Concepts and Actors in Organic Livestock Husbandry in Bolivia

Traditional smallholder livestock production is expected to correspond widely with principles of organic livestock farming. Though, the real magnitude of livestock under organic and alike management is unknown. From stakeholder analysis and structured interviews with key persons in Bolivia it is deduced that similarities are widely given, whereas it is questioned whether a formal individual certification approach for livestock products will match the farmer interests and consumer demands

Late Glacial–Holocene climatic transition record at the Argentinian Andean piedmont between 33 and 34° S

The Arroyo La Estacada (~ 33°28' S, 69°02' W), eastern Andean piedmont of Argentina, cuts through an extensive piedmont aggradational unit composed of a dominant Late Pleistocene–early Holocene (LP–EH) alluvial sequence that includes several paleosols. <br><br> One of these paleosols developed affecting the topmost part of likely Late Glacial aeolian deposits aggraded into a floodplain environment by the end of the Late Pleistocene. The paleosol shows variable grade of development along the arroyo outcrops. Organic matter humification, carbonate accumulation and redox processes were the dominant processes associated with paleosol formation. By the early Holocene, when the formation of the paleosol ended, renewed alluvial aggradation and high magnitude flooding events affected the arroyo's floodplain environment. Accordignly, a period of relative landscape stability in the Arroyo La Estacada basin is inferred from the paleosol developed by the LP–EH transition in response to the climatic conditions in the Andes cordillera piedmont after the Late Glacial arid conditions. The analyzed Late Glacial–Holocene alluvial record of the Andean piedmont constitutes a suitable record of the LP–EH climatic transition in the extra-Andean region of Argentina. It is in agreement with regional paleoclimatic evidence along the southern tip of the South American continent, where other pedosedimentary sequences record similar late Quaternary paleoenvironmental changes over both fluvial and interfluvial areas

Decoherence of Einstein-Podolsky-Rosen steering

We consider two systems A and B that share Einstein-Podolsky-Rosen (EPR) steering correlations and study how these correlations will decay, when each of the systems are independently coupled to a reservoir. EPR steering is a directional form of entanglement, and the measure of steering can change depending on whether the system A is steered by B, or vice versa. First, we examine the decay of the steering correlations of the two-mode squeezed state. We find that if the system B is coupled to a reservoir, then the decoherence of the steering of A by B is particularly marked, to the extent that there is a sudden death of steering after a finite time. We find a different directional effect, if the reservoirs are thermally excited. Second, we study the decoherence of the steering of a Schr\"odinger cat state, modeled as the entangled state of a spin and harmonic oscillator, when the macroscopic system (the cat) is coupled to a reservoir

Carl Djerassi: “In memoriam”. Pionero de la creación del “anticonceptivo oral” y hombre polifacético

ResumenCarl Djerassi nació en Viena en 1923 y emigró a New York en 1939 donde escribió una carta a Eleanor Roosevelt solicitando un apoyo para continuar sus estudios, graduándose en química en 1942 y obteniendo su doctorado en química en la Universidad de Wisconsin en 1945. Sintetizó el esteroide básico del “anticonceptivo oral”, genéricamente conocido como noretisterona. Desde el siglo pasado se sabía que la administración parenteral de estrógenos y progesterona inhibía la ovulación, pero resultaba de un costo muy elevado. Jorge Rosenkranz invitó a Djerassi a incorporarse a Syntex para buscar la síntesis de progesterona, quienes junto con Luis E. Miramontes emplearon el esteroide esencial obtenido del barbasco descubierto por Rusell E. Marker. De esta manera se consiguió industrializar el anticonceptivo hormonal oral conocido trivialmente como la “píldora”.Djerassi se podría considerar como un conspicuo químico, biólogo y sociólogo; incursionó en la literatura, fue coleccionista de arte y benefactor de artistas. Fue presidente de Syntex en México y en Palo Alto. Falleció el 30 de enero de 2015 a la edad de 91 años en San Francisco California.AbstractCarl Djerassi (Vienna, 1923) immigrated to New York in 1939, where he wrote to Eleanor Roosevelt requesting funding to continue his studies, graduating in chemistry in 1942, and acquiring a doctorate in chemistry at the University of Wisconsin in 1945. He synthesised the basic “oral contraceptive” steroid, known generically as norethisterone. Since the preceding century parenteral estrogens and progesterone had been known to inhibit ovulation, but producing them was very expensive. Jorge Rosenkranz invited Djerassi to join Syntex to work on progesterone synthesis; together with Luis E. Miramontes, the researchers used the essential steroid from barbasco [a Mexican yam] discovered by Russell E. Marker to make it possible to industrialise the oral hormonal contraceptive commonly known as “the pill”.Djerassi could be considered as a distinguished chemist, biologist and sociologist, who also pursued literature and was an art collector and artists’ benefactor. Past president of Syntex in Mexico and in Palo Alto, he died on 30 January 2015 at the age of 91 in San Francisco, California

On the formations of the Pampas in the footsteps of Darwin: South of the Salado

In 1833 during his journey across the Buenos Aires Pampas, Charles Darwin made observations that reflected his thoughts on two major landscape units, Pampa interserrana and Pampa deprimida, later identified by other authors. Darwin grouped the Pampean sediments into a single unit, the Pampean Formation, based upon the lithological homogeneity and the large extension of the deposits; the unit was thought to be of estuarine-marine origin and attributed to the Recent Epoch considering the paleontological content (vertebrates and mollusks). At present, the Pampean sedimentary succession, which accumulated approximately during the last 11-12 Ma, is interpreted as a pedosedimentary sequence due to the ubiquity of pedogenetic features throughout the deposits. Four main subcycles of sedimentation are identified related to reactivations of the Pampean landscape. At a regional scale, the outcrop distribution of Pampean sediments of different ages suggests the dominance of more stable conditions since the late Miocene-Pliocene in a vast area of Pampa interserrana, documented by the formation of calcretes. However, sedimentation during the late Pliocene-Pleistocene was active within the domain of the Salado tectonic basin and Sierras de Tandil. The regional disparity shown by the Pampean stratigraphic record reveals the major morphostructural differences of its basement.Fil:Folguera, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Dynamics of fluctuations in a fluid below the onset of Rayleigh-B\'enard convection

We present experimental data and their theoretical interpretation for the decay rates of temperature fluctuations in a thin layer of a fluid heated from below and confined between parallel horizontal plates. The measurements were made with the mean temperature of the layer corresponding to the critical isochore of sulfur hexafluoride above but near the critical point where fluctuations are exceptionally strong. They cover a wide range of temperature gradients below the onset of Rayleigh-B\'enard convection, and span wave numbers on both sides of the critical value for this onset. The decay rates were determined from experimental shadowgraph images of the fluctuations at several camera exposure times. We present a theoretical expression for an exposure-time-dependent structure factor which is needed for the data analysis. As the onset of convection is approached, the data reveal the critical slowing-down associated with the bifurcation. Theoretical predictions for the decay rates as a function of the wave number and temperature gradient are presented and compared with the experimental data. Quantitative agreement is obtained if allowance is made for some uncertainty in the small spacing between the plates, and when an empirical estimate is employed for the influence of symmetric deviations from the Oberbeck-Boussinesq approximation which are to be expected in a fluid with its density at the mean temperature located on the critical isochore.Comment: 13 pages, 10 figures, 52 reference

VIVIR EN RÉGIMEN DE CONDOMINIO: CONFLICTOS VECINALES EN VIVIENDA DE INTERÉS SOCIAL, TIJUANA, BAJA CALIFORNIA.

En este trabajo se analizan los conflictos vecinales derivados del régimen de propiedad en condominio, bajo el cual se adquieren las viviendas de interés social promovidas por las instituciones del gobierno mexicano, así como por desarrolladores privados. Este régimen ha facilitado el acceso a la vivienda a la población asalariada, pero está lejos de contribuir a la consecución del derecho a la misma. La investigación toma como casos de estudio conjuntos habitacionales ubicados en la ciudad de Tijuana, Baja California, México. El análisis incluyó una metodología mixta. En primer lugar, se analizaron casos de estudio similares; en segundo lugar, se realizó la revisión de la Ley del Régimen de Propiedad en Condominio para conocer sus implicaciones. Ante la situación de pandemia, se aplicó una encuesta de manera virtual a los habitantes de estas zonas, así como entrevistas con presidentes de comités vecinales de estos conjuntos. A partir de lo anterior, se pudo constatar que esta forma de propiedad genera conflictos, reflejados en la insatisfacción de los habitantes con su vivienda, desacuerdos y controversias en su organización y convivencia. Los habitantes tienen que resolver de forma colectiva las problemáticas que enfrentan, relacionadas con el mantenimiento y uso de áreas comunes, inseguridad, limpieza, entre otros. Además, se observa la falta de apoyo de las autoridades locales. Con ello, se concluye que si bien los habitantes cuentan con un espacio que resuelve su problema de alojamiento, no logra ser un espacio que garantice adecuadamente su derecho a la vivienda