Sympatric seagrass shrimp show similar structure and selection along the seashore: a comparison of two cryptic Phycomenes zostericola lineages

Small crustaceans are diverse and abundant in seagrass habitats and provide many ecological services. Further information is needed about their long‐ and short‐term response to habitat fragmentation and loss. Shrimp specimens were sampled from coastal seagrasses: latitudes 9°–27° S (Torres Strait to Moreton Bay, Queensland, Australia) and longitudes 141°–153° E (Weipa to Moreton Bay, Queensland, Australia). The seagrass shrimp Phycomenes zostericola (Caridea: Decapoda) underwent phylogeographic analysis using mitochondrial and nuclear sequence data. Lineage relationships were investigated and two deeply divergent sympatric lineages of P. zostericola were discovered in northern samples. The two lineages display vastly different demographic histories in spite of similar overall phylogeographic patterns. The two lineages appear to be in secondary contact with each other, detailing independent histories of sea level change, long distance colonisation and habitat fragmentation. Their regional structure is evidence that the potential for dispersal is only realised under specific environmental conditions. Nuclear data, used to determine reproductive status between lineages, instead displayed a non‐random latitudinal geographic distribution suggesting directional selection, possibly in response to ocean temperatures. The differences between the two deeply divergent lineages highlight the importance of understanding variability among cryptic taxa and their response to habitat change.     

Complex erosional response to uplift and rock strength contrasts in transient river systems crossing an active normal fault revealed by 10Be and 26Al cosmogenic nuclide analyses

Understanding the influence of bedrock lithology on the catchment-averaged erosion rates of normal fault-bounded catchments and the effect that different bedrock erodibilties have on the evolution of transient fluvial geomorphology remain major challenges. To investigate this problem, we collected 18 samples for ¹⁰Be and ²⁶Al cosmogenic nuclide analysis to determine catchment-averaged erosion rates along the well-constrained Gediz Fault system in western Türkiye, which is experiencing fault-driven river incision owing to a linkage event ~0.8 Ma and has weak rocks overlying strong rocks in the footwall. Combined with existing cosmogenic data, we show that the background rate of erosion of the pre-incision landscape can be constrained as <92 mMyr⁻¹, and erosion rates within the transient reach vary from 16 to 1330 mMyr⁻¹. Erosion rates weakly scale with unit stream power, steepness index and slip rate on the bounding fault, although erosion rates are an order of magnitude lower than slip rates. However, there are no clear relationships between erosion rate and relief or catchment slope. Bedrock strength is assessed using Schmidt hammer rebound and Selby Rock Mass Strength Assessments; despite a 30-fold difference in erodibility, there is no difference in the erosion rate between strong and weak rocks. We argue that, for the Gediz Graben, the strong lithological contrast affects the ability of the river to erode the bed, resulting in a complex erosional response to uplift along the graben boundary fault. Weak covariant trends between erosion rates and various topographic factors potentially result from incomplete sediment mixing or pre-existing topographic inheritance. These findings indicate that the erosional response to uplift along an active normal fault is a complex response to multiple drivers that vary spatially and temporally.     

Radio source calibration for the Very Small Array and other cosmic microwave background instruments at around 30 GHz

Accurate calibration of data is essential for the current generation of cosmic microwave background (CMB) experiments. Using data from the Very Small Array (VSA), we describe procedures which will lead to an accuracy of 1 per cent or better for experiments such as the VSA and CBI. Particular attention is paid to the stability of the receiver systems, the quality of the site and frequent observations of reference sources. At 30 GHz the careful correction for atmospheric emission and absorption is shown to be essential for achieving 1 per cent precision.
The sources for which a 1 per cent relative flux density calibration was achieved included Cas A, Cyg A, Tau A and NGC 7027 and the planets Venus, Jupiter and Saturn. A flux density, or brightness temperature in the case of the planets, was derived at 33 GHz relative to Jupiter which was adopted as the fundamental calibrator. A spectral index at ∼30 GHz is given for each.
Cas A, Tau A, NGC 7027 and Venus were examined for variability. Cas A was found to be decreasing at 0.394 ± 0.019 per cent yr⁻¹ over the period 2001 March to 2004 August. In the same period Tau A was decreasing at 0.22 ± 0.07 per cent yr⁻¹. A survey of the published data showed that the planetary nebula NGC 7027 decreased at 0.16 ± 0.04 per cent yr⁻¹ over the period 1967–2003. Venus showed an insignificant (1.5 ± 1.3 per cent) variation with Venusian illumination. The integrated polarization of Tau A at 33 GHz was found to be 7.8 ± 0.6 per cent at position angle =148°± 3°.     

Changes in European temperature extremes can be predicted from changes in PDF central statistics

Although uncertainties are still large, many potentially dangerous effects have already been identified concerning the impacts of global warming on human societies. For example, the record-breaking 2003 summer heat wave in Europe has given a glimpse of possible future European climate conditions. Here we use an ensemble of regional climate simulations for the end of the twentieth and twenty-first centuries over Europe to show that frequency, length and intensity changes in warm and cold temperature extremes can be derived to a close approximation from the knowledge of changes in three central statistics, the mean, standard deviation and skewness of the Probability Distribution Function, for which current climate models are better suited. In particular, the effect of the skewness parameter appears to be crucial, especially in the case of cold extremes, since it mostly explains the relative warming of these events compared to the whole distribution. An application of this finding is that the future impacts of extreme heat waves and cold spells on non-climatological variables (e.g., mortality) can be estimated to a first-order approximation from observed time series of daily temperature transformed in order to account for simulated changes in these three statistics.     

Preservice Primary Teachers’ Depth and Accuracy of Knowledge of Tropical Cyclones

Climatic hazards are a key feature of life. It is vital that teachers are knowledgeable about these phenomena in order to develop their students’ understanding of them. This study used a mixed methods approach to examine the accuracy and depth of preservice primary teachers’ (n = 430) knowledge of tropical cyclones. The findings suggest that prospective primary teachers hold alternative conceptions about the causes, spatial distribution, and impacts of these phenomena and that their explanations of processes lack structural complexity and integration. Issues raised by these findings and implications for teachers’ geographical knowledge and their professional standards and preservice teacher education are discussed.     

The carbohydrate‐to‐protein ratio as a biological indicator of water movement

We investigated temporal (day‐to‐day and season) and spatial (reach) variability of drift with the aim of guiding sampling protocol for quantifying drift at the whole river or reach scale. Overall, we found aquatic drift density and biomass varied considerably seasonally (CV = 72.9, 88.1) and to a lesser extent spatially (CV = 31.3, 30.7) and from day‐to‐day (CV = 45.2, 39.4). Although spatial and day‐to‐day variation in drift density and biomass were similar, sampling logistics suggest spatial sampling would be more cost‐effective and less time consuming. Drift density and biomass estimated from top samplers was often higher than estimates from samplers near the streambed or mid‐water column. A reliable estimate of mean densities and biomass at a site may require only two samplers— a top sampler and either a middle or bottom sampler. In our study, we calculated that sampling at four sites over 1 or 4 days at one site would be required to obtain a 95% CI within 50% of the mean drift density. Eight sites over 1 or 10 days at one site would be required to achieve a 95% CI within 25% of the mean drift density.     

Microstructures of phosphatic porcelain from sintering to vitrification: Evidence from sherds excavated in Charleston,South Carolina

Eight phosphatic porcelain sherds recovered from various historical sites in Charleston were analyzed by electron microprobe. Some sherds contain sulfur (2.3–3.1wt.% SO₃); others contain only traces of this component. The analytical data suggest that the sulfurous sherds are Bow porcelain (London, Bowcock period, ca. 1755–1769). The origin(s) of the low‐S samples remains unidentified; one compositionally resembles “gold‐anchor period” (phosphatic) Chelsea porcelain (London, ca. 1756–1769) but its decoration is inconsistent with known wares produced by this factory during that era. The degree of vitrification is highly variable, particularly among the SO₃‐poor samples. The melt phase is strongly enriched in incompatible elements (Ti, Fe, Na, K). The phosphate phase [calcined bone ash (hydroxyapatite)] in poorly vitrified samples hosts minute melt blebs, but remains porous. With increasing vitrification, these melt blebs increase in size and begin to coalesce, ultimately forming ameboid patches up to ∼10 μm in diameter. In the most vitrified samples, the coalesced melt “leaks” into the matrix, leaving behind a phosphate phase that lacks pores and melt and has a lower CaO/P₂O₅ ratio (=2.7, molecular proportions) than either hydroxyapatite (3.3) or β‐whitlockite (3.0). The two varieties of phosphate occur in some poorly vitrified samples, suggesting the recycling of high‐fired wasters (as “grog”) in their ceramic pastes. Melt compositions vary with contiguous mineralogy, accounting for their divergence from the ternary eutectic in the Ca₃(PO₄)₂‐CaAl₂Si₂O₈‐SiO₂ system. The resorption of phosphate by the matrix melt virtually precludes recognition of anorthite formed by the “non‐phosphate glass equation.” © 2011 Wiley Periodicals, Inc.     

Hydrogen peroxide concentrations in the Peru upwelling area

The concentration of hydrogen peroxide was measured in waters off the coast of Peru during June and July 1983. The study period coincided with the end of the 1982/83 El Niño and the onset of coastal upwelling. Depth profiles of hydrogen peroxide concentration exhibit surface maxima and decrease with depth to the base of the mixed layer. Surface peroxide concentrations ranged from 0.8 to 5 × 10^?8 M. Below the mixed layer hydrogen peroxide was below the detection limit (5 × 10^?9 M). Diel variations were observed, with surface peroxide levels increasing during the day and decreasing at night. The nearshore station exhibited lower hydrogen peroxide concentrations than offshore stations, a reversal of the trend found in other coastal regions. This is attributed to the lack of coastal vegetation and runoff, and to active coastal upwelling of deeper water with low hydrogen peroxide concentrations.     

Population Health, Environment and Economic Development

There are fundamental links between population health, environment and economic development. The ultimate goal of economic development is to improve the quality of human life and increase people's longevity. This goal cannot be achieved without a clean and prosperous Earth. There has been increasing evidence showing that the expansion of economic activities can have significant impacts on the environment and can cause large-scale and sometimes irreversible environmental changes. It is beyond reasonable doubt that these changes will have serious public health consequences. How to tackle these issues is a unprecedented challenge to scientists and policy-makers. This revised version was published online in July 2006 with corrections to the Cover Date.     

<Emphasis Type="Italic">sub</Emphasis>ATTO indoor GPS – pitfalls,solutions and performance using a conventional correlator

A key requirement for emergency call location (e.g. E911), for robust operation of location-based m-commerce systems and for telematics systems is that the location technology be able to operate in urban canyons and inside buildings. We start from a definition of the target environments, which includes multi-level parking garages, office buildings and homes, but not underground parking garages or tunnels. Based on experience in these target environments and understanding of typical applications we derive specific requirements for sensitivity and acquisition speed. The primary problems associated with weak signal operation are as follows. (1) In conventional GPS receivers sampling at the correlator output typically occurs at a sampling interval of the order of 1 ms. With weak signals, however, the signal-to-noise ratio of these samples is too low to support lock-in of a phase-locked or frequency-locked loop. (2) With weak signals, the signal-to-noise ratio is too low to support the extraction of the 50BPS navigation message from the signal. Therefore, aiding data is required from an external source. (3) Because the data cannot be extracted, it is not possible for the receiver to synchronize to the incoming bits, words or subframes. Therefore, it is not possible to construct pseudoranges without prior information. (4) The paper describes Sigtec Navigation's subATTO technology. This technology provides sensitivity down to –185 dBW (19 dBHz assuming NF of 1.5 dB and no other implementation loss). This is 5 dB below an attoWatt (10^–18 W) and has been shown to provide reliable positioning inside buildings, multi-level parking garages and in urban canyons without any aiding at all. The paper describes the patented signal processing scheme, how ambiguity resolution and time synchronization are achieved, the wireless assistance technique, the acquisition strategy and the use of scanning channels. Results are presented from trials in a multi-level parking garage. The results obtained in most parking garages are similar to these in terms of availability of fixes, signal strengths received and location accuracy achieved. The performance achieved in multi-level parking garages is rarely worse than this. One of the major impediments to practical application of weak signal-processing schemes is the limited dynamic range imposed by the GPS C/A code signal structure. This problem is discussed along with the problems of multipath distortion in the context of telematics operation in urban canyons. A realistic urban accuracy goal of 20 m for 95% of fixes is proposed based on experience with GPS and dead reckoning. Enhancements under development will provide sensitivity of –188 dBW, which will provide continuous availability within a broader range of indoor environments. For practical applications, this will require the use of modern 'search engine' hardware for acceptable acquisition speed. As the paper shows, this sensitivity is near the practical limit of sensitivity with acceptable acquisition times and dynamic capability. Electronic Publication