2,123 research outputs found
Quantum Limits of Measurements Induced by Multiplicative Conservation Laws: Extension of the Wigner-Araki-Yanase Theorem
The Wigner-Araki-Yanase (WAY) theorem shows that additive conservation laws
limit the accuracy of measurements. Recently, various quantitative expressions
have been found for quantum limits on measurements induced by additive
conservation laws, and have been applied to the study of fundamental limits on
quantum information processing. Here, we investigate generalizations of the WAY
theorem to multiplicative conservation laws. The WAY theorem is extended to
show that an observable not commuting with the modulus of, or equivalently the
square of, a multiplicatively conserved quantity cannot be precisely measured.
We also obtain a lower bound for the mean-square noise of a measurement in the
presence of a multiplicatively conserved quantity. To overcome this noise it is
necessary to make large the coefficient of variation (the so-called relative
fluctuation), instead of the variance as is the case for additive conservation
laws, of the conserved quantity in the apparatus.Comment: 8 pages, REVTEX; typo added, to appear in PR
Models of hydrothermal circulation within 106 Ma seafloor : constraints on the vigor of fluid circulation and crustal properties, below the Madeira Abyssal Plain
Author Posting. Β© American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 6 (2005): Q11001, doi:10.1029/2005GC001013.Heat flow measurements colocated with seismic data across 106 Ma seafloor of the Madeira Abyssal Plain (MAP) reveal variations in seafloor heat flow of Β±10β20% that are positively correlated with basement relief buried below thick sediments. Conductive finite element models of sediments and upper basement using reasonable thermal properties are capable of generating the observed positive correlation between basement relief and seafloor heat flow, but with variability of just Β±4β8%. Conductive simulations using a high Nusselt number (Nu) proxy for vigorous local convection suggest that Nu = 2β10 within the upper 600β100 m of basement, respectively, is sufficient to achieve a reasonable match to observations. These Nu values are much lower than those inferred on younger ridge flanks where greater thermal homogeneity is achieved in upper basement. Fully coupled simulations suggest that permeability below the MAP is on the order of 10β12β10β10 m2 within the upper 300β600 m of basement. This permeability range is broadly consistent with values determined by single-hole experiments and from modeling studies at other (mostly younger) sites. We infer that the reduction in basement permeability with age that is thought to occur within younger seafloor may slow considerably within older seafloor, helping hydrothermal convection to continue as plates age.Funding in support of this work was provided by the U.S. National Science Foundation (OCE-0001892), the U.S. Science Support Program for IODP (T301A7), and the Institute for Geophysics and Planetary Physics/Los Alamos National Laboratory (1317)
Π’ΡΠ°Π½ΡΠΏΠΎΡΡΠ½Π°Ρ Π»ΠΎΠ³ΠΈΡΡΠΈΠΊΠ°: ΠΏΡΠΎΠ±Π»Π΅ΠΌΡ ΠΈ ΠΏΠ΅ΡΡΠΏΠ΅ΠΊΡΠΈΠ²Ρ ΡΠ°Π·Π²ΠΈΡΠΈΡ Π² ΡΠ°ΠΌΠΎΠΆΠ΅Π½Π½ΠΎΠΌ Π΄Π΅Π»Π΅
ΠΡΠΏΡΡΠΊΠ½Π°Ρ ΠΊΠ²Π°Π»ΠΈΡΠΈΠΊΠ°ΡΠΈΠΎΠ½Π½Π°Ρ ΡΠ°Π±ΠΎΡΠ° ΠΏΠΎΡΠ²ΡΡΠ΅Π½Π° ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΡΡΠ°Π½ΡΠΏΠΎΡΡΠ½ΠΎΠΉ Π»ΠΎΠ³ΠΈΡΡΠΈΠΊΠ΅ Π² ΡΠ°ΠΌΠΎΠΆΠ΅Π½Π½ΠΎΠΌ Π΄Π΅Π»Π΅. Π¦Π΅Π»ΡΡ Π΄Π°Π½Π½ΠΎΠΉ ΡΠ°Π±ΠΎΡΡ ΡΠ²Π»ΡΠ΅ΡΡΡ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ½ΡΠΉ Π°Π½Π°Π»ΠΈΠ· ΡΠ°ΠΊΡΠΎΡΠΎΠ², ΠΌΠ΅Ρ
Π°Π½ΠΈΠ·ΠΌΠΎΠ² ΠΈ ΠΏΡΠΎΠ±Π»Π΅ΠΌ ΡΡΠ°Π½ΡΡΠΎΡΠΌΠ°ΡΠΈΠΈ ΡΠ°ΠΌΠΎΠΆΠ΅Π½Π½ΠΎΠΉ Π»ΠΎΠ³ΠΈΡΡΠΈΠΊΠΈ Π² Π³Π»ΠΎΠ±Π°Π»ΡΠ½ΠΎΠΉ ΡΠΎΡΠ³ΠΎΠ²ΠΎΠΉ ΡΠΈΡΡΠ΅ΠΌΠ΅ ΠΈ ΠΎΠ±ΠΎΡΠ½ΠΎΠ²Π°Π½ΠΈΠ΅ Π½Π°ΠΏΡΠ°Π²Π»Π΅Π½ΠΈΠΉ Π°Π΄Π°ΠΏΡΠ°ΡΠΈΠΈ ΡΠ°ΠΌΠΎΠΆΠ΅Π½Π½ΠΎΠΉ Π»ΠΎΠ³ΠΈΡΡΠΈΠΊΠΈ Π ΠΎΡΡΠΈΠΈ Π² ΡΡΠ»ΠΎΠ²ΠΈΡΡ
Π»ΠΈΠ±Π΅ΡΠ°Π»ΠΈΠ·Π°ΡΠΈΠΈ ΠΌΠ΅ΠΆΠ΄ΡΠ½Π°ΡΠΎΠ΄Π½ΠΎΠΉ ΡΠΎΡΠ³ΠΎΠ²Π»ΠΈ. ΠΠ°Π΄Π°ΡΠΈ: β’ΠΠΎΠ½ΡΡΠΈΠ΅, Π²ΠΈΠ΄Ρ, ΡΡΠ½ΠΊΡΠΈΠΈ Π»ΠΎΠ³ΠΈΡΡΠΈΠΊΠΈ β’ΠΠ°Π΄Π°ΡΠΈ ΡΡΠ°Π½ΡΠΏΠΎΡΡΠ½ΠΎΠΉ Π»ΠΎΠ³ΠΈΡΡΠΈΠΊΠΈ β’Π‘ΡΡΠ½ΠΎΡΡΡ ΡΠ°ΠΌΠΎΠΆΠ΅Π½Π½ΠΎΠΉ Π»ΠΎΠ³ΠΈΡΡΠΈΠΊΠΈ β’ΠΡΠΎΠ±Π»Π΅ΠΌΡ ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΈΡ ΡΠ°ΠΌΠΎΠΆΠ΅Π½Π½ΠΎΠΉ Π»ΠΎΠ³ΠΈΡΡΠΈΠΊΠΈ β’ΠΠ»ΡΡΠ΅Π²ΡΠ΅ ΠΏΡΠΎΠ±Π»Π΅ΠΌΡ ΡΠ°ΠΌΠΎΠΆΠ΅Π½Π½ΠΎΠΉ Π»ΠΎΠ³ΠΈΡΡΠΈΠΊΠΈ β’ΠΠ΅ΡΡΠΏΠ΅ΠΊΡΠΈΠ²Ρ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΡΠ°ΠΌΠΎΠΆΠ΅Π½Π½ΠΎΠΉ Π»ΠΎΠ³ΠΈΡΡΠΈΠΊΠΈ.
ΠΠ±ΡΠ΅ΠΊΡΠΎΠΌ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΡΠ²Π»ΡΠ΅ΡΡΡ ΠΏΡΠΎΡΠ΅ΡΡ ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΈ ΡΠ΅Π°Π»ΠΈΠ·Π°ΡΠΈΠΈ ΡΠ°ΠΌΠΎΠΆΠ΅Π½Π½ΠΎΠΉ Π»ΠΎΠ³ΠΈΡΡΠΈΠΊΠΈ Π² Π³Π»ΠΎΠ±Π°Π»ΡΠ½ΠΎΠΉ ΡΠΎΡΠ³ΠΎΠ²ΠΎΠΉ ΡΠΈΡΡΠ΅ΠΌΠ΅.The final qualifying work is devoted to the study of transport logistics in the customs business.
The purpose of this work is a comprehensive analysis of the factors, mechanisms and problems of the transformation of customs logistics in the global trading system and the rationale for adapting the customs logistics of Russia in the context of the liberalization of international trade
Dynamics of Magnetic Flux Elements in the Solar Photosphere
The interaction of magnetic fields and convection is investigated in the
context of the coronal heating problem. We study the motions of photospheric
magnetic elements using filtergrams obtained at the Swedish Vacuum Solar
Telescope at La Palma. We use potential-field modeling to extrapolate the
magnetic and velocity fields to larger height. We find that the velocity in the
chromosphere can be locally enhanced at the separatrix surfaces between
neighboring flux tubes. The predicted velocities are several km/s,
significantly larger than those of the photospheric flux tubes, which may have
important implications for coronal heating. sComment: submitted to ApJ, 21 pages, 10 figure
A pilot Internet "Value of Health" Panel: recruitment, participation and compliance
Objectives
To pilot using a panel of members of the public to provide preference data via the Internet
Methods
A stratified random sample of members of the general public was recruited and familiarised with the standard gamble procedure using an Internet based tool. Health states were perdiodically presented in "sets" corresponding to different conditions, during the study. The following were described: Recruitment (proportion of people approached who were trained); Participation (a) the proportion of people trained who provided any preferences and (b) the proportion of panel members who contributed to each "set" of values; and Compliance (the proportion, per participant, of preference tasks which were completed). The influence of covariates on these outcomes was investigated using univariate and multivariate analyses.
Results
A panel of 112 people was recruited. 23% of those approached (n = 5,320) responded to the invitation, and 24% of respondents (n = 1,215) were willing to participate (net = 5.5%). However, eventual recruitment rates, following training, were low (2.1% of those approached). Recruitment from areas of high socioeconomic deprivation and among ethnic minority communities was low. Eighteen sets of health state descriptions were considered over 14 months. 74% of panel members carried out at least one valuation task. People from areas of higher socioeconomic deprivation and unmarried people were less likely to participate. An average of 41% of panel members expressed preferences on each set of descriptions. Compliance ranged from 3% to 100%.
Conclusion
It is feasible to establish a panel of members of the general public to express preferences on a wide range of health state descriptions using the Internet, although differential recruitment and attrition are important challenges. Particular attention to recruitment and retention in areas of high socioeconomic deprivation and among ethnic minority communities is necessary. Nevertheless, the panel approach to preference measurement using the Internet offers the potential to provide specific utility data in a responsive manner for use in economic evaluations and to address some of the outstanding methodological uncertainties in this field
In-medium nucleon-nucleon potentials in configuration space
Based on the thermodynamic Green function approach two-nucleon correlations
in nuclear matter at finite temperatures are revisited. To this end, we derive
phase equivalent effective -space potentials that include the effect of the
Pauli blocking at a given temperature and density. These potentials enter into
a Schr\"odinger equation that is the -space representation of the
Galitskii-Feynman equation for two nucleons. We explore the analytical
structure of the equation in the complex -plane by means of Jost functions.
We find that despite the Mott effect the correlation with deuteron quantum
numbers are manifested as antibound states, i.e., as zeros of the Jost function
on the negative imaginary axis of the complex momentum space. The analysis
presented here is also suited for Coulombic systems.Comment: 6 pages, 1 table, 4 figure
High-Frequency Oscillations in a Solar Active Region observed with the Rapid Dual Imager
High-cadence, synchronized, multiwavelength optical observations of a solar
active region (NOAA 10794) are presented. The data were obtained with the Dunn
Solar Telescope at the National Solar Observatory/Sacramento Peak using a newly
developed camera system : the Rapid Dual Imager. Wavelet analysis is undertaken
to search for intensity related oscillatory signatures, and periodicities
ranging from 20 to 370 s are found with significance levels exceeding 95%.
Observations in the H-alpha blue wing show more penumbral oscillatory phenomena
when compared to simultaneous G-band observations. The H-alpha oscillations are
interpreted as the signatures of plasma motions with a mean velocity of 20
km/s. The strong oscillatory power over H-alpha blue-wing and G-band penumbral
bright grains is an indication of the Evershed flow with frequencies higher
than previously reported.Comment: 9 pages, 9 figure
Radiation-induced oscillatory magnetoresistance as a sensitive probe of the zero-field spin splitting in high mobility GaAs/AlGaAs devices
We suggest an approach for characterizing the zero-field spin splitting of
high mobility two-dimensional electron systems, when beats are not readily
observable in the Shubnikov-de Haas effect. The zero-field spin splitting and
the effective magnetic field seen in the reference frame of the electron is
evaluated from a quantitative study of beats observed in radiation-induced
magnetoresistance oscillations.Comment: 4 pages, 4 color figure
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