Exotic magnetism in the alkali sesquoxides Rb4O6 and Cs4O6

Among the various alkali oxides the sesquioxides Rb4O6 and Cs4O6 are of special interest. Electronic structure calculations using the local spin-density approximation predicted that Rb4O6 should be a half-metallic ferromagnet, which was later contradicted when an experimental investigation of the temperature dependent magnetization of Rb4O6 showed a low-temperature magnetic transition and differences between zero-field-cooled (ZFC) and field-cooled (FC) measurements. Such behavior is known from spin glasses and frustrated systems. Rb4O6 and Cs4O6 comprise two different types of dioxygen anions, the hyperoxide and the peroxide anions. The nonmagnetic peroxide anions do not contain unpaired electrons while the hyperoxide anions contain unpaired electrons in antibonding pi*-orbitals. High electron localization (narrow bands) suggests that electronic correlations are of major importance in these open shell p-electron systems. Correlations and charge ordering due to the mixed valency render p-electron-based anionogenic magnetic order possible in the sesquioxides. In this work we present an experimental comparison of Rb4O6 and the related Cs4O6. The crystal structures are verified using powder x-ray diffraction. The mixed valency of both compounds is confirmed using Raman spectroscopy, and time-dependent magnetization experiments indicate that both compounds show magnetic frustration, a feature only previously known from d- and f-electron systems

Evidence for Adiabatic Magnetization of cold Dy_N Clusters

Magnetic properties of Dy_N clusters in a molecular beam generated with a liquid helium cooled nozzle are investigated by Stern-Gerlach experiments. The cluster magnetizations \mu_z are measured as a function of magnetic field (B = 0 - 1.6T) and cluster size (16 < N < 56). The most important observation is the saturation of the magnetization \mu_z(B) at large field strengths. The magnetization approaches saturation following the power law |\mu_z-\mu_0| proportional to 1/\sqrt{B}, where \mu_0 denotes the magnetic moment. This gives evidence for adiabatic magnetization.Comment: 4 pages, 3 figure

Workload measurement in a communication application operated through a P300-based brain-computer interface

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Derivation of induced pluripotent stem cells (iPSCs) by retroviral transduction of skin fibroblasts from four patients suffering 7q11.23 microduplication syndrome

Skin fibroblasts were obtained from four patients with 7q11.23 microduplication syndrome carrying the reciprocal rearrangement of Williams-Beuren syndrome at the 7q11.23 genomic region. Induced pluripotent stem cells (iPSCs) were generated by retroviral infection of fibroblasts with polycystronic vectors. The generated iPSC clones ESi058B, ESi057B, ESi070A and ESi071A had the 7q11.23 duplication with no additional genomic alterations, a stable karyotype, expressed pluripotency markers and could differentiate towards the three germ layers in vitro via embryoid body formation and in vivo by teratoma formation. Patient's derived iPSCs are a valuable resource for in vitro modeling of 7q11.23 microduplication syndrome

Proof-of-Principle of a Brain-Computer Interface approach to support post-stroke arm rehabilitation in hospitalized patients: design, acceptability and usability

Objective To evaluate the feasibility of brain-computer interface (BCI)-assisted motor imagery training to support hand/arm motor rehabilitation after stroke during hospitalization. Design Proof-of-principle study. Setting Neurorehabilitation hospital. Participants Convenience sample of patients (N=8) with new-onset arm plegia or paresis caused by unilateral stroke. Interventions The BCI-based intervention was administered as an "add-on" to usual care and lasted 4 weeks. Under the supervision of a therapist, patients were asked to practice motor imagery of their affected hand and received as a discrete feedback the movements of a "virtual" hand superimposed on their own. Such a BCI-based device was installed in a rehabilitation hospital ward. Main Outcome Measures Following a user-centered design, we assessed system usability in terms of motivation, satisfaction (by means of visual analog scales), and workload (National Aeronautics and Space Administration-Task Load Index). The usability of the BCI-based system was also evaluated by 15 therapists who participated in a focus group. Results All patients successfully accomplished the BCI training. Significant positive correlations were found between satisfaction and motivation (P=.001, r=.393). BCI performance correlated with interest (P=.027, r=.257) and motivation (P=.012, r=.289). During the focus group, professionals positively acknowledged the opportunity offered by BCI-assisted training to measure patients' adherence to rehabilitation. Conclusions An ecological BCI-based device to assist motor imagery practice was found to be feasible as an add-on intervention and tolerable by patients who were exposed to the system in the rehabilitation environment. © 2015 American Congress of Rehabilitation Medicine

¹¹ C radiolabeling of anle253b: A putative PET tracer for Parkinson's disease that binds to α-synuclein fibrils in vitro and crosses the blood-brain barrier.

There is an urgent clinical need for imaging of α-synuclein (αSyn) fibrils, the hallmark biomarker for Parkinson's disease, in neurodegenerative disorders. Despite immense efforts, promising tracer candidates for nuclear imaging of αSyn are rare. Diphenyl pyrazoles are known modulators of αSyn aggregation and thus bear potential for non-invasive detection of this biomarker in vivo. Here we demonstrate high-affinity binding of the family member anle253b to fibrillar αSyn and present a high-yielding site-selective radiosynthesis route for 11 C radiolabeling using in-situ generated [11 C]formaldehyde and reductive methylation. Radio-HPLC of the tracer after incubation with rat serum in vitro shows excellent stability of the molecule. Positron emission tomography in healthy animals is used to assess the pharmacokinetics and biodistribution of the tracer, showing good penetration of the blood-brain barrier and low background binding to the non-pathological brain

Concerted changes in tropical forest structure and dynamics: evidence from 50 South American long-term plots

Several widespread changes in the ecology of old-growth tropical forests have recently been documented for the late twentieth century, in particular an increase in stem turnover (pan-tropical), and an increase in above-ground biomass (neotropical). Whether these changes are synchronous and whether changes in growth are also occurring is not known. We analysed stand-level changes within 50 long-term. monitoring plots from across South America spanning 1971-2002. We show that: (i) basal area (BA: sum of the cross-sectional areas of all trees in a plot) increased significantly over time (by 0.10 +/- 0.04 m(2) ha(-1) yr(-1), mean +/- 95% CI); as did both (ii) stand-level BA growth rates (sum of the increments of BA of surviving trees and BA of new trees that recruited into a plot); and (iii) stand-level BA mortality rates (sum of the cross-sectional areas of all trees that died in a plot). Similar patterns were observed on a per-stem basis: (i) stem density (number of stems per hectare; 1 hectare is 10(4) m(2)) increased significantly over time (0.94 +/- 0.63 stems ha(-1) yr(-1)); as did both (ii) stem recruitment rates; and (iii) stem mortality rates. In relative terms, the pools of BA and stem density increased by 0.38 +/- 0.15% and 0.18 +/- 0.12% yr(-1), respectively. The fluxes into and out of these pools-stand-level BA growth, stand-level BA mortality, stem recruitment and stem mortality rates-increased, in relative terms, by an order of magnitude more. The gain terms (BA growth, stem recruitment) consistently exceeded the loss terms (BA loss, stem mortality) throughout the period, suggesting that whatever process is driving these changes was already acting before the plot network was established. Large long-term increases in stand-level BA growth and simultaneous increases in stand BA and stem density imply a continent-wide increase in resource availability which is increasing net primary productivity and altering forest dynamics. Continent-wide changes in incoming solar radiation, and increases in atmospheric concentrations of CO2 and air temperatures may have increased resource supply over recent decades, thus causing accelerated growth and increased dynamism across the world's largest tract of tropical forest

[11C]MODAG-001—towards a PET tracer targeting α-synuclein aggregates

Purpose Deposition of misfolded alpha-synuclein (αSYN) aggregates in the human brain is one of the major hallmarks of synucleinopathies. However, a target-specific tracer to detect pathological aggregates of αSYN remains lacking. Here, we report the development of a positron emission tomography (PET) tracer based on anle138b, a compound shown to have therapeutic activity in animal models of neurodegenerative diseases. Methods Specificity and selectivity of [3H]MODAG-001 were tested in in vitro binding assays using recombinant fibrils. After carbon-11 radiolabeling, the pharmacokinetic and metabolic profile was determined in mice. Specific binding was quantified in rats, inoculated with αSYN fibrils and using in vitro autoradiography in human brain sections of Lewy body dementia (LBD) cases provided by the Neurobiobank Munich (NBM). Results [3H]MODAG-001 revealed a very high affinity towards pure αSYN fibrils (Kd = 0.6 ± 0.1 nM) and only a moderate affinity to hTau46 fibrils (Kd = 19 ± 6.4 nM) as well as amyloid-β1–42 fibrils (Kd = 20 ± 10 nM). [11C]MODAG-001 showed an excellent ability to penetrate the mouse brain. Metabolic degradation was present, but the stability of the parent compound improved after selective deuteration of the precursor. (d3)-[11C]MODAG-001 binding was confirmed in fibril-inoculated rat striata using in vivo PET imaging. In vitro autoradiography showed no detectable binding to aggregated αSYN in human brain sections of LBD cases, most likely, because of the low abundance of aggregated αSYN against background protein. Conclusion MODAG-001 provides a promising lead structure for future compound development as it combines a high affinity and good selectivity in fibril-binding assays with suitable pharmacokinetics and biodistribution properties