725 research outputs found
Wavelength calibration of the JWST-MIRI medium resolution spectrometer
We present the wavelength and spectral resolution characterisation of the
Integral Field Unit (IFU) Medium Resolution Spectrometer for the Mid-InfraRed
Instrument (MIRI), to fly onboard the James Webb Space Telescope in 2014. We
use data collected using the Verification Model of the instrument and develop
an empirical method to calibrate properties such as wavelength range and
resolving power in a portion of the spectrometer's full spectral range (5-28
microns). We test our results against optical models to verify the system
requirements and combine them with a study of the fringing pattern in the
instrument's detector to provide a more accurate calibration. We show that
MIRI's IFU spectrometer will be able to produce spectra with a resolving power
above R=2800 in the wavelength range 6.46-7.70 microns, and that the unresolved
spectral lines are well fitted by a Gaussian profile.Comment: 12 pages, submitted to SPIE Proceedings vol. 7731, Space Telescopes
and Instrumentation 2010: Optical, Infrared, and Millimeter Wav
The AGN Luminosity Fraction in Merging Galaxies
Galaxy mergers are key events in galaxy evolution, often causing massive
starbursts and fueling active galactic nuclei (AGN). In these highly dynamic
systems, it is not yet precisely known how much starbursts and AGN respectively
contribute to the total luminosity, at what interaction stages they occur, and
how long they persist. Here we estimate the fraction of the bolometric infrared
(IR) luminosity that can be attributed to AGN by measuring and modeling the
full ultraviolet to far-infrared spectral energy distributions (SEDs) in up to
33 broad bands for 24 merging galaxies with the Code for Investigating Galaxy
Emission. In addition to a sample of 12 confirmed AGN in late-stage mergers,
found in the Revised Bright Galaxy Sample or
Faint Source Catalog, our sample includes a comparison sample of 12 galaxy
mergers from the Interacting Galaxies Survey, mostly early-stage. We
perform identical SED modeling of simulated mergers to validate our methods,
and we supplement the SED data with mid-IR spectra of diagnostic lines obtained
with InfraRed Spectrograph. The estimated AGN contributions to the IR
luminosities vary from system to system from 0% up to 91% but are significantly
greater in the later-stage, more luminous mergers, consistent with what is
known about galaxy evolution and AGN triggering.Comment: 26 pages, 10 figure
Relative Contribution of Different Upper Glycolytic Components in the Maintenance of the Retinal Vascular Endothelial Cell Barrier
Introduction: Damage to the retinal vascular endothelium is implicated in the progression of retinal degenerative diseases, including diabetic retinopathy (DR) and diabetic macular edema (DME). The retinal endothelial cells constitute the inner blood-retinal barrier (iBRB), and disruption of this barrier allows for the dysregulation of fluid and solute passage into the retina. Moreover, under normal physiological conditions, glycolytic metabolism is critical to the functioning of endothelial cells and maintenance of the iBRB. Conversely, in hyperglycemic environments, unregulated glycolytic metabolism leads to a buildup of glycolytic intermediates, which is thought to contribute to disruption of the iBRB and is associated with retinal cell damage and neovascularization. However, the metabolic mechanisms underlying these processes remain unclear. In this study, we looked to further characterize the roles of upper glycolytic enzymes, those involved in the ATP consumption phase of glycolysis, in the maintenance of the iBRB.
Methods: Electric cell-substrate impedance sensing (ECIS) technology was used to assess in real-time the role of different glycolytic enzymes in maintaining the barrier functionality of human retinal endothelial cells (HREC). Furthermore, the endothelial cellular viability was assessed through lactate dehydrogenase cytotoxicity assay following 24h, 48h, and 72h time intervals.
Results: Inhibition with heptelidic acid (glyceraldehyde-3-phosphate dehydrogenase (GA3PDH) inhibitor) significantly reduced the resistance (R) and thus the integrity of the HREC barrier at concentrations of 1.0 μM and 10 μM. PFK158 (phosphofructokinase-1 (PFK1) inhibitor) also significantly reduced R, but only at a concentration of 10 μM. Similarly, administration of PFK158 reduced HREC viability throughout all three time intervals (24h, 48h, and 72h) at a concentration of 10 μM. However, administration of heptelidic acid showed reduced HREC viability only at the 72h time interval, but also at a concentration of 10 μM. The other inhibitors tested did not demonstrate significant reduction in resistance of the HREC barrier or in cellular viability.
Conclusion: Our study demonstrates the differential roles of glycolytic enzymes in maintaining the barrier functionality of HRECs. We specifically showed that the functions of GA3PDH and PFK-1 are the most important components in regulating HREC barrier integrity. These observed differences are significant since they could serve as the basis for future pharmacological and gene expression studies aiming to improve the activity of GA3PDH and PFK1 and thereby provide avenues for therapeutic modalities in endothelial-associated retinal diseases
Evaluación histológica del efecto de enzimas con actividad depilatoria sobre piel vacuna
La industria curtidora genera una variedad de desechos potencialmente tóxicos que dependen del proceso de depilado utilizado. Para atenuar esta contaminación, se desarrollaron sistemas alternativos de depilado, entre ellos el enzimático. En la epidermis, a nivel del estrato corneo, se ubican lÃpidos que ocupan casi por completo el espacio intercelular entre los queratinocitos y desempeñan un importante papel como barrera hidrofóbica. Esta barrera debe transformarse para permitir el paso de las enzimas depilatorias hacia sus sitios de acción: folÃculo piloso/pelo y membrana basal. Las estructuras mencionadas deben eliminarse sin dañar el colágeno, proteÃna determinante de la calidad del cuero. Sobre trozos de piel bovina fueron analizados los efectos de diferentes pretratamientos tendientes a favorecer la penetración de enzimas depilatorias. Se utilizaron tensioactivos y sulfito de sodio como pretratamiento y posteriormente tratamientos con proteasas comerciales, una de origen pancréático y otra alcalina. El control fue tratado con buffer de bicarbonato de sodio. Las muestras se colorearon con Hematoxilina Eosina y Tricrómico de Masson. En los cortes sometidos a acción enzimática se encontraron cambios en el colágeno que podrÃan alterar la calidad del cuero.Se concluye que el estudio histológico de la piel permite evaluar los cambios que pueden ocasionar los tratamientos que se realizan para convertirla en cuero
The Predictive Link between Matrix and Metastasis
Cancer spread (metastasis) is responsible for 90% of cancer-related fatalities. Informing patient treatment to prevent metastasis, or kill all cancer cells in a patient\u27s body before it becomes metastatic is extremely powerful. However, aggressive treatment for all non-metastatic patients is detrimental, both for quality of life concerns, and the risk of kidney or liver-related toxicity. Knowing when and where a patient has metastatic risk could revolutionize patient treatment and care. In this review, we attempt to summarize the key work of engineers and quantitative biologists in developing strategies and model systems to predict metastasis, with a particular focus on cell interactions with the extracellular matrix (ECM), as a tool to predict metastatic risk and tropism
Estrutura populacional da abelha ibérica (Apis mellifera iberiensis) inferida por análise de morfometria geométrica em obreiras
A abelha ibérica (Apis mellifera iberiensis) é uma das subespécies de abelha melÃfera mais estudadas no mundo no que concerne aos padrões de diversidade genética. Esses estudos têm revelado resultados incongruentes e dependentes do tipo de marcador genético utilizado. No sentido de contribuirmos para uma melhor compreensão e representação dos padrões espaciais de diversidade genética da abelha ibérica e forças evolutivas subjacentes, recentemente amostramos na PenÃnsula Ibérica 711 colónias ao longo de três transectos: um na costa atlântica, um na costa mediterrânica e outro no centro. Contrariamente aos microssatélites, que são incapazes de detetar estrutura genética, os marcadores mitocondriais (região intergénica tRNAleu-cox2) e nucleares (polimorfismos de nucleótido simples, SNPs) revelaram a existência de um cline com orientação nordeste-sudoeste, padrão consistente com um processo de contacto secundário pós-glacial (Chávez-Galarza et al. 2015). No seguimento destes resultados, querÃamos testar o poder da morfometria geométrica na captura do padrão clinal previamente encontrado. Para tal, examinamos a asa anterior direita de cinco obreiras de cada uma das 711 colónias. Em cada asa foram marcados 19 pontos nas interseções das veias e, após alinhamento Procrustes, foi calculada a distância entre todos os pontos. A matriz de distâncias obtida foi usada para inferir a estrutura populacional aplicando uma análise multivariada espacial baseada na análise de componentes principais e na autocorrelaçao de Moran. Surpreendentemente, os nossos resultados mostram a presença de dois grupos com uma distribuição espacial totalmente congruente com o mtDNA e os SNPs, indicando que a morfometria geométrica é capaz de capturar padrões genéticos moldados por processos evolutivos complexos. A adição do componente geográfico nas análises multivariadas contribuiu consideravelmente para os resultados e deverá ser incorporada em futuras análises morfométricas populacionais.info:eu-repo/semantics/publishedVersio
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