ENGINEERING RADIATIVE TRANSITIONS OF ALKALI-RARE GAS COLLISION PAIRS

Optical amplifiers that rely on free-free molecular transition for both pumping and amplification will be introduced. A gaseous medium comprised of Cs vapor and Ar is photoexcited through a free-free molecular transition, B $^{2}$$\Sigma$$_{1/2}^{+}$ $\leftarrow$ X $^{2}$$\Sigma$$_{1/2}^{+}$, with a pulse duration of 8 ns. The gain medium is characterized by scanning the probe wavelength and changing the time delay between the pump and probe pulses. It will be shown that the large bandwidth ($>$150 GHz) and reduced lifetime ($\sim$5 ns) make the amplifiers more suitable for high power IR sources. The optical-to-optical efficiency exceeds 28\% in a single pass amplification. The circular polarization of the optical pump increases the efficiency by 20\%. Furthermore, the weak atomic interaction was identified in the gain spectrum of a Cs-Xe gas mixture by implementing the pump-probe method and compared to the simulation based on the Franck-Condon principle. The spectral feature, also known as the red satellite, had been hard to be resolved experimentally because of the wing structure of A$^{2}$$\Pi$$_{3/2}^{+}$ $\leftarrow$ X $^{2}$$\Sigma$$_{1/2}^{+}$ transition. In the simulation, the Franck-Condon overlap integral develops in the region as the phases of the wavefunctions are stationary to each other, which shows that even a shallow feature in the potential curve can contribute the resulting spectrum significantly. This technique can be utilized in precise atomic spectroscopy

Extinction of 10.6 μm laser radiation by free electrons in an argon discharge at atmospheric pressure

Experiments will be described in which the extinction of 10.6 μm photons by free electrons in a single filamentary discharge is studied. The extinction ranges from 3 to 10 percent over a path length of 1 cm, depending on the argon flow rate. The spatio-temporally averaged electron density in the filament is more than 10^15 cm^(-3), as determined by Stark broadening of the hydrogen alpha (656.28 nm) and 4p'[1/2]-4s[3/2]^0 argon I (696.54 nm) lines. Experiments indicate that the observed extinction of 10.6 μm is attributable to a combination of inverse bremsstrahlung and a negative lens effect, and the results will be compared to theoretical calculations based on Boltzmann's equation. The potential application of such high electron density plasmas to studies of fundamental plasma phenomena, as well as optical applications, will be discussed

Metformin Decreases 2-HG Production through the MYC-PHGDH Pathway in Suppressing Breast Cancer Cell Proliferation

The biguanide drug metformin has been widely used for the treatment of type 2 diabetes, and there is evidence supporting the anticancer effect of metformin despite some controversy. Here, we report the growth inhibitory activity of metformin in the breast cancer (MCF-7) cells, both in vitro and in vivo, and the associated metabolic changes. In particular, a decrease in a well-known oncometabolite 2-hydroxyglutarate (2-HG) was discovered by a metabolomics approach. The decrease in 2-HG by metformin was accompanied by the reduction in histone methylation, consistent with the known tumorigenic mechanism of 2-HG. The relevance of 2-HG inhibition in breast cancer was also supported by a higher level of 2-HG in human breast cancer tissues. Genetic knockdown of PHGDH identified the PHGDH pathway as the producer of 2-HG in the MCF-7 cells that do not carry isocitrate dehydrogenase 1 and 2 (IDH1/IDH2) mutations, the conventional producer of 2-HG. We also showed that metformin's inhibitory effect on the PHGDH-2HG axis may occur through the regulation of the AMPK-MYC pathway. Overall, our results provide an explanation for the coherent pathway from complex I inhibition to epigenetic changes for metformin's anticancer effect.Peer reviewe

Learning Debiased Classifier with Biased Committee

Neural networks are prone to be biased towards spurious correlations between classes and latent attributes exhibited in a major portion of training data, which ruins their generalization capability. We propose a new method for training debiased classifiers with no spurious attribute label. The key idea is to employ a committee of classifiers as an auxiliary module that identifies bias-conflicting data, i.e., data without spurious correlation, and assigns large weights to them when training the main classifier. The committee is learned as a bootstrapped ensemble so that a majority of its classifiers are biased as well as being diverse, and intentionally fail to predict classes of bias-conflicting data accordingly. The consensus within the committee on prediction difficulty thus provides a reliable cue for identifying and weighting bias-conflicting data. Moreover, the committee is also trained with knowledge transferred from the main classifier so that it gradually becomes debiased along with the main classifier and emphasizes more difficult data as training progresses. On five real-world datasets, our method outperforms prior arts using no spurious attribute label like ours and even surpasses those relying on bias labels occasionally.Comment: Conference on Neural Information Processing Systems (NeurIPS), New Orleans, 202

A microporous metal-organic framework constructed from a 1D column made of linear trinuclear manganese secondary building units

A metal-organic framework (MOF) was prepared based on a 1D column made of a linear trinuclear manganese cluster as a secondary building unit (SBU), where the SBU is connected to two adjacent SBUs by carboxylates to form a 1D column and the column is further connected to four adjacent 1D columns via the SBUs to form a microporous MOF of pcu network topology.close7

Multi-dimensional histone methylations for coordinated regulation of gene expression under hypoxia

Hypoxia increases both active and repressive histone methylation levels via decreased activity of histone demethylases. However, how such increases coordinately regulate induction or repression of hypoxia-responsive genes is largely unknown. Here, we profiled active and repressive histone tri-methylations (H3K4me3, H3K9me3, and H3K27me3) and analyzed gene expression profiles in human adipocyte-derived stem cells under hypoxia. We identified differentially expressed genes (DEGs) and differentially methylated genes (DMGs) by hypoxia and clustered the DEGs and DMGs into four major groups. We found that each group of DEGs was predominantly associated with alterations in only one type among the three histone tri-methylations. Moreover, the four groups of DEGs were associated with different TFs and localization patterns of their predominant types of H3K4me3, H3K9me3 and H3K27me3. Our results suggest that the association of altered gene expression with prominent single-type histone tri-methylations characterized by different localization patterns and with different sets of TFs contributes to regulation of particular sets of genes, which can serve as a model for coordinated epigenetic regulation of gene expression under hypoxia.111Ysciescopu

Security Clustering: A Network-wide Secure Computing Mechanism in Pervasive Computing

Abstract. In this paper, we introduce a new security paradigm, called security clustering, for pervasive computing environment that enables network-wide defend against increasing evolutionary attacks on the heterogeneous network and hosts. Security clustering make use of dynamic security context exchange between cluster members and distributed information sharing to achieve scalable and efficient cooperation

High-efficiency, high-speed, and low-noise photonic quantum memory

We present a demonstration of simultaneous high-efficiency, high-speed, and low-noise operation of a photonic quantum memory. By leveraging controllable collisional dephasing in a neutral barium atomic vapor, we demonstrate a significant improvement in memory efficiency and bandwidth over existing techniques. We achieve greater than 95% storage efficiency and 26% total efficiency of 880 GHz bandwidth photons, with $\mathcal{O}(10^{-5})$ noise photons per retrieved pulse. These ultrabroad bandwidths enable rapid quantum information processing and contribute to the development of practical quantum memories with potential applications in quantum communication, computation, and networking

Rhus verniciflua Stokes against Advanced Cancer: A Perspective from the Korean Integrative Cancer Center

Active anticancer molecules have been searched from natural products; many drugs were developed from either natural products or their derivatives following the conventional pharmaceutical paradigm of drug discovery. However, the advances in the knowledge of cancer biology have led to personalized medicine using molecular-targeted agents which create new paradigm. Clinical benefit is dependent on individual biomarker and overall survival is prolonged through cytostatic rather than cytotoxic effects to cancer cell. Therefore, a different approach is needed from the single lead compound screening model based on cytotoxicity. In our experience, the Rhus verniciflua stoke (RVS) extract traditionally used for cancer treatment is beneficial to some advanced cancer patients though it is herbal extract not single compound, and low cytotoxic in vitro. The standardized RVS extract's action mechanisms as well as clinical outcomes are reviewed here. We hope that these preliminary results would stimulate different investigation in natural products from conventional chemicals