Tools in the orbit space approach to the study of invariant functions: rational parametrization of strata

Functions which are equivariant or invariant under the transformations of a compact linear group $G$ acting in an euclidean space $\real^n$, can profitably be studied as functions defined in the orbit space of the group. The orbit space is the union of a finite set of strata, which are semialgebraic manifolds formed by the $G$-orbits with the same orbit-type. In this paper we provide a simple recipe to obtain rational parametrizations of the strata. Our results can be easily exploited, in many physical contexts where the study of equivariant or invariant functions is important, for instance in the determination of patterns of spontaneous symmetry breaking, in the analysis of phase spaces and structural phase transitions (Landau theory), in equivariant bifurcation theory, in crystal field theory and in most areas where use is made of symmetry adapted functions. A physically significant example of utilization of the recipe is given, related to spontaneous polarization in chiral biaxial liquid crystals, where the advantages with respect to previous heuristic approaches are shown.Comment: Figures generated through texdraw package; revised version appearing in J. Phys. A: Math. Ge

A note on Dolby and Gull on radar time and the twin "paradox"

Recently a suggestion has been made that standard textbook representations of hypersurfaces of simultaneity for the travelling twin in the twin "paradox" are incorrect. This suggestion is false: the standard textbooks are in agreement with a proper understanding of the relativity of simultaneity.Comment: LaTeX, 3 pages, 2 figures. Update: added new section V and updated reference

Embedding auxetic properties in designing active-bending gridshells

Advancements in computational tools are offering designers the possibility to change their relationship with materials. The exploration ofauxetic metamaterials, specifically engineered to obtain properties beyond those found in nature, is the promising field examined in this paper. The aim is to define tools and methods in order to design auxetics, and use them tocreate efficient active-bending structures. By programming their geometry through several parameters, it is possible to finely control curvature and structural resistance. The paper describes an original investigation into the process of programming such structures through the use of combined computational tools

Systemic Input-Output Computation of Green and Blue Virtual Water 'Flows' with an Illustration for the Mediterranean Region

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Study of the attitudes and future intentions of nursing students towards working with older people: an observational study

Background: Older people are increasing in the world leading to the fact that many nursing students will work in geriatric care setting. It was also reported the lack of knowledge and interest in working with older people by many nursing students. Therefore, the aim of the study is to explore the attitudes, wills, and intentions for the care of older people from nursing students. Methods: A sample of 383 students (mean age between 17 and 24; females: 76.2%) was divided according to the year. A questionnaire and three scales investigating the attitude for working with older persons (Kogan, Aday-Campbell, Nolan scales) were administered. Simple correlations across the three scales and the comparisons in means by year of graduation were reported. Results: Of the 383 students, 69.7% would take care of an older person, with the previous experience with older patients being the most important determinant in positive attitude of students in working with older people. The Kogan scale revealed a relatively positive attitude towards older people of the students involved; the Aday’s scale a reasonable willingness to take care of the older people; the Nolan scale a fair intention. Aday’s scale significantly correlated with Nolan’s scale and with Kogan’s scale as well as the Nolan scale correlated with the Kogan scale. Conclusion: Our study suggests that the quality of care provided to older people is related to the attitudes of health professionals indicating that nursing educators should adopt effective strategies to increase and promote students’ positive attitudes to older people. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG

Geometric invariant theory approach to the determination of ground states of D-wave condensates in isotropic space

A complete and rigorous determination of the possible ground states for D-wave pairing Bose condensates is presented, using a geometrical invariant theory approach to the problem. The order parameter is argued to be a vector, transforming according to a ten dimensional real representation of the group $G=${\bf O}$_3\otimes${\bf U}$_1\times$. We determine the equalities and inequalities defining the orbit space of this linear group and its symmetry strata, which are in a one-to-one correspondence with the possible distinct phases of the system. We find 15 allowed phases (besides the unbroken one), with different symmetries, that we thoroughly determine. The group-subgroup relations between bordering phases are pointed out. The perturbative sixth degree corrections to the minimum of a fourth degree polynomial $G$-invariant free energy, calculated by Mermin, are also determined.Comment: 27 revtex pages, 2 figures, use of texdraw; minor changes in the bibliography and in Table II

Matched filters for coalescing binaries detection on massively parallel computers

We discuss some computational problems associated to matched filtering of experimental signals from gravitational wave interferometric detectors in a parallel-processing environment. We then specialize our discussion to the use of the APEmille and apeNEXT processors for this task. Finally, we accurately estimate the performance of an APEmille system on a computational load appropriate for the LIGO and VIRGO experiments, and extrapolate our results to apeNEXT.Comment: 19 pages, 6 figure

Manejo reprodutivo da fêmea leiteira.

Edição dos anais do 27. Congresso Brasileiro de Reprodução Animal, 2007, Curitiba, PR