Information retrieval system

Generalized information storage and retrieval system capable of generating and maintaining a file, gathering statistics, sorting output, and generating final reports for output is reviewed. File generation and file maintenance programs written for the system are general purpose routines

Scramjets and Shock Tunnels: The Queensland Experience

This article reports on the use of a shock tunnel to study the operation of scramjet powered configurations at sub-orbital velocities above 2 km/s. Thrust, as given by a net thrust equation, is used as a figure of merit throughout the study. After a short description of the shock tunnel used and its operating characteristics, experiments on the combustion release of heat in a constant area duct with hydrogen fuel are reviewed. The interaction between heat release in the combustion wake and the walls of the duct produced pressure distributions which followed a binary scaling law, and indicated that the theoretically expected heat release could be realized in practice, albeit with high pressure or long combustion ducts. This heat release, combined with attainable thrust nozzle characteristics and a modest level of configuration drag, indicated that positive thrust levels could be obtained well into the sub-orbital range of velocities. Development of a stress wave force balance for use in shock tunnels allowed the net thrust generated to be measured for integrated scramjet configurations and, although the combination of model size and shock tunnel operating pressure prevented complete combustion of hydrogen, the cruise condition of zero net thrust was achieved at 2.5 km/s with one configuration, while net thrust was produced with another configuration using an ignition promoter in hydrogen fuel. Nevertheless, the combination of boundary layer separation induced inlet choking and limited operating pressure levels prevented realization of the thrust potential of the fuel. This problem may be alleviated by recent increases in the shock tunnel operating pressures, and by promising research involving inlet injection of the fuel. Research on the drag component of the net thrust equation resulted from the development of a fast response skin friction gauge. It was found that existing theories of turbulent boundary skin friction predicted the skin friction when combustion of hydrogen occurred outside the boundary layer, but combustion within the boundary layer dramatically reduced the skin friction. Finally, for the first time in the world, supersonic combustion was produced in a free flight experiment. This experiment validated shock tunnel results at stagnation enthalpies near 3 MJ/k

Simulation of the Performance of the IISc Chemical Kinetics Shock Tube

This report presents the results of an investigation of the performance of the Chemical Kinetics Shock tube at the Indian Institute of Science. The one-dimensional Lagrangian code L1d of Jacobs (1998) has been used to simulate the tube at several operating conditions. The conditions have different shock tube filling pressures, resulting in different shock speeds and different tube lengths, resulting in different dwell times. The simulations have been performed both with and without viscous effects simulated in the tubes. At the lowest shock tube filling pressure condition, the shock tube operates in an overtailored mode and it is undertailored at the higher filling pressure conditions. The results show that viscous effects, which lead to attenuation of the primary shock and heat loss from the test gas to the tube walls, result in an increasing p5 pressure during the test time. The viscous effects are more dominant at the condition with the lowest filling pressure (highest primary shock speed). A simulation run for 50 ms after diaphragm rupture or the configuration with a long driver tube shows that the test gas is periodically re-compressed by reflections of waves along the driver and shock tubes. The recompressions become sequentially weaker and thus the test gas temperature and pressure are never raised to as high levels as for the primary compression

Mapping giant magnetic fields around dense solid plasmas by high resolution magneto-optical microscopy

We investigate distribution of magnetic fields around dense solid plasmas generated by intense p-polarized laser (~10^{16} W.cm^{-2}, 100 fs) irradiation of magnetic tapes, using high sensitivity magneto optical microscopy. We present evidence for giant axial magnetic fields and map out for the first time the spatial distribution of these fields. By using the axial magnetic field distribution as a diagnostic tool we uncover evidence for angular momentum associated with the plasma. We believe this study holds significance for investigating the process under which a magnetic material magnetizes or demagnetizes under the influence of ultrashort intense laser pulses.Comment: 17 pages of text with 4 figure

Polarization restricts hepatitis C virus entry into HepG2 hepatoma cells

The primary reservoir for hepatitis C virus (HCV) replication is believed to be hepatocytes, which are highly polarized with tight junctions (TJ) separating their basolateral and apical domains. HepG2 cells develop polarity over time, resulting in the formation and remodeling of bile canalicular (BC) structures. HepG2 cells expressing CD81 provide a model system to study the effects of hepatic polarity on HCV infection. We found an inverse association between HepG2-CD81 polarization and HCV pseudoparticle entry. As HepG2 cells polarize, discrete pools of claudin-1 (CLDN1) at the TJ and basal/lateral membranes develop, consistent with the pattern of receptor staining observed in liver tissue. The TJ and nonjunctional pools of CLDN1 show an altered association with CD81 and localization in response to the PKA antagonist Rp-8-Br-cyclic AMPs (cAMPs). Rp-8-Br-cAMPs reduced CLDN1 expression at the basal membrane and inhibited HCV infection, supporting a model where the nonjunctional pools of CLDN1 have a role in HCV entry. Treatment of HepG2 cells with proinflammatory cytokines, tumor necrosis factor alpha and gamma interferon, perturbed TJ integrity but had minimal effect(s) on cellular polarity and HCV infection, suggesting that TJ integrity does not limit HCV entry into polarized HepG2 cells. In contrast, activation of PKC with phorbol ester reduced TJ integrity, ablated HepG2 polarity, and stimulated HCV entry. Overall, these data show that complex hepatocyte-like polarity alters CLDN1 localization and limits HCV entry, suggesting that agents which disrupt hepatocyte polarity may promote HCV infection and transmission within the liver

Magnetic field generation by coherent turbulence structures

It is thought that the small-scale magnetic fields observed in accretion discs, galaxies and galactic clusters are generated by a dynamo process in which the turbulent plasma amplifies small initial magnetic fluctuations. Numerical simulations of turbulence have revealed that turbulence consists of filamentlike vortex structures superimposed on an incoherent background, which carry a considerable amount of the energy. The natural questions to ask are whether these coherent structures can generate a magnetic field and, if so, if the generated magnetic field is also filament-like. After setting up a turbulence model which consists only of vortex filaments, we show in an unambiguous way that the coherent structure can sustain kinematic dynamo action and that the magnetic field thus generated consists of relatively thick ribbons (flattened tubes) located in between vortices

Explicit solutions to the Korteweg-de Vries equation on the half line

Certain explicit solutions to the Korteweg-de Vries equation in the first quadrant of the $xt$-plane are presented. Such solutions involve algebraic combinations of truly elementary functions, and their initial values correspond to rational reflection coefficients in the associated Schr\"odinger equation. In the reflectionless case such solutions reduce to pure $N$-soliton solutions. An illustrative example is provided.Comment: 17 pages, no figure

The homeobox transcription factor Even-skipped regulates acquisition of electrical properties in Drosophila neurons.

BACKGROUND: While developmental processes such as axon pathfinding and synapse formation have been characterized in detail, comparatively less is known of the intrinsic developmental mechanisms that regulate transcription of ion channel genes in embryonic neurons. Early decisions, including motoneuron axon targeting, are orchestrated by a cohort of transcription factors that act together in a combinatorial manner. These transcription factors include Even-skipped (Eve), islet and Lim3. The perdurance of these factors in late embryonic neurons is, however, indicative that they might also regulate additional aspects of neuron development, including the acquisition of electrical properties. RESULTS: To test the hypothesis that a combinatorial code transcription factor is also able to influence the acquisition of electrical properties in embryonic neurons we utilized the molecular genetics of Drosophila to manipulate the expression of Eve in identified motoneurons. We show that increasing expression of this transcription factor, in two Eve-positive motoneurons (aCC and RP2), is indeed sufficient to affect the electrical properties of these neurons in early first instar larvae. Specifically, we observed a decrease in both the fast K+ conductance (IKfast) and amplitude of quantal cholinergic synaptic input. We used charybdotoxin to pharmacologically separate the individual components of IKfast to show that increased Eve specifically down regulates the Slowpoke (a BK Ca2+-gated potassium channel), but not Shal, component of this current. Identification of target genes for Eve, using DNA adenine methyltransferase identification, revealed strong binding sites in slowpoke and nAcRalpha-96Aa (a nicotinic acetylcholine receptor subunit). Verification using real-time PCR shows that pan-neuronal expression of eve is sufficient to repress transcripts for both slo and nAcRalpha-96Aa. CONCLUSION: Taken together, our findings demonstrate, for the first time, that Eve is sufficient to regulate both voltage- and ligand-gated currents in motoneurons, extending its known repertoire of action beyond its already characterized role in axon guidance. Our data are also consistent with a common developmental program that utilizes a defined set of transcription factors to determine both morphological and functional neuronal properties

Exact solutions to the focusing nonlinear Schrodinger equation

A method is given to construct globally analytic (in space and time) exact solutions to the focusing cubic nonlinear Schrodinger equation on the line. An explicit formula and its equivalents are presented to express such exact solutions in a compact form in terms of matrix exponentials. Such exact solutions can alternatively be written explicitly as algebraic combinations of exponential, trigonometric, and polynomial functions of the spatial and temporal coordinates.Comment: 60 pages, 18 figure

Real world challenges in delivering person centred care: A community based case study

Community nurses face many challenges when trying to practice evidence-based, person-centred care. Ongoing concerns regarding the impact of the 2013 Francis Report (Ford and Lintern, 2017) suggest that individualised and holistic care is an impossible dream, one made harder when the client appears uncooperative. This paper presents a case study that sets out how some of these challenges were met in a potentially difficult situation experienced by a student nurse and her mentor in practice, in which the student was supported to further examine and explore issues that may have influenced the situation. In this instance, the solution came with the recognition that the client had expertise and knowledge that needed to be taken into account, alongside that of the nurses looking after him. His care became a partnership, not an imposition of expertise; a principle which is transferable to many other situations. Underpinning it was the recognition of our shared humanity, wherein lies the essence of truly holistic care, and student nurses learning this, through the guidance and support of their mentor.