Search results for "feature"

The anthropogenic sealing of soils in urban areas

2009

The sealing of soils by impervious materials is, normally, detrimental to its ecological functions. Exchanges of energy, water and gases are restricted or hampered and an increasing pressure is being exerted on adjacent, non sealed areas. The negative effects span from loss of plant production and natural habitats to increased floods, pollution, and health risks and consequently higher social costs. Environmental Agencies produce periodical reports where the phenomenon of soil consumption by urban infrastructures is monitored with extremely sophisticated geographical tools but little specific research is available that describes the effects of soil sealing. This paper reviews some recent co…

2015

The combination of local orientation collinearity and spatial frequency contrast in contour integration was studied in two experiments using a 2AFC contour detection and discrimination task. Target contours were defined by local orientation collinearity, spatial frequency contrast between contour and background elements, or both cues. Experiments differed in the source of spatial frequency contrast by manipulating the spatial frequency of either contour or background elements. Cue summation gains, defined as the performance benefit of double cue conditions over single cue conditions, were evaluated and tested against the predictions derived from probability summation and linear summation. S…

Inverting the Wollaston Illusion: Gaze Direction Attracts Perceived Head Orientation

2021

In the early 19th century, William H. Wollaston impressed the Royal Society of London with engravings of portraits. He manipulated facial features, such as the nose, and thereby dramatically changed the perceived gaze direction, although the eye region with iris and eye socket had remained unaltered. This Wollaston illusion can be thought of as head orientation attracting perceived gaze direction when the eye region is unchanged. In naturalistic viewing, the eye region changes with head orientation and typically produces a repulsion effect. Here we explore if there is a flip side to the illusion. Does the gaze direction also alter the perceived direction of the head? We used copies of the o…

Genomic Data from an Ancient European Battlefield Indicates On-Going Strong Selection on a Genomic Region Associated with Lactase Persistence Over th…

2020

Lactase persistence (LP), the continued expression of lactase into adulthood, is the most strongly selected single gene trait over the last 10,000 years in multiple human populations. It has been posited that the primary allele causing LP among Eurasians, rs4988235*T (Enattah et al. 2008), only rose to appreciable frequencies during the Bronze and Iron Ages (Mathieson et al 2015; Olalde et al. 2018), long after humans started consuming milk from domesticated animals. This rapid rise has been attributed to an influx of peoples from the Pontic-Caspian steppe that began around 5,000 years ago (Allentoft et al. 2015; Furholt et al. 2016). We investigate the spatiotemporal spread of LP through a…

Geomorphological, chemical and physical study of “calanchi” landforms in NW Sicily (southern Italy)

2012

Abstract This work deals with an integrated geomorphological and chemical–physical study of “calanchi” landforms in two sites (Ottosalme and Catalfimo) of NW Sicily (southern Italy), developed on dominant silty-clay deposits. The calanchi fronts are characterized by different morphological features and dominant geomorphic processes. Sharp knife-edged ridges and concentrated water runoff dominate at Ottosalme, and smoother landforms affected by mass movements (mud flows and translational slides) prevail at Catalfimo. We focused on some geochemical and physical parameters such as pH , total dissolved salts, sodium adsorption ratio ( SAR ), porosity, plastic and liquid limits as possible cause…

On the formation of laminated sediments on the continental margin off Pakistan: the effects of sediment provenance and sediment redistribution

2001

Abstract The sedimentary processes and sediment sources contributing to the formation of laminated sediments along the upper slope off Pakistan are unravelled using inorganic bulk sediment geochemistry of 43 surface cores from the Pakistani continental margin and additional geochemical and Pb and Nd-isotope data for different types of layers. An important process everywhere along the margin is redeposition of fluvial-derived detritus from the shelf onto the slope. This process is of considerably higher intensity along the Makran margin than on the Indus margin. Trace element enrichment related to early diagenesis or surface productivity, which is commonly detectable in bulk sediment composi…

Climate signatures on decadal to interdecadal time scales as obtained from mollusk shells (Arctica islandica) from Iceland

2013

Abstract Pronounced decadal climate oscillations are detected in a multi-centennial record based on shell growth rates of the marine bivalve mollusk, Arctica islandica, from Iceland. The corresponding analysis of patterns in sea level pressure and temperature exhibit large-scale teleconnections with North Atlantic climate quantities. We find that the record projects onto blocking situations in the northern North Atlantic. The associated circulation shows a low-pressure signature over Greenland and the Labrador Sea and a high-pressure system over Western Europe associated with northeasterly flow towards Iceland and weakening in the westerly zonal flow over Europe. It can be speculated that s…

Studies on the effects of Ca2++ and Co++ on the swimming behavior of the blind Mexican cave fish

1992

The hypothesis that the blind cave fish (Astyanax hubbsi) adjusts the level of stimulation to its lateral line system (LLS) by varying its own velocity was examined. When the sensitivity of the LLS sense organs was reduced by lowering the Ca2+ concentration in the water or by adding Co2+ the fish compensated for this by swimming at a higher velocity.

The Forebrain of the Blind Cave Fish <i>Astyanax hubbsi </i>(Characidae)

1997

This paper presents a survey of the cell groups in the telencephalon of the teleost Astyanax hubbsi, based on series of transverse sections stained with the Nissl-, Kluver-Barrera and Bodian procedure

Quantification of the depletion of ozone in the plume of Mount Etna

2015

Volcanoes are an important source of inorganic halogen species into the atmosphere. Chemical processing of these species generates oxidised, highly reactive, halogen species which catalyse considerable O3 destruction within volcanic plumes. A campaign of ground-based in situ O3, SO2 and meteorology measurements was undertaken at the summit of Mount Etna volcano in July/August 2012. At the same time, spectroscopic measurements were made of BrO and SO2 columns in the plume downwind. Depletions of ozone were seen at all in-plume measurement locations, with average O3 depletions ranging from 11–35 nmol mol−1 (15–45%). Atmospheric processing times of the plume were estimated to be between 1 and …