133 research outputs found

    Higher serum vitamin D3 levels are associated with better cognitive test performance in patients with Alzheimer's disease

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    Background/Aims: Recent studies suggest that vitamin D metabolites may be important for preserving cognitive function via specific neuroprotective effects. No large studies have examined the association between vitamin D status and cognition. Methods: In this cross-sectional study, we analyzed the serum 25-hydroxyvitamin D3levels and Mini-Mental State Examination (MMSE) test scores of 225 older outpatients who were diagnosed as having probable Alzheimer's disease (AD). In addition to the 25-hydroxyvitamin D3levels, we analyzed the serum vitamin B1, B6and B12levels. Results: An association was found between MMSE test scores and serum 25-hydroxyvitamin D3levels, with a β-coefficient of 0.05 (p = 0.01). Vitamin-D-sufficient patients had significantly higher MMSE scores as compared to vitamin-D-insufficient ones. No association was found with the other serum vitamin levels. Conclusions: These data support the idea that a relationship exists between vitamin D status and cognition in patients with probable AD. However, given the cross-sectional design of this study, no causality can be concluded. Further prospective studies are needed to specify the contribution of vitamin D status to the onset and course of cognitive decline and AD. Copyrigh

    Large tunable valley splitting in edge-free graphene quantum dots on boron nitride

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    Coherent manipulation of binary degrees of freedom is at the heart of modern quantum technologies. Graphene offers two binary degrees: the electron spin and the valley. Efficient spin control has been demonstrated in many solid state systems, while exploitation of the valley has only recently been started, yet without control on the single electron level. Here, we show that van-der Waals stacking of graphene onto hexagonal boron nitride offers a natural platform for valley control. We use a graphene quantum dot induced by the tip of a scanning tunneling microscope and demonstrate valley splitting that is tunable from -5 to +10 meV (including valley inversion) by sub-10-nm displacements of the quantum dot position. This boosts the range of controlled valley splitting by about one order of magnitude. The tunable inversion of spin and valley states should enable coherent superposition of these degrees of freedom as a first step towards graphene-based qubits

    CMB-S4 Science Book, First Edition

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    This book lays out the scientific goals to be addressed by the next-generation ground-based cosmic microwave background experiment, CMB-S4, envisioned to consist of dedicated telescopes at the South Pole, the high Chilean Atacama plateau and possibly a northern hemisphere site, all equipped with new superconducting cameras. CMB-S4 will dramatically advance cosmological studies by crossing critical thresholds in the search for the B-mode polarization signature of primordial gravitational waves, in the determination of the number and masses of the neutrinos, in the search for evidence of new light relics, in constraining the nature of dark energy, and in testing general relativity on large scales

    Inexpensive protein overexpression driven by the NarL transcription activator protein

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    Most Escherichia coli overexpression vectors used for recombinant protein production (RPP) depend on organic inducers, for example, sugars or simple conjugates. However, these can be expensive and, sometimes, chemically unstable. To simplify this and to cut the cost of RPP, we have developed vectors controlled by the Escherichia coli nitrate-responsive NarL transcription activator protein, which use nitrate, a cheap, stable, and abundant inorganic ion, to induce high-level controlled RPP. We show that target proteins, such as green fluorescent protein, human growth hormone, and single-chain variable region antibody fragments can be expressed to high levels using our promoter systems. As nitrate levels are high in many commercial fertilizers, we demonstrate that controlled RPP can be achieved using readily available and inexpensive garden products

    Scientific Verification Of Faraday Rotation Modulators: Detection Of Diffuse Polarized Galactic Emission

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    The design and performance of a wide bandwidth linear polarization modulator based on the Faraday effect is described. Faraday Rotation Modulators (FRMs) are solid-state polarization switches that are capable of modulation up to 10 kHz. Six FRMs were utilized during the 2006 observing season in the Background Imaging of Cosmic Extragalactic Polarization (BICEP) experiment; three FRMs were used at each of BICEP's 100 and 150 GHz frequency bands. The technology was verified through high signal-to-noise detection of Galactic polarization using two of the six FRMs during four observing runs in 2006. The features exhibit strong agreement with BICEP's measurements of the Galaxy using non-FRM pixels and with the Galactic polarization models. This marks the first detection of high signal-to-noise mm-wave celestial polarization using fast, active optical modulation. The performance of the FRMs during periods when they were not modulated was also analyzed and compared to results from BICEP's 43 pixels without FRMs.Astronom

    Receiver development for BICEP Array, a next-generation CMB polarimeter at the South Pole

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    A detection of curl-type (B-mode) polarization of the primary CMB would be direct evidence for the inflationary paradigm of the origin of the Universe. The Bicep/Keck Array (BK) program targets the degree angular scales, where the power from primordial B-mode polarization is expected to peak, with ever-increasing sensitivity and has published the most stringent constraints on inflation to date. Bicep Array (BA) is the Stage-3 instrument of the BK program and will comprise four Bicep3-class receivers observing at 30/40, 95, 150 and 220/270 GHz with a combined 32,000+ detectors; such wide frequency coverage is necessary for control of the Galactic foregrounds, which also produce degree-scale B-mode signal. The 30/40 GHz receiver is designed to constrain the synchrotron foreground and has begun observing at the South Pole in early 2020. By the end of a 3-year observing campaign, the full Bicep Array instrument is projected to reach σr between 0.002 and 0.004, depending on foreground complexity and degree of removal of B-modes due to gravitational lensing (delensing). This paper presents an overview of the design, measured on-sky performance and calibration of the first BA receiver. We also give a preview of the added complexity in the time-domain multiplexed readout of the 7,776-detector 150 GHz receiver

    The Stubenberg meteorite—An LL6 chondrite fragmental breccia recovered soon after precise prediction of the strewn field

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    On March 6, 2016 at 21:36:51 UT, extended areas of Upper Austria, Bavaria (Germany) and the southwestern part of the Czech Republic were illuminated by a very bright bolide. This bolide was recorded by instruments in the Czech part of the European Fireball Network and it enabled complex and precise description of this event including prediction of the impact area. So far six meteorites totaling 1473 g have been found in the predicted area. The first pieces were recovered on March 12, 2016 on a field close to the village of Stubenberg (Bavaria). Stubenberg is a weakly shocked (S3) fragmental breccia consisting of abundant highly recrystallized rock fragments embedded in a clastic matrix. The texture, the large grain size of plagioclase, and the homogeneous compositions of olivine (Fa31.4) and pyroxene (Fs25.4) clearly indicate that Stubenberg is an LL6 chondrite breccia. This is consistent with the data on O, Ti, and Cr isotopes. Stubenberg does not contain solar wind-implanted noble gases. Data on the bulk chemistry, IR spectroscopy, cosmogenic nuclides, and organic components also indicate similarities to other metamorphosed LL chondrites. Noble gas studies reveal that the meteorite has a cosmic ray exposure (CRE) age of 36 ± 3 Ma and that most of the cosmogenic gases were produced in a meteoroid with a radius of at least 35 cm. This is larger than the size of the meteoroid which entered the Earth's atmosphere, which is constrained to <20 cm from short-lived radionuclide data. In combination, this might suggest a complex exposure history for Stubenberg.PostprintPeer reviewe
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