1,818 research outputs found
Assessing the relationship between spectral solar irradiance and stratospheric ozone using Bayesian inference
We investigate the relationship between spectral solar irradiance (SSI) and
ozone in the tropical upper stratosphere. We find that solar cycle (SC) changes
in ozone can be well approximated by considering the ozone response to SSI
changes in a small number individual wavelength bands between 176 and 310 nm,
operating independently of each other. Additionally, we find that the ozone
varies approximately linearly with changes in the SSI. Using these facts, we
present a Bayesian formalism for inferring SC SSI changes and uncertainties
from measured SC ozone profiles. Bayesian inference is a powerful,
mathematically self-consistent method of considering both the uncertainties of
the data and additional external information to provide the best estimate of
parameters being estimated. Using this method, we show that, given measurement
uncertainties in both ozone and SSI datasets, it is not currently possible to
distinguish between observed or modelled SSI datasets using available estimates
of ozone change profiles, although this might be possible by the inclusion of
other external constraints. Our methodology has the potential, using wider
datasets, to provide better understanding of both variations in SSI and the
atmospheric response.Comment: 21 pages, 4 figures, Journal of Space Weather and Space Climate
(accepted), pdf version is in draft mode of Space Weather and Space Climat
Relaxation energies and excited state structures of poly(para-phenylene)
We investigate the relaxation energies and excited state geometries of the
light emitting polymer, poly(para-phenylene). We solve the
Pariser-Parr-Pople-Peierls model using the density matrix renormalization group
method. We find that the lattice relaxation of the dipole-active
state is quite different from that of the state and the
dipole-inactive state. In particular, the state is
rather weakly coupled to the lattice and has a rather small relaxation energy
ca. 0.1 eV. In contrast, the and states are strongly
coupled with relaxation energies of ca. 0.5 and ca. 1.0 eV, respectively. By
analogy to linear polyenes, we argue that this difference can be understood by
the different kind of solitons present in the , and
states. The difference in relaxation energies of the
and states accounts for approximately one-third of the exchange
gap in light-emitting polymers.Comment: Submitted to Physical Review
BEMAS: A Belief Maintenance System Prototype User\u27s Manual
This paper is a user\u27s manual for BEMAS, a Belief Maintenance System. BEMAS is a menu driven system which provides an easy to use interface between a user and a knowledge base. Given a set of data, and a set of rules, BEMAS will help the user to identify an object by analyzing the properties of that object. Data can be added and deleted at any time, either directly or by deleting beliefs on which the data is dependent. BEMAS maintains the relations and dependencies between data using a dynamic dependency net. BEMAS also has the capability to make inferences using incomplete information while still maintaining knowledge base integrity
Functional Magnetic Resonance Imaging in Pediatrics
Functional magnetic resonance imaging (fMRI) allows non-invasive assessment of human brain function in vivo by detecting blood flow differences. In this review, we want to illustrate the background and different aspects of performing functional magnetic resonance imaging (fMRI) in the pediatric age group. An overview over current and future applications of fMRI will be given, and typical problems, pitfalls, and benefits of doing fMRI in the pediatric age group are discussed. We conclude that fMRI can successfully be applied in children and holds great promise for both research and clinical purposes
Lithospheric shear velocity structure of South Island, New Zealand, from amphibious Rayleigh wave tomography
Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 121 (2016): 3686–3702, doi:10.1002/2015JB012726.We present a crust and mantle 3-D shear velocity model extending well offshore of New Zealand's South Island, imaging the lithosphere beneath the South Island as well as the Campbell and Challenger Plateaus. Our model is constructed via linearized inversion of both teleseismic (18–70 s period) and ambient noise-based (8–25 s period) Rayleigh wave dispersion measurements. We augment an array of 4 land-based and 29 ocean bottom instruments deployed off the South Island's east and west coasts in 2009–2010 by the Marine Observations of Anisotropy Near Aotearoa experiment with 28 land-based seismometers from New Zealand's permanent GeoNet array. Major features of our shear wave velocity (Vs) model include a low-velocity (Vs 50 km) beneath the central South Island exhibits strong spatial correlation with upper mantle earthquake hypocenters beneath the Alpine Fault. The ~400 km long low-velocity zone we image beneath eastern South Island and the inner Bounty Trough underlies Cenozoic volcanics and the locations of mantle-derived helium measurements, consistent with asthenospheric upwelling in the region.National Science Foundation Grant Number: EAR-0409564, EAR-0409609, and EAR-04098352016-11-2
Effects of a College-Mentored Physical Activity Program for Elementary Students
Health risks of a sedentary lifestyle for children, defined as being less than 5,000 steps per day, include unfavorable indicators of body composition and cardio-metabolic risk. Results of school-based physical activity interventions to increase physical activity levels have been mixed. However, mentorship programs have shown promise. Previous mentorship programs have relied on peer-to-peer mentorships, with participants being of a similar age group. College mentors present an alternative and low-cost resource that may also provide positive results, yet have been largely ignored in research studies to date. PURPOSE: The purpose of this study was to investigate the impact of a novel, individualized college-mentored physical activity program on physical activity levels among older elementary school students. METHODS: Fifth grade students (n = 12) were paired one-to-one with local college mentors for 30 minute bi-weekly running sessions on the elementary school campus for six weeks. Multiple assessments from activity trackers were compared on intervention versus non-intervention days using paired-samples t-tests. RESULTS: Significant increases in steps (t(11) = 8.056; p ≤ .001) and moderate-to-vigorous activity (t(11) = 5.202; p ≤ .001) were seen on intervention days, as compared to non-intervention days. The average increase in step count on intervention days (6,381) versus non-intervention days (3,158) also resulted in students being elevated out of a sedentary classification. CONCLUSION: Individualized mentoring from college students significantly increased multiple assessments of physical activity, including minutes of moderate-to-vigorous activity and number of steps taken. Perhaps most notably, the mentored physical activity program promoted students from a sedentary to active lifestyle on intervention days as determined by step count. This novel high-impact and low-cost approach should be further developed for future school-based physical activity programs and research
Entanglement can increase asymptotic rates of zero-error classical communication over classical channels
It is known that the number of different classical messages which can be
communicated with a single use of a classical channel with zero probability of
decoding error can sometimes be increased by using entanglement shared between
sender and receiver. It has been an open question to determine whether
entanglement can ever increase the zero-error communication rates achievable in
the limit of many channel uses. In this paper we show, by explicit examples,
that entanglement can indeed increase asymptotic zero-error capacity, even to
the extent that it is equal to the normal capacity of the channel.
Interestingly, our examples are based on the exceptional simple root systems E7
and E8.Comment: 14 pages, 2 figur
Validity of an ultra-wideband local positioning system to measure locomotion in indoor sports
The validity of an Ultra-wideband (UWB) positioning system was investigated during linear and change-of-direction (COD) running drills. Six recreationally-active men performed ten repetitions of four activities (walking, jogging, maximal acceleration, and 45º COD) on an indoor court. Activities were repeated twice, in the centre of the court and on the side. Participants wore a receiver tag (Clearsky T6, Catapult Sports) and two reflective markers placed on the tag to allow for comparisons with the criterion system (Vicon). Distance, mean and peak velocity, acceleration, and deceleration were assessed. Validity was assessed via percentage least-square means difference (Clearsky-Vicon) with 90% confidence interval and magnitude-based inference; typical error was expressed as within-subject standard deviation. The mean differences for distance, mean/peak speed, and mean/peak accelerations in the linear drills were in the range of 0.2–12%, with typical errors between 1.2 and 9.3%. Mean and peak deceleration had larger differences and errors between systems. In the COD drill, moderate-to-large differences were detected for the activity performed in the centre of the court, increasing to large/very large on the side. When filtered and smoothed following a similar process, the UWB-based positioning system had acceptable validity, compared to Vicon, to assess movements representative of indoor sports
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