4,328 research outputs found
Mechanically coupled laminates with balanced plain weave
Definitive listings of laminate stacking sequences are derived for balanced plain weave laminated materials, assuming each layer is composed of the same material with constant thickness throughout and that standard ply angle orientations 0, 90, and ±45° are adopted; consistent with industrial design practice. A single layer of balanced plain weave material is shown to be immune to thermal distortion following a standard high temperature manufacturing process, which implies that all laminates constructed of this material possess what is commonly referred to as the hygro-thermally curvature-stable or warp-free condition, irrespective of the individual ply orientations used or the laminate stacking sequence definition. A single uncoupled parent laminate class is shown to contain sub-groups with extensionally isotropic and fully isotropic properties that are invariant with off-axis orientation of the principal material axes with respect to the system or structural axes. By contrast a single mechanically coupled parent laminate class is shown to give rise to seven unique forms of coupled laminate through judicious off-axis orientation. Invariant off-axis properties are also identified in coupled laminate designs. Finally, example calculations, abridged stacking sequence listings and design data are presented
On the Observed W_MgII--L_[OII] Correlation in SDSS QSO Spectra
This paper investigates the effect of differential aperture loss with SDSS
fibers and examines whether such selection bias would result in the observed
correlation between rest-frame absorption equivalent width of MgII absorbers,
Wr(2796), and mean associated [OII] luminosity, L_[OII], in SDSS QSO spectra.
We demonstrate based on a Monte Carlo simulation that the observed Wr(2796) vs.
L_[OII] correlation of MgII absorbers can be well-reproduced, if all galaxies
found in deep surveys possess extended MgII halos and if the extent of MgII
halos scales proportionally with galaxy mass as shown in previous studies. The
observed correlation can be explained by a combination of (1) the known
Wr(2796) vs. rho anti-correlation in galaxy and MgII absorber pairs and (2) an
increasing aperture loss in the 3" diameter SDSS fiber for galaxies at larger
rho. Galaxies at larger projected distances produce on average weaker MgII
absorbers and weaker (or zero) L_[OII] in SDSS QSO spectra. We show that such
correlation diminishes when larger fibers are adopted and is therefore not
physical. While under a simple halo model the majority of MgII absorbers do not
directly probe star-forming disks, they trace photo-ionized halo gas associated
with galaxies. We show that because of the scaling relation between extended
gas cross-section and galaxy mass, the number density evolution of the MgII
absorber population as a whole provides a good measure of the cosmic star
formation history.Comment: 7 pages, 5 figures, accepted for publication in MNRA
Lignocellulose-based analytical devices: bamboo as an analytical platform for chemical detection
This article describes the development of lignocellulose-based analytical devices (LADs) for rapid bioanalysis in low-resource settings. LADs are constructed using either a single lignocellulose or a hybrid design consisting of multiple types of lignocellulose. LADs are simple, low-cost, easy to use, provide rapid response, and do not require external instrumentation during operation. Here, we demonstrate the implementation of LADs for food and water safety (i.e., nitrite assay in hot-pot soup, bacterial detection in water, and resazurin assay in milk) and urinalysis (i.e., nitrite, urobilinogen, and pH assays in human urine). Notably, we created a unique approach using simple chemicals to achieve sensitivity similar to that of commercially available immunochromatographic strips that is low-cost, and provides on-site, rapid detection, for instance, of Eschericia coli (E. coli) in water
What Determines the Incidence and Extent of MgII Absorbing Gas Around Galaxies?
We study the connections between on-going star formation, galaxy mass, and
extended halo gas, in order to distinguish between starburst-driven outflows
and infalling clouds that produce the majority of observed MgII absorbers at
large galactic radii (>~ 10 h^{-1} kpc) and to gain insights into halo gas
contents around galaxies. We present new measurements of total stellar mass
(M_star), H-alpha emission line strength (EW(H-alpha)), and specific star
formation rate (sSFR) for the 94 galaxies published in H.-W. Chen et al.
(2010). We find that the extent of MgII absorbing gas, R_MgII, scales with
M_star and sSFR, following R_MgII \propto M_star^{0.28}\times sSFR^{0.11}. The
strong dependence of R_MgII on M_star is most naturally explained, if more
massive galaxies possess more extended halos of cool gas and the observed MgII
absorbers arise in infalling clouds which will subsequently fuel star formation
in the galaxies. The additional scaling relation of R_MgII with sSFR can be
understood either as accounting for extra gas supplies due to starburst
outflows or as correcting for suppressed cool gas content in high-mass halos.
The latter is motivated by the well-known sSFR--M_star} inverse correlation in
field galaxies. Our analysis shows that a joint study of galaxies and MgII
absorbers along common sightlines provides an empirical characterization of
halo gaseous radius versus halo mass. A comparison study of R_MgII around red-
and blue-sequence galaxies may provide the first empirical constraint for
resolving the physical origin of the observed sSFR--M_star} relation in
galaxies.Comment: 6 pages, 3 figures; ApJL in pres
Conceptualizing a mobile-assisted learning environment featuring funds of knowledge for English learnersâ narrative writing development
The purpose of this exploratory sequential mixed-methods study is to investigate a group of middle-school aged Latinx English learners (ELs) in a rural town in the Midwestern United States and to facilitate their narrative writing development via a mobile-assisted language learning (MALL) environment from a funds of knowledge perspective. In particular, we first explored the existing funds of knowledge sources drawing from the ELsâ lived experience and cultural practice through a multimethodological approach over a span of three months. We conceptualized the explored funds of knowledge sources into ELsâ narrative writing practice through the integration of mobile-based writing tools (MBWTs). Second, we employed a multiple pre-and post- non-experimental design for the ELs to complete two non- funds of knowledge and three funds of knowledge-featured narrative writing activities over ten weeks using Google Docs as an MBWT. Results showed a statistically significant positive learning effect of funds of knowledge as an intervention for developing the ELsâ literacy skills in narrative writing within a collaborative MALL environment
Searching for Dust Reddening in SDSS Spectra with Damped Lyman {} Systems
We searched for evidence of reddening of background SDSS QSO spectra due to
dust in intervening DLA systems. We utilise the Data Releases 5 and 7 to arrive
at sample sizes of 475 (DR5) and 676 (DR7) absorbers, based on two different
published lists of SDSS DLAs. Both samples span roughly the redshift range of
2.2 < z_abs < 5.2, with a mean of z~3.0, and the majority of the DLAs (75%)
below z=3.3. We construct geometric mean spectra in the absorber restframes
ranging from 1240 to ~2800 A, and composite spectra of samples matching the
'DLA' QSOs in i band magnitude and emission redshift z_em, but without
absorption lines. By comparing the slopes of these composite spectra with their
matched counterparts, we find no sign of reddening in the ensemble of the
absorbers from these samples. Owing to both the unprecedently large sizes of
the DLA samples themselves and the non-DLA SDSS QSO sample, from which we can
draw our matching spectra, we can place very tight limits for this
non-detection ( =-0.0013+-0.0025 (DR5) and =-0.0017+-0.0022
(DR7). Interestingly, when applying our technique to the samples of York et.
al. (2006), vandenBerk et al. (2008) (intervening and intrinsic MgII absorbers)
and the smaller DLA-subsample and pool of comparison QSOs of Vladilo et al.
(2008), we do recover their results, i.e. detect the same amount of reddening
as these authors do. Furthermore, we have tested whether subsamples of our
large sample in categories involving the absorbers (HI column densities,
presence or absence of accompanying metal absorption, absorber redshift) or the
background quasars (emission redshift, brightness) do reveal dust extinction,
but found no trends. These results are at odds with both detections of dust
reddening from previous studies, and also with expectations from observations
of high-redshift galaxies. (abridged)Comment: 16 pages, 12 figures, accepted for publication in MNRA
The Lack of Torus Emission from BL Lacertae Objects: An Infrared View of Unification with WISE
We use data from the Wide-Field Infrared Survey Explorer (WISE) to perform a
statistical study on the mid-infrared (IR) properties of a large number
() of BL Lac objects --- low-luminosity Active Galactic Nuclei (AGN)
with a jet beamed toward the Earth. As expected, many BL Lac objects are so
highly beamed that their jet synchrotron emission dominates their IR spectral
energy distributions. In other BL Lac objects, however, the jet is not strong
enough to completely dilute the rest of the AGN emission. We do not see
observational signatures of the dusty torus from these weakly beamed BL Lac
objects. The lack of observable torus emission is consistent with suggestions
that BL Lac objects are fed by radiatively inefficient accretion disks.
Implications for the "nature vs. nurture" debate for FR I and FR II radio
galaxies are briefly discussed. Our study supports the notion that, beyond
orientation, accretion rate plays an important role in AGN unification.Comment: 6 Pages, 3 Figures, accepted for publication in ApJ Letter
The Information Of The Milky Way From 2MASS Whole Sky Star Count: The Bimodal Color Distributions
The J-Ks color distribution (CD) with a bin size of 0.05 magnitude for the
entire Milky Way has been carried out by using the Two Micron All Sky Survey
Point Source Catalog (2MASS PSC). The CDs are bimodal, which has a red peak at
0.8 < J-Ks < 0.85 and a blue peak at 0.3 < J-Ks < 0.4. The colors of the red
peak are more or less the same for the whole sky, but that of the blue peak
depend on Galactic latitude, (J-Ks ~ 0.35 at low Galactic latitudes and 0.35 <
J-Ks < 0.4 for other sky areas). The blue peak dominates the bimodal CDs at low
Galactic latitudes and becomes comparable with the red peak in other sky
regions. In order to explain the bimodal distribution and the global trend
shown by the all sky 2MASS CDs, we assemble an empirical HR diagram, which is
composed by observational-based near infrared HR diagrams and color magnitude
diagrams, and incorporate a Milky Way model. In the empirical HR diagram, the
main sequence stars turnoff the thin disk is relatively bluer, (J-Ks)0 = 0.31,
when we compare with the thick disk which is (J-Ks)0 = 0.39. The age of the
thin/thick disk is roughly estimated to be around 4-5/8-9 Gyr according to the
color-age relation of the main sequence turnoff. In general, the 2MASS CDs can
be treated as a tool to census the age of stellar population of the Milky Way
in a statistical manner and to our knowledge this is a first attempt to measure
the age.Comment: Accepted by ApJ on Sept. 11 201
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Oral Cytokine Levels Are More Linked to Levels of Plasma and Oral HIV-1 RNA Than to CD4+ T-Cell Counts in People With HIV.
BackgroundWe determined the levels of 11 soluble immune mediators in oral washings of AIDS Clinical Trials Group A5254 participants with varying degrees of plasma viremia and CD4 T-cell counts to characterize the mucosal immune response at different stages of HIV-1 infection.MethodsA5254 was a multicenter, cross-sectional study in people with HIV (PWH) recruited into 4 strata based on CD4 count and levels of plasma viremia: stratum (St) A: CD4 â€200 cells/mm3, HIV-1 RNA (viral load [VL]) >1000 cps/mL; St B: CD4 â€200, VL â€1000; St C: CD4 >200, VL >1000; St D: CD4 >200, VL â€1000. Oral/throat washings were obtained from all participants. Soluble markers were tested in oral/throat washings using a multibead fluorescent platform and were compared across strata. Linear regression was used to determine the associations between cytokines and HIV-1 in plasma and oral fluid.ResultsSt A participants had higher levels of interleukin (IL)-1ÎČ, IL-6, IL-17, tumor necrosis factor alpha (TNFα), and interferon gamma (IFNÎł) compared with St B and D (P = .02; P < .0001) but were not different from St C. IL-8, IL-10, and IL-12 were elevated in St A compared with the other 3 strata (P = .046; P < .0001). Linear regression demonstrated that oral HIV-1 levels were associated with IL-1ÎČ, IL-6, IL-8, and TNFα production (R > .40; P < .001) when controlling for CD4 count and opportunistic infections.ConclusionsOur results show that high levels of oral HIV-1, rather than low CD4 counts, were linked to the production of oral immune mediators. Participants with AIDS and uncontrolled viremia demonstrated higher levels of pro- and anti-inflammatory soluble immune mediators compared with participants with lower HIV-1 RNA. The interplay of HIV-1 and these immune mediators could be important in the oral health of PWH
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