37 research outputs found
AdaptDHM: Adaptive Distribution Hierarchical Model for Multi-Domain CTR Prediction
Large-scale commercial platforms usually involve numerous business domains
for diverse business strategies and expect their recommendation systems to
provide click-through rate (CTR) predictions for multiple domains
simultaneously. Existing promising and widely-used multi-domain models discover
domain relationships by explicitly constructing domain-specific networks, but
the computation and memory boost significantly with the increase of domains. To
reduce computational complexity, manually grouping domains with particular
business strategies is common in industrial applications. However, this
pre-defined data partitioning way heavily relies on prior knowledge, and it may
neglect the underlying data distribution of each domain, hence limiting the
model's representation capability. Regarding the above issues, we propose an
elegant and flexible multi-distribution modeling paradigm, named Adaptive
Distribution Hierarchical Model (AdaptDHM), which is an end-to-end optimization
hierarchical structure consisting of a clustering process and classification
process. Specifically, we design a distribution adaptation module with a
customized dynamic routing mechanism. Instead of introducing prior knowledge
for pre-defined data allocation, this routing algorithm adaptively provides a
distribution coefficient for each sample to determine which cluster it belongs
to. Each cluster corresponds to a particular distribution so that the model can
sufficiently capture the commonalities and distinctions between these distinct
clusters. Extensive experiments on both public and large-scale Alibaba
industrial datasets verify the effectiveness and efficiency of AdaptDHM: Our
model achieves impressive prediction accuracy and its time cost during the
training stage is more than 50% less than that of other models
Diachronous end-Permian terrestrial ecosystem collapse with its origin in wildfires
The Permian-Triassic Mass Extinction (PTME) is the greatest biodiversity crisis in Earth history and while the marine crisis is increasingly well constrained, the timing and cause(s) of terrestrial losses remain poorly understood. There have been suggestions that the End-Permian Terrestrial Collapse (EPTC) pre-dated, was synchronous with or post-dated the marine crisis, or even occurred asynchronously in different regions. We address these conflicting interpretations through a detailed geochemical study of a terrestrial sequence in the Liujiang Coalfield on the North China Plate (NCP) in which we apply zircon U-Pb dating of tuffaceous claystone, kerogen identification, and analysis of organic carbon isotopic composition (δ13Corg), total organic carbon (TOC), continental weathering (via the chemical index of alteration; CIA) and Ni concentrations. Our study constrains the Permian-Triassic boundary (PTB) near the base of bed 20 in our sequence at approximately 251.9 ± 1.1 Ma, immediately above a Ni anomaly also known from other terrestrial sequences and the marine PTME. Organic carbon isotope chemostratigraphy together with evidence for algal blooms and the presence of mudstone clasts suggests that the onset of the EPTC in the NCP was synchronous with the crisis in low latitudes (e.g., South China), but was about 310 kyr later than the EPTC in higher southerly latitudes (e.g., Australia). The EPTC predates the marine PTME. Kerogen macerals suggest that a phase of increased wildfire was sustained from the onset of the EPTC in the NCP until the marine PTME interval, implicating wildfire as a major driver of the EPTC (at least in low latitudes) that, in turn, had devastating consequences for the marine realm
OPT-GAN: Black-Box Global Optimization via Generative Adversarial Nets
Black-box optimization (BBO) algorithms are concerned with finding the best
solutions for problems with missing analytical details. Most classical methods
for such problems are based on strong and fixed a priori assumptions, such as
Gaussianity. However, the complex real-world problems, especially when the
global optimum is desired, could be very far from the a priori assumptions
because of their diversities, causing unexpected obstacles to these methods. In
this study, we propose a generative adversarial net-based broad-spectrum global
optimizer (OPT-GAN) which estimates the distribution of optimum gradually, with
strategies to balance exploration-exploitation trade-off. It has potential to
better adapt to the regularity and structure of diversified landscapes than
other methods with fixed prior, e.g. Gaussian assumption or separability.
Experiments conducted on BBO benchmarking problems and several other benchmarks
with diversified landscapes exhibit that OPT-GAN outperforms other traditional
and neural net-based BBO algorithms.Comment: M. Lu and S. Ning contribute equally. Submitted to IEEE transactions
on Neural Networks and Learning System
Middle Jurassic terrestrial environmental and floral changes linked to volcanism: Evidence from the Qinghai Tibet Plateau, China
The breakup of Pangaea and the rapid opening of the Ligurian and Central Atlantic oceans during the Middle Jurassic resulted in widespread volcanism accompanied by significant shifts in global environments, climates, and floras. Although major volcanism is a plausible driver of such global changes, linking these phenomena in the Middle Jurassic is hindered by a lack of detailed sedimentary records from which to evaluate cause and effect. Here, we link Middle Jurassic environmental, climatic, and floral changes with volcanism using records from the Dameigou section of the Qaidam Basin on the Qinghai-Tibet Plateau. High-resolution chemostratigraphic (δ13Corg patterns) and biostratigraphic (palynological fossils) data reveal three negative organic carbon isotope excursions (NCIE) at the Aalenian-Bajocian boundary, the Bajocian-Bathonian boundary, and in the middle of the Callovian, respectively. The first two NCIEs (NCIE-I and NCIE-II) were accompanied by relatively warm and humid climatic conditions and coal accumulation. In contrast, the third NCIE (NCIE-III) was accompanied by warm but dry climatic conditions, a decrease in coal accumulation, a decline in plant diversity, the significant decline in fern spore diversity and abundance, and a rapid increase in the abundance of Classopollis pollen (based on petrological, palynological, PCA, Hydrophyte/Xerophyte ratio, and nMDS data). Four sedimentary mercury anomalies (Hg/Al spikes) have temporal coincidence with the three NCIEs and climate warming events, suggesting a volcanic origin for these. We suggest that volcanism was a key driver of Middle Jurassic change, with major pulses releasing large amounts of CO2 and Hg into the atmosphere, resulting in Hg loading, NCIEs, climatic warming, and floral changes in terrestrial strata. Our multi-proxy study provides new insights into the links between volcanism and terrestrial environmental, climatic, and floral changes during the Middle Jurassic
Robust Representation Learning for Unified Online Top-K Recommendation
In large-scale industrial e-commerce, the efficiency of an online
recommendation system is crucial in delivering highly relevant item/content
advertising that caters to diverse business scenarios. However, most existing
studies focus solely on item advertising, neglecting the significance of
content advertising. This oversight results in inconsistencies within the
multi-entity structure and unfair retrieval. Furthermore, the challenge of
retrieving top-k advertisements from multi-entity advertisements across
different domains adds to the complexity. Recent research proves that
user-entity behaviors within different domains exhibit characteristics of
differentiation and homogeneity. Therefore, the multi-domain matching models
typically rely on the hybrid-experts framework with domain-invariant and
domain-specific representations. Unfortunately, most approaches primarily focus
on optimizing the combination mode of different experts, failing to address the
inherent difficulty in optimizing the expert modules themselves. The existence
of redundant information across different domains introduces interference and
competition among experts, while the distinct learning objectives of each
domain lead to varying optimization challenges among experts. To tackle these
issues, we propose robust representation learning for the unified online top-k
recommendation. Our approach constructs unified modeling in entity space to
ensure data fairness. The robust representation learning employs domain
adversarial learning and multi-view wasserstein distribution learning to learn
robust representations. Moreover, the proposed method balances conflicting
objectives through the homoscedastic uncertainty weights and orthogonality
constraints. Various experiments validate the effectiveness and rationality of
our proposed method, which has been successfully deployed online to serve real
business scenarios.Comment: 14 pages, 6 figures, submitted to ICD
Volcanically-induced floral changes across the Triassic-Jurassic (T-J) transition
The End-Triassic Mass Extinction (ETME) saw the catastrophic loss of ca. 50% of marine genera temporally associated with emplacement of the Central Atlantic Magmatic Province (CAMP). However, the effects of the ETME on land is a controversial topic. Evaluation of the disparate cause(s) and effects of the extinction requires additional, detailed terrestrial records of these events. Here, we present a multidisciplinary record of volcanism and environmental change from an expanded Triassic-Jurassic (T-J) transition preserved in lacustrine sediments from the Jiyuan Basin, North China. High-resolution chemostratigraphy, palynological, kerogen, and sedimentological data reveal that terrestrial conditions responded to and were defined by large-scale volcanism. The record of sedimentary mercury reveals two discrete CAMP eruptive phases during the T-J transition. Each of these can be correlated with large, negative C isotope excursions (CIE-I of -4.7 ‰; CIE-II of -2.9 ‰), significantly reduced plant diversity (with ca. 45% and 44% generic losses respectively), enhanced wildfire (marked by increased fusinite or charcoal content), and major climatic shifts towards drier and hotter conditions (indicated by the occurrence of calcareous nodules, increased Classopollis pollen content, and PCA analysis). Our results show that CAMP eruptions may have followed a bimodal eruptive model and demonstrate the powerful ability of large-scale volcanism to alter the global C cycle and profoundly affect the climate, in turn leading to enhanced wildfires and a collapse in land plant diversity during the T-J transition
Four volcanically driven climatic perturbations led to enhanced continental weathering during the Late Triassic Carnian Pluvial Episode
The arid climate of the Late Triassic was interrupted by a particularly humid episode known as the Carnian Pluvial Episode (CPE; ca. 234–232 million years ago). The CPE is often linked to eruptions in the Wrangellia Large Igneous Province (LIP), and is assumed to have led to global warming, enhanced weathering, water deoxygenation, and biotic changes. However, direct evidence for a temporal link between volcanic activity and chemical weathering has not yet been established due to the lack of comprehensive records across the CPE. In this study, geochemical and mineralogical analyses are applied to a lacustrine stratigraphic succession of the Jiyuan Basin (North China) that captures the CPE in high resolution. We identify four distinct pulses of enhanced continental chemical weathering characterized by elevated Chemical Index of Alteration values and kaolinite contents. These peaks in continental weathering coincide with Hg/TOC enrichments and negative organic carbon isotope excursions that mark four short (~400 kyr) but intense pulses of Wrangellia LIP volcanism. In combination with signs of increased humidity, our findings provide direct and independent evidence that Wrangellia LIP eruptions significantly altered CPE chemical weathering rates in response to global warming and wetting. The lake experienced eutrophication and water deoxygenation after each volcanic pulse but the swift recovery of carbon isotopes suggests that the system rapidly returned to conditions prior to the volcanic perturbation. Organic carbon burial facilitated by widespread dysoxic and anoxic waters, and CO2 consumption via enhanced weathering likely played crucial roles in the rapid climatic recovery after each volcanic pulse