ALBERT

Description: The Aeolis and Zephyria Plana contain the western-most portion of the Medusae Fossae Formation (MFF), an enigmatic and extensive light-toned deposit located in the Martian equatorial region and dated from the Hesperian to Amazonian epochs. This area hosts a large population of sinuous ridges (SRs), interpreted as inverted fluvial features, formed by precipitation, indurated by chemical cementation, buried by subsequent deposition, and finally exhumed. This interpretation of SRs as uniformly fluvial represents a modification to an earlier hypothesis for one particular SR of possible glaciofluvial (i.e. esker) formation. These SRs provide a tool to investigate the degree and character of post-fluvial modification processes in this region. We combined digital terrain models made from Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) stereo image pairs with individual data points from the Mars Orbiter Laser Altimeter (MOLA) to estimate relief, cross-sectional profiles, longitudinal profiles and slope directions of selected SRs. Longitudinal profiles of several SRs display undulations with amplitudes of up to order 100 m. While some of the lower amplitude undulations may be due to differential erosion, undulations having amplitudes in excess of SR relief require alternative explanations. Our combined morphologic and topographic analysis suggests that multiple post-flow processes, including compaction of the deposits and tectonic displacements, have modified the original SR profiles. Specification of the type(s) and magnitudes of these modification processes will contribute to understanding both the potential of post-flow modification of fluvial profiles elsewhere on Mars as well as the nature and properties of the MFF.

Description: Although aeolian landforms are pervasive on Mars, evidence for contemporary activity has been limited. The next major campaign for the Mars Exploration Rover “Opportunity” is the investigation of the ∼20 km diameter Endeavor crater, ∼6 km to southeast of the rover's position as of December 2010. We present evidence from orbital imagery that eight aeolian bed forms (∼14,000 m2) in Endeavor crater have been active within the past decade (2001–2009), at a spatial scale that should be directly observable by Opportunity from the crater rim. Two dunes appear to show translational migration (∼10–20 m), but all dunes indicate erosion to be the dominant process with up to 100% sediment removal. Thermophysical properties of these dunes are consistent with very fine to fine sand sizes, the particle sizes most easily moved by the Martian atmosphere. The dunes that show the most surface change have a rippled appearance without well-defined slip faces. Based on their morphology (elliptical shape), we classify them as dome dunes. Mesoscale atmospheric modeling is employed to provide insight into the atmospheric forcing of this aeolian system. The major wind regimes from modeling are consistent with observations of wind streaks, sand streamers, ripples, and slip faces of regional dune fields although modeled wind speeds are insufficient to move sand. The translation and erosion of these dunes constitutes the largest contemporary movement of sand-sized sediment reported on Mars to date and demonstrates that Endeavor crater has been subject to wind profiles exceeding the threshold velocity at the surface (daily/seasonally and/or episodically) in the recent past.

Description: Abstract Central pit craters (CPCs) are complex craters that exhibit depressions within their floors or central uplifts. Some proposed models for central pit formation can be grouped by similar mechanism: (A) explosive volatile release, (B) central peak collapse, and (C) drainage of subsurface melted volatiles. We test these groups of mechanisms for central pit formation on Mars based on morphometries expected from each mechanism. Volatiles in the target (A and C) would be expected to result in a correlation with layered ejecta, also formed from volatiles, for CPCs over non‐CPCs. Central peak collapse (B) should result in larger diameters for pit rims than central peaks due to outward flow. Explosive volatile release (A) should yield smaller volumes for pit rims than pits due to mass loss. Data were collected on Context Camera images and digital elevation models for random samples of CPCs to assess the presence of these expected morphologies. Results of a Fisher exact test showed no preference in layered ejecta with CPCs over non‐CPCs, inconsistent with volatiles in the target. Results of an independent t test showed that central pit rim diameters are larger than central peak diameters, supporting some component of central peak collapse, although measurement uncertainty makes this interpretation tentative. Central pit rim volumes were not found to be statistically smaller than their pits, weighing against formation by explosive volatile release. Thus, our findings do not support any single group of formation mechanism tested here, although they allow for formation by some combination of these (or other) processes.

Description: IJERPH, Vol. 15, Pages 2029: The Oakville Oil Refinery Closure and Its Influence on Local Hospitalizations: A Natural Experiment on Sulfur Dioxide International Journal of Environmental Research and Public Health doi: 10.3390/ijerph15092029 Authors: Wesley S. Burr Robert Dales Ling Liu Dave Stieb Marc Smith-Doiron Branka Jovic Lisa Marie Kauri Hwashin Hyun Shin Background: An oil refinery in Oakville, Canada, closed over 2004–2005, providing an opportunity for a natural experiment to examine the effects on oil refinery-related air pollution and residents’ health. Methods: Environmental and health data were collected for the 16 years around the refinery closure. Toronto (2.5 million persons) and the Greater Toronto Area (GTA, 6.3 million persons) were used as control and reference populations, respectively, for Oakville (160,000 persons). We compared sulfur dioxide and age- and season-standardized hospitalizations, considering potential factors such as changes in demographics, socio-economics, drug prescriptions, and environmental variables. Results: The closure of the refinery eliminated 6000 tons/year of SO2 emissions, with an observed reduction of 20% in wind direction-adjusted ambient concentrations in Oakville. After accounting for trends, a decrease in cold-season peak-centered respiratory hospitalizations was observed for Oakville (reduction of 2.2 cases/1000 persons per year, p = 0.0006 ) but not in Toronto (p = 0.856) and the GTA (p = 0.334). The reduction of respiratory hospitalizations in Oakville post closure appeared to have no observed link to known confounders or effect modifiers. Conclusion: The refinery closure allowed an assessment of the change in community health. This natural experiment provides evidence that a reduction in emissions was associated with improvements in population health. This study design addresses the impact of a removed source of air pollution.

Description: IJERPH, Vol. 15, Pages 1566: Air Health Trend Indicator: Association between Short-Term Exposure to Ground Ozone and Circulatory Hospitalizations in Canada for 17 Years, 1996–2012 International Journal of Environmental Research and Public Health doi: 10.3390/ijerph15081566 Authors: Hwashin Hyun Shin Wesley S. Burr Dave Stieb Lani Haque Harun Kalayci Branka Jovic Marc Smith-Doiron The Air Health Trend Indicator is designed to estimate the public health risk related to short-term exposure to air pollution and to detect trends in the annual health risks. Daily ozone, circulatory hospitalizations and weather data for 24 cities (about 54% of Canadians) for 17 years (1996–2012) were used. This study examined three circulatory causes: ischemic heart disease (IHD, 40% of cases), other heart disease (OHD, 31%) and cerebrovascular disease (CEV, 14%). A Bayesian hierarchical model using a 7-year estimator was employed to find trends in the annual national associations by season, lag of effect, sex and age group (≤65 vs. >65). Warm season 1-day lagged ozone returned higher national risk per 10 ppb: 0.4% (95% credible interval, −0.3–1.1%) for IHD, 0.4% (−0.2–1.0%) for OHD, and 0.2% (−0.8–1.2%) for CEV. Overall mixed trends in annual associations were observed for IHD and CEV, but a decreasing trend for OHD. While little age effect was identified, some sex-specific difference was detected, with males seemingly more vulnerable to ozone for CEV, although this finding needs further investigation. The study findings could reduce a knowledge gap by identifying trends in risk over time as well as sub-populations susceptible to ozone by age and sex.

Description: Drainage networks on Titan, Earth, and Mars provide the only known examples of non-volcanic fluvial activity in our solar system. The drainage networks on Titan are apparently the result of a methane-ethane cycle similar to Earth's water cycle. The scarcity of impact craters and the uneven distribution of fluvial dissection on Titan suggest that the surface may be relatively young. The purpose of this study is to assess the importance of erosion relative to other plausible mechanisms of resurfacing such as tectonic deformation, cryovolcanism, or deposition of aerosols. We present a new method, based on a measure of drainage network shape known as the width function, to estimate cumulative erosion into an initially rough surface. We calibrate this method with a numerical landscape evolution model, and successfully test the method by applying it to river networks on Earth with different exhumation histories. To estimate erosional exhumation on Titan, we mapped fluvial networks in all Synthetic Aperture Radar swaths obtained by the Cassini spacecraft through T71. Application of our method to the most completely imaged drainage networks indicates that for two of four regions analyzed, Titan's fluvial networks have produced only minor erosional modification of the surface. For the best-constrained region in the northern high latitudes, we find that fluvial networks reflect spatially averaged erosion of more than 0.4% but less than 9% of the initial topographic relief. This result implies either a recent, non-fluvial resurfacing event or long-term fluvial incision rates that are slow relative to the rate of resurfacing.

Description: Fault dips are a function of the coefficient of internal friction, μ i , of the lithospheric material. Laboratory deformation experiments of H 2 O ice at conditions applicable to icy bodies yield 0 ≤ μ i ≤ 0.55 such that normal faults dip between 45° and 59°. We tested the hypothesis that normal faults on icy bodies reflect these values by using digital elevation models to examine geometries of large extensional systems on three Saturnian satellites. Analyzed faults within Ithaca Chasma on Tethys and Avaiki Chasmata on Rhea all exhibit shallower-than-predicted topographic slopes across the fault scarp, which we term ‘fault slopes’. A scarp of Padua Chasmata within Dione's Wispy Terrain also has a shallow fault slope, although three others that make up Palatine Chasmata exhibit steeper slopes as predicted. We infer that viscous relaxation is the most viable explanation for these shallow fault slopes, and we model the potential role of viscous relaxation in creating shallow fault slopes. Our modeling results support formation of these normal faults with steep dips consistent with deformation experiments, followed by their relaxation due to lithospheric heating events related to radionuclide decay. The steepest fault slopes in this terrain yield 0 ≤ μ i ≤ 0.73 for Dione's lithospheric ice, which overlaps the dip range predicted from experiments. Results of this work suggest that viscous relaxation substantially affected fault slopes on Tethys, Rhea, and Dione. By implication, these processes may have also affected fault geometries on other icy satellites.

Description: This study presents the Swedish standard version of the Copenhagen Psychosocial Questionnaire, COPSOQ III, and investigates its reliability and validity at individual and workplace levels with the aim of establishing benchmarks for the psychosocial work environment. Cross-sectional data from (1) a random sample of employees in Sweden aged 25–65 years (N = 2847) and (2) a convenience sample of non-managerial employees at 51 workplaces (N = 1818) were analysed. Internal consistency reliability was evaluated as well as the effects of sex, work sector and blue/white-collar work. Population benchmarks and mean scores for major occupational groups were computed based on weighted data. ICC(1) and ICC(2) estimates were computed to evaluate aggregation to the workplace level and Pearson inter-correlations to evaluate construct validity at individual and aggregated levels. The reliability and scale characteristics were satisfactory, with few exceptions, at both individual and workplace levels. The strength and direction of correlations supported the construct validity of the dimensions and the amount of variance explained by workplace justified aggregation to the workplace level. The present study thus supports the use of COPSOQ III for measurement at the workplace level and presents benchmarks for risk management as well as for research purposes.

Description: Background: An oil refinery in Oakville, Canada, closed over 2004–2005, providing an opportunity for a natural experiment to examine the effects on oil refinery-related air pollution and residents’ health. Methods: Environmental and health data were collected for the 16 years around the refinery closure. Toronto (2.5 million persons) and the Greater Toronto Area (GTA, 6.3 million persons) were used as control and reference populations, respectively, for Oakville (160,000 persons). We compared sulfur dioxide and age- and season-standardized hospitalizations, considering potential factors such as changes in demographics, socio-economics, drug prescriptions, and environmental variables. Results: The closure of the refinery eliminated 6000 tons/year of SO2 emissions, with an observed reduction of 20% in wind direction-adjusted ambient concentrations in Oakville. After accounting for trends, a decrease in cold-season peak-centered respiratory hospitalizations was observed for Oakville (reduction of 2.2 cases/1000 persons per year, p = 0.0006 ) but not in Toronto (p = 0.856) and the GTA (p = 0.334). The reduction of respiratory hospitalizations in Oakville post closure appeared to have no observed link to known confounders or effect modifiers. Conclusion: The refinery closure allowed an assessment of the change in community health. This natural experiment provides evidence that a reduction in emissions was associated with improvements in population health. This study design addresses the impact of a removed source of air pollution.