On Pairwise Costs for Network Flow Multi-Object Tracking

Multi-object tracking has been recently approached with the min-cost network flow optimization techniques. Such methods simultaneously resolve multiple object tracks in a video and enable modeling of dependencies among tracks. Min-cost network flow methods also fit well within the "tracking-by-detection" paradigm where object trajectories are obtained by connecting per-frame outputs of an object detector. Object detectors, however, often fail due to occlusions and clutter in the video. To cope with such situations, we propose to add pairwise costs to the min-cost network flow framework. While integer solutions to such a problem become NP-hard, we design a convex relaxation solution with an efficient rounding heuristic which empirically gives certificates of small suboptimality. We evaluate two particular types of pairwise costs and demonstrate improvements over recent tracking methods in real-world video sequences

Functionalization of sp²-carbon atoms via visible-light photoredox catalysis

This thesis presents various approaches for the photocatalytic functionalization of organic compounds with sp2-hybridized carbon atoms. Visible-light mediated oxidative nitration and chlorination reactions as well as reductive alkenylation and phosphonylation reactions were developed in this context

Coloured migration in the Cape region at the beginning of the twenty-first century

The nature of the urbanisation process among members of the coloured ethnic group in the Western and Northern Cape is changing. Previously, in this region, urbanisation could be described as a process of step-wise gravity flow migration from Cape Town’s hinterland to the metropolitan area. This rural-urban process of migration continues, but the favoured destinations are now regional towns rather than Cape Town itself

Bee conservation: inclusive solutions

Conservation Biolog

Unsupervised Learning from Narrated Instruction Videos

We address the problem of automatically learning the main steps to complete a certain task, such as changing a car tire, from a set of narrated instruction videos. The contributions of this paper are three-fold. First, we develop a new unsupervised learning approach that takes advantage of the complementary nature of the input video and the associated narration. The method solves two clustering problems, one in text and one in video, applied one after each other and linked by joint constraints to obtain a single coherent sequence of steps in both modalities. Second, we collect and annotate a new challenging dataset of real-world instruction videos from the Internet. The dataset contains about 800,000 frames for five different tasks that include complex interactions between people and objects, and are captured in a variety of indoor and outdoor settings. Third, we experimentally demonstrate that the proposed method can automatically discover, in an unsupervised manner, the main steps to achieve the task and locate the steps in the input videos.Comment: Appears in: 2016 IEEE Conference on Computer Vision and Pattern Recognition (CVPR 2016). 21 page

Methane emissions from an alpine fen in central Switzerland

Methane emissions and below ground methane pore water concentrations were determined in an alpine fen at 1,915m a.s.l. in central Switzerland. The fen represented an acidic (pH 4.5-4.9), nutrient-poor to mesotrophic habitat dominated by Carex limosa, Carex rostrata, Trichophorum caespitosum and Sphagnum species. From late fall to late spring the fen was snow-covered. Throughout winter the temperatures never dropped below 0°C at 5cm below the vegetation surface. Methane emissions in June, July, August and September were in the range of 125 (±26)-313 (±71)mgCH4m−2day−1 with a tendency to decrease along the summer season. Mean methane pore water concentrations at a depth of 20-40cm below the vegetation surface were 526 (±32)μM in June and in the range of 144 (±10)-233 (±7)μM in July, August and September. At a depth of 0-20cm the mean methane pore water concentrations dropped back to <20μM with an almost linear decrease between 0 and 15cm. Oxygen pore water concentrations were close to air saturation in the first few centimeters and dropped back below detection limit at a depth of 20cm. In July and August the pore water concentrations of dissolved organic carbon (DOC) were in the range of 7.2-10.1mgCl−1 at all depths. The pore water concentrations of acetate, formate and oxalate were in the range of 2.0-8.2μM at all depths. Methanotrophic and methanogenic communities were quantified using pmoA and mcrA, respectively, as marker genes. The abundances of both communities showed a distinct peak at a depth of 10-15cm below the vegetation surfac

Interaction of Lanthanum with Boron and Carbon: Phase Diagram and Structural Chemistry

International audienceThe isothermal section of the La-B-C phase diagram at 1,270 K has been investigated by means of X-ray, neutron powder diffraction, microstructure and EPMA analyses. Eight ternary compounds were found, and for six of them, the crystal structures have been established. The phase with the structure type of La5B2C6 has a broad homogeneity range described by the formula La5(BC) x (5.6 ≤ x ≤ 8.8). The lanthanum sesquicarbide La2C3 exhibits an extended solid solution in the ternary domain La2C3−x B x (x = 0.4). The boron substitution of carbon leads to the decrease of the superconducting temperature from 13.4 K for La2C3 to 10.0 K for La2C2.8B0.2 and from 5.6 K for La2C2.7 to 4.1 K for La2C2.6B0.4. The compositions of two new compounds ~La4B3C12 and ~La4B5C18 were found via WDX analysis

The equilibrium and spillover effects of early retirement

This paper examines the labor market effects of unemployment insurance extensions. It uses administrative Social Security matched employer-employee data from Austria. Critical components of the analysis are effects on wages as well as retirement/job separation effects. The paper found that: - Older workers are very responsive to unemployment insurance benefit extensions, which in our setting may have served as a bridge into early retirement. - These separations stem from high-value employment relationships, and may constitute inefficient separations. - Wages appear unresponsive to such shifts on workers’ nonemployment outside options, implying that these workers may not be able to use such reforms to improve their bargaining power - even if they are older and on the retirement margin. - However, in a second study, we find no effects on separations of such policies even for older workers. The key difference is that one reform was potential benefit extensions (entailing early retirement) rather than the benefit levels (in increases in the generosity of which even older workers did not separate from their jobs). The policy implications of the findings are: - Unemployment insurance benefit generosity may interact with retirement policies and trigger early retirement among older workers eligible for these benefits. - These separations may be socially inefficient and may therefore have welfare costs. Subsidizing early retirement policies does not entail wage pressure