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Graphical Representation (graphical + representation)

Distribution by Scientific Domains

Chemistry	39%
Life Sciences	9%
Engineering	9%
Psychology	6%
Medical Sciences	6%
Business, Economics, Finance and Accounting	6%
6 Other Domains	25%

Selected Abstracts

Graphing survival curve estimates for time-dependent covariates

INTERNATIONAL JOURNAL OF METHODS IN PSYCHIATRIC RESEARCH, Issue 2 2002
Lonni R. Schultz
Abstract Graphical representation of statistical results is often used to assist readers in the interpretation of the findings. This is especially true for survival analysis where there is an interest in explaining the patterns of survival over time for specific covariates. For fixed categorical covariates, such as a group membership indicator, Kaplan-Meier estimates (1958) can be used to display the curves. For time-dependent covariates this method may not be adequate. Simon and Makuch (1984) proposed a technique that evaluates the covariate status of the individuals remaining at risk at each event time. The method takes into account the change in an individual's covariate status over time. The survival computations are the same as the Kaplan-Meier method, in that the conditional survival estimates are the function of the ratio of the number of events to the number at risk at each event time. The difference between the two methods is that the individuals at risk within each level defined by the covariate is not fixed at time 0 in the Simon and Makuch method as it is with the Kaplan-Meier method. Examples of how the two methods can differ for time dependent covariates in Cox proportional hazards regression analysis are presented. Copyright © 2002 Whurr Publishers Ltd. [source]

Effect of variable message signs on driver speed behavior on a section of expressway under adverse fog conditions,A driving simulator approach

JOURNAL OF ADVANCED TRANSPORTATION, Issue 1 2006
V. Ganesh Babu Kolisetty
Abstract Variable message signs (VMS) are used to provide dynamic information and one current application is to show different speed limits under different conditions. As speed is an important contributor to road accidents and also affects driver speed behavior, the present study focuses on how effective traffic advisory information is when helping drivers to divert from potentially dangerous conditions. Graphical representation of an Expressway section made it easy to isolate the effects of speed etc. by drivers with information provided through VMS under adverse fog conditions. Understanding and reacting to the VMS system by drivers is essential for its success. If drivers do not react by changing speed behavior then the VMS system will fail and further implementation may cease. In this paper an Analysis of Variance model, which is appropriate to the proposed experimental conditions, is used to study how subjects (drivers) will perceive provided information and also to find the effect of VMS on driver speed behavior on the simulated Expressway section. [source]

A Screen Space Quality Method for Data Abstraction

COMPUTER GRAPHICS FORUM, Issue 3 2008
J. Johansson
Abstract The rendering of large data sets can result in cluttered displays and non-interactive update rates, leading to time consuming analyses. A straightforward solution is to reduce the number of items, thereby producing an abstraction of the data set. For the visual analysis to remain accurate, the graphical representation of the abstraction must preserve the significant features present in the original data. This paper presents a screen space quality method, based on distance transforms, that measures the visual quality of a data abstraction. This screen space measure is shown to better capture significant visual structures in data, compared with data space measures. The presented method is implemented on the GPU, allowing interactive creation of high quality graphical representations of multivariate data sets containing tens of thousands of items. [source]

Kinematics, Dynamics, Biomechanics: Evolution of Autonomy in Game Animation

COMPUTER GRAPHICS FORUM, Issue 3 2005
Steve Collins
The believeable portrayal of character performances is critical in engaging the immersed player in interactive entertainment. The story, the emotion and the relationship between the player and the world they are interacting within are hugely dependent on how appropriately the world's characters look, move and behave. We're concerned here with the character's motion; with next generation game consoles like Xbox360TM and Playstation®3 the graphical representation of characters will take a major step forward which places even more emphasis on the motion of the character. The behavior of the character is driven by story and design which are adapted to game context by the game's AI system. The motion of the characters populating the game's world, however, is evolving to an interesting blend of kinematics, dynamics, biomechanics and AI drivenmotion planning. Our goal here is to present the technologies involved in creating what are essentially character automata, emotionless and largely brainless character shells that nevertheless exhibit enough "behavior" to move as directed while adapting to the environment through sensing and actuating responses. This abstracts the complexities of low level motion control, dynamics, collision detection etc. and allows the game's artificial intelligence system to direct these characters at a higher level. While much research has already been conducted in this area and some great results have been published, we will present the particular issues that face game developers working on current and next generation consoles, and how these technologies may be integrated into game production pipelines so to facilitate the creation of character performances in games. The challenges posed by the limited memory and CPU bandwidth (though this is changing somewhat with next generation) and the challenges of integrating these solutions with current game design approaches leads to some interesting problems, some of which the industry has solutions for and some others which still remain largely unsolved. [source]

Volatile compounds after spontaneous fermentation of musts from Vitis vinifera cv. Albariño grapes cultivated in different origins from Rías Baixas AOC, Spain

FLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2006
S. Zamúz
Abstract White wines experimentally produced from the white grape variety Albariño from three different areas from Rias Baixas AOC, north-western Spain, have been analysed in this study. The contents of terpenes, C13 -norisoprenoids, alcohols, acetates and ethyl esters were determined by GC,MS. The Albariño wines from O Rosal are characterized by a high content of higher alcohols, while wines from Val do Salnés show the highest concentrations of free terpenes, acetates and ethyl esters; and wines of Condado do Tea show the highest concentrations of C13 -norisoprenids, principally due to the ,-ionone. Two principal components accounting for 90.7% of the total variance were calculated by means of a principal components analysis (PCA), and the graphical representation of these two components allows grouping the wines according their respective origins. Volatile compounds with fruity and floral odours showed the highest odour activity values, contributing in a great measure to the aroma of Albariño wines. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Nanofibers from Laser Spinning: Laser Spinning of Bioactive Glass Nanofibers (Adv. Funct.

ADVANCED FUNCTIONAL MATERIALS, Issue 19 2009
Mater.
This cover image is a graphical representation of the laser spinning process described by Félix Quintero et al. on page 3084. Laser spinning involves the use of a high power laser to melt a very small volume from a plate of the precursor material. A high speed supersonic gas jet causes the rapid elongation and cooling of the melt, yielding a glass nanofiber. The authors also describe the use of this technique in producing Bioglass nanofibers. [source]

Modelling the hydrology of a catchment using a distributed and a semi-distributed model

HYDROLOGICAL PROCESSES, Issue 3 2005
Ahmed Abu El-Nasr
Abstract Various hydrological models exist that describe the phases in the hydrologic cycle either in an empirical, semi-mechanistic or fully mechanistic way. The way and level of detail for the different processes of the hydrologic cycle that needs to be described depends on the objective, the application and the availability of data. In this study the performance of two different models, the fully distributed MIKE SHE model and the semi-distributed SWAT model, was assessed. The aim of the comparative study was to examine if both models are equally able to describe the different phases in the hydrologic cycle of a catchment, given the availability of hydrologic data in the catchment. For the comparison, historic data of the Jeker river basin, situated in the loamy belt region of Belgium, was used. The size of the catchment is 465 km2. The landscape is rolling, the dominant land use is farmland, and the soils vary from sandy-loam to clay-loam. The daily data of a continuous period of 6 years were used for the calibration and validation of both models. The results were obtained by comparing the performance of the two models using a qualitative (graphical) and quantitative (statistical) assessment, such as graphical representation of the observed and simulated river discharge, performance indices, the hydrograph maxima, the baseflow minima, the total accumulated volumes and the extreme value distribution of river flow data. The analysis revealed that both models are able to simulate the hydrology of the catchment in an acceptable way. The calibration results of the two tested models, although they differ in concept and spatial distribution, are quite similar. However, the MIKE SHE model predicts slightly better the overall variation of the river flow. Copyright © 2005 John Wiley & Sons, Ltd. [source]

A 3D graphical representation of DNA sequence based on numerical coding method

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 5 2010
Zhi Cao
Abstract Recently, we introduced a sort of numerical coding method of DNA sequences (Chen et al., MATCH Commun Math Comput Chem, 2008, 60, 291). On the basis of the result of our coding method, we present a 3D graphical representation of DNA sequences. The 3D graphical representation also avoids loss of information accompanying alternative 2D and 3D representation in which the curve standing for DNA overlaps and intersects itself. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source]

A graphical method to construct a phylogenetic tree

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 9 2006
Weiping Wang
Abstract A 3D graphical representation of DNA sequences, which has no circuit or degeneracy, is derived for mathematical denotation of DNA sequence. Based on this graphical representation, we propose a new sequence distance measure. We make use of the corresponding similarity matrix to construct a phylogenic tree by virtue of the fuzzy theory. The examination of phylogenic tree belong to eight species illustrates the utility of our approach. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source]

RNA secondary structure 2D graphical representation without degeneracy

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 8 2006
Bo Liao
Abstract A two-dimensional graphical representation (2DGRR) of RNA secondary structures using a two Cartesian coordinates system has been derived for mathematical denotation of RNA structure. The 2DGRR resolves structure degeneracy and avoids loss of information and the limitation that different structures correspond to the same curve. The RNA pseudo-knots also can be represented as 2D graphical representations. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source]

Conversations in conservation: revealing and dealing with language differences in environmental conflicts

JOURNAL OF APPLIED ECOLOGY, Issue 4 2008
Thomas J. Webb
Summary 1Applied ecology aims to translate research into policy recommendations. However, conflicts frequently develop if these recommendations propose a contentious course of action. A first step towards addressing such conflicts is to attempt to understand the values underpinning stakeholder viewpoints. 2We develop a computer-aided Content Analysis to analyse the language surrounding environmental conflicts for insights into stakeholder values. Using the conflict arising over proposals to cull hedgehogs Erinaceus europaeus on several Scottish islands, we show how different stakeholder groups frame the problem in different ways. 3Stakeholder groups supporting different courses of action (culling vs. translocating hedgehogs) use different arguments, the former emphasizing conservation and biodiversity, the latter focusing on animal welfare. Our method results in a graphical representation of this failure to agree on a common way to frame the issue. 4Including texts obtained from media sources illustrates how the media can exacerbate environmental conflicts through the issues they emphasize and the vocabulary they use. 5Synthesis and applications. Our method provides a simple means to quantify levels of stakeholder disagreement concerning potentially contentious environmental issues. Our results provide a starting point for the development of a quantitative, graphical tool for managers, where repeated analysis will aid in monitoring and managing conflicts. In addition, we provide a clear example of the role of societal attitudes influencing the effective implementation of ecological advice, which should encourage ecologists to become more aware of the social environment into which policy recommendations are to be launched and to ensure that their advice does not ignore important stakeholder values. [source]

Graphical approach to analyzing DNA sequences

JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 14 2005
Bo Liao
Abstract Recently, we proposed a 2D graphical representation of DNA sequence [J Comput Chem 25(2004) 1364,1368]. Based on this representation, we outline one approach to search optimal alignment. We also can judge the mutations between bases and an unknown sequence based on its graph and a known sequence's graph. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 1519,1523, 2005 [source]

A COMPARISON OF METHODS FOR MONITORING INDIVIDUAL PERFORMANCES IN TASTE SELECTION TESTS

JOURNAL OF SENSORY STUDIES, Issue 4 2005
AMALIA CALVIÑO
ABSTRACT The evaluation of panel performance was made by three methods: average of correct responses (A), comparison of distances of individual standardized judgments to the average standardized responses (D) and a principal components analysis (PCA). Thirty assessors identified water and basic tastes and discriminated different sweet stimuli in neutral or acidified vehicles using R-index rating and ranking tests. By A and D methods 22 assessors were qualified as proficient. Composition of both panels was identical except for one judge. The output from PCA provided a graphical representation of the performance of the assessors and retained different subsets of 24,26 panelists for different proposals as discrimination of sweetness in acidified beverages, recognition of bitterness, sourness and discrimination of slight sweetness or evaluation of saltiness. [source]

A COMPARISON OF METHODS FOR EVALUATING THE PERFORMANCE OF A TRAINED SENSORY PANEL,

JOURNAL OF SENSORY STUDIES, Issue 6 2001
MARJORIE C. KING
ABSTRACT Cluster analysis, consonance analysis, principal component analysis (PCA) and the GRAPES program (Schlich 1994) were compared for the evaluation of panel performance. Ten judges evaluated 25 Merlot wines for 24 color, aroma and flavor attributes. Cluster analysis grouped similar judges. PCA identified judges according to their attribute use. Consonance analysis determined a numerical index for attribute agreement and the GRAPES program compared judges in their use of the scale, reliability, discrimination and disagreement. Three of the four techniques provided a graphical representation of similarities and differences between judges. Methodologies were best used in conjunction with one another. Ultimately the application of these tools will serve to improve the quality of sensory evaluations. [source]

Long-term changes in the chromosomal inversion polymorphism of Drosophila subobscura.

JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 3 2004

Abstract The chromosomal polymorphism of 13 European populations of Drosophila subobscura has been compared with that of the same populations collected 15,35 years ago. The chromosomal polymorphism of the old populations differs significantly from that of the new populations, mainly for chromosomes U and O. There is a very good agreement between the geographical space and the genetic space as shown by a graphical representation of the 26 statistical populations (13 old and 13 new) obtained by a principal coordinate analysis. This reflects both the existence of significant latitudinal clines for the frequencies of some chromosomal arrangements in the old and new samples and systematic changes that have taken place in these populations during the period that elapsed between the two surveys. An increase in the frequency of those arrangements typical of southern latitudes and a decrease for those common in northern latitudes is observed in all populations , Mediterranean, Atlantic and Central European. Furthermore, the genetic distances of the new populations to a southern population of reference have decreased in comparison with those of the old populations. These changes could be the result of climatic factors that are correlated with latitude. In particular, the assumption that global warming is responsible for all the changes observed appears rather likely. Whether these systematic changes of the chromosomal polymorphism are a consequence of local adaptations or have been produced by migration from the south remains an open question. Zusamennfassung Der gegenwärtige chromosomale Inversionspolymorphismus in 13 europäischen Populationen von Drosophila subobscura wurde mit dem Zustand in denselben Populationen verglichen, die vor 15 bis 35 Jahren untersucht worden waren. Der Chromosomenpolymorphismus der ,,alten'' Populationen unterscheidet sich signifikant von dem der ,,neuen'' Populationen, besonders für die Chromosomen U und O. Eine sehr gute Übereinstimmung zeigt sich zwischen der geographischen Komponente und der genetischen Komponente bei einer graphischen Darstellung der 26 Populationen (13 alte und 13 neue Populationen) durch eine Koordinatenanalyse. Das spiegelt beides wider, die Existenz von signifikanten breitenabhängigen Klinen in der Häufigkeit einiger chromosomaler Strukturtypen in den alten und den neuen Populationen, aber auch die systematischen Änderungen, die sich bei diesen Populationen im Laufe der Zeit zwischen den beiden Untersuchungen ereignet haben. Eine Zunahme in den Häufigkeiten jener Chromosomenstrukturen, die typisch für südliche Breiten sind, und eine Abnahme solcher Strukturen, die häufig in nördliche Breiten sind, konnte beobachtet werden - in den mediterranen, den atlantischen und den mitteleuropäischen Populationen in der gleichen Weise. Außerdem haben die genetischen Distanzen der neuen Populationen zu einer südlichen Referenzpopulation im Vergleich zu denen der alten Populationen abgenommen. Diese Veränderungen wurden vermutlich von klimatischen Faktoren bestimmt, die mit der geographischen Breite korreliert sind. Insbesonders erscheint die Annahme, daß die globale Erwärmung für die Veränderungen des Chromosomenpolymorphismus dafür verantwortlich ist, ziemlich wahrscheinlich. Ob diese systematischen Transformationen des Chromosomenpolymorphismus ein Konsequenz lokaler Anpassungen oder auf Migration aus dem Süden zurückzuführen sind, bleibt eine offene Frage. [source]

A new algorithm to estimate aircraft icing in the HIRLAM model

METEOROLOGICAL APPLICATIONS, Issue 2 2003
Bernt Olofsson
A new index to estimate aircraft icing in clouds from operational meteorological models has been developed by Swedish meteorologists. Although rather simple it takes into account, directly or indirectly, all the principal meteorological variables for icing. The index has been evaluated during three winter seasons and is now operational in the Swedish HIRLAM model. A graphical representation of the index is presented. Copyright © 2003 Royal Meteorological Society [source]

A new standard for the assessment of disease progression in murine cutaneous leishmaniasis

PARASITE IMMUNOLOGY, Issue 5 2000
Lynden J.roberts
Infection of mice with Leishmania major has been used both as a model for the cutaneous disease in humans and as a model for the more general control and function of helper T cells in immunity. In both cases, disease patterns and disease progression have been assessed by two complementary methods, lesion size and parasite burden in the draining lymph nodes. We propose a much improved method for the graphical representation of lesion development which conveys more information with better accuracy. We also describe a polymerase chain reaction method for determining parasite burden, which is faster and allows the analysis of larger numbers of experimental animals than the current limiting dilution analysis. Moreover, these methods are equally applicable to other infectious diseases, an obvious one being schistosomiasis. [source]

Combining idiographic and nomothetic methods in the study of internal working models

PERSONAL RELATIONSHIPS, Issue 2 2000
WARREN A. REICH
Attachment theory's notion of internal working model refers to an affective,cognitive structure that guides how individuals experience, and act within, their close relationships. Understanding working models in general (i.e., nomothetically) can be greatly enhanced by attending to the unique (i.e., idiographic) properties of individuals'data. A general method is described for eliciting and empirically representing both the common and unique properties of individuals'descriptions of self and others. This approach is illustrated by two studies in which participants described self and others in a variety of significant roles and relationships by choosing from a list of attachment-related descriptive terms. A hierarchical clustering algorithm, HICLAS (DeBoeck & Rosenberg, 1988), is used to generate a unique graphical representation for each individual's responses. We illustrate the use of HICLAS to (a) assess nomothetic properties of the structures and relate those properties to other variables such as attachment style, and (b) link aspects of any individual's structure with other idiographic data such as interview narratives. Data from HICLAS enhances the interpretation of other, more qualitative idiographic information, and helps to produce new constructs, variables, and propositions amenable to rigorous hypothesis tests in future research. [source]

Approximation of magnetic behavior of complex nanomagnetic materials, using the "P " curves for structural characterization of magnetic suspensions

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2008
N. C. Popa
Abstract The "P " curves for the structural characterization of magnetic nanoparticles suspensions (complex fluids, complex powders, complex composite materials, or living biological materials having magnetic properties) are the graphical representation of the first derivative (relative to the magnetic field strength H) of the magnetization curve relative to its saturation magnetization. In the case of the above materials, the magnetic properties are conferred to various carrier liquids by artificially integrating in their structure ferromagnetic particles of different sizes. The magnetic properties are usually shown by the hysteresis curve. The structure can be seen by (electronic) micrography. The P curves offer another possibility to determine the structure of the magnetic component of a complex fluid by numerical analysis of the magnetization curve experimentally obtained. Starting from these P curves, the paper presents the possibility to approximate the magnetic behavior of these complex nanomagnetic materials. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Crystallographic model quality at a glance

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2009
Ludmila Urzhumtseva
A crystallographic macromolecular model is typically characterized by a list of quality criteria, such as R factors, deviations from ideal stereochemistry and average B factors, which are usually provided as tables in publications or in structural databases. In order to facilitate a quick model-quality evaluation, a graphical representation is proposed. Each key parameter such as R factor or bond-length deviation from `ideal values' is shown graphically as a point on a `ruler'. These rulers are plotted as a set of lines with the same origin, forming a hub and spokes. Different parts of the rulers are coloured differently to reflect the frequency (red for a low frequency, blue for a high frequency) with which the corresponding values are observed in a reference set of structures determined previously. The points for a given model marked on these lines are connected to form a polygon. A polygon that is strongly compressed or dilated along some axes reveals unusually low or high values of the corresponding characteristics. Polygon vertices in `red zones' indicate parameters which lie outside typical values. [source]

A Screen Space Quality Method for Data Abstraction

Graphical disclosures by charities: clarification or distortion?

INTERNATIONAL JOURNAL OF NONPROFIT & VOLUNTARY SECTOR MARKETING, Issue 3 2009
The case of the Netherlands
The literature on graph use and graphical distortions in nonprofit organisations is reviewed, highlighting measurement issues. A sample of 50 disclosed annual reports of Dutch charities containing graphs is analysed, leading to the observation of significant graphical distortions. These distortions seem to be related to organisational efficiency, though not in the way one might expect: better performing charities ,embellish' the data in their graphical representations, whereas the opposite seems to be the case for the less performing charities. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Approximate urban area call drop-out probability estimation in mobile multi-satellite systems

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 2 2003
F. Perez-Fontan
Land mobile satellite (LMS) systems require constellations of multiple satellites to compensate for the large blockage probabilities suffered in urban areas. An approximate methodology based on the street masking function (MKF) or mask concept is presented for the evaluation of system availability. MKFs are graphical representations of the angles (azimuths and elevations) for which a satellite is visible from the terminal's location in the street. MKFs can also be used in the evaluation of second order statistics such as durations of fades or connections. In this paper, the applicability of the mask concept is demonstrated by performing a study of the probability of successful call completion in a LEO-based satellite telephony service. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Who benefits from learning with 3D models? the case of spatial ability

JOURNAL OF COMPUTER ASSISTED LEARNING, Issue 6 2006
T. Huk
Abstract Empirical studies that focus on the impact of three-dimensional (3D) visualizations on learning are to date rare and inconsistent. According to the ability-as-enhancer hypothesis, high spatial ability learners should benefit particularly as they have enough cognitive capacity left for mental model construction. In contrast, the ability-as-compensator hypothesis proposes that low spatial ability learners should gain particular benefit from explicit graphical representations as they have difficulty mentally constructing their own visualizations. This study examines the impact that interactive 3D models implemented within a hypermedia-learning environment have on understanding of cell biology. Test scores in a subsequent knowledge acquisition test demonstrated a significant interaction term between students' spatial ability and presence/absence of 3D models. Only students with high spatial ability benefited from the presence of 3D models, while low spatial ability students got fewer points when learning this way. When using 3D models, high spatial ability students perceived their cognitive load to be low whereas the opposite was true for low spatial ability students. The data suggest that students with low spatial ability became cognitively overloaded by the presence of 3D models, while high spatial ability students benefited from them as their total cognitive load remained within working memory limits. [source]

What does the male function hypothesis claim?

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2000
Burd
Paternal, rather than maternal, fitness consequences of reproductive traits are the lynchpin in many hypotheses about reproductive evolution in hermaphroditic angiosperms. These hypotheses often differ in their predictions, so that supporting or contradictory evidence for one hypothesis may not reflect similarly on another, even though both may be referred to as ,the male function hypothesis'. We provide graphical representations of four male function hypotheses from the recent literature in order to highlight their differences. We offer and explain two recommendations to reduce ambiguity in terminology: (1) male function hypotheses should address the evolution of excess flowers per se, rather than total flower number, which is usually highly plastic in modular organisms with open growth form; and (2) attention must be given to whole plant fitness, rather than fitness per flower or per inflorescence. In empirical studies, we recommend the use of path analysis to dissect the multiple pathways (through both male and female function) by which selection may act on excess flower number. [source]

Resolving Paternity Relationships Using X-Chromosome STRs and Bayesian Networks

JOURNAL OF FORENSIC SCIENCES, Issue 4 2007
Didier Hatsch Ph.D.
Abstract:, X-chromosomal short tandem repeats (X-STRs) are very useful in complex paternity cases because they are inherited by male and female offspring in different ways. They complement autosomal STRs (as-STRs) allowing higher paternity probabilities to be attained. These probabilities are expressed in a likelihood ratio (LR). The formulae needed to calculate LR depend on the genotype combinations of suspected pedigrees. LR can also be obtained by the use of Bayesian networks (BNs). These are graphical representations of real situations that can be used to easily calculate complex probabilities. In the present work, two BNs are presented, which are designed to derive LRs for half-sisters/half-sisters and mother/daughter/paternal grandmother relationships. These networks were validated against known formulae and show themselves to be useful in other suspect pedigree situations than those for which they were developed. The BNs were applied in two paternity cases. The application of the mother/daughter/paternal grandmother BN highlighted the complementary value of X-STRs to as-STRs. The same case evaluated without the mother underlined that missing information tends to be conservative if the alleged father is the biological father and otherwise nonconservative. The half-sisters case shows a limitation of statistical interpretations in regard to high allelic frequencies. [source]

UK Fixed Rate Repayment Mortgage and Mortgage Indemnity Valuation

REAL ESTATE ECONOMICS, Issue 2 2002
José A. Azevedo-Pereira
We use a mean-reverting interest rate model and a lognormal house price diffusion model to evaluate British fixed rate repayment mortgage contracts with (embedded) default and prepayment options. The model also provides values for capped mortgage indemnity guarantees and the corresponding (residual) lender's coinsurance. Since the partial differential equation incorporating the general features of these mortgage contracts does not have a closed-form solution, an explicit finite difference method is used for the valuation (and sensitivity) results, with solution improvements to deal with error bounds. Then we provide graphical representations of each mortgage component as a function of house prices and interest rate levels, along with interpretations of the analysis. We calculate precisely the lender's (residual) exposure to house price risk, given the borrower's options, house and interest rate uncertainty, and customary mortgage indemnity insurance for high loan/collateral ratio mortgages. [source]

Improving calibration without training: the role of task information

APPLIED COGNITIVE PSYCHOLOGY, Issue 4 2003
Tim Rakow
Medical students estimated probabilities that medical school applicants selected randomly from a defined population would be offered a place on the basis of information about eight characteristics of each one. Estimates were biased in favour of acceptance and this was unaffected by mere provision of base rate information. However, a first experiment showed that provision of this information reduced miscalibration after each candidate had been discussed within small groups of participants. A second experiment showed beneficial effects of providing people with the range of probability responses derived from a statistical model of how candidates' characteristics influenced whether or not they were offered a place. Numerical and graphical representations of this information both improved calibration but did so by having different effects on the distribution of participants' probability responses. Copyright © 2003 John Wiley & Sons, Ltd. [source]

High-dimensional data analysis: Selection of variables, data compression and graphics , Application to gene expression

BIOMETRICAL JOURNAL, Issue 2 2009
Jürgen Läuter
Abstract The paper presents effective and mathematically exact procedures for selection of variables which are applicable in cases with a very high dimension as, for example, in gene expression analysis. Choosing sets of variables is an important method to increase the power of the statistical conclusions and to facilitate the biological interpretation. For the construction of sets, each single variable is considered as the centre of potential sets of variables. Testing for significance is carried out by means of the Westfall-Young principle based on resampling or by the parametric method of spherical tests. The particular requirements for statistical stability are taken into account; each kind of overfitting is avoided. Thus, high power is attained and the familywise type I error can be kept in spite of the large dimension. To obtain graphical representations by heat maps and curves, a specific data compression technique is applied. Gene expression data from B-cell lymphoma patients serve for the demonstration of the procedures. [source]

3-Fluoro-2,4-dioxa-3-phosphadecalins as Inhibitors of Acetylcholinesterase.

CHEMISTRY & BIODIVERSITY, Issue 3 2009
A Reappraisal of Kinetic Mechanisms, Diagnostic Methods
Abstract A systematic survey of the acetylcholine-mimetic 2,4-dioxa-3-phosphadecalins as irreversible inhibitors of acetylcholinesterase revealed hitherto overlooked properties as far as the kinetic mechanisms of interaction are concerned. As a support to past and future work in this field, we describe the kinetics of eight reaction schemes that may be found in irreversible enzyme modification and compare them with two mechanism of reversible, slow-binding inhibition. The relevant kinetic equations and their associated graphical representations are given for all mechanisms, and concrete examples illustrate their practical use. Since irreversible inhibition is a time-dependent phenomenon, kinetic analysis is greatly facilitated by fitting the appropriate integrated rate equations to reaction-progress curves by nonlinear regression. This primary scrutiny provides kinetic parameters that are indispensable tools for diagnosing the kinetic mechanism and for calculating inhibition constants. Numerical integration of sets of differential equations is an additional useful investigation tool in critical situations, e.g., when inhibitors are unstable and/or act as irreversible modifiers only temporarily. [source]