1,933 research outputs found
Hmong Women in Leadership: Creating a Multicultural Identity While Preserving Traditions in the Modern Age
The life of a Hmong woman in America is dedicated to trying to find the perfect balance between professional achievements and cultural and familial expectations. This proves extremely challenging as there are occasions when professional and personal demands are in absolute contrast. This situation is even more prevalent in the life of a Hmong woman who endeavors to become a leader in society. The purpose of this phenomenological culture case study, whose data will be based upon a nine-month research project, is to examine how recognized Hmong women leaders have overcome the differences in value systems and have balanced the demands of Hmong culture while maintaining a successful career
Revisiting the Jurassic Geomagnetic Reversal recorded in the Lesotho Basalt (Southern Africa)
We carried out a detailed and continuous paleomagnetic sampling of the
reversed to normal geomagnetic transition recorded by some 60 consecutive flow
units near the base of the Lesotho Basalt (183  1 Ma). After
alternating field or thermal cleaning the directions of remanence are generally
well clustered within flow units. In contrast, the thermal instability of the
samples did not allow to obtain reliable paleointensity determinations. The
geomagnetic transition is incompletely recorded due to a gap in volcanic
activity attested both by eolian deposits and a large angular distance between
the field directions of the flows underlying or overlying these deposits. The
transition path is noticeably different from that reported in the pioneer work
of van Zijl et al. (1962). The most transitional Virtual Geomagnetic Poles are
observed after the volcanic hiatus. Once continents are replaced in their
relative position 180 Ma ago, the post-hiatus VGP cluster over Russia. However,
two successive rebounds from that cluster are found, with VGP reaching
repeatedly Eastern Asia coast. Thus, the VGP path is not narrowly constrained
in paleolongitude. The decrease in intensity of magnetization as the field
deviates from the normal or reversed direction suggests that the decrease in
field magnitude during the reversal reached 80-90%. We conclude that although
the reversal is of a dipole of much weaker moment than that which existed on
average during Cenozoic time, the characteristics of the reversing geodynamo
seem to be basically similar.Comment: Paper No GD124 submitted to Geophysical Journal International.
Received in original form 20/01/2003, accepted 09/04/200
Facilitating employer engagement through negotiated work based learning: A case study from the University of Chester
This report discusses the development of a work based learning framework at the University of Chester and identifies its key features, particulary in relation to employer engagagement
The Pulsation of Chi Cygni Imaged by Optical Interferometry; a Novel Technique to Derive Distance and Mass of Mira Stars
We present infrared interferometric imaging of the S-type Mira star Chi
Cygni. The object was observed at four different epochs in 2005-2006 with the
IOTA optical interferometer (H band). Images show up to 40% variation in the
stellar diameter, as well as significant changes in the limb darkening and
stellar inhomogeneities. Model fitting gave precise time-dependent values of
the stellar diameter, and reveals presence and displacement of a warm molecular
layer. The star radius, corrected for limb darkening, has a mean value of 12.1
mas and shows a 5.1mas amplitude pulsation. Minimum diameter was observed at
phase 0.94+/-0.01. Maximum temperature was observed several days later at phase
1.02+/-0.02. We also show that combining the angular acceleration of the
molecular layer with CO (Delta v = 3) radial velocity measurements yields a
5.9+/-1.5 mas parallax. The constant acceleration of the CO molecules -- during
80% of the pulsation cycle -- lead us to argument for a free-falling layer. The
acceleration is compatible with a gravitational field produced by a
2.1(+1.5/-0.7) solar mass star. This last value is in agreement with
fundamental mode pulsator models. We foresee increased development of
techniques consisting in combining radial velocity with interferometric angular
measurements, ultimately allowing total mapping of the speed, density, and
position of the diverse species in pulsation driven atmospheres.Comment: 36 pages, accepted in Ap
Pre-maximum spectro-imaging of the Mira star T Lep with AMBER/VLTI
Diffuse envelopes around Mira variables are among the most important sources
influencing the chemical evolution of galaxies. However they represent an
observational challenge because of their complex spectral features and their
rapid temporal variability. We constrained the exact brightness distribution of
the Mira star TLep with a model-independent analysis. We obtained single-epoch
interferometric observations with a dataset continuous in the spectral domain
(1.5-2.4mum) and in the spatial domain (baselines ranging from 11 to 96m). We
performed a model independent image reconstruction for each spectral bin using
the MIRA software. We completed the analysis by modeling the data with a simple
star+layer model inspired from the images. Reconstructed images confirm the
general picture of a central star partially obscured by the surrounding
molecular shell of changing opacity. At 1.7mum, the shell becomes optically
thin, with corresponding emission appearing as a ring circling the star. This
is the first direct evidence of the spherical morphology of the molecular
shell. Model fitting confirmed a spherical layer of constant size and changing
opacity over the wavelengths. Rough modeling points to a continuum opacity
within the shell, in addition to the CO and H2O features. Accordingly, it
appeared impossible to model the data by a photosphere alone in any of the
spectral bins.Comment: Accepted in A&
Pulsation of M-type Mira variables with moderately different mass: search for observable mass effects
Models of M-type Miras with masses of 1 and 1.2 , i.e.
with envelope masses of about 0.4 and 0.6 , have been
constructed, and a comparison has been made of their observable properties.
Geometric pulsation of continuum-forming layers is found to be little affected
by the mass difference. The influence of molecular contamination of
near-infrared continuum bandpasses upon interferometrically measured fit
diameters ranges from undetectable to quite significant. Some pulsation cycles
of the lower-mass model Mira show substantially stronger contamination than
that found in any cycle of the higher-mass star. Observations which sample
pulsation phase well and continuously are crucial for avoiding
misinterpretations, because the assignment of absolute pulsation phases is
inherently uncertain by at least 0.1 cycles, diameter changes may be strongly
phase-dependent, and cycle-to-cycle variations may be substantial. In accord
with expectations, we find that cycle-to-cycle variations that show up in light
curves and in near-continuum diameters tend to be larger and more common in the
low-mass models, leading to one possible way to discriminate mass. Two other
methods, based on high-precision measurements of the pulsation amplitude and on
derivation of pre-maximum effective temperatures from diameter measurements,
are also discussed. High-layer features that may be strongly affected by mass
are not well described by present dust-free models.Comment: Accepted for MNRAS, 8 Pages, 8 Figure
Culture optimization for the emergent zooplanktonic model organism Oikopleura dioica
The pan-global marine appendicularian, Oikopleura dioica, shows considerable promise as a candidate model organism for cross-disciplinary research ranging from chordate genetics and evolution to molecular ecology research. This urochordate, has a simplified anatomical organization, remains transparent throughout an exceptionally short life cycle of less than 1 week and exhibits high fecundity. At 70 Mb, the compact, sequenced genome ranks among the smallest known metazoan genomes, with both gene regulatory and intronic regions highly reduced in size. The organism occupies an important trophic role in marine ecosystems and is a significant contributor to global vertical carbon flux. Among the short list of bona fide biological model organisms, all share the property that they are amenable to long-term maintenance in laboratory cultures. Here, we tested diet regimes, spawn densities and dilutions and seawater treatment, leading to optimization of a detailed culture protocol that permits sustainable long-term maintenance of O. dioica, allowing continuous, uninterrupted production of source material for experimentation. The culture protocol can be quickly adapted in both coastal and inland laboratories and should promote rapid development of the many original research perspectives the animal offers
Influence of lasers propagation delay on the sensitivity of atom interferometers
In atom interferometers based on two photon transitions, the delay induced by
the difference of the laser beams paths makes the interferometer sensitive to
the fluctuations of the frequency of the lasers. We first study, in the general
case, how the laser frequency noise affects the performance of the
interferometer measurement. Our calculations are compared with the measurements
performed on our cold atom gravimeter based on stimulated Raman transitions. We
finally extend this study to the case of cold atom gradiometers.Comment: 17 pages, 6 figure
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