Detección de Xanthomonas cucurbitae (Bryan) Vauterin et al. afectando frutos de zapallo coreano en Mendoza y San Juan, Argentina

Durante las campañas 2007/08 y 2008/09, en explotaciones comerciales de zapallo coreano (Cucurbita moschata Duch) de las zonas hortícolas de Mendoza y San Juan, se observaron sobre los frutos numerosas lesiones circulares, de 3 a 6 mm de diámetro, de aspecto húmedo, algo deprimidas hacia el centro, con un exudado gomoso color ámbar. Cuando las lesiones superficiales se unían, se desarrollaba una podredumbre gelatinosa hacia el interior de los tejidos, que podía profundizar hasta la cavidad seminal. El resultado final de la afección era una podredumbre seca y costrosa, que abarcaba gran parte del fruto, inutilizándolo para ser comercializado. En follaje también se observaron síntomas de la enfermedad, como manchas cloróticas angulares de 2 a 3 mm de lado, que en ocasiones se fusionaban. El objetivo del presente trabajo fue determinar la etiología de la enfermedad. Para ello, se tomaron y analizaron muestras de frutos y hojas afectadas, durante ambas temporadas. Se concluyó que la sintomatología es causada por una bacteria, que de acuerdo con los estudios morfobioquímicos y patogénicos es Xanthomonas cucurbitae (Bryan) Vauterin et al. Esta investigación constituye la primera cita de este patógeno afectando frutos en Argentina.

Sbatella, José et al. Origen, apropiación y destinos del excedente económico en la Argentina de la posconvertibilidad, Buenos Aires, Colihue, 2012, 163 págs., ISBN 978-987-684-304-1.

Fil: García, Marcos. Universidad Nacional de Cuyo. Facultad de Filosofía y Letras. Instituto Multidisciplinario de Estudios Sociales Contemporáneos

Revisión de un estudio por Koch et al. sobre el impacto de las restricciones al aborto en la mortalidad materna en Chile

En este comunicado se describen las fallas conceptuales y metodológicas graves que invalidan algunas de sus conclusiones concernientes al aborto y a la mortalidad materna del estudio de Koch y otros. Por lo cuál no altera el acervo de evidencia existente sobre el impacto de las restricciones al aborto sobre la mortalidad materna. En particular, dado que las leyes de aborto en Chile ya eran altamente restrictivas antes de 1989, el estudio no demuestra que el restringir significativamente las leyes de aborto no produzca un impacto negativo en la salud de las mujeres.

Beryllium, thorium and protactinium isotope ratios in sediments from the Galapagos microplate

Biogenic particle fluxes from highly productive surface waters, boundary scavenging, and hydrothermal activity are the main factors influencing the deposition of radionuclides in the area of the Galapagos microplate, eastern Equatorial Pacific. In order to evaluate the importance of these three processes throughout the last 100 kyr, concentrations of the radionuclides 10Be, 230Th, and 231Pa, and of Mn and Fe were measured at high resolution in sediment samples from two gravity cores KLH 068 and KLH 093. High biological productivity in the surface waters overlying the investigated area has led to 10Be and 231Pa fluxes exceeding production during at least the last 30 kyr and probably the last 100 kyr. However, during periods of high productivity at the up welling centers off Peru and extension of the equatorial high-productivity zone, a relative loss of 10Be and 231Pa may have occurred in these sediment cores because of boundary scavenging. The effects of hydrothermal activity were investigated by comparing the 230Thex concentrations to the Mn/Fe ratios and by comparing the fluxes of 230Th and 10Be which exceed production. The results suggest an enhanced hydrothermal influence during isotope stages 4 and 5 and to a lesser extent during isotope stage 1 in core KLH 093. During isotope stages 2 and 3, the hydrothermal supply of Mn was deposited elsewhere, probably because of changes in current regime or deep water oxygenation. A strong increase of the Mn/Fe ratio at the beginning of climatic stage 1 which is not accompanied by an increase of the 230Thex concentration is interpreted to be an effect of Mn remobilization and reprecipitation in the sediment.

Reconstruction of sea surface temperature and salinity of the Arabian Sea

High-frequency suborbital variations (Dansgaard-Oeschger cycles) characterize the climatic history of the Northern Hemisphere as observed in Greenland ice cores, deep-sea sediments of the North Atlantic, the Californian borderland, the Arabian Sea, the South China Sea, and the Chinese loess area. Paleoceanographic data from core KL126 from the Bay of Bengal in combination with data from the other Asian monsoonal areas indicate that the feedback processes involving snow and dust of the Tibetan Plateau vary the summer monsoon capacity to transport moisture into central South Asia and into the atmosphere. We postulate that the summer monsoon initiates, amplifies, and terminates these cycles in the Northern Hemisphere.

Magnetostratigraphic age-depth tie points of ODP Leg 208 sites

We report the paleomagnetic and rock magnetic results from discrete sample analysis of sediments from Walvis Ridge, Leg 208 of the Ocean Drilling Program. In an effort to refine the shipboard magnetostratigraphy, alternating field and thermal demagnetization of discrete samples were carried out, predominantly on samples from Sites 1262 and 1267. Results are generally consistent with the shipboard pass-through cryomagnetometer data, though in some cases the discrete samples resolved ambiguities in the reversal record. Significantly, the C24r/C24n reversal boundary was identified at Sites 1262 and 1267, and most boundaries in the Paleocene and Upper Cretaceous sections are now identified to within 10-30 cm. Magnetic mineralogy results show that prior to the late Miocene, the predominant detrital magnetic component was coarse-grained magnetite and that after the late Miocene, titanomagnetite has also been present. This suggests a possible change in detrital source at that time.

Stable carbon and oxygen isotope ratios of Paleogene planktonic foraminifera from the Maud Rise

The oxygen and carbon isotopic composition has been measured for numerous Paleogene planktonic foraminifer species from Maud Rise, Weddell Sea (ODP Sites 689 and 690), the first such results from the Antarctic. The results provide information about large-scale changes in the evolution of temperatures, seasonally, and structure of the upper water column prior to the development of a significant Antarctic cryosphere. The early Paleocene was marked by cooler surface-water conditions compared to the Cretaceous and possibly a less well developed thermocline. The late Paleocene and early Eocene saw the expansion of the thermocline as Antarctic surface waters became warm-temperate to subtropical. The late Paleocene to early Eocene thermal maximum was punctuated by two brief excursions during which time the entire Antarctic water column warmed and the meridional temperature gradient was reduced. The first of these excursions occurred at the Paleocene/Eocene boundary, in association with a major extinction in deep sea benthic foraminifers. The second excursion occurred within the early Eocene at ~54.0 Ma. These excursions are of global importance and represent the warmest intervals of the entire Cenozoic. The excursions were associated with fundamental changes in deep-water circulation and global heat transport. The thermal maximum of the early Eocene ended with the initiation of a long-term cooling trend at 52.0 Ma. This cooling trend was associated with reduced seasonality, and diminished structure and/or duration of the seasonal thermocline. The cooling trend was punctuated by three major cooling steps at 43.0, 40.0, and -36.0 Ma.

Reseña del libro: Filo (en) rompecabezas. Búsqueda colectiva de la memoria histórica institucional (1966-1983) de Graciela Daleo et al (comp.)

Fil: Abbattista, Lucía. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación. Instituto de Investigaciones en Humanidades y Ciencias Sociales (UNLP-CONICET); Argentina.

Sedimentology and planktonioc foraminifera of core SU90-08

The observation by Heinrich (1988) that, during the last glacial period, much of the input of ice-rafted detritus to the North Atlantic sediments may have occurred as a succession of catastrophic events, rekindled interest on the history of the northern ice sheets over the last glacial period. In this paper, we present a rapid method to study the distribution of these events (both in space and time) using whole core low-field magnetic susceptibility. We report on approximately 20 cores covering the last 150 to 250 kyr. Well-defined patterns of ice-rafted detritus appear during periods of large continental ice-sheet extent, although these are not always associated within their maxima. Most of the events may be traced across the North Atlantic Ocean. For the six most recent Heinrich layers (HL), two distinct patterns exist: HL1, HL2, HL4, HL5 are distributed along the northern boundary of the Glacial Polar Front, over most of the North Atlantic between ~40° and 50°N; HL3 is more restricted to the central and eastern part of the northern Atlantic. The Nd-Sr isotopic composition of the material constituting different Heinrich events indicates the different provenance of the two patterns: HL3 has a typical Scandinavia-Arctic-Icelandic 'young crust' signature, and the others have a large component of northern Quebec and northern West Greenland 'old crust' material. These isotopic results, obtained on core SU-9008 from the North American basin, are in agreement with the study by Jantschik and Huon (1992), who used K-Ar dating of silt- and clay-size fractions of an eastern basin core (ME-68-89). These data confirm the large spatial scale of these events, and the enormous amount of ice-rafted detritus they represent.

Mabel Brizuela y María Amelia Hernández (Ed.), Cecilia Asurmendi et al. (Colab.), Cristina Estofán (Coord.). El regreso de Ulises: el mito en la literatura española actual, Universidad Nacional de Córdoba, Córdoba, 2008, 181 pp.

Fil: Hamamé, Graciela Noemí. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Franco Cardini et al. L'Europa del pellegrinaggio, Rimini: II Cerchio, 1998, 123 páginas

Fil: Disalvo, Santiago Aníbal. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Reseña del libro: Filo (en) rompecabezas. Búsqueda colectiva de la memoria histórica institucional (1966-1983) de Graciela Daleo et al (comp.)

Fil: Abbattista, Lucía. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación. Instituto de Investigaciones en Humanidades y Ciencias Sociales (UNLP-CONICET); Argentina.