A test facility for hypervelocity rarefied flows

This paper describes a rarefied hypervelocity test facility producing gas speeds greater than 7 km/s. The X1 expansion tube at the University of Queensland has been used to produce nitrogen flows at 8.9 and 9.5 km/s with test flow durations of 50 and 40 microsecond­s respectively. Rarefied flow is indicated by values of the freestream breakdown parameter > 0.1 (Cheng's rarefaction parameter < 10) and freestream Knudsen numbers up to 0.038, based on a model size of 9 mm. To achieve this, the test gas is expanded from the end of the acceleration tube into a dump tank. Nominal conditions in the expansion are derived from CFD predictions. Measured bar gauge (Pitot) pressures show that the flow is radially uniform when the Pitot pressure has decreased by a factor ten. The measured bar gauge pressures are an increasing fraction of the expected Pitot pressure as the rarefaction parameters increase

Strong interaction of a turbulent spot with a shock-induced separation bubble

Direct numerical simulations have been conducted to study the passage of a turbulent spot through a shock-induced separation bubble. Localized blowing is used to trip the boundary layer well upstream of the shock impingement, leading to mature turbulent spots at impingement, with a length comparable to the length of the separation zone. Interactions are simulated at free stream Mach numbers of two and four, for isothermal (hot) wall boundary conditions. The core of the spot is seen to tunnel through the separation bubble, leading to a transient reattachment of the flow. Recovery times are long due to the influence of the calmed region behind the spot. The propagation speed of the trailing interface of the spot decreases during the interaction and a substantial increase in the lateral spreading of the spot was observed. A conceptual model based on the growth of the lateral shear layer near the wingtips of the spot is used to explain the change in lateral growth rat

Investigation of single crystal ferrite thin films

Materials suitable for use in magnetic bubble domain memories were developed for aerospace applications. Practical techniques for the preparation of such materials in forms required for fabrication of computer memory devices were considered. The materials studied were epitaxial films of various compositions of the gallium-substituted yttrium gadolinium iron garnet system. The major emphasis was to determine their bubble properties and the conditions necessary for growing uncracked, high quality films

Clinical measurement of dart throwing motion of the wrist: variability, accuracy and correction

Despite being functionally important, dart throwing motion is difficult to assess accurately through goniometry. The objectives of this study were to describe a method for reliably quantifying the dart throwing motion using goniometric measurements within a healthy population. Wrist kinematics of 24 healthy participants were assessed using goniometry and optical motion tracking. Three wrist angles were measured at the starting and ending points of the motion: flexion-extension, radial-ulnar deviation and dart throwing motion angle. The orientation of the dart throwing motionplane relative to the flexion-extension axis ranged between 28° and 57° among the tested population. Plane orientations derived from optical motion capture differed from those calculated through goniometry by 25°. An equation to correct the estimation of the plane from goniometry measurements was derived. This was applied and differences in the orientation of the plane were reduced to non-significant levels, enabling dart throwing motion to be measured using goniometry alone

CD81 and claudin 1 coreceptor association: role in hepatitis C virus entry.

Hepatitis C virus (HCV) is an enveloped positive-stranded RNA hepatotropic virus. HCV pseudoparticles infect liver-derived cells, supporting a model in which liver-specific molecules define HCV internalization. Three host cell molecules have been reported to be important entry factors or receptors for HCV internalization: scavenger receptor BI, the tetraspanin CD81, and the tight junction protein claudin-1 (CLDN1). None of the receptors are uniquely expressed within the liver, leading us to hypothesize that their organization within hepatocytes may explain receptor activity. Since CD81 and CLDN1 act as coreceptors during late stages in the entry process, we investigated their association in a variety of cell lines and human liver tissue. Imaging techniques that take advantage of fluorescence resonance energy transfer (FRET) to study protein-protein interactions have been developed. Aequorea coerulescens green fluorescent protein- and Discosoma sp. red-monomer fluorescent protein-tagged forms of CD81 and CLDN1 colocalized, and FRET occurred between the tagged coreceptors at comparable frequencies in permissive and nonpermissive cells, consistent with the formation of coreceptor complexes. FRET occurred between antibodies specific for CD81 and CLDN1 bound to human liver tissue, suggesting the presence of coreceptor complexes in liver tissue. HCV infection and treatment of Huh-7.5 cells with recombinant HCV E1-E2 glycoproteins and anti-CD81 monoclonal antibody modulated homotypic (CD81-CD81) and heterotypic (CD81-CLDN1) coreceptor protein association(s) at specific cellular locations, suggesting distinct roles in the viral entry process

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

Autoantibody detection for diagnosis in direct immunofluorescence negative mucous membrane pemphigoid: ocular and other sites compared

Objective: To assess whether a panel of serum pemphigoid autoantibody tests could be used to confirm an immunopathological diagnosis of mucous membrane pemphigoid (MMP) in direct immunofluorescent negative (DIF-) MMP patients. / Design: Prospective cross-sectional study. / Subjects and controls: 76 patients with MMP involving ocular and non-ocular sites with 45 matched controls. / Tests: Enzyme linked immunosorbent assays (ELISA) for BP180 and BP230 (MBL International®), IgA and IgG indirect immunofluorescence on human salt-split skin (IIF SSS) and the keratinocyte footprint assay for anti-laminin 332 antibodies. / Main outcome measures: Sensitivity and specificity of autoantibody detection; significant differences for individual tests and test combinations for MMP involving different sites. / Results: All DIF- Cases (24/76, 31.8%) had either ocular only disease or ocular involvement in multi-site disease. Serum pemphigoid autoantibodies were detected in 29/76 (38.2%) of all MMP patients compared to 3/45 (6.7%) of controls. Autoantibody reactivity detected by any one or more of the tests was present in 6/24 (25%) DIF- cases compared to 22/49 (44.9%) in DIF positive (DIF+). Compared to controls ocular only MMP serum reactivity was not significantly different for any test or test combination whereas DIF- multisite ocular MMP differed for one ELISA and 3/7 test combinations. By contrast, for DIF+ non ocular MMP all the individual tests, apart from IgA IIF, and all test combinations were significantly different compared to controls. For the whole MMP cohort the sensitivity of all tests was low having a maximum of 21.05% for BP180 reactivity, increasing to 38.16% for an optimal test combination. Disease activity was strongly associated with positive serology findings. / Conclusions: Pemphigoid serum autoantibody tests did not provide alternative immunopathological evidence of MMP in ocular only MMP patients but had limited value in DIF- multisite ocular MMP. The requirement for immunopathological confirmation of MMP by autoantibody detection is inappropriate for DIF- ocular only MMP resulting in missed diagnoses, delayed therapy and poor outcomes. Alternative diagnostic criteria for MMP with ocular involvement are required, to exclude the other causes of scarring conjunctivitis, until more sensitive and specific immunopathology tests become available

Cyclic-AMP regulates postnatal development of neural and behavioral responses to NaCl in rats

During postnatal development rats demonstrate an age-dependent increase in NaCl chorda tympani (CT) responses and the number of functional apical amiloride-sensitive epithelial Na+channels (ENaCs) in salt sensing fungiform (FF) taste receptor cells (TRCs). Currently, the intracellular signals that regulate the postnatal development of salt taste have not been identified. We investigated the effect of cAMP, a downstream signal for arginine vasopressin (AVP) action, on the postnatal development of NaCl responses in 19–23 day old rats. ENaC-dependent NaCl CT responses were monitored after lingual application of 8-chlorophenylthio-cAMP (8-CPT-cAMP) under open-circuit conditions and under ±60 mV lingual voltage clamp. Behavioral responses were tested using 2 bottle/24h NaCl preference tests. The effect of [deamino-Cys1, D-Arg8]-vasopressin (dDAVP, a specific V2R agonist) was investigated on ENaC subunit trafficking in rat FF TRCs and on cAMP generation in cultured adult human FF taste cells (HBO cells). Our results show that in 19–23 day old rats, the ENaC-dependent maximum NaCl CT response was a saturating sigmoidal function of 8-CPT-cAMP concentration. 8-CPT-cAMP increased the voltage-sensitivity of the NaCl CT response and the apical Na+ response conductance. Intravenous injections of dDAVP increased ENaC expression and γ-ENaC trafficking from cytosolic compartment to the apical compartment in rat FF TRCs. In HBO cells dDAVP increased intracellular cAMP and cAMP increased trafficking of γ- and δ-ENaC from cytosolic compartment to the apical compartment 10 min post-cAMP treatment. Control 19–23 day old rats were indifferent to NaCl, but showed clear preference for appetitive NaCl concentrations after 8-CPT-cAMP treatment. Relative to adult rats, 14 day old rats demonstrated significantly less V2R antibody binding in circumvallate TRCs. We conclude that an age-dependent increase in V2R expression produces an AVP-induced incremental increase in cAMP that modulates the postnatal increase in TRC ENaC and the neural and behavioral responses to NaCl