Phase retrieval for characteristic functions of convex bodies and reconstruction from covariograms

We propose strongly consistent algorithms for reconstructing the characteristic function 1_K of an unknown convex body K in R^n from possibly noisy measurements of the modulus of its Fourier transform \hat{1_K}. This represents a complete theoretical solution to the Phase Retrieval Problem for characteristic functions of convex bodies. The approach is via the closely related problem of reconstructing K from noisy measurements of its covariogram, the function giving the volume of the intersection of K with its translates. In the many known situations in which the covariogram determines a convex body, up to reflection in the origin and when the position of the body is fixed, our algorithms use O(k^n) noisy covariogram measurements to construct a convex polytope P_k that approximates K or its reflection -K in the origin. (By recent uniqueness results, this applies to all planar convex bodies, all three-dimensional convex polytopes, and all symmetric and most (in the sense of Baire category) arbitrary convex bodies in all dimensions.) Two methods are provided, and both are shown to be strongly consistent, in the sense that, almost surely, the minimum of the Hausdorff distance between P_k and K or -K tends to zero as k tends to infinity.Comment: Version accepted on the Journal of the American Mathematical Society. With respect to version 1 the noise model has been greatly extended and an appendix has been added, with a discussion of rates of convergence and implementation issues. 56 pages, 4 figure

Inverse diffraction for the Atmospheric Imaging Assembly in the Solar Dynamics Observatory

The Atmospheric Imaging Assembly in the Solar Dynamics Observatory provides full Sun images every 1 seconds in each of 7 Extreme Ultraviolet passbands. However, for a significant amount of these images, saturation affects their most intense core, preventing scientists from a full exploitation of their physical meaning. In this paper we describe a mathematical and automatic procedure for the recovery of information in the primary saturation region based on a correlation/inversion analysis of the diffraction pattern associated to the telescope observations. Further, we suggest an interpolation-based method for determining the image background that allows the recovery of information also in the region of secondary saturation (blooming)

PROFITING FROM CUSTOMER DATA: A PROPOSED RESEARCH AGENDA

The unprecedented volume of data captured by modern hospitality firms during the co-production of the service experience can be used to create economic value. In this article we describe two frameworks grounded in the cross-disciplinary literature in information systems, strategy and marketing, that can help in conceptualizing future research directions in this area. In the first framework, the IS cycle describes the process by which data, generated by transaction processing systems, become the basis for future analyses and initiatives. The second framework enables a disciplined industry analysis by allowing for joint evaluation of the theoretical repurchase rate, degree of customizability of products and services, and degree of unobtrusive data capture that characterizes a given firm’s value proposition. This paper focuses on setting the theoretical framework of reference. A discussion of future research directions and propositions is reserved for the conference presentation due to space limitations

Point-to-Point: Telecommunications Networks from the Optical Telegraph to the Mobile Telephone

This chapter surveys the history of telecommunications from a global perspective and highlights three influential interpretative traditions. It has two parts. The first part defines “telecommunications” and sketches the main dimensions of four telecommunications networks over a two-hundred-year period—the optical telegraph, the electric telegraph, the landline telephone, and the mobile telephone (and its predecessor, the wireless telegraph). The second part shows how historical scholarship on topics in the history of telecommunications has been shaped by three intellectual traditions: the Large Technical Systems (LTS) approach; political economy; and the Social Construction of Technology (SCOT)

Toward the Design of Highly Efficient, Readily Accessible Peptide N-caps for the Induction of Helical Conformations

A series of novel peptide N-caps was designed with an emphasis on ease of synthesis and an abundance of hydrogen bond acceptors. Different scaffolds based on sugars, cyclic hydrocarbons, and amino acids are developed with a variety of hydrogen bond acceptors including esters, carboxyls, amides and a sulfonic acid. The efficient use in solid-phase peptide synthesis was demonstrated by incorporating the N-caps to a resin-bound model peptide. Their differential helix nucleating power in aqueous buffer was determined by CD studies. Increases in peptide helicity to a significant extent are observed, leading to a discussion of N-capping efficiency versus ease of synthesis. The potential of the elaborated N-caps for the reversal of β-sheet to α-helix conformations in the context of fibrillogenesis is discusse

Tanaidacea (Crustacea: Peracardia) of the Gulf of Mexico. VII. Atlantapseudes lindae, N. Sp. (Apseudidae) from the Continental Slope of the Northern Gulf of Mexico

During 1983 through 1985, 53 specimens of Atlantapseudes lindae, new species, were collected in box core samples taken on the continental slope in the northern Gulf of Mexico. Atlantapseudes lindae can be distinguished from the only other member of the genus, A. nigrichela Băcescu, 1978 by several characters, including the length of the squama of antenna 2, which is no longer than the third peduncular segment, and the absence of anterolateral spines on pereonites 1-2 of females and 1-6 on males. The diagnosis for genus Atlantapseudes Băcescu, 1978 is amended to include the presence of sexually dimorphic chelae and first antennae in fully developed males