39 research outputs found

    A Holistic and Probabilistic Approach to the Ground-based and Spaceborne Data of HAT-P-19 System

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    We update the main physical and orbital properties of the transiting hot Saturn planet HAT-P-19 b, based on a global modelling of high-precision transit and occultation light curves, taken with ground-based and space telescopes, archive spectra and radial velocity measurements, brightness values from broadband photometry, and Gaia parallax. We collected 65 light curves by amateur and professional observers, measured mid-transit times, analyzed their differences from calculated transit timings based on reference ephemeris information, which we update as a result. We haven’t found any periodicity in the residuals of a linear trend, which we attribute to the accumulation of uncertainties in the reference mid-transit time and the orbital period. We comment on the scenarios describing the formation and migration of this hot-Saturn type exoplanet with a bloated atmosphere yet a small core, although it is orbiting a metal-rich ([Fe/H] = 0.24 dex) host star. Finally, we review the planetary mass-radius, the orbital period-radius and density, and the stellar metallicity-core mass diagrams, based on the parameters we derive for HAT-P-19 b and those of the other seventy transiting Saturn-mass planets from the NASA Exoplanet Archive

    Physical Parameters of Some Close Binaries: ET Boo, V1123 Tau, V1191 Cyg, V1073 Cyg and V357 Peg

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    With the aim of providing new and up-to-date absolute parameters of some close binary systems, new BVR CCD photometry was carried out at the Ankara University Observatory (AUG) for five eclipsing binaries, ET Boo, V1123 Tau, V1191 Cyg, V1073 Cyg and V357 Peg between April, 2007 and October, 2008. In this paper, we present the orbital solutions for these systems obtained by simultaneous light and radial velocity curve analyses. Extensive orbital solution and absolute parameters for ET Boo system were given for the first time through this study. According to the analyses, ET Boo is a detached binary while the parameters of four remaining systems are consistent with the nature of contact binaries. The evolutionary status of the components of these systems are also discussed by referring to their absolute parameters found in this study.Comment: this accepted paper will be published in New Astronom

    River water quality assessment using environmentric techniques : case study of Jakara River Basin.

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    akara River Basin has been extensively studied to assess the overall water quality and to identify the major variables responsible for water quality variations in the basin. A total of 27 sampling points were selected in the riverine network of the Upper Jakara River Basin. Water samples were collected in triplicate and analyzed for physicochemical variables. Pearson product-moment correlation analysis was conducted to evaluate the relationship of water quality parameters and revealed a significant relationship between salinity, conductivity with dissolved solids (DS) and 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), and nitrogen in form of ammonia (NH4). Partial correlation analysis (r p) results showed that there is a strong relationship between salinity and turbidity (r p = 0.930, p = 0.001) and BOD5 and COD (r p = 0.839, p = 0.001) controlling for the linear effects of conductivity and NH4, respectively. Principal component analysis and or factor analysis was used to investigate the origin of each water quality parameter in the Jakara Basin and identified three major factors explaining 68.11 % of the total variance in water quality. The major variations are related to anthropogenic activities (irrigation agricultural, construction activities, clearing of land, and domestic waste disposal) and natural processes (erosion of river bank and runoff). Discriminant analysis (DA) was applied on the dataset to maximize the similarities between group relative to within-group variance of the parameters. DA provided better results with great discriminatory ability using eight variables (DO, BOD5, COD, SS, NH4, conductivity, salinity, and DS) as the most statistically significantly responsible for surface water quality variation in the area. The present study, however, makes several noteworthy contributions to the existing knowledge on the spatial variations of surface water quality and is believed to serve as a baseline data for further studies. Future research should therefore concentrate on the investigation of temporal variations of water quality in the basin

    Modeling the changing spot features of SW Lacertae: A three year study

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    In the present study, the activity of the eclipsing binary of the W UMa-type system SW Lac is examined by analysing the new BV photoelectric observations obtained in 2001, 2002 and 2003 at the Ankara University Observatory. During this period, the seasonal light curves show significant differences and asymmetries. A simultaneous analysis of the light curves is made using Djurašević's inverse-problem method. To explain the light-curve asymmetries and the different maximum light levels in the seasonal light curves we used a Roche model that involved regions containing spots on the components. The analysis shows that SW Lac is in an overcontact configuration with a relatively high degree of overcontact foverf_{\rm over} \sim 31%. The Roche model with spotted areas on the more massive and cooler component yields a good fit of the observations for the whole set of the seasonal light curves, without any changes of the basic system parameters. This indicates that the complex nature of the light-curve variations during the examined period can be explained by the changes of spotted areas on the cooler component, which cover a significant part of the stellar surface

    A photometric study of NN Virginis

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    Photoelectric BV light curves of the recently discovered eclipsing binary NN Vir were studied for the first time to derive the physical parameters of the system. The light curves were obtained at the Ankara University Observatory during three nights in May, 2002. The solutions made by using Djurasevic's inverse problem method describe the NN Vir system as a high overcontact configuration (fover58%f_{\rm over} \sim 58\%) with a relatively small temperature differences between the components (ΔT=ThTc160\Delta T=T_{\rm h}-T_{\rm c}\sim 160 K). These solutions suggest a significant mass and energy transfer from the more massive primary onto the less massive secondary. The hot area on the less massive star, near the neck region, can be taken as a consequence of this mass and energy exchange between the components through the connecting neck of the common envelope

    Comparison of diagnostic values of procalcitonin, C-reactive protein and blood neutrophil/lymphocyte ratio levels in predicting bacterial infection in hospitalized patients with acute exacerbations of COPD [Vergleich der diagnostischen Wertigkeit von Procalcitonin, C-reaktivem Protein und vom Neutrophilen/Lymphozyten Quotienten bei der Vorhersage von bakteriellen Infekten bei hospitalisierten Patienten mit akuter Exazerbation einer chronisch obstruktiven Lungenerkrankung]

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    Background: Viral or bacterial upper respiratory infections are the most common cause of acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Based on available data, no reliable parameter has been presented to distinguish between bacterial and nonbacterial exacerbations. Therefore, we compared the diagnostic value of procalcitonin (PCT) level, which is a newer marker for predicting bacterial infections in patients with AECOPD, to routine parameters such as C-reactive protein (CRP) levels and the neutrophil/lymphocyte (N/L) ratio. Methods: This study included all consecutive patients who were admitted for a diagnosis of AECOPD between January 1 and March 31, 2014. PCT, CRP, and the N/L ratio were assessed in addition to cultures from tracheal aspirates or sputum on the first day of admission. Patients with a pneumonic infiltration on chest radiographs, or an extrapulmonary infection focus, or whose blood samples were not obtained for PCT and/or CRP at the same time as sputum culture were excluded from the study. Results: A total of 77 patients were included with a mean age of 71.7 ± 9.5 years. Bacteria were isolated in 37.4 % of the patients. Mean PCT levels were significantly higher in patients with positive sputum cultures than in patients with negative sputum cultures. The cut-off values for PCT, CRP, and the N/L ratio for predicting a bacterial infection were 0.40 ng/mL, 91.50 mg/L, and 11.5, respectively; sensitivity was 61, 54, and 61 % respectively; specificity was 67, 52, and 58 %, respectively; and the area under the curve (AUC) values were 0.64, 0.52, and 0.58, respectively. The AUC value of PCT was significantly better for predicting bacterial infection compared with the CRP level or the N/L ratio (p = 0.042). Conclusion: PCT was better than CRP and the N/L ratio for predicting a bacterial infection in hospitalized patients with AECOPD. However, we find PCT not so reliable in predicting bacterial infection in AECOPD due to sensitivity and specificity of less than 80 % and a low AUC value. © 2014, Springer-Verlag Wien

    Evaluating the efficiency of long term oxygen therapy and mortality in chronic obstructive pulmonary disease [Kronik obstrüktif akciğer hastalığında uzun süreli oksijen tedavisi etkinliğinin ve mortalitenin değerlendirilmesi]

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    It has been shown that Long Term Oxygen Therapy (LTOT) improves polycythemia secondary to hypoxemia and right heart failure, decreases pulmonary hypertension, improves quality of life and increases life expectancy in COPD patients. In our study we aimed to evaluate clinical data, mortality, patient's adherence and efciency of the therapy in COPD patients receiving LTOT. Mean age was 70.5%±9.7 and 57% of the participiants were male. It was shown that one year hospital admission count after LTOT (0.56±0.79) was decreased according to one year hospital admission count before LTOT (1.14±1.64). When arterial blood gas values after LTOT compared to the values at the time prescription PaO2 was increased (47.9±4, 53.4±9) and PaCO2 was decreased (56.1±11, 50.5±11). Although there was no signifcant diference in pulmonary artery pressure after LTOT, a signifcant increase was determined in hematocrit (38.37±6, 40.14±6). 41.1% of the patients had at least once device maintanence, and after LTOT only 38.4% had a clinical control due to COPD. The most common reason for irregular use was lack of necessity. Mean daily oxygen usage was 13.88±4.35 hours/day and 68.8% of the patients were using 15 hours or more. Mean follow-up of the patients were 17.85±14.53 (1-55) months and mortality rate in this period was 67%. Mortality was higher in LTOT with 15hours/day or more compared to less than 15 hours (respectively 54.6%, 12.5%). In conclusion, all patients with an indication for LTOT should be followed by national registry system and monitored in terms of technical services. Patients adherence and routine controls should be provided. Key words: COPD, mortality, concentrator, oxygen, LTOT © 2015, TIP ARASTIRMALARI DERNEGI. All rights reserved

    Association between continuous positive airway pressure and circulating omentin levels in patients with obstructive sleep apnoea

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    Purpose: Inflammation and oxidative stress play important roles in the pathogenesis of obstructive sleep apnoea syndrome (OSAS). Omentin is expressed in visceral adipose tissue and is associated with the inflammatory response. The aim of this study was to assess the relationship between OSAS and omentin based on a comparison of its serum levels at baseline and after 3 months of continuous positive airway pressure (CPAP) therapy. Methods: Ninety-six newly diagnosed OSAS patients and 31 non-apnoeic controls were enrolled in this study. Blood samples were obtained in the morning after polysomnography. Within the OSAS group, 30 patients were started on CPAP therapy and then reassessed clinically, including a blood test for serum omentin and other biochemical analysis, at 3 months. Results: Serum omentin levels were significantly lower in the OSAS group than in the control group (27.7 ± 7.6 and 42.5 ± 5.2 ng/mL, P < 0.001). In the subgroup analysis, omentin concentrations were significantly lower in patients with severe OSAS than in those with mild/moderate OSAS (P < 0.001). Circulating omentin levels were significantly correlated with the apnoea–hypopnoea index (AHI), mean SaO2, oxygen desaturation index, and serum C-reactive protein levels. Treatment with CPAP resulted in a significant increase in circulating omentin levels after 3 months, from 22.7 ± 1.4 to 41.2 ± 3.3 ng/mL (P < 0.001). Conclusions: OSAS is associated with low serum omentin levels, and these levels can be reversed by effective CPAP treatment. © 2016, Springer-Verlag Berlin Heidelberg
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