AN ANALYSIS OF RATES OF CHANGE IN COMMUNITY PER CAPITA INCOME BY DISCRIMINANT ANALYSIS

Research Methods/ Statistical Methods,

TRANSPORTATION ALTERNATIVES IN RURAL COMMUNITIES: A FEASIBILITY ANALYSIS

Public Economics,

Late quaternary time series of Arabian Sea productivity: Global and regional signals

Modern annual floral and faunal production in the northwest Arabian Sea derives primarily from upwelling induced by strong southwest winds during June, July, and August. Indian Ocean summer monsoon winds are, in turn, driven by differential heating between the Asian continent and the Indian ocean to the south. This differential heating produces a strong pressure gradient resulting in southwest monsoon winds and both coastal and divergent upwelling off the Arabian Peninsula. Over geologic time scales (10(exp 4) to 10(exp 6) years), monsoon wind strength is sensitive to changes in boundary conditions which influence this pressure gradient. Important boundary conditions include the seasonal distribution of solar radiation, global ice volume, Indian Ocean sea surface temperature, and the elevation and albedo of the Asian continent. To the extent that these factors influence monsoon wind strength, they also influence upwelling and productivity. In addition, however, productivity associated with upwelling can be decoupled from the strength of the summer monsoon winds via ocean mechanisms which serve to inhibit or enhance the nutrient supply in the intermediate waters of the Indian Ocean, the source for upwelled waters in the Arabian Sea. To differentiate productivity associated with wind-induced upwelling from that associated with other components of the system such as nutrient sequestering in glacial-age deep waters, we employ a strategy which monitors independent components of the oceanic and atmospheric subsystems. Using sediment records from the Owen Ridge, northwest Arabian Sea, we monitor the strength of upwelling and productivity using two independent indicators, percent G. bulloides and opal accumulation. We monitor the strength of southwest monsoon winds by measuring the grain-size of lithogenic dust particles blown into the Arabian Sea from the surrounding deserts of the Somali and Arabian Peninsulas. Our current hypothesis is that the variability associated with the 41 kyr power in the G. bulloides and opal accumulation records derive from nutrient availability in the intermediate waters which are upwelled via monsoon winds. This hypothesis is testable by comparison with Cd records of intermediate and deep waters of the Atlantic and Indian Ocean

Determination of in situ dissolved inorganic carbon concentration and alkalinity for marine sedimentary porewater

Dissolved inorganic carbon (DIC) concentration and total alkalinity in marine sediment vary with biological activity, mineral diagenesis and past bottom ocean water composition. Reliable interpretation of this data is often compromised due to precipitation of calcium carbonate (CaCO3) during sediment recovery, processing and sample storage. Here we present and test a method that corrects for this precipitation and consequently allows quantification of in situ carbonate system chemistry. Our method relies on the over-determination of the dissolved carbonate system by (i) measuring DIC, alkalinity and calcium, and (ii) explicitly assuming CaCO3 saturation in the sediment. We experimentally tested this method using data from Integrated Ocean Drilling Program (IODP) Site U1368 in the South Pacific Gyre. Our results show that we can accurately reproduce in situ aqueous carbonate system chemistry if DIC, alkalinity and calcium concentration are measured simultaneously. At Site U1368, the correction for sampling associated precipitation is equivalent to 4.5 and 8.9% of the measured DIC and alkalinity, respectively. The method is well suited for any sediment porewater that is saturated with respect to calcium carbonate; consequently, it is applicable for approximately 50% of the global oceanic seafloor

Sensitivity of Prescribing High-Intensity, Interval Training Using the Critical Power Concept

International Journal of Exercise Science 8(3): 202-212, 2015. The critical power (CP) concept enables the calculation of time to exhaustion (tLIM) for a given power output above CP using the equation of tLIM = W’/(power – CP), where W’ is the curvature constant, and CP is the asymptote for the power-tLIM relationship. The CP concept offers great promise for prescribing high-intensity interval training (HIIT); however, knowledge on the concept’s sensitivity is lacking (i.e., how much of a difference in W’ expenditure is needed to evoke different metabolic responses). We tested if two different power-tLIM configurations expending identical proportions of W’ would evoke different end-exercise oxygen uptake (VO2) and heart rate (HR) values. Five men and five women completed a graded exercise test, 3-min all-out exercise tests, and intervals prescribed to deplete either 70 or 80% of W’ on separate visits. Consistency statistics of intraclass correlation (ICC a), standard error of measure (SEM), and coefficient of variation (CV) were calculated on end-exercise values. End-exercise VO2 were similar for the 3.5- and 5-min bouts, depleting 70% of W’ (ICC a = 0.91, SEM = 3.23 mL·kg-1·min-1, CV = 8.1%) and similar for the 4- and 5-min bouts, depleting 80% of W’ (ICC a = 0.95, SEM = 2.34 mL·kg-1·min-1, CV = 8.1%). No VO2 differences were observed between trials or conditions (p = 0.58). Similarly, HR values (~181 b·min-1) did not differ between trials or conditions (p = 0.45). Use of the CP concept for HIIT prescriptions of different power-tLIM configurations evokes similar end-exercise VO2 values on a given day. Our findings indicate that \u3e10% W’ depletion is necessary to evoke different metabolic responses to HIIT

Deep North Atlantic last glacial maximum salinity reconstruction

Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography and Paleoclimatology 36(7), (2021): e2020PA004088, https://doi.org/10.1029/2020PA004088.We reconstruct deep water-mass salinities and spatial distributions in the western North Atlantic during the Last Glacial Maximum (LGM, 19–26 ka), a period when atmospheric CO2 was significantly lower than it is today. A reversal in the LGM Atlantic meridional bottom water salinity gradient has been hypothesized for several LGM water-mass reconstructions. Such a reversal has the potential to influence climate, ocean circulation, and atmospheric CO2 by increasing the thermal energy and carbon storage capacity of the deep ocean. To test this hypothesis, we reconstructed LGM bottom water salinity based on sedimentary porewater chloride profiles in a north-south transect of piston cores collected from the deep western North Atlantic. LGM bottom water salinity in the deep western North Atlantic determined by the density-based method is 3.41–3.99 ± 0.15% higher than modern values at these sites. This increase is consistent with: (a) the 3.6% global average salinity change expected from eustatic sea level rise, (b) a northward expansion of southern sourced deep water, (c) shoaling of northern sourced deep water, and (d) a reversal of the Atlantic's north-south deep water salinity gradient during the LGM.This work was supported by the US National Science Foundation (grant numbers 1433150 and 1537485).2021-10-2

Radiolytic Hydrogen Production in the Subseafloor Basaltic Aquifer

Hydrogen (H2) is produced in geological settings by dissociation of water due to radiation from radioactive decay of naturally occurring uranium (238U, 235U), thorium (232Th) and potassium (40K). To quantify the potential significance of radiolytic H2 as an electron donor for microbes within the South Pacific subseafloor basaltic aquifer, we use radionuclide concentrations of 43 basalt samples from IODP Expedition 329 to calculate radiolytic H2 production rates in basement fractures. The samples are from three sites with very different basement ages and a wide range of alteration types. U, Th, and K concentrations vary by up to an order of magnitude from sample to sample at each site. Comparison of our samples to each other and to the results of previous studies of unaltered East Pacific Rise basalt suggests that significant variations in radionuclide concentrations are due to differences in initial (unaltered basalt) concentrations (which can vary between eruptive events) and post-emplacement alteration. However, there is no clear relationship between alteration type and calculated radiolytic yields. Local maxima in U, Th, and K produce hotspots of H2production, causing calculated radiolytic rates to differ by up to a factor of 80 from sample to sample. Fracture width also greatly influences H2 production, where microfractures are hotspots for radiolytic H2 production. For example, H2 production rates normalized to water volume are 190 times higher in 1 μm wide fractures than in fractures that are 10 cm wide. To assess the importance of water radiolysis for microbial communities in subseafloor basaltic aquifers, we compare electron transfer rates from radiolysis to rates from iron oxidation in subseafloor basalt. Radiolysis appears likely to be a more important electron donor source than iron oxidation in old (\u3e10 Ma) basement basalt. Radiolytic H2 production in the volume of water adjacent to a square cm of the most radioactive SPG basalt may support as many as 1500 cells

Dust, Volcanic Ash, and the Evolution of the South Pacific Gyre through the Cenozoic

We examine the 0–100 Ma paleoceanographic record retained in pelagic clay from the South Pacific Gyre (SPG) by analyzing 47 major, trace, and rare earth elements in bulk sediment in 206 samples from seven sites drilled during Integrated Ocean Drilling Program Expedition 329. We use multivariate statistical analyses (Q-mode factor analysis and multiple linear regression) of the geochemical data to construct a model of bulk pelagic clay composition and mass accumulation rates (MAR) of six end-members, (post-Archean average Australian shale, rhyolite, basalt, Fe-Mn-oxyhydroxides, apatite, and excess Si). Integrating the results with Co-based age models at Sites U1365, U1366, U1369, and U1370, we link changes in MAR of these components to global oceanographic, terrestrial, and climatic transformations through the Cenozoic. Our results track the spatial extent (thousands of kilometers) of dust deposition in the SPG during the aridification of Australia. Dispersed ash is a significant component of the pelagic clay, often comprising \u3e50% by mass, and records episodes of Southern Hemisphere volcanism. Because both are transported by wind, the correlation of dust and ash MAR depends on the site\u27s latitude and suggests meridional shifts in the position of atmospheric circulation cells. The hydrothermal MARs provide evidence for rapid deposition from the Osbourn Trough spreading ridge before it went extinct. Excess Si MARs show that the abrupt increase in siliceous productivity observed at Site U1371 also extended at least as far north as Sites U1369 and U1370, suggesting large-scale reorganizations of oceanic Si distributions ~10–8 Ma in the southern SPG

Spatting restricts ankle motion more effectively than taping during exercise

Ankle injuries, via plantarflexion (PF) and inversion, are commonplace today. To reduce ankle injuries, restrictive appliances such as taping and bracing have been employed. These appliances, however, have the disadvantage of potentially loosening considerably with mild activity. Spatting—applying tape over the shoe and sock—has been suggested as a viable alternative, yet its efficacy has not been researched widely. We examined the effects of taping or spatting the ankles on 17 men (age = 20.7 ± 2.1 years; height = 185.7 ± 5.7 cm; mass = 93.6 ± 16.2 kg) before, during, and after 60 minutes of exercise involving multi-directional activity. Active range of motion (ROM) for PF and inversion was measured via goniometry for each subject\u27s dominant leg to establish baseline values. ROM was measured after the appliances were applied, then following a five-minute warm-up period, and after each of three, 20-minute exercise periods. The subjects also completed a 5-item, 5-point Likert-type scale survey regarding their perceptions of each ankle appliance with respect to comfort, effectiveness, and protective ability. Separate, two-way ANOVAs with repeated measures were used to assess differences in PF and inversion ROM relative to time. A series of Wilcoxon tests were used to assess the Likert-type scale survey. In comparison to spatting, taping loosened by ~5° for PF at 40 minutes and by ~3° for inversion at 20 minutes (both significant interactions, p \u3c 0.01). Thus indicating that spatting is more restrictive than taping after 20 minutes of exercise. Interestingly, taping was perceived as more comfortable than spatting (Z = 2.03, p = 0.04); nonetheless, the perceived protection along with the perceived ability to move before, during, and after exercise was rated similarly between the appliances (p \u3e 0.05). Despite an advantage of restricting PF and inversion during exercise with spatting, it is not known if the loss of tape-skin contact underscores the potential benefits associated with the neuromuscular reactivity that have been reported with taping. Additional research is needed to clarify this issue