bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some Developments in Boundary Layer Research in the Past Thirty Years
Authors: Schlichting H. 
Published: July 2016

SummaryBoundary layer theory is the cornerstone of our knowledge of the flow of air and other fluids of small viscosity under circumstances of interest in many engineering applications, especially also in aeronautics. Many complex problems in aerodynamics, as for instance the problem of skin friction, which was theoretically attacked very early by F. W. Lanchester, have been clarified by studying the flow within the boundary layer and its effects on the general flow around the body.Research work on boundary layers, as started by Prandtl in 1904. was for the first twenty years—up to Prandtl's Wilbur Wright Memorial Lecture to the Royal Aeronautical Society in 1927—almost entirely restricted to Prandtl's Institute at Göttingen. But since about 1930 boundary layer theory has been generally accepted, and in the past thirty years there has been an almost exponential rise of the number of contributors to its further development.The author tries to trace certain lines, along which this important branch of modern fluid dynamics has developed in the past thirty years. In this connection the following topics are treated to some extent:I.Transition from laminar to turbulent flow.II.Boundary layer control for high lift and low drag of aerofoils.III.Aerodynamic heating at high speed (high Mach numbers).IV.Boundary layer efff cts on swept wings and on rotating bodies.I. The theoretical investigations of the problem of transition start from Reynolds' and Lord Rayleigh's hypothesis of the instability of laminar flow. After many unsuccessful attempts Tollmien, 1930, finally succeeded in calculating the critical Reynolds number for the boundary layer on a flat plate. More than ten years later Tollmien's stability theory was completely confirmed by very careful experiments of Dryden and his co-workers.II. After many wind tunnel experiments the investigations of boundary layer control for high lift of aerofoils led to the construction of two aeroplanes with boundary layer suction at the aerodynamische versuchsanstalt gottingen, in 1938, which were quite successful. later on, also, a considerable reduction of the skin friction of aerofoils was obtained with the advent of the laminar flow aerofoil.III. In flow at high Mach numbers the velocity boundary layer is accompanied by a thermal boundary layer which is caused by frictional heating. The large increase in the temperature of a solid surface in a high speed stream which can be calculated from boundary layer theory only, poses a serious problem to aeronautical engineers (“thermal barrier”).IV. The aerodynamic characteristics of swept wings and Delta wings are largely governed by the behaviour of their boundary layer. Some of the draw-backs of such wing plan forms can be remedied by boundary layer control, as for instance by a “boundary layer fence.” For turbo-machines the influence of the centrifugal forces on the boundary layer plays an important role for their aerodynamic coefficients.
Some Practical Aspects of Compressor Blade Vibration
Authors: Armstrong E. K. , Stevenson R. E. 
Published: July 2016

The object of this paper is to set down an overall picture of the practical aspects of compressor blade vibration. In doing so it is inevitable that a certain content is effectively a repeat of other people's contributions to the subject. The authors make no apology for this and offer the paper as a "state of the art" as practised at Bristol Siddeley Engines Ltd. In bringing together the many relevant issues of this problem, it is hoped that a useful presentation is obtained.There is little hesitation in indicating the most obvious and important practical aspect of blade vibration as that of the inherent danger of blade failure and it is known that the axial flow compressor is susceptible to complete failure caused by the fatigue of one blade.The multi-stage axial flow compressor is a highly complex aerodynamic machine with, its early and late stages required to operate over wide ranges of incidence and Mach number conditions. To some extent, of course, use of variable geometry can reduce this to less taxing proportions. The aerodynamic environment of front stages has broad boundaries somewhat wider than those relating to rear stages, while middle blade rows generally operate under sensibly constant conditions. This diminishing “severity” of operation, front, rear to middle stage blading is not unrelated to the incidence of blade vibration problems which shows a similar pattern.
Free Vibration and Hysteretic Damping
Authors: Lancaster P. 
Published: July 2016

I would like to add yet another note to those already published on the notions of viscous and hysteretic damping in a simple oscillator. In particular, I would like to hammer a nail into the coffin of the so-called “complex stiffness.“One of the features which hysteretic damping may be defined to possess is the property that the energy loss per cycle (in sinusoidal motion) is independent of the frequency of oscillation, ω. This property is derived from some experimental evidence. It is shown in Reference 1 that this behaviour is reproduced by the particular integral of the equation
A Simplified Method for Estimating the Properties of Thin Aerofoils Influenced by Jet
Authors: Pivko Svetopolk 
Published: July 2016

To predict the aerodynamical properties of a thin aerofoil, provided with a high velocity jet sheet in its trailing edge region, a simple procedure is proposed as follows. Two general separate cases concerned with the effect of a jet on an aerofoil are considered. In the first case, the jet is blown tangentially over the upper surface of the aerofoil, while in the second case, the jet is ejected at a deflection angle from the trailing edge. In this analysis a procedure which is similar to the classical Glauert treatment of thin aerofoils is applied.Consider first the special case of a thin aerofoil placed at zero incidence in a two-dimensional inviscid flow of velocity V0, with a jet emerging with an exit velocity V1 at distance x1 from the leading edge and blown tangentially over the upper surface of the aerofoil (Fig. 1). It is assumed that an effectively attached flow may be obtained.
Supersonic Flutter of a Cylindrical Panel in an Axi–Symmetric Mode
Authors: Johns D. J. 
Published: July 2016

In ref. 1 an extensive review was made of the panel flutter problem and analyses dealing with flutter of cylindrical shells of finite length were discussed in considerable detail. It was stated that one of the central points of controversy is in the choice of the appropriately simplified governing equations for the thin–walled elastic shell. Related to this is the choice of flutter mode and the question as to how the critical flutter speed depends upon the number of circumferential and axial waves in that mode.Stepanov and Strack and Holt found that the critical Mach number decreases with increasing number of circumferential waves, and Fung has concluded that the axially symmetric mode is of the greatest interest.The purpose of this note is to present a relatively simple analysis in which only axi–symmetric deformations of the shell are considered. The shell is assumed to be unreinforced longitudinally.
Mathematics and Aeronautics
Authors: Lighthill M. J. 
Published: July 2016

The 48th Wilbur Wright Memorial Lecture, “Mathematics and Aeronautics” was given by Mr. M. J. Lighthill, F.R.S., before a large and distinguished audience at the Institution of Mechanical Engineers, 1 Birdcage Walk, on 19th May 1960. Dr. E. S. Moult, C.B.E., B.Sc, F.R.Ae.S., M.I.Mech.E., President of the Society, presided.As has become the custom, before the lecture was delivered the President presented the awards made by the Council for 1960 for outstanding contributions to aeronautics. In the unavoidable absence of the Secretary he was assisted by Miss E. C. Pike, M.A., A.F.R.Ae.S., Secretary of the Medals and Awards Committee and Editor of The Aeronautical Quarterly. The list of the awards presented on this occasion was published in the June 1960 Journal—(p. XXXII).The President, introducing the lecturer, reminded the audience that the Wilbur Wright Lecture commemorated the first manned, powered controlled flight by Wilbur Wright at Kitty Hawk, North Carolina on 17th December 1903. The first Wilbur Wright Memorial Lecture was held in 1913 and they had been held each year ever since, through two World Wars; in itself a wonderful record. The custom had been, and would continue to be, to have alternately a lecturer from the United Kingdom and a lecturer from the United States; last year the lecture had been by Mr. McCarthy of Chance Vought and next year again it would be by an American.The Wilbur Wright Lectures had been a most distinguished series by distinguished lecturers, and he was sure that the lecture that night would be in keeping. His pleasant duty was to introduce Professor Lighthill—or as they had to call him Mr. Lighthill now that he was Director of the Royal Aircraft Establishment, which was an even greater distinction. Mr. Lighthill was the youngest Director that the R.A.E. had ever had—that alone was a tribute to Mr. Lighthill's ability and his high standing in the profession. Before joining the Royal Aircraft Establishment Mr. Lighthill was Professor of Applied Mathematics at Manchester University, and for a time, after leaving Cambridge, had worked at the National Physical Laboratory where he applied the mathematics of Cambridge to the problems of aerodynamics. His lecture was on “Mathematics and Aeronautics” he would ask Mr. Lighthill to deliver the 48th Wilbur Wright Memorial Lecture.
Some British Research on the Basic Aerodynamics of Powered Lift Systems
Authors: Williams John 
Published: July 2016

Summary:The paper mainly discusses recent R.A.E. and N.P.L. research on the aerodynamics of Direct jet lift (turbo-jet and turbo-fan), Propeller lift (tilt-wing and deflected slipstream), Jet flaps, and Boundary layer control (blowing and suction). Some of the work at Firms and Universities is also mentioned where the information has been made available for general circulation. Attention is drawn to the present state of knowledge in relation to V.T.O.L. and S.T.O.L. aircraft applications and to some major aerodynamic problems which need further study.
A spliceosome intermediate with loosely associated tri-snRNP accumulates in the absence of Prp28 ATPase activity
Authors: Boesler Carsten , Rigo Norbert , Anokhina Maria M. , Tauchert Marcel J. , Agafonov Dmitry E. , Kastner Berthold , Urlaub Henning , Ficner Ralf , Will Cindy L. , Lührmann Reinhard 
Published: July 2016

AbstractThe precise role of the spliceosomal DEAD-box protein Prp28 in higher eukaryotes remains unclear. We show that stable tri-snRNP association during pre-catalytic spliceosomal B complex formation is blocked by a dominant-negative hPrp28 mutant lacking ATPase activity. Complexes formed in the presence of ATPase-deficient hPrp28 represent a novel assembly intermediate, the pre-B complex, that contains U1, U2 and loosely associated tri-snRNP and is stalled before disruption of the U1/5′ss base pairing interaction, consistent with a role for hPrp28 in the latter. Pre-B and B complexes differ structurally, indicating that stable tri-snRNP integration is accompanied by substantial rearrangements in the spliceosome. Disruption of the U1/5′ss interaction alone is not sufficient to bypass the block by ATPase-deficient hPrp28, suggesting hPrp28 has an additional function at this stage of splicing. Our data provide new insights into the function of Prp28 in higher eukaryotes, and the requirements for stable tri-snRNP binding during B complex formation.
Genomics-informed isolation and characterization of a symbiotic Nanoarchaeota system from a terrestrial geothermal environment
Authors: Wurch Louie , Giannone Richard J. , Belisle Bernard S. , Swift Carolyn , Utturkar Sagar , Hettich Robert L. , Reysenbach Anna-Louise , Podar Mircea 
Published: July 2016

AbstractBiological features can be inferred, based on genomic data, for many microbial lineages that remain uncultured. However, cultivation is important for characterizing an organism’s physiology and testing its genome-encoded potential. Here we use single-cell genomics to infer cultivation conditions for the isolation of an ectosymbiotic Nanoarchaeota (‘Nanopusillus acidilobi’) and its host (Acidilobus, a crenarchaeote) from a terrestrial geothermal environment. The cells of ‘Nanopusillus’ are among the smallest known cellular organisms (100–300 nm). They appear to have a complete genetic information processing machinery, but lack almost all primary biosynthetic functions as well as respiration and ATP synthesis. Genomic and proteomic comparison with its distant relative, the marine Nanoarchaeum equitans illustrate an ancient, common evolutionary history of adaptation of the Nanoarchaeota to ectosymbiosis, so far unique among the Archaea.
Optimising, generalising and integrating educational practice using neuroscience
Authors: Colvin Robert 
Published: July 2016

AbstractPractical collaboration at the intersection of education and neuroscience research is difficult because the combined discipline encompasses both the activity of microscopic neurons and the complex social interactions of teachers and students in a classroom. Taking a pragmatic view, this paper discusses three education objectives to which neuroscience can be effectively applied: optimising, generalising and integrating instructional techniques. These objectives are characterised by: (1) being of practical importance; (2) building on existing education and cognitive research; and (3) being infeasible to address based on behavioural experiments alone. The focus of the neuroscientific aspect of collaborative research should be on the activity of the brain before, during and after learning a task, as opposed to performance of a task. The objectives are informed by literature that highlights possible pitfalls with educational neuroscience research, and are described with respect to the static and dynamic aspects of brain physiology that can be measured by current technology.
Chloroplast genome structure in Ilex (Aquifoliaceae)
Authors: Yao Xin , Tan Yun-Hong , Liu Ying-Ying , Song Yu , Yang Jun-Bo , Corlett Richard T. 
Published: July 2016

AbstractAquifoliaceae is the largest family in the campanulid order Aquifoliales. It consists of a single genus,Ilex, the hollies, which is the largest woody dioecious genus in the angiosperms. Most species are in East Asia or South America. The taxonomy and evolutionary history remain unclear due to the lack of a robust species-level phylogeny. We produced the first complete chloroplast genomes in this family, including sevenIlexspecies, by Illumina sequencing of long-range PCR products and subsequent reference-guidedde novoassembly. These genomes have a typical bicyclic structure with a conserved genome arrangement and moderate divergence. The total length is 157,741 bp and there is one large single-copy region (LSC) with 87,109 bp, one small single-copy with 18,436 bp, and a pair of inverted repeat regions (IR) with 52,196 bp. A total of 144 genes were identified, including 96 protein-coding genes, 40 tRNA and 8 rRNA. Thirty-four repetitive sequences were identified inIlex pubescens, with lengths >14 bp and identity >90%, and 11 divergence hotspot regions that could be targeted for phylogenetic markers. This study will contribute to improved resolution of deep branches of theIlexphylogeny and facilitate identification ofIlexspecies.
Proteome-wide measurement of non-canonical bacterial mistranslation by quantitative mass spectrometry of protein modifications
Authors: Cvetesic Nevena , Semanjski Maja , Soufi Boumediene , Krug Karsten , Gruic-Sovulj Ita , Macek Boris 
Published: July 2016

AbstractThe genetic code is virtually universal in biology and was likely established before the advent of cellular life. The extent to which mistranslation occurs is poorly understood and presents a fundamental question in basic research and production of recombinant proteins. Here we used shotgun proteomics combined with unbiased protein modification analysis to quantitatively analyze in vivo mistranslation in an E. coli strain with a defect in the editing mechanism of leucyl-tRNA synthetase. We detected the misincorporation of a non-proteinogenic amino acid norvaline on 10% of all measured leucine residues under microaerobic conditions and revealed preferential deployment of a tRNALeu(CAG) isoacceptor during norvaline misincorporation. The strain with the norvalylated proteome demonstrated a substantial reduction in cell fitness under both prolonged aerobic and microaerobic cultivation. Unlike norvaline, isoleucine did not substitute for leucine even under harsh error-prone conditions. Our study introduces shotgun proteomics as a powerful tool in quantitative analysis of mistranslation.
Purification of Logic-Qubit Entanglement
Authors: Zhou Lan , Sheng Yu-Bo 
Published: July 2016

AbstractRecently, the logic-qubit entanglement shows its potential application in future quantum communication and quantum network. However, the entanglement will suffer from the noise and decoherence. In this paper, we will investigate the first entanglement purification protocol for logic-qubit entanglement. We show that both the bit-flip error and phase-flip error in logic-qubit entanglement can be well purified. Moreover, the bit-flip error in physical-qubit entanglement can be completely corrected. The phase-flip in physical-qubit entanglement error equals to the bit-flip error in logic-qubit entanglement, which can also be purified. This entanglement purification protocol may provide some potential applications in future quantum communication and quantum network.
Germline viral “fossils” guide in silico reconstruction of a mid-Cenozoic era marsupial adeno-associated virus
Authors: Smith Richard H. , Hallwirth Claus V. , Westerman Michael , Hetherington Nicola A. , Tseng Yu-Shan , Cecchini Sylvain , Virag Tamas , Ziegler Mona-Larissa , Rogozin Igor B. , Koonin Eugene V. , Agbandje-McKenna Mavis , Kotin Robert M. , Alexander Ian E. 
Published: July 2016

AbstractGermline endogenous viral elements (EVEs) genetically preserve viral nucleotide sequences useful to the study of viral evolution, gene mutation, and the phylogenetic relationships among host organisms. Here, we describe a lineage-specific, adeno-associated virus (AAV)-derived endogenous viral element (mAAV-EVE1) found within the germline of numerous closely related marsupial species. Molecular screening of a marsupial DNA panel indicated that mAAV-EVE1 occurs specifically within the marsupial suborder Macropodiformes (present-day kangaroos, wallabies, and related macropodoids), to the exclusion of other Diprotodontian lineages. Orthologous mAAV-EVE1 locus sequences from sixteen macropodoid species, representing a speciation history spanning an estimated 30 million years, facilitated compilation of an inferred ancestral sequence that recapitulates the genome of an ancient marsupial AAV that circulated among Australian metatherian fauna sometime during the late Eocene to early Oligocene. In silico gene reconstruction and molecular modelling indicate remarkable conservation of viral structure over a geologic timescale. Characterisation of AAV-EVE loci among disparate species affords insight into AAV evolution and, in the case of macropodoid species, may offer an additional genetic basis for assignment of phylogenetic relationships among the Macropodoidea. From an applied perspective, the identified AAV “fossils” provide novel capsid sequences for use in translational research and clinical applications.
Mobility and subcellular localization of endogenous, gene-edited Tau differs from that of over-expressed human wild-type and P301L mutant Tau
Authors: Xia Di , Gutmann Julia M. , Götz Jürgen 
Published: July 2016

AbstractAlzheimer’s disease (AD) and a subset of frontotemporal dementia termed FTLD-Tau are characterized by a massive, yet incompletely characterized and understood redistribution of Tau. To establish a framework for understanding this pathology, we used the genome-editing tool TALEN and generated Tau-mEOS2 knock-in mice to determine the mobility and subcellular localization of endogenous Tau in hippocampal cultures. We analysed Tau in axons, dendrites and spines at three stages of maturation using live-cell imaging, photo-conversion and FRAP assays. Tau-mEOS2 cultures were compared with those over-expressing EGFP-tagged forms of human wild-type (hWT-Tau) and P301L mutant Tau (hP301L-Tau), modelling Tau accumulation in AD and FTLD-Tau, respectively. In developing neurons, Tau-mEOS2 followed a proximo-distal gradient in axons and a subcellular distribution similar to that of endogenous Tau in neurons obtained from wild-type mice, which were abolished, when either hWT-Tau or hP301L-Tau was over-expressed. For the three conditions, FRAP analysis revealed a similar mobility in dendrites compared with axons; however, Tau-mEOS2 was less mobile than hWT-Tau and hP301L-Tau and the mobile fraction was smaller, possibly reflecting less efficient microtubule binding of Tau when over-expressed. Together, our study presents Tau-mEOS2 mice as a novel tool for the study of Tau in a physiological and a pathological context.
Multiple CDK inhibitor dinaciclib suppresses neuroblastoma growth via inhibiting CDK2 and CDK9 activity
Authors: Chen Zhenghu , Wang Zhenyu , Pang Jonathan C. , Yu Yang , Bieerkehazhi Shayahati , Lu Jiaxiong , Hu Ting , Zhao Yanling , Xu Xin , Zhang Hong , Yi Joanna S. , Liu Shangfeng , Yang Jianhua 
Published: July 2016

AbstractNeuroblastoma (NB), the most common extracranial solid tumor of childhood, is responsible for approximately 15% of cancer-related mortality in children. Aberrant activation of cyclin-dependent kinases (CDKs) has been shown to contribute to tumor cell progression in many cancers including NB. Therefore, small molecule inhibitors of CDKs comprise a strategic option in cancer therapy. Here we show that a novel multiple-CDK inhibitor, dinaciclib (SCH727965, MK-7965), exhibits potent anti-proliferative effects on a panel of NB cell lines by blocking the activity of CDK2 and CDK9. Dinaciclib also significantly sensitized NB cell lines to the treatment of chemotherapeutic agents such as doxorubicin (Dox) and etoposide (VP-16). Furthermore, dinaciclib revealed in vivo antitumor efficacy in an orthotopic xenograft mouse model of two NB cell lines and blocked tumor development in the TH-MYCN transgenic NB mouse model. Taken together, this study suggests that CDK2 and CDK9 are potential therapeutic targets in NB and that abrogating CDK2 and CDK9 activity by small molecules like dinaciclib is a promising strategy and a treatment option for NB patients.