The physics of negative refraction and transformation optics

Whilst optics is one of the oldest field in science, there are still aspects of electromagnetism that we are only beginning to uncover. For instance, it was demonstrated that materials with simultaneously negative permittivity and permeability exhibit certain exotic behavior; where familiar physical phenomena, such as refraction, are reversed. As such, these materials came to be known as negative refractive index materials (NRIM) and their collective properties as negative refraction. One of the most important and remarkable property of NRIM is perfect lensing - the ability to transport both supra and sub-wavelength optical information from one surface (object plane) to another (image plane), forming images with unprecedented resolution, beyond the diffraction limit. Perfect lensing itself is a consequence of deeper symmetries in electromagnetism, encapsulated in the language of transformation optics - with which we have both a descriptive tool to unify diverse electromagnetic configuarations, as well as a prescriptive tool to design media which bends light at will. While, such transformation medium and NRIM have been demonstrably realised using metamaterials, several challenges remain, of which loss is the major challenge. It is therefore under this trinity of concepts: metamaterials, negative refraction and transformation optics that this thesis is presented. In particular, this thesis illustrates the convergence of the later two concepts, giving rise to a novel class of perfect lens - the compact perfect lens. Here, we shall investigate, their unique properties, construction, challenges, and the dynamics of these lenses. In particular the formulation to study dynamics and effects of losses, is universal; applicable to lenses of any geometry. Finally we shall also propose an alternative universal, top-down approach to overcome losses in perfect lenses using phase conjugation, and demonstrate the capacity of such lenses to see through lossy, translucent obstacles

Lattice constants, thermal expansion coefficients and perfection of the phase TiO

TiO is one of the intermediate phases in the titanium - oxygen system with a crystal structure of the sodium chloride type. The phase extends from about 22 to 29 weight or about 46 to 55 atomic percent oxygen. A comprehensive survey of the physical properties of the phase has been made in previous investigations (see review of literature), but only impure titanium was available at that time. Therefore, some revision of the measurements had to be made. Also, neither the thermal expansion coefficients nor the temperature at which the lattice constants were measured were reported. For precision determination of lattice parameters, the purity of the material to be used is extremely important. As TiO has a wide range of solid solubility, both with titanium and oxygen, it is very difficult to prepare a sample which has an exact TiO composition. So, about five samples of different composition within the range of the TiO phase were prepared and analyzed. The precise lattice parameter of each sample was determined by the x-ray asymmetric powder method at temperature intervals of ten degrees between about 16°C and 60°C. This method allows one to determine: (1) The thermal expansion coefficient: this is calculated from the lattice parameter - temperature plots, as the slope of the line, representing the linear expansion coefficients of the sample, can be easily determined. (2) The lattice constants of the samples at 25°C: from the lattice constant - temperature plots, the constants at 25°C can be read. (3) The effect of composition on the lattice parameter of the TiO phase: by plotting the lattice parameter of the samples at 25°C against their compositions. ( 4) The precise lattice parameter of pure TiO at 25°C: from the lattice parameter - composition plot the precise lattice parameter of TiO can be read. Finally, determining the densities of the samples, using the method described by Aka, the soundness of the crystal lattice of TiO solid solution can be evaluated --Introduction, pages 1-2

Understanding Software-as-a-Service Performance - A Dynamic Capability Perspective

How to increase a client’s capability through outsourcing remains a problem. This papers draws on strategic management literature and the relational view to develop a theoretical model that explains the relationships between collaboration, agility, and outsourcing performance in software-as-a-service (SaaS) context. Collaboration are characterized as knowledge sharing and process alignment between a supplier and its client, agility as a supplier’s sensing agility and responding agility. This study also investigates the moderating effect of environmental turbulence on the relationships between agility and performance. The proposed hypotheses are largely supported by the empirical data from 215 firms. The results show that SaaS performance is affected by both sensing agility and responding ability, which, in turn, are impacted by collaboration between a supplier and its client. Finally, we discuss the implications of our results

Endoscopic Retrograde Cholangiopancreatography in Elderly Patients

SUMMARYEndoscopic retrograde cholangiopancreatography (ERCP) is effective in the investigation and treatment of pan-creatic and biliary disease. As the prevalence of bile duct stones and malignant disease and the risk of surgery rise with age, studies on the therapeutic success of ERCP in the elderly become more popular. There have been publications documenting the safety of ERCP in elderly patients from the age of 65 to 85 years. Recent studies have also shown that ERCP is safe and effective in those aged 90 years and older. Outcomes of ERCP in terms of success and complication rates are similar to those in younger patients. Therefore, the decision to undergo ERCP should be determined by clinical need, and age alone should not be a contraindication to endoscopic intervention. Here, we review the indications, pre-procedure preparation, sedation and analgesia, monitoring/procedural care, complications, and outcomes of diagnostic and therapeutic ERCP in the elderly

Extend the debt as it is not deeply out-of-the-money

In this paper, we modify the extendible debts model proposed in Longstaff (1990) to help relieve the moral hazard problem induced in the original model. In Longstaff¡¦s model, extending the maturity of the defaulted debts gives the borrower an incentive to default even if the borrower is insolvent. In this paper, we argue that the debt should not be extended if it is defaulted severely. We have shown that the extendible debt valuation can be obtained by the compound option pricing besides the PDE approach. We also have derived the fair interest rate of the extendible debts in this paper.

Intraprofessional Collaboration in Learning Evidence-Based Practice

Little is known about how collaborative curricular activities can help students learn about scientific evidence in occupational therapy (OT) and occupational therapy assistant (OTA) programs. We created and measured collaborative learning in evidence-based practice activities to enhance partnership building and intraprofessional collaboration among students in OT and OTA programs. Thirty-three OT students and 26 OTA students enrolled in a didactic course (Phase I) and an intraprofessional collaborative learning activity (Phase II) participated in this quasi-experimental repeated measure study. The students’ ability of how to read scholarly articles and their perceived importance and perceived ability to engage in intraprofessional collaboration were examined at three time points. Improvements were found in the OT students’ perceived importance of intraprofessional roles/responsibilities and the OTA students’ perceived ability to engage in intraprofessional communication after completing the Phase I didactic course. Both the OT and OTA students’ perceived ability to work as a team, identify their roles/responsibilities, communicate with peers, and their ability to read scholarly articles improved after the Phase II intraprofessional collaboration. Students valued the opportunity to gain collaboration experience and share different perspectives. They indicated they would have preferred to spend more time on the activities. The findings suggest that targeted learning activities can improve OT and OTA students’ ability to engage in evidence-based practice and their perceived importance and ability to engage in intraprofessional collaboration. Effective partnerships and intraprofessional collaboration are best introduced within academic programs

Performance-based Fire Safety Design for Existing Small-scale Hospitals

AbstractThe new era of National Health Insurance in 2000 has had a significant impacted on the management and operation of smallscale hospitals. In response to social needs, and in order to survive under the new insurance system, some small-scale hospitals have transformed or established new Respiratory Care Wards by using existing hospital space. According to the 2009 statistics released by Department of Health, Executive Yuan, there are a total of 307 small-scale medical institutes which provide servicesunder 99 beds. Compared with other large-scale medical centers and general hospitals, small-scale hospitals cannot properly deal with safety management and response to emergency evacuation due to lack of facilities, equipment and human resources. Therefore, small-scale hospitals face a major challenge in emergency response once a fire has occurred. As a result of such a situation, this study has focused mainly on Respiratory Care Wards (RCW) where patients are unable to evacuate. It hopes to analyse the safety management, and emergency response in small-scale hospitals by means of understanding the space characteristics and fire risk. Through on-site surveys, we can understand the fire risk, space features, patient characteristics, facilities and equipment. With reference to the related regulations of hospital emergency management and response, we will propose some fire safety engineering approaches, such as refuge areas in horizontal evacuation and so-called “besieged zones” for “defense-in-place”, etc., to provide some alternative measures to improve fire safety for those small-scale hospitals

Understanding Outsourcing Commitment—An Integrated Model Combining The Resoruce-Based View And Knowledge Management

The understanding on how a service provider’s (SP) process capabilities, in terms of aligning and adapting resources to deliver value to its service recipient (SR) in business process outsourcing (BPO), affect its commitment is limited. To address this, building on a strategic perspective and related theories such as the resource-based view and knowledge management, we develop a theoretical model and test it empirically. Specifically, we posit that a SP’s process capabilities, in terms of process alignment, offering flexibility, and partnering flexibility, positively affect its SR’s commitment and the above relationships is negatively moderated by the SR’s behavior control. Besides, we also examine the influence of interaction effect between antecedents of process capabilities on commitment, such as how does process alignment interact with its partnering flexibility and offering flexibility to affect commitment. Finally, we assess whether process capabilities are influenced by the SR’s absorptive capacity and the SP’s task-knowledge coordination. We test our model using survey data collected from 183 firms, supporting most proposed hypotheses. We discuss the theoretical and practical implications of how to increase the value offered to a SR by levering resources, in terms of process capabilities and knowledge management