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Monte Carlo Ray Tracing Based Sensitivity Analysis of the Atmospheric and the Ocean Parameters on Top of the Atmosphere Radiance  [PDF]
Kohei Arai
International Journal of Advanced Computer Sciences and Applications , 2013,
Abstract: Monte Carlo Ray Tracing: MCRT based sensitivity analysis of the geophysical parameters (the atmosphere and the ocean) on Top of the Atmosphere: TOA radiance in visible to near infrared wavelength regions is conducted. As the results, it is confirmed that the influence due to the atmosphere is greater than that of the ocean. Scattering and absorption due to aerosol particles and molecules in the atmosphere is major contribution followed by water vapor and ozone while scattering due to suspended solid is dominant contribution for the ocean parameters.
Data-driven Estimations of Z, W and Top Backgrounds  [PDF]
Mark Hodgkinson,for the ATLAS Collaboration
Physics , 2008,
Abstract: The Standard Model processes of W, Z and top quark production in association with jets constitute a major background to searches for Supersymmetry at the LHC. We describe recent work performed in the ATLAS Collaboration to estimate these backgrounds for a basic SUSY selection, and we discuss methods to derive them from the first ATLAS data.
Top Production: Sensitivity to New Physics  [PDF]
Christopher T. Hill,Stephen J. Parke
Physics , 1993, DOI: 10.1103/PhysRevD.49.4454
Abstract: The production cross--section and distributions of the top quark are sensitive to new physics, e.g., the $t\overline{t}$ system can be a probe of new resonances or gauge bosons that are strongly coupled to the top quark, in analogy to Drell--Yan production. The existence of such new physics is expected in dynamical electroweak symmetry breaking schemes, and associated with the large mass of the top quark. The total top production cross--section can be more than doubled, and distributions significantly distorted with a chosen scale of new physics of $\sim 1 $ TeV in the vector color singlet or octet $s$--channel. New resonance physics is most readily discernible in the high--$p_T$ distributions of the single top quark and of the $W$ boson.
Aerosol direct radiative effect at the top of the atmosphere over cloud free ocean derived from four years of MODIS data
L. A. Remer ,Y. J. Kaufman
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2006,
Abstract: A four year record of MODIS spaceborne data provides a new measurement tool to assess the aerosol direct radiative effect at the top of the atmosphere. MODIS derives the aerosol optical thickness and microphysical properties from the scattered sunlight at 0.55–2.1 μm. The monthly MODIS data used here are accumulated measurements across a wide range of view and scattering angles and represent the aerosol's spectrally resolved angular properties. We use these data consistently to compute with estimated accuracy of ±0.6 Wm 2 the reflected sunlight by the aerosol over global oceans in cloud free conditions. The MODIS high spatial resolution (0.5 km) allows observation of the aerosol impact between clouds that can be missed by other sensors with larger footprints. We found that over the clear-sky global ocean the aerosol reflected 5.3±0.6 Wm 2 with an average radiative efficiency of 49±2 Wm 2 per unit optical thickness. The seasonal and regional distribution of the aerosol radiative effects are discussed. The analysis adds a new measurement perspective to a climate change problem dominated so far by models.
Flux Imbalance Analysis and the Sensitivity of Cellular Growth to Changes in Metabolite Pools  [PDF]
Ed Reznik,Pankaj Mehta,Daniel Segrè
PLOS Computational Biology , 2013, DOI: 10.1371/journal.pcbi.1003195
Abstract: Stoichiometric models of metabolism, such as flux balance analysis (FBA), are classically applied to predicting steady state rates - or fluxes - of metabolic reactions in genome-scale metabolic networks. Here we revisit the central assumption of FBA, i.e. that intracellular metabolites are at steady state, and show that deviations from flux balance (i.e. flux imbalances) are informative of some features of in vivo metabolite concentrations. Mathematically, the sensitivity of FBA to these flux imbalances is captured by a native feature of linear optimization, the dual problem, and its corresponding variables, known as shadow prices. First, using recently published data on chemostat growth of Saccharomyces cerevisae under different nutrient limitations, we show that shadow prices anticorrelate with experimentally measured degrees of growth limitation of intracellular metabolites. We next hypothesize that metabolites which are limiting for growth (and thus have very negative shadow price) cannot vary dramatically in an uncontrolled way, and must respond rapidly to perturbations. Using a collection of published datasets monitoring the time-dependent metabolomic response of Escherichia coli to carbon and nitrogen perturbations, we test this hypothesis and find that metabolites with negative shadow price indeed show lower temporal variation following a perturbation than metabolites with zero shadow price. Finally, we illustrate the broader applicability of flux imbalance analysis to other constraint-based methods. In particular, we explore the biological significance of shadow prices in a constraint-based method for integrating gene expression data with a stoichiometric model. In this case, shadow prices point to metabolites that should rise or drop in concentration in order to increase consistency between flux predictions and gene expression data. In general, these results suggest that the sensitivity of metabolic optima to violations of the steady state constraints carries biologically significant information on the processes that control intracellular metabolites in the cell.
Top Quark Pair Production: Sensitivity to New Physics  [PDF]
Stephen Parke
Physics , 1995,
Abstract: The production cross--section and distributions of the top quark are sensitive to new physics, e.g., the $t\overline{t}$ system can be a probe of new resonances or gauge bosons that are strongly coupled to the top quark, in analogy to Drell--Yan production. The existence of such new physics is expected in dynamical electroweak symmetry breaking schemes, and associated with the large mass of the top quark. The total top production cross--section can be more than doubled, and distributions significantly distorted with a chosen scale of new physics of $\sim 1 $ TeV in the vector color singlet or octet $s$--channel. New resonance physics is most readily discernible in the high--$p_T$ distributions of the single top quark, of the $W$ boson and the mass distribution of the $t\bar{t}$ pair.
Study of ATLAS sensitivity to FCNC top decays  [PDF]
J. Carvalho,N. Castro,L. Chikovani,T. Djobava,J. Dodd,S. McGrath,A. Onofre,J. Parsons,F. Veloso
Physics , 2007, DOI: 10.1140/epjc/s10052-007-0434-0
Abstract: The ATLAS experiment sensitivity to top quark Flavour Changing Neutral Current (FCNC) decays was studied at LHC using ttbar events. While one of the top quarks is expected to follow the dominant Standard Model decay t->bW, the other decays through a FCNC channel, i.e. t-> Z u(c), t-> gamma u(c) or t-> g u(c). Different types of analyses, applied to each FCNC decay mode, were compared. The FCNC branching ratio sensitivity (assuming a 5sigma signal significance) and 95% confidence level limits on the branching ratios (in the hypothesis of signal absence) were obtained.
Unbiased Estimations of Atmosphere Vortices: The Saturn’s Storm by Cassini VIMS-V as Case Study  [PDF]
Maria L. Moriconi, A. Adriani, E. D’Aversa, G. L. Liberti, G. Filacchione, F. Oliva
Journal of Signal and Information Processing (JSIP) , 2016, DOI: 10.4236/jsip.2016.72009
Abstract: The size determination of dynamical structures from spectral images poses the question where to fix the shape’s boundary. Here, we propose a method, suitable for nearly elliptical shape, based on the fit of a 2D Gaussian to the pixel intensities of the spectral image. This method has been tested on a vortex structure embedded in the wake of the 2010 Saturn’s giant storm. On January 4th 2012, the Visual and Infrared Mapping Spectrometer (VIMS), onboard Cassini, observed a giant vortex in the Saturn’s northern hemisphere. The structure was embedded in the wake storm system detected on December 2010 by Fletcher et al. [1]. Therefore, all the VIMS observations focused on the Saturn’s storm have been analyzed to investigate its morphology and development. VIMS detected the vortex from May 2011up to January 2012. The evolution of shape and size has been determined for the vortex cloud top, visible at 890 nm. The largest size resulted 4000 km about and seemed to shrinks continuously up to January 2012, while the shape varied in the second half of the year. The vortex oscillated in 2 degrees latitude around 37°N planetocentric latitude, and drifted in longitude by ~0.75 deg/day in westward direction.
Vacuum fine tuning and empirical estimations of masses of the top-quark and Higgs boson  [PDF]
A. A. Andrianov,N. V. Romanenko
Physics , 1993,
Abstract: The fine-tuning principles are analyzed in search for predictions of top-quark and Higgs-boson masses. The modification of Veltman condition based on the compensation between fermion and boson vacuum energies within the Standard Model multiplets is proposed. It is supplied with the stability under rescaling and with the requirement of minimum for the physical v. e. v. for the Higgs field (zero anomalous dimension). Their joint solution for top-quark and Higgs-boson couplings exists for the cutoff $\Lambda \approx 2.3 \cdot 10^{13}\,GeV$ that yields the low-energy values $m_t = 151 \pm 4\,GeV; m_H = 195 \pm 7\,GeV$.
Statistical variability of top of atmosphere cloud-free shortwave aerosol radiative effect
T. A. Jones ,S. A. Christopher
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2007,
Abstract: The statistical variability of globally averaged MODIS aerosol optical thickness at 0.55 μm (AOT) and top of atmosphere CERES cloud-free shortwave radiative effect (SWRE) is presented. Statistical variability is defined as the robustness of globally averaged statistics relative to data distribution. At the CERES footprint level, which we label "raw data", both the AOT and SWRE data derived from clear-sky CERES-SSF products show significant deviations from a normal distribution as evidenced by high skewness values. The spatial and temporal distribution of the data is also not uniform, with a greater concentration of data occurring in aerosol heavy-regions. As a result, globally averaged AOT and SWRE are overestimated when derived from raw data alone. To compensate, raw data are gridded into 2×2 degree grid-cells (called "gridded" data) to reduce the effect of spatial non-uniformity. However, the underlying non-normal distribution remains and manifests itself by increasing the uncertainty of grid-cell values. Globally averaged AOT and SWRE derived from a gridded dataset are substantially lower than those derived from raw data alone. The range of globally averaged AOT and SWRE values suggests that up to a 50% statistical variability exists, much of which is directly tied to how the data are manipulated prior to averaging. This variability increases when analyzing aerosol components (e.g. anthropogenic) since component AOT (and SWRE) may not exist at all locations were AOT is present. As a result, regions where a particular component AOT does not exist must either not be included in the global average or have data within these regions set to null values. However, each method produces significantly different results. The results of this work indicate simple mean and standard deviation statistics do not adequately describe global aerosol climate forcing data sets like the one used here. We demonstrate that placing raw observations on to a uniform grid is a necessary step before calculating global statistics. However, this by no means eliminates uncertainty in globally averaged AOT and SWRE values, while adding its own set of assumptions. When reporting any globally averaged statistic, it is important to report corresponding distribution and coverage information, in the form of skewness values, probability density functions, and spatial distribution plots, to help quantify its usefulness and robustness.
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