Vocal competition in male Xenopus laevis frogs

Male Xenopus laevis frogs produce underwater advertisement calls that attract gravid females and suppress calling by male competitors. Here we explore whether groups of males establish vocal ranks and whether auditory cues alone suffice for vocal suppression. Tests of male–male pairs within assigned groups reveal linear vocal dominance relations, in which each male has a defined rank. Both the duration over which males interact, as well as the number of competitive opportunities, affect linearity. Linear dominance across the group is stable for about 2 weeks; rank is dynamic. Males engage in physical interactions (clasping) while paired but clasping and vocal rank are not correlated. Playbacks of advertisement calls suppress calling and calls from high- and low-ranking males are equally effective. Thus, auditory cues alone suffice to suppress vocal behavior. Playback intensities equivalent to a nearby male advertising effectively suppress calling while low-intensity playbacks are either ineffective or stimulate vocal behavior. X. laevis advertisement calls are biphasic, composed of alternating fast and slow click trills. Approximately half the males tested are more vocally suppressed by all slow than by all fast trills; thus, these males can distinguish between the two phases. The fully aquatic family Pipidae diverged from terrestrial ancestors approximately 170 mya. Vocal suppression in the X. laevis mating system may represent the translation of an ancient anuran social strategy to underwater life.     

Nineteenth-century land-use legacies affect contemporary land abandonment in the Carpathians

Regional Environmental Change - Historical land use may shape landscapes for centuries into the future, but it remains unclear how much land-use legacies affect contemporary land use. Knowing for...     

Monosomy 8q: Prenatal diagnosis and autopsy findings

The autopsy findings of a fetus with deletion of the long arm of chromosome 8 are described. Many of the features are similar to those of the tricho-rhino-phalangeal syndromes, types I and II, which are associated with deletions on chromosome 8q24. Other findings in this case, such as total absence of the corpus callosum and intestinal malrotation, have not been described in these syndromes. Genes involved in the development of the latter malformations may reside in adjacent regions on the long arm of chromosome 8. An elevated serum level of beta human chorionic gonadotropin (βhCG) was found during pregnancy. This aberration should be included with other chromosomal disorders which may be detected by this test.     

Determination of mono-, di- and trinitronaphthalenes in soil samples contaminated by explosives

We investigated the extraction of eight mono-, di- and trinitronaphthalenes from soil samples by ultrasonic, respectively, soxhlet extraction. Sonication was the more convenient procedure with a usually higher repeatability than the soxhlet method. All extracts were analysed by high-performance liquid chromatography with diode array detection. These methods were used to determine the concentration of nitronaphthalenes in five soil samples polluted by explosives. The most abundant contaminants were 1,5- and 1,8-dinitronaphthalene as well as 1,3,5-, 1,3,8- and 1,4,5-trinitronaphthalene. In all samples the sum of trinitronaphthalenes exceeded the sum of mono- and dinitronaphthalenes. It is recommendable to include these eight compounds in the analytical exploration of sites contaminated by explosives.     

Detection of the toughest: Pedestrian injury risk as a smooth function of age

Objective: Though it is common to refer to age-specific groups (e.g., children, adults, elderly), smooth trends conditional on age are mainly ignored in the literature. The present study examines the pedestrian injury risk in full-frontal pedestrian-to–passenger car accidents and incorporates age—in addition to collision speed and injury severity—as a plug-in parameter.

Methods: Recent work introduced a model for pedestrian injury risk functions using explicit formulae with easily interpretable model parameters. This model is expanded by pedestrian age as another model parameter. Using the German In-Depth Accident Study (GIDAS) to obtain age-specific risk proportions, the model parameters are fitted to the raw data and then smoothed by broken-line regression.

Results: The approach supplies explicit probabilities for pedestrian injury risk conditional on pedestrian age, collision speed, and injury severity under investigation. All results yield consistency to each other in the sense that risks for more severe injuries are less probable than those for less severe injuries. As a side product, the approach indicates specific ages at which the risk behavior fundamentally changes. These threshold values can be interpreted as the most robust ages for pedestrians.

Conclusions: The obtained age-wise risk functions can be aggregated and adapted to any population. The presented approach is formulated in such general terms that in can be directly used for other data sets or additional parameters; for example, the pedestrian's sex. Thus far, no other study using age as a plug-in parameter can be found.     

Denitrification across landscapes and waterscapes: a synthesis.

Denitrification is a critical process regulating the removal of bioavailable nitrogen (N) from natural and human-altered systems. While it has been extensively studied in terrestrial, freshwater, and marine systems, there has been limited communication among denitrification scientists working in these individual systems. Here, we compare rates of denitrification and controlling factors across a range of ecosystem types. We suggest that terrestrial, freshwater, and marine systems in which denitrification occurs can be organized along a continuum ranging from (1) those in which nitrification and denitrification are tightly coupled in space and time to (2) those in which nitrate production and denitrification are relatively decoupled. In aquatic ecosystems, N inputs influence denitrification rates whereas hydrology and geomorphology influence the proportion of N inputs that are denitrified. Relationships between denitrification and water residence time and N load are remarkably similar across lakes, river reaches, estuaries, and continental shelves. Spatially distributed global models of denitrification suggest that continental shelf sediments account for the largest portion (44%) of total global denitrification, followed by terrestrial soils (22%) and oceanic oxygen minimum zones (OMZs; 14%). Freshwater systems (groundwater, lakes, rivers) account for about 20% and estuaries 1% of total global denitrification. Denitrification of land-based N sources is distributed somewhat differently. Within watersheds, the amount of land-based N denitrified is generally highest in terrestrial soils, with progressively smaller amounts denitrified in groundwater, rivers, lakes and reservoirs, and estuaries. A number of regional exceptions to this general trend of decreasing denitrification in a downstream direction exist, including significant denitrification in continental shelves of N from terrestrial sources. Though terrestrial soils and groundwater are responsible for much denitrification at the watershed scale, per-area denitrification rates in soils and groundwater (kg N x km(-2) x yr(-1)) are, on average, approximately one-tenth the per-area rates of denitrification in lakes, rivers, estuaries, continental shelves, or OMZs. A number of potential approaches to increase denitrification on the landscape, and thus decrease N export to sensitive coastal systems exist. However, these have not generally been widely tested for their effectiveness at scales required to significantly reduce N export at the whole watershed scale.     

The efficiency of the multi-walled carbon nanotubes used for antibiotics removal from wastewaters generated by animal farms

Environmental Science and Pollution Research - In the recent years, residual antibiotics are considered to be emerging environmental pollutants due to their continuous input and persistence into...