1,383 research outputs found
In situ measurements of Arctic atmospheric trace constituents from an aircraft
In situ measurements of the ambient concentrations of several atmospheric trace constituents were obtained using instruments installed on board the NASA Convair 990 aircraft at altitudes up to 12.5 kilometers over Alaska and the Arctic Ocean. Concentration data on ozone, carbon monoxide, water vapor, and particles larger than 0.5 micrometer in diameter were acquired
A Bell-type test of energy-time entangled qutrits
We have performed a Bell-type test for energy-time entangled qutrits. A
method of inferring the Bell violation in terms of an associated interference
visibility is derived. Using this scheme we obtained a Bell value of , representing a violation of above the limit for local
variables. The scheme has been developed for use at telecom wavelengths and
using proven long distance quantum communication architecture to optimize the
utility of this high dimensional entanglement resource.Comment: replaced lost acknowledement
Bounds on the Probability of Success of Postselected Non-linear Sign Shifts Implemented with Linear Optics
The fundamental gates of linear optics quantum computation are realized by
using single photons sources, linear optics and photon counters. Success of
these gates is conditioned on the pattern of photons detected without using
feedback. Here it is shown that the maximum probability of success of these
gates is typically strictly less than 1. For the one-mode non-linear sign
shift, the probability of success is bounded by 1/2. For the conditional sign
shift of two modes, this probability is bounded by 3/4. These bounds are still
substantially larger than the highest probabilities shown to be achievable so
far, which are 1/4 and 2/27, respectively.Comment: 6 page
Office of Space Science: Integrated technology strategy
This document outlines the strategy by which the Office of Space Science, in collaboration with the Office of Advanced Concepts and Technology and the Office of Space Communications, will meet the challenge of the national technology thrust. The document: highlights the legislative framework within which OSS must operate; evaluates the relationship between OSS and its principal stakeholders; outlines a vision of a successful OSS integrated technology strategy; establishes four goals in support of this vision; provides an assessment of how OSS is currently positioned to respond to the goals; formulates strategic objectives to meet the goals; introduces policies for implementing the strategy; and identifies metrics for measuring success. The OSS Integrated Technology Strategy establishes the framework through which OSS will satisfy stakeholder expectations by teaming with partners in NASA and industry to develop the critical technologies required to: enhance space exploration, expand our knowledge of the universe, and ensure continued national scientific, technical and economic leadership
Classical simulation of noninteracting-fermion quantum circuits
We show that a class of quantum computations that was recently shown to be
efficiently simulatable on a classical computer by Valiant corresponds to a
physical model of noninteracting fermions in one dimension. We give an
alternative proof of his result using the language of fermions and extend the
result to noninteracting fermions with arbitrary pairwise interactions, where
gates can be conditioned on outcomes of complete von Neumann measurements in
the computational basis on other fermionic modes in the circuit. This last
result is in remarkable contrast with the case of noninteracting bosons where
universal quantum computation can be achieved by allowing gates to be
conditioned on classical bits (quant-ph/0006088).Comment: 26 pages, 1 figure, uses wick.sty; references added to recent results
by E. Knil
Feasibility of therapeutic pneumoperitoneum in a large animal model using a microvaporisator
Background: Multimodal therapy is used increasingly in advanced gastrointestinal tumors. Potential benefits of using an intraoperative adjuvant therapy during laparoscopy for cancer have been documented in animal studies. The aim of this study was to develop a device that could deliver such an intraoperative drug therapy. Methods: We developed a micropump suitable for minimally invasive surgery procedures that allowed microdroplets of therapeutic substance to be distributed into the pneumoperitoneum (CO2), creating a "therapeutic pneumoperitoneum.” A closed-loop control system regulates drug delivery according to the gas flow. In vitro, the micropump is able to aerosolize various aqueous and ethanol solutions, including cytostatic and bacteriostatic drugs and adhesionmodulating agents. The size of the microdroplets has been optimized to prevent visual artifacts. Results: The micropump was tested in an animal model (pig). The system was inserted into a 5-mm trocar. After insufflation of a 12-mm CO2 pneumoperitoneum, laparoscopic sigmoid colon resections could be performed with no special difficulties. No fog developed, and no systemrelated complication was observed. At autopsy, the active principle was distributed to all exposed peritoneal surfaces. Conclusions: As opposed to conventional peritoneal washing, therapeutic pneumoperitoneum reaches the entire peritoneal surface, allowing an optimal drug distribution. Drug diffusion into the tissues is enhanced by the intraperitoneal pressure. Precise determination of the instantaneous and total drug quantity is possible. Therefore, this drug delivery system has several advantages over conventional irrigation. Its potential domains of application are locoregional cancer therapy, prevention of port-site recurrences, immunomodulation, analgesia, peritonitis, and prevention of postoperative adhesion
Characterization of the Mutagenic Spectrum of 4-Nitroquinoline 1-Oxide (4-NQO) in Aspergillus nidulans by Whole Genome Sequencing
4-Nitroquinoline 1-oxide (4-NQO) is a highly carcinogenic chemical that induces mutations in bacteria, fungi, and animals through the formation of bulky purine adducts. 4-NQO has been used as a mutagen for genetic screens and in both the study of DNA damage and DNA repair. In the model eukaryote Aspergillus nidulans, 4-NQO−based genetic screens have been used to study diverse processes, including gene regulation, mitosis, metabolism, organelle transport, and septation. Early work during the 1970s using bacterial and yeast mutation tester strains concluded that 4-NQO was a guanine-specific mutagen. However, these strains were limited in their ability to determine full mutagenic potential, as they could not identify mutations at multiple sites, unlinked suppressor mutations, or G:C to C:G transversions. We have now used a whole genome resequencing approach with mutant strains generated from two independent genetic screens to determine the full mutagenic spectrum of 4-NQO in A. nidulans. Analysis of 3994 mutations from 38 mutant strains reveals that 4-NQO induces substitutions in both guanine and adenine residues, although with a 19-fold preference for guanine. We found no association between mutation load and mutagen dose and observed no sequence bias in the residues flanking the mutated purine base. The mutations were distributed randomly throughout most of the genome. Our data provide new evidence that 4-NQO can potentially target all base pairs. Furthermore, we predict that current practices for 4-NQO−induced mutagenesis are sufficient to reach gene saturation for genetic screens with feasible identification of causative mutations via whole genome resequencing
Mode structure and photon number correlations in squeezed quantum pulses
The question of efficient multimode description of optical pulses is studied.
We show that a relatively very small number of nonmonochromatic modes can be
sufficient for a complete quantum description of pulses with Gaussian
quadrature statistics. For example, a three-mode description was enough to
reproduce the experimental data of photon number correlations in optical
solitons [S. Spalter et al., Phys. Rev. Lett. 81, 786 (1998)]. This approach is
very useful for a detailed understanding of squeezing properties of soliton
pulses with the main potential for quantum communication with continuous
variables. We show how homodyne detection and/or measurements of photon number
correlations can be used to determine the quantum state of the multi-mode
field. We also discuss a possible way of physical separation of the
nonmonochromatic modes.Comment: 14 pages, 4 figures; minor revisions of the text, new references; to
appear in the Phys. Rev.
Material system analysis: Characterization of flows, stocks, and performance indicators of manganese, nickel, and natural graphite in the EU, 2012–2016
Raw materials form an industrial base to provide the wide range of products and services demanded by industry and society. In particular, manganese, nickel, and natural graphite are examples of materials having a globally consolidated supply chain with interlinked use in steelmaking and essential role in clean energy systems and e-mobility. A stable material supply chain is hence a priority for import-dependent regions like the EU and builds upon quantitative system understanding. To this aim, the EU Material System Analysis is applied to analyze the anthropogenic cycle of manganese, nickel, and natural graphite from 2012 to 2016. We provide a detailed characterization of their material stocks, flows, and changes in selected performance indicators including end-of-life recycling rate (51% +/- 3%, 49% +/- 8%, and 8% +/- 0% for manganese, nickel, and natural graphite, respectively), self-sufficiency potential (40% +/- 3%, 32% +/- 5%, and 5% +/- 1%), old scrap ratio (31% +/- 0%, 22% +/- 2%, and 90% +/- 1%), recycling input rate (25% +/- 1%, 38% +/- 2%, and 3% +/- 0%), recycling process efficiency rate (84% +/- 2%, 85% +/- 6%, and 48% +/- 3%), and pre-consumer losses rate (83% +/- 3%, 5% +/- 1%, and 24% +/- 2%). The achieved results may inform decision-makers engaged with raw materials recovery and recycling as well as the strategic securement of a reliable material supply to the EU for resilient industrial ecosystems
Quantum state transformation by dispersive and absorbing four-port devices
The recently derived input-output relations for the radiation field at a
dispersive and absorbing four-port device [T. Gruner and D.-G. Welsch, Phys.
Rev. A 54, 1661 (1996)] are used to derive the unitary transformation that
relates the output quantum state to the input quantum state, including
radiation and matter and without placing frequency restrictions. It is shown
that for each frequency the transformation can be regarded as a well-behaved
SU(4) group transformation that can be decomposed into a product of U(2) and
SU(2) group transformations. Each of them may be thought of as being realized
by a particular lossless four-port device. If for narrow-bandwidth radiation
far from the medium resonances the absorption matrix of the four-port device
can be disregarded, the well-known SU(2) group transformation for a lossless
device is recognized. Explicit formulas for the transformation of Fock-states
and coherent states are given.Comment: 24 pages, RevTe
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