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2021 ◽  
Vol 2145 (1) ◽  
pp. 012005
Author(s):  
N Lamlert ◽  
W Maithong

Abstract V781 Tau is one of W UMa eclipsing binary systems whose orbital period is 0.34 days. The 0.7-meter telescope with CCD photometric system in B and V filters was conducted at the Regional Observatory for the Public, Chachoengsao, Thailand during December 2018, UT. The Wilson-Devinney Technique was used for calculating the physical properties of V781 Tau. The results showed the inclination of their orbital is 66.140°±0.14. The effective temperature of the primary and secondary star is 6,060 and 5,881 K, respectively and the degree of contact is 4.38 %


2021 ◽  
Author(s):  
◽  
Timothy Stuart Banks

<p>This thesis describes the collection, reduction, and analysis of Charge Coupled Detector (CCD) images of star clusters. The objects studied are primarily in the Large Magellanic Cloud (LMC), a nearby galaxy. The study of these groupings can provide information such as the initial dynamic state of Globular Clusters, the heavy-clement enrichment rate of the LMC, the distribution of masses that stars form with, and the validity of given stellar evolution models. The majority of the observations were collected at Mount John University Observatory (NZ). Procedures for the collection and transfer of the data are described, along with an overview of the analysis facility and CCDs. Statistical moment-based ellipse fitting was applied to the observations, confirming that trends are evident in the position angles and ellipticities of the clusters, as had been reported in the literature. Artificial images of clusters with known parameters were generated and subjected to the same analysis techniques, revealing apparent trends caused by stochastic processes. Caution should therefore be exercised in the interpretation of observational trends in the structure of young LMC clusters. Isochrones were used to date the 19 clusters. The resulting ages are in good agreement with the literature, as are results from profile modeling. There is no evidence for tidal truncation of the young clusters. Observations were made of two LMC and two Galactic star clusters in a test of imaging clusters with the Vilnius photometric system and a CCD. The colour-magnitude diagrams, distances and interstellar reddenings of the clusters were derived and found to be in agreement with the literature. This is the first time that the standard Vilnius filter set has been used with a CCD. Use of the system for direct imaging of star clusters appears promising. Johnson BV CCD observations were made of the young LMC cluster NGC 2214 and a nearby field using the Anglo-Australian Telescope. It has been suggested in the literature that this elliptical cluster is actually two clusters in the process of merging. No evidence was found from profile fitting or the colour-magnitude diagrams to support this contention. Completeness factors were estimated for the CCD frames. These values were used in conjunction with luminosity functions to estimate the Initial Mass Function (IMF) for NGC 2214. A power-law M-(1+x) was assumed for the IMF (where M is stellar mass relative to that of the Sun Mo), with a good fit being found for x = 1.01 plus-minus 0.09. There is some indication that the low mass end (less than or equal to 3oMo) has a smaller gradient than the high mass end of the derived IMF. The value of x is in reasonable agreement with literature values for other Magellanic IMFs, and not substantially different from the poorly determined Galactic IMFs, suggesting the possibility of a 'universal' IMF over the Magellanic Clouds and our Galaxy in the mass range tilde 1 to tilde 10 Mo.</p>


2021 ◽  
Author(s):  
◽  
Murray Charles Forbes

<p>The Vilnius Standard Photometric System is said to have several advantages over other photometric systems; reduction procedures free of systematic errors, a homogeneous set of standard stars, accurate dereddening, spectral classification and calibration of physical parameters for normal stars, and a good detection rate of abnormal stars. To investigate these, two southern, open star clusters (Omicron Velorum and Kappa Crucis) have been measured in the Vilnius system. The observations were used to derive astrophysical parameters such as age ((45 plus-minus l5)x106 and (10 plus-minus 3)x10 6 years respectively), composition (both solar metallicity), distance to the clusters (m-M = 5m.94 plus-minus 0.02 and 12m.18 plus-minus 0.05), interstellar reddening along our light of sight to the clusters (Ey-v = 0m.00 plus-minus 0.02 and 0m.31 plus-minus 0.09), and cluster membership probabilities for the individual stars. These compared favorably with the consensus of similar analyses made by observers using other photometric systems, with one exception being the distance to Kappa Crucis ( = 11m.59). As no stars further south than declination -26 degrees have been measured in the (original) Vilnius System, it was necessary to calibrate the local system to the standard system by measuring equatorial stars common to both. To alleviate this problem in the future, suitable southern stars were measured to form a southern standard system. Initially bright stars evenly spread across the sky were calibrated - this will ensure any future observing programme will have nearby standards. The next phase of the programme was to calibrate the E-region stars - this is a set of stars in common use as southern standards in other photometric systems. The final phase was to calibrate a sequence of stars near the south celestial pole - producing a set of stars so that the same standards can be observed at any time during the year. This southern standard system could not be completely established in the time available (it is approximately 50% finished), due to the larger than expected uncertainties in the measurements largely caused by the atmospheric effects of the Mount Pinatubo eruption.</p>


2021 ◽  
Author(s):  
◽  
Murray Charles Forbes

<p>The Vilnius Standard Photometric System is said to have several advantages over other photometric systems; reduction procedures free of systematic errors, a homogeneous set of standard stars, accurate dereddening, spectral classification and calibration of physical parameters for normal stars, and a good detection rate of abnormal stars. To investigate these, two southern, open star clusters (Omicron Velorum and Kappa Crucis) have been measured in the Vilnius system. The observations were used to derive astrophysical parameters such as age ((45 plus-minus l5)x106 and (10 plus-minus 3)x10 6 years respectively), composition (both solar metallicity), distance to the clusters (m-M = 5m.94 plus-minus 0.02 and 12m.18 plus-minus 0.05), interstellar reddening along our light of sight to the clusters (Ey-v = 0m.00 plus-minus 0.02 and 0m.31 plus-minus 0.09), and cluster membership probabilities for the individual stars. These compared favorably with the consensus of similar analyses made by observers using other photometric systems, with one exception being the distance to Kappa Crucis ( = 11m.59). As no stars further south than declination -26 degrees have been measured in the (original) Vilnius System, it was necessary to calibrate the local system to the standard system by measuring equatorial stars common to both. To alleviate this problem in the future, suitable southern stars were measured to form a southern standard system. Initially bright stars evenly spread across the sky were calibrated - this will ensure any future observing programme will have nearby standards. The next phase of the programme was to calibrate the E-region stars - this is a set of stars in common use as southern standards in other photometric systems. The final phase was to calibrate a sequence of stars near the south celestial pole - producing a set of stars so that the same standards can be observed at any time during the year. This southern standard system could not be completely established in the time available (it is approximately 50% finished), due to the larger than expected uncertainties in the measurements largely caused by the atmospheric effects of the Mount Pinatubo eruption.</p>


2021 ◽  
Author(s):  
◽  
Timothy Stuart Banks

<p>This thesis describes the collection, reduction, and analysis of Charge Coupled Detector (CCD) images of star clusters. The objects studied are primarily in the Large Magellanic Cloud (LMC), a nearby galaxy. The study of these groupings can provide information such as the initial dynamic state of Globular Clusters, the heavy-clement enrichment rate of the LMC, the distribution of masses that stars form with, and the validity of given stellar evolution models. The majority of the observations were collected at Mount John University Observatory (NZ). Procedures for the collection and transfer of the data are described, along with an overview of the analysis facility and CCDs. Statistical moment-based ellipse fitting was applied to the observations, confirming that trends are evident in the position angles and ellipticities of the clusters, as had been reported in the literature. Artificial images of clusters with known parameters were generated and subjected to the same analysis techniques, revealing apparent trends caused by stochastic processes. Caution should therefore be exercised in the interpretation of observational trends in the structure of young LMC clusters. Isochrones were used to date the 19 clusters. The resulting ages are in good agreement with the literature, as are results from profile modeling. There is no evidence for tidal truncation of the young clusters. Observations were made of two LMC and two Galactic star clusters in a test of imaging clusters with the Vilnius photometric system and a CCD. The colour-magnitude diagrams, distances and interstellar reddenings of the clusters were derived and found to be in agreement with the literature. This is the first time that the standard Vilnius filter set has been used with a CCD. Use of the system for direct imaging of star clusters appears promising. Johnson BV CCD observations were made of the young LMC cluster NGC 2214 and a nearby field using the Anglo-Australian Telescope. It has been suggested in the literature that this elliptical cluster is actually two clusters in the process of merging. No evidence was found from profile fitting or the colour-magnitude diagrams to support this contention. Completeness factors were estimated for the CCD frames. These values were used in conjunction with luminosity functions to estimate the Initial Mass Function (IMF) for NGC 2214. A power-law M-(1+x) was assumed for the IMF (where M is stellar mass relative to that of the Sun Mo), with a good fit being found for x = 1.01 plus-minus 0.09. There is some indication that the low mass end (less than or equal to 3oMo) has a smaller gradient than the high mass end of the derived IMF. The value of x is in reasonable agreement with literature values for other Magellanic IMFs, and not substantially different from the poorly determined Galactic IMFs, suggesting the possibility of a 'universal' IMF over the Magellanic Clouds and our Galaxy in the mass range tilde 1 to tilde 10 Mo.</p>


2021 ◽  
Vol 2091 (1) ◽  
pp. 012014
Author(s):  
K V Pozhar ◽  
M O Mikhailov ◽  
E A Polyakova ◽  
E L Litinskaia

Abstract The paper considers the method of diffuse reflectance spectroscopy for noninvasive glucose level measuring in biological tissues. It is proposed a portable implementation of the system, based on a laser diode with a wavelength of 1600 nm and a power of 30 mW, operating in a pulsed mode, as well as a set of NIR-photodiodes located around the laser. The measuring system has been tested on model solutions with diffuse reflectance from polystyrene and pigskin. In the course of measurements on fixed system, an error of ~17 mg/dl is observed, which can be reduced by improving miniature laser sources.


F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 719
Author(s):  
Marija Petrushevska ◽  
Dragica Zendelovska ◽  
Emilija Atanasovska ◽  
Aleksandar Eftimov ◽  
Katerina Spasovska

Introduction: COVID-19 can be worsened by hyper-production of cytokines accompanied by increased level of oxidative stress. The aim of this study was to investigate the correlation between a set of cytokines and the markers of the oxidative stress. Methods: The levels of cytokines IL-2, IL-4, IL-6, IL8, IL-10, VEGF, IFN-γ, TNF-α, IL-1α, MCP-1 and EGF were determined by using High Sensitivity Evidence Investigator™ Biochip Array technology. The oxidative stress parameters (d-ROM, PAT, OS index) were measured in serum on FRAS5 analytical photometric system. Results: IL-6, IL-8, IL-10, VEGF, MCP-1 and EGF were significantly higher (p<0.05) in the patients with severe COVID-19 with increased levels of IL-2, IFN-y, TNF-α and IL-1α. The d-ROM, OS index, and PAT were significantly higher (p<0.05) in severe COVID-19 patients. IL-6 demonstrated the strongest correlation with all of the markers of the oxidative stress, d-ROM (r=0.9725, p=0.0001), PAT (r=0.5000, p=0.0001) and OS index (r=0.9593, p=0.012). Similar behavior was evidenced between IFN-y and d-ROM (r=0.4006, p=0.0001), PAT (r=0.6030, p=0.0001) and OS index (r=0.4298, p=0.012). Conclusion: The oxidative stress markers show good correlation with the tested cytokines which can be measured at the beginning of the disease in a primary care setting to predict the course of COVID-19.


2021 ◽  
Author(s):  
Paul Eduardo David Soto Rodriguez ◽  
Morgane Valles ◽  
Agostino Romeo ◽  
Rafael Artuch ◽  
Samuel Sánchez

Phenylketonuria (PKU) is a metabolic disease resulting from a deficiency in the enzyme phenylalanine hydroxylase, increasing L-Phenylalanine (L-Phe) values in the blood and consequently in the brain. If untreated, PKU leads to neurological damage, which can be prevented by following a diet low in L-Phe. Thus, early detection of PKU in newborns is essential. The disease’s screening and monitoring are centralized in reference centers, which require specialized equipment. However, using these techniques, sample treatment is required before the analysis, and trained personnel must perform and interpret the results. In this work, we present an enzyme-based photometric strategy to measure blood L-Phe. An enzymatic mixture, selective for L-Phe, is immobilized on an UV transparent well, and the amount of consumed co-factor is monitored at 340 nm. Standard plasma and whole blood samples were chosen to pre-validate the sensor. The samples were spiked with an increasing amount of L-Phe, accurately discriminating between physiological and pathological L-Phe concentrations. The strategy can be easily extended to analyzing other samples, such as urine or sweat. The proposed photometric system allows to analyze up to 16 samples simultaneously within a matter of hours. The measurements are relatively fast, versatile, cost-effective, and easy to carry out.


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