			Home About us Contact

Method Only (method + only)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Comparing MEG and fMRI views to naming actions and objects

HUMAN BRAIN MAPPING, Issue 6 2009
Mia Liljeström
Abstract Most neuroimaging studies are performed using one imaging method only, either functional magnetic resonance imaging (fMRI), electroencephalography (EEG), or magnetoencephalography (MEG). Information on both location and timing has been sought by recording fMRI and EEG, simultaneously, or MEG and fMRI in separate sessions. Such approaches assume similar active areas whether detected via hemodynamic or electrophysiological signatures. Direct comparisons, after independent analysis of data from each imaging modality, have been conducted primarily on low-level sensory processing. Here, we report MEG (timing and location) and fMRI (location) results in 11 subjects when they named pictures that depicted an action or an object. The experimental design was exactly the same for the two imaging modalities. The MEG data were analyzed with two standard approaches: a set of equivalent current dipoles and a distributed minimum norm estimate. The fMRI blood-oxygen-level dependent (BOLD) data were subjected to the usual random-effect contrast analysis. At the group level, MEG and fMRI data showed fairly good convergence, with both overall activation patterns and task effects localizing to comparable cortical regions. There were some systematic discrepancies, however, and the correspondence was less compelling in the individual subjects. The present analysis should be helpful in reconciling results of fMRI and MEG studies on high-level cognitive functions. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc. [source]

Immediate Clinical Outcome after Prolonged Periods of Brain Protection: Retrospective Comparison of Hypothermic Circulatory Arrest, Retrograde, and Antegrade Perfusion

JOURNAL OF CARDIAC SURGERY, Issue 5 2009
Anil Z. Apaydin M.D.
Methods: Between 1993 and 2006, 339 patients underwent proximal aortic operations using a period of cerebral protection. Among these, 161 patients (mean age of 55 ± 12 years) who required cerebral protection longer than 25 minutes were included in the analysis. Ascending aorta with or without root was replaced in all patients. In addition, total arch replacement was performed in 36 patients. All patients were cooled to rectal temperature of 16 °C. Hypothermic circulatory arrest without adjunctive perfusion was used in 48 patients. Retrograde or antegrade cerebral perfusion was added in 94 and 19 patients, respectively. The mean duration of total cerebral protection was 42 ± 17 minutes. Results: Overall mortality was 15.5% (25/161) and did not differ among the perfusion groups. There was no difference in the incidence of overall neurological events, temporary neurological dysfunction, or major stroke among the groups. Multivariate analysis revealed that transfusion of >3 units of blood (p < 0.03) was an incremental risk factor for mortality. History of hypertension (p < 0.03), coexisting systemic diseases (p < 0.005), and transfusion of >3 units of blood (p < 0.04) were predictors of temporary neurological dysfunction. Conclusion: In proximal aortic operations requiring prolonged periods of cerebral protection, the mortality and neurological morbidity are not determined by the type of cerebral protection method only. Factors like hypertension and diabetes may play a role in the development of temporary neurological dysfunction. [source]

Evaluation of a modified IAT-gel with polyethylenglycol (PEG) addition method for red blood cell antibody identification

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 3 2004
L. Gustafsson
Abstract We aimed to evaluate whether a PEG-IAT method, modified for gel technique, could replace the two-stage enzyme method for routine identification of red blood cell (RBC) antibodies. A total of 161 selected patient samples were analyzed with the two-stage enzyme tube technique and the PEG-IAT in gel techniques. In 65 samples, identical antibody results were obtained by the two methods. An additional 28 antibodies were identified by either the PEG-IAT gel method or the enzyme method. Twenty antibodies were identified by the PEG-IAT gel method only (12 Rh antibodies, four anti-Kell, two anti-Fya, two anti-Jka), and eight antibodies by the enzyme method only (four Rh antibodies, one anti-K, one anti-Jka, two anti-Lea). The results in the remaining 68 samples were judged as nonspecific reactions, which were more common when the enzyme method was used. We concluded that the PEG-IAT in gel method identifies more RBC antibodies with less nonspecific reactions than the two-stage enzyme technique. However, no single method detected all clinical significant RBC antibodies. J. Clin. Lab. Anal. 18:165,169, 2004. © 2004 Wiley-Liss, Inc. [source]

Fast series resistance imaging for silicon solar cells using electroluminescence

PHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 7-8 2009
Jonas Haunschild
Abstract We introduce a fast and easy to apply method for determining the local series resistance of standard silicon solar cells. For this method only two electroluminescence images taken at different voltages are needed. From these two images, the local voltage and the local current density through the device can be calculated. Knowing these parameters for each pixel yields the local series resistance. By calculating the cell's dark saturation current from the lower voltage image, the method also works with multicrystalline material. We show images, acquired in only 300 ms and compare them with other luminescence based series resistance images. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]