466 research outputs found
Recommended from our members
The use of fractally-designed waveforms in electroforming
Pulsed electrodeposition offers the potential for superior control of deposit properties because of the additional control variables available. However, optimization of pulsed deposition processes is a challenge because of the complexity. E.g., the tendency of electroforms to acquire irregularities such as dendritic growths or other morphological instabilities, creates the need for methods to control these undesirable phenomena. One such method is periodic reverse pulses. Optimization of periodic reverse processes is not simple and can lead to local solutions that do not optimize all properties simultaneously. One method for global optimization that might, for example, control surface irregularities on several size scales, uses a periodic reverse design based on fractal time series. This incorporates deplating pulses of several lengths within one self- similar waveform. The properties of fractals permit control of highly complex designs with a small number of input variables. The creation of such waveforms, their properties, and their use in a lead- plating process are described. Speculation on the potential for further application of this method is offered. 26 figs, 11 refs
Characterisation of Crandell-Rees Feline Kidney (CRFK) cells as mesenchymal in phenotype
The Crandell-Rees Feline Kidney Cell (CRFK) is an immortalised cell line derived from the feline kidney that is utilised for the growth of certain vaccinal viruses. Confusion exists as to whether CRFK are epithelial or mesenchymal in phenotype. The aim of this study was to characterise CRFK cells via immunofluorescence, enzyme cytochemistry, western blotting, RT-qPCR for S100A4 and comparison to primary feline proximal tubular epithelial cells (FPTEC) and feline cortical fibroblasts (FCF). CRFK cells were of fusiform morphology and appeared similar to FCF. CRFK expressed the mesenchymal intermediate filament (IF) protein vimentin together with two cell adhesion molecules associated with feline fibroblasts (CD29 and CD44), and lacked expression of the epithelial IF cytokeratin, myogenic IF desmin and endothelial marker von Willebrand factor (vWF). In addition, CRFK did not demonstrate brush border enzyme activity typical of FPTEC. S100A4 gene expression, implicated in both neoplastic transformation and epithelial to mesenchymal transition, was highly upregulated in CRFK in comparison to the primary feline renal cells. CRFK appear phenotypically similar to fibroblasts, rather than tubular epithelial cells, and may have undergone neoplastic transformation or epithelial-to-mesenchymal transition after extensive passaging. This finding may have potential implications for future research utilising this cell line
Urinary active transforming growth factor Ăź in feline chronic kidney disease
The cytokine transforming growth factor beta 1 (TGF-β1) has been widely implicated in the development and progression of renal fibrosis in chronic kidney disease (CKD) in humans and in experimental models. The aims of this study were to assess the association between urinary active TGF-β1 and (a) development of CKD in a cross-sectional study, (b) deterioration of renal function over 1 year in a longitudinal study, and (c) renal histopathological parameters in cats. A human active TGF-β1 ELISA was validated for use in feline urine.
Cross-sectional analysis revealed no significant difference in urinary active TGF-β1:creatinine ratio (aTGF-β1:UCr) between groups with differing renal function. Longitudinally, non-azotaemic cats that developed CKD demonstrated a significant (P = 0.028) increase in aTGF-β1:UCr approximately 6 months before the development of azotaemia, which remained elevated (P = 0.046) at diagnosis (approximately 12 months prior, 8.4 pg/mg; approximately 6 months prior, 22.2 pg/mg; at CKD diagnosis, 24.6 pg/mg). In the histopathology study, aTGF-β1:UCr was significantly higher in cats with moderate (P = 0.02) and diffuse (P = 0.005) renal fibrosis than in cats without fibrosis. Cats with moderate renal inflammation had significantly higher urinary active aTGF-β1 concentrations than cats with mild (P = 0.035) or no inflammatory change (P = 0.004). The parameter aTGF-β1:UCr was independently associated with Log urine protein:creatinine ratio in a multivariable analysis of clinicopathological parameters and interstitial fibrosis score in a multivariable analysis of histopathological features. These results suggest that urinary aTGF-β1 reflects the severity of renal pathology. Increases in urinary aTGF-β1 followed longitudinally in individual cats may indicate the development of CKD
4f spin density in the reentrant ferromagnet SmMn2Ge2
The spin contribution to the magnetic moment in SmMn2Ge2 has been measured by
magnetic Compton scattering in both the low and high temperature ferromagnetic
phases. At low temperature, the Sm site is shown to possess a large 4f spin
moment of 3.4 +/- 0.1 Bohr magnetons, aligned antiparallel to the total
magnetic moment. At high temperature, the data show conclusively that ordered
magnetic moments are present on the samarium site.Comment: 5 pages, 2 figures, transferred from PRL to PRB (Rapid Comm.
Special Geometry of Euclidean Supersymmetry I: Vector Multiplets
We construct the general action for Abelian vector multiplets in rigid
4-dimensional Euclidean (instead of Minkowskian) N=2 supersymmetry, i.e., over
space-times with a positive definite instead of a Lorentzian metric. The target
manifolds for the scalar fields turn out to be para-complex manifolds endowed
with a particular kind of special geometry, which we call affine special
para-Kahler geometry. We give a precise definition and develop the mathematical
theory of such manifolds. The relation to the affine special Kahler manifolds
appearing in Minkowskian N=2 supersymmetry is discussed. Starting from the
general 5-dimensional vector multiplet action we consider dimensional reduction
over time and space in parallel, providing a dictionary between the resulting
Euclidean and Minkowskian theories. Then we reanalyze supersymmetry in four
dimensions and find that any (para-)holomorphic prepotential defines a
supersymmetric Lagrangian, provided that we add a specific four-fermion term,
which cannot be obtained by dimensional reduction. We show that the Euclidean
action and supersymmetry transformations, when written in terms of
para-holomorphic coordinates, take exactly the same form as their Minkowskian
counterparts. The appearance of a para-complex and complex structure in the
Euclidean and Minkowskian theory, respectively, is traced back to properties of
the underlying R-symmetry groups. Finally, we indicate how our work will be
extended to other types of multiplets and to supergravity in the future and
explain the relevance of this project for the study of instantons, solitons and
cosmological solutions in supergravity and M-theory.Comment: 74 page
Transnational partisanship: idea and practice
That parties might successfully organize transnationally is an idea often met with scepticism. This article argues that while certain favourable conditions are indeed absent in the transnational domain, this implies not that partisanship is impossible but that it is likely to be marked by certain traits. Specifically, it will tend to be episodic, structured as a low-density network and delocalized in its ideational content. These tendencies affect the normative expectations one can attach to it. Transnational partisanship should be valued as a transitional phenomenon, e.g. as a pathway to transnational democracy, more than as a desirable thing in itself
A measurement of the tau mass and the first CPT test with tau leptons
We measure the mass of the tau lepton to be 1775.1+-1.6(stat)+-1.0(syst.) MeV
using tau pairs from Z0 decays. To test CPT invariance we compare the masses of
the positively and negatively charged tau leptons. The relative mass difference
is found to be smaller than 3.0 10^-3 at the 90% confidence level.Comment: 10 pages, 4 figures, Submitted to Phys. Letts.
Measurement of the B0 Lifetime and Oscillation Frequency using B0->D*+l-v decays
The lifetime and oscillation frequency of the B0 meson has been measured
using B0->D*+l-v decays recorded on the Z0 peak with the OPAL detector at LEP.
The D*+ -> D0pi+ decays were reconstructed using an inclusive technique and the
production flavour of the B0 mesons was determined using a combination of tags
from the rest of the event. The results t_B0 = 1.541 +- 0.028 +- 0.023 ps, Dm_d
= 0.497 +- 0.024 +- 0.025 ps-1 were obtained, where in each case the first
error is statistical and the second systematic.Comment: 17 pages, 4 figures, submitted to Phys. Lett.
First Measurement of Z/gamma* Production in Compton Scattering of Quasi-real Photons
We report the first observation of Z/gamma* production in Compton scattering
of quasi-real photons. This is a subprocess of the reaction e+e- to
e+e-Z/gamma*, where one of the final state electrons is undetected.
Approximately 55 pb-1 of data collected in the year 1997 at an e+e-
centre-of-mass energy of 183 GeV with the OPAL detector at LEP have been
analysed. The Z/gamma* from Compton scattering has been detected in the
hadronic decay channel. Within well defined kinematic bounds, we measure the
product of cross-section and Z/gamma* branching ratio to hadrons to be
(0.9+-0.3+-0.1) pb for events with a hadronic mass larger than 60 GeV,
dominated by (e)eZ production. In the hadronic mass region between 5 GeV and 60
GeV, dominated by (e)egamma* production, this product is found to be
(4.1+-1.6+-0.6) pb. Our results agree with the predictions of two Monte Carlo
event generators, grc4f and PYTHIA.Comment: 18 pages, LaTeX, 5 eps figures included, submitted to Physics Letters
Search for Higgs Bosons in e+e- Collisions at 183 GeV
The data collected by the OPAL experiment at sqrts=183 GeV were used to
search for Higgs bosons which are predicted by the Standard Model and various
extensions, such as general models with two Higgs field doublets and the
Minimal Supersymmetric Standard Model (MSSM). The data correspond to an
integrated luminosity of approximately 54pb-1. None of the searches for neutral
and charged Higgs bosons have revealed an excess of events beyond the expected
background. This negative outcome, in combination with similar results from
searches at lower energies, leads to new limits for the Higgs boson masses and
other model parameters. In particular, the 95% confidence level lower limit for
the mass of the Standard Model Higgs boson is 88.3 GeV. Charged Higgs bosons
can be excluded for masses up to 59.5 GeV. In the MSSM, mh > 70.5 GeV and mA >
72.0 GeV are obtained for tan{beta}>1, no and maximal scalar top mixing and
soft SUSY-breaking masses of 1 TeV. The range 0.8 < tanb < 1.9 is excluded for
minimal scalar top mixing and m{top} < 175 GeV. More general scans of the MSSM
parameter space are also considered.Comment: 49 pages. LaTeX, including 33 eps figures, submitted to European
Physical Journal
- …