1,563 research outputs found
Comparison of fluorescence-based techniques for the quantification of particle-induced hydroxyl radicals
<p>Abstract</p> <p>Background</p> <p>Reactive oxygen species including hydroxyl radicals can cause oxidative stress and mutations. Inhaled particulate matter can trigger formation of hydroxyl radicals, which have been implicated as one of the causes of particulate-induced lung disease. The extreme reactivity of hydroxyl radicals presents challenges to their detection and quantification. Here, three fluorescein derivatives [aminophenyl fluorescamine (APF), amplex ultrared, and dichlorofluorescein (DCFH)] and two radical species, proxyl fluorescamine and tempo-9-ac have been compared for their usefulness to measure hydroxyl radicals generated in two different systems: a solution containing ferrous iron and a suspension of pyrite particles.</p> <p>Results</p> <p>APF, amplex ultrared, and DCFH react similarly to the presence of hydroxyl radicals. Proxyl fluorescamine and tempo-9-ac do not react with hydroxyl radicals directly, which reduces their sensitivity. Since both DCFH and amplex ultrared will react with reactive oxygen species other than hydroxyl radicals and another highly reactive species, peroxynitite, they lack specificity.</p> <p>Conclusion</p> <p>The most useful probe evaluated here for hydroxyl radicals formed from cell-free particle suspensions is APF due to its sensitivity and selectivity.</p
High performance compression of science data
Two papers make up the body of this report. One presents a single-pass adaptive vector quantization algorithm that learns a codebook of variable size and shape entries; the authors present experiments on a set of test images showing that with no training or prior knowledge of the data, for a given fidelity, the compression achieved typically equals or exceeds that of the JPEG standard. The second paper addresses motion compensation, one of the most effective techniques used in the interframe data compression. A parallel block-matching algorithm for estimating interframe displacement of blocks with minimum error is presented. The algorithm is designed for a simple parallel architecture to process video in real time
Multidisciplinary team meetings in palliative care: an ethnographic study
OBJECTIVES: Multidisciplinary team meetings are a regular feature in the provision of palliative care, involving a range of professionals. Yet, their purpose and best format are not necessarily well understood or documented. This article describes how hospital and community-based palliative care multidisciplinary team meetings operate to elucidate some of their main values and offer an opportunity to share examples of good practice. METHODS: Ethnographic observations of over 70 multidisciplinary team meetings between May 2018 and January 2020 in hospital and community palliative care settings in intercity London. These observations were part of a larger study examining palliative care processes. Fieldnotes were thematically analysed. RESULTS: This article analyses how the meetings operated in terms of their setup, participants and general order of business. Meetings provided a space where patients, families and professionals could be cared for through regular discussions of service provision. CONCLUSIONS: Meetings served a variety of functions. Alongside discussing the more technical, clinical and practical aspects that are formally recognised aspects of the meetings, an additional core value was enabling affectual aspects of dealing with people who are dying to be acknowledged and processed collectively. Insight into how the meetings are structured and operate offer input for future practice
Algebras in Higher Dimensional Statistical Mechanics - the Exceptional Partition (MEAN Field) Algebras
We determine the structure of the partition algebra (a generalized
Temperley-Lieb algebra) for specific values of Q \in \C, focusing on the
quotient which gives rise to the partition function of site -state Potts
models (in the continuous formulation) in arbitrarily high lattice
dimensions (the mean field case). The algebra is non-semi-simple iff is a
non-negative integer less than . We determine the dimension of the key
irreducible representation in every specialization.Comment: 4 page
Ariel - Volume 5 Number 1
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Bound States in one and two Spatial Dimensions
In this paper we study the number of bound states for potentials in one and
two spatial dimensions. We first show that in addition to the well-known fact
that an arbitrarily weak attractive potential has a bound state, it is easy to
construct examples where weak potentials have an infinite number of bound
states. These examples have potentials which decrease at infinity faster than
expected. Using somewhat stronger conditions, we derive explicit bounds on the
number of bound states in one dimension, using known results for the
three-dimensional zero angular momentum. A change of variables which allows us
to go from the one-dimensional case to that of two dimensions results in a
bound for the zero angular momentum case. Finally, we obtain a bound on the
total number of bound states in two dimensions, first for the radial case and
then, under stronger conditions, for the non-central case.Comment: Latex, 27pp no figure
Zassenhaus conjecture for central extensions of S5
We confirm a conjecture of Zassenhaus about rational conjugacy of torsion units in
integral group rings for a covering group of the symmetric group S5 and for the general linear
group GLð2; 5Þ. The first result, together with others from the literature, settles the conjugacy
question for units of prime-power order in the integral group ring of a finite Frobenius group
Heat Conduction and Magnetic Phase Behavior in Electron-Doped Ca_{1-x} La_x MnO_3(0 <= x <= 0.2)
Measurements of thermal conductivity (kappa) vs temperature are reported for
a series of Ca_{1-x} La_x MnO_3(0 <= x <= 0.2) specimens. For the undoped
(x=0), G-type antiferromagnetic compound a large enhancement of kappa below the
Neel temperature (T_N ~ 125 K) indicates a strong coupling of heat-carrying
phonons to the spin system. This enhancement exhibits a nonmonotonic behavior
with increasing x and correlates remarkably well with the small ferromagnetic
component of the magnetization reported previously [Neumeier and Cohn, Phys.
Rev. B 61 14319 (2000).] Magnetoelastic polaron formation appears to underly
the behavior of kappa and the magnetization at x <= 0.02.Comment: submitted to PRB; 4 pp., 4 Fig.'s, RevTex
Role of pyrite in formation of hydroxyl radicals in coal: possible implications for human health
BACKGROUND: The harmful effects from inhalation of coal dust are well-documented. The prevalence of lung disease varies by mining region and may, in part, be related to regional differences in the bioavailable iron content of the coal. Pyrite (FeS(2)), a common inorganic component in coal, has been shown to spontaneously form reactive oxygen species (ROS) (i.e., hydrogen peroxide and hydroxyl radicals) and degrade nucleic acids. This raises the question regarding the potential for similar reactivity from coal that contains pyrite. Experiments were performed to specifically evaluate the role of pyrite in coal dust reactivity. Coal samples containing various amounts of FeS(2 )were compared for differences in their generation of ROS and degradation of RNA. RESULTS: Coals that contain iron also show the presence of FeS(2), generate ROS and degrade RNA. Coal samples that do not contain pyrite do not produce ROS nor degrade RNA. The concentration of generated ROS and degradation rate of RNA both increase with greater FeS(2 )content in the coals. CONCLUSION: The prevalence of coal workers' pneumoconiosis can be correlated to the amount of FeS(2 )in the coals. Considering the harmful effects of generation of ROS by inhaled particles, the results presented here show a possible mechanism whereby coal samples may contribute to CWP. This suggests that the toxicity of coal may be explained, in part, by the presence of FeS(2)
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