Fisher's Transformation Research Articles

The personal concept of resort rehabilitation in the reflective projection of a security subject

Improvement of public health promotion practice at Russian resorts is constrained by insufficient knowledge and, therefore, a weak consideration of psychological factors for choosing the favorable rest conditions. The role of subject reflection of the safety of resort components remains underestimated. To identify the structural-content and functional features of the personal concept of a resort rehabilitation subject, which is determined by the reflection of security measures at a resort. The sample consisted of 200 rehabilitation subjects in the Russian Caucasian Spas and foreign resorts. There was no medical intervention. The study was conducted in 2017-2018. The methods used were unstructured interviews, questionnaires, and expert evaluation. Fisher's angular transformation, Student's t-test, and methods for cluster and correlation analyses were used for data processing. The structure of the targeting and organizational components of the personal concept of resort rehabilitation subjects was detailed. There were statistically significant differences in the blocks of personal concepts of the subjects differentiated by the place of resort rehabilitation and the type of a resort plan. The personal concept of a resort rehabilitation subject sets motivational selectivity of its choice of resort conditions. The variability of the resort choice is accompanied by differences in the personal concepts of rehabilitation subjects: the foreign resorts are attractive because of their comfortable conditions and high-quality service; the Russian resorts are promising in health resumption; the orientative-searching choice of a resort is characterized by the priority of novelty and high-quality board and lodging; the sustainable choice for a resort is the priority of obtaining the expected results of rehabilitation, as well as the conditions of stay at the resort. The reflection of security determines the content and structural organization of the personal concept of a resort rehabilitation subject. The personal concept of the resort rehabilitation subject is based on the unity of the targeting and organizational components, one of which combines the objectives of recovery, high-quality board and lodging, and new opportunities; the other is the compliance with the basic and contextual conditions of rest. The bilateral relations between the components of the personal concept of the resort health promotion subject determine the selective orientation of the subjects to specific rest conditions, depending on the expected result. The differences in subject priorities of the place of rest and the type of its planning are accompanied by significant variations in the personal concept of a resort rehabilitation subject. The study identified the features of self-consciousness of the subjects as the psychological bases for their choice of rest conditions in the resort areas. The findings determine the direction of administrative, advertising, and marketing promotion of the development of Russian resorts.

Особенности формирования мышления в условиях цифровой среды

The purpose of the research is to identify the features of young men's thinking, whose mental development carried out in conditions of life virtualization (in a network society). Material and methods. The study involved 319 mentally healthy respondents who study in the universities of St. Petersburg at the specialties associated with computer technology. The control group consists of the 45 respondents from 38 to 50 years. The choice of the control group is related to the fact that the thinking of people of this age category was formed in the pre-digital era. The research program includes classical pathopsychological methods "Exclusion of excess" and "Comparison of concepts". Results and conclusion. The modern youth thinking diagnosis revealed the existence of "pseudo-psychopatological" thinking phenomena (РPF). The answers based on latent signs, various variants of distortion of generalization and lack of generalization were assigned to РPF. PPF considered as having cultural and historical genesis. Comparison of the two samples according to the incidence rate of the РТP by Fisher's angular transformation method showed that the differences between the percentages of the prevalence of the test feature between the groups are significant. The research of the modern youth` thinking shows the increasing of the РPF `number specific to the modern mental norm. Generalizations based on latent signs, broad generalizations, as well as a number of parameters characteristic of distortion of thinking, should not be considered as specific indicators of thinking disorders, since they can occur normally. The results should be considered in evaluation of the results of pathopsychological experiments for clarification of norm and pathology of mental activity markers.

Optimizing methods to quantify intramuscular fat in rotator cuff tears with normalization.

To determine which normalization method may best account for confounding individual factors, such as age or BMI, when quantifying fat infiltration on MRI in patients with rotator cuff tears, the effects of normalization using three different muscles (teres major; triceps brachii; teres minor) were compared. Thirty-seven consecutive patients diagnosed with rotator cuff pathology were included. MRI fat-water sequences were used to quantify rotator cuff intramuscular fat (%fat). Three reference muscles (teres major, triceps, teres minor) were used to derive normalized %fat. Relationships between intramuscular %fat and tear size, age, and BMI in each rotator cuff muscle, before and after normalization, were compared with Fisher transformations (α = 0.05). Normalization with teres major ameliorated confounding relationships of age and BMI on rotator cuff %fat. In contrast, normalization with triceps maintained the confounding relationships between %fat and age in supraspinatus (p = 0.03) and infraspinatus/teres minor (p = 0.028). Normalization with teres minor maintained the confounding relationship between %fat and BMI in subscapularis (p = 0.039). Normalization with teres major best-maintained relationships between tear size and infraspinatus/teres minor %fat (p = 0.021). In contrast, normalization with triceps or teres minor eliminated all significant relationships with tear size. Results of this pilot study suggest normalization to teres major using MRI-based %fat quantification methods can effectively control for individual factors, such as BMI or age, and may have utility in evaluating and monitoring rotator cuff fat infiltration attributed specifically to a tendon tear.

Automated tube voltage selection in pediatric non-contrast chest CT.

BackgroundModern CT scanners provide automatic dose adjustment systems, which are promising options for reducing radiation dose in pediatric CT scans. Their impact on patient dose, however, has not been investigated sufficiently thus far.ObjectiveTo evaluate automated tube voltage selection (ATVS) in combination with automated tube current modulation (ATCM) in non-contrast pediatric chest CT, with regard to the diagnostic image quality.Materials and methodsThere were 160 non-contrast pediatric chest CT scans (8.7±5.4 years) analyzed retrospectively without and with ATVS. Correlations of volume CT Dose Index (CTDIvol) and effective diameter, with and without ATVS, were compared using Fisher’s z-transformation. Image quality was assessed by mean signal-difference-to-noise ratios (SDNR) in the aorta and in the left main bronchus using the independent samples t-test. Two pediatric radiologists and a general radiologist rated overall subjective Image quality. Readers’ agreement was assessed using weighted kappa coefficients. A p value <0.05 was considered significant.ResultsCTDIvol correlation with the effective diameter was r = 0.62 without and r = 0.80 with ATVS (CI: -0.04 to -0.60; p = 0.025). Mean SDNR was 10.88 without and 10.03 with ATVS (p = 0.0089). Readers’ agreement improved with ATVS (weighted kappa between pediatric radiologists from 0.1 (0.03–0.16) to 0.27 (0.09–0.45) with ATVS; between general and each pediatric radiologist from 0.1 (0.06–0.14) to 0.12 (0.05–0.20), and from 0.22 (0.11–0.34) to 0.36 (0.24–0.49)).ConclusionATVS, combined with ATCM, results in a radiation dose reduction for pediatric non-contrast chest CT without a loss of diagnostic image quality and prevents errors in manual tube voltage setting, and thus protecting larger children against an unnecessarily high radiation exposure.

DCARS: differential correlation across ranked samples.

Genes act as a system and not in isolation. Thus, it is important to consider coordinated changes of gene expression rather than single genes when investigating biological phenomena such as the aetiology of cancer. We have developed an approach for quantifying how changes in the association between pairs of genes may inform the outcome of interest called Differential Correlation across Ranked Samples (DCARS). Modelling gene correlation across a continuous sample ranking does not require the dichotomisation of samples into two distinct classes and can identify differences in gene correlation across early, mid or late stages of the outcome of interest. When we evaluated DCARS against the typical Fisher Z-transformation test for differential correlation, as well as a typical approach testing for interaction within a linear model, on real TCGA data, DCARS significantly ranked gene pairs containing known cancer genes more highly across several cancers. Similar results are found with our simulation study. DCARS was applied to 13 cancers datasets in TCGA, revealing several distinct relationships for which survival ranking was found to be associated with a change in correlation between genes. Furthermore, we demonstrated that DCARS can be used in conjunction with network analysis techniques to extract biological meaning from multi-layered and complex data. DCARS R package and sample data are available at https://github.com/shazanfar/DCARS. Publicly available data from The Cancer Genome Atlas (TCGA) was used using the TCGABiolinks R package. Supplementary Files and DCARS R package is available at https://github.com/shazanfar/DCARS. Supplementary data are available at Bioinformatics online.

CORRECTION OF HYPODINAMY AS A FACTOR OF THE RISK OF OBESITY DEVELOPMENT IN FIRE-RESCUERS

Aim. To evaluate the effectiveness of the developed special sports complex in the prevention of hypodynamia and obesity among firefighters-rescuers.Materials and methods. A survey of 490 men with no history of chronic infectious and non-infectious diseases aged 20-59 was conducted. 328 people were the main group, 162 people were the control group. The baseline data included anthropometric development indicators, bioimpedance test results, the extraction of biochemical blood test results; the body mass index (BMI) and the ratio of waist and hip circumference were determined. A questionnaire was conducted to identify hypodynamia (according to the IPAQ questionnaire) and the nutrition structure (according to the questionnaire on the food label literacy questionnaire, past). Both questionnaires were adapted to the Russian Federation. Statistica for Windows 8.0 was used for statistical processing. We used a comparison of the means of the Student method. To compare the values expressed in percent, the method of inverse trigonometric Fisher transformations was used.Results. We have developed and proposed for firefighters-rescuers, included in the main group, special sports complexes, which were used for 6 months. These complexes represent additional physical training by the developed method. There are two of them: one with an emphasis on the prevention and rehabilitation of people with osteochondrosis of the lumbar spine, and the other for cervical and thoracic localization, including with a syndrome of shoulder-scapular periarthritis.Classes were held 3 times a week, the duration of 1 session was 45-50 minutes. The choice of the complex was carried out at the request of firefighters-rescuers. The first complex was selected by 52 people. Based on the results of the study, against the background of the use of sports complexes, there was a 2-fold decrease in the incidence of obesity. Such a high efficiency is due to the fact that obesity of the I degree prevailed among the firefighters-rescuers. In addition, the frequency of occurrence of dyslipidemia, hyperglycemia, and hypodynamia decreased.Conclusion. The use of this sports complex can reduce the risk factors for development of disability among rescue firefighters by preventing hypodynamia and reducing the incidence of hyperglycemia and dyslipidemia, as factors in the development of obesity.

Reliable Signals Based on Fisher Transform for Algorithmic Trading

Abstract Trading and investment on financial markets are common activities today. A very high number of investors, companies, public or private funds are buying and selling every day with a single purpose: the profit. The common questions for any market participant are: when to buy, when to sell and when is better to stay away from the market risk. In order to answer all these questions, many trading strategies are used to establish the best moments to entry or to exit the trades. Due to the large price volatility, a significant part of the trades is set up automatically today by computers using algorithmic trading procedures. For this particular field, special aspects must be met in order to automate the trading process. This paper presents one of these mathematical models used in automated trading systems, a method based on the Fisher transform. A general form of this method will be presented, the functional parameters and the way to optimize them in order to reduce the risk. It will be also suggested a method to build reliable trading signals with the Fisher function in order to be automated. Three different trading signal types will be explained together with the significance of the functional parameters in the price field. A code sample will be included in this paper to prove the simplicity of this method. Real results obtained with the Fisher trading signals will be also presented, compared and analyzed in order to show how this method can be implemented in algorithmic trading.

Does the birth weight have any influence on the persistence of bronchial asthma during childhood period of life?

Objective. To study the clinical-anamnestic features of the bronchial asthma course in schoolchildren who were born with low birth weight (LBW). Material and methods. To achieve the goal of the research a cohort of school-age children (61 patients) with persistent bronchial asthma (BA) who were receiving in-patient treatment at the Regional Children's Clinical Hospital in Chernivtsi was formed by a simple random sample. Depending on the patients' birth body weight two groups of clinical observation were formed. The first (I) clinical group included 35 children with low birth weight (≤ 2500 g), and the second (II) control group consisted of 26 patients with birth body weight > 2500 g. The main clinical characteristics (age, gestational age, and residency) of the comparison groups were comparable. These survey results were analyzed by the methods of parametric (Pt, Students’ criteria) and nonparametric (Pφ, Fisher's angular transformation) methods of calculation. The research was conducted in compliance with the rules of ethical principles of carrying out scientific medical research with the participation of a humans, approved by the Helsinki Declaration (1964-2013) and corresponding orders of the Health Ministry of Ukraine. Results. The analysis of the data has showed the prevalence of the females in the group of patients who were born with LBW (60% of patients in the I clinical group of observation and 34.6% of cases in the II group of comparison (P 0,05). In children with low birth weight the debut of BA in the preschool age (3-6 years) occurred much more frequently (37.1% of observations) than in patients of the II group of comparison (3.8% of cases) (Pφ 0.05). An allergic anamnesis burden on maternal pedigree was noted three times more frequently (34.3% of cases) in patients born with LBW comparing to the II clinical group (16% of observations; Рφ 0.05). Conclusions. Thus, bronchial asthma in children born with LBW was characterized by: prevalence of female patients; the onset of the disease in preschool age (at 3-6 years); a deficiency of patients' body mass during an actual examination that was associated with the social status of this cohort of patients (31.6% of children were orphans or half- orphans) and mother's tobacco use; accommodation of patients in zones of high technological pollution of the environment; the burden of an allergic anamnesis according to the maternal pedigree; the predominance of the triggering role of specific provocative factors (inhalation and food allergens, pharmaceutical drugs) in the asthma exacerbation.

Mechanisms of illegal aggressive behavior of women suffering from schizophrenia

Цель. Установление сравнительных клинико-психопатологических и социальных факторов, способствующих реализации внутрисемейных и внесемейных агрессивных действий женщин, страдающих шизофренией, при сопоставлении механизмов совершения противоправных действий.&#x0D; Методы. Представлены данные исследования 91 пациентки с установленным по Международной классификации болезней 10-го пересмотра диагнозом «шизофрения» (F20.0), непрерывного и эпизодического с нарастающим дефектом типом течения, совершивших агрессивные общественно опасные действия, находящихся на принудительном лечении в Казанской психиатрической больнице специализированного типа с интенсивным наблюдением. Были выделены две группы: первая группа - 57 пациенток, совершивших агрессивные криминальные действия внутри семьи, вторая группа - 34 пациентки, совершившие криминальные действия, направленные против личности, вне семьи. Проведено сравнение между двумя основными научными концепциями по изучению причин и условий совершения психически больными противоправных действий. Осуществлено определение статистической значимости различий сравниваемых величин (по критерию углового преобразования Фишера, критерию Манна-Уитни).&#x0D; Результаты. Сравнительное изучение концепций анализа противоправного поведения у женщин, страдающих шизофренией, показало, что при использовании концепции психопатологических механизмов результаты оказались более детализированными. Так, при продуктивно-психотическом механизме императивные галлюцинации и автоматизмы чаще отмечены у женщин первой группы - 59,5% (p1 &lt;0,01), во второй группе - 28%. Продуктивно-психотический механизм с бредом, установленный в 68% случаев во второй группе, значимо преобладал по частоте над первой группой (p1 &lt;0,01), где выявлялся при совершении криминальных действий у 38,1% пациенток. Бредовую месть чаще отмечали у женщин второй группы - 28% (p1 &lt;0,05), чем в первой группе - 7,1%.&#x0D; Вывод. Наличие психического расстройства в форме шизофрении не всегда определяет реализацию агрессивного противоправного поведения строго по психопатологическому механизму; при этом противоправные действия пациенток, совершённые по негативно-личностному механизму, близки к мотиву правонарушения у женщин, признаваемых вменяемыми.

The contribution of gender differences in motor, behavioral and cognitive features to functional capacity, independence and quality of life in patients with Huntington's disease

IntroductionHuntington's disease (HD) is a neurodegenerative autosomal dominant disorder affecting patients' motor, behavioral and cognitive domains leading to total dependency for activities of daily life. This study compares whether gender differences in motor, cognitive and behavioral symptoms affect function and how functional impairment affects quality of life (QoL). MethodsWe recruited 2191 subjects from the REGISTRY data base that provides personal data, HD age of onset, visit date, CAG mutation size, UHDRS and TFC scores from at least one visit. For 1166 participants SF-36 was also available. We calculated Spearman coefficients for correlations between particular symptomatic domains and functional scales, Fisher z-transform was used to test whether differences in correlations between genders were statistically significant. Simultaneous linear regression with least-square fit method was used to determine for how much variability in functional scales the particular symptomatic domains are responsible. ANOVA was used to look for QoL differences between TFC-stage based groups. Baseline statistics showed no significant differences between genders. ResultsMotor, cognitive and behavioral domains contributed significantly to function and independence. The motor domain contributed most followed by the cognitive and to a lesser degree by the behavioral domain. Motor symptoms correlated more with functional ability and influenced function variability more in women than in men. The decline in functional abilities correlated significantly with QoL decline. ConclusionMotor symptoms have highest impact on function in HD, moreover these symptoms affect female function and independence more than males. Results indicate that symptomatic treatment targeting motor symptoms is needed to improve HD function and QoL.

PECULIARITY OF THE INFANTRATED TRAUMATIC EXPERIENCE STRUCTURE IN DEMOBLIZED PARTICIPANTS OF MALAYSIA ACTIONS IN UKRAINE WITH POSTSTRESS PSYCHOLOGICAL DEZADAPTATION

Problem definition. The challenge of psychotherapeutic work with post-stress psychological disadaptation among military men in Ukraine is the resistance to it, and the polyparameterization of approaches for treatment makes this situation even more ambiguous. In the therapeutic literature (Kocharyan O. S., Yermoshin A.F.) the features of the psychotraumatic experience of traumatic feelings are described, but emotional schemes of traumatic experiences associated with PTSD-functioning are not characterized. [1-2] Problem analysis. In the scientific literature there are fragmentary results of theoretical and empirical studies regarding the traumatic experience of soldiers with operational record. From our point of view, there is a constructive idea of the emotional scheme, which is based on the concept of procedural and experimental psychotherapy by L. Greenberg, R. Elliott. [3] The purpose of the study is to determine the specificity of the structure concerning the traumatic experience of the military men in the Armed Forces of Ukraine - members of the ATO combat operations in Ukraine with signs of PTSD that have survived various types of infantile traumas. The research methods are the “Five Traumas” test (by L. Burbo) and the universal semantic differential (SD). To have a mathematical and statistical treatment, the criterion φ is the Fisher's transformation and the coefficient of rank correlation (τ-Kendal). Description of the sample. Two groups of 100 middle-aged men with and without signs of PTSD, who are soldiers of the Armed Forces of Ukraine - members of the combat zone for the ATO (groups 1 and 2). Conclusions. PTSD soldiers have such traumas as: abandonment, humiliation and injustice that potentiate one another. Contamination of trauma at the semantic level indicates the existence of a phenomenon of semantic adhesion in these military men.

Stability of cognitive development during the first five years of life in relation to heavy metal concentrations in umbilical cord blood: Mothers' and Children's Environmental Health (MOCEH) birth cohort study

The objective of this study was to investigate stability of cognitive development during the first five years of life in relation to heavy metal concentrations in umbilical cord blood in Korean children. This research is part of the Mothers' and Children's Environmental Health (MOCEH) study, a multi-center prospective birth cohort study of pregnant women in Korea who were recruited from 2006 to 2010. We analyzed the complete follow-up data of children who were 5years-old in 2016. We measured lead, mercury, and cadmium levels in the umbilical cord blood of 251 children, and analyzed them, for whom neurodevelopmental data were available. We determined stability of cognitive development scores using three methods. First, we used partial correlation analyses to examine the stability of cognitive development at each measurement time. Second, we used Cramer's V to investigate the magnitude and direction of changes in cognitive development scores at each follow-up period among three groups (high, medium, and low scores). The results showed that cognitive development scores measured at the closest times had the strongest correlations, and the stability of cognitive development scores increased with age, from 6 to 60months. Groups at the extreme ends of cognitive development (high or low scores) had more stable scores, and this tendency was also stronger in infants >24months-old. The stability of cognitive development was unrelated to the umbilical cord level of heavy metals, based on analysis with Fisher's transformation. In conclusion, the present study showed that the cognitive development scores in a cohort of infants (6 to 60months-old) were stable.

AMYLOID-BETA MODULATES CEREBRAL METABOLIC NETWORK IN RATS AND HUMANS

The amyloid hypothesis proposes that the amyloid pathology affects a series of downstream AD pathophysiology; changes in the brain metabolism, aggregation of neurofibrillary tangles, dysfunctional network, structural changes, and cognitive decline. This is supported by the typical pattern of amyloid-beta (Aβ) deposition that overlaps with the regional hypometabolism based on FDG-PET. Felix et al. have reported abnormal metabolic network in MCI Aβ+ individuals compared to Aβ- individuals. However, the interregional association between Aβ and FDG as well as interregional metabolic network (IMN) is still elusive. Here, we used Alzheimer's disease neuroimaging initiative (ADNI) database and McGill-R-Thy1-APP (Tg) to investigate the difference in IMN between Aβ+ and Aβ-. Furthermore, we characterized the difference in interregional association between Aβ and metabolism (IAMN) between Aβ+ and Aβ-. A total of 392 subjects from ADNI cohort (228 CN- = Aβ-, 164 MCI+ = Aβ+) was used and 17 (7 WT = Aβ-, 10 Tg = Aβ+) were used for this study. The ROC-based Aβ cut-off (1.286) was used to characterize CN- = Aβ- or MCI+ = Aβ+ from CN (287) and AD (176). Human IMN was generated based on the 201 nodes in 228 CN- and 164 MCI+. Rat IMN was generated based on 61 nodes in 7 WT and 10 Tg. The same regions were used to generate IAMN. Fisher's Z-transformation is applied to compare the network association between CN- and MCI+ as well as WT and Tg. MCI+ showed greater association compared to CN- in hippocampus, medial and lateral temporal cortex, superior parietal cortex, and fornix in IMN. Similarly, Tg showed greater association compared to WT in basal temporal cortex, parietotemporal cortex, and hypothalamus in IMN. Furthermore, regional Aβ association in lateral frontal cortex, lateral temporal cortex, and PCC/Precuneus in IMN metabolism were greater in MCI+ compared to CN-. Analogous regional Aβ associations were greater in Tg compared to WT in IMN.

AMYLOID-BETA MODULATES CEREBRAL METABOLIC NETWORK IN RATS AND HUMANS

The amyloid hypothesis proposes that the amyloid pathology affects a series of downstream AD pathophysiology; changes in the brain metabolism, aggregation of neurofibrillary tangles, dysfunctional network, structural changes, and cognitive decline. This is supported by the typical pattern of amyloid-beta (Aβ) deposition that overlaps with the regional hypometabolism based on FDG-PET. Felix et al. have reported abnormal metabolic network in MCI Aβ+ individuals compared to Aβ- individuals. However, the interregional association between Aβ and FDG as well as interregional metabolic network (IMN) is still elusive. Here, we used Alzheimer's disease neuroimaging initiative (ADNI) database and McGill-R-Thy1-APP (Tg) to investigate the difference in IMN between Aβ+ and Aβ-. Furthermore, we characterized the difference in interregional association between Aβ and metabolism (IAMN) between Aβ+ and Aβ-. A total of 392 subjects from ADNI cohort (228 CN- = Aβ-, 164 MCI+ = Aβ+) was used and 17 (7 WT = Aβ-, 10 Tg = Aβ+) were used for this study. The ROC-based Aβ cut-off (1.286) was used to characterize CN- = Aβ- or MCI+ = Aβ+ from CN (287) and AD (176). Human IMN was generated based on the 201 nodes in 228 CN- and 164 MCI+. Rat IMN was generated based on 61 nodes in 7 WT and 10 Tg. The same regions were used to generate IAMN. Fisher's Z-transformation is applied to compare the network association between CN- and MCI+ as well as WT and Tg. MCI+ showed greater association compared to CN- in hippocampus, medial and lateral temporal cortex, superior parietal cortex, and fornix in IMN. Similarly, Tg showed greater association compared to WT in basal temporal cortex, parietotemporal cortex, and hypothalamus in IMN. Furthermore, regional Aβ association in lateral frontal cortex, lateral temporal cortex, and PCC/Precuneus in IMN metabolism were greater in MCI+ compared to CN-. Analogous regional Aβ associations were greater in Tg compared to WT in IMN.

An Interval Estimation of Pearson’s Correlation Coefficient by Bootstrap Methods

In this paper, we compare three confidence intervals for Pearson’s correlation coefficient which are Fisher’s transformation, standard bootstrap and percentile bootstrap methods. The performance of these confidence intervals is considered by the coverage probability and the average width. Monte Carlo simulation results for generating non-normal distribution show that the percentile bootstrap confidence interval is the best method, when the distribution is a uniform distribution and the sample sizes are larger than or equal to 50. For the logistic and Laplace distributions, the percentile bootstrap method is the most efficiency method when the sample sizes are larger than or equal to 200 and the correlation coefficients are at least 0.5. However, the Fisher method gives the best confidence interval when the correlation coefficients are 0.2.

Accuracy of predictive ability measures for survival models.

One aspect of an analysis of survival data based on the proportional hazards model that has been receiving increasing attention is that of the predictive ability or explained variation of the model. A number of contending measures have been suggested, including one measure, R2 (β), which has been proposed given its several desirable properties, including its capacity to accommodate time-dependent covariates, a major feature of the model and one that gives rise to great generality. A thorough study of the properties of available measures, including the aforementioned measure, has been carried out recently. In that work, the authors used bootstrap techniques, particularly complex in the setting of censored data, in order to obtain estimates of precision. The motivation of this work is to provide analytical expressions of precision, in particular confidence interval estimates for R2 (β). We use Taylor series approximations with and without local linearizing transforms. We also consider a very simple expression based on the Fisher's transformation. This latter approach has two great advantages. It is very easy and quick to calculate, and secondly, it can be obtained for any of the methods given in the recent review. A large simulation study is carried out to investigate the properties of the different methods. Finally, three well-known datasets in breast cancer, lymphoma and lung cancer research are given as illustrations. Copyright © 2017 John Wiley & Sons, Ltd.

Bayesian discriminant analysis of lithofacies integrate the Fisher transformation and the kernel function estimation

The accurate identification of lithofacies is indispensable for reservoir parameter prediction. In recent years, the application of multivariate statistical methods has gained more and more attention in petroleum geology. In terms of the identification for lithofacies, the commonly used multivariate statistical methods include discriminant analysis and cluster analysis. Fisher and Bayesian discriminant analyses are two different discriminant analysis methods, which include intrinsic advantages and disadvantages. Given the discriminant efficiency of different methods, calculation cost, difficulty in the degree of determining the parameters, and the ability to analyze statistical characteristics of data, we put forward a new method combined with seismic information to classify reservoir lithologies and pore fluids. This method integrates the advantages of Fisher discrimination, the kernel function, and Bayesian discrimination. First, we analyze training data and search a projection direction. Then, data are transformed through Fisher transformation according to this direction and different kinds of facies can be distinguished more efficiently by exploiting transformed data than by using primitive data. Subsequently, using the kernel function estimates the conditional probability density function of the transformed variable. A classifier is constructed based on Bayesian theory. Then, the pending data are input to the classifier and the solution whose posteriori probability reaches the maximum is extracted as the predicted result at each grid node. An a posteriori probability distribution of predicted lithofacies can be acquired as well, from which interpreters can evaluate the uncertainty of the results. The ultimate goal of this study is to provide a novel and efficient lithofacies discriminant method. Tests on model and field data indicate that our method can obtain more accurate identification results with less uncertainty compared with conventional Fisher approaches and Bayesian methods.

Body frame size in school children is related to the amount of adipose tissue in different depots but not to adipose distribution.

The main aim of this study was to test the hypothesis that body frame size is related to the amount of fat in different adipose tissue depots and to fat distribution in schoolchildren. Children aged between 5 and 10 years were included in this cross-sectional study (n = 565). Body frame size, adiposity markers (anthropometric, skinfolds thickness, and ultrasound measures), and fat distribution indices were analyzed. Correlation coefficients adjusted by reliability were estimated and analyzed by sex; the significance of the difference between two correlation coefficients was assessed using the Fisher z-transformation. The sample included primarily urban children; 58.6% were normal weight, 16.1% overweight, 19.6% obese, and the rest were underweight. Markers of subcutaneous adiposity, fat mass and fat-free mass, and preperitoneal adiposity showed higher and significant correlations with the sum of the biacromial + bitrochanteric diameter than with the elbow diameter, regardless of sex. The fat distribution conicity index presented significant but weak correlations; and visceral adipose tissue, hepatic steatosis, and the waist-for-hip ratio were not significantly correlated with body frame size measures. Body frame size in school children was related to the amount of adipose tissue in different depots, but not adipose distribution. More studies are needed to confirm this relationship and its importance to predict changes in visceral fat deposition during growth.

Classifiers as a model-free group comparison test

The conventional statistical methods to detect group differences assume correct model specification, including the origin of difference. Researchers should be able to identify a source of group differences and choose a corresponding method. In this paper, we propose a new approach of group comparison without model specification using classification algorithms in machine learning. In this approach, the classification accuracy is evaluated against a binomial distribution using Independent Validation. As an application example, we examined false-positive errors and statistical power of support vector machines to detect group differences in comparison to conventional statistical tests such as t test, Levene's test, K-S test, Fisher's z-transformation, and MANOVA. The SVMs detected group differences regardless of their origins (mean, variance, distribution shape, and covariance), and showed comparably consistent power across conditions. When a group difference originated from a single source, the statistical power of SVMs was lower than the most appropriate conventional test of the study condition; however, the power of SVMs increased when differences originated from multiple sources. Moreover, SVMs showed substantially improved performance with more variables than with fewer variables. Most importantly, SVMs were applicable to any types of data without sophisticated model specification. This study demonstrates a new application of classification algorithms as an alternative or complement to the conventional group comparison test. With the proposed approach, researchers can test two-sample data even when they are not certain which statistical test to use or when data violates the statistical assumptions of conventional methods.

Comparison of readout‐segmented and conventional single‐shot for echo‐planar diffusion‐weighted imaging in the assessment of kidney interstitial fibrosis

To compare readout-segmented echo-planar imaging (EPI) (RESOLVE) to single-shot EPI (ss-EPI) diffusion-weighted imaging (DWI) for the assessment of renal interstitial fibrosis. A phantom, eight healthy volunteers (under 30 years to avoid age-fibrosis related) and 27 chronic kidney disease (CKD) patients (scheduled for kidney biopsy) were scanned (at 3T) with ss-EPI and 5-shot RESOLVE DWI (resolution: 2 × 2 × 5 mm3 , 10 b-values). The cortico-medullary difference for each DW parameter from a monoexponential fit (ΔADC) or, segmented biexponential fit (ΔD, ΔD*, ΔFp ) were compared between both sequences. A fibrosis threshold of 40% was defined to separate all 35 subjects into low and high fibrosis groups. The linear relationship between DW parameters and percentage fibrosis (up to 80%) from Masson trichrome was assessed with the Pearson product-moment correlation coefficient. Fisher Z-transform was used for R2 correlation comparison. A coefficient of variation between ADCs of 3% was measured between both sequences in the phantom. In healthy volunteers, no significant difference was measured for all DW parameters. Both sequences separated low to high level of fibrosis with a significant decrease of ΔADC (RESOLVE P = 3.1 × 10-6 , ss-EPI P = 0.003) and ΔD (RESOLVE P = 8.2 × 10-5 , ss-EPI P = 0.02) in the high level of fibrosis. However, RESOLVE ΔADC had a stronger negative correlation (P = 0.04 for R2 comparison) with fibrosis than ss-EPI ΔADC (RESOLVE R2 = 0.65, P = 5.9 × 10-9 , ss-EPI R2 = 0.29, P = 8.9 × 10-4 ). ΔD (RESOLVE) was correlated (moderately) with fibrosis (R2 = 0.29, P = 9.2 × 10-4 ); however, ΔD* and ΔFp did not show, in our population, a significant correlation with interstitial fibrosis (0.01 < R2 < 0.08). ΔADC derived from both sequences correlated with fibrosis. ΔADC from RESOLVE showed better correlation with fibrosis than ΔADC from ss-EPI and therefore has potential to monitor CKD. 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1631-1640.