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Author |
Peris, J.B.; Davis, P.; Cuevas, J.M.; Nebot, M.; Sanjuan, R. |
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Title |
Distribution of Fitness Effects Caused by Single-Nucleotide Substitutions in Bacteriophage f1 |
Type |
Journal Article |
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Year |
2010 |
Publication |
Genetics |
Abbreviated Journal |
Genetics |
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Volume |
185 |
Issue |
2 |
Pages |
603-U308 |
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Abstract |
Empirical knowledge of the fitness effects of mutations is important for understanding many evolutionary processes, yet this knowledge is often hampered by several sources of measurement error and bias. Most of these problems can be solved using site-directed mutagenesis to engineer single mutations, an approach particularly suited for viruses due to their small genomes. Here, we used this technique to measure the fitness effect of 100 single-nucleotide substitutions in the bacteriophage f1, a filamentous single-strand DNA virus. We found that approximately one-fifth of all mutations are lethal. Viable ones reduced fitness by 11% on average and were accurately described by a log-normal distribution. More than 90% of synonymous substitutions were selectively neutral, while those affecting intergenic regions reduced fitness by 14% on average. Mutations leading to amino acid substitutions had an overall mean deleterious effect of 37%, which increased to 45% for those changing the amino acid polarity. Interestingly, mutations affecting early steps of the infection cycle tended to be more deleterious than those affecting late steps. Finally, we observed at least two beneficial mutations. Our results confirm that high mutational sensitivity is a general property of viruses with small genomes, including RNA and single-strand DNA viruses infecting animals, plants, and bacteria. |
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Address |
[Peris, Joan B.; Davis, Paulina; Cuevas, Jose M.; Sanjuan, Rafael] Univ Valencia, Inst Cavanilles Biodiversitat & Biol Evolut, Valencia 46980, Spain, Email: rafael.sanjuan@uv.es |
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Genetics Soc Am |
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English |
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ISSN |
0016-6731 |
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Notes |
ISI:000281905200017 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
383 |
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Author |
Rodriguez, D. et al; Algora, A.; Rubio, B.; Tain, J.L. |
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Title |
MATS and LaSpec: High-precision experiments using ion traps and lasers at FAIR |
Type |
Journal Article |
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Year |
2010 |
Publication |
European Physical Journal-Special Topics |
Abbreviated Journal |
Eur. Phys. J.-Spec. Top. |
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Volume |
183 |
Issue |
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Pages |
1-123 |
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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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Address |
[Rodriguez, D.; Lallena, A. M.] Univ Granada, Dept Fis Atom Mol & Nucl, E-18071 Granada, Spain, Email: danielrodriguez@ugr.es |
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Publisher |
Springer Heidelberg |
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English |
Summary Language |
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Original Title |
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Edition |
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ISSN |
1951-6355 |
ISBN |
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Notes |
ISI:000280061400001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
412 |
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Author |
Warnecke, S.; Sevryuk, M.B.; Ceperley, D.M.; Toennies, J.P.; Guardiola, R.; Navarro, J. |
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Title |
The structure of para-hydrogen clusters |
Type |
Journal Article |
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Year |
2010 |
Publication |
European Physical Journal D |
Abbreviated Journal |
Eur. Phys. J. D |
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Volume |
56 |
Issue |
3 |
Pages |
353-358 |
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Abstract |
The path integral Monte Carlo calculated radial distributions of para-hydrogen clusters (p-H-2) N consisting of N = 4-40 molecules interacting via a Lennard-Jones potential at T = 1.5 K show evidence for additional peaks compared to radial distributions calculated by diffusion Monte Carlo (T = 0 K) and path integral Monte Carlo at T <= 0.5 K. The difference in structures is attributed to quantum delocalization at the lowest temperature. The new structures at finite temperatures appear to be consistent with classical structures calculated for an effective Morse potential, which in order to account for the large zero point energy, is substantially softer than the Lennard-Jones potential. |
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Address |
[Warnecke, S.; Sevryuk, M. B.; Toennies, J. P.] Max Planck Inst Dynam & Self Org, D-37073 Gottingen, Germany, Email: navarro@ific.uv.es |
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Publisher |
Springer |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1434-6060 |
ISBN |
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Notes |
ISI:000274327600008 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
505 |
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Author |
CDF Collaboration (Aaltonen, T. et al); Cabrera, S.; Cuenca Almenar, C. |
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Title |
Study of multi-muon events produced in p (p)over-bar interactions at root s=1.96 TeV |
Type |
Journal Article |
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Year |
2010 |
Publication |
European Physical Journal C |
Abbreviated Journal |
Eur. Phys. J. C |
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Volume |
68 |
Issue |
1-2 |
Pages |
109-118 |
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Abstract |
We report the results of a study of multi-muon events produced at the Fermilab Tevatron collider and acquired with the CDF II detector using a dedicated dimuon trigger. The production cross section and kinematics of events in which both muon candidates are produced inside the beam pipe of radius 1.5 cm are successfully modeled by known processes which include heavy flavor production. In contrast, we are presently unable to fully account for the number and properties of the remaining events, in which at least one muon candidate is produced outside of the beam pipe, in terms of the same understanding of the CDF II detector, trigger, and event reconstruction. |
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Address |
[Chen, Y. C.; Hou, S.; Mitra, A.; Teng, P. K.; Tsai, S. -Y.; Wang, S. M.] Acad Sinica, Inst Phys, Taipei, Taiwan, Email: ptohos@fnal.gov |
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Springer |
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English |
Summary Language |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1434-6044 |
ISBN |
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Area |
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Conference |
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Notes |
ISI:000279843400004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
280 |
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Author |
Batist, L.; Gorska, M.; Grawe, H.; Janas, Z.; Kavatsyuk, M.; Karny, M.; Kirchner, R.; La Commara, M.; Mukha, I.; Plochocki, A.; Roeckl, E. |
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Title |
Systematics of Gamow-Teller beta decay “Southeast” of Sn-100 |
Type |
Journal Article |
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Year |
2010 |
Publication |
European Physical Journal A |
Abbreviated Journal |
Eur. Phys. J. A |
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Volume |
46 |
Issue |
1 |
Pages |
45-53 |
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Keywords |
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Abstract |
The energy centroids and integrated strengths of Gamow-Teller transitions in the beta(+) and electron-capture decay are analyzed for nuclei whose proton number Z and neutron number N are restricted to 44 <= Z <= 50 and 50 <= N <= 58. The analysis is based on data measured both with high-resolution gamma-ray spectrometry and total gamma-ray absorption techniques. The dependence of the considered quantities on the relative neutron excess are established after taking into account the effects due to the Coulomb interaction and mean-field level occupancies. An extrapolation of this dependence to the lightest known tin isotopes is used to estimate the decay characteristics of Sn-100 and Sn-101. The values extrapolated for the half-lives of Sn-100 and Sn-101 agree with experimental data. Using the extrapolated values together with shell model predictions, the Q values for the electron-capture decay of Sn-100 is evaluated. The quenching factor for beta(+) and the electron-capture decay of the nuclei under consideration here is established to be 0.56(2) with a possible weak dependence on N – Z. |
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Address |
[Batist, L.] St Petersburg Nucl Phys Inst, RU-188350 Gatchina, Russia, Email: batist@pnpi.spb.ru |
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Publisher |
Springer |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1434-6001 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
ISI:000282433500005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
258 |
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