Axicons are optical elements that produce Bessel beams,i.e., long and narrow focal lines along the optical axis. Thenarrow focus makes them useful ine.g. alignment, harmonicgeneration, and atom trapping, and they are also used toincrease the longitudinal range of applications such astriangulation, light sectioning, and optical coherencetomography. In this thesis, axicons are designed andcharacterized for different kinds of illumination, using thestationary-phase and the communication-modes methods. The inverse problem of axicon design for partially coherentlight is addressed. A design relation, applicable toSchell-model sources, is derived from the Fresnel diffractionintegral, simplified by the method of stationary phase. Thisapproach both clarifies the old design method for coherentlight, which was derived using energy conservation in raybundles, and extends it to the domain of partial coherence. Thedesign rule applies to light from such multimode emitters aslight-emitting diodes, excimer lasers and some laser diodes,which can be represented as Gaussian Schell-model sources. Characterization of axicons in coherent, obliqueillumination is performed using the method of stationary phase.It is shown that in inclined illumination the focal shapechanges from the narrow Bessel distribution to a broadasteroid-shaped focus. It is proven that an axicon ofelliptical shape will compensate for this deformation. Theseresults, which are all confirmed both numerically andexperimentally, open possibilities for using axicons inscanning optical systems to increase resolution and depthrange. Axicons are normally manufactured as refractive cones or ascircular diffractive gratings. They can also be constructedfrom ordinary spherical surfaces, using the sphericalaberration to create the long focal line. In this dissertation,a simple lens axicon consisting of a cemented doublet isdesigned, manufactured, and tested. The advantage of the lensaxicon is that it is easily manufactured. The longitudinal resolution of the axicon varies. The methodof communication modes, earlier used for analysis ofinformation content for e.g. line or square apertures, isapplied to the axicon geometry and yields an expression for thelongitudinal resolution. The method, which is based on abi-orthogonal expansion of the Green function in the Fresneldiffraction integral, also gives the number of degrees offreedom, or the number of information channels available, forthe axicon geometry. Keywords:axicons, diffractive optics, coherence,asymptotic methods, communication modes, information content,inverse problems

<p>Axicons are optical elements that produce Bessel beams,i.e., long and narrow focal lines along the optical axis. Thenarrow focus makes them useful ine.g. alignment, harmonicgeneration, and atom trapping, and they are also used toincrease the longitudinal range of applications such astriangulation, light sectioning, and optical coherencetomography. In this thesis, axicons are designed andcharacterized for different kinds of illumination, using thestationary-phase and the communication-modes methods.</p><p>The inverse problem of axicon design for partially coherentlight is addressed. A design relation, applicable toSchell-model sources, is derived from the Fresnel diffractionintegral, simplified by the method of stationary phase. Thisapproach both clarifies the old design method for coherentlight, which was derived using energy conservation in raybundles, and extends it to the domain of partial coherence. Thedesign rule applies to light from such multimode emitters aslight-emitting diodes, excimer lasers and some laser diodes,which can be represented as Gaussian Schell-model sources.</p><p>Characterization of axicons in coherent, obliqueillumination is performed using the method of stationary phase.It is shown that in inclined illumination the focal shapechanges from the narrow Bessel distribution to a broadasteroid-shaped focus. It is proven that an axicon ofelliptical shape will compensate for this deformation. Theseresults, which are all confirmed both numerically andexperimentally, open possibilities for using axicons inscanning optical systems to increase resolution and depthrange.</p><p>Axicons are normally manufactured as refractive cones or ascircular diffractive gratings. They can also be constructedfrom ordinary spherical surfaces, using the sphericalaberration to create the long focal line. In this dissertation,a simple lens axicon consisting of a cemented doublet isdesigned, manufactured, and tested. The advantage of the lensaxicon is that it is easily manufactured.</p><p>The longitudinal resolution of the axicon varies. The methodof communication modes, earlier used for analysis ofinformation content for e.g. line or square apertures, isapplied to the axicon geometry and yields an expression for thelongitudinal resolution. The method, which is based on abi-orthogonal expansion of the Green function in the Fresneldiffraction integral, also gives the number of degrees offreedom, or the number of information channels available, forthe axicon geometry.</p><p><b>Keywords:</b>axicons, diffractive optics, coherence,asymptotic methods, communication modes, information content,inverse problems</p>

Si l’information en continu semble constituer un genre télévisuel aujourd’hui installé, le modèle d’information qu’elle propose fait l’objet de nombreuses questions concernant les effets de reprise de l’information et la nature même de celle-ci. Parce que la chaîne BFMTV cristallise ces questions critiques, il a semblé pertinent, au moment où elle a plus de dix ans d’existence, d’essayer de comprendre le type d’information dont il s’agit. D’autant qu’elle se présente dorénavant, dans un contexte de convergence médiatique, sur plusieurs supports évoluant au gré des pratiques et des possibilités techniques, qui poussent à se pencher sur le lien que la chaîne, via son dispositif, entretient avec ses usagers. Pensé selon une approche pragmatique, ce travail a ainsi pour ambition de mieux cerner les enjeux de l’information en continu mais aussi ses impacts sur l’information en général. / If 24-hour news channels today seem to constitute an established television genre, the type of information that they provide leaves many questions open concerning both the re-presentation of information and the latter’s very nature. Because the 24-hour news channel BFMTV incarnates those critical questions, it seems relevant, more than ten years after its creation, to examine the model of information that it provides. Moreover, in the context of media convergence, this channel is now transmitted on several platforms that evolve according to the user's practices and existing technical possibilities. This fact leads to a further examination of how the channel develops a relationship, through its technical possibilities, with its users. Deploying a pragmatic approach, this thesis aims to achieve a better understanding of what is at stake in continuous news cycles and also of the impact that the latter have on information in general.

Background: The credit rating agencies have been heavily contested and criticized. In addition to this, other informational sources may potentially deliver the information that the CRA is intended to provide. This may have changed their role in reducing information asymmetry in the financial market. Purpose: This thesis will investigate (i) whether changes (upgrade/downgrade) in credit ratings lead to abnormal returns in share value, and thereby provide useful information to potential and current investors. The thesis will also (ii) examine whether there are significant differences between the periods before and after the GFC in 2008. Method: Regression based event study using a dummy-variable approach. Conclusions: No strong evidence that credit ratings have a significant effect on stock prices in the European stock market. Small indications that the market is responding more strongly to a rating change announcement during the period 2000-2008 compared to 2009-2019.

In this reviewwe discuss methodology to ascertain the amount of information in given data sets with respect to determination of model parameters with desired levels of uncertainty.We do this in the context of least squares (ordinary,weighted, iterative reweightedweighted or "generalized", etc.) based inverse problem formulations. The ideas are illustrated with several examples of interest in the biological and environmental sciences.

In this note we explain the use of the Akiake Information Criterion and its related model comparison indices (usually derived for maximum likelihood estimator inverse problem formulations) in the context of least squares (ordinary, weighted, iterative weighted or “generalized”, etc.) based inverse problem formulations. The ideas are illustrated with several examples of interest in biology.

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本研究的主旨在探討現金盈餘與會計盈餘之相對資訊內涵，並進一步探討會計選擇在股價形成中，所扮演之角色。FASB在觀念性公報第一號提出：應計基礎係將現金基礎彙總轉換，故其所包含的資訊較現金基礎來得多，品質也較高。因此，會計盈餘應較現金盈餘更具資訊內涵。而繼美國財務會計準則公報第95號公布二年後，國內於民國78年12月發布財務會計準財公報第17號「現金流量表」，故本研究探討會計盈餘與現金盈餘究竟何者較能解釋股票報酬？進一步分析淨應計項目是否具增額資訊內涵？最後將盈餘做理論上之分解，比較其資訊內涵，並利用公司規模、產業、應計項目幅度及營業週期等因素對該關係之解釋力做敏感度分析。 　　本研究以159家樣本公司作為研究對象，蒐集民國79年至84年的資料，以pooling 及橫斷面設計，迴歸分析來比較會計盈餘與現金盈餘和股票報酬的關聯性。 　　經由實證結果，本研究獲致如下的結論： 　　一、會計盈餘與現金盈餘資訊內涵之比較 　　會計盈餘與股票報酬關聯性大於現金盈餘與股票報酬的關聯。且稅後淨利的資訊品質優於營業淨利。 　　二、應計項目資訊內涵 　　　（一）除第一季及第三季外，淨應計項目並未具有超過盈餘之增額資訊內涵。 　　　（二）除第一季外，流動應計項目並未較非流動應計項目具有較佳的資訊內涵。 　　　（三）在反迴歸模式中，淨應計項目、流動及非流動應計項目均具有增額資訊內涵。 　　三、盈餘組成分子增額資訊內涵 　　　（一）將盈餘分解成營運之現金流量及淨應計項目，對股票報酬的解釋力並無增加；但淨應計項目有超過營運之現金流量之資訊內涵。 　　　（二）現金流量表中要素具有增額資訊內涵，其中營業及投資活動之現金流量皆具有資訊內涵，而理財活動則無。 　　四、敏感度分析：公司規模、應計項目幅度及淨營業項目的長短皆會影響盈餘、現金流量與股票報酬關聯性。 　　　（一）公司規模與股價報酬對會計資訊的反應有關聯，加入公司規模變數後，使盈餘與股票報酬關聯性增加。 　　　（二）應計項目的幅度會影響盈餘、現金流量與股票報酬關聯性。且應計項目幅度較小者，其結果較佳。 　　　（三）淨營業循環的長短也會影響盈餘、現金流量與股票報酬關聯性。且淨營業循環較短者，其結果較佳。

This dissertation studies the reaction of trading behavior of investors, especially institutional investors, to the public information in Taiwan. Two kinds of public information are chosen in this dissertation. One is open-ending closed-end funds under the regulation set up by Taiwan authority. The other is the change of stocks in MSCI Taiwan Index that is decided by Morgan Stanley Capital International (MSCI), a well-known foreign institution in constructing various indices. Consistent with earlier studies using U.S. data, our results show that open-ending is a wealth-enhancing event for shareholders. We also provide evidence of the existence of noise traders in the closed-end fund market. The evidence is derived from the trading behavior of domestic institutional investors and small individual investors, who ignore price discounts when open-ending is imminent. The trading by noise traders impedes price adjustments to the discounts, and provides profit opportunities to arbitragers. Furthermore, we show that foreign investors gain considerable wealth, largely at the expense of domestic institutional investors and small individual investors, in the open-ending process. On average, their gains account for 30% of the total gains associated with open-ending, or NT$562 millions per case. On the issue of the change of stocks in MSCI Taiwan Index, we find that MSCI prefers to select the securities with good performance, high liquidity, and large firm size into MSCI Taiwan Index while tends to drop the securities with poor performance, lower liquidity, and small firm size from MSCI Taiwan Index. Besides, consistent with the previous studies, prices increase (decrease) significantly for stocks added to (deleted from) the MSCI Taiwan Index after the announcement date. As well as the deletions, the price decreases for unchanging stocks after the announcement date. However, there is no evidence to find that foreign investors have information advantage in MSCI news over domestic investors. Foreign investors increase (decrease) their holdings on stocks included in (excluded from) the MSCI Taiwan Index after the announcement date. Moreover, price pressure hypothesis is not supported. Visibility hypothesis, information content hypothesis, downward sloping demand curves hypothesis are supported. Finally, for additions and deletions, the market-adjusted returns are driven by the contemporaneous excess buy of foreign investors and the contemporaneous excess sells of domestic corporations and individuals.

本研究觀察臺灣新上市公司的盈餘管理行為是否傾向於下半年或第四 季。且不同季別盈餘管理的舉措是否與股價操縱有關？如果答案為肯定， 則我國股市的資源與財富分配效效果，需進一步探討，並提出改良的方法 。 為驗證上述兩者之關聯性，本研究以民國 80 年至民國 83 年所有上市公司之年度財 務資訊與季資訊為樣本，用市場模式衡量 異常報酬，並比較年度間各類之淨應計項目，以 探討盈餘有用性、盈餘 管理之季節效應，及其與資訊內涵的關係。其實證結果顯示： (一)年度盈餘及季盈餘具資訊內涵，且季盈餘資訊內涵間具差異性。 (二)公司管理當局之年度間盈餘管理行為並未如預期地傾向於第四季或 下半年。 (三)公司管理當局年度間盈餘管理在好壞消息的樣本間是具差異性的，且在好消息 樣本間較顯著。 (四)公司管理當 局會利用季盈餘管理之結果來操縱股價。 綜合上述實證結果，由於盈餘資訊內涵的存在，對一般投資者而言，盈餘是有用的資訊，而公司當理當局會在年度中各季間從事盈餘管理行為來達成其預定目標。與本研究的 預期不同，公司管理當局不會在第四季或下半年特別作盈餘管理。由於我國股市投機風氣較盛，管理當局可能利用財務預測資訊或其他資訊來操縱股價，遠比盈餘管理有效。然原因如何尚待進一步探討。