8,886 research outputs found
Promoting kangaroo as a sustainable option for meat production on the rangelands of Australia
Implications
âąAs kangaroo meat is sourced from native wildlife, conservation of the species is important in developing sustainable meat harvesting. Landholders, conservationists, and commercial meat producers need to work together to achieve this goal.
âąThe production of high quality meat products from field-harvested carcasses can be augmented through a better understanding of the impact that field conditions and carcass handling have on final meat eating quality.
âąFood safety is also paramount, with measures taken to minimize the impacts of parasitism and microbial contamination. Any breaches of inspection protocols can only serve to undermine consumer confidence and viability of the industry
Laser-induced break-up of water jet waveguide
In this article, an optical method to control the break-up of high-speed liquid jets is proposed. The method consists of focusing the light of a pulsed laser source into the jet behaving as a waveguide. Experiments were performed with the help of a Q-switched frequency doubled Nd:Yag laser (λ=532nm). The jet diameter was 48”m and jet velocities from 100 to 200m/s. To study the laser-induced water jet break-up, observations of the jet coupled with the high power laser were performed for variable coupling and jet velocity conditions. Experimentally determined wavelength and growth rate of the laser-generated disturbance were also compared with the ones predicted by linear stability theory of free jet
Particle Aggregation in a turbulent Keplerian flow
In the problem of planetary formation one seeks a mechanism to gather small
solid particles together into larger accumulations of solid matter. Here we
describe a scenario in which turbulence mediates this process by aggregating
particles into anticyclonic regions. If, as our simulations suggest,
anticyclonic vortices form as long-lived coherent structures, the process
becomes more powerful because such vortices trap particles effectively. Even if
the turbulence is decaying, following the upheaval that formed the disk, there
is enough time to make the dust distribution quite lumpy.Comment: 16 pages, 9 figure
Standard Solar models in the Light of New Helioseismic Constraints II. Mixing Below the Convective Zone
In previous work, we have shown that recent updated standard solar models
cannot reproduce the radial profile of the sound speed at the base of the
convective zone (CZ) and fail to predict the Li7 depletion. In parallel,
helioseismology has shown that the transition from differential rotation in the
CZ to almost uniform rotation in the radiative solar interior occurs in a
shallow layer called the tachocline. This layer is presumably the seat of large
scale circulation and of turbulent motions. Here, we introduce a macroscopic
transport term in the structure equations, which is based on a hydrodynamical
description of the tachocline proposed by Spiegel and Zahn, and we calculate
the mixing induced within this layer. We discuss the influence of different
parameters that represent the tachocline thickness, the Brunt-Vaissala
frequency at the base of the CZ, and the time dependence of this mixing process
along the Sun's evolution. We show that the introduction of such a process
inhibits the microscopic diffusion by about 25%. Starting from models including
a pre-main sequence evolution, we obtain: a) a good agreement with the observed
photospheric chemical abundance of light elements such as He3, He4, Li7 and
Be9, b) a smooth composition gradient at the base of the CZ, and c) a
significant improvement of the sound speed square difference between the
seismic sun and the models in this transition region, when we allow the
phostospheric heavy element abundance to adjust, within the observational
incertitude, due to the action of this mixing process. The impact on neutrino
predictions is also discussed.Comment: 15 pages, 7 figures, to be published in ApJ (used emulateapj style
for latex2e). New email for A. S. Brun: [email protected]
Instabilities in the Envelopes and Winds of Very Massive Stars
The high luminosity of Very Massive Stars (VMS) means that radiative forces
play an important, dynamical role both in the structure and stability of their
stellar envelope, and in driving strong stellar-wind mass loss. Focusing on the
interplay of radiative flux and opacity, with emphasis on key distinctions
between continuum vs. line opacity, this chapter reviews instabilities in the
envelopes and winds of VMS. Specifically, we discuss how: 1) the iron opacity
bump can induce an extensive inflation of the stellar envelope; 2) the density
dependence of mean opacity leads to strange mode instabilities in the outer
envelope; 3) desaturation of line-opacity by acceleration of near-surface
layers initiates and sustains a line-driven stellar wind outflow; 4) an
associated line-deshadowing instability leads to extensive small-scale
structure in the outer regions of such line-driven winds; 5) a star with
super-Eddington luminosity can develop extensive atmospheric structure from
photon bubble instabilities, or from stagnation of flow that exceeds the
"photon tiring" limit; 6) the associated porosity leads to a reduction in
opacity that can regulate the extreme mass loss of such continuum-driven winds.
Two overall themes are the potential links of such instabilities to Luminous
Blue Variable (LBV) stars, and the potential role of radiation forces in
establishing the upper mass limit of VMS.Comment: 44 pages, 13 figures. Chapter to appear in the book "Very Massive
Stars in the Local Universe", Springer, J.S. Vink, e
Exceptional Laguerre and Jacobi polynomials and the corresponding potentials through Darboux-Crum Transformations
Simple derivation is presented of the four families of infinitely many shape
invariant Hamiltonians corresponding to the exceptional Laguerre and Jacobi
polynomials. Darboux-Crum transformations are applied to connect the well-known
shape invariant Hamiltonians of the radial oscillator and the
Darboux-P\"oschl-Teller potential to the shape invariant potentials of
Odake-Sasaki. Dutta and Roy derived the two lowest members of the exceptional
Laguerre polynomials by this method. The method is expanded to its full
generality and many other ramifications, including the aspects of generalised
Bochner problem and the bispectral property of the exceptional orthogonal
polynomials, are discussed.Comment: LaTeX2e with amsmath, amssymb, amscd 26 pages, no figure
Gastrointestinal symptom severity in irritable bowel syndrome, inflammatory bowel disease and the general population
BackgroundIrritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) patients report similar gastrointestinal (GI) symptoms, yet comparisons of symptom severity between groups and with the general population (GP) are lacking.MethodsWe compared PatientâReported Outcomes Measurement Information System (PROMISÂź) GI symptom scales measuring gastroâesophageal reflux (GER), disrupted swallowing, diarrhea, bowel incontinence, nausea/vomiting, constipation, belly pain, and gas/bloating in: (i) USA GP sample, (ii) IBS patients, and (iii) IBD patients from tertiary care and community populations. Symptom severity scores were based on Tâscore metric with mean 50±10 (standard deviation) relative to the GP.Key ResultsOf 1643 patients enrolled, there were 253 IBS patients (68% F, mean age 45±15 years), 213 IBD patients (46% F, mean age 41±14 years), and 1177 GP subjects (57% F, mean age 46±16 years). IBS patients reported greater severity of GER, disrupted swallowing, nausea/vomiting, belly pain, gas/bloating, and constipation symptoms than their IBD counterparts (all P<.05). Compared to the GP, IBD patients had worse belly pain, gas/bloating, diarrhea, and bowel incontinence, but less severe GER and disrupted swallowing (all P<.05), and IBS patients had more severe nausea/vomiting, belly pain, gas/bloating, and constipation (all P<.05). Women had more severe belly pain and gas/bloating than men, whereas men had more severe bowel incontinence (all P<.05).Conclusion & InferencesIBS and IBD are associated with more severe GI symptoms compared to the GP excluding esophageal symptoms. Unlike IBD, IBS is not characterized by observable GI inflammation but patients report more severe upper and lower GI symptoms.The PROMIS GI scales were used to determine gastrointestinal symptoms severity in patients. Unlike IBD, IBS is not characterized by observable gastrointestinal inflammation, but patients report more severe upper and lower gastrointestinal symptoms.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136712/1/nmo13003.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136712/2/nmo13003_am.pd
The effects of related experiments
The effects of the experiment itself upon the obtained results and,
especially, the influence of a large number of experiments are extensively
discussed in the literature. We show that the important factor that stands at
the basis of these effects is that the involved experiments are related and not
independent and detached from each other. This relationship takes, as shown
here, different forms for different situations and is found in entirely
different physical regimes such as the quantum and classical ones.Comment: 27 pages, 6 figures, 1 table. One figure removed. Some former text
has been rewritten in compact and clearer way. Also the title change
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