Loss-of-function analysis of EphA receptors in retinotectal mapping

Peer reviewedPublisher PD

Influence of Oxygen at Atmospheric and High Pressure on the Developing Tooth Germ in Rat Embryos

Repeated exposure of pregnant rats to oxygen at high pressure (65 psi) twice a day for seven days increased the height of the tooth germ and ameloblastic layer of the embryo, but the width and odontoblastic layer were not changed. Exposure of pregnant rats to oxygen at atmospheric pressure stimulated the body growth of the embryo in utero.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68256/2/10.1177_00220345720510052501.pd

Differences in growth pattern of bone and incisor of rats exposed to O2 atmospheric and high pressure

Three groups of young rats (age 22 days) were exposed intermittently (49 times), over a period of 44 days, group 1 to O2 at atmospheric pressure (OAP), group 2 to O2 at high pressure (OHP) (60 psig) and the third to air at atmospheric pressure (AAP) as controls. The average food consumption for the AAP group was 18.85 g, for the OAP 17.55 g and for the OHP 17.07 g per rat per day. The change in the body weights of each of these groups was followed throughout the experiment which continued 13 days after the last exposures. Bone growth of the maxilla, mandible and femur diaphysis and incisor growth were not altered by the OAP exposures, but were decreased by the OHP exposures; incisor growth, however, was increased. Hardness of the bone (by Tukon Hardness Tester) was increased in the OAP and OHP exposures as compared with that of the AAP, but the hardness of the incisors was not altered.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34114/1/0000398.pd

Irreducible triangulations of surfaces with boundary

A triangulation of a surface is irreducible if no edge can be contracted to produce a triangulation of the same surface. In this paper, we investigate irreducible triangulations of surfaces with boundary. We prove that the number of vertices of an irreducible triangulation of a (possibly non-orientable) surface of genus g>=0 with b>=0 boundaries is O(g+b). So far, the result was known only for surfaces without boundary (b=0). While our technique yields a worse constant in the O(.) notation, the present proof is elementary, and simpler than the previous ones in the case of surfaces without boundary

Neuronal pentraxins mediate synaptic refinement in the developing visual system

Peer reviewedPublisher PD

Protostellar collapse: rotation and disk formation

We present some important conclusions from recent calculations pertaining to the collapse of rotating molecular cloud cores with axial symmetry, corresponding to evolution of young stellar objects through classes 0 and begin of class I. Three main issues have been addressed: (1) The typical timescale for building up a preplanetary disk - once more it turned out that it is of the order of one free-fall time which is decisively shorter than the widely assumed timescale related to the so-called 'inside-out collapse'; (2) Redistribution of angular momentum and the accompanying dissipation of kinetic (rotational) energy - together these processes govern the mechanical and thermal evolution of the protostellar core to a large extent; (3) The origin of calcium-aluminium-rich inclusions (CAIs) - due to the specific pattern of the accretion flow, material that has undergone substantial chemical and mineralogical modifications in the hot (exceeding 900 K) interior of the protostellar core may have a good chance to be advectively transported outward into the cooler remote parts (beyond 4 AU, say) of the growing disk and to survive there until it is incorporated into a meteoritic body.Comment: 4 pages, 4 figure

Milk consumption and the prepubertal somatotropic axis

© 2007 Rich-Edwards et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Super-critical Accretion Flows around Black Holes: Two-dimensional, Radiation-pressure-dominated Disks with Photon-trapping

The quasi-steady structure of super-critical accretion flows around a black hole is studied based on the two-dimensional radiation-hydrodynamical (2D-RHD) simulations. The super-critical flow is composed of two parts: the disk region and the outflow regions above and below the disk. Within the disk region the circular motion as well as the patchy density structure are observed, which is caused by Kelvin-Helmholtz instability and probably by convection. The mass-accretion rate decreases inward, roughly in proportion to the radius, and the remaining part of the disk material leaves the disk to form outflow because of strong radiation pressure force. We confirm that photon trapping plays an important role within the disk. Thus, matter can fall onto the black hole at a rate exceeding the Eddington rate. The emission is highly anisotropic and moderately collimated so that the apparent luminosity can exceed the Eddington luminosity by a factor of a few in the face-on view. The mass-accretion rate onto the black hole increases with increase of the absorption opacity (metalicity) of the accreting matter. This implies that the black hole tends to grow up faster in the metal rich regions as in starburst galaxies or star-forming regions.Comment: 16 pages, 12 figures, accepted for publication in ApJ (Volume 628, July 20, 2005 issue