196 research outputs found
Cuantificación del crecimiento de pliegues con sedimentos sintectónicos asociados: aplicación al anticlinal de Santarén (orógeno cubano, cuenca de antepaís de las Bahamas)
The Santaren anticline, located offshore, is the outermost structure of the Cuban fold and thrust belt. The detailed study of the geometry of the syntectonic sediments associated with this anticline has allowed us to document its kinematic evolution. A number of reverse modelling geometrical techniques have been used to quantify fold gr owth (crestal structural relief, shortening, limb dip, interlimb angle and axial plane dip) during different stages. The values obtained for each of these parameters have been plotted versus time in order to s h ow their evolution through time. The conclusions achieved from all these plots are consistent and enable us to understand how fold amplification took place. Thus, the data obtained indicate that fold gr owth initiated during Middle Eocene, or before, and it continued until present day. Fold amplification took place at extremately slow rates from Middle Miocene to present day, and perhaps faster during deposition of older growth strata. In particular, data concerning rotation of the southern limb and interlimb angle tightening support this hypothesis. The data presented in this paper regarding the Santaren anticline evolution disagree with previous plate tectonic models that postulate the end of tectonic activity in this region during Middle Eocene
Cuantificación del crecimiento de pliegues con sedimentos sintectónicos asociados: aplicación al anticlinal de Santarén (orógeno cubano, cuenca de antepaís de las Bahamas)
El estudio detallado de la geometría de los sedimentos sintectónicos asociados al crecimiento del anticlinal de Santaren, localizado bajo el mar en la parte más externa de la faja plegada cubana, ha permitido documentar la evolución cinemática de dicho pliegue.
Para ello se han utilizado una serie de técnicas geométricas de modelización inversa que permiten cuantificar el crecimiento del pliegue en función de: el relieve estructural de la cresta, el acortamiento, el buzamiento de los flancos, el ángulo entre flancos y el buzamiento del plano axial para diferentes estadios durante el depósito de los sedimentos sintectónicos. Para cada uno de los parámetros, los valores obtenidos se representan en una gráfica con respecto a la edad correspondiente, y de esta manera se conoce su evolución a través del tiempo.
Las conclusiones que se obtienen a partir de las diferentes gr á ficas son coherentes entre sí y permiten vislumbrar datos importantes de la evolución del pliegue. Así, los resultados obtenidos indican que el anticlinal se inició en el Eoceno Medio, o anteriormente, y su crecimiento perduró hasta la actualidad. El anticlinal creció de forma extremadamente lenta a partir del Mioceno Medio y tal vez lo hizo de forma mas rápida durante el depósito de los sedimentos sintectónicos más antiguos.
En particular, los datos sobre la rotación del flanco sur del anticlinal y sobre la variación del ángulo entre flancos parecen estar de acuerdo con esta última hipótesis. Estos nuevos datos sobre la evolución del anticlinal de Santaren contradicen modelos previos que postulan que la deformación en esta región culminó en el Eoceno Medio.The Santaren anticline, located offshore, is the outermost structure of the Cuban fold and thrust belt. The detailed study of the geometry of the syntectonic sediments associated with this anticline has allowed us to document its kinematic evolution. A number of reverse modelling geometrical techniques have been used to quantify fold gr owth (crestal structural relief, shortening, limb dip, interlimb angle and axial plane dip) during different stages. The values obtained for each of these parameters have been plotted versus time in order to s h ow their evolution through time.
The conclusions achieved from all these plots are consistent and enable us to understand how fold amplification took place. Thus, the data obtained indicate that fold gr owth initiated during Middle Eocene, or before, and it continued until present day. Fold amplification took place at extremately slow rates from Middle Miocene to present day, and perhaps faster during deposition of older growth strata.
In particular, data concerning rotation of the southern limb and interlimb angle tightening support this hypothesis. The data presented in this paper regarding the Santaren anticline evolution disagree with previous plate tectonic models that postulate the end of tectonic activity in this region during Middle Eocene
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Epithelial-to-mesenchymal stem cell transition in a human organ: Lessons from Lichen Planopilaris
YesEpithelial-to-mesenchymal transition (EMT) is critical for embryonic development and wound healing, and occurs in fibrotic disease and carcinoma. Here, we show that EMT also occurs within the bulge, the epithelial stem cell (eSC) niche of human scalp hair follicles, during the inflammatory permanent alopecia, lichen planopilaris. We show that a molecular EMT signature can be experimentally induced in healthy human eSCs in situ by antagonizing E-cadherin, combined with transforming growth factor-β1, epidermal growth factor, and IFN-γ administration, which to our knowledge has not been reported previously. Moreover, induction of EMT within primary human eSCs can be prevented and even partially reversed ex vivo by peroxisome proliferator−activated receptor-γ agonists, likely through suppression of the transforming growth factor-β signaling pathway. Furthermore, we show that peroxisome proliferator−activated receptor-γ agonists also attenuates the EMT signature even in lesional lichen planopilaris hair follicles ex vivo. We introduce lichen planopilaris as a model disease for pathological EMT in human adult eSCs, report a preclinical assay for therapeutically manipulating eSC EMT within a healthy human (mini-)organ, and show that peroxisome proliferator−activated receptor-γ agonists are promising agents for suppressing and partially reversing EMT in human hair follicles eSCs ex vivo, including in lichen planopilaris
Defining human-machine micro-task workflows for constitution making
This paper presents a novel task-oriented approach to crowdsource the drafting of a constitution. By considering micro-tasking as a particular form of crowdsourcing, it defines a workflow-based approach based on Onto2Flow, an ontology that models the basic concepts and roles to represent workflow-definitions. The approach is then applied to a prototype platform for constitution-making where human workers are requested to contribute to a set of tasks. The paper concludes by discussing previous approaches to participatory constitution-making and identifying areas for future work.This work is part-funded by FEDER Funds, by the ERDF (European Regional Development Fund) through the COMPETE Programme (Operational Programme for Competitiveness) and by National Funds through the
FCT (Portuguese Foundation for Science and Technology) within the project FCOMP-01-0124-FEDER-028980 (PTDC/EEI-SII/1386/2012). The work of Nuno Luz is supported by the doctoral grant SFRH/BD/70302/2010. The work of Marta Poblet draws from previous research within the framework of the project “Crowdsourcing: instrumentos semánticos para el desarrollo de la participación y la mediación online” (DER 2012-39492-C02-01) by the Spanish Ministry of Economy and Competitiveness.info:eu-repo/semantics/publishedVersio
A multi-disciplinary perspective on emergent and future innovations in peer review [version 1; peer review: 2 approved with reservations]
Peer review of research articles is a core part of our scholarly communication system. In spite of its importance, the status and purpose of peer review is often contested. What is its role in our modern digital research and communications infrastructure? Does it perform to the high standards with which it is generally regarded? Studies of peer review have shown that it is prone to bias and abuse in numerous dimensions, frequently unreliable, and can fail to detect even fraudulent research. With the advent of Web technologies, we are now witnessing a phase of innovation and experimentation in our approaches to peer review. These developments prompted us to examine emerging models of peer review from a range of disciplines and venues, and to ask how they might address some of the issues with our current systems of peer review. We examine the functionality of a range of social Web platforms, and compare these with the traits underlying a viable peer review system: quality control, quantified performance metrics as engagement incentives, and certification and reputation. Ideally, any new systems will demonstrate that they out-perform current models while avoiding as many of the biases of existing systems as possible. We conclude that there is considerable scope for new peer review initiatives to be developed, each with their own potential issues and advantages. We also propose a novel hybrid platform model that, at least partially, resolves many of the technical and social issues associated with peer review, and can potentially disrupt the entire scholarly communication system. Success for any such development relies on reaching a critical threshold of research community engagement with both the process and the platform, and therefore cannot be achieved without a significant change of incentives in research environments
Stability, Electronic Structure and Vibrational Modes of Ti_8C_12 Dimer
We present our density functional results of the geometry, electronic
structure and dissociation energy of Ti_8C_12 dimer. We show that as opposed to
the currently held view that Ti_8C_12 are highly stable monodispersed clusters,
the neutral Ti_8C_12 clusters form covalent bonds and form stable dimers. We
determine that the Ti atoms bond weakly (0.9 eV/bond) to organic ligands such
as ammonia. Alternatively the Met-Car dimer has a cohesive energy of 4.84 eV or
approximately 1.2 eV per bond. While Met-Car dimers are stable, formation of
these dimers may be quenched in an environment that contains a significant
population of organic ligands. The ionization and dissociation energies of the
dimer are of same order which prevents the observation of the dimer in the ion
mass spectroscopy. The analysis of the vibrational frequencies show the
lowest-energy structure to be dynamically stable. We also present infrared
absorption and Raman scattering spectra of the Ti_8C_12 dimer.Comment: 5 pages, 3 figures (Better quality figures available on request).
Physical Review B (Rapid Communication) (2002, in press
Effective storage of electrons in water by the formation of highly reduced polyoxometalate clusters
Aqueous solutions of polyoxometalates (POMs) have been shown to have potential as high-capacity energy storage materials due to their potential for multi-electron redox processes, yet the mechanism of reduction and practical limits are currently unknown. Herein, we explore the mechanism of multi-electron redox processes that allow the highly reduced POM clusters of the form {MO3}y to absorb y electrons in aqueous solution, focusing mechanistically on the Wells–Dawson structure X6[P2W18O62], which comprises 18 metal centers and can uptake up to 18 electrons reversibly (y = 18) per cluster in aqueous solution when the countercations are lithium. This unconventional redox activity is rationalized by density functional theory, molecular dynamics simulations, UV–vis, electron paramagnetic resonance spectroscopy, and small-angle X-ray scattering spectra. These data point to a new phenomenon showing that cluster protonation and aggregation allow the formation of highly electron-rich meta-stable systems in aqueous solution, which produce H2 when the solution is diluted. Finally, we show that this understanding is transferrable to other salts of [P5W30O110]15– and [P8W48O184]40– anions, which can be charged to 23 and 27 electrons per cluster, respectively
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