Patient-specific RF safety assessment in MRI: Progress in creating surface-based human head and shoulder models

The interaction of electromagnetic (EM) fields with the human body during magnetic resonance imaging (MRI) is complex and subject specific. MRI radiofrequency (RF) coil performance and safety assessment typically includes numerical EM simulations with a set of human body models. The dimensions of mesh elements used for discretization of the EM simulation domain must be adequate for correct representation of the MRI coil elements, different types of human tissue, and wires and electrodes of additional devices. Examples of such devices include those used during electroencephalography, transcranial magnetic stimulation, and transcranial direct current stimulation, which record complementary information or manipulate brain states during MRI measurement. The electrical contact within and between tissues, as well as between an electrode and the skin, must also be preserved. These requirements can be fulfilled with anatomically correct surface-based human models and EM solvers based on unstructured meshes. Here, we report (i) our workflow used to generate the surface meshes of a head and torso model from the segmented AustinMan dataset, (ii) head and torso model mesh optimization for three-dimensional EM simulation in ANSYS HFSS, and (iii) several case studies of MRI RF coil performance and safety assessment

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

cber gest\uf6rtes L\ue4ngenwachstum nach Ausschalten des Subcommissuralorgans bei Larven von Xenopus laevis

Volume: 81Start Page: 678End Page: 68

Structural dynamics of GaN microcrystals in evolutionary selection selective area growth probed by X-ray microdiffraction

A method to grow high quality, single crystalline semiconductor material irrespective of the substrate would allow a cost-effective improvement to functionality and performance of optoelectronic devices. Recently, a novel type of substrate-insensitive growth process called Evolutionary Selection Selective Area Growth (ES-SAG) has been proposed. Here we report the use of X-ray microdiffraction to study the structural properties of GaN microcrystals grown by ES-SAG. Utilizing high resolution in both direct and reciprocal spaces, we have unraveled structural dynamics of GaN microcrystals in growth structures of different dimensions. It has been found that the geometric proportions of the growth constrictions play an important role: 2.6â.Î 1/4m and 4.5â.Î 1/4m wide growth tunnels favor the evolutionary selection mechanism, contrary to the case of 8.6â.Î 1/4m growth tunnels. It was also found that GaN microcrystal ensembles are dominated by slight tensile strain irrespective of growth tunnel shape

Antimicrobial resistance data on 16,756 Streptococcus pneumoniae isolates in 1999: A pan-regional multicenter surveillance study in France

International audienc

Évolution de la sensibilité de Streptococcus pneumoniae aux antibiotiques : résultats de l'observatoire du pneumocoque Alsace (année 2005) Evolution of antibiotic resistance of Streptococcus pneumoniae: results of Alsace observatory in 2005 Author's perso

Résumé But de l'étude. -Entre le 1 er janvier et le 31 décembre 2005, les participants à l'Observatoire régional du pneumocoque (ORP) Alsace (un centre hospitalier universitaire, sept centres hospitaliers non universitaires et 12 laboratoires privés) ont collecté 232 souches supposées pathogènes et non redondantes de Streptococcus pneumoniae pour étudier leur sensibilité vis-à-vis des bêtalactamines. Méthode. -Les concentrations minimales inhibitrices (CMI) de la pénicilline G, de l'amoxicilline et du céfotaxime ont été déterminées par la méthode E-test et par la méthode de dilution en milieu gélosé (Steers). Les résultats ont été interprétés selon les recommandations du CA-SFM. Les sensibilités à d'autres molécules ont été étudiées. Abstract Objectives. -Between 1st January 2005 and 31st December 2005, 232 strains of Streptococcus pneumoniae were collected in the Alsace county from participating laboratories (one from university hospital, 7 from general hospitals and 12 private laboratories) to assess their susceptibility to penicillin and evaluated serogroups of strains. Method. -The coordinating centre performed MICs by the reference agar dilution test, interpreted according to CA-SFM breakpoints. Others antibiotics (erythromycin, cotrimoxazole, tetracycline…) were tested by agar diffusion, ATB-PNEUMO gallery or VITEK gallery (BioMérieux, France) by each participating laboratory. Data were processed, using 4th dimension software. Results. -Strains were collected from 151 blood samples, 38 ear pus, 11 cerebrospinal fluids, 8 pleural liquids and 24 representative pulmonary samples. The prevalence of pneumococci with decreased susceptibility to penicillin G (PDSP) is 35.1% (pulmonary samples excluded). The rate of PNSP decreases for all types of samples compared with other years of surveillance 2003 (44.0%). The rate of blood samples decreases for first time between the creation of Pneumococcal Observatory. The high-level resistance tend to decrease and began low. The PDSP are rather resistant to erythromycin, cotrimoxazole and fosfomycin. Among the PDSP, the most prevalent serotypes were 14, 19, 6 and 9. Conclusion. -Among pneumococcal strains, the rate of PDSP tend however to decrease in 2005 compared with 2003. The rate stays inferior to the observed rates in other French counties where the same decreasing is described