907 research outputs found
THE MICHIGAN STUDY-DISCUSSION PROGRAM, "DEVELOPING HUMAN RESOURCES IN MICHIGAN"
Labor and Human Capital,
Drum Transcription via Classification of Bar-level Rhythmic Patterns
acceptedMatthias Mauch is supported by a Royal Academy of Engineering
Research Fellowshi
The Stripe 82 1-2 GHz Very Large Array Snapshot Survey: Multiwavelength Counterparts
We have combined spectrosopic and photometric data from the Sloan Digital Sky
Survey (SDSS) with GHz radio observations, conducted as part of the
Stripe 82 GHz Snapshot Survey using the Karl G. Jansky Very Large Array
(VLA), which covers sq degrees, to a flux limit of 88 Jy rms.
Cross-matching the radio source components with optical data via
visual inspection results in a final sample of cross-matched objects,
of which have spectroscopic redshifts and objects have
photometric redshifts. Three previously undiscovered Giant Radio Galaxies
(GRGs) were found during the cross-matching process, which would have been
missed using automated techniques. For the objects with spectroscopy we
separate radio-loud Active Galactic Nuclei (AGN) and star-forming galaxies
(SFGs) using three diagnostics and then further divide our radio-loud AGN into
the HERG and LERG populations. A control matched sample of HERGs and LERGs,
matched on stellar mass, redshift and radio luminosity, reveals that the host
galaxies of LERGs are redder and more concentrated than HERGs. By combining
with near-infrared data, we demonstrate that LERGs also follow a tight
relationship. These results imply the LERG population are hosted by population
of massive, passively evolving early-type galaxies. We go on to show that
HERGs, LERGs, QSOs and star-forming galaxies in our sample all reside in
different regions of a WISE colour-colour diagram. This cross-matched sample
bridges the gap between previous `wide but shallow' and `deep but narrow'
samples and will be useful for a number of future investigations.Comment: 17 pages, 19 figures. Resubmitted to MNRAS after the initial comment
Subcellular immunocytochemical analysis detects the highest concentrations of glutathione in mitochondria and not in plastids
The tripeptide glutathione is a major antioxidant and redox buffer with multiple roles in plant metabolism. Glutathione biosynthesis is restricted to the cytosol and the plastids and the product is distributed to the various organelles by unknown mechanisms. In the present study immunogold cytochemistry based on anti-glutathione antisera and transmission electron microscopy was used to determine the relative concentration of glutathione in different organelles of Arabidopsis thaliana leaf and root cells. Glutathione-specific labelling was detected in all cellular compartments except the apoplast and the vacuole. The highest glutathione content was surprisingly not found in plastids, which have been described before as a major site of glutathione accumulation, but in mitochondria which lack the capacity for glutathione biosynthesis. Mitochondria of both leaf and root cells contained 7-fold and 4-fold, respectively, higher glutathione levels than plastids while the density of glutathione labelling in the cytosol, nuclei, and peroxisomes was intermediate. The accuracy of the glutathione labelling is supported by two observations. First, pre-adsorption of the anti-glutathione antisera with glutathione reduced the density of the gold particles in all organelles to background levels. Second, the overall glutathione-labelling density was reduced by about 90% in leaves of the glutathione-deficient Arabidopsis mutant pad2-1 and increased in transgenic plants with enhanced glutathione accumulation. Hence, there was a strong correlation between immunocytochemical and biochemical data of glutathione accumulation. Interestingly, the glutathione labelling of mitochondria in pad2-1 remained very similar to wild-type plants thus suggesting that the high mitochondrial glutathione content is maintained in a situation of permanent glutathione-deficiency at the expense of other glutathione pools. High and constant levels of glutathione in mitochondria appear to be particularly important in cell survival strategies and it is predicted that mitochondria must have highly competitive mitochondrial glutathione uptake systems. The present results underline the suggestion that subcellular glutathione concentrations are not controlled by a global mechanism but are controlled on an individual basis and it is therefore not possible to conclude from global biochemical glutathione analysis on the status of the various organellar pool
Análise técnico-econômica de dois sistemas de produção de cebola: orgânico e convencional - estudo de caso.
bitstream/item/31481/1/comunicado-210.pd
Radio sources with ultra-high polarization
A sample of 129 unresolved radio sources with ultrahigh linear polarization
(>30 per cent) has been selected from the NRAO VLA Sky Survey. Such high
average linear polarization is unusual in extragalactic sources. Higher
resolution Australia Telescope Compact Array and Very Large Array observations
confirm the high average polarization but find that most of these sources are
extended. The Sloan Digital Sky Survey spectroscopy, where available, shows
that the optical counterparts are elliptical galaxies with no detectable
emission lines. The optical spectra, radio luminosity, linear size and spectral
index of these sources are typical of radio-loud active galactic nuclei. Galaxy
counts within a 1 Mpc radius of the radio sources show that these highly
polarized sources are in environments similar to their low polarization (<2 per
cent) counterparts. Similarly, the line-of-sight environments of the ultrahigh
polarization sources are on average indistinguishable from those of the
low-polarization sources. We conclude that the extraordinarily high average
polarization must be due to intrinsic properties of the sources, such as an
extremely ordered source magnetic field, low internal thermal plasma density or
a preferential orientation of the source magnetic field perpendicular to the
line of sight.Comment: 23 pages, 15 figures, 6 tables, accepted for publication in MNRAS;
v2: some typos correcte
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Coastal ocean variability inferred from high resolution models : two case studies
In this thesis, high resolution ocean models are used to evaluate and forecast coastal ocean variability in two different applications. In the first study, the 2-km resolution ocean circulation model for the Eastern Bering Sea is utilized to understand whether slope-interior exchange along the path of the Aleutian North Slope Current (ANSC) helps maintain the subsurface temperature maximum on the isopycnal surface 26.8 kg m⁻³, approximately 300-400 m deep. The simulation period is June-October of 2009. At the abovementioned isopycnal surface, the model shows the warmer pattern extending westward along the southern slope of the Aleutian Islands and then eastward along the northern slope as the season progresses. The direct exchange from the south to the north through Amukta Pass on this isopycnal surface is very limited. The model does not exhibit vigorous eddy shedding along the ANSC. However, there are several topographic features where the warm slope current separates into the basin, particularly at 178˚ W (just east of Amchitka Pass) and 174˚ W (Atka Island). Currents on the 26.8 kg m⁻³ isopycnal surface are too slow to account for the warming pattern along the ANSC reaching the Bering Canyon and the Bering Slope Current. The warming can be explained as a combination of faster advection of warmer waters above and downward vertical turbulent transport due to intensive tides. This hypothesis is confirmed by the heat equation term balance analysis and two-dimensional Lagrangian particle tracking on the 26.8 kg m⁻³ surface and a shallower, 26.4 kg m⁻³ surface. In the second study, a team of four graduate students, including two ocean modelers, a cartographer, and a social scientist, work together as part of the National Science Foundation Research Trainee (NRT) program to develop new products based on ocean forecasts, quantify their uncertainty and communicate this knowledge to commercial fishermen. A 2-km resolution ocean prediction system for the Oregon and Washington coasts produces three-day forecasts of surface velocity, temperature, and salinity. Based on the social scientist’s communications with the commercial fishermen on their perceptions of risk and uncertainty, uncertainty in the surface current forecast is quantified by calculating the root mean square error of the forecast with high frequency radar observations for each forecast horizon. This calculation reveals that the model performs better in the northern portion of the domain where high frequency radar observations are available, with a noticeable source of error being near the Columbia River Estuary. Additionally, the depth of the thermocline is calculated with two different methods: as a depth at which the temperature is 2˚F less than the surface temperature (a definition provided by the commercial fishermen) and as a depth of the maximum buoyancy frequency squared. Overall, the two parts of our thesis study complement each other showing that coastal ocean models can be used both for basic oceanographic research and for operational prediction.Keywords: Ocean Modeling, Physical Oceanograph
Evidence of a link between the evolution of clusters and their AGN fraction
‘The definitive version is available at www3.interscience.wiley.com .' Copyright Blackwell Publishing / Royal Astronomical Society. DOI: 10.1111/j.1365-2966.2009.14513.xPeer reviewe
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Improving music genre classification using automatically induced harmony rules
We present a new genre classification framework using both low-level signal-based features and high-level harmony features. A state-of-the-art statistical genre classifier based on timbral features is extended using a first-order random forest containing for each genre rules derived from harmony or chord sequences. This random forest has been automatically induced, using the first-order logic induction algorithm TILDE, from a dataset, in which for each chord the degree and chord category are identified, and covering classical, jazz and pop genre classes. The audio descriptor-based genre classifier contains 206 features, covering spectral, temporal, energy, and pitch characteristics of the audio signal. The fusion of the harmony-based classifier with the extracted feature vectors is tested on three-genre subsets of the GTZAN and ISMIR04 datasets, which contain 300 and 448 recordings, respectively. Machine learning classifiers were tested using 5 × 5-fold cross-validation and feature selection. Results indicate that the proposed harmony-based rules combined with the timbral descriptor-based genre classification system lead to improved genre classification rates
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