NMA: Neural Multi-slot Auctions with Externalities for Online Advertising

Online advertising driven by auctions brings billions of dollars in revenue for social networking services and e-commerce platforms. GSP auctions, which are simple and easy to understand for advertisers, have almost become the benchmark for ad auction mechanisms in the industry. However, most GSP-based industrial practices assume that the user click only relies on the ad itself, which overlook the effect of external items, referred to as externalities. Recently, DNA has attempted to upgrade GSP with deep neural networks and models local externalities to some extent. However, it only considers set-level contexts from auctions and ignores the order and displayed position of ads, which is still suboptimal. Although VCG-based multi-slot auctions (e.g., VCG, WVCG) make it theoretically possible to model global externalities (e.g., the order and positions of ads and so on), they lack an efficient balance of both revenue and social welfare. In this paper, we propose novel auction mechanisms named Neural Multi-slot Auctions (NMA) to tackle the above-mentioned challenges. Specifically, we model the global externalities effectively with a context-aware list-wise prediction module to achieve better performance. We design a list-wise deep rank module to guarantee incentive compatibility in end-to-end learning. Furthermore, we propose an auxiliary loss for social welfare to effectively reduce the decline of social welfare while maximizing revenue. Experiment results on both offline large-scale datasets and online A/B tests demonstrate that NMA obtains higher revenue with balanced social welfare than other existing auction mechanisms (i.e., GSP, DNA, WVCG) in industrial practice, and we have successfully deployed NMA on Meituan food delivery platform.Comment: 10 pages, 3figure

Experimental observation on beach evolution process with presence of artificial submerged sand bar and reef

For observation on the influence mechanism of environmentally and aesthetically friendly artificial submerged sand bars and reefs in a process-based way, a set of experiments was conducted in a 50 m-long flume to reproduce the cross-shore beach morphodynamic process under four irregular wave conditions. The beach behavior is characterized by the scarp (indicating erosion) and the breaker bar (indicating deposition), respectively, and the scarp location can be formulated as a linear equation regarding the natural exponential of the duration time. Overall, main conclusions are: (1) the cross-shore structure of significant wave height and set-up is mainly determined by the artificial reef (AR); (2) the cross-shore distribution of wave skewness, asymmetry, and undertow (indicating shoaling and breaking) is more affected by the artificial submerged sand bar (ASB); (3) the ASB deforms and loses its sand as it attenuates incident waves, which leads to a complex sediment transport pattern; (4) the scarp retreat is related to the beach state, which can be changed by the AR and the ASB; (5) the AR, the ASB, and their combination decrease wave attack on the beach. In conclusion, this study proves positive effects of the AR and the ASB in beach protection through their process-based influences on beach behaviors and beach states for erosive waves

Superior photo-carrier diffusion dynamics in organic-inorganic hybrid perovskites revealed by spatiotemporal conductivity imaging

The outstanding performance of organic-inorganic metal trihalide solar cells benefits from the exceptional photo-physical properties of both electrons and holes in the material. Here, we directly probe the free-carrier dynamics in Cs-doped FAPbI3 thin films by spatiotemporal photoconductivity imaging. Using charge transport layers to selectively quench one type of carriers, we show that the two relaxation times on the order of 1 μs and 10 μs correspond to the lifetimes of electrons and holes in FACsPbI3, respectively. Strikingly, the diffusion map- ping indicates that the difference in electron/hole lifetimes is largely compensated by their disparate mobility. Consequently, the long diffusion lengths (3~5 μm) of both carriers are comparable to each other, a feature closely related to the unique charge trapping and de- trapping processes in hybrid trihalide perovskites. Our results unveil the origin of superior diffusion dynamics in this material, crucially important for solar-cell applications.The research at UT-Austin was primarily supported by the NSF through the Center for Dynamics and Control of Materials, an NSF Materials Research Science and Engineering Center (MRSEC) under Cooperative Agreement DMR-1720595. The authors also acknowledge the use of facilities and instrumentation supported by the NSF MRSEC. K.L. and X.M. acknowledge the support from Welch Foundation Grant F-1814. X. Li acknowledges the support from Welch Foundation Grant F-1662. The tip-scan iMIM setup was supported by the US Army Research Laboratory and the US Army Research Office under Grants W911NF-16-1-0276 and W911NF-17-1-0190. The work at NREL was supported by the US DOE under Contract No. DE-AC36-08GO28308 with Alliance for Sustainable Energy, Limited Liability Company (LLC), the Manager and Operator of the National Renewable Energy Laboratory. K.Z., J.H., X.C., X.W., and Y.Y. acknowledge the support on charge carrier dynamics study from the Center for Hybrid Organic-Inorganic Semiconductors for Energy (CHOISE), an Energy Frontier Research Center funded by the Office of Basic Energy Sciences, Office of Science within the US DOE. F.Z. acknowledges the support on devices fabrication and characterizations from the De-Risking Halide PSCs program of the National Center for Photovoltaics, funded by the US DOE, Office of Energy Efficiency and Renewable Energy, Solar Energy Technologies Office.Center for Dynamics and Control of Material

The Guole Lagerstätte (Guangxi Province, China): Bridging the Furongian Gap of echinoderms

International audienceDuring Cambrian Series 2 and Miaolingian, echinoderms underwent a major diversification leading to a wide palaeobiogeographic distribution and a particularly high morphological disparity, with the appearance of numerous distinct 'body plans' ('classes') in less than 20 Myr (e.g. cinctans, ctenocystoids, edrioasteroids, gogiid and columnal-bearing eocrinoids, helicoplacoids, helicocystids, imbricates, solutans, stylophorans). The Early Ordovician represents a second major burst in echinoderm diversity and disparity, with the onset of several additional clades, including the earliest representatives of the three extant classes Asteroidea, Crinoidea and Ophiuroidea. In marked contrast with these two time intervals yielding abundant and diverse echinoderm assemblages, very few echinoderm remains have been documented so far in the Furongian (Cambrian Stages Paibian-10). This lack of data from the late Cambrian is not unique to echinoderms, but is also observed for most other marine invertebrates. Until recently, few, low diversity Furongian echinoderm assemblages had been reported, mainly from Australia (Chatsworth Limestone), France (Montagne Noire) and the USA (mostly from Nevada and Utah). In the last 15 years, a new major echinoderm Lagerstätte, the Guole Biota, was discovered in the Sandu Formation (Jiangshanian) of Guangxi Province, South China. The sandstones and shales of the Sandu Formation yielded hundreds of extremely well-preserved, fully articulated echinoderms belonging to four distinct echinoderm classes: Edrioasteroidea, Rhombifera, Soluta and Stylophora. Edrioasteroids are rare and represented by the edrioblastoid Cambroblastus guolensis, which is closely related to C. enubilatus from the Chatsworth Limestone (Australia). Rhombiferans are relatively common and consist of the glyptocystitid Sanducystis sinensis, which is morphologically close to Furongian taxa from Australia (Ridersia) and France (Barroubiocystis, Velieuxicystis). The Sandu Formation yielded rare specimens of solutans, all belonging to a new, yet undescribed species, which represents the earliest record of this class outside of Laurentia. Stylophorans are particularly abundant and diverse, with at least two distinct cornute taxa (Drepanocarpos sp. and 'Phyllocystis' jingxiensis) and one mitrate ('Nanocarpus' guoleensis). The earliest hanusiid Drepanocarpos was previously known only from the Furongian of Australia. 'Phyllocystis' jingxiensis is closely related to cornutes from the Tremadocian of Korea (Dongjeom Formation) and Morocco (Fezouata Shale). Finally, 'Nanocarpus' guoleensis is the earliest known mitrate, with clear affinities with younger taxa from the Tremadocian of Korea, France and Morocco. Consequently, the Guole Biota has yielded one of the most diverse (four classes, seven taxa) and best preserved echinoderm assemblage known so far. Taxonomically, it is typical of the low diversity 'rhombiferanstylophoran' assemblages documented worldwide in the late Cambrian. From a palaeobiogeographic point of view, affinities are highest with coeval Australian faunas, although links with other peri-Gondwanan areas are also relatively obvious

Furongian (Jiangshanian) occurrences of radiodonts in Poland and South China and the fossil record of the Hurdiidae

The Furongian period represents an important gap in the fossil record of most groups of non-biomineralizing organisms, owing to a scarcity of Konservat-Lagerstätten of that age. The most significant of these deposits, the Jiangshanian strata of the Sandu Formation near Guole Township (Guangxi, South China), have yielded a moderately abundant, but taxonomically diverse soft-bodied fossil assemblage, which provides rare insights into the evolution of marine life at that time. In this contribution, we report the first discovery of a radiodont fossil from the Guole Konservat-Lagerstätte. The specimen is an incomplete frontal appendage of a possibly new representative of the family Hurdiidae. It is tentatively interpreted as composed of seven podomeres, six of which bearing laminiform endites. The best preserved of these endites is especially long, and it bears short auxiliary spines that greatly vary in size. This is the second occurrence of hurdiids and more generally radiodonts in the Furongian, the first being the external mould of an oral cone from Jiangshanian strata of the Wiśniówka Sandstone Formation in Poland. Restudy of this Polish specimen confirms that it belongs to a hurdiid radiodont and best compares to Peytoia. The family Hurdiidae includes the oldest (basal Cambrian Epoch 2) and youngest (Early Ordovician, possibly Early Devonian) representatives of the Radiodonta and as such, has the longest stratigraphical range of the group. Yet, hurdiids only became prominent components of marine ecosystems during the middle Cambrian (Miaolingian), and their fossil record in younger strata remains limited

The first aglaspidid sensu stricto from the Cambrian of China (Sandu Formation, Guangxi)

Aglaspidids represent an obscure group of lower Palaeozoic arthropods with a patchy biogeographic distribution. Before the recent description of a representative from Tasmania, these arthropods were exclusively known from Laurentia during the late Cambrian. Here we describe a new species, Aglaspella sanduensis sp. nov., from the Furongian of China, confirming that aglaspidids sensu stricto were already widely distributed worldwide by the late Cambrian; this demonstrates that some aglaspidids had great dispersal capabilities. A new diagnosis of the genus Aglaspella is proposed and the species formerly known as Aglaspella eatoni is assigned to a new taxon, Hesselbonia gen. nov