630 research outputs found
Gaia14aae: the first fully-eclipsing AM CVn
AM CVns are a class of cataclysmic variables consisting of a white dwarf accreting H-deficient matter from a donor star. With periods of 5 to 65 minutes, AM CVns include the shortest period binaries containing white dwarfs. AM CVns are believed to form by one of three formation channels which can in principle be distinguished by the nature of the donor star, but are difficult to constrain observationally. Gaia14aae was one of the first transients discovered by the Gaia Science Alerts project. It eclipses on a period of 50 minutes, and is the only known AM CVn in which the white dwarf is fully eclipsed. This makes it an attractive system for parameter studies. We present an update on our attempts to measure these properties, using high-speed multi-colour photometry. Preliminary results suggest that the donor star is not as degenerate as predicted by models of white dwarf donors
Setting the agenda: Climate change adaptation and mitigation for food systems in the developing world
New agricultural development pathways are required to meet climate change adaptation and mitigation needs in the food systems of low-income countries. A research and policy agenda is provided to indicate where innovation and new knowledge are needed. Adaptation requires identifying suitable crop varieties and livestock breeds, as well as building resilient farming and natural resources systems, institutions for famine and crop failure relief, and mechanisms for rapid learning by farmers. Mitigation requires transitioning to âlow climate impactâ agriculture that reduces emissions while achieving food security, economic well-being and sustainability. Efficient interventions, incentives for large-scale shifts in practices, and monitoring systems are required. Integrated assessments of adaptation and mitigation are needed to better understand the synergies and trade-offs among outcomes
Wellbeing agencies in the High Street: the rebirth of primary health care?
This scoping review combines a secondary data analysis of global exemplars with case studies of increasingly diverse wellbeing agencies in highly âliveableâ Winchester and Melbourne. It identifies a research agenda, which includes the roles of social and commercial enterprises and their needs for effective community governance
Field testing for toxic algae with a microarray: initial results from the MIDTAL project
One of the key tasks in MIDTAL (MIcroarrays for the Detection of Toxic ALgae) is to demonstrate
the applicability of microarrays to monitor harmful algae across a broad range of ecological niches
and toxic species responsible for harmful algal events. Water samples are collected from a series of
sites used in national phytoplankton and biotoxin monitoring across Europe. The samples are filtered;
rRNA is extracted, labelled with a fluorescent dye and applied to a microarray chip. The signal
intensity from >120 probes previously spotted on the chip is measured and analysed. Preliminary
results comparing microarray signal intensities with actual field counts are presented.VersiĂłn del edito
D* Production in Deep Inelastic Scattering at HERA
This paper presents measurements of D^{*\pm} production in deep inelastic
scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The
data have been taken with the ZEUS detector at HERA. The decay channel
(+ c.c.) has been used in the study. The
cross section for inclusive D^{*\pm} production with
and is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region
{ GeV and }. Differential cross
sections as functions of p_T(D^{*\pm}), and are
compared with next-to-leading order QCD calculations based on the photon-gluon
fusion production mechanism. After an extrapolation of the cross section to the
full kinematic region in p_T(D^{*\pm}) and (D^{*\pm}), the charm
contribution to the proton structure function is
determined for Bjorken between 2 10 and 5 10.Comment: 17 pages including 4 figure
Observation of Scaling Violations in Scaled Momentum Distributions at HERA
Charged particle production has been measured in deep inelastic scattering
(DIS) events over a large range of and using the ZEUS detector. The
evolution of the scaled momentum, , with in the range 10 to 1280
, has been investigated in the current fragmentation region of the Breit
frame. The results show clear evidence, in a single experiment, for scaling
violations in scaled momenta as a function of .Comment: 21 pages including 4 figures, to be published in Physics Letters B.
Two references adde
Observation of hard scattering in photoproduction events with a large rapidity gap at HERA
Events with a large rapidity gap and total transverse energy greater than 5
GeV have been observed in quasi-real photoproduction at HERA with the ZEUS
detector. The distribution of these events as a function of the
centre of mass energy is consistent with diffractive scattering. For total
transverse energies above 12 GeV, the hadronic final states show predominantly
a two-jet structure with each jet having a transverse energy greater than 4
GeV. For the two-jet events, little energy flow is found outside the jets. This
observation is consistent with the hard scattering of a quasi-real photon with
a colourless object in the proton.Comment: 19 pages, latex, 4 figures appended as uuencoded fil
New fossil remains of Homo naledi from the Lesedi Chamber, South Africa
The Rising Star cave system has produced abundant fossil hominin remains within the
Dinaledi Chamber, representing a minimum of 15 individuals attributed to Homo naledi. Further
exploration led to the discovery of hominin material, now comprising 131 hominin specimens,
within a second chamber, the Lesedi Chamber. The Lesedi Chamber is far separated from the
Dinaledi Chamber within the Rising Star cave system, and represents a second depositional context
for hominin remains. In each of three collection areas within the Lesedi Chamber, diagnostic
skeletal material allows a clear attribution to H. naledi. Both adult and immature material is present.
The hominin remains represent at least three individuals based upon duplication of elements, but
more individuals are likely present based upon the spatial context. The most significant specimen is
the near-complete cranium of a large individual, designated LES1, with an endocranial volume of
approximately 610 ml and associated postcranial remains. The Lesedi Chamber skeletal sample
extends our knowledge of the morphology and variation of H. naledi, and evidence of H. naledi
from both recovery localities shows a consistent pattern of differentiation from other hominin
species.SP201
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
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