97,780 research outputs found
Using the Coronal Evolution to Successfully Forward Model CMEs' In Situ Magnetic Profiles
Predicting the effects of a coronal mass ejection (CME) impact requires
knowing if impact will occur, which part of the CME impacts, and its magnetic
properties. We explore the relation between CME deflections and rotations,
which change the position and orientation of a CME, and the resulting magnetic
profiles at 1 AU. For 45 STEREO-era, Earth-impacting CMEs, we determine the
solar source of each CME, reconstruct its coronal position and orientation, and
perform a ForeCAT (Kay et al. 2015a) simulation of the coronal deflection and
rotation. From the reconstructed and modeled CME deflections and rotations we
determine the solar cycle variation and correlations with CME properties. We
assume no evolution between the outer corona and 1 AU and use the ForeCAT
results to drive the FIDO in situ magnetic field model (Kay et al. 2017a),
allowing for comparisons with ACE and Wind observations. We do not attempt to
reproduce the arrival time. On average FIDO reproduces the in situ magnetic
field for each vector component with an error equivalent to 35% of the average
total magnetic field strength when the total modeled magnetic field is scaled
to match the average observed value. Random walk best fits distinguish between
ForeCAT's ability to determine FIDO's input parameters and the limitations of
the simple flux rope model. These best fits reduce the average error to 30%.
The FIDO results are sensitive to changes of order a degree in the CME
latitude, longitude, and tilt, suggesting that accurate space weather
predictions require accurate measurements of a CME's position and orientation.Comment: accepted in JGR: Space Physic
Influence of Maternal Care on Behavioural Development of Domestic Dogs (Canis Familiaris) Living in a Home Environment
Maternal care has been shown to affect the development of the brain, behaviour, social skills and emotional systems of the young of many mammalian species including dogs. The aim of the present study was to determine the effects of maternal care on the behavioural responses of family dog puppies towards environmental and social stimuli. In order to do this, maternal care (licking puppy’s ano-genital area, licking the puppy, nursing and mother-puppy contact) during the first three weeks after birth was assessed in 12 litters of domestic dog puppies reared in home environments (total = 72 puppies). The behavioural responses of puppies were assessed in an arena and an isolation test, which were performed when the puppies were two-month old. Data were analysed using principal components analysis and projection to latent structures regression. A systematic relationship was found between maternal care and behaviour in both tests. In the arena test, maternal care was found to be positively associated with approach to the stranger, attention oriented to the stranger, time spent near the enclosure, yawning, whining and yelping (R2Y = 0.613, p = 8.2 × 10−9). Amount of maternal care was negatively associated with the number of squares crossed and the time spent individually playing with the rope. In the isolation test, the amount of maternal care was positively associated with standing posture, paw lifting, and howling, and it was negatively associated with yawning, lying down and nose licking (R2Y = 0.507, p = 0.000626). These results suggest that the amount of maternal care received during early life influences the pattern of behavioural responses and coping strategies of puppies at two-months of age. On the basis of these findings it could be speculated that early maternal care contributes to adaption to the environment in which family puppies are developing, with particular regard to social relationships with people
Predicting the magnetic vectors within coronal mass ejections arriving at Earth: 1. Initial Architecture
The process by which the Sun affects the terrestrial environment on short
timescales is predominately driven by the amount of magnetic reconnection
between the solar wind and Earth's magnetosphere. Reconnection occurs most
efficiently when the solar wind magnetic field has a southward component. The
most severe impacts are during the arrival of a coronal mass ejection (CME)
when the magnetosphere is both compressed and magnetically connected to the
heliospheric environment. Unfortunately, forecasting magnetic vectors within
coronal mass ejections remains elusive. Here we report how, by combining a
statistically robust helicity rule for a CME's solar origin with a simplified
flux rope topology the magnetic vectors within the Earth-directed segment of a
CME can be predicted. In order to test the validity of this proof-of-concept
architecture for estimating the magnetic vectors within CMEs, a total of eight
CME events (between 2010 and 2014) have been investigated. With a focus on the
large false alarm of January 2014, this work highlights the importance of
including the early evolutionary effects of a CME for forecasting purposes. The
angular rotation in the predicted magnetic field closely follows the broad
rotational structure seen within the in situ data. This time-varying field
estimate is implemented into a process to quantitatively predict a time-varying
Kp index that is described in detail in paper II. Future statistical work,
quantifying the uncertainties in this process, may improve the more heuristic
approach used by early forecasting systems.Comment: This paper has been published in Space Weather. Part two is currently
under revie
Healthy Schools Program Evaluation: Year 1 Update
Assesses the early impact of RWJF's program to provide technical assistance, resource brokering, and online tools to help schools promote physical activity and meet healthy foods and beverages standards. Examines improvement levels by school traits
Testing magnetofrictional extrapolation with the Titov-D\'emoulin model of solar active regions
We examine the nonlinear magnetofrictional extrapolation scheme using the
solar active region model by Titov and D\'emoulin as test field. This model
consists of an arched, line-tied current channel held in force-free equilibrium
by the potential field of a bipolar flux distribution in the bottom boundary. A
modified version, having a parabolic current density profile, is employed here.
We find that the equilibrium is reconstructed with very high accuracy in a
representative range of parameter space, using only the vector field in the
bottom boundary as input. Structural features formed in the interface between
the flux rope and the surrounding arcade-"hyperbolic flux tube" and "bald patch
separatrix surface"-are reliably reproduced, as are the flux rope twist and the
energy and helicity of the configuration. This demonstrates that force-free
fields containing these basic structural elements of solar active regions can
be obtained by extrapolation. The influence of the chosen initial condition on
the accuracy of reconstruction is also addressed, confirming that the initial
field that best matches the external potential field of the model quite
naturally leads to the best reconstruction. Extrapolating the magnetogram of a
Titov-D\'emoulin equilibrium in the unstable range of parameter space yields a
sequence of two opposing evolutionary phases which clearly indicate the
unstable nature of the configuration: a partial buildup of the flux rope with
rising free energy is followed by destruction of the rope, losing most of the
free energy.Comment: 14 pages, 10 figure
Comparison of individual and paired learning for the measurement of retention
Thesis (Ed.M.)--Boston UniversityThe purpose of this study was to measure and compare retention
between children working alone and with a partner using S.R.A.
(Scientific Research Associates) reading materials. The S.R.A.
laboratory is a series of graded reading experiences intended to be
used by individual children working alone and at their own rate of
speed. Its general purpose is to improve many reading skills but in
this study the retention factor will be the only concern
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