The Philosophical Forum. Published with the cooperation of the Departament of Philosophy of Baruch College of the City University of New York, v. XX, n. 1-2, Fall-Winter 1988-89

Fil: Jalif de Bertranou, Clara Alicia.

Evaluation of the attack rates and level of damages by the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), affecting corn-crops in the northeast of Argentina

The fall armyworm (FAW) is the most important threat to corn crops in Argentina, and there exists very little up-to-date information on its actual pest status because the available literature was published more than 20 years ago. Therefore, field surveys were carried out in the northeast of Argentina, in order to establish the attack rates and injury levels of the pest in relation to the crop phenology. The study was carried out at two localities: Colonia Benítez, an agricultural region, and Tapenagá, a cattle-raising area. At each site two 1-ha plots were sown either with a Bt-corn expressing Cry 1F protein or with an untransformed corn germplasm. Optimal and late sowing was assayed and FAW larval abundance, relative age composition, attack rates and level of damage to corn were recorded. At the moment of the field experiments, Bt-corn was not affected by FAW larvae. However, untransformed germplasms were severely affected by FAW larvae, with an average of attacked plants of 18% or more. In contrast to data obtained 30 years ago, higher values of FAW density were registered. Levels of damage to corn plants were higher after the V4 stage. It was found that the sowing date affected the infestation levels and early seeding avoided high armyworm densities that develop later in the season; in northern Argentina, this was only relevant in agricultural areas.

Trabajadores en las calles : un análisis de las movilizaciones obreras en Buenos Aires, 1888-1896

En la última década del siglo XIX se produjo un destacado salto en la agitación obrera en la ciudad de Buenos Aires. Si bien el eje de la actividad de las sociedades y comisiones obreras fue la agitación huelguística, a lo largo de todos estos años los trabajadores porteños también llevaron adelante otro tipo de acciones, entre las cuales se destacan una serie de importantes movilizaciones callejeras. En muchos casos eran manifestaciones convocadas por gremios que se encontraban en conflicto y pretendían con una movilización callejera difundir sus reivindicaciones y reforzar su capacidad de presión frente a los empresarios. En otros casos se trataba de manifestaciones convocadas para celebrar el aniversario de una sociedad de resistencia o algún otro evento importante para la vida de los gremios obreros. En este artículo desarrollamos un análisis específico sobre las características, asistencia, recorridos, dinámica y discursos de estas movilizaciones obreras, así como de la respuesta que recibieron por parte de las autoridades y la policía, que estuvieron lejos de tener una actitud condescendiente para con los trabajadores movilizados.

Horizontal profiles of longwave and shortwave radiation components over sea ice near Barrow, Alaska during the 2011 melt

An integrated instrument package for measuring and understanding the surface radiation budget of sea ice is presented, along with results from its first deployment. The setup simultaneously measures broadband fluxes of upwelling and downwelling terrestrial and solar radiation (four components separately), spectral fluxes of incident and reflected solar radiation, and supporting data such as air temperature and humidity, surface temperature, and location (GPS), in addition to photographing the sky and observed surface during each measurement. The instruments are mounted on a small sled, allowing measurements of the radiation budget to be made at many locations in the study area to see the effect of small-scale surface processes on the large-scale radiation budget. Such observations have many applications, from calibration and validation of remote sensing products to improving our understanding of surface processes that affect atmosphere-snow-ice interactions and drive feedbacks, ultimately leading to the potential to improve climate modelling of ice-covered regions of the ocean. The photographs, spectral data, and other observations allow for improved analysis of the broadband data. An example of this is shown by using the observations made during a partly cloudy day, which show erratic variations due to passing clouds, and creating a careful estimate of what the radiation budget along the observed line would have been under uniform sky conditions, clear or overcast. Other data from the setup's first deployment, in June 2011 on fast ice near Point Barrow, Alaska, are also shown; these illustrate the rapid changes of the radiation budget during a cold period that led to refreezing and new snow well into the melt season.