Production cross sections of residual nuclei obtained by knockout and fragmentation reactions of different tin isotopes accelerated at 1A GeV have been measured with the fragment separator (FRS) at ...GSI, Darmstadt. The new measurements are used to investigate the neutron-excess dependence of the neutron- and proton-knockout cross sections. These cross sections are compared toGlauber model calculations coupled to a nuclear de-excitation code in order to investigate the role of the remnant excitations. This bench marking shows an overestimation of the cross sections for the removal of deeply bound nucleons. A phenomenological increase in the excitation energy induced in the remnants produced in these cases allows us to reproduce the measured cross sections.
In a high-energy fragmentation experiment at GSI an I=π(6+) isomer and its γ-decay are identified in 102Sn, the two-neutron neighbour of the doubly-magic 100Sn. Its half-life is measured to be ...T=1/2367(11) ns. The possible existence of further isomers is discussed in the framework of large-scale shell model (LSSM) calculations including up to five particle-hole excitations of the 100Sn core. From the precise B(E2; 6+→4+) strength and the recently remeasured value for B(E2; 8+→6+) in the two-proton hole neighbour 98Cd effective E2 polarization charges for protons and neutrons were inferred including LSSM corrections within the full N=4 0ħω space. The results are discussed in comparison to predicted and empirically determined effective operators.
Background: Although mast cells are known to secrete a broad spectrum of proinflammatory and immunomodulatory cytokines, the role of these molecules in mast cell–dependent cutaneous inflammation is ...not clear.
Objective: We decided to study biopsy specimens from lesional and nonlesional skin of patients with acute, chronic recurrent, delayed pressure, and cold urticaria; from fleeting wheals of prick test reactions to allergens; and from normal skin of nonallergic subjects.
Methods: Cryostat sections were stained by immunohistochemistry with antibodies against IL-3, IL-8, TNF-α, and mast cell–specific tryptase. In serial sections with tryptase and each cytokine, reactivity of mast cells was studied as well.
Results: Compared with normal skin and prick test reactions, immunoreactivity for TNF-α and IL-3 was significantly increased on endothelial and perivascular cells of the upper dermis in all urticaria lesions. In nonlesional skin comparable upregulation was noted on endothelial cells and for TNF-α on perivascular cells of patients with delayed pressure urticaria. In addition, TNF-α was expressed throughout the epidermis in lesional and nonlesional skin of patients with all types of urticaria, but not in normal control subjects. Sequential biopsy specimens from patients with cold urticaria showed upregulation of TNF-α and IL-3 on endothelial cells 30 minutes after elicitation of lesions with an ice cube. In contrast to these findings, epidermal immunoreactivity, as well as endothelial and perivascular cell expression of IL-8, were only slightly altered in urticaria compared with normal skin. In sequentially stained sections, few tryptase-positive mast cells reacted to TNF-α, few reacted to IL-3 in pressure urticaria only, and practically none stained for IL-8.
Conclusion: These findings suggest that the cytokines studied here are involved in the pathology of urticaria, possibly by inducing subthreshold inflammation in endothelial cells of uninvolved skin. (J Allergy Clin Immunol 1999;103:307-14.)
Absolute differential cross sections for elastic p7Be and p8B small-angle scattering were measured in inverse kinematics at an energy of 0.7 GeV/u at GSI Darmstadt. The hydrogen-filled ionization ...chamber IKAR was used as an active target to detect the recoil protons. The projectile tracking and isotope identification were performed with multi-wire proportional chambers and scintillation detectors. The measured cross sections were analysed using the Glauber multiple-scattering theory. The root-mean-square (rms) nuclear matter radii Rm=2.42(4) fm for 7Be and Rm=2.58(6) fm for 8B were obtained. The radial density distribution deduced for 8B exhibits a proton halo structure with the rms halo radius Rh=4.24(25) fm. A comparison of the deduced experimental radii is displayed with existing experimental and theoretical data.
Low energy fission of 234,235,236,238U and 237,238Np radioactive beams, provided by the GSI/FRS facility, has been studied using the R3B/SOFIA setup. The latter allows, on an event-by-event basis, to ...simultaneously identify, in terms of their mass and atomic numbers, the fissioning nucleus in coincidence with both fission fragments after prompt-neutron emission. This presentation reports on new results on elemental, isobaric and isotopic yields.
As is known, Alzheimer’s disease (AD) is associated with cognitive deficits due to significant neuronal loss. Reduced connectivity might be manifested as changes in the synchronization of electrical ...activity of collaborating parts of the brain. We used wavelet coherence to estimate linear/nonlinear synchronization between EEG samples recorded from different leads. Mutual information was applied to the complex wavelet coefficients in wavelet scales to estimate nonlinear synchronization. Synchronization rates for a group of 110 patients with moderate AD (MMSE score 10 to 19) and a group of 110 healthy control subjects were compared. The most significant decrease in mutual information in AD patients was observed on the third scale in the fronto-temporal area and for wavelet coherence within the same areas as for mutual information; these areas are preferentially affected by atrophy in AD. The new method used utilizes mutual information in wavelet scales and demonstrates larger discriminatory values in AD compared to wavelet coherence.
Muscle, cutaneous and joint afferents continuously signal information about the position and movement of individual joints.
How does the nervous system extract more global information, for example ...about the position of the foot in space? To study
this question we used microelectrode arrays to record impulses simultaneously from up to 100 discriminable nerve cells in
the L6 and L7 dorsal root ganglia (DRG) of the anaesthetized cat. When the hindlimb was displaced passively with a random
trajectory, the firing rate of the neurones could be predicted from a linear sum of positions and velocities in Cartesian
( x , y ), polar or joint angular coordinates. The process could also be reversed to predict the kinematics of the limb from the firing
rates of the neurones with an accuracy of 1â2 cm. Predictions of position and velocity could be combined to give an improved
fit to limb position. Decoders trained using random movements successfully predicted cyclic movements and movements in which
the limb was displaced from a central point to various positions in the periphery. A small number of highly informative neurones
(6â8) could account for over 80% of the variance in position and a similar result was obtained in a realistic limb model.
In conclusion, this work illustrates how populations of sensory receptors may encode a sense of limb position and how the
firing of even a small number of neurones can be used to decode the position of the limb in space.
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