• Title/Summary/Keyword: maximal function

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Optimization of Mutual Information for Multiresolution Image Registration (다해상도 영상정합을 위한 상호정보 최적화)

  • Hong, Helen;Kim, Myoung-Hee
    • Journal of the Korea Computer Graphics Society
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    • v.7 no.1
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    • pp.37-49
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    • 2001
  • We propose an optimization of mutual information for multiresolution image registration to represent useful information as integrated form obtaining from complementary information of multi modality images. The method applies mutual information as cost function to measure the statistical dependency or information redundancy between the image intensities of corresponding pixels in both images, which is assumed to be maximal if the images are geometrically aligned. As experimental results we validate visual inspection for accuracy, changning initial condition and addictive noise for robustness. Since our method uses the native image rather than prior feature extraction, few user interaction is required to perform the registration. In addition it leads to robust density estimation and convergence as applying non-parametric density estimation and stochastic multiresolution optimization.

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Influence of Phellodendri Cortex Methanol Extract on the Responses of the Blood Pressure in the Rabbits and Cats (황백(黃柏) Methanol Extract의 가토(家兎) 및 가묘(家猫)의 혈압반응(血壓反應)에 미치는 영향(影響))

  • Lim, Dong-Yoon
    • Journal of Pharmaceutical Investigation
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    • v.9 no.3
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    • pp.27-38
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    • 1979
  • This study was attempted to investigate the pharmacological action, especially depressor action of Phellodendri cortex and to elucidate the mechanism of its action, making use of Phellodendri cortex methanol extract (PCME) because its hypotensive action is not clear. Influence of PCME on the blood pressure of the rabbits and cats were observed in this study. PCME, when given intravenously in the rabbits and cats, elicited the hypotensive action, but intraventricular PCME in the rabbits did not show depressor action. Accumulation and tachyphylaxis by PCME administered into the ear-vein of the rabbits were not shown. Depressor effect of PCME in the rabbits was attenuated significantly by pretreatment with phentolamine, guanethidine, chorisondamine and atropine, but not by propranolol, diphenhydramine, cyproheptadine and vagotomization. The pressor activity of angiotensin was unimpaired after injection of maximal hypotensive doses (100mg/kg) of PCME, but the pressor activity of norepinephrine and carotid occlusion was abolished markedly. In addition, PCME given into jugular vein of the cats weakened norepinephrine pressor responses and caused the reversal of epinephrine pressor responses. These results suggest that the hypotensive action of PCME may be due to dual mechanisms by interference with peripheral sympathetic function, alpha adrenoceptor blocking action, and peripheral parasympathomimetics action, muscarinic action.

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Effect of Long-term Step Exercise on the Cardiopulmonary Function and Blood Constituents (장기간의 계단운동 훈련이 심폐기능과 혈액화학상에 미치는 영향)

  • Hwang, Sang-Ik;Choe, Myoung-Ae;Koh, Chang-Soon
    • The Korean Journal of Physiology
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    • v.21 no.2
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    • pp.305-311
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    • 1987
  • To evaluate training effect, the step exercise was loaded to three mem for nine weeks. Step score, cardiopulmonary functions and blood constituents were measured before, during and after the test exercise (50 cm-step exercise and treadmill running), and were compared with the pre-tranining values. The results were as follows: 1) By the training, Harvard step score increased remarkably, expecially in the early stage of training. 2) The post-training values of maximal oxygen uptake increased very significantly and it seemed to be due to increases of stroke volume and tissue oxygen extraction. 3) After the training, the degree of increase in expired volume was small during the treadmill exercise. 4) By the training, increasing rate of respiratory quotient lessened during the exercise and it was considered to be caused by the decreases of carbohydrate consumption and anaerobic metabolism. 5) The blood cholesterol concentrations were harldy changed with this degree of training. 6) The blood lactate level decreased during the recovery periods and the values of the recovery 0 and 5 minutes decreased remarkably, in comparison with the pre-trained values. The above results suggest that the 9 week-training of the step exercise brings about the enhancement of circulatory functions and tissue oxygen utilization, and changes of food-stuffs used during the exercise.

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Characterization of a Lichenase Isolated from Soil Metagenome

  • Kim, Sang-Yoon;Oh, Doo-Byoung;Kwon, Ohsuk
    • Journal of Microbiology and Biotechnology
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    • v.24 no.12
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    • pp.1699-1706
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    • 2014
  • A lichenase gene (mt-lic) was identified for the first time through function-based screening of a soil metagenomic library. Its deduced amino acid sequence exhibited a high degree of homology with endo-${\beta}$-1,3-1,4-glucanase (having both lichenase and chitosanase activities), encoded by the bgc gene of Bacillus circulans WL-12. The recombinant lichenase overexpressed and purified from Escherichia coli was able to efficiently hydrolyze both barley ${\beta}$-glucan and lichenan. The enzyme showed maximal activity at a pH of 6.0 at $50^{\circ}C$, with Azo-barley-glucan as the substrate. The metal ions $Mn^{2+}$, $Mg^{2+}$, $Ca^{2+}$, and $Fe^{2+}$ enhanced the enzymatic activity, whereas the $Cu^{2+}$ and $Zn^{2+}$ ions inhibited the enzymatic activity. The $K_m$ and $V_{max}$ values of the purified lichenase were determined to be 0.45 mg/ml and 24.83 U/min/mg of protein, respectively.

Magnetic Resonance Imaging as a Biomarker for Duchenne Muscular Dystrophy

  • Lim, Woo-taek
    • Physical Therapy Korea
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    • v.22 no.3
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    • pp.98-105
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    • 2015
  • Muscular dystrophy is a hereditary musculoskeletal disorder caused by a mutation in the dystrophin gene. Duchenne muscular dystrophy (DMD) is one of the most common, and progresses relatively faster than other muscular dystrophies. It is characterized by progressive myofiber degeneration, muscle weakness and ultimately ambulatory loss. Since it is an X-linked recessive inheritance, DMD is mostly expressed in males and rarely expressed or less severe in females. The most effective measurement tool for DMD is magnetic resonance imaging (MRI), which allows non-invasive examination of longitudinal measurement. It can detect progressive decline of skeletal muscle size by measuring a maximal cross-sectional area of skeletal muscle. Additionally, other techniques in MRI, like $T_2$-weighted imaging, assess muscle damage, including inflammation, by detecting changes in $T_2$ relaxation time. Current MRI techniques even allow quantification of metabolic differences between affected and non-affected muscles in DMD. There is no current cure, but physical therapist can improve their quality of life by maintaining muscle strength and function, especially if treatment (and other forms of medical intervention) begins in the early stages of the disease.

Effect of Si:C Ratio on Porosity and Flexural Strength of Porous Self-Bonded Silicon Carbide Ceramics (Si:C Ratio가 다공질 Self-Bonded SiC 세라믹스의 기공율과 곡강도에 미치는 영향)

  • Lim, Kwang-Young;Kim, Young-Wook;Woo, Sang-Kuk;Han, In-Sub
    • Journal of the Korean Ceramic Society
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    • v.45 no.5
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    • pp.285-289
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    • 2008
  • Porous self-bonded silicon carbide (SiC) ceramics were fabricated at temperatures ranging from 1750 to $1850^{\circ}C$ using SiC, silicon (Si), and carbon (C) powders as starting materials. The effect of the Si:C ratio on porosity and strength was investigated as a function of sintering temperature. It was possible to produce self-bonded SiC ceramics with porosities ranging from 36% to 43%. The porous ceramics showed a maximal porosity when the Si:C ratio was 2:1 regardless of the sintering temperature. In contrast, the maximum strength was obtained when the ratio was 5:1.

Structure and Dielectric properties of PST Thin Films with Pb/Sr ratio prepared by Sol-gel method for Phase shifter (Phase shifters 응용을 위한 Sol-gel 법으로 제작된 PST 박막의 Pb/Sr 비에 따른 구조적, 유전적 특성)

  • Lee, Cheol-In;Kim, Kyoung-Tae;Kim, Chang-Il
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07b
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    • pp.794-797
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    • 2004
  • The object of investigation is represented by PbxSrl-xTiO3(PST) thin films, which were fabricated by the alkoxide-based sol-gel method on Pt/Ti/SiO2/Si substrate. We have investigated both structural and dielectric properties of PST thin films aimed to tunable microwave device applications as a function of Pb/Sr ratio. PST thin films showedtypical polycrystalline structure with a dense microstructure without secondary phase formation. Dielectric properties of PST films were found as strongly dependent on Pb/Sr composition ratio. Increasing of Pb content leads to simultaneous increasing of both dielectric constant and dielectric loss characteristics of PST films. The figure of merit (FOM) Parameter (FOM : (%) tunability / tan (%)) reached a maximal value of 27.5 corresponding to Pb/Sr ratio of 40/60. The tunability increased with increasing Pb content. The dielectric constants, dielectric loss and tunability of the PST thin films at Pb/sr ratio of 40/60 measured at 100 kHz were 335, 0.0174 and 47.89 %, respectively.

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$^{131}I$-O-Iodohippurate Renogram in Epidemic Hemorrhagic Fever (유행성(流行性) 출혈열환자(出血熱患者)의 Radio Renogram)

  • Kim, Myung-Jae
    • The Korean Journal of Nuclear Medicine
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    • v.1 no.2
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    • pp.75-84
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    • 1967
  • $^{131}I$-labeled-O-iodohippurate renograms in 15 cases of epidemic hemorrhagic fever(E.H. fever)during oliguric, diuretic and convalescent phase were analysed quantitatively and qualitatively, namely by its configuration, Tmax T 1/2 and renal index of Hirakawa. The results were as following: 1) Changes on the renograms in E.H. fever showed simultaneous bilateral renal impairment. 2) The characteristic configurations of renogram in the oliguric phase were: (1) Moderately decreased absolute amplitude of initial spike. (2) Continous rising second slope. (3) No appearance of terminal descent. Those were mast likely to those of renograms in acute ureteral obstruction or acute dehydration state. 3) During the diuretic phase, the renogram showed the point of maximal amplitude, but the steepness of 2nd slope was markedly decreased. The appearance of terminal descents was observed with unusually high amplitude despite of the tremendously large amount of urinary output during this phase. 4) In convalescence, the renograms were essentially normal in configuration, but the renal index of Hirakawa was not recovered until this phase. 5) Renograms in E.H. fever showed the characteristic patterns in each phase of its clinical course. 6) $^{131}I$-OIH-Renogram might be an useful method for the evaluation of renal function in E.H. fever during its course.

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Pharmacodynamics of Potassium Channel Opener Lemakalim in the Isolated Rat Hearts and Conscious SHRs under Hyperkalemic and Hypokalemic Condition (칼륨채널 활성물질 Lemakalim의 고칼륨혈증 및 저칼륨혈증에서의 심기능에 대한 영향 및 항 고혈압작용)

  • 신홍섭;신화섭;권광일
    • YAKHAK HOEJI
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    • v.37 no.5
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    • pp.463-475
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    • 1993
  • Pharmacological effects of lemakalim on cardiovascular system were investigated using isolated rat hearts and conscious SHRs subjected to hyperkalemic and hypokalemic condition. In the isolated hearts perfused with normal physiological salt solution(4.7 mM KCI), lemakalim increased cardiac function and coronary flow, and these effects were significantly potentiated under hypokalemic(1.2, 2.5 mM KCI), but attenuated under hyperkalemic(IO mM KCI) condition. In conscious SHRS, lemakalim(0.1, 0.2, 0.3mg/kg, p.o.) produced a dose-related decrease in systolic blood pressure, the maximal hypotensive effect being reached around 0.5 hr after dosing. The intensity and the duration of hypotensive effect of lemakalim were significantly increased when administered in combination with dihydrochlorothiazide (2 mg/kg, p.o.), but decreased with triamterene(32 mg/kg, p.o.). It appears that the differential effects of two types of diuretics on the hypotensive action of lemakalim are due to their hypokalemic and hyperkalemic action, respectively. It is conclued that the concomitant use of $K^{+}$ channel openers and hypokalemic diuretics may be an appropriate model of combination therapy in the treatment of hypertension.

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Non-chemical Risk Assessment for Lifting and Low Back Pain Based on Bayesian Threshold Models

  • Pandalai, Sudha P.;Wheeler, Matthew W.;Lu, Ming-Lun
    • Safety and Health at Work
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    • v.8 no.2
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    • pp.206-211
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    • 2017
  • Background: Self-reported low back pain (LBP) has been evaluated in relation to material handling lifting tasks, but little research has focused on relating quantifiable stressors to LBP at the individual level. The National Institute for Occupational Safety and Health (NIOSH) Composite Lifting Index (CLI) has been used to quantify stressors for lifting tasks. A chemical exposure can be readily used as an exposure metric or stressor for chemical risk assessment (RA). Defining and quantifying lifting nonchemical stressors and related adverse responses is more difficult. Stressor-response models appropriate for CLI and LBP associations do not easily fit in common chemical RA modeling techniques (e.g., Benchmark Dose methods), so different approaches were tried. Methods: This work used prospective data from 138 manufacturing workers to consider the linkage of the occupational stressor of material lifting to LBP. The final model used a Bayesian random threshold approach to estimate the probability of an increase in LBP as a threshold step function. Results: Using maximal and mean CLI values, a significant increase in the probability of LBP for values above 1.5 was found. Conclusion: A risk of LBP associated with CLI values > 1.5 existed in this worker population. The relevance for other populations requires further study.