59 research outputs found
Biosynthetic FGF-2 is targeted to non-lipid raft microdomains following translocation to the extracellular surface of CHO cells
No full textBasic fibroblast growth factor (FGF-2) is a secretory protein that lacks a signal peptide. Consistently, FGF-2 has been shown to be secreted by an ER-Golgi-independent mechanism; however, the machinery mediating this process remains to be established at the molecular level. Here we introduce a novel experimental system based on flow cytometry that allows the quantitative assessment of non-classical FGF-2 secretion in living cells. Stable cell lines have been created by retroviral transduction that express various kinds of FGF-2-GFP fusion proteins in a doxicyclin-dependent manner. Following induction of protein expression, biosynthetic FGF-2-GFP is shown to translocate to the outer surface of the plasma membrane as determined by both fluorescence activated cell sorting (FACS) and confocal microscopy. Both N- and C-terminal GFP tagging of FGF-2 is compatible with FGF-2 export, which is shown to occur in a controlled fashion rather than through unspecific release. The experimental system described has strong implications for the identification of both FGF-2 secretion inhibitors and molecular components involved in FGF-2 secretion. In the second part of this study we made use of the FGF-2 export system described to analyze the fate of biosynthetic FGF-2-GFP following export to the extracellular space. We find that secreted FGF-2 fusion proteins accumulate in large heparan sulfate proteoglycan (HSPG)-containing protein clusters on the extracellular surface of the plasma membrane. These microdomains are shown to be distinct from caveolae-like lipid rafts known to play a role in FGF-2-mediated signal transduction. Since CHO cells lack FGF high-affinity receptors (FGFRs), it can be concluded that FGFRs mediate the targeting of FGF-2 to lipid rafts. Consistently, FGF-2-GFP-secreting CHO cells do not exhibit increased proliferation activity. Externalization and deposition of biosynthetic FGF-2 in HSPG-containing protein clusters are independent processes, as a soluble secreted intermediate was demonstrated. The balance between intracellular FGF-2 and HSPG-bound secreted FGF-2 is shown not to be controlled by the availability of cell surface HSPGs, indicating that the FGF-2 secretion machinery itself is rate-limiting
Investigación etnográfica basada en un análisis de caso donde se observa las prácticas de enseñanza de Lengua en Tercero de Básica B, C y D en el Colegio José Engling
No full textThis degree paper is an ethnographic investigation about the education practices that
took place in a classroom corresponding to the third grade in the Language area, at the
José Engling School in the Parrish of Tumbaco, Metropolitan District of Quito.
The Ethnographic investigation was performed by the direct observation of three
classrooms corresponding to the third grade B, C and D of elementary school, and it
was developed through two investigation tools: the first one was a daily record or
diary of activities of the classes that were observed, which included all the social,
education and general aspects. The second instrument was the record card where all
the education process implemented by the teacher with her students was filed.
Within these record cards the class planning was also observed and it included the
actions of the teacher to fulfill the weekly planning for each class. I was able to verify
all the components of the planning and how the teacher executed actions or changes
as response to the student’s initiatives or the interaction with the students during the
period of learning.
As part of this investigation, I was able also to observe the procedures of the
methodologic structure of the theme presented during the learning period. And how
to execute and apply this procedure during the class work in order to reach the
objective of the learning process or the acquisition of the knowledge proposed.
The observation included the interaction between the teacher and her students and the
evaluation strategies of the theme or knowledge proposed. As part of the evaluation,
the tasks proposed to the students to reinforce the knowledge were also observed.El presente trabajo de titulación es una investigación etnográfica sobre las prácticas
pedagógicas realizadas en tercero de básica en el área de Lengua, las mismas que
tuvieron lugar en el Colegio Católico José Engling de la parroquia de Tumbaco del
Distrito Metropolitano de Quito.
La investigación etnográfica se llevó a cabo a través de la observación directa a tres
paralelos de tercero de básica, B, C y D; y se utilizaron dos instrumentos: el primero
fue un diario de campo, mantenido durante las clases observadas y en el cual se
registraron todos los acontecimientos sociales, pedagógicos o generales que se
presentaron en las clases. El segundo instrumento fueron las fichas de observación en
las cuales se verifica el trabajo realizado por el docente con sus alumnos.
Conjuntamente con las fichas de observación, se revisaron las planificaciones
realizadas por la docente para cada clase observada. Se pudieron verificar los
componentes de la planificación que pudieron ser ejecutados y aplicados en las
distintas clases así como los cambios efectuados por la docente en respuesta a los
diferentes hechos ocurridos en la clase y la interacción con los alumnos.
Como parte de este trabajo, se observaron también los procedimientos en la estructura
metodológica del tema de clase. Como se ejecuta y aplica el procedimiento dentro de
la organización del trabajo de la asignatura para avanzar en el proceso de aprendizaje
y adquisición del conocimiento.
También se observó la interacción entre la docente y los alumnos dentro de las
actividades de la asignatura y las estrategias de evaluación del tema de clase, así como
el tipo de tareas académicas que realizaban los niños en su hora de clase
www.atmos-chem-phys.net/14/8043/2014/ doi:10.5194/acp-14-8043-2014 © Author(s) 2014. CC Attribution 3.0 License. Assessing the regional impact of indonesian biomass burning emissions based on organic molecular tracers and chemical mass balance modelin
Ambient and personal PM2.5 exposure assessment in the Chinese megacity of Guangzhou
No full textJahn HJ, Krämer A, Chen X-C, Chan C-Y, Engling G, Ward TJ. Ambient and personal PM2.5 exposure assessment in the Chinese megacity of Guangzhou. Atmospheric Environment. 2013;74:402-411.Introduction: Due to the rapid economic development and the associated increase of transportation, agricultural and industrial activities, the densely populated Pearl River Delta, China has significant problems with air pollution. With a population of almost 13 million residents, the megacity of Guangzhou is of particular interest with respect to environmental health due to its large population and numerous anthropogenic and industrial sources of fine airborne particulate matter (< 2.5 mu m in aerodynamic diameter [PM2.5). Material and methods: During the winter months of November and December 2011, extensive ambient PM2.5 monitoring was simultaneously conducted within nine of 12 districts of Guangzhou. In addition, personal PM2.5 monitoring was carried out within eight of the 12 districts to determine the levels of PM2.5 to which individuals were exposed to over 24-h periods. Results: Results of the ambient monitoring showed average PM2.5 mass concentrations ranging from 52.4 +/- 24.1 (SD, standard deviation) mu g m(-3) (Median: 53.7) in the Conghua District to 106.6 +/- 31.7 mu g m(-3) (Median: 108.1) in the Yuexiu District. Results of the personal monitoring showed average concentrations ranging from 45.4 +/- 21.2 mu g m(-3) (Median: 53.1) in the Conghua District to 92.5 +/- 33.2 mu g m(-3) (Median: 102.4) in the Luogang District. Three of the districts showed moderate to high correlations between ambient and personal PM2.5 (Yuexiu: Spearman's Rho [r(s)] = 0.77, p = 0.072; Panyu: r(s) = 0.59, p = 0.033; Luogang: r(s) = 0.79, p = 0.021). Five of the seven districts had ambient PM2.5 concentrations higher than personal PM2.5 concentrations. An overall correlation analysis of all ambient and personal data shows a high and significant correlation (r(s) = 0.7, p = 0.01). Discussion: This study revealed elevated PM2.5 mass concentrations throughout all of Guangzhou's districts, with ambient PM2.5 levels that consistently exceeded the 24-h standards of both the World Health Organization and the United States Environmental Protection Agency. Results from the PM2.5 personal monitoring program also revealed elevated concentrations. Conclusions: Firstly, based on findings from previous epidemiological studies, one can conclude that this level of PM2.5 burden has strong adverse effects on the inhabitants' health. Secondly, as only three of the districts showed moderate to high correlations between ambient and personal PM2.5 (with two of them being statistically significant), it is likely that the personal monitoring results were greatly influenced by indoor sources of PM2.5. The weak correlations between the ambient PM mass and personal exposure levels underline the demand for future studies measuring personal exposure in different environments with high temporal and spatial resolution, while taking into account detailed activity analyses. (C) 2013 Elsevier Ltd. All rights reserved
Using δ 13 C of Levoglucosan As a Chemical Clock
No full textCompound specific carbon isotopic measurements (δ13C) of levoglucosan were carried out for ambient aerosol sampled during an intensive biomass burning period at different sites in Guangdong province, China. The δ13C of ambient levoglucosan was found to be noticeably heavier than the average δ13C of levoglucosan found in source C3-plant-combustion samples. To estimate the photochemical age of sampled ambient levoglucosan, back trajectory analyses were done. The origin and pathways of the probed air masses were determined, using the Lagrangian-particle-dispersion-model FLEXPART and ECMWF meteorological data. On the other hand, the isotopic hydrocarbon clock concept was applied to relate the changes in the field-measured stable carbon isotopic composition to the extent of chemical processing during transport. Comparison of the photochemical age derived using these two independent approaches shows on average good agreement, despite a substantial scatter of the individual data pairs. These analyses demonstrate that the degree of oxidative aging of particulate levoglucosan can be quantified by combining laboratory KIE studies, observed δ13C at the source and in the field, as well as back trajectory analyses. In this study, the chemical loss of levoglucosan was found to exceed 50% in one-fifth of the analyzed samples. Consequently, the use of levoglucosan as a stable molecular tracer may underestimate the contribution of biomass burning to air pollution
Detection of soil moisture and snow characteristics from Skylab
No full textThe author has identified the following significant results. The most significant result is the good response of the passive radiometers, particularly the L-band radiometer, to changing soil moisture conditions near the surface of the earth. Radiometer response was very good for the five complete data sets consisting of three passes across Texas and two passes across Kansas. When data from the five different passes were combined, the correlation between the S194 radiometric temperature and soil moisture content remained high with a value of -0.96. The performance of the S193 passive radiometer was less consistent; however, one data set gave a very high correlation of -0.95. The scatterometer response to soil moisture at incidence angles near 30 deg was not as good as for the radiometers
The characteristics of brown carbon aerosol during winter in Beijing
No full textBrown carbon (i.e., light-absorbing organic carbon, or BrC) exerts important effects on the environment and on climate in particular. Based on spectrophotometric absorption measurements on extracts of bulk aerosol samples, this study investigated the characteristics of BrC during winter in Beijing, China. Organic compounds extractable by methanol contributed approximately 85% to the organic carbon (OC) mass. Light absorption by the methanol extracts exhibited a strong wavelength dependence, with an average absorption Angstrom exponent of 7.10 (fitted between 310 and 450 nm). Normalizing the absorption coefficient (babs) measured at 365 nm to the extractable OC mass yielded an average mass absorption efficiency (MAE) of 1.45 m(2)/g for the methanol extracts. This study suggests that light absorption by BrC could be comparable with black carbon in the spectral range of near-ultraviolet light. Our results also indicate that BrC absorption and thus BrC radiative forcing could be largely underestimated when using water-soluble organic carbon (WSOC) as a surrogate for BrC. Compared to previous work relying only on WSOC, this study provides a more comprehensive understanding of BrC aerosol based on methanol extraction. (C) 2015 Elsevier Ltd. All rights reserved.National Natural Science Foundation of China [21307067, 21190054]; Tsinghua University [20131089241]; International Postdoctoral Exchange Fellowship ProgramSCI(E)[email protected]; [email protected]; [email protected]
High Wintertime PM Pollution over an Offshore Island (Kinmen) off Southeastern China: 1. An Overview.
No full text[[sponsorship]]環境變遷研究中心[[note]]已出版;[SCI];有審查制度;具代表性[[note]]http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=Drexel&SrcApp=hagerty_opac&KeyRecord=0148-0227&DestApp=JCR&RQ=IF_CAT_BOXPLO
Humidification Factors from Laboratory Studies of Fresh Smoke from Biomass Fuels
No full textMeasurements of smoke aerosol humidification factors were performed in a laboratory for different biomass fuel types and burn conditions. Two nephelometers simultaneously measured dry and humidified light scattering coefficients (bsp(dry) and bsp(RH), respectively), providing the first observations of the temporal evolution of the humidification factor (f(RH) = bsp(RH)/bsp(dry)) for fresh (minutes-old) smoke. Hygroscopic characteristics of the smoke aerosols varied with fuel type and fire conditions, with the mean f(RH) ranging from 1.01 to 1.95 for fresh minutes-old smoke for the relative humidity (RH) range of 70-94%. These f(RH) values exhibited temporal variability, with some fuels alternating from hygroscopic to nonhygroscopic within minutes. Humidograms were also obtained, demonstrating that smoke from different fuels begins to take up water at different RH values. Humidification factors for hour-old smoke ranged from 1.10 to 1.51 for RH \u3e 90%. Finally, light-absorbing carbon mass measured with a multiwavelength aethalometer demonstrated different spectral responses as a function of fuel type. These laboratory experiments demonstrate the complexity of smoke hygroscopicity from young fires and are essential for understanding the radiative effects of biomass burning in the ambient atmosphere
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