Red synchrotron jets in Parkes quasars

We present model fits to spectral energy distributions in the optical and near-infrared of >100 flat-spectrum radio quasars from the Parkes Half-Jansky Flat-spectrum Sample. We find that ∼40 per cent of the sources have power-law spectral energy distributions (SEDs), while a similar number show evidence for two primary components: a blue power law and optical synchrotron emission. The blue power law is similar to the dominant component observed in the spectra of optically selected quasars. There is strong evidence that the synchrotron component has a turnover in the ultraviolet–optical rest frame of the spectrum. In the remaining sources, it is likely that the synchrotron peaks at longer wavelengths. This mixture of two components is supported by optical polarization measurements in a subgroup of the sources. The sources with power-law SEDs show evidence for an excess number of red power-law slopes compared with optically selected quasars. There are additional spectral components in some of the sources, such as dust and the underlying galaxy, which have not been considered here.     

Ediacaran ice-rafting and coeval asteroid impact,South Australia: insights into the terminal Proterozoic environment

Isolated quartzose pebbles, clusters of quartz granules, orthogonal aggregates of poorly sorted quartzose coarse sand, and ovoid pellets (≤2 mm long) of quartz silt occur in hemipelagic marine mudstone of the mid-Ediacaran Bunyeroo Formation exposed in the Adelaide Geosyncline (Adelaide Rift Complex), and ovoid pellets of quartz silt in cores of the correlative marine Dey Dey Mudstone from deep drillholes in the Officer Basin, South Australia. This detritus is interpreted respectively as dropstones, dumps, and frozen aggregates dispersed by sea ice possibly of seasonal origin, and till pellets transported by glacial ice. The ice-rafted material in the Bunyeroo Formation only has been found <10 m stratigraphically below and above a horizon of dacitic ejecta related to the 90 km diameter Acraman impact structure in the Mesoproterozoic Gawler Range Volcanics 300 km to the west. Furthermore, till pellets have been identified 4.4 to 68 m below distal Acraman ejecta in the Dey Dey Mudstone >500 km northwest of the impact site. The Acraman impact took place at a low paleolatitude (～12.5°) and would have adversely affected the global environment. The stratigraphic observations imply, however, that the impact occurred during, but did not trigger, a cold interval marked by sea ice and glacial ice, although the temporal relationship with Ediacaran glaciations elsewhere in Australia and on other continents is unclear. Release from the combined environmental stresses of a frigid, glacial climate near sea-level and a major impact in low latitudes may have been a factor influencing subsequent Ediacaran biotic evolution.     

The Changing Electoral Landscape of the Western United States

The Western periphery constitutes one of the primary electoral sections of the United States in presidential history. The Western periphery, although at times volatile, emerged as a Republican stronghold beginning with Dwight Eisenhower's regional electoral sweeps in the 1950s. This electoral epoch of Republican popularity in the West has been referred to as the new Western normal vote. Despite long-sustained presidential successes, since the 1988 presidential election, Democratic presidential candidates have been able to win certain states in the Republican-dominated region. This research examines the historical dynamics of Republican support in the West by identifying shifts in voting behavior between past and present epochs. We attempt to explain recent changes by exploring the historical character of the West, its demographic dynamics, and the recent turbulence within the Republican Party. County-level election returns from 1952 to 2016 are used, along with traditional and folded T-mode factor analysis, spatial regression modeling, and cartographic analysis. We conclude that the region's normal vote is deteriorating, a new electoral pattern is emerging, and these developments correspond with increasing volatility within the Republican Party.     

Oscillations of the Intertropical Convergence Zone and the genesis of easterly waves Part II: numerical verification

A companion paper (Part I: Toma and Webster 2008), argued that the characteristics of the mean Intertropical Convergence Zone (ITCZ) arise from instabilities associated with the strong cross-equatorial pressure gradient (CEPG) that exists in the eastern Pacific Ocean as a result of the latitudinal sea-surface temperature (SST) gradient. Furthermore, it was argued that instabilities of the mean ITCZ resulted in the in situ development of easterly waves. Thus, in Part I, it was hypothesized that the mean and transient state of eastern Pacific convection was due to local processes and less so to the advection of waves from the North Atlantic Ocean. To test this hypothesis and, at the same time, consider others such as a possible role of the equatorial and subtropical orography in generating local instabilities, a series of controlled numerical experiments are designed using the WRF regional model. The domain of the model was configured to include the western Atlantic Ocean, the Isthmus of Panama and the eastern Pacific Ocean to 155°W. Lateral boundaries were set at 40°N and 40°S, thus containing the mountains of Central America, the Andes and the Sierra Madre of Mexico. In a series of experiments, analysis products were used as boundary conditions that were successively updated four times per day, set as 10-day running average fields or as running mean monthly fields. Finally, the model was run with topography essentially eliminated over the land areas. Although there are differences between the details of the resultant fields, the location of mean convection and the form of the transients remain the same. It is concluded, in support of the theoretical and diagnostic studies of Part I that orographic forcing or waves generated in the North Atlantic Ocean are not the major causes of the mean and transient nature of disturbances in the eastern Pacific.     

Goethite adsorption of Cu(II), Pb(II), Cd(II), and Zn(II) in the presence of sulfate: Properties of the ternary complex

Adsorption of Cu²⁺, Zn²⁺, Cd²⁺, and Pb²⁺ onto goethite is enhanced in the presence of sulfate. This effect, which has also been observed on ferrihydrite, is not predicted by the diffuse layer model (DLM) using adsorption constants derived from single sorbate systems. However, by including ternary surface complexes with the stoichiometry FeOHMSO₄, where FeOH is a surface adsorption site and M²⁺ is a cation, the effect of SO₄²⁻ on cation adsorption was accurately predicted for the range of cation, goethite and SO₄²⁻ concentrations studied. While the DLM does not provide direct molecular scale insights into adsorption reactions there are several properties of ternary complexes that are evident from examining trends in their formation constants. There is a linear relationship between ternary complex formation constants and cation adsorption constants, which is consistent with previous spectroscopic evidence indicating ternary complexes involve cation binding to the oxide surface. Comparing the data from this work to previous studies on ferrihydrite suggests that ternary complex formation on ferrihydrite involves complexes with the same or similar structure as those observed on goethite. In addition, it is evident that ternary complex formation constants are larger where there is a stronger metal-ligand interaction. This is also consistent with spectroscopic studies of goethite-M²⁺-SO₄²⁻ and phthalate systems showing surface species with metal-ligand bonding. Recommended values of ternary complex formation constants for use in SO₄-rich environments, such as acid mine drainage, are presented.     

Paleoshorelines and lowstand sedimentation on subtropical shelves: a case study from the Fraser Shelf,Australia

Evidence of submerged paleoshorelines on tectonically stable continental shelves is represented by relict coastal depositional features that formed during periods of lower sea level. This study investigates two paleoshoreline features that extend 70?km from the Barwon Bank along the southeast Fraser Shelf, off eastern Australia. They are defined by well-lithified, mixed carbonate-siliciclastic deposits now at water depths of 60?m and between 80 and 100?m, located approximately 40?km seaward of the modern shoreline. High-resolution multibeam bathymetry data show geomorphic features that we interpret as paleodunes in the case of the 60?m feature, and paleobarriers in the case of the 80–100?m feature. Sub-bottom profiles also show evidence of prograded beach foresets and paleochannels as components of the Barwon Bank, which is a low and elongate bank that rises about 30?m above the surrounding shelf to a depth of 60?m. Carbonate cements in the rocks forming the paleoshoreline features reveal diagenetic influence of meteoric waters, suggesting that subaerial processes contributed to the formation and preservation of both features. Radiocarbon dating of bioclastic grains (coralline algae, benthic forams) yields an age range between 22.8 and 20.4?ka for the paleobarrier, and an age of 17.3?ka for the paleodune. The morphology of the submerged paleodunes is analogous to modern parabolic dunes on nearby Fraser and Moreton islands. The position and morphology of the paleodunes provide proxy information about the climate history of Australia during the late Quaternary, as these dunes are a likely consequence of the general continent-wide aridity during the Last Glacial Maximum. The preservation of the eolian dunes during marine transgression, despite their direct exposure to coastal hydrodynamic processes, suggests that the dunes were armoured, stabilised and lithified during the glacial lowstand, prior to drowning.     

Geostatistical analysis of arsenic concentration in groundwater in Bangladesh using disjunctive kriging

The National Hydrochemical Survey of Bangladesh sampled the water from 3,534 tube wells for arsenic throughout most of Bangladesh. It showed that 27% of the shallow tube wells (less than 150 m deep) and 1% of the deep tube wells (more than 150 m deep) exceeded the Bangladesh standard for arsenic in drinking water (50 µg L^–1). Statistical analyses revealed the main characteristics of the arsenic distribution. Concentrations ranged from less than the detection limit (0.5 µg L^–1), to as much as 1,600 µg L^–1, though with a very skewed distribution, and with spatial dependence extending to some 180 km. Disjunctive kriging was used to estimate concentrations of arsenic in the shallow ground water and to map the probability that the national limit for arsenic in drinking water was exceeded for most of the country (the Chittagong Hill Tracts and the southern coastal region were excluded). A clear regional pattern was identified, with large probabilities in the south of the country and small probabilities in much of the north including the Pleistocene Tracts. Using these probabilities, it was estimated that approximately 35 million people are exposed to arsenic concentrations in groundwater exceeding 50 µg L^–1 and 57 million people are exposed to concentrations exceeding 10 µg L^–1 (the WHO guideline value).     

Partisan Shifts in Presidential and Gubernatorial Elections in Alabama, 1932–1994*

Although the Republican Party has been competitive in presidential elections in the South for nearly three decades, it has only recently become a force in southern state and local elections. In Alabama, the GOP has dominated presidential voting since 1964, but has only become competitive during the past decade in gubernatorial elections. Why did the GOP first experience success in Alabama in presidential elections 30 years ago, but only recently become competitive in gubernatorial elections? This paper addresses this question using a county-level analysis of both presidential and gubernatorial election returns. It concludes that George Wallace's long political career is the dominant reason for the lag in GOP success in gubernatorial elections.     

Accurate quantification of melt inclusion chemistry by LA-ICPMS: a comparison with EMP and SIMS and advantages and possible limitations of these methods

Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) has recently emerged as a powerful in situ microanalytical technique for major to trace elements in heterogeneous samples such as fluid and melt inclusions. Here, a rigorous comparison of melt inclusion (MI) data acquired by electron microprobe (EMP), ion microprobe (the secondary ion mass spectrometry, SIMS) and LA-ICPMS is used to evaluate the applicability and advantages/drawbacks of these approaches. We are specifically interested in determining if LA-ICPMS data on entire, unexposed, crystallized MI that cannot be homogenized in the lab are accurate and of a useful precision.

Quantification of LA-ICPMS MI signals requires the use of an internal standard, i.e., the concentration of one element, or an element ratio, at the time of MI entrapment must be known independently, in order to derive the pure MI composition from the MI plus host mixed signal. Analysis of plagioclase-hosted glassy MI of a mid-ocean ridge basalt (MORB) sample from the East Pacific Rise illustrates that melt inclusion chemistry can be accurately quantified by LA-ICPMS, including the correction for postentrapment sidewall crystallisation of the host mineral without prior reheating in the lab.

The LA-ICPMS data obtained on crystallized MI demonstrate agreement with the EMP and SIMS data on exposed glassy MI at the 1 standard deviation uncertainty level except for a few elements close to their limits of detection. LA-ICPMS data reduction schemes include the quantification of analytical uncertainty on each element of single MI. Therefore, weighted average element concentrations can be obtained for MI assemblages, at precisions that compare well with those of average element concentrations obtained by EMP and SIMS.

Simple sample preparation minimizing inclusion loss through polishing combined with the analytical efficiency of 50 inclusions plus neighbouring host mineral at up to 40 elements per day enable the collection of statistically relevant datasets by LA-ICPMS. These allow to recognize nonrepresentative MI (e.g., heterogeneous entrapment). Application to individual clinopyroxene crystals from the AD79 pumice horizon of Mt. Somma-Vesuvius reveals chemical variability that exceeds the analytical precision on single melt inclusions. This variability was not obvious from the limited data set obtained by SIMS and EMP.

The largest source of nonquantifiable error for EMP and SIMS data stems from the requirement of reheating the melt inclusions in the lab in order to reverse postentrapment crystallisation onto inclusion walls or growth of crystallites. For LA-ICPMS analysis of unexposed MI, the reliability with which the internal standard (IS) element concentration is known determines the quality of the data. LA-ICPMS, however, cannot analyse H₂O, F, S and Cl reliably, has higher limits of detection (LODs) than SIMS for some elements for MI below 25 μm, has lower spatial resolution than both EMP and SIMS and consumes much more sample per analysis. Therefore, EMP, SIMS and LA-ICPMS are complementary in MI research, and the type of application will determine the analytical method or methods of choice.     

On the pseudo cross-variogram

Normal cross-variograms cannot be estimated from data in the usual way when there are only a few points where both variables have been measured. But the experimental pseudo cross-variogram can be computed even where there are no matching sampling points, and this appears as its principal advantage. The pseudo cross-variogram may be unbounded, though for its existence the intrinsic hypothesis alone is not a sufficient stationarity condition. In addition the differences between the two random processes must be second order stationary. Modeling the function by linear coregionalization reflects the more restrictive stationarity condition: the pseudo cross-variogram can be unbounded only if the unbounded correlation structures are the same in all variograms. As an alternative to using the pseudo cross-variogram a new method is presented that allows estimating the normal cross variogram from data where only one variable has been measured at a point.