1,374 research outputs found
Bottlenose Dolphins, Tursiops truncatus, Removing By-catch from Prawn-trawl Codends During Fishing in New South Wales, Australia
During a fishing trip to record video footage of fish escaping from a by-catch reducing device located in a commercial prawn trawl, two bottlenose dolphins, Tursiops truncatus, were observed to actively manipulate the codend at the seabed, removing and consuming components of catch (mostly juvenile whiting, Sillago spp.). The observed feeding pattern suggests a well established behavioral response to trawling activities and is discussed with
respect to (1) the potential nutritional benefit that dolphins may derive from such activities and (2) the effects that scavenging may have on selectivity of the gear
Capturing the scale and pattern of recurrent care proceedings: initial observations from a feasibility study
This article reports the initial findings of a feasibility study that has captured the scale and pattern of recurrent care proceedings. Although frontline professionals have reported long-standing concerns about the repeat clients of public law proceedings, prior to the study we report, the scale of the problem has been unknown. With funding from the Nuffield Foundation and support from the Child and Family Court Advisory Service (CAFCASS) and the President of the Family Division, the research team has arrived at a first estimate of prevalence, confirming that recurrence is a sizeable problem for the English family court. Based on cases that completed during the observational window 2007-2013 (calendar years), 7,143 birth mothers appeared in 15,645 recurrent care applications concerning 22,790 infants and children. Moreover, the study most likely underestimates recurrence, because reliable data concerning completed cases is not available before 2007. Initial observations are that the spacing between recurrent care proceedings is very short, which raises searching questions about prevention. Where episodes of care proceedings follow in swift succession, most likely prompted by the birth of another infant, this affords mothers little opportunity to effect change. Unless, this ‘status quo’ is tackled, it is difficult to envisage how vulnerable birth mothers can exit this cycle. Preliminary recommendations are made in respect of policy and practice change
Dimensional renormalization: ladders to rainbows
Renormalization factors are most easily extracted by going to the massless
limit of the quantum field theory and retaining only a single momentum scale.
We derive factors and renormalized Green functions to all orders in
perturbation theory for rainbow graphs and vertex (or scattering diagrams) at
zero momentum transfer, in the context of dimensional renormalization, and we
prove that the correct anomalous dimensions for those processes emerge in the
limit D -> 4.Comment: RevTeX, no figure
Ιδιωτικής χρήσης αυτοκίνητα στης Αθήνα: μια αυτοπαλίνδρομη διανυσματική προσέγγιση (VAR)
The natural mortality (M) and purse-seine catchability and selectivity were
estimated for Trachurus novaezelandiae, Richardson, 1843 (yellowtail scad)-a
small inshore pelagic species harvested off south-eastern Australia. Hazard
functions were applied to two decades of data describing catches (mostly stable
at a mean +- SE of 315 +- 14 t p.a.) and effort (declining from a maximum of
2289 to 642 boat days between 1999/00 and 2015/16) and inter-dispersed (over
nine years) annual estimates of size-at-age (0+ to 18 years) to enable survival
analysis. The data were best described by a model with eight parameters,
including catchability (estimated at < 0.1 x 10-7 boat day-1), M (0.22 year-1)
and variable age-specific selection up to 6 years with a 50% retention among
5-year olds (larger than the estimated age at maturation). The low catchability
implied minimal fishing mortality by the purse-seine fleet. Ongoing monitoring
and applied gear-based studies are required to validate purse-seine
catchability and selectivity, but the data nevertheless imply T. novaezelandiae
could incur substantial additional fishing effort and, in doing, so alleviate
pressure on other regional small pelagics
Lectures on multiloop calculations
I discuss methods of calculation of propagator diagrams (massless, those of
Heavy Quark Effective Theory, and massive on-shell diagrams) up to 3 loops.
Integration-by-parts recurrence relations are used to reduce them to linear
combinations of basis integrals. Non-trivial basis integrals have to be
calculated by some other method, e.g., using Gegenbauer polynomial technique.
Many of them are expressed via hypergeometric functions; in the massless and
HQET cases, their indices tend to integers at . I discuss the
algorithm of their expansion in , in terms of multiple
values. These lectures were given at Calc-03 school, Dubna, 14--20 June 2003.Comment: 52 pages, 49 figures. Lectures at Calc-03 school, Dubna, 14--20 June
2003. v2: 2 references added, minor typos corrected. v3: methodical
improvements, typo in eq. (3.19) corrected, 2 references adde
A faint galaxy redshift survey to B=24
Using the multislit LDSS-2 spectrograph on the {\it William Herschel
Telescope} we have completed a redshift survey in the magnitude range which has produced 73 redshifts representing a 73\% complete sample
uniformly-selected from four deep fields at high Galactic latitude. The survey
extends out to and includes the highest redshift galaxy () yet
discovered in a field sample. The median redshift, \zmed=0.46, and form of
the redshift distribution constitute compelling evidence against simple
luminosity evolution as an explanation of the large excess of faint galaxies
(2--4 no-evolution) seen in this magnitude range. Rather we
identify the excess population as blue objects with and \,
luminosities similar to local galaxies indicating a dramatic decrease in
the density of such objects over the last Hubble time, confirming the trends
found in brighter redshift surveys. We also find a marked absence of {\it very}
low redshift galaxies (0.1) at faint limits, severely constraining any
significant steepening of the local field galaxy luminosity function at low
luminosities.Comment: uuencoded compressed postscript. The preprint are also available at
URL http://www.ast.cam.ac.uk/preprint/PrePrint.htm
Master integrals for massive two-loop Bhabha scattering in QED
We present a set of scalar master integrals (MIs) needed for a complete
treatment of massive two-loop corrections to Bhabha scattering in QED,
including integrals with arbitrary fermionic loops. The status of analytical
solutions for the MIs is reviewed and examples of some methods to solve MIs
analytically are worked out in more detail. Analytical results for the pole
terms in epsilon of so far unknown box MIs with five internal lines are given.Comment: 23 pages, 5 tables, 12 figures, references added, appendix B enlarge
A Free-Form Lensing Grid Solution for A1689 with New Mutiple Images
Hubble Space Telescope imaging of the galaxy cluster Abell 1689 has revealed
an exceptional number of strongly lensed multiply-imaged galaxies, including
high-redshift candidates. Previous studies have used this data to obtain the
most detailed dark matter reconstructions of any galaxy cluster to date,
resolving substructures ~25 kpc across. We examine Abell 1689 (hereafter,
A1689) non-parametrically, combining strongly lensed images and weak
distortions from wider field Subaru imaging, and we incorporate member galaxies
to improve the lens solution. Strongly lensed galaxies are often locally
affected by member galaxies, however, these perturbations cannot be recovered
in grid based reconstructions because the lensing information is too sparse to
resolve member galaxies. By adding luminosity-scaled member galaxy deflections
to our smooth grid we can derive meaningful solutions with sufficient accuracy
to permit the identification of our own strongly lensed images, so our model
becomes self consistent. We identify 11 new multiply lensed system candidates
and clarify previously ambiguous cases, in the deepest optical and NIR data to
date from Hubble and Subaru. Our improved spatial resolution brings up new
features not seen when the weak and strong lensing effects are used separately,
including clumps and filamentary dark matter around the main halo. Our
treatment means we can obtain an objective mass ratio between the cluster and
galaxy components, for examining the extent of tidal stripping of the luminous
member galaxies. We find a typical mass-to-light ratios of M/L_B = 21 inside
the r<1 arcminute region that drops to M/L_B = 17 inside the r<40 arcsecond
region. Our model independence means we can objectively evaluate the
competitiveness of stacking cluster lenses for defining the geometric
lensing-distance-redshift relation in a model independent way.Comment: 23 pages with 25 figures Replced with MNRAS submitted version. Some
figures have been corrected and minor text edit
The Surprisingly Steep Mass Profile of Abell 1689, from a Lensing Analysis of Subaru Images
Subaru observations of A1689 (z=0.183) are used to derive an accurate,
model-independent mass profile for the entire cluster, r<2 Mpc/h, by combining
magnification bias and distortion measurements. The projected mass profile
steepens quickly with increasing radius, falling away to zero at r~1.0 Mpc/h,
well short of the anticipated virial radius. Our profile accurately matches
onto the inner profile, r<200 kpc/h, derived from deep HST/ACS images. The
combined ACS and Subaru information is well fitted by an NFW profile with
virial mass, (1.93 \pm 0.20)10^15 M_sun, and surprisingly high concentration,
c_vir=13.7^{+1.4}_{-1.1}, significantly larger than theoretically expected
(c_vir~4), corresponding to a relatively steep overall profile. A slightly
better fit is achieved with a steep power-law model that has its 2D logarithmic
slope -3 and core radius theta_c~1.7' (r_c~210 kpc/h), whereas an isothermal
profile is strongly rejected. These results are based on a reliable sample of
background galaxies selected to be redder than the cluster E/S0 sequence. By
including the faint blue galaxy population a much smaller distortion signal is
found, demonstrating that blue cluster members significantly dilute the true
signal for r~400 kpc/h. This contamination is likely to affect most weak
lensing results to date.Comment: 5 pages, 3 figures, to appear in ApJ
Review of a Small-scale Pelagic Longline Fishery off Northeastern Brazil
The annual catches of four small longliners operating off northeast Brazil from 1983 to 1997 were examined across different areas and locations. The total catch comprised tunas (30%), sharks (54%), billfishes (12%), and other fish species (4%). Fishing strategy and annual composition of catches showed large spatial and temporal variabilities with the dominant catches alternating among yellowfin tuna,
Thunnus albacares; gray sharks, Carcharhinus spp.; and blue shark, Prionace glauca. Catches of blue and gray sharks
showed a significant interaction among seamounts, with gray sharks occurring in maximum abundance around those seamounts
that had relatively deep summits and low-sloping depth profiles. Results are discussed in terms of the various factors that may have influenced distribution of effort
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