The Yerkes observatory of the University of Chicago

Mode of access: Internet.

Publications of the Yerkes observatory of the University of Chicago.

On t.p. of v. 2: also issued as v. 8 of the first series of the Decennial publications of the University.

Towards an acoustic environmental observatory

The need for large scale environmental monitoring to manage environmental change is well established. Ecologists have long used acoustics as a means of monitoring the environment in their field work, and so the value of an acoustic environmental observatory is evident. However, the volume of data generated by such an observatory would quickly overwhelm even the most fervent scientist using traditional methods. In this paper we present our steps towards realising a complete acoustic environmental observatory - i.e. a cohesive set of hardware sensors, management utilities, and analytical tools required for large scale environmental monitoring. Concrete examples of these elements, which are in active use by ecological scientists, are also presented

Blast atlas: a virtual observatory for genomes

Following the completion of the draft Human Genome in 2001, genomic sequence data is becoming available at an accelerating rate, fueled by advances in sequencing and computational technology. Meanwhile, large collections of astronomical and geospatial data have allowed the creation of virtual observatories, accessible throughout the world and requiring only commodity hardware. Through a combination of advances in data management, data mining and visualization, this infrastructure enables the development of new scientific and educational applications as diverse as galaxy classification and real-time tracking of earthquakes and volcanic plumes. In the present paper, we describe steps taken along a similar path towards a virtual observatory for genomes – an immersive three-dimensional visual navigation and query system for comparative genomic data.

Dynamic responses of the benthic bacterial community at the Western English Channel observatory site L4 are driven by deposition of fresh phytodetritus

The impact of the seasonal deposition of phytoplankton and phytodetritus on surface sediment bacterial abundance and community composition was investigated at the Western English Channel site L4. Sediment and water samples were collected from January to September in 2012, increasing in frequency during periods of high water column phytoplankton abundance. Compared to the past two decades, the spring bloom in 2012 was both unusually long in duration and contained higher than average biomass. Within spring months, the phytoplankton bloom was well mixed through the water column and showed accumulations near the sea bed, as evidenced by flow cytometry measurements of nanoeukaryotes, water column chlorophyll a and the appearance of pelagic phytoplankton at the sediment. Measurements of chlorophyll and chlorophyll degradation products indicated phytoplankton material was heavily degraded after it reached the sediment surface: the nature of the chlorophyll degradation products (predominantly pheophorbide, pyropheophorbide and hydroxychlorophyllone) was indicative of grazing activity. The abundance of bacterial 16S rRNA genes g−1 sediment (used as a proxy for bacterial biomass) increased markedly with the onset of the phytoplankton bloom, and correlated with measurements of chlorophyll at the surface sediment. Together, this suggests that bacteria may have responded to nutrients released via grazing activity. In depth sequencing of the 16S rRNA genes indicated that the composition of the bacterial community shifted rapidly through-out the prolonged spring bloom period. This was primarily due to an increase in the relative sequence abundance of Flavobacteria.

The role of advection in the distribution of plankton populations at a moored 1-D coastal observatory

The degree to which advection modulates the distribution of plankton populations at a 1-D coastal observatory was assessed at station L4 in the western English Channel (50°15′N 4°13′W, depth 50 m), part of the Western Channel Observatory (WCO). Five tidal-cycle surveys were conducted, three in spring and two in summer 2010. Observations of the physical characteristics of L4 were obtained by using a moored acoustic doppler current profiler (ADCP) and a free-falling microstructure sensor (MSS). The moored ADCP highlighted the presence of vertical shear, with typical values of U during spring tides of ∼0.5 m s−1 at the surface and ∼0.2 m s−1 at the bed. The distribution of phyto- and zooplankton populations above a size threshold of 200 μm were examined using an in-line holographic imaging system, the Holocam. Variability in time as well as depth is a common feature throughout each of the surveys, with examples of recorded numbers of phytoplankton that ranged between 1300 L−1 and 2300 L−1 at the same depth but at different points within the tidal cycle. Further, at the same points in the tidal cycle the number of recorded zooplankton was also seen to vary, specifically with the identification of gelatinous planula in spring that increased the observed number to maximums of between 140 L−1 and 220 L−1 in the upper layer, considerably higher that the corresponding WP-2 net counts for a similar period. Specific aspects of the movement and transfer of plankton relating to advection and interaction with the pycnocline are identified, both across tidal cycles and seasons.

Early-type stars observed in the ESO UVES Paranal Observatory Project - I. Interstellar NaIUV, TiII and CaIIKobservations

We present an analysis of interstellar NaI (lambda(air) = 3302.37 and 3302.98 angstrom), TiII (lambda(air) = 3383.76 angstrom) and CaII K (lambda(air) = 3933.66 angstrom) absorption features for 74 sightlines towards O- and B-type stars in the Galactic disc. The data were obtained from the Ultraviolet and Visual Echelle Spectrograph Paranal Observatory Project, at a spectral resolution of 3.75 km s(-1) and with mean signal-to-noise ratios per pixel of 260, 300 and 430 for the NaI, TiII and CaII observations, respectively. Interstellar features were detected in all but one of the TiII sightlines and all of the CaII sightlines. The dependence of the column density of these three species with distance, height relative to the Galactic plane, HI column density, reddening and depletion relative to the solar abundance has been investigated. We also examine the accuracy of using the NaI column density as an indicator of that for HI. In general, we find similar strong correlations for both Ti and Ca, and weaker correlations for Na. Our results confirm the general belief that Ti and Ca occur in the same regions of the interstellar medium ( ISM) and also that the TiII/CaII ratio is constant over all parameters. We hence conclude that the absorption properties of Ti and Ca are essentially constant under the general ISM conditions of the Galactic disc.