Early tertiary elephant-shrews from Egypt and the origin of the Macroscelidea

Recent expeditions to the Fayum Depression, Egypt, have made possible the discovery of mandibles and a maxilla of a new genus and species of late Eocene elephant-shrew as well as initial evidence of the upper dentition of the early Oligocene taxon Metoldobotes. These fossils demonstrate that macroscelideans underwent a significant radiation in the Early Tertiary of Africa. Two new subfamilies are recognized and described. These Tertiary macroscelideans are the most primitive elephant-shrews known and indicate that previous hypotheses of a close phylogenetic relationship between macroscelideans and either lagomorphs, erinaceotans, or tree-shrews are unlikely. Rather, the dental anatomy of the Fayum macroscelideans provides evidence for a derivation of the order from within the Condylarthra.     

Experimental measurement of impulse response and noise for an emission computed tomography system

Experimental studies have been made of the impulse response and noise characteristics of a tomographic system using a gamma camera. Fourier transform, deconvolution and iterative methods have been used with a CDC 6600 computer to reconstruct images from data obtained for various experimental arrangements of sources in a cylindrical phantom. It is shown that with an appropriate attenuation correction the impulse response in the reconstruction is substantially constant, independent of the position of the source in the phantom and that the reconstruction technique used is of secondary importance.The resolution obtained for the impulse response and the relative noise level throughout the non image part of the reconstructions is shown for different experimental situations.The measured variance in the reconstruction of an extended uniform activity source was found to be somewhat below the theoretical value except at high count densities (above 1,000 counts per image element) where the limit of accuracy of the reconstruction is shown to be imposed by the variation in the camera sensitivity over the field of view.     

The neuro-ophthalmology of systemic lupus erythematosus

Conclusion Experience with many patients with SLE and a review of the literature indicate that neuro-ophthalmic abnormalities are frequently found in patients with SLE.The optic disc may become swollen in patients with SLE either as a result of local retinal lesions or secondary to increased intracranial pressure. Some of the cases with increased intracranial pressure resemble the entity of pseudotumor cerebri.Patients with SLE may develop an optic neuropathy. The pathogenesis appears either to be demyelinative or secondary to parenchymal microinfarcts. Some of the patients develop a clinical syndrome identical to Devic's desease. The response to corticosteroids is unpredictable. Acute anterior ischemic optic neuropathy is rare in patients with SLE.Homonymous hemianopias may occur in isolation or in association with hemiplegia, aphasia or hemisensory defects. Both formed and unformed visual hallucinations are commonly encountered, and patients may have transient amaurosis or geniculocalcarine (cortical) blindness. Visual hallucinations identical to those seen in migraine, and vascular headaches appear to be more common in patients with SLE than among controls.Diplopia occurs in patients with SLE most often as a transient phenomenon associated with vertigo. Transient ptosis may also occur. These findings, like the transient bilateral amaurosis, suggest the picture of insufficiency in the vertebrobasilar system. Diplopia may also occur from fixed lesions in the brain stem and several instances of internuclear ophthalmoplegia have been recognized. If ophthalmoplegia or ptosis develop in a patient with SLE it should suggest the possibility that the patient has myasthenia gravis which occurs with unusually high frequency among patients with SLE.     

Insights from semantic dementia on the relationship between episodic and semantic memory

An influential theory of long-term memory, in which new episodic learning is dependent upon the integrity of semantic memory, predicts that a double dissociation between episodic and semantic memory is not possible in new learning. Contrary to this view, we found, in two separate experiments, that patients with impaired semantic memory showed relatively preserved performance on tests of recognition memory if the stimuli were perceptually identical between learning and test. A significant effect of semantic memory was only seen when a perceptual manipulation was introduced in the episodic task. To account for these findings, we propose a revision to current models of long-term memory, in which sensory/perceptual information and semantic memory work in concert to support new learning.     

Educational progress,behaviour, and motor skills at 10 years in early treated congenital hypothyroidism

AIM—To assess educational attainments, behaviour, and motor skills at 10 years of age in a group of children with congenital hypothyroidism identified by neonatal screening.SUBJECTS—59 children with congenital hypothyroidism born in 1978-81, 31 cases with pretreatment thyroxine (T4) values of 40 nmol/l or below (group I) and 28 less severe cases with T4 values over 40 nmol/l (group II), together with 59 classroom control children matched for age, sex, social class, and main language spoken at home.METHODS—The Neale analysis of reading ability; the child health and education study written test of mathematics; Rutter behaviour questionnaires for parents and teachers; the Oseretsky test of motor proficiency (short form).RESULTS—On all measures the congenital hypothyroidism children in group I had less satisfactory scores for educational attainments, behaviour, and motor skills than those in group II and controls. For reading the differences were small and did not reach statistical significance, but the deficits in mathematics and total motor skills were statistically significant (p < 0.01). There were more striking and statistically significant differences in behaviour scores, particularly with respect to attentional difficulties. Although less striking, these were also apparent in the group II children with mild hypothyroidism.CONCLUSIONS—At the age of 10 years severe congenital hypothyroidism is associated with some mild impairment in educational and motor attainments. Behaviour problems are also common, even in some children with less severe congenital hypothyroidism.     

Zeitschriften

Ohne Zusammenfassung     

Strahlenwirkungen

Ohne Zusammenfassung     

Strahlenwirkungen

Ohne Zusammenfassung