Crowdsourcing a cyclist perspective on suggested recreational paths in real-world networks

ABSTRACT

Routing and navigation services for leisure activities are conditioned by special needs and trade-offs. The advent of online communities and large crowdsourced datasets offers opportunities to improve the adoption of a user’s perspective in these suggested paths. This paper focuses on achieving two goals. First, the presented methodology analyses a dataset of 190,610 historical GPS traces to gain insights into the appreciation or attractiveness of each edge in a real-world network for a specific leisure activity (i.e. road cycling). Second, as literature on these leisure activities is still sparse, we want to create a thorough understanding of the activities at hand for future work. An appreciation model is proposed and the spread of this score is analyzed in shortest-path alternatives of popular routing engines for this activity. This analysis successfully discriminates these shortest paths based on the scoring value and three morphological parameters of the path. However, the robustness of the model should be improved to ensure the viability of the proposed approach in future work. More specifically, further research on the local optimality of the route choices will be imperative.     

Recent trends in annual snowline variations in the northern wet outer tropics: case studies from southern Cordillera Blanca,Peru

TL-moments approach has been used in an analysis to identify the best-fitting distributions to represent the annual series of maximum streamflow data over seven stations in Johor, Malaysia. The TL-moments with different trimming values are used to estimate the parameter of the selected distributions namely: Three-parameter lognormal (LN3) and Pearson Type III (P3) distribution. The main objective of this study is to derive the TL-moments (t ₁,0), t ₁?=?1,2,3,4 methods for LN3 and P3 distributions. The performance of TL-moments (t ₁,0), t ₁?=?1,2,3,4 was compared with L-moments through Monte Carlo simulation and streamflow data over a station in Johor, Malaysia. The absolute error is used to test the influence of TL-moments methods on estimated probability distribution functions. From the cases in this study, the results show that TL-moments with four trimmed smallest values from the conceptual sample (TL-moments [4, 0]) of LN3 distribution was the most appropriate in most of the stations of the annual maximum streamflow series in Johor, Malaysia.     

Actor-Based Design of a Management System for the Elephant Marsh Fishery in Malawi

In Malawi, fishing community user groups known as beach village committees, traditional chiefs, government officers, and fishers are the key players in fisheries management. Fish catch trends at the Elephant Marsh Fishery in southern Malawi are declining. Based on interviews and participant observation, this article uses an actor-based framework (known as Action-in-Context) to unveil the issues that are crucial in devising a sustainable governance system for the fishery. We establish and propose that the key social variables for the design of a three-pillared (locally based, weak, and amorphous) resilient institution for sustainability of the Elephant Marsh Fishery are (i) the social reputation of the leaders of local fishery institutions (beach village committee leaders), and (ii) the power dynamics between traditional chiefs and these local fishery leaders. We end the article by exploring the implications of the findings on the sustainability of the fishery under rising resource pressure.     

A record of the Messinian salinity crisis in the eastern Ionian tectonically active domain (Greece,eastern Mediterranean)

This integrated study (field observations, micropalaeontology, magnetostratigraphy, geochemistry, borehole data and seismic profiles) of the Messinian–Zanclean deposits on Zakynthos Island (Ionian Sea) focuses on the sedimentary succession recording the pre‐evaporitic phase of the Messinian salinity crisis (MSC) through the re‐establishment of the marine conditions in a transitional area between the eastern and the western Mediterranean. Two intervals are distinguished through the palaeoenvironmental reconstruction of the pre‐evaporitic Messinian in Kalamaki: (a) 6.45–6.122 Ma and (b) 6.122–5.97 Ma. Both the planktonic foraminifer and the fish assemblages indicate a cooling phase punctuated by hypersalinity episodes at around 6.05 Ma. Two evaporite units are recognized and associated with the tectonic evolution of the Kalamaki–Argassi area. The Primary Lower Gypsum (PLG) unit was deposited during the first MSC stage (5.971–5.60 Ma) in late‐Messinian marginal basins within the pre‐Apulian foreland basin and in the wedge‐top (<300 m) developed over the Ionian zone. During the second MSC stage (5.60–5.55 Ma), the PLG evaporites were deeply eroded in the forebulge–backbulge and the wedge‐top areas, and supplied the foreland basin's depocentre with gypsum turbidites assigned to the Resedimented Lower Gypsum (RLG) unit. In this study, we propose a simple model for the Neogene–Pliocene continental foreland‐directed migration of the Hellenide thrusting, which explains the palaeogeography of the Zakynthos basin. The diapiric movements of the Ionian Triassic evaporites regulated the configuration and the overall subsidence of the foreland basin and, therefore, the MSC expression in this area.     

Alonso's Theory of Movements: Developments in Spatial Interaction Modeling

 The Spatial Interaction Model proposed by Alonso as “Theory of Movements” offers an innovative specification of spatial origin-destination flow models. Equations for flows between regions, total outflow from and total inflow to a region are linked by balancing factors. This paper presents a consistent formulation of Spatial Interaction Models in the Wilson tradition and Alonso's Theory of Movements. The paper is intended as an introduction to the model and a review of␣the state of the art. Besides it is argued that simultaneous equation techniques are required to estimate the so-called systemic parameters. Received: 21 May 2000 / Accepted: 18 January 2001     

MERIS and the red-edge position

The Medium Resolution Imaging Spectrometer (MERIS) is a payload component of Envisat-1. MERIS will be operated over land with a standard 15 band setting acquiring images with a 300 m spatial resolution. The red-edge position (REP) is a promising variable for deriving foliar chlorophyll concentration, which plays an important role in ecosystem processes. The objectives of this paper are: (1) to study which factors effect the REP of vegetation, (2) to study whether this REP can be derived from the MERIS standard band setting and (3) to show what REP represents at the scale of MERIS data. Two different data sets were explored for simulating the REP using MERIS bands: (1) simulated data using reflectance models and (2) airborne reflectance spectra of an agricultural area obtained by the airborne visible-infrared imaging spectrometer (AVIRIS). A “linear method”, assuming a straight slope of the reflectance spectrum around the midpoint of the slope, was a robust method for determining the REP and the MERIS bands at 665, 708.75, 753.75 and 778.75 nm could be used for applying the “linear method” for REP estimation. Results of the translation to the scale of MERIS data were very promising for applying MERIS at, for instance, the ecosystem level.     

Eclogitic metasediments from the Tso Morari area (Ladakh, Himalaya): evidence for continental subduction during India-Asia convergence

Metasediments in the Tso Morari area (Ladakh, Himalaya) provide new insights into the Higher Himalayan metamorphism in the northwestern part of the Himalayan belt. Whole-rock analyses and petrologic observations show that the metasediments correspond to Fe-rich metapelites, Mg-rich metapelites, intermediate metapelites and metagreywackes of the Indian continental margin. Jadeite + chloritoid + paragonite + garnet in the Fe-rich metapelites indicate pressures of 20 ±2 kbar at temperatures of 550 ±50 °C according to major element partitioning thermobarometry, stability fields of minerals and Thermocalc P-T estimates. These results are consistent with P-T estimates on other metasediments and with the occurrence of eclogites. Subsequent retrogression at the eclogite-blueschist facies transition (from 18 to 13 kbar and 540 ±50 °C) was followed by an increase in temperature to 630 ±30 °C at amphibolite facies conditions. The metamorphic evolution is related to subduction of the Indian continental margin beneath the southern Asian margin at the onset of the Indian-Eurasian collision. Received: 17 April 1996 / Accepted: 19 February 1997     

Mobility of rare-earth elements and copper during shear-zone-related retrograde metamorphism

In Mid Proterozoic crystalline rocks of the Mount Isa Inlier, around Cloncurry, Australia, 2000 km² of alteration and brecciation are the product of high-temperature (> 450 °C) concentrated saline solution activity. During retrogression, this fluid was locally responsible for mobility of V, Y, Nb and light rare-earth elements (15 × enrichment). Copper and S were leached during alteration and this may have been a significant source of components in nearby Cu-Au deposits. Similar rare-earth-element behaviour has been observed in the hematite breccias which host Cu-sulfides at the giant Olympic Dam Cu-Au deposit.     

Sesquiterpenoids in sediments of a hypersaline lagoon: A possible algal origin

Core samples were collected in Lagoa Vermelha, a hypersaline lagoon located about 100 km east of Rio de Janeiro (Brazil). The sediment composition is predominantly carbonate in amounts up to 93%. Analysis of δ¹³C of the total organic matter in the sediments showed that marine organic matter predominates throughout the core (δ¹³C ranges from −15.84 to −22.64‰ vs. PDB). Organic carbon contents (TOC) ranged from 0.81 to 13.28%. A series of cadinane-type sesquiterpenoids can be recognized in the gas chromatography-mass spectrometry data. Essentially the same components are present in all the samples, with variations only in their relative abundances. The most abundant compounds are α- and β-cubebene, α- and β-cedrene, cadinenes (different isomers), α-curcumene and calamenene, with minor amounts of calarene, humulene, calacorene and cadalene. Since this lagoon is surrounded by dunes with only minor vegetation typical of this environment (grasses, small non-resinous shrubs and no forest) with no potential source for sesquiterpenoids, a terrestrial origin for these compounds is excluded and an algal origin is more consistent with the locale and the recognition of sesquiterpenoids (including cadinol) in microbial mats from the lagoon. Only the natural product precursor sesquiterpenoids are present in the microbial mats with no detectable diagenetic derivatives (e.g. calamenene and cadalene). This indicates that the compounds in the mats are from recent input and those found in the sediments are most likely derived from former algal biomass in this lagoon, a fact confirmed by the recognition of a series of diagenetic aromatic components in the sediments. Surface sediments contain n-alkanes with no even-to-odd predominance indicating that microbial activity is higher in shallower sediments. Moreover, mass fragmentograms (m/z 191) of biomarkers revealed the presence of 17α(H),21β(H)-hopanes, the mature isomers, together with their ββ precursors and low amounts of the intermediates with the βα configuration (moretanes). This indicates a contribution of mature organic matter to these immature sediments.