The use of modern techniques of biliary tract monitoring in percutaneous drainage

The aim of this work is to assess the usefulness of current imaging techniques of biliary tracts in percutaneous transhepatic biliary drainage (PTBD). In the period from January 1996 to March 2003 44 cases of PTBD were carried out under ultrasonographic and X-ray control in 34 patients who could not have a bypass or endoscopic prothesis of the bile duct. The effectiveness of the method was evaluated in relation to the extent of the intra-hepatic bile ducts, the usefulness of simultaneous monitoring (ultrasonography and X-ray) and the possibility of preoperative contrasting of the bile ducts. Correct drainage of bile ducts was achieved in 43 PTBD. In 6 cases branches of the portal vein were pierced during drainage, but thanks to X-ray visualisation this was detected and the bile ducts were then drained correctly. During 4 PTBD the grooved probe slipped from bile ducts while the catheter was being introduced and a repeated prick was necessary. Total cholestasis caused by a tumour does not always bring about extension of bile ducts. However, simultaneous ultrasonographic and X-ray imaging of the bile ducts enables PTBD to be performed even in patients with a slight extension of the duct

Intraoperative monitoring of the biliary tracts as a means of preventing choledocholithiasis oversight

The aim of the work is to assess the performance and effectiveness of intraoperative cholangiography or choledochoscopy in the prevention of choledocholithiasis oversight. The effectiveness of choledochoscopy was assessed in 50 patients during the years 2001–2002. Since 2000 intraoperative cholangiography has been performed on all patients after classic cholecystostomy in the absence of indications to choledochotomy. The effectiveness of intraoperative cholangiography was assessed in 50 patients in 2001. Both groups underwent ultrasonographic control and tests of biochemical parameters a year after surgery. The advisability of performing intraoperative cholangiography or choledochoscopy and their high degree of effectiveness in the prevention of choledocholithiasis oversight was confirmed

RANDOM SIMPLICIAL COMPLEXES, DUALITY AND THE CRITICAL DIMENSION

In this paper we discuss two general models of random simplicial complexes which we call the lower and the upper models. We show that these models are dual to each other with respect to combinatorial Alexander duality. The behaviour of the Betti numbers in the lower model is characterised by the notion of critical dimension, which was introduced by A. Costa and M. Farber: random simplicial complexes in the lower model are homologically approximated by a wedge of spheres of dimension equal the critical dimension. In this paper we study the Betti numbers in the upper model and introduce new notions of critical dimension and spread. We prove that (under certain conditions) an upper random simplicial complex is homologically approximated by a wedge of spheres of the critical dimension.Comment: 31 pages Fixed an error in the proofs approximating the number of simplices in the upper mode

The combinatorics of the Baer-Specker group

Denote the integers by Z and the positive integers by N. The groups Z^k (k a natural number) are discrete, and the classification up to isomorphism of their (topological) subgroups is trivial. But already for the countably infinite power Z^N of Z, the situation is different. Here the product topology is nontrivial, and the subgroups of Z^N make a rich source of examples of non-isomorphic topological groups. Z^N is the Baer-Specker group. We study subgroups of the Baer-Specker group which possess group theoretic properties analogous to properties introduced by Menger (1924), Hurewicz (1925), Rothberger (1938), and Scheepers (1996). The studied properties were introduced independently by Ko\v{c}inac and Okunev. We obtain purely combinatorial characterizations of these properties, and combine them with other techniques to solve several questions of Babinkostova, Ko\v{c}inac, and Scheepers.Comment: To appear in IJ

Long-Term Degradation Mechanisms in Application-Implemented Radical Thin Films

Blatter radical derivatives are very attractive due to their potential applications, ranging from batteries to quantum technologies. In this work, we focus on the latest insights regarding the fundamental mechanisms of radical thin film (long-term) degradation, by comparing two Blatter radical derivatives. We find that the interaction with different contaminants (such as atomic H, Ar, N, and O and molecular H2, N2, O2, H2O, and NH2) affects the chemical and magnetic properties of the thin films upon air exposure. Also, the radical-specific site, where the contaminant interaction takes place, plays a role. Atomic H and NH2 are detrimental to the magnetic properties of Blatter radicals, while the presence of molecular water influences more specifically the magnetic properties of the diradical thin films, and it is believed to be the major cause of the shorter diradical thin film lifetime in air

Magneto-transport and magnetic susceptibility of SmFeAsO1-xFx (x = 0.0 and 0.20)

Bulk polycrystalline samples, SmFeAsO and the iso-structural superconducting SmFeAsO0.80F0.20 are explored through resistivity with temperature under magnetic field {\rho}(T, H), AC and DC magnetization (M-T), and Specific heat (Cp) measurements. The Resistivity measurement shows superconductivity for x = 0.20 sample with Tc(onset) ~ 51.7K. The upper critical field, [Hc2(0)] is estimated ~3770kOe by Ginzburg-Landau (GL) theory. Broadening of superconducting transition in magneto transport is studied through thermally activated flux flow in applied field up to 130 kOe. The flux flow activation energy (U/kB) is estimated ~1215K for 1kOe field. Magnetic measurements exhibited bulk superconductivity with lower critical field (Hc1) of ~1.2kOe at 2K. In normal state, the paramagnetic nature of compound confirms no trace of magnetic impurity which orders ferromagnetically. AC susceptibility measurements have been carried out for SmFeAsO0.80F0.20 sample at various amplitude and frequencies of applied AC drive field. The inter-granular critical current density (Jc) is estimated. Specific heat [Cp(T)] measurement showed an anomaly at around 140K due to the SDW ordering of Fe, followed by another peak at 5K corresponding to the antiferromagnetic (AFM) ordering of Sm+3 ions in SmFeAsO compound. Interestingly the change in entropy (marked by the Cp transition height) at 5K for Sm+3 AFM ordering is heavily reduced in case of superconducting SmFeAsO0.80F0.20 sample.Comment: 18 pages text + Figs: comments/suggestions welcome ([email protected]

Thermomagnetic history effects in SmMn2_2Ge2_2

The intermetallic compound SmMn$_2$Ge$_2$, displaying multiple magnetic phase transitions, is being investigated in detail for its magnetization behavior near the 145 K first order ferromagnetic to antiferromagnetic transition occuring on cooling, in particular for thermomagnetic history effects in the magnetization data. The most unusual finding is that the thermomagnetic irreversibility, [= M$^{FCW}$(T)-M$^{ZFC}$(T)] at 135 K is higher in intermediate magnetic field strengths. By studying the response of the sample (i.e., thermomagnetic irreversibility and thermal hysteresis) to different histories of application of magnetic field and temperature, we demonstrate how the supercooling and superheating of the metastable magnetic phases across the first order transition at 145 K contribute to overall thermomagnetic irreversibility.Comment: 15 pages, 5 figures, to appear in Physical Review