A comparison of temporal measures of speech using spectrograms and digital oscillograms

To determine whether any systematic differences occur as a result of using spectrograms versus digital oscillograms to make durational measurements, a number of temporal features (e.g., voice onset time, vowel duration, and consonant closure duration) for 3 speakers were independently measured by 2 different investigators. Both experimenters measured the same intervals with conventional spectrograms and with digital oscillograms, separated by at least a 2-week interval. Oscillograms tended to reveal slightly longer vowel durations and more voicing during consonant closure, while spectrograms evidenced slightly longer consonant closure durations. In general, variations between the two types of instrumentation were no more than 8 to 10 ms and are, therefore, of primary consequence only for studies in which quite small temporal differences are critical.     

Structural Features of a Close Homologue of L1 (CHL1)in the Mouse: A New Member of the L1 Family of Neural Recognition Molecules

We have identified a close homologue of L1 (CHL1) in the mouse. CHL1 comprises an N-terminal signal sequence, six immunoglobulin (Ig)-like domains, 4.5 fibronectin type III (FN)-like repeats, a transmembrane domain and a C-terminal, most likely intracellular domain of ?100 amino acids. CHL1 is most similar in its extracellular domain to chicken Ng-CAM (?40% amino acid identity), followed by mouse L1, chicken neurofascin, chicken Nr-CAM, Drosophila neuroglian and zebrafish L1.l (37-28% amino acid identity), and mouse F3, rat TAG-1 and rat BIG-1 (?27% amino acid identity). The similarity with other members of the Ig superfamily [e.g. neural cell adhesion molecule (N-CAM), DCC, HLAR, rse] is 16-11%. The intracellular domain is most similar to mouse and chicken Nr-CAM, mouse and rat neurofascin (?60% amino acid identity) followed by chicken neurofascin and Ng-CAM, Drosophila neuroglian and zebrafish L1.l and L1.2 (?40% amino acid identity). Besides the high overall homology and conserved modular structure among previously recognized members of the L1 family (mouse/human L1/rat NILE; chicken Ng-CAM; chicken/mouse Nr-CAM; Drosphila neuroglian; zebrafish L1.l and L1.2; chicken/mouse neurofascin/rat ankyrin-binding glycoprotein), criteria characteristic of L1 were identified with regard to the number of amino acids between positions of conserved amino acid residues defining distances within and between two adjacent Ig-like domains and FN-like repeats. These show a collinearity in the six Ig-like domains and four adjacent FN-like repeats that is remarkably conserved between L1 and molecules containing these modules (designated the L1 family cassette), including the GPI-linked forms of the F3 subgroup (mouse F3/chicken F1l/human CNTN1; rat BIG-l/mouse PANG; rat TAG-l/mouse TAX-l/chicken axonin-1). The colorectal cancer molecule (DCC), previously introduced as an N-CAM-like molecule, conforms to the L1 family cassette. Other structural features of CHL l shared between members of the L1 family are a high degree of N-glycosidically linked carbohydrates (?20% of its molecular mass), which include the HNK-1 carbohydrate structure, and a pattern of protein fragments comprising a major 185 kDa band and smaller fragments of 165 and 125 kDa. As for the other L1 family members, predominant expression of CHL l is observed in the nervous system and at later developmental stages. In the central nervous system CHL l is expressed by neurons, but, in contrast to L1, also by glial cells. Our findings suggest a common ancestral L1-like molecule which evolved via gene duplication to generate a diversity of structurally and functionally distinct yet similar molecules.     

Quantitative magnetic resonance imaging of capillary water permeability and regional blood volume with an intravascular MR contrast agent

A novel method is presented to simultaneously measure the permeability surface area product of water (PS), also known as capillary diffusion capacity, and the regional blood volume (RBV). It is based on magnetic resonance imaging of the longitudinal relaxation times of tissue and blood at different concentrations of an intravascular MR contrast agent. PS and RBV were measured in vivo in different regions of the brain and the skeletal muscle of the rat. The average PS values (n = 5) obtained in cerebral cortex, corpus callosum, hippocampus, thalamus, jaw muscle, and tongue muscle were 3.31 ± 0.20, 1.81 ± 0.25, 3.37 ± 0.36, 3.68 ± 0.44, 10.6 ± 1.1, and 14.1 ± 2.51 ml ± min^?1 ± g^?1, respectively. The corresponding average RBV values were 1.63 ± 0.18,1.22 ± 0.25,3.30 ± 0.37, 3.03 ± 0.36, 1.66 ± 0.30, and 1.38 ± 0.33 ml ± 100g^?1. These results are in good agreement with previously reported literature values obtained by means of autoradiography.     

Introduction of an aspiration-irrigation-reflow system with a special handle for extracapsular cataract operation

A new irrigation/aspiration system consisting of an electromechanical switch and a special handle is described. The switch mechanisms acts on a tube system connected to the handle, enabling the anterior chamber to be refilled immediately via the aspiration opening, so that collapse is impossible. A further advantage is that fluid exchange is minimized, because aspiration only occurs when the pedal switch is operated. When the pedal is released the fluid is spontaneously flushed back via the aspiration opening. This results in a significant reduction in capsular and iris complications. Thanks to the special handle the fluid flushed back is practically free of lens particles.     

The close homologue of the neural adhesion molecule L1 (CHL1): patterns of expression and promotion of neurite outgrowth by heterophilic interactions

The close homologue of L1 (CHL1), a member of the L1 family of neural adhesion molecules, is first expressed at times of neurite outgrowth during brain development, and is detectable in subpopulations of neurons, astrocytes, oligodendrocyte precursors and Schwann cells of the mouse and rat. Aggregation assays with CHL1-transfected cells show that CHL1 does not promote homophilic adhesion or does it mediate heterophilic adhesion with L1. CHL1 promotes neurite outgrowth by hippocampal and small cerebellar neurons in substrate-bound and soluble form. The observation that CHL1 and L1 show overlapping, but also distinct patterns of synthesis in neurons and glia, suggests differential effects of L1-like molecules on neurite outgrowth.