3,345 research outputs found
The Sunyaev Zel'dovich effect: simulation and observation
The Sunyaev Zel'dovich effect (SZ effect) is a complete probe of ionized
baryons, the majority of which are likely hiding in the intergalactic medium.
We ran a CDM simulation using a moving mesh hydro code to
compute the statistics of the thermal and kinetic SZ effect such as the power
spectra and measures of non-Gaussianity. The thermal SZ power spectrum has a
very broad peak at multipole with temperature fluctuations
K. The power spectrum is consistent with available
observations and suggests a high and a possible role of
non-gravitational heating. The non-Gaussianity is significant and increases the
cosmic variance of the power spectrum by a factor of for .
We explore optimal driftscan survey strategies for the AMIBA CMB
interferometer and their dependence on cosmology. For SZ power spectrum
estimation, we find that the optimal sky coverage for a 1000 hours of
integration time is several hundred square degrees. One achieves an accuracy
better than 40% in the SZ measurement of power spectrum and an accuracy better
than 20% in the cross correlation with Sloan galaxies for . For
cluster searches, the optimal scan rate is around 280 hours per square degree
with a cluster detection rate 1 every 7 hours, allowing for a false positive
rate of 20% and better than 30% accuracy in the cluster SZ distribution
function measurement.Comment: 34 pages, 20 figures. Submitted to ApJ. Simulation maps have been
replaced by high resolution images. For higher resolution color images,
please download from http://www.cita.utoronto.ca/~zhangpj/research/SZ/ We
corrected a bug in our analysis. the SZ power spectrum decreases 50% and y
parameter decrease 25
The anatomy of exhumed river-channel belts: Bedform to beltâscale river kinematics of the Ruby Ranch Member, Cretaceous Cedar Mountain Formation, Utah, USA
Many published interpretations of ancient fluvial systems have relied on observations of extensive outcrops of thick successions. This paper, in contrast, demonstrates that a regional understanding of palaeoriver kinematics, depositional setting and sedimentation rates can be interpreted from local sedimentological measurements of bedform and barform strata. Dune and bar strata, channel planform geometry and bed topography are measured within exhumed fluvial strata exposed as ridges in the Ruby Ranch Member of the Cretaceous Cedar Mountain Formation, Utah, USA. The ridges are composed of lithified stacked channel belts, representing at least five or six reâoccupations of a singleâstrand channel. Lateral sections reveal wellâpreserved barforms constructed of subaqueous dune crossâsets. The topography of palaeobarforms is preserved along the top surface of the outcrops. Comparisons of the channelâbelt centreline to local palaeotransport directions indicate that channel planform geometry was preserved through the reâoccupations, rather than being obscured by lateral migration. Rapid avulsions preserved the state of the active channel bed and its individual bars at the time of abandonment. Inferred minimum sedimentation durations for the preserved elements, inferred from crossâset thickness distributions and assumed bedform migration rates, vary within a belt from one to ten days. Using only these local sedimentological measurements, the depositional setting is interpreted as a fluvial megafan, given the similarity in river kinematics. This paper provides a systematic methodology for the future synthesis of vertical and planview data, including the droneâequipped 2020 Mars Rover mission, to exhumed fluvial and deltaic strata
The importance of detritus and microenvironment nutrient enrichment to the growth of coral reef macroalgae, Halimeda and Dictyota
Some authors have argued net primary production on coral reefs is nutrient limited. However, over the past several decades coral reefs throughout Florida and the Caribbean have undergone a transition from coral to algal dominance, without proportional changes in the nutrient concentrations of surrounding water. Recent research has recognized the importance of benthic nutrient sources for the growth of some coral reef algae and observed the accumulation of dissolved nutrients within algal mats. In this study algae and associated detritus were sampled to investigate and compare the ability of the dominant algae on Florida Keys Reefs, Halimeda opuntia, Dictyota spp. and turf algae, to accumulate detrital material, an important source of dissolved nutrients. Dissolved nutrient concentrations of water occurring within these algae were measured in order to compare the ability of these algae to impede the flux of benthic nutrients to the water column and establish nutrient enriched microenvironments. Finally, growth experiments were conducted to compare the benefits of this localized nutrient enrichment to the growth of two algae with different morphologies, H. tuna and Dictyota spp. Results indicated that all three algal types examined are capable of trapping detrital material. The depleted nitrogen content of this detritus suggested that significant remineralization had occurred. Elevated nutrient concentrations were observed in water collected from within clumps of H. opuntia and Dictyota spp., and suggested the remineralization of detrital material was a source of these dissolved nutrients. In the growth experiments, enrichment of NH4 and NO3, to concentrations observed within these algae, increased the growth rate of Dictyota spp. above that observed in control treatments. A similar treatment effect was not observed in H. tuna. These results suggest that Dictyota spp. was N-limited at ambient nutrient concentrations, and likely benefits from the microenvironment nutrient enrichment observed to occur within this alga. Growth of H. tuna may have been P-limited since concentrations of PO4 were not elevated in enrichment treatments, however is unlikely based on ambient PO4 concentrations. The differences observed here suggest the ability to establish and take advantage of internal, nutrient enriched microenvironments may be related to algal morphology
Effects of Climate Oscillations on Wildland Fire Potential in the Continental United States
The effects of climate oscillations on spatial and temporal variations in wildland fire potential in the continental U.S. are examined from 1979 to 2015 using cyclostationary empirical orthogonal functions (CSEOFs). The CSEOF analysis isolates effects associated with the modulated annual cycle and the El Nino-Southern Oscillation (ENSO). The results show that, in early summer, wildland fire potential is reduced in the southwest during El Nino but is increased in the northwest, with opposite trends for La Nina. In late summer, El Nino is associated with increased wildland fire potential in the southwest. Relative to the mean, the largest impacts of ENSO are observed in the northwest and southeast. Climate impacts on fire potential due to ENSO are found to be most closely associated with variations in relative humidity. The connections established here between fire potential and climate oscillations could result in improved wildland fire risk assessment and resource allocation
The PHASES Differential Astrometry Data Archive. III. Limits to Tertiary Companions
The Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES)
monitored 51 subarcsecond binary systems to evaluate whether tertiary
companions as small as Jovian planets orbited either the primary or secondary
stars, perturbing their otherwise smooth Keplerian motions. Twenty-one of those
systems were observed 10 or more times and show no evidence of additional
companions. A new algorithm is presented for identifying astrometric companions
and establishing the (companion mass)-(orbital period) combinations that can be
excluded from existence with high confidence based on the PHASES observations,
and the regions of mass-period phase space being excluded are presented for 21
PHASES binaries.Comment: 16 pages, Accepted to A
Modernizing State Public Health Enabling Statutes to Reflect the Mission and Essential Services of Public Health
It is unclear whether efforts of the past decade to modernize state public health statutes have succeeded in codifying into state law the currently understood mission and essential services of public health. Although many state health agencies may be operating in a manner consistent with these principles, their codification in state law is crucial for the sustainability of agency efforts in disease prevention and health promotion. This research examines the 50 state public health enabling statutes for their correspondence with the 6 mission statements and the 10 essential services of public health described in Public Health in America. This analysis finds that modernization efforts have not been universally effective in ensuring that the legislative basis of public health is commensurate with the accepted scope of authority necessary to support health agency performance. Given current imperatives for law modernization in public health, this analysis highlights the importance of model statutory language in facilitating the codification of the mission and essential services of public health in state law. As a result, this research provides the practice community with a research base to facilitate statutory reform and develops a framework for future scholarship on the role of law as a determinant of the publicâs health
The PHASES Differential Astrometry Data Archive. V. Candidate Substellar Companions to Binary Systems
The Palomar High-precision Astrometric Search for Exoplanet Systems monitored
51 subarcsecond binary systems to evaluate whether tertiary companions as small
as Jovian planets orbited either the primary or secondary stars, perturbing
their otherwise smooth Keplerian motions. Six binaries are presented that show
evidence of substellar companions orbiting either the primary or secondary
star. Of these six systems, the likelihoods of two of the detected
perturbations to represent real objects are considered to be "high confidence",
while the remaining four systems are less certain and will require continued
observations for confirmation.Comment: 16 Pages, Accepted to A
Multiple opsins in a reef-building coral, Acropora millepora
Opsins, light-sensitive G protein-coupled receptors, have been identified in corals but their properties are largely unknown. Here, we identified six opsin genes (acropsins 1â6) from a coral species Acropora millepora, including three novel opsins (acropsins 4â6), and successfully characterized the properties of four out of the six acropsins. Acropsins 1 and 6 exhibited light-dependent cAMP increases in cultured cells, suggesting that the acropsins could light-dependently activate Gs-type G protein like the box jellyfish opsin from the same opsin group. Spectral sensitivity curves having the maximum sensitivities atâ~â472 nm andâ~â476 nm were estimated for acropsins 1 and 6, respectively, based on the light wavelength-dependent cAMP increases in these opsins-expressing cells (heterologous action spectroscopy). Acropsin 2 belonging to the same group as acropsins 1 and 6 did not induce light-dependent cAMP or Ca2+ changes. We then successfully estimated the acropsin 2 spectral sensitivity curve having its maximum value atâ~â471 nm with its chimera mutant which possessed the third cytoplasmic loop of the Gs-coupled jellyfish opsin. Acropsin 4 categorized as another group light-dependently induced intracellular Ca2+ increases but not cAMP changes. Our results uncovered that the Acropora coral possesses multiple opsins coupling two distinct cascades, cyclic nucleotide and Ca2+signaling light-dependently
CMS Search Plans and Sensitivity to New Physics using Dijets
CMS will use dijets to search for physics beyond the standard model during early LHC running. The inclusive jet cross section as a function of jet transverse momentum, with 10 pb of integrated luminosity, is sensitive to contact interactions beyond the reach of the Tevatron. The dijet mass distribution will be used to search for dijet resonances coming from new particles, for example an excited quark. Additional sensitivity to the existence of contact interactions or dijet resonances can be obtained by comparing dijet rates in two distinct pseudorapidity regions
The X-ray emission from Nova V382 Velorum: I. The hard component observed with BeppoSAX
We present BeppoSAX observations of Nova Velorum 1999 (V382 Vel), done in a
broad X-ray band covering 0.1-300 keV only 15 days after the discovery and
again after 6 months. The nova was detected at day 15 with the BeppoSAX
instruments in the energy range 1.8-10 keV and we attribute the emission to
shocks in the ejecta. The plasma temperature was kT~6 keV and the unabsorbed
flux was F(x)~4.3 x 10(-11) erg/cm**2/s. The nebular material was affected by
high intrinsic absorption of the ejecta. 6 months after after the outburst, the
intrinsic absorption did not play a role, the nova had turned into a bright
supersoft source, and the hot nebular component previously detected had cooled
to a plasma temperature kT<=1 keV. No emission was detected in either
observation above 20 keV.Comment: 1 tex file, 2 figures as .ps, and 1 .sty file of MNRA
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