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Copyright of Revista Enfoques: Ciencia Política y Administración Pública is the property of Universidad Central de Chile and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Economía, Sociedad y Territorio is the property of El Colegio Mexiquense and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Residential mobility is a material and symbolic practice that is part of social production in urban space. Physical and social conditions and the representation of the geographic space in which the current and future residents are located are fundamental factors in the decisions that individuals and families make when changing residence. Each social group, differentiated by their nationality, ethnicity, age, or socioeconomic status, appraises the advantages and disadvantages of each location in a different way, and this generates different spatial patterns of residential mobility. We study at various scales the functional and spatial configurations of the changes of residence of a group of Spaniards and foreigners that occurred in the city of Zaragoza (Spain) between 2003 and 2017. This is understood as a relational network of places connected by origin-destination flows of changes of residence. Individual data aggregated in census sections have been used with a methodology that combines spatial analysis procedures and geosocial networks. Results show that the residential mobility networks of both groups have different functional organisations in different spaces. The effects of residential mobility are manifested by variations in the volume of the population and the sociodemographic composition of each area. Finally, the distribution of the distances involved in changes of residence of Spaniards and foreigners was well adjusted to a lognormal model, which enables accurately predicting the location of a residence. [ABSTRACT FROM AUTHOR]

Copyright of Biomédica: Revista del Instituto Nacional de Salud is the property of Instituto Nacional de Salud of Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Throughout the data of the National Forest and Soil Inventory (INFyS) of Mexico, it is not uncommon to find clusters with less than four subplots (incomplete). The consequences of this condition on the forest parameters estimates are yet to be completely analyzed. The main objective of this work was to compare the behavior of different sampling estimators under such conditions of cluster completeness. Using an artificial population of 9,370,000 trees, created on a 10,000 ha surface, a total of 88 systematic sampling grids using four-plot circular clusters were set. Each grid had 81 clusters, separated by 1 km. On each sampling grid, three different completeness conditions were tested: a) full completeness (all clusters with four subplots) b) 88% completeness and c) 63% completeness. On each condition, timber volume (m³ ha-1) and tree density (tree ha-1) were estimated using the following estimators: 1) Forest Inventory and Analysis (FIA) 2) Van Deusen Estimators 3) Means of ratio and 4) Ratio of means. The estimators were evaluated using relative bias on the mean and the variance. For volume, on each of the three completeness conditions, the mean estimates were similar and unbiased using the proposed four estimators. Nevertheless, the FIA estimator produced biased variance estimates ranging from two to five times larger for 88% and 63% completeness respectively. Similar behavior was observed on tree density. The FIA estimators will produce biased results on the variance estimator when a high percentage of clusters is incomplete. [ABSTRACT FROM AUTHOR]

Copyright of Comunicaciones en Estadística is the property of Universidad Santo Tomas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In practice, complications can arise when constructing optimal designs for non-linear regression models. One of the major problems is when the observations are correlated, since they are taken from the same individual, object or experimental unit. When using the D-optimality criterion, it depends both on the parameter vector of the model and on the correlation structure assumed for the error term. One way to avoid this dependence is through the inclusion of a priori distributions in the D-optimality criterion. In this paper we study the effect of the choice of different a priori distributions, such as the Uniform, Gamma and Lognormal distributions in obtaining the D-optimal designs for a non-linear model, when the errors present different correlation structures. The designs are found by maximizing the approximate D-optimality criterion by the Monte Carlo method. In addition, a general methodology is proposed to find D-optimal designs for any type of non-linear model in the presence of correlated observations. Finally, it is proposed to compare the designs found by calculating the efficiencies taking as a reference design the one obtained with the a priori Uniform distribution. The methodology established in a case study is applied, and it is concluded that the designs obtained depend as much on the correlation structure as on the a priori distribution considered. [ABSTRACT FROM AUTHOR]

Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Resources estimation of the copper grade values (Cu) using geostatistical methods was carried out in the "Hierro Mantua" (Cobre Mantua) mineral deposit, which is located at the north-west of Pinar del Río province, Cuba. The geologic complexities in the region of the deposit indicate the nonexistence of homogeneity in the Cu values. The structural analysis showed a high asymmetric distribution in the variable studied. The non-existence of normality was verified by different mean and median values, a coefficient of variability greater than one, and the moving windows statistics of the mean was different. Under the previous conditions the data were log-transformed to assure the necessary stationarity in them and consequently to achieve an adequate accuracy in the resources estimation, using a rational Selecting Mining Unit (SMU). The log-transformed data revealed a homogeneous behavior in Cu grade values, demonstrated by better results in basic and moving windows statistics. Semivariograms showed defined structures with anisotropy in the 0° and 90° directions (considering 0 to the north). To apply the Lognormal Kriging estimation is the main objective of this work, because of the complexities of the geology in the studied area. [ABSTRACT FROM AUTHOR]

The sea clutter is a random interfering signal that appears in radar readings caused by the reflection experienced by the emission over the sea surface. After a deep review on the related literature, 23 statistical distributions or models were found for representing sea clutter. The authors classified these models into five groups taking into account the frequency of use and the importance of each distribution. The performed review has two main achievements. Firstly, the mathematical expressions for the distributions were gathered and unified, which contributes to the homogenization of the studies. Secondly, a wide set of candidate distributions were offered enabling the execution of new investigations related to the fit of statistical distributions to empirical clutter data. The investigation strongly recommends the use of 15 distributions, while common studies rarely used more than four. [ABSTRACT FROM AUTHOR]

This article presents the results of the comparison done using five methodologies for the fitting of parameters of a shifted lognormal distribution. The methods considered in this research are: the method of moments, the method of local maximum likelihood, a method proposed by Nagatsuka and Balakrishnan, a modification of this latter method, and a new method proposed in this article. The method of local maximum likelihood provided estimators with good properties when the sample size is not too small and the method did not fail. On the other hand, the modified method of Nagatsuka and Balakrishnan exhibited the best performance from the point of view of the mean squared error. The new method proposed in this work exhibited the best performance from the point of view of a measure of goodness of fit. [ABSTRACT FROM AUTHOR]

Copyright of Revista Electrónica Redes de Ingeniería is the property of Universidad Distrital Francisco Jose de Caldas, Facultad de Ingenieria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales is the property of Academia Colombiana de Ciencias Exactas, Fisicas y Naturales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, a study of different expressions is done for the estimation of the average flow velocity in open channels based on classical fluids mechanics for open channel flow, with empirical and theoretical basement, such as the Manning and Keulegan formulae mentioned by Chow, such as the generalization developed by Aldama-Ocón taking into account a logarithmic distribution of velocities. For this approach, the main problem is the correct estimation of parameter, and the results of Talmaza are presented because its better estimation of the fluid resistance. A potential formula for the average flow velocity, that includes the Manning formula is proposed by the authors. Finally, the theoretical interpretation of flow resistance is developed generalizing the one by Chow. [ABSTRACT FROM AUTHOR]