Seasonal time-series imputation of gap missing algorithm (STIGMA)

summary:This work presents a new approach for the imputation of missing data in weather time-series from a seasonal pattern; the seasonal time-series imputation of gap missing algorithm (STIGMA). The algorithm takes advantage from a seasonal pattern for the imputation of unknown data by averaging available data. We test the algorithm using data measured every $10$ minutes over a period of $365$ days during the year 2010; the variables include global irradiance, diffuse irradiance, ultraviolet irradiance, and temperature, arranged in a matrix of dimensions $52,560$ rows for data points over time and $4$ columns for weather variables. The particularity of this work is that the algorithm is well-suited for the imputation of values when the missing data are presented continuously and in seasonal patterns. The algorithm employs a date-time index to collect available data for the imputation of missing data, repeating the process until all missing values are calculated. The tests are performed by removing $5\%$, $10\%$, $15\%$, $20\%$, $25\%$, and $30\%$ of the available data, and the results are compared to autoregressive models. The proposed algorithm has been successfully tested with a maximum of $2,736$ contiguous missing values that account for $19$ consecutive days of a single month; this dataset is a portion of all the missing values when the time-series lacks $30\%$ of all data. The metrics to measure the performance of the algorithms are root-mean-square error (RMSE) and the coefficient of determination ($R^{2}$). The results indicate that the proposed algorithm outperforms autoregressive models while preserving the seasonal behavior of the time-series. The STIGMA is also tested with non-weather time-series of beer sales and number of air passengers per month, which also have a cyclical pattern, and the results show the precise imputation of data

Selective binocular vision loss in two subterranean caviomorph rodents: Spalacopus cyanus and Ctenomys talarum

To what extent can the mammalian visual system be shaped by visual behavior? Here we analyze the shape of the visual fields, the densities and distribution of cells in the retinal ganglion-cell layer and the organization of the visual projections in two species of facultative non-strictly subterranean rodents, Spalacopus cyanus and Ctenomys talarum, aiming to compare these traits with those of phylogenetically closely related species possessing contrasting diurnal/nocturnal visual habits. S. cyanus shows a definite zone of frontal binocular overlap and a corresponding area centralis, but a highly reduced amount of ipsilateral retinal projections. The situation in C. talarum is more extreme as it lacks of a fronto-ventral area of binocular superposition, has no recognizable area centralis and shows no ipsilateral retinal projections except to the suprachiasmatic nucleus. In both species, the extension of the monocular visual field and of the dorsal region of binocular overlap as well as the whole set of contralateral visual projections, appear well-developed. We conclude that these subterranean rodents exhibit, paradoxically, diurnal instead of nocturnal visual specializations, but at the same time suffer a specific regression of the anatomical substrate for stereopsis. We discuss these findings in light of the visual ecology of subterranean lifestylesFil: Vega Zuniga, Tomas. Universidad de Chile; ChileFil: Medina, Felipe. Universidad de Chile; ChileFil: Marin, Gonzalo. Universidad de Chile; ChileFil: Letelier, Juán Carlos. Universidad de Chile; ChileFil: Palacios, Adrián G.. Universidad de Valparaíso; ChileFil: Němec, Pavel. Charles University in Prague; República ChecaFil: Schleich, Cristian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Mpodozis, Jorge. Universidad de Chile; Chil

Star-shaped poly(?-caprolactone)-co-poly(ethylene glycol) synthesized with oxalyl chloride as linker molecule

This paper presents the Static Synchronous Compensator's (StatCom) voltage regulation by a B-spline neural network. The fact that the electric grid is a non-stationary system, with varying parameters and configurations, adaptive control schemes may be advisable. Thereby the control technique must guarantee its performance on an actual operating environment where the StatCom is embedded. The B-spline neural net (B-SNN) is a convenient tool to execute the power system voltage adaptive control, with the possibility of carrying out such tasks on-line and taking into account non-linearities. The proposed controller presents a simple structure, adaptability, fast response, and robustness. The simplicity and performance of such control are exhibited. The applicability of the proposition is tested on a lab prototype. " 2009 IEEE.",,,,,,"10.1109/PTC.2009.5282123",,,"http://hdl.handle.net/20.500.12104/44719","http://www.scopus.com/inward/record.url?eid=2-s2.0-74949138587&partnerID=40&md5=7d4ceb80519e72d80227009c5ee2bcfc",,,,,,,,"2009 IEEE Bucharest PowerTech: Innovative Ideas Toward the Electrical Grid of the Future",,,,,,"Scopus",,,,,,"FACTS; Neural networks; StatCom",,,,,,"StatCom's control by neural networks: Results on a lab prototype",,"Conference Paper" "46503","123456789/35008",,"Alcazar-Gonzalez, V., Univ de Guadalajara, Guadalajara, Mexico; Zuniga-Partiga, V., Univ de Guadalajara, Guadalajara, Mexico; Gonzalez-Alvarez, V., Univ de Guadalajara, Guadalajara, Mexico",,"Alcazar-Gonzalez, V

StatCom's control by neural networks: Results on a lab prototype

This paper presents the Static Synchronous Compensator's (StatCom) voltage regulation by a B-spline neural network. The fact that the electric grid is a non-stationary system, with varying parameters and configurations, adaptive control schemes may be advisable. Thereby the control technique must guarantee its performance on an actual operating environment where the StatCom is embedded. The B-spline neural net (B-SNN) is a convenient tool to execute the power system voltage adaptive control, with the possibility of carrying out such tasks on-line and taking into account non-linearities. The proposed controller presents a simple structure, adaptability, fast response, and robustness. The simplicity and performance of such control are exhibited. The applicability of the proposition is tested on a lab prototype. © 2009 IEEE

A single amino acid residue can determine the sensitivity of SERCAs to artemisinins

Artemisinins are the most important class of antimalarial drugs. They specifically inhibit PfATP6, a SERCA-type ATPase of Plasmodium falciparum. Here we show that a single amino acid in transmembrane segment 3 of SERCAs can determine susceptibility to artemisinin. An L263E replacement of a malarial by a mammalian residue abolishes inhibition by artemisinins. Introducing residues found in other Plasmodium spp. also modulates artemisinin sensitivity, suggesting that artemisinins interact with the thapsigargin-binding cleft of susceptible SERCAs

Formin1 disruption confers oligodactylism and alters Bmp signaling

Proper limb development requires concerted communication between cells within the developing limb bud. Several molecules have been identified which contribute to the formation of a circuitry loop consisting in large part of secreted proteins. The intracellular actin nucleator, Formin 1 (Fmn1), has previously been implicated in limb development, but questions remain after the identification of a Gremlin transcriptional enhancer within the 3′ end of the Fmn 1 locus. To resolve this issue, a knockout mouse devoid of Fmn1 protein was created and characterized. The mice exhibit a reduction of digit number to four, a deformed posterior metatarsal, phalangeal soft tissue fusion as well as the absence of a fibula to 100% penetrance in the FVB genetic background. Importantly, this mutant allele does not genetically disrupt the characterized Gremlin enhancer, and indeed Gremlin RNA expression is upregulated at the 35 somite stage of development. Our data reveal increased Bone Morphogenetic Protein (Bmp) activity in mice which carry a disruption in Fmn1, as evidenced by upregulation of Msx1 and a decrease in Fgf4 within the apical ectodermal ridge. Additionally, these studies show enhanced activity downstream of the Bmp receptor in cells where Fmn1 is perturbed, suggesting a role for Fmn1 in repression of Bmp signaling