Machine-learning-based estimation of room acoustic parameters

Traditional methods to study sound propagation inside rooms can be divided in two approaches: geometrical models and wave-based models. In the former, sound is analyzed as rays, giving a valid approximation for high frequencies while failing to model certain wave effects such as diffraction or inference. The latter, finds solutions for the wave equation, providing better accuracy at the cost of much higher computational complexity. This thesis presents a proof of concept for a novel machine learning method to estimate a set of typical room acoustics parameters using only geometrical information as input features. First, a room acoustics dataset composed of real world acoustical measurements is analyzed and processed using microphone array encoding techniques to extract room impulse responses and acoustical absorption area for multiple directions. The dataset is explored to identify correlation between features and general properties, including a low dimensionality representation for visualization. The proposed method uses geometrical features as input for a neural network model that estimates room acoustics parameters, such as reverberation time (T60), and early decay time (EDT). For reverberation time, this model is evaluated against the Sabine method and the results show much higher accuracy, especially at low frequencies. The method is then expanded to include input features for the locations of the source and microphone, where the results also achieve high performance. Furthermore, an hyperparameter optimization procedure using random search reveals three main findings. First, that a large range of neural networks architectures, even with very few trainable parameters, achieve high performance. Second, the depth of the models has little influence on the results. Third, the benefit of increasing the amount of training data examples for a single loudspeaker saturates after around 100 examples

Eficacia del proceso de participación ciudadana y su impacto en el conflicto social en el distrito de Puinahua, Loreto, 2020

El presente trabajo de investigación tuvo como objetivo determinar cuál es la eficacia del proceso de participación ciudadana y cómo impacta en el conflicto social en el distrito referido. Para lograr este propósito se empleó metodología del tipo básica, de enfoque cualitativo y de diseño no experimental. Se aplicaron, sobre las categorías de investigación “participación ciudadana” y “conflicto ambiental” la técnica del análisis documental registrándola en instrumentos como la guía de análisis y las fichas. La muestra estuvo compuesta de nueve artículos científicos, tres legislaciones y dos informes de la Defensoría del Pueblo sobre los actores sociales presente en el conflicto investigado. Los resultados muestran que la eficacia y el impacto social de la participación ciudadana antes y durante el desarrollo del proyecto de hidrocarburos es mínima, al ser las entidades de la administración pública, así como las organizaciones empresariales percibidas con desconfianza por la población local. Se llegó a la conclusión de que el cambio de una actuación reactiva hacia una proactiva, tanto en mesas de capacitación, diálogo o de trabajo, como en el aislamiento de motivaciones políticas anti empresariales, lograrán un mejor tratamiento de los conflictos sociales

SLC30A3 (ZnT3) Oligomerization by Dityrosine Bonds Regulates Its Subcellular Localization and Metal Transport Capacity

Non-covalent and covalent homo-oligomerization of membrane proteins regulates their subcellular localization and function. Here, we described a novel oligomerization mechanism affecting solute carrier family 30 member 3/zinc transporter 3 (SLC30A3/ZnT3). Oligomerization was mediated by intermolecular covalent dityrosine bonds. Using mutagenized ZnT3 expressed in PC12 cells, we identified two critical tyrosine residues necessary for dityrosine-mediated ZnT3 oligomerization. ZnT3 carrying the Y372F mutation prevented ZnT3 oligomerization, decreased ZnT3 targeting to synaptic-like microvesicles (SLMVs), and decreased resistance to zinc toxicity. Strikingly, ZnT3 harboring the Y357F mutation behaved as a “gain-of-function” mutant as it displayed increased ZnT3 oligomerization, targeting to SLMVs, and increased resistance to zinc toxicity. Single and double tyrosine ZnT3 mutants indicate that the predominant dimeric species is formed between tyrosine 357 and 372. ZnT3 tyrosine dimerization was detected under normal conditions and it was enhanced by oxidative stress. Covalent species were also detected in other SLC30A zinc transporters localized in different subcellular compartments. These results indicate that covalent tyrosine dimerization of a SLC30A family member modulates its subcellular localization and zinc transport capacity. We propose that dityrosine-dependent membrane protein oligomerization may regulate the function of diverse membrane protein in normal and disease states

Analysis of friction coefficient for a base steel 5 % Cr, applying variable loads of 196 N, 294 N and 392 N, and speeds of 0,18 m/sec, 0,36 m/sec and 0,54 m/sec

The present study consists in analyzing the friction coefficient as a variable of the normal load and slip speed for 5% Cr steel, by applying the Block-on-Disk method according to ASTM D2714. The friction coefficient increases linearly 23,25 % from 0,214 to 0,266 when the load is increased from 196 N to 392 N; the same phenomenon is observed when the friction coefficient increases 47,82 % from 0,23 to 0,34 when the slip speed increases from 0,18 m/sec to 0,54 m/sec. The friction coefficient increased by 23,25 % for an increase in the load from 196 N to 392 N, which corresponds to 100 %, while an increase of the friction coefficient of 47,82 % occurred by increasing the speed from 0,18 m/sec to 0,54 m/sec which corresponds to 200 %

Extracellular Vesicles of Hypoxic Adipocytes and Obese Subjects Reduce Insulin-stimulated Glucose Uptake

Scope We investigate the effects of extracellular vesicles (EVs) obtained from in vitro adipocyte cell models and from obese subjects on glucose transport and insulin responsiveness. Methods and results EVs are isolated from the culture supernatant of adipocytes cultured under normoxia, hypoxia (1% oxygen), or exposed to macrophage conditioned media (15% v/v). EVs are isolated from the plasma of lean individuals and subjects with obesity. Cultured adipocytes are incubated with EVs and activation of insulin signalling cascades and insulin‐stimulated glucose transport are measured. EVs released from hypoxic adipocytes impair insulin‐stimulated 2‐deoxyglucose uptake and reduce insulin mediated phosphorylation of AKT. Insulin‐mediated phosphorylation of extracellular regulated kinases (ERK1/2) is not affected. EVs from individuals with obesity decrease insulin stimulated 2‐deoxyglucose uptake in adipocytes (p = 0.0159). Conclusion EVs released by stressed adipocytes impair insulin action in neighboring adipocytes

Extracellular vesicles from hypoxic adipocytes and obese subjects reduce insulin-stimulated glucose uptake

Scope We investigate the effects of extracellular vesicles (EVs) obtained from in vitro adipocyte cell models and from obese subjects on glucose transport and insulin responsiveness. Methods and results EVs are isolated from the culture supernatant of adipocytes cultured under normoxia, hypoxia (1% oxygen), or exposed to macrophage conditioned media (15% v/v). EVs are isolated from the plasma of lean individuals and subjects with obesity. Cultured adipocytes are incubated with EVs and activation of insulin signalling cascades and insulin‐stimulated glucose transport are measured. EVs released from hypoxic adipocytes impair insulin‐stimulated 2‐deoxyglucose uptake and reduce insulin mediated phosphorylation of AKT. Insulin‐mediated phosphorylation of extracellular regulated kinases (ERK1/2) is not affected. EVs from individuals with obesity decrease insulin stimulated 2‐deoxyglucose uptake in adipocytes (p = 0.0159). Conclusion EVs released by stressed adipocytes impair insulin action in neighboring adipocytes

Observational constraints to boxy/peanut bulge formation time

Boxy/peanut bulges are considered to be part of the same stellar structure as bars and both could be linked through the buckling instability. The Milky Way is our closest example. The goal of this letter is determining if the mass assembly of the different components leaves an imprint in their stellar populations allowing to estimate the time of bar formation and its evolution. To this aim we use integral field spectroscopy to derive the stellar age distributions, SADs, along the bar and disc of NGC 6032. The analysis shows clearly different SADs for the different bar areas. There is an underlying old (>=12 Gyr) stellar population for the whole galaxy. The bulge shows star formation happening at all times. The inner bar structure shows stars of ages older than 6 Gyrs with a deficit of younger populations. The outer bar region presents a SAD similar to that of the disc. To interpret our results, we use a generic numerical simulation of a barred galaxy. Thus, we constrain, for the first time, the epoch of bar formation, the buckling instability period and the posterior growth from disc material. We establish that the bar of NGC 6032 is old, formed around 10 Gyr ago while the buckling phase possibly happened around 8 Gyr ago. All these results point towards bars being long-lasting even in the presence of gas.Comment: Accepted for publication in MNRAS Letter

Resolving galaxies in time and space: II: Uncertainties in the spectral synthesis of datacubes

In a companion paper we have presented many products derived from the application of the spectral synthesis code STARLIGHT to datacubes from the CALIFA survey, including 2D maps of stellar population properties and 1D averages in the temporal and spatial dimensions. Here we evaluate the uncertainties in these products. Uncertainties due to noise and spectral shape calibration errors and to the synthesis method are investigated by means of a suite of simulations based on 1638 CALIFA spectra for NGC 2916, with perturbations amplitudes gauged in terms of the expected errors. A separate study was conducted to assess uncertainties related to the choice of evolutionary synthesis models. We compare results obtained with the Bruzual & Charlot models, a preliminary update of them, and a combination of spectra derived from the Granada and MILES models. About 100k CALIFA spectra are used in this comparison. Noise and shape-related errors at the level expected for CALIFA propagate to 0.10-0.15 dex uncertainties in stellar masses, mean ages and metallicities. Uncertainties in A_V increase from 0.06 mag in the case of random noise to 0.16 mag for shape errors. Higher order products such as SFHs are more uncertain, but still relatively stable. Due to the large number statistics of datacubes, spatial averaging reduces uncertainties while preserving information on the history and structure of stellar populations. Radial profiles of global properties, as well as SFHs averaged over different regions are much more stable than for individual spaxels. Uncertainties related to the choice of base models are larger than those associated with data and method. Differences in mean age, mass and metallicity are ~ 0.15 to 0.25 dex, and 0.1 mag in A_V. Spectral residuals are ~ 1% on average, but with systematic features of up to 4%. The origin of these features is discussed. (Abridged)Comment: A&A, accepte

Dissecting galactic bulges in space and time - I. The importance of early formation scenarios versus secular evolution

The details of bulge formation via collapse, mergers, secular processes or their interplay remain unresolved. To start answering this question and quantify the importance of distinct mechanisms, we mapped a sample of three galactic bulges using data from the integral field spectrograph WiFeS on the ANU's 2.3-m telescope in Siding Spring Observatory. Its high-resolution gratings (R ∼ 7000) allow us to present a detailed kinematic and stellar population analysis of their inner structures with classical and novel techniques. The comparison of those techniques calls for the necessity of inversion algorithms in order to understand complex substructures and separate populations. We use line-strength indices to derive single stellar population equivalent ages and metallicities. Additionally, we use full spectral fitting methods, here the code STECKMAP, to extract their star formation histories. The high quality of our data allows us to study the 2D distribution of different stellar populations (i.e. young, intermediate and old). We can identify their dominant populations based on these age-discriminated 2D light and mass contribution. In all galactic bulges studied, at least 50 per cent of the stellar mass already existed 12 Gyr ago, more than currently predicted by simulations. A younger component (age between ∼1 and ∼8 Gyr) is also prominent and its present day distribution seems to be affected much more strongly by morphological structures, especially bars, than the older one. This in-depth analysis of the three bulges supports the notion of increasing complexity in their evolution, likely to be found in numerous bulge structures if studied at this level of detail, which cannot be achieved by mergers alone and require a non-negligible contribution of secular evolution