New Perspective on the Reciprocity Theorem of Classical Electrodynamics

We provide a simple physical proof of the reciprocity theorem of classical electrodynamics in the general case of material media that contain linearly polarizable as well as linearly magnetizable substances. The excitation source is taken to be a point-dipole, either electric or magnetic, and the monitored field at the observation point can be electric or magnetic, regardless of the nature of the source dipole. The electric and magnetic susceptibility tensors of the material system may vary from point to point in space, but they cannot be functions of time. In the case of spatially non-dispersive media, the only other constraint on the local susceptibility tensors is that they be symmetric at each and every point. The proof is readily extended to media that exhibit spatial dispersion: For reciprocity to hold, the electric susceptibility tensor Chi_E_mn that relates the complex-valued magnitude of the electric dipole at location r_m to the strength of the electric field at r_n must be the transpose of Chi_E_nm. Similarly, the necessary and sufficient condition for the magnetic susceptibility tensor is Chi_M_mn = Chi^T_M_nm.Comment: 15 pages, 2 figures, 28 equations, 21 reference

Shape reconstruction from shading using linear approximation

Shape from shading (SFS) deals with the recovery of 3D shape from a single monocular image. This problem was formally introduced by Horn in the early 1970s. Since then it has received considerable attention, and several efforts have been made to improve the shape recovery. In this thesis, we present a fast SFS algorithm, which is a purely local method and is highly parallelizable. In our approach, we first use the discrete approximations for surface gradients, p and q, using finite differences, then linearize the reflectance function in depth, Z ( x , y), instead of p and q. This method is simple and efficient, and yields better results for images with central illumination or low-angle illumination. Furthermore, our method is more general, and can be applied to either Lambertian surfaces or specular surfaces. The algorithm has been tested on several synthetic and real images of both Lambertian and specular surfaces, and good results have been obtained. However, our method assumes that the input image contains only single object with uniform albedo values, which is commonly assumed in most SFS methods. Our algorithm performs poorly on images with nonuniform albedo values and produces incorrect shape for images containing objects with scale ambiguity, because those images violate the basic assumptions made by our SFS method. Therefore, we extended our method for images with nonuniform albedo values. We first estimate the albedo values for each pixel, and segment the scene into regions with uniform albedo values. Then we adjust the intensity value for each pixel by dividing the corresponding albedo value before applying our linear shape from shading method. This way our modified method is able to deal with nonuniform albedo values. When multiple objects differing only in scale are present in a scene, there may be points with the same surface orientation but different depth values. No existing SFS methods can solve this kind of ambiguity directly. We also present a new approach to deal with images containing multiple objects with scale ambiguity. A depth estimate is derived from patches using a minimum downhill approach and re-aligned based on the background information to get the correct depth map. Experimental results are presented for several synthetic and real images. Finally, this thesis also investigates the problem of the discrete approximation under perspective projection. The straightforward finite difference approximation for surface gradients used under orthographic projection is no longer applicable here. because the image position components are in fact functions of the depth. In this thesis, we provide a direct solution for the discrete approximation under perspective projection. The surface gradient is derived mathematically by relating the depth value of the surface point with the depth value of the corresponding image point. We also demonstrate how we can apply the new discrete approximation to a more complicated and realistic reflectance model for SFS problem

Paleomagnetism and Rock Magnetism of Upper Jurassic Limestone and Basalt from Site 367

Remanent magnetization measurements were made on 49 samples of upper Jurassic limestone varying in color from gray to red and 7 samples of basalt recovered at Site 367. The gray limestones have very weak magnetizations and are of limited use paleomagnetically. The red limestones have stronger remanences and fair to good magnetic stabilities. The mean remanent inclination of the most reliable set of red limestone samples (N=l4) after 200-oe AF demagnetization is 25°±5.1°, near the present axial dipole field inclination (24°) as well as the expected inclination of the Jurassic field (21° to 30°) at the core site. A single stable reversed direction of magnetization (Sample 33-3, 88 cm) may represent the earliest interval of reversed geomagnetic field polarity of the late Jurassic-early Cretaceous magnetic reversal sequence. The basalt samples had very unstable remanent magnetic properties, characterized by median demagnetizing fields less than 100 oe. The samples were able to acquire large viscous remanences (VRM) in the laboratory in a 1.0-oe field. Moreover, the intensity of VRM acquired in the presence of the NRM was at least a factor of five greater than that acquired under similar conditions but after AF demagnetization. The measured magnetic properties of these basalt samples suggest that the magnetic quiet zone in the general region of Site 367 may be due in part to reduction of magnetization contrast in the magnetized basement layer by viscous remagnetization

Modulation of the slow/common gating of CLC channels by intracellular cadmium.

Members of the CLC family of Cl(-) channels and transporters are homodimeric integral membrane proteins. Two gating mechanisms control the opening and closing of Cl(-) channels in this family: fast gating, which regulates opening and closing of the individual pores in each subunit, and slow (or common) gating, which simultaneously controls gating of both subunits. Here, we found that intracellularly applied Cd(2+) reduces the current of CLC-0 because of its inhibition on the slow gating. We identified CLC-0 residues C229 and H231, located at the intracellular end of the transmembrane domain near the dimer interface, as the Cd(2+)-coordinating residues. The inhibition of the current of CLC-0 by Cd(2+) was greatly enhanced by mutation of I225W and V490W at the dimer interface. Biochemical experiments revealed that formation of a disulfide bond within this Cd(2+)-binding site is also affected by mutation of I225W and V490W, indicating that these two mutations alter the structure of the Cd(2+)-binding site. Kinetic studies showed that Cd(2+) inhibition appears to be state dependent, suggesting that structural rearrangements may occur in the CLC dimer interface during Cd(2+) modulation. Mutations of I290 and I556 of CLC-1, which correspond to I225 and V490 of CLC-0, respectively, have been shown previously to cause malfunction of CLC-1 Cl(-) channel by altering the common gating. Our experimental results suggest that mutations of the corresponding residues in CLC-0 change the subunit interaction and alter the slow gating of CLC-0. The effect of these mutations on modulations of slow gating of CLC channels by intracellular Cd(2+) likely depends on their alteration of subunit interactions

Order-free Learning Alleviating Exposure Bias in Multi-label Classification

Multi-label classification (MLC) assigns multiple labels to each sample. Prior studies show that MLC can be transformed to a sequence prediction problem with a recurrent neural network (RNN) decoder to model the label dependency. However, training a RNN decoder requires a predefined order of labels, which is not directly available in the MLC specification. Besides, RNN thus trained tends to overfit the label combinations in the training set and have difficulty generating unseen label sequences. In this paper, we propose a new framework for MLC which does not rely on a predefined label order and thus alleviates exposure bias. The experimental results on three multi-label classification benchmark datasets show that our method outperforms competitive baselines by a large margin. We also find the proposed approach has a higher probability of generating label combinations not seen during training than the baseline models. The result shows that the proposed approach has better generalization capability

A Study of the Establishment of the Evaluation Index System for Tourist Attraction Disaster Resilience

Tourism industry is highly depended on the natural environment and climate. Compared to other industries, it is more susceptible to environment and climate. Taiwan belongs to a sea island country and located in the subtropical monsoon zone. The events of climate variability, frequency of typhoons and rainfalls raged are caused regularly serious disaster. In traditional disaster assessment, it usually focuses on the disaster damage and risk assessment, which is short of the features from different industries to understand the impact of the restoring force in post-disaster resilience and the main factors that constitute resilience. The object of this study is based on disaster recovery experience of tourism area and to understand the main factors affecting the tourist area of disaster resilience. The combinations of literature review and interviews with experts are prepared an early indicator system of the disaster resilience. Then, it is screened through a Fuzzy Delphi Method and Analytic Network Process for weight analysis. Finally, this study will establish the tourism disaster resilience evaluation index system considering the Taiwan's tourism industry characteristics. We hope that be able to enhance disaster resilience after tourist areas and increases the sustainability of industrial development. It is expected to provide government departments the tourism industry as the future owner of the assets in extreme climates responses