1,354,186 research outputs found
Taxis of Artificial Swimmers in a Spatio-Temporally Modulated Activation Medium
No full textContrary to microbial taxis, where a tactic response to external stimuli
is controlled by complex chemical pathways acting like sensor-actuator
loops, taxis of artificial microswimmers is a purely stochastic effect
associated with a non-uniform activation of the particles'
self-propulsion. We study the tactic response of such swimmers in a
spatio-temporally modulated activating medium by means of both numerical
and analytical techniques. In the opposite limits of very fast and very
slow rotational particle dynamics, we obtain analytic approximations
that closely reproduce the numerical description. A swimmer drifts on
average either parallel or anti-parallel to the propagation direction of
the activating pulses, depending on their speed and width. The drift in
line with the pulses is solely determined by the finite persistence
length of the active Brownian motion performed by the swimmer, whereas
the drift in the opposite direction results from the combination of the
ballistic and diffusive properties of the swimmer's dynamics
Chemotaxis of artificial microswimmers in active density waves
No full textLiving microorganisms are capable of a tactic response to external
stimuli by swimming toward or away from the stimulus source; they do so
by adapting their tactic signal transduction pathways to the
environment. Their self-motility thus allows them to swim against a
traveling tactic wave, whereas a simple fore-rear asymmetry argument
would suggest the opposite. Their biomimetic counterpart, the artificial
microswimmers, also propel themselves by harvesting kinetic energy from
an active medium, but, in contrast, lack the adaptive capacity. Here we
investigate the transport of artificial swimmers subject to traveling
active waves and show, by means of analytical and numerical methods,
that self-propelled particles can actually diffuse in either direction
with respect to the wave, depending on its speed and waveform. Moreover,
chiral swimmers, which move along spiraling trajectories, may diffuse
preferably in a direction perpendicular to the active wave. Such a
variety of tactic responses is explained by the modulation of the
swimmer's diffusion inside traveling active pulses
Self-Polarizing Microswimmers in Active Density Waves
No full textAn artificial microswimmer drifts in response to spatio-temporal
modulations of an activating suspension medium. We consider two
competing mechanisms capable of influencing its tactic response: angular
fluctuations, which help it explore its surroundings and thus diffuse
faster toward more active regions, and self-polarization, a mechanism
inherent to self-propulsion, which tends to orient the swimmer's
velocity parallel or antiparallel to the local activation gradients. We
investigate, both numerically and analytically, the combined action of
such two mechanisms. By determining their relative magnitude, we
characterize the selective transport of artificial microswimmers in
inhomogeneous activating media
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
No full text“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
No full textWe 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
No full textWe 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
Author, publisher and bookseller : a tripartite synergy in Nigerian book industry
No full textThis work is about the roles of Author, Publisher and Bookseller in Book development in
Nigeria. The paper started by delving into the history of Book Publishing in Nigeria after
which it proceeded by defining who an author, a publisher, and a bookseller is and
expatiated on the indispensable roles of these key actors in Nigerian Book Industry and in
the emerging Information Society. Furthermore, the various constraints to book
development were identified while the paper advised on how the Book Industry can be
further promoted in Nigeria. However, the paper concluded and made recommendations
on how the Book sector can help in enhancing scholarship in the country
The Thursday Murder Club: Launching a megabrand author - a publishing case study
No full textIn 2020, the Christmas book charts in the UK made headlines: Barack Obama’s eagerly awaited autobiography, The Promised Land, was beaten to the top spot by The Thursday Murder Club by Richard Osman, a debut cosy crime novel set in a retirement village. Not only did Osman’s book beat the former US president’s expected bestseller, it also broke records, becoming the fastest-selling debut crime novel of all time. Although Osman has a certain level of fame in the UK from his TV appearances on shows such as Pointless, his celebrity status does not entirely explain the novel’s huge sales. This article tracks the acquisition, publication, and promotion journey of The Thursday Murder Club in order to understand the industry and cultural context of its success and to interrogate the role of celebrity in the creation of author brands. The findings suggest that the unexpected scale of the success of the book owed to a number of factors, including in-depth editing by the novel’s agent, editor, and author to tighten up the plot, an extensive and strategic promotional campaign, the pandemic (which drove interest in the book’s genre and themes), and the quality of the writing. We find that the book’s success was accentuated by Osman’s celebrity status rather than being entirely reliant on it. This research adds to the growing scholarship on celebrity authorship by means of an in-depth case study and provides insight into the processes behind publishing a ‘celebrity’ book and launching a megabrand author
Isolasi Senyawa Flavonoida dari Buah Tumbuhan Kareumbi (Homalanthus Populneus (Geiseler) Pax)
No full textIsolation of flavonoid compounds from fruits of Kareumbi (Homalanthus populneus (Geiseler) Pax) has been done by maceration technique with methanol solvent. The concentrated extract of methanol dissolved with aquadest and partition extracted with ethyl acetate. The concentrated extract of ethyl acetate dissolved with methanol solvent, then partition with n-hexane. The concentrated extract of methanol separated with column chromatography with eluent chloroform : methanol (90:10; 80:20; 70:30; 60:40; 50:50) v/v as mobile phase. The fraction from chloroform : methanol (70:30) was crystallized to get a pure compound, yielding a yellow pasten with mass = 19,6 mg,and Rf = 0,73. And then, compounds were analyzed by UV-Visible, Infrared (FT-IR), and Proton Nuclear Magnetic Resonance Spectrometer (1H-NMR). Based on spectrofotometer analysis indicsted that the compound isolated is flavonoida an a flavonol.Isolasi senyawa flavonoida yang terdapat pada buah tumbuhan Kareumbi (Homalanthus populneus (Geiseler) Pax) telah dilakukan secara ekstraksi maserasi dengan pelarut metanol. Ekstrak pekat metanol dilarutkan dengan aquadest dan dipartisi dengan etil asetat. Ekstrak pekat etil asetat dilarutkan dengan metanol dan dipartisi dengan n-hekasana. Ekstrak pekat metanol dipisahkan dengan kromatografi kolom dengan eluen kloroform: metanol (90:10; 80:20; 70:30; 60:40; 50:50) v/v. Fraksi dari perbandingan kloroform: methanol (70:30) v/v dimurnikan dan dikristalisasi, menghasilkan pasta orange kekuningan sebanyak 19,6 mg dengan harga Rf = 0,73. Selanjutnya senyawa yang diperoleh dianalisis dengan spektrofotometer UV-Visible, Spektrofotometer Inframerah (FT-IR) dan Spektrometer Resonansi Magnetik Inti Proton (1H-NMR). Dari data analisis dan interpretasi spektroskopi, diduga bahwa senyawa hasil isolasi yang diperoleh adalah senyawa flavonoida yaitu golongan flavonol.53 HalamanSkripsi Sarjan
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