Sl00a8 in development.

S100 proteins are a family of Ca2+ binding EF-hand proteins. S100A8 is a cytosolic protein expressed in myeloid cells and epithelia where it forms a stable heterodimer with another SI00 protein family member, S100A9. The S100A9 null mouse is viable and has no gross defect whereas the S100A8 null mouse is embryonic lethal. It was originally proposed that the S100A8 null mouse is lethal at E 9.0 in development due to lack of expression at E 6.5 in ectoplacental cone cells. This thesis shows that the S100A8 null phenotype is more complex than originally thought. S100A8 has a role in preimplantation development, which is previously unstudied. A small number of S100A8 null embryos survive to blastocyst but none survive implantation showing fatal compromise of S100A8 null embryos early in development. This thesis presents evidence that this lethality presents between fertilisation and E 2.5 of development. S100A8 also has a role in the murine decidua after implantation possibly key to normal murine development. S100A8 mRNA is highly expressed in maternal decidua yet S100A8 protein is not highly expressed. Foetal yolk sac cells do not express S100A8 mRNA yet they do stain positively for S100A8 protein. This thesis proposes that S100A8 protein is generated in the murine decidua and exported to the foetus where haematopoietic cells present the protein. The S100A8 protein has been shown to be expressed and stable independently of its myeloid partner, S100A9. These observations explain the discrepancy between the two SI00 null mouse phenotypes and add new insight to the S100A8 null phenotype

Demonstration by immunoblotting of heterogeneity in the autoantibody response directed against fat cells in Graves' disease

AbstractGuinea pig fat cell membranes (FCM) have been widely used in preference to thyroid membranes as a source of TSH receptors to investigate TSH receptor antibodies in Graves' disease, because FCM are ostensibly free of other thyroid antigens. However, by FCM immunoblotting we have found: (i) 8 of 10 normal sera bound to determinants at 38 and 190 kDa; (ii) 17 other determinants were recognised by 60% of Graves' or Hashimoto sera and by 20% of normal sera; (iii) three determinants at 65–90 kDa were recognised by 5 of 13 Graves' but by none of the normal or Hashimoto sera; and (iv) none of the determinants recognised appeared to be related to the TSH receptor

A New Dimension to Relative Age Effects: Constant Year Effects in German Youth Handball

In this manuscript we argue for a broader use of the term ‘relative age effect’ due to the influence of varying development policies on the development of sport expertise. Two studies are presented on basis of data from Schorer, et al. [1]. The first showed clear ‘constant year effects’ in the German handball talent development system. A shift in year groupings for the female athletes resulted in a clear shift of birth year patterns. In the second study we investigated whether the constant year effect in the national talent development system carried over to professional handball. No patterns were observable. Together both studies show that a differentiation of varying effects that often happen simultaneously is necessary to understand the secondary mechanisms behind the development of sport expertise.<br/

The Quark Propagator from the Dyson-Schwinger Equations: I. the Chiral Solution

Within the framework of the Dyson-Schwinger equations in the axial gauge, we study the effect that non-perturbative glue has on the quark propagator. We show that Ward-Takahashi identities, combined with the requirement of matching perturbative QCD at high momentum transfer, guarantee the multiplicative renormalisability of the answer. Technically, the matching with perturbation theory is accomplished by the introduction of a transverse part to the quark-gluon vertex. We show that this transverse vertex is crucial for chiral symmetry breaking, and that massless solutions exist below a critical value of the strong coupling constant. Using the gluon propagator that we previously calculated, we obtain small corrections to the quark propagator, which keeps a pole at the origin in the chiral phase.Comment: 21 pages, 6 figures; McGill/94-24, SHEP 93/94-26 We generalise our results by showing that they are not sensitive to the specific choice that we make for the transverse vertex. We illustrate that fact in two new figure

On laser vibrometry of rotating targets: effects of torsional and in-plane motion

Vibration measurements on rotating surfaces are often referred to in ·the commercial literature as a major application of laser Doppler vibration transducers. This paper examines such use of these instruments and shows how the presence of a velocity component due to the rotation itself leads to spurious measurement dependence on both torsional vibration and motion perpendicular to the line of incidence of the laser beam. In addition, the scale of this dependence increases with both rotation speed and perpendicular distance between the line of incidence and a parallel line through the centre of rotation. These phenomena are investigated theoretically and excellent agreement is found when compared with experimental data. Two solutions are suggested; the first involves careful alignment of the laser beam whereas the second requires two simultaneous, orthogonal measurements to be made. If neither method is adopted it is entirely conceivable that the intended solid body vibration measurement may be masked at many frequencies of interest

Laser vibrometry: pseudo-vibrations

The application of Laser Doppler Velocimetry (LDV) to the measurement of normal-to-surface vibration of a solid surface is now established as a technique complementary to the use of an accelerometer. Several practical systems have been developed and a number are now commercially available. Each velocirneter relies on the same principle of operation, namely the detection of a Doppler shift, fD, in the light scattered from a vibrating target. Fig. 1 shows a typical vibrometer arrangement. Since the photodetector cannot respond quickly enough to detect the light frequency directly, scattered light from the vibrating surface is mixed with a reference beam and heterodyned on the detector surface. In addition, in order to resolve the sign of the vibration velocity, it is necessary to pre-shift the reference beam by a known amount, fR, resulting in an optical beat at the detector of frequency (fR ± fD). An appropriate Doppler signal processor then demodulates the detector signal to produce a time-resolved analogue of the target vibration velocity (in the direction of the incident beam). Systems differ in the method adopted to produce the reference beam frequency shift. Bragg cells [1], diffraction gratings [2] rotating scattering discs [3] and frequency modulation of the laser beam itself [4] have all been used successfully... (continues)

Gauge conditions for binary black hole puncture data based on an approximate helical Killing vector

We show that puncture data for quasicircular binary black hole orbits allow a special gauge choice that realizes some of the necessary conditions for the existence of an approximate helical Killing vector field. Introducing free parameters for the lapse at the punctures we can satisfy the condition that the Komar and ADM mass agree at spatial infinity. Several other conditions for an approximate Killing vector are then automatically satisfied, and the 3-metric evolves on a timescale smaller than the orbital timescale. The time derivative of the extrinsic curvature however remains significant. Nevertheless, quasicircular puncture data are not as far from possessing a helical Killing vector as one might have expected.Comment: 11 pages, 6 figures, 2 table