678 research outputs found
Pediatric Terrorism Preparedness National Guidelines and Recommendations: Findings of an Evidenced-based Consensus Process
A cadre of experts and stakeholders from government agencies, professional organizations, emergency medicine and response, pediatrics, mental health, and disaster preparedness were gathered to review and summarize the existing data on the needs of children in the planning, preparation, and response to disasters or terrorism. This review was followed by development of evidence-based consensus guidelines and recommendations on the needs of children in disasters, including chemical, biological, and radiological terrorism. An evidence-based consensus process was used in conjunction with a modified Delphi approach for selection of topic areas and discussion points. These recommendations and guidelines represent the first national evidence-based standards for pediatric disaster and terrorism preparedness
Non-equilibrium raft-like membrane domains under continuous recycling
We present a model for the kinetics of spontaneous membrane domain (raft)
assembly that includes the effect of membrane recycling ubiquitous in living
cells. We show that the domains have a broad power-law distribution with an
average radius that scales with the 1/4 power of the domain lifetime when the
line tension at the domain edges is large. For biologically reasonable
recycling and diffusion rates the average domain radius is in the tens of nm
range, consistent with observations. This represents one possible link between
signaling (involving rafts) and traffic (recycling) in cells. Finally, we
present evidence that suggests that the average raft size may be the same for
all scale-free recycling schemes.Comment: 8 pages, 5 figure
Relativistic recoil, electron-correlation, and QED effects on the 2p_j-2s transition energies in Li-like ions
The relativistic nuclear recoil, higher-order interelectronic-interaction,
and screened QED corrections to the transition energies in Li-like ions are
evaluated. The calculation of the relativistic recoil effect is performed to
all orders in 1/Z. The interelectronic-interaction correction to the transition
energies beyond the two-photon exchange level is evaluated to all orders in 1/Z
within the Breit approximation. The evaluation is carried out employing the
large-scale configuration-interaction Dirac-Fock-Sturm method. The rigorous
calculation of the complete gauge invariant sets of the screened self-energy
and vacuum-polarization diagrams is performed utilizing a local screening
potential as the zeroth-order approximation. The theoretical predictions for
the 2p_j-2s transition energies are compiled and compared with available
experimental data in the range of the nuclear charge number Z=10-60.Comment: 39 pages, 3 figures, 11 table
Energy levels and lifetimes of Gd IV and enhancement of the electron dipole moment
We have calculated energy levels and lifetimes of 4f7 and 4f6 5d
configurations of Gd IV using Hartree-Fock and configuration interaction
methods. This allows us to reduce significantly the uncertainty of the
theoretical determination of the electron electric dipole moment (EDM)
enhancement factor in this ion and, correspondingly, in gadolinium-containing
garnets for which such measurements were recently proposed. Our new value for
the EDM enhancement factor of Gd+3 is -2.2 +- 0.5. Calculations of energy
levels and lifetimes for Eu~III are used to control the accuracy.Comment: Submitted to Phys. Rev. A 6 pages, 0 figures, 3 table
Soft X-ray emission lines of Fe XV in solar flare observations and the Chandra spectrum of Capella
Recent calculations of atomic data for Fe XV have been used to generate
theoretical line ratios involving n = 3-4 transitions in the soft X-ray
spectral region (52-83 A), for a wide range of electron temperatures and
densities applicable to solar and stellar coronal plasmas. A comparison of
these with solar flare observations from a rocket-borne spectrograph (XSST)
reveals generally good agreement between theory and experiment. In particular,
the 82.76 A emission line in the XSST spectrum is identified, for the first
time to our knowledge in an astrophysical source. Most of the Fe XV transitions
which are blended have had the species responsible clearly identified, although
there remain a few instances where this has not been possible. The line ratio
calculations are also compared with a co-added spectrum of Capella obtained
with the Chandra satellite, which is probably the highest signal-to-noise
observation achieved for a stellar source in the 25-175 A soft X-ray region.
Good agreement is found between theory and experiment, indicating that the Fe
XV lines are reliably detected in Chandra spectra, and hence may be employed as
diagnostics to determine the temperature and/or density of the emitting plasma.
However the line blending in the Chandra data is such that individual emission
lines are difficult to measure accurately, and fluxes may only be reliably
determined via detailed profile fitting of the observations. The co-added
Capella spectrum is made available to hopefully encourage further exploration
of the soft X-ray region in astronomical sources.Comment: 27 pages, 10 figures, Astrophysical Journal, in pres
Third-order relativistic many-body calculations of energies and lifetimes of levels along the silver isoelectronic sequence
Energies of 5l_j (l= s, p, d, f, g) and 4f_j states in neutral Ag and Ag-like
ions with nuclear charges Z = 48 - 100 are calculated using relativistic
many-body perturbation theory. Reduced matrix elements, oscillator strengths,
transition rates and lifetimes are calculated for the 17 possible 5l_j-5l'_{j'}
and 4f_j-5l_{j'} electric-dipole transitions. Third-order corrections to
energies and dipole matrix elements are included for neutral Ag and for ions
with Z60. Comparisons are made
with available experimental data for transition energies and lifetimes.
Correlation energies and transition rates are shown graphically as functions of
nuclear charge Z for selected cases. These calculations provide a theoretical
benchmark for comparison with experiment and theory.Comment: 8 page
Ten Simple Rules for Getting Help from Online Scientific Communities
The increasing complexity of research requires scientists to work at the intersection of multiple fields and to face problems for which their formal education has not prepared them. For example, biologists with no or little background in programming are now often using complex scripts to handle the results from their experiments; vice versa, programmers wishing to enter the world of bioinformatics must know about biochemistry, genetics, and other fields.
In this context, communication tools such as mailing lists, web forums, and online communities acquire increasing importance. These tools permit scientists to quickly contact people skilled in a specialized field. A question posed properly to the right online scientific community can help in solving difficult problems, often faster than screening literature or writing to publication authors. The growth of active online scientific communities, such as those listed in Table S1, demonstrates how these tools are becoming an important source of support for an increasing number of researchers.
Nevertheless, making proper use of these resources is not easy. Adhering to the social norms of World Wide Web communicationâloosely termed ânetiquetteââis both important and non-trivial.
In this article, we take inspiration from our experience on Internet-shared scientific knowledge, and from similar documents such as âAsking the Questions the Smart Wayâ and âGetting Answersâ, to provide guidelines and suggestions on how to use online communities to solve scientific problems
Space-Time Variation of Physical Constants and Relativistic Corrections in Atoms
Detection of high-redshift absorption in the optical spectra of quasars have
provided a powerful tool to measure spatial and temporal variations of physical
``constants'' in the Universe. It is demonstrated that high sensitivity to the
variation of the fine structure constant alpha can be obtained from a
comparison of the spectra of heavy and light atoms (or molecules). We have
performed calculations for the pair FeII and MgII for which accurate quasar and
laboratory spectra are available. A possibility of times enhanced
effects of the fundamental constants variation suitable for laboratory
measurements is also discussed.Comment: 8 pages; LaTeX; Submitted to Phys. Rev. Let
EVOLUTION OF MILK CATALASE ACTIVITY IN PRESENCE OF INHIBITOR AND ACTIVATOR SUBSTANCES
Milk catalase activity were carried out to determine the effect of different activators and inhibitors on enzyme activity. The experiments where conducted to estimate the catalase activity from fresh milk, fresh milk in addition with trichloroacetic acid, fresh milk in addition with tannin, fresh milk during the pasteurization process, fresh milk in addition with iron, fresh milk in addition with vitamins. Iron, vitamins, high temperature influence positive milk catalase activity; tannin, trichloroacetic acid and pasteurization temperature influence negative milk catalase activit
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