3,164 research outputs found
Spatial Interference: From Coherent To Incoherent
It is well known that direct observation of interference and diffraction
pattern in the intensity distribution requires a spatially coherent source.
Optical waves emitted from portions beyond the coherence area possess
statistically independent phases, and will degrade the interference pattern. In
this paper we show an optical interference experiment, which seems contrary to
our common knowledge, that the formation of the interference pattern is related
to a spatially incoherent light source. Our experimental scheme is very similar
to Gabor's original proposal of holography[1], just with an incoherent source
replacing the coherent one. In the statistical ensemble of the incoherent
source, each sample field produces a sample interference pattern between object
wave and reference wave. These patterns completely differ from each other due
to the fluctuation of the source field distribution. Surprisingly, the sum of a
great number of sample patterns exhibits explicitly an interference pattern,
which contains all the information of the object and is equivalent to a
hologram in the coherent light case. In this sense our approach would be
valuable in holography and other interference techniques for the case where
coherent source is unavailable, such as x-ray and electron sources.Comment: 8 pages, 5 figure
Fenofibrate Enhances the In Vitro Differentiation of Foxp3+ Regulatory T Cells in Mice
Foxp3+ regulatory T cells (Tregs) play a critical role in maintaining immune self-tolerance. Reduced number and activity of Tregs are usually found in autoimmune and inflammatory diseases, and enhancing the differentiation of Tregs may be a promising therapeutic strategy. Some reports suggested an anti-inflammatory and anti-autoimmune potential for fenofibrate, a hypolipidemic drug used worldwide, whose lipid effects are mediated by the activation of peroxisome proliferator-activated receptor α (PPARα). In the present paper, we found that fenofibrate dose-dependently increased transforming growth factor-β and interleukin-2-induced Treg differentiation in vitro, by 1.96-fold from 0 to 20 μM (12.59 ± 1.34% to 24.69 ± 3.03%, P < 0.05). Other PPARα activators, WY14643 (100 μM), gemfibrozil (50 μM), and bezafibrate (30 μM), could not enhance Treg differentiation. In addition, PPARα could not upregulate the promoter activity of the Treg-specific transcription factor Foxp3. Fenofibrate might exert its function by enhancing Smad3 phosphorylation, a critical signal in Treg differentiation, via Akt suppression. Our work reveals a new PPARα independent anti-inflammatory mechanism of fenofibrate in up-regulating mouse Treg differentiation
Sulphur isotopes toward Sagittarius B2 extended envelope in the Galactic Center
The isotopic ratios are good tools for probing the stellar nucleosynthesis
and chemical evolution. We performed high-sensitivity mapping observations of
the J=7-6 rotational transitions of OCS, OC34S, O13CS, and OC33S toward the
Galactic Center giant molecular cloud, Sagittarius B2 (Sgr B2) with IRAM 30m
telescope. Positions with optically thin and uncontaminated lines are chosen to
determine the sulfur isotope ratios. A 32S/34S ratio of 17.1\pm0.9 was derived
with OCS and OC34S lines, while 34S/33S ratio of 6.8\pm1.9 was derived directly
from integrated intensity ratio of OC34S and OC33S. With independent and
accurate measurements of 32S/34S ratio, our results confirm the termination of
the decreasing trend of 32S/34S ratios toward the Galactic Center, suggesting a
drop in the production of massive stars at the Galactic centre.Comment: 20 pages, 7 figures, accepted by PAS
Protein Phosphatase 2C of Toxoplasma Gondii Interacts with Human SSRP1 and Negatively Regulates Cell Apoptosis
International audienceBiographical notes of the first authors: GAO Xue Juan, female, born in 1980, PhD, assistant researcher, majoring in protein-protein interaction and signaling pathways; FENG Jun Xia, female, born in 1989, majoring in pathogenic molecular mechanism of pathogenic microorganisms. Abstract Objective The protozoan Toxoplasma gondii expresses large amounts of a 37 kDa Type 2C serine-threonine phosphatase, the so-called TgPP2C which has been suggested to contribute to parasite growth regulation. Ectopic expression in mammalian cells also indicated that the enzyme could regulate growth and survival. In this study, we aimed to investigate the interaction of TgPP2C with human SSRP1 (structure-specific recognition protein 1) and the effects of TgPP2C on cell viability. Methods The yeast two hybrid system, His-tag pull-down and co-immunoprecipitation assays were used to confirm the interaction of TgPP2C with SSRP1 and determine the binding domain on SSRP1. The evaluation of cell apoptosis was performed using cleaved caspase-3 antibody and Annexin-V/PI kit combined with flow cytometry. Results We identified human SSRP1 as an interacting partner of TgPP2C. The C-terminal region of SSRP1 including the amino acids 471 to 538 was specifically mapped as the region responsible for interaction with TgPP2C. The overexpression of TgPP2C down-regulated cell apoptosis and negatively regulated apoptosis induced by DRB, casein kinase II (CKII) inhibitor, through enhanced interaction with SSRP1. Conclusion TgPP2C may be a parasitic factor capable of promoting cell survival through interaction with the host protein SSRP1, thereby creating a favorable environment for parasite growth
Identification of Mesencephalic Astrocyte-Derived Neurotrophic Factor as a Novel Neuroprotective Factor for Retinal Ganglion Cells
Dense gas in local galaxies revealed by multiple tracers
We present 3 mm and 2 mm band simultaneously spectroscopic observations of
HCN 1-0, HCO 1-0, HNC 1-0, and CS 3-2 with the IRAM 30 meter telescope,
toward a sample of 70 sources as nearby galaxies with infrared luminosities
ranging from several 10 to more than 10. After
combining HCN 1-0, HCO 1-0 and HNC 1-0 data from literature with our
detections, relations between luminosities of dense gas tracers (HCN 1-0,
HCO 1-0 and HNC 1-0) and infrared luminosities are derived, with tight
linear correlations for all tracers. Luminosities of CS 3-2 with only our
observations also show tight linear correlation with infrared luminosities. No
systematic difference is found for tracing dense molecular gas among these
tracers. Star formation efficiencies for dense gas with different tracers also
do not show any trend along different infrared luminosities. Our study also
shows that HCN/HCO line ratio might not be a good indicator to diagnose
obscured AGN in galaxies.Comment: 25 pages, 5 figures, 3 tables. Accepted for publication in MNRA
Mapping Observations of Peptide-like molecules around Sagittarius B2
Peptide-like molecule, which has a close connection with the origin of life,
has been detected in universe. Mapping observations of HCONH and
CHCONH, two simplest peptide-like molecules, are performed towards
Sagittarius B2 (Sgr B2) complex with the IRAM 30m telescope. Seven transitions
of HCONH and five transitions of CHCONH are used in analysis. The
spatial distribution of excitation temperature and column density of HCONH
in the molecular envelope of Sgr B2 are obtained by the rotation diagrams.
Assuming the same excitation temperature as HCONH, the column densities of
CHCONH are also calculated. The results show that excitation
temperature ranges from 6 K to 46 K in the molecular envelope of Sgr B2. The
abundance ratio between HCONH and CHCONH are calculated to explore
the relationship among them, as well as HNCO mentioned in our pervious
research. The abundance ratio of CHCONH/HCONH varies from 10% to
20%, while that of HCONH/HNCO ranges from 1.5% to 10%. CHCONH is
enhanced with respect to HCONH in the northwest region of Sgr B2. One
transition of HCONH is detected toward 12 positions of Sgr B2, from
which a C/C ratio of 28.7 is obtained. A time-dependent chemical
model with a short duration of X-ray burst is used to explain the observed
abundances of HCONH and CHCONH, with the best fitting result at
T = 53-56 K. More chemical reactions are required to be included
into the model since the modeled abundance is lower than the observed one at
the observed T
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