Oxygen transport across the benthic boundary layer: from a 1-D to a 3-D view

The sediment-water interface is a fascinating environment.Bordering the dynamic processes between hydrosphere andgeosphere, it is the gate-keeper for the benthic-pelagiccoupling of carbon and nutrient cycles in aquatic ecosystems.In this region boundary layer hydrodynamics interact withtransport processes across the interface, organic matterdeposited on the sediment surface supports and focuses thebiological activity to a thin veneer teeming with life, and steepchemical gradients provide diverse zones for biological andgeochemical processes.Just as the earth surface appears flat when viewed fromorbit, the sediment surface appears flat when we read mostbiogeochemical literature which describes it with only avertical axis. However, many aspects of sediment biology andgeochemistry require a three-dimensional view to understandtheir essential properties. We need novel approaches withgreater information capacity to study the spatial structures ofbiota, environments, and processes. To stimulate thedevelopment of such approaches, this short review will discuss some of the small-scale characteristics of the benthic boundarylayer, and illustrates the 3-D world of the sea floor based onrecent progress in analytical and experimental techniques. Thefew examples used are taken mostly from the work of our owngroup since brevity forces us to neglect the excellent work ofmany colleagues

Arcsecond resolution images of the chemical structure of the low-mass protostar IRAS 16293-2422

It remains a key challenge to establish the molecular content of different components of low-mass protostars, like their envelopes and disks, and how this depends on the evolutionary stage and/or environment of the young stars. Observations at submillimeter wavelengths provide a direct possibility to study the chemical composition of low-mass protostars through transitions probing temperatures up to a few hundred K in the gas surrounding these sources. This paper presents a large molecular line survey of the deeply embedded protostellar binary IRAS 16293-2422 from the Submillimeter Array (SMA) - including images of individual lines down to approximately 1.5-3" (190-380 AU) resolution. More than 500 individual transitions are identified related to 54 molecular species (including isotopologues) probing temperatures up to about 550 K. Strong chemical differences are found between the two components in the protostellar system with a separation between, in particular, the sulfur- and nitrogen-bearing species and oxygen-bearing complex organics. The action of protostellar outflow on the ambient envelope material is seen in images of CO and SiO and appear to influence a number of other species, including (deuterated) water, HDO. The effects of cold gas-phase chemistry is directly imaged through maps of CO, N2D+ and DCO+, showing enhancements of first DCO+ and subsequently N2D+ in the outer envelope where CO freezes-out on dust grains.Comment: Accepted for publication in A&A, 30 pages, 22 figure

The Evolution of Cluster Early-Type Galaxies over the Past 8 Gyr

We present the Fundamental Plane (FP) of early-type galaxies in the clusters of galaxies RXJ1415.1+3612 at z=1.013. This is the first detailed FP investigation of cluster early-type galaxies at redshift z=1. The distant cluster galaxies follow a steeper FP relation compared to the local FP. The change in the slope of the FP can be interpreted as a mass-dependent evolution. To analyse in more detail the galaxy population in high redshift galaxy clusters at 0.8<z<1, we combine our sample with a previous detailed spectroscopic study of 38 early-type galaxies in two distant galaxy clusters, RXJ0152.7-1357 at z=0.83 and RXJ1226.9+3332 at z=0.89. For all clusters Gemini/GMOS spectroscopy with high signal-to-noise and intermediate-resolution has been acquired to measure the internal kinematics and stellar populations of the galaxies. From HST/ACS imaging, surface brightness profiles, morphologies and structural parameters were derived for the galaxy sample. The least massive galaxies (M=2x10^{10}M_{\sun}) in our sample have experienced their most recent major star formation burst at z_{form}~1.1. For massive galaxies (M>2x10^{11}M_{\sun}) the bulk of their stellar populations have been formed earlier z_{form}>~1.6. Our results confirm previous findings by Jorgensen et al. This suggests that the less massive galaxies in the distant clusters have much younger stellar populations than their more massive counterparts. One explanation is that low-mass cluster galaxies have experienced more extended star formation histories with more frequent bursts of star formation with shorter duration compared to the formation history of high-mass cluster galaxies.Comment: 6 pages, 2 figures, Talk for "Matter Cycles of Galaxies in Clusters", presented at JENAM 2008, Vienna, to be published in Astronomische Nachrichten in Nov 2009 (proceedings of Symposium 6 of the JENAM 2008, Vienna

Compactly generated homotopy categories

Over an associative ring we consider a class $\mathbb{X}$ of left modules which is closed under set-indexed coproducts and direct summands. We investigate when the triangulated homotopy category $\mathsf{K}(\mathbb{X})$ is compactly generated, and give a number of examples.Comment: 20 page

A systematic review of software development cost estimation studies

This paper aims to provide a basis for the improvement of software estimation research through a systematic review of previous work. The review identifies 304 software cost estimation papers in 76 journals and classifies the papers according to research topic, estimation approach, research approach, study context and data set. A web-based library of these cost estimation papers is provided to ease the identification of relevant estimation research results. The review results combined with other knowledge provide support for recommendations for future software cost estimation research, including: 1) Increase the breadth of the search for relevant studies, 2) Search manually for relevant papers within a carefully selected set of journals when completeness is essential, 3) Conduct more studies on estimation methods commonly used by the software industry, and, 4) Increase the awareness of how properties of the data sets impact the results when evaluating estimation methods

Nutrient composition and bioavailability of protein and energy in common fruits and vegetables prepared for human consumption

Growing rats were used as animal model to evaluate the digestibility of energy and protein digestible corrected amino acid score (PDCAAS) in some common fruits and vegetable grown during two subsequent growth seasons in different cultivation systems. The ingredients were cultivated by each of three different farming strategies: LIminusP: low input of feritlizer without pesticides, LIplusP: lowinput of fertilicer and high input of pesticides and LHplusP: high input of fertilizer and high input of pesticides. The protein quality of the dietary ingredients gave rise to the following ranking: apples, carrots, potatoes, kale and peas. The amino acid pattern in peas and potatoes complemented each other fairly well as dietary sources, while lysine turned out to be the limiting amino acid in both carrot and kale. Years, but not cultivation system influenced the protein and amino acid content of the foods