Prediction of time series by statistical learning: general losses and fast rates

We establish rates of convergences in time series forecasting using the statistical learning approach based on oracle inequalities. A series of papers extends the oracle inequalities obtained for iid observations to time series under weak dependence conditions. Given a family of predictors and $n$ observations, oracle inequalities state that a predictor forecasts the series as well as the best predictor in the family up to a remainder term $\Delta_n$. Using the PAC-Bayesian approach, we establish under weak dependence conditions oracle inequalities with optimal rates of convergence. We extend previous results for the absolute loss function to any Lipschitz loss function with rates $\Delta_n\sim\sqrt{c(\Theta)/ n}$ where $c(\Theta)$ measures the complexity of the model. We apply the method for quantile loss functions to forecast the french GDP. Under additional conditions on the loss functions (satisfied by the quadratic loss function) and on the time series, we refine the rates of convergence to $\Delta_n \sim c(\Theta)/n$. We achieve for the first time these fast rates for uniformly mixing processes. These rates are known to be optimal in the iid case and for individual sequences. In particular, we generalize the results of Dalalyan and Tsybakov on sparse regression estimation to the case of autoregression

Topological field-effect transistor with quantized ON/OFF conductance of helical/chiral dislocation states

Topology is a key ingredient driving the emergence of quantum devices. Topological field-effect transistor (TFET) has been proposed to outperform the conventional FET by replacing the ON state with topology-protected quantized conductance, while the OFF state remains the same normal insulating characteristics and hence bears similar drawbacks. Here, we demonstrate a proof-of-concept TFET having both ON and OFF quantized conductance, by switching between helical and chiral topological screw dislocation (SD) states in three-dimensional topological insulators. A pair of SDs are configured with one acting as channel and the other as gate controlled by local magnetic field. A reversible field-switching is achieved with the ON and OFF conductance of $2e^2/h$ and $e^2/h$, respectively, as shown by tight-binding quantum transport calculations. Furthermore, BaBiO$_3$ is shown as a candidate material having the desired topological SD states, based on first-principles calculations. Our findings open a new route to high-fidelity topological quantum devices

Higher-order Topological Point State

Higher-order topological insulators (HOTIs) have attracted increasing interest as a unique class of topological quantum materials. One distinct property of HOTIs is the crystalline symmetry-imposed topological state at the lower-dimensional outer boundary, e.g. the zero-dimensional (0D) corner state of a 2D HOTI, used exclusively as a universal signature to identify higher-order topology but yet with uncertainty. Strikingly, we discover the existence of inner topological point states (TPS) in a 2D HOTI, as the embedded "end" states of 1D first-order TI, as exemplified by those located at the vacancies in a Kekule lattice. Significantly, we demonstrate that such inner TPS can be unambiguously distinguished from the trivial point-defect states, by their unique topology-endowed inter-TPS interaction and correlated magnetic response in spectroscopy measurements, overcoming an outstanding experimental challenge. Furthermore, based on first-principles calculations, we propose {\gamma}-graphyne as a promising material to observe the higher-order TPS. Our findings shed new light on our fundamental understanding of HOTIs, and also open an avenue to experimentally distinguishing and tuning TPS in the interior of a 2D sample for potential applications

Light and intermittent smoking among young adults : trends and transitions

Although smoking prevalence has declined, very light smoking (5 or fewer cigarettes per day) is still very common among young adults. The limited available literature indicates that emerging alternative tobacco use may play a role in the prevalence and progression of very light smoking among young adults. The current dissertation involved two studies examining trends and transitions of very light smoking and investigating the demographic and behavioral corelates of these trends and transitions. Study 1 fills the research gap by examining the trends of light smoking among young adults (18-25 year) during the past decade. The roles of demographic factors (such as sex, race/ethnicity, age group, and educational status) and other tobacco use status (such as daily smoking status and use of alternative tobacco) in trends of light smoking among young adults were also explored. The research sample was selected from the public national database, the NSDUH (National Survey on Drug Use and Health), 2002-2015. Findings suggested that the long-term smoking trends among young adults were nonlinear and the trends varied in different subgroups of young adults. The general decline in very light smoking among young adults masks the different trends in certain time periods, tobacco use groups and demographic subpopulations. Tailored policies and prevention programs are needed to benefit subpopulations of young adults. Study 2 examines transitions of cigarette smoking among college students across two and half years using six semi-annual waves of online data from the Project M-PACT study (Marketing and Promotions Across Colleges in Texas), supported by the National Cancer Institute and the FDA Center for Tobacco Products (CTP). Using Markov models, the author examined changes in states of current smoking among college students within time intervals of various duration, and also investigated the roles of sex and alternative tobacco use in smoking status and transition. The results showed that the transitions of smoking status among college students were associated with starting smoking status, the duration of the interval, sex and the use of alternative tobacco products. These findings highlight the need to identify priorities for tobacco control programs and policies among college studentsKinesiology and Health Educatio

Hypothalamic regulation of pancreatic secretion is mediated by central cholinergic pathways in the rat

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65667/1/j.1469-7793.2003.00571.x.pd

Baicalin Downregulates RLRs Signaling Pathway to Control Influenza A Virus Infection and Improve the Prognosis

The objective of this study is to investigate the effects of baicalin on controlling the pulmonary infection and improving the prognosis in influenza A virus (IAV) infection. PCR and western blot were used to measure the changes of some key factors in RLRs signaling pathway. MSD electrochemiluminescence was used to measure the expression of pulmonary inflammatory cytokines including IFN-γ, TNF-α, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p70, and KC/GRO. Flow cytometry was used to detect the proportion of Th1, Th2, Th17, and Treg. The results showed that IAV infection led to low body weight and high viral load and high expression of RIG-I, IRF3, IRF7, and NF-κB mRNA, as well as RIG-I and NF-κB p65 protein. However, baicalin reduced the rate of body weight loss, inhibited virus replication, and downregulated the key factors of the RLRs signaling pathway. Besides, baicalin reduced the high expression inflammatory cytokines in lung and decreased the ratios of Th1/Th2 and Th17/Treg to arouse a brief but not overviolent inflammatory response. Therefore, baicalin activated a balanced host inflammatory response to limit immunopathologic injury, which was helpful to the improvement of clinical and survival outcomes

Molecular-size dependence of glycogen enzymatic degradation and its importance for diabetes

Glycogen, a hyperbranched glucose polymer, is the blood-sugar reservoir in animals. Liver glycogen comprises small β particles, which can join together as large composite α particles. It had been shown that the binding between β in α particles in the liver of diabetic mice is more fragile than in healthy mice. This could be linked to the loss of blood-sugar control characteristic of diabetes if the rate per monomer unit of the enzymatic degradation to glucose of α particles were significantly slower than that of β particles. This is tested here by examining the in vitro time evolution of the molecular size distribution of glycogen from the livers of healthy and diabetic mice and rats, containing distinct components of both α and β particles; this treatment is analogous to the “competitive growth” method used to explore mechanisms in emulsion polymerization. Simulations for the time evolution of the molecular size distribution were also performed. It is found that the degradation rate per monomer unit is indeed faster for the smaller particles, supporting the hypothesis of a causal link between chemical fragility of glycogen from diabetic liver with poor control of blood-sugar release. Comparison between simulations and experiment indicate that α and β particles have significant structural differences