1,723,279 research outputs found
Modelling the magnetic activity and filtering radial velocity curves of young Suns : the weak-line T Tauri star LkCa 4
No full textSGG acknowledges support from the Science & Technology Facilities Council (STFC) via an Ernest Rutherford Fellowship [ST/J003255/1]. SHPA acknowledges financial support from CNPq, CAPES and Fapemig.We report results of a spectropolarimetric and photometric monitoring of the weak-line T Tauri star LkCa 4 within the Magnetic Topologies of Young Stars and the Survival of close-in giant Exoplanets (MaTYSSE) programme, involving ESPaDOnS at the Canada–France–Hawaii Telescope. Despite an age of only 2 Myr and a similarity with prototypical classical T Tauri stars, LkCa 4 shows no evidence for accretion and probes an interesting transition stage for star and planet formation. Large profile distortions and Zeeman signatures are detected in the unpolarized and circularly polarized lines of LkCa 4 using Least-Squares Deconvolution (LSD), indicating the presence of brightness inhomogeneities and magnetic fields at the surface of LkCa 4. Using tomographic imaging, we reconstruct brightness and magnetic maps of LkCa 4 from sets of unpolarized and circularly polarized LSD profiles. The large-scale field is strong and mainly axisymmetric, featuring a ≃2 kG poloidal component and a ≃1 kG toroidal component encircling the star at equatorial latitudes – the latter making LkCa 4 markedly different from classical T Tauri stars of similar mass and age. The brightness map includes a dark spot overlapping the magnetic pole and a bright region at mid-latitudes – providing a good match to the contemporaneous photometry. We also find that differential rotation at the surface of LkCa 4 is small, typically ≃5.5 times weaker than that of the Sun, and compatible with solid-body rotation. Using our tomographic modelling, we are able to filter out the activity jitter in the radial velocity curve of LkCa 4 (of full amplitude 4.3 km s−1) down to an rms precision of 0.055 km s−1. Looking for hot Jupiters around young Sun-like stars thus appears feasible, even though we find no evidence for such planets around LkCa 4.Peer reviewe
Chao leng xuan liang hun he wu zhong de yi he jian xiang gan zi xuan dong li xue
No full textLi, Xiaoke = 超冷旋量混合物中的異核間相干自旋動力學 / 李小科.Thesis Ph.D. Chinese University of Hong Kong 2015.Includes bibliographical references (leaves 126-142).Abstracts also in Chinese.Title from PDF title page (viewed on 25, October, 2016).Li, Xiaoke = Chao leng xuan liang hun he wu zhong de yi he jian xiang gan zi xuan dong li xue / Li Xiaoke
Yi He Yuan (Summer Palace Parkı) koruma çalışmalarının peyzaj tasarımı açısından değerlendirilmesi
No full textBu araştırma, Pekin’deki Yi He Yuan (Yaz Sarayı Parkı)’nın kuruluşu, tarihi gelişiminin incelenmesi, bugünkü durumunun irdelenmesi ve peyzaj tasarımı açısından değerlendirilmesi ile Çin park ve bahçelerinin tasarım prensiplerinin belirlenmesine yönelik bir çalışmadır. Bu amaçla çalışmada, Çin’deki kent parklarından ve dünyadaki kent parklarından örnekler alınmıştır. Bu kapsamda, öncelikle park (yeşil alan) kavramı, işlevleri ve açık-yeşil alan standartları incelenmiş, ayrıca araştırma alanları tanımlanmış ve ilgili fotoğraflar verilmiştir. Bu çalışma sonucunda, kent parklarının tanımlanması ve kentlerin gelişime ve refahındaki sürdürülebilir yönetim modeli kapsamında stratejik planlama, geliştirme çalışmalarının yürütülmesinin gerekliği belirlenmiştir. Bu süreçte Çin park-bahçe felsefesi ve mimarisi yansıtılmıştır. Abstract This research covers the foundation, historical development and current state of the Yi He Yuan (Summer Palace) in Bei Jing. Yi He Yuan has been evaluated in terms of landscape design and the design prenciples of Chinese parks and gardens have been identified. Hence, some examples of urban parks from around the world and China have been examined. In this context, the concept of park (gren space) its functions and standards of urban green spaces have been searched. The research area has been defined and related photos have been taken. As a result of the study, the importance of strategic planning and development Works has been identified in terms of the definition of urban parks and sustainable management model for the development of citie. In this process, the philosophy and architecture of chinese parks and gardens have been reflected
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
JCB886240 Supplemetal Material - Supplemental material for High spatiotemporal vessel-specific hemodynamic mapping with multi-echo single-vessel fMRI
No full textSupplemental material, JCB886240 Supplemetal Material for High spatiotemporal vessel-specific hemodynamic mapping with multi-echo single-vessel fMRI by Yi He, Maosen Wang and Xin Yu in Journal of Cerebral Blood Flow & Metabolism</p
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