1,870 research outputs found

    Lifshitz Scaling Effects on Holographic Superconductors

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    Via numerical and analytical methods, the effects of the Lifshitz dynamical exponent zz on holographic superconductors are studied in some detail, including ss wave and pp wave models. Working in the probe limit, we find that the behaviors of holographic models indeed depend on concrete value of zz. We obtain the condensation and conductivity in both Lifshitz black hole and soliton backgrounds with general zz. For both ss wave and pp wave models in the black hole backgrounds, as zz increases, the phase transition becomes more difficult and the growth of conductivity is suppressed. For the Lifshitz soliton backgrounds, when zz increases (z=1, 2, 3z=1,~2,~3), the critical chemical potential decreases in the ss wave cases but increases in the pp wave cases. For pp wave models in both Lifshitz black hole and soliton backgrounds, the anisotropy between the AC conductivity in different spatial directions is suppressed when zz increases. The analytical results uphold the numerical results.Comment: Typos corrected; Footnote added; References added; To be published in Nuclear Physics

    Methological quality of systematic reviews and meta-analyses on acupuncture for stroke: a review of review

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    Objective: To assess the methodological quality of systematic reviews and meta-analyses regarding acupuncture intervention for stroke and the primary studies within them. Methods: Two researchers searched PubMed, Cumulative index to Nursing and Allied Health Literature, Embase, ISI Web of Knowledge, Cochrane, Allied and Complementary Medicine, Ovid Medline, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, Wanfang and Traditional Chinese Medical Database to identify systematic reviews and meta-analyses about acupuncture for stroke published from the inception to December 2016. Review characteristics and the criteria for assessing the primary studies within reviews were extracted. The methodological quality of the reviews was assessed using adapted Oxman and Guyatt Scale. The methodological quality of primary studies was also assessed. Results: Thirty-two eligible reviews were identified, 15 in English and 17 in Chinese. The English reviews were scored higher than the Chinese reviews (P=0.025), especially in criteria for avoiding bias and the scope of search. All reviews used the quality criteria to evaluate the methodological quality of primary studies, but some criteria were not comprehensive. The primary studies, in particular the Chinese reviews, had problems with randomization, allocation concealment, blinding, dropouts and withdrawals, intent-to-treat analysis and adverse events. Conclusions: Important methodological flaws were found in Chinese systematic reviews and primary studies. It was necessary to improve the methodological quality and reporting quality of both the systematic reviews published in China and primary studies on acupuncture for stroke

    Ba-enhanced dwarf and subgiant stars in the LAMOST Galactic surveys

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    Ba-enhanced stars are interesting probes of stellar astrophysics and Galactic formation history. In this work, we investigate the chemistry and kinematics for a large sample of Ba-enhanced ([Ba/Fe]>>1.0) dwarf and subgiant stars with 5000<Teff<67005000 < T_{\rm eff }< 6700\,K from LAMOST. We find that both stellar internal evolution process and external mass exchange due to binary evolution are responsible for the origins of the Ba-enhancement of our sample stars. About one third of them exhibit C and N enhancement and ultraviolet brightness excess, indicating they are products of binary evolution. The remaining Ba-enhanced stars with normal C and N abundances are mostly warm stars with Teff>6000T_{\rm eff} > 6000\,K. They are likely consequences of stellar internal elemental transport processes, but they show very different elemental patterns to the hotter Am/Fm stars. Our results reveal a substantially lack of high-[α\alpha/Fe] Ba-enhanced stars in the [Fe/H]--[α\alpha/Fe] plane, which we dub as a {\em high-α\alpha desert}. We suggest it is due to a lower efficiency for producing Ba-enhanced stars by low-mass AGB progenitors in binary systems. Our results call for detailed modellings for these Ba-enhanced stellar peculiars, in the context of both stellar internal elemental transport and external mass accretion.Comment: 20 pages, 17 figures. Accepted for publication in Ap

    Biomimetic Metal-Organic Nanoparticles Prepared with a 3D-Printed Microfluidic Device as a Novel Formulation for Disulfiram-Based Therapy Against Breast Cancer

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    Disulfiram (DSF) is currently tested in several clinical trials for cancer treatment in combination with cop-per (Cu) ions. Usually, DSF and Cu are administered in two separate formulations. In the body, DSF andCu ions form diethyldithiocarbamate copper complex [Cu(DDC)2] which has potent antitumor activities.However, the “two formulation” approach often achieved low Cu(DDC)2 concentration at tumor regions and resulted in compromised anticancer efficacy. Therefore, preformed Cu(DDC)2 complex administered in a single formulation will have better anticancer efficacy. However, the poor aqueous solubility of Cu(DDC)2 is a significant challenge for its clinical use. In this work, a biomimetic nanoparticle formulation of Cu(DDC)2 was produced with a novel SMILE (Stabilized Metal Ion Ligand complex) method developed in our laboratory to address the drug delivery challenges. The Metal-organic Nanoparticle (MON) is composed of Cu(DDC)2 metal-organic complex core and surface decorated bovine serum albumin (BSA). Importantly, we designed a 3D-printed microfluidic device to further improve the fabrication of BSA/Cu(DDC)2 MONs. This method could precisely control the MON preparation process and also has great potential for large scale production of Cu(DDC)2 MON formulations. We also used a computational modeling approach to simulate the MON formation process in the microfluidic device. The optimized BSA/Cu(DDC)2 MONs demonstrated good physicochemical properties. The MONs also showed potent antitumor activities in the breast cancer cell monolayers as well as the 3D-cultured tumor spheroids. The BSA/Cu(DDC)2 MONs also effectively inhibited the growth of tumors in an orthotopic 4T1 breast tumor model. This current study provided a novel method to prepare a biomimetic MON formulation for DSF/Cu cancer therapy .© 2019 Elsevier Ltd. All rights reserved

    Explainable Recommendation: Theory and Applications

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    Although personalized recommendation has been investigated for decades, the wide adoption of Latent Factor Models (LFM) has made the explainability of recommendations a critical issue to both the research community and practical application of recommender systems. For example, in many practical systems the algorithm just provides a personalized item recommendation list to the users, without persuasive personalized explanation about why such an item is recommended while another is not. Unexplainable recommendations introduce negative effects to the trustworthiness of recommender systems, and thus affect the effectiveness of recommendation engines. In this work, we investigate explainable recommendation in aspects of data explainability, model explainability, and result explainability, and the main contributions are as follows: 1. Data Explainability: We propose Localized Matrix Factorization (LMF) framework based Bordered Block Diagonal Form (BBDF) matrices, and further applied this technique for parallelized matrix factorization. 2. Model Explainability: We propose Explicit Factor Models (EFM) based on phrase-level sentiment analysis, as well as dynamic user preference modeling based on time series analysis. In this work, we extract product features and user opinions towards different features from large-scale user textual reviews based on phrase-level sentiment analysis techniques, and introduce the EFM approach for explainable model learning and recommendation. 3. Economic Explainability: We propose the Total Surplus Maximization (TSM) framework for personalized recommendation, as well as the model specification in different types of online applications. Based on basic economic concepts, we provide the definitions of utility, cost, and surplus in the application scenario of Web services, and propose the general framework of web total surplus calculation and maximization.Comment: 169 pages, in Chinese, 3 main research chapter

    Effects of Yulin Tong Bu formula on modulating gut microbiota and fecal metabolite interactions in mice with polycystic ovary syndrome

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    BackgroundPolycystic ovarian syndrome (PCOS) is a common endocrine disorder characterized by hyperandrogenism, ovarian dysfunction and polycystic ovarian morphology. Gut microbiota dysbiosis and metabolite are associated with PCOS clinical parameters. Yulin Tong Bu formula (YLTB), a traditional Chinese medicine formula, has been recently indicated to be capable of ameliorating polycystic ovary symptoms and correcting abnormal glucose metabolism. However, the therapeutic mechanism of YLTB on PCOS has not been fully elucidated.MethodsA pseudo sterile mouse model was established during this four-day acclimatization phase by giving the animals an antibiotic cocktail to remove the gut microbiota. Here, the therapeutic effects of YLTB on PCOS were investigated using dehydroepiandrosterone plus high-fat diet-induced PCOS mice model. Female prepuberal mice were randomly divided into three groups; namely, the control group, PCOS group and YLTB (38.68 g·kg-1·day-1) group. To test whether this effect is associated with the gut microbiota, we performed 16S rRNA sequencing studies to analyze the fecal microbiota of mice. The relationships among metabolites, gut microbiota, and PCOS phenotypes were further explored by using Spearman correlation analysis. Then, the effect of metabolite ferulic acid was then validated in PCOS mice.ResultsOur results showed that YLTB treatment ameliorated PCOS features (ovarian dysfunction, delayed glucose clearance, decreased insulin sensitivity, deregulation of glucolipid metabolism and hormones, etc.) and significantly attenuated PCOS gut microbiota dysbiosis. Spearman correlation analysis showed that metabolites such as ferulic acid and folic acid are negatively correlated with PCOS clinical parameters. The effect of ferulic acid was similar to that of YLTB. In addition, the bacterial species such as Bacteroides dorei and Bacteroides fragilis were found to be positively related to PCOS clinical parameters, using the association study analysis.ConclusionThese results suggest that YLTB treatment systematically regulates the interaction between the gut microbiota and the associated metabolites to ameliorate PCOS, providing a solid theoretical basis for further validation of YLTB effect on human PCOS trials
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