Sets of lines and cutting out polyhedral objects

AbstractWe study algorithmic questions related to cutting polyhedral shapes with a hot wire cutter. Such cutters are popular manufacturing tools for cutting expanded polystyrene (styrofoam) with a thin, moving heated wire. In particular, we study the question of polyhedral-wise continuity: Can a given object be cut out without disconnecting and then reattaching the wire? In an abstract setting this question translates to properties of sets of lines and segments and therefore becomes suitable for computational geometry techniques. On the combinatorial and algorithmic levels the results and methods are related to two problems: (1) given a set F={f1,…,fk} of polygons and a polygon f, decide if there is a subset of lines in the set of lines not stabbing F that cover f; (2) construct the connectivity graph for free movements of lines that maintain contact with the polyhedral shape. Problem (1) is solved with the dual projection and arrangements of convex and concave x-monotone curves. Problem (2) can be solved with a combination of the skewed projections [6] and hyperbola arrangements proposed by McKenna and O'Rourke [11]. We provide an O(n5) algorithm for constructing a cutting path, if it exists. The complexity of the algorithm is determined by the O(n4) size of the connectivity graph and the cost of solving (2)

Experimenting with database segmentation size vs time performance for mpiBLAST on an IBM HS21 blade cluster

Large-scale genomic projects such as the Epichloë festucae Genome Project require regular use of bioinformatic tools. When using BLAST in conjunction with larger databases, processing complex sequences often uses substantial computation time. Parallelization is considered a standard method of curbing extensive computing requirements and parallel implementations of BLAST, such as mpiBLAST, are freely available

MedSurv: a software application for creating, conducting and managing medical surveys and questionnaires

MedSurv is a system designed for the rapid creation and maintenance of research surveys and questionnaires that does not require programmer intervention. MedSurv is built with medical surveys in mind and utilizes a group-based permission control with additional security features to help ensure compliance with applicable healthcare regulations. MedSurv is designed as a module for DotNetNuke [1], an open source portal and content management system built with ASP.Net technology, and therefore can be deployed and managed as intranet, extranet, and web sites. At the same time, all data is stored at the researcher\u27s institution to guarantee the required data privacy. Thanks to its built-in support for user authentication and user roles, there is no need to create such functionality from scratch. However, a group-based permissions system is added to MedSurv to support sufficient granularity for access control. Although from the data access point of view data storage acts as a relational table, MedSurv uses a solution that we call virtual tables. The premise behind such a solution is that the structure of the tables is itself stored in a set of relational tables within the database, essentially creating a miniature database within the database. This additional layer is transparent to the user and removes the need for any programming or database knowledge. At the same time it gives the user the flexibility of changing the survey at runtime. Unlike a traditional structure that may require database developer\u27s involvement each time a survey is added or changed, with virtual tables there is very low developer and database administration need after launch. MedSurv allows for creating complex medical surveys and is, in particular, used to develop questionnaires for research driven data collection in the Department of Gastroenterology

Statistical Phylogenetic Tree Analysis Using Differences of Means

We propose a statistical method to test whether two phylogenetic trees with given alignments are significantly incongruent. Our method compares the two distributions of phylogenetic trees given by the input alignments, instead of comparing point estimations of trees. This statistical approach can be applied to gene tree analysis for example, detecting unusual events in genome evolution such as horizontal gene transfer and reshuffling. Our method uses difference of means to compare two distributions of trees, after embedding trees in a vector space. Bootstrapping alignment columns can then be applied to obtain p-values. To compute distances between means, we employ a "kernel trick" which speeds up distance calculations when trees are embedded in a high-dimensional feature space, e.g. splits or quartets feature space. In this pilot study, first we test our statistical method's ability to distinguish between sets of gene trees generated under coalescence models with species trees of varying dissimilarity. We follow our simulation results with applications to various data sets of gophers and lice, grasses and their endophytes, and different fungal genes from the same genome. A companion toolkit, {\tt Phylotree}, is provided to facilitate computational experiments.Comment: 17 pages, 6 figure

\u3cem\u3ePhylotree\u3c/em\u3e – a toolkit for computing experiments with distance-based methods for genome coevolution

We have developed software called Phylotree as a toolkit for running experiments to study gene cophylogenies for genome evolution using distance-based methods. In particular, the toolkit has been instrumental in conducting processing-heavy experiments with the new “difference of means” statistical method. Phylotree was used to run experiments using simulated data as well as biological sequences of well known host and parasite species, and is distributed with data and configuration files allowing these experiments to be reproduced

Phylotree – a toolkit for computing experiments with distance-based methods for genome coevolution

We have developed software called Phylotree as a toolkit for running experiments to study gene cophylogenies for genome evolution using distance-based methods. In particular, the toolkit has been instrumental in conducting processing-heavy experiments with the new “difference of means” statistical method. Phylotree was used to run experiments using simulated data as well as biological sequences of well known host and parasite species, and is distributed with data and configuration files allowing these experiments to be reproduced

Automating Deployment of Several GBrowse Instances

Background As part of the fungal endophyte genomes project, we maintain genome browsers for several dozen strains of fungi from the Clavicipitaceae and related families. These genome browsers are based on the GBrowse software, with a large collection of in-house software for visualization, analysis, and searching of genome features. Although GBrowse supports serving multiple data sources, such as distinct genome assemblies, from a single GBrowse instance, there are advantages to maintaining separate instances for each genome. Besides permitting per-genome customizations of the software, page layout, and database schemas, our use of separate instances also allows us to maintain different security and password requirements for genomes in different stages of publication. Materials and methods We have developed a suite of software for deploying and maintaining a large collection of GBrowse instances. This software, a combination of Perl, shell libraries, and scripts, automates the process of deploying the software, databases, and configuration required to make a new customized genome browser available online; and furthermore automates loading each instance’s database with genome sequences, annotations, and other data. To maintain a mostly synchronized codebase while allowing distinct configuration, we record each instance’s software and configuration as a branch in a Subversion version control repository. This use of version control ensures that bug fixes and software improvements are easily applied to each relevant instance, without losing customizations. Results We describe the components of our genome browser instances, the design and implementation of our deployment software, and various challenges and practical considerations we have encountered while using this software to maintain genome browsers for nearly fifty organism strains and assembly versions

Swainsonine Biosynthesis Genes in Diverse Symbiotic and Pathogenic Fungi

Swainsonine—a cytotoxic fungal alkaloid and a potential cancer therapy drug—is produced by the insect pathogen and plant symbiont Metarhizium robertsii, the clover pathogen Slafractonia leguminicola, locoweed symbionts belonging to Alternaria sect. Undifilum, and a recently discovered morning glory symbiont belonging to order Chaetothyriales. Genome sequence analyses revealed that these fungi share orthologous gene clusters, designated “SWN,” which included a multifunctional swnKgene comprising predicted adenylylation and acyltransferase domains with their associated thiolation domains, a β-ketoacyl synthase domain, and two reductase domains. The role of swnK was demonstrated by inactivating it in M. robertsii through homologous gene replacement to give a ∆swnK mutant that produced no detectable swainsonine, then complementing the mutant with the wild-type gene to restore swainsonine biosynthesis. Other SWN cluster genes were predicted to encode two putative hydroxylases and two reductases, as expected to complete biosynthesis of swainsonine from the predicted SwnK product. SWN gene clusters were identified in six out of seven sequenced genomes of Metarhzium species, and in all 15 sequenced genomes of Arthrodermataceae, a family of fungi that cause athlete’s foot and ringworm diseases in humans and other mammals. Representative isolates of all of these species were cultured, and all Metarhizium spp. with SWN clusters, as well as all but one of the Arthrodermataceae, produced swainsonine. These results suggest a new biosynthetic hypothesis for this alkaloid, extending the known taxonomic breadth of swainsonine producers to at least four orders of Ascomycota, and suggest that swainsonine has roles in mutualistic symbioses and diseases of plants and animals