Some remarks on particle size effects on the abrasion of a range of Fe based alloys

The low-stress three body abrasion behaviour of a range of steels was investigated. The tests were carried out in a rubber wheel tester (according to ASTM G65-94, reapproved in 2000) at room temperature. The abrasive particles used were angular alumina particles of four different sizes. The results showed that, in general, the smaller particles (50 8m and 125 8m average size) caused more damage. With these particles, observations of surface morphology indicarted a more intense cutting and ploughing action, leading to more damage, whereas bigger particles i.e. larger 250 8m and 560 8m particles produced less damage, and their action involved more plastic deformation type wear. The 304 SS had a lower abrasion resistance than the 310 SS. For the austentic and ferritic steels the subsurface deformation was larger for impact with the coarser particles. Variations in substrate hardness had no effect on the abrasive behaviour observed. On the whole, the hardest steel (mild steel in martensitic condition) showed the higher extent of damage, irrespective of particle size

Gribov Copies in the Maximally Abelian Gauge and Confinement

We fix $SU(2)$ lattice gauge fields to the Maximally Abelian gauge in both three and four dimensions. We extract the corresponding $U(1)$ fields and monopole current densities and calculate separately the confining string tensions arising from these $U(1)$ fields and monopole `condensates'. We generate multiple Gribov copies and study how the $U(1)$ fields and monopole distributions vary between these different copies. As expected, we find substantial variations in the number of monopoles, their locations and in the values of the $U(1)$ field strengths. The string tensions extracted from `extreme' Gribov copies also differ but this difference appears to be no more than about 20\%. We also directly compare the fields of different Gribov copies. We find that on the distance scales relevant to confinement the $U(1)$ and monopole fluxes that disorder Wilson loops are highly correlated between these different Gribov copies. All this suggests that while there is indeed a Gribov copy problem the resulting ambiguity is, in this gauge and for the study of confinement, of limited importance.Comment: 31 pages LaTeX plus 5 PostScript figures. Uses epsf.sty. Self-unpacking, uuencoded tar-compressed fil

String Tension from Monopoles in SU(2) Lattice Gauge Theory

The axis for Figure 2 was wrong. It has been fixed and the postscript file replaced (The file was called comp.ps).Comment: (22 pages latex (revtex); 2 figures appended as postscript files - search for mono.ps and comp.ps. Figures mailed on request--send a note to [email protected]) Preprint ILL-(TH)-94-#1

Large Loops of Magnetic Current and Confinement in Four Dimensional U(1)U(1) Lattice Gauge Theory

We calculate the heavy quark potential from the magnetic current due to monopoles in four dimensional $U(1)$ lattice gauge theory. The magnetic current is found from link angle configurations using the DeGrand-Toussaint identification method. The link angle configurations are generated in a cosine action simulation on a $24^4$ lattice. The magnetic current is resolved into large loops which wrap around the lattice and simple loops which do not. Wrapping loops are found only in the confined phase. It is shown that the long range part of the heavy quark potential, in particular the string tension, can be calculated solely from the large, wrapping loops of magnetic current.Comment: 15 pages (Latex file plus 3 postscript files appended), Univeristy of Illinois Preprint ILL-(TH)-93-\#1

Monopole clusters, Z(2) vortices and confinement in SU(2)

We extend our previous study of magnetic monopole currents in the maximally Abelian gauge [hep-lat/9712003] to larger lattices at small lattice spacings (20^4 at beta = 2.5 and 32^4 at beta = 2.5115). We confirm that at these weak couplings there continues to be one monopole cluster that is very much longer than the rest and that the string tension, K, is entirely due to it. The remaining clusters are compact objects whose population as a function of radius follows a power law that deviates from the scale invariant form, but much too weakly to suggest a link with the analytically calculable size distribution of small instantons. We also search for traces of Z(2) vortices in the Abelian projected fields; either as closed loops of `magnetic' flux or through appropriate correlations amongst the monopoles. We find, by direct calculation, that there is no confining condensate of such flux loops. We also find, through the calculation of doubly charged Wilson loops within the monopole fields, that there is no suppression of the q=2 effective string tension out to at distances of at least r ~ 1.6/sqrt{K}, suggesting that if there are any vortices they are not encoded in the monopole fields.Comment: 26 pages of LaTeX and PostScript figure

Vaccinia virus protein A46R targets multiple Toll-like-interleukin-1 receptor adaptors and contributes to virulence

Viral immune evasion strategies target key aspects of the host antiviral response. Recently, it has been recognized that Toll-like receptors (TLRs) have a role in innate defense against viruses. Here, we define the function of the vaccinia virus (VV) protein A46R and show it inhibits intracellular signalling by a range of TLRs. TLR signalling is triggered by homotypic interactions between the Toll-like-interleukin-1 resistance (TIR) domains of the receptors and adaptor molecules. A46R contains a TIR domain and is the only viral TIR domain-containing protein identified to date. We demonstrate that A46R targets the host TIR adaptors myeloid differentiation factor 88 (MyD88), MyD88 adaptor-like, TIR domain-containing adaptor inducing IFN-beta (TRIF), and the TRIF-related adaptor molecule and thereby interferes with downstream activation of mitogen-activated protein kinases and nuclear factor kappaB. TRIF mediates activation of interferon (IFN) regulatory factor 3 (IRF3) and induction of IFN-beta by TLR3 and TLR4 and suppresses VV replication in macrophages. Here, A46R disrupted TRIF-induced IRF3 activation and induction of the TRIF-dependent gene regulated on activation, normal T cell expressed and secreted. Furthermore, we show that A46R is functionally distinct from another described VV TLR inhibitor, A52R. Importantly, VV lacking the A46R gene was attenuated in a murine intranasal model, demonstrating the importance of A46R for VV virulence

The Coulomb law in the pure gauge U(1) theory on a lattice

We study the heavy charge potential in the Coulomb phase of pure gauge compact U(1) theory on the lattice. We calculate the static potential $V_W(T,{\vec R})$ from Wilson loops on a $16^3 \times 32$ lattice and compare with the predictions of lattice perturbation theory. We investigate finite size effects and, in particular, the importance of non-Coulomb contributions to the potential. We also comment on the existence of a maximal coupling in the Coulomb phase of pure gauge U(1) theory.Comment: 14 pages. LaTeX file and 3 postscript figure

Impact of dialysis modality on survival of new ESRD patients with congestive heart failure in the United States

Impact of dialysis modality on survival of new ESRD patients with congestive heart failure in the United States.BackgroundIt is hypothesized, but not proven, that peritoneal dialysis might be the optimal treatment for end-stage renal disease (ESRD) patients with established congestive heart failure (CHF) through better volume regulation compared with hemodialysis.MethodsNational incidence data on 107,922 new ESRD patients from the Center for Medicare and Medicaid Services (CMS) Medical Evidence Form were used to test the hypothesis that peritoneal dialysis was superior to hemodialysis in prolonging survival of patients with CHF. Nonproportional Cox regression models evaluated the relative hazard of death for patients with and without CHF by dialysis modality using primarily the intent-to-treat but also the as-treated approach. Diabetics and nondiabetics were analyzed separately.ResultsThe overall prevalence of CHF was 33% at ESRD initiation. There were 27,149 deaths (25.2%), 5423 transplants (5%), and 3753 (3.5%) patients lost to follow-up over 2years. Adjusted mortality risks were significantly higher for patients with CHF treated with peritoneal dialysis than hemodialysis [diabetics, relative risk (RR) = 1.30, 95% confidence interval (CI) 1.20 to 1.41; nondiabetics, RR = 1.24, 95% CI 1.14 to 1.35]. Among patients without CHF, adjusted mortality risk were higher only for diabetic patients treated with peritoneal dialysis compared with hemodialysis (RR = 1.11, 95% CI 1.02 to 1.21) while nondiabetics had similar survival on peritoneal dialysis or hemodialysis (RR = 0.97, 95% CI 0.91 to 1.04).ConclusionNew ESRD patients with a clinical history of CHF experienced poorer survival when treated with peritoneal dialysis compared with hemodialysis. These data suggest that peritoneal dialysis may not be the optimal choice for new ESRD patients with CHF perhaps through impaired volume regulation and worsening cardiomyopathy

Monopole clusters in Abelian projected gauge theories

We show that the monopole currents which one obtains in the maximally Abelian gauge of SU(2) fall into two quite distinct classes (when the volume is large enough). In each field configuration there is precisely one cluster that permeates the whole lattice volume. It has a current density and a magnetic screening mass that scale and it produces the whole of the string tension. The remaining clusters have a number density that follows an approximate power law proportional to the inverse cube of l where l is the length of the monopole world line in lattice units. These clusters are localised in space-time with radii which vary as the square root of l. In terms of the radius r these `lumps' have a scale-invariant distribution proportional to (dr/r . 1/{r^4}). Moreover they appear not to contribute at all to the string tension. The fact that they are scale-invariant at small distances would seem to rule out an instanton origin.Comment: LaTeX, 31 pages, 11 PostScript figures. Typo in Table 2 correcte