Data Analysis

Recent information about statistical analysis, mathematical modeling, behavioral analysis and others.

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Wednesday, December 17, 2008

Graphical Models: New Mathematical Tool Could Unpick Complex Cancer Causes And Help Sociologists Mine Facebook

Researchers at the University of Warwick’s Department of Statistics and Centre for Complexity Science have devised a new research tool that could help unpick the complex cell interactions that lead to cancer and also allow social scientists to mine social networking sites such as Facebook for useful insights.

An approach called “graphical models” can be used by researchers to gain an understanding of a range of systems with multiple interacting factors. These models use mathematical objects called graphs to describe and depict the probability of relationships between each of the components. When used to study molecular biology researchers may be interested in saying something about which molecules influence one another; in the social sciences researchers would use them to understand the relationships between various economic and demographic factors.

However gaining such information from a graphical model can be a very challenging exercise, because of the vast range of possible graphs needed for even a relatively small number of variables. For instance the relatively small network studied by the University of Warwick led team for this research paper had just 14 proteins which were implicated in the development of a form of cancer, but those 14 proteins had a vast number of combinations of possible mutual interactions.

Such tasks would be made much easier if the mathematical tools used to undertake the analysis could somehow embody all the current knowledge of what was likely, and or probable, in the networks they were analysing. Such a mathematical method could be viewed as mimicking how human researchers learn from data, in effect interpreting new information in light of what is already known.

The Warwick researchers led by Dr Sach Mukherjee of Warwick’s Department of Statistics and Centre for Complexity Science have devised just such a method that embeds current knowledge in the mathematical analysis to cut through the vast complexity of this type of analysis using a mechanism called “Informative Priors”.

The researchers took the 14 protein network and created a mathematical tool that was able to incorporate all of what the interactions, and limits on interactions, that were likely and/or probable in such a network of these particular proteins. This allowed a rapid and accurate analysis of the probabilities of interactions between each on the 14 proteins. The technique even able to cope with misconceptions in current understanding of particular networks as it the was designed to “overturn” any reject any data included in the “Informative Priors” that was consistently at odds with any observed new data.

Analysis with these network models was much better able to resolve complex interactions than simple, correlation-based methods. Moreover using informative priors, gave much more accurate results than analysis that incorporated no prior understanding of the network (so called “flat priors”).

The researchers will now use their new technique to examine the network of proteins behind the development of breast cancer but they are also looking at how the tool could be used in social science to mine a vast amount of useful anonymised data from social networking sites such as Facebook to gain significant new understandings of large scale interactions and relationships in society at large.

Source: materials provided by University of Warwick.

Development of a mathematical model for predicting electrically elicited quadriceps femoris muscle forces during isovelocity knee joint motion

Direct electrical activation of skeletal muscles of patients with upper motor neuron lesions can restore functional movements, such as standing or walking. Because responses to electrical stimulation are highly nonlinear and time varying, accurate control of muscles to produce functional movements is very difficult.

Accurate and predictive mathematical models can facilitate the design of stimulation patterns and control strategies that will produce the desired force and motion. In the present study, we build upon our previous isometric model to capture the effects of constant angular velocity on the forces produced during electrically elicited concentric contractions of healthy human quadriceps femoris muscle.

Modeling the isovelocity condition is important because it will enable us to understand how our model behaves under the relatively simple condition of constant velocity and will enable us to better understand the interactions of muscle length, limb velocity, and stimulation pattern on the force producedby the muscle.

Methods: An additional term was introduced into our previous isometric model to predict the force responses during constant velocity limb motion. Ten healthy subjects were recruited for the study.

Using a KinCom dynamometer, isometric and isovelocity force data were collected from the human quadriceps femoris muscle in response to a wide range of stimulation frequencies and patterns. % error, linear regression trend lines, and paired t-tests were used to test how well the model predicted the experimental forces.

In addition, sensitivity analysis was performed using Fourier Amplitude Sensitivity Test to obtain a measure of the sensitivity of our model's output to changes in model parameters.

Results: Percentage RMS errors between modeled and experimental forces determined for each subject at each stimulation pattern and velocity showed that the errors were in general less than 20%. The coefficients of determination between the measured and predicted forces show that the model accounted for ~86% and ~85% of the variances in the measured force-time integrals and peak forces, respectively.

Conclusion: The range of predictive abilities of the isovelocity model in response to changes in muscle length, velocity, and stimulation frequency for each individual make it ideal for dynamic applications like FES cycling.

Author: Ramu Perumal, Anthony S Wexler and Stuart A Binder-Macleod
Credits/Source: Journal of NeuroEngineering and Rehabilitation 2008, 5:33

Monday, July 7, 2008

2DB: a Proteomics database for storage, analysis, presentation, and retrieval of information from mass spectrometric experiments

The amount of information stemming from proteomics experiments involving (multi dimensional) separation techniques, mass spectrometric analysis, and computational analysis is ever-increasing. Data from such an experimental workflow needs to be captured, related and analyzed.

Biological experiments within this scope produce heterogenic data ranging from pictures of one or two-dimensional protein maps and spectra recorded by tandem mass spectrometry to text-based identifications made by algorithms which analyze these spectra. Additionally, peptide and corresponding protein information needs to be displayed.

Results: In order to handle the large amount of data from computational processing of mass spectrometric experiments, automatic import scripts are available and the necessity for manual input to the database has been minimized. Information is in a generic format which abstracts from specific software tools typically used in such an experimental workflow.

The software is therefore capable of storing and cross analysing results from many algorithms. A novel feature and a focus of this database is to facilitate protein identification by using peptides identified from mass spectrometry and link this information directly to respective protein maps.

Additionally, our application employs spectral counting for quantitative presentation of the data. All information can be linked to hot spots on images to place the results into an experimental context.

A summary of identified proteins, containing all relevant information per hot spot, is automatically generated, usually upon either a change in the underlying protein models or due to newly imported identifications. The supporting information for this report can be accessed in multiple ways using the user interface provided by the application.

Conclusions: We present a proteomics database which aims to greatly reduce evaluation time of results from mass spectrometric experiments and enhance result quality by allowing consistent data handling.

Import functionality, automatic protein detection, and summary creation act together to facilitate data analysis. In addition, supporting information for these findings is readily accessible via the graphical user interface provided.

The database schema and the implementation, which can easily be installed on virtually any server, can be downloaded in the form of a compressed file from our project webpage.

Author: Jens Allmer, Sebastian Kuhlgert and Michael Hippler
Credits/Source: BMC Bioinformatics 2008, 9:302

Thursday, June 26, 2008

Systems Properties Of Insulin Signaling Revealed

A team of Swedish researchers has characterized the properties of new signalling systems human insulin in fat cells. Their mathematical modelling provides a better understanding of energy level maintenance (through the hormone insulin) within our bodies.

Entravé function of insulin is the cardinal cause of type 2 diabetes, which currently affects nearly 250 million people worldwide. The disease causes a metabolic malfunction due to incorrect information transfer of insulin concentration in the blood inside the cells of liquid (the cytosol). This transfer of information is through a complex network of protein-protein interactions. The skeleton of the network was characterized, but the systems details, including the relative importance and the time scales of interactions, were hitherto unknown.

Because of the complexity of the network, it has proved difficult to reach such an understanding through simple systems experimental techniques and reasoning. Hence, the team collected experimentally time series data on human fat cells in vitro and evaluated various explanations by translating mechanistic explanations corresponding mathematical models.

In this study, modeling indicated that the recycling of receptors or between the membrane and the cytosol, or reactions of proteins activated lowest in the network are involved in the transfer of information during the first minutes after insulin stimulation.

As more detailed data are available, the authors predict that mathematical modelling will become an increasingly important tool for data analysis, and to promote understanding of insulin and cellular signalling.


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Journal reference:

Citation: Cedersund G, J Roll, Ulfhielm E, Danielsson A, Tidefelt H, et al. Model-Based Testing Assumption of the main mechanisms in the initial phase of Insulin Signaling. Comput Biol, 4 (6): e1000096. DOI: 10.1371/journal.pcbi.1000096
Adapted from material supplied by the Public Library of Science, via EurekAlert! A service of AAAS.

Literature-aided meta-analysis of microarray data: a compendium study on muscle development and disease

Comparative analysis of microarray expression studies is difficult because of the great influence of technical factors on the experimental results. Yet, highlighted differentially expressed genes May allusion to the same biological processes.

However, Conservative manually transfer of genes to biological processes, as pursued by the Gene Ontology (GO) consortium, is incomplete and limited. We automatic assumption that the association of genes with biological processes through thesaurus-controlled mining Medline summaries would be more effective.

Hence, we developed a novel algorithm (LAMA: Literature-Aided meta-analysis) to quantify the similarity between transcriptomics studies. We evaluated our algorithm on a large collection of 102 microarray studies published in muscle development and disease and compared the similarity measures based on gene duplication and over-representation of biological processes assigned by GO.

Results: Although the overlap in the two genes and over-GO-which was poor, LAMA found much more biologically significant links between studies, with much weaker influence of technical factors. LAMA properly grouped muscular dystrophy, regeneration and myositis studies, and linked patient and studies mouse model.

LAMA also gets the connection of biological concepts. Among other new discoveries, we Cullin proteins associated ubiquitinylation a class of proteins, genes with a regulated during muscle regeneration, while ubiquitinylation has already been reported to be undertaken during the reverse process: muscular atrophy.

Conclusion: Our literature based on an analysis of association is able to find hidden biological common denominators in microarray studies, and circumvent the need for raw data analysis or Conservative genes annotation of databases.



Author: Rob Jelier, Peter AC 't Hoen, Ellen Sterrenburg, Johan T. den Dunnen, Gert-Jan van Ommen B., Jan A. Kors and Barend Mons
Credits / Source: BMC Bioinformatics 2008, 9:291

Friday, May 23, 2008

Big Ten Network Turns to STATS for Enhanced Broadcast Support and Web Site Content

CHICAGO & NORTHBROOK, Ill. STATS LLC, the world’s leading sports information provider, and the Big Ten Network announced today the completion of a long-term agreement to incorporate STATS’ content, research and production resources into the Big Ten Network’s broadcasts and web site. The partnership began with the launch of the Big Ten Network in August 2007.

“Today’s sports culture is built around fans being able to receive information that can give perspective and analysis before, during and after the game. STATS is the industry leader in sports statistics and has a proven track record in providing the type of relevant and timely data that our viewers want,” said Leon Schweir, Big Ten Network Executive Producer and Vice President for Production.

“We’re very proud to have been a part of the Big Ten Network’s successful debut season. The Big Ten Network is setting a new standard in collegiate programming and we believe STATS’ data, content and analysis will be a strong part of their product for years to come,” said Steve Byrd, STATS’ Executive Vice President.

The Big Ten Network’s web site, www.bigtennetwork.com, utilizes STATS’ in-depth collegiate content including player and team stats, leader boards, in-progress play-by-play and scores. In addition, STATS provides Associated Press news, headlines and photos.

STATS is also the Big Ten Network’s exclusive statistical provider for its game telecasts and studio shows. STATS’ comprehensive broadcast support includes both traditional pre-game statistical packages for graphics as well as real-time score updates from around the country. Big Ten Network will also utilize STATS’ industry renowned web-based statistics tool, STATS Pass®, along with its celebrated game notes and immediate access to its expert research staff.

About Big Ten Network

The Big Ten Network is dedicated to covering the Big Ten Conference and its 11 member institutions. The Big Ten Network provides unprecedented access to an extensive schedule of conference sports events and shows; original programs in academics, the arts and sciences; campus activities; and associated personalities. Sports programming includes live coverage of more major men’s and women’s events than ever before, along with news, highlights and analysis, all complemented by hours of university-produced campus programming. The network is available to all cable and satellite carriers and television distributors nationwide, with most programs offered in stunning high-definition television (HDTV). The Big Ten Network is a joint venture between subsidiaries of the Big Ten Conference and Fox Cable Networks. For more information regarding the Big Ten Network, visit www.BigTenNetwork.com.

About STATS LLC

With more than 25 years of experience in sophisticated sports data collection, processing and distribution, STATS is the world's leading sports information, content and statistical analysis company. STATS offers a worldwide portfolio of sports information solutions, including the company’s hallmark of real-time scores, historical sports information and turnkey fantasy sports operation, along with AP editorial content, breaking sports news and photos. STATS’ innovative sports information solutions are utilized in numerous business segments: professional teams; sports broadcast production, cable and satellite networks; interactive television; broadband, wireless and internet; game developers and fantasy sports providers; print media and wire services. STATS is owned jointly by the Associated Press and News Corporation, with corporate offices in Bangalore, Barcelona, Beijing, Chicago, Hong Kong, London, Los Angeles, Mexico City, Milan, Mumbai, Münster, New York, The Hague and Tokyo. www.stats.com

Contacts

Big Ten Network
Mike Vest
312-665-0737
mike.vest@bigtennetwork.com
or
STATS LLC
Nick Stamm
847-583-2110
stamm@stats.com

Mathematical modeling and analysis of insulin clearance in vivo

Analyzing the dynamics of insulin concentration in the blood is necessary for a comprehensive understanding of the effects of insulin in vivo. Insulin removal from the blood has been addressed in many studies.

The results are highly variable with respect to insulin clearance and the relative contributions of hepatic and renal insulin degradation.

Results: We present a dynamic mathematical model of insulin concentration in the blood and of insulin receptor activation in hepatocytes. The model describes renal and hepatic insulin degradation, pancreatic insulin secretion and nonspecific insulin binding in the liver.

Hepatic insulin receptor activation by insulin binding, receptor internalization and autophosphorylation is explicitly included in the model. We present a detailed mathematical analysis of insulin degradation and insulin clearance.

Stationary model analysis shows that degradation rates, relative contributions of the different tissues to total insulin degradation and insulin clearance highly depend on the insulin concentration.

Conclusions: This study provides a detailed dynamic model of insulin concentration in the blood and of insulin receptor activation in hepatocytes.

Experimental data sets from literature are used for the model validation. We show that essential dynamic and stationary characteristics of insulin degradation are nonlinear and depend on the actual insulin concentration.
Author: Markus Koschorreck and Ernst Dieter Gilles
Credits/Source: BMC Systems Biology 2008, 2:43

Published on: 2008-05-13

Source: 7thSpace.

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