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[en] A Carleman estimate for a certain first order elliptic system is proved. The proof is elementary and does not rely on pseudo-differential calculus. This estimate is used to prove Carleman estimates for the isotropic Lame system as well as for the isotropic Maxwell system with C1 coefficients
[en] In (ns-np)-excitation of alkali atoms by polarized electrons some of the spin orientation of the primary electron beam is transferred to the excited atoms because of exchange collisions. In the present work the polarization transfer to Na, K, Rb, and Cs respectively is studied by looking for the circular light polarization transfer of (np-ns)-decay radiation emitted in forward direction following impact excitation by a beam of longitudinally polarized electrons. Maximum polarization transfers are observed at collision energies with values about 1.5 times that of np-thresholds. The transfer increases with increasing atomic number. In case of (6s-6p)-excitation of cesium 45% of primary electron spin polarization is transferred to the atoms at maximum. The agreement with available close coupling data is statisfactory. (orig.)
[en] A new target and ion source unit has been developed at CERN-ISOLDE with the aim of delivering isobarically clean beams of short lived neutron-rich Cd and Zn. A quartz insert in the transfer line allows the retention and the decay of alkali contaminants by controlling its temperature from 308 deg. C to 792 deg. C. This paper presents the design of this transfer line. New alkali suppression factors are deduced from 80Rb, 8Li, 46K and 126,142Cs yield measurements. The enthalpy of adsorption for Rb and Cs is calculated from 80Rb and 126Cs suppression factors. The yield of 77Ga and 96Sr are presented.
[en] We prove exact controllability for Maxwell's system with variable coefficients in a bounded domain by a current flux in the boundary. The proof relies on a duality argument which reduces the proof of exact controllability to the proof of continuous observability for the homogeneous adjoint system. There is no geometric restriction imposed on the domain
[en] Full text: At ISOLDE, radioactive nuclides are produced in thick high-temperature targets via spallation, fission or fragmentation reactions. The targets and proton-neutron converters are placed in the external proton beam of the CERN PS-Booster, which delivers pulses with an intensity up to 3.0 x 1013 protons of 1.4 GeV kinetic energy at 1.2 s intervals. Observations of ISOLDE targets and cylindrical tantalum rods used as spallation neutron sources irradiated with about 6 x 1018 protons showed major deformations, dislodgements and damage leading to this investigation of thermal stress and shock wave effects. A laser doppler vibrometer based technique has been developed to investigate the reaction of target materials by measuring the surface velocity and displacement of solid targets induced by 230 ns resp. 2.3 μs proton pulses under precisely defined beam parameters. The radial surface velocity of solid cylindrical targets was recorded with a laser doppler vibrometer up to 40 m away from the interaction point to protect the laser detector against radiation damage. The energy deposition in the different target materials was estimated by Monte-Carlo simulations with MARS-Code. In the following we show the measurement principle and the observed vibration modes of cylindrical target geometries, describe the experiments at the ISOLDE HRS front-end and at the CERN Super-Proton Synchrotron (SPS), and discuss the calculations and measurement results. The potential application of this experimental technique for the development and improvement of ISOLDE targets and proton-neutron converters as well as for diagnostic and survey of solid targets to other high power targets (i.e. CNGS and NuFact) is discussed. (author)
[en] We describe an innovative mode for localizing surface molecules. In this methodology, individual C60 impacts at 50 keV are localized using an electron emission microscope, EEM, synchronized with a time-of-flight mass spectrometer for the detection of the concurrently emitted secondary ions. The instrumentation and methodologies for generating ion maps are presented. The performance of the localization scheme depends on the characteristics of the electron emission, those of the EEM and of the software solutions for image analysis. Using 50 keV C60 projectiles, analyte specific maps and maps of co-emitted species have been obtained. The individual impact sites were localized within 1-2 μm. A distinctive feature of recording individual impacts is the ability to identify co-emitted ions which originate from molecules co-located within ∼10 nm
[en] Early diagnosis gives melanoma patients the best chance for long term survival. However discrimination of an early melanoma from an unusual/atypical benign nevus can represent a significant challenge. There are no current pathological markers to definitively define malignant potential in these indeterminate lesions. Thus, there is a need for improved diagnostic tools. Chromosomal instability (CIN) is a hallmark of cancer and is markedly prevalent in melanoma. Advances in genomic have opened the door for the development of molecular tools to better segregate benign and malignant lesions. This paper focuses on CIN in melanoma and the role of current diagnostic approaches.
[en] Isotope yields at ISOLDE are regularly measured online (with dedicated gamma and beta detectors) and off line by implantation and subsequent alpha-, beta- or gamma spectroscopy. The Java based measurement software, dedicated to tape station measurements, has been updated in order to automate yield measurements and provide possibilities to repeat existing measurements. A procedure supported by dedicated programs was established to analyze data. The results are centrally stored and provide an interface to the existing ISOLDE yield database. The present ISOLDE yield database has been recently created and updated with a large number of yields compiled from published data. The database developed on ORACLE guarantees reliability and security and provides a simple way of compiling new information. A user oriented interface has been programmed allowing accessing the information via a web browser. Several levels in the database structure provide selective access to different layers of technical information for advanced users and for technical R and D. The improvements in the yield measurement procedure, the data storage and accessibility, as well as the new database structure, the web application and the access interfaces, enhance the communication between technical information like yields and the users of the ISOLDE facility.
[en] Germ cell protein expression in melanoma has been shown to correlate with malignancy, severity of disease and to serve as an immunologic target for therapy. However, very little is known about the role that germ cell proteins play in cancer development. Unique germ cell pathways include those involved in immortalization, genetic evolution, and energy metabolism. There is an ever increasing recognition that within tumors there is a subpopulation of cells with stem-cell-like characteristics that play a role in driving tumor genesis. Stem cell and germ cell biology is intertwined. Given the enormous potential and known expression of germ cell proteins in melanoma, it is possible that they represent a largely untapped resource that may play a fundamental role in tumor development and progression. The purpose of this paper is to provide an update on the current value of germ cell protein expression in melanoma diagnosis, prognosis, and therapy, as well as to review critical germ cell pathways and discuss the potential roles these pathways may play in malignant transformation
[en] Melanomas demonstrate chromosomal instability (CIN). In fact, CIN can be used to differentiate melanoma from benign nevi. The exact molecular mechanisms that drive CIN in melanoma have yet to be fully elucidated. Cancer/testis antigens are a unique group of germ cell proteins that are found to be primarily expressed in melanoma as compared to benign nevi. The abnormal expression of these germ cell proteins, normally expected only in the testis and ovaries, in somatic cells may lead to interference with normal cellular pathways. Germ cell proteins that may be particularly critical in CIN are meiosis proteins. Here, we review pathways unique to meiosis with a focus on how the aberrant expression of meiosis proteins in normal mitotic cells "meiomitosis"could impact chromosomal instability in melanoma and other cancers.