Seasonal to interannual variability of satellite derived chlorophyll‐a over the Patagonia shelf and shelf break in the western South Atlantic are studied based on 7 years of ocean‐color data ...(1998–2004) from the Sea‐Viewing Wide Field‐of‐View Sensor (SeaWiFS). Strong chlorophyll‐a seasonal variability (>4 mg m−3) is observed compared to the open ocean (<1.5 mg m−3). North of 45°S, chlorophyll‐a blooms initiate in early austral spring (September and October), while south of 45°S blooms begin in late spring to early summer (November through January). The spring maximum (>3.5 mg m−3) extends from the midshelf to the shelf break between 37°S and 44°S and southward to 51°S along a narrow shelf break band. In summer the shelf break maximum persists from 37°S to 51°S, and two inner‐shelf blooms develop off Valdés Peninsula and along a near‐coastal band between 46°S and 52°S (>3 mg m−3). Chlorophyll‐a concentrations in the northern midshelf sharply decay in late spring, reaching lowest concentrations in summer (February and March) and a secondary maximum in early winter (June). Though all regions present substantial interannual variations, the bloom locations are stable. The shelf break maximum is located inshore of the front between the low salinity shelf waters and the cold, salty, and nutrient‐rich Malvinas Current waters. The inner shelf maxima are offshore of fronts separating well‐mixed coastal waters from the stratified midshelf. North of 41°S the midshelf bloom is also associated to a bottom trapped thermal front. Thus, all the high chlorophyll‐a regions are associated to well‐defined fronts.
•This paper analyses the vulnerability and criticality of a public transport network.•We calculate the impact of each link in the network on travel times using a full scan approach implemented in ...GIS.•We analyse the role of circular lines regarding network vulnerability.•The more critical scenarios are identified in a sequence of link disruptions, simulating a targeted attack.•The case study used is the subway network in the city of Madrid.
In the last years, studies on the vulnerability of public transport networks attract a growing attention because of the repercussions that incidents can have on the day-to-day functioning of a city. The aim of this paper is to develop a methodology for measuring public transport network vulnerability taking the Madrid Metro system as an example. The consequences of a disruptions of riding times or the number of missed trips are analysed for each of the network links with a full scan approach implemented in GIS (Geographic Information Systems). Using real trips distribution, each link in the network is measured for criticality, from which the vulnerability of lines and stations can be calculated. The proposed methodology also makes it possible to analyse the role of circular lines in network vulnerability and to obtain a worst-case scenario for the successive disruption of links by simulating a targeted attack on the network. Results show the presence of critical links in the southern part of the network, where line density is low and ridership high. They also highlight the importance of the circular line as an element of network robustness.
Comparing the covariation patterns of populations or species is a basic step in the evolutionary analysis of quantitative traits. Here I propose a new, simple method to make this comparison in two ...population samples that is based on comparing the variance explained in each sample by the eigenvectors of its own covariance matrix with that explained by the covariance matrix eigenvectors of the other sample. The rationale of this procedure is that the matrix eigenvectors of two similar samples would explain similar amounts of variance in the two samples. I use computer simulation and morphological covariance matrices from the two morphs in a marine snail hybrid zone to show how the proposed procedure can be used to measure the contribution of the matrices orientation and shape to the overall differentiation.
I show how this procedure can detect even modest differences between matrices calculated with moderately sized samples, and how it can be used as the basis for more detailed analyses of the nature of these differences.
The new procedure constitutes a useful resource for the comparison of covariance matrices. It could fill the gap between procedures resulting in a single, overall measure of differentiation, and analytical methods based on multiple model comparison not providing such a measure.
New efforts in the search of alternative clean and renewable energy to replace the current energy precursors have been assessed in order to reduce emissions to the environment. Lignocellulosic ...Biomass (LB) can be used to produce bioenergy due to its high energy potential and availability. Different ways are proposed for the transformation of these residues into high added-value products. Thermochemical and biochemical technologies are the most interest concepts focusing on the use of biomass as source for energy production at positive net balances. This study presents the techno-economic, energy and environmental assessment of five scenarios for the hydrogen production through gasification and dark fermentation based on the biorefinery and stand-alone concepts. The results demonstrated that the production of hydrogen based on the concept of a biorefinery can improve the profitability, energy efficiency and reduce the emissions of the processes compared to that based on the stand-alone way. The selection of ethanol and electricity as valuable co-products of the biorefinery in the hydrogen production process confirmed that the process scale and products diversity makes possible a flexible and suitable process to produce hydrogen and other energy carriers from Pinus Patula.
•Production of hydrogen under the concept of biorefinery enhances the process profitability.•The scale of the process is a key factor of the process flexibility and performance.•The hierarchy of the products can modify the behavior of the hydrogen production cost.
This paper presents a flexible ultraviolet (UV) photodetector (PD) system based on zinc oxide (ZnO) nanowires (NWs) for wearable UV dosimetry. High-crystal quality ZnO NWs have been synthesized by ...chemical vapour transport technique on c-plane sapphire substrates, and thereafter, transferred and aligned at pre-defined locations on a flexible substrate using dielectrophoresis (DEP). The accurate control over DEP parameters permitted the fabrication of large-area (wafer scale) arrays of ZnO NWs-based UV PDs. Resulting PDs showed photocurrent-to-dark current ratios above 10 3 %, fast response times (<;1 s), high sensitivity to different UV light intensities, and good stability under several UV/dark irradiation cycles. In addition, above PDs presented a robust response under extreme bending conditions, which is critical for their application in high-performance wearable UV dosimeters.
Structural instabilities can be used to provide rapid responses activated by mechanical force or displacement thresholds. The emergence of responsive materials has opened the door for adapting such ...structural instabilities to actuators that will abruptly deform guided by external stimuli. However, fast configurational transitions between equilibrium states imply important viscoelastic roles at the material level that inevitably scale up to the structural level. A comprehensive understanding of viscoelastic effects is provided on bistable structural transitions combining a new experimental perspective and a thorough modeling analysis. The insights from these results are here translated to magneto‐responsive bistable structures offering a route‐map to design effective actuation conditions. The bistable transition functionally depends on the combination of magnetic field amplitude and application rate. The understanding of the viscoelastic and magneto‐mechanical coupling provides efficient actuation via temporal magnetic pulses, removing the need of generating continued magnetic fields. Finally, these insights are combined to develop a responsive structure whose transient and steady bistable transitions can be modulated by the application rate of external magnetic stimuli.
Viscoelastic mechanisms are demonstrated valuable designing variables to conceptualize bistable structures with rate‐dependent actuation modes. The viscoelastic response of beam components is simulated by an original constitutive beam‐element formulation. Based on these viscoelastic insights, magneto‐responsive structural components are developed. The transient and steady bistable transitions of these structures can be modulated by the application rate of external magnetic stimuli.
There is little knowledge available on the spatial behaviour of urban tourists, and yet tourists generate an enormous quantity of data when they visit cities. These data sources can be used to track ...their presence through their activities. The aim of this paper is to analyse the digital footprint of urban tourists through Big Data. Unlike other papers that use a single data source, this article examines three sources of data to reflect different tourism activities in cities: Panoramio (sightseeing), Foursquare (consumption), and Twitter (being connected-accommodation). The results show that the data from the three activities are partly spatially redundant and partly complementary, and allow the characterisation of multifunction tourist spaces and spaces specialising in one or various activities. The main conclusion is that it is not sufficient to use one data source to analyse the presence of tourists in cities; several must be used in a complementary manner.
•The paper analyses the digital footprint of urban tourists through Big Data.•Panoramio, Foursquare and Twitter reflect different tourism activities.•The methods used are density maps, OLS, spatial self-correlation and cluster analysis.•The results show different tourist spaces: multifunction (several activities) vs specialising.
Idiopathic noncirrhotic portal hypertension is a heterogeneous group of diseases characterized by portal hypertension in the absence of cirrhosis. The efficacy and safety of transjugular intrahepatic ...portosystemic shunt (TIPS) in this population are unknown. The charts of patients with idiopathic noncirrhotic portal hypertension undergoing TIPS in seven centers between 2000 and 2014 were retrospectively reviewed. Forty‐one patients were included. Indications for TIPS were recurrent variceal bleeding (n = 25) and refractory ascites (n = 16). Patients were categorized according to the presence (n = 27) or absence (n = 14) of significant extrahepatic comorbidities. Associated conditions were hematologic, prothrombotic, neoplastic, immune, and exposure to toxins. During follow‐up (mean 27 ± 29 months), variceal rebleeding occurred in 7/25 (28%), including three with early thrombosis of the stent. Post‐TIPS overt hepatic encephalopathy was present in 14 patients (34%). Eleven patients died, five due the liver disease or complications of the procedure and six because of the associated comorbidities. The procedure was complicated by hemoperitoneum in four patients (10%), which was fatal in one case. Serum creatinine (P = 0.005), ascites as indication for TIPS (P = 0.04), and the presence of significant comorbidities (P = 0.01) at the time of the procedure were associated with death. Mortality was higher in patients with significant comorbidities and creatinine ≥100 μmol/L (P < 0.001). Conclusion: In patients with idiopathic noncirrhotic portal hypertension who have normal kidney function or do not have severe extrahepatic conditions, TIPS is an excellent option to treat severe complications of portal hypertension. (Hepatology 2016;64:224–231)
New sources of geolocated information, associated with big data and social networks, show great promise for geographical research, especially in the field of tourism geography. Photo-sharing services ...comprise one of these sources. The aim of this article is to demonstrate the potential of photo-sharing services for identifying and analyzing the main tourist attractions in eight major European cities: Athens, Barcelona, Berlin, London, Madrid, Paris, Rome and Rotterdam. Geotagged photographs on Panoramio were differentiated according to whether they had been taken by tourists or local residents, and their spatial distribution patterns were analyzed using spatial statistical techniques in a GIS. The results indicated the concentration and dispersion of photographs in each city and their main hot spots, and revealed marked differences between tourists' and residents' photographs, since the former showed higher spatial concentrations. In addition, differences were observed between cities; Barcelona and Rome presented a strong spatial concentration compared with London or Paris, which showed much greater dispersion.
•Big data and social networks provide great opportunities for geographical research.•We examine the potential of photo-sharing services for urban tourism studies.•We differentiate geotagged photos taken by tourists or locals.•We analyze eight major European cities using spatial statistical techniques and GIS.•Distribution patterns affect tourism management and potential visitors.
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