349 research outputs found
Coronal Shock Waves, EUV waves, and Their Relation to CMEs. I. Reconciliation of "EIT waves", Type II Radio Bursts, and Leading Edges of CMEs
We show examples of excitation of coronal waves by flare-related abrupt
eruptions of magnetic rope structures. The waves presumably rapidly steepened
into shocks and freely propagated afterwards like decelerating blast waves that
showed up as Moreton waves and EUV waves. We propose a simple quantitative
description for such shock waves to reconcile their observed propagation with
drift rates of metric type II bursts and kinematics of leading edges of coronal
mass ejections (CMEs). Taking account of different plasma density falloffs for
propagation of a wave up and along the solar surface, we demonstrate a close
correspondence between drift rates of type II bursts and speeds of EUV waves,
Moreton waves, and CMEs observed in a few known events.Comment: 30 pages, 15 figures. Solar Physics, published online. The final
publication is available at http://www.springerlink.co
Search for the Proton Decay Mode proton to neutrino K+ in Soudan 2
We have searched for the proton decay mode proton to neutrino K+ using the
one-kiloton Soudan 2 high resolution calorimeter. Contained events obtained
from a 3.56 kiloton-year fiducial exposure through June 1997 are examined for
occurrence of a visible K+ track which decays at rest into mu+ nu or pi+ pi0.
We found one candidate event consistent with background, yielding a limit,
tau/B > 4.3 10^{31} years at 90% CL with no background subtraction.Comment: 13 pages, Latex, 3 tables and 3 figures, Accepted by Physics Letters
Predictors of care-giver stress in families of preschool-aged children with developmental disabilities
Background This study examined the predictors, mediators and moderators of parent stress in families of preschool-aged children with developmental disability. Method One hundred and five mothers of preschool-aged children with developmental disability completed assessment measures addressing the key variables. Results Analyses demonstrated that the difficulty parents experienced in completing specific caregiving tasks, behaviour problems during these caregiving tasks, and level of child disability, respectively, were significant predictors of level of parent stress. In addition, parents’ cognitive appraisal of care-giving responsibilities had a mediating effect on the relationship between the child’s level of disability and parent stress. Mothers’ level of social support had a moderating effect on the relationship between key independent variables and level of parent stress. Conclusions Difficulty of care-giving tasks, difficult child behaviour during care-giving tasks, and level of child disability are the primary factors which contribute to parent stress. Implications of these findings for future research and clinical practice are outlined
Detecting a stochastic gravitational wave background with the Laser Interferometer Space Antenna
The random superposition of many weak sources will produce a stochastic
background of gravitational waves that may dominate the response of the LISA
(Laser Interferometer Space Antenna) gravitational wave observatory. Unless
something can be done to distinguish between a stochastic background and
detector noise, the two will combine to form an effective noise floor for the
detector. Two methods have been proposed to solve this problem. The first is to
cross-correlate the output of two independent interferometers. The second is an
ingenious scheme for monitoring the instrument noise by operating LISA as a
Sagnac interferometer. Here we derive the optimal orbital alignment for
cross-correlating a pair of LISA detectors, and provide the first analytic
derivation of the Sagnac sensitivity curve.Comment: 9 pages, 11 figures. Significant changes to the noise estimate
Active Galactic Nuclei at the Crossroads of Astrophysics
Over the last five decades, AGN studies have produced a number of spectacular
examples of synergies and multifaceted approaches in astrophysics. The field of
AGN research now spans the entire spectral range and covers more than twelve
orders of magnitude in the spatial and temporal domains. The next generation of
astrophysical facilities will open up new possibilities for AGN studies,
especially in the areas of high-resolution and high-fidelity imaging and
spectroscopy of nuclear regions in the X-ray, optical, and radio bands. These
studies will address in detail a number of critical issues in AGN research such
as processes in the immediate vicinity of supermassive black holes, physical
conditions of broad-line and narrow-line regions, formation and evolution of
accretion disks and relativistic outflows, and the connection between nuclear
activity and galaxy evolution.Comment: 16 pages, 5 figures; review contribution; "Exploring the Cosmic
Frontier: Astrophysical Instruments for the 21st Century", ESO Astrophysical
Symposia Serie
Evolutionary Optimization of State Selective Field Ionization for Quantum Computing
State selective field ionization detection techniques in physics require a
specific progression through a complicated atomic state space to optimize state
selectivity and overall efficiency. For large principle quantum number n, the
theoretical models become computationally intractable and any results are often
rendered irrelevant by small deviations from ideal experimental conditions, for
example external electromagnetic fields. Several different proposals for
quantum information processing rely heavily upon the quality of these
detectors. In this paper, we show a proof of principle that it is possible to
optimize experimental field profiles in situ by running a genetic algorithm to
control aspects of the experiment itself. A simple experiment produced novel
results that are consistent with analyses of existing results.Comment: 9 pages, 5 figure
A study of the decay of 187W using a 2 m curved-crystal spectrometer
The gamma rays in the decay of 187W have been studied using the University of Michigan 2 m curved-crystal spectrometer and a lithium-drifted germanium diode spectrometer. One previously unreported transition has been observed and the energies of all observed transitions have been determined with the curved-crystal spectrometer. Upper limits have been determined for the intensities of possible unobserved gamma rays in the 160-1200 keV region. The relative merits and complementarity of the curved crystal spectrometer and the Ge(Li) spectrometer are discussed. In addition, data are presented concerning the reflectivity of the curved crystal using the germanium planes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33458/1/0000862.pd
Precision measurements of gamma-ray energies up to 2 MeV using a 2 m curved-crystal monochromator
Precision measurements of gamma-ray energies up to 2 MeV were performed using a 2m curved-crystal monochromator. Effective source activities of less than 40 mCur were used for the measurements of the transitions in the 2 MeV region. In the 150 keV region, effective source activities of less than 200 [mu]Cur may be used. Measurements have been performed on the transitions of energies less than 2150 keV which follow the decay of In116(54 min), Mn56 (2.6 h) and Sc46 (85 d). In addition, results are presented which indicate that the reflection coefficient is approximately linear with respect to wavelength for the second order reflection from the germanium (02) planes in the region of 6-90 mA (2000-135 keV).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31997/1/0000039.pd
Experimental investigation of rubidium atoms above the field-ionization limit using a time-resolved wave-packet approach
Safety assessment of essential medicines for elderly people: a bibliographic survey
Certain medicines are considered potentially inappropriate (PIM) for elderly people as they increase the risk of adverse drug events (ADE) and because safer alternative therapies are available on the market. In this context, in order to identify the instruments that assess the quality of medical prescriptions for elderly and to determine which drugs are considered PIM, a bibliographic survey was conducted in PUBMED, LILACS and PAHO databases, in February and March/2010. The search strategy included the use of health descriptors and a manual search in the references cited by selected papers. During the period of data collection, 15 instruments were identified. In 2012, with the publication of the update of Beers criteria, this instrument was included in the study. We identified 163 PIM of 25 therapeutic classes, of which 125 (76.7%) are marketed in Brazil. Of these, 31 (24.8%) are essential medicines (RENAME 2012), of which 13 have safer therapeutic equivalents and 19 (15.2%) are over-the-counter drugs. Data suggest the need for inclusion of safer alternatives for the elderly in the national list of essential medicines and the pharmaceutical care for early detection of ADE in this age group, in order to contribute to the safe use of medicines
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