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Search Results: 1 - 10 of 241442 matches for " James R. Burke "
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Active Management of Plant Canopy Temperature as a Tool for Modifying Plant Metabolic Activity  [PDF]
James R. Mahan, John J. Burke
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.61028
Abstract: The relationship between a plant and its thermal environment is a major determiner of its growth and development. Since plants grow and develop within continuously variable thermal environments, they are subjected to continuous thermal variation over their life cycle. Transpiration serves to uncouple the temperature of the plant from that of its environment in a manner that reduces the occurrence of high temperature stresses that can limit plant performance. In some agriculturally important plants, there are desirable metabolic outcomes that are associated with specific stress events (e.g. wine grapes). In these plants it is often desirable to induce temperature and water stresses of known magnitude and duration at specific points in the growing season. In this study we used a computer-controlled irrigation system that used cotton canopy temperature to control irrigation in greenhouse-grown plants over a 10-day period. The system was designed to irrigate in a manner that altered the canopy temperature relative to specific temperature thresholds (28°C, 30°C, 32°C and 34°C). The results demonstrate that automated irrigation management based on canopy temperature is capable of altering the temporal pattern of canopy temperature in a desired manner using a feed-back loop. Potential limitations on this action are related to the range of air temperatures, radiation and humidity within the environment.
Spontaneous coronary dissection presenting with reperfusion arrhythmia: A case report  [PDF]
Khawar Maqsood, Muhammad R. Sardar, Marwan Badri, James F. Burke, Wajeeha Saeed, Ghazi Mirrani, Nosheen Sarwar, Joseph Kusick, Frank C. McGeehin, Paul M. Coady
Case Reports in Clinical Medicine (CRCM) , 2013, DOI: 10.4236/crcm.2013.23058

Spontaneous coronary dissection is more commonly reported in females and is an important differential diagnosis for acute coronary syndrome. Accelerated idioventricular rhythm has been reported before with reperfusion post myocardial ischemia. We report a case of accelerated idioventricular rhythm in a patient with spontaneous coronary artery dissection. A 45-year-old Caucasian female presented with left sided chest pain radiating to the neck and palpitations. Admission ECG showed accelerated idioventricular rhythm. Troponin I peaked at 0.5 ng/ml. Coronary angiography showed mid to distal left anterior descending artery dissection with adequate distal flow. Patient was initially medically managed with aspirin, metoprolol, intravenous heparin and eptifibatide infusions but continued to have symptoms of unstable angina. She underwent successful percutaneous coronary intervention with 2 drug eluting stents and was discharged back home symptom free on dual platelet therapy. Spontaneous coronary artery dissection is an important differential diagnosis for acute coronary syndrome especially in younger females. Accelerated idioventricular rhythm can be a presentation of coronary dissection and may indicate instability. Early percutaneous coronary intervention should be considered in such patients.

Widespread Genome Reorganization of an Obligate Virus Mutualist
Gaelen R. Burke ,Kimberly K. O. Walden,James B. Whitfield,Hugh M. Robertson,Michael R. Strand
PLOS Genetics , 2014, DOI: doi/10.1371/journal.pgen.1004660
Abstract: The family Polydnaviridae is of interest because it provides the best example of viruses that have evolved a mutualistic association with their animal hosts. Polydnaviruses in the genus Bracovirus are strictly associated with parasitoid wasps in the family Braconidae, and evolved ~100 million years ago from a nudivirus. Each wasp species relies on its associated bracovirus to parasitize hosts, while each bracovirus relies on its wasp for vertical transmission. Prior studies establish that bracovirus genomes consist of proviral segments and nudivirus-like replication genes, but how these components are organized in the genomes of wasps is unknown. Here, we sequenced the genome of the wasp Microplitis demolitor to characterize the proviral genome of M. demolitor bracovirus (MdBV). Unlike nudiviruses, bracoviruses produce virions that package multiple circular, double-stranded DNAs. DNA segments packaged into MdBV virions resided in eight dispersed loci in the M. demolitor genome. Each proviral segment was bounded by homologous motifs that guide processing to form mature viral DNAs. Rapid evolution of proviral segments obscured homology between other bracovirus-carrying wasps and MdBV. However, some domains flanking MdBV proviral loci were shared with other species. All MdBV genes previously identified to encode proteins required for replication were identified. Some of these genes resided in a multigene cluster but others, including subunits of the RNA polymerase that transcribes structural genes and integrases that process proviral segments, were widely dispersed in the M. demolitor genome. Overall, our results indicate that genome dispersal is a key feature in the evolution of bracoviruses into mutualists.
Radiometals in Diagnosis and Therapy
James F. Burke
Metal-Based Drugs , 1997, DOI: 10.1155/mbd.1997.153
Resonant magnetic field control of elastic scattering of cold 85Rb
J. L. Roberts,N. R. Claussen,James P. Burke, Jr.,Chris H. Greene,E. A. Cornell,C. E. Wieman
Physics , 1998,
Abstract: A magnetic field dependent Feshbach resonance has been observed in the elastic scattering collision rate between atoms in the F = 2, M = -2 state of 85 Rb. Changing the magnetic field by several Gauss caused the collision rate to vary by a factor of 10,000, and the sign of the scattering length could be reserved. The resonance peak is at 155.2(4) G and its width is 11.6(5) G. From these results we extract much improved values for the three quantities that characterize the interaction porential: the van der Waals coefficient C6, the singlet scattering length, and the triplet scattering length.
Epi-convergent Smoothing with Applications to Convex Composite Functions
James V. Burke,Tim Hoheisel
Mathematics , 2012,
Abstract: Smoothing methods have become part of the standard tool set for the study and solution of nondifferentiable and constrained optimization problems as well as a range of other variational and equilibrium problems. In this note we synthesize and extend recent results due to Beck and Teboulle on infimal convolution smoothing for convex functions with those of X. Chen on gradient consistency for nonconvex functions. We use epi-convergence techniques to define a notion of epi-smoothing that allows us to tap into the rich variational structure of the subdifferential calculus for nonsmooth, nonconvex, and nonfinite-valued functions. As an illustration of the versatility and range of epi-smoothing techniques, the results are applied to the general constrained optimization for which nonlinear programming is a special case.
Variational Analysis of Convexly Generated Spectral Max Functions
James V. Burke,Julia Eaton
Mathematics , 2015,
Abstract: The spectral abscissa is the largest real part of an eigenvalue of a matrix and the spectral radius is the largest modulus of an eigenvalue of a matrix. Both are examples of spectral max-functions, which are the maximum of real-valued functions over the eigenvalues, or spectrum, of a matrix. The spectral abscissa and radius arise in problems in control and stabilization for dynamical systems. In 2001, Burke and Overton characterized the regular subdifferential of the spectral abscissa and show that the spectral abscissa is subdifferentially regular in the sense of Clarke on the set of matrices with nonderogatory eigenvalues. Using a new technique of proof, we extend the subdifferential regularity result to the broader class of convexly generated spectral max-functions where the maximum is taken over a real-valued convex function on the spectrum.
The Aggregation Inhibitor Peptide QBP1 as a Therapeutic Molecule for the Polyglutamine Neurodegenerative Diseases
H. Akiko Popiel,James R. Burke,Warren J. Strittmatter,Shinya Oishi,Nobutaka Fujii,Toshihide Takeuchi,Tatsushi Toda,Keiji Wada,Yoshitaka Nagai
Journal of Amino Acids , 2011, DOI: 10.4061/2011/265084
Abstract: Misfolding and abnormal aggregation of proteins in the brain are implicated in the pathogenesis of various neurodegenerative diseases including Alzheimer's, Parkinson's, and the polyglutamine (polyQ) diseases. In the polyQ diseases, an abnormally expanded polyQ stretch triggers misfolding and aggregation of the disease-causing proteins, eventually resulting in neurodegeneration. In this paper, we introduce our therapeutic strategy against the polyQ diseases using polyQ binding peptide 1 (QBP1), a peptide that we identified by phage display screening. We showed that QBP1 specifically binds to the expanded polyQ stretch and inhibits its misfolding and aggregation, resulting in suppression of neurodegeneration in cell culture and animal models of the polyQ diseases. We further demonstrated the potential of protein transduction domains (PTDs) for in vivo delivery of QBP1. We hope that in the near future, chemical analogues of aggregation inhibitor peptides including QBP1 will be developed against protein misfolding-associated neurodegenerative diseases. 1. Introduction Neurodegenerative diseases are a group of disorders, which are caused by progressive degeneration of neurons in various areas of the brain specific for each disorder, resulting in various neurological and psychiatric symptoms corresponding to each affected brain area. Few effective therapies have been established to date for these diseases, largely due to the fact that the underlying cause of the neurodegeneration long remained unknown. However, accumulating evidence now indicates that many of these neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD), the polyglutamine (polyQ) diseases, amyotrophic lateral sclerosis, and the prion diseases, share a common pathomechanism (Figure 1). Pathological and biochemical studies have revealed that various protein inclusions accumulate inside and outside of neurons in the diseased brains, such as senile plaques composed of amyloid-β and neurofibrillary tangles composed of tau in AD, and Lewy bodies composed of α-synuclein in PD. Although the significance of these protein inclusions on disease pathology long remained controversial, recent molecular genetics studies revealed that the mutations responsible for the inherited forms of these diseases render the proteins to be prone to misfold and aggregate, or lead to the overproduction of aggregation-prone proteins. Furthermore, not only such genetic mutations, but also multiple environmental factors are thought to trigger the misfolding of otherwise normal proteins, and
Local Variations in Spatial Synchrony of Influenza Epidemics
James H. Stark,Derek A. T. Cummings,Bard Ermentrout,Stephen Ostroff,Ravi Sharma,Samuel Stebbins,Donald S. Burke,Stephen R. Wisniewski
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0043528
Abstract: Understanding the mechanism of influenza spread across multiple geographic scales is not complete. While the mechanism of dissemination across regions and states of the United States has been described, understanding the determinants of dissemination between counties has not been elucidated. The paucity of high resolution spatial-temporal influenza incidence data to evaluate disease structure is often not available.
Metabolomics in Early Alzheimer's Disease: Identification of Altered Plasma Sphingolipidome Using Shotgun Lipidomics
Xianlin Han, Steve Rozen, Stephen H. Boyle, Caroline Hellegers, Hua Cheng, James R. Burke, Kathleen A. Welsh-Bohmer, P. Murali Doraiswamy, Rima Kaddurah-Daouk
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0021643
Abstract: Background The development of plasma biomarkers could facilitate early detection, risk assessment and therapeutic monitoring in Alzheimer's disease (AD). Alterations in ceramides and sphingomyelins have been postulated to play a role in amyloidogensis and inflammatory stress related neuronal apoptosis; however few studies have conducted a comprehensive analysis of the sphingolipidome in AD plasma using analytical platforms with accuracy, sensitivity and reproducibility. Methods and Findings We prospectively analyzed plasma from 26 AD patients (mean MMSE 21) and 26 cognitively normal controls in a non-targeted approach using multi-dimensional mass spectrometry-based shotgun lipidomics [1], [2] to determine the levels of over 800 molecular species of lipids. These data were then correlated with diagnosis, apolipoprotein E4 genotype and cognitive performance. Plasma levels of species of sphingolipids were significantly altered in AD. Of the 33 sphingomyelin species tested, 8 molecular species, particularly those containing long aliphatic chains such as 22 and 24 carbon atoms, were significantly lower (p<0.05) in AD compared to controls. Levels of 2 ceramide species (N16:0 and N21:0) were significantly higher in AD (p<0.05) with a similar, but weaker, trend for 5 other species. Ratios of ceramide to sphingomyelin species containing identical fatty acyl chains differed significantly between AD patients and controls. MMSE scores were correlated with altered mass levels of both N20:2 SM and OH-N25:0 ceramides (p<0.004) though lipid abnormalities were observed in mild and moderate AD. Within AD subjects, there were also genotype specific differences. Conclusions In this prospective study, we used a sensitive multimodality platform to identify and characterize an essentially uniform but opposite pattern of disruption in sphingomyelin and ceramide mass levels in AD plasma. Given the role of brain sphingolipids in neuronal function, our findings provide new insights into the AD sphingolipidome and the potential use of metabolomic signatures as peripheral biomarkers.
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