611 research outputs found
Relative contributions of lattice distortion and orbital ordering to resonant x-ray scattering in manganites
We investigated the origin of the energy splitting observed in the resonant
x-ray scattering (RXS) in manganites. Using thin film samples with controlled
lattice parameters and orbital states at a fixed orbital filling, we estimated
that the contribution of the interatomic Coulomb interaction relative to the
Jahn-Teller mechanism is insignificant and at most 0.27. This indicates that
RXS probes mainly Jahn-Teller distortion in manganites.Comment: 8 pages, 4 figure
Relationship between charge stripe order and structural phase transitions in La1.875Ba0.125-xSrxCuO4
Distillation of Liquid Xenon to Remove Krypton
A high performance distillation system to remove krypton from xenon was
constructed, and a purity level of Kr/Xe = was
achieved. This development is crucial in facilitating high sensitivity low
background experiments such as the search for dark matter in the universe.Comment: 15 pages, 11 figure
Scintillation-only Based Pulse Shape Discrimination for Nuclear and Electron Recoils in Liquid Xenon
In a dedicated test setup at the Kamioka Observatory we studied pulse shape
discrimination (PSD) in liquid xenon (LXe) for dark matter searches. PSD in LXe
was based on the observation that scintillation light from electron events was
emitted over a longer period of time than that of nuclear recoil events, and
our method used a simple ratio of early to total scintillation light emission
in a single scintillation event. Requiring an efficiency of 50% for nuclear
recoil retention we reduced the electron background to 7.7\pm1.1(stat)\pm1.2
0.6(sys)\times10-2 at energies between 4.8 and 7.2 keVee and to
7.7\pm2.8(stat)\pm2.5 2.8(sys)\times10-3 at energies between 9.6 and 12 keVee
for a scintillation light yield of 20.9 p.e./keV. Further study was done by
masking some of that light to reduce this yield to 4.6 p.e./keV, the same
method results in an electron event reduction of 2.4\pm0.2(stat)\pm0.3
0.2(sys)\times10-1 for the lower of the energy regions above. We also observe
that in contrast to nuclear recoils the fluctuations in our early to total
ratio for electron events are larger than expected from statistical
fluctuations.Comment: 25 pages, 15 figure
Petrology of Two Itokawa Particles: Comparison with Equilibrated LL Chondrites
A strong link between Itokawa particles and LL chondrites was confirmed by preliminary examinations of Hayabusa particles [e.g., 1, 2]. Both poorly equilibrated and highly equilibrated particles have been found among the grains returned from Itokawa [1], and it is suggested that they correspond to LL4 and LL5-6, respectively. Here we report the petrography of two Itokawa particles and TEM study of one, and compare them to Antarctic LL chondrites with variable petrologic types (LL4-LL7) in order to understand the metamorphic history of asteroid Itokawa
Pure nematic state in iron-based superconductor
Lattice and electronic states of thin FeSe films on LaAlO substrates are
investigated in the vicinity of the nematic phase transition. No evidence of
structural phase transition is found by x-ray diffraction below K, while results obtained from resistivity measurement and angle-resolved
photoemission spectroscopy clearly show the appearance of a nematic state.
These results indicate formation of a pure nematic state in the iron-based
superconductor and provide conclusive evidence that the nematic state
originates from the electronic degrees of freedom. This pure nematicity in the
thin film implies difference in the electron-lattice interaction from bulk FeSe
crystals. FeSe films provide valuable playgrounds for observing the pure
response of "bare" electron systems free from the electron-lattice interaction,
and should make important contribution to investigate nematicity and its
relationship with superconductivity
DRAM-3 modulates autophagy and promotes cell survival in the absence of glucose
Macroautophagy is a membrane-trafficking process that delivers cytoplasmic constituents to lysosomes for degradation. The process operates under basal conditions as a mechanism to turnover damaged or misfolded proteins and organelles. As a result, it has a major role in preserving cellular integrity and viability. In addition to this basal function, macroautophagy can also be modulated in response to various forms of cellular stress, and the rate and cargoes of macroautophagy can be tailored to facilitate appropriate cellular responses in particular situations. The macroautophagy machinery is regulated by a group of evolutionarily conserved autophagy-related (ATG) proteins and by several other autophagy regulators, which either have tissue-restricted expression or operate in specific contexts. We report here the characterization of a novel autophagy regulator that we have termed DRAM-3 due to its significant homology to damage-regulated autophagy modulator (DRAM-1). DRAM-3 is expressed in a broad spectrum of normal tissues and tumor cells, but different from DRAM-1, DRAM-3 is not induced by p53 or DNA-damaging agents. Immunofluorescence studies revealed that DRAM-3 localizes to lysosomes/autolysosomes, endosomes and the plasma membrane, but not the endoplasmic reticulum, phagophores, autophagosomes or Golgi, indicating significant overlap with DRAM-1 localization and with organelles associated with macroautophagy. In this regard, we further proceed to show that DRAM-3 expression causes accumulation of autophagosomes under basal conditions and enhances autophagic flux. Reciprocally, CRISPR/Cas9-mediated disruption of DRAM-3 impairs autophagic flux confirming that DRAM-3 is a modulator of macroautophagy. As macroautophagy can be cytoprotective under starvation conditions, we also tested whether DRAM-3 could promote survival on nutrient deprivation. This revealed that DRAM-3 can repress cell death and promote long-term clonogenic survival of cells grown in the absence of glucose. Interestingly, however, this effect is macroautophagy-independent. In summary, these findings constitute the primary characterization of DRAM-3 as a modulator of both macroautophagy and cell survival under starvation conditions
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