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This work presents polarization-sensitive optical coherence tomography (PS-OCT) using only linearly polarized light. The main characteristics of linear PS-OCT include the following. (1) In a turbid medium with linear birefringence, the degree of polarization (DOP) of backscattered linearly incident polarized light does not change significantly with the increase of birefringence value; (2) the phase retardation of the sample can be obtained from only the phase difference between the orthogonal polarization heterodyne signals, so a common phase noise rejection mode is introduced. These advantages may not only support the immunity of background phase noise and laser frequency noise, but also increase the sensitivity of phase retardation measurements; (3) the dynamic range of phase retardation in this system is between 0° and 180°

To include biologic factors in parallel-architecture normal-tissue complication probability (NTCP) model for radiation-induced liver disease (RILD) after three-dimensional conformal radiotherapy (3D-CRT) for gastric or hepatic cancer.A total of 151 patients (89 with hepatocellular carcinoma and 62 with gastric cancer) who received 3D-CRT to the liver were included (isocenter dose range 33.0 to 66.0 Gy; mean 48.0 Gy). RILD was defined as grade 3 or higher liver toxicity according to Common Toxicity Criteria Version 2.0 of the National Cancer Institute within 4 months after 3D-CRT. Possible correlations of patient-related or dosimetric factors with RILD were tested. Maximum-likelihood analysis estimated NTCP model parameters for group and subgroups. Goodness-of-fit analysis estimated deviance of NTCP model parameters between subgroups.RILD developed in 25 patients. Hepatitis B virus carrier status (p0.001) was the only significant independent factor. The 4 parallel NTCP model parameters, mean functional reserve (V(50)), width of functional reserve distribution (sigma), dose damage to 50% of liver subunits (D(50)), and slope parameter for subunit dose-response (k), were respectively, 0.54, 0.14, 50 Gy, 0.18 (group); 0.53, 0.07, 50 Gy, 4.6 x 10(-7) (carriers); 0.59, 0.12, 25 Gy, 59.8 (noncarriers). In carrier-state subgroups, goodness-of-fit deviance with 1 subgroup's parameter set would have been worse in the other group. Across subgroups, patients with RILD all had liver fraction damage (f) greater than 0.4 compared with wider distribution for the whole group.RILD is described with a parallel-architecture NTCP model for HBV carriers and noncarriers with a threshold effect greater than 0.4. The main difference is in slope parameter for subunit dose-response.

The photoluminescence (PL) spectrum of the ZnTe/ZnSe quantum dot (QD) structure which has a type II band alignment was investigated. A broader structure peaking at 2.180 eV together with the features of the ZnSe buffer layer located at 2.820 eV in the PL spectrum at 10 K were observed. The broadness of the PL attributes to the spatial inhomogeneity of the QD sizes. The PL spectrum was a normal distribution with a variance of 0.002 eV 2 . However, the dot size distribution was a deformed Gaussian. Using only one set of data of dot size distribution measured by the Atomic Force Microscopy (AFM), the statistical estimates with standard errors were evaluated using the bootstrap methodology. The probability distribution was inferred by calculating the means, percentiles and correlation coefficients of the base diameter and the height of the QDs. We concluded that the dot distributions were indeed a deformed Gaussian and the correlation coefficient of the diameter and the height of the QDs was 0.49 ± 0.01. The uniformity of the dot size distribution was poor. To infer the dot size distribution from the PL spectrum, we numerically solved the Schrodinger equation by elaborating on the orthogonal periodic functions (OPF) approximation for the type II lens shaped QDs. The convergence of the probability density was discussed in a great detail. We found that the band edge discontinuities inside the dot acts as a barrier with ΔE c = 315 meV for the conduction band and as a well with ΔE v = 735 meV for the valence band. In the AFM measurement, the offset in dot height is 14 A and the aspect ratio is 0.04. We employed the Schrodinger equation to correlated the PL spectrum (intensity versus optical energy) to the AFM data (number of QDs versus dot size) and the agreement was excellent.

Purpose: To identify the factors associated with radiation-induced liver disease (RILD) and to describe the difference in normal tissue complication probability (NTCP) between subgroups of hepatocellular carcinoma patients undergoing three-dimensional conformal radiotherapy (3D-CRT). Methods and Materials: A total of 89 hepatocellular carcinoma patients who completed 3D-CRT for local hepatic tumors were included. The average isocenter dose was 49.9 ± 6.2 Gy. Logistic regression analysis was used for the association between statistically significant factors and RILD (defined as Grade 3 or 4 hepatic toxicity of elevated transaminases or alkaline phosphatase within 4 months of completing 3D-CRT) in multivariate analysis. Maximal likelihood analysis was conducted to obtain the best estimates of the NTCP model parameters. Results: Of the 89 patients, 17 developed RILD. In univariate analysis, hepatitis B virus (HBV)-positive status and the mean radiation dose to the liver were the two factors significantly associated with the development of RILD. Of the 65 patients who were HBV carriers, 16 had RILD compared with 1 of 24 non–carrier patients ( p = 0.03). The mean radiation dose to liver was significantly greater in patients with RILD (22.9 vs. 19.0 Gy, p = 0.05). On multivariate analysis, HBV carrier status (odds ratio, 9.26; p = 0.04) and Child-Pugh B cirrhosis of the liver (odds ratio, 3.65; p = 0.04) remained statistically significant. The best estimates of the NTCP parameters were n=0.35, m=0.39, and TD 50 (1) = 49.4 Gy. The n, m, TD 50 (1) specifically estimated from the HBV carriers was 0.26, 0.40, and 50.0 Gy, respectively, compared with 0.86, 0.31, and 46.1 Gy, respectively, for non–carrier patients. Conclusion: Hepatocellular carcinoma patients who were HBV carriers or had Child-Pugh B cirrhosis presented with a statistically significantly greater susceptibility to RILD after 3D-CRT.

Multiphoton generated autofluorescence and second harmonic signals are useful luminescent signatures for probing the structural and spectral properties of collagen fibers. However, optimization of image formation deep within a three-dimensional collagen sample may be hindered by index-mismatch induced spherical aberration. In this work, we examined this issue by comparing the axial multiphoton luminescence profiles of bovine tendon under water, glycerin, and oil immersion conditions. Our results show that, although in general, oil immersion imaging resulted in the slowest decay of measured axial luminescence profile, other immersion conditions can perform better at specific locations within the tendon, indicating the existence of local variations of refractive indices within the collagen-filled tendon. Our results suggest that optimizing multiphoton imaging of collagen requires acquiring and comparing imaging results using different immersion fluids and that the results may be used to infer the spatial distribution of refractive indices in biological specimens.

The photoreflectance spectra of an undoped InGaP film grown on a GaAs (001) substrate by gas-source molecular beam epitaxy have been measured at the temperature of 70 K. The band-gap optical transitions attributed to the InGaP epilayer and GaAs substrate have been characterized. Two broad features, which originate from the interface of the InGaP and GaAs layer, also appeared with the transition energies of 1.523 eV and 1.877 eV in the photoreflectance spectra. In addition, the amplitudes of these two optical features show different trends with increasing power of an extra DC pumping laser. The results suggest that the two unusual optical features are attributed to the spatial indirect transitions at the interface.

Adult respiratory distress syndrome (ARDS) has been the major cause of mortality in burn injury. The authors reported the experience of using extracorporeal membrane oxygenation (ECMO) to treat adult burn patient with ARDS. Three patients with burn or electric injury, around 48.9% of body surface area over second-degree burns, developed ARDS after resuscitation. All had positive blood culture and depended on a ventilator more than 5 days before ECMO. Venovenous (VV) ECMO was started at the beginning of severe respiratory failure with an oxygen index of 61.6 +/- 15.5 cm H2O/mm Hg (or =40 cm H2O/mm Hg), partial arterial oxygen tension to inspired oxygen fraction (Pa(O2)/Fi(O2)) of 46.1 +/- 7.0 mm Hg (or =200 mm Hg), positive end expiratory pressure (PEEP) of 15.7 +/- 1.6 cm H2O (or =10 cm H2O), alveolar-arterial difference in oxygen concentration (A-a D(O2)) of 618.9 +/- 19.3 mm Hg (or =300 mm Hg), and lung compliance of 17.3 +/- 4.6 ml/cm H2O (or =30 ml/cm H2O). The VV type had to be converted to the newly designed veno-venoarterial (V-VA) ECMO due to the myocardial dysfunction. Two of three patients survived. The duration of ECMO was 160.2 +/- 51.1 h. Two patients received debridement of escar during ECMO support and desmopressin infusion, and no increased bleeding or coagulopathy was found. The respiratory parameters were significantly improved after ECMO, especially in the survivors. ECMO is also suitable for ARDS in adult burn injury.

The Taita No. 1 ventricular assist device (T-VAD) is a totally implantable pulsatile impeller centrifugal pump driven by a magnetically suspended motor. The flow can achieve 2.01 +/- 0.17 L/min against a pressure of 100 mm Hg under 0.266 +/- 0.017 amp and 13.55 +/- 0.41 voltage. The speed was around 3,500 rpm. It consumed less than 6 W of power, resulting in less heat production and mechanical bearing complications. The impeller vane was designed to have both radial and axial curves according to the stream surface and stream lines to reduce thrombosis and hemolysis. Eight calves weighing 80 to 100 kg (mean 87 +/- 12 kg) were used for experiments. With the calves under general anesthesia, left posterolateral thoracotomy was performed to connect the inflow tube with the atrial appendage and to anastomose the outflow tube with the descending aorta. The calves usually awoke and stood up within hours after discontinuation of anesthetics. The mean survival of the calves was 75 +/- 42 days (range 33-148 days). The terminations of experiments were mainly due to infection. During the course of pumping, no significant deterioration of liver or renal function was noted. The evaluation of serum samples from the implanted calves indicated that hemolysis was not associated with use of the T-VAD. The average daily free hemoglobin level was 8.08 +/- 3.05 mg/dl, which was less than the set limit of 20 mg/dl. The red blood cell and platelet count and hemoglobin of implanted animals were within the normal range. In our results, the T-VAD provided competent pulsatile function without severe blood damage or organ dysfunction.

The purpose of this study was to determine the physiologic relationship between the cardiac cycle and the nonpulsatile impeller centrifugal Taita No.1 left ventricular assist device (T-LVAD) in a chronic animal study. The relationship of the cardiac cycle, pump flow, aortic pressure, left ventricle pressure, and pump power were analyzed by 5 phases in 4 stages. The isovolumetric ventricular phase is from mitral valve closure (MVC) to aortic valve opening (AVO) and is called Stage 1. The ejection phase is from AVO to aortic valve closure (AVC) and is called Stage 2. The isovolumetric relaxation phase is from AVC to MVC and is called Stage 3. The passive filling and atrial contraction phase is from MVC to mitral valve opening (MVO) and called Stage 4. Based on evidence from the physiologic volume change of the left ventricle, the change of pump flow of the T-LVAD in a cardiac cycle by variable voltages of pump control was evaluated using animal models. After left posteriolateral thoracotomy via the fifth intercostal space under general anesthesia, the nonpulsatile centrifugal T-LVAD was implanted into 2 healthy calves. The inflow of the T-LVAD was inserted into the left ventricle through the mitral valve via the left atrial appendage. The arterial blood pressure waveform was measured and recorded on the outflow of the T-LVAD. The 4 phases of a cardiac cycle were defined as MVC-AVO (Stage 1), AVO-AVC (Stage 2), AVC-MVO (Stage 3) and MVC-MVO (Stage 4) according to the outflow pressure of the outflow of the T-LVAD and differential pressure between the outflow and inflow of the T-LVAD. We carried out the real-time waveform measurement for electrocardiogram, the outflow pressure, the T-LVAD flow and the speed, as well as open loop and constant voltage (V). In a cardiac cycle, the sensing current of the T-LVAD was inverse to the speed. The flow of the T-LVAD at the 4 stages was measured individually and analyzed with different control voltages from 10 to 18 V. The highest flow ratio of MVC-AVC/AVC-MVC was noted when the T-LVAD worked on 14 V. By using analysis methodology of the flow ratio of a cardiac cycle, the optimal physiologically effective control of the T-LVAD might be achieved.

Information on volume-pressure relationships of human lungs is usually based on indirect determination of intrapleural pressure (P(ip)) obtained from the esophagus. Unfortunately, cardiac beat artifact frequently corrupts measurement of esophageal pressure (P(es)). In this study, we presented a modified adaptive noise cancellation (MANC) scheme for removing the cardiac beat artifact in the P(es) signal. The proposed methodology used an airflow signal as the reference signal with least-mean-square method as the adaptive algorithm. The results of six experiments on two Brown-Norway rats showed a significant reduction of the apparent cardiac pulsation with minimal distortion of the P(es) signal. The MANC filter also showed evidence of peak suppression at integer multiples of heart rate in the fast Fourier transform of the P(es) signal while leaving the remaining spectrum largely unperturbed. A t-test method and the ratio of standard deviation to mean (std/mean) statistics of airway resistance (R(aw)) values were used to evaluate the performance of the MANC filter. In all six experiments, a reduction of std/mean of R(aw) by 12.5%-68% was obtained, indicating the effectiveness of the proposed scheme.

The method of truncated singular value decomposition (SVD) is proposed for electrocardiogram (ECG) data compression. The signal decomposition capability of SVD is exploited to extract the significant feature components of the ECG by decomposing the ECG into a set of basic patterns with associated scaling factors. The signal informations are mostly concentrated within a certain number of singular values with related singular vectors due to the strong interbeat correlation among ECG cycles. Therefore, only the relevant parts of the singular triplets need to be retained as the compressed data for retrieving the original signals. The insignificant overhead can be truncated to eliminate the redundancy of ECG data compression. The Massachusetts Institute of Technology-Beth Israel Hospital arrhythmia database was applied to evaluate the compression performance and recoverability in the retrieved ECG signals. The approximate achievement was presented with an average data rate of 143.2 b/s with a relatively low reconstructed error. These results showed that truncated SVD method can provide an efficient coding with high-compression ratios. The computational efficiency of the SVD method in comparing with other techniques demonstrated the method as an effective technique for ECG data storage or signals transmission. Index Terms-Data compression, electrocardiogram, feature extraction, quasi-periodic signal, singular value decomposition.

A simple digitizer with utilizes a piece of touch panel position sensor (TPPS) material and a homemade control board has been developed for semi-automatic quantitative morphometry. The profile areas were digitized by tracing with a freehand drawing and the raw data were then stored in a personal computer (PC) for further processing. This is an extremely useful tool for digitizing and converting graphic data from previously published data for comparison and/or processing of new physical parameters. Sequential architecture of hardware and software components for control and data acquisition are described and discussed in this paper. The resolution and accuracy of this PC-based digitizer are also characterized and discussed.

Electrolyte electroreflectance has been used to determine the interband transition energy and the defects inside HgCdTe. The reflectivity is a good gauge for observing surface properties. This techniqu is coupled with electrochemical etching to study the characteristics of this material. From a reflectivity experiment we compared the difference between HCl and lactic acid etching

In this experiment, the centrifugal Taita No.1 left ventricular-assist device was implanted in a calf. The blood pump was driven by constant voltage with the open-loop control method. The pump inflow flow and pump outflow pressure were recorded and analyzed synchronously. According to the status of aortic valve and mitral valve, the cardiac cycle was divided into four stages. The flow in each stage was calculated and an optimal pump control index was obtained. The index suggests an optimal applied voltage of the pump for reducing suction and backflow effects.

The integrated EMG (IEMG) is the most widely used method to estimate the degree of muscular activity. However, the results of any given method of quantification are limited to the relation between 5 or 6 different discrete force levels and IEMG or other quantified electromyography (EMG). Moreover, the shape, the accuracy and the repoducibility of these relationships are inconsistent. Therefore, we propose a novel spectrum probability frequency (SPF) algorithm which can estimate the muscle force in a continuous manner and also design two principles to achieve significant improvements in the quality of EMG quantification. It is concluded that our method allows an accurate estimation of quadriceps muscle force, even when high noisy EMG data are used.

As a major component of the connective tissues, collagen fibers are responsible for various physiological functions inside the body. They provide support for the skin, partial focusing through the cornea, and coordinate movements via tendons, ligaments, and cartilages. In many medical procedures, thermal reorganization of the collagen structure is inevitable or desired. Therefore, the optimization of the therapeutic values of these procedures requires the characterization of thermal changes to collagen fibers. In this presentation, we use multiphoton microscopy to achieve this task. We will show that second harmonic generation (SHG) microscopy can characterize the thermally altered states of collagen and that they have potentials to be used in imaging applications in vivo.

Atherosclerosis is unquestionably the leading cause of morbidity and mortality in developed countries. In the mean time, the worldwide importance of acute vascular syndromes is increasing. Because collagen fiber is a critical component of atherosclerotic lesions; it constitutes up to 60% of the total atherosclerotic plaque protein. The uncontrolled collagen accumulation leads to arterial stenosis, whereas excessive collagen breakdown weakens plaques thereby making them prone to rupture finally. Thus, in this study, we present the first application, to our knowledge, of using polarization-sensitive optical coherence tomography (PS-OCT) in human atherosclerosis. We demonstrate this technique for imaging of intensity, birefringence, and fast-axis orientation simultaneously in atherosclerotic plaques. This in vitro study suggests that the birefringence change in plaque is due to the prominent deposition of collagen according to the correlation of PS-OCT images with histological counterpart. Moreover, we can acquire quantitative criteria based on the change of polarization of incident beam to estimate whether the collagen synthesized is "too much" or "not enough". Thus by combining of high resolution intensity imaging and birefringence detection makes PS-OCT could be a potentially powerful tool for early assessment of atherosclerosis appearance and the prediction of plaque rupture in clinic.

Continuous arterial blood pressure monitoring is essential in monitoring patients during surgical operation or in intensive care units. In this study, we propose a new method to estimate beat-to-beat systolic blood pressure by combining the pulse arrive time and normalized pulse width measurement. The method was examined in nine patients who were in ICU. Results shows the new method has higher linearity (0.8218) and better precision (3.0775) than the methods using either pulse arrive time or pulse width only.

We report a method for extracting the birefringence properties of samples with a novel proposed polarization-sensitive optical coherence tomography (PS-OCT) using linearly polarized incident light.

The thermal disruption of collagen I in rat tail tendon is investigated with second-harmonic generation (SHG) microscopy. We investigate its effects on SHG images and intensity in the temperature range 25 degrees-60 degrees C. We find that the SHG signal decreases rapidly starting at 45 degrees C. However, SHG imaging reveals that breakage of collagen fibers is not evident until 57 degrees C and worsens with increasing temperature. At 57 degrees C, structures of both molten and fibrous collagen exist, and the disruption of collagen appears to be complete at 60 degrees C. Our results suggest that, in addition to intensity measurement, SHG imaging is necessary for monitoring details of thermally induced changes in collagen structures in biomedical applications.

Optical coherence tomography (OCT) is analogous to ultrasound imaging except that it uses infrared light instead of sound. Polarization-sensitive optical coherence tomography (PS-OCT) combines the advantages of OCT and provides additional image contrast of the tested sample. We demonstrate this technique for imaging of back-reflected light, birefringence, and fast-axis orientation simultaneously in different kinds of atherosclerosis plaque. This in vitro study suggests birefringence changes in plaque are due to the prominent deposition of collagen or cholesterol by correlating PS-OCT images with histology. Thus the combination of high resolution structural imaging and birefringence detection make PS-OCT a potentially powerful tool for early assessment of atherosclerosis appearance and prediction of plaque rupture.

A novel laser Doppler flowmetry scheme is reported that adjusts the processing bandwidth adaptively to optimise the estimation of flow. To obtain an adequate processing bandwidth, the Doppler spectra is first fitted to the Lorentzian function, and the bandwidth at half the maximum of the Lorentzian function is used as an indicator of the major frequency range of the signal. The processing bandwidth is then tuned accordingly, and a frequency-weighted algorithm is applied to compute the fluid velocity. To investigate the influence of the processing bandwidth, an in vitro experiment was performed. In the experiment, the flow rate was controlled at constant velocity in the range from 0 to 18.52 mm s(-1), and the fluid velocity indices were calculated using adaptive and fixed processing bandwidths, respectively. The results showed that the adaptive processing bandwidth adjustment, not only significantly reduced the biological zero (9.6% of the case using 100 kHz bandwidth), but also enhanced the sensitivity of the laser Doppler measurement (over 20%) and linearly responded to a wider velocity range (R2 = 0.979 for velocity from 0 to 18.52 mm s(-1)).

We studied the photoreflectance (PR) and photoluminescence (PL) spectroscopies of self-assembled InAs quantum dots grown on n+-GaAs (100) by molecular beam epitaxy. The PL spectroscopy of self-assembled Ge quantum dots (Ge-QDs) grown on n+-Si (100) by metal organic chemical vapor deposition epitaxy was also investigated. PL spectra show the optical transitions from the ground state and excited states in the InAs quantum dots (InAs-QDs) and a transition from the ground state in the Ge-QDs at the temperature 20 K. PR spectra show the energy features of the transitions of the ground state and four excited states in the InAs-QDs, InAs wetting layer, and GaAs band-gap. The fitted results of the transition energies and the broadening parameters are reported. The results demonstrate that low growth rate of the InAs-QDs, the submonolayer deposited of the alternating beam, and covered with the overgrowth InGaAs methods, have improved the nano-structure quality of the InAs-QD, grown at 485¦C and V/III ratio of 2. The high quality Ge-QDs were made, and characterized by PL experiments.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The measurement of esophageal pressure (Pes) is a simple technique that can be used to calculate the lung mechanical parameters. In clinical practice the traditional strategy for cardiac beat artifact minimization in Pes measurement is to adjust either the position of esophageal balloon or the posture of the body under test. The authors propose a new scheme combining a modified adaptive noise cancellation (MANC) method and an adaptive FIR (AFIR) filter to eliminate the cardiac beat artifact from Pes measurement. In experiments, the authors also find that the harmonic effect interferes with the measurement of Pes. In using the MANC the authors do not have to carefully adjust the position of the esophageal balloon to avoid the results being affected by body posture, and it is independent of frequency variations of cardiac beat and respiration. In using the AFIR it is found to be suitable for most cases that the frequency of the cardiac beat is different from the respiration frequency but not suitable for the frequencies or harmonics that overlap slightly.

An automatic spike detection algorithm for classification of multi-channel EEG signals based on artificial neural network is presented. Radial basis function (RBF) neural network was chosen for single channel recognition, with model optimization using receiver operating characteristics analysis. Waveform simplification was employed for high noise immunity. Feature extraction with as few as three parameters was used as preparation for the inputs to the neural network. Identification of multi-channel geometric correlation was performed to further lower the false-positive rate by using an incidence matrix. Threshold value for spike classification was chosen for simultaneous maximization of detection sensitivity and selectivity. Evaluation with visual analysis in this preliminary study showed a 83% sensitivity using 16-channel continuous EEG records of four patients, while a high false positive rate was found, which was believed to arise from the extensive and exhaustive visual analysis process. The computation time required for spike detection was significantly less than that needed for online display of the signals on the monitor. We believe that the algorithm proposed in this study is robust and that the simple structure of RBF neural network yields high potential for real-time implementation.

Endoscopy is a versatile medical device, but with deficiency of severe image distortion from a super-wide angle lens CCD- camera installed. We designed a planar circular pattern target mounted on a XYZ transnational stage and developed a calibration method to correct the distorted image. Through the image shaping similarity and symmetric properties of a circular pad posing in the specific spatial coordinates, an optimized algorithm is to adjust the orientation of the gastroscopic head and the coordinates of the target until the accurate system alignment obtained. The profiles of image mapping and the calibration object are to derive both the image distortion and calibration function as single variable polynomial equations. Using the calibration function, the distorted gastroscopic image could transfer to comply with an ideal pinhole mapping. The experimental results validated that a gastroscopic image could be corrected and depict better geometrical information. Concurrently displaying with the traditional screen, this technique could aid the physician in metering a tumor or lesion size.

A graphic user interface and real-time laser Doppler velocimeter (LDV) based on the digital signal processor (DSP) had been designed and developed. The hardware setup included the Michelson inteferrrometer optics, photo-detector, current to voltage converter, AC amplifer and filtering circuits, as well as a DSP module. The software system on the Dsp module was also developed to access data and to perform the moment weighting algorithms. In addition, the processed data was transmitted to the personal computer and advanced analysis could be achieved. The velocity measurement using developed LDV device was calibrated by a mirror mounted on a linear vibrator. The outcomes presented high linearity and good accuracy. In vitro experiment employing this LDV system was also carried out. The results showed that the developed LDV instrument offered a flexible tool to investigate the blood flow of microcirculation system.

Oesophageal pressure (Pes) measurements are important in medical research and useful in clinical diagnosis. Measurements, however, are contaminated heavily by cardiac artifacts. The spectrum and waveform of the Pes signal is obtained from the oesophageal balloon. Adaptive finite impulse response (AFIR) filter and modified adaptive noise cancellation (MANC) methods are adopted to filter out cardiac beat interference. These results are compared. In the frequency domain, frequency variations and spectral overlap between the Pes components and cardiac beat signal components impact on the performance of the filter. From our experimental results on power strength, the fourth or higher harmonics did not have any significant effect on the filter performance. However, the second harmonics of these signals had a significant effect on the filtering result. Thus, in the design of AFIR filters, attention is needed to minimise these effects. In frequency analysis, these harmonics or overlapping frequencies do not affect MANC. MANC was the better method for eliminating cardiac beat artifact in Pes measurement. The dynamic compliance (Cdyn) was also used to evaluate the performance of MANC and AFIR. The standard deviation of Cdyn was less than 0.15 using MANC, compared with standard deviations as high as 0.57 for AFIR. We conclude that MANC performs better than AFIR.

Temperature dependence photoreflectance has been used to study InAs/GaAs self-assembled quantum dots (QDs). The QDs samples were grown on (100) misoriented 7 degrees toward (110) GaAs semi-insulting substrate by a gas source molecular beam epitaxy with changing V/III ratio. The energy features of PR spectra from QDs and wetting layer (WL) were fitted by the first derivative Gaussian functional form and band-gap feature was fitted by the derivative-like Lorentian line shape function.THE blue-shift of optical transition energies responded from QDs has been characterized. The signals responded from an ultra-thin wetting layer of InAs/GaAs QDs samples and band-gap transition energy from GaAs portions were also observed. It demonstrates that the energy features of PR spectrum responded form QDs and WL section could provide the important information about QDs quality. The results show that the size, uniformity and density of QDs can be improved by the changing V/III ratio.

A new electronic system has been developed to trace the location and movement of small animals in an open-field environment. The system, incorporated with a conventional touch panel position sensor (TPPS) and an IBM AT compatible computer, automatically digitizes and records the moving path of the animal. The detection principle of the TPPS is based on the pressure effect. Whenever an animal is put on the TPPS, the location of the animal can be detected. The personal computer system is in corporate to record the locomotion data of the animal. The system described here is shown to be a reliable and accurate tool to record the moving path of an animal. This measurement did not require extra light or other stimuli, and the apparatus is low priced, and simple to build up and user friendly.

Two GaAs/AlGaAs passive semiconductor channel waveguides of the multiple quantum well structure have been made by molecular beam epitaxial growth technique. The specimens were studied by photoreflectance (PR) spectroscopy at room temperature. The micro-structures of the PR spectral energy features on the layers of the multiple quantum wells and band edge transition were observed. The optical transition energy features were fitted by the first derivative Gaussian function form (GFF) and the peak positions of the theoretical prediction for the micro-structures were calculated by using effective mass envelope function model. The energy features of the micro-structure in PR spectra were identified and interpreted. The results show that PR is a powerful tool to characterize the optical waveguides of multiple quantum well structure.

The electrolyte electroreflectance and reflectivity measurements were used to study the etching process and analyze the etching mechanism of etched anodic oxide film on HgCdTe. The observed shift of the energy peak in reflectance spectrum can be explained by the surface roughness. It was found that the oxide etched by HCl or HNO3 does not recover the original reflectivity spectra due to the surface characteristics, but lactic acid does. The multiple reflection theory was used to calculate the thickness and the etching rate of the oxide film. The etching characteristics of lactic acid have also been studied for different concentrations.

of Electrical EngineeringTaipei, Taiwan, Republic of ChinaFeng-Yuh Juang, Tin-Fung Chang and Jia-Song WuChung-Shan Institute of Science and TechnologyLung-Tan, Taiwan, Republic of ChinaABSTRACTElectrolyte electroreflectance (EER) is used to investigate the near surface properties of HgCdTe. Weused the technique of EER coupled with electrochemical etching to study the characteristics of HgCdTe.Annealing of B ion-implanted HgCdTe with ZnS encapsulation and anode sulfide film is studied. Theresults of fitting parameters show that a highly disordered surface layer exists after implantation, and anobvious recovery occurs after the sample is annealed at 2000 C It also shows that there are no obviousimprovements when the sample is annealed at 3000 C. The sample encapped with CdS film is better thanuncapped CdS film. We found that the composition of Cd at the surface changes due to the chemicalinteraction of anode sulfide film. It also shows that the sulfide active CdS film can improve the adherenceof ZnS to the MCT substrate and make the sample more stable.

The excitonic photoreflectance (PR) spectra of GaAs/A1GaAs multiple quantum wells, grown by the molecular beam epitaxial (MBE) technique, were investigated at oblique and near-normal incident angle with different polarized probe lights. The PR spectra have been measured at room temperature using He-Ne laser as a pumping beam in order to study the variations of the spectral line shapes. The experimental results show that the usefulness of the electromodulation to characterize the microstructure of the substrate may be enhanced if we take in account the polarization state of the probe light which is incident at larger oblique angle. The PR spectra were fitted by a third order derivative functional line shape, thus making it possible to determine the energy band gap, broadening parameters, amplitudes, and the phases of the spectral features precisely.

A phase retardation plate, such as a quarter-wave plate, is able to control the state of polarization. Thus, a precise simultaneous determination of phase delay between two eigen-polarization states and its fast-axis angle is essential to the performance of the phase retardation plate to control the state of polarization. Consequently, the measurement of the two-dimensional spatiotemporal distribution of phase retardation and the fast-axis angle become crucial when a large-area of phase retardation plate, such as that for a liquid crystal display, is characterized, due to the inhomogeneity of the retardation plate. In order to measure the linear birefringence parameters, phase retardation and fast-axis angle at the same time, a novel polarized optical heterodyne interferometer is developed, with which the parameters of a quarter-wave plate are successfully measured and verified. The features of this device are (1) a common-path configuration, (2) measurement independent of laser intensity, and (3) the capability of simultaneously determining the spatiotemporal distributions of phase retardation and fast-axis angle of a retardation plate.

Materials/Methods: From 1993 to 2001 a total of 151 patients (89 with hepatocellular carcinoma and 62 with gastric cancer) underwent 3DCRT to part of liver were included in this study. The isocenter dose ranged from 33.0 to 66.0Gy (mean: 48.0Gy). Dose distribution and the corresponding volumetric data were obtained from the computerized planning system. A complication (RILD) was defined as grade 3 or higher RTOG liver toxicity within 4 months after completing 3DCRT. Patient-related and dosimetric factors were tested for their correlation with RILD in univariate and multivariate analyses. A maximal likelihood analysis was used to yield the best estimates for the parallel NTCP model parameters of the whole group and the subgroups. Patients were divided by statistically significant non-dosimetric factors, which were integrated into the modeling process for better describing the occurrence of RILD. Goodness of fit analysis was used to estimate the deviance of NTCP model parameters of subgroups from the whole group.

The thermal annealing properties of B+ implantation in HgCdTe are investigated by the electrolyte electroreflectance technique. The various thermal annealing conditions, such as temperature, time, and presence or absence of ZnS encapsulated passivation, are used as parameters to study the surface properties of HgCdTe and are characterized by electrolyte electroreflectance spectroscopy. We found that Hg accumulates near the surface region of an encapsulated sample, and Hg is lost at a depth of 1600 Å. The quality of the crystal is much improved when the sample is annealed at 200°C for a duration of over 30 minutes.

For this study, a microcomputer‐controlled electrolyte electroreflec‐tance (EER) system has been set up. EER measurements are carried out on samples of Ga1‐xAlx, As alloys in the photon energy range of 1.4 to 4.2 eV at room temperature. The E0, E0+?0, E 1 and E 1 +? 1 transitions have been determined as a function of alloy composition x. The transition energies at critical points show quadratic dependence on the alloy composition, with the relation E(x)=a+bx+cx2. Based on this relation, the EER technique has been utilized to study the variations in composition across the surface of the sample. This technique is nondestructive and can readily be employed under atmospheric conditions at room temperature. This method is sensitive enough to determine the changes of composition ?x within a range of \% with a spatial resolution of 150 μm.

The establishment of the Synchrotron Radiation Research Center under the Executive Yuan was approved by the government of the Republic of China on July 9,1983. The major parts of Synchrotron Radiation Facility have been reviewed and advised by the Technical Review Committee ( TRC ) and decided by the Board of Directors (BOD) during this period. The detailed information from the TRC and BOD was presented at the ’86 X-ray microscopy conference [1]. The technical aspects of the Taiwan Synchrotron Radiation facility ( Taiwan Light Source ) and its current progress as well as the organization of the technical and user divisions of SRRC are described.

The construction of a 1.3GeV synchrotron radiation storage ring in Taiwan (Taiwan Light Source (TLS)) began recently (Yen, 1986). The photon energy (critical energy of 0.99keV) of the TLS without insertion device will cover the near infrared, visible light, ultraviolet and vacuum ultraviolet as well as soft x-ray spectra. The synchrotron storage ring, when completed, will provide useful photons for various x-ray imaging work including x-ray microscopy. In anticipation of the commission of the synchrotron, we have built a stationary target x-ray source for some initial work on x-ray contact imaging. The stationary anode x-ray source was chosen for its simplicity and reliability. The soft x-ray source had been set up by the middle of August, 1986. After the source was tested, two biological specimens were exposed to the source.