8,297 research outputs found
Polarization state of the optical near-field
The polarization state of the optical electromagnetic field lying several
nanometers above complex dielectric structures reveals the intricate
light-matter interaction that occurs in this near-field zone. This information
can only be extracted from an analysis of the polarization state of the
detected light in the near-field. These polarization states can be calculated
by different numerical methods well-suited to near--field optics. In this
paper, we apply two different techniques (Localized Green Function Method and
Differential Theory of Gratings) to separate each polarisation component
associated with both electric and magnetic optical near-fields produced by
nanometer sized objects. The analysis is carried out in two stages: in the
first stage, we use a simple dipolar model to achieve insight into the physical
origin of the near-field polarization state. In the second stage, we calculate
accurate numerical field maps, simulating experimental near-field light
detection, to supplement the data produced by analytical models. We conclude
this study by demonstrating the role played by the near-field polarization in
the formation of the local density of states.Comment: 9 pages, 11 figures, accepted for publication in Phys. Rev.
On the Use of a Test to Exhaustion Specific to Tennis (TEST) with Ball Hitting by Elite Players.
PURPOSE: We aimed to a) introduce a new Test to Exhaustion Specific to Tennis (TEST) and compare performance (test duration) and physiological responses to those obtained during the 20-m multistage shuttle test (MSST), and b) determine to which extent those variables correlate with performance level (tennis competitive ranking) for both test procedures.
METHODS: Twenty-seven junior players (8 males, 19 females) members of the national teams of the French Tennis Federation completed MSST and TEST, including elements of the game (ball hitting, intermittent activity, lateral displacement), in a randomized order. Cardiorespiratory responses were compared at submaximal (respiratory compensation point) and maximal loads between the two tests.
RESULTS: At the respiratory compensation point oxygen uptake (50.1 ± 4.7 vs. 47.5 ± 4.3 mL.min(-1).kg(-1), p = 0.02), but not minute ventilation and heart rate, was higher for TEST compared to MSST. However, load increment and physiological responses at exhaustion did not differ between the two tests. Players' ranking correlated negatively with oxygen uptake measured at submaximal and maximal loads for both TEST (r = -0.41; p = 0.01 and -0.55; p = 0.004) and MSST (r = -0.38; P = 0.05 and -0.51; p = 0.1).
CONCLUSION: Using TEST provides a tennis-specific assessment of aerobic fitness and may be used to prescribe aerobic exercise in a context more appropriate to the game than MSST. Results also indicate that VO2 values both at submaximal and maximal load reached during TEST and MSST are moderate predictors of players competitive ranking
The inner environment of Z~CMa: High-Contrast Imaging Polarimetry with NaCo
Context. Z\,CMa is a binary composed of an embedded Herbig Be and an FU Ori
class star separated by au. Observational evidence indicate a complex
environment in which each star has a circumstellar disk and drives a jet, and
the whole system is embedded in a large dusty envelope.
Aims. We aim to probe the circumbinary environment of Z\,CMa in the inner 400
au in scattered light.
Methods. We use high contrast imaging polarimetry with VLT/NaCo at and
bands.
Results. The central binary is resolved in both bands. The polarized images
show three bright and complex structures: a common dust envelope, a sharp
extended feature previously reported in direct light, and an intriguing bright
clump located 0\farcs3 south of the binary, which appears spatially connected
to the sharp extended feature.
Conclusions.We detect orbital motion when compared to previous observations,
and report a new outburst driven by the Herbig star. Our observations reveal
the complex inner environment of Z\,CMa with unprecedented detail and contrast.Comment: Accepted for publication in A&A Letter
Lysine and Energy Levels in Growing and Finishing Swine Diets
High feed pices the past few years have stimulated interest in adding fat to swine rations in an attempt to increase feed efficiency and improve rate of gain. Research has shown that, to get maximum utilization of added energy, protein levels in the diet also must be increased to maintain the calorie to protein ratio. In normal corn-soybean meal rations, lysine has been shown to be the first limiting amino acid. the experiment reported here was conducted to determine the lysine levels necessary in diets with and without fat and their effect on feed consumption, feed efficiency and rate of gain
Lysine-Energy Relationships in Diets for Growing and Finishing Swine
Increasing the energy content of swine diets will generally improve feed efficiency as less feed is consumed and rate of gain is not affected. Limited research with weaned pigs has indicated that the lysine requirement is increased as dietary energy increases when there are relatively large differences in dietary energy increases when there are relatively large differences in dietary energy content. Previous research at this station (A.S. Series 76-33) finishing pigs when 5% fat was included in corn-soybean diet. The experiment reported here was conducted to obtain additional information on the effect of lysine and energy relationships in diets fed to growing and finishing swine
Effect of Supplemental Iron Pig Starter Diets
Iron is added to most trace mineral salts and trace mineral mixtures at low levels. However, it has been reported by some swine producers that they obtain better performance of pigs when fed a relatively high level of iron. Therefore, the objective of this experiment was to determine if there was any benefit of adding iron at levels up to 250 ppm on pig growth, feed efficiency or blood parameters
Bone Development of Pigs as Affected by Calcium and Phosphorus Levels and Floor Types
The relationship between mineral levels in the diets of growing-finishing swine and the type of confinement system in which that are raised is not fully understood. In a previous report (A.S. Series 75-52), we reported the performance data of an experiment designed to provide more information in this area. Reported herein is the information on bone stregnth and bone development as related to floor type and calcium and phosphorus levels in the diet
Young stars in the periphery of the Large Magellanic Cloud
Despite their close proximity, the complex interplay between the two
Magellanic Clouds, the Milky Way, and the resulting tidal features, is still
poorly understood. Recent studies have shown that the Large Magellanic Cloud
(LMC) has a very extended disk strikingly perturbed in its outskirts. We search
for recent star formation in the far outskirts of the LMC, out to ~30 degrees
from its center. We have collected intermediate-resolution spectra of
thirty-one young star candidates in the periphery of the LMC and measured their
radial velocity, stellar parameters, distance and age. Our measurements confirm
membership to the LMC of six targets, for which the radial velocity and
distance values match well those of the Cloud. These objects are all young
(10-50 Myr), main-sequence stars projected between 7 and 13 degrees from the
center of the parent galaxy. We compare the velocities of our stars with those
of a disk model, and find that our stars have low to moderate velocity
differences with the disk model predictions, indicating that they were formed
in situ. Our study demonstrates that recent star formation occurred in the far
periphery of the LMC, where thus far only old objects were known. The spatial
configuration of these newly-formed stars appears ring-like with a radius of 12
kpc, and a displacement of 2.6 kpc from the LMC's center. This structure, if
real, would be suggestive of a star-formation episode triggered by an
off-center collision between the Small Magellanic Cloud and the LMC's disk.Comment: Accepted for publication in MNRA
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