9,765 research outputs found
Geometrically induced modification of surface plasmons in the optical and telecom regimes
We demonstrate that the introduction of a subwavelength periodic modulation
into a metallic structure strongly modifies the guiding characteristics of the
surface plasmon modes supported by the system. Moreover, it is also shown how a
new type of a tightly confined surface plasmon polariton mode can be created by
just milling a periodic corrugation into a metallic ridge placed on top of a
metal surface
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Predicting Progression in Parkinson's Disease Using Baseline and 1-Year Change Measures.
BackgroundImproved prediction of Parkinson's disease (PD) progression is needed to support clinical decision-making and to accelerate research trials.ObjectivesTo examine whether baseline measures and their 1-year change predict longer-term progression in early PD.MethodsParkinson's Progression Markers Initiative study data were used. Participants had disease duration â¤2 years, abnormal dopamine transporter (DAT) imaging, and were untreated with PD medications. Baseline and 1-year change in clinical, cerebrospinal fluid (CSF), and imaging measures were evaluated as candidate predictors of longer-term (up to 5 years) change in Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) score and DAT specific binding ratios (SBR) using linear mixed-effects models.ResultsAmong 413 PD participants, median follow-up was 5 years. Change in MDS-UPDRS from year-2 to last follow-up was associated with disease duration (β=â0.351; 95% CIâ=â0.146, 0.555), male gender (β=â3.090; 95% CIâ=â0.310, 5.869), and baseline (β=â-0.199; 95% CIâ=â-0.315, -0.082) and 1-year change (β=â0.540; 95% CIâ=â0.423, 0.658) in MDS-UPDRS; predictors in the model accounted for 17.6% of the variance in outcome. Predictors of percent change in mean SBR from year-2 to last follow-up included baseline rapid eye movement sleep behavior disorder score (β=â-0.6229; 95% CIâ=â-1.2910, 0.0452), baseline (β=â7.232; 95% CIâ=â2.268, 12.195) and 1-year change (β=â45.918; 95% CIâ=â35.994,55.843) in mean striatum SBR, and 1-year change in autonomic symptom score (β=â-0.325;95% CIâ=â-0.695, 0.045); predictors in the model accounted for 44.1% of the variance.ConclusionsBaseline clinical, CSF, and imaging measures in early PD predicted change in MDS-UPDRS and dopamine-transporter binding, but the predictive value of the models was low. Adding the short-term change of possible predictors improved the predictive value, especially for modeling change in dopamine-transporter binding
Light Neutralinos as Dark Matter in the Unconstrained Minimal Supersymmetric Standard Model
The allowed parameter space for the lightest neutralino as the dark matter is
explored using the Minimal Supersymmetric Standard Model as the low-energy
effective theory without further theoretical constraints such as GUT. Selecting
values of the parameters which are in agreement with present experimental
limits and applying the additional requirement that the lightest neutralino be
in a cosmologically interesting range, we give limits on the neutralino mass
and composition. A similar analysis is also performed implementing the grand
unification constraints. The elastic scattering cross section of the selected
neutralinos on Al and on other materials for dark matter experiments is
discussed.Comment: Submitted to Astroparticle Physics, 19 Feb. 96, Latex 23 pages with
24 figures in a gzip compressed file FIGURE.PS.GZ available via anonymous ftp
from ftp://iws104.mppmu.mpg.de/pub/gabutt
On the Neutral Gas Content and Environment of NGC 3109 and the Antlia Dwarf Galaxy
As part of a continuing survey of nearby galaxies, we have mapped the neutral
gas content of the low surface brightness, Magellanic-type galaxy NGC 3109 ---
and its environment, including the Antlia dwarf galaxy --- at unprecedented
velocity resolution and brightness sensitivity. The HI mass of NGC 3109 is
measured to be (3.8 +/- 0.5) x 10^8 Msun. A substantial warp in the disk of NGC
3109 is detected in the HI emission image in the form of an extended low
surface brightness feature. We report a positive detection in HI of the nearby
Antlia dwarf galaxy, and measure its total neutral gas mass to be (6.8 +/- 1.4)
x 10^5 Msun. We show the warp in NGC 3109 to lie at exactly the same radial
velocity as the gas in the Antlia dwarf galaxy and speculate that Antlia
disturbed the disk of NGC 3109 during a mild encounter ~1 Gyr in the past. HI
data for a further eight galaxies detected in the background are presented.Comment: Accepted for publication in A
The Effect of a Mycotoxin Deactivation Product on Growth of Juvenile Rainbow Trout Fed Distillers Dried Grains
Distillers dried grains (DDG) with solubles (DDGS) is a product that has shown potential as a protein source for some fish species, but high inclusion rates of DDGS have not always been successfully achieved for Rainbow Trout Oncorhynchus mykiss. Our objective was to determine whether inclusion of a mycotoxin deactivation product (Biofix Plus) could improve the ability of high-protein DDG (HPDDG) to replace a portion of the fish meal in diets for Rainbow Trout. The 2 à 2 factorial feeding trial examined protein source (menhaden fish meal [MFM] or HPDDG) with or without Biofix Plus. A control diet (42% digestible protein, 20% crude lipid, 25% MFM) was compared to a test diet in which HPDDG replaced 12% of the total MFM on a digestible-protein basis (24% HPDDG inclusion). Diets were fed to juvenile Rainbow Trout (initial weight: mean ¹ SE = 30.5 ¹ 1.6 g) in four replicate tanks per treatment for 9 weeks in a 15°C recirculating system. At the conclusion of the feeding trial, we observed no negative effects of fish meal replacement on growth or feed conversion ratio; no benefit of Biofix Plus supplementation was observed. These data indicate that when Rainbow Trout diets containing a high-quality DDGS product are balanced for digestible protein, lysine, methionine, and threonine, dietary fish meal levels can be successfully reduced to 13% without compromising growth and without the need for mycotoxin deactivator inclusion
A catalogue of bright (K <9) M dwarfs
Using the Position and Proper Motion Extended-L (PPMXL) catalogue, we have used optical and near-infrared colour cuts together with a reduced proper motion cut to find bright M dwarfs for future exoplanet transit studies. PPMXL's low proper motion uncertainties allow us to probe down to smaller proper motions than previous similar studies. We have combined unique objects found with this method to that of previous work to produce 8479 K <9 M dwarfs. Low-resolution spectroscopy was obtained of a sample of the objects found using this selection method to gain statistics on their spectral type and physical properties. Results show a spectral-type range of K7-M4V. This catalogue is the most complete collection of K <9 M dwarfs currently available and is made available here.Peer reviewe
HIPASS Detection of an Intergalactic Gas Cloud in the NGC 2442 Group
We report the discovery, from the HI Parkes All-Sky Survey (HIPASS), of a gas
cloud associated with the asymmetric spiral galaxy NGC 2442. This object,
designated HIPASS J0731-69, contains ~10^9 M_sun of HI, or nearly one-third as
much atomic gas as NGC 2442 itself. No optical counterpart to any part of
HIPASS J0731-69 has yet been identified, consistent with the gas being diffuse,
and with its stream-like kinematics. If the gas in HIPASS J0731-69 was once
part of NGC 2442, then it was most likely a fairly recent tidal encounter with
a moderately massive companion which tore it loose, although the possibility of
ram-pressure stripping cannot be ruled out. This discovery highlights the
potential of the HIPASS data for yielding new clues to the nature of some of
the best-known galaxies in the local universe.Comment: 8 pages, 4 figures, uses "emulateapj5.sty". Accepted for publication
in ApJ, Vol. 555, 1 July 2001. Figs 1 and 2 included as JPE
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