An upgraded high-velocity dust particle accelerator at Concordia College in Moorhead, Minnesota

In 1975, Concordia College in Moorhead, Minnesota acquired a 2 MeV dust particle accelerator from NASA/GSFC that was used to test the lunar ejecta and micrometeorite (LEAM) experiment flown on Apollo 17. This high-speed dust particle accelerator is still fully functional and is currently being upgraded. Improvements to the electronic detection system have been undertaken including a computer-based, data acquisition system and new particle detection sensor electronics. These sensors have additional amplifiers that extend the range of charge detection to 1×10⁻¹² C allowing for the detection of larger particles. Improvements to the vacuum system have also been made. The accelerator beam line is now pumped with an oil-free, turbomolecular pump reducing possible problems with hydrocarbon contamination. In this work, we describe the facility, and outline some of the recent improvements to the dust particle accelerator and discuss its capabilities and limitations. We also summarize some of the recent experiments conducted using the facility.     

Techniques for monitoring protein misfolding and aggregation in vitro and in living cells

Protein misfolding and aggregation have been considered important in understanding many neurodegenerative diseases and recombinant biopharmaceutical production. Various traditional and modern techniques have been utilized to monitor protein aggregation in vitro and in living cells. Fibril formation, morphology and secondary structure content of amyloidogenic proteins in vitro have been monitored by molecular probes, TEM/AFM, and CD/FTIR analyses, respectively. Protein aggregation in living cells has been qualitatively or quantitatively monitored by numerous molecular folding reporters based on either fluorescent protein or enzyme. Aggregation of a target protein is directly correlated to the changes in fluorescence or enzyme activity of the folding reporter fused to the target protein, which allows non-invasive monitoring aggregation of the target protein in living cells. Advances in the techniques used to monitor protein aggregation in vitro and in living cells have greatly facilitated the understanding of the molecular mechanism of amyloidogenic protein aggregation associated with neurodegenerative diseases, optimizing culture conditions to reduce aggregation of biopharmaceuticals expressed in living cells, and screening of small molecule libraries in the search for protein aggregation inhibitors.     

Comparison of autologous bone marrow transplantation and intensive chemotherapy as postremission therapy in adult acute myeloid leukemia. The Groupe Ouest Est Leucémies Aigu?s Myéloblastiques (GOELAM)

Three intensive consolidation strategies are currently proposed to younger adults with acute myeloid leukemia (AML) in first complete remission (CR): allogeneic or autologous bone marrow transplantation (BMT) and intensive consolidation chemotherapy (ICC). Patients aged 15 to 50 years with de novo AML received an induction treatment with 7 days of cytarabine and either idarubicin or rubidazone. After achievement of a CR, patients up to the age of 40 and having an HLA-identical sibling were assigned to undergo an allogeneic BMT. All the other patients received a first course of ICC with high-dose cytarabine and the same anthracycline as for induction. They were then randomly assigned to either receive a second course of ICC with amsacrine and etoposide or a combination of busulfan and cyclosphosphamide followed by an unpurged autologous BMT. Of 517 eligible patients, 367 had a CR, but only 219 (59.5%) actually received the planned intensive postremission treatment (73 allogeneic BMT, 75 autologous BMT, and 71 ICC). With a median follow-up of 62 months, the 4-year disease-free survival (DFS) of the 367 patients in CR was 39.5%. The 4-year overall survival (OS) of the 517 eligible patients was 40.5%. In multivariate analysis, DFS and OS were influenced only by the initial white blood cell count and by the French-American-British classification. The type of postremission therapy had no significant impact on the outcome. There was no difference in the 4-year DFS and OS between 88 patients for whom an allogeneic BMT was scheduled (respectively, 44% and 53%) and 134 patients of the same age category and without an HLA-identical sibling (respectively, 38% and 53%). Similarly, there was no difference in the outcome between autologous BMT and ICC. The 4-year DFS was 44% for the 86 patients randomly assigned to autologous BMT and 40% for the 78 patients assigned to ICC (P = .41). The 4-year OS was similar in the two groups (50% v 54.5%, P = .72). The median duration of hospitalization and thrombocytopenia were longer after autologous BMT (39 v 32 days, P = .006, and 109.5 v 18.5 days, P = .0001, respectively). After a first course of ICC, a second course of chemotherapy is less myelotoxic than an unpurged autologous BMT but yields comparable DFS and OS rates.     

Parallel correlated double sampling technique for pipelined analogue-to-digital converters

A new correlated double sampling technique that avoids the additional thermal noise penalty is presented. The new technique employs a low- gain two-stage opamp with the second stage made up of multiple gain stages in parallel. The superior noise performance of the proposed technique to correlated double sampling is shown.     

Three-dimensional analysis of a compression test on stone wool

A full three-dimensional (3D) study of a compression test on a sample made of stone wool is presented. The analysis combines different tools, namely X-ray microtomography of an in situ experiment, image acquisition and treatment, and volume correlation. This set of tools allows for the measurement of 3D displacement fields and enables Poisson’s ratio of this type of material to be evaluated. The strain fields are used to analyze localization phenomena. The uncertainty of the analysis is evaluated by actually moving the sample in its undeformed and deformed states, qualifying both image acquisition and correlation steps.     

Global spatial and temporal distribution of vegetation fire as determined from satellite observations

Vegetation fires occur worldwide, all year round and inject enormous amounts of trace gases and particles into the atmosphere. Nonetheless, there is still great uncertainty as to the global spatial and temporal distribution of vegetation fires. Twenty one months of global, daily, daytime satellite data at 1 km resolution, from April 1992 to December 1993, were processed in order to determine the positions of active vegetation fires. Results from the first twelve months of the study period are presented here. This is the first time that such a global study has been carried out using a long time series data set and a single processing technique. The data set and results discussed provide much improved information on the spatial variability and the seasonality of vegetation fires. They will be of use in the global mapping and modelling of emissions due to biomass burning as well as in the study of the role of fire in land cover maintenance and change. We show that half of the fires detected were on the African continent and over 70% within the tropical belt. Fires were detected in more than 6% of 1 km² pixels, over land, during the 12-month period and savanna grasslands accounted for over one third of this area.     

Nitrogen impurity effects on nickel silicide formation at low temperatures - New “nitrogen co-plasma” approach

Nickel based silicide films were prepared by annealing nickel-platinum layers deposited on n doped Si substrates. We report on the evolution of the phase formation and the redistribution of contaminants on blanket wafers during silicide formation as a function of the nitrogen gas flow introduces during Ni(Pt) deposition. Nitrogen incorporation creates a contamination as-deposited layer which modifies phase formation and changes nickel diffusion. Nitrogen is not incorporated in silicide formed. After a second anneal, the monosilicide forms excepted for high nitrogen quantity introduced where the Ni₃Si₂ is always observed. Monosilicide thermal stability is also improved by nitrogen co-plasma.     

Defensive secretion of the carabid beetlePasimachus subsulcatus

The defensive secretion of the carabid beetlePasimachus subsulcatus is a concentrated solution (up to 90%) of carboxylic acids, amounting to about 1% of body mass. It contains three major components (methacrylic, tiglic, and angelic acids) and four minor components (isobutyric, 2-methyl-butyric, isovaleric, and senecioic acids). In the single population of this large flightless beetle that was examined, the relative ratio of acidic components was remarkably constant from individual to individual.Report No. 87 of the series Defense Mechanisms of Arthropods; No. 86 is Dussourd, D., et al.,Proc. Natl. Acad. Sci. 85, 5992 (1988).