1,305 research outputs found
Statistical classification techniques for engineering and climatic data samples
Fisher's sample linear discriminant function is modified through an appropriate alteration of the common sample variance-covariance matrix. The alteration consists of adding nonnegative values to the eigenvalues of the sample variance covariance matrix. The desired results of this modification is to increase the number of correct classifications by the new linear discriminant function over Fisher's function. This study is limited to the two-group discriminant problem
Material Properties Measurements for Selected Materials
Hugoniot equation of state measurements were made on Coconino sandstone, Vacaville basalt, Kaibab limestone, Mono Crater, pumice and Zelux (a polycarbonate resin) for pressures to 2 Mb. A single data point was obtained for fused quartz at 1.6 Mb. In addition to the hugoniot studies, the uniaxial compressive stress behavior of Vacaville basalt and Zelux was investigated at strain rates from about 10(exp -5)/sec to 10(exp 3)/second. The data presented include the stress - strain relations as a function of strain rate for these two materials
Calibrating AIS images using the surface as a reference
A method of evaluating the initial assumptions and uncertainties of the physical connection between Airborne Imaging Spectrometer (AIS) image data and laboratory/field spectrometer data was tested. The Tuscon AIS-2 image connects to lab reference spectra by an alignment to the image spectral endmembers through a system gain and offset for each band. Images were calibrated to reflectance so as to transform the image into a measure that is independent of the solar radiant flux. This transformation also makes the image spectra directly comparable to data from lab and field spectrometers. A method was tested for calibrating AIS images using the surface as a reference. The surface heterogeneity is defined by lab/field spectral measurements. It was found that the Tuscon AIS-2 image is consistent with each of the initial hypotheses: (1) that the AIS-2 instrument calibration is nearly linear; (2) the spectral variance is caused by sub-pixel mixtures of spectrally distinct materials and shade, and (3) that sub-pixel mixtures can be treated as linear mixtures of pure endmembers. It was also found that the image can be characterized by relatively few endmembers using the AIS-2 spectra
Managing bereavement in the classroom: a conspiracy of silence?
The ways in which teachers in British schools manage bereaved children are under-reported. This article reports the impact of students' bereavement and their subsequent management in primary and secondary school classrooms in Southeast London. Thirteen school staff working in inner-city schools took part in in-depth interviews that focused on the impact of bereaved children on the school and how teachers responded to these children. All respondents had previously had contact with a local child bereavement service that aims to provide support, advice, and consultancy to children, their parents, and teachers. Interviews were audiotaped, transcribed verbatim, and analyzed using ATLAS-ti. Three main themes were identified from analysis of interview data. Firstly, British society, culture, local communities, and the family were significant influences in these teachers' involvement with bereaved students. Secondly, school staff managed bereaved students through contact with other adults and using practical classroom measures such as "time out" cards and contact books. Lastly, teachers felt they had to be strong, even when they were distressed. Surprise was expressed at the mature reaction of secondary school students to deaths of others. The article recommends that future research needs to concentrate on finding the most effective way of supporting routinely bereaved children, their families, and teachers
Recent Decisions
Comments on recent decisions by Larry E. Corr, John J. Malik, Richard E. Shipman, Paul R. Jackiewicz, Mark S. Tolle, Harry L. Buch, Stanley R. Herrlinger, John W, Houck, Donald J. Prebenda, Donald W, Bebenek, Michael C. Dionise, and J. Robert Geiman
Tunable Double Negative Band Structure from Non-Magnetic Coated Rods
A system of periodic poly-disperse coated nano-rods is considered. Both the
coated nano-rods and host material are non-magnetic. The exterior nano-coating
has a frequency dependent dielectric constant and the rod has a high dielectric
constant. A negative effective magnetic permeability is generated near the Mie
resonances of the rods while the coating generates a negative permittivity
through a field resonance controlled by the plasma frequency of the coating and
the geometry of the crystal. The explicit band structure for the system is
calculated in the sub-wavelength limit. Tunable pass bands exhibiting negative
group velocity are generated and correspond to simultaneously negative
effective dielectric permittivity and magnetic permeability. These can be
explicitly controlled by adjusting the distance between rods, the coating
thickness, and rod diameters
Periodic variations in the O-C diagrams of five pulsation frequencies of the DB white dwarf EC 20058-5234
Variations in the pulsation arrival time of five independent pulsation frequencies of the DB white dwarf
EC 20058−5234 individually imitate the effects of reflex motion induced by a planet or companion but are
inconsistent when considered in unison. The pulsation frequencies vary periodically in a 12.9 year cycle and
undergo secular changes that are inconsistent with simple neutrino plus photon-cooling models. The magnitude of
the periodic and secular variations increases with the period of the pulsations, possibly hinting that the corresponding
physical mechanism is located near the surface of the star. The phase of the periodic variations appears coupled
to the sign of the secular variations. The standards for pulsation-timing-based detection of planetary companions
around pulsating white dwarfs, and possibly other variables such as subdwarf B stars, should be re-evaluated.
The physical mechanism responsible for this surprising result may involve a redistribution of angular momentum
or a magnetic cycle. Additionally, variations in a supposed combination frequency are shown to match the sum
of the variations of the parent frequencies to remarkable precision, an expected but unprecedented confirmation
of theoretical predictions.Web of Scienc
Visual Function Questionnaire as an outcome measure for homonymous hemianopia: subscales and supplementary questions, analysis from the VISION trial
Background: We conduct supplementary analyses of the NEI VFQ-25 data to evaluate where changes occurred within subscales of the NEI VFQ-25 leading to change in the composite scores between the three treatment arms, and evaluate the NEI VFQ-25 with and without the Neuro 10 supplement. Methods: A prospective, multicentre, parallel, single-blind, three-arm RCT of fourteen UK acute stroke units was conducted. Stroke survivors with homonymous hemianopia were recruited. Interventions included: Fresnel prisms for minimum 2 h, 5 days/week over 6-weeks (Arm a), Visual search training for minimum 30 min, 5 days/week over 6-weeks (Arm b) and standard care-information only (Arm c). Primary and secondary outcomes (including NEI VFQ-25 data) were measured at baseline, 6, 12 and 26 weeks after randomisation. Results: Eighty seven patients were recruited (69% male; mean age (SD) equal to 69 (12) years). At 26 weeks, outcomes for 24, 24 and 22 patients, respectively, were compared to baseline. NEI VFQ-25 (with and without Neuro 10) responses improved from baseline to 26 weeks with visual search training compared to Fresnel prisms and standard care. In subscale analysis, the most impacted across all treatment arms was ‘driving’ whilst the least impacted were ‘colour vision’ and ‘ocular pain’. Conclusions: Composite scores differed systematically for the NEI VFQ-25 (Neuro 10) versus NEI VFQ-25 at all time points. For subscale scores, descriptive statistics suggest clinically relevant improvement in distance activities and vision-specific dependency subscales for NEI VFQ-25 scores in the visual search treatment arm. Trial Registration: Current Controlled Trials ISRCTN05956042
Phyllostictine A : total synthesis, structural verification and determination of substructure responsible for plant growth inhibition
The first total synthesis of phyllostictine A (PA) is reported, which confirms the structure of this fungal metabolite and its (6S,7R,8S)-stereochemistry. Both synthetic PA and an analogue containing the 5-methylene-1,5-dihydro-2H-pyrrol-2-one nucleus exhibit μM inhibitory activity in root growth assays against Arabidopsis thaliana, indicating that this heterocyclic subunit is key to the herbicidal activity of the natural product
Multi-line Herschel/HIFI observations of water reveal infall motions and chemical segregation around high-mass protostars
(Abridged) We use HIFI maps of the 987 GHz H2O 2(02)-1(11) emission to
measure the sizes and shapes of 19 high-mass protostellar envelopes. To
identify infall, we use HIFI spectra of the optically thin C18O 9-8 and H2O-18
1(11)-0(00) lines. The high-J C18O line traces the warm central material and
redshifted H2O-18 1(11)-0(00) absorption indicates material falling onto the
warm core. We probe small-scale chemical differentiation by comparing H2O 752
and 987 GHz spectra with those of H2O-18.
Our measured radii of the central part of the H2O 2(02)-1(11) emission are
30-40% larger than the predictions from spherical envelope models, and axis
ratios are <2, which we consider good agreement. For 11 of the 19 sources, we
find a significant redshift of the H2O-18 1(11)-0(00) line relative to C18O
9-8. The inferred infall velocities are 0.6-3.2 km/s, and estimated mass inflow
rates range from 7e-5 to 2e-2 M0/yr, with the highest mass inflow rates
occurring toward the sources with the highest masses, and possibly the youngest
ages. The other sources show either expanding motions or H2O-18 lines in
emission. The H2O-18 1(11)-0(00) line profiles are remarkably similar to the
"differences" between the H2O 2(02)-1(11) and 2(11)-2(02) profiles, suggesting
that the H2O-18 line and the H2O 2(02)-1(11) absorption originate just inside
the radius where water evaporates from grains, typically 1000-5000 au from the
center. In some sources, the H2O-18 line is detectable in the outflow, where no
C18O emission is seen.
Together, the H2O-18 absorption and C18O emission profiles show that the
water abundance around high-mass protostars has at least three levels: low in
the cool outer envelope, high within the 100 K radius, and very high in the
outflowing gas. Thus, despite the small regions, the combination of lines
presented here reveals systematic inflows and chemical information about the
outflows.Comment: Accepted for publication in Astronomy & Astrophysics; 10 pages body +
10 pages appendi
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