23 research outputs found
A Search for the Electric Dipole Moment of the Tau-Lepton
Using the ARGUS detector at the e+e- storage ring DORIS II, we have searched
for the real and imaginary part of the electric dipole formfactor d_tau of the
tau lepton in the production of tau pairs at q^2=100 GeV^2. This is the first
direct measurement of this CP violating formfactor. We applied the method of
optimised observables which takes into account all available information on the
observed tau decay products. No evidence for CP violation was found, and we
derive the following results: Re(d_tau)=(1.6+-.9)*10^(-16) ecm and
Im(d_tau)=(-0.2+-0.8)*10^(-16) ecm, where statistical and systematic errors
have been combined.Comment: 8 pages, 5 figures (10 subfigures
Preserved Filamentous Microbial Biosignatures in the Brick Flat Gossan, Iron Mountain, California
A variety of actively precipitating mineral environments preserve morphological evidence of microbial biosignatures. One such environment with preserved microbial biosignatures is the oxidized portion of a massive sulfide deposit, or gossan, such as that at Iron Mountain, California. This gossan may serve as a mineralogical analogue to some ancient martian environments due to the presence of oxidized iron and sulfate species, and minerals that only form in acidic aqueous conditions, in both environments. Evaluating the potential biogenicity of cryptic textures in such martian gossans requires an understanding of how microbial textures form biosignatures on Earth. The iron-oxide-dominated composition and morphology of terrestrial, nonbranching filamentous microbial biosignatures may be distinctive of the underlying formation and preservation processes. The Iron Mountain gossan consists primarily of ferric oxide (hematite), hydrous ferric oxide (HFO, predominantly goethite), and jarosite group minerals, categorized into in situ gossan, and remobilized iron deposits. We interpret HFO filaments, found in both gossan types, as HFO-mineralized microbial filaments based in part on (1) the presence of preserved central filament lumina in smooth HFO mineral filaments that are likely molds of microbial filaments, (2) mineral filament formation in actively precipitating iron-oxide environments, (3) high degrees of mineral filament bending consistent with a flexible microbial filament template, and (4) the presence of bare microbial filaments on gossan rocks. Individual HFO filaments are below the resolution of the Mars Curiosity and Mars 2020 rover cameras, but sinuous filaments forming macroscopic matlike textures are resolvable. If present on Mars, available cameras may resolve these features identified as similar to terrestrial HFO filaments and allow subsequent evaluation for their biogenicity by synthesizing geochemical, mineralogical, and morphological analyses. Sinuous biogenic filaments could be preserved on Mars in an iron-rich environment analogous to Iron Mountain, with the Pahrump Hills region and Hematite Ridge in Gale Crater as tentative possibilities. Key Words: Geobiology—Biosignatures—Filaments—Mars—Microbial fossils. Astrobiology 15, 637–668
Demographics and asset returns: does the dynamics of population ageing matter?
Stock returns, Bond yields, Demographic dynamics, Population ageing, G12, J11, J14,