2,169 research outputs found

    Improvement of paraneoplastic limbic encephalitis after systemic treatment with rituximab in a patient with B-cell chronic lymphocytic leukemia

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    Limbic encephalitis is an inflammatory disease of the central nervous system characterized by diverse neurologic symptoms including mnestic disturbances, hallucinations, and seizures as well as behavioral symptoms like depression, personality changes, and acute confusional states resembling dementia. Several antibodies have been described in the pathogenesis of limbic encephalitis. It is often a paraneoplastic syndrome associated with small cell lung cancer, breast cancer, or Hodgkin's lymphoma among others. Here, we report a patient with B-cell chronic lymphocytic leukemia (B-CLL), presenting with otherwise unexplained neurologic symptoms consistent with limbic encephalitis. Despite intensive diagnostic procedures, no causing agent could be identified. Pleocytosis consisting of T cells was detected in the cerebrospinal fluid (CSF). We initiated anti-B-cell therapy with Rituximab for B-CLL with quick and durable resolution of symptoms. We speculate that disruption of interaction between autoreactive T and malignant B cells is responsible for the therapeutic effect of Rituximab

    Contribution of the Accretion Disk, Hot Corona, and Obscuring Torus to the Luminosity of Seyfert Galaxies: Integral and Spitzer Observations

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    We estimate the relative contributions of the supermassive black hole (SMBH) accretion disk, corona, and obscuring torus to the bolometric luminosity of Seyfert galaxies, using Spitzer mid-infrared (MIR) observations of a complete sample of 68 nearby active galactic nuclei (AGNs) from the INTEGRAL all-sky hard X-ray (HX) survey. This is the first HX-selected (above 15 keV) sample of AGNs with complementary high angular resolution, high signal-to-noise, MIR data. Correcting for the host galaxy contribution, we find a correlation between HX and MIR luminosities: L 15 ÎŒm∝L0.74 ± 0.06 HX. Assuming that the observed MIR emission is radiation from an accretion disk reprocessed in a surrounding dusty torus that subtends a solid angle decreasing with increasing luminosity (as inferred from the declining fraction of obscured AGNs), the intrinsic disk luminosity, L Disk, is approximately proportional to the luminosity of the corona in the 2-300 keV energy band, L Corona, with the L Disk/L Corona ratio varying by a factor of 2.1 around a mean value of 1.6. This ratio is a factor of ~2 smaller than for typical quasars producing the cosmic X-ray background. Therefore, over three orders of magnitude in luminosity, HX radiation carries a large, and roughly comparable, fraction of the bolometric output of AGNs. We estimate the cumulative bolometric luminosity density of local AGNs at ~(1-3) × 1040 erg s–1 Mpc–3. Finally, the Compton temperature ranges between kT c ≈ 2 and ≈6 keV for nearby AGNs, compared to kT c ≈ 2 keV for typical quasars, confirming that radiative heating of interstellar gas can play an important role in regulating SMBH growth

    Coherent electronic and nuclear dynamics in a rhodamine heterodimer-DNA supramolecular complex

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    Elucidating the role of quantum coherences in energy migration within biological and artificial multichromophoric antenna systems is the subject of an intense debate. It is also a practical matter because of the decisive implications for understanding the biological processes and engineering artificial materials for solar energy harvesting. A supramolecular rhodamine heterodimer on a DNA scaffold was suitably engineered to mimic the basic donor-acceptor unit of light-harvesting antennas. Ultrafast 2D electronic spectroscopic measurements allowed identifying clear features attributable to a coherent superposition of dimer electronic and vibrational states contributing to the coherent electronic charge beating between the donor and the acceptor. The frequency of electronic charge beating is found to be 970 cm-1 (34 fs) and can be observed for 150 fs. Through the support of high level ab initio TD-DFT computations of the entire dimer, we established that the vibrational modes preferentially optically accessed do not drive subsequent coupling between the electronic states on the 600 fs of the experiment. It was thereby possible to characterize the time scales of the early time femtosecond dynamics of the electronic coherence built by the optical excitation in a large rigid supramolecular system at a room temperature in solution. © 2017 the Owner Societies.Multi valued and parallel molecular logi

    Abundances in galactic H2 regions, 3: G25.4-0.2, G45.5+0.06, M8, S159 and DR22

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    Measurements of the ARII (6.99 microns), ArIII (8.99 microns), NeII (12.81 microns), SIII (18.71 microns), and SIV (10.51 microns) lines are presented for five compact HII regions along with continuum spectroscopy. From these data and radio data, lower limits to the elemental abundances of Ar, S, and Ne were deduced. The complex G25.4-0.2 is only 5.5 kpc from the galactic center, and is considerably overabundant in all these elements. Complex G45.5+0.06 is at seven kpc from the galactic center, and appears to be approximately consistent with solar abundance. The complex S159 in the Perseus Arm, at 12 kpc from the galactic center, has solar abundance, while M8 in the solar neighborhood may be somewhat overabundant in Ar and Ne. Complex DR 22, at 10 kpc from the galactic center in the Cygnus Arm, is overabundant in Ar. A summary of results from a series of papers on abundances is given

    Mid-infrared Identification of 6 cm Radio Source Counterparts in the Extended Groth Strip

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    A new 6-cm survey of almost 0.6 square degrees to a limit of 0.55-mJy/beam (10-sigma) finds 37 isolated radio sources and 7 radio source pairs (not necessarily physical companions). IRAC counterparts are identified for at least 92% of the radio sources within the area of deep IRAC coverage, which includes 31 isolated sources and 6 pairs. This contrasts with an identification rate of <74% to R<23.95 in visible light. Eight of the IRAC galaxies have power law spectral energy distributions, implying that the mid-infrared emission comes from a powerful AGN. The remaining 26 IRAC galaxies show stellar emission in the mid-infrared, probably in most of these galaxies because the stellar emission is bright enough to outshine an underlying AGN. The infrared colors suggest that the majority of these galaxies are bulge-dominated and have redshifts between approximately 0.5 and 1.0. Visible spectra from the DEEP2 redshift survey, available for 11 galaxies, are consistent with this suggestion. The IRAC galaxies fall into two distinct groups in a color-magnitude diagram, one group (the "stripe") includes all the AGN. The other group (the "blue clump") has blue 3.6 to 8 micron colors and a small range of 8 micron magnitudes. This separation should be useful in classifying galaxies found in other radio surveys.Comment: Accepted by A

    Spitzer/IRAC Observations of the Variability of Sgr A* and the Object G2 at 4.5 microns

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    We present the first detection from the Spitzer Space Telescope of 4.5 micron variability from Sgr A*, the emitting source associated with the Milky Way's central black hole. The >23 hour continuous light curve was obtained with the IRAC instrument in 2013 December. The result characterizes the variability of Sgr A* prior to the closest approach of the G2 object, a putative infalling gas cloud that orbits close to Sgr A*. The high stellar density at the location of Sgr A* produces a background of ~250 mJy at 4.5 microns in each pixel with a large pixel-to-pixel gradient, but the light curve for the highly variable Sgr A* source was successfully measured by modeling and removing the variations due to pointing wobble. The observed flux densities range from the noise level of ~0.7 mJy rms in a 6.4-s measurement to ~10 mJy. Emission was seen above the noise level ~34% of the time. The light curve characteristics, including the flux density distribution and structure function, are consistent with those previously derived at shorter infrared wavelengths. We see no evidence in the light curve for activity attributable to the G2 interaction at the observing epoch, ~100 days before the expected G2 periapsis passage. The IRAC light curve is more than a factor of two longer than any previous infrared observation, improving constraints on the timescale of the break in the power spectral distribution of Sgr A* flux densities. The data favor the longer of the two previously published values for the timescale.Comment: 13 pages, 10 figures, 2 tables, accepted for publication in the Ap

    Stabilization of Ultracold Molecules Using Optimal Control Theory

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    In recent experiments on ultracold matter, molecules have been produced from ultracold atoms by photoassociation, Feshbach resonances, and three-body recombination. The created molecules are translationally cold, but vibrationally highly excited. This will eventually lead them to be lost from the trap due to collisions. We propose shaped laser pulses to transfer these highly excited molecules to their ground vibrational level. Optimal control theory is employed to find the light field that will carry out this task with minimum intensity. We present results for the sodium dimer. The final target can be reached to within 99% if the initial guess field is physically motivated. We find that the optimal fields contain the transition frequencies required by a good Franck-Condon pumping scheme. The analysis is able to identify the ranges of intensity and pulse duration which are able to achieve this task before other competing process take place. Such a scheme could produce stable ultracold molecular samples or even stable molecular Bose-Einstein condensates

    The role of AGN in the colour transformation of galaxies at redshifts z~1

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    We explore the role of AGN in establishing and/or maintaining the bimodal colour distribution of galaxies by quenching their star-formation and hence, causing their transition from the blue to the red cloud. Important tests for this scenario include (i) the X-ray properties of galaxies in the transition zone between the two clouds and (ii) the incidence of AGN in post-starbursts, i.e. systems observed shortly after (<1Gyr) the termination of their star-formation. We perform these tests by combining deep Chandra observations with multiwavelength data from the AEGIS survey. Stacking the X-ray photons at the positions of galaxies (0.4<z<0.9) not individually detected at X-ray wavelengths suggests a population of obscured AGN among sources in the transition zone and in the red cloud. Their mean X-ray and mid-IR properties are consistent with moderately obscured low-luminosity AGN, Compton thick sources or a mix of both. Morphologies show that major mergers are unlikely to drive the evolution of this population but minor interactions may play a role. The incidence of obscured AGN in the red cloud (both direct detections and stacking results) suggests that BH accretion outlives the termination of the star-formation. This is also supported by our finding that post-starburst galaxies at z~0.8 and AGN are associated, in agreement with recent results at low-z. A large fraction of post-starbursts and red cloud galaxies show evidence for at least moderate levels of AGN obscuration. This implies that if AGN outflows cause the colour transformation of galaxies, then some nuclear gas and dust clouds either remain unaffected or relax to the central galaxy regions after the quenching their star-formation.Comment: Accepted for publication in MNRA

    Mode division multiplexing using an orbital angular momentum mode sorter and MIMO-DSP over a graded-index few-mode optical fibre

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    Mode division multiplexing (MDM)– using a multimode optical fiber’s N spatial modes as data channels to transmit N independent data streams – has received interest as it can potentially increase optical fiber data transmission capacity N-times with respect to single mode optical fibers. Two challenges of MDM are (1) designing mode (de)multiplexers with high mode selectivity (2) designing mode (de)multiplexers without cascaded beam splitting’s 1/N insertion loss. One spatial mode basis that has received interest is that of orbital angular momentum (OAM) modes. In this paper, using a device referred to as an OAM mode sorter, we show that OAM modes can be (de)multiplexed over a multimode optical fiber with higher than −15 dB mode selectivity and without cascaded beam splitting’s 1/N insertion loss. As a proof of concept, the OAM modes of the LP11 mode group (OAM−1,0 and OAM+1,0), each carrying 20-Gbit/s polarization division multiplexed and quadrature phase shift keyed data streams, are transmitted 5km over a graded-index, few-mode optical fibre. Channel crosstalk is mitigated using 4 × 4 multiple-input-multiple-output digital-signal-processing with &lt;1.5 dB power penalties at a bit-error-rate of 2 × 10−3
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