Supervised Hamiltonian learning via efficient and robust quantum descent

Given the recent developments in quantum techniques, modeling the physical Hamiltonian of a target quantum many-body system is becoming an increasingly practical and vital research direction. Here, we propose an efficient quantum strategy that mingles maximum-likelihood-estimate state and supervised machine learning. Given the measurement outcomes, we optimize the target model Hamiltonian and density operator via a series of quantum descent, which we prove is negative semi-definite with respect to the negative-log-likelihood function. In addition to such optimization efficiency, supervised Hamiltonian learning respects the locality of a given quantum system, therefore, extends readily to larger systems. Compared with previous approaches, it also exhibits better accuracy and overall stability toward noises, fluctuations, and temperature ranges, which we demonstrate with various examples.Comment: 12 pages, 8figure

The "S" Curve Relationship between Export Diversity and Economic Size of Countries

The highly detailed international trade data among all countries in the world during 1971-2000 shows that the kinds of export goods and the logarithmic GDP (gross domestic production) of a country has an S-shaped relationship. This indicates all countries can be divided into three stages accordingly. First, the poor countries always export very few kinds of products as we expect. Second, once the economic size (GDP) of a country is beyond a threshold, its export diversity may increase dramatically. However, this is not the case for rich countries because a ceiling on the export diversity is observed when their GDPs are higher than another threshold. This pattern is very stable for different years although the concrete parameters of the fitting sigmoid functions may change with time. In addition, we also discussed other relationships such as import diversity with respect to logarithmic GDP, diversity of exporters with respect to the number of export goods etc., all of these relationships show S-shaped or power law patterns. Although this paper does not explain the origin of the S-shaped curve, it may provide a basic empirical fact and insights for economic diversity.Comment: 16 pages, 6 figure

Direct Torque Control System and Sensorless Technique of Permanent Magnet Synchronous Motor

AbstractThe direct torque control theory has achieved great success in the control of induction motors. However, in the DTC drive system of Permanent Magnet Synchronous Machine (PMSM) proposed a few years ago, there are many basic theoretical problems that must be clarified. This paper describes an investigation about the effect of the zero voltage space vectors in the DTC system of PMSM and points out that if using the zero voltage space vectors rationally, not only can the DTC system be driven successfully but also the torque ripple is reduced and the performance of the system is improved. This paper also studies the sensorless technique in the DTC system of PMSM and configures the DTC system of PMSM with sensorless technique including zero voltage space vectors. Numerical simulations and experimental tests have proved the theory correct. In the condition of sensorless, the DTC system of PMSM is wide-rangely speed adjusting, and the ratio of speed adjustment is 1:100

Resection of unresectable hepatocellular carcinoma after conversion therapy with apatinib and camrelizumab: a case report and literature review

Hepatocellular carcinoma is a rather common malignant tumor. Most patients with hepatocellular carcinoma receive their diagnosis at an advanced stage, at which surgical resection is no longer appropriate. A growing body of research has demonstrated the value of convention therapy for patients with intermediate-stage hepatocellular carcinoma, while specific application protocols and treatment guidelines are not well developed. Emerging clinical researches suggest that a tyrosine kinase inhibitor in combination with an immune checkpoint inhibitor is a reasonable strategy for unresectable hepatocellular carcinoma. However, there are relatively few reports on the efficacy of apatinib and camrelizumab in the treatment of hepatocellular carcinoma. We were able to successfully remove one patient’s hepatocellular carcinoma after 8 cycles of conversion therapy with apatinib (250 mg orally every day) and camrelizumab (200 mg intravenously every 2 weeks). The patient continued to receive the same dose of 16 cycles of apatinib and camrelizumab after hepatectomy. By the time of this study, the patient has completed 18 months of follow-up, and no tumor recurrence or metastasis was found in tumor markers and imaging examinations. Apatinib in combination with camrelizumab is an effective therapy for the treatment of advanced hepatocellular carcinoma, and surgical resection after this conversion therapy may provide patients with long-term oncological benefits. However, this requires more samples to validate the conclusion

Non-receptor tyrosine kinase Src is required for ischemia-stimulated neuronal cell proliferation via Raf/ERK/CREB activation in the dentate gyrus

<p>Abstract</p> <p>Background</p> <p>Neurogenesis in the adult mammalian hippocampus may contribute to repairing the brain after injury. However, Molecular mechanisms that regulate neuronal cell proliferation in the dentate gyrus (DG) following ischemic stroke insult are poorly understood. This study was designed to investigate the potential regulatory capacity of non-receptor tyrosine kinase Src on ischemia-stimulated cell proliferation in the adult DG and its underlying mechanism.</p> <p>Results</p> <p>Src kinase activated continuously in the DG 24 h and 72 h after transient global ischemia, while SU6656, the Src kinase inhibitor significantly decreased the number of bromodeoxyuridine (BrdU) labeling-positive cells of rats 7 days after cerebral ischemia in the DG, as well as down-regulated Raf phosphorylation at Tyr(340/341) site, and its down-stream signaling molecules ERK and CREB expression followed by 24 h and 72 h of reperfusion, suggesting a role of Src kinase as an enhancer on neuronal cell proliferation in the DG via modifying the Raf/ERK/CREB cascade. This hypothesis is supported by further findings that U0126, the ERK inhibitor, induced a reduction of adult hippocampal progenitor cells in DG after cerebral ischemia and down-regulated phospho-ERK and phospho-CREB expression, but no effect was detected on the activities of Src and Raf.</p> <p>Conclusion</p> <p>Src kinase increase numbers of newborn neuronal cells in the DG via the activation of Raf/ERK/CREB signaling cascade after cerebral ischemia.</p

STUDY ON OPTIMISATION OF EXTRACTION PROCESS OF TANSHINONE ⅡA AND ITS MECHANISM OF INDUCTION OF GASTRIC CANCER SGC7901 CELL APOPTOSIS

The objective of this paper was to investigate the extraction process of tanshinone ⅡA and its mechanism of induction of gastric cancer SGC7901 cell apoptosis. Extraction process of tanshinone ⅡA was optimised by orthogonal experimental method, and its effect on gastric cancer SGC7901 cell apoptosis was observed using MTT assay and electron microscopy. The optimum extraction process of tanshinone ⅡA was as follows: addition of a 10-fold amount of 80% ethanol, one-time extraction, and extraction time of 45 minutes. The study concluded that tanshinone ⅡA can induce apoptosis of gastric cancer SGC7901 cells

Measuring dynamic changes in the spatial pattern and connectivity of surface waters based on landscape and graph metrics: A case study of henan province in central china

An understanding of the scientific layout of surface water space is crucial for the sustainable development of human society and the ecological environment. The objective of this study was to use land-use/land-cover data to identify the spatiotemporal dynamic change processes and the influencing factors over the past three decades in Henan Province, central China. Multidisciplinary theories (landscape ecology and graph theory) and methods (GIS spatial analysis and SPSS correlation analysis) were used to quantify the dynamic changes in surface water pattern and connectivity. Our results revealed that the water area decreased significantly during the periods of 1990–2000 and 2010–2018 due to a decrease in tidal flats and linear waters, but increased significantly in 2000–2010 due to an increase in patchy waters. Human construction activities, socioeconomic development and topography were the key factors driving the dynamics of water pattern and connectivity. The use of graph metrics (node degree, betweenness centrality, and delta probability of connectivity) in combination with landscape metrics (Euclidean nearest-neighbor distance) can help establish the parameters of threshold distance between connected habitats, identify hubs and stepping stones, and determine the relatively important water patches that require priority protection or development