A Novel Analog Interpolation Method for Heterodyne Laser Interferometer.

Laser interferometer technology is used in the precision positioning stage as an encoder. For better resolution, laser interferometers usually work with interpolation devices. According to the interpolation factor, these devices can convert an orthogonal sinusoidal signal into several square-wave signals via digital processing. The bandwidth of the processing will be the limitation of the moving speed of the positioning stage. Therefore, the user needs to make a trade-off between the interpolation factor and the moving speed. In this investigation, a novel analog interpolation method for a heterodyne laser interferometer has been proposed. This method is based on the principle of the lock-in amplifier (LIA). By using the proposed interpolation method, the bandwidth of the laser encoder system can be independent of the interpolation factor. This will be a significant benefit for the ultra-high resolution encoder system and the laser interferometers. The concept, design, and experiment are revealed in this manuscript. The experimental results show that the proposed interpolation method can reach nanometer resolution with a heterodyne laser interferometer, and the bandwidth of the signal is independent of the resolution.

Development of the Heterodyne Laser Encoder System for the X-Y Positioning Stage.

This investigation develops a laser encoder system based on a heterodyne laser interferometer. For eliminating geometric errors, the optical structure of the proposed encoder system was carried out with the internal zero-point method. The designed structure can eliminate the geometric errors, including positioning error, straightness error, squareness error, and Abbe error of the positioning stage. The signal processing system is composed of commercial integrated circuits (ICs). The signal type of the proposed encoding system is a differential signal that is compatible with most motion control systems. The proposed encoder system is embedded in a two-dimensional positioning stage. By the experimental results of the positioning test in the measuring range of 27 mm × 27 mm, with a resolution of 15.8 nm, the maximum values of the positioning error and standard deviation are 12.64 nm and 126.4 nm, respectively, in the positioning experiments. The result shows that the proposed encoder system can fit the positioning requirements of the optoelectronic and semiconductor industries.

Linear Displacement Calibration System Integrated with a Novel Auto-Alignment Module for Optical Axes.

The quality of processed workpieces is affected directly by the precision of the linear stage. Therefore, the linear displacement calibration of machine tools must be implemented before delivery and after employment for a period of time. How to perform a precise calibration with high inspection efficiency is a critical issue in the precision mechanical engineering industry. In this study, the self-developed system integrated by the measurement module based on the common path Fabry-Pérot interferometer for linear displacement and the auto-alignment module for optical axes was proposed to realize the automatic linear displacement calibration of the linear stages. The measurement performance of the developed structure was verified experimentally. With the auto-alignment module, the cosine error was reduced to 0.36 nm and the entire procedure accomplished within 75 s without the limitation of the perceived resolution of the human eye, operational experience, and the risk of misalignment and broken cable. According to the comparison of experimental results for the linear displacement, the repeatability of the proposed measurement module was less than 0.171 µm. After the compensation procedure according to the linear displacement calibration, the systematic positional deviation, repeatability, and accuracy of the linear axis could be improved to 4 µm, 1 µm, and 5 µm respectively. Hence, the calibration efficiency can be improved by 80% with the proposed compact system, which is beneficial for the linear displacement calibration of machine tools in the precision mechanical engineering industry.

4D-CT angiography with arterial- and venous-phase anatomical pre-surgical approaches in cases with head and neck neoplasms.

PURPOSE: The relationship between neoplasm and its surrounding vascular structure is essential to the following clinical treatment plan. In this study, 4D computed tomography angiography (4D-CTA) with a wide scan range and dynamic phases of arteriography and venography was used to describe detailed anatomical information for pre-surgical approaches. MATERIALS AND METHODS: From January 2011 to February 2012, we subjected 13 patients with head and neck neoplasms to 4D-CTA. 4D-CTA was performed by a multidetector computed tomography (MDCT) scanner of 320 detectors. The parameters were set to a 0.5 mm section thickness, at 0.5 second per rotation, 80 kV and 150 mA. The scan range was set depending on the tumor size, with a maximal setting of 16 cm. A 30 mL contrast medium with 60 mL saline was injected at the rate of 5-7 mL per second based on the vascular patency, scanning every 2 seconds from the 16th to the 28th second after contrast injection. RESULTS: The vasculature surrounding the tumors was successfully illustrated in all cases. The 4D-CTA provided detailed vascular information that was compatible with the surgical and angiographic findings. CONCLUSION: 4D-CTA with a wide scan range and precise injection timing methods facilitated an anatomical approach to tumor-related vascular structures, providing detailed vascular information. This non-invasive technique may be useful for evaluating neoplasms and developing treatment plans, as an alternative to conventional angiography.

Use of XPS to Quantify Thickness of Coatings on Nanoparticles.

XPS and other surface sensitive methods are being increasingly used to extract quantitative information about organic and inorganic coatings and contamination on nanoparticles. The extraction of coating thickness requires information about particle diameter from other measurements, such as electron microscopy, combined with a model that includes the physical processes associated with XPS. Advantages of using XPS include the sensitivity to very thin coatings (or surface contamination) and the ability to extract important information about organic layers. Single particle information from electron microsocpy combined with XPS sensitivity in determining composition make a powerful combination for nanoparticle anlaysis.

Heart Rate Variability Predicts Neurogenic Pulmonary Edema in Patients with Subarachnoid Hemorrhage.

BACKGROUND: An alternation of sympathetic and vagal nervous activity has been suggested to be one possible mechanism of neurogenic pulmonary edema (NPE) in patients with subarachnoid hemorrhage (SAH). The study aimed to explore if sympathovagal modulation assessed by frequency domains of heart rate variability (HRV) is associated with impending NPE in patients with SAH. METHODS: Two hundred forty-eight consecutive spontaneous SAH adult patients were included in this single-center cohort study. A continuous 10-min electrocardiography for HRV analysis was recorded. The patients were stratified into NPE and non-NPE based on serially clinical and radiologic findings within 24 h. Seven frequency domains of HRV were compared between these 2 groups. RESULTS: Compared to the non-NPE (n = 212), the NPE (n = 36) had significantly higher mean arterial pressure, higher World Federation of Neurological Surgeons (WFNS) class, higher Hunt-Hess scale, lower total power (TP), lower very low-frequency component, lower low-frequency component, lower normalized low-frequency component (LF %), higher normalized high-frequency component, and lower low-frequency component/high-frequency component ratio. Multiple logistic regression model identified WFNS class (OR 4.048; 95 % CI 1.589-10.311), LF % (OR 0.933; 95 % CI 0.910-0.958), and TP (OR 0.995; 95 % CI 0.992-0.998) as the significant variables associated with occurrence of NPE. The area under receiver operating characteristic curves of LF % and TP were found to be 0.838 (95 % CI 0.774-0.901) and 0.653 (95 % CI 0.557-0.749), respectively. CONCLUSION: Loss of cardiac variability and depressed sympathovagal modulation, represented by TP and LF %, may predict the development of NPE in the early stage in patients with SAH.

ECG abnormalities predict neurogenic pulmonary edema in patients with subarachnoid hemorrhage.

OBJECTIVE: The study aims to assess if electrocardiographic (ECG) abnormalities could predict the development of neurogenic pulmonary edema (NPE) within 24 hours in cases of spontaneous subarachnoid hemorrhage (SAH). METHODS: We studied prospectively a cohort of 269 adult patients with nontraumatic SAH in an emergency department of a university-affiliated medical center. A 12-lead ECG was taken for these patients. The patients were stratified into NPE and non-NPE based on serially clinical and radiologic findings. The ECG abnormalities were compared between these 2 groups of patients. RESULTS: Compared with the non-NPE (n = 229), the NPE (n = 40) had significantly higher World Federation of Neurological Surgeons class (P < .001), higher Hunt-Hess scale (P < .001), and higher prevalence of diabetes mellitus (P = .033). In addition, the percentage of ECG morphological abnormality was significantly higher in NPE, in which nonspecific ST- or T-wave changes (NSSTTCs) are significantly higher. Multiple logistic regression model identified World Federation of Neurological Surgeons class (95% confidence interval [CI], 2.6-13.3; P < .001), abnormal Q or QS wave (95% CI, 1.1-9.1; P = .038), and NSSTTCs (95% CI, 1.2-7.5; P = .016) as the significant variables associated with NPE. CONCLUSIONS: Electrocardiographic abnormalities, especially abnormal Q or QS wave and NSSTTCs, may predict the development of NPE within 24 hours in adult patients with spontaneous SAH.

Accurate quantitative measurement of lunate uncovering ratio--is Gilula's semiquantitative test reliable?

The Gilula's test suggests the presence of ulnocarpal translation when 50% or more of the lunate lies medial to the ulnar edge of radius. The purpose of this study was to examine the reliability of this semiquantitative test as there was inconsistency between the previous publications in regarding 50% as the cutoff value for the normal lunate uncovering ratio (LUR). We utilized the Picture Archiving and Communication System to investigate radiographs of 299 normal adult wrists and emphasized defined radiographic landmarks for accurate quantitative measurement. Our mean LUR was 35%(SD8) with a range of 8 to 49%. Therefore we re-affirmed the reliability of the Gilula's test since none of our normal wrists had a LUR of 50% or greater.

Multi-interferometric displacement measurement system with variable measurement mirrors.

Laser interferometers have been widely implemented for the displacement sensing and positioning calibration of the precision mechanical industry, due to their excellent measuring features and direct traceability to the dimensional definition. Currently some kinds of modified Fabry-Perot interferometers with a planar mirror or a corner cube prism as the measurement mirror have been proposed. Each optical structure of both models has the individual particularity and performance for measuring applications. In this investigation, a multi-interferometric displacement system has been proposed whose measurement mirror can be quickly and conveniently altered with a planar mirror or a corner cube reflector depending on the measuring demand. Some experimental results and analyses about the interpolation error and displacement measurements with both reflectors have been demonstrated. According to the results, suggestions about the choice of a measuring reflector and interpolation model have been presented. With the measuring verifications, the developed system with a maximum standard deviation less than 0.2081 µm in measuring range of 300 mm would be a compact and robust tool for sensing or calibrating the linear displacement of mechanical equipment.

Modified Fabry-Perot interferometer for displacement measurement in ultra large measuring range.

Laser interferometers have demonstrated outstanding measuring performances for high precision positioning or dimensional measurements in the precision industry, especially in the length measurement. Due to the non-common-optical-path structure, appreciable measurement errors can be easily induced under ordinary measurement conditions. That will lead to the limitation and inconvenience for in situ industrial applications. To minimize the environmental and mechanical effects, a new interferometric displacement measuring system with the common-optical-path structure and the resistance to tilt-angle is proposed. With the integration of optomechatronic modules in the novel interferometric system, the resolution up to picometer order, high precision, and ultra large measuring range have been realized. For the signal stabilization of displacement measurement, an automatic gain control module has been proposed. A self-developed interpolation model has been employed for enhancing the resolution. The novel interferometer can hold the advantage of high resolution and large measuring range simultaneously. By the experimental verifications, it has been proven that the actual resolution of 2.5 nm can be achieved in the measuring range of 500 mm. According to the comparison experiments, the maximal standard deviation of the difference between the self-developed Fabry-Perot interferometer and the reference commercial Michelson interferometer is 0.146 µm in the traveling range of 500 mm. With the prominent measuring characteristics, this should be the largest dynamic measurement range of a Fabry-Perot interferometer up till now.

Influence of intensity loss in the cavity of a folded Fabry-Perot interferometer on interferometric signals.

Fabry-Perot interferometer is often used for the micro-displacement, because of its common optical path structure being insensitive to the environmental disturbances. Recently, the folded Fabry-Perot interferometer has been investigated for displacement measurements in large ranges. The advantages of a folded Fabry-Perot interferometer are insensitive to the tilt angle and higher optical resolution. But the design of the optical cavity has become more and more complicated. For this reason, the intensity loss in the cavity will be an important parameter for the distribution of the interferometric intensity. To obtain a more accurate result of such interferometer utilized for displacement measurements, the intensity loss of the cavity in the fabricated folded Fabry-Perot interferometer and the modified equation of the folded Fabry-Perot interferometer will be described. According to the theoretical and experimental results, the presented model is available for the analysis of displacement measurements by a folded Fabry-Perot interferometer.

Effects of propranolol on the left ventricular volume of normal subjects during CT coronary angiography.

OBJECTIVE: The purpose of this study is to determine the effects of propranolol on the left ventricular (LV) volume during CT coronary angiography. MATERIALS AND METHODS: The LV volume of 252 normal Chinese subjects (126 subjects with propranolol medication and 126 age- and gender-matched Chinese subjects without medication) was estimated using 64 slices multi-detector CT (MDCT). The heart rate difference was analyzed by the logistic linear regression model with variables that included gender, age, body height, body weight, systolic blood pressure (SBP), diastolic blood pressure (DBP) and the dosage of propranolol. The following global LV functional parameters were calculated: the real-end diastolic volume (EDV), the real-end systolic volume (ESV) and the real-ejection fraction (EF). RESULTS: The female subjects had a greater decrease of heart rate after taking propranolol. The difference of heart rate was negatively correlated with the dosage of propranolol. The real-EDV, the real-ESV and the real-EF ranged from 48.1 to 109 mL/m², 6.1 to 57.1 mL/m² and 41% to 88%, respectively. There was no significant difference in the SBP and DBP between the groups without and with propranolol medication (123 ± 17 and 80 ± 10 mmHg; 120 ± 14 and 80 ± 11 mmHg, respectively). The real-EDV showed no significant difference between these two groups, but the real-ESV and real-EF showed significant differences between these two groups (69.4 ± 9.3 and 70.6 ± 8.9 mL/m²; 23.5 ± 5.7 and 25.6 ± 3.7 mL/m², 66.5 ± 5.1% and 63.5 ± 4.6%, respectively). CONCLUSION: The difference of heart rate is significantly influenced by gender and the dosage of propranolol. Propranolol will also increase the ESV, which contributes to a decreased EF, while the SBP, DBP and EDV are not statistically changed.

Hepatic ADC value correlates with cirrhotic severity of patients with biliary atresia.

INTRODUCTION: At least 40% of survivors of biliary atresia have progressive cirrhosis even after undergoing Kasai operation. The values of hepatic apparent diffusion coefficient and apparent-diffusion-coefficient-related indices were applied to biliary atresia patients and correlated with cirrhotic severity scores of model for end-stage liver disease or pediatric end-stage liver disease model, Child-Turcotte, and Child-Pugh systems. MATERIALS AND METHODS: Thirty-three biliary atresia patents (mean=1140, 61-4314 days of age) received magnetic resonance image examinations due to complications of biliary atresia from April 2008 to August 2009. Two non-breath-hold diffusion weighted imaging sequences were performed with motion-probing gradients in three directions with two b values: 0/100 and 0/500 s/mm2; 1000 ms/61.1 ms, time to repeat/time to echo; number of excitation, 1.0; 8 mm section thickness; 40 cm×40 cm field of view; 128×256 matrix in all biliary atresia patients and 18 control subjects. We used the Spearman rank correlation test to analyze the relationship among the scores of model for end-stage liver disease or pediatric end-stage liver disease model, Child-Turcotte and Child-Pugh scores and right hepatic apparent diffusion coefficients, apparent diffusion coefficient using b factor of 500-albumin product and alanine transaminase/apparent diffusion coefficient with b factor of 500 ratio. RESULTS: The right hepatic apparent diffusion coefficient using b factor of 100, apparent diffusion coefficient with b factor of 500 and product of apparent diffusion coefficient with b factor of 500-albumin level were significantly negatively correlated (p≤0.0125) with model for end-stage liver disease or pediatric end-stage liver disease model, Child-Turcotte, and Child-Pugh scores of biliary atresia patients. The ratio of alanine transaminase level/right hepatic apparent diffusion coefficient with b factor of 500 was also significantly (p≤0.0251), moderately correlated with Child-Turcotte and Child-Pugh scores (rho=0.5256 and 0.7518, respectively). CONCLUSION: Right hepatic apparent diffusion coefficient with b factor of 500 and alanine transaminase/right hepatic apparent diffusion coefficient with b factor of 500 can be useful for long-term follow-up of cirrhotic severity in biliary atresia patients.

Fabry-Pérot interferometer utilized for displacement measurement in a large measuring range.

The optical configuration of a Fabry-Pérot interferometer is uncomplicated. This has already been applied in different measurement systems. For the displacement measurement with the Fabry-Pérot interferometer, the result is significantly influenced by the tilt angles of the measurement mirror in the interferometer. Hence, only for the rather small measuring range, the Fabry-Pérot interferometer is available. The goal of this investigation is to enhance the measuring range of Fabry-Pérot interferometer by compensating the tilt angles. To verify the measuring characteristic of the self-developed Fabry-Pérot interferometer, some comparison measurements with a reference standard have been performed. The maximum deviation of comparison experiments is less than 0.3 µm in the traveling range of 30 mm. The experimental results show that the Fabry-Pérot interferometer is highly stable, insensitive to environment effects, and can meet the measuring requirement of the submicrometer order.

Gender differences in carpal height ratio in a taiwanese population.

PURPOSE: To discover whether there is a significant difference in carpal height ratio (CHR) between men and women aged 20 to 50 years. METHODS: We retrospectively reviewed 261 cases of normal plain wrist radiographs and measured the CHR using the Picture Achieving and Communication System. Each case was then stratified by gender and age (20-29, 30-39, and 40-50 y). RESULTS: The mean CHR was 0.52 +/- 0.03 for men (range, 0.43-0.59), 0.50 +/- 0.03 for women (range, 0.43-0.57), and 0.51 +/- 0.03 for the total population (range, 0.43-0.59). The difference in CHR between men and women was statistically significant (p<.01). However, there was no significant difference (p=.13) among age groups in either men or women. CONCLUSIONS: We recommend using gender-specific norms (ie, 0.52 +/- 0.03 for men and 0.50 +/- 0.03 for women, respectively) for CHR. Without gender specification, a subtle abnormality may be overlooked in men, and there may be an overdiagnosis of carpal disorder in women. Further investigations are needed to look into possible racial differences, because our study is based on a homogeneous ethnic Chinese population.

The comparison of environmental effects on michelson and fabry-perot interferometers utilized for the displacement measurement.

The optical structure of general commercial interferometers, e.g., the Michelson interferometers, is based on a non-common optical path. Such interferometers suffer from environmental effects because of the different phase changes induced in different optical paths and consequently the measurement precision will be significantly influenced by tiny variations of the environmental conditions. Fabry-Perot interferometers, which feature common optical paths, are insensitive to environmental disturbances. That would be advantageous for precision displacement measurements under ordinary environmental conditions. To verify and analyze this influence, displacement measurements with the two types of interferometers, i.e., a self-fabricated Fabry-Perot interferometer and a commercial Michelson interferometer, have been performed and compared under various environmental disturbance scenarios. Under several test conditions, the self-fabricated Fabry-Perot interferometer was obviously less sensitive to environmental disturbances than a commercial Michelson interferometer. Experimental results have shown that induced errors from environmental disturbances in a Fabry-Perot interferometer are one fifth of those in a Michelson interferometer. This has proved that an interferometer with the common optical path structure will be much more independent of environmental disturbances than those with a non-common optical path structure. It would be beneficial for the solution of interferometers utilized for precision displacement measurements in ordinary measurement environments.

Picture archive and communication system (PACS) in the detection of fish bone: an animal study.

OBJECTIVES: We have developed an animal model to investigate the feasibility of using a digital radiography picture archive and communication system (PACS) to identify fish bones. SUBJECTS AND METHODS: Bones from 21 species of freshwater and seawater fish were placed in the upper esophagus of a test pig. Digital radiographic images of the lateral neck were taken (60 kV, 200 mA, and 20 ms, 100 cm in distance). The images were interpreted by three radiologists. The chi(2) test, Kendall's coefficient of concordance, and the logistic regression model were applied for statistical analyses. RESULTS: Milkfish had the lowest visibility (33.3%) in PACS. There was a significant variation in the ratings of visibility among three radiologists (P < 0.01, Kendall's coefficient 0.75). Seawater vs freshwater category, bone length, and radiologist were significant factors that affected visibility. CONCLUSION: The sensitivity is 0.89. Images from seawater fish with long bones have better visibility. PACS is feasible in diagnosing upper esophagus fish bones, but the physician's knowledge of local varieties of fish prior to image study is equally important.

Dynamic effects of axial loading on the lumbar spine during magnetic resonance imaging in patients with suspected spinal stenosis.

BACKGROUND: Previous studies have shown that axial compression in extension (ACE) of the spine during magnetic resonance imaging (MRI) has revealed unexpected pathological features compared with the conventional psoas-relaxed position (PRP) used in imaging. The purpose of this study was to evaluate the dynamic effect of axial loading on lumbar spinal stenosis using MRI in patients with spinal stenosis. METHODS: A total of 14 women and 11 men with lumbar spinal stenosis were examined in both PRP and ACE positions. We calculated the dural-sac cross-sectional area (DCSA) to evaluate severity of spinal canal stenosis. DCSA, as well as the dural-sac anteroposterior diameter (DAPD) and dural-sac transverse diameter (DTD) in both positions were measured using a digital image view station. A paired t test determined the differences in DCSA, DAPD and DTD between the two positions at each intervertebral disc level. RESULTS: Axial loading increased severity of lumbar spinal stenosis during MRI, as demonstrated by a decrease in DCSA from 20.5% to 6.3% (mean, 11.40 +/- 3.66%) between the PRP and ACE positions (p less than 0.01). Significant differences were also noted in DAPD and DTD between the PRP and ACE positions (p less than 0.01). A significant correlation was found between the decrease in mean DCSA and that in DAPD and DTD. The decrease in mean DCSA, DAPD and DTD following axial compression was greatest at the L4/5 and L5/S1 levels. CONCLUSION: Axial loading increases severity of lumbar canal stenosis and the effect of axial loading on MRI examination is greatest at the L4/5 and L5/S1 levels.