2,182 research outputs found

    Geometric realizations, curvature decompositions, and Weyl manifolds

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    We show any Weyl curvature model can be geometrically realized by a Weyl manifol

    Notes on Chern's Affine Bernstein Conjecture

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    There were two famous conjectures on complete affine maximal surfaces, one due to E. Calabi, the other to S.S. Chern. Both were solved with different methods about one decade ago by studying the associated Euler-Lagrange equation. Here we survey two proofs of Chern's conjecture in our recent monograph [L-X-S-J], in particular we add some details of the proofs of auxiliary material that were omitted in [L-X-S-J]. We describe the related background in our Introduction. Our survey is suitable as a report about recent developments and techniques in the study of certain Monge-Ampere equations

    Complete Genome Sequence of Bacteroides ovatus V975

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    The complete genome sequence of Bacteroides ovatus V975 was determined. The genome consists of a single circular chromosome of 6,475,296 bp containing five rRNA operons, 68 tRNA genes, and 4,959 coding genes

    Use of genetically modified bacteria for drug delivery in humans: Revisiting the safety aspect

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    The use of live, genetically modified bacteria as delivery vehicles for biologics is of considerable interest scientifically and has attracted significant commercial investment. We have pioneered the use of the commensal gut bacterium Bacteroides ovatus for the oral delivery of therapeutics to the gastrointestinal tract. Here we report on our investigations of the biological safety of engineered B. ovatus bacteria that includes the use of thymineless death as a containment strategy and the potential for the spread of transgenes in vivo in the mammalian gastrointestinal tract. We demonstrate the ability of GM-strains of Bacteroides to survive thymine starvation and overcome it through the exchange of genetic material. We also provide evidence for horizontal gene transfer in the mammalian gastrointestinal tract resulting in transgene-carrying wild type bacteria. These findings sound a strong note of caution on the employment of live genetically modified bacteria for the delivery of biologics

    On the Design of Peer Punishment Experiments

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    We discuss how technologies of peer punishment might bias the results that are observed in experiments. A crucial parameter is the “fine-to-fee” ratio, which describes by how much the punished subjects income is reduced relatively to the fee the punishing subject has to pay to inflict punishment. We show that a punishment technology commonly used in experiments embeds a variable fine-to-fee ratio and show that it confounds the empirical findings about why, whom, and how much subjects punish

    American College of Cardiology/ European Society of Cardiology international study of angiographic data compression phase III Measurement of image quality differences at varying levels of data compression

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    AbstractOBJECTIVESWe sought to investigate up to which level of Joint Photographic Experts Group (JPEG) data compression the perceived image quality and the detection of diagnostic features remain equivalent to the quality and detectability found in uncompressed coronary angiograms.BACKGROUNDDigital coronary angiograms represent an enormous amount of data and therefore require costly computerized communication and archiving systems. Earlier studies on the viability of medical image compression were not fully conclusive.METHODSTwenty-one raters evaluated sets of 91 cine runs. Uncompressed and compressed versions of the images were presented side by side on one monitor, and image quality differences were assessed on a scale featuring six scores. In addition, the raters had to detect pre-defined clinical features. Compression ratios (CR) were 6:1, 10:1 and 16:1. Statistical evaluation was based on descriptive statistics and on the equivalence t-test.RESULTSAt the lowest CR (CR 6:1), there was already a small (15%) increase in assigning the aesthetic quality score indicating “quality difference is barely discernible—the images are equivalent.” At CR 10:1 and CR 16:1, close to 10% and 55%, respectively, of the compressed images were rated to be “clearly degraded, but still adequate for clinical use” or worse. Concerning diagnostic features, at CR 10:1 and CR 16:1 the error rate was 9.6% and 13.1%, respectively, compared with 9% for the baseline error rate in uncompressed images.CONCLUSIONSCompression at CR 6:1 provides equivalence with the original cine runs. If CR 16:1 were used, one would have to tolerate a significant increase in the diagnostic error rate over the baseline error rate. At CR 10:1, intermediate results were obtained

    Kreislaufanlagen - Positionen des Ökosektors

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    Geeignete Standorte für herkömmliche Formen der Aquakultur werden weltweit knapp, und eine Erhöhung der Produktion gerät zunehmend mit Zielen des Umwelt- und Naturschutzes in Konflikt. Der in Deutschland extrem geringe Selbstversorgungsgrad mit Fisch kann daher in erster Linie über eine Produktionssteigerung in Kreislaufanlagen (KLA), d.h. in geschlossenen, standortunabhängigen und entsprechend technisierten Systemen, erhöht werden. Im Nationalen Strategieplan Aquakultur für Deutschland wird insofern ein besonderer Fokus auf das Produktionspotential in KLA gelegt, bzw. ein deutliches Wachstum nur in diesem Bereich (Steigerung auf 20.000 t bis 2020) als möglich erachtet. Bei dem hier beantragten Vorhaben wird geklärt, wie relevante Interessensgruppen die Vereinbarkeit von Aquakultur in KLA mit der Ökologischen Lebensmittelwirtschaft bewerten. Die Frage stellt sich einerseits aus Sicht der Erzeuger, denn die Produktion in KLA ist durch hohe Umweltauflagen sowie komplexe Haltungssysteme aufwändig und benötigt daher Wege, ihre Alleinstellungsmerkmale (z.B. Transparenz, Regionalität, Verzicht auf Chemie und Tierarznei) auf glaubhaftem Weg an den Verbraucher zu kommunizieren. Andererseits aus Sicht der richtliniengebenden Ökoverbände und Institutionen, denn sie sind von Seiten des Marktes und der Gesellschaft aufgefordert, zu dieser immer wichtiger werdenden Zukunftstechnologie fundiert Stellung zu beziehen

    Individual Effector/Regulator T Cell Ratios Impact Bone Regeneration

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    There is increasing evidence that T lymphocytes play a key role in controlling endogenous regeneration. Regeneration appears to be impaired in case of local accumulation of CD8+ effector T cells (TEFF), impairing endogenous regeneration by increasing a primary "useful" inflammation toward a damaging level. Thus, rescuing regeneration by regulating the heightened pro-inflammatory reaction employing regulatory CD4+ T (TReg) cells could represent an immunomodulatory option to enhance healing. Hypothesis was that CD4+ TReg might counteract undesired effects of CD8+ TEFF. Using adoptive TReg transfer, bone healing was consistently improved in mice possessing an inexperienced immune system with low amounts of CD8+ TEFF. In contrast, mice with an experienced immune system (high amounts of CD8+ TEFF) showed heterogeneous bone repair with regeneration being dependent upon the individual TEFF/TReg ratio. Thus, the healing outcome can only be improved by an adoptive TReg therapy, if an unfavorable TEFF/TReg ratio can be reshaped; if the individual CD8+ TEFF percentage, which is dependent on the individual immune experience can be changed toward a favorable ratio by the TReg transfer. Remarkably, also in patients with impaired fracture healing the TEFF/TReg ratio was higher compared to uneventful healers, validating our finding in the mouse osteotomy model. Our data demonstrate for the first time the key-role of a balanced TEFF/TReg response following injury needed to reach successful regeneration using bone as a model system. Considering this strategy, novel opportunities for immunotherapy in patients, which are at risk for impaired healing by targeting TEFF cells and supporting TReg cells to enhance healing are possible

    Cardiovascular magnetic resonance risk stratification in patients with clinically suspected myocarditis

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    BACKGROUND: The diagnosis of myocarditis is challenging due to its varying clinical presentation. Since myocarditis can be associated with significant 5-year mortality, and postmortem data show myocarditis in almost 10% of all adults suffering sudden cardiac death, individual risk stratification for patients with suspected myocarditis is of great clinical interest. We sought to demonstrate that patients with clinically suspected myocarditis and a normal cardiovascular magnetic resonance (CMR) according to our definition have a good prognosis, independent of their clinical symptoms and other findings. METHODS: Prospective clinical long-term follow-up of consecutive patients undergoing CMR for work-up of clinically suspected myocarditis at our institution in 2007-2008. RESULTS: Follow-up was available for n = 405 patients (all-comers, 54.8% inpatients, 38% outpatient referrals from cardiologists). Median follow-up time was 1591 days. CMR diagnosis was “myocarditis” in 28.8%, “normal” in 55.6% and “other pathology” in 15.6%. Normal CMR was defined as normal left ventricular (LV) volumes and normal left ventricular ejection fraction (LV-EF) in the absence of late Gadolinium Enhancement (LGE). The overall mortality was 3.2%. There were seven cardiac deaths during follow-up, in addition one aborted SCD and two patients had appropriate internal cardioverter defibrillator (ICD) shocks – all of these occurred in patients with abnormal CMR. Kaplan-Meier analysis with log-rank test showed significant difference for major adverse cardiac events (cardiac death, sudden cardiac death (SCD), ICD discharge, aborted SCD) between patients with normal and abnormal CMR (p = 0.0003). CONCLUSION: In our unselected population of consecutive patients referred for CMR work-up of clinically suspected myocarditis, patients with normal CMR have a good prognosis independent of their clinical symptoms and other findings
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