A new instrument for kinetics and branching ratio studies of gas phase collisional processes at very low temperatures.

A new instrument dedicated to the kinetic study of low-temperature gas phase neutral-neutral reactions, including clustering processes, is presented. It combines a supersonic flow reactor with vacuum ultra-violet synchrotron photoionization time-of-flight mass spectrometry. A photoion-photoelectron coincidence detection scheme has been adopted to optimize the particle counting efficiency. The characteristics of the instrument are detailed along with its capabilities illustrated through a few results obtained at low temperatures (<100 K) including a photoionization spectrum of n-butane, the detection of formic acid dimer formation, and the observation of diacetylene molecules formed by the reaction between the C2H radical and C2H2.

Unicondylar knee arthroplasty using cobalt-chromium implants in patients with self-reported cutaneous metal hypersensitivity.

AIMS: The treatment of patients with allergies to metal in total joint arthroplasty is an ongoing debate. Possibilities include the use of hypoallergenic prostheses, as well as the use of standard cobalt-chromium (CoCr) alloy. This non-designer study was performed to evaluate the clinical outcome and survival rates of unicondylar knee arthroplasty (UKA) using a standard CoCr alloy in patients reporting signs of a hypersensitivity to metal. PATIENTS AND METHODS: A consecutive series of patients suitable for UKA were screened for symptoms of metal hypersensitivity by use of a questionnaire. A total of 82 patients out of 1737 patients suitable for medial UKA reporting cutaneous metal hypersensitivity to cobalt, chromium, or nickel were included into this study and prospectively evaluated to determine the functional outcome, possible signs of hypersensitivity, and short-term survivorship at a minimum follow-up of 1.5 years. RESULTS: At a mean follow-up of three years (1.5 to 5.7), no local or systemic symptoms of hypersensitivity to metal were observed. One patient underwent revision surgery to a bicondylar prosthesis due to a tibial periprosthetic fracture resulting in a survival rate of 98.8% (95% confidence interval (CI) 91.7 to 99.8; number at risk, 28) at three years with the endpoint of revision for any reason and a survival rate of 97.6% (95% CI 90.6 to 99.3; number at risk, 29) for the endpoint of all reoperations. Clinical outcome was good to excellent with a mean Oxford Knee Score of 42.5 (sd 2.5; 37 to 48). CONCLUSION: This study is the first demonstrating clinical results and survival analysis of UKA using a CoCr alloy in patients with a history of metal hypersensitivity. Functional outcome and survivorship are on a high-level equivalent to those reported for UKA in patients without a history of metal hypersensitivity. No serious local or systemic symptoms of metal hypersensitivity could be detected, and no revision surgery was performed due to an adverse reaction to metal ions.

Fuzzy regression modeling for tool performance prediction and degradation detection.

In this paper, the viability of using Fuzzy-Rule-Based Regression Modeling (FRM) algorithm for tool performance and degradation detection is investigated. The FRM is developed based on a multi-layered fuzzy-rule-based hybrid system with Multiple Regression Models (MRM) embedded into a fuzzy logic inference engine that employs Self Organizing Maps (SOM) for clustering. The FRM converts a complex nonlinear problem to a simplified linear format in order to further increase the accuracy in prediction and rate of convergence. The efficacy of the proposed FRM is tested through a case study - namely to predict the remaining useful life of a ball nose milling cutter during a dry machining process of hardened tool steel with a hardness of 52-54 HRc. A comparative study is further made between four predictive models using the same set of experimental data. It is shown that the FRM is superior as compared with conventional MRM, Back Propagation Neural Networks (BPNN) and Radial Basis Function Networks (RBFN) in terms of prediction accuracy and learning speed.

Flexible neuro-fuzzy systems.

In this paper, we derive new neuro-fuzzy structures called flexible neuro-fuzzy inference systems or FLEXNFIS. Based on the input-output data, we learn not only the parameters of the membership functions but also the type of the systems (Mamdani or logical). Moreover, we introduce: 1) softness to fuzzy implication operators, to aggregation of rules and to connectives of antecedents; 2) certainty weights to aggregation of rules and to connectives of antecedents; and 3) parameterized families of T-norms and S-norms to fuzzy implication operators, to aggregation of rules and to connectives of antecedents. Our approach introduces more flexibility to the structure and design of neuro-fuzzy systems. Through computer simulations, we show that Mamdani-type systems are more suitable to approximation problems, whereas logical-type systems may be preferred for classification problems.

Recombination can partially substitute for SPO13 in regulating meiosis I in budding yeast.

Recombination and chromosome synapsis bring homologous chromosomes together, creating chiasmata that ensure accurate disjunction during reductional division. SPO13 is a key gene required for meiosis I (MI) reductional segregation, but dispensable for recombination, in Saccharomyces cerevisiae. Absence of SPO13 leads to single-division meiosis where reductional segregation is largely eliminated, but other meiotic events occur relatively normally. This phenotype allows haploids to produce viable meiotic products. Spo13p is thought to act by delaying nuclear division until sister centromeres/chromatids undergo proper cohesion for segregation to the same pole at MI. In the present study, a search for new spo13-like mutations that allow haploid meiosis recovered only new spo13 alleles. Unexpectedly, an unusual reduced-expression allele (spo13-23) was recovered that behaves similarly to a null mutant in haploids but to a wild-type allele in diploids, dependent on the presence of recombining homologs rather than on a diploid genome. This finding demonstrates that in addition to promoting accurate homolog disjunction, recombination can also function to partially substitute for SPO13 in promoting sister cohesion. Analysis of various recombination-defective mutants indicates that this contribution of recombination to reductional segregation requires full levels of crossing over. The implications of these results regarding SPO13 function are discussed.

Evidence that secondary rat Schwann cells in culture maintain their differentiated phenotype.

Schwann cells, on receiving the correct signal, will encircle an axon and wrap it with a myelin sheath. To begin examining some of the mechanisms underlying the process of myelination in vitro, we isolated Schwann cells from the sciatic nerves of neonatal rats and generated large cell populations with cholera toxin. The immunological and biochemical properties of these secondary Schwann cells were characterized after five to seven passages in the absence of axonal contact. These cells continued to express antigens found in both myelinating (P0 and 2',3'-cyclic nucleotide phosphohydrolase) and nonmyelinating cells in vivo (A5E3 and glial fibrillary acidic protein) in addition to the markers common to both types of cells (Ran-1, 217c, S-100, and laminin). Biochemical analyses showed that these cells synthesize the very-long-chain fatty acids (22-26 carbon atoms) found in myelin membranes. Moreover, the enzymes required for the synthesis of myelin glycolipids (including sphingosine acyltransferase, UDP-galactose:ceramide galactosyltransferase, and cerebroside sulfotransferase) were still active, and metabolic labeling studies showed that galactocerebroside and sulfatide were synthesized even though the galactocerebroside pool was insufficient to be detected by immunostaining. Secondary Schwann cells also synthesized four species of myelin basic protein and the major structural glycoprotein in myelin, P0. The pathway necessary for glycosylation of P0 protein remained active, and an analysis of the oligosaccharide chain revealed that approximately 70% was processed to a complex form. In summary, we found that secondary Schwann cells still express most of the immunological markers of differentiated cells and continue to synthesize low levels of myelin components. Therefore, Schwann cells do not dedifferentiate in culture, as previously believed.

[Cooperative osteosarcoma study COSS-77: results after 4 years]. / Kooperative Osteosarkomstudie COSS-77: Ergebnisse nach über 4 Jahren.

71 patients with resectable osterosarcoma received chemotherapy for one year including high-dose methotrexate (18 x 200 mg/kg), adriamycin (5 x [2 x 45] mg/m2) and cyclophosphamide (6 x 1200 mg/m2). During the initial 15 weeks adriamycin was used preferentially and cytostatic agents were applied in a higher frequency than later on. 41/71 patients are continuously free of disease with a median follow up of 39 (24-54) months. The latest appearance of pulmonary metastases was observed at 28 months so far. 18/27 (67%) patients with extension of tumor lesion beyond 1/3 long bones length by x-ray examination relapsed in contrast to 12/43 (28%) patients with smaller lesions. 1 patient died from adriamycin induced cardiomyopathy. Generally therapy was well tolerated. An average of 70-80% of planned drug dosages could be realized without measurable influence of individual differences on outcome.

On bayes risk consistent pattern recognition procedures in a quasi-stationary environment.

Van Ryzin and Greblicki showed that pattern recognition procedures derived from orthogonal series estimates of a probability density function are Bayes risk consistent. In this note it is proved that these procedures do not lose-under some additional conditions-their asymptotic properties even if the random environment is nonstationary.

[Bone marrow transplantation for aplastic anaemia (author's transl)]. / Knochenmarktransplantation bei aplastischer Anämie.

From March 1975 until May 1980 twelve patients with severe aplastic anemia were grafted with bone marrow from HLA-identical siblings by the Munich Cooperative Group for Bone Marrow Transplantation. Six patients are alive between 10 months and more than 5 years after grafting with normal blood values and marrow. One patient is treated as an out patient for chronic localized graft-versus-host disease (GvHD), five patients are well and without treatment. Six patients have died, one patient with a cerebral hemorrhage the day before transplantation, three patients following rejection of grafts 32, 40 and 55 days after grafting, one patient with severe GvHD 85 days after grafting and one patient, probably with interstitial pneumonia, following cerebral hemorrhage. Three of 6 patients who were conditioned with Cyclophosphamide (CY) only died following rejection of the graft. Two adults who were conditioned with CY and "total lymphoid irradiation" and three children, who wer given unirradiated leukocyte concentrates from the marrow donor after grafting, did not reject their grafts. The results of the Munich-Cooperative Group for Bone Marrow Transplantation are comparable to those of large, specialized centers for bone marrow transplantation, they indicate possibilities of cure of severe aplastic anemia by marrow grafts from HLA-identical siblings. They confirm that better results are obtained with earlier transplantation in the course of the disease.