Rest Frame Optical Spectra of Lyman Break Galaxies: Other Lensing Arcs around MS1512-cB58

We have obtained near-infrared spectra of two images of the galaxy at z=2.72 which is gravitationally lensed by the foreground cluster MS1512+36. The brighter arc, cB58, is an image of only the nucleus and the southern half of the background galaxy, while the fainter image, A2, encompasses the entire background galaxy. Thus the gravitational lensing provides spatial resolution on a smaller scale than is routinely available by other methods. Our observations indicate no evidence for any systematic rotational velocity gradient across the face of this galaxy. The nucleus and outer regions of the galaxy do not differ in their gas reddening or excitation level, based on the identical Hα/5007 ratios. cB58 (which is more dominated by the nucleus) has relatively stronger continuum emission, perhaps because of a higher ratio of old to young stars, compared to the outer parts of the galaxy. A second emission line source, denoted as K1, at a slightly lower redshift was serendipitously detected in the slit. It appears to be the gravitationally lensed image of another background galaxy in the same group as cB58

Older drivers: Crash involvement rates and causes

This report presents an analysis of the claims that older drivers are over-represented in road crashes and an examination of the nature of the ‘older driver problem’ in so far as it exists. Four different types of crash rates (crash numbers, crashes per head of population, crashes per licensed driver, crashes per distance driven) are considered, with emphasis placed on problems in interpretation of the various crash rates and what information can be derived from each of them. It is concluded that the crash rates of most importance are total crash numbers and crashes per licensed driver, neither of which were found to feature an over-representation of older drivers. Also addressed in the report is the question of whether the increase in crash rates per distance driven might be a phenomenon associated with older drivers as a whole, or one associated with specific subgroups of older drivers whilst the remainder maintain the relatively low crash rates of middle-aged drivers. Although there are arguments to support the claim that there are high risk subgroups of older drivers, it is nevertheless concluded that high risk older drivers cannot be identified in mass crash data. A third section of the report contains an analysis of a sample of crashes involving older drivers that were investigated as part of an in-depth study into rural road crashes. The factors other than the driver which contributed to the occurrence of the crashes are discussed, illustrating the importance of appropriate road infrastructure for reducing older driver crashes.M.R.J. Baldock and A.J. McLea

Near-Infrared Observations of the Environments of Radio Quiet QSOs at z >~ 1

We present the results of an infrared survey of QSO fields at z=0.95, 0.995 and 1.5. Each z<1 field was imaged to typical continuum limits of J=20.5, Kprime=19 (5 sigma), and line fluxes of 1.3E10{-16}ergs/cm^2/s (1 sigma)in a 1% interference filter. 16 fields were chosen with z~0.95 targets, 14 with z~0.995 and 6 with z~1.5. A total area of 0.05 square degrees was surveyed, and two emission-line objects were found. We present the infrared and optical photometry of these objects. Optical spectroscopy has confirmed the redshift of one object (at z=0.989) and is consistent with the other object having a similar redshift. We discuss the density of such objects across a range of redshifts from this survey and others in the literature. We also present number-magnitude counts for galaxies in the fields of radio quiet QSOs, supporting the interpretation that they exist in lower density environments than their radio loud counterparts. The J-band number counts are among the first to be published in the J=16--20.Comment: 34 pages, including 12 figures; accepted for publication in the Ap

A novel amniote model of epimorphic regeneration: the leopard gecko, Eublepharis macularius

<p>Abstract</p> <p>Background</p> <p>Epimorphic regeneration results in the restoration of lost tissues and structures from an aggregation of proliferating cells known as a blastema. Among amniotes the most striking example of epimorphic regeneration comes from tail regenerating lizards. Although tail regeneration is often studied in the context of ecological costs and benefits, details of the sequence of tissue-level events are lacking. Here we investigate the anatomical and histological events that characterize tail regeneration in the leopard gecko, <it>Eublepharis macularius</it>.</p> <p>Results</p> <p>Tail structure and tissue composition were examined at multiple days following tail loss, revealing a conserved pattern of regeneration. Removal of the tail results in a consistent series of morphological and histological events. Tail loss is followed by a latent period of wound healing with no visible signs of regenerative outgrowth. During this latent period basal cells of the epidermis proliferate and gradually cover the wound. An additional aggregation of proliferating cells accumulates adjacent to the distal tip of the severed spinal cord marking the first appearance of the blastema. Continued growth of the blastema is matched by the initiation of angiogenesis, followed by the re-development of peripheral axons and the ependymal tube of the spinal cord. Skeletal tissue differentiation, corresponding with the expression of Sox9, and muscle re-development are delayed until tail outgrowth is well underway.</p> <p>Conclusions</p> <p>We demonstrate that tail regeneration in lizards involves a highly conserved sequence of events permitting the establishment of a staging table. We show that tail loss is followed by a latent period of scar-free healing of the wound site, and that regeneration is blastema-mediated. We conclude that the major events of epimorphic regeneration are highly conserved across vertebrates and that a comparative approach is an invaluable biomedical tool for ongoing regenerative research.</p