Implications of short-range spatial variation of soil bulk density for adequate field-sampling protocols: methodology and results from two contrasting soils

Soil bulk density (BD) is measured during soil monitoring. Because it is spatially variable, an appropriate sampling protocol is required. This paper shows how information on short-range variability can be used to quantify uncertainty of estimates of mean BD and soil organic carbon on a volumetric basis (SOCv) at a sampling site with different sampling intensities. We report results from two contrasting study areas, with mineral soil and with peat. More sites should be investigated to develop robust protocols for national-scale monitoring, but these results illustrate the methodology. A 20 × 20-m2 monitoring site was considered and sampling protocols were evaluated under geostatistical models of our two study areas. At sites with local soil variability comparable to our mineral soil, sampling at 16 points (4 × 4 square grid of interval 5 m) would achieve a root mean square error (RMSE) of the sample mean value of both BD and SOCv of less than 5% of the mean (topsoil and subsoil). Pedotransfer functions (PTFs) gave predictions of mean soil BD at a sample site, comparable to our study area on mineral soil, with similar precision to a single direct measurement of BD. On peat soils comparable to our second study area, the mean BD for the monitoring site at depth 0–50 cm would be estimated with RMSE to be less than 5% of the mean with a sample of 16 cores, but at greater depths this criterion cannot be achieved with 25 cores or fewer

Managing native and non-native sea lamprey (Petromyzon marinus) through anthropogenic change: A prospective assessment of key threats and uncertainties.

Sea lamprey (Petromyzon marinus) is a species of conservation concern in their native range of the Atlantic coasts of Europe (Near Threatened to Critically Endangered) and North America (Secure to Critically Imperiled), and an invasive species of great economic and ecological concern in the Laurentian Great Lakes. Despite differences in life history strategy (anadromous natives vs adfluvial non-natives), the biology of sea lamprey is sufficiently similar to expect comparable responses to large-scale environmental change. We take a prospective look at the future (50 to 100 years) of sea lamprey management in an era of considerable environmental disturbance, and consider biological responses, management actions, and the future status of populations across the native and non-native ranges. Based on facilitated discussion by a diverse group of international experts, two major but poorly characterized classes of threats to sea lamprey were identified: climate change and socio-political issues. We discuss how climate induced changes affect growth, bioenergetics, and phenology of sea lamprey, and associated effects on control tactics (pesticides and barriers) and conservation. We consider tensions surrounding improving connectivity in the Great Lakes while controlling invasive sea lamprey, and discuss supplements and alternatives to pesticides and their wider effect, as well as the effects of new invasive species. To prevent the extirpation of native sea lamprey populations, or the re-expansion of non-native populations, we conclude with a call for new and ongoing dialogue and collaboration among all sea lamprey biologists and managers across the native and non-native range

Early, regular breast-milk pumping may lead to early breast-milk feeding cessation

Objective To estimate the effect of early, regular breast-milk pumping on time to breast-milk feeding (BMF) and exclusive BMF cessation, for working and non-working women.Design Using the Infant Feeding Practices Survey II (IFPS II), we estimated weighted hazard ratios (HR) for the effect of regular pumping (participant defined) compared with non-regular/not pumping, reported at month 2, on both time to BMF cessation (to 12 months) and time to exclusive BMF cessation (to 6 months), using inverse probability weights to control confounding.Setting USA, 2005-2007.Subjects BMF (n 1624) and exclusively BMF (n 971) IFPS II participants at month 2.Results The weighted HR for time to BMF cessation was 1·62 (95 % CI 1·47, 1·78) and for time to exclusive BMF cessation was 1·14 (95 % CI 1·03, 1·25). Among non-working women, the weighted HR for time to BMF cessation was 2·05 (95 % CI 1·84, 2·28) and for time to exclusive BMF cessation was 1·10 (95 % CI 0·98, 1·22). Among working women, the weighted HR for time to BMF cessation was 0·90 (95 % CI 0·75, 1·07) and for time to exclusive BMF cessation was 1·14 (95 % CI 0·96, 1·36).Conclusions Overall, regular pumpers were more likely to stop BMF and exclusive BMF than non-regular/non-pumpers. Non-working regular pumpers were more likely than non-regular/non-pumpers to stop BMF. There was no effect among working women. Early, regular pumpers may need specialized support to maintain BMF

Logic Programming and Logarithmic Space

We present an algebraic view on logic programming, related to proof theory and more specifically linear logic and geometry of interaction. Within this construction, a characterization of logspace (deterministic and non-deterministic) computation is given via a synctactic restriction, using an encoding of words that derives from proof theory. We show that the acceptance of a word by an observation (the counterpart of a program in the encoding) can be decided within logarithmic space, by reducing this problem to the acyclicity of a graph. We show moreover that observations are as expressive as two-ways multi-heads finite automata, a kind of pointer machines that is a standard model of logarithmic space computation