On the generalized Hamiltonian structure of 3D dynamical systems

The Poisson structures for 3D systems possessing one constant of motion can always be constructed from the solution of a linear PDE. When two constants of the motion are available the problem reduces to a quadrature and the structure functions include an arbitrary function of them

Symplectic quantization, inequivalent quantum theories, and Heisenberg's principle of uncertainty

We analyze the quantum dynamics of the non-relativistic two-dimensional isotropic harmonic oscillator in Heisenberg's picture. Such a system is taken as toy model to analyze some of the various quantum theories that can be built from the application of Dirac's quantization rule to the various symplectic structures recently reported for this classical system. It is pointed out that that these quantum theories are inequivalent in the sense that the mean values for the operators (observables) associated with the same physical classical observable do not agree with each other. The inequivalence does not arise from ambiguities in the ordering of operators but from the fact of having several symplectic structures defined with respect to the same set of coordinates. It is also shown that the uncertainty relations between the fundamental observables depend on the particular quantum theory chosen. It is important to emphasize that these (somehow paradoxical) results emerge from the combination of two paradigms: Dirac's quantization rule and the usual Copenhagen interpretation of quantum mechanics.Comment: 8 pages, LaTex file, no figures. Accepted for publication in Phys. Rev.

Multivector Field Formulation of Hamiltonian Field Theories: Equations and Symmetries

We state the intrinsic form of the Hamiltonian equations of first-order Classical Field theories in three equivalent geometrical ways: using multivector fields, jet fields and connections. Thus, these equations are given in a form similar to that in which the Hamiltonian equations of mechanics are usually given. Then, using multivector fields, we study several aspects of these equations, such as the existence and non-uniqueness of solutions, and the integrability problem. In particular, these problems are analyzed for the case of Hamiltonian systems defined in a submanifold of the multimomentum bundle. Furthermore, the existence of first integrals of these Hamiltonian equations is considered, and the relation between {\sl Cartan-Noether symmetries} and {\sl general symmetries} of the system is discussed. Noether's theorem is also stated in this context, both the ``classical'' version and its generalization to include higher-order Cartan-Noether symmetries. Finally, the equivalence between the Lagrangian and Hamiltonian formalisms is also discussed.Comment: Some minor mistakes are corrected. Bibliography is updated. To be published in J. Phys. A: Mathematical and Genera

N-Termini of Fungal CSL Transcription Factors Are Disordered, Enriched in Regulatory Motifs and Inhibit DNA Binding in Fission Yeast

Background: CSL (CBF1/RBP-J kappa/Suppressor of Hairless/LAG-1) transcription factors are the effector components of the Notch receptor signalling pathway, which is critical for metazoan development. The metazoan CSL proteins (class M) can also function in a Notch-independent manner. Recently, two novel classes of CSL proteins, designated F1 and F2, have been identified in fungi. The role of the fungal CSL proteins is unclear, because the Notch pathway is not present in fungi. In fission yeast, the Cbf11 and Cbf12 CSL paralogs play antagonistic roles in cell adhesion and the coordination of cell and nuclear division. Unusually long N-terminal extensions are typical for fungal and invertebrate CSL family members. In this study, we investigate the functional significance of these extended N-termini of CSL proteins.Methodology/Principal Findings: We identify 15 novel CSL family members from 7 fungal species and conduct bioinformatic analyses of a combined dataset containing 34 fungal and 11 metazoan CSL protein sequences. We show that the long, non-conserved N-terminal tails of fungal CSL proteins are likely disordered and enriched in phosphorylation sites and PEST motifs. In a case study of Cbf12 (class F2), we provide experimental evidence that the protein is proteolytically processed and that the N-terminus inhibits the Cbf12-dependent DNA binding activity in an electrophoretic mobility shift assay.Conclusions/Significance: This study provides insight into the characteristics of the long N-terminal tails of fungal CSL proteins that may be crucial for controlling DNA-binding and CSL function. We propose that the regulation of DNA binding by Cbf12 via its N-terminal region represents an important means by which fission yeast strikes a balance between the class F1 and class F2 paralog activities. This mode of regulation might be shared with other CSL-positive fungi, some of which are relevant to human disease and biotechnology

Role of molecular imaging in the management of patients affected by inflammatory bowel disease: State-of-the-art

To present the current state-of-the art of molecular imaging in the management of patients affected by inflammatory bowel disease (IBD)

On Some Geometric Structures Associated to a k-Symplectic Manifold

A canonical connection is attached to any k-symplectic manifold. We study the properties of this connection and its geometric applications to k-symplectic manifolds. In particular we prove that, under some natural assumption, any ksymplectic manifold admits an Ehresmann connection, discussing some corollaries of this result, and we find vanishing theorems for characteristic classes on a k-symplectic manifold.Comment: To appear on J. Phys. A: Math. Theo

eIF2α Kinases Regulate Development through the BzpR Transcription Factor in Dictyostelium discoideum

A major mechanism of translational regulation in response to a variety of stresses is mediated by phosphorylation of eIF2α to reduce delivery of initiator tRNAs to scanning ribosomes. For some mRNAs, often encoding a bZIP transcription factor, eIF2α phosphorylation leads to enhanced translation due to delayed reinitiation at upstream open reading frames. Dictyostelium cells possess at least three eIF2α kinases that regulate various portions of the starvation-induced developmental program. Cells possessing an eIF2α that cannot be phosphorylated (BS167) show abnormalities in growth and development. We sought to identify a bZIP protein in Dictyostelium whose production is controlled by the eIF2α regulatory system.Cells disrupted in the bzpR gene had similar developmental defects as BS167 cells, including small entities, stalk defects, and reduced spore viability. β-galactosidase production was used to examine translation from mRNA containing the bzpR 5' UTR. While protein production was readily apparent and regulated temporally and spatially in wild type cells, essentially no β-galactosidase was produced in developing BS167 cells even though the lacZ mRNA levels were the same as those in wild type cells. Also, no protein production was observed in strains lacking IfkA or IfkB eIF2α kinases. GFP fusions, with appropriate internal controls, were used to directly demonstrate that the bzpR 5' UTR, possessing 7 uORFs, suppressed translation by 12 fold. Suppression occurred even when all but one uORF was deleted, and translational suppression was removed when the ATG of the single uORF was mutated.The findings indicate that BzpR regulates aspects of the development program in Dictyostelium, serving as a downstream effector of eIF2α phosphorylation. Its production is temporally and spatially regulated by eIF2α phosphorylation by IfkA and IfkB and through the use of uORFs within the bzpR 5' UTR

Artemisinin-naphthoquine combination (ARCO™) therapy for uncomplicated falciparum malaria in adults of Papua New Guinea: A preliminary report on safety and efficacy

<p>Abstract</p> <p>Background</p> <p>The use of anti-malarial drug combinations with artemisinin or with one of its derivatives is now widely recommended to overcome drug resistance in falciparum as well as vivax malaria. The fixed oral dose artemisinin-naphthoquine combination (ANQ, ARCO™) is a newer artemisinin-based combination (ACT) therapy undergoing clinical assessment. A study was undertaken to assess the safety, efficacy and tolerability of ANQ combination in areas of multi-drug resistance to generate preliminary baseline data in adult population of Papua New Guinea.</p> <p>Methods</p> <p>The clinical assessment was an open-labeled, two-arm, randomized study comparing ANQ combination as a single dose regimen and three days regimen (10 mg/kg/day) of chloroquine plus single dose sulphadoxine-pyrimethamine (CQ+SP) for the treatment of uncomplicated falciparum malaria with 28 days follow-up in an adult population. The primary outcome measures for efficacy were day 1, 2, 3 7, 14 and 28-day cure rates. Secondary outcomes included parasite clearance time, fever clearance time, and gametocyte carriage. The main outcome measures for safety were incidences of post-treatment clinical and laboratory adverse events.</p> <p>Results</p> <p>Between June 2005 and July 2006, 130 patients with confirmed uncomplicated <it>P. falciparum </it>were randomly assigned to receive ANQ and CQ+SP, only 100 patients (51 in ANQ group and 49 in CQ+SP group) were evaluated for clinical and parasitological outcomes. All the patients treated with ANQ and CQ+SP showed adequate clinical and parasitological response with 28 days follow-up. The cure rate for ANQ on day 1, 2, 3, 7, 14, and 28 was 47%, 86%, 92%, 94%, 94% and 94%, respectively. Recrudescence account for 6%; all were cleared on day 21. For CQ+SP treated group the cure rates were 24%, 67%, 82%, 82%, 84% and 88%, respectively. Recrudescence accounted for 10%; all were cleared on day 28 except for one patient. Both regimens were well tolerated with no serious adverse events. The proportion of gametocyte carriers was higher in CQ+SP treated group than ANQ treatment (41% versus 12%; p < 0.05).</p> <p>Conclusion</p> <p>While these data are not themselves sufficient, it strongly suggests that the ANQ combination as a single dose administration is safe and effective for the treatment of uncomplicated <it>P. falciparum </it>malaria in the adult population of Papua New Guinea and deserves further clinical evaluation.</p

Single-photon-emitting radiopharmaceuticals for diagnostic applications

Radiopharmaceuticals contain a radionuclide and an agent to direct the radionuclide to a receptor, antigen, ionic pump, or other sites of interest. Some radiopharmaceuticals are simple, such as the ionic form of the radionuclide, while most radiopharmaceuticals have a complex chemical structure where the radionuclide provides a signal, indicating the site of localization of the carrier molecule. Common single-photon radiopharmaceuticals used for oncological diagnosis include the agents labeled with 99mTc such as 99mTcbisphosphonates (that accumulate at sites of bone mineral deposition), 99mTc-labeled colloids (that are used for lymphoscintigraphy and for imaging of the liver and spleen), 99mTc-hexakis-methoxy-isobutyl-isonitrile, and 99mTc-tetrofosmin (initially employed for myocardial perfusion imaging, and also used for localization of parathyroid adenomas and for identification of other malignant tumors). The most commonly used radiopharmaceuticals labeled with radioiodine (123I or 131I) include iodide itself (for localization of thyroid tissue) and the catecholamine analog metaiodobenzylguanidine (MIBG, for localizing pheochromocytoma and neuroblastoma). Thallium-201 chloride (201Tl) is used for myocardial perfusion imaging as well as tumor perfusion imaging, while 111In-pentetreotide detects overexpression of somatostatin receptors, especially in neuroendocrine tumors and in lesions arising from the neural crest, such as carcinoid, paragangliomas, and medullary thyroid carcinomas. 111In-capromab pendetide is a murine monoclonal antibody recognizing a transmembrane glycoprotein expressed by poorly differentiated and metastatic prostate adenocarcinomas. 67Ga-citrate receptors are overexpressed on membranes of both tumor and inflammatory cells

Preliminary clinical and radiologic outcome of matched patients with thoracoabdominal aortic aneurysms treated by low-profile vs standard profile branched aortic endografts

background: durability of low-profile branched aortic stent-grafts (LPSG) in the treatment of patients with thoracoabdominal aortic aneurysms (TAAA) remains unclear. objective of this study is to compare the outcomes of LPSG with standard profile branched aortic stent-grafts (SPSG). methods: between January 2016 and january 2020, 225 consecutive patients with TAAA were treated by branched endovascular aortic repair (BEVAR). twenty-four patients who were treated with a LPSG were compared to 24 patients who received SPSG as a control group. control patients were selected according to aneurysm size (maximum aneurysm diameter) and extension (Crawford classification) as well as availability of adequate preoperative and postoperative CT-angiograms at 24 months. the primary endpoint was ongoing clinical success defined as successful implantation and freedom from aneurysm- or procedure-related death, secondary intervention, type I or III endoleak, infection, thrombosis, aneurysm expansion or rupture and conversion. secondary endpoints were radiological changes of the branched endograft (migration, shortening, scoliosis, lordosis, and fracture). results: after a median follow-up of 22.6 (LPSG) and 26.2 months (SPSG), no significant difference was found in terms of technical success (100% in both groups), late mortality (4.2% vs 0%), aneurysm diameter increase (4.2% in both groups) and reinterventions (25% vs 37.5%). Infection, thrombosis, aneurysm expansion or rupture and conversion were not observed. aradiological analysis of aortic graft remodeling showed no fracture and no significant migration, shortening, scoliosis and lordosis of the LPSG (6.1 mm, 7.5 mm, 12.8° and 6.1°) compared to SPSG (3.9 mm, 5.1 mm, 7.9° and 5.6°) after 2 years. conclusion: the clinical and radiological findings of the present study showed no increased mortality and complications for the matched patients who underwent treatment with low-profile vs standard-profile BEVAR. this study provides preliminary evidence of safety and efficacy of low-profile branched endografts in patients with demanding iliac access vessels