Signatures of topological branched covers

Let $X^4$ and $Y^4$ be smooth manifolds and $f: X\to Y$ a branched cover with branching set $B$. Classically, if $B$ is smoothly embedded in $Y$, the signature $\sigma(X)$ can be computed from data about $Y$, $B$ and the local degrees of $f$. When $f$ is an irregular dihedral cover and $B\subset Y$ smoothly embedded away from a cone singularity whose link is $K$, the second author gave a formula for the contribution $\Xi(K)$ to $\sigma(X)$ resulting from the non-smooth point. We extend the above results to the case where $Y$ is a {\it topological} four-manifold and $B$ is locally flat, away from the possible singularity. Owing to the presence of non-locally-flat points on $B$, $X$ in this setting is a stratified pseudomanifold, and we use the Intersection Homology signature of $X$, $\sigma_{IH}(X)$. For any knot $K$ whose determinant is not $\pm 1$, a homotopy ribbon obstruction is derived from $\Xi(K)$, providing a new technique to potentially detect slice knots that are not ribbon

Climate variability and vulnerability to poverty in Nicaragua

This study considers the effect of climate variability on vulnerability to poverty in Nicaragua. It discusses how such vulnerability could be measured and which heterogeneous effects can be expected. A multilevel empirical framework is applied, linking per capita consumption to household, regional and climate characteristics. Results confirm a negative effect of climate variability on consumption per capita of Nicaraguan households. This suggests the need for stronger public policies and more resources in order to adapt to the effect of climate change. Furthermore, the poverty reduction attainments reached since the 1990s could be jeopardized if this vulnerability persists

Media and communication considerations to influence the buying decisions of farmers

The agricultural market is an extremely large and extremely important segment of our economy. Agriculture, and the support services provided to agriculture, account for a $1.2 trillion market. This figure is roughly equal to ALL the assets of the Fortune 500 companies combined (Wefald, 1982). Because of the size of this market, it is important, as marketers, to understand the farmer, his media habits and his buying habits. It is important to know what factors carry the most weight when the farmer\u27s decision making process gets underway. It is essential to know how to reach the farmer in each of the stages in his decision making process so that marketers can present product information and help influence the buying decision

An Evaluation into Pilot Proficiency Assessment and the Current State of Training in the Industry

Pilot proficiency assessment has been a debated topic, especially in recent years. Determining effective ways to assess proficiency has been the focus of many industries, including similar high-risk industries such as health care and nuclear power industries. For the purposes of this paper, a comprehensive investigation into the current state of pilot training was conducted to analyze and compare curriculum components, proficiency levels, assessment methods and overall safety outcomes of each instructional program. This analysis includes pilot training programs from the United States, Australia and the European Union, as they relate to pilot licensing. As flight training technology and hour requirements increase, alternate methods of instruction have become more prominent in the industry worldwide. Evaluating the mechanisms that comprise the various international instructional programs, such as the training devices and hours accrued in these devices, is important in understanding how they affect and influence proficiency levels and safety

Pilot Perceptions on Impact of Crew Rest Regulations on Safety and Fatigue

The risk of fatigue on pilot performance and safety is well recognized in aviation. In response to increased safety concerns, the Federal Aviation Administration addressed fatigue risk for passenger airline pilots in Title 14 Code of Federal Regulations Part 117, which included accommodations to address fatigue related risk-factors such as circadian rhythm and the phenomenon commonly described as jet-lag. The rule became effective in January 2014. A survey was conducted in March and April of 2014 to better understand pilot perceptions of the new Part 117 rule. This study analyzed survey responses from 92 self-identified pilots to determine the effect of these new regulations on pilot perception of safety and level of fatigue. The analysis of survey responses to 5-point Likert-scale questions suggested that 43% of pilots felt a positive impact on overall safety, contrasted to 30% of pilots who felt a negative impact on overall safety. Twenty-seven percent of pilots indicated that Part 117 did not have an impact on safety. For perceived level of fatigue, 35% of participants felt a positive impact of Part 117, whereas 33% of participants indicated a negative impact on their fatigue level. Thirty-three percent of participants felt no impact of Part 117 on their overall fatigue level. When asked if cargo operations should be included in the new regulations, 79% of respondents agreed. A qualitative analysis of open-ended comments provided by pilots revealed that negative perceptions of the new regulations were most frequently mentioned

The magnesium isotope record of cave carbonate archives

Here we explore the potential of magnesium (δ<sup>26</sup>Mg) isotope time-series data as continental climate proxies in speleothem calcite archives. For this purpose, a total of six Pleistocene and Holocene stalagmites from caves in Germany, Morocco and Peru and two flowstones from a cave in Austria were investigated. These caves represent the semi-arid to arid (Morocco), the warm-temperate (Germany), the equatorial-humid (Peru) and the cold-humid (Austria) climate zones. Changes in the calcite magnesium isotope signature with time are compared against carbon and oxygen isotope records from these speleothems. Similar to other proxies, the non-trivial interaction of a number of environmental, equilibrium and disequilibrium processes governs the δ<sup>26</sup>Mg fractionation in continental settings. These include the different sources of magnesium isotopes such as rainwater or snow as well as soil and host rock, soil zone biogenic activity, shifts in silicate versus carbonate weathering ratios and residence time of water in the soil and karst zone. Pleistocene stalagmites from Morocco show the lowest mean δ<sup>26</sup>Mg values (GDA: −4.26 ± 0.07‰ and HK3: −4.17 ± 0.15‰), and the data are well explained in terms of changes in aridity over time. The Pleistocene to Holocene stalagmites from Peru show the highest mean value of all stalagmites (NC-A and NC-B δ<sup>26</sup>Mg: −3.96 ± 0.04‰) but only minor variations in Mg-isotope composition, which is consistent with the rather stable equatorial climate at this site. Holocene stalagmites from Germany (AH-1 mean δ<sup>26</sup>Mg: −4.01 ± 0.07‰; BU 4 mean δ<sup>26</sup>Mg: −4.20 ± 0.10‰) suggest changes in outside air temperature was the principal driver rather than rainfall amount. The alpine Pleistocene flowstones from Austria (SPA 52: −3.00 ± 0.73‰; SPA 59: −3.70 ± 0.43‰) are affected by glacial versus interglacial climate change with outside air temperature affecting soil zone activity and weathering balance. Several δ<sup>26</sup>Mg values of the Austrian and two δ<sup>26</sup>Mg values of the German speleothems are shifted to higher values due to sampling in detrital layers (Mg-bearing clay minerals) of the speleothems. The data and their interpretation shown here highlight the potential but also the limitations of the magnesium isotope proxy applied in continental climate research. An obvious potential lies in its sensitivity for even subtle changes in soil-zone parameters, a hitherto rather poorly understood but extremely important component in cave archive research. Limitations are most obvious in the low resolution and high sample amount needed for analysis. Future research should focus on experimental and conceptual aspects including quantitative and well-calibrated leaching and precipitation experiments

Measurement and analysis of spatial reactor profiles in high temperature catalysis research

Spatial reactor profile measurements are a novel tool in chemical reaction engineering research. In this technique species concentrations or molar flow rates, phase temperatures and spectroscopic information are measured as function of the axial coordinate in a continuous flow tubular reactor. The obtained spatial gradients can be analyzed in terms of kinetic and mechanistic information about the reaction under study. The advantage of the spatial profile technique is that transient data are obtained at steady state and that it can be applied at temperature and pressure conditions relevant for industrial application. After a detailed description of the method various application examples are discussed such as methane catalytic partial oxidation on rhodium and platinum coated foam catalysts, methane oxidative coupling in the gas phase and oxidative dehydrogenation of ethane to ethylene on a supported molybdenum oxide catalyst. It is demonstrated how information about film transport limitation and reaction pathways can be extracted. The importance of spatial reactor profiles for validation of microkinetic models is highlighted for gas phase methane oxidative coupling at elevated pressure. Finally the idea of spatially resolved Raman spectroscopy using an optical fiber sensor is demonstrated and key parameters such as spatial resolution and position accuracy are determined