16,787 research outputs found
iCapture: Facilitating Spontaneous User-Interaction with Pervasive Displays using Smart Devices
Abstract. The eCampus project at Lancaster University is an inter-disciplinary project aiming to deploy a wide range of situated displays across the University campus in order to create a large per-vasive communications infrastructure. At present, we are conducting a series of parallel research activities in order to investigate how the pervasive communications infrastructure can support the daily needs of staff, students and visitors to the University. This paper introduces one of our current research investigations into how one is able to mediate spontaneous interaction with the pervasive display infrastructure through camera equipped mobile phones (i.e. smart devices).
Quantum Algorithms for Fermionic Quantum Field Theories
Extending previous work on scalar field theories, we develop a quantum
algorithm to compute relativistic scattering amplitudes in fermionic field
theories, exemplified by the massive Gross-Neveu model, a theory in two
spacetime dimensions with quartic interactions. The algorithm introduces new
techniques to meet the additional challenges posed by the characteristics of
fermionic fields, and its run time is polynomial in the desired precision and
the energy. Thus, it constitutes further progress towards an efficient quantum
algorithm for simulating the Standard Model of particle physics.Comment: 29 page
Quantum Algorithms for Quantum Field Theories
Quantum field theory reconciles quantum mechanics and special relativity, and
plays a central role in many areas of physics. We develop a quantum algorithm
to compute relativistic scattering probabilities in a massive quantum field
theory with quartic self-interactions (phi-fourth theory) in spacetime of four
and fewer dimensions. Its run time is polynomial in the number of particles,
their energy, and the desired precision, and applies at both weak and strong
coupling. In the strong-coupling and high-precision regimes, our quantum
algorithm achieves exponential speedup over the fastest known classical
algorithm.Comment: v2: appendix added (15 pages + 25-page appendix
Quantum Computation of Scattering in Scalar Quantum Field Theories
Quantum field theory provides the framework for the most fundamental physical theories to be confirmed experimentally, and has enabled predictions of unprecedented precision. However, calculations of physical observables often require great computational complexity and can generally be performed only when the interaction strength is weak. A full understanding of the foundations and rich consequences of quantum field theory remains an outstanding challenge. We develop a quantum algorithm to compute relativistic scattering amplitudes in massive phi-fourth theory in spacetime of four and fewer dimensions. The algorithm runs in a time that is polynomial in the number of particles, their energy, and the desired precision, and applies at both weak and strong coupling. Thus, it offers exponential speedup over existing classical methods at high precision or strong coupling
The use of phenyl-Sepharose for the affinity purification of proteinases
Phenyl-Sepharose is most often used as an adsorbent for hydrophobic interaction chromatography (HIC). We report on its effective use for the affinity purification of some extracellular thermostable proteinases from bacterial sources. Proteinases belonging to the serine, aspartate and metallo mechanistic classes were effective retained by the media. Purification factors in the range of 2.9–60 and enzyme activity yields in excess of 88% were obtained. In some cases homogeneous enzyme was obtained from culture supernatants in a single step. A number of other proteinases from mammalian sources were also retained. The specificity of the enzyme/support interaction was studied. Proteinases complexed with peptide inhibitors (pepstatin and chymostatin) showed reduced binding to phenyl Sepharose indicating with the active site cleft whereas modification with low molecular weight active site directed inactivators such as PMSF and DAN did not, indicating that binding may not be dependent on the catalytic site. Pepsinogen and the pro-enzyme form of the serine proteinase from the thermophilic Bacillus sp. strain Ak.1 were not retained by the media and could be resolved in an efficient manner from their active counterparts
BQP-completeness of Scattering in Scalar Quantum Field Theory
Recent work has shown that quantum computers can compute scattering
probabilities in massive quantum field theories, with a run time that is
polynomial in the number of particles, their energy, and the desired precision.
Here we study a closely related quantum field-theoretical problem: estimating
the vacuum-to-vacuum transition amplitude, in the presence of
spacetime-dependent classical sources, for a massive scalar field theory in
(1+1) dimensions. We show that this problem is BQP-hard; in other words, its
solution enables one to solve any problem that is solvable in polynomial time
by a quantum computer. Hence, the vacuum-to-vacuum amplitude cannot be
accurately estimated by any efficient classical algorithm, even if the field
theory is very weakly coupled, unless BQP=BPP. Furthermore, the corresponding
decision problem can be solved by a quantum computer in a time scaling
polynomially with the number of bits needed to specify the classical source
fields, and this problem is therefore BQP-complete. Our construction can be
regarded as an idealized architecture for a universal quantum computer in a
laboratory system described by massive phi^4 theory coupled to classical
spacetime-dependent sources.Comment: 41 pages, 7 figures. Corrected typo in foote
NASA's progress in nuclear electric propulsion technology
The National Aeronautics and Space Administration (NASA) has established a requirement for Nuclear Electric Propulsion (NEP) technology for robotic planetary science mission applications with potential future evolution to systems for piloted Mars vehicles. To advance the readiness of NEP for these challenging missions, a near-term flight demonstration on a meaningful robotic science mission is very desirable. The requirements for both near-term and outer planet science missions are briefly reviewed, and the near-term baseline system established under a recent study jointly conducted by the Lewis Research Center (LeRC) and the Jet Propulsion Laboratory (JPL) is described. Technology issues are identified where work is needed to establish the technology for the baseline system, and technology opportunities which could provide improvement beyond baseline capabilities are discussed. Finally, the plan to develop this promising technology is presented and discussed
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