1,374 research outputs found
Groups of two galaxies in SDSS: implications of colours on star formation quenching time-scales
We have devised a method to select galaxies that are isolated in their dark
matter halo (N=1 systems) and galaxies that reside in a group of exactly two
(N=2 systems). Our N=2 systems are widely-separated (up to
\,200\,\,kpc), where close galaxy-galaxy interactions are not
dominant. We apply our selection criteria to two volume-limited samples of
galaxies from SDSS DR6 with -19 and -20 to study the
effects of the environment of very sparse groups on galaxy colour. For
satellite galaxies in a group of two, we find a red excess attributed to star
formation quenching of 0.15\,\,0.01 and 0.14\,\,0.01 for the -19 and
-20 samples, respectively, relative to isolated galaxies of the same stellar
mass. Assuming N=1 systems are the progenitors of N=2 systems, an
immediate-rapid star formation quenching scenario is inconsistent with these
observations. A delayed-then-rapid star formation quenching scenario with a
delay time of 3.3 and 3.7\,Gyr for the -19 and -20 samples, respectively,
yields a red excess prediction in agreement with the observations. The
observations also reveal that central galaxies in a group of two have a slight
blue excess of 0.06\,\,0.02 and 0.02\,\,0.01 for the -19 and -20
samples, respectively, relative to N=1 populations of the same stellar mass.
Our results demonstrate that even the environment of very sparse groups of
luminous galaxies influence galaxy evolution and in-depth studies of these
simple systems are an essential step towards understanding galaxy evolution in
general.Comment: 17 pages, 11 figures, accepted to MNRA
Nature tourism and Irish film
This article provides a historical overview and reading of seminal Irish film from the perspective of nature tourism. Within Irish cultural studies, tourism is frequently equated with an overly romantic image of the island, which has been used to sell the country abroad. However, using notions like the tourist gaze and taking on board influential debates around space/place, one can posit a more progressive environmental vision of nature and landscape in our readings of film
Resonant cavity photon creation via the dynamical Casimir effect
Motivated by a recent proposal for an experimental verification of the
dynamical Casimir effect, the macroscopic electromagnetic field within a
perfect cavity containing a thin slab with a time-dependent dielectric
permittivity is quantized in terms of the dual potentials. For the resonance
case, the number of photons created out of the vacuum due to the dynamical
Casimir effect is calculated for both polarizations (TE and TM). PACS:
42.50.Lc, 03.70.+k, 42.50.Dv, 42.60.Da.Comment: 4 pages, 1 figur
Landscape Socioecology in the Serpis Valley (10,000–4000 BP)
En este trabajo se discute nuestro enfoque de la modelización del paisaje para la cuenca del Serpis medio (costa mediterránea central de la Península Ibérica) durante el Holoceno. La secuencia arqueológica de estos valles está marcada por la aparición inicial del paquete neolítico alrededor del año 5700 a.C. Examinamos cómo los paisajes responden al modo de vida agrícola, tanto a corto como a largo plazo. Conceptos como el cambio, la adaptación y también la resiliencia proporcionan marcos conceptuales para comprender mejor la forma en que los seres humanos interactúan con su entorno. También ayudan a explicar cómo fenómenos como la introducción inicial de la horticultura simple de cereales o la posterior introducción del cultivo del arado (Bernabeu Aubán 1995) pueden desencadenar procesos con consecuencias a veces impredecibles en los ecosistemas mediterráneos. Estas consecuencias no son inherentemente desastrosas, pero las interacciones entre los ecosistemas y los seres humanos que usan recursos son complejas y a menudo muestran resultados no lineales en sus respuestas a las actuaciones antrópicas. Utilizamos el concepto de socioecología para caracterizar estos sistemas humanos y naturales vinculados estrechamente, ya que estos deben ser un importante foco de interés para la arqueología.In this paper we discuss our approach to landscape modeling for the Holocene middle Serpis drainage system (central Mediterranean Coast of the Iberian Peninsula). The archaeological sequence of these valleys is marked by the initial appearance of the Neolithic package around 5700 BC. We examine how landscapes respond to the agricultural way of life, in both the short and the long term. Concepts like change, adaptation and also resilience provide conceptual frameworks to better understand the way in which humans interact with their surroundings. They also help to explain how phenomena like the initial introduction of simple cereal horticulture, or subsequent introduction of plow cultivation (Bernabeu Aubán 1995) can trigger processes with sometimes unpredictable consequences in Mediterranean ecosystems. These consequences are not inherently disastrous, but the interactions between ecosystems and humans using resources are complex and often display non-linear outcomes of human decisions. We use the concept of socioecology to characterize these closely coupled human and natural systems as these should be an important focus of interest for archaeology
Cloning and functional characterization of the fatty acid elongase 1 (FAE1) gene from high erucic Crambe abyssinica cv. Prophet.
A genomic fatty acid elongation 1 (FAE1) clone was isolated from Crambe abyssinica. The genomic clone corresponds to a 1521-bp open reading frame, which encodes a protein of 507 amino acids. In yeast cells expression of CrFAE led to production of new very long chain monounsaturated fatty acids such as eicosenoic (20:1(delta11)) and erucic (22:1(delta13)) acids. Seed-specific expression in Arabidopsis thaliana resulted in up to a 12-fold increase in the proportion of erucic acid. On the other hand, in transgenic high-erucic Brassica carinata plants, the proportion of erucic acid was as high as 51.9% in the best transgenic line, a net increase of 40% compared to wild type. These results indicate that the CrFAE gene encodes a condensing enzyme involved in the biosynthesis of very long-chain fatty acids utilizing monounsaturated and saturated acyl substrates, with a strong capability for improving the erucic acid content
Bioboxes: standardised containers for interchangeable bioinformatics software
Belmann P, Dröge J, Bremges A, McHardy AC, Sczyrba A, Barton MD. Bioboxes: standardised containers for interchangeable bioinformatics software. GigaScience. 2015;4(1): 47.Software is now both central and essential to modern biology, yet lack of availability, difficult installations, and complex user interfaces make software hard to obtain and use. Containerisation, as exemplified by the Docker platform, has the potential to solve the problems associated with sharing software. We propose bioboxes: containers with standardised interfaces to make bioinformatics software interchangeable
De la prospección sistemática al laboratorio GIS en La Canal de Navarrés
El trabajo que presentamos se ha desarrollado en el marco del proyecto NSF “The Emergence of Coupled Natural and Human Landscapes in the Western Mediterranean”, en el área comprendida por la actual comarca de La Canal de Navarres. Este espacio se convierte en uno de las áreas elegidas para un programa de recogida de datos centrado en la prospección sistemática “off site “ o “patch-based” (Barton et al. 2004; Dunnell 1992). Los datos relativos a la cultura material se combinan con la información espacial y ecológica, lo cual permite una comprensión dinámica de los mismos
A unified hyperbolic formulation for viscous fluids and elastoplastic solids
We discuss a unified flow theory which in a single system of hyperbolic
partial differential equations (PDEs) can describe the two main branches of
continuum mechanics, fluid dynamics, and solid dynamics. The fundamental
difference from the classical continuum models, such as the Navier-Stokes for
example, is that the finite length scale of the continuum particles is not
ignored but kept in the model in order to semi-explicitly describe the essence
of any flows, that is the process of continuum particles rearrangements. To
allow the continuum particle rearrangements, we admit the deformability of
particle which is described by the distortion field. The ability of media to
flow is characterized by the strain dissipation time which is a characteristic
time necessary for a continuum particle to rearrange with one of its
neighboring particles. It is shown that the continuum particle length scale is
intimately connected with the dissipation time. The governing equations are
represented by a system of first order hyperbolic PDEs with source terms
modeling the dissipation due to particle rearrangements. Numerical examples
justifying the reliability of the proposed approach are demonstrated.Comment: 6 figure
In glacial environments beyond glacial terrains: Human eco-dynamics in late Pleistocene Mediterranean Iberia
The Iberian Peninsula south of the Ebro River enjoyed one of the mildest climates of Pleistocene Europe, but still experienced significant and rapid environmental shifts caused by global climate regimes. We examine the interplay between technological, social, and land-use dynamics as culturally mediated responses to climate change outside the periglacial zone. We combine information from excavated sites across eastern and southeastern Spain with systematic survey data from an intensive study area within this larger region to examine Upper Paleolithic behavioral adaptations to the environmental shifts of the late Pleistocene (late MIS-3 through MIS-2). We define indexes that serve as proxies for land-use strategies, technological specialization, and hunting practices. Variation in these indices across space and through time provides the basis for a model of Upper Paleolithic eco-dynamics. A consistent pattern of land-use, involving inland (and possibly coastal) base-camps and near-coastal hunting zones spanned the Mediterranean facade and was sufficiently flexible and resilient to environmental change to persist throughout the late Pleistocene
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