Toward fault-tolerant quantum computation without concatenation

It has been known that quantum error correction via concatenated codes can be done with exponentially small failure rate if the error rate for physical qubits is below a certain accuracy threshold. Other, unconcatenated codes with their own attractive features-improved accuracy threshold, local operations-have also been studied. By iteratively distilling a certain two-qubit entangled state it is shown how to perform an encoded Toffoli gate, important for universal computation, on CSS codes that are either unconcatenated or, for a range of very large block sizes, singly concatenated.Comment: 12 pages, 2 figures, replaced: new stuff on error models, numerical example for concatenation criteri

Bohr Hamiltonian with deformation-dependent mass term for the Kratzer potential

The Deformation Dependent Mass (DDM) Kratzer model is constructed by considering the Kratzer potential in a Bohr Hamiltonian, in which the mass is allowed to depend on the nuclear deformation, and solving it by using techniques of supersymmetric quantum mechanics (SUSYQM), involving a deformed shape invariance condition. Analytical expressions for spectra and wave functions are derived for separable potentials in the cases of gamma-unstable nuclei, axially symmetric prolate deformed nuclei, and triaxial nuclei, implementing the usual approximations in each case. Spectra and B(E2) transition rates are compared to experimental data. The dependence of the mass on the deformation, dictated by SUSYQM for the potential used, moderates the increase of the moment of inertia with deformation, removing a main drawback of the model.Comment: 27 pages, 6 figures, 8 tables. arXiv admin note: text overlap with arXiv:1103.593

Abradable compressor and turbine seals, volume 1

The application and advantages of abradable coatings as gas-path seals in a general aviation turbine engine were evaluated for use on the high-pressure compressor, the high-pressure turbine, and the low-pressure turbine shrouds. Topics covered include: (1) the initial selection of candidate materials for interim full-scale engine testing; (2) interim engine testing of the initially selected materials and additional candidate materials; (3) the design of the component required to adapt the hardware to permit full-scale engine testing of the most promising materials; (4) finalization of the fabrication methods used in the manufacture of engine test hardware; and (5) the manufacture of the hardware necessary to support the final full-scale engine tests

Abradable compressor and turbine seals, volume 2

The applications and advantages of abradable coatings as gas path seals in a general aviation turbofan engine were investigated. Abradable materials were evaluated for the high pressure radial compressor and the axial high and low pressure turbine shrouds

Competing during a pandemic? Retailers’ ups and downs during the COVID-19 outbreak

The COVID-19 pandemic (that started in early 2020) is causing several disruptions in the short- and mid-term, to which businesses have to adapt. Some retailers have reacted to the emergency immediately, displaying a plethora of different intervention types. The authors aim to synthesize the challenges that retailers are facing during the COVID-19 emergency. We do this from the perspective of both consumers and managers, with the goal of providing guidelines on and examples of how retailers can handle this unprecedented situation

Programmable hash functions and their applications

We introduce a new combinatorial primitive called *programmable hash functions* (PHFs). PHFs can be used to *program* the output of a hash function such that it contains solved or unsolved discrete logarithm instances with a certain probability. This is a technique originally used for security proofs in the random oracle model. We give a variety of *standard model* realizations of PHFs (with different parameters). The programmability makes PHFs a suitable tool to obtain black-box proofs of cryptographic protocols when considering adaptive attacks. We propose generic digital signature schemes from the strong RSA problem and from some hardness assumption on bilinear maps that can be instantiated with any PHF. Our schemes offer various improvements over known constructions. In particular, for a reasonable choice of parameters, we obtain short standard model digital signatures over bilinear maps

The Mesoamerican Corpus of Formative Period Art and Writing

This project explores the origins and development of the first writing in the New World by constructing a comprehensive database of Formative period, 1500-400 BCE, iconography and a suite of database-driven digital tools. In collaboration with two of the largest repositories of Formative period Mesoamerican art in Mexico, the project integrates the work of archaeologists, art historians, and scientific computing specialists to plan and begin the production of a database, digital assets, and visual search software that permit the visualization of spatial, chronological, and contextual relationships among iconographic and archaeological datasets. These resources will eventually support mobile and web based applications that allow for the search, comparison, and analysis of a corpus of material currently only partially documented. The start-up phase will generate a functional prototype database, project website, wireframe user interfaces, and a report summarizing project development