Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “predictability of adaptation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,081 records · Page 60Linked to original sources
PubMed2002

The disappearance of prognostic factors in Hodgkin's disease.

The purpose of this conceptual (and somewhat provocative) article is to analyse the reasons for the disappearance of prognostic factors in Hodgkin's disease (HD) and to explore the consequences for further research from a biometrical point of view. The very concept of prognostic factors is about to resolve in HD. Prognostic factors gradually loose their predictive power as treatment is successfully adapted to the disease burden. Freedom from treatment failure and overall survival curves of patients in early, intermediate and advanced stages of HD are superimposable with the best current treatment protocols of the German Hodgkin's Lymphoma Study Group. This disappearance of prognostic factors in HD necessitates a certain conceptual remodelling. It's time to think quantitatively and bivariately, and we need to (i) synthesise existing 'prognostic' factors into a quantitative measure of disease burden or severity; (ii) develop a quantitative measure of treatment strength and (iii) relate these two quantities in nomogram curves indicating how much treatment a patient with a given disease burden requires to have, say, a 85%, 90% and perhaps 95% expected chance of cure.

Combined Modality Therapy↗
PubMed2006

Recent evolution of the human pathogen Cryptococcus neoformans by intervarietal transfer of a 14-gene fragment.

The availability of the whole-genome sequence from the 2 known varieties of the human pathogenic fungus Cryptococcus neoformans provides an opportunity to study the relative contribution of divergence and introgression during the process of speciation in a genetically tractable organism. At the genomic level, these varieties are nearly completely syntenic, share approximately 85-90% nucleotide identity, and are believed to have diverged approximately 18 MYA. Via a comparative genomic approach, we identified a 14-gene region (approximately 40 kb) that is nearly identical between the 2 varieties that resulted from a nonreciprocal transfer event from var. grubii to var. neoformans approximately 2 MYA. The majority of clinical and environmental var. neoformans strains from around the world contain this sequence obtained from var. grubii. This introgression event likely occurred via an incomplete intervarietal sexual cycle, creating a hybrid intermediate where mobile elements common to both lineages mediated the exchange. The subsequent duplication in laboratory strains of a fragment of this same genomic region supports evolutionary theories that instabilities in subtelomeric regions promote adaptive evolution through gene amplification and subsequent adaptation. Along with a more ancient predicted transfer event in C. neoformans and a recently reported example from Saccharomyces cerevisiae, these data indicate that DNA exchange between closely related sympatric varieties or species may be a recurrent theme in the evolution of fungal species. It further suggests that although evolutionary divergence is the primary force driving speciation, rare introgression events also play a potentially important role.

Chromosome Mapping↗
PubMedDate not supplied

Relationships between retrospective parent reports of developmental milestones and school adjustment at ages 10 to 12 years.

OBJECTIVE: The study's main purpose was to assess the extent to which retrospective parent reports of the child's achievement of early developmental milestones predicted later (fourth to sixth grade) adaptation to stress, and school adjustment and achievement, in a highly stressed urban sample. METHOD: Information about when children achieved key developmental milestones was obtained in individual parent interviews. Information about the child's current school adjustment and achievement was obtained from classroom teachers and school records. RESULTS: Factor analysis of a 12-item developmental milestone measure yielded an interpretable two-factor solution, i.e., motor and verbal milestones. Parents of stress-resilient, compared with stress-affected, children reported significantly earlier developmental milestone mastery by their offspring on both factor and total scores. Developmental factor milestone and total scores also related modestly to indicators of good school adjustment and academic achievement at ages 10 to 12 years. CONCLUSION: Delayed mastery of early developmental milestones may be a risk factor toward which preventive interventions can be gainfully targeted.

Achievement↗
PubMed2003

Inter-observer and intra-observer variability in hepatology.

OBJECTIVES: A determination of the inter-observer variability is an important step before determining diagnostic accuracy and requires a specific methodology and statistical tests. The aim of this study was to report the results, characteristics and methodological quality of agreement studies performed in hepatology. METHODS: A search of published studies yielded 42 that could be used in this evaluation: three were clinical studies, 11 were in the field of endoscopy, 12 in histopathology and 16 in radiology. The studies were described with a grid of 28 items and evaluated with a quality score (QUAS; maximum, 35) including 22 items. RESULTS: The following agreement level was noted: intra-observer > inter-observer > inter-centre. The following signs had good agreement. Endoscopy: size and red signs of oesophageal varices; histopathology: cirrhosis, fibrosis and steatosis; Doppler: mean portal vein and superior mesenteric artery velocities, hepatic artery area and perfusion indexes. Frequent methodological weaknesses were noted. The real agreement (such as the kappa index excluding chance), and the prevalence of signs and biases were rarely assessed. Standardized observations (67% of the studies), blind assessment (48%), simultaneous observations (7%), and the recording technique were not frequently used. The mean QUAS was 13 +/- 6 with 17 +/- 4 in histopathology versus 11 +/- 6 in radiology (P < 0.05). Using multiple regression, four variables independently predicted the QUAS with R2 = 0.77: adapted tests, multiple observations, intra-class correlation coefficient and agreement proportion. CONCLUSIONS: Methodology was often insufficient. Agreement is often measured under biased conditions. Some areas were not or were rarely studied, e.g., biology and ultrasound. The agreement and QUAS were often poor, suggesting the need for studies with improved observation and methodological quality of agreement.

Esophageal and Gastric Varices↗
PubMed2003

Experimental manipulation of egg carotenoids affects immunity of barn swallow nestlings.

The yolk of bird eggs contains maternal carotenoids that may act as antioxidants thus influencing offspring performance and survival. However, to our knowledge, this hypothesis has not been subjected to experimental tests and the function of transmission of carotenoids to the egg is largely unknown. We directly manipulated the concentration of the main carotenoid (lutein) in the eggs of barn swallows (Hirundo rustica) and analysed the effect of experimental manipulation on growth of nestlings and two fundamental components of their acquired immunity. Nestlings hatched from lutein-inoculated eggs had larger T-cell-mediated immune response compared with those of two control groups. T-cell-mediated immune response predicted nestling survival until fledging. However, lutein inoculation did not affect antibody response to an immunogen, body mass, tarsus length or plumage development. Nestling body mass and plumage development declined with egg laying order, but the effects of lutein inoculation were independent of egg laying order for all traits. Our results show that maternal yolk carotenoids can have a major effect in promoting a fundamental component of immunity that predicts offspring survival and suggests that adaptive early maternal effects can be mediated by transmission of antioxidants to eggs.

Animals↗
PubMed2004

Bayesian support vector regression using a unified loss function.

In this paper, we use a unified loss function, called the soft insensitive loss function, for Bayesian support vector regression. We follow standard Gaussian processes for regression to set up the Bayesian framework, in which the unified loss function is used in the likelihood evaluation. Under this framework, the maximum a posteriori estimate of the function values corresponds to the solution of an extended support vector regression problem. The overall approach has the merits of support vector regression such as convex quadratic programming and sparsity in solution representation. It also has the advantages of Bayesian methods for model adaptation and error bars of its predictions. Experimental results on simulated and real-world data sets indicate that the approach works well even on large data sets.

Bayes Theorem↗
PubMed2006

Unsupervised, information-theoretic, adaptive image filtering for image restoration.

Image restoration is an important and widely studied problem in computer vision and image processing. Various image filtering strategies have been effective, but invariably make strong assumptions about the properties of the signal and/or degradation. Hence, these methods lack the generality to be easily applied to new applications or diverse image collections. This paper describes a novel unsupervised, information-theoretic, adaptive filter (UINTA) that improves the predictability of pixel intensities from their neighborhoods by decreasing their joint entropy. In this way, UINTA automatically discovers the statistical properties of the signal and can thereby restore a wide spectrum of images. The paper describes the formulation to minimize the joint entropy measure and presents several important practical considerations in estimating neighborhood statistics. It presents a series of results on both real and synthetic data along with comparisons with current state-of-the-art techniques, including novel applications to medical image processing.

Algorithms↗
PubMed2006

Deterministic approach to robust adaptive learning of fuzzy models.

This study is concerned with the adaptive learning of an interpretable Sugeno-type fuzzy inference system, in a deterministic framework, in the presence of data uncertainties and modeling errors. The authors explore the use of Hinfinity estimation theory and least squares estimation for online learning of membership functions and consequent parameters without making any assumption and requiring a priori knowledge of upper bounds, statistics, and distribution of data uncertainties and modeling errors. The issues of data uncertainties, modeling errors, and time variations have been considered mathematically in a sensible way. The proposed robust approach to the adaptive learning of fuzzy models has been illustrated through the examples of adaptive system identification, time-series prediction, and estimation of an uncertain process.

Algorithms↗
PubMed2004

The effect of learning on experimental evolution of resource preference in Drosophila melanogaster.

Learning is thought to be adaptive in variable environments, whereas constant, predictable environments are supposed to favor unconditional, genetically fixed responses. A dichotomous view of behavior as either learned or innate ignores a potential evolutionary interaction between the learned and innate components of a behavioral response. We addressed this interaction in the context of oviposition substrate choice in Drosophila melanogaster, asking two main questions. First, will learning also evolve in a constant environment in which it always pays to show the same choice? Second, how does an opportunity to learn affect the evolution of the innate (genetic) component of oviposition substrate choice? We exposed experimental populations to four selection regimes, involving selection on oviposition substrate preference (an orange versus a pineapple medium). In two selection regimes the flies were selected for preference either for the orange medium, or for the pineapple medium. In the remaining two selection regimes the flies were also selected for preference for either orange or pineapple, but additionally could use past experience (aversion learning) to decide which medium it paid to avoid. Lines exposed to the latter selection regimes evolved improved learning ability, indicating that learning may be advantageous even if the same behavioral response is favored every generation. Furthermore, of the two selection regimes that favored oviposition on the pineapple medium, the regime that allowed for learning led to the evolution of a stronger innate preference for pineapple, than the regime that did not allow for learning. In contrast, of the two regimes that selected for oviposition on the orange medium, the one that allowed for learning led to a smaller evolutionary change of the innate preference. Thus, an opportunity to learn facilitated the evolution of innate preference under selection for preference for pineapple, but hindered it under selection for preference for orange. We discuss possible mechanisms for this effect.

Analysis of Variance↗
PubMed1988

Huntington disease carrier status and the problems involved for those affected. A psychotherapeutic experience.

The paper presents a case report of a clinically healthy woman with a family history of Huntington disease, whose child developed symptoms of the disease at the age of 8 years. Psychotherapeutic treatment for more than 18 months has provided insight into the problems associated with being an unsymptomatic carrier of the gene and helps to elucidate some aspects of predictive testing.

Adaptation, Psychological↗
PubMed1999

Socio-economic re-structuring and employment: the case of minority ethnic groups.

The consequences of major changes in employment, due to the decline of manufacturing and the growth of the service sector, have not been well-documented, nor theorized, in the sociology of ethnic relations, even in recent studies. For example, Blumer's classic argument that economic development adapts to 'race relations', rather than the reverse as predicted by the modernization school, has not been either empirically resolved or conceptually applied to the UK. By adapting data from the Labour Force Survey and the Census, the paper begins to fill this gap with a detailed account of three main minority ethnic groups, and a separate analysis of male and female employment. It is demonstrated that, contrary to assumptions that members of the minority ethnic groups suffered most from de-industrialization, they actually did rather well, and in some cases did better than the majority population. These findings are re-conceptualized as collective social mobility, as part of a review of a number of conceptual frameworks in the light of the data.

Employment↗
PubMed1998

The long-term course of autistic disorders: update on follow-up studies.

The majority of children with autism show deviance and socially or psychiatrically handicapping conditions throughout life. Only a small proportion of those with classical childhood autism lead independent adult lives. Others, particularly those with 'high-functioning' autism and so-called Asperger syndrome will improve enough to live an independent adult life. The level of mental retardation and other comorbid conditions (such as medical syndromes and other neuropsychiatric disorders, including epilepsy) is important in predicting outcome. An IQ below 50 around school age predicts severe restriction of social and adaptive functioning in adult life. The absence of communicative speech at 5-6 years of age is indicative of a poorer long-term overall outcome. There is a clear co-variation between IQ and level of communication, but probably there is some prognostic factor in language development apart from this. Measures of flexibility and cognitive shifting abilities tend to be good predictors of social outcome in a few studies. There is a continued need for prospective, longitudinal studies of children with autism spectrum disorders, particularly in Asperger syndrome. The role of interventions of various kinds needs to be addressed in such studies.

Activities of Daily Living↗
PubMed1984

Divorce, socioeconomic status, and children's cognitive-social competence at school entry.

All 115 kindergarteners in a suburban school district were evaluated with an extensive battery of intellectual, academic, social, and adaptive behavior measures to determine the predictive significance of single-parent status on school-entry competencies. Divorce was found to add significant amounts of independent variance to the socioeconomic status predictions of several criteria, specifically those relating to social and academic competence. Both single-parent status and SES were more powerful predictors than other family background, developmental history, and health variables.

Achievement↗
PubMed2025

Reproductive Isolation due to Divergent Ecological Selection Is Accompanied by Vast Genomic Instability in Experimentally Evolved Yeast Populations.

Populations evolving independently in divergent environments accumulate genetic differences and potentially evolve reproductive isolation as a by-product of divergence. The speed and mechanisms underlying this process are difficult to investigate because we rarely get the opportunity to witness them in natural settings, and histories of selection and gene flow between populations are often unknown. Here, we experimentally evolved yeast for 1000 generations of evolution in both divergent and parallel environments. At regular time points during experimental evolution, we made crosses between parallel- and divergent-evolving populations to measure postzygotic reproductive isolation (gamete viability). We used whole genome population sequencing to determine the mutational load, the number and types of structural variation, and other genomic features of the parent, F1 and F2 intraspecific hybrids. We found evidence for large-scale phenotypic and genome-wide differentiation in response to divergent laboratory selection. Divergent-selected populations produced hybrids with reduced gamete viability-a classic signature of postzygotic reproductive isolation in the form of hybrid breakdown. Parallel-selected populations, on the other hand, remained more reproductively compatible (with exceptions). We found that F2 hybrid genomes contained vast genomic instability, that is, new structural variants (especially insertions, deletions and interchromosomal translocations) that were not observed in parent and F1 genomes, which is likely a result of chromosome missegregation and recombination errors in hybrid meiosis. Our results provide phenotypic and genomic evidence that partial reproductive isolation evolved due to adaptation to divergent environments, consistent with predictions of ecological speciation theory.

Reproductive Isolation↗
PubMed1972

The effect of real and simulated time-zone shifts upon the circadian rhythms of body temperature, plasma 11-hydroxycorticosteroids, and renal excretion in human subjects.

1. Observations were made upon five subjects who flew through 4(1/2)-6 time zones, four of them returning later to their starting point, and upon twenty-three subjects experiencing simulated 6 or 8 hr time zones shifts in either direction in an isolation unit.2. Measurements were made of plasma concentration of 11-hydroxycorticosteroids, of body temperature, and of urinary excretion of sodium, potassium and chloride. Their rhythm was defined, where possible, by fitting a sine curve of period 24 hr to each separate 24-hr stretch of data and computing the acrophase, or maximum predicted by the sine curve.3. The adaptation of the plasma steroid rhythm was assessed by the presence of a sharp fall in concentration after the sample collected around 08.00 hr. The time course of adaptation varied widely between individuals; it was usually largely complete by the fourth day after westward, and rather later after eastward, flights. After time shift the pattern often corresponded neither to an adapted nor to an unadapted one, and in a subject followed for many months after a real flight a normal amplitude only appeared 2-3 months after flight.4. Temperature rhythm adapted by a movement of the acrophase, without change in amplitude, although on some days no rhythm could be observed. This movement was always substantial even on the first day, and was usually nearly complete by the fifth.5. High nocturnal excretion of electrolyte was often seen in the early days after time shift, more notably after simulated westward flights. Adaptation of urinary electrolyte rhythms usually proceeded as with temperature, but the movement of the acrophase was slower, more variable between individuals, more erratic, and sometimes reversed after partial adaptation. On a few days there were two maxima corresponding to those expected on real and on experimental time.6. Sodium excretion was much less regular than that of potassium, but adapted more rapidly to time shift, so that the two often became completely dissociated. Chloride behaved much as sodium.7. The time course of adaptation of the plasma steroid and urinary potassium rhythms were sufficiently similar to suggest a causal connexion. The time course of adaptation of the temperature rhythm did not coincide with that of any other component considered here.

Adrenal Cortex Hormones↗
PubMed2003

3-D finite-element models of human and monkey fingertips to investigate the mechanics of tactile sense.

The biomechanics of skin and underlying tissues plays a fundamental role in the human sense of touch. It governs the mechanics of contact between the skin and an object, the transmission of the mechanical signals through the skin, and their transduction into neural signals by the mechanoreceptors. To better understand the mechanics of touch, it is necessary to establish quantitative relationships between the loads imposed on the skin by an object, the state of stresses/strains at mechanoreceptor locations, and the resulting neural response. Towards this goal, 3-D finite-element models of human and monkey fingertips with realistic external geometries were developed. By computing fingertip model deformations under line loads, it was shown that a multi-layered model was necessary to match previously obtained in vivo data on skin surface displacements. An optimal ratio of elastic moduli of the layers was determined through numerical experiments whose results were matched with empirical data. Numerical values of the elastic moduli of the skin layers were obtained by matching computed results with empirically determined force-displacement relationships for a variety of indentors. Finally, as an example of the relevance of the model to the study of tactile neural response, the multilayered 3-D finite-element model was shown to be able to predict the responses of the slowly adapting type I (SA-I) mechanoreceptors to indentations by complex object shapes.

Animals↗
PubMed1995

The perception of amplified speech by listeners with hearing loss: acoustic correlates.

Audibility-based approaches to hearing-aid selection generally have focused on the long-term average speech spectrum (LTASS). Advances in amplification technology (e.g., multiband signal processing, level-dependent frequency shaping, full dynamic range compression, adaptive compression) make it difficult to predict the audibility of short-term components of speech from the amplified LTASS. This study was designed to quantify the audibility of a specific phonemes as processed by two different hearing-aid circuits (linear and full dynamic range compression), and to investigate the relation between audibility and performance on a nonsense syllable recognition task. Data were obtained from three subjects with moderate sensorineural hearing loss. Nine unvoiced consonants were presented in two vowel contexts (/i/ and /a/) in both the pre- and post-vocalic position at three intensities. While the performance on selected conditions appeared to vary by hearing-aid type, only one subject showed a statistically significant difference between the two hearing-aid systems. Acoustic analyses revealed a variety of spectral and temporal changes to the speech signal following processing. Estimates of audibility were based upon each subject's thresholds and an acoustic analysis of the amplified signal that varied across phonemes and consonant position. A signal detection approach was used to predict performance from a simple measure of audibility.

Amplifiers, Electronic↗
PubMed2000

Song replay during sleep and computational rules for sensorimotor vocal learning.

Songbirds learn a correspondence between vocal-motor output and auditory feedback during development. For neurons in a motor cortex analog of adult zebra finches, we show that the timing and structure of activity elicited by the playback of song during sleep matches activity during daytime singing. The motor activity leads syllables, and the matching sensory response depends on a sequence of typically up to three of the preceding syllables. Thus, sensorimotor correspondence is reflected in temporally precise activity patterns of single neurons that use long sensory memories to predict syllable sequences. Additionally, "spontaneous" activity of these neurons during sleep matches their sensorimotor activity, a form of song "replay." These data suggest a model whereby sensorimotor correspondences are stored during singing but do not modify behavior, and off-line comparison (e.g., during sleep) of rehearsed motor output and predicted sensory feedback is used to adaptively shape motor output.

Acoustic Stimulation↗