Hazard index maps for woody material recruitment and transport in alpine catchments

A robust and reliable risk assessment procedure for hydrologic hazards deserves particular attention to the role of transported woody material during flash floods or debris flows. At present, woody material transport phenomena are not systematically considered within the procedures for the elaboration of hazard maps. The consequence is a risk of losing prediction accuracy and of underestimating hazard impacts. Transported woody material frequently interferes with the sediment regulation capacity of open check dams and moreover, when obstruction phenomena at critical crosssections of the stream occur, inundations can be triggered. The paper presents a procedure for the determination of the relative propensity of mountain streams to the entrainment and delivery of recruited woody material on the basis of empirical indicators. The procedure provided the basis for the elaboration of a hazard index map for all torrent catchments of the Autonomous Province of Bolzano/Bozen. The plausibility of the results has been thoroughly checked by a backward oriented analysis on natural hazard events, documented since 1998 at the Department of Hydraulic Engineering of the aforementioned Alpine Province. The procedure provides hints for the consideration of the effects, induced by woody material transport, during the elaboration of hazard zone maps.

Computational Tools for Stereo and Light Field Photography

This thesis covers a broad part of the field of computational photography, including video stabilization and image warping techniques, introductions to light field photography and the conversion of monocular images and videos into stereoscopic 3D content. We present a user assisted technique for stereoscopic 3D conversion from 2D images. Our approach exploits the geometric structure of perspective images including vanishing points. We allow a user to indicate lines, planes, and vanishing points in the input image, and directly employ these as guides of an image warp that produces a stereo image pair. Our method is most suitable for scenes with large scale structures such as buildings and is able to skip the step of constructing a depth map. Further, we propose a method to acquire 3D light fields using a hand-held camera, and describe several computational photography applications facilitated by our approach. As the input we take an image sequence from a camera translating along an approximately linear path with limited camera rotations. Users can acquire such data easily in a few seconds by moving a hand-held camera. We convert the input into a regularly sampled 3D light field by resampling and aligning them in the spatio-temporal domain. We also present a novel technique for high-quality disparity estimation from light fields. Finally, we show applications including digital refocusing and synthetic aperture blur, foreground removal, selective colorization, and others.

What do brain network interactions tell about cognitive processes? How to seek causality?

Optimal adjustment of brain networks allows the biased processing of information in response to the demand of environments and is therefore prerequisite for adaptive behaviour. It is widely shown that a biased state of networks is associated with a particular cognitive process. However, those associations were identified by backward categorization of trials and cannot provide a causal association with cognitive processes. This problem still remains a big obstacle to advance the state of our field in particular human cognitive neuroscience. In my talk, I will present two approaches to address the causal relationships between brain network interactions and behaviour. Firstly, we combined connectivity analysis of fMRI data and a machine leaning method to predict inter-individual differences of behaviour and responsiveness to environmental demands. The connectivity-based classification approach outperforms local activation-based classification analysis, suggesting that interactions in brain networks carry information of instantaneous cognitive processes. Secondly, we have recently established a brand new method combining transcranial alternating current stimulation (tACS), transcranial magnetic stimulation (TMS), and EEG. We use the method to measure signal transmission between brain areas while introducing extrinsic oscillatory brain activity and to study causal association between oscillatory activity and behaviour. We show that phase-matched oscillatory activity creates the phase-dependent modulation of signal transmission between brain areas, while phase-shifted oscillatory activity blunts the phase-dependent modulation. The results suggest that phase coherence between brain areas plays a cardinal role in signal transmission in the brain networks. In sum, I argue that causal approaches will provide more concreate backbones to cognitive neuroscience.

Dialect features indexing hipster identity on social media: the case of the city of Malaga

Identity is a recurrent research interest in current sociolinguistics and it is also of primary interest in digital discourse studies. Identity construction is closely related to stance and style (Eckert 2008; Jaffe 2009), which are fundamental concepts for understanding the language use and its social meanings in the case of social media users from Malaga. As the specific social meanings of a set of dialect features constitute a style, this style and the social (and technological) context in which the variants are used determine the meanings that are actually associated with each variant. Hence, every variant has its own indexical field covering any number of potential meanings. The Spanish spoken in Malaga, as Andalusian Spanish in general, was in the past often times considered an incorrect, low prestige variety of Spanish which was strongly associated with the poor, rural, backward South of Spain. This southern Spanish variety is easily recognised because of its innovative phonetic features that diverge from the national standard. In this study several of these phonetic dialect features are looked at, which users from Malaga purposefully employ (in a textualised form) on social media for identity construction. This identity construction is analysed through interactional and ethnographic methods: A perception and an imitation task served as key data and were supplemented by answers to a series of open questions. Further data stems from visual, multimodal elements (e.g. images, photos, videos) posted by users from the city of Malaga. The program TAMS Analyzer was used for data codification and analysis. Results show that certain features that in spoken language are considered rural and old-fashioned, acquire new meaning on social media, namely of urbanity and fashion. Moreover, these features, if used online, are associated with hipsters. That is, the “cool” social media index the “coolness” of the dialect features in question and, thus, the mediatisation makes their indexical fields even more multi-layered and dynamic. Social media users from Malaga performatively employ these stylised dialect features to project a hipster identity and certain related stances.

Benchmarking numerical models of brittle thrust wedges

We report quantitative results from three brittle thrust wedge experiments, comparing numerical results directly with each other and with corresponding analogue results. We first test whether the participating codes reproduce predictions from analytical critical taper theory. Eleven codes pass the stable wedge test, showing negligible internal deformation and maintaining the initial surface slope upon horizontal translation over a frictional interface. Eight codes participated in the unstable wedge test that examines the evolution of a wedge by thrust formation from a subcritical state to the critical taper geometry. The critical taper is recovered, but the models show two deformation modes characterised by either mainly forward dipping thrusts or a series of thrust pop-ups. We speculate that the two modes are caused by differences in effective basal boundary friction related to different algorithms for modelling boundary friction. The third experiment examines stacking of forward thrusts that are translated upward along a backward thrust. The results of the seven codes that run this experiment show variability in deformation style, number of thrusts, thrust dip angles and surface slope. Overall, our experiments show that numerical models run with different numerical techniques can successfully simulate laboratory brittle thrust wedge models at the cm-scale. In more detail, however, we find that it is challenging to reproduce sandbox-type setups numerically, because of frictional boundary conditions and velocity discontinuities. We recommend that future numerical-analogue comparisons use simple boundary conditions and that the numerical Earth Science community defines a plasticity test to resolve the variability in model shear zones.

A potential case of attitude change: The Spanish spoken in the city of Malaga and used on social network sites

The Spanish spoken in the city of Malaga, as Andalusian Spanish in general, was in the past often times considered an incorrect, low prestige variety of Spanish which was strongly associated with the poor, rural, backward South of Spain. This southern Spanish variety is easily recognised because of its innovative phonetic features that diverge from the national standard, even though in the past years in the case of some features a convergence to the standard could be observed. Despite its low prestige the local variety of Spanish is quite often used on social network sites, where it is considered as urban, fashion and cool. Thus, this paper aims at analysing whether the Spanish used in the city of Malaga is undergoing an attitude change. The study draws on naturally occurring speech, data extracted from Facebook and a series of questionnaires about the salience, attitude and perception of the local variety of Spanish. The influence of the social factors age and gender is analysed, since they are both known to play a crucial role in many instances of language change. The first is of special interest, as during the Franco dictatorship dialect use was not accepted in schools and in the media. Results show that, on the one hand, people from Malaga hold a more positive attitude towards non-standard features used on social network sites than in spoken language. On the other hand, young female users employ most non-standard features online and unsurprisingly have an extremely positive attitude towards this use. However, in spoken Spanish the use and attitude of some features is led by men and speakers educated during the Franco dictatorship, while other features, such as elision of intervocalic /d/, elision of final /ɾ/, /l/ and /d/ and ceceo, are predominantly employed by and younger speakers and women. These features are considered as salient in the local variety and work as local identity markers.