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PubMed2002

Tooth shape differences analyzed by biometric and morphometric approaches: a case study on two morphologically very similar lacustrine cichlid species.

Tooth shape is generally considered to be under strong genetic control, and highly species specific. It is therefore widely used for taxonomic studies. The tooth shape-based morphological classification of the Eretmodini (a tribe of closely related cichlids endemic to Lake Tanganyika), has, however, been shown to be in conflict with recent molecular data, which suggests the occurrence of parallel evolution. A detailed biometric and morphometric analysis of tooth shape has been undertaken for two genetic lineages of the taxon Eretmodus cyanostictus. The use of both landmark-based measurements and elliptic Fourier analysis reveals differences between both lineages and supports the molecular phylogeny. These differences further endorse the interpretation of parallel evolution. In addition, we here present a powerful tool for the analysis of tooth shape.

Animals↗
PubMedDate not supplied

Tensor biometrics for changes in cranial shape.

D'Arcy Thompson's method of Cartesian transformations can be adapted to the biometric study of group differences and trends in shape. The key to this extension is the symmetric tensor, a mathematical representation of the linear deformation taking one triangle onto another. These tensors may easily be computed from data that come in the form of Cartesian coordinates of homologous landmarks, such as are customary in roentgenographic cephalometrics. This article shows how the tensors make possible the rigorous statistical analysis of populations of shapes without requiring the specification of particular shape measures in advance. Instead, the findings of a study include the extraction of particular shape measures most clearly manifesting the group difference or treatment effect under study. Only conventional multivariate statistical techniques, such as Hotelling's T2, are involved. Configurations of many landmarks can be analysed via the display of their mean difference as a biorthogonal grid pair, perusal of which leads to the selection of triangles of landmarks for more rigorous analysis. The techniques are exemplified in two cephalometric studies: the description and prediction of normal craniofacial growth, and a comparison of the craniofacial deformities associated with Apert's and Crouzon's syndromes.

Biometry↗
PubMed2006

Differences in amniotic fluid patterns and fetal biometric parameters in third trimester pregnancies with and without diabetes.

OBJECTIVE: The amniotic fluid index (AFI) has been increasingly used in the assessment of fetal well-being. We conducted the study to evaluate and compare the amniotic fluid index in third trimester normal and diabetic human pregnancy and to assess the correlation between the AFI and the fetal biometric parameters. METHODS: Real-time ultrasound was performed to evaluate the AFI (four-quadrant technique), and to measure the biparietal diameter, head circumference, abdominal circumference, and femur length in 225 normal and 120 diabetic pregnant women from 27 to 42 weeks of gestation. Each patient was studied only once. RESULTS: AFI in normal pregnancies was less than that in diabetic pregnancies throughout the gestational ages studied (27-42 weeks). In normal pregnancy, the mean AFI was 14.0 cm at 27 weeks and decreased to 11.4 cm at 42 weeks (r = 0.25, p = 0.0005), whereas in diabetic pregnancies, the values remained stable throughout the gestational ages studied. There exist significant differences in AFI, estimated fetal weight, estimated fetal weight %, abdominal circumference, abdominal circumference %, and head circumference to abdominal circumference ratio between the two groups. In both normal and diabetic pregnancies, there is a positive correlation between the AFI and the percentile of abdominal circumference (p < 0.0001), and between the AFI and the percentile of estimated fetal weight (p < 0.0001). CONCLUSION: This study provides gestational age-specific values of the AFI in normal and diabetic pregnancies. Diabetic pregnancy has greater AFI values than normal pregnancy between 27 and 42 weeks. The AFI correlates to the percentile of the estimated fetal weight and the abdominal circumference in both groups, suggesting that there may be a relationship between increased AFI and large for gestational age fetus independent of diabetes.

Adult↗
PubMed1992

Aspects on osseointegrated implants inserted in growing jaws. A biometric and radiographic study in the young pig.

The aim was to study if osseointegrated implants behave like teeth in the growing jaw. Six young pigs were used, one of them randomly selected as a control. The test pigs received four fixtures each in regions with various dento-alveolar development. The biometric and radiographic findings, after an experimental period of 165 days, showed that the osseointegrated implants do not become secondarily displaced in sagittal and transversal dimensions and, thus, do not behave like normal teeth. Consequently, the osseointegration technique is not to be recommended in the lateral regions in young children.

Alveolar Process↗
PubMed1993

Biometric analysis of the dental casts of Maasai following traditional extraction of mandibular permanent central incisors and of Kikuyu children.

Dental plaster casts of 93 Maasai and 79 Kikuyu children age 12-15 years were analysed. Four biometric measurements were taken of the maxillary and mandibular casts: intercanine distance (C-C), inter-molar distance (M-M), canine arch circumference (C-C ACirc.), and molar arch circumference (M-M ACirc.). Incisor space (IS) was also measured in the mandibular casts. The mean values of all measurements except (M-M) in the mandibular casts were significantly reduced in the Maasai who had permanent central incisors extracted compared to the non-extracted Maasai and the Kikuyu. The mean incisor space in the Maasai with extractions was 6.3 mm compared to 11.7 mm in the non-extracted Maasai group. The extent of reduction of IS, C-C, C-C ACirc. and M-M ACirc. following extractions of the incisors may depend on the mesial drift of lateral incisors, jaw growth and soft tissue influence. The position of the tongue and occlusal relationship of the molars may prevent bucco-lingual movements maintaining a constant M-M. There was no significant difference in the mandibular cast dimensions of the non-extracted Maasai and the Kikuyu. Analysis of the maxillary cast dimensions of the Maasai with extraction, non-extracted Maasai and Kikuyu showed no significant differences suggesting that the extraction of mandibular incisors has no effect on maxillary arch dimensions. The variability in growth of the dento-alveolar complex itself may explain why the dental arch dimensions are similar in the Maasai and Kikuyu despite ethnic differences. There was no significant difference between the male and female dental arch dimensions.

Adolescent↗
PubMed1989

Solar equivalent leaf area: an efficient biometrical parameter of individual leaves, trees and stands.

The solar equivalent leaf area (A(s)), a simply and easily determined biometrical parameter of leaves, trees and stands, was derived theoretically. The parameter is defined as projected leaf area weighted for the time integral of irradiance at a given location in the canopy relative to that of fully irradiated leaves at the top of the canopy. The efficiency of A(s) as a basis for estimating stand-area transpiration of a mature oak (Quercus robur L.) forest from measurements of transpiration by individual trees was compared with that of other stand and tree characteristics. Stand transpiration estimates based on A(s) were more precise and less prone to systematic error than estimates based on basal area, timber volume, projected tree crown area, projected leaf area, or leaf dry mass. Solar equivalent leaf area reflects both the amount and the physiological properties of leaves and can be used as a measure of tree size and functional capacity. It can be calculated from ordinary forest inventory data on trees and stands, adjusted according to simple phyllometric data. It appears to have wide application in ecological and forestry studies for relating the physiological characteristics of individual leaves to those of entire trees or stands.

Journal Article↗
PubMed1985

Biometric estimation of chest wall thickness of females.

Optimal use of whole-body counting data to estimate pulmonary deposition of many of the actinides is dependent upon accurate measurement of the thickness of the chest wall because of severe attenuation of low-energy x rays and photons associated with the decay of these radionuclides. An algorithm for estimation of female chest wall thicknesses, verified by real-time ultrasonic measurements, has been derived based on the correlation of measured chest wall thickness and other common biometric quantities. Use of this algorithm will reduce the error generally associated with estimation of internal actinide deposition previously resulting from assuming an average chest wall thickness for all female subjects.

Actinoid Series Elements↗
PubMed1975

The prediction of glaucoma from ocular biometric data. Part 1. An application of multiple regression analysis.

Two sets of multiple regression equations (prediction systems) were derived from the analysis of ocular biometric data obtained from glaucoma patients (16 open angle; 16 angle-closure) and 75 normal subjects. Discriminant scores were established for both sets of equations which minimised the number of false negatives. One set, the 'Glaucoma Equations' was applied to the data to segregate the glaucoma from the normal subjects. The other prediction system, the 'Classification Equations,' was then applied to the group defined as glaucomatous to discriminate between patients in the angle-closure and open angle categories. The performance of these equations, obtained by comparing the predicted and actual classifications for this sample, was such that between 9 and 12% of false positives and 0 and 3% false negatives were found on the 'Glaucoma Equations' and between 6 and 12% of false positives with no false negatives on the 'Classification Equations.'

Age Factors↗
PubMed1996

Kinetics of cellular viability in warm versus cold ischemia conditions of kidney preservation. A biometric study.

We have determined the kinetics of the cellular viability ratio (CVR), defined as the number of living cells over the total cell count, in pig kidneys using propidium iodide and fluorescein diacetate staining, as a function of time and preservation conditions. The kidneys were preserved in warm or cold ischemia in order to mimic the conditions of transplantation from non-heart-beating donors or multiple removal with optimal preservation of the graft, respectively. To determine the CVR, the cells were obtained by a fine-needle aspiration biopsy, which minimizes the damage to the graft. A biometric analysis by regression enabled the determination of the time dependence for warm ischemia (CVR(t) = 80.0 x e(-0.733-t)(+2.7/-0.36)) and for cold ischemia (CVR(t) = 80.0 x e(-0.022-t)(+1.57/-0.64)) with a confidence interval of 95%. These master curves allow us to predict, under the described conditions, the CVR after a given ischemia time. The half-life of the cells can be deduced from the time-dependent CVR(t), and is 0.64 hr (38 min) for warm ischemia and 21.4 hr for cold ischemia. Further, the CVR for a given kidney can be used to assess its condition at removal: if the CVR is below 48% at 2 hr after removal, one can conclude that the organ has suffered a period of warm ischemia.

Animals↗
PubMedDate not supplied

Workshop on cancer biometrics: identifying biomarkers and surrogates of cancer in patients: a meeting held at the Masur Auditorium, National Institutes of Health.

The current excitement about molecular targeted therapies has driven much of the recent dialog in cancer diagnosis and treatment. Particularly in the biologic therapy of cancer, identifiable antigenic T-cell targets restricted by MHC molecules and the related novel stress molecules such as MICA/B and Letal allow a degree of precision previously unknown in cancer therapy. We have previously held workshops on immunologic monitoring and angiogenesis monitoring. This workshop was designed to discuss the state of the art in identification of biomarkers and surrogates of tumor in patients with cancer, with particular emphasis on assays within the blood and tumor. We distinguish this from immunologic monitoring in the sense that it is primarily a measure of the tumor burden as opposed to the immune response to it. Recommendations for intensive investigation and targeted funding to enable such strategies were developed in seven areas: genomic analysis; detection of molecular markers in peripheral blood and lymph node by tumor capture and RT-PCR; serum, plasma, and tumor proteomics; immune polymorphisms; high content screening using flow and imaging cytometry; immunohistochemistry and tissue microarrays; and assessment of immune infiltrate and necrosis in tumors. Concrete recommendations for current application and enabling further development in cancer biometrics are summarized. This will allow a more informed, rapid, and accurate assessment of novel cancer therapies.

Alternative Splicing↗
PubMed1995

A biometrical genome search in rats reveals the multigenic basis of blood pressure variation.

A genome-wide search for multiple loci influencing salt-loaded systolic blood pressure (NaSBP) variation among 188 F2 progeny from a cross between the Brown-Norway and spontaneously hypertensive rat strains was pursued in an effort to gain insight into the polygenic basis of blood pressure regulation. The results suggest that loci within five to six genomic regions collectively explain approximately 43% of the total NaSBP variation exhibited among the 188 F2 progeny. Many of these loci are in regions that previous studies have not implicated in blood pressure regulation. Ultimately, however, this study not only sheds light on the multigenic basis of blood pressure but provides further evidence that the identification of the genetic determinants of polygenic traits in mammals is possible with modern biometrical and molecular genetic tools in controlled settings (i.e., breeding paradigm and model organism).

Animals↗
PubMed2004

Fetal brain MRI: segmentation and biometric analysis of the posterior fossa.

This paper presents a novel approach to fetal magnetic resonance image segmentation and biometric analysis of the posterior fossa's midline structures. We developed a semi-automatic segmentation method (based on a region growing technique) and tested the algorithm on images of 104 normal fetuses. Using the segmented regions of interest (posterior fossa, vermis, and brainstem), we computed four relative area ratios. Statistical and clinical analysis of our results showed that the relative development of these structures appears to be independent of pregnancy term. In an additional study of 23 pathological cases, one of the four measurements was always significantly different from the corresponding value observed in normal cases.

Algorithms↗
PubMed2005

Dental biometrics: alignment and matching of dental radiographs.

Dental biometrics utilizes dental radiographs for human identification. The dental radiographs provide information about teeth, including tooth contours, elative positions of neighboring teeth, and shapes of the dental work (e.g., crowns, fillings, and bridges). The proposed system has two main stages: feature extraction and matching. The feature extraction stage uses anisotropic diffusion to enhance the images and a Mixture of Gaussians model to segment the dental work. The matching stage has three sequential steps: tooth-level matching, computation of image distances, and subject identification. In the tooth-level matching step, tooth contours are matched using a shape registration method, and the dental work is matched on overlapping areas. The distance between the tooth contours and the distance between the dental work are then combined using posterior probabilities. In the second step, the tooth correspondences between the given query (postmortem) radiograph and the database (antemortem) radiograph are established. A distance based on the corresponding teeth is then used to measure the similarity between the two radiographs. Finally, all the distances between the given postmortem radiographs and the antemortem radiographs that provide candidate identities are combined to establish the identity of the subject associated with the postmortem radiographs.

Algorithms↗
PubMed2007

Performance generalization in biometric authentication using joint user-specific and sample bootstraps.

Biometric authentication performance is often depicted by a detection error trade-off (DET) curve. We show that this curve is dependent on the choice of samples available, the demographic composition and the number of users specific to a database. We propose a two-step bootstrap procedure to take into account the three mentioned sources of variability. This is an extension to the Bolle et al.'s bootstrap subset technique. Preliminary experiments on the NIST2005 and XM2VTS benchmark databases are encouraging, e.g., the average result across all 24 systems evaluated on NIST2005 indicates that one can predict, with more than 75 percent of DET coverage, an unseen DET curve with eight times more users. Furthermore, our finding suggests that with more data available, the confidence intervals become smaller and, hence, more useful.

Algorithms↗
PubMed2004

Combination of hyperbolic functions for multimodal biometrics data fusion.

In this paper, we treat the problem of combining fingerprint and speech biometric decisions as a classifier fusion problem. By exploiting the specialist capabilities of each classifier, a combined classifier may yield results which would not be possible in a single classifier. The Feedforward Neural Network provides a natural choice for such data fusion as it has been shown to be a universal approximator. However, the training process remains much to be a trial-and-error effort since no learning algorithm can guarantee convergence to optimal solution within finite iterations. In this work, we propose a network model to generate different combinations of the hyperbolic functions to achieve some approximation and classification properties. This is to circumvent the iterative training problem as seen in neural networks learning. In many decision data fusion applications, since individual classifiers or estimators to be combined would have attained a certain level of classification or approximation accuracy, this hyperbolic functions network can be used to combine these classifiers taking their decision outputs as the inputs to the network. The proposed hyperbolic functions network model is first applied to a function approximation problem to illustrate its approximation capability. This is followed by some case studies on pattern classification problems. The model is finally applied to combine the fingerprint and speaker verification decisions which show either better or comparable results with respect to several commonly used methods.

Algorithms↗
PubMed2000

The problematic unity of biometrics.

The word "biometry" may be less than 200 years old, but it can be argued that work we would now consider biometric dates back even to the pre-Christian era. The unity of biometry is attested through examples spanning two millennia, and a lesson from Francis Galton is recalled from a century ago.

Biometry↗
PubMed2000

A century of biometrical genetics.

We briefly review the major contribution of biometrics to genetics over the last century (population genetic models, familial correlations, segregation analysis, and gene mapping) and current areas of active research and then speculate about what problems will be tackled in the next century.

Biometry↗
PubMed2005

Biometry, biometrics, biostatistics, bioinformatics,..., bio-X.

Recent scientific evolutions force us to rethink our profession's position on the scientific map, in relation to our neighboring professions, the ones with which we traditionally have strong collaborative links as well as the newly emerging fields, but also within our own, diverse professional group. We will show that great inspiration can be drawn from our own history, in fact from the early days of the Society. A recent inspiring example has been set by the late Rob Kempton, who died suddenly just months before he was to become President of the International Biometric Society.

Biometry↗