667 research outputs found
Symmetries of pp-Waves with Distributional Profile
We generalize the classification of (non-vacuum) pp-waves \cite{JEK} based on
the Killing-algebra of the space-time by admitting distribution-valued profile
functions. Our approach is based on the analysis of the (infinite-dimensional)
group of ``normal-form-preserving'' diffeomorphisms.Comment: 10 pages, latex2e, no figures, statement about the combination of
symmetry classes of impulsive waves correcte
Glycerol confined in zeolitic imidazolate frameworks: The temperature-dependent cooperativity length scale of glassy freezing
In the present work, we employ broadband dielectric spectroscopy to study the
molecular dynamics of the prototypical glass former glycerol confined in two
microporous zeolitic imidazolate frameworks (ZIF-8 and ZIF-11) with
well-defined pore diameters of 1.16 and 1.46 nm, respectively. The spectra
reveal information on the modified alpha relaxation of the confined supercooled
liquid, whose temperature dependence exhibits clear deviations from the typical
super-Arrhenius temperature dependence of the bulk material, depending on
temperature and pore size. This allows assigning well-defined cooperativity
length scales of molecular motion to certain temperatures above the glass
transition. We relate these and previous results on glycerol confined in other
host systems to the temperature-dependent length scale deduced from nonlinear
dielectric measurements. The combined experimental data can be consistently
described by a critical divergence of this correlation length as expected
within theoretical approaches assuming that the glass transition is due to an
underlying phase transition.Comment: 14 pages, 5 figures + Supplemental Material (4 pages, 6 figures).
Final version as accepted for publicatio
Importance of reorientational dynamics for the charge transport in ionic liquids
Most ionic liquids contain at least one rather complex ion species exhibiting
a dipolar moment. In the present work, we provide a thorough evaluation of
broadband dielectric spectra of 12 ionic liquids taking into account the often
neglected reorientational dynamics of these ions. We confirm that this dynamics
leads to a clear relaxational signature in the spectra, a fact that so far only
was considered in few previous works. The obtained reorientational relaxation
times are well consistent with earlier inelastic light-scattering and
high-frequency dielectric investigations. Evaluating our dielectric spectra in
terms of reorientational motions reveals a close coupling of the ion-rotation
dynamics to the ionic charge transport in a broad temperature range from the
low-viscosity liquid above room temperature deep into the high-viscosity
supercooled state close to Tg. This coupling does not seem to be mediated by
the viscosity but probably is of more direct nature, pointing to a
revolving-door mechanism as also considered for plastic-crystalline ionic
conductors. Our results show that the reorientational motion of the dipolar
ions plays a significant and so far widely overlooked role for the ionic charge
transport in ionic liquids.Comment: 10 pages, 9 figures. Revised version according to suggestions of
referee
Dielectric study on mixtures of ionic liquids
Ionic liquids are promising candidates for electrolytes in energy-storage
systems. We demonstrate that mixing two ionic liquids allows to precisely tune
their physical properties, like the dc conductivity. Moreover, these mixtures
enable the gradual modification of the fragility parameter, which is believed
to be a measure of the complexity of the energy landscape in supercooled
liquids. The physical origin of this index is still under debate; therefore,
mixing ionic liquids can provide further insights. From the chemical point of
view, tuning ionic liquids via mixing is an easy and thus an economic way. For
this study, we performed detailed investigations by broadband dielectric
spectroscopy and differential scanning calorimetry on two mixing series of
ionic liquids. One series combines an imidazole based with a pyridine based
ionic liquid and the other two different anions in an imidazole based ionic
liquid. The analysis of the glass-transition temperatures and the thorough
evaluations of the measured dielectric permittivity and conductivity spectra
reveal that the dynamics in mixtures of ionic liquids are well defined by the
fractions of their parent compounds.Comment: 9 pages, 4 figure
People making deontological judgments in the Trapdoor dilemma are perceived to be more prosocial in economic games than they actually are
Why do people make deontological decisions, although they often lead to overall unfavorable outcomes? One account is receiving considerable attention: deontological judgments may signal commitment to prosociality and thus may increase people’s chances of being selected as social partners–which carries obvious long-term benefits. Here we test this framework by experimentally exploring whether people making deontological judgments are expected to be more prosocial than those making consequentialist judgments and whether they are actually so. In line with previous studies, we identified deontological choices using the Trapdoor dilemma. Using economic games, we take two measures of general prosociality towards strangers: trustworthiness and altruism. Our results procure converging evidence for a perception gap according to which Trapdoor-deontologists are believed to be more trustworthy and more altruistic towards strangers than Trapdoor-consequentialists, but actually they are not so. These results show that deontological judgments are not universal, reliable signals of prosociality
People making deontological judgments in the Trapdoor dilemma are perceived to be more prosocial in economic games than they actually are
Why do people make deontological decisions, although they often lead to overall unfavorable outcomes? One account is receiving considerable attention: deontological judgments may signal commitment to prosociality and thus may increase people’s chances of being selected as social partners–which carries obvious long-term benefits. Here we test this framework by experimentally exploring whether people making deontological judgments are expected to be more prosocial than those making consequentialist judgments and whether they are actually so. In line with previous studies, we identified deontological choices using the Trapdoor dilemma. Using economic games, we take two measures of general prosociality towards strangers: trustworthiness and altruism. Our results procure converging evidence for a perception gap according to which Trapdoor-deontologists are believed to be more trustworthy and more altruistic towards strangers than Trapdoor-consequentialists, but actually they are not so. These results show that deontological judgments are not universal, reliable signals of prosociality
People making deontological judgments in the Trapdoor dilemma are perceived to be more prosocial in economic games than they actually are
Characterization of Telehealth Use in Veterans with Spinal Cord Injuries and Disorders
BACKGROUND: Individuals with spinal cord injuries and disorders (SCI/D) require frequent interdisciplinary health care to address impairments in mobility, autonomic functions, and secondary complications. Telehealth has the capacity to substantially transform healthcare delivery and improve care by increasing access and communication. However, relatively little is known about telehealth use in this specific population. Here, we attempt to fill part of this gap.
OBJECTIVE: To investigate the frequency and characteristics associated with telehealth use in Veterans with SCI/D.
DESIGN: Cross-sectional, descriptive project
SETTING: Veterans Health Administration (VHA) facilities.
Participants: 15,028 Veterans living with SCI/D whom received services from the VHA SCI/D System of Care.
Intervention: Not applicable
Outcome Measures: Frequency and characteristics associated with VHA telehealth utilization.
Results: Of the 15,028 Veterans with SCI/D included in the evaluation, 17% used some form of telehealth in VHA Fiscal Year (FY)2017. Veterans over the age of 65 had lower odds (OR = 0.88, p \u3c 0.05, CI: 0.80-0.98) of using telehealth. Being Caucasian (OR = 1.29, p \u3c 0.01, CI: 1.09-1.52), living in rural areas (OR =1.16, p \u3c 0.01, CI: 1.05-1.28), living greater distances away from the VHA (p \u3c 0.01 for all distances), and being in priority group 8, meaning that Veterans have higher copayment requirements (OR=1.46, p \u3c 0.001, CI: 1.19-1.81), were all significantly associated with greater odds of telehealth use. The most frequent types of telehealth used were real-time clinical video and store-and-forward between a provider and patient within the same hub network.
Conclusion: There are opportunities to increase telehealth adoption in the SCI/D arena. The findings from this project highlight which Veterans are currently using telehealth services, as well as gaps regarding telehealth adoption in this population
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