Monitoring mixed sand and gravel beaches using unmanned aerial systems

Mixed sand-gravel beaches act as an efficient natural sea defence and are increasingly managed by beach recharge, which can alter the sediment size composition of such beaches and their profile response. This creates an urgent need for better information about the behaviour of mixed sand and gravel beaches after recharge. UAS promise to be a promising novel tool in this context. To test their suitability for routine surveying, we aligned an experimental UAS survey along the standard monitoring schedule that was in operation for a mixed beach in East Sussex, UK. High wind speeds at the time of deployment significantly affected the data collection, but it was possible to generate (i) a surface model using Structure-from-Motion-based photogrammetry and (ii) an image mosaic that clearly identifies the spatial patterns of the sand-gravel mix of the beach. This indicates that UAS offer substantial potential for beach monitoring. However, an unclear legal framework acts and the sensitivity of platforms to high winds sets clear limits for UAS to serve as a stand-alone monitoring tool for beach environments at the present time

Sexual conflict over copula timing: a mathematical model and a test in the yellow dung fly

Sexual conflict over mating occurrence, timing, or duration is common in animals. This explains conspicuous female mate rejection behavior in many species, often involving shaking, fighting, and occasional forced copulations. We present a simple model that generates predictions about whether and when copulation occurs in such conflict situations and how much female rejection behavior should be observed. Predictions depend on 2 underlying parameters affecting female resistance and male persistence. We supply 2 qualitative tests of the model using the yellow dung fly Scathophaga stercoraria (Diptera: Scathophagidae). We manipulated adult age, body size (large and small), and adult food availability (low and high), independently in males and females, staging replicate pairings of all treatment combinations. In agreement with predictions of our model, shaking duration first increased to a maximum at intermediate age, when the average female copulated, and then decreased again. Contrary to expectation, body size did not affect copulation timing, female resistance, or male persistence. As predicted, adult food limitation delayed sexual maturity and hence prolonged female resistance, resulting in later copulations after more shaking. However, although food limitation equally delayed the increase in male persistence with age, copulation also occurred later after more shaking, opposite to the model prediction. We conclude that shaking is driven primarily by female age and male responses to it. Although female shaking can initially successfully deter males in S. stercoraria, this behavior is subtle and has apparently shifted function from an effective means of mate choice to a signal of nonreceptivity, though its importance in nature remains unclea

Higgs Sector in Extensions of the MSSM

Extensions of the Minimal Supersymmetric Standard Model (MSSM) with additional singlet scalar fields solve the important mu-parameter fine tuning problem of the MSSM. We compute and compare the neutral Higgs boson mass spectra, including one-loop corrections, of the following MSSM extensions: Next-to-Minimal Supersymmetric Standard Model (NMSSM), the nearly-Minimal Supersymmetric Standard Model (nMSSM), and the U(1)'-extended Minimal Supersymmetric Standard Model (UMSSM) by performing scans over model parameters. We find that the Secluded U(1)'-extended Minimal Supersymmetric Standard Model (sMSSM) is identical to the nMSSM if three of the additional scalars decouple. The dominant part of the one-loop corrections are model-independent since the singlet field does not couple to MSSM particles other than the Higgs doublets. Thus, model-dependent parameters enter the masses only at tree-level. We apply constraints from LEP bounds on the Standard Model and MSSM Higgs boson masses and the MSSM chargino mass, the invisible Z decay width, and the Z-Z' mixing angle. Some extended models permit a Higgs boson with mass substantially below the SM LEP limit or above theoretical limits in the MSSM. Ways to differentiate the models via masses, couplings, decays and production of the Higgs bosons are discussed.Comment: 65 pages, 15 figures. Figure replaced and typos corrected. Version to appear in Phys. Rev.

Masked millennial-scale climate variations in South West Africa during the last glaciation

To address the connection between tropical African vegetation development and high-latitude climate change we present a high-resolution pollen record from ODP Site 1078 (off Angola) covering the period 50–10 ka BP. Although several tropical African vegetation and climate reconstructions indicate an impact of Heinrich Stadials (HSs) in Southern Hemisphere Africa, our vegetation record shows no response. Model simulations conducted with an Earth System Model of Intermediate Complexity including a dynamical vegetation component provide one possible explanation. Because both precipitation and evaporation increased during HSs and their effects nearly cancelled each other, there was a negligible change in moisture supply. Consequently, the resulting climatic response to HSs might have been too weak to noticeably affect the vegetation composition in the study area. Our results also show that the response to HSs in southern tropical Africa neither equals nor mirrors the response to abrupt climate change in northern Africa

Vitamins and Perinatal Outcomes Among HIV-Negative Women in Tanzania.

Prematurity and low birth weight are associated with high perinatal and infant mortality, especially in developing countries. Maternal micronutrient deficiencies may contribute to these adverse outcomes. In a double-blind trial in Dar es Salaam, Tanzania, we randomly assigned 8468 pregnant women (gestational age of fetus, 12 to 27 weeks) who were negative for human immunodeficiency virus infection to receive daily multivitamins (including multiples of the recommended dietary allowance) or placebo. All the women received prenatal supplemental iron and folic acid. The primary outcomes were low birth weight (<2500 g), prematurity, and fetal death. The incidence of low birth weight was 7.8% among the infants in the multivitamin group and 9.4% among those in the placebo group (relative risk, 0.82; 95% confidence interval [CI], 0.70 to 0.95; P=0.01). The mean difference in birth weight between the groups was modest (67 g, P<0.001). The rates of prematurity were 16.9% in the multivitamin group and 16.7% in the placebo group (relative risk, 1.01; 95% CI, 0.91 to 1.11; P=0.87), and the rates of fetal death were 4.3% and 5.0%, respectively (relative risk, 0.87; 95% CI, 0.72 to 1.05; P=0.15). Supplementation reduced both the risk of a birth size that was small for gestational age (<10th percentile; 10.7% in the multivitamin group vs. 13.6% in the placebo group; relative risk, 0.77; 95% CI, 0.68 to 0.87; P<0.001) and the risk of maternal anemia (hemoglobin level, <11 g per deciliter; relative risk, 0.88; 95% CI, 0.80 to 0.97; P=0.01), although the difference in the mean hemoglobin levels between the groups was small (0.2 g per deciliter, P<0.001). Multivitamin supplementation reduced the incidence of low birth weight and small-for-gestational-age births but had no significant effects on prematurity or fetal death. Multivitamins should be considered for all pregnant women in developing countries. (ClinicalTrials.gov number, NCT00197548 [ClinicalTrials.gov].)

Effect of growth media on the early performance of Prosopis africana (Guill. and Perr.) Taub. seedlings

This study examined the performance of Prosopis africana seedlings raised under different growth media. The experiment was laid in a completely randomized design with three treatments (topsoil, mixture of topsoil and poultry droppings, and mixture of topsoil and cow dung). Each treatment was replicated 4 times and each replicate had 10 potted seedlings making a total of 120 seedlings. The seedling growth variables; heights (cm) collar diameters (cm), number of leaves data were collected every 3 days for 12 weeks. The data collected were subjected to analysis of variance and significant means were separated using Duncan multiple range test at 0.05 significant level. The result showed significant difference (p=0.005) in the height of seedlings. No significant difference existed in the seedlings collar diameter (p=0.306) and number of leaves (p=0.957). The follow-up result indicated that there was no significant difference (p&gt;0.05) in the height of seedlings raised in mixture of topsoil and poultry droppings (Mean ± standard error =105.87±5.40a) and topsoil (105.18±4.27a). However, a significant difference (p&gt;0.05) existed between both treatments and mixture of topsoil and cow dung (86.36±4.90b). Seedlings raised in the mixture of topsoil and poultry droppings had the best performance. The study therefore, recommended raising Prosopis africana seedling with topsoil for reduced cost of production. DOI: http://dx.doi.org/10.5281/zenodo.398093

Comparative beach surveys using an unmanned aerial system, ground-based GPS, terrestrial laser scanning, and airborne laser scanning

Profiles and sediment size distribution on mixed sand and gravel beaches are highly variable, both spatially and temporally, and cost-effective high-resolution monitoring schemes are needed to capture this variability. The potential for the use of UAS for coastal monitoring remains relatively untested in comparison to established remote sensing techniques. This paper reports on a field experiment in Pevensey Bay, East Sussex, England, in which simultaneous measurements were carried out using UAV-based photogrammetry, RTK-GPS, and both terrestrial and airborne laser scanning. The central objective of this research was to compare the accuracy of the TLS, ALS, and UAV-based surface modelling to draw conclusions for operational beach monitoring. The analysis was carried out through point cloud inter-comparison, comparison of point cloud performance against RTK-GPS transect data, and evaluation of differences between elevation models that were generated based on the point clouds. The point cloud comparison focused on the vertical differences between respective data sets, and showed that the UAV-based point cloud had positive offsets of 9cm (RMS 10cm) and 6cm (RMS 8cm) compared to the TLS and ALS point clouds, respectively. Analysis was also carried out to evaluate the extent to which surface sediment characteristics affected measurement accuracy of the different methods. Data comparison on beach gravel, beach sand, cobble, foreshore dry sand, foreshore wet sand and soft mud showed the best agreement between UAV, TLS and ALS data on gravel beach sections. For nearly all surface types UAV and ALS data showed better agreement than UAV to TLS data