12,166 research outputs found
A Common Origin for Ridge-and-Trough Terrain on Icy Satellites by Sluggish Lid Convection
Ridge-and-trough terrain is a common landform on outer Solar System icy
satellites. Examples include Ganymede's grooved terrain, Europa's gray bands,
Miranda's coronae, and several terrains on Enceladus. The conditions associated
with the formation of each of these terrains are similar: heat flows of order
tens to a hundred milliwatts per meter squared, and deformation rates of order
to s. Our prior work shows that the conditions
associated with the formation of these terrains on Ganymede and the south pole
of Enceladus are consistent with vigorous solid-state ice convection in a shell
with a weak surface. We show that sluggish lid convection, an intermediate
regime between the isoviscous and stagnant lid regimes, can create the heat
flow and deformation rates appropriate for ridge and trough formation on a
number of satellites, regardless of the ice shell thickness. For convection to
deform their surfaces, the ice shells must have yield stresses similar in
magnitude to the daily tidal stresses. Tidal and convective stresses deform the
surface, and the spatial pattern of tidal cracking controls the locations of
ridge-and-trough terrain.Comment: 45 pages, 7 figures; accepted for publication in Physics of the Earth
and Planetary Interior
Care of transgender patients by diagnostic radiographers: What can be learnt from the literature
Introduction: Transgender patients have described negative healthcare experiences, including discrimination and feeling unwelcome. Additionally, these patients are at risk of inadequate or unsafe care due to healthcare providers being unable to obtain and record transgender patients’ correct gender and assigned birth sex. This literature review aims to review radiology and radiographer articles published since 2018 about transgender healthcare issues and make recommendations that can be applied by diagnostic radiographers, their managers and diagnostic radiography programme providers.
Method: A literature search used multiple databases containing peer-reviewed articles. Boolean operators and key words were utilised. Identified articles were searched to identify any articles not found by searching the databases. Themes and sub-themes from each paper were identified and discussed.
Results: Three key themes were identified: education, systems and environment. Education sub-themes were knowledge and awareness. Systems sub-themes were recording gender correctly and discriminating/stigmatising policies. Environment sub-themes were transgender-friendly symbols and environmental dysphoria.
Conclusion: Transgender patients still face barriers to equitable care. Several recommendations were made based on the thematic discussion that could be applied by diagnostic radiographers, student radiographers, radiology managers, University training providers, and professional body organisations. Diagnostic radiography programmes should include training on both clinical topics and cultural competence. Radiology managers should display transgender-positive symbols in their departments and ensure their policies are non-discriminatory and non-stigmatising. Radiology hardware and software providers should provide the ability to record non-binary genders and birth-assigned sex.
Implications for Practice: Transgender patients have the right to receive equitable care from diagnostic radiographers during their imaging examination and radiology attendance, and that any risks relating to their transgender status should be correctly managed with appropriate sensitivity
Covariance analysis of the airborne laser ranging system
The requirements and limitations of employing an airborne laser ranging system for detecting crustal shifts of the Earth within centimeters over a region of approximately 200 by 400 km are presented. The system consists of an aircraft which flies over a grid of ground deployed retroreflectors, making six passes over the grid at two different altitudes. The retroreflector baseline errors are assumed to result from measurement noise, a priori errors on the aircraft and retroreflector positions, tropospheric refraction, and sensor biases
Experimental and numerical study of error fields in the CNT stellarator
Sources of error fields were indirectly inferred in a stellarator by
reconciling computed and numerical flux surfaces. Sources considered so far
include the displacements and tilts (but not the deformations, yet) of the four
circular coils featured in the simple CNT stellarator. The flux surfaces were
measured by means of an electron beam and phosphor rod, and were computed by
means of a Biot-Savart field-line tracing code. If the ideal coil locations and
orientations are used in the computation, agreement with measurements is poor.
Discrepancies are ascribed to errors in the positioning and orientation of the
in-vessel interlocked coils. To that end, an iterative numerical method was
developed. A Newton-Raphson algorithm searches for the coils' displacements and
tilts that minimize the discrepancy between the measured and computed flux
surfaces. This method was verified by misplacing and tilting the coils in a
numerical model of CNT, calculating the flux surfaces that they generated, and
testing the algorithm's ability to deduce the coils' displacements and tilts.
Subsequently, the numerical method was applied to the experimental data,
arriving at a set of coil displacements whose resulting field errors exhibited
significantly improved quantitative and qualitative agreement with experimental
results.Comment: Special Issue on the 20th International Stellarator-Heliotron
Worksho
Fermion Helicity Flip Induced by Torsion Field
We show that in theories of gravitation with torsion the helicity of fermion
particles is not conserved and we calculate the probability of spin flip, which
is related to the anti-symmetric part of affine connection. Some cosmological
consequences are discussed.Comment: 6 pages, to appear in Europhysics Letter
Spinless Matter in Transposed-Equi-Affine Theory of Gravity
We derive and discus the equations of motion for spinless matter:
relativistic spinless scalar fields, particles and fluids in the recently
proposed by A. Saa model of gravity with covariantly constant volume with
respect to the transposed connection in Einstein-Cartan spaces.
A new interpretation of this theory as a theory with variable Plank
"constant" is suggested.
We show that the consistency of the semiclassical limit of the wave equation
and classical motion dictates a new definite universal interaction of torsion
with massive fields.Comment: 29 pages, latex, no figures. New Section on semiclassical limit of
wave equation added; old references rearranged; new references, remarks,
comments, and acknowledgments added; typos correcte
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Evidence of neutral transcriptome evolution in plants
The transcriptome of an organism is its set of gene transcripts (mRNAs) at a defined spatial and temporal locus. Because gene expression is affected markedly by
environmental and developmental perturbations, it is widely assumed that transcriptome divergence among taxa represents adaptive phenotypic selection. This assumption has been challenged by neutral theories which propose that stochastic
processes drive transcriptome evolution. To test for evidence of neutral transcriptome evolution in plants, we quantified 18 494 gene transcripts in nonsenescent leaves of 14 taxa of Brassicaceae using robust cross-species transcriptomics which includes a two-step physical and in silicobased normalization procedure based on DNA similarity among taxa. Transcriptome divergence correlates positively with evolutionary distance between taxa and with variation in gene expression among samples. Results are similar for pseudogenes and chloroplast genes evolving at different rates. Remarkably, variation in transcript abundance among root-cell samples correlates positively with
transcriptome divergence among root tissues and among taxa.
Because neutral processes affect transcriptome evolution in plants, many differences in gene expression among or within taxa may be nonfunctional, reflecting ancestral
plasticity and founder effects. Appropriate null models are required when comparing transcriptomes in space and time
Morality, responsibility and risk: Gay men and proximity to HIV
No abstract available
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