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Byline: Nandini. Lulla, M. Loganathan, V. Balan, S. Swathi Purpose: Dry eye is a multifactorial disease of the ocular surface. It showed an increased incidence during the pandemic situation, which [...]

Within the frame of reliability models, the geometry of constant level sets of the reliability function of a complex circuit – regarded as hypersurfaces, reveals properties which provide useful information on the relation between the reliability of the circuit and its components. A special role plays the study of intersections of these hypersurfaces with 2-dimensional plane slices, which provide a foliation by pencils of algebraic curves. The present study classifies these pencils and consequently, it allows: (i) to evaluate the possible bounds of the bivariate slice-reliability in terms of the circuit components; (ii) to compensate the impact of a slice-component malfunction on the slice-reliability, by tuning the appropriate pairing slice-component; (iii) to flag out the cases when the slice-reliability is linear (mono- or bi-variate) in the slice-components, or constant along the whole slice; (iv) in the quadratic case, to make use the convex/concave mutual dependence of slice-components along the curves of constant-slice reliability, in order to maintain or increase the circuit reliability.

Coronary artery stents used for the treatment of patients with coronary artery disease develop the practice of interventional cardiology after they were first introduced in the mid-1980s. Since then, with dozens of companies involved in the development of new and innovative anti-restenotic drugs, polymeric coatings and stent platforms has made significant progress in this area. Today, the challenge is the conception of the “ideal” coronary stent designed to respond to the patient health difficulty. In this context, the literature in the field is quite dynamic and successful. The aim of this article is to provide a systematic review on the interdisciplinary field literature of the evolution of these medical devices by describing the current status, importance and different types of stents used in clinical practice. After the presentation of cardiovascular problems associated to stenting therapy, the authors describe the bare metal stents, the generations of drug eluting stents and the future in progress directions regarding: the stents based on biodegradable/bioresorbable polymers, polymer-free metal platforms, fully biodegradable scaffolds, as well as drug delivery mediated by stent-targeted magnetic nanoparticles.

The liver organ allocation policy of the United Network for Organ Sharing (UNOS) is based on the model for end-stage liver disease (MELD). The policy provides additional priority for candidates with hepatocellular carcinoma (HCC) who are awaiting deceased donor liver transplantation (DDLT). However, this priority was reduced on February 27, 2003 to a MELD of 20 for stage T1 and of 24 for stage T2 HCC. The aim of this study was to determine the impact of reduced priority on HCC candidate survival while on the waiting list. The UNOS database was reviewed for all HCC candidates listed after February 27, 2002, The HCC candidates were grouped into two time periods: MELD 1 (listed between February 27, 2002, and February 26, 2003) and MELD 2 (listed between February 27, 2003 and February 26, 2004). For the two time periods, the national DDLT incidence rates for HCC patients were 1.44 versus 1.53 DDLT per person-year (p = NS) and the waiting times were similar for the two periods (138.0 ± 196.8 vs. 129.0 ± 133.8 days; p = NS). Furthermore, the 3-, 6- and 12-month candidate, patient survival and dropout rates were also similar nationally. Regional differences in rates of DDLT for HCC were observed during both MELD periods. Consequently, the reduced MELD score for stage T1 and T2 HCC candidates awaiting DDLT has not had an impact nationally either on their survival on the waiting list or on their ability to obtain a liver transplant within a reasonable time frame. However, regional variations point to the need for reform in how organs are allocated for HCC at the regional level.

Rapid quenching in a protective atmosphere of carbon dioxide at an optimal combination of parameters improves substantially the quality of ribbons of alloy Fe-6.5 Si in comparison with ribbons obtained in air or with the use of helium or argon. Better quality of the ribbons improves substantially the level of their magnetic properties.

Integral representations of the components of the displacement vector and the stress tensor and the corresponding system of boundary integral equations are derived for a piecewise-homogeneous body. A numerical scheme is developed that allows for the specific behavior of the stress fields in the neighborhood of the corner points of the inclusions. As an example, we consider the thermally stressed state of an elastic half-plane with inclusions of various shapes.

During bile formation by the liver, large volumes of water are transported across two epithelial barriers consisting of hepatocytes and cholangiocytes (i.e. intrahepatic bile duct epithelial cells). We recently reported that a water channel, aquaporin-channel-forming integral protein of 28 kDa, is present in cholangiocytes and suggested that it plays a major role in water transport by these cells. Since the mechanisms of water transport across hepatocytes remain obscure, we performed physiological, molecular, and biochemical studies on hepatocytes to determine if they also contain water channels. Water permeability was studied by exposing isolated rat hepatocytes to buffers of different osmolarity and measuring cell volume by quantitative phase contrast, fluorescence and laser scanning confocal microscopy. Using this method, hepatocytes exposed to hypotonic buffers at 23 degrees C increased their cell volume in a time and osmolarity-dependent manner with an osmotic water permeability coefficient of 66.4 x 10(-4) cm/s. In studies done at 10 degrees C, the osmotic water permeability coefficient decreased by 55% (p < 0.001, at 23 degrees C; t test). The derived activation energy from these studies was 12.8 kcal/mol. After incubation of hepatocytes with amphotericin B at 10 degrees C, the osmotic water permeability coefficient increased by 198% (p < 0.001) and the activation energy value decreased to 3.6 kcal/mol, consistent with the insertion of artificial water channels into the hepatocyte plasma membrane. Reverse transcriptase polymerase chain reaction with hepatocyte RNA as template did not produce cDNAs for three of the known water channels. Both the cholesterol content and the cholesterol/phospholipid ratio of hepatocyte plasma membranes were significantly (p < 0.005) less than those of cholangiocytes; membrane fluidity of hepatocytes estimated by measuring steady-state anisotropy was higher than that of cholangiocytes. Our data suggests that the osmotic flow of water across hepatocyte membranes occurs mainly by diffusion via the lipid bilayer (not by permeation through water channels as in cholangiocytes).

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As is seen from Fig. 5, elevated stress zones are formed for small distances d<0.2a between the inclusions. In practice there is no mutual influence between the inclusions for distances d>2.5a since the distribution of the stress along the line x1=0 for d=5a is the same as for the case of a half-plane without inclusions.