9,575 research outputs found
Dynamic response of phenolic resin and its carbon-nanotube composites to shock wave loading
We investigate with nonreactive molecular dynamics simulations the dynamic response of phenolic resin and its carbon-nanotube (CNT) composites to shock wave compression. For phenolic resin, our simulations yield shock states in agreement with experiments on similar polymers except the
“phase change” observed in experiments, indicating that such phase change is chemical in nature. The elastic–plastic transition is characterized by shear stress relaxation and atomic-level slip, and phenolic resin shows strong strain hardening. Shock loading of the CNT-resin composites is applied parallel or perpendicular to the CNT axis, and the composites demonstrate anisotropy in wave
propagation, yield and CNT deformation. The CNTs induce stress concentrations in the composites and may increase the yield strength. Our simulations suggest that the bulk shock response of the composites depends on the volume fraction, length ratio, impact cross-section, and geometry of the CNT components; the short CNTs in current simulations have insignificant effect on the bulk
response of resin polymer
The magnetic field effect on the transport and efficiency of group III tris(8-hydroxyquinoline) organic light emitting diodes
Copyright 2008 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Journal of Applied Physics 103, 103715 (2008) and may be found at
Phase retrieval by hyperplanes
We show that a scalable frame does phase retrieval if and only if the
hyperplanes of its orthogonal complements do phase retrieval. We then show this
result fails in general by giving an example of a frame for which
does phase retrieval but its induced hyperplanes fail phase retrieval.
Moreover, we show that such frames always exist in for any
dimension . We also give an example of a frame in which fails
phase retrieval but its perps do phase retrieval. We will also see that a
family of hyperplanes doing phase retrieval in must contain at
least hyperplanes. Finally, we provide an example of six hyperplanes in
which do phase retrieval
Detection of a fast, intense and unusual gamma ray transient
An unusual transient pulse of approximately 50 keV was detected by the gamma-ray burst sensor network using nine space probes and satellites. Its characteristics are unlike those of the known variety of gamma-ray bursts and therefore suggest that it was formed either by a completely different origin species or in a very different manner. It is identified with the LMC supernova remnant N49
Three precise gamma-ray burst source locations
The precise source regions of three moderately intense gamma ray bursts are derived. These events were observed with the first interplanetary burst sensor network. The optimum locations of the detectors, widely separated throughout the inner solar system, allowed for high accuracy, over-determined source fields of size 0.7 to 7.0 arc-min(2). All three locations are at fairly high galactic latitude in regions of low source confusion; none can be identified with a steady source object. Archived photographs were searched for optical transients that are able to be associated with these source fields; one such association was made
Affective symptoms and risk of progression to mild cognitive impairment or dementia in subjective cognitive decline: A systematic review and meta-analysis
Aims:
To systematically review the literature on outcomes for individuals with subjective cognitive decline (SCD) with concurrent affective symptoms. To conduct a meta-analysis to establish whether either higher depressive symptoms or higher levels of anxiety increased the risk of progression SCD to mild cognitive impairment (MCI) or dementia. /
Methods:
Five databases were searched from inception to February 2021 for longitudinal studies of older adults with SCD, reporting depressive and anxiety symptoms at baseline and risk of MCI or dementia at follow-up. Data were extracted and pooled using a random-effects meta-analysis. /
Results:
Twelve studies were identified. Pooled effect sizes indicated higher depressive symptoms did not increase risk of clinical progression to either MCI (RR = 0.98; 95% CI: 0.75 – 1.26) or dementia (RR = 0.69; 95% CI: 0.27 – 1.79). However, presence of anxiety or SCD-related worry did significantly increase risk of progression from subjective to objective cognitive impairment by 40% (RR = 1.40; 95% CI:1.20 – 1.63). /
Conclusions:
Affective symptoms in the form of anxiety, but not depressive symptoms, increase the risk of progression to objective cognitive impairment in individuals with SCD. Further research should focus on establishing whether psychological interventions aimed at reducing anxiety and worry also reduce the risk of clinical progression
Supersymmetry and Generic BSM Models in PYTHIA 8
We describe the implementation of supersymmetric models in PYTHIA 8,
including production and decay of superparticles and allowing for violation of
flavour, CP, and R-parity. We also present a framework for importing generic
new-physics matrix elements into PYTHIA 8, in a way suitable for use with
automated tools. We emphasize that this possibility should not be viewed as the
only way to implement new-physics models in PYTHIA 8, but merely as an
additional possibility on top of the already existing ones. Finally we address
parton showers in exotic colour topologies, in particular ones involving colour
epsilon tensors and colour sextets.Comment: 20 page
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