Search results for "statistical [methods]"
showing 10 items of 1664 documents
Influence of temperature on the calibration curves in IRMA for neuron specific enolase and its physicochemical interpretation
2009
Abstract Background immunoradiometric assay (IRMA) is one of the principal methods used for the analytical determination of neuron specific enolase (NSE) concentration. We studied the influence of temperature on the calibration curves obtained by this method, and a physicochemical justification based on two theoretical models is proposed. Material and methods we used a commercially available RIA kit for NSE and a gamma counter. Data was analysed using Statistical software. Results and discussion activity bound to the antibody increases with temperature, producing results that are consistent with two modifications to the four parameter and Langmuir equations. Conclusions the two models used …
Intraosseous monitoring of drilling in lumbar vertebrae by ultrasound: An experimental feasibility study.
2016
The rationale for this project is to evaluate the efficiency of a novel sonographic method for measurements of interosseous distances. The method utilizes a propagating ultrasonic beam through aqueous milieu which is directed as a jet into a drilled tract. We used a plastic model of human L5 vertebra and ex vivo specimen of L5 porcine vertebra and generated 2 mm in diameter tracts in vertebral pedicles. The tracts were created in the "desired" central direction and in the "wrong" medial and lateral directions. The drilled tracts and the residual, up to opposite cortex, distances were measured sonographically and mechanically and compared statistically. We show that "true" mechanical measure…
Monte Carlo Tests of Nucleation Concepts in the Lattice Gas Model
2013
The conventional theory of homogeneous and heterogeneous nucleation in a supersaturated vapor is tested by Monte Carlo simulations of the lattice gas (Ising) model with nearest-neighbor attractive interactions on the simple cubic lattice. The theory considers the nucleation process as a slow (quasi-static) cluster (droplet) growth over a free energy barrier $\Delta F^*$, constructed in terms of a balance of surface and bulk term of a "critical droplet" of radius $R^*$, implying that the rates of droplet growth and shrinking essentially balance each other for droplet radius $R=R^*$. For heterogeneous nucleation at surfaces, the barrier is reduced by a factor depending on the contact angle. U…
Statistics of reversible transitions in two-state trajectories in force-ramp spectroscopy
2014
A possible way to extract information about the reversible dissociation of a molecular adhesion bond from force fluctuations observed in force ramp experiments is discussed. For small loading rates the system undergoes a limited number of unbinding and rebinding transitions observable in the so-called force versus extension (FE) curves. The statistics of these transient fluctuations can be utilized to estimate the parameters for the rebinding rate. This is relevant in the experimentally important situation where the direct observation of the reversed FE-curves is hampered, e.g. due to the presence of soft linkers. I generalize the stochastic theory of the kinetics in two-state models to the…
Mechanically interlocked calix[4]arene dimers display reversible bond breakage under force.
2009
The physics of nanoscopic systems is strongly governed by thermal fluctuations that produce significant deviations from the behaviour of large ensembles1,2. Stretching experiments of single molecules offer a unique way to study fundamental theories of statistical mechanics, as recently shown for the unzipping of RNA hairpins3. Here, we report a molecular design based on oligo calix[4]arene catenanes—calixarene dimers held together by 16 hydrogen bridges—in which loops within the molecules limit how far the calixarene nanocapsules can be separated. This mechanically locked structure tunes the energy landscape of dimers, thus permitting the reversible rupture and rejoining of the individual n…
Single-layer metal-on-metal islands driven by strong time-dependent forces
2012
Non-linear transport properties of single-layer metal-on-metal islands driven with strong static and time-dependent forces are studied. We apply a semi-empirical lattice model and use master equation and kinetic Monte Carlo simulation methods to compute observables such as the velocity and the diffusion coefficient. Two types of time-dependent driving are considered: a pulsed rotated field and an alternating field with a zero net force (electrophoretic ratchet). Small islands up to 12 atoms were studied in detail with the master equation method and larger ones with simulations. Results are presented mainly for a parametrization of Cu on Cu(001) surface, which has been the main system of int…
Novel 3D bio-macromolecular bilinear descriptors for protein science: Predicting protein structural classes
2015
In the present study, we introduce novel 3D protein descriptors based on the bilinear algebraic form in the ℝn space on the coulombic matrix. For the calculation of these descriptors, macromolecular vectors belonging to ℝn space, whose components represent certain amino acid side-chain properties, were used as weighting schemes. Generalization approaches for the calculation of inter-amino acidic residue spatial distances based on Minkowski metrics are proposed. The simple- and double-stochastic schemes were defined as approaches to normalize the coulombic matrix. The local-fragment indices for both amino acid-types and amino acid-groups are presented in order to permit characterizing fragme…
Permutation Test (PT) and Tolerated Difference Test (TDT): Two new, robust and powerful nonparametric tests for statistical comparison of dissolution…
2013
The most popular way of comparing oral solid forms of drug formulations from different batches or manufacturers is through dissolution profile comparison. Usually, a similarity factor known as (f2) is employed; However, the level of confidence associated with this method is uncertain and its statistical power is low. In addition, f2 lacks the flexibility needed to perform in special scenarios. In this study two new statistical tests based on nonparametrical Permutation Test theory are described, the Permutation Test (PT), which is very restrictive to confer similarity, and the Tolerated Difference Test (TDT), which has flexible restrictedness to confer similarity, are described and compared…
Six-month healing success rates after endodontic treatment using the novel GentleWave System: the pure prospective multi-center clinical study
2015
Background This prospective multi-center (PURE) clinical study evaluated healing rates for molars after root canal treatment employing the GentleWave® System (Sonendo, Inc., Laguna Hills, CA). Material and Methods Eighty-nine patients met the inclusion criteria and consented for this clinical study after referral for a root canal treatment. All enrolled patients were treated with the GentleWave System. Five endodontists performed the clinical procedures and follow-up evaluations. Pre-operative, intra-operative, and post-operative data were collected from the consented patients. Each patient was evaluated for clinical signs and symptoms. Two trained, blinded, and independent evaluators score…
Evaluation of the agreement by examiners according to classifications of third molars
2011
Objectives. This study recorded and evaluated the intra- and inter-group agreement degree by different examiners for the classification of lower third molars according to both the Winter’s and Pell & Gregory’s systems. Study Design. An observational and cross-sectional study was realized with forty lower third molars analyzed from twenty digital panoramic radiographs. Four examiner groups (undergraduates, maxillofacial surgeons, oral radiologists and clinical dentists) from Aracaju, Sergipe, Brazil, classified them in relation to angulation, class and position. The variance test (ANOVA) was applied in the examiner findings with significance level of p<0.05 and confidence intervals of 95%. R…