The chemistry of rainwater has been subject to numerous investigations during the last two decades due to the increase of environmental problems caused by the acid deposition. The present study focuses on one aspect o...The chemistry of rainwater has been subject to numerous investigations during the last two decades due to the increase of environmental problems caused by the acid deposition. The present study focuses on one aspect of air pollution, the chemical composition of wet deposition of an industrial zone. The sampling period was from March to December 2009. The station was located on the roof of the Chemistry School at the University of Nuevo León, an area in the north of Monterrey where the majority of pollution is generated. Twenty-five wet precipitation samples were collected with an automatic sampler and analyzed for pH, ions (, , Cl<sup>-</sup>, Ca<sup>2+</sup>, Mg<sup>2+</sup>, Na<sup>+</sup>, K<sup>+</sup>) and conductivity. The results show that the average pH is higher than 5.6;the characteristics of the rainwater studied are of alkaline nature due to the values of pH found;there is an evident anthropogenic source contributing to the alkaline of rain water. In order to find possible association between ions and consequently the possible sources of pollutants correlation study was applied using the program SPSS v.12. Good correlations were found between ions and along with Ca<sup>2+</sup> and Mg<sup>2+</sup>. The local extraction industry and surrounding aerosols might be causing of alkaline rain which may be due to the neutralization effect of particulate matter. This study represents a continuation of the studies of rainwater chemistry in the Northeast of Mexico.展开更多
The objectives of this paper are to demonstrate the algorithms employed by three statistical software programs (R, Real Statistics using Excel, and SPSS) for calculating the exact two-tailed probability of the Wald-Wo...The objectives of this paper are to demonstrate the algorithms employed by three statistical software programs (R, Real Statistics using Excel, and SPSS) for calculating the exact two-tailed probability of the Wald-Wolfowitz one-sample runs test for randomness, to present a novel approach for computing this probability, and to compare the four procedures by generating samples of 10 and 11 data points, varying the parameters n<sub>0</sub> (number of zeros) and n<sub>1</sub> (number of ones), as well as the number of runs. Fifty-nine samples are created to replicate the behavior of the distribution of the number of runs with 10 and 11 data points. The exact two-tailed probabilities for the four procedures were compared using Friedman’s test. Given the significant difference in central tendency, post-hoc comparisons were conducted using Conover’s test with Benjamini-Yekutielli correction. It is concluded that the procedures of Real Statistics using Excel and R exhibit some inadequacies in the calculation of the exact two-tailed probability, whereas the new proposal and the SPSS procedure are deemed more suitable. The proposed robust algorithm has a more transparent rationale than the SPSS one, albeit being somewhat more conservative. We recommend its implementation for this test and its application to others, such as the binomial and sign test.展开更多
This study aims to establish a rationale for the Rice University rule in determining the number of bins in a histogram. It is grounded in the Scott and Freedman-Diaconis rules. Additionally, the accuracy of the empiri...This study aims to establish a rationale for the Rice University rule in determining the number of bins in a histogram. It is grounded in the Scott and Freedman-Diaconis rules. Additionally, the accuracy of the empirical histogram in reproducing the shape of the distribution is assessed with respect to three factors: the rule for determining the number of bins (square root, Sturges, Doane, Scott, Freedman-Diaconis, and Rice University), sample size, and distribution type. Three measures are utilized: the average distance between empirical and theoretical histograms, the level of recognition by an expert judge, and the accuracy index, which is composed of the two aforementioned measures. Mean comparisons are conducted with aligned rank transformation analysis of variance for three fixed-effects factors: sample size (20, 35, 50, 100, 200, 500, and 1000), distribution type (10 types), and empirical rule to determine the number of bins (6 rules). From the accuracy index, Rice’s rule improves with increasing sample size and is independent of distribution type. It outperforms the Friedman-Diaconis rule but falls short of Scott’s rule, except with the arcsine distribution. Its profile of means resembles the square root rule concerning distributions and Doane’s rule concerning sample sizes. These profiles differ from those of the Scott and Friedman-Diaconis rules, which resemble each other. Among the seven rules, Scott’s rule stands out in terms of accuracy, except for the arcsine distribution, and the square root rule is the least accurate.展开更多
Two motor-cognitive interventions were implemented to evaluate their efficacy in cognitive improvement in Mexican older adults 65 years and more. The intervention group received a dance video games plus a cognitive ta...Two motor-cognitive interventions were implemented to evaluate their efficacy in cognitive improvement in Mexican older adults 65 years and more. The intervention group received a dance video games plus a cognitive task (dual-task);the comparison group received only the dance video game, in sessions of 45 minutes, 3 times a week, for 12 weeks. The Barthel Index and Lawton and Brody Index, the Center for Epidemiologic Studies Depression Scale-Revised were applied the Digit Span Test, the Stroop Test, and Color Trail Making. Gait parameters were assessed by GAITRite? electronic walkway (CIR Systems). The design was quasi-experimental. Sites were randomly assigned to intervention groups. The intervention group started with 32 participants and finished with 15;the comparison group started with 20 participants and finished with 18. Participants in the intervention group had to mimic the dance movement of a video game and, after the second week to name progressively three objects without stopping dancing. A multivariate repeated measures model (MANO-VA) was fit with four variables. A time-by-group interaction was observed in the Stroop test, and Digits Span Backwards was in favor of the dual task group. The Stroop test, Digit Span Backwards, gait speed, and step length showed effect time. Both groups improved in gait speed and step length by the end of the intervention. Results show it is feasible for Mexican older adults with little schooling to perform dual tasks and improve cognitive tasks and gait speed. Limitations were high attrition due to unforeseen situations and small sample size.展开更多
Pachycereus marginatus (DC.) Britton & Rose and Ibervillea sonorae (S. Watson) Greene have been used in the Mexican traditional medicine for the treatment of various diseases, including cancer. The present study a...Pachycereus marginatus (DC.) Britton & Rose and Ibervillea sonorae (S. Watson) Greene have been used in the Mexican traditional medicine for the treatment of various diseases, including cancer. The present study aims to investigate the cytotoxic activity of these plants against a murine lymphoma. Soxhlet extraction of dried and powdered plant material was performed with methanol. Also, a further partitioning of these methanolic extracts with hexane and ethyl acetate was achieved. The in vitro cytotoxic activity against the murine lymphoma L5178Y-R cell line was assessed via the colorimetric MTT assay. The methanol extract from P. marginatus exhibited high cytotoxic activity (up to 94%) at concentrations ranging from 3.9 to 500 μg/mL;however, hexane and ethyl acetate partitions from this methanolic extract showed lower but significant (p < 0.05) concentration-dependent cytotoxicity (hexane partition up to 94% at 500 μg/mL;ethyl acetate partition up to 94% at 65.5 μg/mL). The methanolic extract and partitions derived from I. sonorae also showed significant (p < 0.05) and concentration-dependent cytotoxicity against L5178Y-R cells at concentrations ranging from 7.81 to 500 μg/mL (methanolic extract up to 63% at 500 μg/mL;hexane partition up to 76% at 250 μg/mL;ethyl acetate partition up to 73% at 500 μg/mL). These results demonstrate that the methanol extracts and partitions from P. marginatus and I. sonorae possess significant cytotoxic activity against the murine lymphoma L5178Y-R and validate the ethnobotanical use of these plants for the treatment of diseases consistent with cancer symptomatology. Previous scientific reports describe the isolation of isoquinoline alkaloids of P. marginatus as well as cucurbitacins from I. sonorae, phytochemicals that could be responsible for their observed cytotoxic activity in this research. The direct extraction with methanol of medicinal plants allows extracting of both high and low-polarity compounds, contrary to the simple extraction with water that only allows obtai展开更多
The Cochran-Mantel-Haenszel (CMH) test, developed in the 1950s, is a classic in health research, especially in epidemiology and other fields in which dichotomous and polytomous variables are frequent. This nonparametr...The Cochran-Mantel-Haenszel (CMH) test, developed in the 1950s, is a classic in health research, especially in epidemiology and other fields in which dichotomous and polytomous variables are frequent. This nonparametric test makes it possible to measure and check the effect of an antecedent variable X on a health outcome Y, statistically controlling the effect of a third variable Z that acts as a confounding variable in the relationship between X and Y. Both X and Y are measured on a dichotomous qualitative scale and Z on a polytomous-qualitative or ordinal scale. It is assumed that the effect of X on Y is homogeneous between the k strata of Z, which is usually tested by the Breslow-Day test with the Tarone’s correction or the Woolf’s test. The main statistical programs have the CMH test together with a test to verify the assumption of a homogeneous effect across the strata, so that it is easy to apply. However, its fundamentals and details of calculations are a mystery to most researchers, and even difficult to find or understand. The aim of this article is to present these details in a clear and concise way, including the assumptions and alternatives to non-compliance. This technical knowledge is applied to a simulated realistic example of the area of epidemiology in health and, finally, an interpretive synthesis of the analyses is given. In addition, some suggestions for the test report are made.展开更多
There are several shape measures for quantitative variables, some of which can also be applied to ordinal variables. In quantitative variables, symmetry, peakedness, and kurtosis are essential properties to evaluate t...There are several shape measures for quantitative variables, some of which can also be applied to ordinal variables. In quantitative variables, symmetry, peakedness, and kurtosis are essential properties to evaluate the deviation from assumptions, particularly normality. They aid in selecting the most appropriate method for estimating parameters and testing hypotheses. Initially, these properties serve a descriptive role in qualitative variables. Once defined, they can be considered to check for non-compliance with assumptions and to propose modifications for testing procedures. The objective of this article is to present three measures of the shape of the distribution of a qualitative variable. The concepts of qualitative asymmetry and peakedness are defined. The measurement of the first concept involves calculating the average frequency difference between qualitative categories matched by frequency homogeneity or proximity. For the second concept, the peak-to-shoulder difference and the qualitative percentile kurtosis are taken into consideration. This last measurement is a less effective option than the peak-to-shoulder difference to measure peakedness. A simulated example of the application of these three measures is given and the paper closes with some conclusions and suggestions.展开更多
The aim of this paper is to present a generalization of the Shapiro-Wilk W-test or Shapiro-Francia W'-test for application to two or more variables. It consists of calculating all the unweighted linear combination...The aim of this paper is to present a generalization of the Shapiro-Wilk W-test or Shapiro-Francia W'-test for application to two or more variables. It consists of calculating all the unweighted linear combinations of the variables and their W- or W'-statistics with the Royston’s log-transformation and standardization, z<sub>ln(1-W)</sub> or z<sub>ln(1-W</sub><sub>'</sub><sub>)</sub>. Because the calculation of the probability of z<sub>ln(1-W)</sub> or z<sub>ln(1-W</sub><sub>'</sub><sub>)</sub> is to the right tail, negative values are truncated to 0 before doing their sum of squares. Independence in the sequence of these half-normally distributed values is required for the test statistic to follow a chi-square distribution. This assumption is checked using the robust Ljung-Box test. One degree of freedom is lost for each cancelled value. Defined the new test with its two variants (Q-test or Q'-test), 50 random samples with 4 variables and 20 participants were generated, 20% following a multivariate normal distribution and 80% deviating from this distribution. The new test was compared with Mardia’s, runs, and Royston’s tests. Central tendency differences in type II error and statistical power were tested using the Friedman’s test and pairwise comparisons using the Wilcoxon’s test. Differences in the frequency of successes in statistical decision making were compared using the Cochran’s Q test and pairwise comparisons using the McNemar’s test. Sensitivity, specificity and efficiency proportions were compared using the McNemar’s Z test. The generated 50 samples were classified into five ordered categories of deviation from multivariate normality, the correlation between this variable and p-value of each test was calculated using the Spearman’s coefficient and these correlations were compared. Family-wise error rate corrections were applied. The new test and the Royston’s test were the best choices, with a very slight advantage Q-test over Q'-test. Based on these promising results, further study展开更多
There are several shape measures for quantitative variables, some of which can also be applied to ordinal variables. In quantitative variables, symmetry, peakedness, and kurtosis are essential properties to evaluate t...There are several shape measures for quantitative variables, some of which can also be applied to ordinal variables. In quantitative variables, symmetry, peakedness, and kurtosis are essential properties to evaluate the deviation from assumptions, particularly normality. They aid in selecting the most appropriate method for estimating parameters and testing hypotheses. Initially, these properties serve a descriptive role in qualitative variables. Once defined, they can be considered to check for non-compliance with assumptions and to propose modifications for testing procedures. The objective of this article is to present three measures of the shape of the distribution of a qualitative variable. The concepts of qualitative asymmetry and peakedness are defined. The measurement of the first concept involves calculating the average frequency difference between qualitative categories matched by frequency homogeneity or proximity. For the second concept, the peak-to-shoulder difference and the qualitative percentile kurtosis are taken into consideration. This last measurement is a less effective option than the peak-to-shoulder difference to measure peakedness. A simulated example of the application of these three measures is given and the paper closes with some conclusions and suggestions.展开更多
The objective of this study is to propose the Parametric Seven-Number Summary (PSNS) as a significance test for normality and to verify its accuracy and power in comparison with two well-known tests, such as Royston’...The objective of this study is to propose the Parametric Seven-Number Summary (PSNS) as a significance test for normality and to verify its accuracy and power in comparison with two well-known tests, such as Royston’s W test and D’Agostino-Belanger-D’Agostino K-squared test. An experiment with 384 conditions was simulated. The conditions were generated by crossing 24 sample sizes and 16 types of continuous distributions: one normal and 15 non-normal. The percentage of success in maintaining the null hypothesis of normality against normal samples and in rejecting the null hypothesis against non-normal samples (accuracy) was calculated. In addition, the type II error against normal samples and the statistical power against normal samples were computed. Comparisons of percentage and means were performed using Cochran’s Q-test, Friedman’s test, and repeated measures analysis of variance. With sample sizes of 150 or greater, high accuracy and mean power or type II error (≥0.70 and ≥0.80, respectively) were achieved. All three normality tests were similarly accurate;however, the PSNS-based test showed lower mean power than K-squared and W tests, especially against non-normal samples of symmetrical-platykurtic distributions, such as the uniform, semicircle, and arcsine distributions. It is concluded that the PSNS-based omnibus test is accurate and powerful for testing normality with samples of at least 150 observations.展开更多
Experimental evidence has accumulated to suggest that biologically efficacious informational effects can be derived mimicking active compounds solely through electromagnetic distribution upon aqueous systems affecting...Experimental evidence has accumulated to suggest that biologically efficacious informational effects can be derived mimicking active compounds solely through electromagnetic distribution upon aqueous systems affecting biological systems. Empirically rigorous demonstrations of antimicrobial agent associated electromagnetic informational inhibition of MRSA, Entamoeba histolytica, Trichomonas vaginalis, Candida albicans and a host of other important and various reported effects have been evidenced, such as the electro-informational transfer of retinoic acid influencing human neuroblastoma cells and stem teratocarcinoma cells. Cell proliferation and differentiation effects from informationally affected fields interactive with aqueous systems are measured via microscopy, statistical analysis, reverse transcription polymerase chain reaction and other techniques. Information associated with chemical compounds affects biological aqueous systems, sans direct systemic exposure to the source molecule. This is a quantum effect, based on the interactivity between electromagnetic fields, and aqueous ordered coherence domains. The encoding of aqueous systems and tissue by photonic transfer and instantiation of information rather than via direct exposure to potentially toxic drugs and physical substances holds clear promise of creating inexpensive non-toxic medical treatments.展开更多
BACKGROUND Meckel’s diverticulum （MD） occurs predominantly in chil-dren and adolescents. It is rarely diagnosed in adults. Preoperative diagnosis is diffcult due to low sensitivity of the radiological imaging studi...BACKGROUND Meckel’s diverticulum （MD） occurs predominantly in chil-dren and adolescents. It is rarely diagnosed in adults. Preoperative diagnosis is diffcult due to low sensitivity of the radiological imaging studies. The role of video capsule endoscopy （VCE） in the diagnosis of MD is unknown, and the endoscopic patterns are not defned. We will describe four of our cases of MD evaluated with VCE and make a review of the literature focusing on the endoscopic characteristics.CASE SUMMARYWe present four cases of MD confirmed by surgery. They were all adult males with ages going from 18 to 50 years, referred to our service from 2004 to 2018, due to obscure gastrointestinal bleeding （OGIB）. TheyGarcía-Compeán D et al . Merckel’s diverticulum diagnosis by VCEhad a history of 1 mo to 10 years of overt and occult bleeding episodes. Laboratory blood test showed an iron-deficiency anemia from 4 to 9 g/dL of hemoglo-bin that required multiple hospitalizations and blood transfusions in all cases. Repeated upper digestive endoscopies and colonoscopies were negative. Small bowel was examined with VCE, which revealed double lumen images in all cases, one with polyps and three with circumferential ulcers in the diverticulum. However, based on VCE findings, preoperative diagnosis of MD was suggested only in two patients. Capsule was retain-ed in one patient, which was recovered with surgery. The anatomopathological report revealed ulcerated ectopic gastric mucosa in all cases.CONCLUSIONVCE is useful for the diagnosis of MD. However, endo-scopic characteristics must be recognized in order to establish preoperative diagnosis.展开更多
The normal distribution, which has a symmetric and middle-tailed profile, is one of the most important distributions in probability theory, parametric inference, and description of quantitative variables. However, the...The normal distribution, which has a symmetric and middle-tailed profile, is one of the most important distributions in probability theory, parametric inference, and description of quantitative variables. However, there are many non-normal distributions and knowledge of a non-zero bias allows their identification and decision making regarding the use of techniques and corrections. Pearson’s skewness coefficient defined as the standardized signed distance from the arithmetic mean to the median is very simple to calculate and clear to interpret from the normal distribution model, making it an excellent measure to evaluate this assumption, complemented with the visual inspection by means of a histogram and a box-and-whisker plot. From its variant without tripling the numerator or Yule’s skewness coefficient, the objective of this methodological article is to facilitate the use of this latter measure, presenting how to obtain asymptotic and bootstrap confidence intervals for its interpretation. Not only are the formulas shown, but they are applied with an example using R program. A general rule of interpretation of ∓0.1 has been suggested, but this can only become relevant when contextualized in relation to sample size and a measure of skewness with a population or parametric value of zero. For this purpose, intervals with confidence levels of 90%, 95% and 99% were estimated with 10,000 draws at random with replacement from 57 normally distributed samples-population with different sample sizes. The article closes with suggestions for the use of this measure of skewness.展开更多
Context: Preliminary screening has been undertaken by woody species of Tamaulipan thornscrub for wood density and its utilization northeastern Mexico for different purposes and to find possible relationship of density...Context: Preliminary screening has been undertaken by woody species of Tamaulipan thornscrub for wood density and its utilization northeastern Mexico for different purposes and to find possible relationship of density with wood fibre characteristics. This technique can be used in the selection of species with high wood density for possible utility. Aims: It is to determine the variability in wood density and in fiber cell morphology and its length and among wood species of the Tamaulipan thornscrub, northeastern Mexico. Methods: Wood density and wood fibres are characterized in these woody species following standard methodology. Results: The results reveal large variability in wood density and in fibre cell morphology h. The species have been classified on the basis of wood density and its fibber cell morphology and has been recommended for their possible utilization for different purposes. Conclusions: Species desirable for strong furniture making, paper pulp, soft furniture, fence etc. can be selected on the basis of fibre length to breadth ratios as strong fibres for furniture and fibre cells with broad lumen and thin cell wall use for fabrication of paper pulp and other utilities.展开更多
The objective of this article is to demonstrate with examples that the two-sided tie correction does not work well. This correction was developed by Cureton so that Kendall’s tau-type and Spearman’s rho-type formula...The objective of this article is to demonstrate with examples that the two-sided tie correction does not work well. This correction was developed by Cureton so that Kendall’s tau-type and Spearman’s rho-type formulas for rank-biserial correlation yield the same result when ties are present. However, a correction based on the bracket ties achieves the desired goal, which is demonstrated algebraically and checked with three examples. On the one hand, the 10-element random sample given by Cureton, in which the two-sided tie correction performs well, is taken up. On the other hand, two other examples are given, one with a 7-element random sample and the other with a clinical random sample of 31 participants, in which the two-sided tie correction does not work, but the new correction does. It is concluded that the new corrected formulas coincide with Goodman-Kruskal’s gamma as compared to Glass’ formula that matches Somers’ d<sub>Y</sub><sub>|X</sub> or asymmetric measure of association of Y ranking with respect to X dichotomy. The use of this underreported coefficient is suggested, which is very easy to calculate from its equivalence with Kruskal-Wallis’ gamma and Somers’ d<sub>Y</sub><sub>|X</sub>.展开更多
The present study was undertaken in Forest Science Faculty, Universidad de Nuevo Leon, Mexico on variability of Wood density and its possible relation to few wood chemical composition and wood fiber cell structure ana...The present study was undertaken in Forest Science Faculty, Universidad de Nuevo Leon, Mexico on variability of Wood density and its possible relation to few wood chemical composition and wood fiber cell structure anatomy. The results reveal that among 10 specie studied, there exist a large variation in wood density (0.51 to 1.09), and few wood chemical composition such % carbón (37.14 to 44.07), nitrogen (9.18 to 19.22), sulphur (31.45 to 33/82), lignin (15/28 to 24.35), hemicellulose (19.94 to 27.36%), and % cellulose (33.69 to 45.92). In general, though there was no clear relationship between wood density and other chemical composition of wood. It was observed that the species having moderate to high wood density contained >40% carbón, >30% sulphur and >40% cellulose and more or less 20% lignin. It seems that carbón, sulphur, cellulose and lignin content contribute to greater density. The wood fiber cell with wall lignification seems to be related to higher wood density.展开更多
Reproductive biotechnologies offer us greater possibilities to improve animal genetics. However, the success of these depends on different factors such as the proper selection of the donor female. For this reason, end...Reproductive biotechnologies offer us greater possibilities to improve animal genetics. However, the success of these depends on different factors such as the proper selection of the donor female. For this reason, endocrine markers have been used to evaluate the ovarian reserve, which allow a successful selection of donors. Recent research has shown, among other things, that concentrations greater than 0.130 ng/mL of anti-Mullerian hormone (also known as Muller-inhibiting substance, which is a member of the transforming growth factor beta superfamily of growth and differentiation factors) are related to donors of more than fifteen transferable embryos. Therefore, this review describes studies showing that the measurement of anti-Müllerian hormone concentrations, before superovulation programs, reduces the costs per embryo produced.展开更多
<strong>Introduction:</strong> The World Health Organization establishes that 80% of the world’s population uses traditional medicine for their primary care, because they contain compounds responsible for...<strong>Introduction:</strong> The World Health Organization establishes that 80% of the world’s population uses traditional medicine for their primary care, because they contain compounds responsible for their properties. <strong>Objective:</strong> To evaluate the antifungal effect of the essential oil of <i>Citrus paradisi<span style="white-space:nowrap;"></span></i> against <i>C. albicans<span style="white-space:nowrap;"></span></i> and the cytotoxic effect in three cell lines <em>in vitro</em>. <strong>Methods:</strong> The phytochemical characterization of the oil was carried out by chemical methods and Gas chromatography (GC-MS) and the antifungal effect against <i>C. albicans<span style="white-space:nowrap;"></span></i> (ATCC 90029) was evaluated by the Kirby-Bauer method, which evaluated concentrations of 0.75 - 20 μg/mL and compared with nystatin 100,000 Ul/mL as a positive control. The percentage of the relative inhibitory effect was calculated. The minimum inhibitory concentration (MIC) was determined at 24 hours. Moreover, the cytotoxic effect on <em>C. albicans</em> and cell lines was determined by the colorimetric MTT tetrazolium assay. Finally, the antifungal effect against <em>Candida</em> strains isolated from clinical samples was evaluated at a concentration of 20 μg/mL. <strong>Results:</strong> The essential oil showed an antifungal effect with a percentage of inhibition of 123%. The MIC was 2.5 μg/mL, and the cytotoxicity index was 5.44 μg/mL for <em>C. albicans</em>. The IC50 values were 21.060, 9.482 and 4.176 μg/mL for Vero E6, J774A.1 and MDBK cells respectively. <strong>Conclusion:</strong> These results show the use of <em>C. paradisi</em> essential oil as an alternative treatment in oral antifungal therapy, it is beneficial due to its antifungal effect and its low toxicity on cell cultures.展开更多
文摘The chemistry of rainwater has been subject to numerous investigations during the last two decades due to the increase of environmental problems caused by the acid deposition. The present study focuses on one aspect of air pollution, the chemical composition of wet deposition of an industrial zone. The sampling period was from March to December 2009. The station was located on the roof of the Chemistry School at the University of Nuevo León, an area in the north of Monterrey where the majority of pollution is generated. Twenty-five wet precipitation samples were collected with an automatic sampler and analyzed for pH, ions (, , Cl<sup>-</sup>, Ca<sup>2+</sup>, Mg<sup>2+</sup>, Na<sup>+</sup>, K<sup>+</sup>) and conductivity. The results show that the average pH is higher than 5.6;the characteristics of the rainwater studied are of alkaline nature due to the values of pH found;there is an evident anthropogenic source contributing to the alkaline of rain water. In order to find possible association between ions and consequently the possible sources of pollutants correlation study was applied using the program SPSS v.12. Good correlations were found between ions and along with Ca<sup>2+</sup> and Mg<sup>2+</sup>. The local extraction industry and surrounding aerosols might be causing of alkaline rain which may be due to the neutralization effect of particulate matter. This study represents a continuation of the studies of rainwater chemistry in the Northeast of Mexico.
文摘The objectives of this paper are to demonstrate the algorithms employed by three statistical software programs (R, Real Statistics using Excel, and SPSS) for calculating the exact two-tailed probability of the Wald-Wolfowitz one-sample runs test for randomness, to present a novel approach for computing this probability, and to compare the four procedures by generating samples of 10 and 11 data points, varying the parameters n<sub>0</sub> (number of zeros) and n<sub>1</sub> (number of ones), as well as the number of runs. Fifty-nine samples are created to replicate the behavior of the distribution of the number of runs with 10 and 11 data points. The exact two-tailed probabilities for the four procedures were compared using Friedman’s test. Given the significant difference in central tendency, post-hoc comparisons were conducted using Conover’s test with Benjamini-Yekutielli correction. It is concluded that the procedures of Real Statistics using Excel and R exhibit some inadequacies in the calculation of the exact two-tailed probability, whereas the new proposal and the SPSS procedure are deemed more suitable. The proposed robust algorithm has a more transparent rationale than the SPSS one, albeit being somewhat more conservative. We recommend its implementation for this test and its application to others, such as the binomial and sign test.
文摘This study aims to establish a rationale for the Rice University rule in determining the number of bins in a histogram. It is grounded in the Scott and Freedman-Diaconis rules. Additionally, the accuracy of the empirical histogram in reproducing the shape of the distribution is assessed with respect to three factors: the rule for determining the number of bins (square root, Sturges, Doane, Scott, Freedman-Diaconis, and Rice University), sample size, and distribution type. Three measures are utilized: the average distance between empirical and theoretical histograms, the level of recognition by an expert judge, and the accuracy index, which is composed of the two aforementioned measures. Mean comparisons are conducted with aligned rank transformation analysis of variance for three fixed-effects factors: sample size (20, 35, 50, 100, 200, 500, and 1000), distribution type (10 types), and empirical rule to determine the number of bins (6 rules). From the accuracy index, Rice’s rule improves with increasing sample size and is independent of distribution type. It outperforms the Friedman-Diaconis rule but falls short of Scott’s rule, except with the arcsine distribution. Its profile of means resembles the square root rule concerning distributions and Doane’s rule concerning sample sizes. These profiles differ from those of the Scott and Friedman-Diaconis rules, which resemble each other. Among the seven rules, Scott’s rule stands out in terms of accuracy, except for the arcsine distribution, and the square root rule is the least accurate.
文摘Two motor-cognitive interventions were implemented to evaluate their efficacy in cognitive improvement in Mexican older adults 65 years and more. The intervention group received a dance video games plus a cognitive task (dual-task);the comparison group received only the dance video game, in sessions of 45 minutes, 3 times a week, for 12 weeks. The Barthel Index and Lawton and Brody Index, the Center for Epidemiologic Studies Depression Scale-Revised were applied the Digit Span Test, the Stroop Test, and Color Trail Making. Gait parameters were assessed by GAITRite? electronic walkway (CIR Systems). The design was quasi-experimental. Sites were randomly assigned to intervention groups. The intervention group started with 32 participants and finished with 15;the comparison group started with 20 participants and finished with 18. Participants in the intervention group had to mimic the dance movement of a video game and, after the second week to name progressively three objects without stopping dancing. A multivariate repeated measures model (MANO-VA) was fit with four variables. A time-by-group interaction was observed in the Stroop test, and Digits Span Backwards was in favor of the dual task group. The Stroop test, Digit Span Backwards, gait speed, and step length showed effect time. Both groups improved in gait speed and step length by the end of the intervention. Results show it is feasible for Mexican older adults with little schooling to perform dual tasks and improve cognitive tasks and gait speed. Limitations were high attrition due to unforeseen situations and small sample size.
文摘Pachycereus marginatus (DC.) Britton & Rose and Ibervillea sonorae (S. Watson) Greene have been used in the Mexican traditional medicine for the treatment of various diseases, including cancer. The present study aims to investigate the cytotoxic activity of these plants against a murine lymphoma. Soxhlet extraction of dried and powdered plant material was performed with methanol. Also, a further partitioning of these methanolic extracts with hexane and ethyl acetate was achieved. The in vitro cytotoxic activity against the murine lymphoma L5178Y-R cell line was assessed via the colorimetric MTT assay. The methanol extract from P. marginatus exhibited high cytotoxic activity (up to 94%) at concentrations ranging from 3.9 to 500 μg/mL;however, hexane and ethyl acetate partitions from this methanolic extract showed lower but significant (p < 0.05) concentration-dependent cytotoxicity (hexane partition up to 94% at 500 μg/mL;ethyl acetate partition up to 94% at 65.5 μg/mL). The methanolic extract and partitions derived from I. sonorae also showed significant (p < 0.05) and concentration-dependent cytotoxicity against L5178Y-R cells at concentrations ranging from 7.81 to 500 μg/mL (methanolic extract up to 63% at 500 μg/mL;hexane partition up to 76% at 250 μg/mL;ethyl acetate partition up to 73% at 500 μg/mL). These results demonstrate that the methanol extracts and partitions from P. marginatus and I. sonorae possess significant cytotoxic activity against the murine lymphoma L5178Y-R and validate the ethnobotanical use of these plants for the treatment of diseases consistent with cancer symptomatology. Previous scientific reports describe the isolation of isoquinoline alkaloids of P. marginatus as well as cucurbitacins from I. sonorae, phytochemicals that could be responsible for their observed cytotoxic activity in this research. The direct extraction with methanol of medicinal plants allows extracting of both high and low-polarity compounds, contrary to the simple extraction with water that only allows obtai
文摘The Cochran-Mantel-Haenszel (CMH) test, developed in the 1950s, is a classic in health research, especially in epidemiology and other fields in which dichotomous and polytomous variables are frequent. This nonparametric test makes it possible to measure and check the effect of an antecedent variable X on a health outcome Y, statistically controlling the effect of a third variable Z that acts as a confounding variable in the relationship between X and Y. Both X and Y are measured on a dichotomous qualitative scale and Z on a polytomous-qualitative or ordinal scale. It is assumed that the effect of X on Y is homogeneous between the k strata of Z, which is usually tested by the Breslow-Day test with the Tarone’s correction or the Woolf’s test. The main statistical programs have the CMH test together with a test to verify the assumption of a homogeneous effect across the strata, so that it is easy to apply. However, its fundamentals and details of calculations are a mystery to most researchers, and even difficult to find or understand. The aim of this article is to present these details in a clear and concise way, including the assumptions and alternatives to non-compliance. This technical knowledge is applied to a simulated realistic example of the area of epidemiology in health and, finally, an interpretive synthesis of the analyses is given. In addition, some suggestions for the test report are made.
文摘There are several shape measures for quantitative variables, some of which can also be applied to ordinal variables. In quantitative variables, symmetry, peakedness, and kurtosis are essential properties to evaluate the deviation from assumptions, particularly normality. They aid in selecting the most appropriate method for estimating parameters and testing hypotheses. Initially, these properties serve a descriptive role in qualitative variables. Once defined, they can be considered to check for non-compliance with assumptions and to propose modifications for testing procedures. The objective of this article is to present three measures of the shape of the distribution of a qualitative variable. The concepts of qualitative asymmetry and peakedness are defined. The measurement of the first concept involves calculating the average frequency difference between qualitative categories matched by frequency homogeneity or proximity. For the second concept, the peak-to-shoulder difference and the qualitative percentile kurtosis are taken into consideration. This last measurement is a less effective option than the peak-to-shoulder difference to measure peakedness. A simulated example of the application of these three measures is given and the paper closes with some conclusions and suggestions.
文摘The aim of this paper is to present a generalization of the Shapiro-Wilk W-test or Shapiro-Francia W'-test for application to two or more variables. It consists of calculating all the unweighted linear combinations of the variables and their W- or W'-statistics with the Royston’s log-transformation and standardization, z<sub>ln(1-W)</sub> or z<sub>ln(1-W</sub><sub>'</sub><sub>)</sub>. Because the calculation of the probability of z<sub>ln(1-W)</sub> or z<sub>ln(1-W</sub><sub>'</sub><sub>)</sub> is to the right tail, negative values are truncated to 0 before doing their sum of squares. Independence in the sequence of these half-normally distributed values is required for the test statistic to follow a chi-square distribution. This assumption is checked using the robust Ljung-Box test. One degree of freedom is lost for each cancelled value. Defined the new test with its two variants (Q-test or Q'-test), 50 random samples with 4 variables and 20 participants were generated, 20% following a multivariate normal distribution and 80% deviating from this distribution. The new test was compared with Mardia’s, runs, and Royston’s tests. Central tendency differences in type II error and statistical power were tested using the Friedman’s test and pairwise comparisons using the Wilcoxon’s test. Differences in the frequency of successes in statistical decision making were compared using the Cochran’s Q test and pairwise comparisons using the McNemar’s test. Sensitivity, specificity and efficiency proportions were compared using the McNemar’s Z test. The generated 50 samples were classified into five ordered categories of deviation from multivariate normality, the correlation between this variable and p-value of each test was calculated using the Spearman’s coefficient and these correlations were compared. Family-wise error rate corrections were applied. The new test and the Royston’s test were the best choices, with a very slight advantage Q-test over Q'-test. Based on these promising results, further study
文摘There are several shape measures for quantitative variables, some of which can also be applied to ordinal variables. In quantitative variables, symmetry, peakedness, and kurtosis are essential properties to evaluate the deviation from assumptions, particularly normality. They aid in selecting the most appropriate method for estimating parameters and testing hypotheses. Initially, these properties serve a descriptive role in qualitative variables. Once defined, they can be considered to check for non-compliance with assumptions and to propose modifications for testing procedures. The objective of this article is to present three measures of the shape of the distribution of a qualitative variable. The concepts of qualitative asymmetry and peakedness are defined. The measurement of the first concept involves calculating the average frequency difference between qualitative categories matched by frequency homogeneity or proximity. For the second concept, the peak-to-shoulder difference and the qualitative percentile kurtosis are taken into consideration. This last measurement is a less effective option than the peak-to-shoulder difference to measure peakedness. A simulated example of the application of these three measures is given and the paper closes with some conclusions and suggestions.
文摘The objective of this study is to propose the Parametric Seven-Number Summary (PSNS) as a significance test for normality and to verify its accuracy and power in comparison with two well-known tests, such as Royston’s W test and D’Agostino-Belanger-D’Agostino K-squared test. An experiment with 384 conditions was simulated. The conditions were generated by crossing 24 sample sizes and 16 types of continuous distributions: one normal and 15 non-normal. The percentage of success in maintaining the null hypothesis of normality against normal samples and in rejecting the null hypothesis against non-normal samples (accuracy) was calculated. In addition, the type II error against normal samples and the statistical power against normal samples were computed. Comparisons of percentage and means were performed using Cochran’s Q-test, Friedman’s test, and repeated measures analysis of variance. With sample sizes of 150 or greater, high accuracy and mean power or type II error (≥0.70 and ≥0.80, respectively) were achieved. All three normality tests were similarly accurate;however, the PSNS-based test showed lower mean power than K-squared and W tests, especially against non-normal samples of symmetrical-platykurtic distributions, such as the uniform, semicircle, and arcsine distributions. It is concluded that the PSNS-based omnibus test is accurate and powerful for testing normality with samples of at least 150 observations.
文摘Experimental evidence has accumulated to suggest that biologically efficacious informational effects can be derived mimicking active compounds solely through electromagnetic distribution upon aqueous systems affecting biological systems. Empirically rigorous demonstrations of antimicrobial agent associated electromagnetic informational inhibition of MRSA, Entamoeba histolytica, Trichomonas vaginalis, Candida albicans and a host of other important and various reported effects have been evidenced, such as the electro-informational transfer of retinoic acid influencing human neuroblastoma cells and stem teratocarcinoma cells. Cell proliferation and differentiation effects from informationally affected fields interactive with aqueous systems are measured via microscopy, statistical analysis, reverse transcription polymerase chain reaction and other techniques. Information associated with chemical compounds affects biological aqueous systems, sans direct systemic exposure to the source molecule. This is a quantum effect, based on the interactivity between electromagnetic fields, and aqueous ordered coherence domains. The encoding of aqueous systems and tissue by photonic transfer and instantiation of information rather than via direct exposure to potentially toxic drugs and physical substances holds clear promise of creating inexpensive non-toxic medical treatments.
文摘BACKGROUND Meckel’s diverticulum （MD） occurs predominantly in chil-dren and adolescents. It is rarely diagnosed in adults. Preoperative diagnosis is diffcult due to low sensitivity of the radiological imaging studies. The role of video capsule endoscopy （VCE） in the diagnosis of MD is unknown, and the endoscopic patterns are not defned. We will describe four of our cases of MD evaluated with VCE and make a review of the literature focusing on the endoscopic characteristics.CASE SUMMARYWe present four cases of MD confirmed by surgery. They were all adult males with ages going from 18 to 50 years, referred to our service from 2004 to 2018, due to obscure gastrointestinal bleeding （OGIB）. TheyGarcía-Compeán D et al . Merckel’s diverticulum diagnosis by VCEhad a history of 1 mo to 10 years of overt and occult bleeding episodes. Laboratory blood test showed an iron-deficiency anemia from 4 to 9 g/dL of hemoglo-bin that required multiple hospitalizations and blood transfusions in all cases. Repeated upper digestive endoscopies and colonoscopies were negative. Small bowel was examined with VCE, which revealed double lumen images in all cases, one with polyps and three with circumferential ulcers in the diverticulum. However, based on VCE findings, preoperative diagnosis of MD was suggested only in two patients. Capsule was retain-ed in one patient, which was recovered with surgery. The anatomopathological report revealed ulcerated ectopic gastric mucosa in all cases.CONCLUSIONVCE is useful for the diagnosis of MD. However, endo-scopic characteristics must be recognized in order to establish preoperative diagnosis.
文摘The normal distribution, which has a symmetric and middle-tailed profile, is one of the most important distributions in probability theory, parametric inference, and description of quantitative variables. However, there are many non-normal distributions and knowledge of a non-zero bias allows their identification and decision making regarding the use of techniques and corrections. Pearson’s skewness coefficient defined as the standardized signed distance from the arithmetic mean to the median is very simple to calculate and clear to interpret from the normal distribution model, making it an excellent measure to evaluate this assumption, complemented with the visual inspection by means of a histogram and a box-and-whisker plot. From its variant without tripling the numerator or Yule’s skewness coefficient, the objective of this methodological article is to facilitate the use of this latter measure, presenting how to obtain asymptotic and bootstrap confidence intervals for its interpretation. Not only are the formulas shown, but they are applied with an example using R program. A general rule of interpretation of ∓0.1 has been suggested, but this can only become relevant when contextualized in relation to sample size and a measure of skewness with a population or parametric value of zero. For this purpose, intervals with confidence levels of 90%, 95% and 99% were estimated with 10,000 draws at random with replacement from 57 normally distributed samples-population with different sample sizes. The article closes with suggestions for the use of this measure of skewness.
文摘Context: Preliminary screening has been undertaken by woody species of Tamaulipan thornscrub for wood density and its utilization northeastern Mexico for different purposes and to find possible relationship of density with wood fibre characteristics. This technique can be used in the selection of species with high wood density for possible utility. Aims: It is to determine the variability in wood density and in fiber cell morphology and its length and among wood species of the Tamaulipan thornscrub, northeastern Mexico. Methods: Wood density and wood fibres are characterized in these woody species following standard methodology. Results: The results reveal large variability in wood density and in fibre cell morphology h. The species have been classified on the basis of wood density and its fibber cell morphology and has been recommended for their possible utilization for different purposes. Conclusions: Species desirable for strong furniture making, paper pulp, soft furniture, fence etc. can be selected on the basis of fibre length to breadth ratios as strong fibres for furniture and fibre cells with broad lumen and thin cell wall use for fabrication of paper pulp and other utilities.
文摘The objective of this article is to demonstrate with examples that the two-sided tie correction does not work well. This correction was developed by Cureton so that Kendall’s tau-type and Spearman’s rho-type formulas for rank-biserial correlation yield the same result when ties are present. However, a correction based on the bracket ties achieves the desired goal, which is demonstrated algebraically and checked with three examples. On the one hand, the 10-element random sample given by Cureton, in which the two-sided tie correction performs well, is taken up. On the other hand, two other examples are given, one with a 7-element random sample and the other with a clinical random sample of 31 participants, in which the two-sided tie correction does not work, but the new correction does. It is concluded that the new corrected formulas coincide with Goodman-Kruskal’s gamma as compared to Glass’ formula that matches Somers’ d<sub>Y</sub><sub>|X</sub> or asymmetric measure of association of Y ranking with respect to X dichotomy. The use of this underreported coefficient is suggested, which is very easy to calculate from its equivalence with Kruskal-Wallis’ gamma and Somers’ d<sub>Y</sub><sub>|X</sub>.
文摘The present study was undertaken in Forest Science Faculty, Universidad de Nuevo Leon, Mexico on variability of Wood density and its possible relation to few wood chemical composition and wood fiber cell structure anatomy. The results reveal that among 10 specie studied, there exist a large variation in wood density (0.51 to 1.09), and few wood chemical composition such % carbón (37.14 to 44.07), nitrogen (9.18 to 19.22), sulphur (31.45 to 33/82), lignin (15/28 to 24.35), hemicellulose (19.94 to 27.36%), and % cellulose (33.69 to 45.92). In general, though there was no clear relationship between wood density and other chemical composition of wood. It was observed that the species having moderate to high wood density contained >40% carbón, >30% sulphur and >40% cellulose and more or less 20% lignin. It seems that carbón, sulphur, cellulose and lignin content contribute to greater density. The wood fiber cell with wall lignification seems to be related to higher wood density.
文摘Reproductive biotechnologies offer us greater possibilities to improve animal genetics. However, the success of these depends on different factors such as the proper selection of the donor female. For this reason, endocrine markers have been used to evaluate the ovarian reserve, which allow a successful selection of donors. Recent research has shown, among other things, that concentrations greater than 0.130 ng/mL of anti-Mullerian hormone (also known as Muller-inhibiting substance, which is a member of the transforming growth factor beta superfamily of growth and differentiation factors) are related to donors of more than fifteen transferable embryos. Therefore, this review describes studies showing that the measurement of anti-Müllerian hormone concentrations, before superovulation programs, reduces the costs per embryo produced.
文摘<strong>Introduction:</strong> The World Health Organization establishes that 80% of the world’s population uses traditional medicine for their primary care, because they contain compounds responsible for their properties. <strong>Objective:</strong> To evaluate the antifungal effect of the essential oil of <i>Citrus paradisi<span style="white-space:nowrap;"></span></i> against <i>C. albicans<span style="white-space:nowrap;"></span></i> and the cytotoxic effect in three cell lines <em>in vitro</em>. <strong>Methods:</strong> The phytochemical characterization of the oil was carried out by chemical methods and Gas chromatography (GC-MS) and the antifungal effect against <i>C. albicans<span style="white-space:nowrap;"></span></i> (ATCC 90029) was evaluated by the Kirby-Bauer method, which evaluated concentrations of 0.75 - 20 μg/mL and compared with nystatin 100,000 Ul/mL as a positive control. The percentage of the relative inhibitory effect was calculated. The minimum inhibitory concentration (MIC) was determined at 24 hours. Moreover, the cytotoxic effect on <em>C. albicans</em> and cell lines was determined by the colorimetric MTT tetrazolium assay. Finally, the antifungal effect against <em>Candida</em> strains isolated from clinical samples was evaluated at a concentration of 20 μg/mL. <strong>Results:</strong> The essential oil showed an antifungal effect with a percentage of inhibition of 123%. The MIC was 2.5 μg/mL, and the cytotoxicity index was 5.44 μg/mL for <em>C. albicans</em>. The IC50 values were 21.060, 9.482 and 4.176 μg/mL for Vero E6, J774A.1 and MDBK cells respectively. <strong>Conclusion:</strong> These results show the use of <em>C. paradisi</em> essential oil as an alternative treatment in oral antifungal therapy, it is beneficial due to its antifungal effect and its low toxicity on cell cultures.
