Tipos de negación en la lógica contemporánea

Uno de los problemas más interesantes en la teoría lógica actual radica en la determinación de la caracterización formal de la negación y su relación con el lenguaje natural. En el presente trabajo nos proponemos presentar, analizar y comparar las propuestas de H. Curry en Foundations of Mathematical Logic y la de M.Dunn en The Kite of Negations, a los efectos de determinar si dan cuenta de los mismos sistemas lógicos.

Condiciones de trabajo y calidad de vida de los trabajadores rurales de la ganadería ovina en Santa Cruz

Fil: Delgado, Julia. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Una verdadera "isla en el nuevo sur". Las donaciones condicionadas en el arroyo Azul durante el rosismo

En el marco del estudio de la política de tierras fiscales implementada por el gobierno de Rosas en la campaña de Buenos Aires, en el presente trabajo nos proponemos enfocar la atención en la modalidad de las donaciones condicionadas, que sólo se hicieron efectivas en un área de la frontera sur, el arroyo Azul, a partir de 1832. De tal forma, comenzaremos estableciendo las particularidades que presentó su proceso colonizador, para luego analizar el impacto local que tuvo la entrega de predios estatales durante el período 1820-1860, con el objeto de establecer con mayor precisión el peso de las donaciones comparado con otras formas de otorgamiento en la ocupación del espacio y en la estructura de la tenencia del recurso en el lugar. Asimismo, en un último apartado estableceremos las características centrales que manifestaron las transacciones entre particulares, para lograr una mayor definición de los procesos abordados.

Petrography, minerals and isotopic composition at DSDP Leg 66 Holes

We collected 20 carbonate nodules from the inner trench slope deposits of the Middle America Trench area off Mexico. Carbonate nodules are found only within the methane-rich layer beneath the mixed layer of methane and hydrogen sulfide. They have been investigated by microscopic, scanning electron microscopic (SEM), X-ray diffraction, and stable isotopic analytical methods. Calcite, magnesian calcite, dolomite, and rhodochrosite were recognized as carbonate minerals. Each carbonate nodule is usually represented by single species of carbonate minerals. Carbonate nodules are subdivided into micrite nodules and recrystallized nodules according to textural features. The carbonate crystallites in each micrite nodule are equidimensional. Their sizes range from several to 30 µm, as revealed by SEM micrographs. The chemical composition of calcite is changed from pure calcite to high magnesian calcite, as shown by the shift of the (104) reflection in X-ray diffraction patterns. Fe substitution for Ca in dolomite was also observed. Carbon isotopic composition shows an unusually wide range - from -42.9 to +13.5 per mil - in PDB scale, whereas oxygen isotopic compositions of almost all the carbonate nodules are constantly enriched in 18O from +3.4 to +7.60 per mil in PDB scale. These wide variations in carbon isotopic composition indicate several sources for the carbon in carbonate nodules. Carbon with a negative d13C value was derived from biochemical oxidation of methane with a negative d13C value. On the other hand, carbon with positive d13C value was probably formed during methane production in an anoxic condition.

La invención de las masas : Ciudad, corporalidades y culturas. Rosario, 1910-1945

El libro reconstruye una multiplicidad de experiencias y prácticas urbanas. Sus páginas exploran tiempo-espacios, cuerpos, narraciones y esquemas culturales quebrados en una ciudad que se configura en el umbral de lo masivo. Protagonizada por Rosario y sus agentes, la narración transcurre entre el centenario de la Revolución de Mayo y las vísperas del peronismo. Las fiestas del centenario, la formación de dispositivos disciplinarios y biopolíticos para el cultivo de los cuerpos, la producción y diseminación de espacios verdes, la segregación urbana, la cuestión de la vivienda, las asociaciones y movimientos vecinales, las bibliotecas populares, las prácticas futbolísticas, las exhibiciones cinematográficas, los choques de la incultura y la organización de los carnavales dibujan un mapa y un recorrido curvo y complejo. Roldán ensaya la reunión de procesos, fuerzas y vectores dispersos que se chocan, se rompen y transforman. Es la escritura de una confluencia y sus desperfectos. Universos desconectados se ensamblan por yuxtaposición y contraste en una composición que pretende dar vida y movimiento a una multiplicidad social, corporal, cultural, histórica y urbana.

(Table 1) Uncompacted and compacted sedimentation rate values corrected for bedding attitudes at DSDP Leg 66 Holes

Sediment accumulation rates, computed using agesediment thickness curves obtained from DSDP cores, are rarely corrected for compaction or bedding attitude to better approximate true sediment accumulation rates (c.f. van Andel et al., 1975; Davies et al., 1977; and Whitman and Davies, 1979). Variations with depth in either of these factors can hinder interpreting relative rates of sedimentary processes associated with a particular depositional environment. This problem becomes particularly relevant for convergent margin sediments, which often display variable bedding attitudes and pronounced changes in porosity, bulk density, and other parameters related to the compaction process at shallow depth. These rapid shallow changes render correlation of sedimentation rates within a single transect of holes very difficult. Two techniques have been applied to data collected from a transect of holes along the southwestern Mexico continental margin, DSDP Leg 66 (Fig. 1), to correct sediment accumulation rates for variations in compaction and bedding attitude. These corrections should help resolve true fluctuations in accumulation rates and their implications regarding convergent margin processes.

Distribution, origin, and hydrocarbon-potential of organic matter in sediments from DSDP Leg 66 Holes

As part of an ongoing program of organic geochemical studies of sediments recovered by the Deep Sea Drilling Project, we have analyzed the types, amounts, and thermal alteration indices of organic matter collected from the Pacific continental margin of southern Mexico on Leg 66. The samples were pieces of core frozen aboard ship. Some of them were analyzed by pyrolysis, heavy C15+ hydrocarbons, and nonhydrocarbons to help determine their origin and hydrocarbon potential. Our main objectives were to find out how much organic matter was being deposited; to establish whether it derived from marine or terrestrial sources; to determine the controls of deposition of organic matter; to estimate the hydrocarbon potential of the drilled section; and to compare and contrast organic sedimentation here with that on other margins.

Distribution of calcareous nannofossils in upper Cretaceous and Cenozoic sediments of the Kerguelen Plateau

ODP Leg 119 drilled 11 sites on the Kerguelen Plateau (southern Indian Ocean) and Prydz Bay (East Antarctica). Upper Pliocene through Quaternary sediments were recovered at Site 736 on the northern Kerguelen Plateau; calcareous nannofossils occurred in only a few samples. Over 700 m of middle Eocene through Quaternary sediments was cored at Site 737 on the northern Kerguelen Plateau, and calcareous nannofossils are abundant in the middle Eocene through the middle Miocene sediments. Nearly 500 m of sediments ranging from the lower Turanian to the Quaternary was recovered at Site 738 on the southern Kerguelen Plateau; calcareous nannofossils are abundant from the Miocene downward. Calcareous nannofossils are also abundant in the upper Eocene through Miocene section from Site 744 on the southern Kerguelen Plateau. Except for Core 119-746A-13H, the Neogene sequences drilled at deep-water Sites 745 and 746 off the southern Kerguelen Plateau are devoid of calcareous nannofossils. Occurrences of calcareous nannofossils were generally rare and sporadic at Sites 739 and 742 in Prydz Bay and suggest that the diamictite sequences recovered is as old as middle Eocene-early Oligocene age. Other sites drilled in Prydz Bay (Sites 740, 741, and 743) did not yield calcareous nannofossils. Species diversity of calcareous nannofossils was low (about a dozen) in the southern Indian Ocean in the Late Cretaceous. High-latitude nanno floral characteristics are apparent after the Cretaceous/Tertiary boundary extinctions. Cold climatic conditions limited Oligocene calcareous nannofossil assemblages to fewer than a dozen species, and extinctions of species generally were not compensated by originations of new species. Only a few species of calcareous nannofossils were found in the Miocene sequences, in which Coccolithuspelagicus and one or two species of Reticulofenestra exhibit extreme (0%-100%) fluctuations in assemblage dominance, and these fluctuations may reflect rapid fluctuations in the surface-water temperatures. Further deterioration of climate in the late Neogene essentially excluded calcareous nannoplankton from the Southern Ocean. Significantly warmer water conditions during part of the early-middle Pleistocene were inferred by a few lower-middle Pleistocene calcareous nannofossil species found on the Kerguelen Plateau. The calcareous nannofossil zonation of Roth (1978 doi:10.2973/dsdp.proc.44.134.1978) can be applied to the Upper Cretaceous section recovered at Site 738, and the zonation of Okada and Bukry (1980 doi:10.1016/0377-8398(80)90016-X) can be applied without much difficulty to the Paleocene to middle Eocene sequences from the Kerguelen Plateau. However, some conventional upper Paleogene markers are not useful for southern high latitudes, whereas a few nonconventional species events are useful for subdividing the upper Paleogene sequences. The latter species events include the first occurrence (FO) of Reticulofenestra reticulata, the FO and last occurrence (LO) of Reticulofenestra oamaruensis, the LO of Isthmolithus recurvus, and the LO of Chiasmolithus altus. As the Neogene sequences from the southern Indian Ocean contain only a few long-ranging, cold-water species, or are devoid of coccoliths, calcareous nannofossil zonations remain virtually unworkable for the Neogene in the high-latitude southern Indian Ocean as in other sectors of the Southern Ocean.