1,720,986 research outputs found
Detection of Copper Ions Using Copper/Silver Nanoclusters
No full text本論文利用以DNA為模板所合成之銅銀奈米團簇 (DNA-Cu/Ag nanoclusters, DNA-Cu/Ag NCs) 配合巰基丙酸 (3-mercaptopropionic acid, MPA) 發展出一種簡單、免標定(label-free) 之銅離子螢光探針。其偵測機制是由於MPA與DNA-Cu/Ag NCs上之金屬離子作用導致團簇的構形瓦解，使螢光消光；此時在有額外銅離子存在下，MPA先和銅離子生成錯合物並進一步被氧化成雙硫形式 (disulfide)，隨著銅離子濃度增加，使未作用的MPA濃度下降，導致DNA-Cu/Ag NCs螢光被消光的程度會下降，因此螢光強度會隨著銅離子濃度增加而增強。在最佳化的反應條件，其偵測極限 (limit of detection，LOD) 為3.5 nM，線性範圍5-200 nM (R2 = 0.988)。此方法對於銅離子具有極高的選擇性，為其他金屬離子的2300倍。將此方法應用於偵測土壤樣品中銅離子濃度，所測得濃度為2.60 (± 0.23) μM，與利用感應耦合電漿質譜分析儀 (Inductively coupled plasma mass spectrometry; ICP-MS) 分析結果一致，顯示此方法適合用於環境樣品的分析。This thesis focuses on devoloping a simple and homogeneous fluorescence assay—comprising 3-mercaptopropionic acid (MPA) with DNA-Cu/Ag nanoclusters (NCs) in aqueous solution—for the detection of Cu2+ ions. The sensing mechanism is based on the suppression of MPA induced fluorescence quenching of the DNA-Cu/Ag NCs by Cu2+. MPA-induced fluorescence quenching is due to changes in the DNA conformation as a result of the interactions between MPA and Cu/Ag clusters. The MPA-induced fluorescence quenching followed a typical characteristic of a Stern-Volmer plot and followed a static quenching mechanism. The presence of Cu2+ resulted in the oxidation of MPA to form disulfide, leading to suppression of the MPA-induced fluorescence quenching. The fluorescence of the DNA-Cu/Ag NCs in the presence of MPA increased upon increasing the concentration of Cu2+ over the range 5-200 nM. The DNA-Cu/Ag NC probe provided the limit of detection at a signal-to-noise of 3 of 2.7 nM for Cu2+ ions, with high selectivity (at least 2300-folds over tested metal ions). The practicality of this approach has been validated by the analyses of Montana soil and water samples (3 replicate measurements), showing the potential of the probe for detection of Cu2+ ions in environmental samples
The effect of larval competition on adult weight and its mechanism in Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)
No full text四紋豆象幼蟲為內食性昆蟲，幼蟲在羽化之前無法自由離開寄主豆。前人研究顯示，隨著豆內的幼蟲數增加，資源的競爭程度增加，經常導致成蟲的平均體重顯著下降的現象。然而，本研究卻發現，當以小型綠豆為寄主，幼蟲期遭遇競爭的成蟲，其平均體重顯著較幼蟲期沒有競爭的成蟲為重。另以食物及空間相對較多的大型綠豆為寄主，卻沒有發現體重顯著變大的現象。顯示寄主大小是造成競爭後羽化體重變大的重要條件。本文旨在探討幼蟲競爭導致羽化體重增加的原因。首先透過模擬，檢驗體重上升的原因，是否完全源自較輕個體在競爭中被淘汰之故。結果顯示，模擬後獲得的體重分布，與實際的分布並不相符。顯示對體重的選汰不是導致體重上升的唯一原因。此外，具有競爭經歷的幼蟲,其發育期並無延長的現象。因此，延長發育期以增加取食量不是體重上升的原因。我們進一步假設，取食對手是造成羽化體重變大的原因。因此對三卵豆進行解剖。結果顯示，豆內幼蟲有互咬的行為，且在不完整的屍體上發現疑似被取食的痕跡，加上蟲屍不見的比例隨著時間上升。說明同類相食的現象存在於四紋豆象幼蟲，取食同類是獲得額外體重的可能來源。再者，經由測量幼蟲取食量的試驗，顯示三隻幼蟲處理下幼蟲取食量顯著大於一隻幼蟲處理者。此結果說明，優勢幼蟲藉由增加取食量，進而提高平均羽化體重的可能無法排除，其可能性猶待進一步的檢驗。此外，前人於四紋豆象South India品系之中，曾發現幼蟲能以取食所發出的震動抑制同種幼蟲的進食，進而決定幼蟲競爭的勝負。然而，本試驗結果顯示，所使用的4C6-4品系，同種幼蟲發出的取食震動，對其體重的效應並不顯著。Larvae of the seed beetle Callosobruchus maculatus develop inside the seeds of their host plants, and are incapable of moving between seeds. Many studies reported a reduction of adult weight as larval density increases due to resource shortage. However, I observed a different trend that larval competition led to an increase of adult weight when the host size was small. The phenomenon disappeared when host size was large, indicating that host size was a crucial factor for the trend. In this study, I tried to answer how adult weight increases under larval competition. Since egg-to-adult development was not prolonged under larval competition, increased feeding period via longer development is not the cause of the greater adult weight. Furthermore, the proportion of large individuals of the observed distribution at high larval density was significantly higher than that of a simulated distribution where small individuals were eliminated by an imaginary selection. Thus, there must be other causes leading to greater adult weight besides selection on body size. I further hypothesized that cannibalism increases adult weight under larval competition. By dissecting beans with 3 larvae at regular intervals, I found interference behavior and the evidence of cannibalism in larvae of C. maculatus, the finding potentially supporting the cannibalism hypothesis because conspesifics could be extra food source when bean resource was limited. Nevertheless, dominant larvae could also gain more weight by raising total food consumption in response to competition. In this study, the total consumption at high larval density was significantly higher than that at low larval density, indicating the possibility of increased efficiency. Further investigation is required. Finally, a previous study demonstrated that South India strain of C. maculatus could emit feeding vibration at larval stage to affect conspesifics weight. But, no indication in my experiment showed feeding vibration of 4C6-4 strain affected adult weight.ABSTRACT………………………………………………………1
CHINESE ABSTRACT………………….……………………………3
LIST OF FIGURES……………………………………………………6
LIST OF TABLES…………………………………………………7
INTRODUCTION…………………………………………………8
MATERIALS AND METHODS
The origin of experimental population and stock maintenance…12
Experiment 1--The effect of larval density on adult weight and development time in small and large mung bean………12
Experiment 2--Investigation on cannibalism by dissecting beans with 3 larvae at regular interval……………… ……14
Experiment 3--The relationship between adult weight and total food consumption at density of one larva and three larvae……………………………………………………………15
Experiment 4--The effect of feeding vibration on adult weight……16
RESULTS
Experiment 1--The effect of larval density on adult weight and development time in small and large mung bean…………18
Experiment 2--Investigation on cannibalism by dissecting beans with 3 larvae at regular interval………………………30
Experiment 3-- The relationship between adult weight and total food consumption at density of one larva and three larvae……………………………………………………………36
Experiment 4--The effect of feeding vibration on adult weight……39
DISCUSSION…………………………………………………………42
REFERENCES..………………………………………………………48
ACKNOWLDGEMENT………………………………………………5
The Prospect of P2P Lending Development in Taiwan
No full textP2P借貸（Peer to Peer Lending）是指將有閒錢的投資人和需要資金的借款者，利用網路平台媒合，實現直接借貸。臺灣目前尚未開放P2P，但互聯網金融是未來的趨勢，臺灣未來有一天可能會開放P2P，因此本文便以四種關係人（投資者、借款者、銀行、政府）的角度探討純資訊仲介的P2P業者是否適合在臺灣發展。 從本文分析來看，純資訊中介模式的P2P業者不適合在台灣發展。從投資者角度來看，P2P雖然能給投資者比定存更高的報酬，但投資者要自行承擔違約風險，也會面對許多可能造成P2P平台倒閉的風險，這麼高的風險可能會使投資者望而卻步。從借款者角度來看，P2P在臺灣能為借款者帶來的利益不大，可能無法吸引夠多的借款者來平台借款。從銀行角度來看，P2P業者加入會使得銀行和P2P業者承做放貸業務都很有壓力。且銀行自己經營P2P會有更多優勢，非銀行經營的P2P相較之下就較沒競爭力。從政府角度來看，目前引進P2P會消耗太多成本，導致政府近期對於開放P2P的態度消極。因此總體而言，本文認為從目前臺灣的環境來看，純資訊中介P2P業者不適合在臺灣發展。Peer-to-peer lending (P2P) is the practice of lending money to unrelated individuals online without going through a traditional financial intermediary such as a bank. P2P lending isn’t allowed in Taiwan yet; however, internet finance is the trend of future. Taiwan may open the license of P2P in the future. Therefore, this thesis analyzes if it is suitable for pure P2P platforms to develop in Taiwan by four perspectives (investors, lenders, banks, government). By the analysis of this thesis, P2P companies are not suitable to develop in Taiwan. As for investors, although investors can get higher returns from P2P, they also need to bear the default risk, and consider the risks that may cause the collapse of P2P platforms. With all these high risks, investors may not invest in P2P. As for borrowers, P2P benefits borrowers little in Taiwan. Therefore, there may be not enough borrowers to borrow from P2P platforms. From the perspective of banks, if P2P develops in Taiwan will make both banks and P2P platforms do credit business under great pressure. Besides, banks have more advantages to run P2P platforms. P2P companies may be unable to compete with P2P platforms ran by banks. From the perspective of government, opening the license of P2P consumes too many costs for now. Therefore, government tends not to open the license in a short term. Overall, from the analysis of this thesis, pure P2P platforms are not suitable to develop in Taiwan in the short term
Word-of-Mouth Effects on Hospital Choice and Moderator Variables
No full text相較於廣告或其他促銷活動，口碑為商業性較低的溝通行為，口碑提供者較不會因為傳播口碑而得到任何利益，因此民眾會藉由口碑來決定是否購買產品或服務，而民眾對於醫療服務結果不確定性更大，於是口碑為民眾選擇就診醫院重要的影響因素，但針對口碑與民眾就醫選擇的影響卻少有去探討，因此本研究主要探討口碑對民眾就醫選擇的影響，以及專業程度、關係強度、知覺風險與服務多重選擇這些不同調節因素下，口碑對民眾就醫選擇的影響程度。
本研究藉由問卷調查門診的民眾其在選擇就診醫院前，接受口碑的情況，並且受口碑影響的程度，而口碑分為口碑積極度、正向口碑與負向口碑三個構面，提供者專業程度、接受者專業程度、關係強度、知覺風險與服務多重選擇為調節變項，依變項為影響就醫選擇的程度，結果顯示口碑積極度、正向口碑與負向口碑皆會對影響就醫選擇的程度有正向影響，而不同情境因素下，口碑資訊對民眾就醫選擇影響程度的情形為：
1. 當提供者專業程度愈高，對口碑積極度與正向口碑對就醫選擇影響程度的
調節效果愈小。
2. 當關係強度愈高，對口碑資訊對影響就醫選擇程度的調節效果愈小。
3. 當財務風險愈高，對口碑積極度影響就醫選擇程度的調節效果愈小。
4. 當民眾可選擇醫院愈多以及較少能選擇時，對口碑資訊對影響就醫選擇程度的
調節效果愈高。
即使研究結果顯示愈高的提供者專業程度、關係強度與財務風險，其對就醫選擇的調節效果是較小的，但同樣也發現其對口碑對就醫選擇的影響程度依然是較高的，表示對醫院管理者而言，須重視在高專業程度口碑提供者、高關係強度、高知覺風險對就醫選擇的影響效果，以及著重特色醫療的口碑傳播。Word-of-mouth (WOM) is a person-to-person communication without commercial bias. Sender will not get benefit from communicating WOM; therefore people who make purchase decision will be affected by WOM. Moreover people perceive more uncertain on health care service, and WOM becomes an important source of information to selecting health care providers. This article studies the effects of WOM in hospital choice and the factors that influence WOM effect. The factors as a moderator variables include senders’ and receiver’s expertise, tie strength, perceived risk and multiple choice.
The study examines finding from 155 outpatients of medical center. The dimension of WOM information includes WOM activity and WOM praise, and the independence variable is the effect of WOM on hospital choice. The moderator variables include senders’ and receiver’s expertise, tie strength, perceived risk and multiple choice. The results are drawn below:
1. The more WOM information, the greater effect of WOM on
hospital choice.
2. When the senders’ expertise is high, the moderator effect
of WOM activity / positive WOM on hospital choice is low.
3. When the tie strength is high, the moderator effect of
WOM information on hospital choice is low.
4. When the financial risk is high, the moderator effect of
WOM activity on hospital choice is low.
5. When the amount of hospital can be chosen are many or
only one, the moderator effect of WOM activity on
hospital choice is high
Detection of Copper Ions Through Recovery of the Fluorescence of DNA-Templated Copper/Silver Nanoclusters in the Presence of Mercaptopropionic Acid
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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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