Search

Este artículo se dedica a presentar el trabajo en torno al acervo documental personal del arquitecto José Vial Armstrong (1926-1983), parte del grupo fundador de la Escuela de Arquitectura de Valparaíso. Éste se basó en identificar, revisar, ordenar y clasificar casi mil documentos teóricos inéditos, que entregan nuevas aristas al trabajo individual de Vial Armstrong como el rol que cumplió al interior del colectivo. Considerando la propuesta de volver a revisar las fuentes de la arquitectura moderna según Panayotis Tournikiotis (2014). Este artículo se desarrolla en identificar cómo el estudio del acervo documental de Vial, permitiría visibilizar al autor en la historiografía de la arquitectura moderna en Chile, a la vez de comprender el rol del arquitecto al interior de la Escuela a la que perteneció y por lo tanto, revisar nuevos antecedentes sobre esta institución académica.

In the present work, the effect of smart shape-memory alloys on thermal buckling and post-buckling of monoclinic and unidirectional composite panels has been investigated. The aerodynamic pressure applied to the system was modeled using the piston theory method. The effect of thermal heating for ultrasonic flows was also estimated from the reference temperature method. The panel is modeled nonlinearly with large deformations based on Van Karmen's theory. The obtained results show that the shape-memory alloy was able to increase the critical temperature of thermal buckling. The effect of the arrangement of composite layers on increasing the thermal buckling temperature was also studied. The results show that the amount of thermal deflection is greatly reduced due to the use of this alloy. Also, in the higher temperature differences, the rate of reduction of the panel increases. In this work, the effects of thermal stress on buckling and thermal buckling in a rectangular composite panel with hinge-hinge boundary conditions were investigated. Also, the effect of shape retention alloy in controlling these two phenomena has been studied. The shape memory alloy wire was placed in martensitic mode to apply a compressive force to the panel to control the heating and aerodynamic forces after changing the phase to austenite. The governing equations of the system were extracted through the layer theory method to show the effects of in-plane displacements better. Investigations on the effect of different layers (symmetry effects and arrangement angle of composite sheets) were performed to investigate thermal buckling. According to the obtained results, the layer arrangement of plates (0.90 / 0.90), (-45.45), (30/60), and (0.90 / 90.0), respectively, had the greatest effect on raising the critical temperature of thermal buckling in dimensional ratios equal to or greater than one. This shows that the symmetry of the arrangements has a greater effect than the angle of the arrangements. Examining the buckling diagrams for the effect of a shape memory alloy, it can be concluded that by placing this alloy in the composite panel, in addition to raising the buckling temperature, this alloy has a greater effect on displacement control by increasing the temperature after the critical buckling temperature.

Abstract Background The primary aims of this study were to compare in patients with esophageal or esophagogastric junction cancers the potential of 68Ga-NODAGA-RGD PET/CT with that of 18F-FDG PET/CT regarding tumoral uptake and distribution, as well as histopathologic examination. Methods Ten 68Ga-NODAGA-RGD and ten 18F-FDG PET/CT were performed in nine prospectively included participants (1 woman; aged 58 ± 8.4 y, range 40–69 y). Maximum SUV (SUVmax) and metabolic tumor volumes (MTV) were calculated. The Mann–Whitney U test and Spearman correlation analysis (ρ) were used. Results 68Ga-NODAGA-RGD PET/CT detected positive uptake in 10 primary sites (8 for primary tumors and 2 for local relapse suspicion), 6 lymph nodes and 3 skeletal sites. 18F-FDG PET/CT detected positive uptake in the same sites but also in 16 additional lymph nodes and 1 adrenal gland. On a lesion-based analysis, SUVmax of 18F-FDG was significantly higher than those of 68Ga-NODAGA-RGD (4.9 [3.7–11.3] vs. 3.2 [2.6–4.2] g/mL, p = 0.014). Only one participant showed a higher SUVmax in an osseous metastasis with 68Ga-NODAGA-RGD as compared to 18F-FDG (6.6 vs. 3.9 g/mL). Correlation analysis showed positive correlation between 18F-FDG and 68Ga-NODAGA-RGD PET parameters (ρ = 0.56, p = 0.012 for SUVmax, ρ = 0.78, p

Este trabajo estudia el concepto de signo en el pintor Francisco Méndez y en el escultor Claudio Girola, miembros de la Escuela de Arquitectura de Valparaíso. Se ocupará de contextualizar esta práctica, entendida como un gesto plástico efímero asociado al acto poético, y se revisarán algunos ejemplos realizados por Girola en la travesía Amereida (1965) y otros liderados por Méndez en las travesías a cabo Froward (1984) y a Curamahuida (1986). Se sugerirá que el signo definió parte del quehacer individual de estos artistas: en el caso de Méndez, en la práctica de la pintura no albergada, y en el de Girola, en la diversidad material empleada. Finalmente, se propondrá la existencia de un giro sígnico que determinó una particular estética caracterizada por la emergencia y la precariedad material.

Most land surface models can, depending on the simulation experiment, calculate the vegetation distribution and dynamics internally by making use of biogeographical principles or use vegetation maps to prescribe spatial and temporal changes in vegetation distribution. Irrespective of whether vegetation dynamics are simulated or prescribed, it is not practical to represent vegetation across the globe at the species level because of its daunting diversity. This issue can be circumvented by making use of 5 to 20 plant functional types (PFTs) by assuming that all species within a single functional type show identical land–atmosphere interactions irrespective of their geographical location. In this study, we hypothesize that remote-sensing-based assessments of aboveground biomass can be used to constrain the process in which real-world vegetation is discretized in PFT maps. Remotely sensed biomass estimates for Africa were used in a Bayesian framework to estimate the probability density distributions of woody, herbaceous and bare soil fractions for the 15 land cover classes, according to the United Nations Land Cover Classification System (UN-LCCS) typology, present in Africa. Subsequently, the 2.5th and 97.5th percentiles of the probability density distributions were used to create 2.5 % and 97.5 % credible interval PFT maps. Finally, the original and constrained PFT maps were used to drive biomass and albedo simulations with the Organising Carbon and Hydrology In Dynamic Ecosystems (ORCHIDEE) model. This study demonstrates that remotely sensed biomass data can be used to better constrain the share of dense forest PFTs but that additional information on bare soil fraction is required to constrain the share of herbaceous PFTs. Even though considerable uncertainties remain, using remotely sensed biomass data enhances the objectivity and reproducibility of the process by reducing the dependency on expert knowledge and allows assessing and reporting the credible interval of the PFT maps which could be used to benchmark future developments.

Studies using arginine–glycine–aspartate (RGD)-PET agents in cardiovascular diseases have been recently published. The aim of this systematic review was to perform an updated, evidence-based summary about the role of RGD-based PET agents in patients with cardiovascular diseases to better address future research in this setting. Original articles within the field of interest reporting the role of RGD-based PET agents in patients with cardiovascular diseases were eligible for inclusion in this systematic review. A systematic literature search of PubMed/MEDLINE and Cochrane library databases was performed until October 26, 2021. Literature shows an increasing role of RGD-based PET agents in patients with cardiovascular diseases. Overall, two main topics emerged: the infarcted myocardium and atherosclerosis. The existing studies support that αvβ3 integrin expression in the infarcted myocardium is well evident in RGD PET/CT scans. RGD-based PET radiotracers accumulate at the site of infarction as early as 3 days and seem to be peaking at 1–3 weeks post myocardial infarction before decreasing, but only 1 study assessed serial changes of myocardial RGD-based PET uptake after ischemic events. RGD-based PET uptake in large vessels showed correlation with CT plaque burden, and increased signal was found in patients with prior cardiovascular events. In human atherosclerotic carotid plaques, increased PET signal was observed in stenotic compared with non-stenotic areas based on MR or CT angiography data. Histopathological analysis found a co-localization between tracer accumulation and areas of αvβ3 expression. Promising applications using RGD-based PET agents are emerging, such as prediction of remodeling processes in the infarcted myocardium or detection of active atherosclerosis, with potentially significant clinical impact.

Every spoken linguistic system shared by a community has structurally related regional variants. For example, the variant of the present day French for "soixante-dix" is "septante" in eastern France, Belgium, and the French-speaking community of Switzerland. This suggests that Proto-Romance has regionalisms. Using the comparative method, the only method for reconstructing a proto-language, presents problems, because it has been conceived for researching the reconstruction of the standard norm. The purpose of this article is to show that the existence of certain types of regionalisms may nevertheless be proven by alternative methods. (Contains 27 references and 23 notes.) (Author/VWL)

In this work, numerical study of two dimensional laminar incompressible flow around an oscillating NACA0012 airfoil is proceeded using the open source code OpenFOAM. Oscillatory motion types including pitching and flapping are considered. Reynolds number for these motions is assumed to be 12000 and effects of these motions and also different unsteady parameters such as amplitude and reduced frequency on aerodynamic coefficients are studied. For flow control on airfoil, dielectric barrier discharge plasma actuator is used in two different positions on airfoil and its effect is compared for the two types of considered oscillating motions. It is observed that in pitching motion, imposing plasma leads to an improvement in aerodynamic coefficients, but it does not have any positive effect on flapping motion. Also, for the amplitudes and frequencies investigated in this paper, the trailing edge plasma had a more desirable effect than other positions. Keywords: Airfoil, Flapping, Oscillating, Plasma, Pitching

En este artículo se estudia la presencia de una figura curatorial en el Museo a Cielo Abierto de Valparaíso. Más allá de la dimensión administrativa que le ha dado al cargo la Universidad Católica de Valparaíso, responsable del Museo, se propone que su ideólogo, el pintor, arquitecto y profesor Francisco Méndez Labbé, fue también curador del proyecto. Esto se demostraría en su interés por una relación de las obras entre sí y el vínculo entre pintura y paisaje. Para demostrarlo, revisaremos puntos clave del recorrido y documentos de archivo sobre el Museo. En específico, una serie de bocetos y un registro fotográfico nos permitirán establecer relaciones entre la propuesta de Méndez y la curaduría. Sin embargo, explicaremos que este criterio no estaba presente entre sus objetivos, y no se percató que su concepción del Museo estaba en línea con planteamientos propios de la curaduría contemporánea, como la relación con el espacio, la interacción con las obras y una propuesta de carácter experimental.

In this work, a numerical study of two dimensional laminar incompressible flow around the flexible oscillating NACA0012 airfoil is performed using the open source code OpenFOAM. Oscillatory motion types including pitching and flapping is considered. Reynolds number for these motions is assumed fixed at 12000. One of the important issues that must be considered in designing air structures, in particular the aircraft wing, is the interaction between the air and the elastic aircraft wings that is known as the Aeroelastic phenomenon. For this purpose, the effect of airfoil flexibility and flow induced vibration in these motion types is investigated and compared with the case of rigid airfoil. It is observed that the flexibility in both types of motions causes improvement of the thrust which is boosted with increasing the frequency. Contrary to thrust, the significant improvement of lift is only achievable in high frequencies. It was also found that the effect of flexibility on the flapping motion is higher than the pitching motion. For flow control on the airfoil, Dielectric Barrier Discharge plasma actuator is used in the trailing edge of a flexible airfoil, and its effect on the flexible airfoil is also investigated.

West Africa is a region in fast transition from climate, demography, and land use perspectives. In this context, the African Monsoon Multidisciplinary Analysis (AMMA)–Couplage de l’Atmosphère Tropicale et du Cycle eco-Hydrologique (CATCH) long-term regional observatory was developed to monitor the impacts of global change on the critical zone of West Africa and to better understand its current and future dynamics. The observatory is organized into three thematic axes, which drive the observation and instrumentation strategy: (i) analyze the long-term evolution of eco-hydrosystems from a regional perspective; (ii) better understand critical zone processes and their variability; and (iii) meet socioeconomic and development needs. To achieve these goals, the observatory has gathered data since 1990 from four densely instrumented mesoscale sites (∼10 km each), located at different latitudes (Benin, Niger, Mali, and Senegal) so as to sample the sharp eco-climatic gradient that is characteristic of the region. Simultaneous monitoring of the vegetation cover and of various components of the water balance at these four sites has provided new insights into the seemingly paradoxical eco-hydrological changes observed in the Sahel during the last decades: groundwater recharge and/or runoff intensification despite rainfall deficit and subsequent re-greening with still increasing runoff. Hydrological processes and the role of certain key landscape features are highlighted, as well as the importance of an appropriate description of soil and subsoil characteristics. Applications of these scientific results for sustainable development issues are proposed. Finally, detecting and attributing eco-hydrological changes and identifying possible regime shifts in the hydrologic cycle are the next challenges that need to be faced.

18F-FBB PET is a neuroimaging modality that is been increasingly used to assess brain amyloid deposits in potential patients with Alzheimer's disease (AD). In this work, we analyze the usefulness of these data to distinguish between AD and non-AD patients. A dataset with 18F-FBB PET brain images from 94 subjects diagnosed with AD and other disorders was evaluated by means of multiple analyses based on t-test, ANOVA, Fisher Discriminant Analysis and Support Vector Machine (SVM) classification. In addition, we propose to calculate amyloid standardized uptake values (SUVs) using only gray-matter voxels, which can be estimated using Computed Tomography (CT) images. This approach allows assessing potential brain amyloid deposits along with the gray matter loss and takes advantage of the structural information provided by most of the scanners used for PET examination, which allow simultaneous PET and CT data acquisition. The results obtained in this work suggest that SUVs calculated according to the proposed method allow AD and non-AD subjects to be more accurately differentiated than using SUVs calculated with standard approaches.

A semi-analytical method is used to illustrate the behavior of a multimodal nonlinear electromechanical system which is under base-excitation. System is considered as piezo-ceramic patches attached to a cantilever beam coupled to a resistive load. The cantilever beam is modeled as a nonlinear Timoshenko beam using Assumed Mode method and equations of motion are derived through Lagrange's equation. Nonlinear multimodal equations are solved with Complexification Averaging method and results are compared with numerical simulations. Arc length Continuation method is used to achieve frequency response of the system. Results are presented for different values of geometric and physical parameters and the effect of this variations are discussed.

In the current study, behavior of crank-slider mechanism with single and multiple clearance joints are analyzed. Using Lankarani-Nikravesh theory for estimating discontinuous contact forces in clearance joints, relevant systems have been mathematically modeled. Through numerical simulations, perturbations in response of mechanisms with clearance joints have been analyzed. Effects of increasing number of clearance joints have been addressed. From comparisons between responses of crank-slider mechanism with a single clearance joint and multiple clearance joints, it is concluded that perturbations intensify as the number of clearance joints in mechanism increases. Nonlinear dynamics of system are analyzed, using Poincare maps and bifurcation diagrams. Effects of joint friction on the response of the mechanism are investigated. Subsequently, a control scheme for providing continuous contact in clearance joints and maintaining a more stable mechanism is pro-posed. Obtained results demonstrate the effectiveness of proposed control method on reducing effect's of clearance and maintaining continuous contact in clearance joint

Light and water use by vegetation at the ecosystem level, are key components for understanding the carbon and water cycles particularly in regions with high climate variability and dry climates such as Africa. The objective of this study is to examine recent trends over the last 30 years in Light Use Efficiency (LUE) and inherent Water Use Efficiency (iWUE*) for the major biomes of Africa, including their sensitivities to climate and CO2. LUE and iWUE* trends are analyzed using a combination of NOAA-AVHRR NDVI3g and fAPAR3g, and a data-driven model of monthly evapotranspiration and Gross Primary Productivity (based on flux tower measurements and remote sensing fAPAR, yet with no flux tower data in Africa) and the ORCHIDEE (ORganizing Carbon and Hydrology In Dynamic EcosystEms) process-based land surface model driven by variable CO2 and two different gridded climate fields. The iWUE* data product increases by 10%–20% per decade during the 1982–2010 period over the northern savannas (due to positive trend of vegetation productivity) and the central African forest (due to positive trend of vapor pressure deficit). In contrast to the iWUE*, the LUE trends are not statistically significant. The process-based model simulations only show a positive linear trend in iWUE* and LUE over the central African forest. Additionally, factorial model simulations were conducted to attribute trends in iWUE and LUE to climate change and rising CO2 concentrations. We found that the increase of atmospheric CO2 by 52.8 ppm during the period of study explains 30%–50% of the increase in iWUE* and >90% of the LUE trend over the central African forest. The modeled iWUE* trend exhibits a high sensitivity to the climate forcing and environmental conditions, whereas the LUE trend has a smaller sensitivity to the selected climate forcing.

Rain Use Efficiency (RUE), defined as Aboveground Net Primary Production (ANPP) divided by rainfall, is increasingly used to diagnose land degradation. Yet, the outcome of RUE monitoring has been much debated since opposite results were found about land degradation in the Sahel region. The debate is fueled by methodological issues, especially when using satellite remote sensing data to estimate ANPP, and by differences in the ecological interpretation. An alternative method which solves part of these issues relies on the residuals of ANPP regressed against rainfall (“ANPP residuals”). In this paper, we use long-term field observations of herbaceous vegetation mass collected in the Gourma region in Mali together with remote sensing data (GIMMS-3g Normalized Difference Vegetation Index) to estimate ANPP, RUE, and the ANPP residuals, over the period 1984–2010. The residuals as well as RUE do not reveal any trend over time over the Gourma region, implying that vegetation is resilient over that period, when data are aggregated at the Gourma scale. We find no conflict between field-derived and satellite-derived results in terms of trends. The nature (linearity) of the ANPP/rainfall relationship is investigated and is found to have no impact on the RUE and residuals interpretation. However, at odds with a stable RUE, an increased run-off coefficient has been observed in the area over the same period, pointing towards land degradation. The divergence of these two indicators of ecosystem resilience (stable RUE) and land degradation (increasing run-off coefficient) is referred to as the “second Sahelian paradox”. When shallow soils and deep soils are examined separately, high resilience is diagnosed on the deep soil sites. However, some of the shallow soils show signs of degradation, being characterized by decreasing vegetation cover and increasing run-off coefficient. Such results show that contrasted changes may co-exist within a region where a strong overall re-greening pattern is observed, highlighting that both the scale of observations and the scale of the processes have to be considered when performing assessments of vegetation changes and land degradation.

El artículo trata sobre la agencia individual y colectiva de los detenidos en el sistema carcelario colombiano. A partir del 2000, las autoridades colombianas, con el apoyo de la Oficina Federal de Prisiones de EE.UU, emprendieron una reforma del sistema carcelario, llamada Nueva Cultura Penitenciaria, una política que se llevó a cabo en el marco del Plan Colombia, el programa antinarcótico y anti-insurgencia de Estados Unidos para este país. La implantación de la Nueva Cultura Penitenciaria complementó la dureza de las políticas penales y las prácticas represivas, que se venían impulsando en Colombia desde la mitad de los años 90’s. De forma similar a la mayoría de los procesos de transferencia de políticas, las características locales de la región receptora juegan un papel clave para entender como el modelo exógeno está introducido en un nuevo contexto. Este artículo plantea que el modelo carcelario estadounidense entró en conflicto con las prácticas y las representaciones arraigadas en la antigua cultura carcelaria en Colombia. Se argumenta que una de las principales resistencias que ha enfrentado el modelo estadounidense ha sido las costumbres heredadas de esta antigua cultura carcelaria, la cual está marcada por una larga historia de contestación social por parte de los detenidos y por la creatividad de sus técnicas cotidianas de supervivencia. En línea con otros autores que consideran que el análisis de la prisión debe poner mayor énfasis en la agencia de los prisioneros, este artículo se enfoca en la resistencia diaria de baja intensidad que ellos desplieguen.

Durante su primera estadía en París (1910-1914), el pintor ruso Marc Chagall conoció, principalmente en el museo del Louvre, a los maestros de la pintura occidental, tal como registró en Mi vida, su autobiografía. El caso aquí estudiado, la influencia del artista italiano Paolo Caliari en el trabajo del ruso, revela que aunque la historiografía ha pasado por alto las citas a artistas presentes en Mi vida, su lectura a la luz del concepto de tradición de Ernst Gombrich demuestra la importancia que el ruso le otorgó a las obras que conoció en la capital francesa, proponiendo una visión alternativa a la idea de artista rebelde y vanguardista que durante el siglo XX se elaboró en torno a la figura de Chagall.

For several decades, molecular recognition has been considered one of the most fundamental processes in biochemistry. For enzymes, substrate binding is often coupled to conformational changes that alter the local environment of the active site to align the reactive groups for efficient catalysis and to reach the transition state. Adaptive substrate recognition is a well-known concept; however, it has been poorly characterized at a structural level because of its dynamic nature. Here, we provide a detailed mechanism for an induced-fit process at atomic resolution. We take advantage of a slow, tight binding inhibitor-enzyme system, actinonin-peptide deformylase. Crystal structures of the initial open state and final closed state were solved, as well as those of several intermediate mimics captured during the process. Ligand-induced reshaping of a hydrophobic pocket drives closure of the active site, which is finally "zipped up" by additional binding interactions. Together with biochemical analyses, these data allow a coherent reconstruction of the sequence of events leading from the encounter complex to the key-lock binding state of the enzyme. A "movie" that reconstructs this entire process can be further extrapolated to catalysis.