Science.gov

Sample records for 10-5 msun yr-1

  1. Separation in 5 Msun Binaries

    NASA Astrophysics Data System (ADS)

    Evans, Nancy R.; Bond, H. E.; Schaefer, G.; Mason, B. D.; Karovska, M.; Tingle, E.

    2013-01-01

    Cepheids (5 Msun stars) provide an excellent sample for determining the binary properties of fairly massive stars. International Ultraviolet Explorer (IUE) observations of Cepheids brighter than 8th magnitude resulted in a list of ALL companions more massive than 2.0 Msun uniformly sensitive to all separations. Hubble Space Telescope Wide Field Camera 3 (WFC3) has resolved three of these binaries (Eta Aql, S Nor, and V659 Cen). Combining these separations with orbital data in the literature, we derive an unbiased distribution of binary separations for a sample of 18 Cepheids, and also a distribution of mass ratios. The distribution of orbital periods shows that the 5 Msun binaries prefer shorter periods than 1 Msun stars, reflecting differences in star formation processes.

  2. A Turn-over in the Galaxy Main Sequence of Star Formation at M* ~ 1010 Msun

    NASA Astrophysics Data System (ADS)

    Lee, Nicholas; Cosmos Team

    2015-01-01

    The relationship between galaxy star formation rates (SFR) and stellar masses (M*) is re-examined using a mass-selected sample of ~62,000 star-forming galaxies at z < 1.3 in the COSMOS 2 deg2 field. We measure infrared luminosities and SFRs using photometry from Herschel-PACS and SPIRE, Spitzer 24 μm, and the NRK method based on galaxies' locations in the restframe color-color diagram (NUV-r) vs. (r-K). Using these new SFRs, we find that the relationship between median SFR and M* follows a power-law at low stellar masses, but flattens to nearly constant SFR at high stellar masses. We describe a new parameterization that provides the best fit to the main sequence and charaterizes the low mass power-law slope, turnover mass, and overall scaling of the relationship. The turnover in the main sequence occurs at a characteristic mass of about M0 ~ 1010 Msun at all redshifts. The low mass power-law slope ranges from 0.9-1.3 and the overall scaling of the main sequence rises as a function of (1+z)4.2±0.10. A broken power-law fit below and above the turnover mass gives relationships of SFR ∝ M*0.88±0.06 below the turnover mass and SFR ∝ M*0.27±0.04 above the turnover mass. On average, galaxies more massive than M* > 1010 Msun have a much lower specfic star formation rate (SSFR = SFR/M*) than would be expected by simply extrapolating the traditional linear fit to the main sequence found for less massive galaxies.

  3. 10 CFR 10.5 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Definitions. 10.5 Section 10.5 Energy NUCLEAR REGULATORY COMMISSION CRITERIA AND PROCEDURES FOR DETERMINING ELIGIBILITY FOR ACCESS TO RESTRICTED DATA OR NATIONAL SECURITY INFORMATION OR AN EMPLOYMENT CLEARANCE General Provisions § 10.5 Definitions. Access authorization means an administrative...

  4. 10 CFR 10.5 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Definitions. 10.5 Section 10.5 Energy NUCLEAR REGULATORY COMMISSION CRITERIA AND PROCEDURES FOR DETERMINING ELIGIBILITY FOR ACCESS TO RESTRICTED DATA OR NATIONAL SECURITY INFORMATION OR AN EMPLOYMENT CLEARANCE General Provisions § 10.5 Definitions. Access authorization means an administrative...

  5. 10 CFR 10.5 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Definitions. 10.5 Section 10.5 Energy NUCLEAR REGULATORY COMMISSION CRITERIA AND PROCEDURES FOR DETERMINING ELIGIBILITY FOR ACCESS TO RESTRICTED DATA OR NATIONAL SECURITY INFORMATION OR AN EMPLOYMENT CLEARANCE General Provisions § 10.5 Definitions. Access authorization means an administrative...

  6. 46 CFR 56.10-5 - Pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Pipe. 56.10-5 Section 56.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Components... design limits of stress and temperature indicated in ASME B31.1 (incorporated by reference; see 46 CFR...

  7. 46 CFR 56.10-5 - Pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Pipe. 56.10-5 Section 56.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Components... design limits of stress and temperature indicated in ASME B31.1 (incorporated by reference; see 46 CFR...

  8. 44 CFR 10.5 - Responsibilities.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 44 Emergency Management and Assistance 1 2012-10-01 2011-10-01 true Responsibilities. 10.5 Section... SECURITY GENERAL ENVIRONMENTAL CONSIDERATIONS Agency Implementing Procedures § 10.5 Responsibilities. (a... impact statements and assign lead agency responsibility when more than one FEMA office or...

  9. 10 CFR 10.5 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Definitions. 10.5 Section 10.5 Energy NUCLEAR REGULATORY COMMISSION CRITERIA AND PROCEDURES FOR DETERMINING ELIGIBILITY FOR ACCESS TO RESTRICTED DATA OR NATIONAL... Information Officer, is eligible for a security clearance for access to Restricted Data or National...

  10. 32 CFR 10.5 - Construction.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... with 32 CFR part 9, and Military Order of November 13, 2001, “Detention, Treatment, and Trial of... event of an inconsistency, the provisions of 32 CFR part 9, and Military Order of November 13, 2001... 32 National Defense 1 2014-07-01 2014-07-01 false Construction. 10.5 Section 10.5 National...

  11. 32 CFR 10.5 - Construction.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... with 32 CFR part 9, and Military Order of November 13, 2001, “Detention, Treatment, and Trial of... event of an inconsistency, the provisions of 32 CFR part 9, and Military Order of November 13, 2001... 32 National Defense 1 2012-07-01 2012-07-01 false Construction. 10.5 Section 10.5 National...

  12. 44 CFR 10.5 - Responsibilities.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 44 Emergency Management and Assistance 1 2013-10-01 2013-10-01 false Responsibilities. 10.5... Responsibilities. (a) The Regional Administrators shall, for each action not categorically excluded from this... impact statements and assign lead agency responsibility when more than one FEMA office or...

  13. 44 CFR 10.5 - Responsibilities.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Responsibilities. 10.5... Responsibilities. (a) The Regional Administrators shall, for each action not categorically excluded from this... impact statements and assign lead agency responsibility when more than one FEMA office or...

  14. 46 CFR 59.10-5 - Cracks.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... CFR 59.01-2). For thicknesses exceeding three-fourths inch, suitable U grooves should be employed. A... APPURTENANCES Welding Repairs to Boilers and Pressure Vessels in -Service § 59.10-5 Cracks. (a) Cracks extending... corrugated furnaces may be repaired by welding provided any one crack does not exceed 20 inches in length....

  15. 46 CFR 59.10-5 - Cracks.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... CFR 59.01-2). For thicknesses exceeding three-fourths inch, suitable U grooves should be employed. A... APPURTENANCES Welding Repairs to Boilers and Pressure Vessels in -Service § 59.10-5 Cracks. (a) Cracks extending... corrugated furnaces may be repaired by welding provided any one crack does not exceed 20 inches in length....

  16. 46 CFR 59.10-5 - Cracks.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... CFR 59.01-2). For thicknesses exceeding three-fourths inch, suitable U grooves should be employed. A... APPURTENANCES Welding Repairs to Boilers and Pressure Vessels in -Service § 59.10-5 Cracks. (a) Cracks extending... corrugated furnaces may be repaired by welding provided any one crack does not exceed 20 inches in length....

  17. 46 CFR 59.10-5 - Cracks.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... CFR 59.01-2). For thicknesses exceeding three-fourths inch, suitable U grooves should be employed. A... APPURTENANCES Welding Repairs to Boilers and Pressure Vessels in -Service § 59.10-5 Cracks. (a) Cracks extending... corrugated furnaces may be repaired by welding provided any one crack does not exceed 20 inches in length....

  18. 46 CFR 59.10-5 - Cracks.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... CFR 59.01-2). For thicknesses exceeding three-fourths inch, suitable U grooves should be employed. A... APPURTENANCES Welding Repairs to Boilers and Pressure Vessels in -Service § 59.10-5 Cracks. (a) Cracks extending... corrugated furnaces may be repaired by welding provided any one crack does not exceed 20 inches in length....

  19. 46 CFR 61.10-5 - Pressure vessels in service.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Pressure vessels in service. 61.10-5 Section 61.10-5... INSPECTIONS Tests and Inspections of Pressure Vessels § 61.10-5 Pressure vessels in service. (a) Basic requirements. Each pressure vessel must be examined or tested every 5 years. The extent of the test...

  20. 46 CFR 61.10-5 - Pressure vessels in service.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Pressure vessels in service. 61.10-5 Section 61.10-5... INSPECTIONS Tests and Inspections of Pressure Vessels § 61.10-5 Pressure vessels in service. (a) Basic requirements. Each pressure vessel must be examined or tested every 5 years. The extent of the test...

  1. 46 CFR 61.10-5 - Pressure vessels in service.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Pressure vessels in service. 61.10-5 Section 61.10-5... INSPECTIONS Tests and Inspections of Pressure Vessels § 61.10-5 Pressure vessels in service. (a) Basic requirements. Each pressure vessel must be examined or tested every 5 years. The extent of the test...

  2. 46 CFR 61.10-5 - Pressure vessels in service.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Pressure vessels in service. 61.10-5 Section 61.10-5... INSPECTIONS Tests and Inspections of Pressure Vessels § 61.10-5 Pressure vessels in service. (a) Basic requirements. Each pressure vessel must be examined or tested every 5 years. The extent of the test...

  3. 46 CFR 61.10-5 - Pressure vessels in service.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Pressure vessels in service. 61.10-5 Section 61.10-5... INSPECTIONS Tests and Inspections of Pressure Vessels § 61.10-5 Pressure vessels in service. (a) Basic requirements. Each pressure vessel must be examined or tested every 5 years. The extent of the test...

  4. 46 CFR 113.10-5 - Common return.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Common return. 113.10-5 Section 113.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Fire and Smoke Detecting and Alarm Systems § 113.10-5 Common return. A...

  5. 46 CFR 113.10-5 - Common return.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Common return. 113.10-5 Section 113.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Fire and Smoke Detecting and Alarm Systems § 113.10-5 Common return. A...

  6. 46 CFR 113.10-5 - Common return.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Common return. 113.10-5 Section 113.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Fire and Smoke Detecting and Alarm Systems § 113.10-5 Common return. A...

  7. 46 CFR 113.10-5 - Common return.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Common return. 113.10-5 Section 113.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Fire and Smoke Detecting and Alarm Systems § 113.10-5 Common return. A...

  8. 46 CFR 113.10-5 - Common return.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Common return. 113.10-5 Section 113.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Fire and Smoke Detecting and Alarm Systems § 113.10-5 Common return. A...

  9. 46 CFR 92.10-5 - Two means required.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Two means required. 92.10-5 Section 92.10-5 Shipping... AND ARRANGEMENT Means of Escape § 92.10-5 Two means required. (a) There shall be at least two means of... quartered or normally employed. At least one of these two means of escape shall be independent of...

  10. 46 CFR 76.10-5 - Fire pumps.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 3 2013-10-01 2013-10-01 false Fire pumps. 76.10-5 Section 76.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PASSENGER VESSELS FIRE PROTECTION EQUIPMENT Fire Main System, Details § 76.10-5 Fire pumps. (a) Vessels shall be equipped with independently driven fire pumps...

  11. 46 CFR 95.10-5 - Fire pumps.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Fire pumps. 95.10-5 Section 95.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS FIRE PROTECTION EQUIPMENT Fire Main System, Details § 95.10-5 Fire pumps. (a) Vessels shall be equipped with independently driven...

  12. 46 CFR 95.10-5 - Fire pumps.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Fire pumps. 95.10-5 Section 95.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS FIRE PROTECTION EQUIPMENT Fire Main System, Details § 95.10-5 Fire pumps. (a) Vessels shall be equipped with independently driven...

  13. 46 CFR 95.10-5 - Fire pumps.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Fire pumps. 95.10-5 Section 95.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS FIRE PROTECTION EQUIPMENT Fire Main System, Details § 95.10-5 Fire pumps. (a) Vessels shall be equipped with independently driven...

  14. 46 CFR 193.10-5 - Fire pumps.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Fire pumps. 193.10-5 Section 193.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS FIRE PROTECTION EQUIPMENT Fire Main System, Details § 193.10-5 Fire pumps. (a) Vessels shall be equipped with...

  15. 46 CFR 76.10-5 - Fire pumps.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 3 2014-10-01 2014-10-01 false Fire pumps. 76.10-5 Section 76.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PASSENGER VESSELS FIRE PROTECTION EQUIPMENT Fire Main System, Details § 76.10-5 Fire pumps. (a) Vessels shall be equipped with independently driven fire pumps...

  16. 46 CFR 76.10-5 - Fire pumps.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 3 2012-10-01 2012-10-01 false Fire pumps. 76.10-5 Section 76.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PASSENGER VESSELS FIRE PROTECTION EQUIPMENT Fire Main System, Details § 76.10-5 Fire pumps. (a) Vessels shall be equipped with independently driven fire pumps...

  17. 46 CFR 95.10-5 - Fire pumps.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Fire pumps. 95.10-5 Section 95.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS FIRE PROTECTION EQUIPMENT Fire Main System, Details § 95.10-5 Fire pumps. (a) Vessels shall be equipped with independently driven...

  18. 46 CFR 95.10-5 - Fire pumps.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Fire pumps. 95.10-5 Section 95.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS FIRE PROTECTION EQUIPMENT Fire Main System, Details § 95.10-5 Fire pumps. (a) Vessels shall be equipped with independently driven...

  19. 46 CFR 30.10-5 - Cargo-TB/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Cargo-TB/ALL. 30.10-5 Section 30.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5 Cargo—TB/ALL. The term cargo means combustible liquid, flammable liquid, or liquefied flammable gas...

  20. 46 CFR 30.10-5 - Cargo-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Cargo-TB/ALL. 30.10-5 Section 30.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5 Cargo—TB/ALL. The term cargo means combustible liquid, flammable liquid, or liquefied flammable gas...

  1. 46 CFR 30.10-5 - Cargo-TB/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Cargo-TB/ALL. 30.10-5 Section 30.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5 Cargo—TB/ALL. The term cargo means combustible liquid, flammable liquid, or liquefied flammable gas...

  2. 46 CFR 97.10-5 - Persons excluded.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Persons excluded. 97.10-5 Section 97.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS OPERATIONS Persons Allowed in Pilothouse and on Navigation Bridge § 97.10-5 Persons excluded. Masters and pilots...

  3. 46 CFR 97.10-5 - Persons excluded.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Persons excluded. 97.10-5 Section 97.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS OPERATIONS Persons Allowed in Pilothouse and on Navigation Bridge § 97.10-5 Persons excluded. Masters and pilots...

  4. 46 CFR 97.10-5 - Persons excluded.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Persons excluded. 97.10-5 Section 97.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS OPERATIONS Persons Allowed in Pilothouse and on Navigation Bridge § 97.10-5 Persons excluded. Masters and pilots...

  5. 46 CFR 97.10-5 - Persons excluded.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Persons excluded. 97.10-5 Section 97.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS OPERATIONS Persons Allowed in Pilothouse and on Navigation Bridge § 97.10-5 Persons excluded. Masters and pilots...

  6. 33 CFR 66.10-5-66.10-10 - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false 66.10-5-66.10-10 Section 66.10-5-66.10-10 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Uniform State Waterway Marking System §§ 66.10-5—66.10-10...

  7. 33 CFR 66.10-5-66.10-10 - [Reserved

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false 66.10-5-66.10-10 Section 66.10-5-66.10-10 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Uniform State Waterway Marking System §§ 66.10-5—66.10-10...

  8. 46 CFR 111.10-5 - Multiple energy sources.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Multiple energy sources. 111.10-5 Section 111.10-5...-GENERAL REQUIREMENTS Power Supply § 111.10-5 Multiple energy sources. Failure of any single generating set energy source such as a boiler, diesel, gas turbine, or steam turbine must not cause all generating...

  9. 46 CFR 111.10-5 - Multiple energy sources.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Multiple energy sources. 111.10-5 Section 111.10-5...-GENERAL REQUIREMENTS Power Supply § 111.10-5 Multiple energy sources. Failure of any single generating set energy source such as a boiler, diesel, gas turbine, or steam turbine must not cause all generating...

  10. 46 CFR 111.10-5 - Multiple energy sources.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Multiple energy sources. 111.10-5 Section 111.10-5...-GENERAL REQUIREMENTS Power Supply § 111.10-5 Multiple energy sources. Failure of any single generating set energy source such as a boiler, diesel, gas turbine, or steam turbine must not cause all generating...

  11. 46 CFR 111.10-5 - Multiple energy sources.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Multiple energy sources. 111.10-5 Section 111.10-5...-GENERAL REQUIREMENTS Power Supply § 111.10-5 Multiple energy sources. Failure of any single generating set energy source such as a boiler, diesel, gas turbine, or steam turbine must not cause all generating...

  12. 46 CFR 111.10-5 - Multiple energy sources.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Multiple energy sources. 111.10-5 Section 111.10-5...-GENERAL REQUIREMENTS Power Supply § 111.10-5 Multiple energy sources. Failure of any single generating set energy source such as a boiler, diesel, gas turbine, or steam turbine must not cause all generating...

  13. 46 CFR 30.10-5 - Cargo-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Cargo-TB/ALL. 30.10-5 Section 30.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5 Cargo—TB/ALL. The term cargo means combustible liquid, flammable liquid, or liquefied flammable gas...

  14. 46 CFR 168.10-5 - Civilian nautical school.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Civilian nautical school. 168.10-5 Section 168.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS CIVILIAN NAUTICAL SCHOOL VESSELS Definitions of Terms Used in This Part § 168.10-5 Civilian nautical school. The term...

  15. 46 CFR 72.10-5 - Two means required.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 3 2011-10-01 2011-10-01 false Two means required. 72.10-5 Section 72.10-5 Shipping... Means of Escape § 72.10-5 Two means required. (a) There shall be at least two means of escape from all... least one of these two means of escape shall be independent of watertight doors. For stairway...

  16. 46 CFR 92.10-5 - Two means required.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Two means required. 92.10-5 Section 92.10-5 Shipping... AND ARRANGEMENT Means of Escape § 92.10-5 Two means required. (a) There shall be at least two means of... quartered or normally employed. At least one of these two means of escape shall be independent of...

  17. 46 CFR 190.10-5 - Two means required.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Two means required. 190.10-5 Section 190.10-5 Shipping... ARRANGEMENT Means of Escape § 190.10-5 Two means required. (a) There shall be at least two means of escape... least one of these two means of escape shall be independent of watertight doors and hatches, except...

  18. 46 CFR 190.10-5 - Two means required.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Two means required. 190.10-5 Section 190.10-5 Shipping... ARRANGEMENT Means of Escape § 190.10-5 Two means required. (a) There shall be at least two means of escape... least one of these two means of escape shall be independent of watertight doors and hatches, except...

  19. 46 CFR 72.10-5 - Two means required.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 3 2013-10-01 2013-10-01 false Two means required. 72.10-5 Section 72.10-5 Shipping... Means of Escape § 72.10-5 Two means required. (a) There shall be at least two means of escape from all... least one of these two means of escape shall be independent of watertight doors. For stairway...

  20. 46 CFR 190.10-5 - Two means required.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Two means required. 190.10-5 Section 190.10-5 Shipping... ARRANGEMENT Means of Escape § 190.10-5 Two means required. (a) There shall be at least two means of escape... least one of these two means of escape shall be independent of watertight doors and hatches, except...

  1. 46 CFR 92.10-5 - Two means required.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Two means required. 92.10-5 Section 92.10-5 Shipping... AND ARRANGEMENT Means of Escape § 92.10-5 Two means required. (a) There shall be at least two means of... quartered or normally employed. At least one of these two means of escape shall be independent of...

  2. 46 CFR 72.10-5 - Two means required.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 3 2012-10-01 2012-10-01 false Two means required. 72.10-5 Section 72.10-5 Shipping... Means of Escape § 72.10-5 Two means required. (a) There shall be at least two means of escape from all... least one of these two means of escape shall be independent of watertight doors. For stairway...

  3. 46 CFR 190.10-5 - Two means required.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Two means required. 190.10-5 Section 190.10-5 Shipping... ARRANGEMENT Means of Escape § 190.10-5 Two means required. (a) There shall be at least two means of escape... least one of these two means of escape shall be independent of watertight doors and hatches, except...

  4. 46 CFR 72.10-5 - Two means required.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 3 2014-10-01 2014-10-01 false Two means required. 72.10-5 Section 72.10-5 Shipping... Means of Escape § 72.10-5 Two means required. (a) There shall be at least two means of escape from all... least one of these two means of escape shall be independent of watertight doors. For stairway...

  5. 46 CFR 72.10-5 - Two means required.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Two means required. 72.10-5 Section 72.10-5 Shipping... Means of Escape § 72.10-5 Two means required. (a) There shall be at least two means of escape from all... least one of these two means of escape shall be independent of watertight doors. For stairway...

  6. 46 CFR 92.10-5 - Two means required.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Two means required. 92.10-5 Section 92.10-5 Shipping... AND ARRANGEMENT Means of Escape § 92.10-5 Two means required. (a) There shall be at least two means of... quartered or normally employed. At least one of these two means of escape shall be independent of...

  7. 46 CFR 190.10-5 - Two means required.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Two means required. 190.10-5 Section 190.10-5 Shipping... ARRANGEMENT Means of Escape § 190.10-5 Two means required. (a) There shall be at least two means of escape... least one of these two means of escape shall be independent of watertight doors and hatches, except...

  8. 46 CFR 30.10-5 - Cargo-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Cargo-TB/ALL. 30.10-5 Section 30.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5 Cargo—TB/ALL. The term cargo means combustible liquid, flammable liquid, or liquefied flammable gas...

  9. 46 CFR 193.10-5 - Fire main system, details.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... of a total flooding system using carbon dioxide or a clean agent complying with 46 CFR subpart 95.16... 46 Shipping 7 2012-10-01 2012-10-01 false Fire main system, details. 193.10-5 Section 193.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS...

  10. 46 CFR 58.10-5 - Gasoline engine installations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... MACHINERY AND RELATED SYSTEMS Internal Combustion Engine Installations § 58.10-5 Gasoline engine installations. (a) Engine design. All installations shall be of marine type engines suitable for the intended... 46 Shipping 2 2010-10-01 2010-10-01 false Gasoline engine installations. 58.10-5 Section...

  11. 46 CFR 151.10-5 - Subdivision and stability.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Subdivision and stability. 151.10-5 Section 151.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES... and stability. Each barge must meet the applicable requirements in subchapter S of this chapter....

  12. 46 CFR 151.10-5 - Subdivision and stability.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Subdivision and stability. 151.10-5 Section 151.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES... and stability. Each barge must meet the applicable requirements in subchapter S of this chapter....

  13. 46 CFR 151.10-5 - Subdivision and stability.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Subdivision and stability. 151.10-5 Section 151.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES... and stability. Each barge must meet the applicable requirements in subchapter S of this chapter....

  14. 46 CFR 151.10-5 - Subdivision and stability.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Subdivision and stability. 151.10-5 Section 151.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES... and stability. Each barge must meet the applicable requirements in subchapter S of this chapter....

  15. 46 CFR 151.10-5 - Subdivision and stability.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Subdivision and stability. 151.10-5 Section 151.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES... and stability. Each barge must meet the applicable requirements in subchapter S of this chapter....

  16. 33 CFR 49.10-5 - Payment of moneys due.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Payment of moneys due. 49.10-5... PAYMENT OF AMOUNTS DUE MENTALLY INCOMPETENT COAST GUARD PERSONNEL Reports and Moneys § 49.10-5 Payment of moneys due. Upon the appointment of a trustee or trustees to receive moneys due an incompetent,...

  17. 33 CFR 49.10-5 - Payment of moneys due.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Payment of moneys due. 49.10-5... PAYMENT OF AMOUNTS DUE MENTALLY INCOMPETENT COAST GUARD PERSONNEL Reports and Moneys § 49.10-5 Payment of moneys due. Upon the appointment of a trustee or trustees to receive moneys due an incompetent,...

  18. 33 CFR 49.10-5 - Payment of moneys due.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Payment of moneys due. 49.10-5... PAYMENT OF AMOUNTS DUE MENTALLY INCOMPETENT COAST GUARD PERSONNEL Reports and Moneys § 49.10-5 Payment of moneys due. Upon the appointment of a trustee or trustees to receive moneys due an incompetent,...

  19. 33 CFR 49.10-5 - Payment of moneys due.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Payment of moneys due. 49.10-5... PAYMENT OF AMOUNTS DUE MENTALLY INCOMPETENT COAST GUARD PERSONNEL Reports and Moneys § 49.10-5 Payment of moneys due. Upon the appointment of a trustee or trustees to receive moneys due an incompetent,...

  20. 33 CFR 49.10-5 - Payment of moneys due.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Payment of moneys due. 49.10-5... PAYMENT OF AMOUNTS DUE MENTALLY INCOMPETENT COAST GUARD PERSONNEL Reports and Moneys § 49.10-5 Payment of moneys due. Upon the appointment of a trustee or trustees to receive moneys due an incompetent,...

  1. 33 CFR 67.10-5 - Location requirements.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Location requirements. 67.10-5 Section 67.10-5 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES General Requirements for...

  2. 27 CFR 10.5 - Delegations of the Administrator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Administrator's Authorities in 27 CFR Part 10, Commercial Bribery. You may obtain a copy of this order by..., DEPARTMENT OF THE TREASURY LIQUORS COMMERCIAL BRIBERY Scope of Regulations § 10.5 Delegations of...

  3. Evolution of X-ray activity of 1-3 Msun late-type stars in early post-main-sequence phases

    NASA Astrophysics Data System (ADS)

    Pizzolato, N.; Maggio, A.; Sciortino, S.

    2000-09-01

    We have investigated the variation of coronal X-ray emission during early post-main-sequence phases for a sample of 120 late-type stars within 100 pc, and with estimated masses in the range 1-3 Msun, based on Hipparcos parallaxes and recent evolutionary models. These stars were observed with the ROSAT/PSPC, and the data processed with the Palermo-CfA pipeline, including detection and evaluation of X-ray fluxes (or upper limits) by means of a wavelet transform algorithm. We have studied the evolutionary history of X-ray luminosity and surface flux for stars in selected mass ranges, including stars with inactive A-type progenitors on the main sequence and lower mass solar-type stars. Our stellar sample suggests a trend of increasing X-ray emission level with age for stars with masses M > 1.5 Msun, and a decline for lower-mass stars. A similar behavior holds for the average coronal temperature, which follows a power-law correlation with the X-ray luminosity, independently of their mass and evolutionary state. We have also studied the relationship between X-ray luminosity and surface rotation rate for stars in the same mass ranges, and how this relationships departs from the Lx ~ vrot2 law followed by main-sequence stars. Our results are interpreted in terms of a magnetic dynamo whose efficiency depends on the stellar evolutionary state through the mass-dependent changes of the stellar internal structure, including the properties of envelope convection and the internal rotation profile.

  4. 28 CFR 10.5 - Incorporation of papers previously filed.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 1 2011-07-01 2011-07-01 false Incorporation of papers previously filed... CARRYING ON ACTIVITIES WITHIN THE UNITED STATES Registration Statement § 10.5 Incorporation of papers previously filed. Papers and documents already filed with the Attorney General pursuant to the said act...

  5. 15 CFR 10.5 - Development of a recommended standard.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... DEVELOPMENT OF VOLUNTARY PRODUCT STANDARDS § 10.5 Development of a recommended standard. (a) The Standard... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Development of a recommended standard... proposal meets the requirements set forth in § 10.3(a), it may recommend to the Department that...

  6. 15 CFR 10.5 - Development of a recommended standard.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 15 Commerce and Foreign Trade 1 2011-01-01 2011-01-01 false Development of a recommended standard... DEVELOPMENT OF VOLUNTARY PRODUCT STANDARDS § 10.5 Development of a recommended standard. (a) The Standard... Department or the chairman of this committee. If conducted by the chairman, a report of the vote shall...

  7. 28 CFR 10.5 - Incorporation of papers previously filed.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Incorporation of papers previously filed... CARRYING ON ACTIVITIES WITHIN THE UNITED STATES Registration Statement § 10.5 Incorporation of papers previously filed. Papers and documents already filed with the Attorney General pursuant to the said act...

  8. 46 CFR 194.10-5 - Type and location.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... requirements of 49 CFR part 176. (c) Magazine chests. (1) Magazine chests shall be located on the weather decks... utilized shall not be used for stowage of other hazardous materials covered by 49 CFR parts 171-179. The..., AND CONTROL OF EXPLOSIVES AND OTHER HAZARDOUS MATERIALS Magazines § 194.10-5 Type and location....

  9. 46 CFR 194.10-5 - Type and location.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... requirements of 49 CFR part 176. (c) Magazine chests. (1) Magazine chests shall be located on the weather decks... utilized shall not be used for stowage of other hazardous materials covered by 49 CFR parts 171-179. The..., AND CONTROL OF EXPLOSIVES AND OTHER HAZARDOUS MATERIALS Magazines § 194.10-5 Type and location....

  10. 46 CFR 194.10-5 - Type and location.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... requirements of 49 CFR part 176. (c) Magazine chests. (1) Magazine chests shall be located on the weather decks... utilized shall not be used for stowage of other hazardous materials covered by 49 CFR parts 171-179. The..., AND CONTROL OF EXPLOSIVES AND OTHER HAZARDOUS MATERIALS Magazines § 194.10-5 Type and location....

  11. 28 CFR 10.5 - Incorporation of papers previously filed.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 1 2012-07-01 2012-07-01 false Incorporation of papers previously filed... CARRYING ON ACTIVITIES WITHIN THE UNITED STATES Registration Statement § 10.5 Incorporation of papers previously filed. Papers and documents already filed with the Attorney General pursuant to the said act...

  12. 28 CFR 10.5 - Incorporation of papers previously filed.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 1 2013-07-01 2013-07-01 false Incorporation of papers previously filed... CARRYING ON ACTIVITIES WITHIN THE UNITED STATES Registration Statement § 10.5 Incorporation of papers previously filed. Papers and documents already filed with the Attorney General pursuant to the said act...

  13. 28 CFR 10.5 - Incorporation of papers previously filed.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 1 2014-07-01 2014-07-01 false Incorporation of papers previously filed... CARRYING ON ACTIVITIES WITHIN THE UNITED STATES Registration Statement § 10.5 Incorporation of papers previously filed. Papers and documents already filed with the Attorney General pursuant to the said act...

  14. 46 CFR 34.10-5 - Fire pumps-T/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Fire pumps-T/ALL. 34.10-5 Section 34.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS FIREFIGHTING EQUIPMENT Fire Main System, Details § 34.10-5 Fire pumps—T/ALL. (a) Tankships shall be equipped with independently driven fire pumps...

  15. 46 CFR 34.10-5 - Fire pumps-T/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Fire pumps-T/ALL. 34.10-5 Section 34.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS FIREFIGHTING EQUIPMENT Fire Main System, Details § 34.10-5 Fire pumps—T/ALL. (a) Tankships shall be equipped with independently driven fire pumps...

  16. 46 CFR 34.10-5 - Fire pumps-T/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Fire pumps-T/ALL. 34.10-5 Section 34.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS FIREFIGHTING EQUIPMENT Fire Main System, Details § 34.10-5 Fire pumps—T/ALL. (a) Tankships shall be equipped with independently driven fire pumps...

  17. 46 CFR 31.10-5 - Inspection of new tank vessels-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Inspection of new tank vessels-TB/ALL. 31.10-5 Section 31.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS INSPECTION AND CERTIFICATION Inspections § 31.10-5 Inspection of new tank vessels—TB/ALL. (a) Plans. Triplicate copies...

  18. 33 CFR 1.10-5 - Public availability of records and documents.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... and documents. 1.10-5 Section 1.10-5 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY GENERAL GENERAL PROVISIONS Public Availability of Information § 1.10-5 Public..., 2100 2nd St. SW., Stop 7101, Washington, DC 20593-7101. (b) Each person desiring to inspect a record...

  19. 46 CFR 30.10-5b - Cargo control station-TB/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Cargo control station-TB/ALL. 30.10-5b Section 30.10-5b Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5b Cargo control station—TB/ALL. The term cargo control station means a location that is...

  20. 46 CFR 30.10-5b - Cargo control station-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Cargo control station-TB/ALL. 30.10-5b Section 30.10-5b Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5b Cargo control station—TB/ALL. The term cargo control station means a location that is...

  1. 46 CFR 30.10-5b - Cargo control station-TB/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Cargo control station-TB/ALL. 30.10-5b Section 30.10-5b Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5b Cargo control station—TB/ALL. The term cargo control station means a location that is...

  2. 46 CFR 30.10-5b - Cargo control station-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Cargo control station-TB/ALL. 30.10-5b Section 30.10-5b Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5b Cargo control station—TB/ALL. The term cargo control station means a location that is...

  3. 46 CFR 50.10-5 - Coast Guard District Commander or District Commander.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Coast Guard District Commander or District Commander. 50.10-5 Section 50.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING GENERAL PROVISIONS Definition of Terms Used in This Subchapter § 50.10-5 Coast Guard...

  4. 46 CFR 50.10-5 - Coast Guard District Commander or District Commander.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Coast Guard District Commander or District Commander. 50.10-5 Section 50.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING GENERAL PROVISIONS Definition of Terms Used in This Subchapter § 50.10-5 Coast Guard...

  5. 46 CFR 50.10-5 - Coast Guard District Commander or District Commander.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Coast Guard District Commander or District Commander. 50.10-5 Section 50.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING GENERAL PROVISIONS Definition of Terms Used in This Subchapter § 50.10-5 Coast Guard...

  6. 46 CFR 50.10-5 - Coast Guard District Commander or District Commander.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Coast Guard District Commander or District Commander. 50.10-5 Section 50.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING GENERAL PROVISIONS Definition of Terms Used in This Subchapter § 50.10-5 Coast Guard...

  7. 46 CFR 50.10-5 - Coast Guard District Commander or District Commander.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Coast Guard District Commander or District Commander. 50.10-5 Section 50.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING GENERAL PROVISIONS Definition of Terms Used in This Subchapter § 50.10-5 Coast Guard...

  8. 46 CFR 30.10-5b - Cargo control station-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Cargo control station-TB/ALL. 30.10-5b Section 30.10-5b Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5b Cargo control station—TB/ALL. The term cargo control station means a location that is...

  9. 46 CFR 38.10-5 - Filling and discharge pipes-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Filling and discharge pipes-TB/ALL. 38.10-5 Section 38.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS LIQUEFIED FLAMMABLE GASES Piping, Valves, Fittings, and Accessory Equipment § 38.10-5 Filling and discharge pipes—TB/ALL. (a) Filling and discharge connections shall be...

  10. 46 CFR 38.10-5 - Filling and discharge pipes-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Filling and discharge pipes-TB/ALL. 38.10-5 Section 38.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS LIQUEFIED FLAMMABLE GASES Piping, Valves, Fittings, and Accessory Equipment § 38.10-5 Filling and discharge pipes—TB/ALL. (a) Filling and discharge connections shall be...

  11. 46 CFR 30.10-5a - Cargo area-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Cargo area-TB/ALL. 30.10-5a Section 30.10-5a Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5a Cargo area—TB/ALL. The term cargo area means that part of a vessel that includes the cargo tanks...

  12. 46 CFR 30.10-5a - Cargo area-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Cargo area-TB/ALL. 30.10-5a Section 30.10-5a Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5a Cargo area—TB/ALL. The term cargo area means that part of a vessel that includes the cargo tanks...

  13. 46 CFR 30.10-5a - Cargo area-TB/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Cargo area-TB/ALL. 30.10-5a Section 30.10-5a Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5a Cargo area—TB/ALL. The term cargo area means that part of a vessel that includes the cargo tanks...

  14. 46 CFR 30.10-5a - Cargo area-TB/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Cargo area-TB/ALL. 30.10-5a Section 30.10-5a Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5a Cargo area—TB/ALL. The term cargo area means that part of a vessel that includes the cargo tanks...

  15. 46 CFR 38.10-5 - Filling and discharge pipes-TB/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Filling and discharge pipes-TB/ALL. 38.10-5 Section 38.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS LIQUEFIED FLAMMABLE GASES Piping, Valves, Fittings, and Accessory Equipment § 38.10-5 Filling and discharge pipes—TB/ALL. (a) Filling and discharge connections shall be...

  16. 46 CFR 38.10-5 - Filling and discharge pipes-TB/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Filling and discharge pipes-TB/ALL. 38.10-5 Section 38.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS LIQUEFIED FLAMMABLE GASES Piping, Valves, Fittings, and Accessory Equipment § 38.10-5 Filling and discharge pipes—TB/ALL. (a) Filling and discharge connections shall be...

  17. 46 CFR 35.10-5 - Muster lists, emergency signals, and manning-T/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Muster lists, emergency signals, and manning-T/ALL. 35.10-5 Section 35.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Fire and Emergency Requirements § 35.10-5 Muster lists, emergency signals, and manning—T/ALL. The requirements for muster lists, emergency signals,...

  18. 46 CFR 35.10-5 - Muster lists, emergency signals, and manning-T/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Muster lists, emergency signals, and manning-T/ALL. 35.10-5 Section 35.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Fire and Emergency Requirements § 35.10-5 Muster lists, emergency signals, and manning—T/ALL. The requirements for muster lists, emergency signals,...

  19. 46 CFR 35.10-5 - Muster lists, emergency signals, and manning-T/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Muster lists, emergency signals, and manning-T/ALL. 35.10-5 Section 35.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Fire and Emergency Requirements § 35.10-5 Muster lists, emergency signals, and manning—T/ALL. The requirements for muster lists, emergency signals,...

  20. 46 CFR 35.10-5 - Muster lists, emergency signals, and manning-T/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Muster lists, emergency signals, and manning-T/ALL. 35.10-5 Section 35.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Fire and Emergency Requirements § 35.10-5 Muster lists, emergency signals, and manning—T/ALL. The requirements for muster lists, emergency signals,...

  1. 46 CFR 35.10-5 - Muster lists, emergency signals, and manning-T/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Muster lists, emergency signals, and manning-T/ALL. 35.10-5 Section 35.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Fire and Emergency Requirements § 35.10-5 Muster lists, emergency signals, and manning—T/ALL. The requirements for muster lists, emergency signals,...

  2. 46 CFR 30.10-5a - Cargo area-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Cargo area-TB/ALL. 30.10-5a Section 30.10-5a Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5a Cargo area—TB/ALL. The term cargo area means that part of a vessel that includes the cargo tanks...

  3. 41 CFR 302-10.5 - May I transport a mobile home over water?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 4 2010-07-01 2010-07-01 false May I transport a mobile home over water? 302-10.5 Section 302-10.5 Public Contracts and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 10-ALLOWANCES FOR TRANSPORTATION OF MOBILE HOMES AND BOATS USED AS...

  4. 41 CFR 302-10.5 - May I transport a mobile home over water?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 41 Public Contracts and Property Management 4 2011-07-01 2011-07-01 false May I transport a mobile home over water? 302-10.5 Section 302-10.5 Public Contracts and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 10-ALLOWANCES...

  5. 41 CFR 302-10.5 - May I transport a mobile home over water?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 41 Public Contracts and Property Management 4 2012-07-01 2012-07-01 false May I transport a mobile home over water? 302-10.5 Section 302-10.5 Public Contracts and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 10-ALLOWANCES FOR TRANSPORTATION OF MOBILE HOMES AND BOATS USED AS...

  6. 33 CFR 1.10-5 - Public availability of records and documents.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... written request to the Chief, Office of Information Management (CG-61), U.S. Coast Guard Headquarters... of Information Management (CG-61), at the address in paragraph (a) of this section. ... HOMELAND SECURITY GENERAL GENERAL PROVISIONS Public Availability of Information § 1.10-5...

  7. 46 CFR 54.10-5 - Maximum allowable working pressure (reproduces UG-98).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... reference; see 46 CFR 54.01-1.) (b) The maximum allowable working pressure for a vessel part is the maximum... loadings listed in UG-22 of section VIII of the ASME Boiler and Pressure Vessel Code (see 46 CFR 54.01-30... ENGINEERING PRESSURE VESSELS Inspection, Reports, and Stamping § 54.10-5 Maximum allowable working...

  8. 33 CFR 1.10-5 - Public availability of records and documents.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... written request to the Chief, Office of Information Management (CG-61), U.S. Coast Guard Headquarters... of Information Management (CG-61), at the address in paragraph (a) of this section. ... HOMELAND SECURITY GENERAL GENERAL PROVISIONS Public Availability of Information § 1.10-5...

  9. 33 CFR 1.10-5 - Public availability of records and documents.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... written request to the Chief, Office of Information Management (CG-61), U.S. Coast Guard Headquarters... of Information Management (CG-61), at the address in paragraph (a) of this section. ... HOMELAND SECURITY GENERAL GENERAL PROVISIONS Public Availability of Information § 1.10-5...

  10. 33 CFR 1.10-5 - Public availability of records and documents.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... written request to the Chief, Office of Information Management (CG-61), U.S. Coast Guard Headquarters... of Information Management (CG-61), at the address in paragraph (a) of this section. ... HOMELAND SECURITY GENERAL GENERAL PROVISIONS Public Availability of Information § 1.10-5...

  11. Evidence for upper Great Lakes waters in the Erie Basin until 10. 5 ka

    SciTech Connect

    Tinkler, K.J. . Dept. of Geology) Lewis, C.F.M. ); Anderson, T.W. ); Cameron, G.D.M.

    1992-01-01

    Modern recession at Niagara Falls suggests that Erie basin flow alone produces a narrower gorge with recession reduced by an order of magnitude. Gorge interpretations relate dimensions to stages of Great Lakes evolution. A published date of 9.8 ka, for upper river shells at Whirlpool State Park favors an interpretation implying 3.5 kilometers of gorge were cut in the period 12.5 ka to 10.5 ka at a rate of 1.75 m/a, a value consistent with the pre-twentieth century rate of 1.37--1.52 m/a. Erie basin discharge alone would be insufficient to excavate the length of gorge seen. Stratigraphic studies of offshore sediments in lake Erie north-east of Long Point based on seismic profiles and core samples show evidence of lake level change. Following decline of the post-Whittlesey (< 13 ka) southwestward-draining proglacial lakes in the Erie basin and the establishment of Lake Iroquois at about 12.5 ka water levels fell to a control on the Niagara Peninsula. Glacial meltwater continued to pass through the Erie basin until 10.5 ka. Negative shifts in delta O-18 suggest increased meltwater flow through the Erie basin and increased lake level between 11 ka and 10.5 ka. An erosional unconformity, lag sediments, and a distinct former shoreface suggest that lake level subsequently fell in the Long Point area of eastern Lake Erie to about 30m below present by about 10.5 ka when meltwater runoff from the upper Great Lakes by-passed Erie basin. Both the lake cores and the gorge recession are consistent with a computational model of flow out to the Erie basin. According to the model great Lakes outflow, augmented by inflow from Lake Agassiz between 11 to 10.5 ka, would yield shorelines at the height attributed to Lake Tonawanda (180--182m), the immediate source of the Niagara River.

  12. NBC's ``10.5'' May Answer An Age-Old Seismologic Question

    NASA Astrophysics Data System (ADS)

    Newman, Andrew V.

    2004-04-01

    There is a new NBC 4-hour miniseries set to air during the May sweeps period (2-3 May) titled simply enough ``10.5.'' No, this is not a sequel to ``9 and ½ weeks'', nor is it a mini-sequel to ``10''. This number instead refers to a mega-earthquake that rocks the west coast of the United States. One may think that the network writers have done their homework and have consulted a geophysicist or two regarding the realism of their program, let alone the title. This is just a short note to comment on their potential folly. I would like to clarify to the network writers, as well as to the non-seismologists in the Earth science community what exactly a magnitude 10.5 earthquake could be, and why, if such were to occur, it may be more than just a west coast problem. Alternatively, NBC may just soon answer an age-old seismologic question...

  13. The rise and fall of Lake Bonneville between 45 and 10.5 ka

    USGS Publications Warehouse

    Benson, L.V.; Lund, S.P.; Smoot, J.P.; Rhode, D.E.; Spencer, R.J.; Verosub, K.L.; Louderback, L.A.; Johnson, C.A.; Rye, R.O.; Negrini, R.M.

    2011-01-01

    A sediment core taken from the western edge of the Bonneville Basin has provided high-resolution proxy records of relative lake-size change for the period 45.1-10.5 calendar ka (hereafter ka). Age control was provided by a paleomagnetic secular variation (PSV)-based age model for Blue Lake core BL04-4. Continuous records of ??18O and total inorganic carbon (TIC) generally match an earlier lake-level envelope based on outcrops and geomorphic features, but with differences in the timing of some hydrologic events/states. The Stansbury Oscillation was found to consist of two oscillations centered on 25 and 24 ka. Lake Bonneville appears to have reached its geomorphic highstand and began spilling at 18.5 ka. The fall from the highstand to the Provo level occurred at 17.0 ka and the lake intermittently overflowed at the Provo level until 15.2 ka, at which time the lake fell again, bottoming out at ~14.7 ka. The lake also fell briefly below the Provo level at ~15.9 ka. Carbonate and ??18O data indicate that between 14.7 and 13.1 ka the lake slowly rose to the Gilbert shoreline and remained at about that elevation until 11.6 ka, when it fell again. Chemical and sedimentological data indicate that a marsh formed in the Blue Lake area at 10.5 ka.Relatively dry periods in the BL04-4 records are associated with Heinrich events H1-H4, suggesting that either the warming that closely followed a Heinrich event increased the evaporation rate in the Bonneville Basin and (or) that the core of the polar jet stream (PJS) shifted north of the Bonneville Basin in response to massive losses of ice from the Laurentide Ice Sheet (LIS) during the Heinrich event. The second Stansbury Oscillation occurred during Heinrich event H2, and the Gilbert wet event occurred during the Younger Dryas cold interval. Several relatively wet events in BL04-4 occur during Dansgaard-Oeschger (DO) warm events.The growth of the Bear River glacier between 32 and 17 ka paralleled changes in the values of proxy

  14. 10.5% efficient polymer and amorphous silicon hybrid tandem photovoltaic cell.

    PubMed

    Kim, Jeehwan; Hong, Ziruo; Li, Gang; Song, Tze-bin; Chey, Jay; Lee, Yun Seog; You, Jingbi; Chen, Chun-Chao; Sadana, Devendra K; Yang, Yang

    2015-01-01

    Thin-film solar cells made with amorphous silicon (a-Si:H) or organic semiconductors are considered as promising renewable energy sources due to their low manufacturing cost and light weight. However, the efficiency of single-junction a-Si:H or organic solar cells is typically <10%, insufficient for achieving grid parity. Here we demonstrate an efficient double-junction photovoltaic cell by employing an a-Si:H film as a front sub-cell and a low band gap polymer:fullerene blend film as a back cell on planar glass substrates. Monolithic integration of 6.0% efficienct a-Si:H and 7.5% efficient polymer:fullerene blend solar cells results in a power conversion efficiency of 10.5%. Such high-efficiency thin-film tandem cells can be achieved by optical management and interface engineering of fully optimized high-performance front and back cells without sacrificing photovoltaic performance in both cells. PMID:25736823

  15. Effect of 10.5 M Aqueous Urea on Helicobacter pylori Urease: A Molecular Dynamics Study.

    PubMed

    Minkara, Mona S; Weaver, Michael N; Merz, Kenneth M

    2015-07-01

    The effects of a 10.5 M solution of aqueous urea on Helicobacter pylori urease were investigated over the course of a 500 ns molecular dynamics (MD) simulation. The enzyme was solvated by 25321 water molecules, and additionally, 4788 urea molecules were added to the solution. Although concentrated urea solutions are known laboratory denaturants, the protein secondary structure is retained throughout the simulation largely because of the short simulation time (urea denaturation occurs on the millisecond time scale). The relatively constant solvent accessible surface area over the last 400 ns of the simulation further confirms the overall lack of denaturation. The wide-open flap state observed previously in Klebsiella areogenes urease [Roberts, B. P., et al. (2012) J. Am. Chem. Soc. 134, 9934] and H. pylori [Minkara, M. S., et al. (2014) J. Chem. Theory Comput. 10, 1852-1862] was also identified in this aqueous urea simulation. Over the course of the trajectory, we were able to observe urea molecules entering the active site in proportions related to the extent of opening of the active site-covering flap. Furthermore, urea molecules were observed to approach the pentacoordinate Ni(2+) ion in position to bind in a manner consistent with the proposed initial coordination step of the hydrolysis mechanism. We also observed a specific and unique pattern in the regions of the protein with a high root-mean-square fluctuation (rmsf). The high-rmsf regions in the β-chain form a horseshoelike arrangement surrounding the active site-covering flap on the surface of the protein. We hypothesize that the function of these regions is to both attract and shuttle urea toward the loop of the active site-covering flap before entry into the cavity. Indeed, urea is observed to interact with these regions for extended periods of simulation time before active site ingress.

  16. Distributed Energy Resources Customer Adoption Model (DER-CAM), Investment & Planing Version 3.10.5.m

    2014-04-01

    Version 3.10.5 is a multi-year Decision Support tool for Distributed Generation (DG). DER-CAM was initially created as an exclusively economic energy model, able to find the cost minimizing combination and operation profile of a set of DER technologies that meet heat and electric loads of a single building or microgrid for a typical test year. Now, version 3.10.5.m solves for a multiple-year horizon the technology choice question, the appropriate capacity for each selected technology asmore » well as the operational and investment schedule. Optimized investment decisions are based on techno-economic criteria, along with site information such as energy loads, economic forecast, and technology characterization. Version 3.10.5 contains: 1. a PV and battery degradation model and 2. variable performance for technologies. Efficiency, investment costs, etc. can vary over time and model technology breakthroughs and advancements.« less

  17. Distributed Energy Resources Customer Adoption Model (DER-CAM), Investment & Planing Version 3.10.5.m

    SciTech Connect

    2014-04-01

    Version 3.10.5 is a multi-year Decision Support tool for Distributed Generation (DG). DER-CAM was initially created as an exclusively economic energy model, able to find the cost minimizing combination and operation profile of a set of DER technologies that meet heat and electric loads of a single building or microgrid for a typical test year. Now, version 3.10.5.m solves for a multiple-year horizon the technology choice question, the appropriate capacity for each selected technology as well as the operational and investment schedule. Optimized investment decisions are based on techno-economic criteria, along with site information such as energy loads, economic forecast, and technology characterization. Version 3.10.5 contains: 1. a PV and battery degradation model and 2. variable performance for technologies. Efficiency, investment costs, etc. can vary over time and model technology breakthroughs and advancements.

  18. Single mode operation with mid-IR hollow fibers in the range 5.1-10.5 µm.

    PubMed

    Sampaolo, Angelo; Patimisco, Pietro; Kriesel, Jason M; Tittel, Frank K; Scamarcio, Gaetano; Spagnolo, Vincenzo

    2015-01-12

    Single mode beam delivery in the mid-infrared spectral range 5.1-10.5 μm employing flexible hollow glass waveguides of 15 cm and 50 cm lengths, with metallic/dielectric internal layers and a bore diameter of 200 μm were demonstrated. Three quantum cascade lasers were coupled with the hollow core fibers. For a fiber length of 15 cm, we measured losses down to 1.55 dB at 5.4 μm and 0.9 dB at 10.5 μm. The influence of the launch conditions in the fiber on the propagation losses and on the beam profile at the waveguide exit was analyzed. At 10.5 µm laser wavelength we found near perfect agreement between measured and theoretical losses, while at ~5 µm and ~6 µm wavelengths the losses were higher than expected. This discrepancy can be explained considering an additional scattering loss effect, which scales as 1/λ(2) and is due to surface roughness of the metallic layer used to form the high-reflective internal layer structure of the hollow core waveguide. PMID:25835666

  19. Probing for MACHOs of Mass 10 -15 Msun to 10 -7 Msun with Gamma-Ray Burst Parallax Spacecraft

    NASA Astrophysics Data System (ADS)

    Nemiroff, Robert J.; Gould, Andrew

    1995-10-01

    Two spacecraft separated by approximately 1 AU and equipped with gamma-ray burst (GRB) detectors could detect or rule out a cosmological density of massive compact halo objects (MACHOs) in the mass range 10^{-15} Msolar <~ M <~ 10^{-7} Msolar , provided that GRBs prove to be cosmological. Previously devised methods for detecting MACHOs have spanned the mass range 10^{-16} Msolar <~ M <~ 107 Msolar , but with a gap of several orders of magnitude near 10^{-9} Msolar . For MACHOs and sources both at a cosmological distance, the Einstein radius is approximately 1 {AU}(M/10^{-7} Msolar)^{1/2} . Hence, if a GRB lies within the Einstein ring of a MACHO of mass M <~ 10^{-7} Msolar as seen by one detector, it will not lie in the Einstein ring as seen by a second detector approximately 1 AU away. This implies that if GRBs are measured to have significantly different fluxes by the two detectors, this would signal the presence of a MACHO <~10^{-7} Msolar . By the same token, if the two detectors measured similar fluxes for several hundred events, a cosmological abundance of such low-mass MACHOs would be ruled out. The lower limit is set by the time resolution tres of the detectors: M <~ 10^{-15} Msolar corresponds to tres <~ 10-2 s. If low-mass MACHOs are detected, there are tests that can discriminate among events generated by MACHOs in the three mass ranges M <~ 10^{-12} Msolar , 10^{-12} Msolar <~ M <~ 10^{-7} Msolar , and M >~ 10^{-7} Msolar . Further experiments would then be required to make more accurate mass measurements.

  20. Quartz-enhanced photoacoustic detection of ethylene using a 10.5 μm quantum cascade laser.

    PubMed

    Wang, Zhen; Li, Zhili; Ren, Wei

    2016-02-22

    A quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor has been developed for the sensitive detection of ethylene (C2H4) at 10.5 µm using a continuous-wave distributed-feedback quantum cascade laser. At this long-wavelength infrared, the key acoustic elements of quartz tuning fork and micro-resonators were optimized to improve the detection signal-to-noise ratio by a factor of >4. The sensor calibration demonstrated an excellent linear response (R2>0.999) to C2H4 concentration at the selected operating pressure of 500 and 760 Torr. With a minimum detection limit of 50 parts per billion (ppb) achieved at an averaging time of 70 s, the sensor has been deployed for measuring the C2H4 efflux during the respiration of biological samples in an agronomic environment.

  1. Spin-Hall-Effect-Assisted Electroresistance in Antiferromagnets via 10(5) A/cm(2) dc Current.

    PubMed

    Han, Jiahao; Wang, Yuyan; Pan, Feng; Song, Cheng

    2016-01-01

    Antiferromagnet (AFM) spintronics with reduced electrical current is greatly expected to process information with high integration and low power consumption. In Pt/FeMn and Ta/FeMn hybrids, we observe significant resistance variation (up to 7% of the total resistance) manipulated by 10(5) A/cm(2) dc current. We have excluded the contribution of isotropic structural effects, and confirmed the critical role of the spin Hall injection from Pt (or Ta) to FeMn. This electrical current-manipulated resistance (i.e. electroresistance) is proposed to be attributed to the spin-Hall-effect-induced spin-orbit torque in FeMn. Similar results have also been detected in plain IrMn films, where the charge current generates spin current via the spin Hall effect with the existence of Ir atoms. All the measurements are free from external magnetic fields and ferromagnets. Our findings present an interesting step towards high-efficiency spintronic devices. PMID:27546199

  2. Thermal emission spectra of Mars (5.4-10.5 microns) - Evidence for sulfates, carbonates, and hydrates

    NASA Technical Reports Server (NTRS)

    Pollack, James B.; Roush, Ted; Witteborn, Fred; Bregman, Jesse; Wooden, Diane; Stoker, Carol; Toon, Owen B.

    1990-01-01

    Spectra of the Martian thermal emission in the 5.4-10.5 micron region are reported. Emission features at 7.8 and 9.7 microns are attributed to surface silicates, and an emission feature at 6.1 micron is attributed to a molecular water component of the surface material. An absorption band at 8.7 micron and a possible one at 9.8 microns is attributed to sulfate or bisulfate anions probably located at a distorted crystalline site, and an absorption band at 6.7 microns is attributed to carbonate or bicarbonate anions located in a distorted crystalline site. Spectral simulations indicate that the sulfate- and carbonate-bearing minerals are contained in the same particles of airborne dust as the dominant silicate minerals, that the dust optical depth is about 0.6 at a reference wavelength of 0.3 micron over the area of the observed spots, and that sulfates and carbonates constitute 10-15 percent and 1-3 percent by volume of the airborne dust, respectively.

  3. Extrasolar Giant Magnetospheric Response to Steady-state Stellar Wind Pressure at 10, 5, 1, and 0.2 au

    NASA Astrophysics Data System (ADS)

    Tilley, Matt A.; Harnett, Erika M.; Winglee, Robert M.

    2016-08-01

    A three-dimensional, multifluid simulation of a giant planet’s magnetospheric interaction with steady-state stellar wind from a Sun-like star was performed for four different orbital semimajor axes—10, 5, 1, and 0.2 au. We simulate the effect of the increasing, steady-state stellar wind pressure related to the planetary orbital semimajor axis on the global magnetospheric dynamics for a Saturn-like planet, including an Enceladus-like plasma torus. Mass-loss processes are shown to vary with orbital distance, with the centrifugal interchange instability displayed only in the 10 and 5 au cases, which reach a state of mass-loss equilibrium more slowly than the 1 or 0.2 au cases. The compression of the magnetosphere in the 1 and 0.2 au cases contributes to the quenching of the interchange process by increasing the ratio of total plasma thermal energy to corotational energy. The strength of field-aligned currents, associated with auroral radio emissions, is shown to increase in magnitude and latitudinal coverage with a corresponding shift equatorward from increased dynamic ram pressure experienced in the hotter orbits. Similar to observed hot Jovian planets, the warm exo-Saturn simulated in the current work shows enhanced ion density in the magnetosheath and magnetopause regions, as well as the plasma torus, which could contribute to altered transit signals, suggesting that for planets in warmer (>0.1 au) orbits, planetary magnetic field strengths and possibly exomoons—via the plasma torus—could be observable with future missions.

  4. Extrasolar giant magnetospheric response to steady-state stellar wind pressure at 10, 5, 1, and 0.2 AU

    NASA Astrophysics Data System (ADS)

    Tilley, Matt; Harnett, Erika; Winglee, Robert

    2016-10-01

    A three-dimensional, multifluid simulation of a giant planet's magnetospheric interaction with steady-state stellar wind from a Sun-like star was performed for four different orbital semi-major axes - 10, 5, 1 and 0.2 AU. We simulate the effect of the increasing, steady-state stellar wind pressure related to the planetary orbital semi-major axis on the global magnetospheric dynamics for a Saturn-like planet, including an Enceladus-like plasma torus. Mass loss processes are shown to vary with orbital distance, with the centrifugal interchange instability displayed only in the 10 AU and 5 AU cases which reach a state of mass loss equilibrium more slowly than the 1 AU or 0.2 AU cases. The compression of the magnetosphere in the 1 AU and 0.2 AU cases contributes to the quenching of the interchange process by increasing the ratio of total plasma thermal energy to corotational energy. The strength of field-aligned currents (FAC), associated with auroral radio emissions, are shown to increase in magnitude and latitudinal coverage with a corresponding shift equatorward from increased dynamic ram pressure experienced in the hotter orbits. Similar to observed hot Jovian planets, the warm exo-Saturn simulated in the current work shows enhanced ion density in the magnetosheath and magnetopause regions, as well as the plasma torus which could contribute to altered transit signals, suggesting that for planets in warmer (> 0.1 AU) orbits, planetary magnetic field strengths and possibly exomoons - via the plasma torus - could be observable with future missions.

  5. Anomalies of The Moon's Thermal Emission In The Ir Spectral Range (10,5-12,5 Micron).

    NASA Astrophysics Data System (ADS)

    Pugacheva, S. G.; Shevchenko, V. V.

    New satellite measurements of the lunar surface radiation temperature were used to construct the spatial angular function of thermal radiation of the Moon in the infrared (10.5-12.5micron) spectral range. The basic material for investigations is the scanned cosmic spectrozonal images of the lunar surface transmitted by the first Russian geo- stationary artificial meteorological satellite "GOMS". In this paper I describe an ana- lytic model for the lunar thermal field, which is realized as an angular function of the thermal infrared radiation emitted by the lunar surface and analyse thermal anomalies of the lunar surface.A comparison of the regression dependence with radiation tem- peratures measured at some points of the lunar surface shows a systematic departure of the measured values from the average values. These deviations, depending on the surface albedo, characterize the photometric inhomogeneity of the lunar surface layer. On the lunar surface four groups of thermal anomalies are chosen: the thermal anoma- lies at the expense of different heat conduction of the lunar ground, thermal anomalies on the edge of the Moon's limb, "hot spots" - sites of the surface, which area are less than the sanction of the detector, anomalies stipulated by the relief of the surface. On detail study of large-scale photographs some anomalies are identified with small-sized craters, others with separate clusters of stones. The difference in temperature of the surface of the thermal anomalies can exceed 20 deg. The differences of temperature of the lunar surface layer indicate the extremely low heat conduction and high porosity of the material. Major factors of the photometric inhomogeneity are strong irregularities of the relief and the varied heat conduction of the lunar ground. The thermal anomalies for highland regions and for mare regions are shown in figure.

  6. Synthesis of CeFe10.5Mo1.5 with ThMn12-type structure by melt spinning

    SciTech Connect

    Zhou, C; Tessema, M; Meyer, MS; Pinkerton, FE

    2013-06-01

    Rare earth compounds RFe12_xMx with tetragonal ThMn12-type structure are of great research interest for potential applications as permanent magnets. These materials are known to serve as the precursors for nitriding and hydriding processes which in certain conditions can dramatically increase the Curie temperature, spontaneous magnetization, and affect the magnetic anisotropy. In this paper, we report the phase study of CeFe10.5Mo1.5 samples melt spun at various surface wheel speeds vs between 5 m/s and 60 m/s. The results from quantitative Rietveld analysis indicate that the as-spun ribbons are a mixture of primary CeFe10.5Mo1.5 phase with impurity phases such as Ce2Fe17, Fe-Mo alloy and CeFe2. When the wheel speed vs is below 25 m/s, CeFe10.5Mo1.5 phase accounts for greater than 85 wt% in the as-spun ribbons, while the Fe-Mo alloy is the only detectable impurity phase. Above v(s)=25 m/s, as the wheel speed increases, CeFe10.5Mo1.5 phase decreases monotonically to about 60 wt% at v(s)=6O m/s while the amounts of impurity phases increase. Thermogravimetric measurement indicates that the Curie temperature T-c. corresponding to CeFe10.5Mo1.5 phase is 341 K. As a result, the best performing sample melt spun at v(s),=15 m/s only exhibits an energy product BHmax=0.121 MGOe at room temperature. Although such a number is modest for a permanent magnet, further nitriding is expected to greatly enhance the Curie temperature, and hence the magnetic performance. (C) 2013 Elsevier B.V. All rights reserved.

  7. Deposition of calcium phosphate coatings using condensed phosphates (P2O7(4-) and P3O10(5-)) as phosphate source through induction heating.

    PubMed

    Zhou, Huan; Hou, Saisai; Zhang, Mingjie; Yang, Mengmeng; Deng, Linhong; Xiong, Xinbo; Ni, Xinye

    2016-12-01

    In present work condensed phosphates (P2O7(4-) and P3O10(5-)) were used as phosphate source in induction heating to deposit calcium phosphate coatings. The phase, morphology, and composition of different phosphate-related coatings were characterized and compared using XRD, FTIR, and SEM analyses. Results showed that P2O7(4-)formed calcium pyrophosphate hydrate coatings with interconnected cuboid-like particles. The as-deposited calcium tripolyphosphate hydrate coating with P3O10(5-) was mainly composed of flower-like particles assembled by plate-like crystals. The bioactivity and cytocompatibility of the coatings were also studied. Moreover, the feasibility of using hybrid phosphate sources for preparing and depositing coatings onto magnesium alloy was investigated. PMID:27612721

  8. Synthesis and structure of a new halophosphate Sr3P3O10Cl with the flexible [P3O10]5- anions

    NASA Astrophysics Data System (ADS)

    Gao, Jianhua; Liu, Xi; Song, Limei; Sha, Xunshan; Zhao, Pan; Guo, Ping

    2016-05-01

    A new halophosphate crystal Sr3P3O10Cl was grown in molten chloride flux media. It crystallizes in the centrosymmetric orthorhombic space group Pnma (No. 62) with a = 10.617(2) Å, b = 10.736(2) Å, and c = 8.7354(17) Å. In the structure, the basic building unit is the [P3O10]5- anion, which is consist of three PO4 tetrahedra by sharing the corner oxygen atoms. The two Sr atoms and the Cl atom are linked to construct an infinite [Sr3Cl]5+ chain. The [P3O10]5- anions are interconnected with the [Sr3Cl]5+ chains to form a three-dimensional frameworks. Additionally, the first-principle calculation was employed to obtain the band structures and densities of states.

  9. Milliwatt-level mid-infrared (10.5-16.5 μm) difference frequency generation with a femtosecond dual-signal-wavelength optical parametric oscillator.

    PubMed

    Hegenbarth, Robin; Steinmann, Andy; Sarkisov, Sergey; Giessen, Harald

    2012-09-01

    We demonstrate the generation of mid-infrared radiation using a femtosecond dual-signal-wavelength optical parametric oscillator and difference frequency generation in an extracavity gallium selenide or silver gallium diselenide crystal. This system generates up to 4.3 mW of average mid-infrared power. Its spectra can be tuned to between 10.5 μm and 16.5 μm wavelength (952  cm(-1)-606  cm(-1)) with more than 50  cm(-1) spectral bandwidth. We demonstrate that the power and spectra of this system are temporally very stable.

  10. A null c-myc mutation causes lethality before 10.5 days of gestation in homozygotes and reduced fertility in heterozygous female mice.

    PubMed

    Davis, A C; Wims, M; Spotts, G D; Hann, S R; Bradley, A

    1993-04-01

    To directly assess c-myc function in cellular proliferation, differentiation, and embryogenesis, we have used homologous recombination in embryonic stem cells to generate both heterozygous and homozygous c-myc mutant ES cell lines. The mutation is a null allele at the protein level. Mouse chimeras from seven heterozygous cell lines transmitted the mutant allele to their offspring. The analysis of embryos from two clones has shown that the mutation is lethal in homozygotes between 9.5 and 10.5 days of gestation. The embryos are generally smaller and retarded in development compared with their littermates. Pathologic abnormalities include the heart, pericardium, neural tube, and delay or failure in turning of the embryo. Heterozygous females have reduced fertility owing to embryonic resorption before 9.5 days of gestation in 14% of implanted embryos. c-Myc protein is necessary for embryonic survival beyond 10.5 days of gestation; however, it appears to be dispensable for cell division both in ES cell lines and in the embryo before that time.

  11. Research on fast fault identification method of 10.5 kV/1.5 kA superconducting fault current limiter

    NASA Astrophysics Data System (ADS)

    Zhang, Zhifeng; Sun, Qiang; Xiao, Liye; Liu, Daqian; Qiu, Ming; Qiu, Qinquan; Zhang, Guomin; Dai, Shaotao; Lin, Liangzhen

    2014-09-01

    Superconducting fault current limiter (SFCL) is a prospective electric devices connected in series in power grid to limit short-circuit current. A 10.5 kV/1.5 kA 3-phase SFCL with HTS coil of 6.24 mH was developed at IEECAS in China in 2005, which was operated in a local power grid in Hunan province for more than 11,000 h, and integrated lately in a superconducting power substation in Baiyin city in 2011 and is still running safely and reliably. In order to reduce the fault response time and enhance the performance of the SFCL, we analyzed the structure characteristics of the SFCL and discussed the variation of currents and voltages of the HTS coil and the bridge during the fault time. The simulation and tests results of power system validate the feasibility of the fast fault identification method.

  12. Effect of ball milling and thermal treatment on exchange bias and magnetocaloric properties of Ni48Mn39.5Sn10.5Al2 ribbons

    NASA Astrophysics Data System (ADS)

    Czaja, P.; Przewoźnik, J.; Fitta, M.; Bałanda, M.; Chrobak, A.; Kania, B.; Zackiewicz, P.; Wójcik, A.; Szlezynger, M.; Maziarz, W.

    2016-03-01

    The combined effect of ball milling and subsequent heat treatment on microstructure, magnetic, magnetocaloric and exchange bias properties of Ni48Mn39.5Sn10.5Al2 ribbons is reported. The annealing treatment results in the increase of the critical martensitic transformation temperature. The magnetic entropy change ΔSM of the order of 7.9 and -2.3 J kg K-1 for the annealed 50-32 μm powder fraction is determined. This is less than in the as melt spun ribbon but appears at a considerably higher temperature. At the same time EB is decreased due to annealing treatment. This decrease is attributed to the strengthened ferromagnetic exchange coupling due heat induced stress and structural relaxation.

  13. Coupled anion and cation ordering in Sr{sub 3}RFe{sub 4}O{sub 10.5} (R=Y, Ho, Dy) anion-deficientperovskites

    SciTech Connect

    Abakumov, Artem M.; D'Hondt, Hans; Rossell, Marta D.; Tsirlin, Alexander A.; Gutnikova, Olga; Filimonov, Dmitry S.; Schnelle, Walter; Rosner, Helge; Hadermann, Joke; Van Tendeloo, Gustaaf; Antipov, Evgeny V.

    2010-12-15

    The Sr{sub 3}RFe{sub 4}O{sub 10.5} (R=Y, Ho, Dy) anion-deficient perovskites were prepared using a solid-state reaction in evacuated sealed silica tubes. Transmission electron microscopy and {sup 57}Fe Moessbauer spectroscopy evidenced a complete A-cations and oxygen vacancies ordering. The structure model was further refined by ab initio structure relaxation, based on density functional theory calculations. The compounds crystallize in a tetragonal a{approx}2{radical}2a{sub p{approx}}11.3 A, c{approx}4c{sub p{approx}}16 A unit cell (a{sub p}: parameter of the perovskite subcell) with the P4{sub 2}/mnm space group. Oxygen vacancies reside in the (FeO{sub 5/4{open_square}3/4}) layers, comprising corner-sharing FeO{sub 4} tetrahedra and FeO{sub 5} tetragonal pyramids, which are sandwiched between the layers of the FeO{sub 6} octahedra. Smaller R atoms occupy the 9-fold coordinated position, whereas the 10-fold coordinated positions are occupied by larger Sr atoms. The Fe sublattice is ordered aniferromagnetically up to at least 500 K, while the rare-earth sublattice remains disordered down to 2 K. -- Graphical abstract: The Sr{sub 3}RFe{sub 4}O{sub 10.5} (R=Y, Ho, Dy) anion-deficient perovskites with a complete ordering of the A-cations and oxygen vacancies have been prepared using a solid-state reaction in evacuated sealed silica tubes. Oxygen vacancies reside in the (FeO{sub 5/43/4}) layers, comprising corner-sharing FeO{sub 4} tetrahedra and FeO{sub 5} tetragonal pyramids, which are sandwiched between the layers of the FeO{sub 6} octahedra. Smaller R atoms occupy the 9-fold coordinated position, whereas the 10-fold coordinated positions are occupied by larger Sr atoms.

  14. Evolution and CNO yields of Z = 10-5 stars and possible effects on carbon-enhanced metal-poor production

    NASA Astrophysics Data System (ADS)

    Gil-Pons, P.; Doherty, C. L.; Lau, H.; Campbell, S. W.; Suda, T.; Guilani, S.; Gutiérrez, J.; Lattanzio, J. C.

    2013-09-01

    Aims: Our main goals are to get a deeper insight into the evolution and final fates of intermediate-mass, extremely metal-poor (EMP) stars. We also aim to investigate the C, N, and O yields of these stars. Methods: Using the Monash University Stellar Evolution code MONSTAR we computed and analysed the evolution of stars of metallicity Z = 10-5 and masses between 4 and 9 M⊙, from their main sequence until the late thermally pulsing (super) asymptotic giant branch, TP-(S)AGB phase. Results: Our model stars experience a strong C, N, and O envelope enrichment either due to the second dredge-up process, the dredge-out phenomenon, or the third dredge-up early during the TP-(S)AGB phase. Their late evolution is therefore similar to that of higher metallicity objects. When using a standard prescription for the mass loss rates during the TP-(S)AGB phase, the computed stars are able to lose most of their envelopes before their cores reach the Chandrasekhar mass (mCh), so our standard models do not predict the occurrence of SNI1/2 for Z = 10-5 stars. However, we find that the reduction of only one order of magnitude in the mass-loss rates, which are particularly uncertain at this metallicity, would prevent the complete ejection of the envelope, allowing the stars to either explode as an SNI1/2 or become an electron-capture SN. Our calculations stop due to an instability near the base of the convective envelope that hampers further convergence and leaves remnant envelope masses between 0.25 M⊙ for our 4 M⊙ model and 1.5 M⊙ for our 9 M⊙ model. We present two sets of C, N, and O yields derived from our full calculations and computed under two different assumptions, namely, that the instability causes a practically instant loss of the remnant envelope or that the stars recover and proceed with further thermal pulses. Conclusions: Our results have implications for the early chemical evolution of the Universe and might provide another piece for the puzzle of the carbon

  15. Wide-band (2.5 - 10.5 µm), high-frame rate IRFPAs based on high-operability MCT on silicon

    NASA Astrophysics Data System (ADS)

    Crosbie, Michael J.; Giess, Jean; Gordon, Neil T.; Hall, David J.; Hails, Janet E.; Lees, David J.; Little, Christopher J.; Phillips, Tim S.

    2010-04-01

    We have previously presented results from our mercury cadmium telluride (MCT, Hg1-xCdxTe) growth on silicon substrate technology for different applications, including negative luminescence, long waveband and mid/long dual waveband infrared imaging. In this paper, we review recent developments in QinetiQ's combined molecular beam epitaxy (MBE) and metal-organic vapor phase epitaxy (MOVPE) MCT growth on silicon; including MCT defect density, uniformity and reproducibility. We also present a new small-format (128 x 128) focal plane array (FPA) for high frame-rate applications. A custom high-speed readout integrated circuit (ROIC) was developed with a large pitch and large charge storage aimed at producing a very high performance FPA (NETD ~10mK) operating at frame rates up to 2kHz for the full array. The array design allows random addressing and this allows the maximum frame rate to be increased as the window size is reduced. A broadband (2.5-10.5 μm) MCT heterostructure was designed and grown by the MBE/MOVPE technique onto silicon substrates. FPAs were fabricated using our standard techniques; wet-etched mesa diodes passivated with epitaxial CdTe and flip-chip bonded to the ROIC. The resulting focal plane arrays were characterized at the maximum frame rate and shown to have the high operabilities and low NETD values characteristic of our LWIR MCT on silicon technology.

  16. Externally applied electric fields up to 1.6 × 10(5) V/m do not affect the homogeneous nucleation of ice in supercooled water.

    PubMed

    Stan, Claudiu A; Tang, Sindy K Y; Bishop, Kyle J M; Whitesides, George M

    2011-02-10

    The freezing of water can initiate at electrically conducting electrodes kept at a high electric potential or at charged electrically insulating surfaces. The microscopic mechanisms of these phenomena are unknown, but they must involve interactions between water molecules and electric fields. This paper investigates the effect of uniform electric fields on the homogeneous nucleation of ice in supercooled water. Electric fields were applied across drops of water immersed in a perfluorinated liquid using a parallel-plate capacitor; the drops traveled in a microchannel and were supercooled until they froze due to the homogeneous nucleation of ice. The distribution of freezing temperatures of drops depended on the rate of nucleation of ice, and the sensitivity of measurements allowed detection of changes by a factor of 1.5 in the rate of nucleation. Sinusoidal alternation of the electric field at frequencies from 3 to 100 kHz prevented free ions present in water from screening the electric field in the bulk of drops. Uniform electric fields in water with amplitudes up to (1.6 ± 0.4) × 10(5) V/m neither enhanced nor suppressed the homogeneous nucleation of ice. Estimations based on thermodynamic models suggest that fields in the range of 10(7)-10(8) V/m might cause an observable increase in the rate of nucleation.

  17. A New Niobium Cluster Oxychloride Built from Interconnected Nb 6Cl 12O 6 Units: Na 0.21Nb 6Cl 10.5O 3

    NASA Astrophysics Data System (ADS)

    Gulo, Fakhili; Perrin, Christiane

    2002-01-01

    The new Na0.21Nb6Cl10.5O3 oxychloride was synthesized by a solid state route, from NaCl, Nb2O5, NbCl5, and Nb, heated at 680°C for 2 weeks. The structure was determined by single-crystal X-ray diffraction. It crystallizes in the trigonal system (Roverline3c space group, a=11.5048(1) Å, c=44.9446(7) Å, V=5151.88(10) Å3, Z=12). The structure is built from [(Nb6Cli9Oi3) Oa3Cla3] units, which share their inner and apical oxygens forming pseudolayers with short Nb-Nb intercluster distances (3.399 Å). Along the c axis, these layers are interconnected by apical-apical chlorines. The sodium atoms are randomly distributed in the voids arranged between two adjacent layers, in a deformed chlorine prismatic coordination. The developed formula Na0.21 [(Nb6Cli9Oi-a3/2)Oa-i3/2Cla-a3/2] leads to a number of valence electrons per cluster close to 14. This oxychloride will be compared to CsNb6Cl12O2 which we have previously isolated and which was the first example of a Nb6 oxyhalide involving Oi-a, Oa-i interunit connections.

  18. Molecular simulation of fluids with non-identical intermolecular potentials: Thermodynamic properties of 10-5 + 12-6 Mie potential binary mixtures

    SciTech Connect

    Stiegler, Thomas; Sadus, Richard J.

    2015-02-28

    General methods for combining interactions between particles characterised by non-identical intermolecular potentials are investigated. The combination methods are tested by performing molecular dynamics simulations to determine the pressure, energy, isochoric and isobaric heat capacities, thermal expansion coefficient, isothermal compressibility, Joule-Thomson coefficient, and speed of sound of 10-5 + 12-6 Mie potential binary mixtures. In addition to the two non-identical Mie potentials, mixtures are also studied with non-identical intermolecular parameters. The combination methods are compared with results obtained by simply averaging the Mie exponents. When either the energy or size parameters are non-identical, very significant differences emerge in the thermodynamic properties predicted by the alternative combination methods. The isobaric heat capacity is the thermodynamic property that is most affected by the relative magnitude of the intermolecular potential parameters and the method for combining non-identical potentials. Either the arithmetic or geometric combination of potentials provides a simple and effective way of performing simulations involving mixtures of components characterised by non-identical intermolecular potentials, which is independent of their functional form.

  19. Molecular simulation of fluids with non-identical intermolecular potentials: Thermodynamic properties of 10-5 + 12-6 Mie potential binary mixtures

    NASA Astrophysics Data System (ADS)

    Stiegler, Thomas; Sadus, Richard J.

    2015-02-01

    General methods for combining interactions between particles characterised by non-identical intermolecular potentials are investigated. The combination methods are tested by performing molecular dynamics simulations to determine the pressure, energy, isochoric and isobaric heat capacities, thermal expansion coefficient, isothermal compressibility, Joule-Thomson coefficient, and speed of sound of 10-5 + 12-6 Mie potential binary mixtures. In addition to the two non-identical Mie potentials, mixtures are also studied with non-identical intermolecular parameters. The combination methods are compared with results obtained by simply averaging the Mie exponents. When either the energy or size parameters are non-identical, very significant differences emerge in the thermodynamic properties predicted by the alternative combination methods. The isobaric heat capacity is the thermodynamic property that is most affected by the relative magnitude of the intermolecular potential parameters and the method for combining non-identical potentials. Either the arithmetic or geometric combination of potentials provides a simple and effective way of performing simulations involving mixtures of components characterised by non-identical intermolecular potentials, which is independent of their functional form.

  20. The physical properties of the HH 30 jet from HST and ground-based data

    NASA Astrophysics Data System (ADS)

    Bacciotti, Francesca; Eislöffel, Jochen; Ray, Thomas P.

    1999-10-01

    the same positions, although we cannot exclude the presence of small-scale variations, because of the lower spatial resolution with which these quantities have been derived. Alternatively, the lack of large density enhancements at the locations corresponding to the knots may be due to the presence of a substantial magnetic field in the body of the jet. Anyway, the absence of evident bow-shaped features suggests that in this jet it is more likely that the chain of bright spots traces travelling plasma instabilities, rather than a series of internal working surfaces. Along the jet the mass-loss rate is quite moderate: assuming an average flow speed of 200 km s(-1) , and adopting as our jet diameter the emission-weighted jet width, we find dot {M} ~ 1.7 10(-9) Msun yr(-1) and correspondingly dot {P} ~ 3.5 10(-7) Msun yr(-1) km s(-1) . In the counter-jet, in contrast, dot {M} (dot {P}) decreases from about 1.8 10(-9) Msun yr(-1) (3.6 10(-7) Msun yr(-1) km s(-1) ) at 0.6" from the source to about 9.3 10(-10) Msun yr(-1) (1.9 10(-7) Msun yr(-1) km s(-1) ) further out.

  1. π-Electron ring-currents and bond-currents in [10,5]-Coronene and related structures conforming to the 'Annulene-Within-an-Annulene' model.

    PubMed

    Dickens, T K; Mallion, R B

    2013-06-01

    A series of hypothetical conjugated structures is defined; the series is called the p-Coronenes and the first four members of it are shown to respect the 'Annulene-Within-an-Annulene' (AWA) model when tested by means of Hückel-London-Pople-McWeeny (HLPM) π-electron ring-current and bond-current calculations. The first member of this series, 5-Coronene, is also a member of the regular [r,s]-Coronene series, where it is known as [10,5]-Coronene. It is shown that, as p is varied (with p always odd, and with p > 3) through the values 5, 7, 9, 11, etc., the resulting structures alternate between a '[4n + 2]-Annulene-Within-a-[4m]-Annulene' (if (p- 1) is divisible by 4) and a '[4n]-Annulene-Within-a-[4m + 2]-Annulene' (if (p- 1) is not divisible by 4). It is therefore claimed that the p-Coronenes constitute an ideal series for testing the AWA model. It is also remarked that each member of the p-Coronene series has only four Kekulé structures, and that the 'spokes' or 'transverse' bonds connecting the central [p(p- 3)]-membered ring to the outer [p(p- 1)]-membered periphery always have a Pauling bond-order of zero, ensuring that the outer and inner rings are 'decoupled'; such bonds also bear zero bond-current, by symmetry. It is argued that the former property of these transverse bonds, rather than the latter, determines that the p-Coronenes obey the AWA rule-which is in fact an exception, rather than a 'rule'per se. The paper concludes by explicitly stating our philosophy that a conceptually simple model depending on no subjective (or any other) parameters whatsoever can give intuitive chemical insight for certain systems equal to that available from far-more complex methods such as ab initio calculations-what Coulson once famously called 'primitive patterns of understanding'.

  2. Facile construction of pyrrolo[1,2-b]isoquinolin-10(5H)-ones via a redox-amination-aromatization-Friedel-Crafts acylation cascade reaction and discovery of novel topoisomerase inhibitors.

    PubMed

    Wu, Shanchao; Liu, Na; Dong, Guoqiang; Ma, Lin; Wang, Shengzheng; Shi, Wencai; Fang, Kun; Chen, Shuqiang; Li, Jian; Zhang, Wannian; Sheng, Chunquan; Wang, Wei

    2016-07-21

    An efficient redox-amination-aromatization-Friedel-Crafts acylation cascade process from trans-4-hydroxyproline and 2-formylbenzoic acids has been developed for the synthesis of pyrrolo[1,2-b]isoquinolin-10(5H)-ones. Compound 3h was identified as a new potent dual topoisomerase I/II inhibitor. PMID:27400278

  3. 46 CFR 56.10-5 - Pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... design limits of stress and temperature indicated in ASME B31.1 (incorporated by reference; see 46 CFR 56...-22 of this chapter.) (c) Nonferrous pipe. (See also § 56.60-20.) (1) Copper and brass pipe for water... temperatures to 406 °F. (2) Copper and brass pipe for air may be used in accordance with the allowable...

  4. 43 CFR 10.5 - Consultation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... REPATRIATION REGULATIONS Human Remains, Funerary Objects, Sacred Objects, or Objects of Cultural Patrimony From... inadvertent discovery of human remains, funerary objects, sacred objects, or objects of cultural patrimony on... likely to be, culturally affiliated with the human remains, funerary objects, sacred objects, or......

  5. 49 CFR 10.5 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... its own Privacy Act regulations (49 CFR Part 1007), except to the extent that any system of records... Corporation. (8) Pipeline and Hazardous Materials Safety Administration. (9) Research and Innovative... or an alien lawfully admitted; Maintain includes maintain, collect, use, or disseminate; May is...

  6. 49 CFR 10.5 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... its own Privacy Act regulations (49 CFR Part 1007), except to the extent that any system of records... Corporation. (8) Pipeline and Hazardous Materials Safety Administration. (9) Research and Innovative... or an alien lawfully admitted; Maintain includes maintain, collect, use, or disseminate; May is...

  7. 49 CFR 10.5 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... its own Privacy Act regulations (49 CFR Part 1007), except to the extent that any system of records... Corporation. (8) Pipeline and Hazardous Materials Safety Administration. (9) Research and Innovative... or an alien lawfully admitted; Maintain includes maintain, collect, use, or disseminate; May is...

  8. 49 CFR 10.5 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... its own Privacy Act regulations (49 CFR Part 1007), except to the extent that any system of records... Corporation. (8) Pipeline and Hazardous Materials Safety Administration. (9) Research and Innovative... or an alien lawfully admitted; Maintain includes maintain, collect, use, or disseminate; May is...

  9. 49 CFR 10.5 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Department. Includes means “includes but is not limited to;” Individual means a citizen of the United States... determination about an identifiable individual, except as provided by section 8 of title 13, United States Code... its own Privacy Act regulations (49 CFR Part 1007), except to the extent that any system of...

  10. 32 CFR 10.5 - Construction.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Certain Non-Citizens in the War Against Terrorism.” Nothing in these Military Commission Instructions..., “Detention, Treatment, and Trial of Certain Non-Citizens in the War Against Terrorism,” shall govern as... Certain Non-Citizens in the War Against Terrorism.” Pronouns referring to the male gender shall...

  11. 46 CFR 56.10-5 - Pipe.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... found from Table 56.60-1(a). (3) Copper-nickel alloys may be used for water and steam service within the design limits of stress and temperature indicated in ASME B31.1 (incorporated by reference; see 46 CFR 56... specifically permitted by this part. (6) Aluminum-alloy pipe or tube along with similar junction equipment...

  12. 46 CFR 56.10-5 - Pipe.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... found from table 56.60-1(a). (3) Copper-nickel alloys may be used for water and steam service within the design limits of stress and temperature indicated in ASME B31.1 (incorporated by reference; see 46 CFR 56... specifically permitted by this part. (6) Aluminum-alloy pipe or tube along with similar junction equipment...

  13. 46 CFR 2.10-5 - Exemptions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...: (1) Training youth in boating, seamanship, or navigation skills; (2) Educating youth in a course of marine environmental studies; (3) Providing excursions for persons with disabilities as defined under...

  14. 46 CFR 2.10-5 - Exemptions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...: (1) Training youth in boating, seamanship, or navigation skills; (2) Educating youth in a course of marine environmental studies; (3) Providing excursions for persons with disabilities as defined under...

  15. 32 CFR 10.5 - Construction.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... with 32 CFR part 9, and Military Order of November 13, 2001, “Detention, Treatment, and Trial of... event of an inconsistency, the provisions of 32 CFR part 9, and Military Order of November 13, 2001... Certain Non-Citizens in the War Against Terrorism.” Pronouns referring to the male gender shall...

  16. 32 CFR 10.5 - Construction.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... with 32 CFR part 9, and Military Order of November 13, 2001, “Detention, Treatment, and Trial of... event of an inconsistency, the provisions of 32 CFR part 9, and Military Order of November 13, 2001... Certain Non-Citizens in the War Against Terrorism.” Pronouns referring to the male gender shall...

  17. Poly[[dodeca­aqua­bis­(μ3-pyridine-2,6-dicarboxyl­ato)tetra­kis­(μ2-pyridine-2,6-dicarboxyl­ato)tri­calciumdieuropium(III)] 10.5-hydrate

    PubMed Central

    Shi, Fengjuan; Deng, Jiguang; Dai, Hongxing

    2012-01-01

    In the title compound, {[Ca3Eu2(C7H3NO4)6(H2O)12]·10.5H2O}n, the EuIII ion is nine-coordinated by three tridentate pyridine-2,6-dicarboxyl­ate (PDA) ligands, forming a [Eu(PDA)3]3− building block. The Ca2+ ions adopt two types of coordination geometries. One Ca2+ ion, lying on a twofold rotation axis, is eight-coordinated by four carboxyl­ate O atoms from four PDA ligands and four water mol­ecules, and the other two Ca2+ ions, each lying on an inversion center, are six-coordinated by two carboxyl­ate O atoms from two PDA ligands and four water mol­ecules. The carboxyl­ate groups bridge the EuIII and Ca2+ ions into a three-dimensional porous framework, with channels extending along [010] and [001] in which lattice water mol­ecules are located. Two of the lattice water mol­ecules are disordered over two sets of sites with equal occupancy and one water mol­ecule is 0.25-occupied. Numerous O—H⋯O hydrogen bonds involving the water mol­ecules and carboxyl­ate O atoms are present. PMID:22590167

  18. Structural and relaxor-like dielectric properties of unfilled tungsten bronzes Ba5-5xSm5xTi5xNb10-5xO30

    NASA Astrophysics Data System (ADS)

    Wei, T.; Dong, Z.; Zhao, C. Z.; Guo, Y. Y.; Zhou, Q. J.; Li, Z. P.

    2016-03-01

    New unfilled tetragonal tungsten bronze (TTB) oxides, Ba5-5xSm5xTi5xNb10-5xO30 (BSTN-x), where 0.10 ≤ x ≤ 0.35, have been synthesized in this work. Their crystal structure was determined and analyzed based on Rietveld structural refinement. It is found that single TTB phase can be formed in a particular x range (i.e., 0.15 ≤ x ≤ 0.3) due to the competition interaction between tolerance factor and electronegativity difference. Furthermore, dielectric and ferroelectric results indicate that phase transitions and ferroelectric states are sensitive to x. Referring to the local chemistry, we suggest that the raise of vacancies at the A2-site compared with that of A1-site will intensely depress the normal ferroelectric phase and is in favor of relaxor ferroelectric state. Macroscopically, previous A-site size difference standpoint on fill TTB compounds cannot give a reasonable explanation about the variation of dielectric maximum temperature (Tm) for present BSTN-x compounds. Alternatively, tetragonality (c/a) is adopted which can well describe the variation of Tm in whole x range. In addition, one by one correspondence between tetragonality and electrical features can be found, and the compositions involving high c/a are usually stabilized in normal ferroelectric phase. It is believed that c/a is a more appropriate parameter to illustrate the variation of ferroelectric properties for unfilled TTB system.

  19. L-shell X-ray production cross sections of Ce, Nd, Sm, Eu, Gd, and Dy by impact of 14N2+ ions with energies between 7.0 MeV and 10.5 MeV

    NASA Astrophysics Data System (ADS)

    Murillo, G.; Méndez, B.; López-Monroy, J.; Miranda, J.; Villaseñor, P.

    2016-09-01

    L-shell X-ray production cross sections from the lanthanoid elements Ce, Nd, Sm, Eu, Gd, and Dy, induced by the impact of 14N2+ ions with energies in the interval 7.0 MeV to 10.5 MeV (0.50 MeV/μ to 0.75 MeV/μ), were measured and then compared with theoretical calculations obtained with the ECPSSR model with exact limits of integration (eCPSSR) and related corrections. These include the electron capture by the incoming ion and multiple ionizations of higher shells. Data from this work were contrasted with previously published L X-ray production cross sections for 14N2+ ion impact. As with other ions, a universal behavior is found when Lα and Lγ X-ray production cross sections are plotted as a function of reduced velocity parameters. The agreement with theoretical predictions was very good when the corrections were applied to the eCPSSR model.

  20. The structure of the jovian magnetopause boundary layer of energetic ions and electrons and its implications on 10 / 5 hour periodicities: ulysses, voyager 1 and 2, and pioneer 11 observations

    NASA Astrophysics Data System (ADS)

    Anagnostopoulos, G. C.; Karanikola, I. N.; Marhavilas, P.; Sarris, E. T.; Balogh, A.

    A large scale magnetopause boundary layer (MPBL) of energetic ions and electrons has been strongly suggested by the analysis of observations from different instruments (HISCALE, EPAC, COSPIN) onboard Ulysses, during its flyby of Jupiter (Cowley et al., 1996; Anagnostopoulos et al., 1998, 2001; Krupp et al., 1999). The Hiscale observations suggest a MPBL that is more evident at higher latitudes and extends all the way from ˜ 49 to ˜ 83 RJ in the south duskside magnetosphere. The energetic particle and relativistic electron observations suggest energy dependent intensity gradients within the MPBL. The intensities increase, the spectra harden and the pitch angle distribution become more anisotropic along the magnetic field lines with increasing distance from the magnetopause. As a consequence of the structure of the MPBL and of the ˜ 10 hour rotation of the Jovian magnetosphere, ˜ 10 / 5 hour variations in the spectrum and the PADs were observed at high latitudes. A major and probably the principal source of the MPBL was found to be a quasi-periodic (15-80 min) particle emission from near the planet at high latitudes, in phase with magnetospheric pulsations. Evidence of a large scale MPBL of energetic particles and relativistic electrons was also found in Voyager 1 and 2 and Pioneer 10 and 11 observations and suggests that the MPBL is a major particle region in the Jovian magnetosphere and a possible source of the inner magnetosphere.

  1. Inoculum effects of ceftobiprole, daptomycin, linezolid, and vancomycin with Staphylococcus aureus and Streptococcus pneumoniae at inocula of 10(5) and 10(7) CFU injected into opposite thighs of neutropenic mice.

    PubMed

    Lee, Dong-Gun; Murakami, Yoichi; Andes, David R; Craig, William A

    2013-03-01

    Reduced bactericidal efficacy at a high inoculum is known as the inoculum effect (IE). We used neutropenic mice to compare the IEs of ceftobiprole (CFB), daptomycin (DAP), linezolid (LZD), and vancomycin (VAN) against 6 to 9 strains of Staphylococcus aureus and 4 strains of Streptococcus pneumoniae at 2 inocula in opposite thighs of the same mice. Neutropenic mice had 10(4.5) to 10(5.7) CFU/thigh (low inoculum [LI]) in one thigh and 10(6.4) to 10(7.2) CFU/thigh (high inoculum [HI]) in the opposite thigh when treated for 24 h with subcutaneous (s.c.) doses every 12 h of DAP at 0.024 to 100 mg/kg of body weight and LZD at 0.313 to 320 mg/kg and s.c. doses every 6 h of CFB at 0.003 to 160 mg/kg and VAN at 0.049 to 800 mg/kg. Dose-response data were analyzed by a maximum effect (E(max)) model using nonlinear regression. Static doses for each drug and at each inoculum were calculated, and the difference between HI and LI (IE index) gave the magnitude of IE for each drug-organism combination. Mean (range) IE indexes of S. aureus were 2.9 (1.7 to 4.6) for CFB, 4.1 (2.6 to 9.3) for DAP, 4.6 (1.7 to 7.1) for LZD, and 10.1 (6.3 to 20.3) for VAN. In S. pneumoniae, the IE indexes were 2.5 (1.3 to 3.3) for CFB, 2.0 (1.6 to 2.8) for DAP, 1.9 (1.7 to 2.2) for LZD, and 1.5 (0.8 to 3.2) for VAN; these values were similar for all drugs. In S. aureus, the IE was much larger with VAN than with CFB, DAM, and LZD (P < 0.05). An in vivo time course of vancomycin activity showed initiation of killing at 4- to 16-fold-higher doses at HI than at LI despite similar initial growth of controls.

  2. VizieR Online Data Catalog: 4yr 1.3mm VLBI observations of SgrA* with EHT (Fish+, 2016)

    NASA Astrophysics Data System (ADS)

    Fish, V. L.; Johnson, M. D.; Doeleman, S. S.; Broderick, A. E.; Psaltis, D.; Lu, R.-S.; Akiyama, K.; Alef, W.; Algaba, J. C.; Asada, K.; Beaudoin, C.; Bertarini, A.; Blackburn, L.; Blundell, R.; Bower, G. C.; Brinkerink, C.; Cappallo, R.; Chael, A. A.; Chamberlin, R.; Chan, C.-K.; Crew, G. B.; Dexter, J.; Dexter, M.; Dzib, S. A.; Falcke, H.; Freund, R.; Friberg, P.; Greer, C. H.; Gurwell, M. A.; Ho, P. T. P.; Honma, M.; Inoue, M.; Johannsen, T.; Kim, J.; Krichbaum, T. P.; Lamb, J.; Leon-Tavares, J.; Loeb, A.; Loinard, L.; MacMahon, D.; Marrone, D. P.; Moran, J. M.; Moscibrodzka, M.; Ortiz-Leon, G. N.; Oyama, T.; Ozel, F.; Plambeck, R. L.; Pradel, N.; Primiani, R. A.; Rogers, A. E. E.; Rosenfeld, K.; Rottmann, H.; Roy, A. L.; Ruszczyk, C.; Smythe, D. L.; Soohoo, J.; Spilker, J.; Stone, J.; Strittmatter, P.; Tilanus, R. P. J.; Titus, M.; Vertatschitsch, L.; Wagner, J.; Wardle, J. F. C.; Weintroub, J.; Woody, D.; Wright, M.; Yamaguchi, P.; Young, A.; Young, K. H.; Zensus, J. A.; Ziurys, L. M.

    2016-06-01

    The Event Horizon Telescope (EHT) obtained detections of Sgr A* on closed triangles of baselines among stations in Arizona, California, and Hawaii in 2009, 2011, 2012, and 2013. In all cases, two 480MHz bands, centered at 229.089GHz and 229.601GHz (hereafter, low and high bands, respectively), were observed. One or more telescopes from each of three sites in Arizona, California, and Hawaii participated in each set of observations. The Arizona Radio Observatory (ARO) Submillimeter Telescope (SMT) on Mt. Graham, Arizona, was used in all cases. Over the years of data analyzed here, the configuration of VLBI recording at these sites evolved as described in section 2.1. (1 data file).

  3. Is it possible that a gravity increase of 20 μGal yr-1 in southern Tibet comes from a wide-range density increase?

    NASA Astrophysics Data System (ADS)

    Yi, Shuang; Wang, Qiuyu; Sun, Wenke

    2016-02-01

    With absolute gravimetric observations from 2010 to 2013 in the southern Tibet, Chen et al. (2016) reported a gravity increase of up to 20 μGal/yr and concluded that it is possible if there was a density increase in a disk range of 580 km in diameter. Here we used observations from the gravity satellites Gravity Recovery and Climate Experiment (GRACE) over 12 years to evaluate whether the model was practical, because a mass accumulation in such a large spatial range is well within the detectability ability of GRACE. The gravity trend based on their model is orders of magnitude larger than the GRACE observation, thus negating its conclusions. We then evaluated contributions from seasonal variation, lakes, glaciers, rivers, precipitation, and snowfall and concluded that these factors cannot cause such a large gravity signal. Finally, we discussed some possible explanations for the gravity increase of 40 μGal in two years.

  4. 46 CFR 193.10-5 - Fire main system, details.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...; or, (B) The bridge, if there is no fire control station; or, (C) A readily accessible space.... (b) On vessels of 1,000 gross tons and over on an international voyage, each required fire pump... in separate spaces, and the arrangement, pumps, sea connections, and sources of power must be such...

  5. 17 CFR 10.5 - Computation of time.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... computed is to be included unless it is a Saturday, a Sunday, or a legal holiday; in which event the period runs until the end of the next day which is not a Saturday, a Sunday or a legal holiday. Intermediate Saturdays, Sundays, and legal holidays shall be excluded from the computation only when the period of...

  6. 17 CFR 10.5 - Computation of time.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... computed is to be included unless it is a Saturday, a Sunday, or a legal holiday; in which event the period runs until the end of the next day which is not a Saturday, a Sunday or a legal holiday. Intermediate Saturdays, Sundays, and legal holidays shall be excluded from the computation only when the period of...

  7. 17 CFR 10.5 - Computation of time.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... computed is to be included unless it is a Saturday, a Sunday, or a legal holiday; in which event the period runs until the end of the next day which is not a Saturday, a Sunday or a legal holiday. Intermediate Saturdays, Sundays, and legal holidays shall be excluded from the computation only when the period of...

  8. 46 CFR 76.10-5 - Fire pumps.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... provided at least one of the required pumps is kept available for use on the fire system at all times. In... separate spaces and the arrangement of pumps, sea connections, and sources of power shall be such as to insure that a fire in any one space will not put all of the fire pumps out of operation. However,...

  9. 46 CFR 194.10-5 - Type and location.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... utilized shall not be used for stowage of other hazardous materials covered by 49 CFR parts 171-179. The... requirements of 49 CFR part 176. (c) Magazine chests. (1) Magazine chests shall be located on the weather decks... intended for the stowage of blasting caps, detonators, or boosters, in addition to the requirements in...

  10. 46 CFR 194.10-5 - Type and location.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... utilized shall not be used for stowage of other hazardous materials covered by 49 CFR parts 171-179. The... requirements of 49 CFR part 176. (c) Magazine chests. (1) Magazine chests shall be located on the weather decks... intended for the stowage of blasting caps, detonators, or boosters, in addition to the requirements in...

  11. 46 CFR 97.10-5 - Persons excluded.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., United States Navy, National Geospatial-Intelligence Agency, National Ocean Service, United States Army Corps of Engineers, Maritime Administration, and National Transportation Safety Board may be allowed in... navigation of the vessel. However, licensed officers of vessels, persons regularly engaged in...

  12. 46 CFR 58.10-5 - Gasoline engine installations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... permitted only if they do not pass through living or berthing spaces, they terminate above the deepest load... flame arrester complying with SAE J-1928 (incorporated by reference; see 46 CFR 58.03-1) or UL 1111 (incorporated by reference; see 46 CFR 58.03-1) and marked accordingly. The flame arrester must be...

  13. 46 CFR 58.10-5 - Gasoline engine installations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... permitted only if they do not pass through living or berthing spaces, they terminate above the deepest load... flame arrester complying with SAE J-1928 (incorporated by reference; see 46 CFR 58.03-1) or UL 1111 (incorporated by reference; see 46 CFR 58.03-1) and marked accordingly. The flame arrester must be...

  14. 46 CFR 58.10-5 - Gasoline engine installations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... permitted only if they do not pass through living or berthing spaces, they terminate above the deepest load... flame arrester complying with SAE J-1928 (incorporated by reference; see 46 CFR 58.03-1) or UL 1111 (incorporated by reference; see 46 CFR 58.03-1) and marked accordingly. The flame arrester must be...

  15. 46 CFR 58.10-5 - Gasoline engine installations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... permitted only if they do not pass through living or berthing spaces, they terminate above the deepest load... flame arrester complying with SAE J-1928 (incorporated by reference; see 46 CFR 58.03-1) or UL 1111 (incorporated by reference; see 46 CFR 58.03-1) and marked accordingly. The flame arrester must be...

  16. 46 CFR 193.10-5 - Fire pumps.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Minimum number of pumps Hose and hydrant size, inches Nozzle orifice size, inches Length of hose, feet 100... vessels of 65 feet in length or less, 3/4-inch hose of good commercial grade together with a commercial garden hose nozzle may be used. The pump may be hand operated and the length of hose shall be...

  17. 46 CFR 193.10-5 - Fire main system, details.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... of a total flooding system using carbon dioxide or a clean agent complying with 46 CFR subpart 95.16... tons Over Not over Minimum number of pumps Hose and hydrant size, inches Nozzle orifice size, inches Length of hose, feet 100 1 1 1 11/2 1 1/2 50 100 1,000 1 11/2 5/8 50 1,000 1,500 2 11/2 5/8 50 1,500 2...

  18. 46 CFR 76.10-5 - Fire pumps.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... with a pressure gauge on the discharge side of the pumps. (f) Fire pumps may be used for other purposes... capable of delivering water simultaneously from the two highest outlets at a Pitot tube pressure of... excess of the pressure necessary to maintain the requirements of paragraph (c) of this section or 125...

  19. Observation by two-photon laser spectroscopy of the 4d{sup 10}5s {sup 2}S{sub 1/2}{yields}4d{sup 9}5s{sup 2} {sup 2}D{sub 5/2} clock transition in atomic silver

    SciTech Connect

    Badr, T.; Plimmer, M. D.; Juncar, P.; Himbert, M. E.; Louyer, Y.; Knight, D. J. E.

    2006-12-15

    We report the observation of the very narrow 4d{sup 10}5s {sup 2}S{sub 1/2}{yields}4d{sup 9}5s{sup 2} {sup 2}D{sub 5/2} transition in atomic silver. The frequencies of the hyperfine components in {sup 107}Ag and {sup 109}Ag have been measured using Doppler-free two-photon laser spectroscopy of a thermal beam and heterodyne calibration with respect to the a{sub 1} component of the 62P(4-5) line in molecular iodine near 661 nm. For the center of gravity of a mixture of natural abundance, we deduce the value 906 641 295.77(19) MHz. For the isotope shift, we obtain {nu}({sup 109}Ag)-{nu}({sup 107}Ag)=564.15(37) MHz, from which we deduce the frequency and isotope shift of the 4d{sup 10}5s {sup 2}S{sub 1/2}{yields}4d{sup 10}6p {sup 2}P{sub 3/2} transition at 206 nm.

  20. Ionization and density along the beams of Herbig-Haro jets

    NASA Astrophysics Data System (ADS)

    Bacciotti, Francesca; Eislöffel, Jochen

    1999-02-01

    Physical properties of several well-known Herbig-Haro jets are investigated using an improved version of the spectroscopic diagnostic technique originally developed by Bacciotti et al. ( te{bco95}). The procedure allows one to derive in a model-independent way the hydrogen ionization fraction in regions of low excitation. The ionization fraction, the electron and gas density, and the average excitation temperature are derived for various positions along the flows. We find that the hydrogen ionization fraction, with typical initial values of 20-30%, generally decreases along the whole jet or along parts of the flow, following well-defined recombination laws. These results are consistent with the idea that the gas is initially ionized in the jet acceleration region, and then slowly recombines while traveling away from the source. If shocks along the jet beam are present, they can at most have a minor contribution to the ionization of the gas, as apparent in HH 34 and in the first 45\\arcsec of the HH 46/47 jet, where the ionization fraction decreases almost monotonically. In the jets in which re-ionization episodes occur (i.e. HH 24C/E and HH 24G), the ionization fraction suddenly increases and then gently decays downstream of the re-ionization event. Both findings apparently disfavour a mini-bow shock interpretation for the production of the ionization of the beam. The total densities derived from the ratio between the electron density and the ionization fraction range from about 10(3) to a few 10(4) cm(-3) . Without applying a correction for shock compression, the average mass loss rate varies from 3.8 10(-8) (in the HL Tau jet) to 1.2 10(-6) Msun yr(-1) (in HH24 G), while momentum supply rates vary between 1.6 10(-5) (in the HL Tau jet) and 3.1 10(-4) Msun yr(-1) km s(-1) (in HH 24G). Taking shock compression into account, these values may be reduced by a factor 3-5.

  1. Aqueous solubility (in the range between 298.15 and 338.15 K), vapor pressures (in the range between 10(-5) and 80 Pa) and Henry's law constant of 1,2,3,4-dibenzanthracene and 1,2,5,6-dibenzanthracene.

    PubMed

    Abou-Naccoul, Ramy; Mokbel, Ilham; Bassil, Georgio; Saab, Joseph; Stephan, Khaled; Jose, Jacques

    2014-01-01

    Aqueous solubility and vapor pressures of 1,2,3,4-dibenzanthracene and 1,2,5,6-dibenzanthracene were determined using dynamic saturation methods. For the two isomers, aqueous solubility is in the range between 10(-10) and 10(-2) in molar fraction corresponding to temperature between 298.15 and 338.15K. Vapor pressures of the pure solutes range from 10(-5) to 80 Pa. Prior to the study of the two dibenzanthracenes and in order to check the experimental procedures, solubility of fluoranthene (between 298 and 338 K) and vapor pressures of phenanthrene and fluoranthene (between 300 and 470 K) were measured. From aqueous solubility data coupled with the vapor pressures of the pure solutes, partition coefficient air-water, KAW, and Henry's constant, KH, of environmental relevance were calculated.

  2. Circumstellar Interaction in SN 1993J

    NASA Astrophysics Data System (ADS)

    Fransson, Claes; Lundqvist, Peter; Chevalier, Roger A.

    1996-04-01

    The radio and X-ray observations of SN 1993J during the first year can be consistently explained as a result of interaction of the expanding ejecta with a circumstellar medium. The density of the circumstellar gas can be deduced from the free-free absorption of the radio emission and from the X-ray luminosity. During the first 2 weeks, both sets of observations indicate a mass loss-rate of ~4 x 10^-5^ M_sun_ yr^-1^ for a wind velocity of 10 km s^-1^. The subsequent radio and X-ray observations indicate a density gradient is proportional to r^-s^, with 1.5 <~ s <~ 1.7, as opposed to the r^-2^ gradient expected for a steady, spherically symmetric wind. This may be caused either by a variation of the mass-loss rate from the progenitor System or by a non-spherically symmetric geometry. To explain the properties of the X-ray emission, a steep density gradient in the ejecta is needed. During the first months, most of the observed X-ray emission originates from the circumstellar shock, which is adiabatic, while the reverse shock is radiative. To avoid excessive Comptonization in the X-ray range collisionless heating must be ineffective. The soft X-rays observed at 220 days probably originate from the reverse shock. The ionization and temperature structures of the circumstellar gas are calculated; we find that the temperature is in excess of 10^5^ K and the medium is nearly completely ionized by the shock radiation after the formation of the shocks. Preacceleration of the circumstellar gas by the radiation from the outbreak can explain the observed high velocity for the circumstellar N V and Hα lines. The high luminosity of the lines indicates that the circumstellar medium close to the supernova progenitor had a complex structure.

  3. 46 CFR 39.10-5 - Incorporation by reference-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... for incorporation by reference in this part, and the sections affected are: American Petroleum... Specification for Spill Valves for Use in Marine Tank Liquid Overpressure Protection Applications...

  4. 19 CFR 10.5 - Shooks and staves; cloth boards; port director's account.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) Shooks and staves produced in the United States and returned in the form of complete boxes or barrels in... country are ready to be assembled into boxes or barrels without further cutting to size; except that box shooks may be exported in double lengths and cut abroad. The number of boxes made from such shooks...

  5. 46 CFR 34.10-5 - Fire pumps-T/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... stations Interior stations 100 (1) 100 250 2 1 3 2 11/2 11/2 250 400 2 3 2 11/2 11/2 400 650 2 3 2 4 21/2.... (Refer to Table 34.50-5(c).) 2 Vessels of 1,000 gross tons and over on an international voyage shall have... international voyage, each required fire pump, while delivering water through the fire main system at a...

  6. 46 CFR 34.10-5 - Fire pumps-T/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... stations Interior stations 100 (1) 100 250 2 1 3 2 11/2 11/2 250 400 2 3 2 11/2 11/2 400 650 2 3 2 4 21/2.... (Refer to Table 34.50-5(c).) 2 Vessels of 1,000 gross tons and over on an international voyage shall have... international voyage, each required fire pump, while delivering water through the fire main system at a...

  7. 46 CFR 54.10-5 - Maximum allowable working pressure (reproduces UG-98).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... reference; see 46 CFR 54.01-1.) (b) The maximum allowable working pressure for a vessel part is the maximum... loadings listed in UG-22 of section VIII of the ASME Boiler and Pressure Vessel Code (see 46 CFR 54.01-30) that are likely to occur, or the designated coincident operating temperature, excluding any...

  8. 46 CFR 54.10-5 - Maximum allowable working pressure (reproduces UG-98).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... reference; see 46 CFR 54.01-1.) (b) The maximum allowable working pressure for a vessel part is the maximum... loadings listed in UG-22 of section VIII of the ASME Boiler and Pressure Vessel Code (see 46 CFR 54.01-30) that are likely to occur, or the designated coincident operating temperature, excluding any...

  9. 20 CFR 10.5 - What definitions apply to the regulations in this subchapter?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) Occupational disease or illness means a condition produced by the work environment over a period longer than a... previous injury or illness without an intervening injury or new exposure to the work environment that caused the illness. This term also means an inability to work that takes place when a...

  10. 20 CFR 10.5 - What definitions apply to the regulations in this subchapter?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) Occupational disease or illness means a condition produced by the work environment over a period longer than a... previous injury or illness without an intervening injury or new exposure to the work environment that caused the illness. This term also means an inability to work that takes place when a...

  11. 20 CFR 10.5 - What definitions apply to the regulations in this subchapter?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) Occupational disease or illness means a condition produced by the work environment over a period longer than a... previous injury or illness without an intervening injury or new exposure to the work environment that caused the illness. This term also means an inability to work that takes place when a...

  12. 20 CFR 10.5 - What definitions apply to these regulations?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... hospital. (q) Occupational disease or Illness means a condition produced by the work environment over a... medical condition which had resulted from a previous injury or illness without an intervening injury or new exposure to the work environment that caused the illness. This term also means an inability...

  13. 20 CFR 10.5 - What definitions apply to these regulations?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... hospital. (q) Occupational disease or Illness means a condition produced by the work environment over a... medical condition which had resulted from a previous injury or illness without an intervening injury or new exposure to the work environment that caused the illness. This term also means an inability...

  14. General Counsel`s office FY 1995 site support program plan WBS 6.10.5

    SciTech Connect

    Moreno, S.R.

    1994-09-01

    The General Counsel`s office provides legal counsel to all levels of WHC management; administers the intellectual property program; coordinates all WHC investigative activity and supports WHC activities to ensure compliance with all applicable federal, state, and local laws, DOE directives, contractual provisions, and other requirements. In so doing, the Office of General Counsel supports the Hanford site mission of transforming the Hanford site into an environmentally attractive and economically sustainable community. This document briefs the FY95 site support plan.

  15. Radiology Technician, 10-5. Military Curriculum Materials for Vocational and Technical Education.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. National Center for Research in Vocational Education.

    These five volumes of student materials for a secondary/postsecondary level course in radiology technology comprise one of a number of military-developed curriculum packages selected for adaptation to vocational instruction and curriculum development in a civilian setting. The purpose stated for the course is to provide the theory portion of…

  16. 46 CFR 31.10-5 - Inspection of new tank vessels-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... regulations in this chapter. For list of electrical plans see subchapter J (Electrical Engineering) of this... home office is located at 321 West 44th Street, New York, NY 10036, on the Internet at...

  17. 46 CFR 31.10-5 - Inspection of new tank vessels-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... regulations in this chapter. For list of electrical plans see subchapter J (Electrical Engineering) of this... home office is located at 321 West 44th Street, New York, NY 10036, on the Internet at...

  18. 46 CFR 39.10-5 - Incorporation by reference-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 2nd St. SW., Stop 7126, Washington, DC 20593-7126, or at the National Archives and Records... for incorporation by reference in this part, and the sections affected are: American Petroleum Institute (API), 1220 L Street NW., Washington, DC 20005 API Standard 2000, Venting Atmospheric and...

  19. 46 CFR 39.10-5 - Incorporation by reference-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 2nd St. SW., Stop 7126, Washington, DC 20593-7126, or at the National Archives and Records... for incorporation by reference in this part, and the sections affected are: American Petroleum Institute (API), 1220 L Street NW., Washington, DC 20005 API Standard 2000, Venting Atmospheric and...

  20. DES of turbulent vortex breakdown in an abrupt axisymmetric expansion at Re = 10^5.

    NASA Astrophysics Data System (ADS)

    Paik, Joongcheol; Sotiropoulos, Fotis

    2007-11-01

    Turbulent swirling incompressible flow through an abrupt axisymmetric expansion at Re = 100,000 is investigated numerically using detached-eddy simulation. The effects of swirl intensity on the coherent dynamics of the flow are systematically studied by carrying out numerical simulations over a range of swirl numbers from 0.17 to 1.23. Comparisons of computed solutions and the experimental measurements of Dellenback et al. [AIAA Journal. Vol 26, pp. 669-681] show that the numerical simulations resolve both axial and swirling mean velocity profiles and corresponding turbulence statistics with very good accuracy. Coherent structure visualizations with the q-criterion and Lagrangian particle tracking are used to elucidate the rich dynamics of the flow as a function of the swirl number with emphasis on the various modes of vortex breakdown and other large scale instabilities in the shear layers and along the pipe wall.

  1. Stationary Engineers Apprenticeship. Related Training Modules. 10.1-10.5 Machine Components.

    ERIC Educational Resources Information Center

    Lane Community Coll., Eugene, OR.

    This packet of five learning modules on machine components is one of 20 such packets developed for apprenticeship training for stationary engineers. Introductory materials are a complete listing of all available modules and a supplementary reference list. Each module contains some or all of these components: goal, performance indicators, statement…

  2. The 3-D ionization structure of the planetary nebula NGC 6565

    NASA Astrophysics Data System (ADS)

    Turatto, M.; Cappellaro, E.; Ragazzoni, R.; Benetti, S.; Sabbadin, F.

    2002-03-01

    ), which has been ejected by an equatorial enhanced superwind of 4 (+/-2) x 10-5 Msun yr-1 lasted for 4 (+/-2) x 103 years. Based on observations made with ESO Telescopes at the La Silla Observatories, under programme ID 65.I-0524, and on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Institute (observing program GO 7501; P.I. Arsen Hajian). STScI is operated by the association of Universities for Research in Astronomy, Inc. under the NASA contract NAS 5-26555. We have applied the photoionization code CLOUDY, developed at the Institute of Astronomy of the Cambridge University.

  3. An optical and near-IR spectroscopic study of the extreme P Cygni-type supergiant HDE 316285

    NASA Astrophysics Data System (ADS)

    Hillier, D. J.; Crowther, P. A.; Najarro, F.; Fullerton, A. W.

    1998-12-01

    A detailed study of the Galactic P Cygni-type supergiant HDE 316285, based on high quality optical (AAT, MSO, CTIO) and near-IR (UKIRT, CFHT, CTIO) spectroscopy, is presented. As has been noted previously, its spectrum is dominated by H, He I, and Fe Ii P Cygni profiles. Emission lines due to N I, N Ii, [N Ii], O I, Na I, Mg Ii, Al Ii, Ca Ii, Si Ii, Si Iii, Fe Ii and [Fe Ii] can also be readily identified. Many of the metal lines are produced by continuum fluorescence. The rich N spectrum, the paucity of the O spectrum (only 2 O lines can be identified), and the apparent absence of emission due to C, strongly suggest that the atmosphere of the star is contaminated by CNO processed material. A comparison of the spectrum of HDE 316285 with P Cygni and He 3-519 is presented. From a spectral analysis using the non-LTE atmosphere code of Hillier (1991), and assuming a distance of 1.85 kpc, our preferred model for HDE 316285 has the following parameters: T_* = 15 kK, log L_* / L_sun = 5.44, spose M = 2.4 x 10(-4) Msun yr(-1) , v_∞ = 410 {km s(-1) }, E_B-V=1.81 mag, and H/He ~ 1.5 by number. Due to the low degree of He ionization the derived H/He abundance ratio and mass-loss rate are strongly coupled. Models with H/He=10 to 0.5 are equally capable of explaining the H and He I\\ spectrum provided the mass-loss rate is scaled according to the approximate formula spose M = 9.1 + 26.3 (He/H -0.1) x 10(-5) M_{\\odot}yr. Preliminary work, however, indicates that a solar H/He ratio can be ruled out on the basis of line strengths of other species - particularly N, Mg, Al. The stellar wind from HDE 316285 is more extreme than P Cygni with a performance number (= ratio of wind momentum to radiative momentum) 30 times greater. The low H/He abundance ratio and high N/He abundance ratio confirms that HDE 316285 is evolved. Although we find no evidence in the literature for photometric variability, we find strong evidence for significant spectral variability. Because of the spectral

  4. General Counsel`s Office FY 1996 Site Support Program Plan: WBS 6.10.5. Revision 1

    SciTech Connect

    Moreno, S.R.

    1995-09-01

    This is the General Counsel`s Office site support program plan for the US DOE Hanford site. The topics addressed in the program plan include a mission statement, description of activities, program objectives, planning assumptions, program constraints, work breakdown structure, milestone list, milestone description sheets, and activity detail.

  5. Serum level of miR-10-5p as a prognostic biomarker for acute myeloid leukemia.

    PubMed

    Zhi, Yongjin; Xie, Xiaobao; Wang, Rong; Wang, Biao; Gu, Weiying; Ling, Yun; Dong, Weimin; Zhi, Feng; Liu, Yan

    2015-09-01

    MicroRNAs (miRNAs) are a type of small non-coding RNA molecule that play important roles in tumor initiation, chemotherapy response, promotion, and progression by negatively interfering with gene expression. The aim of the present study was to investigate the serum expression status and explore the prognostic significance of miR-10a-5p in acute myeloid leukemia (AML). The serum expression level of miR-10a-5p in de novo AML was significantly higher, compared with that in controls. The area under the receiver operator characteristic (ROC) curve was of 0.831 in the diagnostic value of miR-10a-5p. In the complete remission (CR) group, the serum expression level of miR-10a-5p was similar to that of healthy subjects and demonstrated a significant downtrend when compared to that on the day of diagnosis. Nevertheless, miR-10a-5p expression was found to significantly increase in cases of relapsed AML when compared individually to the CR population. On analysis of the association of miR-10a-5p expression with the clinical characteristics at diagnosis in AML patients, lower CR rates occurred more frequently in the high-expression group. In addition, high miR-10a-5p expression was associated with poorer overall survival (OS). These data suggest that miR-10a-5p may serve as a biomarker useful to improving the management of AML patients. PMID:26134365

  6. 31 CFR 10.5 - Application to become an enrolled agent, enrolled retirement plan agent, or registered tax return...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... tax return preparer. See 26 CFR part 300. (c) Additional information; examination. The Internal... applicant's tax liabilities. (e) Temporary recognition. On receipt of a properly executed application, the Commissioner, or delegate, may grant the applicant temporary recognition to practice pending a determination...

  7. 31 CFR 10.5 - Application to become an enrolled agent, enrolled retirement plan agent, or registered tax return...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... tax return preparer. See 26 CFR part 300. (c) Additional information; examination. The Internal... applicant's tax liabilities. (e) Temporary recognition. On receipt of a properly executed application, the Commissioner, or delegate, may grant the applicant temporary recognition to practice pending a determination...

  8. 31 CFR 10.5 - Application for enrollment as an enrolled agent or enrolled retirement plan agent.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... accordance with 26 CFR 300.5. A reasonable nonrefundable fee will be charged for each application for... enrollment. (d) Temporary recognition. On receipt of a properly executed application, the Director of the Office of Professional Responsibility may grant the applicant temporary recognition to practice pending...

  9. 31 CFR 10.5 - Application for enrollment as an enrolled agent or enrolled retirement plan agent.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Professional Responsibility in accordance with 26 CFR 300.5. A reasonable nonrefundable fee will be charged for... his or her application for enrollment. (d) Temporary recognition. On receipt of a properly executed... recognition to practice pending a determination as to whether enrollment to practice should be...

  10. 31 CFR 10.5 - Application to become an enrolled agent, enrolled retirement plan agent, or registered tax return...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... tax return preparer. See 26 CFR part 300. (c) Additional information; examination. The Internal... applicant's tax liabilities. (e) Temporary recognition. On receipt of a properly executed application, the Commissioner, or delegate, may grant the applicant temporary recognition to practice pending a determination...

  11. 22 CFR 19.10-5 - Reduced annuity with additional survivor annuity to spouse or former spouse.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... agreement conforms to the law and regulations) or such later date as may be specified in the agreement. No... divorce from the principal and failure to meet the definition of “former spouse,” or in the event of...

  12. Orbital period variation of the eclipsing binary system TT Herculis

    NASA Astrophysics Data System (ADS)

    Selam, S. O.; Albayrak, B.

    2007-02-01

    % New photoelectric U BV observations were obtained for the eclipsing binary TT Her at the Ankara University Observatory (AUO) and three new times of minima were calculated from these observations. The (O-C) diagram constructed for all available times of minima of TT Her exhibits a cyclic character superimposed on a quadratic variation. The quadratic character yields an orbital period decrease with a rate of dP/dt=-8.83×10-8 day yr-1 which can be attributed to the mass exchange/loss mechanism in the system. By assuming the presence of a gravitationally bound third body in the system, the analysis of the cyclic nature in the (O-C) diagram revealed a third body with a mass of 0.21 M\\sun orbiting around the eclipsing pair. The possibility of magnetic activity cycle effect as a cause for the observed cyclic variation in the (O-C) diagram was also discussed.

  13. Dry deposition of nitrogen compounds (NO2, HNO3, NH3), sulfur dioxide and ozone in West and Central African ecosystems using the inferential method

    NASA Astrophysics Data System (ADS)

    Adon, M.; Galy-Lacaux, C.; Yoboue, V.; Delon, C.; Solmon, F.; Kaptue Tchuente, A. T.

    2013-05-01

    This work is part of the IDAF program (IGAC-DEBITS-AFRICA) and is based on the long term monitoring of gas concentrations (1998-2007) established on seven remote sites representative of major African ecosystems. Dry deposition fluxes were estimated by the inferential method using on one hand surface measurements of gas concentrations (NO2, HNO3, NH3, SO2, and O3) and on the other hand simulated dry deposition velocities (Vd). Vd were calculated using the big-leaf model of Zhang et al. (2003b). In the model of deposition, surface and meteorological conditions specific to IDAF sites have been adapted in order to simulate Vd representative of major African ecosystems. The monthly, seasonal and annual mean variations of gaseous dry deposition fluxes (NO2, HNO3, NH3, O3, and SO2) are analyzed. Along the latitudinal transect of ecosystems, the annual mean dry deposition fluxes of nitrogen compounds range from 0.4 ± 0.0 to 0.8 ± 0.2 kg N ha-1 yr-1 for NO2, from 0.7 ± 0.1 to 1.0 ± 0.3 kg N ha-1 yr-1 for HNO3, and from 2.3 ± 0.8 to 10.5 ± 5.0 kg N ha-1 yr-1 for NH3 over the study period (1998-2007). The total nitrogen dry deposition flux (NO2+HNO3+NH3) is more important in forests (11.2-11.8 kg N ha-1 yr-1) than in wet and dry savannas (3.4-5.3 kg N ha-1 yr-1). NH3 dominated nitrogen dry deposition, representing 67-80% of the total. The annual mean dry deposition fluxes of ozone range between 11.3 ± 4.7 and 17.5 ± 3.0 kg ha-1 yr-1 in dry savannas, 17.5 ± 3.0 and 19.2 ± 2.9 kg ha-1 yr-1 in wet savannas, and 10.6 ± 2.0 and 13.2 ± 3.6 kg ha-1 yr-1 in forests. Lowest O3 dry deposition fluxes in forests are correlated to low measured O3 concentrations, lower of a factor of 2-3, compared to others ecosystems. Along the ecosystem transect, annual mean of SO2 dry deposition fluxes present low values and a small variability (0.5 to 1 kg S ha-1 yr-1). No specific trend in the interannual variability of these gaseous dry deposition fluxes is observed over the study period.

  14. Condensation of Dust around the WC7 Star HD192641 = WR137

    NASA Astrophysics Data System (ADS)

    Williams, P. M.; Longmore, A. J.; van der Hucht, K. A.; Talevera, A.; Wamsteker, W. M.; Abbott, D. C.; Telesco, C. M.

    1985-07-01

    The WC7+ absorption class Wolf-Rayet star WR 137 (=HD 192641) is shown to have brightened significantly in the infrared since 1978, most rapidly between 1983 and mid-1984. This is ascribed to an increase in the mass loss rate and the condensation of dust grains in the stellar wind. At maximum, the dust mass was about 10-8 Msun with a formation rate near 10-7 Msun yr-1, about 0.5 per cent of the mass loss rate. This was not accompanied by any strengthening of the 2200 Å absorption feature measured by the IUE between 1980 and 1984 although the shell was too weak to rule out any connection between the 2200 Å absorption feature and the carbon grains presumed to comprise the shell. The fading of WR 137 in the infrared between 1973 and 1978 may have been due to the dissipation of an earlier dust shell and WR 137 may resemble WR 140 (=HD 193793, also WC7+abs) in showing sporadic dust formation episodes.

  15. Classical T Tauri-like Outflow Activity in the Brown Dwarf Mass Regime

    NASA Astrophysics Data System (ADS)

    Whelan, E. T.; Ray, T. P.; Bacciotti, F.; Podio, L.; Randich, S.

    2010-11-01

    Since 2005 we have been analysing the spectra of brown dwarfs (BDs) using the technique of spectro-astrometry and to date have found 5 outflows driven by BDs. Our aim is to obtain an understanding of outflow activity in the BD mass regime and make a comprehensive comparison with low mass protostars, in particular the classical T Tauri stars (CTTSs). Table 1 summarises some results for the sources in our sample. Also see Whelan et al. (2009b) for a complete discussion and comparison with CTTSs. Some noteworthy results include the asymmetry in the ISO-217 bipolar outflow which is revealed in the relative brightness of the two lobes (red-shifted lobe is brighter) and the factor of two difference in radial velocity (the red-shifted lobe is faster). Asymmetries are common in jets from low mass protostars (0.1 Msun to 2 Msun) and the observation of a strong asymmetry at such a low mass supports the idea that BD outflow activity is scaled down from CTTSs. In addition, Whelan et al. (2009a) find a strong contribution to the Hα line emitted by LS-RCrA 1 and evidence of a dust hole in its disk. Using methods previously applied to CTTS Whelan et al. (2009b) estimate the mass outflow rate (Ṁout) for LS-RCrA 1, ISO and ISO-Oph 102 Ṁout to be in the range 10-10 to 10-9 Msun yr-1 which is comparable to measured mass accretion rates.

  16. Climatic variability, hydrologic anomaly, and methane emission can turn productive freshwater marshes into net carbon sources.

    PubMed

    Chu, Housen; Gottgens, Johan F; Chen, Jiquan; Sun, Ge; Desai, Ankur R; Ouyang, Zutao; Shao, Changliang; Czajkowski, Kevin

    2015-03-01

    Freshwater marshes are well-known for their ecological functions in carbon sequestration, but complete carbon budgets that include both methane (CH4 ) and lateral carbon fluxes for these ecosystems are rarely available. To the best of our knowledge, this is the first full carbon balance for a freshwater marsh where vertical gaseous [carbon dioxide (CO2 ) and CH4 ] and lateral hydrologic fluxes (dissolved and particulate organic carbon) have been simultaneously measured for multiple years (2011-2013). Carbon accumulation in the sediments suggested that the marsh was a long-term carbon sink and accumulated ~96.9 ± 10.3 (±95% CI) g C m(-2)  yr(-1) during the last ~50 years. However, abnormal climate conditions in the last 3 years turned the marsh to a source of carbon (42.7 ± 23.4 g C m(-2)  yr(-1) ). Gross ecosystem production and ecosystem respiration were the two largest fluxes in the annual carbon budget. Yet, these two fluxes compensated each other to a large extent and led to the marsh being a CO2 sink in 2011 (-78.8 ± 33.6 g C m(-2)  yr(-1) ), near CO2 -neutral in 2012 (29.7 ± 37.2 g C m(-2)  yr(-1) ), and a CO2 source in 2013 (92.9 ± 28.0 g C m(-2)  yr(-1) ). The CH4 emission was consistently high with a three-year average of 50.8 ± 1.0 g C m(-2)  yr(-1) . Considerable hydrologic carbon flowed laterally both into and out of the marsh (108.3 ± 5.4 and 86.2 ± 10.5 g C m(-2)  yr(-1) , respectively). In total, hydrologic carbon fluxes contributed ~23 ± 13 g C m(-2)  yr(-1) to the three-year carbon budget. Our findings highlight the importance of lateral hydrologic inflows/outflows in wetland carbon budgets, especially in those characterized by a flow-through hydrologic regime. In addition, different carbon fluxes responded unequally to climate variability/anomalies and, thus, the total carbon budgets may vary drastically among years.

  17. Mass accretion flows in the high-mass star forming complex NGC 6334

    NASA Astrophysics Data System (ADS)

    Sánchez-Monge, Á.; Schilke, P.; Zernickel, A.; Schmiedeke, A.; Möller, Th.; Qin, S.-L.

    2016-05-01

    The formation of high-mass stars is one of the major topics of astrophysical research, in particular the process of accretion from large-scale clouds down to small-scale cores. We have selected the nearby, filamentary, high-mass star forming complex NGC 6334 to study the gas velocity at different scales and probe the infall rates onto the protostellar cores embedded in the NGC 6334-I and I(N) clusters. This study makes use of single-dish and interferometric submillimeter observations, complemented with 3D numerical non-LTE radiative transfer modeling. We measure a mass accretion rate of 10-5 M⊙ yr-1 throughout the filament increasing up to 10-3 M⊙ yr-1 towards the densest regions where high-mass stars are forming. At smaller scales, our 3D model is consistent with accretion rates of 10-3 M⊙ yr-1 towards the clusters, and 10-4 M⊙ yr-1 onto the protostars.

  18. Global cost estimates of reducing carbon emissions through avoided deforestation.

    PubMed

    Kindermann, Georg; Obersteiner, Michael; Sohngen, Brent; Sathaye, Jayant; Andrasko, Kenneth; Rametsteiner, Ewald; Schlamadinger, Bernhard; Wunder, Sven; Beach, Robert

    2008-07-29

    Tropical deforestation is estimated to cause about one-quarter of anthropogenic carbon emissions, loss of biodiversity, and other environmental services. United Nations Framework Convention for Climate Change talks are now considering mechanisms for avoiding deforestation (AD), but the economic potential of AD has yet to be addressed. We use three economic models of global land use and management to analyze the potential contribution of AD activities to reduced greenhouse gas emissions. AD activities are found to be a competitive, low-cost abatement option. A program providing a 10% reduction in deforestation from 2005 to 2030 could provide 0.3-0.6 Gt (1 Gt = 1 x 10(5) g) CO(2).yr(-1) in emission reductions and would require $0.4 billion to $1.7 billion.yr(-1) for 30 years. A 50% reduction in deforestation from 2005 to 2030 could provide 1.5-2.7 Gt CO(2).yr(-1) in emission reductions and would require $17.2 billion to $28.0 billion.yr(-1). Finally, some caveats to the analysis that could increase costs of AD programs are described.

  19. Future carbon balance of China's forests under climate change and increasing CO2.

    PubMed

    Ju, W M; Chen, J M; Harvey, D; Wang, S

    2007-11-01

    negative effect of climate change after 2050. Under the CGCM2-A2 climate scenario and with direct CO(2) effects, China's forests may be a small C source of 7.6 Tg C yr(-1) during 2091-2100. Most forests act as C sources of 0-40 g Cm(-2)yr(-1). Under the CGCM2-B2 climate scenario and with direct CO(2) effects, China's forests might be a small C sink of 10.5 Tg C yr(-1) during 2091-2100, with C sequestration of most forests ranging from 0 to 40 g Cm(-2)yr(-1). Stand age structure plays a more dominant role in determining future C sequestration than CO(2) and climate change. The prediction of future C sequestration of China's forests is very sensitive to the Q(10) value used to estimate maintenance respiration and to soil water availability and less sensitive to N deposition scenario. The results are not yet comprehensive, as no forest disturbance data were available or predicted after 2001. However, the results indicate a range of possible responses of the C balance of China's forests to various scenarios of increase in CO(2) and climate change. These results could be useful for assessing measures to mitigate climate change through reforestation. PMID:17187919

  20. Lateral distribution of high energy muons in EAS of sizes Ne approximately equals 10(5) and Ne approximately equals 10(6)

    NASA Technical Reports Server (NTRS)

    Bazhutov, Y. N.; Ermakov, G. G.; Fomin, G. G.; Isaev, V. I.; Jarochkina, Z. V.; Kalmykov, N. N.; Khrenov, B. A.; Khristiansen, G. B.; Kulikov, G. V.; Motova, M. V.

    1985-01-01

    Muon energy spectra and muon lateral distribution in EAS were investigated with the underground magnetic spectrometer working as a part of the extensive air showers (EAS) array. For every registered muon the data on EAS are analyzed and the following EAS parameters are obtained, size N sub e, distance r from the shower axis to muon, age parameter s. The number of muons with energy over some threshold E associated to EAS of fixed parameters are measured, I sub reg. To obtain traditional characteristics, muon flux densities as a function of the distance r and muon energy E, muon lateral distribution and energy spectra are discussed for hadron-nucleus interaction model and composition of primary cosmic rays.

  1. The corrosion of etched magnox Al-80 in dry steam at ˜ 10 5 Pa pressure in the temperature range 373-573 K

    NASA Astrophysics Data System (ADS)

    Friskney, C. A.

    1981-09-01

    The corrosion of magnox in dry steam has been studied isothermally in the temperature range 373-573 K. Within this range different products dominate the process and there are corresponding rate changes. At ~520 K and above the product is magnesium oxide, whilst below ~ 393 K magnesium hydroxide is produced, the corrosion rate increasing with temperature in both regimes. Although magnesium hydroxide remains the dominant reaction product from 395 to 497 K, the rate of corrosion passes through a maximum at ~ 409 K and then falls rapidly as temperature is increased to ~ 520 K. Above 440 K magnesium hydride is detectable in the corrosion product, the amount increasing with temperature. It is suggested that hydrogen is built up in traps near the metal surface to form hydride and the hydride/hydrogen slows the hydroxide production. Formation of magnesium oxide appears to be a relatively slow process compared with hydroxide formation.

  2. FINAL REPORT INTEGRATED DM1200 MELTER TESTING OF BUBBLER CONFIGURATIONS USING HLW AZ-101 SIMULANTS VSL-04R4800-4 REV 0 10/5/04

    SciTech Connect

    KRUGER AA; MATLACK KS; GONG W; BARDAKCI T; D'ANGELO NA; LUTZE W; CALLOW RA; BRANDYS M; KOT WK; PEGG IL

    2011-12-29

    This report documents melter and off-gas performance results obtained on the DM1200 HLW Pilot Melter during processing of AZ-101 HLW simulants. The tests reported herein are a subset of six tests from a larger series of tests described in the Test Plan for the work; results from the other tests have been reported separately. The solids contents of the melter feeds were based on the WTP baseline value for the solids content of the feeds from pretreatment which changed during these tests from 20% to 15% undissolved solids resulting in tests conducted at two feed solids contents. Based on the results of earlier tests with single outlet 'J' bubblers, initial tests were performed with a total bubbling rate of 651 pm. The first set of tests (Tests 1A-1E) addressed the effects of skewing this total air flow rate back and forth between the two installed bubblers in comparison to a fixed equal division of flow between them. The second set of tests (2A-2D) addressed the effects of bubbler depth. Subsequently, as the location, type and number of bubbling outlets were varied, the optimum bubbling rate for each was determined. A third (3A-3C) and fourth (8A-8C) set of tests evaluated the effects of alternative bubbler designs with two gas outlets per bubbler instead of one by placing four bubblers in positions simulating multiple-outlet bubblers. Data from the simulated multiple outlet bubblers were used to design bubblers with two outlets for an additional set of tests (9A-9C). Test 9 was also used to determine the effect of small sugar additions to the feed on ruthenium volatility. Another set of tests (10A-10D) evaluated the effects on production rate of spiking the feed with chloride and sulfate. Variables held constant to the extent possible included melt temperature, plenum temperature, cold cap coverage, the waste simulant composition, and the target glass composition. The feed rate was increased to the point that a constant, essentially complete, cold cap was achieved, which was used as an indicator of a maximized feed rate for each test. The first day of each test was used to build the cold cap and decrease the plenum temperature. The remainder of each test was split into two- to six-day segments, each with a different bubbling rate, bubbler orientation, or feed concentration of chloride and sulfur.

  3. Astronomical constraints on the cosmic evolution of the fine structure constant and possible quantum dimensions.

    PubMed

    Carilli, C L; Menten, K M; Stocke, J T; Perlman, E; Vermeulen, R; Briggs, F; de Bruyn, A G; Conway, J; Moore, C P

    2000-12-25

    We present measurements of absorption by the 21 cm hyperfine transition of neutral hydrogen toward radio sources at substantial look-back times. These data are used in combination with observations of rotational transitions of common interstellar molecules to set limits on the evolution of the fine structure constant: alpha/ alpha<3.5x10(-15) yr(-1), to a look-back time of 4.8 Gyr. In the context of string theory, the limit on the secular evolution of the scale factor of the compact dimensions, R, is &Rdot/ R<10(-15) yr(-1). Including terrestrial and other astronomical measurements places 2sigma limits on slow oscillations of R from the present to the epoch of cosmic nucleosynthesis, just seconds after the big bang, of DeltaR /R<10(-5).

  4. Astronomical constraints on the cosmic evolution of the fine structure constant and possible quantum dimensions.

    PubMed

    Carilli, C L; Menten, K M; Stocke, J T; Perlman, E; Vermeulen, R; Briggs, F; de Bruyn, A G; Conway, J; Moore, C P

    2000-12-25

    We present measurements of absorption by the 21 cm hyperfine transition of neutral hydrogen toward radio sources at substantial look-back times. These data are used in combination with observations of rotational transitions of common interstellar molecules to set limits on the evolution of the fine structure constant: alpha/ alpha<3.5x10(-15) yr(-1), to a look-back time of 4.8 Gyr. In the context of string theory, the limit on the secular evolution of the scale factor of the compact dimensions, R, is &Rdot/ R<10(-15) yr(-1). Including terrestrial and other astronomical measurements places 2sigma limits on slow oscillations of R from the present to the epoch of cosmic nucleosynthesis, just seconds after the big bang, of DeltaR /R<10(-5). PMID:11136034

  5. Direct Detections of Young Stars in Nearby Elliptical Galaxies

    NASA Astrophysics Data System (ADS)

    Ford, H. Alyson; Bregman, Joel N.

    2013-06-01

    Small amounts of star formation in elliptical galaxies are suggested by several results: surprisingly young ages from optical line indices, cooling X-ray gas, and mid-infrared dust emission. Such star formation has previously been difficult to directly detect, but using ultraviolet Hubble Space Telescope Wide Field Camera 3 imaging, we have identified individual young stars and star clusters in four nearby ellipticals. Ongoing star formation is detected in all galaxies, including three ellipticals that have previously exhibited potential signposts of star-forming conditions (NGC 4636, NGC 4697, and NGC 4374), as well as the typical "red and dead" NGC 3379. The current star formation in our closest targets, where we are most complete, is between 2.0 and 9.8 × 10-5 M ⊙ yr-1. The star formation history was roughly constant from 0.5 to 1.5 Gyr (at (3-5) × 10-4 M ⊙ yr-1), but decreased by a factor of several in the past 0.3 Gyr. Most star clusters have a mass between 102 and 104 M ⊙. The specific star formation rates of ~10-16 yr-1 (at the present day) or ~10-14 yr-1 (when averaging over the past Gyr) imply that a fraction 10-8 of the stellar mass is younger than 100 Myr and 10-5 is younger than 1 Gyr, quantifying the level of frosting of recent star formation over the otherwise passive stellar population. There is no obvious correlation between either the presence or spatial distribution of postulated star formation indicators and the star formation we detect. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program 11583.

  6. The Nature of Irac-selected Extremely Red Objects

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Huang, J.; Gu, Q.

    2010-05-01

    Using deep U-8um photometry from GEMs, MUSYC and SIMPLE surveys, we investigate properties of a large sample of IRAC-selected extremely red galaxies(IEROs). The sample comprises 304 brightest IEROs distributed over the GEMS field with a total area of 800 arcmin2, which satisfy ([3.6]+[4.5]/2)<21.2 and z-[3.6] > 3.25). Combined with the deepest Chandra and Spitzer surveys in this field, we are able to determine relative contributions of AGNs, (dusty) star-forming galaxies and passively evolving systems to the RED population; 51 sources are detected in at least one of three X-ray bands, leaving 253 non-Xray sources with 179 detected in 24um( 20uJy, 3sigma), indicating that at most 25% of these IEROs are passively evolving.We derive and examine photometric redshift using different methods; their redshift range from 1 to 2.6 with the median value at 1.5. Stellar masses of non-Xray sources are also derived with SED fitting methods, achieving a median value of 0.4*1011 Msun for a chrabrier initial mass function. The properties of best-fitting BC03 models are consistent with templates used for estimating redshifts, which have on average E(B-V) of 0.5 for 24um-deteced galaxies. The corresponding star-formation rates of these star-forming galaxies through SED fitting are within 40-100 Msun yr-1, consistent with that derived from their 24μm flux, which show a median total infrared luminosity 1*1011Lsun. We argue that such selected IEROs may represent a transient population from ULIRGs to LIRGs, and are likely descents of SMGs or DOGs.

  7. The VIRUS-P Exploration of Nearby Galaxies (VENGA): Radial Gas Inflow and Shock Excitation in NGC 1042

    NASA Astrophysics Data System (ADS)

    Luo, Rongxin; Hao, Lei; Blanc, Guillermo A.; Jogee, Shardha; van den Bosch, Remco C. E.; Weinzirl, Tim

    2016-06-01

    NGC 1042 is a late-type bulgeless disk galaxy that hosts low-luminosity active galactic nuclei (AGNs) coincident with a massive nuclear star cluster. In this paper, we present the integral field spectroscopy studies of this galaxy, based on the data obtained with the Mitchell spectrograph on the 2.7 m Harlan J. Smith telescope. In the central 100-300 pc region of NGC 1042, we find a circumnuclear ring structure of gas with enhanced ionization, which we suggest is mainly induced by shocks. Combining this with the harmonic decomposition analysis of the velocity field of the ionized gas, we propose that the shocked gas is the result of gas inflow driven by the inner spiral arms. The inflow velocity is ˜ 32+/- 10 {km} {{{s}}}-1, and the estimated mass-inflow rate is ˜ 1.1+/- 0.3× {10}-3 {M}⊙ {{yr}}-1. The mass-inflow rate is about one hundred times the black hole’s mass-accretion rate (˜ 1.4× {10}-5 {M}⊙ {{yr}}-1) and slightly larger than the star-formation rate in the nuclear star cluster (7.94× {10}-4 {M}⊙ {{yr}}-1), implying that the inflow material is enough to feed both the AGN activity and star formation in the nuclear star cluster. Our study highlights that secular evolution can be important in late-type unbarred galaxies like NGC 1042.

  8. The VIRUS-P Exploration of Nearby Galaxies (VENGA): Radial Gas Inflow and Shock Excitation in NGC 1042

    NASA Astrophysics Data System (ADS)

    Luo, Rongxin; Hao, Lei; Blanc, Guillermo A.; Jogee, Shardha; van den Bosch, Remco C. E.; Weinzirl, Tim

    2016-06-01

    NGC 1042 is a late-type bulgeless disk galaxy that hosts low-luminosity active galactic nuclei (AGNs) coincident with a massive nuclear star cluster. In this paper, we present the integral field spectroscopy studies of this galaxy, based on the data obtained with the Mitchell spectrograph on the 2.7 m Harlan J. Smith telescope. In the central 100–300 pc region of NGC 1042, we find a circumnuclear ring structure of gas with enhanced ionization, which we suggest is mainly induced by shocks. Combining this with the harmonic decomposition analysis of the velocity field of the ionized gas, we propose that the shocked gas is the result of gas inflow driven by the inner spiral arms. The inflow velocity is ˜ 32+/- 10 {km} {{{s}}}-1, and the estimated mass-inflow rate is ˜ 1.1+/- 0.3× {10}-3 {M}ȯ {{yr}}-1. The mass-inflow rate is about one hundred times the black hole’s mass-accretion rate (˜ 1.4× {10}-5 {M}ȯ {{yr}}-1) and slightly larger than the star-formation rate in the nuclear star cluster (7.94× {10}-4 {M}ȯ {{yr}}-1), implying that the inflow material is enough to feed both the AGN activity and star formation in the nuclear star cluster. Our study highlights that secular evolution can be important in late-type unbarred galaxies like NGC 1042.

  9. Deposition and leaching of sulfur, nitrogen and calcium in four forested catchments in China: implications for acidification.

    PubMed

    Larssen, Thorjørn; Duan, Lei; Mulder, Jan

    2011-02-15

    Here we present the first detailed study on fluxes of sulfur (S), nitrogen (N), and major cations in Chinese subtropical forest catchments. Data are from four study sites, differing in inputs of atmospheric pollutants and sensitivity to acidification. Results show important differences from most sites in North America and Europe. Dry deposition of S, N, and calcium (Ca) is considerably larger than wet deposition in most cases causing deposition fluxes ranging from moderate to very high, both for acidifying compounds (S deposition 1.5-10.5 kiloequivalents per hectare and year (keq ha(-1) yr(-1)); N deposition 0.4 to 2.5 keq ha(-1) yr(-1)) and for alkaline compounds (Ca deposition 0.8 to 5.7 keq ha(-1) yr(-1)). More than half of the input of acidity is neutralized by alkalinity associated with Ca deposition. Furthermore, the retention of incoming S and N is small in the soil root zone, but considerable in the deeper soils or riparian zone. Drainage water from the root zone of the soils at the two sites with the highest deposition show pronounced acidification. For the two sites with moderate deposition inputs, the root zones are retaining some of the incoming S and buffer some of the incoming acidity. The subsoils and the riparian zonesare strong sinks for N, S, and Ca. This is associated with substantial acid neutralization at all sites. These features are of major importance for the understanding of the long-term effects of acidification in China.

  10. Environmental impact from mountainous olive orchards under different soil-management systems (SE Spain).

    PubMed

    Francia Martínez, José R; Durán Zuazo, Víctor H; Martínez Raya, Armando

    2006-04-01

    Soil erosion, runoff and nutrient-loss patterns over a two-year period (1999-2000) were monitored in erosion plots on a mountainside with olive (Olea europaea cv. Picual) trees under three different types of soil management: (1) non-tillage with barley (Hordeum vulgare) strips of 4 m width (BS); (2) conventional tillage (CT); (3) non-tillage without plant strips (NT). The erosion plots, located in Lanjaron (Alpujarras) on the southern flank of the Sierra Nevada Mountains in south-eastern Spain, had 30% slope at an altitude of 565 m and 192 m(2) (24x8 m) in area. The highest erosion and runoff values, ranging from 10.5 to 40.7 t ha(-1) yr(-1) and from 26.5 to 51.5 mm yr(-1), respectively, over the entire study period, were measured under NT. In CT, erosion ranged from 1.0 to 10.4 t ha(-1) yr(-1) and runoff from 6.7 to 15.2 mm yr(-1), while under BS, erosion ranged from 1.7 to 2.4 t ha(-1) yr(-1) and runoff from 19.6 to 20.0 mm yr(-1). It is concluded that the BS and CT reduced the soil erosion by 92% and 78%, with respect to the NT, and the runoff by 49% and 72%, respectively. The total NPK losses (sediments and runoff) from BS averaged 0.87, 0.07 and 0.72 kg ha(-1), from CT 1.82, 0.11 and 0.97 kg ha(-1) and from NT 3.15, 0.29 and 2.45 kg ha(-1), respectively. In addition, nutrient concentrations in the surface runoff were higher than the recommended level for standard water quality for N-NO(3), N-NH(4) and soluble P, particularly from NT and CT. These results support the recommendation of non-tillage with barley strips for sloped agricultural land in order to reduce erosion and pollution.

  11. Modelling the surface deposition of meteoric smoke particles

    NASA Astrophysics Data System (ADS)

    Brooke, James S. A.; Feng, Wuhu; Mann, Graham W.; Dhomse, Sandip S.; Bardeen, Charles G.; Plane, John M. C.

    2016-04-01

    The flux of meteoric smoke particles (MSPs) in Greenland and Antarctica has been measured using Ir and Pt observations in ice cores, by Gabrielli et al. [1,2]. They obtained MSP deposition fluxes of 1.5 ± 0.45 × 10-4 g m-2 yr-1 (209 ± 63 t d-1) in Greenland and 3.9 ± 1.4 × 10-5 g m-2 yr-1 (55 ± 19 t d-1) in Antarctica, where the values in parentheses are total atmospheric inputs, assuming a uniform global deposition rate. These results show reasonable agreement with those of Lanci et al. [3], who used ice core magnetisation measurements, resulting in MSP fluxes of 1.7 ± 0.23 × 10-4 g m-2 yr-1 (236 ± 50 t d-1) (Greenland) and 2.0 ± 0.52 × 10-5 g m-2 yr-1 (29 ± 5.0 t d-1) (Antarctica). Atmospheric modelling studies have been performed to assess the transport and deposition of MSPs, using WACCM (Whole Atmosphere Community Climate Model), and the CARMA (Community Aerosol and Radiation Model) aerosol microphysics package. An MSP input function totalling 44 t d-1 was added between about 80 and 105 km. Several model runs have been performed in which the aerosol scavenging by precipitation was varied. Wet deposition is expected (and calculated here) to be the main deposition process; however, rain and snow aerosol scavenging coefficients have uncertainties spanning up to two and three orders of magnitude, respectively [4]. The model experiments that we have carried out include simple adjustments of the scavenging coefficients, full inclusion of a parametrisation reported by Wang et al. [4], and a scheme based on aerosol removal where relative humidity > 100 %. The MSP fluxes obtained vary between 1.4 × 10-5 and 2.6 × 10-5 g m-2 yr-1 for Greenland, and 5.1 × 10-6 and 1.7 × 10-5 g m-2 yr-1 for Antarctica. These values are about an order of magnitude lower than the Greenland observations, but show reasonable agreement for Antarctica. The UM (Unified Model), UKCA (United Kingdom Chemistry and Aerosols Model), and GLOMAP (GLObal Model of Aerosol Processes) have

  12. Probing the mass-loss history of AGB and red supergiant stars from CO rotational line profiles. II. CO line survey of evolved stars: derivation of mass-loss rate formulae

    NASA Astrophysics Data System (ADS)

    De Beck, E.; Decin, L.; de Koter, A.; Justtanont, K.; Verhoelst, T.; Kemper, F.; Menten, K. M.

    2010-11-01

    Context. The evolution of intermediate and low-mass stars on the asymptotic giant branch is dominated by their strong dust-driven winds. More massive stars evolve into red supergiants with a similar envelope structure and strong wind. These stellar winds are a prime source for the chemical enrichment of the interstellar medium. Aims: We aim to (1) set up simple and general analytical expressions to estimate mass-loss rates of evolved stars, and (2) from those calculate estimates for the mass-loss rates of the asymptotic giant branch, red supergiant, and yellow hypergiant stars in our galactic sample. Methods: The rotationally excited lines of carbon monoxide (CO) are a classic and very robust diagnostic in the study of circumstellar envelopes. When sampling different layers of the circumstellar envelope, observations of these molecular lines lead to detailed profiles of kinetic temperature, expansion velocity, and density. A state-of-the-art, nonlocal thermal equilibrium, and co-moving frame radiative transfer code that predicts CO line intensities in the circumstellar envelopes of late-type stars is used in deriving relations between stellar and molecular-line parameters, on the one hand, and mass-loss rate, on the other. These expressions are applied to our extensive CO data set to estimate the mass-loss rates of 47 sample stars. Results: We present analytical expressions for estimating the mass-loss rates of evolved stellar objects for 8 rotational transitions of the CO molecule and thencompare our results to those of previous studies. Our expressions account for line saturation and resolving of the envelope, thereby allowing accurate determination of very high mass-loss rates. We argue that, for estimates based on a single rotational line, the CO(2-1) transition provides the most reliable mass-loss rate. The mass-loss rates calculated for the asympotic giant branch stars range from 4 × 10-8 M⊙ yr-1 up to 8 × 10-5 M⊙ yr-1. For red supergiants they reach

  13. Reprint of: Multiwavelength modeling the SED of supersoft X-ray sources III. RS Ophiuchi: The supersoft X-ray phase and beyond

    NASA Astrophysics Data System (ADS)

    Skopal, A.

    2015-04-01

    I modeled the 14 Å-37 μ m SED of the recurrent symbiotic nova RS Oph during its supersoft source (SSS) phase and the following quiescent phase. During the SSS phase, the model SEDs revealed the presence of a strong stellar and nebular component of radiation in the spectrum. The former was emitted by the burning WD at highly super-Eddington rate, while the latter represented a fraction of its radiation reprocessed by the thermal nebula. During the transition phase, both the components were decreasing and during quiescence the SED satisfied radiation produced by a large, optically thick disk (Rdisk > 10 R⊙). The super-Eddington luminosity of the burning WD during the SSS phase was independently justified by the high quantity of the nebular emission. The emitting material surrounded the burning WD, and its mass was (1.6 ± 0.5) ×10-4(d / 1.6kpc) 5 / 2 M⊙ . The helium ash, deposited on the WD surface during the whole burning period, was around of 8 ×10-6(d / 1.6kpc) 2 M⊙ , which yields an average growing rate of the WD mass, M˙WD ∼ 4 ×10-7(d / 1.6kpc) 2 M⊙yr-1 . The mass accreted by the WD between outbursts, macc ∼ 1.26 ×10-5 M⊙ , constrains the average accretion rate, M˙acc ∼ 6.3 ×10-7 M⊙yr-1 . During quiescence, the accretion rate from the model SED of ∼ 2.3 ×10-7 M⊙yr-1 requires a super-Eddington accretion from the disk at ∼ 3.6 ×10-5 M⊙yr-1 during the outburst. Such a high accretion can be responsible for the super-Eddington luminosity during the whole burning phase. Simultaneous presence of jets supports this scenario. If the wind from the giant is not sufficient to feed the WD at the required rate, the accretion can be realized from the disk-like reservoir of material around the WD. In this case the time between outbursts will extend, with the next explosion beyond 2027. In the opposite case, the wind from the giant has to be focused to the orbital plane to sustain the high accretion rate at a few ×10-7 M⊙yr-1 . Then the

  14. Maximally Star-forming Galactic Disks. I. Starburst Regulation Via Feedback-driven Turbulence

    NASA Astrophysics Data System (ADS)

    Ostriker, Eve C.; Shetty, Rahul

    2011-04-01

    Star formation rates in the centers of disk galaxies often vastly exceed those at larger radii, whether measured by the surface density of star formation ΣSFR, by the star formation rate per unit gas mass, ΣSFR/Σ, or even by total output. In this paper, we investigate the idea that central starbursts are self-regulated systems in which the momentum flux injected to the interstellar medium (ISM) by star formation balances the gravitational force confining the ISM gas in the disk. For most starbursts, supernovae are the largest contributor to the momentum flux, and turbulence provides the main pressure support for the predominantly molecular ISM. If the momentum feedback per stellar mass formed is p*/m* ~ 3000 km s-1, the predicted star formation rate is ΣSFR ~ 2πGΣ2 m*/p* ~ 0.1 Msun kpc-2 yr-1(Σ/100 Msun pc-2)2 in regions where gas dominates the vertical gravity. We compare this prediction with numerical simulations of vertically resolved disks that model star formation including feedback, finding good agreement for gas surface densities in the range Σ ~ 102-103 Msun pc-2. We also compare to a compilation of star formation rates and gas contents from local and high-redshift galaxies (both mergers and normal galaxies), finding good agreement provided that the conversion factor X CO from integrated CO emission to H2 surface density decreases modestly as Σ and ΣSFR increase. Star formation rates in dense, turbulent gas are also expected to depend on the gravitational free-fall time at the corresponding mean ISM density ρ0 if the star formation efficiency per free-fall time is ɛff(ρ0) ~ 0.01, the turbulent velocity dispersion driven by feedback is expected to be vz = 0.4 ɛff(ρ0)p*/m* ~ 10 km s-1, relatively independent of Σ or ΣSFR. Turbulence-regulated starbursts (controlled by kinetic momentum feedback) are part of the larger scheme of self-regulation; primarily atomic low-Σ outer disks may have star formation regulated by ultraviolet heating

  15. Sulfur and nitrogen emissions in the Czech Republic and Slovakia from 1850 till 2000

    NASA Astrophysics Data System (ADS)

    Kopáček, Jiří; Veselý, Josef

    The respective rates of SO 2, NO x, and NH 3 anthropogenic emissions in the former Czechoslovakia (the Czech Republic and Slovakia (CS)) were <10, <5, and 33 mmol m -2 yr -1 in 1850, increased slowly until 1950 and rapidly in the 1950-1980 period, and peaked at ˜380, ˜180 and ˜80 mmol m -2 yr -1 in the 1980s. The emissions declined markedly after the political and economical changes in 1989 due to (1) restructuring of industry and farming in the early 1990s (˜35% decrease in energy production and 50-60% decrease in cattle numbers and fertilization rate of farmland), (2) sulfur emission controls, (3) changes in fuel supply, and (4) optimization of combustion regimes at stationary sources of NO x. The CS emission rates of SO 2, NO x, and NH 3 were 87%, 51%, and ˜44% lower, respectively, in 2000 than in 1985. Emissions of SO 2 declined linearly throughout the 1990s (to 47 mmol m -2 yr -1 in 2000), while NO x and NH 3 emissions declined rapidly during 1989-1994 and then slowly to ˜85 and ˜44 mmol m -2 yr -1, respectively, in 2000. Similar declines in SO 2 and NO x emissions occurred in the entire central European region, while NH 3 emission decreased less over a wider region due predominantly to more stable emission rates of NH 3 in Germany. Emission rates of S and N compounds correlated tightly ( P<0.001) with their deposition in the CS region.

  16. Volatile snowlines in embedded disks around low-mass protostars

    NASA Astrophysics Data System (ADS)

    Harsono, D.; Bruderer, S.; van Dishoeck, E. F.

    2015-10-01

    Context. Models of the young solar nebula assume a hot initial disk in which most volatiles are in the gas phase. Water emission arising from within 50 AU radius has been detected around low-mass embedded young stellar objects. The question remains whether an actively accreting disk is warm enough to have gas-phase water up to 50 AU radius. No detailed studies have yet been performed on the extent of snowlines in an accreting disk embedded in a dense envelope (stage 0). Aims: We aim to quantify the location of gas-phase volatiles in the inner envelope and disk system for an actively accreting embedded disk. Methods: Two-dimensional physical and radiative transfer models were used to calculate the temperature structure of embedded protostellar systems. Heating due to viscous accretion was added through the diffusion approximation. Gas and ice abundances of H2O, CO2, and CO were calculated using the density-dependent thermal desorption formulation. Results: The midplane water snowline increases from 3 to ~55 AU for accretion rates through the disk onto the star between 10-9-10-4M⊙ yr-1. CO2 can remain in the solid phase within the disk for Ṁ ≤ 10-5M⊙ yr-1 down to ~20 AU. Most of the CO is in the gas phase within an actively accreting disk independent of disk properties and accretion rate. The predicted optically thin water isotopolog emission is consistent with the detected H218O emission toward the stage 0 embedded young stellar objects, originating from both the disk and the warm inner envelope (hot core). An accreting embedded disk can only account for water emission arising from R< 50 AU, however, and the extent rapidly decreases for Ṁ ≤ 10-5M⊙ yr-1. Thus, the radial extent of the emission can be measured with future ALMA observations and compared to this 50 AU limit. Conclusions: Volatiles such as H2O, CO2, CO, and the associated complex organics sublimate out to 50 AU in the midplane of young disks and, thus, can reset the chemical content

  17. The Biogeochemical Role of Antarctic Krill and Baleen Whales in Southern Ocean Nutrient Cycling.

    NASA Astrophysics Data System (ADS)

    Ratnarajah, L.

    2015-12-01

    Iron limits primary productivity in large areas of the Southern Ocean. It has been suggested that baleen whales form a crucial part of biogeochemical cycling processes through the consumption of nutrient-rich krill and subsequent defecation, but evidence on their contribution is scarce. We analysed the concentration of iron in Antarctic krill and baleen whale faeces and muscle. Iron concentrations in Antarctic krill were over 1 million times higher, and whale faecal matter were almost 10 million times higher than typical Southern Ocean High Nutrient Low Chlorophyll seawater concentrations. This suggests that Antarctic krill act as a reservoir of in in Southern Ocean surface waters, and that baleen whales play an important role in converting this fixed iron into a liquid form in their faeces. We developed an exploratory model to examine potential contribution of blue, fin and humpback whales to the Southern Ocean iron cycle to explore the effect of the recovery of great whales to historical levels. Our results suggest that pre-exploitation populations of blue whales and, to a lesser extent fin and humpback whales, could have contributed to the more effective recycling of iron in surface waters, resulting in enhanced phytoplankton production. This enhanced primary productivity is estimated to be: 8.3 x 10-5 to 15 g C m-2 yr-1 (blue whales), 7 x 10-5 to 9 g C m-2 yr-1 (fin whales), and 10-5 to 1.7 g C m-2 yr-1 (humpback whales). To put these into perspective, current estimates of primary production in the Southern Ocean from remotely sensed ocean colour are in the order of 57 g C m-2 yr-1 (south of 50°). The high degree of uncertainty around the magnitude of these increases in primary productivity is mainly due to our limited quantitative understanding of key biogeochemical processes including iron content in krill, krill consumption rates by whales, persistence of iron in the photic zone, bioavailability of retained iron, and carbon-to-iron ratio of phytoplankton

  18. A model for the strings of η Carinae

    NASA Astrophysics Data System (ADS)

    Soker, N.

    2001-10-01

    We propose a model based on ionization shadows to explain the formation of the long and narrow strings of eta Carinae. Five strings are known, all located along the symmetry axis outside the Homunculus. The model assumes that each string is formed in a shadow behind a dense clump near the symmetry axis. The surrounding gas is ionized first, becomes much hotter, and compresses the gas in the shadow. This leads to the formation of a radial, dense, long, and narrow region, i.e., a string. Later the neutral material in the strings is ionized, and becomes brighter. Still later it re-expands, and we predict that in ~100-200 yrs the strings will fade. The condition for the model to work is that the ionization front, due to the diffuse ionizing recombination radiation of the surrounding gas, proceeds into the shadow at a velocity slower than the compression speed, which is about the sound speed. From that we get a condition on the mass loss rate of the mass loss episode that formed the strings, which reads dot Ms <~ 10-4 Msun yr-1. The model can also explain the strings in the planetary nebula NGC 6543.

  19. Abiotic racemization kinetics of amino acids in marine sediments.

    PubMed

    Steen, Andrew D; Jørgensen, Bo Barker; Lomstein, Bente Aa

    2013-01-01

    The ratios of d- versus l-amino acids can be used to infer the sources and composition of sedimentary organic matter. Such inferences, however, rely on knowing the rates at which amino acids in sedimentary organic matter racemize abiotically between the d- and the l-forms. Based on a heating experiment, we report kinetic parameters for racemization of aspartic acid, glutamic acid, serine, and alanine in bulk sediment from Aarhus Bay, Denmark, taken from the surface, 30 cm, and 340 cm depth below seafloor. Extrapolation to a typical cold deep sea sediment temperature of 3°C suggests racemization rate constants of 0.50×10(-5)-11×10(-5) yr(-1). These results can be used in conjunction with measurements of sediment age to predict the ratio of d:l amino acids due solely to abiotic racemization of the source material, deviations from which can indicate the abundance and turnover of active microbial populations.

  20. Gas Poor Galaxies in MKW/AWM Clusters

    NASA Astrophysics Data System (ADS)

    Williams, B. A.

    1995-03-01

    Follow-up observations were made of the neutral hydrogen content of 129 galaxies near the cores of MKW 4, MKW 8, MKW 11, AWM 4, and AWM 5. The neutral hydrogen content of these galaxies appears to be lower than that of galaxies of similar type in the field or in loose groups and are more consistent with those of galaxies in the richer Abell clusters. Of the 14 galaxies that appear to be spirals in MKW 4, only one was detected above a sensitivity limit of ~ 10(5) Msun /Mpc(2) . The low detection rate of galaxies in MKW 4 suggest that its core is truly deficient in neutral hydrogen gas.

  1. Determination of atmospheric nitrogen deposition to a semi-natural peat bog site in an intensively managed agricultural landscape

    NASA Astrophysics Data System (ADS)

    Hurkuck, Miriam; Brümmer, Christian; Mohr, Karsten; Grünhage, Ludger; Flessa, Heinz; Kutsch, Werner L.

    2014-11-01

    Rising levels of atmospheric nitrogen (N) deposition have been found to affect the primary productivity and species composition of most terrestrial ecosystems. Highly vulnerable ecosystems such as nutrient-poor bogs are expected to respond to increasing N input rates with a decrease in plant species diversity. Our study site - a moderately drained raised bog and one of only very few remaining protected peatland areas in Northwestern Germany - is surrounded by highly fertilised agricultural land and intensive livestock production. We quantified the annual deposition of atmospheric N over a period of two years. Dry deposition rates of different N species and their reactants were calculated from day and night-time concentrations measured by a KAPS denuder filter system. Dry N deposition amounted to 10.9 ± 1.0 kg N ha-1 yr-1 (year 1) and 10.5 ± 1.0 kg N ha-1 yr-1 (year 2). More than 80% of total deposited N was attributed to ammonia (NH3). A strong seasonality in NH3 concentrations and depositions could be observed. Day and night-time concentrations and depositions, however, did not differ significantly. Total N deposition including bulk N deposition resulted in about 25 kg N ha-1 yr-1. Our results suggest that the intensive agricultural land management of surrounding areas and strongly emitting animal husbandry lead to N inputs into the protected peatland area that exceed the ecosystem's specific critical load up to fivefold. This gives rise to the assumption that a further shift in plant species composition with a subsequent alteration of the local hydrological regime can be expected.

  2. Deposition and leaching of sulfur, nitrogen and calcium in four forested catchments in China: implications for acidification.

    PubMed

    Larssen, Thorjørn; Duan, Lei; Mulder, Jan

    2011-02-15

    Here we present the first detailed study on fluxes of sulfur (S), nitrogen (N), and major cations in Chinese subtropical forest catchments. Data are from four study sites, differing in inputs of atmospheric pollutants and sensitivity to acidification. Results show important differences from most sites in North America and Europe. Dry deposition of S, N, and calcium (Ca) is considerably larger than wet deposition in most cases causing deposition fluxes ranging from moderate to very high, both for acidifying compounds (S deposition 1.5-10.5 kiloequivalents per hectare and year (keq ha(-1) yr(-1)); N deposition 0.4 to 2.5 keq ha(-1) yr(-1)) and for alkaline compounds (Ca deposition 0.8 to 5.7 keq ha(-1) yr(-1)). More than half of the input of acidity is neutralized by alkalinity associated with Ca deposition. Furthermore, the retention of incoming S and N is small in the soil root zone, but considerable in the deeper soils or riparian zone. Drainage water from the root zone of the soils at the two sites with the highest deposition show pronounced acidification. For the two sites with moderate deposition inputs, the root zones are retaining some of the incoming S and buffer some of the incoming acidity. The subsoils and the riparian zonesare strong sinks for N, S, and Ca. This is associated with substantial acid neutralization at all sites. These features are of major importance for the understanding of the long-term effects of acidification in China. PMID:21250675

  3. Spectral Energy Distribution Analysis of Class I and Class II FU Orionis Stars

    NASA Astrophysics Data System (ADS)

    Gramajo, Luciana V.; Rodón, Javier A.; Gómez, Mercedes

    2014-06-01

    FU Orionis stars (FUors) are eruptive pre-main sequence objects thought to represent quasi-periodic or recurring stages of enhanced accretion during the low-mass star-forming process. We characterize the sample of known and candidate FUors in a homogeneous and consistent way, deriving stellar and circumstellar parameters for each object. We emphasize the analysis in those parameters that are supposed to vary during the FUor stage. We modeled the spectral energy distributions of 24 of the 26 currently known FUors, using the radiative transfer code of Whitney et al. We compare our models with those obtained by Robitaille et al. for Taurus class II and I sources in quiescence periods by calculating the cumulative distribution of the different parameters. FUors have more massive disks: we find that ~80% of the disks in FUors are more massive than any Taurus class II and I sources in the sample. Median values for the disk mass accretion rates are ~10-7 M ⊙ yr-1 versus ~10-5 M ⊙ yr-1 for standard young stellar objects (YSOs) and FUors, respectively. While the distributions of envelope mass accretion rates for class I FUors and standard class I objects are similar, FUors, on average, have higher envelope mass accretion rates than standard class II and class I sources. Most FUors (~70%) have envelope mass accretion rates above 10-7 M ⊙ yr-1. In contrast, 60% of the classical YSO sample has an accretion rate below this value. Our results support the current scenario in which changes experimented by the circumstellar disk explain the observed properties of these stars. However, the increase in the disk mass accretion rate is smaller than theoretically predicted, although in good agreement with previous determinations.

  4. CO J = 2-1 and 4-3 Observations of Proto-planetary Nebulae: Time-variable Mass Loss

    NASA Astrophysics Data System (ADS)

    Hrivnak, Bruce J.; Bieging, John H.

    2005-05-01

    Observations made with the Heinrich Hertz Telescope of CO millimeter and submillimeter emission toward a sample of 22 proto-planetary nebula (PPN) candidates resulted in detections of 12 sources in the CO J=2-1 line. Of these 12, seven sources were also detected in the J=4-3 line. These 4-3 transitions are the highest yet observed in all but one of these PPNs. Statistical equilibrium/radiative transfer models were calculated for the CO emission in the circumstellar envelopes (CSEs), assuming various power-law density distributions. These models were compared with the intensity and profile shape of the observed spectra. For the region of the CSE probed by CO emission, the density laws must be steeper than inverse squared and are consistent with power laws between ρ~r-3 and r-4. These radial density distributions imply that the mass loss was not constant but increased during the last part of the asymptotic giant branch (AGB) phase. Mass-loss rates at the end of the AGB for the three best-constrained sources are found to be 7.7×10-5 Msolar yr-1 (IRAS 22272+5435), 2.3×10-5 Msolar yr-1 (IRAS 07134+1005), and 1.3×10-5 Msolar yr-1 (IRAS 17436+5003) for the case of ρ~r-3. These time-varying mass-loss rates can be integrated to calculate the enclosed envelope masses ejected in the past ~10,000 yr. The ejected envelope masses close to the star lie in the range 0.02-0.30 Msolar these values are consistent with theoretical models, which indicate that <20% of the stellar mass loss occurs in the last 10,000 years of the AGB. These results are in contrast to some recent dust studies based on infrared emission, however, in which much higher envelope masses are determined. The density laws, mass-loss rates, and enclosed envelope masses that we derive furnish important constraints for evolutionary models of stars in the late AGB and during the transition to the planetary nebula phase.

  5. Atmospheric particle characterization, distribution, and deposition in Xi'an, Shaanxi Province, Central China.

    PubMed

    Cao, Zongze; Yang, Yuhua; Lu, Julia; Zhang, Chengxiao

    2011-02-01

    Physical characterization and chemical analysis of settled dusts collected in Xi'an from November 2007 to December 2008 show that (1) dust deposition rates ranged from 14.6 to 350.4 g m(-2) yr(-1). The average deposition rate (76.7 g m(-2) yr(-1)) ranks the 11th out of 56 dust deposition rates observed throughout the world. The coal-burning power was the major particle source; (2) on average (except site 4), ∼10% of the settled dusts having size <2.6, ∼30% having size <10.5, and >70% having size <30 μm; (3) the concentrations for 20 out of 27 elements analyzed were upto 18 times higher than their soil background values in China. With such high deposition rates of dusts that contain elevated levels of toxic elements, actions should be taken to reduce emission and studies are needed to assess the potential impacts of settled particles on surface ecosystem, water resource, and human health in the area.

  6. Interprovincial Reliance for Improving Air Quality in China: A Case Study on Black Carbon Aerosol.

    PubMed

    Li, Yun; Meng, Jing; Liu, Junfeng; Xu, Yuan; Guan, Dabo; Tao, Wei; Huang, Ye; Tao, Shu

    2016-04-01

    Black carbon (BC) is of global concern because of its adverse effects on climate and human health. It can travel long distances via atmospheric movement and can be geographically relocated through trade. Here, we explored the integrated patterns of BC transport within 30 provinces in China from the perspective of meteorology and interprovincial trade using the Weather Research and Forecasting with Chemistry (WRF/Chem) model and multiregional input-output analysis. In general, cross-border BC transport, which accounts for more than 30% of the surface concentration, occurs mainly between neighboring provinces. Specifically, Hebei contributes 1.2 μg·m(-3) BC concentration in Tianjin. By contrast, trade typically drives virtual BC flows from developed provinces to heavily industrial provinces, with the largest net flow from Beijing to Hebei (4.2 Gg). Shanghai is most vulnerable to domestic consumption with an average interprovincial consumption influence efficiency of 1.5 × 10(-4) (μg·m(-3))/(billion Yuan·yr(-1)). High efficiencies (∼8 × 10(-5) (μg·m(-3))/(billion Yuan·yr(-1))) are also found from regions including Beijing, Jiangsu, and Shanghai to regions including Hebei, Shandong, and Henan. The above source-receptor relationship indicates two control zones: Huabei and Huadong. Both mitigating end-of-pipe emissions and rationalizing the demand for pollution-intense products are important within the two control zones to reduce BC and other pollutants. PMID:26950657

  7. Young, Star-forming Galaxies and Their Local Counterparts: The Evolving Relationship of Mass-SFR-Metallicity Since z ˜ 2.1

    NASA Astrophysics Data System (ADS)

    Grasshorn Gebhardt, Henry S.; Zeimann, Gregory R.; Ciardullo, Robin; Gronwall, Caryl; Hagen, Alex; Bridge, Joanna S.; Schneider, Donald P.; Trump, Jonathan R.

    2016-01-01

    We explore the evolution of the Stellar Mass-Star Formation Rate (SFR)-Metallicity relation using a set of 256 COSMOS and GOODS galaxies in the redshift range 1.90 < z < 2.35. We present the galaxies’ rest-frame optical emission-line fluxes derived from IR-grism spectroscopy with the Hubble Space Telescope and combine these data with SFRs and stellar masses obtained from deep, multi-wavelength (rest-frame UV to IR) photometry. We then compare these measurements to those for a local sample of galaxies carefully matched in stellar mass (7.5≲ {log}({M}*/{M}⊙ )≲ 10.5) and SFR (-0.5≲ {log}({{SFR}})≲ 2.5 in M⊙ yr-1). We find that the distribution of z ˜ 2.1 galaxies in stellar mass-SFR-metallicity space is clearly different from that derived for our sample of similarly bright ({L}{{H}β }\\gt 3× {10}40 erg s-1) local galaxies, and this offset cannot be explained by simple systematic offsets in the derived quantities. At stellar masses above ˜ {10}9 {M}⊙ and SFRs above ˜ 10 {M}⊙ yr-1, the z ˜ 2.1 galaxies have higher oxygen abundances than their local counterparts, while the opposite is true for lower-mass, lower-SFR systems.

  8. The rate of Type Ia supernovae at z ~ 0.2 from SDSS-I overlapping fields

    NASA Astrophysics Data System (ADS)

    Horesh, A.; Poznanski, D.; Ofek, E. O.; Maoz, D.

    2008-10-01

    In the course of the Sloan Digital Sky Survey (SDSS-I), a large fraction of the surveyed area was observed more than once due to field tiling overlap, usually at different epochs. We utilize some of these data to perform a supernova (SN) survey at a mean redshift of z = 0.2. Our archival search, in ~5 per cent of the SDSS-I overlap area, produces 29 SN candidates clearly associated with host galaxies. Using the Bayesian photometric classification algorithm of Poznanski et al., and correcting for classification bias, we find 17 of the 29 candidates are likely Type Ia SNe. Accounting for the detection efficiency of the survey and for host extinction, this implies a Type Ia SN rate of rIa = (14.0+2.5+1.4-2.5-1.1 +/- 2.5) × 10-14h270yr-1L-1solar,g, where the errors are Poisson error, systematic detection efficiency error and systematic classification error, respectively. The volumetric rate is RIa = (1.89+0.42+0.18-0.34-0.15 +/- 0.42) × 10-5yr-1h370Mpc-3. Our measurement is consistent with other rate measurements at low redshift. An order of magnitude increase in the number of SNe is possible by analysing the full SDSS-I data base.

  9. Physical Properties of Emission-Line Galaxies at 2 from Near-Infrared Spectroscopy with Magellan FIRE

    NASA Astrophysics Data System (ADS)

    Masters, Daniel C.; McCarthy, P. J.; Malkan, M. A.; Siana, B. D.; Scarlata, C.; Hathi, N. P.; Atek, H.; Henry, A. L.; WISP Team

    2014-01-01

    We present results from near-infrared spectroscopy with Magellan FIRE of 26 strong emission-line galaxies at 2.2 and 1.5. The sample was selected from the WFC3 Infrared Spectroscopic Parallels (WISP) survey, which uses the near-infrared grism capability of the Hubble Space Telescope Wide Field Camera 3 to detect emission-line galaxies over 0.5 < z < 2.3. High-resolution ( 5000) follow-up spectroscopy with Magellan FIRE over 1.0--2.5 microns resolves important rest-frame optical emission lines, allowing us to measure physical properties such as dust obscuration, metal abundance, star formation rate, ionization parameter, and emission line kinematics. We also analyze the properties of composite spectra derived from the FIRE-observed sample. With this relatively large sample of rest-frame optical spectra we can make statistical inferences about the population of emission-line galaxies at 2. We find that the galaxies are low metallicity ( 1/5-1/2 Z_solar) as determined from the R23 calibration. The galaxies are low dust extinction on average (E(B-V 0.2) but with significant scatter. The dust-corrected H-alpha star formation rates range from ~10--150 M_sun yr^-1 with a mean of 50 M_su yr^-1. The average ionization parameter for the sample, log U ~ -2.5, is higher than typically found for star-forming galaxies in the local universe but consistent with those found in more intense starbursting regions in galaxies such as M82. Emission line velocity dispersions are measured to be 71 +- 38 km s^-1, in good agreement with other studies that have probed the H-alpha kinematics of star-forming galaxies at similar redshift. The galaxies are compact, with half-light radii of < 2 kpc, and ~50% show evidence for multiple structures or asymmetries in the WFC3 imaging. Based on the line velocity dispersions and the location of the galaxies on BPT diagnostic plots, there is little evidence for significant AGN contribution to most emission-line galaxies at 2.

  10. Wet and dry deposition of mineral dust particles in Japan: factors related to temporal variation and spatial distribution

    NASA Astrophysics Data System (ADS)

    Osada, K.; Ura, S.; Kagawa, M.; Mikami, M.; Tanaka, T. Y.; Matoba, S.; Aoki, K.; Shinoda, M.; Kurosaki, Y.; Hayashi, M.; Shimizu, A.; Uematsu, M.

    2013-08-01

    Data of temporal variations and spatial distributions of mineral dust deposition fluxes are very limited in terms of duration, location, and processes of deposition. To ascertain temporal variations and spatial distributions of mineral dust deposition by wet and dry processes, weekly deposition samples were obtained at Sapporo, Toyama, Nagoya, Tottori, Fukuoka, and Cape Hedo (Okinawa) in Japan during October 2008-December 2010 using automatic wet and dry separating samplers. Mineral dust weights in water-insoluble residue were estimated from Fe contents measured using an X-ray fluorescence analyzer. For wet deposition, highest and lowest annual dust fluxes were found at Toyama (9.6 g m-2 yr-1) and at Cape Hedo (1.7 g m-2 yr-1) as average values in 2009 and 2010. Higher wet deposition fluxes were observed at Toyama and Tottori, where frequent precipitation (>60% days per month) was observed during dusty seasons. For dry deposition among Toyama, Tottori, Fukuoka, and Cape Hedo, the highest and lowest annual dust fluxes were found respectively at Fukuoka (5.2 g m-2 yr-1) and at Cape Hedo (2.0 g m-2 yr-1) as average values in 2009 and 2010. Although the seasonal tendency of the monthly dry deposition amount roughly resembled that of monthly days of Kosa dust events, the monthly amount of dry deposition was not proportional to monthly days of the events. Comparison of dry deposition fluxes with vertical distribution of dust particles deduced from Lidar data and coarse particle concentrations suggested that the maximum dust layer height or thickness is an important factor for controlling the dry deposition amount after long-range transport of dust particles. Size distributions of refractory dust particles were obtained using four-stage filtration: >20, >10, >5, and >1 μm diameter. Weight fractions of the sum of >20 μm and 10-20 μm (giant fraction) were higher than 50% for most of the event samples. Irrespective of the deposition type, the giant dust fractions were

  11. Limits on the time variation of the electromagnetic fine-structure constant in the low energy limit from absorption lines in the spectra of distant quasars.

    PubMed

    Srianand, R; Chand, H; Petitjean, P; Aracil, B

    2004-03-26

    We present the results of a detailed many-multiplet analysis performed on a new sample of Mg ii systems observed in high quality quasar spectra obtained using the Very Large Telescope. The weighted mean value of the variation in alpha derived from our analysis over the redshift range 0.410(-5). The median redshift of our sample (z approximately 1.55) corresponds to a look-back time of 9.7 Gyr in the most favored cosmological model today. This gives a 3sigma limit, -2.5 x 10(-16)yr(-1), for the time variation of alpha, that forms the strongest constraint obtained based on high redshift quasar absorption line systems.

  12. Modeling the Infrared Emission from Cygnus A

    NASA Astrophysics Data System (ADS)

    Privon, George C.; Baum, S.; O'Dea, C.; Axon, D.; Robinson, A.; Gallimore, J.; Noel-Storr, J.

    2010-01-01

    The Spitzer Space Telescope provides a unique view of the Universe at infrared wavelengths. Improved sensitivity and angular resolution over previous missions enable detailed studies of astrophysical objects, both in imaging and spectroscopic modes. Spitzer observations of active galactic nuclei can help shed light on the physical conditions of the central regions of these active galaxies. The nearby radio galaxy Cygnus A is one of the most luminous radio sources in the local Universe. In addition to the high radio power, it is also very luminous in the infrared. New Spitzer spectroscopy and photometry of Cygnus A is combined with data from the literature at radio and sub-mm wavelengths. The resulting complication is modeled with a combination of: a synchrotron emitting jet, a burst of star formation, and emission from an AGN torus. The infrared emission in Cyngus A shows contributions from all three processes and the models are able to reproduce the observed emission over almost 5 dex in frequency. The bolometric AGN luminosity is found to be 1045 erg s-1, with a clumpy torus size of 7 pc. Evidence is seen for a break in the synchrotron spectrum in the mid-infrared. The relevant component of the infrared emission suggests Cygnus A has a star formation rate of 20 Msun yr-1. Even in the absence of the AGN, it would still be a luminous infrared source. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech.

  13. Light curve solution and orbital period analysis of the contact binary V842 Herculis

    NASA Astrophysics Data System (ADS)

    Selam, S. O.; Albayrak, B.; Şenavci, H. V.; Aksu, O.

    2005-10-01

    New photoelectric BV light curves were obtained for the neglected eclipsing binary V842 Her at the TÜB{İTAK National Observatory (TUG) and studied for the first time in detail to determine the orbital parameters and geometry of the system. The solutions obtained simultaneously for the new light curves and the radial velocity curves in the literature by using the Wilson-Devinney code reveal a typical W-type contact system. The light curves exhibit the so-called O'Connell effect which the level of the primary maxima being higher than that of the secondary ones in both pass-bands. The O'Connell effect in the light curves is explained in terms of a dark-spot located on the more massive component which makes the more massive larger component slightly cooler than the less massive smaller one. The O-C diagram constructed for all available times of minima of V842 Her exhibits a cyclic character superimposed on a quadratic variation. The quadratic character yields a orbital period increase with a rate of dP/dt=7.76×10-7 days yr-1 which can be attributed to the mass exchange/loss mechanism in the system. By assuming the presence of a gravitationally bound third body in the system, the analysis of the cyclic nature in the O-C diagram revealed a third body with mass of 0.4M\\sun orbiting around the eclipsing pair. The possibility of magnetic activity cycle effect as a cause for the observed cyclic variation in the O-C diagram was also discussed.

  14. Six months of multiwavelength follow-up of the tidal disruption candidate ASASSN-14li and implied TDE rates from ASAS-SN

    NASA Astrophysics Data System (ADS)

    Holoien, T. W.-S.; Kochanek, C. S.; Prieto, J. L.; Stanek, K. Z.; Dong, Subo; Shappee, B. J.; Grupe, D.; Brown, J. S.; Basu, U.; Beacom, J. F.; Bersier, D.; Brimacombe, J.; Danilet, A. B.; Falco, E.; Guo, Z.; Jose, J.; Herczeg, G. J.; Long, F.; Pojmanski, G.; Simonian, G. V.; Szczygieł, D. M.; Thompson, T. A.; Thorstensen, J. R.; Wagner, R. M.; Woźniak, P. R.

    2016-01-01

    We present ground-based and Swift photometric and spectroscopic observations of the candidate tidal disruption event (TDE) ASASSN-14li, found at the centre of PGC 043234 (d ≃ 90 Mpc) by the All-Sky Automated Survey for SuperNovae (ASAS-SN). The source had a peak bolometric luminosity of L ≃ 1044 erg s-1 and a total integrated energy of E ≃ 7 × 1050 erg radiated over the ˜6 months of observations presented. The UV/optical emission of the source is well fitted by a blackbody with roughly constant temperature of T ˜ 35 000 K, while the luminosity declines by roughly a factor of 16 over this time. The optical/UV luminosity decline is broadly consistent with an exponential decline, L∝ e^{-t/t_0}, with t0 ≃ 60 d. ASASSN-14li also exhibits soft X-ray emission comparable in luminosity to the optical and UV emission but declining at a slower rate, and the X-ray emission now dominates. Spectra of the source show broad Balmer and helium lines in emission as well as strong blue continuum emission at all epochs. We use the discoveries of ASASSN-14li and ASASSN-14ae to estimate the TDE rate implied by ASAS-SN, finding an average rate of r ≃ 4.1 × 10-5 yr-1 per galaxy with a 90 per cent confidence interval of (2.2-17.0) × 10-5 yr-1 per galaxy. ASAS-SN found roughly 1 TDE for every 70 Type Ia supernovae in 2014, a rate that is much higher than that of other surveys.

  15. A Remodel of the Envelope around the 21 μm Protoplanetary Nebula IRAS 07134+1005

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Hui; Lee, Chin-Fei

    2012-01-01

    Recently, the CO J = 3-2 observational result of the envelope of the 21 μm protoplanetary nebula (PPN) IRAS 07134+1005 has been reported. Assuming that the CO J = 3-2 line was optically thin, the mass-loss rate of the superwind in this PPN was found to be at least 2 orders of magnitude lower than the typical range. In order to obtain a more accurate mass-loss rate, we reexamine these data and construct a radiative transfer model to compare with the data. Also, in order to better resolve the superwind, we adopt a different weighting on the data to obtain maps at a higher resolution. Our result shows that the CO J = 3-2 emission is located slightly further away from the central source than the mid-infrared emission, probably because the material is cooler on the outer part and is thus better traced by the CO emission. At a lower resolution, however, the CO emission appeared to be spatially coincident with the mid-IR emission. Our model has two components, an inner ellipsoidal shell-like superwind with an equatorial density enhancement and an outer spheroidal asymptotic giant branch wind. The thick torus in the previous model could be considered as the dense equatorial part of our ellipsoidal superwind. With radiative transfer, our model reproduces more observed features than the previous model, and it obtains an averaged superwind mass-loss rate of ~1.8 × 10-5 M ⊙ yr-1, which is typical for a superwind. The mass-loss rate in the equatorial plane is 3 × 10-5 M ⊙ yr-1, which is also the same as that derived before from modeling the CO J = 1-0 emission.

  16. Six months of multiwavelength follow-up of the tidal disruption candidate ASASSN-14li and implied TDE rates from ASAS-SN

    DOE PAGES

    Holoien, Thomas W. -S.; Kochanek, C. S.; Prieto, J. L.; Stanek, K. Z.; Dong, Subo; Shappee, B. J.; Grupe, D.; Brown, J. S.; Basu, U.; Beacom, J. F.; et al

    2015-11-25

    In this paper, we present ground-based and Swift photometric and spectroscopic observations of the candidate tidal disruption event (TDE) ASASSN-14li, found at the centre of PGC 043234 (d ≃ 90 Mpc) by the All-Sky Automated Survey for SuperNovae (ASAS-SN). The source had a peak bolometric luminosity of L ≃ 1044 erg s-1 and a total integrated energy of E ≃ 7 × 1050 erg radiated over the ~6 months of observations presented. The UV/optical emission of the source is well fitted by a blackbody with roughly constant temperature of T ~ 35 000 K, while the luminosity declines by roughlymore » a factor of 16 over this time. The optical/UV luminosity decline is broadly consistent with an exponential decline, L∝e-t/t0, with t0 ≃ 60 d. ASASSN-14li also exhibits soft X-ray emission comparable in luminosity to the optical and UV emission but declining at a slower rate, and the X-ray emission now dominates. Spectra of the source show broad Balmer and helium lines in emission as well as strong blue continuum emission at all epochs. Finally, we use the discoveries of ASASSN-14li and ASASSN-14ae to estimate the TDE rate implied by ASAS-SN, finding an average rate of r ≃ 4.1 × 10-5 yr-1 per galaxy with a 90 per cent confidence interval of (2.2–17.0) × 10-5 yr-1 per galaxy. ASAS-SN found roughly 1 TDE for every 70 Type Ia supernovae in 2014, a rate that is much higher than that of other surveys.« less

  17. Limits on variations in fundamental constants from 21-cm and ultraviolet Quasar absorption lines.

    PubMed

    Tzanavaris, P; Webb, J K; Murphy, M T; Flambaum, V V; Curran, S J

    2005-07-22

    Quasar absorption spectra at 21-cm and UV rest wavelengths are used to estimate the time variation of x [triple-bond] alpha(2)g(p)mu, where alpha is the fine structure constant, g(p) the proton g factor, and m(e)/m(p) [triple-bond] mu the electron/proton mass ratio. Over a redshift range 0.24 < or = zeta(abs) < or = 2.04, (Deltax/x)(weighted)(total) = (1.17 +/- 1.01) x 10(-5). A linear fit gives x/x = (-1.43 +/- 1.27) x 10(-15) yr(-1). Two previous results on varying alpha yield the strong limits Deltamu/mu = (2.31 +/- 1.03) x 10(-5) and Deltamu/mu=(1.29 +/- 1.01) x10(-5). Our sample, 8 x larger than any previous, provides the first direct estimate of the intrinsic 21-cm and UV velocity differences 6 km s(-1).

  18. Antagonism of lateral saphenous vein serotonin receptors from steers grazing endophyte-free, wild-type, or novel endophyte-infected tall fescue.

    PubMed

    Klotz, J L; Aiken, G E; Johnson, J M; Brown, K R; Bush, L P; Strickland, J R

    2013-09-01

    Pharmacologic profiling of serotonin (5HT) receptors of bovine lateral saphenous vein has shown that cattle grazing endophyte-infected (Neotyphodium coenophialum) tall fescue (Lolium arundinaceum) have altered responses to ergovaline, 5HT, 5HT2A, and 5HT7 agonists. To determine if 5HT receptor activity of tall fescue alkaloids is affected by grazing endophyte-free (EF), wild-type [Kentucky-31 (KY31)], novel endophyte AR542-infected (MAXQ), or novel endophyte AR584-infected (AR584) tall fescue, contractile responses of lateral saphenous veins biopsied from cattle grazing these different fescue-endophyte combinations were evaluated in presence or absence of antagonists for 5HT2A (ketanserin) or 5HT7 (SB-269970) receptors. Biopsies were conducted over 2 yr on 35 mixed-breed steers (361.5 ± 6.3 kg) grazing EF (n = 12), KY31 (n = 12), MAXQ (n = 6), or AR584 (n = 5) pasture treatments (3 ha) between 84 and 98 d (Yr 1) or 108 to 124 d (Yr 2). Segments (2 to 3 cm) of vein were surgically biopsied, sliced into 2- to 3-mm cross-sections, and suspended in a myograph chamber containing 5 mL of oxygenated Krebs-Henseleit buffer (95% O2/5% CO2; pH = 7.4; 37°C). Veins were exposed to increasing concentrations of 5HT, ergovaline, and ergovaline + 1 × 10(-5) M ketanserin or + 1 × 10(-6) M SB-269970 in Yr 1. In Yr 2, ergotamine and ergocornine were evaluated in presence or absence of 1 × 10(-5) M ketanserin. Contractile response data were normalized to a reference addition of 1 × 10(-4) M norepinephrine. In Yr 1, contractile response to 5HT and ergovaline were least (P < 0.05) in KY31 pastures and the presence of ketanserin greatly reduced (P < 0.05) the response to ergovaline in all pastures. However, presence of SB-269970 did not (P = 0.91) alter contractile response to ergovaline. In Yr 2, there was no difference in contractile response to ergotamine (P = 0.13) or ergocornine (P = 0.99) across pasture treatments, but ketanserin reduced (P < 0.05) the contractile response to

  19. WSRT HI imaging of ultra-compact high velocity clouds: gas-bearing dark matter minihalos?

    NASA Astrophysics Data System (ADS)

    Adams, Elizabeth A.; Oosterloo, Tom; Giovanelli, Riccardo; Haynes, Martha P.; Cannon, John M.; Faerman, Yakov; Janesh, William; Janowiecki, Steven; Munoz, Ricardo; Rhode, Katherine L.; Salzer, John Joseph; Sternberg, Amiel

    2015-01-01

    A long standing problem in cosmology is the mismatch between the number of low mass dark matter halos predicted by simulations and the number of low mass galaxies observed in the Local Volume. We recently presented a set of isolated ultra-compact high velocity clouds (UCHVCs) identified within the dataset of the Arecibo Legacy Fast ALFA (ALFALFA) HI line survey that are consistent with representing low-mass gas-bearing dark matter halos within the Local Volume (Adams+ 2013). At distances of ~1 Mpc, the UCHVCs have HI masses of ~10^5 Msun and indicative dynamical masses of 10^7-10^8 Msun. The HI diameters of the UCHVCs range from 4' to 20', or 1 to 6 kpc at a distance of 1 Mpc.We have selected the most compact and isolated UCHVCs with the highest average column densities as representing the best galaxy candidates. These systems have been observed with the Westerbork Synthesis Radio Telescope (WSRT) to enable higher spatial resolution (~60") studies of the HI distribution. The HI morphology revealed by the WSRT data offers clues to the environment and origin of the UCHVCs, the kinematics of the HI allow the underlying mass distribution to be constrained, and the combination of spatial and spectral resolution allow the detection of a cold neutral medium component to the HI. The WSRT HI observations discriminate among the selected galaxy candidates for those objects that are most likely gas-bearing dark matter halos.One UCHVC, AGC198606, is of particular interest as it is located 16 km/s and 1.2 degrees from Leo T and has similar HI properties within the ALFALFA dataset. The WSRT HI observations reveal a smooth HI morphology and a velocity gradient along the HI major axis of the system consistent with rotation. These properties are consistent with the hypothesis that this object is a gas-bearing low-mass dark matter halo.

  20. Mercury emissions to the atmosphere from natural and anthropogenic sources in the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Pirrone, N.; Costa, P.; Pacyna, J. M.; Ferrara, R.

    This report discusses past, current and projected mercury emissions to the atmosphere from major industrial sources, and presents a first assessment of the contribution to the regional mercury budget from selected natural sources. Emissions (1995 estimates) from fossil fuels combustion (29.8 t yr -1) , cement production (28.8 t yr -1) and incineration of solid wastes (27.6 t yr -1) , all together account for about 82% of the regional anthropogenic total (105.7 t yr -1) . Other industrial sources in the region are smelters (4.8 t yr -1) , iron-steel plants (4.8 t yr -1) and other minor sources (chlor-alkali plants, crematoria, chemicals production) that have been considered together in the miscellaneous category (9.6 t yr -1) . Regional emissions from anthropogenic sources increased at a rate of 3% yr-1 from 1983 to 1995 and are projected to increase at a rate of 1.9% yr-1 in the next 25 years, if no improvement in emission control policy occurs. On a country-by-country basis, France is the leading emitter country with 22.6 t yr -1 followed by Turkey (16.1 t yr -1) , Italy (11.4 t yr -1) , Spain (9.1 t yr -1) , the former Yugoslavia 7.9 ( t yr -1) , Morocco (6.9 t yr -1) , Bulgaria (6.8 t yr -1) , Egypt (6.1 t yr -1) , Syria (3.6 t yr -1) , Libya (2.9 t yr -1) , Tunisia (2.8 t yr -1) and Greece (2.7 t yr -1) , whereas the remaining countries account for less than 7% of the regional total. The annual emission from natural sources is 110 t yr -1, although this figure only includes the volatilisation of elemental mercury from surface waters and emissions from volcanoes, whereas the contribution due to the degassing of mercury from top soil and vegetation has not been included in this first assessment. Therefore, natural and anthropogenic sources in the Mediterranean region release annually about 215 t of mercury, which represents a significant contribution to the total mercury budget released in Europe and to the global atmosphere.

  1. NH4NO3 fertilizer induces DON leaching from Sphagnum magellanicum

    NASA Astrophysics Data System (ADS)

    Hartsock, J. A.; Vile, M. A.; Wieder, R.

    2011-12-01

    Boreal peatlands globally function as long-term sinks for atmosheric CO2. Mosses in the genus Sphagnum dominate the understory of boreal peatlands, especially in ombrotrophic bogs for which the sole sources of new nitrogen (N) is atmospheric deposition and biological N2-fixation. Sphagnum mosses in undisturbed regions generally are thought to be N-limited because of slow nutrient turnover and low rates of atmospheric N deposition. In Alberta, Canada, mean background N deposition rates are less than 1 kg N ha-1yr-1, but increasing atmospheric N deposition is occurring as a consequence of oil sands development in northern Alberta. In some European countries, anthropogenic practices have increased annual N deposition rates to levels in excess of 20 kg N ha-1yr-1. Increased rates of atmospheric N deposition have been shown to alter N cycling processes of Sphagnum mosses. Current hypotheses propose that Sphagnum mosses leach dissolved organic nitrogen (DON) from their tissues to mitigate N saturation stress in high N deposition areas. The goal of this study was to determine whether Sphagnum magellanicum leaches DON when exposed to elevated concentrations of NH4NO3 applied experimentally as synthetic rainfall. Sphagnum magellanicum was collected from a fen in Driftwood, Pennsylvania (41°13'58"N 78°11'44"W). Intact cores (10.5cm x 5.5cm) were grown in 500 mL culture flasks in a controlled environment chamber at Villanova University. Ammonium nitrate was applied to moss treatments eight times over 73 days at concentrations equivalent to 6 kg N ha-1yr-1, 12 kg N ha-1yr-1, and 18 kg N ha-1yr-1 (n=5 replicates per treatment, 400 mL H2O per N addition). Leachates (freely drained water samples) were analyzed for dissolved total nitrogen (TN), ammonium (NH4+-N), nitrate (NO3--N), and DON (TN-DIN) concentrations. Results show that after 73 days, increasing DIN resulted in: 1) a shift from net N mineralization to net NH4+ immobilization (Control: 376.3 ± 15.2 ug/g; High N: -377

  2. RX J0720.4-3125: Implications for neutron star cooling and the dense matter equation of state

    NASA Astrophysics Data System (ADS)

    Wang, John C. L.; Link, Bennett; van Riper, Kenneth; Arnaud, Keith A.; Miralles, Juan A.

    1999-05-01

    The soft X-ray source RX J0720.4-3125 appears to be a clean example of a cooling neutron star. Its X-ray emission is well-fit by a 79+/-4 eV blackbody and displays a periodic modulation with period P=8.391 sec and semi-amplitude ~ 10%. The observational upper limit to the period derivative implies a minimum spindown age of t0=1.7x 10(5) yr if the star was born rapidly rotating. The absence of a visible supernova remnant independently suggests an age for this source of gtrsim 10(5) yr. With the interpretation of this source as a cooling-driven, magnetized, rotating neutron star, we explore the implications for the dense matter equation of state (EOS), the mode of energy loss (modified URCA vs. direct URCA), and the rate of internal heating due to superfluid friction. For the standard (modified URCA) cooling models, we study two types of stars: those born slowly rotating, with relatively small spin-down rates and conventional dipole magnetic fields ( ~ 10(12) G), and those born rapidly rotating with large spin-down rates and magnetar-scale dipole fields ( ~ 10(14) G). We find that standard cooling with a stiff or moderately stiff EOS is consistent with the observations of RX J0720.4-3125 provided the star's age is ≲ 3 t_0=5*E(5) yr. If the EOS is very stiff, the star must be born with a short rotation period and significant internal heating by superfluid friction is required. More moderate heating suffices only if the star is very massive ( ~ 2 M_sun) and has an age ~ t_0. Stars with M ~ 1.4 M_sun and a moderately stiff EOS give modulations about a factor of five below that observed. However, the inclusion of atmospheric effects or more complex field geometries could increase the modulation to a level consistent with the observations. Stars with a stiff EOS give modulations close to that observed. As an illustration of the effects of accelerated cooling processes, we consider direct quark URCA cooling. We find that these models cool too fast and are cleanly ruled

  3. High-velocity extended molecular outflow in the star-formation dominated luminous infrared galaxy ESO 320-G030

    NASA Astrophysics Data System (ADS)

    Pereira-Santaella, M.; Colina, L.; García-Burillo, S.; Alonso-Herrero, A.; Arribas, S.; Cazzoli, S.; Emonts, B.; Piqueras López, J.; Planesas, P.; Storchi Bergmann, T.; Usero, A.; Villar-Martín, M.

    2016-10-01

    We analyze new high spatial resolution (~60 pc) ALMA CO(2-1) observations of the isolated luminous infrared galaxy ESO 320-G030 (d = 48 Mpc) in combination with ancillary Hubble Space Telescope optical and near infrared (IR) imaging, as well as VLT/SINFONI near-IR integral field spectroscopy. We detect a high-velocity (~450 km s-1) spatially resolved (size~2.5 kpc; dynamical time ~3 Myr) massive (~107 M⊙; Ṁ ~ 2-8 M⊙ yr-1) molecular outflow that has originated in the central ~250 pc. We observe a clumpy structure in the outflowing cold molecular gas with clump sizes between 60 and 150 pc and masses between 105.5 and 106.4 M⊙. The mass of the clumps decreases with increasing distance, while the velocity is approximately constant. Therefore, both the momentum and kinetic energy of the clumps decrease outwards. In the innermost (~100 pc) part of the outflow, we measure a hot-to-cold molecular gas ratio of 7 × 10-5, which is similar to that measured in other resolved molecular outflows. We do not find evidence of an ionized phase in this outflow. The nuclear IR and radio properties are compatible with strong and highly obscured star-formation (Ak ~ 4.6 mag; star formation rate ~ 15 M⊙ yr-1). We do not find any evidence for the presence of an active galactic nucleus. We estimate that supernova explosions in the nuclear starburst (νSN ~ 0.2 yr-1) can power the observed molecular outflow. The kinetic energy and radial momentum of the cold molecular phase of the outflow correspond to about 2% and 20%, respectively, of the supernovae output. The cold molecular outflow velocity is lower than the escape velocity, so the gas will likely return to the galaxy disk. The mass loading factor is ~0.1-0.5, so the negative feedback owing to this star-formation-powered molecular outflow is probably limited. The reduced images and datacubes (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc

  4. The price of snow: albedo valuation and a case study for forest management

    NASA Astrophysics Data System (ADS)

    Lutz, David A.; Howarth, Richard B.

    2015-06-01

    Several climate frameworks have included the role of carbon storage in natural landscapes as a potential mechanism for climate change mitigation. This has resulted in an incentive to grow and maintain intact long-lived forest ecosystems. However, recent research has suggested that the influence of albedo-related radiative forcing can impart equal and in some cases greater magnitudes of climate mitigation compared to carbon storage in forests where snowfall is common and biomass is slow-growing. While several methodologies exist for relating albedo-associated radiative forcing to carbon storage for the analysis of the tradeoffs of these ecosystem services, they are varied, and they have yet to be contrasted in a case study with implications for future forest management. Here we utilize four methodologies for calculating a shadow price for albedo radiative forcing and apply the resulting eight prices to an ecological and economic forest model to examine the effects on optimal rotation periods on two different forest stands in the White Mountain National Forest in New Hampshire, USA. These pricing methodologies produce distinctly different shadow prices of albedo, varying from a high of 9.36 × 10-4 and a low of 1.75 × 10-5 w-1yr-1 in the initial year, to a high of 0.019 and a low of 3.55 × 10-4 w-1yr-1 in year 200 of the simulation. When implemented in the forest model, optimal rotation periods also varied considerably, from a low of 2 to a high of 107 years for a spruce-fir stand and from 35 to 80 years for a maple-beech-birch stand. Our results suggest that the choice of climate metrics and pricing methodologies for use with forest albedo alter albedo prices considerably, may substantially adjust optimal rotation period length, and therefore may have consequences with respect to forest land cover change.

  5. Testing mechanisms of N-enrichment-induced species loss in a semiarid Inner Mongolia grassland: critical thresholds and implications for long-term ecosystem responses.

    PubMed

    Lan, Zhichun; Bai, Yongfei

    2012-11-19

    The increase in nutrient availability as a consequence of elevated nitrogen (N) deposition is an important component of global environmental change. This is likely to substantially affect the functioning and provisioning of ecosystem services by drylands, where water and N are often limited. We tested mechanisms of chronic N-enrichment-induced plant species loss in a 10-year field experiment with six levels of N addition rate. Our findings on a semi-arid grassland in Inner Mongolia demonstrated that: (i) species richness (SR) declined by 16 per cent even at low levels of additional N (1.75 g N m(-2) yr(-1)), and 50-70% species were excluded from plots which received high N input (10.5-28 g N m(-2) yr(-1)); (ii) the responses of SR and above-ground biomass (AGB) to N were greater in wet years than dry years; (iii) N addition increased the inter-annual variations in AGB, reduced the drought resistance of production and hence diminished ecosystem stability; (iv) the critical threshold for chronic N-enrichment-induced reduction in SR differed between common and rare species, and increased over the time of the experiment owing to the loss of the more sensitive species. These results clearly indicate that both abundance and functional trait-based mechanisms operate simultaneously on N-induced species loss. The low initial abundance and low above-ground competitive ability may be attributable to the loss of rare species. However, shift from below-ground competition to above-ground competition and recruitment limitation are likely to be the key mechanisms for the loss of abundant species, with soil acidification being less important. Our results have important implications for understanding the impacts of N deposition and global climatic change (e.g. change in precipitation regimes) on biodiversity and ecosystem services of the Inner Mongolian grassland and beyond. PMID:23045710

  6. Testing mechanisms of N-enrichment-induced species loss in a semiarid Inner Mongolia grassland: critical thresholds and implications for long-term ecosystem responses.

    PubMed

    Lan, Zhichun; Bai, Yongfei

    2012-11-19

    The increase in nutrient availability as a consequence of elevated nitrogen (N) deposition is an important component of global environmental change. This is likely to substantially affect the functioning and provisioning of ecosystem services by drylands, where water and N are often limited. We tested mechanisms of chronic N-enrichment-induced plant species loss in a 10-year field experiment with six levels of N addition rate. Our findings on a semi-arid grassland in Inner Mongolia demonstrated that: (i) species richness (SR) declined by 16 per cent even at low levels of additional N (1.75 g N m(-2) yr(-1)), and 50-70% species were excluded from plots which received high N input (10.5-28 g N m(-2) yr(-1)); (ii) the responses of SR and above-ground biomass (AGB) to N were greater in wet years than dry years; (iii) N addition increased the inter-annual variations in AGB, reduced the drought resistance of production and hence diminished ecosystem stability; (iv) the critical threshold for chronic N-enrichment-induced reduction in SR differed between common and rare species, and increased over the time of the experiment owing to the loss of the more sensitive species. These results clearly indicate that both abundance and functional trait-based mechanisms operate simultaneously on N-induced species loss. The low initial abundance and low above-ground competitive ability may be attributable to the loss of rare species. However, shift from below-ground competition to above-ground competition and recruitment limitation are likely to be the key mechanisms for the loss of abundant species, with soil acidification being less important. Our results have important implications for understanding the impacts of N deposition and global climatic change (e.g. change in precipitation regimes) on biodiversity and ecosystem services of the Inner Mongolian grassland and beyond.

  7. Does Newton’s gravitational constant vary sinusoidally with time? Orbital motions say no

    NASA Astrophysics Data System (ADS)

    Iorio, Lorenzo

    2016-02-01

    A sinusoidally time-varying pattern of the values of Newton’s constant of gravitation G measured in Earth-based laboratories over the last few decades has been recently reported in the literature. We put to the test the hypothesis that the aforementioned harmonic variation may pertain to G itself in a direct and independent way. We numerically integrated the ad hoc modified equations of motion of the major bodies of the Solar System, finding that the orbits of the planets would be altered by an unacceptably larger amount in view of the present-day high accuracy astrometric measurements. In the case of Saturn, its geocentric right ascension α, declination δ and range ρ would be affected by up to {10}4-{10}5 milliarcseconds and 105 km, respectively; the present-day residuals of such observables are as little as about 4 milliarcseconds and 10-1 km, respectively. We analytically calculated the long-term orbital effects induced by the putative harmonic variation of G at hand, finding non-zero rates of change for the semimajor axis a, the eccentricity e and the argument of pericenter ω of a test particle. For the LAGEOS satellite, an orbital increase as large as 3.9 m yr-1 is predicted, in contrast with the observed decay of -0.203 ± 0.035 m yr-1. An anomalous perihelion precession as large as 14 arcseconds per century is implied for Saturn, while latest observations constrain it to the 10-4 arcseconds per century level. The rejection level provided by the Mercury’s perihelion rate is of the same order of magnitude.

  8. Spatial and temporal effects of drought on soil CO2 efflux in a cacao agroforestry system in Sulawesi, Indonesia

    NASA Astrophysics Data System (ADS)

    van Straaten, O.; Veldkamp, E.; Köhler, M.; Anas, I.

    2010-04-01

    Climate change induced droughts pose a serious threat to ecosystems across the tropics and sub-tropics, particularly to those areas not adapted to natural dry periods. In order to study the vulnerability of cacao (Theobroma cacao) - Gliricidia sepium agroforestry plantations to droughts a large scale throughfall displacement roof was built in Central Sulawesi, Indonesia. In this 19-month experiment, we compared soil surface CO2 efflux (soil respiration) from three roof plots with three adjacent control plots. Soil respiration rates peaked at intermediate soil moisture conditions and decreased under increasingly dry conditions (drought induced), or increasingly wet conditions (as evidenced in control plots). The roof plots exhibited a slight decrease in soil respiration compared to the control plots (average 13% decrease). The strength of the drought effect was spatially variable - while some measurement chamber sites reacted strongly (responsive) to the decrease in soil water content (up to R2=0.70) (n=11), others did not react at all (non-responsive) (n=7). A significant correlation was measured between responsive soil respiration chamber sites and sap flux density ratios of cacao (R=0.61) and Gliricidia (R=0.65). Leaf litter CO2 respiration decreased as conditions became drier. The litter layer contributed approximately 3-4% of the total CO2 efflux during dry periods and up to 40% during wet periods. Within days of roof opening soil CO2 efflux rose to control plot levels. Thereafter, CO2 efflux remained comparable between roof and control plots. The cumulative effect on soil CO2 emissions over the duration of the experiment was not significantly different: the control plots respired 11.1±0.5 Mg C ha-1 yr-1, while roof plots respired 10.5±0.5 Mg C ha-1 yr-1. The relatively mild decrease measured in soil CO2 efflux indicates that this agroforestry ecosystem is capable of mitigating droughts with only minor stress symptoms.

  9. First Very Large Telescope/X-shooter spectroscopy of early-type stars outside the Local Group

    NASA Astrophysics Data System (ADS)

    Hartoog, O. E.; Sana, H.; de Koter, A.; Kaper, L.

    2012-05-01

    As part of the Very Large Telescope (VLT)/X-shooter science verification, we obtained the first optical medium-resolution spectrum of a previously identified bright O-type object in NGC 55, a Large Magellanic Cloud (LMC)-like galaxy at a distance of ˜2.0 Mpc. Based on the stellar and nebular spectra, we investigate the nature and evolutionary status of the central object(s) and its influence on the surrounding interstellar medium. We conclude that the source, NGC 55 C1_31, is a composite object, likely a stellar cluster, which contains one or several hot (Teff≃ 50 000 K) WN stars with a high mass-loss rate (˜3 × 10-5 M⊙ yr-1) and a helium-rich composition (NHe/NH= 0.8). The visual flux is dominated by OB-type (super)giant stars with Teff≲ 35 000 K, solar helium abundance (NHe/NH= 0.1) and mass-loss rate ˜2 × 10-6 M⊙ yr-1. The surrounding H II region has an electron density of ne≤ 102 cm-3 and an electron temperature of T(O III) ≃ 11 500 ± 600 K. The oxygen abundance of this region is [O/H] = 8.18 ± 0.03, which corresponds to Z= 0.31 ± 0.04 Z⊙. We observed no significant gradients in T(O III), ne or [O/H] on a scale of 73 pc extending in four directions from the ionizing source. The properties of the H II region can be reproduced by a CLOUDY model which uses the central cluster as ionizing source, thus providing a self-consistent interpretation of the data. We also report on the serendipitous discovery of He II nebular emission associated with the nearby source NGC 55 C2_35, a feature usually associated with strong X-ray sources.

  10. A search for ionized jets towards massive young stellar objects

    NASA Astrophysics Data System (ADS)

    Purser, S. J. D.; Lumsden, S. L.; Hoare, M. G.; Urquhart, J. S.; Cunningham, N.; Purcell, C. R.; Brooks, K. J.; Garay, G.; Gúzman, A. E.; Voronkov, M. A.

    2016-07-01

    Radio continuum observations using the Australia telescope compact array at 5.5, 9.0, 17.0 and 22.8 GHz have detected free-free emission associated with 45 of 49 massive young stellar objects and H II regions. Of these, 26 sources are classified as ionized jets (12 of which are candidates), 2 as ambiguous jets or disc winds, 1 as a disc-wind, 14 as H II regions and 2 were unable to be categorized. Classification as ionized jets is based upon morphology, radio flux and spectral index, in conjunction with previous observational results at other wavelengths. Radio luminosity and momentum are found to scale with bolometric luminosity in the same way as low-mass jets, indicating a common mechanism for jet production across all masses. In 13 of the jets, we see associated non-thermal/optically thin lobes resulting from shocks either internal to the jet and/or at working surfaces. 10 jets display non-thermal (synchrotron emission) spectra in their lobes, with an average spectral index of α = -0.55 consistent with Fermi acceleration in shocks. This shows that magnetic fields are present, in agreement with models of jet formation incorporating magnetic fields. Since the production of collimated radio jets is associated with accretion processes, the results presented in this paper support the picture of disc-mediated accretion for the formation of massive stars with an upper limit on the jet phase lasting approximately 6.5 × 104 yr. Typical mass-loss rates in the jet are found to be 1.4 × 10-5 M⊙ yr-1 with associated momentum rates of the order of (1-2) × 10-2 M⊙ km s-1 yr-1.

  11. The impact of mechanical AGN feedback on the formation of massive early-type galaxies

    NASA Astrophysics Data System (ADS)

    Choi, Ena; Ostriker, Jeremiah P.; Naab, Thorsten; Oser, Ludwig; Moster, Benjamin P.

    2015-06-01

    We employ cosmological hydrodynamical simulations to investigate the effects of AGN feedback on the formation of massive galaxies with present-day stellar masses of M_stel= 8.8 × 10^{10}-6.0 × 10^{11} M_{⊙}. Using smoothed particle hydrodynamics simulations with a pressure-entropy formulation that allows an improved treatment of contact discontinuities and fluid mixing, we run three sets of simulations of 20 haloes with different AGN feedback models: (1) no feedback, (2) thermal feedback, and (3) mechanical and radiation feedback. We assume that seed black holes are present at early cosmic epochs at the centre of emerging dark matter haloes and trace their mass growth via gas accretion and mergers with other black holes. Both feedback models successfully recover the observed MBH-σ relation and black hole-to-stellar mass ratio for simulated central early-type galaxies. The baryonic conversion efficiencies are reduced by a factor of 2 compared to models without any AGN feedback at all halo masses. However, massive galaxies simulated with thermal AGN feedback show a factor of ˜10-100 higher X-ray luminosities than observed. The mechanical/radiation feedback model reproduces the observed correlation between X-ray luminosities and velocity dispersion, e.g. for galaxies with σ = 200 km s- 1, the X-ray luminosity is reduced from 1042 erg s- 1 to 1040 erg s- 1. It also efficiently suppresses late-time star formation, reducing the specific star formation rate from 10-10.5 yr- 1 to 10-14 yr- 1 on average and resulting in quiescent galaxies since z = 2, whereas the thermal feedback model shows higher late-time in situ star formation rates than observed.

  12. A 3D numerical model for Kepler's supernova remnant

    NASA Astrophysics Data System (ADS)

    Toledo-Roy, J. C.; Esquivel, A.; Velázquez, P. F.; Reynoso, E. M.

    2014-07-01

    We present new 3D numerical simulations for Kepler's supernova remnant. In this work we revisit the possibility that the asymmetric shape of the remnant in X-rays is the product of a Type Ia supernova explosion which occurs inside the wind bubble previously created by an AGB companion star. Due to the large peculiar velocity of the system, the interaction of the strong AGB wind with the interstellar medium results in a bow shock structure. In this new model we propose that the AGB wind is anisotropic, with properties such as mass-loss rate and density having a latitude dependence, and that the orientation of the polar axis of the AGB star is not aligned with the direction of motion. The ejecta from the Type Ia supernova explosion is modelled using a power-law density profile, and we let the remnant evolve for 400 yr. We computed synthetic X-ray maps from the numerical results. We find that the estimated size and peculiar X-ray morphology of Kepler's supernova remnant are well reproduced by considering an AGB mass-loss rate of 10-5 M⊙ yr-1, a wind terminal velocity of 10 km s-1, an ambient medium density of 10-3 cm-3 and an explosion energy of 7 × 1050 erg. The obtained total X-ray luminosity of the remnant in this model reaches 6 × 1050 erg, which is within a factor of 2 of the observed value, and the time evolution of the luminosity shows a rate of decrease in recent decades of ˜2.4 per cent yr-1 that is consistent with the observations.

  13. The Sub 0.1 fm Experimental Value of the Electron Radius, the Inability to Create or Annihilate an Electron even by TeV Energies, the Impossibility of Kinetic Energy Transfer to an Electron from a Particle of a 10^5 Times Smaller Mass, the Belief in Mass-Energy Equivalence (MEE) and the Electron Positron Lattice (EPOLA) Model of Space

    NASA Astrophysics Data System (ADS)

    Simhony, Menahem

    2003-04-01

    Scientists would not believe that the appearance and disappearance of rabbits in a magic box means their creation and annihilation by energy signals. However the belief in MEE made the results of the Anderson Experiment (1932) be accepted as creation and annihilation of particles out of and into energy, though never since was there a single electron created or annihilated in empy space, even now with muli TeV energies, and though phenomena obtain simple physical explanations as due to the epola structure of space,1, while the MEE fails. E.g., MEE yields the 2.82 fm value for the "classical electron radius" while scattering of fast electron beams proves (since the 1980's) that the electron radius must be below 0.1fm, and the value obtained then in the epola model is 0.094fm. Thus the density of matter in the electron is 3 10^17 kg/m^3, as in all stable nuclear particles known on earth. Another crush of MEE is the physically impossible direct transfer of kinetic energy from a several eV photon to a free electron of 511,000 eV MEE, as in Einstein's 1905 interpretation of the photo-electric effect. The solution is that the acting particle is an epola electron or positron that momentarily carries the photon energy and is thus able to transfer it to a nuclear particle of comparable mass. See:1.M.Simhony, Invitation to the Natural Physics of Matter, Space, and Radiation, World Scientific, 1994, ISBN 981-02-1649-1. Website: www.word1.co.il/physics

  14. Global simulation of tropospheric O3-NO x -hydrocarbon chemistry: 1. Model formulation

    NASA Astrophysics Data System (ADS)

    Wang, Yuhang; Jacob, Daniel J.; Logan, Jennifer A.

    1998-05-01

    We describe a global three-dimensional model for tropospheric O3-NOx-hydrocarbon chemistry with synoptic-scale resolution. A suite of 15 chemical tracers, including O3, NOx, PAN, HNO3, CO, H2O2, and various hydrocarbons, is simulated in the model. For computational expediency, chemical production and loss of tracers are parameterized as polynomial functions to fit the results of a detailed O3-NOx-hydrocarbon mechanism. The model includes state-of-the-art inventories of anthropogenic emissions and process-based formulations of natural emissions and deposition that are tied to the model meteorology. Improvements are made to existing schemes for computing biogenic emissions of isoprene and NO. Our best estimates of global emissions include among others 42 Tg N yr-1 for NOx (21 Tg N yr-1 from fossil fuel combustion, 12 Tg N yr-1 from biomass burning, 6 Tg N yr-1 from soils, and 3 Tg N yr-1 from lightning), and 37 Tg C yr-1 for acetone (1 Tg C yr-1 from industry, 9 Tg C yr-1 from biomass burning, 15 Tg C yr-1 from vegetation, and 12 Tg C yr-1 from oxidation of propane and higher alkanes).

  15. HST/WFC3 Near-Infrared Spectroscopy of Quenched and Mildly Star Forming Galaxies at 1.4 from WISPs: Stellar Population Properties

    NASA Astrophysics Data System (ADS)

    Bedregal, Alejandro; Scarlata, C.; WISP Survey Team

    2013-01-01

    We combine HST G102 and G141 near-IR grism spectroscopy with HST/UVIS, HST/WFC3 and Spitzer/IRAC[3.6 micron] photometry to assemble a sample of massive (M_star/M_sun = 11.0 dex) and rather passive galaxies at 1.4. After restricting to masses above 10.65 dex, this sample of 80 sources is the largest with homogeneous near-IR spectroscopy for this kind of galaxies at these redshifts. In contrast to the local Universe, we find the mass range above 10.65 dex is populated by galaxies with a wide range of properties. Although our color selection excludes from the sample typical SF massive galaxies, we still find two populations characterized by distinctive average luminosity-weighted ages and star-formation time-scales, but having similar mass and redshift distributions. The spectral energy distributions of Quenched galaxies (SSFR=<10^-2Gyr^-1) are well fitted with exponentially decreasing SFHs, and short star-formation timescales (tau=10-100Myr). They also show a wide distribution in ages, between 1 and 3 Gyrs. On the other hand, we also find a population of low SSFR galaxies (SSFR >10^-2Gyr.^-1) which show more extended SFHs (tau=0.1-1Gyr), being mostly old 3Gyr), and with higher A_V extinctions than the quenched galaxies. Given the stellar mass range covered by our SF galaxies, we find that their SFRs are low compared to normal SF galaxies at these redshifts (median SF 7M_sun yr^-1). We find that the old and massive population of mild-SF galaxies has properties inconsistent with them being a rejuvenated version of the quenched population at the same redshift. This possibly implies that the two samples originate from different mechanisms. In particular, the stellar-population properties of the quenched galaxies are consistent with being the result of gas-rich major mergers, well before the epoch of observation, and with a quick truncation of the SF after the merger. Instead, the properties of the old and mild-SF galaxies are in better agreement with a more extended

  16. Star formation rate in galaxies from UV, IR, and Hα estimators

    NASA Astrophysics Data System (ADS)

    Hirashita, H.; Buat, V.; Inoue, A. K.

    2003-10-01

    Infrared (IR) luminosity of galaxies originating from dust thermal emission can be used as an indicator of the star formation rate (SFR). Inoue et al. (\\cite{inoue00}, IHK) have derived a formula for the conversion from dust IR luminosity to SFR by using the following three quantities: the fraction of Lyman continuum luminosity absorbed by gas (f), the fraction of UV luminosity absorbed by dust (epsilon ), and the fraction of dust heating from old (ga 108 yr) stellar populations (eta ). We develop a method to estimate those three quantities based on the idea that the various way of SFR estimates from ultraviolet (UV) luminosity (2000 Å luminosity), Hα luminosity, and dust IR luminosity should return the same SFR. After applying our method to samples of galaxies, the following results are obtained in our framework. First, our method is applied to a sample of star-forming galaxies, finding that f ~ 0.6, epsilon ~ 0.5, and eta ~ 0.4 as representative values. Next, we apply the method to a starburst sample, which shows larger extinction than the star-forming galaxy sample. With the aid of f, epsilon , and eta , we are able to estimate reliable SFRs from UV and/or IR luminosities. Moreover, the Hα luminosity, if the Hα extinction is corrected by using the Balmer decrement, is suitable for a statistical analysis of SFR, because the same {correction factor for the Lyman continuum extinction (i.e. 1/f)} is applicable to both normal and starburst galaxies over all the range of SFR. The metallicity dependence of f and epsilon is also tested: Only the latter proves to have a correlation with metallicity. As an extension of our result, the local (z=0) comoving density of SFR can be estimated with our dust extinction corrections. We show that all UV, Hα , and IR comoving luminosity densities at z=0 give a consistent SFR per comoving volume ( ~ 3x 10-2h M_sun yr-1 Mpc-3). Useful formulae for SFR estimate are listed. Tables 1 and 2, and Appendix A are only available in

  17. The Spitzer c2d Survey of Nearby Dense Cores. IX. Discovery of a Very Low Luminosity Object Driving a Molecular Outflow in the Dense Core L673-7

    NASA Astrophysics Data System (ADS)

    Dunham, Michael M.; Evans, Neal J.; Bourke, Tyler L.; Myers, Philip C.; Huard, Tracy L.; Stutz, Amelia M.

    2010-10-01

    We present new infrared, submillimeter, and millimeter observations of the dense core L673-7 and report the discovery of a low-luminosity, embedded Class 0 protostar driving a molecular outflow. L673-7 is seen in absorption against the mid-infrared background in 5.8, 8, and 24 μm Spitzer images, allowing for a derivation of the column density profile and total enclosed mass of L673-7, independent of dust temperature assumptions. Estimates of the core mass from these absorption profiles range from 0.2to4.5 M sun. Millimeter continuum emission indicates a mass of ~2 M sun, both from a direct calculation assuming isothermal dust and from dust radiative transfer models constrained by the millimeter observations. We use dust radiative transfer models to constrain the internal luminosity of L673-7, defined to be the luminosity of the central source and excluding the luminosity from external heating, to be L int = 0.01-0.045 L sun, with L int ~ 0.04 L sun the most likely value. L673-7 is thus classified as a very low luminosity object (VeLLO), and is among the lowest luminosity VeLLOs yet studied. We calculate the kinematic and dynamic properties of the molecular outflow in the standard manner. From the outflow properties and standard assumptions regarding the driving of outflows, we calculate the time-averaged protostellar mass accretion rate, total protostellar mass accreted, and expected accretion luminosity to be < \\dot{M}_acc > ≥ 1.2 × 10^{-6} sin i {cos}^2 i Msun yr-1, M_acc ≥ 0.07 {1}/{cos } M sun, and Lacc >= 0.36 L sun, respectively. The discrepancy between this calculated L acc and the L int derived from dust radiative transfer models indicates that the current accretion rate is much lower than the average rate over the lifetime of the outflow. Although the protostar embedded within L673-7 is consistent with currently being substellar, it is unlikely to remain as such given the substantial mass reservoir remaining in the core.

  18. Does the Galactic centre cloud G0.253+0.016 violate star formation relations?

    NASA Astrophysics Data System (ADS)

    Johnston, Katharine; Beuther, Henrik; Longmore, Steven; Rathborne, Jill; Ragan, Sarah

    2013-07-01

    The massive infrared dark cloud G0.253+0.016 near the Galactic centre contains 10^5 Msun of dense gas whilst being mostly devoid of observed star formation tracers. Thus G0.253+0.016 violates the recently proposed "star formation law" of Lada et al. (2010), which suggests a relation between the mass above a column density threshold of 0.024 gcm^-2 and the observed star formation rate. In fact, a recent study by Longmore et al. (2013) has shown that the SFR over the Galactic centre region appears to be an order of magnitude lower than predicted by the mass of dense gas. To scrutinize the gas properties of G0.253+0.016, we have carried out a concerted SMA and IRAM 30m study of this enigmatic cloud in dust continuum, CO isotopologues as low-density tracers, and CH3OH, SO, SiO and HNCO as shock tracers. In this poster, we discuss 1) how our results suggest that G0.253+0.016 is colliding with another cloud, which could affect its final star-forming fate, 2) the density structure of the cloud with relation to whether star formation is currently ongoing, and 3) whether it is possible to reconcile the lack of star formation in G0.253+0.016 and the Galactic centre with the density threshold for star formation, found for the Milky Way disk and external galaxies, by considering the effects of turbulent support.

  19. The PdBI Arcsecond Whirlpool Survey (PAWS) III. How Dynamical Environments Regulate the Structure of the Molecular Gas and Star Formation in M51

    NASA Astrophysics Data System (ADS)

    Meidt, Sharon; Schinnerer, E.; Hughes, A.; Garcia Burillo, S.; Colombo, D.; Pety, J.; Leroy, A. K.; Dobbs, C.; Dumas, G.; Schuster, K. F.; Thompson, T. A.; Kramer, C.

    2013-01-01

    Gas kinematics on the scales of Giant Molecular Clouds (GMCs) are essential for probing the framework that links the large-scale organization of interstellar gas to cloud formation and subsequent star formation. We will present an overview of our results on the importance of dynamical environment for molecular gas and star formation from the PdBI Arcsecond Whirlpool Survey (PAWS, PI: E. Schinnerer), which has mapped CO(1-0) emission in the nearby grand-design spiral galaxy M51 at 40pc resolution and is sensitive to giant molecular clouds (GMCs) with masses above 10^5 Msun. The observed gas motions suggest a strong response to the gravitational forces exerted by the stellar spiral arms, and we find that the properties of the CO emission in M51 show significant variation that can be linked to the (galactic) dynamical environment in which the molecular gas is located. Dynamically distinct regions exhibit different GMC properties and mass spectra, as well as distinct patterns of star formation. We have analyzed how the stability of GMCs depends on dynamical environment (including the effects of pressure, shear, turbulence). We will discuss the impact of our results on the interpretation of standard GMC scaling relations and as a potential source of the observed scatter in extragalactic star formation laws.

  20. Constraints on single-degenerate Chandrasekhar mass progenitors of Type Iax supernovae

    NASA Astrophysics Data System (ADS)

    Liu, Zheng-Wei; Moriya, Takashi J.; Stancliffe, Richard J.; Wang, Bo

    2015-02-01

    Context. Type Iax supernovae (SNe Iax) are proposed as one new sub-class of SNe Ia since they present sufficiently distinct observational properties from the bulk of SNe Ia. Observationally, SNe Iax have been estimated to account for ~5%-30% of the total SN Ia rate, and most SNe Iax have been discovered in late-type galaxies. In addition, observations constrain the progenitor systems of some SN Iax progenitors that have ages of <80 Myr. Although the identity of the progenitors of SNe Iax is unclear, the weak deflagration explosions of Chandrasekhar-mass (Ch-mass) carbon/oxygen white dwarfs (C/O WDs) seem to provide a viable physical scenario. Aims: Comparing theoretical predictions from binary population synthesis (BPS) calculations with observations of SNe Iax, we put constraints on the single-degenerate (SD) Ch-mass model as a possible SN Iax progenitor. Methods: Based on the SD Ch-mass model, the SN rates and delay times are predicted by combining binary evolution calculations for the progenitor systems into a BPS model. Moreover, with current X-ray observations of SNe Iax, we constrain the pre-explosion mass-loss rates of stellar progenitor systems by using two analytic models. Results: From our calculations, the long delay times of ≳3 Gyr and low SN rates of ~3 × 10-5 yr-1 are found in the red-gaint donor channel, indicating that this channel is unlikely to produce SNe Iax. With our standard models, we predict that the Galactic SN Iax rate from the main-sequence (helium-star) donor scenario is ~1.5 × 10-3 yr-1 (~3 × 10-4 yr-1). The total rate of these two models is consistent with the observed SN Iax rate. The short delay times in the helium-star donor channel (<100 Myr) support the young host environments of SNe Iax. However, the relatively long delay times in the main-sequence donor channel (~250 Myr-1 Gyr) are less favourable for the observational constraints on the ages of SN Iax progenitors. Finally, with current X-ray observations for SNe Iax, we

  1. Wet and dry deposition of mineral dust particles in Japan: factors related to temporal variation and spatial distribution

    NASA Astrophysics Data System (ADS)

    Osada, K.; Ura, S.; Kagawa, M.; Mikami, M.; Tanaka, T. Y.; Matoba, S.; Aoki, K.; Shinoda, M.; Kurosaki, Y.; Hayashi, M.; Shimizu, A.; Uematsu, M.

    2014-01-01

    Recent ground networks and satellite remote-sensing observations have provided useful data related to spatial and vertical distributions of mineral dust particles in the atmosphere. However, measurements of temporal variations and spatial distributions of mineral dust deposition fluxes are limited in terms of their duration, location, and processes of deposition. To ascertain temporal variations and spatial distributions of mineral dust deposition using wet and dry processes, weekly deposition samples were obtained at Sapporo, Toyama, Nagoya, Tottori, Fukuoka, and Cape Hedo (Okinawa) in Japan during October 2008-December 2010 using automatic wet and dry separating samplers. Mineral dust weights in water-insoluble residue were estimated from Fe contents measured using an X-ray fluorescence analyser. Wet and dry deposition fluxes of mineral dusts were both high in spring and low in summer, showing similar seasonal variations to frequency of aeolian dust events (Kosa) in Japan. For wet deposition, highest and lowest annual dust fluxes were found at Toyama (9.6 g m-2 yr-1) and at Cape Hedo (1.7 g m-2 yr-1) as average values in 2009 and 2010. Higher wet deposition fluxes were observed at Toyama and Tottori, where frequent precipitation (> 60% days per month) was observed during dusty seasons. For dry deposition among Toyama, Tottori, Fukuoka, and Cape Hedo, the highest and lowest annual dust fluxes were found respectively at Fukuoka (5.2 g m-2 yr-1) and at Cape Hedo (2.0 g m-2 yr-1) as average values in 2009 and 2010. The average ratio of wet and dry deposition fluxes was the highest at Toyama (3.3) and the lowest at Hedo (0.82), showing a larger contribution of the dry process at western sites, probably because of the distance from desert source regions and because of the effectiveness of the wet process in the dusty season. Size distributions of refractory dust particles were obtained using four-stage filtration: > 20, > 10, > 5, and > 1 μm diameter. Weight fractions

  2. WSRT HI imaging of candidate gas-bearing dark matter halos in the Local Group

    NASA Astrophysics Data System (ADS)

    Adams, Elizabeth A.; Oosterloo, Tom; Cannon, John M.; Giovanelli, Riccardo; Haynes, Martha P.

    2016-01-01

    A long standing problem in cosmology is the mismatch between the number of low mass dark matter halos predicted by simulations and the number of low mass galaxies observed in the Local Group. We recently presented a set of isolated ultra-compact high velocity clouds (UCHVCs) identified within the dataset of the Arecibo Legacy Fast ALFA (ALFALFA) HI line survey that are consistent with representing low mass gas-bearing dark matter halos within the Local Group (Adams+ 2013). At distances of ~1 Mpc, the UCHVCs have HI masses of ~10^5 Msun and indicative dynamical masses of ~10^7 Msun. The HI diameters of the UCHVCs range from 4' to 20', or 1 to 6 kpc at a distance of 1 Mpc. We have selected the most compact and isolated UCHVCs with the highest average column densities as representing the best galaxy candidates. These systems have been observed with the Westerbork Synthesis Radio Telescope (WSRT) to enable higher spatial resolution studies of the HI distribution. From these data, the sources break into two clear categories. Two of the sources maintain a smooth HI morphology at higher resolution, show a velocity gradient and have the highest peak column densities of the sample, indicating they are good candidates to represent gas in dark matter halos. In fact, one of these sources, AGC 198606, has a tentative stellar counterpart detection (Janesh+ 2015). Nine of the sources break into clumps at higher angular resolution, show no ordered velocity motion, and have significantly lower peak column densities, indicating they are likely Galactic halo HI clouds. One source straddles the two categories with a relatively smooth HI morphology and some evidence for ordered velocity motion while having a lower peak column density. These observations show that higher resolution HI data is a good way to address the galaxy hypothesis for isolated HI clouds, and future HI surveys with phased-array feeds on interferometers, such as Apertif, will be able to directly detect and

  3. Critical tests of stellar evolution in open clusters. II. Membership, duplicity, and stellar and dynamical evolution in NGC 3680.

    NASA Astrophysics Data System (ADS)

    Nordstroem, B.; Andersen, J.; Andersen, M. I.

    1997-06-01

    Based on new, accurate photometry, radial velocities, and proper motions for the intermediate-age open cluster NGC 3680, we identify individual single and binary cluster members and field stars in the colour-magnitude diagram (CMD). This basic step turns out to be crucial for a proper understanding of the cluster CMD: ~60% of the stars are found to be field stars, and over 50% of the cluster stars are binaries. No bona fide cluster star is found more than 1.5mag below the turnoff, and cluster stars below 1.4Msun_ are only found in binary systems. The total present mass of NGC 3680 is ~100Msun_, excluding any as yet unseen stellar remnants, and its half-mass radius is 3.3' (1.2pc). Comparison with plausible IMFs indicates that only ~3% of the original stars and <~10% of the mass now survive, ~30% of the initial mass being in the form of massive stars that have now completed their evolution, and ~60% in low-mass stars which may now be located in a distant cluster halo or perhaps have been lost entirely. The single main-sequence cluster members form an extremely tight sequence in the CMD, with E_(b-y)_=0.034 and [Fe/H]=+0.11. A direct fit to the Hyades main sequence yields (m-M)_0_=10.5+/-0.2 for NGC 3680. Isochrones from several stellar models have been fit to the cluster sequence. When based on consistent uvby colour transformations and the above cluster parameters, these fits are very stable and show that standard models are not acceptable for stars with the turnoff mass of NGC 3680. Overshooting models perform much better, but further refinement of the overshooting formalism seems to be needed. The age derived for NGC 3680 is 1.45+/-0.3Gyr. The limiting factor in a precise comparison of theory and observations is now the transformation from theoretical to observed parameters, particularly (broad-band) colours.

  4. Quantification of Carbon Fluxes in Tropical Deciduous Forests Using Satellite Data

    NASA Astrophysics Data System (ADS)

    Prasad, V. Krishna; Rajagopal, T.; Kant, Yogesh; Badarinath, K. V. S.

    Biomass burning in tropics is causing drastic changes in physical, chemical and biological properties of earth's atmosphere. Biomass burning associated with slash and burn agriculture is one of the major cause of Green House Gas emissions. In the present study, study area covering tropical deciduous forests having slash and burn agriculture practice, has been considered for studying carbon dynamics. Satellite data pertaining to IRS-1C LISS III satellite data has been used for stratification of vegetation into different communities. Second order texture measures Semivariograms, Angular Second Moment (ASM) and Inverse Difference Moment (IDM) and NDVI textural algorithm have been used to capture spatial information from forest stands. Biomass estimations have been done through regression equations by using girth measurements obtained through field studies. Satellite data has been used to quantify the amount of biomass burnt in respective vegetation types. Results of the study through textural measures suggest high heterogeneity in canopy diversity for mixed dry deciduous forests. ASM and IDM are found to be high for pure stands of dry deciduous forests. NDVI textural algorithm detected a low spatial variability with respect to mixed dry deciduous forests suggesting homogeneity in plant biomass spatial variability. The average mean carbon storage has been found to be 64.34 t ha-1 C for dry deciduous forests, 129.0 t ha-1 C for mixed dry deciduous forests and 0.02 t ha-1 C for mixed scrub forests. Potential Net primary productivity for the forests ranged from 26.07 to 11.73 t ha-1 yr-1, when compared to actual productivity of 0.1 t ha-1 yr-1 to 4.6 t ha-1 yr-1. Mean carbon storage for plantations, above ground, below ground and total carbon has been found to be 16.84, 3.36 and 20.2 t ha-1 C respectively. Dry matter burnt in gms (M) obtained from satellite derived areal estimates has been found to be 1.344 × 1012 gms. Area weighted carbon release for the total study

  5. Clump formation through colliding stellar winds in the Galactic Center

    NASA Astrophysics Data System (ADS)

    Calderón, Diego

    2016-07-01

    The gas cloud G2 is currently being tidally disrupted by the Galactic Center super-massive black hole, Sgr A*. The region around the black hole is populated by ˜30 Wolf-Rayet stars, which produce strong outflows. Following an analytical approach, we explore the possibility that gas clumps, such as G2, originate from the collision of identical stellar winds via the Non-Linear Thin Shell Instability. We have found that the collision of relatively slow (<750 km s^{-1}) and strong (˜10^{-5} M_{⊙} yr^{-1}) stellar winds from stars at short separations (<2000 AU) is a process that indeed could produce clumps of G2's mass and above. Such short separation encounters of single stars along their orbits are not common in the Galactic Centre, however close binaries, such as IRS 16SW, are promising clump sources (see Calderón et al. 2016). We also present the first results of 2D models of colliding wind systems using the hydrodynamics adaptive mesh refinement code RAMSES, aiming to obtain a clump mass function, and the rate of clump formation and ejection to the ISM. We study the effect of parameters such as wind properties, stellar separation and orbital motion, in order to understand how likely the formation of G2 is in this context.

  6. Nutrient and population dynamics in a subglacial reservoir: a simulation case study of the Blood Falls ecosystem with implications for astrobiology

    NASA Astrophysics Data System (ADS)

    Fisher, Thomson Mason; Schulze-Makuch, Dirk

    2013-10-01

    Subglacial ecosystems have recently become of interest within the astrobiological community, as they represent a potentially habitable location in otherwise uninhabitable environments. We used data from Blood Falls, particularly the periodic discharge from the subglacial reservoir beneath Taylor Glacier, Antarctica, to construct an ecosystem model of the putative subglacial microbial community residing there using system dynamics modelling. The model results were, for the most part, within an order of magnitude of the geochemical field data. Productivity was quite low, at 6.4×10-5 g carbon l-1 yr-1. Based on the results, we draw the following conjectures for the search for life on Mars: A similar ecosystem would require a continual supply of oxidized iron for energy and generate significant amounts of reduced iron as a waste product, be relatively resilient to temporary disturbances, and, thermodynamically, would require at least 0.003 kJ mol l-1 of energy to survive at that level of productivity. These results may help to better identify the constraints and boundaries of ecosystems in extreme environments, on Earth and other planetary bodies.

  7. He-accreting white dwarfs: accretion regimes and final outcomes

    NASA Astrophysics Data System (ADS)

    Piersanti, L.; Tornambé, A.; Yungelson, L. R.

    2014-12-01

    The behaviour of carbon-oxygen (CO) white dwarfs (WDs) subject to direct helium accretion is extensively studied. We aim to analyse the thermal response of an accreting WD to mass deposition at different timescales. The analysis has been performed for initial WD masses and accretion rates in the range 0.60-1.02 M⊙ and 10-9-10-5 M⊙ yr-1, respectively. Thermal regimes in the parameter space MWD-dot{M}_He leading to formation of red-giant-like structures, steady burning of He, and mild, strong and dynamical flashes have been identified and the transition between these regimes has been studied in detail. In particular, the physical properties of WDs experiencing the He-flash accretion regime have been investigated to determine the mass retention efficiency as a function of the accretor total mass and accretion rate. We also discuss to what extent the building up of a He-rich layer via H burning could be described according to the behaviour of models accreting He-rich matter directly. Polynomial fits to the obtained results are provided for use in binary population synthesis computations. Several applications for close binary systems with He-rich donors and CO WD accretors are considered and the relevance of the results for interpreting He novae is discussed.

  8. Experimental burial inhibits methanogenesis and anaerobic decomposition in water-saturated peats.

    PubMed

    Blodau, Christian; Siems, Melanie; Beer, Julia

    2011-12-01

    A mechanistic understanding of carbon (C) sequestration and methane (CH(4)) production is of great interest due to the importance of these processes for the global C budget. Here we demonstrate experimentally, by means of column experiments, that burial of water saturated, anoxic bog peat leads to inactivation of anaerobic respiration and methanogenesis. This effect can be related to the slowness of diffusive transport of solutes and evolving energetic constraints on anaerobic respiration. Burial lowered decomposition constants in homogenized peat sand mixtures from about 10(-5) to 10(-7) yr(-1), which is considerably slower than previously assumed, and methanogenesis slowed down in a similar manner. The latter effect could be related to acetoclastic methanogenesis approaching a minimum energy quantum of -25 kJ mol(-1) (CH(4)). Given the robustness of hydraulic properties that locate the oxic-anoxic boundary near the peatland surface and constrain solute transport deeper into the peat, this effect has likely been critical for building the peatland C store and will continue supporting long-term C sequestration in northern peatlands even under moderately changing climatic conditions. PMID:21958021

  9. Lead (Pb) fluxes and Pb isotopic compositions from Masaya Volcano, Nicaragua

    NASA Astrophysics Data System (ADS)

    Vallelonga, P.; Mather, T. A.

    We report Pb concentrations and isotopic compositions measured in plume aerosol and Pele's hair (lava) samples collected from Masaya volcano, Nicaragua, to provide the first data pertaining to Pb emissions from the Central American volcanic arc. Lead isotopic compositions, determined by Thermal Ionisation Mass Spectrometry, in the Pele's hair samples were found to be 206Pb/ 207Pb˜1.196, 208Pb/ 207Pb˜2.46 and 206Pb/ 204Pb˜18.6. Mean Pb fluxes from Masaya were calculated to be 1.0 ton Pb yr -1 with a mean plume Pb/S (gas) ratio of 1.3×10 -5. Also, it was found that the majority of Pb emitted was present in the fine aerosol (<2.5 μm diameter) fraction but that the percentage of Pb in the fine aerosol fraction decreased from 96% in the dry daytime plume to 61% in the condensed night-time plume. The contribution from the filter blank was usually a substantial fraction of the total amount of Pb measured, requiring the data to be corrected for blank contributions using Pb isotopic systematics.

  10. Detecting leaks in gas-filled pressure vessels using acoustic resonances.

    PubMed

    Gillis, K A; Moldover, M R; Mehl, J B

    2016-05-01

    We demonstrate that a leak from a large, unthermostatted pressure vessel into ambient air can be detected an order of magnitude more effectively by measuring the time dependence of the ratio p/f(2) than by measuring the ratio p/T. Here f is the resonance frequency of an acoustic mode of the gas inside the pressure vessel, p is the pressure of the gas, and T is the kelvin temperature measured at one point in the gas. In general, the resonance frequencies are determined by a mode-dependent, weighted average of the square of the speed-of-sound throughout the volume of the gas. However, the weighting usually has a weak dependence on likely temperature gradients in the gas inside a large pressure vessel. Using the ratio p/f(2), we measured a gas leak (dM/dt)/M ≈ - 1.3 × 10(-5) h(-1) = - 0.11 yr(-1) from a 300-liter pressure vessel filled with argon at 450 kPa that was exposed to sunshine-driven temperature and pressure fluctuations as large as (dT/dt)/T ≈ (dp/dt)/p ≈ 5 × 10(-2) h(-1) using a 24-hour data record. This leak could not be detected in a 72-hour record of p/T. (Here M is the mass of the gas in the vessel and t is the time.).

  11. Bacteria in deep coastal plain sediments of Maryland: A possible source of CO2 to groundwater

    NASA Astrophysics Data System (ADS)

    Chapelle, Francis H.; Zelibor, Joseph L., Jr.; Grimes, D. Jay; Knobel, Leroy L.

    1987-08-01

    Nineteen cores of unconsolidated Coastal Plain sediments obtained from depths of 14 to 182 m below land surface near Waldorf, Maryland, were collected and examined for metabolically active bacteria. The age of the sediments cored range from Miocene to Early Cretaceous. Acridine orange direct counts of total (viable and nonviable) bacteria in core subsamples ranged from 108 to 104 bacteria/g of dry sediment. Direct counts of viable bacteria ranged from 106 to 103 bacteria/g of dry sediment. Three cores contained viable methanogenic bacteria, and seven cores contained viable sulfate-reducing bacteria. The observed presence of bacteria in these sediments suggest that heterotrophic bacterial metabolism, with lignitic organic material as the primary substrate, is a plausible source of CO2 to groundwater. However, the possibility that abiotic processes also produce CO2 cannot be ruled out. Estimated rates of CO2 production in the noncalcareous Magothy/Upper Patapsco and Lower Patapsco aquifers based on mass balance of dissolved inorganic carbon, groundwater flow rates, and flow path segment lengths are in the range 10-3 to 10-5 mmol L-1 yr-1. Isotope balance calculations suggest that aquifer-generated CO2 is much heavier isotopically (˜—10 to + 5 per mil) than lignite (˜-24 per mil) present in these sediments. This may reflect isotopic fractionation during methanogenesis and possibly other bacterially mediated processes.

  12. The nature of supernovae 2010O and 2010P in Arp 299 - II. Radio emission

    NASA Astrophysics Data System (ADS)

    Romero-Cañizales, C.; Herrero-Illana, R.; Pérez-Torres, M. A.; Alberdi, A.; Kankare, E.; Bauer, F. E.; Ryder, S. D.; Mattila, S.; Conway, J. E.; Beswick, R. J.; Muxlow, T. W. B.

    2014-05-01

    We report radio observations of two stripped-envelope supernovae (SNe), 2010O and 2010P, which exploded within a few days of each other in the luminous infrared galaxy Arp 299. Whilst SN 2010O remains undetected at radio frequencies, SN 2010P was detected (with an astrometric accuracy better than 1 milli arcsec in position) in its optically thin phase in epochs ranging from ˜1 to ˜3 yr after its explosion date, indicating a very slow radio evolution and a strong interaction of the SN ejecta with the circumstellar medium. Our late-time radio observations towards SN 2010P probe the dense circumstellar envelope of this SN, and imply dot{M} [ {M_{⊙} yr^{-1}}] / v_{wind} [10 km s^{-1}] =(3.0-5.1) × 10-5, with a 5 GHz peak luminosity of ˜1.2 × 1027 erg s- 1 Hz- 1 on day ˜464 after explosion. This is consistent with a Type IIb classification for SN 2010P, making it the most distant and most slowly evolving Type IIb radio SN detected to date.

  13. Detecting leaks in gas-filled pressure vessels using acoustic resonances

    NASA Astrophysics Data System (ADS)

    Gillis, K. A.; Moldover, M. R.; Mehl, J. B.

    2016-05-01

    We demonstrate that a leak from a large, unthermostatted pressure vessel into ambient air can be detected an order of magnitude more effectively by measuring the time dependence of the ratio p/f2 than by measuring the ratio p/T. Here f is the resonance frequency of an acoustic mode of the gas inside the pressure vessel, p is the pressure of the gas, and T is the kelvin temperature measured at one point in the gas. In general, the resonance frequencies are determined by a mode-dependent, weighted average of the square of the speed-of-sound throughout the volume of the gas. However, the weighting usually has a weak dependence on likely temperature gradients in the gas inside a large pressure vessel. Using the ratio p/f2, we measured a gas leak (dM/dt)/M ≈ - 1.3 × 10-5 h-1 = - 0.11 yr-1 from a 300-liter pressure vessel filled with argon at 450 kPa that was exposed to sunshine-driven temperature and pressure fluctuations as large as (dT/dt)/T ≈ (dp/dt)/p ≈ 5 × 10-2 h-1 using a 24-hour data record. This leak could not be detected in a 72-hour record of p/T. (Here M is the mass of the gas in the vessel and t is the time.)

  14. Hydrogen consumption by methanogens on the early Earth

    NASA Technical Reports Server (NTRS)

    Kral, T. A.; Brink, K. M.; Miller, S. L.; McKay, C. P.; Bada, J. L. (Principal Investigator)

    1998-01-01

    It is possible that the first autotroph used chemical energy rather than light. This could have been the main source of primary production after the initial inventory of abiotic organic material had been depleted. The electron acceptor most readily available for use by this first chemoautotroph would have been CO2. The most abundant electron donor may have been H2 that would have been outgassing from volcanoes at a rate estimated to be as large as 10(12) moles yr-1, as well as from photo-oxidation of Fe+2. We report here that certain methanogens will consume H2 down to partial pressures as low as 4 Pa (4 x 10(-5) atm) with CO2 as the sole carbon source at a rate of 0.7 ng H2 min-1 microgram-1 cell protein. The lower limit of pH2 for growth of methanogens can be understood on the basis that the pH2 needs to be high enough for one ATP to be synthesized per CO2 reduced. The pH2 values needed for growth measured here are consistent with those measured by Stevens and McKinley for growth of methanogens in deep basalt aquifers. H2-consuming autotrophs are likely to have had a profound effect on the chemistry of the early atmosphere and to have been a dominant sink for H2 on the early Earth after life began rather than escape from the Earth's atmosphere to space.

  15. The contribution of chemical abundances in nova ejecta to the interstellar medium

    NASA Astrophysics Data System (ADS)

    Li, Fanger; Zhu, Chunhua; Lü, Guoliang; Wang, Zhaojun

    2016-06-01

    According to the nova model from Yaron et al. (2005, ApJ, 418, 794) and José and Hernanz (1998, ApJ, 494, 680), and using a Monte Carlo simulation method, we investigate the contribution of chemical abundances in nova ejecta to the interstellar medium (ISM) of the Galaxy. We find that the mass ejected from classical novae is about 2.7 × 10-3 M⊙ yr-1. In the nova ejecta, the isotopic ratios of C, N, and O, that is, 13C/12C, 15N/14N, and 17O/16O, are higher by about one order of magnitude than those in red giants. We estimate that about 10%, 5%, and 20% of 13C, 15N, and 17O in the ISM of the Galaxy come from nova ejecta, respectively. However, the chemical abundances of C, N, and O calculated by our model cannot cover all observational values. This means that there is still a long way to go to understand novae.

  16. Quasar outflows and AGN feedback in the extreme UV: HST/COS observations of HE 0238-1904

    NASA Astrophysics Data System (ADS)

    Arav, Nahum; Borguet, Benoit; Chamberlain, Carter; Edmonds, Doug; Danforth, Charles

    2013-12-01

    Spectroscopic observations of quasar outflows at rest-frame 500-1000 Å have immense diagnostic power. We present analyses of such data, where absorption troughs from O IV and O IV* allow us to obtain the distance of the outflows from the AGN and troughs from Ne VIII and Mg X reveal the warm absorber phase of the outflow. Their inferred column densities, combined with those of O VI, N IV and H I, yield two important results. (1) The outflow shows two ionization phases, where the high-ionization phase carries the bulk of the material. This is similar to the situation seen in X-ray warm absorber studies. Furthermore, the low-ionization phase is inferred to have a volume filling factor of 10-5-10-6. (2) We determine a distance of 3000 pc from the outflow to the central source using the O IV*/O IV column density ratio and the knowledge of the ionization parameter. Since this is a typical high-ionization outflow, we can determine robust values for the outflow's mass flux and kinetic luminosity of 40 M⊙ yr-1 and 1045 erg s-1, respectively, where the latter is roughly equal to 1 per cent of the bolometric luminosity. Such a large kinetic luminosity and mass flow rate measured in a typical high-ionization wind suggest that quasar outflows are a major contributor to AGN feedback mechanisms.

  17. Can Direct Collapse Black Holes Launch Gamma-Ray Bursts and Grow to Supermassive Black Holes?

    NASA Astrophysics Data System (ADS)

    Matsumoto, Tatsuya; Nakauchi, Daisuke; Ioka, Kunihito; Heger, Alexander; Nakamura, Takashi

    2015-09-01

    The existence of black holes (BHs) of mass ˜ {10}9 {M}⊙ at z≳ 6 is a big puzzle in astrophysics because even optimistic estimates of the accretion time are insufficient for stellar-mass BHs of ˜ 10 {M}⊙ to grow into such supermassive BHs. A resolution of this puzzle might be the direct collapse of supermassive stars with mass M˜ {10}5 {M}⊙ into massive seed BHs. We find that if a jet is launched from the accretion disk around the central BH, the jet can break out of the star because of the structure of the radiation-pressure-dominated envelope. Such ultralong gamma-ray bursts with duration of ˜ {10}4-106 s and flux of 10-11-10-8 erg s-1 cm-2 could be detectable by Swift. We estimate an event rate of ≲ 1 {{yr}}-1. The total explosion energy is ≳1055-{10}56 {erg}. The resulting negative feedback delays the growth of the remnant BH by about 70 {Myr} or evacuates the host galaxy completely.

  18. Multiwavelength modeling the SED of supersoft X-ray sources. II. RS Ophiuchi: From the explosion to the SSS phase

    NASA Astrophysics Data System (ADS)

    Skopal, A.

    2015-04-01

    RS Oph is a recurrent symbiotic nova that undergoes nova-like outbursts on a time scale of 20 yr. Its two last eruptions (1985 and 2006) were subject of intensive multiwavelengths observational campaign from the X-rays to the radio. This contribution aims to determine physical parameters and the ionization structure of the nova from its explosion to the first emergence of the supersoft X-rays (day 26) by using the method of multiwavelength modeling the SED. From the very beginning of the eruption, the model SED revealed the presence of both a strong stellar and nebular component of radiation in the spectrum. During the first 4 days, the nova evinced a biconical ionization structure. The ∼8200 K warm and 160-200 R⊙ extended pseudophotosphere encompassed the white dwarf (WD) around its equator to the latitude > 40 ° . The remaining space around the WD's poles was ionized, producing a strong nebular continuum with the emission measure EM ∼ 2.3 ×1062 cm-3 via the fast wind from the WD. The luminosity of the burning WD was highly super-Eddington for the whole investigated period. The wind mass loss at rates of 10-4-10-5M⊙yr-1 and the presence of jets suggest an accretion throughout a disk at a high rate, which can help to sustain the super-Eddington luminosity of the accretor for a long time.

  19. Dormant comets among the near-Earth object population: a meteor-based survey

    NASA Astrophysics Data System (ADS)

    Ye, Quan-Zhi; Brown, Peter G.; Pokorný, Petr

    2016-11-01

    Dormant comets in the near-Earth object (NEO) population are thought to be involved in the terrestrial accretion of water and organic materials. Identification of dormant comets is difficult as they are observationally indistinguishable from their asteroidal counterparts, however, they may have produced dust during their final active stages which potentially are detectable today as weak meteor showers at the Earth. Here we present the result of a reconnaissance survey looking for dormant comets using 13 567 542 meteor orbits measured by the Canadian Meteor Orbit Radar (CMOR). We simulate the dynamical evolution of the hypothetical meteoroid streams originated from 407 near-Earth asteroids in cometary orbits that resemble orbital characteristics of Jupiter-family comets (JFCs). Out of the 44 hypothetical showers that are predicted to be detectable by CMOR, we identify five positive detections that are statistically unlikely to be chance associations, including three previously known associations. This translates to a lower limit to the dormant comet fraction of 2.0 ± 1.7 per cent in the NEO population and a dormancy rate of ˜10-5 yr-1 per comet. The low dormancy rate confirms disruption and dynamical removal as the dominant end state for near-Earth JFCs. We also predict the existence of a significant number of meteoroid streams whose parents have already been disrupted or dynamically removed.

  20. A closer look at the Canarias Einstein ring

    NASA Astrophysics Data System (ADS)

    Lee (), Chien-Hsiu

    2016-11-01

    Following the recently discovery of the Canarias Einstein ring by Bettinelli et al., we present further studies of this system. Searching the DECam data archive, we found i-band images of this system, in additional to the g-, and r-band images presented in Bettinelli et al. Using GALFIT, we are able to model the lens light contribution and derive the lens colour, g - r = 2.27 and r - i = 0.70 mag, indicating that the lens is a luminous red galaxy. After subtracting the lens light, we use LENSVIEW to model the Einstein ring image and obtain an angular Einstein radius of 2.25 arcsec, which translates into an enclosed lens mass of 2.02 × 1012 M⊙ and a velocity dispersion of 460 km s-1, assuming the lens has a singular isothermal ellipsoid mass profile. The best-fitting model yields a total magnification of 10.5 and enables us to derive the un-lensed star formation rate of the source to be ˜8 M⊙ yr-1.

  1. Multi-interferogram method for measuring interseismic deformation: Denali Fault, Alaska

    USGS Publications Warehouse

    Biggs, Juliet; Wright, Tim; Lu, Zhong; Parsons, Barry

    2007-01-01

    Studies of interseismic strain accumulation are crucial to our understanding of continental deformation, the earthquake cycle and seismic hazard. By mapping small amounts of ground deformation over large spatial areas, InSAR has the potential to produce continental-scale maps of strain accumulation on active faults. However, most InSAR studies to date have focused on areas where the coherence is relatively good (e.g. California, Tibet and Turkey) and most analysis techniques (stacking, small baseline subset algorithm, permanent scatterers, etc.) only include information from pixels which are coherent throughout the time-span of the study. In some areas, such as Alaska, where the deformation rate is small and coherence very variable, it is necessary to include information from pixels which are coherent in some but not all interferograms. We use a three-stage iterative algorithm based on distributed scatterer interferometry. We validate our method using synthetic data created using realistic parameters from a test site on the Denali Fault, Alaska, and present a preliminary result of 10.5 ?? 5.0 mm yr-1 for the slip rate on the Denali Fault based on a single track of radar data from ERS1/2. ?? 2007 The Authors Journal compilation ?? 2007 RAS.

  2. Detecting leaks in gas-filled pressure vessels using acoustic resonances.

    PubMed

    Gillis, K A; Moldover, M R; Mehl, J B

    2016-05-01

    We demonstrate that a leak from a large, unthermostatted pressure vessel into ambient air can be detected an order of magnitude more effectively by measuring the time dependence of the ratio p/f(2) than by measuring the ratio p/T. Here f is the resonance frequency of an acoustic mode of the gas inside the pressure vessel, p is the pressure of the gas, and T is the kelvin temperature measured at one point in the gas. In general, the resonance frequencies are determined by a mode-dependent, weighted average of the square of the speed-of-sound throughout the volume of the gas. However, the weighting usually has a weak dependence on likely temperature gradients in the gas inside a large pressure vessel. Using the ratio p/f(2), we measured a gas leak (dM/dt)/M ≈ - 1.3 × 10(-5) h(-1) = - 0.11 yr(-1) from a 300-liter pressure vessel filled with argon at 450 kPa that was exposed to sunshine-driven temperature and pressure fluctuations as large as (dT/dt)/T ≈ (dp/dt)/p ≈ 5 × 10(-2) h(-1) using a 24-hour data record. This leak could not be detected in a 72-hour record of p/T. (Here M is the mass of the gas in the vessel and t is the time.). PMID:27250456

  3. An estimate of the terrestrial carbon budget of Russia using inventory based, eddy covariance and inversion methods

    NASA Astrophysics Data System (ADS)

    Dolman, A. J.; Shvidenko, A.; Schepaschenko, D.; Ciais, P.; Tchebakova, N.; Chen, T.; van der Molen, M. K.; Belelli Marchesini, L.; Maximov, T. C.; Maksyutov, S.; Schulze, E.-D.

    2012-06-01

    We determine the carbon balance of Russia, including Ukraine, Belarus and Kazakhstan using inventory based, eddy covariance, Dynamic Global Vegetation Models (DGVM), and inversion methods. Our current best estimate of the net biosphere to atmosphere flux is -0.66 Pg C yr-1. This sink is primarily caused by forests that using two independent methods are estimated to take up -0.69 Pg C yr-1. Using inverse models yields an average net biopshere to atmosphere flux of the same value with a interannual variability of 35 % (1σ). The total estimated biosphere to atmosphere flux from eddy covariance observations over a limited number of sites amounts to -1 Pg C yr-1. Fires emit 137 to 121 Tg C yr-1 using two different methods. The interannual variability of fire emissions is large, up to a factor 0.5 to 3. Smaller fluxes to the ocean and inland lakes, trade are also accounted for. Our best estimate for the Russian net biosphere to atmosphere flux then amounts to -659 Tg C yr-1 as the average of the inverse models of -653 Tg C yr-1, bottom up -563 Tg C yr-1 and the independent landscape approach of -761 Tg C yr-1. These three methods agree well within their error bounds, so there is good consistency between bottom up and top down methods. The best estimate of the net land to atmosphere flux, including the fossil fuel emissions is -145 to -73 Tg C yr-1. Estimated methane emissions vary considerably with one inventory-based estimate providing a net land to atmosphere flux of 12.6 Tg C-CH4yr -1 and an independent model estimate for the boreal and Arctic zones of Eurasia of 27.6 Tg C-CH4 yr-1.

  4. The modelled surface mass balance of the Antarctic Peninsula at 5.5 km horizontal resolution

    NASA Astrophysics Data System (ADS)

    van Wessem, J. M.; Ligtenberg, S. R. M.; Reijmer, C. H.; van de Berg, W. J.; van den Broeke, M. R.; Barrand, N. E.; Thomas, E. R.; Turner, J.; Wuite, J.; Scambos, T. A.; van Meijgaard, E.

    2016-02-01

    This study presents a high-resolution (˜ 5.5 km) estimate of surface mass balance (SMB) over the period 1979-2014 for the Antarctic Peninsula (AP), generated by the regional atmospheric climate model RACMO2.3 and a firn densification model (FDM). RACMO2.3 is used to force the FDM, which calculates processes in the snowpack, such as meltwater percolation, refreezing and runoff. We evaluate model output with 132 in situ SMB observations and discharge rates from six glacier drainage basins, and find that the model realistically simulates the strong spatial variability in precipitation, but that significant biases remain as a result of the highly complex topography of the AP. It is also clear that the observations significantly underrepresent the high-accumulation regimes, complicating a full model evaluation. The SMB map reveals large accumulation gradients, with precipitation values above 3000 mm we yr-1 in the western AP (WAP) and below 500 mm we yr-1 in the eastern AP (EAP), not resolved by coarser data sets such as ERA-Interim. The average AP ice-sheet-integrated SMB, including ice shelves (an area of 4.1 × 105 km2), is estimated at 351 Gt yr-1 with an interannual variability of 58 Gt yr-1, which is dominated by precipitation (PR) (365 ± 57 Gt yr-1). The WAP (2.4 × 105 km2) SMB (276 ± 47 Gt yr-1), where PR is large (276 ± 47 Gt yr-1), dominates over the EAP (1.7 × 105 km2) SMB (75 ± 11 Gt yr-1) and PR (84 ± 11 Gt yr-1). Total sublimation is 11 ± 2 Gt yr-1 and meltwater runoff into the ocean is 4 ± 4 Gt yr-1. There are no significant trends in any of the modelled AP SMB components, except for snowmelt that shows a significant decrease over the last 36 years (-0.36 Gt yr-2).

  5. Responses of streams in central Appalachian Mountain region to reduced acidic deposition--comparisons with other regions in North America and Europe.

    PubMed

    Chen, Yushun; Lin, Lian-Shin

    2009-03-15

    Data from 5 wet deposition stations and 21 streams during 1980-2006 were analyzed to investigate chemical responses of streams to reduced acidic deposition in the central Appalachian Mountain region of West Virginia, USA. Wet deposition of acidic anions (i.e., sulfate, nitrate, and chloride) and hydrogen ions decreased significantly during the studied time period. Stream sulfate showed a delayed response to the reduced acidic deposition, and showed a decrease in the 2000s (-5.54 microeq L(-1) yr(-1)) and the whole period (-0.49 microeq L(-1) yr(-1)). No significant trend of stream nitrate+nitrite and chloride was observed. Stream alkalinity increased in the 1990s (+23.33 microeq L(-1) yr(-1)) and the whole period (+7.26 microeq L(-1) yr(-1)). Stream hydrogen ions decreased in the 1990s (-0.002 microeq L(-1) yr(-1)), 2000s (-0.001 microeq L(-1) yr(-1)), and the whole period (-0.001 microeq L(-1) yr(-1)). Compared with most acidic streams and lakes in the United States and Europe, a lower decreasing rate of hydrogen ions and higher increasing rate of alkalinity were observed in the alkaline West Virginian streams in the 1990s. However, due to their initial negative or zero alkalinity values, those acidic streams showed a higher percent increase in alkalinity than that in the alkaline West Virginian streams (from 800 microeq L(-1) yr(-1) to 1200 microeq L(-1) yr(-1)). Total aluminum in the West Virginian streams decreased in the 1990s (-0.67 micromol L(-1) yr(-1)) and the whole period (-0.22 micromol L(-1) yr(-1)). The current study advanced our understanding of streams' responses to the reduced acidic deposition in the Mid-Appalachians since the passage of the 1970 and 1990 Amendments to the United States Clean Air Act (US CAAA).

  6. Energy levels in Ag-like (4d{sup 10}4f, 4d{sup 10}5l (l = 0-3)), Pd-like (4d{sup 9}4f [J = 1], 4d{sup 9}5p [J = 1], 4d{sup 9}5f [J = 1]), and Rh-like (4d{sup 9} [J = 5/2, 3/2]) ions with Z {<=} 86

    SciTech Connect

    Ivanova, E.P.

    2009-11-15

    Relativistic perturbation theory with a model potential is used for the calculation of energy levels of the states 4f{sub 5/2}, 4f{sub 7/2}, 5s{sub 1/2}, 5p{sub 1/2}, 5p{sub 3/2}, 5d{sub 3/2}, 5d{sub 5/2}, 5f{sub 5/2}, and 5f{sub 7/2} above the 1s{sup 2}2s{sup 2}2p{sup 6}3s{sup 2}3p{sup 6}3d{sup 10}4s{sup 2}4p{sup 6}4d{sup 10} core, with one vacancy 4d{sub 5/2}{sup 9}, 4d{sub 7/2}{sup 9} in the same core, in the silver and rhodium isoelectronic sequences with the maximum nuclear charge Z = 86. The method of extrapolation of the model potential parameter is applied to calculate one-electron and one-vacancy wavefunctions. The wavefunctions of Ag- and Rh-like ions were used to calculate the energies of resonance transitions to the ground state {sup 1}S{sub 0} in Pd-like ions. Good agreement between the theoretical and the experimental energies of the resonance transitions in Pd-like ions indicates the reliability of the results obtained.

  7. Nitrogen and phosphorus budget of a polyculture system of sea cucumber ( Apostichopus japonicus), jellyfish ( Rhopilema esculenta) and shrimp ( Fenneropenaeus chinensis)

    NASA Astrophysics Data System (ADS)

    Li, Junwei; Dong, Shuanglin; Gao, Qinfeng; Zhu, Changbo

    2014-06-01

    The nitrogen (N) and phosphorus (P) budget and the ecological efficiency of a polyculture system of sea cucumber ( Apostichopus japonicus), jellyfish ( Rhopilema esculenta) and shrimp ( Fenneropenaeus chinensis) were studied in a cofferdam, 120.2 ha in size. The nutrients were supplied by spring tide inflow. In total, 139600 kg N yr-1 and 9730 kg P yr-1 input to the system; while 118900 kg N yr-1 and 2840 kg P yr-1 outflowed from the system concurrently, thus the outflow was 85.7% (N) and 29.2% (P) of inflow. The production of N and P was 889.5 kg yr-1 and 49.28 kg yr-1 (sea cucumber) and 204 kg yr-1 and 18.03 kg yr-1 (jellyfish and shrimp), respectively. The utilization rate of N and P by polycultured animals was 7.8‰ and 6.9‰, respectively, 21.9% and 38% higher than that of monocultured sea cucumber. Our results indicated that the polyculture system was an efficient culture system of animals and a remediation system of coastal environment as well; it scavenged 14.3% and 70.8% of N and P, respectively. Such an ecological efficiency may be improved further by increasing either the stocking density or the size of sea cucumber or both.

  8. Nonsustainable groundwater sustaining irrigation: A global assessment

    NASA Astrophysics Data System (ADS)

    Wada, Yoshihide; van Beek, L. P. H.; Bierkens, Marc F. P.

    2012-06-01

    Water used by irrigated crops is obtained from three sources: local precipitation contributing to soil moisture available for root water uptake (i.e., green water), irrigation water taken from rivers, lakes, reservoirs, wetlands, and renewable groundwater (i.e., blue water), and irrigation water abstracted from nonrenewable groundwater and nonlocal water resources. Here we quantify globally the amount of nonrenewable or nonsustainable groundwater abstraction to sustain current irrigation practice. We use the global hydrological model PCR-GLOBWB to simulate gross crop water demand for irrigated crops and available blue and green water to meet this demand. We downscale country statistics of groundwater abstraction by considering the part of net total water demand that cannot be met by surface freshwater. We subsequently confront these with simulated groundwater recharge, including return flow from irrigation to estimate nonrenewable groundwater abstraction. Results show that nonrenewable groundwater abstraction contributes approximately 20% to the global gross irrigation water demand for the year 2000. The contribution of nonrenewable groundwater abstraction to irrigation is largest in India (68 km3 yr-1) followed by Pakistan (35 km3 yr-1), the United States (30 km3 yr-1), Iran (20 km3 yr-1), China (20 km3 yr-1), Mexico (10 km3 yr-1), and Saudi Arabia (10 km3 yr-1). Results also show that globally, this contribution more than tripled from 75 to 234 km3 yr-1 over the period 1960-2000.

  9. Rates and causes of recent global sea-level rise inferred from long tide gauge data records

    NASA Astrophysics Data System (ADS)

    Nakada, Masao; Inoue, Hiroshi

    2005-05-01

    Tide gauge data at seven sites of the Permanent Service for Mean Sea Level (PSMSL), with information for relative sea-level during the past 140-200 yr, were analyzed to examine the rates and causes of the global sea-level rise (GSLR) during the twentieth century. By subtracting linear trends for relative sea-level rise during the past 100 yr from the observed data, we get the apparent GSLRs of ˜1 mm yr -1 for five sites around the Baltic Sea and Brest. The rate for San Francisco is significantly larger than this, with an optimum value ˜2 mm yr -1. The spatial difference of ˜1 mm yr -1 between these sites is reasonably explained by the recent melting of the Greenland ice sheet with an equivalent sea-level rise of ˜1 mm yr -1. The predicted relative sea-level change for this melting scenario is 0.5 mm yr -1 at sites around the Baltic Sea and Brest, and 1.5 mm yr -1 for San Francisco. The residuals between observations and predictions, ˜0.5 mm yr -1 at all sites, may be contributed by thermal expansion of seawater and/or other melting sources. These results suggest the rate of twentieth-century GSLR to be 1.5 mm yr -1.

  10. IDENTIFYING DISCHARGE ZONES OF ARSENIC IN THE GOOSE RIVER BASIN, MAINE

    EPA Science Inventory

    Groundwater discharge areas are simulated from water balance modeling and kriging of oxygen isotopes in groundwater within the Goose River basin. Groundwater fluxes of discharge range from -10 cm yr-1 to < -25 cm yr-1 and are associated with areas of elevated arsenic in wells. De...

  11. Monte Carlo Population Synthesis of Post-common-envelope White Dwarf Binaries and Type Ia supernova Rate

    NASA Astrophysics Data System (ADS)

    Ablimit, Iminhaji; Maeda, Keiichi; Li, Xiang-Dong

    2016-07-01

    Binary population synthesis (BPS) studies provide a comprehensive way to understand the evolution of binaries and their end products. Close white dwarf (WD) binaries have crucial characteristics for examining the influence of unresolved physical parameters on binary evolution. In this paper, we perform Monte Carlo BPS simulations, investigating the population of WD/main-sequence (WD/MS) binaries and double WD binaries using a publicly available binary star evolution code under 37 different assumptions for key physical processes and binary initial conditions. We considered different combinations of the binding energy parameter (λ g: considering gravitational energy only; λ b: considering both gravitational energy and internal energy; and λ e: considering gravitational energy, internal energy, and entropy of the envelope, with values derived from the MESA code), CE efficiency, critical mass ratio, initial primary mass function, and metallicity. We find that a larger number of post-CE WD/MS binaries in tight orbits are formed when the binding energy parameters are set by λ e than in those cases where other prescriptions are adopted. We also determine the effects of the other input parameters on the orbital periods and mass distributions of post-CE WD/MS binaries. As they contain at least one CO WD, double WD systems that evolved from WD/MS binaries may explode as type Ia supernovae (SNe Ia) via merging. In this work, we also investigate the frequency of two WD mergers and compare it to the SNe Ia rate. The calculated Galactic SNe Ia rate with λ = λ e is comparable to the observed SNe Ia rate, ˜8.2 × 10-5 yr-1 - ˜4 × 10-3 yr-1 depending on the other BPS parameters, if a DD system does not require a mass ratio higher than ˜0.8 to become an SNe Ia. On the other hand, a violent merger scenario, which requires the combined mass of two CO WDs ≥ 1.6M ⊙ and a mass ratio >0.8, results in a much lower SNe Ia rate than is observed.

  12. Early and late time VLT spectroscopy of SN 2001el - progenitor constraints for a type Ia supernova

    NASA Astrophysics Data System (ADS)

    Mattila, S.; Lundqvist, P.; Sollerman, J.; Kozma, C.; Baron, E.; Fransson, C.; Leibundgut, B.; Nomoto, K.

    2005-11-01

    We present early time high-resolution (VLT/UVES) and late time low-resolution (VLT/FORS) optical spectra of the normal type Ia supernova, SN 2001el. The high-resolution spectra were obtained 9 and 2 days before (B-band) maximum light. This was in order to allow the detection of narrow hydrogen and/or helium emission lines from the circumstellar medium of the supernova. No such lines were detected in our data. We therefore use these spectra together with photoionisation models to derive upper limits of 9×10-6 {M}_⊙ yr-1 and 5×10-5 {M}_⊙ yr-1 for the mass loss rate from the progenitor system of SN 2001el assuming velocities of 10 km s-1 and 50 km s-1, respectively, for a wind extending to outside at least a few × 1015 cm away from the supernova explosion site. So far, these are the best Hα based upper limits obtained for a type Ia supernova, and exclude a symbiotic star in the upper mass loss rate regime (so called Mira type stars) from being the progenitor of SN 2001el. The low-resolution spectrum was obtained in the nebular phase of the supernova, 400 days after the maximum light, to search for any hydrogen rich gas originating from the supernova progenitor system. However, we see no signs of Balmer lines in our spectrum. Therefore, we model the late time spectra to derive an upper limit of 0.03 M⊙ for solar abundance material present at velocities lower than 1000 km s-1 within the supernova explosion site. According to numerical simulations of Marietta et al. (2000) this is less than the expected mass lost by a subgiant, red giant or a main-sequence secondary star at a small binary separation as a result of the SN explosion. Our data therefore exclude these scenarios as the progenitor of SN 2001el. Finally, we discuss the origin of high velocity Ca II lines previously observed in a few type Ia supernovae before the maximum light. We see both the Ca II IR triplet and the H&K lines in our earliest (-9 days) spectrum at a very high velocity of up to 34 000

  13. Possible Solution of the Long-standing Discrepancy in the Microlensing Optical Depth toward the Galactic Bulge by Correcting the Stellar Number Count

    NASA Astrophysics Data System (ADS)

    Sumi, T.; Penny, M. T.

    2016-08-01

    We find that significant incompleteness in stellar number counts results in a significant overestimate of the microlensing optical depth τ and event rate per star per year Γ toward the Galactic bulge from the first two years of the MOA-II survey. We find that the completeness in red clump giant (RCG) counts {f}{{RC}} decreases proportional to the galactic latitude b, as {f}{{RC}}=(0.63+/- 0.11)-(0.052+/- 0.028)× b, ranging between 1 and 0.7 at b=-6^\\circ ˜ -1\\buildrel{\\circ}\\over{.} 5. The previous measurements using all sources by difference image analysis (DIA) by MACHO and MOA-I suffer the same bias. On the other hand, the measurements using an RCG sample by OGLE-II, MACHO, and EROS were free from this bias because they selected only the events associated with the resolved stars. Thus, the incompleteness both in the number of events and stellar number count cancel out. We estimate τ and Γ by correcting this incompleteness. In the central fields with | l| \\lt 5^\\circ , we find {{Γ }}=[18.74+/- 0.91]× {10}-6\\exp [(0.53+/- 0.05)(3-| b| )] star-1 yr-1 and {τ }200=[1.84+/- 0.14]× {10}-6\\exp [(0.44+/- 0.07)(3-| b| )] for the 427 events with {t}{{E}}≤slant 200 days using all sources brighter than {I}s≤slant 20 mag. Our revised all-source τ measurements are about 2σ smaller than the other all-source measurements and are consistent with the RCG measurements within 1σ. We conclude that the long-standing problem on discrepancy between the high τ with all-source samples by DIA and low τ with RCG samples can probably be explained by the incompleteness of the stellar number count. A model fit to these measurements predicts {{Γ }}=4.60+/- 0.25× {10}-5 star-1 yr-1 at | b| ˜ -1\\buildrel{\\circ}\\over{.} 4 and -2\\buildrel{\\circ}\\over{.} 25\\lt l\\lt 3\\buildrel{\\circ}\\over{.} 75 for sources with I\\lt 20, where the future space mission, Wide Field Infrared Space Telescope, will observe.

  14. Drought effects on soil CO

    NASA Astrophysics Data System (ADS)

    van Straaten, O.; Veldkamp, E.; Köhler, M.; Anas, I.

    2009-12-01

    Climate change induced droughts pose a serious threat to ecosystems across the tropics and sub-tropics, particularly to those areas not adapted to natural dry periods. In order to study the vulnerability of cacao (Theobroma cacao) - Gliricidia sepium agroforestry plantations to droughts a large scale throughfall displacement roof was built in Central Sulawesi, Indonesia. In this 19-month replicated experiment, we measured soil surface CO2 efflux (soil respiration) in three simulated drought plots compared with three adjacent control plots. Soil respiration rates peaked at intermediate soil moisture and decreased under increasingly dry conditions (drought induced), but also decreased when soils became water saturated, as evidenced in control plots. The simulated drought plots exhibited a slight decrease in soil respiration compared to the control plots (average 13% decrease). The strength of the drought effect was spatially variable - while some measurement chamber sites reacted strongly ("responsive") to the decrease in soil water content (up to R2=0.70) (n=11), others did not react at all ("non-responsive") (n=7). The degree of soil CO2 respiration drought response was highest around cacao tree stems and decreased with distance from the stem (R2=0.22). A significant correlation was measured between "responsive" soil respiration chamber sites and sap flux density ratios of cacao (R=0.61) and Gliricidia (R=0.65). Leaf litter CO2 respiration decreased as conditions became drier. During dry periods the litter layer contributed approximately 3-4% of the total CO2 efflux and up to 40% during wet periods. A CO2 flush was recorded during the rewetting phase that lasted for approximately two weeks, during which time accumulated labile carbon stocks mineralized. The net effect on soil CO2 emissions over the duration of the experiment was neutral, control plots respired 11.1±0.5 Mg C ha-1 yr-1, while roof plots respired 10.5±0.5 Mg C ha-1 yr-1.

  15. A new estimation of global soil greenhouse gas fluxes using a simple data-oriented model.

    PubMed

    Hashimoto, Shoji

    2012-01-01

    Soil greenhouse gas fluxes (particularly CO(2), CH(4), and N(2)O) play important roles in climate change. However, despite the importance of these soil greenhouse gases, the number of reports on global soil greenhouse gas fluxes is limited. Here, new estimates are presented for global soil CO(2) emission (total soil respiration), CH(4) uptake, and N(2)O emission fluxes, using a simple data-oriented model. The estimated global fluxes for CO(2) emission, CH(4) uptake, and N(2)O emission were 78 Pg C yr(-1) (Monte Carlo 95% confidence interval, 64-95 Pg C yr(-1)), 18 Tg C yr(-1) (11-23 Tg C yr(-1)), and 4.4 Tg N yr(-1) (1.4-11.1 Tg N yr(-1)), respectively. Tropical regions were the largest contributor of all of the gases, particularly the CO(2) and N(2)O fluxes. The soil CO(2) and N(2)O fluxes had more pronounced seasonal patterns than the soil CH(4) flux. The collected estimates, including both the previous and the present estimates, demonstrate that the means of the best estimates from each study were 79 Pg C yr(-1) (291 Pg CO(2) yr(-1); coefficient of variation, CV = 13%, N = 6) for CO(2), 21 Tg C yr(-1) (29 Tg CH(4) yr(-1); CV = 24%, N = 24) for CH(4), and 7.8 Tg N yr(-1) (12.2 Tg N(2)O yr(-1); CV = 38%, N = 11) for N(2)O. For N(2)O, the mean of the estimates that was calculated by excluding the earliest two estimates was 6.6 Tg N yr(-1) (10.4 Tg N(2)O yr(-1); CV = 22%, N = 9). The reported estimates vary and have large degrees of uncertainty but their overall magnitudes are in general agreement. To further minimize the uncertainty of soil greenhouse gas flux estimates, it is necessary to build global databases and identify key processes in describing global soil greenhouse gas fluxes.

  16. Changes in ground-level PM mass concentration and column aerosol optical depth over East Asia during 2004-2014

    NASA Astrophysics Data System (ADS)

    Nam, J.; Kim, S. W.; Park, R.; Yoon, S. C.; Sugimoto, N.; Park, J. S.; Hong, J.

    2015-12-01

    Multi-year records of moderate resolution imaging spectroradiometer (MODIS), ground-level particulate matter (PM) mass concentration, cloud-aerosol lidar with orthogonal polarization (CALIOP), and ground-level lidar were analyzed to investigate seasonal and annual changes of aerosol optical depth (AOD) and PM mass concentration over East Asia. Least mean square fit method is applied to detect the trends and their magnitudes for each selected regions and stations. Eleven-year MODIS measurements show generally increasing trends in both AOD (1.18 % yr-1) and Ångström exponent (0.98 % yr-1), especially over the east coastal industrialized region in China. Monthly variation of AOD show maximum value at April-July, which were related to the progress of summer monsoon rain band and stationary continental air mass on the northeast of Asia. Increasing trends of AOD were found for eight cites in China (0.80 % yr-1) and Seoul site, Korea (0.40 % yr-1), whereas no significant change were shown in Gosan background site (0.04 % yr-1) and decreasing trend at five background sites in Japan (-0.42 % yr-1). Contrasting to AOD trend, all fifteen sites in China (-1.28 % yr-1), Korea (-2.77 % yr-1), and Japan (-2.03 % yr-1) showed decreasing trend of PM10 mass concentration. Also, PM2.5 mass concentration at Beijing, Seoul, Rishiri, and Oki show significant decreasing trend of -1.16 % yr-1. To further discuss the opposite trend of surface PM mass concentration and column AOD, we investigate vertical aerosol profile from lidar measurements. AOD estimated for planetary boundary layer (surface~1.5 km altitude; AODPBL) from CALIOP measurements over East China show decreasing trend of -1.71 % yr-1 over the period of 2007-2014, wherever AOD estimated for free troposphere (1.5 km~5 km altitude; AODFT) show increasing trend of 2.92 % yr-1. In addition, ground-level lidar measurements in Seoul show decreasing AODPBL trend of -2.57 % yr-1, whereas, AODFT show no significant change (-0.44 % yr

  17. The modelled surface mass balance of the Antarctic Peninsula at 5.5 km horizontal resolution

    NASA Astrophysics Data System (ADS)

    van Wessem, J. M.; Ligtenberg, S. R. M.; Reijmer, C. H.; van de Berg, W. J.; van den Broeke, M. R.; Barrand, N. E.; Thomas, E. R.; Turner, J.; Wuite, J.; Scambos, T. A.; van Meijgaard, E.

    2015-09-01

    This study presents a high-resolution (~ 5.5 km) estimate of Surface Mass Balance (SMB) over the period 1979-2014 for the Antarctic Peninsula (AP), generated by the regional atmospheric climate model RACMO2.3 and a Firn Densification Model (FDM). RACMO2.3 is used to force the FDM, which calculates processes in the snowpack, such as meltwater percolation, refreezing and runoff. We evaluate model output with 132 in-situ SMB observations and discharge rates from 6 glacier drainage basins, and find that the model realistically simulates the strong spatial variability in precipitation, but that significant biases remain as a result of the highly complex topography of the AP. It is also clear that the observations significantly underrepresent the high-accumulation regimes. The SMB map reveals large accumulation gradients, with precipitation values above 3000 mm we yr-1 over the western AP (WAP) and below 500 mm we yr-1 on the eastern AP (EAP), not resolved by coarser data-sets such as ERA-Interim. The other SMB components are one order of magnitude smaller, with drifting snow sublimation the largest ablation term removing up to 100 mm we yr-1 of mass. Snowmelt is widespread over the AP, reaching 500 mm we yr-1 towards the northern ice shelves, but the meltwater mostly refreezes. As a result runoff fluxes are low, but still considerable (200 mm we yr-1) over the Larsen (B/C), Wilkins and George VI ice shelves. The average AP ice sheet integrated SMB, including ice shelves (an area of 4.1 × 105 km2), is estimated at 351 Gt yr-1 with an interannual variability of 58 Gt yr-1, which is dominated by precipitation (PR) (365 ± 57 Gt yr-1). The WAP (2.4 × 105 km2) SMB (276 ± 47 Gt yr-1), where PR is large (276 ± 47 Gt yr-1), dominates over the EAP (1.7 × 105 km2) SMB (75 ± 11 Gt yr-1) and PR (84 ± 11 Gt yr-1). Total sublimation is 11 ± 2 Gt yr-1 and meltwater runoff into the ocean is 4 ± 4 Gt yr-1. There are no significant trends in any of the AP SMB components, except

  18. Radiocesium wash-off associated with soil erosion from various land uses after the Fukushima Dai-ichi NPP accident

    NASA Astrophysics Data System (ADS)

    Wakiyama, Yoshifumi; Onda, Yuichi; Yoshimura, Kazuya; Kato, Hiroaki; Konoplev, Alexei; Zheleznyak, Mark

    2014-05-01

    Soil erosion is the initial process which drives radiocesium into the aquatic systems and therefore the quantification of radiocesium wash-off associated with soil erosion is indispensable for mitigating the risks. This study presents two year's observation of soil erosion and radiocesium wash-off to quantify differences in radiocesium behavior in various land uses. Seven runoff plots were established in four landscapes; uncultivated farmland (Farmland A1, Farmland B1), cultivated farmland (Farmland A2, Farmland B2), grassland (Grassland A, Grassland B) and Japanese cedar forest (Forest) in Kawamata town, an area affected by the Fukushima Dai-ichi Nuclear Power Plant accident. The discharged sediments were collected approximately every two weeks. In laboratories, collected sediments were dried and weighed for calculating soil erosion rates (kg m-2) and served for measurements of radiocesium concentration (Bq kg-1) with HPGe detectors. The erosivity factor of the Universal Soil Loss Equation (R-factor: MJ mm ha-1 hr-1 yr-1) was calculated based on the data of precipitation. Standardized soil erosion rates (kg m-2 MJ-1 mm-1 ha hr yr), observed soil erosion rates divided by R-factor, was 1.8 × 10-4 in Farmland A1, 6.0 × 10-4 in Farmland A2, 1.5 × 10-3 in Farmland B1, 8.3 × 10-4 in Farmland B2, 9.6 × 10-6 in Grassland A, 5.9 × 10-6 in Grassland B and 2.3 × 10-6 in Forest. These erosion rates were basically proportional to their vegetation cover of soil surfaces except for cultivated farmlands. Concentrations of Cs-137 in eroded sediments basically depended on the local deposition of Cs-137 and varied enormously with ranging several orders of magnitude in all the landscapes. For the observation period of time decreasing trends in concentrations of Cs-137 in eroded sediments were not obvious. To compare these results with those of Chernobyl, we calculated normalized 'solid' wash-off coefficient (m2 g-1) with dividing the mean total concentration of Cs-137 in

  19. A large and persistent carbon sink in the World s forests

    SciTech Connect

    Pan, Yude; Birdsey, Richard A.; Fang, Jingyun; Houghton, Richard; Kauppi, Pekka; Kurz, Werner; Phillips, Oliver; Shvidenko, Anatoly; Lewis, Simon; Canadell, Josep; Ciais, Philippe; Jackson, Robert B; Pacala, Stephen; Mcguire, David; Piao, Shilong; Rautiainen, Aapo; Sitch, Stephen; Hayes, Daniel J

    2011-01-01

    The terrestrial carbon (C) sink has been large in recent decades, but its size and location remain uncertain. Using forest inventory data and long-term ecosystem C studies, we estimated a total forest sink of 2.4 0.4 Pg C yr 1 globally for 1990-2007. We also estimated a source of 1.3 0.7 Pg C yr 1 from tropical land-use change, consisting of a gross tropical deforestation emission of 2.9 0.5 Pg C yr 1 partially compensated by a C sink in tropical forest regrowth of 1.6 0.5 Pg C yr 1. Together, the fluxes comprise a net global forest sink of 1.1 0.8 Pg C yr 1, with tropical estimates having the largest uncertainties. This forest sink is equivalent in magnitude to the terrestrial sink deduced from fossil fuel emissions and constraints of ocean and atmospheric sinks.

  20. Global tropospheric ozone variations from 2003 to 2011 as seen by SCIAMACHY

    NASA Astrophysics Data System (ADS)

    Ebojie, F.; Burrows, J. P.; Gebhardt, C.; Ladstätter-Weißenmayer, A.; von Savigny, C.; Rozanov, A.; Weber, M.; Bovensmann, H.

    2016-01-01

    An analysis of the tropospheric ozone (O3) columns (TOCs) derived from SCIAMACHY limb-nadir-matching (LNM) observations during the period 2003-2011, focusing on global variations in TOC, is described. The changes are derived using a multivariate linear regression model. TOC shows changes of -0.2 ± 0.4, 0.3 ± 0.4, 0.1 ± 0.5 and 0.1 ± 0.2 % yr-1, which are not statistically significant at the 2σ level in the latitude bands 30-50° N, 20° S-0, 0-20° N and 50-30° S, respectively. Tropospheric O3 shows statistically significant increases over some regions of South Asia (1-3 % yr-1), the South American continent (up to 2 % yr-1), Alaska (up to 2 % yr-1) and around Congo in Africa (up to 2 % yr-1). Significant increase in TOC is determined off the continents including Australia (up to 2 % yr-1), Eurasia (1-3 % yr-1) and South America (up to 3 % yr-1). Significant decrease in TOC (up to -3 % yr-1) is observed over some regions of the continents of North America, Europe and South America. Over the oceanic regions including the Pacific, North Atlantic and Indian oceans, significant decreases in TOC (-1 to -3 % yr-1) were observed. In addition, the response of the El Niño-Southern Oscillation (ENSO) and quasi-biennial oscillation (QBO) to changes in TOC for the period 2003-2011 was investigated. The result shows extensive regions, mostly in the tropics and Northern Hemisphere extratropics, of significant ENSO responses to changes in TOC and a significant QBO response to TOC changes over some regions.

  1. Physical and biological characteristics of the pelagic system across Fram Strait to Kongsfjorden

    NASA Astrophysics Data System (ADS)

    Hop, Haakon; Falk-Petersen, Stig; Svendsen, Harald; Kwasniewski, Slawek; Pavlov, Vladimir; Pavlova, Olga; Søreide, Janne E.

    2006-10-01

    handful of amphipod species and the polar cod. The ice-associated biomass transport of ice-amphipods was calculated, based on the ice area transport, at about 3.55 × 10 6 ton wet weight per year or about 4.2 × 10 5 t C yr -1. This represents a large energy input to the Greenland Sea, but also a drain on the core population residing in the multi-year pack ice (MYI) in the Arctic Ocean. A continuous habitat loss of MYI due to climate warming will likely reduce dramatically the sympagic food source. The pelagic and sympagic food web structures were revealed by stable isotopes. The carbon sources of particulate organic matter (POM), being Ice-POM and Pelagic-POM, revealed different isotopic signals in the organisms of the food web, and also provided information about the sympagic-pelagic and pelagic-benthic couplings. The marine food web and energy pathways were further determined by fatty acid trophic markers, which to a large extent supported the stable isotope picture of the marine food web, although some discrepancies were noted, particularly with regard to predator-prey relationships of ctenophores and pteropods.

  2. Decadal variability in the oxygen inventory of North Atlantic subtropical underwater captured by sustained, long-term oceanographic time series observations

    NASA Astrophysics Data System (ADS)

    Montes, Enrique; Muller-Karger, Frank E.; Cianca, Andrés.; Lomas, Michael W.; Lorenzoni, Laura; Habtes, Sennai

    2016-03-01

    Historical observations of potential temperature (θ), salinity (S), and dissolved oxygen concentrations (O2) in the tropical and subtropical North Atlantic (0-500 m; 0-40°N, 10-90°W) were examined to understand decadal-scale changes in O2 in subtropical underwater (STUW). STUW is observed at four of the longest, sustained ocean biogeochemical and ecological time series stations, namely, the CArbon Retention In A Colored Ocean (CARIACO) Ocean Time Series Program (10.5°N, 64.7°W), the Bermuda Atlantic Time-series Study (BATS; 31.7°N, 64.2°W), Hydrostation "S" (32.1°N, 64.4°W), and the European Station for Time-series in the Ocean, Canary Islands (ESTOC; 29.2°N, 15.5°W). Observations over similar time periods at CARIACO (1996-2013), BATS (1988-2011), and Hydrostation S (1980-2013) show that STUW O2 has decreased approximately 0.71, 0.28, and 0.37 µmol kg-1 yr-1, respectively. No apparent change in STUW O2 was observed at ESTOC over the course of the time series (1994-2013). Ship observation data for the tropical and subtropical North Atlantic archived at NOAA National Oceanographic Data Center show that between 1980 and 2013, STUW O2 (upper ~300 m) declined 0.58 µmol kg-1 yr-1 in the southeastern Caribbean Sea (10-15°N, 60-70°W) and 0.68 µmol kg-1 yr-1 in the western subtropical North Atlantic (30-35°N, 60-65°W). A declining O2 trend was not observed in the eastern subtropical North Atlantic (25-30°N, 15-20°W) over the same period. Most of the observed O2 loss seems to result from shifts in ventilation associated with decreased wind-driven mixing and a slowing down of STUW formation rates, rather than changes in diffusive air-sea O2 gas exchange or changes in the biological oceanography of the North Atlantic. Variability of STUW O2 showed a significant relationship with the wintertime (January-March) Atlantic Multidecadal Oscillation index (AMO, R2 = 0.32). During negative wintertime AMO years trade winds are typically stronger between 10°N and 30

  3. WFPC2 Imaging of Dust Structures and Star Formation in the Disk-Halo Interface of Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Savage, Blair

    1999-07-01

    WFPC2 images of five edge-on spirals to study star formation and dusty interstellar clouds in the disk-halo interface of these galaxies. Ground-based and HST images of the nearby {9 Mpc} edge-on spiral NGC 891 show an unexpected web of hundreds of dust structures at heights 0.4 <= z <= 1.7 kpc {Howk & Savage 1997}. With masses >10^5-10^6 M{sun}, the more prominent extraplanar dust complexes may be sites of star formation at high-z, and there is evidence for H II regions associated with unresolved continuum sources far above the plane of NGC 891. We have established that such high-z dust features and H II regions are not unique to NGC 891. We propose to image five edge-on spiral galaxies {D 17 - 70 Mpc} with the WFPC2. The proposed BVI images will be used to identify sites of on- going star formation in the thick disks of these galaxies, all of which show evidence for high-z dust complexes, and with ground-based H Alpha images will be used to study the stellar content o f any such regions. The resolution and point-source sensitivity of the WFPC2 are crucial for studying these star-forming regions. We will also use these images to study interstellar matter in the thick disks of these galaxies with unprecedented detail and derive the fundamental properties of high-z dusty clouds-including sizes, extinctions, column densities, masses, and gravitational potential energies.

  4. The early gaseous and stellar mass assembly of Milky Way-type galaxy haloes

    NASA Astrophysics Data System (ADS)

    Hensler, Gerhard

    2015-08-01

    In cosmological simulations of Cold Dark Matter (CDM) structure formation a vast number of subhalos is expected around massive galaxies like the Milky Way (MW). These DM subhalos are filled with baryons, gas that forms stars very early as observed from the stellar populations in the MW satellite galaxies. Satellite galaxies evolve in the tidal field of their mature galaxy and suffer accretion to the major galaxy and their partly disruption. By this, their mass loss is expected to feed the galaxy halo with stars and gas.From the Via Lactea II simulations we select a massive DM halo with its satellite system which evolves in the simulations to a present-day MW-type galaxy. We follow its evolution from redshift 4.5 to 2.5, i.e. over almost 2 billion years of the most interesting epoch of mass assembly. A high mass resolution allows for even low-mass satellites down to 10^5 Msun, but limits their distance range to the innermost 240 satellites of the system only. The applied chemo-dynamical method includes star formation, stellar energetic and chemical feedback, and gas physical processes.After the onset of the simulation our models demonstrate the action of tidal effects and satellite merging on the star-formation rate of the satellites, their gas loss by means of hot-gas expansion, of ram-pressure and tidal stripping, and the tidal extraction of stars, leading to the formation of the stellar and gaseous galactic halo. We also analyze the evolution of the satellites’ mass function, their baryonic and DM mass distributions, chemical abundances, their compactness, their present-day appearance, etc. with respect to observations and present-day correlations.

  5. Moments of inertia for neutron and strange stars: Limits derived for the Crab pulsar

    NASA Astrophysics Data System (ADS)

    Bejger, M.; Haensel, P.

    2002-12-01

    Recent estimates of the properties of the Crab nebula are used to derive constraints on the moment of inertia, mass and radius of the pulsar. To this purpose, we employ an approximate formula combining these three parameters. Our ``empirical formula'' I =~ a(x) M R2, where x=(M/Msun) (km/R), is based on numerical results obtained for thirty theoretical equations of state of dense matter. The functions a(x) for neutron stars and strange stars are qualitatively different. For neutron stars aNS(x)=x/(0.1+2x) for x<=0.1 (valid for M>0.2 Msun) and aNS(x)={2/ 9}(1+5x) for x>0.1. For strange stars aSS(x)={2/ 5}(1+x) (not valid for strange stars with crust and M<0.1 Msun). We obtain also an approximate expression for the maximum moment of inertia Imax,45 =~ (-0.37 + 7.12* xmax) (Mmax/Msun)(RM_max/ {10 km})2, where I45 = I/1045 g* cm2, valid for both neutron stars and strange stars. Applying our formulae to the evaluated values of ICrab, we derive constraints on the mass and radius of the pulsar. { A very conservative evaluation of the expanding nebula mass, Mneb=2 Msun, yields MCrab>1.2 Msun and RCrab= 10-14 km. Setting the most recent evaluation (``central value'') Mneb=4.6 Msun rules out most of the existing equations of state, leaving only the stiffest ones: MCrab>1.9 Msun, RCrab= 14-15 km.

  6. Separated Fringe Packet Binary Star Astrometry at the CHARA Array - An Update

    NASA Astrophysics Data System (ADS)

    Ten Brummelaar, Theo; Farrington, C. D.; Mason, B. D.; Roberts, L. C.; Turner, N. H.

    2014-01-01

    When observed with optical long-baseline interferometers (OLBI), components of a binary star which are sufficiently separated such that their interferometric fringe packets do not overlap are referred to as Separated Fringe Packet (SFP) binaries. At the CHARA Array these `wide' binaries are in the range of a few tens of milliarcseconds and extend out into the regime of systems resolved by speckle interferometry at single, large-aperture telescopes. These SFP measurements can provide additional data for orbits lacking good phase coverage, help constrain elements of already established orbits, and locate new binaries in the under-sampled regime between the bounds of spectroscopic surveys and speckle interferometry. Unlike binary stars whose fringes overlap, a visibility calibration star is not needed, and the separation of the fringe packets can provide an accurate vector separation. We apply the SFP approach to Omega Andromeda, HD 178911, and Xi Cephei. For these systems we determine masses for the two components of 0.963+/-0.049 M_{sun}; and 0.860+/-0.051 M_{sun}; and an orbital parallax of 39.54+/-1.85 mas for Omega Andromeda, for HD 178911 masses of 0.802+/-0.055 M_{sun}; and 0.622+/-0.053 M_{sun}; with orbital parallax of 28.26+/-1.70 mas, and masses of 1.045+/-0.031 M_{sun}; and 0.408+/-0.066 M_{sun}; orbital parallax of 38.10+/-2.81 mas for Xi Cephei.

  7. On the observed mass distribution of compact stellar remnants in close binary systems and possible interpretations proposed for the time being

    NASA Astrophysics Data System (ADS)

    Sokolov, V. V.

    2016-06-01

    It turns out that accumulation of data during 40-years observational studies just emphasized a contrast between pulsars and black hole (BH) candidates in Galactic close binary stellar systems: (1) the mass spectrum of these degenerate stellar objects (or collapsars) shows an evident absence of objects with masses within the interval from 2M_(Sun) (with a first peak at about 1.4M_(Sun)) to approximately 6M_(Sun), (2) and in close binary stellar systems with a low-massive (about 0.6M_(Sun)) optical companion the most probable mass value (the peak in the mass distribution of BH candidates) turned out to be close to 6.7M_(Sun). This puzzle of discrete mass spectra of collapsars in close binary systems demands some solution and explanation in stellar evolution scenarios in connection with the core-collapse supernovae explosion mechanism and in context of a relation between supernovae and gamma-ray bursts. The collapsar strong field - an analogue of BH in General Relativity - is investigated in a totally non-metric, dynamical model of gravitational interaction theory, in which extremely compact objects of the masses M_Q approx.= 6.7M_(Sun) with a quark-gluon plasma bag of radius r^* = GM_Q/c^2 approx.= 10 km exist.

  8. An estimate of the terrestrial carbon budget of Russia using inventory-based, eddy covariance and inversion methods

    NASA Astrophysics Data System (ADS)

    Dolman, A. J.; Shvidenko, A.; Schepaschenko, D.; Ciais, P.; Tchebakova, N.; Chen, T.; van der Molen, M. K.; Belelli Marchesini, L.; Maximov, T. C.; Maksyutov, S.; Schulze, E.-D.

    2012-12-01

    We determine the net land to atmosphere flux of carbon in Russia, including Ukraine, Belarus and Kazakhstan, using inventory-based, eddy covariance, and inversion methods. Our high boundary estimate is -342 Tg C yr-1 from the eddy covariance method, and this is close to the upper bounds of the inventory-based Land Ecosystem Assessment and inverse models estimates. A lower boundary estimate is provided at -1350 Tg C yr-1 from the inversion models. The average of the three methods is -613.5 Tg C yr-1. The methane emission is estimated separately at 41.4 Tg C yr-1. These three methods agree well within their respective error bounds. There is thus good consistency between bottom-up and top-down methods. The forests of Russia primarily cause the net atmosphere to land flux (-692 Tg C yr-1 from the LEA. It remains however remarkable that the three methods provide such close estimates (-615, -662, -554 Tg C yr-1) for net biome production (NBP), given the inherent uncertainties in all of the approaches. The lack of recent forest inventories, the few eddy covariance sites and associated uncertainty with upscaling and undersampling of concentrations for the inversions are among the prime causes of the uncertainty. The dynamic global vegetation models (DGVMs) suggest a much lower uptake at -91 Tg C yr-1, and we argue that this is caused by a high estimate of heterotrophic respiration compared to other methods.

  9. Model calculated global, regional and megacity premature mortality due to air pollution

    NASA Astrophysics Data System (ADS)

    Lelieveld, J.; Barlas, C.; Giannadaki, D.; Pozzer, A.

    2013-03-01

    Air pollution by fine particulate matter (PM2.5) and ozone (O3) has increased strongly with industrialization and urbanization. We estimated the premature mortality rates and the years of human life lost (YLL) caused by anthropogenic PM2.5 and O3 in 2005 for epidemiological regions defined by the World Health Organization. We carried out high-resolution global model calculations to resolve urban and industrial regions in greater detail compared to previous work. We applied a health impact function to estimate premature mortality for people of 30 yr and older, using parameters derived from epidemiological cohort studies. Our results suggest that especially in large countries with extensive suburban and rural populations, air pollution-induced mortality rates have previously been underestimated. We calculate a global respiratory mortality of about 773 thousand yr-1 (YLL ≈ 5.2 million yr-1), 186 thousand yr-1 by lung cancer (YLL ≈ 1.7 million yr-1) and 2.0 million yr-1 by cardiovascular disease (YLL ≈ 14.3 million yr-1). The global mean per capita mortality caused by air pollution is about 0.1 % yr-1. The highest premature mortality rates are found in the Southeast Asia and Western Pacific regions (about 25% and 46% of the global rate, respectively) where more than a dozen of the most highly polluted megacities are located.

  10. Reactive nitrogen emissions from crop and livestock farming in India

    NASA Astrophysics Data System (ADS)

    Aneja, Viney P.; Schlesinger, William H.; Erisman, Jan Willem; Behera, Sailesh N.; Sharma, Mukesh; Battye, William

    2012-02-01

    The rapid increase in anthropogenic nitrogen emissions to the atmosphere is matter of concern for the environment, as these may lead to photochemical air pollution, reduced visibility, eutrophication of surface waters, changes in biodiversity, acid rain, stratospheric ozone depletion, and global warming. In this study, ambient emissions of reactive nitrogen (ammonia and nitrous oxide) from animal and crop farming are analyzed for the base year 2003. This objective was achieved by the systematic development of a spatially resolved emissions inventory on a Geographic Information System (GIS) platform. Emissions of ammonia (NH 3) and nitrous oxide (N 2O) were estimated: (i) from livestock; 1705 Gg/yr and 214 Gg yr -1 and (ii) fertilizer applications; 2697 Gg yr -1 and 326 Gg yr -1. These estimated emissions were compared and contrasted with global, U.S., and European emissions of reactive nitrogen; emissions from India were second only to China. From the spatially resolved emission inventory, it was observed that the state of Uttar Pradesh has the highest NH 3 emission (522 Gg yr -1) followed by the state of Maharashtra (425 Gg yr -1) both from animal and crop farming. Similarly the State of Uttar Pradesh has the highest N 2O emission (70 Gg yr -1) followed by the state of Maharashtra (47 Gg yr -1).

  11. Biogenic carbon fluxes from global agricultural production and consumption

    SciTech Connect

    Wolf, Julie; West, Tristram O.; Le Page, Yannick LB; Kyle, G. Page; Zhang, Xuesong; Collatz, George; Imhoff, Marc L.

    2015-10-01

    Quantification of biogenic carbon fluxes from agricultural lands is needed to generate comprehensive bottom-up estimates of net carbon exchange for global and regional carbon monitoring. We estimated global agricultural carbon fluxes associated with annual crop net primary production (NPP), harvested biomass, and consumption of biomass by humans and livestock. These estimates were combined for a single estimate of net carbon exchange (NCE) and spatially distributed to 0.05 degree resolution using MODIS satellite land cover data. Global crop NPP in 2011 was estimated at 5.25 ± 0.46 Pg C yr-1, of which 2.05 ± 0.05 Pg C yr-1 was harvested and 0.54 Pg C yr-1 was collected from crop residues for livestock fodder. Total livestock feed intake in 2011 was 2.42 ± 0.21 Pg C yr-1, of which 2.31 ± 0.21 Pg C yr-1 was emitted as CO2, 0.07 ± 0.01 Pg C yr-1 was emitted as CH4, and 0.04 Pg C yr-1 was contained within milk and egg production. Livestock grazed an estimated 1.27 Pg C yr-1 in 2011, which constituted 52.4% of total feed intake. Global human food intake was 0.57 ± 0.03 Pg C yr-1 in 2011, the majority of which is respired as CO2. Completed global cropland carbon budgets accounted for the ultimate use of ca. 80% of harvested biomass. The spatial distribution of these fluxes may be used for global carbon monitoring, estimation of regional uncertainty, and for use as input to Earth system models.

  12. Exchanges of sediment between the flood plain and channel of the Amazon River in Brazil

    USGS Publications Warehouse

    Dunne, T.; Mertes, L.A.K.; Meade, R.H.; Richey, J.E.; Forsberg, B.R.

    1998-01-01

    Sediment transport through the Brazilian sector of the Amazon River valley, a distance of 2010 km, involves exchanges between the channel and the flood plain that in each direction exceed the annual flux of sediment out of the river at O??bidos (???1200 Mt yr-1). The exchanges occur through bank erosion, bar deposition, settling from diffuse overbank flow, and sedimentation in flood-plain channels. We estimated the magnitude of these exchanges for each of 10 reaches of the valley, and combined them with calculations of sediment transport into and out of the reaches based on sediment sampling and flow records to define a sediment budget for each reach. Residuals in the sediment budget of a reach include errors of estimation and erosion or deposition within the channel. The annual supply of sediment entering the channel from bank erosion was estimated to average 1570 Mt yr-1 (1.3 ?? the O??bidos flux) and the amount transferred from channel transport to the bars (380 Mt yr-1) and the flood plain (460 Mt yr-1 in channelized flow; 1230 Mt yr-1 in diffuse overbank flow) totaled 2070 Mt yr-1 (1.7 ?? the O??bidos flux). Thus, deposition on the bars and flood plain exceeded bank erosion by 500 Mt yr-1 over a 10-16 yr period. Sampling and calculation of sediment loads in the channel indicate a net accumulation in the valley floor of approximately 200 Mt yr-1 over 16 yr, crudely validating the process-based calculations of the sediment budget, which in turn illuminate the physical controls on each exchange process. Another 300-400 Mt yr-1 are deposited in a delta plain downstream of O??bidos. The components of the sediment budget reflect hydrologie characteristics of the valley floor and geomorphic characteristics of the channel and flood plain, which in turn are influenced by tectonic features of the Amazon structural trough.

  13. Wheels of Fire. II. Neutral Hydrogen in the Cartwheel Ring Galaxy

    NASA Astrophysics Data System (ADS)

    Higdon, James L.

    1996-08-01

    The VLA was used to investigate the distribution and kinematics of neutral hydrogen, and the relation between massive star formation (MSF) and gas surface density, in the Cartwheel ring galaxy. Over 85% of the Cartwheel's H I resides in the outer ring, with a low surface density component filling much of the interior. Analysis of the H I velocity field indicates that the outer ring is expanding at V_exp_ = 53 +/- 9 km s^-1^, and that ~300 Myr have elapsed since the intruder's passage. Changes in V_exp_ with radius show that gas is beginning to leave the outer ring and is infalling for R <~ 8 kpc. H I is accumulating just beyond the inner ring, though optical (V - R) maps show gas and dust crossing the ring and flowing into the nucleus along two streams. No H I analogs of the optical "spokes" are found. The ring's surface brightness in Hα ({SIGMA}_Hα_) and 20 cm continuum ({SIGMA}_20 cm_) are identical, showing that peculiar extinction is not responsible for the observed crescent of MSF. Only the two most luminous H II complexes are detected at 6 cm and are characterized by nonthermal spectra (α^bar^ = - 0.65) and low 6 cm- Hα extinction (A^bar^_V_ = 1.7 mag). The 20 cm continuum-derived Type II SN rate (0.1 +/- 0.02 yr^-1^) is consistent with the lower bound of optical estimates. H I and Hα are both concentrated and anticorrelated in the outer ring. MSF appears to take place on the H I ring's leading edge throughout the starburst quadrant, where a disturbed H I component is found. The Cartwheel's gas consumption time-scale is 290 Myr. If the inner ring triggers a second sustained starburst, a significant fraction of the remaining gas supply may be converted into stars. The global distribution of MSF can be understood in terms of a critical surface density ({SIGMA}_crit_; reported by Kennicutt in 1989): Only in the outer ring does the atomic gas surface density ({SIGMA}_ag_) exceed {SIGMA}_crit_ when averaged over a full range in azimuth. At smaller radii

  14. Atmospheric CO2 source and sink patterns over the Indian region

    NASA Astrophysics Data System (ADS)

    Fadnavis, Suvarna; Kumar, K. Ravi; Tiwari, Yogesh K.; Pozzoli, Luca

    2016-02-01

    In this paper we examine CO2 emission hot spots and sink regions over India as identified from global model simulations during the period 2000-2009. CO2 emission hot spots overlap with locations of densely clustered thermal power plants, coal mines and other industrial and urban centres; CO2 sink regions coincide with the locations of dense forest. Fossil fuel CO2 emissions are compared with two bottom-up inventories: the Regional Emission inventories in ASia (REAS v1.11; 2000-2009) and the Emission Database for Global Atmospheric Research (EDGAR v4.2) (2000-2009). Estimated fossil fuel emissions over the hot spot region are ˜ 500-950 gC m-2 yr-1 as obtained from the global model simulation, EDGAR v4.2 and REAS v1.11 emission inventory. Simulated total fluxes show increasing trends, from 1.39 ± 1.01 % yr-1 (19.8 ± 1.9 TgC yr-1) to 6.7 ± 0.54 % yr-1 (97 ± 12 TgC yr-1) over the hot spot regions and decreasing trends of -0.95 ± 1.51 % yr-1 (-1 ± 2 TgC yr-1) to -5.7 ± 2.89 % yr-1 (-2.3 ± 2 TgC yr-1) over the sink regions. Model-simulated terrestrial ecosystem fluxes show decreasing trends (increasing CO2 uptake) over the sink regions. Decreasing trends in terrestrial ecosystem fluxes imply that forest cover is increasing, which is consistent with India State of Forest Report (2009). Fossil fuel emissions show statistically significant increasing trends in all the data sets considered in this study. Estimated trend in simulated total fluxes over the Indian region is ˜ 4.72 ± 2.25 % yr-1 (25.6 TgC yr-1) which is slightly higher than global growth rate ˜ 3.1 % yr-1 during 2000-2010.

  15. Nitrous oxide fluxes from three forest types of the tropical mountain rainforests on Hainan Island, China

    NASA Astrophysics Data System (ADS)

    Bai, Zhenzhi; Yang, Gang; Chen, Huai; Zhu, Qiuan; Chen, Dexiang; Li, Yide; Wang, Xu; Wu, Zhongmin; Zhou, Guangyi; Peng, Changhui

    2014-08-01

    Tropical rainforest soil is an important source of atmospheric nitrous oxide (N2O). However, there is still considerable uncertainty about the spatial and temporal variability of N2O fluxes. To understand these fluxes, we quantified the annual N2O emissions from three tropical mountain rainforests (primary mountain rainforest, PMR; secondary mountain rainforest, SMR; and Podocarpus imbricatus plantation, PIP) in the Jianfengling National Natural Reserve on Hainan Island, China. The average of N2O emissions in this area was 2.52 ± 0.33 kg N-N2O ha-1 yr-1 (3.52 kg N-N2O ha-1 yr-1 in the wet season and 1.62 kg N-N2O ha-1 yr-1 in the dry season) during our study period, with highly seasonal variations. The mean N2O emission rates were significantly higher during the wet season (68% of the total average) than the dry season (32% of the total average) (P < 0.05). PIP had the highest N2O emission rate at 3.49 ± 0.61 kg N-N2O ha-1 yr-1 (4.74 kg N-N2O ha-1 yr-1 in the wet season and 2.32 kg N-N2O ha-1 yr-1 in the dry season), followed by SMR at 3.03 ± 0.64 kg N-N2O ha-1 yr-1 (4.16 kg N-N2O ha-1 yr-1 in the wet season and 1.97 kg N-N2O ha-1 yr-1 in the dry season), and then PMR at 1.53 ± 0.49 kg N-N2O ha-1 yr-1 (2.21 kg N-N2O ha-1 yr-1 in the wet season and 0.94 kg N-N2O ha-1 yr-1 in the dry season). We observed a significant Gaussian relationship between the N2O fluxes and soil temperature for SMR and PIP but no significant relationship in PMR. There was a significant exponential relationship between the N2O fluxes and water filled pore space (WFPS) in SMR and PIP but not in PMR.

  16. First combined flux chamber survey of mercury and CO2 emissions from soil diffuse degassing at Solfatara of Pozzuoli crater, Campi Flegrei (Italy): Mapping and quantification of gas release

    NASA Astrophysics Data System (ADS)

    Bagnato, E.; Barra, M.; Cardellini, C.; Chiodini, G.; Parello, F.; Sprovieri, M.

    2014-12-01

    There have been limited studies to date targeting gaseous elemental mercury (GEM) flux from soil emission in enriched volcanic substrates and its relation with CO2 release and tectonic structures. In order to evaluate and understand the processes of soil-air exchanges involved at Solfatara of Pozzuoli volcano, the most active zone of Campi Flegrei caldera (Italy), an intensive field measurement survey has been achieved in September 2013 by using high-time resolution techniques. Soil-air exchange fluxes of GEM and CO2 have been measured simultaneously at 116 points, widely distributed within the crater. Quantification of gas flux has been assessed by using field accumulation chamber method in conjunction with a Lumex®-RA 915 + portable mercury vapor analyzer and a LICOR for CO2 determination, respectively. The spatial distribution of GEM and CO2 emissions correlated quite closely with the hydrothermal and geological features of the studied area. The highest GEM fluxes (from 4.04 to 5.9 × 10- 5 g m- 2 d- 1) were encountered close to the southern part of the crater interested by an intense fumarolic activity and along the SE-SW tectonic fracture (1.26 × 10- 6-6.91 × 10- 5 g GEM m- 2 d- 1). Conversely, the lowest values have been detected all along the western rim of the crater, characterized by a weak gas flux and a lush vegetation on a very sealed clay soil, which likely inhibited mercury emission (range: 1.5 × 10- 7-7.18 × 10- 6 g GEM m- 2 d- 1). Results indicate that the GEM exchange between soil and air inside the Solfatara crater is about 2-3 orders of magnitude stronger than that in the background areas (10- 8-10- 7 g m- 2 d- 1). CO2 soil diffuse degassing exhibited an analogous spatial pattern to the GEM fluxes, with emission rates ranging from about 15 to ~ 20,000 g CO2 m- 2 d- 1, from the outermost western zones to the south-eastern sector of the crater. The observed significant correlation between GEM and CO2 suggested that in volcanic system GEM

  17. Offshore influence of coastal upwelling off Mauritania, NW Africa, as recorded by diatoms in sediment traps at 2195 m water depth

    NASA Astrophysics Data System (ADS)

    Lange, Carina B.; Romero, Oscar E.; Wefer, Gerold; Gabric, Albert J.

    1998-06-01

    Downward flux and taxonomic composition of diatom and silicoflagellate assemblages were determined from sediment trap samples off Cap Blanc (CB1, NW Africa) over a 1-year period (March 1988-March 1989) and compared to the assemblages in the underlying surface sedi ment. Trap content was composed of biogenic and lithogenic material. The dominant constituents of the biogenic fraction were calcium carbonate, biogenic opal, and organic matter. Coccolithophorids, planktonic foraminifera and pteropods contributed to the CaCO 3 flux; opal derived mainly from diatoms. During the sampling year prominent total flux maxima occurred in spring and summer. Highest diatom flux values were reached in March-April (20.1×10 5 valves m -2 d -1) and July-August (22.9×10 5 valves m -2 d -1) in coincidence with the total flux pattern. Radiolaria showed three distinct peaks: in autumn (16×10 4 shells m -2 d -1), spring (˜11×10 4 shells m -2 d -1) and summer (10×10 4 shells m -2 d -1). The flux pattern of silicoflagellates differed greatly from those of the other groups and from the total particle flux, with highest values between October 1988 and March 1989. For all microorganisms surveyed, September was the month of lowest production. We identified a total of 166 diatom taxa and 3 silicoflagellate species. Off Cap Blanc, upwelling occurs year-round, and "giant filaments" of relatively high pigment concentration develop and persist throughout the year with substantial seasonal and interannual variations. We show that the shifts in siliceous phytoplankton do reflect both the seaward displacement of the coastal upwelling center and the periods of relaxation when oligotrophic waters prevail. Accumulation rates in the surface sediment were calculated to be 1.36×10 8 valves m -2 yr -1 for diatoms and 1.05×10 6 skeletons m -2 yr -1 for silicoflagellates. Most of the diatoms found in the water column at 2195 m also occurred in the sediment surface, with a slight enrichement of robust

  18. A detailed view of the gas shell around R Sculptoris with ALMA

    NASA Astrophysics Data System (ADS)

    Maercker, M.; Vlemmings, W. H. T.; Brunner, M.; De Beck, E.; Humphreys, E. M.; Kerschbaum, F.; Lindqvist, M.; Olofsson, H.; Ramstedt, S.

    2016-02-01

    Context. During the asymptotic giant branch (AGB) phase, stars undergo thermal pulses - short-lived phases of explosive helium burning in a shell around the stellar core. Thermal pulses lead to the formation and mixing-up of new elements to the stellar surface. They are hence fundamental to the chemical evolution of the star and its circumstellar envelope. A further consequence of thermal pulses is the formation of detached shells of gas and dust around the star, several of which have been observed around carbon-rich AGB stars. Aims: We aim to determine the physical properties of the detached gas shell around R Sculptoris, in particular the shell mass and temperature, and to constrain the evolution of the mass-loss rate during and after a thermal pulse. Methods: We analyse 12CO(1-0), 12CO(2-1), and 12CO(3-2) emission, observed with the Atacama Large Millimeter/submillimeter Array (ALMA) during Cycle 0 and complemented by single-dish observations. The spatial resolution of the ALMA data allows us to separate the detached shell emission from the extended emission inside the shell. We perform radiative transfer modelling of both components to determine the shell properties and the post-pulse mass-loss properties. Results: The ALMA data show a gas shell with a radius of 19.̋5 expanding at 14.3 km s-1. The different scales probed by the ALMA Cycle 0 array show that the shell must be entirely filled with gas, contrary to the idea of a detached shell. The comparison to single-dish spectra and radiative transfer modelling confirms this. We derive a shell mass of 4.5 × 10-3 M⊙ with a temperature of 50 K. Typical timescales for thermal pulses imply a pulse mass-loss rate of 2.3 × 10-5 M⊙ yr-1. For the post-pulse mass-loss rate, we find evidence for a gradual decline of the mass-loss rate, with an average value of 1.6 × 10-5 M⊙ yr-1. The total amount of mass lost since the last thermal pulse is 0.03 M⊙, a factor four higher compared to classical models, with a

  19. On the Nature of the Prototype Luminous Blue Variable Ag Carinae. I. Fundamental Parameters During Visual Minimum Phases and Changes in the Bolometric Luminosity During the S-Dor Cycle

    NASA Astrophysics Data System (ADS)

    Groh, J. H.; Hillier, D. J.; Damineli, A.; Whitelock, P. A.; Marang, F.; Rossi, C.

    2009-06-01

    We present a detailed spectroscopic analysis of the luminous blue variable (LBV) AG Carinae (AG Car) during the last two visual minimum phases of its S-Dor cycle (1985-1990 and 2000-2003). The analysis reveals an overabundance of He, N, and Na, and a depletion of H, C, and O, on the surface of the AG Car, indicating the presence of a CNO-processed material. Furthermore, the ratio N/O is higher on the stellar surface than in the nebula. We found that the minimum phases of AG Car are not equal to each other, since we derived a noticeable difference between the maximum effective temperature achieved during 1985-1990 (22, 800 K) and 2000-2001 (17,000 K). Significant differences between the wind parameters in these two epochs were also noticed. While the wind terminal velocity was 300 km s-1 in 1985-1990, it was as low as 105 km s-1 in 2001. The mass-loss rate, however, was lower from 1985-1990 (1.5 × 10-5 M sun yr-1) than from 2000-2001 (3.7 × 10-5 M sun yr-1). We found that the wind of AG Car is significantly clumped (f sime 0.10-0.25) and that clumps must be formed deep in the wind. We derived a bolometric luminosity of 1.5 × 106 L sun during both minimum phases which, contrary to the common assumption, decreases to 1.0 × 106 L sun as the star moves toward the maximum flux in the V band. Assuming that the decrease in the bolometric luminosity of AG Car is due to the energy used to expand the outer layers of the star, we found that the expanding layers contain roughly 0.6-2 M sun. Such an amount of mass is an order of magnitude lower than the nebular mass around AG Car, but is comparable to the nebular mass found around lower-luminosity LBVs and to that of the Little Homunculus of Eta Car. If such a large amount of mass is indeed involved in the S Dor-type variability, we speculate that such instability could be a failed Giant Eruption, with several solar masses never becoming unbound from the star. Based on observations made with the 1.6 m telescope at the

  20. A New Model for the Radio Emission from SN 1994I and an Associated Search for Radio Transients in M51

    NASA Astrophysics Data System (ADS)

    Alexander, Kate D.; Soderberg, Alicia M.; Chomiuk, Laura B.

    2015-06-01

    We revisit the exquisite archival radio data for the Type Ic supernova SN 1994I and present a revised model for the supernova (SN) radio emission and a pilot study that aims to constrain the rate of C-band radio transients within the face-on host galaxy, M51 (NGC 5194). We find that the temporal and spectral evolution of the SN 1994I radio emission are well fit by a synchrotron self-absorption model and use this to estimate physical parameters. We compute a pre-explosion mass loss rate of \\dot{M}=3.0× {{10}-5} {{M}⊙ } yr-1 for the progenitor, consistent with those observed from galactic Wolf-Rayet stars. Our model makes different assumptions for the dynamical model for the shockwave interaction than the model previously published by Weiler et al., but our \\dot{M} is consistent with theirs to within errors and assumptions. Drawing from a subset of the archival radio observations from the Very Large Array collected for the monitoring of SN 1994I, we conduct a pilot study to search for previously unidentified transients. Data were primarily taken at a frequency of 4.9 GHz and are logarithmic in cadence, enabling sensitivity to transients with variability timescales ranging from days to months. We find no new transient detections in 31 epochs of data, allowing us to place a 2σ upper limit of 17 deg-2 for the source density of radio transients above 0.5 mJy (L ≳ 4× {{10}25} erg s-1 Hz-1 at the distance of M51). This study highlights the feasibility of utilizing archival high-cadence radio studies of SN host galaxies to place constraints on the radio transient rate as a function of luminosity in the local universe.

  1. OISTER optical and near-infrared observations of the super-Chandrasekhar supernova candidate SN 2012dn: Dust emission from the circumstellar shell

    NASA Astrophysics Data System (ADS)

    Yamanaka, Masayuki; Maeda, Keiichi; Tanaka, Masaomi; Tominaga, Nozomu; Kawabata, Koji S.; Takaki, Katsutoshi; Kawabata, Miho; Nakaoka, Tatsuya; Ueno, Issei; Akitaya, Hiroshi; Nagayama, Takahiro; Takahashi, Jun; Honda, Satoshi; Omodaka, Toshihiro; Miyanoshita, Ryo; Nagao, Takashi; Watanabe, Makoto; Isogai, Mizuki; Arai, Akira; Itoh, Ryosuke; Ui, Takahiro; Uemura, Makoto; Yoshida, Michitoshi; Hanayama, Hidekazu; Kuroda, Daisuke; Ukita, Nobuharu; Yanagisawa, Kenshi; Izumiura, Hideyuki; Saito, Yoshihiko; Masumoto, Kazunari; Ono, Rikako; Noguchi, Ryo; Matsumoto, Katsura; Nogami, Daisaku; Morokuma, Tomoki; Oasa, Yumiko; Sekiguchi, Kazuhiro

    2016-05-01

    We present extensively dense observations of the super-Chandrasekhar supernova (SC SN) candidate SN 2012dn from -11 to +140 d after the date of its B-band maximum in the optical and near-infrared (NIR) wavelengths conducted through the OISTER ToO (Optical and Infrared Synergetic Telescopes for Education and Research Target of Opportunity) program. The NIR light curves and color evolutions up to 35 days after the B-band maximum provided an excellent match with those of another SC SN 2009dc, providing further support to the nature of SN 2012dn as an SC SN. We found that SN 2012dn exhibited strong excesses in the NIR wavelengths from 30 d after the B-band maximum. The H- and Ks-band light curves exhibited much later maximum dates at 40 and 70 d after the B-band maximum, respectively, compared with those of normal SNe Ia. The H- and Ks-band light curves subtracted by those of SN 2009dc displayed plateaued evolutions, indicating an NIR echo from the surrounding dust. The distance to the inner boundary of the dust shell is limited to 4.8-6.4 × 10-2 pc. No emission lines were found in its early phase spectra, suggesting that the ejecta-circumstellar material interaction could not occur. On the other hand, we found no signature that strongly supports the scenario of dust formation. The mass-loss rate of the pre-explosion system is estimated to be 10-6-10-5 M⊙ yr-1, assuming that the wind velocity of the system is 10-100 km s-1, which suggests that the progenitor of SN 2012dn could be a recurrent nova system. We conclude that the progenitor of this SC SN could be explained by the single-degenerate scenario.

  2. Massive stars on the verge of exploding: the properties of oxygen sequence Wolf-Rayet stars

    NASA Astrophysics Data System (ADS)

    Tramper, F.; Straal, S. M.; Sanyal, D.; Sana, H.; de Koter, A.; Gräfener, G.; Langer, N.; Vink, J. S.; de Mink, S. E.; Kaper, L.

    2015-09-01

    Context. Oxygen sequence Wolf-Rayet (WO) stars are a very rare stage in the evolution of massive stars. Their spectra show strong emission lines of helium-burning products, in particular highly ionized carbon and oxygen. The properties of WO stars can be used to provide unique constraints on the (post-)helium burning evolution of massive stars, and their remaining lifetimes and the expected properties of their supernovae. Aims: We aim to homogeneously analyze the currently known presumed-single WO stars to obtain the key stellar and outflow properties and to constrain their evolutionary state. Methods: We use the line-blanketed non-local thermal equilibrium atmosphere code cmfgen to model the X-Shooter spectra of the WO stars and to deduce the atmospheric parameters. We calculate dedicated evolutionary models to determine the evolutionary state of the stars. Results: The WO stars have extremely high temperatures that range from 150 kK to 210 kK, and very low surface helium mass fractions that range from 44% down to 14%. Their properties can be reproduced by evolutionary models with helium zero-age main sequence masses of MHe,ini = 15-25 M⊙ that exhibit a fairly strong (a few times 10-5M⊙ yr-1), homogeneous (fc> 0.3) stellar wind. Conclusions: WO stars represent the final evolutionary stage of stars with estimated initial masses of Mini = 40-60 M⊙. They are post core-helium burning and predicted to explode as type Ic supernovae within a few thousand years. Based on observations obtained at the European Southern Observatory under program IDs 091.C-0934 and 093.D-0591.Appendices are available in electronic form at http://www.aanda.org

  3. Shock Breakout and Early Light Curves of Type II-P Supernovae Observed with Kepler

    NASA Astrophysics Data System (ADS)

    Garnavich, Peter M.; Tucker, Bradley E.; Rest, Armin; Shaya, Edward J.; Olling, Robert; Kasen, Daniel; Villar, Victoria; KEGS

    2016-01-01

    We discovered two transient events in the Kepler field with light curves that strongly suggest they are type II-P supernovae. Using the fast cadence of the Kepler observations we precisely estimate the rise time to maximum for KSN2011a and KSN2011d as 10.5±0.4 and 13.3±0.4 rest-frame days respectively. We find the progenitor radius of KSN2011a (280±20 R⊙) to be significantly smaller than that for KSN2011d (490±20 R⊙) but both have similar explosion energies of 2.0±0.3 ×1051 erg.The rising light curve of KSN2011d is an excellent match to that predicted by simple models of exploding red supergiants (RSG). However, the early rise of KSN2011a is faster than the models predict possibly due to the supernova shockwave moving into pre-existing wind or mass-loss from the RSG. A mass loss rate of 10-4 M⊙ yr-1 from the RSG can explain the fast rise without impacting the optical flux at maximum light or the shape of the post-maximum light curve.No shock breakout emission is seen in KSN2011a, but this is likely due to the circumstellar interaction suspected in the fast rising light curve. The early light curve of KSN2011d does show excess emission consistent with model predictions of a shock breakout. This is the first optical detection of a shock breakout from a type II-P supernova.

  4. Methane bubbling from northern lakes: present and future contributions to the global methane budget.

    PubMed

    Walter, Katey M; Smith, Laurence C; Chapin, F Stuart

    2007-07-15

    Large uncertainties in the budget of atmospheric methane (CH4) limit the accuracy of climate change projections. Here we describe and quantify an important source of CH4 -- point-source ebullition (bubbling) from northern lakes -- that has not been incorporated in previous regional or global methane budgets. Employing a method recently introduced to measure ebullition more accurately by taking into account its spatial patchiness in lakes, we estimate point-source ebullition for 16 lakes in Alaska and Siberia that represent several common northern lake types: glacial, alluvial floodplain, peatland and thermokarst (thaw) lakes. Extrapolation of measured fluxes from these 16 sites to all lakes north of 45 degrees N using circumpolar databases of lake and permafrost distributions suggests that northern lakes are a globally significant source of atmospheric CH4, emitting approximately 24.2+/-10.5Tg CH4yr(-1). Thermokarst lakes have particularly high emissions because they release CH4 produced from organic matter previously sequestered in permafrost. A carbon mass balance calculation of CH4 release from thermokarst lakes on the Siberian yedoma ice complex suggests that these lakes alone would emit as much as approximately 49000Tg CH4 if this ice complex was to thaw completely. Using a space-for-time substitution based on the current lake distributions in permafrost-dominated and permafrost-free terrains, we estimate that lake emissions would be reduced by approximately 12% in a more probable transitional permafrost scenario and by approximately 53% in a 'permafrost-free' Northern Hemisphere. Long-term decline in CH4 ebullition from lakes due to lake area loss and permafrost thaw would occur only after the large release of CH4 associated thermokarst lake development in the zone of continuous permafrost. PMID:17513268

  5. Gross Nitrogen Mineralization in Surface Sediments of the Yangtze Estuary.

    PubMed

    Lin, Xianbiao; Hou, Lijun; Liu, Min; Li, Xiaofei; Yin, Guoyu; Zheng, Yanling; Deng, Fengyu

    2016-01-01

    Nitrogen mineralization is a key biogeochemical process transforming organic nitrogen to inorganic nitrogen in estuarine and coastal sediments. Although sedimentary nitrogen mineralization is an important internal driver for aquatic eutrophication, few studies have investigated sedimentary nitrogen mineralization in these environments. Sediment-slurry incubation experiments combined with 15N isotope dilution technique were conducted to quantify the potential rates of nitrogen mineralization in surface sediments of the Yangtze Estuary. The gross nitrogen mineralization (GNM) rates ranged from 0.02 to 5.13 mg N kg(-1) d(-1) in surface sediments of the study area. The GNM rates were generally higher in summer than in winter, and the relative high rates were detected mainly at sites near the north branch and frontal edge of this estuary. The spatial and temporal distributions of GNM rates were observed to depend largely on temperature, salinity, sedimentary organic carbon and nitrogen contents, and extracellular enzyme (urease and L-glutaminase) activities. The total mineralized nitrogen in the sediments of the Yangtze Estuary was estimated to be about 6.17 × 10(5) t N yr(-1), and approximately 37% of it was retained in the estuary. Assuming the retained mineralized nitrogen is totally released from the sediments into the water column, which contributed 12-15% of total dissolved inorganic nitrogen (DIN) sources in this study area. This result indicated that the mineralization process is a significant internal nitrogen source for the overlying water of the Yangtze Estuary, and thus may contribute to the estuarine and coastal eutrophication.

  6. A new dust budget in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Zhu, Chunhua; Lü, Guoliang; Wang, Zhaojun

    2015-08-01

    The origin of dust in a galaxy is poorly understood. Recently, surveys of the Large Magellanic Cloud (LMC) have provided astrophysical laboratories for dust studies. Using a method of population synthesis, we investigate the contributions of dust produced by asymptotic giant branch (AGB) stars, common envelope (CE) ejecta and Type II supernovae (SNe II) to the total dust budget in the LMC. Based on our models, the dust production rates (DPRs) of AGB stars in the LMC are between about 2.5 × 10-5 and 4.0 × 10-6 M⊙ yr-1. The uncertainty mainly results from different models for the dust yields of AGB stars. The DPRs of CE ejecta are about 6.3 × 10-6 (the initial binary fraction is 50 per cent). These results are within the large scatter of several observational estimates. AGB stars mainly produce carbon grains, which is consistent with observations. Most of the dust grains manufactured by CE ejecta are silicate and iron grains. The contributions of SNe II are very uncertain. Compared with SNe II without reverse shock, the DPRs of AGB stars and CE ejecta are negligible. However, if only 2 per cent of dust grains produced by SNe II can survive after reverse shock, the contributions of SNe II are very small. The total dust masses produced by AGB stars in the LMC are between 2.8 × 104 and 3.2 × 105 M⊙, and those produced by CE ejecta are about 6.3 × 104. They are much lower than the values estimated by observations. Therefore, there should be other dust sources in the LMC.

  7. Infall-driven Protostellar Accretion and the Solution to the Luminosity Problem

    NASA Astrophysics Data System (ADS)

    Padoan, Paolo; Haugbølle, Troels; Nordlund, Åke

    2014-12-01

    We investigate the role of mass infall in the formation and evolution of protostars. To avoid ad hoc initial and boundary conditions, we consider the infall resulting self-consistently from modeling the formation of stellar clusters in turbulent molecular clouds. We show that infall rates in turbulent clouds are comparable to accretion rates inferred from protostellar luminosities or measured in pre-main-sequence stars. They should not be neglected in modeling the luminosity of protostars and the evolution of disks, even after the embedded protostellar phase. We find large variations of infall rates from protostar to protostar, and large fluctuations during the evolution of individual protostars. In most cases, the infall rate is initially of order 10-5 M ⊙ yr-1, and may either decay rapidly in the formation of low-mass stars, or remain relatively large when more massive stars are formed. The simulation reproduces well the observed characteristic values and scatter of protostellar luminosities and matches the observed protostellar luminosity function. The luminosity problem is therefore solved once realistic protostellar infall histories are accounted for, with no need for extreme accretion episodes. These results are based on a simulation of randomly driven magnetohydrodynamic turbulence on a scale of 4 pc, including self-gravity, adaptive-mesh refinement to a resolution of 50 AU, and accreting sink particles. The simulation yields a low star formation rate, consistent with the observations, and a mass distribution of sink particles consistent with the observed stellar initial mass function during the whole duration of the simulation, forming nearly 1300 sink particles over 3.2 Myr.

  8. OISTER optical and near-infrared observations of the super-Chandrasekhar supernova candidate SN 2012dn: Dust emission from the circumstellar shell

    NASA Astrophysics Data System (ADS)

    Yamanaka, Masayuki; Maeda, Keiichi; Tanaka, Masaomi; Tominaga, Nozomu; Kawabata, Koji S.; Takaki, Katsutoshi; Kawabata, Miho; Nakaoka, Tatsuya; Ueno, Issei; Akitaya, Hiroshi; Nagayama, Takahiro; Takahashi, Jun; Honda, Satoshi; Omodaka, Toshihiro; Miyanoshita, Ryo; Nagao, Takashi; Watanabe, Makoto; Isogai, Mizuki; Arai, Akira; Itoh, Ryosuke; Ui, Takahiro; Uemura, Makoto; Yoshida, Michitoshi; Hanayama, Hidekazu; Kuroda, Daisuke; Ukita, Nobuharu; Yanagisawa, Kenshi; Izumiura, Hideyuki; Saito, Yoshihiko; Masumoto, Kazunari; Ono, Rikako; Noguchi, Ryo; Matsumoto, Katsura; Nogami, Daisaku; Morokuma, Tomoki; Oasa, Yumiko; Sekiguchi, Kazuhiro

    2016-10-01

    We present extensively dense observations of the super-Chandrasekhar supernova (SC SN) candidate SN 2012dn from -11 to +140 d after the date of its B-band maximum in the optical and near-infrared (NIR) wavelengths conducted through the OISTER ToO (Optical and Infrared Synergetic Telescopes for Education and Research Target of Opportunity) program. The NIR light curves and color evolutions up to 35 days after the B-band maximum provided an excellent match with those of another SC SN 2009dc, providing further support to the nature of SN 2012dn as an SC SN. We found that SN 2012dn exhibited strong excesses in the NIR wavelengths from 30 d after the B-band maximum. The H- and Ks-band light curves exhibited much later maximum dates at 40 and 70 d after the B-band maximum, respectively, compared with those of normal SNe Ia. The H- and Ks-band light curves subtracted by those of SN 2009dc displayed plateaued evolutions, indicating an NIR echo from the surrounding dust. The distance to the inner boundary of the dust shell is limited to 4.8-6.4 × 10-2 pc. No emission lines were found in its early phase spectra, suggesting that the ejecta-circumstellar material interaction could not occur. On the other hand, we found no signature that strongly supports the scenario of dust formation. The mass-loss rate of the pre-explosion system is estimated to be 10-6-10-5 M⊙ yr-1, assuming that the wind velocity of the system is 10-100 km s-1, which suggests that the progenitor of SN 2012dn could be a recurrent nova system. We conclude that the progenitor of this SC SN could be explained by the single-degenerate scenario.

  9. Regolith production and transport at the Susquehanna Shale Hills Critical Zone Observatory, Part 2: Insights from meteoric 10Be

    NASA Astrophysics Data System (ADS)

    West, Nicole; Kirby, Eric; Bierman, Paul; Slingerland, Rudy; Ma, Lin; Rood, Dylan; Brantley, Susan

    2013-09-01

    Regolith-mantled hillslopes are ubiquitous features of most temperate landscapes, and their morphology reflects the climatically, biologically, and tectonically mediated interplay between regolith production and downslope transport. Despite intensive research, few studies have quantified both of these mass fluxes in the same field site. Here we present an analysis of 87 meteoric 10Be measurements from regolith and bedrock within the Susquehanna Shale Hills Critical Zone Observatory (SSHO), in central Pennsylvania. Meteoric 10Be concentrations in bulk regolith samples (n = 73) decrease with regolith depth. Comparison of hillslope meteoric 10Be inventories with analyses of rock chip samples (n = 14) from a 24 m bedrock core confirms that >80% of the total inventory is retained in the regolith. The systematic downslope increase of meteoric 10Be inventories observed at SSHO is consistent with 10Be accumulation in slowly creeping regolith (~ 0.2 cm yr-1). Regolith flux inferred from meteoric 10Be varies linearly with topographic gradient (determined from high-resolution light detection and ranging-based topography) along the upper portions of hillslopes at SSHO. However, regolith flux appears to depend on the product of gradient and regolith depth where regolith is thick, near the base of hillslopes. Meteoric 10Be inventories at the north and south ridgetops indicate minimum regolith residence times of 10.5 ± 3.7 and 9.1 ± 2.9 ky, respectively, similar to residence times inferred from U-series isotopes in Ma et al. (2013). The combination of our results with U-series-derived regolith production rates implies that regolith production and erosion rates are similar to within a factor of two on SSHO hillcrests.

  10. Stellar Winds and Embedded Star Formation in the Galactic Center Quintuplet and Arches Clusters: Multifrequency Radio Observations

    NASA Astrophysics Data System (ADS)

    Lang, Cornelia C.; Johnson, Kelsey E.; Goss, W. M.; Rodríguez, Luis F.

    2005-11-01

    A multifrequency, multiconfiguration study has been made of the compact radio sources in the Galactic center Quintuplet and Arches stellar clusters using the Very Large Array. Ten radio sources have been detected in the Quintuplet cluster. The majority of these radio sources have rising spectral indices and are positionally coincident with young massive stars that are known to have powerful stellar winds. We conclude that the three most compact of these sources are produced by stellar wind emission; thus, mass-loss rates can be derived and have an average value of 3×10-5 Msolar yr-1. The remainder of the sources are likely to be a combination of stellar wind emission and free-free emission from surrounding ionized gas. In three cases, the radio sources have no stellar counterpart, and the radio emission is thought to arise from compact or ultracompact H II regions. If so, these sources would be the first detections of embedded massive stars to be discovered in the Galactic center clusters. The radio nebula associated with the Pistol star resembles the nebula surrounding the luminous blue variable star η Car and may be related to the stellar wind of the Pistol star. Ten compact radio sources are also detected in the Arches cluster and are interpreted to be stellar wind sources, consistent with previous findings. Several of the sources show moderate variability (10%-30%) in their flux density, possibly related to a nonthermal component in the wind emission. A number of radio sources in both clusters have X-ray counterparts, which have been interpreted to be the shocked, colliding winds of massive binary systems.

  11. Gross Nitrogen Mineralization in Surface Sediments of the Yangtze Estuary.

    PubMed

    Lin, Xianbiao; Hou, Lijun; Liu, Min; Li, Xiaofei; Yin, Guoyu; Zheng, Yanling; Deng, Fengyu

    2016-01-01

    Nitrogen mineralization is a key biogeochemical process transforming organic nitrogen to inorganic nitrogen in estuarine and coastal sediments. Although sedimentary nitrogen mineralization is an important internal driver for aquatic eutrophication, few studies have investigated sedimentary nitrogen mineralization in these environments. Sediment-slurry incubation experiments combined with 15N isotope dilution technique were conducted to quantify the potential rates of nitrogen mineralization in surface sediments of the Yangtze Estuary. The gross nitrogen mineralization (GNM) rates ranged from 0.02 to 5.13 mg N kg(-1) d(-1) in surface sediments of the study area. The GNM rates were generally higher in summer than in winter, and the relative high rates were detected mainly at sites near the north branch and frontal edge of this estuary. The spatial and temporal distributions of GNM rates were observed to depend largely on temperature, salinity, sedimentary organic carbon and nitrogen contents, and extracellular enzyme (urease and L-glutaminase) activities. The total mineralized nitrogen in the sediments of the Yangtze Estuary was estimated to be about 6.17 × 10(5) t N yr(-1), and approximately 37% of it was retained in the estuary. Assuming the retained mineralized nitrogen is totally released from the sediments into the water column, which contributed 12-15% of total dissolved inorganic nitrogen (DIN) sources in this study area. This result indicated that the mineralization process is a significant internal nitrogen source for the overlying water of the Yangtze Estuary, and thus may contribute to the estuarine and coastal eutrophication. PMID:26991904

  12. Fire-induced Carbon Emissions and Regrowth Uptake in Western U.S. Forests: Documenting Variation Across Forest Types, Fire Severity, and Climate Regions

    NASA Technical Reports Server (NTRS)

    Ghimire, Bardan; Williams, Christopher A.; Collatz, George James; Vanderhoof, Melanie

    2012-01-01

    The forest area in the western United States that burns annually is increasing with warmer temperatures, more frequent droughts, and higher fuel densities. Studies that examine fire effects for regional carbon balances have tended to either focus on individual fires as examples or adopt generalizations without considering how forest type, fire severity, and regional climate influence carbon legacies. This study provides a more detailed characterization of fire effects and quantifies the full carbon impacts in relation to direct emissions, slow release of fire-killed biomass, and net carbon uptake from forest regrowth. We find important variations in fire-induced mortality and combustion across carbon pools (leaf, live wood, dead wood, litter, and duff) and across low- to high-severity classes. This corresponds to fire-induced direct emissions from 1984 to 2008 averaging 4 TgC/yr and biomass killed averaging 10.5 TgC/yr, with average burn area of 2723 sq km/yr across the western United States. These direct emission and biomass killed rates were 1.4 and 3.7 times higher, respectively, for high-severity fires than those for low-severity fires. The results show that forest regrowth varies greatly by forest type and with severity and that these factors impose a sustained carbon uptake legacy. The western U.S. fires between 1984 and 2008 imposed a net source of 12.3 TgC/yr in 2008, accounting for both direct fire emissions (9.5 TgC/yr) and heterotrophic decomposition of fire-killed biomass (6.1 TgC yr1) as well as contemporary regrowth sinks (3.3 TgC/yr). A sizeable trend exists toward increasing emissions as a larger area burns annually.

  13. A Super-Eddington Wind Scenario for the Progenitors of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Ma, Xin; Chen, Xuefei; Chen, Hai-liang; Denissenkov, Pavel A.; Han, Zhanwen

    2013-12-01

    The accretion of hydrogen-rich material on to carbon-oxygen white dwarfs (CO WDs) is crucial for understanding Type Ia supernova (SN Ia) from the single-degenerate model, but this process has not been well understood due to the numerical difficulties in treating H and He flashes during the accretion. For CO WD masses from 0.5 to 1.378 M ⊙ and accretion rates in the range from 10-8 to 10-5 M ⊙ yr-1, we simulated the accretion of solar-composition material on to CO WDs using the state-of-the-art stellar evolution code of MESA. For comparison with steady-state models, we first ignored the contribution from nuclear burning to the luminosity when determining the Eddington accretion rate, and found that the properties of H burning in our accreting CO WD models are similar to those from the steady-state models, except that the critical accretion rates at which the WDs turn into red giants or H-shell flashes occur on their surfaces are slightly higher than those from the steady-state models. However, the super-Eddington wind is triggered at much lower accretion rates than previously thought, when the contribution of nuclear burning to the total luminosity is included. This super-Eddington wind naturally prevents the CO WDs with high accretion rates from becoming red giants, thus presenting an alternative to the optically thick wind proposed by Hachisu et al. Furthermore, the super-Eddington wind works in low-metallicity environments, which may explain SNe Ia observed at high redshifts.

  14. Super-Eddington wind scenario for the progenitors of type Ia supernovae: Accreting He-rich matter onto white dwarfs

    NASA Astrophysics Data System (ADS)

    Wang, B.; Li, Y.; Ma, X.; Liu, D.-D.; Cui, X.; Han, Z.

    2015-12-01

    Context. Supernovae of type Ia (SNe Ia) are believed to be thermonuclear explosions of carbon-oxygen white dwarfs (CO WDs). However, the mass accretion process onto CO WDs is still not completely understood. Aims: In this paper, we study the accretion of He-rich matter onto CO WDs and explore a scenario in which a strong wind forms on the surface of the WD if the total luminosity exceeds the Eddington limit. Methods: Using a stellar evolution code called modules for experiments in stellar astrophysics (MESA), we simulated the He accretion process onto CO WDs for WDs with masses of 0.6-1.35 M⊙ and various accretion rates of 10-8-10-5 M⊙ yr-1. Results: If the contribution of the total luminosity is included when determining the Eddington accretion rate, then a super-Eddington wind could be triggered at relatively lower accretion rates than those of previous studies based on steady-state models. The super-Eddington wind can prevent the WDs with high accretion rates from evolving into red-giant-like He stars. We found that the contributions from thermal energy of the WD are non-negligible, judging by our simulations, even though the nuclear burning energy is the dominating source of luminosity. We also provide the limits of the steady He-burning regime in which the WDs do not lose any accreted matter and increase their mass steadily, and calculated the mass retention efficiency during He layer flashes for various WD masses and accretion rates. These obtained results can be used in future binary population synthesis computations.

  15. Accreting pre-main-sequence models and abundance anomalies in globular clusters

    NASA Astrophysics Data System (ADS)

    Tognelli, E.; Prada Moroni, P. G.; Degl'Innocenti, S.

    2015-12-01

    We investigated the possibility of producing helium-enhanced stars in globular clusters by accreting polluted matter during the pre-main-sequence phase. We followed the evolution of two different classes of pre-main-sequence accreting models, one which neglects and the other that takes into account the protostellar evolution. We analysed the dependence of the final central helium abundance, of the tracks position in the HR diagram and of the surface lithium abundance evolution on the age at which the accretion of polluted material begins and on the main physical parameters that govern the protostellar evolution. The later is the beginning of the late accretion and the lower are both the central helium and the surface lithium abundances at the end of the accretion phase and in Zero Age Main Sequence (ZAMS). In order to produce a relevant increase of the central helium content the accretion of polluted matter should start at ages lower than 1 Myr. The inclusion of the protostellar evolution has a strong impact on the ZAMS models too. The adoption of a very low seed mass (i.e. 0.001 M⊙) results in models with the lowest central helium and surface lithium abundances. The higher is the accretion rate and the lower is the final helium content in the core and the residual surface lithium. In the worst case - i.e. seed mass 0.001 M⊙ and accretion rate ≥10-5 M⊙ yr-1 - the central helium is not increased at all and the surface lithium is fully depleted in the first few million years.

  16. The X-ray light curve of the massive colliding wind Wolf-Rayet + O binary WR 21a

    NASA Astrophysics Data System (ADS)

    Gosset, Eric; Nazé, Yaël

    2016-05-01

    Our dedicated XMM-Newton monitoring, as well as archival Chandra and Swift datasets, were used to examine the behaviour of the WN5h+O3V binary WR 21a at high energies. For most of the orbit, the X-ray emission exhibits few variations. However, an increase in strength of the emission is seen before periastron, following a 1 /D relative trend, where D is the separation between both components. This increase is rapidly followed by a decline due to strong absorption as the Wolf-Rayet (WR) comes in front. The fitted local absorption value appears to be coherent with a mass-loss rate of about 1 × 10-5 M⊙ yr-1 for the WR component. However, absorption is not the only parameter affecting the X-ray emission at periastron as even the hard X-ray emission decreases, suggesting a possible collapse of the colliding wind region near to or onto the photosphere of the companion just before or at periastron. An eclipse may appear as another potential scenario, but it would be in apparent contradiction with several lines of evidence, notably the width of the dip in the X-ray light curve and the absence of variations in the UV light curve. Afterwards, the emission slowly recovers, with a strong hysteresis effect. The observed behaviour is compatible with predictions from general wind-wind collision models although the absorption increase is too shallow. Based on observations collected at ESO as well as with Swift, Chandra, and the ESA science mission XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA).

  17. Star Formation in the Outer Disk of Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Barnes, Kate L.; van Zee, Liese; Côté, Stéphanie; Schade, David

    2012-09-01

    We combine new deep and wide field of view Hα imaging of a sample of eight nearby (d ≈ 17 Mpc) spiral galaxies with new and archival H I and CO imaging to study the star formation and the star formation regulation in the outer disk. We find that, in agreement with previous studies, star formation in the outer disk has low covering fractions, and star formation is typically organized into spiral arms. The star formation in the outer disk is at extremely low levels, with typical star formation rate surface densities of ~10-5 to 10-6 M ⊙ yr-1 kpc-2. We find that the ratio of the radial extent of detected H II regions to the radius of the H I disk is typically gsim85%. This implies that in order to further our understanding of the implications of extended star formation, we must further our understanding of the formation of extended H I disks. We measure the gravitational stability of the gas disk, and find that the outer gaseous disk is typically a factor of ~2 times more stable than the inner star-forming disk. We measure the surface density of outer disk H I arms, and find that the disk is closer to gravitational instability along these arms. Therefore, it seems that spiral arms are a necessary, but not sufficient, requirement for star formation in the outer disk. We use an estimation of the flaring of the outer gas disk to illustrate the effect of flaring on the Schmidt power-law index; we find that including flaring increases the agreement between the power-law indices of the inner and outer disks.

  18. Unbeamed tidal disruption events at hard X-rays

    NASA Astrophysics Data System (ADS)

    Hryniewicz, K.; Walter, R.

    2016-02-01

    Context. Owing to their thermal emission, tidal disruption events (TDEs) were regularly detected in the soft X-rays and sometimes in the optical. Only a few TDEs have been detected at hard X-rays: two are high redshift beamed events, one of which occurred at the core of a nearby galaxy, and the most recent one is of a different nature, involving a compact object in the Milky Way. Aims: The aims of this work are to obtain a first sample of hard X-ray-selected unbeamed TDEs, to determine their frequency and to probe whether TDEs usually or exceptionally emit at hard X-ray energies. Methods: We performed extensive searches for hard X-ray flares at positions in over 53 000 galaxies, up to a distance of 100 Mpc in the Swift/BAT archive. Light curves were extracted and parametrized. The quiescent hard X-ray emission was used to exclude persistently active galactic nuclei. Significant flares from non-active galaxies were derived and checked for possible contamination. Results: We found a sample of nine TDE candidates, which translates into a rate of 2 × 10-5 galaxy-1 yr-1 above the BAT detection limit. This rate is consistent with those observed by XMM-Newton at soft X-rays and in the optical from SDSS observations, and is as expected from simulations. We conclude that hard X-ray emission should be ubiquitous in un-beamed TDEs and that electrons should be accelerated in their accretion flow.

  19. Washout/rainout contribution in wet deposition estimated by 0.5 mm precipitation sampling/analysis

    NASA Astrophysics Data System (ADS)

    Aikawa, Masahide; Hiraki, Takatoshi

    A precipitation dataset collected on a 0.5 mm precipitation basis was studied. The parameters analyzed in this study were the pH (i.e., H + concentration), electric conductivity (EC), and SO42- and NO3- concentrations. The NO3- concentration clearly decayed with an increase of the precipitation amount, while a larger variation was observed in the SO42- concentration even when the precipitation amount increased. Assuming that the decaying NO3- concentration (0.70 μg ml -1) was the result of the rainout process, the estimates were: annual total deposition, 3252 mg m -2 yr -1; rainout process, 1092 mg m -2 yr -1; and rainout/total, 34%. The estimates for SO42- were: annual total deposition, 4687 mg m -2 yr -1; rainout process, 2096 mg m -2 yr -1; and rainout/total, 45%.

  20. Benthic macrofauna productivity enhancement by an artificial reef in Delaware Bay, USA

    SciTech Connect

    Steimle, F; Foster, Karen L.; Kropp, Roy K.; Conlin, B

    2002-10-15

    To understand the potential enhancement value of a habitat-loss mitigation reef in Delaware Bay, especially as a source of food for fishery resources, the secondary productivity of the reef epifauna and nearby sand infauna was estimated and compared. The mean production of natural sand infauna was estimated at between 215 and 249 kcal m(2) yr(-1), while that of the epifauna on the reef surfaces was between 3990 and 9555 kcal m(2) yr(-1). With the 36 m(2) footprint of a reef unit as a basis for comparison, the 407 m(2) of reef unit surface covering that footprint produced 1.62-3.89 X 10(6) kcal yr(-1) of epifauna compared with 7.74-8.96 X 10(3) kcal yr(-1) per footprint area for the adjacent sand infauna. There was, however, substantial annual variability in the productivity of the epifauna, based on the recruitment success of Mytilus edulis.

  1. Reviews and syntheses: Greenhouse gas emissions in natural and agricultural lands in sub-Saharan Africa: synthesis of available data and suggestions for further studies

    NASA Astrophysics Data System (ADS)

    Kim, D.-G.; Thomas, A. D.; Pelster, D.; Rosenstock, T. S.; Sanz-Cobena, A.

    2015-10-01

    This paper summarizes currently available data on greenhouse gas (GHG) emissions from African natural and agricultural lands, outlines the knowledge gaps and suggests future directions and strategies for GHG emission studies. GHG emission data were collected from 73 studies conducted in 22 countries in sub-Saharan Africa (SSA). Soil GHG emissions from African natural terrestrial systems ranged from 3.3 to 57.0 Mg carbon dioxide (CO2) ha-1 yr-1, -4.8 to 3.5 kg methane (CH4) ha-1 yr-1 and -0.1 to 13.7 kg nitrous oxide (N2O) ha-1 yr-1. Soil physical and chemical properties, rewetting, vegetation type, forest management and land-use changes were all found to be important factors affecting soil GHG emissions. Greenhouse gas emissions from African aquatic systems ranged from 5.7 to 232.0 Mg CO2 ha-1 yr-1, -26.3 to 2741.9 kg CH4 ha-1 yr-1 and 0.2 to 3.5 kg N2O ha-1 yr-1 and were strongly affected by discharge. Soil GHG emissions from African croplands ranged from 1.7 to 141.2 Mg CO2 ha-1 yr-1, -1.3 to 66.7 kg CH4 ha-1 yr-1and 0.05 to 112.0 kg N2O ha-1 yr-1 and the N2O emission factor (EF) ranged from 0.01 to 4.1 %. Incorporation of crop residues or manure with inorganic fertilizers resulted in significant changes in GHG emissions but these were different for CO2 and N2O. Soil GHG emissions in vegetable gardens ranged from 73.3 to 132.0 Mg CO2 ha-1 yr-1 and 53.4 to 177.6 kg N2O ha-1 yr-1 and N2O EFs ranged from 3 to 4 %. Soil CO2 and N2O emissions from agroforestry were 38.6 Mg CO2 ha-1 yr-1 and 0.2 to 26.7 kg N2O ha-1 yr-1, respectively. Improving fallow with nitrogen (N)-fixing trees increased CO2 and N2O emissions compared to conventional croplands and type and quality of plant residue is likely to be an important control factor affecting N2O emissions. Throughout agricultural lands, N2O emissions slowly increased with N inputs below 150 kg N ha-1 yr-1 and increased exponentially with N application rates up to 300 kg N ha-1 yr-1. The lowest yield-scaled N2O emissions

  2. Diapycnal diffusivity in the core and oxycline of the tropical North Atlantic oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Köllner, Manuela; Visbeck, Martin; Tanhua, Toste; Fischer, Tim

    2016-08-01

    Diapycnal diffusivity estimates from two Tracer Release Experiments (TREs) and microstructure measurements in the oxycline and core of the oxygen minimum zone (OMZ) in the Eastern Tropical North Atlantic (ETNA) are compared. For the first time, two TREs within the same area at different depths were realized: the Guinea Upwelling Tracer Release Experiment (GUTRE) initiated in 2008 in the oxycline at approximately 320 m depth, and the Oxygen Supply Tracer Release Experiment (OSTRE) initiated in 2012 in the core of the OMZ at approximately 410 m depth. The mean diapycnal diffusivity Dz was found to be insignificantly smaller in the OMZ core with (1.06 ± 0.24) × 10- 5 m2 s- 1 compared to (1.11 ± 0.22) × 10- 5 m2 s- 1 90 m shallower in the oxycline. Unexpectedly, GUTRE tracer was detected during two of the OSTRE surveys which showed that the estimated diapycnal diffusivity from GUTRE over a time period of seven years was within the uncertainty of the previous estimates over a time period of three years. The results are consistent with the Dz estimates from microstructure measurements and demonstrate that Dz does not vary significantly vertically in the OMZ within the depth range of 200-600 m and does not change with time. The presence of a seamount chain in the vicinity of the GUTRE injection region did not cause enhanced Dz compared to the smoother bottom topography of the OSTRE injection region, although the analysis of vertical shear spectra from ship ADCP data showed elevated internal wave energy level in the seamount vicinity. However, the two tracer patches covered increasingly overlapping areas with time and thus spatially integrated increasingly similar fields of local diffusivity, as well as the difference in local stratification counteracted the influence of roughness on Dz. For both experiments no significant vertical displacements of the tracer were observed, thus diapycnal upwelling within the ETNA OMZ is below the uncertainty level of 5 m yr- 1.

  3. Estimating Asian terrestrial carbon fluxes from CONTRAIL aircraft and surface CO2 observations for the period 2006 to 2010

    NASA Astrophysics Data System (ADS)

    Zhang, H. F.; Chen, B. Z.; van der Laan-Luijkx, I. T.; Machida, T.; Matsueda, H.; Sawa, Y.; Fukuyama, Y.; Labuschagne, C.; Langenfelds, R.; van der Schoot, M.; Xu, G.; Yan, J. W.; Zhou, L. X.; Tans, P. P.; Peters, W.

    2013-10-01

    Current estimates of the terrestrial carbon fluxes in Asia ("Asia" refers to lands as far west as the Urals and is divided into Boreal Eurasia, Temperate Eurasia and tropical Asia based on TransCom regions) show large uncertainties particularly in the boreal and mid-latitudes and in China. In this paper, we present an updated carbon flux estimate for Asia by introducing aircraft CO2 measurements from the CONTRAIL (Comprehensive Observation Network for Trace gases by Airline) program into an inversion modeling system based on the CarbonTracker framework. We estimated the averaged annual total Asian terrestrial land CO2 sink was about -1.56 Pg C yr-1 over the period 2006-2010, which offsets about one-third of the fossil fuel emission from Asia (+4.15 Pg C yr-1). The uncertainty of the terrestrial uptake estimate was derived from a set of sensitivity tests and ranged from -1.07 to -1.80 Pg C yr-1, comparable to the formal Gaussian error of ±1.18 Pg C yr-1 (1-sigma). The largest sink was found in forests, predominantly in coniferous forests (-0.64 Pg C yr-1) and mixed forests (-0.14 Pg C yr-1); and the second and third large carbon sinks were found in grass/shrub lands and crop lands, accounting for -0.44 Pg C yr-1 and -0.20 Pg C yr-1, respectively. The peak-to-peak amplitude of inter-annual variability (IAV) was 0.57 Pg C yr-1 ranging from -1.71 Pg C yr-1 to -2.28 Pg C yr-1. The IAV analysis reveals that the Asian CO2 sink was sensitive to climate variations, with the lowest uptake in 2010 concurrent with summer flood/autumn drought and the largest CO2 sink in 2009 owing to favorable temperature and plentiful precipitation conditions. We also found the inclusion of the CONTRAIL data in the inversion modeling system reduced the uncertainty by 11% over the whole Asian region, with a large reduction in the southeast of Boreal Eurasia, southeast of Temperate Eurasia and most Tropical Asian areas.

  4. Estimating Asian terrestrial carbon fluxes from CONTRAIL aircraft and surface CO2 observations for the period 2006-2010

    NASA Astrophysics Data System (ADS)

    Zhang, H. F.; Chen, B. Z.; Machida, T.; Matsueda, H.; Sawa, Y.; Fukuyama, Y.; Langenfelds, R.; van der Schoot, M.; Xu, G.; Yan, J. W.; Cheng, M. L.; Zhou, L. X.; Tans, P. P.; Peters, W.

    2014-06-01

    Current estimates of the terrestrial carbon fluxes in Asia show large uncertainties particularly in the boreal and mid-latitudes and in China. In this paper, we present an updated carbon flux estimate for Asia ("Asia" refers to lands as far west as the Urals and is divided into boreal Eurasia, temperate Eurasia and tropical Asia based on TransCom regions) by introducing aircraft CO2 measurements from the CONTRAIL (Comprehensive Observation Network for Trace gases by Airline) program into an inversion modeling system based on the CarbonTracker framework. We estimated the averaged annual total Asian terrestrial land CO2 sink was about -1.56 Pg C yr-1 over the period 2006-2010, which offsets about one-third of the fossil fuel emission from Asia (+4.15 Pg C yr-1). The uncertainty of the terrestrial uptake estimate was derived from a set of sensitivity tests and ranged from -1.07 to -1.80 Pg C yr-1, comparable to the formal Gaussian error of ±1.18 Pg C yr-1 (1-sigma). The largest sink was found in forests, predominantly in coniferous forests (-0.64 ± 0.70 Pg C yr-1) and mixed forests (-0.14 ± 0.27 Pg C yr-1); and the second and third large carbon sinks were found in grass/shrub lands and croplands, accounting for -0.44 ± 0.48 Pg C yr-1 and -0.20 ± 0.48 Pg C yr-1, respectively. The carbon fluxes per ecosystem type have large a priori Gaussian uncertainties, and the reduction of uncertainty based on assimilation of sparse observations over Asia is modest (8.7-25.5%) for most individual ecosystems. The ecosystem flux adjustments follow the detailed a priori spatial patterns by design, which further increases the reliance on the a priori biosphere exchange model. The peak-to-peak amplitude of inter-annual variability (IAV) was 0.57 Pg C yr-1 ranging from -1.71 Pg C yr-1 to -2.28 Pg C yr-1. The IAV analysis reveals that the Asian CO2 sink was sensitive to climate variations, with the lowest uptake in 2010 concurrent with a summer flood and autumn drought and the largest

  5. Assessing the integrated sediment trapping role of man-made and natural sediment sinks, Minizr catchment, Ethiopia

    NASA Astrophysics Data System (ADS)

    Mekonnen, Mulatie; Keesstra, Saskia; Stroosnijder, Leo; Baartman, Jantiene

    2016-04-01

    To enhance sedimentation within a catchment, man-made sediment trapping (ST) measures and natural sediment sinks are playing a vital role. To evaluate the ST role of such measures, this study was conducted at Minizr catchment, northwest Ethiopian highlands. Man-made soil and water conservation (SWC) structures constructed within the catchment and natural sediment sinks (floodplain and wetland) were digitized and quantified from Google earth imagery. Sediment pins, vertical cut measurements through the deposit (after the rainy season) and SWC structures dimension measurements (before and after the rainy seasons) were used to estimate the trapped sediment depth. Inflow and outflow suspended sediment measurements were done to calculate sediment trapping efficacies (STEs). On average, SWC structures trapped ~7922 t yr-1 (56 kg m-1 yr-1) and micro-trenches trapped ~13260 kg yr-1 (a micro-trench trapped 23 kg yr-1). A floodplain located near the centre of the catchment trapped ~ 9971 t yr-1 (59 kg m-2 yr-1) and a wetland located near the outlet of the catchment trapped ~ 8715 t yr-1 (36 kg m-2 yr-1). The STEs of the wetland and the floodplain were found to be 85 % and 77 %, respectively. Substantial difference was observed between the STE of grassed and un-grassed waterways, 75 % and 21 %, respectively. About ~40 % of the transported sediment was trapped by major sediment traps (both man-made and natural) and ~60 % is still leaving the catchment and entering into Koga reservoir. Although man-made structures and natural sediment sinks trapped large amount of sediment, the rate of sediment red-deposition is lower than the rate of sediment export at the outlet of the catchment, which is because of lack of an integrated ST approach.

  6. Atmospheric deposition of N, P and Fe to the Northern Indian Ocean: implications to C- and N-fixation.

    PubMed

    Srinivas, Bikkina; Sarin, M M

    2013-07-01

    This study presents the first data set on atmospheric input of N, P and Fe to the Northern Indian Ocean. Based on the chemical analysis of ambient aerosols, collected from the marine atmospheric boundary layer (MABL) during the continental outflow (January-April), we document that dry-deposition fluxes (μmolm(-2) d(-1)) of N (2-167), P (0.5-4.8) and Fe (0.02-1.2) to the Bay of Bengal are significantly higher compared to those over the Arabian Sea [N: 0.2-18.6; P: 0.3-0.9; Fe: 0.001-0.015]. Using atmospherically derived P and Fe, C-fixation (1.1 Pg yr(-1)) in the Bay of Bengal is dominated by anthropogenic sources. In contrast, C-fixation (0.03 Pg yr(-1)) in the Arabian Sea is limited by P and Fe. This is attributed to the poor fractional solubility of atmospheric mineral dust transported to the Arabian Sea. However, N-fixation by diazotrophs in the two oceanic regions is somewhat similar (0.5 Tg yr(-1)). Our estimate of N-deposition (0.2 Tg yr(-1)) to the Northern Indian Ocean is significantly lower compared to model results (~800-1200 mg-Nm(-2)yr(-1)≈5.7-8.6 Tg yr(-1) by Duce et al. (2008); ~4.1 Tg yr(-1) by Okin et al. (2011); ~0.8 Tg yr(-1) by Kanakidou et al. (2012)). An overestimate of N-deposition by models could arise due to inappropriate parameterization of temporal variability associated with the continental outflow spread over only four months. PMID:23584188

  7. Global trends and uncertainties in terrestrial denitrification and N₂O emissions.

    PubMed

    Bouwman, A F; Beusen, A H W; Griffioen, J; Van Groenigen, J W; Hefting, M M; Oenema, O; Van Puijenbroek, P J T M; Seitzinger, S; Slomp, C P; Stehfest, E

    2013-07-01

    Soil nitrogen (N) budgets are used in a global, distributed flow-path model with 0.5° × 0.5° resolution, representing denitrification and N2O emissions from soils, groundwater and riparian zones for the period 1900-2000 and scenarios for the period 2000-2050 based on the Millennium Ecosystem Assessment. Total agricultural and natural N inputs from N fertilizers, animal manure, biological N2 fixation and atmospheric N deposition increased from 155 to 345 Tg N yr(-1) (Tg = teragram; 1 Tg = 10(12) g) between 1900 and 2000. Depending on the scenario, inputs are estimated to further increase to 408-510 Tg N yr(-1) by 2050. In the period 1900-2000, the soil N budget surplus (inputs minus withdrawal by plants) increased from 118 to 202 Tg yr(-1), and this may remain stable or further increase to 275 Tg yr(-1) by 2050, depending on the scenario. N2 production from denitrification increased from 52 to 96 Tg yr(-1) between 1900 and 2000, and N2O-N emissions from 10 to 12 Tg N yr(-1). The scenarios foresee a further increase to 142 Tg N2-N and 16 Tg N2O-N yr(-1) by 2050. Our results indicate that riparian buffer zones are an important source of N2O contributing an estimated 0.9 Tg N2O-N yr(-1) in 2000. Soils are key sites for denitrification and are much more important than groundwater and riparian zones in controlling the N flow to rivers and the oceans. PMID:23713114

  8. Calculation of Manure Production and Excretion of Nitrogen, Phosphorous and Potassium by Dairy Cattle in the Comarca Lagunera

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study is to show how to calculate dairy manure production and the manure content of N, P and K. At the regional level, 7.5 x 106 ton yr-1 of fresh manure is produced, with 12.3% of dry matter (DM) content, for a total of 925,000 ton yr-1 (DM). Total N excreted is 46,200 ton yr-...

  9. Estimation of spatial apportionment of greenhouse gas emissions for the UK using boundary layer measurements and inverse modelling technique

    NASA Astrophysics Data System (ADS)

    Polson, D.; Fowler, D.; Nemitz, E.; Skiba, U.; McDonald, A.; Famulari, D.; Di Marco, C.; Simmons, I.; Weston, K.; Purvis, R.; Coe, H.; Manning, A. J.; Webster, H.; Harrison, M.; O'Sullivan, D.; Reeves, C.; Oram, D.

    2011-02-01

    A technique is described to independently validate the national emission inventories produced using the methodology of the Intergovernmental Panel on Climate Change (IPCC). A boundary layer budget approach is applied to the United Kingdom and an inverse modelling technique is used to derive total and spatial apportionment of emissions for CO, CO 2, CH 4, N 2O, HFC-134a, HCFC-141b, HCFC-142b and HCFC-22. During the summer of 2005 and September 2006 an aircraft circumnavigating the UK was used to collect data upwind and downwind of the UK coast. The concentration measurements were inverted to produce mapped emissions of the UK. The modelled overall CO flux (2900 ± 107 kt yr -1) and spatial apportionment throughout the UK are remarkably consistent with the official UK NAEI (National Atmospheric Emission Inventory) inventory. The CO 2 total emissions (620 ± 105 Mt yr -1) and spatial apportionment are also close to the NAEI. However for N 2O and CH 4, the estimated annual fluxes, 500 ± 370 kt yr -1 and 3500 (range 0-8000 kt yr -1) respectively, are larger than the NAEI albeit with significant uncertainty. Emissions of four halocarbon compounds were also calculated with total emissions of 3.1 ± 0.4 kt yr -1 for HFC-134a, 0.9 ± 0.6 kt yr -1 for HCFC-141b, 0.56 ± 0.2 kt yr -1 for HCFC-142b and 3.8 ± 1.0 kt yr -1 for HCFC-22 consistent with other published data.

  10. Reconciling estimates of the contemporary North American carbon balance among terrestrial biosphere models, atmospheric inversions, and a new approach for estimating net ecosystem exchange from inventory-based data

    USGS Publications Warehouse

    Hayes, Daniel J.; Turner, David P.; Stinson, Graham; McGuire, A. David; Wei, Yaxing; West, Tristram O.; Heath, Linda S.; de Jong, Bernardus; McConkey, Brian G.; Birdsey, Richard A.; Kurz, Werner A.; Jacobson, Andrew R.; Huntzinger, Deborah N.; Pan, Yude; Post, W. Mac; Cook, Robert B.

    2012-01-01

    We develop an approach for estimating net ecosystem exchange (NEE) using inventory-based information over North America (NA) for a recent 7-year period (ca. 2000–2006). The approach notably retains information on the spatial distribution of NEE, or the vertical exchange between land and atmosphere of all non-fossil fuel sources and sinks of CO2, while accounting for lateral transfers of forest and crop products as well as their eventual emissions. The total NEE estimate of a -327 ± 252 TgC yr-1 sink for NA was driven primarily by CO2 uptake in the Forest Lands sector (-248 TgC yr-1), largely in the Northwest and Southeast regions of the US, and in the Crop Lands sector (-297 TgC yr-1), predominantly in the Midwest US states. These sinks are counteracted by the carbon source estimated for the Other Lands sector (+218 TgC yr-1), where much of the forest and crop products are assumed to be returned to the atmosphere (through livestock and human consumption). The ecosystems of Mexico are estimated to be a small net source (+18 TgC yr-1) due to land use change between 1993 and 2002. We compare these inventory-based estimates with results from a suite of terrestrial biosphere and atmospheric inversion models, where the mean continental-scale NEE estimate for each ensemble is -511 TgC yr-1 and -931 TgC yr-1, respectively. In the modeling approaches, all sectors, including Other Lands, were generally estimated to be a carbon sink, driven in part by assumed CO2 fertilization and/or lack of consideration of carbon sources from disturbances and product emissions. Additional fluxes not measured by the inventories, although highly uncertain, could add an additional -239 TgC yr-1 to the inventory-based NA sink estimate, thus suggesting some convergence with the modeling approaches.

  11. Reconciling estimates of the contemporary North American carbon balance among terrestrial biosphere models, atmospheric inversions and a new approach for estimating net ecosystem exchange from inventory-based data

    SciTech Connect

    Hayes, Daniel J; Turner, David P; Stinson, Graham; Mcguire, David; Wei, Yaxing; West, Tristram O.; Heath, Linda S.; De Jong, Bernardus; McConkey, Brian G.; Birdsey, Richard A.; Kurz, Werner; Jacobson, Andrew; Huntzinger, Deborah; Pan, Yude; Post, Wilfred M; Cook, Robert B

    2012-01-01

    We develop an approach for estimating net ecosystem exchange (NEE) using inventory-based information over North America (NA) for a recent 7-year period (ca. 2000 2006). The approach notably retains information on the spatial distribution of NEE, or the vertical exchange between land and atmosphere of all non-fossil fuel sources and sinks of CO2, while accounting for lateral transfers of forest and crop products as well as their eventual emissions. The total NEE estimate of a 327 252 TgC yr1 sink for NA was driven primarily by CO2 uptake in the Forest Lands sector (248 TgC yr1), largely in the Northwest and Southeast regions of the US, and in the Crop Lands sector (297 TgC yr1), predominantly in the Midwest US states. These sinks are counteracted by the carbon source estimated for the Other Lands sector (+218 TgC yr1), where much of the forest and crop products are assumed to be returned to the atmosphere (through livestock and human consumption). The ecosystems of Mexico are estimated tobe a small net source (+18 TgC yr1) due to land use change between 1993 and 2002. We compare these inventorybased estimates with results from a suite of terrestrial biosphere and atmospheric inversion models, where the mean continental-scale NEE estimate for each ensemble is 511 TgC yr1 and 931 TgC yr1, respectively. In the modeling approaches, all sectors, including Other Lands, were generally estimated to be a carbon sink, driven in part by assumed CO2 fertilization and/or lack of consideration of carbon sources from disturbances and product emissions. Additional fluxes not measured by the inventories, although highly uncertain, could add an additional 239 TgC yr1 to the inventory-based NA sink estimate, thus suggesting some convergence with the modeling approaches.

  12. Atmospheric flux, transport and mass balance of (210)Pb and (137)Cs radiotracers in different regions of Romania.

    PubMed

    Begy, R Cs; Kovacs, T; Veres, D; Simon, H

    2016-05-01

    This study focuses on the determination of (210)Pb and (137)Cs fluxes from different areas in Transylvania, Romania and on the determination of transport and mass balance within the lacustrine system of Red Lake. In order to achieve this, samples were taken from six different locations (Bihor County area, Ighiel area, Red Lake area, Mluha Peatbog, Mohos Peatbog and Zanoaga Rosie Peat bog in the Semenic Mountains) throughout Romania, these being compared to the values of the Danube Delta area. The activity concentrations of the soil samples were measured by gamma spectrometry (HPGe detector) for both (210)Pbtotal, (210)Pbsup ((226)Ra) and (137)Cs, while peat samples were measured by both alpha ((210)Po) spectrometry (PIPS detectors) as well. The mean value for the (210)Pb flux was measured in the Danube Delta region (42±8Bqm(-2) yr(-1)), while the highest was measured in the Semenic Peatbog (227±54Bqm(-2) yr(-1)); the average being 132±8Bqm(-2) yr(-1). In case of (137)Cs the mean was 298±3Bqm(-2) yr(-1), maximum being 1683±15Bqm(-2) yr(-1) in case of Ighiel area and minimum being 32±1Bqm(-2) yr(-1) in the Danube Delta region. In case of the Red Lake, from the total inventory of 410±23Bqm(-2) yr(-1) in the sediments, the loss by outflows is 100±12Bqm(-2) yr(-1), the catchment to lake transfer factor being 0.84%. PMID:26922393

  13. Revisiting the Earth's sea-level and energy budgets from 1961 to 2008

    USGS Publications Warehouse

    Church, John A.; White, Neil J.; Konikow, Leonard F.; Domingues, Catia M.; Cogley, J. Graham; Rignot, Eric; Gregory, Jonathan M.; van den Broeke, Michiel R.; Monaghan, Andrew J.; Velicogna, Isabella

    2011-01-01

    We review the sea-level and energy budgets together from 1961, using recent and updated estimates of all terms. From 1972 to 2008, the observed sea-level rise (1.8 0.2 mm yr-1 from tide gauges alone and 2.1 0.2 mm yr -1 from a combination of tide gauges and altimeter observations) agrees well with the sum of contributions (1.8 0.4 mm yr-1) in magnitude and with both having similar increases in the rate of rise during the period. The largest contributions come from ocean thermal expansion (0.8 mm yr-1) and the melting of glaciers and ice caps (0.7 mm yr -1), with Greenland and Antarctica contributing about 0.4 mm yr -1. The cryospheric contributions increase through the period (particularly in the 1990s) but the thermosteric contribution increases less rapidly. We include an improved estimate of aquifer depletion (0.3 mm yr -1), partially offsetting the retention of water in dams and giving a total terrestrial storage contribution of-0.1 mm yr-1. Ocean warming (90% of the total of the Earth's energy increase) continues through to the end of the record, in agreement with continued greenhouse gas forcing. The aerosol forcing, inferred as a residual in the atmospheric energy balance, is estimated as-0.8 0.4 W m-2 for the 1980s and early 1990s. It increases in the late 1990s, as is required for consistency with little surface warming over the last decade. This increase is likely at least partially related to substantial increases in aerosol emissions from developing nations and moderate volcanic activity. Copyright 2011 by the American Geophysical Union.

  14. Global trends and uncertainties in terrestrial denitrification and N₂O emissions.

    PubMed

    Bouwman, A F; Beusen, A H W; Griffioen, J; Van Groenigen, J W; Hefting, M M; Oenema, O; Van Puijenbroek, P J T M; Seitzinger, S; Slomp, C P; Stehfest, E

    2013-07-01

    Soil nitrogen (N) budgets are used in a global, distributed flow-path model with 0.5° × 0.5° resolution, representing denitrification and N2O emissions from soils, groundwater and riparian zones for the period 1900-2000 and scenarios for the period 2000-2050 based on the Millennium Ecosystem Assessment. Total agricultural and natural N inputs from N fertilizers, animal manure, biological N2 fixation and atmospheric N deposition increased from 155 to 345 Tg N yr(-1) (Tg = teragram; 1 Tg = 10(12) g) between 1900 and 2000. Depending on the scenario, inputs are estimated to further increase to 408-510 Tg N yr(-1) by 2050. In the period 1900-2000, the soil N budget surplus (inputs minus withdrawal by plants) increased from 118 to 202 Tg yr(-1), and this may remain stable or further increase to 275 Tg yr(-1) by 2050, depending on the scenario. N2 production from denitrification increased from 52 to 96 Tg yr(-1) between 1900 and 2000, and N2O-N emissions from 10 to 12 Tg N yr(-1). The scenarios foresee a further increase to 142 Tg N2-N and 16 Tg N2O-N yr(-1) by 2050. Our results indicate that riparian buffer zones are an important source of N2O contributing an estimated 0.9 Tg N2O-N yr(-1) in 2000. Soils are key sites for denitrification and are much more important than groundwater and riparian zones in controlling the N flow to rivers and the oceans.

  15. Simulated melt rates for the Totten and Dalton ice shelves

    NASA Astrophysics Data System (ADS)

    Gwyther, D. E.; Galton-Fenzi, B. K.; Hunter, J. R.; Roberts, J. L.

    2014-05-01

    The Totten Glacier is rapidly losing mass. It has been suggested that this mass loss is driven by changes in oceanic forcing; however, the details of the ice-ocean interaction are unknown. Here we present results from an ice shelf-ocean model of the region that includes the Totten, Dalton and Moscow University ice shelves, based on the Regional Oceanic Modeling System for the period 1992-2007. Simulated area-averaged basal melt rates (net basal mass loss) for the Totten and Dalton ice shelves are 9.1 m ice yr-1 (44.5 Gt ice yr-1) and 10.1 m ice yr-1 (46.6 Gt ice yr-1), respectively. The melting of the ice shelves varies strongly on seasonal and interannual timescales. Basal melting (mass loss) from the Totten ice shelf spans a range of 5.7 m ice yr-1 (28 Gt ice yr-1) on interannual timescales and 3.4 m ice yr-1 (17 Gt ice yr-1) on seasonal timescales. This study links basal melt of the Totten and Dalton ice shelves to warm water intrusions across the continental shelf break and atmosphere-ocean heat exchange. Totten ice shelf melting is high when the nearby Dalton polynya interannual strength is below average, and vice versa. Melting of the Dalton ice shelf is primarily controlled by the strength of warm water intrusions across the Dalton rise and into the ice shelf cavity. During periods of strong westward coastal current flow, Dalton melt water flows directly under the Totten ice shelf further reducing melting. This is the first such modelling study of this region to provide a valuable framework for directing future observational and modelling efforts.

  16. Ice flow and mass continuity of Shumsky Glacier in the Djungarski Alatau Range of Kazakhstan, Central Asia

    NASA Astrophysics Data System (ADS)

    Cherkasov, Piotr A.; Ahmetova, Galia S.; Hastenrath, Stefan

    1996-05-01

    The glaciological monitoring program on the Shumsky Glacier in the Djungarski Alatau Range of southeastern Kazakhstan has included measurements of horizontal surface ice flow velocity, net balance, and emergence velocity at a network of more than 200 stakes during 1967-1991, as well as mappings of the ice surface topography by double-theodolite triangulation and determination of ice thickness and of bedrock topography by radio echo sounding in 1984. These observations are here evaluated together to deduce the long-term average dynamic behavior of Shumsky Glacier. The glacier extends between 3100 and 4400 m with a total area of 3 km2 and length of nearly 4 km. Maximum surface velocity is 20 m yr-1 and maximum volume flux 9 × 105 m3 yr-1, located near the equilibrium line altitude around 3680 m. The ice-volume-equivalent net balance is +0.5 m yr-1 in the average over the accumulation area, changing to about -1.5 m yr-1 near the terminus. The submergent flow in the accumulation area changes to emergence of 1 m yr-1 in the lower glacier. The rate of ice thinning is less than 0.1 m yr-1 in the middle glacier, increases to 2.5 m yr-1 near the terminus, and averages 0.12 m yr-1 for the glacier as whole. In fact, the Shumsky glacier differs little from equilibrium, being in a more favorable location that the other glaciers of the Djungarski Alatau. However, trends toward slower ice flow, more negative net balance, and faster rate of ice thinning indicate response to a progressively adverse climatic environment.

  17. Surface N balances and reactive N loss to the environment from global intensive agricultural production systems for the period 1970-2030.

    PubMed

    Bouwman, A F; Van Drecht, G; van der Hoek, K W

    2005-12-01

    Abstract Data for the historical years 1970 and 1995 and the FAO-Agriculture Towards 2030 projection are used to calculate N inputs (N fertilizer, animal manure, biological N fixation and atmospheric deposition) and the N export from the field in harvested crops and grass and grass consumption by grazing animals. In most industrialized countries we see a gradual increase of the overall N recovery of the intensive agricultural production systems over the whole 1970-2030 period. In contrast, low N input systems in many developing countries sustained low crop yields for many years but at the cost of soil fertility by depleting soil nutrient pools. In most developing countries the N recovery will increase in the coming decades by increasing efficiencies of N use in both crop and livestock production systems. The surface balance surplus of N is lost from the agricultural system via different pathways, including NH3 volatilization, denitrification, N20 and NO emissions, and nitrate leaching from the root zone. Global NH3-N emissions from fertilizer and animal manure application and stored manure increased from 18 to 34 Tg x yr(-1) between 1970 and 1995, and will further increase to 44 Tg x yr(-1) in 2030. Similar developments are seen for N2O-N (2.0 Tg x yr(-1) in 1970, 2.7 Tg x yr(-1) in 1995 and 3.5 Tg x yr(-1) in 2030) and NO-N emissions (1.1 Tg x yr(-1) in 1970, 1.5 Tg x yr(-1) in 1995 and 2.0 Tg x yr(-1) in 2030).

  18. Atmospheric deposition of N, P and Fe to the Northern Indian Ocean: implications to C- and N-fixation.

    PubMed

    Srinivas, Bikkina; Sarin, M M

    2013-07-01

    This study presents the first data set on atmospheric input of N, P and Fe to the Northern Indian Ocean. Based on the chemical analysis of ambient aerosols, collected from the marine atmospheric boundary layer (MABL) during the continental outflow (January-April), we document that dry-deposition fluxes (μmolm(-2) d(-1)) of N (2-167), P (0.5-4.8) and Fe (0.02-1.2) to the Bay of Bengal are significantly higher compared to those over the Arabian Sea [N: 0.2-18.6; P: 0.3-0.9; Fe: 0.001-0.015]. Using atmospherically derived P and Fe, C-fixation (1.1 Pg yr(-1)) in the Bay of Bengal is dominated by anthropogenic sources. In contrast, C-fixation (0.03 Pg yr(-1)) in the Arabian Sea is limited by P and Fe. This is attributed to the poor fractional solubility of atmospheric mineral dust transported to the Arabian Sea. However, N-fixation by diazotrophs in the two oceanic regions is somewhat similar (0.5 Tg yr(-1)). Our estimate of N-deposition (0.2 Tg yr(-1)) to the Northern Indian Ocean is significantly lower compared to model results (~800-1200 mg-Nm(-2)yr(-1)≈5.7-8.6 Tg yr(-1) by Duce et al. (2008); ~4.1 Tg yr(-1) by Okin et al. (2011); ~0.8 Tg yr(-1) by Kanakidou et al. (2012)). An overestimate of N-deposition by models could arise due to inappropriate parameterization of temporal variability associated with the continental outflow spread over only four months.

  19. Global budget of ethane and regional constraints on U.S. sources

    NASA Astrophysics Data System (ADS)

    Xiao, Yaping; Logan, Jennifer A.; Jacob, Daniel J.; Hudman, Rynda C.; Yantosca, Robert; Blake, Donald R.

    2008-11-01

    We use a 3-D chemical transport model (the GEOS-Chem CTM) to evaluate a global emission inventory for ethane (C2H6), with a best estimate for the global source of 13 Tg yr-1, 8.0 Tg yr-1 from fossil fuel production, 2.6 Tg yr-1 from biofuel, and 2.4 Tg yr-1 from biomass burning. About 80% of the source is emitted in the Northern Hemisphere. The model generally provides a reasonable and unbiased simulation of surface air observations, column measurements, and aircraft profiles worldwide, including patterns of geographical and seasonal variability. The main bias is a 20%-30% overestimate at European surface sites. Propagation of the C2H6 seasonal signal from northern midlatitudes to the equatorial western Pacific and the southern tropics demonstrates the dominance of northern midlatitudes as a source of C2H6 worldwide. Interhemispheric transport provides the largest C2H6 source to the Southern Hemisphere (1.7 Tg yr-1), and southern biomass burning provides the other major source (1.0 Tg yr-1). The C2H6 emission inventory for the United States from the Environmental Protection Agency (0.6 Tg yr-1) is considerably lower than our estimate constrained by extensive aircraft observations in the continental boundary layer (2.4 Tg yr-1). This appears to reflect a factor 7 underestimate in the fossil fuel source over the south-central United States. Our estimate of C2H6 emissions, together with observed ratios of CH4:C2H6, suggests that CH4 emissions from energy production in the U.S. may be underestimated by as much as 50%-100%.

  20. H2O vapor excitation in dusty AGB envelopes. A PACS view of OH 127.8+0.0

    NASA Astrophysics Data System (ADS)

    Lombaert, R.; Decin, L.; de Koter, A.; Blommaert, J. A. D. L.; Royer, P.; De Beck, E.; de Vries, B. L.; Khouri, T.; Min, M.

    2013-06-01

    Context. AGB stars lose a large percentage of their mass in a dust-driven wind. This creates a circumstellar envelope, which can be studied through thermal dust emission and molecular emission lines. In the case of high mass-loss rates, this study is complicated by the high optical depths and the intricate coupling between gas and dust radiative transfer characteristics. An important aspect of the physics of gas-dust interactions is the strong influence of dust on the excitation of several molecules, including H2O. Aims: The dust and gas content of the envelope surrounding the high mass-loss rate OH/IR star OH 127.8+0.0, as traced by Herschel observations, is studied, with a focus on the H2O content and the dust-to-gas ratio. We report detecting a large number of H2O vapor emission lines up to J = 9 in the Herschel data, for which we present the measured line strengths. Methods: The treatments of both gas and dust species are combined using two numerical radiative transfer codes. The method is illustrated for both low and high mass-loss-rate sources. Specifically, we discuss different ways of assessing the dust-to-gas ratio: 1) from the dust thermal emission spectrum and the CO molecular gas line strengths; 2) from the momentum transfer from dust to gas and the measured gas terminal velocity; and 3) from the determination of the required amount of dust to reproduce H2O lines for a given H2O vapor abundance. These three diagnostics probe different zones of the outflow, for the first time allowing an investigation of a possible radial dependence of the dust-to-gas ratio. Results: We modeled the infrared continuum and the CO and H2O emission lines in OH 127.8+0.0 simultaneously. We find a dust-mass-loss rate of (0.5 ± 0.1) × 10-6 M⊙ yr-1 and an H2O ice fraction of 16% ± 2% with a crystalline-to-amorphous ratio of 0.8 ± 0.2. The gas temperature structure is modeled with a power law, leading to a constant gas-mass-loss rate between 2 × 10-5 M⊙ yr-1 and 1 × 10

  1. On the evolutionary status of the donors in the low mass X-ray binary systems containing black holes or neutron stars

    NASA Astrophysics Data System (ADS)

    Ziolkowski, Janusz

    2016-07-01

    We consider donors (optical components) in four low mass X-ray binaries: two black hole systems (GRS1915+105/V1387 Aql and GS 2023+338/V404 Cyg) and two neutron star systems (X2127+119 and IGR J17451-3022). In all four cases we found that donors are most likely so called "stripped" giants. Such star consists of a degenerate, nearly isothermal helium core and a more or less depleted hydrogen rich envelope. Both parts are separated by a hydrogen burning shell. The structure of such an object is relatively simple and easy to model. In all four systems we can estimate relatively precisely the radii of the donors (which depend almost exclusively on the orbital periods). In two black hole systems we can additionally estimate their luminosities. Analysing the internal structure of the donors, we found that they could be "stripped" giants in all four systems. The likely masses are ~ 0.28 Msun for V1387 Aql, ~ 0.54 Msun for V404 Cyg, ~ 0.16-0.17 Msun for the companion of X2127+119 and ~ 0.15-0.2 Msun for the companion of IGR J17451-3022. For the last system another possible solution is a MS star of ~ 0.75 Msun.

  2. Water for food and nature in drought-prone tropics: vapour shift in rain-fed agriculture.

    PubMed Central

    Rockström, Johan

    2003-01-01

    This paper quantifies the eco-hydrological challenge up until 2050 of producing food in balance with goods and services generated by water-dependent ecosystems in nature. Particular focus is given to the savannah zone, covering 40% of the land area in the world, where water scarcity constitutes a serious constraint to sustainable development. The analysis indicates an urgent need for a new green revolution, which focuses on upgrading rain-fed agriculture. Water requirements to produce adequate diets for humans are shown to be relatively generic irrespective of hydro-climate, amounting to a global average of 1,300 m(3) cap(-1) yr(-1). Present food production requires an estimated 6,800 km(3) yr(-1) of consumptive green water (5,000 km(3) yr(-1) in rain-fed agriculture and 1,800 km(3) yr(-1) from irrigated crops). Without considering water productivity gains, an additional 5,800 km(3) yr(-1) of water is needed to feed a growing population in 2,050 and eradicate malnutrition. It is shown that the bulk of this water will be used in rain-fed agriculture. A dynamic analysis of water productivity and management options indicates that large 'crop per drop' improvements can be achieved at the farm level. Vapour shift in favour of productive green water flow as crop transpiration could result in relative water savings of 500 km(3) yr(-1) in semi-arid rain-fed agriculture. PMID:14728794

  3. Relationship between C:N/C:O Stoichiometry and Ecosystem Services in Managed Production Systems

    PubMed Central

    Ghaley, Bhim B.; Sandhu, Harpinder S.; Porter, John R.

    2015-01-01

    Land use and management intensity can influence provision of ecosystem services (ES). We argue that forest/agroforestry production systems are characterized by relatively higher C:O/C:N and ES value compared to arable production systems. Field investigations on C:N/C:O and 15 ES were determined in three diverse production systems: wheat monoculture (Cwheat), a combined food and energy system (CFE) and a beech forest in Denmark. The C:N/C:O ratios were 194.1/1.68, 94.1/1.57 and 59.5/1.45 for beech forest, CFE and Cwheat, respectively. The economic value of the non-marketed ES was also highest in beech forest (US$ 1089 ha-1 yr-1) followed by CFE (US$ 800 ha-1 yr-1) and Cwheat (US$ 339 ha-1 yr-1). The combined economic value was highest in the CFE (US$ 3143 ha-1 yr-1) as compared to the Cwheat (US$ 2767 ha-1 yr-1) and beech forest (US$ 2365 ha-1 yr-1). We argue that C:N/C:O can be used as a proxy of ES, particularly for the non-marketed ES, such as regulating, supporting and cultural services. These ES play a vital role in the sustainable production of food and energy. Therefore, they should be considered in decision making and developing appropriate policy responses for land use management. PMID:25894553

  4. Comparison of land nitrogen budgets for European agriculture by various modeling approaches.

    PubMed

    de Vries, W; Leip, A; Reinds, G J; Kros, J; Lesschen, J P; Bouwman, A F

    2011-11-01

    A comparison of nitrogen (N) budgets for the year 2000 of agro-ecosystems is made for the EU 27 countries by four models with different complexity and data requirements, i.e. INTEGRATOR, IDEAg, MITERRA and IMAGE. The models estimate a comparable total N input in European agriculture, i.e. 23.3-25.7 Mton N yr(-1), but N uptake varies more, i.e. from 11.3 to 15.4 Mton N yr(-1) leading to total N surpluses varying from 10.4 to 13.2 Mton N yr(-1). The estimated overall variation at EU 27 is small for the emissions of ammonia (2.8-3.1 Mton N yr(-1)) and nitrous oxide (0.33-0.43 Mton N yr(-1)), but large for the sum of N leaching and runoff (2.7-6.3 Mton N yr(-1)). Unlike the overall EU estimates, the difference in N output fluxes between models is large at regional scale. This is mainly determined by N inputs, differences being highest in areas with high livestock density.

  5. The carbon balance of Russia

    NASA Astrophysics Data System (ADS)

    Dolman, Han; Shvidenko, Anatoly; Recapp Russia Synthesis Team

    2013-04-01

    We determine the net land to atmosphere flux of carbon in Russia, including Ukraine, Belarus and Kazakhstan using inventory based, eddy covariance, and inversion methods. Our high boundary estimate is -342 Tg C yr-1 from the eddy covariance method, and this is close to the upper bounds of the inventory based Land Ecosystem Assessment and inverse models estimate. A lower boundary estimate is provided at -1350 Tg C yr-1 from from the inversion models. The average of the three methods is -613.5 Tg C yr-1. The methane emission is estimated separately at 41.4 TgC yr-1. These three methods agree well within their respective error bounds. There is thus good consistency between bottom up and top down methods. The forests of Russia primarily cause the net atmosphere to land flux ( -692 Tg C yr-1 from the LEA) with remarkable little interannual variability. It remains however remarkable that the three methods provide such close estimates (-615, -662, -554 TgCyr-1) for NBP, given the inherent uncertainties in all of the approaches. The lack of recent forest inventories, the few eddy covariance sites and associated uncertainty with upscaling and under sampling of concentrations for the inversions are among the prime causes of the uncertainty. The DGVMs suggest a much lower uptake at -91Tg C yr-1 and we argue that this is caused by a high estimate of heterotrophic respiration compared to other methods.

  6. Gull contributions of phosphorus and nitrogen to a Cape Cod kettle pond

    USGS Publications Warehouse

    Portnoy, J.W.; Soukup, M.A.

    1990-01-01

    Nutrient excretion rates and the annual contribution of P from the feces of the gulls Larus argentatus and L. marinus (and of N from L. argentatus) to the nutrient budget of Gull Pond (Wellfleet), a soft water seepage lake, have been estimated. Intensive year-round gull counts by species were combined with determinations of defecation rate and the nutrient content of feces to quantitatively assess the P loading rates associated with regular gull use of this coastal pond on a seasonal and annual basis. Total P loading from gulls was estimated to be 52 kg yr?1, with 17 kg from L. argentatus and 35 kg from L. marinus, resulting from about 5.0 ? 106 h yr?1 and 1.7 ? 106 h yr?1 of pond use. This compares with P loading estimates of 67 kg yr?1 from upgradient septic systems, 2 kg yr?1 from precipitation and 3 kg yr?1 from unpolluted ground water. Fifty-six percent of annual gull P loading was associated with migratory activity in late fall. Estimated annual N loading by L. argentatus was 14 kg TKN, 206 g NO3-N, and 1.85 g g NH3-N.

  7. Nitrogen in crop production: An account of global flows

    NASA Astrophysics Data System (ADS)

    Smil, Vaclav

    1999-06-01

    Human activities have roughly doubled the amount of reactive N that enters the element's biospheric cycle. Crop production is by far the single largest cause of this anthropogenic alteration. Inorganic fertilizers now provide 80 Tg N yr-1 (Tg = 1012 g), managed (symbiotic) biofixation adds about 20 Tg N yr-1, and between 28 and 36 Tg N yr-1 are recycled in organic wastes. Anthropogenic inputs (including N in seeds and irrigation water) now supply about 85% of 170 (151-186) Tg N reaching the world's cropland every year. About half of this input, 85 Tg N yr-1, is taken up by harvested crops and their residues. Quantification of N losses from crop fields is beset by major uncertainties. Losses to the atmosphere (denitrification and volatilization) amount to 26-60 Tg N yr-1, while waters receive (from leaching and erosion) 32-45 Tg N yr-1. These N losses are the major reason behind the growing concerns about the enrichment of the biosphere with reactive N. The best evidence suggests that in spite of some significant local and regional losses, the world's agricultural land accumulates N. The addition of 3-4 billion people before the year 2050 will require further substantial increases of N input in cropping, but a large share of this demand can come from improved efficiency of N fertilizer use.

  8. Greenhouse gas emissions from natural ecosystems and agricultural lands in sub-Saharan Africa: synthesis of available data and suggestions for further research

    NASA Astrophysics Data System (ADS)

    Kim, Dong-Gill; Thomas, Andrew D.; Pelster, David; Rosenstock, Todd S.; Sanz-Cobena, Alberto

    2016-08-01

    This paper summarizes currently available data on greenhouse gas (GHG) emissions from African natural ecosystems and agricultural lands. The available data are used to synthesize current understanding of the drivers of change in GHG emissions, outline the knowledge gaps, and suggest future directions and strategies for GHG emission research. GHG emission data were collected from 75 studies conducted in 22 countries (n = 244) in sub-Saharan Africa (SSA). Carbon dioxide (CO2) emissions were by far the largest contributor to GHG emissions and global warming potential (GWP) in SSA natural terrestrial systems. CO2 emissions ranged from 3.3 to 57.0 Mg CO2 ha-1 yr-1, methane (CH4) emissions ranged from -4.8 to 3.5 kg ha-1 yr-1 (-0.16 to 0.12 Mg CO2 equivalent (eq.) ha-1 yr-1), and nitrous oxide (N2O) emissions ranged from -0.1 to 13.7 kg ha-1 yr-1 (-0.03 to 4.1 Mg CO2 eq. ha-1 yr-1). Soil physical and chemical properties, rewetting, vegetation type, forest management, and land-use changes were all found to be important factors affecting soil GHG emissions from natural terrestrial systems. In aquatic systems, CO2 was the largest contributor to total GHG emissions, ranging from 5.7 to 232.0 Mg CO2 ha-1 yr-1, followed by -26.3 to 2741.9 kg CH4 ha-1 yr-1 (-0.89 to 93.2 Mg CO2 eq. ha-1 yr-1) and 0.2 to 3.5 kg N2O ha-1 yr-1 (0.06 to 1.0 Mg CO2 eq. ha-1 yr-1). Rates of all GHG emissions from aquatic systems were affected by type, location, hydrological characteristics, and water quality. In croplands, soil GHG emissions were also dominated by CO2, ranging from 1.7 to 141.2 Mg CO2 ha-1 yr-1, with -1.3 to 66.7 kg CH4 ha-1 yr-1 (-0.04 to 2.3 Mg CO2 eq. ha-1 yr-1) and 0.05 to 112.0 kg N2O ha-1 yr-1 (0.015 to 33.4 Mg CO2 eq. ha-1 yr-1). N2O emission factors (EFs) ranged from 0.01 to 4.1 %. Incorporation of crop residues or manure with inorganic fertilizers invariably resulted in significant changes in GHG emissions, but results were inconsistent as the magnitude and direction of

  9. Global riverine N and P transport to ocean increased during the 20th century despite increased retention along the aquatic continuum

    NASA Astrophysics Data System (ADS)

    Beusen, Arthur H. W.; Bouwman, Alexander F.; Van Beek, Ludovicus P. H.; Mogollón, José M.; Middelburg, Jack J.

    2016-04-01

    Various human activities - including agriculture, water consumption, river damming, and aquaculture - have intensified over the last century. This has had a major impact on nitrogen (N) and phosphorus (P) cycling in global continental waters. In this study, we use a coupled nutrient-input-hydrology-in-stream nutrient retention model to quantitatively track the changes in the global freshwater N and P cycles over the 20th century. Our results suggest that, during this period, the global nutrient delivery to streams increased from 34 to 64 Tg N yr-1 and from 5 to 9 Tg P yr-1. Furthermore, in-stream retention and removal grew from 14 to 27 Tg N yr-1 and 3 to 5 Tg P yr-1. One of the major causes of increased retention is the growing number of reservoirs, which now account for 24 and 22 % of global N and P retention/removal in freshwater systems, respectively. This increase in nutrient retention could not balance the increase in nutrient delivery to rivers with the consequence that river nutrient transport to the ocean increased from 19 to 37 Tg N yr-1 and from 2 to 4 Tg P yr-1. Human activities have also led to a global increase in the molar N : P ratio in freshwater bodies.

  10. Global riverine N and P transport to ocean increased during the twentieth century despite increased retention along the aquatic continuum

    NASA Astrophysics Data System (ADS)

    Beusen, A. H. W.; Bouwman, A. F.; Van Beek, L. P. H.; Mogollón, J. M.; Middelburg, J. J.

    2015-12-01

    Various human activities, including agriculture, water consumption, river damming, and aquaculture, have intensified over the last century. This has had a major impact on nitrogen (N) and phosphorus (P) cycling in global continental waters. In this study, we use a coupled nutrient-input, hydrology, in-stream nutrient retention model to quantitatively track the changes in the global freshwater N and P cycles over the 20th century. Our results suggest that, during this period, the global nutrient delivery to streams increased from 34 to 64 Tg N yr-1 and from 5 to 9 Tg N yr-1. Furthermore, in-stream retention and removal grew from 14 to 27 Tg N yr-1 and 3 to 5 Tg N yr-1. One of the major cause of increased retention is the growing number of reservoirs which now account for 24 and 22 % of global N and P retention/removal in freshwater systems, respectively. This increase in nutrient retention could not balance the increase in nutrient delivery to rivers with the consequence that river nutrient transport to the ocean increased from 19 to 37 Tg N yr-1 and from 2 to 4 Tg N yr-1. Human activities have also led to a global increase in the molar N : P ratio in freshwater bodies.

  11. Fifteen-Year Global Time Series of Satellite-Derived Fine Particulate Matter

    SciTech Connect

    Boys, B. L.; Martin, R. V.; van Donkelaar, A.; MacDonell, R. J.; Hsu, N. C.; Cooper, M. J.; Yantosca, R. M.; Lu, Z.; Streets, D. G.; Zhang, Q.; Wang, S. W.

    2014-10-07

    Ambient fine particulate matter (PM2.5) is a leading environmental risk factor for premature mortality. We use aerosol optical depth (AOD) retrieved from two satellite instruments, MISR and SeaWiFS, to produce a unified 15-year global time series (1998-2012) of ground-level PM2.5 concentration at a resolution of 1 degrees x 1 degrees. The GEOS-Chem chemical transport model (CTM) is used to relate each individual AOD retrieval to ground-level PM2.5. Four broad areas showing significant, spatially coherent, annual trends are examined in detail: the Eastern U.S. (-0.39 +/- 0.10 mu g m(-3) yr(-1)), the Arabian Peninsula (0.81 +/- 0.21 mu g m(-3) yr(-1)), South Asia (0.93 +/- 0.22 mu g m(-3) yr(-1)) and East Asia (0.79 +/- 0.27 mu g m(-3) yr(-1)). Over the period of dense in situ observation (1999-2012), the linear tendency for the Eastern U.S. (-0.37 +/- 0.13 mu g m(-3) yr(-1)) agrees well with that from in situ measurements (-0.38 +/- 0.06 mu g m(-3) yr(-1)). A GEOS-Chem simulation reveals that secondary inorganic aerosols largely explain the observed PM2.5 trend over the Eastern U.S., South Asia, and East Asia, while mineral dust largely explains the observed trend over the Arabian Peninsula.

  12. Comprehensive multiyear carbon budget of a temperate headwater stream

    NASA Astrophysics Data System (ADS)

    Argerich, Alba; Haggerty, Roy; Johnson, Sherri L.; Wondzell, Steven M.; Dosch, Nicholas; Corson-Rikert, Hayley; Ashkenas, Linda R.; Pennington, Robert; Thomas, Christoph K.

    2016-05-01

    Headwater streams comprise nearly 90% of the total length of perennial channels in global catchments. They mineralize organic carbon entering from terrestrial systems, evade terrestrial carbon dioxide (CO2), and generate and remove carbon through in-stream primary production and respiration. Despite their importance, headwater streams are often neglected in global carbon budgets primarily because of a lack of available data. We measured these processes, in detail, over a 10 year period in a stream draining a 96 ha forested watershed in western Oregon, USA. This stream, which represents only 0.4% of the watershed area, exported 159 kg C ha-1 yr-1, similar to the global exports for large rivers. Stream export was dominated by downstream transport of dissolved inorganic carbon (63 kg C ha-1 yr-1) and by evasion of CO2 to the atmosphere (42 kg C ha-1 yr-1), leaving the remainder of 51 kg C ha-1 yr-1 for downstream transport of organic carbon (17 kg C ha-1 yr-1 and 34 kg C ha-1 yr-1 in dissolved and particulate form, respectively).

  13. Calibrating the Mass-Luminosity Relation at the End of the Main Sequence

    NASA Astrophysics Data System (ADS)

    Henry, Todd

    2000-07-01

    This is a continuation of GO 6047/6566/7493/8282. We use HST-FGS3/1R to calibrate the mass-luminosity relation {MLR} for stars less massive than 0.2 Msun, with special emphasis on objects near the stellar/brown dwarf border. Our goals are to determine Mv values to 0.10 magnitude, masses to 5%, and more than double the number of objects with masses determined to be less than 0.20 Msun. This program uses the combination of HST-FGS3/1R at optical wavelengths and ground-based infrared speckle work to examine nearby, subarcsecond binary systems. Several of the objects included have M < 0.1 Msun, placing them at the very end of the stellar main sequence, and making them brown dwarf candidates.

  14. Calibrating the Mass-Luminosity Relation at the End of the Main Sequence

    NASA Astrophysics Data System (ADS)

    Henry, Todd

    1999-07-01

    This is a continuation request for GO 6047/6566/7493. We will use HST-FGS1R to calibrate the mass-luminosity relation {MLR} for stars less massive than 0.2 Msun, with special emphasis on objects near the stellar/brown dwarf border. Our goals are to determine M_V values to 0.10 magnitude, masses to 5%, and more than double the number of objects with masses determined to be less than 0.20 Msun. This program uses the combination of HST-FGS3/FGS1R at optical wavelengths and ground-based infrared speckle work to examine nearby, subarcsecond binary systems. Several of the objects included have M < 0.1 Msun, placing them at the very end of the stellar main sequence, and making them brown dwarf candidates.

  15. A low pre-infall mass for the Carina dwarf galaxy from disequilibrium modelling

    PubMed Central

    Ural, Uğur; Wilkinson, Mark I.; Read, Justin I.; Walker, Matthew G.

    2015-01-01

    Dark matter-only simulations of galaxy formation predict many more subhalos around a Milky Way-like galaxy than the number of observed satellites. Proposed solutions require the satellites to inhabit dark matter halos with masses 109–1010 Msun at the time they fell into the Milky Way. Here we use a modelling approach, independent of cosmological simulations, to obtain a pre-infall mass of Msun for one of the Milky Way's satellites: Carina. This determination of a low halo mass for Carina can be accommodated within the standard model only if galaxy formation becomes stochastic in halos below ∼1010 Msun. Otherwise Carina, the eighth most luminous Milky Way dwarf, would be expected to inhabit a significantly more massive halo. The implication of this is that a population of ‘dark dwarfs' should orbit the Milky Way: halos devoid of stars and yet more massive than many of their visible counterparts. PMID:26133650

  16. Strain accumulation and rotation in western Nevada, 1993-2000

    USGS Publications Warehouse

    Svarc, J.L.; Savage, J.C.; Prescott, W.H.; Ramelli, A.R.

    2002-01-01

    The positions of 44 GPS monuments in an array extending from the Sierra Nevada at the latitude of Reno to near Austin, Nevada, have been measured several times in the 1993-2000 interval. The western half of the array spans the Walker Lane belt, whereas the eastern half spans the central Nevada seismic zone (CNSZ). The principal strain rates in the Walker Lane belt are 29.6 ?? 5.3 nstrain yr-1 N88.4??E ?? 5.4?? and -12.8 ?? 6.0 nanostrain yr-1 N01.6??W ?? 5.4??, extension reckoned positive, and the clockwise (as seen from above the Earth) rotation rate about a vertical axis is 13.6 ?? 4.0 nrad yr-1. The quoted uncertainties are standard deviations. The motion in the Walker Lane belt can then be represented by a zone striking N35??W subject to 16.8 ?? 4.9 nstrain yr-1 extension perpendicular to it and 19.5 ?? 4.0 nstrain yr-1 right-lateral, simple shear across it. The N35??W strike of the zone is the same as the direction of the local tangent to the small circle drawn about the Pacific-North America pole of rotation. The principal strain rates for the CNSZ are 46.2 ?? 11.0 nstrain yr-1 N49.9??W ?? 6.0?? and -13.6 ?? 6.1 nstrain yr-1 N40.1??E ?? 6.0??, and the clockwise rotation rate about a vertical axis is 20.3 ?? 6.3 nrad yr-1. The motion across the CNSZ can then be represented by a zone striking N12??E subject to 32.6 ?? 11.0 nstrain yr-1 extension perpendicular to it and 25.1 ?? 6.3 nstrain yr-1 right-lateral, simple shear across it. The N12??E strike of the zone is similar to the strikes of the faults (Rainbow Mountain, Fairview Peak, and Dixie Valley) within it.

  17. Recent decadal trends in global phytoplankton composition

    NASA Astrophysics Data System (ADS)

    Rousseaux, Cecile S.; Gregg, Watson W.

    2015-10-01

    Identifying major trends in biogeochemical composition of the oceans is essential to improve our understanding of biological responses to climate forcing. Using the NASA Ocean Biogeochemical Model combined with ocean color remote sensing data assimilation, we assessed the trends in phytoplankton composition (diatoms, cyanobacteria, coccolithophores, and chlorophytes) at a global scale for the period 1998-2012. We related these trends in phytoplankton to physical conditions (surface temperature, surface photosynthetically available radiation (PAR), and mixed layer depth (MLD)) and nutrients (iron, silicate, and nitrate). We found a significant global decline in diatoms (-1.22% yr-1, p < 0.05). This trend was associated with a significant (p < 0.05) shallowing of the MLD (-0.20% yr-1), a significant increase in PAR (0.09% yr-1), and a significant decline in nitrate (-0.38% yr-1). The global decline in diatoms was mostly attributed to their decline in the North Pacific (-1.00% yr-1, p < 0.05), where the MLD shallowed significantly and resulted in a decline in all three nutrients (p < 0.05). None of the other phytoplankton groups exhibited a significant change globally, but regionally there were considerable significant trends. A decline in nutrients in the northernmost latitudes coincided with a significant decline in diatoms (North Pacific, -1.00% yr-1) and chlorophytes (North Atlantic, -9.70% yr-1). In the northern midlatitudes (North Central Pacific and Atlantic) where nutrients were more scarce, a decline in nutrients was associated with a decline in smaller phytoplankton: cyanobacteria declined significantly in the North Central Pacific (-0.72% yr-1) and Atlantic (-1.56% yr-1), and coccolithophores declined significantly in the North Central Atlantic (-2.06% yr-1). These trends represent the diversity and complexity of mechanisms that drives phytoplankton communities to adapt to variable conditions of nutrients, light, and mixed layer depth. These results provide

  18. Population dynamics and secondary production of the cockle Cerastoderma edule: A comparison between Merja Zerga (Moroccan Atlantic Coast) and Arcachon Bay (French Atlantic Coast)

    NASA Astrophysics Data System (ADS)

    Gam, Mériame; de Montaudouin, Xavier; Bazairi, Hocein

    2010-04-01

    Cockle ( Cerastoderma edule) population dynamics were studied at the southern limit of the distribution of this marine bivalve in Merja Zerga, Morocco. Parameters such as growth, mortality, and production were compared with those of a population at Arcachon Bay (France) a site in the center of the cockle's range. At each sampling period between two and three cohorts were simultaneously observed at each site and the average total abundance was usually higher at Merja Zerga. Recruitment occurred at both sites in spring when temperature rose above 19 °C, independently of the month. In Merja Zerga, winter recruitment was also observed at one occasion, following high sediment disturbance. The first year (2005-06) at Merja Zerga, the mortality rate was close to nil for juveniles and was Z = 1.5 yr - 1 for adults, providing a high production (64 g dry weight m - 2 yr - 1 ). At Arcachon during the same period, the juvenile mortality rate was Z = 10.9 yr - 1 , the adult mortality rate was 3.4 yr - 1 and production was 26 gDW m -2 yr - 1 . The second year (2006-07), mortality after recruitment was much higher ( Z = 8.6 yr - 1 , for juveniles) and similar to what was observed at Arcachon ( Z = 8.4 yr - 1 ). Mortality rate of adults was higher at Merja Zerga ( Z = 3.0 yr - 1 ) than at Arcachon ( Z = 1.5 yr - 1 ). Production was lower at Arcachon than at Merja Zerga although growth performances were higher at Arcachon. The higher growth performance at Arcachon ( Φ' = 3.3) was mainly due to high asymptotic length ( L∞ = 38 mm) and was related to low intraspecific competition compared to Merja Zerga where cockle abundance was higher ( Φ' = 3.1, L∞ = 31 mm). P/B was low in both sites and slightly higher at Arcachon (1.1-1.5 against 1.0-1.1 yr - 1 ). At Arcachon, recruitment was correlated with temperature, a peak occurring when temperature rose above 19 °C (June-July). At Merja Zerga, recruitment was already 2-3 months earlier but was not significantly correlated to

  19. Environmental footprints show China and Europe’s evolving resource appropriation for soybean production in Mato Grosso, Brazil

    NASA Astrophysics Data System (ADS)

    Lathuillière, Michael J.; Johnson, Mark S.; Galford, Gillian L.; Couto, Eduardo G.

    2014-07-01

    Mato Grosso has become the center of Brazil’s soybean industry, with production located across an agricultural frontier expanding into savanna and rainforest biomes. We present environmental footprints of soybean production in Mato Grosso and resource flows accompanying exports to China and Europe for the 2000s using five indicators: deforestation, land footprint (LF), carbon footprint (CF), water footprint (WF), and nutrient footprints. Soybean production was associated with 65% of the state’s deforestation, and 14-17% of total Brazilian land use change carbon emissions. The decade showed two distinct production systems illustrated by resources used in the first and second half of the decade. Deforestation and carbon footprint declined 70% while land, water, and nutrient footprints increased almost 30% between the two periods. These differences coincided with a shift in Mato Grosso’s export destination. Between 2006 and 2010, China surpassed Europe in soybean imports when production was associated with 97 m2 deforestation yr-1 ton-1 of soybean, a LF of 0.34 ha yr-1 ton-1, a carbon footprint of 4.6 ton CO2-eq yr-1 ton-1, a WF of 1908 m3 yr-1 ton-1, and virtual phosphorous and potassium of 5.0 kg P yr-1 ton-1 and 0.0042 g K yr-1 ton-1. Mato Grosso constructs soil fertility via phosphorous and potassium fertilizer sourced from third party countries and imported into the region. Through the soybean produced, Mato Grosso then exports both water derived from its abundant, seasonal precipitation and nutrients obtained from fertilizer. In 2010, virtual water flows were 10.3 km3 yr-1 to China and 4.1 km3 yr-1 to Europe. The total embedded nutrient flows to China were 2.12 Mtons yr-1 and 2.85 Mtons yr-1 to Europe. As soybean production grows with global demand, the role of Mato Grosso’s resource use and production vulnerabilities highlight the challenges with meeting future international food security needs.

  20. Comparison of Forest Carbon Changes in China and the Continental U.S.

    NASA Astrophysics Data System (ADS)

    Ju, W.

    2015-12-01

    Weimin Ju1, Chunhua Zhang1, Jing M. Chen2, Fangmin Zhang3, Xiqun Wang4, 1International Institute for Earth System Science, Nanjing University, Nanjing, 210023, China 2 Department of Geography, University of Toronto, Toronto, Ontario, Canada 3Jiangsu Key Laboratory of Agricultural Meteorology, College of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing, Jiangsu, China 4Planning and Design Institute of Forest Products Industry, State Forestry Administration of China, Beijing, 100010, China Carbon changes of forests in China and the continental U.S. were investigated using national forest inventory datasets and the InTEC model, which integrates the effects of forest age, atmospheric CO2concentration, nitrogen deposition, and climate. Pervious to simulations, the changes of net primary productivity (NPP) in the InTEC model was calibrated using field measured NPP and ages of forests. Both forest inventory and model simulations indicated that carbon sequestration by forests in China increased significantly in recent decades. The forest inventory based estimates indicated that biomass carbon sinks of forest stands were 86.0 Tg C yr-1 and 174.0 Tg C yr-1 in China and 132.5 Tg C yr-1and 147.0 Tg C yr-1 in the continental U.S. during the periods from 1989 to 2008 and from 1999 to 2008, respectively. The InTEC model simulations indicated that the total carbon sinks of forests were 170.4 Tg C yr-1, 200.2 Tg C yr-1, 217.7 Tg C yr-1 in China and 225.9 Tg C yr-1, 222.7 Tg C yr-1, and 230.5 Tg C yr-1 in the continental U.S. during the periods from 1981 to 2010, from 1991 to 2010, and from 2001 to 2010, respectively. Forest carbon sink density was higher in China than that in the continental U.S., mainly due to a larger fraction of young forests in China. Total carbon sequestration by forests in China was close to that in the continental U.S. during the recent decade.

  1. Estimate of changes in agricultural terrestrial nitrogen pathways and ammonia emissions from 1850 to present in the Community Earth System Model

    NASA Astrophysics Data System (ADS)

    Riddick, Stuart; Ward, Daniel; Hess, Peter; Mahowald, Natalie; Massad, Raia; Holland, Elisabeth

    2016-06-01

    Nitrogen applied to the surface of the land for agricultural purposes represents a significant source of reactive nitrogen (Nr) that can be emitted as a gaseous Nr species, be denitrified to atmospheric nitrogen (N2), run off during rain events or form plant-useable nitrogen in the soil. To investigate the magnitude, temporal variability and spatial heterogeneity of nitrogen pathways on a global scale from sources of animal manure and synthetic fertilizer, we developed a mechanistic parameterization of these pathways within a global terrestrial land model, the Community Land Model (CLM). In this first model version the parameterization emphasizes an explicit climate-dependent approach while using highly simplified representations of agricultural practices, including manure management and fertilizer application. The climate-dependent approach explicitly simulates the relationship between meteorological variables and biogeochemical processes to calculate the volatilization of ammonia (NH3), nitrification and runoff of Nr following manure or synthetic fertilizer application. For the year 2000, approximately 125 Tg N yr-1 is applied as manure and 62 Tg N yr-1 is applied as synthetic fertilizer. We estimate the resulting global NH3 emissions are 21 Tg N yr-1 from manure (17 % of manure production) and 12 Tg N yr-1 from fertilizer (19 % of fertilizer application); reactive nitrogen runoff during rain events is calculated as 11 Tg N yr-1 from manure and 5 Tg N yr-1 from fertilizer. The remaining nitrogen from manure (93 Tg N yr-1) and synthetic fertilizer (45 Tg N yr-1) is captured by the canopy or transferred to the soil nitrogen pools. The parameterization was implemented in the CLM from 1850 to 2000 using a transient simulation which predicted that, even though absolute values of all nitrogen pathways are increasing with increased manure and synthetic fertilizer application, partitioning of nitrogen to NH3 emissions from manure is increasing on a percentage basis, from

  2. Using (137)Cs and (210)Pbex and other sediment source fingerprints to document suspended sediment sources in small forested catchments in south-central Chile.

    PubMed

    Schuller, P; Walling, D E; Iroumé, A; Quilodrán, C; Castillo, A; Navas, A

    2013-10-01

    A study of the impact of forest harvesting operations on sediment mobilization from forested catchments has been undertaken in south-central Chile. The study focused on two sets of small paired catchments (treatment and control), with similar soil type, but contrasting mean annual rainfall, located about 400 km apart at Nacimiento (1200 mm yr(-1)) and Los Ulmos (2500 mm yr(-1)). The objective was to study the changes in the relative contribution of the primary sources of fine sediment caused by forestry operations. Attention focused on the pre-harvest and post-harvest periods and the post-replanting period was included for the Nacimiento treatment catchment. The sediment source fingerprinting technique was used to document the contributions of the potential sources. Emphasis was placed on discriminating between the forest slopes, forest roads and channel erosion as potential sources of fine sediment and on assessing the relative contributions of these three sources to the sediment yield from the catchments. The fallout radionuclides (FRNs) (137)Cs and excess lead-210, the environmental radionuclides (226)Ra and (40)K and soil organic matter (SOM) were tested as possible fingerprints for discriminating between potential sediment sources. The Kruskal-Wallis test and discriminant function analysis were used to guide the selection of the optimum fingerprint set for each catchment and observation period. Either one or both of the FRNs were selected for inclusion in the optimum fingerprint for all datasets. The relative contribution of each sediment source to the target sediment load was estimated using the selected fingerprint properties, and a mixing model coupled with a Monte Carlo simulation technique that takes account of uncertainty in characterizing sediment source properties. The goodness of fit of the mixing model was tested by comparing the measured and simulated fingerprint properties for the target sediment samples. In the Nacimiento treatment catchment

  3. Probing the formation of intermediate- to high-mass stars in protoclusters. A detailed millimeter study of the NGC 2264 clumps

    NASA Astrophysics Data System (ADS)

    Peretto, N.; André, Ph.; Belloche, A.

    2006-01-01

    We present the results of dust continuum and molecular line observations of two massive cluster-forming clumps, NGC 2264-C and NGC 2264-D, including extensive mapping performed with the MAMBO bolometer array and the HERA heterodyne array on the IRAM 30 m telescope. Both NGC 2264 clumps are located in the Mon OB1 giant molecular cloud complex, adjacent to one another. Twelve and fifteen compact millimeter continuum sources (i.e. MMSs) were identified in clumps C and D, respectively. These MMSs have larger sizes and masses than the millimeter continuum condensations detected in well-known nearby protoclusters such as ρ Ophiuchi. The MMSs of NGC 2264 are closer in size to the DCO+ "cores" of ρ Oph, although they are somewhat denser and exhibit broader linewidths. Most of the MMSs of NGC 2264-C harbor candidate Class 0 protostars associated with shocked molecular hydrogen jets. Evidence of widespread infall motions was found in, e.g., HCO^+(3-2) or CS(3-2) in both NGC 2264-C and NGC 2264-D. A sharp velocity discontinuity 2 km s-1 in amplitude was observed in N2H^+(1-0) and H13CO^+(1-0) in the central, innermost part of NGC 2264-C, which we interpreted as the signature of a strong dynamical interaction between two MMSs and their possible merging with the central MMS C-MM3. Radiative transfer modelling supports the idea that NGC 2264-C is a highly unstable prolate clump in the process of collapsing along its long axis on a near free-fall dynamical timescale 1.7 × 10 5 yr. Our model fit of this large-scale collapse suggests a maximum mass inflow rate 3× 10-3 M⊙ yr-1 toward the central protostellar object C-MM3. In NGC 2264-D, we estimated a mass infall rate dot{M}_DMM1 ˜ 1.1 × 10 -4 M⊙ yr-1 toward the rotating Class 0 object D-MM1, also based on radiative transfer modelling of the observations. Such infall rates are sufficiently high to overcome radiation pressure and allow the formation of 20 M⊙ stars by accretion in 1.7× 105 yr, i.e., a time that is similar

  4. Hubble Space Telescope WFPC2 Study of the Trapezium Cluster: The Influence of Circumstellar Disks on the Initial Mass Function

    NASA Astrophysics Data System (ADS)

    Robberto, M.; Song, J.; Mora Carrillo, G.; Beckwith, S. V. W.; Makidon, R. B.; Panagia, N.

    2004-05-01

    We have performed the first measures of mass accretion rates in the core of the Orion Nebula Cluster. Four adjacent fields centered on the Trapezium stars have been imaged in the U and B bands using the Wide Field Planetary Camera 2 (WFPC2) on board the Hubble Space Telescope. We obtained photometry for 91 stars in the U band (F336W) and 71 stars in the B band (F439W). The WFPC2 archive was also searched to obtain complementary V-band (F547M) and I-band (F791W) photometry. In this paper we focus our attention on a group of 40 stars with known spectral types and complete UBVI WFPC2 photometry. We locate each star on the H-R diagram, considering both the standard ISM reddening law with RV=3.1 and the ``anomalous'' reddening law with RV=5.5 more appropriate for the Orion Nebula. Then we derive the stellar masses and ages by comparing with the evolutionary tracks and isochrones calculated by D'Antona & Mazzitelli and Palla & Stahler. Approximately three-quarters of the sources show excess luminosity in the U band, which we attribute to mass accretion. The known correlation between the U-band excess and the total accretion luminosity, recalibrated for our photometric system, allows us to estimate the accretion rates, which are all found to be in the range 10-8 to 10-12 Msolar yr-1. For stars older than 1 Myr, there is some evidence of a relation between mass accretion rates and stellar age. Overall, mass accretion rates appear lower than those measured by other authors in the Orion flanking fields or in Taurus-Auriga. Mass accretion rates remain low even in the vicinity of the 10-5 Msolar yr-1 birth line of Palla & Stahler, suggesting that in the core of the Trapezium cluster, disk accretion has been recently depressed by an external mechanism. We suggest that the UV radiation generated by the Trapezium OB stars, responsible for the disk evaporation, may also cause the drop of the mass accretion rate. In this scenario, low-mass stars may terminate their pre

  5. On the physical structure of IRC +10216. Ground-based and Herschel observations of CO and C2H

    NASA Astrophysics Data System (ADS)

    De Beck, E.; Lombaert, R.; Agúndez, M.; Daniel, F.; Decin, L.; Cernicharo, J.; Müller, H. S. P.; Min, M.; Royer, P.; Vandenbussche, B.; de Koter, A.; Waters, L. B. F. M.; Groenewegen, M. A. T.; Barlow, M. J.; Guélin, M.; Kahane, C.; Pearson, J. C.; Encrenaz, P.; Szczerba, R.; Schmidt, M. R.

    2012-03-01

    Context. The carbon-rich asymptotic giant branch star IRC +10 216 undergoes strong mass loss, and quasi-periodic enhancements of the density of the circumstellar matter have previously been reported. The star's circumstellar environment is a well-studied and complex astrochemical laboratory, in which many molecular species have been proved to be present. CO is ubiquitous in the circumstellar envelope, while emission from the ethynyl (C2H) radical is detected in a spatially confined shell around IRC +10 216. We recently detected unexpectedly strong emission from the N = 4-3, 6-5, 7-6, 8-7, and 9-8 transitions of C2H with the IRAM 30 m telescope and with Herschel/HIFI, which challenges the available chemical and physical models. Aims: We aim to constrain the physical properties of the circumstellar envelope of IRC +10 216, including the effect of episodic mass loss on the observed emission lines. In particular, we aim to determine the excitation region and conditions of C2H to explain the recent detections and to reconcile them with interferometric maps of the N = 1-0 transition of C2H. Methods: Using radiative-transfer modelling, we provide a physical description of the circumstellar envelope of IRC +10 216, constrained by the spectral-energy distribution and a sample of 20 high-resolution and 29 low-resolution CO lines - to date, the largest modelled range of CO lines towards an evolved star. We furthermore present the most detailed radiative-transfer analysis of C2H that has been done so far. Results: Assuming a distance of 150 pc to IRC +10 216, the spectral-energy distribution was modelled with a stellar luminosity of 11300 L⊙ and a dust-mass-loss rate of 4.0 × 10-8 M⊙ yr-1. Based on the analysis of the 20 high-frequency-resolution CO observations, an average gas-mass-loss rate for the last 1000 years of 1.5 × 10-5 M⊙ yr-1 was derived. This results in a gas-to-dust-mass ratio of 375, typical for this type of star. The kinetic temperature throughout the

  6. The Accretion Rates and White Dwarf Components of Nova-Like Cataclysmic Variables

    NASA Astrophysics Data System (ADS)

    Mizusawa, Trisha; Merritt, J.; Bonaro, M.; Foran, S.; Plumberg, C.; Stewart, H.; Wiley, T.; Ballouz, R.; Sion, E.

    2009-01-01

    We present the results of a multi-component synthetic spectral analysis of the archival far ultraviolet spectra of several key nova-like variables including members of the SW Sex, RW Tri, UX UMa and VY Scl subclasses: KR Aur, V795 Her, BP Lyn, V825 Her, HL Aqr, RW Tri and V425 Cas. Accretion rates as well as the flux contribution of the accreting white dwarf are included in our analysis. Except for RW Tri which has a reliable trigonometric parallax, we computed the distances to the nova-like systems using the method of Knigge(2006, MNRAS, 373, 484). For KR Aur, we find that the white dwarf has T_eff = 29,000 +/- 2000K, log g = 8.4 and contributes 18% of the FUV flux while an accretion disk with accretion rate Mdot = 3 x 10-10 Msun/yr at an inclination of 41 degrees, contributes the remainder. Our analysis of seven archival IUE spectra of RW Tri at its parallax distance consistently yields a low mass (0.4 Msun) white dwarf and an average accretion rate, Mdot = 6.3 x 10-9 Msun/yr. We find that an accreting white dwarf rather than accretion disk dominates the far UV spectrum of V425 Cas while HL Aqr's and V825 Her's FUV spectra are dominated by an accretion disk with Mdot = 1 x 10-9 Msun/yr and 3 x 10-9 Msun/yr, respectively. For BP Lyn we find Mdot = 1 x 10-8 Msun/yr and we explore the possiblity that V795 Her is an intermediate polar. We discuss the implications of our results for the evolutionary status of nova-like variables. This work is supported by NSF grant AST-0807892 to Villanova University and by the Delaware Space Grant Consortium

  7. The evolution of the equivalent width of the Hα emission line and specific star formation rate in star-forming galaxies at 1 < z < 5

    NASA Astrophysics Data System (ADS)

    Mármol-Queraltó, E.; McLure, R. J.; Cullen, F.; Dunlop, J. S.; Fontana, A.; McLeod, D. J.

    2016-08-01

    We present the results of a study which uses spectral energy distribution (SED) fitting to investigate the evolution of the equivalent width (EW) of the Hα emission line in star-forming galaxies over the redshift interval 1 < z < 5. After first demonstrating the ability of our SED-fitting technique to recover EW(Hα) using a sample of galaxies at z ≃ 1.3 with EW(Hα) measurements from 3D-HST grism spectroscopy, we proceed to apply our technique to samples of spectroscopically confirmed and photometric-redshift selected star-forming galaxies at z ≥ 1 in the CANDELS (Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey) UDS and GOODS-S fields. Confining our analysis to a constant stellar mass range (9.5 < log (M⋆/M⊙) < 10.5), we find that the median EW(Hα) evolves only modestly with redshift, reaching a rest-frame value of EW(Hα) =301 ± 30 Å by redshift z ≃ 4.5. Furthermore, using estimates of star formation rate (SFR) based on both UV luminosity and Hα line flux, we use our galaxy samples to compare the evolution of EW(Hα) and specific star formation rate (sSFR). Our results indicate that over the redshift range 1 < z < 5, the evolution displayed by EW(Hα) and sSFR is consistent, and can be adequately parametrized as ∝ (1 + z)1.0 ± 0.2. As a consequence, over this redshift range, we find that the sSFR and rest-frame EW(Hα) of star-forming galaxies with stellar masses M⋆ ≃ 10^{10}{ M_{sun;} are related by EW(Hα)/Å = (63 ± 7) × sSFR/Gyr-1. Given the current uncertainties in measuring the SFRs of high-redshift galaxies, we conclude that EW(Hα) provides a useful independent tracer of sSFR for star-forming galaxies out to redshifts of z = 5.

  8. HOPS + MALT90 + Hi-GAL: Probing star formation on a Galactic scale through mm molecular line and far-IR continuum Galactic plane surveys

    NASA Astrophysics Data System (ADS)

    Longmore, Steven N.; Rathborne, Jill; Bastian, Nate; Alves, Joao; Ascenso, Joana; Bally, John; Testi, Leonardo; Longmore, Andy; Battersby, Cara; Bressert, Eli; Purcell, Cormac; Walsh, Andrew; Jackson, James; Foster, Jonathan; Molinari, Sergio; Meingast, Stefan; Amorim, A.; Lima, J.; Marques, R.; Moitinho, A.; Pinhao, J.; Rebordao, J.; Santos, F. D.

    2012-03-01

    With the HOPS and MALT90 Galactic plane surveys we are mapping a significant fraction of the dense molecular gas in the Galaxy in over 20 dense-gas-tracing transitions (e.g. from H2O, NH3, HC3N, HC5N, N2H+, HCN, HNC, HCO+, CH3CN, SiO, C2H, ...). Combining this with the far-IR continuum emission from Hi-GAL we can derive the physical/chemical/kinematic properties and evolutionary state of much of the molecular gas in the Galaxy destined to form stars. I will present results from three science projects based on this combined dataset, namely: i) looking for variations in the star formation rate across the Galaxy as a function of environment, in particular, comparing the CMZ with the rest of the Galactic disk -- we find the rate of star formation per unit mass of dense gas in the CMZ may be an order of magnitude lower than that in the disk; ii) seeing if Galactic dense molecular clouds follow the empirical relations observed in extragalactic systems (e.g. the Kennicutt-Schmidt and Gao & Solomon relations) and what this implies for interpretating the extragalactic relations; iii) searching for molecular cloud progenitors of the most extreme (massive and dense) stellar clusters. I will present one cloud we have studied as part of project iii) which lies close to the Galactic center and which is clearly extreme compared to the rest of the Galactic molecular cloud population. With a mass of 10^5 Msun, a radius of only ~3pc and almost no signs of star formation it appears to be the progenitor of an Arches-like stellar cluster. As such, we speculate this molecular cloud may be a local-universe-analogue of the initial conditions of a super star cluster or potentially even a small globular cluster. From our Galactic plane survey data this object appears to be unique in the Galaxy, making it extremely important for testing massive cluster formation models. We have been awarded 6 hours of ALMA Cycle 0 observing time to study this object in detail and I hope to show preliminary

  9. Formation of the first galaxies under Population III stellar feedback

    NASA Astrophysics Data System (ADS)

    Jeon, Myoungwon

    2015-01-01

    The first galaxies, which formed a few hundred million years after the big bang, are related to important cosmological questions. Given thatthey are thought to be the basic building blocks of large galaxies seen today, understanding their formation and properties is essentialto studying galaxy formation as a whole. In this dissertation talk, I will present the results of our highly-resolved cosmological ab-initio simulations to understand the assembly process of first galaxies under the feedback from the preceding generations of first stars, the so-called Population III (Pop III). The first stars formed at z≲30 in dark matter (DM) minihalos with M_{vir}=10^5-10^6Msun, predominately via molecular hydrogen (H_2) cooling. Radiation from Pop III stars dramatically altered the gas within their host minihalos, through photoionization, photoheating, and photoevaporation. Once a Pop III star explodes as a supernova (SN), heavy elements are dispersed, enriching the interstellar (ISM) and intergalactic medium (IGM), thus initiating the process of chemical evolution. I will begin by presenting how the SN explosion of the first stars influences early cosmic history, specifically assessing the time delay in further star formation and tracing the evolution of metal-enriched gas until the second episode star formation happens. These results will show the role of Pop III supernovae on the star formation transition from Pop III to Population II. Additionally, the more distant, diffuse IGM was heated by X-rays emitted by accreting black holes (BHs), or high-mass X-ray binaries (HMXBs), both remnants of Pop III stars. I will present results of a series of simulations where we study the impact of X-ray feedback from BHs and HMXBs on the star formation history in the early universe, and discuss the resulting implications on reionization. I will also present the role of X-rays on the early BH growth, providing constraints on models for supermassive black hole formation. Finally, I

  10. Water emission in NGC 1333-IRAS 4. The physical structure of the envelope

    NASA Astrophysics Data System (ADS)

    Maret, S.; Ceccarelli, C.; Caux, E.; Tielens, A. G. G. M.; Castets, A.

    2002-11-01

    We report ISO-LWS far infrared observations of CO, water and oxygen lines towards the protobinary system IRAS 4 in the NGC 1333 cloud. We detected several water, OH, CO rotational lines, and two [OI] and [CII] fine structure lines. Given the relatively poor spectral and spatial resolution of these observations, assessing the origin of the observed emission is not straightforward. In this paper, we focus on the water line emission and explore the hypothesis that it originates in the envelopes that surround the two protostars, IRAS 4 A and B, thanks to an accurate model. The model reproduces quite well the observed water line fluxes, predicting a density profile, mass accretion rate, central mass, and water abundance profile in agreement with previous works. We hence conclude that the emission from the envelopes is a viable explanation for the observed water emission, although we cannot totally rule out the alternative that the observed water emission originates in the outflow. The envelopes are formed by a static envelope where the density follows the r-2 law, at r >= 1500 AU, and a collapsing envelope where the density follows the r-3/2 law. The density of the envelopes at 1500 AU from the center is ~ 4 x 106 cm-3 and the dust temperature is ~ 30 K, i.e. about the evaporation temperature of CO-rich ices. This may explain previous observations that claimed a factor of 10 depletion of CO in IRAS 4, as those observations probe the outer <=30 K region of the envelope. The water is ~ 5 x 10-7 less abundant than H2 in the outer and cold envelope, whereas its abundance jumps to ~ 5 x 10-6 in the innermost warm region, at r<= 80 AU where the dust temperature exceeds 100 K, the evaporation temperature of H2O-rich ices. We derive a mass of 0.5 Msun for each protostar, and an accretion rate of 5 x 10-5 Msunyr, implying an age of about 10000 years, if the accretion rate remains constant. We finally discuss the difference between IRAS 4 and IRAS 16293-2422, where a similar

  11. Physical Parameters of the Overcontact Binary AH Cnc in the Old Open Cluster M 67

    NASA Astrophysics Data System (ADS)

    Yakut, K.; Aerts, C.

    2006-04-01

    We present a photometric study of the overcontact binary AH Cnc. The CCD observations were done with the Russian-Turkish 1.5 m telescope and the light-curve was solved with the Wilson-Devinney code. The physical parameters of the components have been deduced as M1 = 1.22 Msun, M2 = 0.20 Msun, R1 = 1.37 Rsun, R2 = 0.66 Rsun, L1 = 2.65 Lsun and L2 = 0.63 Lsun from the obtained orbital parameters and the distance modules of M 67. AH Cnc has been compared with similar systems in the Hertzsprung-Russell diagram.

  12. Impacts of recent climate change on dry-land crop water consumption in the northern agro-pastoral transitional zone of China

    NASA Astrophysics Data System (ADS)

    Zhao, Lingyu; Liu, Yaling; Pan, Zhihua; An, Pingli; Pan, Xuebiao; Zhao, Peiyi

    2013-08-01

    Climate change has substantially impacted crop growth and development in the northern agro-pastoral transitional zone. Examination of the response of crop water consumption to climate change may provide a guide for adapting local agricultural production and ecological construction to new realities. The water consumption of three local crops (wheat, naked oats, and potatoes) is examined for Wuchuan County in the northern agro-pastoral transitional zone of China using meteorological data from 1960 to 2007 and soil moisture data from 1983 to 2007. The relationships between climate change and the crop water consumption are discussed. The results show that Wuchuan experienced both a warming trend and a reduction of precipitation between 1960 and 2007. The annual mean surface air temperature increased at a rate of 0.04°C yr-1 and the annual precipitation decreased at a rate of 0.7 mm yr-1. Both trends are particularly pronounced between 1983 and 2007, with an increase in annual mean temperature of 0.09°C yr-1 and a decrease in annual mean precipitation of 2.1 mm yr-1. Crop water consumption decreased between 1983 and 2007 for wheat (1.65 mm yr-1), naked oats (2.04 mm yr-1), and potatoes (3.85 mm yr-1). Potatoes and naked oats consume more water than wheat. Climate change has significantly impacted crop water consumption. Water consumption and rainfall during the growing season are positively correlated, while water consumption and active accumulated temperature are negatively correlated. Compared to precipitation, accumulated temperature has little impact on crop water consumption. Recent climate change has been detrimental for crop production in Wuchuan County. Adaptation to climate change should include efforts to breed drought-resistant crops and to develop drought-resistant cultivation techniques.

  13. The Carbon Budget of Coastal Waters of Eastern North America

    NASA Astrophysics Data System (ADS)

    Najjar, R.; Boyer, E. W.; Burdige, D.; Butman, D. E.; Cai, W. J.; Canuel, E. A.; Chen, R. F.; Friedrichs, M. A.; Griffith, P. C.; Herrmann, M.; Kemp, W. M.; Kroeger, K. D.; Mannino, A.; McCallister, S. L.; McGillis, W. R.; Mulholland, M. R.; Salisbury, J.; Signorini, S. R.; Tian, H.; Tzortziou, M.; Vlahos, P.; Wang, A. Z.; Zimmerman, R. C.; Pilskaln, C. H.

    2015-12-01

    Observations and the output of numerical and statistical models are synthesized to construct a carbon budget of the coastal waters of eastern North America. The domain extends from the head of tide to (roughly) the continental shelf break and from southern Florida to southern Nova Scotia. The domain area is 2% tidal wetlands, 19% estuarine open water, and 78% shelf water. Separate budgets are constructed for inorganic and organic carbon; for tidal wetlands, estuaries, and shelf waters; and for three main subregions: the Gulf of Maine, the Mid-Atlantic Bight, and the South Atlantic Bight. Net primary production for the study region is about 150 Tg C yr-1, with 12% occurring in tidal wetlands and 7% in estuaries. Though respiration and photosynthesis are nearly balanced in most systems and regions, tidal wetlands and shelf waters are each found to be net autotrophic whereas estuaries are net heterotrophic. The domain as a whole is a sink of 5 Tg C yr-1 of atmospheric CO2, with tidal wetlands and shelf waters taking up 10 Tg C yr-1 (split roughly equally) and estuaries releasing 5 Tg C yr-1 to the atmosphere. Carbon burial is about 3 Tg C yr-1, split roughly equally among tidal wetlands, estuaries, and shelf waters. Rivers supply 6-7 Tg C yr-1 to estuaries, about 2/3 of which is organic. Tidal wetlands supply an additional 4 Tg C yr-1 to estuaries, about half of which is organic. Carbon in organic and inorganic forms is exported from estuaries to shelf waters and from shelf waters to the open ocean. In summary, tidal wetlands and estuaries, though small in area, contribute substantially to the overall carbon budget of the region.

  14. Net greenhouse gas balance in China's Croplands over the last three decades and its mitigation potential.

    PubMed

    Zhang, Wen; Yu, Yongqiang; Li, Tingting; Sun, Wenjuan; Huang, Yao

    2014-01-01

    Cropland soils have been shown to emit nitrous oxide (N2O) and methane (CH4) into the atmosphere and to sequester carbon when field management is improved, yet the spatiotemporal changes in the N2O and CH4 emissions and the soil organic carbon (SOC) in China's croplands are unclear with regard to an integrated global warming potential (GWP). This limits our overall evaluation of anthropogenic greenhouse gas (GHG) emissions and impairs effective decision making. On the basis of model simulations primarily from 1980 to 2009, we estimated a 69% increase in the gross GWP of CH4 and N2O emissions, from 244 Tg CO2-equiv yr(-1) in the early 1980s to 413 Tg CO2-equiv yr(-1) in the late 2000s. The SOC was estimated to have increased from 54 Tg CO2-equiv yr(-1) to 117 Tg CO2-equiv yr(-1) during the same period. A reduction in the carbon input during the rice season, along with an improvement of synthetic nitrogen use efficiency in crops to 40%, would mitigate GHG emissions by 111 Tg CO2-equiv yr(-1) and keep SOC sequestration at 82 Tg CO2 yr(-1). Together, this would amount to a reduction of 193 Tg CO2-equiv yr(-1), representing ∼47% of the gross GWP in the late 2000s. The mitigation of GHG emissions in Henan, Shandong, Hunan, Jiangsu, Hubei, Sichuan, Anhui, Jiangxi, Guangdong and Hebei Provinces could lead to a ∼66% national improvement and should be given priority.

  15. O 2 reduction and denitrification rates in shallow aquifers

    USGS Publications Warehouse

    Tesoriero, A.J.; Puckett, L.J.

    2011-01-01

    O 2 reduction and denitrification rates were determined in shallow aquifers of 12 study areas representing a wide range in sedimentary environments and climatic conditions. Zero-and first-order rates were determined by relating reactant or product concentrations to apparent groundwater age. O 2 reduction rates varied widely within and between sites, with zero-order rates ranging from <3 ??mol L -1 yr -1 to more than 140 ??mol L -1 yr -1 and first-order rates ranging from 0.02 to 0.27 yr -1. Moderate denitrification rates (10-100 ??mol N L -1 yr -1; 0.06-0.30 yr -1) were observed in most areas with O 2 concentrations below 60 mol L -1, while higher rates (>100 mol N L -1 yr -1; >0.36 yr -1) occur when changes in lithology result in a sharp increase in the supply of electron donors. Denitrification lag times (i.e., groundwater travel times prior to the onset of denitrification) ranged from <20 yr to >80 yr. The availability of electron donors is indicated as the primary factor affecting O 2 reduction rates. Concentrations of dissolved organic carbon (DOC) and/or sulfate (an indicator of sulfide oxidation) were positively correlated with groundwater age at sites with high O 2 reduction rates and negatively correlated at sites with lower rates. Furthermore, electron donors from recharging DOC are not sufficient to account for appreciable O 2 and nitrate reduction. These relations suggest that lithologic sources of DOC and sulfides are important sources of electrons at these sites but surface-derived sources of DOC are not. A review of published rates suggests that denitrification tends to occur more quickly when linked with sulfide oxidation than with carbon oxidation. copyright 2011 by the American Geophysical Union.

  16. Historical atmospheric mercury emissions and depositions in North America compared to mercury accumulations in sedimentary records

    NASA Astrophysics Data System (ADS)

    Pirrone, Nicola; Allegrini, Ivo; Keeler, Gerald J.; Nriagu, Jerome O.; Rossmann, Ronald; Robbins, John A.

    Gold and silver production in North America (included United States, Canada and Mexico) released a large amount of mercury to the atmosphere until well into this century when mercury (Hg) amalgamation was replaced by cyanide concentration. Since then, emissions from industries have been the dominant anthropogenic sources of atmospheric Hg in North America as a whole. Past Hg emissions from gold and silver extractions in North America during the 1800s do not show a clear evidence of atmospheric deposition occurred at the coring sites considered in this study. Estimated atmospheric emissions of Hg in North America peaked in 1879 (at about 1708 t yr -1) and 1920 (at about 940 t yr -1), primarily due to Hg emissions from gold and silver mining. After the Great Economic Depression (1929) Hg emissions peaked again in the 1947 (274 t yr -1), in 1970 (325 t yr -1) and in 1989 (330 t yr -1) as result of increased Hg emissions from industrial sources, though improvements in the emissions control technology in United States and Canada have been substantial. Estimates of total atmospheric deposition fluxes of Hg to water and terrestrial receptors were in the range of 14.3-19.8 μg m -2 yr -1 in North America as a whole, and averaged 135 μg m -2 yr -1 (global background + local emissions) in the Great Lakes. These values were in good agreement with recent estimates reported in literature. The comparison of atmospheric Hg deposition fluxes with Hg accumulation rates in sediment cores suggests that atmospheric deposition was the major source of Hg entering the lakes system at coring sites, however, important contributions to Lake Ontario sediment cores sites from 1940 to 1970 were likely originated from local point sources (i.e. direct discharges).

  17. Multiyear Precipitation Reduction Strongly Decreases Carbon Uptake over Northern China

    NASA Astrophysics Data System (ADS)

    Yuan, Wenping

    2014-05-01

    Drought has been a concern in global and regional water, carbon and energy cycles. From 1999-2011, Northern China experienced a multiyear precipitation reduction that significantly decreased water availability as indicated by the Palmer Drought Severity Index and soil moisture measurements. In this study, a light use efficiency model (EC-LUE) and an ecosystem physiological model (IBIS) were used to characterize the impacts of long-term drought on terrestrial carbon fluxes in Northern China. EC-LUE and IBIS models showed that the reduction of averaged GPP of 0.09 and 0.05 Pg C yr-1 during 1999-2011 compared with 1982-1998. Based on the IBIS model, simulated ecosystem respiration underwent an insignificant decrease from 1999-2011. The multiyear precipitation reduction changed the regional carbon uptake of 0.011 Pg C yr-1 from 1982-1998 to a net source of 0.018 Pg C yr-1 from 1999-2011, and the ecosystem during the 13 years (1999 to 2011) released 0.23 Pg C to atmosphere which is 1.31 times that total carbon sink of 17 years prior to 1998 (0.18 Pg C). Moreover, a pronounced decrease in maize yield in almost all provinces in the study region was found from 1999-2011 versus the average of yield from1978-2011. The largest maize yield reduction occurred in Beijing (2499 kg ha-1 yr-1), Jilin (2180 kg ha-1 yr-1), Tianjing (1923 kg ha-1 yr-1) and Heilongjiang (1791 kg ha-1 yr-1), and the maize yield anomaly was significantly correlated with the annual precipitation over the entire study area. Our results revealed that recent climate change, especially drought-induced water stress, is the dominant cause of the reduction in the terrestrial carbon sink over Northern China.

  18. Multiyear precipitation reduction strongly decreases carbon uptake over northern China

    NASA Astrophysics Data System (ADS)

    Yuan, Wenping; Liu, Dan; Dong, Wenjie; Liu, Shuguang; Zhou, Guangsheng; Yu, Guirui; Zhao, Tianbao; Feng, Jinming; Ma, Zhuguo; Chen, Jiquan; Chen, Yang; Chen, Shiping; Han, Shijie; Huang, Jianping; Li, Linghao; Liu, Huizhi; Liu, Shaoming; Ma, Mingguo; Wang, Yanfeng; Xia, Jiangzhou; Xu, Wenfang; Zhang, Qiang; Zhao, Xinquang; Zhao, Liang

    2014-05-01

    Drought has been a concern in global and regional water, carbon, and energy cycles. From 1999 to 2011, northern China experienced a multiyear precipitation reduction that significantly decreased water availability as indicated by the Palmer Drought Severity Index and soil moisture measurements. In this study, a light use efficiency model (EC-LUE) and an ecosystem physiological model (IBIS) were used to characterize the impacts of long-term drought on terrestrial carbon fluxes in northern China. EC-LUE and IBIS models showed the reduction of averaged GPP of 0.09 and 0.05 Pg C yr-1 during 1999-2011 compared with 1982-1998. Based on the IBIS model, simulated ecosystem respiration experienced an insignificant decrease from 1999 to 2011. The multiyear precipitation reduction changed the regional carbon uptake of 0.011 Pg C yr-1 from 1982 to 1998 to a net source of 0.018 Pg C yr-1 from 1999 to 2011. Moreover, a pronounced decrease in maize yield in almost all provinces in the study region was found from 1999 to 2011 versus the average of yield from1978 to 2011. The largest maize yield reduction occurred in Beijing (2499 kg ha-1 yr-1), Jilin (2180 kg ha-1 yr-1), Tianjing (1923 kg ha-1 yr-1), and Heilongjiang (1791 kg ha-1 yr-1), and the maize yield anomaly was significantly correlated with the annual precipitation over the entire study area. Our results revealed that recent climate change, especially drought-induced water stress, is the dominant cause of the reduction in the terrestrial carbon sink over northern China.

  19. A global water cycle reanalysis (2003-2012) merging satellite gravimetry and altimetry observations with a hydrological multi-model ensemble

    NASA Astrophysics Data System (ADS)

    van Dijk, A. I. J. M.; Renzullo, L. J.; Wada, Y.; Tregoning, P.

    2014-08-01

    We present a global water cycle reanalysis that merges water balance estimates derived from the Gravity Recovery And Climate Experiment (GRACE) satellite mission, satellite water level altimetry and off-line estimates from several hydrological models. Error estimates for the sequential data assimilation scheme were derived from available uncertainty information and the triple collocation technique. Errors in four GRACE storage products were estimated to be 11-12 mm over land areas, while errors in monthly storage changes derived from five global hydrological models were estimated to be 17-28 mm. Prior and posterior water storage estimates were evaluated against independent observations of river water level and discharge, snow water storage and glacier mass loss. Data assimilation improved or maintained agreement overall, although results varied regionally. Uncertainties were greatest in regions where glacier mass loss and subsurface storage decline are both plausible but poorly constrained. We calculated a global water budget for 2003-2012. The main changes were a net loss of polar ice caps (-342 Gt yr-1) and mountain glaciers (-230 Gt yr-1), with an additional decrease in seasonal snowpack (-18 Gt yr-1). Storage increased due to new impoundments (+16 Gt yr-1), but this was compensated by decreases in other surface water bodies (-10 Gt yr-1). If the effect of groundwater depletion (-92 Gt yr-1) is considered separately, subsurface water storage increased by +202 Gt yr-1 due particularly to increased wetness in northern temperate regions and in the seasonally wet tropics of South America and southern Africa. The reanalysis results are publicly available via www.wenfo.org/wald/.

  20. Net greenhouse gas balance in China's Croplands over the last three decades and its mitigation potential.

    PubMed

    Zhang, Wen; Yu, Yongqiang; Li, Tingting; Sun, Wenjuan; Huang, Yao

    2014-01-01

    Cropland soils have been shown to emit nitrous oxide (N2O) and methane (CH4) into the atmosphere and to sequester carbon when field management is improved, yet the spatiotemporal changes in the N2O and CH4 emissions and the soil organic carbon (SOC) in China's croplands are unclear with regard to an integrated global warming potential (GWP). This limits our overall evaluation of anthropogenic greenhouse gas (GHG) emissions and impairs effective decision making. On the basis of model simulations primarily from 1980 to 2009, we estimated a 69% increase in the gross GWP of CH4 and N2O emissions, from 244 Tg CO2-equiv yr(-1) in the early 1980s to 413 Tg CO2-equiv yr(-1) in the late 2000s. The SOC was estimated to have increased from 54 Tg CO2-equiv yr(-1) to 117 Tg CO2-equiv yr(-1) during the same period. A reduction in the carbon input during the rice season, along with an improvement of synthetic nitrogen use efficiency in crops to 40%, would mitigate GHG emissions by 111 Tg CO2-equiv yr(-1) and keep SOC sequestration at 82 Tg CO2 yr(-1). Together, this would amount to a reduction of 193 Tg CO2-equiv yr(-1), representing ∼47% of the gross GWP in the late 2000s. The mitigation of GHG emissions in Henan, Shandong, Hunan, Jiangsu, Hubei, Sichuan, Anhui, Jiangxi, Guangdong and Hebei Provinces could lead to a ∼66% national improvement and should be given priority. PMID:24512240

  1. Evaluation Of Elastic Strain Accumulation In The Southern Indian Peninsula By GPS-Geodesy

    NASA Astrophysics Data System (ADS)

    Narayanababu, R.; Ec, M.; Tummala, C.

    2004-12-01

    The computed elastic strain accumulation in the southern Indian peninsula from the GPS derived velocity fields of the global network of GPS stations, in and around the Indian plate which includes Maitri, Indian Antarctic Station, show a significant departure from rigid plate behaviour in a manner consistent with the mapped intra plate stress field, observations of deformations and seismicity in the region. Our results of intraplate strain accumulation within Antarctica Plate covering three sites MAIT, CAS1 and DAV1 are 1.8x10-9yr-1, 1.6x10-9yr-1 and 1.1x10-9yr-1, respectively. Similarly, the estimates of interplate strain accumulation between Antarctica and other plates Somalia (SEY1), Africa (HARO), Australia (YAR1), and diffuse plate boundary between India and Australia (COCO) are found to be 1.1x10-9yr-1, 1.0x10-10yr-1, 1.27x10-8yr-1 and 1.18x10-8yr-1, respectively. These estimates are in good agreement with the earlier studies on estimation of global strain rate. The combined GPS and seismic analysis confirm the emergence of diffuse plate boundary between India and Australia and relates to the late Miocene Himalayan uplift. The calculated stress field in the West of the Indian Peninsula has a roughly N-S directed tensional and E-W oriented compressional character and the velocity vectors of all other sites throw a significant insight into the plausible causes of the strain accumulation processes in the Indian Ocean and the northward movement of Indian plate.

  2. Natural and anthropogenic methane sources in New England

    NASA Astrophysics Data System (ADS)

    Blaha, D.; Bartlett, K.; Czepiel, P.; Harriss, R.; Crill, P.

    We have recently completed a methane emissions inventory for the New England region. Methane emissions were calculated to be 0.91 Tg yr -1, with wetlands and landfills dominating all other sources. Wetlands are estimated to produce 0.33 Tg CH 4 yr -1, of which 74% come from Maine. Active landfills emit an estimated 0.28 Tg CH 4 yr -1, 60% of which are generated from twelve landfills. Although uncertainty in the estimate is greater, emissions from closed landfills are on the same order of magnitude as active landfills and wetlands; 0.25 Tg CH 4 yr -1. Sources of moderate magnitude include ruminant animals (0.05 Tg CH 4 yr -1) and residential wood combustion (0.03 Tg CH 4 yr -1). Motor vehicles, natural gas, and wastewater treatment make only minor contributions. New England is heavily forested and the soil uptake of atmospheric methane in upland forests, 0.06 Tg CH 4 yr -1, decreases emissions from soils by about 18%. Although uncertainties remain, our estimates indicate that even in a highly urbanized region such as New England, natural sources of methane make the single greatest contribution to total emissions, with state totals varying between 8% (Massachusetts) and 92% (Maine). Because emissions from only a few large landfills dominate anthropogenic sources, mitigation strategies focused on these discrete point sources should result in significant improvements in regional air quality. Current federal regulations mandate landfill gas collection at only the largest sites. Expanding recovery efforts to moderately sized landfills through either voluntary compliance or further regulations offers the best opportunity to substantially reduce atmospheric methane in New England. In the short term, however, the large contribution from closed, poorly regulated landfills may make the attribution of air quality improvements difficult. Mitigation efforts toward these landfills should also be a priority.

  3. Dissolved inorganic carbon and alkalinity fluxes from coastal marine sediments: model estimates for different shelf environments and sensitivity to global change

    NASA Astrophysics Data System (ADS)

    Krumins, V.; Gehlen, M.; Arndt, S.; van Cappellen, P.; Regnier, P.

    2012-07-01

    We present a one-dimensional reactive transport model to estimate benthic fluxes of dissolved inorganic carbon (DIC) and alkalinity (AT) from coastal marine sediments. The model incorporates the transport processes of sediment accumulation, molecular diffusion, bioturbation and bioirrigation, while the reactions included are the redox pathways of organic carbon oxidation, re-oxidation of reduced nitrogen, iron and sulfur compounds, pore water acid-base equilibria, and dissolution of particulate inorganic carbon (calcite, aragonite, and Mg-calcite). The coastal zone is divided into four environmental units with different particulate inorganic carbon (PIC) and particulate organic carbon (POC) fluxes: reefs, banks and bays, carbonate shelves and non-carbonate shelves. Model results are analyzed separately for each environment and then scaled up to the whole coastal ocean. The model-derived estimate for the present-day global coastal benthic DIC efflux is 126 Tmol yr-1, based on a global coastal reactive POC depositional flux of 117 Tmol yr-1. The POC decomposition leads to a~carbonate dissolution from shallow marine sediments of 7 Tmol yr-1 (on the order of 0.1 Pg C yr-1). Assuming complete re-oxidation of aqueous sulfide released from sediments, the effective net flux of alkalinity to the water column is 29 Teq yr-1, primarily from PIC dissolution (46%) and ammonification (33%). Because our POC depositional flux falls in the high range of global values given in the literature, the reported DIC and alkalinity fluxes should be viewed as upper-bound estimates. Increasing coastal seawater DIC to what might be expected in year 2100 due to the uptake of anthropogenic CO2 increases PIC dissolution by 2.3 Tmol yr-1 and alkalinity efflux by 4.8 Teq yr-1. Our reactive transport modeling approach not only yields global estimates of benthic DIC, alkalinity and nutrient fluxes under variable scenarios of ocean productivity and chemistry, but also provides insights into the

  4. Dissolved inorganic carbon and alkalinity fluxes from coastal marine sediments: model estimates for different shelf environments and sensitivity to global change

    NASA Astrophysics Data System (ADS)

    Krumins, V.; Gehlen, M.; Arndt, S.; Van Cappellen, P.; Regnier, P.

    2013-01-01

    We present a one-dimensional reactive transport model to estimate benthic fluxes of dissolved inorganic carbon (DIC) and alkalinity (AT) from coastal marine sediments. The model incorporates the transport processes of sediment accumulation, molecular diffusion, bioturbation and bioirrigation, while the reactions included are the redox pathways of organic carbon oxidation, re-oxidation of reduced nitrogen, iron and sulfur compounds, pore water acid-base equilibria, and dissolution of particulate inorganic carbon (calcite, aragonite, and Mg-calcite). The coastal zone is divided into four environmental units with different particulate inorganic carbon (PIC) and particulate organic carbon (POC) fluxes: reefs, banks and bays, carbonate shelves and non-carbonate shelves. Model results are analyzed separately for each environment and then scaled up to the whole coastal ocean. The model-derived estimate for the present-day global coastal benthic DIC efflux is 126 Tmol yr-1, based on a global coastal reactive POC depositional flux of 117 Tmol yr-1. The POC decomposition leads to a carbonate dissolution from shallow marine sediments of 7 Tmol yr-1 (on the order of 0.1 Pg C yr-1. Assuming complete re-oxidation of aqueous sulfide released from sediments, the effective net flux of alkalinity to the water column is 29 Teq. yr-1, primarily from PIC dissolution (46%) and ammonification (33%). Because our POC depositional flux falls in the high range of global values given in the literature, the reported DIC and alkalinity fluxes should be viewed as upper-bound estimates. Increasing coastal seawater DIC to what might be expected in year 2100 due to the uptake of anthropogenic CO2 increases PIC dissolution by 2.3 Tmol yr-1and alkalinity efflux by 4.8 Teq. yr-1. Our reactive transport modeling approach not only yields global estimates of benthic DIC, alkalinity and nutrient fluxes under variable scenarios of ocean productivity and chemistry, but also provides insights into the

  5. 3-D GPS velocity field and its implications on the present-day post-orogenic deformation of the Western Alps and Pyrenees

    NASA Astrophysics Data System (ADS)

    Ninh Nguyen, Hai; Vernant, Philippe; Mazzotti, Stephane; Khazaradze, Giorgi; Asensio, Eva

    2016-09-01

    We present a new 3-D GPS velocity solution for 182 sites for the region encompassing the Western Alps, Pyrenees, and southern France. The velocity field is based on a Precise Point Positioning (PPP) solution, to which we apply a common-mode filter, defined by the 26 longest time series, in order to correct for network-wide biases (reference frame, unmodeled large-scale processes, etc.). We show that processing parameters, such as troposphere delay modeling, can lead to systematic velocity variations of 0.1-0.5 mm yr-1 affecting both accuracy and precision, especially for short (< 5 years) time series. A velocity convergence analysis shows that minimum time-series lengths of ˜ 3 and ˜ 5.5 years are required to reach a velocity stability of 0.5 mm yr-1 in the horizontal and vertical components, respectively. On average, horizontal residual velocities show a stability of ˜ 0.2 mm yr-1 in the Western Alps, Pyrenees, and southern France. The only significant horizontal strain rate signal is in the western Pyrenees with up to 4 × 10-9 yr-1 NNE-SSW extension, whereas no significant strain rates are detected in the Western Alps (< 1 × 10-9 yr-1). In contrast, we identify significant uplift rates up to 2 mm yr-1 in the Western Alps but not in the Pyrenees (0.1 ± 0.2 mm yr-1). A correlation between site elevations and fast uplift rates in the northern part of the Western Alps, in the region of the Würmian ice cap, suggests that part of this uplift is induced by postglacial rebound. The very slow uplift rates in the southern Western Alps and in the Pyrenees could be accounted for by erosion-induced rebound.

  6. O2 reduction and denitrification rates in shallow aquifers

    NASA Astrophysics Data System (ADS)

    Tesoriero, Anthony J.; Puckett, Larry J.

    2011-12-01

    O2 reduction and denitrification rates were determined in shallow aquifers of 12 study areas representing a wide range in sedimentary environments and climatic conditions. Zero- and first-order rates were determined by relating reactant or product concentrations to apparent groundwater age. O2 reduction rates varied widely within and between sites, with zero-order rates ranging from <3 μmol L-1 yr-1 to more than 140 μmol L-1 yr-1 and first-order rates ranging from 0.02 to 0.27 yr-1. Moderate denitrification rates (10-100 μmol N L-1 yr-1; 0.06-0.30 yr-1) were observed in most areas with O2 concentrations below 60 μmol L-1, while higher rates (>100 μmol N L-1 yr-1; >0.36 yr-1) occur when changes in lithology result in a sharp increase in the supply of electron donors. Denitrification lag times (i.e., groundwater travel times prior to the onset of denitrification) ranged from <20 yr to >80 yr. The availability of electron donors is indicated as the primary factor affecting O2 reduction rates. Concentrations of dissolved organic carbon (DOC) and/or sulfate (an indicator of sulfide oxidation) were positively correlated with groundwater age at sites with high O2 reduction rates and negatively correlated at sites with lower rates. Furthermore, electron donors from recharging DOC are not sufficient to account for appreciable O2 and nitrate reduction. These relations suggest that lithologic sources of DOC and sulfides are important sources of electrons at these sites but surface-derived sources of DOC are not. A review of published rates suggests that denitrification tends to occur more quickly when linked with sulfide oxidation than with carbon oxidation.

  7. GPS and gravity constraints on continental deformation in the Alborz mountain range, Iran

    NASA Astrophysics Data System (ADS)

    Djamour, Yahya; Vernant, Philippe; Bayer, Roger; Nankali, Hamid Reza; Ritz, Jean-François; Hinderer, Jacques; Hatam, Yaghoub; Luck, Bernard; Le Moigne, Nicolas; Sedighi, Morteza; Khorrami, Fateme

    2010-12-01

    A network of 54 survey GPS sites, 28 continuous GPS stations and three absolute gravity (AG) observation sites have been set up in the Alborz mountain range to quantify the present-day kinematics of the range. Our results allow us to accurately estimate the motion of the South Caspian block (SCB) for the first time, and indicate rotation of the SCB relative to Eurasia, accounting for the left lateral motion in the Alborz range. In light of these new results, it clearly appears that deformation rates vary along the range, the eastern part accommodating mainly left lateral strike slip (2 mm yr-1 south of the range and 5 mm yr-1 north of the range) with a very low range normal shortening rate on the Khazar thrust fault (~2 mm yr-1), and the western part accommodating range normal shortening (~6 mm yr-1) on the Khazar thrust fault with a left lateral component of ~2 mm yr-1 north of the range and 1 mm yr-1 south of the range. These present-day kinematics agree with geomorphologic estimated slip rates, but not the long-term deformation, corroborating the idea that the kinematics of the range have changed recently due to the change of SCB motion. Modelling of the interseismic deformation suggests a deep locking depth on the central-western segment of the Khazar fault (~30 km) in agreement with the Baladeh earthquake rupture and aftershock ranging between 10 and 30 km. Given this unusual deep locking depth and the 34° dip of the thrust, a large part of the Alborz range is located above the seismically coupled part of the fault. Based on our AG measurements this part of the range seems to uplift at a rate of 1-5 mm yr-1, in agreement with terrace uplift.

  8. A nitrogen budget for the Strait of Georgia, British Columbia, with emphasis on particulate nitrogen and dissolved inorganic nitrogen

    NASA Astrophysics Data System (ADS)

    Sutton, J. N.; Johannessen, S. C.; Macdonald, R. W.

    2013-11-01

    Balanced budgets for dissolved inorganic N (DIN) and particulate N (PN) were constructed for the Strait of Georgia (SoG), a semi-enclosed coastal sea off the west coast of British Columbia, Canada. The dominant control on the N budget is the advection of DIN into and out of the SoG via Haro Strait. The annual influx of DIN by advection from the Pacific Ocean is 29 990 (±19 500) Mmol yr-1. The DIN flux advected out of the SoG is 24 300 (±15 500) Mmol yr-1. Most of the DIN that enters the SoG (~ 23 400 Mmol yr-1) is converted to particulate N (PN) in situ by primary production. However, most of the PN produced by primary production is remineralized (~ 22 000 Mmol yr-1) back into DIN within the top 50 m. The PN budget for the SoG was further constrained by nitrogen isotope composition (δ15N) that indicated regional differences in the source of PN. The southern strait receives a much higher proportion of terrigenous PN, relative to marine PN, than does the northern strait. The difference is due to the influence of the Fraser River, which discharges 1950 Mmol yr-1 of PN and 1660 Mmol yr-1 of DIN into the southern strait. The overall anthropogenic contribution of PN and DIN to the SoG is minimal relative to natural sources (> 30 000 Mmol yr-1). It is unlikely that the strait will be affected by eutrophication in the near future, although anthropogenic N sources, such as wastewater outfalls, may have significant local effects.

  9. Disturbance-induced reduction of biomass carbon sinks of China’s forests in recent years

    NASA Astrophysics Data System (ADS)

    Zhang, Chunhua; Ju, Weimin; Chen, Jing M.; Wang, Xiqun; Yang, Lin; Zheng, Guang

    2015-11-01

    Forests play a critical role in mitigating climate change because of their high carbon storage and productivity. China has experienced a pronounced increase in forest area resulting from afforestation and reforestation activities since the 1970s. However, few comprehensive analyses have been made to assess the recent dynamics of biomass carbon sinks in China’s forests. This study refined biomass carbon sinks of China’s forests based on eight forest inventories from 1973 to 2013. These sinks increased from 25.0 to 166.5 Tg C yr-1 between 1973 and 2008, and then decreased to 130.9 Tg C yr-1 for the period of 2009-2013 because the increases in forest area and biomass carbon density became slower. About 7% and 93% of this sink reduction occurred in planted and natural forests. The carbon sinks for young, middle-aged and premature forests decreased by 27.3, 27.0, and 7.6 Tg C yr-1, respectively. 42% of this decrease was offset by mature and overmature forests. During 2009-2013, forest biomass carbon sinks decreased in all regions but the north and northwest regions. The drivers for changes of forest biomass sinks differ spatially. More intensive harvest of young and middle-aged forests and snow damage were the major drivers for the decreases of biomass carbon sinks in the east (8.0 Tg C yr-1) and south (19.8 Tg C yr-1) regions. The carbon sink reduction in the southwest region (16.7 Tg C yr-1) was mainly caused by increased timber harvesting and natural disturbances, such as droughts in Yunnan province, snow damage in Guizhou province and forest fires in Sichuan province. In the northeast region, the sink reduction occurred mainly in Heilongjiang province (7.9 Tg C yr-1) and was caused dominantly by the combined effects of diseases, windthrow and droughts. The carbon sink increase was primarily attributed to forest growth and decreased deforestation in the north (10.0 Tg C yr-1) and northwest (2.3 Tg C yr-1) regions.

  10. X-Ray Measured Dynamics of Tycho's Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Katsuda, Satoru; Petre, Robert; Hughes, John; Hwang, Una; Yamaguchi, Hiroya; Hayato, Asami; Mori, Koji; Tsunemi, Hiroshi

    2010-01-01

    We present X-ray proper-motion measurements of the forward shock and reverse-shocked ejecta in Tycho's supernova remnant, based on three sets of archival Chandra data taken in 2000, 2003, and 2007. We find that the proper motion of the edge of the remnant (i.e., the forward shock and protruding ejecta knots) varies from 0.''20 yr-1 (expansion index m = 0.33, where R = tm ) to 0.''40 yr-1 (m = 0.65) with azimuthal angle in 2000-2007 measurements, and 0.''14 yr-1 (m = 0.26) to 0.''40 yr-1 (m = 0.65) in 2003-2007 measurements. The azimuthal variation of the proper motion and the average expansion index of [approx]0.5 are consistent with those derived from radio observations. We also find proper motion and expansion index of the reverse-shocked ejecta to be 0.''21-0.''31 yr-1 and 0.43-0.64, respectively. From a comparison of the measured m-value with Type Ia supernova evolutionary models, we find a pre-shock ambient density around the remnant of [less, similar]0.2 cm-3.

  11. Seasonal Variation in the Inputs and Fate of Mercury in a Northern Hardwood Forest

    NASA Astrophysics Data System (ADS)

    Driscoll, C. T.; Wang, X.; Holsen, T.; Mao, H.

    2014-12-01

    Northern forest ecosystems are sensitive to atmospheric mercury deposition. In this study, we examined the fate of mercury inputs to the Huntington Wildlife Forest (HWF) of the Adirondack region of New York State, USA, by conducting a mercury mass budget over the annual cycle. Mercury exchange processes analyzed included wet deposition, dry deposition, foliar accumulation, throughfall, litterfall, soil evasion, and vertical and horizontal soil drainage loss. The mercury transport processes were quantified by integrating data collected from different sources over recent years (2004-2011). Dry mercury deposition (16.3 μg m-2 yr-1) was more important than wet mercury deposition (6.3 μg m-2 yr-1) at the HWF; most of the atmospheric mercury deposition (> 60%) was retained in the forest soils where litterfall (17.2 μg m-2 yr-1) was the major input pathway. Soil evasion (6.5 μg m-2 yr-1) was the most important mercury export mechanism, exceeding mercury fluxes in lateral and vertical drainage from soil (2.8 μg m-2 yr-1). Our analysis showed marked seasonal variation in the transfers of mercury largely mediated by annual canopy development of the forest ecosystem. The upland hardwood forest ecosystem was a net sink for atmospheric mercury deposition.

  12. Relevance of estuaries adjacent to megalopolis as modifiers of internal shelf areas

    NASA Astrophysics Data System (ADS)

    Wagener, Angela; Lazzzari, Leticia; Carreira, Renato; Farias, Cassia; Mauad, Cristiane

    2014-05-01

    Guanabara Bay located in the humid tropical region is a eutrophic estuarine system bordered by the second largest metropolitan area of Brazil. Human intervention resulted in water conditions ranging from complete anoxia in the polluted inner bay area to the adjacent, relatively pristine, open coastal area. In the present work the goals were to estimate nutrients and carbon fluxes between the bay and the adjacent coastal waters and to characterize by using stable isotopes, hydrocarbons and sterols the provenance of the exported/imported organic matter. Water samples were collected from three different depths over 25 hours cycles in the wet and dry seasons at a single station strategically positioned in the bay. Measurements included CTD, nutrients, chlorophylls, DOC, POC, PN, δ13C and δ15N, hydrocarbons and sterols in SPM. Most substances showed higher concentrations in ebb tide events and through statistical tools a significant difference between the campaigns was proved. The fluxes estimated on annual basis revealed the expressive exportation to the inner continental shelf of 1.27x104 Kmol DIN yr-1, 9.52x102 Kmol DIP yr-1, 2.65x104 tons DOC yr-1, 1.96x104 tons COP yr-1, 2.96x104 tons NP yr-1.

  13. An analysis of the carbon balance of the Arctic Basin

    SciTech Connect

    Mcguire, David; Hayes, Daniel J; Kicklighter, David W.; Manizza, Manfredi; Zhuang, Qianlai; Chen, Min; Follows, Michael J; Gurney, Kevin; Mcclelland, James W; Melillo, Jerry; Peterson, Bruce; Prinn, Ronald

    2010-01-01

    This study used several model-based tools to analyse the dynamics of the Arctic Basin between 1997 and 2006 as a linked system of land-ocean-atmosphere C exchange. The analysis estimates that terrestrial areas of the Arctic Basin lost 62.9 Tg C yr 1 and that the Arctic Ocean gained 94.1 Tg C yr 1. Arctic lands and oceans were a net CO2 sink of 108.9 Tg C yr 1, which is within the range of uncertainty in estimates from atmospheric inversions. Although both lands and oceans of the Arctic were estimated to be CO2 sinks, the land sink diminished in strength because of increased fire disturbance compared to previous decades, while the ocean sink increased in strength because of increased biological pump activity associated with reduced sea ice cover. Terrestrial areas of the Arctic were a net source of 41.5 Tg CH4 yr 1 that increased by 0.6 Tg CH4 yr 1 during the decade of analysis, a magnitude that is comparable with an atmospheric inversion of CH4. Because the radiative forcing of the estimated CH4 emissions is much greater than the CO2 sink, the analysis suggests that the Arctic Basin is a substantial net source of green house gas forcing to the climate system.

  14. Rising critical emission of air pollutants from renewable biomass based cogeneration from the sugar industry in India

    NASA Astrophysics Data System (ADS)

    Sahu, S. K.; Ohara, T.; Beig, G.; Kurokawa, J.; Nagashima, T.

    2015-09-01

    In the recent past, the emerging India economy is highly dependent on conventional as well as renewable energy to deal with energy security. Keeping the potential of biomass and its plentiful availability, the Indian government has been encouraging various industrial sectors to generate their own energy from it. The Indian sugar industry has adopted and made impressive growth in bagasse (a renewable biomass, i.e. left after sugercane is crushed) based cogeneration power to fulfil their energy need, as well as to export a big chunk of energy to grid power. Like fossil fuel, bagasse combustion also generates various critical pollutants. This article provides the first ever estimation, current status and overview of magnitude of air pollutant emissions from rapidly growing bagasse based cogeneration technology in Indian sugar mills. The estimated emission from the world’s second largest sugar industry in India for particulate matter, NOX, SO2, CO and CO2 is estimated to be 444 ± 225 Gg yr-1, 188 ± 95 Gg yr-1, 43 ± 22 Gg yr-1, 463 ± 240 Gg yr-1 and 47.4 ± 9 Tg yr-1, respectively in 2014. The studies also analyze and identify potential hot spot regions across the country and explore the possible further potential growth for this sector. This first ever estimation not only improves the existing national emission inventory, but is also useful in chemical transport modeling studies, as well as for policy makers.

  15. An analysis of the carbon balance of the Arctic Basin from 1997 to 2006

    USGS Publications Warehouse

    McGuire, A.D.; Hayes, D.J.; Kicklighter, D.W.; Manizza, M.; Zhuang, Q.; Chen, M.; Follows, M.J.; Gurney, K.R.; McClelland, J.W.; Melillo, J.M.; Peterson, B.J.; Prinn, R.G.

    2010-01-01

    This study used several model-based tools to analyse the dynamics of the Arctic Basin between 1997 and 2006 as a linked system of land-ocean-atmosphere C exchange. The analysis estimates that terrestrial areas of the Arctic Basin lost 62.9 Tg C yr-1 and that the Arctic Ocean gained 94.1 Tg C yr-1. Arctic lands and oceans were a net CO2 sink of 108.9 Tg C yr-1, which is within the range of uncertainty in estimates from atmospheric inversions. Although both lands and oceans of the Arctic were estimated to be CO2 sinks, the land sink diminished in strength because of increased fire disturbance compared to previous decades, while the ocean sink increased in strength because of increased biological pump activity associated with reduced sea ice cover. Terrestrial areas of the Arctic were a net source of 41.5 Tg CH4 yr-1 that increased by 0.6 Tg CH4 yr-1 during the decade of analysis, a magnitude that is comparable with an atmospheric inversion of CH4. Because the radiative forcing of the estimated CH4 emissions is much greater than the CO2 sink, the analysis suggests that the Arctic Basin is a substantial net source of green house gas forcing to the climate system.

  16. Deformation across the Pacific-North America plate boundary near San Francisco, California

    USGS Publications Warehouse

    Prescott, W.H.; Savage, J.C.; Svarc, J.L.; Manaker, D.

    2001-01-01

    We have detected a narrow zone of compression between the Coast Ranges and the Great Valley, and we have estimated slip rates for the San Andreas, Rodgers Creek, and Green Valley faults just north of San Francisco. These results are based on an analysis of campaign and continuous Global Positioning System (GPS) data collected between 1992 and 2000 in central California. The zone of compression between the Coast Ranges and the Great Valley is 25 km wide. The observations clearly show 3.8??1.5 mm yr-1 of shortening over this narrow zone. The strike slip components are best fit by a model with 20.8??1.9 mm yr-1 slip on the San Andreas fault, 10.3??2.6 mm yr-1 on the Rodgers Creek fault, and 8.1??2.1 mm yr-1 on the Green Valley fault. The Pacific-Sierra Nevada-Great Valley motion totals 39.2??3.8 mm yr-1 across a zone that is 120 km wide (at the latitude of San Francisco). Standard deviations are one ??. The geodetic results suggest a higher than geologic rate for the Green Valley fault. The geodetic results also suggest an inconsistency between geologic estimates of the San Andreas rate and seismologic estimates of the depth of locking on the San Andreas fault. The only convergence observed is in the narrow zone along the border between the Great Valley and the Coast Ranges.

  17. Spatiotemporal pattern of soil respiration of terrestrial ecosystems in China: the development of a geostatistical model and its simulation.

    PubMed

    Yu, Guirui; Zheng, Zemei; Wang, Qiufeng; Fu, Yuling; Zhuang, Jie; Sun, Xiaomin; Wang, Yuesi

    2010-08-15

    Quantification of the spatiotemporal pattern of soil respiration (R(s)) at the regional scale can provide a theoretical basis and fundamental data for accurate evaluation of the global carbon budget. This study summarizes the R(s) data measured in China from 1995 to 2004. Based on the data, a new region-scale geostatistical model of soil respiration (GSMSR) was developed by modifying a global scale statistical model. The GSMSR model, which is driven by monthly air temperature, monthly precipitation, and soil organic carbon (SOC) density, can capture 64% of the spatiotemporal variability of soil R(s). We evaluated the spatiotemporal pattern of R(s) in China using the GSMSR model. The estimated results demonstrate that the annual R(s) in China ranged from 3.77 to 4.00 Pg C yr(-1) between 1995 and 2004, with an average value of 3.84 +/- 0.07 Pg C yr(-1), contributing 3.92%-4.87% to the global soil CO(2) emission. Annual R(s) rate of evergreen broadleaved forest ecosystem was 698 +/- 11 g C m(-2) yr(-1), significantly higher than that of grassland (439 +/- 7 g C m(-2) yr(-1)) and cropland (555 +/- 12 g C m(-2) yr(-1)). The contributions of grassland, cropland, and forestland ecosystems to the total R(s) in China were 48.38 +/- 0.35%, 22.19 +/- 0.18%, and 20.84 +/- 0.13%, respectively. PMID:20704202

  18. Foliage/atmosphere exchange of mercury in a subtropical coniferous forest in south China

    NASA Astrophysics Data System (ADS)

    Luo, Yao; Duan, Lei; Driscoll, Charles T.; Xu, Guangyi; Shao, Mengshu; Taylor, Mariah; Wang, Shuxiao; Hao, Jiming

    2016-07-01

    Foliage/atmosphere exchange is an important pathway of deposition and loss in the biogeochemical mercury (Hg) cycle of terrestrial ecosystems. The foliage/atmosphere fluxes of Hg0 were observed over four seasons in a Masson pine (Pinus massoniana) forest in south China. Hg0 exchange showed a bidirectional process but without clear compensation point. Hg0 emissions peaked midday in all four seasons, probably associated with Hg photoreduction on needle surface. Peaks in Hg0 adsorption/deposition often occurred in the morning, especially in spring and autumn. Although current-year needles accumulated Hg at a rate of 19.4 µg m-2 yr-1, they were a net Hg0 source of 1.7 µg m-2 yr-1 to the atmosphere as their release of Hg exceeded inputs. In addition, previous-year needles emitted Hg0 at an average rate of 9.2 µg m-2 yr-1. Based on the mass balance of Hg in the forest canopy, the dry deposition of Hg was estimated 52.5 µg m-2 yr-1, much higher than the wet deposition (to 14.4 µg m-2 yr-1). Although Hg in the atmosphere is considered the main source of Hg in folia, soil water may contribute to Hg0 emission by plant transpiration. These processes should be further studied in the future.

  19. On VI Observations of Galaxy Clusters: Evidence for Modest Cooling Flows

    NASA Astrophysics Data System (ADS)

    Bregman, Joel N.; Fabian, A. C.; Miller, Eric D.; Irwin, Jimmy A.

    2006-05-01

    A prediction of the galaxy-cluster cooling flow model is that as gas cools from the ambient cluster temperature, emission lines are produced in gas at subsequently decreasing temperatures. Gas passing through 105.5 K emits in the lines of O VI λλ1032, 1035, and here we report a FUSE study of these lines in three cooling flow clusters, Abell 426, Abell 1795, and AWM 7. No emission was detected from AWM 7, but O VI is detected from the centers of Abell 426 and Abell 1795, and possibly to the south of the center in Abell 1795, where X-ray and optical emission line filaments lie. In Abell 426 these line luminosities imply a cooling rate of 32+/-6 Msolar yr-1 within the central r=6.2 kpc region, while for Abell 1795 the central cooling rate is 26+/-7 Msolar yr-1 (within r=22 kpc), and about 42+/-9 Msolar yr-1 including the southern pointing. Including other studies, three of six clusters have O VI emission, and they also have star formation as well as emission lines from 104 K gas. These observations are generally consistent with the cooling flow model, but at a rate closer to 30 Msolar yr-1 than to the originally suggested values of 102-10 3 Msolar yr-1.

  20. Molecular clouds and star formation : a multiwavelength study of Perseus, Serpens, and Ophiuchus

    NASA Astrophysics Data System (ADS)

    Enoch, Melissa Lanae

    NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.In this thesis I utilize large-scale millimeter and mid- to far-infrared surveys to address a number of outstanding questions regarding the formation of low mass stars in molecular clouds. Continuum [lambda] = 1.1 mm maps completed with Bolocam at a resolution of 31" cover the largest areas observed to date at millimeter or submillimeter wavelengths in three molecular clouds: 7.5 deg(2) in Perseus (140 pc(2) at the adopted distance of d = 250 pc), 10.8 deg(2) (50 pc(2) at d = 125 pc) in Ophiuchus, and 1.5 deg(2) (30 pc(2) at d = 125 pc) in Serpens. These surveys are sensitive to dense substructures with mean density n [...] 2 - 3 x 10(4) cm(-3). A total of 122 cores are detected in Perseus, 44 in Ophiuchus, and 35 in Serpens above mass detection limits of 0.1 - 0.2 Msun. Combining with Spitzer mid- and far-infrared maps from the c2d Legacy program provides wavelength coverage from [lambda] = 1.25-1100 micron, and enables the assembly of an unbiased, complete sample of the youngest star forming objects in three environments. This sample includes 108 prestellar cores, 43 Class 0 sources and 94 Class I sources.The approximately equal number of starless cores and embedded protostars in each cloud implies a starless core lifetime of 2 - 4 x 10(5) yr, only a few free-fall timescales. This timescale, considerably shorter than the timescale predicted by the classic scenario of magnetic field support in which core evolution is moderated by ambipolar diffusion, suggests that turbulence is the dominant process controlling the formation and evolution of dense cores. However, dense cores in all three clouds are found only at high cloud column densities, where [...] 7 mag, and the fraction of cloud mass in these cores is less than 10%, indicating that magnetic fields must play some role as well. Measured angular deconvolved sizes of the majority of starless cores are

  1. XMM-Newton Detection of Hard X-Ray Emission in the Nitrogen-Type Wolf-Rayet Star WR 110

    NASA Astrophysics Data System (ADS)

    Skinner, Stephen L.; Zhekov, Svetozar A.; Güdel, Manuel; Schmutz, Werner

    2002-06-01

    We have used the excellent sensitivity of XMM-Newton to obtain the first high-quality X-ray spectrum of a Wolf-Rayet (W-R) star that is not known to be a member of a binary system. Our target, the nitrogen-type star WR 110 (HD 165688), was also observed and detected with the Very Large Array at four different frequencies. The radio flux density increases with frequency according to a power law Sν~ν+0.64+/-0.10, in very good agreement with the behavior expected for free-free wind emission. The radio data give an ionized mass-loss rate M=4.9×10-5 Msolar yr-1 for an assumed spherical constant-velocity wind. The undispersed CCD X-ray spectra reveal strong emission lines from He-like ions of Mg, Si, and S. The emission measure distribution shows a dominant contribution from cool plasma with a characteristic temperature kTcool~0.5 keV (~6 MK). Little or no excess absorption of this cool component above the value expected from the visual extinction is present. We conclude that the bulk of the cool plasma detected by XMM-Newton lies at hundreds of stellar radii or more if the wind is approximately spherical and homogeneous, but it could lie closer to the star if the wind is clumped. If the cool plasma is due to instability-driven wind shocks, then typical shock velocities are vs~340-550 km s-1 and the average filling factor of X-ray-emitting gas in the wind is no larger than f~10-6. A surprising result is the unambiguous detection of a hard X-ray component that is clearly seen in the hard-band images and the spectra. This hard component accounts for about half of the observed flux and can be acceptably fitted by a hot, optically thin thermal plasma or a power-law model. If the emission is thermal, then a temperature kThot>=3 keV is derived. Such high temperatures are not predicted by current instability-driven wind shock models, and a different mechanism is thus required to explain the hard X-rays. We examine several possible mechanisms and show that the hard emission

  2. Emission Lines from the Gas Disk around TW Hydra and the Origin of the Inner Hole

    NASA Astrophysics Data System (ADS)

    Gorti, U.; Hollenbach, D.; Najita, J.; Pascucci, I.

    2011-07-01

    We compare line emission calculated from theoretical disk models with optical to submillimeter wavelength observational data of the gas disk surrounding TW Hya and infer the spatial distribution of mass in the gas disk. The model disk that best matches observations has a gas mass ranging from ~10-4 to 10-5 M sun for 0.06 AU < r < 3.5 AU and ~0.06 M sun for 3.5 AU < r < 200 AU. We find that the inner dust hole (r < 3.5 AU) in the disk must be depleted of gas by ~1-2 orders of magnitude compared with the extrapolated surface density distribution of the outer disk. Grain growth alone is therefore not a viable explanation for the dust hole. CO vibrational emission arises within r ~ 0.5 AU from thermal excitation of gas. [O I] 6300 Å and 5577 Å forbidden lines and OH mid-infrared emission are mainly due to prompt emission following UV photodissociation of OH and water at r <~ 0.1 AU and at r ~ 4 AU. [Ne II] emission is consistent with an origin in X-ray heated neutral gas at r <~ 10 AU, and may not require the presence of a significant extreme-ultraviolet (hν > 13.6 eV) flux from TW Hya. H2 pure rotational line emission comes primarily from r ~ 1 to 30 AU. [O I] 63 μm, HCO+, and CO pure rotational lines all arise from the outer disk at r ~ 30-120 AU. We discuss planet formation and photoevaporation as causes for the decrease in surface density of gas and dust inside 4 AU. If a planet is present, our results suggest a planet mass ~4-7 MJ situated at ~3 AU. Using our photoevaporation models and the best surface density profile match to observations, we estimate a current photoevaporative mass loss rate of 4 × 10-9 M sun yr-1 and a remaining disk lifetime of ~5 million years.

  3. Reprocessing in Luminous Disks

    NASA Astrophysics Data System (ADS)

    Bell, K. R.

    1999-11-01

    We develop and investigate a procedure that accounts for disk reprocessing of photons that originate in the disk itself. Surface temperatures and simple, blackbody spectral energy distributions (SEDs) of protostellar disks are calculated. In disks that flare with radius, reprocessing of stellar photons results in temperature profiles that are not power-law at all radii but are consistently shallower than r-3/4. Including the disk as a radiation source (as in the case of active accretion) along with the stellar source further flattens the temperature profile. Disks that flare strongly near the star and then smoothly curve over and become shadowed at some distance (``decreasing curvature'' disks) exhibit nearly power-law temperature profiles that result in power-law infrared SEDs with slopes in agreement with typical observations of young stellar objects. Disk models in which the photospheric thickness is controlled by the local opacity and in which the temperature decreases with radius naturally have this shape. Uniformly flaring models do not match observations as well; progressively stronger reprocessing at larger radii leads to SEDs that flatten toward the infrared or even have a second peak at the wavelength corresponding (through the Wien law) to the temperature of the outer edge of the disk. In FU Orionis outbursting systems, the dominant source of energy is the inner disk. Reprocessing throughout the disk depends sensitively on the inner disk shape and emitted temperature profile. We show that the thermal instability outburst models of Bell & Lin reproduce trends in the observed SEDs of FU Ori systems with T~r-3/4 in the inner disk (r<~0.25 AU corresponding to λ<~10 μm) and T~r-1/2 in the outer disk. Surface irradiation during outburst and quiescence is compared in the region of planet formation (1-10 AU). The contrast between the two phases is diminished by the importance of the reprocessing of photons from the relatively high mass flux, outer disk (Ṁ=10-5

  4. The global atmospheric environment for the next generation.

    PubMed

    Dentener, F; Stevenson, D; Ellingsen, K; Van Noije, T; Schultz, M; Amann, M; Atherton, C; Bell, N; Bergmann, D; Bey, I; Bouwman, L; Butler, T; Cofala, J; Collins, B; Drevet, J; Doherty, R; Eickhout, B; Eskes, H; Fiore, A; Gauss, M; Hauglustaine, D; Horowitz, L; Isaksen, I S A; Josse, B; Lawrence, M; Krol, M; Lamarque, J F; Montanaro, V; Müller, J F; Peuch, V H; Pitari, G; Pyle, J; Rast, S; Rodriguez, I; Sanderson, M; Savage, N H; Shindell, D; Strahan, S; Szopa, S; Sudo, K; Van Dingenen, R; Wild, O; Zeng, G

    2006-06-01

    Air quality, ecosystem exposure to nitrogen deposition, and climate change are intimately coupled problems: we assess changes in the global atmospheric environment between 2000 and 2030 using 26 state-of-the-art global atmospheric chemistry models and three different emissions scenarios. The first (CLE) scenario reflects implementation of current air quality legislation around the world, while the second (MFR) represents a more optimistic case in which all currently feasible technologies are applied to achieve maximum emission reductions. We contrast these scenarios with the more pessimistic IPCC SRES A2 scenario. Ensemble simulations for the year 2000 are consistent among models and show a reasonable agreement with surface ozone, wet deposition, and NO2 satellite observations. Large parts of the world are currently exposed to high ozone concentrations and high deposition of nitrogen to ecosystems. By 2030, global surface ozone is calculated to increase globally by 1.5 +/- 1.2 ppb (CLE) and 4.3 +/- 2.2 ppb (A2), using the ensemble mean model results and associated +/-1 sigma standard deviations. Only the progressive MFR scenario will reduce ozone, by -2.3 +/- 1.1 ppb. Climate change is expected to modify surface ozone by -0.8 +/- 0.6 ppb, with larger decreases over sea than over land. Radiative forcing by ozone increases by 63 +/- 15 and 155 +/- 37 mW m(-2) for CLE and A2, respectively, and decreases by -45 +/- 15 mW m(-2) for MFR. We compute that at present 10.1% of the global natural terrestrial ecosystems are exposed to nitrogen deposition above a critical load of 1 g N m(-2) yr(-1). These percentages increase by 2030 to 15.8% (CLE), 10.5% (MFR), and 25% (A2). This study shows the importance of enforcing current worldwide air quality legislation and the major benefits of going further. Nonattainment of these air quality policy objectives, such as expressed by the SRES-A2 scenario, would further degrade the global atmospheric environment. PMID:16786698

  5. The effect of sudden ice sheet melt on ocean circulation and surface climate 14-16 ka

    NASA Astrophysics Data System (ADS)

    Ivanovic, Ruza; Gregoire, Lauren; Wickert, Andrew; Valdes, Paul

    2016-04-01

    Collapse of ice sheets can cause significant sea-level rise and widespread climate change. Around 14.6 thousand years ago, global sea level rose by ˜15 m in less than 350 years[1] during an event known as Meltwater Pulse 1a. Modelling work[2,3] has suggested that approximately half of this ˜50 mm yr-1 sea level rise came from a North American ice Saddle Collapse that drained into the Arctic and Atlantic Oceans. However, dating uncertainties make it difficult to determine the sequence of events and their drivers, leaving many fundamental questions. For example, did the abrupt ice melting and subsequent ocean freshening have any detectable climatic impact? Was melting from the Northern American ice sheets responsible for the Older-Dryas[4] or other cooling events? And how were all these signals linked to changes in Atlantic Ocean overturning circulation[e.g.5]? To address these questions, we examined the effect of the North American ice Saddle Collapse using a newly developed high resolution network drainage model coupled to an atmosphere-ocean-vegetation General Circulation Model. Here, we present the first quantitative routing estimates of the consequent meltwater discharge and its impact on climate. The results show that approximately 50% of the Saddle Collapse meltwater pulse was routed down the Mackenzie River into the Arctic Ocean, and around half was discharged directly into the Atlantic via the St. Lawrence River. This meltwater flux, equivalent to a total of 7 m of sea-level rise, caused a strong weakening of Atlantic Meridional Overturning Circulation (AMOC) and widespread Northern Hemisphere cooling. The greatest cooling is in the Arctic, but there is also significant warming over North America. We find that AMOC (and climate) is most sensitive to meltwater discharged to the Arctic Ocean. [1] Deschamps et al. (2012) Nature 483, 559-564. [2] Gregoire et al. (2012) Nature 487, 219-222. [3] Gomez et al. (2015) GRL 42(10), 3954-3962. [4] Menviel et al. (2010

  6. Femoral lipectomy increases postprandial lipemia in women.

    PubMed

    Hernandez, Teri L; Bessesen, Daniel H; Cox-York, Kimberly A; Erickson, Christopher B; Law, Christopher K; Anderson, Molly K; Wang, Hong; Jackman, Matthew R; Van Pelt, Rachael E

    2015-07-01

    Femoral subcutaneous adipose tissue (SAT) appears to be cardioprotective compared with abdominal SAT, possibly through better triglyceride (TG) sequestration. We hypothesized that removal of femoral SAT would increase postprandial TG through a reduction in dietary fatty acid (FA) storage. Normal-weight (means ± SD; BMI 23.9 ± 2.6 kg/m(2)) women (n = 29; age 45 ± 6 yr) were randomized to femoral lipectomy (LIPO) or control (CON) and followed for 1 yr. Regional adiposity was measured by DEXA and CT. A liquid meal labeled with [(14)C]oleic acid was used to trace the appearance of dietary FA in plasma (6-h postprandial TG), breath (24-h oxidation), and SAT (24-h [(14)C]TG storage). Fasting LPL activity was measured in abdominal and femoral SAT. DEXA leg fat mass was reduced after LIPO vs. CON (Δ-1.4 ± 0.7 vs. 0.1 ± 0.5 kg, P < 0.001) and remained reduced at 1 yr (-1.1 ± 1.4 vs. -0.2 ± 0.5 kg, P < 0.05), as did CT thigh subcutaneous fat area (-39.6 ± 36.6 vs. 4.7 ± 14.6 cm(2), P < 0.05); DEXA trunk fat mass and CT visceral fat area were unchanged. Postprandial TG increased (5.9 ± 7.7 vs. -0.6 ± 5.3 × 10(3) mg/dl, P < 0.05) and femoral SAT LPL activity decreased (-21.9 ± 22.3 vs. 10.5 ± 26.5 nmol·min(-1)·g(-1), P < 0.05) 1 yr following LIPO vs. CON. There were no group differences in (14)C-labeled TG appearing in abdominal and femoral SAT or elsewhere. In conclusion, femoral fat remained reduced 1 yr following lipectomy and was accompanied by increased postprandial TG and reduced femoral SAT LPL activity. There were no changes in storage of meal-derived FA or visceral fat. Our data support a protective role for femoral adiposity on circulating TG independent of dietary FA storage and visceral adiposity.

  7. Early-time spectra of supernovae and their precursor winds. The luminous blue variable/yellow hypergiant progenitor of SN 2013cu

    NASA Astrophysics Data System (ADS)

    Groh, Jose H.

    2014-12-01

    We present the first quantitative spectroscopic modeling of an early-time supernova (SN) that interacts with its progenitor wind. Using the radiative transfer code CMFGEN, we investigate the recently reported 15.5 h post-explosion spectrum of the type IIb SN 2013cu. We are able to directly measure the chemical abundances of a SN progenitor and find a relatively H-rich wind, with H and He abundances (by mass) of X = 0.46 ± 0.2 and Y = 0.52 ± 0.2, respectively. The wind is enhanced in N and depleted in C relative to solar values (mass fractions of 8.2 × 10-3 and 1.0 × 10-5, respectively). We obtain that a slow, dense wind or circumstellar medium surrounds the precursor at the pre-SN stage, with a wind terminal velocity vwind ≲ 100 km s-1 and mass-loss rate of Ṁ ≃ 3 × 10-3 (vwind/ 100 km s-1) M⊙ yr-1. These values are lower than previous analytical estimates, although Ṁ/υ∞ is consistent with previous work. We also compute a CMFGEN model to constrain the progenitor spectral type; the high Ṁ and low vwind imply that the star had an effective temperature of ≃ 8000 K immediately before the SN explosion. Our models suggest that the progenitor was either an unstable luminous blue variable or a yellow hypergiant undergoing an eruptive phase, and rule out a Wolf-Rayet star. We classify the post-explosion spectra at 15.5 h as XWN5(h) and advocate for the use of the prefix "X" (eXplosion) to avoid confusion between post-explosion, non-stellar spectra, and those of massive stars. We show that the XWN spectrum results from the ionization of the progenitor wind after the SN, and that the progenitor spectral type is significantly different from the early post-explosion spectral type owing to the huge differences in the ionization structure before and after the SN event. We find the following temporal evolution: LBV/YHG → XWN5(h) → SN IIb. Future early-time spectroscopy in the UV will further constrain the properties of SN precursors, such as their

  8. Studies based on global subsurface radar sounding of the Moon by SELENE (Kaguya) Lunar Radar Sounder (LRS): A summary

    NASA Astrophysics Data System (ADS)

    Kumamoto, A.; Yamaguchi, Y.; Yamaji, A.; Kobayashi, T.; Oshigami, S.; Ishiyama, K.; Nakamura, N.; Goto, Y.

    2015-12-01

    The Lunar Radar Sounder (LRS) onboard the SELENE (Kaguya) spacecraft has successfully performed radar sounder observations of the lunar subsurface structures and passive observations of natural radio and plasma waves from the lunar orbit. After the transfer of the spacecraft into the final lunar orbit and antenna deployment, the operation of LRS started on October 29, 2007. Through the operation until June 10, 2009, 130 million pulses worth of radar sounder data have been obtained [Ono et al., 2010]. Based on the datasets of the first lunar global subsurface radar sounding, Ono et al. [2009] revealed that there are distinct reflectors at a depth of several hundred meters in the nearside maria, which are inferred to be buried regolith layers covered by a basalt layer with a thickness of several hundred meters. Based on the further survey, Pommerol et al. [2010] pointed out the negative correlation of clear subsurface echoes with the maps of ilmenite, and suggested that dense ilmenite attenuates the radar pulse in the basaltic mare lava, and cause the absence of the clear subsurface echoes. That also suggests there are undetected subsurface reflectors especially below the young lava flow units with high ilmenite abundance. Kobayashi et al. [2012] applied synthetic aperture radar (SAR) processing to SELENE LRS data in order to obtain distinct radargram. Taking advantage of analyzing waveform data sent via high data rate telemetry from the Moon, we can perform advanced data analyses on the ground. We started providing the both SAR processed and waveform datasets via SELENE Data Archive (http://l2db.selene.darts.isas.jaxa.jp/index.html.en) since 2015. Oshigami et al. [2014] estimated volumes of basalt units in the ages of 2.7 Ga to 3.8 Ga in the nearside maria. The volume was derived from the depth of subsurface reflectors measured by LRS. The volumes of the geologic units were 103 to 104 km3. The average eruption rates were 10-5 to 10-3 km3 yr-1. The estimated volumes

  9. The Tista Megafan, a ~50 kyr Record of Drainage Development, Erosion and Weathering in the Sikkim Himalayas (Eastern India)

    NASA Astrophysics Data System (ADS)

    Abrahami, R.; Huyghe, P.; Van Der Beek, P.; Lowick, S.; Garzanti, E.; Revillon, S.; Carcaillet, J.; Chakraborty, T.

    2015-12-01

    The Tista River, a major tributary of the Brahmaputra drainage system (Eastern Himalaya) has built a fluvial deposit which extents over 16500 km2. The Tista megafan stands out because of (1) its disproportionate size compared to that of the upstream Tista River catchment (8000 km2), and (2) it has been incised about 50m by the river at the topographic front of the mountain range. Neither the timing of deposition/incision of the megafan sediments, and their potential tectonic or climatic controls have yet been investigated. We use both IRSL and 10Be cosmogenic data to respectively constrain the date of deposition and abandonment of the different lobes of the megafan. We suggest that two distal lobes developed successively downstream from a common proximal lobe. Deposition took place since ~50 ka and incision began at 4.0 +0.6/-0.4 ka at an average rate of 10.5 +0.6/-1.8 mm yr-1. In addition, petrology, isotope geochemistry (ɛNd, 87Sr/86Sr) and chemical composition performed on modern river sands and late-Quaternary megafan sediments allows characterizing (1) provenance variations through time of megafan deposits and their implication for drainage development (2) the weathering history of Sikkim recorded by the megafan deposits. Results show that the Tista fan deposits are mainly sourced from the High Himalayan Crystalline domain and the Tethyan Sedimentary Series, (consistent with high erosion rates identified in north Sikkim at millennial timescale). Variations in provenance and weathering through time recorded by the Tista megafan deposits can be linked to climatic variations with strong monsoonal precipitations penetrating further northward into the southern Tibetan plateau. Tectonic processes seem to play a minor role. Otherwise, we propose as a first hypothesis that the Kosi River has recently (at ~4 ka) captured the upper part of the Tista catchment. That could explain the particular isotopic signature of the Tista megafan deposits, its recent incision, its

  10. Leo P: An Unquenched Very Low-mass Galaxy

    NASA Astrophysics Data System (ADS)

    McQuinn, Kristen B. W.; Skillman, Evan D.; Dolphin, Andrew; Cannon, John M.; Salzer, John J.; Rhode, Katherine L.; Adams, Elizabeth A. K.; Berg, Danielle; Giovanelli, Riccardo; Girardi, Léo; Haynes, Martha P.

    2015-10-01

    Leo P is a low-luminosity dwarf galaxy discovered through the blind H i Arecibo Legacy Fast ALFA survey. The H i and follow-up optical observations have shown that Leo P is a gas-rich dwarf galaxy with active star formation, an underlying older population, and an extremely low oxygen abundance. We have obtained optical imaging with the Hubble Space Telescope to two magnitudes below the red clump in order to study the evolution of Leo P. We refine the distance measurement to Leo P to be 1.62 ± 0.15 Mpc, based on the luminosity of the horizontal branch stars and 10 newly identified RR Lyrae candidates. This places the galaxy at the edge of the Local Group, ˜0.4 Mpc from Sextans B, the nearest galaxy in the NGC 3109 association of dwarf galaxies of which Leo P is clearly a member. The star responsible for ionizing the H ii region is most likely an O7V or O8V spectral type, with a stellar mass ≳25 M⊙. The presence of this star provides observational evidence that massive stars at the upper end of the initial mass function are capable of being formed at star formation rates as low as ˜10-5 M⊙ yr-1. The best-fitting star formation history (SFH) derived from the resolved stellar populations of Leo P using the latest PARSEC models shows a relatively constant star formation rate over the lifetime of the galaxy. The modeled luminosity characteristics of Leo P at early times are consistent with low-luminosity dSph Milky Way satellites, suggesting that Leo P is what a low-mass dSph would look like if it evolved in isolation and retained its gas. Despite the very low mass of Leo P, the imprint of reionization on its SFH is subtle at best, and consistent with being totally negligible. The isolation of Leo P, and the total quenching of star formation of Milky Way satellites of similar mass, implies that the local environment dominates the quenching of the Milky Way satellites. Based on observations made with the NASA/ESA Hubble Space Telescope (HST), obtained from the

  11. The Martian hydrologic system: Multiple recharge centers at large volcanic provinces and the contribution of snowmelt to outflow channel activity

    NASA Astrophysics Data System (ADS)

    Russell, Patrick S.; Head, James W.

    2007-02-01

    Global recharge of the martian hydrologic system has traditionally been viewed as occurring through basal melting of the south polar cap. We conclude that regional recharge of a groundwater system at the large volcanic provinces, Elysium and Tharsis, is also very plausible and has several advantages over a south polar recharge source in providing a more direct, efficient supply of water to the outflow channel source regions surrounding these areas. This recharge scenario is proposed to have operated concurrently with and within the context of a global cryosphere-hydrosphere system of the subsurface characteristic of post-Noachian periods. To complement existing groundwater flow modeling studies, we examine geologic evidence and possible mechanisms for accumulation of water at high elevations on the volcanic rises, such as melting snow, infiltration, and increased effective permeability of the subsurface between the recharge zone and outflow source. Evidence for the presence of large Amazonian-aged cold-based piedmont glaciers on the Tharsis Montes has been well documented. Climate modeling predicts snow accumulation on high volcanic rises at obliquities thought to be typical over much of martian history. Thermal gradients causing basal melting of snowpack over 1 km thick could provide several kg m -2 yr -1 of water, charging a volume equivalent to the pore space in a square meter column of subsurface in less than 1.5×10 5 yr. In order to account for estimated outflow channel volumes, the subsurface volume above the elevation of the outflow channels must be charged several times over the area of Tharsis. Complete aquifer recharge can be accomplished in ˜0.3-2 My through the snowpack melting mechanism at Tharsis and in ˜5×10 4 years for channel requirements at Elysium. Abundant radial dikes emanating from large martian volcanic rises can crack and/or melt the cryosphere, initiating water outflow and creating anisotropies that can channel subsurface water from a

  12. Timing of detachment faulting in the Bullfrog Hills and Bare Mountain area, southwest Nevada: Inferences from40Ar/39Ar, K-Ar, U-Pb, and fission track thermochronology

    USGS Publications Warehouse

    Hoisch, T.D.; Heizler, M.T.; Zartman, R.E.

    1997-01-01

    Crustal extension in the Bullfrog Hills and Bare Mountain area of southwest Nevada is associated with movement along a regional detachment fault. Normal faulting in the upper plate and rapid cooling (denudation) of the lower plate were coeval with Miocene silicic volcanism and with west-northwest transport along the detachment fault. A west-northwest progression of tilting along upper plate normal faults is indicated by ages of the volcanic rocks in relation to angular unconformities. Near the breakaway, tilting in the upper plate occurred between 12.7 and 11.6 Ma, continued less strongly past 10.7 Ma, and was over by 8.2 Ma. Ten to 20 km west of the breakaway, tilting occurred between 10.7 and 10.33 Ma, continued less strongly after 10.33 Ma, and was over by 8.1 Ma. The cooling histories of the lower plate metamorphic rocks were determined by thermochronologic dating methods: K-Ar and 40Ar/39Ar on muscovite, biotite, and hornblende, 40Ar/39Ar on K-feldspar, U-Pb on apatite, zircon, and sphene, and fission track on apatite, zircon, and sphene. Lower plate rocks 10 km west of the breakaway cooled slowly from Early Cretaceous lower-amphibolite facies conditions through 350??50?? to 300??50??C between 57 and 38 Ma, then cooled rapidly from 205??50?? to 120??50??C between 12.6??1.6 and 11.1??1.9 Ma. Lower plate rocks 20 km west of the breakaway cooled slowly from Early Cretaceous upper-amphibolite facies conditions through 500??50??C at 78-67 Ma, passed through 350??50?? to 300??50??C between 16.3??0.4 and 10.5??0.3 Ma, then cooled rapidly from 285??50?? to 120??50??C between 10.2 and 8.6 Ma. Upper plate tilting and rapid cooling (denudation) of the lower plate occurred simultaneously in the respective areas. The early slow-cooling part of the lower plate thermal histories was probably related to erosion at the Earth's surface, which stripped off about 9 km of material in 50 to 100 m.y. The results indicate an initial fault dip ???30?? and a 12 mm yr-1 west

  13. Global collapse of the DR21 filament

    NASA Astrophysics Data System (ADS)

    Schneider, N.; Csengeri, T.; Bontemps, S.; Motte, F.; Simon, R.; Hennebelle, P.; Federrath, C.; Klessen, R.

    2011-05-01

    The formation of massive stars is a highly complex process in which it is unclear whether the star-forming gas is in global gravitational collapse or an equilibrium state supported by turbulence and/or magnetic fields. By studying the most massive and dense star-forming clump in the Galaxy at a distance of less than 3 kpc, i.e. the filament containing DR21 and DR21(OH), we obtained observational evidence to help us to discriminate between these two views. For that, we used molecular line data from our 13CO 1→0, CS 2→1, and N_2H^+ 1→0 survey of the Cygnus X region (FCRAO) and high-angular resolution observations in isotopomeric lines of CO, CS, HCO^+, N_2H^+, and H_2CO, obtained with the IRAM 30m telescope. The observations reveal a complex velocity field and velocity dispersion in which regions of the highest column-density, i.e. dense cores, have a lower velocity dispersion than the surrounding gas and velocity gradients that are not (only) due to rotation. Infall signatures in optically thick line profiles of HCO^+ and 12CO are observed along and across the whole DR21 filament. By modelling the observed spectra, we obtain a typical infall speed of ˜0.6 km s-1 and mass accretion rates of the order of a few 10-3 M_⊙ yr-1 for the two main clumps constituting the filament. These massive clumps (4900 and 3300 M_⊙ at densities of around 10^5 cm-3 within 1 pc diameter) are both gravitationally contracting (with free-fall times much shorter than sound crossing times and low virial parameter α). The more massive of the clumps, DR21(OH), is connected to a sub-filament, apparently 'falling' onto the clump. This filament runs parallel to the magnetic field. All observed kinematic features in the DR21 filament (velocity field, velocity dispersion, and infall), its filamentary morphology, and the existence of (a) sub-filament(s) can be explained if the DR21 filament was formed by the convergence of flows on large scales and is now in a state of global gravitational

  14. Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H2O, H218O, OH, 18OH, O I, HCN, and NH3

    NASA Astrophysics Data System (ADS)

    González-Alfonso, E.; Fischer, J.; Graciá-Carpio, J.; Sturm, E.; Hailey-Dunsheath, S.; Lutz, D.; Poglitsch, A.; Contursi, A.; Feuchtgruber, H.; Veilleux, S.; Spoon, H. W. W.; Verma, A.; Christopher, N.; Davies, R.; Sternberg, A.; Genzel, R.; Tacconi, L.

    2012-05-01

    Full range Herschel/PACS spectroscopy of the (ultra)luminous infrared galaxies NGC 4418 and Arp 220, observed as part of the SHINING key programme, reveals high excitation in H2O, OH, HCN, and NH3. In NGC 4418, absorption lines were detected with Elower > 800 K (H2O), 600 K (OH), 1075 K (HCN), and 600 K (NH3), while in Arp 220 the excitation is somewhat lower. While outflow signatures in moderate excitation lines are seen in Arp 220 as have been seen in previous studies, in NGC 4418 the lines tracing its outer regions are redshifted relative to the nucleus, suggesting an inflow with Ṁ ≲ 12 M⊙ yr-1. Both galaxies have compact and warm (Tdust ≳ 100 K) nuclear continuum components, together with a more extended and colder component that is much more prominent and massive in Arp 220. A chemical dichotomy is found in both sources: on the one hand, the nuclear regions have high H2O abundances, ~10-5, and high HCN/H2O and HCN/NH3 column density ratios of 0.1-0.4 and 2-5, respectively, indicating a chemistry typical of evolved hot cores where grain mantle evaporation has occurred. On the other hand, the high OH abundance, with OH/H2O ratios of ~0.5, indicates the effects of X-rays and/or cosmic rays. The nuclear media have high surface brightnesses (≳1013 L⊙/kpc2) and are estimated to be very thick (NH ≳ 1025 cm-2). While NGC 4418 shows weak absorption in H218O and 18OH, with a 16O-to-18O ratio of ≳250-500, the relatively strong absorption of the rare isotopologues in Arp 220 indicates 18O enhancement, with 16O-to-18O of 70-130. Further away from the nuclear regions, the H2O abundance decreases to ≲10-7 and the OH/H2O ratio is reversed relative to the nuclear region to 2.5-10. Despite the different scales and morphologies of NGC 4418, Arp 220, and Mrk 231, preliminary evidence is found for an evolutionary sequence from infall, hot-core like chemistry, and solar oxygen isotope ratio to high velocity outflow, disruption of the hot core chemistry and

  15. The Flux of Large Meteoroids Observed with Lunar Impact Monitoring

    NASA Technical Reports Server (NTRS)

    Cooke, W. J.; Suggs, R. M.; Moser, D. E.; Suggs, R. J.

    2014-01-01

    The flux of large meteoroids is not well determined due to relatively low number statistics, due mainly to the lack of collecting area available to meteor camera systems (10(2)-10(5) km2). Larger collecting areas are needed to provide reasonable statistics for flux calculations. The Moon, with millions of square kilometers of lunar surface, can be used as a detector for observing the population of large meteoroids in the tens of grams to kilogram mass range. This is accomplished by observing the flash of light produced when a meteoroid impacts the lunar surface, converting a portion of its kinetic energy to visible light detectable from Earth. A routine monitoring program at NASA's Marshall Space Flight Center has recorded over 300 impact flashes since early 2006. The program utilizes multiple 0.35 m (14 inch) Schmidt-Cassegrain telescopes, outfitted with video cameras using the 1/2 inch Sony EXview HAD CCDTM chip, to perform simultaneous observations of the earthshine hemisphere of the Moon when the lunar phase is between 0.1 and 0.5. This optical arrangement permits monitoring of approximately 3.8x10(6) km2 of lunar surface. A selection of 126 flashes recorded in 266.88 hours of photometric skies was analyzed, creating the largest and most homogeneous dataset of lunar impact flashes to date. Standard CCD photometric techniques outlined in [1] were applied to the video to determine the luminous energy, kinetic energy, and mass for each impactor, considering a range of luminous efficiencies. The flux to a limiting energy of 2.5x10(-6) kT TNT or 1.05×10(7) J is 1.03×10(-7) km(-2) hr(-1) and the flux to a limiting mass of 30 g is 6.14×10(-10) m(-2) yr(-1). Comparisons made with measurements and models of the meteoroid population indicate that the flux of objects in this size range is slightly lower (but within the error bars) than the power law distribution determined for the near Earth object population by [2].

  16. Optical and X-ray monitoring, Doppler imaging, and space motion of the young star Par 1724 in Orion

    NASA Astrophysics Data System (ADS)

    Neuhaeuser, R.; Wolk, S. J.; Torres, G.; Preibisch, Th.; Stout-Batalha, N. M.; Hatzes, A. P.; Frink, S.; Wichmann, R.; Covino, E.; Alcala, J. M.; Brandner, W.; Walter, F. M.; Sterzik, M. F.; Koehler, R.

    1998-06-01

    We present a detailed study of the young T Tauri star Par 1724, located 15 arc min north of the Trapezium cluster in Orion. Our extensive VRI photometric measurements confirm the rotational period to be 5.7 days. Repeated high-resolution spectra show variability in the radial velocity with the same period. A Doppler imaging analysis based on high-S/N high-resolution spectra yields an image showing a pronounced dark feature (spot) at relatively low latitude, which is responsible for most or all of the observed variability. Our high-resolution spectra yield a rotational velocity of v * sin i =~ 71 km s(-1) , a surface gravity of log g =~ 3, and a mean heliocentric radial velocity of ~ 23 km s(-1) , the latter being consistent with membership to the Orion association. The equivalent width of the lithium 6708 Angstroms line is variable, consistent with rotational modulation. The line is stronger when the spot is on the front side; the lithium abundance observed when the spot is on the back side is consistent with the primordial value. Many ROSAT X-ray observations show that Par 1724 is a strong and variable X-ray source. It has shown one of the most powerful X-ray flares. Our deep infrared imaging at high spatial resolution reveals no physically bound visual companions down to ~ 1 arc sec separations and a magnitude difference up to Delta R = 7 mag, and also no companion down to ~ 0.13 arc sec with Delta K = 2.5 mag. We also present the spectral energy distribution of Par 1724 and show that it does not display infrared excess. We estimate the bolometric luminosity to be ~ 49 Lsun, the spectral type to be K0, and the radius to be ~ 9 Rsun. Although Par 1724 appears to have lost all its circumstellar material, its bolometric luminosity places it very close to the stellar birth-line at an age of only ~ 2 * 10(5) years, with a mass of ~ 3 Msun. According to its present location and 3D space motion ( ~ 20 km s(-1) to the north relative to the cluster), Par 1724 may have

  17. Hydrochemical aspects of major Pacific and caribbean rivers of colombia hydrochemical aspects of major Pacific and caribbean rivers of colombia

    NASA Astrophysics Data System (ADS)

    Restrepo, J. D.

    2003-04-01

    Although the South American continent includes three of the largest river basins of the world, the Amazon, the Orinoco, and the Paraná, with some of the highest discharges and sediment loads, a number of comparatively smaller systems in Colombia carry a significant share of sediment and dissolved loads from the continent. Fifteen rivers west of the Cordilleras in South America discharge a combined 254 km3 yr-1 or 8020 m3 s-1 of water into the Pacific. The San Juan River has the highest water discharge (2550 m3 s-1), sediment load (16 x 106 t yr-1), and basin-wide sediment yield (1150 t km-2 yr-1) on the entire west coast of South America. The best estimate of total sediment load into the Pacific Ocean from both gauged and ungauged rivers is 96 x 106 t yr-1. These results in a sediment yield estimate of 1,260 t km-2 yr-1. Analysis of 22 rivers draining into the Caribbean Sea indicate that the combined water discharge and sediment load are 338 km3 yr-1 and 168 x 106 t yr-1, respectively, corresponding to a sediment yield for the Colombia Caribbean drainage basins of 541 t km-2 yr-1, or approximately half of the yield for the Pacific basins of Colombia. The Magdalena River, the largest river system in Colombia, has an annual discharge of 7,232 m3 s-1. Load measurements during the 21 year period yielded an annual sediment load of 144 x 106 t yr-1. The Magdalena has the highest sediment yield (559 t km-2 yr-1) of any medium-sized or large river along the entire east coast of South America and contributes 9% of the total sediment load discharged into the Atlantic Ocean from eastern South America. The concentrations of major dissolved constituents and mass transport rates for major Colombian rivers were based on averages calculated from monthly samples from 1990-1993. Ca2+ and Mg2+ are the dominant ions, indicating that the water corresponds to the rock-dominated type. Dissolved inorganic carbon, present mostly as bicarbonate ions, constitutes almost 50% of the total

  18. Nonthermal ionization and excitation in Type IIb supernova 1993J.

    NASA Astrophysics Data System (ADS)

    Utrobin, V. P.

    1996-02-01

    A non-LTE study of Type IIb supernova 1993J in the galaxy M 81 accounting for nonthermal ionization and line blocking effects is carried out. Hydrodynamical models and theoretical spectra clearly show that nonthermal ionization and excitation dominate after the second maximum, at day ~30, and play a decisive role in reproducing both a smooth tail of the light curve and an emergence of helium lines in the spectrum similar to those observed. Based on our model of supernova 1993J, we predict that the light curves of Type IIb supernovae should be subject to nonthermal ionization and excitation at earlier times than even that of supernova 1993J. To fit the bolometric and visual light curves of supernova 1993J, an outer layer of ~1Msun_ has to be helium-rich hydrogen shell with a hydrogen mass fraction of ~0.1. In this shell there is no nearly pure helium mantle as contrasted to most of the evolutionary models at the time of explosion. The fact that such a distribution of hydrogen results in a characteristic maximum of hydrogen number density at velocity of ~8600km/s in the expelled envelope is well consistent with late time observations of Hα emission at epochs of 0.5-1 year after the explosion. An emergence of helium lines between day 24 and day 30 illustrated by the evolution of calculated profile of the He I line λ6678A completely fits the spectral observations of supernova 1993J. The bolometric and visual light curves and the spectral evolution of helium lines are consistent with a mass of the ejected envelope of ~2.4Msun_ including a hydrogen mass of ~0.12Msun_, an explosion energy of ~1.6x10^51^ergs, and a mass of radioactive ^56^Ni of ~0.078Msun_. It is found that the bulk of the radioactive material should be confined to layers of the ejected envelope expanding with velocities less than ~3800km/s. In our model, the outburst of supernova 1993J is interpreted as the explosion of a ~4Msun_ red supergiant undergoing core collapse and leaving a neutron star in a

  19. The European nitrogen case.

    PubMed

    van Egmond, Klaas; Bresser, Ton; Bouwman, Lex

    2002-03-01

    The N budget for Europe (excluding the former Soviet Union) indicates that the 3 principal driving forces of the acceleration of the European N cycle are fertilizer production (14 Mt (mill. tonnes) N yr-1), fossil fuel combustion and other industry (3.3 Mt N yr-1) and import of N in various products (7.6 Mt N yr-1). The various leaks of reactive N species from European food, energy and industrial production systems are estimated and their effects on human health and terrestrial and aquatic ecosystems are assessed. Future European environmental policy measures to close the N cycle and to reduce leaks of reactive N can best focus on the three major driving forces, taking into consideration the possible consequences in the N cascade. Critical loads may be useful tools in determining N-emission ceilings and developing integrated policies for regulating N flows such as fertilizer use and imports and N levels.

  20. Long-Term Changes in the Periods of SX Phe

    NASA Astrophysics Data System (ADS)

    Landes, H.; Bambery, K. R.; Coates, D. W.; Thompson, K.

    2007-05-01

    We have used times of maximum light for SX Phe, obtained by ourselves and other workers over 55 years to study the behaviour of the fundamental and first overtone radial pulsation modes of the star. We find (1/P0)dP0/dt to be (+2.53 +/- 0.05) × 10-8 yr-1 and (1/P1)dP1/dt to be (-1.60 +/- 0.03) × 10-7 yr-1, which differ significantly from the value +1.9 × 10-9 yr-1 expected if the changes are due to standard evolution of the star. The residuals in O-C from a quadratic fit cannot be explained by a light-time effect in a binary. There is some evidence that the amplitudes of the two modes change slowly with time.

  1. The Gravity Probe B test of general relativity

    NASA Astrophysics Data System (ADS)

    Everitt, C. W. F.; Muhlfelder, B.; DeBra, D. B.; Parkinson, B. W.; Turneaure, J. P.; Silbergleit, A. S.; Acworth, E. B.; Adams, M.; Adler, R.; Bencze, W. J.; Berberian, J. E.; Bernier, R. J.; Bower, K. A.; Brumley, R. W.; Buchman, S.; Burns, K.; Clarke, B.; Conklin, J. W.; Eglington, M. L.; Green, G.; Gutt, G.; Gwo, D. H.; Hanuschak, G.; He, X.; Heifetz, M. I.; Hipkins, D. N.; Holmes, T. J.; Kahn, R. A.; Keiser, G. M.; Kozaczuk, J. A.; Langenstein, T.; Li, J.; Lipa, J. A.; Lockhart, J. M.; Luo, M.; Mandel, I.; Marcelja, F.; Mester, J. C.; Ndili, A.; Ohshima, Y.; Overduin, J.; Salomon, M.; Santiago, D. I.; Shestople, P.; Solomonik, V. G.; Stahl, K.; Taber, M.; Van Patten, R. A.; Wang, S.; Wade, J. R.; Worden, P. W., Jr.; Bartel, N.; Herman, L.; Lebach, D. E.; Ratner, M.; Ransom, R. R.; Shapiro, I. I.; Small, H.; Stroozas, B.; Geveden, R.; Goebel, J. H.; Horack, J.; Kolodziejczak, J.; Lyons, A. J.; Olivier, J.; Peters, P.; Smith, M.; Till, W.; Wooten, L.; Reeve, W.; Anderson, M.; Bennett, N. R.; Burns, K.; Dougherty, H.; Dulgov, P.; Frank, D.; Huff, L. W.; Katz, R.; Kirschenbaum, J.; Mason, G.; Murray, D.; Parmley, R.; Ratner, M. I.; Reynolds, G.; Rittmuller, P.; Schweiger, P. F.; Shehata, S.; Triebes, K.; VandenBeukel, J.; Vassar, R.; Al-Saud, T.; Al-Jadaan, A.; Al-Jibreen, H.; Al-Meshari, M.; Al-Suwaidan, B.

    2015-11-01

    The Gravity Probe B mission provided two new quantitative tests of Einstein’s theory of gravity, general relativity (GR), by cryogenic gyroscopes in Earth’s orbit. Data from four gyroscopes gave a geodetic drift-rate of -6601.8 ± 18.3 marc-s yr-1 and a frame-dragging of -37.2 ± 7.2 marc-s yr-1, to be compared with GR predictions of -6606.1 and -39.2 marc-s yr-1 (1 marc-s = 4.848 × 10-9 radians). The present paper introduces the science, engineering, data analysis, and heritage of Gravity Probe B, detailed in the accompanying 20 CQG papers.

  2. Twenty years of continuous high time resolution volatile organic compound monitoring in the United Kingdom from 1993 to 2012

    NASA Astrophysics Data System (ADS)

    Derwent, R. G.; Dernie, J. I. R.; Dollard, G. J.; Dumitrean, P.; Mitchell, R. F.; Murrells, T. P.; Telling, S. P.; Field, R. A.

    2014-12-01

    Continuous, high frequency observations of C2 - C8 hydrocarbons began in the United Kingdom in 1993 and have continued through to the present day at a range of kerbside, urban background and rural locations. Most of the monitored hydrocarbons have shown dramatic declines in concentrations over the study period, with present levels close to an order of magnitude below their levels in the 1990s. The concentrations of 23 selected hydrocarbons have been aggregated up to give an estimate of the total VOC concentrations. These annual values have shown an exponential decline of -18% yr-1 at the London Marylebone Road kerbside site, -11% yr-1 at the London Eltham urban background site and -22% yr-1 at the rural Harwell site. Similar declines have been reported in UK road transport VOC emissions, demonstrating how the VOC emission inventories have apparently captured the salient features influencing real-world VOC emissions over the 1994-2012 period.

  3. Methane production from mixed tropical savanna and forest vegetation in Venezuela

    NASA Astrophysics Data System (ADS)

    Crutzen, P. J.; Sanhueza, E.; Brenninkmeijer, C. A. M.

    2006-04-01

    Measurements of methane concentrations in the boundary layer in the northern part of the Guayana shield, Venezuela, during the wet season (October 1988), showed the presence of substantial methane surface emissions. The measuring site is within the savanna climate region, but is affected by emissions from savanna and forest vegetation. From day versus night concentration measurements, with higher concentrations during night, a methane source strength near the site of 3-7×1011 molecules/cm2/s can be estimated, which includes emissions from small tracts of flooded soils, termites and especially tropical vegetation. Extrapolated to the entire savanna, this may imply a methane source of ~30-60 Tg yr-1 similar to the one calculated for tropical vegetation on the basis of recently published in vitro plant emission experiments by Keppler et al. (2006), which indicate emissions of ~30 Tg yr-1 for tropical savannas and grasslands and ~78 Tg yr-1 for tropical forests.

  4. Mapping critical loads of nitrogen deposition for aquatic ecosystems in the Rocky Mountains, USA

    USGS Publications Warehouse

    Nanus, Leora; Clow, David W.; Saros, Jasmine E.; Stephens, Verlin C.; Campbell, Donald H.

    2012-01-01

    Spatially explicit estimates of critical loads of nitrogen (N) deposition (CLNdep) for nutrient enrichment in aquatic ecosystems were developed for the Rocky Mountains, USA, using a geostatistical approach. The lowest CLNdep estimates (-1 yr-1) occurred in high-elevation basins with steep slopes, sparse vegetation, and abundance of exposed bedrock and talus. These areas often correspond with areas of high N deposition (>3 kg N ha-1 yr-1), resulting in CLNdep exceedances ≥1.5 ± 1 kg N ha-1 yr-1. CLNdep and CLNdep exceedances exhibit substantial spatial variability related to basin characteristics and are highly sensitive to the NO3- threshold at which ecological effects are thought to occur. Based on an NO3- threshold of 0.5 μmol L-1, N deposition exceeds CLNdep in 21 ± 8% of the study area; thus, broad areas of the Rocky Mountains may be impacted by excess N deposition, with greatest impacts at high elevations.

  5. Esimating the emission of photopollutants from the city of Lagos from aircraft observations

    NASA Astrophysics Data System (ADS)

    Evans, M. J.; Hopkins, J.; Lee, J.; Lewis, A.; Marsham, J.; Parker, D.; Stewart, D.; Capes, G.; Williams, P.; Crosier, J.

    2007-12-01

    The city of Lagos, Nigeria is the second most populated city in Africa and by 2020 is likely to be the most populated. During the AMMA campaign in 2006 the UK BAe146 aircraft flew an orbit around the city observing the concentration of key photo-pollutants. This allowed the fluxes and thus emissions from the city to be calculated. We calculate CO, NOx and VOC emissions to be on the order of 1 Tg (CO) yr-1, 0.01 Tg (N) yr-1, 0.2 Tg (VOC) yr-1 respectively. Based upon a principal components analysis of the observations we split the emissions due to evaporative, low temperature combustion and high temperature combustion.

  6. Global distribution and sources of dissolved inorganic nitrogen export to the coastal zone: Results from a spatially explicit, global model

    NASA Astrophysics Data System (ADS)

    Dumont, E.; Harrison, J. A.; Kroeze, C.; Bakker, E. J.; Seitzinger, S. P.

    2005-12-01

    Here we describe, test, and apply a spatially explicit, global model for predicting dissolved inorganic nitrogen (DIN) export by rivers to coastal waters (NEWS-DIN). NEWS-DIN was developed as part of an internally consistent suite of global nutrient export models. Modeled and measured DIN export values agree well (calibration R2 = 0.79), and NEWS-DIN is relatively free of bias. NEWS-DIN predicts: DIN yields ranging from 0.0004 to 5217 kg N km-2 yr-1 with the highest DIN yields occurring in Europe and South East Asia; global DIN export to coastal waters of 25 Tg N yr-1, with 16 Tg N yr-1 from anthropogenic sources; biological N2 fixation is the dominant source of exported DIN; and globally, and on every continent except Africa, N fertilizer is the largest anthropogenic source of DIN export to coastal waters.

  7. Trace Metal Budgets for a Forested Watershed in the New Jersey Pine Barrens

    NASA Astrophysics Data System (ADS)

    Swanson, Karen A.; Johnson, Arthur H.

    1980-04-01

    Deposition of Pb, Cu, Ni, Fe, Mn, and Cd on the McDonalds Branch Basin in bulk precipitation was 25.4, 5.3, 6.6, 64.6, 20.7, and <2 mg m-2 yr-1 for a 1 year period in 1978-1979. Output in streamflow was 1.7, 0.7, 1.9, 148, 12.8, and <1 mg m-2 yr-1, respectively, and loss to deep groundwater was 1.4, 1.9, 2.3, 123, 20.4, and <1 mg m-2 yr-1. Pb, Cu, and Ni accumulated in the basin, while there was a net loss of Fe and Mn from the ecosystem. The major mechanism for movement of Fe and Pb out of the basin was interpreted to be complexation with and transport by mobile organic matter.

  8. The tropospheric cycle of H2: a critical review

    NASA Astrophysics Data System (ADS)

    Ehhalt, D. H.; Rohrer, F.

    2009-07-01

    The literature on the distribution, budget and isotope content of molecular hydrogen (H2) in the troposphere is critically reviewed. The global distribution of H2 is reasonably well established and is relatively uniform. The surface measurements exhibit a weak latitudinal gradient with 3% higher concentrations in the Southern Hemisphere and seasonal variations that maximize in arctic latitudes and the interior of continents with peak-to-peak amplitudes up to 10%. There is no evidence for a continuous long-term trend, but older data suggest a reversal of the interhemispheric gradient in the late 1970s, and an increase in the deuterium content of H2 in the Northern Hemisphere from 80‰ standard mean ocean water (SMOW) in the 1970s to 130‰ today. The current budget analyses can be divided in two classes: bottom up, in which the source and sink terms are estimated separately based on emission factors and turnovers of precursors and on global integration of regional loss rates, respectively. That category includes the analyses by 3-D models and furnishes tropospheric turnovers around 75 Tg H2 yr-1. The other approach, referred to as top down, relies on inverse modelling or analysis of the deuterium budget of tropospheric H2. These provide a global turnover of about 105 Tg H2 yr-1. The difference is due to a much larger sink strength by soil uptake and a much larger H2 production from the photochemical oxidation of volatile organic compounds (VOC) in the case of the top down approaches. The balance of evidence seems to favour the lower estimates-mainly due to the constraint placed by the global CO budget on the H2 production from VOC. An update of the major source and sink terms yields: fossil fuel use 11 +/- 4 Tg H2 yr-1 biomass burning (including bio-fuel) 15 +/- 6 Tg H2 yr-1 nitrogen fixation (ocean) 6 +/- 3 Tg H2 yr-1 nitrogen fixation (land) 3 +/- 2 Tg H2 yr-1 photochemical production from CH4 23 +/- 8 Tg H2 yr-1 and photochemical production from other VOC 18

  9. Fingerprinting Hydrogen in Core-Collapse Supernovae

    NASA Astrophysics Data System (ADS)

    Nance, Sarafina; Parrent, Jerod; Soderberg, Alicia Margarita

    2016-01-01

    This is a preliminary report on the mass of remaining hydrogen envelopes for stars massive enough to explode under core collapse. Using the stellar evolution code, MESA, our initial findings suggest that a significant fraction of massive stars with M_ZAMS = 20-60 Msun lose all but 10^-3 Msun -10^-1 Msun as they near eventual core collapse. This result is dependent on the mass-loss prescription, degree of rotation, metallicity, rates of nuclear burning in the core, and the final stellar configuration. Nevertheless, each of our test cases include a few stars that retain trace amounts of surface hydrogen, which would then be detected as faint H in type IIb/Ib/Ic supernova spectra. We also compare our findings to the progenitor candidate identified for iPTF13bvn using the most recent photometric corrections. We agree with the previous conclusion found by Groh et al. (2013) that the progenitor had an initial mass of 32 Msun, but now with an additional condition of 0.06 Msun of hydrogen on its surface just prior to the explosion. We demonstrate through our study that not all Type Ib supernovae are fully devoid of hydrogen at the time of explosion, which has implications for the nature of the progenitor star and thus provides impetus for a revised classification scheme for 'stripped envelope' supernovae. This work was supported in part by the NSF REU and DoD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.

  10. Two decades of ocean CO2 sink and variability

    NASA Astrophysics Data System (ADS)

    Le QuÉRÉ, C.; Aumont, O.; Bopp, L.; Bousquet, P.; Ciais, P.; Francey, R.; Heimann, M.; Keeling, C. D.; Keeling, R. F.; Kheshgi, H.; Peylin, P.; Piper, S. C.; Prentice, I. C.; Rayner, P. J.

    2003-04-01

    Atmospheric CO2 has increased at a nearly identical average rate of 3.3 and 3.2 Pg C yr-1 for the decades of the 1980s and the 1990s, in spite of a large increase in fossil fuel emissions from 5.4 to 6.3 Pg C yr-1. Thus, the sum of the ocean and land CO2 sinks was 1 Pg C yr-1 larger in the 1990s than in to the 1980s. Here we quantify the ocean and land sinks for these two decades using recent atmospheric inversions and ocean models. The ocean and land sinks are estimated to be, respectively, 0.3 (0.1 to 0.6) and 0.7 (0.4 to 0.9) Pg C yr-1 larger in the 1990s than in the 1980s. When variability less than 5 yr is removed, all estimates show a global oceanic sink more or less steadily increasing with time, and a large anomaly in the land sink during 1990-1994. For year-to-year variability, all estimates show 1/3 to 1/2 less variability in the ocean than on land, but the amplitude and phase of the oceanic variability remain poorly determined. A mean oceanic sink of 1.9 Pg C yr-1 for the 1990s based on O2 observations corrected for ocean outgassing is supported by these estimates, but an uncertainty on the mean value of the order of ±0.7 Pg C yr-1 remains. The difference between the two decades appears to be more robust than the absolute value of either of the two decades.

  11. Fluvial response to climate variations and anthropogenic perturbations for the Ebro River, Spain in the last 4,000 years.

    PubMed

    Xing, Fei; Kettner, Albert J; Ashton, Andrew; Giosan, Liviu; Ibáñez, Carles; Kaplan, Jed O

    2014-03-01

    Fluvial sediment discharge can vary in response to climate changes and human activities, which in return influences human settlements and ecosystems through coastline progradation and retreat. To understand the mechanisms controlling the variations of fluvial water and sediment discharge for the Ebro drainage basin, Spain, we apply a hydrological model HydroTrend. Comparison of model results with a 47-year observational record (AD 1953-1999) suggests that the model adequately captures annual average water discharge (simulated 408 m(3)s(-1) versus observed 425 m(3)s(-1)) and sediment load (simulated 0.3 Mt yr(-1) versus observed 0.28 ± 0.04 Mt yr(-1)) for the Ebro basin. A long-term (4000-year) simulation, driven by paleoclimate and anthropogenic land cover change scenarios, indicates that water discharge is controlled by the changes in precipitation, which has a high annual variability but no long-term trend. Modeled suspended sediment load, however, has an increasing trend over time, which is closely related to anthropogenic land cover variations with no significant correlation to climatic changes. The simulation suggests that 4,000 years ago the annual sediment load to the ocean was 30.5 Mt yr(-1), which increased over time to 47.2 Mt yr(-1) (AD 1860-1960). In the second half of the 20th century, the emplacement of large dams resulted in a dramatic decrease in suspended sediment discharge, eventually reducing the flux to the ocean by more than 99% (mean value changes from 38.1 Mt yr(-1) to 0.3 Mt yr(-1)).

  12. Growth of the Antarctic octocoral Primnoella scotiae and predation by the anemone Dactylanthus antarcticus

    NASA Astrophysics Data System (ADS)

    Peck, Lloyd S.; Brockington, Simon

    2013-08-01

    Growth rates in Antarctic marine ectotherms have been demonstrated to be slowed by two to five times compared to shallow-water temperate species, with no previous reports for octocorals. Here growth rates were estimated in the single axis, non-branching Antarctic octocoral Primnoella scotiae using repeated in situ length measures covering both summer and winter periods, for tagged colonies from three sites at Signy Island over a two year period. Mean rates of length increase at the different sites ranged from 0.96 mm yr-1 to 55.3 mm yr-1. The fastest individual colony growth rate at any site ranged from 2.55 mm yr-1 to 175.6 mm yr-1. The mean of the fastest growth rates across all sites was 33.0 mm yr-1±14.7 (s.e.). Growth was significantly different between sites, and also between seasons and years. The mean overall increase in diameter of the average sized colony in the study (222.5 mm in axis length) was 0.053 mm yr-1. This is the slowest reported growth rate of any octocoral to date, and is five times slower than growth in most cold water octocorals. During the study it was noted that colonies were being attacked and consumed by the anemone Dactylanthus antarcticus. At one of the sites studied, between 5% and 8% of colonies surveyed were attacked each month. Anemone dispersal was via whole body inflation and drifting to new prey colonies that were attached to using tentacle-like column protuberances.

  13. Radiation dose to workers due to the inhalation of dust during granite fabrication.

    PubMed

    Zwack, L M; McCarthy, W B; Stewart, J H; McCarthy, J F; Allen, J G

    2014-03-01

    There has been very little research conducted to determine internal radiation doses resulting from worker exposure to ionising radiation in granite fabrication shops. To address this issue, we estimated the effective radiation dose of granite workers in US fabrication shops who were exposed to the maximum respirable dust and silica concentrations allowed under current US regulations, and also to concentrations reported in the literature. Radiation doses were calculated using standard methods developed by the International Commission on Radiological Protection. The calculated internal doses were very low, and below both US occupational standards (50 mSv yr(-1)) and limits applicable to the general public (1 mSv yr(-1)). Workers exposed to respirable granite dust concentrations at the US Occupational Safety and Health Administration (OSHA) respirable dust permissible exposure limit (PEL) of 5 mg m(-3) over a full year had an estimated radiation dose of 0.062 mSv yr(-1). Workers exposed to respirable granite dust concentrations at the OSHA silica PEL and at the American Conference of Governmental Industrial Hygienists Threshold Limit Value for a full year had expected radiation doses of 0.007 mSv yr(-1) and 0.002 mSv yr(-1), respectively. Using data from studies of respirable granite dust and silica concentrations measured in granite fabrication shops, we calculated median expected radiation doses that ranged from <0.001 to 0.101 mSv yr(-1). PMID:24270240

  14. Responses to simulated nitrogen deposition by the neotropical epiphytic orchid Laelia speciosa.

    PubMed

    Díaz-Álvarez, Edison A; Lindig-Cisneros, Roberto; de la Barrera, Erick

    2015-01-01

    Potential ecophysiological responses to nitrogen deposition, which is considered to be one of the leading causes for global biodiversity loss, were studied for the endangered endemic Mexican epiphytic orchid, Laelia speciosa, via a shadehouse dose-response experiment (doses were 2.5, 5, 10, 20, 40, and 80 kg N ha(-1) yr(-1)) in order to assess the potential risk facing this orchid given impending scenarios of nitrogen deposition. Lower doses of nitrogen of up to 20 kg N ha yr(-1), the dose that led to optimal plant performance, acted as fertilizer. For instance, the production of leaves and pseudobulbs were respectively 35% and 36% greater for plants receiving 20 kg N ha yr(-1) than under any other dose. Also, the chlorophyll content and quantum yield peaked at 0.66 ± 0.03 g m(-2) and 0.85 ± 0.01, respectively, for plants growing under the optimum dose. In contrast, toxic effects were observed at the higher doses of 40 and 80 kg N ha yr(-1). The δ (13)C for leaves averaged -14.7 ± 0.2‰ regardless of the nitrogen dose. In turn, δ (15)N decreased as the nitrogen dose increased from 0.9 ± 0.1‰ under 2.5 kg N ha(-1)yr(-1) to -3.1 ± 0.2‰ under 80 kg N ha(-1)yr(-1), indicating that orchids preferentially assimilate NH4 (+) rather than NO3 (-) of the solution under higher doses of nitrogen. Laelia speciosa showed a clear response to inputs of nitrogen, thus, increasing rates of atmospheric nitrogen deposition can pose an important threat for this species.

  15. Far Ultraviolet Spectroscopy of Seven Nova-Like Variables

    NASA Astrophysics Data System (ADS)

    Mizusawa, Trisha; Merritt, Jason; Ballouz, Ronald-Louis; Bonaro, Michael; Foran, Sean; Plumberg, Christopher; Stewart, Heather; Wiley, Trayer; Sion, Edward M.

    2010-03-01

    We present the results of a multicomponent synthetic spectral analysis of the archival far ultraviolet spectra of several key nova-like variables including members of the SW Sex, RW Tri, UX UMa, and VY Scl subclasses: KR Aur, RW Tri, V825 Her, V795 Her, BP Lyn, V425 Cas, and HL Aqr. Accretion rates as well as the possible flux contribution of the accreting white dwarf are included in our analysis. Except for RW Tri, which has a reliable trigonometric parallax, we computed the distances to the nova-like systems using the method of Knigge. Our analysis of seven archival IUE spectra of RW Tri at its parallax distance of 341 pc consistently indicates a low mass (~0.4 Msolar) white dwarf and an average accretion rate, {\\overset{.}{M}} = 6.3 × 10-9 Msolar yr-1. For KR Aur, we estimate that the white dwarf has Teff = 29,000 ± 2000 K, log g = 8.4, and contributes 18% of the far-UV flux, while an accretion disk with accretion rate {\\overset{.}{M}} = 3 × 10-10 Msolar yr-1 at an inclination of 41° contributes the remainder. We find that an accretion disk dominates the far-UV spectrum of V425 Cas but a white dwarf contributes nonnegligibly with approximately 18% of the far-UV flux. For the two high state nova-likes, HL Aqr and V825 Her, their accretion disks totally dominate with {\\overset{.}{M}} = 1 × 10-9 Msolar yr-1 and 3 × 10-9 Msolar yr-1, respectively. For BP Lyn we find {\\overset{.}{M}} = 1 × 10-8 Msolar yr-1 while for V795 Her, we find an accretion rate of {\\overset{.}{M}} = 1 × 10-10 Msolar yr-1. We discuss the implications of our results for the evolutionary status of nova-like variables.

  16. Sphagnum can 'filter' N deposition, but effects on the plant and pore water depend on the N form.

    PubMed

    Chiwa, Masaaki; Sheppard, Lucy J; Leith, Ian D; Leeson, Sarah R; Tang, Y Sim; Cape, J Neil

    2016-07-15

    The ability of Sphagnum moss to efficiently intercept atmospheric nitrogen (N) has been assumed to be vulnerable to increased N deposition. However, the proposed critical load (20kgNha(-1)yr(-1)) to exceed the capacity of the Sphagnum N filter has not been confirmed. A long-term (11years) and realistic N manipulation on Whim bog was used to study the N filter function of Sphagnum (Sphagnum capillifolium) in response to increased wet N deposition. On this ombrotrophic peatland where ambient deposition was 8kgNha(-1)yr(-1), an additional 8, 24, and 56kgNha(-1)yr(-1) of either ammonium (NH4(+)) or nitrate (NO3(-)) has been applied for 11years. Nutrient status of Sphagnum and pore water quality from the Sphagnum layer were assessed. The N filter function of Sphagnum was still active up to 32kgNha(-1)yr(-1) even after 11years. N saturation of Sphagnum and subsequent increases in dissolved inorganic N (DIN) concentration in pore water occurred only for 56kgNha(-1)yr(-1) of NH4(+) addition. These results indicate that the Sphagnum N filter is more resilient to wet N deposition than previously inferred. However, functionality will be more compromised when NH4(+) dominates wet deposition for high inputs (56kgNha(-1)yr(-1)). The N filter function in response to NO3(-) uptake increased the concentration of dissolved organic N (DON) and associated organic anions in pore water. NH4(+) uptake increased the concentration of base cations and hydrogen ions in pore water though ion exchange. The resilience of the Sphagnum N filter can explain the reported small magnitude of species change in the Whim bog ecosystem exposed to wet N deposition. However, changes in the leaching substances, arising from the assimilation of NO3(-) and NH4(+), may lead to species change. PMID:27058130

  17. Shifts in vegetation growth in response to multiple factors on the Mongolian Plateau from 1982 to 2011

    NASA Astrophysics Data System (ADS)

    Miao, Lijuan; Liu, Qiang; Fraser, Richard; He, Bin; Cui, Xuefeng

    The Mongolian Plateau (MP) steppe is one of the largest steppe environments in the world. To monitor the terrestrial vegetation dynamics on the MP and to ascertain what the driving forces, this study examined the vegetation dynamics in Republic of Mongolia (M) and the Inner Mongolia Autonomous Region (IM) of China from the period 1982 to 2011, based on the satellite-derived GIMMS NDVI3g (Normalized Difference Vegetation Index) data across three biomes (desert, grassland and forest). The results are as followed: (1) Vegetation coverage in IM was generally greater than that in M. Before 2002, time series of NDVI over the MP increased at an average rate of 0.05% yr-1. Additionally, after 2002, the NDVI increased at a rate of 0.21% yr-1. From 1982 to 2011, the area of IM and M with positive anomalies in the NDVI increased at a separate rate of 1.82% yr-1 and 1.76% yr-1, respectively. (2) At the biome scale, the inter-annual forest NDVI variation in IM and desert NDVI for the entire MP had a significant increasing trend (0.06% yr-1 and 0.04% yr-1, respectively). (3) Climate forcing was a dominant controlling factor affecting the vegetation, and the anthropogenic behavior exhibited no significant value in the whole region. However, overgrazing was the most important reason for the regional degradation, particularly in IM. (4) In the future, the forest biome will go to recovery, whereas both the grassland and desert biomes are predicted to degrade continuously.

  18. Energy Use and Carbon Dioxide Emissions from Cropland Production in the United States, 1990-2004

    SciTech Connect

    West, Tristram O.; Brandt, Craig C; Marland, Gregg; Nelson, Richard G; Hellwinckel, Chad M; De La Torre Ugarte, Daniel G

    2009-01-01

    Changes in cropland production and management influence energy consumption and emissions of CO2 from fossil-fuel combustion. A method was developed to calculate on-site and off-site energy and CO2 emissions for cropping practices in the US at the county scale. Energy consumption and emissions occur on-site from the operation of farm machinery and occur off-site from the manufacture and transport of cropland production inputs, such as fertilizers, pesticides, and agricultural lime. Estimates of fossil-fuel consumption and associated CO2 emissions for cropping practices enable (a) the monitoring of energy and emissions with changes in land management, and (b) the calculation and balancing of regional and national carbon budgets. Results indicate on-site energy use and total energy use (i.e., the sum of on-site and off-site) on US croplands in 2004 ranged from 1.6-7.9 GJ ha-1 yr-1 and from 5.5-20.5 GJ ha-1 yr-1, respectively. On-site and total CO2 emissions in 2004 ranged from 23-176 kg C ha-1 yr-1 and from 91-365 kg C ha-1 yr-1, respectively. During the period of this analysis (1990-2004), national total energy consumption for crop production ranged from 1204-1297 PJ yr-1 (Petajoule = 1 1015 Joule) with associated total fossil CO2 emissions ranging from 22.0-23.2 Tg C yr-1 (Teragram = 1 1012 gram). The annual proportion of on-site CO2 to total CO2 emissions changed depending on the diversity of crops planted. Adoption of reduced tillage practices in the US from 1990 to 2004 resulted in a net emissions reduction of 2.4 Tg C.

  19. Responses to simulated nitrogen deposition by the neotropical epiphytic orchid Laelia speciosa.

    PubMed

    Díaz-Álvarez, Edison A; Lindig-Cisneros, Roberto; de la Barrera, Erick

    2015-01-01

    Potential ecophysiological responses to nitrogen deposition, which is considered to be one of the leading causes for global biodiversity loss, were studied for the endangered endemic Mexican epiphytic orchid, Laelia speciosa, via a shadehouse dose-response experiment (doses were 2.5, 5, 10, 20, 40, and 80 kg N ha(-1) yr(-1)) in order to assess the potential risk facing this orchid given impending scenarios of nitrogen deposition. Lower doses of nitrogen of up to 20 kg N ha yr(-1), the dose that led to optimal plant performance, acted as fertilizer. For instance, the production of leaves and pseudobulbs were respectively 35% and 36% greater for plants receiving 20 kg N ha yr(-1) than under any other dose. Also, the chlorophyll content and quantum yield peaked at 0.66 ± 0.03 g m(-2) and 0.85 ± 0.01, respectively, for plants growing under the optimum dose. In contrast, toxic effects were observed at the higher doses of 40 and 80 kg N ha yr(-1). The δ (13)C for leaves averaged -14.7 ± 0.2‰ regardless of the nitrogen dose. In turn, δ (15)N decreased as the nitrogen dose increased from 0.9 ± 0.1‰ under 2.5 kg N ha(-1)yr(-1) to -3.1 ± 0.2‰ under 80 kg N ha(-1)yr(-1), indicating that orchids preferentially assimilate NH4 (+) rather than NO3 (-) of the solution under higher doses of nitrogen. Laelia speciosa showed a clear response to inputs of nitrogen, thus, increasing rates of atmospheric nitrogen deposition can pose an important threat for this species. PMID:26131375

  20. Methane emissions in East Asia for 2000-2011 estimated using an atmospheric Bayesian inversion

    NASA Astrophysics Data System (ADS)

    Thompson, R. L.; Stohl, A.; Zhou, L. X.; Dlugokencky, E.; Fukuyama, Y.; Tohjima, Y.; Kim, S.-Y.; Lee, H.; Nisbet, E. G.; Fisher, R. E.; Lowry, D.; Weiss, R. F.; Prinn, R. G.; O'Doherty, S.; Young, D.; White, J. W. C.

    2015-05-01

    We present methane (CH4) emissions for East Asia from a Bayesian inversion of CH4 mole fraction and stable isotope (δ13C-CH4) measurements. Emissions were estimated at monthly resolution from 2000 to 2011. A posteriori, the total emission for East Asia increased from 43 ± 4 to 59 ± 4 Tg yr-1 between 2000 and 2011, owing largely to the increase in emissions from China, from 39 ± 4 to 54 ± 4 Tg yr-1, while emissions in other East Asian countries remained relatively stable. For China, South Korea, and Japan, the total emissions were smaller than the prior estimates (i.e., Emission Database for Global Atmospheric Research 4.2 FT2010 for anthropogenic emissions) by an average of 29%, 20%, and 23%, respectively. For Mongolia, Taiwan, and North Korea, the total emission was less than 2 Tg yr-1 and was not significantly different from the prior. The largest reductions in emissions, compared to the prior, occurred in summer in regions important for rice agriculture suggesting that this source is overestimated in the prior. Furthermore, an analysis of the isotope data suggests that the prior underestimates emissions from landfills and ruminant animals for winter 2010 to spring 2011 (no data available for other times). The inversion also found a lower average emission trend for China, 1.2 Tg yr-1 compared to 2.8 Tg yr-1 in the prior. This trend was not constant, however, and increased significantly after 2005, up to 2.0 Tg yr-1. Overall, the changes in emissions from China explain up to 40% of the increase in global emissions in the 2000s.