The high-energy hadron spin-flip amplitude at small momentum transfer and new AN data from RHIC

In the case of elastic high-energy hadron-hadron scattering, the impact of the large-distance contributions on the behaviour of the slopes of the spin-non-flip and of the spin-flip amplitudes is analysed. It is shown that the long tail of the hadronic potential in impact parameter space leads to a value of the slope of the reduced spin-flip amplitude larger than that of the spin-non-flip amplitude. This effect is taken into account in the calculation of the analysing power in proton-nucleus reactions at high energies. It is shown that the preliminary measurement of AN obtained by the E950 Collaboration indeed favour a spin-flip-amplitude with a large slope. Predictions for AN at pL = 250 GeV/c are given.Comment: 16 pages, 5 figures, a few typos fixed in v.

Is there exist a hadron spin-flip contribution in the Coulomb-hadron interference at small transfer momenta and high energies

The analysing power $A_N$ is examined in the range of the Coulomb-hadron interferenceon on the basis of the experimental data from p_L = 6 GeV/c up to 200 GeV/c taking account of a phenomenological analysis at p_L = 6 GeV/c and a dynamic high-energy spin model. The results are compared with the new RHIC data at p_L = 100 GeV/c. The new experimental data obtained at RHIC indicate the small contributions of the hadrons spin-flip amplitude.Comment: 18 pages, 8 figures, Table Essentially revision. Figures and Table are added, fit with new final data are made. Conclusion is not chang

Functional Integration of Grafted Neural Stem Cell-Derived Dopaminergic Neurons Monitored by Optogenetics in an In Vitro Parkinson Model

Intrastriatal grafts of stem cell-derived dopamine (DA) neurons induce behavioral recovery in animal models of Parkinson's disease (PD), but how they functionally integrate in host neural circuitries is poorly understood. Here, Wnt5a-overexpressing neural stem cells derived from embryonic ventral mesencephalon of tyrosine hydroxylase-GFP transgenic mice were expanded as neurospheres and transplanted into organotypic cultures of wild type mouse striatum. Differentiated GFP-labeled DA neurons in the grafts exhibited mature neuronal properties, including spontaneous firing of action potentials, presence of post-synaptic currents, and functional expression of DA D2 autoreceptors. These properties resembled those recorded from identical cells in acute slices of intrastriatal grafts in the 6-hydroxy-DA-induced mouse PD model and from DA neurons in intact substantia nigra. Optogenetic activation or inhibition of grafted cells and host neurons using channelrhodopsin-2 (ChR2) and halorhodopsin (NpHR), respectively, revealed complex, bi-directional synaptic interactions between grafted cells and host neurons and extensive synaptic connectivity within the graft. Our data demonstrate for the first time using optogenetics that ectopically grafted stem cell-derived DA neurons become functionally integrated in the DA-denervated striatum. Further optogenetic dissection of the synaptic wiring between grafted and host neurons will be crucial to clarify the cellular and synaptic mechanisms underlying behavioral recovery as well as adverse effects following stem cell-based DA cell replacement strategies in PD

Evidence of Dopaminergic Processing of Executive Inhibition

Inhibition of unwanted response is an important function of the executive system. Since the inhibitory system is impaired in patients with dysregulated dopamine system, we examined dopamine neurotransmission in the human brain during processing of a task of executive inhibition. The experiment used a recently developed dynamic molecular imaging technique to detect and map dopamine released during performance of a modified Eriksen's flanker task. In this study, young healthy volunteers received an intravenous injection of a dopamine receptor ligand (11C-raclopride) after they were positioned in the PET camera. After the injection, volunteers performed the flanker task under Congruent and Incongruent conditions in a single scan session. They were required to inhibit competing options to select an appropriate response in the Incongruent but not in the Congruent condition. The PET data were dynamically acquired during the experiment and analyzed using two variants of the simplified reference region model. The analysis included estimation of a number of receptor kinetic parameters before and after initiation of the Incongruent condition. We found increase in the rate of ligand displacement (from receptor sites) and decrease in the ligand binding potential in the Incongruent condition, suggesting dopamine release during task performance. These changes were observed in small areas of the putamen and caudate bilaterally but were most significant on the dorsal aspect of the body of left caudate. The results provide evidence of dopaminergic processing of executive inhibition and demonstrate that neurochemical changes associated with cognitive processing can be detected and mapped in a single scan session using dynamic molecular imaging

Changes in Striatal Dopamine Release Associated with Human Motor-Skill Acquisition

The acquisition of new motor skills is essential throughout daily life and involves the processes of learning new motor sequence and encoding elementary aspects of new movement. Although previous animal studies have suggested a functional importance for striatal dopamine release in the learning of new motor sequence, its role in encoding elementary aspects of new movement has not yet been investigated. To elucidate this, we investigated changes in striatal dopamine levels during initial skill-training (Day 1) compared with acquired conditions (Day 2) using 11C-raclopride positron-emission tomography. Ten volunteers learned to perform brisk contractions using their non-dominant left thumbs with the aid of visual feedback. On Day 1, the mean acceleration of each session was improved through repeated training sessions until performance neared asymptotic levels, while improved motor performance was retained from the beginning on Day 2. The 11C-raclopride binding potential (BP) in the right putamen was reduced during initial skill-training compared with under acquired conditions. Moreover, voxel-wise analysis revealed that 11C-raclopride BP was particularly reduced in the right antero-dorsal to the lateral part of the putamen. Based on findings from previous fMRI studies that show a gradual shift of activation within the striatum during the initial processing of motor learning, striatal dopamine may play a role in the dynamic cortico-striatal activation during encoding of new motor memory in skill acquisition

A Functional Genomic Screen Combined with Time-Lapse Microscopy Uncovers a Novel Set of Genes Involved in Dorsal Closure of Drosophila Embryos

Morphogenesis, the establishment of the animal body, requires the coordinated rearrangement of cells and tissues regulated by a very strictly-determined genetic program. Dorsal closure of the epithelium in the Drosophila melanogaster embryo is one of the best models for such a complex morphogenetic event. To explore the genetic regulation of dorsal closure, we carried out a large-scale RNA interference-based screen in combination with in vivo time-lapse microscopy and identified several genes essential for the closure or affecting its dynamics. One of the novel dorsal closure genes, the small GTPase activator pebble (pbl), was selected for detailed analysis. We show that pbl regulates actin accumulation and protrusion dynamics in the leading edge of the migrating epithelial cells. In addition, pbl affects dorsal closure dynamics by regulating head involution, a morphogenetic process mechanically coupled with dorsal closure. Finally, we provide evidence that pbl is involved in closure of the adult thorax, suggesting its general requirement in epithelial closure processes

β1 Integrin Maintains Integrity of the Embryonic Neocortical Stem Cell Niche

IInteractions between laminins and integrin receptors hold neural stem cells in place at the ventricular surface of embryonic brain. Transient disruption leads to abnormal stem cell divisions and permanent cortical malformation

A Novel Role for Dbx1-Derived Cajal-Retzius Cells in Early Regionalization of the Cerebral Cortical Neuroepithelium

Patterning of the cerebral cortex during embryogenesis depends not only on passive diffusion of morphogens but also on signal delivery by Cajal-Retzius neurons that migrate over long distances

Boreal forest soil carbon fluxes one year after a wildfire: Effects of burn severity and management

The extreme 2018 hot drought that affected central and northern Europe led to the worst wildfire season in Sweden in over a century. The Ljusdal fire complex, the largest area burnt that year (8995 ha), offered a rare opportunity to quantify the combined impacts of wildfire and post-fire management on Scandinavian boreal forests. We present chamber measurements of soil CO2 and CH4 fluxes, soil microclimate and nutrient content from five Pinus sylvestris sites for the first growing season after the fire. We analysed the effects of three factors on forest soils: burn severity, salvage-logging and stand age. None of these caused significant differences in soil CH4 uptake. Soil respiration, however, declined significantly after a high-severity fire (complete tree mortality) but not after a low-severity fire (no tree mortality), despite substantial losses of the organic layer. Tree root respiration is thus key in determining post-fire soil CO2 emissions and may benefit, along with heterotrophic respiration, from the nutrient pulse after a low-severity fire. Salvage-logging after a high-severity fire had no significant effects on soil carbon fluxes, microclimate or nutrient content compared with leaving the dead trees standing, although differences are expected to emerge in the long term. In contrast, the impact of stand age was substantial: a young burnt stand experienced more extreme microclimate, lower soil nutrient supply and significantly lower soil respiration than a mature burnt stand, due to a thinner organic layer and the decade-long effects of a previous clear-cut and soil scarification. Disturbance history and burn severity are, therefore, important factors for predicting changes in the boreal forest carbon sink after wildfires. The presented short-term effects and ongoing monitoring will provide essential information for sustainable management strategies in response to the increasing risk of wildfire