5,023 research outputs found

    Structural Analysis of Polarizing Indels Argues the Root of the Tree of Life is Near the Chloroflexi

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    Determining which branches of the tree of life have derived features narrows down the possible location of the root. Currently the polarization of indels done by Lake _et al_.^1-5^ and the polarizing transitions of Cavalier-Smith^6^ arrive at contradictory positions for the root of the tree. We have analyzed the sequence based indel arguments using protein structure wherever possible. Structure strongly supports some of the polarizations, but in other indels it argues for a different conclusion. We conclude that there is no contradiction between Lake _et al_. and Cavalier-Smith; the root of the tree of life must be near the Chloroflexi.
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    Save the tree of life or get lost in the woods

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    <p>Abstract</p> <p>Background</p> <p>The wealth of prokaryotic genomic data available has revealed that the histories of many genes are inconsistent, leading some to question the value of the tree of life hypothesis. It has been argued that a tree-like representation requires suppressing too much information, and that a more pluralistic approach is necessary for understanding prokaryotic evolution. We argue that trees may still be a useful representation for evolutionary histories in light of new data.</p> <p>Results</p> <p>Genomic data alone can be highly misleading when trying to resolve the tree of life. We present evidence from protein abundance data sets that genomic conservation greatly underestimates functional conservation. Function follows more of a tree-like structure than genetic material, even in the presence of horizontal transfer. We argue that the tree of cells must be incorporated into any new synthesis in order to place horizontal transfers into their proper selective context. We also discuss the role data sources other than primary sequence can play in resolving the tree of cells.</p> <p>Conclusions</p> <p>The tree of life is alive, but not well. Construction of the tree of cells has been viewed as the end goal of the study of evolution, where in reality we need to consider it more of a starting point. We propose a duality where we must consider variation of genetic material in terms of networks and selection of cellular function in terms of trees. Otherwise one gets lost in the woods of neutral evolution.</p> <p>Reviewers</p> <p>This article was reviewed by Dr. Eric Bapteste, Dr. Arcady Mushegian, and Dr. Celine Brochier.</p

    Intraoperative Extracorporeal Irradiation for the Treatment of the Meningioma-Infiltrated Calvarium.

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    Objectives Complete removal of infiltrated bone is required to achieve a Simpson Grade 1 meningioma resection. Reconstruction of the resulting bone defect is typically achieved with a nonnative implant that can result in poor cosmesis, foreign body reaction, or infection. Extracorporeal irradiation and reimplantation of tumorous bone has been used for limb-sparing surgery with excellent results, but this treatment option is not routinely considered in meningioma surgery. We present a case of anterior fossa meningioma with tumorous overlying calvarium that was successfully managed with intraoperative extracorporeal irradiation and reimplantation. Design, Setting, and Participant A 37-year-old woman with persistent chronic headaches was found to have an anterior skull base meningioma with extension into the forehead frontal bone. Concurrently with mass resection, the bone flap was irradiated intraoperatively with 120 Gy. After resection of the tumor, the bone flap was replaced in its native position. Main Outcome Measures and Results Twenty-nine months postoperatively, the patient had an excellent cosmetic outcome with no radiographic evidence of tumor recurrence or significant bone flap resorption. Conclusion Intraoperative extracorporeal irradiation of tumorous calvaria during meningioma surgery is an effective, logistically feasible treatment option to achieve local tumor control and excellent cosmetic outcome

    Results on Transversal and Axial Motions of a System of Two Beams Coupled to a Joint through Two Legs

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    In recent years there has been renewed interest in inflatable-rigidizable space structures because of the efficiency they offer in packaging during boost-to-orbit. However, much research is still needed to better understand dynamic response characteristics, including inherent damping, of truss structures fabricated with these advanced material systems. We present results of an ongoing research related to a model consisting of an assembly of two beams with Kelvin-Voight damping, coupled to a simple joint through two legs. The beams are clamped at one end but at the other end they satisfy a boundary condition given in terms of an ODE coupling boundary terms of both beams, which reflects geometric compatibility conditions. The system is then written as a second order differential equation in an appropriate Hilbert space  in which well-posedness, exponential stability as well as other regularity properties of the solutions can be obtained. Two different finite dimensional approximation schemes for the solutions of the system are presented. Numerical results are presented and comparisons are made.Fil: Burns, J. A.. Interdisciplinary Center for Applied Mathematics; Estados UnidosFil: Cliff, E. M.. Interdisciplinary Center for Applied Mathematics; Estados UnidosFil: Liu, Z.. University of Minnesota at Duluth; Estados UnidosFil: Spies, Ruben Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Matemática Aplicada del Litoral. Universidad Nacional del Litoral. Instituto de Matemática Aplicada del Litoral; Argentin
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