52,818 research outputs found
Brachylepadomorpha WITHERS 1923
No full text††ORDER BRACHYLEPADOMORPHA WITHERS, 1923 Diagnosis: Symmetrical, pedunculated and sessile forms, in which the large carina and rostrum are surrounded by alternating rows of imbricating plates. Comment: The order is paraphyletic and includes s p e c i e s t h a t f o r m a s t e m g r o u p t o b o t h t h e Verrucomorpha and the Balanomorpha.Published as part of Chan, Benny K. K., Dreyer, Niklas, Gale, Andy S., Glenner, Henrik, Ewers-Saucedo, Christine, Pérez-Losada, Marcos, Kolbasov, Gregory A., Crandall, Keith A. & Høeg, Jens T., 2021, The evolutionary diversity of barnacles, with an updated classification of fossil and living forms, pp. 789-846 in Zoological Journal of the Linnean Society 193 on page 832, DOI: 10.1093/zoolinnean/zlaa160, http://zenodo.org/record/563727
Portrait of Professor H. Rodney Withers [picture] /
No full textTitle supplied by photographer.; Photograph signed and dated by artist on verso.; Also available in an electronic version via the Internet at: http://nla.gov.au/nla.pic-vn3579894; Purchased from the photographer, 2005. Dr. Withers is considered by many colleagues to be the pre-eminent clinically-oriented radiation biologist in the world. He has made numerous scientific contributions over the years, but is most widely known for his seminal work on post-radiation repair and the effects of ionizing radiation on normal tissues. Many of the assays and the techniques he has developed are now being used in laboratories throughout the world. There is scarcely any major review of radiation biology which does not cite Dr. Withers' contributions prominently, and he stands out as the radiation biologist who has applied studies on basic radiation effects to the clinical practice of radiation therapy. Dr. Withers has received many prestigious awards, including the Henry S. Kaplan Distinguished Scientist Award from the International Association for Radiation Research, the Gold Medal from the American Society of Therapeutic Radiology and Oncology, the Gaggin Fellowship for Cancer Research (Australia), the Finzi Bequent Prize (British Institute of Radiology), the University of Texas Commemorative Medal of Achievement, the Failla Award (Radiation Research Society), the Polish Academy of Science Medicine Prize, a National Cancer Institute Merit Award, and in 1995 the Gray Medal. He is also a Fellow of the American Cancer Society. Reference: http://www.radbiol.ucla.edu/Faculty/Rod.htm
Experimental investigation of plasma impedance in Linac4 source
No full textCERN ’s new particle accelerator Linac4 is part of the upgrade of the LHC accelerator chain. Linac4 is required to deliver 160 MeV H− beam to improve the beam brightness and luminosity in the Large Hadron Collider (LHC). The Linac4 H− source must deliver 40-50 mA, 45 keV H− beam in the RFQ acceptance. Since the RF power coupled to the H− source plasma is one of the important parameters that determines the quality of the H− beam, the experimental investigation of the dependence of the load impedance on the operational parameters is mandatory. In this study, we have measured the impedance of the H− source plasma varying the RF power coupled to the plasma and the condition of the hydrogen gas. Also, optical emission spectroscopy (OES) measurements have been carried out simultaneously with the impedance measurement in order to determine the plasma parameters. The determination of the plasma parameters allows us to compare the experimental results with the analytic model of the plasma parameters, which is useful to discuss the results from a physical point of view
Eigenstrain modelling of residual stress generated by arrays of Laser Shock Peeing shots and determination of the complete stress field using limited strain measurements
No full textThis paper presents a hybrid explicit finite element (FE) /eigenstrain model for predicting the residual stress generated by arrays of adjacent/overlapping laser shock peening (LSP) shots where the use of a completely explicit FE analysis may be impractical. It shows that for a given material, the underlying eigenstrain distribution (in contrast to the resulting stress field) representing a laser shock peen is primarily dependent on the parameters of the laser pulse and the number of overlays rather than the precise component geometry. Consequently the residual stress introduced by complex laser peening treatments can be built up by using static FE models and superposition of individual eigenstrain distributions without recourse to further computationally demanding explicit FE analyses. It is found that beneath a small patch of LSP array the magnitude of the compressive residual stress is higher than for a wider array of LSP shots and that with increasing numbers of layers the compressive stress increases as does the depth of the compressive zone. The model predictions for the eigenstrain distributions are compared well with experimental measurements of plastic strain (full-width-at-half-maximum) obtained by neutron diffraction. The eigenstrain method is also extended to construct the full residual stress field using measured residual elastic strains at a finite number of measurement locations in a component.<br/
Influence of the cusp field on the plasma parameters of the Linac4 H− ion source
No full textWhen the H ion source of CERN’s Linac4 is operated in volume mode, a maximum of the extracted current is obtained at varying RF power. The power required for this maximum and its absolute value is strongly influenced by the cusp magnets installed at the source for electron confinement: without magnets, 15−20 mA are typically obtained at 20 kW whereas with magnets a factor of two more power is needed and 25−30 mA are achieved. In order to access the reasons behind the peaked performance with varying RF power and for determining the influence of the cusp field on the discharge, optical emission spectroscopy (OES) measurements of the atomic Balmer series and of the molecular Fulcher transition have been carried out. In all investigated cases, the gas temperature of the discharge has been virtually equal to the ambient temperature as the short discharge pulse length of 500 s is not long enough for considerable heavy particle heating. When no cusp magnets are installed, the plasma parameters evaluated with the collisional radiative models Yacora H and Yacora H show a minimum in the electron temperature of 3.25 eV and a maximum in the electron density of and also in the vibrational excitation of the hydrogen molecule at 20 kW. Assessing the relevant production and destruction processes demonstrates that the H yield is maximal at this point thereby explaining the optimum ion source performance. When the cusp magnets are applied, the same general trends are observed but the required RF power is a factor of two higher. The OES results indicate an optimum performance around 30 kW whereas the highest H current is actually achieved around 40 kW. Furthermore, a higher H yield is indicated without cusp magnets but a better ion source performance is observed with magnets. These differences can most likely be attributed to changing gradients in the plasma parameters which are not accessible by OES. Nevertheless, the obtained plasma parameters can be used as benchmark for RF coupling codes simulating the Linac4 ion source
A molecular dynamics study of N-A-S-H gel with various Si/Al ratios
No full textThe understanding of sodium aluminosilicate hydrate (N-A-S-H) gel is still limited due to its complex and amorphous structure. Recently, molecular dynamics simulation has provided a unique opportunity to better understand the structure of N-A-S-H gel from nanoscale. In this work, the N-A-S-H gel structure was obtained by simulating the polymerization of Si and Al monomers by molecular dynamics. The simulated polymerization process is in good agreement with the experimental results especially in terms of the reaction rate of Si and Al species. The atomic structural features of the N-A-S-H gel were analyzed in terms of bond length and bond angle information, simulated X-ray diffraction (XRD) and Qn distribution. A significant finding is the existence of pentacoordinate Al in all simulated N-A-S-H structures, indicating that pentacoordinate Al in geopolymer does not only come from raw material. Besides, the results show that a smaller Si/Al ratio led to a more crosslinked and compacted structure of N-A-S-H gel
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
Effects of the extraction voltage applied by the puller-electrode on the H extraction in the Linac4 negative ion source
No full textIn order to understand the H extraction mechanism and investigate the effect of the extraction voltage applied by the puller-electrode on the H extraction in the Linac4 negative ion source, we are developing a 2D3V-PIC (two dimensions in the real space and three dimensions in the velocity space, Particle in Cell) model with volume produced H ions. It is shown that how to take the magnetic filter field direction is important for the 2D modeling to take into account the important 3D effect of electron drift. It is also shown that the meniscus formation is not symmetric due to the electron drift in the extraction region and the divergence of the H beam is asymmetric. In order to make more quantitative comparison of the extracted H and electron currents with the experiments and 3D modeling, further improvements, especially the electron loss along the magnetic filter field line will be needed
Book Review: Review of Daryl Gregory, The Album of Dr. Moreau ; J. S. Barnes, The City of Dr Moreau ; The Daughter of Doctor Moreau
No full textH. G. Wells’s The Island of Doctor Moreau (1896) has in recent years been enjoying a cultural moment. Since 2021, three different literary continuations of Wells’s work written by three different authors have appeared: The Album of Dr. Moreau (2021) by Daryl Gregory, The City of Dr Moreau (2021) by J. S. Barnes, and The Daughter of Doctor Moreau (2022) by Silvia Moreno-Garcia. These continuations take the form of prequels, sequels, and alternative histories to the events depicted in Wells’s original novel. Of course, this surge of interest is not totally surprising given that, since his arrival on the British literary scene in the 1890s, Wells has never disappeared from the larger cultural landscape. In particular, his science fictional masterpieces that he wrote early in his career (and that include The Island of Doctor Moreau) have been blessed with an impressive longevity. These works have never gone out of print, and countless writers, editors, filmmakers, and musicians have returned to them as a perennial source of stimulation and authority.This book review is published as Withers, Jeremy., Daryl Gregory, The Album of Dr. Moreau (New York: Tordotcom, 2021); J. S. Barnes, The City
of Dr Moreau (London: Titan, 2021); Silvia Moreno-Garcia, The Daughter of Doctor Moreau (New York: Del Rey, 2022). The Wellsian. 46 (2023); 84-86. http://hgwellssociety.com/wellsian/. Posted with permission
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
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