6,080 research outputs found
A case for inherent geometric and geodetic accuracy in remotely sensed VNIR and SWIR imaging products
Significant aberrations can occur in acquired images which, unless compensated on board the spacecraft, can seriously impair throughput and timeliness for typical Earth observation missions. Conceptual compensations options are advanced to enable acquisition of images with inherent geometric and geodetic accuracy. Research needs are identified which, when implemented, can provide inherently accurate images. Agressive pursuit of these research needs is recommended
A three-dimensional turbulent boundary layer undergoing transverse strain and streamwise pressure gradient
Results from an experimental investigation designed to provide data on both mean and turbulence quantities in the axisymmetric, swirling boundary layer (with and without pressure gradient) flowing over a stationary cylinder downstreams of a spinning cylindrical section are presented. The pressure gradient was introduced into the flow field by a 25.4 mm-high, forward-facing, circular step mounted on the stationary cylinder, the step height being nearly equal to the thickness of the approaching boundary layer. All the measurements were made at a nominal upstream reference Reynolds number of 2.4 x 10 to the 6th power/m (corresponding to an upstream reference velocity of 36 to 37 m/sec) with the rotation of the spinner set to make its peripheral speed equal the reference velocity. The data reported included measurements of surface pressure and the mean surface shear-stress vector taken with a miniature, directional, surface-fence gage. These measurements were supplemented by oil-flow visualization studies of the stationary cylinder. The data indicates that the streamwise pressure gradient controls the development of the streamwise component of wall shear, but leaves the peripheral component of wall shear practically unaffected
Group study of an 'undercover' test for visuospatial neglect: Invisible cancellation can reveal more neglect than standard cancellation
Visual neglect is a relatively common deficit after brain damage, particularly strokes. Cancellation tests provide standard clinical measures of neglect severity and deficits in daily life. A recent single-case study introduced a new variation on standard cancellation. Instead of making a visible mark on each target found, the patient made invisible marks (recorded with carbon paper underneath, for later scoring). Such invisible cancellation was found to reveal more neglect than cancellation with visible marks. Here we test the generality of this. Twenty three successive cases with suspected neglect each performed cancellation with visible or invisible marks. Neglect of contralesional targets was more pronounced with invisible marks. Indeed, about half of the patients only showed neglect in this version. For cases showing more neglect with invisible marks, stronger neglect of contralesional targets correlated with more revisits to ipsilesional targets for making additional invisible marks upon them. These results indicate that cancellation with invisible marks can reveal more neglect than standard cancellation with visible marks, while still providing a practical bedside test. Our observations may be consistent with recent proposals that demands on spatial working memory (required to keep track of previously found items only when marked invisibly) can exacerbate spatial neglect
The Special Verdict—Theory and Practice
At the 1949 Conference of Federal Judges of the Ninth Circuit I discussed the special verdict, and my address was published in the Washington Law Review. My treatment of the subject necessarily was largely theoretical as I had made very little use of the special verdict practice up to that time. Drawing upon abundant published material,I assembled and summarized the common criticisms of the general verdict and the claimed advantages of the special verdict, and expressed the conclusion that the latter, as prescribed in Rule 49 of the Federal Civil Rules, was entitled to much more extensive use. Having sold myself on that proposition, it was inevitable that I should try it out in practice. I shall now endeavor to give the bench and bar a candid account of the results of my experiment. Before doing so, however, I think it would be helpful to discuss briefly the defects of the general verdict which it is so often said the special verdict should remedy or at least minimize
Two-phase galaxy evolution: the cosmic star formation histories of spheroids and discs
From two very simple axioms: (1) that active galactic nucleus activity traces spheroid formation, and (2) that the cosmic star formation history is dominated by spheroid formation at high redshift, we derive simple expressions for the star formation histories of spheroids and discs, and their implied metal enrichment histories.
Adopting a Baldry–Glazebrook initial mass function we use these relations and apply PEGASE.2 to predict the z = 0 cosmic spectral energy distributions (CSEDs) of spheroids and discs. The model predictions compare favourably to the dust-corrected CSED recently reported by the Galaxy And Mass Assembly team from the far-ultraviolet through to the K band. The model also provides a reasonable fit to the total stellar mass contained within spheroid and disc structures as recently reported by the Millennium Galaxy Catalogue team. Three interesting inferences can be made following our axioms: (1) there is a transition redshift at z ≈ 1.7 at which point the Universe switches from what we refer to as ‘hot mode evolution’ (i.e. spheroid formation/growth via mergers and/or collapse) to what we term ‘cold mode evolution’ (i.e. disc formation/growth via gas infall and minor mergers); (2) there is little or no need for any pre-enrichment prior to the main phase of star formation; (3) in the present Universe mass loss is fairly evenly balanced with star formation holding the integrated stellar mass density close to a constant value.
The model provides a simple prediction of the energy output from spheroid and disc projenitors, the build-up of spheroid and disc mass and the mean metallicity enrichment of the Universe
Audiovisual temporal correspondence modulates human multisensory superior temporal sulcus plus primary sensory cortices
The brain should integrate related but not unrelated information from different senses. Temporal patterning of inputs to different modalities may provide critical information about whether those inputs are related or not. We studied effects of temporal correspondence between auditory and visual streams on human brain activity with functional magnetic resonance imaging ( fMRI). Streams of visual flashes with irregularly jittered, arrhythmic timing could appear on right or left, with or without a stream of auditory tones that coincided perfectly when present ( highly unlikely by chance), were noncoincident with vision ( different erratic, arrhythmic pattern with same temporal statistics), or an auditory stream appeared alone. fMRI revealed blood oxygenation level-dependent ( BOLD) increases in multisensory superior temporal sulcus (mSTS), contralateral to a visual stream when coincident with an auditory stream, and BOLD decreases for noncoincidence relative to unisensory baselines. Contralateral primary visual cortex and auditory cortex were also affected by audiovisual temporal correspondence or noncorrespondence, as confirmed in individuals. Connectivity analyses indicated enhanced influence from mSTS on primary sensory areas, rather than vice versa, during audiovisual correspondence. Temporal correspondence between auditory and visual streams affects a network of both multisensory ( mSTS) and sensory-specific areas in humans, including even primary visual and auditory cortex, with stronger responses for corresponding and thus related audiovisual inputs
Inclination-Independent Galaxy Classification
We present a new method to classify galaxies from large surveys like the
Sloan Digital Sky Survey using inclination-corrected concentration,
inclination-corrected location on the color-magnitude diagram, and apparent
axis ratio. Explicitly accounting for inclination tightens the distribution of
each of these parameters and enables simple boundaries to be drawn that
delineate three different galaxy populations: Early-type galaxies, which are
red, highly concentrated, and round; Late-type galaxies, which are blue, have
low concentrations, and are disk dominated; and Intermediate-type galaxies,
which are red, have intermediate concentrations, and have disks. We have
validated our method by comparing to visual classifications of high-quality
imaging data from the Millennium Galaxy Catalogue. The inclination correction
is crucial to unveiling the previously unrecognized Intermediate class.
Intermediate-type galaxies, roughly corresponding to lenticulars and early
spirals, lie on the red sequence. The red sequence is therefore composed of two
distinct morphological types, suggesting that there are two distinct mechanisms
for transiting to the red sequence. We propose that Intermediate-type galaxies
are those that have lost their cold gas via strangulation, while Early-type
galaxies are those that have experienced a major merger that either consumed
their cold gas, or whose merger progenitors were already devoid of cold gas
(the ``dry merger'' scenario).Comment: Accepted for publication in ApJ. 7 pages in emulateap
Juveniles’ Knowledge of the Court Process: Results from Instruction from an Electronic Source
Our study first determined what juveniles know about the juvenile court process. Second, it evaluated a DVD designed to be a systematic and simple way to improve this knowledge. A pre- and post-test design was used with two pilot samples and two samples from the population of interest. A sample from a juvenile detention center (n = 118) was the focus of this study. Initial knowledge of the court process was quite low for the detention sample (pretest M = 64.0%, SD = 14.2%). All samples experienced a significant improvement of knowledge after watching the DVD. Youth in the detention sample had a mean improvement from pretest to posttest of 6.4% (SD = 11.9%), with mean scores at posttest being 70.3% (SD = 17.4%). Respondents varied in their performance on different question topics, scoring the lowest on questions related to what happens at juvenile court hearings. The social and demographic variables of age, race, gender, grades in school, number of previous arrests, and the number of times the respondent had been to court were evaluated through regression analysis. Age and race were found to be significantly related to pretest scores, and race was significantly related to improvement scores
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