Sebastian Ramírez - Academia.edu (original) (raw)
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Papers by Sebastian Ramírez
Catalysis Today, 2005
We synthesized and studied a series of carbon-supported PtMo catalysts with a 20% metal loading a... more We synthesized and studied a series of carbon-supported PtMo catalysts with a 20% metal loading as active phase. The analysis was made with three atomic ratios in the active phase, Pt-Mo: 1-1, 7-3 and 3-1. Samples were prepared by reducing metal precursor salts with formic acid. The materials were electrochemically characterized by cyclic voltammetry, current-sampled voltammetry, CO stripping voltammetry and electrochemical impedance spectroscopy. Physical characterizations were carried out by means of SEM-EDX and DRX. EDX analysis show that the atomic proportion between Pt and Mo is similar to the nominally proposed. DRX analysis allowed the identification of metallic Pt and different Mo oxides. The calculated average crystallite size was 4.7 nm. Electrochemical analysis revealed that the sample Pt-Mo 7:3 improves the catalytic activity of the anodic ethanol oxidation reaction, increasing the current density with low Pt loading and reducing the exchange charge resistance.
International Journal of Hydrogen Energy, 2007
... Keywords: CO stripping; Platinum; Molybdenum; Carbon-supported catalyst. Article Outline. 1. ... more ... Keywords: CO stripping; Platinum; Molybdenum; Carbon-supported catalyst. Article Outline. 1. Introduction 2. Experimental 2.1. Synthesis of platinum carbonyls 2.2. Synthesis of PtMo/C catalysts 2.3. Prepared materials 2.4. X-ray diffraction 2.5. ...
ABSTRACT In this paper we present our approach to the evaluation of multimodal applications by us... more ABSTRACT In this paper we present our approach to the evaluation of multimodal applications by using participatory design workshops. Our goal is to obtain user feedback for our design on a fundamental, conceptual level. We propose in this paper the use of design ideas ...
PLOS One, 2011
The E6 oncoprotein produced by high-risk mucosal HPV stimulates ubiquitinylation and proteasome-d... more The E6 oncoprotein produced by high-risk mucosal HPV stimulates ubiquitinylation and proteasome-dependent degradation of the tumour suppressor p53 via formation of a trimeric complex comprising E6, p53, and E6-AP. p53 is also degraded by its main cellular regulator MDM2. The main binding site of p53 to MDM2 is situated in the natively unfolded N-terminal region of p53. By contrast, the regions of p53 implicated in the degradation by viral E6 are not fully identified to date. Here we generated a series of mutations (Y103G, Y107G, T155A, T155V, T155D, L264A, L265A) targeting the central folded core domain of p53 within a region opposite to its DNA-binding site. We analysed by in vitro and in vivo assays the impact of these mutations on p53 degradation mediated by viral E6 oncoprotein. Whereas all mutants remained susceptible to MDM2-mediated degradation, several of them (Y103G, Y107G, T155D, L265A) became resistant to E6mediated degradation, confirming previous works that pointed to the core domain as an essential region for the degradation of p53. In parallel, we systematically checked the impact of the mutations on the transactivation activity of p53 as well as on the conformation of p53, analysed by Nuclear Magnetic Resonance (NMR), circular dichroism (CD), and antibody probing. These measurements suggested that the conformational integrity of the core domain is an essential parameter for the degradation of p53 by E6, while it is not essential for the degradation of p53 by MDM2. Thus, the intracellular stability of a protein may or may not rely on its biophysical stability depending on the degradation pathway taken into consideration. Citation: Bernard X, Robinson P, Nominé Y, Masson M, Charbonnier S, et al. (2011) Proteasomal Degradation of p53 by Human Papillomavirus E6 Oncoprotein Relies on the Structural Integrity of p53 Core Domain. PLoS ONE 6(10): e25981.
Bulletin of The World Health Organization, 2010
Physica A-statistical Mechanics and Its Applications, 2009
We study the efficiency of parallel tempering Monte Carlo technique for calculating true ground s... more We study the efficiency of parallel tempering Monte Carlo technique for calculating true ground states of the Edwards–Anderson spin glass model. Bimodal and Gaussian bond distributions were considered in two- and three-dimensional lattices. By a systematic analysis we find a simple formula to estimate the values of the parameters needed in the algorithm to find the GS with a fixed average probability. We also study the performance of the algorithm for single samples, quantifying the difference between samples where the GS is hard, or easy, to find. The GS energies we obtain are in good agreement with the values found in the literature. Our results show that the performance of the parallel tempering technique is comparable to more powerful heuristics developed to find the ground state of Ising spin glass systems.
Developing applications for wireless sensor networks (WSNs) can provide many challenges. Environm... more Developing applications for wireless sensor networks (WSNs) can provide many challenges. Environmental conditions have a large impact on the behavior of an application, but it may not be feasible to replicate the conditions of the deployment environment while creating the application. Furthermore, long-term deployment of monitoring applications require extensive pre-deployment analysis of such applications since the sensors cannot be accessed
Para guiar el tratamiento preventivo se utilizan distintas tablas de estimación de riesgo coronar... more Para guiar el tratamiento preventivo se utilizan distintas tablas de estimación de riesgo coronario. Por otro lado, las alteraciones de la pared arterial son una manifestación de aterosclerosis subclínica y su detección mediante ecografía puede emplearse para predecir eventos coronarios.
Astronomy & Astrophysics, 2010
Aims. The characterization of the stellar population toward young high-mass star-forming regions ... more Aims. The characterization of the stellar population toward young high-mass star-forming regions allows to constrain fundamental cluster properties like distance and age. These are essential when using high-mass clusters as probes to conduct Galactic studies. Methods. NGC 7538 is a star-forming region with an embedded stellar population only unearthed in the near-infrared (NIR). We present the first near-infrared spectro-photometric study of the candidate high-mass stellar content in NGC 7538. We obtained H and K spectra of 21 sources with both the multi-object and long-slit modes of LIRIS at the WHT, and complement these data with sub-arcsecond JHK s photometry of the region using the imaging mode of the same instrument. Results. We find a wide variety of objects within the studied stellar population of NGC 7538. Our results discriminate between a stellar population associated to the H ii region, but not contained within its extent, and several pockets of more recent star formation. We report the detection of CO bandhead emission toward several sources as well as other features indicative of a young stellar nature. We infer a spectro-photometric distance of 2.7±0.5 kpc, an age spread in the range 0.5−2.2 Myr and a total mass ∼1.7×10 3 M ⊙ for the older population.
Astronomy & Astrophysics, 2010
We present a second paper of a complete characterization of stars whose low-depth transits were d... more We present a second paper of a complete characterization of stars whose low-depth transits were discovered by the OGLE-III campaign to select the most promising candidates for spectroscopic confirmation. This paper follows a similar analysis to one previously performed in Gallardo et al. (2005, A&A, 431, 707). We present new optical and near-IR photometry and derive physical parameters such as effective temperature (Teff), distance (d), the stellar radii (R_ast), and the companion radii (Rc). We selected eight M (2800 K ≤ Teff ≤ 3850 K) or K (3850 K ≤ Teff ≤ 5150 K) stellar objects as potential candidates to host exoplanets, even though, considering the radii of their companions, only the stars OGLE-TR-61, OGLE-TR-74, OGLE-TR-123, and OGLE-TR-173 are the most promising M-type transit candidates to host planets. A confirmation of the planetary nature of any of these objects would be extremely valuable in providing a means of characterizing planets transiting M-type dwarfs with effective temperatures down to only 2900 K.
Astrophysical Journal, 2007
El maltrato vos lo hacés con el simple hecho de pensar que los nativos americanos son ignorantes,... more El maltrato vos lo hacés con el simple hecho de pensar que los nativos americanos son ignorantes, o son menos importantes a cualquier otro habitante del país. Subestimarlos. Es irrespetar su cultura, su dignidad como seres humanos, cuando su capacidad es igual o muchas veces superior a cualquier persona.
Catalysis Today, 2005
We synthesized and studied a series of carbon-supported PtMo catalysts with a 20% metal loading a... more We synthesized and studied a series of carbon-supported PtMo catalysts with a 20% metal loading as active phase. The analysis was made with three atomic ratios in the active phase, Pt-Mo: 1-1, 7-3 and 3-1. Samples were prepared by reducing metal precursor salts with formic acid. The materials were electrochemically characterized by cyclic voltammetry, current-sampled voltammetry, CO stripping voltammetry and electrochemical impedance spectroscopy. Physical characterizations were carried out by means of SEM-EDX and DRX. EDX analysis show that the atomic proportion between Pt and Mo is similar to the nominally proposed. DRX analysis allowed the identification of metallic Pt and different Mo oxides. The calculated average crystallite size was 4.7 nm. Electrochemical analysis revealed that the sample Pt-Mo 7:3 improves the catalytic activity of the anodic ethanol oxidation reaction, increasing the current density with low Pt loading and reducing the exchange charge resistance.
International Journal of Hydrogen Energy, 2007
... Keywords: CO stripping; Platinum; Molybdenum; Carbon-supported catalyst. Article Outline. 1. ... more ... Keywords: CO stripping; Platinum; Molybdenum; Carbon-supported catalyst. Article Outline. 1. Introduction 2. Experimental 2.1. Synthesis of platinum carbonyls 2.2. Synthesis of PtMo/C catalysts 2.3. Prepared materials 2.4. X-ray diffraction 2.5. ...
ABSTRACT In this paper we present our approach to the evaluation of multimodal applications by us... more ABSTRACT In this paper we present our approach to the evaluation of multimodal applications by using participatory design workshops. Our goal is to obtain user feedback for our design on a fundamental, conceptual level. We propose in this paper the use of design ideas ...
PLOS One, 2011
The E6 oncoprotein produced by high-risk mucosal HPV stimulates ubiquitinylation and proteasome-d... more The E6 oncoprotein produced by high-risk mucosal HPV stimulates ubiquitinylation and proteasome-dependent degradation of the tumour suppressor p53 via formation of a trimeric complex comprising E6, p53, and E6-AP. p53 is also degraded by its main cellular regulator MDM2. The main binding site of p53 to MDM2 is situated in the natively unfolded N-terminal region of p53. By contrast, the regions of p53 implicated in the degradation by viral E6 are not fully identified to date. Here we generated a series of mutations (Y103G, Y107G, T155A, T155V, T155D, L264A, L265A) targeting the central folded core domain of p53 within a region opposite to its DNA-binding site. We analysed by in vitro and in vivo assays the impact of these mutations on p53 degradation mediated by viral E6 oncoprotein. Whereas all mutants remained susceptible to MDM2-mediated degradation, several of them (Y103G, Y107G, T155D, L265A) became resistant to E6mediated degradation, confirming previous works that pointed to the core domain as an essential region for the degradation of p53. In parallel, we systematically checked the impact of the mutations on the transactivation activity of p53 as well as on the conformation of p53, analysed by Nuclear Magnetic Resonance (NMR), circular dichroism (CD), and antibody probing. These measurements suggested that the conformational integrity of the core domain is an essential parameter for the degradation of p53 by E6, while it is not essential for the degradation of p53 by MDM2. Thus, the intracellular stability of a protein may or may not rely on its biophysical stability depending on the degradation pathway taken into consideration. Citation: Bernard X, Robinson P, Nominé Y, Masson M, Charbonnier S, et al. (2011) Proteasomal Degradation of p53 by Human Papillomavirus E6 Oncoprotein Relies on the Structural Integrity of p53 Core Domain. PLoS ONE 6(10): e25981.
Bulletin of The World Health Organization, 2010
Physica A-statistical Mechanics and Its Applications, 2009
We study the efficiency of parallel tempering Monte Carlo technique for calculating true ground s... more We study the efficiency of parallel tempering Monte Carlo technique for calculating true ground states of the Edwards–Anderson spin glass model. Bimodal and Gaussian bond distributions were considered in two- and three-dimensional lattices. By a systematic analysis we find a simple formula to estimate the values of the parameters needed in the algorithm to find the GS with a fixed average probability. We also study the performance of the algorithm for single samples, quantifying the difference between samples where the GS is hard, or easy, to find. The GS energies we obtain are in good agreement with the values found in the literature. Our results show that the performance of the parallel tempering technique is comparable to more powerful heuristics developed to find the ground state of Ising spin glass systems.
Developing applications for wireless sensor networks (WSNs) can provide many challenges. Environm... more Developing applications for wireless sensor networks (WSNs) can provide many challenges. Environmental conditions have a large impact on the behavior of an application, but it may not be feasible to replicate the conditions of the deployment environment while creating the application. Furthermore, long-term deployment of monitoring applications require extensive pre-deployment analysis of such applications since the sensors cannot be accessed
Para guiar el tratamiento preventivo se utilizan distintas tablas de estimación de riesgo coronar... more Para guiar el tratamiento preventivo se utilizan distintas tablas de estimación de riesgo coronario. Por otro lado, las alteraciones de la pared arterial son una manifestación de aterosclerosis subclínica y su detección mediante ecografía puede emplearse para predecir eventos coronarios.
Astronomy & Astrophysics, 2010
Aims. The characterization of the stellar population toward young high-mass star-forming regions ... more Aims. The characterization of the stellar population toward young high-mass star-forming regions allows to constrain fundamental cluster properties like distance and age. These are essential when using high-mass clusters as probes to conduct Galactic studies. Methods. NGC 7538 is a star-forming region with an embedded stellar population only unearthed in the near-infrared (NIR). We present the first near-infrared spectro-photometric study of the candidate high-mass stellar content in NGC 7538. We obtained H and K spectra of 21 sources with both the multi-object and long-slit modes of LIRIS at the WHT, and complement these data with sub-arcsecond JHK s photometry of the region using the imaging mode of the same instrument. Results. We find a wide variety of objects within the studied stellar population of NGC 7538. Our results discriminate between a stellar population associated to the H ii region, but not contained within its extent, and several pockets of more recent star formation. We report the detection of CO bandhead emission toward several sources as well as other features indicative of a young stellar nature. We infer a spectro-photometric distance of 2.7±0.5 kpc, an age spread in the range 0.5−2.2 Myr and a total mass ∼1.7×10 3 M ⊙ for the older population.
Astronomy & Astrophysics, 2010
We present a second paper of a complete characterization of stars whose low-depth transits were d... more We present a second paper of a complete characterization of stars whose low-depth transits were discovered by the OGLE-III campaign to select the most promising candidates for spectroscopic confirmation. This paper follows a similar analysis to one previously performed in Gallardo et al. (2005, A&A, 431, 707). We present new optical and near-IR photometry and derive physical parameters such as effective temperature (Teff), distance (d), the stellar radii (R_ast), and the companion radii (Rc). We selected eight M (2800 K ≤ Teff ≤ 3850 K) or K (3850 K ≤ Teff ≤ 5150 K) stellar objects as potential candidates to host exoplanets, even though, considering the radii of their companions, only the stars OGLE-TR-61, OGLE-TR-74, OGLE-TR-123, and OGLE-TR-173 are the most promising M-type transit candidates to host planets. A confirmation of the planetary nature of any of these objects would be extremely valuable in providing a means of characterizing planets transiting M-type dwarfs with effective temperatures down to only 2900 K.
Astrophysical Journal, 2007
El maltrato vos lo hacés con el simple hecho de pensar que los nativos americanos son ignorantes,... more El maltrato vos lo hacés con el simple hecho de pensar que los nativos americanos son ignorantes, o son menos importantes a cualquier otro habitante del país. Subestimarlos. Es irrespetar su cultura, su dignidad como seres humanos, cuando su capacidad es igual o muchas veces superior a cualquier persona.