19,269 research outputs found
Experimental investigation of two nonaxisymmetric wedge nozzles at free stream Mach numbers up to 1.20
Forces and pressures on two nonaxisymmetric wedge nozzles were measured in a 16 foot transonic tunnel. Tests were conducted at static conditions and at free stream Mach numbers of 0.60, 0.80, 0.90, 0.94, and 1.20. The range of nozzle pressure ratios varied with configuration and Mach number. The internal and external geometry of the nozzles and the test model are defined in detail. Nozzle performance data are presented as discharge coefficients, internal thrust ratios, thrust minus nozzle drag ratios, and ideal thrust coefficients. Extensive internal and external pressure measurements are presented
A Reanalysis of the Carbon Abundance in the Translucent Cloud toward HD 24534
We have reanalyzed the Goddard High Resolution Spectrograph data set
presented by Snow et al. which contains the interstellar intersystem C II]
2325A line through the translucent cloud toward HD 24534 (X Persei). In
contrast to the results of Snow et al., we clearly detect the C II] feature at
the 3-sigma confidence level and measure a C^+ column density of 2.7 +/- 0.8 x
10^17 cm^-2. Accounting for the C I column density along the line of sight, we
find 10^6 C/H = 106 +/- 38 in the interstellar gas toward this star. This
gas-phase carbon-to-hydrogen ratio suggests that slightly more carbon depletion
may be occurring in translucent as compared to diffuse clouds. The average
diffuse-cloud C/H, however, is within the 1-sigma uncertainty of the
measurement toward HD 24534. We therefore cannot rule out the possibility that
the two cloud types have comparable gas-phase C/H, and therefore comparable
depletions of carbon.Comment: 9 pages, 3 figures, to appear in the Astrophysical Journal Letter
A New Template Family For The Detection Of Gravitational Waves From Comparable Mass Black Hole Binaries
In order to improve the phasing of the comparable-mass waveform as we
approach the last stable orbit for a system, various re-summation methods have
been used to improve the standard post-Newtonian waveforms. In this work we
present a new family of templates for the detection of gravitational waves from
the inspiral of two comparable-mass black hole binaries. These new adiabatic
templates are based on re-expressing the derivative of the binding energy and
the gravitational wave flux functions in terms of shifted Chebyshev
polynomials. The Chebyshev polynomials are a useful tool in numerical methods
as they display the fastest convergence of any of the orthogonal polynomials.
In this case they are also particularly useful as they eliminate one of the
features that plagues the post-Newtonian expansion. The Chebyshev binding
energy now has information at all post-Newtonian orders, compared to the
post-Newtonian templates which only have information at full integer orders. In
this work, we compare both the post-Newtonian and Chebyshev templates against a
fiducially exact waveform. This waveform is constructed from a hybrid method of
using the test-mass results combined with the mass dependent parts of the
post-Newtonian expansions for the binding energy and flux functions. Our
results show that the Chebyshev templates achieve extremely high fitting
factors at all PN orders and provide excellent parameter extraction. We also
show that this new template family has a faster Cauchy convergence, gives a
better prediction of the position of the Last Stable Orbit and in general
recovers higher Signal-to-Noise ratios than the post-Newtonian templates.Comment: Final published version. Accepted for publication in Phys. Rev.
Generarized Cubic Model for BaTiO-like Ferroelectric Substance
We propose an order-disorder type microscopic model for BaTiO-like
Ferroelectric Substance. Our model has three phase transitions and four phases.
The symmetry and directions of the polarizations of the ordered phases agree
with the experimental results of BaTiO. The intermediate phases in our
model are known as an incompletely ordered phase, which appears in a
generalized clock model.Comment: 6 pages, 4figure
A C-13(alpha,n)O-16 calibration source for KamLAND
We report on the construction and performance of a calibration source for
KamLAND using the reaction C-13(alpha,n)O-16 with Po-210 as the alpha
progenitor. The source provides a direct measurement of this background
reaction in our detector, high energy calibration points for the detector
energy scale, and data on quenching of the neutron visible energy in KamLAND
scintillator. We also discuss the possibility of using the reaction
C-13(alpha,n)O-16 as a source of tagged slow neutrons.Comment: 6 pages, 4 figures. Revised to agree with the published tex
Critical Role of FLRT1 Phosphorylation in the Interdependent Regulation of FLRT1 Function and FGF Receptor Signalling
Background
Fibronectin leucine rich transmembrane (FLRT) proteins have dual properties as regulators of cell adhesion and potentiators of fibroblast growth factor (FGF) mediated signalling. The mechanism by which the latter is achieved is still unknown and is the subject of this investigation.
Principal Findings
Here we show that FLRT1 is a target for tyrosine phosphorylation mediated by FGFR1 and implicate a non-receptor Src family kinase (SFK). We identify the target tyrosine residues in the cytoplasmic domain of FLRT1 and show that these are not direct substrates for Src kinase suggesting that the SFK may exert effects via potentiation of FGFR1 kinase activity. We show that whilst FLRT1 expression results in a ligand-dependent elevation of MAP kinase activity, a mutant version of FLRT1, defective as an FGFR1 kinase substrate (Y3F-FLRT1), has the property of eliciting ligand-independent chronic activation of the MAP kinase pathway which is suppressed by pharmacological inhibition of either FGFR1 or Src kinase. Functional investigation of FGFR1 and FLRT1 signalling in SH-SY5Y neuroblastoma cells reveals that FLRT1 alone acts to induce a multi-polar phenotype whereas the combination of FLRT1 and FGFR activation, or expression of Y3F-FLRT1, acts to induce neurite outgrowth via MAPK activation. Similar results were obtained in a dendrite outgrowth assay in primary hippocampal neurons. We also show that FGFR1, FLRT1 and activated Src are co-localized and this complex is trafficked toward the soma of the cell. The presence of Y3F-FLRT1 rather than FLRT1 resulted in prolonged localization of this complex within the neuritic arbour.
Conclusions
This study shows that the phosphorylation state of FLRT1, which is itself FGFR1 dependent, may play a critical role in the potentiation of FGFR1 signalling and may also depend on a SFK-dependent phosphorylation mechanism acting via the FGFR. This is consistent with an ‘in vivo’ role for FLRT1 regulation of FGF signalling via SFKs. Furthermore, the phosphorylation-dependent futile cycle mechanism controlling FGFR1 signalling is concurrently crucial for regulation of FLRT1-mediated neurite outgrowth
- …