Individual Dissimilarity Research Articles

The diagnostic role of acceleration time measurement in patients with classical low flow low gradient aortic stenosis with reduced left ventricular ejection fraction

Abstract Funding Acknowledgements Type of funding sources: None. Background Low-flow, low-gradient (LF-LG) AS can occur with a reduced or preserved left ventricular ejection fraction (LVEF) and is difficult to diagnose in either case(1). The main challenge is to distinguish between true severe and pseudo-severe stenosis. Dobutamine stress echocardiography (DSE) is recommended for the distinction of stenosis severity and LV flow reserve in classical LF-LG AS(2). Individual dissimilarities can be seen in the DSE results depending on the severity of the AS and LV afterload mismatch and/or on the existence of accompanying cardiomyopathy(3). One-third of the classical LF- LG AS with reduced LVEF patients do not have LV flow reserve (an increase of less than 20% in SV during DSE)(2). This patient group with an indeterminate DSE result has high surgical risk, and additional examinations are always required(4). Purpose The aim of our study was to evaluate the role of Acceleration time (AT), Ejection time (ET), and AT/ET ratio in predicting DSE outcome in classical LF-LG AS patients with reduced EF, and to distinguish between true and pseudo AS to determine the cut-off for AT which can be a useful evalu- ation method in clinical practice. Methods Sixty-seven classical LF-LG AS with reduced LVEF patients who underwent dobutamine stress echocardiography (DSE) were included in the study. Patients with ventricular arrhythmia and pace rhythm, moderate and severe mitral stenosis, severe aortic insufficiency, and paradoxical LF-LG AS patients were excluded. According to DSE results, all patients were divided into two groups; true AS and pseudo-severe AS. Aortic valve calcium score was measured in patients with inconclusive DSE results. AT and other ejection dynamics (ET and AT/ET) were calculated by taking baseline echocardiographic records into account for all patients(1,5). The predictive power of AT and other ejection dynamics were evaluated to estimate true and pseudo-severe AS. Results According to DSE results, out of 67 patients, 44 (65.7%) was diagnosed as true severe AS. There was a statistically significant relation between baseline AT and true AS [adjusted OR 4.47 (95% CI 1.93–10.4), p = 0.001]. The best cutoff value of AT was measured as 100 msec according to the Youden index. This value had a sensitivity value of 77%, specificity value of 87%, positive predictive value of 92%, and a negative predictive value of 67%. Conclusion In conclusion, the biggest difference of our study from the other studies in the literature is that we only included LF-LG AS patients with reduced EF in our study. Additionally, the study assesses the predictive strengths of ejection dynamics, one by one, regarding DSE results, and therefore, assesses role of ejection dynamics role to distinguish true and pseudo severe AS. As a result of our analysis, AT has a diagnos- tic role in the determination of true severe AS. Large-scale studies are needed to be carried out regarding true severe AS among LF LG AS patients with reduced LVEF.

Comparative analysis of structural and functional aspects of phytoene synthase from Meiothermus taiwanensis strain RP

PurposeThe aim of this study is the in silico characterization of the structure and function of the phytoene synthase (PSY) of a red carotenoid producing thermophile Meiothermus taiwanensis strain RP with a comparative approach.MethodsPSYs from M. taiwanensis strain RP and other groups of thermophilic, mesophilic and psychrophilic bacteria, plants, protozoa, and algae were analyzed by ExPASy ProtParam, NCBI Conserved Domain Search, SOPMA, PSIPRED, Robetta server, ProQ, and QMEAN, with the superposition of 3-D structures in PyMOL.ResultsRP PSY shows the highest (97.5 %) similarity with M. ruber and the lowest with the psychrophile Gelidibacter algens (36.7 %). The amino acid sequence of RP PSY is one of the shortest, with 275 residues. The instability index of RP PSY is much lower compared with plant sequences. Alanine, arginine, glycine, and leucine residues are the highest in Meiothermus sp., and they have a high amount of alpha-helix. Most of the 32 active site residues are conserved in all the sequences. However, some residues are more prone to substitutions in other PSYs except M. ruber. The three-dimensional structures of M. taiwanensis strain RP, Gelidibacter algens, Thermus thermophiles, Meiothermus ruber, and Brassica napus PSYs were homology modeled, validated, and submitted to Protein Model Databank. The superposition of the 3-D structures shows that their active site region structure is identical.ConclusionRP PSY is one of the most stable PSYs and knowledge of its individual properties, similarities, and dissimilarities with other PSYs may be useful for genetic engineering and purification of the protein for improved carotenoid production.

Gender and age classification using a new Poincare section-based feature set of ECG

In the medicine, the implication of individual differences has frequently been emphasized. Gender- and age-related differences can be mentioned as the most important individual parameters. On the other hand, electrocardiogram (ECG) signals are the subject of these differences. However, limited information is available regarding these individual dissimilarities in ECG dynamics. This study was aimed to evaluate gender and age differences by means of novel Poincare section indices. Our focus was to detect and classify dynamical behaviors of the ECG trajectories using three binary classification strategies: (1) gender-, (2) age-, (3) gender- and age-based classification. After constructing the 2D phase space of ECG, linear Poincare sections in distinct angles were developed and some geometric indices were extracted. The effect of delayed phase space on ECG measures was also inspected. We tested our algorithm on 79 healthy subjects. Using support vector machine, the maximum correct rate of 93.33% was achieved for the gender- and age-based classification strategies. Considering the information of both age and gender, the highest rate was 94.66%. The best results were achieved with delays of 5 and 6. In conclusion, our results showed that basin geometry of the ECG phase states is affected by individual differences.

Fast Embedding for JOFC Using the Raw Stress Criterion

ABSTRACTThe joint optimization of fidelity and commensurability (JOFC) manifold matching methodology embeds an omnibus dissimilarity matrix consisting of multiple dissimilarities on the same set of objects. One approach to this embedding optimizes the preservation of fidelity to each individual dissimilarity matrix together with commensurability of each given observation across modalities via iterative majorization of a raw stress error criterion by successive Guttman transforms. In this article, we exploit the special structure inherent to JOFC to exactly and efficiently compute the successive Guttman transforms, and as a result we are able to greatly speed up the JOFC procedure for both in-sample and out-of-sample embedding. We demonstrate the scalability of our implementation on both real and simulated data examples.

Does Demographic Dissimilarity Matter for Perceived Inclusion? Evidence From Public Sector Employees

This study examines the relationship between individual dissimilarity and perceptions of organizational inclusion. Data from a national survey of public agencies conducted in Florida and Texas show that gender dissimilarity is negatively associated with perceptions of inclusion and the negative relationship is more acute for men than for women. In contrast, tenure dissimilarity is positively related to perceptions of inclusion and this positive association is more acute for those with longer tenure than for those with shorter tenure. These results suggest that the effect of dissimilarity on the perception of inclusion depends on both the observability of individual-level characteristics and the status of the demographic group. In particular, dissimilarity along characteristics that are easily observable (such as gender) is more likely to influence perceptions of inclusion and dissimilarity is more influential for higher status groups (such as men or long-tenured employees).

Characteristic of Ionospheric foF2 and Solar Indices during the 23rd Solar Cycle over High Latitude Station, Syowa, Antarctica

The behavior and dynamics of ionosphere are completely dependent on the solar activity. We have investigated the long term variability of ionospheric parameter foF2 with corresponding changes in the solar activity during the 23rd solar cycle. The variation of the critical frequency of ionospheric foF2 at Syowa Station Antarctica, (69°S, 39°E) is examined with four different solar activity indices characterizing the long term variability of solar activity wise Flare Index, relative sunspot number (Rz), solar flux F10.7 cm and CME occurrence index. We compared the dependency of foF2 and other solar activity indices on each other by using linear correlation investigation, and showed the qualitative similarity of the ionospheric foF2 with the solar indices. We notice that hysteresis of foF2 is lower for the growing branches of the solar cycle. The individual dissimilarity of critical frequency foF2 demonstrated the dependency on the solar cycle but this variation was different during the months, which depended on solar activity and polar ionospheric behavior. The peak to peak variation between monthly average of critical frequency foF2 and solar indices parameter is evidence for the absolute dependency for each other. The linear correlation between the solar indices and foF2 is very strong during the climbing and downward branches of the solar cycle. However the incline of their linear fits shows variations from index to index.

Use of morpho-agronomic traits and DNA profiling for classification of genetic diversity in papaya

We examined the genetic diversity of papaya (Carica papaya) based on morpho-agronomic and molecular data. Twenty-seven genotypes grown in Brazil were analyzed with 11 AFLP primer combinations, 23 ISSR markers, 22 qualitative, and 30 quantitative descriptors. For the joint analyses, we used the Gower algorithm (Joint Gower) and the average value of the individual dissimilarity matrix for each type of data (Average-Joint Gower); 359 AFLP and 52 ISSR polymorphic bands were found. Approximately 29.2 and 7.7% of the AFLP and ISSR bands, respectively, were genotype-specific and may therefore be used for papaya variety protection. Although there was a significant correlation between the qualitative and quantitative descriptor dissimilarity matrices (r = 0.43), the morpho-agronomic data were not highly correlated with the molecular data. Moreover, correlation between AFLP and ISSR dissimilarity matrices was nearly null (r = -0.01). Joint Gower analysis of all data showed high correlations, especially for AFLP markers, most likely due to the larger number of bands, generating a strong bias in the diversity estimates. The Average-Joint Gower analysis allowed a better balance between the correlations for the continuous and the discrete variables. The results generated by clustering analysis distinguished 5 genetically distinct groups. While we found that papaya genotypes are significantly variable for many traits, we observed that Average-Joint Gower analysis allowed for genotype clustering based on the most widely used criterion for classifying papaya genotypes, which is fruit type ('Formosa' or 'Solo'). This information helps provide an accurate estimate of the genetic diversity and structure of papaya germplasm, which will be used for further breeding strategies.

Chemical Differences Between Voided and Bladder Urine in the Aye‐Aye (Daubentonia madagascariensis): Implications for Olfactory Communication Studies

Urine serves a communicative function in many mammalian species. In some species, the signaling function of urine can be enhanced by the addition of chemical compounds from glands along the distal portion of the urogenital tract. Although urine marking is the main mode of chemical communication in many primate species, there has been no study of the contribution of urogenital secretions to the chemical complexity of primate urine. Here, we compared the chemical composition of bladder urine versus voided urine in the aye-aye, Daubentonia madagascariensis, a strepsirrhine primate that relies on urine in intraspecific communication. Both types of urine, collected from each of 11 aye-ayes representing both sexes of varying adult ages, underwent headspace analysis via gas chromatography and mass spectrometry. Although the average number of compounds was similar in bladder and voided urine, 17% of the compounds detected occurred exclusively in voided urine (but only in a subset of individuals). An overall measure of chemical complexity (using a nonmetric multidimensional scaling analysis) showed that both types of urine were chemically different at the individual level. There was no apparent sex or age differences in the chemical components found in aye-aye urine. Nonetheless, the individual dissimilarities between bladder urine and voided urine indicate chemical contributions from structures along the urogenital tract and offer further support for the relevance of urinary communication in the aye-aye.

Inconsistencies between theory and methodology: a recurrent problem in ordination studies

AbstractContextA historical review of ordination studies is presented with particular reference to the pioneering contributions of the late Prof. I. Noy‐Meir and their continuing relevance.Issues(1) Comparisons of ordination methods are often confounded by differences in the methodological algorithm, dissimilarity measure used and the data standardization employed. (2) Artificial data where ‘truth’ is known offer a means of evaluating ordination approaches but are highly sensitive to the ecological model assumed. (3) Data standardization is frequently used but its influence on ordination is poorly understood and lacks theoretical justification.ReviewHistorically, the above issues have been continually raised since the first use of artificial data by Swan in 1970 to demonstrate the ‘horseshoe distortion’. Three distinct conceptual models have been used to generate artificial data, yet no consensus on their suitability has emerged since they were first used in the mid‐1970s. Comparative studies had, by the late 1980s, shown that some approaches recovered ‘ecological truth’ better than others. Differences between comparative studies in conceptual models, nature of the data matrices used, different dissimilarity measures, ordination algorithms and evaluations methods limited acceptance of this conclusion. Data standardization alters the properties of the vegetation data matrix. Yet little is known regarding the influence on ordination results of the collective vegetation properties stand abundance, dominance or species richness, which are altered by standardization.Recent developmentsKnowledge of the properties of individual dissimilarity measures and ordination algorithms has increased; a few new methods have emerged. Pragmatism of the type ‘this method gives me useful answers so I do not need to use a better method’ is common. Tests of conceptual models are now occurring based on species distribution modelling.ConclusionsA consensus is emerging that non‐metric multidimensional scaling and dissimilarity measures such as the Bray–Curtis coefficient should be used in preference to correspondence analysis methods based on the χ2 dissimilarity measure. Absence of a comprehensive model of vegetation composition is limiting ordination as a method of community analysis. Inconsistencies between different ordination methods and ecological models first recognized in the 1970s remain today.

Group mate absence, dissimilarity, and individual absence: Another look at “monkey see, monkey do”

In this study, we examined whether the alignment of individual and group absence depended on an individual's similarity or dissimilarity with his or her group mates. The study hypotheses were tested with organizational data, involving 1382 employees from 181 work groups. Our criterion was individual absence frequency, observed over a 12-month period. Dissimilarity indices fororganizational tenure and union affiliation were computed from organizational records. We found that the relation between group mate absence and individual absence was moderated by dissimilarity with respect to union affiliation (but not tenure dissimilarity), such that those with low union dissimilarity scores were more likely to align their absence behaviour with that of their group mates.

XPac dissimilarity parameters as quantitative descriptors of isostructurality: the case of fourteen 4,5′-substituted benzenesulfonamido-2-pyridines obtained by substituent interchange involving CF3/I/Br/Cl/F/Me/H

Crystal structures of fourteen 4,5′-substituted benzenesulfonamido-2-pyridines, with tautomeric forms R1–C6H4–SO2–NC5NH4–R2 or R1–C6H4–SO2–NH–C5NH3–R2, and with R1 = CF3, I, Br, Cl, Me, F, H and R2 = CF3 or I are reported. Comparisons carried out with the program XPac show that all investigated structures display a common 3D arrangement of N–H⋯N bonded centrosymmetric dimers. This isostructural series is exceptional in its completeness and in the diversity of the substituents involved. Accordingly, the XPac dissimilarity index x, a measure of how far two structures deviate from perfect geometrical similarity, varies from 0.9 for the interchange R1 = Br → Cl to 9.5 for the simultaneous interchange of R1 = I → H and R2 = CF3 → I. XPac plots of individual dissimilarity parameters have been used to elucidate details of geometrical similarities and differences between structures. This indicated that the geometry is preserved most closely within bc-layers that are composed of 1D slipped stacks of N–H⋯N bonded dimers, with interlayer van der Waals interactions being dominated by R1⋯R2 contacts. The main mode of geometrical adjustment for the size of R1 is a parallel shift of neighbouring layers against one another in the direction perpendicular to the layer plane, whilst the relative orientations of molecules within each layer are altered to a much smaller extent, even for those structure pairs representing R1 substituents that are very different in size. This study shows that the ability of two compounds to crystallise in fundamentally the same crystal structure depends not only on how much their molecules differ in shape but also, critically, on the specific tolerance characteristics of the crystal packing arrangement concerned. As a comparison with the present study, dissimilarity indices are reported for a set of 24 isostructural 4,4′-substituted benzenesulfonamidobenzenes previously subjected to XPac analysis.

Quantifying the relevance of intraspecific trait variability for functional diversity

Summary1. Intraspecific trait variability is a crucial, often neglected, component of functional diversity (FD) in ecological communities. In particular, uncertainty remains as to the importance of intraspecific variability in the quantification of FD.2. To explore this uncertainty, we propose two methods addressing two critical and complementary, but largely unexplored, questions: (i) what is the extent of within‐ vs. between‐species FD in different communities? and (ii) to what extent is the response of FD to environment because of compositional turnover vs. intraspecific trait variability across habitats? The methods proposed to address these questions are built on a variance partitioning approach and have the advantage of including species relative abundance, therefore taking into account species dominance and rarity. For each of the questions, we illustrate one dedicated case study in semi‐natural grasslands with associated sampling strategies.3. The decomposition of total community variance into within‐ vs. between‐species effects can be implemented in a manner similar to the decomposition of quadratic entropy on pairwise individual dissimilarity. The approach can be applied with single and multiple traits, although it proves more informative for single traits. It can prove particularly useful when assessing the role of different sources of trait variability in the assembly of communities.4. The assessment of the relative contribution of intraspecific trait variability and species turnover to the response of FD to environment is based on a variance partitioning comparing FD indices computed (i) either using individuals measured in a specific habitat alone (FDhabitat) or (ii) all individuals measured across different habitats (FDfixed). This approach provides a more complete understanding of the response of FD to environment.5. We further propose a guide to apply these two methods and to choose the most suitable method for intraspecific trait measurements. Assessing the role of intraspecific trait variability should allow a more comprehensive understanding of the processes that link species and ecosystems.

Personal identity and perceived racial dissimilarity among college athletes.

The purpose of this study was to examine the influence of personal identity on the relationship between individual dissimilarity and subsequent outcomes. Data were collected from 271 student-athletes participating in a variety of National Collegiate Athletic Association sports. Results from structural equation modeling indicated that the relationship between actual racial dissimilarity and perceived racial dissimilarity was stronger for persons with a strong racial personal identity than for other athletes. Further analyses indicated that person-team fit mediated the relationship between perceived racial dissimilarity and satisfaction with the team. Results are discussed in terms of theoretical contributions and practical implications.

Turnover at the Top:: Demographic Diversity as a Determinant of Executive Turnover in The Netherlands

The current study examines diversity-related causes of executive turnover. Based on an integration of Schneider’s (1987) ASA model and Pfeffer’s (1983) organizational demography theory, it is hypothesized that individual demographic dissimilarity and team-level demographic heterogeneity are positively related to individual executive turnover. Results indicate that individual dissimilarity in age and TMT tenure are solid predictors of individual executive turnover. Furthermore, our test of cross-level hypotheses shows that a high degree of heterogeneity within the team does not increase the likelihood of individual executive turnover if individual dissimilarities are taken into account. The study reinforces the importance of top team demographic composition in explaining executive turnover.

No es como mí: Relational demography and conflict in a Mexican production facility

In recent years management scholars have conducted an array of studies on relational demography. Most of this research, however, has taken place in the USA. Also, few of these prior investigations have looked at the role of moderators. In an effort to begin addressing those gaps, this study assessed the relationship between individual demographic dissimilarity and conflict in a Central Mexican workplace; additionally, it examined the moderating role of supervisor facilitation. Data from 190 Mexican workers revealed that in this study, as in comparable US studies, conflict had a two‐dimensional structure consisting of task conflict and emotional conflict. Associations between relational demography and conflict, however, were not identical to those previously found in the USA. Individual dissimilarity in age was positively associated with emotional conflict, while individual dissimilarity in tenure was negatively associated with both task and emotional conflict. Supervisor facilitation moderated the relationships between tenure dissimilarity and conflict. These results suggest that greater attention to demography effects, as well as moderators of those effects, in Mexico is warranted.

Demographic Dissimilarity and Workplace Inclusion

This study examined the relationship between individual demographic dissimilarity from co‐workers and three indicators of inclusion by an organization: decision‐making influence, access to sensitive information, and job security. Data from 345 individuals in eight work units showed that individual dissimilarity in race and gender were negatively associated with inclusion, and the effect of race dissimilarity was more pronounced for whites than for non‐whites. In contrast, individual dissimilarity in tenure and education level were positively associated with inclusion, and these effects were more pronounced for those with greater tenure and greater education, respectively. Overall, the results suggest that whether being different hinders or helps organizational inclusion may depend on whether that difference is visible and whether it reflects job expertise. Further, they suggest that, when being different is a hindrance, it may be hardest on those who have traditionally been the majority in organizations.

Equally qualified but unequally perceived: Openness to perceived dissimilarity as a predictor of race and sex discrimination in performance judgments

AbstractA measure of individual dissimilarity openness, defined as openness toward individual differences, was developed and assessed as a predictor of rating bias toward minorities. Participants' openness to dissimilarity was assessed with the Ideal Employee Inventory (IEI), and two weeks later participants evaluated one of two job candidates based on information provided by an identical vitae and audiotaped sample lecture. The candidate was implied to be female Native American in the treatment group, but male Caucasian in the control group. It was hypothesized that the perceived minority candidate would be rated lower despite identical performance and vita, and that dissimilarity‐closed individuals, as indicated by high IEI scores, would be predictive of lower ratings of the minority candidate but not of the control candidate. Propositions regarding HRD practice, measurement, and research are presented.

INDIVIDUAL DEMOGRAPHIC DISSIMILARITY AND ORGANIZATIONAL INCLUSION: A FIELD INVESTIGATION.

This study examined the relationship between individual demographic dissimilarity and workplace inclusion. Results showed race and gender dissimilarity negatively affected inclusion, and these effects were stronger for whites and males. Tenure and education level dissimilarity positively affected inclusion, and these effects were stronger for those with greater tenure and education.

Organizational Demography in Japanese Firms: Group Heterogeneity, Individual Dissimilarity, and Top Management Team Turnover

Organizational Demography in Japanese Firms: Group Heterogeneity, Individual Dissimilarity, and Top Management Team Turnover

Some differences make a difference: Individual dissimilarity and group heterogeneity as correlates of recruitment, promotions, and turnover.

Schneider's (1987) attraction-selection-attrition model and Pfeffer's (1983) organization demography model were used to generate individual-level and group-level hypotheses relating interpersonal context to recruitment, promotion, and turnover patterns. Interpersonal context was operationalized as personal dissimilarity and group heterogeneity with respect to age, tenure, education level, curriculum, alma mater, military service, and career experiences. For 93 top management teams in bank holding companies examined over a 4-yr period, turnover rate was predicted by group heterogeneity. For individuals, turnover was predicted by dissimilarity to other group members, but promotion was not. Team heterogeneity was a relatively strong predictor of team turnover rates. Furthermore, reliance on internal recruitment predicted subsequent team homogeneity.