Quantifizierung struktureller Veränderungen im kortikalen Knochen durch Abschätzung von Dicke, Schallgeschwindigkeit und Porengrößenverteilung

Quantitative bone ultrasound (QUS) method has been introduced as a promising alternative for diagnosing osteoporosis and assessing fracture risk. The latest QUS technologies aim to quantitatively assess structural cortical bone characteristics, e.g, cortical porosity, cortical thickness (Ct.Th) and cortical speed of sound at cortical measurement regions. Large cortical pores and reduced Ct.Th in the tibia have been proposed as an indication of reduced hip strength and structural deterioration. In this work two novel ultrasound methods were studied using a conventional ultrasound transducer to measure cortical bone properties at the tibia. The first method is a refraction and phase aberration corrected multifocus (MF) imaging approach that measures Ct.Th and the compressional sound velocity traveling in the radial bone direction (Ct.ν11). The second method is a novel cortical backscatter (CortBS) method that assesses microstructural properties in cortical bone. Both methods were validated in silico on bone models, ex vivo on bone samples and in vivo on 55 postmenopausal women at the anteromedial tibia midshaft. The aim of this work was to study the precision, accuracy, and fragility fracture discrimination performance of CortBS and MF parameters in comparison to clinical High-resolution peripheral quantitative computed tomography (HR-pQCT) and Dual-energy X-ray absorptiometry (DXA) measurements. The results of the MF approach show precise and accurate estimation of Ct.Th and Ct.ν11. The comparison of the measured Ct.Th with reference thicknesses from HR-pQCT measurement have also shown accurate determination of Ct.Th (R2=0.94, RMSE=0.17 mm). Future simulation studies with real bone structures from HR-pQCT measurements should target the validation of accurate Ct.ν11 estimation. For the first time, CortBS assessed the distribution of cortical pore size and viscoelastic properties of cortical bone in vivo. The short- term in vivo precision was observed between 1.7% and 13.9%. Fragility fracture discrimination performance was retrieved using multivariate partial least squares regression. The combination of CortBS+MF showed superior fracture discrimination performance compared with DXA and similar fracture discrimination performance compared with HR-pQCT. Further clinical studies with larger cohort size should target the potential to demonstrate the ability of CortBS and MF parameters for individual fracture risk assessment. In conclusion, alteration in cortical microstructure and viscoelasticity caused by the aging process and the progression of osteoporosis can be measured by CortBS and MF. These methods have high potential to identify patients at high risk for fragility fractures.Die quantitative Knochenultraschallmethode (QUS) wurde als vielversprechende Alternative für die Diagnose von Osteoporose und die Bewertung des Frakturrisikos eingeführt. Die neuesten QUS-Technologien zielen darauf ab, strukturelle kortikale Knochenmerkmale, z. B. kortikale Porosität, kortikale Dicke (Ct.Th) und kortikale Schallgeschwindigkeit in kortikalen Messregionen quantitativ zu bewerten. Große kortikale Poren und eine verringerte Ct.Th in der Tibia wurden als Anzeichen für eine verringerte Festigkeit der Hüfte und eine strukturelle Verschlechterung vorgeschlagen. In dieser Arbeit wurden zwei neuartige Ultraschallmethoden unter Verwendung eines herkömmlichen Ultraschallwandlers zur Messung der Eigenschaften am kortikalen Knochen des Schienbeins untersucht. Bei der ersten Methode handelt es sich um einen brechungs- und phasenaberrationskorrigierten multifokalen (MF) Bildgebungsansatz, der Ct.Th und die Kompressionsschallgeschwindigkeit in radialer Knochenrichtung (Ct.ν11) misst. Die zweite Methode ist eine neuartige kortikale Rückstreumethode (CortBS), die die mikrostrukturellen Eigenschaften des kortikalen Knochens misst. Beide Methoden wurden in silico an Knochenmodellen, ex vivo an Knochenproben und in vivo an 55 postmenopausalen Frauen am anteromedialen Tibia-Mittelschaft validiert. Ziel dieser Arbeit war es, die Präzision, Genauigkeit und Fragilitätsfraktur-Diskriminierungsleistung von CortBS- und MF-Parametern im Vergleich zur klinischen hochauflösenden peripheren quantitativen Computertomographie (HR-pQCT) und Dualen-Energie-Röntgenabsorptiometrie (DXA) zu untersuchen. Die Ergebnisse des MF-Ansatzes zeigen eine präzise und genaue Schätzung von Ct.Th und Ct.ν11. Der Vergleich der gemessenen Ct.Th mit Referenzdicken aus HR-pQCT-Messungen hat ebenfalls eine genaue Bestimmung der Ct.Th gezeigt (R2=0,94, RMSE=0,17 mm). Zukünftige Simulationsstudien mit realen Knochenstrukturen aus HR-pQCT-Messungen sollten die genauen Schätzung der Ct.ν11 validieren. Zum ersten Mal hat CortBS die kortikale Porengrößenverteilung und die viskoelastischen Eigenschaften des kortikalen Knochens in vivo untersucht. Die kurzfristige In-vivo-Präzision lag zwischen 1,7% und 13,9%. Die Fragilitätsfraktur-Diskriminierungsleistung wurde mittels multivarianter Regression der partiellen kleinsten Quadrate bewertet. Die Kombination von CortBS+MF zeigte im Vergleich zur DXA eine überlegene Leistung bei der Frakturerkennung und eine ähnliche Leistung wie die bei HR-pQCT. Weitere klinische Studien mit größerer Kohortengröße sollten die Fähigkeit von CortBS- und MF-Parametern zur individuellen Frakturrisikobewertung nachweisen. Zusammenfassend lässt sich sagen, dass Veränderungen der kortikalen Mikrostruktur und Viskoelastizität, die durch den Alterungsprozess und das Fortschreiten der Osteoporose verursacht werden, mit CortBS und MF gemessen werden können. Diese Methoden haben ein hohes Potenzial zur Identifizierung von Patienten mit hohem Risiko für Fragilitätsfrakturen

China after Mao: from reforms to Tiananmen

Ústav politologieInstitute of Political ScienceFilozofická fakultaFaculty of Art

Social delay tolerant approach for safety services in vehicular networks

Vehicular networks have attracted attention for recent years due to their various and emerging applications supporting secure and convenient driving. Regarding specific features of vehicular networks, we propose a new Social-aware Vehicular DTN protocol (SocVe) respectively for a type of safety applications such as emergency support services. We evaluate our protocol in short contact and intermittent connection scenarios extracting from mobility data set in Hanoi city. We conduct comparative performance evaluation of SocVe in multiple scenarios with different destination centralities against a geographical protocol

Asian Values and Human Rights: A Vietnamese Perspective

This paper examines the impact of the ideology of ‘Asian Values' on the legal norms and practices that frame the recognition and protection of human rights in Vietnam. Specifically, the paper focusses on the extent to which Asian Values has been deployed to discourage the adoption of international human rights norms and practices in the context of Vietnam’s rapid economic development since the mid- 1980s. The paper first sketches the adoption of Asian Values in Vietnam’s politics and society. Cultural and political factors that have shaped the conception of human rights are reviewed. Human rights language and norms, as manifest in political ideologies, policies and laws are then analysed, with particular reference to the different versions of Vietnam’s Constitution. It is shown that both the Communist Party of Vietnam (CPV) and the State of Vietnam have clearly articulated Asian Values in formulating their conceptions of human rights. This outcome is argued to result from the fact that Vietnamese political leaders, alike with Lee Kwan Yew in Singapore, the progenitor of Asian Rights, have been strongly influenced by Confucian ideals of governance. Confucianism is not, however, the only basis for political ideas in Vietnam. Although Vietnam is a market economy it remains a one- party state  controlled  by  the  CPV.  The  Marxist-Leninist  principles  on  which the current State of Vietnam was based at its inception in 1975 remain intact. This ideology was however layered onto generations of collectivist principles embodied in the dominant agrarian society. The influence of Asian Values, on the recognition of and support for human rights in Vietnam has, however, been largely negative rather than positive, especially in relation to recognising civil and political rights as codified in universal human rights instruments. Thus, the protection and promotion of human rights in Vietnam, going forward, essentially mandates eliminating the influence of Asian Values in the ideology of political leaders and in the wider society. Key words: Human rights, Asian Values, democracy, constitution, Communist Party, Vietna

Estimation of Thickness and Speed of Sound for Transverse Cortical Bone Imaging Using Phase Aberration Correction Methods: An In Silico and Ex Vivo Validation Study

Delay-and-sum (DAS) beamforming of backscattered echoes is used for conventional ultrasound imaging. Although DAS beamforming is well suited for imaging in soft tissues, refraction, scattering, and absorption, porous mineralized tissues cause phase aberrations of reflected echoes and subsequent image degradation. The recently developed refraction corrected multi-focus technique uses subsequent focusing of waves at variable depths, the tracking of travel times of waves reflected from outer and inner cortical bone interfaces, the estimation of the shift needed to focus from one interface to another to determine cortical thickness (Ct.Th), and the speed of sound propagating in a radial bone direction (Ct.nu(11)). The method was validated previously in silico and ex vivo on plate shaped samples. The aim of this study was to correct phase aberration caused by bone geometry (i.e., curvature and tilt with respect to the transducer array) and intracortical pores for the multi-focus approach. The phase aberration correction methods are based on time delay estimation via bone geometry differences to flat bone plates and via the autocorrelation and cross correlation of the reflected ultrasound waves from the endosteal bone interface. We evaluate the multi-focus approach by incorporating the phase aberration correction methods by numerical simulation and one experiment on a human tibia bone, and analyze the precision and accuracy of measuring Ct.Th and Ct.nu(11). Site-matched reference values of the cortical thickness of the human tibia bone were obtained from high-resolution peripheral computed tomography. The phase aberration correction methods resulted in a more precise (coefficient of variation of 5.7%) and accurate (root mean square error of 6.3%) estimation of Ct.Th, and a more precise (9.8%) and accurate (3.4%) Ct.nu(11) estimation, than without any phase aberration correction. The developed multi-focus method including phase aberration corrections provides local estimations of both cortical thickness and sound velocity and is proposed as a biomarker of cortical bone quality with high clinical potential for the prevention of osteoporotic fractures

Two Higgs doublet model fitting and ttˉbbˉt\bar{t}b\bar{b} signal at the ILC

One of the most straightforward extensions of the standard model (SM) is having an additional Higgs doublet to the SM, namely the two Higgs doublet models(THDM). In the type-I model, an additional Higgs doublet is introduced that does not couple to any fermion via the Yukawa interaction. Considering various theoretical and phenomenological constraints, we have found the best-fitted parameter set in the type-I model using the minimum $\chi^2$ method by scanning the model's parameter space. We show that this optimal parameter set can be probed by precisely analyzing the decay processes $D^+ \rightarrow \mu^+ \nu_\mu$, $B^0 \rightarrow K^* \mu^+ \mu^-$. Moreover, the decay channels $h \rightarrow s\bar{s}$, $W^+W^-$ and $gg$ can be used to distinguish the model from the SM. For a direct search of the model at future colliders, we have proposed an investigation of the $e^+e^- \rightarrow t\bar{t} b\bar{b}$ process at the ILC to detect the new physics of the model. Considering the initial state radiation correction and applying appropriate background cuts, the calculation result of the scattering cross section shows that it is feasible to observe a clear and unique signal in the $t\bar{b}$ invariant mass distribution corresponding to the charged Higgs pair creations.Comment: 20 pages, 8 figure

Financial Sector Reforms in Vietnam: Selected Issues and Problems

The purpose of this report is to concentrate on performing in-depth analyses of selected issues of prominence and importance for the future success of the reform process rather than describing the current day-to-day operations and procedures in the financial sector. This eclectic approach implies that other important issues such as the development of a payment system, the state and prospects for the inter-bank markets, and the human capital and organisational issues in the state-owned banks are neglected and/or not analysed in depth. They are, however, omissions due to constraints imposed by funds and time available rather than a failure to comprehend their importance. In this context, the present report should thus be viewed as a first step towards establishing an open dialogue about the nature and speed of the financial sector reforms in Vietnam based on recurrent independent assessments of financial sector issues and problems.Financial Sector Reforms, Vietnam

Factors Affecting Business Angels Investment in Vietnam

The paper aims at investigating and comparing the factors determining investment decisions by business angels (BAs) from the viewpoints of BAs and startups in Vietnam based on a framework synthesized from a literature review and primary data from in-depth interviews conducted with 8 startups and 15 angel investors. The results show that the startups’ founder, working team, financial issues, product and market, and strategy related to exit and the roles of BAs are startup-related factors determining BAs’ investment in Vietnam. For BA-related factors, the BAs’ experience, investment objectives and preferences, and culture are key determinants. The novelty of the paper is to find out the gaps between the perspectives of BAs and startups, and the difference between Vietnamese and foreign BAs’ viewpoints. The finding is that BAs, more strictly than startups, assess their business plan, financial state, product, market, and targeted consumers. Startups neglect the exit strategy and role of BAs in invested startups. In addition, foreign and domestic BAs have different opinions on startups’ market scale, and expectation of profits and BAs’ roles in startups. The paper ends by providing some implications for Vietnamese startups to attract more angel investment, focusing on improving the quality of human resources, developing a profitable, honest, and realistic business plan, and setting up a long-run vision towards the global market. Doi: 10.28991/ESJ-2023-07-02-07 Full Text: PD

Hybrid Magnetic-Semiconductor Oxides Nanomaterial: Green Synthesis and Environmental Catalytic

Semiconductor oxide nanoparticles with various properties are used in applications such as photocatalysis, lithium-ion batteries, antimicrobial materials, magnetic and antibacterial materials, sensors, thermally conductive and anti-ferromagnetic films and photocatalysis. Coprecipitation, sol-gel, electrospray synthesis, laser ablation, hydrothermal and green synthesis methods have been developed for the synthesis of semiconductor oxide nanoparticles. The photocatalytic treatment method is environmentally friendly, thorough, and has high efficiency. Hybrid magnetic-Semiconductor oxide nanoparticles materials are aggregated. This results in the combination of the superparameters of the iron oxide nanosystem and the ability to rapidly adsorb pollutants and separate them from environmental water, solid. This is due to characteristic properties such as low superparameter, low toxicity, low electrical conductivity, and large specific surface area. In addition, biosynthesis has attracted attention because it takes advantage of nonhazardous, environmentally friendly biological systems like bacteria, fungi, leaves, vitamins, and yeast to synthesize metal oxide nanopartilces and combined with sonosumbers to increase the dispersion of the system, reduce the size of the catalytic particles, and reduce the reaction time