436 research outputs found
An Image Retrieval System Based on the Color Complexity of Images
The fuzzy color histogram (FCH) spreads each pixel's total membership value to all histogram bins based on their color similarity. The FCH is insensitive to quantization errors. However, the FCH can state only the global properties of an image rather than the local properties. For example, it cannot depict the color complexity of an image. To characterize the color complexity of an image, this paper presents two image features -- the color variances among adjacent segments (CVAAS) and the color variances of the pixels within an identical segment (CVPWIS). Both features can explain not only the color complexity but also the principal pixel colors of an image. Experimental results show that the CVAAS and CVPWIS based image retrieval systems can provide a high accuracy rate for finding out the database images that satisfy the users' requirement. Moreover, both systems can also resist the scale variances of images as well as the shift and rotation variances of segments in images
Motor neuron-derived Thsd7a is essential for zebrafish vascular development via the Notch-dll4 signaling pathway.
BackgroundDevelopment of neural and vascular systems displays astonishing similarities among vertebrates. This parallelism is under a precise control of complex guidance signals and neurovascular interactions. Previously, our group identified a highly conserved neural protein called thrombospondin type I domain containing 7A (THSD7A). Soluble THSD7A promoted and guided endothelial cell migration, tube formation and sprouting. In addition, we showed that thsd7a could be detected in the nervous system and was required for intersegmental vessels (ISV) patterning during zebrafish development. However, the exact origin of THSD7A and its effect on neurovascular interaction remains unclear.ResultsIn this study, we discovered that zebrafish thsd7a was expressed in the primary motor neurons. Knockdown of Thsd7a disrupted normal primary motor neuron formation and ISV sprouting in the Tg(kdr:EGFP/mnx1:TagRFP) double transgenic zebrafish. Interestingly, we found that Thsd7a morphants displayed distinct phenotypes that are very similar to the loss of Notch-delta like 4 (dll4) signaling. Transcript profiling further revealed that expression levels of notch1b and its downstream targets, vegfr2/3 and nrarpb, were down-regulated in the Thsd7a morphants. These data supported that zebrafish Thsd7a could regulate angiogenic sprouting via Notch-dll4 signaling during development.ConclusionsOur results suggested that motor neuron-derived Thsd7a plays a significant role in neurovascular interactions. Thsd7a could regulate ISV angiogenesis via Notch-dll4 signaling. Thus, Thsd7a is a potent angioneurin involved in the development of both neural and vascular systems
An Automatic Indirect Immunofluorescence Cell Segmentation System
Indirect immunofluorescence (IIF) with HEp-2 cells has been used for the detection of antinuclear autoantibodies (ANA) in systemic autoimmune diseases. The ANA testing allows us to scan a broad range of autoantibody entities and to describe them by distinct fluorescence patterns. Automatic inspection for fluorescence patterns in an IIF image can assist physicians, without relevant experience, in making correct diagnosis. How to segment the cells from an IIF image is essential in developing an automatic inspection system for ANA testing. This paper focuses on the cell detection and segmentation; an efficient method is proposed for automatically detecting the cells with fluorescence pattern in an IIF image. Cell culture is a process in which cells grow under control. Cell counting technology plays an important role in measuring the cell density in a culture tank. Moreover, assessing medium suitability, determining population doubling times, and monitoring cell growth in cultures all require a means of quantifying cell population. The proposed method also can be used to count the cells from an image taken under a fluorescence microscope
Comparison of secondary signs as shown by unenhanced helical computed tomography in patients with uric acid or calcium ureteral stones
AbstractUnenhanced helical computed tomography (UHCT) has evolved into a well-accepted diagnostic method in patients with suspected ureterolithiasis. UHCT not only shows stones within the lumen of the ureter, it also permits evaluation of the secondary signs associated with ureteral obstruction from stones. However, there we could find no data on how secondary signs might differ in relation to different compositions of ureteral stones. In this study, we compared the degree of secondary signs revealed by UHCT in uric acid stone formers and in patients forming calcium stones. We enrolled 117 patients with ureteral stones who underwent UHCT examination and Fourier transform infra-red analysis of stone samples. Clinical data were collected as follows: age, sex, estimated glomerular filtration rate (eGFR), urine pH, and radiological data on secondary signs apparent on UHCT. The uric acid stone formers had significantly lower urine pH and eGFR in comparison to calcium stone formers, and on UHCT they also had a higher percentage of the secondary signs, including rim sign (78.9% vs. 60.2%), hydroureter (94.7% vs. 89.8%), perirenal stranding (84.2% vs. 59.2%) and kidney density difference (73.7% vs. 50.0%). The radiological difference was statistically significant for perirenal stranding (p=0.041). In conclusion, we found that UHCT scanning reveals secondary signs to be more frequent in patients with uric acid ureteral stones than in patients with calcium stones, a tendency that might result from an acidic urine environment
A Study on Integration of Energy Harvesting System and Semi-Active Control for a Hydraulic Suspension System
Suspension systems are used to diminish the vibration of vehicles. The hydraulic dampers in conventional suspension systems are mainly designed with the orifices of the piston; however, the vibration energy will be transferred into waste heat. In recent years, conventional vehicles with internal combustion engines and hybrid vehicles are used commonly. However, with the gradual depletion of fossil fuels, electric vehicles are developing. For this reason, the research focuses on recycling energy from the suspension of vehicles to improve the vehicle’s endurance. The purpose of this study is to develop a semi-active suspension control system with an energy harvesting system. Instead of the fixed orifices in conventional vehicles, an adjusting damping force method with variable resistance circuits system is studied for the semi-active suspension control system. Thus, we are able to develop semi-active control to improve the riding comfort. The energy harvesting system contains a hydraulic gear motor and a DC generator. When vehicles vibrate, the hydraulic damper serves as a hydraulic pump to compress the oil and drive the hydraulic motor. At the same time, the hydraulic motor drives the generator to generate electricity which will be stored in a battery. In this study, the test rig is the quarter-car system. We first design the novel hydraulic suspension system combining with the energy harvesting system. The simulation of dynamic mathematical model will be performed and analyzed by MATLAB/Simulink. Besides that, the semiactive control by the fuzzy sliding mode controller will be realized in the hydraulic suspension system with energy harvesting system. Finally, a test rig is set up for practical experimental implementation and verification
Continuous Production of Lipase-Catalyzed Biodiesel in a Packed-Bed Reactor: Optimization and Enzyme Reuse Study
An optimal continuous production of biodiesel by methanolysis of soybean oil in a packed-bed reactor was developed using immobilized lipase (Novozym 435) as a catalyst in a tert-butanol solvent system. Response surface methodology (RSM) and Box-Behnken design were employed to evaluate the effects of reaction temperature, flow rate, and substrate molar ratio on the molar conversion of biodiesel. The results showed that flow rate and temperature have significant effects on the percentage of molar conversion. On the basis of ridge max analysis, the optimum conditions were as follows: flow rate 0.1 mL/min, temperature 52.1°C, and substrate molar ratio 1 : 4. The predicted and experimental values of molar conversion were 83.31 ± 2.07% and 82.81 ± .98%, respectively. Furthermore, the continuous process over 30 days showed no appreciable decrease in the molar conversion. The paper demonstrates the applicability of using immobilized lipase and a packed-bed reactor for continuous biodiesel synthesis
Internal solitons in the northeastern south China Sea. Part I: sources and deep water propagation
Author Posting. © IEEE, 2004. This article is posted here by permission of IEEE for personal use, not for redistribution. The definitive version was published in IEEE Journal of Oceanic Engineering 29 (2004): 1157-1181, doi:10.1109/JOE.2004.840839.A moored array of current, temperature, conductivity,
and pressure sensors was deployed across the Chinese
continental shelf and slope in support of the Asian Seas International
Acoustics Experiment. The goal of the observations was to
quantify the water column variability in order to understand the
along- and across-shore low-frequency acoustic propagation in
shallow water. The moorings were deployed from April 21–May
19, 2001 and sampled at 1–5 min intervals to capture the full range
of temporal variability without aliasing the internal wave field.
The dominant oceanographic signal by far was in fact the highly
nonlinear internal waves (or solitons) which were generated near
the Batan Islands in the Luzon Strait and propagated 485 km
across deep water to the observation region. Dubbed trans-basin
waves, to distinguish them from other, smaller nonlinear waves
generated locally near the shelf break, these waves had amplitudes
ranging from 29 to greater than 140 m and were among the largest
such waves ever observed in the world’s oceans. The waves arrived
at the most offshore mooring in two clusters lasting 7–8 days each
separated by five days when no waves were observed.Within each
cluster, two types of waves arrived which have been named type-a
and type-b. The type-a waves had greater amplitude than the
type-b waves and arrived with remarkable regularity at the same
time each day, 24 h apart. The type-b waves were weaker than
the type-a waves, arrived an hour later each day, and generally
consisted of a single soliton growing out of the center of the
wave packet. Comparison with modeled barotropic tides from
the generation region revealed that: 1) The two clusters were
generated around the time of the spring tides in the Luzon strait;
and 2) The type-a waves were generated on the strong side of the
diurnal inequality while the type-b waves were generated on the
weaker beat. The position of the Kuroshio intrusion into the Luzon
Strait may modulate the strength of the waves being produced. As
the waves shoaled, the huge lead solitons first split into two solitons
then merged together into a broad region of thermocline depression
at depths less than 120 m. Elevation waves sprang up behind
them as they continued to propagate onshore. The elevation waves
also grew out of regions where the locally-generated internal tide
forced the main thermocline down near the bottom. The “critical point” where the upper and lower layers were equal was a good
indicator of when the depression or elevation waves would form,
however this was not a static point, but rather varied in both space
and time according to the presence or absence of the internal tides
and the incoming trans-basin waves themselves.The planning,
execution, and analysis of this work was supported by the U.S. Office of Naval
Research Ocean Acoustics and Physical Oceanography Programs. Significant
funding contributions were also made by the National Science Council of
Taiwan
Pleural Effusion after Percutaneous Radiofrequency Ablation for Hepatic Malignancies
AbstractBackground and AimsRadiofrequency ablation (RFA) can play an important role in the treatment of primary or metastatic liver tumors. Currently, percutaneous RFA is generally regarded as a safe, effective, and minimally invasive procedure. This study aimed to evaluate the presence and course of pleural effusion after monopolar RFA.MethodsFrom October 2008 to July 2013, a total of 54 patients (28 male and 26 female, mean age 65.2) treated with monopolar RFA were included in our study. 47 patients were diagnosed with hepatocellular carcinoma, 4 patients with hepatic metastasis, and 3 patients had other diagnoses. There were a total of 115 sessions of treatment and 199 liver tumors to be treated (1.73 ± 1.02 tumors treated per session). The tumor size ranged from 0.8 cm to 5.0 cm (mean 2.31 cm, standard deviation 1.04 cm). Thereafter, a follow-up ultrasound was performed within 24 hours subsequent to ablation to evaluate the presence of pleural effusion. The degree of pleural effusion was assessed by chest X-ray.ResultsFifteen (13.0%) treatment sessions in 14 patients showed right-sided pleural effusion after ablations. One patient had a large amount of effusion, while other patients manifested a minimal to small amount of effusion. There were 5 patients that experienced delayed resolution of pleural effusion; one patient (0.87%) had a minimal amount of pleural effusion even after one month. Overall, there was no pneumothorax, or periprocedural morality. Age, gender, tumor numbers, tumor sizes, and complete ablation of target tumors were similar among groups presenting with or without pleural effusion. Tumor locations associated with S78 segments abutting the diaphragm or right lobe of the liver were not associated with development of pleural effusion. Only the duration of ablation time had a marginal trend toward significance (p = 0.051).ConclusionsThe transient appearance of right-sided pleural effusion after percutaneous RFA for hepatic malignancies was not infrequent. However, refractory pleural effusion was rare
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