Simulating and Detecting the Quantum Spin Hall Effect in Kagom\'{e} Optical Lattice

We propose a model which includes a nearest-neighbor intrinsic spin-orbit coupling and a dimer Hamiltonian in the Kagom\'{e} lattice and promises to host the transition from the quantum spin Hall insulator to the normal insulator. In addition, we design an experimental scheme to simulate and detect this transition in the ultracold atom system. The lattice intrinsic spin-orbit coupling is generated via the laser-induced-gauge-field method. Furthermore, we establish the connection between the spin Chern number and the spin-atomic density which enables us to detect the topological quantum spin Hall insulator directly by the standard density-profile technique used in the atomic systems.Comment: 8 pages, 6 figure

Integration of TGF-β-induced Smad signaling in the insulin-induced transcriptional response in endothelial cells.

Insulin signaling governs many processes including glucose homeostasis and metabolism, and is therapeutically used to treat hyperglycemia in diabetes. We demonstrated that insulin-induced Akt activation enhances the sensitivity to TGF-β by directing an increase in cell surface TGF-β receptors from a pool of intracellular TGF-β receptors. Consequently, increased autocrine TGF-β signaling in response to insulin participates in insulin-induced angiogenic responses of endothelial cells. With TGF-β signaling controlling many cell responses, including differentiation and extracellular matrix deposition, and pathologically promoting fibrosis and cancer cell dissemination, we addressed to which extent autocrine TGF-β signaling participates in insulin-induced gene responses of human endothelial cells. Transcriptome analyses of the insulin response, in the absence or presence of a TGF-β receptor kinase inhibitor, revealed substantial positive and negative contributions of autocrine TGF-β signaling in insulin-responsive gene responses. Furthermore, insulin-induced responses of many genes depended on or resulted from autocrine TGF-β signaling. Our analyses also highlight extensive contributions of autocrine TGF-β signaling to basal gene expression in the absence of insulin, and identified many novel TGF-β-responsive genes. This data resource may aid in the appreciation of the roles of autocrine TGF-β signaling in normal physiological responses to insulin, and implications of therapeutic insulin usage

SIGMA: A mobility architecture for terrestrial and space networks.

Internet Protocol (IP) mobility can be handled at different layers of the protocol stack. Mobile IP has been developed to handle mobility of Internet hosts at the network layer. Mobile IP suffers from a number of drawbacks such as the requirement for infrastructure change, high handover latency, high packet loss rate, and conflict with network security solutions. As an alternative solution, a few transport layer mobility protocols have been proposed in the context of Transmission Control Protocol (TCP), for example, MSOCKS and TCP connection migration. In this dissertation, a S&barbelow; eamless I&barbelow; P-diversity-based G&barbelow; eneralized M&barbelow; obility Architecture (SIGMA) is described. SIGMA works at the transport layer and utilizes IP diversity to achieve seamless handover, and is designed to solve many of the drawbacks of Mobile IP. It can also cooperate with normal IPv4 or IPv6 infrastructure without the support of Mobile IP. The handover performance, signaling cost, and survivability issues of SIGMA are evaluated and compared with those of Mobile IP. A hierarchical location management scheme for SIGMA is developed to reduce the signaling cost of SIGMA, which is also useful to other transport layer mobility solutions. SIGMA is shown to be also applicable to managing satellite handovers in space. Finally, the interoperability between SIGMA and existing Internet security mechanisms is discussed

Electron Transfer at Iron Mineral Surface in the Presence of aqueous Sulfide and Dissolved Organic Matter under Anoxic Condition

The interaction between iron oxides and aqueous sulfide is an important biogeochemical process under anoxic water conditions, controlling in the cycling of iron and sulfur in natural system. In anoxic aquatic systems, Fe(II) and natural organic matter (NOM) are ubiquitously present. Little is known, however, how and to what extent Fe(II) and NOM affect the interactions between iron oxides and aqueous sulfide. Therefore, the role of Fe(II) and NOM on the redox reactions between iron oxides and sulfide was investigated in this thesis. The presence and speciation of Fe(II) strongly affected the pathways, rates and products of reactions between goethite and aqueous sulfide. In the absence of Fe(II) the redox reaction between structural Fe(III) of goethite and sulfide was significant and gave high yields of elemental sulfur. When suspended goethite completely adsorbed aqueous Fe(II) (Fe(II)aq), the oxidation of sulfide was severely inhibited. In the presence of significant concentrations of both Fe(II)sorb and Fe(II)aq, however, the oxidation of sulfide to elemental sulfur occurred. It is proposed that under such conditions, sulfide reacted with Fe(III) surface species that dynamically formed. The presence of Fe(II)aq is required to renew Fe(II)sorb species that partially inject electrons into bulk goethite thereby being oxidized to reactive Fe(III) at the goethite surface. Thus, the significant reaction between sulfide and goethite in the presence of Fe(II)aq was attributed to the continuous regeneration of reactive Fe(III) species at goethite surface. The presence of Aldrich humic acid (AHA) inhibited the redox reaction between sulfide with goethite due to its sorption at goethite surface, leading to a lower amount of transformation products. Within the range of applied AHA concentrations (10 mg C/L – 40 mg C/L), the coating effect of AHA played the major role in the whole reaction process, while, the redox state of AHA was insignificant. Furthermore, a small fraction of sulfide was incorporated into the AHA structure, which also contributed to the inhibition of the reaction of sulfide with goethite. The reduction of elemental sulfur by Fe(II)sorb at goethite surface was investigated at neutral pH under anoxic conditions. It was found that parallel to the reduction of S0 to sulfide by Fe(II)sorb and subsequent formation of FeS and polysulfides, S0 also was oxidized to sulfate. The occurrence of sulfur oxidation suggested the presence of reactive surface Fe(III) species. The findings of this thesis can help us to improve our understanding of the geochemical interactions in natural anoxic waters, thus eventually enabling us to apply these findings to develop techniques of pollutant transformation in anoxic groundwater systems.Die Wechselwirkung zwischen Eisenoxiden und gelöstem Sulfid ist ein wichtiger biogeochemischer Prozess in anoxischen Wässern. Die Hauptprodukte dieser Reaktion sind elementarer Schwefel und zweiwertiges Eisen, sowie gebildete metastabile Eisensulfid-Minerale, welche zu thermodynamisch stabilem Pyrit umgewandelt werden können. Daher spielen diese Reaktionen eine wichtige Rolle im Eisen- und Schwefelkreislauf in natürlichen System. In anoxischen aquatischen Systemen sind Fe(II) und natürliches organisches Material (NOM) stets vorhanden und es ist wahrscheinlich, dass diese die Reaktion zwischen Eisenoxiden und Sulfid beeinflussen. Jedoch ist wenig darüber bekannt, wie und in welchem Ausmaß dies der Fall ist. Deshalb wurde in dieser Arbeit die Rolle von Fe(II) und NOM auf die Wechselwirkung von Eisenoxiden und Sulfid untersucht. In Anbetracht der Tatsache, dass an Minerale adsorbiertes Fe(II) (Fe(II)sorb) ein hohes Reduktionspotential aufweist und elementarer Schwefel das Hauptprodukt der Oxidation von Sulfid ist, wurde ebenfalls untersucht, ob und unter welchen Bedingungen elementarer Schwefel durch Fe(II) reduziert werden kann, welches an Eisenmineralen adsorbiert ist. Die Hauptspezies von Schwefel und Eisen wurden mittels nasschemischer Analyse bestimmt. Zusätzlich wurde Mössbauer-Spektroskopie angewendet, um die mögliche Bildung sekundärer Eisenminerale zu untersuchen. Die Anwesenheit und Speziierung von Fe(II) hatte einen großen Einfluss auf den Reaktionsverlauf, und Rate, sowie die Produkte der Reaktion zwischen Goethit und gelöstem Sulfid. In der Abwesenheit von Fe(II) war die Reaktion zwischen strukturellem Fe(III) in Goethit und Sulfid ausgeprägt und hatte die Bildung hoher Konzentrationen an elementarem Schwefel zur Folge. Im Falle kompletter Adsorption von gelöstem Fe(II) (Fe(II)aq) an Goethit wurde die Oxidation von Sulfid merklich gehemmt. Jedoch fand die Oxidation von Sulfid zu elementarem Schwefel statt, wenn signifikante Mengen an Fe(II)sorb und Fe(II)aq vorhanden waren. Für dieses System wurde eine Reaktion von Sulfid mit dynamisch gebildeten Fe(III)-Oberflächenspezies hypothesiert. Hierbei ist die Anwesenheit von Fe(II)aq nötig, um erneut Fe(II)sorb-Spezies zu bilden, welche partiell Elektronen in das Goethit überführen und dadurch zu Fe(III) oxidiert wurden. Somit wurde die Reaktion von Sulfid mit Goethit in der Anwesenheit von Fe(II)aq auf die kontinuierliche Regeneration von reaktiven Fe(III)-Spezies auf der Goethit-Oberfläche zurück geführt. Hierbei konnten keine sekundären Eisenminerale mittels Mössbauer-Spektroskopie nachgewiesen werden. Die Anwesenheit von Aldrich Huminsäure (AHA) verhinderte die Redoxreaktion zwischen Sulfid und Goethit in der Anwesenheit von Fe(II) aufgrund der Adsorption der Huminsäure an die Goethit-Oberfläche. Dies führte zu geringeren Konzentrationen an Transformationsprodukten (Thiosulfat und Sulfat wurden nicht nachgewiesen). Im untersuchten AHA-Konzentrationsbereich (10 mgC/L – 40mgC/L) spielte die Bildung einer Huminsäureschicht auf der Mineraloberfläche eine ausschlaggebende Rolle für den gesamten Reaktionsprozess, wohingegen der Einfluss des Redoxzustands unerheblich war. Zudem wurde ein kleiner Teil des Sulfids in die AHA-Struktur eingebaut, was zusätzlich zu der Hemmung der Reaktion zwischen Sulfid und Goethit beitrug. Schlussendlich wurde die Reduktion von elementarem Schwefel durch Fe(II)sorb auf Goehtit unter anoxischen Bedingungen und im neutralen pH-Bereich untersucht. Neben der Reduktion von S0 zu Sulfid durch Fe(II)sorb und der darauf folgenden Bildung von FeS und Polysulfiden, wurde zudem die Oxidation von S0 zu Sulfat gezeigt. Diese Oxidation deutete auf die Anwesenheit reaktiver Fe(III)-Spezies auf der Goethit-Oberfläche hin. Goethit und Fe(II) hemmten die Bildung von Polysulfiden, da diese schnell zu Sulfid und elementarem Schwefel zerfielen. Die Ergebnisse dieser Arbeit geben neue und wichtige Einblicke in die Wechselwirkung zwischen Goethit und Sulfid in der Anwesenheit von Fe(II) und NOM. Zudem, konnte anhand der Disproportionierung von Schwefel im Goethit/Fe(II)-System nicht nur das hohe Reduktionspotential von Fe(II)sorb, sondern auch das Oxidationspotential von Fe(III)-Oberflächenspezies unter anoxischen Bedingungen gezeigt werden. Somit helfen die Ergebnisse der vorgestellten Arbeit, das Verständnis über geochemische Prozesse zu verbessern und somit möglicherweise Techniken für den Schadstoffabbau in anoxischen Grundwassersystemen zu entwickeln

Assessment of parent-subsidiary companies’ geographical distance effect on corporate social responsibility: a case of A-share listed companies

Corporate Social Responsibility (CSR) is considered as an important business agenda in the current age. Based on the data of Ashare listed companies from 2010 to 2020, this study used a fixed-effect model, heterogeneity analysis and intermediary effect test to investigate the relationship between parent-subsidiary geographical distance and CSR. Our study findings revealed that the parent-subsidiary companies’ geographic distance has a negative effect on CSR. Results of our study further indicated that the effect was more stronger for non-state-owned enterprises and the firms in the eastern region. Findings of our study also reported that the enterprise internal control had an obvious mediating effect in the association among parent-subsidiary companies’ geographic distance and CSR. The government needs to reinforce legal construction, actively guide enterprises to perform CSR through incentive measures, and implement special supervision on enterprises with a large number of subsidiaries. This study not only enriches the literature on the factors influencing corporate social responsibility but also provides a theoretical perspective and important ideas for the effective implementation of regional diversification and the improvement of CSR levels in practice

Contextual-Bandit Based Personalized Recommendation with Time-Varying User Interests

A contextual bandit problem is studied in a highly non-stationary environment, which is ubiquitous in various recommender systems due to the time-varying interests of users. Two models with disjoint and hybrid payoffs are considered to characterize the phenomenon that users' preferences towards different items vary differently over time. In the disjoint payoff model, the reward of playing an arm is determined by an arm-specific preference vector, which is piecewise-stationary with asynchronous and distinct changes across different arms. An efficient learning algorithm that is adaptive to abrupt reward changes is proposed and theoretical regret analysis is provided to show that a sublinear scaling of regret in the time length $T$ is achieved. The algorithm is further extended to a more general setting with hybrid payoffs where the reward of playing an arm is determined by both an arm-specific preference vector and a joint coefficient vector shared by all arms. Empirical experiments are conducted on real-world datasets to verify the advantages of the proposed learning algorithms against baseline ones in both settings.Comment: Accepted by AAAI 2

UXT at the crossroads of cell death, immunity and neurodegenerative diseases

The ubiquitous expressed transcript (UXT), a member of the prefoldin-like protein family, modulates regulated cell death (RCD) such as apoptosis and autophagy-mediated cell death through nuclear factor-κB (NF-κB), tumor necrosis factor-α (TNF-α), P53, P62, and methylation, and is involved in the regulation of cell metabolism, thereby affecting tumor progression. UXT also maintains immune homeostasis and reduces proteotoxicity in neuro-degenerative diseases through selective autophagy and molecular chaperones. Herein, we review and further elucidate the mechanisms by which UXT affects the regulation of cell death, maintenance of immune homeostasis, and neurodegenerative diseases and discuss the possible UXT involvement in the regulation of ferroptosis and immunogenic cell death, and targeting it to improve cancer treatment outcomes by regulating cell death and immune surveillance