Nonlinear waves, computer algebra and vortex dynamics

Session JE: Vortex Dynamics 5, abstract no. JE.001published_or_final_versio

Periodic solutions for systems of coupled nonlinear Schrödinger equations with three and four components

Periodic solutions of systems of coupled nonlinear Schrödinger equations (CNLS) was discussed. Hirota bilinear method and elliptic functions were used. It was found that each component of the CNLS may have multiple peaks within one period.published_or_final_versio

Periodic solutions for systems of coupled nonlinear Schrödinger equations with five and six components

Systems of coupled nonlinear Schrödinger (CNLS) equations arise in several branches of physics, e.g., optics and plasma physics. Systems with two or three components have been studied intensively. Recently periodic solutions for CNLS systems with four components are derived. The present work extends the search of periodic solutions for CNLS systems to those with five and six components. The Hirota bilinear method, theta and elliptic functions are employed in the process. The long wave limit is studied, and known results of solitary waves are recovered. The validity of these periodic solutions is verified independently by direct differentiation with computer algebra software. ©2002 The American Physical Society.published_or_final_versio

‘Unclear’ initial delineation of property boundaries and the third Coase Theorem

This interdisciplinary study, which references previous research on the evolution of land law and real world examples of land market operating with unclear property boundaries, demonstrates that Ronald Coase’s argument that delimitation of property rights is a prelude to market transaction applies to urban development, in which certitude in initial property boundaries in geodetic terms is not overriding. It explains why even a powerful landlord can be unsure of and do not even want to know the boundaries of the land of his/her tenants and why this mapping limitation in itself does not inhibit market transactions. When land is treated as an input for a chattel that is no longer fixed to land, area measurement is more important than boundary-fixing. When land becomes valued for its location and fixtures (i.e., as real estate), precise boundary delineations and disputes over the precision of cadastral surveys emerge. Boundary disputes are a particularly painful form of litigation. Feelings run high and disproportionate amounts of money are spent. Claims to small and valueless pieces of land are pressed with the zeal of Fortinbras’ army (Lord Hoffman in Wibberley v. Insley [1999] HL15).preprin

Surrendering the environment for capital gain and Olson's group theory: A case study of the dissolution of housing co-operative societies in Hong Kong

This paper describes the rise of the co-operative housing of civil servants and its fall during the transition of Hong Kong from a British colony to a special administrative region of the People's Republic of China. Olson's group theory was adopted to explain the timing of the dissolution in a context of uncertainty in the property rights of land; the terms of civil service appointments; and the housing market. The size of the ownership body and the value of the land were evaluated as factors affecting dissolution decisions. It was found that in agreement with Olson's theory, the number of members of the body had a statistically significant positive relationship with the life (between formation and dissolution) of the co-operative body. In addition, it was also found that factors that affected the opportunity cost of maintaining status quo, including the value of the land on which the co-op scheme sits and the real option value of redevelopment, had a significant impact on the timing of the dissolution of the co-op. The implications for using Olson's theory were also discussed. © 2011 Elsevier Ltd.postprin

海浪發電

由於全球人口不斷增長，所以能源需求日益增加。地球上大部份的能源主要來自化石燃料。不過，燃燒化石燃料發電會釋出大量二氧化碳和污染物，造成溫室效應從而導致環境破壞；而且，化石燃料是有限的能源。雖然可用核原料發電，但是核能的安全問題與風險管理不斷受人們爭論。故此，對再生能源的研究及開發是刻不容緩的。本章主要討論其中一種再生能源，海浪發電的好處及近期一些研究成果。published_or_final_versio

Magnetic-field-sensing mechanism based on dual-vortex motion and magnetic noise

published_or_final_versio

Edge effect on thermally excited mag-noise in magnetic tunnel junction sensors

Session AP - Magnetic Tunnel Junctions and Spin Valves (Poster Session): no. AP-14This journal issue contains selected papers from the 2012 International Magnetics (INTERMAG) ConferenceThermally excited magnetic noise (mag-noise) has gradually become a major concern in magnetic tunnel junction sensors. By conducting micromagnetic simulation, the spatial distribution of thermal mag-noise in the free layer (FL) was obtained under various hard bias (HB) field and applied field. It was demonstrated that the edges are the main contributor of thermal mag-noise in the FL. This result could be explained by the nonuniform distribution of the stiffness field around the edges. It was also found that both HB field and applied field could suppress the thermal mag-noise in edges. A relatively high applied field will decrease the influence of HB field on mag-noise in the edges. © 2012 IEEE.published_or_final_versionThe IEEE International Magnetics Conference (INTERMAG 2012), Vancouver, BC., 7-11 May 2012. In IEEE Transactions on Magnetics, 2012, v. 48 n. 11, p. 2831-283

Can the colour of per-rectal bleeding estimate the risk of lower gastrointestinal bleeding caused by malignant lesion?

PURPOSE: To estimate the risk of lower gastrointestinal bleeding (LGIB) caused by malignant lesion in patients presenting with per-rectal bleeding (PRB), by using visual aid as an objective measurement of PRB colour. METHODS: This was a prospective observational study on patients presented with PRB to Family Medicine Specialty Clinic, who undergo flexible sigmoidoscopy (FS) or colonoscopy (CLN) from December 2012 to September 2013. Patients aged 40 years old or above, haemodynamically stable, with normal haemoglobin level were included. Patients with a history of previous colonic surgery, refused to have FS or CLN, with ophthalmologic diseases such as colour blindness were excluded. Parameters including subjective description of PRB colour, number of chosen red colour by patients, source and distance of bleeding from anal verge were recorded for analysis. Receiver operating characteristic (ROC) curve was used to identify the optimal cutoff level of colour for diagnosing colonic lesion. Diagnostic accuracy was assessed by area under the ROC curve (AUC). Accountability of this model was assessed by logistic regression. RESULTS: The dark PRB colour was associated with diagnosis of tumour (p < 0.001) and advanced neoplastic polyp (p < 0.001). The light PRB colour was associated with the diagnosis of piles (p < 0.001). The performance of our model to predict tumour or advanced neoplastic polyps by colour (AUC, 0.798) had a better discriminative power than that to predict colonic lesion alone (AUC, 0.610) by ROC curve analysis. CONCLUSION: Objective measurement of PRB colour accurately estimated the risk of LGIB caused by malignant lesion in patients presenting with PRB.postprin

Thermally Excited Mag-Noise in Ferromagnetic Ring Structures

Session PE: Spin Dynamics and MicromagneticsAs the dimension of magnetic devices drastically decreases to nanometer range, thermally excited mag-noise gradually becomes the dominant noise source. Thermally excited mag-noise plays an important role in ferromagnetic ring structures. By conductingmicromagnetic simulation, the saturated state, triangle state, half triangle state, onion state, and vortex state are explored and studied, respectively. The mag-noise calculation shows that triangle state is the main reason for the mag-noise exhibiting tendency in both the low-frequency range and high-frequency range in relaxed state, while the onion state explains why a noise peak appears in high-frequency range in relaxed state. Meanwhile, it is proved that the area of the ferromagnetic rings is not the determining factor for the mag-noise distribution in saturated state. These results offer the theoretical framework for explaining the relation between domain structure and mag-noise, which is conducive to the future application of ferromagnetic ring structures as magnetic random access memory elements.published_or_final_versio