2,434 research outputs found
Mathematical Model and Performance Analysis of a Liquid Desiccant Dehumidification Tower
A finite difference model simulating a liquid desiccant dehumidification tower with lithium chloride as the desiccant solution has been developed. The model determines the packing height needed for a condensation rate. Comparisons with experimental data illustrates that the model produces valid results. Air and desiccant solution temperatures within the dehumidification tower show that a temperature increase is experienced for both the air and desiccant solution from their respective entrances and exits from the tower. Increasing the air mass velocity or the amount of moisture removed from the air supply causes an increase in packing height. Increasing the desiccant mass velocity decreases the packing height
Experimental characterization of a 400  Gbit/s orbital angular momentum multiplexed free-space optical link over 120 m
We experimentally demonstrate and characterize the
performance of a 400-Gbit/s orbital angular momentum
(OAM) multiplexed free-space optical link over 120-
meters on the roof of a building. Four OAM beams, each
carrying a 100-Gbit/s QPSK channel are multiplexed and
transmitted. We investigate the influence of channel
impairments on the received power, inter-modal
crosstalk among channels, and system power penalties.
Without laser tracking and compensation systems, the
measured received power and crosstalk among OAM
channels fluctuate by 4.5 dB and 5 dB, respectively, over
180 seconds. For a beam displacement of 2 mm that
corresponds to a pointing error less than 16.7 μrad, the
link bit-error-rates are below the forward error
correction threshold of 3.8×10-3 for all channels. Both
experimental and simulation results show that power
penalties increase rapidly when the displacement
increases
Human embryonic myosin heavy chain cDNA Interspecies sequence conservation of the myosin rod, chromosomal locus and isoform specific transcription of the gene
AbstractA 3.6 kilobase cDNA clone coding for the human embryonic myosin heavy chain has been isolated and characterized from an expression library prepared from human fetal skeletal muscle. The derived amino acid sequence for the entire rod part of myosin shows 97% sequence homology between human and rat and a striking interspecies sequence conservation among the charged amino acid residues. The single copy gene is localized to human chromosome 17 and its expression in fetal skeletal muscle is developmentally regulated. The sequence information permits the design of isoform-specific probes for studies on the structure of the gene and its role in normal and defective human myogenesis.Myosin heavy chain cDNA; Nucleotide sequence; Amino acid sequence; Myosin rod; Chromosomal mapping; Gene transcription; (Human embryo
Simultaneous Pre-and Post-Turbulence Compensation of Multiple Orbital-Angular-Momentum 100-Gbit/s Data Channels in a Bidirectional Link Using a Single Adaptive-Optics System
The simultaneous pre-and post-turbulence compensation of multiple orbital-angular-momentum (OAM) modes propagating through turbulent channel is experimentally demonstrated in a bidirectional free-space optical (FSO) link by using a single adaptive-optics system.United States. Defense Advanced Research Projects Agency. Information in a Photon (InPho) ProgramIntel Corporatio
Disruption of the Opal Stop Codon Attenuates Chikungunya Virus-Induced Arthritis and Pathology
ABSTRACT Chikungunya virus (CHIKV) is a mosquito-borne alphavirus responsible for several significant outbreaks of debilitating acute and chronic arthritis and arthralgia over the past decade. These include a recent outbreak in the Caribbean islands and the Americas that caused more than 1 million cases of viral arthralgia. Despite the major impact of CHIKV on global health, viral determinants that promote CHIKV-induced disease are incompletely understood. Most CHIKV strains contain a conserved opal stop codon at the end of the viral nsP3 gene. However, CHIKV strains that encode an arginine codon in place of the opal stop codon have been described, and deep-sequencing analysis of a CHIKV isolate from the Caribbean identified both arginine and opal variants within this strain. Therefore, we hypothesized that the introduction of the arginine mutation in place of the opal termination codon may influence CHIKV virulence. We tested this by introducing the arginine mutation into a well-characterized infectious clone of a CHIKV strain from Sri Lanka and designated this virus Opal524R. This mutation did not impair viral replication kinetics in vitro or in vivo . Despite this, the Opal524R virus induced significantly less swelling, inflammation, and damage within the feet and ankles of infected mice. Further, we observed delayed induction of proinflammatory cytokines and chemokines, as well as reduced CD4 + T cell and NK cell recruitment compared to those in the parental strain. Therefore, the opal termination codon plays an important role in CHIKV pathogenesis, independently of effects on viral replication. IMPORTANCE Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes significant outbreaks of viral arthralgia. Studies with CHIKV and other alphaviruses demonstrated that the opal termination codon within nsP3 is highly conserved. However, some strains of CHIKV and other alphaviruses contain mutations in the opal termination codon. These mutations alter the virulence of related alphaviruses in mammalian and mosquito hosts. Here, we report that a clinical isolate of a CHIKV strain from the recent outbreak in the Caribbean islands contains a mixture of viruses encoding either the opal termination codon or an arginine mutation. Mutating the opal stop codon to an arginine residue attenuates CHIKV-induced disease in a mouse model. Compared to infection with the opal-containing parental virus, infection with the arginine mutant causes limited swelling and inflammation, as well as dampened recruitment of immune mediators of pathology, including CD4 + T cells and NK cells. We propose that the opal termination codon plays an essential role in the induction of severe CHIKV disease
γδ T cells play a protective role in Chikungunya virus-induced disease
Chikungunya virus (CHIKV) is an alphavirus responsible for causing epidemic outbreaks of polyarthralgia in humans. Because CHIKV is initially introduced via the skin, where γδ T cells are prevalent, we evaluated the response of these cells to CHIKV infection. CHIKV infection led to a significant increase in γδ T cells in the infected foot and draining lymph node that was associated with the production of proinflammatory cytokines and chemokines in C57BL/6J mice. γδ T cell-/- mice demonstrated exacerbated CHIKV disease characterized by less weight gain and greater foot swelling than occurred in wild-type mice, as well as a transient increase in monocytes and altered cytokine/chemokine expression in the foot. Histologically, γδ T cell-/- mice had increased inflammation-mediated oxidative damage in the ipsilateral foot and ankle joint compared to wild-type mice which was independent of differences in CHIKV replication. These results suggest that γδ T cells play a protective role in limiting the CHIKV-induced inflammatory response and subsequent tissue and joint damage
Gamma-delta T cells play a protective role in chikungunya virus-induced disease.
Chikungunya virus (CHIKV) is an alphavirus responsible for causing epidemic outbreaks of polyarthralgia in humans. As CHIKV is initially introduced into the skin where γδ T cells are prevalent, we evaluated their response to CHIKV infection. CHIKV infection led to a significant increase in γδ T cells in the infected foot and draining lymph node associated with the production of pro-inflammatory cytokines and chemokines in C57BL/6J mice. γδ T cell-/- mice demonstrated exacerbated CHIKV disease characterized by less weight gain and greater foot swelling compared to wild-type mice as well as a transient increase in monocytes and altered cytokine/chemokine expression in the foot. Histologically, γδ T cell-/- mice had increased inflammation-mediated oxidative damage in the ipsilateral foot and ankle joint of versus wild-type mice which was independent of differences in CHIKV replication. These results suggest that γδ T cells play a protective role in limiting the CHIKV-induced inflammatory response and subsequent tissue and joint damage. Recent epidemics including the 2004-2007 outbreak and the spread of CHIKV to naïve populations in the Caribbean, Central and South America with resultant cases imported into the U.S highlighted the capacity of CHIKV to cause explosive epidemics where the virus can spread to millions of people and rapidly move into new areas. These studies identify γδ T cells as being important to both recruitment of key inflammatory cell populations and dampening the tissue injury due to oxidative stress. Given the importance of these cells in the early response to CHIKV, this information may inform the development of CHIKV vaccines and therapeutics
The First Hour of Extra-galactic Data of the Sloan Digital Sky Survey Spectroscopic Commissioning: The Coma Cluster
On 26 May 1999, one of the Sloan Digital Sky Survey (SDSS) fiber-fed
spectrographs saw astronomical first light. This was followed by the first
spectroscopic commissioning run during the dark period of June 1999. We present
here the first hour of extra-galactic spectroscopy taken during these early
commissioning stages: an observation of the Coma cluster of galaxies. Our data
samples the Southern part of this cluster, out to a radius of 1.5degrees and
thus fully covers the NGC 4839 group. We outline in this paper the main
characteristics of the SDSS spectroscopic systems and provide redshifts and
spectral classifications for 196 Coma galaxies, of which 45 redshifts are new.
For the 151 galaxies in common with the literature, we find excellent agreement
between our redshift determinations and the published values. As part of our
analysis, we have investigated four different spectral classification
algorithms: spectral line strengths, a principal component decomposition, a
wavelet analysis and the fitting of spectral synthesis models to the data. We
find that a significant fraction (25%) of our observed Coma galaxies show signs
of recent star-formation activity and that the velocity dispersion of these
active galaxies (emission-line and post-starburst galaxies) is 30% larger than
the absorption-line galaxies. We also find no active galaxies within the
central (projected) 200 h-1 Kpc of the cluster. The spatial distribution of our
Coma active galaxies is consistent with that found at higher redshift for the
CNOC1 cluster survey. Beyond the core region, the fraction of bright active
galaxies appears to rise slowly out to the virial radius and are randomly
distributed within the cluster with no apparent correlation with the potential
merger of the NGC 4839 group. [ABRIDGED]Comment: Accepted in AJ, 65 pages, 20 figures, 5 table
The Sloan Digital Sky Survey Quasar Catalog I. Early Data Release
We present the first edition of the Sloan Digital Sky Survey (SDSS) Quasar
Catalog. The catalog consists of the 3814 objects (3000 discovered by the SDSS)
in the initial SDSS public data release that have at least one emission line
with a full width at half maximum larger than 1000 km/s, luminosities brighter
than M_i^* = -23, and highly reliable redshifts. The area covered by the
catalog is 494 square degrees; the majority of the objects were found in SDSS
commissioning data using a multicolor selection technique. The quasar redshifts
range from 0.15 to 5.03. For each object the catalog presents positions
accurate to better than 0.2" rms per coordinate, five band (ugriz) CCD-based
photometry with typical accuracy of 0.05 mag, radio and X-ray emission
properties, and information on the morphology and selection method. Calibrated
spectra of all objects in the catalog, covering the wavelength region 3800 to
9200 Angstroms at a spectral resolution of 1800-2100, are also available. Since
the quasars were selected during the commissioning period, a time when the
quasar selection algorithm was undergoing frequent revisions, the sample is not
homogeneous and is not intended for statistical analysis.Comment: 27 pages, 4 figures, 4 tables, accepted by A
Galaxy Clustering in Early SDSS Redshift Data
We present the first measurements of clustering in the Sloan Digital Sky
Survey (SDSS) galaxy redshift survey. Our sample consists of 29,300 galaxies
with redshifts 5,700 km/s < cz < 39,000 km/s, distributed in several long but
narrow (2.5-5 degree) segments, covering 690 square degrees. For the full,
flux-limited sample, the redshift-space correlation length is approximately 8
Mpc/h. The two-dimensional correlation function \xi(r_p,\pi) shows clear
signatures of both the small-scale, ``fingers-of-God'' distortion caused by
velocity dispersions in collapsed objects and the large-scale compression
caused by coherent flows, though the latter cannot be measured with high
precision in the present sample. The inferred real-space correlation function
is well described by a power law, \xi(r)=(r/6.1+/-0.2 Mpc/h)^{-1.75+/-0.03},
for 0.1 Mpc/h < r < 16 Mpc/h. The galaxy pairwise velocity dispersion is
\sigma_{12} ~ 600+/-100 km/s for projected separations 0.15 Mpc/h < r_p < 5
Mpc/h. When we divide the sample by color, the red galaxies exhibit a stronger
and steeper real-space correlation function and a higher pairwise velocity
dispersion than do the blue galaxies. The relative behavior of subsamples
defined by high/low profile concentration or high/low surface brightness is
qualitatively similar to that of the red/blue subsamples. Our most striking
result is a clear measurement of scale-independent luminosity bias at r < 10
Mpc/h: subsamples with absolute magnitude ranges centered on M_*-1.5, M_*, and
M_*+1.5 have real-space correlation functions that are parallel power laws of
slope ~ -1.8 with correlation lengths of approximately 7.4 Mpc/h, 6.3 Mpc/h,
and 4.7 Mpc/h, respectively.Comment: 51 pages, 18 figures. Replaced to match accepted ApJ versio
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