Complex refractive index, single scattering albedo, and mass absorption coefficient of secondary organic aerosols generated from oxidation of biogenic and anthropogenic precursors

Refractive index and optical properties of biogenic and anthropogenic secondary organic aerosol (SOA) particles were investigated. Aerosol precursors, namely longifolene, α-pinene, 1-methylnaphthalene, phenol, and toluene were oxidized in a Teflon chamber to produce SOA particles under different initial hydrocarbon concentrations and hydroxyl radical sources, reflecting exposures to different levels of nitrogen oxides (NOx). The real and imaginary components (n and k, respectively) of the refractive index at 375 nm and 632 nm were determined by Mie theory calculations through an iterative process, using the χ2 function to evaluate the fitness of the predicted optical parameters with the measured scattering, absorption, and extinction coefficients from a Photoacoustic Extinctiometer and Cavity Attenuated Phase Shift Spectrometer. Single scattering albedo (SSA) and bulk mass absorption coefficient (MAC) at 375 nm were calculated. SSA values of SOA particles from biogenic precursors (longifolene and α-pinene) were ∼0.98–0.99 (∼6.3% uncertainty), reflecting purely scattering aerosols regardless of the NOx regime. However, SOA particles from aromatic precursors were more absorbing and displayed NOx-dependent SSA values. For 1-methylnaphthalene SOA particles, SSA values of 0.92–0.95 and ∼0.75–0.90 (∼6.1% uncertainty) were observed under intermediate- and high-NOx conditions, respectively, reflecting the absorbing effects of SOA particles and NOx chemistry for this aromatic system. In mixtures of longifolene and phenol or longifolene and toluene SOA under intermediate- and high-NOx conditions, k values of the aromatic-related component of the SOA mixture were higher than that of 1-methylnaphthalene SOA particles. With the increase in OH exposure, kphenol decreased from 0.10 to 0.02 and 0.22 to 0.05 for intermediate- and high-NOx conditions, respectively. A simple relative radiative forcing calculation for urban environments at λ = 375 nm suggests the influence of absorbing SOA particles on relative radiative forcing at this wavelength is most significant for aerosol sizes greater than 0.4 µm. Copyright © 2019 American Association for Aerosol Research</p

Probable Displacement of Riffle-Dwelling Invertebrates by the Introduced Rusty Crayfish, \u3ci\u3eOrconectes Rusticus\u3c/i\u3e (Decapoda: Cambaridae) in a North-Central Wisconsin Stream

The rapid northward range expansion of the rusty crayfish, Orconectes rusticus, and its negative effects on Wisconsin lakes have been the subjects of intense study throughout the last fifteen years. In this study, we investigated the possible impact of rusty crayfish on the benthic macroinvertebrate community structure of the Prairie River in north-central Wisconsin. Rusty crayfish and other invertebrates were collected during August and September, 1994, from three sections of the Prairie River. Rusty crayfish relative abundance increased significantly from the upper to middle, and middle to lower sections; and correlated negatively with a significant 77% decrease in total density of aquatic invertebrates between sections. Mean density of all important invertebrate families and trophic guilds decreased significantly between the upper and lower sections. Due to the similarity of most environmental conditions between river sections, decrease of invertebrates is attributed to the increased abundance of rusty crayfish and its interactions with the native rouna. Our results suggest that a high abundance of rusty crayfish may negatively impact Wisconsin lotic systems

Deficiency of annexins A5 and A6 induces complex changes in the transcriptome of growth plate cartilage but does not inhibit the induction of mineralization

Initiation of mineralization during endochondral ossification is a multistep process and has been assumed to correlate with specific interactions of annexins A5 and A6 and collagens. However, skeletal development appears to be normal in mice deficient for either A5 or A6, and the highly conserved structures led to the assumption that A5 and A6 may fulfill redundant functions. We have now generated mice deficient of both proteins. These mice were viable and fertile and showed no obvious abnormalities. Assessment of skeletal elements using histologic, ultrastructural, and peripheral quantitative computed tomographic methods revealed that mineralization and development of the skeleton were not significantly affected in mutant mice. Otherwise, global gene expression analysis showed subtle changes at the transcriptome level of genes involved in cell growth and intermediate metabolism. These results indicate that annexins A5 and A6 may not represent the essential annexins that promote mineralization in vivo

Healthcare Student Collegiate Honors Decision-Making: A Grounded Theory

This qualitative study explored high aptitude healthcare students’ decision-making surrounding collegiate honors program participation. The topic of decision-making was relevant; according the National Collegiate Honors Council (2014-2015) the mean four-year honors program completion rate is less than 50% . The primary research question explored how students’ values, knowledge, and experiences influenced decisions to participate in a collegiate honors program. Twenty-five students’ were interviewed representing ten different healthcare professions. The transcribed narratives were analyzed using a constructivist grounded theory method. The result was a model, grounded in the data, which identified the factors associated with decisions to join, decline or drop the program. Four major themes comprise the Model of Healthcare Student Collegiate Honors Decision-Making: Pre-college experiences, valuing honors, selective admission, and confounding factors. High school pre-college experiences in honors courses or the National Honors Society were linked directly to pre-selection for program admission. Valuing honors curricula and pre-selection for admission were associated with joining the program. Knowledge of confounding factors which led students’ to decline or drop the program were: Major demands, the stress of the program, lack of ethnic diversity, cost, and concerns about the program lowering their cumulative grade point average. The generated theory identified modifiable factors that can be addressed to improve program admission, retention and completion rates. The study also captured healthcare students’ innovative ideas on how to overcome barriers to program completion through the integrating interprofessional education (IPE) into liberal arts based honors coursewor

Genetic population structure of harbour seals in the United Kingdom and neighbouring waters

Natural Environment Research Council (GrantNumber(s): SMRU1001; Grant recipient(s): Ailsa Hall)1.  In the United Kingdom (UK), several harbour seal (Phoca vitulina) populations have been declining over the past decade. In order to understand the effect of these changes in abundance, this study seeks to determine the population structure of harbour seals in the UK, and in Scotland in particular, on a wider and finer spatial scale than has previously been reported. 2.  Harbour seals were genotyped from 18 different localities throughout the UK and neighbouring localities in mainland Europe, at 12 microsatellite loci. Results from Bayesian and frequency based tests of population structure suggested an initial structural division into two main groups consisting of localities in northern UK and southern UK-mainland Europe, respectively. 3.  These two clusters were further divided into four geographically distinct genetic clusters. 4.  An overall agreement between the genetic results and the existing management areas for UK harbour seals was observed, but it is also clear that an adaptive management approach should be adopted, in which the delineation of the current management areas is maintained until further genetic and ecological information has been accumulated and analysed.Publisher PDFPeer reviewe

The Multiple Temporalities of a Burial Monument: The Tumulus at Hrib

Tumuli are often analyzed as a coherent whole in the hope of discerning patterns that indicate social processes inhered in the monument. However, in the search for patterning too often the mound is analytically flattened, and examined as if it was created all at once with a coherent plan. In the following, I will focus on the tumulus at Hrib, an Iron Age tumulus in the Bela krajina region of Slovenia, and undertake a multiscalar analysis that considers temporal distinctions, interment ritual, grave goods, and gender to draw more nuanced conclusions about the social activities that led to the formation of this tumulus. The first level of analysis is the scale of individual ritual, where choices about how to appropriately dispose of and adorn the body are negotiated. Second is the social context of death and burial, which takes place at an intra-generational scale – that is, how death may resonate with the living community, and how the social relations of the living are affected by death. The final scale is the consideration of the tumulus as a whole at a multi-generational scale, and how cemeteries are places with continuous social impact, even when distinct memories of those interred have faded. This shift in the scale of analysis of the tumulus at Hrib illuminates that social distinctions were marked according to an external/internal binary, where material culture and social practices, including grave goods and funerary ritual, expressed social differences internally, while the external appearance of the mound projected unity