A high abundance of massive galaxies 3-6 billion years after the Big Bang.

Hierarchical galaxy formation is the model whereby massive galaxies form from an assembly of smaller units. The most massive objects therefore form last. The model succeeds in describing the clustering of galaxies, but the evolutionary history of massive galaxies, as revealed by their visible stars and gas, is not accurately predicted. Near-infrared observations (which allow us to measure the stellar masses of high-redshift galaxies) and deep multi-colour images indicate that a large fraction of the stars in massive galaxies form in the first 5 Gyr (refs 4-7), but uncertainties remain owing to the lack of spectra to confirm the redshifts (which are estimated from the colours) and the role of obscuration by dust. Here we report the results of a spectroscopic redshift survey that probes the most massive and quiescent galaxies back to an era only 3 Gyr after the Big Bang. We find that at least two-thirds of massive galaxies have appeared since this era, but also that a significant fraction of them are already in place in the early Universe.

Endoscopic anatomy of the orbital floor and maxillary sinus.

Endoscopic repair of orbital blow-out fractures could become a predictable and efficient treatment alternative to traditional methods. However, maxillary sinus endoscopy provides a complex and disorienting view of the orbital floor. To be a useful and consistent technique for providing access to the orbital floor, specific knowledge of maxillary endoscopic anatomy is required. The purpose of the study was to provide an anatomic description of the orbital floor via the endoscopic approach. Objectives include defining consistent landmarks for use in endoscopic repair of orbital floor fractures. Using 0- and 30-degree rigid endoscopes, 6 fresh cadavers (12 maxillary sinuses) were examined via a standard Caldwell-Luc approach. Computed tomographic scans, plastic molds, and digital images were used to compare observable averages within bony anatomy. Potential bony landmarks were correlated with soft-tissue anatomy in fresh specimens. The maxillary ostium, orbital floor, and lateral ethmoid air cells were visualized, and their structures were described. Observations were made in relation to the anatomy of the orbital floor and maxillary sinus, including fracture pattern and force transmission pathways. An "orbitomaxillary" sinus bony thickening was identified and described for the first time. This study provides the basis for further refinement of surgical technique and opens the door for future clinical trials using endoscopic repair.