Evaluation of an anaerobic system for treating poultry mortalities

An anaerobic digestion system was evaluated as an alternative for poultry mortality disposal. The bench-scale system consisted of an upflow anaerobic sludge blanket (UASB) reactor and three leachbeds (LB). The LBs were batch-loaded with dead chickens and sequentially starred at an average interval of 50 days. Only one LB was connected to the UASB to form a closed-loop at any one time. Leachate from the LB was fed to the UASB as influent while effluent from the UASB overflowed to the LB to maintain constant liquid volumes in both reactors. The LB-UASB pair initially functioned as a two-phase system, with the LB serving as the hydrolysis/acidification phase and the UASB serving as the methanogenic phase. Through repeated liquid recycle between the LB and the UASB, the LB eventually accumulated enough methanogens to become methanogenic as well. Leachate concentrations from the methanogenic LB dropped rapidly. When the leachate was no longer able to sustain the UASB at high loading rates (LR), the next LB with another dead chicken was connected to the UASB. Digestion of the mortality was considered complete when methane production rate from the off-line LB became marginal. When digestion in an LB was complete, the fermentation fluid in the LB was reused to start up the next LB. The first cycle ended when digestion in the third LB was complete. Two cycles were completed during this study. The system satisfactorily completed treatment of seven consecutive batches of mortalities in 432 days. The average CH4 yield was 0.679 m(3) (kg dry)(-1) for 0.254 m(3) (kg wet)(-1)]. However timings of the start-up of an LB anti its subsequent connection to the UASB need to be improved to sustain the system at peak treatment efficiency. Alternatively, the system could include a fourth LB to allow more flexibility in scheduling. Additionally a fifth LB reactor would simplify restarting of an LB from its preceding LB being terminated Cost estimates based on systems with one UASB and five LBs ranged from US$118 (10(3) kg live wt sold)(-1) for a 10,000 bird poultry farm to US$28 (103 kg live wt sold)(-1) far a farm with 100,000 chickens

Dirac-harmonic maps from index theory

We prove existence results for Dirac-harmonic maps using index theoretical tools. They are mainly interesting if the source manifold has dimension 1 or 2 modulo 8. Our solutions are uncoupled in the sense that the underlying map between the source and target manifolds is a harmonic map.Comment: 26 pages, no figur

QED With Unequal Charges: A study of spontaneous Zn symmetry breaking

We study two-dimensional QED with unequal charges at finite temperature, and show that there is a phase with a spontaneously broken $Z_n$ symmetry. In spite of this, we were not able to establish the presence of domain walls. The relevance for QCD in higher dimensions is discussed.Comment: 14 Page

Secondary peak on asymmetric magnetization loop of type-II superconductors

Asymmetric magnetization loops with a second peak effect were parameterized by the extended critical state model. The magnetic field distribution in a sample is considered. Expression is suggested for a peak of the critical current density and corresponding depression on field dependence of the depth of surface layer with equilibrium magnetization. These functions determine the width and the asymmetry of a magnetization loop. Asymmetry of the secondary peak height on magnetization branches for increasing and decreasing field is reproduced on the computed magnetization curves.Comment: 6 pages, 2 figures, Equation 6 is modified to be f=0 at B=

Enhanced critical current density of YBa2Cu3Ox films grown on Nd1/3Eu1/3Gd1/3Ba2Cu3Ox with nano-undulated surface morphology

We report a simple and easily controllable method where a nano-undulated surface morphology of Nd1/3Eu1/3Gd1/3Ba2Cu3Ox (NEG) films leads to a substantial increase in the critical current density in superconducting YBa2Cu3Ox (YBCO) films deposited by pulsed laser deposition on such NEG layers. The enhancement is observed over a wide range of fields and temperatures. Transmission electron microscopy shows that such YBCO films possess a high density of localized areas, typically 20 x 20 nm2 in size, where distortion of atomic planes give rotational (2 to 5 degrees) moire patterns. Their distribution is random and uniform, and expected to be the origin of the enhanced flux pinning. Magneto-optical imaging shows that these films have excellent macroscopic magnetic uniformity.Comment: 4 pages, 4 figure

Local threshold field for dendritic instability in superconducting MgB2 films

Using magneto-optical imaging the phenomenon of dendritic flux penetration in superconducting films was studied. Flux dendrites were abruptly formed in a 300 nm thick film of MgB2 by applying a perpendicular magnetic field. Detailed measurements of flux density distributions show that there exists a local threshold field controlling the nucleation and termination of the dendritic growth. At 4 K the local threshold field is close to 12 mT in this sample, where the critical current density is 10^7 A/cm^2. The dendritic instability in thin films is believed to be of thermo-magnetic origin, but the existence of a local threshold field, and its small value are features that distinctly contrast the thermo-magnetic instability (flux jumps) in bulk superconductors.Comment: 6 pages, 6 figures, submitted to Phys. Rev.

Optimal quantum control in nanostructures: Theory and application to generic three-level system

Coherent carrier control in quantum nanostructures is studied within the framework of Optimal Control. We develop a general solution scheme for the optimization of an external control (e.g., lasers pulses), which allows to channel the system's wavefunction between two given states in its most efficient way; physically motivated constraints, such as limited laser resources or population suppression of certain states, can be accounted for through a general cost functional. Using a generic three-level scheme for the quantum system, we demonstrate the applicability of our approach and identify the pertinent calculation and convergence parameters.Comment: 7 pages; to appear in Phys. Rev.

Long Range Hops and the Pair Annihilation Reaction A+A->0: Renormalization Group and Simulation

A simple example of a non-equilibrium system for which fluctuations are important is a system of particles which diffuse and may annihilate in pairs on contact. The renormalization group can be used to calculate the time dependence of the density of particles, and provides both an exact value for the exponent governing the decay of particles and an epsilon-expansion for the amplitude of this power law. When the diffusion is anomalous, as when the particles perform Levy flights, the critical dimension depends continuously on the control parameter for the Levy distribution. The epsilon-expansion can then become an expansion in a small parameter. We present a renormalization group calculation and compare these results with those of a simulation.Comment: As-published version; two significant errors fixed, two references adde

Phosphorylation of focal adhesion kinase on tyrosine 194 by Met leads to its activation through relief of autoinhibition

Focal adhesion kinase (FAK) has a crucial role in integration of signals from integrins and growth factor receptors. In this study, we demonstrate that growth factor receptors including hepatocyte growth factor receptor Met, epidermal growth factor receptor, and platelet-derived growth factor receptor directly phosphorylate FAK on Tyr194 in the FERM domain (band 4.1 and ezrin/radixin/moesin homology domain). Upon binding to Met or phosphoinositides, FAK may undergo conformational changes, which renders Tyr194 accessible for phosphorylation. Substitution of Tyr194 with Phe significantly suppresses the activation of FAK by Met. In contrast, substitution of Tyr194 with Glu (Y194E substitution) leads to constitutive activation of FAK. The phosphorylation of FAK on Tyr194 may cause conformational changes in the FERM domain, which disrupts the intramolecular inhibitory interaction between the FERM and kinase domains of FAK. Moreover, substitution of the basic residues in the (216)KAKTLRK(222) patch in the FERM domain with Ala antagonizes the effect of the Y194E substitution on FAK activation, thus suggesting that the interactions between the phosphorylated Tyr194 and the basic resides in the (216)KAKTLRK(222) patch may allow FAK to be activated through relief of its autoinhibition. Collectively, this study provides the first example to explain how FAK is activated by receptor tyrosine kinases. Oncogene (2011) 30, 153-166; doi:10.1038/onc.2010.398; published online 30 August 201

Self-replication and evolution of DNA crystals

Is it possible to create a simple physical system that is capable of replicating itself? Can such a system evolve interesting behaviors, thus allowing it to adapt to a wide range of environments? This paper presents a design for such a replicator constructed exclusively from synthetic DNA. The basis for the replicator is crystal growth: information is stored in the spatial arrangement of monomers and copied from layer to layer by templating. Replication is achieved by fragmentation of crystals, which produces new crystals that carry the same information. Crystal replication avoids intrinsic problems associated with template-directed mechanisms for replication of one-dimensional polymers. A key innovation of our work is that by using programmable DNA tiles as the crystal monomers, we can design crystal growth processes that apply interesting selective pressures to the evolving sequences. While evolution requires that copying occur with high accuracy, we show how to adapt error-correction techniques from algorithmic self-assembly to lower the replication error rate as much as is required