Peroxy radicals in the summer free troposphere: seasonality and potential for heterogeneous loss

The sum of peroxy radicals (HO2+ΣiRiO2) and supporting trace gases were measured on the Jungfraujoch (3580 m a.s.l.) during the late summer of 2005. The period was marked by extended times of heavy snow which led to reduction in the observed peroxy radicals during the snowy periods that was greater than the concomitant reduction in j(O1D). In the limit a first order loss rate of 0.0063 s−1 can be derived for the peroxy radical loss in the snowy conditions that could be potentially ascribed to a heterogenous loss process. On snow free days photolysis of HCHO is shown to be a significant peroxy radical source. The seasonal trends of the peroxy radical concentrations have been mapped from the winter to summer transition in line with previous experiments. Net ozone production in late summer at the Jungfraujoch was net neutral to marginally ozone destructive. A value of 28±4 pptv is calculated for the ozone compensation point for the snow free days.ISSN:1680-7375ISSN:1680-736

On the production of26A1 in the early solar system by low-energy oxygen cosmic rays

Clayton & Jin have proposed that the high abundance of 26Al found in meteorites was produced by cosmic rays in the early solar system through the 12C(16O,x)26Ales reaction. We have measured the yield of 26A1 in the ground state (i.e., 26Algs) from this reaction and find that, if this mechanism produced the meteoritic 26Al, a substantial fraction of the solar system oxygen must have entered the solar system as low-energy cosmic rays. This does not seem plausible. If the proto-Sun itself was the source of the oxygen cosmic rays, they must have carried off some 5% of the power of the protosolar wind for 1 Myr. This too seems unlikely. Although we do not address the role of other cosmic-ray species in the production of26 Al, it appears that 26A1 was produced in a stellar environment, and not by cosmic rays

Trace amine receptor in GtoPdb v.2023.1

Trace amine-associated receptors were discovered from a search for novel 5-HT receptors [9], where 15 mammalian orthologues were identified and divided into two families. The TA1 receptor (nomenclature as agreed by the NC-IUPHAR Subcommittee for the Trace amine receptor [58]) has affinity for the endogenous trace amines tyramine, β-phenylethylamine and octopamine in addition to the classical amine dopamine [9]. Emerging evidence suggests that TA1 is a modulator of monoaminergic activity in the brain [94] with TA1 and dopamine D2 receptors shown to form constitutive heterodimers when co-expressed [30]. In addition to trace amines, receptors can be activated by amphetamine-like psychostimulants, and endogenous thyronamines

Trace amine receptor (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

Trace amine-associated receptors were discovered from a search for novel 5-HT receptors [9], where 15 mammalian orthologues were identified and divided into two families. The TA1 receptor (nomenclature as agreed by the NC-IUPHAR Subcommittee for the Trace amine receptor [53]) has affinity for the endogenous trace amines tyramine, β-phenylethylamine and octopamine in addition to the classical amine dopamine [9]. Emerging evidence suggests that TA1 is a modulator of monoaminergic activity in the brain [90] with TA1 and dopamine D2 receptors shown to form constitutive heterodimers when co-expressed [28]. In addition to trace amines, receptors can be activated by amphetamine-like psychostimulants, and endogenous thyronamines

Coupled oscillators as models of phantom and scalar field cosmologies

We study a toy model for phantom cosmology recently introduced in the literature and consisting of two oscillators, one of which carries negative kinetic energy. The results are compared with the exact phase space picture obtained for similar dynamical systems describing, respectively, a massive canonical scalar field conformally coupled to the spacetime curvature, and a conformally coupled massive phantom. Finally, the dynamical system describing exactly a minimally coupled phantom is studied and compared with the toy model.Comment: 18 pages, LaTeX, to appear in Physical Review

The molecular ecology of Microcystis sp. blooms in the San Francisco Estuary

Harmful blooms of the cyanobacterium Microcystis sp. have become increasingly pervasive in the San Francisco Estuary Delta (USA) since the early 2000s and their rise has coincided with substantial decreases in several important fish species. Direct and indirect effects Microcystis blooms may have on the Delta food web were investigated. The Microcystis population was tracked for 2 years at six sites throughout the Delta using quantitative PCR. High-throughput amplicon sequencing and colony PCR sequencing revealed the presence of 10 different strains of Microcystis, including 6 different microcystin-producing strains. Shotgun metagenomic analysis identified a variety of Microcystis secondary metabolite pathways, including those for the biosynthesis of: aeruginosin, cyanopeptolin, microginin, microviridin and piricyclamide. A sizable reduction was observed in microbial community diversity during a large Microcystis bloom (H′ = 0.61) relative to periods preceding (H′ = 2.32) or following (H′ = 3.71) the bloom. Physicochemical conditions of the water column were stable throughout the bloom period. The elevated abundance of a cyanomyophage with high similarity to previously sequenced isolates known to infect Microcystis sp. was implicated in the bloom's collapse. Network analysis was employed to elucidate synergistic and antagonistic relationships between Microcystis and other bacteria and indicated that only very few taxa were positively correlated with Microcystis

Matter wave solitons at finite temperatures

We consider the dynamics of a dark soliton in an elongated harmonically trapped Bose-Einstein condensate. A central question concerns the behavior at finite temperatures, where dissipation arises due to the presence of a thermal cloud. We study this problem using coupled Gross-Pitaevskii and $N$-body simulations, which include the mean field coupling between the condensate and thermal cloud. We find that the soliton decays relatively quickly even at very low temperatures, with the decay rate increasing with rising temperature.Comment: 6 pages, 2 figures, submitted to the Proceedings of QFS '0