273 research outputs found
Understanding Knowledge and creativity-based development in well-established cities and urban regions
Interregional mobility of talent in Spain: The role of job opportunities and qualities of places during the recent economic crisis
This paper seeks to extend our knowledge of the drivers behind talented workers’ mobility within the Spanish urban system and the patterns they may follow. For this purpose, the stock and flows of creative workers (selected on the basis of either the industry-based or occupational approaches) are studied at different spatial scales while also considering the influence of local characteristics as a source of attracting and retaining forces. The study is based on the analysis of a quite novel longitudinal micro-database from the Spanish Social Security office. Under the conditions of lower mobility of creative workers compared with other geographical contexts –a trend worsened by the economic crisis– we show that job opportunities, especially in connection with workers’ social networks, emerge as the most influential attracting factor. Thus, beyond the classic idea that agglomeration economies benefit all residents, we found evidence that the biggest cities, and Madrid in particular, had become “escalator regions”, propelling the careers of young creative workers that had been attracted to them. On the contrary, the influence of urban amenities seems limited to the retention of talent. This research aims to contribute to dealing with the challenge of upgrading local productive forces after the economic crisis and to develop tailor-made talent attraction and retention strategies.Fac. de Geografía e HistoriaTRUEMinisterio de Ciencia e Innovación (MICINN)/FEDERpu
Perfiles paleokarsticos en el techo de la unidad intermedia del mioceno de la cuenca de Madrid
An intra-Vallesian (Upper Miocene) paleokarst developed at the top of the Intermediate Miocene Unit in the continental Madrid basin is recognized. This paleokarst is a early shallow, tabular-shaped karst that shows a marked control by the depositional facies pattern and lithologies. By integrating morphological, petrological and geochemica1 data, three hydrogeological or environmental zones have been established throughout the paleokarstic profiles: (i) a vadose zone, characterized by vertically elongated caves and discontinuous speleothems and vadose cements (ii) a 3-7 m thick water table fringe, characterized by the wide development of stratiform breccia bodies, the superimposition of both vadose and phreatic features, and the lowest Fe and Mn contents in host-rock carbonates; and (iii) a phreatic zone characterized by an increase of 6I3C values and the predominance of phreatic cementation. The paleogeographic reconstruction for the intra-Vallesian paleokarst using paleokarstic profiles reveals relative topographic highs to the north and topographic lows to the south drawing the paleokarst landscape.En el techo de la Unidad Intermedia del Mioceno de la Cuenca de Madrid se ha desarrollado un paleokarst temprano, somero y de forma tabular que muestra un marcado control litológico y del dispositivo de facies deposicionales en su génesis. Integrando criterios geomorfológicos, petrográficos y geoquímicos se ha establecido una zonación hidrogeológica en los perfiles paleokársticos estudiados, diferenciándose: (i) una zona vadosa caracterizada por la existencia de cavidades alargadas en la vertical tapizadas discontinuamente por espeleotemas y otros cementos vadosos; (ii) una franja de oscilación del nivel freático de unos 3-7 metros de espesor, caracterizado por el desarrollo extensivo de cuerpos brechoides estratiformes, la yuxtaposición de cementos vadosos y freáticos y los contenidos más bajos en Fe y Mn en el material encajante, y (iii) una zona freática caracterizada por un aumento en los valores de 613C y el predominio de la cementación freática. La correlación de los perfiles paleokárticos revela una paleogeografía para el techo de la Unidad Intermedia con un paisaje topográficamente descendente de norte a sur en la cuenca para el Vallesiense
An in vitro experimental investigation of oscillatory flow in the cerebral aqueduct
This in vitro study aims at clarifying the relation between the oscillatory flow of cerebrospinal fluid (CSF) in
the cerebral aqueduct, a narrow conduit connecting the third and fourth ventricles, and the corresponding
interventricular pressure difference. Dimensional analysis is used in designing an anatomically correct scaled
model of the aqueduct flow, with physical similarity maintained by adjusting the flow frequency and the
properties of the working fluid. The time-varying pressure difference across the aqueduct corresponding
to a given oscillatory flow rate is measured in parametric ranges covering the range of flow conditions
commonly encountered in healthy subjects. Parametric dependences are delineated for the time-averaged
pressure fluctuations and for the phase lag between the transaqueductal pressure difference and the flow
rate, both having clinical relevance. The results are validated through comparisons with predictions obtained
with a previously derived computational model. The parametric quantification in this study enables the
derivation of a simple formula for the relation between the transaqueductal pressure and the stroke volume.
This relationship can be useful in the quantification of transmantle pressure differences based on non-invasive
magnetic-resonance-velocimetry measurements of aqueduct flow for investigation of CSF-related disorders.National Institutes of Health/
National Institute of Neurological Diseases and Stroke through contract
# 1R01NS120343-0
Caracterización microambiental de la Cueva de Pozalagua (Vizcaya): aplicación a la gestión y protección de cavidades turísticas
There are summarized the data obtained after monitoring some microenvironmental parameters in the Pozalagua cave from 1st April 2001 to 1st july 2002. The singularity of this show cave is because the high amount of helictites type speleothems. Host rock, speleothems and infiltration waters have been analysed as well as the effect of the visits into the cave have been evaluated. It is stated that visits influence the temperature and CO2 levels inside the cave and the natural system need some time in recover from this changes. During massive visits increase in cave temperature is over the natural annual thermal oscillation. Management guidelines focused in visits schedule have been proposed in order to minimize the effects of the visits and to keep the cave microenvironment near the natural conditions.Se presentan los datos obtenidos tras el registro en continuo de diversos parámetros microambientales en la Cueva de Pozalagua (Vizcaya) durante el período del 1 de abril de 2001 al 1 de julio de 2002. La singularidad de esta cueva turística se debe a la alta presencia de espeleotemas tipo excéntricas o helictitas. Tras la caracterización de la roca encajante y diversos espeleotemas, así como de la hidroquímica de las aguas de infiltración que circulan por la misma, se ha evaluado el efecto que tienen las visitas turísticas en esta cavidad. Se constata que las visitas influyen claramente en la temperatura de la cavidad y en los niveles de CO2 de la misma, de lo que el sistema natural tarda tiempo en recuperarse. En períodos de visitas masivas se ha comprobado que el incremento de temperatura que se produce en la cavidad es superior a la oscilación térmica natural de la misma durante un ciclo anual. Se proponen medidas de gestión de la cavidad, principalmente enfocadas a optimizar el régimen de visitas, que minimicen el impacto de las mismas y que permitan mantener las condiciones microambientales de la cavidad cercanas a las condiciones originales naturales
Causas y mecanismos de deterioro de los materiales pétreos del pavimento del conjunto arqueológico de Baelo Claudia, Cádiz/España
A detailed study of the alteration causes in the stone material used in buildings and pavements from the ancient roman town of Baelo Claudia (Cádiz, South Spain) was carried out to establish their degree of conservation. Slabs from the pavement of the Forum showed in general a high and irreversible degree of degradation. In order to palliate the action of processes of degradation in subaerial conditions, in this work some measures are proposed to try to preserve the slabs in better conditions.En este trabajo se muestran los resultados de un estudio detallado sobre el estado de conservación de los materiales pétreos usados en construcciones y pavimentos de la antigua ciudad romana de Baelo Claudia (Cádiz, Sur de España). En especial, las losas del pavimento del Foro romano mostraron, en general, un alto e irreversible grado de alteración. En este estudio, se proponen medidas correctoras para una mejor preservación de las losas, amortiguando la acción de los procesos de degradación propios de condiciones subaéreas
Larger in the disc of isolated active spiral galaxies than in their non-active twins
We present a comparison of the spin parameter , measured in a
region dominated by the galaxy disc, between 20 pairs of nearby
(0.005z0.03) seemingly isolated twin galaxies differing in nuclear
activity. We find that 80--82% of the active galaxies show higher values of
than their corresponding non-active twin(s), indicating larger
rotational support in the AGN discs. This result is driven by the 11 pairs of
unbarred galaxies, for which 100% of the AGN show larger than their
twins. These results can be explained by a more efficient angular momentum
transfer from the inflowing gas to the disc baryonic matter in the case of the
active galaxies. This gas inflow could have been induced by disc or bar
instabilities, although we cannot rule out minor mergers if these are prevalent
in our active galaxies. This result represents the first evidence of
galaxy-scale differences between the dynamics of active and non-active isolated
spiral galaxies of intermediate stellar masses (10
M) in the Local Universe.Comment: 11 pages, 7 figures. Accepted for publication in A&A Letter
A study on the state of conservation of the Roman Necropolis of Carmona (Sevilla, Spain)
The Roman Necropolis of Carmona (Sevilla, Spain) has experienced a severe deterioration since the accidental discovery in 1868 and subsequent archaeological excavations starting in 1882. To this deterioration contributed the location in a soft calcarenite rock quarry, the adverse environmental conditions and the numerous and extensive wrong archaeological and managing interventions along more than a century. The cultural, artistic and religious importance of this Necropolis converts the protection and conservation of this archaeological site in a major issue. This work present the data obtained in a multidisciplinary research were geology, geomorphology, micro-environmental and climatic monitoring, rock petrophysical characterization, description of weathering forms and biological colonization were considered in order to propose corrective measures to minimize deterioration
Síntesis de la cronoestratigrafía y evolución sedimentaria de los sistemas lacustres evaporíticos y carbonatados neógenos de la Cuenca de Calatayud-Montalbán.
La Cuenca terciaria de Calatayud-Montalbán consta de dos subcuencas diferentes separadas por el umbral de Daroca (Cuenca de Calatayud en el sector septentrional y Cuenca de Montalbán en el sector meridional). Estas cuencas presentan una evolución sedimentaria muy similar de los sistemas lacustres neógenos evaporíticos y carbonáticos, que generalmente ocupan los sectores centrales de ambas depresiones. En la Cuenca de Calatayud, se reconocen tradicionalmente en el Neógeno tres unidades sedimentarias
mayores denominadas Unidad Inferior, Intermedia y Superior separadas por dos rupturas sedimentarias principales. Las dos primeras tienen carácter evaporítico, mientras que la
última tiene un carácter fluviolacustre. En los sectores centrales de la Cuenca de Montalbán, el sondeo Barrachina-l y las secciones estratigráficas complementarias han permitido apreciar una evolución sedimentaria muy similar para las unidades neógenas, con facies evaporíticas y carbonáticas muy parecidas, aunque con una cronoestratigrafía diferente y la ausencia del registro sedimentario del Mioceno medio a Plioceno. En este trabajo
también se describe por vez primera la presencia de un nivel volcanoclástico intercalado entre las facies evaporíticas del Mioceno inferior de la Cuenca de Montalbán. Las asociaciones minerales identificadas en los depósitos lacustres del Mioceno inferiormedio de ambos sectores de la cuenca, muestran una secuencia que evoluciona desde facies lacustres evaporíticas de alto grado de hipersalinidad, hacia facies lacustres evaporíticas
de baja-moderada salinidad. Solamente, el registro sedimentario de la Cuenca de Calatayud permite asegurar que esta evolución sedimentaria se completa con la presencia
de facies carbonáticas fluviolacustres características de aguas dulces en el Mioceno superior. Esta secuencia de precipitación salina responde a un cambio progresivo en la
hidroquímica de los sistemas lacustres relacionado con un cambio gradual de las condiciones climáticas que comenzaría en el Rambliense y se extendería, al menos, durante todo el Mioceno medio. Las diferencias cronoestratigráficas entre los dos sectores de la misma depresión deben estar relacionados con los diferentes condicionantes tectónicos y/o geomorfológicos a los que se han visto sometidas ambas cuencas durante el Mioceno.
[ABSTRACT]
The Tertiary Calatayud-Montalbán Basin consists of two distinct sub-basins separated by the Daroca High (Calatayud Basin in the northern sector and Montalbán Basin in the southern sector). These basins present a quite similar sedimentary evolution of the Neogene evaporitic and carbonatic lacustrine systems, that generally occupy central
locations in both basins. Three main sedimentary units (Lower, Intermediate and Upper units) divided by two main sedimentary breaks are traditionally described in the Calatayud Basin. The Lower and Intermediate units have evaporitic sedimentation, whilst the Upper Unit is tipically freshwater fluviolacustrine sedimentation. In the central areas of the Montalbán basin, the Barrachina-l drill hole and complementary stratigraphic sections
showed a very similar sedimentary evolution of the Neogene units, with similar evaporitic and carbonatic facies, but different chronostratigraphy. The Upper MiocenePliocene
sedimentary record of the Montalbán Basin is absent. In addition, this work presents the first occurrence of a volcanoclastic layer interbedded in the Lower Miocene
evaporitic facies of the Montalbán Basin. The identified mineral assemblages of the lacustrine deposits of both sectors of the basin, show an evolutionary sequence during
the Lower-Middle Miocene from hypersaline to lower moderated salinity lacustrine facies. This evolutionary trend is only complete in the sedimentary record of the Calatayud Basin, where freshwater carbonatic fluviolacustrine facies are described in the Upper Miocene. This precipitation sequence is the result of a progressive hydrochemical change of the lacustrine systems related to a climatic change from the Ramblian to the Middle Miocene. Differences in the chronostratigraphy of both basins should be related to distinct tectonic scenarios and/or geomorphologic features during the Miocene
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