ESSAYS IN CROSS-COUNTRY CONSUMPTION RISK SHARING

This dissertation concerns cross-country consumption risk sharing in a long-run perspective. Financial integration, empirically measured by cross-country holdings of assets and liabilities, has increased dramatically in the past two decades. But what can explain the lack of cross-country risk sharing documented in the literature? Chapters 2 and 3 of this dissertation address this question. In Chapter 2, we set up a model to illustrate the mechanical difference between a bond economy and an insurance economy. We show that a bond economy can intertemporally smooth consumption in face of transitory output shocks, but not for permanent output shocks; an insurance economy is essential for risk sharing on permanent shocks. We therefore show that when both transitory and permanent output shocks exist, transitory shocks only create "noise" if the focus of interest is on identifying risk sharing in the long run. In Chapter 3, we specify an empirical nonstationary panel regression model to test long-run consumption risk sharing across a sample of OECD and emerging market countries. This is in contrast to tests in the literature which are mainly about risks at business cycle frequency. We argue that these existing tests neglected the permanent elements of risks that are of interest and that their model specifications were not rich enough to accommodate heterogeneous short-run dynamics. Since our methodology focuses on identifying cointegrating relationships while allowing for arbitrary short-run dynamics, we can obtain a consistent estimate of long-run risk sharing while disregarding any short-run nuisance factors. Our results show that, for the period of 1950-2008, the level of long-run risk sharing in OECD countries is similar to that in emerging market countries. However, during the financial integration episode of the past two decades, long-run risk sharing in OECD countries increased more than in emerging market countries. Furthermore, we investigate the relationship between various measures of financial integration and cross-country risk sharing, but only find weak evidence of such linkages

六十年代之死

終於都將六十年代之死寫完了，從暑期開始到現在，寫了九個多月，十改其稿，不斷的重寫，讓我發現寫作既辛苦，但是很有挑戰性，充滿無限可能的東西。 這個故事叫六十年代之死，與我初時構想的一樣，想藉著在六十年代死去的男主角洛仁，重生到九十年代的時候，如何發現他不可能活在新的年代，新的價值觀。最後，他也要再死一次，方能擺脫那種反差帶來的痛苦與無助。洛仁的重生與死亡，是希望能比較兩個年代的人，從而引人反思。到底以往香港的東西是否一定要受淘汰，我們是否應該了解到有些東西我們應保留呢？ 在構思這個故事的初期，我總是單從故事的發展著眼，反而很多時離開了自己想要表達的主題以及情感。甚至看了金庸，不斷學他的寫法。特別在情節安排以及人物心理描寫二者，尤其希望可以作為參考。可是金庸寫的是長篇小說，對於中篇小說的六十年代之死，似乎不可以作為參考。而且在人物描寫方面，亦不可能花太多篇幅，例如：寫人物的衣飾。所以最後我以洛仁為中心，集中講他的心情以及看法。幸好也斯將我不斷修正在正確的軌道上。我實在沒有寫小說的經驗，單憑信心與毅力，原來並不會寫得出好的小說。寫過小說，更深刻明白多看、多寫的道理。 在創作的過程之中，從敍事的手法、人物心理描寫和故事的結構，都有很深的體會。特別我以往那種假「意識流」寫法，想到甚麼就寫。說好聽是靈感不絶，說實話就是亂寫一氣，完全不能緊扣主題。這種過份自由的寫法破壞了主線，而且令全篇文章得不到應有的發揮。而且情節配合應該是故事發展的副主線，如果過份自由敍事，没有一定的方向，主題會受到情節支配，不能顯現主題。 緊扣主題的時候，必須將題材去蕪存菁，與主題無關的，盡量不要﹐以免影響作品的情節。中學讀到葉紹鈞的〈以畫為喻〉，這次完全印證了。 創作歷程之中，我發現每一個段落，甚至每個用字，都必須表現自己想說的主題。初時雖然盡量扣緊主題，但是都被情節佔據了大部份的篇幅。後來不斷修正，與也斯談及敍事角度等問題，才知道主題不一定從情節出，可以從心理獨白等不同方式表現。寫人物心理與敍寫情節很不同。描述心理的時候，以第一人稱比較容易表達，而且可以省去不少没有用的枝節。 對這篇的主人翁施洛仁，以第一人稱的表現方式處理，顯然更加集中。第一回是月芳的片段式回憶。我自己很喜歡那一回，没有參考過甚麼書，只是覺得片段回憶最能表達她的感情。後來再寫第二、三回的時候，初時以全知觀點去寫。發現枝節太多，在有限的篇幅，根本不能處理得好。因此，我大膽將往後的回數，全部以洛仁的第一人稱去寫。而且兩次運用了回憶的手法。首先，希望在故事結構上取得平衡；另外，就是透過洛仁陰、陽兩次的回憶，讓洛仁自己去選擇，他回憶之中最重要的部份。最近一回寫得很少，是因為對於婕平的死以及世界的改變，洛仁都不願提太多。而且他們如何死，亦無需交代。 這個故事顯然很少對白的存在。上年白先勇先生說到對話是最重要的部分，如果寫得不好，必定會破壞到全篇故事。而且對話寫得不好，没有可觀性。受到他的影響，我在寫對話總是戰戰悚悚，於是我用心聲代替說話。例如第二回洛仁死後 後知道每個人的心聲，從而引起他的內疚、後悔，都是我刻意安排。另外特別寫幾個鄰居的分別，例如：張先生的「唉…」，也是嘗試突出不同的性格。 再一次感謝也斯抽很多時間幫我改文。見到他忙個不停，就會知道他很想放假去玩，創作他的故事。很久以前，我就覺得這個世界越來越現實，人生存在世，越 來越没有意義。特別是新一代的青年，更不知快樂為何物。我想自己的創作可以告訴別人，情感還是有它的價值。而且，現在的香港社會問題越來越複雜，很想以文章記錄並反思這些現象。不知終此一生，可不可以做到這幾點？而這一又可 以表達幾多？還請各位多多指點

Review of advances on longitudinal vibration of submarine propulsion shafting and its vibration reduction technology

Analyzed the formation mechanism of longitudinal vibration of the submarine propulsion shafting system, and introduced its existing vibration control technology. The content included the improvement design of propulsion shafting system, new types of thrust bearing, composite material shaft, dynamic vibration absorber, phonon crystal band gap damping and relative active control technology. A new method for the application of metal rubber technology in thrust bearing was put forward, which provided a new idea for the research work in the future

Teacher Incentive Pay Programs in the United States: Union Influence and District Characteristics

This study examined the characteristics of teacher incentive pay programs in the United States. Using the 2007–08 SASS data set, it found an inverse relationship between union influence and districts’ incentive pay offerings. Large and ethnically diverse districts in urban areas that did not meet the requirements for Adequate Yearly Progress as defined under the No Child Left Behind Act are more likely to offer a larger number of economic incentives. Although rural districts are likely to reward teachers in hard-to-staff schools, they are not more likely to reward teachers who are certified by the National Board or who teach in the subject areas of shortage, nor are they more likely to offer multiple financial incentives

Operation Analysis on Refrigeration System Combined with Heat Pipe

In data center, telco equipment station and some central control rooms, there are some cases with cooling requirement all the year, their temperatures are usually controlled strictly whenever in summer or in winter. Moreover, due to clearness and safety requirement, the chiller should provide cooling water all the time even the outside environment is very cold. There had been some considerations about provide cooling capacity in cold climate with free environmental air by various heat exchangers directly. Without operating chillers, annual energy consumption on temperature control could be decreased. This paper proposed a system combined a chiller with an air-cooled heat exchanger, shown as Fig 1., there is one evaporator to provide cooled water, two condensers for the chiller and the separate type heat pipe alternatively. In warm climate, the chiller operates normally with the compressor and its condenser, the air cooling heat pipe is blocked by switching valves. In cold climate, the system is switched to the no compressor mode, the air-cooler heat exchanger could connect with the evaporator directly, the work pattern follows the separated type heat pipe, the working medium is the refrigerant still, the air cooling heat exchanger serves as the condenser of the separated type heat pipe, therefore, the evaporator is the evaporating part of the separated type heat pipe as well, the cooled water could be delivered through normal pipelines. In application of the combined refrigeration, they operation strategy for refrigeration and the heat pipe should be discussed in different climate zones. Therefore, in this paper we discussed energy consumption for cooling requirement in data center at several typical regions based on the combined cooling system. In different regions, their climates condition are different, the switching between the normal refrigeration and the heat pipe results to various annual energy consumptions

QE Auctions of Treasury Bonds

Divisions of Research & Statistics and Monetary Affairs -- Federal Reserve Board, Washington D.C

Treasury Inconvenience Yields during the COVID-19 Crisis

In sharp contrast to most previous crisis episodes, the Treasury market experienced severe stress and illiquidity during the COVID-19 crisis, raising concerns that the safe-haven status of US Treasuries may be eroding. We document large shifts in Treasury ownership and temporary accumulation of Treasury and reverse repo positions on dealer balance sheets during this period. We build a dynamic equilibrium asset pricing model in which dealers subject to regulatory balance sheet constraints intermediate demand/supply shocks from habitat agents and provide repo financing to levered investors. The model predicts that Treasury inconvenience yields, measured as the spread between Treasuries and overnight-index swap rates (OIS), as well as spreads between dealers’ reverse repo and repo rates, should be highly positive during the COVID-19 crisis, as is confirmed in the data. The same model framework, adapted to the institutional setting in 2007–2009, can also explain the negative Treasury-OIS spread observed during the Great Recession

Structural Color 3D Printing By Shrinking Photonic Crystals

The rings, spots and stripes found on some butterflies, Pachyrhynchus weevils, and many chameleons are notable examples of natural organisms employing photonic crystals to produce colorful patterns. Despite advances in nanotechnology, we still lack the ability to print arbitrary colors and shapes in all three dimensions at this microscopic length scale. Commercial nanoscale 3D printers based on two-photon polymerization are incapable of patterning photonic crystal structures with the requisite ~300 nm lattice constant to achieve photonic stopbands/ bandgaps in the visible spectrum and generate colors. Here, we introduce a means to produce 3D-printed photonic crystals with a 5x reduction in lattice constants (periodicity as small as 280 nm), achieving sub-100-nm features with a full range of colors. The reliability of this process enables us to engineer the bandstructures of woodpile photonic crystals that match experiments, showing that observed colors can be attributed to either slow light modes or stopbands. With these lattice structures as 3D color volumetric elements (voxels), we printed 3D microscopic scale objects, including the first multi-color microscopic model of the Eiffel Tower measuring only 39-microns tall with a color pixel size of 1.45 microns. The technology to print 3D structures in color at the microscopic scale promises the direct patterning and integration of spectrally selective devices, such as photonic crystal-based color filters, onto free-form optical elements and curved surfaces

Asynchronous Opinion Dynamics with Online and Offline Interactions in Bounded Confidence Model

Open Access journalNowadays, in the world, about half of the population can receive information and exchange their opinions with others in online environments (e.g. the Internet), while the other half obtain information and exchange their opinions in offline environments (e.g. face to face) (see eMarketer Report, 2016). The speed at which information is received and opinions are exchanged in online environments is much faster than in offline environments. To model this phenomenon, in this paper we consider online and offline as two subsystems in opinion dynamics, and there is asynchronization when the agents in these two subsystems update their opinions. We show that asynchronization strongly impacts the steady-state time of the opinion dynamics, the opinion clusters and the interactions between the online subsystem and offline subsystem. Furthermore, these effects are often enhanced the larger the size of the online subsystem