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PubMed2005

Convergence time for the linkage learning genetic algorithm.

This paper identifies the sequential behavior of the linkage learning genetic algorithm, introduces the tightness time model for a single building block, and develops the connection between the sequential behavior and the tightness time model. By integrating the first-building-block model based on the sequential behavior, the tightness time model, and the connection between these two models, a convergence time model is constructed and empirically verified. The proposed convergence time model explains the exponentially growing time required by the linkage learning genetic algorithm when solving uniformly scaled problems.

Algorithms↗

PubMed1995

On the distribution and convergence of feature space in self-organizing maps.

In this paper an analysis of the statistical and the convergence properties of Kohonen's self-organizing map of any dimension is presented. Every feature in the map is considered as a sum of a number of random variables. We extend the Central Limit Theorem to a particular case, which is then applied to prove that the feature space during learning tends to multiple gaussian distributed stochastic processes, which will eventually converge in the mean-square sense to the probabilistic centers of input subsets to form a quantization mapping with a minimum mean squared distortion either globally or locally. The diminishing effect, as training progresses, of the initial states on the value of the feature map is also shown.

Algorithms↗

PubMed1995

Regularized neural networks: some convergence rate results.

In a recent paper, Poggio and Girosi (1990) proposed a class of neural networks obtained from the theory of regularization. Regularized networks are capable of approximating arbitrarily well any continuous function on a compactum. In this paper we consider in detail the learning problem for the one-dimensional case. We show that in the case of output data observed with noise, regularized networks are capable of learning and approximating (on compacta) elements of certain classes of Sobolev spaces, known as reproducing kernel Hilbert spaces (RKHS), at a nonparametric rate that optimally exploits the smoothness properties of the unknown mapping. In particular we show that the total squared error, given by the sum of the squared bias and the variance, will approach zero at a rate of n(-2m)/(2m+1), where m denotes the order of differentiability of the true unknown function. On the other hand, if the unknown mapping is a continuous function but does not belong to an RKHS, then there still exists a unique regularized solution, but this is no longer guaranteed to converge in mean square to a well-defined limit. Further, even if such a solution converges, the total squared error is bounded away from zero for all n sufficiently large.

Mathematics↗

PubMed2004

Glycogen synthase kinase-3beta mediates convergence of protection signaling to inhibit the mitochondrial permeability transition pore.

Environmental stresses converge on the mitochondria that can trigger or inhibit cell death. Excitable, postmitotic cells, in response to sublethal noxious stress, engage mechanisms that afford protection from subsequent insults. We show that reoxygenation after prolonged hypoxia reduces the reactive oxygen species (ROS) threshold for the mitochondrial permeability transition (MPT) in cardiomyocytes and that cell survival is steeply negatively correlated with the fraction of depolarized mitochondria. Cell protection that exhibits a memory (preconditioning) results from triggered mitochondrial swelling that causes enhanced substrate oxidation and ROS production, leading to redox activation of PKC, which inhibits glycogen synthase kinase-3beta (GSK-3beta). Alternatively, receptor tyrosine kinase or certain G protein-coupled receptor activation elicits cell protection (without mitochondrial swelling or durable memory) by inhibiting GSK-3beta, via protein kinase B/Akt and mTOR/p70(s6k) pathways, PKC pathways, or protein kinase A pathways. The convergence of these pathways via inhibition of GSK-3beta on the end effector, the permeability transition pore complex, to limit MPT induction is the general mechanism of cardiomyocyte protection.

Animals↗

PubMed2006

A specific p47phox -serine phosphorylated by convergent MAPKs mediates neutrophil NADPH oxidase priming at inflammatory sites.

Neutrophil NADPH oxidase plays a key role in host defense and in inflammation by releasing large amounts of superoxide and other ROSs. Proinflammatory cytokines such as GM-CSF and TNF-alpha prime ROS production by neutrophils through unknown mechanisms. Here we used peptide sequencing by tandem mass spectrometry to show that GM-CSF and TNF-alpha induce phosphorylation of Ser345 on p47phox, a cytosolic component of NADPH oxidase, in human neutrophils. As Ser345 is located in the MAPK consensus sequence, we tested the effects of MAPK inhibitors. Inhibitors of the ERK1/2 pathway abrogated GM-CSF-induced phosphorylation of Ser345, while p38 MAPK inhibitor abrogated TNF-alpha-induced phosphorylation of Ser345. Transfection of HL-60 cells with a mutated p47phox (S345A) inhibited GM-CSF- and TNF-alpha-induced priming of ROS production. This event was also inhibited in neutrophils by a cell-permeable peptide containing a TAT-p47phox-Ser345 sequence. Furthermore, ROS generation, p47phox-Ser345 phosphorylation, and ERK1/2 and p38 MAPK phosphorylation were increased in synovial neutrophils from rheumatoid arthritis (RA) patients, and TAT-Ser345 peptide inhibited ROS production by these primed neutrophils. This study therefore identifies convergent MAPK pathways on Ser345 that are involved in GM-CSF- and TNF-alpha-induced priming of neutrophils and are activated in RA. Inhibition of the point of convergence of these pathways might serve as a novel antiinflammatory strategy.

Amino Acid Sequence↗

PubMed1989

Sex-related differences in spatial ability: more evidence for convergence.

Sex-related differences in spatial ability, favoring males, have frequently been reported in the literature. Recent analyses, however, have found indications of a convergence in the scores of men and women on spatial tests over the years. This research examined the evidence for such a secular trend in a German population using data of 18 samples that had completed the Cube Perspectives Test, a measure of spatial visualization ability. The largest effect size (d = .77) was found for a sample tested in 1978, the smallest difference (d = .38) was observed for a sample tested in 1987. There was a clear trend narrowing the sex-related differences; the correlation between the recency of the data and the respective d-value was -.926. The convergence of the scores of men and women proved to be stronger than in the previous studies.

Adolescent↗

PubMed1990

Convergence in world urbanization? A quantitative assessment.

"Cross-national data are used to explore the question of whether world urban patterns and processes are converging or diverging. We compare tabular data on overall percent urban, urban primacy, overurbanization, and urban bias across world-system strata and global regions. The evidence suggests continuing differences and little evidence for convergence. To determine whether world-system effects have causal efficacy, we conclude with a regression analysis. These results provide strong evidence for a world-system explanation of continuing differences in overall level of urbanization and urban primacy, and a developmentalist approach seems to explain persisting divergence in levels of urban bias."

Demography↗

PubMedDate not supplied

How convergence of research paradigms can improve research on diagnostic judgment.

The author's purpose is to urge the constructive convergence of two current judgment and decision-making research paradigms. He shows why the heuristics-and-biases approach and the lens-model approach should be placed in the context of two very different metatheories, the coherence metatheory and the correspondence metatheory. The differences between the two research paradigms thus become apparent; they speak to different problems and appeal to different criteria for evaluating performance. Bringing the two into a constructive relationship to one another, however, will not only double the store of knowledge regarding diagnostic judgment and decision making, but also enhance efforts to achieve a cumulative discipline. Isolating these research paradigms from one another--as is done now--stifles theoretical generality, fragments knowledge, and confuses medical decision makers. An example of how convergence can be achieved is provided.

Bias↗

PubMedDate not supplied

Assessing convergent validity of health-state utilities obtained using different scaling methods.

A number of empirical studies have attempted to assess the convergent validity of health-state utilities obtained using two or more scaling methods (standard gamble, time tradeoff, rating scale, magnitude estimation, equivalence technique, and willingness-to-pay). The data from these studies can be mapped onto an N x K matrix, where N and K are the numbers of respondents and health states, respectively, and each matrix cell consists of a pair of health-state utilities, one obtained using scaling method X and the other obtained using scaling method Y. The Pearson's rassessing convergent validity can then be computed as 1) the unraveled correlation over all N x K data pairs, 2) the mean within-respondent correlation, 3) the mean within-health-state correlation, or 4) the correlation of the across-respondents means. These four different ways of computing the correlation do not necessarily yield the same results. The appropriateness of each method of computing the correlation is considered.

Decision Support Techniques↗

PubMed2006

Finding common ground in team-based qualitative research using the convergent interviewing method.

Research councils, agencies, and researchers recognize the benefits of team-based health research. However, researchers involved in large-scale team-based research projects face multiple challenges as they seek to identify epistemological and ontological common ground. Typically, these challenges occur between quantitative and qualitative researchers but can occur between qualitative researchers, particularly when the project involves multiple disciplinary perspectives. The authors use the convergent interviewing technique in their multidisciplinary research project to overcome these challenges. This technique assists them in developing common epistemological and ontological ground while enabling swift and detailed data collection and analysis. Although convergent interviewing is a relatively new method described primarily in marketing research, it compares and contrasts well with grounded theory and other techniques. The authors argue that this process provides a rigorous method to structure and refine research projects and requires researchers to identify and be accountable for developing a common epistemological and ontological position.

Cooperative Behavior↗

PubMed2004

Convergent effects on cell signaling mechanisms mediate the actions of different neurobehavioral teratogens: alterations in cholinergic regulation of protein kinase C in chick and avian models.

Although the actions of heroin on central nervous system (CNS) development are mediated through opioid receptors, the net effects converge on dysfunction of cholinergic systems. We explored the mechanisms underlying neurobehavioral deficits in mouse and avian (chick, Cayuga duck) models. In mice, prenatal heroin exposure (10 mg/kg on gestation days 9-18) elicited deficits in behaviors related to hippocampal cholinergic innervation, characterized by concomitant pre- and postsynaptic hyperactivity, but ending in a reduction of basal levels of protein kinase C (PKC) isoforms betaII and gamma and their desensitization to cholinergic receptor-induced activation. PKCalpha, which is not involved in the behaviors studied, was unaffected. Because mammalian models possess inherent confounding factors from maternal effects, we conducted parallel studies using avian embryos, evaluating hyperstriatal nucleus (intermedial part of the hyperstriatum ventrale, IMHV)-related, filial imprinting behavior. Heroin injection to the eggs (20 mg/kg) on incubation days 0 and 5 diminished the post-hatch imprinting ability and reduced PKCg and bII content in the IMHV membrane fraction. Two otherwise unrelated agents that converge on cholinergic systems, chlorpyrifos and nicotine, elicited the same spectrum of effects on PKC isoforms and imprinting but had more robust actions. Pharmacological characterization also excluded direct effects of opioid receptors on the expression of imprinting; instead, it indicated participation of serotonergic innervation. The avian models can provide rapid screening of neuroteratogens, exploration of common mechanisms of behavioral disruption, and the potential design of therapies to reverse neurobehavioral deficits.

Animals↗

PubMed1977

Discriminant and convergent validity of the SCL-90 in psychiatric inpatients.

Examined the convergent and discriminant validity of the SCL-90 in a group of 113 psychiatric inpatients and determined the degree of reactivity to several common response sets. The nine SCL-90 dimensions were found to correlate with analogous measures from other tests, and thus showed convergent validity, but were also found to correlate with nonanalogous measures, an indication of low discriminant validity. In addition, the dimensions correlated with the three MMPI validity scales, suggesting their reactivity to response bias. These findings were interpreted as indicating that the SCL-90 has limited use with psychiatric inpatients at present, although it may be useful as a brief screening device for disposition and referral.

Journal Article↗

PubMed1986

The Body Esteem Scale: a convergent and discriminant validity study.

This research was intended to further establish convergent and discriminant validity for a recent Body Esteem Scale (BES) which measures different dimensions of body satisfaction in young adults. One hundred and fifty-four male and 193 female undergraduates completed the BES, the Body Consciousness Questionnaire (BCQ), the Self-Esteem Scale, and several questions pertaining to exercise, food intake, and attractiveness. Good convergent and discriminant validity was demonstrated by the Male Upper Body Strength and Physical Condition subscales and by the female Weight Concern, Physical Condition, and Sexual Attractiveness subscales.

Journal Article↗

PubMed1994

Assessment of childhood depression, anxiety, and aggression: convergent and discriminant validity of self-, parent-, teacher-, and peer-report measures.

Childhood depression, anxiety, and aggression assessment instruments were examined in a sample of 8- to 11-year-old elementary school children. A multitrait-multimethod design was used to evaluate self-, parent-, teacher-, and peer-report on each of the three traits. Results found the measures exhibited significant convergent and discriminant validity for both boys and girls. However, different patterns in convergence among the information sources emerged between boys and girls. Both the intercorrelations and the analyses of variance documented significant method variance. The implications of the high method variance or source bias in the assessment process are discussed. It is argued that investigators employ confirmatory factor analyses in evaluation of multitrait-multimethod data.

Aggression↗

PubMed1995

Differential convergence of self-report and informant data for multidimensional personality questionnaire traits: implications for the construct of negative emotionality.

Construct validation work on Tellegen's (1982) Multidimensional Personality Questionnaire (MPQ) resulted in further inferences about Negative Emotionality. Two hundred thirty-two students were rated by three knowledgeable informants, yielding a total of 928 participants. The median monotrait correlation of MPQ primary scores with summed observer ratings was .48, and all were significant, p < .01. These data show higher self-report to informant rating convergences in the Positive Emotionality (Extroversion) domain than in the Negative Emotionality (Neuroticism) domain. Furthermore, in the Negative Emotionality domain, peers, mothers, and fathers were not equivalent as classes of raters. Stress Reaction ratings showed uniformly lower levels of convergence with self-report (relative to Positive Emotionality traits) across all rater classes. For Alienation, peer and maternal ratings were comparable, but paternal ratings correlated significantly less with self-report scores than did maternal ratings. And finally, with Aggression, peer ratings correlated significantly higher with self-report than either maternal or paternal ratings. These findings, taken in the context of the literature, have implications for a hierarchical model of Negative Emotionality, support inferences about the display of cues of Negative Emotionality, and offer new cautions for rating-based assessment.

Journal Article↗

PubMed1999

The convergent validity of MMPI and Rorschach scales: an extension using profile scores to define response and character styles on both methods and a reexamination of simple Rorschach response frequency.

Past research indicated the convergence of Rorschach and MMPI scales may be a function of (a) simple Rorschach response frequency (R) or (b) complex response-character styles on both methods. In this study, new criteria were developed for defining the second assumption using F and K from the MMPI and R and Lambda from the Rorschach. Although substantially different from the factor criteria used previously (KS = .45 and .30), the new criteria still produced the expected pattern of correlations among MMPI and Rorschach scales. Averaged across 17 constructs, the new criteria produced strong validity coefficients for patients with similar styles (M composite r = .50), though they were less effective for patients with discordant styles (M composite r = -.27). It was also demonstrated that R by itself does not moderate convergent validity. Rather, statistical modeling with two sets of 300 random samples (a) demonstrated the prior findings related to R were the result of sampling error and (b) supported the general hypothesis that Rorschach and MMPI scales correlate to the extent response-character styles correlate. Implications are considered.

Adolescent↗

PubMed2000

A replication of Rorschach and MMPI-2 convergent validity.

We replicated prior research on Rorschach and MMPI-2 convergent validity by testing 8 hypotheses in a new sample of patients. We also extended prior research by developing criteria to include more patients and by applying the same procedures to 2 self-report tests: the MMPI-2 and the MCMI-II. Results supported our hypotheses and paralleled the prior findings. Furthermore, 3 different tests for methodological artifacts could not account for the results. Thus, the convergence of Rorschach and MMPI-2 constructs seems to be partially a function of how patients interact with the tests. When patients approach each test with a similar style, conceptually aligned constructs tend to correlate. Although this result is less robust, when patients approach each test in an opposing manner, conceptually aligned constructs tend to be negatively correlated. When test interaction styles are ignored, MMPI-2 and Rorschach constructs tend to be uncorrelated, unless a sample just happens to possess a correlation between Rorschach and MMPI-2 stylistic variables. Remaining ambiguities and suggestions for further advances are discussed.

Factor Analysis, Statistical↗

PubMed2001

Adjectival descriptions of personality disorders: a convergent validity study of the MCMI-III.

The responses to a 469-item list of adjectives (consensually validated by national experts as representing key descriptors for each personality disorder) from 202 male substance abusers in outpatient treatment were correlated with their responses to the MCMI-III, a frequently used test for the assessment of personality disorders. Results suggested good convergent validity for the interpersonal descriptive domain for the MCMI-III scales. The Histrionic scale had extremely high convergent validity.

Adult↗