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A relational database of global U-Pb ages

Geoscience Frontiers 2018年第3期9卷 877-891页

作者： stephen J.Puetz Progressive Science Institute HonoluluHI 96815USA

Enhanced understanding of how sampling techniques affect estimates of the global U-Pb age-distribution have, in turn, constrained U-Pb database design. Recent studies indicate that each continent has a unique age-distribution, as determined by zircon ages dated by the U-Pb isotope method. Likewise, broad regions within a continent also exhibit diverse age-distributions. To achieve a reliable estimate of the global distribution, the heterogenous composition of the continental crust requires sampling as many regions as feasibly possible. To attain this goal, and to provide a method for calculating age histograms, the records from a recent global U-Pb compilation are supplemented with 281,631 new records. These additions increase the database size to 700,598 records. In addition, the data are now restructured and made available as a relational database. After filtering the records by the six age-models included with the database, the results reveal two problems that might generally be unrecognized. First, an abrupt switch in the best-age at any given point(such as 1000 Ma) from ^(206)Pb/^(238)U ages to ^(207)Pb/^(206)Pb ages artificially depresses the age-distribution at the cutoff point. Second, rejecting analyses based on either absolute discordance or the magnitude of 2σ precision errors artificially depresses the age-distribution between 900 Ma and 2000 Ma. The results indicate that, when estimating the global U-Pb age-distribution, the methods for determining best-age and for rejecting records both require some attention. Possible solutions include using either an Accuracy Model or a Precision Model for estimating best-age, and then including all U-Pb records in the estimate, rather than rejecting any of them.

关键词： U-Pb age-distribution Histogram Global database Sampling Filtering Zircon

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Breather Dynamics of the Sine-Gordon Equation

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Communications in Theoretical Physics 2013年第6期59卷 664-670页

作者： stephen Johnson Anjan Biswas stephen Johnson and Anjan Biswas Department of Mathematical Sciences Delaware State University Department of Mathematics Faculty of Science King Abdulaziz University

This paper studies the adiabatic dynamics of the breather soliton of the sine-Gordon equation. The integrals of motion are found and then used in soliton perturbation theory to derive the differential equation governing the soliton velocity. Time-dependent functions arise and their properties are studied. These functions are found to be bounded and periodic and affect the soliton velocity. The soliton velocity is numerically plotted against time for different combinations of initial velocities and perturbation terms.

关键词： solitons phonons conservation laws perturbations numerics

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Suspension Splittings and Self-maps of Flag Manifolds

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Acta Mathematica Sinica,English Series 2019年第4期35卷 445-462页

作者： Shizuo KAJI stephen THERIAULT Institute of Mathematics for Industry Kyushu University Mathematical Sciences University of Southampton

If G is a compact connected Lie group and T is a maximal torus, we give a wedge decomposition of ΣG/T by identifying families of idempotents in cohomology. This is used to give new information on the self-maps of G/T.

关键词： Flag manifold self-map stable splitting

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An integrated measurement and modeling methodology for estuarine water quality management

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Water Science and Engineering 2015年第1期8卷 9-19页

作者： Michael Hartnett stephen Nash Department of Civil Engineering National University of Ireland

This paper describes research undertaken by the authors to develop an integrated measurement and modeling methodology for water quality management of estuaries. The approach developed utilizes modeling and measurement results in a synergistic manner. Modeling results were initially used to inform the field campaign of appropriate sampling locations and times, and field data were used to develop accurate models. Remote sensing techniques were used to capture data for both model development and model validation. Field surveys were undertaken to provide model initial conditions through data assimilation and determine nutrient fluxes into the model domain. From field data, salinity re- lationships were developed with various water quality parameters, and relationships between chlorophyll a concentrations, transparency, and light attenuation were also developed. These relationships proved to be invaluable in model development, particularly in modeling the growth and decay of chlorophyll a. Cork Harbour, an estuary that regularly experiences summer algal blooms due to anthropogenic sources of nutrients, was used as a case study to develop the methodology. The integration of remote sensing, conventional fieldwork, and modeling is one of the novel aspects of this research and the approach developed has widespread applicability.

关键词： Estuarine modeling Hydrodynamics Water quality management Nutrients Phytoplankton Field measurements Remote sensing

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Beef and cone-in-cone calcite fibrous cements associated with the end-Permian and end-Triassic mass extinctions： Reassessment of processes of formation

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Journal of Palaeogeography 2016年第1期5卷 28-42页

作者： stephen Kershaw Li Guo Department of Life Sciences Brunel Uniuersity Kingston Lane Uxbridge Middlesex UB8 3PH UK CASP University of Cambridge 181a Huntingdon Road CB3 0DH Cambridge UK

This paper reassesses published interpretation that beef and cone-in-cone （B-CIC） fibrous calcite cements were precipitated contemporaneously just below the sea floor in uncon- solidated sediment, in limestones associated with the end-Permian （P/T） and end-Triassic （T/J） mass extinctions. That interpretation introduced the concept of a sub-seafloor car- bonate factory associated with ocean acidification by raised carbon dioxide driven by volcanic eruption, coinciding with mass extinction. However, our new fieldwork and petrographic analysis, with literature comparison, reveals several problems with this concept. Two key points based on evidence in the T/J transition of the UK are：（I） that B-CIC calcite deposits form thin scattered layers and lenses at several horizons, not a distinct deposit associated with volcanic activity; and （2） B-CIC calcite is more common in Early Jurassic sediments after the extinction and after the end of the Central Atlantic Magmatic Province volcanism proposed to have supplied the carbon dioxide required. Our samples from Late Triassic, Early Jurassic and Early Cretaceous limestones in southern UK show that B-CIC calcite occurs in both marine and non-marine sediments, therefore ocean processes are not mandatory for its formation. There is no proof that fibrous calcite was formed before lithification, but our Early Jurassic samples do prove fibrous calcite formed after compaction, thus interpretation of crystal growth in uncon- solidated sediment is problematic. Furthermore, B-CIC crystals mostly grew both upwards and downwards equally, contradicting the interpretation of the novel carbonate factory that they grew preferentially upwards in soft sediment. Finally, Early Jurassic and Early Cretaceous examples are not associated with mass extinction. Three further key points derived from the literature include：（I） B-CIC calcite is wide- spread geographically and stratigraphically, not clustered around mass extinctions or the Paleocene-E

关键词： End-Permian mass extinction End-Triassic mass extinctionBeefCone-in-cone calciteOcean acidification

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Captcha-Based Honey Net Model against Malicious Codes

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Journal of Computer and Communications 2023年第3期11卷 159-166页

作者： adeniyi Akanni Williams Akanni Oluwafunmilasyo Helen Daso Department of Computer Science Caleb University Lagos Lagos Nigeria Akademia Humanistyczno-Ekonomiczna w &Lstrok odzi &Lstrokód&zacute Poland National Population Commission Headquarters Abuja Nigeria

The rate of passive and active attacks has been on the increase lately affecting both individuals and institutions. Even when internal control procedures are in place, malicious codes from intruders into the network have left so much to be desired. As a result, many Chief Information Security Officers have grown grey hair because of their inability to effectively handle attacks from various ends. Various attempts and technologies have been made in the time past with a measure of success. Intrusion Detection Software (IDS), Intrusion Prevention Software, firewall, honey pots and honey nets have been deployed and with great respite from losses arising from cyber-attacks. Cyber security is the duty of everyone and all must see it as such. As tiers of government and law enforcement agents are doing their best, everybody must be seen to play their parts. Fraudsters have also not seemed to be tired of seeking vulnerabilities to exploit. Then, cyber security experts should not let off their guards but make efforts to harden their security. A way of doing is to intelligently provide a solution that has the capability of detecting and proactively hardening security. This paper proposes a honey net model that is captcha-based and capable of extracting details from hackers with a view to building a robust defense against black hat attackers. This research was able to prevent the botnet with the use of captcha and also redirect suspected traffic to the honeynet which was then captured for the purpose of improving the security of the network. The result showed that any bandwidth greater than the set threshold was not allowed to go into the network but redirected to honeynet where details were logged. Also, with a threshold of 100 mbs, inbound traffic of higher bandwidth such as 110 mbs and 150 mbs was denied access thereby giving 100% detection rate.

关键词： Passive Attack Active Attack Honey Net Malware Internet of Things (IoT) Log

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High-resolution flood modeling of urban areas using MSN_Flood

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Water Science and Engineering 2017年第3期10卷 175-183页

作者： Michael Hartnett stephen Nash Department of Civil Engineering National University of IrelandGalwayIreland

Although existing hydraulic models have been used to simulate and predict urban flooding, most of these models are inadequate due to the high spatial resolution required to simulate flows in urban floodplains. Nesting high-resolution subdomains within coarser-resolution models is an efficient solution for enabling simultaneous calculation of flooding due to tides, surges, and high river flows. MSN_Flood has been developed to incorporate moving boundaries around nested domains, permitting alternate flooding and drying along the boundary and in the interior of the domain. Ghost cells adjacent to open boundary cells convert open boundaries, in effect, into internal boundaries. The moving boundary may be multi-segmented and non-continuous, with recirculating flow across the boundary. When combined with a bespoke adaptive interpolation scheme, this approach facilitates a dynamic internal boundary. Based on an alternating-direction semi-implicit finite difference scheme,MSN_Flood was used to hindcast a major flood event in Cork City resulting from the combined pressures of fluvial, tidal, and storm surge processes. The results show that the model is computationally efficient, as the 2-m high-resolution nest is used only in the urban flooded ***, lower-resolution nests are used. The results also show that the model is highly accurate when compared with measured data. The model is capable of incorporating nested sub-domains when the nested boundary is multi-segmented and highly complex with lateral gradients of elevation and velocities. This is a major benefit when modelling urban floodplains at very high resolution.

关键词： Multi-scale nesting Surge-fluvial flooding Urban flooding Multi-segmented boundary Moving boundary

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Glycemic index and glycemic load of selected Chinese traditional foods

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World Journal of Gastroenterology 2010年第12期16卷 1512-1517页

作者： stephen Heung-sang Wong Department of Sports Science and Physical Education The Chinese University of Hong Kong

AIM:To determine the glycemic index(GI)and glycemic load(GL)values of Chinese traditional foods in Hong ***:Fifteen healthy subjects(8 males and 7 females)volunteered to consume either glucose or one of 23 test foods after 10-14 h overnight *** blood glucose concentrations were analyzed immediately before,15,30,45,60,90 and 120 min after food consumption using capillary blood *** GI value of each test food was calculated by expressing the incremental area under the blood glucose response curve(IAUC)value for the test food as a percentage of each subject's average IAUC value for the *** GL value of each test food was calculated as the GI value of the food multiplied by the amount of the available carbohydrate in a usual portion size,divided by ***:Among all the 23 Chinese traditional foods tested,6 of them belonged to low GI foods(Tuna Fish Bun,Egg Tart,Green Bean Dessert,Chinese Herbal Jelly,Fried Rice Vermicelli in Singapore-style,and Spring Roll),10 of them belonged to moderate GI foods(Baked Barbecued Pork Puff,Fried Fritter,"Mai-Lai"Cake,"Pineapple"Bun,Fried Rice Noodles with Sliced Beef,Barbecue Pork Bun,Moon Cakes,Glutinous Rice Ball,Instant Sweet Milky Bun,and Salted Meat Rice Dumpling),the others belonged to high GI foods(Fried Rice in Yangzhou-Style,Sticky Rice Wrapped in Lotus Leaf,Steamed Glutinous Rice Roll,Jam and Peanut Butter Toast,Plain Steamed Vermicelli Roll,Red Bean Dessert,and Frozen Sweet Milky Bun).CONCLUSION:The GI and GL values for these Chinese traditional foods will provide some valuable information to both researchers and public on their food preference.

关键词： Glycemic index Glycemic load Chinese traditional foods

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Impact of surface hydroxylation in MgO-/SnO-nanocluster modified TiO_2 anatase(101) composites on visible light absorption, charge separation and reducibility

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Chinese Chemical Letters 2018年第6期29卷 757-764页

作者： stephen Rhatigan Michael Nolan Tyndall National Institute University College Cork

Surface modification with metal oxide nanoclusters has emerged as a candidate for the enhancement of the photocatalytic activity of titanium dioxide. An increase in visible light absorption and the suppression of charge carrier recombination are necessary to improve the efficiency. We have studied Mg4O4 and Sn4O4 nanoclusters modifying the（101） surface of anatase TiO2 using density functional theory corrected for on-site Coulomb interactions（DFT ＋ U）. Such studies typically focus on the pristine surface, free of the point defects and surface hydroxyls present in real surfaces. We have also examined the impact of partial hydroxylation of the anatase surface on a variety of outcomes such as nanocluster adsorption, light absorption, charge separation and reducibility. Our results indicate that the modifiers adsorb strongly at the surface, irrespective of the presence of hydroxyl groups, and that modification extends light absorption into the visible range while enhancing UV activity. Our model for the excited state of the heterostructures demonstrates that photoexcited electrons and holes are separated onto the TiO2 surface and metal oxide nanocluster respectively. Comparisons with bare TiO2 and other TiO2-based photocatalyst materials are presented throughout.

关键词： Photocatalyst Titania Visible-light absorption Surface modification Charge separation Surface hydroxylation Oxygen vacancy formation

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Thermochemical recycling of waste disposable facemasks in a non-electrically powered system

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Low-carbon Materials and Green Construction 2023年第1期1卷 146-156页

作者： Kingsley O.Iwuozor Ebuka Chizitere Emenike Agbana Abiodun stephen Otoikhian Shegun Kevin Joy Adeleke Adewale George adeniyi Department of Pure and Industrial Chemistry Nnamdi Azikiwe UniversityP.M.B.5025AwkaNigeria Department of Chemical Engineering University of IlorinP.M.B.1515IlorinNigeria Edo State University UzairueNigeria Chemical Engineering Department Landmark UniversityOmu-AranNigeria

The COVID-19 pandemic encouraged the use of plastic-based personal protective equipment (PPE), which aidedgreatly in its management. However, the increased production and usage of these PPEs put a strain on the environment,especially in developing and underdeveloped countries. This has led various researchers to study low-costand effective technologies for the recycling of these materials. One such material is disposable facemasks. However,previous studies have only been able to engage electrically powered reactors for their thermochemical conversion,which is a challenge as these reactors cannot be used in regions with an insufficient supply of electricity. In thisstudy, the authors utilized a biomass-powered reactor for the conversion of waste disposable facemasks and almondleaves into hybrid biochar. The reactor, which is relatively cheap, simple to use, environmentally friendly, and modifiedfor biochar production, is biomass-powered. The co-carbonization process, which lasted 100 min, produced a 46%biochar yield, which is higher than previously obtained biochar yields by other researchers. The biochar thus obtainedwas characterized to determine its properties. FTIR analysis showed that the biochar contained functional groupssuch as alkenes, alkynes, hydroxyls, amines, and carbonyls. The EDX analysis revealed that the biochar was primarilymade of carbon, tellurium, oxygen, and calcium in the ratios of 57%, 19%, 9%, and 7%, respectively. The inclusion ofthe facemask decreased the surface area and porosity of the biochar material, as evidenced by its surface area andpore characteristics.

关键词： Biochar Biomass Covid-19 Facemask Thermochemical conversion

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