1,035 research outputs found
Phenomenological Model of Corrosion Process in Reinforced Concrete identified by AE
Corrosion of reinforcing steel is modelled phenomenologically as corrosion losses of three phases.   In order to identify the corrosion process in reinforced concrete based on the model, continuous AE monitoring in reinforced concrete specimens was conducted in an accelerated corrosion test and a cyclic wet and dry test.   It is demonstrated that two periods of high AE activities are observed.  The 1st AE activity corresponds to the onset of the corrosion in rebar of the 1st phase in the phenomenological model.  At the 2nd period of high activity AE events result from concrete cracking, corresponding to the 3rd phase in the model
Improved bounds on SUSY accompanied neutrinoless double beta decay
Neutrinoless double beta decay induced by light Majorana neutrino exchange
between two decaying nucleons with squark/slepton exchange inside one and W
exchange inside the other nucleon (so-called vector-scalar exchange) gives
stringent limits on R-parity violating interactions. We have extended previous
work by including the tensor contribution to the transition rate. We discuss
the improved limits on trilinear \Rp -MSSM couplings imposed by the current
experimental limit on the \znbb decay half-life of Ge.Comment: replaced by revised version to appear in Phys. Lett.
Non-collapsing renormalized QRPA with proton-neutron pairing for neutrinoless double beta decay
Using the renormalized quasiparticle random phase approximation (RQRPA), we
calculate the light neutrino mass mediated mode of neutrinoless double beta
decay of Ge76, Mo100, Te128 and Te130. Our results indicate that the simple
quasiboson approximation is not good enough to study the neutrinoless double
beta decay, because its solutions collapse for physical values of g_pp. We find
that extension of the Hilbert space and inclusion of the Pauli Principle in the
QRPA with proton-neutron pairing, allows us to extend our calculations beyond
the point of collapse, for physical values of the nuclear force strength. As a
consequence one might be able to extract more accurate values on the effective
neutrino mass by using the best available experimental limits on the half-life
of neutrinoless double beta decay.Comment: 15 pages, RevTex, 2 Postscript figures, to appear in Phys. Lett.
Conditions for detecting CP violation via neutrinoless double beta decay
Neutrinoless double beta decay data together with information on the absolute
neutrino masses obtained from the future KATRIN experiment and/or astrophysical
measurements give a chance to find CP violation in the lepton sector with
Majorana neutrinos. We derive and discuss necessary conditions which make
discovery of such CP violation possible for the future neutrino oscillation and
mass measurements data.Comment: 15 pages, 4 figures, RevTe
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Reduced Visual Cortex Gray Matter Volume and Thickness in Young Adults Who Witnessed Domestic Violence during Childhood
Exposure to interparental violence is associated with negative outcomes, such as depression, post-traumatic stress disorder and reduced cognitive abilities. However, little is known about the potential effects of witnessing domestic violence during childhood on gray matter volume (GMV) or cortical thickness. High-resolution 3.0 T volumetric scans (Siemens Trio Scanner) were obtained on 52 subjects (18–25 years) including 22 (6 males/16 females) with a history of visually witnessing episodes of domestic violence, and 30 (8 males/22 females) unexposed control subjects, with neither a current nor past DSM-IV Axis I or II disorder. Potential confounding effects of age, gender, level of parental verbal aggression, parental education, financial stress, full scale IQ, and total GMV, or average thickness were modeled using voxel based morphometry and FreeSurfer. Witnessing domestic violence subjects had a 6.1% GMV reduction in the right lingual gyrus (BA18) (P = 0.029, False Discovery Rate corrected peak level). Thickness in this region was also reduced, as was thickness in V2 bilaterally and left occipital pole. Theses regions were maximally sensitive to exposure to witnessing domestic violence between 11–13 years of age. Regional reductions in GMV and thickness were observed in both susceptible and resilient witnessing domestic violence subjects. Results in subjects witnessing domestic violence were similar to previously reported results in subjects with childhood sexual abuse, as the primary region affected was visual cortex. Brain regions that process and convey the adverse sensory input of the abuse may be specifically modified by this experience, particularly in subjects exposed to a single type of maltreatment. Exposure to multiple types of maltreatment is more commonly associated with morphological alterations in corticolimbic regions. These findings fit with preclinical studies showing that visual cortex is a highly plastic structure
Shell Model Study of the Double Beta Decays of Ge, Se and Xe
The lifetimes for the double beta decays of Ge, Se and
Xe are calculated using very large shell model spaces. The two neutrino
matrix elements obtained are in good agreement with the present experimental
data. For eV we predict the following upper bounds to the
half-lives for the neutrinoless mode: , and . These results are the first from a new generation of Shell
Model calculations reaching O(10) dimensions
Neutrino-less Double Electron Capture - a tool to research for Majorana neutrinos
The possibility to observe the neutrino-less double decay and thus
to prove the Majorana nature of neutrino as well as provide a sensitive measure
of its mass is a major challenge of to-day's neutrino physics. As an attractive
alternative we propose to study the inverse process, the radiative
neutrino-less double electron capture . The associated monoenergetic
photon provides a convenient experimental signature. Other advantages include
the favourable ratio of the to the competing capture
rates and, very importantly, the existence of coincidence trigger to suppress
the random background. These advantages partly offset the expected longer
lifetimes. Rates for the process are calculated. High Z atoms are
strongly favoured. A resonance enhancement of the capture rates is predicted at
energy release comparable to the atomic level difference. The resonance
conditions are likely to be met for decays to excited states in final nuclei.
Candidates for such studies are considered. The experimental feasibility is
estimated and found highly encouraging.Comment: New figure added, table updated, physical background discusse
A large Hilbert space QRPA and RQRPA calculation of neutrinoless double beta decay
A large Hilbert space is used for the calculation of the nuclear matrix
elements governing the light neutrino mass mediated mode of neutrinoless double
beta decay of Ge76, Mo100, Cd116, Te128 and Xe136 within the proton-neutron
quasiparticle random phase approximation (pn-QRPA) and the renormalized QRPA
with proton-neutron pairing (full-RQRPA) methods. We have found that the
nuclear matrix elements obtained with the standard pn-QRPA for several nuclear
transitions are extremely sensitive to the renormalization of the
particle-particle component of the residual interaction of the nuclear
hamiltonian. Therefore the standard pn-QRPA does not guarantee the necessary
accuracy to allow us to extract a reliable limit on the effective neutrino
mass. This behaviour, already known from the calculation of the two-neutrino
double beta decay matrix elements, manifests itself in the neutrinoless
double-beta decay but only if a large model space is used. The full-RQRPA,
which takes into account proton-neutron pairing and considers the Pauli
principle in an approximate way, offers a stable solution in the physically
acceptable region of the particle-particle strength. In this way more accurate
values on the effective neutrino mass have been deduced from the experimental
lower limits of the half-lifes of neutrinoless double beta decay.Comment: 19 pages, RevTex, 1 Postscript figur
Short-range correlations and neutrinoless double beta decay
In this work we report on the effects of short-range correlations upon the
matrix elements of neutrinoless double beta decay. We focus on the calculation
of the matrix elements of the neutrino-mass mode of neutrinoless double beta
decays of 48Ca and 76Ge. The nuclear-structure components of the calculation,
that is the participant nuclear wave functions, have been calculated in the
shell-model scheme for 48Ca and in the proton-neutron quasiparticle
random-phase approximation (pnQRPA) scheme for 76Ge. We compare the traditional
approach of using the Jastrow correlation function with the more complete
scheme of the unitary correlation operator method (UCOM). Our results indicate
that the Jastrow method vastly exaggerates the effects of short-range
correlations on the neutrinoless double beta decay nuclear matrix elements.Comment: 12 pages, 3 figures, to appear in Physics Letters B (2007
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