Strong irradiation of protostellar cores in Corona Australis

The importance of the physical environment in the evolution of newly formed low-mass stars remains an open question. In particular, radiation from nearby more massive stars may affect both the physical and chemical structure of these kinds of young stars. Aims: To constrain the physical characteristics of a group of embedded low-mass protostars in Corona Australis in the vicinity of the young luminous Herbig Be star R CrA. Methods: Millimetre wavelength maps of molecular line and continuum emission towards the low-mass star forming region IRS7 near R CrA from the SMA and APEX are presented. The maps show the distribution of 18 lines from 7 species (H2CO, CH3OH, HC3N, c-C3H2, HCN, CN and SiO) on scales from 3" to 60" (400-8000 AU). Using a set of H2CO lines, we estimate the temperatures and column densities in the region using LTE and non-LTE methods. The results are compared with 1-D radiative transfer modelling of the protostellar cores. These models constrain which properties of the central source, envelope, and environment can give rise to the observed line and continuum emission. Results: Most of the H2CO emission from the regions emerges from two elongated narrow ridges dominating the emission picked up in both interferometric and single-dish measurements. The temperatures inferred from the H2CO lines are no less than ~30 K and more likely 50-60 K, and the line emission peaks are offset by ~2500 AU from the location of the embedded protostars. The temperatures can not be explained by the heating from the young stellar objects themselves. Irradiation by the nearby Herbig Be star R CrA could, however, explain the high temperatures. The elevated temperatures can in turn impact the physical and chemical characteristics of protostars and lead to enhanced abundances of typical tracers of photon dominated regions seen in single-dish line surveys of embedded protostars in the region.Comment: Accepted for publication in A&A; 21 pages, 28 figures; Added footnote in Section 2.

Nitrate leaching and spring wheat bread making quality following cultivation of grasslands of different composition, age and management

The influence of sward botanical composition and ley age on grassland residual effects, quality of spring wheat and subsequent nitrate leaching was investigated. Grazed grasslands of different age (1, 2 and 8 production years) and composition (unfertilised grass-clover and fertilised perennial ryegrass) were ploughed and followed by spring wheat and spring barley. For reference, an adjacent field without grassland history but with the same crop sequence in 2002-2003 was treated with increasing quantities of N fertiliser. Yields and N uptake of spring wheat following grasslands always exceeded those of the reference plots with a history of cereal production. The nitrogen fertiliser replacement values of grass-clover and ryegrass were 59-100 and 72-121 kg ha-1, respectively, with the highest values representing the 8-year-old leys. Grain yield and N uptake increased while those for straw decreased with increasing ley age. There were no effects of previous grassland type (grass-clover/ryegrass) on content of protein, starch and gluten, but grassland age significantly influenced protein (P<0.05) and gluten (P<0.01) contents. It is suggested that N mineralisation following the ploughing of older grass leys occurred later than when following the 1st year ley. The protein and gluten contents of wheat following unfertilised grass-clover corresponded to those following cereals given 125-150 kg N ha-1, but the rheological properties of the gluten were different to what could be achieved using equivalent quantities of mineral fertiliser. Probably, the slow release of N from decomposition of old grassland gave a better synchrony between N release and plant demand. Nitrate leaching in year 1 after ploughing was significantly influenced by type of grassland (P<0.001) with 10 and 29 kg N ha-1 leached from grass-clover and ryegrass, respectively. Nitrate leaching following ploughing of 1-year-old leys averaged 11 kg N ha-1 which was significantly lower than the 24 kg N ha-1 following 2 or 8-year-old leys. The flow-weighted mean nitrate concentration decreased from 8.5 mg N l-1 in year 1 after grassland cultivation to 4.5 mg N l-1 in year 2. More N was released following ploughing of ryegrass swards and from grasslands of increasing age, but differences were moderate compared to the estimated N-surplus. This indicates that when organic matter in grasslands is partially decomposed and readily mineralisable N used, the remaining organic N is released only very slowly

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

Ecology of Thioploca spp.: Nitrate and sulfur storage in relation to chemical microgradients and influence of Thioploca spp. on the sedimentary nitrogen cycle

Microsensors, including a recently developed NO3 − biosensor, were applied to measure O2 and NO3 − profiles in marine sediments from the upwelling area off central Chile and to investigate the influence of Thioploca spp. on the sedimentary nitrogen metabolism. The studies were performed in undisturbed sediment cores incubated in a small laboratory flume to simulate the environmental conditions of low O2, high NO3 −, and bottom water current. On addition of NO3 −and NO2 −, Thioploca spp. exhibited positive chemotaxis and stretched out of the sediment into the flume water. In a core densely populated with Thioploca, the penetration depth of NO3 − was only 0.5 mm and a sharp maximum of NO3 − uptake was observed 0.5 mm above the sediment surface. In sediments with only fewThioploca spp., NO3 − was detectable down to a depth of 2 mm and the maximum consumption rates were observed within the sediment. No chemotaxis toward nitrous oxide (N2O) was observed, which is consistent with the observation that Thioploca does not denitrify but reduces intracellular NO3 − to NH4 +. Measurements of the intracellular NO3 − and S0 pools inThioploca filaments from various depths in the sediment gave insights into possible differences in the migration behavior between the different species. Living filaments containing significant amounts of intracellular NO3 − were found to a depth of at least 13 cm, providing final proof for the vertical shuttling of Thioploca spp. and nitrate transport into the sediment

A Pulse Shaping Algorithm of a Coherent Matter Wave. Controlling Reaction Dynamics

A pulse shaping algorithm for a matter wave with the purpose of controlling a binary reaction has been designed. The scheme is illustrated for an Eley-Rideal reaction where an impinging matter-wave atom recombines with an adsorbed atom on a metal surface. The wave function of the impinging atom is shaped such that the desorbing molecule leaves the surface in a specific vibrational state.Comment: 4 pages, 5 figure

Self-Similarity and Lamperti Convergence for Families of Stochastic Processes

We define a new type of self-similarity for one-parameter families of stochastic processes, which applies to a number of important families of processes that are not self-similar in the conventional sense. This includes a new class of fractional Hougaard motions defined as moving averages of Hougaard L\'evy process, as well as some well-known families of Hougaard L\'evy processes such as the Poisson processes, Brownian motions with drift, and the inverse Gaussian processes. Such families have many properties in common with ordinary self-similar processes, including the form of their covariance functions, and the fact that they appear as limits in a Lamperti-type limit theorem for families of stochastic processes.Comment: 23 pages. IMADA preprint 2010-09-0

OVERLEVELSE AF INDIKATORORGANISMER OG SMITSTOFFER I KOMPOSTTOILETTER OG VED SIMULERET CENTRALISERET EFTERKOMPOSTERING AF AFFØRING FRA MENNESKER

Som resultat af projekterne kan drages følgende hovedkonklusioner om kompostering af fæces fra mennesker: Fæces fra de undersøgte typer af kompostbeholdere bør ikke anvendes til jordbrugsformål uden viderebehandling, da dette skønnes at være behæftet med hygiejne- og sundhedsrisici. Det skyldes, at der ikke blev dokumenteret egentlige termofile temperaturstigninger i fæcesmaterialet i komposttoiletenhederne i Hjortshøj, Dyssekilde og Sverige, og at fækale indikatorbakteriers antal varierede voldsomt, og der ingen entydig tendens var til forekomst af lavere kimtal ved lange opbevaringstider af de opsamlede fækalier

Screening of organically based fungicides for apple scab (Venturia inaequalis) control and a histopathological study of the mode of action of a resistance inducer.

A range of possible substitutes for copper-based fungicides for control of apple scab (Venturia inaequalis) in organic growing were tested in laboratory and growth chamber experiments in the Danish project StopScab (2002-2004). Eighteen crude plant extracts, 19 commercial plant-based products and 6 miscellaneous compounds were tested for their ability to reduce scab symptoms on apple seedlings. Most of the compounds were also tested for their effect on conidium germination on glass slides. Fourteen of the crude plant extracts, 13 of the commercial plant products and 5 of the miscellaneous compounds showed promising control efficacies when used either preventively or curatively in the plant assay. A histopathological study was carried out on the mode of action of the resistance inducer, acibenzolar-S-methyl (ASM), which reduced scab severity and sporulation on apple seedlings in several plant assays when applied as preventive treatment. The effect of the inducer on key pre- and post-penetration events of V. inaequalis was studied and compared to these events in water-treated control leaves. The histopathological study showed that the inducer had its strongest effect on post-penetration events indicated by delayed infection and reduced stroma development. In addition, a small but significant inhibition of conidial germination and a stimulation of germ tube length were observed. This investigation provides new histopathological evidence for the mode of action of ASM against V. inaequalis and serves as a model for evaluation of the mechanisms by which the organically based fungicides reduce infection of V. inaequalis