Counterfactual Estimation and Optimization of Click Metrics for Search Engines

Optimizing an interactive system against a predefined online metric is particularly challenging, when the metric is computed from user feedback such as clicks and payments. The key challenge is the counterfactual nature: in the case of Web search, any change to a component of the search engine may result in a different search result page for the same query, but we normally cannot infer reliably from search log how users would react to the new result page. Consequently, it appears impossible to accurately estimate online metrics that depend on user feedback, unless the new engine is run to serve users and compared with a baseline in an A/B test. This approach, while valid and successful, is unfortunately expensive and time-consuming. In this paper, we propose to address this problem using causal inference techniques, under the contextual-bandit framework. This approach effectively allows one to run (potentially infinitely) many A/B tests offline from search log, making it possible to estimate and optimize online metrics quickly and inexpensively. Focusing on an important component in a commercial search engine, we show how these ideas can be instantiated and applied, and obtain very promising results that suggest the wide applicability of these techniques

Study on inversion of coal seam temperature in mining area --Pingshuo mining area of Shanxi Province

Landsat 8 is widely used in the extraction of surface temperature, but the data of surface temperature and abnormal area in Pingshuo mining area is vacant based on Landsat 8 in recent years, and there is no standard optimal algorithm to follow. In order to explore the possibility of underground coal fire in Pingshuo mining area of Shanxi Province in the future, based on the Landsat 8 satellite data, the temperature inversion method is used to observe the temperature distribution of the mining area, and three commonly used algorithms of temperature inversion processing are used to compare and analyze the SC algorithm as the best data processing method. The artificial threshold method and NDVI threshold method are used to extract the temperature anomaly area and vegetation coverage area, and calculate the area and proportion of coal fire potential area. According to a series of the data and result charts analysis, it shows that: the highest vegetation index of Pingshuo mining area is 0.79, the vegetation coverage is low, and the surface temperature is more than 41.44 ℃, which may lead to the spontaneous combustion of underground coal mines. However, the area prone to underground coal fires is small and controllable. According to the area of potential coal fires in the mining area, the local relevant departments can take relevant measures to prevent coal fire through the distribution map of potential coal fires

Soil acidification reduces the effects of short-term nutrient enrichment on plant and soil biota and their interactions in grasslands

Soil nitrogen (N) and phosphorus (P) contents, and soil acidification have greatly increased in grassland ecosystems due to increased industrial and agricultural activities. As major environmental and economic concerns worldwide, nutrient enrichment and soil acidification can lead to substantial changes in the diversity and structure of plant and soil communities. Although the separate effects of N and P enrichment on soil food webs have been assessed across different ecosystems, the combined effects of N and P enrichment on multiple trophic levels in soil food webs have not been studied in semiarid grasslands experiencing soil acidification. Here we conducted a short-term N and P enrichment experiment in non-acidified and acidified soil in a semiarid grassland on the Mongolian Plateau. We found that net primary productivity was not affected by N or P enrichment alone in either non-acidified or acidified soil, but was increased by combined N and P enrichment in both non-acidified and acidified soil. Nutrient enrichment decreased the biomass of most microbial groups in non-acidified soil (the decrease tended to be greatest with combined N and P enrichment) but not in acidified soil, and did not affect most soil nematode variables in non-acidified or acidified soil. Nutrient enrichment also changed plant and microbial community structure in non-acidified but not in acidified soil, and had no effect on nematode community structure in non-acidified or acidified soil. These results indicate that the responses to short-term nutrient enrichment were weaker for higher trophic groups (nematodes) than for lower trophic groups (microorganisms) and primary producers (plants). The findings increase our understanding of the effects of nutrient enrichment on multiple trophic levels of soil food webs, and highlight that soil acidification, as an anthropogenic stressor, reduced the responses of plants and soil food webs to nutrient enrichment and weakened plant-soil interactions

Patterns of brachiopod faunal and body-size changes across the Permian-Triassic boundary: Evidence from the Daoduishan section in Meishan area, South China

New analysis of Permian-Triassic brachiopod assemblages and body-size changes in South China provides insights into the process of the environmental crisis in the lead up to the end-Permian mass extinction. The recently discovered Daoduishan section of South China can be considered as an important auxiliary section for the study of brachiopods at the Meishan Section D of South China, the GSSP of the Permian-Triassic Boundary (PTB). This paper studied changes of the brachiopod assemblages and body sizes through the upper part of the Changxing Formation and basal Yinkeng Formation of Daoduishan. The results show that significant changes of brachiopod assemblages took place between Beds 24e and 26. Brachiopods?Prelissorhynchia sp. and Paracruirithyris pygmaea are the dominators in Beds 14-24e, while Tethyochonetes pigmaea and Paryphella spp. are the dominators in Beds 26-29. Body sizes of brachiopods significantly decreased between Beds 24e and 26 and then maintained smaller means in Beds 27-29. Studies of brachiopod morphological features indicate both Tethyochonetes and Paryphella had advantageous adaptations enabling them to copy with living in an anoxic/dysoxic and/or low-productivity environment during the Permian-Triassic crisis

Effects of root exudate stoichiometry on CO2 emission from paddy soil

Root exudates are a labile source of carbon (C) for microorganisms that can lead to increased CO2 emission. Root exudates can vary in C:N stoichiometric ratio and their impact on microbially driven soil organic matter (SOM) turnover in paddy soils still remains unclear. The objective was to explore the underlying mechanisms involved in SOM decomposition due to root exudate (artificial) addition with three different C:N ratios (10, 20, and 40) during 45 days incubation. Different root exudates C:N ratios were obtained by adding mineral N and exudate components (glucose, oxalic acid, and glutamate) to paddy soil. N-only addition decreased dissolved organic C to limit CO2 emissions, which is an indicative of C sequestration. Conversely, simulated C:N stoichiometric ratios of root exudates significantly increased both microbial activity and metabolism without altering the microbial biomass C:N ratio. However, soil available dissolved organic C to NH4+ ratio decreased by exudates addition. The stoichiometric ratio of key C and N compound degrading enzymes activities increased only with C:N = 10 and remained unchanged with exudates C:N = 20 and 40. The qCO2 values increased with decreasing N-containing compounds in root exudates (i.e. highest CO2 emission was observed under C:N = 40 exudates addition). The results suggest that increasing exudates C:N ratio intensify CO2 emission due to high microbial N demand. Overall result show that root exudates C:N ratio and soil available N co-regulate on CO2 emission, which was controlled by microbial and potential extracellular enzyme activities

Petrogenesis of the Late Jurassic Granodiorite and Its Implications for Tectonomagmatic Evolution in the Nuocang District, Western Gangdeses

The Gangdese magmatic rocks of the southern Lhasa terrane, are generally thought to be an important window to witness the formation and evolution of the Neo-Tethys oceanic opening, subduction, and closure, and India-Eurasian continental collision. We investigated a new occurrence of granodiorite in the Nuocang district of western Gangdese, southern Lhasa terrane, and conducted a series of analyses on their petrology, chronology, and geochemistry. The Nuocang granodiorites have the zircon U-Pb ages of 151–154 Ma, which suggest that Late Jurassic granitoids are present in the western Gangdese of southern Lhasa terrane. They are relatively high in SiO2, Al2O3, low K2O, Na2O, and Sr/Y ratios, enrichments of LILE and LREE, and depletion of HFSE, with the positive correlation between Rb and Th, and negative correlations between SiO2 and P2O5, Rb, and Y, showing the features of I-type granites. The relatively high (87Sr/86Sr)i values from 0.712231 to 0.712619, low εNd(t) values from −9.56 to −8.99, together with the negative εHf(t) values from −10.8 to −5.0 (mean value −8.9) suggested that the Nuocang granodiorites probably sourced from the partial melting of the ancient Lhasa terrane, with parts of mantle materials involving in. Combined with the previous geochronology and geochemical data of Mesozoic magmas in the Gangdese belt, as well as the Late Jurassic granodiorite, in this paper, we propose that the Nuocang granodiorites formed in a continental margin arc environment triggered by the northward subduction of Neo−Tethys oceanic crust

Petrogenesis of the Late Jurassic Granodiorite and Its Implications for Tectonomagmatic Evolution in the Nuocang District, Western Gangdeses

The Gangdese magmatic rocks of the southern Lhasa terrane, are generally thought to be an important window to witness the formation and evolution of the Neo-Tethys oceanic opening, subduction, and closure, and India-Eurasian continental collision. We investigated a new occurrence of granodiorite in the Nuocang district of western Gangdese, southern Lhasa terrane, and conducted a series of analyses on their petrology, chronology, and geochemistry. The Nuocang granodiorites have the zircon U-Pb ages of 151–154 Ma, which suggest that Late Jurassic granitoids are present in the western Gangdese of southern Lhasa terrane. They are relatively high in SiO2, Al2O3, low K2O, Na2O, and Sr/Y ratios, enrichments of LILE and LREE, and depletion of HFSE, with the positive correlation between Rb and Th, and negative correlations between SiO2 and P2O5, Rb, and Y, showing the features of I-type granites. The relatively high (87Sr/86Sr)i values from 0.712231 to 0.712619, low εNd(t) values from −9.56 to −8.99, together with the negative εHf(t) values from −10.8 to −5.0 (mean value −8.9) suggested that the Nuocang granodiorites probably sourced from the partial melting of the ancient Lhasa terrane, with parts of mantle materials involving in. Combined with the previous geochronology and geochemical data of Mesozoic magmas in the Gangdese belt, as well as the Late Jurassic granodiorite, in this paper, we propose that the Nuocang granodiorites formed in a continental margin arc environment triggered by the northward subduction of Neo−Tethys oceanic crust