13,148 research outputs found
The linear preservers of non-singularity in a large space of matrices
Let K be an arbitrary (commutative) field, and V be a linear subspace of
M_n(K) such that codim V<n-1. Using a recent generalization of a theorem of
Atkinson and Lloyd, we show that every linear embedding of V into M_n(K) which
strongly preserves non-singularity must be M->PMQ or M->PM^TQ for some pair
(P,Q) of non-singular matrices of M_n(K), unless n=3, codim V=1 and K is
isomorphic to F_2. This generalizes a classical theorem of Dieudonn\'e with a
similar strategy of proof. Weak linear preservers are also discussed, as well
as the exceptional case of a hyperplane of M_3(F_2).Comment: 35 pages (v4: added some additional explanations
On the matrices of given rank in a large subspace
Let V be a linear subspace of M_{n,p}(K) with codimension lesser than n,
where K is an arbitrary field and n >=p. In a recent work of the author, it was
proven that V is always spanned by its rank p matrices unless n=p=2 and K is
isomorphic to F_2. Here, we give a sufficient condition on codim V for V to be
spanned by its rank r matrices for a given r between 1 and p-1. This involves a
generalization of the Gerstenhaber theorem on linear subspaces of nilpotent
matrices.Comment: 8 page
Screening the genome to detect an association with hypertension
We report tree-based association analysis as applied to the two Framingham cohorts and to the first replication of the simulated data obtained from the Genetic Analysis Workshop 13. For this analysis, familial association is ignored. The two endpoints examined are hypertension status at initial visit and time-to-hypertension, using a censored data approach. Although linkage association has previously been reported with hypertension, we found no association using the tree-based methodology
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Bump start needed: linking guidelines, policy and practice in promoting physical activity during and beyond pregnancy
First paragraph: There is compelling evidence that regular physical activity (PA) during pregnancy benefits both mother and baby.1 2 Notably, physical and psychological benefits are evident in the literature, such as marked reductions in the development of gestational diabetes and hypertensive disorders, alongside improvements in depressive symptoms and cardiorespiratory fitness.1 2 The evidence base has been reflected by recent policy initiatives, for example, in 2017 (relaunched in 2019), the UKâs chief medical officers (CMOs) published PA guidelines for pregnant women, which made substantial strides in unifying and translating the evidence into recommendations.1 The CMO guidelines are aimed at supporting health professionals to provide consistent, evidence-based PA messages to women throughout pregnancy.1 Recently, the Chartered Institute for the Management of Sport and Physical Activity have updated their professional standards for working with antenatal and postnatal clients to align with these CMO guidelines.3 However, not all women have access to professionals with this level of expertise and training, potentially limiting the impact of the CMO guidelines
Effect of Interband Transitions on the c axis Penetration Depth of Layered Superconductors
The electromagnetic response of a system with two planes per unit cell
involves, in addition to the usual intraband contribution, an added interband
term. These transitions affect the temperature dependence and the magnitude of
the zero temperature c-axis penetration depth. When the interplane hopping is
sufficiently small, the interband transitions dominate the low temperature
behaviour of the penetration depth which then does not reflect the linear
temperature dependence of the intraband term and in comparison becomes quite
flat even for a d-wave gap. It is in this regime that the pseudogap was found
in our previous normal state calculations of the c-axis conductivity, and the
effects are connected.Comment: 8 pages, 5 figure
On the precision of chiral-dispersive calculations of scattering
We calculate the combination (the Olsson sum rule)
and the scattering lengths and effective ranges , and ,
dispersively (with the Froissart--Gribov representation) using, at
low energy, the phase shifts for scattering obtained by Colangelo,
Gasser and Leutwyler (CGL) from the Roy equations and chiral perturbation
theory, plus experiment and Regge behaviour at high energy, or directly, using
the CGL parameters for s and s. We find mismatch, both among the CGL
phases themselves and with the results obtained from the pion form factor. This
reaches the level of several (2 to 5) standard deviations, and is essentially
independent of the details of the intermediate energy region ( GeV) and, in some cases, of the high energy behaviour assumed. We discuss
possible reasons for this mismatch, in particular in connection with an
alternate set of phase shifts.Comment: Version to appear in Phys. Rev. D. Graphs and sum rule added. Plain
TeX fil
Phase shifts as functions of the cross section
We show that an elastic scattering amplitute may be defined as an implicit function of the differential cross section. A practical method is given for a numerical investigation of this dependence, both in the elastic and in the inelastic regions. In particular, we consider the case of a polynomial amplitude, and we show that the Crichton ambiguity is not isolated
Multinet : enabler for next generation enterprise wireless services
Wireless communications are currently experiencing a fast migration toward the beyond third-generation (B3G)/fourth generation (4G) era. This represents a generational change in wireless systems: new capabilities related to mobility and new services support is required and new concepts as individual-centric, user-centric or ambient-aware communications are included. One of the main restrictions associated to wireless technology is mobility management, this feature was not considered in the design phase; for this reason, a complete solution is not already found, although different solutions are proposed and are being proposed. In MULTINET project, features as mobility and multihoming are applied to wireless network to provide the necessary network and application functionality enhancements for seamless data communication mobility considering end-user scenario and preferences. The aim of this paper is to show the benefits of these functionalities from the Service Providers and final User point of view
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Offering weight management support to pregnant women with high body mass index: A qualitative study with midwives
Objective: The prevalence of pregnant women with high body mass index is increasing worldwide. High body mass index is associated with health risks for mother and baby and supporting healthy gestational weight gain is important. Midwives play an important role in supporting women to engage in behaviours such as healthy eating and physical activity. The aim of this study was to explore how midwivesâ support pregnant women with high body mass index to establish a healthy lifestyle with emphasis on nutrition and physical activity in order to minimise gestational weight gain.
Methods: Semi-structured interviews were conducted with 16 midwives working in antenatal health care in Sweden. Interviews were conducted shortly after new guidelines on care for pregnant women with high body mass index had been introduced. The interviews were recorded, transcribed and analysed by thematic analysis.
Results: Three main themes were identified; use a conscious approach, invite to participate and have a long-term health perspective. Midwives built a relationship with a woman through identifying her concerns and circumstances, before sensitively discussing weight. Some midwives used Motivational Interviewing to help women identify their own resources. To reach long-term health benefits, midwives set achievable goals with the women.
Conclusion: These study findings provide practical examples of how midwives can support women with weight management during pregnancy. Through being sensitive when developing a relationship, midwives enabled the women to identify their own resources and achievable goals. Support after the baby is born is needed subsequently to help women maintain their healthy behaviour changes
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