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Selected AbstractsAn Empirical Study of Equivalence Judgments vs.DECISION SCIENCES, Issue 2 2001Ratio Judgments in Decision Analysis Abstract Two commonly used elicitation modes on strength of preference, equivalence and ratio judgments, were compared in an experiment. The result from the experiment showed that ratio judgments were less effective than equivalence judgments. Based on an iterative design for eliciting multiattribute preference structures, equivalence judgments outperformed ratio judgments in estimating single-attribute measurable value functions, while being nearly more effective than ratio judgments in assessing multiattribute preference structures. The implications of the results from the experiment are that multiattribute decision-making techniques should take advantage of the decision maker's inclination of making effective equivalence trade-off judgments, and that useful techniques should be devised to incorporate different commonly used techniques, such as multiattribute utility theory and the Analytic Hierarchy Process, to elicit and consolidate equivalence trade-off judgments. [source] Approaches to measuring the effects of wake-promoting drugs: a focus on cognitive functionHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 5 2009Christopher J. Edgar Abstract Objectives In clinical drug development, wakefulness and wake-promotion may be assessed by a large number of scales and questionnaires. Objective assessment of wakefulness is most commonly made using sleep latency/maintenance of wakefulness tests, polysomnography and/or behavioral measures. The purpose of the present review is to highlight the degree of overlap in the assessment of wakefulness and cognition, with consideration of assessment techniques and the underlying neurobiology of both concepts. Design Reviews of four key areas were conducted: commonly used techniques in the assessment of wakefulness; neurobiology of sleep/wake and cognition; targets of wake promoting and/or cognition enhancing drugs; and ongoing clinical trials investigating wake promoting effects. Results There is clear overlap between the assessment of wakefulness and cognition. There are common techniques which may be used to assess both concepts; aspects of the neurobiology of both concepts may be closely related; and wake-promoting drugs may have nootropic properties (and vice versa). Clinical trials of wake-promoting drugs often, though not routinely, assess aspects of cognition. Conclusions Routine and broad assessment of cognition in the development of wake-promoting drugs may reveal important nootropic effects, which are not secondary to alertness/wakefulness, whilst existing cognitive enhancers may have underexplored or unknown wake promoting properties. Copyright © 2009 John Wiley & Sons, Ltd. [source] A comparison of techniques for hydrograph recession analysisHYDROLOGICAL PROCESSES, Issue 3 2004Joko Sujono Abstract A comparison between commonly used techniques for hydrograph recession analysis, namely the semi-logarithmic plot of a single recession segment, the master recession and a relatively new approach based on wavelet transform was carried out. These methods were applied to a number of flood hydrograph events of two catchments in West Java, Indonesia. The results show that all the methods tested produce reasonable and comparable results. However, problems arise in the semi-logarithmic plot and the master recession, i.e. determining the recession parameter K is not an easy task especially where the plotted data on a semi-logarithmic plot is not a linear but a curved line. On a curved line, the end of direct flow or starting point of baseflow is not clear and it is quite difficult to identify. Hence, the best line as a basis for computing the recession parameter K becomes uncertain. The wavelet transform approach, however, produces promising results and minimizes a number of problems associated with hydrograph recession analysis. The end of direct flow and the location of the baseflow component are easily determined through the wavelet maps. Copyright © 2004 John Wiley & Sons, Ltd. [source] Tunnel stability analysis during construction using a neuro-fuzzy systemINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 15 2005José Luis Rangel Abstract This paper presents an alternative strategy to evaluate the stability of tunnels during the design and construction stages based on a hybrid system, composed by neural, neuro-fuzzy and analytical solutions. A prototype of this system is designed using a database formed by 261 cases, 45 real and the rest synthetic. This system is capable of reproducing the displacements induced at the periphery of the tunnel before and after support installation. The stability of the excavation process is evaluated using a criterion that considers dimensionless parameters based on the shear strength of the media, the induced deformation level in the ground, the plastic radii and the advance of excavation without support. The efficiency and validity of the prototype is verified with two examples of actual tunnels, one included in the database used to train the system and the other not included. The results of both examples show a better approximation than other commonly used techniques. Copyright © 2005 John Wiley & Sons, Ltd. [source] Implementation of quality control methods (physico-chemical, microbiological and sensory) in conjunction with multivariate analysis towards fish authenticityINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 3 2005Ioannis S. Arvanitoyannis Summary Nowadays authenticity of foods and fish in particular has become of crucial importance because of high number of adulteration cases. Authenticity control has gained ground thanks to the development of several rapid physico-chemical and microbiological methods aiming at distinguishing one species from another based on solid scientific evidence. It has been proven that despite the precision and accuracy of robust analytical and protein and DNA-based techniques, detection of authenticity could not be claimed without resorting to multivariate analysis. This review summarizes both the most advanced and state of the art used techniques for detecting fish and seafood authenticity (both in terms of species and geographical origin). Another issue reported in this review is the preservation of fish and seafood through the implementation of old and novel techniques (ice, modified atmosphere packaging). Several informative tables were included in this paper referring to the employed quality control and sensory analysis methods and multivariate analysis for fish and seafood. [source] Extrapolation methods for improving convergence of spherical Bessel integrals for the two-center Coulomb integralsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 11 2006Hassan Safouhi Abstract Multi-center two-electron Coulomb integrals over Slater-type functions are required for any accurate molecular electronic structure calculations. These integrals, which are numerous, are to be evaluated rapidly and accurately. Slater-type functions are expressed in terms of the so-called B functions, which are best suited to apply the Fourier transform method. The Fourier transform method allowed analytic expressions for these integrals to be developed. Unfortunately, the analytic expressions obtained turned out to be extremely difficult to evaluate accurately due to the presence of highly oscillatory spherical Bessel integrals. In this work, we used techniques based on nonlinear transformation and extrapolation methods for improving convergence of these oscillatory spherical Bessel integrals. These techniques, which led to highly efficient and rapid algorithms for the numerical evaluation of three- and four-center two-electron Coulomb and exchange integrals, are now shown to be applicable to the two-center two-electron Coulomb integrals. The numerical results obtained for the molecular integrals under consideration illustrate the efficiency of the algorithm described in the present work compared with algorithms using the epsilon (,) algorithm of Wynn and Levin's u transform. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] Assessment of endothelial function as a marker of cardiovascular risk in patients with rheumatoid arthritisINTERNATIONAL JOURNAL OF RHEUMATIC DISEASES, Issue 3 2010Faisel KHAN Abstract The endothelium is a major regulator of cardiovascular function and maintains an atheroprotective role through several mechanisms, including vasodilatation, inhibition of platelet aggregation, having anticoagulant and profibrinolytic effects, and having an anti-inflammatory effect. Early changes in the normal functioning of the endothelium are key initiating factors in the development and progression of atherosclerosis. These changes are present well before the presentation of clinical symptoms. Thus, researchers have focused much attention on developing methods for reliable non-invasive testing of endothelial function to allow early detection and monitoring and progression of subclinical atherosclerosis. To date, there is a wide range of methods in use to assess endothelial function, each with its own advantages and limitations. Ideally, the tests should be non-invasive to allow repeated measurements and be applicable in normal healthy subjects and also in children. Given the wide range of regulatory functions of the endothelium, it is not surprising that there is no single measure of endothelial function that provides all the necessary information regarding vascular integrity in different vascular beds. Therefore, a combination of tests examining different components of the vascular system is more appropriate. Since patients with rheumatoid arthritis have increased mortality due to cardiovascular disease, assessment of endothelial function could prove to be useful tools in the identification and monitoring of cardiovascular risk. The purpose of this review is to give a brief overview of some of the commonly used techniques for assessment of endothelial function, and in particular on those that have been used in studies of patients with rheumatoid arthritis. [source] Determination of directionally dependent structural and microstructural information using high-energy X-ray diffractionJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 6 2008J. E. Daniels High-energy synchrotron X-ray diffraction using a monochromatic beam and large area detector offers a unique method for the study of directionally dependent sample information. The very short wavelengths and subsequent low scattering angles mean that scattering vectors at all angles approximately perpendicular to the beam direction are sampled simultaneously. Here a method is proposed and demonstrated in which the magnitude and directions of structural and microstructural changes can be determined with higher resolution than was possible with previously used techniques. The method takes advantage of parametric refinements over multiple data sets using the profile fitting package TOPAS. Examples of the technique applied to the study of strains in multiphase zirconium alloys and microstructural texture in ferroelastic/ferroelectric ceramics are given. The angular precision in lattice strain for a diffraction image with good statistics is found to be below 0.1°. [source] The influence of management regime and altitude on the population structure of Succisapratensis: implications for vegetation monitoringJOURNAL OF APPLIED ECOLOGY, Issue 4 2001Christoph Bühler Summary 1,Environmental change and land use may alter the vegetation typical of wetland habitats. However, commonly used techniques for vegetation monitoring that are based on species composition are often not suitable to detect gradual changes in the structure of vegetation at an early stage. In this study we tested if this methodical deficiency could be overcome by observation of the stage structure of a perennial target species. 2,We studied the density and frequency distribution of four phenological stages of the perennial plant Succisapratensis in 24 calcareous fens in eastern Switzerland. These fens differed in management type (mowing, cattle-grazing) and altitude (low, medium, high). Among grazed fens, the intensity of management was quantified by direct observation. Species composition and canopy structure of the plant community surrounding S. pratensis were also measured. 3,High altitude had a positive effect on the density of adult plants of S. pratensis only in mown fens, whereas in grazed fens adult density was highest at medium altitude. 4,Local densities of seedlings and vegetative adults within a fen were higher in mown than in grazed fens, and lower in fens of the lowest altitude level than of the two higher ones. However, there were no differences in the relative proportions of all four phenological stages among main factors except that significantly fewer seedlings occurred in fens of the lowest altitude level. 5,It is the intensity rather than the mere type of management regime that is crucial for shaping populations of S. pratensis: for grazed fens, there is a negative relationship between intensity of grazing and density of adult plants of S. pratensis. Moreover, the number, the relative proportion of seedlings and the seed-set are all negatively correlated with grazing intensity. 6,The species composition of the plant community, but not its physical structure, was significantly related to the relative proportion of seedlings of S. pratensis, which supports the indicator qualities of the target species. 7,Monitoring the population structure of one or several target species provides important indicator information about the stability of a whole plant community. For the target-species approach we propose to use characteristic but frequently and steadily occurring species instead of rare or endangered ones. [source] Ancient mitochondrial DNA analyses of Iberian sturgeonsJOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2009A. Ludwig Summary Today's European sturgeons are relics of erstwhile widely distributed populations, diminished mainly by overfishing and habitat changes over the centuries. While extinct European populations in the Baltic and North seas have been identified as Acipenser oxyrhinchus or A. sturio, a clear species determination on the Iberian Peninsula is still lacking. Plans to conserve existing populations and to re-introduce extinct wild populations in European rivers will benefit from information of historic population/genotype composition. In this study, we used techniques involving ancient DNA as well as morphological comparisons based on bony scutes to identify twelve samples from five archaeological sites (650bc,1500ad, one sample dated 10.1,11.8 ky) on the Iberian Peninsula. All amplified PCR products of bony scutes (n = 5) had the mitochondrial DNA haplotypes of European sturgeon. Neither mitochondrial haplotypes of A. naccarii nor mitochondrial haplotypes of A. oxyrinchus were found. [source] Bronze Age painted plaster in Mycenaean Greece: a pilot study on the testing and application of micro-Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 8-9 2004Ann Brysbaert Abstract Since the first discoveries of Minoan and Mycenaean painted plaster around the end of the 19th and early 20th centuries, iconographic and, to a lesser extent, technological studies have gone hand in hand in order to understand how these prehistoric societies were able to produce some of the earliest and most significant works of art in Bronze Age Europe and the eastern Mediterranean. These paintings claim to be among the first to be executed in the buon fresco technique. Past technological studies employed wet chemical methods, x-ray diffraction (XRD), optical emission spectroscopy and a range of microscopic techniques based on cross-sections of samples in order to investigate these fragmentary paintings. Most of these methods required destructive sampling and this is now, rightly so, very much restricted. Consequently, other non-micro-destructive approaches are being tested at present. Micro-Raman spectroscopy (MRS) has proven more than once its potential for non-destructive analysis of works of art and in archaeology in the recent past. Its application to this early fragmentary material is presented here for the first time. Interesting results were the identification of both organic (indigo) and non-crystalline materials (limonite), which complements the knowledge obtained from traditionally used techniques. Although not without problems (high fluorescence prevented identification of Egyptian Blue), non-destructive MRS yielded results comparable to XRD and provided the first identification of indigo blue on this medium, and can hence be considered very useful in future sample-reducing strategies considering these scarce materials. Copyright © 2004 John Wiley & Sons, Ltd. [source] Use of the wavelet method for analyzing electrochemical noise dataMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 12 2007O. Duran This research paper shows the application of the mathematical tool "wavelet's" to be used in the interpretation and analysis of electrochemical noise signals. The Fast Fourier Transformation (FFT) is one of the most commonly used techniques for analyzing electrochemical noise. But the application of this methodology to the analysis of stochastic signals does not allow their interpretation in a suitable way. The wavelet's methodology carries out the analysis by means of the construction of finite base functions. In several studies, it has been found out that the function that is closest to the electrochemical oscillations is the one called "coiflets," which presents a similar geometry to what it is observed when an ionic,electronic interchange occurs during an electrochemical interphase. The analysis that appears here was implemented using the toolbox "LabViewÔ." [source] Fire-mediated interactions between shrubs in a South American temperate savannahOIKOS, Issue 9 2009Fernando Biganzoli We examined spatial patterns of fire-caused mortality and after-fire establishment of two dominant shrub species, Baccharis dracunculifolia and Eupatorium buniifolium in a humid temperate South American savannah. Our objective was to determine whether fires mediate in interactions between these two species. After a natural fire burned a large tract of savannah, we established two plots (respectively 550 and 500 m2) within which we mapped all surviving and dead shrubs as well as all individuals of shrub species that recruited in the following year. We used techniques of point-pattern analysis to test specific null hypotheses about spatial associations in the distribution, mortality, and establishment of shrubs. Results support the notions that fire mediates interactions between these two species. Fire-caused death of E. buniifolium tended to occur selectively in the vicinities of Baccharis individuals, and recruitment of B. dracunculifolia tended to be concentrated in the places of dead shrubs. These responses, however, were contingent on local abundances of shrubs which depend in part from the recent fire history. Anthropogenic perturbation of the natural fire regime would have therefore distorted the role of fire mediated interactions as drivers of the dynamics of the vegetation of this temperate savannah. [source] A review of charge transport and recombination in polymer/fullerene organic solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 8 2007A. Pivrikas Abstract The charge carrier transport and recombination in two types of thermally treated bulk-heterojunction solar cells is reviewed: in regioregular poly(3-hexylthiophene) (RRP3HT) mixed with 1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-methanofullerene (PCBM) and in the blend of poly[2-methoxy-5-(3,7-dimethyloctyloxy)-phenylene vinylene] (MDMO-PPV) mixed with PCBM. The charge carrier mobility and bimolecular recombination coefficient have been comparatively studied by using various techniques including Time-of-Flight (ToF), Charge Extraction by Linearly Increasing Voltage (CELIV), Double Injection (DI) transients, Current,Voltage (I,V) technique. It was found that the carrier mobility is at least an order of magnitude higher in RRP3HT/PCBM blends compared to MDMO-PPV/PCBM. Moreover, all used techniques demonstrate a heavily reduced charge carrier recombination in RRP3HT/PCBM films compared to Langevin-type carrier bimolecular recombination in MDMO-PPV/PCBM blends. As a result of long carrier lifetimes the formation of high carrier concentration plasma in RRP3HT/PCBM blends is demonstrated and plasma extraction methods were used to directly estimate the charge carrier mobility and bimolecular recombination coefficients simultaneously. A weak dependence of bimolecular recombination coefficient on the applied electric field and temperature demonstrates that carrier recombination is not dominated by charge carrier mobility (Langevin-type recombination) in RRP3HT/PCBM blends. Furthermore, we found from CELIV techniques that electron mobility in RRP3HT/PCBM blends is independent on relaxation time in the experimental time window (approx. hundreds of microseconds to tens of milliseconds). This reduced carrier bimolecular recombination in RRP3HT/PCBM blends implies that the much longer carrier lifetimes can be reached at the same concentrations which finally results in higher photocurrent and larger power conversion efficiency of RRP3HT/PCBM solar cells. Copyright © 2007 John Wiley & Sons, Ltd. [source] The power of cooperative investigation: Summary and comparison of the HUPO Brain Proteome Project pilot study resultsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 18 2006Kai A. Reidegeld Abstract Within the pilot phase of the HUPO Brain Proteome Project, nine participating laboratories analysed human (epilepsy and/or post mortem material) and mouse brain samples (embryonic, juvenile and adult), respectively, using a variety of different state of the art techniques. Thirty-seven different analytical approaches were accomplished. Of these analyses, 17 were done differentially, i.e. the protein expression patterns of the different samples (human or mouse) were compared. A catalogue of all proteins present in the respective sample was built in 20 analyses (mapping). All data were collected in the Data Collection Center in Bochum, Germany, and were reprocessed according to thoroughly defined parameters. In this report, a summary of all results and inter-laboratory comparisons with respect to the number of identified proteins, the analysed organism, and the used techniques is presented. [source] Comparison of two new approaches to variable ordering for binary decision diagramsQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 3 2001L. M. Bartlett Abstract Fault tree analysis, FTA, is one of the most commonly used techniques for safety system analysis. There can be problems with the efficiency and accuracy of the approach when dealing with large tree structures. Recently the binary decision diagram (BDD) methodology has been introduced which significantly aids the analysis of the fault tree diagram. The approach has been shown to improve both the efficiency of determining the minimal cut sets of the fault tree, and also the accuracy of the calculation procedure used to quantify the top event parameters. To utilize the BDD technique the fault tree structure needs to be converted into the BDD format. Converting the fault tree is relatively straightforward but requires the basic events of the tree to be placed in an ordering. The ordering of the basic events is critical to the resulting size of the BDD, and ultimately affects the performance and benefits of this technique. There are a number of variable ordering heuristics in the literature, however the performance of each depends on the tree structure being analysed. These heuristic approaches do not yield a minimal BDD structure for all trees, some approaches generate orderings that are better for some trees but worse for others. Within this paper two approaches to the variable ordering problem have been discussed. The first is the pattern recognition approach of neural networks, which is used to select the best ordering heuristic for a given fault tree from a set of alternatives. The second examines a completely new heuristic approach of using the structural importance of a component to produce a ranked ordering. The merits of each are discussed and the results compared. Copyright © 2001 John Wiley & Sons, Ltd. [source] Sphenopalatine Endoscopic Ganglion Block: A Revision of a Traditional Technique for Cluster HeadacheTHE LARYNGOSCOPE, Issue 8 2006Giovanni Felisati MD The diagnosis of chronic cluster headache (CH), the most painful form of headache, is based on typical clinical features characterized by strictly unilateral pain with no side shift and ipsilateral oculofacial autonomic phenomena. The attacks occur several times a day for periods of 1 to 2 months in the episodic form of the disease or less frequently on a daily basis in the chronic form. The pathogenesis of CH involves the activation of parasympathetic nerve structures located within the sphenopalatine ganglion (SPG), which explains many of the associated symptoms, whereas the activation of the ipsilateral hypothalamic gray matter may explain its typical circadian and circannual periodicity. A number of surgical approaches have been tried in cases of chronic CH resistant to pharmacologic therapy, of which SPG blockade has been shown to have certain efficacy. We have adopted a new technique based on endoscopic ganglion blockade that approaches the pterigo-palatine fossa by way of the lateral nasal wall and consists of the injection of a mixture of local anesthetics and corticosteroids, which was performed in 20 selected patients with chronic CH, according to the International Headache Society criteria (18 male, 2 female; mean age 40 yr), who were selected for SPG blockade because they were totally drug resistant. The symptoms improved significantly, but always only temporarily, in 11 cases. These results should be considered rather good because, unlike other frequently used techniques, SPG blockade is not invasive and should therefore always be attempted before submitting patients to more invasive surgical approaches. [source] Cryopreservation technique: comparison of Test yolk buffer versus SpermCryo and vapour versus computerised freezingANDROLOGIA, Issue 1 2008L. Paras Summary Semen cryopreservation offers the possibility to maintain fertility over a long time period e.g. for male cancer patients. Although its use expands worldwide, there is no established method that can be referred to as an entrenched standard for routine laboratory use. Cryodamage is still a general phenomenon and the success of cryopreservation is affected on one side by the cryoprotective agent and on the other side by the technique of freezing. In this methodological study, we compared the newly offered SpermCryo (SC) with the standard used cryoprotectant Test yolk buffer (TYB). We could show that TYB is superior to SC. In addition, we compared the two mainly used techniques for cryopreservation: computerised slow-stage freezing versus nitrogen vapour fast freezing. Regarding the sperm post-thaw motility and viability, no significant difference was found between these two methods. In conclusion, TYB can be recommended as a cryomedium of first choice and the appropriate freezing technique can be selected according to the local facilities of the institution. [source] Philips QT Interval Measurement Algorithms for Diagnostic, Ambulatory, and Patient Monitoring ECG ApplicationsANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 2009F.A.C.C., Sophia H. Zhou Ph.D. Background: Commonly used techniques for QT measurement that identify T wave end using amplitude thresholds or the tangent method are sensitive to baseline drift and to variations of terminal T wave shape. Such QT measurement techniques commonly underestimate or overestimate the "true" QT interval. Methods: To find the end of the T wave, the new Philips QT interval measurement algorithms use the distance from an ancillary line drawn from the peak of the T wave to a point beyond the expected inflection point at the end of the T wave. We have adapted and optimized modifications of this basic approach for use in three different ECG application areas: resting diagnostic, ambulatory Holter, and in-hospital patient monitoring. The Philips DXL resting diagnostic algorithm uses an alpha-trimming technique and a measure of central tendency to determine the median QT value of eight most reliable leads. In ambulatory Holter ECG analysis, generally only two or three channels are available. QT is measured on a root-mean-square vector magnitude signal. Finally, QT measurement in the real time in-hospital application is among the most challenging areas of QT measurement. The Philips real time QT interval measurement algorithm employs features from both Philips DXL 12-lead and ambulatory Holter QT algorithms with further enhancements. Results: The diagnostic 12-lead algorithm has been tested against the gold standard measurement database established by the CSE group with results surpassing the industrial ECG measurement accuracy standards. Holter and monitoring algorithm performance data on the PhysioNet QT database were shown to be similar to the manual measurements by two cardiologists. Conclusion: The three variations of the QT measurement algorithm we developed are suitable for diagnostic 12-lead, Holter, and patient monitoring applications. [source] A Nonsurgical Technique for Blood Access in Extracorporeal Affinity Adsorption of Antibodies in RatsARTIFICIAL ORGANS, Issue 4 2007Linda Mårtensson Abstract:, Monoclonal antibodies for targeting cytotoxic conjugates to tumor cells are currently being evaluated together with extracorporeal affinity adsorption. The aim of the adsorption was to reduce undesired side effects in normal organs and to increase the tumor-to-normal tissue ratios. This technique is also applicable to several other therapeutic areas such as immune-mediated disorders, that is, autoimmunity, allergy, and transplantation rejection. We describe an improved technique for extracorporeal affinity adsorption of radiolabeled biotinylated antibodies in rats. Blood access is established through the tail artery and tail vein, without surgical insertion of permanent catheters. This technique is simple, does not require surgery, and causes only minimal stress to the animals. In addition, experiments can be carried out on several animals simultaneously. This new technique is of considerable benefit for studying extracorporeal affinity adsorption in rats, as experiments can be carried out with negligible anatomical and physiological interventions, compared to previously used techniques. [source] Bayesian Robust Inference for Differential Gene Expression in Microarrays with Multiple SamplesBIOMETRICS, Issue 1 2006Raphael Gottardo Summary We consider the problem of identifying differentially expressed genes under different conditions using gene expression microarrays. Because of the many steps involved in the experimental process, from hybridization to image analysis, cDNA microarray data often contain outliers. For example, an outlying data value could occur because of scratches or dust on the surface, imperfections in the glass, or imperfections in the array production. We develop a robust Bayesian hierarchical model for testing for differential expression. Errors are modeled explicitly using a t -distribution, which accounts for outliers. The model includes an exchangeable prior for the variances, which allows different variances for the genes but still shrinks extreme empirical variances. Our model can be used for testing for differentially expressed genes among multiple samples, and it can distinguish between the different possible patterns of differential expression when there are three or more samples. Parameter estimation is carried out using a novel version of Markov chain Monte Carlo that is appropriate when the model puts mass on subspaces of the full parameter space. The method is illustrated using two publicly available gene expression data sets. We compare our method to six other baseline and commonly used techniques, namely the t -test, the Bonferroni-adjusted t -test, significance analysis of microarrays (SAM), Efron's empirical Bayes, and EBarrays in both its lognormal,normal and gamma,gamma forms. In an experiment with HIV data, our method performed better than these alternatives, on the basis of between-replicate agreement and disagreement. [source] Advances in the genetics of sarcoidosisCLINICAL GENETICS, Issue 5 2008G Smith Sarcoidosis is an uncommon disease of granulomatous inflammation. Genetic predisposition to sarcoidosis is indicated by observations of familial clustering, increased concordance in monozygotic twins over other siblings, and variations in susceptibility and disease presentation among different ethnic groups. Published studies on sarcoidosis have investigated a variety of genetic associations. These studies used techniques ranging from classic human lymphocyte antigen genotype correlations to genome-wide linkage scans. Results have both supported and refuted disease associations with a number of genes potentially involved in the pathogenesis of sarcoidosis. Here, we review representative studies concerning the genetics of sarcoidosis. While investigations to date have failed to identify a unifying genetic signature associated with sarcoidosis, numerous studies have identified genetic associations with disease subtypes or within specific populations. These studies suggest that genetic susceptibility to sarcoidosis is complex and polygenic in nature. Future studies will help clarify the genetics of sarcoidosis and allow for the development of diagnostic, prognostic and therapeutic technologies. [source] | ||||||||||||||||||||||