50 research outputs found
Analysing the elasticity difference tensor of general relativity
The elasticity difference tensor, used in [1] to describe elasticity
properties of a continuous medium filling a space-time, is here analysed from
the point of view of the space-time connection. Principal directions associated
with this tensor are compared with eigendirections of the material metric.
Examples concerning spherically symmetric and axially symmetric space-times are
then presented.Comment: 17 page
Near-Infrared Spectral Monitoring of Triton with IRTF/SpeX II: Spatial Distribution and Evolution of Ices
This report arises from an ongoing program to monitor Neptune's largest moon
Triton spectroscopically in the 0.8 to 2.4 micron range using IRTF/SpeX. Our
objective is to search for changes on Triton's surface as witnessed by changes
in the infrared absorption bands of its surface ices N2, CH4, H2O, CO, and CO2.
We have recorded infrared spectra of Triton on 53 nights over the ten
apparitions from 2000 through 2009. The data generally confirm our previously
reported diurnal spectral variations of the ice absorption bands (Grundy &
Young 2004). Nitrogen ice shows a large amplitude variation, with much stronger
absorption on Triton's Neptune-facing hemisphere. We present evidence for
seasonal evolution of Triton's N2 ice: the 2.15 micron absorption band appears
to be diminishing, especially on the Neptune-facing hemisphere. Although it is
mostly dissolved in N2 ice, Triton's CH4 ice shows a very different
longitudinal variation from the N2 ice, challenging assumptions of how the two
ices behave. Unlike Triton's CH4 ice, the CO ice does exhibit longitudinal
variation very similar to the N2 ice, implying that CO and N2 condense and
sublimate together, maintaining a consistent mixing ratio. Absorptions by H2O
and CO2 ices show negligible variation as Triton rotates, implying very uniform
and/or high latitude spatial distributions for those two non-volatile ices.Comment: 22 pages, 13 figures, 5 tables, to appear in Icaru
Comparison of depression and anxiety symptom networks in reporters and non-reporters of lifetime trauma in two samples of differing severity
Background: Reported trauma is associated with differences in the course and outcomes of depression and anxiety. However, no research has explored the association between reported trauma and patterns of clinically relevant symptoms of both depression and anxiety. Methods: We used network analysis to investigate associations between reported trauma and depression and anxiety symptom interactions in affected individuals from the Genetic Links to Anxiety and Depression (GLAD) Study (n = 17720), and population volunteers from the UK Biobank (n = 11120). Participants with current moderate symptoms of depression or anxiety were grouped into reporters and non-reporters of lifetime trauma. Networks of 16 depression and anxiety symptoms in the two groups were compared using the network comparison test. Results: In the GLAD Study, networks of reporters and non-reporters of lifetime trauma did not differ on any metric. In the UK Biobank, the symptom network of reporters had significantly greater density (7.80) than the network of non-reporters (7.05). Limitations: The data collected in the GLAD Study and the UK Biobank are self-reported with validated or semi-validated questionnaires. Conclusions: Reported lifetime trauma was associated with stronger interactions between symptoms of depression and anxiety in population volunteers. Differences between reporters and non-reporters may not be observed in individuals with severe depression and/or anxiety due to limited variance in the presentation of disorder