The effectiveness of the local potential approximation in the Wegner-Houghton renormalization group

The non-perturbative Wegner-Houghton renormalization group is analyzed by the local potential approximation in O(N) scalar theories in d-dimensions $(3\leq d\leq 4)$. The leading critical exponents \nu are calculated in order to investigate the effectiveness of the local potential approximation by comparing them with the other non-perturbative methods. We show analytically that the local potential approximation gives the exact exponents up to $O(\epsilon )$ in \epsilon-expansion and the leading in 1/N-expansion. We claim that this approximation offers fairly accurate results in the whole range of the parameter space of N and d. It is a great advantage of our method that no diverging expansions appear in the procedure.Comment: 13 pages, latex, 6 figure

Wilson Renormalization Group Equations for the Critical Dynamics of Chiral Symmetry

The critical dynamics of the chiral symmetry breaking induced by gauge interaction is examined in the Wilson renormalization group framework in comparison with the Schwinger-Dyson approach. We derive the beta functions for the four-fermi couplings in the sharp cutoff renormalzation group scheme, from which the critical couplings and the anomalous dimensions of the fermion composite operators near criticality are immediately obtained. It is also shown that the beta functions lead to the same critical behavior found by solving the so-called ladder Schwinger-Dyson equation, if we restrict the radiative corrections to a certain limited type.Comment: 13 pages, 7 epsf figure

Rapidly Converging Truncation Scheme of the Exact Renormalization Group

The truncation scheme dependence of the exact renormalization group equations is investigated for scalar field theories in three dimensions. The exponents are numerically estimated to the next-to-leading order of the derivative expansion. It is found that the convergence property in various truncations in the number of powers of the fields is remarkably improved if the expansion is made around the minimum of the effective potential. It is also shown that this truncation scheme is suitable for evaluation of infrared effective potentials. The physical interpretation of this improvement is discussed by considering O(N) symmetric scalar theories in the large-N limit.Comment: 17 pages including 13 figures, LaTeX, to appear in Prog. Theor. Phys., references adde

非摂動くりこみ群による場の理論の解析

取得学位：博士(理学)，学位授与番号：博甲第237号，学位授与年月日：平成10年3月25日,学位授与年：199

Carbon ion radiotherapy for basal cell adenocarcinoma of the head and neck: preliminary report of six cases and review of the literature

<p>Abstract</p> <p>Background</p> <p>Basal cell adenocarcinoma accounts for approximately 1.6% of all salivary gland neoplasms. In this report, we describe our experiences of treatment for BCAC with carbon ion radiotherapy in our institution.</p> <p>Methods</p> <p>Case records of 6 patients with diagnosis of basal cell adenocarcinoma of the head and neck, who were treated by carbon ion radiotherapy with 64.0 GyE/16 fractions in our institution, were retrospectively reviewed.</p> <p>Results</p> <p>In a mean follow-up period of 32.1 months (14.0-51.3 months), overall survival and local control rates of 100% were achieved. Only one grade 4 (CTCAE v3.0) late complication occurred. There was no other grade 3 or higher toxicity.</p> <p>Conclusions</p> <p>Carbon ion radiotherapy should be considered as an appropriate curative approach for treatment of basal cell adenocarcinoma in certain cases, particularly in cases of unresectable disease and postoperative gross residual or recurrent disease.</p

Mobility Enhancement for IEEE 802.15.4 SUN-OFDM Using Channel Estimation and Viterbi Decoder With Likelihood Ratio Adjustment Methods

Wireless smart utility network (Wi-SUN) is one of the wireless communication technologies that realize the Internet of things (IoT). The existing Wi-SUN adopts frequency shift keying compliant with IEEE 802.15.4 for smart utility networks, also known as SUN-FSK, as its physical layer. However, owing to the increased demand for Wi-SUN applications, higher-performance communication methods even in severe fading environments with mobility are required. Orthogonal frequency-division multiplexing compliant with IEEE 802.15.4 is expected to be the most promising candidate for this. Studies on receiving methods have been conducted to accommodate high environment mobility. However, the maximum moving speed of the device is 200 km&#x002F;h if diversity reception is adopted. In this study, we proposed two channel estimation methods to obtain accurate channel state information (CSI), particularly in a frequency selective fading environment with high mobility using the coherent and linear method. Further, we also proposed a Viterbi decoder with a likelihood ratio adjusted for CSI. Using the proposed channel estimation method and decoder, the required packet error rate of 10&#x0025; is achieved at a maximum moving speed of 216 km&#x002F;h by computer simulation. If a two-branch maximum ratio combining antenna diversity is used, the PER is achieved at 720 km&#x002F;h