Integral measurements with a plutonium inert matrix fuel rod in a heterogeneous light water reactor lattice

As part of PSI's validatory efforts for neutronics calculations pertaining to inert matrix fuel (IMF) deployment in light water reactors, first-of-their-kind integral measurements have been carried out at the PROTEUS facility employing a specially fabricated Pu-Er-Zr IMF rod in a heterogeneous (boiling water reactor) test lattice. Analogous experiments have also been conducted with MOX and “dummy” IMF rods, providing the basis for a systematic comparison of experimental and calculational results.     

Dimethylsilane polyamines: cytostatic compounds with potentials as anticancer drugs

Several dimethylsilane tetramines [homologs of spermine with an Si(CH3)2 group in the central carbon chain], a carbon analog of the dimethylsilane tetramines [containing C(CH3)2 instead of Si(CH3)2] and a dimethylsilane hexamine were studied with regard to their cytotoxic activity and their ability to interact with double-stranded DNA. All polyamine analogs exerted cytostatic effects to several cell lines at micromolar concentrations. Their ability to condense DNA was comparable to and their ability to displace ethidium bromide from binding to DNA was superior to that of spermine. Their cytostatic effect was not correlated with the depletion of cellular spermidine concentrations. It is suggested that the new polyamine analogs act mainly by displacing spermidine from binding sites which are essential for the promotion of cell growth.     

Innovations in Large-Scale Supported Distance Teaching: Transformation for the Internet,Not Just Translation

This paper reports on large-scale trials of Internet-based university-level distance teaching. The use of technology, and more specifically the Internet, has been an important advance for distance education. However, simply translating material from familiar media into electronic form is rarely productive—and is certainly inadequate for supported distance education, which aims to engage the student in a “community of learning.” The value Internet technology brings to distance education lies not in direct translation from other media but in transformation of support mechanisms to exploit its potential range. The paper addresses how instruction and support functions can be served and potentially enhanced by an Internet-based structure. It considers which changes in culture help to preserve or improve teaching quality while adapting to screen-based and often asynchronous interactions. It discusses our trials of mechanisms for interactions among students and tutors; assignment marking using an electronic marking tool; electronic assignment handling; synchronous and asynchronous Internet-based problem sessions; and automatic student registration. The paper summarizes qualitative and quantitative findings of an extensive evaluation involving several hundred students over three courses and considering learning, student experience, assignment marking, problem sessions, scalability, and integration into existing administrative structures. It highlights both costs and gains of using the Internet to transform the distance learning environment for those associated with it: students, tutors, administrators, and institutions.     

Hypertrophic cardiomyopathy: spontaneous course

Hypertrophic cardiomyopathy is a relatively rare (prevalence approximately 0.2%), primary myocardial disorder with an autosomal pattern of inheritance, characterized by mostly asymmetric left ventricular hypertrophy with myocyte and myofibrillar disarray. To date, about 34 mutations of the beta-cardiac myosin heavy chain gene have been described and shown to have prognostic implications. The disease has an annual mortality rate of 3%, related to both sudden cardiac death and progressive systolic dysfunction. Not only diastolic but also progressive systolic dysfunction with cavity dilatation occurs in a minority of patients with severe hypertrophy during the long-term course. Sudden death often occurs in young, asymptomatic or mildly symptomatic patients. The degree of hypertrophy and the presence of a pressure gradient are of little prognostic significance. Nonsustained ventricular tachycardia is associated with a poor prognosis in the presence of a history of syncope.     

An Efficient Algebraic Algorithm for the Geometric Completion to Involution

 We describe an adaption of a differential algebraic completion algorithm for linear systems of partial differential equations that allows us to deduce intrinsic differential geometric information like the number of prolongations and projections needed for the completion. This new hybrid algorithm represents a much more efficient realisation of the classical Cartan–Kuranishi completion than previous purely geometric ones. A classical problem in geometric completion theory is the existence of δ-singular coordinate systems in which the algorithms do not terminate. We develop a new and a very simple criterion for δ-singularity based on a comparison of the Janet and the Pommaret division. This criterion can also be used for the direct construction of δ-regular coordinates. Received: July 28, 2000; revised version: October 16, 2001     

Tilidine does not affect human sphincter of Oddi motility--a randomized, controlled study

AIM: To investigate the effects of intravenous pentazocine and tilidine on sphincter of Oddi motility. METHODS: Twenty patients with suspected sphincter of Oddi dysfunction were enrolled in a prospective, double-blind study. Sphincter of Oddi motility was assessed by means of endoscopic manometry after injection of 0.9% saline, as well as after randomized dosing with either 30 mg pentazocine i.v. (n = 10) or 50 mg tilidine i.v. (n = 10). RESULTS: Pentazocine significantly increased the sphincter of Oddi baseline pressure from 32 +/- 21 mmHg (saline) to 41 +/- 19 mmHg (P = 0.002), whereas tilidine did not alter the sphincter baseline pressure (34 +/- 15 mmHg saline vs. 36 +/- 16 mmHg tilidine, P = 0.16). Furthermore, pentazocine increased the phasic sphincter contraction amplitude (108 +/- 16 mmHg saline vs. 121 +/- 18 mmHg pentazocine, P = 0.004), but tilidine was without any effect (125 +/- 24 mmHg saline vs. 125 +/- 21 mmHg tilidine, P = 0.93). The phasic sphincter of Oddi contraction frequency and duration were not influenced either by pentazocine or by tilidine. CONCLUSION: In contrast to 30 mg of pentazocine, 50 mg of tilidine does not affect sphincter of Oddi motility. Therefore, tilidine can be used during endoscopic manometry and for analgesia in pancreatobiliary disease.     

Troponin-T: improved diagnostic assessment of myocardial damage in childhood

Troponin-T (cTnT) as a marker of myocardial damage is well established in adults, but not yet in children. cTnT was measured in 85 children (aged 1 day-204 months, mean 46 months). Twenty-five children were non-surgical patients, with possible myocardial damage suspected on clinical grounds. The other 60 patients had cardiac surgery leading to a defined myocardial damage. In these children, troponin-T (cTnT), creatine kinase activity (CK), creatine kinase-MB activity (CK-MB), and creatine kinase-MB-Mass (CK-MB-Mass) were measured preoperatively and 3-4 times during the first 55 postoperative h. Except in four children with probable preoperative myocardial damage, all troponin-T values were in the normal range (< 0.1 microg/l). All children with intracardiac surgery showed a postoperative increase in troponin-T. Children with extracardiac surgery of the great vessels showed no postoperative increase of troponin-T. For the assessment of myocardial damage, troponin-T was more specific and more sensitive than the other markers tested, troponin-T might significantly improve the diagnostic assessment of myocardial damage in children.     

High Rate Aluminum Sputtering in Compact Disc Production

An aluminum layer of about 55 nm thickness has been awarding Compact Discs the well-known shiney appearance. The layer serves as a reflector for the pick-up laser system reading out the digital information. In state of the art single disc coaters, deposition could be done within 1.1 s by means of DC magnetron sputtering although polycarbonate, from which CDs are made, withstands only very limited temperatures. Industrial demands on productivity, reliability, low energy consumption, high target utilisation and a constant layer quality require special design considerations on sputtering sources.     

Duodenum preserving resection of the head of the pancreas: a standard procedure in chronic pancreatitis

Duodenum-preserving resection of the head of the pancreas was developed 25 years ago by Beger. This procedure is indicated in patients suffering from chronic pain in combination with inflammation of the head of the pancreas, common bile duct obstruction, pancreatic duct obstruction and/or obstruction of the retropancreatic vessels. At the Inselspital in Berne, 74 patients underwent this operation between 1993 and 1996. The median length of the operation was 380 min, with the need for transfusion in a median of 0 units (0-6). There was no postoperative mortality. Total postoperative morbidity was 13%. One patient needed relaparotomy on day 17 for small bowel obstruction. Median length of hospital stay was 11 days. Postoperatively, two patients developed diabetes. Duodenum-preserving resection of the head of the pancreas represents an organ-preserving principle of surgery. This procedure treats the complications of chronic pancreatitis and provides long-term pain relief in more than 80% of patients.