4,789 research outputs found
An observation of LHR noise with banded structure by the sounding rocket S29 Barium-GEOS
The measurement of electrostatic and obviously locally produced noise near the lower hybrid frequency made by the sounding rocket S29 Barium-GEOS is reported. The noise is strongly related to the spin of the rocket and reaches well below the local lower hybrid resonance frequency. Above the altitude of 300 km the noise shows banded structure roughly organized by the hydrogen cyclotron frequency. Simultaneously with the banded structure, a signal near the hydrogen cyclotron frequency is detected. This signal is also spin related. The characteristics of the noise suggest that it is locally generated by the rocket payload disturbing the plasma. If this interpretation is correct we expect plasma wave experiments on other spacecrafts, e.g., the space shuttle to observe similar phenomena
Conclusions from the symposium: Two decades of ART: success through research
Two decades of ART research has served as the catalyst for a new way of thinking about oral health care. It is now necessary to build on the success of ART research by educating existing and future oral health professionals and health decision makers about the benefits of the ART approach. It is also important to build upon the sound research base that already exists on ART even though enough is known about ART to consider it is a reliable and quality approach to control caries. While oral health promotion through prevention remains the essential foundation of oral health, the ART approach is an important corner stone in the building of global oral health
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Replicating the Family: The Biopolitics of Involvement Discourses Concerning Relatives in Nursing Home Institutions
The aim of this study was to describe the biopolitics of involvement discourses articulated by nursing staff concerning relatives in nursing home institutions, using a Foucault-inspired discourse analytical approach. Previous research has described how relatives have not been involved in nursing homes on their own terms. This is partly due to a lack of communication and knowledge, but it is also a consequence of an unclear organizational structure. Results from a discourse analysis of six focus group interviews with nursing staff show that the “involvement discourse” in nursing homes can be described as a “new” vs “old” family rhetoric. This rhetoric can be said to uphold, legitimize and provide different subject positions for both nursing staff and relatives concerning the conditions for involvement in nursing homes. As part of a “project of possibility” in elderly care, it may be possible to adopt a critical pedagogical approach among nursing staff in order to educate, strengthen and support them in reflecting on their professional norming and how it conditions the involvement of relatives
Discovery of an Unbound Hyper-Velocity Star in the Milky Way Halo
We have discovered a star, SDSS J090745.0+024507, leaving the Galaxy with a
heliocentric radial velocity of +853+-12 km/s, the largest velocity ever
observed in the Milky Way halo. The star is either a hot blue horizontal branch
star or a B9 main sequence star with a heliocentric distance ~55 kpc. Corrected
for the solar reflex motion and to the local standard of rest, the Galactic
rest-frame velocity is +709 km/s.
Because its radial velocity vector points 173.8 deg from the Galactic center,
we suggest that this star is the first example of a hyper-velocity star ejected
from the Galactic center as predicted by Hills and later discussed by Yu &
Tremaine. The star has [Fe/H]~0, consistent with a Galactic center origin, and
a travel time of <80 Myr from the Galactic center, consistent with its stellar
lifetime. If the star is indeed traveling from the Galactic center, it should
have a proper motion of 0.3 mas/yr observable with GAIA. Identifying additional
hyper-velocity stars throughout the halo will constrain the production rate
history of hyper-velocity stars at the Galactic center.Comment: 4 pages, submitted to ApJ Letter
Cutting edges at random in large recursive trees
We comment on old and new results related to the destruction of a random
recursive tree (RRT), in which its edges are cut one after the other in a
uniform random order. In particular, we study the number of steps needed to
isolate or disconnect certain distinguished vertices when the size of the tree
tends to infinity. New probabilistic explanations are given in terms of the
so-called cut-tree and the tree of component sizes, which both encode different
aspects of the destruction process. Finally, we establish the connection to
Bernoulli bond percolation on large RRT's and present recent results on the
cluster sizes in the supercritical regime.Comment: 29 pages, 3 figure
Revised physical elements of the astrophysically important O9.5+O9.5V eclipsing binary system Y Cyg
Thanks to its long and rich observational history and rapid apsidal motion,
the massive eclipsing binary Y Cyg represents one of the cornestones to
critical tests of stellar evolution theory for massive stars. Yet, the
determination of the basic physical properties is less accurate than it could
be given the existing number of spectral and photometric observations. Our goal
is to analyze all these data simultaneously with the new dedicated series of
our own spectral and photometric observations from observatories widely
separated in longitude. We obtained new series of UBV observations at three
observatories separated in local time to obtain complete light curves of Y Cyg
for its orbital period close to 3 days. This new photometry was reduced and
carefully transformed to the standard UBV system using the HEC22 program. We
also obtained new series of red spectra secured at two observatories and
re-analyzed earlier obtained blue electronic spectra. Our analyses provide the
most accurate so far published value of the apsidal period of 47.805 +/- 0.030
yrs and the following physical elements: M1=17.72+/-0.35$ Msun, M2=17.73+/-0.30
Msun, R1=5.785+/-0.091 Rsun, and R2=5.816+/-0.063 Rsun. The disentangling thus
resulted in the masses, which are somewhat higher than all previous
determinations and virtually the same for both stars, while the light curve
implies a slighly higher radius and luminosity for star 2. The above empirical
values imply the logarithm of the internal structure constant log k2 = -1.937.
A comparison with Claret's stellar interior models implies an age close to 2
millions yrs for both stars. The claimed accuracy of modern element
determination of 1-2 per cent seems still a bit too optimistic and obtaining
new high-dispersion and high-resolution spectra is desirable.Comment: 13 pages; accepted for publication in Astronomy and Astrophysic
Defects and boundary layers in non-Euclidean plates
We investigate the behavior of non-Euclidean plates with constant negative
Gaussian curvature using the F\"oppl-von K\'arm\'an reduced theory of
elasticity. Motivated by recent experimental results, we focus on annuli with a
periodic profile. We prove rigorous upper and lower bounds for the elastic
energy that scales like the thickness squared. In particular we show that are
only two types of global minimizers -- deformations that remain flat and saddle
shaped deformations with isolated regions of stretching near the edge of the
annulus. We also show that there exist local minimizers with a periodic profile
that have additional boundary layers near their lines of inflection. These
additional boundary layers are a new phenomenon in thin elastic sheets and are
necessary to regularize jump discontinuities in the azimuthal curvature across
lines of inflection. We rigorously derive scaling laws for the width of these
boundary layers as a function of the thickness of the sheet
P04-46. Broadly cross-neutralizing activity in plasma of HIV-1 and HIV-2 infected individuals
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