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PubMed2004

Dynamic subset selection based on a fitness case topology.

A large training set of fitness cases can critically slow down genetic programming, if no appropriate subset selection method is applied. Such a method allows an individual to be evaluated on a smaller subset of fitness cases. In this paper we suggest a new subset selection method that takes the problem structure into account, while being problem independent at the same time. In order to achieve this, information about the problem structure is acquired during evolutionary search by creating a topology (relationship) on the set of fitness cases. The topology is induced by individuals of the evolving population. This is done by increasing the strength of the relation between two fitness cases, if an individual of the population is able to solve both of them. Our new topology-based subset selection method chooses a subset, such that fitness cases in this subset are as distantly related as is possible with respect to the induced topology. We compare topology-based selection of fitness cases with dynamic subset selection and stochastic subset sampling on four different problems. On average, runs with topology-based selection show faster progress than the others.

Algorithms↗
PubMed2003

Zernike polynomial fitting fails to represent all visually significant corneal aberrations.

PURPOSE: It is assumed that wavefront error data arising from aberrometry are adequately described by a Zernike polynomial function, although this assumption has not been extensively tested. Inaccuracies in wavefront error may compromise clinical testing and refractive correction procedures. The current retrospective study correlates visual acuity with corneal wavefront error and with the residual surface elevation error after fitting with the Zernike method. METHODS: Corneal topography maps were obtained from 32 keratoconus cases, 27 postoperative penetrating keratoplasty cases, and 29 postoperative conductive keratoplasty cases (88 total). The best spectacle-corrected visual acuity (BSCVA) for each case ranged from -0.2 to 1.3 logarithm of the minimum angle of resolution (logMAR) units (20/12.5-20/400). Topography was analyzed to determine wavefront error and the elevation fit error for a 4-mm optical zone. The 4th and 10th expansion series were analyzed with the 0th-order (piston) and 1st order (tip and tilt) removed. Linear regression analysis was performed. The difference in root mean square (RMS) error between the 4th- and 10th-order analyses was assessed for both wavefront and elevation fit error. RESULTS: The correlation of BSCVA to wavefront error for 4th-order terms was moderately strong and significant (R2=0.581; P<0.001). The 10th-order correlation for wavefront error had a similar result (R2=0.565; P<0.001), but the regression was not significantly different from the 4th-order result. The correlation of BSCVA to the elevation fit error was strong and significant for the 4th order (R2=0.658; P<0.001). The 10th-order data had a similar result (R2=0.509; P<0.001), and there was no significant difference between the two regressions. Only 72% of the cases showed a shift toward increased wavefront error with the 10th-order series, whereas 18% lost wavefront error. All cases showed a shift toward improved elevation fit with the 10th-order expansion. CONCLUSIONS: The wavefront error correlation to acuity was moderately strong, but the corneal elevation fit error also strongly correlated with visual acuity, indicating that Zernike polynomials do not fully characterize the surface shape features that influence vision and that exist in postsurgical or pathologic eyes. In addition, the change in wavefront error when using a larger expansion series was found to increase or diminish somewhat unpredictably. The authors conclude that Zernike polynomials fail to model all the information that influences visual acuity, which may confound clinical diagnosis and treatment.

Cornea↗
PubMed2006

Becoming the Harvard man: person-environment fit, personality development, and academic success.

The continuity and change of the needs and evaluations of the college environment and person-environment fit (PE fit) with the college environment were studied in a 4-year longitudinal study of students (N = 191). Perceptions of the environment changed more dramatically than corresponding self-perceived needs. PE fit demonstrated moderate levels of consistency over the 4-year span, but no significant increases in mean levels were found over time. Antecedents to PE fit in the college environment included both intelligence and openness to experience. Outcomes associated with PE fit included changes in personality traits linked to openness to experience and higher academic achievement. The implications of the findings for personality development and the relationship of PE fit to successful outcomes are discussed.

Educational Status↗
PubMedDate not supplied

Patient-physician fit: an exploratory study of a multidimensional instrument.

BACKGROUND: Patients face difficulty selecting physicians because they have little knowledge of how physicians' behaviors fit with their own preferences. OBJECTIVE: To develop scales of patient and physician behavior preferences and determine whether patient-physician fit is associated with patient satisfaction. DESIGN: Two cross-sectional surveys of patients and providers. SETTING: Ambulatory clinics at a university medical center. Participants. Eight general internists, 14 family physicians, and 193 patients. MEASUREMENTS: Two instruments were developed to measure 6 preferences for physician behaviors: 1) considering nonmedical aspects of the patient's life, 2) familiarity with herbal medicine, 3) physician decision making, 4) providing information, 5) considering the patient's religion, and 6) treating what the patient perceives as his or her problem. Patients reported how they would prefer physicians to behave, and physicians reported how they preferred to behave. Patients also rated satisfaction with their physician. RESULTS: Post hoc tests found that as a group, patients scored higher than physicians in preference for the physician to provide information and lower in preference for considering nonmedical aspects of the patient's life and religious beliefs. As hypothesized, preference differences accounted for significant variance in satisfaction in overall tests (19% in the family medicine patients and 25% in internal medicine patients). Greater satisfaction was associated with fit between patient and physician preferences for physician decision making (in the internal medicine patients) and with fit in providing information and consideration of religion (in family medicine patients) CONCLUSIONS: Patients often prefer behaviors other than how their physicians prefer to behave. Preference fit is associated with enhanced patient satisfaction. Physicians should attend to whether patients want religion and other nonmedical aspects of their lives considered. Health plans may wish to provide tools to help patients choose physicians by fit.

Academic Medical Centers↗
PubMedDate not supplied

Fitting of protective football equipment.

As no other guide was found to illustrate and describe protective equipment and its fitting, we have prepared this treatise. Properly fitted protective equipment for football is a must to prevent injury from occurring. Many injuries result from improperly fitted equipment. The helmet and shoulder pads are the most important pieces of equipment that require proper fit. Adequate face masks and jaw pads are essential to the helmet. Cantilever shoulder pads are necessary for most positions, with straps for those with subluxating or dislocating shoulders. Other pieces of equipment that need attention are cervical collars, hip pads, thigh pads, knee pads, pants, and shoes. Elbow, forearm, wrist, hand, and mouthpieces are essential to the player and care must be taken to see that they are compatible with proper fit. Special materials such as Ensolite, Hexcelite, RTV-11, Orthoplast, Lightcast, or Therm-O-Foam may be utilized to construct special pads. Today's modern football equipment provides adequate protection. It is imperative that all personnel involved in fitting equipment be knowledgeable about the subject.

Athletic Injuries↗
PubMed1998

Fitness to stand trial: characteristics of remands since the 1992 Criminal Code amendments.

OBJECTIVE: To examine the characteristics of a sample of remands after the introduction of the 1992 Criminal Code amendments, to compare those deemed fit with those deemed unfit as the result of an institution-based evaluation of fitness, and to determine the impact of the Code changes on one's detention period by investigating the length of time that individuals were held on remand. METHOD: File information was collected and analyzed for 180 males who were remanded for inpatient evaluations of their fitness to stand trial between October 1994 and July 1995. RESULTS: The results indicated that remanded defendants are more likely to be single, unemployed, and living alone and that unfit defendants are significantly more likely to have never been married. As well, individuals who were found to be unfit to stand trial were significantly less likely to have been diagnosed with a drug- or alcohol-use disorder and were 4 times more likely to have been diagnosed with a psychotic disorder. The results also indicated that while the 1992 Criminal Code revisions called for a 5-day evaluation period, it appears that this is rarely accomplished, and, in fact, the average length of time for an assessment of fitness is 23 days. Finally, the majority of remanded individuals are certified and treated with psychotropic medications while on remand. CONCLUSION: The results of this study suggest that the fitness remand period is being used for purposes other than assessing fitness.

Adult↗
PubMed2005

Parental exercise is associated with Australian children's extracurricular sports participation and cardiorespiratory fitness: A cross-sectional study.

BACKGROUND: The relationship between parental physical activity and children's physical activity and cardiorespiratory fitness has not been well studied in the Australian context. Given the increasing focus on physical activity and childhood obesity, it is important to understand correlates of children's physical activity. This study aimed to investigate whether parental exercise was associated with children's extracurricular sports participation and cardiorespiratory fitness. METHODS: The data were drawn from a nationally representative sample (n = 8,484) of 7-15 year old Australian schoolchildren, surveyed as part of the Australian Schools Health and Fitness Survey in 1985. A subset of 5,929 children aged 9-15 years reported their participation in extracurricular sports and their parents' exercise. Cardiorespiratory fitness was measured using the 1.6 km (1-mile) run/walk and in addition for children aged 9, 12 or 15 years, using a physical work capacity test (PWC170). RESULTS: While the magnitude of the differences were small, parental exercise was positively associated with children's extracurricular sports participation (p < 0.001), 1.6 km run/walk time (p < 0.001) and, in girls only, PWC170 (p = 0.013). In most instances, when only one parent was active, the sex of that parent was not an independent predictor of the child's extracurricular sports participation and cardiorespiratory fitness. CONCLUSION: Parental exercise may influence their children's participation in extracurricular sports and their cardiorespiratory fitness levels. Understanding the correlates of children's extracurricular sport participation is important for the targeting of health promotion and public health interventions, and may influence children's future health status.

Journal Article↗
PubMed2006

International Physical Activity Questionnaire: Validity against fitness.

PURPOSE: This study was conducted to criterion-validate the short format of International Physical Activity Questionnaire (IPAQ) against health-related fitness. METHODS: Participants included 951 men, aged 21-43 yr. VO2max by ergometer was used to measure cardiorespiratory fitness. Muscular fitness tests included the number of sit-ups, push-ups, and squats performed during 60 s. Physical activity was assessed from IPAQ by categories for health (health-enhancing physical activity (HEPA)) and by calculating total and vigorous MET-hours per week. The participants were classified in five groups of almost equal size by the IPAQ outcomes. Moreover, the frequency of vigorous activity was assessed by one precoded question (single-item question on leisure-time vigorous physical activity (SIVAQ)). RESULTS: The mean fitness improved from the first through the fourth IPAQ group. VO2max in the most active IPAQ group, however, was lower than in the fourth group (P < 0.05), both with HEPA categories and vigorous METs as the outcome. In contrast, the weekly frequency of vigorous physical activity showed a positive association with fitness through all six categories. The 65 sedentary (according to SIVAQ) and unfit individuals who belonged to the highest 20% (by IPAQ total METs) were older (30.6 +/- 5.1 vs 28.9 +/- 3.8, P = 0.02), more obese (waist 93 +/- 12 vs 89 +/- 10 cm), more often current smokers (59.4 vs 42.0%; P = 0.03), and less educated (<12 yr of education 70.8 vs 52.0%; P = 0.02), compared with the others in the highest IPAQ group. CONCLUSIONS: Almost 10% of young men had poor fitness and apparently low physical activity, but they reported very high physical activity by IPAQ. An evident need therefore exists to develop IPAQ further to solve the apparent overreporting by a considerable proportion of sedentary individuals.

Adult↗
PubMed1990

Fitness and its components in Drosophila melanogaster.

Fitness and its components in Drosophila melanogaster were estimated under the homozygous condition. All of these parameters, except for egg-to-adult viability and female fecundity, were measured under interspecific competition with D. hydei. The following results were obtained: (1) Significant genetic variation was detected in fitness, productivity, adult viability, total egg-to-adult viability and female fecundity. (2) Significant correlation was obtained between fitness and productivity (rp = 0.792 for phenotypic correlation, rg = 0.945 for genotypic correlation), between fitness and total egg-to-adult viability (rp = 0.355, rg = 0.395), and between fitness and female fecundity (rp = 0.451, rg = 0.511). (3) There was no significant correlation between total egg-to-adult viability and fecundity (rp = -0.046). The biological implications of the interrelationship between fitness and its components are discussed.

Animals↗
PubMed2006

Continence: sizing and fitting a penile sheath.

Male patients suffering from urinary incontinence can benefit from being fitted with a penile sheath and drainage bag rather than using incontinence pads or having to have an indwelling catheter to treat or manage their problem. In selecting a penile sheath it is important to select the correct size of sheath to fit onto the shaft of penis and length of sheath. A penile sheath fitted too small may cause problems not only in drainage of urine but also by restricting blood circulation to the shaft of the penis. A penile sheath fitted too large will cause creases to form, allowing urine leakage and causing the sheath to fail and fall off. This article explains what is required before fitting a penile sheath, examines various sheaths and alternatives, and how to fit one correctly.

Activities of Daily Living↗
PubMed2003

Maximum-likelihood curve-fitting scheme for experiments with pulsed lasers subject to intensity fluctuations.

Evaluation schemes, e.g., least-squares fitting, are not generally applicable to any types of experiments. If the evaluation schemes were not derived from a measurement model that properly described the experiment to be evaluated, poorer precision or accuracy than attainable from the measured data could result. We outline ways in which statistical data evaluation schemes should be derived for all types of experiment, and we demonstrate them for laser-spectroscopic experiments, in which pulse-to-pulse fluctuations of the laser power cause correlated variations of laser intensity and generated signal intensity. The method of maximum likelihood is demonstrated in the derivation of an appropriate fitting scheme for this type of experiment. Statistical data evaluation contains the following steps. First, one has to provide a measurement model that considers statistical variation of all enclosed variables. Second, an evaluation scheme applicable to this particular model has to be derived or provided. Third, the scheme has to be characterized in terms of accuracy and precision. A criterion for accepting an evaluation scheme is that it have accuracy and precision as close as possible to the theoretical limit. The fitting scheme derived for experiments with pulsed lasers is compared to well-established schemes in terms of fitting power and rational functions. The precision is found to be as much as three timesbetter than for simple least-squares fitting. Our scheme also suppresses the bias on the estimated model parameters that other methods may exhibit if they are applied in an uncritical fashion. We focus on experiments in nonlinear spectroscopy, but the fitting scheme derived is applicable in many scientific disciplines.

Journal Article↗
PubMed2005

Lysis timing and bacteriophage fitness.

The effect of lysis timing on bacteriophage (phage) fitness has received little theoretical or experimental attention. Previously, the impact of lysis timing on phage fitness was studied using a theoretical model based on the marginal value theorem from the optimal foraging theory. An implicit conclusion of the model is that, for any combination of host quantity and quality, an optimal time to lyse the host would exist so that the phage fitness would be the highest. To test the prediction, an array of isogenic lambda-phages that differ only in their lysis times was constructed. For each phage strain, the lysis time, burst size, and fitness (growth rate) were determined. The result showed that there is a positive linear relationship between lysis time and burst size. Moreover, the strain with an intermediate lysis time has the highest fitness, indicating the existence of an optimal lysis time. A mathematical model is also constructed to describe the population dynamics of phage infection. Computer simulations using parameter values derived from phage lambda-infection also showed an optimal lysis time. However, both the optimum and the fitness are different from the experimental result. The evolution of phage lysis timing is discussed from the perspectives of multiple infection and life-history trait evolution.

Bacteriolysis↗
PubMed2004

Effects of gossypol on fitness costs associated with resistance to Bt cotton in pink bollworm.

Fitness costs associated with insect resistance to Bacillus thuringiensis (Bt) crops may help to delay or prevent the spread of resistance alleles, especially when refuges of non-Bt host plants are present. The potential for such delays increases as the magnitude and dominance of fitness costs increase. Here, we examined the idea that plant secondary chemicals affect expression of fitness costs associated with resistance to Bt cotton in Pectinophora gossypiella (Saunders). Specifically, we tested the hypotheses that gossypol affects the magnitude or dominance of fitness costs, by measuring performance of three independent sets of pink bollworm populations fed artificial diet with and without gossypol. Each set had an unselected susceptible population, a resistant population derived by selection from the susceptible population, and the F1 progeny of the susceptible and resistant populations. No individuals completed development on diets with gossypol in one set, suggesting that these individuals partially lost the ability to detoxify this chemical. In the other two sets, costs affecting survival did not support the hypotheses, but costs affecting pupal weight did. Adding gossypol to diet increased the magnitude and dominance of costs affecting pupal weight. In one of the two sets with survivors on diet with gossypol, costs affecting development time were less recessive when gossypol was present in diet. These results indicate that gossypol increased the magnitude and dominance of some fitness costs. Better understanding of the effects of natural plant defenses on fitness costs could improve our ability to design refuges for managing insect resistance to Bt crops.

Animals↗
PubMed2006

Cadherin-based resistance to Bacillus thuringiensis cotton in hybrid strains of pink bollworm: fitness costs and incomplete resistance.

Recessive resistance to Bacillus thuringiensis (Bt) cotton, Gossypium hirsutum L., in laboratory-selected strains of pink bollworm, Pectinophora gossypiella (Saunders), is associated with three resistance alleles (r1, r2, and r3) of a cadherin gene. Previous experiments based on measurement of fitness components in Bt-resistant and Bt-susceptible strains revealed that fitness costs and incomplete resistance are associated with resistance. Here, we used two hybrid strains of pink bollworm, each containing a mixture of susceptible and resistant individuals, and polymerase chain reaction (PCR) amplifications to test the association between cadherin genotype and fitness components for individuals sharing a common genetic background. All survivors on Bt cotton had two r alleles, confirming that recessive cadherin alleles are tightly linked with resistance to Bt cotton. On non-Bt cotton, significantly greater developmental time for rr than ss larvae indicated a recessive fitness cost, but costs did not affect survival or pupal weight. Incomplete resistance was manifested as longer developmental time, lower survival, and smaller pupal weight in rr individuals developing on Bt cotton compared with non-Bt cotton. As in previous experiments, no significant variation in performance on Bt cotton was detected among rr genotypes. However, a meta-analysis of data from seven experiments revealed that survival on Bt cotton relative to non-Bt cotton was lower in r2r3 and higher in r1r2 compared with the other rr genotypes. Assessment of fitness components associated with cadherin genotypes in hybrid strains of pink bollworm confirms that recessive resistance to Bt cotton is associated with recessive fitness costs and incomplete resistance.

Animals↗
PubMed1997

Genetic analysis of discrete reproductive traits in sheep using linear and nonlinear models: II. Goodness of fit and predictive ability.

The performance of linear and nonlinear sire and animal models in the analyses of reproductive traits (fertility, litter size, and ovulation rate) in two sheep populations (Rambouillet and Finnsheep) was compared in terms of goodness of fit and predictive ability. Linear sire (LSM) and animal (LAM) models were used with all traits. Nonlinear models were the threshold, Poisson, and negative binomial. Threshold sire (TSM) and animal (TAM) models were also used with all traits. Litter size and ovulation rate were analyzed also with Poisson and negative binomial sire (PSM and NBSM, respectively) and animal (PAM and NBAM, respectively) models. Variance components were those reported in the companion article. For PAM a new set of variance components derived from estimates found with the linear animal model also was used (PAM-L). Mean squares error (MSE) and correlations between fitted and observed values were used to assess goodness of fit. Predictive ability was assessed by partitioning the data sets for the different traits into two subsets with the restriction that all levels of fixed effects were represented in each subset. Parameters from one subset were employed to predict observations in the other, and then MSE and correlations between observed and predicted values were used as criteria for model comparison. Within estimation procedure, breed, and trait, goodness of fit of sire and animal models was similar. Linear and threshold models resulted in similar fit, and both outperformed Poisson and negative binomial models. In terms of predictive ability, linear and threshold models performed only slightly better than Poisson and negative binomial models. Goodness of fit and predictive ability generally were better when models included permanent environmental effects.

Animals↗
PubMed2006

Parametric bootstrap for testing model fitting in the proportional hazards framework: an application to the survival analysis of Bruna dels Pirineus beef calves.

Given that correct assumptions on the baseline survival function are determinant for the validity of further inferences, specific tools to test the fit of a model to real data become essential in proportional hazards models. In this sense, we have proposed a parametric bootstrap to test the fit of survival models. Monte Carlo simulations are used to generate new data sets from the estimates obtained through the assumed models, and then bootstrap intervals can be established for the survival function along the time space studied. Significant fitting deficiencies are revealed when the real survival function is not included within the bootstrap interval. We tested this procedure in a survival data set of Bruna dels Pirineus beef calves, assuming 4 parametric models (exponential, Weibull, exponential time-dependent, Weibull time-dependent) and the Cox's semiparametric model. Fitting deficiencies were not observed for the Cox's model and the exponential time-dependent model, whereas the Weibull time-dependent model suffered from moderate overestimation at different ages. Thus, the exponential time-dependent model appears to be preferable because of its correct fit for survival data of beef calves and its smaller computational and time requirements. Exponential and Weibull models were completely rejected due to the continuous over- and underestimation of the survival probability reported. Results here highlighted the flexibility of parametric models with time-dependent effects, achieving a fit comparable to nonparametric models.

Animals↗
PubMed1985

Margin fit of metal crowns and bridge retainers.

The margin fit of metal crowns and bridge retainers was examined radiographically in individuals who were registered to receive treatment at the School of Dentistry, University of Bergen. One sample consisted of 184 individuals registered in 1967-68 and another one of 232 individuals registered in 1982-83. In all, 2057 proximal surfaces could be examined. The margin fit was scored as excess, deficit, or satisfactory. In the 1967-68 single-crown sample margin excess was recorded for 66%, margin deficit for 8%, and satisfactory fit for 26%, on the average. In the 1982-83 single-crown sample margin excess was recorded for 36%, margin deficit for 5%, and satisfactory fit for 59%. In the 1967-68 sample bridge retainer margins on the average scored 60% excess, 10% deficit, and 30% satisfactory fit. In the 1982-83 bridge retainer sample margin excess amounted to 33%, margin deficit to 4%, and satisfactory fit to 63%. The possible reasons for the differences between the two samples are discussed.

Aged↗
PubMed1992

Fitting multichannel-compression hearing aids.

Multichannel hearing aids have been introduced recently in clinical practice. In this paper, some advantages and disadvantages of multichannel hearing aids are discussed. The advantages include an improved use of compression. However, the number of settings will be larger in multichannel hearing aids and exact knowledge of the goal to be pursued by compression is more necessary than ever. Inexactness of the definitions of these goals may have been a reason for the contradictory results in the studies on multichannel compression. A number of requirements must be fulfilled for a successful application of multichannel compression. One of these is detailed knowledge about the perception of suprathreshold signals. For that reason, an extension of the battery of tests commonly used in rehabilitative audiology is necessary. Another requirement is that the fitting strategy is determined by the purpose of applying compression. The objectives will be different for compression limiting and syllabic compression. A fitting procedure used in clinical practice has to take into account some limitations in the fitting time available. A number of possible fitting tools are discussed. Two strongly different fitting strategies for the same commercially available three-channel compression aid illustrate fundamental differences in fitting philosophy.

Audiometry, Pure-Tone↗