447 research outputs found
surface interpolation and 3d relatability
Although the role of surface-level processes has been demonstrated, visual interpolation models often emphasize contour relationships. We report two experiments on geometric constraints governing 3D interpolation between surface patches without visible edges. Observers were asked to classify pairs of planar patches specified by random dot disparities and visible through circular apertures (aligned or misaligned) in a frontoparallel occluder. On each trial, surfaces appeared in parallel or converging planes with vertical (in Experiment 1) or horizontal (in Experiment 2) tilt and variable amounts of slant. We expected the classification task to be facilitated when patches were perceived as connected. We found enhanced sensitivity and speed for 3D relatable vs. nonrelatable patches. Here 3D relatability does not involve oriented edges but rather inducing patches' orientations computed from stereoscopic information. Performance was markedly affected by slant anisotropy: both sensitivity and speed were worse for patches with horizontal tilt. We found nearly identical advantages of 3D relatability on performance, suggesting an isotropic unit formation process. Results are interpreted as evidence that inducing slant constrains surface interpolation in the absence of explicit edge information: 3D contour and surface interpolation processes share common geometric constraints as formalized by 3D relatability
fatigue life evaluation of car front halfshaft
Abstract The present paper is the result of the collaboration between the Engineering Department of Messina University and the car company Maserati S.p.A. The aim of this paper is to determine the T-N torsion fatigue curve at R= -1 of the mechanical system "front halfshaft" of an existing car. In particular, experimental fatigue tests were carried out in the laboratories of the Engineering Department of the University of Messina. Torsion fatigue tests of the entire mechanical system were carried out on 15 different front halfshafts. Evaluations of the crack propagation and of failure analysis were made to determine the causes of breakage. In conclusion, the T-N fatigue curve of the mechanical system "front halfshaft" has been obtained
Preparation of amino-substituted indenes and 1,4-dihydronaphthalenes using a one-pot multireaction approach: total synthesis of oxybenzo[c]phenanthridine alkaloids
Allylic trichloroacetimidates bearing a 2-vinyl or 2-allylaryl group have been designed as substrates for a one-pot, two-step multi-bond-forming process leading to the general preparation of aminoindenes and amino-substituted 1,4-dihydronaphthalenes. The synthetic utility of the privileged structures formed from this one-pot process was demonstrated with the total synthesis of four oxybenzo[c]phenanthridine alkaloids, oxychelerythrine, oxysanguinarine, oxynitidine, and oxyavicine. An intramolecular biaryl Heck coupling reaction, catalyzed using the HermannâBeller palladacycle was used to effect the key step during the synthesis of the natural products
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Planck intermediate results: LI. Features in the cosmic microwave background temperature power spectrum and shifts in cosmological parameters
The six parameters of the standard ÎCDM model have best-fit values derived from the Planck temperature power spectrum that are shifted somewhat from the best-fit values derived from WMAP data. These shifts are driven by features in the Planck temperature power spectrum at angular scales that had never before been measured to cosmic-variance level precision. We have investigated these shifts to determine whether they are within the range of expectation and to understand their origin in the data. Taking our parameter set to be the optical depth of the reionized intergalactic medium, the baryon density Ï b , the matter density Ï m , the angular size of the sound horizon the spectral index of the primordial power spectrum, n s , and A s e -2Ï (where A s is the amplitude of the primordial power spectrum), we have examined the change in best-fit values between a WMAP-like large angular-scale data set (with multipole moment 800, or splitting at a different multipole, yields similar results. We examined the 800 power spectrum data and find that the features there that drive these shifts are a set of oscillations across a broad range of angular scales. Although they partly appear similar to the effects of enhanced gravitational lensing, the shifts in ÎCDM parameters that arise in response to these features correspond to model spectrum changes that are predominantly due to non-lensing effects; the only exception is, which, at fixed A s e -2Ï , affects the > 800 temperature power spectrum solely through the associated change in A s and the impact of that on the lensing potential power spectrum. We also ask, "what is it about the power spectrum at < 800 that leads to somewhat different best-fit parameters than come from the full range?" We find that if we discard the data at < 30, where there is a roughly 2Ï downward fluctuation in power relative to the model that best fits the full range, the < 800 best-fit parameters shift significantly towards the < 2500 best-fit parameters. In contrast, including < 30, this previously noted "low-deficit" drives n s up and impacts parameters correlated with n s , such as Ï m and H 0 . As expected, the < 30 data have a much greater impact on the < 800 best fit than on the < 2500 best fit. So although the shifts are not very significant, we find that they can be understood through the combined effects of an oscillatory-like set of high-residuals and the deficit in low-power, excursions consistent with sample variance that happen to map onto changes in cosmological parameters. Finally, we examine agreement between PlanckTT data and two other CMB data sets, namely the Planck lensing reconstruction and the TT power spectrum measured by the South Pole Telescope, again finding a lack of convincing evidence of any significant deviations in parameters, suggesting that current CMB data sets give an internally consistent picture of the ÎCDM model
Planck intermediate results : LVII. Joint Planck LFI and HFI data processing
We present the NPIPE processing pipeline, which produces calibrated frequency maps in temperature and polarization from data from the Planck Low Frequency Instrument (LFI) and High Frequency Instrument (HFI) using high-performance computers. NPIPE represents a natural evolution of previous Planck analysis efforts, and combines some of the most powerful features of the separate LFI and HFI analysis pipelines. For example, following the LFI 2018 processing procedure, NPIPE uses foreground polarization priors during the calibration stage in order to break scanning-induced degeneracies. Similarly, NPIPE employs the HFI 2018 time-domain processing methodology to correct for bandpass mismatch at all frequencies. In addition, NPIPE introduces several improvements, including, but not limited to: inclusion of the 8% of data collected during repointing manoeuvres; smoothing of the LFI reference load data streams; in-flight estimation of detector polarization parameters; and construction of maximally independent detector-set split maps. For component-separation purposes, important improvements include: maps that retain the CMB Solar dipole, allowing for high-precision relative calibration in higher-level analyses; well-defined single-detector maps, allowing for robust CO extraction; and HFI temperature maps between 217 and 857 GHz that are binned into 0 ' .9 pixels (N-side = 4096), ensuring that the full angular information in the data is represented in the maps even at the highest Planck resolutions. The net effect of these improvements is lower levels of noise and systematics in both frequency and component maps at essentially all angular scales, as well as notably improved internal consistency between the various frequency channels. Based on the NPIPE maps, we present the first estimate of the Solar dipole determined through component separation across all nine Planck frequencies. The amplitude is (3366.6 +/- 2.7) mu K, consistent with, albeit slightly higher than, earlier estimates. From the large-scale polarization data, we derive an updated estimate of the optical depth of reionization of tau =0.051 +/- 0.006, which appears robust with respect to data and sky cuts. There are 600 complete signal, noise and systematics simulations of the full-frequency and detector-set maps. As a Planck first, these simulations include full time-domain processing of the beam-convolved CMB anisotropies. The release of NPIPE maps and simulations is accompanied with a complete suite of raw and processed time-ordered data and the software, scripts, auxiliary data, and parameter files needed to improve further on the analysis and to run matching simulations.Peer reviewe
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The Simons Observatory: Science goals and forecasts
The Simons Observatory (SO) is a new cosmic microwave background experiment
being built on Cerro Toco in Chile, due to begin observations in the early
2020s. We describe the scientific goals of the experiment, motivate the design,
and forecast its performance. SO will measure the temperature and polarization
anisotropy of the cosmic microwave background in six frequency bands: 27, 39,
93, 145, 225 and 280 GHz. The initial configuration of SO will have three
small-aperture 0.5-m telescopes (SATs) and one large-aperture 6-m telescope
(LAT), with a total of 60,000 cryogenic bolometers. Our key science goals are
to characterize the primordial perturbations, measure the number of
relativistic species and the mass of neutrinos, test for deviations from a
cosmological constant, improve our understanding of galaxy evolution, and
constrain the duration of reionization. The SATs will target the largest
angular scales observable from Chile, mapping ~10% of the sky to a white noise
level of 2 K-arcmin in combined 93 and 145 GHz bands, to measure the
primordial tensor-to-scalar ratio, , at a target level of .
The LAT will map ~40% of the sky at arcminute angular resolution to an expected
white noise level of 6 K-arcmin in combined 93 and 145 GHz bands,
overlapping with the majority of the LSST sky region and partially with DESI.
With up to an order of magnitude lower polarization noise than maps from the
Planck satellite, the high-resolution sky maps will constrain cosmological
parameters derived from the damping tail, gravitational lensing of the
microwave background, the primordial bispectrum, and the thermal and kinematic
Sunyaev-Zel'dovich effects, and will aid in delensing the large-angle
polarization signal to measure the tensor-to-scalar ratio. The survey will also
provide a legacy catalog of 16,000 galaxy clusters and more than 20,000
extragalactic sources
PKQuest: a general physiologically based pharmacokinetic model. Introduction and application to propranolol
BACKGROUND: A "physiologically based pharmacokinetic" (PBPK) approach uses a realistic model of the animal to describe the pharmacokinetics. Previous PBPKs have been designed for specific solutes, required specification of a large number of parameters and have not been designed for general use. METHODS: This new PBPK program (PKQuest) includes a "Standardhuman" and "Standardrat" data set so that the user input is minimized. It has a simple user interface, graphical output and many new features: 1) An option that uses the measured plasma concentrations to solve for the time course of the gastrointestinal, intramuscular, intraperotineal or skin absorption and systemic availability of a drug â for a general non-linear system. 2) Capillary permeability limitation defined in terms of the permeability-surface area products. 4) Saturable plasma and tissue protein binding. 5) A lung model that includes perfusion-ventilation mismatch. 6) A general optimization routine using either a global (simulated annealing) or local (Powell) minimization applicable to all model parameters. RESULTS: PKQuest was applied to measurements of human propranolol pharmacokinetics and intestinal absorption. A meal has two effects: 1) increases portal blood flow by 50%; and 2) decreases liver metabolism by 20%. There is a significant delay in the oval propranolol absorption in fasting subjects that is absent in fed subjects. The oral absorption of the long acting form of propranolol continues for a period of more than 24 hours. CONCLUSIONS: PKQuest provides a new general purpose, easy to use, freely distributed and physiologically rigorous PBPK software routine
Planck 2018 results. VIII. Gravitational lensing
We present measurements of the cosmic microwave background (CMB) lensing potential using the final Planck 2018 temperature and polarization data. We increase the significance of the detection of lensing in the polarization maps from 5Ï to 9Ï. Combined with temperature, lensing is detected at 40Ï4. We present an extensive set of tests of the robustness of the lensing-potential power spectrum, and construct a minimum-variance estimator likelihood over lensing multipoles 8â€Lâ€400. We find good consistency between lensing constraints and the results from the Planck CMB power spectra within the ÎCDMÎCDM model. Combined with baryon density and other weak priors, the lensing analysis alone constrains Ï8Ω0.25m=0.589±0.020 (1Ï errors). Also combining with baryon acoustic oscillation (BAO) data, we find tight individual parameter constraints, Ï8=0.811±0.019, H0=67.9+1.2â1.3kmsâ1Mpcâ1, and Ωm=0.303+0.016â0.018. Combining with Planck CMB power spectrum data, we measure Ï8 to better than 1% precision, finding Ï8=0.811±0.006. We find consistency with the lensing results from the Dark Energy Survey, and give combined lensing-only parameter constraints that are tighter than joint results using galaxy clustering. Using Planck cosmic infrared background (CIB) maps we make a combined estimate of the lensing potential over 60% of the sky with considerably more small-scale signal. We demonstrate delensing of the Planck power spectra, detecting a maximum removal of 40% of the lensing-induced power in all spectra. The improvement in the sharpening of the acoustic peaks by including both CIB and the quadratic lensing reconstruction is detected at high significance (abridged)
Planck intermediate results. XLIX. Parity-violation constraints from polarization data
Parity-violating extensions of the standard electromagnetic theory cause in vacuo rotation of the plane of polarization of propagating photons. This effect, also known as cosmic birefringence, has an impact on the cosmic microwave background (CMB) anisotropy angular power spectra, producing non-vanishing TâB and EâB correlations that are otherwise null when parity is a symmetry. Here we present new constraints on an isotropic rotation, parametrized by the angle α, derived from Planck 2015 CMB polarization data. To increase the robustness of our analyses, we employ two complementary approaches, in harmonic space and in map space, the latter based on a peak stacking technique. The two approaches provide estimates for α that are in agreement within statistical uncertainties and are very stable against several consistency tests.Considering the TâB and EâB information jointly, we find from the harmonic analysis and from the stacking approach. These constraints are compatible with no parity violation and are dominated by the systematic uncertainty in the orientation of Planckâs polarization-sensitive bolometers
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