308,052 research outputs found
Keith Gendreau, Mark Bautz, George Ricker
No full textWe report measurements of effects of 2.1 MeV and 40 MeV protons on Charge Coupled Device X-ray detectors of a type soon to be launched on several astronomical research satellites. We discuss ground performance characterization techniques and compare our measurements to simple models of the detector damage mechanism. We predict detector peformance degradation rates in low-earth orbit. We plan to compare these predictions to early flight data obtained from the Solid State Imaging Spectrometer (SIS) focal plane instrument mounted on the Japan/US X-ray astronomy satellite Asuka launched on February 20, 1993. Introduction At MIT, we are developing photon counting imaging x-ray spectrometers using Charge Coupled Device (CCD) detectors for several astronomical research satellites. The first of these, the Japan/US mission Asuka, has been developed jointly by the Japanese Institute for Space and Aeronautical Science (ISAS) and the National Aeronautics and Space Administration (NASA) (Ricker e..
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
A dinâmica do modelo populacional de Ricker
No full textO modelo de Ricker é um dos vários modelos utilizados em ecologia para descrever a dinâmica
populacional que depende da densidade ao longo do tempo, observada em intervalos de tempo
discreto. Este modelo é adequado para estudar espécies onde as estimativas anuais (ou
geracionais) de abundância são caracterizadas adequadamente como dinâmica populacional e para
transições entre estágios da história de vida, tais como produção de descendentes ou sobrevivência
de um estágio para o próximo. A última aplicação é comum na ciência da pesca, onde o modelo
de Ricker é frequentemente usado para relacionar a produção de recrutas (peixes jovens que
sobrevivem para se juntar à população) a fatores na densidade observada, tais como abundância,
biomassa total ou potencial total de desova de peixes adultos, como parte de um modelo
populacional abrangente.
O objetivo deste trabalho é aplicar alguns resultados da teoria de estabilidade de sistemas
dinâmicos discretos ao Modelo de Ricker. Em particular, estudamos a dinâmica populacional em
ambos os casos, no modelo autónomo e no modelo não autónomo.The Ricker model is one of several models used in ecology to describe population dynamics that
depend on density over time, observed at discrete intervals. This model is suitable for studying
species where annual (or generational) estimates of abundance are adequately characterized as
population dynamics, and for transitions between life history stages, such as offspring production
or survival from one stage to the next. The latter application is common in fisheries science, where
the Ricker model is frequently used to relate the production of recruits (young fish that survive to
join the population) to factors in observed density, such as abundance, total biomass, or total
potential spawning of adult fish, as part of a comprehensive population model.
The objective of this work is to apply some results from the theory of stability of discrete dynamic
systems in the Ricker model. In particular, we study population dynamics in both autonomous and
non-autonomous cases
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
Allocapnia indianae Ricker 1952
No full textAllocapnia indianae Ricker (Figs. 49-54) Allocapnia indianae Ricker 1952:162. Holotype ♀ (Illinois Natural History Survey), creek northwest of Medora, [Jackson Co.], Indiana Allocapnia indianae: Ross & Ricker, 1971:47. Material examined. Kentucky: Carter Co., Grassy Creek, Hwy AA9, 3 March 2001, B.C. Kondratieff, R.F. Kirchner, R. E. Zuellig, 152♂, 19♀ (CSUC). Lewis Co., Kinniconick Creek, SE Vanceburg, 3 March 2001, B.C. Kondratieff, R.F. Kirchner, R. E. Zuellig, 11♂ (CSUC). Lincoln Co., Green River, Hwy 698, Jumbo, 3 March 2001, B.C. Kondratieff, R.F. Kirchner, R.E. Zuellig, 3♂ (CSUC). Male epiproct. Apical segment of upper limb ca. 265- 277 μm long, armed on apical ca. 152-172 μm with dense patch of wave-like spikes (Figs. 49-52); apical segment ca. 100-106 μm wide at base, tapered to a narrow rounded tip. Basal segment of upper limb ca. 257 μm long and ca. 65-67 μm wide at midlength; basal segment with a broad, shallow, median groove. Greatest width of lower limb ca. 176-187 μm; lower limb bears a sparse, marginal row of long setae in apical third (Fig. 49). Male tergal process. Prominent raised structures on abdominal terga 7 and 8 (Figs. 53-54). Trilobed process of tergum 8 ca. 140-146 μm wide and bearing a broad, shallow median notch, interrupted by median projection. Lobes of process covered with scale-like structures; anterior face of process bears a deep transverse groove (Fig. 53). In lateral aspect, lobes extend vertically as thin discs set on narrow bases. Process of tergum 7 ca. 100 μm wide; similar in structure to 8 th tergal process.Published as part of Stark, Bill P. & Kondratieff, Boris C., 2012, Epiproct And Dorsal Process Structure In The Allocapnia Forbesi Frison, A. Pygmaea (Burmeister), And A. Rickeri Frison Species Groups (Plecoptera: Capniidae), And Inclusion Of A. Minima (Newport) In A New Species Group, pp. 45-77 in Illiesia 8 (5) on page 60, DOI: 10.5281/zenodo.476072
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
Calling: Earth #009 - Faye Ricker, Energy Geographer
No full textFaye Ricker, a doctoral candidate in the USF School of Geosciences, discusses her research into socio-cultural and socio-economic implications from geothermal energy development in Kenya.
More about Faye can be found here:
https://scholar.google.com/citations?user=F-E9DrUAAAAJ&hl=e
[Report to Chief J. E. Curry, by an unknown author #2]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
- …
