A Review of Two Pelvic Osteotomies Used in the Management of Congenital Hip Dislocation

This paper is a literature search of two common pelvic osteotomies used in the treatment/management of congenital hip dislocation. The Chiari and Salter procedures are reviewed along with their use in restoring normal hip joint, congruency, indication for use, and success rates. The Chiari procedure displaces the acetabulum medially and has the best results in children over four years of age or when the acetabulum is too small for the femoral head. A Salter procedure redirects the entire acetabulum and is optimal for subluxations one and one-half years to adult or dislocations one and one-half to six years

Evaluation of wavelength shifters for spectral separation of barium fluoride emissions

Application of the barium fluoride (BaF2) scintillator for characterization of intense radiation fields has been pursued since the fast component was discovered in the early 1980's. Unfortunately, ~ 80% of the scintillator emissions have a slow ~ 600 ns decay time constant. The long decay time hampers the use of BaF2 at high count rates because the slow emissions appear as an afterglow which has an intensity that varies with the interaction rate in the crystal. The temporal separation of BaF2 emissions by spectral separation using wavelength shifting techniques has been explored in this work. Of the wavelength shifting techniques that were examined, the solvent excitation technique showed the greatest potential, but was insufficient by itself to suppress the slow emissions to the desired degree. All the wavelength shifting techniques yield an enhanced ratio of fast to slow photons, but a decreased fast photoelectron yield.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31384/1/0000297.pd

Evaluation of p-terphenyl and 2,2" dimethyl-p-terphenyl as wavelength shifters for barium fluoride

p-Terphenyl (PTP) and 2,2" dimethyl-p-terphenyl (DMT) have been investigated for use as wavelength shifters (WLSs) for barium fluoride (BaF2) scintillation emission. These two organic fluors are attractive due to their high quantum efficiency, fast fluorescence decay time, and emissions above the wavelength cut-off of borosilicate glass. Measurements of these WLSs dissolved in cyclohexane are presented. Coincidence time spectra and fluorescence decay spectra measured with BaF2 as the pump source, are shown. The fluorescence decay time and the ratio of fast to slow intensities were determined from the fluorescence decay spectrum. The increase in signal resulting from using a WLS between the borosilicate end-window photomultiplier tube and the BaF2 crystal is measured. The motivation behind this work is the development of a gamma-ray spectrometer suitable for high count rate applications. We are also investigating the possibility of separating the fast and slow emissions of BaF2 using optical techniques. PTP and DMT both can spectrally separate BaFe2 emissions to a marginal extent.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30880/1/0000545.pd

Algorithms: simultaneous error-correction and rooting for gene tree reconciliation and the gene duplication problem

<p>Abstract</p> <p>Background</p> <p>Evolutionary methods are increasingly challenged by the wealth of fast growing resources of genomic sequence information. Evolutionary events, like gene duplication, loss, and deep coalescence, account more then ever for incongruence between gene trees and the actual species tree. Gene tree reconciliation is addressing this fundamental problem by invoking the minimum number of gene duplication and losses that reconcile a rooted gene tree with a rooted species tree. However, the reconciliation process is highly sensitive to topological error or wrong rooting of the gene tree, a condition that is not met by most gene trees in practice. Thus, despite the promises of gene tree reconciliation, its applicability in practice is severely limited.</p> <p>Results</p> <p>We introduce the problem of reconciling unrooted and erroneous gene trees by simultaneously rooting and error-correcting them, and describe an efficient algorithm for this problem. Moreover, we introduce an error-corrected version of the gene duplication problem, a standard application of gene tree reconciliation. We introduce an effective heuristic for our error-corrected version of the gene duplication problem, given that the original version of this problem is NP-hard. Our experimental results suggest that our error-correcting approaches for unrooted input trees can significantly improve on the accuracy of gene tree reconciliation, and the species tree inference under the gene duplication problem. Furthermore, the efficiency of our algorithm for error-correcting reconciliation is capable of handling truly large-scale phylogenetic studies.</p> <p>Conclusions</p> <p>Our presented error-correction approach is a crucial step towards making gene tree reconciliation more robust, and thus to improve on the accuracy of applications that fundamentally rely on gene tree reconciliation, like the inference of gene-duplication supertrees.</p

AST: An Automated Sequence-Sampling Method for Improving the Taxonomic Diversity of Gene Phylogenetic Trees

A challenge in phylogenetic inference of gene trees is how to properly sample a large pool of homologous sequences to derive a good representative subset of sequences. Such a need arises in various applications, e.g. when (1) accuracy-oriented phylogenetic reconstruction methods may not be able to deal with a large pool of sequences due to their high demand in computing resources; (2) applications analyzing a collection of gene trees may prefer to use trees with fewer operational taxonomic units (OTUs), for instance for the detection of horizontal gene transfer events by identifying phylogenetic conflicts; and (3) the pool of available sequences is biased towards extensively studied species. In the past, the creation of subsamples often relied on manual selection. Here we present an Automated sequence-Sampling method for improving the Taxonomic diversity of gene phylogenetic trees, AST, to obtain representative sequences that maximize the taxonomic diversity of the sampled sequences. To demonstrate the effectiveness of AST, we have tested it to solve four problems, namely, inference of the evolutionary histories of the small ribosomal subunit protein S5 of E. coli, 16 S ribosomal RNAs and glycosyl-transferase gene family 8, and a study of ancient horizontal gene transfers from bacteria to plants. Our results show that the resolution of our computational results is almost as good as that of manual inference by domain experts, hence making the tool generally useful to phylogenetic studies by non-phylogeny specialists. The program is available at http://csbl.bmb.uga.edu/~zhouchan/AST.php

Broadly sampled multigene analyses yield a well-resolved eukaryotic tree of life

Author Posting. © The Authors, 2010. This is the author's version of the work. It is posted here by permission of Oxford University Press for personal use, not for redistribution. The definitive version was published in Systematic Biology 59 (2010): 518-533, doi:10.1093/sysbio/syq037.An accurate reconstruction of the eukaryotic tree of life is essential to identify the innovations underlying the diversity of microbial and macroscopic (e.g. plants and animals) eukaryotes. Previous work has divided eukaryotic diversity into a small number of high-level ‘supergroups’, many of which receive strong support in phylogenomic analyses. However, the abundance of data in phylogenomic analyses can lead to highly supported but incorrect relationships due to systematic phylogenetic error. Further, the paucity of major eukaryotic lineages (19 or fewer) included in these genomic studies may exaggerate systematic error and reduces power to evaluate hypotheses. Here, we use a taxon-rich strategy to assess eukaryotic relationships. We show that analyses emphasizing broad taxonomic sampling (up to 451 taxa representing 72 major lineages) combined with a moderate number of genes yield a well-resolved eukaryotic tree of life. The consistency across analyses with varying numbers of taxa (88-451) and levels of missing data (17-69%) supports the accuracy of the resulting topologies. The resulting stable topology emerges without the removal of rapidly evolving genes or taxa, a practice common to phylogenomic analyses. Several major groups are stable and strongly supported in these analyses (e.g. SAR, Rhizaria, Excavata), while the proposed supergroup ‘Chromalveolata’ is rejected. Further, extensive instability among photosynthetic lineages suggests the presence of systematic biases including endosymbiotic gene transfer from symbiont (nucleus or plastid) to host. Our analyses demonstrate that stable topologies of ancient evolutionary relationships can be achieved with broad taxonomic sampling and a moderate number of genes. Finally, taxonrich analyses such as presented here provide a method for testing the accuracy of relationships that receive high bootstrap support in phylogenomic analyses and enable placement of the multitude of lineages that lack genome scale data

Single charge carrier type sensing with a parallel strip pseudo-Frisch-grid CdZnTe semiconductor radiation detector

An improvement in gamma-ray energy resolution is demonstrated for a room-temperature operated CdZnTe semiconductor detector that incorporates a parallel strip pseudo-Frisch-grid detector design. The device construction allows primarily for the measurement of electron charge carriers and not hole charge carriers. The detector is a three-terminal device that requires signal output to only one preamplifier, and its simplistic design offers an alternative method to single charge carrier type sensing to that of coplanar semiconductor gamma-ray detector designs. © 1998 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69858/2/APPLAB-72-7-792-1.pd