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Hong jiao hua jiang lu.
No full text哈葛德[哈格特]原著 ; 林紓, 魏易譯.原書名: BeatriceHagede [Hagete] yuan zhu ; Lin Shu, Wei Yi yi.Yuan shu ming: Beatric
First-Principles Studies of Perpendicular Magnetic Anisotropy and Tunneling Magnetoresistance of Capped Fe/MgO/Fe Tunnel Junctions
No full text近年來，人們發現鐵/鉻/鐵三層材料組成的結構物質具有巨磁阻的現象。巨磁阻為磁阻效應的一種，可以在磁性材料和非磁性材料相間的薄膜層結構中觀察到。這種結構物的電阻值與鐵磁性材料薄膜層的相對磁化方向有關，兩層磁性材料磁化方向相反情況下的電阻值，明顯大於磁化方向相同時的電阻值，使得電阻在微弱的外加磁場下具有很大的變化量。巨磁阻效應已被成功地運用在硬碟生產上，具有重要的商業應用價值，而造成巨磁阻的現象主要是由於鐵磁材料其自旋能帶在費米能級附近分裂的特性，造成自旋態密度在費米能級的差異。由於巨磁阻的發現，用來操縱電子自旋自由度的自旋電子學成為物理上重要的一項領域。
我們利用第一原理計算探討鐵/氧化鎂/鐵穿隧結具有高垂直磁異向能以及高穿隧磁阻的物理原因。在我們的研究中，這是由於在鐵/氧化鎂界面上氧化鎂中的氧與鐵鍵結，導致界面鐵具有一個高自旋極化率的表面態，另外由於在界面上對稱性的破壞，導致界面鐵的能帶由於自旋軌道耦合效應產生分裂的現象，進而發生系統能量對磁矩方向的相關性。第二部分，我們使用第一原理理論計算鐵/氧化鎂/鐵穿隧結在外加覆蓋層(cap)後，對其所造成的物理性質變化。我們分別計算了氧化鎂、釕、鉭，這三種材料並且探討其穿隧磁阻與垂直磁異向性的變化，我們發現這三種材料在與鐵的界面上分別呈現非磁性、鐵磁以及反鐵磁的耦合效應，其中反鐵磁性的鉭對於鐵/氧化鎂/鐵穿隧結的穿隧磁阻具有最好的增強效果，而非磁性絕緣體的氧化鎂對於垂直磁異向能則具有最佳的表現。Recent studies have reported giant magnetoresistance (GMR) in Fe/Cr/Fe trilayer systems. This phenomenon usually occurs in systems consisting of two magnetic electrodes separated by one nonmagnetic metallic layer. Due to the dependence of the electric resistance on the relative magnetization directions in the two magnetic electrodes, the antiparallel magnetization can produce an electric resistance that is stronger than the parallel magnetization. Thus, applying a weak magnetic field can cause a large variation of electric resistance. This dependence of electric resistance on magnetization directions originates from the electronic energy band that splits near the Fermi level in magnetic materials, which results in the different spin density of states at Fermi level. Therefore, the discovery of GMR brought about the spintronics, which exploits the spin-degree of freedom, to be an important branch of physics.
We have performed the first principle calculations to study the physical properties of the Fe/MgO/Fe trilayer system, which has been shown to have the large perpendicular magnetic anisotropy (PMA) and tunneling magnetoresistance (TMR). In the present work, these properties are due to the hybridization between the iron and the oxygen at the Fe/MgO interface, which leads to a surface state with a large spin-polarization. Furthermore, due to the broken symmetry at that interface, if the spin-orbit coupling is taken into account, the energy band of the interfacial Fe would split, leading to an energy dependence of the magnetization direction. In the second part of this thesis, the first principle calculation is performed to study the influences on PMA and TMR when the Fe/MgO/Fe is capped with some materials. Here the MgO, Ta and Ru capping layers are considered, and they reveals nonmagnetic, antiferromagnetic and ferromagnetic coupling to the Fe layer, respectively. In the Fe/MgO/Fe trilayer systems, TMR is usually largest in the Ta-cap systems whereas PMA is usually largest in the MgO-cap systems.CONTENTS
口試委員會審定書 #
Acknowledgements 1
中文摘要 2
ABSTRACT 3
CONTENTS 4
LIST OF FIGURES 6
LIST OF TABLES 11
Chapter 1 Introduction 12
1.1 Overview of spintronics 12
1.2 Research objectives 13
1.3 Thesis outline 14
Chapter 2 Density functional theory 17
2.1 Introduction 17
2.2 Thomas-Fermi theory 19
2.3 Density functional theory 21
2.3.1 Hohenberg-Kohn theorem 21
2.3.2 Kohn-Sham equation 22
2.4 Exchange-correlation potentials 25
2.4.1 Local density approximation (LDA) 25
2.4.2 Generalized gradient approximation (GGA) 27
2.5 Spin polarized calculations 27
2.6 Plane waves and projector augmented wave (PAW) method 29
2.7 Spin-orbit coupling and magnetic anisotropy energy 32
2.8 Two current model and tunneling magnetoresistance 37
Chapter 3 Magnetic properties of the Fe/MgO superlattice 47
3.1 Crystal structure and fundamental properties 47
3.1.1 Introduction and computational details 47
3.1.2 Structure and magnetic properties 49
3.1.3 Variations in thickness of magnetic electrode or insulating layer 52
3.2 Perpendicular magnetic anisotropy 53
3.2.1 Spin-orbit splitting of density of states 53
3.2.2 Spin-orbit splitting of band structure 56
3.3 Tunneling magnetoresistance 58
3.3.1 Electronic density of states 58
Chapter 4 Magnetic properties of the multilayer ultrathin systems 65
4.1 Introduction and computational details 65
4.2 Epitaxial MgO(001) on Fe/MgO/Fe tunnel junctions 67
4.2.1 Electronic density of states 70
4.2.2 Electronic band structure 74
4.3 Epitaxial Ta(001) on Fe/MgO/Fe tunnel junctions 75
4.3.1 Electronic density of states 78
4.3.2 Electronic band structure 81
4.4 Epitaxial Ru(001) on Fe/MgO/Fe tunnel junctions 82
4.4.1 Electronic density of states 85
Chapter 5 Summary 90
REFERENCES 9
The Association between Guideline Adherence for Using Antibiotics Prophylaxis in Cesarean Section and Health Care Outcomes and Expenditure
No full text背景與目的：預防性抗生素的使用已經被證實能夠有效降低手術傷口感染的機會，在過去數十年間也不斷有相關組織發表適當使用預防性抗生素的多種建議。本研究將以2004年發布的「台灣外科手術預防性抗生素使用指引」為依據，針對剖腹產手術進行預防性抗生素使用是否符合指引的相關研究，以了解在2004年國內手術預防性抗生素使用指引發布後，剖腹產手術使用預防性抗生素符合指引的情況，並探討符合預防性抗生素使用指引的產婦是否會有較好的醫療照護結果。
方法：本研究利用2005到2007年全民健保資料庫百萬承保抽樣歸人檔進行次級資料分析，抓取三年間有接受剖腹產手術的產婦共8,518人次為研究對象。以逐步羅吉斯迴歸和逐步複迴歸方法，找出與是否符合指引相關的醫師特性和醫療機構特性，接著探討剖腹產手術預防性抗生素使用是否符合指引和醫療結果的相關。
結果：研究對象8,518人次中，剖腹產預防性抗生素之指引符合率為19.58%，平均每人次使用2.11種抗生素，其中以第一代頭孢子菌類為最常使用的抗生素。研究結果顯示，沒有符合剖腹產預防性抗生素使用指引的產婦出院後七日內發生手術傷口感染的機會較高，且藥費和醫療費用的花費也較多。
結論：剖腹產手術符合預防性抗生素使用指引有較好的醫療結果。雖然剖腹產預防性抗生素的使用指引符合率有逐年上升的現象，然而不論從抗生素種類的選擇、各年符合率或三年總符合率觀察，國內對於預防性抗生素使用指引的遵從度仍有待改善。若相關單位針對醫療提供者特性擬定政策或宣導，應能有效改善國內剖腹產手術預防性抗生素的使用情形。Background and objectives: Using antibiotics prophylaxis has been proven to be effective in reducing the incidence of surgical site infections. Although several guidelines for using antibiotics prophylaxis have been published in past decades, the implementation of these guidelines is unsatisfactory. The main purpose of this study is to understand the status of adherence to guidelines, introduced in 2004, for using antibiotics prophylaxis in cesarean section in Taiwan and to evaluate the association between guideline adherence and health care outcomes.
Method: This study used claims data file of 1 million sampled registry from Taiwan National Health Insurance Research Database. A total of 8,518 cesarean sections from 2005 to 2007 were included in the study. Logistic regression and multiple linear regression were used to test the relationships between guideline adherence and characteristics of health care providers, and to examine the association between guideline adherence and health care outcomes.
Results: Of the 8,518 procedures, the guideline adherence rate was 19.58%; the average use of antibiotics prophylaxis is 2.11 types for each of the births, and the most frequently prescribed antibiotics were first-generation cephalosporins. Births in non-adherence group had significantly higher surgical site infection rate within seven days after discharge and had higher drugs cost and medical expenditure.
Conclusion: The study showed that adherence to guideline in cesarean section had better health care outcomes. Although the guideline adherence of antibiotics prophylaxis is improving in Taiwan, it still has lots of space for improvement. Therefore, the authorities should make policy according to the health care providers’ characteristics to improve the guideline adherence of antibiotics prophylaxis in cesarean section
Ran ci ke zhuan quan yi ce
No full text原著者科南達利 ; 譯述者林紓, 魏易.Translation of: Uncle Bernac.Colophon title.yuan zhu zhe Kenan Dali ; yi shu zhe Lin Shu, Wei Yi
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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