Comparing sets of data sets on the Grassmann and flag manifolds with applications to data analysis in high and low dimensions

Includes bibliographical references.2020 Summer.This dissertation develops numerical algorithms for comparing sets of data sets utilizing shape and orientation of data clouds. Two key components for "comparing" are the distance measure between data sets and correspondingly the geodesic path in between. Both components will play a core role which connects two parts of this dissertation, namely data analysis on the Grassmann manifold and flag manifold. For the first part, we build on the well known geometric framework for analyzing and optimizing over data on the Grassmann manifold. To be specific, we extend the classical self-organizing mappings to the Grassamann manifold to visualize sets of high dimensional data sets in 2D space. We also propose an optimization problem on the Grassmannian to recover missing data. In the second part, we extend the geometric framework to the flag manifold to encode the variability of nested subspaces. There we propose a numerical algorithm for computing a geodesic path and distance between nested subspaces. We also prove theorems to show how to reduce the dimension of the algorithm for practical computations. The approach is shown to have advantages for analyzing data when the number of data points is larger than the number of features

The unique N-terminal sequence of the BKCa channel α-subunit determines its modulation by β-subunits

Large conductance voltage- and Ca2+-activated K+ (BKCa) channels are essential regulators of membrane excitability in a wide variety of cells and tissues. An important mechanism of modulation of BKCa channel activity is its association with auxiliary subunits. In smooth muscle cells, the most predominant regulatory subunit of BKCa channels is the β1-subunit. We have previously described that BKCa channels with distinctive N-terminal ends (starting with the amino acid sequence MDAL, MSSN or MANG) are differentially modulated by the β1-subunit, but not by the β2. Here we extended our studies to understand how the distinct N-terminal regions differentially modulate channel activity by β-subunits. We recorded inside-out single-channel currents from HEK293T cells co-expressing the BKCa containing three N-terminal sequences with two β1-β2 chimeric constructs containing the extracellular loop of β1 or β2, and the transmembrane and cytoplasmic domains of β2 or β1, respectively. Both β chimeric constructs induced leftward shifts of voltage-activation curves of channels starting with MANG and MDAL, in the presence of 10 or 100 μM intracellular Ca2+. However, MSSN showed no shift of the voltage-activation, at the same Ca2+ concentrations. The presence of the extracellular loop of β1 in the chimera resembled results seen with the full β1 subunit, suggesting that the extracellular region of β1 might be responsible for the lack of modulation observed in MSSN. We further studied a poly-serine stretch present in the N-terminal region of MSSN and observed that the voltage-activation curves of BKCa channels either containing or lacking this poly-serine stretch were leftward shifted by β1-subunit in a similar way. Overall, our results provide further insights into the mechanism of modulation of the different N-terminal regions of the BKCa channel by β-subunits and highlight the extension of this region of the channel as a form of modulation of channel activity

A 14-mW PLL-less receiver in 0.18-μm CMOS for Chinese electronic toll collection standard

This is the accepted manuscript version of the following article: Xiaofeng He, et al., “A 14-mW PLL-less receiver in 0.18-μm CMOS for Chinese electronic toll collection standard”, IEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 61(10): 763-767, August 2014. The final published version is available at: http://ieeexplore.ieee.org/document/6871304/ © 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The design of a 14-mW receiver without phase-locked loop for the Chinese electronic toll collection (ETC) system in a standard 0.18-μm CMOS process is presented in this brief. Since the previously published work was mainly based on vehicle-powered systems, low power consumption was not the primary goal of such a system. In contrast, the presented system is designed for a battery-powered system. Utilizing the presented receiver architecture, the entire receiver only consumes 7.8 mA, at the supply voltage of 1.8 V, which indicates a power saving of at least 38% compared with other state-of-the-art designs for the same application. To verify the performance, the bit error rate is measured to be better than 10-6, which well satisfies the Chinese ETC standard. Moreover, the sensitivity of the designed receiver can be readjusted to -50 dBm, which is required by the standard.Peer reviewe

El rol de la motivación en los efectos de las relaciones profesor-estudiante en el rendimiento de la lengua extranjera

The present study investigated whether students’ motivational beliefs act as a mediator in the association between teacher-student relationships (TSRs) and foreign language performance with a multiple mediation model. Furthermore, this research examined whether mediating roles of intrinsic and extrinsic motivation differ. A total of 1171 eighth graders (583 male, 588 female) were chosen with purposive sampling in China. Studentreported measures of TSRs, intrinsic and extrinsic motivation, and English as a Foreign Language (EFL) test based on national curriculum were administrated in October 2017. Results showed that the positive link between TSRs and foreign language performance is partially mediated by intrinsic and extrinsic motivation, and the mediation effect of intrinsic motivation is significantly greater than that of extrinsic motivation, controlling for gender and socio-economic status. The results indicated that supportive TSRs can help learners to improve their foreign language proficiency by promoting their motivation, especially intrinsic motivation. The present results may have substantive theoretical and practical implications for teacher education and foreign language learning.El presente estudio investigó si las creencias motivacionales de los estudiantes actúan como mediadores en la asociación entre las relaciones profesor-alumno (TSR) y el rendimiento de un idioma extranjero con un modelo de mediación múltiple. Además, esta investigación examinó si los roles mediadores de la motivación intrínseca y extrínseca difieren. Se eligieron 1171 alumnos de octavo grado (583 hombres, 588 mujeres) con muestreo intencional en China. En octubre de 2017, se aplicaron a los estudiantes las pruebas de TSR, la motivación intrínseca y extrínseca y la prueba de inglés como idioma extranjero (EFL) basadas en el plan de estudios nacional. Los resultados mostraron que el vínculo positivo entre TSR y el desempeño de un idioma extranjero está parcialmente mediado por la motivación intrínseca y extrínseca, y el efecto de mediación de la motivación intrínseca es significativamente mayor que el de la motivación extrínseca, controlando el género y el estatus socioeconómico. Los resultados indicaron que los TSR de apoyo pueden ayudar a los alumnos a mejorar su dominio del idioma extranjero ya que promueven su motivación, especialmente la motivación intrínseca. Los resultados actuales pueden tener importantes implicaciones teóricas y prácticas para la formación del profesorado y el aprendizaje de lenguas extranjeras.&nbsp

El rol de la motivación en los efectos de las relaciones profesor-estudiante en el rendimiento de la lengua extranjera

The present study investigated whether students’ motivational beliefs act as a mediator in the association between teacher-student relationships (TSRs) and foreign language performance with a multiple mediation model. Furthermore, this research examined whether mediating roles of intrinsic and extrinsic motivation differ. A total of 1171 eighth graders (583 male, 588 female) were chosen with purposive sampling in China. Studentreported measures of TSRs, intrinsic and extrinsic motivation, and English as a Foreign Language (EFL) test based on national curriculum were administrated in October 2017. Results showed that the positive link between TSRs and foreign language performance is partially mediated by intrinsic and extrinsic motivation, and the mediation effect of intrinsic motivation is significantly greater than that of extrinsic motivation, controlling for gender and socio-economic status. The results indicated that supportive TSRs can help learners to improve their foreign language proficiency by promoting their motivation, especially intrinsic motivation. The present results may have substantive theoretical and practical implications for teacher education and foreign language learning.El presente estudio investigó si las creencias motivacionales de los estudiantes actúan como mediadores en la asociación entre las relaciones profesor-alumno (TSR) y el rendimiento de un idioma extranjero con un modelo de mediación múltiple. Además, esta investigación examinó si los roles mediadores de la motivación intrínseca y extrínseca difieren. Se eligieron 1171 alumnos de octavo grado (583 hombres, 588 mujeres) con muestreo intencional en China. En octubre de 2017, se aplicaron a los estudiantes las pruebas de TSR, la motivación intrínseca y extrínseca y la prueba de inglés como idioma extranjero (EFL) basadas en el plan de estudios nacional. Los resultados mostraron que el vínculo positivo entre TSR y el desempeño de un idioma extranjero está parcialmente mediado por la motivación intrínseca y extrínseca, y el efecto de mediación de la motivación intrínseca es significativamente mayor que el de la motivación extrínseca, controlando el género y el estatus socioeco-nómico. Los resultados indicaron que los TSR de apoyo pueden ayudar a los alumnos a mejorar su dominio del idioma extranjero ya que promueven su motivación, especialmente la motivación intrínseca. Los resultados actuales pueden tener importantes implicaciones teóricas y prácticas para la formación del profesorado y el aprendizaje de lenguas extranjera

A phage-displayed peptide recognizing porcine aminopeptidase N is a potent small molecule inhibitor of PEDV entry

Three phage-displayed peptides designated H, S and F that recognize porcine aminopeptidase N (pAPN), the cellular receptor of porcine transmissible gastroenteritis virus (TGEV) were able to inhibit cell infection by TGEV. These same peptides had no inhibitory effects on infection of Vero cells by porcine epidemic diarrhea virus (PEDV). However, when PEDV, TGEV and porcine pseudorabies virus were incubated with peptide H (HVTTTFAPPPPR), only infection of Vero cells by PEDV was inhibited. Immunofluorescence assays indicated that inhibition of PEDV infection by peptide H was independent of pAPN. Western blots demonstrated that peptide H interacted with PEDV spike protein and that pre-treatment of PEDV with peptide H led to a higher inhibition than synchronous incubation with cells. These results indicate direct interaction with the virus is necessary to inhibit infectivity. Temperature shift assays demonstrated that peptide H inhibited pre-attachment of the virus to the cells

High-density Vero cell perfusion culture in BioBLU 5p Single-Use Vessels

Vero cells are anchorage-dependent cells that are widely used as a platform for viral vaccine production. In stirred-tank bioreactors, they are ordinarily grown on microcarriers. Fibra-Cel® disks are a promising alternative attachment matrix with a high surface-to-volume ratio. They provide a three-dimensional environment that protects cells from damaging shear forces, helping to achieve high cell densities. In this study, we cultivated Vero cells in Eppendorf BioBLU 5p Single-Use Vessels pre-packed with Fibra-Cel. The process was controlled with a BioFlo® 320 bioprocess control station. We cultivated the cells in perfusion mode, which ensures a consistent supply of nutrients and the removal of toxic byproducts. We achieved the very high Vero cell density of approximately 43 million cells per mL, demonstrating great potential for Vero-cell-based vaccine production using Fibra-Cel packed-bed vessels