Overcoming Obstacles - Biomimetic Lessons from the Swarming Behavior of Artemia Franciscana

We investigated the formation of Artemia franciscana swarms of freshly hatched instar I nauplii larvae. Nauplii were released into light gradients but then interrupted by light-direction changes, small obstacles, or long barriers. All experiments were carried out horizontally. Each experiment used independent replicates. Freshly produced Artemia broods were harvested from independent incubators thus providing true replicate cohorts of Artemia subjected as replicates to the experimental treatments. We discovered that Artemia nauplii swarms can: 1. repeatedly react to non-obstructed light gradients that undergo repeated direction-changes and do so in a consistent way, 2. find their way to a light source within maze-like arrangements made from small transparent obstacles, 3. move as a swarm around extended transparent barriers, following a light gradient. This paper focuses on the recognition of whole-swarm behaviors, the description thereof and the recognition of differences in whole-swarm movements comparing non-obstructed swarming with swarms encountering obstacles. Investigations of the within-swarm behaviors of individual Artemia nauplii and their interactions with neighboring nauplii are in progress, e.g. in order to discover the underlying swarming algorithms and differences thereof comparing non-obstructed vs. obstructed pathways

Geometrische Interpretationen und Algorithmische Verifikation von exakten Lösungen in Compressed Sensing

In an era dominated by the topic big data, in which everyone is confronted with spying scandals, personalized advertising, and retention of data, it is not surprising that a topic as compressed sensing is of such a great interest. Further the field of compressed sensing is very interesting for problems in signal- and image processing. Similarly, the question arises how many measurements are necessarily required to capture and represent high-resolution signal or objects. In the thesis at hand, the applicability of three of the most applied optimization problems with linear restrictions in compressed sensing is studied. These are basis pursuit, analysis l1-minimization und isotropic total variation minimization. Unique solutions of basis pursuit and analysis l1-minimization are considered and, on the basis of their characterizations, methods are designed which verify whether a given vector can be reconstructed exactly by basis pursuit or analysis l1-minimization. Further, a method is developed which guarantees that a given vector is the unique solution of isotropic total variation minimization. In addition, results on experiments for all three methods are presented where the linear restrictions are given as a random matrix and as a matrix which models the measurement process in computed tomography. Furthermore, in the present thesis geometrical interpretations are presented. By considering the theory of convex polytopes, three geometrical objects are examined and placed within the context of compressed sensing. The result is a comprehensive study of the geometry of basis pursuit which contains many new insights to necessary geometrical conditions for unique solutions and an explicit number of equivalence classes of unique solutions. The number of these equivalence classes itself is strongly related to the number of unique solutions of basis pursuit for an arbitrary matrix. In addition, the question is addressed for which linear restrictions do exist the most unique solutions of basis pursuit. For this purpose, upper bounds are developed and explicit restrictions are given under which the most vectors can be reconstructed via basis pursuit.In Zeiten von Big Data, in denen man nahezu täglich mit Überwachungsskandalen, personalisierter Werbung und Vorratsdatenspeicherung konfrontiert wird, ist es kein Wunder dass ein Forschungsgebiet wie Compressed Sensing von so grossem Interesse ist. Es stellt sich die Frage, wie viele Messungen tatsächlich nötig sind, um ein Signal oder ein Objekt hochaufgelöst darstellen zu können. In der vorliegenden Arbeit wird die Anwendungsmöglichkeit von drei in Compressed Sensing verwendeten Optimierungsprobleme mit linearen Nebenbedingungen untersucht. Hierbei handelt es sich namentlich um Basis Pursuit, Analysis l1-Minimierung und Isotropic Total Variation. Es werden eindeutige Lösungen von Basis Pursuit und der Analysis l1-Minimierung betrachtet, um auf der Grundlage ihrer Charakterisierungen Methoden vorzustellen, die Verifizieren ob ein gegebener Vektor exakt durch Basis Pursuit oder der Analysis l1-Minimierung rekonstruiert werden kann. Für Isotropic Total Variation werden hinreichende Bedingungen aufgestellt, die garantieren, dass ein gegebener Vektor die eindeutige Lösung von Isotropic Total Variation ist. Darüber hinaus werden Ergebnisse zu Experimenten mit Zufallsmatrizen als linearen Nebenbedingungen sowie Ergebnisse zu Experimenten mit Matrizen vorgestellt, die den Aufnahmeprozess bei Computertomographie simulieren. Weiterhin werden in der vorliegenden Arbeit verschiedene geometrische Interpretationen von Basis Pursuit vorgestellt. Unter Verwendung der konvexen Polytop-Theorie werden drei unterschiedliche geometrische Objekte untersucht und in den Zusammenhang mit Compressed Sensing gestellt. Das Ergebnis ist eine umfangreiche Studie der Geometrie von Basis Pursuit mit vielen neuen Einblicken in notwendige geometrische Bedingungen für eindeutige Lösungen und in die explizite Anzahl von Äquivalenzklassen eindeutiger Lösungen. Darüber hinaus wird der Frage nachgegangen, unter welchen linearen Nebenbedingungen die meisten eindeutigen Lösungen existieren. Zu diesem Zweck werden obere Schranken entwickelt, sowie explizite Nebenbedingungen genannt unter denen die meisten Vektoren exakt rekonstruiert werden können

Testable uniqueness conditions for empirical assessment of undersampling levels in total variation-regularized X-ray CT

We study recoverability in fan-beam computed tomography (CT) with sparsity and total variation priors: how many underdetermined linear measurements suffice for recovering images of given sparsity? Results from compressed sensing (CS) establish such conditions for, e.g., random measurements, but not for CT. Recoverability is typically tested by checking whether a computed solution recovers the original. This approach cannot guarantee solution uniqueness and the recoverability decision therefore depends on the optimization algorithm. We propose new computational methods to test recoverability by verifying solution uniqueness conditions. Using both reconstruction and uniqueness testing we empirically study the number of CT measurements sufficient for recovery on new classes of sparse test images. We demonstrate an average-case relation between sparsity and sufficient sampling and observe a sharp phase transition as known from CS, but never established for CT. In addition to assessing recoverability more reliably, we show that uniqueness tests are often the faster option.Comment: 18 pages, 7 figures, submitte

USPOREDBA BROJNOSTI PREDATORA I RAZNOLIKOSTI RIBA U ZAŠTIĆENIM PODRUČJIMA (NP KORNATI, HRVATSKA) I SUSJEDNIM PODRUČJIMA U KOJIMA JE DOZVOLJEN RIBOLOV

Fishing activities and other anthropogenic influences have direct and indirect effects on fish community structure. One expectation may be that with increasing fishing pressure and decreasing size selectivity of fisheries all predator populations decline and consequently fish assemblages change. Comparisons of MPAs with unprotected areas are considered valid natural experiments to test hypotheses on how predation structures communities. Here we report on the use of a lure-assisted visual census in the Central Croatian Adriatic to assess and compare fish assemblages in MPA sites (Kornati NP) with adjacent unprotected sites. We detected a significant protection effect on mesopredator abundance and overall fish diversity/richness and that protection status explained a significant portion of the fish assemblage variability, all independent of additional predictor variables, like habitat and depth. As we continue to expand the spatiotemporal scale and magnitude of the approach, we hope that it will eventually provide us with a long-term data series needed for testing many hypotheses in coastal ecology, including the effects of MPAs, coastal development, fishing and global climate change on the species interactions, abundance, diversity and assembly of animal species across multiple spatial scales.Ribolovne i druge antropogene aktivnosti izravno i neizravno utječu na sastav zajednica riba. Jedna od pretpostavki je da povećani ribolovni napor dovodi do smanjenja populacije predatorskih vrsta riba što dovodi do promjena u sastavu zajednica riba. Usporedba zaštićenih i nezaštićenih područja smatra se vjerodostojnom eksperimentalnom metodom za testiranje hipoteze na koji način struktura predatora utječe na zajednicu riba. Ovdje predstavljamo rezultate korištenja metode vizualnog cenzusa uz pomoć mamca na području srednjeg Jadrana kako bi procijenili i usporedili sastav zajednica riba u zaštićenom području (NP Kornati) i susjednim nezaštićenim područjima. Zabilježili smo značajan utjecaj zaštite na brojnost meso-predatora i na ukupnu raznolikost/brojnost riba kao i to da je zaštitom moguće objasniti značajan dio varijabilnosti u sastavu zajednica riba, neovisno o drugim faktorima poput tipa staništa ili dubine. Daljnjim proširivanjem naših istraživanja na prostornoj i vremenskoj skali, očekujemo da ćemo prikupiti vrijedne i dugotrajne podatke koji su potrebni kako bismo testirali mnoge pretpostavke u ekologiji priobalne zone, uključujući one o u utjecaju zaštićenih područja, razvoju obale, ribolovu, dostupnosti staništa te globalnim klimatskim promjenama na odnose među različitim vrstama, brojnost, raznolikost i sastav životinjskih vrsta na raznim prostornim skalama

USPOREDBA BROJNOSTI PREDATORA I RAZNOLIKOSTI RIBA U ZAŠTIĆENIM PODRUČJIMA (NP KORNATI, HRVATSKA) I SUSJEDNIM PODRUČJIMA U KOJIMA JE DOZVOLJEN RIBOLOV

Fishing activities and other anthropogenic influences have direct and indirect effects on fish community structure. One expectation may be that with increasing fishing pressure and decreasing size selectivity of fisheries all predator populations decline and consequently fish assemblages change. Comparisons of MPAs with unprotected areas are considered valid natural experiments to test hypotheses on how predation structures communities. Here we report on the use of a lure-assisted visual census in the Central Croatian Adriatic to assess and compare fish assemblages in MPA sites (Kornati NP) with adjacent unprotected sites. We detected a significant protection effect on mesopredator abundance and overall fish diversity/richness and that protection status explained a significant portion of the fish assemblage variability, all independent of additional predictor variables, like habitat and depth. As we continue to expand the spatiotemporal scale and magnitude of the approach, we hope that it will eventually provide us with a long-term data series needed for testing many hypotheses in coastal ecology, including the effects of MPAs, coastal development, fishing and global climate change on the species interactions, abundance, diversity and assembly of animal species across multiple spatial scales.Ribolovne i druge antropogene aktivnosti izravno i neizravno utječu na sastav zajednica riba. Jedna od pretpostavki je da povećani ribolovni napor dovodi do smanjenja populacije predatorskih vrsta riba što dovodi do promjena u sastavu zajednica riba. Usporedba zaštićenih i nezaštićenih područja smatra se vjerodostojnom eksperimentalnom metodom za testiranje hipoteze na koji način struktura predatora utječe na zajednicu riba. Ovdje predstavljamo rezultate korištenja metode vizualnog cenzusa uz pomoć mamca na području srednjeg Jadrana kako bi procijenili i usporedili sastav zajednica riba u zaštićenom području (NP Kornati) i susjednim nezaštićenim područjima. Zabilježili smo značajan utjecaj zaštite na brojnost meso-predatora i na ukupnu raznolikost/brojnost riba kao i to da je zaštitom moguće objasniti značajan dio varijabilnosti u sastavu zajednica riba, neovisno o drugim faktorima poput tipa staništa ili dubine. Daljnjim proširivanjem naših istraživanja na prostornoj i vremenskoj skali, očekujemo da ćemo prikupiti vrijedne i dugotrajne podatke koji su potrebni kako bismo testirali mnoge pretpostavke u ekologiji priobalne zone, uključujući one o u utjecaju zaštićenih područja, razvoju obale, ribolovu, dostupnosti staništa te globalnim klimatskim promjenama na odnose među različitim vrstama, brojnost, raznolikost i sastav životinjskih vrsta na raznim prostornim skalama

Humanoide Roboter: vom Maschinenwesen über Dialogpartner zum Markenbotschafter

Humanoiden Robotern (HRO) wird für die Zukunft eine gewichtige Rolle in unterschiedlichen Lebensbereichen zugeschrieben. In Wissenschaft und Praxis herrscht weitgehende Übereinstimmung, dass sich ihre Einsatzpotenziale mit dem technischen Fortschritt weiter ausdehnen werden. In diesem Zusammenhang stellen HRO ein innovatives Instrument für die Markenführung dar. Insgesamt ist zu konstatieren, dass bis dato kein Roboter in Gänze die kognitiven, sensorischen und motorischen Fähigkeiten besitzt, um vollumfänglich auf Umwelteinflüsse abgestimmt zu reagieren. Dennoch ergeben sich bereits heute interessante Anwendungen mit unmittelbarer Relevanz für die Markenbeeinflussung. Diese reichen von der Generierung von Kundenwissen über die Präsentation von Markeninhalten bis zur empathischen Dialogführung.Humanoid robots are expected to play an important role in different areas of life. There is agreement in science and practice that their potential applications will expand widely with the ongoing technological progress. In this context, humanoid robots represent an innovative tool for brand management. Currently, no robot possesses all cognitive, sensory and motoric skills that are required to fully congruently respond to outside stimuli. Nevertheless, there are already interesting applications with direct relevance for brand perception. These range from the generation of customer knowledge to the presentation of brand content to empathetic dialogues

Fish Monitoring in Kornati National Park: Baited, Remote, Underwater Video (BRUV) Versus Trammel Net Sampling

We evaluated (1) the suitability of two alternative methods for fish monitoring: trammel net sampling and BRUV (Baited Remote Underwater Video), and (2) the potential to cross-calibrate the methods based on a set of shared species with high catch probabilities. A statistical power analysis concluded that BRUV can be conducted with sufficient sample size to perceive small changes in fish populations with high power, and therefore can be used as a sentinel monitoring method. We found that fish species detected by both methods amounted to almost a third of the number of species in each method’s catch, and that 90% of these species are candidates for cross-calibration. 74% of the species at BRUV and 50% at trammel had occurrence probabilities above 10%, a reasonable threshold allowing stock assessment of these species. The sampled and predicted total species richness, extrapolated from the species accumulation curves, were almost identical across methods. We conclude that cross-calibrating the two methods and eventual replacement of the trammel method with non-destructive BRUV is feasible. The most effective areas of improvement are increased BRUV night-sampling effort and increased total sampling size to increase the statistical power of BRUV as a monitoring tool. This work has been supported under the Croatian Science Foundation under the project COREBIO (3107)

Population genomics of an endemic Mediterranean fish: differentiation by fine scale dispersal and adaptation

Este artículo contiene 12 páginas, 5 figuras, 2 tablas.The assessment of the genetic structuring of biodiversity is crucial for management and conservation. For species with large effective population sizes a low number of markers may fail to identify population structure. A solution of this shortcoming can be high-throughput sequencing that allows genotyping thousands of markers on a genome-wide approach while facilitating the detection of genetic structuring shaped by selection. We used Genotyping-by-Sequencing (GBS) on 176 individuals of the endemic East Atlantic peacock wrasse (Symphodus tinca), from 6 locations in the Adriatic and Ionian seas. We obtained a total of 4,155 polymorphic SNPs and we observed two strong barriers to gene flow. The first one differentiated Tremiti Islands, in the northwest, from all the other locations while the second one separated east and south-west localities. Outlier SNPs potentially under positive selection and neutral SNPs both showed similar patterns of structuring, although finer scale differentiation was unveiled with outlier loci. Our results reflect the complexity of population genetic structure and demonstrate that both habitat fragmentation and positive selection are on play. This complexity should be considered in biodiversity assessments of different taxa, including non-model yet ecologically relevant organisms.Acknowledgements This work was supported by project CTM2013-48163 from Ministerio de Economía y Competitividad and by the European FP7 CoCoNet project (Ocean 2011-4, grant agreement #287844). CC, EM and MP are part of the research groups 2014SGR-1364, 2014SGR-120 and 2014SGR-336 of the Generalitat de Catalunya. CC was supported by a grant of the Beatriu de Pinós program of the Generalitat de Catalunya. LZ was supported by the University of Padua grant CPDA148387/14.Peer reviewe