Observation of higher-order topological states on a quantum computer

Programmable quantum simulators such as superconducting quantum processors and ultracold atomic lattices represent rapidly developing emergent technology that may one day qualitatively outperform existing classical computers. Yet, apart from a few breakthroughs, the range of viable computational applications with current-day noisy intermediate-scale quantum (NISQ) devices is still significantly limited by gate errors, quantum decoherence, and the number of high-quality qubits. In this work, we develop an approach that places NISQ hardware as a particularly suitable platform for simulating multi-dimensional condensed matter systems, including lattices beyond three dimensions which are difficult to realize or probe in other settings. By fully exploiting the exponentially large Hilbert space of a quantum chain, we encoded a high-dimensional model in terms of non-local many-body interactions that can further be systematically transcribed into quantum gates. We demonstrate the power of our approach by realizing, on IBM transmon-based quantum computers, higher-order topological states in up to four dimensions, which are exotic phases that have never been realized in any quantum setting. With the aid of in-house circuit compression and error mitigation techniques, we measured the topological state dynamics and their protected mid-gap spectra to a high degree of accuracy, as benchmarked by reference exact diagonalization data. The time and memory needed with our approach scale favorably with system size and dimensionality compared to exact diagonalization on classical computers.Comment: 21 pages, 8 figures in main text; 4 pages, 2 tables in supplementary informatio

Prediction and identification of synergistic compound combinations against pancreatic cancer cells.

Resistance to current therapies is common for pancreatic cancer and hence novel treatment options are urgently needed. In this work, we developed and validated a computational method to select synergistic compound combinations based on transcriptomic profiles from both the disease and compound side, combined with a pathway scoring system, which was then validated prospectively by testing 30 compounds (and their combinations) on PANC-1 cells. Some compounds selected as single agents showed lower GI50 values than the standard of care, gemcitabine. Compounds suggested as combination agents with standard therapy gemcitabine based on the best performing scoring system showed on average 2.82-5.18 times higher synergies compared to compounds that were predicted to be active as single agents. Examples of highly synergistic in vitro validated compound pairs include gemcitabine combined with Entinostat, thioridazine, loperamide, scriptaid and Saracatinib. Hence, the computational approach presented here was able to identify synergistic compound combinations against pancreatic cancer cells

Stabilizing multiple topological fermions on a quantum computer

AbstractIn classical and single-particle settings, non-trivial band topology always gives rise to robust boundary modes. For quantum many-body systems, however, multiple topological fermions are not always able to coexist, since Pauli exclusion prevents additional fermions from occupying the limited number of available topological modes. In this work, we show, through IBM quantum computers, how one can robustly stabilize more fermions than the number of topological modes through specially designed 2-fermion interactions. Our demonstration hinges on the realization of BDI- and D-class topological Hamiltonians on transmon-based quantum hardware, and relied on a tensor network-aided circuit recompilation approach. We also achieved the full reconstruction of multiple-fermion topological band structures through iterative quantum phase estimation (IQPE). All in all, our work showcases how advances in quantum algorithm implementation enable noisy intermediate-scale quantum (NISQ) devices to be exploited for topological stabilization beyond the context of single-particle topological invariants.</jats:p

A Detailed Study of Spitzer-IRAC Emission in Herbig-Haro Objects (I): Morphology and Flux Ratios of Shocked Emission

We present a detailed analysis of Spitzer-IRAC images obtained toward six Herbig-Haro objects (HH 54/211/212, L 1157/1448, BHR 71). Our analysis includes: (1) comparisons in morphology between the four IRAC bands (3.6, 4.5, 5.8 and 8.0 um), and H2 1-0 S(1) at 2.12 um for three out of six objects; (2) measurements of spectral energy distributions (SEDs) at selected positions; and (3) comparisons of these results with calculations of thermal H2 emission at LTE (207 lines in four bands) and non-LTE (32-45 lines, depending on particle for collisions). We show that the morphologies observed at 3.6 and 4.5 um are similar to each other, and to H2 1-0 S(1). This is well explained by thermal H2 emission at non-LTE if the dissociation rate is significantly larger than 0.002-0.02, allowing thermal collisions to be dominated by atomic hydrogen. In contrast, the 5.8 and 8.0 um emission shows different morphologies from the others in some regions. This emission appears to be more enhanced at the wakes in bow shocks, or less enhanced in patchy structures in the jet. These tendencies are explained by the fact that thermal H2 emission in the 5.8 and 8.0 um band is enhanced in regions at lower densities and temperatures. Throughout, the observed similarities and differences in morphology between four bands and 1-0 S(1) are well explained by thermal H2 emission. The observed SEDs are categorized into:- (A) those in which the flux monotonically increases with wavelength; and (B) those with excess emission at 4.5-um. The type-A SEDs are explained by thermal H2 emission, in particular with simple shock models with a power-law cooling function. Our calculations suggest that the type-B SEDs require extra contaminating emission in the 4.5-um band. The CO vibrational emission is the most promising candidate, and the other contaminants discussed to date are not likely to explain the observed SEDs.Comment: 35 pages, 21 figures, 6 tables, accepted by Astrophysical Journa

A solvable model for the diffusion and reaction of neurotransmitters in a synaptic junction

<p>Abstract</p> <p>Background</p> <p>The diffusion and reaction of the transmitter acetylcholine in neuromuscular junctions and the diffusion and binding of Ca²⁺in the dyadic clefts of ventricular myocytes have been extensively modeled by Monte Carlo simulations and by finite-difference and finite-element solutions. However, an analytical solution that can serve as a benchmark for testing these numerical methods has been lacking.</p> <p>Result</p> <p>Here we present an analytical solution to a model for the diffusion and reaction of acetylcholine in a neuromuscular junction and for the diffusion and binding of Ca²⁺in a dyadic cleft. Our model is similar to those previously solved numerically and our results are also qualitatively similar.</p> <p>Conclusion</p> <p>The analytical solution provides a unique benchmark for testing numerical methods and potentially provides a new avenue for modeling biochemical transport.</p

Dengue Virus Surveillance for Early Warning, Singapore

In Singapore, after a major outbreak of dengue in 2005, another outbreak occurred in 2007. Laboratory-based surveillance detected a switch from dengue virus serotype 1 (DENV-1) to DENV-2. Phylogenetic analysis showed a clade replacement within DENV-2 cosmopolitan genotype, which accompanied the predominant serotype switch, and cocirculation of multiple genotypes of DENV-3

Synthesis of novel derivatives of murrayafoline A and their inhibitory effect on LPS-stimulated production of pro-inflammatory cytokines in bone marrow-derived dendritic cells

Cu(I)-catalyzed Huisgen–Meldal–Sharpless type dipolar ‘click’ reactions between azido-tetrathiafulvalene derivatives and ethynylferrocene yield the first examples of ferrocenyl-1,2,3-triazolyl-tetrathiafulvalene assemblies (4a, 4b). The electrochemical behavior of 4a and 4b, which integrate two distinctive redox probes, has been investigated, and their binding ability for various transition-metal cations has been studied by cyclic voltammetry. The contribution of the triazolyl ring in the guest binding process is illustrated by the specific electrochemical recognition of Zn2+ by receptor 4b

Cellular direct conversion by cell penetrable OCT4-30Kc19 protein and BMP4 growth factor

Background : The number of patients suffering from osteoporosis is increasing as the elderly population increases. The demand for investigating bone regeneration strategies naturally arises. One of the approaches to induce bone regeneration is somatic cell transdifferentiation. Among the transcriptional regulators for transdifferentiation, octamer-binding transcription factor 4 (OCT4) is famous for its role in the regulation of pluripotency of stem cells. Bone morphogenetic protein 4 (BMP4) is another factor that is known to have a significant role in osteogenic differentiation. Previous studies have achieved transdifferentiation of cells into osteoblasts using viral and plasmid deliveries of these factors. Although these methods are efficient, viral and plasmid transfection have safety issues such as permanent gene incorporations and bacterial DNA insertions. Herein, we developed a cell penetrating protein-based strategy to induce transdifferentiation of endothelial cells into osteoblasts via nuclear delivery of OCT4 recombinant protein combined with the BMP4 treatment. For the nuclear delivery of OCT4 protein, we fused the protein with 30Kc19, a cell-penetrating and protein stabilizing protein derived from a silkworm hemolymph of Bombyx mori with low cytotoxic properties. This study proposes a promising cell-based therapy without any safety issues that existing transdifferentiation approaches had. Methods : OCT4-30Kc19 protein with high penetrating activities and stability was synthesized for a protein-based osteogenic transdifferentiation system. Cells were treated with OCT4-30Kc19 and BMP4 to evaluate their cellular penetrating activity, cytotoxicity, osteogenic and angiogenic potentials in vitro. The osteogenic potential of 3D cell spheroids was also analyzed. In addition, in vivo cell delivery into subcutaneous tissue and cranial defect model was performed. Results : OCT4-30Kc19 protein was produced in a soluble and stable form. OCT4-30Kc19 efficiently penetrated cells and were localized in intracellular compartments and the nucleus. Cells delivered with OCT4-30Kc19 protein combined with BMP4 showed increased osteogenesis, both in 2D and 3D culture, and showed increased angiogenesis capacity in vitro. Results from in vivo subcutaneous tissue delivery of cell-seeded scaffolds confirmed enhanced osteogenic properties of transdifferentiated HUVECs via treatment with both OCT4-30Kc19 and BMP4. In addition, in vivo mouse cranial defect experiment demonstrated successful bone regeneration of HUVECs pretreated with both OCT4-30Kc19 and BMP4. Conclusions : Using a protein-based transdifferentiation method allows an alternative approach without utilizing any genetic modification strategies, thus providing a possibility for safer use of cell-based therapies in clinical applications.This work was fnancially supported by the Ministry of Science and ICT (NRF2021R1A2C2008821). The Institute of Engineering Research at Seoul National University provided research facilities for this work

Takayasu's Arteritis Treated by Percutaneous Transluminal Angioplasty with Stenting in the Descending Aorta

A 17-yr-old young woman was referred to our hospital with a 2-yr history of claudication of the lower extremities and severe arterial hypertension. Physical examination revealed significantly different blood pressures between both arms (160/92 and 180/95 mmHg) and legs (92/61 and 82/57 mmHg). The hematological and biochemical values were within their normal ranges, except for the increased erythrocyte sedimentation rate (83 mm/hr) and C-reactive protein (6.19 mg/L). On 3-dimensional computed tomographic angiography, the ascending aorta, the aortic arch and its branches, and the thoracic and, descending aorta, but not the renal artery, were shown to be stenotic. The diagnosis of type IIb Takayasu's arteritis was made according to the new angiographic classification of Takayasu's arteritis, Takyasu conference 1994. Percutaneous transluminal angioplasty with stenting was performed on the thoracic and abdominal aorta. After the interventional procedures, the upper extremity blood pressure improved from 162/101 mmHg to 132/85 mmHg, respectively. She has been free of claudication and there have been no cardiac events during 2-yr of clinical follow-up