1,083 research outputs found
Infrared Observations of the Helix Planetary Nebula
We have mapped the Helix (NGC 7293) planetary nebula (PN) with the IRAC instrument on the Spitzer Space Telescope. The Helix is one of the closest bright PNs and therefore provides an opportunity to resolve the small-scale structure in the nebula. The emission from this PN in the 5.8 and 8 μm IRAC bands is dominated by the pure rotational lines of molecular hydrogen, with a smaller contribution from forbidden line emission such as [Ar III] in the ionized region. The IRAC images resolve the "cometary knots," which have been previously studied in this PN. The "tails" of the knots and the radial rays extending into the outer regions of the PN are seen in emission in the IRAC bands. IRS spectra on the main ring and the emission in the IRAC bands are consistent with shock-excited H_2 models, with a small (~10%) component from photodissociation regions. In the northeast arc, the H_2 emission is located in a shell outside the Hα emission
Material Induced Anisotropic Damage
The anisotropy in damage can be driven by two different phenomena; anisotropic defor-mation state named Load Induced Anisotropic Damage (LIAD) and anisotropic (shape and/or distribution) second phase particles named Material Induced Anisotropic Damage (MIAD). Most anisotropic damage models are based on LIAD. This work puts emphasis on the presence of MIAD in DP600 steel. Scanning Electron Microscopic (SEM) analysis was carried out on undeformed and deformed tensile specimens. The martensite morphology showed anisotropy in size and orientation. Consequently, significant MIAD was observed in the deformed tensile specimens. A through thickness shear failure is observed in the tensile specimen, which is pulled along the rolling direction (RD), whereas a dominant ductile fracture is observed when pulled perpendicular to RD. The Modified Lemaitre’s (ML) anisotropic damage model is improved to account for MIAD in a phenomenological manner. The MIAD parameters are determined from tensile tests carried out in 0o, 45o and 90o to the RD. The formability of DP600 is lower in the RD compared to that in 90o to the RD, due to the phenomenon of MIAD
Thermal Phase Variations of WASP-12b: Defying Predictions
[Abridged] We report Warm Spitzer full-orbit phase observations of WASP-12b
at 3.6 and 4.5 micron. We are able to measure the transit depths, eclipse
depths, thermal and ellipsoidal phase variations at both wavelengths. The large
amplitude phase variations, combined with the planet's previously-measured
day-side spectral energy distribution, is indicative of non-zero Bond albedo
and very poor day-night heat redistribution. The transit depths in the
mid-infrared indicate that the atmospheric opacity is greater at 3.6 than at
4.5 micron, in disagreement with model predictions, irrespective of C/O ratio.
The secondary eclipse depths are consistent with previous studies. We do not
detect ellipsoidal variations at 3.6 micron, but our parameter uncertainties
-estimated via prayer-bead Monte Carlo- keep this non-detection consistent with
model predictions. At 4.5 micron, on the other hand, we detect ellipsoidal
variations that are much stronger than predicted. If interpreted as a geometric
effect due to the planet's elongated shape, these variations imply a 3:2 ratio
for the planet's longest:shortest axes and a relatively bright day-night
terminator. If we instead presume that the 4.5 micron ellipsoidal variations
are due to uncorrected systematic noise and we fix the amplitude of the
variations to zero, the best fit 4.5 micron transit depth becomes commensurate
with the 3.6 micron depth, within the uncertainties. The relative transit
depths are then consistent with a Solar composition and short scale height at
the terminator. Assuming zero ellipsoidal variations also yields a much deeper
4.5 micron eclipse depth, consistent with a Solar composition and modest
temperature inversion. We suggest future observations that could distinguish
between these two scenarios.Comment: 19 pages, 10 figures, ApJ in press. Improved discussion of gravity
brightenin
Antioxidants for preventing and reducing muscle soreness after exercise
Background
Muscle soreness typically occurs after intense exercise, unaccustomed exercise or actions that involve eccentric contractions
where the muscle lengthens while under tension. It peaks between 24 and 72 hours after the initial bout of exercise. Many
people take antioxidant supplements or antioxidant-enriched foods before and after exercise in the belief that these will
prevent or reduce muscle soreness after exercise.
Objectives
To assess the effects (benefits and harms) of antioxidant supplements and antioxidant-enriched foods for preventing and
reducing the severity and duration of delayed onset muscle soreness following exercise.
Search methods
We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, the Cochrane Central Register of
Controlled Trials, MEDLINE, Embase, SPORTDiscus, trial registers, reference lists of articles and conference proceedings
up to February 2017.
Selection criteria
205 Antioxidants for preventing and reducing muscle soreness after exercise
We included randomised and quasi-randomised controlled trials investigating the effects of all forms of antioxidant
supplementation including specific antioxidant supplements (e.g. tablets, powders, concentrates) and antioxidant-enriched
foods or diets on preventing or reducing delayed onset muscle soreness (DOMS). We excluded studies where antioxidant
supplementation was combined with another supplement.
Data collection and analysis
Two review authors independently screened search results, assessed risk of bias and extracted data from included trials
using a pre-piloted form. Where appropriate, we pooled results of comparable trials, generally using the random-effects
model. The outcomes selected for presentation in the 'Summary of findings' table were muscle soreness, collected at times
up to 6 hours, 24, 48, 72 and 96 hours post-exercise, subjective recovery and adverse effects. We assessed the quality of
the evidence using GRADE.
Main results
Fifty randomised, placebo-controlled trials were included, 12 of which used a cross-over design. Of the 1089 participants,
961 (88.2%) were male and 128 (11.8%) were female. The age range for participants was between 16 and 55 years and
training status varied from sedentary to moderately trained. The trials were heterogeneous, including the timing (pre-exercise
or post-exercise), frequency, dose, duration and type of antioxidant supplementation, and the type of preceding exercise. All
studies used an antioxidant dosage higher than the recommended daily amount. The majority of trials (47) had design
features that carried a high risk of bias due to selective reporting and poorly described allocation concealment, potentially
limiting the reliability of their findings.
We tested only one comparison: antioxidant supplements versus control (placebo). No studies compared high-dose versus
low-dose, where the low-dose supplementation was within normal or recommended levels for the antioxidant involved.
Pooled results for muscle soreness indicated a small difference in favour of antioxidant supplementation after DOMSinducing
exercise at all main follow-ups: up to 6 hours (standardised mean difference (SMD) -0.30, 95% confidence interval
(CI) -0.56 to -0.04; 525 participants, 21 studies; low-quality evidence); at 24 hours (SMD -0.13, 95% CI -0.27 to 0.00; 936
participants, 41 studies; moderate-quality evidence); at 48 hours (SMD -0.24, 95% CI -0.42 to -0.07; 1047 participants, 45
studies; low-quality evidence); at 72 hours (SMD -0.19, 95% CI -0.38 to -0.00; 657 participants, 28 studies; moderate-quality
evidence), and little difference at 96 hours (SMD -0.05, 95% CI -0.29 to 0.19; 436 participants, 17 studies; low-quality
evidence). When we rescaled to a 0 to 10 cm scale in order to quantify the actual difference between groups, we found that
the 95% CIs for all five follow-up times were all well below the minimal important difference of 1.4 cm: up to 6 hours (MD
-0.52, 95% CI -0.95 to -0.08); at 24 hours (MD -0.17, 95% CI -0.42 to 0.07); at 48 hours (MD -0.41, 95% CI -0.69 to -0.12); at
72 hours (MD -0.29, 95% CI -0.59 to 0.02); and at 96 hours (MD -0.03, 95% CI -0.43 to 0.37). Thus, the effect sizes
suggesting less muscle soreness with antioxidant supplementation were very unlikely to equate to meaningful or important
differences in practice. Neither of our subgroup analyses to examine for differences in effect according to type of DOMSinducing
exercise (mechanical versus whole body aerobic) or according to funding source confirmed subgroup differences.
Sensitivity analyses excluding cross-over trials showed that their inclusion had no important impact on results.
None of the 50 included trials measured subjective recovery (return to previous activities without signs or symptoms).
There is very little evidence regarding the potential adverse effects of taking antioxidant supplements as this outcome was
reported in only nine trials (216 participants). From the studies that did report adverse effects, two of the nine trials found
adverse effects. All six participants in the antioxidant group of one trial had diarrhoea and four of these also had mild
indigestion; these are well-known side effects of the particular antioxidant used in this trial. One of 26 participants in a second
trial had mild gastrointestinal distress.
Authors' conclusions
There is moderate to low-quality evidence that high dose antioxidant supplementation does not result in a clinically relevant
reduction of muscle soreness after exercise at up to 6 hours or at 24, 48, 72 and 96 hours after exercise. There is no
evidence available on subjective recovery and only limited evidence on the adverse effects of taking antioxidant
supplements. The findings of, and messages from, this review provide an opportunity for researchers and other stakeholders
to come together and consider what are the priorities, and underlying justifications, for future research in this area
Antioxidants for preventing and reducing muscle soreness after exercise: a Cochrane systematic review
Objective: To determine whether antioxidants supplements and antioxidant-enriched foods can prevent or reduce delayed onset muscle soreness after exercise.
Methods: We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, SPORTDiscus, trial registers, reference lists of articles and conference proceedings up to February 2017
Results: In total, 50 studies were included in this review which included a total of 1089 participants (961 were male and 128 were female) with an age range between 16 and 55 years. All studies used an antioxidant dosage higher than the recommended daily amount. The majority of trials (47) had design features that carried a high risk of bias due to selective reporting and poorly described allocation concealment, potentially limiting the reliability of their findings. We rescaled to a 0 to 10 cm scale in order to quantify the actual difference between groups and we found that the 95% CIs for all five follow-up times were all well below the minimal important difference of 1.4 cm: up to 6 hours (MD -0.52, 95% CI -0.95 to -0.08); at 24 hours (MD -0.17, 95% CI -0.42 to 0.07); at 48 hours (MD -0.41, 95% CI -0.69 to -0.12); at 72 hours (MD -0.29, 95% CI -0.59 to 0.02); and at 96 hours (MD -0.03, 95% CI - 0.43 to 0.37). Thus, the effect sizes suggesting less muscle soreness with antioxidant supplementation were very unlikely to equate to meaningful or important differences in practice.
Conclusions: There is moderate to low-quality evidence that high dose antioxidant supplementation does not result in a clinically relevant reduction
of muscle soreness after exercise at up to 6 hours or at 24, 48, 72 and 96 hours after exercise. There is no evidence available on subjective recovery and only limited evidence on the adverse effects of taking antioxidant supplements
Radial Bargmann representation for the Fock space of type B
Let be the probability and orthogonality measure for the
-Meixner-Pollaczek orthogonal polynomials, which has appeared in
\cite{BEH15} as the distribution of the -Gaussian process (the
Gaussian process of type B) over the -Fock space (the Fock space of
type B). The main purpose of this paper is to find the radial Bargmann
representation of . Our main results cover not only the
representation of -Gaussian distribution by \cite{LM95}, but also of
-Gaussian and symmetric free Meixner distributions on . In
addition, non-trivial commutation relations satisfied by -operators
are presented.Comment: 13 pages, minor changes have been mad
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