Entanglement of single-photons and chiral phonons in atomically thin WSe2_2

Quantum entanglement is a fundamental phenomenon which, on the one hand, reveals deep connections between quantum mechanics, gravity and the space-time; on the other hand, has practical applications as a key resource in quantum information processing. While it is routinely achieved in photon-atom ensembles, entanglement involving the solid-state or macroscopic objects remains challenging albeit promising for both fundamental physics and technological applications. Here, we report entanglement between collective, chiral vibrations in two-dimensional (2D) WSe$_2$ host --- chiral phonons (CPs) --- and single-photons emitted from quantum dots (QDs) present in it. CPs which carry angular momentum were recently observed in WSe$_2$ and are a distinguishing feature of the underlying honeycomb lattice. The entanglement results from a "which-way" scattering process, involving an optical excitation in a QD and doubly-degenerate CPs, which takes place via two indistinguishable paths. Our unveiling of entanglement involving a macroscopic, collective excitation together with strong interaction between CPs and QDs in 2D materials opens up ways for phonon-driven entanglement of QDs and engineering chiral or non-reciprocal interactions at the single-photon level

Lagrangian Observations of the Middepth and Deep Velocity Fields of the Northeastern Atlantic Ocean

The circulation of the northeastern Atlantic Ocean at intermediate depths is characterized by watermass transformation processes that involve Iceland–Scotland Overflow Water (ISOW) from the northeast, Labrador Sea Water (LSW) from the west, and Mediterranean Water from the south. Field observations were carried out with 89 eddy-resolving floats (RAFOS and MARVOR types). The data coverage achieved is remarkably high and enables a comprehensive study of the eastern basins between Iceland and the Azores. The trajectories show typical pathways of the water masses involved and the role that the complex bottom topography plays in defining them. The ISOW paths tend to lean against the slopes of the Reykjanes Ridge and Rockall Plateau. Westward escapes through multiple gaps in the ridge are possible, superimposed on a sustained southward flow in the eastern basin along the Mid-Atlantic Ridge. LSW pathways leading to the eastern basins are subject to high variability in flow direction and eddy activity. In addition to a selection of characteristic trajectories, maps of the horizontal distributions of Lagrangian eddy kinetic energy and integral time scales are presented. These reveal distinct areas of intensified mixing in the Iceland Basin, as well as the sharp contrast between the subpolar and subtropical dynamics. A self-contained eddy detection scheme is applied to obtain statistics on individual eddy properties and their abundance. It is suggested that much of the intensified mixing can be related to cyclonic activity, particularly in the subpolar region

Warm-Start AlphaZero Self-Play Search Enhancements

Recently, AlphaZero has achieved landmark results in deep reinforcement learning, by providing a single self-play architecture that learned three different games at super human level. AlphaZero is a large and complicated system with many parameters, and success requires much compute power and fine-tuning. Reproducing results in other games is a challenge, and many researchers are looking for ways to improve results while reducing computational demands. AlphaZero's design is purely based on self-play and makes no use of labeled expert data ordomain specific enhancements; it is designed to learn from scratch. We propose a novel approach to deal with this cold-start problem by employing simple search enhancements at the beginning phase of self-play training, namely Rollout, Rapid Action Value Estimate (RAVE) and dynamically weighted combinations of these with the neural network, and Rolling Horizon Evolutionary Algorithms (RHEA). Our experiments indicate that most of these enhancements improve the performance of their baseline player in three different (small) board games, with especially RAVE based variants playing strongly

Electron quantum metamaterials in van der Waals heterostructures

In recent decades, scientists have developed the means to engineer synthetic periodic arrays with feature sizes below the wavelength of light. When such features are appropriately structured, electromagnetic radiation can be manipulated in unusual ways, resulting in optical metamaterials whose function is directly controlled through nanoscale structure. Nature, too, has adopted such techniques -- for example in the unique coloring of butterfly wings -- to manipulate photons as they propagate through nanoscale periodic assemblies. In this Perspective, we highlight the intriguing potential of designer sub-electron wavelength (as well as wavelength-scale) structuring of electronic matter, which affords a new range of synthetic quantum metamaterials with unconventional responses. Driven by experimental developments in stacking atomically layered heterostructures -- e.g., mechanical pick-up/transfer assembly -- atomic scale registrations and structures can be readily tuned over distances smaller than characteristic electronic length-scales (such as electron wavelength, screening length, and electron mean free path). Yet electronic metamaterials promise far richer categories of behavior than those found in conventional optical metamaterial technologies. This is because unlike photons that scarcely interact with each other, electrons in subwavelength structured metamaterials are charged, and strongly interact. As a result, an enormous variety of emergent phenomena can be expected, and radically new classes of interacting quantum metamaterials designed

Honokiol Arrests Cell Cycle, Induces Apoptosis, and Potentiates the Cytotoxic Effect of Gemcitabine in Human Pancreatic Cancer Cells

Survival rates for patients with pancreatic cancer are extremely poor due to its asymptomatic progression to advanced and metastatic stage for which current therapies remain largely ineffective. Therefore, novel therapeutic agents and treatment approaches are desired to improve the clinical outcome. In this study, we determined the effects of honokiol, a biologically active constituent of oriental medicinal herb Magnolia officinalis/grandiflora, on two pancreatic cancer cell lines, MiaPaCa and Panc1, alone and in combination with the standard chemotherapeutic drug, gemcitabine. Honokiol exerted growth inhibitory effects on both the pancreatic cancer cell lines by causing cell cycle arrest at G1 phase and induction of apoptosis. At the molecular level, honokiol markedly decreased the expression of cyclins (D1 and E) and cyclin-dependent kinases (Cdk2 and Cdk4), and caused an increase in Cdk inhibitors, p21 and p27. Furthermore, honokiol treatment led to augmentation of Bax/Bcl-2 and Bax/Bcl-xL ratios to favor apoptosis in pancreatic cancer cells. These changes were accompanied by enhanced cytoplasmic accumulation of NF-κB with a concomitant decrease in nuclear fraction and reduced transcriptional activity of NF-κB responsive promoter. This was associated with decreased phosphorylation of inhibitor of kappa B alpha (IκB-α) causing its stabilization and thus increased cellular levels. Importantly, honokiol also potentiated the cytotoxic effects of gemcitabine, in part, by restricting the gemcitabine-induced nuclear accumulation of NF-κB in the treated pancreatic cancer cell lines. Altogether, these findings demonstrate, for the first time, the growth inhibitory effects of honokiol in pancreatic cancer and indicate its potential usefulness as a novel natural agent in prevention and therapy

Mutation analysis of the CHK2 gene in breast carcinoma and other cancers

BACKGROUND: Mutations in the CHK2 gene at chromosome 22q12.1 have been reported in families with Li-Fraumeni syndrome. Chk2 is an effector kinase that is activated in response to DNA damage and is involved in cell-cycle pathways and p53 pathways. METHODS: We screened 139 breast tumors for loss of heterozygosity at chromosome 22q, using seven microsatellite markers, and screened 119 breast tumors with single-strand conformation polymorphism and DNA sequencing for mutations in the CHK2 gene. RESULTS: Seventy-four of 139 sporadic breast tumors (53%) show loss of heterozygosity with at least one marker. These samples and 45 tumors from individuals carrying the BRCA2 999del5 mutation were screened for mutations in the CHK2 gene. In addition to putative polymorphic regions in short mononucleotide repeats in a non-coding exon and intron 2, a germ line variant (T59K) in the first coding exon was detected. On screening 1172 cancer patients for the T59K sequence variant, it was detected in a total of four breast-cancer patients, two colon-cancer patients, one stomach-cancer patient and one ovary-cancer patient, but not in 452 healthy individuals. A tumor-specific 5' splice site mutation at site +3 in intron 8 (TTgt [a → c]atg) was also detected. CONCLUSION: We conclude that somatic CHK2 mutations are rare in breast cancer, but our results suggest a tumor suppressor function for CHK2 in a small proportion of breast tumors. Furthermore, our results suggest that the T59K CHK2 sequence variant is a low-penetrance allele with respect to tumor growth

SHARPIN Negatively Associates with TRAF2-Mediated NFκB Activation

NFκB is an inducible transcriptional factor controlled by two principal signaling cascades and plays pivotal roles in diverse physiological processes including inflammation, apoptosis, oncogenesis, immunity, and development. Activation of NFκB signaling was detected in skin of SHAPRIN-deficient mice and can be diminished by an NFκB inhibitor. However, in vitro studies demonstrated that SHARPIN activates NFκB signaling by forming a linear ubiquitin chain assembly complex with RNF31 (HOIP) and RBCK1 (HOIL1). The inconsistency between in vivo and in vitro findings about SHARPIN's function on NFκB activation could be partially due to SHARPIN's potential interactions with downstream molecules of NFκB pathway. In this study, 17 anti-flag immunoprecipitated proteins, including TRAF2, were identified by mass spectrum analysis among Sharpin-Flag transfected mouse fibroblasts, B lymphocytes, and BALB/c LN stroma 12 cells suggesting their interaction with SHARPIN. Interaction between SHARPIN and TRAF2 confirmed previous yeast two hybridization reports that SHARPIN was one TRAF2's partners. Furthermore, luciferase-based NFκB reporter assays demonstrated that SHARPIN negatively associates with NFκB activation, which can be partly compensated by over-expression of TRAF2. These data suggested that other than activating NFκB signaling by forming ubiquitin ligase complex with RNF31 and RBCK1, SHARPIN may also negatively associate with NFκB activation via interactions with other NFκB members, such as TRAF2

Azimuthal anisotropy and correlations at large transverse momenta in p+pp+p and Au+Au collisions at sNN\sqrt{s_{_{NN}}}= 200 GeV

Results on high transverse momentum charged particle emission with respect to the reaction plane are presented for Au+Au collisions at $\sqrt{s_{_{NN}}}$= 200 GeV. Two- and four-particle correlations results are presented as well as a comparison of azimuthal correlations in Au+Au collisions to those in $p+p$ at the same energy. Elliptic anisotropy, $v_2$, is found to reach its maximum at $p_t \sim 3$ GeV/c, then decrease slowly and remain significant up to $p_t\approx 7$ -- 10 GeV/c. Stronger suppression is found in the back-to-back high-$p_t$ particle correlations for particles emitted out-of-plane compared to those emitted in-plane. The centrality dependence of $v_2$ at intermediate $p_t$ is compared to simple models based on jet quenching.Comment: 4 figures. Published version as PRL 93, 252301 (2004