5,992 research outputs found
Sobre los experimentos de creación de vida de Andrew Crosse
Uno de los personajes más exitosos y conocidos de la historia de la literatura y el cine de ficción es el creado por la escritora Mary Shelley en 1817 en su libro "Frankenstein o el moderno Prometeo". Paradójicamente, uno de los científicos menos conocidos y más misteriosos de la historia de la ciencia británica es Andrew Crosse, el individuo real en el que, según se suele afirmar, Mary Shelley basó su historia(Haining, 1979).
Durante los trabajos de documentación científica de la exposición “CRISTALES: UN MUNDO POR DESCUBRIR” hemos topado con varios artículos sobre este experto en electrocristalización que protagonizó uno de los episodios más controvertidos de la historia de la ciencia del siglo XIX, cuando se dieron a conocer sus experimentos sobre creación de vida en el laboratorio. Los enigmáticos experimentos que dieron lugar a la polémica son muy similares desde el punto de vista químico a los experimentos conocidos como jardines químicos. En este trabajo discuto esta propuesta y su relevancia en el contexto histórico de las investigaciones sobre creación de vida.European Research Council dentro del European Union's Seventh Framework Programme
(FP7/2007-2013)/ERC grant agreement nº 340863Peer reviewe
Privacy-Preserving Reengineering of Model-View-Controller Application Architectures Using Linked Data
When a legacy system’s software architecture cannot be redesigned, implementing
additional privacy requirements is often complex, unreliable and
costly to maintain. This paper presents a privacy-by-design approach to
reengineer web applications as linked data-enabled and implement access
control and privacy preservation properties. The method is based on the
knowledge of the application architecture, which for the Web of data is
commonly designed on the basis of a model-view-controller pattern. Whereas
wrapping techniques commonly used to link data of web applications duplicate
the security source code, the new approach allows for the controlled
disclosure of an application’s data, while preserving non-functional properties
such as privacy preservation. The solution has been implemented
and compared with existing linked data frameworks in terms of reliability,
maintainability and complexity
A non-parametric independence test using permutation entropy
In the present paper we construct a new, simple and powerful test for independence by
using symbolic dynamics and permutation entropy as a measure of serial dependence.
We also give the asymptotic distribution of an affine transformation of the permutation
entropy under the null hypothesis of independence. An application to several daily
financial time series illustrates our approach
Distribution patterns of Hydropsychids and Rhyacophilids species (Trichoptera) in a not regulated Mediterranean river (SW Spain)
This paper investigates the longitudinal ordination of the Hydropsychidae and Rhyacophilidae species present in the high basin of the Hozgarganta River. The ordination of the Hydropsychids species present in the basin show three distribution patterns: Diplectrona felix and Hydropsyche infernalis are confined to the head streams; H. siltalai and H. iberomaroccana are distributed throughout the entire study zone, although the second one does not reach the highest sections of the basin; finally, H. lobata occupies the lowest sections, specially in the main axis of the river. The two Rhyacophila species studied show also a well differentiated distribution. R. fonticola is more abundant in the gorges and high sections, whereas R. munda prefers the riverbed of the main river, although it's also found in some tributaries. Even in these intermediate sections, the segregation between the two species is almost perfect. The water permanence in the riverbeds influences the distribution of some species.We have found that D. felix and H. infernalis inhabit the permanent sections of the stream heads whereas H. iberomaroccana significantly dominates the intermittent ones. H. siltalai, H. lobata, R. fonticola, and R. munda do not show a significant preference for any type of riverbed (permanent, intermittent, or ephemeral). It is interesting to highlight the survival of some H. iberomaroccana larvae in isolated pools during the summer. We suggest the possibility that these larvae survive thanks to the existence of a weak underground flow of subsurface origin between adjacent pools.En el presente trabajo se investiga la ordenación longitudinal de las especies de Hydropsychidae y Rhyacophilidae presentes en la cuenca alta del río Hozgarganta. La ordenación de las especies de Hydropsychidae presentes en la cuenca muestra tres patrones de distribución: Diplectrona felix e Hydropsyche infernalis están confinadas en los arroyos de cabecera; H. siltalai e H. iberomaroccana están distribuidas por toda la zona de estudio, aunque la segunda no alcanza los tramos más altos de la cuenca; por último, H. lobata ocupa los tramos más bajos, especialmente en el eje principal del río. Las dos especies de Rhyacophila estudiadas también muestran una distribución bien diferenciada. R. fonticola es más abundante en las gargantas y tramos altos, mientras que R. munda prefiere el cauce del río principal, aunque también se encuentra presente en algunos tributarios. Incluso en estos tramos intermedios la segregación entre ambas especies es casi perfecta. La permanencia del agua en los cauces influye en la distribución de algunas especies. Hemos encontrado que D. felix e H. infernalis habitan los tramos permanentes de cabecera, mientras que H. iberomaroccana domina de forma significativa en los intermitentes. H. siltalai, H. lobata, R. fonticola y R. munda no muestran una preferencia significativa por algún tipo de cauce (permanente, intermitente o efímero). Es interesante resaltar la supervivencia de algunas larvas de H. iberomaroccana en pozas aisladas durante el verano. Sugerimos la posibilidad de que estas larvas sobrevivan gracias a la existencia de un débil flujo subterráneo de origen freático entre pozas adyacentes
Avoidance Response in Goldfish: Emotional and Temporal Involvement of Medial and Lateral Telencephalic Pallium
The hippocampus and the amygdala are involved in avoidance learning in mammals. The medial and lateral pallia of actinopterygian fish have been proposed as homologous to the mammalian pallial amygdala and hippocampus, respectively, on the basis of neuroanatomical findings. This work was aimed at studying the effects of ablation of the medial telencephalic pallia (MP) and lateral telencephalic pallia (LP) in goldfish on the retention of a conditioned avoidance response previously acquired in two experimental conditions. In the first experiment, fish were trained in nontrace avoidance conditioning. In the second experiment, fish were trained in trace avoidance conditioning in which temporal cues were crucial for the learning process. An MP lesion affected the retention of the avoidance response in both procedures; in contrast, an LP lesion impaired the retention only in the trace-conditioning procedure. These data support the presence of two different systems of memory in fish, based on discrete telencephalic areas: the MP, involved in an emotional memory system; and the LP, involved in a spatial, relational, or temporal memory system. Moreover, these differential effects were similar to those produced by amygdalar and hippocampal lesions in mammals. We conclude that these specialized systems of memory could have appeared early during phylogenesis and could have been conserved throughout vertebrate evolution.Ministerio de Ciencia y Tecnología BF-I2001-3178Ministerio de Ciencia y Tecnología I2000-0315Ministerio de Ciencia y Tecnología I2003-0029Ministerio de Ciencia y Tecnología PB-96-1334Junta de Andalucía CVI-24
Identifying microbial life in rocks: Insights from population morphometry
The identification of cellular life in the rock record is problematic, since microbial
life forms, and particularly bacteria, lack sufficient morphologic complexity to be effectively
distinguished from certain abiogenic features in rocks. Examples include
organic pore-fillings, hydrocarbon-containing fluid inclusions, organic coatings on
exfoliated crystals and biomimetic mineral aggregates (biomorphs). This has led to
the interpretation and re-interpretation of individual microstructures in the rock record.
The morphologic description of entire populations of microstructures, however,
may provide support for distinguishing between preserved micro-organisms
and abiogenic objects. Here, we present a statistical approach based on quantitative
morphological description of populations of microstructures. Images of modern
microbial populations were compared to images of two relevant types of abiogenic
microstructures: interstitial spaces and silica–carbonate biomorphs. For the populations
of these three systems, the size, circularity, and solidity of individual particles
were calculated. Subsequently, the mean/SD, skewness, and kurtosis of the statistical
distributions of these parameters were established. This allowed the qualitative
and quantitative comparison of distributions in these three systems. In addition, the
fractal dimension and lacunarity of the populations were determined. In total, 11
parameters, independent of absolute size or shape, were used to characterize each
population of microstructures. Using discriminant analysis with parameter subsets,
it was found that size and shape distributions are typically sufficient to discriminate
populations of biologic and abiogenic microstructures. Analysis of ancient, yet unambiguously
biologic, samples (1.0 Ga Angmaat Formation, Baffin Island, Canada) suggests
that taphonomic effects can alter morphometric characteristics and complicate
image analysis; therefore, a wider range of microfossil assemblages should be studied
in the future before automated analyses can be developed. In general, however, it is
clear from our results that there is great potential for morphometric descriptions of
populations in the context of life recognition in rocks, either on Earth or on extraterrestrial
bodies.This project has received funding from the European Research
Council (ERC) under the European Union's Horizon 2020 Research and Innovation Program (grant agreement no. 646894 to MVZ)
and under the ERC Seventh Framework Programme FP7/2007-
2013 (grant agreement no. 340863 to JMG-R). JMG-R also acknowledges
the Ministerio de Economía y Competitividad of Spain
through the project CGL2016-78971-P. We are grateful to seven
anonymous reviewers for their helpful comments. We thank four
anonymous reviewers for their useful comments which greatly improved
a previous version of the manuscript. This is IPGP contribution
n°4098
Localized Crystallization of Calcium Phosphates by Light- Induced Processes
Medical treatment options for bones and teeth can be
significantly enhanced by taking control over the crystallization
of biomaterials like hydroxyapatite in the healing process.
Light-induced techniques are particularly interesting for this
approach as they offer tremendous accuracy in spatial
resolution. However, in the field of calcium phosphates, lightinduced
crystallization has not been investigated so far. Here,
proof of principle is established to successfully induce
carbonate-hydroxyapatite precipitation by light irradiation.
Phosphoric acid is released by a photolabile molecule exclusively
after irradiation, combining with calcium ions to form a
calcium phosphate in the crystallization medium. 4-Nitrophenylphosphate
(4NPP) is established as the photolabile molecule
and the system is optimized and fully characterized. A calcium
phosphate is crystallized exclusively by irradiation in aqueous
solution and identified as carbonate apatite. Control over the
localization and stabilization of the carbonate apatite is
achieved by a pulsed laser, triggering precipitation in calcium
and 4NPP-containing gel matrices. The results of this communication
open up a wide range of new opportunities, both in the
field of chemistry for more sophisticated reaction control in
localized crystallization processes and in the field of medicine
for enhanced treatment of calcium phosphate containing
biomaterials.European Research Council for funding
project 101069348 – INPATTOpen Access funding enabled and
organized by Projekt DEA
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