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Reliable quantification of natural and anthropogenic gas release (e.g.\ CO2, methane) from the seafloor into the ocean, and ultimately, the atmosphere, is a challenging task. While ship-based echo sounders allow detection of free gas in the water even from a larger distance, exact quantification requires parameters such as rise speed and bubble size distribution not obtainable by such sensors. Optical methods are complementary in the sense that they can provide high temporal and spatial resolution of single bubbles or bubble streams from close distance. In this contribution we introduce a complete instrument and evaluation method for optical bubble stream characterization. The dedicated instrument employs a high-speed deep sea stereo camera system that can record terabytes of bubble imagery when deployed at a seep site for later automated analysis. Bubble characteristics can be obtained for short sequences of few minutes, then relocating the instrument to other locations, or in autonomous mode of intervals up to several days, in order to capture variations due to current and pressure changes and across tidal cycles. Beside reporting the steps to make bubble characterization robust and autonomous, we carefully evaluate the reachable accuracy and propose a novel calibration procedure that, due to the lack of point correspondences, uses only the silhouettes of bubbles. The system has been operated successfully in up to 1000m water depth in the Pacific Ocean to assess methane fluxes. Besides sample results we also report failure cases and lessons learnt during development.

Entrepreneurial support organizations called pacers are helping businesses in emerging markets achieve their goals by providing services for them in the long run. A blueprint for shifting to a pacer model shows how organizations can support entrepreneurs as they grow. Open access to this article made possible by Stanford Seed., Stanford Social Innovation Review, 20(3), 42-49

Entrepreneurs and their ventures are often portrayed as unambiguously positive forces in society. Specifically, high technology and equity-funded startups are heralded for their innovative products and services that are believed to alter the economic, social, and even political fabric of life in advantageous ways. This chapter draws on established theory on the causes of misconduct in and by organizations to elaborate the factors that can give rise to misconduct in entrepreneurial ventures, illustrating our arguments with case material on both widely known and less well-known instances of entrepreneurial misconduct. In venturing into the dark side of entrepreneurship, we hope to contribute to theory on entrepreneurship and organizational misconduct, augment entrepreneurship pedagogy, and offer ideas and examples that can enhance entrepreneurs’ awareness of their susceptibility to wrongdoing.

Over the years, an enormous effort has been made to establish nitrogen vacancy (NV) centers in diamond as easily accessible and precise magnetic field sensors. However, most of their sensing protocols rely on the application of bias magnetic fields, preventing their usage in zero- or low-field experiments. We overcome this limitation by exploiting the full spin $S=1$ nature of the NV center, allowing us to detect nuclear spin signals at zero- and low-field with a linearly polarized microwave field. As conventional dynamical decoupling protocols fail in this regime, we develop new robust pulse sequences and optimized pulse pairs, which allow us to sense temperature and weak AC magnetic fields and achieve an efficient decoupling from environmental noise. Our work allows for much broader and simpler applications of NV centers as magnetic field sensors in the zero- and low-field regime and can be further extended to three-level systems in ions and atoms.

The tight program of scientific research cruises usually does not leave enough time for thorough tests of new research equipment and their system components, nor for extensive pilot and handling training. For this reason, ship time was requested for sea trials of two types of autonomous (not tethered) underwater vehicles owned by GEOMAR, the manned 400-meter submersible JAGO and the Hover-AUVs ANTON and LUISE, type Girona500. The aim was to test several technical and operational aspects with both vehicles at locations with differently structured terrain (from flat ground to steep rocky slopes) and to water depths of up to 500 meters. The Aeolian Islands in the Tyrrhenian Sea north of Sicily were chosen as test area. The volcanic islands offer sheltered sea conditions at their leeway, and bottom currents are usually weak or absent. Rocky and steep slopes are located in short distances to areas with flat underwater topography, providing ideal test conditions.