Organic loading rate: a promising microbial management tool in anaerobic digestion

This study investigated the effect of changes in organic loading rate (OLR) and feedstock on the volatile fatty acids (VFAs) production and their potential use as a bioengineering management tool to improve stability of anaerobic digesters. Digesters were exposed to one or two changes in OLR using the same or different co-substrates (Fat Oil and Grease waste (FOG) and/or glycerol). Although all the OLR fluctuations produced a decrease in biogas and methane production, the digesters exposed twice to glycerol showed faster recovery towards stable conditions after the second OLR change. This was correlated with the composition of the VFAs produced and their mode of production, from parallel to sequential, resulting in a more efficient recovery from inhibition of methanogenesis. The change in acids processing after the first OLR increase induced a shift in the microbial community responsible of the process optimisation when the digesters were exposed to a subsequent OLR increase with the same feedstock. When the digesters were exposed to an OLR change with a different feedstock (FOG), the recovery took 7d longer than with the same one (glycerol). However, the microbial community showed functional resilience and was able to perform similarly to pre-exposure conditions. Thus, changes in operational conditions can be used to influence microbial community structure for anaerobic digestion (AD) optimisation. Finally, shorter recovery times and increased resilience of digesters were linked to higher numbers of Clostridia incertae sedis XV, suggesting that this group may be a good candidate for AD bioaugmentation to speed up recovery after process instability or OLR increase

Two-channel Kondo physics in tunnel-coupled double quantum dots

We investigate theoretically the possibility of observing two-channel Kondo (2CK) physics in tunnel-coupled double quantum dots (TCDQDs), at both zero and finite magnetic fields; taking the two-impurity Anderson model (2AIM) as the basic TCDQD model, together with effective low-energy models arising from it by Schrieffer-Wolff transformations to second and third order in the tunnel couplings. The models are studied primarily using Wilson's numerical renormalization group. At zero-field our basic conclusion is that while 2CK physics arises in principle provided the system is sufficiently strongly-correlated, the temperature window over which it could be observed is much lower than is experimentally feasible. This finding disagrees with recent work on the problem, and we explain why. At finite field, we show that the quantum phase transition known to arise at zero-field in the two-impurity Kondo model (2IKM), with an essentially 2CK quantum critical point, persists at finite fields. This raises the prospect of access to 2CK physics by tuning a magnetic field, although preliminary investigation suggests this to be even less feasible than at zero field.Comment: 10 pages, 8 figures. Version as published in PR

From mean-motion resonances to scattered planets: Producing the Solar System, eccentric exoplanets and Late Heavy Bombardments

We show that interaction with a gas disk may produce young planetary systems with closely-spaced orbits, stabilized by mean-motion resonances between neighbors. On longer timescales, after the gas is gone, interaction with a remnant planetesimal disk tends to pull these configurations apart, eventually inducing dynamical instability. We show that this can lead to a variety of outcomes; some cases resemble the Solar System, while others end up with high-eccentricity orbits reminiscent of the observed exoplanets. A similar mechanism has been previously suggested as the cause of the lunar Late Heavy Bombardment. Thus, it may be that a large-scale dynamical instability, with more or less cataclysmic results, is an evolutionary step common to many planetary systems, including our own.Comment: 12 pages, 7 figures, submitted to Ap

Digital Textbooks: Reading the Landscape

The migration of books to electronic screens has been accelerating with the introduction of mobile reading on Kindles, i Phones and Sony Readers and the growing power of Google\u27s Book Search engine. The advent of digital textbooks is already upon us. The workshop will survey the current landscape; examine the potential benefits, and confront existing barriers surrounding the technology of digital textbooks. We will examine how other institutions of Higher Education have incorporated this technology into their existing framework and what steps your University or School might take to benefit from the advances being made in the digitization of textbooks

On normed Jordan algebras which are Banach dual spaces

AbstractAlfsen, Shultz, and Størmer have defined a class of normed Jordan algebras called JB-algebras, which are closely related to Jordan algebras of self-adjoint operators. We show that the enveloping algebra of a JB-algebra can be identified with its bidual. This is used to show that a JB-algebra is a dual space iff it is monotone complete and admits a separating set of normal states; in this case the predual is unique and consists of all normal linear functionals. Such JB-algebras (“JBW-algebras”) admit a unique decomposition into special and purely exceptional summands. The special part is isomorphic to a weakly closed Jordan algebra of self-adjoint operators. The purely exceptional part is isomorphic to C(X, M38) (the continuous functions from X into M38)

Triangulating Social Capital Measurement for Turnover Research: Applications to the U.S. Military

In the United States, and around the world, social capital is becoming an intriguing new focus for slowing the declining sense of community and community trust. This strengthening focus on social capital in empirical study has great potential for an important role in U.S. public policy, as policy changes focused on increasing social capital may decrease turnover.Yet, according to researchers, not enough sufficiently tested empirical measures of social capital exist. Combining several existing measures should provide a theoretically informed measurement of social capital for turnover research with application to the U.S. Military. Within this context, this thesis incorporated survey responses into a predictive model of intent to turnover, incorporating a social capital variable, based on the several of its historical measurement studies.This thesis used the social capital variable to add to the body of knowledge and help begin to fill the gap in the research about measuring this little-studied construct with regards to integrating it into a classic turnover model. The broader social sciences discipline has yet to expand upon the study of the social capital variable, in an empirically-sound and theoretically informed manner leading to a clearly-defined, universally-accepted definition of the social capital variable, including all its components. If universally accepted as a necessary component of employee turnover models, this social capital variable will require the beta coefficients for the classic antecedents to be reevaluated. This thesis takes the first steps toward this goal, by adding about one percent to the variance explained, above variance explained by classic turnover antecedents