Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Fitting”

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 1,207 records · Page 67Linked to original sources
PubMed1990

The influence of copper surface area on menstrual blood loss and iron status in women fitted with an IUD.

The influence of copper surface area on menstrual blood loss (MBL) was evaluated in 34 healthy women (mean age 36.4 +/- 1.4 yr, range 27-46 yr), who were fitted with a Multiload intrauterine device (IUD) with either 250 mm2 (MLCu-250) or 375 mm2 (MLCu-375) copper wire. MBL prior to IUD insertion was 54.4 +/- 10.3 ml for women subsequently fitted with a MLCu-250 and 56.9 +/- 6.9 ml for women fitted with a MLCu-375. An increase (p less than 0.01) in MBL was recorded 3 months after IUD insertion for both the women fitted with a MLCu-250 (86.4 +/- 10.3 ml) and a MLCu-375 (81.1 +/- 8.3 ml). This increase in MBL remained unchanged throughout the study period of one year. At no point were there any significant differences in MBL or increase in MBL between women fitted with a MLCu-250 or MLCu-375. There were no significant differences in serum ferritin, blood hemoglobin, hematocrit or erythrocyte indices before IUD insertion in the women grouped according to type of IUD, nor were any significant changes recorded in any of these parameters after IUD insertion. Thus, our findings that the increase in copper surface area from 250 mm2 to 375 mm2 had no effect on MBL were also substantiated by the hematological findings.

Adult↗
PubMed1993

The spatial location of EEG electrodes: locating the best-fitting sphere relative to cortical anatomy.

The location of the international 10-20 system electrode positions and 14 fiducial landmarks are described in cartesian coordinates (+/- 1.4 mm average accuracy). Six replications were obtained on 3 separate days from 4 normal subjects, who were compared to each other with a best-fit sphere algorithm. Test-retest reliability depended on the electrode position: the parasagittal electrodes were associated with greater measurement errors (maximum 7 mm) than midline locations. Location variability due to head shape was greatest in the temporal region, averaging 5 mm from the mean. For each subject's electrode locations a best-fitting sphere was determined (79-87 mm radius, 6% average error). A surface-fitting algorithm was used to transfer the electrode locations and best-fitting sphere to MR images of the brain and scalp. The center of the best-fitting sphere coincided with the floor of the third ventricle 5 mm anterior to the posterior commissure. The melding of EEG electrode location information with brain anatomy provides an empirical basis for associating hypothetical equivalent dipole locations with their anatomical substrates.

Adult↗
PubMed1992

Marginal fit of castable ceramic crowns.

The objective of this study was to measure marginal fit of castable ceramic versus gold crowns. Full veneer gold and ceramic crowns were made on Ivorine dies. Crowns were cemented, embedded, sectioned faciolingually and mesiodistally, and photographed for measurement of absolute marginal discrepancies (cavosurface angle to casting margin) to evaluate fit. Results revealed no statistically significant differences in fit among four locations around the margins of either ceramic or gold crowns. There was no statistically significant difference in the combined absolute marginal discrepancy (fit) between ceramic and gold crowns. The variance of the combined absolute marginal discrepancy (fit) of the ceramic crowns was significantly different than that of the gold crowns (p = 0.01 level). The standard deviation (variability) of the gold crowns was more than twice that of the ceramic crowns. Randomized block ANOVA demonstrated statistically significant differences among individual gold crown specimens, but none among individual ceramic crown specimens.

Analysis of Variance↗
PubMed1992

Fitting cancer mortality data with cumulative damage models.

Cumulative damage models conceive the epidemiologically observed aspects of carcinogenesis as some kind of total balance over a complex biological process and suggest that this total balance might behave as a wear-and-tear process. The essential concepts of this mechanistic model are exposure to a carcinogenically damaging environment and resistance of a host system against those damages. Intensity of exposure and magnitude of host resistance are the parameters to be assessed. The paper describes (1) the statistical methods for fitting this model to birth cohort data; (2) for which cancer sites the model provides acceptable fits and for which it does not; and (3) how model extensions provide improvements in the goodness of fit. It is shown that from a theoretical viewpoint the consideration of extra-Poisson variation is needed for descriptive epidemiological applications. The practical examples indicate that the present version of the model provides acceptable fits for only a few cancer sites and that refinements are needed in the majority of sites. However, plausible model extensions suggest considerable improvements of goodness of fit.

Carcinogens↗
PubMed1990

Relations among early adolescent temperament, parent and peer demands, and adjustment: a test of the goodness of fit model.

This study assessed whether the goodness of fit--between early adolescents temperaments and their parents and peers demands, or "ethnotheories", regarding temperament--was more related to adjustment than were acontextual measures of temperament alone. Data from the Pennsylvania Early Adolescent Transitions Study, a short-term longitudinal investigation of 153 adolescents from the beginning of sixth grade to the end of seventh grade, were used. Temperament was indexed by the nine attributes measured by the Revised Dimension of Temperament Survey, and the measures of demands regarding temperament were derived from different versions of this instrument. Adjustment was indexed by teacher ratings of academic and social competence and by parent ratings of problem behaviors. At the end of Grade 6 and the beginning of Grade 7, the number of significant relations between the adjustment measures and the fit scores tended to be greater than the number of significant relations between adjustment and temperament, measured alone. Moreover, groups formed on the basis of high vs. low temperament fit showed differential adjustment scores: adolescents in the low fit group in regard to both peer- and parent-demands received lower teacher ratings of scholastic competence, and higher parent ratings for conduct and school problems, than did the adolescents in the high fit group.

Child↗
PubMed1996

Influence of marginal configuration and porcelain addition on the fit of In-Ceram crowns.

The fit of In-Ceram copings and crowns was investigated in a laboratory study. Two methods were used, one a direct sectioning technique and the other a cement analogue technique using addition-cured polyvinylsiloxane impression material. The former method involved 40 crowns cemented and sectioned on their respective electroformed silver dies. For the second method, 80 analogues were embedded and sectioned. All measurements were made using a Reflex microscope. This showed In-Ceram crowns and copings to fit well with marginal openings and ranging from 1 to 63 microns and a mean of 19 microns. No significant difference in fit was found between chamfer margins and shoulder margins. The addition of porcelain to the In-Ceram coping and repeated firing cycles involved in building a crown did not alter the fit. It is concluded that In-Ceram crowns fit well in comparison to other crown types.

Analysis of Variance↗
PubMed1983

Analysis of dose-response curves and calculation of agonist dissociation constants using a weighted nonlinear curve fitting program.

The KA value of a full agonist (Furchgott, 1966) is usually calculated following the transformation of a rectangular hyperbolic relationship between equiactive concentrations into a linear relationship via a double reciprocal plot. Such a transformation will introduce error into the value of KA unless the pre- and postinactivation dose-response curves are also rectangular hyperbolas. Nonlinear curve fitting computer programs, which have been developed to evaluate radioligand binding data, fit data to rectangular hyperbolas and, thus, can be used to fit concentration-response data for pre- and postinactivation curves. Examination of (-)-isoprenaline concentration-response curves for positive inotropic effects in left atrial preparations from the guinea pig, established before and after treatment with the irreversible antagonist Ro 03-7894, indicated a marked deviation from the theoretical rectangular hyperbola (Hill coefficient greater than 1). This was accounted for by the presence of a threshold effect. The present study reports on the use of the computer program LIGAND to fit a rectangular hyperbola to the pre- and postinactivation curves for an agonist, while simultaneously calculating and allowing for the presence of a threshold phenomenon. Since both curves are fitted to rectangular hyperbolas, the KA values can be calculated with greater precision than that possible from double reciprocal plots constructed from uncorrected concentration-response curves.

Adrenergic Agonists↗
PubMed1986

A probabilistic model for fitting MWC polynomials in protein-ligand binding.

Given a binding polynomial in Adair form, A(x) = 1 + beta 1 x + ... + beta n x n, beta i greater than or equal to 0, a basic problem is to determine a method of fitting a model polynomial to A(x) and a quantitative measure of the goodness of fit. This paper presents such a method for fitting Monod-Wyman-Changeux (MWC) model polynomials when A(x) is of degree three or four. The method of fitting is based on the property that the zeros of an MWC polynomial of any degree lie on a circle in the complex plane. The parameters in the MWC model are determined so that if possible this circle coincides with the circle on which lie the zeros of A(x). The measure of goodness of fit is provided by a probabilistic model which gives the probability that a binding polynomial has its zeros on a circle on which lie the zeros of an MWC polynomial and if so, the probability that the juxtaposition of the two sets of zeros can occur by chance alone.

Kinetics↗
PubMed1994

The Harris-Galante porous acetabular component press-fit without screw fixation. Five-year radiographic analysis of primary cases.

One hundred twenty-two primary total hip arthroplasties were followed for an average of 56 months (range, 48-66 months) in which the Harris-Galante (Zimmer, Warsaw, IN) porous ingrowth acetabular component had been press-fit into the innominate bone without screw fixation. There were no acetabular fractures. No socket was revised for loosening and none were radiographically loose. There was no evidence of disruption of the titanium porous mesh. There was no acetabular osteolysis. Compared to the authors' series of primary hip reconstructions using this same prosthesis inserted with line-to-line reaming and screw fixation, the data indicate that the tight peripheral fit associated with the press-fit technique is effective in reducing both the incidence and extent of bone-implant radiolucencies. However, the increased incidence of radiolucencies near the apex of the acetabulum also suggest that initial contact of the porous surface with live acetabular bone at this location is desirable in order to obtain and maintain an optimal bone-implant interface. Additional studies are necessary to further establish the relationship between the initial fit and long-term fixation of cementless acetabular components. Based on the data and other considerations for eliminating both vascular risk and the potential for fretting wear between the screws and shell, the authors recommend press-fitting without screw fixation for this acetabular component in primary cases when anatomy and bone stock permit. Full seating of the component is recommended in order to obtain dome contact.

Acetabulum↗
PubMed2005

Assessment of distributions for fitting lag times of individual cells in bacterial populations.

To develop mathematical models describing lag times of individual bacterial cells (tau), experimental tau data were fitted to a variety of continuous distributions using BestFit. Six strains of Escherichia coli O157:H7 were used, and serial dilutions were made in Bioscreen multi-well plates to get single cells per well. Detection times (td) for individual wells were converted to tau using the maximum specific growth rate (mu) for each strain. All strains were subject to 25 trials, with up to 100 replicate wells per trial. Some strains had significantly longer t(d), and lower mu, but the tau values were not significantly different. Distributions were best fit in the order Pearson V>Pearson VI>Extreme Value>Lognormal>Lognormal2>Inverse Gaussian based on the Anderson-Darling statistic. The Lognormal distribution was selected because there was less variability in the parameter values, and parameters have specific biological meanings. Distributions could be fit to sample populations as low as six, with fittings and parameter values comparable to those obtained with larger samples (up to 89). Extreme Value, Pearson V, and Pearson VI distributions were more suitable for fitting tau values generated from a Lognormal distribution when the numbers of sample points were few, which suggested that there are similarities between the distributions. The results suggest that a Lognormal distribution can be used successfully to characterize tau.

Colony Count, Microbial↗
PubMed2004

Fitness increase of memory genomes in a viral quasispecies.

Viral quasispecies may contain a subset of minority genomes that reflect those genomic sequences that were dominant at an early phase of quasispecies evolution. Such minority genomes are referred to as memory in viral quasispecies. A memory marker previously characterized in foot-and-mouth disease virus (FMDV) is an internal oligoadenylate tract of variable length that became dominant upon serial plaque-to-plaque transfers of FMDV clones. During large population passages, genomes with internal oligoadenylate were outcompeted by wild-type revertants but remained in the mutant spectra as memory genomes. Here, we report a quantification of relative fitness of several FMDV clones, harboring internal oligoadenylate tracts of different length, and that were retrieved at early or late times (passage number) after implementation of memory. The results show that for any given length range of the oligoadenylate, maintenance in memory resulted in an increase in relative fitness, comparable to the increase undergone by the entire population. The fitness increase is in agreement with the Red Queen hypothesis, and implies a replicative memory mechanism. Thus, permanence of memory genomes may be a source of high fitness variants despite their initial low fitness, and despite having remained hidden in mutant spectra. This reinforces the interest of diagnosing minority genomes during chronic human and animal viral infections.

Animals↗
PubMed2006

An integrative transcranial magnetic stimulation mapping technique using non-linear curve fitting.

The aim of this study is to develop a new simple method for analyzing one-dimensional transcranial magnetic stimulation (TMS) mapping studies in humans. Motor evoked potentials (MEP) were recorded from the abductor pollicis brevis (APB) muscle during stimulation at nine different positions on the scalp along a line passing through the APB hot spot and the vertex. Non-linear curve fitting according to the Levenberg-Marquardt algorithm was performed on the averaged amplitude values obtained at all points to find the best-fitting symmetrical and asymmetrical peak functions. Several peak functions could be fitted to the experimental data. Across all subjects, a symmetric, bell-shaped curve, the complementary error function (erfc) gave the best results. This function is characterized by three parameters giving its amplitude, position, and width. None of the mathematical functions tested with less or more than three parameters fitted better. The amplitude and position parameters of the erfc were highly correlated with the amplitude at the hot spot and with the location of the center of gravity of the TMS curve. In conclusion, non-linear curve fitting is an accurate method for the mathematical characterization of one-dimensional TMS curves. This is the first method that provides information on amplitude, position and width simultaneously.

Adult↗
PubMed2005

Optimization of inclusive fitness.

The first fully explicit argument is given that broadly supports a widespread belief among whole-organism biologists that natural selection tends to lead to organisms acting as if maximizing their inclusive fitness. The use of optimization programs permits a clear statement of what this belief should be understood to mean, in contradistinction to the common mathematical presumption that it should be formalized as some kind of Lyapunov or even potential function. The argument reveals new details and uncovers latent assumptions. A very general genetic architecture is allowed, and there is arbitrary uncertainty. However, frequency dependence of fitnesses is not permitted. The logic of inclusive fitness immediately draws together various kinds of intra-genomic conflict, and the concept of 'p-family' is introduced. Inclusive fitness is thus incorporated into the formal Darwinism project, which aims to link the mathematics of motion (difference and differential equations) used to describe gene frequency trajectories with the mathematics of optimization used to describe purpose and design. Important questions remain to be answered in the fundamental theory of inclusive fitness.

Adaptation, Biological↗
PubMed2005

Histomorphology and microradiography of quadriceps tendon-patellar bone grafts in press-fit anterior cruciate ligament reconstruction.

The press-fit fixation technique has become an alternative fixation method in anterior cruciate ligament (ACL) reconstruction. While the stability of press-fit fixated grafts reported in the literature predominantly had been analysed by biomechanical testing, this study investigated the specific histomorphologic and microradiographic features important for graft stability, using human quadriceps tendon-patellar bone (QTPB) grafts. Six QTPB grafts with cylindrical bone plugs were obtained from frozen fresh human cadaver knees and fixed to porcine, bovine, or human femora in a press-fit technique. The specimens were plastinated, dissected into 1.5 mm slices, studied microradiographically and stained for histologic evaluation. The specimens showed an osseous inclusion of the graft within the femoral tunnel, which was most evident on the cancellous side. Histologic analysis revealed a trabecular interdigitation with a penetration of patellar and femoral trabecular structures, contributing to primary stability of the press-fit fixation. Graft inclusion was most obvious in bovine and least in human femora, assumably because of varying bone quality. The circular bone-to-bone contact in press-fit fixation technique should contribute to both rapid and stable graft healing.

Animals↗
PubMed2004

In vitro comparative analysis of the fit of gold alloy or commercially pure titanium implant-supported prostheses before and after electroerosion.

STATEMENT OF PROBLEM: For implant-supported prostheses, passive fit is critical for the success of rehabilitation, especially when alternative materials are used. PURPOSE: The purpose of this study was to compare interfacial fit of implant-supported prostheses cast in titanium to those cast in gold alloy. MATERIAL AND METHODS: Five 3-unit fixed partial dentures were fabricated in gold alloy (Degudent U) as 1-piece castings, and 5 others were similarly cast in commercially pure titanium (Grade 1). The interfacial gaps between the prostheses and the abutments were evaluated with an optical microscope, before and after electroerosion. Readings were made with both screws tightened (10 N.cm torque), and with only 1 side tightened, so as to also evaluate the passive fit of the prostheses. Data were compared statistically by 2-way analysis of variance and the post hoc Tukey multiple range test (alpha=.05). RESULTS: Before electroerosion, the interfacial gaps for the 1-piece prostheses were significantly smaller (P<.001) in the gold alloy group when the screws were tightened (Au=12.6 +/- 3.0 microm, compared to Ti=30.1 +/- 6.4 microm). When the side opposite the tightened side was analyzed, there was no significant difference between the gold alloy and titanium groups (Au=69.2 +/- 24.9 microm and Ti=94.2 +/- 39.6 microm). The electroerosion procedure significantly (P<.001) reduced the gaps at the interfaces for both groups under all conditions. Comparison between groups after electroerosion did not present significant differences when the side opposite the tightened side was analyzed, but the gold alloy group showed better fit when the tightened side was analyzed (12.8 +/- 1.4 microm for gold alloy; 29.6 +/- 4.4 microm for titanium) and when both screws were tightened (5.4 +/- 2.3 microm for gold alloy; 16.1 +/- 5.5 microm for titanium). CONCLUSIONS: Cast titanium prostheses, despite showing larger interfacial gaps between the prosthesis and abutment than those obtained with gold alloy, had improved fit after being subjected to electroerosion.

Analysis of Variance↗
PubMed2006

A clinical investigation of the fit of removable partial dental prosthesis clasp assemblies.

STATEMENT OF PROBLEM: Removable partial denture frameworks are complex castings fabricated from high-shrinkage alloys. This may result in difficulty in achieving accurate fit. PURPOSE: The purpose of this study was to evaluate which component(s) of the clasp assembly contact the abutment tooth clinically. MATERIAL AND METHODS: New and existing frameworks with at least 1 conventional prepared occlusal rest were evaluated for fit. The spacing between the bottom of each of the rests of the 50 clasp assemblies and the corresponding rest seat were recorded with vinyl polysiloxane. The fit of each rest was determined with the use of a dial caliper by measuring, in micrometers, the thickness of the record between the rest and the bottom of the rest seat. The Kennedy classification was also recorded. A 2-sample t test was used to evaluate the difference in fit between tooth-tissue supported and tooth-supported designs (alpha=.05). RESULTS: The average space between the rest and prepared rest seat was 193 +/- 203 microm, with a range of 0 to 828 mum. Twenty tooth-tissue frameworks had an average space of 136 +/- 160 microm and 30 tooth-supported frameworks had an average space of 230 +/- 222 microm. The 2-sample t test showed no significant difference for fit between tooth-tissue supported and tooth-supported frameworks (P=.1081). Twenty-four percent of rests had contact in the prepared rest seat. CONCLUSION: The majority of rests evaluated did not contact the intended surfaces.

Dental Abutments↗
PubMed2006

Mosquito transgenesis: what is the fitness cost?

The generation of transgenic mosquitoes with a minimal fitness load is a prerequisite for the success of strategies for controlling mosquito-borne diseases using transgenic insects. It is important to assemble as much information as possible on this subject because realistic estimates of transgene fitness costs are essential for modeling and planning release strategies. Transgenic mosquitoes must have minimal fitness costs, because such costs would reduce the effectiveness of the genetic drive mechanisms that are used to introduce the transgenes into field mosquito populations. Several factors affect fitness of transgenic mosquitoes, including the potential negative effect of transgene products and insertional mutagenesis. Studies to assess fitness of transgenic mosquitoes in the field (as opposed to the laboratory) are still needed.

Animals↗
PubMed2006

Flexible fitting in 3D-EM guided by the structural variability of protein superfamilies.

A method for flexible fitting of molecular models into three-dimensional electron microscopy (3D-EM) reconstructions at a resolution range of 8-12 A is proposed. The approach uses the evolutionarily related structural variability existing among the protein domains of a given superfamily, according to structural databases such as CATH. A structural alignment of domains belonging to the superfamily, followed by a principal components analysis, is performed, and the first three principal components of the decomposition are explored. Using rigid body transformations for the secondary structure elements (SSEs) plus the cyclic coordinate descent algorithm to close the loops, stereochemically correct models are built for the structure to fit. All of the models are fitted into the 3D-EM map, and the best one is selected based on crosscorrelation measures. This work applies the method to both simulated and experimental data and shows that the flexible fitting was able to produce better results than rigid body fitting.

Amino Acid Sequence↗