Atmospheric Abundances, Trends and Emissions of CFC-216ba, CFC-216ca and HCFC-225ca

The first observations of the feedstocks, CFC-216ba (1,2-dichlorohexafluoropropane) and CFC-216ca (1,3-dichlorohexafluoropropane), as well as the CFC substitute HCFC-225ca (3,3-dichloro-1,1,1,2,2-pentafluoropropane), are reported in air samples collected between 1978 and 2012 at Cape Grim, Tasmania. Present day (2012) mixing ratios are 37.8 ± 0.08 ppq (parts per quadrillion; 1015) and 20.2 ± 0.3 ppq for CFC-216ba and CFC-216ca, respectively. The abundance of CFC-216ba has been approximately constant for the past 20 years, whilst that of CFC-216ca is increasing, at a current rate of 0.2 ppq/year. Upper tropospheric air samples collected in 2013 suggest a further continuation of this trend. Inferred annual emissions peaked 421 at 0.18 Gg/year (CFC-216ba) and 0.05 Gg/year (CFC-216ca) in the mid-1980s and then decreased sharply as expected from the Montreal Protocol phase-out schedule for CFCs. The atmospheric trend of CFC-216ca and CFC-216ba translates into continuing emissions of around 0.01 Gg/year in 2011, indicating that significant banks still exist or that they are still being used. HCFC-225ca was not detected in air samples collected before 1992. The highest mixing ratio of 52 ± 1 ppq was observed in 2001. Increasing annual emissions were found in the 1990s (i.e., when HCFC-225ca was being introduced as a replacement for CFCs). Emissions peaked around 1999 at about 1.51 Gg/year. In accordance with the Montreal Protocol, restrictions on HCFC consumption and the short lifetime of HCFC-225ca, mixing ratios declined after 2001 to 23.3 ± 0.7 ppq by 2012

First atmospheric observations of three chlorofluorocarbons

We report the first atmospheric observations of the Chlorofluorocarbons (CFCs) trifluorochloroethene, 3-chloropentafluoropropene and 4,4-dichlorohexafluoro-1-butene by means of Gas Chromatography with Electron Capture and Mass Spectrometric detection (GC-ECD-MS) in air samples taken at the Taunus Observatory operated by the University of Frankfurt (Main) and the Jungfraujoch High Altitude Research Station in Switzerland. These substances belong to a class of CFCs containing a double bond and are suspected to originate from the production and thermal degradation of widely used fluoropolymers like polychlorotrifluoroethene (PCTFE). Their atmospheric lifetimes are expected to be rather short. A quantitative calibration could only be derived for trifluorochloroethene but not for the other species by now. Thus, we use a relative sensitivity method to get a first indication of the observed atmospheric abundances. Identification was possible because of an air plume containing high concentrations of these substances. We suggest that the abundances found on this occasion originated from a local source. However, we have also observed the novel CFCs in air masses representative of background conditions, though with much lower concentrations. These species and some of their degradation products are toxic and could also be relevant for stratospheric and tropospheric ozone depletion

GPS experiments

A method of collecting positional data has been devised using the Federal Aviation Administration (FAA) receiver built by Lincoln Labs which was originally designed for service as a long-term monitoring station. Modification of the receiver continues and this will allow its use as an aircraft navigator. Additional effort has been spent on the development of an experimental receiver or test bed receiver that would allow modification and implementation of new Global Positioning System (GPS) receiver design concepts

Introduction: Why Should We Study Migration Policies at the Interface between Empirical Research and Normative Analysis?

The text introduces the concept behind the Proceedings of the 2018 ZiF Workshop “Studying Migration Policies at the Interface between Empirical Research and Normative Analysis”. It explains why there is a need to study migration policies across disciplines, includes a short note on the current literature, and provides a look back at the workshop. DOI:10.17879/1519962468

Changing aspirations, cultural models of success, and social mobility in northern Ghana

In northern Ghana, many young people, but also parents, teachers, and local authorities, believe that formal education and professional careers provide the only effective means for the rural youth to get ahead. This paper shows how aspirations have been historically changing and analyses in how far new career pathways lead to upward social mobility. Results from qualitative and quantitative research show how weak public education and a lack of educational funding as well as employment opportunities frustrate local aspirations and undermine upward social mobility. However, cultural models of personal success based on an interesting mix of local social values and developmental discourses afford the marginalized youth avenues to social recognition and status

Promise and perils of water reform: Perspectives from Northern Ghana

In 1996, the Ghanaian government has started a water reform process, which put the countries water resources under the control of the Water Resources Commission (WRC). This appointed commission consists of representatives of water providers, statutory regulatory agencies, irrigation officials, NGOs, women and traditional authorities. This commission has been assigned the task to ensure the economically efficient, ecologically sustainable, socially equitable and gender sensitive development of the country's water resources. Using patterns of resource management in the irrigation sector of northern Ghana as example, this article shows that serious obstacles towards the local implementation of the water reform exist. Currently the management and allocation of resources is largely disobeying the regulations, rules and laws set out by various official agencies. Competing local authorities and institutions, lacking legitimacy and enforceability of official rules, as well as corruption, nepotism and political clientelism make resource management prone to conflicts, contestations and renegotiations. Non-transparent and irresponsible resource management compromises the efficiency, sustainability and equity of the irrigation sector. As the WRC lacks the competencies and resources to manage water resources at the local level, but has to rely on already existing structures the prospects for the implementation the water reform remains therefore questionable

Potentiation of glycine-gated NR1/NR3A NMDA receptors relieves Ca2+-dependent outward rectification

Glycine has diverse functions within the mammalian central nervous system. It inhibits postsynaptic neurons via strychnine-sensitive glycine receptors (GlyRs) and enhances neuronal excitation through co-activation of N-methyl-D-aspartate (NMDA) receptors. Classical Ca2+-permeable NMDA receptors are composed of glycine-binding NR1 and glutamate-binding NR2 subunits, and hence require both glutamate and glycine for efficient activation. In contrast, recombinant receptors composed of NR1 and the glycine binding NR3A and/or NR3B subunits lack glutamate binding sites and can be activated by glycine alone. Therefore these receptors are also named “excitatory glycine receptors”. Co-application of antagonists of the NR1 glycine-binding site or of the divalent cation Zn2+ markedly enhances the glycine responses of these receptors. To gain further insight into the properties of these glycine-gated NMDA receptors, we investigated their current-voltage (I–V) dependence. Whole-cell current-voltage relations of glycine currents recorded from NR1/NR3B and NR1/NR3A/NR3B expressing oocytes were found to be linear under our recording conditions. In contrast, NR1/NR3A receptors displayed a strong outwardly rectifying I–V relation. Interestingly, the voltage-dependent inward current block was abolished in the presence of NR1 antagonists, Zn2+ or a combination of both. Further analysis revealed that Ca2+ (1.8 mM) present in our recording solutions was responsible for the voltage-dependent inhibition of ion flux through NR1/NR3A receptors. Since physiological concentrations of the divalent cation Mg2+ did not affect the I–V dependence, our data suggest that relief of the voltage-dependent Ca2+ block of NR1/NR3A receptors by Zn2+ may be important for the regulation of excitatory glycinergic transmission, according to the Mg2+-block of conventional NR1/NR2 NMDA receptors. Keywords: NMDA receptor, excitatory glycine receptor, voltage block, NR3 subunit, supralinear potentiation, Zn2+, NR1 antagonist, ligand-binding domai

Creative bureaucracy: Balancing power in irrigation administration in northern Ghana

Since irrigation development in northern Ghana has started, the natural resources water and land within irrigation schemes have officially become the property of the government. The management of these resources has been put in the hands of an irrigation bureaucracy that is supposed to ensure a sustainable and efficient use of these resources. However, the irrigation bureaucracy does not operate in a vacuum. The irrigation bureaucracy's control over land is contested and land use decisions are influenced by various actors, such as farmers, village committees, chiefs, earth priests and local politicians, which pursue their own political interests and refer to local institutional frameworks that collide with official legislation. To maintain their control of resources, irrigation bureaucrats need to carefully balance power and interests. State bureaucrats rather than taking hegemonic decisions - try to negotiate resources and outwit other actors in order to maintain authority and obtain legitimacy, even if they are not always able to determine actual decision making. In order to live up to their responsibility, and to defend their authority, they not only refer to power and legislation emanating from the state, but take a pragmatic/opportunistic approach in which short-term alliances with local 'big men' as well as references to 'traditional' and 'neo-traditional' norms are of importance. This typical for the performance of African bureaucracies in (rural) areas where state hegemony has been partially established, but where the control of resources continues to be negotiated between different powerful actors, with reference to competing institutional regimes. Here, administration is less bureaucratic control via a fixed set of official regulations, but the creative working of political arenas that are earmarked by competing sources of power and normative frameworks