Empirical evidence of the continuing improvement in cost efficiency of an endoscopic surveillance programme for gastric cancer in Singapore from 2004 to 2010

10.1186/1472-6963-13-139BMC Health Services Research131

Parallel Simulation of Compressible Atmospheric Flows: Bubble Convection

this paper we consider a semi-implicit treatment of the compressible equations proposed by Robert [10] to study vertical convection in the atmosphere at scales down to several metres. It is sometimes possible to further increase the time step and overcome the CourantFreidrichs -Lewy (CFL) stability bound with a semi-Lagrangian treatment of advection [9]. By integrating a characteristic equation backwards in time, the location of the departure point of a fluid particle in the Lagrangian frame of reference is found and then this particle is advected forward in time along the characteristic curve. The value at the foot of characteristic curve can be obtained by interpolation. In the more general setting of computational fluid dynamics, these schemes belong to the family of Eulerian-Lagrangian methods (ELM). Several authors, including Roache [7] and Oliveira and Baptista [6], note the equivalence of ELM's to Eulerian methods which have been translated or shifted by the advecting velocity. A general overview of their use in atmospheric models can be found in Staniforth and Cot'e [19]. In this paper, we focus on a parallel implementation of the semi-implicit, semi-Lagrangian scheme for the Euler equations. We have applied this scheme to the bubble convection problem [10] which is intended as a prototype for a more comprehensive atmospheric code. 3 2. Problem Formulatio

Gigantelline, gigantellinine and gigancrinine, cherylline- and crinine-type alkaloids isolated from Crinum jagus with anti-acetylcholinesterase activity

Three undescribed Amarylidaceae alkaloids, named gigantelline, gigantellinine and gigancrinine, were isolated from Crinum jagus (syn. = Crinum giganteum) collected in Senegal, together with the already known sanguinine, cherylline, lycorine, crinine, flexinine and the isoquinolinone derivative hippadine. Gigantelline, gigantellinine and gigancrinine were characterized as 4-(6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydro-isoquinolin-4-yl)-phenol, its 7-O-demethyl-5.-hydroxy-4.-methoxy derivative and 5,6a,7,7a,8a,9-hexahydro-6,9a-ethano[1,3]dioxolo[4,5j]oxireno[2,3-b]phenanthridin-9-ol, respectively, by using spectroscopic (1D and 2D H-1 and C-13 NMR and HRESIMS) and chemical methods. Their relative configuration was assigned by NOESY NMR spectra and NMR calculations, while the absolute configuration was assigned using electronic circular dichroism (ECD) experiments and calculations. Sanguinine, cherylline, crinine, flexinine, and the isoquinolinone hippadine, were isolated for the first time from C. jagus. Cherylline, gigantellinine, crinine, flexinine and sanguinine inhibited the activity of AChE in a dose-dependent manner, and inhibition by sanguinine was remarkably effective (IC50 = 1.83 +/- 0.01 mu M). Cherylline and hippadine showed weak cytotoxicity at 100 mu M

Shared And Distributed Memory Implementations Of The Canadian MC2 Model

The Mesoscale Compressible Community (MC2) model is an extension of a fully compressible limited area model developed by Monique Tanguay, Andre Robert and Rene Laprise in the mid-1980's. The model employs a three-timelevel semi-implicit, semi-Lagrangian time discretisation with modified terrain following Gal-Chen coordinates. The semi-implicit scheme results in an elliptic boundary value problem with first-order derivative terms in the vertical direction and thus the resulting discretised system of equations has a large sparse nonsymmetric coefficient matrix. The original alternating direction implicit (ADI) elliptic solver has been replaced with a flexible Generalised Minimum Residual (GMRES) Krylov method with variable preconditioning. We report on the performance of successive over relaxation (SOR) and vertical line relaxation (ADI) as parallel preconditioners to improve the convergence rate of GMRES. Parallelisation of the model for a distributed-memory computing environment has be..

Gigantelline, gigantellinine and gigancrinine, cherylline- and crinine-type alkaloids isolated from Crinum jagus with anti-acetylcholinesterase activity

Three undescribed Amarylidaceae alkaloids, named gigantelline, gigantellinine and gigancrinine, were isolated from Crinum jagus (syn. = Crinum giganteum) collected in Senegal, together with the already known sanguinine, cherylline, lycorine, crinine, flexinine and the isoquinolinone derivative hippadine. Gigantelline, gigantellinine and gigancrinine were characterized as 4-(6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydro-isoquinolin-4-yl)-phenol, its 7-O-demethyl-5ꞌ-hydroxy-4ꞌ-methoxy derivative and 5,6a,7,7a,8a,9-hexahydro-6,9a-ethano[1,3]dioxolo[4,5-j]oxireno[2,3-b]phenanthridin-9-ol, respectively, by using spectroscopic (1D and 2D 1H and 13C NMR and HRESIMS) and chemical methods. Their relative configuration was assigned by NOESY NMR spectra and NMR calculations, while the absolute configuration was assigned using electronic circular dichroism (ECD) experiments and calculations. Sanguinine, cherylline, crinine, flexinine, and the isoquinolinone hippadine, were isolated for the first time from C. jagus. Cherylline, gigantellinine, crinine, flexinine and sanguinine inhibited the activity of AChE in a dose-dependent manner, and inhibition by sanguinine was remarkably effective (IC50 = 1.83 ± 0.01 μM). Cherylline and hippadine showed weak cytotoxicity at 100 μM

Isolation and biological characterization of homoisoflavanoids and the alkylamide n‐p‐coumaroyltyramine from crinum biflorum rottb., an amaryllidaceae species collected in Senegal

Crinum biflorum Rottb. (syn. Crinum distichum) is an Amaryllidaceae plant used in African traditional medicine but very few studies have been performed on this species from a chemical and applicative point of view. Bulbs of C. biflorum, collected in Senegal, were extracted with ethanol by Soxhlet and the corresponding organic extract was purified using chromatographic methods. The pure compounds were chemically characterized by spectroscopic techniques (1D and 2D1H and13C NMR, HR MS and ECD) and X‐ray analysis. Four homoisoflavonoids (1–4) and one alkylamide (5) were isolated and characterized as 5,6,7‐trimethoxy‐3‐(4‐hydroxybenzyl)chroman‐4‐one (1), as 3‐hydroxy‐ 5,6,7‐trimethoxy‐3‐(4‐hydroxybenzyl)chroman‐4‐one (2), as 3‐hydroxy‐5,6,7‐trimethoxy‐3‐(4‐methox-ybenzyl)chroman‐4‐one (3) and as 5,6,7‐trimethoxy‐3‐(4‐methoxybenzyl)chroman‐4‐one (4), and the alkylamide as (E)‐N‐(4‐hydroxyphenethyl)‐3‐(4‐hydroxyphenyl)acrylamide (5), commonly named N‐ p‐coumaroyltyramine. The relative configuration of compound 1 was verified thanks to the X‐ray analysis which also allowed us to confirm its racemic nature. The absolute configurations of compounds 2 and 3 were assigned by comparing their ECD spectra with those previously reported for urgineanins A and B. Flavanoids 1, 3 and 4 showed promising anticancer properties being cytotoxic at low mi-cromolar concentrations towards HeLa and A431 human cancer cell lines. The N‐p‐coumaroyltyra-mine (5) was selectively toxic to A431 and HeLa cancer cells while it protected immortalized HaCaT cells against oxidative stress induced by hydrogen peroxide. Compounds 1–4 also inhibited acetylcho-linesterase activity with compound 3 being the most potent. The anti‐amylase and the strong anti-glucosidase activity of compound 5 were confirmed. Our results show that C. biflorum produces compounds of therapeutic interest with anti‐diabetic, anti‐tumoral and anti‐acetylcholinesterase proper-ties