The Arithmetic of Calabi--Yau Manifolds and Mirror Symmetry

We study mirror symmetric pairs of Calabi--Yau manifolds over finite fields. In particular we compute the number of rational points of the manifolds as a function of the complex structure parameters. The data of the number of rational points of a Calabi--Yau $X/\mathbb{F}_q$ can be encoded in a generating function known as the congruent zeta function. The Weil Conjectures (proved in the 1970s) show that for smooth varieties, these functions take a very interesting form in terms of the Betti numbers of the variety. This has interesting implications for mirror symmetry, as mirror symmetry exchanges the odd and even Betti numbers. Here the zeta functions for a one-parameter family of K3 surfaces, $\mathbb{P}_3[4]$, and a two-parameter family of octics in weighted projective space, $\mathbb{P}_4{}^{(1, 1, 2, 2, 2)} [8]$, are computed. The form of the zeta function at points in the moduli space of complex structures where the manifold is singular (where the Weil conjectures apart from rationality are not applicable), is investigated. The zeta function appears to be sensitive to monomial and non-monomial deformations of complex structure (or equivalently on the mirror side, toric and non-toric divisors). Various conjectures about the form of the zeta function for mirror symmetric pairs are made in light of the results of this calculation. Connections with $L$-functions associated to both elliptic and Siegel modular forms are suggested.Comment: Oxford University DPhil thesis, 199 pages, 28 figure

Fire detection of Unmanned Aerial Vehicle in a Mixed Reality-based System

This paper proposes the employment of a low-cost Micro-electro-mechanical system including; inertial measurement unit (IMU), a consumer-grade digital camera and a fire detection algorithm with a nano unmanned aerial vehicle for inspection application. The video stream (monocular camera) and navigation data (IMU) rely on state-of-the-art indoor/outdoor navigation system. The system combines robotic operating system and computer vision techniques to render metric scale of monocular vision and gravity observable to provide robust, accurate and novel inter-frame motion estimates. The collected onboard data are communicated to the ground station and processed using a Simultaneous Localisation and Mapping (SLAM) system. A robust and efficient re-localisation SLAM was performed to recover from tracking failure, motion blur and frame lost in the received data. The fire detection algorithm was deployed based on the colour, movement attributes, temporal variation of fire's intensity and its accumulation around a point. A cumulative time derivative matrix was used to detect areas with fire's high-frequency luminance flicker (random characteristic) to analyse the frame-by-frame changes. We considered colour, surface coarseness, boundary roughness and skewness features while the quadrotor flies autonomously within clutter and congested areas. Mixed Reality system was adopted to visualise and test the proposed system in a physical/virtual environment. The results showed that the UAV could successfully detect fire and flame, fly towards and hover around it, communicate with the ground station and generate SLAM system

Effectiveness of Surf Therapy for Children with Disabilities

Background: Few researchers have examined the effects of surf programs on children with disabilities. Due to previous research findings, surfing is being used, as the focus of physical activity intervention due to its numerous health and therapeutic benefits. Objective/Hypothesis: The purpose of this study was to explore the effects of an eight-week surfing intervention on various physical fitness measures in 71 children with disabilities such as autism spectrum disorder, down syndrome, global developmental delays, and cerebral palsy. The study also sought to compare the differences in overall fitness levels between the surf therapy group and an unstructured pool playgroup. Researchers predicted significant differences in the surf therapy group. Methods: The assessment procedure consisted of pre and post physical fitness measures selected from the Brockport Physical Fitness Test in two groups: surfing (n=71) and an unstructured aquatic program (n=20). Results: The results demonstrated significant improvements in core strength (p = 0.00), upper body strength (p = 0.00), flexibility (p = 0.01) and cardiorespiratory endurance (p = 0.00) in the surfing group. However, there were no significant differences in overall fitness levels between the surfing and unstructured pool playgroups. Body composition measurements on the surfing group demonstrated a significant reduction in total body fat % (p = 0.016) and fat free mass (p = 0.008) and a significant improvement in bone mineral density (p = 0.004) pre to post surf therapy. Conclusions: This research demonstrated the effectiveness and physiological benefits of surf therapy for children with selected disabilities

High-dimensional cluster analysis with the masked EM algorithm

This is an Open Access article published under a Creative Commons Attribution 3.0 Unported (CC BY 3.0) license https://creativecommons.org/licenses/by/3.0/Cluster analysis faces two problems in high dimensions: the "curse of dimensionality" that can lead to overfitting and poor generalization performance and the sheer time taken for conventional algorithms to process large amounts of high-dimensional data. We describe a solution to these problems, designed for the application of spike sorting for nextgeneration, high-channel-count neural probes. In this problem, only a small subset of features provides information about the cluster membership of any one data vector, but this informative feature subset is not the same for all data points, rendering classical feature selection ineffective.We introduce a "masked EM" algorithm that allows accurate and time-efficient clustering of up to millions of points in thousands of dimensions. We demonstrate its applicability to synthetic data and to real-world high-channel-count spike sorting data.Peer reviewe

An efficient hybrid method for 3D to 2D medical image registration

PURPOSE: The purpose of this paper is to present a method for registration of 3D computed tomography to 2D single-plane fluoroscopy knee images to provide 3D motion information for knee joints. This 3D kinematic information has unique utility for examining joint kinematics in conditions such as ligament injury, osteoarthritis and after joint replacement. METHODS: We proposed a non-invasive rigid body image registration method which is based on two different multimodal similarity measures. This hybrid registration method helps to achieve a trade-off among different challenges including, time complexity and accuracy. RESULTS: We performed a number of experiments to evaluate the performance of the proposed method. The experimental results show that the proposed method is as accurate as one of the most recent registration methods while it is several times faster than that method. CONCLUSION: The proposed method is a non-invasive, fast and accurate registration method, which can provide 3D information for knee joint kinematic measurements. This information can be very helpful in improving the accuracy of diagnosis and providing targeted treatment

The interplay between formal and informal elements in analysing situations of role conflict among construction participants

The interplay of formal and informal factors in construction teams influences the enactment of roles and the individuals who fulfil those roles. With a specific focus on a phenomenon called role conflict, the aim is to explore if and how the interaction of formal and informal elements would lead to situations of role conflict. This phenomenon proved to lead to frustration, tension and employee burnout. An analytical model of role interaction was developed, which disentangles formal and informal elements that shape role interactions. Qualitative data was collected through semi-structured interviews, project documents and observations. Four cases of role conflict are presented here. Contract, as a formal element, and participant’s values and interests, as informal elements, appeared to be the most important factor shaping participants’ expectations and behaviours. The analysis in this study showed that if a participant who faces role conflict is able to influence the formal elements in favour of his or her informal elements, then he or she may experience less frustration. At a more general level, the results suggest that increasing formality can increase participants’ frustration, which then would decrease the likelihood of collaboration. As the theoretical contribution, this research extends organizational role theory to deal with informal and formal aspects. Taking into account formal sources enables the study of how roles are institutionally governed while including informal sources allows for the idea that some of the aspects of the role, even in the context of work role, are socially constructed

Environmental aspects of the combined cooling, heating, and power (CCHP) systems: a review

© 2022 The Authors. Published by MDPI AG. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.3390/pr10040711Expanding cities means increasing the need for energy in the residential sector. The supply of this energy must be in environmentally friendly ways; one method of meeting demand in the residential sector is the use of combined cooling, heating, and power (CCHP) systems. The current review paper shows that due to the high cost of gas and electricity, CCHP can be used in various sectors, such as hospitals and airports, to reduce energy consumption with lower environmental impacts by using renewable energy systems as the main driver. While CCHP systems are not feasible in tropical regions with high cooling demand, a solar hybrid system is a superior candidate for regions with sufficient radiation. CCHP can also be used in sectors such as wastewater treatment units, desalination systems, and hydrogen production units to improve performance and increase productivity. The carbon and water footprints of CCHP systems are discussed in detail. The main drivers for reducing carbon and water footprints are improving system components such as the combustion engine and increasing productivity by expanding the system to multi-generation systems. Finally, the carbon tax index can help reduce carbon emissions if properly used in the right context. Based on our best knowledge, there is no extensive review of the environmental aspects of CCHP systems in the literature.Published versio