14,117 research outputs found
Dispersion Relations for Bernstein Waves in a Relativistic Pair Plasma
A fully relativistic treatment of Bernstein waves in an electron-positron
pair plasma has remained too formidable a task owing to the very complex nature
of the problem. In this article, we perform contour integration of the
dielectric response function and numerically compute the dispersion curves for
a uniform, magnetized, relativistic electron-positron pair plasma. The behavior
of the dispersion solution for several cases with different plasma temperatures
is highlighted. In particular, we find two wave modes that exist only for large
wavelengths and frequencies similar to the cyclotron frequency in a moderately
relativistic pair plasma. The results presented here have important
implications for the study of those objects where a hot magnetized
electron-positron plasma plays a fundamental role in generating the observed
radiation.Comment: 8 pages, 8 figures, Accepted for publication by Phys. Rev. E with
minor change
Roles of Education and IQ in Cognitive Reserve in Parkinson's Disease-Mild Cognitive Impairment.
Background/aimsThe role of cognitive reserve in Parkinson's disease (PD)-mild cognitive impairment (MCI) is incompletely understood.MethodsThe relationships between PD-MCI, years of education, and estimated premorbid IQ were examined in 119 consecutive non-demented PD patients using logistic regression models.ResultsHigher education and IQ were associated with reduced odds of PD-MCI in univariate analysis. In multivariable analysis, a higher IQ was associated with a significantly decreased odds of PD-MCI, but education was not.ConclusionThe association of higher IQ and decreased odds of PD-MCI supports a role for cognitive reserve in PD, but further studies are needed to clarify the interaction of IQ and education and the impact of other contributors such as employment and hobbies
Report of the Horse Mackerel Exchange and Workshop 2006
Following a recommendation from PGCCDBS, a workshop on age calibration of horse mackerel was carried out. The workshop was preceded by an exchange. The objectives were: to improve the quality of horse mackerel readings by international calibration. In particular, attempt to resolve the observed differences between countries. Estimate the accuracy and precision of the age readings before and after the intercalibration. Take into account differences between areas and methods. Training of new horse mackerel readers
Ion-Acoustic Solitons in Bi-Ion Dusty Plasma
The propagation of ion-acoustic solitons in a warm dusty plasma containing
two ion species is investigated theoretically. Using an approach based on the
Korteveg-de-Vries equation, it is shown that the critical value of the negative
ion density that separates the domains of existence of compressi- on and
rarefaction solitons depends continuously on the dust density. A modified
Korteveg-de Vries equation for the critical density is derived in the higher
order of the expansion in the small parameter. It is found that the nonlinear
coefficient of this equation is positive for any values of the dust density and
the masses of positive and negative ions. For the case where the negative ion
density is close to its critical value, a soliton solution is found that takes
into account both the quadratic and cubic nonlinearities. The propagation of a
solitary wave of arbitrary amplitude is investigated by the quasi-potential
method. It is shown that the range of the dust densities around the critical
value within which solitary waves with positive and negative potentials can
exist simultaneously is relatively wide.Comment: 17 pages, 5 figure
An exploratory study looking at the relationship marketing techniques used in the music festival industry
There are current issues and trends in the music festival
market, which may affect the success of an event, and market saturation
is at the forefront of these issues. Previous literature, maintaining
the need for a marketing approach to festivals, identifi es the need
for maintaining strong stakeholder relationships in order to succeed
in a business environment; attention has been focused to the theory
of relationship marketing (RM) because of the recognition that this
practice is complementary to the marketing of festivals. The very nature
of the music festival as an annual, usually, 4-day event means that
effective marketing is needed to keep connections with the consumer
throughout the year. This article focuses on the RM techniques
utilised within the music festival industry from the viewpoint of the
festival organiser in an attempt to establish how festival organisations
value and monitor organisational relationships. This article explores
the extent to which these relationships are valued and managed;
furthermore, the variations between these intricate relationships
are considered by focusing on those held with the organisation ’ s
consumers and sponsors, the results of which have provided the
ability to establish the importance and relevance of RM to the industry
and further identify the marketing communication methods employed
to establish and maintain such relationships. In-depth, convergent
interviews have been conducted with a segment of music festival
organisers from a range of events. The results have been integrated
with the study of current literature to best exemplify these issues. It
has been established that RM has a strong role in today ’ s commercial
and independent music festival industry; technological advances are
enabling the organiser to support online relationships further and
increase consumer loyalty. There is a need to expand the research
further because of the complexity of organisational relationships and
the varying categories of festivals
Lunar navigation study, sections 1 through 7 Final report, Jun. 1964 - May 1965
Lunar navigation analysis using passive nongyro, inertial navigation, and radio frequency technolog
Lunar navigation study, summary volume Final report, Jun. 1964 - May 1965
Lunar surface navigation and guidance study to implement lunar surface vehicle exploration mission
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