Properties of 3-manifolds for relativists

In canonical quantum gravity certain topological properties of 3-manifolds are of interest. This article gives an account of those properties which have so far received sufficient attention, especially those concerning the diffeomorphism groups of 3-manifolds. We give a summary of these properties and list some old and new results concerning them. The appendix contains a discussion of the group of large diffeomorphisms of the $l$-handle 3-manifold.Comment: 20 pages. Plain-TeX, no figures, 1 Table (A4 format

State space c-reductions for concurrent systems in rewriting logic

We present c-reductions, a state space reduction technique. The rough idea is to exploit some equivalence relation on states (possibly capturing system regularities) that preserves behavioral properties, and explore the induced quotient system. This is done by means of a canonizer function, which maps each state into a (non necessarily unique) canonical representative of its equivalence class. The approach exploits the expressiveness of rewriting logic and its realization in Maude to enjoy several advantages over similar approaches: exibility and simplicity in the definition of the reductions (supporting not only traditional symmetry reductions, but also name reuse and name abstraction); reasoning support for checking and proving correctness of the reductions; and automatization of the reduction infrastructure via Maude's meta-programming features. The approach has been validated over a set of representative case studies, exhibiting comparable results with respect to other tools

Model-based Aeroservoelastic Design and Load Alleviation of Large Wind Turbine Blades

This paper presents an aeroservoelastic modeling approach for dynamic load alleviation in large wind turbines with trailing-edge aerodynamic surfaces. The tower, potentially on a moving base, and the rotating blades are modeled using geometrically non-linear composite beams, which are linearized around reference conditions with arbitrarily-large structural displacements. Time-domain aerodynamics are given by a linearized 3-D unsteady vortexlattice method and the resulting dynamic aeroelastic model is written in a state-space formulation suitable for model reductions and control synthesis. A linear model of a single blade is used to design a Linear-Quadratic-Gaussian regulator on its root-bending moments, which is finally shown to provide load reductions of about 20% in closed-loop on the full wind turbine non-linear aeroelastic model

Quantitative measurement of sliding friction dynamics at mesoscopic scales: The lateral force apparatus

We describe an apparatus designed to quantitatively measure friction dynamics at the mesoscopic scale. This lateral force apparatus, LFA, uses double parallel leaf springs in leaf-spring units as force transducers and two focus error detection optical heads, optical heads, to measure deflections. The design of the leaf-spring units is new. Normal spring constants are in the range of 20–4000 N/m, and lateral spring constants are 7–1000 N/m. The optical heads combine a 10 nm sensitivity with a useful range of about 100 µm. The proven range of normal forces is 400 nN–150 mN. The leaf-spring units transduce friction and normal forces independently. Absolute values of normal and friction forces are calibrated. Typical errors are less than 10%. The calibration is partly in situ, for the sensitivity of the optical heads, and partly ex situ for the normal and lateral spring constants of the leaf-spring units. There is minimal coupling between the deflection measurements in the lateral and normal directions. This coupling is also calibrated in situ. It is typically 1% and can be as low as 0.25%. This means that the displacements of the tip can be measured accurately in the sliding direction and normal to the surface. Together, these characteristics make the LFA, well suited for quantitative study of friction dynamics at mesoscopic scales. Furthermore the design of the leaf-spring unit allows exchange of tips which may be fabricated (e.g., etched) from wire material (d0.4 mm) and can have customized shapes, e.g., polished flat squares. The ability of the LFA to study friction dynamics is briefly illustrated by results of stick-slip measurements on soft polymer surfaces

An Analysis of the Representations of the Mapping Class Group of a Multi-Geon Three-Manifold

It is well known that the inequivalent unitary irreducible representations (UIR's) of the mapping class group $G$ of a 3-manifold give rise to ``theta sectors'' in theories of quantum gravity with fixed spatial topology. In this paper, we study several families of UIR's of $G$ and attempt to understand the physical implications of the resulting quantum sectors. The mapping class group of a three-manifold which is the connected sum of $\R^3$ with a finite number of identical irreducible primes is a semi-direct product group. Following Mackey's theory of induced representations, we provide an analysis of the structure of the general finite dimensional UIR of such a group. In the picture of quantized primes as particles (topological geons), this general group-theoretic analysis enables one to draw several interesting qualitative conclusions about the geons' behavior in different quantum sectors, without requiring an explicit knowledge of the UIR's corresponding to the individual primes.Comment: 52 pages, harvmac, 2 postscript figures, epsf required. Added an appendix proving the semi-direct product structure of the MCG, corrected an error in the characterization of the slide subgroup, reworded extensively. All our analysis and conclusions remain as befor

The general public's perceptions of how the COVID-19 pandemic has impacted the elderly and individuals with intellectual disabilities

This study examined the general public’s perceptions of how the COVID-19 pandemic has impacted the elderly and people with intellectual disabilities as well how these perceptions relate to people’s level of familiarity and contact quality with these groups. A cross-sectional survey was administered to a sample of the Dutch population (n = 1458 and n = 1761, comprising questions related to the elderly and people with intellectual disabilities, respectively). The general public was found to be generally aware of the deleterious impact of the pandemic upon the elderly and people with intellectual disabilities. Specifically, the respondents reported that both groups’ quality of life, physical and mental health, and quality and frequency of social contact was lower than it was prior to COVID-19, in addition to perceiving them as lonelier and less self-reliant. Notably, the impact on the elderly was considered to be greater than that on people with intellectual disabilities. Furthermore, those who had no familiarity with people with intellectual disabilities in real life perceived the impact to be lower than those who had a greater degree of familiarity. These findings have important implications, both for increasing awareness of the pandemic’s negative impact on these vulnerable groups and in terms of sufficiently addressing their specific needs and concerns. The findings also underscore that, particularly during the COVID-19 pandemic, it is important to increase the visibility of groups who already relied more on help and support from others in society prior to the pandemic, such as the elderly and people with intellectual disabilities, via, among other things, self-advocacy, education, and enhanced intergroup contact, in order to be able to sufficiently address their needs during these challenging times

Highly polymorphic microsatellite markers for the Mediterranean endemic fan mussel Pinna nobilis

Pinna nobilis is an endemic bivalve of the Mediterranean Sea whose populations have decreased in the last decades due to human pressure; as a consequence, it was declared a protected species in 1992. Despite its conservation status, few genetic studies using mitochondrial markers have been published. We report on the isolation and development of 10 microsatellite loci for the fan mussel, Pinna nobilis. All loci (2 di-nucleotide, 5 tri-nucleotide, 2 tetra-nucleotide and 1 penta-nucleotide) are characterized by high levels of polymorphism in 76 individuals tested from two populations in the Balearic Islands (Spain, Western Mediterranean Sea). The number of alleles ranged from 4 to 24 and expected heterozygosity ranged from 0.4269 to 0.9400. These microsatellites could be very useful for the assessment of the genetic diversity and connectivity patterns of P. nobilis and the establishment of new conservation strategies

Is personality a determinant of patient satisfaction with hospital care?

Objective. We investigated to what extent personality is associated with patient satisfaction with hospital care. A sizeable association with personality would render patient satisfaction invalid as an indicator of hospital care quality. Design. Overall satisfaction and satisfaction with aspects of care were regressed on the Big Five dimensions of personality, controlled for patient characteristics as possible explanatory variables of observed associations. Participants. A total of 237 recently discharged inpatients aged 18-84 years (M = 50, SD = 17 years), 57% female, who were hospitalized for an average of 8 days. Instruments. The Satisfaction with Hospital Care Questionnaire addressing 12 aspects of care ranging from admission procedures to discharge and aftercare and the Five-Factor Personality Inventory assessing a person's standing on Extraversion, Agreeableness, Conscientiousness, Emotional stability, and Autonomy. Results. Agreeableness significantly predicted patient satisfaction in about half of the scales. After controlling for shared variance with age and educational level, the unique contribution of Agreeableness shrank to a maximum of 3-5% explained variance. When one outlier was dropped from the analysis, the contribution of Agreeableness was no longer statistically significant. Conclusion. Patient satisfaction seems only marginally associated with personality, at least at the level of the broad Big Five dimension