Serological survey of Australian native reptiles for exposure to ranavirus

Ranaviruses have been isolated from many ectothermic vertebrates, and serological surveys of both amphibians and reptiles have shown the presence of ranaviral antibodies in a proportion of these populations. An enzyme-linked immunosorbent assay (ELISA) was developed to measure serum antibodies against ranavirus in Australian reptiles. The ELISA was validated with serum from challenge trials with Bohle iridovirus (BIV) in 6 reptilian species. A preliminary serosurvey of northern Queensland riparian reptile fauna (saw-shelled turtles Myuchelys latisternum, Krefft's river turtles Emydura macquarii krefftii, freshwater crocodiles Crocodylus johnstoni, as well as the snakes Boiga irregularis, Dendrelaphis punctulatus, Tropidonophis mairii, Morelia spilota, Liasis childreni and L. fuscus) revealed evidence of past exposure to Bohle iridoviral antigens in part of the population at several locations sampled. Furthermore, in Krefft's river turtles and freshwater crocodiles, a statistically significant trend was apparent for larger reptiles to be more likely to have BIV-reactive sera than smaller individuals. The use of adult tortoise populations as sentinels can assist in monitoring the presence of BIV in northern Australian freshwater streams, and thereby the potential dangers to native fauna from this agent

Lessons from QCD2(N→∞)QCD_2 (N\to\infty): Vacuum structure, Asymptotic Series, Instantons and all that

We discuss two dimensional $QCD (N_c\to\infty)$ with fermions in the fundamental as well as adjoint representation. We find factorial growth $\sim (g^2N_c\pi)^{2k}\frac{(2k)!(-1)^{k-1}}{(2 \pi)^{2k}}$ in the coefficients of the large order perturbative expansion. We argue that this behavior is related to classical solutions of the theory, instantons, thus it has nonperturbative origin. Phenomenologically such a growth is related to highly excited states in the spectrum. We also analyze the heavy-light quark system $Q\bar{q}$ within operator product expansion (which it turns out to be an asymptotic series). Some vacuum condensates \la\bar{q}(x_{\mu}D_{\mu})^{2n}q\ra\sim (x^2)^n\cdot n! which are responsible for this factorial growth are also discussed. We formulate some general puzzles which are not specific for 2D physics, but are inevitable features of any asymptotic expansion. We resolve these apparent puzzles within $QCD_2$ and we speculate that analogous puzzles might occur in real 4-dimensional QCD as well.Comment: latex, 26 pages. A final version to appear in Phys. Rev.

Vortex Rings in two Component Bose-Einstein Condensates

We study the structure of the vortex core in two-component Bose-Einstein condensates. We demonstrate that the order parameter may not vanish and the symmetry may not be restored in the core of the vortex. In this case such vortices can form vortex rings known as vortons in particle physics literature. In contrast with well-studied superfluid $^4He$, where similar vortex rings can be stable due to Magnus force only if they move, the vortex rings in two-component BECs can be stable even if they are at rest. This beautiful effect was first discussed by Witten in the cosmic string context, where it was shown that the stabilization occurs due to condensation of the second component of the field in the vortex core. This second condensate trapped in the core may carry a current along the vortex ring counteracting the effect of string tension that causes the loop to shrink. We speculate that such vortons may have been already observed in the laboratory. We also speculate that the experimental study of topological structures in BECs can provide a unique opportunity to study cosmology and astrophysics by doing laboratory experiments.Comment: 21 pages, 2 figure

First-order cosmological phase transitions in the radiation dominated era

We consider first-order phase transitions of the Universe in the radiation-dominated era. We argue that in general the velocity of interfaces is non-relativistic due to the interaction with the plasma and the release of latent heat. We study the general evolution of such slow phase transitions, which comprise essentially a short reheating stage and a longer phase equilibrium stage. We perform a completely analytical description of both stages. Some rough approximations are needed for the first stage, due to the non-trivial relations between the quantities that determine the variation of temperature with time. The second stage, instead, is considerably simplified by the fact that it develops at a constant temperature, close to the critical one. Indeed, in this case the equations can be solved exactly, including back-reaction on the expansion of the Universe. This treatment also applies to phase transitions mediated by impurities. We also investigate the relations between the different parameters that govern the characteristics of the phase transition and its cosmological consequences, and discuss the dependence of these parameters with the particle content of the theory.Comment: 38 pages, 3 figures; v2: Minor changes, references added; v3: several typos correcte

Recovery of ammonia from anaerobically digested manure using gas-permeable membranes

ABSTRACT Nitrogen (N) can be recovered from different types of wastewaters. Among these wastewaters, anaerobically digested swine manure (digestate) has the highest N content in ammonia form (NH3). It is desirable to reduce N in digestate effluents to safely incorporate them in arable soil in N vulnerable zones (NVZ) and to mitigate NH3 emissions during N land application. Additional benefit is to minimize inhibition of the anaerobic process by removing NH3 during the anaerobic digestion process. This work aimed to apply the gas-permeable membrane technology to evaluate ammonia (NH3) recovery from high-ammonia digested swine manure. Anaerobically digested swine manure with NH4+ content of 4,293 mg N L−1 was reduced by 91 % (to 381 mg N L−1) during the 32-day experiment. Although the results showed a total N recovery efficiency of 71 %, it is possible to increase this recovery efficiency to > 90 % by adjusting the area of the membrane system to match the high free ammonia concentration (FA) in digested swine manure. Moreover, final digestate pH and alkalinity were kept around 8.1 and 8,923 mgCaCO3 L−1, which are convenient for the anaerobic process or incorporation in arable soil when the process is finished

Partial nitritation of swine wastewater in view of its coupling with the anammox process

Partial nitritation (PN) of swine wastewater was investigated in a sequencing batch reactor (SBR) using a high performance nitrifying sludge (HPNS). Characteristics of the wastewater used were low content of biodegradable organic carbon and high alkalinity-to-ammonium ratio. Process temperature was 32°C. Target oxidation of ammonium nitrogen (NH4-N) to nitrite nitrogen (NO2-N) was 57% (1.32 g NO2-N g-1 NH4-N), which corresponds with the stoichiometry of the anammox reaction. This target was successfullly achieved just by controlling the inflow rate and corresponding N loading rate (NLR). An average NLR of 1.47 g NH4-N L-1 d- 1 was applied to the PN-SBR during a period of 70 days. The NO2-N production rate obtained was 0.91 g L- 1 d-1. No nitrate was produced. The PN effluent contained 1.38 g NO2-N g-1 NH4-N, which was within 5% of the target ratio. Under steady state conditions, the pH was shown as a good indicator of the PN process performance. Furthermore, in a second SBR the anammox process was effectively applied to the PN effluent attaining an N conversion rate of 0.36 g N L- 1 h-1 (14.3 mg N g-1 VSS h-1).Postprint (published version

Anammox treatment of swine wastewater using immobilized technology

ppropriate land application of manure nitrogen at agronomic rates must be assured in order to preserve environmental quality of agricultural ecosystems, atmosphere, and water resources. When land is limiting, the combined bioprocess of nitrification-denitrification (NDN) has often been considered for the removal of nitrogen, implying the conversion of ammoniumPostprint (published version

Partial nitritation of swine wastewater in view of its coupling with the anammox process

Partial nitritation (PN) of swine wastewater was investigated in a sequencing batch reactor (SBR) using a high performance nitrifying sludge (HPNS). Characteristics of the wastewater used were low content of biodegradable organic carbon and high alkalinity-to-ammonium ratio. Process temperature was 32°C. Target oxidation of ammonium nitrogen (NH4-N) to nitrite nitrogen (NO2-N) was 57% (1.32 g NO2-N g-1 NH4-N), which corresponds with the stoichiometry of the anammox reaction. This target was successfullly achieved just by controlling the inflow rate and corresponding N loading rate (NLR). An average NLR of 1.47 g NH4-N L-1 d- 1 was applied to the PN-SBR during a period of 70 days. The NO2-N production rate obtained was 0.91 g L- 1 d-1. No nitrate was produced. The PN effluent contained 1.38 g NO2-N g-1 NH4-N, which was within 5% of the target ratio. Under steady state conditions, the pH was shown as a good indicator of the PN process performance. Furthermore, in a second SBR the anammox process was effectively applied to the PN effluent attaining an N conversion rate of 0.36 g N L- 1 h-1 (14.3 mg N g-1 VSS h-1)

Anammox treatment of swine wastewater using immobilized technology

ppropriate land application of manure nitrogen at agronomic rates must be assured in order to preserve environmental quality of agricultural ecosystems, atmosphere, and water resources. When land is limiting, the combined bioprocess of nitrification-denitrification (NDN) has often been considered for the removal of nitrogen, implying the conversion of ammoniu

Streamlined ammonia removal from wastewater using biological deammonification process

In this work we evaluated biological deammonification process to more economically remove ammonia from livestock wastewater. The process combines partial nitritation (PN) and anammox. The anammox is a biologically mediated reaction that oxidizes ammonia (NH4+) and releases di-nitrogen gas (N2) under anaerobic conditions using nitrite (NO2-) as the electron acceptor. We tested two deammonification configurations: 1) a two-stage process (PN in one tank and anammox in another), and 2) a one-stage deammonification process (PN and anammox in a single tank). In both cases, a high performance nitrifying sludge, HPNS (NRRL B-50298) was used for PN and Brocadia caroliniensis (NRRL B-50286) was used for the anammox reaction. The two-tank process was carried out using sequencing batch reactors (SBR), one aerated and the other anaerobic, at 32ºC water temperature. The single-tank process was carried out in an aerated vessel operated under continuous flow. It contained biofilm plastic carriers at 30% v/v packing ratio that were fluidized by the aeration. The process water temperature was 22oC and DO generally below 0.5 mg/L. In the PN-SBR reactor, the NO2- production rate obtained at was 0.91 g NO2--N/L-reactor/d. The PN effluent contained 1.38 g NO2--N/g NH4+-N, which was within 5% of the target oxidation of ammonium to nitrite of 57%, which corresponds with the reaction ratio of anammox. In the second SBR, the anammox process was effectively applied to the PN effluent, attaining a nitrogen conversion rate of 0.36 g N/L-reactor/day (14.3 mg N/g VSS/ h) and anammox stoichiometric ratios of 1.00:1.32:0.15. For the single-tank deammonification, total N removal rates of 0.75 to 1.0 g N/L-reactor/day were obtained for both synthetic and swine wastewater. The stoichiometry of the reaction obtained in the single-tank process was consistent with deammonification process theory combining partial nitritation and anammox: NH4+ + 0.88 O2 ¿ 0.44 N2 + 0.11 NO3- + 1.43 H2O + 1.14 H+. Compared to conventional nitrification/denitrification, a partial nitritation/anammox pathway (deammonification process) can reduce 58% of the oxygen requirement to biologically eliminate the ammonia from wastewater. Thus, it offers the potential to reduce the cost of treatment of ammonia in livestock wastewaters and other effluents containing high ammonia nitrogen.Postprint (published version