We find that people revise their beliefs about climate change upward when experiencing warmer than usual temperatures in their area. Using international data, we show that attention to climate change, as proxied by Google search volume, increases when the local temperature is abnormally high. In financial markets, stocks of carbon-intensive firms underperform firms with low carbon emissions in abnormally warm weather. Retail investors (not institutional investors) sell carbon-intensive firms in such weather, and return patterns are unlikely to be driven by changes in fundamentals. Our study sheds light on peoples’ collective beliefs and actions about global warming.
Room temperature ferromagnetism has been observed in ZnO nanorods prepared by hydrothermal method. Saturation magnetization of ϳ0.004 emu/ g was measured in the nanorods with diameters of ϳ10 nm and lengths of below 100 nm, and the magnetization reduced with the increase of the size. Annealing of the samples at 900°C in air completely transformed the nanorods into twinning structures and weakened the magnetizations. The mechanism of morphology transformation was discussed. Analysis indicates that the interstitial zinc at the surface may contribute to the ferromagnetism in ZnO nanorods.As ideal candidate materials for spintronic devices, ZnObased diluted magnetic semiconductors ͑DMSs͒ have attracted much attention in recent years. In particular, onedimensional ͑1D͒ ZnO nanostructures which can serve as building blocks for nanoscale devices have been intensively studied. 1-9 Room temperature ͑RT͒ ferromagnetism ͑FM͒ has been achieved in several transition metal ͑TM͒ doped ZnO nanorods, 2-4 nanowires, 6-8 and nanoneedles. 9 On the other hand, RT FM has also been observed in pure ZnO nanoparticles and thin films, 10-12 which shows that FM may be an intrinsic characteristic of ZnO with low dimensionality. Recently, Banerjee et al. 11 reported the enhancement of RT FM in ZnO particles by 900°C annealing in air and related the phenomenon to oxygen vacancy clusters. However, the study on the RT FM in ZnO thin films confirmed that the source of the FM cannot be oxygen vacancies but defects on Zn sites. 12 So far, the understanding of FM origination in ZnO is still insufficient, partly because the reports of RT FM in pure ZnO are rare. Moreover, while annealing treatments were processed in several researches, 6,11 the impact of annealing on the morphology change was seldom considered. In this letter, we report on the RT FM in ZnO nanorods. Annealing of the samples at 900°C in air for 2 h can completely transform the nanorods into twinning structures, while adjusting the intrinsic defects and reducing the saturation magnetization ͑M s ͒.ZnO nanorods were synthesized by hydrothermal method. Zn͑Ac͒ 2 ·2H 2 O and NaOH with a mole ratio of 1:10 were added to absolute ethanol and pretreated in an ultrasonic water bath for 30 min, then hydrothermally treated at 120°C for 5 h. The products were collected by centrifugation and thoroughly washed with distilled water and ethanol, and finally dried at 70°C for 10 h. Two kinds of samples were prepared with different Zn͑Ac͒ 2 ·2H 2 O concentrations of 0.0125M and 0.05M, and denoted as S1 and S2, respectively. The as-prepared samples were annealed at 900°C in air for 2 h. The structure and morphology of the samples were characterized by x-ray diffraction ͑XRD͒, scanning electron microscopy ͑SEM͒, and transmission EM ͑TEM͒.Magnetic properties were measured using an alternative gradient magnetometer. Photoluminescence ͑PL͒ studies were carried out at RT with the excited wavelength of 325 nm. Figure 1 shows the XRD patterns of the as-prepared and annealed samples. All diffraction peaks corr...
By exploiting variation in state capital gains taxation as an instrument, we analyze the economic consequences of housing speculation during the U.S. housing boom in the 2000s. We find that housing speculation, anchored, in part, on extrapolation of past housing price changes, led not only to greater price appreciation, economic expansions, and housing construction during the boom in [2004][2005][2006], but also to more severe economic downturns during the subsequent bust in 2007-2009. Our analysis supports supply overhang and local household demand as two key channels for transmitting these adverse effects.
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