Systematics of Unionicola Laurentiana, N.Sp., and U. Nearctica, N. Sp., Sponge-Associated Hydracarina (Parasitengona: Unionicolidae) from North America

Author Institution: Department of Biology, Saint Lawrence University; Zoologisch Laboratorium, Universiteit van Amsterdam, The NetherlandsThe sponge-associated Hydracarina of North America historically have been considered conspecific with the European species Unionicola crassipes (Miiller 1776). Ratio diagrams based on numerous morphological characteristics distinguish the North American crassipes-like mites from U. crassipes and two North American species are described. Unionicola laurentiana, n.sp., occurs in the Laurentian Great Lakes and St. Lawrence River basins. U. nearctica, n.sp., occurs in that region and its range extends across Canada from Ontario to British Columbia

Electron Photodetachment from Aqueous Anions. III. Dynamics of Geminate Pairs Derived from Photoexcitation of Mono- vs. Poly- atomic Anions

Photostimulated electron detachment from aqueous inorganic anions is the simplest example of solvent-mediated electron transfer. Here we contrast the behavior of halide anions with that of small polyatomic anions, such as pseudohalide anions (e.g., HS-) and common polyvalent anions (e.g., SO32-). Geminate recombination dynamics of hydrated electrons generated by 200 nm photoexcitation of aqueous anions (I-, Br-, OH-, HS-, CNS-, CO32-, SO32-, and Fe(CN)64-) have been studied. Prompt quantum yields for the formation of solvated, thermalized electrons and quantum yields for free electrons were determined. Pump-probe kinetics for 200 nm photoexcitation were compared with kinetics obtained at lower photoexcitation energy (225 nm or 242 nm) for the same anions, where possible. Free diffusion and mean force potential models of geminate recombination dynamics were used to analyze these kinetics. These analyses suggest that for polyatomic anions (including all polyvalent anions studied) the initial electron distribution has a broad component, even at relatively low photoexcitation energy. There seem to be no well-defined threshold energy below which the broadening of the distribution does not occur, as is the case for halide anions. Direct ionization to the conduction band of water is the most likely photoprocess broadening the electron distribution. Our study suggests that halide anions are in the class of their own; electron photodetachment from polyatomic, especially polyvalent, anions follows a different set of rules.Comment: to be submitted to J. Phys. Chem. A; 28 pages, 5 figs + Supplemen

A longitudinal study on the progression of myopia

A longitudinal study on the progression of myopi

Transient x-ray absorption spectroscopy of hydrated halogen atom

Time-resolved x-ray absorption spectroscopy monitors the transient species generated by one-photon detachment of an electron from aqueous bromide. Hydrated bromine atoms with a lifetime of ca. 17 ns were observed, nearly half of which react with excess Br- to form Br2-. The K-edge spectra of the Br atom and Br2- anion exhibit distinctive resonant transitions that are absent for the Br- precursor. The absorption spectra indicate that the solvent shell around a Br0 atom is defined primarily by hydrophobic interactions, in agreement with a Monte Carlo simulation of the solvent structure.Comment: 6 pages, 4 figures + supplement, will be submitted to PR

Geminate recombination of electrons generated by above-the-gap (12.4 eV) photoionization of liquid water

The picosecond geminate recombination kinetics for hydrated electrons generated by 200 nm two photon absorption (12.4 eV total energy) has been measured in both light and heavy water. The geminate kinetics are observed to be almost identical in both H2O and D2O. Kinetic analysis based upon the independent reaction time approximation indicates that the average separation between the electron and its geminate partners in D2O is 13% narrower than in H2O (2.1 nm vs. 2.4 nm). These observations suggest that, even at this high ionization energy, autoionization of water competes with direct ionization.Comment: 10 pages + 2 figures, submitted to Chem. Phys. Letter

Security of attachment to spouses in late life: Concurrent and prospective links with cognitive and emotional wellbeing

Social ties are powerful predictors of late-life health and well-being. Although many adults maintain intimate partnerships into late life, little is known about mental models of attachment to spouses and how they influence aging. A total of 81 elderly heterosexual couples (162 individuals) were interviewed to examine the structure of attachment security to their partners; respondents also completed measures of cognition and well-being concurrently and 2.5 years later. Factor analysis revealed a single factor for security of attachment. Higher security was linked concurrently with greater marital satisfaction, fewer depressive symptoms, better mood, and less frequent marital conflicts. Greater security predicted lower levels of negative affect, less depression, and greater life satisfaction 2.5 years later. For women, greater security predicted better memory 2.5 years later and attenuated the link between frequency of marital conflict and memory deficits. Late in life, mental models of attachment to partners are linked to well-being concurrently and over time