2,830 research outputs found
Novel method for measuring induction rates
This paper introduces a new technique for measuring induction ratios for different nozzle and combined flow geometries. The measurement technique only requires a single point velocity measurement in the secondary air inflow and a static pressure measurement in the primary air
chamber. The design if the device allows the induction ratio to be determined for different primary air nozzle arrangements with different geometries for combined air discharge outlets.
Experimentally measured data is compared with theoretical values. Four different sized circular nozzles with different outlet geometries were used to supply primary air into the device. The outlet geometries consisted of circular, slot and a rectangular shape. The results
showed that the outlet geometry has very little or no effect on the induction ratio. The most important parameter in the induction ratio is the area ratio of the nozzle and the outlet
CFD validation of the thermal comfort in a room using draft rates
Air temperature and velocity are the two main factors affecting the thermal comfort indoors. These two values can be easily obtained using computational fluid dynamic (CFD) simulations together with the turbulence kinetic energy value. This paper evaluates methods of calculating thermal comfort indices using CFD. Simulated results are compared against experimental data measured in a purpose build full-scale model room. The results show that CFD data can reliably predict thermal comfort values
Chaucer\u27s use of figures of comparison in the canterbury tales
The purpose of this thesis is to analyze the unity of style and imagery in the Canterbury Tales. It attempts to prove that Chaucer emplys three figures of comparison - simile, imago, and metaphor - in a consistent manner throughout the work to suit the narrative purpose of each tale and the preponderance of natural imagery in the comparisons provides a connecting link among the various tales, prologues, and epilogues
Where do "red and dead" early-type void galaxies come from?
Void regions of the Universe offer a special environment for studying
cosmology and galaxy formation, which may expose weaknesses in our
understanding of these phenomena. Although galaxies in voids are observed to be
predominately gas rich, star forming and blue, a sub-population of bright red
void galaxies can also be found, whose star formation was shut down long ago.
Are the same processes that quench star formation in denser regions of the
Universe also at work in voids?
We compare the luminosity function of void galaxies in the 2dF Galaxy
Redshift Survey, to those from a galaxy formation model built on the Millennium
Simulation. We show that a global star formation suppression mechanism in the
form of low luminosity "radio mode" AGN heating is sufficient to reproduce the
observed population of void early-types. Radio mode heating is environment
independent other than its dependence on dark matter halo mass, where, above a
critical mass threshold of approximately M_vir~10^12.5 M_sun, gas cooling onto
the galaxy is suppressed and star formation subsequently fades. In the
Millennium Simulation, the void halo mass function is shifted with respect to
denser environments, but still maintains a high mass tail above this critical
threshold. In such void halos, radio mode heating remains efficient and red
galaxies are found; collectively these galaxies match the observed space
density without any modification to the model. Consequently, galaxies living in
vastly different large-scale environments but hosted by halos of similar mass
are predicted to have similar properties, consistent with observations.Comment: 6 pages, 3 figures, accepted MNRA
Mucosal Immunization with a \u3cem\u3eStaphylococcus aureus\u3c/em\u3e IsdA-Cholera Toxin A\u3csub\u3e2\u3c/sub\u3e/B Chimera Induces Antigen-Specific Th2-Type Responses in Mice
Staphylococcus aureus is a leading cause of opportunistic infection worldwide and a significant public health threat. The iron-regulated surface determinant A (IsdA) adhesin is essential for S. aureus colonization on human nasal epithelial cells and plays an important role in iron acquisition and resistance to human skin defenses. Here we investigated the murine immune response to intranasal administration of a cholera toxin (CT) A2/B chimera containing IsdA. Plasmids were constructed to express the IsdA-CTA2/B chimera and control proteins in E. coli. Proper construction of the chimera was verified by SDS-PAGE, western blot, GM1 ELISA, and confocal microscopy. Groups of female BALB/c mice were immunized with IsdA-CTA2/B, IsdA mixed with CTA2/B, IsdA alone, or mock, followed by one booster immunization 10 days post-priming. Analysis of serum IgG and nasal, intestinal, and vaginal IgA suggested that mucosal immunization with IsdA-CTA2/B induces significant IsdA-specific humoral immunity. Functional in vitro assays revealed that α-IsdA immune serum significantly blocks the adherence of S. aureus to human epithelial cells. Splenocytes from mice immunized with IsdA-CTA2/B showed specific cellular proliferation and production of IL-4 after in vitro stimulation. Immunization with IsdA-CTA2/B drove isotype switching to IgG1, indicative of a Th2-type response. Our results suggest that the immunogenicity of the S. aureus IsdA-CTA2/B chimera merits further investigation as a potential mucosal vaccine candidate
The cosmology dependence of weak lensing cluster counts
We present the main results of a numerical study of weak lensing cluster
counting. We examine the scaling with cosmology of the projected-density-peak
mass function. Our main conclusion is that the projected-peak and the
three-dimensional mass functions scale with cosmology in an astonishingly close
way. This means that, despite being derived from a two-dimensional field, the
weak lensing cluster abundance can be used to constrain cosmology in the same
way as the three-dimensional mass function probed by other types of surveys.Comment: 4 pages, 2 figures. Accepted for publication in ApJL. Figure 1
modified, unchanged conclusion
From Galaxy-Galaxy Lensing to Cosmological Parameters
Galaxy-galaxy lensing measures the mean excess surface density DS(r) around a
sample of lensing galaxies. We develop a method for combining DS(r) with the
galaxy correlation function xi_gg(r) to constrain Omega_m and sigma_8, going
beyond the linear bias model to reach the level of accuracy demanded by current
and future measurements. We adopt the halo occupation distribution (HOD)
framework, and we test its applicability to this problem by examining the
effects of replacing satellite galaxies in the halos of an SPH simulation with
randomly selected dark matter particles from the same halos. The difference
between dark matter and satellite galaxy radial profiles has a ~10% effect on
DS(r) at r<1 Mpc/h. However, if radial profiles are matched, the remaining
impact of individual subhalos around satellite galaxies and environmental
dependence of the HOD at fixed halo mass is <5% in DS(r) for 0.1<r<15 Mpc/h. We
develop an analytic approximation for DS(r) that incorporates halo exclusion
and scale-dependent halo bias, and we demonstrate its accuracy with tests
against a suite of populated N-body simulations. We use the analytic model to
investigate the dependence of DS(r) and the galaxy-matter correlation function
xi_gm(r) on Omega_m and sigma_8, once HOD parameters for a given cosmological
model are pinned down by matching xi_gg(r). The linear bias prediction is
accurate for r>2 Mpc/h, but it fails at the 30-50% level on smaller scales. The
scaling of DS(r) ~ Omega_m^a(r) sigma_8^b(r) approaches the linear bias
expectation a=b=1 at r>10 Mpc/h, but a(r) and b(r) vary from 0.8 to 1.6 at
smaller r. We calculate a fiducial DS(r) and scaling indices a(r) and b(r) for
two SDSS galaxy samples; galaxy-galaxy lensing measurements for these samples
can be combined with our predictions to constrain Omega_m and sigma_8.Comment: 18 pages, 10 figures, accepted for publication in The Astrophysical
Journa
Initial investigations into the damping characteristics of wire rope vibration isolators
Passive dampers composed of coils of multi-strand wire rope are investigated. Analytical results range from those produced by complex NASTRAN models to those of a Coulomb damping model with variable friction force. The latter agrees well with experiment. The Coulomb model is also utilized to generate hysteresis loops. Various other models related to early experimental investigations are described. Significant closed-form static solutions for physical properties of single-and multi-strand wire ropes are developed for certain specific geometries and loading conditions. NASTRAN models concentrate on model generation and mode shapes of 2-strand and 7-strand straight wire ropes with interfacial forces
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