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Selected AbstractsAccounting for velocity anisotropy in seismic traveltime tomography: a case study from the investigation of the foundations of a Byzantine monumental buildingGEOPHYSICAL PROSPECTING, Issue 1 2006L. Polymenakos ABSTRACT We estimate velocity anisotropy factors from seismic traveltime tomographic data and apply a correction for anisotropy in the inversion procedure to test possible improvements on the traveltime fit and the quality of the resulting tomographic images. We applied the anisotropy correction on a traveltime data set obtained from the investigation of the foundation structure of a monumental building: a Byzantine church from the 11th century AD, in Athens, Greece. Vertical transverse isotropy is represented by one axis of symmetry and one anisotropy magnitude for the entire tomographic inversion grid. We choose the vertical direction for the symmetry axis by analysing the available data set and taking into account information on the character of the foundations of the church from the literature and past excavations. The anisotropy magnitude is determined by testing a series of values of anisotropy and examining their effect on the tomographic inversion results. The best traveltime fit and image quality are obtained with an anisotropy value (Vmax/Vmin) of 1.6, restricted to the high velocity structures in the subsurface. We believe that this anisotropy value, which is significantly higher than the usual values reported for near-surface geological material, is related to the fabric of the church foundations, due to the shape of the individual stone blocks and the layout of the stonework. Inversion results obtained with the correction for anisotropy indicate that both the traveltime fit and the image quality are improved, providing an enhanced reconstruction of the velocity field, especially for the high-velocity features. Based on this enhanced and more reliable reconstruction of velocity distribution, an improved image of the subsurface material character was made possible. In particular, the pattern and state of the church foundations and possible weak ground material areas were revealed more clearly. This improved subsurface knowledge may assist in a better design of restoration measures for monumental buildings such as Byzantine churches. [source] Crop planting dates: an analysis of global patternsGLOBAL ECOLOGY, Issue 5 2010William J. Sacks ABSTRACT Aim, To assemble a data set of global crop planting and harvesting dates for 19 major crops, explore spatial relationships between planting date and climate for two of them, and compare our analysis with a review of the literature on factors that drive decisions on planting dates. Location, Global. Methods, We digitized and georeferenced existing data on crop planting and harvesting dates from six sources. We then examined relationships between planting dates and temperature, precipitation and potential evapotranspiration using 30-year average climatologies from the Climatic Research Unit, University of East Anglia (CRU CL 2.0). Results, We present global planting date patterns for maize, spring wheat and winter wheat (our full, publicly available data set contains planting and harvesting dates for 19 major crops). Maize planting in the northern mid-latitudes generally occurs in April and May. Daily average air temperatures are usually c. 12,17 °C at the time of maize planting in these regions, although soil moisture often determines planting date more directly than does temperature. Maize planting dates vary more widely in tropical regions. Spring wheat is usually planted at cooler temperatures than maize, between c. 8 and 14 °C in temperate regions. Winter wheat is generally planted in September and October in the northern mid-latitudes. Main conclusions, In temperate regions, spatial patterns of maize and spring wheat planting dates can be predicted reasonably well by assuming a fixed temperature at planting. However, planting dates in lower latitudes and planting dates of winter wheat are more difficult to predict from climate alone. In part this is because planting dates may be chosen to ensure a favourable climate during a critical growth stage, such as flowering, rather than to ensure an optimal climate early in the crop's growth. The lack of predictability is also due to the pervasive influence of technological and socio-economic factors on planting dates. [source] A comprehensive analysis of QTL for abdominal fat and breast muscle weights on chicken chromosome 5 using a multivariate approachANIMAL GENETICS, Issue 2 2009G. Le Mignon Summary Quantitative trait loci (QTL) influencing the weight of abdominal fat (AF) and of breast muscle (BM) were detected on chicken chromosome 5 (GGA5) using two successive F2 crosses between two divergently selected ,Fat' and ,Lean' INRA broiler lines. Based on these results, the aim of the present study was to identify the number, location and effects of these putative QTL by performing multitrait and multi-QTL analyses of the whole available data set. Data concerned 1186 F2 offspring produced by 10 F1 sires and 85 F1 dams. AF and BM traits were measured on F2 animals at slaughter, at 8 (first cross) or 9 (second cross) weeks of age. The F0, F1 and F2 birds were genotyped for 11 microsatellite markers evenly spaced along GGA5. Before QTL detection, phenotypes were adjusted for the fixed effects of sex, F2 design, hatching group within the design, and for body weight as a covariable. Univariate analyses confirmed the QTL segregation for AF and BM on GGA5 in male offspring, but not in female offspring. Analyses of male offspring data using multitrait and linked-QTL models led us to conclude the presence of two QTL on the distal part of GGA5, each controlling one trait. Linked QTL models were applied after correction of phenotypic values for the effects of these distal QTL. Several QTL for AF and BM were then discovered in the central region of GGA5, splitting one large QTL region for AF into several distinct QTL. Neither the ,Fat' nor the ,Lean' line appeared to be fixed for any QTL genotype. These results have important implications for prospective fine mapping studies and for the identification of underlying genes and causal mutations. [source] A semi-Markov model of disease recurrence in insured dogsAPPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 5 2007Xikui Wang Abstract We use a semi-Markov model to analyse the stochastic dynamics of disease occurrence of dogs insured in Canada from 1990 to 1999, and the probability pattern of death from illness. After statistically justifying the use of a stochastic model, we demonstrate that a stationary first-order semi-Markov process is appropriate for analysing the available data set. The probability transition function is estimated and its stationarity is tested statistically. Homogeneity of the semi-Markov model with respect to important covariates (such as geographic location, insurance plan, breed and age) is also statistically examined. We conclude with discussions and implications of our results in veterinary contents. Copyright © 2007 John Wiley & Sons, Ltd. [source] Quantifying the Predictive Performance of Prognostic Models for Censored Survival Data with Time-Dependent CovariatesBIOMETRICS, Issue 2 2008R. Schoop Summary Prognostic models in survival analysis typically aim to describe the association between patient covariates and future outcomes. More recently, efforts have been made to include covariate information that is updated over time. However, there exists as yet no standard approach to assess the predictive accuracy of such updated predictions. In this article, proposals from the literature are discussed and a conditional loss function approach is suggested, illustrated by a publicly available data set. [source] Trauma Center Utilization for Children in California 1998,2004: Trends and Areas for Further AnalysisACADEMIC EMERGENCY MEDICINE, Issue 4 2007N. Ewen Wang MD Abstract Background: While it is known that trauma systems improve the outcome of injury in children, there is a paucity of information regarding trauma system function amid changes in policies and health care financing that affect emergency medical systems for children. Objectives: To describe the trends in the proportion of pediatric trauma patients acutely hospitalized in trauma-designated versus non,trauma-designated hospitals. Methods: This was a retrospective observational study of a population-based cohort obtained by secondary analysis of a publicly available data set: the California Office of Statewide Health Planning and Development Patient Discharge Database from 1998 to 2004. Patients were included in the analysis if they were 0,19 years old, had International Classification of Disease, Ninth Revision (ICD-9) diagnostic codes and E-codes indicative of trauma, had an unscheduled admission, and were discharged from a general acute care hospital (N= 111,566). Proportions of patients hospitalized in trauma-designated hospitals versus non,trauma-designated hospitals were calculated for Injury Severity Score and death. Injury Severity Scores were calculated from ICD-9 codes. Primary outcomes were hospitalization in a trauma center and death two or more days after hospitalization. Results: Over the study period, the proportion of children aged 0,14 years with acute trauma requiring hospitalization and who were cared for in trauma-designated hospitals increased from 55% (95% confidence interval [CI] = 54% to 56%) in 1998 to 66% (95% CI = 65% to 67%) in 2004 (p < 0.01). For children aged 15,19 years, the proportion increased from 55% (95% CI = 54% to 57%) in 1998 to 74% (95% CI = 72% to 75%) in 2004 (p < 0.0001). When trauma discharges were stratified by injury severity, the proportion of children with severe injury who were hospitalized in trauma-designated hospitals increased from 69% (95% CI = 66% to 72%) in 1998 to 84% (95% CI = 82% to 87%) in 2004, a rate higher than in children with moderate injury (59% [95% CI = 58% to 61%] in 1998 and 75% [95% CI = 74% to 76%] in 2004) and mild injury (51% [95% CI = 50% to 52%] in 1998 and 63% [95% CI = 62% to 64%] in 2004) (p < 0.0001 for each injury severity category and both age groups). Of the hospitalized children who died two or more days after injury (n= 502), 18.1% died in non,trauma-designated hospitals (p < 0.002 for children aged 0,14 years; p = 0.346 for children aged 15,19 years). Conclusions: An increasing majority of children with trauma were cared for in trauma-designated hospitals over the study period. However, 23% of children with severe injuries, and 18.1% of pediatric deaths more than two days after injury, were cared for in non,trauma-designated hospitals. These findings demonstrate an important opportunity for improvement. If we can characterize those children who do not access the trauma system despite severe injury or death, we will be able to design clinical protocols and implement policies that ensure access to appropriate regional trauma care for all children in need. [source] Microwave depolarization versus rain attenuation on earth space in MalaysiaINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 6 2008J. S. Mandeep Abstract The wave propagation experiments using Japanese geostationary satellite Superbird-C have been performed at the Universiti Sains Malaysia earth station. A relationship between rain depolarization and attenuation, valid for earth-space path at microwave wavelengths, is presented. Cumulative rain attenuation and cross-polarization discrimination (XPD) statistics are given for the period of 4 years (2002,2005) at 12.255,GHz. XPD varied from 44,dB at 1% to 16,dB at 0.001% of time the abscissa is exceeded. Comparisons were made with available data sets and with five simple XPD models and the results indicate a good performance by the simple isolation model and the CHU model compared with the others. These results serve as checks on the theoretical models needed for predicting communication system performance in geographical regions especially for equatorial climate where measurements are not available. Copyright © 2008 John Wiley & Sons, Ltd. [source] Preservation potential for Late Quaternary river alluviumJOURNAL OF QUATERNARY SCIENCE, Issue 2 2003John Lewin Abstract Valley sequences of Late Quaternary alluvial units reflect alluvial preservation as well as alluvial production factors. Effects of lateral channel migration, incision, aggradation and channel stability on preservation potential are explored and then considered in the light of 14 available data sets: cartographically dated and model data based on lateral channel migration; well-mapped and dated Late Quaternary valley unit surveys; and composite age,frequency plots for dated alluvial units and flood sediments. Despite much expectable variation between sites, and the complex effects of river-activity combinations, a common characteristic of the data sets examined is the significance of preservation factors. Lateral migration tends to eliminate older units as it creates new alluvial deposits, whereas incision may lead to the preferential preservation of older units beyond the incision slot. Aggradational environments are likely to preserve more complete records, although simultaneous lateral migration may eliminate, possibly repeatedly, the upper parts of alluvial units. The common pattern of inset and incised streams within Pleistocene and early Holocene fills or bedrock gives finite extent to later units within narrowing valleys so that development of new valley-floor units is necessarily at the expense of reprocessing earlier ones. Floods associated with both slack water deposits and berms are also responsible for the removal of accessible earlier materials, thus limiting the preserved record of earlier events. In light of these censoring effects of river activities, the sequence of preserved Late Quaternary units within UK sequences is reconsidered. It is concluded that preservation potential factors have led to spatial and temporal bias in the alluvial record, and that both here and elsewhere preservation potential needs to be considered systematically alongside variable sedimentation resulting from allogenic environmental factors when interpreting the alluvial archive. Copyright © 2003 John Wiley & Sons, Ltd. [source] Autoindexing the diffraction patterns from crystals with a pseudotranslationACTA CRYSTALLOGRAPHICA SECTION D, Issue 6 2009Nicholas K. Sauter Rotation photographs can be readily indexed if enough candidate Bragg spots are identified to properly sample the reciprocal lattice. However, while automatic indexing algorithms are widely used for macromolecular data processing, they can produce incorrect results in special situations where a subset of Bragg spots is systematically overlooked. This is a potential outcome in cases where a noncrystallographic translational symmetry operator closely mimics an exact crystallographic translation. In these cases, a visual inspection of the diffraction image will reveal alternating strong and weak reflections. However, reliable detection of the weak-intensity reflections by software requires a systematic search for a diffraction signal targeted at specific reciprocal-space locations calculated a priori by considering all possible pseudotranslations. Care must be exercised to distinguish between true lattice diffraction and spurious signals contributed by neighboring overlapping Bragg spots, non-Bragg diffraction and noise. Such procedures have been implemented within the autoindexing program LABELIT and applied to known cases from publicly available data sets. Routine use of this type of signal search adds only a few seconds to the typical run time for autoindexing. The program can be downloaded from http://cci.lbl.gov/labelit. [source] Tag SNP selection using particle swarm optimizationBIOTECHNOLOGY PROGRESS, Issue 2 2010Li-Yeh Chuang Abstract Single nucleotide polymorphisms (SNPs) are the most abundant form of genetic variations amongst species. With the genome-wide SNP discovery, many genome-wide association studies are likely to identify multiple genetic variants that are associated with complex diseases. However, genotyping all existing SNPs for a large number of samples is still challenging even though SNP arrays have been developed to facilitate the task. Therefore, it is essential to select only informative SNPs representing the original SNP distributions in the genome (tag SNP selection) for genome-wide association studies. These SNPs are usually chosen from haplotypes and called haplotype tag SNPs (htSNPs). Accordingly, the scale and cost of genotyping are expected to be largely reduced. We introduce binary particle swarm optimization (BPSO) with local search capability to improve the prediction accuracy of STAMPA. The proposed method does not rely on block partitioning of the genomic region, and consistently identified tag SNPs with higher prediction accuracy than either STAMPA or SVM/STSA. We compared the prediction accuracy and time complexity of BPSO to STAMPA and an SVM-based (SVM/STSA) method using publicly available data sets. For STAMPA and SVM/STSA, BPSO effective improved prediction accuracy for smaller and larger scale data sets. These results demonstrate that the BPSO method selects tag SNP with higher accuracy no matter the scale of data sets is used. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] | |||||||||||||