Context. One-opposition near-Earth asteroids (NEAs) are growing in number, and they must be recovered to prevent loss and mismatch risk, and to improve their orbits, as they are likely to be too faint for detection in shallow surveys at future apparitions. Aims. We aimed to recover more than half of the one-opposition NEAs recommended for observations by the Minor Planet Center (MPC) using the Isaac Newton Telescope (INT) in soft-override mode and some fractions of available D-nights. During about 130 h in total between 2013 and 2016, we targeted 368 NEAs, among which 56 potentially hazardous asteroids (PHAs), observing 437 INT Wide Field Camera (WFC) fields and recovering 280 NEAs (76% of all targets). Methods. Engaging a core team of about ten students and amateurs, we used the THELI, Astrometrica, and the Find_Orb software to identify all moving objects using the blink and track-and-stack method for the faintest targets and plotting the positional uncertainty ellipse from NEODyS. Results. Most targets and recovered objects had apparent magnitudes centered around V ∼ 22.8 mag, with some becoming as faint as V ∼ 24 mag. One hundred and three objects (representing 28% of all targets) were recovered by EURONEAR alone by Aug. 2017. Orbital arcs were prolonged typically from a few weeks to a few years; our oldest recoveries reach 16 years. The O−C residuals for our 1854 NEA astrometric positions show that most measurements cluster closely around the origin. In addition to the recovered NEAs, 22 000 positions of about 3500 known minor planets and another 10 000 observations of about 1500 unknown objects (mostly main-belt objects) were promptly reported to the MPC by our team. Four new NEAs were discovered serendipitously in the analyzed fields and were promptly secured with the INT and other telescopes, while two more NEAs were lost due to extremely fast motion and lack of rapid follow-up time. They increase the counting to nine NEAs discovered by the EURONEAR in 2014 and 2015. Conclusions. Targeted projects to recover one-opposition NEAs are efficient in override access, especially using at least two-meter class and preferably larger field telescopes located in good sites, which appear even more efficient than the existing surveys.
Amaç: Bu çalışmada, Sigara Bırakma Polikliniğine başvuran hastalarda anksiyete duyarlılık düzeyleri ile nikotin bağımlılığı ile sigara bırakma sonuçları arasındaki ilişkiyi araştırmayı amaçladık. Yöntem: Bu retrospektif çalışma Ocak 2017-Temmuz 2017 tarihleri arasında sigara bırakma polikliniğine başvuran 286 hastayı içermektedir. Sosyo-demografik özellikler, sigara içme durumu, Nikotin Bağımlılığı için Fagerström Testi (FTDN) skorları, Beck Depresyon Envanteri (BDI) ile ölçülen depresyon skorları ve Beck Anksiyete Envanteri (BAI) ve Anksiyete Duyarlılığı İndeksi-3 (ASI) ölçeklerinin skorları hasta tıbbi dosyalarından geriye dönük olarak alındı. Tüm hastalar ile irtibata geçildi ve hastaların anlık sigara içme durumu kaydedildi. Bulgular: Katılımcıların % 19,5'i (n = 56) (izlemeye gelmeyenler dahil) sigarayı bırakmış ve sigarayı bırakma tarihinden en az altı ay sonra hala içmemektedirler. Ortalama anksiyete duyarlılığı skorları orta / yüksek nikotin bağımlı hastalarda hafif nikotin bağımlı hastalardan anlamlı derecede yüksekti (sırasıyla p = 0.001 ve p <0.001). Anksiyete duyarlılığı ve tüm alt ölçeklerinin ortalama puanları, mevcut sigara içicilerin sigara içenlere göre anlamlı derecede yüksekti (her biri için p <0.001). Sonuç: Anksiyete duyarlılığının sigara bırakma başarısında ciddi bir engel olabileceği belirlenmiştir. Bununla birlikte, kaygı duyarlılığı, yüksek nikotin bağımlılığı ile anlamlı şekilde ilişkilidir. Sigarayı bırakmayı planlayan hastaların ilk günlerinden kaygı duyarlılığı, kaygı ve depresyon düzeylerini değerlendirmek önemlidir. Yüksek kaygı duyarlılığına sahip sigara içicileri dikkatle izlenmeli ve bırakma oranlarını artırmak için kaygı hassasiyetlerini azaltmak için tedaviler uygulanmalıdır.
Abstract-In this article, the mixed potential integral equation is discretized using the Rao-WiltonGlisson basis functions in order to obtain a method of moments matrix equation for a source reconstruction problem. The weighting functions used in the setup of the moments equation are Dirac delta functions. The entries of the moments matrix are computed using a semi-analytical method which is applicable to any method of moments problem with point matching. The analytical calculation is made possible by employing a differentiation property of the scalar Green function and the properties of the mesh elements of the source plane. The semi-analytical method makes it easier to increase the accuracy of the moments matrix elements. The accuracy of the method is shown by comparing the results obtained using the semi-analytical method to those obtained by a fully numerical procedure.
We determine abundance ratios of 37 dwarf ellipticals (dEs) in the nearby Virgo cluster. This sample is representative of the early-type population of galaxies in the absolute magnitude range −19.0 < M r < −16.0. We analyse their absorption line-strength indices by means of index-index diagrams and scaling relations and use the stellar population models to interpret them. We present ages, metallicities, and abundance ratios obtained from these dEs within an aperture size of R e /8. We calculate [Na/Fe] from NaD, [Ca/Fe] from Ca4227, and [Mg/Fe] from Mgb. We find that [Na/Fe] is underabundant with respect to solar, whereas [Mg/Fe] is around solar. This is exactly opposite to what is found for giant ellipticals, but follows the trend with metallicity found previously for the Fornax dwarf NGC 1396. We discuss possible formation scenarios that can result in such elemental abundance patterns, and we speculate that dEs have disc-like star formation history (SFH) favouring them to originate from late-type dwarfs or small spirals. Na-yields appear to be very metal-dependent, in agreement with studies of giant ellipticals, probably due to the large dependence on the neutron-excess in stars. We conclude that dEs have undergone a considerable amount of chemical evolution, they are therefore not uniformly old, but have extended SFH, similar to many of the Local Group galaxies.
We perform a detailed study of the stellar populations in a sample of massive Fornax dwarf galaxies using a set of newly defined line indices.Using data from the Integral field spectroscopic data, we study abundance ratios of eight dEs with stellar mass ranging from 108 to 109.5 M⊙ in the Fornax cluster. We present the definitions of a new set of high-resolution Lick-style indices to be used for stellar population studies of unresolved small stellar systems. We identify 23 absorption features and continuum regions, mainly dominated by 12 elements (Na, Ca, Sc, Ti, V, Cr, Mn, Fe, Ni, Y, Ba and Nd) in the wavelength range 4700–5400 Å and characterise them as a function of age, metallicity and alpha element abundance ratios. We analyse eight dEs and interpret the line strengths, measured in our new high resolution system of indices, with the aid of stellar population models with high enough spectral resolution. We obtain abundance ratio proxies for a number of elements that have never been studied before for dwarf ellipticals outside the Local Group. These proxies represent relative deviations from predicted index-strengths of base stellar population models built-up following the abundance pattern of The Galaxy. The abundance proxy trend results are compared to abundance ratios from resolved stars in the Local Group, and indices from integrated light of larger early-type galaxies. We find that all our dwarfs show a pattern of abundance ratios consistent with the disk of the Milky Way, indicative of slow formation in comparison to their high mass counterparts.
Abstract-The modified Watson transform is applied to the Mie series for the electromagnetic wave transmitted into the double negative cylinder due to high frequency plane wave incidence The Debye series expansion is adapted to the transmission coefficients to reveal the transmission mechanism at high frequency. The first term of the Debye series is examined. Two kinds of geometrical shadow regions and two kinds of geometrically lit regions are shown to exist. The field formation mechanisms in these regions are indicated. Several differences between a double positive cylinder and a double negative cylinder are determined The field computations are performed in the geometrical shadow and the geometrically lit regions for the first term of the Debye series. The residue series and steepest descent computations are shown to be in good agreement with the Mie series computations.
Abstract-The Debye expansion integrals obtained by application of the Modified Watson Transformation and Debye series expansion to the Mie series for the high frequency plane wave transmitted into a double negative (DNG) cylinder are solved in the geometrically lit regions of the corresponding Debye series terms. The Debye series expansion is made up to the possible maximum term after which double ray field formation is first observed. Using the steepest descent method and the geometrical optics approximation, the role of the lower ray in the double-ray field formation is pointed out. For refractive indices satisfying |n| ≥ 10, it is shown that the maximum Debye series term index up to which simple single-ray tracing can be performed is bigger for a DNG cylinder than that for a DPS cylinder and the difference between the term indices increases as |n| increases.
Abstract-The modified Watson transform is applied to the Mie series expression of the electromagnetic field scattered by a high frequency plane wave incident on an infinitely long double negative cylinder. The Debye expansion is applied to the Mie series coefficients to obtain a physical insight into the scattering mechanisms and achieve an efficient approach for the computation of the scattered field. The first two terms of the Debye series are computed using the residue series in the geometrical shadow regions and using the steepest descent method in the geometrically lit regions. It is observed that the results obtained from the series and from the modified Watson transform are in good agreement. The angular boundaries for the geometrically lit and the geometrical shadow regions of the double negative cylinder corresponding to the first two terms of the Debye series are determined. These are compared with the corresponding angular boundaries for a double positive cylinder. It is observed that the spatial extent of the geometrical shadow of the double negative cylinder corresponding to the second term of the Debye series is very small compared to that of the double positive cylinder due to the negative refraction in the double negative cylinder when the magnitude of the refractive index n is greater than √ 2. 56Şen and Kuzuoǧlu
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.