| 1. |
- Wijesooriya, K, et al.
(författare)
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Polarization measurements in high-energy deuteron photodisintegration
- 2001
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 86:14, s. 2975-2979
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Tidskriftsartikel (refereegranskat)abstract
- We present measurements of the recoil proton polarization for the d(γ⃗,p⃗)n reaction at θc.m. = 90° for photon energies up to 2.4 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. The induced polarization py vanishes above 1 GeV, contrary to meson-baryon model expectations, in which resonances lead to large polarizations. However, the polarization transfer Cx does not vanish above 1 GeV, inconsistent with hadron helicity conservation. Thus, we show that the scaling behavior observed in the d(γ,p)ncross sections is not a result of perturbative QCD. These data should provide important tests of new nonperturbative calculations in the intermediate energy regime.
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| 2. |
- Karlgren, Daniel, et al.
(författare)
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High-angular-momentum structures in Zn-64
- 2004
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 69, s. 1-034330
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Tidskriftsartikel (refereegranskat)abstract
- High-angular-momentum states in Zn-64 were populated in the Ca-40(Si-28,4p) reaction at a beam energy of 122 MeV. Evaporated, light, charged particles were identified by the Microball, while gamma rays were detected using the Gammasphere array. The main focus of this paper is on two strongly coupled, collective bands. The yrast band, which was previously known, has been linked to lower-lying states establishing the excitation energies and angular momenta of in-band states for the first time. The newly identified excited band decays to the yrast band but firm angular-momentum assignments could not be made. In order to interpret these structures cranked-Nilsson-Strutinsky calculations have been performed. The calculations have been extended to account for the distribution of nucleons within a configuration. The yrast collective band is interpreted as based on the pi(f(7/2))(-1)(p(3/2)f(5/2))(2)(g(9/2))(1)nu(p(3/2)f(5/2))(4)(g(9/2))(2) configuration. There are several possible interpretations of the second band but it is difficult to distinguish between the different possibilities.
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| 3. |
- Schulte, EC, et al.
(författare)
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High energy angular distribution measurements of the exclusive deuteron photodisintegration reaction
- 2002
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Ingår i: Physical Review C (Nuclear Physics). - : American Physical Society. - 0556-2813 .- 1089-490X. ; 66:4
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Tidskriftsartikel (refereegranskat)abstract
- The first complete measurements of the angular distributions of the two-body deuteron photodisintegration differential cross section at photon energies above 1.6 GeV were performed at the Thomas Jefferson National Accelerator Facility. The results show a persistent forward-backward asymmetry up to E-gamma=2.4 GeV, the highest-energy measured in this experiment. The Hard Rescattering and the Quark-Gluon string models are in fair agreement with the results.
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| 4. |
- Bäck, Torbjörn, et al.
(författare)
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First observation of gamma-rays from the proton emitter Au-171
- 2003
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 16:4, s. 489-494
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Tidskriftsartikel (refereegranskat)abstract
- Gamma-rays from the alpha- and proton-unstable nuclide Au-171 have been observed for the first time. The gamma-rays were correlated with both a proton- and an alpha-particle decay branch, confirming that the nucleus decays by alpha and proton emission from a single (11/2(-)) state. The measurement confirms the previously determined half-lives for these particle decays but the present values are of higher precision. In addition, a longer half-life than determined in previous work was measured for the proton-unstable tentative ground state. The results are discussed in relation to structures in neighbouring nuclei and compared with a Strutinsky-type TRS calculation.
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| 5. |
- da Silva, Giovanna M, et al.
(författare)
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The efficacy of a nerve stimulator (CaverMap) to enhance autonomic nerve identification and confirm nerve preservation during total mesorectal excision.
- 2004
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Ingår i: Diseases of the colon and rectum. - : Ovid Technologies (Wolters Kluwer Health). - 0012-3706. ; 47:12, s. 2032-8
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Sexual dysfunction after total mesorectal excision may be caused by injury to the autonomic nerves. During surgery, nerve identification is not always achieved, and, to date, there has been no method to objectively confirm nerve preservation. The aim of this study was to assess the efficacy of a nerve-stimulating device (CaverMap) to assist in the intraoperative identification of the autonomic nerves during total mesorectal excision, and objectively confirm nerve preservation after proctectomy is completed. PATIENTS AND METHODS: Sexually active consecutive male patients undergoing total mesorectal excision were prospectively enrolled in this study. During pelvic dissection, the surgeon attempted to localize the hypogastric and cavernous nerves. CaverMap was used to confirm these findings and to facilitate the identification in cases of uncertainty. At the completion of proctectomy, the nerves were restimulated to ensure preservation. Factors that could affect the surgeon's ability to localize the nerves and CaverMap to confirm this were evaluated. RESULTS: Twenty-nine male patients with a median age of 58 years were enrolled in this study. An attempt to visualize the hypogastric nerves during dissection was made in 26 patients; the surgeon was able to identify the nerves in 19 (73 percent) patients. CaverMap successfully identified the nerves in six of the seven remaining patients, and failed to identify them in only one case. An attempt to localize the cavernous nerves during dissection was made in 13 patients, of which localization was successful in 8 (61.5 percent) patients. CaverMap improved the identification rate in four of the remaining five patients. After proctectomy, CaverMap successfully confirmed the preservation of both hypogastric and cavernous nerves in 27 of 29 (93 percent) patients. A history of previous surgery statistically correlated with failure to identify the hypogastric nerves by the surgeon (P = 0.005). There were no adverse events related to use of the device. CONCLUSION: CaverMap may be a useful tool to facilitate identification of the pelvic autonomic nerves during total mesorectal excision and to objectively confirm nerve preservation.
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| 6. |
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| 7. |
- Molin, Daniël G M, et al.
(författare)
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Disturbed morphogenesis of cardiac outflow tract and increased rate of aortic arch anomalies in the offspring of diabetic rats
- 2004
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Ingår i: Birth Defects Research. Part A. Clinical and Molecular Teratology. - 1542-0752. ; 70:12, s. 927-938
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Maternal diabetes (MD) is a risk factor for offspring to develop cardiovascular anomalies; this is of growing clinical concern since the number of women in childbearing age with compromised glucose homeostasis is increasing. Hyperglycemia abrogates cardiovascular development in vitro; however, a link to cardiovascular defects in diabetic offspring remains to be investigated. METHODS: We have studied cardiovascular development in offspring of MD rats by examining serial histological sections of GD 12.0-18.0 offspring. Development of pharyngeal arch artery malformations was analyzed and related to intracardiac anomalies. RESULTS: Pharyngeal arch artery and intracardiac defects were present in 27 of 37 MD GD 13.0-18.0 offspring. Early sixth arch arteries showed abrogated arteriogenesis, whereas fourth arch artery defects developed as a result of abnormal remodeling. Morphometrical analysis showed increased apoptosis in regressing artery segments and reduced apoptosis in persisting artery segments. Double outlet right ventricle with infundibular stenosis (tetralogy of Fallot) was predominantly found in combination with sixth artery defects and pulmonary atresia. As confirmed by morphometric analysis and three-dimensional (3D)-reconstructions, outflow tract defects coincided with endocardial cushion hypoplasia. Cases with teratology of Fallot additionally showed a shorter outflow tract. No relation with apoptosis or disturbed neural crest cell migration was found. CONCLUSIONS: Our data uniquely demonstrate mechanistic differences involved in the development of sixth and fourth artery anomalies. Whereas increased apoptosis induces fourth artery anomalies, pulmonary outflow obstruction abrogates sixth artery differentiation independent of apoptosis. The model presented allows analysis of diabetic conditions on cardiovascular development in vivo, essential for elucidating this teratology.
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| 8. |
- Peres, N. M. R., et al.
(författare)
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Phase diagram and magnetic collective excitations of the Hubbard model for graphene sheets and layers
- 2004
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 70:19, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- We discuss the magnetic phases of the Hubbard model for the honeycomb lattice both in two and three spatial dimensions. A ground state phase diagram is obtained depending on the interaction strength U and electronic density n. We find a first order phase transition between ferromagnetic regions where the spin is maximally polarized (Nagaoka ferromagnetism) and regions with smaller magnetization (weak ferromagnetism). When taking into account the possibility of spiral states, we find that the lowest critical U is obtained for an ordering momentum different from zero. The evolution of the ordering momentum with doping is discussed. The magnetic excitations (spin waves) in the antiferromagnetic insulating phase are calculated from the random-phase approximation for the spin susceptibility. We also compute the spin fluctuation correction to the mean field magnetization by virtual emission/absorption of spin waves. In the large U limit, the renormalized magnetization agrees qualitatively with the Holstein-Primakoff theory of the Heisenberg antiferromagnet, although the latter approach produces a larger renormalization.
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| 9. |
- Singh, I N, et al.
(författare)
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Dynorphin A (1-17) induces apoptosis in striatal neurons in vitro through alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate/kainate receptor-mediated cytochrome c release and caspase-3 activation.
- 2003
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Ingår i: Neuroscience. - : Elsevier BV. - 0306-4522 .- 1873-7544. ; 122:4
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Tidskriftsartikel (refereegranskat)abstract
- Dynorphin A (1-17), an endogenous opioid neuropeptide, can have pathophysiological consequences at high concentrations through actions involving glutamate receptors. Despite evidence of excitotoxicity, the basic mechanisms underlying dynorphin-induced cell death have not been explored. To address this question, we examined the role of caspase-dependent apoptotic events in mediating dynorphin A (1-17) toxicity in embryonic mouse striatal neuron cultures. In addition, the role of opioid and/or glutamate receptors were assessed pharmacologically using dizocilpine maleate (MK(+)801), a non-equilibrium N-methyl-D-aspartate (NMDA) antagonist; 6-cyano-7-nitroquinoxaline-2,3-dione, a competitive alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)/kainate antagonist; or (-)-naloxone, a general opioid antagonist. The results show that dynorphin A (1-17) (>or=10 nM) caused concentration-dependent increases in caspase-3 activity that were accompanied by mitochondrial release of cytochrome c and the subsequent death of cultured mouse striatal neurons. Moreover, dynorphin A-induced neurotoxicity and caspase-3 activation were significantly attenuated by the cell permeable caspase inhibitor, caspase-3 inhibitor-II (z-DEVD-FMK), further suggesting an apoptotic cascade involving caspase-3. AMPA/kainate receptor blockade significantly attenuated dynorphin A-induced cytochrome c release and/or caspase-3 activity, while NMDA or opioid receptor blockade typically failed to prevent the apoptotic response. Last, dynorphin-induced caspase-3 activation was mimicked by the ampakine CX546 [1-(1,4-benzodioxan-6-ylcarbonyl)piperidine], which suggests that the activation of AMPA receptor subunits may be sufficient to mediate toxicity in striatal neurons. These findings provide novel evidence that dynorphin-induced striatal neurotoxicity is mediated by a caspase-dependent apoptotic mechanism that largely involves AMPA/kainate receptors.
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| 10. |
- Van de Vel, K., et al.
(författare)
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Fine structure in the alpha decay of Po-188,Po-192
- 2003
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 68:5
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Tidskriftsartikel (refereegranskat)abstract
- The alpha decay of Po-188,Po-192 has been reexamined in order to probe the 0(+) states in the daughter nuclei Pb-184,Pb-188 that can be associated with coexisting spherical, oblate, and/or prolate configurations. Improved values were measured for the excitation energy and the feeding alpha -decay intensity of the 0(2)(+) state in Pb-184,Pb-188 and conflicting results on the 0(3)(+) state in Pb-188 were clarified. All known cases of fine structure in the alpha decay of the even-even Po nuclei are reviewed. The reduced alpha-decay width systematics combined with potential-energy-surface calculations confirm the onset of deformation in the ground state of the polonium nuclei around the neutron midshell. An isomeric state with a half-life of 580(100)ns has been identified in Po-192 .
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