2,053 research outputs found
Wilbur Norman Christiansen 1913-2007
W. N. ('Chris') Christiansen was an innovative and influential radio
astronomy pioneer. The hallmarks of his long and distinguished career in
science and engineering, spanning almost five decades, were his inventiveness
and his commitment to, and success with, large-scale projects. These projects
were the outcome of his innovative skill as physicist and engineer. Paralleling
this was his equal commitment to forging strong international links and
friendships, leading to his election as Vice-President of the International
Astronomical Union for the years 1964 to 1970, as President of the
International Union of Radio Science, URSI, from 1978 to 1981, and subsequently
as Honorary Life President in 1984, and as Foreign Secretary of the Australian
Academy of Science from 1981 to 1985. Major subsequent developments in radio
astronomy and wireless communications on the global scene stand as a legacy to
Chris's approach to his work and to the development of those who worked with
him.Comment: 16 pages, 4 figure
Bernard Yarnton Mills 1920-2011
Bernie Mills is remembered globally as an influential pioneer in the evolving
field of radio astronomy. His contributions with the 'Mills Cross' at the CSIRO
Division of Radiophysics and later at the University of Sydney's School of
Physics and the development of the Molonglo Observatory Synthesis Telescope
(MOST) were widely recognised as astronomy evolved in the years 1948-1985 and
radio astronomy changed the viewpoint of the astronomer as a host of new
objects were discovered
The Need for Diversity in the Tourism and Hospitality Industry
Examined at a macro level, there are several key factors that are likely to influence the tourism and hospitality industry. The first factor is the changing face of the American population. A second factor is the rate of growth of the tourism industry. A third, and very important factor is the extent to which the industry embraces diversity. There is a need for industries to reach out to a diverse group of customers and employees. The need for cross-cultural responsiveness and the adoption of training models is apparent. This paper examines population and travel industry data-trends as a corner stone for embracing diversity as both a moral and global or national economic and social reality. Among the issues to be discussed are the racial and ethnic trends in the travel industry workforce, racial and ethnic trends in the ravel market, the content of globalization, and the adaptability of multicultural models used in disciplines such as counseling to the tourism and hospitality industry
Vibration in Planetary Gear Systems with Unequal Planet Stiffnesses
An algorithm suitable for a minicomputer was developed for finding the natural frequencies and mode shapes of a planetary gear system which has unequal stiffnesses between the Sun/planet and planet/ring gear meshes. Mode shapes are represented in the form of graphical computer output that illustrates the lateral and rotational motion of the three coaxial gears and the planet gears. This procedure permits the analysis of gear trains utilizing nonuniform mesh conditions and user specified masses, stiffnesses, and boundary conditions. Numerical integration of the equations of motion for planetary gear systems indicates that this algorithm offers an efficient means of predicting operating speeds which may result in high dynamic tooth loads
Integrating genealogical and dynamical modelling to infer escape and reversion rates in HIV epitopes
The rates of escape and reversion in response to selection pressure arising
from the host immune system, notably the cytotoxic T-lymphocyte (CTL) response,
are key factors determining the evolution of HIV. Existing methods for
estimating these parameters from cross-sectional population data using ordinary
differential equations (ODE) ignore information about the genealogy of sampled
HIV sequences, which has the potential to cause systematic bias and
over-estimate certainty. Here, we describe an integrated approach, validated
through extensive simulations, which combines genealogical inference and
epidemiological modelling, to estimate rates of CTL escape and reversion in HIV
epitopes. We show that there is substantial uncertainty about rates of viral
escape and reversion from cross-sectional data, which arises from the inherent
stochasticity in the evolutionary process. By application to empirical data, we
find that point estimates of rates from a previously published ODE model and
the integrated approach presented here are often similar, but can also differ
several-fold depending on the structure of the genealogy. The model-based
approach we apply provides a framework for the statistical analysis of escape
and reversion in population data and highlights the need for longitudinal and
denser cross-sectional sampling to enable accurate estimate of these key
parameters
Stentless mitral valves
Numeración errónea en el original
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