Search results for "Mathematical Computing"

Solution structure of R2Sn(IV)-β-N-Acetyl-Neuraminate (R=Me, Bu) complexes in D2O and DMSO-d6: experimental NMR and DFT computational study.

2007

Two diorganotin(IV)-NANA complexes (NANA (1) = beta-N-acetyl-Neuraminic Acid = 5-amino-3,5-dideoxy-D-glycero-beta-D-galactononulosic acid) with formula Me(2)Sn(iv)NANA (2) and Bu(2)Sn(IV)NANA (3) were synthesized and characterized by (1)H, (13)C and (119)Sn NMR spectroscopy, both in D(2)O and DMSO-d(6) solutions. The experimental data in DMSO suggested the monosaccharide bidentate chelation via O1 carboxylate and vicinal O2 alkoxide atoms, which, in D(2)O, can be dynamically extended to a third binding site (O8 atom) of the pendant chain. Coordination at the tin atom is discussed on the basis of experimental NMR data and DFT calculation.

A Novel Semi-Supervised Methodology for Extracting Tumor Type-Specific MRS Sources in Human Brain Data

2013

Background: The clinical investigation of human brain tumors often starts with a non-invasive imaging study, providing \ud information about the tumor extent and location, but little insight into the biochemistry of the analyzed tissue. Magnetic \ud Resonance Spectroscopy can complement imaging by supplying a metabolic fingerprint of the tissue. This study analyses \ud single-voxel magnetic resonance spectra, which represent signal information in the frequency domain. Given that a single \ud voxel may contain a heterogeneous mix of tissues, signal source identification is a relevant challenge for the problem of\ud tumor type classification from the spectroscopic signal.\ud Methodology/Princ…

EEG-related Functional MRI in Benign Childhood Epilepsy with Centrotemporal Spikes

2003

The localization of epileptic foci is an important issue in children with extratemporal epilepsies. However, the value of noninvasive methods such as the EEG-assisted functional magnetic resonance imaging (fMRI) has not been sufficiently investigated in children. As a model of extratemporal epilepsies, we studied 7 patients aged 5 to 12 (median 10) years with benign childhood epilepsy and centrotemporal (rolandic) spikes. Interictal spikes were recorded during the fMRI acquisition on a MR-compatible battery-powered digital EEG system with 16 channels. The fMRI sequences were correlated off-line with the EEG spikes and analyzed with the software Statistical Parametrical Mapping SPM99. The fM…

Pyrophosphate-mediated magnetic interactions in Cu(II) coordination complexes.

2010

The reaction in water of Cu(NO(3))(2)·2.5H(2)O with 2,2'-bipyridine (bipy), 1,10-phenanthroline (phen), or 1,10-phenanthroline-5-amine (phenam), and sodium pyrophosphate (Na(4)P(2)O(7)), at various pHs, afforded three new copper(II)-pyrophosphate complexes, namely, {[Cu(bipy)(cis-H(2)P(2)O(7))](2)}·3H(2)O (1a), {[Cu(phen)(H(2)O)](4)(HP(2)O(7))(2)}(ClO(4))(2)·4H(2)O (2), and {[Cu(2)(phenam)(2)(P(2)O(7))](2)·25H(2)O}(n) (3). A solvent free crystalline phase of 1a was also isolated with formula {[Cu(bipy)(trans-H(2)P(2)O(7))](2)} (1b), which can be regarded as a pseudo-polymorph of 1a. Single crystal X-ray analyses revealed these compounds to have uncommon molecular architectures, with 3 being…

Evolution of fitness in experimental populations of vesicular stomatitis virus

1996

Abstract The evolution of fitness in experimental clonal populations of vesicular stomatitis virus (VSV) has been compared under different genetic (fitness of initial clone) and demographic (population dynamics) regimes. In spite of the high genetic heterogeneity among replicates within experiments, there is a clear effect of population dynamics on the evolution of fitness. Those populations that went through strong periodic bottlenecks showed a decreased fitness in competition experiments with wild type. Conversely, mutant populations that were transferred under the dynamics of continuous population expansions increased their fitness when compared with the same wild type. The magnitude of …

Medical Biometry: Statistics or Black Magic?

2002

A mathematical approach to predicting the percutaneous absorption enhancing effect of sodium lauryl sulphate.

2003

A study has been made of the effect of sodium lauryl sulphate (SLS) at several concentrations from 0.24 to 5% (w/w) on skin permeability. Seven model drugs were selected for this study on the basis of their lipophilicity as represented by their logP(oct) values (from -0.95 to 4.2). Skin pre-treatment with aqueous solutions of SLS does not increase the permeability coefficient of the most lipophilic compounds (logP(oct)> or =3). For the other compounds assayed the increase in the permeability coefficients depends on the concentration of SLS used in the skin pre-treatment, and on the lipophilicity of the compounds tested.The correlation between the inverse of SLS efficacy as an enhancer (1/ER…

Computer-aided navigation in neurosurgery

2003

The article comprises three main parts: a historical review on navigation, the mathematical basics for calculation and the clinical applications of navigation devices. Main historical steps are described from the first idea till the realisation of the frame-based and frameless navigation devices including robots. In particular the idea of robots can be traced back to the Iliad of Homer, the first testimony of European literature over 2500 years ago. In the second part the mathematical calculation of the mapping between the navigation and the image space is demonstrated, including different registration modalities and error estimations. The error of the navigation has to be divided into the …

The radial artery is larger than the ulnar.

2003

The radial artery is presently widely used as a bypass graft for coronary artery reconstruction. However, the traditional opinion that the ulnar artery is the larger forearm artery has been questioned.The internal diameters of the radial and ulnar arteries were measured at the wrist in postmortem angiograms of 24 cadavers. Differences in mean values of variables between ulnar and radial arteries were analyzed using the Wilcoxon test.The mean diameter of the radial artery was 28% larger than that of the ulnar artery in the right arm (p0.001) and 26% larger in the left arm (p0.001). In the right arm the radial artery was dominant in 20 of 24 cadavers (83%), the ulnar artery in 3 of 24 (13%), …