We test if managerial preferences explain how firms hedge using hand-collected data on derivative portfolios in the oil and gas industry. How firms hedge involves choosing between linear contracts and put options, and deciding whether to finance these hedging positions with cash-on-hand or by selling call options. The likelihood of being a hedger increases with CEO age, and near-retirement CEOs pr

PREMISE OF THE STUDY: The role of floral scent in facilitating reproductive isolation between closely related plants remains poorly understood. Yucca brevifolia and Yucca jaegeriana are pollinated by different moth species in allopatry, but in a narrow contact zone, pollinator–host specificity breaks down, resulting in hybridization between species. We explored the chemical basis for reproductive

Three-dimensional (3D), city models have been applied in a variety of fields. One of the main problems in 3D city model utilization, however, is the large volume of data. In this paper, a method is proposed to generalize the 3D building objects in 3D city models at different levels of detail, and to combine multiple Levels of Detail (LODs) for a progressive distribution and visualization of the ci

The Tamaulipas tragedy in 2010 proved a turning point for transit migration politics. This was one of the worst massacres on Mexican territory, in which 72 undocumented migrants, mostly from Central America, were kidnapped, tortured, and their dead bodies piled up in a ditch at a local ranch in the northern Mexican state. With this event, transit migrants became visible through their experiences o

Sverige har sedan december 2008 liberalare regler för arbetskraftsinvandring från ”tredje land” (länder utanför EU/EES) än kanske något annat land. De nya reglerna gäller alla yrken oberoende av kvalifikationsgrad eller om det är fråga om ett bristyrke eller inte. Artikeln handlar om de cirka 500 arbetskraftsmigranter från tredje land som 2012 beviljades arbetstillstånd i restaurang- och städbrans

Water loss is a crucial factor for vegetation in the semi-arid Sahel region of Africa. Global satellite-driven estimates of plant CO2 uptake (gross primary productivity, GPP) have been found to not accurately account for Sahelian conditions, particularly the impact of canopy water stress. Here, we identify the main biophysical limitations that induce canopy water stress in Sahelian vegetation and

It has been shown that vegetation growth in semi-arid regions is important to the global terrestrial CO2 sink, which indicates the strong need for improved understanding and spatially explicit estimates of CO2 uptake (gross primary production; GPP) in semi-arid ecosystems. This study has three aims: (1) to evaluate the MOD17A2H GPP (collection 6) product against GPP based on eddy covariance (EC) f