Varied MR appearance of autism: Fifty-three pediatric patients having the full autistic syndrome

Fifty-three autism patients ranging in age from 2 to 22 yr with a mean age of 9 yr were evaluated by MR imaging over a 3-yr study period. Sagittal, axial, and coronal spin-echo and short TI inversion recovery scans were performed on a 0.5 Tesla (Picker Inc., Cleveland, OH) system. Results were compared to 32 control patients age range 1 to 17 yr, mean 8.5 yr. MR scans were evaluated by three neuroradiologists. Measurements of midsagittal vermian height and AP diameter were performed. Subjective estimates were made of ventricular size, amygdala size, fourth ventricular size, and vermian shape. Results were correlated with clinical presentation, course, and lab analyses by a pediatric neurologist. MR findings did not present a single pattern capable of predicting the presence or severity of autism. The constellation of MR findings in this group of 53 patients was highly variable, thus we advise caution in the interpretation of MR images in autistic patients. Autism is a heterogeneous disease entity containing different clinical subgroups, which do not manifest similar radiologic pictures.     

Relaxation of thiyl radicals as a measure of the probable timescale over which the missing fraction of muonium in water is lost

Muonium atoms produced in water react with thioacetamide (CH₃CSNH₂) to form a sulphur-centred (thiyl) free radical whose level-crossing-resonance from the CH₃-protons has been detected and analysed. Its amplitude increases with concentration below ∼10⁻² M but decreases at higher concentrations with a concommitant increase in linewidth. This is interpreted as indicating overlap with paramagnetic species from the muon track. It starts when the track is a few nanoseconds old.     

Dielectric properties of polymers based on hexafluoropropylene

Dielectric measurements have been made at frequencies from 10 Hz to 100 kHz and temperatures from 4 K to at least 300 K on a number of polymers containing units of hexafluoropropylene (HFP). These included copolymers of tetrafluoroethylene (TFE) and HFP, the homopolymer of HFP, elastomeric copolymers of HFP and vinylidene fluoride, and alternating copolymers of methyl vinyl ether with TFE and HFP. The effect of an ether linkage between the CF₃ group and the chain was also considered. Most of these polymers exhibited a main chain local mode relaxation near 228 K and a side group relaxation near 93 K.Dedicated to Professor Bernhard Wunderlich on the occasion of his 65th birthdayWe appreciate the helpful discussions with W. W. Schmiegel.     

High resolution spin labeled fatty acid: synthesis and EPR spectral characteristics

Stearic acid spin label substituted with deuterium in all positions and¹⁵N in the paramagnetic group has been synthesized and was found to display a 5.5 fold gain in sensitivity in the EPR spectrum and a 60% decrease in linewidth compared to the unmodified analog.     

The X-ray Structure of the Complex Dichloroorthovinyldiphenylarsineplatinum(II)

The X-ray structure analysis of the olefinic tertiary arsine complex dichloro$\text{ortho}$vinyldiphenylarsineplatinum(II) shows a square planar coordination geometry with the coordinated olefin making an angle of 83.6° with this plane.