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    ABSTRACT: We present rest-frame 15 and 24 μm luminosity functions (LFs) and the corresponding star-forming LFs at z < 0.3 derived from the 5MUSES sample. Spectroscopic redshifts have been obtained for ∼98% of the objects and the median redshift is ∼0.12. The 5–35 μm Infrared Spectrograph spectra allow us to estimate accurately the luminosities and build the LFs. Using a combination of starburst and quasar templates, we quantify the star formation (SF) and active galactic nucleus (AGN) contributions in the mid-IR spectral energy distribution. We then compute the SF LFs at 15 and 24 μm, and compare with the total 15 and 24 μm LFs. When we remove the contribution of AGNs, the bright end of the LF exhibits a strong decline, consistent with the exponential cutoff of a Schechter function. Integrating the differential LF, we find that the fractional contribution by SF to the energy density is 58% at 15 μm and 78% at 24 μm, while it goes up to ∼86% when we extrapolate our mid-IR results to the total IR luminosity density. We confirm that the AGNs play more important roles energetically at high luminosities. Finally, we compare our results with work at z ∼ 0.7 and confirm that evolution on both luminosity and density is required to explain the difference in the LFs at different redshifts.
    Full-text · Article · Jan 2016 · The Astrophysical Journal
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    ABSTRACT: Comets rarely come close enough to be studied intensively with Earth-based radar. The most recent such occurrence was when Comet 103P/Hartley 2 passed within 0.12 AU in late 2010 October, less than two weeks before the EPOXI flyby. This offered a unique opportunity to improve pre-encounter trajectory knowledge and obtain complementary physical data for a spacecraft-targeted comet. 103P/Hartley 2 is only the fourth comet nucleus to be imaged with radar and already the second to be identified as an elongated, bilobate object based on its delay-Doppler signature. The images show the dominant spin mode to be a rotation about the short axis with a period of 18.2 hr. The nucleus has a low radar albedo consistent with a surface density of 0.5–1.0 g cm −3 . A separate echo component was detected from large (>cm) grains ejected anisotropically with velocities of several to tens of meters per second. Radar shows that, in terms of large-grain production, 103P/Hartley 2 is an unusually active comet for its size.
    Full-text · Article · Jan 2016 · The Astrophysical Journal Letters
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    ABSTRACT: China has become the world’s largest carbon emitter. Its total carbon emission output from fossil fuel combustion and cement production was approximately 10GtCO2 in 2013. However, less is known about carbon emissions from the production of industrial materials, such as mineral products (e.g., lime, soda ash, asphalt roofing), chemical products (e.g., ammonia, nitric acid) and metal products (e.g., iron, steel and aluminum). Carbon emissions from the production processes of these industrial products (in addition to cement production) are also less frequently reported by current international carbon emission datasets. Here we estimated the carbon emissions resulting from the manufacturing of 5 major industrial products in China, given China’s dominant position in industrial production in the world. Based on an investigation of China’s specific production processes, we devised a methodology for calculating emission factors. The results indicate that China’s total carbon emission from the production of alumina, plate glass, soda ash, ammonia and calcium carbide was 233 million tons in 2013, equivalent to the total CO2 emissions of Spain in 2013. The cumulative emissions from the manufacturing of these 5 products during the period 1990–2013 was approximately 2.5GtCO2, more than the annual total CO2 emissions of India. Thus, quantifying the emissions from industrial processes is critical for understanding the global carbon budget and developing a suitable climate policy.
    Full-text · Article · Dec 2015 · Applied Energy

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Top publications last week by reads

 
Science Advances 01/2016; 2(1):e1500989-e1500989. DOI:10.1126/sciadv.1500989
116 Reads
 
Nature 01/2016; 529(7586). DOI:10.1038/nature16190
103 Reads

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