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Search Results: 1 - 10 of 362195 matches for " Christopher K. C. Lee "
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Multifractal Measures on Small-World Networks
Kyungsik Kim,K. H. Chang,S. M. Yoon,C. Christopher Lee,J. S. Choi
Physics , 2004,
Abstract: We investigate the multifractals of the normalized first passage time on one-dimensional small-world network with both reflecting and absorbing barriers. The multifractals is estimated from the distribution of the normalized first passage time charactrized by the random walk on the small-world network with three fractions of edges rewired randomly. Particularly, our estimate is the fractal dimension D_0 = 0.917, 0.926, 0.930 for lattice points L = 80 and a randomly rewired fraction p = 0.2. The numerical result is found to disappear multifractal properties in the regime p> p_c, where p_c is the critical rewired fraction.
Zipf's Law Distributions for Korean Stock Prices
Kyungsik Kim,S. -M. Yoon,C. Christopher Lee,K. H. Chang
Quantitative Finance , 2004,
Abstract: This paper investigates the rank distribution, cumulative probability, and probability density of price returns for the stocks traded in the KSE and the KOSDAQ market. This research demonstrates that the rank distribution is consistent approximately with the Zipf's law with exponent $\alpha = -1.00$ (KSE) and -1.31 (KOSDAQ), similar that of stock prices traded on the TSE. In addition, the cumulative probability distribution follows a power law with scaling exponent $\beta = -1.23$ (KSE) and -1.45 (KOSDAQ). In particular, the evidence displays that the probability density of normalized price returns for two kinds of assets almost has the form of an exponential function, similar to the result in the TSE and the NYSE.
Landscape Epidemiology and Control of Pathogens with Cryptic and Long-Distance Dispersal: Sudden Oak Death in Northern Californian Forests
Jo?o A. N. Filipe ,Richard C. Cobb,Ross K. Meentemeyer,Christopher A. Lee,Yana S. Valachovic,Alex R. Cook,David M. Rizzo,Christopher A. Gilligan
PLOS Computational Biology , 2012, DOI: 10.1371/journal.pcbi.1002328
Abstract: Exotic pathogens and pests threaten ecosystem service, biodiversity, and crop security globally. If an invasive agent can disperse asymptomatically over long distances, multiple spatial and temporal scales interplay, making identification of effective strategies to regulate, monitor, and control disease extremely difficult. The management of outbreaks is also challenged by limited data on the actual area infested and the dynamics of spatial spread, due to financial, technological, or social constraints. We examine principles of landscape epidemiology important in designing policy to prevent or slow invasion by such organisms, and use Phytophthora ramorum, the cause of sudden oak death, to illustrate how shortfalls in their understanding can render management applications inappropriate. This pathogen has invaded forests in coastal California, USA, and an isolated but fast-growing epidemic focus in northern California (Humboldt County) has the potential for extensive spread. The risk of spread is enhanced by the pathogen's generalist nature and survival. Additionally, the extent of cryptic infection is unknown due to limited surveying resources and access to private land. Here, we use an epidemiological model for transmission in heterogeneous landscapes and Bayesian Markov-chain-Monte-Carlo inference to estimate dispersal and life-cycle parameters of P. ramorum and forecast the distribution of infection and speed of the epidemic front in Humboldt County. We assess the viability of management options for containing the pathogen's northern spread and local impacts. Implementing a stand-alone host-free “barrier” had limited efficacy due to long-distance dispersal, but combining curative with preventive treatments ahead of the front reduced local damage and contained spread. While the large size of this focus makes effective control expensive, early synchronous treatment in newly-identified disease foci should be more cost-effective. We show how the successful management of forest ecosystems depends on estimating the spatial scales of invasion and treatment of pathogens and pests with cryptic long-distance dispersal.
Feasibility of Multiple Repeat Gamma Knife Radiosurgeries for Trigeminal Neuralgia: A Case Report and Review of the Literature
Guy C. Jones,Ameer L. Elaimy,John J. Demakas,Hansi Jiang,Wayne T. Lamoreaux,Robert K. Fairbanks,Alexander R. Mackay,Barton S. Cooke,Christopher M. Lee
Case Reports in Medicine , 2011, DOI: 10.1155/2011/258910
Abstract: Treatment options for trigeminal neuralgia (TN) must be customized for the individual patient, and physicians must be aware of the medical, surgical, and radiation treatment modalities to prescribe optimal treatment courses for specific patients. The following case illustrates the potential for gamma knife radiosurgery (GKRS) to be repeated multiple times for the purpose of achieving facial pain control in cases of TN that have been refractory to other medical and surgical options, as well as prior GKRS. The patient described failed to achieve pain control with initial GKRS, as well as medical and surgical treatments, but experienced significant pain relief for a period of time with a second GKRS procedure and later underwent a third procedure. Only a small subset of patients have reportedly undergone more than two GKRS for TN; thus, further research and long-term clinical followup will be valuable in determining its usefulness in specific clinical situations.
Olfactory Neuroblastoma Treated by Endoscopic Surgery Followed by Combined External Beam Radiation and Gamma Knife for Optic Nerve and Chiasm Sparing: A Case Report
Hansi Z. Jiang,Ameer L. Elaimy,Guy C. Jones,Alexander R. Mackay,Robert K. Fairbanks,Wayne T. Lamoreaux,John J. Demakas,Barton S. Cooke,Christopher M. Lee
Case Reports in Medicine , 2011, DOI: 10.1155/2011/765645
Abstract: We describe the multimodality treatment regimen of a 53-year-old man diagnosed with olfactory neuroblastoma (Kadish stage C) in the right nasal cavity extending into the ethmoid sinus and across the cribriform plate. Endoscopic surgery for tumor resection was followed by a combination of external beam radiotherapy and stereotactic radiosurgery boost with concurrent chemotherapy. The novel combination of dual radiation therapies allowed for the preservation of the nearby optic structures while providing an adequate dosage to a sufficient volume of the afflicted tissue.
Illuminating the Capabilities of the Suomi National Polar-Orbiting Partnership (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band
Steven D. Miller,William Straka,Stephen P. Mills,Christopher D. Elvidge,Thomas F. Lee,Jeremy Solbrig,Andi Walther,Andrew K. Heidinger,Stephanie C. Weiss
Remote Sensing , 2013, DOI: 10.3390/rs5126717
Abstract: Daytime measurements of reflected sunlight in the visible spectrum have been a staple of Earth-viewing radiometers since the advent of the environmental satellite platform. At night, these same optical-spectrum sensors have traditionally been limited to thermal infrared emission, which contains relatively poor information content for many important weather and climate parameters. These deficiencies have limited our ability to characterize the full diurnal behavior and processes of parameters relevant to improved monitoring, understanding and modeling of weather and climate processes. Visible-spectrum light information does exist during the nighttime hours, originating from a wide variety of sources, but its detection requires specialized technology. Such measurements have existed, in a limited way, on USA Department of Defense satellites, but the Suomi National Polar-orbiting Partnership (NPP) satellite, which carries a new Day/Night Band (DNB) radiometer, offers the first quantitative measurements of nocturnal visible and near-infrared light. Here, we demonstrate the expanded potential for nocturnal low-light visible applications enabled by the DNB. Via a combination of terrestrial and extraterrestrial light sources, such observations are always available—expanding many current existing applications while enabling entirely new capabilities. These novel low-light measurements open doors to a wealth of new interdisciplinary research topics while lighting a pathway toward the optimized design of follow-on satellite based low light visible sensors.
Allelic Variation on Murine Chromosome 11 Modifies Host Inflammatory Responses and Resistance to Bacillus anthracis
Jill K. Terra,Bryan France,Christopher K. Cote,Amy Jenkins,Joel A. Bozue,Susan L. Welkos,Ragini Bhargava,Chi-Lee Ho,Margarete Mehrabian,Calvin Pan,Aldons J. Lusis,Richard C. Davis,Steven M. LeVine,Kenneth A. Bradley
PLOS Pathogens , 2011, DOI: 10.1371/journal.ppat.1002469
Abstract: Anthrax is a potentially fatal disease resulting from infection with Bacillus anthracis. The outcome of infection is influenced by pathogen-encoded virulence factors such as lethal toxin (LT), as well as by genetic variation within the host. To identify host genes controlling susceptibility to anthrax, a library of congenic mice consisting of strains with homozygous chromosomal segments from the LT-responsive CAST/Ei strain introgressed on a LT-resistant C57BL/6 (B6) background was screened for response to LT. Three congenic strains containing CAST/Ei regions of chromosome 11 were identified that displayed a rapid inflammatory response to LT similar to, but more severe than that driven by a LT-responsive allele of the inflammasome constituent NRLP1B. Importantly, increased response to LT in congenic mice correlated with greater resistance to infection by the Sterne strain of B. anthracis. The genomic region controlling the inflammatory response to LT was mapped to 66.36–74.67 Mb on chromosome 11, a region that encodes the LT-responsive CAST/Ei allele of Nlrp1b. However, known downstream effects of NLRP1B activation, including macrophage pyroptosis, cytokine release, and leukocyte infiltration could not fully explain the response to LT or the resistance to B. anthracis Sterne in congenic mice. Further, the exacerbated response in congenic mice is inherited in a recessive manner while the Nlrp1b-mediated response to LT is dominant. Finally, congenic mice displayed increased responsiveness in a model of sepsis compared with B6 mice. In total, these data suggest that allelic variation of one or more chromosome 11 genes in addition to Nlrp1b controls the severity of host response to multiple inflammatory stimuli and contributes to resistance to B. anthracis Sterne. Expression quantitative trait locus analysis revealed 25 genes within this region as high priority candidates for contributing to the host response to LT.
Local Binary Patterns and Its Variants for Finger Knuckle Print Recognition in Multi-Resolution Domain  [PDF]
D. R. Arun, C. Christopher Columbus, K. Meena
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.710267
Abstract: Finger Knuckle Print biometric plays a vital role in establishing security for real-time environments. The success of human authentication depends on high speed and accuracy. This paper proposed an integrated approach of personal authentication using texture based Finger Knuckle Print (FKP) recognition in multiresolution domain. FKP images are rich in texture patterns. Recently, many texture patterns are proposed for biometric feature extraction. Hence, it is essential to review whether Local Binary Patterns or its variants perform well for FKP recognition. In this paper, Local Directional Pattern (LDP), Local Derivative Ternary Pattern (LDTP) and Local Texture Description Framework based Modified Local Directional Pattern (LTDF_MLDN) based feature extraction in multiresolution domain are experimented with Nearest Neighbor and Extreme Learning Machine (ELM) Classifier for FKP recognition. Experiments were conducted on PolYU database. The result shows that LDTP in Contourlet domain achieves a promising performance. It also proves that Soft classifier performs better than the hard classifier.
Temporal changes of sleep disturbances and their associations with CYP450 2B6 polymorphism and plasma drug level in HIV patients on efavirenz
K To,M Lee,C Lee,S Lee
Journal of the International AIDS Society , 2012, DOI: 10.7448/ias.15.6.18327
Abstract: Neurological and sleep disturbances were commonly reported among HIV patients on efavirenz (EFV), the pharmacokinetic pattern varies with different CYP450 2B6 G516T genotypes. This prospective study aims to detect temporal changes and differences in the profile of these adverse reactions and their relation to plasma EFV level and host genotypes. HIV patients of Chinese ethnicity on an EFV-containing HAART regimen were recruited from a specialist clinic. Blood for CYP2B6 G516T genotypes was taken. A questionnaire assessing adverse neurological problems and sleep disturbance was administered, alongside testing for plasma EFV levels at baseline, 4 weeks, 8 months and 1 year intervals after treatment. Analysis was performed using χ2 and t-test. A total of 64 patients (31 GG, 27 GT, 6 TT genotypes, 59 male, and 5 female, mean age of 41±9.9) were recruited. At 4 weeks after EFV, 49 (76%) gave a history of any one of the neurological side effects: dizziness, headache and drunk feeling. Sleep disturbances were common: bizarre dream (45%), nightmares (35%), waking at night (73%), poor sleep quality (31%), nocturia (84%) and difficulty in falling asleep (67%). The mean plasma EFV level of GG genotype was 2.8 μg/ml and 3 μg/ml, GT genotype was 3.8 μg/ml and 3.9 μg/ml, at 4 weeks and 1 year respectively. The mean plasma EFV level of TT genotype was 11.9 μg/ml and 9.7 μg/ml at 4 weeks and 1 year respectively. There was no significant variation of drug level within each genotype over time (p>0.08), while EFV level of TT was significantly higher at all time points (p<0.01). Overall, nightmares and difficulty to fall asleep were significantly related to the plasma EFV level (p=0.021 and 0.017 respectively). However, the sleep quality, nocturnal awakening, nocturia or requirement of sleeping pills was not significantly associated with EFV level (p=0.28, 0.06, 0.1 and 0.5 respectively). When the side effects were separately evaluated according to time points, they all became insignificantly related to plasma EFV level at 12 weeks. In conclusion, very high plasma EFV level was observed in TT genotype (9.4% of patients). There was no relationship between genotype GG/GT and the occurrence of neurological side effects. While selected sleep disturbances like nightmares and difficulty to fall asleep were associated with plasma EFV levels, the general sleep quality was not significantly affected. The influence of plasma EFV levels on side effects diminished over time.
Role of Turbulent Heat Fluxes over Land in the Monsoon over East Asia  [PDF]
Eungul Lee, Carol C. Barford, Christopher J. Kucharik, Benjamin S. Felzer, Jonathan A. Foley
International Journal of Geosciences (IJG) , 2011, DOI: 10.4236/ijg.2011.24046
Abstract: Atmospheric heat and moisture over land are fundamental drivers of monsoon circulations. However, these drivers are less frequently considered in explaining the development and overall intensity of monsoons than heat and moisture over the ocean. In this study, the roles of turbulent heat fluxes over land in the monsoon system over East Asia are examined using Climatic Research Unit observations and European Centre for Medium-Range Weather Forecasts reanalysis, and they are further explored using simulated sensible (H) and latent (LE) heat fluxes from an ecosystem model (Predicting Ecosystem Goods and Services Using Scenarios or PEGASUS). Changes in the H fluxes over the land during the pre-monsoon season (March-May: MAM) affect the differential heating between land and ocean, which in turn controls monsoon development. In July, an intensified contrast of the mean sea level pressure between land and ocean is observed during the years of stronger land-sea H contrast in MAM, which results in enhanced onshore flows and more rainfall over southern East Asia. After monsoon onset, the contrast of H is influenced by monsoon rainfall through the cooling effect of precipitation on surface air temperature. During the monsoon season (June-September: JJAS), LE fluxes are more important than H fluxes, since LE fluxes over land and ocean affect overall monsoon intensity through changes in the land-sea contrast of turbulent heat fluxes. Significantly increased monsoon rainfall over western East Asia is observed during the years of larger LE over the land in JJAS. In ecosystem modeling, we find that the monsoon can be weakened as potential (natural) vegetation is converted to bare ground or irrigated cropland. Simulated H fluxes in MAM and LE fluxes in JJAS over the land significantly decrease in irrigated crop and bare ground scenarios, respectively, which play crucial roles in controlling monsoon development and overall intensity.
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