1,174 research outputs found
Scalar Field Dark Matter: behavior around black holes
We present the numerical evolution of a massive test scalar fields around a
Schwarzschild space-time. We proceed by using hyperboloidal slices that
approach future null infinity, which is the boundary of scalar fields, and also
demand the slices to penetrate the event horizon of the black hole. This
approach allows the scalar field to be accreted by the black hole and to escape
toward future null infinity. We track the evolution of the energy density of
the scalar field, which determines the rate at which the scalar field is being
diluted. We find polynomial decay of the energy density of the scalar field,
and use it to estimate the rate of dilution of the field in time. Our findings
imply that the energy density of the scalar field decreases even five orders of
magnitude in time scales smaller than a year. This implies that if a
supermassive black hole is the Schwarzschild solution, then scalar field dark
matter would be diluted extremely fastComment: 15 pages, 21 eps figures. Appendix added, accepted for publication in
JCA
PROCEDENCIA EN EL EXTREMO SUR DEL VALLE MEDIO DEL MAGDALENA DURANTE EL CENOZOICO: DETERMINACIONES CON BASE EN EL ANÁLISIS CUANTITATIVO DE PALEOCORRIENTES
El estudio de paleocorrientes en la sucesión cenozoica del sector sur de la cuenca del Valle Medio del Magdalena (VMM) integró dos metodologías de medición, una en superficie y la otra en subsuelo, utilizando registros dipmeter. A partir de estos resultados se obtuvo un modelo de paleocorrientes para la secuencia comprendida entre el Eoceno superior – Plioceno inferior (formaciones Esmeraldas, Mugrosa y Colorado Grupo Real y Formación Mesa). Los resultados arrojaron como principal fuente de aporte a la cuenca la ancestral Cordillera Central para la secuencia sedimentaria, excepto durante dos épocas: en el Mioceno inferior (Formación Colorado) y en el Mioceno superior (Real Superior), donde la fuente de aporte cambia de la ancestral Cordillera Central a la Cordillera Oriental. Estas variaciones en las direcciones de los paleoflujos probablemente están asociadas con los primeros pulsos de levantamiento de la Cordillera Oriental durante el Mioceno temprano y tardío. Sin embargo la abundancia de materiales ígneos y metamórficos indican que la Cordillera Central continúo su actividad, aportando material a las formaciones depositadas durante estos periodos.The paleocurrents studies in the cenozoic succession of southern area of the Middle Magdalena Valley Basin (MVB), have had integrate two measurement methodologies, one in surface and the other one in the subsurface, using dipmeter logs. From those results a paleocurrents model for the sequence between the Upper Eocene – Lower Pliocene (formations Esmeraldas, Mugrosa and Colorado, Real Group, and Mesa Formation) was obtained. The results showed as the main supply source to the basin, the ancestral Central Cordillera for the sedimentary sequence, with the exception of two epochs: Lower Miocene (Colorado Formation) and Upper Miocene (Upper Real), where the supply source changes from the ancestral Central Cordillera to the Eastern Cordillera. In the sense of the paleoflows these variations are probably associated with the first pulses of the Eastern Cordillera rise during the Early and Late Miocene. However the abundance of igneous and metamorphic materials indicates that the Central Cordillera keeps its activity, providing material to the formations deposited during those periods
PROCEDENCIA EN EL EXTREMO SUR DEL VALLE MEDIO DEL MAGDALENA DURANTE EL CENOZOICO: DETERMINACIONES CON BASE EN EL ANÁLISIS CUANTITATIVO DE PALEOCORRIENTES
El estudio de paleocorrientes en la sucesión cenozoica del sector sur de la cuenca del Valle Medio del Magdalena (VMM) integró dos metodologías de medición, una en superficie y la otra en subsuelo, utilizando registros dipmeter. A partir de estos resultados se obtuvo un modelo de paleocorrientes para la secuencia comprendida entre el Eoceno superior – Plioceno inferior (formaciones Esmeraldas, Mugrosa y Colorado Grupo Real y Formación Mesa). Los resultados arrojaron como principal fuente de aporte a la cuenca la ancestral Cordillera Central para la secuencia sedimentaria, excepto durante dos épocas: en el Mioceno inferior (Formación Colorado) y en el Mioceno superior (Real Superior), donde la fuente de aporte cambia de la ancestral Cordillera Central a la Cordillera Oriental. Estas variaciones en las direcciones de los paleoflujos probablemente están asociadas con los primeros pulsos de levantamiento de la Cordillera Oriental durante el Mioceno temprano y tardío. Sin embargo la abundancia de materiales ígneos y metamórficos indican que la Cordillera Central continúo su actividad, aportando material a las formaciones depositadas durante estos periodos.The paleocurrents studies in the cenozoic succession of southern area of the Middle Magdalena Valley Basin (MVB), have had integrate two measurement methodologies, one in surface and the other one in the subsurface, using dipmeter logs. From those results a paleocurrents model for the sequence between the Upper Eocene – Lower Pliocene (formations Esmeraldas, Mugrosa and Colorado, Real Group, and Mesa Formation) was obtained. The results showed as the main supply source to the basin, the ancestral Central Cordillera for the sedimentary sequence, with the exception of two epochs: Lower Miocene (Colorado Formation) and Upper Miocene (Upper Real), where the supply source changes from the ancestral Central Cordillera to the Eastern Cordillera. In the sense of the paleoflows these variations are probably associated with the first pulses of the Eastern Cordillera rise during the Early and Late Miocene. However the abundance of igneous and metamorphic materials indicates that the Central Cordillera keeps its activity, providing material to the formations deposited during those periods
Cutting Edge: Lessons from fraxinus, a crowd-sourced citizen science game in genomics
In 2013, in response to an epidemic of ash dieback disease in England the previous year, we launched a Facebook-based game called Fraxinus to enable non-scientists to contribute to genomics studies of the pathogen that causes the disease and the ash trees that are devastated by it. Over a period of 51 weeks players were able to match computational alignments of genetic sequences in 78% of cases, and to improve them in 15% of cases. We also found that most players were only transiently interested in the game, and that the majority of the work done was performed by a small group of dedicated players. Based on our experiences we have built a linear model for the length of time that contributors are likely to donate to a crowd-sourced citizen science project. This model could serve a guide for the design and implementation of future crowd-sourced citizen science initiatives
Factores de Crecimiento Epitelial: Aspectos Biológicos, Patológicos y Clínicos
RESUMEN Los Factores de Crecimiento son mediadores de comunicación celular con un papel vital en el comportamiento normal y patológico celular, tisular y sistémico, de los organismos vivos. Dentro de ellos la familia de los EGF(Factor de Crecimiento Epitelial) son elementos claves en la fisiología celular no sólo celular epitelial, sino también en otros tipos celulares, regulando procesos morfogénicos a varios niveles. Es el objetivo de esta revisión es describir el estado del arte de esta familia de factores de crecimiento tanto en la normalidad como en sus aspectos patológicos. Palabras Claves: Esquizofrenia, Factor de Crecimiento, EGF(Factor de Crecimiento Epitelial), Neuregulinas, Neurodegeneración, Neoplasia, Cáncer, Carcinoma ABSTRACT The growth factors are comunication cell mediators with a vital roll in the normal and pathologic comportament cell, tissue and systemic, in life organism. Into of they, the EGF(Epidermal Growth Factor) family are principal elements in the cell physiology, no only of epithelial cell, so too in others cell types, regulating morphogenic process in diverse nivels. Is the objetive of this revision to summary the corrient knowledge of this family, in the normality as in pathologic aspects. Key Words: Growth Factor, EGF(Epidermal Growth Factor), Schizophrenia, Neurodegeneration, Neuregulin, Neoplasia, Cancer, Carcinom
Factores de Crecimiento Epitelial: Aspectos Biológicos, Patológicos y Clínicos
RESUMEN Los Factores de Crecimiento son mediadores de comunicación celular con un papel vital en el comportamiento normal y patológico celular, tisular y sistémico, de los organismos vivos. Dentro de ellos la familia de los EGF(Factor de Crecimiento Epitelial) son elementos claves en la fisiología celular no sólo celular epitelial, sino también en otros tipos celulares, regulando procesos morfogénicos a varios niveles. Es el objetivo de esta revisión es describir el estado del arte de esta familia de factores de crecimiento tanto en la normalidad como en sus aspectos patológicos. Palabras Claves: Esquizofrenia, Factor de Crecimiento, EGF(Factor de Crecimiento Epitelial), Neuregulinas, Neurodegeneración, Neoplasia, Cáncer, Carcinoma ABSTRACT The growth factors are comunication cell mediators with a vital roll in the normal and pathologic comportament cell, tissue and systemic, in life organism. Into of they, the EGF(Epidermal Growth Factor) family are principal elements in the cell physiology, no only of epithelial cell, so too in others cell types, regulating morphogenic process in diverse nivels. Is the objetive of this revision to summary the corrient knowledge of this family, in the normality as in pathologic aspects. Key Words: Growth Factor, EGF(Epidermal Growth Factor), Schizophrenia, Neurodegeneration, Neuregulin, Neoplasia, Cancer, Carcinom
Novel insights into the cardio-protective effects of FGF21 in lean and obese rat hearts
Aims: Fibroblast growth factor 21 (FGF21) is a hepatic metabolic regulator with pleotropic actions. Its plasma concentrations are increased in obesity and diabetes; states associated with an increased incidence of cardiovascular disease. We therefore investigated the direct effect of FGF21 on cardio-protection in obese and lean hearts in response to ischemia.
Methods and Results: FGF21, FGF21-receptor 1 (FGFR1) and beta-Klotho (βKlotho) were expressed in rodent, human hearts and primary rat cardiomyocytes. Cardiac FGF21 was expressed and secreted (real time RT-PCR/western blot and ELISA) in an autocrine-paracrine manner, in response to obesity and hypoxia, involving FGFR1-βKlotho components. Cardiac-FGF21 expression and secretion were increased in response to global ischemia. In contrast βKlotho was reduced in obese hearts. In isolated adult rat cardiomyocytes, FGF21 activated PI3K/Akt (phosphatidylinositol 3-kinase/Akt), ERK1/2(extracellular signal-regulated kinase) and AMPK (AMP-activated protein kinase) pathways. In Langendorff perfused rat [adult male wild-type wistar] hearts, FGF21 administration induced significant cardio-protection and restoration of function following global ischemia. Inhibition of PI3K/Akt, AMPK, ERK1/2 and ROR-α (retinoic-acid receptor alpha) pathway led to significant decrease of FGF21 induced cardio-protection and restoration of cardiac function in response to global ischemia. More importantly, this cardio-protective response induced by FGF21 was reduced in obesity, although the cardiac expression profiles and circulating FGF21 levels were increased.
Conclusion: In an ex vivo Langendorff system, we show that FGF21 induced cardiac protection and restoration of cardiac function involving autocrine-paracrine pathways, with reduced effect in obesity. Collectively, our findings provide novel insights into FGF21-induced cardiac effects in obesity and ischemia
AB0629 ACCURACY OF SYNOVIAL FLUID ANALYSIS FOR THE IDENTIFICATION OF CALCIUM PYROPHOSPHATE CRYSTALS: AN ANCILLARY STUDY OF OMERACT CRITERION VALIDITY STUDY FOR ULTRASOUND IN CPPD
Accuracy of synovial fluid analysis compared to histology for the identification of calcium pyrophosphate crystals: An ancillary study of the OMERACT US working group - CPPD subgroup
The aim of this study was to evaluate the accuracy of synovial fluid analysis in the identification of calcium pyrophosphate dihydrate crystals compared to microscopic analysis of joint tissues as the reference standard. This is an ancillary study of an international, multicentre cross-sectional study performed by the calcium pyrophosphate deposition disease (CPPD) subgroup of the OMERACT Ultrasound working group. Consecutive patients with knee osteoarthritis (OA) waiting for total knee replacement surgery were enrolled in the study from 2 participating centres in Mexico and Romania. During the surgical procedures, synovial fluid, menisci and hyaline cartilage were collected and analysed within 48 hours from surgery under transmitted light microscopy and compensated polarised light microscopy for the presence/absence of calcium pyrophosphate crystals. All slides were analysed by expert examiners on site, blinded to other findings. A dichotomic score (absence/presence) was used for scoring both synovial fluid and tissues. Microscopic analysis of knee tissues was considered the gold standard. Sensitivity, specificity, accuracy, positive and negative predictive values of synovial fluid analysis in the identification of calcium pyrophosphate crystals were calculated.15 patients (53% female, mean age 68 yo +/- 8.4) with OA of grade 3 or 4 according to Kellgren-Lawrence scoring were enrolled. 12 patients (80%) were positive for calcium pyrophosphate crystals at the synovial fluid analysis and 14 (93%) at the tissue microscopic analysis. The overall diagnostic accuracy of synovial fluid analysis compared with histology for CPPD was 87%, with a sensitivity of 86% and a specificity of 100%, the positive predictive value was 100% and the negative predictive value was 33%.In conclusion synovial fluid analysis proved to be an accurate test for the identification of calcium pyrophosphate dihydrate crystals in patients with advanced OA
Menus for Feeding Black Holes
Black holes are the ultimate prisons of the Universe, regions of spacetime
where the enormous gravity prohibits matter or even light to escape to
infinity. Yet, matter falling toward the black holes may shine spectacularly,
generating the strongest source of radiation. These sources provide us with
astrophysical laboratories of extreme physical conditions that cannot be
realized on Earth. This chapter offers a review of the basic menus for feeding
matter onto black holes and discusses their observational implications.Comment: 27 pages. Accepted for publication in Space Science Reviews. Also to
appear in hard cover in the Space Sciences Series of ISSI "The Physics of
Accretion onto Black Holes" (Springer Publisher
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