104,147 research outputs found
Spatial pattern of nerve differentiation in Hydra is due to a pattern of nerve commitment
No full textThe pattern of nerve differentiation along the body column of Hydra was investigated. Nerve precursors in late S phase were labeled with [3H]thymidine and their distribution compared with that of newly differentiated nerves. The two distributions were found to be the same. Based on independent evidence that nerve commitment occurs in mid-to late S phase (G. Venugopal and C. David, 1981, Develop. Biol.83, 361–365) it was concluded that the pattern of nerve differentiation along the body column of Hydra is due to differences in nerve commitment in different body regions. Furthermore, the level of nerve commitment in head and foot tissue is sufficiently high to deplete stem cells in these regions as is observed
Nerve commitment in Hydra. II. Localization of commitment in S phase
No full textThe kinetics of nerve differentiation were investigated during head regeneration in Hydra. In particular the cell cycle parameters of stem cells undergoing nerve commitment were determined. Head regeneration induces extensive nerve commitment localized at the regenerating tip (G. Venugopal and C. David, 1981, Develop. Biol.83, 353–360). The appearance of committed nerve precursors is followed 12 hr later by the appearance of newly differentiated nerves. Under these conditions the time from the end of S phase to nerve differentiation is about 9 hr and the time from the beginning of S phase to nerve differentiation is about 18 hr. Thus nerve commitment occurs in mid- to late S phase of the stem cell precursor
Lewis Base Induced Reductions in Organolanthanide Chemistry
No full textBojer D, Venugopal A, Neumann B, Stammler H-G, Mitzel NW. Lewis Base Induced Reductions in Organolanthanide Chemistry. ANGEWANDTE CHEMIE-INTERNATIONAL EDITION. 2010;49(14):2611-2614
Drag and inertia coefficients for horizontally submerged rectangular cylinders in waves and currents
No full textThe results of an experimental investigation carried out to measure combined wave and current loads on horizontally submerged square and rectangular cylinders are reported in this paper. The wave and current induced forces on a section of the cylinders with breadth-depth (aspect) ratios equal to 1, 0.5, and 0.75 are measured in a wave tank. The maximum value of Keulegan-Carpenter (KC) number obtained in waves alone is about 5 and Reynolds (Re) number ranged from 6.3976103 to 1.186105. The drag (CD) and inertia (CM) coefficients for each cylinder are evaluated using measured sectional wave forces and particle kinematics calculated from linear wave theory. The values of CD and CM obtained for waves alone have already been reported (Venugopal, V., Varyani, K. S., and Barltrop, N. D. P. Wave force coefficients for horizontally submerged rectangular cylinders. Ocean Engineering, 2006, 33, 11-12, 1669-1704) and the coefficients derived in combined waves and currents are presented here. The results indicate that both drag and inertia coefficients are strongly affected by the presenceof the current and show different trends for different cylinders. The values of the vertical component inertia coefficients (CMY) in waves and currents are generally smaller than the inertia coefficients obtained in waves alone, irrespective of the current's magnitude and direction. The results also illustrate the effect of a cylinder's aspect ratio on force coefficients. This study will be useful in the design of offshore structures whose columns and caissons are rectangular sections
Aggregate breakdown of nanoparticulate titania
No full textSix nanosized titanium dioxide powders synthesized from a sulfate process were investigated. The targeted end-use of this powder was for a de-NOx catalyst honeycomb monolith. Alteration of synthesis parameters had resulted principally in differences in soluble ion level and specific surface area of the powders. The goal of this investigation was to understand the role of synthesis parameters in the aggregation behavior of these powders. Investigation via scanning electron microscopy of the powders revealed three different aggregation iterations at specific length scales.
Secondary and higher order aggregate strength was investigated via oscillatory stress rheometry as a means of simulating shear conditions encountered during extrusion. G' and G'' were measured as a function of the applied oscillatory stress. Oscillatory rheometry indicated a strong variation as a function of the sulfate level of the particles in the viscoelastic yield strengths. Powder yield stresses ranged from 3.0 Pa to 24.0 Pa of oscillatory stress. Compaction curves to 750 MPa found strong similarities in extrapolated yield point of stage I and II compaction for each of the powders (at approximately 500 MPa) suggesting that the variation in sulfate was greatest above the primary aggregate level. Scanning electron microscopy of samples at different states of shear in oscillatory rheometry confirmed the variation in the linear elastic region and the viscous flow regime.
A technique of this investigation was to approach aggregation via a novel perspective: aggregates are distinguished as being loose open structures that are highly disordered and stochastic in nature. The methodology used was to investigate the shear stresses required to rupture the various aggregation stages encountered and investigate the attempt to realign the now free-flowing constituents comprising the aggregate into a denser configuration. Mercury porosimetry was utilized to measure the pore size of the compact resulting from compaction via dry pressing and tape casting secondary scale aggregates. Mercury porosimetry of tapes cast at 0.85 and 9.09 cm/sec exhibited pore sizes ranging from 200-500 nm suggesting packing of intact micron-sized primary aggregates. Porosimetry further showed that this peak was absent in pressed pellets corroborating arguments of ruptured primary aggregates during compaction to 750 MPa.Ph.D.Includes bibliographical references (p. 166-170)
Use of vacuum-formed retainer for extrusion of a grossly decayed tooth using auxiliaries
No full textIntroduction: Vacuum-formed retainers are one of the most used retainers because of their esthetic advantage, ease of fabrication as well as the low fabrication cost. While aligners are usually associated with improved esthetics the extended period required to obtain these is one of the reasons the present modification was introduced to achieve the desired tooth movement with patient cooperation. Patient Diagnosis: The patient aged 35 years old came with a missing clinical crown and pain in relation to tooth 11 and was advised to receive re-endodontic treatment. The main finding on intra-oral examination was that the patient’s incisor root was submerged below the gingiva. Clinical innovation: The present innovation describes the use of a vacuum-formed retainer for carrying out movement of a grossly decayed tooth with no clinical crown. While clear retainers are meant for retention their durability can be used as an added advantage for carrying out specific movements with the aid of auxiliary attachments. The main benefits of this innovation were in terms of the time to initiate treatment and cost reduction. Discussion: This appliance is extremely easy to fabricate and does not require extensive scans and treatment planning especially in case of a patient that does not desire a lengthy treatment. Aligners are cost-effective but only when produced in-house which is why clear retainers with auxiliary attachments can be used as a low-cost option when only minor tooth movements are required
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
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
RS_GV at SemEval-2021 Task 1: Sense Relative Lexical Complexity Prediction
No full textStodden R, Venugopal G. RS_GV at SemEval-2021 Task 1: Sense Relative Lexical Complexity Prediction. In: Proceedings of the 15th International Workshop on Semantic Evaluation (SemEval-2021). Stroudsburg, PA, USA: Association for Computational Linguistics; 2021: 640-649.We present the technical report of the system called RS_GV at SemEval-2021 Task 1 on lexical complexity prediction of English words. RS_GV is a neural network using hand-crafted linguistic features in combination with character and word embeddings to predict target words’ complexity. For the generation of the hand-crafted features, we set the target words in relation to their senses. RS_GV predicts the complexity well of biomedical terms but it has problems with the complexity prediction of very complex and very simple target words
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