665 research outputs found
Adolescent Victims\u27 Experiences With Cyberbullying: A Grounded Theory Study
The purpose of this study was to construct a Grounded Theory that explains the processes involved in cyberbullying from the perspectives of those who have been victimized. A Constructivist Grounded Theory approach was used to explain the processes that occur as cyberbullying begins, unfolds, and ends, as well as to determine the methods that adolescent victims use to cope, and the context in which cyberbullying occurs.
Cyberbullying is a pervasive public health issue, affecting an estimated 10-30% of youth. Cyberbullying, though closely related to traditional physical bullying, has qualities that make it distinctive. Unlike traditional bullying, cyberbullying is relatively new in the literature and there are many elements of the phenomenon that we do not yet understand.
One-on-one, semi-structured interviews were conducted with 15 adolescent victims of cyberbullying. As a result of those interviews, a Grounded Theory titled Emerging from Cyberbullying was constructed and a theoretical model was developed. From these findings, we see that the victim moves through various stages during his/her experience. From Being Targeted, the victim becomes enveloped into a cyberbullying cycle that includes Being Cyberbullied, Losing Oneself, and Attempting to Cope. When the cyberbullying ceases, or the victim is no longer affected actively affected by it, he/she moves into a stage of Resolving and finally, Finding Oneself.
The findings from this study give hope that cyberbullying victims can arise from a cyberbullying experience feeling stronger and empowered to help others cope with cyberbullying victimization. Emerging from Cyberbullying gives us greater insight into the phenomenon of cyberbullying from the victims’ perspective and can be used to inform public health efforts aimed at preventing and intervening in cyberbullying behaviors
Relativistic calculations of the isotope shifts in highly charged Li-like ions
Relativistic calculations of the isotope shifts of energy levels in highly
charged Li-like ions are performed. The nuclear recoil (mass shift)
contributions are calculated by merging the perturbative and large-scale
configuration-interaction Dirac-Fock-Sturm (CI-DFS) methods. The nuclear size
(field shift) contributions are evaluated by the CI-DFS method including the
electron-correlation, Breit, and QED corrections. The nuclear deformation and
nuclear polarization corrections to the isotope shifts in Li-like neodymium,
thorium, and uranium are also considered. The results of the calculations are
compared with the theoretical values obtained with other methods.Comment: 28 page
Isotope shifts of the 2-2 transition in B-like ions
Isotope shifts of the 2-2 transition in B-like ions are
evaluated for a wide range of the nuclear charge number: Z=8-92. The
calculations of the relativistic nuclear recoil and nuclear size effects are
performed using a large scale configuration-interaction Dirac-Fock-Sturm
method. The corresponding QED corrections are also taken into account. The
results of the calculations are compared with the theoretical values obtained
with other methods. The accuracy of the isotope shifts of the
2-2 transition in B-like ions is significantly improved.Comment: arXiv admin note: text overlap with arXiv:1410.707
Dielectronic Recombination of Fe XV forming Fe XIV: Laboratory Measurements and Theoretical Calculations
We have measured resonance strengths and energies for dielectronic
recombination (DR) of Mg-like Fe XV forming Al-like Fe XIV via N=3 -> N' = 3
core excitations in the electron-ion collision energy range 0-45 eV. All
measurements were carried out using the heavy-ion Test Storage Ring at the Max
Planck Institute for Nuclear Physics in Heidelberg, Germany. We have also
carried out new multiconfiguration Breit-Pauli (MCBP) calculations using the
AUTOSTRUCTURE code. For electron-ion collision energies < 25 eV we find poor
agreement between our experimental and theoretical resonance energies and
strengths. From 25 to 42 eV we find good agreement between the two for
resonance energies. But in this energy range the theoretical resonance
strengths are ~ 31% larger than the experimental results. This is larger than
our estimated total experimental uncertainty in this energy range of +/- 26%
(at a 90% confidence level). Above 42 eV the difference in the shape between
the calculated and measured 3s3p(^1P_1)nl DR series limit we attribute partly
to the nl dependence of the detection probabilities of high Rydberg states in
the experiment. We have used our measurements, supplemented by our
AUTOSTRUCTURE calculations, to produce a Maxwellian-averaged 3 -> 3 DR rate
coefficient for Fe XV forming Fe XIV. The resulting rate coefficient is
estimated to be accurate to better than +/- 29% (at a 90% confidence level) for
k_BT_e > 1 eV. At temperatures of k_BT_e ~ 2.5-15 eV, where Fe XV is predicted
to form in photoionized plasmas, significant discrepancies are found between
our experimentally-derived rate coefficient and previously published
theoretical results. Our new MCBP plasma rate coefficient is 19-28% smaller
than our experimental results over this temperature range
Precision Spectroscopy at Heavy Ion Ring Accelerator SIS300
Unique spectroscopic possibilities open up if a laser beam interacts with
relativistic lithium-like ions stored in the heavy ion ring accelerator SIS300
at the future Facility for Antiproton and Ion Research FAIR in Darmstadt,
Germany. At a relativistic factor gamma = 36 the 2P 1/2 level can be excited
from the 2S 1/2 ground state for any element with frequency doubled dye-lasers
in collinear geometry. Precise transition energy measurements can be performed
if the fluorescence photons, boosted in forward direction into the X-ray
region, are energetically analyzed with a single crystal monochromator. The
hyperfine structure can be investigated at the 2P 1/2 - 2S 1/2 transition for
all elements and at the 2P 3/2 - 2S 1/2 transition for elements with Z < 50.
Isotope shifts and nuclear moments can be measured with unprecedented
precision, in principle even for only a few stored radioactive species with
known nuclear spin. A superior relative line width in the order of 5E-7 may be
feasible after laser cooling, and even polarized external beams may be prepared
by optical pumping
Absolute rate coefficients for photorecombination of berylliumlike and boronlike silicon ions
We report measured rate coefficients for electron-ion recombination for Si10+
forming Si9+ and for Si9+ forming Si8+, respectively. The measurements were
performed using the electron-ion merged-beams technique at a heavy-ion storage
ring. Electron-ion collision energies ranged from 0 to 50 eV for Si9+ and from
0 to 2000 eV for Si10+, thus, extending previous measurements for Si10+ [Orban
et al. 2010, Astrophys. J. 721, 1603] to much higher energies. Experimentally
derived rate coefficients for the recombination of Si9+ and Si10+ ions in a
plasma are presented along with simple parameterizations. These rate
coefficients are useful for the modeling of the charge balance of silicon in
photoionized plasmas (Si9+ and Si10+) and in collisionally ionized plasmas
(Si10+ only). In the corresponding temperature ranges, the experimentally
derived rate coefficients agree with the latest corresponding theoretical
results within the experimental uncertainties.Comment: 17 pages, 7 figures, 3 tables, 66 references, submitted to the J.
Phys. B special issue on atomic and molecular data for astrophysicist
High constitutive levels of heat-shock proteins in human-pathogenic parasites of the genus Leishmania
Commissioning of a continuous broadband data acquisition for Schottky signals in storage ring experiments at GSI and FAIR
Dielectronic Recombination in Photoionized Gas. II. Laboratory Measurements for Fe XVIII and Fe XIX
In photoionized gases with cosmic abundances, dielectronic recombination (DR)
proceeds primarily via nlj --> nl'j' core excitations (Dn=0 DR). We have
measured the resonance strengths and energies for Fe XVIII to Fe XVII and Fe
XIX to Fe XVIII Dn=0 DR. Using our measurements, we have calculated the Fe
XVIII and Fe XIX Dn=0 DR DR rate coefficients. Significant discrepancies exist
between our inferred rates and those of published calculations. These
calculations overestimate the DR rates by factors of ~2 or underestimate it by
factors of ~2 to orders of magnitude, but none are in good agreement with our
results. Almost all published DR rates for modeling cosmic plasmas are computed
using the same theoretical techniques as the above-mentioned calculations.
Hence, our measurements call into question all theoretical Dn=0 DR rates used
for ionization balance calculations of cosmic plasmas. At temperatures where
the Fe XVIII and Fe XIX fractional abundances are predicted to peak in
photoionized gases of cosmic abundances, the theoretical rates underestimate
the Fe XVIII DR rate by a factor of ~2 and overestimate the Fe XIX DR rate by a
factor of ~1.6. We have carried out new multiconfiguration Dirac-Fock and
multiconfiguration Breit-Pauli calculations which agree with our measured
resonance strengths and rate coefficients to within typically better than
<~30%. We provide a fit to our inferred rate coefficients for use in plasma
modeling. Using our DR measurements, we infer a factor of ~2 error in the Fe XX
through Fe XXIV Dn=0 DR rates. We investigate the effects of this estimated
error for the well-known thermal instability of photoionized gas. We find that
errors in these rates cannot remove the instability, but they do dramatically
affect the range in parameter space over which it forms.Comment: To appear in ApJS, 44 pages with 13 figures, AASTeX with postsript
figure
Nuclear deformation effect on the binding energies in heavy ions
Nuclear deformation effects on the binding energies in heavy ions are
investigated. Approximate formulas for the nuclear-size correction and the
isotope shift for deformed nuclei are derived. Combined with direct numerical
evaluations, these formulas are employed to reanalyse experimental data on the
nuclear-charge-distribution parameters in and to revise the
nuclear-size corrections to the binding energies in H- and Li-like
. As a result, the theoretical uncertainties for the
ground-state Lamb shift in and for the
transition energy in are significantly reduced. The
isotope shift of the transition energies for
and is also evaluated
including nuclear size and nuclear recoil effects within a full QED treatment.Comment: 19 pages, 5 table
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