415 research outputs found
Development of super broadband interferometer in FIR
We are developing the super broad band interferometer by applying the Fourier
Transform Spectrometer(FTS) to aperture synthesis system in mm and sub-mm
bands. We have constructed a compact system based on the Martin and Puplett
type Fourier Transform spectrometer (MP-FT). We call this equipment
Multi-Fourier Transform interferometer (MuFT). The band width of the system can
be extended as large as one wants contrary to the severely limited band width
of the usual interferometer due to the speed of the AD converter. The direct
detectors, e.g. bolometer, SIS video detector, can be used as the focal plane
detectors. This type of detectors have a great advantage in FIR band since they
are free from the quantum limit of the noise which limits the sensitivity of
the heterodyne detectors used in the usual interferometers. Further, the direct
detectors are able to make a large format array contrary to the heterodyne
detectors for which construction of a large format array is practically
difficult. These three characteristics make one be possible to develop high
sensitive super broad band FIR interferometer with wide field of view. In the
laboratory experiments, we have succeeded in measuring the spectroscopically
resolved 2D image of the source in 150GHz-900GHz band. The future application
of this technique to the observations from the space could open new interesting
possibilities in FIR astronomy.Comment: 9 pages, presented at the Glasgow SPIE conference "Optical, Infrared,
and Millimeter Space Telescopes", to appear in Proc. SPIE, vol. #5487-20
Differential functions of G protein and BazāaPKC signaling pathways in Drosophila neuroblast asymmetric division
Drosophila melanogaster neuroblasts (NBs) undergo asymmetric divisions during which cell-fate determinants localize asymmetrically, mitotic spindles orient along the apicalābasal axis, and unequal-sized daughter cells appear. We identified here the first Drosophila mutant in the GĪ³1 subunit of heterotrimeric G protein, which produces GĪ³1 lacking its membrane anchor site and exhibits phenotypes identical to those of GĪ²13F, including abnormal spindle asymmetry and spindle orientation in NB divisions. This mutant fails to bind GĪ²13F to the membrane, indicating an essential role of cortical GĪ³1āGĪ²13F signaling in asymmetric divisions. In GĪ³1 and GĪ²13F mutant NBs, PinsāGĪ±i, which normally localize in the apical cortex, no longer distribute asymmetrically. However, the other apical components, Bazookaāatypical PKCāPar6āInscuteable, still remain polarized and responsible for asymmetric Miranda localization, suggesting their dominant role in localizing cell-fate determinants. Further analysis of GĪ²Ī³ and other mutants indicates a predominant role of Partner of InscuteableāGĪ±i in spindle orientation. We thus suggest that the two apical signaling pathways have overlapping but different roles in asymmetric NB division
Automated bone marrow analysis using the CD4000 automated haematology analyser
At present, bone marrow analysis is performed microscopically, but is time consuming and labour intensive. No automated methods have been successfully applied to classification of bone marrows cells because automated blood cell analysers have been incapable of identifying erythroblasts. The present study was designed to evaluate automated analysis of bone marrow aspirates with the CELL-DYN 4000 (CD4000) haematology analyser, which enables automated determination of erythroblast counts in both the normal mode (haemolytic time; 11.5s) and the resistant RBC mode (34.0s). The percentages of subpopulations including lymphocytes, neutrophils and erythroblasts were obtained with the CD4000, and as a reference, differential counts by microscopic observation of MayāGrĆ¼nwaldāGiesa-stained films of bone marrow aspirates were performed (n=98). Significant correlations (P < 0.01) between the results obtained with the two methods were observed for total nucleated cell count and lymphocytes, neutrophils, erythroblasts and myeloid/erythroid (M/E) ratio. However, there were biases in the average percentages of erythroblasts, lymphocytes and M/E ratio obtained using the normal mode with the CD4000 toward values lower than those obtained with the microscopic method. Using the RBC resistant mode with the CD4000, the average percentages of erythroblasts, lymphocytes and M/E ratio approximated those obtained with the microscopic method. In conclusion, the CD4000 in resistant RBC mode is more useful for analysis of bone marrow aspirates than is the normal mode, because the former better approximates the M/E ratio than the latter
Comparative proteomic analysis of Salmonella enterica serovar Typhimurium ppGpp-deficient mutant to identify a novel virulence protein required for intracellular survival in macrophages
<p>Abstract</p> <p>Background</p> <p>The global ppGpp-mediated stringent response in pathogenic bacteria plays an important role in the pathogenesis of bacterial infections. In <it>Salmonella enterica </it>serovar Typhimurium (<it>S</it>. Typhimurium), several genes, including virulence genes, are regulated by ppGpp when bacteria are under the stringent response. To understand the control of virulence genes by ppGpp in <it>S</it>. Typhimurium, agarose 2-dimensional electrophoresis (2-DE) combined with mass spectrometry was used and a comprehensive 2-DE reference map of amino acid-starved <it>S</it>. Typhimurium strain SH100, a derivative of ATCC 14028, was established.</p> <p>Results</p> <p>Of the 366 examined spots, 269 proteins were successfully identified. The comparative analysis of the wild-type and ppGpp<sup>0 </sup>mutant strains revealed 55 proteins, the expression patterns of which were affected by ppGpp. Using a mouse infection model, we further identified a novel virulence-associated factor, STM3169, from the ppGpp-regulated and <it>Salmonella</it>-specific proteins. In addition, <it>Salmonella </it>strains carrying mutations in the gene encoding STM3169 showed growth defects and impaired growth within macrophage-like RAW264.7 cells. Furthermore, we found that expression of <it>stm3169 </it>was controlled by ppGpp and SsrB, a response regulator of the two-component system located on <it>Salmonella </it>pathogenicity island 2.</p> <p>Conclusions</p> <p>A proteomic approach using a 2-DE reference map can prove a powerful tool for analyzing virulence factors and the regulatory network involved in <it>Salmonella </it>pathogenesis. Our results also provide evidence of a global response mediated by ppGpp in <it>S. enterica</it>.</p
The nonlinear redshift space probability distribution function in models with local primordial non-Gaussianity
We use the ellipsoidal collapse approximation to investigate the nonlinear
redshift space evolution of the density field with primordial non-Gaussianity
of the local f_{nl}-type. We utilize the joint distribution of eigenvalues of
the initial non-Gaussian shear field and evaluate the evolved redshift space
probability distribution function (PDF). It is shown that, similar to the real
space analysis, the underdense tail of the nonlinear redshift space PDF differs
significantly from that for Gaussian initial conditions. We also derive the
lowest order correction of the Kaiser's formulain the presence of a non-zero
f_{nl}.Comment: Matched version accepted by MNRA
Very compact millimeter sizes for composite star-forming/AGN submillimeter galaxies
We report the study of far-IR sizes of submillimeter galaxies (SMGs) in
relation to their dust-obscured star formation rate (SFR) and active galactic
nuclei (AGN) presence, determined using mid-IR photometry. We determined the
millimeter-wave (m) sizes of 69 ALMA-identified
SMGs, selected with confidence on ALMA images (--7.4 mJy). We found that all the SMGs are located above an
avoidance region in the millimeter size-flux plane, as expected by the
Eddington limit for star formation. In order to understand what drives the
different millimeter-wave sizes in SMGs, we investigated the relation between
millimeter-wave size and AGN fraction for 25 of our SMGs at --3. We found
that the SMGs for which the mid-IR emission is dominated by star formation or
AGN have extended millimeter-sizes, with respective median and 1.5 kpc. Instead, the SMGs for which
the mid-IR emission corresponds to star-forming/AGN composites have more
compact millimeter-wave sizes, with median
kpc. The relation between millimeter-wave size and AGN fraction suggests that
this size may be related to the evolutionary stage of the SMG. The very compact
sizes for composite star-forming/AGN systems could be explained by supermassive
black holes growing rapidly during the SMG coalescing, star-formation phase.Comment: 9 pages, 4 figures, 1 table. Accepted for publication in ApJ Lette
SXDF-ALMA 2 Arcmin^2 Deep Survey: Resolving and Characterizing the Infrared Extragalactic Background Light Down to 0.5 mJy
We present a multi-wavelength analysis of five submillimeter sources (S_1.1mm
= 0.54-2.02 mJy) that were detected during our 1.1-mm-deep continuum survey in
the SXDF-UDS-CANDELS field (2 arcmin^2, 1sigma = 0.055 mJy beam^-1) using the
Atacama Large Millimeter/submillimeter Array (ALMA). The two brightest sources
correspond to a known single-dish (AzTEC) selected bright submillimeter galaxy
(SMG), whereas the remaining three are faint SMGs newly uncovered by ALMA. If
we exclude the two brightest sources, the contribution of the ALMA-detected
faint SMGs to the infrared extragalactic background light is estimated to be ~
4.1^{+5.4}_{-3.0} Jy deg^{-2}, which corresponds to ~ 16^{+22}_{-12}% of the
infrared extragalactic background light. This suggests that their contribution
to the infrared extragalactic background light is as large as that of bright
SMGs. We identified multi-wavelength counterparts of the five ALMA sources. One
of the sources (SXDF-ALMA3) is extremely faint in the optical to near-infrared
region despite its infrared luminosity (L_IR ~ 1e12 L_sun or SFR ~ 100 M_sun
yr^{-1}). By fitting the spectral energy distributions (SEDs) at the
optical-to-near-infrared wavelengths of the remaining four ALMA sources, we
obtained the photometric redshifts (z_photo) and stellar masses (M_*): z_photo
~ 1.3-2.5, M_* ~ (3.5-9.5)e10 M_sun. We also derived their star formation rates
(SFRs) and specific SFRs (sSFRs) as ~ 30-200 M_sun yr^{-1} and ~ 0.8-2
Gyr^{-1}, respectively. These values imply that they are main-sequence
star-forming galaxies.Comment: PASJ accepted, 15 pages, 6 figures, 2 table
iPSC-Based Compound Screening and In Vitro Trials Identify a Synergistic Anti-amyloid Ī² Combination for Alzheimerās Disease
In the process of drug development, in vitro studies do not always adequately predict human-specific drug responsiveness in clinical trials. Here, we applied the advantage of human iPSC-derived neurons, which offer human-specific drug responsiveness, to screen and evaluate therapeutic candidates for Alzheimerās disease (AD). Using AD patient neurons with nearly 100% purity from iPSCs, we established a robust and reproducible assay for amyloid Ī² peptide (AĪ²), a pathogenic molecule in AD, and screened a pharmaceutical compound library. We acquired 27 AĪ²-lowering screen hits, prioritized hits by chemical structure-based clustering, and selected 6 leading compounds. Next, to maximize the anti-AĪ² effect, we selected a synergistic combination of bromocriptine, cromolyn, and topiramate as an anti-AĪ² cocktail. Finally, using neurons from familial and sporadic AD patients, we found that the cocktail showed a significant and potent anti-AĪ² effect on patient cells. This human iPSC-based platform promises to be useful for AD drug development
Nuclear Quadrupole Resonance Frequency in Multi-Layered Cuprates
The 63Cu nuclear quadrupole resonance (NQR) frequency, nu_q, in the
multi-layered cuprates is calculated in the cluster model by the exact
diagonalization method. The charge imbalance between the outer CuO_2 plane (OP)
with apical oxygen (OA) and the inner plane (IP) without OA in three-layered
Tl2223 is estimated by comparing our results with the experimental nu_q. In
Tl-based cuprates with more than three layers, we predict a large enhancement
of the splitting of nu_q between OP and IP by taking into account the reduction
of bond length between Cu and OA and a resulting enhancement of the charge
transfer energy. Our results show that the NQR frequency is a useful quantity
to estimate the charge imbalance in the multi-layered cuprates.Comment: 4 pages, 5 figure
Compact starbursts in z~3-6 submillimeter galaxies revealed by ALMA
We report the source size distribution, as measured by ALMA millimetric
continuum imaging, of a sample of 13 AzTEC-selected submillimeter galaxies
(SMGs) at z_photo ~ 3-6. Their infrared luminosities and star-formation rates
(SFR) are L_IR ~ 2-6 x 10^12 L_sun and ~ 200-600 M_sun yr-1, respectively. The
size of z ~ 3-6 SMGs ranges from 0".10 to 0".38 with a median of
0".20+0".03-0".05 (FWHM), corresponding to a median circularized effective
radius (Rc,e) of 0.67+0.13-0.14 kpc, comparable to the typical size of the
stellar component measured in compact quiescent galaxies at z ~ 2 (cQGs) --- R
~ 1 kpc. The median surface SFR density of our z ~ 3-6 SMGs is 100+42-26 M_sun
yr-1 kpc-2, comparable to that seen in local merger-driven (U)LIRGsrather than
in extended disk galaxies at low and high redshifts. The discovery of compact
starbursts in z >~ 3 SMGs strongly supports a massive galaxy formation scenario
wherein z ~ 3-6 SMGs evolve into the compact stellar components of z ~ 2 cQGs.
These cQGs are then thought to evolve into the most massive ellipticals in the
local Universe, mostly via dry mergers. Our results thus suggest that z >~ 3
SMGs are the likely progenitors of massive local ellipticals, via cQGs, meaning
that we can now trace the evolutionary path of the most massive galaxies over a
period encompassing ~ 90% of the age of the Universe.Comment: 12 pages, 10 figures, accepted to the Astrophysical Journal part
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