Infinite combinatorial issues raised by lifting problems in universal algebra

The critical point between varieties A and B of algebras is defined as the least cardinality of the semilattice of compact congruences of a member of A but of no member of B, if it exists. The study of critical points gives rise to a whole array of problems, often involving lifting problems of either diagrams or objects, with respect to functors. These, in turn, involve problems that belong to infinite combinatorics. We survey some of the combinatorial problems and results thus encountered. The corresponding problematic is articulated around the notion of a k-ladder (for proving that a critical point is large), large free set theorems and the classical notation (k,r,l){\to}m (for proving that a critical point is small). In the middle, we find l-lifters of posets and the relation (k, < l){\to}P, for infinite cardinals k and l and a poset P.Comment: 22 pages. Order, to appea

Sports Hall - Warranty Defect of Floor

The paper examines the issue of managing complaints after buildings have been put into operation. The problem is documented through the case study example “Sports Hall Reconstruction”, in which a fault appearing in part of a large concrete slab is described. The construction of large concrete slabs to form the base floor layers in sports and industrial buildings is often accompanied by numerous problems. Achieving an even structure in the final surface is one of the main problems on account of the large amounts of processed concrete used. Construction of the base layers beneath concrete floors using the materials prescribed by project documentation therefore demands considerable attention. Technological discipline in processing concrete mixtures in relation to potential shrinkage cracking or cracks caused by improperly installed expansion joints is an equally important part of industrial flooring construction

Generalized Vietoris Bisimulations

We introduce and study bisimulations for coalgebras on Stone spaces [14]. Our notion of bisimulation is sound and complete for behavioural equivalence, and generalizes Vietoris bisimulations [4]. The main result of our paper is that bisimulation for a $\mathbf{Stone}$ coalgebra is the topological closure of bisimulation for the underlying $\mathbf{Set}$ coalgebra

Occupational Physical Activity and Cardiovascular Risk Factors Profile in the Adult Population of the Southern Cone of Latin America: Results From the CESCAS I Study

OBJECTIVE: We explore the association between occupational physical activity (OPA) and cardiovascular risk factors in four cities of the Southern Cone. METHODS: Robust multivariable linear regression models were used to examine the associations. RESULTS: The working population was constituted by 1868 men and 1672 women. Men performing high levels of OPA showed higher levels of high-density lipoprotein (HDL; mean adj. diff. = 2.24 mg/dL; P = 0.004), lower levels of triglycerides (-24.59 mg/dL; P = 0.006), and total cholesterol (TC)/HDL ratio values (-0.21; P = 0.015) than reference. Women in the highest category of OPA had higher levels of HDL (2.85 mg/dL; P = 0.006), lower TC/HDL (0.27; P = 0.001), and low-density lipoprotein/HDL ratios (-0.18; P = 0.003) than sedentary activities. CONCLUSION: Individuals who performed high levels of OPA did not exhibit a worse cardiovascular risk profile and an improvement on selected biomarkers was observed when compared with those performing sedentary activities.Fil: Poggio, Rosana. Instituto de Efectividad Clínica y Sanitaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Melendi, Santiago Ezequiel. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Gutierrez, Laura. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Elorriaga, Natalia. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Irazola, Vilma. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto de Efectividad Clínica y Sanitaria; Argentin

Mechanical lifting energy consumption in work activities designed by means of the "revised NIOSH lifting equation"\u80\u9d

The aims of the present work were: to calculate lifting energy consumption (LEC) in work activities designed to have a growing lifting index (LI) by means of revised NIOSH lifting equation; to evaluate the relationship between LEC and forces at the L5-S1 joint. The kinematic and kinetic data of 20 workers were recorded during the execution of lifting tasks in three conditions. We computed kinetic, potential and mechanical energy and the corresponding LEC by considering three different centers of mass of: 1) the load (CoML); 2) the multi-segment upper body model and load together (CoMUpp+L); 3) the whole body and load together (CoMTot). We also estimated compression and shear forces. Results shows that LEC calculated for CoMUpp+L and CoMTot grew significantly with the LI and that all the lifting condition pairs are discriminated. The correlation analysis highlighted a relationship between LEC and forces that determine injuries at the L5-S1 joint

Derivative Chameleons

We consider generalized chameleon models where the conformal coupling between matter and gravitational geometries is not only a function of the chameleon field \phi, but also of its derivatives via higher order co-ordinate invariants. Specifically we consider the first such non-trivial conformal factor A(\phi,X), where X is the canonical kinetic term for \phi. The associated phenomenology is investigated and we show that such theories have a new generic mass-altering mechanism, potentially assisting the generation of a sufficiently large chameleon mass in dense environments. The most general effective potential is derived for such derivative chameleon setups and explicit examples are given. Interestingly this points us to the existence of a purely derivative chameleon protected by a shift symmetry for \phi. We also discuss potential ghost-like instabilities associated with mass-lifting mechanisms and find another, mass-lowering and instability-free, branch of solutions. This suggests that, barring fine-tuning, stable derivative models are in fact typically anti-chameleons that suppress the field's mass in dense environments. Furthermore we investigate modifications to the thin-shell regime and prove a no-go theorem for chameleon effects in non-conformal geometries of the disformal type.Comment: 28 pages, 4 figure