325 research outputs found
Persistence of Zika Virus in Body Fluids — Final Report
Zika Virus; Body FluidsVirus Zika; Fluids corporalsFluidos corporalesPaz-Bailey and colleagues (Sept. 27 issue)1 describe the dynamics of Zika virus (ZIKV) in body fluids in a cohort of participants who lived in an area where the virus was endemic and in whom ZIKV infection was detected on reverse-transcriptase–polymerase-chain-reaction assay. We are concerned about the external validity of these results
Paleoecología del género Anchitherium von Meyer, 1834 (Equidae, Perissodactyla, Mammalia) en España: evidencias a partir de las faunas de macromamíferos
En el presente trabajo se interpreta la paleoecología y evolución del équido Anchitherium VON MEYER, 1834 por medio del análisis multifactorial (análisis de componentes principales, análisis discriminante) de las faunas de macromamíferos del Rambliense-Vallesiense inferior de la Península Ibérica. El análisis conjunto con faunas tropicales y subtropicales actuales permite inferir algunas de las características ambientales (temperatura, estacionalidad térmica) bajo las cuales se desarrollan dichas comunidades del Mioceno. Los resultados obtenidos también muestran la posibilidad de interpretar el bioma de una localidad en función de su fauna de macromamíferos, pudiéndose inferir la presencia en el Mioceno ibérico de laurisilvas, bosques tropicales y sabanas. Se observa una relación entre el tamaño relativo de la dentición respecto al tamaño corporal de Anchitherium y las variaciones en la temperatura. Las poblaciones que ocupaban ambientes térmicamente más estacionales presentaban una dentición relativamente mayor respecto al tamaño corporal que las habitantes de ambientes menos estacionales. Esto podría estar relacionado con un menor consumo de frutos determinado por una disminución en la disponibilidad
anual de los mismos en las zonas con mayor estacionalidad térmica y un aumento en el consumo de follaje, menos nutritivo. La abundancia relativa de Anchitherium en los yacimientos parece determinada principalmente por las condiciones de temperatura, siendo más abundante cuanto menor es esta. Este hecho podría estar relacionado con las condiciones ambientales que los Anchitheriinae tuvieron que superar para atravesar Beringia antes de alcanzar Eurasia. Se estudian los biomas ocupados por cada especie de Anchitherium. Los dos clados propuestos por SÁNCHEZ et al. (1998) muestran un comportamiento similar. Especies más o menos ubiquistas y adaptadas a ambientes forestales densos dan lugar a especies más derivadas y adaptadas en mayor medida a los ambientes con una estación seca (bosques tropicales y sabanas), predominantes en la Península Ibérica durante el período estudiado. Este proceso es más acusado en el segundo linaje que en el primero. Durante la zona MN 6, una especie ubiquista, el inmigrante norteño A. hippoides entra en la península y sustituye a las especies
presentes hasta el momento. Este proceso se relaciona con un progresivo aumento de la humedad ambiental que provocaría una reorganización de la fauna. Finalmente se expone un escenario ambiental para la evolución de Anchitherium en España. En él se muestra la relación de alternancia existente entre Equidae y Rhinocerotidae como grupo faunístico dominante durante el Mioceno.
[ABSTRACT]
The paleoecology and evolution of the equid Anchitherium VON MEYER, 1834 is studied in this paper by means of multifactorial analysis (principal components analysis, discriminant analysis) of the Ramblian-lower Vallesian large mammal faunas from the Iberian Peninsula. Joint analysis of subtropical and tropical recent faunas and Miocene faunas allow the establishment of several environmental characteristics (temperature, thermal seasonality) of the ecosystems of those Miocene communities. Our results indicate that it is possible to infer the biome of a locality based on its macromammal fauna. It has been able to infer the presence in the Iberian Miocene of temperate evergreen forests, tropical deciduous forests and savannas. A relationship is observed between the relative size of the dentition regarding the corporal size in Anchitherium and the temperature variations. Populations that occupied more thermally seasonal environments presented a relatively bigger dentition regarding their corporal size than the non-seasonally environment inhabitants. This could be related with a diminished consumption of fruits caused by a lesser fruit availability in the more thermal seasonality areas, and a higher consumption of leaves, less nutritive than fruits. The relative abundance of Anchitherium in the fossil local faunas seems mainly settled by temperature, being more abundant in faunas from colder fossil sites. This fact could be related with the environmental conditions
that Anchitheriinae had to overcome to cross Beringia before reaching Eurasia. Biomes occupied by each Anchitherium species are studied. The two clades proposed by SÁNCHEZ et al. (1998) shown a similar behaviour. More or less ubiquitous species, adapted to dense forest environments, are substituted by more derived species adapted to ecosystems with a dry station (tropical deciduous forests and savannas), the predominant biomes in the Iberian Peninsula during the studied period. This process is more pronounced in the second lineage than in the first one. Another ubiquitous species, the northern immigrant A. hippoides come into the Iberian Peninsula in MN 6 zone and replace the rest of species. This process is related with the progressive increment in environmental humidity causing a faunal reorganization. Finally an environmental scenario for the evolution of Anchitherium in Spain is exposed. An alternation relationship as faunal dominant group during the Miocene between Equidae and Rhinocerotidae is shown
Semejanza externa vs. semejanza sinapomórfica: el caso de Palaeomerycidae y Dromomerycidae (Cetartiodactyla, Ruminantia, Pecora)
Comunicación presentada en el XIII Encuentro en Jóvenes Investigadores en Paleontología (XIII EJIP) - XIII Meeting of Early-Stage Researchers in Paleontology (XIII EJIP): Cercedilla, 15 - 18 de Abril de 2015Peer reviewe
String Instabilities in Black Hole Spacetimes
We study the emergence of string instabilities in - dimensional black
hole spacetimes (Schwarzschild and Reissner - Nordstr\o m), and De Sitter space
(in static coordinates to allow a better comparison with the black hole case).
We solve the first order string fluctuations around the center of mass motion
at spatial infinity, near the horizon and at the spacetime singularity. We find
that the time components are always well behaved in the three regions and in
the three backgrounds. The radial components are {\it unstable}: imaginary
frequencies develop in the oscillatory modes near the horizon, and the
evolution is like , , near the spacetime
singularity, , where the world - sheet time , and the
proper string length grows infinitely. In the Schwarzschild black hole, the
angular components are always well - behaved, while in the Reissner - Nordstr\o
m case they develop instabilities inside the horizon, near where the
repulsive effects of the charge dominate over those of the mass. In general,
whenever large enough repulsive effects in the gravitational background are
present, string instabilities develop. In De Sitter space, all the spatial
components exhibit instability. The infalling of the string to the black hole
singularity is like the motion of a particle in a potential
where depends on the spacetime
dimensions and string angular momentum, with for Schwarzschild and
for Reissner - Nordstr\o m black holes. For the
string ends trapped by the black hole singularity.Comment: 26pages, Plain Te
Diásporas y transiciones en la Teoría del Actor-Red
Este texto es una presentación del monográfico Diásporas y transiciones en la teoría del actor-red. Sus páginas presentan las principales características de esta teoría, una manera de entender sus orígenes y una descripción de su presente estableciendo un paralelismo con la etnometodología. El texto finaliza con una valoración del estado de la teoría del actor-red en España y un comentario sobre un congreso que llevó el título de Presente y futuro de la teoría del actor-red y que constituye el embrión del presente monográfico. En el texto se defiende una tesis muy simple: la teoría del actor-red nace con cierta relevancia para el pensamiento social en el momento en que se difracta en una miríada de usos y aplicaciones diferentes. El principal corolario de este hecho también es muy sencillo: la gran diferencia entre la teoría del actor-red y otras propuestas del pensamiento social es su permanente estado de diáspora y transiciónThis paper is an introduction to the monograph titled Diasporas and Transitions in the Actor-Network Theory. Drawing a parallel with ethnomethodology, its pages present the main features of this theory, a way to figure out its origins and a description of its present. The text ends with a brief look at the state of art of actor-network theory in Spain and an appraisal of a meeting titled Present and Future of Actor-Network Theory, which is the origin of our monograph. In this paper we put forward a very simple idea: Actor-Network Theory was born with certain relevance in Social Sciences when it diffracted in a myriad of different uses and applications. The main corollary of such an idea is also straightforward: the very difference between Actor- Network Theory and other perspectives in Social Sciences resides in the permanent diaspora and transition of the forme
A retrospective study on the influence of siblings' relatedness in Bolivian patients with chronic Chagas disease
Brotherhood; Cardiomyopathy; Chagas diseaseGermandat; Cardiomiopatia; Malaltia de chagasHermandad; Cardiomiopatía; Enfermedad de chagasBACKGROUND:
Chagas disease is a protozoan infection caused by Trypanosoma cruzi. The disease has a chronic course in which 20-30% of the patients would develop progressive damage to the cardiovascular system and the gastrointestinal tube. We are still unable to predict who will develop end-organ damage but there are some acquired and genetic risk factors already known.
RESULTS:
We reviewed data from 833 patients with serologically confirmed Chagas disease in this retrospective study. Patients were classified as siblings or non-siblings (controls) and the results of pre-treatment blood PCR assay, end-organ damage (cardiac and/or gastrointestinal), and the presence of delayed type hypersensitivity (DTH) skin involvement in patients treated with benznidazole were analyzed. Siblings were grouped by family and we randomly generated groups of 2 or 3 persons with the remaining controls. We classified the results of each variable as concordant or discordant and compared the concordance in these results among the sibling groups with that among control groups. We identified 71 groups of siblings and randomly generated 299 groups of non-related patients. Pre-treatment blood PCR concordance was significantly higher (19%) among siblings compared to controls (P = 0.02), probably due to a higher frequency in pre-treatment positive results. No other statistically significant differences were found.
CONCLUSIONS:
A significant difference was found in the concordance of pre-treatment blood PCR for T. cruzi among siblings compared to non-related controls
Pressure Support in Galaxy Disks: Impact on Rotation Curves and Dark Matter Density Profiles
Rotation curves constrain a galaxy's underlying mass density profile, under
the assumption that the observed rotation produces a centripetal force that
exactly balances the inward force of gravity. However, most rotation curves are
measured using emission lines from gas, which can experience additional forces
due to pressure. In realistic galaxy disks, the gas pressure declines with
radius, providing additional radial support to the disk. The measured
tangential rotation speed will therefore tend to lag the true circular velocity
of a test particle. The gas pressure is dominated by turbulence, and we
evaluate its likely amplitude from recent estimates of the gas velocity
dispersion and surface density. We show that where the amplitude of the
rotation curve is comparable to the characteristic velocities of the
interstellar turbulence, pressure support may lead to underestimates of the
mass density of the underlying dark matter halo and the inner slope of its
density profile. These effects may be significant for galaxies with rotation
speeds <75km/s, but are unlikely to be significant in higher mass galaxies. We
find that pressure support can be sustained over long timescales, because any
reduction in support due to the conversion of gas into stars is compensated for
by an inward flow of gas. However, we point to many uncertainties in assessing
the importance of pressure support in galaxies. Thus, while pressure support
may alleviate possible tensions between rotation curve observations and
LambdaCDM on kiloparsec scales, it should not be viewed as a definitive
solution at this time.Comment: Accepted to the Astrophysical Journal; 18 pages including 5 pages of
figure
The fossil vertebrates from Somosaguas (Pozuelo, Madrid, Spain)
[ES] Dos yacimientos de vertebrados, situados en el Campus de Somosaguas de la Universidad Complutense (Pozuelo de Alarcón, Madrid), han proporcionado unos 600 restos identificables en estados de conservación muy variados, pertenecientes a unas veinte especies de tamaños muy diversos, desde mastodontes a musarañas. Su estudio permite fechar su edad en unos 14 m.a. y reconstruir un periodo árido en la cuenca de Madrid, ocupada durante el Mioceno medio por bosques y sabanas subtropicales con fuertes avenidas y sin ríos permanentes. En estos yacimientos se puede realizar una enseñanza práctica de la Paleontología de Vertebrados, para formación de estudiantes universitarios en el estudio y la gestión del Patrimonio Paleontológico.[EN] Two vertebrate fossil sites, situated in the Universidad Complutense Campus of Somosaguas, (Pozuelo de Alarcón, Madrid, Spain) have yielded about 600 identifiable rests in different preservation states, belonging to about twenty species of highly diverse sizes, from mastodons to shrews. Their study allows dating at about 14 m.y., and reconstructing an arid climate epoch in the Madrid basin during middle Miocene times, occupied by subtropical woodlands and savannahs with strong floods and without permanent rivers. These fossil sites allow practical teaching of Vertebrate Palaeontology, and preparing university students in the Palaeontological Heritage study and management.Hemos recibido financiación y personal respaldo del Rectorado
de la Universidad Complutense de Madrid, de los Decanatos de la
Facultad de Ciencias Políticas y Sociología y de la Facultad de Ciencias
Geológicas, y del Departamento de Paleontología de esta Facultad. El Departamento
de Paleobiología del Museo Nacional de Ciencias Naturales (CSIC)
realiza su investigación en el marco del Convenio de Colaboración con la Comunidad de Madrid a través de la Dirección General de Patrimonio Histórico
Artístico de la Consejería de Educación.Peer reviewe
Sampling Theorem and Discrete Fourier Transform on the Riemann Sphere
Using coherent-state techniques, we prove a sampling theorem for Majorana's
(holomorphic) functions on the Riemann sphere and we provide an exact
reconstruction formula as a convolution product of samples and a given
reconstruction kernel (a sinc-type function). We also discuss the effect of
over- and under-sampling. Sample points are roots of unity, a fact which allows
explicit inversion formulas for resolution and overlapping kernel operators
through the theory of Circulant Matrices and Rectangular Fourier Matrices. The
case of band-limited functions on the Riemann sphere, with spins up to , is
also considered. The connection with the standard Euler angle picture, in terms
of spherical harmonics, is established through a discrete Bargmann transform.Comment: 26 latex pages. Final version published in J. Fourier Anal. App
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