Capacitive Memory Effect of Metal/Semiconductor Junction and Its Application in Superconducting Circuit QED

Department of PhysicsIn the superconducting quantum circuits, a LC oscillator is a main component and Josephson junction gives nonlinearity. Tuning of resonant frequency can be achieved in general by modulating a Josephson inductance of superconducting quantum interference device (SQUID) with magnetic flux. Here, it is proposed to realize tunable capacitor by using metal/semiconductor junction, which can be applied in the superconducting circuit system. Prior to realization of tunable capacitor, the electron transport at metal/semiconductor junctions is studied with two different interfacial layers, Al2O3 and graphene. The effects of interface states on electrical properties of the junction are studied by observing the change in Schottky barrier. First, the Schottky barrier height of Au/Ni/Al2O3/4H-SiC junction increases compared to that of Au/Ni/4H-SiC junction. It is because the electrostatic potential increases due to dipole effect on spontaneous polarization of 4H-SiC as a separation between metal and semiconductor increases. On the other hand, in case of Au/Graphene/4H-SiC junction, the Schottky barrier height decreases due to the presence of graphene. When the metal and graphene are in contact, there is charge transfer through Au/Graphene interface and then the graphene becomes doped. In addition, dipole is formed at the interface between Au and graphene. As a result, the effective work function becomes reduced, so does the Schottky barrier height. Based on the understanding of Schottky junction, tunable capacitor is realized by fabricating Au/Cr/Al2O3/Al/Si junction. With thick Al2O3 film, the electron transfer is blocked for the path between Cr and Al and is allowed only through the Al/Si Schottky junction. Then, the electrons can be captured in the Al floating metal. The amount of charge is dependent on the magnitude of voltage pulses and then discrete capacitance values can be defined. This capacitive memory effect of the tunable capacitor using Schottky junction is expected to be used in the superconducting quantum circuit system in respect that it can change the resonant frequency with discrete capacitance. Among the existing superconducting quantum circuit models, superconducting qubit is the most representative example of LC oscillators. Many superconducting circuit applications have been used to operate the qubits effectively. One promising application in the superconducting circuit QED is Josephson parametric amplifier (JPA). The JPA has been attracted as a device amplifying a signal in quantum-limited regime. It is observed in this dissertation that the JPA and Josephson parametric converter (JPC) which is another kind of JPA can improve the measurement efficiency in superconducting qubit detection. Also, the squeezed state which is another property of the JPA is studied by preparing it with the JPA and amplifying the squeezed signal with the JPC. The phase-dependence of the squeezed state is measured with homodyne setup and is reconstructed visually by using Wigner function. Finally, it is explored to reconstruct quantum state as a form of density matrix by using quantum state tomography (QST) in the superconducting multi-qubit system. It is important to extract quantum state in quantum information processing and necessary to expand the analysis on multi-qubit system. In this dissertation, the QSTs on two and three qubits are studied. A joint qubit readout method is used to measure an ensemble of the system. Also, Z-axis phase gate by using hyperbolic secant pulse is discussed in two qubit system. By using sech pulse, the phase accumulated during microwave-activated phase (MAP) gate can be controlled and eventually compensated. It is expected that the state fidelity can be improved by controlling phase on the qubit.clos

A Case of Epidermolysis Bullosa Simplex (Dowling-Meara 1 Type) in Newborn

Epidermolysis bullosa is a rare genetic skin disease in which skin easily peels off and blisters are formed with mild mechanical trauma. It is classified into simple, borderline, dysmorphic, and mixed type. These four subtypes are further classified according to the location of gene mutation and genetic patterns. Epidermolysis bullosa simplex (EBS) is characterized by separation in the epidermal or subepidermal layer. And it is mostly caused by mutation of keratin 5 (KRT5) and KRT14 genes. Recently, genetic test has become increasingly important for diagnosis, confirming subtypes and genetic counseling. And there are moderate correlation exists between the EBS phenotype and genotype. Here, we report a case of 2-day-old boy with EBS Dowling-Meara type (EBS-DM) diagnosed by mutation analysis in KRT14

Epidural anesthesia for cesarean section in a patient with Marfan syndrome and dural ectasia -A case report-

Pregnancy is considered a period of high risk for cardiovascular complications in patients with Marfan syndrome. Therefore the choice of anesthetic technique for delivery should be focused on minimizing hemodynamic fluctuations, and preferably provide adequate post-operative pain control. For this purpose, neuraxial blocks, such as spinal or epidural anesthesia, may be deemed a safe option. However, dural ectasia is present in 63-92% of patients with Marfan syndrome, and the increased amount of cerebrospinal fluid volume is thought to be one of main reasons for spinal anesthesia failure. We report herein the peri-operative management of a patient with Marfan syndrome and dural ectasia for cesarean section using epidural anesthesia

Schottky Barrier Modulation of Metal/4H-SiC Junction with Thin Interface Spacer Driven by Surface Polarization Charge on 4H-SiC Substrate

The Au/Ni/Al2O3/4H-SiC junction with the Al2O3 film as a thin spacer layer was found to show the electrical characteristics of a typical rectifying Schottky contact, which is considered to be due to the leakiness of the spacer layer. The Schottky barrier of the junction was measured to be higher than an Au/Ni/4H-SiC junction with no spacer layer. It is believed that the negative surface bound charge originating from the spontaneous polarization of 4H-SiC causes the Schottky barrier increase. The use of a thin spacer layer can be an efficient experimental method to modulate Schottky barriers of metal/4H-SiC junctions.open

A Case of Placenta Increta Presenting as Delayed Postabortal Intraperitoneal Bleeding in the First Trimester

Placenta increta is an uncommon and life-threatening complication of pregnancy characterized by complete or partial absence of the decidua basalis. Placenta increta usually presents with vaginal bleeding during difficult placental removal in the third-trimester. Although placenta increta may complicate first and early second-trimester pregnancy loss, the diagnosis can be very difficult during early pregnancy and thus the lesion is difficult to identify. We encountered with a woman who was diagnosed with placenta increta after receiving emergency hysterectomy due to intraperitoneal bleeding 2 months after an uncomplicated dilatation and curettage in the first trimester. Therefore, we report this case with a brief review of the literature

Narcissism and the strategic pursuit of short-term mating : universal links across 11 world regions of the International Sexuality Description Project-2.

Previous studies have documented links between sub-clinical narcissism and the active pursuit of short-term mating strategies (e.g., unrestricted sociosexuality, marital infidelity, mate poaching). Nearly all of these investigations have relied solely on samples from Western cultures. In the current study, responses from a cross-cultural survey of 30,470 people across 53 nations spanning 11 world regions (North America, Central/South America, Northern Europe, Western Europe, Eastern Europe, Southern Europe, Middle East, Africa, Oceania, Southeast Asia, and East Asia) were used to evaluate whether narcissism (as measured by the Narcissistic Personality Inventory; NPI) was universally associated with short-term mating. Results revealed narcissism scores (including two broad factors and seven traditional facets as measured by the NPI) were functionally equivalent across cultures, reliably associating with key sexual outcomes (e.g., more active pursuit of short-term mating, intimate partner violence, and sexual aggression) and sex-related personality traits (e.g., higher extraversion and openness to experience). Whereas some features of personality (e.g., subjective well-being) were universally associated with socially adaptive facets of Narcissism (e.g., self-sufficiency), most indicators of short-term mating (e.g., unrestricted sociosexuality and marital infidelity) were universally associated with the socially maladaptive facets of narcissism (e.g., exploitativeness). Discussion addresses limitations of these cross-culturally universal findings and presents suggestions for future research into revealing the precise psychological features of narcissism that facilitate the strategic pursuit of short-term mating

Narcisismo y búsqueda estratégica del emparejamiento a corto plazo a través de las culturas: Enlaces omnipresentes a través de 11 regiones mundiales del Proyecto de la descripción de la sexualidad internacional 2

Previous studies have documented links between sub-clinical narcissism and the active pursuit of short-term mating strategies (e.g., unrestricted sociosexuality, marital infidelity, mate poaching). Nearly all of these investigations have relied solely on samples from Western cultures. In the current study, responses from a cross-cultural survey of 30,470 people across 53 nations spanning 11 world regions (North America, Central/South America, Northern Europe, Western Europe, Eastern Europe, Southern Europe, Middle East, Africa, Oceania, Southeast Asia, and East Asia) were used to evaluate whether narcissism (as measured by the Narcissistic Personality Inventory; NPI) was universally associated with short-term mating. Results revealed narcissism scores (including two broad factors and seven traditional facets as measured by the NPI) were functionally equivalent across cultures, reliably associating with key sexual outcomes (e.g., more active pursuit of short-term mating, intimate partner violence, and sexual aggression) and sex-related personality traits (e.g., higher extraversion and openness to experience). Whereas some features of personality (e.g., subjective well-being) were universally associated with socially adaptive facets of Narcissism (e.g., self-sufficiency), most indicators of short-term mating (e.g., unrestricted sociosexuality and marital infidelity) were universally associated with the socially maladaptive facets of narcissism (e.g., exploitativeness). Discussion addresses limitations of these cross-culturally universal findings and presents suggestions for future research into revealing the precise psychological features of narcissism that facilitate the strategic pursuit of short-term mating.Estudios previos, en primer lugar a través de las muestras de culturas occidentales, han documentado asociaciones sistemáticas del narcisismo subclínico con múltiples indicadores de estrategias del emparejamiento a corto plazo (p. ej. sociosexualidad ilimitada, infidelidad, caza de pareja). En este estudio se han usado respuestas de la encuesta transcultural de 30.470 personas de 53 naciones de 11 regiones mundiales (América del Norte, América del Sur/América Central, Europa del Norte, Europa del Oeste, Europa del Este, Europa del Sur, Oriente Próximo, África, Asia del Sur/Sudoeste de Asia, Asia del Este y Oceanía) para evaluar si el narcisismo (medido por el Inventario de Personalidad Narcisista; NPI) se asocia panuniversalmente con los indicadores del emparejamiento a corto plazo, tanto en la dirección, como en la intensidad. Los resultados sugieren que el narcisismo (incluidos muchos aspectos suyos medidos por el NPI) tiene las mismas asociaciones básicas con los rasgos de personalidad relacionados con el sexo (p. ej. extraversión alta) y con los resultados sexuales claves (p. ej. búsqueda más activa de las estrategias del emparejamiento a corto plazo) a través de las 11 mayores regiones mundiales del PDSI 2. La discusión se enfoca en las implicaciones y limitaciones del estudio actual

How the COVID-19 pandemic changed travel behaviour? A case study on public bikes in Seoul

This study aims to examine how travel behaviour has changed after the COVID-19 outbreak, specifically focusing on the use of public bikes in Seoul. In January 2020, the Korean government reported its first COVID-19 case and implemented several levels of social distancing measures excluding movement restrictions. These measures, coupled with the fear of infection, resulted in reduced social interactions and, further, changed travel behaviour. Transit usage in Seoul has experienced a significant decline of approximately 25% in 2020 and 2021 compared to the previous two years. However, the use of public bikes continued to rise even during the pandemic, unaffected by the prevalence of the disease. Moreover, there was a doubling of public bike usage during commute hours, implying the potential of public bikes as an alternative travel mode for commute purposes. Our findings suggest that COVID-19 acted as a disruptive shock that prompted changes in travel behaviour. Policymakers should seize this opportunity to promote the wider adoption of cycling, potentially through the development of more efficient and safer infrastructure as well as the implementation of various incentives

Analysis of Eddy-Current Probe Signals in Steam Generator U-Bend Tubes Using the Finite Element Method

To ensure the integrity and safety of steam generator tubes in nuclear power plants, eddy-current testing is periodically employed. Because steam generators are equipped with thousands of thin-walled tubes, the eddy current is tested using a bobbin probe that can be used at high speed. Steam generator heat pipes in nuclear power plants have different sizes and shapes depending on their row number. In particular, heat pipes in the first row are located inside the steam generator and are of the U-bend type because the radius of the curved pipe is the smallest. A steam generator heat pipe has a thickness of about 1 mm, so a geometrical cross-sectional area change may occur due to residual stress when manufacturing the curved pipe. It is difficult to determine an exact shape because the change in cross-sectional area generated during the manufacturing process varies depending on the position of the pipe and the distortion rate. During eddy-current testing (ECT), to ensure the integrity and safety of the steam generator tubes, the shape change of the bend may cause a noise signal, making it difficult to evaluate defects in the pipe. However, the noise signals generated in this situation are difficult to analyze in a real measurement environment, and difficult to verify by producing a mock-up, which complicates distinguishing a noise signal from a defective signal. To solve this problem, various noise signals were obtained using the electromagnetic analysis method of COMSOL Multiphysics, a commercial program based on numerical analysis of the finite element method, to simulate the environment, including the change in cross-sectional area of the heat pipe. When compared to the actual measurement signal, the accuracy of the simulations improved, and various types of noise signals were detected, which may be helpful for accurate evaluations of defects during actual inspections