7,378 research outputs found
Perspectives on subnational carbon and climate footprints: A case study of Southampton, UK
Sub-national governments are increasingly interested in local-level climate change management. Carbon- (CO2 and CH4) and climate-footprints—(Kyoto Basket GHGs) (effectively single impact category LCA metrics, for global warming potential) provide an opportunity to develop models to facilitate effective mitigation. Three approaches are available for the footprinting of sub-national communities. Territorial-based approaches, which focus on production emissions within the geo-political boundaries, are useful for highlighting local emission sources but do not reflect the transboundary nature of sub-national community infrastructures. Transboundary approaches, which extend territorial footprints through the inclusion of key cross boundary flows of materials and energy, are more representative of community structures and processes but there are concerns regarding comparability between studies. The third option, consumption-based, considers global GHG emissions that result from final consumption (households, governments, and investment). Using a case study of Southampton, UK, this chapter develops the data and methods required for a sub-national territorial, transboundary, and consumption-based carbon and climate footprints. The results and implication of each footprinting perspective are discussed in the context of emerging international standards. The study clearly shows that the carbon footprint (CO2 and CH4 only) offers a low-cost, low-data, universal metric of anthropogenic GHG emission and subsequent management
A VLA Survey For Faint Compact Radio Sources in the Orion Nebula Cluster
We present Karl G. Janksy Very Large Array (VLA) 1.3 cm, 3.6 cm, and 6 cm
continuum maps of compact radio sources in the Orion Nebular Cluster. We
mosaicked 34 square arcminutes at 1.3 cm, 70 square arcminutes at 3.6 cm and
109 square arcminutes at 6 cm, containing 778 near-infrared detected YSOs and
190 HST-identified proplyds (with significant overlap between those
characterizations). We detected radio emission from 175 compact radio sources
in the ONC, including 26 sources that were detected for the first time at these
wavelengths. For each detected source we fit a simple free-free and dust
emission model to characterize the radio emission. We extrapolate the free-free
emission spectrum model for each source to ALMA bands to illustrate how these
measurements could be used to correctly measure protoplanetary disk dust masses
from sub-millimeter flux measurements. Finally, we compare the fluxes measured
in this survey with previously measured fluxes for our targets, as well as four
separate epochs of 1.3 cm data, to search for and quantify variability of our
sources.Comment: 13 pages, 6 figures, 4 tables, ApJ, in pres
Comparative Metal Ion Binding to Native and Chemically Modified Datura innoxia Immobilized Biomaterials
SDSS J142625.71+575218.3: A Prototype for A New Class of Variable White Dwarf
We present the results of a search for pulsations in six of the recently discovered carbon-atmosphere white dwarf ("hot DQ") stars. On the basis of our theoretical calculations, the star SDSS J142625.71 + 575218.3 is the only object expected to pulsate. We observe this star to be variable, with significant power at 417.7 s and 208.8 s ( first harmonic), making it a strong candidate as the first member of a new class of pulsating white dwarf stars, the DQVs. Its folded pulse shape, however, is quite different from that of other white dwarf variables and shows similarities with that of the cataclysmic variable AM CVn, raising the possibility that this star may be a carbon-transferring analog of AM CVn stars. In either case, these observations represent the discovery of a new and exciting class of object.NSF AST-0507639, AST-0602288, AST-0607480, AST-0307321Astronom
The FLIC Overlap Quark Propagator
FLIC overlap fermions are a variant of the standard (Wilson) overlap action,
with the FLIC (Fat Link Irrelevant Clover) action as the overlap kernel rather
than the Wilson action. The structure of the FLIC overlap fermion propagator in
momentum space is studied, and a comparison against previous studies of the
Wilson overlap propagator in quenched QCD is performed. To explore the scaling
properties of the propagator for the two actions, numerical calculations are
performed in Landau Gauge across three lattices with different lattice spacing
and similar physical volumes. We find that at light quark masses the acti
ons agree in both the infrared and the ultraviolet, but at heavier masses some
disagreement in the ultraviolet appears. This is attributed to the two action s
having different discretisation errors with the FLIC overlap providing superior
performance in this regime. Both actions scale reasonably, but some scaling
violations are observed
Gluons, quarks, and the transition from nonperturbative to perturbative QCD
Lattice-based investigations of two fundamental QCD quantities are described,
namely the gluon and quark propagators in Landau gauge. We have studied the
Landau gauge gluon propagator using a variety of lattices with spacings from a
= 0.17 to 0.41 fm. We demonstrate that it is possible to obtain scaling
behavior over a very wide range of momenta and lattice spacings and to explore
the infinite volume and continuum limits. These results confirm that the Landau
gauge gluon propagator is infrared finite. We study the Landau gauge quark
propagator in quenched QCD using two forms of the O(a)-improved propagator and
we find good agreement between these. The extracted value of the infrared quark
mass in the chiral limit is found to be 300 +/- 30 MeV. We conclude that the
momentum regime where the transition from nonperturbative to perturbative QCD
occurs is Q^2 approx 4GeV^2.Comment: 8 pages, 6 figures, 1 table. Talk presented by AGW at the Workshop on
Lepton Scattering, Hadrons and QCD, March 26-April 5, 2001, CSSM, Adelaide,
Australia. To appear in the proceeding
Scaling behavior of quark propagator in full QCD
We study the scaling behavior of the quark propagator on two lattices with
similar physical volume in Landau gauge with 2+1 flavors of dynamical quarks in
order to test whether we are close to the continuum limit for these lattices.
We use configurations generated with an improved staggered (``Asqtad'') action
by the MILC collaboration. The calculations are performed on
lattices with lattice spacing fm and on lattices
with lattice spacing fm. We calculate the quark mass function,
, and the wave-function renormalization function, , for a
variety of bare quark masses. Comparing the behavior of these functions on the
two sets of lattices we find that both and show little
sensitivity to the ultraviolet cutoff.Comment: 6 pages, 5 figure
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