Masking Operation Research Articles

Retinal Nerve Fiber Layer Thickness Reproducibility Using Seven Different OCT Instruments

The clinical utility of new optical coherence tomography (OCT) instruments strongly depends on measurements reproducibility. The aim of this study was to assess retinal nerve fiber layer (RNFL) thickness reproducibility using six different spectral-domain OCTs (SD-OCTs) and one time-domain OCT. RNFL thickness (average and four quadrant) from six SD-OCTs (Spectral OCT/SLO OPKO/OTI, 3D-OCT 2000 Topcon, RS-3000 NIDEK, Cirrus HD-OCT Zeiss, RTVue-100 Optovue, and Spectralis Heidelberg) and one time-domain OCT (Stratus OCT Zeiss) was measured twice in 38 right eyes of 38 randomly chosen healthy volunteers by two masked operators. Inter- and intraoperator reproducibility was evaluated by the intraclass correlation coefficient (ICC), coefficient of variation (CV), and Bland-Altman test analysis. Instrument-to-instrument reproducibility was determined by ANOVA for repeated measures. We also tested how the devices disagree in terms of systemic bias and random error using a structural equation model. Mean RNFL average thickness ranged from 90.08 μm to 106.51 μm. Cirrus and Heidelberg showed the thinnest RNFL values in all measurements, Topcon the highest. ICC, CV, and Bland-Altman plots showed variable inter- and intraoperator agreement depending on the instrument. Heidelberg demonstrated the best interoperator (ICC, 0.92; CV, 1.56%) and intraoperator (ICC, 0.94 and 0.95; CV, 1.28% and 1.26%, respectively, for operator A and operator B) agreement for average RNFL thickness. Heidelberg demonstrated the higher agreement in inter- and intraoperator reproducibility, Optovue the worst. In light of our error analysis results, we found that a scale bias among instruments could interfere with a thorough RNFL monitoring, suggesting that best monitoring is obtained with the same operator and the same device.

A Novel Design Flow for Dummy Fill Using Boolean Mask Operations

Dummy fill has been demonstrated to be an effective technique to reduce process variation and improve manufacturability for advanced integrated circuit (IC) designs. However, the computation load, often several days for a realistic IC design, is a significant portion of the cycle time for delivering first silicon on new or modified designs. In this paper, we propose a novel design flow and dummy-fill algorithm based on Boolean operations, which greatly improves computational efficiency and pattern density uniformity, and enables dummy generation to be combined with the mask-preparation Boolean operations performed by the mask-fabrication facility. Mask data preparation can be performed in parallel with dummy generation and post-dummy simulation checks at the design house, resulting in improved first-silicon cycle time. Experimental results demonstrate these benefits in the context of an advanced foundry process technology.

Association between genetic risk score and periodontitis onset and progression: A pilot study

AimRecent research has focused attention on the single nucleotide polymorphisms (SNPs) involved in the host response in periodontitis. However, so as to combine the relatively small effects of individual genes the use of multi locus genetic risk (GRS) has been proposed. This study aims to evaluate whether the genetic risk score may predict periodontitis onset and progression. Materials and methodsFifty patients were divided into various groups according to periodontal status. Total DNA was isolated from epithelial oral cells by a masked operator and the selected SNPs were analysed. A GRS was calculated using an additive model. ResultsWe found a strong association only between TNF rs1800629 and diffused forms of periodontitis. Data show that GRS is able to discriminate diffused forms of periodontitis from localized ones. Finally, a progressive increase of the GRS is evident in advanced periodontitis in comparison with early forms. DiscussionIn recent years, research on genetic polymorphism has had limited success in predicting the susceptibility to periodontal disease. However, our results indicate that the use of the genetic risk score could be promising. Further studies are necessary to include data from multiple genes so as to confirm our result.

Longitudinal Change Detected by Spectral Domain Optical Coherence Tomography in the Optic Nerve Head and Peripapillary Retina in Experimental Glaucoma

To investigate whether longitudinal changes deep within the optic nerve head (ONH) are detectable by spectral domain optical coherence tomography (SDOCT) in experimental glaucoma (EG) and whether these changes are detectable at the onset of Heidelberg Retina Tomography (HRT; Heidelberg Engineering, Heidelberg, Germany)-defined surface topography depression. Longitudinal SDOCT imaging (Spectralis; Heidelberg Engineering) was performed in both eyes of nine rhesus macaques every 1 to 3 weeks. One eye of each underwent trabecular laser-induced IOP elevation. Four masked operators delineated internal limiting membrane (ILM), retinal nerve fiber layer (RNFL), Bruch's membrane/retinal pigment epithelium (BM/RPE), neural canal opening (NCO), and anterior lamina cribrosa surface (ALCS) by using custom software. Longitudinal changes were assessed and compared between the EG and control (nonlasered) eyes at the onset of HRT-detected surface depression (follow-up 1; [FU1]) and at the most recent image (follow-up 2; [FU2]). Mean IOP in EG eyes was 7.1 to 24.6 mm Hg at FU1 and 13.5 to 31.9 mm Hg at FU2. In control eyes, the mean IOP was 7.2 to 12.6 mm Hg (FU1) and 8.9 to 16.0 mm Hg (FU2). At FU1, neuroretinal rim decreased and ALCS depth increased significantly (paired t-test, P < 0.01); no change in RNFL thickness was detected. At FU2, however, significant prelaminar tissue thinning, posterior displacement of NCO, and RNFL thinning were observed. Longitudinal SDOCT imaging can detect deep ONH changes in EG eyes, the earliest of which are present at the onset of HRT-detected ONH surface height depression. These parameters represent realistic targets for SDOCT detection of glaucomatous progression in human subjects.

Mixing Matrix Estimation From Sparse Mixtures With Unknown Number of Sources

In blind source separation, many methods have been proposed to estimate the mixing matrix by exploiting sparsity. However, they often need to know the source number a priori, which is very inconvenient in practice. In this paper, a new method, namely nonlinear projection and column masking (NPCM), is proposed to estimate the mixing matrix. A major advantage of NPCM is that it does not need any knowledge of the source number. In NPCM, the objective function is based on a nonlinear projection and its maxima just correspond to the columns of the mixing matrix. Thus a column can be estimated first by locating a maximum and then deflated by a masking operation. This procedure is repeated until the evaluation of the objective function decreases to zero dramatically. Thus the mixing matrix and the number of sources are estimated simultaneously. Because the masking procedure may result in some small and useless local maxima, particle swarm optimization (PSO) is introduced to optimize the objective function. Feasibility and efficiency of PSO are also discussed. Comparative experimental results show the efficiency of NPCM, especially in the cases where the number of sources is unknown and the sources are relatively less sparse.

Treatment of Allergic Conjunctivitis: Results of a 1-Month, Single-Masked Randomized Study

To compare the effects of topical antiallergic eyedrops in relieving the signs and symptoms of patients with allergic conjunctival pathology. In this multicenter, single-masked, randomized study, 240 patients with signs and symptoms of allergic conjunctivitis were randomized to receive 1 of the following 8 treatments twice daily: cromolyn sodium/chlorpheniramine maleate, diclofenac, epinastine, fluorometholone, ketotifen, levocabastine, naphazoline/antazoline, and olopatadine. Clinical signs and symptoms were evaluated by a masked operator using a 10-point scale at the moment of enrollment (day 0) and at weeks 1, 2, and 4. The percentage of patients achieving at least a small (at least 50% reduction of the total scale score) or a good (at least 75%) improvement of signs and symptoms was calculated at each visit. Tolerability was also evaluated as the duration of discomfort after instillation. All drugs gave some improvement in symptoms in more than 85% of cases. Epinastine and olopatadine obtained at least a good relief of symptoms in 37% and 33% of cases at week 1. At the end of the study, good improvement of symptoms was obtained in at least 70% of patients by epinastine, ketotifen, fluorometholone, and olopatadine, whereas a 75% improvement for signs was obtained only by fluorometholone and ketotifen. Naphazoline/antazoline induced higher discomfort compared to the other study treatments (p<0.0001). The efficacy of epinastine, ketotifen, and olopatadine in the treatment of allergic conjunctivitis was comparable to fluorometholone. Naphazoline/antazoline had lower tolerability than the other study treatments.

Two-level chaos-based video cryptosystem on H.263 codec

Chaos-based video encryption algorithms are designed based on selective encryption method. Different from many prevailing MPEG-based video encryption designs, this paper lays out a scheme for a two-level H.263-based video cryptosystem, which skillfully combines the traditional selective encryption algorithm with permutation and subsequent masking operation of the coded H.263-based stream. Lastly, the implementation of the proposed cryptosystem on a local area network (LAN) strongly illustrates the efficiency and feasibility of the two-level chaos-based cryptosystem for practical use in many respects, including processing speed, compression ratio, quality of reconstructed image and security level.

Macular Thickness Interoperator and Intraoperator Reproducibility in Healthy Eyes Using 7 Optical Coherence Tomography Instruments

To evaluate macular thickness measurement reproducibility using 6 new spectral-domain (SD) optical coherence tomography (OCT) devices and 1 time-domain OCT device Prospective, observational study. setting: Clinical practice. study population: Macular thickness was assessed in 18 randomly chosen consecutive eyes of 18 healthy volunteers by 2 masked operators using 6 SD OCT devices and 1 time-domain OCT device. main outcome measures: Intraoperator and interoperator reproducibility of OCT-measured central macular thickness. Mean macular thickness ranged from 172.77 to 272.87 microm. Intraobserver Intraclass coefficient correlation ranged from 0.75 to 0.96. Intraobserver coefficient of variation ranged from 0.44 to 2.75. In Bland-Altman analysis, interoperator mean difference ranged from 0.22 to -9.69. An analysis of variance used for repeated measurement was statistically significant for instruments (P < .001) and operators (P = .04), but not for instruments x operators (P = .32). The 7 OCT devices presented differing macular thickness measurement values; the lowest value was with Copernicus, and the highest was with Spectralis HRA+OCT (Heidelberg Engineering). The new generation of SD OCT devices has good intraoperator reproducibility, but the Spectralis presents the highest reproducibility together with the best interoperator agreement. The software, and in particular the algorithm, used is the most important factor regarding reproducibility differences in macular thickness measurement. The main result of our study is that macular thickness absolute value differs for each device. For this reason, the devices are not interchangeable.

Emergence of New Mechanical Functionality in Materials via Size Reduction

AbstractJulia R. Greer received her S.B. in Chemical Engineering from the Massachusetts Institute of Technology (1997) and a Ph.D. in Materials Science from Stanford University, where she worked on the nanoscale plasticity of gold with W. D. Nix (2005). She also worked at Intel Corporation in Mask Operations (2000–03) and was a post‐doctoral fellow at the Palo Alto Research Center (2005–07), where she worked on organic flexible electronics with R. A. Street. Greer is a recipient of TR‐35, Technology Review's Top Young Innovator award (2008), a NSF CAREER Award (2007), a Gold Materials Research Society Graduate Student Award (2004), and an American Association of University Women Fellowship (2003). Julia joined Caltech's Materials Science department in 2007 where she is developing innovative experimental techniques to assess mechanical properties of nanometer‐sized materials. One such approach involves the fabrication of nanopillars with different initial microstructures and diameters between 25 nm and 1 µm by using focused ion beam and electron‐beam lithography microfabrication. The mechanical response of these pillars is subsequently measured in a custom‐built in situ mechanical deformation instrument, SEMentor, comprising a scanning electron microscope and a nanoindenter. Read our interview with Prof. Greer on MaterialsViews.commagnified image

Searching for the dream embedded memory

In this paper, it was concluded that embedding memories into an SOC increases bandwidth, speed, and reliability of the overall system, while reducing power consumption and form factor. Embedded DRAM is an attractive choice for embedded memory because it consumes only 30% of standby power and 10% of active power, while it occupies only 30% of the area, compared to SRAM at the 90-nm CMOS node. At the same level of technology, embedded DRAM can achieve a soft-error rate of less than 1 FIT per Mb, which is ten to 1,000 times smaller than that of a comparable SRAM. However, a careful assessment of the benefits must be weighed against the increased process cost of four to six extra masks and masking operations. Emerging memories such as MRAM and PCRAM are nonvolatile with almost unlimited endurance and offer five orders of magnitude faster write speed than flash memory does, yet with read speed close to that of embedded DRAM. In addition, they are potentially simpler to fabricate. The MRAM cell is based on a multilayer magnetic tunnel junction with a parallel or antiparallel state to provide a 0 or1 logic state. The PCRAM cell is based on a reversible phase change between crystalline and amorphous states to provide a 0 or 1 state. These mechanisms have been proven in magnetic heads in hard disk drives and in readable/writable DVDs in discrete form. They are suitable for use as level-two or level-three cache or main memory or as storage devices for code or data. These emerging memories are about ready to be integrated into mainstream CMOS semiconductor processes.

Intra-Observer and Inter-Observer Reliability and Reproducibility of Slit-Lamp–Adapted Optical Coherence Tomography for Evaluation of Anterior Chamber Depth and Central Corneal Thickness

To evaluate the intra-observer and inter-observer reproducibility of anterior chamber depth (ACD) and central corneal thickness (CCT) measurements taken by slit-lamp-adapted optical coherence tomography (SL-OCT) and to evaluate concordance of CCT and ACD values obtained by SL-OCT with gold standard devices. Three images of each eye were taken by two different operators using SL-OCT. ACD and CCT values obtained by each operator were determined and compared to one another and to ultrasonic pachymetry (CCT) and axial OCT biometry (ACD) values obtained by a third, masked operator. Intra-observer and inter-operator reproducibility was assessed using the intraclass correlation coefficient (ICC). Forty-one eyes of healthy subjects were enrolled. Mean CCT was 0.556 +/- 0.020, 0.557 +/- 0.019, and 0.532 +/- 0.032 and mean ACD was 3.12 +/- 0.36, 3.13 +/- 0.38, and 3.50 +/- 0.44 for operators 1, 2, and 3, respectively (P < .001, for both CCT and ACD). Intra-operator reproducibility for CCT (ICC of 0.948 to 0.995) and ACD (ICC of 0.972 to 0.987) was excellent. SL-OCT provides highly reproducible measures for both CCT and ACD. SL-OCT yields higher values for CCT compared to ultrasonic pachymetry and lower values for ACD compared to axial OCT biometry. Caution should be taken when extrapolating these data into clinical practice until the differences between SL-OCT, axial OCT biometry, and ultrasonic pachymetry can be further elucidated.

Coastal dynamic and shoreline mapping: multi-sources spatial data analysis in Semarang Indonesia

Semarang coastal area has geomorphologically complex processes, such as erosion-sedimentation, land subsidence, and tidal inundation hazard. Multi-years shoreline mapping is considered a valuable task for coastal monitoring and assessment. This paper presents maps illustrating the shoreline dynamic in a coastal area of Semarang-Indonesia using multi-sources spatial data. The segment data has been obtained by visual delineation of the topographic maps Year 1908, 1937, 1992 and Ikonos image Year 2003 as well as digital number (DN) value analysis and masking operation of Landsat MSS Year 1972 and Landsat ETM Year 2001. For the long period of almost 100 year, the shoreline dynamic in Semarang coastal area is dominated by sedimentation process. Shoreline extended to the sea as a result of man-made infrastructure and natural processes. The research's result was satisfactory and the method has proven to be effective considering lack of homogeneous data-series. However, some further improvement regarding geo-processing can be made and the accuracy can be tested in future version.

A projection-based extension to phase correlation image alignment

Phase-correlation (PC) is a computationally efficient scheme for estimating 2-D and 3-D translations. We present a masking operator that significantly improves the accuracy and robustness of the PC scheme. The masking projects the estimated correlation function on the space of correlation functions that result from a certain range of translations, while rejecting components that are unrelated to the estimated motion. Thus, the registration accuracy is improved by an order of magnitude, especially when registering noisy images and volumes. The scheme is also shown to improve the registration of rotated images in the Fourier domain.

Advanced photolithographic mask repair using electron beams

Mask repair plays an important role in yielding advanced masks that support the lithography roadmap. It is also one of the more challenging parts of mask fabrication. Electron beam induced deposition and etching have shown great potential for mask repair applications. Our work has demonstrated that e-beam mask repair provides the superior resolution and damage-free process that is needed to support mask generations for the 32nm technology node and beyond. This article describes an installed e-beam mask repair tool at Intel Mask Operation and discusses the capabilities of this enabling technology based on results obtained from repairing masks with “defects” intentionally inserted into the design (programmed defect masks). Specifically, results are presented for quartz etch repair of alternating phase shift masks and TaBN absorber etch of extreme ultraviolet masks, two of the most difficult types of mask to repair using conventional methods.

Fast and Robust Image Matching by Selective Correlation Coefficient

An efficient algorithm for calculating Selective Correlation Coefficient (SCC) is proposed, which is expected as stable and robust for ill-conditions in imaging: illumination change, noise, and occlusion. The SCC is calculated through a masking operation based on Increment Sign Correlation which is efficient and robust for the ill- conditions. An SSDA algorithm and initial thresholding are introduced to remove redundant computation for obtaining much more efficiency. Through many experiments with real images, from twice to 150 times efficiency in comparison with CC and the original SCC could be obtained for ill-conditioned search problems.

A real time image processor for reproduction of gray levels in dark areas on plasma display panel (PDP)

Due to the non-balanced and linear luminous characteristics of RGB color channels of plasma display panels (PDPs), it is required to determine the white point of each gray level and perform inverse gamma correction. However, the two measures cause degradation of gray level representation and undesirable false contouring in the dark areas on PDPs. We describe the implementation of a real time image processor with an error diffusion algorithm and unsharp masking operation. Experimental results show improvements of gray level representation and reduction of undesirable false contouring on the PDP.

B-scan ultrasonography for the detection of macular thickening

PurposeTo report the sensitivity and specificity of B-scan ultrasonography to detect macular thickening. DesignObservational case series. MethodsSeventy-seven eyes of 40 consecutive patients (age range, 7–80 years) in a retinal specialty practice were examined. A single masked ultrasound operator performed B-scan ultrasonography on all eyes and graded macular thickening. The final assessment of macular thickening was based on biomicroscopy findings combined with fluorescein angiography (FA) and optical coherence tomography (OCT). The presence or absence of macular thickening as determined by B-scan ultrasonography was compared with the final clinical assessment, FA findings, and OCT measurements. ResultsB-scan ultrasonography detected macular thickening with a high degree of sensitivity (91%) and specificity (96%). There was a high degree of agreement between findings on ultrasonography and FA (kappa = 0.80). Ultrasonographic diagnosis correlated with OCT measurements for both central macular thickness (r = .65, P < .001) and volume (r = .56, P < .001). ConclusionsUltrasonographic detection of macular thickening correlates with findings on slit-lamp biomicroscopy, FA, and OCT. B-scan ultrasonography is a potentially useful technique for assessing macular thickness when biomicroscopy is impossible or when patients cannot tolerate FA or OCT.

Time-Frequency Analysis of Nonlinear Systems: The Skeleton Linear Model and the Skeleton Curves

The joint time-frequency analysis method is adopted to study the nonlinear behavior varying with the instantaneous response for a class of S.D.O.F nonlinear system. A time-frequency masking operator, together with the conception of effective time-frequency region of the asymptotic signal are defined here. Based on these mathematical foundations, a so-called skeleton linear model (SLM) is constructed which has similar nonlinear characteristics with the nonlinear system. Two skeleton curves are deduced which can indicate the stiffness and damping in the nonlinear system. The relationship between the SLM and the nonlinear system, both parameters and solutions, is clarified. Based on this work a new identification technique of nonlinear systems using the nonstationary vibration data will be proposed through time-frequency filtering technique and wavelet transform in the following paper.

Automated cerebrum segmentation from three-dimensional sagittal brain MR images

We present a fully automated cerebrum segmentation algorithm for full three-dimensional sagittal brain MR images. First, cerebrum segmentation from a midsagittal brain MR image is performed utilizing landmarks, anatomical information, and a connectivity-based threshold segmentation algorithm as previously reported. Recognizing that cerebrum in laterally adjacent slices tends to have similar size and shape, we use the cerebrum segmentation result from the midsagittal brain MR image as a mask to guide cerebrum segmentation in adjacent lateral slices in an iterative fashion. This masking operation yields a masked image (preliminary cerebrum segmentation) for the next lateral slice, which may truncate brain region(s). Truncated regions are restored by first finding end points of their boundaries, by comparing the mask image and masked image boundaries, and then applying a connectivity-based algorithm. The resulting final extracted cerebrum image for this slice is then used as a mask for the next lateral slice. The algorithm yielded satisfactory fully automated cerebrum segmentations in three-dimensional sagittal brain MR images, and had performance superior to conventional edge detection algorithms for segmentation of cerebrum from 3D sagittal brain MR images.

Identification of nonlinear dynamic systems: Time-frequency filtering and skeleton curves

The nonlinear behavior varying with the instantaneous response was analyzed through the joint time-frequency analysis method for a class of S. D. O. F nonlinear system. A masking operator on definite regions is defined and two theorems are presented. Based on these, the nonlinear system is modeled with a special time-varying linear one, called the generalized skeleton linear system (GSLS). The frequency skeleton curve and the damping skeleton curve are defined to describe the main feature of the non-linearity as well. Moreover, an identification method is proposed through the skeleton curves and the time-frequency filtering technique.