759 research outputs found
Origin and assessment of bruises in beef cattle at slaughter
Studies of bruises, as detected on carcasses at the slaughterhouse, may provide useful information about the traumatic situations the animals endure during the pre-slaughter period. In this paper, we review scientific data on the prevalence, risk factors and estimation of the age of bruises in beef cattle. Risk factors such as animal characteristics, transport conditions, stocking density, livestock auction and handling of the animals are discussed. Investigation of the age of bruises could provide information on when in the meat chain bruises occur and, could help to pinpoint where preventive measures should be taken, from the stage of collecting the animals on the farm until slaughter. We review the methods available to assess the age of the bruises; data on human forensic research are also included. The feasibility to identify traumatic episodes during the pre-slaughter period, in order to improve animal welfare is discusse
Measurements of the First RF Prototype of the SPIRAL2 Single Bunch Selector
WEPD062International audienceThe single bunch selector of the Spiral2 driver uses 100 travelling wave electrodes driven by fast pulse generators. A 2.5 kV, 1 kW feed-through and a vacuum chamber housing the water cooled electrodes have been designed and built. The paper reviews the whole design and reports the results of first RF and power measurements
The LEBT Chopper for the Spiral 2 Project
International audienceThe Spiral 2 driver uses a slow chopper situated in the common section of the low energy beam transport line to change the beam intensity, to cut off the beam in case of critical loss and to avoid hitting the wheel structure of rotating targets. The device has to work up to 10 kV, 1 kHz repetition frequency rate and its design is based on standard power circuits, custom alarm board and vacuum feed-through. The paper summarizes the design principles and describes the test results of the final device which has been installed on the beam line test bench
Characteristics of bruises in carcasses of cows sourced from farms or from livestock markets
Bruises in cattle develop after the application of force, and they provide evidence for sub-optimal animal welfare. The aim of this study was to describe the gross characteristics of bruises in cows arriving at the slaughterhouse directly from farms or through the livestock market. The number of bruises and their distribution on the carcass as well as their severity, shape, size and colour were assessed post mortem in a slaughterhouse in Chile. A total of 258 cow carcasses were evaluated, and a total of 846 bruises were found on 243 of the carcasses. Cows that had passed through a livestock market (M-carcasses) had in total 563 bruises (mean 3.8 bruises/carcass, s.d. 2.0), whereas cows transported directly from farms (F-carcasses) had in total 283 bruises (mean 2.5 bruises/carcass, s.d. 1.8). The backs of F-carcasses had twice as many bruises as M-carcasses (32.9% and 16.2%, respectively), whereas bruises in the rib area were more frequently observed in M-carcasses (13.1%) than in F-carcasses (8.1%). Superficial bruises (grade 1) were the most frequently observed (66.2% of all bruises). Regarding the size of the bruises, 64 (7.6%) were classified as large, 271 (32.0%) as medium and 511 (60.4%) as small. Irregularly shaped bruises were the most frequent (91.1%, n = 771), followed by linear (3.8%, n = 32), circular (3.1%, n = 26) and tramline-shaped bruises (1.9%, n = 16). The latter were noticed only in M-carcasses, which may indicate that these animals were beaten more frequently with sticks or other rod-shaped objects. Fresh, bright red-coloured bruises were found more frequently on all the animals (69.5% from farms and 70.5% from market) compared with bluish (29.7% and 29.3%, respectively) and yellow bruises (0.4% and 0.2%, respectively). The method of selling was significantly associated with the number of bruises on the carcass (P <0.001) and the anatomical site (P <0.05), but not with the severity, shape and colour of the bruises. Increased fat coverage reduced the severity of bruises (P <0.001). This study shows that, in Chile, market animals have more bruises than those sourced directly from farms, and their distribution is different. More information about the causes of infliction may help reduce bruises and it may also improve their welfare. Further studies are required to elucidate whether the causes of the high bruising in the case of animals passing through markets are related only to extra handling (repeated loading, unloading, transportation, eventual mixing) or to the way of handling by personnel and inadequate desig
Measuring Black Hole Spin using X-ray Reflection Spectroscopy
I review the current status of X-ray reflection (a.k.a. broad iron line)
based black hole spin measurements. This is a powerful technique that allows us
to measure robust black hole spins across the mass range, from the stellar-mass
black holes in X-ray binaries to the supermassive black holes in active
galactic nuclei. After describing the basic assumptions of this approach, I lay
out the detailed methodology focusing on "best practices" that have been found
necessary to obtain robust results. Reflecting my own biases, this review is
slanted towards a discussion of supermassive black hole (SMBH) spin in active
galactic nuclei (AGN). Pulling together all of the available XMM-Newton and
Suzaku results from the literature that satisfy objective quality control
criteria, it is clear that a large fraction of SMBHs are rapidly-spinning,
although there are tentative hints of a more slowly spinning population at high
(M>5*10^7Msun) and low (M<2*10^6Msun) mass. I also engage in a brief review of
the spins of stellar-mass black holes in X-ray binaries. In general,
reflection-based and continuum-fitting based spin measures are in agreement,
although there remain two objects (GROJ1655-40 and 4U1543-475) for which that
is not true. I end this review by discussing the exciting frontier of
relativistic reverberation, particularly the discovery of broad iron line
reverberation in XMM-Newton data for the Seyfert galaxies NGC4151, NGC7314 and
MCG-5-23-16. As well as confirming the basic paradigm of relativistic disk
reflection, this detection of reverberation demonstrates that future large-area
X-ray observatories such as LOFT will make tremendous progress in studies of
strong gravity using relativistic reverberation in AGN.Comment: 19 pages. To appear in proceedings of the ISSI-Bern workshop on "The
Physics of Accretion onto Black Holes" (8-12 Oct 2012). Revised version adds
a missing source to Table 1 and Fig.6 (IRAS13224-3809) and corrects the
referencing of the discovery of soft lags in 1H0707-495 (which were in fact
first reported in Fabian et al. 2009
Evidence that the Bursting Component of the X-ray Radiation From 3C 111 Originates in the PC-Scale Jet
Evidence is presented indicating that the bursting component of the X-ray
radiation detected in the nuclear region of the active radio galaxy 3C 111
comes from the blobs ejected in the pc-scale jet and not from the accretion
disc. After each new outburst the radio flux density associated with it
increases to a peak in ~1 year and then subsides over a period of 1-2 years
with the flux falling off exponentially as the blob moves outward and
dissipates. Similar peaks (bursts) are seen in the X-ray light curve and a
cross-correlation between the two shows a very high correlation with the X-ray
peaks leading the radio peaks by ~100 days. A second cross-correlation, this
time between the radio event start times and the X-ray light curve, also shows
a significant correlation. When this is taken together with the long (~1 yr)
delay between the start of each ejection event and its associated X-ray peak it
indicates that this bursting component of the X-ray flux must be associated
with the ejected blobs in the pc-scale jet and not with the accretion disc.
Because X-ray telescopes do not have the resolution required to resolve the
accretion disc area from the pc-scale jet, this paper is the first to present
observational evidence that can pinpoint the point of origin of at least those
long-timescale X-ray bursts with durations of 1-3 yrs.Comment: 11 pages, 8 Figures. Accepted for publication in Astrophysics and
Space Scienc
An overview of jets and outflows in stellar mass black holes
In this book chapter, we will briefly review the current empirical
understanding of the relation between accretion state and and outflows in
accreting stellar mass black holes. The focus will be on the empirical
connections between X-ray states and relativistic (`radio') jets, although we
are now also able to draw accretion disc winds into the picture in a systematic
way. We will furthermore consider the latest attempts to measure/order jet
power, and to compare it to other (potentially) measurable quantities, most
importantly black hole spin.Comment: Accepted for publication in Space Science Reviews. Also to appear in
the Space Sciences Series of ISSI - The Physics of Accretion on to Black
Holes (Springer Publisher
Low-Luminosity Accretion in Black Hole X-ray Binaries and Active Galactic Nuclei
At luminosities below a few percent of Eddington, accreting black holes
switch to a hard spectral state which is very different from the soft
blackbody-like spectral state that is found at higher luminosities. The hard
state is well-described by a two-temperature, optically thin, geometrically
thick, advection-dominated accretion flow (ADAF) in which the ions are
extremely hot (up to K near the black hole), the electrons are also
hot ( K), and thermal Comptonization dominates the X-ray
emission. The radiative efficiency of an ADAF decreases rapidly with decreasing
mass accretion rate, becoming extremely low when a source reaches quiescence.
ADAFs are expected to have strong outflows, which may explain why relativistic
jets are often inferred from the radio emission of these sources. It has been
suggested that most of the X-ray emission also comes from a jet, but this is
less well established.Comment: To appear in "From X-ray Binaries to Quasars: Black Hole Accretion on
All Mass Scales" edited by T. Maccarone, R. Fender, L. Ho, to be published as
a special edition of "Astrophysics and Space Science" by Kluwe
Black Hole Spin via Continuum Fitting and the Role of Spin in Powering Transient Jets
The spins of ten stellar black holes have been measured using the
continuum-fitting method. These black holes are located in two distinct classes
of X-ray binary systems, one that is persistently X-ray bright and another that
is transient. Both the persistent and transient black holes remain for long
periods in a state where their spectra are dominated by a thermal accretion
disk component. The spin of a black hole of known mass and distance can be
measured by fitting this thermal continuum spectrum to the thin-disk model of
Novikov and Thorne; the key fit parameter is the radius of the inner edge of
the black hole's accretion disk. Strong observational and theoretical evidence
links the inner-disk radius to the radius of the innermost stable circular
orbit, which is trivially related to the dimensionless spin parameter a_* of
the black hole (|a_*| < 1). The ten spins that have so far been measured by
this continuum-fitting method range widely from a_* \approx 0 to a_* > 0.95.
The robustness of the method is demonstrated by the dozens or hundreds of
independent and consistent measurements of spin that have been obtained for
several black holes, and through careful consideration of many sources of
systematic error. Among the results discussed is a dichotomy between the
transient and persistent black holes; the latter have higher spins and larger
masses. Also discussed is recently discovered evidence in the transient sources
for a correlation between the power of ballistic jets and black hole spin.Comment: 30 pages. Accepted for publication in Space Science Reviews. Also to
appear in hard cover in the Space Sciences Series of ISSI "The Physics of
Accretion onto Black Holes" (Springer Publisher). Changes to Sections 5.2,
6.1 and 7.4. Section 7.4 responds to Russell et al. 2013 (MNRAS, 431, 405)
who find no evidence for a correlation between the power of ballistic jets
and black hole spi
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