693 research outputs found

    An absolute calibration system for millimeter-accuracy APOLLO measurements

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    Lunar laser ranging provides a number of leading experimental tests of gravitation -- important in our quest to unify General Relativity and the Standard Model of physics. The Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) has for years achieved median range precision at the ~2 mm level. Yet residuals in model-measurement comparisons are an order-of-magnitude larger, raising the question of whether the ranging data are not nearly as accurate as they are precise, or if the models are incomplete or ill-conditioned. This paper describes a new absolute calibration system (ACS) intended both as a tool for exposing and eliminating sources of systematic error, and also as a means to directly calibrate ranging data in-situ. The system consists of a high-repetition-rate (80 MHz) laser emitting short (< 10 ps) pulses that are locked to a cesium clock. In essence, the ACS delivers photons to the APOLLO detector at exquisitely well-defined time intervals as a "truth" input against which APOLLO's timing performance may be judged and corrected. Preliminary analysis indicates no inaccuracies in APOLLO data beyond the ~3 mm level, suggesting that historical APOLLO data are of high quality and motivating continued work on model capabilities. The ACS provides the means to deliver APOLLO data both accurate and precise below the 2 mm level.Comment: 21 pages, 10 figures, submitted to Classical and Quantum Gravit

    The relationship between quality of life (EORTC QLQ-C30) and survival in patients with gastro-oesopohageal cancer

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    It remains unclear whether any aspect of quality of life has a role in predicting survival in an unselected cohort of patients with gastro-oesophageal cancer. Therefore the aim of the present study was to examine the relationship between quality of life (EORTC QLQ-C30), clinico-pathological characteristics and survival in patients with gastro-oesophageal cancer. Patients presenting with gastric or oesophageal cancer, staged using the UICC tumour node metastasis (TNM) classification and who received either potentially curative surgery or palliative treatment between November 1997 and December 2002 (n=152) participated in a quality of life study, using the EORTC QLQ-C30 core questionnaire. On univariate analysis, age (P &#60; 0.01), tumour length (P &#60; 0.0001), TNM stage (P&#60;0.0001), weight loss (P&#60;0.0001), dysphagia score (P&#60;0.001), performance status (P&#60;0.1) and treatment (P&#60;0.0001) were significantly associated with cancer-specific survival. EORTC QLQ-C30, physical functioning (P&#60;0.0001), role functioning (P&#60;0.001), cognitive functioning (P&#60;0.01), social functioning (P&#60;0.0001), global quality of life (P&#60;0.0001), fatigue (P&#60;0.0001), nausea/vomiting (P&#60;0.01), pain (P&#60;0.001), dyspnoea (P&#60;0.0001), appetite loss (P&#60;0.0001) and constipation (P&#60;0.05) were also significantly associated with cancer-specific survival. On multivariate survival analysis, tumour stage (P&#60;0.0001), treatment (P&#60;0.001) and appetite loss (P&#60;0.0001) were significant independent predictors of cancer-specific survival. The present study highlights the importance of quality of life (EORTC QLQ-C30) measures, in particular appetite loss, as a prognostic factor in these patients

    Tricritical Points in the Sherrington-Kirkpatrick Model in the Presence of Discrete Random Fields

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    The infinite-range-interaction Ising spin glass is considered in the presence of an external random magnetic field following a trimodal (three-peak) distribution. The model is studied through the replica method and phase diagrams are obtained within the replica-symmetry approximation. It is shown that the border of the ferromagnetic phase may present first-order phase transitions, as well as tricritical points at finite temperatures. Analogous to what happens for the Ising ferromagnet under a trimodal random field, it is verified that the first-order phase transitions are directly related to the dilution in the fields (represented by p0p_{0}). The ferromagnetic boundary at zero temperature also exhibits an interesting behavior: for 0<p0<p0∗≈0.308560<p_{0}<p_{0}^{*} \approx 0.30856, a single tricritical point occurs, whereas if p0>p0∗p_{0}>p_{0}^{*} the critical frontier is completely continuous; however, for p0=p0∗p_{0}=p_{0}^{*}, a fourth-order critical point appears. The stability analysis of the replica-symmetric solution is performed and the regions of validity of such a solution are identified; in particular, the Almeida-Thouless line in the plane field versus temperature is shown to depend on the weight p0p_{0}.Comment: 23pages, 7 ps figure

    An elevated C-reactive protein concentration, prior to surgery, predicts poor cancer-specific survival in patients undergoing resection for gastro-oesophageal cancer

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    There is increasing evidence that the presence of an ongoing systemic inflammatory response is associated with poor outcome in patients undergoing resection for a variety of tumours. The aim of the present study was to examine the relationship between clinico-pathological status, preoperative C-reactive protein concentration and cancer-specific survival in patients undergoing resection for gastro-oesophageal cancer. One hundred and twenty patients attending the upper gastrointestinal surgical unit in the Royal Infirmary, Glasgow, who were selected for potentially curative surgery, were included in the study. Laboratory measurements of haemoglobin, white cell, lymphocyte and platelet counts, albumin and C-reactive protein were carried out at the time of diagnosis. All patients underwent en-bloc resection with lymphadenectomy and survived at least 30 days following surgery. On multivariate analysis, only the positive to total lymph node ratio (hazard ratio (HR) 2.02, 95% confidence interval (CI) 1.44–2.84, P<0.001) and preoperative C-reactive protein concentration (HR 3.53, 95% CI 1.88–6.64, P<0.001) were independent predictors of cancer-specific survival. The patient group with no evidence of a preoperative systemic inflammatory response (C-reactive protein ⩽10 mg l−1) had a median survival of 79 months compared with 19 months in the elevated systemic inflammatory response group (P<0.001). The results of the present study indicate that in patients selected to undergo potentially curative resection for gastro-oesophageal cancer, the presence of an elevated preoperative C-reactive protein concentration is an independent predictor of poor cancer-specific survival

    The relationship between tumour T-lymphocyte infiltration, the systemic inflammatory response and survival in patients undergoing curative resection for colorectal cancer

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    There is increasing evidence that both local and systemic inflammatory responses play an important role in the progression of a variety of common solid tumours. The aim of the present study was to examine the relationship between tumour T-lymphocyte subset infiltration, the systemic inflammatory response and cancer-specific survival in patients with colorectal cancer. In all, 147 patients undergoing potentially curative resection for colorectal cancer were studied. Circulating concentrations of C-reactive protein were measured prior to surgery. CD4+ and CD8+ T-lymphocyte infiltration of the tumour was assessed using immunohistochemistry and a point counting technique. When patients were grouped according to the percentage tumour volume of CD4+ T-lymphocytes, there was no difference in terms of age, sex, tumour site, stage and tumour characteristics. However, there was an inverse relationship between percentage tumour CD4+ T-lymphocytes and C-reactive protein (P<0.01). On univariate analysis, both C-reactive protein concentrations (P<0.001) and percentage tumour volume of CD4+ (P<0.05) T-lymphocytes were associated with cancer-specific survival. The results of the present study show that low tumour CD4+ T-lymphocyte infiltration is associated with elevated C-reactive protein concentrations and both predict poor cancer-specific survival

    Comparative analysis and visualization of multiple collinear genomes

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    Abstract Background Genome browsers are a common tool used by biologists to visualize genomic features including genes, polymorphisms, and many others. However, existing genome browsers and visualization tools are not well-suited to perform meaningful comparative analysis among a large number of genomes. With the increasing quantity and availability of genomic data, there is an increased burden to provide useful visualization and analysis tools for comparison of multiple collinear genomes such as the large panels of model organisms which are the basis for much of the current genetic research. Results We have developed a novel web-based tool for visualizing and analyzing multiple collinear genomes. Our tool illustrates genome-sequence similarity through a mosaic of intervals representing local phylogeny, subspecific origin, and haplotype identity. Comparative analysis is facilitated through reordering and clustering of tracks, which can vary throughout the genome. In addition, we provide local phylogenetic trees as an alternate visualization to assess local variations. Conclusions Unlike previous genome browsers and viewers, ours allows for simultaneous and comparative analysis. Our browser provides intuitive selection and interactive navigation about features of interest. Dynamic visualizations adjust to scale and data content making analysis at variable resolutions and of multiple data sets more informative. We demonstrate our genome browser for an extensive set of genomic data sets composed of almost 200 distinct mouse laboratory strains

    Dioxin Toxicity In Vivo Results from an Increase in the Dioxin-Independent Transcriptional Activity of the Aryl Hydrocarbon Receptor

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    The Aryl hydrocarbon receptor (Ahr) is the nuclear receptor mediating the toxicity of dioxins -widespread and persistent pollutants whose toxic effects include tumor promotion, teratogenesis, wasting syndrome and chloracne. Elimination of Ahr in mice eliminates dioxin toxicity but also produces adverse effects, some seemingly unrelated to dioxin. Thus the relationship between the toxic and dioxin-independent functions of Ahr is not clear, which hampers understanding and treatment of dioxin toxicity. Here we develop a Drosophila model to show that dioxin actually increases the in vivo dioxin-independent activity of Ahr. This hyperactivation resembles the effects caused by an increase in the amount of its dimerisation partner Ahr nuclear translocator (Arnt) and entails an increased transcriptional potency of Ahr, in addition to the previously described effect on nuclear translocation. Thus the two apparently different functions of Ahr, dioxin-mediated and dioxin-independent, are in fact two different levels (hyperactivated and basal, respectively) of a single function

    The Interstellar Environment of our Galaxy

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    We review the current knowledge and understanding of the interstellar medium of our galaxy. We first present each of the three basic constituents - ordinary matter, cosmic rays, and magnetic fields - of the interstellar medium, laying emphasis on their physical and chemical properties inferred from a broad range of observations. We then position the different interstellar constituents, both with respect to each other and with respect to stars, within the general galactic ecosystem.Comment: 39 pages, 12 figures (including 3 figures in 2 parts
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