On Automorphisms and Focal Subgroups of Blocks

Given a p-block B of a finite group with defect group P and fusion system on P, we show that the rank of the group is invariant under stable equivalences of Morita type. The main ingredients are the construction, due to Broué and Puig, a theorem of Weiss on linear source modules, arguments of Hertweck and Kimmerle applying Weiss’ theorem to blocks, and connections with integrable derivations in the Hochschild cohomology of block algebras

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Can we always get the entanglement entropy from the Kadanoff-Baym equations? The case of the T-matrix approximation

We study the time-dependent transmission of entanglement entropy through an out-of-equilibrium model interacting device in a quantum transport set-up. The dynamics is performed via the Kadanoff-Baym equations within many-body perturbation theory. The double occupancy $< \hat{n}_{R \uparrow} \hat{n}_{R \downarrow} >$, needed to determine the entanglement entropy, is obtained from the equations of motion of the single-particle Green's function. A remarkable result of our calculations is that $< \hat{n}_{R \uparrow} \hat{n}_{R \downarrow} >$ can become negative, thus not permitting to evaluate the entanglement entropy. This is a shortcoming of approximate, and yet conserving, many-body self-energies. Among the tested perturbation schemes, the $T$-matrix approximation stands out for two reasons: it compares well to exact results in the low density regime and it always provides a non-negative $< \hat{n}_{R \uparrow} \hat{n}_{R \downarrow} >$. For the second part of this statement, we give an analytical proof. Finally, the transmission of entanglement across the device is diminished by interactions but can be amplified by a current flowing through the system.Comment: 6 pages, 6 figure

Attitudes and practices of physicians and nurses regarding physical activity promotion in the Catalan primary health-care system

Background: In Catalonia a high percentage of the population remains inactive. General practices are an ideal setting to advise on physical activity (PA). However, there is a lack of evidence regarding practices, barriers and predictors of such promotion in the Catalan primary health-care system. This study set out to establish descriptive baseline data for PA promotion in Catalan general practices, and to explore the experiences of doctors/nurses in promoting PA in their day-to-day professional lives. Methods: A mixedmethod approach was adopted. A survey was conducted with 245 physicians/nurses (58% response rate). Subsequently, focus groups (n ¼ 5) and semi-structured interviews (n ¼ 7) were conducted with 18 physicians and 15 nurses. After coding for important themes, the final interpretation was confirmed by contributors. Results: Eighty-eight percent of physicians/nurses promoted PA at least infrequently. However, work conditions were perceived as unfavourable, with the main barriers being lack of (i) time, (ii) training and (iii) protocols. Qualitative data showed that PA promotion was opportunistic, focused on selected patients, used generalized messages and was highly dependent on personal interests. Regular promotion was encouraged by direct experiences of the benefits of regular exercising, knowing patients well, being supported by medical colleagues and creating links with other community institutions. PA promotion was especially hindered by seeing PA promotion as a secondary task, and patients ignoring recommendations. Conclusions: PA promotion in Catalonia remains to be integrated into practice consultations. Therefore, strategies should be developed within public health. Using a mixed-method approach provided a broader range of evidence than most studies, which rely on quantitative methods