We present new evidence for mature stellar populations with ages >100 Myr in massive galaxies (M stellar > 10 10 M ) seen at a time when the Universe was less than 1 Gyr old. We analyse the prominent detections of two z ≈ 6 star-forming galaxies (SBM03#1 and #3) made at wavelengths corresponding to the rest-frame optical using the Infrared Array Camera camera onboard the Spitzer Space Telescope. We had previously identified these galaxies in Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) / Great Observatories Origins Deep Survey (GOODS) images of Chandra Deep Field South through the 'idrop' Lyman-break technique, and subsequently confirmed the identification spectroscopically with the Keck telescope. The new Spitzer photometry reveals significant Balmer/ 4000-Å discontinuities, indicative of dominant stellar populations with ages >100 Myr. Fitting a range of population synthesis models (for normal initial mass functions) to the HST/Spitzer photometry yields ages of 250-650 Myr and implied formation redshifts z f ≈ 7.5-13.5 in presently-accepted world models. Remarkably, our sources have best-fitting stellar masses of 1.3-3.8 × 10 10 M (95 per cent confidence) assuming a Salpeter IMF. This indicates that at least some galaxies with stellar masses >20 per cent of those of a present-day L * galaxy had already assembled within the first Gyr after the Big Bang. We also deduce that the past average star formation rate must be comparable to the current observed rate (SFR UV ∼ 5-30 M yr −1 ), suggesting that there may have been more vigorous episodes of star formation in such systems at higher redshifts. Although a small sample, limited primarily by Spitzer's detection efficiency, our result lends support to the hypothesis advocated in our earlier analyses of the Ultra Deep Field and GOODS HST/ACS data. The presence of established systems at z ≈ 6 suggests that long-lived sources at earlier epochs (z > 7) played a key role in reionizing the Universe.

Aims. We study the kinematics and dynamics of the extreme outer halo of M 87, the central galaxy in the Virgo cluster, and its transition to the intracluster light (ICL). Methods. We present high resolution FLAMES/VLT spectroscopy of intracluster planetary nebula (PN) candidates, targeting three new fields in the Virgo cluster core with surface brightness down to μ B = 28.5. Based on the projected phase space information (sky positions and line-of-sight velocities) we separate galaxy and cluster components in the confirmed PN sample. We then use the spherical Jeans equation and the total gravitational potential as traced by the X-ray emission to derive the orbital distribution in the outer stellar halo of M 87. We determine the luminosity-specific PN number for the M 87 halo and the ICL from the photometric PN catalogs and sampled luminosities, and discuss the origin of the ICL in Virgo based on its measured PN velocities. Results. We confirm a further 12 PNs in Virgo, five of which are bound to the halo of M 87, and the remainder are true intracluster planetary nebulas (ICPNs). The M 87 PNs are confined to the extended stellar envelope of M 87, within a projected radius of ∼160 kpc, while the ICPNs are scattered across the whole surveyed region between M 87 and M 86, supporting a truncation of M 87's luminous outer halo at a 2σ level. The line-of-sight velocity distribution of the M 87 PNs at projected radii of 60 kpc and 144 kpc shows (i) no evidence for rotation of the halo along the photometric major axis; and (ii) that the velocity dispersion decreases in the outer halo, down to σ last = 78 ± 25 km s −1 at 144 kpc. The Jeans model for the M 87 halo stars fits the observed line-of-sight velocity dispersion profile only if the stellar orbits are strongly radially anisotropic (β 0.4 at r 10 kpc increasing to 0.8 at the outer edge), and if additionally the stellar halo is truncated at 150 kpc average elliptical radius. The α-parameters for the M 87 halo and the ICL are in the range of values observed for old (>10 Gyr) stellar populations. Conclusions. Both the spatial segregation of the PNs at the systemic velocity of M 87 and the dynamical model support that the stellar halo of M 87 ends at ∼150 kpc. We discuss several possible explanations for the origin of this truncation but are unable to discriminate between them: tidal truncation following an earlier encounter of M 87 with another mass concentration in the Virgo core, possibly around M 84, early AGN feedback effects, and adiabatic contraction due to the cluster dark matter collapsing onto M 87. From the spatial and velocity distribution of the ICPNs we infer that M 87 and M 86 are falling towards each other and that we may be observing them just before the first close pass. The new PN data support the view that the core of the Virgo cluster is not yet virialized but is in an ongoing state of assembly, and that massive elliptical galaxies are important contributors to the ICL in the Virgo cluster.

We present a spectroscopic campaign to follow-up red colour-selected candidate massive galaxies in two high redshift proto-clusters surrounding radio galaxies. We observed a total of 57 galaxies in the field of MRC 0943−242 (z = 2.93) and 33 in the field of MRC 1138−262 (z = 2.16) with a mix of optical and near-infrared multi-object spectroscopy. We confirm two red galaxies in the field of MRC 1138−262 at the redshift of the radio galaxy. Based on an analysis of their spectral energy distributions, and their derived star formation rates from the Hα and observed frame 24 μm flux, one object belongs to the class of dust-obscured star-forming red galaxies, while the other is evolved with little ongoing star formation. This result represents the first red and mainly passively evolving galaxy to be confirmed as companion galaxies in a z > 2 proto-cluster. Both red galaxies in MRC 1138−262 are massive, of the order of 4−6 × 10 11 M . They lie along a colour−magnitude relation which implies that they formed the bulk of their stellar population around z = 4. In the MRC 0943−242 field we find no red galaxies at the redshift of the radio galaxy but we do confirm the effectiveness of our JHK s selection of galaxies at 2.3 < z < 3.1, finding that 10 out of 18 (56%) of JHK s -selected galaxies whose redshifts could be measured fall within this redshift range. We also serendipitously identify an interesting foreground structure of 6 galaxies at z = 2.6 in the field of MRC 0943−242. This may be a proto-cluster itself, but complicates any interpretation of the red sequence build-up in MRC 0943−242 until more redshifts can be measured.

We present deep Keck spectroscopy, using the Deep Imaging Multi‐Object Spectrograph and the Low‐Resolution Imaging Spectrometer spectrographs, of a large and representative sample of 67 extremely red objects (EROs) to H= 20.5 in three fields (SSA22, Chandra Deep Field South and NTT Deep Field) drawn from the Las Campanas Infrared Survey (LCIRS). Using the colour cut (I−H) > 3.0 (Vega magnitudes) adopted in earlier papers in this series, we verify the efficiency of this selection for locating and studying distant old sources. Spectroscopic redshifts are determined for 44 sources, of which only two are contaminating low‐mass stars. When allowance is made for incompleteness, the spectroscopic redshift distribution closely matches that predicted earlier on the basis of photometric data. Our spectra are of sufficient quality that we can address the important question of the nature and homogeneity of the z > 0.8 ERO population. A dominant old stellar population is inferred for 75 per cent of our spectroscopic sample, a higher fraction than that seen in smaller, less complete samples with broader photometric selection criteria (e.g. R−K). However, only 28 per cent have spectra with no evidence of recent star formation activity, such as would be expected for a strictly passively evolving population. More than ∼30 per cent of our absorption‐line spectra are of the ‘E+A’ type with prominent Balmer absorption consistent, on average, with mass growth of 5–15 per cent in the past gigayear. We use our spectroscopic redshifts to improve earlier estimates of the spatial clustering of this population as well as to understand the significant field‐to‐field variation. Our spectroscopy enables us to pinpoint a filamentary structure at z= 1.22 in the Chandra Deep Field South. Overall, our study suggests that the bulk of the ERO population is an established population of clustered massive galaxies undergoing intermittent activity consistent with continued growth over the redshift interval 0.8 < z < 1.6.

Minimally invasive delivery of "living cell factories" consisting of cells and therapeutic agents has gained wide attention for next generation biomaterial device systems for multiple applications including musculoskeletal tissue regeneration, diabetes and cancer. Cellularbased microcapsules and microcarrier systems offer several attractive features for this particular purpose. One such technology capable of generating these types of systems is electrohydrodynamic (EHD) spraying. Depending on various parameters including applied voltage, biomaterial properties (viscosity, conductivity) and needle geometry, complex structures and arrangements can be fabricated for therapeutic strategies. In this paper, we outline the advances in the use of EHD technology specifically in the manipulation of bioactive and dynamic material systems to control size, composition and configuration in the development of minimally invasive micro-scaled biopolymeric systems. The exciting therapeutic applications of this technology, future perspectives and associated challenges are also presented.