Climate change and cetacean health : impacts and future directions

Acknowledgments We would like to thank Dr Jo Kershaw for paper recommendations and insightful comments. We would also like to thank two anonymous reviewers for very helpful feedback on the manuscript that helped improve it.Peer reviewedPostprin

Intra-population variation in isotopic niche in herring-eating killer whales off Iceland

Among-individual variation in dietary preferences can impact community dynamics and be a driving force for evolutionary divergence, although it can be difficult to assess in free-ranging marine mammal populations. In this study, we investigate the existence of variation in isotopic niche within a population of putative herring-specialist killer whales. Isotopic ratios of carbon and nitrogen were measured in 67 skin biopsy samples from 56 individual killer whales, sampled in herring overwintering (winter) grounds and spawning (summer) grounds in Iceland when the whales were presumably feeding on herring. Whales that appeared to follow herring year round (n = 31) had lower δ15N values, consistent with a diet predominantly composed of herring. This supports the existence of herring specialists in the population. In contrast, whales that were only photo-identified either in winter or in summer (n = 25) had larger variation in δ15N values. A discriminant function analysis clearly distinguished between putative herring specialists and whales seasonally travelling to Scotland in summer (n = 3), which exhibited distinctly larger δ15N values indicative of a diet including higher trophic level prey. This study shows that herring-eating killer whales in Iceland exhibit intra-population ecological variation, whereby individuals or groups differ in the proportional contribution of different prey items to their diet. This variation occurs in the absence of social and, potentially, reproductive isolation. Although further information will be required to assess the degree of structuring within the population, such heterogeneity should be taken into account in future conservation and management plans

Pilot whales attracted to killer whales sounds : acoustically-mediated interspecific interactions in cetaceans

This study was mainly funded by three naval organisations: the US Office of Naval Research, the Norwegian Ministry of Defense and the Netherlands Ministry of Defense. In addition, WWF-Norway, TOTAL Foundation and the Foundation Bleustein-Blanchet also contributed financially. Authors are employed by government (Norwegian Defense Research Establishment), independent no-profit (Netherlands Organization for Applied Scientific Research and Kelp Marine Research), or academic (University of St. Andrews) research organisations. No authors are employed by naval organisations. The funders had no role in study design, data analysis, or preparation of the manuscript.In cetaceans’ communities, interactions between individuals of different species are often observed in the wild. Yet, due to methodological and technical challenges very little is known about the mediation of these interactions and their effect on cetaceans’ behavior. Killer whales (Orcinus orca) are a highly vocal species and can be both food competitors and potential predators of many other cetaceans. Thus, the interception of their vocalizations by unintended cetacean receivers may be particularly important in mediating interspecific interactions. To address this hypothesis, we conducted playbacks of killer whale vocalizations recorded during herring-feeding activity to free-ranging long-finned pilot whales (Globicephala melas). Using a multi-sensor tag, we were able to track the whales and to monitor changes of their movements and social behavior in response to the playbacks. We demonstrated that the playback of killer whale sounds to pilot whales induced a clear increase in group size and a strong attraction of the animals towards the sound source. These findings provide the first experimental evidence that the interception of heterospecific vocalizations can mediate interactions between different cetacean species in previously unrecognized ways.Publisher PDFPeer reviewe

Relevância da gestão da informação e dos sistemas de informação no Cluster do Turismo, enquanto recursos estratégicos e forma de Branding. Estudo de caso às unidades hoteleiras

O turismo como indústria de serviços, com um alcance internacional através de redes, que possui especificidades únicas como a sua heterogeneidade, intangibilidade e perecibilidade, que o diferenciam dos restantes produtos, exige uma elevada mobilização de informação. É daqui que sobressai a relevância dos sistemas de informação como recursos estratégicos, apoiados em informação, processos e tecnologias, sendo inquestionável a afirmação de que os mesmos se transformaram num dos fatores determinantes da competitividade do setor do turismo. A presente dissertação constitui uma análise e reflexão crítica na abordagem da utilização dos sistemas de informação na área de atividade económica do turismo, enquanto elementos críticos para a prossecução de estratégias de organização, para alcançar, ativar e integrar stakeholders dispersos territorialmente. A abordagem assenta na interpretação da importância da informação e da sua gestão para o funcionamento interno e externo do cluster, através das formas como mobiliza agentes económicos dos vários stakeholders, produzindo elementos de branding. O principal contributo do trabalho concretiza-se na sistematização de um exercício que justifica de forma sustentada a relevância da gestão da informação e dos sistemas de informação para o desenvolvimento da indústria do turismo, pelo que se procedeu a uma revisão do estado da arte sobre a problemática da investigação, tendo como base os conceitos chave definidos. Por último, o trabalho foi ainda suportado por um processo de recolha e análise de dados que sustentou o desenvolvimento de uma investigação metodológica; Relevance of information management and information systems in the tourism cluster, as strategic resources and form of branding. Case study in hotel units. Abstract: Tourism as a service industry, has an international range via networks that possesses unique features - heterogeneity, unattainability and perishability. That differentiates it from all the other products. Thus requiring a high mobilization of information. This stands out the importance of systems of information as strategical resources supported by information, processes and technologies and, without doubt, the affirmation that the same are changed in one of the most important basis of competitiveness in the tourism area. This thesis is an analysis and critical reflection in the approach to the use of information systems in the economic area of tourism, as critical elements for the pursuit of organizational strategies, to reach, to activate and to integrate stakeholders dispersed territorially. The approach is based on the interpretation of importance of information and its management for the internal and external functioning of the cluster, through the ways in which it mobilizes economic agents from the various stakeholders, producing branding element’s. The main contribution of the work is to systematize an exercise that justifies the relevance of information management and information systems for the development of the tourism industry, supported on the necessary bibliographic revision of the research problem, based on the key concepts defined. Finally, the work was also supported by a data collection and analysis process that supported the development of a methodological investigation

Estudi de la hipòtesi de Riemann: nombres primers i aplicacions

En aquest treball s’estudia la hipòtesi de Riemann, un problema matemàtic relacionat amb la distribució dels nombres primers i que no ha estat resolt des que el 1859, Bernhard Riemann, un matemàtic alemany, l’anuncià en una memòria escrita de menys de 10 pàgines. Aquesta hipòtesi forma part del selecte grup dels Problemes del mil·lenni, i s’ofereixen 1.000.000 de dòlars a qui pugui verificar-la o negar-la. En aquest treball es pretén arribar a comprendre com fou plantejada la hipòtesi i en quines circumstàncies, per això s’estudien treballs d’altres matemàtics com ara Gauss o Euler, ja que les seves publicacions contribuïren a què Riemann finalment formulés la famosa hipòtesi, i foren molt importants, ja que sense les aportacions de diversos matemàtics a aquesta ciència, probablement no s’hauria pogut formular la hipòtesi. Moltíssims matemàtics al llarg de la història han intentat trobar una fórmula màgica que generi tots els nombres primers, o vàries fórmules que entre elles els cobreixin tots, però donat que això no fou possible, Gauss començà estudiant la distribució dels nombres primers, doncs no aconseguia trobar-hi un sentit complet, i a partir d’aquí definí una funció que comptaria els nombres primers, i la representació gràfica d’aquesta seria com una escala infinita. A partir d’aquí, molts matemàtics intentaren trobar una funció que seguís per complet el comportament de la funció �(�) que definí Gauss, i a partir d’estudis diversos d’altres matemàtics, hi acabaren intervenint els nombres complexos. A partir d’aquí s’obrí un nou camí que il·luminaria esperances perdudes als matemàtics que ja havien perdut l’esperança respecte la distribució dels nombres primers. Les relacions que Riemann feu amb els matemàtics que intervindran en aquesta història foren clau, doncs tot plegat resulta irònicament com una recepta d’ingredients aparentment independents que entrellaçats donen lloc a un plat deliciós Per a poder realitzar aquest treball s’ha seguit l’article de Don Zagier, The first 50 million prime numbers. També s’ha seguit el llibre de Marcus Du Sautoy, La música de los números primos, títol que sorgeix gràcies a la relació d’aquesta hipòtesi amb la sèrie harmònica, i altres articles que també tracten la hipòtesi de Riemann. S’ha emprat l’eina Maple per a poder representar gràficament les funcions que hi intervenen i poder realitzar càlculs complicats

Persistence of skin marks on killer whales (Orcinus orca) caused by the parasitic sea lamprey (Petromyzon marinus) in Iceland

Lampreys have long been thought to be a cetacean ectoparasite, due to the observation of round marks on the skin of whales caught during whaling operations. Pike (1951), Nemoto (1955), and van Utrecht (1959) compared such marks on the skin of various cetacean species caught in the Pacific and Atlantic Oceans with the dentition of lampreys and concluded that most round marks had been caused by this parasite. However, lampreys were never collected from captured whales and, due to the lack of direct evidence, some discussion emerged as to the origin of these wounds. Jones (1971) later argued that crescent-shaped marks previously attributed to lampreys were in fact caused by cookie-cutter sharks (Isistius brasiliensis). However, he agreed that other round marks were undoubtedly caused by lampreys. Recently, photographs of sea lampreys (Petromyzon marinus) attached to northern right whales, Eubalaena glacialis (Nichols and Hamilton 2004), and minke whales, Balaenoptera acutorostrata (Nichols and Tscherter 2011), in the western North Atlantic conclusively showed that lampreys do associate with those species. Similar evidence for other cetaceans is still lacking

External fixator configurations in tibia fractures: 1D optimization and 3D analysis comparison

The use of external fixation devices in orthopedic surgery is very common in open tibial fractures. A properly applied fixator may improve the healing process while one improperly applied might delay the healing process. The several external fixator systems used in clinical today, can be categorized into uniplanar–unilateral, uniplanar–bilateral, biplanar and multiplanar. The stability on the fracture focus and, therefore, the fracture healing process, is related with the type of external fixator configuration that is selected. The aim of this study is to discuss the principles for the successful application of unilateral–uniplanar external fixation, the assembly of its components, for the case of a transverse fractures using computational models. In this context, the fixation stiffness characteristics are evaluated using a simplified 1D finite element model for the tibia and external fixator. The beams are modeled with realistic cross-sectional geometry and material properties instead of a simplified model. The VABS (the Variational Asymptotic Beam Section analysis) methodology is used to compute the cross-sectional model for the generalized Timoshenko model, which was embedded in the finite element solver FEAP. The use of Timoshenko beam theory allows accounting for several kinds of loads, including torsion moments. Optimal design is performed with respect to the assembly of fixator components using a genetic algorithm. The optimization procedure is based on the evaluation of an objective function, which is dependent on the displacement at the fracture focus. The initial and optimal results are compared by performing a 3D analysis, for which different three-dimensional finite element models are created. The geometrical model of a tibia is created on the basis of data acquired by CAT scan, made for a healthy tibia of a 22 year old male. The 3D comparison of the 1D optimal results show a clear improvement on the objective function for the several load cases and, therefore, it is shown that appropriate selection of the external fixator geometrical features can lead to an improvement on the stability of the external fixator. The results obtained show that the optimal position of the side beam and the first pin should be as close as possible to the bone interface and as close as possible to the fracture focus, respectively. Concerning the second pin, it should be placed away from the first pin in case of flexion loads, to axial and torsion loads the second pin should be placed near the first pin

Numerical study of an impulse wave generated by a sliding mass

© 2018 WIT PressIn this work, a numerical framework for the direct numerical simulation of tsunami waves generated by landslide events is proposed. The method, implemented on the TermoFluids numerical platform, adopts a free surface model for the simulation of momentum equations; thus, considering the effect of air on the flow physics negligible. The effect of the solid motion on the flow is taken into account by means of a direct forcing immersed boundary method (IBM). The method is available for 3-D unstructured meshes; however, it can be integrated with an adaptive mesh refinement (AMR) tool to dynamically increase the local definition of the mesh in the vicinity of the interfaces, which separate the phases or in the presence of vortical structures. The method is firstly validated by simulating the entrance of objects into still water surfaces for 2-D and 3-D configurations. Next, the case of tsunami generation from a subaerial landslide is studied and the results are validated by comparison to experimental and numerical measurements. Overall, the model demonstrates its efficiency in the simulation of this type of physics, and a wide versatility in the choice of the domain discretization.Peer ReviewedPostprint (published version