602 research outputs found
Halpha Kinematics of S4G Spiral Galaxies - III. Inner rotation curves
We present a detailed study of the shape of the innermost part of the
rotation curves of a sample of 29 nearby spiral galaxies, based on high angular
and spectral resolution kinematic Halpha Fabry-Perot observations. In
particular, we quantify the steepness of the rotation curve by measuring its
slope dRvc(0). We explore the relationship between the inner slope and several
galaxy parameters, such as stellar mass, maximum rotational velocity, central
surface brightness ({\mu}0), bar strength and bulge-to-total ratio. Even with
our limited dynamical range, we find a trend for low-mass galaxies to exhibit
shallower rotation curve inner slopes than high-mass galaxies, whereas steep
inner slopes are found exclusively in high-mass galaxies. This trend may arise
from the relationship between the total stellar mass and the mass of the bulge,
which are correlated among them. We find a correlation between the inner slope
of the rotation curve and the morphological T-type, complementary to the
scaling relation between dRvc(0) and {\mu}0 previously reported in the
literature. Although we find that the inner slope increases with the Fourier
amplitude A2 and decreases with the bar torque Qb, this may arise from the
presence of the bulge implicit in both A2 and Qb. As previously noted in the
literature, the more compact the mass in the central parts of a galaxy (more
concretely, the presence of a bulge), the steeper the inner slopes. We conclude
that the baryonic matter dominates the dynamics in the central parts of our
sample galaxies.Comment: 11 pages, 11 figures, accepted for publication in MNRA
Patchiness and Demographic Noise in Three Ecological Examples
Understanding the causes and effects of spatial aggregation is one of the
most fundamental problems in ecology. Aggregation is an emergent phenomenon
arising from the interactions between the individuals of the population, able
to sense only -at most- local densities of their cohorts. Thus, taking into
account the individual-level interactions and fluctuations is essential to
reach a correct description of the population. Classic deterministic equations
are suitable to describe some aspects of the population, but leave out features
related to the stochasticity inherent to the discreteness of the individuals.
Stochastic equations for the population do account for these
fluctuation-generated effects by means of demographic noise terms but, owing to
their complexity, they can be difficult (or, at times, impossible) to deal
with. Even when they can be written in a simple form, they are still difficult
to numerically integrate due to the presence of the "square-root" intrinsic
noise. In this paper, we discuss a simple way to add the effect of demographic
stochasticity to three classic, deterministic ecological examples where
aggregation plays an important role. We study the resulting equations using a
recently-introduced integration scheme especially devised to integrate
numerically stochastic equations with demographic noise. Aimed at scrutinizing
the ability of these stochastic examples to show aggregation, we find that the
three systems not only show patchy configurations, but also undergo a phase
transition belonging to the directed percolation universality class.Comment: 20 pages, 5 figures. To appear in J. Stat. Phy
A Heritage Science Workflow to Preserve and Narrate a Rural Archeological Landscape Using Virtual Reality: The Cerro del Castillo of Belmez and Its Surrounding Environment (Cordoba, Spain)
The main aim of this article is to present a heritage action protocol based on the application of photogrammetric and LiDAR acquisitions, a catalogue of flora and fauna, archeological research, and 3D virtualization for the integrated recovery of a rural cultural heritage site located in the Alto Guadiato Valley of Cordoba, Spain. This joint multidisciplinary action focusing on a common heritage objective has resulted in a comprehensive and innovative action: the virtualization of an 800-hectare multitemporal archeological landscape. The results may be of interest to researchers, educators, and tourism agents, or for the dissemination of scientific knowledge, among other applications. The protocol of actions implemented in the framework of this project can be replicated in sites with similar characteristics, particularly rural areas with well-preserved landscapes that have not been investigated. The main result of the project is the preservation of geomorphological features using remote sensing technologies and the creation of a virtual lookout for this historical and natural landscape (GuadiatVR), which is a very uncommon outcome within the virtualization of historical landscapes. The lookout can be downloaded from Google Play on IOS
A multiproxy study distinguishes environmental change from diagenetic alteration in the recent sedimentary record of the inner Cadiz Bay (SW Spain)
In this study, we reconstruct the recent environmental evolution of the inner Cadiz Bay using sedimentary records reaching back as far as AD 1700. We report lithological descriptions of the sediments and extensive mineralogical and geochemical analyses. An extraction technique that identifies different Fe phases provides an assessment of diagenetic alteration, which allows an estimation of the original organic matter inputs to the inner Cadiz Bay. Downcore variations in Corg/N ratios, ÎŽ13Corg and ÎŽ15N are related to changes in organic matter sources and the trophic state of the water column. The downcore records of selected trace metals (e.g. Pb, Zn and Cu) are interpreted to reflect changes in heavy metal pollution in the bay, while records of other elements (e.g. Mn and P) are likely overprinted by diagenetic alteration. Major environmental shifts took place during the 20th century, when the population around Cadiz Bay increased exponentially. Increases in sediment accumulation rates, organic matter inputs and heavy metal contents, in parallel with increases in ÎŽ13Corg and ÎŽ15N over this period, are interpreted as direct effects of the increasing anthropogenic influence in the area. The results of this study suggest that multiproxy approaches and detailed consideration of diagenetic overprinting are required to reconstruct past environmental conditions from coastal sediments
Deciphering the introduction and transmission of SARS-CoV-2 in the Colombian Amazon Basin
La pandemia del SARS-CoV-2 ha obligado a las autoridades sanitarias de todo el mundo a tomar importantes decisiones para reducir su propagaciĂłn. La epidemiologĂa genĂłmica se ha convertido en una herramienta valiosa para comprender las introducciones y la propagaciĂłn del virus en una ubicaciĂłn geogrĂĄfica especĂfica.The SARS-CoV-2 pandemic has forced health authorities across the world to take important decisions to curtail its spread. Genomic epidemiology has emerged as a valuable tool to understand introductions and spread of the virus in a specific geographic location
Rents, knowledge and neo-structuralism: transforming the productive matrix in Ecuador
This paper explores the relationship between ground rent, production and knowledge in Ecuadorâs neo-structuralist, state-led project to transform the productive matrix. Based upon insights from the Marxian approach to the critique of political economy, we interrogate how neo-structuralism has conceptualised the relationship between ânatural resource incomeâ and âknowledge-basedâ economic development. The paper argues that a rent-theoretical perspective, which takes seriously the regional unfolding of uneven geographical development in Latin America, can highlight the limits of a national development plan conceived according to the logic of Schumpeterian efficiency. In doing so, the paper identifies the contradictory relationship between natural resource exports, state-led âknowledgeâ-based development and capital accumulation. On this basis the paper offers a historically and empirically informed critical analysis of selective import substitution industrialisation and vanguard science and technology strategies designed to transition Ecuador away from primary resource dependence
The International Mouse Phenotyping Consortium (IMPC): a functional catalogue of the mammalian genome that informs conservation.
The International Mouse Phenotyping Consortium (IMPC) is building a catalogue of mammalian gene function by producing and phenotyping a knockout mouse line for every protein-coding gene. To date, the IMPC has generated and characterised 5186 mutant lines. One-third of the lines have been found to be non-viable and over 300 new mouse models of human disease have been identified thus far. While current bioinformatics efforts are focused on translating results to better understand human disease processes, IMPC data also aids understanding genetic function and processes in other species. Here we show, using gorilla genomic data, how genes essential to development in mice can be used to help assess the potentially deleterious impact of gene variants in other species. This type of analyses could be used to select optimal breeders in endangered species to maintain or increase fitness and avoid variants associated to impaired-health phenotypes or loss-of-function mutations in genes of critical importance. We also show, using selected examples from various mammal species, how IMPC data can aid in the identification of candidate genes for studying a condition of interest, deliver information about the mechanisms involved, or support predictions for the function of genes that may play a role in adaptation. With genotyping costs decreasing and the continued improvements of bioinformatics tools, the analyses we demonstrate can be routinely applied
The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in
operation since July 2014. This paper describes the second data release from
this phase, and the fourteenth from SDSS overall (making this, Data Release
Fourteen or DR14). This release makes public data taken by SDSS-IV in its first
two years of operation (July 2014-2016). Like all previous SDSS releases, DR14
is cumulative, including the most recent reductions and calibrations of all
data taken by SDSS since the first phase began operations in 2000. New in DR14
is the first public release of data from the extended Baryon Oscillation
Spectroscopic Survey (eBOSS); the first data from the second phase of the
Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2),
including stellar parameter estimates from an innovative data driven machine
learning algorithm known as "The Cannon"; and almost twice as many data cubes
from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous
release (N = 2812 in total). This paper describes the location and format of
the publicly available data from SDSS-IV surveys. We provide references to the
important technical papers describing how these data have been taken (both
targeting and observation details) and processed for scientific use. The SDSS
website (www.sdss.org) has been updated for this release, and provides links to
data downloads, as well as tutorials and examples of data use. SDSS-IV is
planning to continue to collect astronomical data until 2020, and will be
followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14
happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov
2017 (this is the "post-print" and "post-proofs" version; minor corrections
only from v1, and most of errors found in proofs corrected
A chemical survey of exoplanets with ARIEL
Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planetâs birth, and evolution. ARIEL was conceived to observe a large number (~1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25â7.8 ÎŒm spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allow us to measure atmospheric signals from the planet at levels of 10â100 part per million (ppm) relative to the star and, given the bright nature of targets, also allows more sophisticated techniques, such as eclipse mapping, to give a deeper insight into the nature of the atmosphere. These types of observations require a stable payload and satellite platform with broad, instantaneous wavelength coverage to detect many molecular species, probe the thermal structure, identify clouds and monitor the stellar activity. The wavelength range proposed covers all the expected major atmospheric gases from e.g. H2O, CO2, CH4 NH3, HCN, H2S through to the more exotic metallic compounds, such as TiO, VO, and condensed species. Simulations of ARIEL performance in conducting exoplanet surveys have been performed â using conservative estimates of mission performance and a full model of all significant noise sources in the measurement â using a list of potential ARIEL targets that incorporates the latest available exoplanet statistics. The conclusion at the end of the Phase A study, is that ARIEL â in line with the stated mission objectives â will be able to observe about 1000 exoplanets depending on the details of the adopted survey strategy, thus confirming the feasibility of the main science objectives.Peer reviewedFinal Published versio
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