Reversals in nature and the nature of reversals

The asymmetric shape of reversals of the Earth's magnetic field indicates a possible connection with relaxation oscillations as they were early discussed by van der Pol. A simple mean-field dynamo model with a spherically symmetric $\alpha$ coefficient is analysed with view on this similarity, and a comparison of the time series and the phase space trajectories with those of paleomagnetic measurements is carried out. For highly supercritical dynamos a very good agreement with the data is achieved. Deviations of numerical reversal sequences from Poisson statistics are analysed and compared with paleomagnetic data. The role of the inner core is discussed in a spectral theoretical context and arguments and numerical evidence is compiled that the growth of the inner core might be important for the long term changes of the reversal rate and the occurrence of superchrons.Comment: 24 pages, 12 figure

Impact of supporting people with advanced Parkinson’s disease on carer’s quality of life and burden

Purpose: The aim of this study was to assess the burden and the quality of life (QoL) perceived by caregivers assisting advanced Parkinson’s disease (PD) patients. Patients and Methods: Consecutive advanced PD patients treated with levodopa/carbidopa intestinal gel (LCIG) or continuous subcutaneous apomorphine infusion (CSAI) or care as usual (CU) and their care partners were recruited during routine visits according to a cross-sectional design. Caregiver’s distress was assessed by Zarit Burden Interview (ZBI) and a QoL survey to evaluate and understand the burden experienced by care partners during family and working activities. Results: A total of 126 patients (53 LCIG, 19 CSAI and 54 CU) and their care partners were enrolled. The ZBI score boxplot showed that LCIG and CU populations have a similar distribution (ZBI inter-quartile range [IQR] values respectively 18–42 for LCIG and 19–43 for CU group), while the CSAI group has a wider score range (IQR 16–52). Caregivers assisting patients in treatment with LCIG have more time to perform family or household duties (p=0.0022), or to engage in leisure activities (p=0.0073) compared to CU, while no difference was found when compared to CSAI group. Approximately 50% of the care partners showed mood changes in the last 6 months and LCIG and CSAI had less impact on caregiver’s mood compared to CU. Patients treated with LCIG were more independent in taking a bath or shower without assistance and were more able to move and walk without assistance. Conclusion: Care partners of advanced PD patients treated with device-aided therapies have more time for their own life and a better perception of their QoL with a tendency to an improvement of mood compared with those of patients treated with CU

Distribution of the daily Sunspot Number variation for the last 14 solar cycles

The difference between consecutive daily Sunspot Numbers was analysed. Its distribution was approximated on a large time scale with an exponential law. In order to verify this approximation a Maximum Entropy distribution was generated by a modified version of the Simulated Annealing algorithm. The exponential approximation holds for the generated distribution too. The exponential law is characteristic for time scales covering whole cycles and it is mostly a characteristic of the Sunspot Number fluctuations and not of its average variation.Comment: Accepted for publication in Solar Physic

Endogenous cholinergic inputs and local circuit mechanisms govern the phasic mesolimbic dopamine response to nicotine

Nicotine exerts its reinforcing action by stimulating nicotinic acetylcholine receptors (nAChRs) and boosting dopamine (DA) output from the ventral tegmental area (VTA). Recent data have led to a debate about the principal pathway of nicotine action: direct stimulation of the DAergic cells through nAChR activation, or disinhibition mediated through desensitization of nAChRs on GABAergic interneurons. We use a computational model of the VTA circuitry and nAChR function to shed light on this issue. Our model illustrates that the α4β2-containing nAChRs either on DA or GABA cells can mediate the acute effects of nicotine. We account for in vitro as well as in vivo data, and predict the conditions necessary for either direct stimulation or disinhibition to be at the origin of DA activity increases. We propose key experiments to disentangle the contribution of both mechanisms. We show that the rate of endogenous acetylcholine input crucially determines the evoked DA response for both mechanisms. Together our results delineate the mechanisms by which the VTA mediates the acute rewarding properties of nicotine and suggest an acetylcholine dependence hypothesis for nicotine reinforcement.Peer reviewe

Design and Beam Test Results for the sPHENIX Electromagnetic and Hadronic Calorimeter Prototypes

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Prolonged oral cannabinoid administration prevents neuroinflammation, lowers β-amyloid levels and improves cognitive performance in Tg APP 2576 mice

Background: Alzheimer’s disease (AD) brain shows an ongoing inflammatory condition and non-steroidal antiinflammatories diminish the risk of suffering the neurologic disease. Cannabinoids are neuroprotective and antiinflammatory agents with therapeutic potential. Methods: We have studied the effects of prolonged oral administration of transgenic amyloid precursor protein (APP) mice with two pharmacologically different cannabinoids (WIN 55,212-2 and JWH-133, 0.2 mg/kg/day in the drinking water during 4 months) on inflammatory and cognitive parameters, and on 18F-fluoro-deoxyglucose (18FDG) uptake by positron emission tomography (PET). Results: Novel object recognition was significantly reduced in 11 month old Tg APP mice and 4 month administration of JWH was able to normalize this cognitive deficit, although WIN was ineffective. Wild type mice cognitive performance was unaltered by cannabinoid administration. Tg APP mice showed decreased 18FDG uptake in hippocampus and cortical regions, which was counteracted by oral JWH treatment. Hippocampal GFAP immunoreactivity and cortical protein expression was unaffected by genotype or treatment. In contrast, the density of Iba1 positive microglia was increased in Tg APP mice, and normalized following JWH chronic treatment. Both cannabinoids were effective at reducing the enhancement of COX-2 protein levels and TNF-a mRNA expression found in the AD model. Increased cortical b-amyloid (Ab) levels were significantly reduced in the mouse model by both cannabinoids. Noteworthy both cannabinoids enhanced Ab transport across choroid plexus cells in vitro. Conclusions: In summary we have shown that chronically administered cannabinoid showed marked beneficial effects concomitant with inflammation reduction and increased Ab clearanceThis work was supported by the Spanish Ministry of Science and Technology (SAF 2005-02845 to M.L.C). A.M.M-M. was recipient a fellowship from the Ministry of Education and Scienc

Nicotinic Receptors Underlying Nicotine Dependence: Evidence from Transgenic Mouse Models.

Nicotine underlies the reinforcing properties of tobacco cigarettes and e-cigarettes. After inhalation and absorption, nicotine binds to various nicotinic acetylcholine receptor (nAChR) subtypes localized on the pre- and postsynaptic membranes of cells, which subsequently leads to the modulation of cellular function and neurotransmitter signaling. In this chapter, we begin by briefly reviewing the current understanding of nicotine's actions on nAChRs and highlight considerations regarding nAChR subtype localization and pharmacodynamics. Thereafter, we discuss the seminal discoveries derived from genetically modified mouse models, which have greatly contributed to our understanding of nicotine's effects on the reward-related mesolimbic pathway and the aversion-related habenulo-interpeduncular pathway. Thereafter, emerging areas of research focusing on modulation of nAChR expression and/or function are considered. Taken together, these discoveries have provided a foundational understanding of various genetic, neurobiological, and behavioral factors underlying the motivation to use nicotine and related dependence processes, which are thereby advancing drug discovery efforts to promote long-term abstinence

Adolescent Brain Development and the Risk for Alcohol and Other Drug Problems

Dynamic changes in neurochemistry, fiber architecture, and tissue composition occur in the adolescent brain. The course of these maturational processes is being charted with greater specificity, owing to advances in neuroimaging and indicate grey matter volume reductions and protracted development of white matter in regions known to support complex cognition and behavior. Though fronto-subcortical circuitry development is notable during adolescence, asynchronous maturation of prefrontal and limbic systems may render youth more vulnerable to risky behaviors such as substance use. Indeed, binge-pattern alcohol consumption and comorbid marijuana use are common among adolescents, and are associated with neural consequences. This review summarizes the unique characteristics of adolescent brain development, particularly aspects that predispose individuals to reward seeking and risky choices during this phase of life, and discusses the influence of substance use on neuromaturation. Together, findings in this arena underscore the importance of refined research and programming efforts in adolescent health and interventional needs