Wright-Fisher diffusion bridges

The trajectory of the frequency of an allele which begins at $x$ at time $0$ and is known to have frequency $z$ at time $T$ can be modelled by the bridge process of the Wright-Fisher diffusion. Bridges when $x=z=0$ are particularly interesting because they model the trajectory of the frequency of an allele which appears at a time, then is lost by random drift or mutation after a time $T$. The coalescent genealogy back in time of a population in a neutral Wright-Fisher diffusion process is well understood. In this paper we obtain a new interpretation of the coalescent genealogy of the population in a bridge from a time $t\in (0,T)$. In a bridge with allele frequencies of 0 at times 0 and $T$ the coalescence structure is that the population coalesces in two directions from $t$ to $0$ and $t$ to $T$ such that there is just one lineage of the allele under consideration at times $0$ and $T$. The genealogy in Wright-Fisher diffusion bridges with selection is more complex than in the neutral model, but still with the property of the population branching and coalescing in two directions from time $t\in (0,T)$. The density of the frequency of an allele at time $t$ is expressed in a way that shows coalescence in the two directions. A new algorithm for exact simulation of a neutral Wright-Fisher bridge is derived. This follows from knowing the density of the frequency in a bridge and exact simulation from the Wright-Fisher diffusion. The genealogy of the neutral Wright-Fisher bridge is also modelled by branching P\'olya urns, extending a representation in a Wright-Fisher diffusion. This is a new very interesting representation that relates Wright-Fisher bridges to classical urn models in a Bayesian setting. This paper is dedicated to the memory of Paul Joyce

Backpropagating constraints-based trajectory tracking control of a quadrotor with constrained actuator dynamics and complex unknowns

In this paper, a backpropagating constraints-based trajectory tracking control (BCTTC) scheme is addressed for trajectory tracking of a quadrotor with complex unknowns and cascade constraints arising from constrained actuator dynamics, including saturations and dead zones. The entire quadrotor system including actuator dynamics is decomposed into five cascade subsystems connected by intermediate saturated nonlinearities. By virtue of the cascade structure, backpropagating constraints (BCs) on intermediate signals are derived from constrained actuator dynamics suffering from nonreversible rotations and nonnegative squares of rotors, and decouple subsystems with saturated connections. Combining with sliding-mode errors, BC-based virtual controls are individually designed by addressing underactuation and cascade constraints. In order to remove smoothness requirements on intermediate controls, first-order filters are employed, and thereby contributing to backstepping-like subcontrollers synthesizing in a recursive manner. Moreover, universal adaptive compensators are exclusively devised to dominate intermediate tracking residuals and complex unknowns. Eventually, the closed-loop BCTTC system stability can be ensured by the Lyapunov synthesis, and trajectory tracking errors can be made arbitrarily small. Simulation studies demonstrate the effectiveness and superiority of the proposed BCTTC scheme for a quadrotor with complex constrains and unknowns

Fast and accurate trajectory tracking control of an autonomous surface vehicle with unmodeled dynamics and disturbances

In this paper, fast and accurate trajectory tracking control of an autonomous surface vehicle (ASV) with complex unknowns including unmodeled dynamics, uncertainties and/or unknown disturbances is addressed within a proposed homogeneity-based finite-time control (HFC) framework. Major contributions are as follows: (1) In the absence of external disturbances, a nominal HFC framework is established to achieve exact trajectory tracking control of an ASV, whereby global finitetime stability is ensured by combining homogeneous analysis and Lyapunov approach; (2) Within the HFC scheme, a finite-time disturbance observer (FDO) is further nested to rapidly and accurately reject complex disturbances, and thereby contributing to an FDO-based HFC (FDO-HFC) scheme which can realize exactness of trajectory tracking and disturbance observation; (3) Aiming to exactly deal with complicated unknowns including unmodeled dynamics and/or disturbances, a finite-time unknown observer (FUO) is deployed as a patch for the nominal HFC framework, and eventually results in an FUO-based HFC (FUOHFC) scheme which guarantees that accurate trajectory tracking can be achieved for an ASV under harsh environments. Simulation studies and comprehensive comparisons conducted on a benchmark ship demonstrate the effectiveness and superiority of the proposed HFC schemes

An investigation of School-Based Curriculum Development in Chinese state-run high schools: A multi-cases study on curriculum leadership and teacher participation

This study aims to investigate the implementation of SBCD in high school context of mainland China based on Marsh’s matrix of SBCD variations (1990; 2009). It also investigates the roles and responsibilities of school leaders and teachers in the process of implementation. Most empirical studies in the field have been written in primary and middle school contexts, but few studies were carried out at high schools with a deep consideration of the Chinese University Entrance Examination (UEE). As the fact that UEE has long been deeply embedded in Chinese high school context, little is known about how UEE would affect the implementation of SBCD.A mixed-method design was used to collect and analyse the study data in two state-run high schools of mainland China. The aim of using both quantitative and qualitative data collection tools is to illuminate the way leaders and teachers implement SBCD in a high school, and how they implement and understand the SBCD to afford the existing school structure in relation to the school needs and improvement. Data were collected sequentially according to the explanatory sequential design. In the first phase of the study, a questionnaire was employed to investigate the whole teacher population of two focused schools. In the second phase, 20 participants including leaders and teachers were interviewed through a semi-structured interview. Descriptive statistics and thematic analysis were undertaken.Eight themes with twenty associated sub-themes were identified from the analysis. The findings indicated that the implementation of SBCD mainly depended on the school culture, history and leadership. The results revealed two leader roles and three main responsibilities in leading SBCD, and two different patterns of teacher participation in SBCD such as individual with self-actualisation and passive with a lack of agency. Also, this study confirmed a dilemma of SBCD caused by long-standing traditional exam culture in Chinese state-run high schools.</div

Robust reinsurance contracts with risk constraint

This thesis investigates a class of optimal reinsurance contract problems in continuous time. We use the principal-agent framework to incorporate the bargaining between the insurer and the reinsurer. To this end, we extend the reinsurer's relative safety loading factor which is usually a pre-specified constant in the traditional expected value principle to be time-varying and to represent the reinsurance premium. Since the insurance companies should satisfy the regulators' capital requirements and the computation of capital requirements is based on Value-at-Risk (VaR) under Solvency II regime, we introduce the dynamic version of VaR andimpose a dynamic VaR constraint on the insurer. As for the reinsurer, we assumethat she is ambiguity-averse and aims to maximize the expected utility of herterminal wealth under the worst-case scenario of the alternative measures. The dynamic programming technique is applied to derive the principal's Hamilton-Jacobi-Bellman-Isaacs (HJBI) equation and the agent's Hamilton-Jacobi-Bellman(HJB) equation. Additionally, Karush-Kuhn-Tucker (KKT) conditions are utilized to settle the constrained optimization problem of the agent. Explicit expressions for the optimal retained proportional of the claims, the optimal reinsurance premium and the corresponding value functions of the insurer and the reinsurer are derived. Finally, we analyze several numerical examples to illustrate economic intuition. Our results show that the reinsurer's ambiguity aversion and the insurer's risk constraint increase the optimal reinsurance premium, which decreases the optimal reinsurance demand of the insurer

Consumer-oriented incoming call connection service for the ubiquitous consumer wireless world

This thesis proposes a novel consumer-oriented Incoming Call Connection (ICC) service as an important enabling infrastructural component of the recently proposed ubiquitous consumer wireless world (UCWW), a new Consumer-centric Business Model (CBM) environment for wireless communications. The ICC solution proposed here will be offered by third-party providers who are autonomous of the access network providers. Compared to the present ICC service in the legacy subscriber-based networks, the consumeroriented ICC service will offer to mobile users greater flexibility and management control over incoming calls, enable users to receive incoming calls via multiple access networks/providers by means of a single identity, support user-driven, seamless, network-transparent Hot Access network Change (HAC), largely eliminate roaming charges and develop a new wireless networking business opportunity among other benefits. This thesis advocates for a coming paradigm change from the existing ICC service established on the Subscriber-based Business Model (SBM-ICC) towards the CBM-based ICC (CBM-ICC) service. The investigation, design and implementation of all the protocols and other elements required for building the CBM-ICC service especially in terms of transport, signaling and mobility support are addressed. The existence of other key UCWW infrastructural components of third-party authentication, authorization and accounting (3P-AAA) service provision, IPv6 personal address, and service offerings advertisements over wireless billboard channels (WBCs) is assumed. An architecture and protocol infrastructure for the CBMICC service is elaborated. Components and interfaces relying upon existing protocols or requiring new signaling protocols (or modification/new elements of existing protocols) are identified and for the latter solutions are suggested. The concept of user-driven HAC is promoted and described. The introduction of the Stream Control Transmission Protocol (SCTP) as a potential solution for enabling this HAC is motivated. Furthermore, the thesis elaborates a generic CBM-ICC service scenario, which shows how the CBM-ICC service offers to mobile users greater freedom and operation control over incoming calls, enables the novel attribute of users being empowered to receive incoming calls simultaneously, and otherwise, from various homogeneous and heterogeneous access networks, owned by the same or different providers, and enables user-driven HAC on active calls in keeping with, or matched to, user’s Always Best Connected and Best Served (ABC&S) policies. A CBM-ICC proof-of-concept system-level testbed is implemented to perform experimental tests, probe different communications scenarios, evaluate the service performance, and further elaborate the service architecture. In this, approaches towards evaluating the performance of the CBM-ICC service based on designed testbed are elaborated, and sample numerical results are presented and analyzed

Consumer-oriented incoming call connection service for the ubiquitous consumer wireless world

This thesis proposes a novel consumer-oriented Incoming Call Connection (ICC) service as an important enabling infrastructural component of the recently proposed ubiquitous consumer wireless world (UCWW), a new Consumer-centric Business Model (CBM) environment for wireless communications. The ICC solution proposed here will be offered by third-party providers who are autonomous of the access network providers. Compared to the present ICC service in the legacy subscriber-based networks, the consumeroriented ICC service will offer to mobile users greater flexibility and management control over incoming calls, enable users to receive incoming calls via multiple access networks/providers by means of a single identity, support user-driven, seamless, network-transparent Hot Access network Change (HAC), largely eliminate roaming charges and develop a new wireless networking business opportunity among other benefits. This thesis advocates for a coming paradigm change from the existing ICC service established on the Subscriber-based Business Model (SBM-ICC) towards the CBM-based ICC (CBM-ICC) service. The investigation, design and implementation of all the protocols and other elements required for building the CBM-ICC service especially in terms of transport, signaling and mobility support are addressed. The existence of other key UCWW infrastructural components of third-party authentication, authorization and accounting (3P-AAA) service provision, IPv6 personal address, and service offerings advertisements over wireless billboard channels (WBCs) is assumed. An architecture and protocol infrastructure for the CBMICC service is elaborated. Components and interfaces relying upon existing protocols or requiring new signaling protocols (or modification/new elements of existing protocols) are identified and for the latter solutions are suggested. The concept of user-driven HAC is promoted and described. The introduction of the Stream Control Transmission Protocol (SCTP) as a potential solution for enabling this HAC is motivated. Furthermore, the thesis elaborates a generic CBM-ICC service scenario, which shows how the CBM-ICC service offers to mobile users greater freedom and operation control over incoming calls, enables the novel attribute of users being empowered to receive incoming calls simultaneously, and otherwise, from various homogeneous and heterogeneous access networks, owned by the same or different providers, and enables user-driven HAC on active calls in keeping with, or matched to, user’s Always Best Connected and Best Served (ABC&S) policies. A CBM-ICC proof-of-concept system-level testbed is implemented to perform experimental tests, probe different communications scenarios, evaluate the service performance, and further elaborate the service architecture. In this, approaches towards evaluating the performance of the CBM-ICC service based on designed testbed are elaborated, and sample numerical results are presented and analyzed

Evaluation of quality of paper-based versus electronic nursing documentation in Australian residential aged care homes

Nursing documentation, a major clinical information source in Australian residential aged care, plays a significant role in the management and delivery of care services. In addition to its importance in supporting effective communication between different care team members, high quality nursing documentation is essential to meet accreditation, funding and quality improvement requirements. Electronic nursing documentation systems were implemented in several aged care organisations in an attempt to improve documentation efficiency and utility of data. The effect of the systems on the overall quality of nursing documentation is yet to be validated. In addition, although documentation practice in the aged care sector is generally shaped by legislative requirements, it is unclear how nursing documentation is managed and conducted in reality in different organisations. To our knowledge, limited studies have been conducted in this area internationally and no study has been conducted in Australia. To fill this knowledge gap, this study investigated nursing documentation practices in several Australian residential aged care organisations and compared the quality of nursing documentation between paper-based and electronic documentation systems. A nursing documentation evaluation framework was established by conducting a systematic literature review of documentation quality and its evaluation approaches and, based on this, developing a nursing documentation audit instrument. Three attributes of nursing documentation quality were identified in the review and addressed by the audit instrument. These are the structure and format, process and content of nursing documentation. The audit instrument addresses different components of nursing documentation in a resident record which follow the five steps of the nursing process model: assessment, problem/diagnosis, goal, intervention and evaluation. Applying the audit instrument, four nursing documentation audit studies were conducted in nine residential aged care facilities belonging to three aged care organisations. The first study focused on the resident admission forms. The overall completeness and comprehensiveness rates varied significantly among different versions of forms and both rates were higher in the electronic than in the paper-based forms. A comparison was also made for common items, showing higher completeness and comprehensiveness rates in the electronic forms than in their paper-based counterparts. A correlation analysis showed a negative association between the number of items in a form and its completeness rate, but a positive association between the number of items in a form and its comprehensiveness rate. The second study addressed resident assessment forms. Varying practices of documentation of assessment were found among the three organisations. On average, the quantity of assessment forms was higher in the electronic than in the paper-based records. No improvement was found in the electronic systems in regard to the completeness and timeliness of nursing assessment documentation, but the comprehensiveness of assessment forms was increased in the electronic systems. There was a similar pattern of assessment documentation assigned to various defined assessment categories for both types of systems. The third study assessed the quality of paper-based and electronic resident nursing care plans (NCPs). Free-text NCPs were found in two organisations and standardized NCPs were found in the other. Various terms were used to label the four sections of the NCPs. The amount of information used to describe a resident problem was higher in the electronic free-text than in the paper-based NCPs. An analysis at the level of each step of the nursing process showed a significant difference between the paperbased and electronic systems in the description of nursing diagnosis/problem in both free-text and standardized NCPs. The final study compared the quality of documentation structure, format and process between the paper-based and electronic resident records. The results of assessment by 10 relevant questions in the instrument suggested a higher mean total score for each electronic than for each paper-based record. This research revealed that the electronic documentation systems appear to generate better data than the paper-based systems in terms of documentation structure, format and process. The content of nursing documentation could be determined by complex underlying factors. To meet care, management and nursing development needs, electronic documentation systems need to be integrated seamlessly with other relevant factors to improve documentation practice and quality in residential aged care

Data for: Spherical Montmorillonite-Supported Silver Nanoparticles as a Self-Sedimentary Catalyst for Methylene Blue Removal

All the figures dealed with softwore Origin

Appendix and data files

Appendix 1 and 2 were used in the main text. Four original data files were used to conduct the analyses