users. There were unexpected more than 70 participants and 20 contributions. The lectures were given on the present status of NIRS-ECR, SF-ECR, INS ISOL-ECR, RCNP ECR and EBIS ion sources, the production of multiply charged metallic ions with Hyper ECR or by plasma cathode method, the processing of ceramic rods and the ion production with OCTOPUS, the modeling of multi-charged ion production, the design of an advanced minimum B for ECR multi-charged ion source, the design, construction and operation of 18 GHz HiECR ion source, the construction and test operation of JAERI 18 GHz ion source, the design of an ECR ion source for the HIMAC, a 14.5 GHz ECR ion source at RIKEN, TMU 14 GHz ECR ion source, ''NANOGAN'' ECR ion source and its irradiation system, the optimization of the ECR ion source for optically pumped polarized ion source and so on. (K.I.)
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Proceedings of the `INS workshop on ECR ion sources for multiply-charged heavy ions`
Energy Technology Data Exchange (ETDEWEB)
NONE
1995-02-01
This workshop was held on December 1 and 2, 1994 at the Institute for Nuclear Study, University of Tokyo. The performance of ion sources is crucial for all researches and applications that use ion beam. The performance of ECR ion sources is strongly dependent on heuristic knowledge and innovation. From these viewpoints, it is useful to exchange information on the status of the existing sources, the performance of the new sources, and the design of the future sources between the source builders and the users. There were unexpected more than 70 participants and 20 contributions. The lectures were given on the present status of NIRS-ECR, SF-ECR, INS ISOL-ECR, RCNP ECR and EBIS ion sources, the production of multiply charged metallic ions with Hyper ECR or by plasma cathode method, the processing of ceramic rods and the ion production with OCTOPUS, the modeling of multi-charged ion production, the design of an advanced minimum B for ECR multi-charged ion source, the design, construction and operation of 18 GHz HiECR ion source, the construction and test operation of JAERI 18 GHz ion source, the design of an ECR ion source for the HIMAC, a 14.5 GHz ECR ion source at RIKEN, TMU 14 GHz ECR ion source, ``NANOGAN`` ECR ion source and its irradiation system, the optimization of the ECR ion source for optically pumped polarized ion source and so on. (K.I.).
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Specific ion effects on membrane potential and the permselectivity of ion exchange membranes.
Geise, Geoffrey M; Cassady, Harrison J; Paul, Donald R; Logan, Bruce E; Hickner, Michael A
2014-10-21
Membrane potential and permselectivity are critical parameters for a variety of electrochemically-driven separation and energy technologies. An electric potential is developed when a membrane separates electrolyte solutions of different concentrations, and a permselective membrane allows specific species to be transported while restricting the passage of other species. Ion exchange membranes are commonly used in applications that require advanced ionic electrolytes and span technologies such as alkaline batteries to ammonium bicarbonate reverse electrodialysis, but membranes are often only characterized in sodium chloride solutions. Our goal in this work was to better understand membrane behaviour in aqueous ammonium bicarbonate, which is of interest for closed-loop energy generation processes. Here we characterized the permselectivity of four commercial ion exchange membranes in aqueous solutions of sodium chloride, ammonium chloride, sodium bicarbonate, and ammonium bicarbonate. This stepwise approach, using four different ions in aqueous solution, was used to better understand how these specific ions affect ion transport in ion exchange membranes. Characterization of cation and anion exchange membrane permselectivity, using these ions, is discussed from the perspective of the difference in the physical chemistry of the hydrated ions, along with an accompanying re-derivation and examination of the basic equations that describe membrane potential. In general, permselectivity was highest in sodium chloride and lowest in ammonium bicarbonate solutions, and the nature of both the counter- and co-ions appeared to influence measured permselectivity. The counter-ion type influences the binding affinity between counter-ions and polymer fixed charge groups, and higher binding affinity between fixed charge sites and counter-ions within the membrane decreases the effective membrane charge density. As a result permselectivity decreases. The charge density and polarizability
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Space-charge compensation of highly charged ion beam from laser ion source
International Nuclear Information System (INIS)
Kondrashev, S.A.; Collier, J.; Sherwood, T.R.
1996-01-01
The problem of matching an ion beam delivered by a high-intensity ion source with an accelerator is considered. The experimental results of highly charged ion beam transport with space-charge compensation by electrons are presented. A tungsten thermionic cathode is used as a source of electrons for beam compensation. An increase of ion beam current density by a factor of 25 is obtained as a result of space-charge compensation at a distance of 3 m from the extraction system. The process of ion beam space-charge compensation, requirements for a source of electrons, and the influence of recombination losses in a space-charge-compensated ion beam are discussed. (author)
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Ion sources for initial use at the Holifield radioactive ion beam facility
International Nuclear Information System (INIS)
Alton, G.D.
1994-01-01
The Holifield Radioactive Ion Beam Facility (HRIBF) now under construction at the Oak Ridge National Laboratory will use the 25-MV tandem accelerator for the acceleration of radioactive ion beams to energies appropriate for research in nuclear physics; negative ion beams are, therefore, required for injection into the tandem accelerator. Because charge exchange is an efficient means for converting initially positive ion beams to negative ion beams, both positive and negative ion sources are viable options for use at the facility; the choice of the type of ion source will depend on the overall efficiency for generating the radioactive species of interest. A high-temperature version of the CERN-ISOLDE positive ion source has been selected and a modified version of the source designed and fabricated for initial use at the HRIBF because of its low emittance, relatively high ionization efficiencies and species versatility, and because it has been engineered for remote installation, removal and servicing as required for safe handling in a high-radiation-level ISOL facility. Prototype plasma-sputter negative ion sources and negative surfaceionization sources are also under design consideration for generating negative radioactive ion beams from high electron-affinity elements. A brief review of the HRIBF will be presented, followed by a detailed description of the design features, operational characteristics, ionization efficiencies, and beam qualities (emittances) of these sources
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Evaluation of Negative-Ion-Beam Driver Concepts for Heavy Ion Fusion
International Nuclear Information System (INIS)
Grisham, Larry R.
2002-01-01
We evaluate the feasibility of producing and using atomically neutral heavy ion beams produced from negative ions as drivers for an inertial confinement fusion reactor. Bromine and iodine appear to be the most attractive elements for the driver beams. Fluorine and chlorine appear to be the most appropriate feedstocks for initial tests of extractable negative ion current densities. With regards to ion sources, photodetachment neutralizers, and vacuum requirements for accelerators and beam transport, this approach appears feasible within existing technology, and the vacuum requirements are essentially identical to those for positive ion drivers except in the target chamber. The principal constraint is that this approach requires harder vacuums in the target chamber than do space-charge-neutralized positive ion drivers. With realistic (but perhaps pessimistic) estimates of the total ionization cross section, limiting the ionization of a neutral beam to less than 5% while traversing a four -meter path would require a chamber pressure of no more than 5 x 10 -5 torr. Alternatively, even at chamber pressures that are too high to allow propagation of atomically neutral beams, the negative ion approach may still have appeal, since it precludes the possibly serious problem of electron contamination of a positive ion beam during acceleration, drift compression, and focusing
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The ion polytropic coefficient in a collisionless sheath containing hot ions
Energy Technology Data Exchange (ETDEWEB)
Lin, Binbin; Xiang, Nong, E-mail: xiangn@ipp.ac.cn; Ou, Jing [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Center for Magnetic Fusion Theory, Chinese Academy of Sciences, Hefei 230031 (China)
2016-08-15
The fluid approach has been widely used to study plasma sheath dynamics. For a sheath containing hot ions whose temperature is greater than the electron's, how to truncate the fluid hierarchy chain equations while retaining to the fullest extent of the kinetic effects is always a difficult problem. In this paper, a one-dimensional, collisionless sheath containing hot ions is studied via particle-in-cell simulations. By analyzing the ion energy equation and taking the kinetic effects into account, we have shown that the ion polytropic coefficient in the vicinity of the sheath edge is approximately constant so that the state equation with the modified polytropic coefficient can be used to close the hierarchy chain of the ion fluid equations. The value of the polytropic coefficient strongly depends on the hot ion temperature and its concentration in the plasma. The semi-analytical model is given to interpret the simulation results. As an application, the kinetic effects on the ion saturation current density in the probe theory are discussed.
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Eiceman, GA
2005-01-01
Key Developments for Faster, More Precise Detection Capabilities Driven by the demand for the rapid and advanced detection of explosives, chemical and biological warfare agents, and narcotics, ion mobility spectrometry (IMS) undergone significant refinements in technology, computational capabilities, and understanding of the principles of gas phase ion chemistry and mobility. Beginning with a thorough discussion of the fundamental theories and physics of ion mobility, Ion Mobility Spectrometry, Second Edition describes the recent advances in instrumentation and newly
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Duopigatron ion source studies
International Nuclear Information System (INIS)
Bacon, F.M.; Bickes, R.W. Jr.; O'Hagan, J.B.
1978-07-01
Ion source performance characteristics consisting of total ion current, ion energy distribution, mass distribution, and ion current density distribution were measured for several models of a duopigatron. Variations on the duopigatron design involved plasma expansion cup material and dimensions, secondary cathode material, and interelectrode spacings. Of the designs tested, the one with a copper and molybdenum secondary cathode and a mild steel plasma expansion cup proved to give the best results. The ion current density distribution was peaked at the center of the plasma expansion cup and fell off to 80 percent of the peak value at the cup wall for a cup 15.2 mm deep. A total ion current of 180 mA consisting of 60 to 70 percent atomic ions was produced with an arc current of 20 A and source pressure of 9.3 Pa. More shallow cups produced a larger beam current and a more sharply peaked ion current density distribution. Typical ion energy distributions were bell-shaped curves with a peak 10 to 20 V below anode potential and with ion energies extending 30 to 40 V on either side of the peak
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C-terminal peptide extension via gas-phase ion/ion reactions
Peng, Zhou; McLuckey, Scott A.
2015-01-01
The formation of peptide bonds is of great importance from both a biological standpoint and in routine organic synthesis. Recent work from our group demonstrated the synthesis of peptides in the gas-phase via ion/ion reactions with sulfo-NHS reagents, which resulted in conjugation of individual amino acids or small peptides to the N-terminus of an existing ‘anchor’ peptide. Here, we demonstrate a complementary approach resulting in the C-terminal extension of peptides. Individual amino acids or short peptides can be prepared as reagents by incorporating gas phase-labile protecting groups to the reactive C-terminus and then converting the N-terminal amino groups to the active ketenimine reagent. Gas-phase ion/ion reactions between the anionic reagents and doubly protonated “anchor” peptide cations results in extension of the “anchor” peptide with new amide bond formation at the C-terminus. We have demonstrated that ion/ion reactions can be used as a fast, controlled, and efficient means for C-terminal peptide extension in the gas phase. PMID:26640400
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Cobalt alloy ion sources for focused ion beam implantation
Energy Technology Data Exchange (ETDEWEB)
Muehle, R.; Doebeli, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Zimmermann, P. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)
1997-09-01
Cobalt alloy ion sources have been developed for silicide formation by focused ion beam implantation. Four eutectic alloys AuCo, CoGe, CoY and AuCoGe were produced by electron beam welding. The AuCo liquid alloy ion source was investigated in detail. We have measured the emission current stability, the current-voltage characteristics, and the mass spectrum as a function of the mission current. (author) 1 fig., 2 refs.
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Studies on indigenous ion exchange resins: alkali metal ions-hydrogen ion exchange equilibria
International Nuclear Information System (INIS)
Shankar, S.; Kumar, Surender; Venkataramani, B.
2001-01-01
With a view to select a suitable ion exchange resin for the removal of radionuclides (such as cesium, strontium etc.) from low level radioactive effluents, alkali metal ion -H' exchanges on nine indigenous gel- and macroporous-type and nuclear grade resins have been studied at a total ionic strength of 0.1 mol dm .3 (in the case ofCs' -H' exchange it was 0.05 mol dm .3 ). The expected theoretical capacities were not attained by all the resins for the alkali metal ions. The water content (moles/equiv.) of the fully swollen resins for different alkali metal ionic forms do not follow the usual sequence of greater the tendency of the cation to hydrate the higher the water uptake, but a reverse trend. The ion exchange isotherms (plots of equivalent fractions of the ion in resin phase, N M1 to that in solution, N M ) were not satisfactory and sorption of cations, for most of the resins, was possible only when the acidity of the solution was lowered. The variations of the selectivity coefficient, K, with N M show that the resins are highly cross linked and the selectivity sequence: Cs + >K + >Na + >Li + , obtained for all the resins indicate that hydrated ions were involved in the exchange process. However, the increase in the selectivity was not accompanied by the release of water, but unusual uptake of water, during the exchange process. The characteristics of macroporous resins were not significantly different from those of the gel-type resins. The results are discussed in terms of heterogeneity in the polymer net work, improper sulphonation process resulting in the formation of functional groups at inaccessible sites with weak acidic character and the overall lack of control in the preparation of different resins. (author)
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Maximizing Ion Current by Space Charge Neutralization using Negative Ions and Dust Particles
International Nuclear Information System (INIS)
Smirnov, A.; Raitses, Y.; Fisch, N.J.
2005-01-01
Ion current extracted from an ion source (ion thruster) can be increased above the Child-Langmuir limit if the ion space charge is neutralized. Similarly, the limiting kinetic energy density of the plasma flow in a Hall thruster might be exceeded if additional mechanisms of space charge neutralization are introduced. Space charge neutralization with high-mass negative ions or negatively charged dust particles seems, in principle, promising for the development of a high current or high energy density source of positive light ions. Several space charge neutralization schemes that employ heavy negatively charged particles are considered. It is shown that the proposed neutralization schemes can lead, at best, only to a moderate but nonetheless possibly important increase of the ion current in the ion thruster and the thrust density in the Hall thruster
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Ion-selective electrode reviews
Thomas, J D R
1982-01-01
Ion-Selective Electrode Reviews, Volume 3, provides a review of articles on ion-selective electrodes (ISEs). The volume begins with an article on methods based on titration procedures for surfactant analysis, which have been developed for discrete batch operation and for continuous AutoAnalyser use. Separate chapters deal with detection limits of ion-selective electrodes; the possibility of using inorganic ion-exchange materials as ion-sensors; and the effect of solvent on potentials of cells with ion-selective electrodes. Also included is a chapter on advances in calibration procedures, the d
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An all permanent magnet electron cyclotron resonance ion source for heavy ion therapy.
Cao, Yun; Li, Jia Qing; Sun, Liang Ting; Zhang, Xue Zhen; Feng, Yu Cheng; Wang, Hui; Ma, Bao Hua; Li, Xi Xia
2014-02-01
A high charge state all permanent Electron Cyclotron Resonance ion source, Lanzhou All Permanent ECR ion source no. 3-LAPECR3, has been successfully built at IMP in 2012, which will serve as the ion injector of the Heavy Ion Medical Machine (HIMM) project. As a commercial device, LAPECR3 features a compact structure, small size, and low cost. According to HIMM scenario more than 100 eμA of C(5+) ion beam should be extracted from the ion source, and the beam emittance better than 75 π*mm*mrad. In recent commissioning, about 120 eμA of C(5+) ion beam was got when work gas was CH4 while about 262 eμA of C(5+) ion beam was obtained when work gas was C2H2 gas. The design and construction of the ion source and its low-energy transportation beam line, and the preliminary commissioning results will be presented in detail in this paper.
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Nonlinear dust-ion-acoustic waves in a multi-ion plasma with ...
Indian Academy of Sciences (India)
The basic features of such dust-ion-acoustic solitary and shock waves have been ... ion plasmas because of its vital role in understanding different types of ... cannot support the usual ion-acoustic waves, but can support the DIA waves of ...
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Low energy ion beam dynamics of NANOGAN ECR ion source
Energy Technology Data Exchange (ETDEWEB)
Kumar, Sarvesh, E-mail: sarvesh@iuac.res.in; Mandal, A.
2016-04-01
A new low energy ion beam facility (LEIBF) has been developed for providing the mass analyzed highly charged intense ion beams of energy ranging from a few tens of keV to a few MeV for atomic, molecular and materials sciences research. The new facility consists of an all permanent magnet 10 GHz electron cyclotron resonance (ECR) ion source (NANOGAN) installed on a high voltage platform (400 kV) which provides large currents of multiply charged ion beams. Higher emittance at low energy of intense ion beam puts a tremendous challenge to the beam optical design of this facility. The beam line consists of mainly the electrostatic quadrupoles, an accelerating section, analyzing cum switching magnet and suitable beam diagnostics including vacuum components. The accelerated ion beam is analyzed for a particular mass to charge (m/q) ratio as well as guided to three different lines along 75°, 90° and 105° using a large acceptance analyzing cum switching magnet. The details of transverse beam optics to all the beam lines with TRANSPORT and GICOSY beam optics codes are being described. Field computation code, OPERA 3D has been utilized to design the magnets and electrostatic quadrupoles. A theoretical estimation of emittance for optimized geometry of ion source is given so as to form the basis of beam optics calculations. The method of quadrupole scan of the beam is used to characterize the emittance of the final beam on the target. The measured beam emittance increases with m/q ratios of various ion beams similar to the trend observed theoretically.
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Radioactive ion beam production challenges at the Holifield Heavy Ion Research Facility
International Nuclear Information System (INIS)
Meigs, M.J.; Alton, G.D.; Dowling, D.T.; Haynes, D.L.; Jones, C.M.; Juras, R.C.; Lane, S.N.; Mills, G.D.; Mosko, S.W.; Olsen, D.K.; Tatum, B.A.
1992-01-01
The radioactive ion beam (RIB) project at the Holifield Heavy Ion Research Facility (HHIRF) will provide for reconfiguration of the HHIRF accelerator system to enable provision of low-intensity RIBs for nuclear and astrophysics research. As we have progressed with the design of the reconfiguration, we have encountered several challenges that were not immediately obvious when first contemplating the project. The challenges do not seem insurmountable but should keep life interesting for those of us doing the work. A brief review of the project will allow a better understanding of the challenges in RIB production. Radioactive ion beams will be produced with the Isotope Separator On-Line (ISOL) postacceleration technique. In particular, radioactive atoms will be produced by reactions in the thick stopping target of an ISOL-type target-ion source assembly using intense beams from the Oak Ridge Isochronous Cyclotron equipped with a light-ion internal source. This ISOL target-ion source assembly will be mounted on a high-voltage platform with a mass separator. The target ion source will operate at potentials up to 50 kV with respect to the high voltage platform. The radioactive atoms produced by nuclear reactions in the target diffuse to the surface of the heated target material, desorb from this surface, and effuse through a heated transfer tube into an ion source where ionization and extraction take place. Two types of ion sources will be initially considered. A Forced Electron Beam Induced Arc Discharge source, similar to those used by the ISOLDE facility at CERN and by the UNISOR facility at ORNL, will be built to produce positive ions. These positive ions will be focused through an alkali vapor charge-exchange canal to produce negative ions for tandem injection. In addition, a direct negative surface ionization addition or modification to the above source will be built and investigated
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Improvement of highly charged ion production in the ECR source of heavy ions
International Nuclear Information System (INIS)
Shirkov, G.D.
1996-01-01
Some physical limitations of the highly charged ion production in the ECR source are analyzed in this report. A few possible ways to improve the output of highly charged ions from the ECR source for heavy ions are proposed. A new library of computer codes for the numerical simulation of heavy ion production in the ECR ion source is used to examine these ways to improve the ECR source operation according to the CERN program of heavy ion acceleration. copyright 1996 American Institute of Physics
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Plasma focus as an heavy ion source in the problem of heavy ion fusion
International Nuclear Information System (INIS)
Gribkov, V.A.; Dubrovskij, A.V.; Kalachev, N.V.; Krokhin, O.N.; Silin, P.V.; Nikulin, V.Ya.; Cheblukov, Yu.N.
1984-01-01
Results of experiments on the ion flux formation in a plasma focus (PF) to develop a multicharged ion source for thermonuclear facility driver are presented. In plasma focus accelerating section copper ions were injected. Advantages of the suggested method of ion beam formation are demonstrated. Beam emittance equalling < 0.1 cmxmrad is obtained. Plasma focus ion energy exceeds 1 MeV. Plasma focus in combination with a neodymium laser is thought to be a perspective ion source for heavy ion fusion
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Directory of Open Access Journals (Sweden)
Francisco Ramallo
2016-08-01
Full Text Available Nuestra investigación se propone desestabilizar el relato oficial que la historiografía de la educación reprodujo y consolidó del bachillerato argentino (y con él el de la enseñanza secundaria a través de los “lugares comunes”, prejuicios analíticos, lecturas “a priori” y miradas “desde arriba” que caracterizaron a los relatos sobre los colegios nacionales. Todo ello a partir del análisis de caso de un colegio nacional: el de Mar del Plata. Específicamente en este artículo pretendemos identificar a los estudiantes de los colegios nacionales en la primera mitad del siglo XX. Para ello en la primera parte recuperamos los estudios realizados al respecto e indagamos las interpretaciones historiográficas que los respaldan; y en la segunda parte nos concentramos en un estudio empírico de los alumnos de este colegio. Nuestro argumento es que si bien los colegios se caracterizaron por representar una enseñanza “tradicional”, “selectiva” y “elitista”, en la práctica actuaron como espacios abiertos y permeables al cual accedieron estudiantes de diferentes lugares en la escala social (o al menos de sectores sociales más amplios que los reconocidos por los discursos de la época y por los relatos al respecto. De este modo remarcamos que el bachillerato marplantense fue conformado por actores poco considerados por la historiografía de la educación: las mujeres (que representaron un tercio del alumnado y los gringos e hijos de inmigrantes (cuya cifra superó las dos terceras partes de los jóvenes.
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Directory of Open Access Journals (Sweden)
Héctor Luis Adriani
2005-01-01
Full Text Available The aim of this paper is to identify of the main features and trends of precarious work in Great La Plata, considering the current national economic dynamics. Taking as benchmark the "full" employment, different degress of precariousness can be found according to the lack of features that characterize said fullness. Thus, there would be a gradation of situations, from a maximum reference in the "full" employment to a minimum one in the absolute unemployment. The analysis is based on the information provide by a survey called Encuesta Permanente de Hogares (EPH, which comprises the time between the second semester in 2003 and the first one in 2004, since after their restructuring EPH only provides information on that period so far. The results show that in the region, precarious jobs amount to 39.3 of the economically active population in the first semester in 2004. If the unemployed are included, over 50 of the population undergo employment problems and there exists pressure of the demanding underemployed sector on the labor market. In the public sector, 16.4 of the people employed are precarized, and the percentage rises to 34 if the beneficiaries of unemployment programs are included. In the private sector, precarious employment reaches 54. Regarding the evolution of per capita income, the levels reached are below those earned before the 2002 devaluation, even within the groups of employed people whose purchasing power improved between 2003 and 2004. The main contributions of this paper lie in the identification, quantification and characterization of precarious employment in the region in the post-devaluation period through the analysis of the EPH Data Base.
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Scheers, Johan; Niedzicki, Leszek; Zukowska, Grażyna Z; Johansson, Patrik; Wieczorek, Władysław; Jacobsson, Per
2011-06-21
Molecular level interactions are of crucial importance for the transport properties and overall performance of ion conducting electrolytes. In this work we explore ion-ion and ion-solvent interactions in liquid and solid polymer electrolytes of lithium 4,5-dicyano-(2-trifluoromethyl)imidazolide (LiTDI)-a promising salt for lithium battery applications-using Raman spectroscopy and density functional theory calculations. High concentrations of ion associates are found in LiTDI:acetonitrile electrolytes, the vibrational signatures of which are transferable to PEO-based LiTDI electrolytes. The origins of the spectroscopic changes are interpreted by comparing experimental spectra with simulated Raman spectra of model structures. Simple ion pair models in vacuum identify the imidazole nitrogen atom of the TDI anion to be the most important coordination site for Li(+), however, including implicit or explicit solvent effects lead to qualitative changes in the coordination geometry and improved correlation of experimental and simulated Raman spectra. To model larger aggregates, solvent effects are found to be crucial, and we finally suggest possible triplet and dimer ionic structures in the investigated electrolytes. In addition, the effects of introducing water into the electrolytes-via a hydrate form of LiTDI-are discussed.
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Experiments on secondary ion emission with multicharged keV ion bombardement
International Nuclear Information System (INIS)
Della Negra, S.; Depauw, J.; Joret, H.; Le Beyec, Y.; Schweikert, E.A.
1987-01-01
An electron cyclotron resonance ion source was used to study the influence of the incident charge state of keV ions on secondary ion emission. The experiments were run with 18 keV Arn+ (1 < n < 11) beams produced by a minimafios source. Various types of targets were bombarded by the ion beam and the sputtered ionized species were identified by time of flight mass spectrometry. The experimental arrangement is detailed and preliminary results are indicated
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A heating mechanism of ions due to large amplitude coherent ion acoustic wave
International Nuclear Information System (INIS)
Yajima, Nobuo; Kawai, Yoshinobu; Kogiso, Ken.
1978-05-01
Ion heating mechanism in a plasma with a coherent ion acoustic wave is studied experimentally and numerically. Ions are accelerated periodically in the electrostatic potential of the coherent wave and their oscillation energy is converted into the thermal energy of ions through the collision with the neutral atoms in plasma. The Monte Carlo calculation is applied to obtain the ion temperature. The amplitude of the electrostatic potential, the mean number of collisions and the mean life time of ions are treated as parameters in the calculation. The numerical results are compared with the experiments and both of them agree well. It is found that the ion temperature increases as the amplitude of the coherent wave increases and the high energy tail in the distribution function of ions are observed for the case of large wave-amplitude. (author)
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Molecular and negative ion production by a standard electron cyclotron resonance ion source
Energy Technology Data Exchange (ETDEWEB)
Racz, R. [Institute of Nuclear Research (ATOMKI), Bem ter 18/c, H-4026 Debrecen (Hungary); University of Debrecen, Egyetem ter 1, H-4010 Debrecen (Hungary); Biri, S.; Juhasz, Z.; Sulik, B. [Institute of Nuclear Research (ATOMKI), Bem ter 18/c, H-4026 Debrecen (Hungary); Palinkas, J. [University of Debrecen, Egyetem ter 1, H-4010 Debrecen (Hungary)
2012-02-15
Molecular and negative ion beams, usually produced in special ion sources, play an increasingly important role in fundamental and applied atomic physics. The ATOMKI-ECRIS is a standard ECR ion source, designed to provide highly charged ion (HCI) plasmas and beams. In the present work, H{sup -}, O{sup -}, OH{sup -}, O{sub 2}{sup -}, C{sup -}, C{sub 60}{sup -} negative ions and H{sub 2}{sup +}, H{sub 3}{sup +}, OH{sup +}, H{sub 2}O{sup +}, H{sub 3}O{sup +}, O{sub 2}{sup +} positive molecular ions were generated in this HCI-ECRIS. Without any major modification in the source and without any commonly applied tricks (such as usage of cesium or magnetic filter), negative ion beams of several {mu}A and positive molecular ion beams in the mA range were successfully obtained.
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Shoji, Masafumi; Miyoshi, Yoshizumi; Katoh, Yuto; Keika, Kunihiro; Angelopoulos, Vassilis; Kasahara, Satoshi; Asamura, Kazushi; Nakamura, Satoko; Omura, Yoshiharu
2017-09-01
Electromagnetic plasma waves are thought to be responsible for energy exchange between charged particles in space plasmas. Such an energy exchange process is evidenced by phase space holes identified in the ion distribution function and measurements of the dot product of the plasma wave electric field and the ion velocity. We develop a method to identify ion hole formation, taking into consideration the phase differences between the gyromotion of ions and the electromagnetic ion cyclotron (EMIC) waves. Using this method, we identify ion holes in the distribution function and the resulting nonlinear EMIC wave evolution from Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations. These ion holes are key to wave growth and frequency drift by the ion currents through nonlinear wave-particle interactions, which are identified by a computer simulation in this study.
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Ion Dynamics at Shocks: Ion Reflection and Beam Formation at Quasi-perpendicular Shocks
International Nuclear Information System (INIS)
Kucharek, Harald; Moebius, Eberhard
2005-01-01
The physics of collisionless shocks is controlled by the ion dynamics. The generation of gyrating ions by reflection as well as the formation of field-aligned ion beams are essential parts of this dynamic. On the one hand reflection is most likely the first interaction of ions with the shock before they undergo the downstream thermalization process. On the other hand field-aligned ion beams, predominately found at the quasi-perpendicular bow shock, propagate into the distant foreshock region and may create wave activity. We revisit ion reflection, the source and basic production mechanism of field-aligned ion beams, by using multi-spacecraft measurements and contrast these observations with existing theories. Finally, we propose an alternative production mechanism
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Generation and focusing of intense ion beams with an inverse pinch ion diode
International Nuclear Information System (INIS)
Hashimoto, Yoshiyuki; Sato, Morihiko; Yatsuzuka, Mitsuyasu; Nobuhara, Sadao
1992-01-01
Generation and focusing of ion beams using an inverse pinch ion diode with a flat anode has been studied. The ion beams generated with the inverse pinch ion diode were found to be focused at 120 mm from the anode by the electrostatic field in the diode. The energy and maximum current density of the ion beams were 180 keV and 420 A/cm 2 , respectively. The focusing angle of the ion beams was 4.3deg. The beam brightness was estimated to be 1.3 GW/cm 2 ·rad 2 . The focusing distance of the ion beams was found to be controllable by changing the diameters of the anode and cathode. (author)
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Behaviour of tetraalkylammonium ions in high-field asymmetric waveform ion mobility spectrometry.
Aksenov, Alexander A; Kapron, James T
2010-05-30
High-field asymmetric waveform ion mobility spectrometry (FAIMS) is an ion-filtering technique recently adapted for use with liquid chromatography/mass spectrometry (LC/MS) to remove interferences during analysis of complex matrices. This is the first systematic study of a series of singly charged tetraalkylammonium ions by FAIMS-MS. The compensation voltage (CV) is the DC offset of the waveform which permits the ion to emerge from FAIMS and it was determined for each member of the series under various conditions. The electrospray ionization conditions explored included spray voltage, vaporizer temperature, and sheath and auxiliary gas pressure. The FAIMS conditions explored included carrier gas flow rate, electrode temperature and composition of the carrier gas. Optimum desolvation was achieved using sufficient carrier gas (flow rate > or = 2 L/min) to ensure stable response. Low-mass ions (m/z 100-200) are more susceptible to changes in electrode temperature and gas composition than high mass ions (m/z 200-700). As a result of this study, ions are reliably analyzed using standard FAIMS conditions (dispersion voltage -5000 V, carrier gas flow rate 3 L/min, 50% helium/50%nitrogen, inner electrode temperature 70 degrees C and outer electrode temperature 90 degrees C). Variation of FAIMS conditions may be of great use for the separation of very low mass tetraalkylammonium (TAA) ions from other TAA ions. The FAIMS conditions do not appear to have a major effect on higher mass ions. Copyright 2010 John Wiley & Sons, Ltd.
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Specific ion effects on membrane potential and the permselectivity of ion exchange membranes
Geise, Geoffrey M.
2014-08-26
© the Partner Organisations 2014. Membrane potential and permselectivity are critical parameters for a variety of electrochemically-driven separation and energy technologies. An electric potential is developed when a membrane separates electrolyte solutions of different concentrations, and a permselective membrane allows specific species to be transported while restricting the passage of other species. Ion exchange membranes are commonly used in applications that require advanced ionic electrolytes and span technologies such as alkaline batteries to ammonium bicarbonate reverse electrodialysis, but membranes are often only characterized in sodium chloride solutions. Our goal in this work was to better understand membrane behaviour in aqueous ammonium bicarbonate, which is of interest for closed-loop energy generation processes. Here we characterized the permselectivity of four commercial ion exchange membranes in aqueous solutions of sodium chloride, ammonium chloride, sodium bicarbonate, and ammonium bicarbonate. This stepwise approach, using four different ions in aqueous solution, was used to better understand how these specific ions affect ion transport in ion exchange membranes. Characterization of cation and anion exchange membrane permselectivity, using these ions, is discussed from the perspective of the difference in the physical chemistry of the hydrated ions, along with an accompanying re-derivation and examination of the basic equations that describe membrane potential. In general, permselectivity was highest in sodium chloride and lowest in ammonium bicarbonate solutions, and the nature of both the counter- and co-ions appeared to influence measured permselectivity. The counter-ion type influences the binding affinity between counter-ions and polymer fixed charge groups, and higher binding affinity between fixed charge sites and counter-ions within the membrane decreases the effective membrane charge density. As a result permselectivity decreases. The
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Observations of strong ion-ion correlations in dense plasmas
Energy Technology Data Exchange (ETDEWEB)
Ma, T.; Fletcher, L.; Pak, A.; Chapman, D. A.; Falcone, R. W.; Fortmann, C.; Galtier, E.; Gericke, D. O.; Gregori, G.; Hastings, J.; Landen, O. L.; Le Pape, S.; Lee, H. J.; Nagler, B.; Neumayer, P.; Turnbull, D.; Vorberger, J.; White, T. G.; Wünsch, K.; Zastrau, U.; Glenzer, S. H.; Döppner, T.
2014-05-01
Using simultaneous spectrally, angularly, and temporally resolved x-ray scattering, we measure the pronounced ion-ion correlation peak in a strongly coupled plasma. Laser-driven shock-compressed aluminum at ~3× solid density is probed with high-energy photons at 17.9 keV created by molybdenum He-α emission in a laser-driven plasma source. The measured elastic scattering feature shows a well-pronounced correlation peak at a wave vector of k=4k=4Å-1. The magnitude of this correlation peak cannot be described by standard plasma theories employing a linear screened Coulomb potential. Advanced models, including a strong short-range repulsion due to the inner structure of the aluminum ions are however in good agreement with the scattering data. These studies have demonstrated a new highly accurate diagnostic technique to directly measure the state of compression and the ion-ion correlations. We have since applied this new method in single-shot wave-number resolved S(k) measurements to characterize the physical properties of dense plasmas.
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New experimental initiatives using very highly charged ions from an 'electron beam ion trap'
International Nuclear Information System (INIS)
Schneider, D.
1996-01-01
A short review of the experimental program in highly-charged heavy ion physics conducted at the Lawrence Livermore National Laboratory Electron Beam Ion Trap (EBIT) facility is presented. The heavy-ion research, involving ions up to fully stripped U 92+ , includes precision x-ray spectroscopy and lifetime studies, electron impact ionization and excitation cross section measurements. The investigations of ion-surface interactions following the impact of high-Z highly charged ions on surfaces are aimed to study the neutralization dynamics effecting the ion and the response of the surface as well. (author)
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Development of exploding wire ion source for intense pulsed heavy ion beam accelerator
International Nuclear Information System (INIS)
Ochiai, Y.; Murata, T.; Ito, H.; Masugata, K.
2012-01-01
A Novel exploding wire type ion source device is proposed as a metallic ion source of intense pulsed heavy ion beam (PHIB) accelerator. In the device multiple shot operations is realized without breaking the vacuum. The basic characteristics of the device are evaluated experimentally with an aluminum wire of diameter 0.2 mm, length 25 mm. Capacitor bank of capacitance 3 μF, charging voltage 30 kV was used and the wire was successfully exploded by a discharge current of 15 kA, rise time 5.3 μs. Plasma flux of ion current density around 70 A/cm 2 was obtained at 150 mm downstream from the device. The drift velocity of ions evaluated by a time-of-flight method was 2.7x10 4 m/sec, which corresponds to the kinetic energy of 100 eV for aluminum ions. From the measurement of ion current density distribution ion flow is found to be concentrated to the direction where ion acceleration gap is placed. From the experiment the device is found to be acceptable for applying PHIB accelerator. (author)
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An all permanent magnet electron cyclotron resonance ion source for heavy ion therapy
Energy Technology Data Exchange (ETDEWEB)
Cao, Yun, E-mail: caoyun@impcas.ac.cn; Li, Jia Qing; Sun, Liang Ting; Zhang, Xue Zhen; Feng, Yu Cheng; Wang, Hui; Ma, Bao Hua; Li, Xi Xia [Institute of Modern Physics, CAS, Lanzhou 730000 (China)
2014-02-15
A high charge state all permanent Electron Cyclotron Resonance ion source, Lanzhou All Permanent ECR ion source no. 3-LAPECR3, has been successfully built at IMP in 2012, which will serve as the ion injector of the Heavy Ion Medical Machine (HIMM) project. As a commercial device, LAPECR3 features a compact structure, small size, and low cost. According to HIMM scenario more than 100 eμA of C{sup 5+} ion beam should be extracted from the ion source, and the beam emittance better than 75 π*mm*mrad. In recent commissioning, about 120 eμA of C{sup 5+} ion beam was got when work gas was CH{sub 4} while about 262 eμA of C{sup 5+} ion beam was obtained when work gas was C{sub 2}H{sub 2} gas. The design and construction of the ion source and its low-energy transportation beam line, and the preliminary commissioning results will be presented in detail in this paper.
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Recent advances in high current vacuum arc ion sources for heavy ion fusion
Qi Nian Sheng; Prasad, R R; Krishnan, M S; Anders, A; Kwan, J; Brown, I
2001-01-01
For a heavy ion fusion induction linac driver, a source of heavy ions with charge states 1+-3+, approx 0.5 A current beams, approx 20 mu s pulse widths and approx 10 Hz repetition rates is required. Thermionic sources have been the workhorse for the Heavy Ion Fusion (HIF) program to date, but suffer from heating problems for large areas and contamination. They are limited to low (contact) ionization potential elements and offer relatively low ion fluxes with a charge state limited to 1+. Gas injection sources suffer from partial ionization and deleterious neutral gas effects. The above shortcomings of the thermionic ion sources can be overcome by a vacuum arc ion source. The vacuum arc ion source is a good candidate for HIF applications. It is capable of providing ions of various elements and different charge states in short and long pulse bursts and high beam current density. Under a Phase-I STTR from DOE, the feasibility of the vacuum arc ion source for the HIF applications was investigated. We have modifie...
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Anomalous surface behavior of hydrated guanidinium ions due to ion pairing
Ekholm, Victor; Vazdar, Mario; Mason, Philip E.; Bialik, Erik; Walz, Marie-Madeleine; Öhrwall, Gunnar; Werner, Josephina; Rubensson, Jan-Erik; Jungwirth, Pavel; Björneholm, Olle
2018-04-01
Surface affinity of aqueous guanidinium chloride (GdmCl) is compared to that of aqueous tetrapropylammonium chloride (TPACl) upon addition of sodium chloride (NaCl) or disodium sulfate (Na2SO4). The experimental results have been acquired using the surface sensitive technique X-ray photoelectron spectroscopy on a liquid jet. Molecular dynamics simulations have been used to produce radial distribution functions and surface density plots. The surface affinities of both TPA+ and Gdm+ increase upon adding NaCl to the solution. With the addition of Na2SO4, the surface affinity of TPA+ increases, while that of Gdm+ decreases. From the results of MD simulations it is seen that Gdm+ and SO4 2 - ions form pairs. This finding can be used to explain the decreased surface affinity of Gdm+ when co-dissolved with SO4 2 - ions. Since SO4 2 - ions avoid the surface due to the double charge and strong water interaction, the Gdm+-SO4 2 - ion pair resides deeper in the solutions' bulk than the Gdm+ ions. Since TPA+ does not form ion pairs with SO4 2 -, the TPA+ ions are instead enriched at the surface.
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Energy landscapes for mobile ions in ion conducting solids
Indian Academy of Sciences (India)
molecular dynamics (MD) simulations yields quantitative predictions of the ion transport characteristics. As ... Solid electrolytes; bond valence analysis; ion transport in glasses. 1. .... clusters are considered to contribute only to a.c. conduc-.
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DETERMINATION OF STRONTIUM IONS IN WATERS WITH A HIGH CONTENT OF SODIUM IONS
Directory of Open Access Journals (Sweden)
Tatiana Mitina
2015-06-01
Full Text Available This paper reports on the influence of sodium ions on experimental determination of strontium ions concentration in waters with a high content of sodium ions by using emission flame photometry and atomic absorption spectroscopy. For the method of emission flame photometry it was shown that at a wavelength of 460.7 nm (spectral emission line of strontium the emission is linearly dependent on the concentration of sodium ions. The greatest impact of high concentrations of sodium ions on the result of determination the strontium ions concentration has been registered at low levels of strontium. The influence of nitric acid on the results is also discussed. In the case of using atomic absorption spectroscopy method no influence of sodium ions and nitric acid on the results of determination the strontium ions concentration was revealed. The metrological characteristics of both methods are evaluated.
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An ion beam deceleration lens for ultra-low-energy ion bombardment of naked DNA
Energy Technology Data Exchange (ETDEWEB)
Thopan, P.; Prakrajang, K. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongkumkoon, P. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Suwannakachorn, D. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuldyuld@gmail.com [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)
2013-07-15
Highlights: ► An ion beam deceleration lens was designed and constructed. ► The deceleration lens was installed and tested. ► The decelerated ion beam energy was measured using an electrical field. ► Decelerated ultra-low-energy ion beam bombarded naked DNA. ► Ion beam with energy of a few tens of eV could break DNA strands. -- Abstract: Study of low-energy ion bombardment effect on biological living materials is of significance. High-energy ion beam irradiation of biological materials such as organs and cells has no doubt biological effects. However, ion energy deposition in the ion-bombarded materials dominantly occurs in the low-energy range. To investigate effects from very-low-energy ion bombardment on biological materials, an ion beam deceleration lens is necessary for uniform ion energy lower than keV. A deceleration lens was designed and constructed based on study of the beam optics using the SIMION program. The lens consisted of six electrodes, able to focus and decelerate primary ion beam, with the last one being a long tube to obtain a parallel uniform exiting beam. The deceleration lens was installed to our 30-kV bioengineering-specialized ion beam line. The final decelerated-ion energy was measured using a simple electrostatic field to bend the beam to range from 10 eV to 1 keV controlled by the lens parameters and the primary beam condition. In a preliminary test, nitrogen ion beam at 60 eV decelerated from a primary 20-keV beam bombarded naked plasmid DNA. The original DNA supercoiled form was found to change to relaxed and linear forms, indicating single or double strand breaks. The study demonstrated that the ion bombardment with energy as low as several-tens eV was possible to break DNA strands and thus potential to cause genetic modification of biological cells.
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An ion beam deceleration lens for ultra-low-energy ion bombardment of naked DNA
International Nuclear Information System (INIS)
Thopan, P.; Prakrajang, K.; Thongkumkoon, P.; Suwannakachorn, D.; Yu, L.D.
2013-01-01
Highlights: ► An ion beam deceleration lens was designed and constructed. ► The deceleration lens was installed and tested. ► The decelerated ion beam energy was measured using an electrical field. ► Decelerated ultra-low-energy ion beam bombarded naked DNA. ► Ion beam with energy of a few tens of eV could break DNA strands. -- Abstract: Study of low-energy ion bombardment effect on biological living materials is of significance. High-energy ion beam irradiation of biological materials such as organs and cells has no doubt biological effects. However, ion energy deposition in the ion-bombarded materials dominantly occurs in the low-energy range. To investigate effects from very-low-energy ion bombardment on biological materials, an ion beam deceleration lens is necessary for uniform ion energy lower than keV. A deceleration lens was designed and constructed based on study of the beam optics using the SIMION program. The lens consisted of six electrodes, able to focus and decelerate primary ion beam, with the last one being a long tube to obtain a parallel uniform exiting beam. The deceleration lens was installed to our 30-kV bioengineering-specialized ion beam line. The final decelerated-ion energy was measured using a simple electrostatic field to bend the beam to range from 10 eV to 1 keV controlled by the lens parameters and the primary beam condition. In a preliminary test, nitrogen ion beam at 60 eV decelerated from a primary 20-keV beam bombarded naked plasmid DNA. The original DNA supercoiled form was found to change to relaxed and linear forms, indicating single or double strand breaks. The study demonstrated that the ion bombardment with energy as low as several-tens eV was possible to break DNA strands and thus potential to cause genetic modification of biological cells
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Pulsed, Inductively Generated, Streaming Plasma Ion Source for Heavy Ion Fusion Linacs
International Nuclear Information System (INIS)
Steven C. Glidden; Howard D Sanders; John B. Greenly; Daniel L. Dongwoo
2006-01-01
This report describes a compact, high current density, pulsed ion source, based on electrodeless, inductively driven gas breakdown, developed to meet the requirements on normalized emittance, current density, uniformity and pulse duration for an ion injector in a heavy-ion fusion driver. The plasma source produces >10 (micro)s pulse of Argon plasma with ion current densities >100 mA/cm2 at 30 cm from the source and with strongly axially directed ion energy of about 80 eV, and sub-eV transverse temperature. The source has good reproducibility and spatial uniformity. Control of the current density during the pulse has been demonstrated with a novel modulator coil method which allows attenuation of the ion current density without significantly affecting the beam quality. This project was carried out in two phases. Phase 1 used source configurations adapted from light ion sources to demonstrate the feasibility of the concept. In Phase 2 the performance of the source was enhanced and quantified in greater detail, a modulator for controlling the pulse shape was developed, and experiments were conducted with the ions accelerated to >40 kV
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Ion-selective electrode reviews
Thomas, J D R
1985-01-01
Ion-Selective Electrode Reviews, Volume 7 is a collection of papers that covers the applications of electrochemical sensors, along with the versatility of ion-selective electrodes. The coverage of the text includes solid contact in membrane ion-selective electrodes; immobilized enzyme probes for determining inhibitors; potentiometric titrations based on ion-pair formation; and application of ion-selective electrodes in soil science, kinetics, and kinetic analysis. The text will be of great use to chemists and chemical engineers.
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Directory of Open Access Journals (Sweden)
Nicolás Mato
2013-12-01
Fükelman, Cristina. La cultura visual en el Río de la Plata, 1834-1852: innovaciones a partir de la configuración y de la función de la imagen política y costumbrista, La Plata, Archivo Histórico de la Provincia de Buenos Aires, 2013, 138 p. por Emir Reitano
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Observation of ion-acoustic rarefaction solitons in a multicomponent plasma with negative ions
International Nuclear Information System (INIS)
Ludwig, G.O.; Ferreira, J.L.; Nakamura, Y.
1984-01-01
The propagation of ion-acoustic solitons in a plasma with negative ions has been observed. For sufficiently large concentration of negative ions, applied rarefactive (negative) voltage pulses break up into solitons, whereas compressive pulses evolve into wave trains, with exactly the opposite behavior as that for a plasma composed only of positive ions. There is a critical value of the negative-ion concentration for which a finite-amplitude pulse propagates without steepening
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High charge state metal ion production in vacuum arc ion sources
International Nuclear Information System (INIS)
Brown, I.G.; Anders, A.; Anders, S.
1994-01-01
The vacuum arc is a rich source of highly ionized metal plasma that can be used to make a high current metal ion source. Vacuum arc ion sources have been developed for a range of applications including ion implantation for materials surface modification, particle accelerator injection for fundamental nuclear physics research, and other fundamental and applied purposes. Typically the source is repetitively pulsed with pulse length of order a millisecond and duty cycle or order 1% and operation of a dc embodiment has been demonstrated also. Beams have been produced from over 50 of the solid metals of the periodic table, with mean ion energy up to several hundred keV and with peak (pulsed) beam current up to several amperes. The ion charge state distribution has been extensively studied. Ion spectra have been measured for a wide range of metallic cathode materials, including Li, C, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Sr, Y, Zr, Nb, Mo, Pd, Ag, Cd, In, Sn, Sb, Ba, La, Ce, Pr, Nd, Sm, Gd, Dy, Ho, Er, Tm, Yb, Hf, Ta, W, Ir, Pt, Au, Pb, Bi, Th and U, as well as compound and alloy cathode materials such as TiC, SiC, UC, PbS, brass, and stainless steel. The ions generated are in general multiply-stripped with a mean charge state of from 1 to 3, depending on the particular metal species, and the charge state distribution can have components from Q = 1+ to 6+. Here the authors review the characteristics of vacuum arc ion sources from the perspective of their high charge state metal ion production
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International Nuclear Information System (INIS)
Bazin, V.; Boduch, P.; Chesnel, J.Y.; Fremont, F.; Lecler, D.; Pacquet, J. Y.; Gaubert, G.; Leroy, R.
1999-01-01
Modifications in the ECR 4M ion source are described, which conducted to realization of the advanced source 'SUPERSHYPIE'. The Ar 8+ ion collision with Cs(6s,6p) were studied by photon spectroscopy at low energy, where the process is dominated by simple electron capture. Results obtained with 'SUPERSHYPIE' source are presented. The source was utilized also in ion-molecule collisions (CO, H 2 ) to study the spectra of recoil ions and Auger electron spectra in the Ar 17+ He collisions. The excellent performances of 'SUPERSHYPIE' in high charge production and concerning its accurate and fine control and stability are illustrated and underlined as compared with those of ECR 4M source
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Sharma, S D; Gupta, R
2000-02-01
The chromatographic behavior of 40 metal ions is studied on titanium (IV) arsenate, titanium (IV) phosphate-, titanium (IV) molybdate-, titanium(IV) tungstate-, and titanium(IV) selenite-impregnated papers in 0.1M oxalic, citric, and tartaric acid as mobile phases. Similar studies are carried out on Whatman No. 1 papers for comparison. The ion-exchange capacity of these papers is determined, and their selectivity for different cations is discussed. The mechanism of migration is explained in terms of ion-exchange, precipitation, and adsorption. The prediction of elution sequence from RF values is also checked. The average Ri is found to be almost linearly dependent on the charge of the metal ions. The effect of the pKa of complexing acids on average RF values of 3d series metal ions is explained. A number of binary and ternary separations are achieved.
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Ion beam stabilization in ion implantation equipment
International Nuclear Information System (INIS)
Pina, L.
1973-01-01
The results are presented of experimental efforts aimed at ion beam current stabilization in an equipment for ion implantation in solids. The related problems of power supplies are discussed. Measured characteristics of laboratory equipment served the determination of the parameters to be required of the supplies as well as the design and the construction of the supplies. The respective wiring diagram is presented. (J.K.)
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Structure of ion-implanted ceramics
International Nuclear Information System (INIS)
Naramoto, Hiroshi
1983-01-01
The variation of structure of LiF, MgO, Al 2 O 3 and TiO 2 accompanying annealing after ion implantation is explained. The analysis of structure is usually made by the perturbed gamma ray angular correlation, the internal electron Moessbauer method, or the ion scattering method. The results of analyses are discussed for alkali ion implantation, Fe-ion implantation, In-ion implantation, Au-ion implantation, Pt-ion implantation, Pb-ion implantation and transition metal ion implantation. The coupling of the implanted elements with lattice defects and matrix elements, and the compatibility between deposited elements and matrix crystal lattice were studied. The variation of physical properties due to ion implantation such as phase transition, volume change, the control of single crystal region, and the variation of hardness near surface were investigated, and the examples are presented. (Kato, T.)
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Energy Technology Data Exchange (ETDEWEB)
Pikin, A.; Alessi, J.; Beebe, E.; Kponou, A.; Okamura, M.; Raparia, D.; Ritter, J.; Tan, Y.; Kuznetsov, G.
2011-09-10
RHIC EBIS has been commissioned to operate as a versatile ion source on RHIC injection facility supplying ion species from He to Au for Booster. Except for light gaseous elements RHIC EBIS employs ion injection from several external primary ion sources. With electrostatic optics fast switching from one ion species to another can be done on a pulse to pulse mode. The design of an ion optical structure and the results of simulations for different ion species are presented. In the choice of optical elements special attention was paid to spherical aberrations for high-current space charge dominated ion beams. The combination of a gridded lens and a magnet lens in LEBT provides flexibility of optical control for a wide range of ion species to satisfy acceptance parameters of RFQ. The results of ion transmission measurements are presented.
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Ion beam analysis of metal ion implanted surfaces
Energy Technology Data Exchange (ETDEWEB)
Evans, P.J.; Chu, J.W.; Johnson, E.P.; Noorman, J.T. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Sood, D.K. [Royal Melbourne Inst. of Tech., VIC (Australia)
1993-12-31
Ion implantation is an established method for altering the surface properties of many materials. While a variety of analytical techniques are available for the characterisation of implanted surfaces, those based on particle accelerators such as Rutherford backscattering (RBS) and nuclear reaction analysis (NRA) provide some of the most useful and powerful for this purpose. Application of the latter techniques to metal ion implantation research at ANSTO will be described with particular reference to specific examples from recent studies. Where possible, the information obtained from ion beam analysis will be compared with that derived from other techniques such as Energy Dispersive X-ray (EDX) and Auger spectroscopies. 4 refs., 5 figs.
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Ion beam analysis of metal ion implanted surfaces
Energy Technology Data Exchange (ETDEWEB)
Evans, P J; Chu, J W; Johnson, E P; Noorman, J T [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Sood, D K [Royal Melbourne Inst. of Tech., VIC (Australia)
1994-12-31
Ion implantation is an established method for altering the surface properties of many materials. While a variety of analytical techniques are available for the characterisation of implanted surfaces, those based on particle accelerators such as Rutherford backscattering (RBS) and nuclear reaction analysis (NRA) provide some of the most useful and powerful for this purpose. Application of the latter techniques to metal ion implantation research at ANSTO will be described with particular reference to specific examples from recent studies. Where possible, the information obtained from ion beam analysis will be compared with that derived from other techniques such as Energy Dispersive X-ray (EDX) and Auger spectroscopies. 4 refs., 5 figs.
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Ion beam analysis of metal ion implanted surfaces
International Nuclear Information System (INIS)
Evans, P.J.; Chu, J.W.; Johnson, E.P.; Noorman, J.T.; Sood, D.K.
1993-01-01
Ion implantation is an established method for altering the surface properties of many materials. While a variety of analytical techniques are available for the characterisation of implanted surfaces, those based on particle accelerators such as Rutherford backscattering (RBS) and nuclear reaction analysis (NRA) provide some of the most useful and powerful for this purpose. Application of the latter techniques to metal ion implantation research at ANSTO will be described with particular reference to specific examples from recent studies. Where possible, the information obtained from ion beam analysis will be compared with that derived from other techniques such as Energy Dispersive X-ray (EDX) and Auger spectroscopies. 4 refs., 5 figs
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Directory of Open Access Journals (Sweden)
Luz Fernanda Sua
2014-10-01
Full Text Available Introducción: La determinación del oncogén HER2 es crítica en las pacientes que responderán al anticuerpo monoclonal humanizado Trastuzumab. La técnica de hibridación in situ cromogénica y con plata (Dual ISH ha sido exitosamente probada en la detección de la amplificación del gen HER2, un importante biomarcador del cáncer de mama que combina las ventajas de la automatización y la microscopía de luz, mejorando el flujo de trabajo en el laboratorio. Objetivos: verificar si la metodología automatizada de hibridización in situ cromogénica y con plata (Dual ISH realizada en el equipo Benchmark XT de Ventana Medical Systems® puede ser comparable con la hibridización in situ fluorescente (FISH en casos de la Fundación Valle del Lili. Metodología: Previa aprobación del Comité de Ética de la Fundación Valle del Lili, evaluamos un total de 42 casos, encontrando 98.1% con un nivel de concordancia total, tanto de la hibridización in situ fluorescente (FISH y de la inmunohistoquímica (IHQ con el ISH Dual. Determinamos un nivel de concordancia del 94.4% en el estudio del nivel de amplificación del gen HER2 por FISH y por ISH Dual. La concordancia entre la determinación de la expresión de la proteína HER2 por IHQ y por ISH Dual fue del 100%. Al evaluar nuestro coeficiente Kappa este fue de 0.97 y nuestro coeficiente de correlación intraclases en referencia con el FISH fue casi perfecto 0.85. Conclusión: nosotros observamos una reducción del tiempo de procesamiento con la técnica Dual ISH al ser una metodología automatizada (Equipo BenchMark XT de Ventana® cuando la comparamos con el protocolo FISH. La técnica Dual ISH permite la evaluación morfológica y estudia simultáneamente el centrómero del cromosoma 17 y el oncogén HER2. Esta metodología se estudia en el microscopio de luz (60x, es cuantitativa, se puede archivar y se encuentra aprobada por la Administración de Drogas y Alimentos de los Estados Unidos (FDA.
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International Nuclear Information System (INIS)
Brown, I.G.
1989-06-01
The concept of high current ion source is both relative and evolutionary. Within the domain of one particular kind of ion source technology a current of microamperers might be 'high', while in another area a current of 10 Amperes could 'low'. Even within the domain of a single ion source type, what is considered high current performance today is routinely eclipsed by better performance and higher current output within a short period of time. Within their fields of application, there is a large number of kinds of ion sources that can justifiably be called high current. Thus, as a very limited example only, PIGs, Freemen sources, ECR sources, duoplasmatrons, field emission sources, and a great many more all have their high current variants. High current ion beams of gaseous and metallic species can be generated in a number of different ways. Ion sources of the kind developed at various laboratories around the world for the production of intense neutral beams for controlled fusion experiments are used to form large area proton deuteron beams of may tens of Amperes, and this technology can be used for other applications also. There has been significant progress in recent years in the use of microwave ion sources for high current ion beam generation, and this method is likely to find wide application in various different field application. Finally, high current beams of metal ions can be produced using metal vapor vacuum arc ion source technology. After a brief consideration of high current ion source design concepts, these three particular methods are reviewed in this paper
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Ion sources development at GANIL for radioactive beams and high charge state ions
International Nuclear Information System (INIS)
Leroy, R.; Barue, C.; Canet, C.; Dupuis, M.; Flambard, J.L.; Gaubert, G.; Gibouin, S.; Huguet, Y.; Jardin, P.; Lecesne, N.; Leherissier, P.; Lemagnen, F.; Pacquet, J.Y.; Pellemoine-Landre, F.; Rataud, J.P.; Saint-Laurent, M.G.; Villari, A.C.C.; Maunoury, L.
2001-01-01
The GANIL laboratory has in charge the production of ion beams for nuclear and non nuclear physics. This article reviews the last developments that are underway in the fields of radioactive ion beam production, increase of the metallic ion intensities and production of highly charges ion beams. (authors)
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Salt stress induced ion accumulation, ion homeostasis, membrane ...
African Journals Online (AJOL)
Salt stress induced ion accumulation, ion homeostasis, membrane injury and sugar contents in salt-sensitive rice ( Oryza sativa L. spp. indica ) roots under isoosmotic conditions. ... The accumulation of sugars in PT1 roots may be a primary salt-defense mechanism and may function as an osmotic control. Key words: ...
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Jo, Se-Hee; Park, Chanhun; Yi, Sung Chul; Kim, Dukjoon; Mun, Sungyong
2011-08-19
A three-zone carousel process, in which Cu(II)-imprinted polymer (Cu-MIP) and a buffer solution were employed as adsorbent and eluent respectively, has been developed previously for continuous separation of Cu²⁺ (product) from Mn²⁺ and Co²⁺ (impurities). Although this process was reported to be successful in the aforementioned separation task, the way of using a buffer solution as eluent made it inevitable that the product stream included the buffer-related metal ions (i.e., the constituent metal ions of the buffer solution) as well as copper ions. For a more perfect recovery of copper ions, it would be necessary to improve the previous carousel process such that it can remove the buffer-related metal ions from copper ions while maintaining the previous function of separating copper ions from the other 2 impure heavy-metal ions. This improvement was made in this study by proposing a four-zone carousel process based on the following strategy: (1) the addition of one more zone for performing the two-step re-equilibration tasks and (2) the use of water as the eluent of the washing step in the separation zone. The operating conditions of such a proposed process were determined on the basis of the data from a series of single-column experiments. Under the determined operating conditions, 3 runs of carousel experiments were carried out. The results of these experiments revealed that the feed-loading time was a key parameter affecting the performance of the proposed process. Consequently, the continuous separation of copper ions from both the impure heavy-metal ions and the buffer-related metal ions could be achieved with a purity of 91.9% and a yield of 92.8% by using the proposed carousel process based on a properly chosen feed-loading time. Copyright © 2011 Elsevier B.V. All rights reserved.
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Optical effects of ion implantation
International Nuclear Information System (INIS)
Townsend, P.D.
1987-01-01
The review concerns the effects of ion implantation that specifically relate to the optical properties of insulators. Topics which are reviewed include: ion implantation, ion range and damage distributions, colour centre production by ion implantation, high dose ion implantation, and applications for integrated optics. Numerous examples are presented of both diagnostic and industrial examples of ion implantation effects in insulators. (U.K.)
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Simulation study on ion extraction from electron cyclotron resonance ion sources
Fu, S.; Kitagawa, A.; Yamada, S.
1994-04-01
In order to study beam optics of NIRS-ECR ion source used in the HIMAC project, the EGUN code has been modified to make it capable of modeling ion extraction from a plasma. Two versions of the modified code are worked out with two different methods in which 1D and 2D sheath theories are used, respectively. Convergence problem of the strong nonlinear self-consistent equations is investigated. Simulations on NIRS-ECR ion source and HYPER-ECR ion source are presented in this paper, exhibiting an agreement with the experiment results.
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Rotation characteristics of main ions and impurity ions in H-mode tokamak plasma
International Nuclear Information System (INIS)
Kim, J.; Burrell, K.H.; Gohil, P.; Groebner, R.J.; Kim, Y.; St. John, H.E.; Seraydarian, R.P.; Wade, M.R.
1994-01-01
Poloidal and toroidal rotation of the main ions (He 2+ ) and the impurity ions (C 6+ and B 5+ ) in H-mode helium plasmas have been measured via charge exchange recombination spectroscopy in the DIII-D tokamak. It was discovered that the main ion poloidal rotation is in the ion diamagnetic drift direction while the impurity ion rotation is in the electron diamagnetic drift direction, in qualitative agreement with the neoclassical theory. The deduced radial electric field in the edge is of the same negative-well shape regardless of which ion species is used, validating the fundamental nature of the electric field in L-H transition phenomenology
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Atmospheric ions and pollution
International Nuclear Information System (INIS)
Renoux, A.
1977-01-01
The various types of atmospheric ions are defined, the main sources of natural atmospheric radioactivity inducing the formation of radioactive ions in the air are then recalled. The basic equations governing the formation of these ions are indicated and the most current experimental methods used for detecting them are described (Zeleny tubes, Erikson tubes). The special properties of these ions are examined, they are particularly emphasized for the smaller ones. The existence of a discret spectrum of mobilities is shown and the presence of big negative radioactive ions is investigated. Indicative information are given on the granulometric distribution of the atmospheric radioactivity in the air, from small positive Ra A ion fixation on aerosols [fr
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Ion emission microscope microanalyzer
International Nuclear Information System (INIS)
Cherepin, V.T.; Olckovsky, V.L.
1977-01-01
In the ion microanalyzer (microprobe) the object is exposed to the bombardment of a highly focused ion beam, the secondary ions emitted from the object being analyzed by means of a mass filter. In order to be able to control the position of an analysis synchronous to the local analysis of an object an ion-optical converter (electron image with a fluorescent screen) is placed behind the aperture diaphragm in the direction of the secondary ion beam. The converter allows to make visible in front of the mass filter a non-split ion image characterizing the surface of the surface investigated. Then a certain section may be selected for performing chemical and isotope analyses. (DG) [de