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Educationally, we are in an exciting time in terms of geometrical investigations in the classroom. While the manipulation of concrete materials to enable student construction of two-dimensional figures and three-dimensional objects has been readily available for many years, there are a growing number of mathematics classrooms that have access to dynamic geometry software and interactive sites that enable real-time creation and exploration of geometric figures and their properties. In fact, in some pockets of society, students’ access to a mobile device is in a similar manner to how classrooms of the 1980s used pen and paper as a resource. While, in jest, mobile devices may be referred to ‘an extension of the brain’, in its regular use as an instant source of information and exploration there is an element of this use that can be exploited for positive gain in the mathematics classroom. This chapter explores the development of geometrical concepts and the manner in which we can facilitate exploratory experiences to assist students in their development.
By combining multiple input multiple output (MIMO) technology and multiple matched filters with frequency diverse array (FDA), FDA-MIMO radar can be used to achieve two-dimensional target localization with range and angle. In this paper, we propose two FDA-MIMO multi-pulse target localization methods based on tensor decomposition. Based on the canonical polyadic decomposition theory, the signal models of CPD-DP-FDA with double-pulse and CPD-SP-FDA with stepped frequency pulses are established. By analyzing the signal processing procedures of the two schemes, the indicator beampattern used for target localization is obtained. The parameter estimation accuracy of the proposed method is investigated in single target and multiple targets scenarios, and the proposed method is compared with the traditional double-pulse method. The results show that the target localization method based on tensor decomposition can effectively solve the problem of multi-target indication ambiguity. The target positioning effect can be further improved by combining stepped frequency pulses. The derivation of Cramer–Rao Lower Bound (CRLB) demonstrates the superiority of the method.
Three-dimensional endoscopes provide a stereoscopic view of the operating field, facilitating depth perception compared to two-dimensional systems, but are not yet widely accepted. Existing research addresses performance and preference, but there are no studies that quantify anatomical orientation in endoscopic ear surgery.
Methods
Participants (n = 70) were randomised in starting with either the two-dimensional or three-dimensional endoscope system to perform one of two tasks: anatomical orientation using a labelled three-dimensional printed silicone model of the middle ear, or simulated endoscopic skills. Scores and time to task completion were recorded, as well as self-reported difficulty, confidence and preference.
Results
Novice surgeons scored significantly higher in a test of anatomical orientation using three-dimensional compared to two-dimensional endoscopy (p < 0.001), with no significant difference in the speed of simulated endoscopic skills task completion. For both tasks, there was lower self-reported difficulty and increased confidence when using the three-dimensional endoscope. Participants preferred three-dimensional over two-dimensional endoscopy for both tasks.
Conclusion
The findings demonstrate the superiority of three-dimensional endoscopy in anatomical orientation, specific to endoscopic ear surgery, with statistically indistinguishable performance in a skills task using a simulated trainer.
Chapter 5 is mainly devoted to the interaction between waves and immersed bodies. In general, an immersed body may oscillate in six different modes, three translating modes (surge, sway, heave) and three rotating modes (roll, pitch, yaw). An oscillating body radiates waves, and an incident wave may induce a corresponding excitation force for each one of the six modes. When a body oscillates, it radiates waves. Such radiated waves and excitation forces are related by so-called reciprocity relationships. Such relations are derived not only for a single oscillating body but even for a group (or 'array') of immersed bodies. Axisymmeric bodies and two-dimensional bodies are discussed in separate sections of the chapter. Although most of this chapter discusses wave-body dynamics in the frequency domain, a final section treats an immersed body in the time domain.
Chapter 8 concerns a group of WEC units that may be realised in a more distant future, namely groups or arrays of individual WEC units and two-dimensional WEC units, which needs to be rather big structures. Firstly, a group of WEC bodies is analysed. Next a group consisting of WEC bodies as well as OWCs is analysed. Then the previous real radiation resistance needs to be replaced by a complex radiation damping matrix which is complex, but Hermitian, which means that its eigenvalues are real.
A formal result is proved which is used in Juhani Yli-Vakkuri's ‘Epistemicism and Modality’ to argue that certain two-dimensional possible world models are inadequate for a language with operators for ‘necessarily’, ‘actually’, and ‘definitely’.
Two-dimensional pyrite crystals (40–80 µm wide and 2–3 µm thick) and large thin crusts are reported from the mudstones from the Carboniferous coal basin in Poland. Crystals occur on a flat surface, originally probably a crack in the rock, and are composed of uniform particles (150–200 nm wide). A hypothetical pathway of the formation of 2D pyrite crystals is presented: (1) formation of pyrite particles (or monosulphide precursors) in the suspension introduced onto the surface of the crack, and forming a film with a smooth meniscus at the air/suspension interface on the rock substrate; (2) thinning of the suspension film due to the water loss, increase of particle concentration, and formation of the first monolayers; (3) growth leading to the formation of thin crystals complying with pyrite crystallography.
Traditional methods for the assessment of dietary intake are prone to error; in order to improve and enhance these methods increasing interest in the identification of dietary biomarkers has materialised. Metabolomics has emerged as a key tool in the area of dietary biomarker discovery and to date the use of metabolomics has identified a number of putative biomarkers. Applications to identify novel biomarkers of intake have in general taken three approaches: (1) specific acute intervention studies to identify specific biomarkers of intake; (2) searching for biomarkers in cohort studies by correlating to self-reported intake of a specific food/food group(s); (3) analysing dietary patterns in conjunction with metabolomic profiles to identify biomarkers and nutritypes. A number of analytical technologies are employed in metabolomics as currently there is no single technique capable of measuring the entire metabolome. These approaches each have their own advantages and disadvantages. The present review will provide an overview of current technologies and applications of metabolomics in the determination of new dietary biomarkers. In addition, it will address some of the current challenges in the field and future outlooks.
The two-sided nonlinear boundary crossing probabilities for one-dimensional Brownian motion and related processes have been studied in Fu and Wu (2010) based on the finite Markov chain imbedding technique. It provides an efficient numerical method to computing the boundary crossing probabilities. In this paper we extend the above results for high-dimensional Brownian motion. In particular, we obtain the rate of convergence for high-dimensional boundary crossing probabilities. Numerical results are also provided to illustrate our results.
Structural development of BPDA-PPD polyimide thin film has been investigated by in situ grazing incidence X-ray diffraction at the BL24XU beamline of the SPring-8. Optimizing the sample shape, two-dimensional images were measured successfully without sacrificing angle resolution. It has been clearly shown that the crystallization first begins in the in-plane direction, at the curing temperature of 180 °C, in which the periodic structure of the molecular chain axis (c axis) is developed. The crystallization in the surface normal (out-of-plane) direction is observed later, at the curing temperature above 300 °C. A slight increase of the d spacing of the c axis during heating process has been observed, suggesting the stretching of the contracted molecular chain in accordance with the curing process. In the cooling process, the decrease of the d spacings for a and b axes was considerable, which indicates thermal expansion of the crystals at high temperatures. The increases in the peak intensities during the cooling process have been observed, which indicate the d spacing of each axis becomes close to the equilibrium value to produce higher periodicity.
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