Measurement report: In situ observations of deep convection without lightning during the tropical cyclone Florence 2018

Hurricane Florence was the sixth named storm in the Atlantic hurricane season 2018. It caused dozens of deaths and major economic damage. In this study, we present in situ observations of trace gases within tropical storm Florence on 2 September 2018, after it had developed a rotating nature, and of a tropical wave observed close to the African continent on 29 August 2018 as part of the research campaign CAFE Africa (Chemistry of the Atmosphere: Field Experiment in Africa) with HALO (High Altitude and LOng Range Research Aircraft). We show the impact of deep convection on atmospheric composition by measurements of the trace gases nitric oxide (NO), ozone (O$_{3}$), carbon monoxide (CO), hydrogen peroxide (H$_{2}$O$_{2}$), dimethyl sulfide (DMS) and methyl iodide (CH$_{3}$I) and by the help of color-enhanced infrared satellite imagery taken by GOES-16. While both systems, i.e., the tropical wave and the tropical storm, are deeply convective, we only find evidence for lightning in the tropical wave using both in situ NO measurements and data from the World Wide Lightning Location Network (WWLLN)

Measurement report: Hydrogen peroxide in the upper tropical troposphere over the Atlantic Ocean and western Africa during the CAFE-Africa aircraft campaign

This study focuses on the distribution of hydrogen peroxide (H2O2) in the upper tropical troposphere at altitudes between 8 and 15 km based on in situ observations during the Chemistry of the Atmosphere: Field Experiment in Africa (CAFE-Africa) campaign conducted in August–September 2018 over the tropical Atlantic Ocean and western Africa. The measured hydrogen peroxide mixing ratios in the upper troposphere show no clear trend in the latitudinal distribution with locally increased levels (up to 1 ppbv​​​​​​​) within the Intertropical Convergence Zone (ITCZ), over the African coastal area, as well as during measurements performed in proximity to the tropical storm Florence (later developing into a hurricane). The observed H2O2 distribution suggests that mixing ratios in the upper troposphere seem to be far less dependent on latitude than assumed previously and the corresponding factors influencing the photochemical production and loss of H2O2. The observed levels of H2O2 in the upper troposphere indicate the influence of convective transport processes on the distribution of the species not only in the tropical but also in the subtropical regions. The measurements are compared to observation-based photostationary steady-state (PSS) calculations and numerical simulations by the global ECHAM/MESSy Atmospheric Chemistry (EMAC) model. North of the ITCZ, PSS calculations produce mostly lower H2O2 mixing ratios relative to the observations. The observed mixing ratios tend to exceed the PSS calculations by up to a factor of 2. With the exception of local events, the comparison between the calculated PSS values and the observations indicates enhanced H2O2 mixing ratios relative to the expectations based on PSS calculations in the north of the ITCZ. On the other hand, PSS calculations tend to overestimate the H2O2 mixing ratios in most of the sampled area in the south of the ITCZ by a factor of up to 3. The significant influence of convection in the ITCZ and the enhanced presence of clouds towards the Southern Hemisphere indicate contributions of atmospheric transport and cloud scavenging in the sampled region. Simulations performed by the EMAC model also overestimate hydrogen peroxide levels particularly in the Southern Hemisphere, most likely due to underestimated cloud scavenging. EMAC simulations and PSS calculations both indicate a latitudinal gradient from the Equator towards the subtropics. In contrast, the measurements show no clear gradient with latitude in the mixing ratios of H2O2 in the upper troposphere with a slight decrease from the ITCZ towards the subtropics, indicating a relatively low dependency on the solar radiation intensity and the corresponding photolytic activity. The largest model deviations relative to the observations correspond with the underestimated hydrogen peroxide loss due to enhanced cloud presence, scavenging, and rainout in the ITCZ and towards the south.</p

Reduced levels of dopamine and altered metabolism in brains of HPRT knock-out rats: a new rodent model of Lesch-Nyhan Disease

Lesch-Nyhan disease (LND) is a severe neurological disorder caused by loss-of-function mutations in the gene encoding hypoxanthine phosphoribosyltransferase (HPRT), an enzyme required for efficient recycling of purine nucleotides. Although this biochemical defect reconfigures purine metabolism and leads to elevated levels of the breakdown product urea, it remains unclear exactly how loss of HPRT activity disrupts brain function. As the rat is the preferred rodent experimental model for studying neurobiology and diseases of the brain, we used genetically-modified embryonic stem cells to generate an HPRT knock-out rat. Male HPRT-deficient rats were viable, fertile and displayed normal caged behaviour. However, metabolomic analysis revealed changes in brain biochemistry consistent with disruption of purine recycling and nucleotide metabolism. Broader changes in brain biochemistry were also indicated by increased levels of the core metabolite citrate and reduced levels of lipids and fatty acids. Targeted MS/MS analysis identified reduced levels of dopamine in the brains of HPRT-deficient animals, consistent with deficits noted previously in human LND patients and HPRT knock-out mice. The HPRT-deficient rat therefore provides a new experimental platform for future investigation of how HPRT activity and disruption of purine metabolism affects neural function and behaviour

Constructing a climate change logic: An institutional perspective on the "tragedy of the commons"

Despite increasing interest in transnational fields, transnational commons have received little attention. In contrast to economic models of commons, which argue that commons occur naturally and are prone to collective inaction and tragedy, we introduce a social constructionist account of commons. Specifically, we show that actor-level frame changes can eventually lead to the emergence of an overarching, hybrid "commons logic" at the field level. These frame shifts enable actors with different logics to reach a working consensus and avoid "tragedies of the commons." Using a longitudinal analysis of key actors' logics and frames, we tracked the evolution of the global climate change field over 40 years. We bracketed time periods demarcated by key field-configuring events, documented the different frame shifts in each time period, and identified five mechanisms (collective theorizing, issue linkage, active learning, legitimacy seeking, and catalytic amplification) that underpin how and why actors changed their frames at various points in time-enabling them to move toward greater consensus around a transnational commons logic. In conclusion, the emergence of a commons logic in a transnational field is a nonlinear process and involves satisfying three conditions: (1) key actors view their fates as being interconnected with respect to a problem issue, (2) these actors perceive their own behavior as contributing to the problem, and (3) they take collective action to address the problem. Our findings provide insights for multinational companies, nation-states, nongovernmental organizations, and other stakeholders in both conventional and unconventional commons

A wireless, passive load cell based on magnetoelastic resonance

A wireless, battery-less load cell was fabricated based on the resonant frequency shift of a vibrating magnetoelastic strip when exposed to an AC magnetic field. Since the vibration of the magnetoelastic strip generated a secondary field, the resonance was remotely detected with a coil. When a load was applied to a small area on the surface of the magnetoelastic strip via a circular rod applicator, the resonant frequency and amplitude decreased due to the damping of its vibration. The force sensitivity of the load cell was controlled by changing the size of the force applicator and placing the applicator at different locations on the strips surface. Experimental results showed that the force sensitivity increased when a larger applicator was placed near the edge of the strip. The novelty of this load cell is not only its wireless passive nature, but also the controllability of the force sensitivity. © 2012 IOP Publishing Ltd

A wireless, passive load cell based on magnetoelastic resonance

A wireless, battery-less load cell was fabricated based on the resonant frequency shift of a vibrating magnetoelastic strip when exposed to an AC magnetic field. Since the vibration of the magnetoelastic strip generated a secondary field, the resonance was remotely detected with a coil. When a load was applied to a small area on the surface of the magnetoelastic strip via a circular rod applicator, the resonant frequency and amplitude decreased due to the damping on its vibration. The force sensitivity of the load cell was controlled by changing the size of the force applicator and placing the applicator at different locations on the strip’s surface. Experimental results showed the force sensitivity increased with a larger applicator placing near the edge of the strip. The novelty of this load cell is not only its wireless passive nature, but also the controllability of the force sensitivity