Settling the half-life of 60Fe: fundamental for a versatile astrophysical chronometer.

In order to resolve a recent discrepancy in the half-life of 60Fe, we performed an independent measurement with a new method that determines the 60Fe content of a material relative to 55Fe (t1/2=2.744 yr) with accelerator mass spectrometry. Our result of (2.50±0.12)×10(6) yr clearly favors the recently reported value (2.62±0.04)×10(6) yr, and rules out the older result of (1.49±0.27)×10(6) yr. The present weighted mean half-life value of (2.60±0.05)×10(6) yr substantially improves the reliability as an important chronometer for astrophysical applications in the million-year time range. This includes its use as a sensitive probe for studying recent chemical evolution of our Galaxy, the formation of the early Solar System, nucleosynthesis processes in massive stars, and as an indicator of a recent nearby supernova.

Stable platinum isotope measurements in presolar nanodiamonds by TEAMS.

Nanodiamonds are stardust grains commonly found in primitive meteorites. They survived the formation of the solar system and kept their own individuality. Measurements of trace-element isotopic signatures in these grains will help understanding heavy element nucleosynthesis in massive stars and dust formation from their ejecta. We have continued previous attempts to search for stable Pt isotope anomalies in nanodiamonds via trace element accelerator mass spectrometry (TEAMS). The installation of a new injector beam line at the VERA facility allowed studying low traces of stable elements in different materials. Moreover, recent experiments showed that VERA provides the required measurement precision together with a low Pt machine background. Here, we observed for the first time an indication for enhancements of 198Pt/195Pt isotope ratios in two diamond residues prepared by different chemical separation techniques from the Allende meteorite. Variations in other isotopic ratios were within analytical uncertainty, and no anomaly was identified in a third diamond fraction.

Calcium-41 concentration in terrestrial materials: prospects for dating of pleistocene samples.

Calcium-41 has been suggested as a new tool for radiometric dating in the range of 10(5) to 10(6) years. The concentration of cosmogenic calcium-41 in natural samples of terrestrial origin has now been determined by high-sensitivity accelerator mass spectrometry after pre-enrichment in calcium-41 with an isotope separator. Ratios of calcium-41 to total calcium between 2 x 10(-14) and 3 x 10(-15) were measured for samples of contemporary bovine bone and from limestone deposits. Some prospects for the use of calcium-41 for dating Middle and Late Pleistocene bone and for other geophysical applications are discussed.

Abundance of live ²44Pu in deep-sea reservoirs on Earth points to rarity of actinide nucleosynthesis.

Half of the heavy elements including all actinides are produced in r-process nucleosynthesis, whose sites and history remain a mystery. If continuously produced, the Interstellar Medium is expected to build-up a quasi-steady state of abundances of short-lived nuclides (with half-lives ≤100 My), including actinides produced in r-process nucleosynthesis. Their existence in today's interstellar medium would serve as a radioactive clock and would establish that their production was recent. In particular (244)Pu, a radioactive actinide nuclide (half-life=81 My), can place strong constraints on recent r-process frequency and production yield. Here we report the detection of live interstellar (244)Pu, archived in Earth's deep-sea floor during the last 25 My, at abundances lower than expected from continuous production in the Galaxy by about 2 orders of magnitude. This large discrepancy may signal a rarity of actinide r-process nucleosynthesis sites, compatible with neutron-star mergers or with a small subset of actinide-producing supernovae.

Comparative biotransformation studies of MeIQx and PhIP in animal models and humans.

MeIQx and PhIP are putative carcinogenic heterocyclic amines formed during the cooking of meat and fish. Using accelerator mass spectrometry, we have investigated the metabolism and macromolecule binding of 14C-labelled MeIQx and PhIP in human cancer patients compared to the rat. Following oral administration of MeIQx and PhIP, more DNA adducts were formed in human colon tissue compared with rats. Differences were also observed between rats and humans in the metabolite profile and urine excretion for these compounds. These results suggest humans metabolise heterocyclic amines differently to laboratory rodents and question their use as models of human risk.

X-ray tubes--continuous innovative technology.

The X-ray tube is one of the most important components in any X-ray system. In the beginning, physicists and physicians used gas ion tubes. The so-called Coolidge tube applied a high vacuum and is still used today. Medical examinations have required continuously improved designs of X-ray tubes (smaller focal spots at a higher output). The principle of the Goetze line focus is still applied in any diagnostic X-ray tube. Different anode materials and the rotating anode contributed to an increased output and reduced exposure time. Bearings needed special attention. Spiral groove bearings are the most advanced design today. The heat storage capacity of the anode and the tube housing assembly influences examination time and patient throughput. Cardiac imaging required less motion blurring in cine film images and increasing radiation exposure in interventional procedures called for measures to reduce dose. Protection against radiation and electric shock has always been a concern of design engineers. Focal spot sizes dedicated to specific applications and heat management within the total tube housing assembly will be future issues. Even with the event of ultrasound and MR technology, X-ray procedures will still be applied for diagnostic and interventional purposes.

[The round lung lesion from the clinical viewpoint]. / Der Lungenrundherd aus klinischer Sicht.

The features of about 100 benign nodules are compared with the findings in the same number of peripheral stage I lung carcinomas. There were, indeed, clinical differences between both groups, but the isolated case could practically never be designated malignant or benign with certainty. We thus conclude that each pulmonary nodule has to be resected on the assumption of malignancy without delay.

A critical review of experimental data for the half-lives of the uranium isotopes 238U and 235U.

The existing experimental data for the half-lives of the uranium isotopes 238U and 235U have been scrutinised in detail because of their significant practical importance, in particular for geochronogical use and for the assay of standard samples used for neutron fluence and cross-section measurements. The most accurate measurements by Jaffey et al. (Phys. Rev. C 4 (5) 1889) with 1sigma uncertainties of 0.054% (238U) and 0.068% (235U), are not confirmed by other measurements of comparable accuracy. In this work, we take a critical look at the 238U and 235U half-life measurements in the literature. Although we find that the Jaffey et al. data are concordant with other reliable results, generally much higher uncertainties of the latter cannot prove or disprove the Jaffey et al. results. Therefore, at this time, we do not recommend new half-life values. Instead, we call for new measurements of these two half-lives with accuracies comparable to the work of Jaffey et al.

The first use of (236)U in the general environment and near a shutdown nuclear power plant.

We present a first effort to investigate (236)U in the environment near a shutdown nuclear power plant far away from highly contaminated sites, by using accelerator mass spectrometry. The detection limit of about 1pg (236)U allowed us to identify a minimal increase of the (236)U/(238)U isotopic ratio correlated to a peak of (137)Cs in river sediments downstream of the nuclear power plant, and to detect anthropogenic (236)U also upstream, where it is probably not related to the power plant but to global fallout. The (236)U content shoved variations of the (236)U/(238)U isotopic ratio in relation to the chemical-physical characteristics of the sediments. This demonstrates the potential of (236)U as an environmental tracer, and as an indicator for releases from nuclear facilities.

Calorimetric low temperature detectors for low-energetic heavy ions and their application in accelerator mass spectrometry.

The energy-sensitive detection of heavy ions with calorimetric low temperature detectors was investigated in the energy range of E=0.1-1 MeV/amu, commonly used for accelerator mass spectrometry (AMS). The detectors used consist of sapphire absorbers and superconducting aluminum transition edge thermometers operated at T approximately 1.5 K. They were irradiated with various ion beams (13C, 197Au, 238U) provided by the VERA tandem accelerator in Vienna, Austria. The relative energy resolution obtained was DeltaE/E=(5-9) x 10(-3), even for the heaviest ions such as 238U. In addition, no evidence for a pulse height defect was observed. This performance allowed for the first time to apply a calorimetric low temperature detector in an AMS experiment. The aim was to precisely determine the isotope ratio of 236U/238U for several samples of natural uranium, 236U being known as a sensitive monitor for neutron fluxes. Replacing a conventionally used detection system at VERA by the calorimetric detector enabled to substantially reduce background from neighboring isotopes and to increase the detection efficiency. Due to the high sensitivity achieved, a value of 236U/238U=6.1 x 10(-12) could be obtained, representing the smallest 236U/238U ratio measured at the time. In addition, we contributed to establishing an improved material standard of 236U/238U, which can be used as a reference for future AMS measurements.

Experimental and theoretical evidence for long-lived molecular hydrogen anions H2- and D2-.

The existence of (metastable) molecular hydrogen anions H2(-), D2(-), and H3(-) is demonstrated. These anion species were produced by sputtering of TiH2 and TiD2 targets with Cs+ ions and were identified by accelerator mass spectrometry. From the respective flight times through the spectrometer, lifetimes for H2(-) and D2(-) of at least 3 micros and 4 micros, respectively, can be inferred. Theoretical calculations within the nonlocal resonance model predict the existence of highly rotationally excited anions with lifetimes in the micros range. It is proposed that in sputtering molecular hydrogen species with high rotational and vibrational excitation are formed that are stable on the time scale of the experiment.

[Bronchial carcinoma, dependence of operationsuccess (author's transl)]. / Bronchuskarzinom, Abhängigkeit des Operationserfolges

From 1958 to 1973, 3792 cases of bronchial carcinoma were admitted in our department. 1577 of them could be operated radically. The influence of various factors on the result of the operation is discussed, considering eventual changes in the course of the reported period.

Segment resection for lung cancer.

From 1958 to 1979 1,951 pulmonary resections for lung cancer were performed in our hospital. Segment or wedge resections were carried out in 91 patients, in 34 as palliative operations while in 57, with stage I peripheral carcinoma, the resection was curative. The operative mortality rate for this procedure showed no difference to that for lobectomy at the same stage. The 5-year survival rate for these segment resection patients was 23%, while it was 45% for lobectomy patients. Consequently, segment resection cannot be regarded as a routine method, but rather as an emergency procedure in functionally otherwise inoperable cases.

[Bronchial carcinoma from the surgical viewpoint]. / Das Bronchialkarzinom aus chirurgischer Sicht.

The paper presents the problems of bronchogenic carcinoma and the results of surgical treatment on the basis of 10 000 patients suffering from lung cancer. 20% of all resected cases and 40% of all cases resected during the early stage lived beyond the 5-year survival limit, and during the earliest stage surgical cure can be achieved in 60% to 80% of the patients. Small cell carcinoma is just as operable as all other forms of bronchogenic carcinoma, if in addition chemotherapy and radiotherapy are administered. From the oncological point of view clip or segmental resection are not equivalent to standard lobectomy and must, therefore, remain reserved for functional risk cases. On the basis of cancer biology and in view of the frequently occurring concealed (micro)-metastases we demand adjuvant therapy after every tumor resection; this treatment will consist in immunotherapy during the early stages and in chemo- and radiotherapy during late stages.

[Surgery of bronchus carcinoma (author's transl)]. / Chirurgie des Bronchuscarcinoms.

The results of surgery for bronchial carcinoma can be improved by further stressing of early diagnosis, by operative methods adapted to oncological needs and assessment of techniques which increase operability as well as by adequate and general additional therapy. Based on our material of 8,423 patients of which 2,773 (i.e. 23%) have been operated the results of the operation in relation to type of operation, histology, Feinstein's classification, TNM stages and other are demonstrated.

The mouse and rat MAP1B genes: genomic organization and alternative transcription.

We report the genomic organization of the mouse and rat genes coding for the 2460-amino-acid microtubule-associated protein (MAP) 1B. In addition to seven exons that encode full-length MAP1B, we have identified two alternative exons, exon 3A and the novel exon 3U. We demonstrate that alternative MAP1B transcripts containing either exon 3A or exon 3U are expressed in a variety of mouse and rat tissues at about 1 to 10% of the level of regular transcripts. The alternative transcripts, if translated, would give rise to MAP1B isoforms truncated at the N-terminus. The exon/intron organization underlying the alternative transcripts and the N-terminal amino acid sequence of the putative truncated MAP1B isoforms resemble those of MAP1A, providing further evidence for an evolutionary relationship. The detection of alternative transcripts has implications for the interpretation of conflicting results recently obtained in MAP1B knockout mice.

New half-life measurement of 182Hf: improved chronometer for the early solar system.

The decay of 182Hf, now extinct, into stable 182W has developed into an important chronometer for studying early solar system processes such as the accretion and differentiation of planetesimals and the formation of the Earth and the Moon. The only 182Hf half-life measurements available were performed 40 years ago and resulted in an imprecise half-life of (9+/-2)x10(6) yr. We redetermined the half-life by measuring the specific activity of 182Hf based on two independent methods, resulting in a value of t(1/2)(182Hf)=(8.90+/-0.09)x10(6) yr, in good agreement with the previous value, but with a 20 times smaller uncertainty. The greatly improved precision of this half-life now permits very precise intercalibration of the 182Hf-182W isotopic system with other chronometers.