1000 resultados para Prerrogativa real
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Penaeidin from Chinese shrimp (Fenneropenaeus chinensis) has proved to be one of the most important antimicrobial peptides in the bodies of animals. The relative quantitative real-time PCR method is developed to study through time, the mRNA expression profile of penaeidin in the muscle and haemocyte tissue of Chinese shrimp infected with vibrio (Vibrio anguillarum) and WSSV (white spot syndrome virus). Research results showed that the same pathogens infection experiments produced similar gene expression profile in different tissues while different expression profiles appeared in the same tissues infected by different exterior pathogens. In vibrio infection experiments, a "U" Re expression profile resulted. Expression levels of penaeidin increased and surpassed the non-stimulated level, indicating that penaeidin from Chinese shrimp has noticeable antimicrobial activities. In WSSV infection experiments, the expression profile appeared as an inverse "U" with the expression of penaeidin gradually decreasing to below baseline level after 24 h. The expression of antimicrobial peptides gene in mRNA level in response to virus infection in shrimp showed that international mechanisms of virus to haemocytes and microbial to haemocytes are completely different. Decline of penaeidins expression levels may be due to haemocytes being destroyed by WSSV or that the virus can inhibit the expression of penaeidins by yet undiscovered modes. The expression profiles of penaeidin in response to exterior pathogen and the difference of expression profiles between vibrio and WSSV infection provided some clues to further understanding the complex innate immune mechanism in shrimp.
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Duplications and rearrangements of coding genes are major themes in the evolution of mitochondrial genomes, bearing important consequences in the function of mitochondria and the fitness of organisms. Yu et al. (BMC Genomics 2008, 9: 477) reported the complete mt genome sequence of the oyster Crassostrea hongkongensis (16,475 bp) and found that a DNA segment containing four tRNA genes (trnK(1), trnC, trnQ(1) and trnN), a duplicated (rrnS) and a split rRNA gene (rrnL5') was absent compared with that of two other Crassostrea species. It was suggested that the absence was a novel case of "tandem duplication-random loss" with evolutionary significance. We independently sequenced the complete mt genome of three C. hongkongensis individuals, all of which were 18,622 bp and contained the segment that was missing in Yu et al.'s sequence. Further, we designed primers, verified sequences and demonstrated that the sequence loss in Yu et al.'s study was an artifact caused by placing primers in a duplicated region. The duplication and split of ribosomal RNA genes are unique for Crassostrea oysters and not lost in C. hongkongensis. Our study highlights the need for caution when amplifying and sequencing through duplicated regions of the genome.
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This paper describes a machine vision system that classifies reflectance properties of surfaces such as metal, plastic, or paper, under unknown real-world illumination. We demonstrate performance of our algorithm for surfaces of arbitrary geometry. Reflectance estimation under arbitrary omnidirectional illumination proves highly underconstrained. Our reflectance estimation algorithm succeeds by learning relationships between surface reflectance and certain statistics computed from an observed image, which depend on statistical regularities in the spatial structure of real-world illumination. Although the algorithm assumes known geometry, its statistical nature makes it robust to inaccurate geometry estimates.
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The problem of automatic face recognition is to visually identify a person in an input image. This task is performed by matching the input face against the faces of known people in a database of faces. Most existing work in face recognition has limited the scope of the problem, however, by dealing primarily with frontal views, neutral expressions, and fixed lighting conditions. To help generalize existing face recognition systems, we look at the problem of recognizing faces under a range of viewpoints. In particular, we consider two cases of this problem: (i) many example views are available of each person, and (ii) only one view is available per person, perhaps a driver's license or passport photograph. Ideally, we would like to address these two cases using a simple view-based approach, where a person is represented in the database by using a number of views on the viewing sphere. While the view-based approach is consistent with case (i), for case (ii) we need to augment the single real view of each person with synthetic views from other viewpoints, views we call 'virtual views'. Virtual views are generated using prior knowledge of face rotation, knowledge that is 'learned' from images of prototype faces. This prior knowledge is used to effectively rotate in depth the single real view available of each person. In this thesis, I present the view-based face recognizer, techniques for synthesizing virtual views, and experimental results using real and virtual views in the recognizer.
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This report describes a knowledge-base system in which the information is stored in a network of small parallel processing elements ??de and link units ??ich are controlled by an external serial computer. This network is similar to the semantic network system of Quillian, but is much more tightly controlled. Such a network can perform certain critical deductions and searches very quickly; it avoids many of the problems of current systems, which must use complex heuristics to limit and guided their searches. It is argued (with examples) that the key operation in a knowledge-base system is the intersection of large explicit and semi-explicit sets. The parallel network system does this in a small, essentially constant number of cycles; a serial machine takes time proportional to the size of the sets, except in special cases.
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De-excited dynamics of p-chlorotoluene and p-dichlorobenzene have been investigated by the femtosecond pump-probe method in a supersonic molecular beam. The yields of the parent ion and daughter ion are examined as a function of the delay time between the pump and probe laser pulses. The lifetime constants of excited p-chlorotoluene and p-dichlorobenzene are determined. Possible de-excitation mechanisms are suggested that the initially excited S-1 state is predissociative via the repulsive triplet state. The substituent effects of additional chlorine atom and methyl group are discussed. Moreover, for the first time, we observe a novel quantum beat oscillation in p-dichlorobenzene. (c) 2005 Elsevier B.V. All rights reserved.
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A novel ligand modified heterogeneous catalyst has been developed for hydroformylation of propylene, which showed excellent activity, selectivity and stability and need not be separated from the product after reaction in a fixed-bed reactor. The coordination bonds between triphenyl phosphine (PPh3) and Rh/SiO2 were confirmed by means of thermogravimetric (TG), solid-state P-31 NMR, XPS and FT-IR. Two types of active species for hydroformylation were formed, which were proved by in situ FT-IR techniques. The problem of metal leaching was greatly reduced by directly fastening Rh particles on the support, and the active Rh species that was responsible for the outstanding performance of propylene hydroformylation was tightly bound by the very strong metal-metal bonds. No sign of deactivation was observed over a period of more than 1000 h on the condition that PPh3 was added at 300-350 h of time on stream. (c) 2005 Elsevier B.V. All rights reserved.
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Walker,J. and Garrett,S. and Wilson,M.S., 'Evolving Controllers for Real Robots: A Survey of the Literature', Adaptive Behavior, 2003, volume 11, number 3, pp 179--203, Sage
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Evans D A, Roberts O R, Vearey-Roberts A R, Langstaff D P, Twitchen D J and Schwitters M 2007 Direct observation of Schottky to ohmic transition in Al-diamond contacts using realtime photoelectron spectroscopy Appl. Phys. Lett. 91 132114 doi:10.1063/1.2790779
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Iantchenko, A., (2007) 'Scattering poles near the real axis for two strictly convex obstacles', Annales of the Institute Henri Poincar? 8 pp.513-568 RAE2008
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Real-time adaptive music is now well-established as a popular medium, largely through its use in video game soundtracks. Commercial packages, such as fmod, make freely available the underlying technical methods for use in educational contexts, making adaptive music technologies accessible to students. Writing adaptive music, however, presents a significant learning challenge, not least because it requires a different mode of thought, and tutor and learner may have few mutual points of connection in discovering and understanding the musical drivers, relationships and structures in these works. This article discusses the creation of ‘BitBox!’, a gestural music interface designed to deconstruct and explain the component elements of adaptive composition through interactive play. The interface was displayed at the Dare Protoplay games exposition in Dundee in August 2014. The initial proof-of- concept study proved successful, suggesting possible refinements in design and a broader range of applications.
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10 hojas : cuadros.
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http://www.archive.org/details/bypathstoforgott00haynrich
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Sonic boom propagation in a quiet) stratified) lossy atmosphere is the subject of this dissertation. Two questions are considered in detail: (1) Does waveform freezing occur? (2) Are sonic booms shocks in steady state? Both assumptions have been invoked in the past to predict sonic boom waveforms at the ground. A very general form of the Burgers equation is derived and used as the model for the problem. The derivation begins with the basic conservation equations. The effects of nonlinearity) attenuation and dispersion due to multiple relaxations) viscosity) and heat conduction) geometrical spreading) and stratification of the medium are included. When the absorption and dispersion terms are neglected) an analytical solution is available. The analytical solution is used to answer the first question. Geometrical spreading and stratification of the medium are found to slow down the nonlinear distortion of finite-amplitude waves. In certain cases the distortion reaches an absolute limit) a phenomenon called waveform freezing. Judging by the maturity of the distortion mechanism, sonic booms generated by aircraft at 18 km altitude are not frozen when they reach the ground. On the other hand, judging by the approach of the waveform to its asymptotic shape, N waves generated by aircraft at 18 km altitude are frozen when they reach the ground. To answer the second question we solve the full Burgers equation and for this purpose develop a new computer code, THOR. The code is based on an algorithm by Lee and Hamilton (J. Acoust. Soc. Am. 97, 906-917, 1995) and has the novel feature that all its calculations are done in the time domain, including absorption and dispersion. Results from the code compare very well with analytical solutions. In a NASA exercise to compare sonic boom computer programs, THOR gave results that agree well with those of other participants and ran faster. We show that sonic booms are not steady state waves because they travel through a varying medium, suffer spreading, and fail to approximate step shocks closely enough. Although developed to predict sonic boom propagation, THOR can solve other problems for which the extended Burgers equation is a good propagation model.