Paleoenvironmental characteristics and organic matter enrichment mechanisms of the upper Ordovician-lower Silurian organic-rich black shales in the Yangtze foreland basin, South China

The Wufeng Formation-Longmaxi Formation (O3w-S1l1) black shales within the Yangtze foreland basin (South China) hold significant potential as unconventional oil and gas resources. However, several challenges, including sluggish sedimentation rates, thin sedimentary layers, and notable homogeneity, hinder a comprehensive grasp of the organic matter enrichment (OME) mechanism within these shales. These challenges impede the exploration of unconventional oil and gas resources. This study aims to identify the O3w-S1l1 black shales in the Weiyuan area through a combined approach of organic and inorganic geochemical analyses. By doing so, it delves into the controlling mechanism behind OME in the black shales of the Yangtze foreland basin. The findings of this research reveal that the O3w-S1l1 black shales primarily consist of sapropelic kerogen and exhibit signs of over-maturation, with TOC content ranging from 0.43% to 8.21%. These shales are classified as organic-rich, mainly composed mixed and siliceous lithofacies. The presence of silica in the shales originates mainly from biogenic sources, and the highest TOC content coincides with a Sixs contribution of around 30% to the total silica content. During the late Katian, a global sea level drop led to an oxic paleoenvironment, transitioning into a euxinic paleoenvironment as sea levels rose in the early Rhuddanian. Notably, TOC content exhibited a significant correlation with paleoceanographic conditions (e.g., V/Cr, Ni/Co) and paleoproductivity levels (e.g., P/Al, Babio), while displaying a negative correlation with paleoclimate conditions (e.g., CIA, C-value), terrigenous detrital input intensity (e.g., Sixs, Ti/Al), and sedimentation rate ((La/Yb)N). Specifically, favourable conditions for OME encompass robust reducing seawater conditions, high paleoproductivity, a humid climate, reduced influx of terrigenous debris, and relatively elevated sedimentation rates. Regional tectonic movements (Guangxi movement) and fluctuations in relative sea levels exert influence over the deposition of O3w-S1l1 black shales. This study provides a valuable case study for exploring and developing shale gas resources within the Yangtze foreland basin

Machine learning models for predicting the risk factor of carotid plaque in cardiovascular disease

IntroductionCardiovascular disease (CVD) is a group of diseases involving the heart or blood vessels and represents a leading cause of death and disability worldwide. Carotid plaque is an important risk factor for CVD that can reflect the severity of atherosclerosis. Accordingly, developing a prediction model for carotid plaque formation is essential to assist in the early prevention and management of CVD.MethodsIn this study, eight machine learning algorithms were established, and their performance in predicting carotid plaque risk was compared. Physical examination data were collected from 4,659 patients and used for model training and validation. The eight predictive models based on machine learning algorithms were optimized using the above dataset and 10-fold cross-validation. The Shapley Additive Explanations (SHAP) tool was used to compute and visualize feature importance. Then, the performance of the models was evaluated according to the area under the receiver operating characteristic curve (AUC), feature importance, accuracy and specificity.ResultsThe experimental results indicated that the XGBoost algorithm outperformed the other machine learning algorithms, with an AUC, accuracy and specificity of 0.808, 0.749 and 0.762, respectively. Moreover, age, smoke, alcohol drink and BMI were the top four predictors of carotid plaque formation. It is feasible to predict carotid plaque risk using machine learning algorithms.ConclusionsThis study indicates that our models can be applied to routine chronic disease management procedures to enable more preemptive, broad-based screening for carotid plaque and improve the prognosis of CVD patients

A Privacy Model for RFID Tag Ownership Transfer

The ownership of RFID tag is often transferred from one owner to another in its life cycle. To address the privacy problem caused by tag ownership transfer, we propose a tag privacy model which captures the adversary’s abilities to get secret information inside readers, to corrupt tags, to authenticate tags, and to observe tag ownership transfer processes. This model gives formal definitions for tag forward privacy and backward privacy and can be used to measure the privacy property of tag ownership transfer scheme. We also present a tag ownership transfer scheme, which is privacy-preserving under the proposed model and satisfies the other common security requirements, in addition to achieving better performance

Ce qui est (mé)connu de l’Acheuléen chinois, avec implications sur les hypothèses de la dispersion précoce des homininés

Le progrès des découvertes effectuées dans les régions livrant des bifaces en Chine fait de l’étude de l’Acheuléen un champ de recherche dynamique au sein du Paléolithique chinois. En donnant le détail de ces développements dans cet article, nous intégrons les dernières réalisations provenant des quatre régions clé pour l’Acheuléen en Chine (à savoir Dingcun, Bose, Luonan et région du Danjiangkou Reservoir). Sur cette base et celle de nos propres observations effectuées sur le matériel de ces quatre régions, nous synthétisons les connaissances de l’Acheuléen chinois et nous soulevons les questions irrésolues jusqu’à présent. Finalement, nous considérons cinq arguments, nous semblant particulièrement pertinents, concernant les origines du techno-complexe acheuléen en Chine. À partir de cet état de la question, nous suggérons que l’hypothèse de la transmission technologique est une explication valable pour l’émergence de la technologie bifaciale chinoise et nous apportons des données qui soutiennent l’idée d’une migration des homininés acheuléens depuis l’ouest vers l’est au début du Paléolithique.Progress in research on the different handaxe-bearing regions of China is making study of the Acheulean a dynamic field in the Chinese Palaeolithic. Given the separate history of these developments, in this paper we integrate the latest achievements in the four key Acheulean regions in China (namely, Dingcun, Bose, Luonan and Danjiangkou Reservoir Region). Based on this, and combined with our own observations of materials from these four regions, we summarize what is currently known about the Chinese Acheulean and propose those questions that are still awaiting resolution. Finally, we consider five arguments that are highly relevant to the origins of the Acheulean techno-complex in China. From this synthesis, we suggest that the technological transmission hypothesis might be a suitable explanation for the emergence of Chinese handaxe technology, and we provide supporting data for the migration of Acheulean hominids from west to east in the Early Palaeolithic period.</p

Evolution of local wrinkles near defects on stiff film/compliant substrate

Disordered wrinkles are widely observed in stiff film deposited onto a thermally expanded polymer when compressive stress exceeds the critical wrinkling stress of the film. Highly ordered wrinkles can be fabricated by introducing regularly arranged patterns on the polymer before deposition. However, the study on the morphological evolution of localized wrinkling patterns near defects on the stiff film/compliant substrate is neglected. In this paper, we show two morphological transitions of the local wrinkles induced by defects on an Au film/PDMS substrate. The observation shows that the straight wrinkles form perpendicularly to the line defects and the radial wrinkles form near spot-like defects. We observe that the extended radial wrinkles tend to split and evolve into branching patterns, this limits the deviation of the local wrinkle wavelength from the equilibrium wrinkle wavelength and causes the wrinkle wavelength to be always maintained in a narrow interval. Because the herringbone patterns have the minimum energy state, the straight and radial wrinkles evolve into herringbone wrinkles spontaneously. The morphological characteristic and evolution mechanism of the local wrinkles are described in detail. The observation may provide some clues to the formation and evolution of some localized wrinkling patterns in nature and multilayer materials

Quantifying the Reduction Intensity of Handaxes with 3D Technology: A Pilot Study on Handaxes in the Danjiangkou Reservoir Region, Central China

<div><p>This paper presents an approach to analyzing the reduction intensity of handaxes with the aid of 3D scanning technology. Two quantitative reduction indices, the Scar Density Index (SDI) and the Flaked Area Index (FAI), are applied to handaxes from the third terrace of the Danjiangkou Reservoir Region (DRR), central China, dated to the Middle Pleistocene. The results show that most of the DRR handaxes in this sample show moderate reduction, which also reflects a least-effort reduction strategy and a generally short use-life for these tools. Detailed examination of the DRR handaxes by sector reveals that the tips generally show the most reduction, while the bases show the least shaping, with cortex often preserved on the base to facilitate handling. While western Acheulean assemblages in this regard are variable, there are many examples of handaxes of varying age with trimming of the bases. We also found no significant differences in the levels of reduction between the two main raw materials, quartz phyllite and trachyte. However, the type of blank used (large flakes versus cobbles) and the type of shaping (bifacial, partly bifacial and unifacial) do play a significant role in the reduction intensity of the DRR handaxes. Finally, a small number of handaxes from the younger (the early Late Pleistocene) second terrace of the DRR was compared with those from the third terrace. The results indicate that there is no technological change in the reduction intensity through time in these two DRR terraces.</p></div

Segmentation of a 3D scanned handaxe (No. 1994, 93) into three proportional sectors.

<p>Segmentation of a 3D scanned handaxe (No. 1994, 93) into three proportional sectors.</p