| 1. |
- Rodriguez, D., et al.
(författare)
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MATS and LaSpec : High-precision experiments using ion traps and lasers at FAIR
- 2010
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Ingår i: The European physical journal. Special topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 183, s. 1-123
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Forskningsöversikt (refereegranskat)abstract
- Nuclear ground state properties including mass, charge radii, spins and moments can be determined by applying atomic physics techniques such as Penning-trap based mass spectrometry and laser spectroscopy. The MATS and LaSpec setups at the low-energy beamline at FAIR will allow us to extend the knowledge of these properties further into the region far from stability. The mass and its inherent connection with the nuclear binding energy is a fundamental property of a nuclide, a unique ""fingerprint"". Thus, precise mass values are important for a variety of applications, ranging from nuclear-structure studies like the investigation of shell closures and the onset of deformation, tests of nuclear mass models and mass formulas, to tests of the weak interaction and of the Standard Model. The required relative accuracy ranges from 10(-5) to below 10(-8) for radionuclides, which most often have half-lives well below 1 s. Substantial progress in Penning trap mass spectrometry has made this method a prime choice for precision measurements on rare isotopes. The technique has the potential to provide high accuracy and sensitivity even for very short-lived nuclides. Furthermore, ion traps can be used for precision decay studies and offer advantages over existing methods. With MATS (Precision Measurements of very short-lived nuclei using an Advanced Trapping System for highly-charged ions) at FAIR we aim to apply several techniques to very short-lived radionuclides: High-accuracy mass measurements, in-trap conversion electron and alpha spectroscopy, and trap-assisted spectroscopy. The experimental setup of MATS is a unique combination of an electron beam ion trap for charge breeding, ion traps for beam preparation, and a high-precision Penning trap system for mass measurements and decay studies. For the mass measurements, MATS offers both a high accuracy and a high sensitivity. A relative mass uncertainty of 10(-9) can be reached by employing highly-charged ions and a non-destructive Fourier-Transform Ion-Cyclotron-Resonance (FT-ICR) detection technique on single stored ions. This accuracy limit is important for fundamental interaction tests, but also allows for the study of the fine structure of the nuclear mass surface with unprecedented accuracy, whenever required. The use of the FT-ICR technique provides true single ion sensitivity. This is essential to access isotopes that are produced with minimum rates which are very often the most interesting ones. Instead of pushing for highest accuracy, the high charge state of the ions can also be used to reduce the storage time of the ions, hence making measurements on even shorter-lived isotopes possible. Decay studies in ion traps will become possible with MATS. Novel spectroscopic tools for in-trap high-resolution conversion-electron and charged-particle spectroscopy from carrier-free sources will be developed, aiming e. g. at the measurements of quadrupole moments and E0 strengths. With the possibility of both high-accuracy mass measurements of the shortest-lived isotopes and decay studies, the high sensitivity and accuracy potential of MATS is ideally suited for the study of very exotic nuclides that will only be produced at the FAIR facility. Laser spectroscopy of radioactive isotopes and isomers is an efficient and model-independent approach for the determination of nuclear ground and isomeric state properties. Hyperfine structures and isotope shifts in electronic transitions exhibit readily accessible information on the nuclear spin, magnetic dipole and electric quadrupole moments as well as root-mean-square charge radii. The dependencies of the hyperfine splitting and isotope shift on the nuclear moments and mean square nuclear charge radii are well known and the theoretical framework for the extraction of nuclear parameters is well established. These extracted parameters provide fundamental information on the structure of nuclei at the limits of stability. Vital information on both bulk and valence nuclear properties are derived and an exceptional sensitivity to changes in nuclear deformation is achieved. Laser spectroscopy provides the only mechanism for such studies in exotic systems and uniquely facilitates these studies in a model-independent manner. The accuracy of laser-spectroscopic-determined nuclear properties is very high. Requirements concerning production rates are moderate; collinear spectroscopy has been performed with production rates as few as 100 ions per second and laser-desorption resonance ionization mass spectroscopy (combined with beta-delayed neutron detection) has been achieved with rates of only a few atoms per second. This Technical Design Report describes a new Penning trap mass spectrometry setup as well as a number of complementary experimental devices for laser spectroscopy, which will provide a complete system with respect to the physics and isotopes that can be studied. Since MATS and LaSpec require high-quality low-energy beams, the two collaborations have a common beamline to stop the radioactive beam of in-flight produced isotopes and prepare them in a suitable way for transfer to the MATS and LaSpec setups, respectively.
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| 2. |
- Martrat, Griselda, et al.
(författare)
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Exploring the link between MORF4L1 and risk of breast cancer
- 2011
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Ingår i: Breast Cancer Research. - : Springer Science and Business Media LLC. - 1465-5411 .- 1465-542X. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Proteins encoded by Fanconi anemia (FA) and/or breast cancer (BrCa) susceptibility genes cooperate in a common DNA damage repair signaling pathway. To gain deeper insight into this pathway and its influence on cancer risk, we searched for novel components through protein physical interaction screens. Methods: Protein physical interactions were screened using the yeast two-hybrid system. Co-affinity purifications and endogenous co-immunoprecipitation assays were performed to corroborate interactions. Biochemical and functional assays in human, mouse and Caenorhabditis elegans models were carried out to characterize pathway components. Thirteen FANCD2-monoubiquitinylation-positive FA cell lines excluded for genetic defects in the downstream pathway components and 300 familial BrCa patients negative for BRCA1/2 mutations were analyzed for genetic mutations. Common genetic variants were genotyped in 9,573 BRCA1/2 mutation carriers for associations with BrCa risk. Results: A previously identified co-purifying protein with PALB2 was identified, MRG15 (MORF4L1 gene). Results in human, mouse and C. elegans models delineate molecular and functional relationships with BRCA2, PALB2, RAD51 and RPA1 that suggest a role for MRG15 in the repair of DNA double-strand breaks. Mrg15-deficient murine embryonic fibroblasts showed moderate sensitivity to g-irradiation relative to controls and reduced formation of Rad51 nuclear foci. Examination of mutants of MRG15 and BRCA2 C. elegans orthologs revealed phenocopy by accumulation of RPA-1 (human RPA1) nuclear foci and aberrant chromosomal compactions in meiotic cells. However, no alterations or mutations were identified for MRG15/MORF4L1 in unclassified FA patients and BrCa familial cases. Finally, no significant associations between common MORF4L1 variants and BrCa risk for BRCA1 or BRCA2 mutation carriers were identified: rs7164529, P-trend = 0.45 and 0.05, P-2df = 0.51 and 0.14, respectively; and rs10519219, P-trend = 0.92 and 0.72, P-2df = 0.76 and 0.07, respectively. Conclusions: While the present study expands on the role of MRG15 in the control of genomic stability, weak associations cannot be ruled out for potential low-penetrance variants at MORF4L1 and BrCa risk among BRCA2 mutation carriers.
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| 3. |
- Reinhard, H, et al.
(författare)
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Endothelial progenitor cells in long-standing asymptomatic type 1 diabetic patients with or without diabetic nephropathy
- 2011
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Ingår i: Nephron. Clinical practice. - : S. Karger AG. - 1660-2110. ; 118:3, s. C309-C314
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Tidskriftsartikel (refereegranskat)abstract
- A decrease in the number and dysfunction of endothelial progenitor cells (EPC) may increase the risk for progression of cardiovascular disease (CVD) in type 1 diabetic patients with diabetic nephropathy (DN). Our aim was to evaluate EPC numbers in asymptomatic CVD type 1 diabetic patients with or without DN and to study the effect of CVD and medication on EPC numbers. <i>Methods:</i> We examined EPC numbers in 37 type 1 diabetic patients with DN and 35 type 1 diabetic patients with long-standing normoalbuminuria. Patients were without symptoms of CVD and the prevalence of CVD was previously shown to be very low. EPC number was assessed in in vitro cultures by fluorescent staining of attached cells. <i>Results:</i> There was no difference in EPC numbers between patients with DN (mean ± SD 120 ± 49 cells/field) and normoalbuminuria (108 ± 41 cells/field; p = 0.25). Furthermore, EPC number was not associated with CVD (p > 0.05). Conventional risk factors were significantly higher in patients with DN and they received more CVD-preventive treatment. All patients receiving simvastatin or calcium-channel blockers had higher numbers of EPC compared to patients not treated with these drugs. <i>Conclusions:</i> Asymptomatic patients with DN had EPC numbers similar to normoalbuminuric patients, which was related to aggressive CVD intervention therapy. This may have contributed to the low prevalence of CVD.
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| 4. |
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| 5. |
- Stiller, Krystyna Marta, 1947, et al.
(författare)
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Atom probe tomography of oxide scales
- 2013
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Ingår i: Oxidation of Metals. - : Springer Science and Business Media LLC. - 1573-4889 .- 0030-770X. ; 79:3-4, s. 227-238
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Tidskriftsartikel (refereegranskat)abstract
- Atom probe tomography, APT, is the only microstructural method that can routinely analyse and position individual atoms in a material with a spatial resolution of 0.1-0.5 nm. Recent implementation of pulsed-laser to APT made investigation of less conducting materials, such as oxides, feasible. In this paper a short description of the principle of the techniques is presented, followed by examples of recent APT studies of thermally grown oxide scales produced on alumina formers (Pt-modified NiAl diffusion coating and FeCrAl alloy), at the crack tips in a Ni-based alloy and on a Zr-alloy. Additionally, results from preliminary studies of ZnO and MgO bulk materials are shown. The obtained information on the atomic scale about the chemistry variations in the scales and at the metal oxide interfaces provides valuable insights into oxidation processes. © 2012 Springer Science+Business Media New York.
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| 6. |
- Werren, John H, et al.
(författare)
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Functional and evolutionary insights from the genomes of three parasitoid Nasonia species.
- 2010
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 327:5963, s. 343-8
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Tidskriftsartikel (refereegranskat)abstract
- We report here genome sequences and comparative analyses of three closely related parasitoid wasps: Nasonia vitripennis, N. giraulti, and N. longicornis. Parasitoids are important regulators of arthropod populations, including major agricultural pests and disease vectors, and Nasonia is an emerging genetic model, particularly for evolutionary and developmental genetics. Key findings include the identification of a functional DNA methylation tool kit; hymenopteran-specific genes including diverse venoms; lateral gene transfers among Pox viruses, Wolbachia, and Nasonia; and the rapid evolution of genes involved in nuclear-mitochondrial interactions that are implicated in speciation. Newly developed genome resources advance Nasonia for genetic research, accelerate mapping and cloning of quantitative trait loci, and will ultimately provide tools and knowledge for further increasing the utility of parasitoids as pest insect-control agents.
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