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Articles 1 - 17 of 17
Full-Text Articles in Mathematics
Correlation Properties Of Collective Motion In Bacterial Suspensions, Shawn D. Ryan, Andrey Sokolov, Leonid Berlyand, Igor S. Aranson
Correlation Properties Of Collective Motion In Bacterial Suspensions, Shawn D. Ryan, Andrey Sokolov, Leonid Berlyand, Igor S. Aranson
Mathematics and Statistics Faculty Publications
The study of collective motion in bacterial suspensions has been of significant recent interest. To better understand the non-trivial spatio-temporal correlations emerging in the course of collective swimming in suspensions of motile bacteria, a simple model is employed: a bacterium is represented as a force dipole with size, through the use of a short-range repelling potential, and shape. The model emphasizes two fundamental mechanisms: dipolar hydrodynamic interactions and short-range bacterial collisions. Using direct particle simulations validated by a dedicated experiment, we show that changing the swimming speed or concentration alters the time scale of sustained collective motion, consistent with experiment. …
Ct Angiography In The Detection Of Carotid Body Enlargement In Patients With Hypertension And Heart Failure, Sreejit Nair, Ajay Gupta, Marat Fudim, Christopher Robinson, Vinay Ravi, Sandra M. Hurtado Rua, Zoar Engelman, Kyungmouk S. Lee, C. Douglas Philips, Akhilesh K. Sista
Ct Angiography In The Detection Of Carotid Body Enlargement In Patients With Hypertension And Heart Failure, Sreejit Nair, Ajay Gupta, Marat Fudim, Christopher Robinson, Vinay Ravi, Sandra M. Hurtado Rua, Zoar Engelman, Kyungmouk S. Lee, C. Douglas Philips, Akhilesh K. Sista
Mathematics and Statistics Faculty Publications
Introduction: The carotid body (CB) has previously been found to be enlarged and hyperactive in various disease states such as heart failure (HF), hypertension (HTN), and respiratory disease. Evaluation of CB size in these disease states using imaging has not been performed. The purpose of this case–control study was to compare CB sizes in patients with HF and HTN with those of controls using CT angiography. Methods: A retrospective review was performed on 323 consecutive patients who had neck computed tomography angiography (CTA) exams in 2011. Following extensive review, 17 HF and HTN patients and 14 controls were identified. Two …
Function And Distribution Of Apolipoprotein A1 In The Artery Wall Are Markedly Distinct From Those In Plasma, Joseph A. Didonato, Ying Huang, Kulwant S. Aulak, Orli Even-Or, Gary Gerstenecker, Valentin Gogonea, Yuping Wu, Paul L. Fox, W.H. Wilson Tang, Edward F. Plow, Jonathan D. Smith, Edward A. Fisher, Stanley L. Hazen
Function And Distribution Of Apolipoprotein A1 In The Artery Wall Are Markedly Distinct From Those In Plasma, Joseph A. Didonato, Ying Huang, Kulwant S. Aulak, Orli Even-Or, Gary Gerstenecker, Valentin Gogonea, Yuping Wu, Paul L. Fox, W.H. Wilson Tang, Edward F. Plow, Jonathan D. Smith, Edward A. Fisher, Stanley L. Hazen
Mathematics and Statistics Faculty Publications
Background—Prior studies show that apolipoprotein A1 (apoA1) recovered from human atherosclerotic lesions is highly oxidized. Ex vivo oxidation of apoA1 or high-density lipoprotein (HDL) cross-links apoA1 and impairs lipid binding, cholesterol efflux, and lecithin-cholesterol acyltransferase activities of the lipoprotein. Remarkably, no studies to date directly quantify either the function or HDL particle distribution of apoA1 recovered from the human artery wall. Methods and Results—A monoclonal antibody (10G1.5) was developed that equally recognizes lipid-free and HDL-associated apoA1 in both native and oxidized forms. Examination of homogenates of atherosclerotic plaque–laden aorta showed >100-fold enrichment of apoA1 compared with normal aorta (P<0.001). Surprisingly, buoyant density fractionation revealed that only a minority (<3% of total) of apoA1 recovered from either lesions or normal aorta resides within an HDL-like particle (1.063≤d≤1.21). In contrast, the majority (>90%) …
Tetrathiomolybdate-Associated Copper Depletion Decreases Circulating Endothelial Progenitor Cells In Women With Breast Cancer At High Risk Of Relapse, S. Jain, J. Cohen, M. M. Ward, N. Kornhauser, E. Chuang, T. Cigler, A. Moore, D. Donovan, C. Lam, M. V. Cobham, S. Schneider, Sandra M. Hurtado Rua, S. Benkert, C. Mathijsen Greenwood, R. Zelkowitz, J. D. Warren, M. E. Lane, V. Mittal, S. Rafii, L. T. Vahdat
Tetrathiomolybdate-Associated Copper Depletion Decreases Circulating Endothelial Progenitor Cells In Women With Breast Cancer At High Risk Of Relapse, S. Jain, J. Cohen, M. M. Ward, N. Kornhauser, E. Chuang, T. Cigler, A. Moore, D. Donovan, C. Lam, M. V. Cobham, S. Schneider, Sandra M. Hurtado Rua, S. Benkert, C. Mathijsen Greenwood, R. Zelkowitz, J. D. Warren, M. E. Lane, V. Mittal, S. Rafii, L. T. Vahdat
Mathematics and Statistics Faculty Publications
Background: Bone marrow-derived endothelial progenitor cells (EPCs) are critical for metastatic progression. This study explores the effect of tetrathiomolybdate (TM), an anti-angiogenic copper chelator, on EPCs in patients at high risk for breast cancer recurrence. Patients and methods: This phase 2 study enrolled breast cancer patients with stage 3 and stage 4 without evidence of disease (NED), and stage 2 if triple-negative. TM 100 mg orally was administered to maintain ceruloplasmin <17 mg/dl for 2 years or until relapse. The primary end point was change in EPCs. Results: Forty patients (28 stage 2/3, 12 stage 4 NED) were enrolled. Seventy-five percent patients achieved the copper depletion target by 1 month. Ninety-one percent of triple-negative patients copper-depleted compared with 41% luminal subtypes. In copper-depleted patients only, there was a significant reduction in EPCs/ml by 27 (P = 0.04). Six patients relapsed while on study, of which only one patient had EPCs maintained below baseline. The 10-month relapse-free survival was 85.0% (95% CI 74.6%–96.8%). Only grade 3/4 toxicity was hematologic: neutropenia (3.1% of cycles), febrile neutropenia (0.2%), and anemia (0.2%). Conclusions: TM is safe and appears to maintain EPCs below baseline in copper-depleted patients. TM may promote tumor dormancy and ultimately prevent relapse.
A Mathematical Model Of The Mouse Ventricular Myocyte Contraction, Paula D. Mullins, Vladimir Bondarenko
A Mathematical Model Of The Mouse Ventricular Myocyte Contraction, Paula D. Mullins, Vladimir Bondarenko
Mathematics and Statistics Faculty Publications
Mathematical models of cardiac function at the cellular level include three major components, such as electrical activity, Ca2+ dynamics, and cellular shortening. We developed a model for mouse ventricular myocyte contraction which is based on our previously published comprehensive models of action potential and Ca2+ handling mechanisms. The model was verified with extensive experimental data on mouse myocyte contraction at room temperature. In the model, we implemented variable sarcomere length and indirect modulation of the tropomyosin transition rates by Ca2+ and troponin. The resulting model described well steady-state force-calcium relationships, dependence of the contraction force on the sarcomere length, time …
Topological Complexity Of H-Spaces, Gregory Lupton, Jerome Scherer
Topological Complexity Of H-Spaces, Gregory Lupton, Jerome Scherer
Mathematics and Statistics Faculty Publications
Let X be a (not-necessarily homotopy-associative) H-space. We show that TCn+1(X) = cat (Xn), forn≥1, where TCn+1(−) denotes the so-called higher topological complexity introduced by Rudyak, and cat (−) denotes the Lusternik-Schnirelmann category. We also generalize this equality to an inequality, which gives an upper bound for TCn+1(X), in the setting of a space Y acting on X.
Detectable Subclinical Myocardial Necrosis Is Associated With Cardiovascular Risk In Stable Patients With Diabetes, W.H. Wilson Tang, Yuping Wu, Earl B. Britt Jr., Naveed Iqbal, Stanley L. Hazen
Detectable Subclinical Myocardial Necrosis Is Associated With Cardiovascular Risk In Stable Patients With Diabetes, W.H. Wilson Tang, Yuping Wu, Earl B. Britt Jr., Naveed Iqbal, Stanley L. Hazen
Mathematics and Statistics Faculty Publications
OBJECTIVE: To investigate the relationship between different degrees of subclinical myocardial necrosis, glycemic control, and long-term adverse clinical outcomes within a stable patient population with diabetes mellitus. RESEARCH DESIGN AND METHODS: We examined 1,275 stable patients with diabetes mellitus undergoing elective diagnostic coronary angiography with cardiac troponin I (cTnI) levels below the diagnostic cut-off for defining myocardial infarction (MI) (<0.03 ng/mL). The relationship of subclinical myocardial necrosis (cTnI 0.009–0.029 ng/mL) with incident major adverse cardiovascular events (MACE; defined as any death, MI, or stroke) over 3 years of follow-up was examined. RESULTS: Subclinical myocardial necrosis was observed in 22% of patients. A strong association was observed between the magnitude of subclinical myocardial necrosis and risk of 3-year incident MACE (hazard ratio, 1.98; 95% confidence interval, 1.48–2.65; P < 0.001) and remained statistically significant even after adjustment for traditional risk factors, high-sensitivity C-reactive protein, and creatinine clearance. Only a weak correlation was observed between the presence of subclinical myocardial necrosis and either glycemic control (r = 0.06; P = 0.044 for hemoglobin A1c versus cTnI) or insulin resistance (r = 0.04; P = 0.094 for glucose-to-insulin ratio versus cTnI). CONCLUSIONS: The presence of detectable subclinical myocardial necrosis in stable patients with diabetes mellitus is associated with heightened long-term risk for MACE, independent of traditional risk factors and glycemic control.
A New Optimization Algorithm For Single Hidden Layer Feedforward Neural Networks, Leong Kwan Li, Sally Shao, Ka-Fai Cedric Yiu
A New Optimization Algorithm For Single Hidden Layer Feedforward Neural Networks, Leong Kwan Li, Sally Shao, Ka-Fai Cedric Yiu
Mathematics and Statistics Faculty Publications
Feedforward neural networks are the most commonly used function approximation techniques in neural networks. By the universal approximation theorem, it is clear that a single-hidden layer feedforward neural network (FNN) is sufficient to approximate the corresponding desired outputs arbitrarily close. Some researchers use genetic algorithms (GAs) to explore the global optimal solution of the FNN structure. However, it is rather time consuming to use GA for the training of FNN. In this paper, we propose a new optimization algorithm for a single-hidden layer FNN. The method is based on the convex combination algorithm for massaging information in the hidden layer. …
Single Exhaled Breath Metabolomic Analysis Identifies Unique Breathprint In Patients With Acute Decompensated Heart Failure, Michael A. Samara, W.H. Wilson Tang, Frank Cikach Jr., Zeynep Gul, Lily Tranchito, Kelly M. Paschke, Jamie Viterna, Yuping Wu, Daniel Laskowski, Raed A. Dweik
Single Exhaled Breath Metabolomic Analysis Identifies Unique Breathprint In Patients With Acute Decompensated Heart Failure, Michael A. Samara, W.H. Wilson Tang, Frank Cikach Jr., Zeynep Gul, Lily Tranchito, Kelly M. Paschke, Jamie Viterna, Yuping Wu, Daniel Laskowski, Raed A. Dweik
Mathematics and Statistics Faculty Publications
Acute decompensated heart failure (ADHF) is the most common indication for hospital admission, particularly in the elderly, yet the identification of those with impending decompensation using conventional clinical methods is unreliable and frequently leaves insufficient lag time for therapeutic interventions (1). Exhaled breath constitutes a complex mixture of hundreds of volatile organic compounds (VOCs) that could potentially be used as a safe and noninvasive method of diagnostic and therapeutic monitoring (2). Previous research studies have identified elevated acetone, pentane, and nitric oxide levels in exhaled breath in the setting of HF correlated with disease severity (3–5). Selected ion-flow tube mass-spectrometry …
Diminished Antioxidant Activity Of High-Density Lipoprotein–Associated Proteins In Chronic Kidney Disease, David J. Kennedy, W.H. Wilson Tang, Yiying Fan, Yuping Wu, Shirley Mann, Michael Pepoy, Stanley L. Hazen
Diminished Antioxidant Activity Of High-Density Lipoprotein–Associated Proteins In Chronic Kidney Disease, David J. Kennedy, W.H. Wilson Tang, Yiying Fan, Yuping Wu, Shirley Mann, Michael Pepoy, Stanley L. Hazen
Mathematics and Statistics Faculty Publications
Background:Decreased serum arylesterase activity, catalyzed by the high-density lipoprotein–associated paraoxonase (PON)-1, is associated with increased oxidant stress and atherosclerosis risk. We sought to determine the prognostic value of serum PON-1 activity, as monitored by PON or arylesterase activities, in subjects with chronic kidney disease (CKD), particularly in relation to established cardiac biomarkers.Methods and Results: Serum arylesterase and PON activities were measured in sequential subjects with CKD (n=630; estimated glomerular filtration rate [eGFR] <60 mL/min per 1.73 m2) and an age- and sex-matched control group of non-CKD subjects (n=315) presenting for cardiac evaluations and prospectively followed for incident (3-year) major adverse cardiac events (composite of death, nonfatal myocardial infarction, and stroke). Serum arylesterase activity in CKD subjects was lower compared with that in non-CKD control subjects [median (interquartile range) 94 (77 to 112) versus 103 (85 to 121) μmol(L·min) per mL, P<0.001]; similarly, PON activity in CKD subjects was lower compared with that in non-CKD control subjects [median (interquartile range) 474 (275 to 936) versus 586 (301 to 1118) nmol(L·min) per mL, P<0.001]. Lower serum arylesterase (hazard ratio 1.8, 95% CI 1.26 to 2.57, P<0.01) was a predictor of poorer outcomes. After adjusting for traditional risk factors and medication use, lower serum arylesterase (hazard ratio 1.55, 95% CI 1.08 to 2.23, P<0.05) still conferred an increased risk of major adverse cardiac events at 3 years. Conclusions: In patients with CKD, decreased serum arylesterase activity, a measure of diminished antioxidant properties of PON-1, predicts higher risk of incident long-term adverse cardiovascular events (heart attack, stroke, or death) in multivariable models adjusting for established clinical and biochemical risk factors.
Enhanced Surveillance On Food-Borne Disease Outbreaks: Dynamics Of Cross-Contamination In Biocidal Wash Procedure, Daniel Munther, Jianhong Wu
Enhanced Surveillance On Food-Borne Disease Outbreaks: Dynamics Of Cross-Contamination In Biocidal Wash Procedure, Daniel Munther, Jianhong Wu
Mathematics and Statistics Faculty Publications
Understanding the geographic and temporal spread of food-borne diseases associated with fresh produce is crucial for informing adequate surveillance and control. As a first step towards this goal, we develop and analyze a novel three stage model at the processing/sanitization juncture in the fresh produce supply chain. The key feature of our model is its ability to describe the dynamics of cross-contamination during commercial wash procedures. In general, we quantify the degree of cross-contamination in terms of model parameters. Applying these results in the case of Escherichia coli O157:H7 contamination of fresh-cut romaine lettuce, we identify the mean wash time …
Anterior Abdominal Stab Injury: A Comparison Of Self-Inflicted And Intentional Third-Party Stabbings, Aman Banerjee, Hannah Y. Zhou, Katherine B. Kelly, Bianca D. Downs, John J. Como, Jeffrey A. Claridge
Anterior Abdominal Stab Injury: A Comparison Of Self-Inflicted And Intentional Third-Party Stabbings, Aman Banerjee, Hannah Y. Zhou, Katherine B. Kelly, Bianca D. Downs, John J. Como, Jeffrey A. Claridge
Mathematics and Statistics Faculty Publications
Background: There is minimal literature comparing self-inflicted (SI) with non–self-inflicted (NSI) anterior abdominal stab wounds (AASW). Methods: Adult patients treated at a level 1 trauma center from 2006 through 2011 with an AASW were reviewed. Results: There were 215 patients with an AASW; 20% were SI. NSI patients had more nonabdominal injuries (47% vs 16%, P < .01) and disposition directly to the operating room (45% vs 26%, P = .02). Intra-abdominal injury rates were similar. One hundred twenty-eight patients had isolated AASWs; 28% were SI. SI patients had higher admission rates (86% vs 63%, P = .01). One hundred three patients had isolated stable/asymptomatic AASWs; 31% were SI. SI patients had more admissions (84% vs 52%, P < .01), had higher intensive care unit admission rates (23% vs 5%, P = .01), longer LOS (3.2 vs 1.4, P < .01), and higher hospital charges ($18,000 vs $11,000, P < .01). The rates of intra-abdominal injury were again similar. Conclusions: Controlling for extra-abdominal injuries, SI AASW patients have similar rates of intra-abdominal injury but use more resources.
Toric Complete Intersection Codes, Ivan Soprunov
Toric Complete Intersection Codes, Ivan Soprunov
Mathematics and Statistics Faculty Publications
In this paper we construct evaluation codes on zero-dimensional complete intersections in toric varieties and give lower bounds for their minimum distance. This generalizes the results of Gold–Little–Schenck and Ballico–Fontanari who considered evaluation codes on complete intersections in the projective space.
The Ideal Free Strategy With Weak Allee Effect, Daniel Munther
The Ideal Free Strategy With Weak Allee Effect, Daniel Munther
Mathematics and Statistics Faculty Publications
This paper examines the interplay between optimal movement strategies and the weak Allee effect within the context of two competing species in a spatially heterogenous environment. When both species have the same populations dynamics, previous studies identified an ‘ideal free’ strategy which is able to exclude any other competitor playing a ‘non-ideal free’ strategy. We find that if the ideal free disperser is subject to a weak Allee effect, a competing species utilizing very weak or very strong advection will still be excluded despite having superior population dynamics. However, for intermediate advection rates, such a competitor can invade the ideal …
Usefulness Of Cardiac Biomarker Score For Risk Stratification In Stable Patients Undergoing Elective Cardiac Evaluation Across Glycemic Status, W.H. Wilson Tang, Naveed Iqbal, Yuping Wu, Stanley L. Hazen
Usefulness Of Cardiac Biomarker Score For Risk Stratification In Stable Patients Undergoing Elective Cardiac Evaluation Across Glycemic Status, W.H. Wilson Tang, Naveed Iqbal, Yuping Wu, Stanley L. Hazen
Mathematics and Statistics Faculty Publications
Several clinically available cardiac biomarkers have established their prognostic value in patients with acute coronary syndromes. However, their relative prognostic significance in stable subjects has not been prospectively validated, either individually or in combination. The aim of this study was to evaluate the extent to which B-type natriuretic peptide, myeloperoxidase, and high-sensitivity C-reactive protein alone or together could be prognostic biomarkers in 3,635 consecutive stable patients without acute coronary syndrome who underwent elective diagnostic coronary angiography. After adjusting for traditional risk factors and renal function, each of the markers monitored was a significant predictor of incident major adverse cardiovascular events …
Some Minor-Closed Classes Of Signed Graphs, Dan Slilaty, Xiangqian Zhou
Some Minor-Closed Classes Of Signed Graphs, Dan Slilaty, Xiangqian Zhou
Mathematics and Statistics Faculty Publications
We define four minor-closed classes of signed graphs in terms of embeddability in the annulus, projective plane, torus, and Klein bottle. We give the full list of 20 excluded minors for the smallest class and make a conjecture about the largest class.
Adaptive And Sequential Methods For Clinical Trials, Yichuan Zhao, Zhengjia Chen, Xuelin Huang, Mourad Tighiouart
Adaptive And Sequential Methods For Clinical Trials, Yichuan Zhao, Zhengjia Chen, Xuelin Huang, Mourad Tighiouart
Mathematics and Statistics Faculty Publications
This special issue describes state-of-the-art statistical research in adaptive and sequential methods and the application of such methods in clinical trials. It provides 1 review article and 5 research articles contributed by some of the leading experts in this field. The review article gives a comprehensive overview of the outstanding methodology in the current literature that is related to adaptive and sequential clinical trials, while each of the 5 research articles addresses specific critical issues in contemporary clinical trials, as summarized below.