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Wavelet denoising via sparse representation

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Science in China(Series F) 2009年第8期52卷 1371-1377页

作者： ZHAO RuiZhen LIU XiaoYu Ching-Chung LI Robert J. SCLABASSI & SUN MinGui institute of Information Science Beijing Jiaotong University Beijing 100044 China Department of Neurosurgery University of Pittsburgh Pittsburgh PA 15261 USA Department of Electrical & Computer Engineering University of Pittsburgh Pittsburgh PA 15261 USA

Wavelet threshold denoising is a powerful method for suppressing noise in signals and images. However, this method often uses a coordinate-wise processing scheme, which ignores the structural properties in the wavelet coefficients. We propose a new wavelet denoising method using sparse representation which is a powerful mathematical tool recently developed. Instead of thresholding wavelet coefficients individually, we minimize the number of non-zero coefficients under certain conditions. The denoised signal is reconstructed by solving an optimization problem. It is shown that the solution to the optimization problem can be obtained uniquely and the estimates of the denoised wavelet coefficients are unbiased, i.e., the statistical means of the estimates are equal to the noise-free wavelet coefficients. It is also shown that at least a local optimal solution to the denoising problem can be found. Our experiments on test data indicate that this new denoising method is effective and efficient for a wide variety of signals including those with low signal-to-noise ratios.

关键词： signal processing denoising sparse representation wavelet transform

Excitotoxicity, calcium and mitochondria: a triad in synaptic neurodegeneration

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Translational Neurodegeneration 2022年第1期11卷 917-930页

作者： Manish Verma Britney N.Lizama Charleen T.Chu Department of Pathology University of Pittsburgh School of MedicinePittsburghPA 15261USA Department of Ophthalmology University of Pittsburgh School of MedicinePittsburghPA 15261USA pittsburgh institute for Neurodegenerative Diseases University of Pittsburgh School of MedicinePittsburghPA 15261USA McGowan institute for Regenerative Medicine University of Pittsburgh School of MedicinePittsburghPA 15261USA Center for Protein Conformational Diseases University of PittsburghPittsburghPA 15261USA Center for Neuroscience University of PittsburghPittsburghPA 15261USA Present Address:Astellas Pharma Inc. 9 Technology DriveWestboroughMA 01581USA.

Glutamate is the most commonly engaged neurotransmitter in the mammalian central nervous system,acting to mediate excitatory ***,high levels of glutamatergic input elicit excitotoxicity,contribut-ing to neuronal cell death following acute brain injuries such as stroke and *** excitotoxic cell death has also been implicated in some neurodegenerative disease models,the role of acute apoptotic cell death remains controversial in the setting of chronic ***,it is clear that excitatory synaptic dysregula-tion contributes to neurodegeneration,as evidenced by protective effects of partial N-methyl-D-aspartate receptor ***,we review evidence for sublethal excitatory injuries in relation to neurodegeneration associated with Parkinson’s disease,Alzheimer’s disease,amyotrophic lateral sclerosis and Huntington’s *** contrast to classic excitotoxicity,emerging evidence implicates dysregulation of mitochondrial calcium handling in excitatory post-synaptic *** discuss mechanisms that regulate mitochondrial calcium uptake and release,the impact of LRRK2,PINK1,Parkin,beta-amyloid and glucocerebrosidase on mitochondrial calcium transporters,and the role of autophagic mitochondrial loss in axodendritic ***,we discuss strategies for normalizing the flux of calcium into and out of the mitochondrial matrix,thereby preventing mitochondrial calcium toxicity and excitotoxic dendritic *** the mechanisms that underlie increased uptake or decreased release of mitochondrial calcium vary in different model systems,a common set of strategies to normalize mitochondrial calcium flux can prevent excitatory mitochondrial toxicity and may be neuroprotective in multiple disease contexts.

关键词： Mitochondrial calcium Mitochondrial calcium uniporter NCLX antiporter Parkinson’s disease Alzheimer’s disease LRRK2 PINK1 Beta-amyloid Mitophagy Excitotoxicity Amyotrophic lateral sclerosis Huntington’s disease Glucocerebrosidase

Old vs new: Risk factors predicting early onset colorectal cancer

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World Journal of Gastrointestinal Oncology 2019年第11期11卷 1011-1020页

作者： Aslam R Syed Payal Thakkar Zachary D Horne Heitham Abdul-Baki Gursimran Kochhar Katie Farah Shyam Thakkar Division of Gastroenterology Allegheny Health NetworkPittsburghPA 15212United States Allegheny Singer Research institute Allegheny Health NetworkPittsburghPA 15212United States Division of Radiation Oncology Allegheny Health Network Cancer InstitutePittsburghPA 15212United States

BACKGROUND Colorectal cancer(CRC)is the second leading cause of all cancer related deaths in the United States and *** the incidence has been decreasing for individuals’≥50,it has been on the rise for individualscancer(OR 1.78,95%CI:1.67-1.90,P<0.001),gastrointestinal(GI)malignancy(OR 2.36,95%CI:2.18-2.55,P<0.001),polyps(OR 1.41,95%CI:1.08-1.20,P<0.001),and obesity(OR 1.14,95%CI:1.08-1.20,P<0.001).Comparing the early-onset cohort versus the control group,factors that were associated with an increased risk of CRC were:male gender(OR 1.34,95%CI:1.27-1.41),P<0.001),Caucasian(OR 1.48,95%CI:1.40-1.57,P<0.001)and African-American race(OR 1

关键词： Colorectal cancer Early-onset colorectal cancer Colorectal cancer screening Epidemiology analysis Colorectal neoplasm Average-risk screening

Assessing support alternatives for longwall gateroads subject to changing stress

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International Journal of Mining Science and Technology 2021年第1期31卷 103-110页

作者： Gabriel S.Esterhuizen I.Berk Tulu Dave F.Gearhart Heather Dougherty Mark Van Dyke National institute for Occupational Safety and Health Pittsburgh Mining Research DivisionPittsburghPA 15236USA West Virginia university MorgantownWV 26506USA

Longwall gateroad entries are subject to changing horizontal and vertical stress induced by redistribution of loads around the extracted *** stress changes can result in significant deformation of the entries that may include roof sag,rib dilation,and floor *** operators install different types of supports to control the ground response and maintain safe access and ventilation of the longwall *** paper describes recent research aimed at quantifying the effect of longwall-induced stress changes on ground stability and using the information to assess support *** research included monitoring of ground and support interaction at several operating longwall mines in the U.S.,analysis and calibration of numerical models that adequately represent the bedded rock mass,and observation of the support systems and their response to changes in *** models were then used to investigate the impact of geology and stress conditions on ground deformation and support response for various depths of cover and geologic *** research results were summarized in two regression equations that can be used to estimate the likely roof deformation and height of roof yield due to longwall-induced stress *** information is then used to assess the ability of support systems to maintain the stability of the *** application of the method is demonstrated with a retrospective analysis of the support performance at an operating longwall mine that experienced a headgate roof *** method is shown to produce realistic estimates of gateroad entry stability and support performance,allowing alternative support systems to be assessed during the design and planning stage of longwall operations.

关键词： Longwall Gateroad Support design Coal Standing support

FORMATION OF SINGULARITY FOR COMPRESSIBLE VISCOELASTICITY

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Acta Mathematica Scientia 2012年第1期32卷 109-128页

作者： Xianpeng Hu Dehua Wang Courant institute of Mathematical Sciences New York University New York NY 10012 USA Department of Mathematics University of Pittsburgh Pittsburgh PA 15260 USA

The formation of singularity and breakdown of classical solutions to the three- dimensional compressible viscoelasticity and inviscid elasticity are considered. For the compressible inviscid elastic fluids, the finite-time formation of singularity in classical solu- tions is proved for certain initial data. For the compressible viscoelastic fluids, a criterion in term of the temporal integral of the velocity gradient is obtained for the breakdown of smooth solutions.

关键词： compressible viscoelastic fluid inviscid elasticity local classical solution formation of singularity blowup breakdown

Bleeder entry evaluation using condition mapping and numerical modeling

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International Journal of Mining Science and Technology 2021年第1期31卷 137-143页

作者： Ted M.Klemetti Mark A.Van Dyke Gabriel S.Esterhuizen National institute for Occupational Safety and Health Pittsburgh Mining Research DivisionPittsburghPA 15236USA

One of the most common critical areas of longwall mining in terms of ground stability are the gateroad and bleeder *** critical entries provide much-needed safe access for miners and allow for adequate ventilation required for dilution of hazardous airborne contaminants and must remain open during mining of a multi-panel *** paper is focused on the stability of the longwall entries subjected to a single abutment load such as bleeders,first tailgate,and last *** tailgate and last headgate are also referred to as blind headgate and tailgate.A study of a longwall district through conditions mapping,support evaluations,and numerical modeling was conducted and evaluated by researchers from the National institute for Occupational Safety and Health(NIOSH).The condition mapping and support evaluations were performed on entries that spanned the previous five years of mining and relied on a diverse selection of supports to maintain the functionality of the *** modeling was also conducted to evaluate various support types with further investigation and comparison to the condition *** study demonstrated the importance of the abutment load decay versus distance from the gob edge,the potential for a reduction in material handling related injuries,as well as optimal usage of secondary and standing support.

关键词： Stability assessment Bleeder entry Abutment loading Condition mapping Longwall Ground control

Coal mine entry rating system:A case study

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International Journal of Mining Science and Technology 2021年第1期31卷 145-151页

作者： Mark A.Van Dyke Ted M.Klemetti Craig Compton National institute for Occupational Safety and Health Pittsburgh Mining Research DivisionPittsburghPA 15236USA

Coal mines are continuously seeking to determine the performance of entries with different ground control products and installation *** are many factors that impact how an entry will perform which include but are not limited to geology,overburden,bolting type and pattern,and mine *** the National institute for Occupational Safety and Health(NIOSH),research has been instituted to examine the relationship of the parts of a coal mine entry as a system and not as individual *** study this relationship,the first step in this study was to create a numeric rating system that accurately reflects visual observations of the mine entry and is easy to *** researchers devised this rating system to improve upon previous ideas,offering increased flexibility which can be incorporated into an overall entry condition that offers different levels of confidence based on the user’s time devoted to the *** new entry rating system was implemented at three different mines over varying periods of time to evaluate the ground response to the geology,bolt installation pattern,stress changes by mining,overburden,and time dependency.

关键词： Coal Geology Rating system Support

Preliminary rib support requirements for solid coal ribs using a coal pillar rib rating(CPRR)

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International Journal of Mining Science and Technology 2021年第1期31卷 15-22页

作者： Khaled Mohamed Mark Van Dyke Gamal Rashed Morgan MSears Robert Kimutis National institute for Occupational Safety and Health Pittsburgh Mining Research DivisionPittsburghPA 15236USA

Researchers from the National institute for Occupational Safety and Health(NIOSH)are developing a coal pillar rib rating(CPRR)technique to measure the integrity of coal *** CPRR characterizes the rib composition and evaluates its impact on the inherent stability of the coal *** CPRR utilizes four parameters:rib homogeneity,bedding condition,face cleat orientation with respect to entry direction,and rib *** these parameters are measurable in the field.A rib data collecting procedure and a simple sheet to calculate the CPRR were *** developed CPRR can be used as a rib quality mapping tool in underground coal mines and to determine the potential of local rib instabilities and support requirements associated with overburden *** calculations were conducted for 22 surveyed solid coal ribs,mainly composed of coal *** on this study,the rib performance was classified into four categories.A preliminary minimum primary rib support density(PRSD)line was obtained from these surveyed *** sample cases are presented that illustrate the data collection form and CPRR calculations.

关键词： Coal rib stability Rib support design Coal pillar rib rating Rib quality mapping CPRR Coal classification

Liver retransplants using living donors:An approach for management

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Liver Research 2023年第3期7卷 252-255页

作者： Hasan Al Harakeh Christopher Hughes Amit Tevar Vikram Gunabushanam Eishan Ashwat Hao Liu Abhinav Humar Starzl Transplantation institute University of Pittsburgh Medical CenterPittsburghPAUSA

Background and aims:Many centers do not offer living donor transplants for patients in need of a liver *** aimed to study our liver retransplant outcomes using living donors and compared them with those of retransplants performed using deceased ***:This study retrospectively analyzed all retransplants performed at our center between 2009 and 2023,and outcomes of living donor retransplants were compared with deceased donor retransplants using standard statistical ***:Between January 2009 and March 2023,a total of 77 retransplants,60 with deceased donors and 17 with living donors,were *** demographic differences between the two groups included a higher model for end-stage liver disease score in the deceased donor group(32.1±6.1 vs.19.4±5.7,P<0.001)and a higher number of early retransplants(within 3 months of the initial transplant),which accounted for 35% of deceased donor transplants but 0 of living donor transplants(P<0.01).Overall,the patient and graft survival rates were comparable between the two *** patient survival rates at 1 and 3 years after transplant were 73% and 67% in the deceased donor group and 84% and 73% in the living donor group,respectively(P=0.57).The hospital length of stay and blood product use were both better in the living donor *** complications did not show significant different between the two groups(P=0.33).Conclusions:Living donors can provide acceptable outcomes for those in need of a retransplant,with results comparable to those seen with deceased donors.A systematic approach to the patient in the pre-,peri-,and post-transplantation period is important in these complicated cases.

关键词： Liver retransplant Living donor liver transplant Deceased donor Outcomes Complications