Evidence, Content and Corroboration and the Tree of Life

We examine three critical aspects of Popper’s formulation of the ‘Logic of Scientific Discovery’—evidence, content and degree of corroboration—and place these concepts in the context of the Tree of Life (ToL) problem with particular reference to molecular systematics. Content, in the sense discussed by Popper, refers to the breadth and scope of existence that a hypothesis purports to explain. Content, in conjunction with the amount of available and relevant evidence, determines the testability, or potential degree of corroboration, of a statement; content distinguishes scientific hypotheses from metaphysical assertions. Degree of corroboration refers to the relative and tentative confidence assigned to one hypothesis over another, based upon the performance of each under critical tests. Here we suggest that systematists attempt to maximize content and evidence to increase the potential degree of corroboration in all phylogenetic endeavors. Discussion of this “total evidence” approach leads to several interesting conclusions about generating ToL hypotheses

Zur Diagnostik des Diabetes insipidus unter besonderer Berücksichtigung hypophysektomierter Patienten

Verschiedene, am gleichen Patienten durchgeführte Stimulationsteste für die ADH-Sekretion (17-Std.-Durstversuch, Carter-Robbins-Test, osmotische Diurese) zeigen eine ausgezeichnete Korrelation. Auf Grund dieser Ergebnisse werden Richtlinien zur möglichst einfachen Diagnostik einer Konzentrationsstörung vorgeschlagen. In den meisten Fällen kann allein schon auf Grund eines exakt durchgeführten Durstversuchs eine Konzentrationsstörung nachgewiesen (höchste Urinosmolalität 750 mOsm/kg) werden. Lediglich bei einer höchsten Urinosmolalität im 17-Std.-Durstversuch zwischen 500 und 750 mOsm/kg müssen aufwendigere und den Patienten mehr belastende Tests (z. B. Carter-Robbins-Test) eingesetzt werden, um das Vorliegen bzw. den Grad einer Konzentrationsstörung endgültig diagnostizieren zu können. ADH-Injektionen dienen dabei zur Differenzierung zwischen einem ADH-Mangel und einer mangelhaften ADH-Ansprechbarkeit der Niere. Unsere Untersuchungen an hypophysektomierten Patienten (N=29) zeigen auch bei Patienten ohne polyurisch-polydiptisches Syndrom (N=22) eine gegenüber Normalpersonen signifikant eingeschränkte Konzentrationsleistung im 17-Std.-Durstversuch.The results of three different stimulation tests for ADH (17 hours thirst period, Carter-Robbins-test, osmotic diuresis) correlate well in the same patient. Because of this we propose a simplified procedure for the detection of failure to produce a concentrated urine. In most cases merely on the basis of a precisely executed thirst period test, one can either recognize an abnormality of concentration (highest urine osmolality less than 500 mOsm/kg), or exlude it (highest urine osmolality greater than 750 mOsm/kg). Only when the highest urine osmolality lies between 500 and 750 mOsm/kg after a 17 hour thirst must more painstaking tests (e.g. Carter-Robbins test) be employed to determine both the presence of and the degree of a failure to produce a concentrated urine. An injection of ADH can be used to differentiate between a deficiency of ADH and a defective response of the kidneys to ADH. Our investigations on hypophysectomized patients (n=29) showed that also in patients without the syndrome of polyuria-polydypsia (n=22), there was a significantly reduced capacity to concentrate urine during a 17 hour thirst period, as compared with normal people

A format for phylogenetic placements

We have developed a unified format for phylogenetic placements, that is, mappings of environmental sequence data (e.g. short reads) into a phylogenetic tree. We are motivated to do so by the growing number of tools for computing and post-processing phylogenetic placements, and the lack of an established standard for storing them. The format is lightweight, versatile, extensible, and is based on the JSON format which can be parsed by most modern programming languages. Our format is already implemented in several tools for computing and post-processing parsimony- and likelihood-based phylogenetic placements, and has worked well in practice. We believe that establishing a standard format for analyzing read placements at this early stage will lead to a more efficient development of powerful and portable post-analysis tools for the growing applications of phylogenetic placement.Comment: Documents version 3 of the forma

HITRAP: A facility at GSI for highly charged ions

An overview and status report of the new trapping facility for highly charged ions at the Gesellschaft fuer Schwerionenforschung is presented. The construction of this facility started in 2005 and is expected to be completed in 2008. Once operational, highly charged ions will be loaded from the experimental storage ring ESR into the HITRAP facility, where they are decelerated and cooled. The kinetic energy of the initially fast ions is reduced by more than fourteen orders of magnitude and their thermal energy is cooled to cryogenic temperatures. The cold ions are then delivered to a broad range of atomic physics experiments.Comment: 8 pages, 11 figure

Status and overview of development of the Silicon Pixel Detector for the PHENIX experiment at the BNL RHIC

We have developed a silicon pixel detector to enhance the physics capabilities of the PHENIX experiment. This detector, consisting of two layers of sensors, will be installed around the beam pipe at the collision point and covers a pseudo-rapidity of | \eta | < 1.2 and an azimuth angle of | \phi | ~ 2{\pi}. The detector uses 200 um thick silicon sensors and readout chips developed for the ALICE experiment. In order to meet the PHENIX DAQ readout requirements, it is necessary to read out 4 readout chips in parallel. The physics goals of PHENIX require that radiation thickness of the detector be minimized. To meet these criteria, the detector has been designed and developed. In this paper, we report the current status of the development, especially the development of the low-mass readout bus and the front-end readout electronics.Comment: 9 pages, 8 figures and 1 table in DOCX (Word 2007); PIXEL 2008 workshop proceedings, will be published in the Proceedings Section of JINST(Journal of Instrumentation