2,532 research outputs found
Evaluation of the efficacy of Alpron disinfectant for dental unit water lines
AIMS: To assess the efficacy of a disinfectant, Alpron, for controlling microbial contamination within dental unit water lines. METHODS: The microbiological quality of water emerging from the triple syringe, high speed handpiece, cup filler and surgery hand wash basin from six dental units was assessed for microbiological total viable counts at 22 degrees C and 37 degrees C before and after treatment with Alpron solutions. RESULTS: The study found that the use of Alpron disinfectant solutions could reduce microbial counts in dental unit water lines to similar levels for drinking water. This effect was maintained in all units for up to six weeks following one course of treatment. In four out of six units the low microbial counts were maintained for 13 weeks. CONCLUSIONS: Disinfectants may have a short term role to play in controlling microbial contamination of dental unit water lines to drinking water quality. However, in the longer term attention must be paid to redesigning dental units to discourage the build up of microbial biofilms
A cross sectional study of water quality from dental unit water lines in dental practices in the West of Scotland
OBJECTIVE: To determine the microbiological quality of water from dental units in a general practice setting and current practice for disinfection of units. DESIGN: A cross-sectional study of the water quality from 40 dental units in 39 general practices and a questionnaire of the disinfection protocols used in those practices. SETTING: NHS practices in primarydental care. SUBJECTS: Thirty-nine general practices from the West of Scotland. METHODS: Water samples were collected on two separate occasions from dental units and analysed for microbiological quality by the total viable count (TVC) method. Water specimens were collected from the triple syringe, high speed outlet, cup filler and surgery tap. Each participating practitioner was asked to complete a questionnaire. Results Microbial contamination was highest from the high speed outlet followed by the triple syringe and cup filler. On average, the TVC counts from the high speed water lines at 37 degrees C and for the high speed lines, triple syringe and cup filler at 22 degrees C were significantly higher than that from the control tap water specimens. The study included units from 11 different manufacturers with ages ranging from under one year to over eight years. The age of the dental unit analysed did not appear to influence the level of microbial contamination. Five of the practices surveyed used disinfectants to clean the dental units but these had no significant effect on the microbiological quality of the water. The majority of dental units (25 out of 40) were never flushed with water between patients. A number of different non-sterile irrigants were used for surgical procedures. CONCLUSION: The microbiological quality of water from dental units in general dental practice is poor compared with that from drinking water sources. Suitable sterile irrigants should be used for surgical procedures in dental practice. Further work is required for pragmatic decontamination regimens of dental unit water lines in a general dental practice setting
TGF-beta 1 induces human alveolar epithelial to mesenchymal cell transition (EMT)
Background: Fibroblastic foci are characteristic features in lung parenchyma of patients with idiopathic pulmonary fibrosis (IPF). They comprise aggregates of mesenchymal cells which underlie sites of unresolved epithelial injury and are associated with progression of fibrosis. However, the cellular origins of these mesenchymal phenotypes remain unclear. We examined whether the potent fibrogenic cytokine TGF-β1 could induce epithelial mesenchymal transition (EMT) in the human alveolar epithelial cell line, A549, and investigated the signaling pathway of TGF-β1-mediated EMT.
Methods: A549 cells were examined for evidence of EMT after treatment with TGF-β1. EMT was assessed by: morphology under phase-contrast microscopy; Western analysis of cell lysates for expression of mesenchymal phenotypic markers including fibronectin EDA (Fn-EDA), and expression of epithelial phenotypic markers including E-cadherin (E-cad). Markers of fibrogenesis, including collagens and connective tissue growth factor (CTGF) were also evaluated by measuring mRNA level using RT-PCR, and protein by immunofluorescence or Western blotting. Signaling pathways for EMT were characterized by Western analysis of cell lysates using monoclonal antibodies to detect phosphorylated Erk1/2 and Smad2 after TGF-β1 treatment in the presence or absence of MEK inhibitors. The role of Smad2 in TGF-β1-mediated EMT was investigated using siRNA.
Results: The data showed that TGF-β1, but not TNF-α or IL-1β, induced A549 cells with an alveolar epithelial type II cell phenotype to undergo EMT in a time-and concentration-dependent manner. The process of EMT was accompanied by morphological alteration and expression of the fibroblast phenotypic markers Fn-EDA and vimentin, concomitant with a downregulation of the epithelial phenotype marker E-cad. Furthermore, cells that had undergone EMT showed enhanced expression of markers of fibrogenesis including collagens type I and III and CTGF. MMP-2 expression was also evidenced. TGF-β1-induced EMT occurred through phosphorylation of Smad2 and was inhibited by Smad2 gene silencing; MEK inhibitors failed to attenuate either EMT-associated Smad2 phosphorylation or the observed phenotypic changes.
Conclusion: Our study shows that TGF-β1 induces A549 alveolar epithelial cells to undergo EMT via Smad2 activation. Our data support the concept of EMT in lung epithelial cells, and suggest the need for further studies to investigate the phenomenon
A topological classification of convex bodies
The shape of homogeneous, generic, smooth convex bodies as described by the
Euclidean distance with nondegenerate critical points, measured from the center
of mass represents a rather restricted class M_C of Morse-Smale functions on
S^2. Here we show that even M_C exhibits the complexity known for general
Morse-Smale functions on S^2 by exhausting all combinatorial possibilities:
every 2-colored quadrangulation of the sphere is isomorphic to a suitably
represented Morse-Smale complex associated with a function in M_C (and vice
versa). We prove our claim by an inductive algorithm, starting from the path
graph P_2 and generating convex bodies corresponding to quadrangulations with
increasing number of vertices by performing each combinatorially possible
vertex splitting by a convexity-preserving local manipulation of the surface.
Since convex bodies carrying Morse-Smale complexes isomorphic to P_2 exist,
this algorithm not only proves our claim but also generalizes the known
classification scheme in [36]. Our expansion algorithm is essentially the dual
procedure to the algorithm presented by Edelsbrunner et al. in [21], producing
a hierarchy of increasingly coarse Morse-Smale complexes. We point out
applications to pebble shapes.Comment: 25 pages, 10 figure
Searching for plasticity in dissociated cortical cultures on multi-electrode arrays
We attempted to induce functional plasticity in dense cultures of cortical cells using stimulation through extracellular electrodes embedded in the culture dish substrate (multi-electrode arrays, or MEAs). We looked for plasticity expressed in changes in spontaneous burst patterns, and in array-wide response patterns to electrical stimuli, following several induction protocols related to those used in the literature, as well as some novel ones. Experiments were performed with spontaneous culture-wide bursting suppressed by either distributed electrical stimulation or by elevated extracellular magnesium concentrations as well as with spontaneous bursting untreated. Changes concomitant with induction were no larger in magnitude than changes that occurred spontaneously, except in one novel protocol in which spontaneous bursts were quieted using distributed electrical stimulation
Rotating black holes with equal-magnitude angular momenta in d=5 Einstein-Gauss-Bonnet theory
We construct rotating black hole solutions in Einstein-Gauss-Bonnet theory in
five spacetime dimensions. These black holes are asymptotically flat, and
possess a regular horizon of spherical topology and two equal-magnitude angular
momenta associated with two distinct planes of rotation. The action and global
charges of the solutions are obtained by using the quasilocal formalism with
boundary counterterms generalized for the case of Einstein-Gauss-Bonnet theory.
We discuss the general properties of these black holes and study their
dependence on the Gauss-Bonnet coupling constant . We argue that most
of the properties of the configurations are not affected by the higher
derivative terms. For fixed the set of black hole solutions terminates
at an extremal black hole with a regular horizon, where the Hawking temperature
vanishes and the angular momenta attain their extremal values. The domain of
existence of regular black hole solutions is studied. The near horizon geometry
of the extremal solutions is determined by employing the entropy function
formalism.Comment: 25 pages, 7 figure
Perturbations of Gauss-Bonnet Black Strings in Codimension-2 Braneworlds
We derive the Lichnerowicz equation in the presence of the Gauss-Bonnet term.
Using the modified Lichnerowicz equation we study the metric perturbations of
Gauss-Bonnet black strings in Codimension-2 Braneworlds.Comment: 26 pages, no figures, clarifying comments and one reference added, to
be published in JHE
Lovelock gravity from entropic force
In this paper, we first generalize the formulation of entropic gravity to
(n+1)-dimensional spacetime. Then, we propose an entropic origin for
Gauss-Bonnet gravity and more general Lovelock gravity in arbitrary dimensions.
As a result, we are able to derive Newton's law of gravitation as well as the
corresponding Friedmann equations in these gravity theories. This procedure
naturally leads to a derivation of the higher dimensional gravitational
coupling constant of Friedmann/Einstein equation which is in complete agreement
with the results obtained by comparing the weak field limit of Einstein
equation with Poisson equation in higher dimensions. Our study shows that the
approach presented here is powerful enough to derive the gravitational field
equations in any gravity theory. PACS: 04.20.Cv, 04.50.-h, 04.70.Dy.Comment: 10 pages, new versio
Evanescent light-matter Interactions in Atomic Cladding Wave Guides
Alkali vapors, and in particular rubidium, are being used extensively in
several important fields of research such as slow and stored light non-linear
optics3 and quantum computation. Additionally, the technology of alkali vapors
plays a major role in realizing myriad industrial applications including for
example atomic clocks magentometers8 and optical frequency stabilization.
Lately, there is a growing effort towards miniaturizing traditional
centimeter-size alkali vapor cells. Owing to the significant reduction in
device dimensions, light matter interactions are greatly enhanced, enabling new
functionalities due to the low power threshold needed for non-linear
interactions. Here, taking advantage of the mature Complimentary
Metal-Oxide-Semiconductor (CMOS) compatible platform of silicon photonics, we
construct an efficient and flexible platform for tailored light vapor
interactions on a chip. Specifically, we demonstrate light matter interactions
in an atomic cladding wave guide (ACWG), consisting of CMOS compatible silicon
nitride nano wave-guide core with a Rubidium (Rb) vapor cladding. We observe
the highly efficient interaction of the electromagnetic guided mode with the
thermal Rb cladding. The nature of such interactions is explained by a model
which predicts the transmission spectrum of the system taking into account
Doppler and transit time broadening. We show, that due to the high confinement
of the optical mode (with a mode area of 0.3{\lambda}2), the Rb absorption
saturates at powers in the nW regime.Comment: 10 Pages 4 Figures. 1 Supplementar
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