ECONOMIC AND FISCAL IMPACTS OF A RETIREMENT/RECREATION COMMUNITY: A STUDY OF TELLICO VILLAGE, TENNESSEE

Retirement/recreation communities (RRCs) have been promoted as a way for some rural regions to develop their economies. RRCs can have substantial economic impacts (changes in employment and income) and fiscal impacts (changes in local government revenues and costs) on rural communities. Because the magnitude and direction of these impacts are site-specific, assessments of RRCs as a rural development strategy should consider both the economic and fiscal impacts for a given region. This paper presents a case study of the economic and fiscal impacts of Tellico Village on Loudon County, Tennessee.Retirement community, Economic and fiscal impacts, Rural development, Community/Rural/Urban Development,

Petrological Constraints on the Recycling of Mafic Crystal Mushes and Intrusion of Braided Sills in the Torres del Paine Mafic Complex (Patagonia)

Cumulate and crystal mush disruption and reactivation are difficult to recognize in coarse-grained, shallow plutonic rocks. Mafic minerals included in hornblende and zoned plagioclase provide snapshots of early crystallization and cumulate formation, but are difficult to interpret in terms of the dynamics of magma ascent and possible links between silicic and mafic rock emplacement. This study presents the field relations, the microtextures and the mineral chemistry of the Miocene mafic sill complex of the Torres del Paine intrusive complex (Patagonia, Chile) and its subvertical feeder zone. We summarize a number of observations that occur in structurally different, shallow, plutonic rocks, as follows. (1) The mafic sill complex was built up by a succession of braided sills of shoshonitic and high-K calc-alkaline porphyritic hornblende-gabbro and fine-grained monzodiorite sills. Local diapiric structures and felsic magma accumulation between sills indicate limited separation of intercumulus liquid from the mafic sills. Anhedral hornblende cores, with olivine + clinopyroxene ± plagioclase ± apatite inclusions, crystallized at temperatures >900°C and pressures of ∼300 to ∼400 MPa. The corresponding rims and monzodiorite matrix crystallized at 950°C) than estimated from the composition of the granite minimum. We show that hornblende-plagioclase thermobarometry is a useful monitor for the determination of the segregation conditions of granitic magmas from gabbroic crystal mushes, and for monitoring the evolution of shallow crustal magmatic crystallization, decompression and coolin

Petrological Constraints on the Recycling of Mafic Crystal Mushes and Intrusion of Braided Sills in the Torres del Paine Mafic Complex (Patagonia)

Cumulate and crystal mush disruption and reactivation are difficult to recognize in coarse-grained, shallow plutonic rocks. Mafic minerals included in hornblende and zoned plagioclase provide snapshots of early crystallization and cumulate formation, but are difficult to interpret in terms of the dynamics of magma ascent and possible links between silicic and mafic rock emplacement. This study presents the field relations, the microtextures and the mineral chemistry of the Miocene mafic sill complex of the Torres del Paine intrusive complex (Patagonia, Chile) and its subvertical feeder zone. We summarize a number of observations that occur in structurally different, shallow, plutonic rocks, as follows. (1) The mafic sill complex was built up by a succession of braided sills of shoshonitic and high-K calc-alkaline porphyritic hornblende-gabbro and fine-grained monzodiorite sills. Local diapiric structures and felsic magma accumulation between sills indicate limited separation of intercumulus liquid from the mafic sills. Anhedral hornblende cores, with olivine + clinopyroxene ± plagioclase ± apatite inclusions, crystallized at temperatures >900°C and pressures of ∼300 to ∼400 MPa. The corresponding rims and monzodiorite matrix crystallized at <830°C, ∼70 MPa. This abrupt compositional variation suggests stability and instability of hornblende during recycling of the mafic roots of the complex and subsequent decompression. (2) The near lack of intercumulus crystals in the subvertical feeder zone layered gabbronorite and pyroxene–hornblende gabbronorite stocks testifies that melt is more efficiently extracted than in sills, resulting in a cumulate signature in the feeding system. Granitic liquids were extracted at a higher temperature (T >950°C) than estimated from the composition of the granite minimum. We show that hornblende–plagioclase thermobarometry is a useful monitor for the determination of the segregation conditions of granitic magmas from gabbroic crystal mushes, and for monitoring the evolution of shallow crustal magmatic crystallization, decompression and cooling

A Detailed Geochemical Study of a Shallow Arc-related Laccolith; the Torres del Paine Mafic Complex (Patagonia)

The shallow crustal Torres del Paine Intrusive Complex in southern Patagonia offers an opportunity to understand the chemical evolution and timing of crystallization processes in shallow plutonic rocks. It is characterized by hornblende-gabbros, gabbronorites, monzodiorites and granitic plutonic rocks. The exceptional exposure of the intrusion permits the identification of two structurally and petrographically different zones. Layered gabbronorite, olivine-bearing pyroxene-hornblende gabbronorite and monzodiorite forming vertical sheets and stocks in the west are referred to here as the feeder zone. These mafic rocks are in vertical contact with younger granitic rocks on their eastern border. The eastern part is a laccolith complex. It is characterized by three major units (I, II, III) of granitic rocks of over 1000 m vertical thickness; these are underlain in places by a sequence of hornblende-gabbro sills intermingled with evolved monzodiorite granite. Chilled, crenulated margins as well as flame structures between gabbroic rocks and monzodiorites suggest that the mafic sill complex remained partially molten during most of its construction. Bulk-rock major and trace element data indicate that the Paine mafic rocks follow a high-K calc-alkaline to shoshonitic differentiation trend. The parental magmas were basaltic trachyandesite liquids, with variable H2O and alkali contents. The majority of the feeder zone gabbronorites have high Al2O3 contents and positive Eu and Sr anomalies, consistent with accumulation of plagioclase and efficient extraction of intercumulus melt. The mafic sill complex largely lacks these cumulate signatures. Comparisons of the intercumulus groundmass in the hornblende-gabbros with intra-sill dioritic stocks and pods reveal similar rare earth element patterns and trace element ratios indicating incomplete extraction of evolved interstitial liquids. The Sr, Nd and Pb isotopic compositions of the mafic and granitic rocks exhibit ranges of 87Sr/86Sr of 0·704-0·708, εNd +3·8 to −1·2, 206Pb/204Pb 18·61-18·77, 207Pb/204Pb 15·67-15·67 and 208Pb/204Pb 38·56-38·77. Crystal fractionation and assimilation-fractional crystallization modelling, combined with high-precision U-Pb dating of zircons, indicates that the western feeder zone gabbronorites are linked to the uppermost Paine granite (granite I), whereas the mafic sill complex is younger and not directly related to the voluminous granite units II and III. These results are interpreted to indicate that crystal-liquid separation is facilitated in subvertical, dynamic feeder systems whereas subhorizontal sill complexes are inefficient in separating large volumes of mafic cumulates and complementary felsic rock

Overbias Light Emission From Memristive Nanojunctions

A nanoscale dielectric gap clamped between two metal electrodes may undergo a large resistance change from insulating to highly conducting upon applying an electrical stress. This sudden resistive switching effect is largely exploited in memristors for emulating synapses in neuromorphic neural networks. Here, we show that resistive switching can be accompanied by a release of electromagnetic radiation spanning the visible spectral region. Importantly, we find that the spectrum is characterized by photon energies exceeding the maximum kinetic energy of electrons provided by the switching voltage. This so-called overbias emission can be described self-consistently by a thermal radiation model featuring an out-of-equilibrium electron distribution generated in the device with an effective temperature exceeding 2000~K. The emitted spectrum is understood in terms of hot electrons radiatively decaying to resonant optical modes occurring in a nanoscale \ch{SiO2} matrix located between two \ch{Ag} electrodes. The correlation between resistive switching and the onset of overbias emission in atomic-scale photonic memristor brings new venues to generate light on chip and their exploitation in optical interconnects. Photons emitted during memristive switching can also be monitored to follow the neural activation pathways in memristor-based networks

Optical interconnect with densely integrated plasmonic modulator and germanium photodetector arrays

We demonstrate the first chip-to-chip interconnect utilizing a densely integrated plasmonic Mach-Zehnder modulator array operating at 3 x 10 Gbit/s. A multicore fiber provides a compact optical interface, while the receiver consists of germanium photodetectors

Optical interconnect solution with plasmonic modulator and Ge photodetector array

We report on an optical chip-to-chip interconnect solution, thereby demonstrating plasmonics as a solution for ultra-dense, high-speed short-reach communications. The interconnect comprises a densely integrated plasmonic Mach-Zehnder modulator array that is packaged with standard driving electronics. On the receiver side, a germanium photodetector array is integrated with trans-impedance amplifiers. A multicore fiber provides a compact optical interface to the array. We demonstrate 4 × 20 Gb/s on-off keying signaling with direct detection.ISSN:1041-1135ISSN:1941-017

Shifts in controls and abundance of particulate and mineral-associated organic matter fractions among subfield yield stability zones

Spatiotemporal yield heterogeneity presents a significant challenge to agricultural sustainability efforts and can strain the economic viability of farming operations. Increasing soil organic matter (SOM) has been associated with increased crop productivity, as well as the mitigation of yield variability across time and space. Observations at the regional scale have indicated decreases in yield variability with increasing SOM. However, the mechanisms by which this variability is reduced remain poorly understood, especially at the farm scale. To better understand the relationship between SOM and yield heterogeneity, we examined its distribution between particulate organic matter (POM) and mineral-associated organic matter (MAOM) at the subfield scale within nine farms located in the central United States. We expected that the highest SOM concentrations would be found in stable, high-yielding zones and that the SOM pool in these areas would have a higher proportion of POM relative to other areas in the field. In contrast to our predictions, we found that unstable yield areas had significantly higher SOM than stable yield areas and that there was no significant difference in the relative contribution of POM to total SOM across different yield stability zones. Our results further indicate that MAOM abundance was primarily explained by interactions between crop productivity and edaphic properties such as texture, which varied amongst stability zones. However, we were unable to link POM abundance to soil properties or cropping system characteristics. Instead, we posit that POM dynamics in these systems may be controlled by differences in decomposition patterns between stable and unstable yield zones. Our results show that, at the subfield scale, increasing SOM may not directly confer increased yield stability. Instead, in fields with high spatiotemporal yield heterogeneity, SOM stocks may be determined by interactive effects of topography, weather, and soil characteristics on crop productivity and SOM decomposition. These findings suggest that POM has the potential to be a useful indicator of yield stability, with higher POM stocks in unstable zones, and highlights the need to consider these factors during soil sampling campaigns, especially when attempting to quantify farm-scale soil C stocks.</p

Successive episodes of reactive liquid flow through a layered intrusion (Unit 9, Rum Eastern Layered Intrusion, Scotland)

We present a detailed microstructural and geochemical study of reactive liquid flow in Unit 9 of the Rum Eastern Layered Intrusion, Scotland. Unit 9 comprises an underlying lens-like body of peridotite overlain by a sequence of troctolite and gabbro (termed allivalite), with some local and minor anorthosite. The troctolite is separated from the overlying gabbro by a distinct, sub-horizontal, undulose horizon (the ‘major wavy horizon’). Higher in the stratigraphy is another, similar, horizon (the ‘minor wavy horizon’) that separates relatively clinopyroxene-poor gabbro from an overlying gabbro. To the north of the peridotite lens, both troctolite and gabbro grade into poikilitic gabbro. Clinopyroxene habit in the allivalite varies from thin rims around olivine in troctolite to equigranular crystals in gabbro and to oikocrysts in poikilitic gabbro. The poikilitic gabbros contain multiple generations of clinopyroxene, with Cr-rich (~1.1 wt% Cr2O3) anhedral cores with moderate REE concentrations (core1) overgrown by an anhedral REE-depleted second generation with moderate Cr (~0.7 wt% Cr2O3) (core2). These composite cores are rimmed by Cr-poor (~0.2 wt% Cr2O3) and REE-poor to -moderate clinopyroxene. We interpret these microstructures as a consequence of two separate episodes of partial melting triggered by the intrusion of hot olivine-phyric picrite to form the discontinuous lenses that comprise the Unit 9 peridotite. Loss of clinopyroxene-saturated partial melt from the lower part of the allivalite immediately following the early stages of sill intrusion resulted in the formation of clinopyroxene-poor gabbro. The spatial extent of clinopyroxene loss is marked by the minor wavy horizon. A second partial melting event stripped out almost all clinopyroxene from the lowest allivalite to form a troctolite, with the major wavy horizon marking the extent of melting during this episode. The poikilitic gabbro formed from clinopyroxene-saturated melt moving upwards and laterally through the remobilized cumulate pile and precipitating clinopyroxene en route. This process, called reactive liquid flow, is potentially important in open magma chambers