10,074 research outputs found
Challenges encountered during acid resin transfer preparation of fossil fish from Monte Bolca, Italy
Copyright: Palaeontological Association May 2015.
This is an open access article, available to all readers online, published under a creative commons licensing (https://creativecommons.org/licenses/by/4.0/). The file attached is the published version of the article
A Morse index theorem for elliptic operators on bounded domains
Given a selfadjoint, elliptic operator , one would like to know how the
spectrum changes as the spatial domain is
deformed. For a family of domains we prove that the
Morse index of on differs from the Morse index of on
by the Maslov index of a path of Lagrangian subspaces on the
boundary of . This is particularly useful when is a domain
for which the Morse index is known, e.g. a region with very small volume. Then
the Maslov index computes the difference of Morse indices for the "original"
problem (on ) and the "simplified" problem (on ). This
generalizes previous multi-dimensional Morse index theorems that were only
available on star-shaped domains or for Dirichlet boundary conditions. We also
discuss how one can compute the Maslov index using crossing forms, and present
some applications to the spectral theory of Dirichlet and Neumann boundary
value problems.Comment: 21 pages; weaker regularity assumptions than in the first versio
The Regulation of Aggrecanase ADAMTS-4 Expression in Human Achilles Tendon and tendon-Derived Cells
Several members of the ADAMTS (A Disintegrin And Metalloproteinase with ThromboSpondin motifs) family have been identified as aggrecanases, whose substrates include versican, the principal large proteoglycan in the tendon extracellular matrix. We have characterized the expression of ADAMTS-4 in human Achilles tendon and tendon-derived cells. ADAMTS-4 mRNA levels were higher in ruptured tendon compared with normal tendon or chronic painful tendinopathy. In tissue extracts probed by Western blotting, mature ADAMTS-4 (68 kDa) was detected only in ruptured tendons, while processed ADAMTS-4 (53 kDa) was detected also in chronic painful tendinopathy and in normal tendon. In cultured Achilles tendon cells, transforming growth factor-Ă (TGF-Ă) stimulated ADAMTS-4 mRNA expression (typically 20-fold after 24 h), while interleukin-1 induced a smaller, shorter-term stimulation which synergised markedly with that induced by TGF-Ă. Increased levels of immunoreactive proteins consistent with mature and processed forms of ADAMTS-4 were detected in TGF-Ă-stimulated cells. ADAMTS-4 mRNA was expressed at higher levels by tendon cells in collagen gels than in monolayer cultures. In contrast, the expression of ADAMTS-1 and -5 mRNA was lower in collagen gels compared with monolayers, and these mRNA showed smaller or opposite responses to growth factors and cytokines compared with that of ADAMTS-4 mRNA. We conclude that both ADAMTS-4 mRNA and ADAMTS-4 protein processing may be differentially regulated in normal and damaged tendons and that both the matrix environment and growth factors such as TGF-Ă are potentially important factors controlling ADAMTS aggrecanase activities in tendon pathology
Non-linear and quantum optics of a type II OPO containing a birefringent element Part 1: Classical operation
We describe theoretically the main characteristics of the steady state regime
of a type II Optical Parametric Oscillator (OPO) containing a birefringent
plate. In such a device the signal and idler waves are at the same time
linearly coupled by the plate and nonlinearly coupled by the
crystal. This mixed coupling allows, in some well-defined range of the control
parameters, a frequency degenerate operation as well as phase locking between
the signal and idler modes. We describe here a complete model taking into
account all possible effects in the system, \emph{i.e.} arbitrary rotation of
the waveplate, non perfect phase matching, ring and linear cavities. This model
is able to explain the detailed features of the experiments performed with this
system.Comment: To be published in EPJ
Simulations of Dense Atomic Hydrogen in the Wigner Crystal Phase
Path integral Monte Carlo simulations are applied to study dense atomic
hydrogen in the regime where the protons form a Wigner crystal. The interaction
of the protons with the degenerate electron gas is modeled by Thomas-Fermi
screening, which leads to a Yukawa potential for the proton-proton interaction.
A numerical technique for the derivation of the corresponding action of the
paths is described. For a fixed density of rs=200, the melting is analyzed
using the Lindemann ratio, the structure factor and free energy calculations.
Anharmonic effects in the crystal vibrations are analyzed.Comment: Proceedings article of the Study of Matter at Extreme Conditions
(SMEC) conference in Miami, Florida; submitted to Journal of Physics and
Chemistry of Solids (2005
Perspectives of Employed People Experiencing Homelessness of Self and Being Homeless: Challenging Socially Constructed Perceptions and Stereotypes
In a study that sought to identify the multiple factors resulting in homelessness from the perspective of 65 individuals in Calgary, Alberta, Canada who were both employed and homeless, we found that participants\u27 perceptions of being homeless emerged as a major theme which impacts their entry to and exit from homelessness. Four sub-themes related to these perceptions were identified: (1) perceptions of self and situation; (2) impact of being homeless on self-reflection; (3) aspects of hope to consider; and (4) perspectives on having a permanent residence. Analytically, these findings help challenge present stereotypes about homelessness and usefully inform social service delivery organizations
Optimising intervention implementation in the DCM (TM) epic trial (dementia care mapping (TM) : to enable person-centred care in care homes)
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Three-dimensional modeling of human placental terminal villi.
INTRODUCTION: Placental transport is the main factor affecting the health and development of the fetus. Due to the placenta's geometrical and mathematical complexity, the structure-function relations of placental terminal villi have not been successfully modeled. Hence, a novel modeling approach is proposed. METHODS: Computational models of four different specimens were generated from the three-dimensional reconstruction of confocal laser scanning microscopic image stacks. To evaluate the capabilities of the proposed methodology, stationary oxygen diffusion transport was calculated in the terminal villus volumes. RESULTS: The reconstructions automatically provided the spatial arrangement of the fetal capillaries inside the terminal villi. The surface and volume ratios between the fetal capillaries and the villus were also calculated, and the effects of model parameters on the placental diffusive capacity were assessed by parametric analysis. DISCUSSION: The potential of three-dimensional reconstructions combined with finite element analysis as a research tool for the human placenta was tested. The methodology herein could serve in the future as a simulation platform for complicated in vivo and in vitro scenarios.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.placenta.2016.05.00
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