7,202 research outputs found
Supernova Constraints and Systematic Uncertainties from the First Three Years of the Supernova Legacy Survey
We combine high-redshift Type Ia supernovae from the first three years of the Supernova Legacy Survey (SNLS) with other supernova (SN) samples, primarily at lower redshifts, to form a high-quality joint sample of 472 SNe (123 low-z, 93 SDSS, 242 SNLS, and 14 Hubble Space Telescope). SN data alone require cosmic acceleration at >99.999% confidence, including systematic effects. For the dark energy equation of state parameter (assumed constant out to at least z = 1.4) in a flat universe, we find w = –0.91^(+0.16)_(–0.20)(stat)^(+0.07)_(–0.14)(sys) from SNe only, consistent with a cosmological constant. Our fits include a correction for the recently discovered relationship between host-galaxy mass and SN absolute brightness. We pay particular attention to systematic uncertainties, characterizing them using a systematic covariance matrix that incorporates the redshift dependence of these effects, as well as the shape-luminosity and color-luminosity relationships. Unlike previous work, we include the effects of systematic terms on the empirical light-curve models. The total systematic uncertainty is dominated by calibration terms. We describe how the systematic uncertainties can be reduced with soon to be available improved nearby and intermediate-redshift samples, particularly those calibrated onto USNO/SDSS-like systems
Vector unparticle contributions to lepton g-2
The generic unparticle propagator may be modified in two ways. Breaking the
conformal symmetry effectively adds a mass term to the propagator, while
considering vacuum polarization corrections adds a width-like term. Both of
these modifications result naturally from the coupling of the unparticle to
standard model (SM) fields. We explore how these modifications to the
propagator affect the calculation of the lepton anomalous magnetic moment using
an integral approximation of the propagator that is accurate for
, where is the unparticle dimension. We find that for this
range of and various values of the conformal breaking scale , the
value of calculated when allowing various SM fermions to run in the
unparticle self-energy loops does not significantly deviate from the value of
when the width term is ignored. We also investigate the limits on a
characteristic mass scale for the unparticle sector as a function of and
.Comment: 16 pages, 11 figures, 2 tables. Included neutrinos in loops. Added
reference
Brooks's theorem for measurable colorings
We generalize Brooks's theorem to show that if is a Borel graph on a
standard Borel space of degree bounded by which contains no
-cliques, then admits a -measurable -coloring with respect
to any Borel probability measure on , and a Baire measurable
-coloring with respect to any compatible Polish topology on . The proof
of this theorem uses a new technique for constructing one-ended spanning
subforests of Borel graphs, as well as ideas from the study of list colorings.
We apply the theorem to graphs arising from group actions to obtain factor of
IID -colorings of Cayley graphs of degree , except in two exceptional
cases.Comment: Minor correction
Management of sleep apnea: a critical look at intra‐oral appliances
With so many disciplines of both medicine and dentistry involved in the treatment of obstructive sleep apnea (OSA), several forms of therapy are available. The orthodontist is rarely considered when the diagnosis of chronic obstructive sleep apnea (OSA) is delivered. However, the scope of orthodontic care today is much broader than the mere alignment of teeth. While the current gold standard for OSA care remains continuous positive air pressure (CPAP), the patient may be given a prescription for an intra‐oral sleep appliance. When orthodontists work in concert with their medical colleagues to provide a sleep appliance, several considerations must be made including the evidence regarding oral appliance efficacy. For some patients, oral appliances are highly successful; however, even for responsive patients, there are risks associated with oral appliance therapy. The aim of the paper was to present a critical review of the current level of evidence for the use of oral appliances in the treatment of OSA. A substantial number of publications ranging from case reports, uncontrolled and controlled case series, prospective randomized studies, and even a small number of systematic reviews were available. The existing systematic reviews were based on either a limited number of prospective studies with limited numbers of patients or in some cases were based on subjective data only. As a result, a narrative review of the literature was performed that discusses objective clinically testable criteria and recent developments that may aid future research investigations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111150/1/ocr12071.pd
Methane emissions from the 2015 Aliso Canyon blowout in Los Angeles, CA.
Single-point failures of natural gas infrastructure can hamper methane emission control strategies designed to mitigate climate change. The 23 October 2015 blowout of a well connected to the Aliso Canyon underground storage facility in California resulted in a massive release of natural gas. Analysis of methane and ethane data from dozens of plume transects, collected during 13 research-aircraft flights between 7 November 2015 and 13 February 2016, shows atmospheric leak rates of up to 60 metric tons of methane and 4.5 metric tons of ethane per hour. At its peak, this blowout effectively doubled the methane emission rate of the entire Los Angeles basin and, in total, released 97,100 metric tons of methane to the atmosphere
Measurable realizations of abstract systems of congruences
An abstract system of congruences describes a way of partitioning a space
into finitely many pieces satisfying certain congruence relations. Examples of
abstract systems of congruences include paradoxical decompositions and
-divisibility of actions. We consider the general question of when there are
realizations of abstract systems of congruences satisfying various
measurability constraints. We completely characterize which abstract systems of
congruences can be realized by nonmeager Baire measurable pieces of the sphere
under the action of rotations on the -sphere. This answers a question of
Wagon. We also construct Borel realizations of abstract systems of congruences
for the action of on .
The combinatorial underpinnings of our proof are certain types of decomposition
of Borel graphs into paths. We also use these decompositions to obtain some
results about measurable unfriendly colorings.Comment: minor correction
Vesivirus 2117 capsids more closely resemble sapovirus and lagovirus particles than other known vesivirus structures
Vesivirus 2117 is an adventitious agent that in 2009, was identified as a contaminant of CHO cells propagated in bioreactors at a pharmaceutical manufacturing plant belonging to Genzyme. The consequent interruption in supply of Fabrazyme and Cerezyme (drugs used to treat Fabry and Gaucher disease respectively), caused significant economic losses. Vesivirus 2117 is a member of the Caliciviridae; a family of small icosahedral viruses encoding a positive sense RNA genome. We have used cryo-electron microscopy and three dimensional image reconstruction to calculate a structure of vesivirus 2117 virus like particles as well as feline calicivirus and a chimeric sapovirus. We present a structural comparison of several members of the Caliciviridae, showing that the distal P domain of vesivirus 2117 is morphologically distinct from that seen in other known vesivirus structures. Furthermore, at intermediate resolutions we found a high level of structural similarity between vesivirus 2117 and Caliciviridae from other genera, such as sapovirus and rabbit haemorrhagic disease virus. Phylogenetic analysis confirms vesivirus 2117 as a vesivirus closely related to canine vesiviruses. We postulate that morphological differences in virion structure seen between vesivirus clades may reflect differences in receptor usage
Supersymmetry Without Prejudice at the 7 TeV LHC
We investigate the model independent nature of the Supersymmetry search
strategies at the 7 TeV LHC. To this end, we study the
missing-transverse-energy-based searches developed by the ATLAS Collaboration
that were essentially designed for mSUGRA. We simulate the signals for ~71k
models in the 19-dimensional parameter space of the pMSSM. These models have
been found to satisfy existing experimental and theoretical constraints and
provide insight into general features of the MSSM without reference to a
particular SUSY breaking scenario or any other assumptions at the GUT scale.
Using backgrounds generated by ATLAS, we find that imprecise knowledge of these
estimated backgrounds is a limiting factor in the potential discovery of these
models and that some channels become systematics-limited at larger
luminosities. As this systematic error is varied between 20-100%, roughly half
to 90% of this model sample is observable with significance S>5 for 1 fb^{-1}
of integrated luminosity. We then examine the model characteristics for the
cases which cannot be discovered and find several contributing factors. We find
that a blanket statement that squarks and gluinos are excluded with masses
below a specific value cannot be made. We next explore possible modifications
to the kinematic cuts in these analyses that may improve the pMSSM model
coverage. Lastly, we examine the implications of a null search at the 7 TeV LHC
in terms of the degree of fine-tuning that would be present in this model set
and for sparticle production at the 500 GeV and 1 TeV Linear Collider.Comment: 51 pages, 26 figure
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