2,636 research outputs found
Radiant Emission Characteristics of Diffuse Conical Cavities
Radiant-energy emission of diffuse conical cavitie
Thermal Radiation Absorption in Rectangular-Groove Cavities
Thermal radiation absorption in rectangular-groove cavitie
Absorption and Emission Characteristics of Diffuse Spherical Enclosures
The thermal radiation characteristics of spherical cavities are of practical interest in connection with the absorption of radiant energy for both space-vehicle and terrestrial applications. Also, spherical cavities are of potential use as sources of black-body energy. The purpose of this brief paper is to determine both the absorption and emission characteristics of spherical cavities which are diffuse reflectors and emitters
Scaling and synchronization in a ring of diffusively coupled nonlinear oscillators
Chaos synchronization in a ring of diffusively coupled nonlinear oscillators
driven by an external identical oscillator is studied. Based on numerical
simulations we show that by introducing additional couplings at -th
oscillators in the ring, where is an integer and is the maximum
number of synchronized oscillators in the ring with a single coupling, the
maximum number of oscillators that can be synchronized can be increased
considerably beyond the limit restricted by size instability. We also
demonstrate that there exists an exponential relation between the number of
oscillators that can support stable synchronization in the ring with the
external drive and the critical coupling strength with a scaling
exponent . The critical coupling strength is calculated by numerically
estimating the synchronization error and is also confirmed from the conditional
Lyapunov exponents (CLEs) of the coupled systems. We find that the same scaling
relation exists for couplings between the drive and the ring. Further, we
have examined the robustness of the synchronous states against Gaussian white
noise and found that the synchronization error exhibits a power-law decay as a
function of the noise intensity indicating the existence of both noise-enhanced
and noise-induced synchronizations depending on the value of the coupling
strength . In addition, we have found that shows an
exponential decay as a function of the number of additional couplings. These
results are demonstrated using the paradigmatic models of R\"ossler and Lorenz
oscillators.Comment: Accepted for Publication in Physical Review
Are we teaching our students what they need to know about ageing? Results from the National Survey of Undergraduate Teaching in Ageing and Geriatric Medicine
Introduction - Learning about ageing and the appropriate management of older patients is important for all doctors. This survey set out to evaluate what medical undergraduates in the UK are taught about ageing and geriatric medicine and how this teaching is delivered.
Methods – An electronic questionnaire was developed and sent to the 28/31 UK medical schools which agreed to participate.
Results – Full responses were received from 17 schools. 8/21 learning objectives were recorded as taught, and none were examined, across every school surveyed. Elder abuse and terminology and classification of health were taught in only 8/17 and 2/17 schools respectively. Pressure ulcers were taught about in 14/17 schools but taught formally in only 7 of these and examined in only 9. With regard to bio- and socio- gerontology, only 9/17 schools reported teaching in social ageing, 7/17 in cellular ageing and 9/17 in the physiology of ageing.
Discussion – Even allowing for the suboptimal response rate, this study presents significant cause for concern with UK undergraduate education related to ageing. The failure to teach comprehensively on elder abuse and pressure sores, in particular, may be significantly to the detriment of older patients
Response of Microorganisms to Hot Crude Oil Spills on a Subarctic Taiga Soil
This study was conducted on the short-term effects of seasonal spills of hot Prudhoe Bay crude oil on microorganisms in a taiga soil in interior Alaska. Following a winter spill, the filamentous fungal populations were inhibited whereas the heterotrophic bacterial populations were stimulated. After a summer spill there was an initial depression of both the filamentous fungal and bacterial populations followed by a general enhancement. In both oil spill plots, yeasts; along with the denitrifying, proteolytic, oil-utilizing, and cellulose-utilizing microorganisms; were favorably affected by the oil. Soil respiration was also enhanced in the oiled plots. An extended period of study is required to fully evaluate the impact of oil on the soil microflora and the role of these microorganisms in recovery of oil-inundated areas in subarctic ecosystems
Matrix Quantization of Turbulence
Based on our recent work on Quantum Nambu Mechanics \cite{af2}, we provide
an explicit quantization of the Lorenz chaotic attractor through the
introduction of Non-commutative phase space coordinates as Hermitian matrices in . For the volume preserving part, they satisfy the
commutation relations induced by one of the two Nambu Hamiltonians, the second
one generating a unique time evolution. Dissipation is incorporated quantum
mechanically in a self-consistent way having the correct classical limit
without the introduction of external degrees of freedom. Due to its volume
phase space contraction it violates the quantum commutation relations. We
demonstrate that the Heisenberg-Nambu evolution equations for the Matrix Lorenz
system develop fast decoherence to N independent Lorenz attractors. On the
other hand there is a weak dissipation regime, where the quantum mechanical
properties of the volume preserving non-dissipative sector survive for long
times.Comment: 14 pages, Based on invited talks delivered at: Fifth Aegean Summer
School, "From Gravity to Thermal Gauge theories and the AdS/CFT
Correspondance", September 2009, Milos, Greece; the Intern. Conference on
Dynamics and Complexity, Thessaloniki, Greece, 12 July 2010; Workshop on
"AdS4/CFT3 and the Holographic States of Matter", Galileo Galilei Institute,
Firenze, Italy, 30 October 201
Comparison of alcogas aviation fuel with export aviation gasoline
Mixtures of gasoline and alcohol when used in internal combustion engines designed for gasoline have been found to possess the advantage of alcohol in withstanding high compression without "knock" while retaining advantages of gasoline with regard to starting characteristics. Test of such fuels for maximum power-producing ability and fuel economy at various rates of consumption are thus of practical importance, with especial reference to high-compression engine development. This report discusses the results of tests which compares the performance of alcogas with x gasoline (export grade) as a standard
Fractional Generalization of Gradient Systems
We consider a fractional generalization of gradient systems. We use
differential forms and exterior derivatives of fractional orders. Examples of
fractional gradient systems are considered. We describe the stationary states
of these systems.Comment: 11 pages, LaTe
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