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The technique of sentinel lymph node (SLN) mapping in patients with colorectal cancer varies between reports, and the optimal method has not been established. The purpose of this study was to determine the optimal injection technique for SLN mapping. Sixty-nine consecutive patients who underwent curative surgery for colorectal cancer were enrolled. The SLNs was identified intraoperatively by subserosal blue dye injection (in vivo) or by submucosal injection after standard colectomy (ex vivo). If negative by conventional hematoxylin and eosin staining analysis, all lymph nodes, SLNs and non-SLNs, were subjected to further analysis by multi-level section and immunohistochemical examination. The in vivo and ex vivo injected groups were similar in demographic character, tumor size, and histological grade. The mean number of SLNs identified was 2.3 in the in vivo group and 2.6 in the ex vivo group ( p = 0.192). The detection rate of SLNs by blue dye injection was somewhat higher in the ex vivo group than in the in vivo group: 90.6 vs. 81.1% ( p = 0.219). The false-negative rate was 23.5% for the in vivo group and 13.3% for the ex vivo group ( p = 0.392). The upstaging rate, which was 18.5% overall, was similar in both groups ( p = 0.538). These findings suggest that ex vivo blue dye injection is an effective alternative to in vivo injection for identifying SLNs in patients with colorectal cancer. Because of its simplicity and applicability in routine clinical settings, further investigation of the ex vivo mapping technique is warranted. [ABSTRACT FROM AUTHOR]

An extended work on DGS modulator, which was presented before on Microwave and Optical Technology Letters Society, shall be adaptive performance and practical implementation and measurement. A DGS modulator is motivated from three benefits that can be obtained from defected ground structure; an extensive resonance, size reduction, and excellent stopband characteristic. An extensive resonance via a microstrip ground plane configuration, which includes a varactor diode bridging microstrip transmission line with variable capacitance provision that can be controlled, gives on/off switching and its attenuation level (OOK is a 100%, and which less than 100% can be ASK) that plays the key role of the ASK and OOK modulation process. A varactor diode is under control of a micro control unit that can be controlled by user interface software; therefore, user can monitor communication states while each operational sequence of a varactor diode can be controlled. Sharper phase and more precise data modulation can be achieved after several tuning works and practical trials. A modulation index (about 90–93%) with stable tag responses over the target bands (860–960 MHz, centered 912 MHz) was verified through the practical measurements on the RFID reader communication using ASK. And when a modulation index was nearly 99% (∼98.8%), this is considered to be an OOK. Overall radio communications are with EPC class-1 Gen2 Type-B and Type-C passive tags, respectively. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2646–2651, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23780 [ABSTRACT FROM AUTHOR]

This article represents a microchip balun for UHF mobile RFID system at 910 MHz. This balun is designed by transforming coupled transmission lines into lumped-element equivalent circuit, and thus monolithic elements that are fabricated by IPD technology replace it for entirely miniaturized size. The corresponding balun performs under 3 dB return loss, with nearly 176 (176.42) degree of phase difference characteristic; therefore, this meets the UHF mobile RFID reader system consideration. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2203–2206, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23617 [ABSTRACT FROM AUTHOR]

Radio characteristic evaluations of each component through the entire communication system can be performed by using the signal sampling methods, which give information of the precise statistics and high qualified specifications. Particular modern trends on electrical devices demand extremely miniaturized dimensions to meet the hand-held system units, such as personal communication services, mobile RFID applications and other possible products including crucial factors of low-profile and mobility. It is eventually aimed to avoid unnecessary waste of manufacturing products, and guarantee the mobility, ease of use and so forth. Thus the multi-mode electrical devices providing numerical advances in a single structure are needed and this is the motivation of further experiments. In this study, we propose a novel dual directional coupler design schemes including derivative calculations and its completely manufactured prototype. It has been designed by promoting three parallel coupled transmission lines with novel mathematic formula and auxiliary simulation systems. Outstanding technical features can be high isolation and directivity characteristics and these will be illustrated within the statistical tables and graphics for verification. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 775–780, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23188 [ABSTRACT FROM AUTHOR]

In this article, an amplitude shift keying (ASK) modulator with defected ground structure (DGS) is proposed for UHF radio frequency identification (RFID) system. Proposed variable DGS resonator with a varactor diode will be able to adjust the resonance frequency to achieve the ASK modulation. The variable resonance characteristics can be obtained by controlling capacitance of varactor diode, placed on the defected ground. To clarify corresponding method, we manufactured RFID system board using variable DGS resonator and measured the corresponding performance. As almost 93% of extracted data from modulation index characteristic is satisfied with both EPC class-1 Gen2 Type-B and Type-C standard protocols, we obtained stable tag response of RFID system. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2513–2516, 2007; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.22760 [ABSTRACT FROM AUTHOR]

Wide-ranging costs of laparoscopic surgery (LAP) are associated with variations in the experience levels of surgeons. There is no available report on the changes of economic outcomes relative to the LAP learning curve in the treatment of colorectal cancer. In the present study, we have compared changes in economic outcomes according to the LAP learning curve with the economic outcomes of open surgery (OS) for rectosigmoid cancer. A total of 197 patients with rectosigmoid cancer were included in this analysis; 116 received LAP and 81 received OS. Scatter of operative times demonstrated an early learning period of 37 cases in LAP. The following outcomes were compared between LAP and OS during the early learning period and experienced periods; operating room (OR) costs, OR-related hospital profit, total hospital charge, and patient payment. During the median interval of two periods according to the laparoscopic surgery learning curve, there was an inflation rate of about 10% on the medical charges such as operation, radiology, laboratory, and admission fee. Operating room costs were significantly higher after LAP during the two periods, but the median difference between LAP and OS decreased during the experienced period ($3,055 to $1,850). With increasing operative experience in LAP, the OR-related hospital deficit improved (−$1,072 to−$840). Total hospital charges were significantly higher for LAP than for OS in the early learning period ( p < 0.05), but they were similar in the experienced period ($7,983/patient versus $7,045/patient, p > 0.05). During the experienced period, patients paid a lower surcharge for LAP ($1,885–$1,118). Total hospital charges for laparoscopic surgery were substantially higher than those of open surgery during the early learning period, but become similar during the experienced period. The shortening of the learning period is a critical factor for achieving cost-effective laparoscopic surgery. [ABSTRACT FROM AUTHOR]

In order to offer RFID services on mobile phones, the RFID reader must be embedded on the handset as a chip. However, the directional coupler was used as a ceramic passive component in conventional handsets. RFID system using an identical Tx/Rx carrier frequency has a significant volume limitation compared with active components. This article presents the directional coupler design for UHF RFID mobile reader using IPD (Integrated Passive Device) process. T and π-type coupler with dimensions of 1.74 × 1.6 and 1.32 × 1.4 mm2 were assembled. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1501–1504, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22497 [ABSTRACT FROM AUTHOR]

A novel compact microstrip patch antenna is proposed for quad band, GSM850, GSM900, GPS (L1–1575 and L2–1227), and UMTS-2110 application for cellular telephone system. Design is particularly unique since it supports the new generation mobile phone where multiband operation with minimum size is greatly desired. Two microstrip line feeds placed in orthogonal directions are used for the excitation of the proposed antenna. Microstrip patch has been meandered to lengthen the electrical paths and to achieve quad frequency bands. Detail of design criteria with respect to physical parameters is described. Radiation Patterns and impedance bandwidths are measured and shown. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 997–1001, 2007; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22341 [ABSTRACT FROM AUTHOR]

In this paper, a DPDT (Double-Pole Double-Throw) switch with defected ground structure (DGS) is newly proposed for transceiver systems. A biased varactor diode is introduced to control the on/off operation of the proposed switch. In order to confirm the validity of the switch, we design and implement the switch at the 2.45-GHz frequency. It is designed specifically for antenna-diversity switching for WLAN applications. The experimental results show very low insertion loss, excellent power handling, and high isolation performances. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1127–1130, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21561 [ABSTRACT FROM AUTHOR]

This article presents a TX leakage cancellation scheme for UHF RFID readers. A prototype is implemented on a UHF RFID reader board, which includes a circulator, directional coupler, microcontrol unit (MCU)-controlled variable attenuator, and phase shifter. The difference between a conventional TX leakage canceller and this new one is that, reflected signals caused by mismatches between the front-end and the antenna are included; in addition, high isolation is supplemented at variable frequencies. About 10% of the frequency range is recovered by the best suited parameter values that provide a predetermined process of MCU; and thus, peak isolation characteristics are constantly guaranteed at each center frequency by phase-shifted signal generation that follows references stored in MCU. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2043–2045, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23592 [ABSTRACT FROM AUTHOR]