School-age spirometry in survivors of chronic lung disease of prematurity in the surfactant era

Objective: To assess whether school-age spirometry and lung volume outcomes of preterm infants with history of moderate to severe respiratory distress syndrome (RDS), born in the surfactant era and treated with conventional mechanical ventilation (IMV) and discharged home with or without the diagnosis of BPD (hronic lung disease of prematurity), differ from those of term neonates (controls). Participants: The study included 148 Caucasian school-aged children (38 preterm infants without BPD, 20 preterm infants with BPD and 90 term infants). All infants were born at the Department of Pathology of Pregnancy and Labor, Pomeranian Medical University, Szczecin, Poland. Methods: Respiratory outcome in school-aged children was assessed using spirometry with the evaluation of flow and volume parameters, adjusted for age, weight and gender. The differences in spirometry were tested by the Wilcoxon or Mann-Whitney tests. Linear correlation and regression were also used. Results: No statistically significant differences between the spirometric parameters in preterm infants with and without BPD were found. All investigated parameters were significantly lower in both ventilated groups compared to term controls, with the exception of ERV%, which was significantly higher. Conclusions: The necessity to use assisted ventilation in preterm infants without neurological disorders most probably had an adverse effect on the lung function, assessed by spirometry at the age of 9-10 years, in the groups of children discharged home with or without BPD. Regardless of BPD, lung function parameters in prematurely born children with respiratory distress syndrome are always worse than in term controls

High angular resolution integral-field spectroscopy of the Galaxy's nuclear cluster: a missing stellar cusp?

We report on the structure of the nuclear star cluster in the innermost 0.16 pc of the Galaxy as measured by the number density profile of late-type giants. Using laser guide star adaptive optics in conjunction with the integral field spectrograph, OSIRIS, at the Keck II telescope, we are able to differentiate between the older, late-type ($\sim$ 1 Gyr) stars, which are presumed to be dynamically relaxed, and the unrelaxed young ($\sim$ 6 Myr) population. This distinction is crucial for testing models of stellar cusp formation in the vicinity of a black hole, as the models assume that the cusp stars are in dynamical equilibrium in the black hole potential. Based on the late-type stars alone, the surface stellar number density profile, $\Sigma(R) \propto R^{-\Gamma}$, is flat, with $\Gamma = -0.27\pm0.19$. Monte Carlo simulations of the possible de-projected volume density profile, n(r) $\propto r^{-\gamma}$, show that $\gamma$ is less than 1.0 at the 99.73 % confidence level. These results are consistent with the nuclear star cluster having no cusp, with a core profile that is significantly flatter than predicted by most cusp formation theories, and even allows for the presence of a central hole in the stellar distribution. Of the possible dynamical interactions that can lead to the depletion of the red giants observable in this survey -- stellar collisions, mass segregation from stellar remnants, or a recent merger event -- mass segregation is the only one that can be ruled out as the dominant depletion mechanism. The lack of a stellar cusp around a supermassive black hole would have important implications for black hole growth models and inferences on the presence of a black hole based upon stellar distributions.Comment: 35 pages, 5 tables, 12 figures, accepted by Ap

Epigenetic influences in the development of bronchopulmonary dysplasia

Abstract Lung development is orchestrated by highly integrated morphogenic programs of interrelated patterns of gene and protein expression. Both genetic and epigenetic influences may alter the developing lung in the canalicular and saccular phase of lung development that lead to the development of bronchopulmonary dysplasia (BPD). Maternal exposures to toxins, and especially tobacco smoke associated nicotine nitrosamine ketones, fetal and neonatal infections (with or without chorioamnionitis) and techniques of neonatal ventilator management including surfactant therapy in concert with innate genetic susceptibility have life-long consequences for the infant afflicted with BPD. Exposure to supplemental oxygen poses another threat to the prematurely newborn and increases the risk for BPD and retinopathy of prematurity, but other effects in later life have been note among infants given oxygen as newborns. Thus a greater focus on these epigenetic influences and novel strategies to care for the preterm infant will hopefully reduce the worldwide burden of BPD and increase awareness regarding epigenetic mechanisms that determine long term health and well-being

Natural surfactant substitution in respiratory distress syndrome

Peer Reviewe

The structure of the nuclear stellar cluster of the Milky Way

We present high-resolution seeing limited and AO NIR imaging observations of the stellar cluster within about one parsec of Sgr A*, the massive black hole at the centre of the Milky Way. Stellar number counts and the diffuse background light density were extracted from these observations in order to examine the structure of the nuclear stellar cluster.Our findings are as follows: (a) A broken-power law provides an excellent fit to the overall structure of the GC nuclear cluster. The power-law slope of the cusp is $\Gamma=0.19\pm0.05$, the break radius is $R_{\rm break} = 6.0'' \pm 1.0''$ or $0.22\pm0.04$ pc, and the cluster density decreases with a power-law index of $\Gamma=0.75\pm0.1$ outside of $R_{\rm break}$. (b) Using the best velocity dispersion measurements from the literature, we derive higher mass estimates for the central parsec than assumed until now. The inferred density of the cluster at the break radius is $2.8\pm1.3\times 10^{6} {\rm M_{\odot} pc^{-3}}$. This high density agrees well with the small extent and flat slope of the cusp. Possibly, the mass of the stars makes up only about 50% of the total cluster mass. (c) Possible indications of mass segregation in the cusp are found (d) The cluster appears not entirely homogeneous. Several density clumps are detected that are concentrated at projected distances of $R=3''$ and $R=7''$ from Sgr A*.(e) There appears to exist an under-density of horizontal branch/red clump stars near $R=5''$, or an over-density of stars of similar brightness at $R=3''$ and $R=7''$. (f) The extinction map in combination with cometary-like features in an L'-band image may provide support for the assumption of an outflow from Sgr A*.Comment: accepted for publication by A&A; please contact first author for higher quality figure

Partial suppression of the radial orbit instability in stellar systems

It is well known that the simple criterion proposed originally by Polyachenko and Shukhman (1981) for the onset of the radial orbit instability, although being generally a useful tool, faces significant exceptions both on the side of mildly anisotropic systems (with some that can be proved to be unstable) and on the side of strongly anisotropic models (with some that can be shown to be stable). In this paper we address two issues: Are there processes of collisionless collapse that can lead to equilibria of the exceptional type? What is the intrinsic structural property that is responsible for the sometimes noted exceptional stability behavior? To clarify these issues, we have performed a series of simulations of collisionless collapse that start from homogeneous, highly symmetrized, cold initial conditions and, because of such special conditions, are characterized by very little mixing. For these runs, the end-states can be associated with large values of the global pressure anisotropy parameter up to 2K_r/K_T \approx 2.75. The highly anisotropic equilibrium states thus constructed show no significant traces of radial anisotropy in their central region, with a very sharp transition to a radially anisotropic envelope occurring well inside the half-mass radius (around 0.2 r_M). To check whether the existence of such almost perfectly isotropic "nucleus" might be responsible for the apparent suppression of the radial orbit instability, we could not resort to equilibrium models with the above characteristics and with analytically available distribution function; instead, we studied and confirmed the stability of configurations with those characteristics by initializing N-body approximate equilibria (with given density and pressure anisotropy profiles) with the help of the Jeans equations.Comment: 26 pages, 9 figures, accepted for publication in The Astrophysical Journa

The Milky Way Nuclear Star Cluster

In the center of the Milky Way, as well as in many other galaxies, a compact star cluster around a very massive black hole is observed. One of the possible explanations for the formation of such Nuclear Star Clusters is based on the 'merging' of globular clusters in the inner galactic potential well. By mean of sophisticated N-body simulations, we checked the validity of this hypothesis and found that it may actually has been the one leading to the formation of the Milky Way Nuclear Star Cluster.Comment: 4 pages, 2 figures, proceedings of "Stellar Clusters and Associations - A RIA workshop on GAIA", 23-27 May 2011, Granada, Spai

Kinematics, Abundances, and Origin of Brightest Cluster Galaxies

We present kinematic parameters and absorption line strengths for three brightest cluster galaxies, NGC 6166, NGC 6173 and NGC 6086. We find that NGC 6166 has a velocity dispersion profile which rises beyond 20 arcsec from the nucleus, with a halo velocity dispersion in excess of 400 km/s. All three galaxies show a positive and constant h4 Hermite moment. The rising velocity dispersion profile in NGC 6166 thus indicates an increasing mass-to-light ratio. Rotation is low in all three galaxies, and NGC 6173 and NGC 6086 show possible kinematically decoupled cores. All three galaxies have Mg2 gradients similar to those found in normal bright ellipticals, which are not steep enough to support simple dissipative collapse models, but these could be accompanied by dissipationless mergers which would tend to dilute the abundance gradients. The [Mg/Fe] ratios in NGC 6166 and NGC 6086 are higher than that in NGC 6173, and if NGC 6173 is typical of normal bright ellipticals, this suggests that cDs cannot form from late mergers of normal galaxies.Comment: 21 pages, accepted for publication in MNRA

The nuclear star cluster of the Milky Way

The nuclear star cluster of the Milky Way is a unique target in the Universe. Contrary to extragalactic nuclear star clusters, using current technology it can be resolved into tens of thousands of individual stars. This allows us to study in detail its spatial and velocity structure as well as the different stellar populations that make up the cluster. Moreover, the Milky Way is one of the very few cases where we have firm evidence for the co-existence of a nuclear star cluster with a central supermassive black hole, Sagittarius A*. The number density of stars in the Galactic center nuclear star cluster can be well described, at distances $\gtrsim1$ pc from Sagittarius A*, by a power-law of the form $\rho(r)\propto r^{-\gamma}$ with an index of $\gamma\approx1.8$. In the central parsec the index of the power-law becomes much flatter and decreases to $\gamma\approx1.2$. We present proper motions for more than 6000 stars within 1 pc in projection from the central black hole. The cluster appears isotropic at projected distances $\gtrsim0.5$ pc from Sagittarius A*. Outside of 0.5 pc and out to 1.0 pc the velocity dispersion appears to stay constant. A robust result of our Jeans modeling of the data is the required presence of $0.5-2.0\times10^{6} M_{\odot}$ of extended (stellar) mass in the central parsec of the Galaxy.Comment: To appear in the proceedings of "The Universe under the Microscope - Astrophysics at High Angular Resolution", Journal of Physics:Conference Series (IOP; http://www.iop.org/EJ/conf) This version has been slightly modified (e.g. double-log plot in right hand panel of Figure 5

The Giant Radio Galaxy MRC B0319-454: Circumnuclear Structure of the Host Galaxy ESO248-G10

We present optical and near-infrared images and spectra of ESO248-G10, the host of giant radio galaxy MRC B0319-454. From near-infrared colours, the active nucleus is shown to be reddened by hot dust emission or dust extinction. Star forming regions are identified beyond a radius of 5" (8.1 kpc) where hot gas is prevalent. The optical spectrum shows gas rotation at speeds of up to 350km/s out to >=32kpc along the radio axis. A model is proposed in which the giant elliptical is triaxial with the radio axis along the short axis, and the figure rotation is around the long axis. From the model, the angles of the principal axes are psi=34 degrees, theta=65 degrees, and phi=19 degrees with axis ratios of B/A=0.75 and C/A=0.69. A second velocity feature from 5" to 15" to the north-east of the nucleus is proposed to be a merging gas-rich galaxy inducing star formation while settling into an orbit about the figure rotation axis.Comment: Accepted for publication in The Astrophysical Journal. 22 pages, 12 figure