1,535 research outputs found
Estructura en escamas del sector noroccidental de la Sierra de Cazorla (zona prebética) y del borde de la depresión del Guadalquivir (provincia de Jaén)
The succession of different stages of deformation, the last of them having taken place in the middle Miocene, has determined the imbricated structure of the Sierra de Cazorla and the easternmost boundary of the Guadalquivir Basin. The evolution of the structural features is analyzed and a tectonic interpretation of the resulting
structure is attempted
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Metabolic differentiation and intercellular nurturing underpin bacterial endospore formation
Despite intensive research, the role of metabolism in bacterial sporulation remains poorly understood. Here, we demonstrate that Bacillus subtilis sporulation entails a marked metabolic differentiation of the two cells comprising the sporangium: the forespore, which becomes the dormant spore, and the mother cell, which dies as sporulation completes. Our data provide evidence that metabolic precursor biosynthesis becomes restricted to the mother cell and that the forespore becomes reliant on mother cell–derived metabolites for protein synthesis. We further show that arginine is trafficked between the two cells and that proposed proteinaceous channels mediate small- molecule intercellular transport. Thus, sporulation entails the profound metabolic reprogramming of the forespore, which is depleted of key metabolic enzymes and must import metabolites from the mother cell. Together, our results provide a bacterial example analogous to progeny nurturing
Nuestra Experiencia en el Estudio con Ultrasonografía en la Cadera Neonatal
Se estudian mediante ultrasonografía las caderas de 112 recién nacidos
(224 caderas) con signos clínicos de displasia luxante de cadera. Los resultados
se comparan con los datos de exploración clínica y estudio radiográ-
fico poniendo en evidencia las limitaciones diagnósticas de las maniobras
exploratorias clásicas y la radiografía. Concluye que la ultrasonografía es
el método más seguro e inocuo para el diagnóstico precoz de la displasia
luxante de cadera en el recién nacido.The authors are studied by ultrasonography 112 newborns (224
hips) with clinical signs of congenital dysplasia and dislocation of
the hip. The results obtained are compared with clinical findings
and radiographic study emphasizing the diagnostic limitations of
the clasics maneuvistes of physical examination and radiography.
They conclude that the ultrasonography is the most sure method
and innocuous to the early diagnosis of the congenital dysplasia
and dislocation of the hip at the newborn
Los Ultrasonidos en la Cadera Neonatal
Los autores describen la técnica de Estudio mediante Ecografía de la
cadera neonatal, las imágenes normales, los métodos de mediciones y las
características de los distintos grados de displasiaThe authors describe the technique of the study by ultrasound
examination of neonatal hip, normal images, methods of measurement
and characteristics of differents degrees of dysplasi
Study of sdO models: mode trapping
We present the first description of mode trapping for sdO models. Mode
trapping of gravity modes caused by the He/H chemical transition is found for a
particular model, providing a selection effect for high radial order trapped
modes. Low- and intermediate-radial order {\em p}-modes (mixed modes with a
majority of nodes in the P-mode region) are found to be trapped by the C-O/He
transition, but with no significant effects on the driving. This region seems
to have also a subtle effect on the trapping of low radial order {\em g}-modes
(mixed modes with a majority of nodes in the G-mode region), but again with no
effect on the driving. We found that for mode trapping to have an influence on
the driving of sdO modes (1) the mode should be trapped in a way that the
amplitude of the eigenfunctions is lower in a damping region and (2) in this
damping region significant energy interchange has to be produced.Comment: 10 pages, 13 figures, accepted for publication in MNRAS, 2009
December 1
Study of sdO models. Pulsation Analysis
We have explored the possibility of driving pulsation modes in models of sdO
stars in which the effects of element diffusion, gravitational settling and
radiative levitation have been neglected so that the distribution of iron-peak
elements remains uniform throughout the evolution. The stability of these
models was determined using a non-adiabatic oscillations code. We analysed 27
sdO models from 16 different evolutionary sequences and discovered the first
ever sdO models capable of driving high-radial order g-modes. In one model, the
driving is by a classical kappa-mechanism due to the opacity bump from
iron-peak elements at temperature ~200,000 K. In a second model, the driving
result from the combined action of kappa-mechanisms operating in three distinct
regions of the star: (i) a carbon-oxygen partial ionization zone at temperature
~2 10^6 K, (ii) a deeper region at temperature ~2 10^7 K, which we attribute to
ionization of argon, and (iii) at the transition from radiative to conductive
opacity in the core of the star.Comment: 13 pages, 19 figures, accepted for publication in MNRAS, 2009
September 1
The structure and ecological function of the interactions between plants and arbuscular mycorrhizal fungi through multilayer networks
Arbuscular mycorrhizas are one of the most frequent mutualisms in terrestrial
ecosystems. Although studies on plant mutualistic interaction networks suggest
that they may leave their imprint on plant community structure and dynamics,
this has not been explicitly assessed. Thus, in the context of plant-fungi
interactions,
studies explicitly linking plant-mycorrhizal
fungi interaction networks with
key ecological functions of plant communities, such as recruitment, are lacking.
2. In this study, we analyse, in two Mediterranean forest communities of southern
Iberian Peninsula, how plant-arbuscular
mycorrhizal fungi (AMF) networks
modulate plant-plant
recruitment interaction networks. We use a new approach
integrating plant-AMF
and plant recruitment networks into a single multilayer
structure. We also develop a new metric (Interlayer Node Neighbourhood
Integration, INNI) to explore the impact of a given node on the structure across
layers.
3. The similarity of plant species in their AMF communities is positively related to
the observed frequency of recruitment interactions in the field. Results reveal
that properties of plant-AMF
networks, such as plant degree and centrality, can
explain about the properties of plant recruitment network, such as in-and
out-degree
(i.e. sapling bank and canopy service) and its modular structure. However,
these relationships differed between the two forest communities. Finally, we
identify particular AMF that contribute to integrate the neighbourhood of recruitment
interactions between plants.
4. This multilayer network approach is useful to explore the role of plant-AMF
interactions
on recruitment, a key ecosystem function enhanced by fungi. Results
provide evidence that the complex structure of plant-AMF
interactions impacts
functional and structurally plant-plant
interactions, which in turn may potentiallyMinisterio de Ciencia e Innovación, Grant/
Award Number: CGL2015-69118-
C2-
2-
P
and PGC2018-100966-
B-
I0
Bulk dynamics for interfacial growth models
We study the influence of the bulk dynamics of a growing cluster of particles
on the properties of its interface. First, we define a {\it general bulk growth
model} by means of a continuum Master equation for the evolution of the bulk
density field. This general model just considers arbitrary addition of
particles (though it can be easily generalized to consider substraction) with
no other physical restriction. The corresponding Langevin equation for this
bulk density field is derived where the influence of the bulk dynamics is
explicitly shown. Finally, when it is assumed a well-defined interface for the
growing cluster, the Langevin equation for the height field of this interface
for some particular bulk dynamics is written. In particular, we obtain the
celebrated Kardar-Parisi-Zhang (KPZ) equation. A Monte Carlo simulation
illustrates the theoretical results.Comment: 6 pages, 2 figure
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