Mitsubishi

About: Mitsubishi is a company organization based out in Tokyo, Japan. It is known for research contribution in the topics: Layer (electronics) & Signal. The organization has 53115 authors who have published 54821 publications receiving 870150 citations. The organization is also known as: Mitsubishi Group of Companies & Mitsubishi Companies.

Signal Processing With Compressive Measurements

Abstract: The recently introduced theory of compressive sensing enables the recovery of sparse or compressible signals from a small set of nonadaptive, linear measurements. If properly chosen, the number of measurements can be much smaller than the number of Nyquist-rate samples. Interestingly, it has been shown that random projections are a near-optimal measurement scheme. This has inspired the design of hardware systems that directly implement random measurement protocols. However, despite the intense focus of the community on signal recovery, many (if not most) signal processing problems do not require full signal recovery. In this paper, we take some first steps in the direction of solving inference problems-such as detection, classification, or estimation-and filtering problems using only compressive measurements and without ever reconstructing the signals involved. We provide theoretical bounds along with experimental results.

Physical aspects of a real-time tumor-tracking system for gated radiotherapy

Abstract: Purpose: To reduce uncertainty due to setup error and organ motion during radiotherapy of tumors in or near the lung, by means of real-time tumor tracking and gating of a linear accelerator Methods and Materials: The real-time tumor-tracking system consists of four sets of diagnostic X-ray television systems (two of which offer an unobstructed view of the patient at any time), an image processor unit, a gating control unit, and an image display unit The system recognizes the position of a 20-mm gold marker in the human body 30 times per second using two X-ray television systems The marker is inserted in or near the tumor using image guided implantation The linear accelerator is gated to irradiate the tumor only when the marker is within a given tolerance from its planned coordinates relative to the isocenter The accuracy of the system and the additional dose due to the diagnostic X-ray were examined in a phantom, and the geometric performance of the system was evaluated in 4 patients Results: The phantom experiment demonstrated that the geometric accuracy of the tumor-tracking system is better than 15 mm for moving targets up to a speed of 40 mm/s The dose due to the diagnostic X-ray monitoring ranged from 001% to 1% of the target dose for a 20-Gy irradiation of a chest phantom In 4 patients with lung cancer, the range of the coordinates of the tumor marker during irradiation was 25–53 mm, which would have been 96–384 mm without tracking Conclusion: We successfully implemented and applied a tumor-tracking and gating system The system significantly improves the accuracy of irradiation of targets in motion at the expense of an acceptable amount of diagnostic X-ray exposure

Robust 1-Bit Compressive Sensing via Binary Stable Embeddings of Sparse Vectors

Abstract: The compressive sensing (CS) framework aims to ease the burden on analog-to-digital converters (ADCs) by reducing the sampling rate required to acquire and stably recover sparse signals. Practical ADCs not only sample but also quantize each measurement to a finite number of bits; moreover, there is an inverse relationship between the achievable sampling rate and the bit depth. In this paper, we investigate an alternative CS approach that shifts the emphasis from the sampling rate to the number of bits per measurement. In particular, we explore the extreme case of 1-bit CS measurements, which capture just their sign. Our results come in two flavors. First, we consider ideal reconstruction from noiseless 1-bit measurements and provide a lower bound on the best achievable reconstruction error. We also demonstrate that i.i.d. random Gaussian matrices provide measurement mappings that, with overwhelming probability, achieve nearly optimal error decay. Next, we consider reconstruction robustness to measurement errors and noise and introduce the binary e-stable embedding property, which characterizes the robustness of the measurement process to sign changes. We show that the same class of matrices that provide almost optimal noiseless performance also enable such a robust mapping. On the practical side, we introduce the binary iterative hard thresholding algorithm for signal reconstruction from 1-bit measurements that offers state-of-the-art performance.

Learning gender with support faces

Abstract: Nonlinear support vector machines (SVMs) are investigated for appearance-based gender classification with low-resolution "thumbnail" faces processed from 1,755 images from the FERET (FacE REcognition Technology) face database. The performance of SVMs (3.4% error) is shown to be superior to traditional pattern classifiers (linear, quadratic, Fisher linear discriminant, nearest-neighbor) as well as more modern techniques, such as radial basis function (RBF) classifiers and large ensemble-RBF networks. Furthermore, the difference in classification performance with low-resolution "thumbnails" (21/spl times/12 pixels) and the corresponding higher-resolution images (84/spl times/48 pixels) was found to be only 1%, thus demonstrating robustness and stability with respect to scale and the degree of facial detail.

Driving Forces Enable High-Titer Anaerobic 1-Butanol Synthesis in Escherichia coli

Abstract: 1-Butanol, an important chemical feedstock and advanced biofuel, is produced by Clostridium species. Various efforts have been made to transfer the clostridial 1-butanol pathway into other microorganisms. However, in contrast to similar compounds, only limited titers of 1-butanol were attained. In this work, we constructed a modified clostridial 1-butanol pathway in Escherichia coli to provide an irreversible reaction catalyzed by trans-enoyl-coenzyme A (CoA) reductase (Ter) and created NADH and acetyl-CoA driving forces to direct the flux. We achieved high-titer (30 g/liter) and high-yield (70 to 88% of the theoretical) production of 1-butanol anaerobically, comparable to or exceeding the levels demonstrated by native producers. Without the NADH and acetyl-CoA driving forces, the Ter reaction alone only achieved about 1/10 the level of production. The engineered host platform also enables the selection of essential enzymes with better catalytic efficiency or expression by anaerobic growth rescue. These results demonstrate the importance of driving forces in the efficient production of nonnative products.