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The petrology of fine-grained micrometeorites: Evidence for the diversity of primitive asteroids
We report the discovery by analytical TEM of serpentine and phases interpreted as dehydroxylates of serpentine in ultramicrotomed sections of a number of fine-grained Antarctic micrometeorites
Solar-Cycle Characteristics Examined in Separate Hemispheres: Phase, Gnevyshev Gap, and Length of Minimum
Research results from solar-dynamo models show the northern and southern
hemispheres may evolve separately throughout the solar cycle. The observed
phase lag between the hemispheres provides information regarding the strength
of hemispheric coupling. Using hemispheric sunspot-area and sunspot-number data
from Cycles 12 - 23, we determine how out of phase the separate hemispheres are
during the rising, maximum, and declining period of each solar cycle.
Hemispheric phase differences range from 0 - 11, 0 - 14, and 2 - 19 months for
the rising, maximum, and declining periods, respectively. The phases appear
randomly distributed between zero months (in phase) and half of the rise (or
decline) time of the solar cycle. An analysis of the Gnevyshev gap is conducted
to determine if the double-peak is caused by the averaging of two hemispheres
that are out of phase. We confirm previous findings that the Gnevyshev gap is a
phenomenon that occurs in the separate hemispheres and is not due to a
superposition of sunspot indices from hemispheres slightly out of phase. Cross
hemispheric coupling could be strongest at solar minimum, when there are large
quantities of magnetic flux at the Equator. We search for a correlation between
the hemispheric phase difference near the end of the solar cycle and the length
of solar-cycle minimum, but found none. Because magnetic flux diffusion across
the Equator is a mechanism by which the hemispheres couple, we measured the
magnetic flux crossing the Equator by examining magnetograms for Solar Cycles
21 - 23. We find, on average, a surplus of northern hemisphere magnetic flux
crossing during the mid-declining phase of each solar cycle. However, we find
no correlation between magnitude of magnetic flux crossing the Equator, length
of solar minima, and phase lag between the hemispheres.Comment: 15 pages, 7 figure
Occupational therapists’ views of using a virtual reality interior design application within the pre-discharge home visit process
This article has been made available through the Brunel Open Access Publishing Fund.Background: A key role of Occupational Therapists (OTs) is to carry out pre-discharge home visits (PHV) and propose appropriate adaptations to the home environment, to enable patients to function independently after hospital-home discharge. However, research shows that more than 50% of specialist equipment installed as part of home adaptations is not used by patients. A key reason for this is that decisions about home adaptations are often made without adequate collaboration and consultation with the patient. Consequently, there is an urgent need to seek out new and innovative uses of technology to facilitate patient/practitioner collaboration, engagement and shared decision making in the PHV process. Virtual reality interior design applications (VRIDAs) primarily allow users to simulate the home environment and visualise changes prior to implementing them. Customised VRIDAs, which also model specialist occupational therapy equipment, could become a valuable tool to facilitate improved patient/practitioner collaboration if developed effectively and integrated into the PHV process. Objective: To explore the perceptions of occupational therapists with regards to using VRIDAs as an assistive tool within the PHV process. Methods: Task-oriented interactive usability sessions, utilising the think-aloud protocol and subsequent semi-structured interviews were carried out with seven Occupational Therapists who possessed significant experience across a range of clinical settings. Template analysis was carried out on the think-aloud and interview data. Analysis was both inductive and driven by theory, centring around the parameters that impact upon the acceptance, adoption and use of this technology in practice as indicated by the Technology Acceptance Model (TAM). Results: OTs’ perceptions were identified relating to three core themes: (1) perceived usefulness (PU), (2) perceived ease of use (PEoU), and (3) actual use (AU). Regarding PU, OTs believed VRIDAs had promising potential to increase understanding, enrich communications and patient involvement, and improved patient/practitioner shared understanding. However, it was unlikely that VRIDAs would be suitable for use with cognitively impaired patients. For PEoU, all OTs were able to use the software and complete the tasks successfully, however, participants noted numerous specialist equipment items that could be added to the furniture library. AU perceptions were positive regarding use of the application across a range of clinical settings including children/young adults, long-term conditions, neurology, older adults, and social services. However, some “fine tuning” may be necessary if the application is to be optimally used in practice. Conclusions: Participants perceived the use of VRIDAs in practice would enhance levels of patient/practitioner collaboration and provide a much needed mechanism via which patients are empowered to become more equal partners in decisions made about their care. Further research is needed to explore patient perceptions of VRIDAs, to make necessary customisations accordingly, and to explore deployment of the application in a collaborative patient/practitioner-based context
C^2/Z_n Fractional branes and Monodromy
We construct geometric representatives for the C^2/Z_n fractional branes in
terms of branes wrapping certain exceptional cycles of the resolution. In the
process we use large radius and conifold-type monodromies, and also check some
of the orbifold quantum symmetries. We find the explicit Seiberg-duality which
connects our fractional branes to the ones given by the McKay correspondence.
We also comment on the Harvey-Moore BPS algebras.Comment: 34 pages, v1 identical to v2, v3: typos fixed, discussion of
Harvey-Moore BPS algebras update
Special Lagrangian cones with higher genus links
For every odd natural number g=2d+1 we prove the existence of a countably
infinite family of special Lagrangian cones in C^3 over a closed Riemann
surface of genus g, using a geometric PDE gluing method.Comment: 48 page
Nuclear Octupole Correlations and the Enhancement of Atomic Time-Reversal Violation
We examine the time-reversal-violating nuclear ``Schiff moment'' that induces
electric dipole moments in atoms. After presenting a self-contained derivation
of the form of the Schiff operator, we show that the distribution of Schiff
strength, an important ingredient in the ground-state Schiff moment, is very
different from the electric-dipole-strength distribution, with the Schiff
moment receiving no strength from the giant dipole resonance in the
Goldhaber-Teller model. We then present shell-model calculations in light
nuclei that confirm the negligible role of the dipole resonance and show the
Schiff strength to be strongly correlated with low-lying octupole strength.
Next, we turn to heavy nuclei, examining recent arguments for the strong
enhancement of Schiff moments in octupole-deformed nuclei over that of 199Hg,
for example. We concur that there is a significant enhancement while pointing
to effects neglected in previous work (both in the octupole-deformed nuclides
and 199Hg) that may reduce it somewhat, and emphasizing the need for
microscopic calculations to resolve the issue. Finally, we show that static
octupole deformation is not essential for the development of collective Schiff
moments; nuclei with strong octupole vibrations have them as well, and some
could be exploited by experiment.Comment: 25 pages, 4 figures embedded in tex
A burst with double radio spectrum observed up to 212 GHz
We study a solar flare that occurred on September 10, 2002, in active region
NOAA 10105 starting around 14:52 UT and lasting approximately 5 minutes in the
radio range. The event was classified as M2.9 in X-rays and 1N in H\alpha.
Solar Submillimeter Telescope observations, in addition to microwave data give
us a good spectral coverage between 1.415 and 212 GHz. We combine these data
with ultraviolet images, hard and soft X-rays observations and full-disk
magnetograms. Images obtained from Ramaty High Energy Solar Spectroscopic
Imaging data are used to identify the locations of X-ray sources at different
energies and to determine the X-ray spectrum, while ultra violet images allow
us to characterize the coronal flaring region. The magnetic field evolution of
the active region is analyzed using Michelson Doppler Imager magnetograms. The
burst is detected at all available radio-frequencies. X-ray images (between 12
keV and 300 keV) reveal two compact sources and 212 GHz data, used to estimate
the radio source position, show a single compact source displaced by 25" from
one of the hard X-ray footpoints. We model the radio spectra using two
homogeneous sources, and combine this analysis with that of hard X-rays to
understand the dynamics of the particles. Relativistic particles, observed at
radio wavelengths above 50 GHz, have an electron index evolving with the
typical soft-hard-soft behaviour.Comment: Submitted to Solar Physics, 20 pages, 8 fugure
Solar Intranetwork Magnetic Elements: bipolar flux appearance
The current study aims to quantify characteristic features of bipolar flux
appearance of solar intranetwork (IN) magnetic elements. To attack such a
problem, we use the Narrow-band Filter Imager (NFI) magnetograms from the Solar
Optical Telescope (SOT) on board \emph{Hinode}; these data are from quiet and
an enhanced network areas. Cluster emergence of mixed polarities and IN
ephemeral regions (ERs) are the most conspicuous forms of bipolar flux
appearance within the network. Each of the clusters is characterized by a few
well-developed ERs that are partially or fully co-aligned in magnetic axis
orientation. On average, the sampled IN ERs have total maximum unsigned flux of
several 10^{17} Mx, separation of 3-4 arcsec, and a lifetime of 10-15 minutes.
The smallest IN ERs have a maximum unsigned flux of several 10^{16} Mx,
separations less than 1 arcsec, and lifetimes as short as 5 minutes. Most IN
ERs exhibit a rotation of their magnetic axis of more than 10 degrees during
flux emergence. Peculiar flux appearance, e.g., bipole shrinkage followed by
growth or the reverse, is not unusual. A few examples show repeated
shrinkage-growth or growth-shrinkage, like magnetic floats in the dynamic
photosphere. The observed bipolar behavior seems to carry rich information on
magneto-convection in the sub-photospheric layer.Comment: 26 pages, 14 figure
Topological String Amplitudes, Complete Intersection Calabi-Yau Spaces and Threshold Corrections
We present the most complete list of mirror pairs of Calabi-Yau complete
intersections in toric ambient varieties and develop the methods to solve the
topological string and to calculate higher genus amplitudes on these compact
Calabi-Yau spaces. These symplectic invariants are used to remove redundancies
in examples. The construction of the B-model propagators leads to compatibility
conditions, which constrain multi-parameter mirror maps. For K3 fibered
Calabi-Yau spaces without reducible fibers we find closed formulas for all
genus contributions in the fiber direction from the geometry of the fibration.
If the heterotic dual to this geometry is known, the higher genus invariants
can be identified with the degeneracies of BPS states contributing to
gravitational threshold corrections and all genus checks on string duality in
the perturbative regime are accomplished. We find, however, that the BPS
degeneracies do not uniquely fix the non-perturbative completion of the
heterotic string. For these geometries we can write the topological partition
function in terms of the Donaldson-Thomas invariants and we perform a
non-trivial check of S-duality in topological strings. We further investigate
transitions via collapsing D5 del Pezzo surfaces and the occurrence of free Z2
quotients that lead to a new class of heterotic duals.Comment: 117 pages, 1 Postscript figur
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