Datos paleoambientales de depósitos fluviales asociados a antiguas presas de pesca en el río Miño, NW Iberia

[Abstract] Fluvial sediments provide environmental records of the Quaternary. In some cases, fluvial deposits are caused by anthropogenic processes that cause changes in the water regime of some river stretches. This is the case of dams. It has been reported that some dams or partial damming systems existed in the past, at least from some thousands of years ago. Such dams were used for fishing purposes and are referred as fishing weirs. In a recently published work it has been demonstrated that a fluvial thick deposit was caused by a damming system in a river of NW Iberia (River Miño, Pontevedra). Optically stimulated luminescence (OSL) provided the burial age of such fluvial deposit, showing a 1300-year-old fluvial record. The sedimentation rates of the record did not match with known climate fluctuations in the area. In this work, the sedimentation phases of such record are identified, and the detrital and organic matter content is studied to assess any change occurred in the environmental and fluvial conditions during the deposition period of the record that ranges from 814±134 to 1837±11 AD.[Resumen] Los sedimentos fluviales pueden proporcionar registros ambientales del Cuaternario. En algunos casos, los depósitos fluviales pueden ser causados por procesos antropogénicos que provocan cambios en el régimen hídrico de algunos tramos de los ríos. Este es el caso de los actuales embalses. Algunos estudios han mostrado que en el pasado existieron algunas presas o sistemas de represas parciales, desde hace al menos algunos miles de años. Esas presas se utilizaban con fines pesqueros y se denominan fishingweirs o en Galicia pesqueiras. En un trabajo reciente se ha estudiado un depósito fluvial causado por un sistema de embalses en un río del noroeste de la Península Ibérica (rio Miño, Pontevedra). Utilizando luminiscencia estimulada ópticamente (OSL) se pudo datar la edad de deposición de estos sedimentos, obteniéndose un registro fluvial de 1300 años de antigüedad. Las tasas de sedimentación del registro no coincidían con las fluctuaciones climáticas conocidas en la zona. En este trabajo se identifican las fases de sedimentación de ese registro y se estudia el contenido detrítico y la materia orgánica para evaluar los posibles cambios que se hayan producido en las condiciones ambientales y fluviales de ese tramo del río durante el período de deposición del registro, que va de 814±134 a 1837±11 d.C

Time on a Rotating Platform

Traditional clock synchronisation on a rotating platform is shown to be incompatible with the experimentally established transformation of time. The latter transformation leads directly to solve this problem through noninvariant one-way speed of light. The conventionality of some features of relativity theory allows full compatibility with existing experimental evidence.Comment: 12 pages, Latex, no figure. Copies available at [email protected] accepted for publication in Found. Phys. Let

Did Strombus survive the Last Interglacial in the Western Mediterranean Sea?

El litoral de Almería constituye el sector más rico del Mediterráneo en niveles tirrenienses, todos ellos conteniendo Strombus bubonius. Cuatro playas diferentes se observan al Este de Almería, la más reciente, datada en 37.720 ± 1.740 años BP (14C) y 39.000 ± 2.000 años BP (Th/U) años BP, está claramente encajada en las anteriores, y a su vez se presenta relacionada con depósitos continentales de abanicos aluviales que constituyen los sistemas más recientes de la costa oriental de Almería. Por otro lado los depósitos tirrenienses de esta región constituyen un claro ejemplo de la distinta distribución espacial de los niveles con S. bubonius, tanto en lo que se refiere al número, cota, o incluso disposición geométrica de los mismos que depende fundamentalmente del marco neotectónico en el que se desarrollen. Por otra parte los autores hacen una llamada de atención sobre el empleo del término «Tirreniense» sugiriendo que se continúe utilizando a éste en el sentido de su definición original «capas que contienen S. bubonius» sin darle un sentido cronoestratigráfico estricto. Asimismo y a la vista de los resultados sería conveniente llevar a cabo una revisión sobre la significación climato-estratigráfica de la entrada del S. bubonius en el Mediterráneo.The warm gastropod Strombus bubonius spread into the Mediterranean Sea during the last interglacial period. Its fossil ocurrence is normally used as a climatostratifraphic indicator of the Tyrrhenian transgression and linked to high sea levels of this episode. However, a sequence of four successive and discordant stratigraphic units containing S. bubonius is observed in the Rambla Amoladeras-Rambla Sepultura compisite section, east of Almería, on the Spanish Mediterranean coast. The youngest unit has been dated between 39.000 and 34.000 y BP, suggesting therefore that S. bubonius survived the last interglacial in the western part of the Mediterranean basin. Reconsideration of the use and meaning of the term «Tyrrhenian» and of the current somewhat confusing terminology is thus required.This study was supported by the Spanish CAICYT (Grant 3.228/79)

Cancer Tissue Engineering: A Novel 3D Polystyrene Scaffold for In Vitro Isolation and Amplification of Lymphoma Cancer Cells from Heterogeneous Cell Mixtures

Isolation and amplification of primary lymphoma cells in vitro setting is technically and biologically challenging task. To optimize culture environment and mimic in vivo conditions, lymphoma cell lines were used as a test case and were grown in 3-dimension (3D) using a novel 3D tissue culture polystyrene scaffold with neonatal stromal cells to represent a lymphoma microenvironment. In this model, the cell proliferation was enhanced more than 200-fold or 20,000% neoplastic surplus in 7 days when less than 1% lymphoma cells were cocultured with 100-fold excess of neonatal stroma cells, representing 3.2-fold higher proliferative rate than 2D coculture model. The lymphoma cells grew and aggregated to form clusters during 3D coculture and did not maintained the parental phenotype to grow in single-cell suspension. The cluster size was over 5-fold bigger in the 3D coculture by day 4 than 2D coculture system and contained less than 0.00001% of neonatal fibroblast trace. This preliminary data indicate that novel 3D scaffold geometry and coculturing environment can be customized to amplify primary cancer cells from blood or tissues related to hematological cancer and subsequently used for personalized drug screening procedures

A Galactic O-Star Catalog

We have produced a catalog of 378 Galactic O stars with accurate spectral classifications which is complete for V<8 but includes many fainter stars. The catalog provides cross-identifications with other sources; coordinates (obtained in most cases from Tycho-2 data); astrometric distances for 24 of the nearest stars; optical (Tycho-2, Johnson, and Stromgren) and NIR photometry; group membership, runaway character, and multiplicity information; and a web-based version with links to online services.Comment: 76 pages, 13 tables, and 3 figures. Accepted for publication in Astrophysical Journal. Online version of the catalog available at http://www.stsci.edu/~jmaiz/GOSmain.htm

The relativistic impulse approximation for the exclusive electrodisintegration of the deuteron

The electrodisintegration of the deuteron in the frame of the Bethe-Salpeter approach with a separable kernel of the nucleon-nucleon interaction is considered. This conception keeps the covariance of a description of the process. A comparison of relativistic and nonrelativistic calculations is presented. The factorization of the cross section of the reaction in the impulse approximation is obtained by analytical calculations. It is shown that the photon-neutron interaction plays an important role.Comment: 31 pages, 14 figures, 1 tabl

Emission Spectrum of a Dipole in a Semi-infinite Periodic Dielectric Structure: Effect of the Boundary

The emission spectrum of a dipole embedded in a semi-infinite photonic crystal is calculated. For simplicity we study the case in which the dielectric function is sinusoidally modulated only along the direction perpendicular to the boundary surface plane. In addition to oscillations of the emission rate with the distance of the dipole from the interface we also observed that the shape of the emission spectrum srongly depends on the \em initial \em phase of the dielectric modulation. When the direction of light propagation inside the periodic structure is not normal to the boundary surface plane we observed aditional singularities in the emission spectrum, which arise due to different angle-dependence of the Bragg stop-band for $TE$ and $TM$ polarizations.Comment: 14 pages, 6 figures, to appear in Phys Rev