National Library of Energy BETA

Sample records for koch karlt ijp

  1. Argonne nuclear pioneer: Leonard Koch

    SciTech Connect (OSTI)

    Koch, Leonard

    2012-01-01

    Leonard Koch joined Argonne National Laboratory in 1948. He helped design and build Experimental Breeder Reactor-1 (EBR-1), the first reactor to generate useable amounts of electricity from nuclear energy.

  2. Core Analysis At Jemez Mountain Area (Eichelberger & Koch, 1979...

    Open Energy Info (EERE)

    Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Core Analysis At Jemez Mountain Area (Eichelberger & Koch, 1979) Exploration Activity...

  3. Rock Sampling At Jemez Mountain Area (Eichelberger & Koch, 1979...

    Open Energy Info (EERE)

    Rock Sampling At Jemez Mountain Area (Eichelberger & Koch, 1979) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Rock Sampling At Jemez Mountain...

  4. Microsoft PowerPoint - Roadrunner-Salishan-Koch-20070426.ppt

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Roadrunner 1 Operated by the Los Alamos National Security, LLC for the DOE/NNSA Ken Koch & Andy White Roadrunner Project Los Alamos National Laboratory Salishan Conference on High-Speed Computing April 26, 2007 Roadrunner and hybrid computing LA-UR-07-2919 Salishan Roadrunner 2 Operated by the Los Alamos National Security, LLC for the DOE/NNSA Outline 1. Cell & Hybrid 2. Roadrunner Architecture (original & improved) 3. Programming & Applications Operated by the Los Alamos

  5. BPA-2014-00175-FOIA Consult Request

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of Koch Industries: Hobson Bernardino & Davis (on Behalf of Koch Industries) Hunton& Williams (on Behalf of Koch Industries Latham & Watkins (on Behalf of Koch Industries I llusch...

  6. Paula T. Hammond | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Paula T. Hammond About Us Paula T. Hammond - David H. Koch Professor in Engineering and Head of the Department of Chemical Engineering, MIT Paula T. Hammond Paula T. Hammond is the Head of the Department of Chemical Engineering and David H. Koch Chair Professor in Engineering at the Massachusetts Institute of Technology (MIT). She is a member of MIT's Koch Institute for Integrative Cancer Research, the MIT Energy Initiative, and a founding member of the MIT Institute for Soldier Nanotechnology.

  7. Performance of an LPD prototype detector at MHz frame rates under...

    Office of Scientific and Technical Information (OSTI)

    at MHz frame rates under Synchrotron and FEL radiation Authors: Koch, Andreas ; Hart, Matthew ; Nicholls, Tim ; Angelsen, Christian ; Coughlan, John ; French, Marcus ;...

  8. Strategies of Gammarus pulex L. to cope with arsenic - Results...

    Office of Scientific and Technical Information (OSTI)

    Authors: Schaller, Jrg 1 ; Koch, Iris 2 ; Caumette, Guilhem 2 ; Nearing, Michelle 2 ; Reimer, Kenneth J. 2 ; Planer-Friedrich, Britta 1 + Show Author Affiliations ...

  9. Attendees

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Dorothy Koch DOE BER BER Program Manager Yukiko Sekine DOE ASCR NERSC Program Manager Harvey Wasserman NERSC NERSC User Services (Co-coordinator) Kathy Yelick NERSC Berkeley...

  10. Sudip Dosanjh

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of the International Conference on Numerical Analysis and Applied Mathematics, Rhodes, Greece, September 18, 2010, J. Ang, D. Doerfler, S. Dosanjh, K. Koch, J. Morrison, M. Vigil,...

  11. Search for: All records | Data Explorer

    Office of Scientific and Technical Information (OSTI)

    Huang, Katherine H. (1) Keller, Keith (1) Koche, Richard P. (1) Price, Morgan N. (1) Save Results Excel (limit 2000) CSV (limit 5000) XML (limit 5000) Have feedback or suggestions ...

  12. Aids Epidemic

    ScienceCinema (OSTI)

    None

    2011-04-25

    Exposé avec dias du développement de cette dangereuse épidémie qui est le sida. Le Dr. M.Koch a fait ses études à Hambourg et Kiel.

  13. PowerPoint Presentation

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... distribu on substa on bus market signal me MW me MW TCL power consump on me MW Mathieu, Koch and Callaway, IEEE TPWRS 2012 Market Variability: Trends Prices vary widely over time. ...

  14. I!' L;I)

    Office of Legacy Management (LM)

    ".>;jy i.~jp.~[~~ i,Zz>-c C,+;) ir,i:%J :' 0 p 'd-i I /) f) ic.c iq -.I ,'c i - * w. 3'2 , phi ': r-t;, ; *.i .; I!' L;I) --, -II s;.,yE;J-~,~;~* I' ;, f: >,p.yg ,p ' .L (3 i!>;' !i.3 y/y!-; x>:-y rJgbf;..qp: \' :sF*:l,' 5-".13, -9 _ ..-;~c~-' ~;Li;-~~~~;, 3h' ;[;i-y ; c; ' 1' 1.b y&k' 2 1 , . ..l =i. 1; G.1 ;Tr.; .j. i-:. I qr:i.gky, M,C. Jp, 2.1 F... ii, Ross CENTRAL F ILES ~"CTIVE OF TXIP m --w- The 0' 0 jet% ive Of this trip xas to evaluate tkie !- .zalth

  15. OP-AL-0002-001.PDF

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Doc. ID: OP-AL-0002-001.doc Caretaker Date: 2000/08/03 This authorized list is effective 08/03/2000 and specifies those individuals who have been authorized for Caretaker Operation 1. Aigeldinger, Georg 2. Bucher, Stephanie 3. Choi, Jaewu 4. Koch, Kevin 5. Lian, Kun 6. Ling, Zhong Geng 7. Manohara, Harish 8. Morikawa, Eizi 9. Palshin, Vadim 10. Rupp, Louis 11. Schoonmaker, Mike 12. Scott, John 13. Sprunger, Phil 14. Tittsworth, Roland 15. Xu, Jie Authorization: ________________ ________

  16. Microsoft Word - Li_FinalReport_FASTER.doc

    Office of Scientific and Technical Information (OSTI)

    ATTN: ASR Program Managers, Drs. Dorothy Koch Climate and Environmental Sciences Division Office of Biological and Environmental Research Department of Energy 19901 Germantown Road Germantown, MD20874 Title of Research Project: Continuous Evaluation of Fast Processes in Climate Models Using ARM Measurements Investigator: Zhijin Li, Researcher Joint Institute for Regional Earth System Science and Engineering, UCLA 9258 Boelter Hall, Los Angeles, CA 90095 Phone: (310) 794-5273; Fax: (310)943-1656

  17. Mukul Tikekar > Graduate Student - Archer Group > Researchers, Postdocs &

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Graduates > The Energy Materials Center at Cornell Mukul Tikekar Graduate Student - Archer Group mdt78@cornell.edu Mukul hails from Mumbai, India. He finished his undergraduate education in a Dual Degree - Bachelor of Technology and Master of Technology program in Mechanical Engineering at Indian Institute of Technology, Bombay. Currently a PhD student with the Mechanical and Aerospace Engineering Department, he is jointly advised by Prof Donald Koch and Prof Lynden Archer on modeling of

  18. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Koch, Iris" Name Name ORCID Search Authors Type: All Book/Monograph Conference/Event Journal Article Miscellaneous Patent Program Document Software Manual Technical Report Thesis/Dissertation Subject: Identifier Numbers: Site: All Alaska Power Administration, Juneau, Alaska (United States) Albany Research Center (ARC), Albany, OR (United States) Albuquerque Complex - NNSA Albuquerque Operations Office, Albuquerque, NM (United States) Amarillo National Resource Center for Plutonium,

  19. PowerPoint Presentation

    Energy Savers [EERE]

    Tolerance of Nanostructured Ceramic/Metal Composites Michael Nastasi Director, Nebraska Center for Energy Sciences Research Elmer Koch Professor, Mechanical and Materials Engineering University of Nebraska-Lincoln Work supported by DoE Office of Nuclear Energy, Nuclear Energy Enabling Technologies, award DE-NE0000533 DOE-NE Materials Crosscut Coordination Meeting September 16th, 2015 Co-Investigators: Lin Shao, TAMU and Michael Demkowicz, MIT Vacancies Interstitials Atomic defects produced by

  20. Strategies of Gammarus pulex L. to cope with arsenic - Results from

    Office of Scientific and Technical Information (OSTI)

    speciation analyses by IC-ICP-MS and XAS micro-mapping (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Strategies of Gammarus pulex L. to cope with arsenic - Results from speciation analyses by IC-ICP-MS and XAS micro-mapping Citation Details In-Document Search Title: Strategies of Gammarus pulex L. to cope with arsenic - Results from speciation analyses by IC-ICP-MS and XAS micro-mapping Authors: Schaller, Jörg [1] ; Koch, Iris [2] ; Caumette, Guilhem

  1. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Switch to Detail View for this search SciTech Connect Search Results Page 1 of 1 Search for: All records Creators/Authors contains: "Transistors, Norbert Koch a Dieter Neher TITLE=Moderate Doping Leads to High Performance of Semiconductor /Insulator Polymer Blend" × Sort by Relevance Sort by Date (newest first) Sort by Date (oldest first) Sort by Relevance « Prev Next » Everything1 Electronic Full Text0 Citations1 Multimedia0 Datasets0 Software0 Filter Results Filter by Subject chem

  2. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Switch to Detail View for this search SciTech Connect Search Results Page 1 of 1 Search for: All records Creators/Authors contains: "Schaller, Jörg" × Sort by Relevance Sort by Date (newest first) Sort by Date (oldest first) Sort by Relevance « Prev Next » Everything1 Electronic Full Text0 Citations1 Multimedia0 Datasets0 Software0 Filter Results Filter by Subject Filter by Author Caumette, Guilhem (1) Koch, Iris (1) Nearing, Michelle (1) Planer-Friedrich, Britta (1) Reimer,

  3. Microsoft Word - AL-PO-0001-0007.doc

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Authorized List Doc. ID: OP-AL-0001-007.doc Off-Hours Shift Operator Date: 2001/11/20 This policy is effective 11/20/2001 and denotes those individuals who have been authorized for Off-Hours Shift Operation. 1. Alderman, Steven 2. Aigeldinger, Georg 3. Baethke, Niko 4. Bauer, Benjamin 5. Brendebach, Boris 6. Day, Lorraine 7. Desta, Yohannes 8. Doomes, Edward 9. Dust, Reinhard 10. Farquar, George 11. Fluegge, Michael 12. Goettert, Jost 13. Koch, Kevin 14. Kong, Jong Ren 15. Lian, Kun 16. Ling,

  4. Stochastic Parameterization for Light Absorption by Internally Mixed BC/dust in Snow Grains for Application to Climate Models

    SciTech Connect (OSTI)

    Liou, K. N.; Takano, Y.; He, Cenlin; Yang, P.; Leung, Lai-Yung R.; Gu, Y.; Lee, W- L.

    2014-06-27

    A stochastic approach to model the positions of BC/dust internally mixed with two snow-grain types has been developed, including hexagonal plate/column (convex) and Koch snowflake (concave). Subsequently, light absorption and scattering analysis can be followed by means of an improved geometric-optics approach coupled with Monte Carlo photon tracing to determine their single-scattering properties. For a given shape (plate, Koch snowflake, spheroid, or sphere), internal mixing absorbs more light than external mixing. The snow-grain shape effect on absorption is relatively small, but its effect on the asymmetry factor is substantial. Due to a greater probability of intercepting photons, multiple inclusions of BC/dust exhibit a larger absorption than an equal-volume single inclusion. The spectral absorption (0.2 5 um) for snow grains internally mixed with BC/dust is confined to wavelengths shorter than about 1.4 um, beyond which ice absorption predominates. Based on the single-scattering properties determined from stochastic and light absorption parameterizations and using the adding/doubling method for spectral radiative transfer, we find that internal mixing reduces snow albedo more than external mixing and that the snow-grain shape plays a critical role in snow albedo calculations through the asymmetry factor. Also, snow albedo reduces more in the case of multiple inclusion of BC/dust compared to that of an equal-volume single sphere. For application to land/snow models, we propose a two-layer spectral snow parameterization containing contaminated fresh snow on top of old snow for investigating and understanding the climatic impact of multiple BC/dust internal mixing associated with snow grain metamorphism, particularly over mountains/snow topography.

  5. CP-1 70th Anniversary Symposium

    ScienceCinema (OSTI)

    Len Koch; Harold Agnew

    2013-06-05

    Dr. Harold Agnew, retired director of Los Alamos National Laboratory and one of 49 people present on December 2, 1942 when the world?s first man-made controlled nuclear chain reaction was achieved with the CP-1 reactor, and Dr. Len Koch, one of Argonne?s earliest staff members and a designer of EBR-I, the first liquid metal-cooled fast reactor, spoke about their early work during ?The Dawn of the Nuclear Age?, a Director?s Special Symposium held as one of the events to commemorate the 70th anniversary year of CP-1 achieving criticality. The symposium was moderated by Dr. Charles Till, a retired Argonne associate laboratory director who led Argonne?s nuclear engineering programs throughout the 1980?s and ?90?s. Dr. Agnew painted a vivid picture of the challenges and rewards of working in Enrico Fermi?s group under strict security conditions and the complete faith all in the group had in Fermi?s analyses. He stated that no one ever doubted that CP-1 would achieve criticality, and when the moment came, those present acknowledged the accomplishment with little more than a subdued toast of chianti from a bottle provided by reactor physicist Eugene Wigner. This experimental work on nuclear reactors was continued in the Chicago area and led first by Fermi and then Walter Zinn, another member of Fermi?s CP-1 group, resulting in the formal establishment of Argonne National Laboratory on July 1, 1946. Dr. Koch described how much he enjoyed working at Argonne through the 1950?s and ?60?s and contributing to many of the research ?firsts? that Argonne achieved in the nuclear energy field and led to the foundation of the commercial nuclear power generation industry. His reminiscences about all that was achieved with EBR-I and how that work then led into Argonne?s design, building, and operation of EBR-II as a full demonstration of a fast reactor power plant brought Argonne?s nuclear energy legacy to life for everyone in the auditorium. These engaging presentations prompted a number of questions from the audience, which showed its appreciation for both speakers by ending the symposium with a standing ovation.

  6. Integro-differential modeling of ICRH wave propagation and damping at arbitrary cyclotron harmonics and wavelengths in tokamaks

    SciTech Connect (OSTI)

    Van Eester, D.; Lerche, E.

    2014-02-12

    Both at low and higher cyclotron harmonics, properly accounting for finite Larmor radius effects is crucial in many ion cyclotron resonance frequency heating scenarios creating high energy tails. The present paper discusses ongoing work to extend the 1D TOMCAT wave equation solver [D. Van Eester and R. Koch, Plasma Phys. Contr. Fusion 40 (1998) 1949] to arbitrary harmonics and arbitrary wavelengths. Rather than adopting the particle position, the guiding center position is used as the independent variable when writing down an expression for the dielectric response. Adopting a philosophy originally due to Kaufman [A.N. Kaufman, Phys. Fluids 15 (1972) 1063], the relevant dielectric response in the Galerkin formalism is written in a form where the electric field and the test function vector appear symmetrically, which yields a power balance equation that guarantees non-negative absorption for any wave type for Maxwellian plasmas. Moreover, this choice of independent variable yields intuitive expressions that can directly be linked to the corresponding expressions in the RF diffusion operator. It also guarantees that a positive definite power transfer from waves to particles is ensured for any of the wave modes in a plasma in which all populations have a Maxwellian distribution, as is expected from first principles. Rather than relying on a truncated Taylor series expansion of the dielectric response, an integro-differential approach that retains all finite Larmor radius effects [D. Van Eester and E. Lerche, Plasma Phys. Control. Fusion 55 (2013) 055008] is proposed.

  7. Black Carbon Radiative Forcing over the Tibetan Plateau

    SciTech Connect (OSTI)

    He, Cenlin; Li, Qinbin; Liou, K. N.; Takano, Y.; Gu, Yu; Qi, L.; Mao, Yuhao; Leung, Lai-Yung R.

    2014-11-28

    We estimate the snow albedo forcing and direct radiative forcing (DRF) of black carbon (BC) in the Tibetan Plateau using a global chemical transport model in conjunction with a stochastic snow model and a radiative transfer model. Our best estimate of the annual BC snow albedo forcing in the Plateau is 2.9 W m-2 (uncertainty: 1.55.0 W m-226 ). We find that BC-snow internal mixing increases the albedo forcing by 40-60% compared with external mixing and coated BC increases the forcing by 30-50% compared with uncoated BC, whereas Koch snowflakes reduce the forcing by 20-40% relative to spherical snow grains. Our best estimate of the annual BC DRF at the top of the atmosphere is 2.3 W m-2 (uncertainty: 0.74.3 W m-230 ) in the Plateau after scaling the modeled BC absorption optical depth to Aerosol Robotic Network (AERONET) observations. The BC forcings are attributed to emissions from different regions.

  8. Interobserver Variability in Target Definition for Hepatocellular Carcinoma With and Without Portal Vein Thrombus: Radiation Therapy Oncology Group Consensus Guidelines

    SciTech Connect (OSTI)

    Hong, Theodore S.; Bosch, Walter R.; Krishnan, Sunil; Kim, Tae K.; Mamon, Harvey J.; Ben-Josef, Edgar; Seong, Jinsil; Haddock, Michael G.; Cheng, Jason C.; Feng, Mary U.; Stephans, Kevin L.; Roberge, David; and others

    2014-07-15

    Purpose: Defining hepatocellular carcinoma (HCC) gross tumor volume (GTV) requires multimodal imaging, acquired in different perfusion phases. The purposes of this study were to evaluate the variability in contouring and to establish guidelines and educational recommendations for reproducible HCC contouring for treatment planning. Methods and Materials: Anonymous, multiphasic planning computed tomography scans obtained from 3 patients with HCC were identified and distributed to a panel of 11 gastrointestinal radiation oncologists. Panelists were asked the number of HCC cases they treated in the past year. Case 1 had no vascular involvement, case 2 had extensive portal vein involvement, and case 3 had minor branched portal vein involvement. Theagreement between the contoured total GTVs (primary+vascular GTV) was assessed using the generalized kappa statistic. Agreement interpretation was evaluated using Landis and Koch's interpretation of strength of agreement. The S95 contour, defined using the simultaneous truth and performance level estimation (STAPLE) algorithm consensus at the 95% confidence level, was created for each case. Results: Of the 11 panelists, 3 had treated >25 cases in the past year, 2 had treated 10to 25 cases, 2 had treated 5 to 10 cases, 2 had treated 1 to 5 cases, 1 had treated 0 cases, and 1 did not respond. Near perfect agreement was seen for case 1, and substantial agreement was seen for cases 2 and 3. For case 2, there was significant heterogeneity in the volume identified as tumor thrombus (range 0.58-40.45cc). For case 3, 2 panelists did not include the branched portal vein thrombus, and 7 panelists contoured thrombus separately from the primary tumor, also showing significant heterogeneity in volume of tumor thrombus (range 4.52-34.27cc). Conclusions: In a group of experts, excellent agreement was seen in contouring total GTV. Heterogeneity exists in the definition of portal vein thrombus that may impact treatment planning, especially if differential dosing is contemplated. Guidelines for HCC GTV contouring are recommended.

  9. Comprehensive Sampling of Fourmile Branch and Its Seeplines in the F and H Area of SRS: June 1996 and March 1997

    SciTech Connect (OSTI)

    Koch, J.

    1998-10-30

    In June 1996, and March 1997 water samples were collected from Fourmile Branch (FMB) and its seeplines in the vicinity of the F- and H-Area Seepage basins. These sampling events represent a continuation of a series of semi-annual sampling events, which are now conducted annually and are aimed at characterizing the shallow groundwater outcropping into FMB and its wetlands. In the past, this groundwater has been shown to contain contaminants migrating from the F- and H-Area Seepage basins. The samples were analyzed for metals listed in Title 40, Code of Federal Regulations (CFR), Part 264, Appendix IX, various radionuclides, and selected inorganic constituents and parameters. Volatile organic compounds were not analyzed for in this sampling event since in previous events they were below detection limits, (ref. Dixon 1993, Dixon and Koch 1995).Results from both sampling events indicate that the seeplines of F and H Areas and FMB continue to be influenced by contaminants in groundwater originating from the capped seepage basins, but to a lesser degree than in the past. This suggests that the most concentrated portion of the contaminant plume may have flushed from the system.Contaminant concentrations measured during these two sampling events were compared to background samples collected during these two events and compared to primary drinking water standard (PDWS), secondary drinking water standards (SDWS), and maximum contaminant levels (MCL) enforceable in 1997. Results were also compared to the 1989 baseline measurements at corresponding locations.Using two separate statistical tests, the concentrations of analytes were compared to background samples. The purpose of the tests was to determine if concentrations of contaminants along the F- and H-Area seeplines were greater than background concentrations.

  10. CONVERSION EXTRACTION DESULFURIZATION (CED) PHASE III

    SciTech Connect (OSTI)

    James Boltz

    2005-03-01

    This project was undertaken to refine the Conversion Extraction Desulfurization (CED) technology to efficiently and economically remove sulfur from diesel fuel to levels below 15-ppm. CED is considered a generic term covering all desulfurization processes that involve oxidation and extraction. The CED process first extracts a fraction of the sulfur from the diesel, then selectively oxidizes the remaining sulfur compounds, and finally extracts these oxidized materials. The Department of Energy (DOE) awarded Petro Star Inc. a contract to fund Phase III of the CED process development. Phase III consisted of testing a continuous-flow process, optimization of the process steps, design of a pilot plant, and completion of a market study for licensing the process. Petro Star and the Degussa Corporation in coordination with Koch Modular Process Systems (KMPS) tested six key process steps in a 7.6-centimeter (cm) (3.0-inch) inside diameter (ID) column at gas oil feed rates of 7.8 to 93.3 liters per hour (l/h) (2.1 to 24.6 gallons per hour). The team verified the technical feasibility with respect to hydraulics for each unit operation tested and successfully demonstrated pre-extraction and solvent recovery distillation. Test operations conducted at KMPS demonstrated that the oxidation reaction converted a maximum of 97% of the thiophenes. The CED Process Development Team demonstrated that CED technology is capable of reducing the sulfur content of light atmospheric gas oil from 5,000-ppm to less than 15-ppm within the laboratory scale. In continuous flow trials, the CED process consistently produced fuel with approximately 20-ppm of sulfur. The process economics study calculated an estimated process cost of $5.70 per product barrel. The Kline Company performed a marketing study to evaluate the possibility of licensing the CED technology. Kline concluded that only 13 refineries harbored opportunity for the CED process. The Kline study and the research team's discussions with prospective refineries led to the conclusion that there were not likely prospects for the licensing of the CED process.

  11. Bacterial diversity analysis of Huanglongbing pathogen-infected citrus, using PhyloChip and 16S rRNA gene clone library sequencing

    SciTech Connect (OSTI)

    Shankar Sagaram, U.; DeAngelis, K.M.; Trivedi, P.; Andersen, G.L.; Lu, S.-E.; Wang, N.

    2009-03-01

    The bacterial diversity associated with citrus leaf midribs was characterized 1 from citrus groves that contained the Huanglongbing (HLB) pathogen, which has yet to be cultivated in vitro. We employed a combination of high-density phylogenetic 16S rDNA microarray and 16S rDNA clone library sequencing to determine the microbial community composition of symptomatic and asymptomatic citrus midribs. Our results revealed that citrus leaf midribs can support a diversity of microbes. PhyloChip analysis indicated that 47 orders of bacteria from 15 phyla were present in the citrus leaf midribs while 20 orders from phyla were observed with the cloning and sequencing method. PhyloChip arrays indicated that nine taxa were significantly more abundant in symptomatic midribs compared to asymptomatic midribs. Candidatus Liberibacter asiaticus (Las) was detected at a very low level in asymptomatic plants, but was over 200 times more abundant in symptomatic plants. The PhyloChip analysis was further verified by sequencing 16S rDNA clone libraries, which indicated the dominance of Las in symptomatic leaves. These data implicate Las as the pathogen responsible for HLB disease. Citrus is the most important commercial fruit crop in Florida. In recent years, citrus Huanglongbing (HLB), also called citrus greening, has severely affected Florida's citrus production and hence has drawn an enormous amount of attention. HLB is one of the most devastating diseases of citrus (6,13), characterized by blotchy mottling with green islands on leaves, as well as stunting, fruit decline, and small, lopsided fruits with poor coloration. The disease tends to be associated with a phloem-limited fastidious {alpha}-proteobacterium given a provisional Candidatus status (Candidatus Liberobacter spp. later changed to Candidatus Liberibacter spp.) in nomenclature (18,25,34). Previous studies indicate that HLB infection causes disorder in the phloem and severely impairs the translocation of assimilates in host plants (5,27,40). Tatineni and colleagues discovered that the HLB bacteria were unevenly distributed in phloem of bark tissue, vascular tissue of the leaf midrib, roots, and different floral and fruit parts (43). Unsuccessful attempts in culturing the pathogen are notably hampering efforts to understand its biology and pathogenesis mechanism. Using a modified Koch's Postulates approach, Jagoueix and colleagues were able to re-infect periwinkle plants from a mixed microbial community harvested from HLB diseased plants (25). Emergence of the disease in otherwise healthy plants led to the conclusion that HLB was associated with Candidatus Liberibacter sp. based on its 16S rDNA sequence (18,25). Currently, three species of the pathogen are recognized from trees with HLB disease based on 16S rDNA sequence: Ca. Liberibacter asiaticus (Las), Ca. Liberibacter africanus (Laf), and Ca. Liberibacter americanus (Lam); Las is the most prevalent species among HLB diseased trees (5,12,18,25,44). Las is naturally transmitted to citrus by the psyllid, Diaphorina citri Kuwayama, and can be artificially transmitted by grafting from citrus to citrus and dodder (Cuscuta campestris) to periwinkle (Catharanthus roseus) or tobacco (Nicotiana tabacum Xanthi) (5). Based on current research regarding the associations of Liberibacter in planta there is not enough evidence to implicate Liberibacter as the definitive causal agent of HLB disease due to its resistance to cultivation in vitro. It is possible that HLB disease may be the result of complex etiology where Liberibacter interacts with other endophytic bacteria. However, there is not enough evidence regarding its association(s) in planta to make this conclusion, nor is it known whether associated microbial communities play a role in expression of pathogenic traits. The main objective of the study was to test the hypothesis that other bacteria besides Ca. Liberibacter spp. are associated with citrus greening disease. The differences between the relative abundance, species richness and phylogenetic diversity of the microbial communitie