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Master of Science

No / D-amino acids are useful building blocks for de novo peptide design and they play a role in aging-related diseases associated with gradual protein racemization. For amino acids with achiral side chains, one should be able to presume that the conformational propensities of L- and D-amino acids are a reflection of one another due to the straightforward geometric inversion at the Cα atom. However, this presumption does not account for the directionality of the backbone dipole and the inverted propensities have never been definitively confirmed in this context. Furthermore, there is little known of how alternative side chain chirality affects the backbone conformations of isoleucine and threonine. Using a GGXGG host-guest pentapeptide system, we have completed exhaustive sampling of the conformational propensities of the D-amino acids, including D-allo-isoleucine and D-allo-threonine, using atomistic molecular dynamics simulations. Comparison of these simulations with the same systems hosting the cognate L-amino acids verifies that the intrinsic backbone conformational propensities of the D-amino acids are the inverse of their cognate L-enantiomers. Where amino acids have a chiral center in their side chain (Thr, Ile) the β-configuration affects the backbone sampling, which in turn can confer different biological properties. / NIH

The movement patterns, range areas and energetics of canvasbacks (Aythya valisineria) wintering in the upper Chesapeake Bay, Maryland, were investigated. Eighty-seven juvenile female canvasbacks were radio-tracked between 30 December 1988 and 25 March 1989. Diurnal time and energy budgets were constructed for a time of day-season matrix for canvasbacks using riverine and main bay habitats. Canvasbacks were very active at night, making regular and often lengthy crepuscular movements (x = 11.7 km) from near shore habitats during the day to off shore habitats at night. Movement patterns were similar for birds using habitats on the eastern and western shores of the Bay. Canvasbacks had extensive home ranges averaging 14,286 ha, and used an average of 1.97 core areas. Sleeping was the predominant diurnal behavior. Telemetry indicated that canvasbacks actively fed at night. Canvasbacks spent more time in active behaviors (e.g. swimming, alert) on the eastern shore than on the the western shore. Similarly, canvasbacks were more active during daytime hours at locations where artificial feeding occurred. Behavioral patterns were only weakly correlated with weather patterns. Canvasbacks appeared to reduce energy expenditure in mid-winter by reducing distances moved, reducing feeding activities and increasing the amount of time spent sleeping. This pattern was observed even though 1988-89 mid-winter weather conditions were very mild. / Master of Science

Ruppia maritima is a euryhaline hydrophyte found as a cosmopolitan inhabitant of shallow water habitats. In Chesapeake Bay, Ruppia maritima L. (Potamogetonaceae) and Zostera marina L. (Zosteraceae) form an important submerged aquatic vegetation community. Research in Chesapeake Bay has focused primarily on Zostera marina. Ruppia maritima occurs abundantly in large monospecific stands as well as in mixed stands with Zostera marina. Recent surveys have shown that natural revegetation in some areas has occurred and Ruppia maritima was the primary colonizer in the natural revegetation of some areas. The objective of this study was to investigate the reproductive biology of Ruppia maritima including the possible function of seed banks and vegetative and sexual propagules on the colonization of new habitats, and the plant's ecological impact around Goodwin Islands, York County, Virginia. Ruppia maritima rapidly colonized experimental plots that have historically been mixed beds or have been monospecific beds of Zostera marina because it utilized a combination of sexual and asexual reproduction. Ruppia maritima colonized plots by rapid rhizome growth. Seed reserves were probably more important in re-establishing populations than in "maintenance" of populations. Ruppia produces energy costly Post-reproductive shoots. These shoots which produce inflorescences (and then seeds) remain viable after seeds mature and can detach, disperse, and colonize sites. First year plants were not found to produce an inflorescence. This is significant in the establishment of new habitats. If a fledgling population is distressed by poor water quality or sediment disturbance, the possibility of producing seeds seems to be eliminated unless the plants have been established for one full growing season. This may explain the ephemeral nature of some Ruppia populations. / Ph. D.

年報中富含眾多資訊，其中包含財務性資訊與文字性資訊，財務性資訊之分析方法已相當成熟，而文字性資訊受限於格式及檔案類型，而降低投資人使用或分析此類資訊之效率。管理階層討論與分析(Management’s Discussion & Analysis of Financial Condition and Results of Operations，以下簡稱MD&A)係管理階層傳達其經營決策觀點予投資人之媒介，投資人可透過閱讀MD&A取得更多資訊，過去學者之研究亦證實該項目內之文字性資訊有其重要性，由於文字性資訊缺乏通用之分類架構，因此投資人需耗費較多時間與成本分析該資訊。本研究自美國科技業上市公司，隨機選取40家企業2012年之年報作為樣本資料，藉由文字探勘技術，運用TFIDF將MD&A文字性內容分類至EBRC針對MD&A所發布之分類架構，建立分類閱讀器，使投資人可利用透過系統分類並彙整之文句，迅速取得所需之文字性資訊，以協助使用者有效率地閱讀這些非結構化之文字資訊，藉以減少資料蒐集之時間，提升文字性資訊之可使用性。 / Annual reports are rich in information, which contains financial information and textual information. While the approach of analyzing financial information is common, textual information is confined by its format or the file type it is stored, thus decreasing the efficiency of analyzing this sort of information. Management’s Discussion & Analysis of Financial Condition and Results of Operations (MD&A) is the vehicle for investor to share the sight of managements’ decision making consideration, through reading MD&A investor could obtain more information. According to past researches, textual information is of importance. Due to the lack of a common framework, investors would consume more time and cost to analyze textual information. This research randomly selected 40 samples from publicly traded technology firms of the United-States. Utilizing text-mining technology and TFIDF, classify textual information of MD&A into the framework EBRC established, developing a classified reader for MD&A. To assist investors read non-constructed textual information efficiently and reduce the time of information gathering, thereby enhancing the usability of textual information.

本研究使用TFIDF文字探勘技術分析樣本公司年度財務報告裏的管理階層討論與分析(Management’s Discussion & Analysis of Financial Condition and Results of Operations，以下簡稱MD&A)與財務資訊，欲探討公司內部控制有效性對於MD&A資訊與財務資訊一致性之影響。本研究樣本自2002年至2014年美國上市櫃公司之年報中選取，研究結果顯示，當內部控制出現重大缺失，會對企業財務報導一致性產生顯著影響，內部控制具備有效性，其財務資訊與MD&A文字性資訊所揭露之訊息較為一致。 / The major purpose of this study is to examine the relationship between internal control weakness and the financial reporting consistency. I use TFIDF text mining technology analysis the Management's Discussion & Analysis of Financial Condition and Results of Operations (MD&A) and financial information. All annual report of the US-listed companies from 2002 to 2014 are collected as data samples. As anticipated, we find that internal control weakness is negatively correlated to the financial reporting consistency. Companies with no internal control weakness present more consistent MD&A information comparing to their financial information.