그래핀 양자점 합성 및 분석과 염증성 장질환에서의 적용

학위논문 (석사) -- 서울대학교 대학원 : 자연과학대학 화학부, 2021. 2. 홍병희.Graphene-based nanomaterials (GBNs) have been applied in the photocatalyst, displays, energy storage devices due to tunable properties and stability. Among them, graphene oxides (GOs) and graphene quantum dots (GQDs) exert high biocompatibility and low toxicity, depending on their characteristics. Besides, due to the superb antioxidant effect, GBNs can scavenge radical oxygen species and have been applied to numerous inflammatory diseases. As the toxicity depends on various factors such as size, surface charge, and concentration, it is essential to control and functionalize for the appropriate usage. Some GBNs emit high intensity of photoluminescence, facilitating their usage in bioimaging. Due to the large surface area, they have also been used as cargo for drug delivery. Recently, GQDs have been proved to interact with the pathogenic protein α-synuclein physically. GQDs degraded preformed fibrils and even inhibited the fibrils' formation when co-incubated with monomers, suggesting a new therapy method for Parkinson's disease. Based on the numerous applications of GQDs on diseases, this dissertation describes the synthesis and characterization of GQDs of two sizes and their applications to ulcerative colitis. Chapter 1 starts by describing the synthesis and characterization of large and small GQDs. Focusing on the biomedical application of GQDs, the antioxidant ability and antibacterial effect of GOs and GQDs are explained. Next, the application of GQDs in various disease models is introduced, including a brief description of ulcerative colitis. As GQDs' biocompatibility and toxicity vary, we stressed that the toxicity differs by physicochemical properties and administration route. Lastly, some surface modification methods, such as conjugating small molecules to GQDs, are explained. Chapter 2 describes the application of GQDs of relatively large size as the alternative therapeutic agent for ulcerative colitis, one of the inflammatory bowel diseases (IBDs). This research was done by collaborating with the college of veterinary medicine, Seoul National University. GQDs were intraperitoneally (i.p.) injected into the DSS (Dextran Sodium Sulfate)-induced colitis model. GQDs alleviated excess inflammation and, through interaction with immune cells, able to restore immune homeostasis. When GQDs were treated to the healthy mice, no significant toxicity was found, with verification of safe clearance through urine. Chapter 3 is about applying small-sized GQDs to the same colitis model through oral delivery. Again, GQDs did not exert significant toxicity despite their different size and administration route. Considering the exposure of GQDs to acidic conditions such as gastric acid, we dispersed GQDs in HCl solution and analyzed the change in characteristics. Overall, GQDs of both sizes and administration routes showed the potential to be used as a treatment for IBDs.그래핀 기반 나노물질은 특성을 조절하기 쉽고 안정하기 때문에 광촉매, 디스플레이, 에너지 저장 장치 등에 적용되었다. 그 중, 산화 그래핀과 그래핀 양자점은 그 특성에 따라 높은 생체적합성과 낮은 독성을 갖는 것으로 알려져 있다. 또한, 이러한 물질들은 매우 뛰어난 항산화 효과를 띄기 때문에 주변의 활성산소 라디칼을 안정화할 수 있음으로 다양한 염증성 질환에 적용되었다. 독성은 크기, 표면 전하, 투여 농도 등에 따라 변하기 때문에 적합한 용도 맞도록 특성을 조절하는 것이 필수적이다. 일부 그래핀 기반 나노물질은 빛을 조사했을 때 매우 높은 강도의 형광을 방출하기 때문에 바이오 이미징 기법에도 적용이 가능하며, 표면적이 넓기 때문에 약물 전달을 위한 매개체로 사용되기도 한다. 최근에 그래핀 양자점은 발병성 단백질인 알파 시뉴클레인과 물리적으로 상호작용하는 것이 밝혀졌는데, 이미 형성된 알파시뉴클레인 섬유를 분해하거나, 섬유화 과정 자체를 억제함으로써 파킨슨병의 새로운 치료제로서의 가능성을 보였다. 이러한 그래핀 양자점의 질병에 치료제로서의 적용 사례를 기반으로 이 논문은 두 가지 크기의 그래핀 양자점의 합성과 분석법과 염증성 장 질환에 치료제로서 적용한 연구에 관해 설명한다. 1장은 두 가지 크기의 그래핀 양자점의 합성과 특성 분석에 대한 설명으로 시작한다. 그래핀 양자점의 생물 의학적 적용에 집중하여, 산화 그래핀과 그래핀 양자점의 항산화 및 항균 효과에 관해 설명하였다. 그 후, 그래핀 양자점이 다양한 질환 모델에 적용된 사례를 소개하며, 이번 연구의 질환 모델인 염증성 장 질환에 대한 설명도 포함하였다. 그래핀 양자점의 생체적합성과 독성은 다양한 요인에 의해 변하기 때문에, 물리 화학적 특성과 투여 경로에 따라 독성 정도가 다른 점을 강조하였다. 2장에서는 염증성 장 질환 중 하나인 궤양성 대장염에 크기가 비교적 큰 그래핀 양자점을 치료 목적으로 적용한 연구에 대한 결과이다. 본 연구는 서울대학교 수의과대학과 공동 연구를 통해 그래핀 기반 나노물질이 면역계 질환에 어떠한 영향을 미치는지에 대해 밝혔다. 그래핀 양자점을 Dextran Sodium Sulfate로 유도한 궤양성 대장염 마우스 모델에 복강 주사로 투여하였다. 그래핀 양자점은 과한 염증반응을 완화하고, 다양한 면역세포와의 상호작용을 통해 면역 항상성을 복구할 수 있었다. 그래핀 양자점을 건강한 마우스에 투여했을 때는, 뚜렷한 독성이 발견되지 않았으며, 소변을 통해 체외로 배출되는 것을 확인하였다. 3장에서는 작은 그래핀 양자점을 같은 궤양성 대장염 마우스 모델에 경구로 투여하여 효능을 확인한 연구의 결과이다. 마찬가지로, 그래핀 양자점은 다른 크기와 투여 경로에도 불구하고 독성을 확인할 수 없었다. 그래핀 양자점을 경구로 전달하면서, 위산에 노출되기 때문에 염산 용액에 그래핀 양자점을 분산시킨 후, 물질의 특성 변화를 분석하였다. 결과적으로 두 가지 크기의 그래핀 양자점을 두 가지 경로로 투여했을 때 모두 염증성 장 질환에서의 효능을 보여 새로운 치료제로서의 가능성을 보였다.Abstract of Dissertation i List of Figures and Tables v Chapter 1. Properties and applications of graphene quantum dots 1 1.1. Synthesis and Characterization of GQDs 1 1.1.1. Synthesis and characterization of large GQDs 1 1.1.2. Synthesis and characterization of small GQDs 3 1.2. Properties of GQDs 4 1.2.1. Antioxidant ability of graphene-based nanomaterials 4 1.2.2. Antibacterial effect of graphene-based nanomaterials 5 1.3. Application of GQDs 6 1.3.1 Biomedical application of GQDs 7 1.3.2 Application of GQDs to ulcerative colitis 8 1.4. Biocompatibility and toxicity of GQDs 9 1.4.1 Toxicity of GQDs depends on various properties 9 1.4.2 Toxicity depending on delivery route 10 1.5. Surface modification and further analysis of GQDs 10 1.5.1. Conjugation of biotin to GQDs 10 1.5.2. Conjugation of rhodamine to GQDs 12 1.6. References 14 Chapter 2. Graphene quantum dots as anti-inflammatory therapy for colitis 17 2.1. Introduction 17 2.2. Results 22 2.3. Discussion 24 2.4. Methods 26 2.5. References 29 Chapter 3. Oral administration of microbiome-friendly graphene quantum dots as therapy for colitis 31 3.1. Introduction 31 3.2. Results 34 3.3. Discussion 51 3.4. Methods 54 3.5. References 62 Appendix 67 Abstract in Korean 69Maste

코로나-19가 캄보디아 교사에게 미친 영향에 관한 사례연구

학위논문(석사) -- 서울대학교대학원 : 사범대학 협동과정 글로벌교육협력전공, 2022. 8. 유성상.1990년대 이후부터 국제사회는 평등하고 양질의 교육을 제공하기 위한 노력을 지속해왔다. 모두를 위한 교육 (EFA), 새천년개발목표 (MDGs), 지속가능개발목표 (SDGs)과 함께 국제사회의 교육 목표가 실천되었다. 그러나 코로나 바이러스감염증-19 (코로나-19)가 전 세계로 퍼지면서 모든 나라의 교육은 부정적인 영향을 받게 되었다. 교육 시스템에 큰 위기가 찾아왔고, 인프라와 재정이 부족한 개발도상국에는 더 큰 위협이 되었다. 이 연구는 캄보디아 교사들은 위기 상황 속에서 어떤 어려움을 겪었고, 어떻게 대우받았는지에 대한 궁금증으로부터 시작되었다. 본 연구에서는 코로나-19로 인한 교사들의 어려움, 교사들에 대한 정부의 지원 등을 통한 이해를 바탕으로 캄보디아 사회 내 교사들의 상황을 보여주고자 한다. 연구의 목적은 위기 상황을 통해 캄보디아 교사가 겪은 어려움과 교육의 질을 위협하는 문제들을 드러내는 것이다. 연구는 사례연구를 통해 진행되었다. 교사 인터뷰와 교육부 공무원 인터뷰를 통해 데이터를 수집하였다. 주된 데이터는 캄보디아 교사의 인터뷰이다. 연구결과는 인터뷰 자료와 보고서들을 통해 구체화하고, 분석되었다. 본 연구를 통해 발견할 수 있는 결과는 다음과 같다. 첫째, 캄보디아 교사들의 공통적인 어려움은 온라인 수업 운영과 적응, 학생 관리, 적절한 인터넷 제공 부족, 과도한 업무가 있다. 코로나 19를 통해 발생한 어려움은 이전보다 교사들에게 더 많은 부담과 스트레스를 부과하였다. 교사들은 이러한 어려움을 극복하기 위해 노력하였다. 둘째, 캄보디아 교사를 위한 예산 지원, 교사 교육, 급여의 지원이 부족했다. 일반 공립학교 교사들을 위한 학습 물품 지원이 부족했다. 교육부에서 교사교육을 제공하였지만 모든 교사들이 참여할 수 없었다. 영어로 의사소통이 가능한 교사들이 교육을 받을 가능성이 많았다. 영어가 가능한 교사들이 다른 교사들에게 알려주는 방식으로 온라인 수업을 위한 교육이 전달되었다. 다수의 교사들에게 기본적인 지원의 필요성이 드러난다. 셋째, 교육부의 지원은 제시된 계획과 차이가 있었다. 교육부는 코로나 대응 계획을 발표해 교사 지원에 대한 강조점을 드러냈다. 계획에 나온 것처럼 교사교육, 온라인 교육지원이 이루어졌다. 그러나 교사들에 대한 공평한 예산 지원, 기기 지원이 부족하였다. 또한, 교사들의 필요를 위한 지원보다는 보건 물품에 대한 지원이 우선순위가 되었다. 따라서 교사 월급의 인상이 이루어지지 않았고, 교사들은 학습 자료와 함께 재정적인 어려움을 겪게 되었다. 캄보디아는 다양한 교육 정책 발표와 함께 교육 위기에 대응을 위한 노력을 하였다. 그러나 정책에서 강조된 만큼 현장에서의 실천은 아직 부족하다. 본 연구의 결과는 캄보디아 교사가 위기 상황 속에서 겪은 어려움을 보여주었다. 캄보디아가 강조하는 교육의 질 제고는 교사를 통해 이루어질 수 있다. 따라서 교사에 대한 사회의 인식 변화와 함께 그들을 위한 적절하고 공평한 지원과 대우가 실천되어야 한다.Since 1990, the international society has continued to improve the conditions of education all around the world. Educational goals of the international society were implemented along with the goals such as the Education for All (EFA), the Millennium Development Goals (MDGs), and the Sustainable Development Goals (SDGs). However, as Coronavirus Disease-19 (COVID-19) spread around the world, education in all countries has been negatively affected. Then there was a crisis in the education system, and it has become a greater threat to developing countries that lack infrastructure and finances. This study begins with the questions about what difficulties Cambodian teachers faced in crisis and how they were treated. It aims to reveal the situation of teachers in Cambodian society based on the understanding of the difficulties of teachers due to COVID-19 and the government's support for teachers. The purpose of the study is to reveal the challenges of Cambodian teachers and problems that threaten the quality education in crisis situations. The research was conducted through case study methods. Data were collected through teacher interviews and public officials of the Ministry of Education. The main data are interviews with Cambodian teachers. The findings were embodied and analyzed with the interviews and reports. The results that can be found through this study are as follows: first, common difficulties for Cambodian teachers include online class operation and adaptation, student management, lack of adequate Internet provision, and excessive work. The difficulties caused by COVID-19 imposed more pressure and stress on teachers than before. Teachers tried to endure these problems. Second, the support for Cambodian teachers was not enough in budget support, teacher education, and salary. The learning materials was insufficient for general public school teachers. Ministry of Education, Youth, and Sport (MoEYS) provided education to teachers, but not all of them could participate. The teachers who are better at English had a higher opportunity of receiving this education program. They taught others how to teach in online class. It shows there is a need to assist the most teachers. Third, there was a gap between the plans and actions of MoEYS. It draws up a plan on how to react to COVID-19, stressing the importance of support for teachers. As shown in the plan, teacher education and online education support were provided. However, there was a lack of budget and devices given. In addition, support for health products has become a priority rather than teachers' needs. Therefore, salaries were not raised, and the teachers had to suffered financial difficulties. Cambodia made efforts to respond to the educational crisis along with the announcement of various policies. However, it is still not practiced as much as emphasized in the policy. The results of this study showed the difficulties of teachers. The development of education emphasized, which Cambodia is aiming to reach, cannot be fulfilled when there is an insufficient support on teachers. Therefore, along with changes in society's perception of teachers, appropriate and equitable support and treatment for them should be practiced.Chapter 1. Introduction 1 1.1. Background 1 1.2. Need of Research 4 1.3. Purpose of Research 5 Chapter 2. Literature Review 7 2.1. Teachers in Developing Countries 7 2.2. Teachers during COVID-19 10 2.3. Overview of the Cambodian Education System 13 2.3.1. Historical Timeline of Cambodia’s Education System 13 2.3.2. Education Policy and System 18 2.3.3. Teacher Training 21 Chapter 3. Research Methodology 22 3.1. Research Methods 22 3.1.1. Researcher Stance 22 3.1.2. Philosophical Framework 23 3.1.3. Case Study 23 3.2. Research Participants 25 3.3. Data Collection 28 3.3.1. Interview 28 3.3.2. Documentation 29 3.4. Data Analysis 29 3.4.1. Analytical Framework 31 3.5. Validity and Reliability 32 3.6. Ethical Consideration 34 Chapter 4. Findings 35 4.1. Teaching and Learning Process 35 4.1.1. Online Teaching Method 35 4.1.2. Management of Students 39 4.1.3. Overwork 44 4.1.4. Teacher Training 45 4.2. Material Resources 52 4.2.1. Teaching and Learning Materials 52 4.2.2. Access to Internet 58 4.3. Human Resources 61 4.3.1. Salary 61 4.4. School Governance 64 4.4.1. School Policy 64 4.4.2. Government Policy 67 Chapter 5. Discussion and Conclusion 69 5.1. More Educational Responsibilities on Teachers 69 5.2. Did Cambodia Education Ensure Quality of Education? 71 5.3. Conclusion 75 References 78 Appendix 86 Abstract in Korean 91석

Clinical Significance of Preoperative Magnetic Resonance Imaging in Staging of Rectal Cancer

Rectal cancer carries poor prognosis because of metastasis and local recurrence. Local recurrence has a profound effect on morbidity and quality of life. Randomized trials have proven that neoadjuvant treatment can significantly reduce local recurrence rate in some selected cases of advanced rectal cancer. Therefore, preoperative staging of rectal cancer has an important impact on treatment plan. Two main factors in predicting the local recurrence are known as the circumferential resection margin (CRM) and the nodal status. Recently, high-resolution magnetic resonance imaging (MRI) is regarded as a superior modality in the preoperative assessment of CRM with high accuracy and reproducibility. However, the results of imaging in predicting of nodal involvement are not satisfactory. In order to increase the accuracy of preoperative nodal staging, several efforts were done to evaluate lymph node by MRI or by pelvic MRI using lymph node-specific contrast agent (ultrasmall superparamagnetic iron oxide, USPIO). In this review, the role of MRI in preoperative evaluation of rectal cancer will be discussed.ope

Fostering Public Service Motivation in Organizational Settings

학위논문 (석사)-- 서울대학교 행정대학원 : 행정학과(정책학전공), 2014. 2. 임도빈.Public Service Motivation (PSM) is one of the vintage topics in public administration field that has received great amount of attention from scholars around the world. A number of studies revealed the various relationships between PSM and various outcomes such as improved performance, job satisfaction, organizational commitment and decreased turnover intention and whistle-blowing. Since PSM is correlated with many positive outcomes in organizations, one can ask how we can enhance and maintain the level of PSM of individual employees. The main purpose of this study is to suggest what managers can consider doing in order to foster PSM in their organizations by analyzing the relationship between PSM and some factors we often find in organizational settings. Using survey data of the Korean public officials in various sectors of central government, this study attempts to find out if leadership (transformational leadership in particular), merit-based system, and red tape have significant influence of individuals' level of PSM. The result shows that the transformational leadership is positively related with the level of PSM. However, unlike many previous researches, this study with Korean public officials shows that red tape does not have significant relationship with their level of PSM while the merit-based reward system has significant positive influence on employees level of PSM.I. Introduction 1. Research Background 2. Scope of the study II. Theoretical Frame work and Literature Reviews 1. Public Service Motivation i. Definition ii. Previous Researches 2. Transformational Leadership i. Definition ii. Previous Researches 3. Merit-based Reward System i. Definition ii. Previous Researches 4. Red tape i. Definition ii. Previous Researches III. Research Design and Method 1. Research Question and Hypothesis 2. Variables i. Dependent Variable ii. Independent Variable iii. Control Variable 3. Data 4. Method IV. Result and Analysis 1. Descriptive Statistics i. Sample ii. Factor Analysis iii. Reliability 2. Multiple Regression Analysis i. Correlation ii. Multicollinearity iii. Hypothesis Test V. Conclusion 1. Summary 2. Discussion 3. Limitation and Policy Implication VI. ReferenceMaste

펨토셀 네트워크에서 자원 관리에 관한 연구

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2014. 8. 전화숙.모바일 트래픽 수요가 폭발적으로 증가함에 따라 실내 사용자들에게 낮은 비용으로 고품질의 데이터 서비스를 제공할 수 있는 펨토셀이 주목을 받고 있다. 본 논문에서는 펨토셀이 기존의 매크로셀 위에 구축된 two-tier 펨토셀 네트워크에서 주파수 효율과 에너지 효율 향상을 위한 두 가지 자원 관리 기법을 제안하였다. 먼저, 주파수 효율을 향상시키기 위한 펨토셀들과 중첩 매크로셀 사이의 하향 링크 무선 자원 분할(radio resource partitioning) 기법을 설계하였다. 제안하는 무선 자원 분할 기법에서는 모바일 데이터 폭증 문제에 대한 또 다른 해결 방안인 분할 주파수 재사용(fractional frequency reuse, FFR) 기술이 적용된 매크로셀 네트워크를 고려하였다. FFR 구조에서 매크로셀의 주파수 대역은 다수의 주파수 분할들(frequency partitions, FPs)로 나누어지고, FP마다 다른 전송 전력이 할당된다. 제안한 기법에서 각 FP는 다시 매크로 전용 부분(macro-dedicated portion), 공용 부분(shared portion), 그리고 펨토 전용 부분(femto-dedicated portion)으로 구성되고, 이 세 부분의 비율은 FP마다 다르게 설정된다. 제안하는 기법은 최적화 방식을 이용하여 주파수 효율을 최대화하도록 각 FP 내 자원 분할 비율을 결정한다. 다음으로, 공항 및 쇼핑몰과 같이 사용자들이 밀집된 공공장소에 많은 수의 펨토 기지국들이 설치된 개방형 펨토셀 네트워크에서 에너지 효율을 향상시키기 위한 자원 관리 기법을 제안하였다. 고려하는 펨토셀 네트워크에서는 펨토 기지국들이 최대 트래픽 부하를 지원하기 위해 높은 밀도로 설치되기 때문에 대부분의 동작 시간 동안 펨토셀들은 무선 자원을 충분히 활용하지 않는다. 따라서 사용자들의 셀 접속을 적절히 조정하여 가능한 적은 펨토 기지국들을 활성화시키고 그 이외의 펨토 기지국들을 수면 모드(sleep mode)로 동작시킨다면 해당 펨토셀 설치 지역에서의 네트워크 에너지 효율을 크게 향상시킬 수 있을 것이다. 따라서 본 논문에서는 에너지 효율을 향상시키기 위해 펨토 기지국의 동작 모드(active 또는 sleep)와 사용자들의 셀 접속을 동시에 결정하는 펨토 기지국 동작 모드 결정 및 사용자 접속 (femto BS sleep decision and user association, SDUA) 기법을 설계하였다. 제안하는 기법에서 SDUA 문제는 사용자들에게 만족할 만한 서비스를 제공하면서 전체 에너지 소모를 최소로 하는 것을 목표로 하는 최적화 문제로 정식화되었다. SDUA 문제는 기지국의 동작 모드와 사용자의 셀 접속이 상호 영향을 주어서 계산 복잡도가 높으므로 본 논문에서는 먼저 활성화 펨토 기지국들의 집합이 주어진 상태에서 최적의 사용자 접속(user association, UA) 문제를 풀고, 각기 다른 집합들에 대해서 최적화 UA를 반복적으로 수행함으로써 최선의 활성화 펨토 기지국 집합을 찾는 휴리스틱 알고리즘을 설계하였다. 제안하는 두 자원 관리 기법들이 각각 주파수 효율과 에너지 효율에 대해서 기존의 기법들보다 우수한 성능을 보임을 시뮬레이션을 통해 확인하였다.Femtocell has received wide attention as a promising solution to meet explosively increasing traffic demand in cellular networks, since it can provide high quality data services to indoor users at low cost. In this thesis, we study resource management in two-tier femtocell networks where the femtocells are underlaid by macrocells, from two different aspects: spectral effciency and energy eciency. First, we design a downlink radio resource partitioning scheme between femtocells and their overlaid macrocell to enhance the spectral eciency. We consider that the overlaid macrocell network adopts the fractional frequency reuse (FFR) techniques, which is also one of solutions to the mobile data surge problem. With FFR, the frequency band of a macrocell is divided into several frequency partitions (FPs) and the transmission power levels assigned to FPs differ from each other. With the proposed scheme, every FP is divided into the macro-dedicated, the shared, and the femto-dedicated portions. The ratio of these three portions is different for each FP. We suggest a method to determine a proper ratio of portions in each FP, by using optimization approach. Next, we propose a scheme to enhance the energy efficiency in open access femtocell networks where many femto base stations (BSs) are deployed in a large public area such as office building, shopping mall, etc. In those areas, the femtocells are overlapped and underutilized during most of the operation time because femto BSs are densely deployed to support the peak traffic load. So, if we properly coordinate the user association with cells and put the femto BSs having no associated users to sleep, the network energy efficiency in the femtocell deployment area can be greatly enhanced. Therefore, we propose a femto BS sleep decision and user association (SDUA) scheme that jointly determines the operation modes (i.e., active or sleep) of femto BSs and the association between users and the active BSs. The SDUA problem is formulated as an optimization problem that aims at minimizing the total energy consumption while providing the satisfied service to users. Since the SDUA problem is too complicated to be solved, we first solve the optimal user association (UA) problem for given set of active femto BSs and then design a heuristic algorithm that finds the best set of active femto BSs by iteratively performing the optimal UA with each different set. By simulation, it is shown that the proposed schemes achieve their design goals properly and outperform existing schemes.1 Introduction 1.1 Background and Motivation 1.2 Proposed Resource Management Schemes 1.2.1 Radio Resource Partitioning Scheme for Spectral Efficiency Enhancement 1.2.2 Base Station Sleep Management Scheme for Energy Efficiency Enhancement 1.3 Organization 2 Radio Resource Partitioning Scheme for Spectral Efficiency Enhancement 2.1 System Model 2.1.1 Heterogeneous Network 2.1.2 Capacity Model 2.2 Proposed Downlink Radio Resource Partitioning Scheme 2.2.1 Macrocell Protection Mechanism 2.2.2 Determination of Dedicated Portion for Macrocell/Femtocell Users 2.3 Capacity Estimation 2.3.1 Achievable Macrosector Capacity 2.3.2 Achievable Femtocell Capacities 2.3.3 SHG Availability of Femtocell 3 Base Station Sleep Management Scheme for Energy Efficiency Enhancement 3.1 System Model 3.1.1 Open Access Femtocell Network 3.1.2 Operation Modes and Power Consumption of a BS 3.1.3 Energy Efficiency 3.2 Analysis on Energy Efficiency 3.2.1 Mathematical Model 3.2.2 Derivation of Energy Efficiency 3.2.3 Numerical Results and Discussion 3.3 Proposed Femto BS Sleep Decision and User Association (SDUA)Scheme 3.3.1 Problem Formulation 3.3.2 Solution Approach 3.3.3 Implementation Example of SIR Estimation 4 Performance Evaluation 4.1 Radio Resource Partitioning Scheme 4.1.1 Simulation Model 4.1.2 Simulation Results 4.2 Base Station Sleep Management Scheme 4.2.1 Simulation Model 4.2.2 Simulation Results 5 Conclusion Bibliography AbstractDocto

Changes of Coregulators, MAP Kinase Activity and p27/kip1 with Estrogen or Antiestrogen Treatment in Breast Cancer Cell Line

PURPOSE: Estrogen, various polypeptide hormones and growth factors are associated with the development and progression of breast cancer. Coregulatory proteins are also associated with estrogen receptor (ER) transcriptional activity and tamoxifen resistance. Therefore, it is necessary to investigate the change of coregulator mRNAs and various cell proliferation proteins and cell cycle-related proteins after treatment with estrogen or antiestrogen. METHODS: MCF-7 cells were maintained in dextran-coated charcoal stripped 10% Dulbecco's Modified Eagle Medium (DMEM). To measure the change of the coactivators' (src-1, P/CAF, CBP, AIB1) mRNAs and corepressors' (SMRT, N-coR) mRNAs, multiple PCR was carried out using specific primers. In addition, intracellular proteins related to cell proliferation and cell cycle regulation were measured by performing Western blotting after treatment with estrogen or tamoxifen. The change of mitogen activated protein kinases was also measured by performing Western after tamoxifen treatment for 4 weeks. RESULTS: Coactivator mRNAs expression rapidly decreased in 15 min after estrogen treatment but this recovered to the initial level in 3 hr. The pattern was similar for the case of tamoxifen treatment. Corepressor mRNAs expression rapidly decreased in 15 min after estrogen treatment and it remained at a lower level until 24 hr after estrogen treatment. With tamoxifen treatment, the initial response was similar to the cases of estrogen treatment, but the xpression gradually increased 3 hr after tamoxifen treatment. Treatment of estrogen induced intracellular concentrations of c-myc and Ki-67 and it increased nuclear translocation of NF-kappaB and phosphor-ERK and it decreased the intracellular cell cycle suppressor p27/kip1. Tamoxifen treatment increased nuclear p27/kip1 but it decreased c-myc, NF-kappaB and phosphor-ERK. Long-term (4 weeks) treatment of tamoxifen was associated with decrease of activated ERK and p38 but there was no change in phospho-Akt level. CONCLUSION: Estrogen induced cell proliferation and the survival pathway-related factors, but it decreased the cell cycle suppressor p27/kip1. Long-term treatment with antiestrogen tamoxifen might decrease the MAPK activities in ERalpha-expressing tumor cells.ope

Apparent diffusion coefficient of hepatocellular carcinoma on diffusion-weighted imaging: Histopathologic tumor grade versus arterial vascularity during dynamic magnetic resonance imaging

OBJECTIVES: Apparent diffusion coefficient (ADC) has been suggested to reflect the tumor grades of hepatocellular carcinomas (HCCs); i.e., it can be used as a biomarker to predict the patients' prognosis. To verify its feasibility as a biomarker, the present study sought to determine how the ADC values of HCC are affected by a tumor's histopathologic grade and arterial vascularity. MATERIALS AND METHODS: From 131 consecutive patients, 141 surgically resected HCCs (16 well-differentiated [wd-HCCs], 83 moderately-differentiated [md-HCCs], and 42 poorly-differentiated HCCs [pd-HCCs]) were subjected to a comparison of the tumors' arterial vascularity (non-, slightly-, or markedly-hypervascular) determined on dynamic magnetic resonance imaging (MRI) and the ADC was measured retrospectively. RESULTS: The pd-HCCs (1.05+/-0.16 x 10-3 mm2/s) had a significantly lower ADC than md-HCCs (1.16+/-0.21 x 10-3 mm2/s; p = 0.010), but there was no significant difference compared to wd-HCCs (1.11+/-0.18 x 10-3 mm2/s; p = 0.968). The mean ADC was significantly higher in markedly hypervascular lesions (1.20+/-0.20 x 10-3 mm2/s) than in nonhypervascular lesions (0.95+/-0.14 x 10-3mm2/s; p<0.001) or slightly hypervascular lesions (1.04+/-0.15 x 10-3mm2/s; p<0.001). The ADC values and arterial vascularity were significantly correlated in wd-HCCs (p = 0.005) and md-HCCs (p<0.001). The mean ADC of pd-HCCs was significantly lower than those of other lesions, even in the markedly hypervascular lesion subgroup (p = 0.020). CONCLUSION: Although pd-HCC constantly shows low ADCs regardless of arterial vascularities, ADCs cannot stably stratify histopathologic tumor grades due to the variable features of wd-HCCs; and the ADC should be used with caution as a tumor biomarker of HCC.ope

Prognostic value of gallbladder wall thickening in patients with acute hepatitis A.

PURPOSE: To investigate the clinical significance of gallbladder (GB) wall thickening frequently observed in patients with acute hepatitis A. METHODS: A total of 328 consecutive patients who were diagnosed with acute hepatitis A and underwent abdominal ultrasonography were enrolled retrospectively. Patients were divided into two groups: GB wall thickening (≥3 mm, group A) and no thickening (group B). Group A was subdivided into two subgroups (GB wall thickening of ≥10 mm, group A-1 and ≥3 mm to <10 mm, group A-2). The laboratory results related to liver function, hospitalization duration, and time to normalization of liver function were compared between the groups. RESULTS: A total of 230 patients showed GB wall thickening (group A). Besides gamma-glutamyl transpeptidase and alkaline phosphatase, all laboratory results of group A were significantly higher than those of group B (P<0.05). Compared with group B, the hospitalization duration and the time to normalization of liver function were significantly longer in group A (P<0.05). Group A-1 included 146 patients and group A-2 included 84 patients. No significant differences in laboratory results, hospitalization duration, and time to normalization of liver function were found between the two subgroups. In the multivariate logistic regression analysis, serum alanine transaminase, total bilirubin and albumin levels, and hospitalization duration were significantly associated with GB wall thickening in patients with hepatitis A. CONCLUSION: The presence of GB wall thickening in patients with acute hepatitis A suggests a poorer prognosis irrespective of the degree of GB wall thickening or the degree of liver enzyme elevation.ope

뇌혈관 컴퓨터단층촬영 조영술에서의 감쇄 기반 자동 관전압 선택 알고리즘: 방사선 조사와 영상 품질에 미치는 영향

Objective: To investigate the feasibility of using the attenuation-based automatic tube potential selection (ATPS) algorithm for cerebral computed tomography angiography (CTA) and to assess radiation dose, vascular attenuation, and image quality compared to a conventional fixed 120-kVp protocol. Materials and Methods: Among 36 volunteers for cerebral CTA, a total of 18 were scanned with fixed 120 kVp and 140 effective mAs using automatic tube current modulation. The other 18 were scanned with an ATPS algorithm. Radiation doses, attenuation, contrast-to-noise ratio (CNR) of the cerebral arteries, subjective scores for arterial attenuation, edge sharpness of the artery, visibility of small arteries, venous contamination, image noise, and overall image quality were compared between the groups. Results: The volume CT dose index and effective dose of the ATPS group were lower than those of the fixed 120-kVp group. The ATPS group had significantly higher arterial attenuation and no significant difference in CNR, compared with the fixed 120-kVp. The ATPS group had higher subjective scores for arterial attenuation, edge sharpness of the artery, visibility of small arteries, and overall image quality. Conclusion: The ATPS algorithm for the cerebral CTA reduced radiation dose by 43% while maintaining image quality and improved the attenuation of cerebral arteries by selecting lower tube potential.ope

Clinicopathologic Characteristics of Apocrine Breast Carcinoma

Purpose: Apocrine carcinoma is a rare type of breast carcinoma, which has not been fully investigated. The aim of this study was to review clinicopathological features of apocrine carcinoma of the breast and to determine if there are some characteristics different from invasive ductal carcinoma. Methods: There were 4,064 breast cancer patients who had been managed in the Department of Surgery of Yonsei University College of Medicine from January 1997 to January 2008. Out of the patients, 16 patients with apocrine carcinoma and 2,997 patients with invasive ductal carcinoma were analyzed retrospectively. Results: The incidence of apocrine carcinoma was 0.4%. Most of the clinicopathologic features of apocrine carcinoma were similar to those of invasive ductal carcinoma. The percentage of estrogen receptor (ER) positivity and progesterone receptor (PR) positivity of apocrine carcinoma were all 12.5%. And the percentage of ER positivity and PR positivity of invasive ductal carcinoma were 64.2% and 55.2% respectively. Androgen receptor was only examined for eleven patients out of the 16 patients with apocrine carcinoma and the result were all positive. Conclusion: Apocrine carcinoma is also a rare disease in Korea. When compared with invasive ductal carcinoma, the disease did not appear to show any other significant difference in clinicopathologic characteristics but the percentages of ER and PR positivity of apocrine carcinoma seemed lower than those of invasive ductal carcinoma.ope