A trend test for the analysis of multiple paternity

The aquatic warbler, Acrocephalus paludicola, is one of a few species in which nestlings from a single nest can be sired by up to four different fathers. Data from a DNA fingerprinting study suggest that there is a trend: the larger the number of fathers in a brood the larger is the number of nestlings. However, the number of young within a single nest cannot be smaller than the number of fathers. This restriction causes an inherent trend and, consequently, can lead to a false-positive trend test result. For this nonstandard situation, we propose a trend test that differentiates between the inherent trend and a “real” trend, that is, a larger brood size through multiple paternity. Using DNA fingerprinting data, we performed a randomization test using the proposed new trend test statistic and obtained a significant result (P=0.047). This indicates that a larger number of fathers per brood is associated with a larger brood size. In addition, we consider an umbrella alternative, that is, a downturn in effect may occur after the optimal number of fathers per brood is exceeded. An appropriate test for this alternative also leads to a significance (P=0.011).     

Modelling cation exchange in columns of disturbed and undisturbed subsoil

Cation exchange is often studied with disturbed and dried soils, but the applicability of the results to undisturbed soils is not straightforward. We investigated the value of exchange coefficients obtained from standard procedures for predicting cation exchange in soil. Columns of undisturbed and disturbed subsoil of a Luvisol (SBt horizon) were leached under saturated conditions with 0.4, 4, 20, 41, 102 and 205 mm BaCl₂ at a Darcy velocity of 1400 mm day^?1. The model PHREEQC was used to calculate one‐dimensional transport, inorganic complexation and multiple cation exchange. Two model variants were tested: m1 (exchangeable cations obtained by percolation with NH₄Cl) and m2 (exchangeable cations obtained by shaking the soil with BaCl₂). The exchange coefficients (Gaines–Thomas formalism) were calculated from the ion activities in solution and exchangeable cations obtained by NH₄Cl percolation (m1) or shaking with BaCl₂ (m2). Variant m1 predicted cation exchange of the disturbed (homogenized) soil for the entire BaCl₂ concentration range, whereas variant m2 resulted in a two‐fold overestimation of desorbed K for all experiments, which was related to large amounts of K released from the soil by shaking with BaCl₂. In experiments with undisturbed soil, variant m1 predicted the concentrations of Mg, Ca, K, and Na in the solution phase and the sum of cations released from exchange sites. However, variant m2 predicted changes in ion concentrations and exchangeable cations somewhat less well. This study suggests that the amounts of exchangeable cations and exchange coefficients obtained from experiments with homogenized soil by percolation are useful to predict cation concentrations in column experiments with undisturbed soils.     

Die Veränderung der Phosphatintensität der Bodenlösung eines Pelosol-Pseudogleys nach Grünlandumbruch

Long-term change in phosphate intensity in a clay soil after turning grassland into arable land In a 7years field experiment on a poorly drained clay (Pelosol-Pseudogley) after turning permanent grassland into arable land, the phosphate concentration in the soil solution (P_l) decreased and P retention (P_s) increased even if as much as 265 kg P ha^?1 was added in excess of plant uptake. Neither loss in organic matter nor disaggregation of the well aggregated grassland soil by soil management seemed to be responsible for this decrease in P_l. Instead, a slight increase in pH within the 7 years and, to a lesser extent, a concomitant increase in exchangeable Ca are assumed to have caused the decrease in P_l. Laboratory experiments in which pH, exchangeable Ca and ionic strength were varied support the field results. A multiple correlation between P_l and pH plus exchangeable Ca explained 89% of the variation of P_l whereas pH and Ca alone explained only 76 and 42%, respectively. Solubility data placed the solutions around the hydroxyapatite (HA) isotherm even when P-fertilizer were added in excess of plant uptake. It seems unlikely, therefore that HA governs P_l in this soil. Instead, the results are in favour of surface P adsorption to determine P_l. The effect of exchangeable Ca and ionic strength is then explained by their effects on the thickness of the electric double layer which in turn influences P adsorption.     

30,000 years of hydrothermal activity at the lost city vent field

Strontium, carbon, and oxygen isotope data and radiocarbon ages document at least 30,000 years of hydrothermal activity driven by serpentinization reactions at Lost City. Serpentinization beneath this off-axis field is estimated to occur at a minimum rate of 1.2 x 10(-4) cubic kilometers per year. The access of seawater to relatively cool, fresh peridotite, coupled with faulting, volumetric expansion, and mass wasting processes, are crucial to sustain such systems. The amount of heat produced by serpentinization of peridotite massifs, typical of slow and ultraslow spreading environments, has the potential to drive Lost City-type systems for hundreds of thousands, possibly millions, of years.     

Real-space observation of molecular motion induced by femtosecond laser pulses

Femtosecond laser irradiation is used to excite adsorbed CO molecules on a Cu110 surface; the ensuing motion of individual molecules across the surface is characterized on a site-to-site basis by in situ scanning tunneling microscopy. Adsorbate motion both along and perpendicular to the rows of the Cu110 surface occurs readily, in marked contrast to the behavior seen for equilibrium diffusion processes. The experimental findings for the probability and direction of the molecular motion can be understood as a manifestation of strong coupling between the adsorbates' lateral degrees of freedom and the substrate electronic excitation produced by the femtosecond laser radiation.     

Thorium-230 ages of corals and duration of the last interglacial sea-level high stand on oahu, hawaii

Thorium-230 ages of emergent marine deposits on Oahu, Hawaii, have a uniform distribution of ages from approximately 114,000 to approximately 131,000 years, indicating a duration for the last interglacial sea-level high stand of approximately 17,000 years, in contrast to a duration of approximately 8000 years inferred from the orbitally tuned marine oxygen isotope record. Sea level on Oahu rose to >/=1 to 2 meters higher than present by 131,000 years ago or approximately 6000 years earlier than inferred from the marine record. Although the latter record suggests a shift back to glacial conditions beginning at approximately 119,000 years ago, the Oahu coral ages indicate a near present sea level until approximately 114,000 years ago.     

Removal of an intracoelomic hook via laparotomy in a sandbar shark (Carcharhinus plumbeus)

A twenty-one-year-old male sandbar shark (Carcharhinus plumbeus) demonstrated signs of chronic weight loss even though its appetite remained unchanged. In addition, the gradual development of a red, circular lesion on its ventral body was noted. After months without any significant changes, a ventral fistula appeared revealing the tip of a wire exposed within its center. The shark was immobilized via intramuscular remote injection through dartgun with etomidate; removed from its exhibit tank; and clinically examined with radiographic imaging, a cell blood count/serum chemistry evaluation, and the use of a metal detector along the body wall. A metallic hook was identified in the coelom about 10 cm cranial to the external fistula. The shark was transferred to an isolation pool for 1 mo. A second immobilization via immersion in eugenol was conducted in order to perform a celiotomy. The hook was located in a liver lobe and was surgically removed. After a prolonged recovery from anesthesia, the shark was released into its primary tank and recovered uneventfully, although some of the skin sutures sloughed prematurely.     

Hydrological structure and erosion damage caused by concentrated flow in cultivated catchments

This study analyses the between-catchment variability of rill volumes produced by concentrated flow erosion during winter in the northern part of the Paris Basin. The working hypotheses were that (i) runoff concentrates along channels determined by topography or by agricultural practices; (ii) rill length is a major component of rill volume variability on a catchment scale; (iii) rill cross-sectional areas are controlled by the size of upslope runoff-contributing areas connected to the corresponding channels. Two samples, one of 20 zero order catchments and the other of 15 catchments, were surveyed. For each catchment, the runoff collector network was modelled from topographical and agricultural information, and split into homogeneous segments. Each segment was characterized by its slope gradient (SL), the soil susceptibility to rill erosion (SSE) and the size of the upslope runoff-contributing areas (RCA) connected to it. These areas were identified by the structural state of their soil surface. The frequency of rill occurrence was highly correlated with RCA and SL. The rill cross-sectional areas of eroded channels were correlated with RCA, SL and SSE. Catchment erosion rates were estimated by adding together the predicted rill volumes for each segment within the catchment. These estimations were closely correlated with observed rill erosion rates. The relative spatial position of runoff collectors must be taken into account when examining the damage caused by concentrated flow erosion.