12,157 research outputs found
Remote sensing of effects of land use practices on water quality
An intensive study was conducted to determine the utility of manual densitometry and color additive viewing of aircraft and LANDSAT transparencies for monitoring land use and land use change. The relationship between land use and selected water quality parameters was also evaluated. Six watersheds located in the Cumberland Plateau region of eastern Kentucky comprised the study area for the project. Land uses present within the study area were reclaimed surface mining and forestry. Fertilization of one of the forested watersheds also occurred during the study period
Usability Testing and Instruction Librarians: A Perfect Pair.
This study examines how librarians are experiencing usability testing and how their observations are influencing library instruction. A survey of instruction librarians illustrates how usability testing and library instruction are connected. Survey results prove instruction librarians are involved in usability testing. Furthermore, their participation in usability studies has led instruction librarians to alter their instructional methods. An overwhelming majority changed one or more instructional tools as a result of usability testing, and many reported creating new instructional resources. The authors add their own insights as both instruction librarians and participants in usability testing
Deep Chronnectome Learning via Full Bidirectional Long Short-Term Memory Networks for MCI Diagnosis
Brain functional connectivity (FC) extracted from resting-state fMRI
(RS-fMRI) has become a popular approach for disease diagnosis, where
discriminating subjects with mild cognitive impairment (MCI) from normal
controls (NC) is still one of the most challenging problems. Dynamic functional
connectivity (dFC), consisting of time-varying spatiotemporal dynamics, may
characterize "chronnectome" diagnostic information for improving MCI
classification. However, most of the current dFC studies are based on detecting
discrete major brain status via spatial clustering, which ignores rich
spatiotemporal dynamics contained in such chronnectome. We propose Deep
Chronnectome Learning for exhaustively mining the comprehensive information,
especially the hidden higher-level features, i.e., the dFC time series that may
add critical diagnostic power for MCI classification. To this end, we devise a
new Fully-connected Bidirectional Long Short-Term Memory Network (Full-BiLSTM)
to effectively learn the periodic brain status changes using both past and
future information for each brief time segment and then fuse them to form the
final output. We have applied our method to a rigorously built large-scale
multi-site database (i.e., with 164 data from NCs and 330 from MCIs, which can
be further augmented by 25 folds). Our method outperforms other
state-of-the-art approaches with an accuracy of 73.6% under solid
cross-validations. We also made extensive comparisons among multiple variants
of LSTM models. The results suggest high feasibility of our method with
promising value also for other brain disorder diagnoses.Comment: The paper has been accepted by MICCAI201
The Peak Brightness and Spatial Distribution of AGB Stars Near the Nucleus of M32
The bright stellar content near the center of the Local Group elliptical
galaxy M32 is investigated with 0.12 arcsec FWHM H and K images obtained with
the Gemini Mauna Kea telescope. Stars with K = 15.5, which are likely evolving
near the tip of the asymptotic giant branch (AGB), are resolved to within 2
arcsec of the nucleus, and it is concluded that the peak stellar brightness
near the center of M32 is similar to that in the outer regions of the galaxy.
Moreover, the projected density of bright AGB stars follows the visible light
profile to within 2 arcsec of the nucleus, indicating that the brightest stars
are well mixed throughout the galaxy. Thus, there is no evidence for an age
gradient, and the radial variations in spectroscopic indices and ultraviolet
colors that have been detected previously must be due to metallicity and/or
some other parameter. We suggest that either the bright AGB stars formed as
part of a highly uniform and coherent galaxy-wide episode of star formation, or
they originated in a separate system that merged with M32.Comment: 9 pages of text, 3 figures. ApJ (Letters) in pres
The Stellar Halos of Massive Elliptical Galaxies II: Detailed Abundance Ratios at Large Radius
We study the radial dependence in stellar populations of 33 nearby early-type
galaxies with central stellar velocity dispersions sigma* > 150 km/s. We
measure stellar population properties in composite spectra, and use ratios of
these composites to highlight the largest spectral changes as a function of
radius. Based on stellar population modeling, the typical star at 2 R_e is old
(~10 Gyr), relatively metal poor ([Fe/H] -0.5), and alpha-enhanced
([Mg/Fe]~0.3). The stars were made rapidly at z~1.5-2 in shallow potential
wells. Declining radial gradients in [C/Fe], which follow [Fe/H], also arise
from rapid star formation timescales due to declining carbon yields from
low-metallicity massive stars. In contrast, [N/Fe] remains high at large
radius. Stars at large radius have different abundance ratio patterns from
stars in the center of any present-day galaxy, but are similar to Milky Way
thick disk stars. Our observations are thus consistent with a picture in which
the stellar outskirts are built up through minor mergers with disky galaxies
whose star formation is truncated early (z~1.5-2).Comment: ApJ in press, 12 pages, 6 figure
Does increasing methylphenidate dose aid symptom control in ADHD?
Most children with attention deficit/ hyperactivity disorder (ADHD) who are started on methylphenidate will respond favorably to a dose increase if the initial dose does not sufficiently reduce symptoms. Once titrated to an effective maintenance dose, frequent follow-up is necessary to monitor for side effects and recurring symptoms. The dose of methylphenidate can then be increased further for better symptom control, which may be warranted in most cases. In some children, methylphenidate may not achieve response even at high doses or may cause intolerable side effects. For these children, start a different stimulant medication (strength of recommendation: B, based on extrapolation of 1 randomized controlled trial)
A protocol to encourage accelerometer wear in children and young people
Background: Improving compliance to physical activity monitoring is critical for obtaining valid, comparable data free from inconsistencies that occur during data reduction. The first aim of this study was to investigate children (8-11 years) and young people’s (12-15 years) views on strategies to promote habitual wear of hip (ActiGraph) and wrist-worn (GENEActiv) accelerometers. The second aim was to subsequently develop a protocol to reduce participant and researcher burden and maximise accelerometer wear time data. Methods: An interpretivist methodology was used with semi-structured, mixed-gender focus groups in 7 elementary (n=10; 47 children) and 5 high schools (n =10; 49 young people). Focus groups were transcribed verbatim and outcomes from deductive and inductive analysis were represented via pen profiles. Results: Deductive content analysis revealed four general dimensions: 1) participant driven compliance strategies; 2) reasons for non-compliance to wear time; 3) strategies to improve accelerometer care; 4) reasons for non-compliance to study conditions. Children perceived popular wear time compliance strategies to be: 1) sticky note reminders; 2) mobile phone reminders; 3) social conformity, whereas young people’s perceptions were: 1) social conformity; 2) mobile phone reminders; 3) monetary compensation. Conclusions: Where possible, compliance strategies should accommodate the varying preferences of children and young people. It is recommended that future accelerometry based research adopts a formative phase. In the absence of a formative research phase, future research should consider the use of this informed protocol to improve compliance to physical activity monitoring in children and young people
Sub-picosecond compression by velocity bunching in a photo-injector
We present an experimental evidence of a bunch compression scheme that uses a
traveling wave accelerating structure as a compressor. The bunch length issued
from a laser-driven radio-frequency electron source was compressed by a factor
>3 using an S-band traveling wave structure located immediately downstream from
the electron source. Experimental data are found to be in good agreement with
particle tracking simulations.Comment: 19 pages, 9 figures, submitted to Phys. Rev. Spec. Topics A&
The Stellar Halos of Massive Elliptical Galaxies
We use the Mitchell Spectrograph (formerly VIRUS-P) on the McDonald
Observatory 2.7m Harlan J. Smith Telescope to search for the chemical
signatures of massive elliptical galaxy assembly. The Mitchell Spectrograph is
an integral-field spectrograph with a uniquely wide field of view (107x107 sq
arcsec), allowing us to achieve remarkably high signal-to-noise ratios of
~20-70 per pixel in radial bins of 2-2.5 times the effective radii of the eight
galaxies in our sample. Focusing on a sample of massive elliptical galaxies
with stellar velocity dispersions sigma* > 150 km/s, we study the radial
dependence in the equivalent widths (EWs) of key metal absorption lines. By
twice the effective radius, the Mgb EWs have dropped by ~50%, and only a weak
correlation between sigma* and Mgb EW remains. The Mgb EWs at large radii are
comparable to those seen in the centers of elliptical galaxies that are
approximately an order of magnitude less massive. We find that the well-known
metallicity gradients often observed within an effective radius continue
smoothly to 2.5R_e, while the abundance ratio gradients remain flat. Much like
the halo of the Milky Way, the stellar halos of our galaxies have low
metallicities and high alpha-abundance ratios, as expected for very old stars
formed in small stellar systems. Our observations support a picture in which
the outer parts of massive elliptical galaxies are built by the accretion of
much smaller systems whose star formation history was truncated at early times.Comment: To appear in ApJ, 15 pages, 9 figure
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