3,506 research outputs found
HID-1 controls formation of large dense core vesicles by influencing cargo sorting and trans-Golgi network acidification
Large dense core vesicles (LDCVs) mediate the regulated release of neuropeptides and peptide hormones. They form at the trans-Golgi network (TGN), where their soluble content aggregates to form a dense core, but the mechanisms controlling biogenesis are still not completely understood. Recent studies have implicated the peripheral membrane protein HID-1 in neuropeptide sorting and insulin secretion. Using CRISPR/Cas9, we generated HID-1 KO rat neuroendocrine cells, and we show that the absence of HID-1 results in specific defects in peptide hormone and monoamine storage and regulated secretion. Loss of HID-1 causes a reduction in the number of LDCVs and affects their morphology and biochemical properties, due to impaired cargo sorting and dense core formation. HID-1 KO cells also exhibit defects in TGN acidification together with mislocalization of the Golgi-enriched vacuolar H+-ATPase subunit isoform a2. We propose that HID-1 influences early steps in LDCV formation by controlling dense core formation at the TGN.</jats:p
Concert recording 2018-04-08a
[Track 1]. Sonatina. 1. [Track 2]. 2. [Track 3]. 3. / Halsey Stevens -- [Track 4]. Songs of a wayfarer. I. Wenn mein Schatz Hochzeit macht [Track 5]. II. Ging heut Morgen uber\u27s Feld [Track 6]. III. Ich hab\u27 ein gluhend Messer [Track 7]. IV. Die Zwei Blauen Augen / Gustav Mahler -- [Track 8]. Sonata in F minor. I. Andante cantabile [Track 9]. II. Allegro [Track 10]. III. Andante / Georg Philipp Telemann -- [Track 11]. 10 pieces for two bass trombones. 1. The hitch hiker [Track 12]. 6. Cashmere [Track 13]. 8. Below 10 street / Tommy Pederson -- [Track 14]. Gospel time / Jeffrey Agrell
Thirty New Low-Mass Spectroscopic Binaries
As part of our search for young M dwarfs within 25 pc, we acquired
high-resolution spectra of 185 low-mass stars compiled by the NStars project
that have strong X-ray emission. By cross-correlating these spectra with radial
velocity standard stars, we are sensitive to finding multi-lined spectroscopic
binaries. We find a low-mass spectroscopic binary fraction of 16% consisting of
27 SB2s, 2 SB3s and 1 SB4, increasing the number of known low-mass SBs by 50%
and proving that strong X-ray emission is an extremely efficient way to find
M-dwarf SBs. WASP photometry of 23 of these systems revealed two low-mass EBs,
bringing the count of known M dwarf EBs to 15. BD -22 5866, the SB4, is fully
described in Shkolnik et al. 2008 and CCDM J04404+3127 B consists of a two
mid-M stars orbiting each other every 2.048 days. WASP also provided rotation
periods for 12 systems, and in the cases where the synchronization time scales
are short, we used P_rot to determine the true orbital parameters. For those
with no P_rot, we use differential radial velocities to set upper limits on
orbital periods and semi-major axes. More than half of our sample has
near-equal-mass components (q > 0.8). This is expected since our sample is
biased towards tight orbits where saturated X-ray emission is due to tidal
spin-up rather than stellar youth. Increasing the samples of M dwarf SBs and
EBs is extremely valuable in setting constraints on current theories of stellar
multiplicity and evolution scenarios for low-mass multiple systems.Comment: Accepted to Ap
Optical data of meteoritic nano-diamonds from far-ultraviolet to far-infrared wavelengths
We have used different spectroscopic techniques to obtain a consistent
quantitative absorption spectrum of a sample of meteoritic nano-diamonds in the
wavelength range from the vacuum ultraviolet (0.12 m) to the far infrared
(100 m). The nano-diamonds have been isolated by a chemical treatment from
the Allende meteorite (Braatz et al.2000). Electron energy loss spectroscopy
(EELS) extends the optical measurements to higher energies and allows the
derivation of the optical constants (n & k) by Kramers-Kronig analysis. The
results can be used to restrain observations and to improve current models of
the environment where the nano-diamonds are expected to have formed. We also
show that the amount of nano-diamond which can be present in space is higher
than previously estimated by Lewis et al. (1989).Comment: 11 pages, 7 figure
A multiwavelength study of Swift GRB 060111B constraining the origin of its prompt optical emission
In this work, we present the results obtained from a multi-wavelength
campaign, as well as from the public Swift/BAT, XRT, and UVOT data of GRB
060111B for which a bright optical emission was measured with good temporal
resolution during the prompt phase. We identified the host galaxy at R~25 mag;
its featureless spectral continuum and brightness, as well as the non-detection
of any associated supernova 16 days after the trigger and other independent
redshift estimates, converge to z~1-2. From the analysis of the early afterglow
SED, we find that non-negligible host galaxy dust extinction, in addition to
the Galactic one, affects the observed flux in the optical regime. The
extinction-corrected optical-to-gamma-ray spectral energy distribution during
the prompt emission shows a flux density ratio =0.01-0.0001
with spectral index , strongly suggesting a
separate origin of the optical and gamma-ray components. This result is
supported by the lack of correlated behavior in the prompt emission light
curves observed in the two energy domains. The properties of the prompt optical
emission observed during GRB 060111B favor interpretation of this optical light
as radiation from the reverse shock in a thick shell limit and in the slow
cooling regime. The expected peak flux is consistent with the observed one
corrected for the host extinction, likely indicating that the starting time of
the TAROT observations is very near to or coincident with the peak time. The
estimated fireball initial Lorentz factor is >260-360 at z=1-2, similar to the
Lorentz factors obtained from other GRBs. GRB 060111B is a rare, good test case
of the reverse shock emission mechanism in both the X-ray and optical energy
ranges.Comment: Accepted for publication in Astronomy and Astrophysics, 15 pages,10
figures and 7 table
Prostatic Acid Phosphatase Is Required for the Antinociceptive Effects of Thiamine and Benfotiamine
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Calibration of the charge and energy loss per unit length of the MicroBooNE liquid argon time projection chamber using muons and protons
We describe a method used to calibrate the position- and time-dependent response of the MicroBooNE liquid argon time projection chamber anode wires to ionization particle energy loss. The method makes use of crossing cosmic-ray muons to partially correct anode wire signals for multiple effects as a function of time and position, including cross-connected TPC wires, space charge effects, electron attachment to impurities, diffusion, and recombination. The overall energy scale is then determined using fully-contained beam-induced muons originating and stopping in the active region of the detector. Using this method, we obtain an absolute energy scale uncertainty of 2% in data. We use stopping protons to further refine the relation between the measured charge and the energy loss for highly-ionizing particles. This data-driven detector calibration improves both the measurement of total deposited energy and particle identification based on energy loss per unit length as a function of residual range. As an example, the proton selection efficiency is increased by 2% after detector calibration
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Reconstruction and measurement of (100) MeV energy electromagnetic activity from π0 arrow γγ decays in the MicroBooNE LArTPC
We present results on the reconstruction of electromagnetic (EM) activity from photons produced in charged current νμ interactions with final state π0s. We employ a fully-automated reconstruction chain capable of identifying EM showers of (100) MeV energy, relying on a combination of traditional reconstruction techniques together with novel machine-learning approaches. These studies demonstrate good energy resolution, and good agreement between data and simulation, relying on the reconstructed invariant π0 mass and other photon distributions for validation. The reconstruction techniques developed are applied to a selection of νμ + Ar → μ + π0 + X candidate events to demonstrate the potential for calorimetric separation of photons from electrons and reconstruction of π0 kinematics
A faint optical flash in dust-obscured GRB 080603A - implications for GRB prompt emission mechanisms
We report the detection of a faint optical flash by the 2-m Faulkes Telescope
North simultaneously with the second of two prompt gamma-ray pulses in INTEGRAL
gamma-ray burst (GRB) 080603A, beginning at t_rest = 37 s after the onset of
the GRB. This optical flash appears to be distinct from the subsequent emerging
afterglow emission, for which we present comprehensive broadband radio to X-ray
light curves to 13 days post-burst and rigorously test the standard fireball
model. The intrinsic extinction toward GRB 080603A is high (A_V,z = 0.8 mag),
and the well-sampled X-ray-to-near-infrared spectral energy distribution is
interesting in requiring an LMC2 extinction profile, in contrast to the
majority of GRBs. Comparison of the gamma-ray and extinction-corrected optical
flux densities of the flash rules out an inverse-Compton origin for the prompt
gamma-rays; instead, we suggest that the optical flash could originate from the
inhomogeneity of the relativistic flow. In this scenario, a large velocity
irregularity in the flow produces the prompt gamma-rays, followed by a milder
internal shock at a larger radius that would cause the optical flash. Flat
gamma-ray spectra, roughly F propto nu^-0.1, are observed in many GRBs. If the
flat spectrum extends down to the optical band in GRB 080603A, the optical
flare could be explained as the low-energy tail of the gamma-ray emission. If
this is indeed the case, it provides an important clue to understanding the
nature of the emission process in the prompt phase of GRBs and highlights the
importance of deep (R> 20 mag), rapid follow-up observations capable of
detecting faint, prompt optical emission.Comment: 22 pages, 11 figures, accepted to MNRA
Design and construction of the MicroBooNE Cosmic Ray Tagger system
The MicroBooNE detector utilizes a liquid argon time projection chamber
(LArTPC) with an 85 t active mass to study neutrino interactions along the
Booster Neutrino Beam (BNB) at Fermilab. With a deployment location near ground
level, the detector records many cosmic muon tracks in each beam-related
detector trigger that can be misidentified as signals of interest. To reduce
these cosmogenic backgrounds, we have designed and constructed a TPC-external
Cosmic Ray Tagger (CRT). This sub-system was developed by the Laboratory for
High Energy Physics (LHEP), Albert Einstein center for fundamental physics,
University of Bern. The system utilizes plastic scintillation modules to
provide precise time and position information for TPC-traversing particles.
Successful matching of TPC tracks and CRT data will allow us to reduce
cosmogenic background and better characterize the light collection system and
LArTPC data using cosmic muons. In this paper we describe the design and
installation of the MicroBooNE CRT system and provide an overview of a series
of tests done to verify the proper operation of the system and its components
during installation, commissioning, and physics data-taking
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