Single Threshold Value Research Articles

Normal Development and Measurements of the Occipital Condyle-C1 Interval in Children and Young Adults

Widening of the occipital condyle-C1 interval is the most specific and sensitive means of detecting atlanto-occipital dislocation. Recent studies attempting to define normal measurements of the condyle-C1 interval in children have varied substantially. This study was performed to test the null hypothesis that condyle-C1 interval morphology and joint measurements do not change as a function of age. Imaging review of subjects undergoing CT of the upper cervical spine for reasons unrelated to trauma or developmental abnormality was performed. Four equidistant measurements were obtained for each bilateral condyle-C1 interval on sagittal and coronal images. The cohort was divided into 7 age groups to calculate the mean, SD, and 95% CIs for the average condyle-C1 interval in both planes. The prevalence of a medial occipital condyle notch was calculated. Two hundred forty-eight joints were measured in 124 subjects with an age range of 2 days to 22 years. The condyle-C1 interval varies substantially by age. Average coronal measurements are larger and more variable than sagittal measurements. The medial occipital condyle notch is most prevalent from 1 to 12 years and is uncommon in older adolescents and young adults. The condyle-C1 interval increases during the first several years of life, is largest in the 2- to 4-year age range, and then decreases through late childhood and adolescence. A single threshold value to detect atlanto-occipital dissociation may not be sensitive and specific for all age groups. Application of this normative data to documented cases of atlanto-occipital injury is needed to determine clinical utility.

Assignment of Exciton Domain in Light Harvesting Systems Based on the Variational Polaron Approach.

In large light harvesting systems, not all pigments are coupled strongly. This is evidenced by the formation of delocalized states in certain domains of strongly coupled pigments. The threshold value for assigning pigments to domains is usually defined, and the pigment pairs in which the electronic coupling is greater than this value are included in the same domain to describe the dynamic localization effect implicitly. However, domain assignment by a single threshold value may make it difficult to include the possible localization of exciton states by temperature and the difference in the electronic excitation energy between pigments. In this study, we use the variational polaron approach for domain assignment to include such possible localization. To demonstrate the validity of domain assignment by the variational approach, we applied it to pigments in photosystem II (PSII) and compared the domain model constructed by the single threshold value. We showed that domain assignment by the variational approach could be used to determine the valid domain model in PSII without using the empirical threshold value at least at 77 K.

A Comparative Study of Binarization Techniques for Enhancement of Degraded Documents

Documents are archived and preserved in large quantities worldwide. Electronic scanning is a common approach in handling such materials to facilitate public access to them. But the resulting images are often difficult to read, also have low contrast, and are corrupted by different artifacts. Enhancement of image is normally based on minor deterioration in modern documents to improve optical character recognition. It often ignores cases, such as those typical of historical and other highly degraded documents. Separating background and foreground can make an image readable. The initial approach is using local threshold where an average threshold value is used for sub images. The next approach is using Global thresholding where only single threshold value is used for an entire image. The third approach is combining both the algorithms Local and Global which is Hybrid Binarization where global thresholding is applied and Local thresholding is applied to parts where thresholding is to be done. The last approach being Iterative Global Thresholding which calculates the threshold iteratively and performs thresholding. Filtering is done to remove noises using methods like Smoothing and Sharpening and Peak to signal noise ratio is found before and after to check the degree of enhancement.

A local fuzzy thresholding methodology for multiregion image segmentation

Thresholding is a direct and simple approach to extract different regions from an image. In its basic formulation, thresholding searches for a global value that maximizes the separation between output classes. The use of a single hard threshold value is precisely the source of important segmentation errors in many scenarios like noisy images or uneven illumination. If no connectivity or closed objects are considered, the method is prone to produce isolated pixels. In this paper a new multiregion thresholding methodology is presented to overcome the common drawbacks of thresholding methods when images are corrupted with artifacts and noise. It is based on relating each pixel in the image to different output centroids via a fuzzy membership function, avoiding any initial hard decision. The starting point of the technique is the definition of the output centroids using a clustering method compatible with most thresholding techniques in the literature. The method makes use of the spatial information through a local aggregation step where the membership degree of each pixel is modified by local information that takes into account the memberships of the surrounding pixels. This makes the method robust to noise and artifacts. The general formulation of the proposed methodology allows the design of spatial aggregations for multiple applications, including the possibility of including heuristic information via a fuzzy inference rule base.

Threshold Analysis of Wavelet Based Fingerprint Feature Extraction Methods on Multiple Impression Dataset

In recent years, fingerprint recognition has been moving through series of evolutions with the intent to decrease the False Acceptance Rate (FAR) and the False Rejection Rate (FRR) in order to achieve minimum Equal Error Rate (EER) while increasing recognition rate. In practical cases, fingerprint images stored in fingerprint databases may have come from scanners with different specifications under variant environmental conditions which may produce different or multiple impressions and backgrounds. The choice of what single and acceptable threshold value to use in order to characterize fingerprint features in images for recognition is therefore crucial in establishing a minimal EER. In this paper, we investigate and analyze the effect of several threshold values on EER when several families of wavelets based methods for feature extraction are applied on multiple impression datasets (Fingerprint Verification Competition-FVC2004). After conducting several threshold analysis on extracted features from multiple impression dataset, the results show

A progressive black top hat transformation algorithm for estimating valley volumes on Mars

The depth of valley incision and valley volume are important parameters in understanding the geologic history of early Mars, because they are related to the amount sediments eroded and the quantity of water needed to create the valley networks (VNs). With readily available digital elevation model (DEM) data, the Black Top Hat (BTH) transformation, an image processing technique for extracting dark features on a variable background, has been applied to DEM data to extract valley depth and estimate valley volume. Previous studies typically use a single window size for extracting the valley features and a single threshold value for removing noise, resulting in finer features such as tributaries not being extracted and underestimation of valley volume. Inspired by similar algorithms used in LiDAR data analysis to remove above-ground features to obtain bare-earth topography, here we propose a progressive BTH (PBTH) transformation algorithm, where the window size is progressively increased to extract valleys of different orders. In addition, a slope factor is introduced so that the noise threshold can be automatically adjusted for windows with different sizes. Independently derived VN lines were used to select mask polygons that spatially overlap the VN lines. Volume is calculated as the sum of valley depth within the selected mask multiplied by cell area. Application of the PBTH to a simulated landform (for which the amount of erosion is known) achieved an overall relative accuracy of 96%, in comparison with only 78% for BTH. Application of PBTH to Ma’adim Vallies on Mars not only produced total volume estimates consistent with previous studies, but also revealed the detailed spatial distribution of valley depth. The highly automated PBTH algorithm shows great promise for estimating the volume of VN on Mars on global scale, which is important for understanding its early hydrologic cycle.

Detection of Thrips Defect on Green-Peel Citrus Using Hyperspectral Imaging Technology Combining PCA and B-Spline Lighting Correction Method

In order to find an effective method of detecting thrips defect on green-peel citrus, a defect segmentation method was developed using a single threshold value based on combination of characteristic wavelengths principal component analysis (PCA) and B-spline lighting correction method in this study. At first, four characteristic wavelengths (523, 587, 700 and 768 nm) were obtained using PCA of Vis-NIR (visible and near-infrared) bands and analysis of weighting coefficients; secondarily, PCA was performed using characteristic wavelengths and the second principal component (PC2) was selected to classify images; then, B-spline lighting correction method was proposed to overcome the influence of lighting non-uniform on citrus when thrips defect was segmented; finally, thrips defect on citrus was extracted by global threshold segmentation and morphological image processing. The experimental results show that thrips defect in citrus can be detected with an accuracy of 96.5% by characteristic wavelengths PCA and B-spline lighting correction method. This study shows that thrips defect on green-peel citrus can be effectively identified using hyperspectral imaging technology.

Detrusor contraction power parameters (BCI and W max) rise with increasing bladder outlet obstruction grade in men with lower urinary tract symptoms: results from a urodynamic database analysis.

To investigate to what extent detrusor work during voiding is influenced by bladder outlet obstruction (BOO) in adult men with lower urinary tract symptoms (LUTS). We reviewed data of patients with LUTS suggestive of benign prostatic hyperplasia who received computer-urodynamic investigations as part of their baseline clinical assessment. BOO was defined by the Schäfer classification and detrusor work during voiding was quantified by calculation of the bladder contractility index (BCI) and maximum Watt factor (W max) obtained by pressure-flow analysis. A total of 786 men with medians of 64 years, IPSS 16 and prostate volume of 35 ml, were included in the study. A total of 462 patients (58.8 %) had BOO (Schäfer 2-6). Both detrusor contraction power parameters continuously increased with rising BOO grade. Median BCI increased from 73.3 in Schäfer 0 to 188.0 in Schäfer 6, whereas W max increased from 9.6 to 23.4 W/m(2) (p < 0.001). Results of BCI and W max correlated well (p < 0.001). With increasing BOO grade, there was a significant decrease of voiding efficiency (p < 0.001). In adult male LUTS patients, detrusor contraction power parameters-BCI and W max-continuously increase with rising BOO grade. According to our results, it is impossible to determine a single threshold value for detrusor contraction power to diagnose detrusor underactivity in a group of LUTS patients with different BOO grades. The study is limited to men with non-neurogenic LUTS. Future studies should evaluate exact threshold values for BCI and W max in BOO subgroups to adequately define detrusor underactivity and investigate men with other bladder conditions.

MP76-10 OBSTRUCTION DEPENDENT BLADDER CONTRACTILITY - RESULTS FROM A LARGE URODYNAMIC CROSS-SECTIONAL STUDY IN MEN WITH LOWER URINARY TRACT SYMPTOMS

You have accessJournal of UrologyUrodynamics/Incontinence/Female Urology: Non-neurogenic Voiding Dysfunction1 Apr 2014MP76-10 OBSTRUCTION DEPENDENT BLADDER CONTRACTILITY - RESULTS FROM A LARGE URODYNAMIC CROSS-SECTIONAL STUDY IN MEN WITH LOWER URINARY TRACT SYMPTOMS Kevin Rademakers, Gommert van Koeveringe, and Matthias Oelke Kevin RademakersKevin Rademakers More articles by this author , Gommert van KoeveringeGommert van Koeveringe More articles by this author , and Matthias OelkeMatthias Oelke More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.2403AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES There is much controversy defining detrusor contractility correctly. Earlier studies with experimental animals showed an increase in detrusor contraction power with increasing bladder outlet obstruction (BOO) in the compensated phase of the urinary bladder compared to non-obstructed bladders. Therefore, the aim of this study was to prove whether detrusor contraction power is increased in men with BOO and to what extend different BOO grades are associated with different levels of contractility. METHODS In this cross-sectional study we included male patients with uncomplicated LUTS but without signs of prostate cancer. All men received computer-urodynamic investigations as part of their baseline clinical assessment. The Schäfer-classification was used to determine BOO-grades (Schäfer 0-6) and detrusor contractility was quantified by calculation of the bladder contractility index (BCI) and maximum Watt factor (Wmax) obtained by pressure-flow analysis. Results were statistically analyzed in SPSS 18 using the Mann-Whitney U test. RESULTS The study population consisted of 786 men with a median age of 64 years (interquartile range [IQR] 59-70), IPSS 16 (IQR 11-21) and prostate volume of 37 cc (IQR 28-50). 462 patients (59%) had BOO in pressure-flow analysis (Schäfer 2-6). Both detrusor contractility parameters (BCI and Wmax) continuously rose with increasing BOO grade (Figure). Median BCI ranged from 73.3 in Schäfer 0 to 188.0 in Schäfer 6, whereas Wmax increased from 9.6 to 23.4 W/m2. In addition, there was a significant difference in BCI and Wmax when comparing non-BOO (Schäfer 0-1) with BOO patients (Schäfer 2-6), p<0.01. CONCLUSIONS Along with increasing BOO-grade, detrusor contraction power parameters –BCI and Wmax– continuously increased in a large group of male LUTS patients. We could, for the first time, confirm data obtained from animal studies in humans for the first time. Therefore, in a group of LUTS patients with different BOO grades, it is impossible to determine a single threshold value for detrusor contraction power to diagnose detrusor underactivity. Exact threshold values for BCI or Wmax in the subgroups of BOO have to be determined in future studies to define detrusor underactivity. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e885 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Kevin Rademakers More articles by this author Gommert van Koeveringe More articles by this author Matthias Oelke More articles by this author Expand All Advertisement Advertisement PDF DownloadLoading ...

Probabilistic approach to cloud and snow detection on Advanced Very High Resolution Radiometer (AVHRR) imagery

Abstract. Derivation of probability estimates complementary to geophysical data sets has gained special attention over the last years. Information about a confidence level of provided physical quantities is required to construct an error budget of higher-level products and to correctly interpret final results of a particular analysis. Regarding the generation of products based on satellite data a common input consists of a cloud mask which allows discrimination between surface and cloud signals. Further the surface information is divided between snow and snow-free components. At any step of this discrimination process a misclassification in a cloud/snow mask propagates to higher-level products and may alter their usability. Within this scope a novel probabilistic cloud mask (PCM) algorithm suited for the 1 km × 1 km Advanced Very High Resolution Radiometer (AVHRR) data is proposed which provides three types of probability estimates between: cloudy/clear-sky, cloudy/snow and clear-sky/snow conditions. As opposed to the majority of available techniques which are usually based on the decision-tree approach in the PCM algorithm all spectral, angular and ancillary information is used in a single step to retrieve probability estimates from the precomputed look-up tables (LUTs). Moreover, the issue of derivation of a single threshold value for a spectral test was overcome by the concept of multidimensional information space which is divided into small bins by an extensive set of intervals. The discrimination between snow and ice clouds and detection of broken, thin clouds was enhanced by means of the invariant coordinate system (ICS) transformation. The study area covers a wide range of environmental conditions spanning from Iceland through central Europe to northern parts of Africa which exhibit diverse difficulties for cloud/snow masking algorithms. The retrieved PCM cloud classification was compared to the Polar Platform System (PPS) version 2012 and Moderate Resolution Imaging Spectroradiometer (MODIS) collection 6 cloud masks, SYNOP (surface synoptic observations) weather reports, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) vertical feature mask version 3 and to MODIS collection 5 snow mask. The outcomes of conducted analyses proved fine detection skills of the PCM method with results comparable to or better than the reference PPS algorithm.

Decision analysis for the genotype designation in low-template-DNA profiles

What genotype should the scientist specify for conducting a database search to try to find the source of a low-template-DNA (lt-DNA) trace? When the scientist answers this question, he or she makes a decision. Here, we approach this decision problem from a normative point of view by defining a decision-theoretic framework for answering this question for one locus. This framework combines the probability distribution describing the uncertainty over the trace's donor's possible genotypes with a loss function describing the scientist's preferences concerning false exclusions and false inclusions that may result from the database search. According to this approach, the scientist should choose the genotype designation that minimizes the expected loss. To illustrate the results produced by this approach, we apply it to two hypothetical cases: (1) the case of observing one peak for allele xi on a single electropherogram, and (2) the case of observing one peak for allele xi on one replicate, and a pair of peaks for alleles xi and xj, i ≠ j, on a second replicate. Given that the probabilities of allele drop-out are defined as functions of the observed peak heights, the threshold values marking the turning points when the scientist should switch from one designation to another are derived in terms of the observed peak heights. For each case, sensitivity analyses show the impact of the model's parameters on these threshold values. The results support the conclusion that the procedure should not focus on a single threshold value for making this decision for all alleles, all loci and in all laboratories.

Critical assessment of the 2°c-min−1 threshold for thermal stress weathering

Rock surface temperature changes in excess of 2°C-min−1 have been argued to result in permanent strain in rock. The single threshold value and the supposed importance of a rate of 2°C-min−1 rock temperature change is rejected, based on lack of a sufficient empirical basis, contrasting results from acoustic emission studies, varying strength properties of different rock types, lack of data on actual strain resulting from short‐term temperature variations, and lack of notable long‐term weathering effects in ordic environments. Based on the presented discussion, the role of thermal shock weathering in cold regions is questioned and renewed emphasis is placed on the importance of absolute temperature and measurement of strain, as well as spatial temperature gradients.

Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects

Soil organic carbon (SOC) is a potential soil fertility indicator for regulating nitrogen application in tropical farming systems. However, there are limited studies that have discussed SOC thresholds above or below which crop production could be diminished, or at which no or high response to nitrogen (N) application can be realized. This review explores the drivers of SOC concentration relevant for the establishment of thresholds. We further evaluate existing SOC thresholds for provoking no yield response or significant response to added N fertilizer. Key drivers for SOC concentration relevant in establishing thresholds are mainly climate, topography, texture, and land use management. Soil organic carbon threshold for sustaining soil quality is widely suggested to be about 2% below which deterioration may occur. For added N fertilizer management, specific SOC thresholds seem quite complex and are only valid after assuming other factors are non-limiting. In some soils, SOC levels as low as 0.5% result in fertilizer responses and soils as high as 2% SOC also respond to small N doses. Minimum SOC thresholds can be identified for a given soil type, but maximum thresholds depend on crop N requirements, crop N use efficiency and amount of N applied. However, there seem to exist critical total SOC ranges that could be targeted for optimal indigenous N supply and integrative soil functional benefits. These can be targeted as minimum levels in soil fertility restoration. In all, it is still difficult to establish a single minimum or maximum SOC threshold value that can be universally or regionally accepted.

Neighborhood-scale air quality impacts of emissions from motor vehicles and aircraft

A mobile monitoring platform (MMP) was used to measure real-time air pollutant concentrations in different built environments of Boyle Heights (BH, a lower-income community enclosed by several freeways); Downtown Los Angeles (DTLA, adjacent to BH with taller buildings and surrounded by several freeways); and West Los Angeles (WLA, an affluent community traversed by two freeways) in summer afternoons of 2008 and 2011 (only for WLA). Significant inter-community and less significant but observable intra-community differences in traffic-related pollutant concentrations were observed both in the residential neighborhoods studied and on their arterial roadways between BH, DTLA, and WLA, particularly for ultrafine particles (UFP). HEV, defined as vehicles creating plumes with concentrations more than three standard deviations from the adjusted local baseline, were encountered during 6–13% of sampling time, during which they accounted for 17–55% of total UFP concentrations both on arterial roadways and in residential neighborhoods. If instead a single threshold value is used to define HEVs in all areas, HEV's were calculated to make larger contributions to UFP concentrations in BH than other communities by factors of 2–10 or more. Santa Monica Airport located in WLA appears to be a significant source for elevated UFP concentrations in nearby residential neighborhoods 80–400 m downwind. In the WLA area, we also showed, on a neighborhood scale, striking and immediate reductions in particulate pollution (∼70% reductions in both UFP and, somewhat surprisingly, PM2.5), corresponding to dramatic decreases in traffic densities during an I-405 closure event (“Carmageddon”) compared to non-closure Saturday levels. Although pollution reduction due to decreased traffic is not unexpected, this dramatic improvement in particulate pollution provides clear evidence air quality can be improved through strategies such as heavy-duty-diesel vehicle retrofits, earlier retirement of HEV, and transition to electric vehicles and alternative fuels, with corresponding benefits for public health.

ITS1 versus ITS2 as DNA metabarcodes for fungi

The nuclear ribosomal Internal Transcribed Spacer ITS region is widely used as a DNA metabarcoding marker to characterize the diversity and composition of fungal communities. In amplicon pyrosequencing studies of fungal diversity, one of the spacers ITS1 or ITS2 of the ITS region is normally used. In this methodological study we evaluate the usability of ITS1 vs. ITS2 as a DNA metabarcoding marker for fungi. We analyse three data sets: two comprising ITS1 and ITS2 sequences of known taxonomic affiliations and a third comprising ITS1 and ITS2 environmental amplicon pyrosequencing data. Clustering analyses of sequences with known taxonomy using the bioinformatics pipeline ClustEx revealed that a 97% similarity cut-off represent a reasonable threshold for estimating the number of known species in the data sets for both ITS1 and ITS2. However, no single threshold value worked well for all fungi at the same time within the curated UNITE database, and we found that the Operational Taxonomic Unit (OTU) concept is not easily translated into the level of species because many species are distributed over several clusters. Clustering analyses of the 134692 ITS1 and ITS2 pyrosequences using a 97% similarity cut-off revealed a high similarity between the two data sets when it comes to taxonomic coverage. Although some groups are under- or unrepresented in the two data sets due to, e.g. primer mismatches, our results indicate that ITS1 and ITS2 to a large extent yield similar results when used as DNA metabarcodes for fungi.

Real-Time near Infrared Spectral Monitoring of Mammary Gland for Inflammation Diagnosis in Dairy Cows

The diagnosis of cow mastitis was performed using shortwave near infrared (NIR) spectroscopy of cow udder tissue collected at morning milking over a two-year period in order to investigate the influence of various factors such as season, udder position, cow identity etc. The NIR spectra were acquired using a portable NIR spectrometer and quarter foremilk was collected and analysed for milk components as reference data. The somatic cell count (SCC) was mainly used for mastitis diagnosis. The analysis of in vivo shortwave NIR spectral data of udder tissue was carried out using the soft independent modelling of class analogy (SIMCA) classification method. First, the influence of the difference in udder location on the spectral data were investigated. The SIMCA calibration revealed that spectra for different udder locations, such as front vs rear and right vs left udder quarter, enabled different prediction accuracy. SIMCA classification for mastitis diagnosis based on the SCC value was performed for the whole udder and for the front and rear quarter spectra, separately. In order to find the accurate threshold for mastitis using only spectral data, a single threshold value of SCC for recognition of mastitis was increased in steps of 10,000 cells mL−1 from 100,000 to 200,000 cells mL−1 and then SIMCA was applied for spectral data analysis. As a result, the best SIMCA prediction for the whole udder, 60.9% of sensitivity and 68.6% of specificity, was obtained for the SCC threshold of 110,000 cells mL−1. In contrast, the prediction result for front and rear quarter spectra showed different classification results. For the front udder quarter, a best prediction accuracy of 75.0% of sensitivity and 84.6% of specificity was obtained when using 160,000 cells mL−1 of SCC as the threshold, while the rear quarter spectra showed 100.0% of sensitivity and 84.7% of specificity with the same threshold for SCC as for front udder (160,000 cells mL−1). The highest classification accuracy of mammary gland inflammation diagnosis was obtained when front and rear udders were analysed separately.

Great Salt Lake–Effect Precipitation: Observed Frequency, Characteristics, and Associated Environmental Factors

Abstract This climatology examines the environmental factors controlling the frequency, occurrence, and morphology of Great Salt Lake–effect (GSLE) precipitation events using cool season (16 September–15 May) Weather Surveillance Radar-1988 Doppler (WSR-88D) imagery, radiosonde soundings, and MesoWest surface observations from 1997/98 to 2009/10. During this period, the frequency of GSLE events features considerable interannual variability that is more strongly correlated to large-scale circulation changes than lake-area variations. Events are most frequent in fall and spring, with a minimum in January when the climatological lake surface temperature is lowest. Although forecasters commonly use a 16°C lake–700-hPa temperature difference (ΔT) as a threshold for GSLE occurrence, GSLE was found to occur in winter when ΔT was only 12.4°C. Conversely, GSLE is associated with much higher values of ΔT in the fall and spring. Therefore, a seasonally varying threshold based on a quadratic fit to the monthly minimum ΔT values during GSLE events is more appropriate than a single threshold value. A probabilistic forecast method based on the difference between ΔT and this seasonally varying threshold, 850–700-hPa relative humidity, and 700-hPa wind direction offers substantial improvement over existing methods, although forecast skill is diminished by temperature and moisture errors in operational models. An important consideration for forecasting because of their higher precipitation rates, banded features—with a horizontal aspect ratio of 6:1 or greater—dominate only 20% of the time that GSLE is occurring, while widespread, nonbanded precipitation is much more common. Banded periods are associated with stronger low-level winds and a larger lake–land temperature difference.

Mapping spatio-temporal changes of Chinese electric power consumption using night-time imagery

China's rapid economic development in the last 20 years has resulted in increased demand for electricity and ensuing shortages in electric power supply. It is necessary to derive accurate and timely information regarding changing spatio-temporal patterns and trends of electric power consumption to inform future electricity allocation. Night-time annual image composites for 1995–2005 were obtained from the Defense Meteorological Satellite Program's Operational Linescan System and were inter-calibrated. The inter-calibrated night-time image composites were used in conjunction with the LandScan 2008 population data to estimate the amounts of electric power consumption in 1995, 2000 and 2005 for China at the province level. The estimated amounts of electric power consumption were then disaggregated to the pixel level. A pixel-based map was produced to show the spatio-temporal changes of electric power consumption from 1995 to 2005, in which 11 regional agglomerations with large increases of electric power consumption had emerged. During the process of producing this spatio-temporal change map, some errors were generated because of the use of single-year LandScan population data, imperfect reference regions for inter-calibration and a single threshold value for delimiting urban areas. However, we believe these errors are limited and acceptable, so we present this method of estimation and disaggregation to show the increases in electric consumption.

Analysis of stochastic magnetic fields formed by the application of resonant magnetic perturbations on MAST and comparison with experiment

In MAST experiments with applied resonant magnetic perturbations (RMPs), clear reduction in line-averaged density has been observed in a wide range of L-mode plasmas when there is an alignment between the perturbation and the equilibrium magnetic field that maximizes the size of the resonant components of the applied magnetic field, as well as in a few H-mode plasmas but with a much stronger sensitivity to this alignment. This density pump-out is the result of increased particle transport, which is thought to be caused by the formation of a stochastic magnetic field in the plasma edge. This paper presents an analysis of the magnetic field structures formed by the application of n = 3 RMPs on MAST, including various parameters characterizing the degree of stochasticity in the plasma edge. Values for these parameters are calculated and compared with the amount of density pump-out observed in MAST experiments. It is found that density pump-out is fairly well correlated with some of the parameters calculated using vacuum modelling, but none of them provides a single threshold value for pump-out that applies to both L- and H-mode plasmas. Plasma response modelling provides a robust criterion for density pump-out that applies both to L- and H-mode plasmas.

SEGMENTING THE EYE FUNDUS IMAGES FOR IDENTIFICATION OF BLOOD VESSELS

Retinal (eye fundus) images are widely used for diagnostic purposes by ophthalmologists. The normal features of eye fundus images include the optic nerve disc, fovea and blood vessels. Algorithms for identifying blood vessels in the eye fundus image generally fall into two classes: extraction of vessel information and segmentation of vessel pixels. Algorithms of the first group start on known vessel point and trace the vasculature structure in the image. Algorithms of the second group perform a binary classification (vessel or non-vessel, i.e. background) in accordance of some threshold. We focus here on the binarization [4] methods that adapt the threshold value on each pixel to the global/local image characteristics. Global binarization methods [5] try to find a single threshold value for the whole image. Local binarization methods [3] compute thresholds individually for each pixel using information from the local neighborhood of the pixel. In this paper, we modify and improve the Sauvola local binarization method [3] by extending its abilities to be applied for eye fundus pictures analysis. This method has been adopted for automatic detection of blood vessels in retinal images. We suggest automatic parameter selection for Sauvola method. Our modification allows determine/extract the blood vessels almost independently of the brightness of the picture.