Optimal focal-plane restoration

Image restoration can be implemented efficiently by calculating the convolution of the digital image and a small kernel during image acquisition. Processing the image in the focal-plane in this way requires less computation than traditional Fourier-transform-based techniques such as the Wiener filter and constrained least-squares filter. Here, the values of the convolution kernel that yield the restoration with minimum expected mean-square error are determined using a frequency analysis of the end-to-end imaging system. This development accounts for constraints on the size and shape of the spatial kernel and all the components of the imaging system. Simulation results indicate the technique is effective and efficient

Quantitative analysis of the reconstruction performance of interpolants

The analysis presented provides a quantitative measure of the reconstruction or interpolation performance of linear, shift-invariant interpolants. The performance criterion is the mean square error of the difference between the sampled and reconstructed functions. The analysis is applicable to reconstruction algorithms used in image processing and to many types of splines used in numerical analysis and computer graphics. When formulated in the frequency domain, the mean square error clearly separates the contribution of the interpolation method from the contribution of the sampled data. The equations provide a rational basis for selecting an optimal interpolant; that is, one which minimizes the mean square error. The analysis has been applied to a selection of frequently used data splines and reconstruction algorithms: parametric cubic and quintic Hermite splines, exponential and nu splines (including the special case of the cubic spline), parametric cubic convolution, Keys' fourth-order cubic, and a cubic with a discontinuous first derivative. The emphasis in this paper is on the image-dependent case in which no a priori knowledge of the frequency spectrum of the sampled function is assumed

Digital enhancement of flow field images

Most photographs of experimentally generated fluid flow fields have inherently poor photographic quality, specifically low contrast. Thus, there is a need to establish a process for quickly and accurately enhancing these photographs to provide improved versions for physical interpretation, analysis, and publication. A sequence of digital image processing techniques which have been demonstrated to effectively enhance such photographs is described

Distortion of magnetotelluric sounding curves by three‐dimensional structures

Distortions of magnetotelluric fields caused by threedimensional (3-D) structures can be severe and are not predictable using one-dimensional or two-dimensional modeling. I used a 3-D modeling algorithm based upon an extension of a generalized thin sheet analysis due to Ranganayaki and Madden (1980) to examine field distortions in crustal environments. Three major physical mechanisms cause these distortions. These mechanisms are resistive coupling between the electrical mantle and upper crust, resistive coupling between conductive features within the upper crust, and local induction of current loops within good conductors. Each mechanism produces different spatial and frequency effects upon the background field, so identification of the dominant mechanism can be used as an interpretational aid. I finally use this analysis to identify distortion mechanisms seen in magnetotelluric data from Beowawe, Nevada to aid in an interpretation of that area.United States. Geological SurveyUnited States. Department of EnergyChevron CorporationMassachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Science

Tensor Minkowski Functionals for random fields on the sphere

We generalize the translation invariant tensor-valued Minkowski Functionals which are defined on two-dimensional flat space to the unit sphere. We apply them to level sets of random fields. The contours enclosing boundaries of level sets of random fields give a spatial distribution of random smooth closed curves. We obtain analytic expressions for the ensemble expectation values for the matrix elements of the tensor-valued Minkowski Functionals for isotropic Gaussian and Rayleigh fields. We elucidate the way in which the elements of the tensor Minkowski Functionals encode information about the nature and statistical isotropy (or departure from isotropy) of the field. We then implement our method to compute the tensor-valued Minkowski Functionals numerically and demonstrate how they encode statistical anisotropy and departure from Gaussianity by applying the method to maps of the Galactic foreground emissions from the PLANCK data.Comment: 1+23 pages, 5 figures, Significantly expanded from version 1. To appear in JCA

Electrical conductivity images of Quaternary faults and Tertiary detachments in the California Basin and Range

Comparison of an electrical resistivity section derived from magnetotelluric (MT) data to a geologic section extending eastward from the Sierra Nevada near latitude 36°20′N shows that the crust is dominated by steeply dipping conductive features that correlate with active strike-slip faults. While there is a subhorizontal conductor at a depth ∼20 km beneath some of the profile, it is broken by vertical structures associated with the active strike-slip faults. The continuous subhorizontal anomalies in the lower crust typically observed in extensional regions are therefore absent in the resistivity section. The present-day strike-slip tectonic regime as indicated by geodetic data in this part of the Basin and Range is not producing features that could be inferred to indicate subhorizontal shear zones resulting from lateral crustal flow during extension. Because the Miocene tectonic regime resulted in the formation of metamorphic core complexes and thus was accompanied by such flow, the present regime appears to represent a fundamental transition in the mode of crustal deformation in the region. A serendipitous result of our study was the identification on resistivity sections of carbonate aquifers in the upper crust. Comparison of resistivities from the MT section to measured fluid resistivities from springs and boreholes suggests that the aquifers must be heterogeneous, with more saline brines occupying the deepest portions of the carbonates

Tribunalizing Sovereign Debt: Argentina\u27s Experience with Investor-State Dispute Settlement

The global sovereign debt market, lacking a formal bankruptcy regime or binding regulatory oversight, is fundamentally shaped by the specter of conflicts between debtors that refuse to pay and holdout creditors that refuse to settle. Never was this more evident than in Argentina\u27s most recent sovereign debt crisis, which spurred daring, innovative, and often controversial legal strategies. This Article focuses on one of the legacies of Argentina\u27s sovereign debt crisis: the use of investor-state arbitration under international investment law to enforce sovereign bond contracts. Following Argentina\u27s financial collapse in 2001, private creditors brought dozens of cases against Argentina before the International Center for the Settlement of Investment Disputes (ICSID). Among these ICSID cases was Abaclat and Others v. The Argentine Republic, which marked the first time that an arbitral tribunal ruled that it had jurisdiction to rule on a sovereign debt default and restructuring under international investment law. With the proliferation of investor-state dispute settlement (ISDS) mechanisms in bilateral investment treaties (BITs) and other international investment agreements, this remedy will likely grow in importance. In light of Abaclat and subsequent ICSID cases, this Article analyzes Argentina\u27s experience with sovereign debt claims under BITs in the broader context of sovereign debt disputes and ongoing measures undertaken by sovereigns in response to tribunalization. Looking forward, this Article assesses the systemic implications of ISDS for the exercise of sovereign authority in sovereign debt finance

Should you use antibiotics to treat acute otitis media in children?

Antibiotics are not necessary to treat uncomplicated acute otitis media (AOM) in an otherwise healthy child (strength of recommendation [SOR]: A, systematic review). Children younger than 2 years and children with bilateral infection, high fever, or vomiting may experience modest symptom relief from antibiotics (SOR: B, cohort studies)