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Michael R. Hoffmann

Bio: Michael R. Hoffmann is an academic researcher from California Institute of Technology. The author has contributed to research in topics: IUCN Red List & Biodiversity. The author has an hindex of 109, co-authored 500 publications receiving 63474 citations. Previous affiliations of Michael R. Hoffmann include Clarkson University & International Union for Conservation of Nature and Natural Resources.


Papers
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Journal ArticleDOI
TL;DR: The slow pace of hazardous waste remediation at military installations around the world is causing a serious delay in conversion of many of these facilities to civilian uses as discussed by the authors, which is a serious problem.
Abstract: The civilian, commercial, and defense sectors of most advanced industrialized nations are faced with a tremendous set of environmental problems related to the remediation of hazardous wastes, contaminated groundwaters, and the control of toxic air contaminants. For example, the slow pace of hazardous waste remediation at military installations around the world is causing a serious delay in conversion of many of these facilities to civilian uses. Over the last 10 years problems related to hazardous waste remediation have emerged as a high national and international priority.

17,188 citations

Journal ArticleDOI
TL;DR: In this article, the presence of metal ion dopants in the TiO_2 crystalline matrix significantly influences photoreactivity, charge carrier recombination rates, and interfacial electron-transfer rates.
Abstract: A systematic study of metal ion doping in quantum (Q)-sized (2-4 nm) TiO_2 colloids is performed by measuring their photoreactivities and the transient charge carrier recombination dynamics. The presence of metal ion dopants in the TiO_2 crystalline matrix significantly influences photoreactivity, charge carrier recombination rates, and interfacial electron-transfer rates. The photoreactivities of 21 metal ion-doped colloids are quantified in terms of both the conduction band electron reduction of an electron acceptor (CCl_4 dechlorination) and the valence band hole oxidation of an electron donor (CHCl_3 degradation). Doping with Fe^(3+), Mo^(5+), Ru^(3+), Os^(3+), Re^(5+), V^(4+), and Rh^(3+) at 0.1-0.5 at.% significantly increases the photoreactivity for both oxidation and reduction while Co^(3+) and Al^(3+) doping decreases the photoreactivity. The transient absorption signals upon laser flash photolysis (λ_(ex) = 355 nm) at λ = 600 nm are extended up to 50 ms for Fe^(3+)-, V^(4+)-, Mo^(5+)-, and Ru^(3+)-doped TiO_2 while the undoped Q-sized TiO_2 shows a complete "blue electron" signal decay within 200 μs. Co^(3+)- and Al^(3+)-doped TiO_2 are characterized by rapid signal decays with a complete loss of absorption signals within 5 μs. The quantum yields obtained during CW photolyses are quantitatively correlated with the measured transient absorption signals of the charge carriers. Photoreactivities are shown to increase with the relative concentration of trapped charge carriers. The photoreactivity of doped TiO_2 appears to be a complex function of the dopant concentration, the energy level of dopants within the TiO_2 lattice, their d electronic configuration, the distribution of dopants, the electron donor concentration, and the light intensity.

3,508 citations

Journal ArticleDOI
07 Jul 2006-Science
TL;DR: It is hoped this synthesis improves understanding of these prioritization approaches and that it results in more efficient allocation of geographically flexible conservation funding.
Abstract: The location of and threats to biodiversity are distributed unevenly, so prioritization is essential to minimize biodiversity loss. To address this need, biodiversity conservation organizations have proposed nine templates of global priorities over the past decade. Here, we review the concepts, methods, results, impacts, and challenges of these prioritizations of conservation practice within the theoretical irreplaceability/vulnerability framework of systematic conservation planning. Most of the templates prioritize highly irreplaceable regions; some are reactive (prioritizing high vulnerability), and others are proactive (prioritizing low vulnerability). We hope this synthesis improves understanding of these prioritization approaches and that it results in more efficient allocation of geographically flexible conservation funding.

1,951 citations

Journal ArticleDOI
Jan Schipper1, Jan Schipper2, Janice Chanson2, Janice Chanson1, Federica Chiozza3, Neil A. Cox1, Neil A. Cox2, Michael R. Hoffmann2, Michael R. Hoffmann1, Vineet Katariya2, John F. Lamoreux4, John F. Lamoreux2, Ana S. L. Rodrigues5, Ana S. L. Rodrigues6, Simon N. Stuart1, Simon N. Stuart2, Helen J. Temple2, Jonathan E. M. Baillie7, Luigi Boitani3, Thomas E. Lacher4, Thomas E. Lacher1, Russell A. Mittermeier, Andrew T. Smith8, Daniel Absolon, John M. Aguiar1, John M. Aguiar4, Giovanni Amori, Noura Bakkour1, Noura Bakkour9, Ricardo Baldi10, Ricardo Baldi11, Richard J. Berridge, Jon Bielby7, Jon Bielby12, Patricia Ann Black13, Julian Blanc, Thomas M. Brooks14, Thomas M. Brooks15, Thomas M. Brooks1, James Burton16, James Burton17, Thomas M. Butynski18, Gianluca Catullo, Roselle Chapman, Zoe Cokeliss7, Ben Collen7, Jim Conroy, Justin Cooke, Gustavo A. B. da Fonseca19, Gustavo A. B. da Fonseca20, Andrew E. Derocher21, Holly T. Dublin, J. W. Duckworth10, Louise H. Emmons22, Richard H. Emslie2, Marco Festa-Bianchet23, Matthew N. Foster, Sabrina Foster24, David L. Garshelis25, C. Cormack Gates26, Mariano Gimenez-Dixon, Susana González, José F. González-Maya, Tatjana C. Good27, Geoffrey Hammerson28, Philip S. Hammond29, D. C. D. Happold30, Meredith Happold30, John Hare, Richard B. Harris31, Clare E. Hawkins32, Clare E. Hawkins14, Mandy Haywood33, Lawrence R. Heaney34, Simon Hedges10, Kristofer M. Helgen22, Craig Hilton-Taylor2, Syed Ainul Hussain35, Nobuo Ishii36, Thomas Jefferson37, Richard K. B. Jenkins38, Charlotte H. Johnston8, Mark Keith39, Jonathan Kingdon40, David Knox1, Kit M. Kovacs41, Kit M. Kovacs42, Penny F. Langhammer8, Kristin Leus43, Rebecca L. Lewison44, Gabriela Lichtenstein, Lloyd F. Lowry45, Zoe Macavoy12, Georgina M. Mace12, David Mallon46, Monica Masi, Meghan W. McKnight, Rodrigo A. Medellín47, Patricia Medici48, G. Mills, Patricia D. Moehlman, Sanjay Molur, Arturo Mora2, Kristin Nowell, John F. Oates49, Wanda Olech, William R.L. Oliver, Monik Oprea22, Bruce D. Patterson34, William F. Perrin37, Beth Polidoro2, Caroline M. Pollock2, Abigail Powel50, Yelizaveta Protas9, Paul A. Racey38, Jim Ragle2, Pavithra Ramani24, Galen B. Rathbun51, Randall R. Reeves, Stephen B. Reilly37, John E. Reynolds52, Carlo Rondinini3, Ruth Grace Rosell-Ambal1, Monica Rulli, Anthony B. Rylands, Simona Savini, Cody J. Schank24, Wes Sechrest24, Caryn Self-Sullivan, Alan Shoemaker2, Claudio Sillero-Zubiri40, Naamal De Silva, David E. Smith24, Chelmala Srinivasulu53, P. J. Stephenson, Nico van Strien54, Bibhab Kumar Talukdar55, Barbara L. Taylor37, Rob Timmins, Diego G. Tirira, Marcelo F. Tognelli11, Marcelo F. Tognelli56, Katerina Tsytsulina, Liza M. Veiga57, Jean-Christophe Vié2, Elizabeth A. Williamson58, Sarah A. Wyatt, Yan Xie, Bruce E. Young28 
Conservation International1, International Union for Conservation of Nature and Natural Resources2, Sapienza University of Rome3, Texas A&M University4, University of Cambridge5, Instituto Superior Técnico6, Zoological Society of London7, Arizona State University8, Columbia University9, Wildlife Conservation Society10, National Scientific and Technical Research Council11, Imperial College London12, National University of Tucumán13, University of Tasmania14, University of the Philippines Los Baños15, Earthwatch Institute16, University of Edinburgh17, Drexel University18, Global Environment Facility19, Universidade Federal de Minas Gerais20, University of Alberta21, Smithsonian Institution22, Université de Sherbrooke23, University of Virginia24, Minnesota Department of Natural Resources25, University of Calgary26, James Cook University27, NatureServe28, University of St Andrews29, Australian National University30, University of Montana31, General Post Office32, University of Otago33, Field Museum of Natural History34, Wildlife Institute of India35, Tokyo Woman's Christian University36, National Oceanic and Atmospheric Administration37, University of Aberdeen38, University of the Witwatersrand39, University of Oxford40, Norwegian Polar Institute41, University Centre in Svalbard42, Copenhagen Zoo43, San Diego State University44, University of Alaska Fairbanks45, Manchester Metropolitan University46, National Autonomous University of Mexico47, University of Kent48, City University of New York49, Victoria University of Wellington50, California Academy of Sciences51, Mote Marine Laboratory52, Osmania University53, White Oak Conservation54, Aaranyak55, University of California, Davis56, Museu Paraense Emílio Goeldi57, University of Stirling58
10 Oct 2008-Science
TL;DR: In this paper, the authors present a comprehensive assessment of the conservation status and distribution of the world's mammals, including marine mammals, using data collected by 1700+ experts, covering all 5487 species.
Abstract: Knowledge of mammalian diversity is still surprisingly disparate, both regionally and taxonomically. Here, we present a comprehensive assessment of the conservation status and distribution of the world's mammals. Data, compiled by 1700+ experts, cover all 5487 species, including marine mammals. Global macroecological patterns are very different for land and marine species but suggest common mechanisms driving diversity and endemism across systems. Compared with land species, threat levels are higher among marine mammals, driven by different processes (accidental mortality and pollution, rather than habitat loss), and are spatially distinct (peaking in northern oceans, rather than in Southeast Asia). Marine mammals are also disproportionately poorly known. These data are made freely available to support further scientific developments and conservation action.

1,383 citations

Journal ArticleDOI
08 Apr 2004-Nature
TL;DR: It is shown that the global network of protected areas is far from complete, and the inadequacy of uniform—that is, ‘one size fits all’—conservation targets is demonstrated, in the first global gap analysis assessing the effectiveness ofprotected areas in representing species diversity.
Abstract: The Fifth World Parks Congress in Durban, South Africa, announced in September 2003 that the global network of protected areas now covers 11.5% of the planet's land surface. This surpasses the 10% target proposed a decade earlier, at the Caracas Congress, for 9 out of 14 major terrestrial biomes. Such uniform targets based on percentage of area have become deeply embedded into national and international conservation planning. Although politically expedient, the scientific basis and conservation value of these targets have been questioned. In practice, however, little is known of how to set appropriate targets, or of the extent to which the current global protected area network fulfils its goal of protecting biodiversity. Here, we combine five global data sets on the distribution of species and protected areas to provide the first global gap analysis assessing the effectiveness of protected areas in representing species diversity. We show that the global network is far from complete, and demonstrate the inadequacy of uniform--that is, 'one size fits all'--conservation targets.

1,344 citations


Cited by
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28 Jul 2005
TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1(PfPMP1)与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员,通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

18,940 citations

Journal ArticleDOI
Ryoji Asahi1, Takeshi Morikawa1, T. Ohwaki1, Koyu Aoki1, Y. Taga1 
13 Jul 2001-Science
TL;DR: Film and powders of TiO2-x Nx have revealed an improvement over titanium dioxide (TiO2) under visible light in optical absorption and photocatalytic activity such as photodegradations of methylene blue and gaseous acetaldehyde and hydrophilicity of the film surface.
Abstract: To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Films and powders of TiO 2- x N x have revealed an improvement over titanium dioxide (TiO 2 ) under visible light (wavelength 2 has proven to be indispensable for band-gap narrowing and photocatalytic activity, as assessed by first-principles calculations and x-ray photoemission spectroscopy.

11,402 citations

Journal ArticleDOI
15 Nov 2013-Science
TL;DR: Intensive forestry practiced within subtropical forests resulted in the highest rates of forest change globally, and boreal forest loss due largely to fire and forestry was second to that in the tropics in absolute and proportional terms.
Abstract: Quantification of global forest change has been lacking despite the recognized importance of forest ecosystem services. In this study, Earth observation satellite data were used to map global forest loss (2.3 million square kilometers) and gain (0.8 million square kilometers) from 2000 to 2012 at a spatial resolution of 30 meters. The tropics were the only climate domain to exhibit a trend, with forest loss increasing by 2101 square kilometers per year. Brazil's well-documented reduction in deforestation was offset by increasing forest loss in Indonesia, Malaysia, Paraguay, Bolivia, Zambia, Angola, and elsewhere. Intensive forestry practiced within subtropical forests resulted in the highest rates of forest change globally. Boreal forest loss due largely to fire and forestry was second to that in the tropics in absolute and proportional terms. These results depict a globally consistent and locally relevant record of forest change.

7,890 citations

ReportDOI
TL;DR: PHREEQC as discussed by the authors is a C program written in the C programming language that is designed to perform a wide variety of low-temperature aqueous geochemical calculations.
Abstract: PHREEQC version 2 is a computer program written in the C programming language that is designed to perform a wide variety of low-temperature aqueous geochemical calculations. PHREEQC is based on an ion-association aqueous model and has capabilities for (1) speciation and saturation-index calculations; (2) batch-reaction and onedimensional (1D) transport calculations involving reversible reactions, which include aqueous, mineral, gas, solidsolution, surface-complexation, and ion-exchange equilibria, and irreversible reactions, which include specified mole transfers of reactants, kinetically controlled reactions, mixing of solutions, and temperature changes; and (3) inverse modeling, which finds sets of mineral and gas mole transfers that account for differences in composition between waters, within specified compositional uncertainty limits. New features in PHREEQC version 2 relative to version 1 include capabilities to simulate dispersion (or diffusion) and stagnant zones in 1D-transport calculations, to model kinetic reactions with user-defined rate expressions, to model the formation or dissolution of ideal, multicomponent or nonideal, binary solid solutions, to model fixed-volume gas phases in addition to fixed-pressure gas phases, to allow the number of surface or exchange sites to vary with the dissolution or precipitation of minerals or kinetic reactants, to include isotope mole balances in inverse modeling calculations, to automatically use multiple sets of convergence parameters, to print user-defined quantities to the primary output file and (or) to a file suitable for importation into a spreadsheet, and to define solution compositions in a format more compatible with spreadsheet programs. This report presents the equations that are the basis for chemical equilibrium, kinetic, transport, and inverse modeling calculations in PHREEQC; describes the input for the program; and presents examples that demonstrate most of the program's capabilities.

7,654 citations