Assessing the influence of the carbon oxidation-reduction state on organic pollutant biodegradation in algal-bacterial photobioreactors

The influence of the carbon oxidation-reduction state (CORS) of organic pollutants on their biodegradation in enclosed algal-bacterial photobioreactors was evaluated using a consortium of enriched wild-type methanotrophic bacteria and microalgae. Methane, methanol and glucose (with CORS -4, -2 and 0, respectively) were chosen as model organic pollutants. In the absence of external oxygen supply, microalgal photosynthesis was not capable of supporting a significant methane and methanol biodegradation due to their high oxygen demands per carbon unit, while glucose was fully oxidized by photosynthetic oxygenation. When bicarbonate was added, removal efficiencies of 37¿±¿4% (20 days), 65¿±¿4% (11 days) and 100% (2 days) were recorded for CH(4,) CH(3)OH and C(6)H(12)O(6), respectively due to the additional oxygen generated from photosynthetic bicarbonate assimilation. The use of NO(3)(-) instead of NH(4)(+) as nitrogen source (N oxidation-reduction state of +5 vs. -3) resulted in an increase in CH(4) degradation from 0 to 33¿±¿3% in the absence of bicarbonate and from 37¿±¿4% to 100% in the presence of bicarbonate, likely due to a decrease in the stoichiometric oxygen requirements and the higher photosynthetic oxygen production. Hypothetically, the CORS of the substrates might affect the CORS of the microalgal biomass composition (higher lipid content). However, the total lipid content of the algal-bacterial biomass was 19¿±¿7% in the absence and 16¿±¿2% in the presence of bicarbonat

Network dynamics of ongoing social relationships

Many recent large-scale studies of interaction networks have focused on networks of accumulated contacts. In this paper we explore social networks of ongoing relationships with an emphasis on dynamical aspects. We find a distribution of response times (times between consecutive contacts of different direction between two actors) that has a power-law shape over a large range. We also argue that the distribution of relationship duration (the time between the first and last contacts between actors) is exponentially decaying. Methods to reanalyze the data to compensate for the finite sampling time are proposed. We find that the degree distribution for networks of ongoing contacts fits better to a power-law than the degree distribution of the network of accumulated contacts do. We see that the clustering and assortative mixing coefficients are of the same order for networks of ongoing and accumulated contacts, and that the structural fluctuations of the former are rather large.Comment: to appear in Europhys. Let

From the discrete to the continuous - towards a cylindrically consistent dynamics

Discrete models usually represent approximations to continuum physics. Cylindrical consistency provides a framework in which discretizations mirror exactly the continuum limit. Being a standard tool for the kinematics of loop quantum gravity we propose a coarse graining procedure that aims at constructing a cylindrically consistent dynamics in the form of transition amplitudes and Hamilton's principal functions. The coarse graining procedure, which is motivated by tensor network renormalization methods, provides a systematic approximation scheme towards this end. A crucial role in this coarse graining scheme is played by embedding maps that allow the interpretation of discrete boundary data as continuum configurations. These embedding maps should be selected according to the dynamics of the system, as a choice of embedding maps will determine a truncation of the renormalization flow.Comment: 22 page

Effects of invisible particle emission on global inclusive variables at hadron colliders

We examine the effects of invisible particle emission in conjunction with QCD initial state radiation (ISR) on quantities designed to probe the mass scale of new physics at hadron colliders, which involve longitudinal as well as transverse final-state momenta. This is an extension of our previous treatment, arXiv:0903.2013, of the effects of ISR on global inclusive variables. We present resummed results on the visible invariant mass distribution and compare them to parton-level Monte Carlo results for top quark and gluino pair-production at the LHC. There is good agreement as long as the visible pseudorapidity interval is large enough (eta ~ 3). The effect of invisible particle emission is small in the case of top pair production but substantial for gluino pair production. This is due mainly to the larger mass of the intermediate particles in gluino decay (squarks rather than W-bosons). We also show Monte Carlo modelling of the effects of hadronization and the underlying event. The effect of the underlying event is large but may be approximately universal.Comment: 22 pages, expanded sections and other minor modifications. Version published in JHE

(Broken) Gauge Symmetries and Constraints in Regge Calculus

We will examine the issue of diffeomorphism symmetry in simplicial models of (quantum) gravity, in particular for Regge calculus. We find that for a solution with curvature there do not exist exact gauge symmetries on the discrete level. Furthermore we derive a canonical formulation that exactly matches the dynamics and hence symmetries of the covariant picture. In this canonical formulation broken symmetries lead to the replacements of constraints by so--called pseudo constraints. These considerations should be taken into account in attempts to connect spin foam models, based on the Regge action, with canonical loop quantum gravity, which aims at implementing proper constraints. We will argue that the long standing problem of finding a consistent constraint algebra for discretized gravity theories is equivalent to the problem of finding an action with exact diffeomorphism symmetries. Finally we will analyze different limits in which the pseudo constraints might turn into proper constraints. This could be helpful to infer alternative discretization schemes in which the symmetries are not broken.Comment: 32 pages, 15 figure

Cutting out continuations

In the field of program transformation, one often transforms programs into continuation-passing style to make their flow of control explicit, and then immediately removes the resulting continuations using defunctionalisation to make the programs first-order. In this article, we show how these two transformations can be fused together into a single transformation step that cuts out the need to first introduce and then eliminate continuations. Our approach is calculational, uses standard equational reasoning techniques, and is widely applicable

Subduction in the subtropical gyre : Seasoar cruises data report

The overall objective of the Subduction Accelerated Research Initiative (ARI) was to bring together several techniques to address the formation and evolution of newly formed water masses. The Seasoar component provided surveys of temperature and salinity to help determine the spatial varability of the temperature, salinity and density fields in both the active frontal regions and in the vicinity of subducting water tagged by bobbers. Data were collected in the eastern North Atlantic Ocean in spring 1991, winter 1992, winter 1993 and spring 1994. "Star" patterns were used to study the mesoscale varability. Temperature, pressure and thickness for each pattern were objectively mapped on potential density surfaces of 26.5, 26.7 and 26.9 kg/m3. Acoustic Doppler Current Profies (ADCP) maps were also created for the the two shallower density surfaces. We describe the Seasoar data collected during the four cruises. A CD-Rom includes 1- and 3-second conductivity-temperature-depth (CTD), cruise navigation, ADCP and Seasoar engineering data, as well as color figures of these data. This data report can also be viewed using an internet information browser (i.e., Mosaic, Netscape) using the provided CD-Rom.Funding was provided by the Office of Naval Research through Grants Nos, N00014-91-J-1585, N00014-90-J-1425. and N00014-90-J-1508

Regge calculus from a new angle

In Regge calculus space time is usually approximated by a triangulation with flat simplices. We present a formulation using simplices with constant sectional curvature adjusted to the presence of a cosmological constant. As we will show such a formulation allows to replace the length variables by 3d or 4d dihedral angles as basic variables. Moreover we will introduce a first order formulation, which in contrast to using flat simplices, does not require any constraints. These considerations could be useful for the construction of quantum gravity models with a cosmological constant.Comment: 8 page

Higher levels of CO2 during late incubation alter the hatch time of chicken embryos

status: publishe