2,147 research outputs found
Power Supply for Driving High Power LEDs with Wireless Control
This project is the design of a power supply for driving high power light emitting diodes (LEDs) with wireless control. The project is divided into two sections, the power supply for driving the LED lights, and the wireless control and fan power supply
α-Synuclein Aggregation Inhibitory Prunolides and a Dibrominated β-Carboline Sulfamate from the Ascidian Synoicum prunum
Seven new polyaromatic bis-spiroketal-containing butenolides, the prunolides D–I (4–9) and cis-prunolide C (10), a new dibrominated β-carboline sulfamate named pityriacitrin C (11), alongside the known prunolides A–C (1–3) were isolated from the Australian colonial ascidian Synoicum prunum. The prunolides D–G (4–7) represent the first asymmetrically brominated prunolides, while cis-prunolide C (10) is the first reported with a cis-configuration about the prunolide’s bis-spiroketal core. The prunolides displayed binding activities with the Parkinson’s disease-implicated amyloid protein α-synuclein in a mass spectrometry binding assay, while the prunolides (1–5 and 10) were found to significantly inhibit the aggregation (>89.0%) of α-synuclein in a ThT amyloid dye assay. The prunolides A–C (1–3) were also tested for inhibition of pSyn aggregate formation in a primary embryonic mouse midbrain dopamine neuron model with prunolide B (2) displaying statistically significant inhibitory activity at 0.5 μM. The antiplasmodial and antibacterial activities of the isolates were also examined with prunolide C (3) displaying only weak activity against the 3D7 parasite strain of Plasmodium falciparum. Our findings reported herein suggest that the prunolides could provide a novel scaffold for the exploration of future therapeutics aimed at inhibiting amyloid protein aggregation and the treatment of numerous neurodegenerative diseases.Peer reviewe
Succinylated Octopamine Ascarosides and a New Pathway of Biogenic Amine Metabolism in Caenorhabditis elegans
The ascarosides, small-molecule signals derived from combinatorial
assembly of primary metabolism-derived building
blocks, play a central role in Caenorhabditis elegans biology and
regulate many aspects of development and behavior in this
model organism as well as in other nematodes. Using HPLCMS/
MS-based targeted metabolomics, we identified novel ascarosides
incorporating a side chain derived from succinylation of
the neurotransmitter octopamine. These compounds, named
osas#2, osas#9, and osas#10, are produced predominantly by L1
larvae, where they serve as part of a dispersal signal, whereas
these ascarosides are largely absent from the metabolomes of
other life stages. Investigating the biogenesis of these octopamine-
derived ascarosides, we found that succinylation represents
a previously unrecognized pathway of biogenic amine
metabolism. At physiological concentrations, the neurotransmitters
serotonin, dopamine, and octopamine are converted to a
large extent into the corresponding succinates, in addition to
the previously described acetates. Chemically, bimodal deactivation
of biogenic amines via acetylation and succinylation parallels
posttranslational modification of proteins via acetylation
and succinylation of L-lysine. Our results reveal a small-molecule
connection between neurotransmitter signaling and
interorganismal regulation of behavior and suggest that ascaroside
biosynthesis is based in part on co-option of degradative
biochemical pathways
Higher Order Moments of the Angular Distribution of Galaxies from Early SDSS Data
We present initial results for counts in cells statistics of the angular
distribution of galaxies in early data from the Sloan Digital Sky Survey
(SDSS). We analyze a rectangular stripe wide, covering
approximately 160 sq. degrees, containing over galaxies in the apparent
magnitude range , with areas of bad seeing, contamination
from bright stars, ghosts, and high galactic extinction masked out. This survey
region, which forms part of the SDSS Early Data Release, is the same as that
for which two-point angular clustering statistics have recently been computed.
The third and fourth moments of the cell counts, (skewness) and
(kurtosis), constitute the most accurate measurements to date of these
quantities (for ) over angular scales .
They display the approximate hierarchical scaling expected from non-linear
structure formation models and are in reasonable agreement with the predictions
of -dominated cold dark matter models with galaxy biasing that
suppresses higher order correlations at small scales. The results are in
general consistent with previous measurements in the APM, EDSGC, and Deeprange
surveys. These results suggest that the SDSS imaging data are free of
systematics to a high degree and will therefore enable determination of the
skewness and kurtosis to 1% and less then 10%, as predicted by Colombi,
Szapudi, & Szalay (1998).Comment: 24 pages, submitted to Ap
KL Estimation of the Power Spectrum Parameters from the Angular Distribution of Galaxies in Early SDSS Data
We present measurements of parameters of the 3-dimensional power spectrum of
galaxy clustering from 222 square degrees of early imaging data in the Sloan
Digital Sky Survey. The projected galaxy distribution on the sky is expanded
over a set of Karhunen-Loeve eigenfunctions, which optimize the signal-to-noise
ratio in our analysis. A maximum likelihood analysis is used to estimate
parameters that set the shape and amplitude of the 3-dimensional power
spectrum. Our best estimates are Gamma=0.188 +/- 0.04 and sigma_8L = 0.915 +/-
0.06 (statistical errors only), for a flat Universe with a cosmological
constant. We demonstrate that our measurements contain signal from scales at or
beyond the peak of the 3D power spectrum. We discuss how the results scale with
systematic uncertainties, like the radial selection function. We find that the
central values satisfy the analytically estimated scaling relation. We have
also explored the effects of evolutionary corrections, various truncations of
the KL basis, seeing, sample size and limiting magnitude. We find that the
impact of most of these uncertainties stay within the 2-sigma uncertainties of
our fiducial result.Comment: Fig 1 postscript problem correcte
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 shape of the SDSS DR5 galaxy power spectrum
We present a Fourier analysis of the clustering of galaxies in the combined
Main galaxy and Luminous Red Galaxy (LRG) Sloan Digital Sky Survey (SDSS) Data
Release 5 (DR5) sample. The aim of our analysis is to consider how well we can
measure the cosmological matter density using the signature of the horizon at
matter-radiation equality embedded in the large-scale power spectrum. The new
data constrains the power spectrum on scales 100--600h^-1Mpc with significantly
higher precision than previous analyses of just the SDSS Main galaxies, due to
our larger sample and the inclusion of the LRGs. This improvement means that we
can now reveal a discrepancy between the shape of the measured power and linear
CDM models on scales 0.01<k<0.15hMpc^-1, with linear model fits favouring a
lower matter density (Omega_m=0.22+/-0.04) on scales 0.01<k<0.06hMpc^-1 and a
higher matter density (Omega_m=0.32+/-0.01) when smaller scales are included,
assuming a flat LCDM model with h=0.73 and n_s=0.96. This discrepancy could be
explained by scale-dependent bias and, by analysing subsamples of galaxies, we
find that the ratio of small-scale to large-scale power increases with galaxy
luminosity, so all of the SDSS galaxies cannot trace the same power spectrum
shape over 0.01<k<0.2hMpc^-1. However, the data are insufficient to clearly
show a luminosity-dependent change in the largest scale at which a significant
increase in clustering is observed, although they do not rule out such an
effect. Significant scale-dependent galaxy bias on large-scales, which changes
with the r-band luminosity of the galaxies, could potentially explain
differences in our Omega_m estimates and differences previously observed
between 2dFGRS and SDSS power spectra and the resulting parameter constraints.Comment: 21 pages, 19 figures, minor corrections to match version accepted by
Ap
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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