1,649 research outputs found

    Conservation laws for self-adjoint first order evolution equations

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    In this work we consider the problem on group classification and conservation laws of the general first order evolution equations. We obtain the subclasses of these general equations which are quasi-self-adjoint and self-adjoint. By using the recent Ibragimov's Theorem on conservation laws, we establish the conservation laws of the equations admiting self-adjoint equations. We illustrate our results applying them to the inviscid Burgers' equation. In particular an infinite number of new symmetries of these equations are found and their corresponding conservation laws are established.Comment: This manuscript has been accepted for publication in Journal of Nonlinear Mathematical Physic

    Risk factors associated with Helicobacter pylori infection treatment failure in a high prevalence area

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    Triple therapy is commonly used for the treatment of Helicobacter pylori infection. We determined risk factors associated with its failure in compliant Patients focusing on H. pylori density, virulence marker and 23S ribosomal RNA (rRNA) point mutations associated with clarithromycin resistance. H. pylori infection was diagnosed by (14)C urea breath test ((14)C UBT) and rapid urease test or histology. Triple therapy with esomeprazole 20 mg b.i.d., amoxicillin 1 g b.i.d. and clarithromycin 500 mg b.i.d. was prescribed for 10 days. 14C UBT was repeated 4 weeks after treatment. In total, 111 Patients [69 (62%) males] with a mean age of 46 +/- 16 years were enrolled. The mean age of treatment failure was 39 +/- 14 years compared to 48 +/- 16 years with eradication (P=0.002). Treatment failure was associated with younger mean age, point mutations in the 23S rRNA gene of H. pylori and vacA s1a and m1 when associated with cagA negativity

    Using Indium-111 labeled radiopharmaceuticals to target the BB2 receptor on human prostate cancer cells [abstract]

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    Abstract only availableThe BB2 receptor, belonging to the Bombesin receptor family, has been shown to be highly over expressed in a variety of cancer cell lines, including human prostate cancer. Our laboratory have been involved, for over a decade, in synthesizing Bombesin analogues that target the BB2 receptor for the purpose of developing radiopharmaceuticals for diagnostic and/or therapeutic treatment of cancer. Radiopharmaceuticals based on Bombesin are typically composed of a chelator, isotope, linking group and targeting vector [See Bifunctional Conjugate Design [figure below]. Previous studies by our group and others have shown that variations in linking groups affect the retention time of the bifunctional conjugate in prostate cancer (PC-3) cells. Higher retention time allows for more efficacious therapeutic benefits and enhanced diagnostic imaging capabilities. In this study, we seek to determine the pharmacokinetic benefits achieved in altering the linking group using aliphatic and aromatic linking groups. In-vitro analysis of the radiopharmaceuticals studied found that the Bombesin derivative with the aliphatic linking group demonstrated a slightly higher affinity for the BB2 receptor compared to the Bombesin analogs containing aromatic linking groups. In vivo pharmacokinetic and imaging studies were performed using pre-clinical models of prostate cancer. The tumor uptake of the Bombesin derivatives with the aromatic linking groups were found to be significantly higher compared to that of the Bombesin derivative with the aliphatic linking group. In contrast, the aromatic Bombesin analogs also exhibited higher amounts of undesirable accumulation in the kidneys and other non-target tissues. In conclusion, we found that the aliphatic compounds were more appropriate for diagnostic imaging of prostate cancer due to the reduced non-target retention. The Bombesin analogs with aromatic linking groups showed potential for use as therapeutic agents for prostate cancer treatment.National Institutes of Health Molecular Imaging Progra

    Self-terminating re-entrant cardiac arrhythmias: quantitative characterization

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    Atrial and ventricular tachyarrhythmia are often sustained by re-entrant propagation, and explained by deterministic models. A quantitative, stochastic description of self-termination provides an alternative to the current paradigm for re-entrant tachyarrhythmia - that of triggers and a substrate, modelled by parametrically heterogeneous deterministic partial differential equations. Atrial and ventricular data was from recordings obtained during routine clinical monitoring and treatment, either noninvasively or invasively. Atrial and ventricular tachycardia are characterised by their initiation times and durations, re-presented as instantaneous rates, whose means estimate transition probabilities/s for onset and termination. These estimated probabilities range from 10(-9) to 10(-1)/s
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