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Successional trends and processes on a glacial foreland in Southern Iceland studied by repeated species counts

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Ecological Processes 2019年第1期8卷 138-148页

作者： Taylor g.glausen lawrence H.Tanner Jacobs School of Medicine and Biomedical Sciences State University of New York at BuffaloBuffaloNY 14203USA Department of Biological and Environmental Sciences Le Moyne CollegeSyracuseNY 13214USA

Introduction:Primary succession on glacial forelands is increasingly relevant as rapid glacial retreat is exposing growing land areas to plant *** investigated temporal trends,controls,and outcomes in floral succession on a subarctic glacial ***,we examined changes in community composition(mosses,low shrubs,forbs,trees,and graminoids)over long-term(decadal)and short-term(nd attempted to identify the underlying processes responsible for the observed successional ***:The study area was the foreland of the Skaftafellsjӧkull,located in Vatnajӧkull national Park near the south coast of *** established nine transect lines at varying distances from the ice front representing surfaces of age ranging from less than one decade to over 100 *** transect consisted of five measurement stations of 1 m2 where we measured vegetative cover(VC),species richness(SR),and species density(SD)and calculated species evenness(SE).Measurements were made initially in 2007 and repeated at the same geographic coordinates in ***:VC increased with distance from the ice front from 16%to over 90%.SR and SD increased from the youngest pioneer community through a mid-successional stage corresponding to an age of over 60 but less than 100 *** VC but declining SR,SD,and SE characterized the oldest(over 100 years)bryophyte-dominated *** turnover,which involved forbs almost exclusively,increased moderately from early through midsuccessional sites and declined on older *** of the measurements made in 2014 to those made in 2007 demonstrates increased SR at mid-successional sites while SD remained relatively ***:At a small scale,colonization is controlled by local factors such as microtopography and aspect,particularly in proximity to the *** the landscape level,changes in VC and community structure are controlled by time and nutrient *** nutrient level

关键词： Primary succession glacial foreland Species richness Species density Bryophyte

Paleosols of the upper Paleozoic Sangre de Cristo Formation,north-central new Mexico:Record of early Permian palaeoclimate in tropical Pangaea

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Journal of Palaeogeography 2017年第2期6卷 144-161页

作者： lawrence H. Tanner Spencer g. Lucas Department of Biological Sciences Le Moyne CollegeSyracuseNY 13214USA new Mexico Museum of natural History 1801 Mountain Road N.W.AlbuquerqueNM 87014USA

The lower Permian(Wolfcampian) Sangre de Cristo Formation of northern new Mexico consists of silty mudstones and laterally discontinuous sandstones deposited on an aggrading alluvial ***,mudstones display a variety of pedogenic *** mudstone fabrics vary from platy to prismatic;some beds display prominent pedogenic ***-colored root traces are common throughout the section,as are calcareous nodules,which vary from small bodies with diffuse boundaries to vertically stacked,discrete,cm-scale nodules(rhizocretions),and less commonly form coalescing *** occur only in the lower portion of the ca.90-m measured *** of the mudstone beds contain calcretes that are immature(calcic Protosols to calcic Argillisols),but the lower to middle portion of the section also contains mature calcrete horizons(argillic Calcisols and Calcisols).Intercalated micritic limestone beds with sharp contacts containing root traces,are of laterally variable thickness and grade to nodular *** are interpreted as floodplain pond carbonates that have undergone pedogenic alteration(palustrine limestones),indicating long periods of exposure under strongly seasonal climatic *** isotopic composition of the pedogenic carbonate displays a substantial range of values,but most of the range of variation in isotopic composition is accounted for by isotopically heavier carbonate(both carbon and oxygen) precipitated in shallow ponds subject to intense pedogenic reworking(palustrine carbonate).During the early Permian,northern new Mexico was situated in a near equatorial position(ca.4° n).The overall character of the paleosols suggests a persistent warm,semi-humid,seasonal climate throughout most of the interval of deposition during the Wolfcampian,but with episodically increased aridity during formation of the more mature *** long-term trend of climate change is evident in the stratigraphic section examined for this study.

关键词： Sangre de Cristo Formation Wolfcampian Vertisol Argillisol Calcisol Protosol

End-Triassic nonmarine biotic events

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Journal of Palaeogeography 2015年第4期4卷 331-348页

作者： Spencer g.Lucas lawrence H.Tanner new Mexico Museum of natural History Department of Biological Sciences Le Moyne College

The Late Triassic was a prolonged interval of elevated extinction rates and low origination rates that manifested themselves in a series of extinctions during Carnian, norian and Rhaetian time. Most of these extinctions took place in the marine realm, particularly affecting radiolarians, conodonts, bivalves, ammonoids and reef-building organisms. On land, the case for a Late Triassic mass extinction is much more tenuous and has largely focused on tetrapod vertebrates（amphibians and reptiles）, though some workers advocate a sudden endTriassic（TJB） extinction of land plants. nevertheless, an extensive literature does not identify a major extinction of land plants at the TJB, and a comprehensive review of palynological records concluded that TJB vegetation changes were non-uniform（different changes in different places）, not synchronous and not indicative of a mass extinction of land plants. Claims of a substantial perturbation of plant ecology and diversity at the TJB in East greenland are indicative of a local change in the paleoflora largely driven by lithofacies changes resulting in changing taphonomic filters. Plant extinctions at the TJB were palaeogeographically localized events, not global in extent. With new and more detailed stratigraphic data, the perceived TJB tetrapod extinction is mostly an artifact of coarse temporal resolution, the compiled correlation effect. The amphibian, archosaur and synapsid extinctions of the Late Triassic are not concentrated at the TJB, but instead occur stepwise, beginning in the norian and extending into the Hettangian. There was a disruption of the terrestrial ecosystem across the TJB, but it was more modest than generally claimed. The ecological severity of the end-Triassic nonmarine biotic events are relatively low on the global scale. Biotic turnover at the end of the Triassic was likely driven by the CAMP（Central Atlantic Magmatic Province） eruptions, which caused significant environmental perturbations（cooling, warming,

关键词： Triassic-Jurassic boundary mass extinction land plants East greenland tetrapods newark Supergroup CAMP volcanism

Estimating risk factors of urban malaria in Blantyre, Malawi: A spatial regression analysis

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Asian Pacific Journal of Tropical Biomedicine 2016年第5期6卷 376-381页

作者： lawrence n.Kazembe Don P.Mathanga Statistics Department University of Namibia Malaria Alert Centre College of MedicineUniversity of Malawi Department of Community Health College of MedicineUniversity of Malawi

Objective: To estimate risk factors of urban malaria in Blantyre, Malawi, with the goal of understanding the epidemiology and ecology of the disease, and informing malaria elimination policies for African urban cities that have markedly low prevalence of ***: We used a case-control study design, with cases being children under the age of five years diagnosed with malaria, and matched controls obtained at hospital and communities. The data were obtained from ndirande health facility catchment area. We then fitted a multivariate spatial logistic model of malaria risk. Covariate and risk factors in the model included child-specific, household and environmental risk factor(nearness to garden, standing water, river and swamps). The spatial component was assumed to follow a gaussian process and model fitted using Bayesian ***: Our findings showed that children who visited rural areas were 6 times more likely to have malaria than those who did not [odds ratio(OR) = 6.66, 95% confidence interval(CI): 4.79–9.61]. The risk of malaria increased with age of the child(OR = 1.01,95% CI: 1.003–1.020), but reduced with high socio-economic status compared to lower status(OR = 0.39, 95% CI: 0.25–0.54 for the highest level and OR = 0.67, 95% CI: 0.47–0.94 for the medium level). Although nearness to a garden, river and standing water showed increased risk, these effects were not significant. Furthermore, significant spatial clusters of risk emerged, which does suggest other factors do explain malaria risk variability apart from those established ***: As malaria in urban areas is highly fuelled by rural-urban migration,emphasis should be to optimize information, education and communication prevention strategies, particularly targeting children from lower socio-economic position.

关键词： Urban malaria Travel history Spatial regression geo-additive models Blantyre Malawi

Delayed peripheral treatment with neurotrophin-3 improves sensorimotor recovery after central nervous system injury

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neural Regeneration Research 2019年第10期14卷 1703-1704页

作者： Sotiris g.Kakanos lawrence D.F.Moon neurorestoration group Wolfson Centre for Age-Related DiseasesKing’s College of London

neurotrophin-3 (nT3) is a growth factor found in many body tissues including the heart, intestines, skin, nervous system and in skeletal muscles including muscle spindles (Murase et al., 1994). nT3 is required for the survival, correct connectivity and function of sensory (“proprioceptive”) afferents that innervate muscle spindles;these neurons express receptors for nT3 including tropomyocin receptor kinase C. These proprioceptive afferents are important for normal movement (Boyce and Mendell, 2014) and signals from muscle spindles are important for recovery of limb movement (e.g., after spinal cord lateral hemisection)(Takeoka et al., 2014). The level of nT3 declines in most tissues during postnatal development;its level is low in adult and elderly humans and other mammals (Murase et al., 1994). Elevation of nT3 has been shown to improve outcome in various animal models of neurological disease and injury. For example, many groups have shown that delivery of nT3 directly into the central nervous system promotes recovery after spinal cord injury but this often involved invasive routes or gene therapy (Boyce and Mendell, 2014;Petrosyan et al., 2015;Wang et al., 2018).

关键词： neurotrophin-3(nT3) tissues including the heart Boyce and Mendell

Seek and Ye Shall [eventually] Find： The End of the Search for the Auxin Receptor

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Journal of Integrative Plant Biology 2005年第12期47卷 1412-1417页

作者： lawrence HOBBIE Department of Biology Adelphi University Garden City New York 11530 USA

The mechanism by which the plant hormone auxin regulates gene expression has been shown to involve regulated degradation, through the ubiquitin-proteasome pathway, of transcriptional repressor proteins. However, the key first component in this pathway, the receptor that binds auxin and initiates auxin signaling, has remained a mystery. Two recent papers identify the F-box protein TIR1, part of the complex that attaches ubiquitin to its targets, as an auxin receptor. This breakthrough reveals a new mode of signal transduction and lays the groundwork for a more complete understanding of auxin physiology.

关键词： auxin auxin receptor SCF complex signal transduction ubiquitin.

Strategies for creating living, additively manufactured, open-cellular metal and alloy implants by promoting osseointegration,osteoinduction and vascularization: An overview

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Journal of Materials Science & Technology 2019年第2期35卷 231-241页

作者： lawrence E.Murr Department of Metallurgical Materials and Biomedical Engineering The University of Texas at El Paso W.M.Keck Center for 3D Innovation The University of Texas at El Paso

Additive manufacturing of porous, open-cellular metal or alloy implants, fabricated by laser or electron beam melting of a powder bed, is briefly reviewed in relation to optimizing biomechanical compatibility by assuring elastic(Young's) modulus matching of proximate bone, along with corresponding pore sizes assuring osseointegration and vasculature development and migration. In addition, associated, requisite compressive and fatigue strengths for such implants are described. Strategies for optimizing osteoblast(bone cell) development and osteoinduction as well as vascularization of tissue in 3 D scaffolds and tissue engineering constructs for bone repair are reviewed in relation to the biology of osteogenesis and neovascularization in bone, and the role of associated growth factors, bone morphogenic proteins, signaling molecules and the like. Prospects for infusing hydrogel/collagen matrices containing these cellular and protein components or surgically extracted intramedullary(bone marrow) concentrate/aspirate containing these biological and cell components into porous implants are discussed, as strategies for creating living implants, which over the long term would act as metal or alloy scaffolds.

关键词： Additive manufacturing Open cellular metal and alloy implants Electron beam melting Living implant strategies Vascularization Osseointegration Osteoinduction

Frontiers of 3D Printing/Additive Manufacturing: from Human Organs to Aircraft Fabrication

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Journal of Materials Science & Technology 2016年第10期32卷 987-995页

作者： lawrence E.Murr Department of Metallurgical Materials and Biomedical Engineering The University of Texas at El Paso W.M.Keck Center for 3D Innovation The University of Texas at El Paso

It has been more than three decades since stereolithography began to emerge in various forms of additive manufacturing and 3D printing. Today these technologies are proliferating worldwide in various forms of advanced manufacturing. The largest segment of the 3D printing market today involves various polymer component fabrications, particularly complex structures not attainable by other manufacturing *** printer head systems have also been adapted to selectively print various speciated human cells and special molecules in attempts to construct human organs, beginning with skin and various tissue patches. These efforts are discussed along with metal and alloy fabrication of a variety of implant and bone replacement components by creating powder layers, which are selectively melted into complex forms（such as foams and other open-cellular structures） using laser and electron beams directed by CAD software. Efforts to create a ＂living implant＂ by bone ingrowth and eventual vascularization within these implants will be discussed briefly. novel printer heads for direct metal droplet deposition as in other 3D printing systems are briefly described since these concepts will allow for the eventual fabrication of very large and complex products, including automotive and aerospace structures and components.

关键词： 3D printing/additive manufacturing Laser and electron beam melting Organ printing Organ and implant vascularization Metal droplet printing

Linear Bayes Estimators Applied to the Inverse gaussian Lifetime Model

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Journal of Systems Science & Complexity 2016年第6期29卷 1683-1692页

作者： WAng Lichun PETTIT lawrence Department of Mathematics Beijing Jiaotong University School of Mathematical Sciences Queen Mary University of London

For the two-parameter inverse gaussian distribution denoted by Ig（μ,A）, the authors employ a linear Bayes procedure to estimate the parameters μ and A. The superiority of the proposed linear Bayes estimator （LBE） over both the classical UMVUE and the maximum likelihood estimator （MLE） is established in terms of the mean squared error matrix （MSEM） criterion. Compared with the usual Bayes estimator, which is obtained by an MCMC method, the proposed LBE is simple and easy to use. Some numerical results are presented to verify that the LBE performs well.

关键词： Linear Bayes method MCMC method mean squared error matrix (MSEM) quadraticloss.