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Search Results: 1 - 10 of 205015 matches for " P. Ryan Clarke "
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Cyclic Subsets and Barnette's Conjecture
P. Clarke
Mathematics , 2013,
Abstract: In this paper, the concept of cyclic subsets in graph theory is introduced. An interesting theorem which relates to the collective Hamiltonicity of these cyclic subsets in graphs is also presented. This paper uses this theorem to construct an inductive proof of Barnette's long-standing conjecture, which asks whether every cubic, polyhedral, bipartite graph is Hamiltonian. Finding a class of graphs that are certain to be Hamiltonian is one of the biggest unsolved problems in Hamiltonian graph theory today.
Cycle Double Cover Conjecture
P. Clarke
Mathematics , 2014,
Abstract: In this paper, a proof of the cycle double cover conjecture is presented. The cycle double cover conjecture purports that if a graph is bridgeless, then there exists a list of cycles in the graph such that every edge in the graph appears in the list exactly twice. By applying induction on the number of edges in a bridgeless graph, I show that when an edge is added to a bridgeless graph, we can reform the cycle double cover to include that edge. By mathematical induction, this concludes the general CDC.
A Search Procedure for Cyclic Subsets
P. Clarke
Computer Science , 2014,
Abstract: In this paper, a polynomial time algorithm for finding the set of all cyclic subsets in a graph is presented. The concept of cyclic subsets has already been introduced in an earlier paper. The algorithm finds cyclic subsets in a graph G by conjoining building block subsets of length three in V(G). We prove the correctness of this algorithm and present an asymptotic time complexity analysis of the algorithm's performance.
Shared Bacterial and Viral Respiratory Agents in Bighorn Sheep (Ovis canadensis), Domestic Sheep (Ovis aries), and Goats (Capra hircus) in Montana
David S. Miller,Glen C. Weiser,Keith Aune,Brent Roeder,Mark Atkinson,Neil Anderson,Thomas J. Roffe,Kim A. Keating,Phillip L. Chapman,Cleon Kimberling,Jack Rhyan,P. Ryan Clarke
Veterinary Medicine International , 2011, DOI: 10.4061/2011/162520
Abstract: Transmission of infectious agents from livestock reservoirs has been hypothesized to cause respiratory disease outbreaks in bighorn sheep (Ovis canadensis), and land management policies intended to limit this transmission have proven controversial. This cross-sectional study compares the infectious agents present in multiple populations of bighorn sheep near to and distant from their interface with domestic sheep (O. aries) and domestic goat (Capra hircus) and provides critical baseline information needed for interpretations of cross-species transmission risks. Bighorn sheep and livestock shared exposure to Pasteurellaceae, viral, and endoparasite agents. In contrast, although the impact is uncertain, Mycoplasma sp. was isolated from livestock but not bighorn sheep. These results may be the result of historic cross-species transmission of agents that has resulted in a mosaic of endemic and exotic agents. Future work using longitudinal and multiple population comparisons is needed to rigorously establish the risk of outbreaks from cross-species transmission of infectious agents. 1. Introduction Bighorn sheep (Ovis canadensis) experienced substantial decreases in population numbers and range in the 19th and the early 20th centuries, and subsequent recovery efforts have often been limited by large-scale die-offs [1–3]. These initial population declines were associated with settlement of western North America and were attributed to unregulated hunting, competition for forage with domestic sheep (O. aries) and other livestock, and disruption of historic bighorn sheep migration patterns due to development. Clinical disease was apparently unimportant or was underreported in these early declines, though die-offs of bighorn sheep associated with sheep scab (Psoroptes sp.) were reported following settlement [4, 5]. Bighorn sheep die-offs associated with pneumonia were reported in the 1920s and 1930s [6–10]. These early reports and subsequent work largely focused on lungworm (Protostrongylus sp.) as the primary infectious agent, although the involvement of Pasteurella sp., Corynebacterium pyogenes (currently Arcanobacterium pyogenes), and other host and environmental determinants were also noted as potential causes of respiratory disease. Subsequently, inconsistent association of lungworm with respiratory disease in bighorn sheep, as well as further evidence for Pasteurella sp. as the cause of pneumonia, led to a focus on pasteurellosis as a cause of respiratory disease outbreaks [11–14]. This research included evidence that Pasteurella sp. strains from clinically
Single-top Cross Section Measurements at ATLAS
P. Ryan
Physics , 2008,
Abstract: The single-top production cross section is one third that of the top-pair production cross section at the LHC. During a year of data-taking, assuming an average luminosity of 10^33 cm-2 s-1 and a CMS energy of 14 TeV, the determination of the major contributions to the total single-top cross section should be achievable. Comparisons between the measured cross sections and the theoretical predictions will provide a crucial test of the standard model. These measurements should also lead to the first direct measurement of |V_tb|, with a precision at the level of a few percent. In addition, they will probe for new physics via the search for evidence of anomalous couplings to the top quark and the measurements of additional bosonic contributions to single-top production. Methods developed to optimize the selection of single-top events in the three production channels are presented and the potential for the cross section measurements with 1 fb-1 and 30 fb-1 of integrated luminosity is established.
Relative expression of progesterone receptors A and B in premalignant and invasive breast lesions
P Mote, C Clarke
Breast Cancer Research , 2000, DOI: 10.1186/bcr103
Abstract: This study examined the expression of PRA and PRB proteins in normal breast tissue (n =13) during the menstrual cycle, and in premalignant (n =45) and malignant (n =39) breast tissues, to determine differences in relative isoform expression.We used dual immunofluorescent histochemistry on formalin-fixed, paraffin-embedded tissue sections using mouse monoclonal antibodies that bind to either PRB or PRA.In most normal breast cases PR staining was confined to scattered epithelial cells expressing equivalent levels of PRA and PRB. However, 50% of cases in the luteal phase (n =6) showed reduced PRA expression. In proliferative premalignant lesions without atypia (PDWA, n =15), there was a marked increase in intensity and number of cells expressing PR, but inter-cell homogeneity was maintained. Atypical proliferative benign lesions (ADH, n =15; DCIS, n =15), showed high levels of both PRA and PRB expression with notable inter-cell heterogeneity in relative isoform content. This was also observed in malignant breast tumours (n =39). Furthermore, breast tumours expressing an overall predominance of one isoform were associated with features of higher histological grade.In conclusion, our results show a change from inter-cell homogeneity of PRA:PRB in normal tissue to extensive heterogeneity in the malignant state, suggesting a progressive loss of control of relative PRA and B expression that may occur early in cancer development and may eventually be associated with features of poorer prognosis.
Synthesis of Gemcitabine-(C4-amide)-[anti-HER2/neu] Utilizing a UV-Photoactivated Gemcitabine Intermediate: Cytotoxic Anti-Neoplastic Activity against Chemotherapeutic-Resistant Mammary Adenocarcinoma SKBr-3  [PDF]
Cody P. Coyne, Toni Jones, Ryan Bear
Journal of Cancer Therapy (JCT) , 2012, DOI: 10.4236/jct.2012.325089
Abstract: Gemcitabine is a pyrimidine nucleoside analog that becomes triphosphorylated intracellularly where it competitively inhibits cytidine incorporation into DNA strands. Another mechanism-of-action of gemcitabine (diphosphorylated form) involves irreversible inhibition of the enzyme ribonucleotide reductase thereby preventing deoxyribonucleotide synthesis. Functioning as a potent chemotherapeutic gemcitabine promote decreases in neoplastic cell proliferation and apoptosis which is frequently found to be effective for the treatment of several leukemias and a wide spectrum of carcinomas. A brief plasma half-life in part due to rapid deamination and chemotherapeutic-resistance restricts the utility of gemcitabine in clinical oncology. Selective “targeted” delivery of gemcitabine represents a potential molecular strategy for simultaneously prolonging its plasma half-life and minimizing innocient tissues and organ systems exposure to chemotherapy. The molecular design and an organic chemistry based synthesis reaction is described that initially generates a UV-photoactivated gemcitabine intermediate. In a subsequent phase of the synthesis method the UV-photoactivated gemcitabine intermediate is covalently bonded to a monoclonal immunoglobulin yielding an end-product in the form of gemcitabine-(C4-amide)-[anti-HER2/neu]. Analysis by SDS-PAGE/chemiluminescent auto-radiography did not detect evidence of gemcitabine-(C4-amide)-[anti-HER2/neu] polymerization or degradative fragmentation while cell-ELISA demonstrated retained binding-avidity for HER2/neu trophic membrane receptor complexes highly over-expressed by chemotherapeutic-resistant mammary adenocarcinoma (SKBr-3). Compared to chemotherapeutic-resistant mammary adenocarcinoma (SKBr-3), the covalent immunochemotherapeutic, gemcitabine-(C4-amide)-[anti-HER2/neu] is anticipated to exert greater levels of cytotoxic anti-neoplastic potency against other neoplastic cell types like pancreatic carcinoma, small-cell lung carcinoma, neuroblastoma, glioblastoma, oral squamous cell carcinoma, cervical epitheliod carcinoma, or leukemia/lymphoid neoplastic cell types based on their reported sensitivity to gemcitabine and gemcitabine covalent conjugates.
Simultaneous Dual Selective Targeted Delivery of Two Covalent Gemcitabine Immunochemotherapeutics and Complementary Anti-Neoplastic Potency of [Se]-Methylselenocysteine  [PDF]
C. P. Coyne, Toni Jones, Ryan Bear
Journal of Cancer Therapy (JCT) , 2015, DOI: 10.4236/jct.2015.61009

The anti-metabolite chemotherapeutic, gemcitabine is relatively effective for a spectrum of neoplastic conditions that include various forms of leukemia and adenocarcinoma/carcinoma. Rapid systemic deamination of gemcitabine accounts for a brief plasma half-life but its sustained administration is often curtailed by sequelae and chemotherapeutic-resistance. A molecular strategy that diminishes these limitations is the molecular design and synthetic production of covalent gemcitabine immunoche-motherapeutics that possess properties of selective “targeted” delivery. The simultaneous dual selective “targeted” delivery of gemcitabine at two separate sites on the external surface membrane of a single cancer cell types represents a therapeutic approach that can increase cytosol chemotherapeutic deposition; prolong chemotherapeutic plasma half-life (reduces administration frequency); minimize innocent exposure of normal tissues and healthy organ systems; and ultimately enhance more rapid and thorough resolution of neoplastic cell populations. Materials and Methods: A light-reactive gemcitabine intermediate synthesized utilizing succinimidyl 4,4-azipentanoate was covalently bound to anti-EGFR or anti-HER2/neu IgG by exposure to UV light (354-nm) resulting in the synthesis of covalent immunoche-motherapeutics, gemcitabine-(C4-amide)-[anti-EGFR] and gemcitabine-(C4-amide)-[anti-HER2/neu]. Cytotoxic anti-neoplastic potency of gemcitabine-(C4-amide)-[anti-EGFR] and gemcitabine-(C4-amide)-[anti-HER2/neu] between gemcitabine-equivalent concentrations of 10-12 M and 10-6 M was determined utilizing chemotherapeutic-resistant mammary adenocarcinoma (SKRr-3). The organoselenium compound, [Se]-methylselenocysteine was evaluated to determine if it complemented the anti-neoplastic potency of the covalent gemcitabine immunoche-motherapeutics. Results: Gemcitabine-(C4-

Pharmaceutical Sponsorship Bias Influences Thrombolytic Literature in Acute Ischemic Stroke
Ryan P Radecki
Western Journal of Emergency Medicine : Integrating Emergency Care with Population Health , 2011,
Abstract: Background: The efficacy of thrombolytic therapy for acute ischemic stroke remains controversial in Emergency Medicine and has not been fully endorsed by either the American College of Emergency Physicians or the American Academy of emergency medicine. A growing recognition exists of the influence of pharmaceutical sponsorship on the reported findings of published clinical trials. Sponsorship bias has been suggested as a potential criticism of the literature and guidelines favoring thrombolytic therapy. Objective: The objective of this study is to review the most influential literature regarding thrombolytic therapy for acute ischemic stroke and document the presence or absence of pharmaceutical sponsorship. Methods: A publication-citation analysis was performed to identify the most frequently cited articles pertaining to thrombolytic therapy for acute ischemic stroke. Identified articles were reviewed for disclosures of pharmaceutical funding. Results: Of the 20 most-cited articles pertaining to thrombolytic therapy for acute stroke, 17 (85%) disclosed pharmaceutical sponsorship. These disclosures range from general sponsorship to direct employment of authors by pharmaceutical companies. Conclusion: An overwhelming predominance of the most influential literature regarding thrombolytic therapy for acute ischemic stroke is susceptible to sponsorship bias. This potential bias may provide a basis for physician concern regarding the efficacy and safety of thrombolytic therapy. Further, large, independent, placebo-controlled studies may be required to guide therapy and professional guidelines definitively for acute ischemic stroke. [West J Emerg Med. 2011;12(4):435–441.]
David George Hogarth at Asyut, Egypt, 1906-1907. The History of a "lost" Excavation
Donald P. Ryan
Bulletin of the History of Archaeology , 1995, DOI: 10.5334/bha.05202
Abstract: While engaged in a study of ancient Egyptian cordage in the British Museum during 1984, I came across a fragment of rope recovered from Asyut, Egypt, by the British archaeologist, D.G. Hogarth. In investigating this artifact, I learned that this excava-tion by Hogarth was known to very few scholars and had never been published. Intrigued by the data I encountered in Hogarth's notes, I initiated a project to organize, clarify, and make available the information found therein. A reconstructed excavation report based on Hogarth's field notes, correspondence and British Museum records is currently in press (Ryan, in press). Apart from the archaeological data itself which is of significant Egyptological interest, Hogarth's material provides an intriguing personal glimpse at the goings-on of an Egyptian excavation in the early part of the 20th century. Various documents provide much of the story from the conception of the idea for an expedition to the ultimate disposition of many of the artifacts derived therefrom.
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