941 research outputs found
Nonclassical Degrees of Freedom in the Riemann Hamiltonian
The Hilbert-Polya conjecture states that the imaginary parts of the zeros of
the Riemann zeta function are eigenvalues of a quantum hamiltonian. If so,
conjectures by Katz and Sarnak put this hamiltonian in Altland and Zirnbauer's
universality class C. This implies that the system must have a nonclassical
two-valued degree of freedom. In such a system, the dominant primitive periodic
orbits contribute to the density of states with a phase factor of -1. This
resolves a previously mysterious sign problem with the oscillatory
contributions to the density of the Riemann zeros.Comment: 4 pages, no figures; v3-6 have minor corrections to v2, v2 has a more
complete solution of the sign problem than v
V/STOL lift fan commercial short haul transports: Continuing conceptual design study
A design study of commercial V/STOL transport airplanes for a 1985 operational time period has been made. The baseline mission considered was 400 nmi at a cruise speed of M = 0.75 and a 100-passenger payload with VTOL. Variations from the baseline included mission distance, payload, cruise speed, and propulsion system failure philosophy. All designs used propulsion systems consisting of multiple gas generators driving remote tip turbine lift and lift/cruise fans. By considering the fan to be designed for operational reliability, significant simplication of the airplane systems and reduction in airplane size and cost can be achieved
Notes on the use and interpretation of radiostereometric analysis
ABSTRACT With increasing numbers of research groups carrying out radiostereometric analysis (RSA), it is important to reach a consensus on how the main aspects of the technique should be carried out and how the results should be presented in an appropriate and consistent way
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Coal liquefaction process streams characterization and evaluation
This study demonstrated the feasibility of using fluorescence and reflectance microscopy techniques for the examination of distillation resid materials derived from direct coal liquefaction. Resid, as defined here, is the 850{degrees}F{sup +} portion of the process stream, and includes soluble organics, insoluble organics and ash. The technique can be used to determine the degree of hydrogenation and the presence of multiple phases occurring within a resid sample. It can also be used to infer resid reactivity. The technique is rapid, requiring less than one hour for sample preparation and examination, and thus has apparent usefulness for process monitoring. Additionally, the technique can distinguish differences in samples produced under various process conditions. It can, therefore, be considered a potentially useful technique for the process developer. Further development and application of this analytical method as a process development tool is justified based on these results
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Coal liquefaction process streams characterization and evaluation. Novel analytical techniques for coal liquefaction: Fluorescence microscopy
This study demonstrated the feasibility of using fluorescence and reflectance microscopy techniques for the examination of distillation resid materials derived from direct coal liquefaction. Resid, as defined here, is the 850{degrees}F{sup +} portion of the process stream, and includes soluble organics, insoluble organics and ash. The technique can be used to determine the degree of hydrogenation and the presence of multiple phases occurring within a resid sample. It can also be used to infer resid reactivity. The technique is rapid, requiring less than one hour for sample preparation and examination, and thus has apparent usefulness for process monitoring. Additionally, the technique can distinguish differences in samples produced under various process conditions. It can, therefore, be considered a potentially useful technique for the process developer. Further development and application of this analytical method as a process development tool is justified based on these results
Application of the microhole and strip plate detector for neutron detection
We introduce the microhole and strip plate (MHSP) detector as a micropattern detector for the detection of thermal and epithermal neutrons. Detection sensitivity is obtained by filling these detectors with 3He at high pressures. We propose the use of argon-xenon penning mixtures as the stopping gas as opposed to the usual carbon based stopping gases. These argon-xenon mixtures provide suitable gas gains for the high pressure/high resolution neutron detector applications. With these mixtures it is possible to obtain a sealed detector with only rare-gas filling which is simple to purify and not subject to ageing. An MHSP gas detector filled with a 3-bar argon/50-mbar xenon/6-bar helium mixture can achieve gains above 2×103. This mixture allows neutron detection efficiencies of about 70% at 1 Å for a 2.5-cm thick absorption region and intrinsic position resolution (full-width at half-maximum) of about 1.8 mm. The sensitivity to γ-rays of the present mixture will be the same when compared to that of 2.6-bar CF
Food for our future: the nutritional science behind the sustainable fungal protein - mycoprotein. A symposium review.
This is the final version. Available from Cambridge University Press via the DOI in this record. Mycoprotein is a well-established and sustainably produced, protein-rich, high-fibre, whole food source derived from the fermentation of fungus. The present publication is based on a symposium held during the Nutrition Society Summer Conference 2022 in Sheffield that explored 'Food for our Future: The Science Behind Sustainable Fungal Proteins'. A growing body of science links mycoprotein consumption with muscle/myofibrillar protein synthesis and improved cardiometabolic (principally lipid) markers. As described at this event, given the accumulating health and sustainability credentials of mycoprotein, there is great scope for fungal-derived mycoprotein to sit more prominently within future, updated food-based dietary guidelines.Marlow Foods Ltd
Application of the microhole and strip plate detector for neutron detection
We introduce the microhole and strip plate (MHSP) detector as a micropattern detector for the detection of thermal and epithermal neutrons. Detection sensitivity is obtained by filling these detectors with 3He at high pressures. We propose the use of argon-xenon penning mixtures as the stopping gas as opposed to the usual carbon based stopping gases. These argon-xenon mixtures provide suitable gas gains for the high pressure/high resolution neutron detector applications. With these mixtures it is possible to obtain a sealed detector with only rare-gas filling which is simple to purify and not subject to ageing. An MHSP gas detector filled with a 3-bar argon/50-mbar xenon/6-bar helium mixture can achieve gains above 2×103. This mixture allows neutron detection efficiencies of about 70% at 1 Å for a 2.5-cm thick absorption region and intrinsic position resolution (full-width at half-maximum) of about 1.8 mm. The sensitivity to γ-rays of the present mixture will be the same when compared to that of 2.6-bar CF
Proton endor study of the photoexcited triplet state PT in Rps. sphaeroides R-26 photosynthetic reaction centres
The photoexcited triplet state PT of Rhodopseudomonas sphaeroides R-26 has been investigated by ENDOR measurements performed on frozen photosynthetic reaction centre solutions. For the first time hyperfine data could be obtained for PT. These data indicate a delocalisation of the triplet state over two bacteriochlorophyll a molecules
Revisiting the Local Scaling Hypothesis in Stably Stratified Atmospheric Boundary Layer Turbulence: an Integration of Field and Laboratory Measurements with Large-eddy Simulations
The `local scaling' hypothesis, first introduced by Nieuwstadt two decades
ago, describes the turbulence structure of stable boundary layers in a very
succinct way and is an integral part of numerous local closure-based numerical
weather prediction models. However, the validity of this hypothesis under very
stable conditions is a subject of on-going debate. In this work, we attempt to
address this controversial issue by performing extensive analyses of turbulence
data from several field campaigns, wind-tunnel experiments and large-eddy
simulations. Wide range of stabilities, diverse field conditions and a
comprehensive set of turbulence statistics make this study distinct
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