79,587 research outputs found
Open subgroups of the automorphism group of a right-angled building
We study the group of type-preserving automorphisms of a right-angled
building, in particular when the building is locally finite. Our aim is to
characterize the proper open subgroups as the finite index closed subgroups of
the stabilizers of proper residues.
One of the main tools is the new notion of firm elements in a right-angled
Coxeter group, which are those elements for which the final letter in each
reduced representation is the same. We also introduce the related notions of
firmness for arbitrary elements of such a Coxeter group and -flexibility of
chambers in a right-angled building. These notions and their properties are
used to determine the set of chambers fixed by the fixator of a ball. Our main
result is obtained by combining these facts with ideas by Pierre-Emmanuel
Caprace and Timoth\'ee Marquis in the context of Kac-Moody groups over finite
fields, where we had to replace the notion of root groups by a new notion of
root wing groups.Comment: 29 page
On a nonlinear theory of elastic shells
Nonlinear theory of elastic shells with deformation gradient
Vortex configurations and metastability in mesoscopic superconductors
The vortex dynamics in mesoscopic superconducting cylinders with rectangular
cross section under an axially applied magnetic field is investigated in the
multivortex London regime. The rectangles considered range from a square up to
an infinite slab. The flux distribution and total flux carried by a vortex
placed in an arbitrary position of the sample is calculated analytically by
assuming Clem's solution for the vortex core. The Bean-Livingston energy
barrier is also analytically calculated in this framework. A Langevin algorithm
simulates the flux penetration and dynamical evolution of the vortices as the
external field is slowly cycled. The simulated magnetization process is
governed by metastable states. The magnetization curves are hysteretic, with
paramagnetic response in part of the downward branch, and present a series of
peaks corresponding to the entry or expulsion of a single vortex. For elongated
rectangles, the vortices arrange themselves into parallel vortex chains and an
additional modulation of the magnetization, corresponding to creation or
destruction of a vortex chain, comes out.Comment: 7 pages, 4 figures. Presented on the III European Conference on
Vortex Matter in Superconductors, Crete, 2003. To appear in Physica
Dual consent? Donors' and recipients' views about involvement in decision-making on the use of embryos created by gamete donation in research
Background Reasonable disagreement about the role awarded to gamete donors in decision-making on the use of embryos created by gamete donation (EGDs) for research purposes emphasises the importance of considering the implementation of participatory, adaptive, and trustworthy policies and guidelines for consent procedures. However, the perspectives of gamete donors and recipients about decision-making regarding research with EGDs are still under-researched, which precludes the development of policies and guidelines informed by evidence. This study seeks to explore the views of donors and recipients about who should take part in consent processes for the use of EGDs in research. Methods From July 2017 to June 2018, 72 gamete donors and 175 recipients completed a self-report structured questionnaire at the Portuguese Public Bank of Gametes (response rate: 76%). Agreement with dual consent was defined as the belief that the use of EGDs in research should be consented by both donors and recipients. Results The majority of participants (74.6% of donors and 65.7% of recipients) were willing to donate embryos for research. Almost half of the donors (48.6%) and half of the recipients (46.9%) considered that a dual consent procedure is desirable. This view was more frequent among employed recipients (49.7%) than among non-employed (21.4%). Donors were less likely to believe that only recipients should be involved in giving consent for the use of EGDs in research (25.0% vs. 41.7% among recipients) and were more frequently favourable to the idea of exclusive donors' consent (26.4% vs. 11.4% among recipients). Conclusions Divergent views on dual consent among donors and recipients indicate the need to develop evidence-based and ethically sustainable policies and guidelines to protect well-being, autonomy and reproductive rights of both stakeholder groups. More empirical research and further theoretical normative analyses are needed to inform people-centred policy and guidelines for shared decision-making concerning the use of EGDs for research
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