397 research outputs found
Numerical simulations of sunspots
The origin, structure and evolution of sunspots are investigated using a numerical model. The compressible MHD equations are solved with physical parameter values that approximate the top layer of the solar convection zone. A three dimensional (3D) numerical code is used to solve the set of equations in cylindrical geometry, with the numerical domain in the form of a wedge. The linear evolution of the 3D solution is studied by perturbing an axisymmetric solution in the azimuthal direction. Steady and oscillating linear modes are obtained
Converging and diverging convection around axisymmetric magnetic flux tubes
A numerical model of idealized sunspots and pores is presented, where axisymmetric cylindrical domains are used with aspect ratios (radius versus depth) up to 4. The model contains a compressible plasma with density and temperature gradients simulating the upper layer of the Sun's convection zone. Non-linear magnetohydrodynamic equations are solved numerically and time-dependent solutions are obtained where the magnetic field is pushed to the centre of the domain by convection cells. This central magnetic flux bundle is maintained by an inner convection cell, situated next to it and with a flow such that there is an inflow at the top of the numerical domain towards the flux bundle. For aspect ratio 4, a large inner cell persists in time, but for lower aspect ratios it becomes highly time dependent. For aspect ratios 2 and 3 this inner convection cell is smaller, tends to be situated towards the top of the domain next to the flux bundle, and appears and disappears with time. When it is gone, the neighbouring cell (with an opposite sense of rotation, i.e. outflow at the top) pulls the magnetic field away from the central axis. As this happens a new inner cell forms with an inflow which pushes the magnetic field towards the centre. This suggests that to maintain their form, both pores and sunspots need a neighbouring convection cell with inflow at the top towards the magnetic flux bundle. This convection cell does not have to be at the top of the convection zone and could be underneath the penumbral structure around sunspots. For an aspect ratio of 1, there is not enough space in the numerical domain for magnetic flux and convection to separate. In this case the solution oscillates between two steady states: two dominant convection cells threaded by magnetic field and one dominant cell that pushes magnetic flux towards the central axis
Pre-traumatic Factors of Career-Related PTSD: A Systematic Review of the Literature
This paper examined and synthesized the (limited) available literature on the pre-traumatic predictors of PTSD, specifically targeting populations in which traumatic events are experienced frequently because of the requirements of their positions, i.e., firefighters, police, and military personnel. A total of 21 articles were included in the final literature review and were used to assess the current available knowledge of the pre-traumatic traits of career-related PTSD, and address potential gaps in the literature. The culmination of this research was used to create specific risk profiles for each of the high risk careers included in this review, firefighters, police, and military personnel. The research presented here discovered very little literature surrounding these high risk populations. Future research focusing on longitudinal prospective studies should be conducted on high risk populations so that training could better equip officers, firefighters, and military personnel to deal with PTEs, thus lowering the overall development of PTSD
Heliophysics Event Knowledgebase for the Solar Dynamics Observatory and Beyond
The immense volume of data generated by the suite of instruments on SDO
requires new tools for efficient identifying and accessing data that is most
relevant to research investigations. We have developed the Heliophysics Events
Knowledgebase (HEK) to fill this need. The HEK system combines automated data
mining using feature-detection methods and high-performance visualization
systems for data markup. In addition, web services and clients are provided for
searching the resulting metadata, reviewing results, and efficiently accessing
the data. We review these components and present examples of their use with SDO
data.Comment: 17 pages, 4 figure
Estimating Electric Fields from Vector Magnetogram Sequences
Determining the electric field (E-field) distribution on the Sun's
photosphere is essential for quantitative studies of how energy flows from the
Sun's photosphere, through the corona, and into the heliosphere. This E-field
also provides valuable input for data-driven models of the solar atmosphere and
the Sun-Earth system. We show how Faraday's Law can be used with observed
vector magnetogram time series to estimate the photospheric E-field, an
ill-posed inversion problem. Our method uses a "poloidal-toroidal
decomposition" (PTD) of the time derivative of the vector magnetic field. The
PTD solutions are not unique; the gradient of a scalar potential can be added
to the PTD E-field without affecting consistency with Faraday's Law. We present
an iterative technique to determine a potential function consistent with ideal
MHD evolution; but this E-field is also not a unique solution to Faraday's Law.
Finally, we explore a variational approach that minimizes an energy functional
to determine a unique E-field, similar to Longcope's "Minimum Energy Fit". The
PTD technique, the iterative technique, and the variational technique are used
to estimate E-fields from a pair of synthetic vector magnetograms taken from an
MHD simulation; and these E-fields are compared with the simulation's known
electric fields. These three techniques are then applied to a pair of vector
magnetograms of solar active region NOAA AR8210, to demonstrate the methods
with real data.Comment: 41 pages, 10 figure
High Resolution Helioseismic Imaging of Subsurface Structures and Flows of A Solar Active Region Observed by Hinode
We analyze a solar active region observed by the Hinode CaII H line using the
time-distance helioseismology technique, and infer wave-speed perturbation
structures and flow fields beneath the active region with a high spatial
resolution. The general subsurface wave-speed structure is similar to the
previous results obtained from SOHO/MDI observations. The general subsurface
flow structure is also similar, and the downward flows beneath the sunspot and
the mass circulations around the sunspot are clearly resolved. Below the
sunspot, some organized divergent flow cells are observed, and these structures
may indicate the existence of mesoscale convective motions. Near the light
bridge inside the sunspot, hotter plasma is found beneath, and flows divergent
from this area are observed. The Hinode data also allow us to investigate
potential uncertainties caused by the use of phase-speed filter for short
travel distances. Comparing the measurements with and without the phase-speed
filtering, we find out that inside the sunspot, mean acoustic travel times are
in basic agreement, but the values are underestimated by a factor of 20-40%
inside the sunspot umbra for measurements with the filtering. The initial
acoustic tomography results from Hinode show a great potential of using
high-resolution observations for probing the internal structure and dynamics of
sunspots.Comment: accepted for publication in Ap
Enhanced Approaches for Identifying Amadori Products: Application to Peanut Allergens
The dry roasting of peanuts is suggested to influence allergic sensitization as a result of the formation of advanced glycation end products (AGEs) on peanut proteins. Identifying AGEs is technically challenging. The AGEs of a peanut allergen were probed with nano-scale liquid chromatography−electrospray ionization−mass spectrometry (nanoLC−ESI−MS) and tandem mass spectrometry (MS/MS) analyses. Amadori product ions matched to expected peptides and yielded fragments that included a loss of three waters and HCHO. As a result of the paucity of b and y ions in the MS/MS spectrum, standard search algorithms do not perform well. Reactions with isotopically labeled sugars confirmed that the peptides contained Amadori products. An algorithm was developed on the basis of information content (Shannon entropy) and the loss of water and HCHO. Results with test data show that the algorithm finds the correct spectra with high precision, reducing the time needed to manually inspect data. Computational and technical improvements allowed for better identification of the chemical differences between modified and unmodified proteins
Impact of the 13-valent pneumococcal conjugate vaccine (pcv13) on invasive pneumococcal disease and carriage in Alaska
AbstractBackgroundAlaska Native (AN) children have experienced high rates of invasive pneumococcal disease (IPD). In March 2010, PCV13 was introduced statewide in Alaska. We evaluated the impact of PCV13 on IPD in children and adults, 45 months after introduction.MethodsPneumococcal sterile site isolates, reported through state-wide surveillance, were serotyped using standard methods. We defined a pre-PCV13 time period 2005–2008 and post-PCV13 time period April 2010–December 2013; excluding Jan 2009–March 2010 because PCV13 was introduced pre-licensure in one high-risk region in 2009.ResultsAmong Alaska children <5 years, PCV13 serotypes comprised 65% of IPD in the pre-PCV13 period and 26% in the PCV13 period. Among all Alaska children <5 years, IPD rates decreased from 60.9 (pre) to 25.4 (post) per 100,000/year (P<0.001); PCV13 serotype IPD decreased from 37.7 to 6.4 (P<0.001). Among AN children <5 years, IPD rates decreased from 149.2 to 60.8 (P<0.001); PCV13 serotype IPD decreased from 87.0 to 17.4 (P<0.001); non-PCV13 serotype IPD did not change significantly. Among persons 5–17 and ≥45 years, the post-vaccine IPD rate was similar to the baseline period, but declined in persons 18–44 years (39%, P<0.001); this decline was similar in AN and non-AN persons (38%, P=0.016, 43%, P=0.014, respectively).ConclusionsForty-five months after PCV13 introduction, overall IPD and PCV13-serotype IPD rates had decreased 58% and 83%, respectively, in Alaska children <5 years of age when compared with 2005–2008. We observed evidence of indirect effect among adults with a 39% reduction in IPD among persons 18–44 years
GODAE systems in operation
During the last 15 years, operational oceanography systems have been
developed in several countries around the world. These developments have been
fostered primarily by the Global Ocean Data Assimilation Experiment (GODAE),
which coordinated these activities, encouraged partnerships, and facilitated
constructive competition. This multinational coordination has been very beneficial
for the development of operational oceanography. Today, several systems provide
routine, real-time ocean analysis, forecast, and reanalysis products. These systems
are based on (1) state-of-the-art Ocean General Circulation Model (OGCM)
configurations, either global or regional (basin-scale), with resolutions that range
from coarse to eddy-resolving, and (2) data assimilation techniques ranging from
analysis correction to advanced three- or four-dimensional variational schemes. These
systems assimilate altimeter sea level anomalies, sea surface temperature data, and
in situ profiles of temperature and salinity, including Argo data. Some systems have
implemented downscaling capacities, which consist of embedding higher-resolution
local systems in global and basin-scale models (through open boundary exchange of
data), especially in coastal regions, where small scale-phenomena are important, and
also increasing the spatial resolution for these regional/coastal systems to be able to
resolve smaller scales (so-called downscaling). Others have implemented coupling
with the atmosphere and/or sea ice. This paper provides a short review of these
operational GODAE systems.Published76-914.6. Oceanografia operativa per la valutazione dei rischi in aree marineN/A or not JCRope
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