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PubMed2003

Determination of half-life and photon emission probabilities of (65)Zn.

A (65) Zn radioactive solution standardized by an absolute measurement method at Laboratoire National Henri Becquerel (LNHB), was sent to Bureau International des Poids et Mesures (BIPM), in order to include the results in their database. The activity value determined at BIPM was in good agreement with that stated by LNHB (the difference was 0.3%). Additional measurements of (65) Zn activity and half-life were also carried out, by using a 4pigamma ionization chamber; the half-life value proposed by this work: 244.15 (10) days, is consistent to others reported in the literature. The spectra analysis was performed by gamma-ray spectrometry with high-purity germanium detectors, with the aim to improve the accuracy of the photon emission probabilities values of this nuclide. The determined photon emission probabilities are 0.498 for the 1115 ke V gamma-ray, 0.347 and 0.0479 for the X-rays Cu-K(alpha) and Cu-K(beta); the associated uncertainties are 0.4%, 0.9% and 1.1%, respectively.

Gamma Rays↗

PubMed2000

Precise measurements of the gamma-ray emission probabilities of 186Re and 188Re.

Gamma-ray emission probabilities of 186Re and 188Re are important in nuclear medicine, and have been precisely measured by 4pibeta-gamma coincidence using a live-timed two-dimensional data-acquisition system. The gamma-ray emission probabilities of the 137.2 keV for 186Re and 155.1 keV for 188Re were 0.09487+/-0.00029 and 0.15425+/-0.00072, respectively.

Gamma Rays↗

PubMed1997

Performance characteristics of a new automated enzyme immunoassay for the measurement of allergen-specific IgE. Summary of the probability outcomes comparing results of allergen skin testing to results obtained with the HYTEC system and CAP system.

BACKGROUND: Measurement of allergen-specific IgE may assist in the diagnosis of allergy in selected patients. The development of new assays for determination of allergen-specific IgE should be optimized with respect to analytical sensitivity, precision, automation, and reporting of test results in mass units. OBJECTIVE: The objectives of this study were to evaluate the analytical performance of the new automated HYTEC method for the measurement of allergen-specific IgE and to compare the performance of this new assay to that of the Pharmacia CAP system. METHODS: To demonstrate parallelism, allergen-specific IgE dilution curves were generated by diluting four patient sera containing cat (19.8 kU/L), D. pteronyssinus (5.4 kU/L), birch pollen (2.6 kU/L), and timothy grass (1.0 kU/L) with equine serum. The precision study utilized sera from three different atopic donors with low levels (0.62 +/- 0.05 kU/L), moderate levels (1.45 +/- 0.18 kU/L), and high levels (13.59 +/- 0.89 kU/L) of allergen-specific IgE to three common inhalant allergens: D. pteronyssinus, timothy grass, and birch. Sera for outcome probability determinations were obtained from 54 patients who were evaluated for the presence of inhalant allergy by skin prick test and physical examination. Only sera from patients with at least one positive skin prick test that clinically correlate with the physician's evaluation of case history and physical examination were selected for study material. In this study, sensitivity and specificity are conditional probabilities describing performances of the CAP system and the HYTEC system to skin prick testing. The lowest threshold, 0.35 kU/L, recommended for detection of allergen-specific IgE was used for both systems. RESULTS: The HYTEC system accurately detected a reduction in allergen-specific IgE antibody with different serum concentrations of allergen-specific IgE ranging from 0.10 kU/L to 20 kU/L. The median interdilutional coefficient of variation of 12.5% was obtained with assay samples containing 19.8 to 0.1 kU/L allergen-specific IgE antibody. During a 20-day trial period, three standard allergen-specific IgE controls, 0.62, 1.45 and 13.39 kU/L, respectively, demonstrated a mean coefficient of variation less than 18%. In 20% of the patients, duplicate assay determinations of allergen-specific IgE measurements resulted in a one-class discrepancy in the lowest assay range, 0.35 to 0.70 kU/L, only. The correlation coefficient between the HYTEC and CAP allergen-specific IgE assays was 0.77, rank correlation coefficients, being allergen-dependent and ranging from 0.62 to 0.91. Allergen-specific IgE assay sensitivity of the HYTEC system ranged from 0.78 to 1.00, whereas the assay sensitivity for the CAP system ranged from 0.50 to 1.00. Assay specificity ranged from 0.66 to 0.93 for the HYTEC system and from 0.70 to 0.87 for the CAP system. Eighty-nine percent of HYTEC-positive patients had a positive skin prick test (3% standard error) and 87% of CAP-positive patients had a positive skin prick test (4% standard error). Ninety-two percent of HYTEC-negative patients had a negative skin prick test (4% standard error), whereas 76% of CAP-negative patients had a negative skin prick test (5% standard error). CONCLUSION: The HYTEC system fulfills the current analytical requirements necessary to measure allergen-specific IgE antibody quantitatively and qualitatively, and compares favorably in performance with the CAP system.

Allergens↗

PubMedDate not supplied

Paternity probability when a relative of the father is an alleged father.

When scientists use DNA evidence in court, coancestry effects such as population structure and relatedness are usually ignored. In paternity cases, only if a particular man has the child's paternal allele at a certain locus, can he not be excluded in the paternity dispute. However, it is certainly true that close relatives will be far more likely to have the child's paternal allele than will random members of the reference population. In particular, the probability that the true father's brother has the paternal allele is very much greater than that for any other relationship. In this paper, the authors describe a method for inference in a case where the true father may be a relative of the alleged father. This paper also reports that most current methods overstate the probability that the alleged father is the father.

Alleles↗

PubMed2000

Transition probabilities and average cross sections for the Na2 B1pi(u) --> X1sigma(g)+ system using as excitation the 4880 A Ar+ laser line.

The fluorescence spectrum of Na2 induced by the 4879.86 A line of an Argon ion laser has been analyzed with special emphasis on determination of accurate relative intensities. We have observed nineteen fluorescence series for the B1pi(u) --> X1sigma(g)+ band system. Some series are reported for the first time. The radiative transition probabilities for the observed fluorescence series were calculated using hybrid potential energy curves for the B1pi(u) and X1sigma(g)+ states constructed up to dissociation and a B-X transition dipole moment function. Radiative lifetimes for the rovibrational levels of the upper states pumped by the laser line have also been calculated. The transition probabilities and lifetimes agree with the corresponding observed measurements usually within the experimental uncertainty. From the rotational satellite structure with deltaJ' = +/- 1, +/- 2...+/- 20, for some nu''-bands of the most intense fluorescence series induced by emission from the vibrational-rotational levels: nu' = 6, J' = 43 and v' = 9, J' = 56, collision-induced transition rates and average cross sections have been obtained.

Argon↗

PubMed1983

A note on ascertainment probability in the Allen/Hrubec twin model.

In their general model of twin concordance Allen and Hrubec recently introduced the concept of secondary ascertainment rate to consider partial ascertainment of secondary cases. This concept is found to be of limited interest because only pairs where valid information can be obtained from both twins should be included in genetic analyses. It is furthermore shown that the validity of the proband method and the Allen/Hrubec model depends on the equivalence of ascertainment in twins from concordant and discordant pairs. However, if this condition is fulfilled, it has been shown how the ascertainment probability in cotwins of probands is related to the overall ascertainment probability in the total population.

Diseases in Twins↗

PubMed2002

A method for computing identity by descent probabilities and quantitative trait loci mapping with dominant (AFLP) markers.

Amplified fragment length polymorphisms (AFLPs) are a widely used marker system: the technique is very cost-effective, easy and rapid, and reproducibly generates hundreds of markers. Unfortunately, AFLP alleles are typically scored as the presence or absence of a band and, thus, heterozygous and dominant homozygous genotypes cannot be distinguished. This results in a significant loss of information, especially as regards mapping of quantitative trait loci (QTLs). We present a Monte Carlo Markov Chain method that allows us to compute the identity by descent probabilities (IBD) in a general pedigree whose individuals have been typed for dominant markers. The method allows us to include the information provided by the fluorescent band intensities of the markers, the rationale being that homozygous individuals have on average higher band intensities than heterozygous individuals, as well as information from linked markers in each individual and its relatives. Once IBD probabilities are obtained, they can be combined into the QTL mapping strategy of choice. We illustrate the method with two simulated populations: an outbred population consisting of full sib families, and an F2 cross between inbred lines. Two marker spacings were considered, 5 or 20 cM, in the outbred population. There was almost no difference, for the practical purpose of QTL estimation, between AFLPs and biallelic codominant markers when the band density is taken into account, especially at the 5 cM spacing. The performance of AFLPs every 5 cM was also comparable to that of highly polymorphic markers (microsatellites) spaced every 20 cM. In economic terms, QTL mapping with a dense map of AFLPs is clearly better than microsatellite QTL mapping and little is lost in terms of accuracy of position. Nevertheless, at low marker densities, AFLPs or other biallelic markers result in very inaccurate estimates of QTL position.

Algorithms↗

PubMed1999

The usefulness of partial information: effects of go probability in the choice/Nogo task.

In the present study, we examined whether the use of partial information for response preparation depends on the utility of that partial information for meeting task demands. Using a choice/Nogo task, the utility of the partial information was varied by manipulating the proportion of Go relative to Nogo signals, and preliminary response preparation was indexed by the degree of lateralized readiness potential (LRP) activity on Nogo trials. The Nogo LRP was clearly present when Go probability was high (67% Go) and, to a lesser extent, when Go and Nogo signals were equiprobable. However, the Nogo LRP disappeared when the probability of a Go signal was low (25% Go). This pattern of results supports the hypothesis that response preparation will be based on partial stimulus information only when the information has significant utility in the context of the overall task requirements.

Adult↗

PubMed2004

Physicochemical properties determining the detection probability of tryptic peptides in Fourier transform mass spectrometry. A correlation study.

Sequence verification and mapping of posttranslational modifications require nearly 100% sequence coverage in the "bottom-up" protein analysis. Even in favorable cases, routine liquid chromatography-mass spectrometry detects from protein digests peptides covering 50-90% of the sequence. Here we investigated the reasons for limited peptide detection, considering various physicochemical aspects of peptide behavior in liquid chromatography-Fourier transform mass spectrometry (LC-FTMS). No overall correlation was found between the detection probability and peptide mass. In agreement with literature data, the signal increased with peptide hydrophobicity. Surprisingly, the pI values exhibited an opposite trend, with more acidic tryptic peptides detected with higher probability. A mixture of synthesized peptides of similar masses confirmed the hydrophobicity dependence but showed strong positive correlation between pI and signal response. An explanation of this paradoxal behavior was found through the observation that more acidic tryptic peptide lengths tend to be longer. Longer peptides tend to acquire higher average charge state in positive mode electrospray ionization than more basic but shorter counterparts. The induced-current detection in FTMS favors ions in higher charge states, thus providing the observed pI-FTMS signal anticorrelation.

Animals↗

PubMedDate not supplied

Probability of conception on different days of the menstrual cycle: an ongoing exercise.

The design of the European Multicenter Study on the probabilities of conception in different days of the menstrual cycle is reviewed. Some results, based on part of the data, are presented. These can be summarized as follows: a) Estimates of the probabilities of conception are lower than the ones previously reported in the literature; b) A strong effect of the man's age on fecundability was found. No evidence of a similar impact of the woman's age was demonstrated; c) The number of days with 'most fertile' mucus and parity affect fecundability.

Aging↗

PubMed2005

Inconsistent probability estimates of a hypothesis: the role of contrasting support.

This paper studies consistency in the judged probability of a target hypothesis in lists of mutually exclusive nonexhaustive hypotheses. Specifically, it controls the role played by the support of displayed competing hypotheses and the relatedness between the target hypothesis and its alternatives. Three experiments are reported. In all experiments, groups of people were presented with a list of mutually exclusive nonexhaustive causes of a person's death. In the first two experiments, they were asked to judge the probability of each cause as that of the person's decease. In the third experiment, people were asked for a frequency estimation task. Target causes were presented in all lists. Several other alternative causes to the target ones differed across the lists. Findings show that the judged probability/frequency of a target cause changes as a function of the support of the displayed competing causes. Specifically, it is higher when its competing displayed causes have low rather than high support. Findings are consistent with the contrastive support hypothesis within the support theory.

Humans↗

PubMed1996

The magical number .7 +/- .2: meta-meta-analysis of the probability of superior outcome in comparisons involving therapy, placebo, and control.

The "probability of superiority estimate" (PS) estimates the probability that a randomly sampled client from a population given a treatment will have an outcome that is superior to that of a randomly sampled client from a population given another treatment. The meta-analytic clinical outcome literature was examined to calculate mean PS (PS) for comparisons involving therapy versus control, therapy versus placebo, therapy versus therapy, and placebo versus control. The range of PS was found to be approximately .7 +/- .2, with median PS greatest when therapy and control are compared (Mdn PSTC = .70, where T = therapy and C = control) and least when 2 therapies are compared (Mdn PSTT = .56). Results suggested that there is more to therapeutic success than placebo effects (Mdn PSTP = .66, where T = therapy and P = placebo) and that placebo is typically better than do-nothing control conditions (Mdn PSPC = .62). The present exceptionally large study, controlling for dependencies and confounding variables, may put to rest the question of the superiority of therapy to placebo. It also appears that the strength of effect of therapy is typically at least average among the effects of independent variables in psychology.

Adult↗

PubMed2003

A critique of Oaksford, Chater, and Larkin's (2000) conditional probability model of conditional reasoning.

M. Oaksford, N. Chater, and J. Larkin (2000) proffered a Bayesian model in which conditional inferences are a direct function of conditional probabilities. In the current article, the authors first considered this model regarding the processing of negatives in conditional reasoning. Its predictions were evaluated against a large-scale meta-analysis (W. J. Schroyens, W. Schaeken, & G. d'Ydewalle, 2001b). This evaluation shows that the model is flawed: The relative size of the negative effects does not match predictions. Next, the authors evaluated the model in relation to inferences about affirmative conditionals, again considering the results of a meta-analysis (W. J. Schroyens, W. Schaeken, & G. d'Ydewalle, 2001a). The conditional probability model is countered by the data reported in literature; a mental models based model produces a better fit. The authors conclude that a purely probabilistic model is deficient and incomplete and cannot do without algorithmic processing assumptions if it is to advance toward a descriptively adequate psychological theory.

Conditioning, Psychological↗

PubMed2005

Finding useful questions: on Bayesian diagnosticity, probability, impact, and information gain.

Several norms for how people should assess a question's usefulness have been proposed, notably Bayesian diagnosticity, information gain (mutual information), Kullback-Liebler distance, probability gain (error minimization), and impact (absolute change). Several probabilistic models of previous experiments on categorization, covariation assessment, medical diagnosis, and the selection task are shown to not discriminate among these norms as descriptive models of human intuitions and behavior. Computational optimization found situations in which information gain, probability gain, and impact strongly contradict Bayesian diagnosticity. In these situations, diagnosticity's claims are normatively inferior. Results of a new experiment strongly contradict the predictions of Bayesian diagnosticity. Normative theoretical concerns also argue against use of diagnosticity. It is concluded that Bayesian diagnosticity is normatively flawed and empirically unjustified.

Bayes Theorem↗

PubMed2001

Implicit learning of first-, second-, and third-order transition probabilities.

Most sequence-learning studies have confounded different types of information, making it difficult to know precisely what is learned. Addressing many of the confounds, the current study shows that people can learn 1st-, 2nd-, and 3rd-order transition probabilities. Measures directly assessing awareness of the probabilities show that the knowledge is implicit early in training and becomes explicit with extended training.

Adolescent↗

PubMed1980

Determining the probability of an important difference in bioavailability.

Bioavailability studies usually compare formulations of a drug under the premise of equal bioavailabilities. Analyses of such studies may be questioned when large differences exist, but are not statistically significant, or when small differences are found which do reach statistical significance. In either case, the question of clinical significance is not addressed and remains problematic regardless of the outcome. The important question is, "Given the results of the study, what is the probability that a clinically important difference exists?" To obviate dependence on statistical significance, we propose a methodology which permits computation of the probability that a clinically important difference in bioavailability exists between two products, regardless of the results of conventional tests of hypothesis. The methodology permits a strong statement which defines the likelihood of a meaningful difference, rather than the "nonstatement" of current approaches. The approach is illustrated by a study in which a 2% (nonsignificant) difference in bioavailability was observed. Using the proposed methodology the analysis concluded that the odds are about 5 to 1 against there being a 20% difference in bioavailability between the formulations.

Bayes Theorem↗

PubMed2006

A probability-based approach for high-throughput protein phosphorylation analysis and site localization.

Data analysis and interpretation remain major logistical challenges when attempting to identify large numbers of protein phosphorylation sites by nanoscale reverse-phase liquid chromatography/tandem mass spectrometry (LC-MS/MS) (Supplementary Figure 1 online). In this report we address challenges that are often only addressable by laborious manual validation, including data set error, data set sensitivity and phosphorylation site localization. We provide a large-scale phosphorylation data set with a measured error rate as determined by the target-decoy approach, we demonstrate an approach to maximize data set sensitivity by efficiently distracting incorrect peptide spectral matches (PSMs), and we present a probability-based score, the Ascore, that measures the probability of correct phosphorylation site localization based on the presence and intensity of site-determining ions in MS/MS spectra. We applied our methods in a fully automated fashion to nocodazole-arrested HeLa cell lysate where we identified 1,761 nonredundant phosphorylation sites from 491 proteins with a peptide false-positive rate of 1.3%.

Algorithms↗

PubMed1989

Probability and sampling.

The concept of probability is introduced, and the role of probability distributions in statistical theory is discussed, with particular reference to the Normal distribution and its characteristics. Sampling and sampling variation are described, together with sampling error, the standard error of the mean, and confidence intervals for determining the likely magnitude of a population mean.

Child↗