Narrow-band System Research Articles

Vascular Density of Peritoneal Endometriosis Using Narrow-Band Imaging System and Vascular Analysis Software

A pilot study was designed to analyze the vascular density of peritoneal endometriosis in 3 groups of lesions (red, black, and white) in 23 patients with peritoneal endometriosis who underwent laparoscopic surgery using the narrow-band imaging system and vascular analysis software. In the peritoneum, 21 red lesions were present in 10 patients, 12 black lesions were present in 9 patients, 12 white lesions were present in 8 patients, and 2 types of lesion were concomitantly present in 4 patients. Median vascular density of red, black, and white lesions under conventional light was 60.3%, 62.3%, and 60.6%, respectively, and under narrow-band light was 64.4%, 61.5%, and 62.0%, respectively, showing no significant differences among the lesions under either conventional or narrow-band light (p = .71 and p = .84, respectively). The median difference in vascular density under narrow-band and conventional light was not significantly different in black lesions (0.8%) or white lesions (1.0%); however, a difference of 4.5% was noted for red lesions (p <.001). We conclude that red lesions are indicative of early-stage endometriosis with angiogenesis. Use of the narrow-band system and vascular analysis software can enable accurate, objective, and reproducible evaluation of vascular density.

Physical limits to the capacity of wide-band gaussian MIMO channels

In this letter a physical limit to the information capacity of a multiple-input multiple-output (MIMO) Gaussian channel is presented exploiting the theory of non-redundant sampling of scattered fields. For a MIMO narrow-band system of arbitrarily large spatial extension, the information capacity limit is the same as the one of a single-input single-output (SISO) ultra-wide band (UWB) system. For MIMO systems of finite size, transmitting over a range of frequencies, space and frequency diversities can be optimally combined by allocating the signal power uniformly across space, and increasing linearly across frequency.

Wavelet-based spectral shaping of UWB radio signal for multisystem coexistence

Although Ultra Wide Band (UWB) wireless systems supposed to coexist with other spectrally overlapping (narrowband) wireless systems, mutual interference degrades the performance of both systems. In this paper we investigate two techniques for reducing this mutual interference which do not require modification of the narrowband system. We propose to shape the spectrum of the Transmitted Reference (TR)-UWB signal using wavelet based multi-resolution technique to avoid its interference to other wireless systems. The reverse (narrowband) interference is alleviated using a notch filter at UWB receiver that could have much smaller bandwidth in this Gaussian pulse-shaped multi-resolution environment. TR simulations under AWGN and multipath channel conditions show that up to 55 dB reduction of UWB RF energy is possible at the interfering IEEE 802.11a band using the wavelet spectral shaping technique. The challenge is not to exceed the specified pulse duration while shaping the spectrum. The proposed technique does not reduce the throughput of the UWB system. It is general in the sense, it can be used for the better coexistence of any narrowband wireless system with UWB system.

Adaptive lifting based image compression scheme for narrow band transmission system

To enable wireless internet and other data services using mobile appliances, there is a critical need to support content rich cellular data communication, including voice, text, image and video. However mobile communication of multimedia content has several bottlenecks including limited bandwidth of cellular networks, channel noise and battery constraints of the appliances. In this paper an efficient adaptive data codec for still images that can significantly minimize the energy required for wireless image communication in a narrowband system while meeting bandwidth constraints of wireless network, image quality and latency constrains of the wireless services is presented. Based on wavelet image compression an efficient wavelet Image compression algorithm (AEWICNBTS) for lossless compression of still images, enabling significant reduction in computation as well as communication energy needed with minimal degradation of image quality is proposed additionally, the wavelet image compression parameter that can be used to effect trade offs between the energy savings, quality of image and required communication bandwidth is identified. A dynamic configuration methodology that selects the optimal set of parameters to minimize energy under network service, appliance constrains is also presented. Key words: Image compression, adaptive, lifting, narrow band, transmission system.

Prevalence of Small Bowel Polyps in Patients with Familial Adenomatous Polyposis Using the Single-Balloon Enteroscope

Background: Duodenal and periampullary cancer are major cause of death in patients with familial adenomatous polyposis (FAP) after colectomy. The endoscopic study of the duodenal or periampullary lesions is easily performed with forward or side-viewing endoscopy. However, the endoscopic evaluation of polyps located distal to the duodenum is limited. The Single-Balloon enteroscopy (SBE) that allows therapeutic endoscopy, in association to the narrow-band imaging system (NBI) became a good tool to evaluate the small bowel in such patients with FAP.

Simple, all-optical, noncontact, depth-selective, narrowband surface acoustic wave measurement system for evaluating the Rayleigh velocity of small samples or areas

In this paper a new ultrasonic testing system is described that utilizes noncontact optical methods to generate and detect surface acoustic waves (SAWs) and has significant applications in the nondestructive evaluation of surface material. A narrowband SAW is generated with a new and straightforward grating mask image projection method that provides fast switching and a controllable frequency band, and hence control of the penetration depth of the ultrasonic wave. A narrowband SAW with center frequency above 30 MHz, and hence better depth resolution, is generated. The detection of the SAW is performed with a simplified design of an optical fiber interferometer that has good sensitivity and manoeuvrability without requiring additional auxiliary components. The novel combination of these two optical techniques permits the measurement of small samples that are otherwise difficult to measure, especially nondestructively. A model was constructed to simulate the temporal characteristics of the generated narrowband SAW and showed good agreement with experiment. Measurements on an aluminum sample and an extracted human incisor demonstrate the system's performance.

Narrow-band imaging system with magnifying endoscopy in differentiating colorectai neoplasms from non-neoplasms

Objective To observe the meshed capillary pattern （CP） on the surface of colorectal lesions by narrow-band imaging system with magnifying endoscopy （NBI-ME）, and to distinguish neoplasm from non-neoplasm by the change of capillary patterns. Methods A total of 144 eolorectal lesions in 102 patients detected by conventional eolonoscopy were evaluated by NBI-ME to observe the CP on surface, and by staining magnifying colonoscopy to observe the pit pattern. Results All lesions were resected endoscopically （129/144） or by surgery （15/144）, and the pathological evaluation diagnosed 30 cases of non-neoplasm （including 20 cases of hyperproliferative polyps and 10 of inflammatory polyps） and 114 cases of neoplasm （including 95 cases of adenoma and 19 cases of adenocarcinoma）. The diagnostic accuracy rate, sensitivity and specificity of conventional colonoscopy were 75.7% , 85. 1% and 40. 0% , respectively, which were significantly lower than those of NBI-ME and staining magnifying colonoscopy （ P 〈 0. 005 ） , while there was no significant difference between NBI-ME and staining magnifying colonoscopy. The CP of type Ⅰ , Ⅱ , Ⅳand Ⅵa were totally correspondent with pit pattern of type Ⅰ , Ⅱ , ⅣandⅤ1 Conclusion NBI-ME findings of colorectal lesions correlated with those of staining magnifying colonoscopy. These two techniques are both helpful in differentiating colorectal neoplasms from non-neoplasms. Key words: Colorectal neoplasm ; Endoscopy ; Narrow-band imaging system ; Magnifying endoscopy; Pit pattern

Magnifying endoscopic observation of primary follicular lymphoma of the duodenum by using the narrow-band imaging system

Magnifying endoscopic observation of primary follicular lymphoma of the duodenum by using the narrow-band imaging system

Esophageal sebaceous glands diagnosed after endoscopic mucosal resection

A 57-year-old man without any symptoms or signs of illness underwent upper-GI endoscopy for a routine health evaluation. Esophagoscopy revealed a small hiatal hernia and multiple 0.5-mm to 5-mm diameter yellow-whitish granular nodules scattered throughout the middle and lower esophagus, resembling xanthomata (A). These lesions stained slightly with Lugol iodine solution, and enhanced-magnification endoscopy with narrow-band image system revealed that they were encircled by slightly stretched microvessels (B). When autofluorescence image system was used, the intervening esophageal mucosa was green, whereas the granular lesions were pink or violet (C). To obtain sufficient tissue for a histopathologic diagnosis, we performed EMR with a ligating device (EMRL). We successfully resected the lesion without any complications. His clinical course after EMRL was uneventful and he was discharged. Histology revealed the lesions to be esophageal ectopic sebaceous glands without hair follicle (D, H&E, orig. mag. 20). The glands consisted of units of large polyhedral cells with clear vacuolated cytoplasm, accompanied by an excretory duct.

Quantitative characterization of vapour adsorption on solid surfaces and estimation of emissivity of solids using narrow-band short-wave infrared thermography

Advantages of the short-wave (2.5–3 µm) narrow-band infrared thermography are represented. The process of adsorption of water-vapour molecules on uneven surfaces of solid materials (fabrics) at room temperature is registered by the FPA-based infrared camera fulfilling the above-mentioned requirements. The pronounced “thermal flame” (“thermal fire”) phenomenon developing on the specimens' surfaces is exhibited and quantitatively represented. This thermal effect ranged within an order of magnitude. 3-µm-wavelength emissivities of different fabrics are obtained experimentally with the presented non-standard reflection-based method that needs for a narrow-band infrared system. An analytical relationship between the amount of adsorbate and the measurable excess of adsorbent temperature is derived. It is shown that the FPA-based infrared thermography makes it possible to control an incipient molecular film of 1/300-monolayer effective thickness precipitated on the exposed surface of a bulky material and of 1/600-monolayer thickness in the case of the adsorption on a thin-film adsorbent (with a double-faced surface).

Narrow-band imaging system with magnifying endoscopy for rectal amyloidosis

Infiltration of the colonic mucosa with amyloid may result in a clinical picture masquerading colorectal neoplasia.1 Narrow-band imaging (NBI) is a new technique that uses optical filters to enhance the mucosal morphology without the need for dye spraying. When used with high-resolution endoscopy (HRE), it enables endoscopic differentiation between neoplastic and nonneoplastic lesions.2 It is uncertain whether such advance in technology is useful in distinguishing GI amyloidosis from neoplastic disease.

A Novel One-Step Chromoendoscopic Method Using An Aceticacid-Indigocarmine Mixture (AIM) for the Diagnostic Accuracy in Delineating the Margin of Early Gastric Cancers

Background: Recent advances in endoscopic imaging technology have enabled the visualization of early-stage cancer and its precursors in the gastrointestinal tract. Magnifying endoscopy, high-resolution endoscopy, narrow-band imaging system, auto fluorescence imaging system, and various combinations of these technologies are all important for the recognition of small and unclear lesions. However, these technologies are not commonly used and require special equipment. Recently, we have introduced a simple chromoendoscopic method employing an acetic acid-indigo carmine mixture (AIM) for diagnosis of early gastric cancers (EGC).

Cognitive Radio Transmission Based on Direct Sequence MC-CDMA

In this paper, we propose a cognitive cellular system based on DS MC-CDMA to coexist with a number of narrow-band legacy systems in the same frequency range. If the bandwidth and the frequency location of each narrow-band system are known to this cognitive MC-CDMA, it is possible to mitigate their interfering effect in the cognitive receivers by adaptive transmission. We will develop an algorithm for calculating the adaptive transmission parameters and show that it combats interference in the channel effectively.

Achieving High-Capacity Narrowband Cellular Systems by Means of Multicell Multiuser Detection

Narrowband cellular systems require no bandwidth expansion for spectrum sharing. This attractive property is offset by the need to separate cochannel cells in order to reduce mutual interference. The net effect is a larger cluster size and a smaller system capacity than can be obtained by wideband cellular systems that operate with a cluster size of one. We propose to use a joint maximum-likelihood detection in the uplink of a narrowband system as a method to also allow it to operate with a unit cluster size. Unlike previous research, we jointly perform the detection on the desired and other-cell users. The focus of this multicell multiuser detection is more on cluster-size reduction than additional same-cell users, although the latter is also achieved. We address the problem of computational complexity by including only the strongest interferers in the joint detection. We have shown that, with a small computational cost, a narrowband system can operate with a cluster size of one and, thereby, obtain many times the spatial reuse efficiency of conventional narrowband systems.

Teletraffic Analysis of an Overlaid System Using CDMA and TDMA With Cell Coverage Area Restriction

Wireless communication has emerged as the most promising and one of the leading sectors of the telecommunications industry in the 21st century. To appreciate the expansion of the wireless sector, in 1990, there were only ten million cellular phone subscribers worldwide that frequently use first-generation technology. Today, there are more than one billion subscribers, and it is expected to increase to more than three billion subscribers during 2007-2010. Attempting to more efficiently use the limited frequency bands available for mobile communications, the idea of overlaying a code-division multiple-access (CDMA) system on an existing narrowband system has been proposed and explored. The basic idea of a CDMA overlay is to allow wideband CDMA waveforms to share a common spectrum with narrowband conventional waveforms to take advantage of the unexploited bandwidth available in the narrowband systems. Theoretically, the separation of CDMA and narrowband waveforms can be accomplished through notch filters. However, the filtering techniques are not sufficient for eliminating the multicross interference problem. In this paper, as a means of reducing the interference that cannot be eliminated by the use of filters, we have introduced a new proposal of an overlaid system in which we reduce the coverage area of the time-division multiple-access (TDMA) interference slots (slots inside the CDMA bandwidth are henceforth cited as cochannel slots). With this new strategy, we significantly reduce the effect of TDMA interference over the CDMA system.

Mobile GPS carrier phase tracking using a novel intelligent dual‐loop receiver

AbstractCarrier phase information is necessary for accurate measurements in global positioning system (GPS) applications. This paper presents a novel intelligent GPS carrier tracking loop with variable‐bandwidth characteristics for fast acquisition and better tracking capability in the presence of dynamic environments. Our dual‐loop receiver is composed of a frequency‐locked loop‐assisted phase‐locked loop structure, the fuzzy controllers (FCs), and the ATAN discriminator functions. The soft‐computing FCs provide the time‐varying loop gains to perform accurate and reliable control of the dual‐loop paradigm. Once the phase dynamic errors become large under kinematic conditions, the fuzzy loop gains increase adaptively and achieve rapid acquisition. On the other hand, when the tracking errors approach zero in the steady state, the loop gains decrease and the corresponding dual‐loop receiver returns to a narrowband system. Four types of carrier phase signals, i.e. phase offset, decaying sinusoidal phase jitter, frequency offset, and frequency ramp offset, are considered to emulate realistic mobile circumstances. Simulation results show that our proposed receiver does achieve a superior performance over conventional tracking loops in terms of faster settling time and wider acquisition range while preventing the occurrence of cycle slips. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Mathematical Formulations of Signal Propagation in Ultra-Wideband Transceiver Systems under a UWB Channel Environment with an Extension of Frequency Offset Correction

This paper analyzes mathematically the crucial aspects of signal processing in a Multi-Band (MB) Orthogonal Frequency Division Multiplexing (OFDM) based system considering Ultra-Wideband (UWB) channel environment. In the process of analysis, it emphasizes the significant features of UWB receiver design in comparison with ‘conventional’ narrow-band system. The analysis shows that the high dispersive nature of a frequency selective UWB channel effects the design of different signal processing blocks like pre-select filter, low noise amplifier (LNA) and analog-to-digital (A/D) converter in the receiver front end. The characteristic functions of each of these stages are now dominated by the channel characteristics and it needs to be modified accordingly. This analysis is extended further with the study of frequency offset error and its correction. The unbiased Cramer Rao Lower Bound (CRLB) of estimation error is calculated and supported by computer simulation. The performance of an MB-OFDM system with frequency offset correction in terms of Bit-Error-Rate (BER) is also reported.

Comparative study of conventional colonoscopy and pan-colonic narrow-band imaging system in the detection of neoplastic colonic polyps: a randomized, controlled trial

Detection and removal of adenomas by colonoscopy is an important means for preventing cancer; however, small adenomas may be missed during colonoscopy. The narrow-band imaging (NBI) system clearly enhances the microvasculature in neoplastic lesions, making it appear as a dark complex. Therefore, the NBI system may improve the detection of colonic neoplasias. However, no randomized, controlled trials have evaluated the efficacy of a pan-colonic NBI system in adenoma detection. We conducted a randomized, controlled trial to determine the efficacy of the pancolonic NBI system in adenoma detection. Two hundred forty-three patients were randomized, 121 to conventional colonoscopy and 122 to pan-colonic NBI system. Demographics, indication for colonoscopy, and quality of preparation were similar between groups. Extubation time was not significantly different between the conventional colonoscopy and pan-colonic NBI system. The proportions of patients with at least one adenoma and those with multiple adenomas were not significantly different between groups. However, the pan-colonic NBI system significantly increased the total number of adenomas detected (P < 0.05) and the number of diminutive (<5 mm) adenomas detected (P < 0.05). The pan-colonic NBI system allowed detection of more diminutive adenomas in the distal colon than did conventional colonoscopy (P < 0.01), and more patients in the NBI group had at least one diminutive adenoma than in the control group (P < 0.05). The pan-colonic NBI system improves the total number of adenomas detected, including significantly more diminutive adenomas, without prolongation of extubation time. These results indicate that routine use of the NBI system for surveillance of diminutive adenomas may be recommended.

Discrete Time-Frequency Characterizations of Dispersive Linear Time-Varying Systems

A class of linear time-varying systems can be characterized by dispersive signal transformations, such as nonlinear shifts in the phase of the propagating signal, causing different frequencies to be shifted in time by different amounts. In this paper, we propose a discrete time-frequency model to decompose the dispersive system output into discrete dispersive frequency shifts and generalized time shifts, weighted by a smoothed and sampled version of the dispersive spreading function. The discretization formulation is obtained from the discrete narrowband system model through a unitary warping relation between the narrowband and dispersive spreading functions. This warping relation depends on the nonlinear phase transformations induced by the dispersive system. In order to demonstrate the effectiveness of the proposed discrete characterization, we investigate acoustic transmission over shallow water environments that suffers from severe degradations as a result of modal frequency dispersions and multipath fading. Using numerical results, we demonstrate that the discrete dispersive model can lead to a joint multipath-dispersion diversity that we achieve by properly designing the transmitted waveform and the reception scheme to match the dispersive environment characteristics

High Contrast Imaging Improves the Visualization and Detection of Gastrointestinal Vascular Ectasias

Introduction: Vascular Ectasia (VE) of the gastrointestinal tract are a common cause of gastrointestinal bleeding, but can be difficult to detect during endoscopy due to factors including blood pressure, blood volume, hydration and drugs such as meperidine. The opiate antagonist, naloxone has been used to unmask otherwise unseen VE. New endoscopic imaging techniques have been developed to produce high contrast images (HCI) with the aim of enhancing the visualization of early neoplastic lesions. These may have additional value in detecting VE at endoscopy. Methods: We used the high contrast settings on endoscopes to visualize VE in patients undergoing elective endoscopy for recent gastrointestinal bleeding. The Fujinon EPX-4400 multi- band system was used in 4 patients; it produces an image using electronically selected wavelengths from blue, green and red components of light reflected from the mucosa. The system has 10 built in settings of which preset 4 (blue light at 405 nm, green light at 500 nm, red light at 520 nm) was used as it displays blood vessels as dark purple- black structures that contrast strongly against a brighter mucosa. We also used the Olympus narrow band system in one patient, which provides an image with a bluish hue, but at fixed wavelengths. VE were sought on forward advancement of the endoscope, to minimize trauma and suction artifacts. The imaging modes in both systems were switched between standard endoscopy and HCI in each field of view prior to advancing to the next area. Results: In 2 EGDs, 8 VE were seen with standard endoscopy, but 15 were found with HCI. In 3 colonoscopies, 3 VE were seen with standard endoscopy, but 8 were found with HCI. The VE that were visible under white light endoscopy became far more prominent under HCI. Overall, HCI revealed 4.4 ± 1.3 VE per procedure, and standard endoscopy 2.2 ± 1.0 VE per procedure; (p = 0.01). Conclusions: These early findings indicate the potential utility of high contrast imaging for the detection of VE in the gastrointestinal tract. The images are composed using reflected light with wavelengths that are well absorbed by hemoglobin in blood vessels, which are thus displayed as dark structures that contrast with the more reflective, brighter mucosal surface. The resulting HCI help facilitate imaging of vasculature and may unmask otherwise unseen VE.