653 research outputs found
Hopf-cyclic cohomology of the Connes-Moscovici Hopf algebras with infinite dimensional coefficients
We discuss a new strategy for the computation of the Hopf-cyclic cohomology
of the Connes-Moscovici Hopf algebra . More precisely, we
introduce a multiplicative structure on the Hopf-cyclic complex of
, and we show that the van Est type characteristic homomorphism
from the Hopf-cyclic complex of to the Gelfand-Fuks cohomology
of the Lie algebra of formal vector fields on respects
this multiplicative structure. We then illustrate the machinery for .Comment: Minor revisions to highlight the main result
Polycrystalline materials with pores: effective properties through a boundary element homogenization scheme
In this study, the influence of porosity on the elastic effective properties of polycrystalline
materials is investigated using a formulation built on a boundary integral representation of the elastic
problem for the grains, which are modeled as 3D linearly elastic orthotropic domains with arbitrary spatial
orientation. The artificial polycrystalline morphology is represented using 3D Voronoi tessellations. The
formulation is expressed in terms of intergranular fields, namely displacements and tractions that play an
important role in polycrystalline micromechanics. The continuity of the aggregate is enforced through
suitable intergranular conditions. The effective material properties are obtained through material
homogenization, computing the volume averages of micro-strains and stresses and taking the ensemble
average over a certain number of microstructural samples. In the proposed formulation, the volume fraction
of pores, their size and distribution can be varied to better simulate the response of real porous materials. The
obtained results show the capability of the model to assess the macroscopic effects of porosity
Application of dual boundary element method in active sensing
In this paper, a boundary element method (BEM) for the dynamic analysis of 3D solid structures with bonded piezoelectric transducers is presented. The host structure is modelled with BEM and the piezoelectric transducers are formulated using a 3D semi-analytical finite element approach. The elastodynamic analysis of the entire structure is carried out in Laplace domain and the response in time domain is obtained by inverse Laplace transform. The BEM is validated against established finite element method (FEM)
Porosity effects on elastic properties of polycrystalline materials: a three-dimensional grain boundary formulation
Polycrystalline materials are widely used in many technological applications of engineering interest. They constitute an important class of heterogeneous materials, and the investigation of the link between their macro and micro properties, main task of the micromechanics [1], is of relevant technological concern. The internal structure of a polycrystalline material is determined by the size and the shape of the grains, by their crystallographic orientation and by different type of defects within them. In this sense, the presence of internal voids, pores, is important to take into account in the determination of the polycrystalline aggregate properties.
Porosity exists in almost all materials to some extent and in particular in the polycrystalline ones; it is strictly depending by the conditions in which their construction techniques are set. However, sometimes it is desired for other than structural reasons such us, for example, heat transfer properties, radar reflection etc. For this reason the effects of porosity should be of concern to any polycrystalline material developed for a design. In particular, the macroscopic effects of the pores on polycrystalline materials elastic properties is of high interest and the Young and shear modulus are the major parameter to analyze in this case.
In this study the influence of porosity presence on the elastic proprieties of polycrystalline materials is investigated and a 3D grain boundary micro mechanical model for the analysis of porosity in polycrystalline materials is used [2]. Therefore, the volume fraction of porosity, pore size and their distribution can be varied to better simulate the response of a real porous materials to a given load. The formulation is built on a boundary integral representation of the elastic problem for the single grain, that is modelled as 3D linearly elastic orthotropic domain with arbitrary spatial orientation. The artificial polycrystalline morphology is represented using the Voronoi Tessellation. This algorithms, in fact, is widely recognised and used for the generation of microstructural model and it is simple to generate the statistical features of polycrystalline microstructures. The formulation is expressed in terms of intergranular fields, namely displacement and traction that play an important role in polycrystalline micromechanics
A boundary element model for structural health monitoring using piezoelectric transducers
In this paper, for the first time, the boundary element method (BEM) is used for modelling
smart structures instrumented with piezoelectric actuators and sensors. The host structure and
its cracks are formulated with the 3D dual boundary element method (DBEM), and the
modelling of the piezoelectric transducers implements a 3D semi-analytical finite element
approach. The elastodynamic analysis of the structure is performed in the Laplace domain and
the time history is obtained by inverse Laplace transform. The sensor signals obtained from
BEM simulations show excellent agreement with those from finite element modelling
simulations and experiments. This work provides an alternative methodology for modelling
smart structures in structural health monitoring applications
Dual Boundary Element Method for fatigue crack growth: implementation of the Richard\u2019s criterion
A new criterion for fatigue crack growth, whose accuracy was previously tested in the literature with the Finite Element Method, is here adopted with a Dual Boundary Element formulation. The fatigue crack growth of an elliptical inclined crack, embedded in a three dimensional cylindrical bar, is analyzed. In this way in addition to the propagation angle estimated by the Sih\u2019s criterion, it is possible to take into account a twist propagation angle. The two propagation criteria are compared in terms of shape of the propagated crack and in terms of SIFs along the crack front. The efficiency of the Dual Boundary Element Method in this study is highlighted
Comparison of motor development of low birth weight (LBW) infants with and without using mechanical ventilation and normal birth weight infants
Background: To determine whether using mechanical ventilation in neonatal intensive care unit (NICU) influences motor development of low birth weight (LBW) infants and to compare their motor development with normal birth weight (NBW) infants at the age of 8 to 12 months using Peabody Developmental Motor Scale 2 (PDMS-2). Methods: This cross sectional study was conducted on 70 LBW infants in two groups, mechanical ventilation (MV) group, n=35 and without mechanical ventilation (WMV) group, n=35 and 40 healthy NBW infants matched with LBW group for age. Motor quotients were determined using PDMS-2 and compared in all groups using ANOVA statistical method and SPSS version 17. Results: Comparison of the mean developmental motor quotient (DMQ) of both MV and WMV groups showed significant differences with NBW group (p< 0.05). Also, significant difference was found between the gross DMQ of MV group and WMV group (p< 0.05). Moreover, in MV group, both gross and fine motor quotients were considered as below average (16.12). In WMV group, the gross motor quotient was considered as average (49.51) and the fine motor quotient was considered as below average (16.12). Conclusion: It seems that LBW infants have poor fine motor outcomes. The gross motor outcomes, on the other hand, will be significantly more influenced by using mechanical ventilation. In addition, more differences seem to be related to lower birth weight. Very Low Birth Weight (VLBW) infants are more prone to developmental difficulties than LBW infants with the history of using mechanical ventilation especially in fine motor development
Lived Experience of Caregivers of Family-Centered Care in the Neonatal Intensive Care Unit: “Evocation of Being at Home
Background: In recent decades, family-centered care (FCC) has come to be known, accepted, and reported as the best care strategy
for admitted children and their families. However, in spite of the increasing application of this approach, the experiences of the
caregivers have not yet been studied.
Objectives: The present study aimed at the description and interpretation of the FCC experience in two neonatal intensive care
units (NICU) at Shiraz University of Medical Sciences.
Methods: This study was conducted through the hermeneutic phenomenological approach. Semi-structured interviews were conducted
with 17 professional and familial caregivers, and their interactions were observed in three work shifts. The interviews were
audiotaped and transcribed verbatim. After observations, field notes were also written. Finally, the data were analyzed through van
Manen’s methodology.
Results: One of the essential themes that emerged in this study was the “evocation of being at home” among familial and even professional
caregivers. This theme had three subthemes: i.e., “meta-family interaction,” “comprehensive support,” and “reconstruction
of a normal family.” Accordingly, FCC eliminated borders between professional and non-professional caregivers and built close
relationships among them in the NICU. It also provided for the needs of neonates, their families, and even professional caregivers
through perceived and received support.
Conclusions: Parents of the neonates admitted to the NICU experience hard moments. They not only play the role of primary caregivers,
but they also receive the care. Focusing on the different meanings of this care from the caregivers’ points of view and having
managers provide certain requirements can guarantee the establishment of comprehensive care for clients and proper support for
the staff in this uni
Effects Aerosol of Industrial Bleach and Detergent Mixture on Mucosa Layer and Lamina Mucosa Conjunctiva in Mice
Today bleach and detergents are being frequently used and some people use their mixture for more cleaning. Because of chemical interaction of bleach and detergent, chlorine gas was released and thereby it could be dangerous for human health. This study examined the effects of exposed toxic mixture of bleach and detergent on the Mucosa layer and Lamina mucosa conjunctiva in the mice. In this study, 42 adult male mice NMRI race weighing 35-40 gr and from age 8 to 10 weeks were divided into 6 experimental groups and one control group. Experimental groups 1-2-3 with the use of chamber, the exposed 20 minutes were exposed to spray the amount 1 cc of mixture of bleach and detergent by nebulizer. Experimental groups 4-5-6 were for 35 minutes to inhale the same amount of material. Mice killed at 24-48-72 hours after exposed and the MucosaLayer and Lamina mucosa conjunctiva tissue was studied pathology. In the study of microscopic sections prepared of mouse mucosa layer and Lamina mucosa conjunctiva tissue experimental group comparison with the control group, significant decrease was observed in mucosa layer the have (p ≤ 0.001) and significant decrease was observed in the Lamina mucosa have(p ≤ 0. 01, p ≤ 0.001). As a result, increasing the exposed time of mixing bleach and detergent, as time passed, increasing the tissue damage and changes
Metabolic analysis of the interaction between plants and herbivores
Insect herbivores by necessity have to deal with a large arsenal of plant defence metabolites. The levels of defence compounds may be increased by insect damage. These induced plant responses may also affect the metabolism and performance of successive insect herbivores. As the chemical nature of induced responses is largely unknown, global metabolomic analyses are a valuable tool to gain more insight into the metabolites possibly involved in such interactions. This study analyzed the interaction between feral cabbage (Brassica oleracea) and small cabbage white caterpillars (Pieris rapae) and how previous attacks to the plant affect the caterpillar metabolism. Because plants may be induced by shoot and root herbivory, we compared shoot and root induction by treating the plants on either plant part with jasmonic acid. Extracts of the plants and the caterpillars were chemically analysed using Ultra Performance Liquid Chromatography/Time of Flight Mass Spectrometry (UPLCT/MS). The study revealed that the levels of three structurally related coumaroylquinic acids were elevated in plants treated on the shoot. The levels of these compounds in plants and caterpillars were highly correlated: these compounds were defined as the ‘metabolic interface’. The role of these metabolites could only be discovered using simultaneous analysis of the plant and caterpillar metabolomes. We conclude that a metabolomics approach is useful in discovering unexpected bioactive compounds involved in ecological interactions between plants and their herbivores and higher trophic levels.
- …
