On the co-evolution of supermassive black holes and their host galaxies since z = 3

[Abridged] To investigate the evolution in the relation between galaxy stellar and central black hole mass we construct a volume limited complete sample of 85 AGN with host galaxy stellar masses M_{*} > 10^{10.5} M_{sol}, and specific X-ray luminosities L_{X} > 2.35 x 10^{43} erg s^{-1} at 0.4 < z < 3. We calculate the Eddington limiting masses of the supermassive black holes residing at the centre of these galaxies, and observe an increase in the average Eddington limiting black hole mass with redshift. By assuming that there is no evolution in the Eddington ratio (\mu) and then that there is maximum possible evolution to the Eddington limit, we quantify the maximum possible evolution in the M_{*} / M_{BH} ratio as lying in the range 700 < M_{*}/M_{BH} < 10000, compared with the local value of M_{*}/M_{BH} ~ 1000. We furthermore find that the fraction of galaxies which are AGN (with L_{X} > 2.35 x 10^{43} erg s^{-1}) rises with redshift from 1.2 +/- 0.2 % at z = 0.7 to 7.4 +/- 2.0 % at z = 2.5. We use our results to calculate the maximum timescales for which our sample of AGN can continue to accrete at their observed rates before surpassing the local galaxy-black hole mass relation. We use these timescales to calculate the total fraction of massive galaxies which will be active (with L_{X} > 2.35 x 10^{43} erg s^{-1}) since z = 3, finding that at least ~ 40% of all massive galaxies will be Seyfert luminosity AGN or brighter during this epoch. Further, we calculate the energy density due to AGN activity in the Universe as 1.0 (+/- 0.3) x 10^{57} erg Mpc^{-3} Gyr^{-1}, potentially providing a significant source of energy for AGN feedback on star formation. We also use this method to compute the evolution in the X-ray luminosity density of AGN with redshift, finding that massive galaxy Seyfert luminosity AGN are the dominant source of X-ray emission in the Universe at z < 3.Comment: 25 pages, 10 figures, accepted for publication in MNRA

Three-dimensional Motion Analysis of Lip and Mandibular Movements during Mastication

Many aspects of the coordination of lip and mandibular movements in the process of eating have not yet been clarified. This time, aiming to objectively evaluate lip and mandibular movements when chewing, the movements of the corners of the mouth and the mandible during mastication were measured three-dimensionally and analyzed. The subjects were 20 healthy women with individual normal occlusion. The test food was a commercially-available biscuit with a weight of 1 g. With six measuring points set for the lips and pogonion, the movements at those measuring points were captured with two CCD cameras during mastication, and the resulting images were analyzed with a three-dimensional motion analysis system. The analysis result showed that X- and Z-axis movements occurred on the working-side corner of the mouth, with Z-axis movements preceding X-axis movements, while on the balancing-side corner of the mouth, X- and Z-axis movements occurred simultaneously. Data on the amount, time taken, and speed of movements measured at each anatomical landmark showed that the working-side corner of the mouth moved a greater distance at a faster pace and, therefore, in less time than that of the balancing-side corner of the mouth. This is conceivably due to the aforementioned differences in X- and Z-axis movements of the working-side and balancing-side corners of the mouth. Further comparisons and studies with expansion of the subjects to include children will be necessary

Mechanotransduction and growth factor signaling in hydrogel-based microenvironments

The extracellular matrix (ECM) is a highly-hydrated mesh of fibrillar proteins a glycosaminoglycans that surrounds cells and provides biophysical and biochemical stimuli. The ECM allows cell adhesion and mechanotransductive cues but it is also a reservoir of growth factors, which are of critical importance in shaping cell phenotypes. Hydrogels have been engineered as materials that can recapitulate the properties of the ECM, by controlling their physical properties and incorporating growth factors. This article provides an overview of the latest findings about the control of cell mechanotransduction and growth factor signaling using hydrogels. Hydrogels can be fabricated with controlled stiffness (i.e., to mimic properties of soft and hard tissues), viscoelasticity (tissues have dynamic properties, e.g., cartilage) or degradability (e.g., triggered by cell secreted proteases). Furthermore, hydrogels can be tuned to present specific ligands and ligand spacing, to control cell adhesion and mechanotransductive signaling cascades. Further, hydrogels can be engineered to present or immobilize growth factors, providing a sustainable release of them. To conclude, some examples are presented here to show the use of hydrogels as tools to exploit the synergistic effect of growth factors and cell mechanosensing to drive (stem) cell differentiation