The ossification of the metacarpal and phalangeal bones in human foetuses

An evaluation was made of the ossification level of the metacarpal and phalangeal bones in human foetuses of both sexes from the 4th to the 9th month of gestation. Our results indicate that ossification of phalangeal bones 1 to 5 always started at the distal end of the phalanx and endochondral ossification prevailed in the proximal phalanx of the thumb

Correspondence between HBT radii and the emission zone in non-central heavy ion collisions

In non-central collisions between ultra-relativistic heavy ions, the freeze-out distribution is anisotropic, and its major longitudinal axis may be tilted away from the beam direction. The shape and orientation of this distribution are particularly interesting, as they provide a snapshot of the evolving source and reflect the space-time aspect of anisotropic flow. Experimentally, this information is extracted by measuring pion HBT radii as a function of angle with respect to the reaction plane. Existing formulae relating the oscillations of the radii and the freezeout anisotropy are in principle only valid for Gaussian sources with no collective flow. With a realistic transport model of the collision, which generates flow and non-Gaussian sources, we find that these formulae approximately reflect the anisotropy of the freezeout distribution.Comment: 9 pages, 8 figure

Intensity interferometry of thermal photons from relativistic heavy ion collisions

Intensity interferometry of thermal photons, having transverse momenta $k_T \approx$ 0.1 -- 2.0 GeV, produced in relativistic collision of heavy nuclei is studied. It is seen to provide an accurate information about the temporal and spatial structure of the interacting system. The source dimensions and their $k_T$ dependence revealed by the photon interferometry, display a richness not seen in pion interferometry. We attribute this to difference in the source functions, the fact that photons come out from every stage of the collision and from every point in the system, and the fact that the rate of production of photons is different for the quark-gluon plasma, which dominates the early hot stage, and the hadronic matter which populates the last phase of the collision dynamics. The usefulness of this procedure is demonstrated by an application to collision of lead nuclei at the CERN SPS. Prediction for the transverse momentum dependence of the sizes for SPS, RHIC, and LHC energies are given.Comment: 16 pages, 11 figures. Added discussions and references. To appear in Phys. Rev.

Younger and older adults' cognitive and physical functioning in a virtual reality age manipulation

Objectives: Age group stereotypes (AGS), especially those targeting old age, affect an individual's behavior and long-term cognitive and physiological functioning. Conventional paradigms investigating the related mechanisms lack validity and stability. Our novel approach for the activation of self-relevant AGS uses a virtual reality (VR) ageing experience, measuring relevant effects on performance parameters. Methods: In a between-subjects experimental design, young participants embodied either a younger or older avatar in a 3D virtual environment to capture the effects on physical (Study 1; N = 68) and cognitive performance (Study 2; N = 45). In Study 3 (N = 117), the paradigm was applied to older participants. Results: For the younger participants, embodying older avatars was associated with declines in memory and physical performance when compared to the younger avatar age group. Furthermore, the manipulations' main effects were moderated by negative explicit AGS that matched the respective performance domains. For the older participants, we found no significant performance differences in the two domains investigated. Discussion: The experimental manipulation demonstrated an impact on relevant performance parameters on a motivational and strategic level, especially for strong performance-related AS, but for young participants only. Possible reasons and mechanisms for the differences in younger and older samples' results are discussed

Transport model analysis of particle correlations in relativistic heavy ion collisions at femtometer scales

The pion source as seen through HBT correlations at RHIC energies is investigated within the UrQMD approach. We find that the calculated transverse momentum, centrality, and system size dependence of the Pratt-HBT radii $R_L$ and $R_S$ are reasonably well in line with experimental data. The predicted $R_O$ values in central heavy ion collisions are larger as compared to experimental data. The corresponding quantity $\sqrt{R_O^{2}-R_S^{2}}$ of the pion emission source is somewhat larger than experimental estimates.Comment: 12 pages, 5 figures, to be published in PR