Página 16 dos resultados de 9995 itens digitais encontrados em 0.049 segundos

‣ Uso de jogo interativo na aprendizagem de estudantes de fonoaudiologia sobre o sistema miofuncional orofacial; Use of interactive game in speech language and hearing sciences students learning about the orofacial myofunctional system

Rondon, Silmara
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 19/10/2012 Português
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O objetivo deste estudo foi comparar dois métodos de aprendizagem sobre Anatomia e Fisiologia do Sistema Miofuncional Orofacial (SMFO) em estudantes do segundo ano do curso de Fonoaudiologia: método interativo (com uso de um jogo computacional) e método tradicional (com uso de textos resumidos associados a figuras pertinentes), no que se refere à aprendizagem e à retenção de conhecimento. Foram sujeitos do estudo 29 estudantes do segundo ano do curso de Fonoaudiologia os quais estavam cursando uma disciplina sobre Anatomia e Fisiologia do SMFO. A disciplina incluía aulas expositivas e um horário de estudo em que foram aplicados os dois métodos de aprendizagem propostos. Cada estudante foi alocado randomicamente em um dentre dois grupos: Grupo I (GI) 15 estudantes os quais foram submetidos ao método de aprendizagem por meio do jogo computacional; Grupo II (GII) 14 estudantes os quais foram submetidos ao método de aprendizagem tradicional. Os dois métodos foram desenvolvidos com a mesma duração (uma hora, uma vez por semana) e foram aplicados pelo mesmo tutor. O processo de randomização dos grupos foi mascarado. Os estudantes foram avaliados quanto aos conhecimentos prévios (préteste: antes da aplicação dos métodos de aprendizagem); quanto à retenção de conhecimento em curto prazo (pós-teste: imediatamente após a conclusão da aplicação dos métodos de aprendizagem) e quanto à retenção de conhecimento em longo prazo (pós-teste tardio: seis meses após a conclusão da aplicação dos métodos de aprendizagem). A avaliação foi realizada por aplicação de um questionário...

‣ How bioinformatics enables livestock applied sciences in the genomic era

Garcia, José Fernando; Do Carmo, Adriana Santana; Utsunomiya, Yuri Tani; De Rezende Neves, Haroldo Henrique; Carvalheiro, Roberto; Van Tassell, Curtis; Sonstegard, Tad Stewart; Da Silva, Marcos Vinicius Gualberto Barbosa
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 192-201
Português
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This review paper presents the three main approaches currently used in livestock genomic sciences where the bioinfomatics plays a critical role. They are named as Genomic Selection (GS), Genome Wide Association Study (GWAS) and Signatures of Selection (SS). The subsides for the construction of this article were generated in a current project (started in 2011), so called Zebu Genome Consortium (ZGC), which joins researchers from different institutions and countries, aiming to scientifically explore genomic information of Bos taurus indicus cattle breeds and deliver useful information to breeders and academic community, specially from the tropical regions of the world. © 2012 Springer-Verlag.

‣ The role of rigidity in DNA looping-unlooping by AraC

Harmer, Tara; Wu, Martin; Schleif, Robert
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 16/01/2001 Português
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We applied two experiments useful in the study of ligand-regulated DNA binding proteins to AraC, the dimeric regulator of the Escherichia coli l-arabinose operon. In the absence of arabinose, AraC prefers to loop DNA by binding to two half-sites that are separated by 210 base pairs, and in the presence of arabinose it prefers to bind to adjacently located half-sites. The basis for this ligand-regulated shift in binding appears to result from a shift in the rigidity of the system, where rigidity both in AraC protein in the absence of arabinose, and in the DNA are required to generate the free energy differences that produce the binding preferences. Eliminating the dimerization domains and connecting the two DNA binding domains of AraC by a flexible peptide linker should provide a protein whose behavior mimics that of AraC when there is no interaction between its dimerization and DNA binding domains. The resulting protein bound to adjacent half-sites on the DNA, like AraC protein in the presence of arabinose. When the two double-stranded DNA half-sites were connected by 24 bases of single-stranded, flexible DNA, wild-type AraC protein bound to the DNA in the presence and absence of arabinose with equal affinity, showing that AraC modulates its DNA binding affinity in response to arabinose by shifting the relative positions of its DNA binding domains. These results are consistent with the light switch mechanism for the action of AraC...

‣ Myoglobin: A scavenger of bioactive NO

Flögel, Ulrich; Merx, Marc W.; Gödecke, Axel; Decking, Ulrich K. M.; Schrader, Jürgen
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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The present study explored the role of myoglobin (Mb) in cardiac NO homeostasis and its functional relevance by employing isolated hearts of wild-type (WT) and myoglobin knockout mice. 1H NMR spectroscopy was used to measure directly the conversion of oxygenated Mb (MbO2) to metmyoglobin (metMb) by reaction with NO. NO was applied intracoronarily (5 nM to 25 μM), or its endogenous production was stimulated with bradykinin (Bk; 10 nM to 2 μM). We found that infusion of authentic NO solutions dose-dependently (≥ 2.5 μM NO) increased metMb formation in WT hearts that was rapidly reversible on cessation of NO infusion. Likewise, Bk-induced release of NO was associated with significant metMb formation in the WT (≥1 μM Bk). Hearts lacking Mb reacted more sensitively to infused NO in that vasodilatation and the cardiodepressant actions of NO were more pronounced. Similar results were obtained with Bk. The lower sensitivity of WT hearts to changes in NO concentration fits well with the hypothesis that in the presence of Mb, a continuous degradation of NO takes place by reaction of MbO2 + NO to metMb + NO3−, thereby effectively reducing cytosolic NO concentration. This breakdown protects myocytic cytochromes against transient rises in cytosolic NO. Regeneration of metMb by metMb reductase to Mb and subsequent association with O2 leads to reformation of MbO2 available for another NO degradation cycle. Our data indicate that this cycle is crucial in the breakdown of NO and substantially determines the dose–response curve of the NO effects on coronary blood flow and cardiac contractility.

‣ Evolution of treatment effects over time: Empirical insight from recursive cumulative metaanalyses

Ioannidis, John P. A.; Lau, Joseph
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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Evidence on how much medical interventions work may change over time. It is important to determine what fluctuations in the treatment effect reported by randomized trials and their metaanalyses may be expected and whether extreme fluctuations signal future major changes. We applied recursive cumulative metaanalysis of randomized controlled trials to evaluate the relative change in the pooled treatment effect (odds ratio) over time for 60 interventions in two medical fields (pregnancy/perinatal medicine, n = 45 interventions; myocardial infarction, n = 15 interventions). We evaluated the scatter of relative changes for different numbers of total patients in previous trials. Outlier cases were noted with changes greater than 2.5 standard deviations of the expected. With 500 accumulated patients, the pooled odds ratio may change by 0.6- to 1.7-fold in the immediate future. When 2000 patients have already been randomized, the respective figures are between 0.74- and 1.35-fold for pregnancy/perinatal medicine and between 0.83- and 1.21-fold for myocardial infarction studies. Extreme early fluctuations in the treatment effect were observed in three interventions (magnesium in myocardial infarction, calcium and antiplatelet agents for prevention of preeclampsia)...

‣ A stochastic model for the self-similar heterogeneity of regional organ blood flow

Kendal, Wayne S.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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The theory of exponential dispersion models was applied to construct a stochastic model for heterogeneities in regional organ blood flow as inferred from the deposition of labeled microspheres. The requirements that the dispersion model be additive (or reproductive), scale invariant, and represent a compound Poisson distribution, implied that the relative dispersion (RD = standard deviation/mean) of blood flow should exhibit self-similar scaling in macroscopic tissue samples of masses m and mref such that RD(m) = RD(mref). (m/mref)1−D, where D was a constant. Under these circumstances this empirical relationship was a consequence of a compound Poisson-gamma distribution that represented macroscopic blood flow. The model also predicted that blood flow, at the microcirculatory level, should also be heterogeneous but obey a gamma distribution—a prediction supported by observation.

‣ Cellular and molecular responses of the uterus to embryo implantation can be elicited by locally applied growth factors

Paria, Bibhash C.; Ma, Wen-ge; Tan, Jian; Raja, Shefali; Das, Sonjoy K.; Dey, Sudhansu K.; Hogan, Brigid L. M.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 30/01/2001 Português
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The implantation of a blastocyst into a receptive uterus is associated with a series of events, namely the attachment reaction followed by decidualization of the stroma. Previous studies established that the gene encoding heparin-binding EGF-like growth factor (HB-EGF) is expressed in the luminal epithelium solely at the site of blastocyst apposition preceding the attachment reaction. We report here the expression during implantation of 21 genes encoding other signaling proteins, including those belonging to the Bone morphogenetic protein (BMP), fibroblast growth factor (FGF), WNT, and Hedgehog (HH) pathways. We find that the attachment reaction is associated with a localized stromal induction of genes encoding BMP-2, FGF-2, and WNT-4. Despite efforts by many investigators, a simple in vitro model of implantation is not yet available to study either the hierarchy of the events triggered in the uterus by the embryo or the function of individual signaling proteins. We have therefore approached these questions by introducing beads loaded with purified factors into the receptive uterus. We show that beads soaked in HB-EGF or insulin-like growth factor-1 (IGF-1), but not other proteins, induce many of the same discrete local responses elicited by the blastocyst...

‣ Environmental stress and mutational load in diploid strains of the yeast Saccharomyces cerevisiae

Szafraniec, Krzysztof; Borts, Rhona H.; Korona, Ryszard
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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The negative effect of permanent contamination of populations because of spontaneous mutations does not appear to be very high if judged from the relatively good health of humans or many wild and domesticated species. This is partly explained by the fact that, in diploids, the new mutations are usually located in heterozygous loci and therefore are masked by wild-type alleles. The expression of mutations at the phenotypic level may also strongly depend on environmental factors if, for example, deleterious alleles are more easily compensated under favorable conditions. The present experiment uses diploid strains of yeast in which mutations arise at high rates because a mismatch-repair protein is missing. This mutagenesis resulted in a number of new alleles that were in heterozygous loci. They had no detectable effect on fitness when the environment was benign. A very different outcome was seen when thermal shock was applied, where fitness of the mutation-contaminated clones was lower and more diverse than that of the nonmutagenized clones. This shows that the genetic load conferred by spontaneous mutations can be underestimated or even overlooked in favorable conditions. Therefore, genetic variation can be higher and natural selection more intense when environmental conditions are getting poorer. These conclusions apply...

‣ Expression of Q227L-Gαs inhibits intimal vessel wall hyperplasia after balloon injury

Holness, Wilfred; Santore, Tara A.; Brown, George P.; Fallon, John T.; Taubman, Mark B.; Iyengar, Ravi
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 30/01/2001 Português
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Interaction between signaling pathways regulates many cellular functions, including proliferation. The Gαs/cAMP pathway is known to inhibit signal flow from receptor tyrosine kinases to mitogen-activated protein kinase (MAPK)-1,2 and, thus, inhibit proliferation. Elevation of cAMP or adenovirus-directed expression of mutant (Q227L)–Gαs (αs*) inhibits the proliferation of rat vascular smooth muscle cells (VSMCs) in culture. Platelet-derived growth factor (PDGF) stimulated MAPK activation and DNA synthesis was also blocked by expression of αs*. However, it is not known whether such mechanisms are operative in vivo. Proliferation of vascular smooth muscle cells in vivo was induced by balloon injury of carotid arteries in the rat. Recombinant adenovirus encoding β-galactosidase (β-gal) or αs* was applied to arterial segments injured by the balloon catheters. The αs*-treated vessels showed decreased phospho-MAPK staining in the intima as compared with β-gal-treated vessels. Application of αs*, but not β-gal containing adenovirus, inhibited formation of neointima by 50%. No change was observed in total vessel diameter or in the media or adventitia. These results suggest that the interaction between the Gαs and MAPK pathways can regulate proliferation in vivo and that targeted expression of activated Gαs may have therapeutic potential for the treatment of vascular pathophysiologies that arise from intimal hyperplasia.

‣ An arrayable flow-through microcentrifuge for high-throughput instrumentation

Marziali, Andre; Willis, Thomas D.; Davis, Ronald W.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 05/01/1999 Português
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A compact, flow-through centrifugation system has been developed specifically for high-throughput centrifugation of large numbers of samples. The instrument is based on multiple high-speed rotors that also serve as sample holders. The small size of the rotors allows them to be arrayed in a standard 96-well microtiter plate spacing, making this device ideal for highly parallel automated instrumentation. Though initially designed for cell separation in DNA sequencing protocols, the flow-through centrifuge can be used to replace conventional centrifugation in most processes involving small samples. Techniques for recovery of both the supernatant and the pellet have been developed, as well as techniques for sample mixing, and cleaning of the reusable rotors. This paper discusses the design and performance of the flow-through centrifuge applied to cell separation and resuspension and to DNA purification and concentration.

‣ Pseudechetoxin: A peptide blocker of cyclic nucleotide-gated ion channels

Brown, R. Lane; Haley, Tammie L.; West, Karen A.; Crabb, John W.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 19/01/1999 Português
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Ion channels activated by the binding of cyclic nucleotides first were discovered in retinal rods where they generate the cell’s response to light. In other systems, however, it has been difficult to unambiguously determine whether cyclic nucleotide-dependent processes are mediated by protein kinases, their classical effector enzymes, or cyclic nucleotide-gated (CNG) ion channels. Part of this difficulty has been caused by the lack of specific pharmacological tools. Here we report the purification from the venom of the Australian King Brown snake of a peptide toxin that inhibits current through CNG channels. This toxin, which we have named Pseudechetoxin (PsTx), was purified by cation exchange and RP-HPLC and has a molecular mass of about 24 kDa. When applied to the extracellular face of membrane patches containing the α-subunit of the rat olfactory CNG channel, PsTx blocked the cGMP-dependent current with a Ki of 5 nM. Block was independent of voltage and required only a single molecule of toxin. PsTx also blocked CNG channels containing the bovine rod α-subunit with high affinity (100 nM), but it was less effective on the heteromeric version of the rod channel (Ki ≈ 3 μM). We have obtained N-terminal and partial internal sequence data and the amino acid composition of PsTx. These data indicate that PsTx is a basic protein that exhibits some homology with helothermine...

‣ In vivo selection of functional ribosomes with variations in the rRNA-binding site of Escherichia coli ribosomal protein S8: Evolutionary implications

Moine, Hervé; Squires, Catherine L.; Ehresmann, Bernard; Ehresmann, Chantal
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 18/01/2000 Português
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The highly conserved nature of rRNA sequences throughout evolution allows these molecules to be used to build philogenic trees of different species. It is unknown whether the stability of specific interactions and structural features of rRNA reflects an optimal adaptation to a functional task or an evolutionary trap. In the work reported here, we have applied an in vivo selection strategy to demonstrate that unnatural sequences do work as a functional replacement of the highly conserved binding site of ribosomal protein S8. However, growth competition experiments performed between Escherichia coli isolates containing natural and unnatural S8-binding sites showed that the fate of each isolate depended on the growth condition. In exponentially growing cells, one unnatural variant was found to be equivalent to wild type in competition experiments performed in rich media. In culture conditions leading to slow growth, however, cells containing the wild-type sequence were the ultimate winner of the competition, emphasizing that the wild-type sequence is, in fact, the most fit solution for the S8-binding site.

‣ Landscape approaches for determining the ensemble of folding transition states: Success and failure hinge on the degree of frustration

Nymeyer, Hugh; Socci, Nicholas D.; Onuchic, José Nelson
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 18/01/2000 Português
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We present a method for determining structural properties of the ensemble of folding transition states from protein simulations. This method relies on thermodynamic quantities (free energies as a function of global reaction coordinates, such as the percentage of native contacts) and not on “kinetic” measurements (rates, transmission coefficients, complete trajectories); consequently, it requires fewer computational resources compared with other approaches, making it more suited to large and complex models. We explain the theoretical framework that underlies this method and use it to clarify the connection between the experimentally determined Φ value, a quantity determined by the ratio of rate and stability changes due to point mutations, and the average structure of the transition state ensemble. To determine the accuracy of this thermodynamic approach, we apply it to minimalist protein models and compare these results with the ones obtained by using the standard experimental procedure for determining Φ values. We show that the accuracy of both methods depends sensitively on the amount of frustration. In particular, the results are similar when applied to models with minimal amounts of frustration, characteristic of rapid-folding...

‣ Periodic Pulsed Controllability with Applications to NMR

Owrutsky, Philip
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
Português
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In this thesis we study a class of problems that require simultaneously controlling a large number of dynamical systems, with varying system dynamics, using the same control signal. We call such problems ensemble control problems, as the goal is to simultaneously steer the entire ensemble of systems. These problems are motivated by many physical systems and we will be particularly interested in the manipulation of nuclear spins in Nuclear Magnetic Resonance (NMR) experiments. System dispersion arise from imprecise magnets for controls, or from disruptive intermolecular interactions. In all cases, the aim is to attenuate the aspects fo the dynamics that correspond to noise or errors, while perserving the aspects that contain the quantities of interest. In liquid NMR experiments this could correspond to preserving Larmor frequency in the presence of inhomogeneities of the strength of the applied radio frequency (RF) field. In solid state NMR, reducing or eliminating orientation dependent magnetic fields is of key concern, so that a precise spectrum can be observed. We approach the problem from the standpoint of mathematical control theory in which the challenge is to simultaneously steer a continuum of systems between points of interest with the same control signal. At the heart of this problem is finding ways for the nonlinearity of the system to be used to our advantage...

‣ Synchronization of an array of spin torque nano oscillators in periodic applied external magnetic field

Subash, B.; Chandrasekar, V. K.; Lakshmanan, M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 03/04/2013 Português
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Considering an array of spin torque transfer nano oscillators (STNOs), we have investigated the synchronization property of the system under the action of a common periodically driven applied external magnetic field by numerically analyzing the underlying system of Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equations for the macro-spin variables. We find the novel result that the applied external magnetic field can act as a medium to induce synchronization of periodic oscillations, both in-phase and anti-phase, even without coupling through spin current, thereby leading to the exciting possibility of enhancement of microwave power in a straightforward way.; Comment: 6 pages, 8 figures, accepted for publication in Europhysics Letters

‣ Surrogate data method applied to nonlinear time series

Luo, Xiaodong; Nakamura, Tomomichi; Small, Michael
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 01/03/2006 Português
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The surrogate data method is widely applied as a data dependent technique to test observed time series against a barrage of hypotheses. However, often the hypotheses one is able to address are not those of greatest interest, particularly for system known to be nonlinear. In the review we focus on techniques which overcome this shortcoming. We summarize a number of recently developed surrogate data methods. While our review of surrogate methods is not exhaustive, we do focus on methods which may be applied to experimental, and potentially nonlinear, data. In each case, the hypothesis being tested is one of the interests to the experimental scientist.; Comment: Book chapter

‣ Applied Koopmanism

Budišić, Marko; Mohr, Ryan M.; Mezić, Igor
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
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A majority of methods from dynamical systems analysis, especially those in applied settings, rely on Poincar\'e's geometric picture that focuses on "dynamics of states". While this picture has fueled our field for a century, it has shown difficulties in handling high-dimensional, ill-described, and uncertain systems, which are more and more common in engineered systems design and analysis of "big data" measurements. This overview article presents an alternative framework for dynamical systems, based on the "dynamics of observables" picture. The central object is the Koopman operator: an infinite-dimensional, linear operator that is nonetheless capable of capturing the full nonlinear dynamics. The first goal of this paper is to make it clear how methods that appeared in different papers and contexts all relate to each other through spectral properties of the Koopman operator. The second goal is to present these methods in a concise manner in an effort to make the framework accessible to researchers who would like to apply them, but also, expand and improve them. Finally, we aim to provide a road map through the literature where each of the topics was described in detail. We describe three main concepts: Koopman mode analysis, Koopman eigenquotients...

‣ Applied Symbolic Vector Dynamics of Coupled Map Lattice

Wang, Kai; Pei, Wenjiang
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/07/2008 Português
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Symbolic dynamics, which partitions an infinite number of finite-length trajectories into a finite number of trajectory sets, describes the dynamics of a system in a simplified and coarse-grained way with a limited number of symbols. The study of symbolic dynamics in 1D chaotic map has been further developed and is named as the applied symbolic dynamics. In this paper, we will study the applied symbolic vector dynamics of CML. Based on the original contribution proposed in Refs.[6], we will study the ergodic property of CML. We will analyze the relation between admissibility condition and control parameters, and then give a coupling coefficient estimation method based on the ergodic property. Both theoretical and experimental results show that we provide a natural analytical technique for understanding turbulences in CML. Many of our findings could be expanded to a wider range of application.; Comment: 6pages, 4 figures,

‣ Membrane shape as a reporter for applied forces

Lee, Heun Jin; Peterson, Eric-L; Phillips, Rob; Klug, William S.; Wiggins, Paul A.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Article; PeerReviewed Formato: application/pdf; application/pdf
Publicado em 09/12/2008 Português
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Recent advances have enabled 3-dimensional reconstructions of biological structures in vivo, ranging in size and complexity from single proteins to multicellular structures. In particular, tomography and confocal microscopy have been exploited to capture detailed 3-dimensional conformations of membranes in cellular processes ranging from viral budding and organelle maintenance to phagocytosis. Despite the wealth of membrane structures available, there is as yet no generic, quantitative method for their interpretation. We propose that by modeling these observed biomembrane shapes as fluid lipid bilayers in mechanical equilibrium, the externally applied forces as well as the pressure, tension, and spontaneous curvature can be computed directly from the shape alone. To illustrate the potential power of this technique, we apply an axial force with optical tweezers to vesicles and explicitly demonstrate that the applied force is equal to the force computed from the membrane conformation.

‣ Applied Mechanics Dynamics

Housner, George W.; Hudson, Donald E.
Fonte: California Institute of Technology Publicador: California Institute of Technology
Tipo: Book; NonPeerReviewed Formato: application/pdf
Publicado em //1980 Português
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The present edition incorporates a number of revisions and additions which should improve its usefulness as a textbook without changing the basic organization or the general philosophy of presentation of the subject matter. The experience of the past few years at the California Institute of Technology and other schools indicates that the book has been useful to engineering students who wish to prepare for more advanced studies and applications of dynamics, and hence a new edition was felt to be justified. Among the additions and modifications the following may be mentioned to indicate the scope of the revision. The section on dimensional analysis has been rewritten and a brief treatment of the theory of models has been added. The section on impact problems has been revised, and a more extensive treatment of variable mass systems has been included. A more general discussion of the moment of momentum equations for systems of particles has been added, and the general momentum and energy equations for rigid bodies have been more completely developed. The discussion of rotation about a fixed point and gyroscopic motion has been expanded and somewhat more complex systems have been considered, including problems on the stability of rolling motion. The problem of longitudinal waves in an elastic bar is discussed...