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مفاهيم جديدة للدبلوماسية الصينية
ناقش الكاتب خلاله مفهوم التدخل الإبداعي في الدبلوماسية الصينية الجديدة وقدم عددا من القضايا والشخصيات التي تجسده-وفقا له-في تاريخ الممارسات الدبلوماسية الصينية منذ انتهاء الحرب الباردة واستخلص من خلالها عددا من المبادئ والمفاهيم المرتبطة بالتدخل الإبداعي وكيفية تطبيقه وقدم أخيرا عددا من الافتراضات التصورية للتدخل الإبداعي ليمتد تأثيره إلى ممارسات المرحلة القادمة للدبلوماسية الصينية. ثم طرح المؤلف عددا من القضايا التي تحمل في ثناياها مفهوم التدخل الإبداعي ومعناه وتجسد رؤية الدبلوماسيين الصينيين وسعة خيالهم في التعامل مع الأزمات وأبرزها قضية الوساطة في ميانمار والتدخل في أزمة دارفور.
BOOK
Crystal structure prediction by combining graph network and optimization algorithm
Crystal structure prediction is a long-standing challenge in condensed matter and chemical science. Here we report a machine-learning approach for crystal structure prediction, in which a graph network (GN) is employed to establish a correlation model between the crystal structure and formation enthalpies at the given database, and an optimization algorithm (OA) is used to accelerate the search for crystal structure with lowest formation enthalpy. The framework of the utilized approach (a database + a GN model + an optimization algorithm) is flexible. We implemented two benchmark databases,
i.e
., the open quantum materials database (OQMD) and Matbench (MatB), and three OAs,
i.e
., random searching (RAS), particle-swarm optimization (PSO) and Bayesian optimization (BO), that can predict crystal structures at a given number of atoms in a periodic cell. The comparative studies show that the GN model trained on MatB combined with BO,
i.e
., GN(MatB)-BO, exhibit the best performance for predicting crystal structures of 29 typical compounds with a computational cost three orders of magnitude less than that required for conventional approaches screening structures through density functional theory calculation. The flexible framework in combination with a materials database, a graph network, and an optimization algorithm may open new avenues for data-driven crystal structural predictions.
Predicting crystal structure prior to experimental synthesis is highly desirable. Here the authors propose a machine-learning framework combining graph network and optimization algorithms for crystal structure prediction, which is about three orders of magnitude faster than DFT-based approach.
Journal Article
الثقة في النظرية : نجاح لنظام التنمية (البديل) الخاص بالصين
جاء هذا الكتاب تحت عنوان «الثقة في النظرية : نجاح لنظام التنمية \"البديل\" الخاص بالصين» وهو من تأليف (مايا غيو) وترجمة عبد الرحمن النجار. يبحث الكتاب في التطور الصيني السريع خلال الستة عقود الماضية، والدور الذي لعبه الحزب الشيوعي الصيني في تحويل الصين إلى دولة اشتراكية حديثة مزدهرة وقوية وديمقراطية ومتطورة ثقافيا ويستكشف ويستكشف فيما إذا كان صعود الصين يهدد نموذج التنمية الغربي وخاصة بعد أن أضحى صعود الصين حقيقة لا جدال فيها. يعتبر هذا الكتاب من أنجح الكتب التي نشرت عن الصين اليوم. فهو يقدم حججا مقنعة حول نهوض الصين. وتستند الآراء المعبر عنها في الكتاب ليس فقط إلى 60 عاما من تاريخ جمهورية الصين الشعبية وإنجازاتها الملحوظة في العقود الثلاثة الماضية، ولكن أيضا على تاريخها الحديث منذ عام 1840، وتاريخها الذي دام 2000 عام كدولة موحدة، وحضارتها ذات ال 5000 سنة. وتعكس المقابلات التي أجرتها المؤلفة \"مايا غيو\" مراقبتها الدقيقة للصين اليوم. إذ تضمنت أشخاصا من دوائر مختلفة، تشمل مجالات خبرتهم السياسة والاقتصاد والمجتمع والوضع الوطني وتاريخ دبلوماسية الحزب الشيوعي الصيني والاستراتيجية العسكرية وإدارة ممتلكات الدولة والرعاية الصحية والأعمال التجارية الخاصة. وتختلف موضوعات المقابلات على نطاق واسع؛ فمن النظم والنظرية والتطوير والإصلاح، إلى نوعية الحياة والاستراتيجية والدبلوماسية وجميع من كان فيها يؤيدون التعلم من الحضارات الإنسانية، ولكنهم يصرون في الوقت نفسه على ضرورة اتخاذ مسار يناسب الصين بدلا من استنساخ النموذج الغربي. يأتي هذا الكتاب من ضمن سلسلة تتألف من ثلاثة كتب وهي : الثقة في المسار : نموذج جديد لقوة صاعدة، الثقة في النظرية : فلسفة الصين لنظام دولي جديد، والثقة في النظام : نجاح نظام التنمية \"البديل\" في الصين. بما يوفر للقارئ مقاربة نظرية وواقعية لمسار الصين ونظريتها ونظامها، ويشرح أسباب ثقة الدولة الصينية في خياراتها.
Book
Structural basis for the recognition of Sonic Hedgehog by human Patched1
The Hedgehog (Hh) signaling pathway is important in embryogenesis; overactivation is associated with cancer. Central to the pathway is the membrane receptor Patched 1 (Ptch1), which indirectly inhibits a G protein–coupled receptor called Smoothened. This inhibition is relieved when Ptch1 binds the secreted protein Hh. Gong et al. report the cryo–electron microscopy structures of human Ptch1 alone and in complex with its Hh ligand at 3.9 and 3.6 Å, respectively. Both structures include two steroid-shaped densities, and mutational analysis indicates that the interaction between Ptch1 and Hh is steroid-dependent. Science , this issue p. eaas8935 The cryo–electron microscopy structure of the human receptor for the regulator of development and regeneration shows steroid dependency. The Hedgehog (Hh) pathway involved in development and regeneration is activated by the extracellular binding of Hh to the membrane receptor Patched (Ptch). We report the structures of human Ptch1 alone and in complex with the N-terminal domain of human Sonic hedgehog (ShhN) at resolutions of 3.9 and 3.6 angstroms, respectively, as determined by cryo–electron microscopy. Ptch1 comprises two interacting extracellular domains, ECD1 and ECD2, and 12 transmembrane segments (TMs), with TMs 2 to 6 constituting the sterol-sensing domain (SSD). Two steroid-shaped densities are resolved in both structures, one enclosed by ECD1/2 and the other in the membrane-facing cavity of the SSD. Structure-guided mutational analysis shows that interaction between ShhN and Ptch1 is steroid-dependent. The structure of a steroid binding–deficient Ptch1 mutant displays pronounced conformational rearrangements.
Journal Article
Structural insights into the assembly and substrate selectivity of human SPT–ORMDL3 complex
Human serine palmitoyltransferase (SPT) complex catalyzes the initial and rate-limiting step in the de novo biosynthesis of all sphingolipids. ORMDLs regulate SPT function, with human ORMDL3 being related to asthma. Here we report three high-resolution cryo-EM structures: the human SPT complex, composed of SPTLC1, SPTLC2 and SPTssa; the SPT–ORMDL3 complex; and the SPT–ORMDL3 complex bound to two substrates, PLP-
l
-serine (PLS) and a non-reactive palmitoyl-CoA analogue. SPTLC1 and SPTLC2 form a dimer of heterodimers as the catalytic core. SPTssa participates in acyl-CoA coordination, thereby stimulating the SPT activity and regulating the substrate selectivity. ORMDL3 is located in the center of the complex, serving to stabilize the SPT assembly. Our structural and biochemical analyses provide a molecular basis for the assembly and substrate selectivity of the SPT and SPT–ORMDL3 complexes, and lay a foundation for mechanistic understanding of sphingolipid homeostasis and for related therapeutic drug development.
Cryo-EM structures of serine palmitoyltransferase complexes mediating a key reaction of sphingolipid biosynthesis elucidate principles of its multimeric assembly, regulation and substrate selectivity
Journal Article
Artificial intelligence in the risk prediction models of cardiovascular disease and development of an independent validation screening tool: a systematic review
Background
A comprehensive overview of artificial intelligence (AI) for cardiovascular disease (CVD) prediction and a screening tool of AI models (AI-Ms) for independent external validation are lacking. This systematic review aims to identify, describe, and appraise AI-Ms of CVD prediction in the general and special populations and develop a new independent validation score (IVS) for AI-Ms replicability evaluation.
Methods
PubMed, Web of Science, Embase, and IEEE library were searched up to July 2021. Data extraction and analysis were performed for the populations, distribution, predictors, algorithms, etc. The risk of bias was evaluated with the prediction risk of bias assessment tool (PROBAST). Subsequently, we designed IVS for model replicability evaluation with five steps in five items, including transparency of algorithms, performance of models, feasibility of reproduction, risk of reproduction, and clinical implication, respectively. The review is registered in PROSPERO (No. CRD42021271789).
Results
In 20,887 screened references, 79 articles (82.5% in 2017–2021) were included, which contained 114 datasets (67 in Europe and North America, but 0 in Africa). We identified 486 AI-Ms, of which the majority were in development (
n
= 380), but none of them had undergone independent external validation. A total of 66 idiographic algorithms were found; however, 36.4% were used only once and only 39.4% over three times. A large number of different predictors (range 5–52,000, median 21) and large-span sample size (range 80–3,660,000, median 4466) were observed. All models were at high risk of bias according to PROBAST, primarily due to the incorrect use of statistical methods. IVS analysis confirmed only 10 models as “recommended”; however, 281 and 187 were “not recommended” and “warning,” respectively.
Conclusion
AI has led the digital revolution in the field of CVD prediction, but is still in the early stage of development as the defects of research design, report, and evaluation systems. The IVS we developed may contribute to independent external validation and the development of this field.
Journal Article
MoS2-Decorated/Integrated Carbon Fiber: Phase Engineering Well-Regulated Microwave Absorber
HighlightsA facile one‐step hydrothermal method for producing gram‐scale 1T@2H-MoS2 by imbedding the guest molecules and ions was developed.The influence of different MoS2 phase for electromagnetic absorbing properties was explored by analyzing electromagnetic parameters of 1T/2H MoS2 and 2H MoS2 with 50%, 40%, 30%, 20%, 15%, and 10% filler loading.Taking the advantage of 1T/2H MoS2, the flexible CF@1T/2H MoS2 was also synthesized to mind the request of flexible portable microwave absorption electronic devices.Phase engineering is an important strategy to modulate the electronic structure of molybdenum disulfide (MoS2). MoS2-based composites are usually used for the electromagnetic wave (EMW) absorber, but the effect of different phases on the EMW absorbing performance, such as 1T and 2H phase, is still not studied. In this work, micro-1T/2H MoS2 is achieved via a facile one-step hydrothermal route, in which the 1T phase is induced by the intercalation of guest molecules and ions. The EMW absorption mechanism of single MoS2 is revealed by presenting a comparative study between 1T/2H MoS2 and 2H MoS2. As a result, 1T/2H MoS2 with the matrix loading of 15% exhibits excellent microwave absorption property than 2H MoS2. Furthermore, taking the advantage of 1T/2H MoS2, a flexible EMW absorbers that ultrathin 1T/2H MoS2 grown on the carbon fiber also performs outstanding performance only with the matrix loading of 5%. This work offers necessary reference to improve microwave absorption performance by phase engineering and design a new type of flexible electromagnetic wave absorption material to apply for the portable microwave absorption electronic devices.
Journal Article
Interleukin-6: A Novel Target for Cardio-Cerebrovascular Diseases
Cardio-Cerebrovascular Disease is a collective term for cardiovascular disease and cerebrovascular disease, being a serious threat to human health. A growing number of studies have proved that the content of inflammatory factors or mediators determines the stability of vascular plaque and the incidence of cardio-cerebrovascular event, and involves in the process of Cardio-Cerebrovascular Diseases. Interleukin-6 is a widely used cytokine that causes inflammation and oxidative stress, which would further result in cardiac and cerebral injury. The increased expression of interleukin-6 is closely related to atherosclerosis, myocardial infarction, heart failure and ischemic stroke. It is a key risk factor for these diseases by triggering inflammatory reaction and inducing other molecules release. Therefore, interleukin-6 may become a potential target for Cardio-Cerebrovascular Diseases in the future. This paper is aimed to discuss the expression changes and pathological mechanisms of interleukin-6 in Cardio-Cerebrovascular Diseases, and to provide a novel strategy for the prevention and treatment of Cardio-Cerebrovascular Diseases.
Journal Article
Constructing realistic effective spin Hamiltonians with machine learning approaches
The effective Hamiltonian method has recently received considerable attention due to its power to deal with finite-temperature problems and large-scale systems. In this work, we put forward a machine learning (ML) approach to generate realistic effective Hamiltonians. In order to find out the important interactions among many possible terms, we propose some new techniques. In particular, we suggest a new criterion to select models with less parameters using a penalty factor instead of the commonly-adopted additional penalty term, and we improve the efficiency of variable selection algorithms by estimating the importance of each possible parameter by its relative uncertainty and the error induced in the parameter reduction. We also employ a testing set and optionally a validation set to help prevent over-fitting problems. To verify the reliability and usefulness of our approach, we take two-dimensional MnO and three-dimensional TbMnO3 as examples. In the case of TbMnO3, our approach not only reproduces the known results that the Heisenberg, biquadratic, and ring exchange interactions are the major spin interactions, but also finds out that the next most important spin interactions are three-body fourth-order interactions. In both cases, we obtain effective spin Hamiltonians with high fitting accuracy. These tests suggest that our ML approach is powerful for identifying the effective spin Hamiltonians. Our ML approach is general so that it can be adopted to construct other effective Hamiltonians.
Journal Article
Structural basis of substrate recognition and translocation by human ABCA4
Human ATP-binding cassette (ABC) subfamily A (ABCA) transporters mediate the transport of various lipid compounds across the membrane. Mutations in human ABCA transporters have been described to cause severe hereditary disorders associated with impaired lipid transport. However, little is known about the mechanistic details of substrate recognition and translocation by ABCA transporters. Here, we present three cryo-EM structures of human ABCA4, a retina-specific ABCA transporter, in distinct functional states at resolutions of 3.3–3.4 Å. In the nucleotide-free state, the two transmembrane domains (TMDs) exhibit a lateral-opening conformation, allowing the lateral entry of substrate from the lipid bilayer. The N-retinylidene-phosphatidylethanolamine (NRPE), the physiological lipid substrate of ABCA4, is sandwiched between the two TMDs in the luminal leaflet and is further stabilized by an extended loop from extracellular domain 1. In the ATP-bound state, the two TMDs display a closed conformation, which precludes the substrate binding. Our study provides a molecular basis to understand the mechanism of ABCA4-mediated NRPE recognition and translocation, and suggests a common ‘lateral access and extrusion’ mechanism for ABCA-mediated lipid transport.
Here, cryo-EM structures of human retinal ABCA4 transporter, either in apo state, in complex with ATP or with the physiological lipid substrate N-retinylidene-phosphatidylethanolamine (NRPE), reveal lateral opening, substrate recognition and suggest ‘lateral access and extrusion’ mechanism for ABCA-mediated lipid transport.
Journal Article