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Eguchi–Hanson Singularities in U(2)-Invariant Ricci Flow

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Peking Mathematical Journal 2023年第1期6卷 1-141页

作者： alexander Appleton Department of Mathematics UC BerkeleyBerkeleyCA 94720USA

We show that a Ricci flow in four dimensions can develop singularities modeled on the Eguchi–Hanson *** particular,we prove that starting from a class of asymptotically cylindrical U(2)-invariant initial metrics on T S^(2),a Type II singularity modeled on the Eguchi–Hanson space develops in finite ***,we show that for these Ricci flows the only possible blow-up limits are(i)the Eguchi–Hanson space,(ii)the flat R4/Z2 orbifold,(iii)the 4d Bryant soliton quotiented by Z2,and(iv)the shrinking cylinder R×RP^(3).As a byproduct of our work,we also prove the existence of a new family of Type II singularities caused by the collapse of a two-sphere of self-intersection|k|≥3.

关键词： Ricci Flow Eguchi–Hanson metric Singularity model Four dimensional Blow-up

Mapping the spatial and temporal patterns of fallow land in mountainous regions of China

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International Journal of Digital Earth 2022年第1期15卷 2148-2167页

作者： Wen Song alexander V.Prishchepov Wei Song Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijingPeople’s Republic of China School of Geomatics and Urban Spatial Informatics Beijing University of Civil Engineering and ArchitectureBeijingPeople’s Republic of China Department of Geosciences and Natural Resource Management (IGN) University of CopenhagenKøbenhavn KDenmark Department of Theoretical Cybernetics and Applied Mathematics Altai State UniversityBarnaulRussia

The rapid growth of the global population has resulted in a continuous increase in cropland intensity and a shortening of the fallow period as part of the cropland rotation ***,there is a lack of systematic knowledge on the extent of fallow lands,particularly in complex landscapes,such as the mountainous regions of *** fill this knowledge gap,taking Yuanyang County(YYC),Yunnan Province,China,as a case study,we tested a method to identify the spatial-temporal distribution of fallow land by mapping cropland with Landsat *** overall accuracy of land cover classification,including cropland,ranged between 90.1%and 95.8%from 1998 to *** average accuracy of fallow plots was 75.7%from 2001 to *** annual fallow rate varied between 8.3%and 54.3%,with an average of 20.7%.Kernel density estimated with the probability density function showed that fallow varied between 5 and 13 blocks per km2,gradually decreasing from the central area to the *** elevation,the low value of regional domestic products,and the increased distance to rural settlements were closely related to the higher proportions of fallow *** approach presented here can be applied to map fallow land in other regions.

关键词： Remote sensing fallow land kernel density time series China

Fast Bayesian optimization of Needle-in-a-Haystack problems using zooming memory-based initialization (ZoMBI)

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npj Computational Materials 2023年第1期9卷 1543-1555页

作者： alexander E.Siemenn Zekun Ren Qianxiao Li Tonio Buonassisi Department of Mechanical Engineering Massachusetts Institute of TechnologyCambridgeMAUSA Department of Electrical and Computer Engineering Singapore-MIT Alliance for Research and TechnologySingaporeSingapore Xinterra SingaporeSingapore Department of Mathematics National University of SingaporeSingaporeSingapore Institute for Functional Intelligent Materials National University of SingaporeSingaporeSingapore

Needle-in-a-Haystack problems exist across a wide range of applications including rare disease prediction,ecological resource management,fraud detection,and material property optimization.A Needle-in-a-Haystack problem arises when there is an extreme imbalance of optimum conditions relative to the size of the ***,current state-of-the-art optimization algorithms are not designed with the capabilities to find solutions to these challenging multidimensional Needle-in-a-Haystack problems,resulting in slow convergence or pigeonholing into a local *** this paper,we present a Zooming Memory-Based Initialization algorithm,entitled ZoMBI,that builds on conventional Bayesian optimization principles to quickly and efficiently optimize Needle-in-a-Haystack problems in both less time and fewer *** ZoMBI algorithm demonstrates compute time speed-ups of 400×compared to traditional Bayesian optimization as well as efficiently discovering optima in under 100 experiments that are up to 3×more highly optimized than those discovered by similar methods.

关键词： optimization problems extreme

Attentiveness to Early Warning Drought Information:Implications for Policy Support and Climate Risk Reduction in Ghana

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International Journal of Disaster Risk Science 2022年第1期13卷 25-37页

作者： Peter Dok Tindan Divine Odame Appiah alexander Yao Segbefia Department of Geography and Rural Development Kwame Nkrumah University of Science and TechnologyKumasiAshanti RegionGhana

Successful drought planning is dependent on the generation of timely and accurate early warning *** there is little evidence to explain the extent to which crop farmers pay attention to and assimilate early warning drought information that aids in the policy formulation in support of drought risk reduction.A socioecological survey,using a structured questionnaire administered to 426 crop farming households,was carried out in the Talensi District of the Upper East Region,*** data analytic techniques used were frequency tables,relative importance index,and multinomial logistics embedded in SPSS v.20 *** results show that crop farmers predominantly rely on agricultural extension officers for early warning drought information,with an estimated 78% of them paying little to very much attention to the *** likelihood ratio Chi-square test showed that there is a significant improvement in fit as X^(2)(20)=96.792,p<*** status,average monthly income,and age were the significant predictors for crop farmers paying no attention at all to early warning drought information,while household status was the only significant factor among those paying a little *** drive to build a climate-resilient society with effective early warning centers across Ghana will receive 60% lower support from crop farmers paying no to a little attention as compared to farmers paying very much attention to early warning drought *** stakeholder engagements should be carried out to harness inclusive support from crop farmers to build a climate-resilient society in Ghana.

关键词： Attentiveness to early drought warning Climate risk Drought risk reduction Ghana

eXawatt Center for Extreme Light Studies

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High Power Laser Science and Engineering 2023年第6期11卷 101-129页

作者： Efim Khazanov Andrey Shaykin Igor Kostyukov Vladislav Ginzburg Ivan Mukhin Ivan Yakovlev alexander Soloviev Ivan Kuznetsov Sergey Mironov Artem Korzhimanov Denis Bulanov Ilya Shaikin Anton Kochetkov Alexey Kuzmin Mikhail Martyanov Vladimir Lozhkarev Mikhail Starodubtsev alexander Litvak alexander Sergeev Gaponov-Grekhov Institute of Applied Physics of the Russian Academy of Sciences Nizhny Novgorod 603950Russia

The eXawatt Center for Extreme Light Studies project aimed to create a large scientific infrastructure based on lasers with giant peak *** project relies on the significant progress achieved in the last *** planned infrastructure will incorporate a unique light source with a pulse power of 600 PW using optical parametric chirped pulse amplification in large-aperture KD_(2)PO_(4),deuterated potassium dihydrogen phosphate *** interaction of such laser radiation with matter represents a completely new fundamental *** direct study of the space-time structure of vacuums and other unknown phenomena at the frontier of high-energy physics and the physics of superstrong fields will be *** applications will include the development of compact particle accelerators,the generation of ultrashort pulses of hard X-ray and gamma radiation for material science enabling one to probe material samples with unprecedented spatial and temporal resolution,the development of new radiation and particle sources,*** paper is translation from Russian[Kvantovaya Elektronika 53,95(2023)].

关键词： high-power femtosecond lasers interaction of ultrarelativistic field with matter

Asymmetric reconstruction of the aquareovirus core at near-atomic resolution and mechanism of transcription initiation

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Protein & Cell 2023年第7期14卷 546-550页

作者： alexander Stevens Yanxiang Cui Sakar Shivakoti Hong Zhou Department of Microbiology Immunology and Molecular GeneticsUniversity of CalifomiaLos Angeles(UCLA)609 Charles E Young Dr ELos AngelesCA 90095USA California NanoSystems Institute UCLA570 Westwood Plaza Building 114/Mail Code:722710Los AngelesCA 90095USA Department of Chemistry and Biochemistry UCLA607 Charles E.Young Drive East|Box 951569Los AngelesCA 90095-1569USA

Dear Editor,Aquareovirus(ARV,Reoviridae)causes hemorrhagic disease in the economically important golden shiner and grass carp of America and China,respectively(Nason et al.,2000;Fang et al.,2005).Reoviridae members are characterized by endogenous transcription of their multipartite genomes within capsids of 1-3 layers and are further classified based on the presence(Spinareovirinae subfamily,9 genera)or absence(Sedoreovirinae subfamily,6 genera)of mRNA-capping turrets along the innermost layer(King et al.,2012).

关键词： mechanism endogenous reovirus

RED WoLF hybrid energy storage system: Algorithm case study and green competition between storage heaters and heat pump

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Energy and AI 2023年第4期14卷 383-397页

作者： alexander Alexandrovich Shukhobodskiy Aleksandr Zaitcev Giuseppe Colantuono School of Built Environment Engineering and ComputingLeeds Beckett UniversityLeedsLS13HEUK Watt Wolf Limited 188-192 CommonsideBatleyEnglandWF176EBUK

Green house gases reduction is critical in current climate emergency and was declared as major target by United *** manuscript proposes the progressive adaptive recursive multi threshold control strategy for hybrid energy storage system that combines thermal storage reservoirs,heat pumps,storage heaters,photovoltaic array and a *** newest control strategy is tested in numerical experiment against primal dual simplex optimisation method as benchmark and previous iterations of RED WoLF threshold *** proposed algorithm allows improvement in reduction of CO_(2) emissions by 9%comparatively to RED WoLF double threshold approach and by 26%comparatively to RED WoLF single threshold ***,the proposed technique is at least 100 times faster than linear optimisation,making the algorithm applicable to edge *** proposed method is later tested in numerical experiment on two measured datasets from Luxembourg school and office,equipped with batteries and ground source heat *** system allows the reduction of CO_(2) emission and improvement of self-consumption,size reduction of the photovoltaic array installed at the facilities by at least by half as well as substituting battery storage by thermal storage,reducing the initial investment to the ***,despite 3.6 times difference in efficiency between heat pumps and storage heaters,the system equipped with latter have potential to achieve similar performance in carbon reduction,suggesting that energy storage have more prominent carbon reduction effect,than the power consumption,making cheaper systems with storage heaters a possible alternative to heat pumps.

关键词： Hybrid energy storage Photovoltaic Artificial intelligence Green house gases Energy management

Multiscale wood micromechanics and size effects study via nanoindentation

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生物质资源与工程(英文) 2023年第3期8卷 246-264页

作者： Yuri I.Golovin alexander A.Gusev Dmitry Yu.Golovin Sergey M.Matveev alexander I.Tyrin alexander A.Samodurov Viktor V.Korenkov Inna A.Vasyukova Maria A.Yunack Institute“Nanotechnology and Nanomaterials” G.R.Derzhavin Tambov State University392000 TambovRussia Department of Chemical Enzymology School of ChemistryLomonosov Moscow State University119991 MoscowRussia Research and Educational Center«Sustainable Development of the Forest Complex» Voronezh State Forestry University Named after G.F.Morozov394087 VoronezhRussia Department of Functional Nanosystems and High-Temperature Materials National University of Science and Technology“MISIS”119991 MoscowRussia

Wood as a material is a natural composite with a complex hierarchically arranged *** scale levels of wood structure contribute to its macroscopic mechanical *** nature of such characteristics and deformation modes differs radically at different scale *** macroscopic properties are well studied,and the relevant information can be easily found in the ***,the knowledge of the deformation mechanisms at the mesoscopic level corresponding to the cellular structure of early and late wood layers of annual growth rings is *** hinders building the comprehensive multiscale model of how wood mechanical properties are *** paper described the results of scanning of mechanical properties of softwood and hardwood samples,such as common pine,small-leaf lime,and pedunculate oak,by means of nanoindentation(NI).The NI technique allows varying the size of deformed region within a wide range by altering maximal load(P max)applied to the indenter so that one can re-peatedly and non-destructively test wood structural components at different scale levels on the same sample without changing the technique or *** was discovered that the effective microhardness(H eff)and Young’s modulus(E eff)decreased manifold with P max growing from 0.2 to 2000 *** drop in H effwas observed when the locally deformed region grew,and re-sulting from P max increase generally follows the rule similar to the Hall-Petch relation for yield stress,strength,and hardness initially established for metals and alloys,though obviously in those cases the underlying internal mechanisms are quite *** nature and micromechanisms of such size effect(SE)in wood revealed using NI were discussed in this *** P max<0.2 mN,the deformed area under the pyramidal Berckovich indenter was much smaller than the cell wall ***,in this case,NI measured the internal mechanical properties of the cell wall material as long as free boundaries impact

关键词： Nano/microhardness Scanning nanoindentation Annual growth ring Early and late wood Dendrochronology

Evaluation of the function of a luciferase-like monooxygenase homologue in 4,4´-dithiodibutyric acid catabolism in Rhodococcus erythropolis MI2

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Systems Microbiology and Biomanufacturing 2022年第3期2卷 523-532页

作者： M.Venkateswar Reddy alexander Steinbüchel Institut für Molekulare Mikrobiologie und Biotechnologie Westfälische Wilhelms-Universität Münster48149 MünsterGermany Center for Biotechnology and Interdisciplinary Studies Rensselaer Polytechnic Institute1108th StreetTroyNY 12180USA Environmental Sciences Department King Abdulaziz UniversityJeddahSaudi Arabia

The bacterium Rhodococcus erythropolis MI2 uses 4,4´-dithiodibutyric acid(DTDB)as carbon source to synthesize polythioesters(PTE).The first step for the production of PTE using DTDB is catalyzed by an NADH:flavin oxidoreductase(nox)as it was previously shown in our laboratory,and the second step is catabolized by a putative luciferase-like monooxygenase(Llm).In the current study,experiments were carried out to identify the function of ***,the llm gene,which encodes for the Llm protein,was amplified from the genomic DNA of MI2 using polymerase chain reaction and expressed in Escherichia coli BL21 *** purification was done using His Spin Trap affinity *** assay was carried out using the purified protein and p-coumaric acid as substrate giving a specific activity of 1.6 U/mg protein for the purified *** responsible gene(llm)was deleted in the genome of MI2,and a single deletion mutant was subsequently ***,growth of the wild-type strain(MI2)and the mutant strain(MI2Δllm)were compared using DTDB or succinate as carbon *** the wild type was successfully grown with DTDB or succinate,the llm-negative mutant exhibited low grow with DTDB although it grows very well with succinate.

关键词： Deletion mutant Monooxygenase Polythioesters Protein purification Rhodococcus erythropolis MI2 4,4´-Dithiodibutyric acid(DTDB)