Search results for "Spatial"

The Social Life of Viruses

2021

Despite their simplicity, viruses exhibit certain types of social interactions. Situations in which a given virus achieves higher fitness in combination with other members of the viral population have been described at the level of transmission, replication, suppression of host immune responses, and host killing, enabling the evolution of viral cooperation. Although cellular coinfection with multiple viral particles is the typical playground for these interactions, cooperation between viruses infecting different cells is also established through cellular and viral-encoded communication systems. In general, the stability of cooperation is compromised by cheater genotypes, as best exemplified…

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…

Bayesian estimation of partial population continuity using ancient DNA and spatially explicit simulations.

2017

Abstract The retrieval of ancient DNA from osteological material provides direct evidence of human genetic diversity in the past. Ancient DNA samples are often used to investigate whether there was population continuity in the settlement history of an area. Methods based on the serial coalescent algorithm have been developed to test whether the population continuity hypothesis can be statistically rejected by analysing DNA samples from the same region but of different ages. Rejection of this hypothesis is indicative of a large genetic shift, possibly due to immigration occurring between two sampling times. However, this approach is only able to reject a model of full continuity model (a tot…

GIS and the fractal formalisation of urban patterns : towards a new paradigm of spatial analysis

2000

Geographical distribution of unemployment in Italy. An Analysis of provincial differences in Italy

2007

Unemployment rates appear to vary widely at a subregional (e.g., local or provincial) level. Using spatial econometric models for spatial autocorrelation, this paper focuses attention on the spatial structure of regional unemployment disparities of Italian provinces. On the basis of findings from the economic literature and of the available socio-economic data, various model specifications, including different explanatory variables, are tested to investigate the geographical distribution of unemployment in the 103 provinces of Italy for the years 1998 and 2003. The results suggest that there is a clear explanation of unemployment differentials in terms of spatial equilibrium and disequilibr…

Ainavu ekoloģiskā plānošana un tās metodoloģiskie risinājumi mozaīkveida ainavās

2013

Elektroniskā versija nesatur pielikumus

On the discrimination of spatial intervals by the blind cave fish (Anoptichthys jordani).

1986

The performance of the blind cave fish in discriminating spatial intervals was investigated. The fish had to discriminate between pairs of grids consisting of equidistant vertical bars. The intervals between the bars on the grid to be chosen were kept constant while the intervals between the bars on the other grid were altered in steps so as to become gradually closer to the interval between the bars on the grid to be chosen. It was found that the fish were still able to discriminate between the two grids when the difference between the bar intervals amounted to at least 1.5 mm. In interpreting the results it was concluded that the phase information in the stimulus on the skin of the fish m…

NOTES ON THE BIOMETRY, ORIENTATION AND SPATIAL LOCALIZATION OF THE NESTS OF THE GLOBALLY NEAR-THREATENED STRAIGHT-BILLED REEDHAUNTER (LIMNOCTITES REC…

2017

We report the records of three nests of Straight-billed Reedhaunter, Limnoctites rectirostris, in southernmost Brazil. For each nest, we collected information about the biometry, spatial localization within the patch (border or inland) and cardinal orientation of the incubation chamber. Information on number of eggs and reproductive success is also presented. All nests were found early in September. The three nests were situated on the edge of patches and guided incubation chamber opening between north and east. All results are discussed. The information presented herein extends the scarce knowledge about the breeding biology of the Straight-billed Reedhaunter. Key words: breeding biology, …

Age and spatial structure of natural Pinus sylvestris stands in Latvia

2005

Abstract The age and spatial structure of six natural old growth Pinus sylvestris stands in Latvia were investigated, to attempt to identify retrospectively the past features of development. In each stand, one or two plots of size 200–900 m2 were established. Tree locations were mapped, stem diameter was measured, and tree age was determined from cores or by counting branch whorls. Tree distribution was assessed by Ripley's K function. A clumped spatial pattern was shown for P. sylvestris younger than 100 years. The temporal patterns of establishment could be partly linked to favourable climatic periods. The major disturbance affecting pine stands along the coast was windblown sand, which p…

Effect of restoration on zooplankton community in a permanent interdunal pond

2013

Restoration projects in wetlands are becoming increasingly frequent to recover or to create new aquatic ecosystems, after the significant impact and high degradation they have undergone. In the present study, we focused on the changes in the zooplankton community in a permanent peridunal pond where a restoration was carried out in order to increase its surface as a main objective. For this purpose, the community was compared before and after the restoration (15 years before, the year after and between 3 and 6 years later). Significant changes in environmental variables were observed after pond restoration: chlorophyll a concentration decreased and dissolved oxygen increased. Substantial mod…