How can people's expectation capture business cycle and affect the relationship between housing market volatility and expected housing asset returns?

論文發表人: 黃美綺 (加州大學河濱分校經濟系博士班)

 

http://www.gbdi-conference.org/11.html

 

本論文為美國房屋市場1963至 2007的實證研究。其採用考慮由於心理預期造成的波動反饋效果的模型, 來檢視房屋市場波動和預期房屋資產報酬之正相關性。此外, 將Markov-switching特性融入房屋價格成長率波動, 來觀察此模型是否能反映美國景氣循環。爲與暫時性房價波動區分, 特結合其他相關房市變數, 來估測美國房市長久轉折時點。本研究發現, 依據三個不同轉折點區分之任何時期, 房屋市場波動和其預期資產報酬皆為正相關。此外, 本模型的房價成長高波動時期, 能夠充分反映除了1973-75之外的所有蕭條期。

 

This paper empirically investigates the housing market during 1963-2007 by incorporating volatility feedback effect to examine if relationship between housing market volatility and expected housing asset returns rate is positive under the framework of Campbell and Hentschel (1991) and extended version by Kim, Morley and Nelson (2004). This model is able to capture the power of economic agents' expectation based on some information availability assumptions by introducing Markov-switching housing market volatility. To determine the breakpoints with permanent structural changes, instead of choosing any convenient break date, I employ Perron and Qu (2006) framework by estimating some bivariate VARs for housing prices and some relevant housing variables. Based on the results from VARs, I choose three break dates--1984Q1, 1990Q1, and 1999Q1. All empirical results indicate that there is significantly negative volatility feedback effect. Importantly, except 1973-75 recession, this model captures all NBER-dated recessions including recession in 2001.

Bilingual Practices: Mexican American Immigrant Children's Code-Switching in Peer Play Interactions in a Bilingual U.S. Preschool

論文發表人：湯雅婷 (加州大學聖塔芭芭拉分校教育研究所博士班)

 

http://www.aera.net

 

會話分析學派的學者嘗試由對話情境中的對話細節去瞭解語碼轉換的現象。本研究採用民族誌研究法，長時間記錄美籍墨裔幼兒在雙語幼稚園中與同儕互動的情況。本研究並採用會話分析法，分析幼兒的互動以及雙語對話。研究結果發現美籍墨裔幼兒善於運用自身的雙語資源，並將語碼轉換做為一種應對技巧，進而影響遊戲中同儕群體互動的參與架構。研究的結果證明雙語教育將對雙語幼兒在社會化的發展上有所助益，並且對美國加州227教育法案提出合理性的質疑。

 

Recently, researchers working within the framework of conversation analysis have argued that in order to understand code-switching, the analyst must attend to "the details of its local production in the emerging conversational context which it both shapes and responds to" (Auer, 1998). This study analyzes examples of talk from an ethnographic study of children's free play peer interactions recorded at a bilingual preschool program serving Mexican-American families in California. The analysis demonstrates how children use code-switching to shift the local "participation frameworks" (Goodwin, 1990) of their play during moment-to-moment sequences of interaction. Results are discussed in terms of implications for educational policy.

Casimir force between inclusions in a stretchable fluid membrane

論文發表人: 林香谷 (加州大學河濱分校物理系)

 

http://meetings.aps.org/Meeting/MAR09/Event/94611

 

我們計算在可伸展細胞膜表面引入外來物顆粒後因熱微擾產生的熵力。這種熵力可看作是在有限溫度下的喀西米爾力。在我們的模型中考慮了細胞膜因為表面張力與彎曲所產生的能量改變。為了簡化計算，我們考慮兩個圓盤形狀的外來物，藉此，可以讓細胞膜原來的正常模態發生改變，進而造成喀西米爾效應。我們的結果包含了任意強度微擾造成的熵力，其中涵蓋外來物是孔洞，剛性圓盤等等。我們計算也考慮了邊界效應對系統的影響。

 

We calculate the entropic fluctuational force, a finite- temperature analogue of the Casimir force, between foreign inclusions in a strechable fluid membrane. Specifically, we consider the fluctuations of a planar membrane governed by the full Helfrich Hamiltonian, including the surface tension and both bending rigidity terms. The inclusions are introduced as circular regions where the surface tension and/or bending rigidities are modified from their values on the non-perturbed membrane.  Results for arbitrarily-strong perturbations of the membrane, including holes, rigid disks, and edges will be presented.

 

Structural Health Monitoring for Frame Models with Damaged Joints

論文發表人:林俊宏  (加州大學聖塔芭芭拉校區機械工程博士班)

 

http://spie.org/smart-structures-nde.xml

 

本論文提出一個利用量測結構之動態反應，可用於桁架結構，包括樑、柱、接頭等部位之結構檢測法。此研究包含了一個將複雜的桁架模型簡化的技巧，並以此技巧增強了一個之前提出的結構動態檢測法。我們利用在地震發生時，在每一層樓量測到的結構動態反應，例如加速度、速度、位移等資訊，配合一個將結構中不同區域狀態分離的演算法，使得結構中的損壞可以被偵測以及定位出來。在此論文中，我們利用兩個數值模擬的模型來驗證這個結構檢測法，第一個例子是一個三層樓的桁架結構，另一個例子則是一個類似結構檢測基準模型的四層樓、雙間隔的桁架結構，這兩個例子都成功地驗證了我們提出的結構動態檢測法。

 

This paper presents a method of detecting and locating structural damages in beams, columns or joints of a frame structure by directly using structural vibration measurements. A previously developed damage diagnosis technique is enhanced by including an equivalently simplified lumped-mass model of the complex frame structure. The parameters derived from the simplified lumped-mass model are used in the damage diagnosis algorithm, while the actual dynamic responses measured from the frame structure under seismic excitation are used as the inputs. The dynamic responses measured from different floors can be decoupled by using the proposed damage diagnosis algorithm. As a result, damages in the frame structure can be detected and located. Numerical examples of a three-story-one-bay steel frame model and a benchmark-liked four-story-two-bay steel frame model are considered to demonstrate and evaluate the usefulness and effectiveness of the present method.

 

 

Monolithic 1.58-micron InAs/InP quantum dash passively mode-locked lasers

論文發表人：林昌億（新墨西哥大學光電所博士班）

 

http://spie.org/x19316.xml

 

在這篇論文中，我們報告了在磷化銦基版上生長的砷化銦量子段單積體1.58微米波段被動鎖模雷射元件。此雷射元件的重複頻率可達到18.5千兆赫。Dashes-in-a-well作用區域結構包括了五層受壓應變的AlGaInAs量子井包覆的砷化銦量子段，外圍有30奈米受張力應變的AlGaInAs層。雷射元件共振腔長度為二至三公釐，有著4微米寬的脊形波導管，其波導每隔0.5公釐劃分著電絕緣的正極接觸區塊。我們經由改良的分節觸點測量法得到砷化銦作用區域的模式增益及耗損譜，並確認砷化銦量子段的光電特性是半導體鎖模雷射所需求的。分節的波導管在同樣的DWELL作用區域下被重新焊接成分隔的增益及吸收區塊。我們在在吸收區塊旁的刻面鍍上一高反射膜(95%)，而另一刻面則是自然斷面。為了解共振腔設計及決定增益與吸收段長度的比例關係，我們以微波光子學的角度推導出一個針對兩段式被動鎖模雷射器件的共振腔設計模型。新推導出的理論方程式可經由量測的模式增益與損耗特性數據找出最佳雷射元件腔長設計。

 

Monolithic InAs quantum dash 1.58-micron passively mode-locked lasers grown on an InP substrate are reported. A repetition rate of up to 18.5 GHz has been realized. The dashes-in-a-well (DWELL) active region consists of 5 stacks of InAs quantum dashes embedded in compressively strained Al_0.20Ga_0.16In_0.64As quantum wells separated by 30-nm undoped tensile-strained Al_0.28Ga0_.22In_0.50As spacers on both sides of the DWELL. 4 micron-wide ridge waveguides with cavity lengths in the range 2-3 mm were fabricated with equal-length, electrically-isolated anode contacts, each 0.5 mm in length. The modal gain and loss spectra of the InAs active region were then measured through the improved segmented contact method, and the characteristics that make InAs quantum dash materials system desirable for semiconductor mode-locked lasers were identified. The segmented waveguides were then reconfigured into mode-locked lasers by wire bonding the segments together to form separate gain and absorber regions that use the same DWELL active region. A highly reflective coating (95%) was applied to the mirror facet next to the absorber while the other facet was cleaved. To assist in the cavity design and determine the relative length of the absorber and gain sections, a model for the cavity geometry of two-section passively mode-locked lasers was studied that is based on a microwave photonics perspective. The new set of theoretical equations was used to find the optimal device layout using the measured modal gain and loss characteristics as input data.  

Effects on Hardness and Elastic Modulus for DSS-8 Peptide Treatment on Remineralization of Human Dental Tissues

論文發表人 : 許家展 (加州大學洛杉磯分校材料科學與工程學系)

 

http://www.mrs.org/s_mrs/sec.asp?CID=6688&DID=174641

 

縮氨酸及含有氨基酸的聚合分子特別是含有大量羧酸鹽是被認為可與礦物表面交互反應。這些縮氨酸大部分反應於調解生物礦化成長。在這份研究中，探討DSS-8縮氨酸對再礦化之人類牙齒組織影響。 結果表示，經過含有DSS-8縮氨酸之再礦化處理的去礦化的琺瑯質及未處理的象牙質其硬度增加。另外，有添加DSS-8縮氨酸處理的去礦化的琺瑯質及未處理的象牙質其硬度與彈性模數高於未添加DSS-8縮氨酸處理。

 

Peptides and macromolecules contain amino acid residues, specifically regions rich in carboxylates, as known to interact with mineral surfaces. Those peptides are most active in the mediation of biologically directed mineral growth. In this work, the effects of DSS-8 peptide treatment on remineralization of human dental tissues are investigated. The results show that hardness of demineralization enamel and native dentin increases after remineralization treatment with DSS-8 peptide.  Additionally, hardness and modulus of demineralization enamel and native dentine with DSS-8 peptide treatment are higher than that without DSS-8 peptide treatment.

 

 

Multi-scale analysis of InSAR time series to estimate variations in topographically correlated propagation delays with application to the Makran Subduction Zone

論文發表人: 林玉儂(加州理工學院)

 

Many InSAR observations are plagued by propagation delays that correlate with topographic variations within a given scene.  These delays are frequently termed tropostatic delays and are assumed to result from temporal variations in horizontal stratification of the troposphere.  We present a robust approach to estimating tropostatic compensation coefficients (K values) that is relatively insensitive to confounding processes (e.g., earthquake deformation, phase ramps from orbit errors, etc). Our approach takes advantage of a multiscale perspective by adopting wavelet decomposition of both topography and observed phase.  By decomposing topography and observed phase in a given interferogram into several spatial scales, we determine the bands spanning different characteristic length scales wherein correlation between topography and phase is significant and stable.  Our approach also uses the inherent redundancy provided by multiple interferograms constructed with common scenes. We define a unique set of component time intervals, Tint, using a suit of interferometric pairs. The pair-based K values (Kpair) are then combined to estimate temporally consistent values for each time interval (Kint).   The Kint values are then recombined to make final values of Kscene in order to correct each interferogram. 

We are testing our approach in the region of the Makran subduction zone, located in western Pakistan and eastern Iran, within the influence zone of South Asian monsoon. We use twenty-nine ENVISAT images to develop the time series. Preliminary results find large variations in estimates of Kscene and Kint.  Generally, the tropostatic correction accounts for a relatively small portion for the phase observed, although significant effects are found for selected pairs.  The typically small impact of the tropostatic correction implies that in the future we must consider more complex dynamic atmospheric models.

 

差分合成孔徑雷達影像是用來做同震地表變形判釋的重要工具，然而用在震間低幅度的地表變形上，卻有很大的限制，因為低幅與低頻的震間變形行為所產生的訊號容易受到傳輸延遲的干擾，這種延遲與地形起伏呈共變現象，又被稱作對流層延遲，起因於對流層在垂直向分層的時間變化。本研究使用地形與相位間的線性相關模型，建立一個方法以估算其轉移函數K，此方法對於其他地質現象（構造變形、軌道誤差造成的大尺度相位傾斜）相對不敏感，因而能提供較可靠的K值。此多尺度分析法利用小波轉換將地形與差分雷達影像分成數個不同的空間尺度，其中某些特定尺度顯示出較高的地形相位共變關係，而且其所得到的K值比起其他尺度相對穩定，表示不受到其他因素的干擾。本研究同時利用多幅影像所提供的內在冗餘性來建立非重覆性的時間序列，首先我們定義一組非重覆的時間段落Tint，與其對應的轉移函數Kint，則以各差分合成孔徑雷達影像為基礎的轉移函數Kpair便是Kint的線性組合。解此線性系統便可得到Kint的時間序列，並可由其推測所以其他差分合成孔徑雷達影像的Kpair。

我們將此一方法應用在巴基斯坦與伊朗邊界的莫克蘭隱沒帶，該地區曾於1945年發生規模8的強震，並在周圍印度洋海岸造成海嘯災害。我們希望透過傳輸延遲校正可以得到較為精確的震間變形量，進而了解目前在隱沒帶上的應力狀態。測試的結果發現，我們的方法可以在山區得到不錯的校正量，但是校正後影像仍舊呈現出不小的對流層訊號，推測應該與動態的對流層變化諸如局部對流或是背風波有關。這表示我們下一步需要考慮動態對流層變化的校正。

Offset ancient city wall yields plausible slip rate for the Sagaing fault, Burma (Myanmar)

 

論文發表人：王昱（加州理工學院 地質與行星科學系 博士班）

http://www.agu.org/meetings/fm08/

 

The Sagaing fault offers great potential for paleoseismology study, because it traverses a region with a long history and high rates of sedimentation.  Buddhist documents from ancient Pegu (Bago), in southern Myanmar, record 34 strong earthquakes in the past 2.3 millennia. The latest of these is the 1930 Pegu earthquake (M 7.3), which had high intensities along a 90 km stretch from Pegu to the southern coastline of the country. 

We have found evidences for surface rupture in 1930 in the stories of village elders and in offset paddy fields.  These reports and offsets suggest that coseismic displacement decreased from several meters in Pegu to liquefaction without faulting near Payagyi Township, 15 km farther north. West of Payagyi, the fault trace cuts through and offsets an ancient city wall. The age of the ancient city is uncertain, but descriptions from Burmese history indicate it was built in the late 16^th century, probably about 440 yrs ago.

Determination of the offset of the 440-year-old city wall is possible, but not simple, in part because vertical displacements across the fault have resulted in differential sedimentation on the flanks of the wall.  After accounting geomorphologically for the differential sedimentation, the offset of both the outer and inner edges of the city wall appear to have sustained a right-lateral offset of about 6 meters.

This yields an approximate slip rate of 14 mm/yr, which is slightly lower than the slip rate determined by others from GPS geodesy. The number of earthquakes involved in creating the 6-meter offset is currently unknown, but paleoseismic excavations within the ancient city may well yield evidence of discrete offsets that we will be able to ascribe to specific large earthquakes in the historical record.  Candidates include historical earthquakes 1582, 1644, 1768, 1830, 1888, 1913 and 1917 C.E.

 

實皆斷層(Sagaing fault)為南北向貫穿緬甸全境的主要走滑斷層。由於該斷層通過具有長期歷史紀錄及高沉積速率的地區，為一具高潛力的古地震研究區域。

於過去的二千多年中，位於勃古(Bago)的佛教典籍紀錄了南緬甸地區多達34次的強烈地震，最後一次規模7.3的強震發生於1930年，並造成該地區的嚴重死傷。然而，該事件僅留下部分片段的地表破裂紀錄，對於古地震事件的研究並無太多的助益。

本研究透過現地調查及口述歷史的方法，揭露了1930年地震的同震變形可能情境。調查顯示實皆斷層(Sagaing fault)1930年的地表破裂在通過勃古城後即向北遞減，由數公尺遞減至難以辨認的程度。 距離勃古城以北15公里處，調查亦發現該斷層穿過一古城遺跡，並錯移該遺跡之北面城牆。雖然至目前為止，對於該遺跡之年代並無科學上的定論，但透過緬甸歷史之描述，我們相信該遺跡應建於16世紀末期，據今約有440年之譜。透過電腦模擬方式，本研究建議該古城牆所紀錄的錯移量約在6-8公尺之譜。

此結果顯示實皆斷層(Sagaing fault)的大約滑移速率約在每年1.4 -1.8 公分之間，與近年的GPS觀測結果相近。目前我們並不清楚這6-8公尺的位移與哪些歷史地震有關，但應不脫公元1582，1644，1768，1830，1888，1913 及1917 的地震事件。對於該遺跡的更進一步調查或可揭露實皆斷層(Sagaing fault)於過去數百年間的詳細活動行為，並將對東南亞該地區的潛在地震災害有更進一步的認識。

 

Minimally Invasive Parylene Dual-Valved Flow Drainage Shunt for Glaucoma Implant

論文發表人：林峻暉（加州理工學院電機系博士班）

 

http://www.mems2009.org/

 

本篇論文發表了一個由聚對二甲基苯材料所製作，應用於治療青光眼的雙節流閥控制流體之植入式元件。藉由整合的雙節流閥結構，此元件能夠以物理性的方式來排出過多的眼內液體以此來調節眼壓至適當的15-20豪米汞柱。除了基本的功能性微流體元件外，加上為手術而特別增加的設計，例如一個聚對二甲基苯容納管與固定器，也同時整合在此一元件當中，因此可以成功達成最小侵入式，術後無須縫合的手術目標。聚對二甲基苯固定器擁有一個非常深的半圓形溝槽，這是運用乾式薄膜光阻的技術製作而成。由於固定器的存在，可以防止元件在植入眼睛後發生滑動的現象。實驗室的實驗已經成功驗證了此一元件的確可以提供帶通式的流體控制結果，此結果完全可以滿足青光眼醫療上的需求。實驗結果也顯示，後製製程與封裝程序可以將節流閥完整封裝於聚對二甲基苯容納管內而在測試時並無液體滲漏的現象發生。所以此一元件已經適合用於活體實驗的階段。藉由最佳化後的微機電製程與後製製程，此一元件乃是第一個應用於醫療系統當中，可應用於治療青光眼，被動的，零電力消耗，也無須加入任何電路設計的雙節流閥式控制流體植入式元件。

 

A parylene-enabled microvalved shunt implant for glaucoma drainage is presented in this paper.  Enabled by the dual-checkvalve operation, this device can physically drain the extra intraocular fluid and regulate the intraocular pressure (IOP) within the normal range (15-20 mmHg).  Improved surgical features, in addition to the functional/microfluidic components, such as parylene-tube carrier and anchors, are also incorporated in such device to realize minimally invasive suture-less implantation, suitable for practical in vivo use. The parylene anchor with very deep semi sphere recess is fabricated utilizing the dry film photolithography technique.  With this improved surgical features and the newly developed packaging techniques, the overall finished GDD form factor not only still keeps minimally invasive implantation possible, but also prevents dislodging after subconjuctival implantation.  A pressure-bandpass configuration is characterized by on bench verification which illustrates that the results meet medical requirements to treat glaucoma patients.  It also shows that the epoxy and photoresist sealing during the packaging and testing procedures secure the system from water leakage extremely well.  With the optimized micromachining and post-fabrication process procedures, the developed implant is the first checkvalved glaucoma drainage device (GDD), which is passive, consumes no additional power, and functions without any circuit involved to pursue its medical application.

Lower Frequency Metamaterial-Inspired Magnetic-Based EZ Antennas

論文發表人：林佳慶 (亞利桑那大學電機與電腦工程研究所博士班)

 

http://www.nrsmboulder.org/

 

Many applications have been proposed that use metamaterials (MTMs), artificial materials having engineered electromagnetic properties, to obtain a desired, but unusual electromagnetic behavior.  For instance, metamaterial-inspired efficient electrically small antennas have been proposed which have led to an efficacious, electrically-small antenna design methodology and have drawn much attention.  Inspired by the properties of MTMs and the ideas associated with this kind of antenna, we have extended the 3D magnetic-based EZ designs which operate at the lower frequency bands.  Several 300MHz 3D antenna were fabricated by filling in the dielectric gap with a quartz dielectric spacer. Not only did the quartz spacer provide the desired lower capacitance, it also enhanced the mechanically stability of the fabricated structure.  A series of realizations and designs of the 3D antenna and the corresponding measured results was shown that good agreement between the simulation and experimental results was obtained.

 

現今已有許多應用超常介質材料(matamaterial)來達成一個特別的電磁場行為，例如應用超常介質材料來設計一個有效率且極小天線的概念提供了本篇論文發展的基本設計方式，基於超常介質材料的特性及相關的天線設計方法，我們提出一個工作於300 MHz之3D EZ天線設計方式，為了達到小天線的要求，我們加入石英來提供足夠的電容值以達到天線共振要求，除此之外，石英也幫助了我們在實做天線時增加結構的穏定度，模擬和量測結果證明此天線系統之有效輻射效率大於90%且工作於所設計的頻率。

Sub-monthly Variability in the South American Monsoon System

論文發表人: 馬席研(加州大學洛杉磯分校大氣及海洋科學系博士班)

 

http://www.bom.gov.au/events/9icshmo/

 

本研究利用觀測資料與全球大氣與地表耦合模式的模擬結果，在月內 (sub-monthly) 的時間尺度下，探討亞馬遜雨林中心低層持續的西風與東風期間，南美季風系統的變異度。

觀測與模擬的降雨異常合成圖在巴西西北部和中部與東南部都呈現一個雙極類型。在盛行西風（東風）期間，巴西中部與東南部顯示降雨的正異常(負異常)，這同時也顯示南大西洋輻合區降雨的增強。此外，在盛行西風期間，季風區高層高壓也同時增強，並且位於南美上空的亞熱帶噴射氣流也同樣增強並且更接近赤道地區。

在亞馬遜地區東、西風盛行期間之前，南太平洋850毫巴重力位高度場的時間序列合成圖與該地區主要的低頻變異度(又稱為太平洋南美類型Pacific-South American patterns)非常類似。因此我們認為這個發現顯示了南太平洋溫帶大氣環流的低頻變異度與南美亞馬遜季風風場與降雨變異度的關連性。

 

We examine the sub-monthly variability of the South American Monsoon System (SAMS) with emphasis on three-day periods or longer during which the anomalous wind at low-levels in central Amazonia is consistently from the west or the east (westerly and easterly wind regimes, WWRs and EWRs, respectively). Our research methodology is based on observational, Reanalysis, and model data.  The latter is provided by simulations of an atmospheric general circulation model coupled to an advanced land surface model (AGCM/LSM).

For both wind regimes, the composites of observed and simulated anomalous precipitation show a dipole pattern with poles in northwestern and central-southeastern Brazil. During WWRs (EWRs), precipitation anomalies at the central-southeastern pole are positive (negative), indicating a stronger (weaker) South Atlantic Convergence Zone (SACZ). Furthermore, during WWRs the upper-level monsoon high is stronger and the subtropical jet in the South American sector is stronger and closer to the equator.

Lag composites of geopotential height anomalies at 850mb prior to the establishment of the wind regimes in Amazonia show the development of structures in the South Pacific that resemble the principal modes of variability in that region, which are usually referred to as the Pacific South American (PSA) patterns. This finding suggests that links exist between the wind regimes and the modes of intraseasonal variability over the South Pacific and over South America. Thus, it is proposed that the wind regimes over Amazonia are associated with low-frequency variability in the extratropical circulation.