SYNTHESES, STRUCTURES AND PROPERTIES OF NANOPOROUS METAL-ORGANIC FRAMEWORK MATERIALS

This dissertation describes the synthesis and characterization of a number of extended framework materials. Firstly, a series of transition metal and lanthanide metal-organic framework materials (MOFs) possessing both two and three-dimensional (2-D/ 3-D) structures as a result of linkage with different rigid carboxylate ligands have been synthesized. The crystal structures have been determined by single crystal X-ray diffraction, and their thermal/ structural stability evaluated by thermogravimetric analysis, powder neutron diffraction, in-situ and combined synchrotron powder X-ray and Raman spectroscopy. The structural stability strongly relates to the dimensionality and chemical bonding within the frameworks. In this dissertation, a geometric strategy has been proposed to elucidate these complex structures. A nanoporous structure stable up to 500oC can be obtained by dehydrating holmium MOF with 1, 3, 5-Benzene tricarboxylic acid (H3BTC) ligand. Its porosity is shown to be 879.1m2/g specific surface area by gas isotherm experiments and absorbing 1.46wt% excess of hydrogen at 77K. High resolution neutron powder diffraction has been performed on the dehydrated Ho-MOF-BTC system with P4122 chiral space group under different deuterium gas pressures and a new mechanism for gas adsorption in framework materials. A unique "helical" deuterium adsorption phenomenon results from direct interaction between the guest molecules and the non-centrosymmetric (chiral) framework architecture. Reconstruction of the nuclear scattering density using the charge flipping method has been utilized as a novel strategy for the qualitative analysis of the adsorbed molecules, in combination with maximum entropy method (MEM) density maps that provide quantitative information of the exact distribution of the diffusion pathways. In addition, the structure, magnetic and photo-luminescent properties of three lanthanide- and transition metal MOFs with shorter formate ligand are investigated by single crystal X-ray and neutron diffraction as well as solid-state fluorescence spectroscopy techniques, demonstrating unusual magnetic behaviors of Co-formate systems and strongly characteristic emission spectra from europium (Eu(III)) and terbium (Tb(III)) compounds

A Geometric View on Constrained M-Estimators

We study the estimation error of constrained M-estimators, and derive explicit upper bounds on the expected estimation error determined by the Gaussian width of the constraint set. Both of the cases where the true parameter is on the boundary of the constraint set (matched constraint), and where the true parameter is strictly in the constraint set (mismatched constraint) are considered. For both cases, we derive novel universal estimation error bounds for regression in a generalized linear model with the canonical link function. Our error bound for the mismatched constraint case is minimax optimal in terms of its dependence on the sample size, for Gaussian linear regression by the Lasso

Anticorrosive, Antimicrobial, and Bioactive Titanium Dioxide Coating for Surface‐modified Purpose on Biomedical Material

A multifunctional titanium dioxide (TiO2) coating was used to provide anticorrosive, antimicrobial, and bioactive properties for the surface modification of biomedical materials because TiO2 has a stable bonding structure, photocatalytic characteristics, and negatively charged surfaces in nature. For successful deposition, an arc ion plating technique was adopted to deposit the TiO2 coating. The antimicrobial activity values of anatase‐TiO2‐coated stainless steel specimens against Staphylococcus aureus and Escherichia coli were 3.0 and 2.5, respectively, which are far beyond the value designated in JIS Z2801:2000 industrial standard. TiO2 coatings on stainless steel also generate an increased (i.e., less negative) corrosion potential and decreased corrosion current in a sodium chloride solution, showing a reduced tendency and rate of substrate dissolution as well as a reduced coating of species into the electrolyte. In addition, TiO2 coatings, especially with rutile phase, satisfied the requirements for activating the biological property of a polymeric polyetheretherketone surface. Therefore, TiO2 is a promising surface modification for the biomedical materials used in surgical instruments and implants

Factors Affecting Caregivers’ Perceptions of Residents’ Oral Health in Long-Term Care Facilities in Taiwan

[[abstract]]The purpose of this study was to investigate the differences between resident oral care policies provided by 2 types of long-term care (LTC) institutions. The study also investigated factors affecting LTC institutional caregivers' perceptions of the residents' oral health. Overall, 103 completed questionnaires were returned. Of these, 44 were from senior citizen welfare institutions, and 59 were from nursing homes. The variables affecting these perceptions included institution type and whether the residents attended hospital dental clinics or consulted a hospital doctor regarding oral health problems. The research results showed that institution type and whether an oral care-related professional was available in an institution were correlated with an increase in institutional caregivers' perceptions of oral care

Psychosocial Determinants of Insomnia in Adolescents: Roles of Mental Health, Behavioral Health, and Social Environment

The theoretical explanation of human problems is derived from the complex interplay of psychological, social, economic, political, and physical factors. Aims: This study examined the roles of behavioral health (i.e., alcohol abuse and suicidality) and social environment (i.e., family support, school connectedness, and favorable neighborhood) and mental health [i.e., depression, anxiety, and attention deficit hyperactivity disorder (ADHD)] in predicting insomnia in adolescents in an ecological perspective. Methods: Approximately 6445 high school students in Taiwan were administered an anonymous self-report survey. Hierarchical multiple regression was performed to examine how multidimensional social environment, behavioral health, and mental health factors were associated with insomnia in adolescents. Results: The prevalence rate of insomnia in the sample was 30%. The results indicated that alcohol abuse (β = 0.04), suicidality (β = 0.06), depression (β = 0.29), anxiety (β = 0.14), and ADHD (β = 0.11) were positively associated with insomnia (p \u3c 0.001), whereas family support (β = −0.06), school connectedness (β = −0.05), and favorable neighborhood (β = −0.10) were negatively associated with insomnia (p \u3c 0.001). Sex did not predict insomnia, but age was positively associated with insomnia (β = 0.09, p \u3c 0.001). Among all predictors of insomnia in the study, mental health factors, especially depression, play a major role on insomnia among adolescents, and is as much important as social environment factors. Conclusion: This study demonstrated how both psychosocial variables (social environment and behavioral health) and psychological symptoms were associated with insomnia in adolescents when the demographic variables (sex and age) were controlled and provided valuable information and evidence for clinicians, social workers, and health professionals who provide support to adolescents with insomnia. Applying an ecological approach in practice can aid in understanding at individual, family, school, and community levels and in identifying the strengths and weaknesses of their interactions with each other. Implications: This perspective enables practitioners in effectively treating problems and addressing the needs of the various levels, including the individual, family, school, and the broader community. Thus, prevention and intervention of insomnia in adolescents should focus on multidimensional risk and protective factors, including mental health, behavioral health, and social environment, in the context of an ecological system

Accelerated Policy Gradient: On the Nesterov Momentum for Reinforcement Learning

Policy gradient methods have recently been shown to enjoy global convergence at a $\Theta(1/t)$ rate in the non-regularized tabular softmax setting. Accordingly, one important research question is whether this convergence rate can be further improved, with only first-order updates. In this paper, we answer the above question from the perspective of momentum by adapting the celebrated Nesterov's accelerated gradient (NAG) method to reinforcement learning (RL), termed \textit{Accelerated Policy Gradient} (APG). To demonstrate the potential of APG in achieving faster global convergence, we formally show that with the true gradient, APG with softmax policy parametrization converges to an optimal policy at a $\tilde{O}(1/t^2)$ rate. To the best of our knowledge, this is the first characterization of the global convergence rate of NAG in the context of RL. Notably, our analysis relies on one interesting finding: Regardless of the initialization, APG could end up reaching a locally nearly-concave regime, where APG could benefit significantly from the momentum, within finite iterations. By means of numerical validation, we confirm that APG exhibits $\tilde{O}(1/t^2)$ rate as well as show that APG could significantly improve the convergence behavior over the standard policy gradient.Comment: 51 pages, 8 figure

Coordinate Ascent for Off-Policy RL with Global Convergence Guarantees

We revisit the domain of off-policy policy optimization in RL from the perspective of coordinate ascent. One commonly-used approach is to leverage the off-policy policy gradient to optimize a surrogate objective -- the total discounted in expectation return of the target policy with respect to the state distribution of the behavior policy. However, this approach has been shown to suffer from the distribution mismatch issue, and therefore significant efforts are needed for correcting this mismatch either via state distribution correction or a counterfactual method. In this paper, we rethink off-policy learning via Coordinate Ascent Policy Optimization (CAPO), an off-policy actor-critic algorithm that decouples policy improvement from the state distribution of the behavior policy without using the policy gradient. This design obviates the need for distribution correction or importance sampling in the policy improvement step of off-policy policy gradient. We establish the global convergence of CAPO with general coordinate selection and then further quantify the convergence rates of several instances of CAPO with popular coordinate selection rules, including the cyclic and the randomized variants of CAPO. We then extend CAPO to neural policies for a more practical implementation. Through experiments, we demonstrate that CAPO provides a competitive approach to RL in practice.Comment: 47 pages, 4 figure

Development and Validation of the Parents\u27 Perceived Self-Efficacy to Manage Children\u27s Internet Use Scale for Parents of Adolescents with Attention-Deficit/Hyperactivity Disorder

Background and aims: This study developed and validated the Parents’ Perceived Self-Efficacy to Manage Children’s Internet Use Scale (PSMIS) in the parents of children with attention-deficit/hyperactivity disorder (ADHD). Methods: In total, 231 parents of children with ADHD were invited to complete the PSMIS, followed by the Chen Internet Addiction Scale and the short version of Swanson, Nolan, and Pelham, Version IV Scale – Chinese version for analyzing Internet addiction severity and ADHD symptoms, respectively. Results: The results of exploratory and confirmatory factor analyses confirmed the four-factor structure of the 18-item PSMIS. The significant difference in the levels of parents’ perceived self-efficacy between the parents of children with and without Internet addiction supported the criterion-related validity of the PSMIS. The internal consistency and 1-month test–retest reliability were acceptable. Conclusion: The results indicate that the PSMIS has acceptable validity and reliability and can be used for measuring parents’ perceived self-efficacy to manage children’s Internet use among parents of children with ADHD

Estimation Error of the Constrained Lasso

This paper presents a non-asymptotic upper bound for the estimation error of the constrained lasso, under the high-dimensional ($n \ll p$) setting. In contrast to existing results, the error bound in this paper is sharp, is valid when the parameter to be estimated is not exactly sparse (e.g., when it is weakly sparse), and shows explicitly the effect of over-estimating the $\ell_1$-norm of the parameter to be estimated on the estimation performance. The results of this paper show that the constrained lasso is minimax optimal for estimating a parameter with bounded $\ell_1$-norm, and also for estimating a weakly sparse parameter if its $\ell_1$-norm is accessible

Toxicity risk of non-target organs at risk receiving low-dose radiation: case report

The spine is the most common site for bone metastases. Radiation therapy is a common treatment for palliation of pain and for prevention or treatment of spinal cord compression. Helical tomotherapy (HT), a new image-guided intensity modulated radiotherapy (IMRT), delivers highly conformal dose distributions and provides an impressive ability to spare adjacent organs at risk, thus increasing the local control of spinal column metastases and decreasing the potential risk of critical organs under treatment. However, there are a lot of non-target organs at risk (OARs) occupied by low dose with underestimate in this modern rotational IMRT treatment. Herein, we report a case of a pathologic compression fracture of the T9 vertebra in a 55-year-old patient with cholangiocarcinoma. The patient underwent HT at a dose of 30 Gy/10 fractions delivered to T8-T10 for symptom relief. Two weeks after the radiotherapy had been completed, the first course of chemotherapy comprising gemcitabine, fluorouracil, and leucovorin was administered. After two weeks of chemotherapy, however, the patient developed progressive dyspnea. A computed tomography scan of the chest revealed an interstitial pattern with traction bronchiectasis, diffuse ground-glass opacities, and cystic change with fibrosis. Acute radiation pneumonitis was diagnosed. Oncologists should be alert to the potential risk of radiation toxicities caused by low dose off-targets and abscopal effects even with highly conformal radiotherapy