2,117 research outputs found

    Distance to U Pegasi by the DDE Algorithm

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    A distance is found for the W UMa type binary U Pegasi, with a newly modified version of the Wilson-Devinney program (W-D) that makes use of the direct distance estimation (DDE) algorithm. The reported distance of d = 123.6pc is an average based on solutions for B and V data and a primary star temperature of 5800K. Standardized light curves (not differential), radial velocities, and a spectroscopic primary star temperature are input to the pro- gram. Differential corrections were performed for each light curve band along with the velocities for two primary temperatures that span 100K. Log10d is a model parameter like many others that are adjustable in W-D. The eclipsing binary distance agrees with the Hipparcos parallax distance and is more precise.Comment: 2 pages, 1 table, International Conference: Binaries - Key to Comprehension of the Universe, Brno, Czech Republic June 8-12, 200

    Real-time monitoring of healthy omega-3 production in micro-algae: A viability study

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    Eicosapentaenoic acid (EPA) is an omega 3 fatty-acid essential to humans, who mainly rely on fish oil as a source of EPA. Unfortunately, this is not a sustainable source

    The V471 Tauri System: A Multi-datatype Probe

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    V471 Tauri, a white dwarf--red dwarf eclipsing binary in the Hyades, is well known for stimulating development of common envelope theory, whereby novae and other cataclysmic variables form from much wider binaries by catastrophic orbit shrinkage. Our evaluation of a recent imaging search that reported negative results for a much postulated third body shows that the object could have escaped detection or may have actually been seen. The balance of evidence continues to favor a brown dwarf companion about 12 AU from the eclipsing binary. A recently developed algorithm finds unified solutions from three datatypes. New radial velocities (RVs) of the red dwarf and BV RCIC light curves are solved simultaneously along with white dwarf and red dwarf RVs from the literature, uvby data, the MOST mission light curve, and 40 years of eclipse timings. Precision-based weighting is the key to proper information balance among the various datasets. Timewise variation of modeled starspots allows unified solution of multiple data eras. Light curve amplitudes strongly suggest decreasing spottedness from 1976 to about 1980, followed by approximately constant spot coverage from 1981 to 2005. An explanation is proposed for lack of noticeable variation in 1981 light curves, in terms of competition between spot and tidal variations. Photometric spectroscopic distance is estimated. The red dwarf mass comes out larger than normal for a K2V star, and even larger than adopted in several structure and evolution papers. An identified cause for this result is that much improved red dwarf RVs curves now exist

    Neurogenic Fever after Acute Traumatic Spinal Cord Injury: A Qualitative Systematic Review.

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    STUDY DESIGN: Systematic review. OBJECTIVE: To determine the incidence, pathogenesis, and clinical outcomes related to neurogenic fevers following traumatic spinal cord injury (SCI). METHODS: A systematic review of the literature was performed on thermodysregulation secondary to acute traumatic SCI in adult patients. A literature search was performed using PubMed (MEDLINE), Cochrane Central Register of Controlled Trials, and Scopus. Using strict inclusion and exclusion criteria, seven relevant articles were obtained. RESULTS: The incidence of fever of all origins (both known and unknown) after SCI ranged from 22.5 to 71.7% with a mean incidence of 50.6% and a median incidence of 50.0%. The incidence of fever of unknown origin (neurogenic fever) ranged from 2.6 to 27.8% with a mean incidence of 8.0% and a median incidence of 4.7%. Cervical and thoracic spinal injuries were more commonly associated with fever than lumbar injuries. In addition, complete injuries had a higher incidence of fever than incomplete injuries. The pathogenesis of neurogenic fever after acute SCI is not thoroughly understood. CONCLUSION: Neurogenic fevers are relatively common following an acute SCI; however, there is little in the scientific literature to help physicians prevent or treat this condition. The paucity of research underscored by this review demonstrates the need for further studies with larger sample sizes, focusing on incidence rate, clinical outcomes, and pathogenesis of neurogenic fever following acute traumatic SCI

    Fluorescence in ultraviolet active binaries: the case of FF Aquarii

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    The eclipsing binary FF Aquarii (FF Aqr) consists of a small hot star of uncertain type and a red giant. An Hα feature varies from absorption during eclipse to maximum emission during hot star transit. We have obtained simultaneous differential photometry in BVRI bands and Hα spectroscopy in 1998 that covered an entire orbit with some overlap. A binary star model was used with our light-curve, radial velocity and Hα data to refine stellar and orbital parameters. A new ephemeris indicates that the period has increased or is longer than previously thought. A physically simple algorithm is developed that generates properly blended spectral line profiles of binaries with arbitrary combinations of surface emission and absorption line regions. Although there is no radiative transfer, the algorithm can accommodate modest geometrical intricacy. For now, all line broadening in the model is rotational. The algorithm has now been incorporated within the general Wilson-Devinney binary star model, and we used it to model FF Aqr\u27s photospheric iron profile. It also is used to generate templates that illustrate problems with FF Aqr\u27s strongly time-dependent Hα emission profiles, which appear to be blends of features from the photosphere and from above the photosphere. The dominant broadening mechanism should be rotation for individual line components. Absorption profiles were generated by the model and fit to the observations to yield a red star radius ~6.9 Rsolar, which then requires i~ 76°. Our light-curve models have five spots with temperatures ~1000 K cooler than the surrounding photosphere. Hα emission was modelled on the red star surface, centred at the substellar point to simulate a fluorescent chromosphere. Additional emission is seen outside our modelled profiles. The origins of this excess emission may be corotating prominences, winds, or coronal mass ejections, all of which could affect the orbit period

    Fluorescence and Chromospheric Activity of V471 Tau

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    The red dwarf + white dwarf eclipsing binary V471 Tau shows a variable Hα feature that varies from absorption during eclipse to maximum emission during white dwarf transit. In 1998 we obtained simultaneous BVRI photometry and Hα spectroscopy, with thorough phase coverage of the 12.5 hour orbital period. A binary star model was used with our light curve, radial velocity, and Hα data to refine stellar and orbital parameters. Combined absorption-emission profiles were generated by the model and fit to the observations, yielding a red star radius of 0.94⊙. Orbital inclination 78° is required with this size and other known parameters. The model includes three spots 1,000 K cooler than the surrounding photosphere. The variable Hα profile was modeled as a chromospheric region (essentially on the surface of the red star) centered at the substellar point. Additional emission seen outside our modeled profiles may be large co-rotating prominences that complicate the picture

    First-line erlotinib and fixed dose-rate gemcitabine for advanced pancreatic cancer

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    AIM: To investigate activity, toxicity, and prognostic factors for survival of erlotinib and fixed dose-rate gemcitabine (FDR-Gem) in advanced pancreatic cancer. METHODS: We designed a single-arm prospective, multicentre, open-label phase II study to evaluate the combination of erlotinib (100 mg/d, orally) and weekly FDR-Gem (1000 mg/m2, infused at 10 mg/m2per minute) in a population of previously untreated patients with locally advanced, inoperable, or metastatic pancreatic cancer. Primary endpoint was the rate of progression-free survival at 6 mo (PFS-6); secondary endpoints were overall response rate (ORR), response duration, tolerability, overall survival (OS), and clinical benefit. Treatment was not considered to be of further interest if the PFS-6 was < 20% (p0 = 20%), while a PFS-6 > 40% would be of considerable interest (p1 = 40%); with a 5% rejection error (α = 5%) and a power of 80%, 35 fully evaluable patients with metastatic disease were required to be enrolled in order to complete the study. Analysis of prognostic factors for survival was also carried out. RESULTS: From May 2007 to September 2009, 46 patients were enrolled (male/female: 25/21; median age: 64 years; median baseline carbohydrate antigen 19-9 (CA 19-9): 897 U/mL; locally advanced/metastatic disease: 5/41). PFS-6 and median PFS were 30.4% and 14 wk (95%CI: 10-19), respectively; 1-year and median OS were 20.2% and 26 wk (95%CI: 8-43). Five patients achieved an objective response (ORR: 10.9%, 95%CI: 1.9-19.9); disease control rate was 56.5% (95%CI: 42.2-70.8); clinical benefit rate was 43.5% (95%CI: 29.1-57.8). CA 19-9 serum levels were decreased by > 25% as compared to baseline in 14/23 evaluable patients (63.6%). Treatment was well-tolerated, with skin rash being the most powerful predictor of both longer PFS (P < 0.0001) and OS (P = 0.01) at multivariate analysis (median OS for patients with or without rash: 42 wk vs 15 wk, respectively, Log-rank P = 0.03). Additional predictors of better outcome were: CA 19-9 reduction, female sex (for PFS), and good performance status (for OS). CONCLUSION: Primary study endpoint was not met. However, skin rash strongly predicted erlotinib efficacy, suggesting that a pharmacodynamic-based strategy for patient selection deserves further investigation

    Soil-Cement Backfill for Nuclear Power Plant Foundations

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    Soil-cement backfills have been analyzed, designed and tested for the Alto Lazio Nuclear Power Plant in Italy. Extensive analyses were performed to evaluate the stability of and stresses in soil-cement foundation backfills. Soil-structure interaction was also analyzed. The minimum required cement content for foundation and general backfills was established and verified by means of laboratory and field tests. Foundation backfills were designed for two major buildings of the plant
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