283 research outputs found

    Particle acceleration due to shocks in the interplanetary field: High time resolution data and simulation results

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    Data were examined from two experiments aboard the Explorer 50 (IMP 8) spacecraft. The Johns Hopkins University/Applied Lab Charged Particle Measurement Experiment (CPME) provides 10.12 second resolution ion and electron count rates as well as 5.5 minute or longer averages of the same, with data sampled in the ecliptic plane. The high time resolution of the data allows for an explicit, point by point, merging of the magnetic field and particle data and thus a close examination of the pre- and post-shock conditions and particle fluxes associated with large angle oblique shocks in the interplanetary field. A computer simulation has been developed wherein sample particle trajectories, taken from observed fluxes, are allowed to interact with a planar shock either forward or backward in time. One event, the 1974 Day 312 shock, is examined in detail

    Compact 20-pass thin-disk amplifier insensitive to thermal lensing

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    We present a multi-pass amplifier which passively compensates for distortions of the spherical phase front occurring in the active medium. The design is based on the Fourier transform propagation which makes the output beam parameters insensitive to variation of thermal lens effects in the active medium. The realized system allows for 20 reflections on the active medium and delivers a small signal gain of 30 with M2^2 = 1.16. Its novel geometry combining Fourier transform propagations with 4f-imaging stages as well as a compact array of adjustable mirrors allows for a layout with a footprint of 400 mm x 1000 mm.Comment: 7 pages, 6 figure

    Synthese und strukturelle Charakterisierung von Bis(pentamethylcyclopentadienylmolybdĂ€n-ÎŒ-sulfido)-Komplexen mit ÎŒ,η1-SSR-Liganden(= SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF BIS(PENTAMETHYLCYCLOPENTADIENYLMOLYBDENUM-MU-SULFIDO) COMPLEXES WITH MU,ETA-1-SSR LIGANDS)

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    The reaction of Cp2*Mo2S4I2(Cp* = eta(5)-C5Me5) with two equivalents of NaSR (R = Me, (i)Pr, (t)Bu, Ph) gives the complexes Cp2*Mo2(mu,eta(1)-SSR)2(mu-S)2 (2a-d) in nearly quantitative yields. The compounds have been investigated spectroscopically and in the case of R = Ph (2d) by means of X-ray diffraction analysis. The results show the presence of two eta(1)-PhSS- bridges (d(s-s) 2.139(2) angstrom) and that exclusively the trans-isomer is formed. All sulfur atoms lie in one plane perpendicular to the Mo-Mo axis and bisecting it

    Accumulation of oligomer-prone α-synuclein exacerbates synaptic and neuronal degeneration in vivo

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    The toxicity of α-synuclein invivo is not well understood. Rockenstein etal. describe an α-synuclein transgenic model expressing the E57K mutant that forms stable oligomers. They show that oligomers accumulate at synapses and that the mutation interferes with synaptic vesicles and is associated with behavioural deficits and neurodegeneratio

    Brain functional connectivity alterations associated with neuropsychological performance 6-9 months following SARS-CoV-2 infection.

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    Neuropsychological deficits and brain damage following SARS-CoV-2 infection are not well understood. Then, 116 patients, with either severe, moderate, or mild disease in the acute phase underwent neuropsychological and olfactory tests, as well as completed psychiatric and respiratory questionnaires at 223 ± 42 days postinfection. Additionally, a subgroup of 50 patients underwent functional magnetic resonance imaging. Patients in the severe group displayed poorer verbal episodic memory performances, and moderate patients had reduced mental flexibility. Neuroimaging revealed patterns of hypofunctional and hyperfunctional connectivities in severe patients, while only hyperconnectivity patterns were observed for moderate. The default mode, somatosensory, dorsal attention, subcortical, and cerebellar networks were implicated. Partial least squares correlations analysis confirmed specific association between memory, executive functions performances and brain functional connectivity. The severity of the infection in the acute phase is a predictor of neuropsychological performance 6-9 months following SARS-CoV-2 infection. SARS-CoV-2 infection causes long-term memory and executive dysfunctions, related to large-scale functional brain connectivity alterations

    Desmocollin switching in colorectal cancer

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    The desmocollins are members of the desmosomal cadherin family of cell–cell adhesion molecules. They are essential constituents of desmosomes, intercellular junctions that play a critical role in the maintenance of tissue integrity in epithelia and cardiac muscle. In humans, three desmocollins (Dsc1, Dsc2 and Dsc3) have been described. The desmocollins exhibit tissue-specific patterns of expression; only Dsc2 is expressed in normal colonic epithelium. We have found switching between desmocollins in sporadic colorectal adenocarcinoma with a reduction in Dsc2 protein (in 8/16 samples analysed by immunohistochemistry) being accompanied by de novo expression of Dsc1 (16/16) and Dsc3 (7/16). Similar results were obtained by western blotting of a further 16 samples. No change was found in Dsc2 mRNA, but de novo expression of Dscs 1 and 3 was accompanied by increased message levels. Loss of Dsc2 (8/19) and de novo expression of Dsc1 (11/19) and Dsc3 (6/19) was also found in colorectal adenocarcinomas on a background of colitis. The data raise the possibility that switching of desmocollins could play an important role in the development of colorectal cancer

    Expression of MAGE-C1/CT7 and MAGE-C2/CT10 Predicts Lymph Node Metastasis in Melanoma Patients

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    MAGE-C1/CT7 and MAGE-C2/CT10 are members of the large MAGE family of cancer-testis (CT) antigens. CT antigens are promising targets for immunotherapy in cancer because their expression is restricted to cancer and germ line cells and a proportion of cancer patients presents with immune responses against CT antigens, which clearly demonstrates their immunogenicity. This study investigates the expression of MAGE-C1/CT7 and MAGE-C2/CT10 in primary and metastatic melanoma. Immunohistochemical staining of tissue microarrays that consisted of 59 primary malignant melanomas of the skin, 163 lymph node and distant melanoma metastases and 68 melanoma cell lines was performed. We found MAGE-C1/CT7 expression in 15 out of 50 (24%) primary melanomas and 15 out of 50 (24%) cell lines, whereas MAGE-C2/CT10 was detected in 17 out of 51 (33%) primary melanomas and 14 out of 68 (17%) cell lines. MAGE-C1/CT7 and MAGE-C2/CT10 were both detected in 40% of melanoma metastases. Patients with MAGE-C1/CT7 or MAGE-C2/CT10 positive primary melanoma had significantly more lymph node metastases (p = 0.005 and p<0.001, resp.). Prediction of lymph node metastasis by MAGE-C1/CT7 and MAGE-C2/CT10 was independent of tumor cell proliferation rate (Ki67 labeling index) in a multivariate analysis (p = 0.01). Our results suggest that the expression of MAGE-C1/CT7 and MAGE-C2/CT10 in primary melanoma is a potent predictor of sentinel lymph node metastasis
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