1,557 research outputs found
Deep two-photon microscopic imaging through brain tissue using the second singlet state from fluorescent agent chlorophyll α in spinach leaf
Abstract. Two-photon (2P) excitation of the second singlet (S2) state was studied to achieve deep optical microscopic imaging in brain tissue when both the excitation (800 nm) and emission (685 nm) wavelengths lie in the “tissue optical window” (650 to 950 nm). S2 state technique was used to investigate chlorophyll α (Chl α) fluorescence inside a spinach leaf under a thick layer of freshly sliced rat brain tissue in combination with 2P microscopic imaging. Strong emission at the peak wavelength of 685 nm under the 2P S2 state of Chl α enabled the imaging depth up to 450 μm through rat brain tissue
Certification of Reference Materials of Soya Seed Powder with different Mass Fractions of Genetically Modified 305423 Soya, Certified Reference Materials ERM-BF426 (ERM-BF426a, ERM-BF426b, ERM-BF426c, ERM-BF426d)
This report describes the processing and certification of four soya seed powder Certified Reference Materials (CRMs) containing different mass fractions of genetically modified (GM) 305423 soya (ERM-BF426a, b, c, d). The materials were processed and certified in 2007 by the European Commission, Directorate General Joint Research Centre, Institute for Reference Materials and Measurements (IRMM, Geel, Belgium), according to the principles of ISO Guide 34. The CRMs are intended to be used for quality control or calibration of methods for the quantification of the 305423 soya mass fraction in food and feed. The CRMs are available in glass bottles containing 1 g of dried soya powder closed under argon atmosphere. The minimum amount of sample to be used per analysis is 200 mg.
The four CRMs have been accepted as European Reference Material (ERM) after peer evaluation by the partners of the European Reference Materials consortium.JRC.D.2-Reference material
Certification of Reference Materials of Maize Seed Powder containing Genetically Modified MON 810 Maize: Certified Reference Materials ERM®-BF413k (ERM®-BF413ak, ERM®-BF413ck, ERM®-BF413ek, ERM®-BF413gk)
The report describes the processing and certification of four maize seed powder Certified Reference Materials (CRMs) containing different mass fractions of genetically modified (GM) MON 810 maize (ERM-BF413ak, ck, ek, gk). The materials were processed and certified in 2007/2008 by the European Commission, Joint Research Centre, Institute for Reference Materials and Measurements IRMM, Geel, Belgium), according to the principles of ISO Guide 34. The four CRMs belonging to the ERM-BF413k series replace the earlier produced series ERM-BF413 which is exhausted. The four CRMs have been accepted as European Reference Material (ERM®) after peer evaluation by the partners of the European Reference Materials consortium.JRC.D.2-Reference material
Steady state entanglement of two coupled qubits
The maximum entanglement between two coupled qubits in the steady state under
two independent incoherent sources of excitation is reported. Asymmetric
configurations where one qubit is excited while the other one dissipates the
excitation are optimal for entanglement, reaching values three times larger
than with thermal sources. The reason is the purification of the steady state
mixture (that includes a Bell state) thanks to the saturation of the pumped
qubit. Photon antibunching between the cross emission of the qubits can be used
to experimentally evidence the large degrees of entanglement.Comment: 7 pages, 5 figure
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Deacetylation of p53 induces autophagy by suppressing Bmf expression
Interferon γ (IFN-γ)–induced cell death is mediated by the BH3-only domain protein, Bik, in a p53-independent manner. However, the effect of IFN-γ on p53 and how this affects autophagy have not been reported. The present study demonstrates that IFN-γ down-regulated expression of the BH3 domain-only protein, Bmf, in human and mouse airway epithelial cells in a p53-dependent manner. p53 also suppressed Bmf expression in response to other cell death–stimulating agents, including ultraviolet radiation and histone deacetylase inhibitors. IFN-γ did not affect Bmf messenger RNA half-life but increased nuclear p53 levels and the interaction of p53 with the Bmf promoter. IFN-γ–induced interaction of HDAC1 and p53 resulted in the deacetylation of p53 and suppression of Bmf expression independent of p53’s proline-rich domain. Suppression of Bmf facilitated IFN-γ–induced autophagy by reducing the interaction of Beclin-1 and Bcl-2. Furthermore, autophagy was prominent in cultured bmf−/− but not in bmf+/+ cells. Collectively, these observations show that deacetylation of p53 suppresses Bmf expression and facilitates autophagy
Distinct Mechanisms for Induction and Tolerance Regulate the Immediate Early Genes Encoding Interleukin 1β and Tumor Necrosis Factor α
Interleukin-1β and Tumor Necrosis Factor α play related, but distinct, roles in immunity and disease. Our study revealed major mechanistic distinctions in the Toll-like receptor (TLR) signaling-dependent induction for the rapidly expressed genes (IL1B and TNF) coding for these two cytokines. Prior to induction, TNF exhibited pre-bound TATA Binding Protein (TBP) and paused RNA Polymerase II (Pol II), hallmarks of poised immediate-early (IE) genes. In contrast, unstimulated IL1B displayed very low levels of both TBP and paused Pol II, requiring the lineage-specific Spi-1/PU.1 (Spi1) transcription factor as an anchor for induction-dependent interaction with two TLR-activated transcription factors, C/EBPβ and NF-κB. Activation and DNA binding of these two pre-expressed factors resulted in de novo recruitment of TBP and Pol II to IL1B in concert with a permissive state for elongation mediated by the recruitment of elongation factor P-TEFb. This Spi1-dependent mechanism for IL1B transcription, which is unique for a rapidly-induced/poised IE gene, was more dependent upon P-TEFb than was the case for the TNF gene. Furthermore, the dependence on phosphoinositide 3-kinase for P-TEFb recruitment to IL1B paralleled a greater sensitivity to the metabolic state of the cell and a lower sensitivity to the phenomenon of endotoxin tolerance than was evident for TNF. Such differences in induction mechanisms argue against the prevailing paradigm that all IE genes possess paused Pol II and may further delineate the specific roles played by each of these rapidly expressed immune modulators. © 2013 Adamik et al
Surveying Nearby Brown Dwarfs with HGCA: Direct Imaging Discovery of a Faint, High-Mass Brown Dwarf Orbiting HD 176535 A
Brown dwarfs with well-measured masses, ages and luminosities provide direct
benchmark tests of substellar formation and evolutionary models. We report the
first results from a direct imaging survey aiming to find and characterize
substellar companions to nearby accelerating stars with the assistance of the
Hipparcos-Gaia Catalog of Accelerations (HGCA). In this paper, we present a
joint high-contrast imaging and astrometric discovery of a substellar companion
to HD 176535 A, a K3.5V main-sequence star aged approximately
Gyrs at a distance of pc. In advance of
our high-contrast imaging observations, we combined precision HARPS RVs and
HGCA astrometry to predict the potential companion's location and mass. We
thereafter acquired two nights of KeckAO/NIRC2 direct imaging observations in
the band, which revealed a companion with a contrast of mag at a projected separation of 0.\!\!''35
(13 AU) from the host star. We revise our orbital fit by incorporating
our dual-epoch relative astrometry using the open-source MCMC orbit fitting
code . HD 176535 B is a new benchmark dwarf useful for constraining
the evolutionary and atmospheric models of high-mass brown dwarfs. We found a
luminosity of and a model-dependent
effective temperature of K for HD 176535 B. Our dynamical mass
suggests that some substellar evolutionary models may be underestimating
luminosity for high-mass T dwarfs. Given its angular separation and luminosity,
HD 176535 B would make a promising candidate for Aperture Masking
Interferometry with JWST and GRAVITY/KPIC, and further spectroscopic
characterization with instruments like the CHARIS/SCExAO/Subaru integral field
spectrograph
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