Ion microbeam radiation system

An ion microbeam radiation test system has been built for studying radiation-induced charge collection and single event upsets in advanced semiconductor circuits. With this system, it is possible to direct an ion beam of a diameter as small as 1 μm onto a circuit or test structure with a placement accuracy of 1 μm. The components of the system and its operation are described. Applications are described which demonstrate the capabilities of the system     

Scalar equations for synchronous Boolean networks with biological applications

One way of coping with the complexity of biological systems is to use the simplest possible models which are able to reproduce at least some nontrivial features of reality. Although two value Boolean models have a long history in technology, it is perhaps a little bit surprising that they can also represent important features of living organizms. In this paper, the scalar equation approach to Boolean network models is further developed and then applied to two interesting biological models. In particular, a linear reduced scalar equation is derived from a more rudimentary nonlinear scalar equation. This simpler, but higher order, two term equation gives immediate information about both cycle and transient structure of the network.     

Thermoelectric charge imbalance in superconducting aluminum

The charge imbalance voltage produced in superconducting aluminum by the presence of a temperature gradient and an electric current has been studied over the temperature range 0.5–1.2 K. Measurements were obtained of the magnitude and temperature dependence of the charge imbalance voltage of seven samples, two of which contained magnetic impurities. The data are compared with recent theoretical models of the effect.Research sponsored by NSF grant DMR 78-09428.     

Bone marrow stromal cells constitutively express high levels of cytochrome P4501B1 that metabolize 7,12-dimethylbenz[a]anthracene

The polycyclic aromatic hydrocarbon 7,12-dimethylbenz[a]anthracene (DMBA) is a potent carcinogen that produces immunotoxic effects in bone marrow. Here, we show that bone marrow stromal cells metabolize DMBA to such products as 3,4-dihydrodiol, the precursor to the most mutagenic DMBA metabolite. The BMS2 bone marrow stromal cell line constitutively expressed higher levels of CYP1B1 protein and mRNA than C3H10T1/2 mouse embryo fibroblasts. BMS2 cells also produced a DMBA metabolite profile that was consistent with CYP1B1 activity. Treatment with the potent aryl hydrocarbon receptor (AhR) ligand 2,3, 7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced a approximately 2-fold increase in CYP1B1 mRNA, protein, and activity in BMS2 cells. Two forms of the AhR (97 and 104 kDa) and the AhR nuclear translocator were detected in BMS2 cells. The AhR translocated to the nucleus after treatment with TCDD or DMBA but was approximately 5 times slower with DMBA. Primary bone marrow stromal (BMS) cell cultures established from AhR-/- mice showed similar basal CYP1B1 expression and activity as cell cultures established from heterozygous littermates or C57BL/6 mice. However, primary BMS cells from AhR-/- mice did not exhibit increased CYP1B1 protein expression after incubation with TCDD. BMS cells therefore constitutively express functional CYP1B1 that is not dependent on the AhR. This contrasts with embryo fibroblasts from the same mouse strain, in which basal CYP1B1 expression is AhR dependent. We therefore conclude that bone marrow toxicity may be mediated by CYP1B1-dependent DMBA metabolism, which is regulated by factors other than the AhR.     

A 1.0-GHz single-issue 64-bit powerPC integer processor

The organization and circuit design of a 1.0 GHz integer processor built in 0.25 μm CMOS technology are presented, a microarchitecture emphasizing parallel computation with a single late select per cycle, structured control logic implemented by read-only-memories and programmable logic arrays, and a delayed reset dynamic circuit style enabling complex functions to be implemented in a few levels of logic are among the key design choices described. A means for at-speed scan testing of this high-frequency processor by a low-speed tester is also presented     

The public health physician and bacteriologist Heinrich Wilhelm Conradi (1876-1943). His fate during national socialism

At present, urinary vanillylmandelic acid (VMA) and/or homovanillic acid (HVA), metabolites of catecholamines, are the most sensitive diagnostic markers of neuroblastoma. They can be measured by the high-performance liquid chromatographic method, which has been used to screen for neuroblastoma in infants in Japan. From 6486 urine samples of 18-month-old children, 103 samples showed high HVA levels over the cutoff point for neuroblastoma, and most of them also showed markedly high levels of 5-hydroxyindoleacetic acid (5-HIAA), a metabolite of serotonin. One of the causes of high HVA excretion might be due to the ingestion of banana, common weaning food in early childhood. Our study showed that it is better to restrict banana ingestion within 24 hours before taking a urine sample for diagnosis of neuroblastoma and that 5-HIAA is a good marker of a pseudopositive result due to banana ingestion.     

Electron beam testing of circuits at liquid nitrogen temperature

An electron beam tester has been modified so that circuits being tested can be cooled to liquid nitrogen temperature. This enables voltage contrast imaging, and internal node probing, of low-temperature circuits. Waveform measurements made in this way reveal details of low-temperature circuit operation which cannot be easily obtained by any other means.     

„...in erster Linie nur um das Wohl und Wehe der Zahnärzte“ – „Reichszahnärzteführer“ Ernst Stuck (1893–1974)

NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin - From the very beginning German dentists and their scientific and professional organizations were involved in the...