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fAST discovery of an extremely radio-faint millisecond pulsar from the fermi-LAT unassociated source 3fGL J0318.1+0252

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Science China(Physics,Mechanics & Astronomy) 2021年第12期64卷 10-17页

作者： Pei Wang Di Li Colin J.Clark Pablo M.Saz Parkinson Xian Hou Weiwei Zhu Lei Qian Youling Yue Zhichen Pan Zhijie Liu Xuhong Yu Shanping You Xiaoyao Xie Qijun Zhi Hui Zhang Jumei Yao Jun Yan Chengmin Zhang Kwok Lung fan Paul S.Ray Matthew Kerr David A.Smith peter f.michelson Elizabeth C.ferrara David J.Thompson Zhiqiang Shen Na Wang fAST&fermi-LAT Collaboration CAS Key Laboratory of fAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Jodrell Bank Centre for Astrophysics Department of Physics and AstronomyUniversity of ManchesterManchester M139PLUK Department of Physics and Laboratory for Space Research University of Hong KongHong Kong 999077China Santa Cruz Institute for Particle Physics University of CaliforniaSanta Cruz CA 95064USA Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China School of Computer Science and Technology Key Laboratory of Information and Computing Guizhou ProvinceGuizhou Normal UniversityGuiyang 550001China School of Physics and Electronic Science Guizhou Normal UniversityGuiyang 550001China Physics Department Stanford UniversityStanford CA 94305USA UMCP/CRESST/GSfC NASAGreenbeltMaryland MD 20771USA GSfC NASAGreenbeltMaryland MD 20771USA Centre d’´Etudes Nucl´eaires de Bordeaux Gradignan IN2P3/CNRSUniversit´e BordeauxGradignan 33175France Space Science Division U.S.Naval Research LaboratoryWashington DC 20375-5352USA Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China Xinjiang Astronomical Observatory Urumqi 830011China Department of Physics University of MarylandCollege Park MD 20742USA NAOC-UKZN Computational Astrophysics Centre University of KwaZulu-NatalDurban 4000South Africa 不详

High sensitivity radio searches of unassociated γ-ray sources have proven to be an effective way of finding new pulsars. Using the five-hundred-meter Aperture Spherical radio Telescope(fAST) during its commissioning phase, we have carried out a number of targeted deep searches of fermi Large Area Telescope(LAT) γ-ray sources. On february 27, 2018 we discovered an isolated millisecond pulsar(MSP), PSR J0318+0253, coincident with the unassociated γ-ray source 3 fGL J0318.1+0252. PSR J0318+0253 has a spin period of 5.19 ms, a dispersion measure(DM) of 26 pc cm-3 corresponding to a DM distance of about 1.3 kpc, and a period-averaged flux density of(~11±2) μJy at L-band(1.05-1.45 GHz). Among all high energy MSPs, PSR J0318+0253 is the faintest ever detected in radio bands, by a factor of at least ~4 in terms of L-band fluxes. With the aid of the radio ephemeris, an analysis of 9.6 years of fermi-LAT data revealed that PSR J0318+0253 also displays strong γ-ray pulsations. follow-up observations carried out by both Arecibo and fAST suggest a likely spectral turn-over around 350 MHz. This is the first result from the collaboration between fAST and the fermi-LAT teams as well as the first confirmed new MSP discovery by fAST, raising hopes for the detection of many more MSPs. Such discoveries will make a significant contribution to our understanding of the neutron star zoo while potentially contributing to the future detection of gravitational waves, via pulsar timing array(PTA) experiments.

关键词： fAST pulsar radio gamma rays

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A product version of the Hilton-Milner-frankl theorem

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Science China Mathematics 2024年第2期67卷 455-474页

作者： peter frankl Jian Wang Alfréd Rényi Institute of Mathematics Hungarian Academy of SciencesBudapest H-1053Hungary Department of Mathematics Taiyuan University of TechnologyTaiyuan 030024China

Two families f and G of k-subsets of {1, 2,..., n} are called non-trivial cross t-intersecting if|f ∩ G|≥t for all f ∈ f, G ∈ G and | ∩ {f : f ∈ f}| < t, | ∩ {G : G ∈ G}| < t. In the present paper,we determine... 详细信息

Two families f and G of k-subsets of {1, 2,..., n} are called non-trivial cross t-intersecting if|f ∩ G|≥t for all f ∈ f, G ∈ G and | ∩ {f : f ∈ f}| f the sizes of two non-trivial cross t-intersecting families of k-subsets of{1, 2,..., n} for n≥4(t + 2)2k2, k≥5, which is a product version of the Hilton-Milner-frankl theorem.

关键词： extremal set theory cross t-intersecting family product version non-trivial

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地球演化历史中氧逸度变化对壳幔循环启动、风化和超大陆循环的指示

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Science Bulletin 2024年第1期69卷 97-102页

作者：王瑞邬绍宸 Roberto f.Weinberg William J.Collins peter A.Cawood State Key Laboratory of Geological Processes and Mineral Resources Institute of Earth SciencesChina University of GeosciencesBeijing 100083China frontiers Science Center for Deep-time Digital Earth China University of Geosciences(Beijing)Beijing 100083China School of Earth Atmosphere and EnvironmentMonash UniversityClayton VIC 3800Australia The Institute for Geoscience Research Curtin UniversityPerth WA 6102Australia

We apply a zircon redox index to a global compilation of detrital zircons to track the variation of oxidation state,expressed asΔfMQ,through Earth's history.Those from I-type rocks,which comprise mantle and crustal igneous protoliths,including tonalite–trondhjemite–granodiorites(TTGs),generally have a high oxidation state(ΔfMQ>0).In contrast,zircons from igneous rocks derived from supracrustal source rocks(S-type)are commonly reduced(ΔfMQfunction derived from the Gaussian-Kernel-Density-Estimation,we use the maximum likelihood estimation(MLE)to distinguish Stype from I-type zircons through Earth's history using zircon redox.Voluminous S-type magma production shows a ca.600 Ma cyclicity that is closely related to the supercontinent cycle.We link a cyclic drop in redox values after 2.6 Ga to periodic S-type magma generation associated with burial and melting of metasedimentary rocks during supercontinent assembly and amalgamation.TheΔfMQ of the detrital zircons rise at~3.5 Ga followed by a consistent averageΔfMQ>0 over the last 3 Ga.Given that the redox state of magmas is independent of crustal thickness and silica variation,and elevated values are likely more closely related to tectonic setting,we suggest that the consistent averageΔfMQ>0 from ca.3.5 Ga onwards relates to recycling of oceanic lithosphere back into the mantle in what eventually became established as subduction zones.The more reduced magmas associated with sedimentary sources,became established at 2.6 Ga,presumably in response to continental rocks rising above sealevel,and follow peaks of productivity associated with the supercontinent cycle.

关键词： Oxidation state Supercontinent Weathering Subduction Zircon Granite

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A Survey on Sensor-and Communication-Based Issues of Autonomous UAVs

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Computer Modeling in Engineering & Sciences 2024年第2期138卷 1019-1050页

作者： Pavlo Mykytyn Marcin Brzozowski Zoya Dyka peter Langendoerfer IHP-Leibniz-Institut für Innovative Mikroelektronik Wireless SystemsFrankfurt(Oder)15236Germany BTU Cottbus-Senftenberg Faculty 1:MINTCottbus03046German

The application field for Unmanned Aerial Vehicle (UAV) technology and its adoption rate have been increasingsteadily in the past years. Decreasing cost of commercial drones has enabled their use at a scale broader thanever before. However, increasing the complexity of UAVs and decreasing the cost, both contribute to a lack ofimplemented securitymeasures and raise new security and safety concerns. for instance, the issue of implausible ortampered UAV sensor measurements is barely addressed in the current research literature and thus, requires moreattention from the research community. The goal of this survey is to extensively review state-of-the-art literatureregarding common sensor- and communication-based vulnerabilities, existing threats, and active or passive cyberattacksagainst UAVs, as well as shed light on the research gaps in the literature. In this work, we describe theUnmanned Aerial System (UAS) architecture to point out the origination sources for security and safety issues.Weevaluate the coverage and completeness of each related research work in a comprehensive comparison table as wellas classify the threats, vulnerabilities and cyber-attacks into sensor-based and communication-based categories.Additionally, for each individual cyber-attack, we describe existing countermeasures or detectionmechanisms andprovide a list of requirements to ensureUAV’s security and safety.We also address the problem of implausible sensormeasurements and introduce the idea of a plausibility check for sensor data. By doing so, we discover additionalmeasures to improve security and safety and report on a research niche that is not well represented in the currentresearch literature.

关键词： Unmanned aerial vehicle unmanned aerial system cyber security and privacy drone swarm security vulnerabilities cyber-threats cyber-attacks plausibility check

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Identific tion of quantitative trait loci and associated candidate genes for pregnancy success in Angus–Brahman crossbred heifers

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Journal of Animal Science and Biotechnology 2024年第1期15卷 162-170页

作者： Quinn A.Hoorn Gabriel A.Zayas Eduardo E.Rodriguez Laura M.Jensen Raluca G.Mateescu peter J.Hansen Department of Animal Sciences Donald Henry Barron Reproductive and Perinatal Biology Research Programand the Genetics InstituteUniversity of FloridaGainesvilleFLUSA School of Applied Systems Biology La Trobe UniversityBundooraVIC 3083Australia

Background In beef cattle, more than 50% of the energy input to produce a unit of beef is consumed by the female that produced the calf. Development of genomic tools to identify females with high genetic merit for reproductive function could increase the profitability and sustainability of beef production.Results Genome-wide association studies(GWAS) were performed using a single-step genomic best linear unbiased prediction approach on pregnancy outcome traits from a population of Angus–Brahman crossbred heifers. furthermore, a validation GWAS was performed using data from another farm. Heifers were genotyped with the Bovine GGP f250 array that contains 221,077 SNPs. In the discovery population, heifers were bred in winter breeding seasons involving a single round of timed artificial insemination(AI) followed by natural mating for 3 months. Two phenotypes were analyzed: pregnancy outcome to first-service AI(PAI;n = 1,481) and pregnancy status at the end of the breeding season(PEBS;n = 1,725). The heritability was estimated as 0.149 and 0.122 for PAI and PEBS, respectively. In the PAI model, one quantitative trait locus(QTL), located between 52.3 and 52.5 Mb on BTA7, explained about 3% of the genetic variation, in a region containing a cluster of γ-protocadherin genes and SLC25A2. Other QTLs explaining between 0.5% and 1% of the genetic variation were found on BTA12 and 25. In the PEBS model, a large QTL on BTA7 was synonymous with the QTL for PAI, with minor QTLs located on BTA5, 9, 10, 11, 19, and 20. The validation population for pregnancy status at the end of the breeding season were Angus–Brahman crossbred heifers bred by natural mating. In concordance with the discovery population, the large QTL on BTA7 and QTLs on BTA10 and 12 were identified.Conclusions In summary, QTLs and candidate SNPs identified were associated with pregnancy outcomes in beef heifers, including a large QTL associated with a group of protocadherin genes. Confirmation of these associations with larger populations could lead to the develo

关键词： Beef cattle fertility GWAS QTL

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Volcanic Risk Perception and Coping Strategies from Mounts Cameroon and Nyiragongo Eruptions, Central Africa: A Comparative Analysis

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Journal of Geoscience and Environment Protection 2024年第6期12卷 161-189页

作者： Mabel N. Wantim Innocent Bradriyo Asong f. Zisuh Louis M. Balgawa Mero Yannah Katcho Karume Nde-fon peter Bih Amban Nchini L. Wayih Emmanuel V. Yenshu Samuel N. Ayonghe Unit of Disaster Risk Management Department of Environmental Science University of Buea Buea Cameroon Observatoire Volcanologique de Goma (OVG) Goma Democratic Republic of the Congo Institute of Geological and Mining Research (IRGM) Yaounde Cameroon faculty of Health Sciences University of Buea Buea Cameroon faculty of Social and Management Sciences University of Buea Buea Cameroon

Approximately 2,000,000 people are exposed to volcanic risks in communities situated at the flanks of Mounts Cameroon (MC) and Nyiragongo (MN) volcanoes in Central Africa. This study therefore sought to investigate risk perception from four previous eruptions of MC, namely the 1959, 1982, 1999, and 2000 eruptions;and two previous eruptions of MN: 1977 and 2002. The study was initiated with co-design workshops held with major stakeholders in the cities of Buea and Goma at the flanks of MC and MN, respectively, in 2017, to develop the research objectives for the study. A non-random questionnaire survey was later conducted within 14 and 15 communities in Buea and Goma respectively, on the effects, perceived risks, and coping strategies for the chosen eruptions. Three age groups (18 - 30, 31 - 45 and >45 years) and gender (male and female) were considered. The population at the flanks of both volcanoes cited scientific and indigenous factors to be responsible for eruptions from these volcanoes. At MC and MN, ≥45% of the sampled participants (with a higher female population) perceived that the sampled eruptions posed a very high risk to the population. In terms of the effects, the age group of 18 - 30 was the least knowledgeable. In terms of direct effect on persons, over 90% of participants at MC and MN attested that they were overcome by fear/panic. On measures to cope with any likely eruption, the following order was established at the flanks of both volcanoes: sensitization of population, use of religious (prayers) and of traditional/indigenous strategies. In terms of future coping strategies, while the males at MC maintained sensitization as the favourite option, 62% of the males at MN opted for traditional/indigenous strategies. The female population at both MC and MN showed a higher preference for religious strategies like prayers.

关键词： Risk Perception Mount Cameroon Mount Nyiragongo Indigenous Buea Goma

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Characterisation of undigested components throughout the gastrointestinal tract of broiler chickens fed either a wheat-or maizebased diet

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Animal Nutrition 2022年第1期8卷 153-159页

作者： Eunjoo Kim Natalie K.Morgan Amy f.Moss Lily Li peter Ader Mingan Choct School of Environmental and Rural Science University of New EnglandArmidaleNSW2351Australia BASf South East Asia038987Singapore BASf SE 68623LampertheimGermany

This study was to characterise the undigested nutrients present along the gastrointestinal tract of birds offered common wheat-or maize-based diets,with the goal of optimising utilisation of enzymes to enhance digestive efficiency.Wheat-and maize-based diets were offered to 240 mixed-sex broilers(10 birds/pen;n=12)from 1 to 35 d postehatch.Digestibility of dry matter,starch,crude protein and nonstarch polysaccharides(NSP)were measured in the crop,gizzard,duodenum,jejunum,ileum,caeca and excreta at d 12 and 35 postehatch.Analysis of nutrient levels in the excreta presented that more than 30%of nutrients provided in the feed was wasted,irrespective of wheat or maize diet type.On average,92 g/kg crude protein,92 g/kg insoluble NSP and 14 g/kg oligosaccharides were not utilised by birds at d 12 postehatch.The quantity of water-insoluble NSP in the small intestine at d 12 was lower in birds offered the wheat-based diet compared to those fed the maize-based diet(Pfor water-soluble NSP(Pf age.At this time period,accumulation of feed in the gizzard was noted for birds offered both diets,but was more pronounced in those offered the maize-based diet(Pffered the maize-based diet demonstrated improved utilisation of oligosaccharides compared to those fed the wheat-based diet at both d 12 and 35(P=0.087 and P=0.047,respectively).Protein utilisation in the jejunum and ileum was greater in birds offered the wheat-based diet compared to those fed the maize-based diet(P=0.004 and Pformance of birds,the degree and flow of nutrient disappearance along the gastrointestinal tract was influenced by cereal type and bird age.

关键词： Broiler chicken Nutrient digestibility Undigested dietary component

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Non-starch polysaccharide-degrading enzymes may improve performance when included in wheat- but not maize-based diets fed to broiler chickens under subclinical necrotic enteritis challenge

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Animal Nutrition 2022年第3期10卷 54-67页

作者： Eunjoo Kim Amy f.Moss Natalie K.Morgan Kosar Gharib-Naseri peter Ader Mingan Choct School of Environmental and Rural Science University of New EnglandArmidaleNSW 2351Australia BASf SE 68623LampertheimGermany

The present study investigated whether supplementing fibre-degrading enzymes can ameliorate the severity of subclinical necrotic enteritis(NE)in broiler chickens offered wheat-or maize-based diets.A total of 1,544 mixed-sex broiler chickens were assigned to 16 experimental treatments as a 2×2×4 factorial arrangement of treatments.The factors were the following:NE challenge,yes or no;diet type,wheat-or maize-based;and enzyme supplementation,control(no enzyme),family 10 xylanase(XYN10),family 11 xylanase(XYN11)or b-mannanase(MAN).Each treatment was replicated 6 times,with 16 birds per replicate pen.A three-way challenge×diet type×enzyme interaction occurred for body weight at 21 d of age(P=0.025)and overall feed conversion ratio(P=0.001).In the non-challenged birds fed the wheat-based diet,supplementing MAN increased d 21 body weight compared to the control.In challenged birds fed the maize-based diet,supplemental XYN11 impeded body weight and overall fCR compared to the control.Birds offered the maize-based diet presented heavier relative gizzard weights at both 16 and 21 d of age(Pfed the wheatbased diet.Enzyme supplementation reduced ileal and jejunal digesta viscosity at 16 d of age only in birds fed the wheat-based diet(Pfed the maizebased diet,and MAN reduced it in birds fed the wheat-based diet at 21 d of age(P=0.030).Supplementing XYN11 improved ileal soluble non-starch polysaccharides(NSP)digestibility in birds fed the wheat-based diet compared to non-supplemented birds(Pfed the wheat-based diet displayed a higher abundance of Bifidobacterium,Lactobacillus and Enterobacteriaceae and butyric acid in the caeca at 16 d of age compared to birds fed the maize-based diet(Pf NE on growth performance in birds fed the maizebased diet.Supplementing wheat-based diets with fibre-degrading enzymes ameliorates production l

关键词： Broiler chicken Carbohydrase Mannanase Necrotic enteritis Prebiotic oligosaccharides Xylanase

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Ileal profile of non-starch polysaccharides and oligosaccharides in response to exogenous enzymes in broiler chickens offered wheat-or maize-based diets under subclinical necrotic enteritis challenge

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Animal Nutrition 2022年第3期10卷 207-215页

The present study evaluated the impacts of fibre-degrading enzymes on the profiles of non-starch polysaccharides(NSP)and oligosaccharides(OS)in the ileum of broiler chickens offered wheat-or maize-based diets under subclinical necrotic enteritis(NE)challenge.A 224 factorial arrangement of treatments was used.factors were the following:NE challenge,no or yes;diet type,wheat-or maizebased;and supplemental enzymes,control(no enzyme),family 10 xylanase(XYN10),family 11 xylanase(XYN11)or b-mannanase(MAN).Birds in the challenged group were inoculated with Eimeria on d 9 and Clostridium perfringens on d 14 and 15.A 3-way interaction(P=0.047)occurred on overall(d 0 to 16)weight gain.When NE was present,all the supplemental enzymes increased weight gain in birds fed the wheat-based diet;whereas in those fed the maize-based diet supplemental XYN10 and XYN11 decreased weight gain.When NE was absent,birds fed the wheat-based diet supplemented with XYN10 or MAN presented increased weight gain compared to non-supplemented birds,but no improvements with enzyme addition were observed in birds fed the maize-based diet.A 3-way interaction(P=0.002)was observed on insoluble NSP level in the ileum.When NE was absent,all the supplemental enzymes reduced the ileal level of insoluble NSP,regardless of diet type.In the challenged birds,supplementing XYN10 and MAN reduced insoluble NSP level in the ileum,but only in birds fed the wheat-based diet.Ileal soluble NSP level was reduced by supplemental XYN11 and MAN,but only in birds fed the wheatbased diet,resulting in a 2-way diet typeenzyme interaction(Pffered the wheat-based diet supplemented with XYN11.Collectively,supplementation of NSP-degrading enzymes to the wheat-based diet enhanced bird performance regardless of NE challenge,with XYN11 significantly increasing oligosaccharide release.However,enzyme addition did not improve growth performance in birds fed maize-based diet,with supplemental XYN10 and XYN11 impeding weig

关键词： Broiler chicken Non-starch polysaccharide Subclinical necrotic enteritis Oligosaccharide

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Phase field modeling with large driving forces

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npj Computational Materials 2023年第1期9卷 623-631页

作者： Jin Zhang Alexander f.Chadwick David L.Chopp peter W.Voorhees Department of Materials Science and Engineering Northwestern UniversityEvanstonIL 60208USA Department of Engineering Sciences and Applied Mathematics Northwestern UniversityEvanstonIL 60208USA

There is growing interest in applying phase field methods as quantitative tools in materials discovery and development.However,large driving forces,common in many materials systems,lead to unstable phase field profiles,thus requiring fine spatial and temporal resolution.This demands more computational resources,limits the ability to simulate systems with a suitable size,and deteriorates the capability of quantitative prediction.Here,we develop a strategy to map the driving force to a constant perpendicular to the interface.Together with the third-order interpolation function,we find a stable phase field profile that is independent of the magnitude of the driving force.The power of this approach is illustrated using three models.We demonstrate that by using the driving force extension method,it is possible to employ a grid size orders of magnitude larger than traditional methods.This approach is general and should apply to many other phase field models.

关键词： forces interpolation apply

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