1,412 research outputs found
Structure of the near-surface layers of the Sun: asphericity and time variation
We present results on the structure of the near-surface layers of the Sun
obtained by inverting frequencies of high-degree solar modes from "ring
diagrams". We have results for eight epochs between June 1996 and October 2003.
The frequencies for each epoch were obtained from ring diagrams constructed
from MDI Dopplergrams spanning complete Carrington rotations. We find that
there is a substantial latitudinal variation of both sound speed and the
adiabatic index Gamma_1 in the outer 2% of the Sun. We find that both the
sound-speed and Gamma_1 profiles change with changes in the level of solar
activity. In addition, we also study differences between the northern and
southern hemispheres of the Sun and find a small asymmetry that appears to
reflect the difference in magnetic activity between the two hemispheres.Comment: To appear in ApJ (January 2007
Novel Approaches of Chemoradiotherapy in Unresectable Stage IIIA and Stage IIIB Non-Small Cell Lung Cancer
After completing this course, the reader will be able to
Loss of Prestin Does Not Alter the Development of Auditory Cortical Dendritic Spines
Disturbance of sensory input during development can have disastrous effects on the development of sensory cortical areas. To examine how moderate perturbations of hearing can impact the development of primary auditory cortex, we examined markers of excitatory synapses in mice who lacked prestin, a protein responsible for somatic electromotility of cochlear outer hair cells. While auditory brain stem responses of these mice show an approximately 40 dB increase in threshold, we found that loss of prestin produced no changes in spine density or morphological characteristics on apical dendrites of cortical layer 5 pyramidal neurons. PSD-95 immunostaining also showed no changes in overall excitatory synapse density. Surprisingly, behavioral assessments of auditory function using the acoustic startle response showed only modest changes in prestin KO animals. These results suggest that moderate developmental hearing deficits produce minor changes in the excitatory connectivity of layer 5 neurons of primary auditory cortex and surprisingly mild auditory behavioral deficits in the startle response
Measuring Relations Between Concepts In Conceptual Spaces
The highly influential framework of conceptual spaces provides a geometric
way of representing knowledge. Instances are represented by points in a
high-dimensional space and concepts are represented by regions in this space.
Our recent mathematical formalization of this framework is capable of
representing correlations between different domains in a geometric way. In this
paper, we extend our formalization by providing quantitative mathematical
definitions for the notions of concept size, subsethood, implication,
similarity, and betweenness. This considerably increases the representational
power of our formalization by introducing measurable ways of describing
relations between concepts.Comment: Accepted at SGAI 2017 (http://www.bcs-sgai.org/ai2017/). The final
publication is available at Springer via
https://doi.org/10.1007/978-3-319-71078-5_7. arXiv admin note: substantial
text overlap with arXiv:1707.05165, arXiv:1706.0636
The Virtual Solar Observatory: What Are We Up To Now?
In the nearly ten years of a functional Virtual Solar Observatory (VSO), http://virtualsolar.org/ we have made it possible to query and access sixty-seven distinct solar data products and several event lists from nine spacecraft and fifteen observatories or observing networks. We have used existing VSO technology, and developed new software, for a distributed network of sites caching and serving SDO HMI and/ or AlA data. We have also developed an application programming interface (API) that has enabled VSO search and data access capabilities in IDL, Python, and Java. We also have quite a bit of work yet to do, including completion of the implementation of access to SDO EVE data, and access to some nineteen other data sets from space- and ground-based observatories. In addition, we have been developing a new graphic user interface that will enable the saving of user interface and search preferences. We solicit advice from the community input prioritizing our task list, and adding to i
Pruning Algorithms for Pretropisms of Newton Polytopes
Pretropisms are candidates for the leading exponents of Puiseux series that
represent solutions of polynomial systems. To find pretropisms, we propose an
exact gift wrapping algorithm to prune the tree of edges of a tuple of Newton
polytopes. We prefer exact arithmetic not only because of the exact input and
the degrees of the output, but because of the often unpredictable growth of the
coordinates in the face normals, even for polytopes in generic position. We
provide experimental results with our preliminary implementation in Sage that
compare favorably with the pruning method that relies only on cone
intersections.Comment: exact, gift wrapping, Newton polytope, pretropism, tree pruning,
accepted for presentation at Computer Algebra in Scientific Computing, CASC
201
A Multidisciplinary Childrens Airway Center: Impact on the Care of Patients With Tracheostomy
BACKGROUND: Children with complex airway problems see multiple specialists. To improve outcomes and coordinate care, we developed a multidisciplinary Children's Airway Center. For children with tracheostomies, aspects of care targeted for improvement included optimizing initial hospital discharge, promoting effective communication between providers and caregivers, and avoiding tracheostomy complications.
METHODS: The population includes children up to 21 years old with tracheostomies. The airway center team includes providers from pediatric pulmonology, pediatric otolaryngology/head and neck surgery, and pediatric gastroenterology. Improvement initiatives included enhanced educational strategies, weekly care conferences, institutional consensus guidelines and care plans, personalized clinic schedules, and standardized intervals between airway examinations. A patient database allowed for tracking outcomes over time.
RESULTS: We initially identified 173 airway center patients including 123 with tracheostomies. The median number of new patients evaluated by the center team each year was 172. Median hospitalization after tracheostomy decreased from 37 days to 26 days for new tracheostomy patients <1 year old discharged from the hospital. A median of 24 care plans was evaluated at weekly conferences. Consensus protocol adherence increased likelihood of successful decannulation from 68% to 86% of attempts. The median interval of 8 months between airway examinations aligned with published recommendations.
CONCLUSIONS: For children with tracheostomies, our Children's Airway Center met and sustained goals of optimizing hospitalization, promoting communication, and avoiding tracheostomy complications by initiating targeted improvements in a multidisciplinary team setting. A multidisciplinary approach to management of these patients can yield measurable improvements in important outcomes
Few smooth d-polytopes with n lattice points
We prove that, for fixed n there exist only finitely many embeddings of
Q-factorial toric varieties X into P^n that are induced by a complete linear
system. The proof is based on a combinatorial result that for fixed nonnegative
integers d and n, there are only finitely many smooth d-polytopes with n
lattice points. We also enumerate all smooth 3-polytopes with at most 12
lattice points. In fact, it is sufficient to bound the singularities and the
number of lattice points on edges to prove finiteness.Comment: 20+2 pages; major revision: new author, new structure, new result
Recommended from our members
Increasing the Availability and Consumption of Drinking Water in Middle Schools: A Pilot Study
Introduction: Although several studies suggest that drinking water may help prevent obesity, no US studies have examined the effect of school drinking water provision and promotion on student beverage intake. We assessed the acceptability, feasibility, and outcomes of a school-based intervention to improve drinking water consumption among adolescents. Methods: The 5-week program, conducted in a Los Angeles middle school in 2008, consisted of providing cold, filtered drinking water in cafeterias; distributing reusable water bottles to students and staff; conducting school promotional activities; and providing education. Self-reported consumption of water, nondiet soda, sports drinks, and 100% fruit juice was assessed by conducting surveys among students (n = 876), preintervention and at 1 week and 2 months postintervention, from the intervention school and the comparison school. Daily water (in gallons) distributed in the cafeteria during the intervention was recorded. Results: After adjusting for sociodemographic characteristics and baseline intake of water at school, the odds of drinking water at school were higher for students at the intervention school than students at the comparison school. Students from the intervention school had higher adjusted odds of drinking water from fountains and from reusable water bottles at school than students from the comparison school. Intervention effects for other beverages were not significant. Conclusion: Provision of filtered, chilled drinking water in school cafeterias coupled with promotion and education is associated with increased consumption of drinking water at school. A randomized controlled trial is necessary to assess the intervention's influence on students' consumption of water and sugar-sweetened beverages, as well as obesity-related outcomes
Local helioseismology of sunspot regions: comparison of ring-diagram and time-distance results
Local helioseismology provides unique information about the subsurface
structure and dynamics of sunspots and active regions. However, because of
complexity of sunspot regions local helioseismology diagnostics require careful
analysis of systematic uncertainties and physical interpretation of the
inversion results. We present new results of comparison of the ring-diagram
analysis and time-distance helioseismology for active region NOAA 9787, for
which a previous comparison showed significant differences in the subsurface
sound-speed structure, and discuss systematic uncertainties of the measurements
and inversions. Our results show that both the ring-diagram and time-distance
techniques give qualitatively similar results, revealing a characteristic
two-layer seismic sound-speed structure consistent with the results for other
active regions. However, a quantitative comparison of the inversion results is
not straightforward. It must take into account differences in the sensitivity,
spatial resolution and the averaging kernels. In particular, because of the
acoustic power suppression, the contribution of the sunspot seismic structure
to the ring-diagram signal can be substantially reduced. We show that taking
into account this effect reduces the difference in the depth of transition
between the negative and positive sound-speed variations inferred by these
methods. Further detailed analysis of the sensitivity, resolution and averaging
properties of the local helioseismology methods is necessary for consolidation
of the inversion results. It seems to be important that both methods indicate
that the seismic structure of sunspots is rather deep and extends to at least
20 Mm below the surface, putting constraints on theoretical models of sunspots.Comment: 10 pages, 10 figures, submitted to Journal of Physics: Conference
Series (JPCS) GONG 2010 - SoHO 24 "A new era of seismology of the Sun and
solar-like stars", June 27 - July 2, 2010 Aix-en-Provence, Franc
- …