1,646 research outputs found
Feral pig management in Australia: implications for disease control
Feral pigs (Sus scrofa) were introduced to Australia following European settlement and are now widely distributed in a variety of habitats. High-density populations are found particularly in north-eastern Australia. Feral pigs are commonly viewed as a valued hunting or commercial resource, occasionally as an important cultural resource, but overwhelmingly as a devastating agricultural and environmental pest. Their wide-ranging impacts demand intervention through control programs on many production and conservation lands. Feral pigs also carry pathogens of human health significance and contribute to the persistence and transmission of a range of endemic diseases or pathogens of livestock and wildlife. Feral pigs are the invasive species of most concern in Australia as potential vectors of exotic diseas
The Magnetic Distortion Calibration System of the LHCb RICH1 Detector
The LHCb RICH1 detector uses hybrid photon detectors (HPDs) as its optical
sensors. A calibration system has been constructed to provide corrections for
distortions that are primarily due to external magnetic fields. We describe
here the system design, construction, operation and performance.Comment: 9 pages, 14 figure
Sub-m s upper limits from a deep HARPS-N radial-velocity search for planets orbiting HD 166620 and HD 144579
Minimising the impact of stellar variability in Radial Velocity (RV)
measurements is a critical challenge in achieving the 10 cm s precision
needed to hunt for Earth twins. Since 2012, a dedicated programme has been
underway with HARPS-N, to conduct a blind RV Rocky Planets Search (RPS) around
bright stars in the Northern Hemisphere. Here we describe the results of a
comprehensive search for planetary systems in two RPS targets, HD 166620 and HD
144579. Using wavelength-domain line-profile decorrelation vectors to mitigate
the stellar activity and performing a deep search for planetary reflex motions
using a trans-dimensional nested sampler, we found no significant planetary
signals in the data sets of either of the stars. We validated the results via
data-splitting and injection recovery tests. Additionally, we obtained the 95th
percentile detection limits on the HARPS-N RVs. We found that the likelihood of
finding a low-mass planet increases noticeably across a wide period range when
the inherent stellar variability is corrected for using scalpels U-vectors. We
are able to detect planet signals with M for orbital
periods shorter than 10 days. We demonstrate that with our decorrelation
technique, we are able to detect signals as low as 54 cm s, which brings
us closer to the calibration limit of 50 cm s demonstrated by HARPS-N.
Therefore, we show that we can push down towards the RV precision required to
find Earth analogues using high-precision radial velocity data with novel
data-analysis techniques.Comment: 7 tables, 24 figures (including those in appendix
Rotational velocities of low-mass stars in the Pleiades and Hyades
We have obtained high-resolution spectra of 89 M dwarf members of the
Pleiades and Hyades and have derived radial velocities, H-alpha equivalent
widths, and spectroscopic rotational velocities for these stars. Typical masses
of the newly-observed Pleiades and Hyades stars are ~ 0.4 M_{\sun} and ~ 0.2
M_{\sun}, respectively. We combine our new observations with previously
published data to explore the rotational evolution of young stars with M < 0.4
M_\sun. The average rotation rate in the Hyades (age 600 Myr) is about 0.4 that
of the Pleiades (110 Myr), and the mean equivalent widths of H-alpha are also
lower. As found in previous studies, the correlation between rotation and
chromospheric activity is identical in both clusters, implying that the lower
activity in the Hyades is a result of the lower rotation rates. We show that a
simple scaling of the Pleiades rotational distribution for M \leq 0.4 M_{\sun},
corrected for the effects of structural evolution, matches that of the Hyades
if the average angular momentum loss from the Pleiades to the Hyades age is
factor of \approx 6. This suggests that the distribution of initial angular
momenta and disk-locking lifetimes for the lowest mass stars was similar in
both clusters. We argue that this result provides further evidence for a
saturation of the angular momentum loss rate at high rotational velocities.Comment: 22 pages, 11 figures, accepted for publication in The Astronomical
Journal, tentatively scheduled for March 200
Discovery of a z=4.93, X-ray selected quasar by the Chandra Multiwavelength Project (ChamP)
We present X-ray and optical observations of CXOMP J213945.0-234655, a high
redshift (z=4.93) quasar discovered through the Chandra Multiwavelength Project
(ChaMP). This object is the most distant X-ray selected quasar published, with
an X-ray luminosity of L(X)=5.9x10^44 erg/s (measured in the 0.3-2.5 keV band
and corrected for Galactic absorption). CXOMP J213945.0-234655 is a g' dropout
object (>26.2), with r'=22.87 and i'=21.36. The rest-frame X-ray to optical
flux ratio is similar to quasars at lower redshifts and slightly X-ray bright
relative to z>4 optically-selected quasars observed with Chandra. The ChaMP is
beginning to acquire significant numbers of high redshift quasars to
investigate the unobscured X-ray luminosity function out to z~5.Comment: Published in ApJ Letters; 4 pages; 3 figures;
http://hea-www.harvard.edu/CHAMP
A study of Egyptian and Palestine trans-formal firms – A neglected category operating in the borderland between formality and informality
This article outlines a new approach to firm behaviour different from both ‘dichotomist’ and ‘continuum’ formal/informal models. The approach adopts a new heuristic based on the notion of a borderland as space of interaction between dimensions of formality, and creates an umbrella category of trans-formal firms, which are neither purely formal nor informal. Three formality dimensions are adopted: (i) registration of the firm, (ii) existence of a bank account in the name of the firm, and the (iii) presence of an official balance sheet. After elucidating the new approach theoretically, the paper assesses the analytical capacity of the approach with quantitative and qualitative information representing 16 Egyptian and 16 Palestinian firms. The majority of the considered firms are found to be trans-formal moving in a space of decision-making representing our new, broadened notion of borderland showing that policies aiming at formalization processes misrepresent the realities of significant numbers of firms
Bridging the gaps among research, policy and practice in ten low- and middle-income countries: Development and testing of a questionnaire for researchers
<p>Abstract</p> <p>Background</p> <p>A questionnaire could assist researchers, policymakers, and healthcare providers to describe and monitor changes in efforts to bridge the gaps among research, policy and practice. No questionnaire focused on researchers' engagement in bridging activities related to high-priority topics (or the potential correlates of their engagement) has been developed and tested in a range of low- and middle-income countries (LMICs).</p> <p>Methods</p> <p>Country teams from ten LMICs (China, Ghana, India, Iran, Kazakhstan, Laos, Mexico, Pakistan, Senegal, and Tanzania) participated in the development and testing of a questionnaire. To assess reliability we calculated the internal consistency of items within each of the ten conceptual domains related to bridging activities (specifically Cronbach's alpha). To assess face and content validity we convened several teleconferences and a workshop. To assess construct validity we calculated the correlation between scales and counts (i.e., criterion measures) for the three countries that employed both and we calculated the correlation between different but theoretically related (i.e., convergent) measures for all countries.</p> <p>Results</p> <p>Internal consistency (Cronbach's alpha) for sets of related items was very high, ranging from 0.89 (0.86-0.91) to 0.96 (0.95-0.97), suggesting some item redundancy. Both face and content validity were determined to be high. Assessments of construct validity using criterion-related measures showed statistically significant associations for related measures (with gammas ranging from 0.36 to 0.73). Assessments using convergent measures also showed significant associations (with gammas ranging from 0.30 to 0.50).</p> <p>Conclusions</p> <p>While no direct comparison can be made to a comparable questionnaire, our findings do suggest a number of strengths of the questionnaire but also the need to reduce item redundancy and to test its capacity to monitor changes over time.</p
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