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Search Results: 1 - 10 of 6989 matches for " Diego; "
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Estimating the Variance of the Proportion of Contaminated Soil by Petroleum Spills Using Two-Dimensional Systematic Sampling under Different Approaches  [PDF]
Diego Jarquin
Open Journal of Statistics (OJS) , 2018, DOI: 10.4236/ojs.2018.84046
Abstract: In leading petroleum-producing countries like Kuwait, Brazil, Iran, Iraq and Mexico oil spills frequently occur on land, causing serious damage to crop fields. Soil remediation requires constant monitoring of the polluted area. One common monitoring method involves two-dimensional systematic sampling, which can be used to estimate the proportion of the contaminated soil and study the oil spills’ geographic distribution. A well-known issue using this sampling design involves the analytical derivation of variance of the sample mean (proportion), which requires at least two independent samples. To address the problem, this research proposed a variance estimator based on regression and a corrected estimator using the autocorrelation Geary Index under the model-assisted approach. The construction of the estimators was assisted by geo-statistical models by simulating an auxiliary variable. Similar populations to those in real oil spills were recreated, and the accuracy of proposed estimators was evaluated by comparing their performance with other well-known estimators. The factors considered in this simulation study were: a) the model for simulating the populations (exponential and wave), b) the mean and the variance of the process, c) the level of autocorrelation among units. Given the statistical and computing burdens (bias, ratio between estimated and real variance, convergence and computer time), under the exponential model, the regression estimator showed the best performance; and for the wave model, the corrected version performed even better.
Modeling Spatial Data Pooled over Time: Schematic Representation and Monte Carlo Evidences  [PDF]
Jean Dubé, Diego Legros
Theoretical Economics Letters (TEL) , 2015, DOI: 10.4236/tel.2015.51018
Abstract: The spatial autocorrelation issue is now well established, and it is almost impossible to deal with spatial data without considering this reality. In addition, recent developments have been devoted to developing methods that deal with spatial autocorrelation in panel data. However, little effort has been devoted to dealing with spatial data (cross-section) pooled over time. This paper endeavours to bridge the gap between the theoretical modeling development and the application based on spatial data pooled over time. The paper presents a schematic representation of how spatial links can be expressed, depending on the nature of the variable, when combining the spatial multidirectional relations and temporal unidirectional relations. After that, a Monte Carlo experiment is conducted to establish the impact of applying a usual spatial econometric model to spatial data pooled over time. The results suggest that neglecting the temporal dimension of the data generating process can introduce important biases on autoregressive parameters and thus result in the inaccurate measurement of the indirect and total spatial effect related to the spatial spillover effect.
Land Productivity Changes in a Trade Liberalization Environment: Mexico under NAFTA  [PDF]
Diego de la Fuente Stevens
Theoretical Economics Letters (TEL) , 2014, DOI: 10.4236/tel.2014.43030

The focus of this research is the understanding of a fundamental aspect of the Mexican agricultural sector: the evolution of land productivity and the sources behind its changes. The study takes place in a period that runs from 1990 to 2011, a period of large structural transformations in the Mexican economy. The research offers answers regarding how the sector has adapted in terms of crop selection. Results show that a large share of total agricultural land productivity changes happened due to intrinsic changes in crop productivity; while these changes have different sources, most of them were the result of changes in production patters across states. Furthermore, around one quarter of total productivity, changes resulted from a better selection of crops in terms of productivity levels.

Modified Newtonian Dynamics as an Entropic Force  [PDF]
Diego A. Carranza, Sergio Mendoza
Journal of Modern Physics (JMP) , 2015, DOI: 10.4236/jmp.2015.66084
Abstract: Under natural assumptions on the thermodynamic properties of space and time with the holo-graphic principle, we reproduce a MOND-like behaviour of gravity on particular scales of mass and length, where Newtonian gravity requires a modification or extension if no dark matter component is introduced in the description of gravitational phenomena. The result is directly obtained with the assumption that a fundamental constant of nature with dimensions of acceleration needs to be introduced into gravitational interactions. This in turn allows for modifications or extensions of the equipartion law and/or the holographic principle. In other words, MOND-like phenomenology can be reproduced when appropriate generalised concepts at the thermodynamical level of space and/or at the holographic principle are introduced. Thermodynamical modifications are reflected in extensions to the equipartition law which occur when the temperature of the system drops below a critical value, equals to Unruh’s temperature evaluated at the acceleration constant scale introduced for the description of the gravitational phenomena. Our calculations extend the ones by [1] in which Newtonian gravity is shown to be an emergent phenomenon, and together with it reinforces the idea that gravity at all scales is emergent.
Nested derivatives: a simple method for computing series expansions of inverse functions
Diego Dominici
International Journal of Mathematics and Mathematical Sciences , 2003, DOI: 10.1155/s0161171203303291
Abstract: We give an algorithm to compute the series expansion for the inverse of a given function. The algorithm is extremely easy to implement and gives the first N terms of the series. We show several examples of its application in calculating the inverses of some special functions.
Asymptotic analysis of powers of matrices
Diego Dominici
International Journal of Mathematics and Mathematical Sciences , 2006, DOI: 10.1155/ijmms/2006/79617
Abstract: We analyze the representation of An as a linear combination of Aj, 0≤j≤k−1, where A is a k×k matrix. We obtain a first-order asymptotic approximation of An as n→∞, without imposing any special conditions on A. We give some examples showing the application of our results.
On Integer Numbers with Locally Smallest Order of Appearance in the Fibonacci Sequence
Diego Marques
International Journal of Mathematics and Mathematical Sciences , 2011, DOI: 10.1155/2011/407643
Abstract: Let be the th Fibonacci number. The order of appearance () of a natural number is defined as the smallest natural number such that divides . For instance, for all =≥5, we have (?1)>()<(
Changes in Peak Flow Value during Immunotherapy Administration
Diego Saporta
Journal of Environmental and Public Health , 2012, DOI: 10.1155/2012/212867
Abstract: Nasal allergies are prevalent affecting a large percentage of the population. Not only the upper respiratory tract but the whole body is involved. Allergies produce morbidity (and even occasional mortality) as they can lead to asthma development, and increased number of accidents. Immunotherapy results can be evaluated by following symptom scores, medication use, and objective measurements. Using a Peak Flow Meter (PFM) to evaluate immunotherapy results, it became evident that patients with and without asthma exhibited an improvement in the Peak Flow (PF) value, suggesting that lower airway involvement in allergic patients could be more prevalent than assumed. A consecutive chart review was performed including patients of any age with nasal allergies (with or without asthma) treated with immunotherapy for at least 6 months that had at least 2 complete evaluations. When immunotherapy was successful, most patients exhibited an increase in the PF value regardless of asthma status. A very significant finding was that most allergy sufferers may have lower airway inflammation. The use of the PF value to assess immunotherapy results and the potential failure to diagnose asthma in allergy sufferers are discussed. A better diagnosis of lower airway inflammation could be substantial in the management of these patients.
Efficacy of Sublingual Immunotherapy versus Subcutaneous Injection Immunotherapy in Allergic Patients
Diego Saporta
Journal of Environmental and Public Health , 2012, DOI: 10.1155/2012/492405
Abstract: While it is generally accepted that Subcutaneous Injection Immunotherapy (SCIT) and Sublingual Immunotherapy (SLIT) are both efficacious, there is not yet a significant amount of information regarding their comparative efficacy. In this paper, we performed a retrospective chart review and compared treatment results in two groups of patients (both with nasal allergies with or without asthma) that were treated either with SCIT or SLIT. Both treatment modalities were found to be of similar efficacy.
Quality Health Care in the European Union Thanks to Competition Law
Diego Fornaciari
International Journal of Environmental Research and Public Health , 2010, DOI: 10.3390/ijerph7010001
Abstract: There are many biases concerning the application of competition law in health care. Quality concerns can however be integrated into competition law analysis. The aim of this paper is to identify the links between the application of competition law in the European Union and the right to quality health care and to point out the problems that arise when integrating quality concerns in competition law analysis. Guidelines must be issued and competition authorities must work together with institutions that have expertise in the field of health care quality measurement in order to integrate these dimensions in competition practice.
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