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PubMed1995

Receptor encoding of moving tactile stimuli in humans. II. The mean response of individual low-threshold mechanoreceptors to motion across the receptive field.

The mean firing rate evoked in 70 cutaneous, low-threshold mechanoreceptors in the human median, radial, and inferior alveolar nerves by stimulus motion across the skin was quantitatively studied. Moving stimuli, controlled for velocity, direction, and length of skin traversed, were provided by a servo-controlled motor that carried a brush across the receptive field. Each unit was studied with stimuli delivered at multiple velocities from 0.5 to 32 cm/sec in at least two opposing directions. A power function provided an excellent description of the MFR-versus-velocity relationship. The exponent n was interpreted to reflect the receptor's sensitivity to changes in stimulus velocity, and the multiplicative constant c, the predicted response to stimuli moving at 1.0 cm/sec. The fast adapting mechanoreceptors exhibited higher sensitivity to stimulus velocity than the slowly adapting mechanoreceptors. The mean velocity at which the fast adapting units were predicted to first respond to movement was also higher. Estimates of n, c, or both differed significantly for stimuli delivered in opposing directions for more than 70% of the mechanoreceptors. No direction of motion consistently led to power function parameters with higher values so as to suggest a "preferred" regional direction of motion for the entire population. Neither the directional difference in n nor c could be attributed to directional differences in the forces applied across the receptive fields. These findings suggest that information about velocity and direction is represented in the mean firing rate responses evoked in the population of mechanoreceptors activated by a moving tactile stimulus.

Adult↗
PubMed1991

Adaptability of restrained molecular dynamics for tertiary structure prediction: application to Crotalus atrox venom phospholipase A2.

In order to assess the adaptability and/or applicability of the restrained molecular dynamics (RMD) simulation for building a possible tertiary structure of a protein from the X-ray crystal structure of a family reference protein, the tertiary structure prediction of Crotalus atrox venom phospholipase A2 (PLA2) was attempted based on the X-ray crystal structure of bovine pancreatic PLA2. For the formation of secondary and tertiary structures from the fully extended starting structure, the RMD simulation with interatomic distance restraints and torsion angle restraints, which were derived from homologous amino acid sequence regions in the reference protein, was carried out until the molecular system was fully equilibrated. The predicted tertiary structure of C. atrox venom PLA2 was compared with its X-ray crystal structure, and furthermore the utility of this method was discussed by reference to the similar tertiary structure prediction of beta-trypsin from the X-ray crystal structure of an elastase.

Amino Acid Sequence↗
PubMed2004

Predicting stress fractures using a probabilistic model of damage, repair and adaptation.

This paper is concerned with the theoretical prediction of stress fractures in the bones of athletes, soldiers and others during periods of intensive exercise. Previously [J. Orthop. Res. 19 (2001) 919] we showed that test data on the fatigue strength of bone in vitro could be described using Weibull's probabilistic model, allowing predictions to be made of the probability of failure as a function of time under cyclic loading. This paper extends the earlier argument by including two living processes which act to reduce the incidence of failure: (i) repair of damage, and; (ii) adaptation by bone deposition. Having incorporated these aspects into the mathematical model, we applied the theory to a specific case: the human second metatarsal. We predicted a 17% incidence of stress fractures, all occurring within 6 weeks of commencement of the training programme. These predictions agreed well with clinical findings. Interestingly, we concluded that the major effect in preventing stress fractures comes from repair rather than from adaptation, which has a relatively minor role because it acts more slowly.

Adaptation, Physiological↗
PubMed2004

[Observational study of criteria involved in the choice of hormone replacement therapy (HRT), when initiated and subsequently adapted].

OBJECTIVES: Multicentre observational longitudinal prospective study in France; search for criteria involved in the choice of the initial dose of oestrogen at the initiation of hormone replacement therapy (HRT); search for explicative and predictive factors for treatment adaptation. PATIENTS AND METHODS STATISTICS: description and analysis (factorial analysis of multiple correspondences) of the criteria involved in the choice of the initial dose of oestrogen; percentage of women with treatment adaptation ; analysis (univariate, multivariate) of predictive factors for adaptation. RESULTS: Six hundred and fifty postmenopausal women, first treated with HRT, with complete data on modification (or not) of their treatment were included. Initial estrogen dose was dose 1 (or low dose) in 66% of patients, dose 2 (or standard dose) in 34 % of patients (N = 643). The preponderant type of HRT use was discontinuous sequential therapy and transdermal formulation. Criteria involved in the choice of the low initial dose (dose 1) were moderate hot flushes, complaint about weight gain, choice of the patient, breast tolerability, uterine bleeding, general safety, hepatic first pass. Criteria involved in the choice of the standard initial dose (dose 2) were important hot flushes, and prevention of postmenopausal osteoporosis. Treatment was adapted in 369 patients e.g. 56.8% of the population (95% CI: 53-60.6 %). The main changes (N = 291) were in 37.5% of the cases (N = 109) a decrease in the dose of estrogen (16.7% of the women (N = 37) initially under dose 2 - or standard dose) or an increase in the dose of oestrogen (17.1% of the women (N = 72) initially under dose 1 - or low dose). In 25% of the cases, there was a change in the dose or type of progestogen, in favor of norpregnane or pregnane derivates. DISCUSSION AND CONCLUSION: The following factors were associated with a decreased probability of treatment adaptation: more than 5 hot flushes at enrolment, initial dose chosen taking into account tolerance factors, history of hysterectomia, and known diabetes. Conversely, the existence of antihypertensive treatment was associated with an increased probability of treatment adaptation.

Dose-Response Relationship, Drug↗
PubMed2000

Linking childhood personality with adaptation: evidence for continuity and change across time into late adolescence.

Four personality traits--Mastery Motivation, Academic Conscientiousness, Surgent Engagement, and Agreeableness--were measured in a community sample of 205 children (ages 8-12), who were followed up 10 years later. Childhood personality was examined in relation to concurrent and longitudinal adaptation in 3 domains--academic achievement, rule-abiding versus antisocial conduct, and peer social competence. The childhood personality traits evidenced robust, conceptually coherent relationships with adaptation, both concurrently and across time. Childhood personality added to the prediction of later adaptation, beyond childhood IQ and earlier adaptation in the same domain. Few sex differences were obtained in the relationships between childhood personality and adaptation. The present results document both continuity and discontinuity in the links between childhood personality and adaptation across childhood into late adolescence.

Adolescent↗
PubMed2006

An evolutionary perspective on caching by corvids.

A principal finding in the food-caching literature is that species differences in hoarding propensity are positively correlated with species differences in degree of adaptations to caching behaviour, such as performance on spatial memory tasks and hippocampal volume. However, there are examples that do not fit this pattern. We argue that these examples can be better understood by considering the phylogenetic relatedness between species. We reconstruct the ancestral state for caching behaviour in corvids and assess when transitions in caching behaviour occurred within the corvid phylogeny. Our analysis shows that the common ancestor of all corvids was a moderate cacher. This result suggests that corvids followed a bi-directional evolutionary trajectory in which caching was secondarily lost twice and there were at least two independent transitions from moderate to specialized caching. The independent evolution of specialized cachers in the two groups must, therefore, be a case of convergent evolution. This is exemplified by the fact that specialized cachers show structurally different adaptations serving the same function to intense caching, such as different pouches to transport food. Finally, we argue that convergent evolution may have led to adaptations in memory and hippocampus that serve the same function but differ in design, and that these different adaptations may explain the examples that do not fit the pattern predicted by the adaptive specialization hypothesis.

Animals↗
PubMed1979

Continuity of individual adaptation from infancy to kindergarten: a predictive study of ego-resiliency and curiosity in preschoolers.

In this longitudinal study, individual differences in security of attachment at 18 months and effective autonomous functioning at age 2 years were related to the dimensions of ego-control and ego-resiliency at age 4--5 years. The kindergarten or nursery school teachers of 26 children completed California Child Q-Sorts. The children were also given a short form of the Block's laboratory battery (Banta's curiosity box, level of aspiration, motor impulse control delay of gratification, the Shure and Spivack Preschool Interpersonal Problem-solving Test, and the Lowenfeld mosaics). Following the Blocks, composited ego-resiliency and ego-control scores were derived from each data set. Children earlier classified as securely attached were, as predicted, significantly higher on ego-resiliency on both laboratory and Q-sort composites. They were also higher than anxiously attached infants on 3 independent measures of curiosity. An independently composited index of competence from 2-year tool-using measures also correlated significantly with later resiliency, as did 2-year measures of mothers' support and quality of assistance. The data provide initial links between the infant's quality of attachment, the toddler's effectiveness in a problem-solving situation, and competence during the preschool years.

Adaptation, Psychological↗
PubMed1993

The human/animal bond as a correlate of family functioning.

This study investigated whether selected family characteristics are predictive of family functioning. The intent was to examine whether family cohesion and adaptability could be predicted from the characteristics of family education, income, marital status, and level of pet attachment. A survey research design was used to distribute questionnaires to families in therapy in six southeastern states. Findings indicated that 15% of the variance in family adaptability could be significantly (p < .05) accounted for by the combination of family education, income, marital status, and pet attachment. However, variance in family cohesion could not be significantly accounted for by this combination of variables. Family pet attachment was significantly (p < .05) correlated with both family adaptability and family cohesion. Clinical practice implications of these findings for nurses and other health care professionals are discussed, and recommendations for future studies are identified.

Adaptation, Psychological↗
PubMed2006

Accurate prediction of enzyme subfamily class using an adaptive fuzzy k-nearest neighbor method.

Amphiphilic pseudo-amino acid composition (Am-Pse-AAC) with extra sequence-order information is a useful feature for representing enzymes. This study first utilizes the k-nearest neighbor (k-NN) rule to analyze the distribution of enzymes in the Am-Pse-AAC feature space. This analysis indicates the distributions of multiple classes of enzymes are highly overlapped. To cope with the overlap problem, this study proposes an efficient non-parametric classifier for predicting enzyme subfamily class using an adaptive fuzzy r-nearest neighbor (AFK-NN) method, where k and a fuzzy strength parameter m are adaptively specified. The fuzzy membership values of a query sample Q are dynamically determined according to the position of Q and its weighted distances to the k nearest neighbors. Using the same enzymes of the oxidoreductases family for comparisons, the prediction accuracy of AFK-NN is 76.6%, which is better than those of Support Vector Machine (73.6%), the decision tree method C5.0 (75.4%) and the existing covariant-discriminate algorithm (70.6%) using a jackknife test. To evaluate the generalization ability of AFK-NN, the datasets for all six families of entirely sequenced enzymes are established from the newly updated SWISS-PROT and ENZYME database. The accuracy of AFK-NN on the new large-scale dataset of oxidoreductases family is 83.3%, and the mean accuracy of the six families is 92.1%.

Algorithms↗
PubMed1998

Social information-processing patterns as predictors of social adaptation and behavior problems among maltreated children in foster care.

OBJECTIVE: The goal of this investigation was to determine if social information-processing patterns were predictive of later social adaptation and behavior problems within a group of maltreated children in foster care. METHOD: A longitudinal design was used to address the study hypotheses. The sample consisted of 124 maltreated children ages 5 to 10 who had been placed into foster care. Twelve months following entrance into foster care, children were presented with age-relevant hypothetical vignettes to assess the quality of the way in which they process social information. Six to 8 months following this assessment, caregivers completed the Vineland Adaptive Scales and the Child Behavior Checklist. RESULTS: Measures reflecting unbiased and competent processing were predictive of social adaptation, whereas measures reflecting biased and incompetent processing were predictive of behavior problems. In aggregate, processing measures accounted for a significant proportion of the variance in the outcome measures. CONCLUSIONS: The findings suggest that the manner in which maltreated children process social information has a bearing on their later social adaptation and behavioral adjustment. Therefore, maltreated children in foster care may benefit from interventions that target the manner in which they process social information.

Child↗
PubMed2004

Attention enhances adaptability: evidence from motion adaptation experiments.

Several previous psychophysical and neurophysiological studies have investigated the separate effects of attention and adaptation on visual processing. Here, we investigated the combined effects of attention and adaptation on motion processing by measuring the effects of spatial attention on the duration of the motion after-effect (MAE) over a wide range of stimulus contrasts. MAE duration was compared between two conditions: full-attention, subjects were required to pay attention to the adapting motion stimulus, and poor-attention, subjects performed a difficult vowel detection task at the center of gaze and ignored the adapting motion stimulus. Attention was found to increase the MAE duration by a factor of 1.4, which was approximately constant over a wide range of stimulus contrasts (3.22-80.6%). Notably, this included contrasts for which the MAE duration had reached its asymptotic value. We show that a quantitative model based on known properties of directionally selective MT neurons can explain these results by assuming that attention enhances the effects of adaptation, a phenomenon we refer to as "adaptation gain". Specifically, attending to an adapting motion stimulus shifts the semi-saturation point (C50) of the underlying contrast response function (CRF) of motion detectors roughly 1.4-fold more to the right than does ignoring that same stimulus. By enhancing the effects of adaptation in this fashion, attention is predicted to enhance the adaptability of the visual motion system.

Adaptation, Physiological↗
PubMed2000

Adaptability in the workplace: development of a taxonomy of adaptive performance.

The purpose of this research was to develop a taxonomy of adaptive job performance and examine the implications of this taxonomy for understanding, predicting, and training adaptive behavior in work settings. Two studies were conducted to address this issue. In Study 1, over 1,000 critical incidents from 21 different jobs were content analyzed to identify an 8-dimension taxonomy of adaptive performance. Study 2 reports the development and administration of an instrument, the Job Adaptability Inventory, that was used to empirically examine the proposed taxonomy in 24 different jobs. Exploratory factor analyses using data from 1,619 respondents supported the proposed 8-dimension taxonomy from Study 1. Subsequent confirmatory factor analyses on the remainder of the sample (n = 1,715) indicated a good fit for the 8-factor model. Results and implications are discussed.

Adaptation, Psychological↗
PubMed2005

Closing in on the C. elegans ORFeome by cloning TWINSCAN predictions.

The genome of Caenorhabditis elegans was the first animal genome to be sequenced. Although considerable effort has been devoted to annotating it, the standard WormBase annotation contains thousands of predicted genes for which there is no cDNA or EST evidence. We hypothesized that a more complete experimental annotation could be obtained by creating a more accurate gene-prediction program and then amplifying and sequencing predicted genes. Our approach was to adapt the TWINSCAN gene prediction system to C. elegans and C. briggsae and to improve its splice site and intron-length models. The resulting system has 60% sensitivity and 58% specificity in exact prediction of open reading frames (ORFs), and hence, proteins-the best results we are aware of any multicellular organism. We then attempted to amplify, clone, and sequence 265 TWINSCAN-predicted ORFs that did not overlap WormBase gene annotations. The success rate was 55%, adding 146 genes that were completely absent from WormBase to the ORF clone collection (ORFeome). The same procedure had a 7% success rate on 90 Worm Base "predicted" genes that do not overlap TWINSCAN predictions. These results indicate that the accuracy of WormBase could be significantly increased by replacing its partially curated predicted genes with TWINSCAN predictions. The technology described in this study will continue to drive the C. elegans ORFeome toward completion and contribute to the annotation of the three Caenorhabditis species currently being sequenced. The results also suggest that this technology can significantly improve our knowledge of the "parts list" for even the best-studied model organisms.

Animals↗
PubMed2002

The application of a new predictive technique for lossless compression of medical images.

A new predictive technique for lossless compression is applied to CT and MR images in order to achieve high compression in the lossless mode. To accomplish this, a prediction value was obtained by assuming the horizontal and vertical components of each pixel. Wide and narrow predictive coding modes were adaptively selected to achieve an accurate prediction. The performance of the predictive technique was compared with the performance of four representative compression techniques in the lossless mode, using different types of CT and MR image sets with different bit rates. Overall, the proposed predictive technique yielded the best compression, particularly with the lower bit-rate images tested. While the compression results are largely dependent on the images used, the results confirm the strong potential of the proposed predictive technique as a strategy for obtaining high lossless-compression in medical images.

Humans↗
PubMed1985

Conversion of the FokI endonuclease to a universal restriction enzyme: cleavage of phage M13mp7 DNA at predetermined sites.

Endonuclease FokI belongs to class IIS of restriction enzymes, for which the DNA cut points lie outside the enzyme-recognition sites. This permitted conferring new cleavage specificities by combining FokI with tailored oligodeoxynucleotide adapters. Such adapters carry a single-stranded (ss) target-recognition domain, complementary to the selected ss target DNA, and a double-stranded (ds) enzyme-recognition site. Neither enzyme nor adapter alone has endonucleolytic activity toward phage M13mp7 ss DNA, whereas the enzyme-adapter complex cleaves this ss target DNA at the particular sites foreordained by the sequence of the ss domain of the adapter. Two kinds of adapters (32 and 34 nucleotides long), with opposing orientations of the asymmetric FokI recognition site, were constructed and shown to direct specific cleavage under a variety of conditions. In addition to FokI, other class IIS enzymes, HphI, MboII and BbvI, which alone do not cleave ss DNA, are suitable for construction of tailored enzyme-adapter complexes with predictable cleavage specificities. This report provides a preliminary experimental confirmation for the proposal of Szybalski [Gene 40 (1985) 169-173] for the design of adapter-enzyme complexes with novel and predictable specificities. Theoretically, using this approach any sequence could be precisely cleaved at a predetermined point.

Base Sequence↗
PubMed1999

A circadian oscillator model based on empirical data.

A model based on the van der Pol equation has been developed to predict the pattern of adaptation of aircrew and other travellers to rapid time-zone transitions, when the exposure to light cannot be quantified. The parameters of the model include the stiffness (mu) and the intrinsic period (T0), which together define the free-running period, and the external force (F). The parameter values were estimated by using a simplex minimization technique to fit the output from the model to body temperature data from 12 individuals before, and over a 12-day period immediately after, a 10-h eastward transition between London and Sydney. Data were collected at three equally spaced points during each sleep period and at the end of four 45-min rest periods during the day. The fitting procedure enabled the parameters of the temperature rhythm to be estimated after correcting for the masking effect of sleep. The average estimates of mu (0.38 h) and T0 (24.24 h) were close to earlier estimates based on forced desynchronization experiments, and the mean free-running period, calculated from these, was 24.50 h. The mean value of the external force F (0.54) was surprisingly high, and this may reflect the strong outdoor light levels during the days in Sydney. Estimates of phase, based on the model solutions, suggested that 11 subjects adapted by a phase delay and 1 by a phase advance. However, the amplitude of the rhythms was much reduced at times when the phase was changing rapidly. Simulations using the range of the model parameters for the 12 individuals predicted that adaptation to within 1 h after a 10-h eastward transition would be achieved within between 3 and 11 days. However, since these predictions are dependent on the choice of external force, estimates may need to be more conservative in real-life situations when light exposure cannot be measured.

Adaptation, Physiological↗
PubMed2003

Biological and environmental contributions to adaptive behavior in fragile X syndrome.

Fragile X syndrome is the most common cause of inherited developmental disability. The purpose of the present study is to understand how both biological and environmental influences affect the development of adaptive behavior in children with fragile X. In-home assessments were conducted on 120 children (80 boys and 40 girls) with the fragile X full mutation and their unaffected siblings (58 boys and 62 girls). Hierarchical multiple regression analyses were utilized. Independent variables included biological or demographic variables specific to the child (age, gender, full-scale IQ, and FMRP percentage), as well as factors specific to his/her environment (household income, home environment, maternal psychopathology, and effectiveness of educational/therapeutic services). Results of these analyses showed that for both boys with fragile X and the control sibling group, adaptive behavior was predicted by IQ, age, gender, and home environment. For girls with fragile X, adaptive behavior was most strongly associated with IQ. Adaptive behavior was not significantly associated with FMRP in boys or girls with fragile X. By examining the relative influences of biological and environmental factors on adaptive behavior in children with fragile X, we begin to lay the foundation for the development of more specific treatment studies in children with this disorder.

Adaptation, Psychological↗
PubMed2005

Distributions of beneficial fitness effects in RNA.

Beneficial mutations are the driving force of evolution by natural selection. Yet, relatively little is known about the distribution of the fitness effects of beneficial mutations in populations. Recent work of Gillespie and Orr suggested some of the first generalizations for the distributions of beneficial fitness effects and, surprisingly, they depend only weakly on biological details. In particular, the theory suggests that beneficial mutations obey an exponential distribution of fitness effects, with the same exponential parameter across different regions of genotype space, provided only that few possible beneficial mutations are available to that genotype. Here we tested this hypothesis with a quasi-empirical model of RNA evolution in which fitness is based on the secondary structures of molecules and their thermodynamic stabilities. The fitnesses of randomly selected genotypes appeared to follow a Gumbel-type distribution and thus conform to a basic assumption of adaptation theory. However, the observed distributions of beneficial fitness effects conflict with specific predictions of the theory. In particular, the distributions of beneficial fitness effects appeared exponential only when the vast majority of small-effect beneficial mutations were ignored. Additionally, the distribution of beneficial fitness effects varied with the fitness of the parent genotype. We believe that correlation of the fitness values among similar genotypes is likely the cause of the departure from the predictions of recent adaptation theory. Although in conflict with the current theory, these results suggest that more complex statistical generalizations about beneficial mutations may be possible.

Evolution, Molecular↗