| 1. |
- Hillier, Ladeana W, et al.
(författare)
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Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution
- 2004
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 432:7018, s. 695-716
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Tidskriftsartikel (refereegranskat)abstract
- We present here a draft genome sequence of the red jungle fowl, Gallus gallus. Because the chicken is a modern descendant of the dinosaurs and the first non-mammalian amniote to have its genome sequenced, the draft sequence of its genome--composed of approximately one billion base pairs of sequence and an estimated 20,000-23,000 genes--provides a new perspective on vertebrate genome evolution, while also improving the annotation of mammalian genomes. For example, the evolutionary distance between chicken and human provides high specificity in detecting functional elements, both non-coding and coding. Notably, many conserved non-coding sequences are far from genes and cannot be assigned to defined functional classes. In coding regions the evolutionary dynamics of protein domains and orthologous groups illustrate processes that distinguish the lineages leading to birds and mammals. The distinctive properties of avian microchromosomes, together with the inferred patterns of conserved synteny, provide additional insights into vertebrate chromosome architecture.
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| 2. |
- Dutz, H, et al.
(författare)
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Experimental check of the Gerasimov-Drell-Hearn sum rule for H-1
- 2004
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Ingår i: Physical Review Letters. - 1079-7114. ; 93:3
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Tidskriftsartikel (refereegranskat)abstract
- For the first time we checked the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the proton experimentally in the photon energy range from 0.2-2.9 GeV with the tagged photon facilities at MAMI (Mainz) and ELSA (Bonn). New data of the doubly polarized total cross section difference are presented in the energy range from 1.6 to 2.9 GeV. The contribution to the GDH integral from 0.2-2.9 GeV yields [254+/-5(stat)+/-12(syst)] mub with negative contributions in the Regge regime at photon energies above 2.1 GeV. This trend supports the validity of the GDH sum rule.
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| 3. |
- Dutz, H, et al.
(författare)
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First measurement of the Gerasimov-Drell-Hearn sum rule for H-1 from 0.7 to 1.8 GeV at ELSA
- 2003
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Ingår i: Physical Review Letters. - 1079-7114. ; 91:19: 192001
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Tidskriftsartikel (refereegranskat)abstract
- To verify the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the first time experimentally, we measured the helicity dependent total photoabsorption cross section with circularly polarized real photons and longitudinally polarized nucleons in the photon energy range 0.68-1.82 GeV with the tagged photon facility at ELSA. The experiment was carried out with a 4pi detection system, a circularly polarized tagged photon beam, and a frozen spin polarized proton target. The contribution to the GDH sum rule in this photon energy range is [49.9+/-2.4(stat)+/-2.2(syst)] mub.
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| 4. |
- Ahrens, J, et al.
(författare)
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First measurement of the helicity-dependent (gamma)over-right-arrow(p)over-right-arrow -> p eta differential cross-section
- 2003
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 17:2, s. 241-244
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Tidskriftsartikel (refereegranskat)abstract
- The helicity dependence of the (γ) over right arrow(p) over right arrow -+ peta reaction has been measured for the first time at a center-of-mass angle theta(eta)*= 70degrees in the photon energy range from 780 MeV to 790 MeV. The experiment, performed at the Mainz microtron MAMI, used a 4pi-detector system, a circularly polarized, tagged photon beam. and a longitudinally polarized frozen-spin target. The helicity 3/2 cross-section is found to be small and the results for helicity 1/2 agree with predictions from the MAID analysis.
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| 5. |
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| 6. |
- Ahrens, J, et al.
(författare)
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Helicity dependence of the (gamma)over-right-arrow (p)over-right-arrow -> n pi(+) pi(0) reaction in the second resonance region
- 2003
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 551:1-2, s. 49-55
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Tidskriftsartikel (refereegranskat)abstract
- The helicity dependence of the total cross section for the (γ) over right arrow(p) over right arrownpi(+) pi(0) reaction has been measured for the first time at incident photon energies from 400 to 800 MeV The measurement was performed with the large acceptance detector DAPHNE at the tagged photon beam facility of the MAMI accelerator in Mainz. This channel is found to be excited predominantly when the photon and proton have a parallel spin orientation, due to the intermediate production of the D-13 resonance. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 7. |
- Ahrens, J, et al.
(författare)
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Helicity dependence of the gamma p -> N pi channels and multipole analysis in the Delta region
- 2004
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 21:2, s. 323-333
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Tidskriftsartikel (refereegranskat)abstract
- A high-quality double-polarization data set for the helicity dependence of the total and differential cross-sections for both gammap --> Npi channels in the Delta region has been obtained in the framework of the GDH experiment. The experiment, performed at the Mainz microtron MAMI, used a 4pi detection system, a circularly polarized photon beam, and a longitudinally polarized frozen-spin target. These data are included in the database to perform a multipole analysis to determine the properties of the Delta(1232)-resonance. For the resonant Delta(1232) multipoles we find a very good agreement with previous analyses, while the nonresonant ones show significant deviations.
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| 8. |
- Starikov, Anton, et al.
(författare)
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Effects of accidental microconstriction on the quantized conductance in long wires
- 2003
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 5023, s. 267-270
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have investigated the conductance of long quantum wires formed in GaAs/ AlxGa1-x As heterostructures. Using realistic fluctuation potentials from donor layers we have simulated numerically the conductance of four different kinds of wires. While ideal wires show perfect quantization, potential fluctuations from random donors may give rise to strong conductance oscillations and degradation of the quantization plateaux. Statistically there is always the possibility of having large fluctuations in a sample that may effectively act as a microconstriction. We therefore introduce microconstrictions in the wires by occasional clustering of donors. These microconstrictions are found to restore the quantized plateaux. A similar effect is found for accidental lithographic inaccuracies.
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| 9. |
- Gadenne, C, et al.
(författare)
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Transient post-mating inhibition of behavioural and central nervous responses to sex pheromone in an insect
- 2001
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Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 268:1476, s. 1631-1635
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Tidskriftsartikel (refereegranskat)abstract
- Mating is costly for both male and female insects and should therefore only occur if it is likely to be successful. Within one scotophase, which is the dark period of the light cycle, male moths can only produce one single spermatophore, which is transferred to the female during mating. Remating within the same scotophase would thus be unsuccessful. We tested the hypothesis that newly mated males of the moth Agrotis ipsilon have developed an energy-saving strategy based on the transient inhibition of their sexual behaviour, thus avoiding unsuccessful remating. Agrotis ipsilon males do not copulate more than once during the same scotophase. Moreover, newly mated males do not respond behaviourally to the female sex pheromone although electroantennograms showed that their peripheral olfactory system is fully functional. However, intracellular recordings of antennal lobe neurons showed that the sensitivity for the synthetic sex pheromone blend decreased as compared with that of unmated males. Both the sexual behaviour and the sensitivity of the antennal lobe neurons were restored when tested during the next scotophase. Our results show a fast, transient neuronal plasticity that 'switches off' the olfactory system, which could prevent males from mating unsuccessfully.
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| 13. |
- Sadek, Medhat M., et al.
(författare)
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Glomerular representation of plant volatiles and sex pheromone components in the antennal lobe of the female Spodoptera littoralis.
- 2002
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Ingår i: Journal of Experimental Biology. - 1477-9145. ; 205:10, s. 1363-1376
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Tidskriftsartikel (refereegranskat)abstract
- We studied the projection patterns of antennal lobe (AL) interneurones sensitive to plant volatiles and female-produced sex pheromone components in the female moth, Spodoptera littoralis. Ten compounds (eight plant-derived compounds and two sex pheromone components) were singly applied to the antenna and, using intracellular recording and staining techniques, the physiological and morphological characteristics of responding neurones were investigated. In addition, ALs stained with a synapsin antibody were optically sectioned using confocal microscopy, and a three-dimensional map of glomeruli in the anterior aspect of the AL was reconstructed. We used the map as a reference for identification of glomeruli innervated by projection neurones (PNs) that respond to plant volatiles and/or pheromone components. Nineteen PNs, responding to one to seven compounds of the ten tested stimuli, were stained with neurobiotin. These neurones each arborised in a single glomerulus in the frontal side of the AL. PNs responding to the same compound arborised in different glomeruli and PNs arborising in the same glomerulus responded to different compounds. Accordingly, glomeruli harbouring the dendritic arborisations of PNs responding to each of the tested compounds constituted a unique array of glomeruli that were not necessarily adjacent. It was thus clear that, at the output level, a single plant volatile or a sex pheromone component was not represented within a single glomerulus in the AL. We expect complex patterns of glomeruli to be involved in the coding of plant-derived compounds, as well as sex pheromone components, in female S. littoralis.
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| 14. |
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