Mesospheric observations with the EISCAT UHF radar during polar cap absorption events: <br>3. Comparison with simultaneous EISCAT VHF measurements

International audienceMesospheric observations were obtained by the EISCAT UHF and VHF radars during the solar proton event of March 1990. We present the first comparison of incoherent-scatter spectral measurements from the middle mesosphere using simultaneous, co-located observations by the two radars. VHF spectra observed with a vertical antenna were found to be significantly narrower than model predictions, in agreement with earlier UHF results. For antenna pointing directions that were significantly away from the vertical, the wider VHF radar beam gave rise to broadening of the observed spectra due to vertical shears in the horizontal wind. In this configuration, UHF spectral measurements were found to be more suitable for aeronomical applications. Both radar systems provide consistent and reliable estimates of the neutral wind. Spectral results using both the multipulse and pulse-to-pulse schemes were intercompared and their suitability for application to combined mesosphere ? lower thermosphere studies investigated

Is the sky the limit? an analysis of high-rise office buildings

Modern central business districts are characterised by high-rise office buildings. Helsley and Strange (2008) argue that skyscrapers are caused by agglomeration economies and a prize for being the tallest, so a reputation effect. We aim to test the relevance of this model by investigating the impact of building height on commercial office rents. The results show that firms are willing to pay about 4 percent more for a building that is 10 meters taller, which we interpret as the sum of a within-building agglomeration effect and a reputation effect. Using semiparametric techniques, we disentangle reputation effects from agglomeration effects and demonstrate that the reputation effect is substantial for tall buildings. For example, it is at least 17.5 percent of the rent for a building that is 6 times the average height

Import of cytochrome c into mitochondria

The import of cytochrome c into mitochondria can be resolved into a number of discrete steps. Here we report on the covalent attachment of heme to apocytochrome c by the enzyme cytochrome c heme lyase in mitochondria from Neurospora crassa. A new method was developed to measure directly the linkage of heme to apocytochrome c. This method is independent of conformational changes in the protein accompanying heme attachment. Tryptic peptides of [35S]cysteine-labelled apocytochrome c, and of enzymatically formed holocytochrome c, were resolved by reverse-phase HPLC. The cysteine-containing peptide to which heme was attached eluted later than the corresponding peptide from apocytochrome c and could be quantified by counting 35S radioactivity as a measure of holocytochrome c formation. Using this procedure, the covalent attachment of heme to apocytochrome c, which is dependent on the enzyme cytochrome c heme lyase, could be measured. Activity required heme (as hemin) and could be reversibly inhibited by the analogue deuterohemin. Holocytochrome c formation was stimulated 5–10-fold by NADH > NADPH > glutathione and was independent of a potential across the inner mitochondrial membrane. NADH was not required for the binding of apocytochrome c to mitochondria and was not involved in the reduction of the cysteine thiols prior to heme attachment. Holocytochrome c formation was also dependent on a cytosolic factor that was necessary for the heme attaching step of cytochrome c import. The factor was a heat-stable, protease-insensitive, low-molecular-mass component of unknown function. Cytochrome c heme lyase appeared to be a soluble protein located in the mitochondrial intermembrane space and was distinct from the previously identified apocytochrome c binding protein having a similar location. A model is presented in which the covalent attachment of heme by cytochrome c heme lyase also plays an essential role in the import pathway of cytochrome c

Structure and Thermodynamics of the Mixed Alkali Alanates

The thermodynamics and structural properties of the hexahydride alanates (M2M'AlH6) with the elpasolite structure have been investigated. A series of mixed alkali alanates (Na2LiAlH6, K2LiAlH6 and K2NaAlH6) were synthesized and found to reversibly absorb and desorb hydrogen without the need for a catalyst. Pressure-composition isotherms were measured to investigate the thermodynamics of the absorption and desorption reactions with hydrogen. Isotherms for catalyzed (4 mol% TiCl3) and uncatalyzed Na2LiAlH6 exhibited an increase in kinetics, but no change in the bulk thermodynamics with the addition of a dopant. A structural analysis using synchrotron x-ray diffraction showed that these compounds favor the Fm-3m space group with the smaller ion (M') occupying an octahedral site. These results demonstrate that appropriate cation substitutions can be used to stabilize or destabilize the material and may provide an avenue to improving the unfavorable thermodynamics of a number of materials with promising gravimetric hydrogen densities.Comment: 6 pages, 7 figures,3 tables, submitted to PR

TH3.2: Men's rural-to-urban migration in Burundi: effects on on banana farming systems by wives of migrants

Male out-migration triggers organizational changes in households and influences labour expectations, power relations, and agricultural practices of concerned households. It also has important influences on reshaping the family structure and transforming the traditional gender roles in rural societies. This case study draws upon a mixed-methods research design involving 29 semi-structured interviews, 6 focus group discussions, and a household survey (N=180) to shed the light on how a ‘men's crop' is managed by wives in the absence of their out-migrated husbands. While prevailing narratives consider the banana as a ‘men's crop', we highlight the significant ways that household structural changes induced by male out-migration challenge the narratives. In the absence of the out-migrated husbands, the wives become primary decision-makers and have as much interest as men in the banana crop. We find that not having enough land implies not having banana which is the main source of income in Burundi and leads to poverty and male out-migration. At the same time, the migration remittances contribute to the acquisition of land and banana and the wives of migrants play a key role in that process. However, the negative stereotypes surrounding men's views on women's capabilities to manage the farms and existing gender-differentiated norms in the household and on the farm are likely to perpetuate and reinforce existing gender inequalities embedded in the management of the cash crops such as banana. This study suggests exploring shifting gender roles and practices in farm management in the absence of men (rather than relying on stereotypes) as an entry point to advocate on gender transformative approach in agri-food systems in Burundi