The aim of this study was to evaluate the feasibility of microscopic endoscopic assisted suprameatal tubercle drilling with a retrosigmoid approach and it focuses on the anatomic structures ...identified with the endoscope. The advantages of the 30 degrees optic view are also described.
Fifty dry temporal bones were studied in order to estimate the variability of the prominence of the suprameatal tubercle. Eight fresh cadaveric specimens were prepared for a retrosigmoid approach to allow for microscopic endoscopic assisted suprameatal tubercle drilling. The increase in trigeminal exposure and neurovascular structures visualization with the endoscope, using 0 degrees and 30 degrees optics were then evaluated.
Three major types of the suprameatal tubercle were found: 1) a large size tubercle (> 6 mm, 9/50 cases); 2) a medium size tubercle (3-6 mm, 37/50 cases); and 3) an almost absent suprameatal tubercle (< 3 mm, 4/50 cases). Microscopic endoscopic assisted suprameatal tubercle drilling with opening of the Meckel's Cave was found to be technically feasible in all cases. The increase in trigeminal nerve exposition was of 9 mm on average. Endoscopic exploration with 0 degrees and 30 degrees optics made possible the identification of all neurovascular structures in the area.
Microscopic endoscopic assisted suprameatal tubercle drilling is a feasible procedure that allows the identification of all neurovascular structures in the cerebellopontine angle and petrous apex region. The opening of Meckel's Cave may be particularly useful for lesions located in the cerebellopontine angle having a minor component that extends anteriorly and laterally in the middle cranial fossa.
•We present the first CCD filtered light curves of the W UMa system NSVS 1557555.•The analysis, using the W-D code, shows that it is a W-Subtype W UMa system.•The light curves show asymmetries at the ...maxima with the inverse O’Connell effect.•Solution was possible with an hot spotted region and a large amount of third light.•The absolute dimensions of the system are estimated.
We present the first CCD sets of complete light curves for the W Ursae Majoris system NSVS 1557555.
The observations were performed in the B, V and Ic bands using the 0.25 m telescope of the Stazione Astronomica Betelgeuse Northern Italy, during 8 nights in October and November 2016.
Based on our new eleven Time of Minima (ToM), and two recent ones found in bibliography, the short orbital period of the system is confirmed and revised to P = 0.2725163 days .
A reasonable fit of the synthetic light curves of the data indicate that NSVS 1557555 is a late-type (K1+K3) shallow contact binary system of W-Subtype of the W Ursae Majoris systems, with a mass ratio of q = 1.8, a degree of contact factor f = 12.5%, a temperature difference between the components of 240K and inclination i = 85°.
The light curves show asymmetries at the maxima with the maximum at phase 0.75 higher the other one (inverse O’Connell effect).
To explain the light asymmetries we used a model that involves an hot spotted region on the surface of the cooler star.
The definitive solution is only possible with a large amount of third light (L3 = 0.58 in B Filter). It may come from a hot tertiary component.
The absolute dimensions of the system are estimated. From the logM-logL diagram it is seen that both components of NSVS 1557555 follow the general pattern of the W subtype W Ursae Majoris systems.
The orbital angular momentum is compared with those of other W UMa type binaries and is normal.
•We present new CCD filtered light curves of the W UMa system VSX J045718.3+405643.•The analysis, using the W-D code, shows that it is a A-subtype W UMa system.•The system is an low mass-ratio and ...has a moderate fill-out factor.•The absolute dimensions of the system are estimated and discussed.
We present the results of our investigation of the geometrical parameters of the W UMa-type binary system VSX J045718.3+405643 (short name VSX J0457) based on new CCD B, V and Ic light curves.
Our observations were carried out during six nights in November and December 2016 using the 0.25 m telescope of the Stazione Astronomica Betelgeuse in Magnago, Northern Italy.
Six new times of minima and light elements have been determined and the observed light curves were analysed using the Wilson–Devinney code.
The output model reveals that the system is a contact binary of A-Subtype of the W Ursae Majoris systems with a mass ratio of q ∼ 0.26 and a degree of contact factor f ∼ 32%.
The primary component is hotter than the secondary by 95 K, this suggests us that the system is under thermal contact.
The high orbital inclination (i = 82°.2) implies that VSX J0457 is a total eclipsing binary system and the photometric parameters here obtained are quite reliable.
The absolute physical parameters of the two components in VSX J0457 are estimated.
Based on these estimated parameters the evolutionary state of the system components is investigated and discussed.
Combining our photometric solution with the 3-D correlation obtained for contact binaries by Gazeas (2009) we derive the masses and radii of the components of this eclipsing system as M1 = 1.44M⊙, M2 = 0.38M⊙, R1 = 1.55R⊙ and R2 = 0.87R⊙.
The distance to VSX J0457 was calculated as 147 pc from this analysis, taking into account interstellar extinction.
We present the results of our study of the W Ursae Majoris eclipsing binary systems (EW) TYC 2402-643-1, TYC 2703-1235-1 and TYC 2913-2145-1 based on CCD observations obtained using Sloan g’ and i' ...filters. The light curves were analysed using the latest version of the Wilson-Devinney code, and the obtained data were used to estimate the physical parameters of the systems. TYC 2402-643-1 and TYC 2913-2145-1, having mass ratio < 0.25, can be classified as Extreme Mass Ratio Binary (EMRBs) systems and belong to the A-subtype class of the EW. The third one, TYC 2703-1235-1, having mass ratio q about 3 (1/q = 0.33) belongs to W-subtype class of the EW. The absolute dimensions of the primaries and secondaries were estimated and investigated using different evolutionary diagrams. The parameters of the progenitors of the components of the systems were calculated and the results are consistent with the determination of the subtypes.
The pathogenesis of moyamoya disease (MMD) is still unknown. The detection of inflammatory molecules such as cytokines, chemokines and growth factors in MMD patients' biological fluids supports the ...hypothesis that an abnormal angiogenesis is implicated in MMD pathogenesis. However, it is unclear whether these anomalies are the consequences of the disease or rather causal factors as well as these mechanisms remain insufficient to explain the pathophysiology of MMD. The presence of a family history in about 9-15% of Asian patients, the highly variable incidence rate between different ethnic and sex groups and the age of onset support the role of genetic factors in MMD pathogenesis. However, although some genetic loci have been associated with MMD, few of them have been replicated in independent series. Recently, RNF213 gene was shown to be strongly associated with MMD occurrence with a founder effect in East Asian patients. However, the mechanisms leading from RNF213 mutations to MMD clinical features are still unknown.
The research on pathogenic mechanism of MMD is in its infancy. MMD is probably a complex and heterogeneous disorder, including different phenotypes and genotypes, in which more than a single factor is implicated.
Since the diagnosis of MMD is rapidly increasing worldwide, the development of more efficient stratifying risk systems, including both clinical but also biological drivers became imperative to improve our ability of predict prognosis and to develop mechanism-tailored interventions.
A new CCD (V) light curve is presented for the semi-detached binary system FU Ara. The light curve, obtained in 2007, is the first one since the last 50 years. With our data we were able to determine ...six new times of minimum light and refined the period of the system to 0.8645049 days. A Wilson-Devinney analysis leads to a solution of a semi-detached configuration, composed of a main-sequence primary component of spectral type F5, fractionally smaller than its Roche lobe, and an evolved secondary component of spectral type K1 which fills its Roche lobe, and which is overluminous and oversized as compared with the main-sequence. The two components of FU Ara differ considerably in effective temperature. It is classified as an FO Virginis type of near-contact binary system. Assuming a reasonable value for the mass of the primary component, an estimate of the absolute elements of FU Ara has been made, on the assumption that the primary has a mass corresponding to its spectral type according to Svechnikov & Taidakova.
We present B, V, Rc and Ic light curves of four contact binary systems and one semi-detached system. New observations confirm and revise the short-period (0.22–0.25d) of the systems and that all the ...couple of stars belong to the spectral type K. In J105924 and J164349 a third light was found while the shape of the light curves of four systems (excluding J105924) suggest the presence of inhomogeneities on the surface of one component which confirms that the systems are active. Also they are observed at low orbital inclination i∈ (41°, 62°). Temperature differences range is ΔT∈(4,640)K and mass ratios q∈(0.20, 0.75). Absolute parameters are estimated using statistical diagrams. Systems follow the general pattern of the relative subtype of W Ursae Majoris systems. The sum of the component masses of four systems is below the mass limit of 1.0 – 1.2M☉ assumed for the known contact binary stars, this tells us that they belong to the class low mass contact binaries.
The results of our study of the eclipsing binary systems AF LMi, CzeV188 and CRTS J073333.0+302556 based on new CCD B, V, RC, IC complete light curves, are here presented. The short periods of these ...systems are confirmed and revised. The light curves were modeled using the latest version of the WilsonDevinney code and, as a result, we found that AF LMi (G3+G9) and CzeV188 (K0+K1) are W UMa-type contact binary systems belonging to the W subclass, showing a shallow degree of fill-out with components in good thermal contact. CRTS J073333.0+302556 is a detached binary system composed by a late dwarf (K8) and an M6 dwarf spectral type components. The asymmetries of the light curves were accounted for with a spot on the surface of one of the component. The absolute elements of the three objects were estimated.
The first analysis of the light curves of contact binaries ROTSE J135349.8+305205 (CB1) and 1SWASP J150957.5-115308 (CB2) using the Wilson-Devinney code is presented. Both binary systems are of the ...A-subtype with a shallow fill-out (20.8% and 15.8% respectively) and a difference in temperatures between the components of < 200 K. A mass-ratio of 0.302 is found for CB1, while for CB2 the interesting value of 0.904 is found. The short periods, 0.246 d for CB1 and 0.229 d for CB2, and their spectral type K suggests that these systems are near the shortest period limit. The absolute elements are estimated using GAIA parallaxes. CB2 is found to be at the beginning of its evolution, while CB1 will approach the final evolutionary stage. The sum of the component masses of CB1 is 0.813 M☉, below the mass limit of 1.0 − 1.2 M☉ assumed for the known contact binary stars.
We provide a detailed insight on the design of InGaAs/InP single-photon avalanche diode (SPAD) for 1.55- μm photon detection. In order to lower SPAD noise the dark count rate (DCR) without lowering ...photon detection efficiency (PDE) or increasing afterpulsing, it is important to optimize detector vertical layer structure and diffusion profiles. We present simulations of SPAD structures with different models, including custom ones. We discuss the influences of multiplication region thickness and doping, absorption region thickness, and electric-field distribution on SPAD performance. Multiplication region thickness strongly affects tunneling generation, whereas a thicker absorption region gives higher absorption efficiency but reduces trigger efficiency. Their optimal values depend on InP and InGaAs material quality and on device operating conditions. We show how electric field within InGaAs must be chosen as a tradeoff between heterobarrier transit efficiency and carrier generation.
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