Beyond the Edge and in Between: (Re)conceptualizing the Rural–Urban Interface as Meaning–Model–Metaphor

As examinations of the rural–urban interface move beyond a focus on the rural or urban fringe as a location and move toward examining the patterns and processes that both divide and link rural and urban places, a broader (re)conceptualization of the rural–urban interface becomes increasingly important. Thus far the question of boundaries and interfaces between so-called urban and rural locales has mostly revolved around where and when such boundaries occur (including significant coverage of the differences and conflicts between urban vs. rural people), rather than asking what physical or social functions are being served by the rural–urban interface itself. In response, I (re)frame the rural–urban interface not only as a boundary between two distinct spaces but also as a conduit, a place of exchange, and a flux point between them. Using a particular case of contested ecologies in the exurban Sierra Nevada foothills of California, I (re)conceptualize the rural–urban interface as meaning, model, and metaphor (MMM), situating contrasting people and places in an ongoing negotiation of place and environmental meaning along the (ex)urbanizing edge. Although the differences between rural and urban are increasingly unclear, the division continues to be compelling from environmental and sociopolitical standpoints. I argue that (perceived) boundaries are instrumental in understanding physical–material change and for mitigating social conflicts occurring across them. As such, attention to the patterns, processes, and flows that connect or separate rural and urban areas is critical to forging effective and long-lasting solutions to contemporary social, economic, and environmental problems.     

The Abiotic Nitrite Oxidation by Ligand-Bound Manganese (III): The Chemical Mechanism

Aquatic Geochemistry - Given their environmental abundances, it has been long hypothesized that geochemical interactions between reactive forms of manganese and nitrogen may play important roles in...     

Scenario analysis for assessing the impact of hydraulic fracturing on stream low flows using the SWAT model

Scientists and water users are concerned about the potential impact on water resources, particularly during low-flow periods, of freshwater withdrawals for hydraulic fracturing (fracking). Therefore, the objective of this paper is to assess the potential impact of hydraulic fracturing on water resources in the Muskingum watershed of Eastern Ohio, USA, especially due to the trend of increased withdrawals for hydraulic fracking during drought years. The Statistical Downscaling Model (SDSM) was used to generate 30 years of plausible future daily weather series in order to capture the possible dry periods. The data generated were incorporated in the Soil and Water Assessment Tool (SWAT) to examine the level of impact due to fracking at various scales. Analyses showed that water withdrawal due to hydraulic fracking had a noticeable impact, especially during low-flow periods. Clear changes in the 7-day minimum flows were detected among baseline, current and future scenarios when the worst-case scenario was implemented. The headwater streams in the sub-watersheds were highly affected, with significant decrease in 7-day low flows. The flow alteration in hydrologically-based (7Q10, i.e. 7-day 10-year low flow) or biologically-based (4B3 and 1B3) design flows due to hydraulic fracking increased with decrease in the drainage area, indicating that the relative impact may not be as great for higher order streams. Nevertheless, change in the annual mean flow was limited to 10%.     

Insight into sediment transport processes on saline rangeland hillslopes using three‐dimensional soil microtopography changes

In arid and semi‐arid rangeland environments, an accurate understanding of runoff generation and sediment transport processes is key to developing effective management actions and addressing ecosystem response to changes. Yet, many primary processes (namely sheet and splash and concentrated flow erosion, as well as deposition) are still poorly understood due to a historic lack of measurement techniques capable of parsing total soil loss into these primary processes. Current knowledge gaps can be addressed by combining traditional erosion and runoff measurement techniques with image‐based three‐dimensional (3D) soil surface reconstructions. In this study, data (hydrology, erosion and high‐resolution surface microtopography changes) from rainfall simulation experiments on 24 plots in saline rangelands communities of the Upper Colorado River Basin were used to improve understanding on various sediment transport processes. A series of surface change metrics were developed to quantify and characterize various erosion and transport processes (e.g. plot‐wide versus concentrated flow detachment and deposition) and were related to hydrology and biotic and abiotic land surface characteristics. In general, erosivity controlled detachment and transport processes while factors modulating surface roughness such as vegetation controlled deposition. The extent of the channel network was a positive function of slope, discharge and vegetation. Vegetation may deflect runoff in many flow paths but promoted deposition. From a management perspective, this study suggests that effective runoff soil and salt load reduction strategies should aim to promote deposition of transported sediments rather than reducing detachment which might not be feasible in these resource‐limited environments. Copyright © 2016 John Wiley & Sons, Ltd.     

Geographic Polarization,Partisan Voting,And The Battle Over Same‐Sex Marriage Within The Culture War

Geographic polarization arises when partisan, or like‐minded, voters live in enclaves separate from voters of differing partisan behavior. Research studies at multiple scales of analysis suggest that geographic polarization most typically occurs regarding partisan voting behavior; however, few studies have analyzed polarization with a focus on policy preferences. This research examines same‐sex marriage policy through two statewide issues that shared the presidential election ballot in 2004. The results of that presidential election and these two ballot initiatives are examined in Cincinnati, Ohio, and counties in its surrounding Metropolitan Statistical Area (MSA) in both Ohio and Kentucky. A geographically polarized relationship was found between partisan results and same‐sex marriage results. In addition, the findings suggest that despite a close link between partisan voting and issue voting on same‐sex marriage, spatial clustering (geographic polarization) was identified of those who voted differently from their fellow partisans.     

Geology of the Renard 65 kimberlite pipe,Québec,Canada

Renard 65, a diamondiferous pipe in the Neoproterozoic Renard kimberlite cluster (Québec, Canada), is a steeply-dipping and downward-tapering diatreme comprised of three pipe-filling units: kimb65a, kimb65b, and kimb65d. The pipe is surrounded by a marginal and variably-brecciated country rock aureole and is crosscut by numerous hypabyssal dykes: kimb65c. Extensive petrographic and mineralogical characterization of over 700 m of drill core from four separate drill holes, suggests that Renard 65 is a Group I kimberlite, mineralogically classified as phlogopite kimberlite and serpentine-phlogopite kimberlite. Kimb65a is a massive volcaniclastic kimberlite dominated by lithic clasts, magmaclasts, and discrete olivine macrocrysts, hosted within a fine-grained diopside and serpentine-rich matrix. Kimb65b is massive, macrocrystic, coherent kimberlite with a groundmass assemblage of phlogopite, spinel, perovskite, apatite, calcite, serpentine and rare monticellite. Kimb65c is a massive, macrocrystic, hypabyssal kimberlite with a groundmass assemblage of phlogopite, serpentine, calcite, perovskite, spinel, and apatite. Kimb65d is massive volcaniclastic kimberlite with localized textures that are intermediate between volcaniclastic and coherent, with tightly packed magmaclasts separated by a diopside- and serpentine-rich matrix. Lithic clasts of granite-gneiss in kimb65a are weakly reacted, with partial melting of feldspars and crystallization of richterite and actinolite. Lithic clasts in kimb65b and kimb65d are entirely recrystallized to calcite + serpentine/chlorite + pectolite and display inner coronas of diopside-aegirine and an outer corona of phlogopite. Compositions are reported for all minerals in the groundmass of coherent kimberlites, magmaclasts, interclast matrices, and reacted lithic clasts. The Renard 65 rocks are texturally classified as Kimberley-type pyroclastic kimberlites and display transitional textures. The kimberlite units are interpreted to have formed in three melt batches based on their distinct spinel chemistry: kimb65a, kimb65b and kimb65d. We note a strong correlation between the modal abundances of lithic clasts and the textures of the kimberlites, where increasing modal abundances of granite/gneiss are observed in kimberlites with increasingly fragmental textures.

     

Low stable carbon isotope fractionation by coccolithophore RubisCO

The ¹³C/¹²C ratio of carbon compounds is used to identify sources and sinks in the global carbon cycle. However, the relatively enriched ¹³C content observed for marine organic carbon remains enigmatic. The majority of oceanic carbon is fixed by algae and cyanobacteria via the Calvin-Benson-Bassham cycle, yet isotopic discrimination by the CO₂ fixation enzyme, RubisCO (ribulose 1,5-bisphosphate carboxylase/oxygenase), has only been measured for a single marine cyanobacterium. Different forms of RubisCO occur in different phytoplankton species (overall amino acid identity varying by as much as ∼75%) and thus may vary in the degree to which they fractionate carbon. Here we measured isotope discrimination by RubisCO from the coccolithophore Emiliania huxleyi, a cosmopolitan species used as a marine algal model.E. huxleyi RubisCO discriminated substantially less (ε = 11.1‰) against ¹³CO₂ than other RubisCO enzymes (18-29‰), despite having Michaelis-Menten kinetic parameters (K_CO2 = 72 μM; V_max = 0.66 μmol min⁻¹ mg⁻¹ protein) similar to those measured for RubisCO enzymes from different organisms. If widespread, decreased isotope discrimination of ¹³C by phytoplankton RubisCO may be a major factor influencing the enriched ¹³C content of marine organic carbon. This finding emphasizes the necessity of (a) determining ε values for RubisCOs of other marine phytoplankton and (b) re-evaluation of δ¹³C values from physiological, environmental, and geological studies.     

Saturn’s wayward shepherds: the peregrinations of Prometheus and Pandora

Saturn’s narrow F ring is flanked by two nearby small satellites, Prometheus and Pandora, discovered in Voyager images taken in 1980 and 1981 (Synnott et al., 1983, Icarus 53, 156-158). Observations with the Hubble Space Telescope (HST) during the ring plane crossings (RPX) of 1995 led to the unexpected finding that Prometheus was ∼19° behind its predicted orbital longitude, based on the Synnott et al. (1983) Voyager ephemeris (Bosh and Rivkin, 1996 Science 272, 518-521; Nicholson et al., 1996, Science 272, 509-515). Whereas Pandora was at its predicted location in August 1995, McGhee (2000, Ph.D. thesis, Cornell University) found from the May and November 1995 RPX data that Pandora also deviates from the Synnott et al. (1983) Voyager ephemeris. Using archival HST data from 1994, previously unexamined RPX images, and a large series of targeted WFPC2 observations between 1996 and 2002, we have determined highly accurate sky-plane positions for Prometheus, Pandora, and nine other satellites found in our images. We compare the Prometheus and Pandora measurements to the predictions of substantially revised and improved ephemerides for the two satellites based on an extensive analysis of a large set of Voyager images (Murray et al., 2000, Bull. Am. Astron. Soc. 32, 1090; Evans, 2001 Ph.D. thesis, Queen Mary College). From December 1994 to December 2000, Prometheus’ orbital longitude lag was changing by −0.71° year⁻¹ relative to the new Voyager ephemeris. In contrast, Pandora is ahead of the revised Voyager prediction. From 1994 to 2000, its longitude offset changed by +0.44° year⁻¹, showing in addition an ∼585 day oscillatory component with amplitude Δλ_CR0 = 0.65 ± 0.07° whose phase matches the expected perturbation due to the nearby 3:2 corotation resonance with Mimas, modulated by the 71-year libration in the longitude of Mimas due to its 4:2 resonance with Tethys. We determine orbital elements for freely precessing equatorial orbits from fits to the 1994-2000 HST observations, from which we conclude that Prometheus’ semimajor axis was 0.31 km larger, and Pandora’s was 0.20 km smaller, than during the Voyager epoch. Subsequent observations in 2001-2002 reveal a new twist in the meanderings of these satellites: Prometheus’ mean motion changed suddenly by an additional −0.77° year⁻¹, equivalent to a further increase in semimajor axis of 0.33 km, at the same time that Pandora’s mean motion changed by +0.92° year⁻¹, corresponding to a change of −0.42 km in its semimajor axis. There is an apparent anticorrelation of the motions of these two moons seen in the 2001-2002 observations, as well as over the 20-year interval since the Voyager epoch. This suggests a common origin for their wanderings, perhaps through direct exchange of energy between the satellites as the result of resonances, possibly involving the F ring.