684 research outputs found
Application of thermoluminescence for detection of cascade shower 1: Hardware and software of reader system
A reader system for the detection of cascade showers via luminescence induced by heating sensitive material (BaSO4:Eu) is developed. The reader system is composed of following six instruments: (1) heater, (2) light guide, (3) image intensifier, (4) CCD camera, (5) image processor, (6) microcomputer. The efficiency of these apparatuses and software application for image analysis is reported
Application of thermoluminescence for detection of cascade shower 2: Detection of cosmic ray cascade shower at Mount Fuji
The results of a thermoluminescence (TL) chamber exposed at Mt. Fuji during Aug. '83 - Aug. '84 are reported. The TL signal induced by cosmic ray shower is detected and compared with the spot darkness of X-ray film exposed at the same time
Exploration of Finite 2D Square Grid by a Metamorphic Robotic System
We consider exploration of finite 2D square grid by a metamorphic robotic
system consisting of anonymous oblivious modules. The number of possible shapes
of a metamorphic robotic system grows as the number of modules increases. The
shape of the system serves as its memory and shows its functionality. We
consider the effect of global compass on the minimum number of modules
necessary to explore a finite 2D square grid. We show that if the modules agree
on the directions (north, south, east, and west), three modules are necessary
and sufficient for exploration from an arbitrary initial configuration,
otherwise five modules are necessary and sufficient for restricted initial
configurations
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Fused in sarcoma silences HIV gene transcription and maintains viral latency through suppressing AFF4 gene activation
Background: The human immunodeficiency virus (HIV) cell reservoir is currently a main obstacle towards complete eradication of the virus. This infected pool is refractory to anti-viral therapy and harbors integrated proviruses that are transcriptionally repressed but replication competent. As transcription silencing is key for establishing the HIV reservoir, significant efforts have been made to understand the mechanism that regulate HIV gene transcription, and the role of the elongation machinery in promoting this step. However, while the role of the super elongation complex (SEC) in enhancing transcription activation of HIV is well established, the function of SEC in modulating viral latency is less defined and its cell partners are yet to be identified. Results: In this study we identify fused in sarcoma (FUS) as a partner of AFF4 in cells. FUS inhibits the activation of HIV transcription by AFF4 and ELL2, and silences overall HIV gene transcription. Concordantly, depletion of FUS elevates the occupancy of AFF4 and Cdk9 on the viral promoter and activates HIV gene transcription. Live cell imaging demonstrates that FUS co-localizes with AFF4 within nuclear punctuated condensates, which are disrupted upon treating cells with aliphatic alcohol. In HIV infected cells, knockout of FUS delays the gradual entry of HIV into latency, and similarly promotes viral activation in a T cell latency model that is treated with JQ1. Finally, effects of FUS on HIV gene transcription are also exhibited genome wide, where FUS mainly occupies gene promoters at transcription starting sites, while its knockdown leads to an increase in AFF4 and Cdk9 occupancy on gene promoters of FUS affected genes. Conclusions: Towards eliminating the HIV infected reservoir, understanding the mechanisms by which the virus persists in the face of therapy is important. Our observations show that FUS regulates both HIV and global gene transcription and modulates viral latency, thus can potentially serve as a target for future therapy that sets to reactivate HIV from its latent state.Israel Science Foundation [755/17]; Ben-Gurion University of the Negev, Israel; National Institute of Health [NS082376]; Office of the Director of the NIH [S10OD013237]; NIH [R21AI127274]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Auxiliary-level-assisted operations with charge qubits in semiconductors
We present a new scheme for rotations of a charge qubit associated with a
singly ionized pair of donor atoms in a semiconductor host. The logical states
of such a qubit proposed recently by Hollenberg et al. are defined by the
lowest two energy states of the remaining valence electron localized around one
or another donor. We show that an electron located initially at one donor site
can be transferred to another donor site via an auxiliary molecular level
formed upon the hybridization of the excited states of two donors. The electron
transfer is driven by a single resonant microwave pulse in the case that the
energies of the lowest donor states coincide or two resonant pulses in the case
that they differ from each other. Depending on the pulse parameters, various
one-qubit operations, including the phase gate, the NOT gate, and the Hadamard
gate, can be realized in short times. Decoherence of an electron due to the
interaction with acoustic phonons is analyzed and shown to be weak enough for
coherent qubit manipulation being possible, at least in the proof-of-principle
experiments on one-qubit devices.Comment: Extended version of cond-mat/0411605 with detailed discussion of
phonon-induced decoherence including dephasing and relaxation; to be
published in JET
Volume reduction of municipal solid wastes contaminated with radioactive cesium by ferrocyanide coprecipitation technique
Municipal solid wastes (MSW) with elevated concentrations of radioactive cesium (rad-Cs hereafter) have been generated in some areas of Japan in the aftermath of the Fukushima Daiichi Nuclear Power Plant (F1 hereafter) accident. Both recycling and final disposal of the contaminated MSW have become a difficult problem in the affected areas, resulting in accumulation of treated residues in the treatment facilities. The rad-Cs in MSW, especially fly ash, often showed a high leaching rate. Extraction of contaminated MSW with water or hot oxalic acid followed by selective removal of rad-Cs from the extract using ferrocyanide (Fer hereafter) coprecipitation technique could be an ultimate solution for waste volume reduction. The MSW extracts contain various metal components as well as chelating reagents like oxalic acid, and are often very saline. The composition of the extract varies widely depending on waste sources, applied treatment techniques, and rad-Cs extraction method etc. The applicability of the Fer coprecipitation technique had to be tested and validated before it could be applied for actual treatment. In this work, we applied the Fer technique and observed removal of cesium (Cs) from water and oxalic acid extracts (all spiked with rad-Cs tracer or stable Cs) of various MSW samples collected from uncontaminated areas. Finally, the Fer technique was applied on site for removal of rad-Cs in the extracts of contaminated MSW. By modifying coprecipitation conditions according to solution matrix, Cs removal rates of higher than 95 % could be obtained
Using small molecules to facilitate exchange of bicarbonate and chloride anions across liposomal membranes
Bicarbonate is involved in a wide range of biological processes, which include respiration, regulation of intracellular pH and fertilization. In this study we use a combination of NMR spectroscopy and ion-selective electrode techniques to show that the natural product prodigiosin, a tripyrrolic molecule produced by microorganisms such as Streptomyces and Serratia, facilitates chloride/bicarbonate exchange (antiport) across liposomal membranes. Higher concentrations of simple synthetic molecules based on a 4,6-dihydroxyisophthalamide core are also shown to facilitate this antiport process. Although it is well known that proteins regulate Cl-/HCO3- exchange in cells, these results suggest that small molecules may also be able to regulate the concentration of these anions in biological systems
The secretion inhibitor Exo2 perturbs trafficking of Shiga toxin between endosomes and the trans-Golgi network
The small-molecule inhibitor Exo2 {4-hydroxy-3-methoxy-(5,6,7,8-tetrahydrol[1]benzothieno[2,3-d]pyrimidin-4-yl)hydraz-one benzaldehyde} has been reported to disrupt the Golgi apparatus completely and to stimulate Golgi–ER (endoplasmic reticulum) fusion in mammalian cells, akin to the well-characterized fungal toxin BFA (brefeldin A). It has also been reported that Exo2 does not affect the integrity of the TGN (trans-Golgi network), or the direct retrograde trafficking of the glycolipid-binding cholera toxin from the TGN to the ER lumen. We have examined the effects of BFA and Exo2, and found that both compounds are indistinguishable in their inhibition of anterograde transport and that both reagents significantly disrupt the morphology of the TGN in HeLa and in BS-C-1 cells. However, Exo2, unlike BFA, does not induce tubulation and merging of the TGN and endosomal compartments. Furthermore, and in contrast with its effects on cholera toxin, Exo2 significantly perturbs the delivery of Shiga toxin to the ER. Together, these results suggest that the likely target(s) of Exo2 operate at the level of the TGN, the Golgi and a subset of early endosomes, and thus Exo2 provides a more selective tool than BFA for examining membrane trafficking in mammalian cells
The Composition of Cosmic Rays at the Knee
The observation of a small change in spectral slope, or 'knee' in the fluxes
of cosmic rays near energies 10^15 eV has caused much speculation since its
discovery over 40 years ago. The origin of this feature remains unknown. A
small workshop to review some modern experimental measurements of this region
was held at the Adler Planetarium in Chicago, USA in June 2000. This paper
summarizes the results presented at this workshop and the discussion of their
interpretation in the context of hadronic models of atmospheric airshowers.Comment: 36 pages, 10 figure
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