662 research outputs found
Top dimensional group of the basic intersection cohomology for singular riemannian foliations
It is known that, for a regular riemannian foliation on a compact manifold,
the properties of its basic cohomology (non-vanishing of the top-dimensional
group and Poincar\'e Duality) and the tautness of the foliation are closely
related. If we consider singular riemannian foliations, there is little or no
relation between these properties. We present an example of a singular
isometric flow for which the top dimensional basic cohomology group is
non-trivial, but its basic cohomology does not satisfy the Poincar\'e Duality
property. We recover this property in the basic intersection cohomology. It is
not by chance that the top dimensional basic intersection cohomology groups of
the example are isomorphic to either 0 or . We prove in this Note
that this holds for any singular riemannian foliation of a compact connected
manifold. As a Corollary, we get that the tautness of the regular stratum of
the singular riemannian foliation can be detected by the basic intersection
cohomology.Comment: 11 pages. Accepted for publication in the Bulletin of the Polish
Academy of Science
Trends in Unwanted Online Experiences and Sexting : Final Report
This bulletin summarizes findings from the Third Youth Internet Safety Survey (YISS‐3). Topics include youth reports of unwanted sexual solicitations, online harassment, unwanted exposure to sexual material, and “sexting.
Finite temperature QMC study of the one-dimensional polarized Fermi gas
Quantum Monte Carlo (QMC) techniques are used to provide an
approximation-free investigation of the phases of the one-dimensional
attractive Hubbard Hamiltonian in the presence of population imbalance. The
temperature at which the "Fulde-Ferrell-Larkin-Ovchinnikov" (FFLO) phase is
destroyed by thermal fluctuations is determined as a function of the
polarization. It is shown that the presence of a confining potential does not
dramatically alter the FFLO regime, and that recent experiments on trapped
atomic gases likely lie just within the stable temperature range.Comment: 10 pages, 13 figures We added a discussion of the behaviour of the
FFLO peak as a function of the attractive interaction strengt
Pair formation and collapse in imbalanced Fermion populations with unequal masses
We present an exact Quantum Monte Carlo study of the effect of unequal masses
on pair formation in Fermionic systems with population imbalance loaded into
optical lattices. We have considered three forms of the attractive interaction
and find in all cases that the system is unstable and collapses as the mass
difference increases and that the ground state becomes an inhomogeneous
collapsed state. We also address the question of canonical vs grand canonical
ensemble and its role, if any, in stabilizing certain phases
Validation of polish version of the Basel extent of rationing of nursing care revised questionnaire
Development of simple, valid and reliable instruments to determine nursing care rationing is a subject of ongoing research. One such instrument, which is gaining popularity worldwide and has significant research applicability, is the Basel Extent of Rationing of Nursing Care (BERNCA) and its revised version, the BERNCA-R. The aim of this study was to translate and adapt the BERNCA-R into a Polish-language version and to assess its reliability and validity in evaluating the level of implicit rationing of nursing care in Poland. Standard methodological requirements were followed during translation and cultural adaptation of the English version of the BERNCA-R questionnaire into Polish. The cross-sectional validation study was conducted between May and September 2017, which included 175 nurses undergoing specialisation and qualification courses at the European Postgraduate Education Centre in Wrocław, Poland. Cronbach’s alpha and inter-item correlations were used to analyse the internal consistency of the Polish BERNCA-R questionnaire. The mean total BERNCA-R score was 1.9 points (SD = 0.74) on a scale of 0-4. Cronbach’s alpha for the unidimensional scale was 0.96. The mean inter-item correlation was 0.4 (range 0.1-0.84), which indicates high internal consistency. A single-factor solution demonstrated stable loadings above 0.5 for almost all items of the Polish BERNCA-R questionnaire. The study using the Polish BERNCA-R questionnaire demonstrated that the instrument is valid and reliable for use in investigating care rationing in groups of Polish nurses
Molten Salt Thermal Energy Storage Systems
The feasibility of storing thermal energy at temperatures of 450 C to 535 C in the form of latent heat of fusion was examined for over 30 inorganic salts and salt mixtures. Alkali carbonate mixtures were chosen as phase-change storage materials in this temperature range because of their relatively high storage capacity and thermal conductivity, moderate cost, low volumetric expansion upon melting, low corrosivity, and good chemical stability. Means of improving heat conduction through the solid salt were explored
Cohomological tautness for Riemannian foliations
In this paper we present some new results on the tautness of Riemannian
foliations in their historical context. The first part of the paper gives a
short history of the problem. For a closed manifold, the tautness of a
Riemannian foliation can be characterized cohomologically. We extend this
cohomological characterization to a class of foliations which includes the
foliated strata of any singular Riemannian foliation of a closed manifold
Reduction of Healthcare-Associated Infections by Exceeding High Compliance with Hand Hygiene Practices
Improving hand hygiene from high to very high compliance has not been documented to decrease healthcare-associated infections. We conducted longitudinal analyses during 2013–2015 in an 853-bed hospital and observed a significantly increased hand hygiene compliance rate (p<0.001) and a significantly decreased healthcare-associated infection rate (p = 0.0066)
“It’s like my life but more, and better!” - Playing with the Cathaby Shark Girls: MMORPGs, young people and fantasy-based social play
This article is available open access through the publisher’s website at the link below. Copyright @ 2011 A B Academic Publishers.Digital technology has opened up a range of new on-line leisure spaces for young people. Despite their popularity, on-line games and Massive Multiplayer Online Role Playing Games in particular are still a comparatively under-researched area in the fields of both Education and more broadly Youth Studies. Drawing on a Five year ethnographic study, this paper considers the ways that young people use the virtual spaces offered by MMORPGs. This paper suggests that MMORPGs represent significant arenas within which young people act out a range of social narratives through gaming. It argues that MMORPG have become important fantasy spaces which offer young people possibilities to engage in what were formally material practices. Although this form of play is grounded in the everyday it also extends material practices and offers new and unique forms of symbolic experimentation, thus I argue that game-play narratives cannot be divorced from the everyday lives of their participants
Tautness for riemannian foliations on non-compact manifolds
For a riemannian foliation on a closed manifold , it is
known that is taut (i.e. the leaves are minimal submanifolds) if
and only if the (tautness) class defined by the mean curvature form
(relatively to a suitable riemannian metric ) is zero. In the
transversally orientable case, tautness is equivalent to the non-vanishing of
the top basic cohomology group , where n = \codim
\mathcal{F}. By the Poincar\'e Duality, this last condition is equivalent to
the non-vanishing of the basic twisted cohomology group
, when is oriented. When is
not compact, the tautness class is not even defined in general. In this work,
we recover the previous study and results for a particular case of riemannian
foliations on non compact manifolds: the regular part of a singular riemannian
foliation on a compact manifold (CERF).Comment: 18 page
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