14,858 research outputs found
Gene deficiency in activating Fcγ receptors influences the macrophage phenotypic balance and reduces atherosclerosis in mice
Immunity contributes to arterial inflammation during atherosclerosis. Oxidized low-density lipoproteins induce an autoimmune response characterized by specific antibodies and immune complexes in atherosclerotic patients. We hypothesize that specific Fcγ receptors for IgG constant region participate in atherogenesis by regulating the inflammatory state of lesional macrophages. In vivo we examined the role of activating Fcγ receptors in atherosclerosis progression using bone marrow transplantation from mice deficient in γ-chain (the common signaling subunit of activating Fcγ receptors) to hyperlipidemic mice. Hematopoietic deficiency of Fcγ receptors significantly reduced atherosclerotic lesion size, which was associated with decreased number of macrophages and T lymphocytes, and increased T regulatory cell function. Lesions of Fcγ receptor deficient mice exhibited increased plaque stability, as evidenced by higher collagen and smooth muscle cell content and decreased apoptosis. These effects were independent of changes in serum lipids and antibody response to oxidized low-density lipoproteins. Activating Fcγ receptor deficiency reduced pro-inflammatory gene expression, nuclear factor-κB activity, and M1 macrophages at the lesion site, while increasing anti-inflammatory genes and M2 macrophages. The decreased inflammation in the lesions was mirrored by a reduced number of classical inflammatory monocytes in blood. In vitro, lack of activating Fcγ receptors attenuated foam cell formation, oxidative stress and pro-inflammatory gene expression, and increased M2-associated genes in murine macrophages. Our study demonstrates that activating Fcγ receptors influence the macrophage phenotypic balance in the artery wall of atherosclerotic mice and suggests that modulation of Fcγ receptor-mediated inflammatory responses could effectively suppress atherosclerosis
Validación con datos in-situ de alturas de ola obtenidas mediante radar altimétrico
Los rádares altimétricos a bordo de satélites artificiales, han sido diseñados para dar información precisa de la altura del nivel del mar, la altura de ola significante y la velocidad del viento sobre la superficie del mar. En los estudios, tanto anteriores como actuales, se observan problemas en las regiones costeras, donde las medidas del altímetro tienen menor precisión y una mayor dificultad a la hora de interpretar estos datos. Estos inconvenientes son debidos a dos factores principales. En primer lugar, la contaminación de la señal radar debido a la cercanía de la costa. En segundo lugar, inexactitudes en las correcciones de marea y troposférica húmeda. A estos problemas se añade la complejidad de la zona de estudio, al ser una región con una amplia gama de procesos hidrodinámicos con diversas escalas espacio-temporales. Tener acceso a información exacta en la costa, con las condiciones que conlleva, tiene una gran importancia debido al enorme interés económico-estratégico de la zona litoral. Este interés hace que surjan nuevas estrategias para generar productos altimétricos optimizados para tales condiciones.
Las medidas de la altura de ola significante y su variabilidad en las áreas costeras son usadas para muchos propósitos (por ejemplo, análisis del transporte de sedimento, setup de la ola y tormentas de marea), y para la validación/calibración de modelos (pronóstico de oleaje, circulación oceánica). Estas aplicaciones sirven para un amplio rango de propósitos sociales relevantes, tales como el diseño de estructuras de ingeniería en alta mar, la protección de las zonas costeras, rutas para los buques y la planificación de las operaciones en el océano. Muchos estudios se han dedicado a la validación de los datos de la altura de ola significante dados por el radar altimétrico a bordo de satélites artificiales, utilizando observaciones in-situ.
El objetivo de esta ponencia es exponer una metodología para validar los datos de altura de oleaje proporcionados por el radar altimétrico RA-2 a bordo del satélite ENVISAT, a partir de datos in-situ medidos por una boya, y su aplicación a un caso particular
Improving graph-based detection of singular events for photochemical smog agents
Recently, a set of graph-based tools have been introduced for the
identification of singular events of O3, NO2 and temperature time series, as
well as description of their dynamics. These are based on the use of the
Visibility Graphs (VG). In this work, an improvement of the original approach
is proposed, being called Upside-Down Visibility Graph (UDVG). It adds the
possibility of investigating the singular lowest episodes, instead of the
highest. Results confirm the applicability of the new method for describing the
multifractal nature of the underlying O3, NO2, and temperature. Asymmetries in
the NO2 degree distribution are observed, possibly due to the interaction with
different chemicals. Furthermore, a comparison of VG and UDVG has been
performed and the outcomes show that they describe opposite subsets of the time
series (low and high values) as expected. The combination of the results from
the two networks is proposed and evaluated, with the aim of obtaining all the
information at once. It turns out to be a more complete tool for singularity
detection in photochemical time series, which could be a valuable asset for
future research.Comment: 35 pages, 7 figure
Stairs detection with odometry-aided traversal from a wearable RGB-D camera
Stairs are one of the most common structures present in human-made scenarios, but also one of the most dangerous for those with vision problems. In this work we propose a complete method to detect, locate and parametrise stairs with a wearable RGB-D camera. Our algorithm uses the depth data to determine if the horizontal planes in the scene are valid steps of a staircase judging their dimensions and relative positions. As a result we obtain a scaled model of the staircase with the spatial location and orientation with respect to the subject. The visual odometry is also estimated to continuously recover the current position and orientation of the user while moving. This enhances the system giving the ability to come back to previously detected features and providing location awareness of the user during the climb. Simultaneously, the detection of the staircase during the traversal is used to correct the drift of the visual odometry. A comparison of results of the stair detection with other state-of-the-art algorithms was performed using public dataset. Additional experiments have also been carried out, recording our own natural scenes with a chest-mounted RGB-D camera in indoor scenarios. The algorithm is robust enough to work in real-time and even under partial occlusions of the stair
Ecology of the Mayan Cichlid, Cichlasoma urophthalmus Günther, in the Alvarado Lagoonal System, Veracruz, Mexico
The Mayan cichlid, Cichlasoma urophthalmus, has a wide distribution in southeastern Mexico where it inhabits rivers and coastal lagoons. In the Alvarado lagoonal system, Veracruz, it is distributed towards the north in Camaronera Lagoon. The Mayan cichlid shows an affinity for oligohaline to mesohaline sites with submerged vegetation, well-oxygenated, deep, and transparent water. The major abundance and biomass of this species was obtained during December to February. The diet of Mayan cichlids consists principally of plant detrital material and algae. Length-frequency distribution shows 2 size classes during both the dry and rainy seasons, corresponding to reproductive fish and young of the year; during the nortes season there is only one modal size class of fish between 60–100 mm SL. Individuals with developed gonads are found throughout the year, although most reproductive adults are found between April and December. The highest Gonadosomatic Index (GSI) values coincided with the peak in reproductive activity between May and July. The fecundity ranged from 1,556–3,348 eggs/female, and there was no relationship between female size and fecundity
One-Loop Yang-Mills Integrands from Scattering Equations
We investigate in the context of the scattering equations, how one-loop
linear propagator integrands in gauge theories can be linked to integrands with
quadratic propagators using a double forward limit. We illustrate our procedure
through examples and demonstrate how the different parts of the derived
quadratic integrand are consistent with cut-integrands derived from
four-dimensional generalized unitarity. We also comment on applications and
discuss possible further generalizations.Comment: 20 pages, 6 figures, typos corrected, added clarifications and
comments. Version to be published in PR
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