Multi‐temporal transport network models for accessibility studies

Vehicle tracking is a spatio‐temporal source of high‐granularity travel time information that can be used for transportation planning. However, it is still a challenge to combine data from heterogeneous sources into a dynamic transport network, while allowing for network modifications over time. This article uses conceptual modeling to develop multi‐temporal transport networks in geographic information systems (GIS) for accessibility studies. The proposed multi‐temporal network enables accessibility studies with different temporal granularities and from any location inside the city, resulting in a flexible tool for transport and urban planning. The implemented network is tested in two case studies that focus on socially excluded people in a large global city, São Paulo, Brazil, including accessibility analyses from slum areas. It explores variations within a day and differences between transport modes across time. Case study results indicate how the accessibility is heterogeneous in low‐income regions.     

Vertical distribution of two sympatric labrid fishes in the Western Mediterranean and Eastern Atlantic rocky subtidal: local shore topography does matter

Changes in the shore topography (e.g. slope) occur at a scale of hundreds of meters in several locations in the Lusitanian and the Mediterranean Sea provinces. We tested whether differences in the bottom inclination might affect the vertical distribution patterns of two sympatric coastal labrid fishes, the rainbow wrasse Coris julis and the ornate wrasse Thalassoma pavo. Visual censuses were used to determine the distribution and abundance of these labrid species in high (≥30°) and low (≤3°) slope rocky substrates covered by brown macroalgae and at two different depths (shallow, 4–7 m, and deep 14–20 m). Pectoral fin aspect ratio was used as an estimate of swimming performance to potentially explain the patterns observed. Despite the intrinsic biogeographical differences in the overall density of T. pavo and C. julis, on steep coasts the ornate wrasse dominated in shallow waters, whereas the two species coexisted both in shallow and deeper depths on gentle slope coasts. These distribution patterns were consistent across locations, and fin aspect ratio was not a good predictor of between‐habitat use for wrasses. We show that, under specific topographical conditions, the depth segregation pattern seems to be an interactive segregation (likely related to resource competition) rather than a result of selective segregation due to morphological differences in the pectoral fin. Significant ecological changes might occur in locations where the density of T. pavo has recently increased as a result of water warming.     

Impact area determination of pyroclastic deposits in Lascar volcano, eruptive process in the year 1993

By means of multi-temporal analysis of satellite images and statistical algorithms, the amount of pyroclastic material deposited on Lascar volcano walls after the gravitational collapse of the eruptive column caused by the eruption that occurred on April the 19th and the 20th in 1993 was determined and quantified. For this analysis, scenes corresponding to Landsat 4 TM in 1989 and Landsat 7 ETM+ in 2001 were used. By careful selection methods such as combination of bands, unsupervised classification, and the Karhunen–Loève transform, detailed analysis of zones of change that correspond to pyroclastic deposits were made. This analysis was complemented with in situ data in order to correct and calibrate the satellite images to identify zones of 1993s eruption pyroclastic deposits. Using Kittler’s and other thresholding algorithms, a search was performed for a proper threshold to binarize the images to determine the surface area covered by the eruptive process. Matlab™ software was used both for general programming and for digital image processing.     

Environmental-economic evaluation of the filling and reclamation process in the bay of Santander,Spain

The historical development of a process of reclamation of intertidal areas in an estuary has been quantitatively studied by means of old engravings, maps, navagation charts, and aerial photographs. These show that about 83 percent of the natural coastline of the estuary has disappeared, nearly two-thirds of its intertidal area has been covered, and over 40 percent of its volume has been lost. The rate of this artificial process is several tens of times faster than that of the natural sedimentation. Extrapolation of the observed trends shows that, if these continue, the intertidal areas would disappear completely in 31 to 105 years. Theoretical calculations based on comparisons with other estuaries show that the accumulated loss in the productivity of living matter (in the form of primary producers), since the process started about 140 years ago, could reach 1.5·10¹⁰ kg. This could represent, considering several possible food chains, the equivalent of the food necessary to sustain several thousand people for life. An economic analysis of the impact of the process has been made by considering, first, the decrease in fish and shellfish catches in the bay (using historical data and data about present clam productivity) and the decrease in its aesthetic quality and recreational potential. These were determined by means of interviews with the population to obtain a “demand curve” for the willingness to pay for the preservation and use of the bay. Second, the price of the man-made land obtained was considered. The data obtained show that the economic losses would offset the benefits within 10 to 30 years.     

Shear and dilatational wave velocities for unsaturated soils

The primary objective of this study is for presenting some simple-to-use expressions relating the shear and dilatational wave velocities (V_S and V_P) to some physical and constitutive parameters of unsaturated soils. To this purpose, a simplified formulation is developed using the theory of linear poroelasticity in conjunction with some constitutive parameters widely used in geotechnical engineering. The derived expressions are of practical interest in view of the fact that they could be employed for evaluating the involved soil parameters from V_S and V_P measurements by in-situ or laboratory geophysical tests.     

Sources and Distribution of Particulate Organic Matter of a Tropical Estuarine-Lagoon System from NE Brazil as Indicated by Lipid Biomarkers

In the present work, we evaluated the origin of organic matter in the tropical estuarine-lagoon system of Mundaú–Manguaba, NE Brazil, by considering the bulk (organic carbon and chlorophyll-a) and lipidic (n-alcohols and sterols) composition of suspended particles. Water samples were collected in August 2006 from 24 stations covering the salinity gradient from the rivers down to the sea outlet. Chlorophyll-a (Chl-a) varied from 22.7 to 134.1 μg L⁻¹ in the lagoons, indicating eutrophic to hypertrophic conditions at the time of sampling. The high correlation between Chl-a and phytol together with the molar C:N ratio indicated the presence of fresh and recently produced autochthonous particulate organic matter throughout the system, except for the river samples. The elevated concentrations of short-chain n-alcohols and phytosterols, mainly 24-methylcholesta-5,24(28)-dien-3β-ol, also corroborated the predominance of autochthonous organic matter in the lagoons but were generated by distinct sources: cianobacteria in the freshwater Manguaba lagoon and diatoms in the brackish Mundaú lagoon compartments. Input of terrestrial organic matter was only detected in the rivers themselves or at the upper river–lagoon interfaces. Coprostanol indicated contamination by sewage in Mundaú lagoon and in some rivers, but at lower levels when compared to other Brazilian coastal lagoons and estuaries.     

Investigation of the carrageenans extracted from Solieria filiformis and Agardhiella subulata from Mar Piccolo, Taranto

Dried samples of the red algae Solieria filiformis and Agardhiella subulata from Mar Piccolo, Taranto, were extracted by stirring in water at 25 (Cold), 85 (Hot) and 120 (pressure) °C. For each species, six successive cold, three hot and two pressure extractions were performed and analyzed separately. Water-soluble polysaccharides were isolated after treatment with amylase, alcohol precipitation, dialysis and freeze drying. The total, starch-free yields were 27 and 24% of the dry weight for S. filiformis (SF) and A. subulata (AS), respectively. FTIR and NMR spectroscopic analysis showed that the different cold and hot water extracts had a similar structural backbone, which can be characteristic of gelling type carrageenans with a dominant iota repeating structure (DA2S-G4S). However, some irregularities were detected by NMR, which may be attributed to 6-sulphated 4-linked precursor units. The occurrence of such and other irregularities was more frequent in the SF samples, giving a possible explanation for the enhanced extractability in cold water of carrageenan polymers from this species.     

Long-range dependence in the runoff time series of the most important Patagonian river draining to the Pacific Ocean

The Baker River is the largest free-flowing river in Chilean Patagonia. Long-range dependence (LRD), a recognised hydrological property of river runoff worldwide, was detected for the Baker River runoff time series. Analyses were conducted on a monthly scale between 1961 and 2015 using the fractal and multifractal detrended fluctuation analysis methodology. A long-range-dependent Hurst coefficient (H) equal to 0.94 was obtained. A scaling range, which is the signature of LRD, was detected for the Baker River runoff time series between 1 and 5.25 years. Baker River runoff showed a strong correlation (r?=?0.96) with the Antarctic Oscillation (AAO) Index during the 2007–2015 period. The high storage capacity of Lake General Carrera, the size of the Baker River basin area and the dynamics of AAO are proposed as main factors that contribute to the emergence of LRD in the Baker River runoff time series.     

A field‐scale infiltration model accounting for spatial heterogeneity of rainfall and soil saturated hydraulic conductivity

This study first explores the role of spatial heterogeneity, in both the saturated hydraulic conductivity K_s and rainfall intensity r, on the integrated hydrological response of a natural slope. On this basis, a mathematical model for estimating the expected areal‐average infiltration is then formulated. Both K_s and r are considered as random variables with assessed probability density functions. The model relies upon a semi‐analytical component, which describes the directly infiltrated rainfall, and an empirical component, which accounts further for the infiltration of surface water running downslope into pervious soils (the run‐on effect). Monte Carlo simulations over a clay loam soil and a sandy loam soil were performed for constructing the ensemble averages of field‐scale infiltration used for model validation. The model produced very accurate estimates of the expected field‐scale infiltration rate, as well as of the outflow generated by significant rainfall events. Furthermore, the two model components were found to interact appropriately for different weights of the two infiltration mechanisms involved. Copyright © 2005 John Wiley & Sons, Ltd.     

RR Lyrae pulsational temperature scales: on the consistency between different empirical relations

In this paper, by assuming the equilibrium temperatures of RRab Lyrae variables defined by Carney, Storm & Jones as correct we show that temperatures derived from ( B − V ) colour (mean colour over the pulsational cycle calculated on the magnitude scale) transformations by Bessel, Castelli & Plez are consistent with the Carney et al. equilibrium temperatures within a probable error of δ  log  T _e =±0.003 . As a consequence, it is shown that the pulsational temperature scale temperature–period–blue amplitude [ T _eff= f ( P , A _B )] relation provided by De Santis, who studied the ( B − V ) colour of about 70 stars of Lub's sample, is a suitable relation, being reddening- and metallicity-free, to calculate equilibrium temperatures for RRab variables. This relation is independent of variable mass and luminosity within a large range of period-shift from the mean period–amplitude relation valid for Lub's sample of variables. On the contrary, it is also shown that a temperature–amplitude–metallicity relation is strictly dependent on the period–amplitude relation of the sample used for calibrating it: we prove that this means it is dependent on both the mass and luminosity variations of variables.