•We present the first multi-color light curve analysis of the eclipsing binary star NSVS 2701634.•The orbital period variation are studied for the first time.•The system belong to the W-subtype W ...Ursae Majoris systems.•Its spectral type K makes interesting this study on NSVS 2701634.•Both the components of NSVS 2701634 follow the general pattern of the W-subtype systems in the logM-logL diagram.
We present the first CCD sets of complete light curves for the W Ursae Majoris W-type system NSVS 2701634. The observations were performed in the B, V and Ic bands using the 0.25 m telescope of the “Stazione Astronomica Betelgeuse” Italy, during 8 nights in April 2015.
From our observations we were able to confirm and revise the short-period (0.24 days) variation found by Shaw and collaborators in their online list (http://physast.uga.edu/~jss/nsvs/) of periodic variable stars found in the Northern Sky Variability Survey.
Using our 12 times of minimum light, the orbital period variations of NSVS 2701634 are studied for the first time. The general trend of the (O-C) curve reveals that its period is varying by a downward parabola that means that period is decreasing, this fact could be explained by a mass transfer between the components of the system.
The light curves were modelled using the Wilson–Devinney code and the elements obtained from this analysis are used to compute the physical parameters of the system in order to study its evolutionary status.
A reasonable fit of the synthetic light curves of the data indicated that NSVS 2701634 is an late-type (K3−K4+K6) contact binary system of W-Subtype of the W Ursae Majoris systems, with a mass ratio of q = 2.60, a degree of contact factor f = 15.3% and inclination i = 72°. The light curves show asymmetries at the maxima that are fitted adding an hot spot on the surface of the more massive star, known as inverse O’Connell effect.
From an estimation of the absolute dimensions of the system and from the logM-logL diagram, it is seen that both components of NSVS 2701634 follow the general pattern of the W subtype W Ursae Majoris systems.
To investigate the application of indocyanine green (ICG) videoangiography during microsurgery for central nervous system (CNS) tumors.
One hundred patients with CNS tumors who underwent ...microsurgical resection from December 2006 to December 2008 were retrospectively analyzed. The diagnosis was high grade glioma in 54 cases, low grade in 17 cases, meningioma in 14 cases, metastasis in 12 cases and hemangioblastoma in 3 cases. Overall, ICG was injected intraoperatively 194 times. The standard dose of 25mg of dye was injected intravenously and intravascular fluorescence from within the blood vessels was imaged through an ad hoc microscope with dedicated software (Pentero, Carl Zeiss Co., Oberkochen, Germany). Pre-resection and post-resection arterial, capillary and venous ICG videoangiographic phases were intraoperatively observed and recorded.
ICG videangiography allowed for a good evaluation of blood flow in the tumoral and peritumoral exposed vessels in all cases. No side effects due to ICG were observed.
ICG video-angiography is a significant method for monitoring blood flow in the exposed vessels during microsurgical removal of CNS tumors. Pre-resection videoangiography provides useful information on the tumoral circulation and the pathology-induced alteration in surrounding brain circulation. Post-resection examination allows for an immediate check of patency of those vessels that are closely related to the tumor mass and that the surgeon does not want to damage.
•CO2 diffusivity significantly decreased with increasing salt content (0–2.7% w/w).•CO2 diffusivity significantly increased with ripening time (2–8weeks).•CO2 diffusivity was found to be isotropic in ...relation to the cheese pressing axis.•CO2 diffusivity and solubility coefficient in semi-hard cheese were not related.
This study focuses on CO2 diffusivity, which is one of the most important factors impacting eye growth in semi-hard cheese, but yet has scarcely been investigated in literature. The effect of compositional and ripening parameters on experimental CO2 diffusivity in semi-hard cheese was studied. CO2 diffusivity in semi-hard cheese showed a complex relationship with temperature in the range 4–25°C, represented by a quadratic curve with the highest diffusivity at 13°C. Salt was found to impact CO2 diffusivity, with a decrease of about 60% for 0–2.7% w/w salt addition, which may be ascribed to viscosity increase of the cheese matrix and “salting in” effect of protein. CO2 diffusivity was found to increase with moisture content from 39% to 42% w/w, then it decreased from 42% to 48% w/w. Inevitable changes in protein content of the three cheese variants may be responsible for the complex behaviour observed.
We characterize three different quenching circuits for InGaAs/InP single-photon avalanche diodes (SPADs) operated in gated mode: i) a simple passive quenching circuit; ii) an active quenching ...circuit; and iii) a fast active quenching circuit. For each of these, we acquire the shape of the avalanche current, at different excess biases, by reconstructing the waveform of the photons emitted from the detector during an avalanche and we simultaneously measure the afterpulsing probability and the dependence of dark count rate on gate period (to estimate the maximum count rate). We prove that the avalanche charge reduction is in agreement with the reduction of afterpulsing probability, giving a four-time decrease in afterpulsing when employing the fast active quenching circuit compared to the simple passive quenching circuit.
CO2 is produced by many microorganisms present in cheese and it can affect cheese quality both during processing and storage. The knowledge of the extent of CO2 production by cheese microorganism ...(CO2 production rate coefficients) may be used to predict gas exchange in cheese/packaging systems, helping dairy industries in the right choice of the packaging (higher/lower gas permeability) and mastering of cheese ripening. However very few coefficients for CO2 production rate have been published and the ones assessed in vitro (not inside real food) may not well describe the activity of the microorganisms in situ. We have therefore developed a methodology for the in situ assessment of CO2 production rate and applied it to cheese with propionic acid fermentation. The proposed methodology is based on infra-red measurement of CO2 and it allows measuring its accumulation up to 1% with 0.001% resolution, while monitoring the level of oxygen. The method showed a good repeatability, with a low coefficient of variation within samples (6.6%) and between samples (8.4%) compared to 10–30% between samples found in literature. The method was compared with a gas chromatography based method, which is also described.
•A novel method for in situ assessment of CO2 production in cheese is proposed.•The infra-red based method is compared with a gas chromatography technique.•Variance of our method (8.4%) is lower compared to current methods (10–30%).•The proposed method was successfully applied to measure cheese fermentation.
•We present the first CCD observations of TYCHO 3836-0854-1 and TYCHO 4157-0683-1.•They are other two examples of deep low-mass ratio (DLMR) overcontact binary stars.•Both the systems may be possible ...progenitors of merging stars, like V1309 sco.•The absolute dimensions of the systems are estimated.
Here we present the first CCD multi-color B, V and Ic light curves of the eclipsing binary stars TYC 3836-0854-1 and TYC 4157-0683-1, the data were obtained in four nights in the year 2010 and three nights in the year 2012 for the first one and in four nights in the year 2010 for the second one. Based on our data the short orbital periods of the systems are confirmed and revised to P=0.4155590days for TYC 3836-0854-1 and P=0.3960676days for TYC 4157-0683-1. Our observations of TYC 3836-0854-1 show symmetric light curves in all passbands with brightness in both maxima at the same level, while the light curve of TYC 4157-0683-1 appear to exhibit the typical O’Connell effect, with Maximum I brighter than Maximum II. By analyzing simultaneously the complete light curves with the 2003 version of the Wilson–Devinney code (2005 revision), photometric solutions were determined. Both the systems shows a small difference between the components temperatures of ΔT=14K for TYC 3836-0854-1 and ΔT =149K for TYC 4157-0683-1. The orbital inclination is i=78°.6 and i=79°.7 respectively. The systems are found to be a high fill-out, extreme mass ratio overcontact binary with a mass ratio of q = 0.206 and a fill-out factor of f=59.2% for TYC 3836-0854-1 and q=0.150 and a fill-out factor of f=76.3% for TYC 4157-0683-1, suggesting that both the systems are in the late stage of overcontact evolution.
It is known that deep (f>50%), low-mass ratio (q<0.25) overcontact binary stars (DLMR) are a very important resource for understanding the phenomena of Blue Straggler/FK Com-type stars that is an unsolved problem in stellar astrophysics. One of the possible explanations for their formation is from the coalescence of W UMa-type overcontact binary systems. The absolute dimensions of both the systems are estimated from the logTeff - logL diagram and their dynamical evolution is inferred.
In this work, a compact set-up and three different methods to measure the Photo-Detection Efficiency (PDE) of Silicon Photomultipliers (SiPMs) and Single-Photon Avalanche Diodes (SPADs) are ...presented. The methods, based on either continuous or pulsed light illumination, are discussed in detail and compared in terms of measurement precision and time. For the SiPM, these methods have the feature of minimizing the effect of both the primary and correlated noise on the PDE estimation. The PDE of SiPMs (produced at FBK, Trento, Italy) was measured in a range from UV to NIR, obtaining similar results with all the methods. Furthermore, the advantages of measuring, when possible, the PDE of SPADs (of the same technology and with the same layout of a single SiPM cell) instead of larger devices are also discussed and a direct comparison between measurement results is shown. Using a SPAD, it is possible to reduce the measurement complexity and uncertainty since the correlated noise sources are reduced with respect to the SiPM case.
Abstract
In this work we will document the design and the performances of a SiPM-based photo-detector with a surface area of 100 cm
2
conceived to operate as a replacement for PMTs. The signals from ...94 SiPMs are summed up to produce an aggregated output that exhibits in liquid nitrogen a dark count rate (DCR) lower than 100 cps over the entire surface, a signal to noise ratio better than 13, and a timing resolution better than 5.5 ns. The module feeds about 360 mW at 5 V with a dynamic range in excess of 500 photo-electrons on a 100 Ω differential line. The unit can also operate at room temperature, at the cost of an increase of DCR to 10
8
cps.
CO
is produced by many microorganisms present in cheese and it can affect cheese quality both during processing and storage. The knowledge of the extent of CO
production by cheese microorganism (CO
...production rate coefficients) may be used to predict gas exchange in cheese/packaging systems, helping dairy industries in the right choice of the packaging (higher/lower gas permeability) and mastering of cheese ripening. However very few coefficients for CO
production rate have been published and the ones assessed in vitro (not inside real food) may not well describe the activity of the microorganisms in situ. We have therefore developed a methodology for the in situ assessment of CO
production rate and applied it to cheese with propionic acid fermentation. The proposed methodology is based on infra-red measurement of CO
and it allows measuring its accumulation up to 1% with 0.001% resolution, while monitoring the level of oxygen. The method showed a good repeatability, with a low coefficient of variation within samples (6.6%) and between samples (8.4%) compared to 10-30% between samples found in literature. The method was compared with a gas chromatography based method, which is also described.
Silicon Photomultipliers with cell-pitch ranging from 12 μm to 20 μm were tested against neutron irradiation at moderate fluences to study their performance for calorimetric applications. The ...photosensors were developed by FBK employing the RGB-HD technology. We performed irradiation tests up to 2×1011 n/cm2 (1 MeV eq.) at the INFN-LNL Irradiation Test facility. The SiPMs were characterized on-site (dark current and photoelectron response) during and after irradiations at different fluences. The irradiated SiPMs were installed in the ENUBET compact calorimetric modules and characterized with muons and electrons at the CERN East Area facility. The tests demonstrate that both the electromagnetic response and the sensitivity to minimum ionizing particles are retained after irradiation. Gain compensation can be achieved increasing the bias voltage well within the operation range of the SiPMs. The sensitivity to single photoelectrons is lost at ∼1010 n/cm2 due to the increase of the dark current.
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