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. 46 CFR 59.10-5 - Cracks.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Cracks. 59.10-5 Section 59.10-5 Shipping COAST GUARD... APPURTENANCES Welding Repairs to Boilers and Pressure Vessels in -Service § 59.10-5 Cracks. (a) Cracks extending... cracks are veed out so that complete penetration of the weld metal is secured. (b) Circumferential...

  3. 46 CFR 105.10-5 - Approved.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Approved. 105.10-5 Section 105.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS COMMERCIAL FISHING VESSELS DISPENSING PETROLEUM PRODUCTS Definition of Terms Used in This Part § 105.10-5 Approved. (a) The...

  4. 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...

  5. 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 SECURITY INFORMATION OR AN EMPLOYMENT CLEARANCE General Provisions § 10.5 Definitions. Access...

  6. 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...

  7. 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...

  8. 10 CFR 10.5 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 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...

  9. Testing Low-Mass Stellar Models: Three New Detached Eclipsing Binaries below 0.75Msun

    NASA Astrophysics Data System (ADS)

    López-Morales, M.; Shaw, J. S.

    2007-06-01

    Full tests of stellar models below 1Msun have been hindered until now by the scarce number of precise measurements of the stars' most fundamental parameters: their masses and radii. With current observational techniques, the required precision to distinguish between different models (errors < 2-3 %) can only be achieved using detached eclipsing binaries where 1) both stars are similar in mass, i.e. q = M1/M2 ˜ 1.0, and 2) each star is a main sequence object below 1Msun. Until 2003 only three such binaries had been found and analyzed in detail. Two new systems were published in 2005 (Creevey et al.; López-Morales & Ribas), almost doubling the previous number of data points. Here we present preliminary results for 3 new low-mass detached eclipsing binaries. These are the first studied systems from our sample of 41 new binaries (Shaw & López-Morales, this proceedings). We also provide an updated comparison between the Mass-Radius and the Mass-Teff relations predicted by the models and the observational data from detached eclipsing binaries.

  10. 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...

  11. 43 CFR 10.5 - Consultation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Consultation. 10.5 Section 10.5 Public Lands: Interior Office of the Secretary of the Interior NATIVE AMERICAN GRAVES PROTECTION AND REPATRIATION REGULATIONS Human Remains, Funerary Objects, Sacred Objects, or Objects of Cultural Patrimony...

  12. 43 CFR 10.5 - Consultation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 1 2011-10-01 2011-10-01 false Consultation. 10.5 Section 10.5 Public Lands: Interior Office of the Secretary of the Interior NATIVE AMERICAN GRAVES PROTECTION AND REPATRIATION REGULATIONS Human Remains, Funerary Objects, Sacred Objects, or Objects of Cultural Patrimony...

  13. 43 CFR 10.5 - Consultation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 1 2012-10-01 2011-10-01 true Consultation. 10.5 Section 10.5 Public Lands: Interior Office of the Secretary of the Interior NATIVE AMERICAN GRAVES PROTECTION AND REPATRIATION REGULATIONS Human Remains, Funerary Objects, Sacred Objects, or Objects of Cultural Patrimony...

  14. 43 CFR 10.5 - Consultation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 1 2014-10-01 2014-10-01 false Consultation. 10.5 Section 10.5 Public Lands: Interior Office of the Secretary of the Interior NATIVE AMERICAN GRAVES PROTECTION AND REPATRIATION REGULATIONS Human Remains, Funerary Objects, Sacred Objects, or Objects of Cultural Patrimony...

  15. 43 CFR 10.5 - Consultation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 1 2013-10-01 2013-10-01 false Consultation. 10.5 Section 10.5 Public Lands: Interior Office of the Secretary of the Interior NATIVE AMERICAN GRAVES PROTECTION AND REPATRIATION REGULATIONS Human Remains, Funerary Objects, Sacred Objects, or Objects of Cultural Patrimony...

  16. Intracellular distribution of fatty alcohol oxidase activity in Mucor circinelloides YR-1 isolated from petroleum contaminated soils.

    PubMed

    Silva-Jiménez, Hortencia; Zazueta-Novoa, Vanesa; Durón-Castellanos, Arelí; Rodríguez-Robelo, Carmen; Leal-Morales, Carlos A; Zazueta-Sandoval, Roberto

    2009-11-01

    In previous studies, Mucor circinelloides YR-1 isolated from petroleum-contaminated soils grown in decane as sole carbon source, showed fatty alcohol oxidase (FAO) activities in either particulate or soluble fractions from a cell-free extract. One is associated to internal membranes (mFAO) and the other one is soluble (sFAO). Both activities appear to be located in the cells in specific compartments other than peroxisomes. Results suggested that mFAO could be located on the inner face of the membrane of these compartments, and sFAO could be in the lumen of the specific compartments. This study reports on the intracellular distribution of FAO activity and the purification of sFAOs and mFAO after several different procedures for release from the membranous fraction using the mixed membrane fraction (MMF) after cellular homogenization as enzymatic source. Results with the purified mFAO show, by molecular weight criteria, that the enzyme has only one type of subunit with molecular mass of 46 kDa, with two isoelectric point components: 6.0 and 6.3. We found that mFAO is strongly associated to the MMF, possibly in a transitory fashion. Using non-denaturating gels, we suggest that sFAO and mFAO have the same subunits in their native structures, and, due to their native molecular weight of approximately 350 kDa, each could be natively structured as an octameric complex.

  17. 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...

  18. 46 CFR 59.10-5 - Cracks.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 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. (e... any direction, nor more than a total of four cracks in a drum, and further provided the welding...

  19. 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... EQUIPMENT Fire Main System, Details § 193.10-5 Fire pumps. (a) Vessels shall be equipped with independently driven fire pumps in accordance with Table 193.10-5(a). Table 193.10-5(a) Gross tons Over Not...

  20. 46 CFR 193.10-5 - Fire pumps.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Fire pumps. 193.10-5 Section 193.10-5 Shipping COAST... EQUIPMENT Fire Main System, Details § 193.10-5 Fire pumps. (a) Vessels shall be equipped with independently driven fire pumps in accordance with Table 193.10-5(a). Table 193.10-5(a) Gross tons Over Not...

  1. 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...

  2. 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...

  3. Registration of cotton germplasm line md 10-5

    Technology Transfer Automated Retrieval System (TEKTRAN)

    MD 10-5 (Reg. No. ______, PI 675077) is a noncommercial breeding line of cotton (Gossypium hirsutum L.) released by the USDA-ARS at Stoneville, MS in 2015. MD 10-5 was selected in F4 progenies from a cross between MD 15 (PI 642769) and JJ 1145ne. MD 10-5 has a desirable combination between lint yi...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  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 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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... SYSTEMS AND EQUIPMENT Fire and Smoke Detecting and Alarm Systems § 113.10-5 Common return. A conductor must not be used as a common return from more than one zone....

  1. 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,...

  2. 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,...

  3. 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,...

  4. 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,...

  5. 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,...

  6. 46 CFR 58.10-5 - Gasoline engine installations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 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 2013-10-01 2013-10-01 false Gasoline engine installations. 58.10-5 Section...

  7. 46 CFR 58.10-5 - Gasoline engine installations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 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 2011-10-01 2011-10-01 false Gasoline engine installations. 58.10-5 Section...

  8. 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...

  9. 46 CFR 58.10-5 - Gasoline engine installations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 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 2014-10-01 2014-10-01 false Gasoline engine installations. 58.10-5 Section...

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

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 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 2012-10-01 2012-10-01 false Gasoline engine installations. 58.10-5 Section...

  11. 33 CFR 67.10-5 - Location requirements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 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...

  12. 33 CFR 67.10-5 - Location requirements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 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...

  13. 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...

  14. 33 CFR 67.10-5 - Location requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 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...

  15. 33 CFR 67.10-5 - Location requirements.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 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...

  16. 46 CFR 193.10-5 - Fire main system, details.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... equipped with independently driven fire pumps in accordance with Table 193.10-5(a). Table 193.10-5(a) Gross tons Over Not over Minimum number of pumps Hose and hydrant size, inches Nozzle orifice size, inches... together with a commercial garden hose nozzle may be used. The pump may be hand operated and the length...

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

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... equipped with independently driven fire pumps in accordance with Table 193.10-5(a). Table 193.10-5(a) Gross tons Over Not over Minimum number of pumps Hose and hydrant size, inches Nozzle orifice size, inches... together with a commercial garden hose nozzle may be used. The pump may be hand operated and the length...

  18. 46 CFR 193.10-5 - Fire main system, details.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... equipped with independently driven fire pumps in accordance with Table 193.10-5(a). Table 193.10-5(a) Gross tons Over Not over Minimum number of pumps Hose and hydrant size, inches Nozzle orifice size, inches... together with a commercial garden hose nozzle may be used. The pump may be hand operated and the length...

  19. 46 CFR 95.10-5 - Fire pumps.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... on an international voyage, each required fire pump, while delivering water thru the fire main system... pumps shall be fitted with a pressure gage on the discharge side of the pumps. (f) Fire pumps may be... 46 Shipping 4 2011-10-01 2011-10-01 false Fire pumps. 95.10-5 Section 95.10-5 Shipping COAST...

  20. 46 CFR 95.10-5 - Fire pumps.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... on an international voyage, each required fire pump, while delivering water thru the fire main system... pumps shall be fitted with a pressure gage on the discharge side of the pumps. (f) Fire pumps may be... 46 Shipping 4 2014-10-01 2014-10-01 false Fire pumps. 95.10-5 Section 95.10-5 Shipping COAST...

  1. 46 CFR 95.10-5 - Fire pumps.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... on an international voyage, each required fire pump, while delivering water thru the fire main system... pumps shall be fitted with a pressure gage on the discharge side of the pumps. (f) Fire pumps may be... 46 Shipping 4 2013-10-01 2013-10-01 false Fire pumps. 95.10-5 Section 95.10-5 Shipping COAST...

  2. On the Evolution of Stars That Form Electron-degenerate Cores Processed by Carbon Burning. II. Isotope Abundances and Thermal Pulses in a 10 Msun Model with an ONe Core and Applications to Long-Period Variables, Classical Novae, and Accretion-induced Collapse

    NASA Astrophysics Data System (ADS)

    Ritossa, Claudio; Garcia-Berro, Enrique; Iben, Icko, Jr.

    1996-03-01

    long-period variables in the Galaxy and in the Magellanic Clouds. Perhaps the major signature of a TPSAGB star is a brightness greater than the "classical limit" of Mbol = -7.1. Betelgeuse in our Galaxy and four stars in the Magellanic Clouds are brighter than the supposed limit, but they exhibit abundance characteristics which can be accounted for in the framework of TPSAGB theory. Assuming that a superwind removes mass from the surface at a rate of ˜10-4 Msun yr-1, the final mass of the ONe white dwarf formed by our TPSAGB model is ˜1.26 Msun, the outer 0.06 Msun of which is composed primarily of carbon and oxygen.

  3. 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...

  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. 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...

  6. 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...

  7. 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...

  8. Polarization-entangled light pulses of 10(5) photons.

    PubMed

    Iskhakov, Timur Sh; Agafonov, Ivan N; Chekhova, Maria V; Leuchs, Gerd

    2012-10-12

    We experimentally demonstrate polarization entanglement for squeezed vacuum pulses containing more than 10(5) photons. We also study photon-number entanglement by calculating the Schmidt number and measuring its operational counterpart. Theoretically, our pulses are the more entangled the brighter they are. This promises important applications in quantum technologies, especially photonic quantum gates and quantum memories.

  9. 15 CFR 10.5 - Development of a recommended standard.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Development of a recommended standard... DEVELOPMENT OF VOLUNTARY PRODUCT STANDARDS § 10.5 Development of a recommended standard. (a) The Standard... proposal, after consulting with the proponent group, so that these requirements are met,...

  10. The Solar Neighborhood. XXII. Parallax Results from the CTIOPI 0.9 m Program: Trigonometric Parallaxes of 64 Nearby Systems with 0farcs5 <=μ<= 1farcs0 yr-1 (SLOWMO Sample)

    NASA Astrophysics Data System (ADS)

    Riedel, Adric R.; Subasavage, John P.; Finch, Charlie T.; Jao, Wei-Chun; Henry, Todd J.; Winters, Jennifer G.; Brown, Misty A.; Ianna, Philip A.; Costa, Edgardo; Mendez, Rene A.

    2010-09-01

    We present trigonometric parallaxes of 64 stellar systems with proper motions between 0farcs5 yr-1 and 1farcs0 yr-1 from the ongoing Research Consortium On Nearby Stars parallax program at the Cerro Tololo Inter-American Observatory. All of the systems are south of decl. =+30, and 58 had no previous trigonometric parallaxes. In addition to parallaxes for the systems, we present proper motions, Johnson-Kron-Cousins VRI photometry, variability measurements, and spectral types. Nine of the systems are multiple; we present results for their components, three of which are new astrometric detections. Of the 64 systems, 56 are within 25 pc of the Sun and 52 of those are in the southern hemisphere, comprising 5.7% of the total number of known southern 25 pc systems.

  11. The 0.4-Msun eclipsing binary CU Cancri. Absolute dimensions, comparison with evolutionary models and possible evidence for a circumstellar dust disk

    NASA Astrophysics Data System (ADS)

    Ribas, I.

    2003-01-01

    Photometric observations in the R and I bands of the detached M-type double-lined eclipsing binary CU Cnc have been acquired and analysed. The photometric elements obtained from the analysis of the light curves have been combined with an existing spectroscopic solution to yield high-precision (errors la 2%) absolute dimensions: MA=0.4333+/-0.0017 Msun, MB= 0.3980+/-0.0014 Msun, RA=0.4317+/-0.0052 Rsun, and RB=0.3908+/-0.0094 Rsun. The mean effective temperature of the system has been estimated to be Teff= 3140+/-150 K by comparing multi-band photometry (optical and infrared) with synthetic colors computed from state-of-the-art model atmospheres. Additionally, we have been able to obtain an estimate for the age ( ~ 320 Myr) and chemical composition ([Fe/H]~ 0.0) of the binary system through its membership of the Castor moving group. With all these observational constraints, we have carried out a critical test of recent stellar models for low-mass stars. The comparison reveals that most evolutionary models underestimate the radius of the stars by as much as 10%, thus confirming the trend observed by Torres & Ribas (\\cite{TR02}) for YY Gem and V818 Tau. In the mass-absolute magnitude diagram, CU Cnc is observed to be dimmer than other stars of the same mass and this makes the comparison with stellar models not so compelling. After ruling out a number of different scenarios, the apparent faintness of CU Cnc can be explained if its components are some 10% cooler than similar-mass stars or if there is some source of circumstellar dust absorption. The latter could be a tantalizing indirect evidence for a coplanar (Vega-like) dusty disk around this relatively young M-type binary. Tables 1 and 2 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.125.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/398/239}

  12. 46 CFR 3.10-5 - Renewal of letter of designation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Renewal of letter of designation. 3.10-5 Section 3.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PROCEDURES APPLICABLE TO THE PUBLIC DESIGNATION OF OCEANOGRAPHIC RESEARCH VESSELS Designation § 3.10-5 Renewal of letter of designation. At least 60 days prior...

  13. 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....

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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,...

  2. 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,...

  3. 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,...

  4. 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,...

  5. 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,...

  6. 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...

  7. 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...

  8. 46 CFR 12.10-5 - Examination and demonstration of ability.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Examination and demonstration of ability. 12.10-5 Section 12.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY MERCHANT MARINE OFFICERS AND SEAMEN..., whether administered orally or by other means, must be conducted only in the English language and...

  9. 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... transport a mobile home over water? Yes, you may transport a mobile home over water when both the points...

  10. 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...-5b Cargo control station—TB/ALL. The term cargo control station means a location that is manned during cargo transfer operations for the purpose of directing or controlling the loading or unloading...

  11. 41 CFR 302-10.5 - May I transport a mobile home over water?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 41 Public Contracts and Property Management 4 2013-07-01 2012-07-01 true May I transport a mobile home over water? 302-10.5 Section 302-10.5 Public Contracts and Property Management Federal Travel... transport a mobile home over water? Yes, you may transport a mobile home over water when both the points...

  12. 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... transport a mobile home over water? Yes, you may transport a mobile home over water when both the points...

  13. 46 CFR 54.10-5 - Maximum allowable working pressure (reproduces UG-98).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... ENGINEERING PRESSURE VESSELS Inspection, Reports, and Stamping § 54.10-5 Maximum allowable working pressure...) that are likely to occur, or the designated coincident operating temperature, excluding any...

  14. 19 CFR 10.5 - Shooks and staves; cloth boards; port director's account.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 1 2013-04-01 2013-04-01 false Shooks and staves; cloth boards; port director's... Provisions Articles Exported and Returned § 10.5 Shooks and staves; cloth boards; port director's account. (a... record of cloth boards of domestic manufacture exported to be wrapped with foreign textiles shall be...

  15. 19 CFR 10.5 - Shooks and staves; cloth boards; port director's account.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 1 2012-04-01 2012-04-01 false Shooks and staves; cloth boards; port director's... Provisions Articles Exported and Returned § 10.5 Shooks and staves; cloth boards; port director's account. (a... record of cloth boards of domestic manufacture exported to be wrapped with foreign textiles shall be...

  16. 19 CFR 10.5 - Shooks and staves; cloth boards; port director's account.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 1 2011-04-01 2011-04-01 false Shooks and staves; cloth boards; port director's... Provisions Articles Exported and Returned § 10.5 Shooks and staves; cloth boards; port director's account. (a... record of cloth boards of domestic manufacture exported to be wrapped with foreign textiles shall be...

  17. 19 CFR 10.5 - Shooks and staves; cloth boards; port director's account.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 1 2014-04-01 2014-04-01 false Shooks and staves; cloth boards; port director's... Provisions Articles Exported and Returned § 10.5 Shooks and staves; cloth boards; port director's account. (a... record of cloth boards of domestic manufacture exported to be wrapped with foreign textiles shall be...

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 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...

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 46 CFR 31.10-5 - Inspection of new tank vessels-TB/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... district in which the vessel is to be built; and one set shall be retained at the Marine Safety Center. If... such tank vessel is classed by the American Bureau of Shipping or other recognized classification... 46 Shipping 1 2014-10-01 2014-10-01 false Inspection of new tank vessels-TB/ALL. 31.10-5...

  4. 46 CFR 31.10-5 - Inspection of new tank vessels-TB/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... district in which the vessel is to be built; and one set shall be retained at the Marine Safety Center. If... such tank vessel is classed by the American Bureau of Shipping or other recognized classification... 46 Shipping 1 2013-10-01 2013-10-01 false Inspection of new tank vessels-TB/ALL. 31.10-5...

  5. Measurements of charm meson production in 10.5 GeV electron-positron annihilations

    NASA Astrophysics Data System (ADS)

    Johnson, Edward Eric

    A study of charm meson production in e+ e- γ* --> cc¯ events at s = 10.5 GeV is presented. Included are measurements of the fragmentation distributions of D+s and D*+s , the vector to pseudoscalar production ratio for Ds, and the D*+ spin alignment. A description of the new trigger designed for the CLEO III detector is also provided.

  6. Optical characterizations and electronic devices of nearly pure (10,5) single-walled carbon nanotubes.

    PubMed

    Zhang, Li; Tu, Xiaomin; Welsher, Kevin; Wang, Xinran; Zheng, Ming; Dai, Hongjie

    2009-02-25

    It remains an elusive goal to achieve high-performance single-walled carbon nanotube (SWNT) field-effect transistors (FETs) composed of only single-chirality SWNTs. Many separation mechanisms have been devised and various degrees of separation demonstrated, yet it is still difficult to reach the goal of total fractionation of a given nanotube mixture into its single-chirality components. Chromatography has been reported to separate small SWNTs (diameter < or = 0.9 nm) according to their diameter, chirality, and length. The separation efficiency decreased with increasing tube diameter when the ssDNA sequence d(GT)(n) (n = 10-45) was used. Here we report our results on the separation of single-chirality (10,5) SWNTs (diameter = 1.03 nm) from HiPco tubes using ion-exchange chromatography. The separation efficiency was improved by using the new DNA sequence (TTTA)(3)T, which can recognize SWNTs with the specific chirality (10,5). The chirality of the separated tubes was examined by optical absorption, Raman, photoluminescence excitation/emission, and electrical transport measurements. All of the spectroscopic methods gave a single peak of (10,5) tubes. The purity was 99% according to the electrical measurement. The FETs composed of separated SWNTs in parallel gave an I(on)/I(off) ratio up to 10(6) due to the single-chirality-enriched (10,5) tubes. This is the first time that SWNT FETs with single-chirality SWNTs have been achieved. The chromatography method has the potential to separate even larger diameter semiconducting SWNTs from other starting materials to further improve the performance of the SWNT FETs.

  7. 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...

  8. 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

  9. 10.5% efficient polymer and amorphous silicon hybrid tandem photovoltaic cell

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  10. Pion interference correlations in pion-nucleus collisions at 10. 5 GeV/c

    SciTech Connect

    Wong, R.

    1983-01-01

    Inclusive reactions of pion, Ne collisions at 10.5 GeV/c have been studied. The pion intensity interference effect has been observed in identical pion (..pi../sup +/, ..pi../sup -/, and ..pi../sup -/, ..pi../sup -/) as well as non-identical (..pi../sup +/, ..pi../sup -/) pion pair correlations. A momentum dependence is observed in the interference correlation function at small momentum differences. Previously only the identical pion interference correlations have been reported. In this thesis, the non-identical pion pair correlation is also studied. The momentum dependence is also new. For (..pi../sup -/,..pi../sup +/) and (..pi../sup -/,..pi../sup -/) pairs, the enhancement is due mostly to pions with mom/sup */>600 MeV/c. However for (..pi../sup +/, ..pi../sup +/) pairs, the peak is due primarily to pions with mom<200 MeV/c. Using the method of Kopylov and Podgoretsky the identical pion source region is determined to be 4.1 +/- 2.3 fermis. Also the influence on the final state correlations by the Bose statistics, Coulomb, and nuclear forces is observed. The possibility of using the (..pi../sup +/,..pi../sup -/) pion pair correlations to examine the pions produced in the quark-gluon perturbative vacuum of high-energy nucleus-nucleus collisions is suggested.

  11. 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

    2015-03-04

    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.

  12. 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

    2015-07-07

    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.

  13. 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.

  14. Vacuum ultraviolet photoionization mass spectra and cross-sections for volatile organic compounds at 10.5 eV.

    PubMed

    Kanno, Nozomu; Tonokura, Kenichi

    2007-08-01

    Vacuum ultraviolet single-photon ionization time-of-flight mass spectrometry (VUV-SPI-TOFMS) has been applied to the detection of volatile organic compounds (VOCs), including aromatic, chlorinated, and oxygenated compounds. Photoionization mass spectra of 23 VOCs were measured using SPI-TOFMS at 10.5 eV (118 nm). The limits of detection of VOCs using SPI-TOFMS at 10.5 eV were estimated to be a few ppbv. The mass spectra of 20 VOCs exhibit only the parent ion and its isotopes' signals. The ionization processes of the VOCs were discussed on the basis of the reaction enthalpies predicted by the quantum chemical calculations. Absolute photoionization cross-sections for 23 VOCs, including 12 newly measured VOCs, at 10.5 eV were determined in comparison to the reported absolute photoionization cross-section of NO.

  15. 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.

  16. Prenatal and postnatal manganese teeth levels and neurodevelopment at 7, 9, and 10.5 years in the CHAMACOS cohort

    PubMed Central

    Mora, Ana M.; Arora, Manish; Harley, Kim G.; Kogut, Katherine; Parra, Kimberly; Hernández-Bonilla, David; Gunier, Robert B.; Bradman, Asa; Smith, Donald R.; Eskenazi, Brenda

    2015-01-01

    Background Numerous cross-sectional studies of school-age children have observed that exposure to manganese (Mn) adversely affects neurodevelopment. However, few prospective studies have looked at the effects of both prenatal and postnatal Mn exposure on child neurodevelopment. Methods We measured Mn levels in prenatal and early postnatal dentine of shed teeth and examined their association with behavior, cognition, memory, and motor functioning in 248 children aged 7, 9, and/or 10.5 years living near agricultural fields treated with Mn-containing fungicides in California. We used generalized linear models and generalized additive models to test for linear and nonlinear associations, and generalized estimating equation models to assess longitudinal effects. Results We observed that higher prenatal and early postnatal Mn levels in dentine of deciduous teeth were adversely associated with behavioral outcomes, namely internalizing, externalizing, and hyperactivity problems, in boys and girls at 7 and 10.5 years. In contrast, higher Mn levels in prenatal and postnatal dentine were associated with better memory abilities at ages 9 and 10.5, and better cognitive and motor outcomes at ages 7 and 10.5 years, among boys only. Higher prenatal dentine Mn levels were also associated with poorer visuospatial memory outcomes at 9 years and worse cognitive scores at 7 and 10.5 years in children with higher prenatal lead levels (≥0.8 μg/dL). All these associations were linear and were consistent with findings from longitudinal analyses. Conclusions We observed that higher prenatal and early postnatal Mn levels measured in dentine of deciduous teeth, a novel biomarker that provides reliable information on the developmental timing of exposures to Mn, were associated with poorer behavioral outcomes in school-age boys and girls and better motor function, memory, and/or cognitive abilities in school-age boys. Additional research is needed to understand the inconsistencies in the

  17. Apparatus to measure the vapor pressure of slowly decomposing compounds from 1 Pa to 10(5) Pa.

    PubMed

    Berg, Robert F

    2015-11-01

    This article describes an apparatus and method for measuring vapor pressures in the range from 1 Pa to 10(5) Pa. Its three distinctive elements are : (1) the static pressure measurements were made with only a small temperature difference between the vapor and the condensed phase, (2) the sample was degassed in situ, and (3) the temperature range extended up to 200 °C. The apparatus was designed to measure metal-organic precursors, which often are toxic, pyrophoric, or unstable. Vapor pressures are presented for naphthalene, ferrocene, diethyl phthalate, and TEMAH (tetrakisethylmethylaminohafnium). Also presented are data for the temperature-dependent decomposition rate of TEMAH.

  18. Enhanced low-temperature CO oxidation on a stepped platinum surface for oxygen pressures above 10(-5) Torr.

    PubMed

    Lewis, Henry D; Burnett, Daniel J; Gabelnick, Aaron M; Fischer, Daniel A; Gland, John L

    2005-11-24

    The rate of CO oxidation has been characterized on the stepped Pt(411) surface for oxygen pressures up to 0.002 Torr, over the 100-1000 K temperature range. CO oxidation was characterized using both temperature-programmed reaction spectroscopy (TPRS) and in situ soft X-ray fluorescence yield near-edge spectroscopy (FYNES). New understanding of the important role surface defects play in accelerating CO oxidation for oxygen pressure above 10(-5) Torr is presented in this paper for the first time. For saturated monolayers of CO, the oxidation rate increases and the activation energy decreases significantly for oxygen pressures above 10(-5) Torr. This enhanced CO oxidation rate is caused by a change in the rate-limiting step to a surface reaction limited process above 10(-5) Torr oxygen from a CO desorption limited process at lower oxygen pressure. For example, in oxygen pressures above 0.002 Torr, CO(2) formation begins at 275 K even for the CO saturated monolayer, which is well below the 350 K onset temperature for CO desorption. Isothermal kinetic measurements in flowing oxygen for this stepped surface indicate that activation energies and preexponential factors depend strongly on oxygen pressure, a factor that has not previously been considered critical for CO oxidation on platinum. As oxygen pressure is increased from 10(-6) to 0.002 Torr, the oxidation activation energies for the saturated CO monolayer decrease from 24.1 to 13.5 kcal/mol for reaction over the 0.95-0.90 ML CO coverage range. This dramatic decrease in activation energy is associated with a simple increase in oxygen pressure from 10(-5) to 10(-3) Torr. Activation energies as low as 7.8 kcal/mol were observed for oxidation of an initially saturated CO layer reacting over the 0.4-0.25 ML coverage range in oxygen pressure of 0.002 Torr. These dramatic changes in reaction mechanism with oxygen pressure for stepped surfaces are consistent with mechanistic models involving transient low activation energy

  19. 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.

  20. Monitoring stress related velocity variation in concrete with a 2 x 10(-5) relative resolution using diffuse ultrasound.

    PubMed

    Larose, Eric; Hall, Stephen

    2009-04-01

    Ultrasonic waves propagating in solids have stress-dependent velocities. The relation between stress (or strain) and velocity forms the basis of non-linear acoustics. In homogeneous solids, conventional time-of-flight techniques have measured this dependence with spectacular precision. In heterogeneous media such as concrete, the direct (ballistic) wave around 500 kHz is strongly attenuated and conventional techniques are less efficient. In this manuscript, the effect of weak stress changes on the late arrivals constituting the acoustic diffuse coda is tracked. A resolution of 2 x 10(-5) in relative velocity change is attained which corresponds to a sensitivity to stress change of better than 50 kPa. Therefore, the technique described here provides an original way to measure the non-linear parameter with stress variations on the order of tens of kPa.

  1. Design note of an air-cooled 2 ft x 2 ft x 10. 5 ft long muon spoiler

    SciTech Connect

    Visser, A.; Pathiyil, J.

    1988-01-06

    This note describes the construction of a muon spoiler (magnetized steel assembly) with a cross section of 2 ft by 2 ft and a length of 10.5 ft. Two such spoilers are operated in series at an average field of about 15 kGauss, from one 100 ADC, 40 V power supply. The purpose of the spoilers is to prevent muons from easily escaping beyond the muon laboratory experimental area by bending them down so that they have to pass through more earth. The spoilers reduce the muon dose rate beyond the experimental area by about a factor of 15 to 20. These types of spoilers are not precision devices. They were inexpensive to build from scrap materials using rough flame cutting methods. It took about 14 days to fabricate them.

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

    PubMed

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

    2016-08-22

    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.

  4. A trapped-ion-based quantum byte with 10(-5) next-neighbour cross-talk.

    PubMed

    Piltz, C; Sriarunothai, T; Varón, A F; Wunderlich, C

    2014-08-19

    The addressing of a particular qubit within a quantum register is a key pre-requisite for scalable quantum computing. In general, executing a quantum gate with a single qubit, or a subset of qubits, affects the quantum states of all other qubits. This reduced fidelity of the whole-quantum register could prevent the application of quantum error correction protocols and thus preclude scalability. Here we demonstrate addressing of individual qubits within a quantum byte (eight qubits) and measure the error induced in all non-addressed qubits (cross-talk) associated with the application of single-qubit gates. The quantum byte is implemented using microwave-driven hyperfine qubits of (171)Yb(+) ions confined in a Paul trap augmented with a magnetic gradient field. The measured cross-talk is on the order of 10(-5) and therefore below the threshold commonly agreed sufficient to efficiently realize fault-tolerant quantum computing. Hence, our results demonstrate how this threshold can be overcome with respect to cross-talk.

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

    NASA Astrophysics Data System (ADS)

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

    1990-08-01

    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.

  6. 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.

  7. 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.

  8. High-pressure synthesis, structure, and photoluminescence of a new KSbO3-type bismuth germanate Bi3Ge3O10.5.

    PubMed

    Cheng, Jinguang; Rettie, Alexander J E; Suchomel, Matthew R; Zhou, Haidong; Yan, Jiaqiang; Song, Jie; Marshall, Luke G; Larregola, Sebastian A; Zhou, Jianshi; Goodenough, John B

    2013-02-18

    A new Bi(3)Ge(3)O(10.5) compound has been synthesized under high pressure, P = 7 GPa, and 700 °C. Instead of the pyrochlore that is normally stabilized under high pressure, the Bi(3)Ge(3)O(10.5) crystallizes in a KSbO(3)-ype crystal structure. The crystal structure has been refined by the Rietveld method from synchrotron X-ray diffraction data. Moreover, we have also characterized the Bi(3)Ge(3)O(10.5) by X-ray photoelectron spectroscopy, photoluminescence, and specific heat.

  9. 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.

  10. 10/20, 10/10, and 10/5 systems revisited: their validity as relative head-surface-based positioning systems.

    PubMed

    Jurcak, Valer; Tsuzuki, Daisuke; Dan, Ippeita

    2007-02-15

    With the advent of multi-channel EEG hardware systems and the concurrent development of topographic and tomographic signal source localization methods, the international 10/20 system, a standard system for electrode positioning with 21 electrodes, was extended to higher density electrode settings such as 10/10 and 10/5 systems, allowing more than 300 electrode positions. However, their effectiveness as relative head-surface-based positioning systems has not been examined. We previously developed a virtual 10/20 measurement algorithm that can analyze any structural MR head and brain image. Extending this method to the virtual 10/10 and 10/5 measurement algorithms, we analyzed the MR images of 17 healthy subjects. The acquired scalp positions of the 10/10 and 10/5 systems were normalized to the Montreal Neurological Institute (MNI) stereotactic coordinates and their spatial variability was assessed. We described and examined the effects of spatial variability due to the selection of positioning systems and landmark placement strategies. As long as a detailed rule for a particular system was provided, it yielded precise landmark positions on the scalp. Moreover, we evaluated the effective spatial resolution of 329 scalp landmark positions of the 10/5 system for multi-subject studies. As long as a detailed rule for landmark setting was provided, 241 scalp positions could be set effectively when there was no overlapping of two neighboring positions. Importantly, 10/10 positions could be well separated on a scalp without overlapping. This study presents a referential framework for establishing the effective spatial resolutions of 10/20, 10/10, and 10/5 systems as relative head-surface-based positioning systems.

  11. 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.

  12. Heat transfer investigation of two Langley Research Center delta wing configurations at a Mach number of 10.5, volume 1

    NASA Technical Reports Server (NTRS)

    Eaves, R. H.; Buchanan, T. D.; Warmbrod, J. D.; Johnson, C. B.

    1972-01-01

    Heat transfer tests for two delta wing configurations were conducted in the hypervelocity wind tunnel. The 24-inch long models were tested at a Mach number of approximately 10.5 and at angles of attack of 20, 40, and 60 degrees over a length Reynolds number range from 5 million to 23 million on 4 May to 4 June 1971. Heat transfer results were obtained from model surface heat gage measurements and thermographic phosphor paint.

  13. Cation movement and phase transitions in KTP isostructures; X-ray study of sodium-doped KTP at 10.5 K.

    PubMed

    Norberg, Stefan T; Sobolev, Alexander N; Streltsov, Victor A

    2003-06-01

    An accurate structure model of sodium-doped potassium titanyl phosphate, (Na(0.114)K(0.886))K(TiO)(2)(PO(4))(2), has been determined at 10.5 K by single-crystal X-ray diffraction. In addition to the low-temperature data, X-ray intensities have been collected at room temperature. When the temperature was decreased from room temperature to 10.5 K, both potassium cations moved 0.033 (2) A along the c-axis, i.e. in the polar direction within the rigid Ti-O-P network. This alkaline metal ion displacement can be related to the Abrahams-Jamieson-Kurtz T(C) criteria for oxygen framework ferroelectrics. Potassium titanyl phosphate (KTP) is a well known material for second harmonic generation (SHG), and the influence of sodium dopant on the TiO(6) octahedral geometry and SHG is discussed. The material studied crystallizes in the space group Pna2(1) with Z = 4, a = 12.7919 (5), b = 6.3798 (4), c = 10.5880 (7) A, V = 864.08 (9) A(3), T = 10.5 (3) K and R = 0.023.

  14. 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.

  15. Space shuttle: Heat transfer investigation of the McDonnell-Douglas delta wing orbiter at a nominal Mach number of 10.5

    NASA Technical Reports Server (NTRS)

    Eaves, R. H.; Buchanan, T. D.

    1972-01-01

    Heat transfer tests for the delta wing orbiter were conducted in a hypervelocity wind tunnel. A 1.1 percent scale model was tested at a Mach number of approximately 10.5 over an angle of attack range from 10 to 60 degrees over a length Reynolds number range from 5 times 10 to the 6th power to 24 times 10 to the 6th power. Heat transfer results were obtained from model surface heat gage measurements and thermographic phosphor paint. Limited pressure measurements were obtained.

  16. Synthesis and photoluminescence control of Ca10.5-1.5xLax(PO4)7:Eu2+ phosphors by aliovalent cation substitution

    NASA Astrophysics Data System (ADS)

    Fan, Yanting; Tang, Miao; Qiu, Zhongxian; Zhang, Jilin; Yu, Liping; Li, Chengzhi; Lian, Shixun; Zhou, Wenli

    2017-02-01

    A range of Ca10.5-1.5xLax(PO4)7:Eu2+phosphors were synthesized by high temperature solid state method. Subsequently we studied the crystal structures and luminescent properties through X-ray diffraction, photoluminescence and photoluminescence excitation, diffuse reflection spectra, Raman spectra and decay curves systematically. Based on the special crystal structure ofβ-Ca3(PO4)2:Eu2+, its emission undergoes a variation from violet-blue to cyan through introducing La3+. The substitution of La3+ for Ca2+ could form some cation vacancies in Ca(4) sites according to the scheme 3Ca2+= 2La3++ □ due to the different ion valence, which compels Eu2+ to migrate from Ca(4) site to other sites. Additionally, the formation of the cation vacancies can further reduce the thermal stability of phosphors.

  17. Bilateral perisylvian polymicrogyria, periventricular nodular heterotopia, and left ventricular noncompaction in a girl with 10.5-11.1 Mb terminal deletion of 1p36.

    PubMed

    Saito, Shoji; Kawamura, Rie; Kosho, Tomoki; Shimizu, Takashi; Aoyama, Koki; Koike, Kenichi; Wada, Takahito; Matsumoto, Naomichi; Kato, Mitsuhiro; Wakui, Keiko; Fukushima, Yoshimitsu

    2008-11-15

    Monosomy 1p36 is a common subtelomeric microdeletion syndrome, characterized by craniofacial dysmorphisms, developmental delay, mental retardation, hypotonia, epilepsy, cardiovascular complications, and hearing impairment; deleted regions have been mapped within 10.0 Mb from the telomere in most documented cases. We report on a girl with a 10.5-11.1 Mb terminal deletion of 1p36 shown by fluorescence in situ hybridization (FISH). She had three distinct structural abnormalities: bilateral perisylvian polymicrogyria, periventricular nodular heterotopia, and left ventricular noncompaction. She died in early infancy with intractable epilepsy, progressive congestive heart failure and pulmonary hypertension. To date, this is the first case with monosomy 1p36, complicated by this combination of manifestations; she is also the first who had possibly a simple terminal deletion of 1p36 and died in early infancy. An atypically large deletion in this patient might be the basis for the development of these features and the severe clinical course.

  18. Hyperfine polarization and its normal gradient coefficient of (87)Rb atoms in the vicinity (approximately 10(-5) cm) of coated and uncoated Pyrex glass surfaces.

    PubMed

    Zhao, K; Wu, Z

    2003-09-12

    We have made regionally specific measurement of the hyperfine polarization of 87Rb atoms in the vicinity ( approximately 10(-5) cm) of coated and uncoated Pyrex glass surfaces. We find that the polarization near an uncoated surface decreases rapidly with decreasing distance from the surface whereas for a silicone-coated surface the polarization is independent of the distance from the surface. We have also determined the normal gradient coefficient micro (S.I) of the hyperfine polarization in uncoated cells. In a representative uncoated cell, at a Rb density 7.35 x 10(13) cm(-3) and a pump beam intensity 1.3 W/cm(2), we find micro(S.I)=24+/-7 microm(-1).

  19. Femoral impaction bone allografting with an Exeter cemented collarless, polished, tapered stem in revision hip replacement: a mean follow-up of 10.5 years.

    PubMed

    Wraighte, P J; Howard, P W

    2008-08-01

    Femoral impaction bone allografting has been developed as a means of restoring bone stock in revision total hip replacement. We report the results of 75 consecutive patients (75 hips) with a mean age of 68 years (35 to 87) who underwent impaction grafting using the Exeter collarless, polished, tapered femoral stem between 1992 and 1998. The mean follow-up period was 10.5 years (6.3 to 14.1). The median pre-operative bone defect score was 3 (interquartile range (IQR) 2 to 3) using the Endo-Klinik classification. The median subsidence at one year post-operatively was 2 mm (IQR 1 to 3). At the final review the median Harris hip score was 80.6 (IQR 67.6 to 88.9) and the median subsidence 2 mm (IQR 1 to 4). Incorporation of the allograft into trabecular bone and secondary remodelling were noted radiologically at the final follow-up in 87% (393 of 452 zones) and 40% (181 of 452 zones), respectively. Subsidence of the Exeter stem correlated with the pre-operative Endo-Klinik bone loss score (p = 0.037). The degree of subsidence at one year had a strong association with long-term subsidence (p < 0.001). There was a significant correlation between previous revision surgery and a poor Harris Hip score (p = 0.028), and those who had undergone previous revision surgery for infection had a higher risk of complications (p = 0.048). Survivorship at 10.5 years with any further femoral operation as the end-point was 92% (95% confidence interval 82 to 97).

  20. 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.

  1. 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

  2. Characterization of neutron and photon sources from a 10.5 MeV proton beam on [18O] enriched water

    NASA Astrophysics Data System (ADS)

    Miller, L. F.; Townsend, L. W.; Alvord, C. W.

    2001-07-01

    The production of F-18 from a 10.5 MeV proton beam on oxygen-18 results in significant yields of neutrons and photons. In order to optimize personnel shielding that satisfies regulatory requirements, it is essential that both the intensity of both neutrons and of photons be determined as a function of energy and angle, which was accomplished by combining results from measurements and from calculations. Energy dependence for neutrons was estimated as a function by unfolding Bonner ball measurements, a hyper-pure germanium detector was used to obtain measurements of the photon spectra, and a well established computer program was used to obtain the calculated values. The radiation intensity was determined from calibrated survey meters for neutrons and for photons. The energy and angular dependence obtained from measurements and calculations agree within the uncertainty of the measurements, but calculated results, scaled by measurements, were used for input to radiation shield design studies. The neutron yield is sufficiently high to be of interest for several applications.

  3. 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.

  4. On the physics of the bimodal coherent dynamics of the turbulent horseshoe vortex at Re=1.16x10^5

    NASA Astrophysics Data System (ADS)

    Paik, Joongcheol; Escauriaza, Cristian; Sotiropoulos, Fotis

    2006-11-01

    Due to the strong adverse pressure gradients, the boundary layer approaching a wall-mounted obstacle undergoes a three-dimensional separation with horseshoe vortices which wrap around the obstacle like necklace. Devenport and Simpson (J Fluid Mech., Vol. 210, P. 23 1990) reported the large scale unsteady bimodal nature of the horseshoe vortex system in the leading edge region of a wing at Re=1.16x10^5 which switches aperiodically from one mode to another at time intervals and accounts for turbulent energy production and turbulent stresses an order of magnitude higher than those from conventional shear mechanism in the upstream boundary layer. We carried out detached eddy simulations of the flow past a wing experimentally investigated by Devenport and Simpson and for the first time numerically confirmed the experimental finding of the bimodal velocity probability phenomenon in the horseshoe vortex region. Detailed quantitative comparisons with the measurements and analysis of the 3D nature of large scale coherent vortical structures in the wing-body junction flow will be present in the presentation.

  5. 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.

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

    PubMed

    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.

  7. 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.

  8. An experimental setup for high resolution 10.5 eV laser-based angle-resolved photoelectron spectroscopy using a time-of-flight electron analyzer.

    PubMed

    Berntsen, M H; Götberg, O; Tjernberg, O

    2011-09-01

    We present an experimental setup for laser-based angle-resolved time-of-flight photoemission. Using a picosecond pulsed laser, photons of energy 10.5 eV are generated through higher harmonic generation in xenon. The high repetition rate of the light source, variable between 0.2 and 8 MHz, enables high photoelectron count rates and short acquisition times. By using a time-of-flight analyzer with angle-resolving capabilities, electrons emitted from the sample within a circular cone of up to ±15° can be collected. Hence, simultaneous acquisition of photoemission data for a complete area of the Brillouin zone is possible. The current photon energy enables bulk sensitive measurements, high angular resolution, and the resulting covered momentum space is large enough to enclose the entire Brillouin zone in cuprate high-T(c) superconductors. Fermi edge measurements on polycrystalline Au shows an energy resolution better than 5 meV. Data from a test measurement of the Au(111) surface state are presented along with measurements of the Fermi surface of the high-T(c) superconductor Bi(2)Sr(2)CaCu(2)O(8 + δ) (Bi2212).

  9. 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

    2013-06-07

    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'.

  10. 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.

  11. 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... Technology Administration. (10) Maritime Administration. General Counsel means the General Counsel of...

  12. 46 CFR 59.10-5 - Cracks.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING REPAIRS TO BOILERS, PRESSURE VESSELS AND... particle, dye penetrant, or other acceptable test method. When the reverse side of the weld is accessible... weld cannot be back chipped because the reverse side is inaccessible, a backing strip or other...

  13. 49 CFR 10.5 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... including, but not limited to, education, financial transactions, medical history, and criminal or... determination about an identifiable individual, except as provided by section 8 of title 13, United States...

  14. 44 CFR 10.5 - Responsibilities.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... required, or whether a finding of no significant impact shall be prepared; (2) Review all proposed changes... their respective organizational units; (2) Prepare and process environmental assessments and...) Review all proposed changes or additions to the list of categorical exclusions; (3) Review all...

  15. 46 CFR 56.10-5 - Pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... found from Table 56.60-1(a). (3) Copper-nickel alloys may be used for water and steam service within the... specifically permitted by this part. (6) Aluminum-alloy pipe or tube along with similar junction equipment...

  16. 46 CFR 56.10-5 - Pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... found from Table 56.60-1(a). (3) Copper-nickel alloys may be used for water and steam service within the... specifically permitted by this part. (6) Aluminum-alloy pipe or tube along with similar junction equipment...

  17. 46 CFR 56.10-5 - Pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... found from table 56.60-1(a). (3) Copper-nickel alloys may be used for water and steam service within the... specifically permitted by this part. (6) Aluminum-alloy pipe or tube along with similar junction equipment...

  18. 46 CFR 2.10-5 - Exemptions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... vessel's use for fundraising activities without regard to the age of the participants aboard the vessel, provided revenues raised are for the operation and maintenance of the vessel and that such fundraising activities do not exceed one day of fundraising for each month of the vessel's operating season. (d)...

  19. 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... specifically permitted by this part. (6) Aluminum-alloy pipe or tube along with similar junction equipment...

  20. 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... specifically permitted by this part. (6) Aluminum-alloy pipe or tube along with similar junction equipment...

  1. 46 CFR 59.10-5 - Cracks.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... under this subpart shall be excavated to sound metal by grinding, flame or arc gouging or chipping out... deposited metal and the resultant groove welded to obtain a sound weld having complete penetration. When the... maintained by controlled temperatures. The degree of preheat shall be determined by the rules listed...

  2. 46 CFR 59.10-5 - Cracks.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... under this subpart shall be excavated to sound metal by grinding, flame or arc gouging or chipping out... deposited metal and the resultant groove welded to obtain a sound weld having complete penetration. When the... maintained by controlled temperatures. The degree of preheat shall be determined by the rules listed...

  3. 32 CFR 10.5 - Construction.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 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...

  4. 32 CFR 10.5 - Construction.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 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...

  5. 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...

  6. 32 CFR 10.5 - Construction.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 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...

  7. 32 CFR 10.5 - Construction.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 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...

  8. Light-Soaking-Free Inverted Polymer Solar Cells with an Efficiency of 10.5% by Compositional and Surface Modifications to a Low-Temperature-Processed TiO2 Electron-Transport Layer.

    PubMed

    Yan, Yu; Cai, Feilong; Yang, Liyan; Li, Jinghai; Zhang, Yiwei; Qin, Fei; Xiong, Chuanxi; Zhou, Yinhua; Lidzey, David G; Wang, Tao

    2017-01-01

    Compositional modification and surface treatments of a TiO2 film prepared by a low-temperature route are carried out by a new promising method. Inverted polymer solar cells incorporating the post-treated TiO2 :TOPD electron-transport layer achieve the highest efficiency of 10.5%, and more importantly, eliminate the light-soaking problem that is commonly observed in metal-oxide-based inverted polymer solar cells.

  9. Hyperfine-structure study of the 3d10 5p 2P3/2 level of neutral copper using pulsed level-crossing spectroscopy at short laser wavelengths

    NASA Astrophysics Data System (ADS)

    Bengtsson, J.; Larsson, J.; Svanberg, S.; Wahlstrom, C.-G.

    1990-01-01

    A hyperfine-structure study of the strongly perturbed 3d10 5p 2P3/2 state of neutral copper was performed using pulsed level-crossing spectroscopy. Excitation was accomplished at the short wavelength of 202 nm, where intense laser pulses were obtained using frequency tripling of dye laser radiation. For Cu-63, a = 61.7(9) MHz, b = 4.9(7) MHz, and tau = 25,5(10) ns were obtained for the magnetic dipole and the electric quadrupoles interaction constants and the lifetime, respectively. A comparison with theoretical calculations based on the multiconfiguration Hartree-Fock method is made. A discussion of the usefulness of level-crossing, quantum-beat, and radio-frequency techniques for high-resolution spectroscopy at wavelengths in the UV and vacuum-UV region is presented.

  10. 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.

  11. Ultrasound backscatter microscopy image-guided intraventricular gene delivery at murine embryonic age 9.5 and 10.5 produces distinct transgene expression patterns at the adult stage.

    PubMed

    Jang, Jiwon; Ahn, Jyhyun; Lee, Nayeon; Kim, Seong-Tae; Kweon, Dae-Hyuk; Cho, Jae Youl; Park, Kye Won; Kim, Sunyoung; Yoon, Keejung

    2013-01-01

    In utero injection of a retroviral vector into the embryonic telencephalon aided by ultrasound backscatter microscopy permits introduction of a gene of interest at an early stage of development. In this study, we compared the tissue distribution of gene expression in adult mice injected with retroviral vectors at different embryonic ages in utero. Following ultrasound image-guided gene delivery (UIGD) into the embryonic telencephalon, adult mice were subjected to whole-body luciferase imaging and immunohistochemical analysis at 6 weeks and 1 year postinjection. Luciferase activity was observed in a wide range of tissues in animals injected at embryonic age 9.5 (E9.5), whereas animals injected at E10.5 showed brain-localized reporter gene expression. These results suggest that mouse embryonic brain creates a closed and impermeable structure around E10. Therefore, by injecting a transgene before or after E10, transgene expression can be manipulated to be local or systemic. Our results also provide information that widens the applicability of UIGD beyond neuroscience studies.

  12. Poly[[dodeca-aqua-bis-(μ(3)-pyridine-2,6-dicarboxyl-ato)tetra-kis-(μ(2)-pyridine-2,6-dicarboxyl-ato)tri-calciumdieuropium(III)] 10.5-hydrate].

    PubMed

    Shi, Fengjuan; Deng, Jiguang; Dai, Hongxing

    2012-05-01

    In the title compound, {[Ca(3)Eu(2)(C(7)H(3)NO(4))(6)(H(2)O)(12)]·10.5H(2)O}(n), the Eu(III) ion is nine-coordinated by three tridentate pyridine-2,6-dicarboxyl-ate (PDA) ligands, forming a [Eu(PDA)(3)](3-) building block. The Ca(2+) ions adopt two types of coordination geometries. One Ca(2+) ion, lying on a twofold rotation axis, is eight-coordinated by four carboxyl-ate O atoms from four PDA ligands and four water mol-ecules, and the other two Ca(2+) ions, each lying on an inversion center, are six-coordinated by two carboxyl-ate O atoms from two PDA ligands and four water mol-ecules. The carboxyl-ate groups bridge the Eu(III) and Ca(2+) ions into a three-dimensional porous framework, with channels extending along [010] and [001] in which lattice water mol-ecules are located. Two of the lattice water mol-ecules are disordered over two sets of sites with equal occupancy and one water mol-ecule is 0.25-occupied. Numerous O-H⋯O hydrogen bonds involving the water mol-ecules and carboxyl-ate O atoms are present.

  13. Replacement of amino acid sequence features of a- and c-subunits of ATP synthases of Alkaliphilic Bacillus with the Bacillus consensus sequence results in defective oxidative phosphorylation and non-fermentative growth at pH 10.5.

    PubMed

    Wang, ZhenXiong; Hicks, David B; Guffanti, Arthur A; Baldwin, Katisha; Krulwich, Terry Ann

    2004-06-18

    Mitchell's (Mitchell, P. (1961) Nature 191, 144-148) chemiosmotic model of energy coupling posits a bulk electrochemical proton gradient (Deltap) as the sole driving force for proton-coupled ATP synthesis via oxidative phosphorylation (OXPHOS) and for other bioenergetic work. Two properties of proton-coupled OXPHOS by alkaliphilic Bacillus species pose a challenge to this tenet: robust ATP synthesis at pH 10.5 that does not correlate with the magnitude of the Deltap and the failure of artificially imposed potentials to substitute for respiration-generated potentials in energizing ATP synthesis at high pH (Krulwich, T. (1995) Mol. Microbiol. 15, 403-410). Here we show that these properties, in alkaliphilic Bacillus pseudofirmus OF4, depend upon alkaliphile-specific features in the proton pathway through the a- and c-subunits of ATP synthase. Site-directed changes were made in six such features to the corresponding sequence in Bacillus megaterium, which reflects the consensus sequence for non-alkaliphilic Bacillus. Five of the six single mutants assembled an active ATPase/ATP synthase, and four of these mutants exhibited a specific defect in non-fermentative growth at high pH. Most of these mutants lost the ability to generate the high phosphorylation potentials at low bulk Deltap that are characteristic of alkaliphiles. The aLys(180) and aGly(212) residues that are predicted to be in the proton uptake pathway of the a-subunit were specifically implicated in pH-dependent restriction of proton flux through the ATP synthase to and from the bulk phase. The evidence included greatly enhanced ATP synthesis in response to an artificially imposed potential at high pH. The findings demonstrate that the ATP synthase of extreme alkaliphiles has special features that are required for non-fermentative growth and OXPHOS at high pH.

  14. Identification of similarity of skeletal structures in the range 10-5 cm - 1023 cm and the probable role of skeletal assemblies of carbon nanotube-like dust in the large-scale structure of the Universe

    NASA Astrophysics Data System (ADS)

    Kukushkin, A. B.; Rantsev-Kartinov, V. A.

    The role of the dust in astrophysics is analyzed from viewpoint of the hypothesis [1] (and respective proof-of-concept studies [2]) for the self-assembling of a fractal dust in laboratory electric discharges. The presence of skeletal structures of the same distinctive topology (namely, tubules and cartwheels, and their simple combinations) in the range 10-5cm - 1023cm, and a trend toward self-similarity (i.e. assembling of bigger structures from similar smaller ones), are found [3]. These evidences come from the electron micrography of dust deposits in tokamak (10-6cm - 10-3cm) [4], the images of plasma taken in laboratory electric discharges -- tokamaks, Z-pinches, plasma focus and vacuum spark (10-2cm - 10 cm) [2], hail particles (1cm - 10cm), the images of tornado (103cm - 105cm) and of a wide class of objects in space (1011cm - 1023 cm), including the solar coronal mass ejection, supernova remnants, and some galaxies [3]. The similarity of, and a trend toward self-similarity in, these skeletal structures (especially, cartwheels as the structures of essentially non-hydrodynamic nature) suggest all them to possess, similarly to skeletons in the particles of dust and hail, a fractal condensed matter of particular topology of the fractal. Specifically, this matter may be assembled from nanotubular blocks in a way similar to that in the skeletons found [4] in the submicron dust particles. An analysis of the redshift surveys of galaxies and quasars suggests the possibility to draw the above similarity up to 1026cm. This hints at the presence of a baryonic cold dark skeleton (BCDS) of the Universe [5]. The hypothesis of BCDS is shown to have no conflict with major cosmological facts (Hubble expansion and cosmic microwave background's isotropy). REFERENCES: [1] Fusion Energy 1998 (IAEA, Vienna, 1999), Vol. 3, p. 1131. [2] Advances in Plasma Phys. Research, Vol. 2 (Ed. F. Gerard, Nova Science Publishers, New York, 2002), pp. 1-22. [3] Phys. Lett. A 306, 175 (2002). [4

  15. Results from the ARTEMIS DISK Global Antifungal Surveillance Study, 1997 to 2007: a 10.5-year analysis of susceptibilities of Candida Species to fluconazole and voriconazole as determined by CLSI standardized disk diffusion.

    PubMed

    Pfaller, M A; Diekema, D J; Gibbs, D L; Newell, V A; Ellis, D; Tullio, V; Rodloff, A; Fu, W; Ling, T A

    2010-04-01

    Fluconazole in vitro susceptibility test results for 256,882 isolates of Candida spp. were collected from 142 sites in 41 countries from June 1997 to December 2007. Data were collected for 197,619 isolates tested with voriconazole from 2001 to 2007. A total of 31 different species of Candida were isolated. Increased rates of isolation of the common non-albicans species C. glabrata (10.2% to 11.7%), C. tropicalis (5.4% to 8.0%), and C. parapsilosis (4.8% to 5.6%) were noted when the time periods 1997 to 2000 and 2005 to 2007 were compared. Investigators tested clinical isolates of Candida spp. by the CLSI M44-A disk diffusion method. Overall, 90.2% of Candida isolates tested were susceptible (S) to fluconazole; however, 13 of 31 species identified exhibited decreased susceptibility (<75% S), similar to that seen with the resistant (R) species C. glabrata and C. krusei. Among 197,619 isolates of Candida spp. tested against voriconazole, 95.0% were S and 3% were R. About 30% of fluconazole-R isolates of C. albicans, C. glabrata, C. tropicalis, C. rugosa, C. lipolytica, C. pelliculosa, C. apicola, C. haemulonii, C. humicola, C. lambica, and C. ciferrii remained S to voriconazole. An increase in fluconazole resistance over time was seen with C. parapsilosis, C. guilliermondii, C. lusitaniae, C. sake, and C. pelliculosa. Among the emerging fluconazole-R species were C. guilliermondii (11.4% R), C. inconspicua (53.2% R), C. rugosa (41.8% R), and C. norvegensis (40.7% R). The rates of isolation of C. rugosa, C. inconspicua, and C. norvegensis increased by 5- to 10-fold over the 10.5-year study period. C. guilliermondii and C. rugosa were most prominent in Latin America, whereas C. inconspicua and C. norvegensis were most common in Eastern European countries. This survey identifies several less-common species of Candida with decreased susceptibility to azoles. These organisms may pose a future threat to optimal antifungal therapy and underscore the importance of prompt and

  16. 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.

  17. Pervasive and Persistent Large-Volume, low delta 18O Silicic Magma Generation at the Yellowstone Hotspot, 12.7-10.5 Ma: Ion Microprobe Analyses of Zircon in the Cougar Point Tuff

    NASA Astrophysics Data System (ADS)

    Cathey, H. E.; Nash, B. P.; Valley, J. W.; Kita, N.; Ushikubo, T.; Spicuzza, M.

    2007-12-01

    High precision analyses of oxygen isotopes measured by ion microprobe in cores and rims of 111 zircon crystals from the voluminous Cougar Point Tuff (CPT) of the Bruneau-Jarbidge eruptive center in southern Idaho, USA, confirm the presence of the largest low δ18O silicic volcanic province yet discovered (c.f. Boroughs, 2005). These data provide an unprecedented, high resolution view into details of large-volume magma generation and source materials at a major eruptive center of the Yellowstone hotspot. The CPT consists of at least ten members of high-temperature (800-1000 °C) ignimbrites erupted from 12.7-10.5 Ma with a collective eruptive volume estimated at ≥ 7000 km3. Analyses of zircon were performed on the University of Wisconsin Cameca IMS-1280 using a spot diameter of 10 microns, with an average analytical precision for δ18O on the KIM5 standard of 0.3‰ (2 s.d.). Core and rim spot locations were carefully selected using cathodoluminescence and secondary electron imaging to evaluate zoning patterns, identify core locations and avoid inclusions. All but two zircon grains display rims that are depleted in 18O, and ~60 % of crystals display core-rim zonation of 0.5 to 7.4‰. The total range of δ18OVSMOW in cores of the 109 zircons with low δ18O rims is from -1.8 to 6.4 ‰; rims of these zircons range from -3.1 to 3.3 ‰. Within individual units, cores of zoned zircons are generally more variable than rims and vary over a minimum of 1.5 ‰ (Unit IX) and up to 8.2 ‰ (Unit VII). Rims vary 0.4 (Unit IX) to 5.2‰ (Unit XII). Our data indicate that the vast majority of zircons (96%) grew in low δ18O crustal melts, and that multiple discrete lowδ18O sources were involved in magma generation for most eruptive units. Whereas zircon cores display the most variable compositions, rims in several units converge to a more restricted range of δ18O values, although all units but IX show rim variability > 0.8 ‰. The presence of multiple discrete magma

  18. Tip-AGB stellar evolution in the presence of a pulsating, dust-induced ``superwind"

    NASA Astrophysics Data System (ADS)

    Schröder, K.-P.; Winters, J. M.; Sedlmayr, E.

    1999-09-01

    We present selected ``superwind" mass-loss histories and the related tip-AGB stellar evolution models, which have been computed according to the characteristics of a dust-induced, carbon-rich wind, and which include several recent improvements as compared to Schröder et al. (1998). We discuss the (initial) stellar mass-range of 1 to 2.5 Msun, with a nearly solar composition (X=0.28, Y=0.70, Z=0.02). In each time-step, mass-loss rates are used, which are consistent with the actual stellar parameters, and which are based on our pulsating, dust-induced wind models for carbon-rich stars (Fleischer et al. 1992), including a detailed and consistent treatment of dust formation, radiative transfer and radiative wind acceleration. The resulting ``superwind" mass-loss rates reach 2 to 3* 10(-5) Msun yr(-1) . For this reason, they become an influential factor of tip-AGB stellar evolution - but also vice versa, since our mass-loss rates vary strongly with effective temperature (dot {M} ~ T_eff(-8) (roughly), see Arndt et al. 1997), reflecting the temperature sensitivity of the dust formation process on a macroscopic scale. With all tip-AGB models of an initial stellar mass Mi >~ 1.3 Msun we find superwinds with a total mass outflow of 0.26 to >~ 0.55 Msun during their final 3* 10(4) yrs, just as required for PN-formation. Furthermore, a thermal pulse leads to a very short (100 to 200 yrs) interruption of the ``superwind" of these models. A critical (Eddington-like) luminosity Lc is required for the radiation driven wind models, which our evolution models fail to reach for Mi <~ 1.1 Msun. With slightly larger stellar masses, L_tAGB is near Lc and thermal pulses can trigger very short ``superwind" bursts, as already pointed out by Schröder et al. (1998). We find good agreement between our improved models and the mass-loss characteristics of the thin CO shells found by Olofsson et al. (1990, 1993, 1996, 1998) around some carbon-rich Mira stars.

  19. Hubble Space Telescope Spectroscopic Evidence for a 1 X 10 9 Msun Black Hole in NGC 4594

    NASA Astrophysics Data System (ADS)

    Kormendy, John; Bender, Ralf; Ajhar, Edward A.; Dressler, Alan; Faber, S. M.; Gebhardt, Karl; Grillmair, Carl; Lauer, Tod R.; Richstone, Douglas; Tremaine, Scott

    1996-12-01

    The discovery by Kormendy of a M• ~= 109 Msolar massive dark object (MDO) in NGC 4594 is confirmed with higher resolution spectroscopy from the Canada-France-Hawaii Telescope (CFHT) and the Hubble Space Telescope (HST). CFHT measurements with the Subarcsecond Imaging Spectrograph improve the resolution from sigma * = 0."40 to 0."27 Gaussian dispersion radius of the point-spread function (PSF). The apparent central velocity dispersion rises from sigma = 250 +/- 7 km s-1 to sigma = 286 +/- 7 km s-1. As observed with the COSTAR-corrected HST, the Faint Object Spectrograph, and a 0."21 aperture, sigma = 321 +/- 7 km s-1 is still higher, and the central rotation curve is very steep. The highest-M• published dynamical model fits the new observations reasonably well when "observed" at HST resolution. The spatial resolution has now improved by a factor of ~5 since the discovery measurements, and the case for a black hole (BH) has strengthened correspondingly. We confirm that NGC 4594 has a Seyfert spectrum; H alpha is ~5200 km s-1 wide at zero intensity. However, gas velocities are lower than the circular velocities implied by the stars, so they cannot be used to test the BH case in NGC 4594. The gas may be in a ring, or it may be associated with patchy dust. HST images with the Wide Field and Planetary Camera 2 show dust at some aperture positions. NGC 4594 appears to have a bright point nucleus. However, the central absorption-line strengths are low, consistent with dilution by enough nonthermal light to explain the "nucleus." There is no evidence for a distinct nuclear star cluster. NGC 4594 is similar to M87, which also has a nonthermal nuclear source, and not to M31 and NGC 3115, which have quiescent BHs and nuclear star clusters.

  20. 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).

  1. Pd-Catalyzed Cyclocarbonylation of 2-(2-Bromoaryl)indoles with CO as a C1 Source: Selective Access to 6 H-Isoindolo[2,1-a]indol-6-ones and Indeno[1,2-b]indol-10(5 H)-ones.

    PubMed

    Guo, Shenghai; Tao, Li; Wang, Fang; Fan, Xuesen

    2016-11-07

    A highly efficient and regioselective synthetic route to 6 H-isoindolo[2,1-a]indol-6-ones and indeno[1,2-b]indol-10(5 H)-ones through the Pd-catalyzed cyclocarbonylation of 2-(2-bromoaryl)indoles under atmospheric CO pressure has been achieved. Notably, the regioselectivity of the reaction was exclusively dependent on the structural characteristics of the indole substrates. With N-unsubstituted indoles as the starting materials, the reaction afforded 6H-isoindolo[2,1-a]indol-6-ones in good-to-excellent yields. On the other hand, with N-substituted indoles as the substrates, the reaction gave indeno[1,2-b]indol-10(5 H)-ones in a highly regioselective manner.

  2. 15 CFR 10.5 - Development of a recommended standard.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... the committee, the balloting shall be either by roll call or by signed written ballot conducted by the... of all members of the committee. (c) Any member of the committee casting a negative ballot shall...

  3. 15 CFR 10.5 - Development of a recommended standard.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... the committee, the balloting shall be either by roll call or by signed written ballot conducted by the... of all members of the committee. (c) Any member of the committee casting a negative ballot shall...

  4. 15 CFR 10.5 - Development of a recommended standard.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... the committee, the balloting shall be either by roll call or by signed written ballot conducted by the... of all members of the committee. (c) Any member of the committee casting a negative ballot shall...

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

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... the committee, the balloting shall be either by roll call or by signed written ballot conducted by the... of all members of the committee. (c) Any member of the committee casting a negative ballot shall...

  6. US EPA, Pesticides, Label, SEGMENT HERBICIDE, 10/5/2010

    EPA Pesticide Factsheets

    2011-04-13

    ... [fl~~=~p:~~I~~~~~E-~~~~r~~:"S~~::~r~~".~7:::·~I;::J Acacia, knife leaf Acacia cultriformis ... Purpleleaf, Bailey acacia Redwood, coast ...

  7. 46 CFR 95.10-5 - Fire pumps.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... nozzle may be used. The pump may be hand operated and the length of hose shall be sufficient to assure... pump. Branch lines connected to the fire main for purposes other than fire and deck wash shall be...

  8. 46 CFR 76.10-5 - Fire pumps.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... approximately 50 p. s. i. Where one or both of these outlets is a 11/2-inch siamese fitting, both branches of the siamese fitting at each such outlet shall be utilized for the purpose of this requirements....

  9. ICD-10: 5 steps to a comprehensive financial impact analysis.

    PubMed

    Levy, Brian

    2013-03-01

    To ensure a successful transition to ICD-IO, hospitals should: Investigate industry guidelines. Analyze claims using mapping tools. Measure the potential impact on payment. Practice ICD-10 coding in collaboration with payers. Study cost reduction opportunities.

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

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... area boundary. If it is necessary to construct the magazine in proximity to these areas, a cofferdam... seas. The location selected shall not impair access to accommodations or other spaces necessary to...

  11. 46 CFR 194.10-5 - Type and location.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... area boundary. If it is necessary to construct the magazine in proximity to these areas, a cofferdam... seas. The location selected shall not impair access to accommodations or other spaces necessary to...

  12. 46 CFR 194.10-5 - Type and location.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... area boundary. If it is necessary to construct the magazine in proximity to these areas, a cofferdam... seas. The location selected shall not impair access to accommodations or other spaces necessary to...

  13. 46 CFR 76.10-5 - Fire pumps.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... capable of delivering water simultaneously from the two highest outlets at a Pitot tube pressure of... conditions, are not capable of developing a pressure exceeding this amount. (e) Fire pumps shall be fitted with a pressure gauge on the discharge side of the pumps. (f) Fire pumps may be used for other...

  14. 46 CFR 76.10-5 - Fire pumps.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... capable of delivering water simultaneously from the two highest outlets at a Pitot tube pressure of... conditions, are not capable of developing a pressure exceeding this amount. (e) Fire pumps shall be fitted with a pressure gauge on the discharge side of the pumps. (f) Fire pumps may be used for other...

  15. 46 CFR 76.10-5 - Fire pumps.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... capable of delivering water simultaneously from the two highest outlets at a Pitot tube pressure of... conditions, are not capable of developing a pressure exceeding this amount. (e) Fire pumps shall be fitted with a pressure gauge on the discharge side of the pumps. (f) Fire pumps may be used for other...

  16. 46 CFR 76.10-5 - Fire pumps.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... International voyage Other Hose and hydrant size, inches Nozzle orifice size, inches Length of hose, feet 100 2...) Fire pumps shall be fitted on the discharge side with relief valves set to relieve at 25 p. s. i. in... with a pressure gauge on the discharge side of the pumps. (f) Fire pumps may be used for other...

  17. 46 CFR 95.10-5 - Fire pumps.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... pumps Hose and hydrant size, inches Nozzle orifice size, inches Length of hose feet 100 1 1 1 11/2 1 1/2... be only 35 p.s.i. (d) Fire pumps shall be fitted on the discharge side with relief valves set to... pumps shall be fitted with a pressure gage on the discharge side of the pumps. (f) Fire pumps may...

  18. Photoevaporated Flows from H II Regions

    NASA Astrophysics Data System (ADS)

    Lizano, Susana; Canto, Jorge; Garay, Guido; Hollenbach, David

    1996-09-01

    We model the dynamics of a fast, isothermal ionized stellar wind loaded with mass injected from photoevaporated globules surrounding the massive star. The effect of the mass injection is to produce a density profile such that the ionization front can be trapped for 105 yr, depending on the physical characteristics of the neutral globules inside the H II region. We find that for neutral globules with sizes Rg 0.01 pc, masses of Mg ˜ 1 Msun, and number densities Ng ˜ 2x 104 pc-3, thought to be representative of globules in regions of massive star formation, the implied mean density and size of the mass-loaded regions of ionized gas are about 103-104 cm-3 and about 0.1 pc, respectively, similar to those of compact H II regions. Dust absorption of ionizing photons is important and decreases the densities of the mass-loaded winds with respect to their dust-free counterparts. Also, mass-loaded winds with dust evolve more slowly, since the dusty globules survive for longer times than the dust-free ones. Our models predict ionized flows with mass flow rates of Mdot ˜ 10-5 to 10-4 Msun yr-1. These ionized flows could be studied in radio recombination lines. Assuming Ng does not decline sharply with distance to the central star, the ionized flow will recombine after the characteristic "Strömgren" radius rS at which the ionizing photon rate goes to zero. Therefore, after this radius a neutral flow will accelerate adiabatically to a terminal velocity of VHI ˜ 40 km s-1. Neutral flows of this type could be searched for in the neutral hydrogen line at 21 cm in absorption against the continuum of the compact H II regions.

  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. 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.

  1. New search strategy for high z intervening absorbers: GRB 021004, a pilot study

    NASA Astrophysics Data System (ADS)

    Vreeswijk, P. M.; Møller, P.; Fynbo, J. P. U.

    2003-10-01

    We present near-infrared narrow- and broad-band imaging of the field of GRB 021004, performed with ISAAC on the UT1 of the ESO Very Large Telescope. The narrow-band filters were chosen to match prominent emission lines at the redshift of the absorption-line systems found against the early-time afterglow of GRB 021004: [O Iii] at z=1.38 and Hα at z=1.60, respectively. For the z=1.38 system we find an emission-line source at an impact parameter of 16'', which is somewhat larger than the typical impact parameters of a sample of Mg Ii absorbers at redshifts around unity. Assuming that this tentative redshift-identification is correct, the star formation rate of the galaxy is 13+/-2 Msun yr-1. Our study reaches star-formation rate limits (5sigma ) of 5.7 Msun yr-1 at z=1.38, and 7.7 Msun yr-1 at z=1.60. These limits correspond to a depth of roughly 0.13 L*. Any galaxy counterpart of the absorbers nearer to the line of sight either has to be fainter than this limit or not be an emission-line source. Based on observations collected at the European Southern Observatory, Chile; proposal No. 270.A-5016.

  2. 46 CFR 54.10-5 - Maximum allowable working pressure (reproduces UG-98).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... adjusted for any difference in static head that may exist between the part considered and the top of the... internal or external pressure, including the static head hereon, as determined by the rules and formulas...

  3. 46 CFR 54.10-5 - Maximum allowable working pressure (reproduces UG-98).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... vessel. (See Appendix 3 of section VIII of the ASME Boiler and Pressure Vessel Code (incorporated by... section VIII of the ASME Boiler and Pressure Vessel Code, together with the effect of any combination of loadings listed in UG-22 of section VIII of the ASME Boiler and Pressure Vessel Code (see 46 CFR...

  4. 46 CFR 31.10-5 - Inspection of new tank vessels-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Officer in Charge, Marine Inspection, of the district in which the vessel is to be built; and one set... determine whether it has been built in accordance with the approved plans and specifications, and, if so, a... accepted by the Coast Guard as evidence of the structural efficiency of the hull and reliability...

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

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Officer in Charge, Marine Inspection, of the district in which the vessel is to be built; and one set... determine whether it has been built in accordance with the approved plans and specifications, and, if so, a... accepted by the Coast Guard as evidence of the structural efficiency of the hull and reliability...

  6. 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...

  7. 46 CFR 31.10-5 - Inspection of new tank vessels-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... home office is located at 321 West 44th Street, New York, NY 10036, on the Internet at http://www.icgb... accepted by the Coast Guard as evidence of the structural efficiency of the hull and reliability...

  8. 46 CFR 39.10-5 - Incorporation by reference-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Companies International Marine Forum (OCIMF), 15th Floor, 96 Victoria Street, London SWIE 5JW, England International Safety Guide for Oil Tankers and Terminals, Third Edition, 1988 39.30-1 ... International Electrotechnical Commission (IEC), Bureau Central de la Commission Electrotechnique...

  9. 46 CFR 39.10-5 - Incorporation by reference-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Companies International Marine Forum (OCIMF), 15th Floor, 96 Victoria Street, London SWIE 5JW, England International Safety Guide for Oil Tankers and Terminals, Third Edition, 1988 39.30-1 ... International Electrotechnical Commission (IEC), Bureau Central de la Commission Electrotechnique...

  10. 46 CFR 39.10-5 - Incorporation by reference-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Companies International Marine Forum (OCIMF), 15th Floor, 96 Victoria Street, London SWIE 5JW, England International Safety Guide for Oil Tankers and Terminals, Third Edition, 1988 39.30-1 ... International Electrotechnical Commission (IEC), Bureau Central de la Commission Electrotechnique...

  11. 46 CFR 54.10-5 - Maximum allowable working pressure (reproduces UG-98).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... section VIII of the ASME Boiler and Pressure Vessel Code, together with the effect of any combination of... operating temperature, using for each temperature the applicable allowable stress value. Note: Table...

  12. 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…

  13. 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…

  14. 46 CFR 12.10-5 - Examination and demonstration of ability.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... liferafts, the handling of lifeboats under oars and sails, including questions relative to the proper... out the orders incident to launching lifeboats, and the use of the boat's sail, and to row. (d)...

  15. 46 CFR 12.10-5 - Examination and demonstration of ability.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... liferafts, the handling of lifeboats under oars and sails, including questions relative to the proper... out the orders incident to launching lifeboats, and the use of the boat's sail, and to row. (d)...

  16. 46 CFR 12.10-5 - Examination and demonstration of ability.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... liferafts, the handling of lifeboats under oars and sails, including questions relative to the proper... out the orders incident to launching lifeboats, and the use of the boat's sail, and to row. (d)...

  17. Millwright Apprenticeship. Related Training Modules. 10.1-10.5 Combustion.

    ERIC Educational Resources Information Center

    Lane Community Coll., Eugene, OR.

    This packet, part of the instructional materials for the Oregon apprenticeship program for millwright training, contains five modules covering combustion. The modules provide information on the following topics: the combustion process, types of fuel, air and fuel gases, heat transfer, and combustion in wood. Each module consists of a goal,…

  18. 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...

  19. 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...

  20. 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.

  1. A 10.5 cm ultrasound link for deep implanted medical devices.

    PubMed

    Mazzilli, Francesco; Lafon, Cyril; Dehollain, Catherine

    2014-10-01

    A study on ultrasound link for wireless energy transmission dedicated to deeply implanted medical devices is presented. The selection of the frequency to avoid biological side effects (e.g., cavitations), the choice of the power amplifier to drive the external transducers and the design of the rectifier to maximize the energy extraction from the implanted transducer are described in details. The link efficiency is characterized in water using a phantom material for a transmitter-receiver distance of 105 mm, transducers active area of 30 mm × 96 mm and 5 mm × 10 mm, respectively, and a system efficiency of 1.6% is measured.

  2. 46 CFR 34.10-5 - Fire pumps-T/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... international voyage, each required fire pump, while delivering water through the fire main system at a pressure...— Minimum number of pumps Powerful streams of water per pump Minimum hydrant and hose size (inches) Exterior... at least 2 fire pumps. 3 From hydrants having greatest pressure drop between fire-pump(s) and...

  3. 46 CFR 34.10-5 - Fire pumps-T/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... international voyage, each required fire pump, while delivering water through the fire main system at a pressure...— Minimum number of pumps Powerful streams of water per pump Minimum hydrant and hose size (inches) Exterior... at least 2 fire pumps. 3 From hydrants having greatest pressure drop between fire-pump(s) and...

  4. 20 CFR 10.5 - What definitions apply to the regulations in this subchapter?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... anatomic or functional abnormality or loss. A permanent impairment is any such abnormality or loss after... her license to practice medicine has been suspended or revoked by a State licensing or...

  5. 20 CFR 10.5 - What definitions apply to these regulations?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) Impairment means any anatomic or functional abnormality or loss. A permanent impairment is any such... during the period for which his or her license to practice medicine has been suspended or revoked by...

  6. 20 CFR 10.5 - What definitions apply to the regulations in this subchapter?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... anatomic or functional abnormality or loss. A permanent impairment is any such abnormality or loss after... her license to practice medicine has been suspended or revoked by a State licensing or...

  7. 20 CFR 10.5 - What definitions apply to these regulations?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... the individual enters school to continue his or her education, and each successive 12-month period in... entitlement to benefits as determined by OWCP under the FECA and the procedures described in this part. (k... level means: (i) The 12-month period beginning the month after the individual graduates from high...

  8. 20 CFR 10.5 - What definitions apply to the regulations in this subchapter?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... this subchapter means Compensation as defined by the FECA at 5 U.S.C. 8101(12), which is the money OWCP... as determined by OWCP under the FECA and the procedures described in this part. (k) FECA means the... beyond the high school level means: (i) The 12-month period beginning the month after the...

  9. Structural, Magnetic, and Microwave Properties of BaFe10.5Mn1.5O19 Thin Films

    SciTech Connect

    Geiler, A.; Yang, A; Zuo, X; Yoon, S; Chen, Y; Harris, V; Vittoria, C

    2008-01-01

    Epitaxial manganese substituted M-type barium ferrite thin films are deposited by alternating target laser ablation deposition (ATLAD) of BaFe{sub 2}O{sub 4}, Fe{sub 2}O{sub 3}, and MnFe{sub 2}O{sub 4} targets. The crystal structure and the epitaxy of the films are investigated by X-ray diffraction. Surface morphology is studied by atomic force microscopy. Magnetic properties of the films are characterized by vibrating sample magnetometry and magnetization as a function of temperature measurements. Ferromagnetic resonance (FMR) measurements are utilized to study the dynamic properties of the films. Possible mechanisms for main FMR linewidth broadening as a result of Mn substitution, such as increased conductivity and the presence of Jahn-Teller effect associated with octahedrally coordinated Mn{sup 3+} cations, are briefly discussed. Extended absorption X-ray fine structure measurements are performed to determine the cation distribution in the hexagonal unit cell. The observed 15-20% increase in saturation magnetization at 4 K and 50 K increase in the Neel temperature in comparison to bulk reference values are attributed to differences in cation distribution as a result of atomic scale deposition by the ATLAD technique.

  10. 25 CFR 10.5 - Where can I find the policies and standards for the administration, operation, services, and...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... administration, operation, services, and physical plant/construction of Indian country detention, community... Indian country detention, community residential, and holding facilities? The Bureau of Indian Affairs... the BIA's policies, procedures, and standards for detention and holding programs in Indian...

  11. 25 CFR 10.5 - Where can I find the policies and standards for the administration, operation, services, and...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... administration, operation, services, and physical plant/construction of Indian country detention, community... Indian country detention, community residential, and holding facilities? The Bureau of Indian Affairs... the BIA's policies, procedures, and standards for detention and holding programs in Indian...

  12. 25 CFR 10.5 - Where can I find the policies and standards for the administration, operation, services, and...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... administration, operation, services, and physical plant/construction of Indian country detention, community... Indian country detention, community residential, and holding facilities? The Bureau of Indian Affairs... the BIA's policies, procedures, and standards for detention and holding programs in Indian...

  13. 25 CFR 10.5 - Where can I find the policies and standards for the administration, operation, services, and...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... administration, operation, services, and physical plant/construction of Indian country detention, community... Indian country detention, community residential, and holding facilities? The Bureau of Indian Affairs... the BIA's policies, procedures, and standards for detention and holding programs in Indian...

  14. 25 CFR 10.5 - Where can I find the policies and standards for the administration, operation, services, and...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... administration, operation, services, and physical plant/construction of Indian country detention, community... Indian country detention, community residential, and holding facilities? The Bureau of Indian Affairs... the BIA's policies, procedures, and standards for detention and holding programs in Indian...

  15. 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.

  16. 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

    ... must also be in normal health for his/her age and pass a physical examination prescribed by the... survivor annuity to a spouse will remain valid in the event the marriage is dissolved and the spouse... shall terminate on the last day of the month before death or remarriage before attaining age 60. If...

  17. 22 CFR 19.10-5 - Reduced annuity with additional survivor annuity to spouse or former spouse.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... must also be in normal health for his/her age and pass a physical examination prescribed by the... survivor annuity to a spouse will remain valid in the event the marriage is dissolved and the spouse... shall terminate on the last day of the month before death or remarriage before attaining age 60. If...

  18. 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

    ... 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 granted. Temporary recognition will be granted only in unusual circumstances and it will not be granted, in...

  19. 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

    ... 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 as... preparer should be granted. Temporary recognition will be granted only in unusual circumstances and it...

  20. 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

    ... 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 as... preparer should be granted. Temporary recognition will be granted only in unusual circumstances and it...

  1. 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

    ... 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 a determination as to whether enrollment to practice should be granted. Temporary recognition will be granted...

  2. 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

    ... 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 as... preparer should be granted. Temporary recognition will be granted only in unusual circumstances and it...

  3. Allosteric FBPase inhibitors gain 10(5) times in potency when simultaneously binding two neighboring AMP sites.

    PubMed

    Hebeisen, Paul; Kuhn, Bernd; Kohler, Philipp; Gubler, Marcel; Huber, Walter; Kitas, Eric; Schott, Brigitte; Benz, Jörg; Joseph, Catherine; Ruf, Armin

    2008-08-15

    Human fructose-1,6-bisphosphatase (FBPase, EC 3.1.3.11) is a key gluconeogenic enzyme, responsible for the hydrolysis of fructose-1,6-bisphosphate to fructose-6-phosphate, and thus presents an opportunity for the development of novel therapeutics focused on lowering the hepatic glucose production in type 2 diabetics. In its active form FBPase exists as a homotetramer and is allosterically regulated by AMP. In an HTS campaign aromatic sulfonylureas have been identified as FBPase inhibitors mimicking AMP. By bridging two adjacent allosteric binding sites using two aromatic sulfonylureas as anchor units and covalently linking them, it was possible to obtain dual binding AMP site inhibitors that exhibit a strong inhibitory effect.

  4. The Merger Rate of Neutron Star Binaries in the Galaxy

    NASA Astrophysics Data System (ADS)

    Bailes, M.

    The major uncertainties in the merger rates of neutron star binaries are discussed, as well as a method of placing an upper limit on the binary neutron star population using simple ratios. We find that the merger rate is most unlikely to be greater than 10-5 yr -1 in our Galaxy, but is almost certainly greater than 10-7 yr-1. The prospects for hardening the merger rate in the near future are relatively bleak, with recent deep surveys failing to discover any systems capable of merging within a Hubble time. Other possible mergers involving black holes are briefly discussed.

  5. Nitrate and sediment fluxes from a California rangeland watershed.

    PubMed

    Lewis, David J; Singer, Michael J; Dahlgren, Randy A; Tate, Kenneth W

    2006-01-01

    Long-term water quality records for assessing natural variability, impact of management, and that guide regulatory processes to safeguard water resources are rare for California oak woodland rangelands. This study presents a 20-yr record (1981-2000) of nitrate-nitrogen (NO(3)-N) and suspended sediment export from a typical, grazed oak woodland watershed (103 ha) in the northern Sierra Nevada foothills of California. Mean annual precipitation over the 20-yr period was 734 mm yr(-1) (range 366-1205 mm yr(-1)). Mean annual stream flow was 353 mm y(-1) (range 87-848 mm yr(-1)). Average annual stream flow was 48.1 +/- 16% of precipitation. Mean annual NO(3)-N export was 1.6 kg ha(-1) yr(-1) (range 0.18-3.6 kg ha(-1) yr(-1)). Annual NO(3)-N export significantly (P < 0.05) increased with increasing annual stream flow and precipitation. Mean daily NO(3)-N export was 0.004 kg ha(-1) d(-1) (range 10(-5) to 0.55 kg ha(-1) d(-1)). Mean annual suspended sediment export was 198 kg ha(-1) yr(-1) (range 23-479 kg ha(-1) yr(-1)). There was a positive relationship (P < 0.05) between annual suspended sediment export, annual stream flow and precipitation. Mean daily suspended sediment export was 0.54 kg ha(-1) d(-1) (range 10(-4) to 155 kg ha(-1) d(-1)). Virtually no sediment was exported during the dry season. The large variation in daily and annual fluxes highlights the necessity of using long-term records to establish quantitative water quality targets for rangelands and demonstrates the difficulty of designing a water quality monitoring program for these ecosystems.

  6. X-Ray Spectroscopy of the O2 If* Star HD 93129A

    NASA Astrophysics Data System (ADS)

    Cohen, D. H.

    2012-12-01

    The O2 If* star, HD 93129A, is among the earliest in the Galaxy and has one of the strongest winds of any O star. In this paper, we show that its hard and strong X-ray emission can be understood in terms of the standard embedded wind shock paradigm for effectively single, hot, massive stars. Wind attenuation of the intrinsically soft X-ray emission is an important effect, which explains the hardness of the observed X-rays. We measure the degree of wind absorption in two different ways in order to derive a mass-loss rate of roughly 6 × 10-6 Msun; yr-1. This value is consistent with the observed Hα line if a clumping factor of fcl = 12 is assumed.

  7. New low-mass members of the Lupus 3 dark cloud: Further indications of pre-main-sequence evolution strongly affected by accretion

    NASA Astrophysics Data System (ADS)

    Comerón, F.; Fernández, M.; Baraffe, I.; Neuhäuser, R.; Kaas, A. A.

    2003-08-01

    A spectroscopic survey of a small area at the center of the Lupus 3 star-forming core has revealed four new mid-to-late M-type members, including a M7.5 brown dwarf. One of the new members, classified as M5, displays prominent forbidden lines and strong Hα emission (EW(Hα ) = 410 Å), in addition to other permitted lines, and its luminosity is far below that of other members of the region with similar or later spectral types. We estimate a mass accretion rate rate of ~ 1.4 x 10-9 Msun yr-1 for this object, although with uncertainties that do not exclude values as low as 10-10 Msun yr-1. Based on the Hα / [SII] ratio, the detection of HeI, and the CaII infrared triplet, we argue that most of the Hα emission is produced near the surface of the object, probably in accretion columns or at the base of jets, rather than in a low-density extended region. The strong emission-line spectrum superimposed on an unusually faint photospheric continuum thus seems to be a real, intrinsic feature rather than a result of the viewing geometry caused by an edge-on disk blocking the light from the central object. Other Lupus 3 late-type members also display noticeable underluminosity, all of them having EW(Hα ) > 100 Å as a result of the faint underlying continuum. We tentatively interpret these findings as evidence for the pre-main sequence evolution of objects with very low (possibly substellar) initial masses being significantly modified by accretion. Based on observations obtained at the European Southern Observatory using the Very Large Telescope in Cerro Paranal (program 67.C-0549(A)), the ESO New Technology Telescope in La Silla (program 69.B-0126(A)), and the 1.5 Danish telescope, also in La Silla (program 69.C-0423(B)).

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Structure and Stability of Steady Protostellar Accretion Flows - Part Two - Linear Stability Analysis

    NASA Astrophysics Data System (ADS)

    Balluch, M.

    1991-03-01

    Recent developments concerning spherically symmetric (1D-) numerical models of protostellar evolution show that steady protostellar accretion flows (resp. their shockfronts) may be unstable at least in the very early (Tscharnuter 1987a) and late stages (Balluch 1988) of accretion. A global, linear stability analysis of the structure of steady protostellar accretion flows with a shock discontinuity (Balluch 1990) is therefore presented to investigate such flows by different methods. Thereby three characteristic wave types, the radiation-, radiation diffusion- and acoustic modes were found. In the `ideal case' of a perfect gas law and constant opacity, the shockfront appears to be oscillatory unstable due to critical cooling as long as the mass flux rate is larger than a critical one of Mṡcrit = 10-6 Msun yr-1. In the `real case' with more realistic constitutive relations, an additional vibrational instability occurs due to the κ-mechanism in the outer layers of the core. This is shown to be the case in the whole range of core masses between 0.01 and 1 Msun, mass flow rates between 10-3 and 10-7 Msun yr-1 and different outer boundary conditions (corresponding to different states of the surrounding interstellar cloud). Analysing the first, outer protostellar cores before they get dynamically unstable due to H2-dissociation in their interiors, similar instabilities as mentioned above were found. Now the unstable κ-behaviour is due to dust instead of the deep ionisation zone as in the case of second, inner cores. According to the linear analysis, the instabilities should first appear in the velocity and the radiation flux in the settling zone. In the case of first, outer cores, these variations should be accompanied by an oscillation of the radiation flux in the region upstream from the shock up to r = 1014 cm. Sooner or later, the shockfront should oscillate in both cases too. These results are finally compared with the characteristics of the accretion shock

  13. 11-Methyl-12a-phenyl-9a,12a-dihydrophenanthro[9',10:5,6][1,4]dioxino[2,3-d]thiazole.

    PubMed

    Usman, Anwar; Razak, Ibrahim Abdul; Fun, Hoong Kun; Chantrapromma, Suchada; Zhang, Yan; Xu, Jian Hua

    2002-09-01

    In the title compound, C(24)H(17)NO(2)S, the dioxine and thiazoline rings are distorted from planarity towards a half-chair and an envelope conformation, respectively. The configurations of the dioxine ring, the thiazoline ring and the attached phenyl ring are conditioned by the sp(3) state of the two bridgehead C atoms. The phenanthrene system is nearly coplanar with the dioxine ring, while the attached phenyl ring is orthogonal to the thiazoline ring.

  14. 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.

  15. A Controlled Route to a Luminescent 3 d(10) -5 d(10) Sulfido Cluster Containing Unique AuCu2 (μ3 -S) Motifs.

    PubMed

    Polgar, Alexander M; Khadka, Chhatra B; Azizpoor Fard, Mahmood; Nikkel, Brian; O'Donnell, Terrence; Neumann, Tobias; Lahring, Kiana; Thompson, Kyle; Cadogan, Carolyn; Weigend, Florian; Corrigan, John F

    2016-12-19

    The first examples of gold(I) trimethylsilylchalcogenolate complexes were synthesized and their reactivity showcased in the preparation of a novel gold-copper-sulfur cluster [Au4 Cu4 S4 (dppm)2 ] (dppm=bis(diphenylphosphino)methane). The unprecedented structural chemistry of this compound gives rise to interesting optoelectronic properties, including long-lived orange luminescence in the solid state. Through time-dependent density functional theory calculations, this emission is shown to originate from ligand-to-metal charge transfer facilitated by Au⋅⋅⋅Cu metallophilic bonding.

  16. Phase diagram of the selenium-sulfur system in the pressure range 1 × 10-5-1 × 10-1 MPa

    NASA Astrophysics Data System (ADS)

    Volodin, V. N.; Burabaeva, N. M.; Trebukhov, S. A.; Ersaiynova, A. A.

    2016-11-01

    The partial pressures of the components in the saturated vapor of the Se-S system were determined and presented as the temperature-concentration dependences. Based on these data, the boundaries of the melt-vapor phase transition at atmospheric pressure and in vacuum (1350, 100, and 10 Pa) were calculated. A complete phase diagram was constructed, which included the vapor-liquid equilibrium fields at atmospheric and low pressures, whose boundaries allowed us to determine the behavior of sulfur and selenium during distillation separation.

  17. 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.

  18. Rotational energy transfer of SH(X2Π, v''=0, J''=0.5-10.5) by collision with Ar: Λ-doublet resolved transition propensity.

    PubMed

    Tsai, Po-Yu; Lin, King-Chuen

    2012-01-16

    The behavior of Λ-doublet resolved rotational energy transfer (RET) by Ar collisions within the SH(X(2)Π, v''=0) state is characterized. The matrix elements of terms in the interaction potential responsible for interference effects are calculated to explain the propensity rules for collision-induced transitions within and between spin-orbit manifolds. In this manner, the physical mechanisms responsible for the F(1)-F(1), F(2)-F(2), and F(1)-F(2) transitions may be reasonably identified. As collision energy increases, the propensity for collisional population of the final e or f level is replaced by the e/f-conserving propensity. Such a change in propensity rule can be predicted in terms of energy sudden approximation at high J limit for the pure Hund's case scheme.

  19. Developments in bile acid kinetic measurements using (13)C and (2)H: 10(5) times improved sensitivity during the last 40 years.

    PubMed

    Stellaard, Frans; Brufau, Gemma; Boverhof, Renze; Jonkers, Elles Zwanet; Boer, Theo; Kuipers, Folkert

    2009-12-01

    Bile acid kinetics involve the measurement of pool sizes and turnover rates of individual bile acids. The technique is based on isotope dilution and was first described in the 1950s using radioactive (14)C-labelled cholic acid (CA). It took until the 1970s before stable isotopes were introduced for this purpose ((13)C, (2)H) and isotope analysis methods were developed for CA and chenodeoxycholic acid (CDCA) applying gas chromatography/electron impact mass spectrometry. Until the 1980s, the isotope enrichment measurements were performed in bile samples aspirated from the duodenum. Thereafter, methodology became available allowing measurements to be performed in blood requiring at least 2 ml serum samples. Simultaneous measurement of kinetics of metabolically dependent CA and deoxycholic acid using (13)C and (2)H labels was introduced. Until the 1990s, this technique was only possible in adult humans due to the large sample sizes. Introduction of pentafluorobenzyl bromide derivatisation and electron capture negative ion mass spectrometry (GC/ECN-MS) reduced the sample volume to 50 microl serum. This allowed isotope abundance measurement of CA in rats and in mice. However, repetitive collection of 100 microl blood samples in mice is too invasive (collection via the orbita) and exhaustive. Therefore, the method development is now focussing on enhanced sensitivity and reduction of blank effects originating from the sample preparation. The final goal is to determine CA isotope enrichments in 20 microl mouse blood obtained from the tail vein. This paper shows the feasibility of reaching this goal.

  20. 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).

  1. 11-Methyl-12a-phenyl-9a,12a-dihydrophenanthro[9',10':5,6][1,4]dioxino[2,3-d]oxazole and 9a-(10-hydroxyphenanthren-9-yl)-11,12a-diphenyl-9a,12a-dihydrophenanthro[9',10':5,6][1,4]dioxino[2,3-d]oxazole.

    PubMed

    Usman, Anwar; Razak, Ibrahim Abdul; Fun, Hoong-Kun; Chantrapromma, Suchada; Zhang, Yan; Xu, Jian-Hua

    2002-08-01

    In the title compounds, C(24)H(17)NO(3), (I), and C(43)H(27)NO(5), (II), the dioxine ring is not planar and tends toward a boat conformation. The oxazoline ring adopts a twisted conformation in molecule (I) but is essentially planar in molecule (II). The configuration of the dioxine-oxazoline system is determined by the sp(3) state of the two shared atoms. The phenanthrene moiety is nearly coplanar with the dioxine ring, while the phenyl ring is perpendicular to the attached oxazole ring. The triclinic unit cell of (II) contains two crystallographically independent molecules related by a pseudo-inversion centre.

  2. The outburst of an embedded low-mass YSO in L1641

    NASA Astrophysics Data System (ADS)

    Caratti o Garatti, A.; Garcia Lopez, R.; Scholz, A.; Giannini, T.; Eislöffel, J.; Nisini, B.; Massi, F.; Antoniucci, S.; Ray, T. P.

    2011-02-01

    Context. Strong outbursts in very young and embedded protostars are rare and not yet fully understood. They are believed to originate from an increase in the mass accretion rate (dot{M}_acc) onto the source. Aims: We report the discovery of a strong outburst in a low-mass embedded young stellar object (YSO), namely 2MASS-J05424848-0816347 or [CTF93]216-2, as well as its photometric and spectroscopic follow-up. Methods: Using near- to mid-IR photometry and NIR low-resolution spectroscopy, we monitor the outburst, deriving its magnitude, duration, as well as the enhanced accretion luminosity and mass accretion rate. Results: [CTF93]216-2 increased in brightness by 4.6, 4.0, 3.8, and 1.9 mag in the J, H, Ks bands and at 24 μm, respectively, corresponding to an Lbol increase of 20 Lsun. Its early spectrum, probably taken soon after the outburst, displays a steep almost featureless continuum, with strong CO band heads and H2O broad-band absorption features, and Brγ line in emission. A later spectrum reveals more absorption features, allowing us to estimate Teff 3200 K, M_* 0.25 Msun, and dot{M}_acc 1.2 × 10-6 Msun yr-1. This makes it one of the lowest mass YSOs with a strong outburst so far discovered. Based on observations collected at the ESO/NTT (082.C-0264), at the REM telescope La Silla, Chile, and at the the Italian Telescopio Nazionale Galileo (TNG), operated on the island of La Palma by the Fundacion Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica).

  3. New clues on the contribution of Earth's volcanism to the global mercury cycle

    NASA Astrophysics Data System (ADS)

    Bagnato, E.; Aiuppa, A.; Parello, F.; Allard, P.; Shinohara, H.; Liuzzo, M.; Giudice, G.

    2011-07-01

    Active volcanoes are thought to be important contributors to the atmospheric mercury (Hg) budget, and this chemical element is one of the most harmful atmospheric pollutants, owing to its high toxicity and long residence time in ecosystems. There is, however, considerable uncertainty over the magnitude of the global volcanic Hg flux, since the existing data on volcanogenic Hg emissions are sparse and often ambiguous. In an attempt to extend the currently limited dataset on volcanogenic Hg emissions, we summarize the results of Hg flux measurements at seven active open-conduit volcanoes; Stromboli, Asama, Miyakejima, Montserrat, Ambrym, Yasur, and Nyiragongo.. Data from the dome-building Soufriere Hills volcano are also reported. Using our determined mercury to SO2 mass ratios in tandem with the simultaneously-determined SO2 emission rates, we estimate that the 7 volcanoes have Hg emission rates ranging from 0.2 to 18 t yr-1 (corresponding to a total Hg flux of ~41 t·yr-1). Based on our dataset and previous work, we propose that a Hg/SO2 plume ratio ~10-5 is best-representative of gas emissions from quiescent degassing volcanoes. Using this ratio, we infer a global volcanic Hg flux from persistent degassing of ~95 t·yr-1.

  4. Global-scale predictions of community and ecosystem properties from simple ecological theory.

    PubMed

    Jennings, Simon; Mélin, Frédéric; Blanchard, Julia L; Forster, Rodney M; Dulvy, Nicholas K; Wilson, Rod W

    2008-06-22

    We show how theoretical developments in macroecology, life-history theory and food-web ecology can be combined to formulate a simple model for predicting the potential biomass, production, size and trophic structure of consumer communities. The strength of our approach is that it uses remote sensing data to predict properties of consumer communities in environments that are challenging and expensive to sample directly. An application of the model to the marine environment on a global scale, using primary production and temperature estimates from satellite remote sensing as inputs, suggests that the global biomass of marine animals more than 10(-5) g wet weight is 2.62 x 10(9)t (=8.16 gm(-2) ocean) and production is 1.00 x 10(10) tyr-1 (31.15 gm(-2)yr(-1)). Based on the life-history theory, we propose and apply an approximation for distinguishing the relative contributions of different animal groups. Fish biomass and production, for example, are estimated as 8.99 x 10(8)t (2.80 gm(-2)) and 7.91 x 108 t yr(-1) (2.46 gm(2)yr(-1)respectively, and 50% of fish biomass is shown to occur in 17% of the total ocean area (8.22 gm(-2)). The analyses show that emerging ecological theory can be synthesized to set baselines for assessing human and climate impacts on global scales.

  5. 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.

  6. An inventory of particle and gaseous emissions from large aircraft thrust engine operations at an airport

    NASA Astrophysics Data System (ADS)

    Mazaheri, M.; Johnson, G. R.; Morawska, L.

    2011-07-01

    Published particle number emission factors for aircraft operations remain very sparse and so far such emissions have not been included in the International Civil Aviation Organization (ICAO) databases. This work addresses this gap in knowledge by utilizing recent progress in the quantification of aircraft particle emissions. Annual emissions of particle number (PN), particle mass (PM 2.5) and NO x throughout the aircraft landing and takeoff (LTO) cycles and ground running procedures (GRP) are presented for aircraft using Brisbane Airport BNE (domestic and international). The aircraft are grouped according to an airframe based classification system. The resulting data are then used to develop an emissions inventory for large aircraft thrust engine operations on the ground, during LTO cycles and GRP, at the Airport. Annual PN, PM 2.5 and NO x emissions from large aircraft operations during LTO cycles and GRP at BNE were 1.98 × 10 24 yr -1, 1.35 × 10 4 kg yr -1 and 8.13 × 10 5 kg yr -1, respectively. Results showed that LTO cycles contribute more than 97% of these annual emissions at BNE in comparison to GRP related emissions. Analysis of the LTO cycle contribution to the daily emissions showed that the contribution of the climbout mode is considerably higher than for other individual LTO operational modes. Emissions during aircraft departures were significantly higher than those during arrival operations, due to the higher aircraft engine emission rates during takeoff and climbout.

  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. Vertical Accretion Rates in Coastal Louisiana: A Review of the Scientific Literature

    DTIC Science & Technology

    2010-08-01

    2005; Mitsch and Gosselink 2007, Figure 1); however, this represents a decline of approximately 4,800 km2 of coastal habitat over the past century...in salinity can promote colonization by ERDC/EL TN-10-5 August 2010 4 more salt-tolerant plant species and convert freshwater marshes into...back-marsh (0.65 ± 0.18 to 0.90 ± 0.10 cm yr-1) habitats (Table 1). Feldspar methods showed similar results with greater variation in sediment

  9. 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

  10. 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

  11. The progression of symmetrical left ventricular hypertrophy in a 54-year-old man: a case report with a 10.5-year follow-up and literatures review.

    PubMed

    Yuan, Lianfang; Dai, Xuan

    2015-01-01

    Apical hypertrophic cardiomyopathy (AHCM) is a well-known clinical entity, which is characterized by LV apex hypertrophy and the giant negative T wave at ECG and a spade-like left ventricle. It is a uncommon morphologic variant of hypertrophic cardiomyopathy (HCM) and AHCM appears to be particularly common in Asia whose prevalence was 15% and 3% of all the HCM patients in Japan and USA, respectively. In this case, we present a dramatic progress from symmetrical left ventricular hypertrophy to AHCM with apical aneurysm.

  12. Results from the ARTEMIS DISK Global Antifungal Surveillance Study, 1997 to 2007: 10.5-year analysis of susceptibilities of noncandidal yeast species to fluconazole and voriconazole determined by CLSI standardized disk diffusion testing.

    PubMed

    Pfaller, M A; Diekema, D J; Gibbs, D L; Newell, V A; Bijie, H; Dzierzanowska, D; Klimko, N N; Letscher-Bru, V; Lisalova, M; Muehlethaler, K; Rennison, C; Zaidi, M

    2009-01-01

    Fluconazole in vitro susceptibility test results determined by the CLSI M44-A disk diffusion method for 11,240 isolates of noncandidal yeasts were collected from 134 study sites in 40 countries from June 1997 through December 2007. Data were collected for 8,717 yeast isolates tested with voriconazole from 2001 through 2007. A total of 22 different species/organism groups were isolated, of which Cryptococcus neoformans was the most common (31.2% of all isolates). Overall, Cryptococcus (32.9%), Saccharomyces (11.7%), Trichosporon (10.6%), and Rhodotorula (4.1%) were the most commonly identified genera. The overall percentages of isolates in each category (susceptible, susceptible dose dependent, and resistant) were 78.0%, 9.5%, and 12.5% and 92.7%, 2.3%, and 5.0% for fluconazole and voriconazole, respectively. Less than 30% of fluconazole-resistant isolates of Cryptococcus spp., Cryptococcus albidus, Cryptococcus laurentii, Trichosporon beigelii/Trichosporon cutaneum, Rhodotorula spp., Rhodotorula rubra/Rhodotorula mucilaginosa, and Rhodotorula glutinis remained susceptible to voriconazole. Emerging resistance to fluconazole was documented among isolates of C. neoformans from the Asia-Pacific, Africa/Middle East, and Latin American regions but not among isolates from Europe or North America. This survey documents the continuing broad spectrum of activity of voriconazole against opportunistic yeast pathogens but identifies several of the less common species with decreased azole susceptibility. These organisms may pose a future threat to optimal antifungal therapy and emphasize the importance of prompt and accurate species identification.

  13. 15-Hydroxy-ethyl-19-isopropyl-5,9-dimethyl-14,16-dioxo-15-aza-penta-cyclo-[10.5.2.0.0.0]nona-dec-18-ene-5-carboxylic acid.

    PubMed

    Xu, Xu; Song, Zhan-Qian; Shang, Shi-Bin; Wang, Hong-Xiao; Rao, Xiao-Ping

    2009-09-12

    The title compound, C(26)H(37)NO(5), which was synthesized from monoethano-lamine and maleopimaric acid, consists of two fused and unbridged cyclo-hexane rings. They form a trans ring junction with a chair conformation. The two methyl groups are in axial positions. In the crystal, inter-molecular O-H⋯O hydrogen bonds link adjacent mol-ecules into a layer structure. Two C-H⋯O interactions are also present.

  14. CFHTLenS: The Environmental Dependence of Galaxy Halo Masses from Weak Lensing

    NASA Astrophysics Data System (ADS)

    Gillis, Bryan; Hudson, M. J.; Erben, T.; Heymans, C.; Hildebrandt, H.; Hoekstra, H.; Kitching, T. D.; Mellier, Y.; Miller, L.; van Waerbeke, L.; Bonnett, C.; Coupon, J.; Fu, L.; Hilbert, S.; Rowe, B.; Schrabback, T.; Semboloni, E.; van Uitert, E.; Velander, M.; Cfhtlens Team

    2013-07-01

    We use weak gravitational lensing to analyse the dark matter halos around satellite galaxies in galaxy groups in the CFHTLenS dataset. This dataset is derived from the CFHTLS-Wide survey, and encompasses 154 sq. deg of high-quality shape data. Using the photometric redshifts, we divide the sample of lens galaxies with stellar masses in the range 10^9 Msun to 10^10.5 Msun into those likely to lie in high-density environments (HDE) and those likely to lie in low-density environments (LDE). Through comparison with galaxy catalogues extracted from the Millennium Simulation, we show that the sample of HDE galaxies should primarily 61%) consist of satellite galaxies in groups, while the sample of LDE galaxies should consist of mostly 87%) non-satellite (field and central) galaxies. Comparing the lensing signals around samples of HDE and LDE galaxies matched in stellar mass, the lensing signal around HDE galaxies clearly shows a positive contribution from their host groups on their lensing signals at radii of ~500--1000 kpc, the typical separation between satellites and group centres. More importantly, the subhalos of HDE galaxies are less massive than those around LDE galaxies by a factor 0.65 +/- 0.12, significant at the 2.9 sigma level. A natural explanation is that the halos of satellite galaxies are stripped through tidal effects in the group environment. Our results are consistent with a typical tidal truncation radius of ~40 kpc.

  15. 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.

  16. Belowground carbon turnover in a temperate ombrotrophic bog

    NASA Astrophysics Data System (ADS)

    Blodau, Christian; Roulet, Nigel T.; Heitmann, Tobias; Stewart, Heather; Beer, Julia; Lafleur, Peter; Moore, Tim R.

    2007-03-01

    To examine belowground carbon (C) turnover in peatlands, we measured fluxes of carbon dioxide (CO2) and methane (CH4) by chamber measurements, estimated respiration by in situ incubations of peat, and in situ production of dissolved carbon (CO2; CH4; and dissolved organic carbon, DOC) by pore water modeling at an ombrotrophic temperate bog. Ecosystem respiration (ER) averaged 205 mmol m-2 d-1 in summer and was related to temperature, but not water table position, and in situ rates of heterotrophic respiration in the unsaturated zone were also temperature-dependent, with Q10 = 5.0 - 6.4. In the saturated zone, concentrations of 0.1 - 2.5 mmol L-1 (CO2), 0 to 0.6 mmol L-1 (CH4), and <10 - 120 mg L-1 (DOC) were recorded. Turnover was dominated by DOC unrelated to respiration, which ranged from <0.5 to 7 mmol m-2 d-1 and amounted on average to < 1% of ER. Peat decomposition constants kd were 0.060 yr-1 to 0.034 yr-1 in the unsaturated and <0.002 yr-1 in the saturated zone. Monthly averages of CH4 fluxes ranged from 0 to 1.6 mmol m-2 d-1 and were higher than modeled diffusive fluxes when threshold concentrations for CH4 ebullition were recorded closer to the peatland surface. Our results suggest that the saturated zone is of little relevance to ER in this dry temperate bog and that mobilization of DOC is a potentially more relevant process. Temperature is a more important control on ER than water table position because most of the ER is generated close to the peatland surface. Concurrent, moderate increases in temperature and soil moisture are thus likely to increase losses of CO2 from ER and of CH4 from this type of peatland.

  17. streamgap-pepper: Effects of peppering streams with many small impacts

    NASA Astrophysics Data System (ADS)

    Bovy, Jo; Erkal, Denis; Sanders, Jason

    2017-02-01

    streamgap-pepper computes the effect of subhalo fly-bys on cold tidal streams based on the action-angle representation of streams. A line-of-parallel-angle approach is used to calculate the perturbed distribution function of a given stream segment by undoing the effect of all impacts. This approach allows one to compute the perturbed stream density and track in any coordinate system in minutes for realizations of the subhalo distribution down to 10^5 Msun, accounting for the stream's internal dispersion and overlapping impacts. This code uses galpy (ascl:1411.008) and the streampepperdf.py galpy extension, which implements the fast calculation of the perturbed stream structure.

  18. The Cretaceous Okhotsk-Chukotka Volcanic Belt (NE Russia): Geology, geochronology, magma output rates, and implications on the genesis of silicic LIPs

    NASA Astrophysics Data System (ADS)

    Tikhomirov, P. L.; Kalinina, E. A.; Moriguti, T.; Makishima, A.; Kobayashi, K.; Cherepanova, I. Yu.; Nakamura, E.

    2012-04-01

    The Cretaceous Okhotsk-Chukotka volcanic belt (OCVB) is a prominent subduction-related magmatic province, having the remarkably high proportion of silicic rocks (ca. 53% of the present-day crop area, and presumably over 70% of the total volcanic volume). Its estimated total extrusive volume ranges between 5.5 × 105 km3 (the most conservative estimate) and over 106 km3. This article presents a brief outline of the geology of OCVB, yet poorly described in international scientific literature, and results of a geochronological study on the northern part of the volcanic belt. On the base of new and published U-Pb and 40Ar/39Ar age determinations, a new chronological model is proposed. Our study indicates that the activity of the volcanic belt was highly discontinuous and comprised at least five main episodes at 106-98 Ma, 94-91 Ma, 89-87 Ma, 85.5-84 Ma, and 82-79 Ma. The new data allow a semi-quantitative estimate of the volcanic output rate for the observed part of the OCVB (area and volume approximately 105 km2 and 2.5 × 105 km3, respectively). The average extrusion rate for the entire lifetime of the volcanic belt ranges between 1.6 and 3.6 × 10- 5 km3yr- 1 km- 1, depending on the assumed average thickness of the volcanic pile; the optimal value is 2.6 × 10- 5 km3yr- 1 km- 1. Despite imprecise, such estimates infer the time-averaged volcanic productivity of the OCVB is similar to that of silicic LIPs and most active recent subduction-related volcanic areas of the Earth. However, the most extensive volcanic flare-ups at 89-87 and 85.5-84 Ma had higher rates of over 9.0 × 10- 5 km3yr- 1 km- 1. The main volumetric, temporal and compositional parameters of the OCVB are similar to those of silicic LIPs. This gives ground for discussion about the geodynamic setting of the latters, because the widely accepted definition of a LIP implies a strictly intraplate environment. Considering the genesis of the OCVB and other large provinces of silicic volcanism, we propose that

  19. X-ray selected Type-2 QSOs: ongoing star formation and obscured accretion.

    NASA Astrophysics Data System (ADS)

    Mainieri, Vincenzo; Cosmos Collaboration

    2009-09-01

    Although the fraction of obscured AGN is found to decrease with luminosity from several studies, a non-negligible population of obscured QSOs is still required by the X-ray background synthesis models. We present a large sample (121 objects) of X-ray selected Type-2 QSOs from the XMM-COSMOS survey: sources with high X-ray luminosity (LX>10^{44} erg s^{-1}) and heavy obscuration (NH>10^{22} cm^{-2}), as derived from a detailed X-ray spectral analysis (see Mainieri et al.,2007, ApJS, 172, 368) of the 1800 X-ray point-like sources in this survey. Few (˜5%) of the Type-2 QSOs are best fitted with a pure reflection model. We have performed optical spectroscopy for ˜ 30% of the sample and for the remaining sources we have derived accurate photometric redshifts. The redshift range covered is wide, 0.30.8).We compare the general properties of the host galaxies with the ongoing accretion in their nuclei. Morphology: using five non-parametric diagnostics (asymmetry, concentration, Gini coefficient, M20, ellipticity) we found that ˜10% of the Type-2 QSOs are in elliptical galaxies, ˜55% in disk galaxies and ˜35% in irregular galaxies. The majority of the irregular hosts can be described as undergoing merger activity or show tidal debris. Stellar masses have been derived from SED fitting to the observed photometry(from 0.3 to 4.5 micron) and star formation rates from the [OII] or Hα line fluxes. The majority (˜75%) of QSO-2 host galaxies have stellar masses above log(Mstar)˜10.5 MSun and have ongoing star formation (˜100 MSun/yr). The value of 10.5 MSun is similar to the characteristic mass for obscured AGN (Kauffmann et al. 2003) and radio-loud AGN (Best et al. 2005) in the SDSS. It is also consistent with the more general result that the fraction of galaxies hosting AGN increases with the stellar mass.

  20. A Search for Mass Loss on the Cepheid Instability Strip using H i 21 cm Line Observations

    NASA Astrophysics Data System (ADS)

    Matthews, L. D.; Marengo, M.; Evans, N. R.

    2016-12-01

    We present the results of a search for H i 21 cm line emission from the circumstellar environments of four Galactic Cepheids (RS Pup, X Cyg, ζ Gem, and T Mon) based on observations with the Karl G. Jansky Very Large Array. The observations were aimed at detecting gas associated with previous or ongoing mass loss. Near the long-period Cepheid T Mon, we report the detection of a partial shell-like structure whose properties appear consistent with originating from an earlier epoch of Cepheid mass loss. At the distance of T Mon, the nebula would have a mass (H i+He) of ˜ 0.5{M}⊙ , or ˜6% of the stellar mass. Assuming that one-third of the nebular mass comprises swept-up interstellar gas, we estimate an implied mass-loss rate of \\dot{M}˜ (0.6{--}2)× {10}-5 {M}⊙ yr-1. No clear signatures of circumstellar emission were found toward ζ Gem, RS Pup, or X Cyg, although in each case, line-of-sight confusion compromised portions of the spectral band. For the undetected stars, we derive model-dependent 3σ upper limits on the mass-loss rates, averaged over their lifetimes on the instability strip, of ≲ (0.3{--}6)× {10}-6 {M}⊙ yr-1 and estimate the total amount of mass lost to be less than a few percent of the stellar mass.

  1. Exploring the multifaceted circumstellar environment of the luminous blue variable HR Carinae

    NASA Astrophysics Data System (ADS)

    Buemi, C. S.; Trigilio, C.; Leto, P.; Umana, G.; Ingallinera, A.; Cavallaro, F.; Cerrigone, L.; Agliozzo, C.; Bufano, F.; Riggi, S.; Molinari, S.; Schillirò, F.

    2017-03-01

    We present a multiwavelength study of the Galactic luminous blue variable HR Carinae, based on new high-resolution mid-infrared (IR) and radio images obtained with the Very Large Telescope (VLT) and the Australia Telescope Compact Array (ATCA), which have been complemented by far-infrared Herschel-Photodetector Array Camera and Spectrometer (PACS) observations and ATCA archive data. The Herschel images reveal the large-scale distribution of the dusty emitting nebula, which extends mainly to the north-east direction, up to 70 arcsec from the central star, and is oriented along the direction of the space motion of the star. In the mid-infrared images, the brightness distribution is characterized by two arc-shaped structures, tracing an inner envelope surrounding the central star more closely. At radio wavelengths, the ionized gas emission lies on the opposite side of the cold dust with respect to the position of the star, as if the ionized front were confined by the surrounding medium in the north-south direction. Comparison with previous data indicates significant changes in the radio nebula morphology and in the mass-loss rate from the central star, which has increased from 6.1 × 10-6 M⊙ yr-1 in 1994-1995 to 1.17 × 10-5 M⊙ yr-1 in 2014. We investigate possible scenarios that could have generated the complex circumstellar environment revealed by our multiwavelength data.

  2. Primary productivity and the prospects for biofuels in the United Kingdom

    NASA Astrophysics Data System (ADS)

    Lawson, G. J.; Callaghan, T. V.

    1983-09-01

    Estimates of land use and plant productivity are combined to predict total annual primary production in the UK as 252 million tonnes dry matter (10.5 t ha-1yr-1). Annual above ground production is predicted to be 165 Mt (6.9 t ha-1yr-1). Within these totals, intensive agriculture contributes 60%, productive woodland 8%, natural vegetation 26% and urban vegetation 5%. However, only 25% of total plant production is cropped by man and animals, and most of this is subsequently discarded as wastes and residues. 2112 PJ of organic material is available for fuel without reducing food or fibre production, but since much of this could not be economically collected, 859 PJ is calculated as a more realistic biofuel contribution by the year 2000. After deducting 50% conversion losses, this could save P1 billion (1979 prices) in oil imports. Short rotation energy plantations, forest residues, coppice woodlands, animal and crop wastes, industrial and domestic wastes, catch crops, natural vegetation and urban vegetation all have immediate or short term potential as biofuel sources. Sensitive planning is required to reduce environmental impact, but in some cases more diverse wildlife habitats may be created.

  3. 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.

  4. 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

    2016-04-05

    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.

  5. 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.

  6. The rate, luminosity function and time delay of non-Collapsar short GRBs

    NASA Astrophysics Data System (ADS)

    Wanderman, David; Piran, Tsvi

    2015-04-01

    We estimate the rate and the luminosity function of short (hard) Gamma-Ray Bursts (sGRBs) that are non-Collapsars, using the peak fluxes and redshifts of BATSE, Swift and Fermi GRBs. Following Bromberg et al., we select a sub-sample of Swift bursts which are most likely non-Collapsars. We find that these sGRBs are delayed relative to the global star formation rate (SFR) with a typical delay time of a 3-4 Gyr (depending on the SFR model). However, if two or three sGRB at high redshifts have been missed because of selection effects, a distribution of delay times of ∝ 1/t would be also compatible. The current event rate of these non-Collapsar sGRBs with Liso > 5 × 1049 erg s-1 is 4.1_{-1.9}^{+2.3} Gpc^{-3} yr^{-1}. The rate was significantly larger around z ˜ 1 and it declines since that time. The luminosity function we find is a broken power law with a break at 2.0_{-0.4}^{+1.4} × 10^{52} erg s^{-1} and power-law indices 0.95_{-0.1 2}^{+0.12} and 2.0_{-0.8}^{+1.0}. When considering the whole Swift sGRB sample we find that it is composed of two populations: one group (≈60-80 per cent of Swift sGRBs) with the above rate and time delay and a second group (≈20-40 per cent of Swift sGRBs) of potential `impostors' that follow the SFR with no delay. These two populations are in very good agreement with the division of sGRBs to non-Collapsars and Collapsars suggested recently by Bromberg et al. If non-Collapsar sGRBs arise from neutron star merger this rate suggest a detection rate of 3-100 yr-1 by a future gravitational wave detectors (e.g. Advanced Ligo/Virgo with detection horizon on 300 Mpc), and a co-detection with Fermi (Swift ) rate of 0.1-1 yr-1 (0.02-0.14 yr-1). We estimate that about 4 × 10^5 (f_b^{-1}/30) mergers took place in the Milky Way. If 0.025M⊙ were ejected in each event this would have been sufficient to produce all the heavy r-process material in the Galaxy.

  7. Cluster Birth: New SCUBA and CS Results in S68N

    NASA Astrophysics Data System (ADS)

    Wolf-Chase, G. A.; Barsony, M. A.; Wootten, H. A.; Ward-Thompson, D.; Lowrance, P. J.; Kastner, J. H.; McMullin, J. P.

    1997-12-01

    We have discovered and mapped a compact (~ 80('') in extent) outflow from the gas-rich protostar, S68N, with newly combined single-dish (Haystack) and interferometer (BIMA) data. The outflow momentum flux is ~ 4.8 x 10(-4) Msun km s(-1) yr(-1) , or about two orders of magnitude larger than the average momentum flux for Class I objects, and one order of magnitude larger than the average momentum flux for Class 0 objects (e.g., Bontemps et al. 1996). Such a high momentum flux is a newly-found indicator of the extreme youth of Class 0 protostars. Our new CS J=2->1 results, combined with previous H_2CO data, suggest the simultaneous occurrence of infall and outflow in S68N (Hurt, Barsony, & Wootten 1996; McMullin et al. 1994). We have also mapped the S68N region at 450 mu m & 850 mu m, with SCUBA on the JCMT with 7('') and 14('') resolutions, respectively. In addition to S68N, the SCUBA maps also detect swept-up dust associated with the redshifted outflow lobe, as well as the Class I source, SMM5, 45('') to the East. We have discovered a new protostellar source 13('') to the NE of S68N, but only marginally detected a previously known 1.1 mm continuum peak, associated with submillimeter H_2CO emission, 27('') NW of S68N (Casali, Eiroa, & Duncan 1993; Barsony, Wootten, & Hurt, unpublished data). This 1(') region surrounding S68N in the Serpens cloud core (d=310 pc) contains a pre-protostellar core, a possible proto-binary, and a Class I protostar. We plan future line radiative transfer modelling, combined with higher resolution interferometric imaging of this source, to advance our understanding of cloud fragmentation processes leading to multiple system formation.

  8. Light elements as probes of weak stellar winds

    NASA Astrophysics Data System (ADS)

    Landstreet, J. D.; Dolez, N.; Vauclair, S.

    1998-05-01

    The possibility that stars of the upper main sequence possess weak winds (of order 10(-14) to 10(-12) Msun yr(-1) ) that may compete with atomic diffusion has been suggested by several authors, particularly by Babel & Michaud (1991a) and Babel (1992). Such winds may affect the chemical abundances that appear in the atmospheres of these stars. However, obtaining unambiguous evidence for the existence of a weak wind is not easy. We consider the possibility that naturally abundant chemical elements such as C, O and Ne, which are not expected to be made overabundant in a stellar atmosphere by radiative levitation, may accumulate in or near the photosphere of a mass-losing star, thus serving as tracers of mass loss. We first show that the most abundant elements are not expected to be overabundant in the atmospheres of main sequence stars in the range 8000 <= T_e <= 15000K due to radiative acceleration. We next show that hydrogen mass loss from the atmosphere, at a rate in the range of roughly 10(-14) <= dot {M} <= 10(-12) \\ M_{sunyr(-1}) , could lead to accumulation of a few abundant elements in or not far below the stellar photosphere, provided that any turbulence in the wind at the level of the photosphere is not sufficient to prevent diffusion. We find that such mass loss in late B stars should lead to observable overabundance of Ne, while in early A stars, such mass loss causes O to accumulate in the atmosphere. Detection of overabundances of these elements would provide direct evidence of the presence of weak mass loss. The few available Ne abundance determinations do not allow us to decide whether such weak winds are present in any B stars, but numerous measurements of O abundance imply that either winds in this mass loss range do not occur, or else that atmospheric diffusion is prevented by turbulence in early A stars.

  9. 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.; ...

    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

  10. 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.

  11. 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).

  12. 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.

  13. Nitrogen transfers and air-sea N2O fluxes in the upwelling off Namibia within the oxygen minimum zone: a 3-D model approach

    NASA Astrophysics Data System (ADS)

    Gutknecht, E.; Dadou, I.; Le Vu, B.; Cambon, G.; Sudre, J.; Garçon, V.; Machu, E.; Rixen, T.; Kock, A.; Flohr, A.; Paulmier, A.; Lavik, G.

    2011-04-01

    As regions of high primary production and being often associated to Oxygen Minimum Zones (OMZs), Eastern Boundary Upwelling Systems (EBUS) represent key regions for the oceanic nitrogen (N) cycle. Indeed, by exporting the Organic Matter (OM) and nutrients produced in the coastal region to the open ocean, EBUS can play an important role in sustaining primary production in subtropical gyres. Losses of fixed inorganic N, through denitrification and anammox processes and through nitrous oxide (N2O) emissions to the atmosphere, take place in oxygen depleted environments such as EBUS, and alleviate the role of these regions as a source of N. In the present study, we developed a 3-D coupled physical/biogeochemical (ROMS/BioBUS) model for investigating the full N budget in the Namibian sub-system of the Benguela Upwelling System (BUS). The different state variables of a climatological experiment have been compared to different data sets (satellite and in situ observations) and show that the model is able to represent this biogeochemical oceanic region. The N transfer is investigated in the Namibian upwelling system using this coupled model, especially in the Walvis Bay area between 22° S and 24° S where the OMZ is well developed (O2 < 0.5 ml O2 l-1). The upwelling process advects 24.2 × 1010 mol N yr-1 of nitrate enriched waters over the first 100 m over the slope and over the continental shelf. The meridional advection by the alongshore Benguela current brings also nutrient-rich waters with 21.1 × 1010 mol N yr-1. 10.5 × 1010 mol N yr-1 of OM are exported outside of the continental shelf (between 0 and 100-m depth). 32.4% and 18.1% of this OM are exported by advection in the form of Dissolved and Particulate Organic Matters (DOM and POM), respectively, however vertical sinking of POM represents the main contributor (49.5%) to OM export outside of the first 100-m depth of the water column on the continental shelf. The continental slope also represents a net N export

  14. New HI Clouds In The M81/M82 Group

    NASA Astrophysics Data System (ADS)

    Chynoweth, Katie M.; Langston, G.

    2007-12-01

    We present 5 newly discovered neutral hydrogen clouds in the M81/M82 group of galaxies, detected using the Robert C. Byrd Green Bank Telescope (GBT). All of the objects have properties similar to those of clouds previously found in our galaxy and other nearby galaxies. Based on the small angular distance of the clouds to group members, and the small velocity difference between group members and clouds, we conclude that the clouds are most likely stabilized relics of ongoing interactions between galaxies in the group. Our results are inconsistent with models of primordial HI clouds falling into the cluster. Previous studies of HI clouds have focused on the Milky Way and M31. Both galaxies are in a fairly relaxed state, and not currently interacting strongly with other galaxies. The M81/M82 group, in contrast, is highly unrelaxed and obviously interacting. Therefore, the study of HI clouds and other structures in the group is important in order to understand the full lifetime of these structures in relation to galaxy interactions. At 3.63 Mpc, the M81/M82 group is one of the closest groups, and because of its high declination and galactic latitude is an ideal location to search for analogs to local HVCs. We have searched the group in a 2° x 2° area, with a velocity range of greater than ± 500 km/s from any group galaxy, with a velocity resolution of 5.2 km/s. With a 7-sigma detection threshold of 8.4 x 10^5 M_Sun, we detect 5 HI clouds associated with the group, as well as associated filamentary HI structures. The clouds have masses between 10^6 and 10^7 M_Sun. The clouds are found only within small velocity differences from group members, and only at small angular separations. This work was supported by the NRAO Graduate Summer Student Research Assistantship Program.

  15. Ambient concentration and dry deposition of major inorganic nitrogen species at two urban sites in Sichuan Basin, China.

    PubMed

    Wang, Huanbo; Yang, Fumo; Shi, Guangming; Tian, Mi; Zhang, Leiming; Zhang, Liuyi; Fu, Chuan

    2016-12-01

    To assess pollution levels of major inorganic nitrogen species and their atmospheric deposition input to sensitive ecosystems in Sichuan Basin, southwest China, ambient concentrations of oxidized (NOy ∼ NO2, HNO3, NO3(-)) and reduced (NHx = NH3, NH4(+)) nitrogen species were collected at two urban sites during four one-month periods, each in a different season from July 2014 to April 2015. Estimated annual mean concentration of NOy was 20.3 and 13.5 μg N m(-3) in Chengdu and Wanzhou, respectively, and NHx was 16.9 and 13.6 μg N m(-3), respectively. Back trajectory cluster analysis indicated that high levels of NOy and NHx in Chengdu were mainly caused by local emissions while those in Wanzhou were caused by both the local emissions and long-range transport of pollutants. On annual basis, NO2 contributed the most to NOy, followed by NO3(-) and HNO3, accounting for 87.5%, 10.5% and 2.0%, respectively, of NOy in Chengdu, and 91.4%, 6.9% and 1.7%, respectively, in Wanzhou. NH3 was the predominant contributor to NHx, contributing 65.6% and 72.2% in Chengdu and Wanzhou, respectively. Dry deposition fluxes were estimated using the inferential method with measured ambient concentrations and modelled dry deposition velocities. The total inorganic nitrogen dry deposition flux was estimated to be 21.4 and 8.5 kg N ha(-1) yr(-1), with 44.3% and 41.4% from NOy in Chengdu and Wanzhou, respectively. NO2 and NH3 each contributed about 80% of NOy and NHx dry deposition, respectively. Wet deposition was only collected in Wanzhou, where the annual wet deposition of NO3(-) and NH4(+) was 4.5 and 15.7 kg N ha(-1) yr(-1), respectively. The total wet plus dry deposition was 28.7 kg N ha(-1) yr(-1) in Wanzhou with 72.2% from reduced nitrogen. Therefore, controlling NH3 emissions from agricultural, traffic, waste containers and sewage system sources would be effective to reduce the total nitrogen deposition in the Sichuan Basin area.

  16. Measurement of the Rate of Stellar Tidal Disruption Flares

    NASA Astrophysics Data System (ADS)

    van Velzen, Sjoert; Farrar, Glennys R.

    2014-09-01

    We report an observational estimate of the rate of stellar tidal disruption flares (TDFs) in inactive galaxies based on a successful search for these events among transients in galaxies using archival Sloan Digital Sky Survey (SDSS) multi-epoch imaging data (Stripe 82). This search yielded 186 nuclear flares in galaxies, 2 of which are excellent TDF candidates. Because of the systematic nature of the search, the very large number of galaxies, the long time of observation, and the fact that non-TDFs were excluded without resorting to assumptions about TDF characteristics, this study provides an unparalleled opportunity to measure the TDF rate. To compute the rate of optical stellar tidal disruption events, we simulate our entire pipeline to obtain the efficiency of detection. The rate depends on the light curves of TDFs, which are presently still poorly constrained. Using only the observed part of the SDSS light curves gives a model-independent upper limit to the optical TDF rate, \\dot{N}<2\\times 10^{-4}\\,yr^{-1}\\,galaxy^{-1} (90% CL), under the assumption that the SDSS TDFs are representative examples. We develop three empirical models of the light curves based on the two SDSS light curves and two more recent and better-sampled Pan-STARRS TDF light curves, leading to our best estimate of the rate: \\dot{N}_TDF = (1.5{--}2.0)_{-1.3}^{+2.7} \\times 10^{-5} \\,yr^{-1}\\, galaxy^{-1}. We explore the modeling uncertainties by considering two theoretically motivated light curve models, as well as two different relationships between black hole mass and galaxy luminosity, and two different treatments of the cutoff in the visibility of TDFs at large M BH. From this we conclude that these sources of uncertainty are not significantly larger than the statistical ones. Our results are applicable for galaxies hosting black holes with mass in the range of a few 106-108 M ⊙, and translates to a volumetric TDF rate of (4-8) × 10-8 ± 0.4 yr-1 Mpc-3, with the statistical

  17. Multi-gas and multi-source comparisons of six land use emission datasets and AFOLU estimates in the Fifth Assessment Report, for the tropics for 2000-2005

    NASA Astrophysics Data System (ADS)

    Roman-Cuesta, Rosa Maria; Herold, Martin; Rufino, Mariana C.; Rosenstock, Todd S.; Houghton, Richard A.; Rossi, Simone; Butterbach-Bahl, Klaus; Ogle, Stephen; Poulter, Benjamin; Verchot, Louis; Martius, Christopher; de Bruin, Sytze

    2016-10-01

    The Agriculture, Forestry and Other Land Use (AFOLU) sector contributes with ca. 20-25 % of global anthropogenic emissions (2010), making it a key component of any climate change mitigation strategy. AFOLU estimates, however, remain highly uncertain, jeopardizing the mitigation effectiveness of this sector. Comparisons of global AFOLU emissions have shown divergences of up to 25 %, urging for improved understanding of the reasons behind these differences. Here we compare a variety of AFOLU emission datasets and estimates given in the Fifth Assessment Report for the tropics (2000-2005) to identify plausible explanations for the differences in (i) aggregated gross AFOLU emissions, and (ii) disaggregated emissions by sources and gases (CO2, CH4, N2O). We also aim to (iii) identify countries with low agreement among AFOLU datasets to navigate research efforts. The datasets are FAOSTAT (Food and Agriculture Organization of the United Nations, Statistics Division), EDGAR (Emissions Database for Global Atmospheric Research), the newly developed AFOLU "Hotspots", "Houghton", "Baccini", and EPA (US Environmental Protection Agency) datasets. Aggregated gross emissions were similar for all databases for the AFOLU sector: 8.2 (5.5-12.2), 8.4, and 8.0 Pg CO2 eq. yr-1 (for Hotspots, FAOSTAT, and EDGAR respectively), forests reached 6.0 (3.8-10), 5.9, 5.9, and 5.4 Pg CO2 eq. yr-1 (Hotspots, FAOSTAT, EDGAR, and Houghton), and agricultural sectors were with 1.9 (1.5-2.5), 2.5, 2.1, and 2.0 Pg CO2 eq. yr-1 (Hotspots, FAOSTAT, EDGAR, and EPA). However, this agreement was lost when disaggregating the emissions by sources, continents, and gases, particularly for the forest sector, with fire leading the differences. Agricultural emissions were more homogeneous, especially from livestock, while those from croplands were the most diverse. CO2 showed the largest differences among the datasets. Cropland soils and enteric fermentation led to the smaller N2O and CH4 differences. Disagreements

  18. (7)Be in soil, deposited dust and atmospheric air and its using to infer soil erosion along Alexandria region, Egypt.

    PubMed

    Saleh, I H; Abdel-Halim, A A

    2017-03-14

    This study investigated the radioactivity behavior of (7)Be in surface soil, airborne and deposited dust along Alexandria region in Egypt. The results obtained were used to predict scavenging processes of (7)Be from surface soil to infer soil erosion and land vulnerable to accelerated sea-level rise. The areal activity concentrations of (7)Be in surface soil were investigated in 30 undisturbed sites and (7)Be inventories were determined via deposited dust in 10 locations. Results of the former were found to be ranged from 78 Bq/m(2) to 104 Bq/m(2). High levels were observed in western sites associated with high dust deposition rate. On the other hand, low levels were found in the eastern sites, those may be attributed to scavenging processes such as land erosion toward the direction to the sea. The effective removal rates of (7)Be were calculated using the box-model, showing a broad special trend of inventories generally decreasing eastwards. The scavenging rates were ranged between 3.13 yr(-1) in western sites to 5.34 yr(-1) in eastern ones which denote that the east of the city suffers from rapid soil erosion. The airborne (7)Be was monthly monitored along the period from October 2014 to September 2015 through one site located at the mid of the city. The results revealed lower values in winter and autumn than in summer and spring ranged between 6.2 mBq/m(3) and 10.5 mBq/m(3). These levels are comparable with that in other world regions and the seasonal variations are associated with the prevailing climatic conditions in Alexandria region.

  19. Modelling the circumstellar medium in RS Ophiuchi and its link to Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Booth, R. A.; Mohamed, S.; Podsiadlowski, Ph.

    2016-03-01

    Recent interpretations of narrow, variable absorption lines detected in some Type Ia supernovae suggest that their progenitors are surrounded by dense, circumstellar material. Similar variations detected in the symbiotic recurrent nova system RS Oph, which undergoes thermonuclear outbursts every 20 years, making it an ideal candidate to investigate the origin of these lines. To this end, we present simulations of multiple mass transfer-nova cycles in RS Oph. We find that the quiescent mass transfer produces a dense, equatorial outflow, i.e. concentrated towards the binary orbital plane, and an accretion disc forms around the white dwarf. The interaction of a spherical nova outburst with these aspherical circumstellar structures produces a bipolar outflow, similar to that seen in Hubble Space Telescope imaging of the 2006 outburst. In order to produce an ionization structure that is consistent with observations, a mass-loss rate of 5 × 10-7 M⊙ yr-1 from the red giant is required. The simulations also produce a polar accretion flow, which may explain the broad wings of the quiescent H line and hard X-rays. By comparing simulated absorption line profiles to observations of the 2006 outburst, we are able to determine which components arise in the wind and which are due to the novae. We explore the possible behaviour of absorption line profiles as they may appear should a supernova occur in a system like RS Oph. Our models show similarities to supernovae like SN 2006X, but require a high mass-loss rate, dot{M} ˜ 10^{-6}-10-5 M⊙ yr-1, to explain the variability in SN 2006X.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. On the use of the correction factor with Japanese ozonesonde data

    NASA Astrophysics Data System (ADS)

    Morris, G. A.; Labow, G.; Akimoto, H.; Takigawa, M.; Fujiwara, M.; Hasebe, F.; Hirokawa, J.; Koide, T.

    2013-02-01

    In submitting data to the World Meteorological Organization (WMO) World Ozone and Ultraviolet Data Center (WOUDC), numerous ozonesonde stations include a correction factor (CF) that multiplies ozone concentration profile data so that the columns computed agree with column measurements from co-located ground-based and/or overpassing satellite instruments. We evaluate this practice through an examination of data from four Japanese ozonesonde stations: Kagoshima, Naha, Sapporo, and Tsukuba. While agreement between the sonde columns and Total Ozone Mapping Spectrometer (TOMS) or Ozone Mapping Instrument (OMI) is improved by use of the CF, agreement between the sonde ozone concentrations reported near the surface and data from surface monitors near the launch sites is negatively impacted. In addition, we find the agreement between the mean sonde columns without the CF and the ground-based Dobson instrument columns is improved by ~1.5 % by using the McPeters et al. (1997) balloon burst climatology rather than the constant mixing ratio assumption (that has been used for the data in the WOUDC archive) for the above burst height column estimate. Limited comparisons of coincident ozonesonde profiles from Hokkaido University with those in the WOUDC database suggest that while the application of the CFs in the stratosphere improves agreement, it negatively impacts the agreement in the troposphere. Finally and importantly, unexplained trends and changing trends in the CFs appear over the last 20 years. The overall trend in the reported CFs for the four Japanese ozonesonde stations from 1990-2010 is (-0.264 ± 0.036) × 10-2 yr-1; but from 1993-1999 the trend is (-2.18 ± 0.14) × 10-2 yr-1 and from 1999-2009 is (1.089 ± 0.075) × 10-2 yr-1, resulting in a statistically significant difference in CF trends between these two periods of (3.26 ± 0.16) × 10-2 yr-1. Repeating the analysis using CFs derived from columns computed using the balloon-burst climatology, the trends are

  5. A Photometric and Spectroscopic Study of Massive and Evolved Galaxies at z > 3

    NASA Astrophysics Data System (ADS)

    Nayyeri, Hooshang

    I use deep data taken as part of the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) observations by the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) along with ground-based and Spitzer Space Telescope data to identify massive and evolved galaxies at z > 3. This is performed using the strength of the Balmer break feature at rest-frame 3648AA, which is an age dependent diagnostic of the stellar population, to develop a Balmer Break Galaxy (BBG) selection. Fitting the spectral energy distribution (SED) of the candidates show that these systems have average estimated ages of ~ 800 Myr and average stellar masses of ~ 5 x1010M_sun, consistent with being old and massive. I find a number density of ~ 3.2 x 10--5 Mpc--3 for these systems corresponding to a mass density of ~ 2.0 x 106 M_sun/Mpc3 at 3 < z < 3 are far more compact than lower redshift early type galaxies. Using the GALFIT measured sizes, I confirm that the physical size of the early type galaxies evolve rapidly with redshift according to: Re ∝ (1 + z) --1.48 out to z ~ 3.3.

  6. Imaging Cold Gas to 1 kpc scales in high-redshift galaxies with the ngVLA

    NASA Astrophysics Data System (ADS)

    Casey, Caitlin; Narayanan, Desika; Dave, Romeel; Hung, Chao-Ling; Champagne, Jaclyn; Carilli, Chris Luke; Decarli, Roberto; Murphy, Eric J.; Popping, Gergo; Riechers, Dominik; Somerville, Rachel S.; Walter, Fabian

    2017-01-01

    The next generation Very Large Array (ngVLA) will revolutionize our understanding of the distant Universe via the detection of cold molecular gas in the first galaxies. Its impact on studies of galaxy characterization via detailed gas dynamics will provide crucial insight on dominant physical drivers for star-formation in high redshift galaxies, including the exchange of gas from scales of the circumgalactic medium down to resolved clouds on mass scales of ~10^5 M_sun. In this study, we employ a series of high-resolution, cosmological, hydrodynamic zoom simulations from the MUFASA simulation suite and a CASA simulator to generate mock ngVLA observations. Based on a direct comparison between the inferred results from our mock observations and the cosmological simulations, we investigate the capabilities of ngVLA to constrain the mode of star formation, dynamical mass, and molecular gas kinematics in individual high-redshift galaxies using cold gas tracers like CO(1-0) and CO(2-1). Using the Despotic radiative transfer code that encompasses simultaneous thermal and statistical equilibrium in calculating the molecular and atomic level populations, we generate parallel mock observations of high-J transitions of CO and C+ from ALMA for comparison. The factor of 100 times improvement in mapping speed for the ngVLA beyond the Jansky VLA and the proposed ALMA Band 1 will make these detailed, high-resolution imaging and kinematic studies routine at z=2 and beyond.

  7. Discovery of calcite in the solar type protostar NGC 1333-IRAS 4

    NASA Astrophysics Data System (ADS)

    Ceccarelli, C.; Caux, E.; Tielens, A. G. G. M.; Kemper, F.; Waters, L. B. F. M.; Phillips, T.

    2002-11-01

    We present observations, obtained with ISO-LWS, of the continuum between 50-200 mu m of the solar type protostar IRAS 4, in the NGC 1333 complex. The continuum presents an excess, around 95 mu m, that we demonstrate must be a dust feature. We compared the 95 mu m excess with the calcite feature at 92 mu m and find that it fits the observations reasonably well. There may be a further contribution from hydrous silicates at ~ 100 mu m, but this seems a less robust result. The detected calcite mass is ~ 8 x 10-5 Msun and represents about 1% of the warm ( ~ 23 K) dust mass surrounding IRAS 4. This is only the second observation indicating the presence of carbonates outside the solar system, and the first revealing calcite in a young protostar. It is remarkable and intriguing that in all the objects where calcite has been detected so far, namely meteorites, planetary nebulae and IRAS 4, it represents from 0.3 to 1% of the dust mass. This new detection of calcite strengthens the claim by Kemper et al. (2002a) that calcite formation does not necessarely requires liquid water. We suggest that calcite forms at the surface of the grains, where water ice layers may locally have an enhanced mobility caused by heating due to hard X-rays emitted by the central object.

  8. Carbon sequestration in forest soils - Results from input-output balances

    NASA Astrophysics Data System (ADS)

    Brumme, Dr

    2009-04-01

    Input-output balances of 53 forest ecosystems were used to calculate the N-induced C-sequestration in forest soils. Input and output measurements were conducted in spruce, pine, beech and oak forests over an 8-years period. N-input ranged from 7-37 kg N ha-1 yr-1 and N-output from 0-27 kg ha-1 yr-1. N-retention in soils was estimated by subtracting N-leaching and N-increments in plants from total deposition assuming similar values for gaseous N-losses and N-fixation (Brumme & Khanna 2008). Soil N-changes ranged from -24 kg to 21 kg N ha-1 yr-1. Negative balances are explained by humus degradation in the mineral soil (n=9), positive values by N-accumulation in the forest floor (n=44). C-sequestration was calculated by corresponding C/N values in the forest floor and the top mineral soil (0-5 cm depth). C-losses from the mineral soil were lower than 290 kg ha-1 yr-1 and C-gain lower than 590 kg ha-1 yr-1. Since the C-losses from the mineral soil did not originate from N-deposition only positive values were used to calculate the N-induced C-sequestration in the forest floor. C-sequestration ranged from 1 kg to 590 ha-1 yr-1. The highest sink was observed for spruce forests (250 ha-1 yr-1, n=14), fallowed by pine (170 ha-1 yr-1, n=11), beech (137 ha-1 yr-1, n=13), and oak (94 ha-1 yr-1, n=6). The overall mean value for C-sequestration is 176 ha-1 yr-1 (sd 140 kg ha-1 yr-1). Brumme R, Khanna PK (2008) Ecological and site historical aspects of N dynamics and current N status in temperate forests. Global Change Biology 14, 125-141

  9. 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

  10. 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

  11. V1974 Cygni 1992: Optical and Ultraviolet Evolution and Analysis

    NASA Astrophysics Data System (ADS)

    Austin, S. J.; Wagner, R. M.; Starrfield, S.; Shore, S. N.; Sonneborn, G.; Bertram, R.

    1996-02-01

    We have obtained optical spectrophotometry of V1974 Cygni (Nova Cygni 1992), the brightest nova since 1975, from day 4 to 540 after visual maximum, which we have combined with ultraviolet spectrophotometry to study the ejecta. We show high quality ultraviolet and optical spectra at each major evolutionary phase, identify the lines present during the nebular phase, and show the temporal development of the emission line fluxes and widths. The optical spectral evolution of this nova, using the CTIO system, was PFe,N,ANe. V1974 Cygni is classified as a "neon nova" since [Ne III] λ3869 and [Ne V] λ3425 were the strongest emission lines during the nebular phase. We determined the physical conditions and elemental abundances of the ejecta during the optically thin phase. Because the densities were high and the shell was not spatially resolved we have developed a completely new method which involves the combination of photoionization models and a multiparameter Monte Carlo fitting of the relative emission-line fluxes. The line spectra from days 300, 400, and 500 were modeled, and the inhomogeneity of the ejected material was simulated by considering large variations in the filling and covering factors, as well as letting the density vary as a function of radius. Enhancements above solar were found for He, N, 0, Ne, and Fe with abundances by (number relative to solar and with 90% confidence uncertainties) of N(He)/N =4.4+9-3, N(N)/NH=282+117-192, N(O)/NH=110+43-67, N(Ne)/NH=250+150-159, and N(Fe)/NH=16+28-12. The large neon abundance can only be explained by the ejection of core material from an ONeMg white dwarf. The resulting helium abundance places the ejected mass at about S X 10-5 Msun. This ejected mass and x-ray studies were used to estimate that the mass of the white dwarf is about 1.3 Msun. Line profiles of Balmer, nebular, and coronal lines, obtained in high resolution during the nebular phase, exhibit nearly identical multicomponent, symmetric sawtooth shapes

  12. Masses of the components of the HDE226868/Cyg X-1 binary system

    NASA Astrophysics Data System (ADS)

    Ziolkowski, Janusz

    Recent determination of the distance to HDE 226868/Cyg X-1 binary system (Reid et al., 2011) and more precise determination of the effective temperature of HDE 226868 (Caballero-Nieves et al., 2009) permit a more accurate estimate of the masses of both components. Using up to date evolutionary models, I obtain a mass range of between 25 to 35 Msun for the mass of the supergiant and between 13 to 23 Msun for the mass of the black hole. Accepting more liberal estimates of uncertainties in both the distance and the effective temperature, one may extend these ranges to 21 to 35 Msun and 10 to 23 Msun for both masses, respectively. The most likely values within these ranges are, respectively, 27Msun and 16Msun. The obtained mass of black hole agrees with the value 15 ± 1 Msun suggested by Orosz et al. (2011). However, the value suggested by them for the mass of the supergiant of 19 ± 2 Msun should not be used as such a star violates the mass-luminosity relation for the the massive core hydrogen burning stars. This consideration was not incorporated into the iterative process of Orosz et al. To resolve this violation I consider the possibility that the hydrogen content of HDE 222268 might be lowered as a result of the mass transfer and the induced fast rotation of the mass gainer. I analyzed the evolutionary effects of such situation and found that, while important, they do not invalidate the conclusions listed above. If, as a result of the rotation induced mixing, the present hydrogen content of HDE 226868 is equal about 0.6 (as suggested by some observational data), then its present mass may be somewhat lower: about 24 Msun rather than about 27 Msun.

  13. The Envelopes of B[e] Supergiants in the Magellanic Clouds as Seen by Polarimetry

    NASA Astrophysics Data System (ADS)

    Seriacopi, D. B.; Carciofi, A. C.; Magalhães, A. M.

    2017-02-01

    B[e] supergiants (sgB[e]) are rare, massive post-main sequence stars. Their evolutionary status with respect to other objects on the H-R diagram is still unknown. These stars are surrounded by a non-spherically symmetric circumstellar envelope, from which arises a net intrinsic polarization. Therefore, spectropolarimetry is a very useful tool in the study of these objects. Since emission, absorption, and scattering processes are imprinted in the polarized flux, this technique can provide useful information about the circumstellar structure. We present a study of the envelope structure of RMC 82, a sgB[e] in the Large Magellanic Cloud, based on spectropolarimetric data. Our observations were obtained with the 8.2 m VLT/UT1 telescope at the Paranal Observatory (ESO). We analyzed the Balmer line formation loci, and their corresponding physical conditions. The data was modeled by a bimodal wind model of the circumstellar envelope, consisting of a slow, dense equatorial wind and a fast polar wind. The calculations were done with the radiative transfer code HDUST. Our results suggest that this geometry is indeed consistent with the RMC 82 data. Our best fit parameters are an opening angle of the disk of 15° and a total mass loss rate of 1.0×10-5 M⊙ yr-1 sr-1.

  14. Discovery, Progenitor and Early Evolution of a Stripped Envelope Supernova iPTF13bvn

    NASA Astrophysics Data System (ADS)

    Cao, Yi; Kasliwal, Mansi M.; Arcavi, Iair; Horesh, Assaf; Hancock, Paul; Valenti, Stefano; Cenko, S. Bradley; Kulkarni, S. R.; Gal-Yam, Avishay; Gorbikov, Evgeny; Ofek, Eran O.; Sand, David; Yaron, Ofer; Graham, Melissa; Silverman, Jeffrey M.; Wheeler, J. Craig; Marion, G. H.; Walker, Emma S.; Mazzali, Paolo; Howell, D. Andrew; Li, K. L.; Kong, A. K. H.; Bloom, Joshua S.; Nugent, Peter E.; Surace, Jason; Masci, Frank; Carpenter, John; Degenaar, Nathalie; Gelino, Christopher R.

    2013-09-01

    The intermediate Palomar Transient Factory reports our discovery of a young supernova, iPTF13bvn, in the nearby galaxy, NGC 5806 (22.5 Mpc). Our spectral sequence in the optical and infrared suggests a Type Ib classification. We identify a blue progenitor candidate in deep pre-explosion imaging within a 2σ error circle of 80 mas (8.7 pc). The candidate has an MB luminosity of -5.52 ± 0.39 mag and a B - I color of 0.25 ± 0.25 mag. If confirmed by future observations, this would be the first direct detection for a progenitor of a Type Ib. Fitting a power law to the early light curve, we find an extrapolated explosion date around 0.6 days before our first detection. We see no evidence of shock cooling. The pre-explosion detection limits constrain the radius of the progenitor to be smaller than a few solar radii. iPTF13bvn is also detected in centimeter and millimeter wavelengths. Fitting a synchrotron self-absorption model to our radio data, we find a mass-loading parameter of 1.3×1012 g cm-1. Assuming a wind velocity of 103 km s-1, we derive a progenitor mass-loss rate of 3 × 10-5 M ⊙ yr-1. Our observations, taken as a whole, are consistent with a Wolf-Rayet progenitor of the supernova iPTF13bvn.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Ultra-High-Energy Cosmic-Ray Acceleration by Magnetic Reconnection in Newborn Accretion-induced Collapse Pulsars.

    PubMed

    de Gouveia Dal Pino EM; Lazarian

    2000-06-10

    We here investigate the possibility that the ultra-high-energy cosmic-ray (UHECR) events observed above the Greisen-Zatsepin-Kuzmin (GZK) limit are mostly protons accelerated in reconnection sites just above the magnetosphere of newborn millisecond pulsars that are originated by accretion-induced collapse (AIC). We formulate the requirements for the acceleration mechanism and show that AIC pulsars with surface magnetic fields 1012 G/=10(20) eV. Because the expected rate of AIC sources in our Galaxy is very small ( approximately 10(-5) yr(-1)), the corresponding contribution to the flux of UHECRs is negligible and the total flux is given by the integrated contribution from AIC sources produced by the distribution of galaxies located within the distance that is unaffected by the GZK cutoff ( approximately 50 Mpc). We find that reconnection should convert a fraction xi greater, similar0.1 of magnetic energy into UHECRs in order to reproduce the observed flux.

  5. ALMA observations of the supergiant B[e] star Wd1-9

    NASA Astrophysics Data System (ADS)

    Fenech, D. M.; Clark, J. S.; Prinja, R. K.; Morford, J. C.; Dougherty, S.; Blomme, R.

    2017-01-01

    Mass-loss in massive stars plays a critical role in their evolution, although the precise mechanism(s) responsible - radiatively driven winds, impulsive ejection and/or binary interaction - remain uncertain. In this Letter, we present Atacama Large Millimetre/Submillimeter Array line and continuum observations of the supergiant B[e] star Wd1-9, a massive post-main-sequence object located within the starburst cluster Westerlund 1 (Wd1). We find it to be one of the brightest stellar point sources in the sky at millimetre wavelengths, with (serendipitously identified) emission in the H41α radio recombination line. We attribute these properties to a low velocity (˜100 km s-1 ) ionized wind, with an extreme mass-loss rate ≳6.4 × 10-5(d/5 kpc)1.5 M⊙yr- 1. External to this is an extended aspherical ejection nebula indicative of a prior phase of significant mass-loss. Taken together, the millimetre properties of Wd1-9 show a remarkable similarity to those of the highly luminous stellar source MWC349A. We conclude that these objects are interacting binaries evolving away from the main sequence and undergoing rapid case-A mass transfer. As such they - and by extension the wider class of supergiant B[e] stars - may provide a unique window into the physics of a process that shapes the life-cycle of ˜70 per cent of massive stars found in binary systems.

  6. An Ultra-fast X-Ray Disk Wind in the Neutron Star Binary GX 340+0

    NASA Astrophysics Data System (ADS)

    Miller, J. M.; Raymond, J.; Cackett, E.; Grinberg, V.; Nowak, M.

    2016-05-01

    We present a spectral analysis of a brief Chandra/HETG observation of the neutron star low-mass X-ray binary GX 340+0. The high-resolution spectrum reveals evidence of ionized absorption in the Fe K band. The strongest feature, an absorption line at approximately 6.9 keV, is required at the 5σ level of confidence via an F-test. Photoionization modeling with XSTAR grids suggests that the line is the most prominent part of a disk wind with an apparent outflow speed of v = 0.04c. This interpretation is preferred at the 4σ level over a scenario in which the line is H-like Fe xxvi at a modest redshift. The wind may achieve this speed owing to its relatively low ionization, enabling driving by radiation pressure on lines; in this sense, the wind in GX 340+0 may be the stellar-mass equivalent of the flows in broad absorption line quasars. If the gas has a unity volume filling factor, the mass ouflow rate in the wind is over 10-5 M ⊙ yr-1, and the kinetic power is nearly 1039 erg s-1 (or, 5-6 times the radiative Eddington limit for a neutron star). However, geometrical considerations—including a small volume filling factor and low covering factor—likely greatly reduce these values.

  7. T Pyxidis: death by a thousand novae

    NASA Astrophysics Data System (ADS)

    Patterson, Joseph; Oksanen, Arto; Kemp, Jonathan; Monard, Berto; Rea, Robert; Hambsch, Franz-Josef; McCormick, Jennie; Nelson, Peter; Allen, William; Krajci, Thomas; Lowther, Simon; Dvorak, Shawn; Borgman, Jordan; Richards, Thomas; Myers, Gordon; Harlingten, Caisey; Bolt, Greg

    2017-04-01

    We report a 20-yr campaign to track the 1.8 h photometric (and orbital) wave in the recurrent nova T Pyxidis. Before and after the 2011 eruption, the period increased on a time-scale P/dot{P} = 3 × 105 yr. This suggests a mass transfer rate in quiescence of ∼10-7 M⊙ yr-1, in substantial agreement with the accretion rate based on the star's luminosity. During the eruption itself, a rapid period increase of 0.0054(7) per cent occurred. This is probably a measure of the mass ejected in the outburst. For a plausible choice of binary parameters, that mass is at least 3 × 10-5 M⊙, and probably more. This represents >300 yr of accretion at the pre-outburst rate, but the time between outbursts was only 45 yr. Thus, the erupting white dwarf (WD) seems to have ejected at least six times more mass than it accreted. If this eruption is typical, the WD must be eroding, rather than growing, in mass. Unless the present series of eruptions is a short-lived episode, the binary dynamics will evaporate the secondary in ∼105 yr. This could be a major channel by which short-period cataclysmic variables are removed from the population.

  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.

    2012-06-01

    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.

  9. 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).

  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. 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.

  12. 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.

  13. 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.

  14. A Substantial Population of Massive Quiescent Galaxies at z ~ 4 from ZFOURGE

    NASA Astrophysics Data System (ADS)

    Straatman, Caroline M. S.; Labbé, Ivo; Spitler, Lee R.; Allen, Rebecca; Altieri, Bruno; Brammer, Gabriel B.; Dickinson, Mark; van Dokkum, Pieter; Inami, Hanae; Glazebrook, Karl; Kacprzak, Glenn G.; Kawinwanichakij, Lalit; Kelson, Daniel D.; McCarthy, Patrick J.; Mehrtens, Nicola; Monson, Andy; Murphy, David; Papovich, Casey; Persson, S. Eric; Quadri, Ryan; Rees, Glen; Tomczak, Adam; Tran, Kim-Vy H.; Tilvi, Vithal

    2014-03-01

    We report the likely identification of a substantial population of massive M ~ 1011 M ⊙ galaxies at z ~ 4 with suppressed star formation rates (SFRs), selected on rest-frame optical to near-IR colors from the FourStar Galaxy Evolution Survey (ZFOURGE). The observed spectral energy distributions show pronounced breaks, sampled by a set of near-IR medium-bandwidth filters, resulting in tightly constrained photometric redshifts. Fitting stellar population models suggests large Balmer/4000 Å breaks, relatively old stellar populations, large stellar masses, and low SFRs, with a median specific SFR of 2.9 ± 1.8 × 10-11 yr-1. Ultradeep Herschel/PACS 100 μm, 160 μm and Spitzer/MIPS 24 μm data reveal no dust-obscured SFR activity for 15/19(79%) galaxies. Two far-IR detected galaxies are obscured QSOs. Stacking the far-IR undetected galaxies yields no detection, consistent with the spectral energy distribution fit, indicating independently that the average specific SFR is at least 10 × smaller than that of typical star-forming galaxies at z ~ 4. Assuming all far-IR undetected galaxies are indeed quiescent, the volume density is 1.8 ± 0.7 × 10-5 Mpc-3 to a limit of log10 M/M ⊙ >= 10.6, which is 10 × and 80 × lower than at z = 2 and z = 0.1. They comprise a remarkably high fraction (~35%) of z ~ 4 massive galaxies, suggesting that suppression of star formation was efficient even at very high redshift. Given the average stellar age of 0.8 Gyr and stellar mass of 0.8 × 1011 M ⊙, the galaxies likely started forming stars before z = 5, with SFRs well in excess of 100 M ⊙ yr-1, far exceeding that of similarly abundant UV-bright galaxies at z >= 4. This suggests that most of the star formation in the progenitors of quiescent z ~ 4 galaxies was obscured by dust. This Letter contains data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

  15. Abiotic methane flux from the Chimaera seep and Tekirova ophiolites (Turkey): Understanding gas exhalation from low temperature serpentinization and implications for Mars

    NASA Astrophysics Data System (ADS)

    Etiope, Giuseppe; Schoell, Martin; Hosgörmez, Hakan

    2011-10-01

    The emission of abiotic methane (CH 4) into the atmosphere from low temperature serpentinization in ophiolitic rocks is documented to date only in four countries, the Philippines, Oman, New Zealand, and Turkey. Serpentinization produces large amounts of hydrogen (H 2) which in theory may react with CO 2 or CO to form hydrocarbons (Fischer-Tropsch Type synthesis, FTT). Similar mechanisms have been invoked to explain the CH 4 detected on Mars, so that understanding flux and exhalation modality of ophiolitic gas on Earth may contribute to decipher the potential degassing on Mars. This work reports the first direct measurements of gas (CH 4, CO 2) flux ever done on onshore ophiolites with present-day serpentinization. We investigated the Tekirova ophiolites at Çirali, in Turkey, hosting the Chimaera seep, a system of gas vents issuing from fractures in a 5000 m 2 wide ophiolite outcrop. At this site at least 150-190 t of CH 4 is annually released into the atmosphere. The molecular and isotopic compositions of C 1-C 5 alkanes, CO 2, and N 2 combined with source rock maturity data and thermogenic gas formation modelling suggested a dominant abiotic component (~ 80-90%) mixed with thermogenic gas. Abiotic H 2-rich gas is likely formed at temperatures below 50 °C, suggested by the low deuterium/hydrogen isotopic ratio of H 2 (δD H2: - 720‰), consistent with the low geothermal gradient of the area. Abiotic gas synthesis must be very fast and effective in continuously producing an amount of gas equivalent to the long-lasting (> 2 millennia) emission of > 100 t CH 4 yr - 1 , otherwise pressurised gas accumulation must exist. Over the same ophiolitic formation, 3 km away from Chimaera, we detected an invisible microseepage of abiotic CH 4 with fluxes from 0.07 to 1 g m - 2 d - 1 . On Mars similar fluxes could be able to sustain the CH 4 plume apparently recognised in the Northern Summer 2003 (10 4 or 10 5 t yr - 1 ) over the wide olivine bedrock and outcrops of hydrated

  16. 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.

  17. 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.

  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. 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.

  20. 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

  1. The carbon budget of South Asia

    NASA Astrophysics Data System (ADS)

    Patra, P. K.; Canadell, J. G.; Houghton, R. A.; Piao, S. L.; Oh, N.-H.; Ciais, P.; Manjunath, K. R.; Chhabra, A.; Wang, T.; Bhattacharya, T.; Bousquet, P.; Hartman, J.; Ito, A.; Mayorga, E.; Niwa, Y.; Raymond, P.; Sarma, V. V. S. S.; Lasco, R.

    2012-10-01

    The source and sinks of carbon dioxide (CO2) and methane (CH4) due to anthropogenic and natural biospheric activities were estimated for the South Asia region (Bangladesh, Bhutan, India, Nepal, Pakistan and Sri Lanka). Flux estimates were based on top-down methods that use inversions of atmospheric data, and bottom-up methods that use field observations, satellite data, and terrestrial ecosystem models. Based on atmospheric CO2 inversions, the net biospheric CO2 flux in South Asia (equivalent to the Net Biome Productivity, NBP) was a sink, estimated at -104 ± 150 Tg C yr-1 during 2007-2008. Based on the bottom-up approach, the net biospheric CO2 flux is estimated to be -191 ± 193 Tg C yr-1 during the period of 2000-2009. This last net flux results from the following flux components: (1) the Net Ecosystem Productivity, NEP (net primary production minus heterotrophic respiration) of -220 ± 186 Tg C yr-1 (2) the annual net carbon flux from land-use change of -14 ± 50 Tg C yr-1, which resulted from a sink of -16 Tg C yr-1 due to the establishment of tree plantations and wood harvest, and a source of 2 Tg C yr-1 due to the expansion of croplands; (3) the riverine export flux from terrestrial ecosystems to the coastal oceans of +42.9 Tg C yr-1; and (4) the net CO2 emission due to biomass burning of +44.1 ± 13.7 Tg C yr-1. Including the emissions from the combustion of fossil fuels of 444 Tg C yr-1 for the decades of 2000s, we estimate a net CO2 land-to-atmosphere flux of 297 Tg C yr-1. In addition to CO2, a fraction of the sequestered carbon in terrestrial ecosystems is released to the atmosphere as CH4. Based on bottom-up and top-down estimates, and chemistry-transport modeling, we estimate that 37 ± 3.7 Tg C-CH4 yr-1 were released to atmosphere from South Asia during the 2000s. Taking all CO2 and CH4 fluxes together, our best estimate of the net land-to-atmosphere CO2-equivalent flux is a net source of 334 Tg C yr-1 for the South Asia region during the 2000s. If

  2. The carbon budget of South Asia

    NASA Astrophysics Data System (ADS)

    Patra, P. K.; Canadell, J. G.; Houghton, R. A.; Piao, S. L.; Oh, N.-H.; Ciais, P.; Manjunath, K. R.; Chhabra, A.; Wang, T.; Bhattacharya, T.; Bousquet, P.; Hartman, J.; Ito, A.; Mayorga, E.; Niwa, Y.; Raymond, P. A.; Sarma, V. V. S. S.; Lasco, R.

    2013-01-01

    The source and sinks of carbon dioxide (CO2) and methane (CH4) due to anthropogenic and natural biospheric activities were estimated for the South Asian region (Bangladesh, Bhutan, India, Nepal, Pakistan and Sri Lanka). Flux estimates were based on top-down methods that use inversions of atmospheric data, and bottom-up methods that use field observations, satellite data, and terrestrial ecosystem models. Based on atmospheric CO2 inversions, the net biospheric CO2 flux in South Asia (equivalent to the Net Biome Productivity, NBP) was a sink, estimated at -104 ± 150 Tg C yr-1 during 2007-2008. Based on the bottom-up approach, the net biospheric CO2 flux is estimated to be -191 ± 193 Tg C yr-1 during the period of 2000-2009. This last net flux results from the following flux components: (1) the Net Ecosystem Productivity, NEP (net primary production minus heterotrophic respiration) of -220 ± 186 Tg C yr-1 (2) the annual net carbon flux from land-use change of -14 ± 50 Tg C yr-1, which resulted from a sink of -16 Tg C yr-1 due to the establishment of tree plantations and wood harvest, and a source of 2 Tg C yr-1 due to the expansion of croplands; (3) the riverine export flux from terrestrial ecosystems to the coastal oceans of +42.9 Tg C yr-1; and (4) the net CO2 emission due to biomass burning of +44.1 ± 13.7 Tg C yr-1. Including the emissions from the combustion of fossil fuels of 444 Tg C yr-1 for the 2000s, we estimate a net CO2 land-atmosphere flux of 297 Tg C yr-1. In addition to CO2, a fraction of the sequestered carbon in terrestrial ecosystems is released to the atmosphere as CH4. Based on bottom-up and top-down estimates, and chemistry-transport modeling, we estimate that 37 ± 3.7 Tg C yr-1 were released to atmosphere from South Asia during the 2000s. Taking all CO2 and CH4 fluxes together, our best estimate of the net land-atmosphere CO2-equivalent flux is a net source of 334 Tg C yr-1 for the South Asian region during the 2000s. If CH4 emissions are

  3. Branching ratios for the reaction of selected carbonyl-containing peroxy radicals with hydroperoxy radicals.

    PubMed

    Hasson, Alam S; Tyndall, Geoffrey S; Orlando, John J; Singh, Sukhdeep; Hernandez, Samuel Q; Campbell, Sean; Ibarra, Yesenia

    2012-06-21

    An important chemical sink for organic peroxy radicals (RO(2)) in the troposphere is reaction with hydroperoxy radicals (HO(2)). Although this reaction is typically assumed to form hydroperoxides as the major products (R1a), acetyl peroxy radicals and acetonyl peroxy radicals have been shown to undergo other reactions (R1b) and (R1c) with substantial branching ratios: RO(2) + HO(2) → ROOH + O(2) (R1a), RO(2) + HO(2) → ROH + O(3) (R1b), RO(2) + HO(2) → RO + OH + O(2) (R1c). Theoretical work suggests that reactions (R1b) and (R1c) may be a general feature of acyl peroxy and α-carbonyl peroxy radicals. In this work, branching ratios for R1a-R1c were derived for six carbonyl-containing peroxy radicals: C(2)H(5)C(O)O(2), C(3)H(7)C(O)O(2), CH(3)C(O)CH(2)O(2), CH(3)C(O)CH(O(2))CH(3), CH(2)ClCH(O(2))C(O)CH(3), and CH(2)ClC(CH(3))(O(2))CHO. Branching ratios for reactions of Cl-atoms with butanal, butanone, methacrolein, and methyl vinyl ketone were also measured as a part of this work. Product yields were determined using a combination of long path Fourier transform infrared spectroscopy, high performance liquid chromatography with fluorescence detection, gas chromatography with flame ionization detection, and gas chromatography-mass spectrometry. The following branching ratios were determined: C(2)H(5)C(O)O(2), Y(R1a) = 0.35 ± 0.1, Y(R1b) = 0.25 ± 0.1, and Y(R1c) = 0.4 ± 0.1; C(3)H(7)C(O)O(2), Y(R1a) = 0.24 ± 0.15, Y(R1b) = 0.29 ± 0.1, and Y(R1c) = 0.47 ± 0.15; CH(3)C(O)CH(2)O(2), Y(R1a) = 0.75 ± 0.13, Y(R1b) = 0, and Y(R1c) = 0.25 ± 0.13; CH(3)C(O)CH(O(2))CH(3), Y(R1a) = 0.42 ± 0.1, Y(R1b) = 0, and Y(R1c) = 0.58 ± 0.1; CH(2)ClC(CH(3))(O(2))CHO, Y(R1a) = 0.2 ± 0.2, Y(R1b) = 0, and Y(R1c) = 0.8 ± 0.2; and CH(2)ClCH(O(2))C(O)CH(3), Y(R1a) = 0.2 ± 0.1, Y(R1b) = 0, and Y(R1c) = 0.8 ± 0.2. The results give insights into possible mechanisms for cycling of OH radicals in the atmosphere.

  4. Strain accumulation near Yucca Mountain, Nevada, 1993-1998

    NASA Astrophysics Data System (ADS)

    Savage, J. C.; Svarc, J. L.; Prescott, W. H.

    2001-01-01

    A 50-km aperture geodetic network centered on the proposed high-level radioactive waste disposal site at Yucca Mountain, Nevada, was surveyed with GPS in 1993 and 1998. The average deformation rate across the area is described by the principal strain rates 22.8±8.8 nstrain yr-1 N77.6°W±13.5° and -8.8±11.9 nstrain yr-1 N12.5°E±13.5° (extension reckoned positive) and a clockwise rotation rate about a vertical axis of 9.6±7.4 nrad yr-1 relative to fixed North America. Quoted uncertainties are standard deviations. Those strain rates are consistent with the geodetic strain rates (2±12 nstrain yr-1 N87°±12°W and -22±12 nstrain yr-1 N03°±12°E) previously reported by Savage et al. [1999] for the 1983-1998 interval and with the low extension rate (5-20 nstrain yr-1) [Marrett et al., 1998] inferred from the geologic record. None of those strain rates is consistent with the 50±9 nstrain yr-1 N65°W extension rate for the area reported by Wernicke et al. [1998].

  5. Organic carbon burial rates in the Baltic Sea sediments

    NASA Astrophysics Data System (ADS)

    Winogradow, A.; Pempkowiak, J.

    2014-02-01

    Recent studies indicate the important role of the marine environment in the circulation of CO2. This is due to the occurrence of the so called "biological pump" mechanism. A special role in this process is played by the shelf seas. The paper presents estimates of organic carbon burial rates in the Baltic Sea sediments. Quantification of the burial rate required the determination of organic carbon accumulation rate to the Baltic sediments and the carbon return flux from sediments to the water column. Results of both sediment and mass accumulation rates as well as profiles of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) were used. Sediment accumulation rates were based on 210Pb method validated by 137Cs measurements and ranged from 66 g m-2 yr-1 to 744 g m-2 yr-1 as regards mass accumulation rates and from 0.07 cm yr-1 to 0.25 cm yr-1 as regards linear accumulation rates. Carbon deposition to the Baltic sediments amounts to 1.955 ± 0.585 Tg m-2 yr-1, while 0.759 ± 0.020 g m-2 yr-1 of carbon returns from sediments to the water column. Thus the organic carbon burial rate in the Baltic Sea sediments is equal to 1.197 ± 0.584 Tg C m-2 yr-1.

  6. Continuously accelerating ice loss over Amundsen Sea catchment, West Antarctica, revealed by integrating altimetry and GRACE data

    NASA Astrophysics Data System (ADS)

    Lee, Hyongki; Shum, C. K.; Howat, Ian M.; Monaghan, Andrew; Ahn, Yushin; Duan, Jianbin; Guo, Jun-Yi; Kuo, Chung-Yen; Wang, Lei

    2012-03-01

    Satellite altimetry and Gravity Recovery and Climate Experiment (GRACE) measurements have provided contemporary, but substantially different Antarctic ice sheet mass balance estimates. Altimetry provides no information about firn density while GRACE data is significantly impacted by poorly constrained glacial isostatic adjustment signals. Here, we combine Envisat radar altimetry and GRACE data over the Amundsen Sea (AS) sector, West Antarctica, to estimate the basin-wide averaged snow and firn column density over a seasonal time scale. Removing the firn variability signal from Envisat-observed ice-sheet elevation changes reveals more rapid dynamic thinning of underlying ice. We report that the net AS sector mass change rates are estimated to be - 47 ± 8 Gt yr- 1 between 2002 and 2006, and - 80 ± 4 Gt yr- 1 between2007 and 2009, equivalent to a sea level rise of 0.13 and 0.22 mm yr- 1, respectively. The acceleration is due to a combination of decreased snowfall accumulation (+ 13 Gt yr- 1 in 2002-2006, and - 6 Gt yr- 1 in 2007-2009) and enhanced ice dynamic thinning (- 60 ± 10 Gt yr- 1 in 2002-2006, and - 74 ± 11 Gt yr- 1 in 2007-2009) after 2007. Because there is no significant snowfall trend over the past 21 yr (1989-2009) and an increase in ice flow speed (2003-2010), the accelerated mass loss is likely to continue.

  7. 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.

  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. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Riparian Ecosystem Management at Military Installations: Determination of Impacts and Evaluation of Restoration and Enhancement Strategies

    DTIC Science & Technology

    2007-06-01

    rates near 0.2 cm yr-1 and an equilibrium response appeared to be reached near 0.5 cm yr-1. Nutrient contents of litterfall followed a similar pattern ... litterfall , and f) woody productivity from 2002-2006……………………………………………………… 8 Figure 2. Fine root biomass (0.1-1.0 mm diameter) through time...observed in LAI, BNPP, litterfall , microbial biomass, and community diversity with current sedimentation rates between 0.3 and 0.4 cm yr-1. Historical

  14. The Central Region in M100: Observations and Modeling

    NASA Astrophysics Data System (ADS)

    Knapen, J. H.; Beckman, J. E.; Heller, C. H.; Shlosman, I.; de Jong, R. S.

    1995-12-01

    formed by the interaction of a pair of trailing and leading shocks in the vicinity of the inner ILR, both peaks being sites of SF; and (4) two additional zones of SF corresponding to gas compression maxima at the bar's minor axis, where the large-scale shocks start to curl and which are referred in the literature as "twin peaks." We argue further that the twisting of K isophotes in the neighborhood of the resonance region requires a population of red stars which are dynamically young and follow gas rather than stellar orbits, i.e., red supergiants At the same time, a substantial contribution from OB stars to the K light is expected within the inner kiloparsec and especially in the symmetric K peaks. We also conclude that NGC 4321 hosts a single stellar bar which fuels the starburst activity within the circumnuclear "ring" by channeling gas there at the median rate of ˜0.1-1 Msun yr-1.

  15. 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

  16. 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

  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 spectroscopic investigation of P Cygni. I. H and HeI lines.

    NASA Astrophysics Data System (ADS)

    Najarro, F.; Hillier, D. J.; Stahl, O.

    1997-10-01

    We present a detailed spectroscopic analysis of the H and Hei spectrum of the Luminous Blue Variable (LBV) P Cygni. The observational constraints for our investigation are given by the mean optical and near-IR spectra obtained by Stahl et al. (1993A&AS...99..167S) and published UV, optical, IR and radio continuum measurements of the star. Within the parameter domain of interest we have investigated how line strengths, line shapes and the emergent energy distribution behave as a function of stellar parameters such as temperature, luminosity, wind density, etc. The sensitivity of the H and Hei line profiles to model parameters allows a quantitative spectroscopic analysis of P Cygni to be performed. The derived parameters for P Cygni place it near a regime where two classes of models exist - those in which H remains fully ionized in the wind, and those in which H eventually recombines in the wind. The transition between the two classes of models is dramatic - a 5% change in luminosity or mass-loss is sufficient. The shape of the P Cygni absorption on the Hα profile and the radio variability indicates that H must recombine in P Cygni's wind. As for Wolf-Rayet (W-R) stars we find that we can generate a set of homologous models which are capable of explaining, within observational errors, the flux distribution and the line profiles equally well. Scaling relations for the homologous models have been determined, but to first order they have the same T_eff_ and the same wind density parameter (˙(M)/R_*_^1.5^). Consequently it is impossible to derive R_*_ from a spectroscopic analysis. Assuming R_*_=75Rsun_, the following stellar parameters for P Cygni are derived: L_*_=5.6x10^5^Lsun_; (T_eff_=1.82kK); n_He_/n_H_=0.3; ˙(M)=3.0x10^-5^Msun_/yr; Vinfinity_=185km/s; β=2.5 and log(g_eff_)=1.20. These imply a stellar distance of 1.7+/-0.1kpc, which is consistent with determinations in the literature. Continuum fluxes and the observed optical and near-infrared H and Hei line

  19. Large-Scale Structure of the Molecular Gas in Taurus Revealed by High Linear Dynamic Range Spectral Line Mapping

    NASA Astrophysics Data System (ADS)

    Goldsmith, Paul F.; Heyer, Mark; Narayanan, Gopal; Snell, Ronald; Li, Di; Brunt, Chris

    2008-06-01

    We report the results of a 100 deg2 survey of the Taurus molecular cloud region in 12CO and 13CO J = 1→ 0. The image of the cloud in each velocity channel includes simeq3 × 106 Nyquist-sampled pixels on a 20'' grid. The high sensitivity and large spatial dynamic range of the maps reveal a very complex, highly structured cloud morphology, including filaments, cavities, and rings. The axes of the striations seen in the 12CO emission from relatively diffuse gas are aligned with the direction of the magnetic field. We have developed a statistical method for analyzing the pixels in which 12CO but not 13CO is detected, which allows us to determine the CO column in the diffuse portion of the cloud, as well as in the denser regions in which we detect both isotopologues. Using a column-density-dependent model for the CO fractional abundance, we derive the mass of the region mapped to be 2.4 × 104 M⊙, more than twice as large as would be obtained using a canonical fixed fractional abundance of 13CO, and a factor of 3 greater than would be obtained considering only the high column density regions. We determine that half the mass of the cloud is in regions having column density below 2.1 × 1021 cm-2. The distribution of young stars in the region covered is highly nonuniform, with the probability of finding a star in a pixel with a specified column density rising sharply for N(H2) = 6 × 1021 cm-2. We determine a relatively low star formation efficiency (mass of young stars/mass of molecular gas), between 0.3% and 1.2%, and an average star formation rate during the past 3 Myr of 8 × 10-5 stars yr-1.

  20. Forming supermassive black hole seeds under the influence of a nearby anisotropic multifrequency source.

    PubMed

    Regan, John A; Johansson, Peter H; Wise, John H

    2016-07-01

    The photodissociation of H2 by a nearby anisotropic source of radiation is seen as a critical component in creating an environment in which a direct collapse black hole may form. Employing radiative transfer we model the effect of multifrequency (0.76-60 eV) radiation on a collapsing halo at high redshift. We vary both the shape of the spectrum which emits the radiation and the distance to the emitting galaxy. We use blackbody spectra with temperatures of T = 10(4) K and 10(5) K and a realistic stellar spectrum. We find that an optimal zone exists between 1 and 4 kpc from the emitting galaxy. If the halo resides too close to the emitting galaxy the photoionizing radiation creates a large H ii region which effectively disrupts the collapsing halo, too far from the source and the radiation flux drops below the level of the expected background and the H2 fraction remains too high. When the emitting galaxy is initially placed between 1 and 2 kpc from the collapsing halo, with a spectral shape consistent with a star-forming high-redshift galaxy, then a large central core forms. The mass of the central core is between 5000 and 10 000 M⊙ at a temperature of approximately 1000 K. This core is however surrounded by a reservoir of hotter gas at approximately 8000 K, which leads to mass inflow rates of the order of ∼0.1 M⊙ yr(-1).

  1. 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.

  2. Effects of lightning NOx production during the 21 July European Lightning Nitrogen Oxides Project storm studied with a three-dimensional cloud-scale chemical transport model

    NASA Astrophysics Data System (ADS)

    Ott, Lesley E.; Pickering, Kenneth E.; Stenchikov, Georgiy L.; Huntrieser, Heidi; Schumann, Ulrich

    2007-03-01

    The 21 July 1998 thunderstorm observed during the European Lightning Nitrogen Oxides Project (EULINOX) project was simulated using the three-dimensional Goddard Cumulus Ensemble (GCE) model. The simulation successfully reproduced a number of observed storm features including the splitting of the original cell into a southern cell which developed supercell characteristics and a northern cell which became multicellular. Output from the GCE simulation was used to drive an offline cloud-scale chemical transport model which calculates tracer transport and includes a parameterization of lightning NOx production which uses observed flash rates as input. Estimates of lightning NOx production were deduced by assuming various values of production per intracloud and production per cloud-to-ground flash and comparing the results with in-cloud aircraft observations. The assumption that both types of flashes produce 360 moles of NO per flash on average compared most favorably with column mass and probability distribution functions calculated from observations. This assumed production per flash corresponds to a global annual lightning NOx source of 7 Tg N yr-1. Chemical reactions were included in the model to evaluate the impact of lightning NOx on ozone. During the storm, the inclusion of lightning NOx in the model results in a small loss of ozone (on average less than 4 ppbv) at all model levels. Simulations of the chemical environment in the 24 hours following the storm show on average a small increase in the net production of ozone at most levels resulting from lightning NOx, maximizing at approximately 5 ppbv day-1 at 5.5 km. Between 8 and 10.5 km, lightning NOx causes decreased net ozone production.

  3. Photoevaporation of Circumstellar Disks Revisited: The Dust-free Case

    NASA Astrophysics Data System (ADS)

    Tanaka, Kei E. I.; Nakamoto, Taishi; Omukai, Kazuyuki

    2013-08-01

    Photoevaporation by stellar ionizing radiation is believed to play an important role in the dispersal of disks around young stars. The mass-loss model for dust-free disks developed by Hollenbach et al. is currently regarded as the conventional one and has been used in a wide variety of studies. However, the rate in this model was derived using the crude so-called 1+1D approximation of ionizing radiation transfer, which assumes that diffuse radiation propagates in a direction vertical to the disk. In this study, we revisit the photoevaporation of dust-free disks by solving the two-dimensional axisymmetric radiative transfer for steady-state disks. Unlike that solved by the conventional model, we determine that direct stellar radiation is more important than the diffuse field at the disk surface. The radial density distribution at the ionization boundary is represented by a single power law with index -3/2 in contrast to the conventional double power law. For this distribution, the photoevaporation rate from the entire disk can be written as a function of the ionizing photon emissivity ΦEUV from the central star and the disk outer radius r d as follows: \\dot{M}_PE = 5.4 \\times 10^{-5} (\\Phi _EUV/10^{49}\\ s^{-1})^{1/2} (r_d/1000\\ AU)^{1/2} \\ M_\\odot \\ yr^{-1}. This new rate depends on the outer disk radius rather than on the gravitational radius as in the conventional model, because of the enhanced contribution to the mass loss from the outer disk annuli. In addition, we discuss its applications to present-day as well as primordial star formation.

  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.

  5. A Hot and Massive Accretion Disk around the High-mass Protostar IRAS 20126+4104

    NASA Astrophysics Data System (ADS)

    Chen, Huei-Ru Vivien; Keto, Eric; Zhang, Qizhou; Sridharan, T. K.; Liu, Sheng-Yuan; Su, Yu-Nung

    2016-06-01

    We present new spectral line observations of the CH3CN molecule in the accretion disk around the massive protostar IRAS 20126+4104 with the Submillimeter Array, which, for the first time, measure the disk density, temperature, and rotational velocity with sufficient resolution (0.″37, equivalent to ˜600 au) to assess the gravitational stability of the disk through the Toomre-Q parameter. Our observations resolve the central 2000 au region that shows steeper velocity gradients with increasing upper state energy, indicating an increase in the rotational velocity of the hotter gas nearer the star. Such spin-up motions are characteristics of an accretion flow in a rotationally supported disk. We compare the observed data with synthetic image cubes produced by three-dimensional radiative transfer models describing a thin flared disk in Keplerian motion enveloped within the centrifugal radius of an angular-momentum-conserving accretion flow. Given a luminosity of 1.3 × 104 L ⊙, the optimized model gives a disk mass of 1.5 M ⊙ and a radius of 858 au rotating about a 12.0 M ⊙ protostar with a disk mass accretion rate of 3.9 × 10-5 M ⊙ yr-1. Our study finds that, in contrast to some theoretical expectations, the disk is hot and stable to fragmentation with Q > 2.8 at all radii which permits a smooth accretion flow. These results put forward the first constraints on gravitational instabilities in massive protostellar disks, which are closely connected to the formation of companion stars and planetary systems by fragmentation.

  6. A Multi-wavelength Investigation of RCW175: An H II Region Harboring Spinning Dust Emission

    NASA Astrophysics Data System (ADS)

    Tibbs, C. T.; Paladini, R.; Compiègne, M.; Dickinson, C.; Alves, M. I. R.; Flagey, N.; Shenoy, S.; Noriega-Crespo, A.; Carey, S.; Casassus, S.; Davies, R. D.; Davis, R. J.; Molinari, S.; Elia, D.; Pestalozzi, M.; Schisano, E.

    2012-08-01

    Using infrared, radio continuum, and spectral observations, we performed a detailed investigation of the H II region RCW175. We determined that RCW175, which actually consists of two separate H II regions, G29.1-0.7 and G29.0-0.6, is located at a distance of 3.2 ± 0.2 kpc. Based on the observations we infer that the more compact G29.0-0.6 is less evolved than G29.1-0.7 and was possibly produced as a result of the expansion of G29.1-0.7 into the surrounding interstellar medium. We compute a star formation rate for RCW175 of (12.6 ± 1.9) × 10-5 M ⊙ yr-1, and identified six possible young stellar object candidates within its vicinity. Additionally, we estimate that RCW175 contains a total dust mass of 215 ± 53 M ⊙. RCW175 has previously been identified as a source of anomalous microwave emission (AME), an excess of emission at centimeter wavelengths often attributed to electric dipole radiation from the smallest dust grains. We find that the AME previously detected in RCW175 is not correlated with the smallest dust grains (polycyclic aromatic hydrocarbons or small carbonaceous dust grains), but rather with the exciting radiation field within the region. This is a similar result to that found in the Perseus molecular cloud, another region which harbors AME, suggesting that the radiation field may play a pivotal role in the production of this new Galactic emission mechanism. Finally, we suggest that these observations may hint at the importance of understanding the role played by the major gas ions in spinning dust models.

  7. The central parsecs of M87: jet emission and an elusive accretion disc

    NASA Astrophysics Data System (ADS)

    Prieto, M. A.; Fernández-Ontiveros, J. A.; Markoff, S.; Espada, D.; González-Martín, O.

    2016-04-01

    We present the first simultaneous spectral energy distribution (SED) of M87 core at a scale of 0.4 arcsec ( ˜ 32 pc) across the electromagnetic spectrum. Two separate, quiescent, and active states are sampled that are characterized by a similar featureless SED of power-law form, and that are thus remarkably different from that of a canonical active galactic nuclei or a radiatively inefficient accretion source. We show that the emission from a jet gives an excellent representation of the core of M87 core covering ten orders of magnitude in frequency for both the active and the quiescent phases. The inferred total jet power is, however, one to two orders of magnitude lower than the jet mechanical power reported in the literature. The maximum luminosity of a thin accretion disc allowed by the data yields an accretion rate of < 6 × 10- 5 M⊙ yr- 1, assuming 10 per cent efficiency. This power suffices to explain M87 radiative luminosity at the jet frame, it is however two to three order of magnitude below that required to account for the jet's kinetic power. The simplest explanation is variability, which requires the core power of M87 to have been two to three orders of magnitude higher in the last 200 yr. Alternatively, an extra source of power may derive from black hole spin. Based on the strict upper limit on the accretion rate, such spin power extraction requires an efficiency an order of magnitude higher than predicted from magnetohydrodynamic simulations, currently in the few hundred per cent range.

  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. Magnetic launching and collimation of jets from the disc-magnetosphere boundary: 2.5D MHD simulations

    NASA Astrophysics Data System (ADS)

    Lii, Patrick; Romanova, Marina; Lovelace, Richard

    2012-03-01

    We use axisymmetric magnetohydrodynamic simulations to investigate the launching and collimation of jets emerging from the disc-magnetosphere boundary of accreting magnetized stars. Our analysis shows that the matter flows into the jet from the inner edge of the accretion disc. It is magnetically accelerated along field lines extending up from the disc and simultaneously collimated by the magnetic pinch force. In the reference run which we use for analysis, the matter in the jet crosses the Alfvén surface a few R* above the disc and the fast magnetosonic surface ˜13R* above the disc. At larger distances, the magnetic pressure is a few times smaller than the total matter pressure, but the magnetic force continues to accelerate and collimate the jet. In steady state, we observe a matter ejection-to-accretion ratio of ˜0.2. Across different simulation runs, we measure a range of half-opening angles between Θ≈ 4° and 20° at the top of the simulation region, depending on the degree of magnetization in the outflow. We consider the case of stars undergoing epochs of high accretion [such as EX Lupi (EXors), FU Orionis (FUORs) and Classical T Tauri Stars (CTTSs)] where the stellar magnetosphere is strongly compressed by the incoming accretion disc. For a typical EXor (mass 0.8 M⊙, radius 2 R⊙) accreting at ˜10-5 M⊙ yr-1, we measure poloidal velocities in the jet ranging from 30 km s-1 on the outer edge of the jet to more than 260 km s-1 on the inner edge. In general, the models can be applied to a variety of magnetized stars - white dwarfs, neutron stars and brown dwarfs - which exhibit periods of high accretion.

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

    NASA Astrophysics Data System (ADS)

    Garnavich, P. M.; Tucker, B. E.; Rest, A.; Shaya, E. J.; Olling, R. P.; Kasen, D.; Villar, A.

    2016-03-01

    We discovered two transient events in the Kepler field with light curves that strongly suggest they are type II-P supernovae (SNe II-P). 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. Based on fits to idealized analytic models, 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 shock wave moving into pre-existing wind or mass-loss from the RSG. A mass-loss rate of 10-4M⊙ 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 SNe II-P.

  11. 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.

  12. First firm spectral classification of an early-B pre-main-sequence star: B275 in M 17

    NASA Astrophysics Data System (ADS)

    Ochsendorf, B. B.; Ellerbroek, L. E.; Chini, R.; Hartoog, O. E.; Hoffmeister, V.; Waters, L. B. F. M.; Kaper, L.

    2011-12-01

    The optical to near-infrared (300 - 2500 nm) spectrum of the candidate massive young stellar object (YSO) B275, embedded in the star-forming region M 17, has been observed with X-shooter on the ESO Very Large Telescope. The spectrum includes both photospheric absorption lines and emission features (H and Ca ii triplet emission lines, 1st and 2nd overtone CO bandhead emission), as well as an infrared excess indicating the presence of a (flaring) circumstellar disk. The strongest emission lines are double-peaked with a peak separation ranging between 70 and 105 km s-1, and they provide information on the physical structure of the disk. The underlying photospheric spectrum is classified as B6-B7, which is significantly cooler than a previous estimate based on modeling of the spectral energy distribution. This discrepancy is solved by allowing for a larger stellar radius (i.e. a bloated star) and thus positioning the star above the main sequence. This constitutes the first firm spectral classification of an early-B pre-main-sequence (PMS) star. We discuss the position of B275 in the Hertzsprung-Russell diagram in terms of PMS evolution. Although the position is consistent with PMS tracks of heavily accreting protostars (Ṁacc ≳ 10-5 M⊙ yr-1), the fact that the photosphere of the object is detectable suggests that the current mass-accretion rate is not very high. Based on observations performed with the ESO Very Large Telescope on Cerro Paranal, Chile, as part of the X-shooter Science Verification program 60.A-9402(A).

  13. Quantifying the contribution of glacier meltwater in the expansion of the largest lake in Tibet

    NASA Astrophysics Data System (ADS)

    Tong, Kai; Su, Fengge; Xu, Baiqing

    2016-10-01

    Lake Siling Co is currently the largest endorheic lake in Tibet, and the lake surface area has expanded by about 40% since the 1970s, with a remarkable acceleration after 1999. In this study, a hydrologic modeling framework was established by linking the Variable Infiltration Capacity (VIC) land surface hydrologic model with the degree-day glacier-melt model over the Lake Siling Co basin, with an aim to quantify the contribution of each runoff component to changes in the lake storage. We found that glacier melt contributed to less than 10% of the total water input to the lake during 1979-2013, while precipitation-induced runoff in nonglacierized area was responsible for about 67-75%. The mean annual water input to the lake increased by 2.15 × 109 m3 yr-1 in 2000-2013 relative to that in 1979-1999. The amount of precipitation over the lake surface, precipitation-induced runoff, and glacier-melt runoff accounted for 13%, 82%, and 5% of this total increase, respectively, suggesting that the substantial expansion of Siling Co in the 2000s was mostly due to the increase in precipitation-induced runoff. When modeling lake level changes during 1979-2013, we found that the water level rose by 14.1 m when glacier melt was included and by only 10.5 m, a reduction of about one fourth, when glacier melt was removed. It is concluded that glacier melt played an important role in controlling the water level of Siling Co, although it only contributed less than 10% of water input to the lake during 1979-2013.

  14. 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).

  15. Stagnant Shells in the Vicinity of the Dusty Wolf-Rayet-O/B Binary WR 112

    NASA Astrophysics Data System (ADS)

    Lau, Ryan M.; Hankins, Matthew; Schoedel, R.; Sanchez-Bermudez, Joel; Moffat, Anthony F. J.; Ressler, Michael E.

    2017-01-01

    We present high spatial resolution mid-infrared images of the nebula around the late-type carbon-rich Wolf-Rayet (WC)-O/B binary system WR 112 taken by the recently upgraded VLT spectrometer and imager for the mid-infrared (VISIR) with the PAH1, NeII_2, and Q3 filters. The observations reveal a morphology resembling a series of arc-like filaments and broken shells. Dust temperatures and masses are derived for each of the identified filamentary structures, which exhibit temperatures ranging from 179 ± 8 K at the exterior W2 filament to 355 ± 37 K in the central 3''. The total dust mass summed over all the features is 2.6 ± 0.4 × 10-5 M⊙. A multi-epoch analysis of previous mid-IR photometry of WR 112 over the past ~20 yr reveals no significant variability in the observed dust temperature and mass. The morphology of the mid-IR dust emission from WR 112 also exhibits no significant expansion between archival imaging data taken in 2007 May 7, which disputes the current interpretation of the nebula as a high expansion velocity (~1200 km s-1) "pinwheel"-shaped outflow driven by the colliding winds of the central WC-O/B system. An upper limit of <120 km s-1 is derived for the expansion velocity assuming a distance of 4.15 kpc. The upper limit on the average mass-loss rate from the central 3'' of WR 112 is estimated to be < 8 × 10-6 M⊙ yr-1. Based on these constraints, we suggest that the WR 112 nebula formed in the slow, dense outflow during a previous red supergiant (RSG) phase of the central Wolf-Rayet star.

  16. HST Emission Line Galaxies at z ~ 2: Comparing Physical Properties of Lyman Alpha and Optical Emission Line Selected Galaxies

    NASA Astrophysics Data System (ADS)

    Hagen, Alex; Zeimann, Gregory R.; Behrens, Christoph; Ciardullo, Robin; Grasshorn Gebhardt, Henry S.; Gronwall, Caryl; Bridge, Joanna S.; Fox, Derek B.; Schneider, Donald P.; Trump, Jonathan R.; Blanc, Guillermo A.; Chiang, Yi-Kuan; Chonis, Taylor S.; Finkelstein, Steven L.; Hill, Gary J.; Jogee, Shardha; Gawiser, Eric

    2016-01-01

    We compare the physical and morphological properties of z ˜ 2 Lyα emitting galaxies (LAEs) identified in the HETDEX Pilot Survey and narrow band studies with those of z ˜ 2 optical emission line selected galaxies (oELGs) identified via HST WFC3 infrared grism spectroscopy. Both sets of galaxies extend over the same range in stellar mass (7.5\\lt {log}M/{M}⊙ \\lt 10.5), size (0.5 < R < 3.0 kpc), and star formation rate (˜ 1\\lt {{SFR}}\\lt 100 {M}⊙ yr-1). Remarkably, a comparison of the most commonly used physical and morphological parameters—stellar mass, half-light radius, UV slope, SFR, ellipticity, nearest neighbor distance, star formation surface density, specific SFR, [O iii] luminosity, and [O iii] equivalent width—reveals no statistically significant differences between the populations. This suggests that the processes and conditions which regulate the escape of Lyα from a z ˜ 2 star-forming galaxy do not depend on these quantities. In particular, the lack of dependence on the UV slope suggests that Lyα emission is not being significantly modulated by diffuse dust in the interstellar medium. We develop a simple model of Lyα emission that connects LAEs to all high-redshift star-forming galaxies where the escape of Lyα depends on the sightline through the galaxy. Using this model, we find that mean solid angle for Lyα escape is {{{Ω }}}{{Ly}α }=2.4+/- 0.8 steradians; this value is consistent with those calculated from other studies.

  17. SINFONI-HiZELS: the dynamics, merger rates and metallicity gradients of 'typical' star-forming galaxies at z = 0.8-2.2

    NASA Astrophysics Data System (ADS)

    Molina, J.; Ibar, Edo; Swinbank, A. M.; Sobral, D.; Best, P. N.; Smail, I.; Escala, A.; Cirasuolo, M.

    2017-04-01

    We present adaptive optics (AO) assisted SINFONI integral field unit (IFU) spectroscopy of 11 Hα emitting galaxies selected from the High-Z Emission Line Survey (HiZELS). We obtain spatially resolved dynamics on ∼kpc-scales of star-forming galaxies [stellar mass M⋆ = 109.5 - 10.5 M⊙ and star formation rate (SFR) = 2-30 M⊙ yr-1] near the peak of the cosmic star formation rate history. Combining these observations with our previous SINFONI-HiZELS campaign, we construct a sample of 20 homogeneously selected galaxies with IFU AO-aided observations - the 'SHiZELS' survey, with roughly equal number of galaxies per redshift slice, at z = 0.8, 1.47 and 2.23. We measure the dynamics and identify the major kinematic axis by modelling their velocity fields to extract rotational curves and infer their inclination-corrected rotational velocities. We explore the stellar mass Tully-Fisher relationship, finding that galaxies with higher velocity dispersions tend to deviate from this relation. Using kinemetry analyses, we find that galaxy interactions might be the dominant mechanism controlling the star formation activity at z = 2.23 but they become gradually less important down to z = 0.8. Metallicity gradients derived from the [N II]/Hα emission line ratio show a median negative gradient for the SHiZELS survey of Δlog(O/H)/ΔR = -0.026 ± 0.008 dex kpc-1. We find that metal-rich galaxies tend to show negative gradients, whereas metal-poor galaxies tend to exhibit positive metallicity gradients. This result suggests that the accretion of pristine gas in the periphery of galaxies plays an important role in replenishing the gas in 'typical' star-forming galaxies.

  18. 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.

  19. 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.

  20. 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

  1. 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%.

  2. Marine erosion rates and coastal morphology of reef limestones on Grand Cayman Island, West Indies

    NASA Astrophysics Data System (ADS)

    Spencer, Tom

    1985-09-01

    Direct measurements of surface lowering, using the micro-erosion meter technique, have been obtained from Pleistocene and Tertiary limestones in subtidal and intertidal environments on Grand Cayman Island, West Indies. Overall, erosion rates averaged 0.99 mm yr-1; however this figure conceals the fact that the mean erosion rate on open coasts (X=2.77 mm yr-1) was over six times greater than the rate on reef-protected shores (X=0.45 mm yr-1). On lagoonal rocky coasts abrasion and biological action appear to be the dominant erosional processes, but on coasts exposed to high wave surf, bioconstruction dominates over bio-erosion and surface erosion is slight (X=0.17 mm yr-1). Thus, the magnitude and relative importance of physical, chemical and biological erosion processes differ from one locality to the next with variations in coastal exposure and between reef areas with changes in tidal range and wave regime.

  3. Sulphur and nitrogen fluxes and budgets in the Bohemian Forest and Tatra Mountains during the Industrial Revolution (1850-2000)

    NASA Astrophysics Data System (ADS)

    Kopcek, J.; Vesel, J.; Stuchlk, E.

    Major fluxes of sulphur and dissolved inorganic nitrogen were estimated in Central European mountain ecosystems of the Bohemian Forest (forest lakes) and Tatra Mountains (alpine lakes) over the industrial period. Sulphur outputs from these ecosystems were comparable to inputs during a period of relatively stable atmospheric deposition (10-35 mmol m-2 yr-1) around the 1930s. Atmospheric inputs of sulphur increased by three- to four-fold between the 1950s and 1980s to ~140 and ~60 mmol mm-2 yr-1 in the Bohemian Forest and Tatra Mountains, respectively. Sulphur outputs were lower than inputs due to accumulation in soils, which was higher in forest soils than in the sparser alpine soils and represented 0.8-1.6 and 0.2-0.3 mol m-2, respectively, for the whole 1930-2000 period. In the 1990s, atmospheric inputs of sulphur decreased 80% and 50% in the Bohemian Forest and Tatra Mountains, respectively, and sulphur outputs exceeded inputs. Catchment soils became pronounced sources of sulphur with output fluxes averaging between 15 and 31 mmol m-2 yr-1. Higher sulphur accumulation in the forest soils has delayed (by several decades) recovery of forest lakes from acidification compared to alpine lakes. Estimated deposition of dissolved inorganic nitrogen was 53-75 mmol m-2 yr-1 in the Bohemian Forest and 35-45 mmol m-2 yr-1 in the Tatra Mountains in the 1880- 1950 period, i.e. below the empirically derived threshold of ~70 mmol m-2 yr-1, above which nitrogen leaching often occurs. Dissolved inorganic nitrogen was efficiently retained in the ecosystems and nitrate export was negligible (0-7 mmol m-2 yr-1). By the 1980s, nitrogen deposition increased to ~160 and ~80 mmol m-2 yr-1 in the Bohemian Forest and Tatra Mountains, respectively, and nitrogen output increased to 120 and 60 mmol m-2 yr-1. Moreover, assimilation of nitrogen in soils declined from ~40 to 10-20 mmol m-2 yr-1 in the alpine soils and even more in the Bohemian Forest, where one of the catchments has even become

  4. 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.

  5. Comparison of soil greenhouse gas fluxes from extensive and intensive grazing in a temperate maritime climate

    NASA Astrophysics Data System (ADS)

    Skiba, U.; Jones, S. K.; Drewer, J.; Helfter, C.; Anderson, M.; Dinsmore, K.; McKenzie, R.; Nemitz, E.; Sutton, M. A.

    2013-02-01

    Greenhouse gas (GHG) fluxes from a seminatural, extensively sheep-grazed drained moorland and intensively sheep-grazed fertilised grassland in South East (SE) Scotland were compared over 4 yr (2007-2010). Nitrous oxide (N2O) and methane (CH4) fluxes were measured by static chambers, respiration from soil plus ground vegetation by a flow-through chamber, and the net ecosystem exchange (NEE) of carbon dioxide (CO2) by eddy-covariance. All GHG fluxes displayed high temporal and interannual variability. Temperature, radiation, water table height and precipitation could explain a significant percentage of seasonal and interannual variations. Greenhouse gas fluxes were dominated by the net ecosystem exchange of CO2 at both sites. Net ecosystem exchange of CO2 and respiration was much larger on the productive fertilised grassland (-1567 and 7157 g CO2eq m-2 yr-1, respectively) than on the seminatural moorland (-267 and 2554 g CO2eq m-2 yr-1, respectively). Large ruminant CH4 (147 g CO2eq m-2 yr-1) and soil N2O (384 g CO2eq m-2 yr-1) losses from the grazed grassland counteracted the CO2 uptake by 34%, whereas the small N2O (0.8 g CO2eq m-2 yr-1) and CH4 (7 g CO2eq m-2 yr-1) emissions from the moorland only impacted the NEE flux by 3%. The 4-yr average GHG budget for the grazed grassland was -1034 g CO2eq m-2 yr-1 and -260 g CO2eq m-2 yr-1 for the moorland.

  6. 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.

  7. 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.

  8. Water budget and vertical conductance for Lowry (Sand Hill) Lake in north-central Florida, USA

    NASA Astrophysics Data System (ADS)

    Motz, Louis H.; Sousa, Gregory D.; Annable, Michael D.

    2001-09-01

    Water-budget components and the vertical conductance were determined for Lowry (Sand Hill) Lake in north-central Florida, USA. In this type of lake, which interacts with both the surface-water and groundwater systems, the inflow components are precipitation, surface-water inflow, groundwater inflow, and direct runoff (i.e. overland flow), and the outflow components are evaporation, groundwater outflow, and surface-water outflow. In a lake and groundwater system that is typical of many karst lakes in Florida, a large part of the groundwater outflow occurs by means of vertical leakage through an underlying confining unit to a deeper, highly transmissive aquifer called the upper Floridan aquifer. The water-budget component that represents vertical leakage to the upper Floridan aquifer was calculated as a residual using the water-budget equation. For the 13 month period from August 1994 to August 1995, relative to the surface area of the lake, rainfall at Lowry Lake was 1.55 m yr -1, surficial aquifer inflow was 0.79 m yr -1, surface-water inflow was 1.92 m yr -1, and direct runoff was 0.01 m yr -1. Lake evaporation was 1.11 m yr -1, and surface-water outflow was 1.61 m yr -1. The lake stage increased 0.07 m yr -1, and the vertical leakage to the upper Floridan aquifer was 1.48 m yr -1. Surficial aquifer outflow from the lake was negligible. At Lowry Lake, vertical leakage is a major component of the water budget, comprising about 35% of the outflow during the study period. The vertical conductance ( KV/ b), a coefficient that represents the average of the vertical conductances of the hydrogeologic units between the bottom of a lake and the top of the upper Floridan aquifer, was determined to be 2.51 × 10 -4 day -1 for Lowry Lake.

  9. Reduction in NO(x) emission trends over China: regional and seasonal variations.

    PubMed

    Gu, Dasa; Wang, Yuhang; Smeltzer, Charles; Liu, Zhen

    2013-11-19

    We analyzed satellite observations of nitrogen dioxide (NO2) columns by the Ozone Monitoring Instrument (OMI) over China from 2005 to 2010 in order to estimate the top-down anthropogenic nitrogen oxides (NOx) emission trends. Since NOx emissions were affected by the economic slowdown in 2009, we removed one year of abnormal data in the analysis. The estimated average emission trend is 4.01 ± 1.39% yr(-1), which is slower than the trend of 5.8-10.8% yr(-1) reported for previous years. We find large regional, seasonal, and urban-rural variations in emission trends. The average NOx emission trend of 3.47 ± 1.07% yr(-1) in warm season (June-September) is less than the trend of 5.03 ± 1.92% yr(-1) in cool season (October-May). The regional annual emission trends decrease from 4.76 ± 1.61% yr(-1) in North China Plain to 3.11 ± 0.98% yr(-1) in Yangtze River Delta and further down to -4.39 ± 1.81% yr(-1) in Pearl River Delta. The annual emission trends of the four largest megacities, Shanghai, Beijing, Guangzhou, and Shenzhen are -0.76 ± 0.29%, 0.69 ± 0.27%, -4.46 ± 1.22%, and -7.18 ± 2.88% yr(-1), considerably lower than the regional averages or surrounding rural regions. These results appear to suggest that a number of factors, including emission control measures of thermal power plants, increased hydro-power usage, vehicle emission regulations, and closure or migration of high-emission industries, have significantly reduced or even reversed the increasing trend of NOx emissions in more economically developed megacities and southern coastal regions, but their effects are not as significant in other major cities or less economically developed regions.

  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. 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-...

  12. 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.

  13. 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

    2005-09-01

    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, N(2)O and NO emissions, and nitrate leaching from the root zone. Global NH(3)-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 N(2)O-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).

  14. 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).

  15. Nutrient cycling at the sediment-water interface and in sediments at Chiricahueto marsh: a subtropical ecosystem associated with agricultural land uses.

    PubMed

    Soto-Jimenez, M F; Paez-Osuna, F; Bojorquez-Leyva, H

    2003-02-01

    A study was conducted to examine the potential role to accumulate and transform nitrogen and phosphorus of a common wetland type marsh; the site is located in a subtropical environment that receives agricultural pollutants. Chiricahueto marsh effectively removes N and P from surface waters. It is clear that the diagenetic processes are mainly controlled by the exponential decomposition of organic matter that takes place at the sediment-water interface and in the sedimentary column, under oxic and suboxic-anoxic conditions, respectively. Mass balances indicated a net sedimentation of 11.3 g Nm(-2)x yr (-1) and 3.9 g Pm(-2) x yr (-1), which results in an annual regeneration of 1.7 g Nm(-2) and 0.8 g Pm(-2) at the sediment-water interface under oxic conditions. A major remineralization rate was estimated in 6.4 g Nm(-2) x yr (-1) and 1.1g Pm(-2) x yr (-1) into the sedimentary column where suboxic to anoxic conditions occur by the utilization of nitrate, Fe and Mn as electron acceptors. The estimated burial fluxes in the deeper sediments (>50 cm) were 1.5 g Nm(-2) x yr (-1) and 0.4 g Pm(-2) x yr (-1).

  16. 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

  17. Imaging spectroscopy studies of Hawaiian ecosystems, carbon properties, and disturbance

    NASA Astrophysics Data System (ADS)

    Asner, Gregory P.; Vitousek, Peter M.

    2005-01-01

    The Hawaiian Islands contain more than two-thirds of the global life zones delineated by Holdridge1. We used high-fidelity imaging spectroscopy and shortwave-infrared (SWIR) spectral mixture analysis to analyze the lateral distribution of plant tissues and bare substrate across bioclimatic gradients and ecological life zones in Hawai'i. Unique quantities of photosynthetic and non-photosynthetic vegetation (PV, NPV) and bare substrate identified fundamental differences in ecosystem structure across life zones. There was a nearly 20-fold increase in PV fractional cover with a 10-fold increase in mean annual precipitation (< 250 to 2000 mm yr-1). NPV fractional cover remained nearly constant at ~50% in ecosystems with a mean annual precipitation < 1500 mm yr-1. Thereafter, NPV steadily declined to a minimum of ~ 20% at 3000 mm yr-1 of rainfall. Bare substrate fractions were highest (~50%) at precipitation levels < 750 mm yr-1, then declined to < 20% in the 750-1000 mm yr-1 zones. The combination of low bare substrate and high NPV cover in the 750-1000 mm yr-1 rainfall zones identified these areas as high fire risk. The results verify the applicability of SWIR imaging spectroscopy for ecosystem research on a global scale. They also set the framework for continued studies of ecosystem structure, function and invasive species throughout the Hawaiian Archipelago.

  18. 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.

  19. 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

  20. 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

  1. Atmospheric nutrient deposition to the west coast of South Africa

    NASA Astrophysics Data System (ADS)

    Nyaga, Justine M.; Cramer, Michael D.; Neff, Jason C.

    2013-12-01

    Atmospheric deposition is an important source of nutrients to many ecosystems, but is of particular importance to plant nutrition in areas where nutrients are scarce. Nutrient containing aerosols enter the atmosphere through industrial and agricultural activities, wildfires, and the production of terrigenous and marine aerosols. In this study, we collected bulk rain precipitation along the Atlantic coast of South Africa in a coastal “strandveld” vegetation region. This region is relatively remote from significant anthropogenic influences and is downwind of a highly productive and stormy portion of the Atlantic. Samples were collected over 12 months at sites along a 17 km downwind transect from the shoreline and analyzed for N, P, Na, Ca, Mg and K. Annual total N and total P fluxes of 4.8 kg ha-1 yr-1 and 0.16 kg ha-1 yr-1 are low compared to global averages. In contrast, fluxes of Na were 88.7 kg ha-1 yr-1, 16.2 kg ha-1 yr-1 for Ca, 12.1 kg ha-1 yr-1 for Mg and 5.2 kg ha-1 yr-1 for K; rates that are higher than most other measurements elsewhere in the world. Dissolved organic N represented ca. 71% of the N flux while 43% of the P flux was in the form of soluble reactive P (SRP). These results combined with the high fluxes of Na and Mg strongly suggest that marine aerosols are important contributors to nutrient deposition at this site.

  2. 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.

  3. Global mercury emissions to the atmosphere from anthropogenic and natural sources

    NASA Astrophysics Data System (ADS)

    Pirrone, N.; Cinnirella, S.; Feng, X.; Finkelman, R. B.; Friedli, H. R.; Leaner, J.; Mason, R.; Mukherjee, A. B.; Stracher, G. B.; Streets, D. G.; Telmer, K.

    2010-07-01

    This paper provides an up-to-date assessment of global mercury emissions from anthropogenic and natural sources. On an annual basis, natural sources account for 5207 Mg of mercury released to the global atmosphere, including the contribution from re-emission processes, which are emissions of previously deposited mercury originating from anthropogenic and natural sources, and primary emissions from natural reservoirs. Anthropogenic sources, which include a large number of industrial point sources, are estimated to account for 2320 Mg of mercury emitted annually. The major contributions are from fossil-fuel fired power plants (810 Mg yr-1), artisanal small scale gold mining (400 Mg yr-1), non-ferrous metals manufacturing (310 Mg yr-1), cement production (236 Mg yr-1), waste disposal (187 Mg yr-1) and caustic soda production (163 Mg yr-1). Therefore, our current estimate of global mercury emissions suggests that the overall contribution from natural sources (primary emissions + re-emissions) and anthropogenic sources is nearly 7527 Mg per year, the uncertainty associated with these estimates are related to the typology of emission sources and source regions.

  4. Global mercury emissions to the atmosphere from anthropogenic and natural sources

    NASA Astrophysics Data System (ADS)

    Pirrone, N.; Cinnirella, S.; Feng, X.; Finkelman, R. B.; Friedli, H. R.; Leaner, J.; Mason, R.; Mukherjee, A. B.; Stracher, G. B.; Streets, D. G.; Telmer, K.

    2010-02-01

    This paper provides an up-to-date assessment of global mercury emissions from anthropogenic and natural sources. On an annual basis, natural sources account for 5207 Mg of mercury released to the global atmosphere, including the contribution from re-emission processes, which are emissions of previously deposited mercury originating from anthropogenic and natural sources, and primary emissions from natural reservoirs. Anthropogenic sources, which include a large number of industrial point sources, are estimated to account for 2320 Mg of mercury emitted annually. The major contributions are from fossil-fuel fired power plants (810 Mg yr-1), artisanal small scale gold mining (400 Mg yr-1), non-ferrous metals manufacturing (310 Mg yr-1), cement production (236 Mg yr-1), waste disposal (187 Mg yr-1) and caustic soda production (163 Mg yr-1). Therefore, our current estimate of global mercury emissions suggests that the overall contribution from natural sources (primary emissions+re-emissions) and anthropogenic sources is nearly 7527 Mg per year, the uncertainty associated with these estimates are related to the typology of emission sources and source regions.

  5. 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).

  6. 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.

  7. Decadal trends in global CO emissions as seen by MOPITT

    NASA Astrophysics Data System (ADS)

    Yin, Y.; Chevallier, F.; Ciais, P.; Broquet, G.; Fortems-Cheiney, A.; Pison, I.; Saunois, M.

    2015-12-01

    Negative trends of carbon monoxide (CO) concentrations are observed in the recent decade by both surface measurements and satellite retrievals over many regions of the globe, but they are not well explained by current emission inventories. Here, we analyse the observed CO concentration decline with an atmospheric inversion that simultaneously optimizes the two main CO sources (surface emissions and atmospheric hydrocarbon oxidations) and the main CO sink (atmospheric hydroxyl radical OH oxidation). Satellite CO column retrievals from Measurements of Pollution in the Troposphere (MOPITT), version 6, and surface observations of methane and methyl chloroform mole fractions are assimilated jointly for the period covering 2002-2011. Compared to the model simulation prescribed with prior emission inventories, trends in the optimized CO concentrations show better agreement with that of independent surface in situ measurements. At the global scale, the atmospheric inversion primarily interprets the CO concentration decline as a decrease in the CO emissions (-2.3 % yr-1), more than twice the negative trend estimated by the prior emission inventories (-1.0 % yr-1). The spatial distribution of the inferred decrease in CO emissions indicates contributions from western Europe (-4.0 % yr-1), the United States (-4.6 % yr-1) and East Asia (-1.2 % yr-1), where anthropogenic fuel combustion generally dominates the overall CO emissions, and also from Australia (-5.3 % yr-1), the Indo-China Peninsula (-5.6 % yr-1), Indonesia (-6.7 % y-1), and South America (-3 % yr-1), where CO emissions are mostly due to biomass burning. In contradiction with the bottom-up inventories that report an increase of 2 % yr-1 over China during the study period, a significant emission decrease of 1.1 % yr-1 is inferred by the inversion. A large decrease in CO emission factors due to technology improvements would outweigh the increase in carbon fuel combustions and may explain this decrease. Independent

  8. Nitrous oxide emission inventory of German forest soils

    NASA Astrophysics Data System (ADS)

    Schulte-Bisping, Hubert; Brumme, Rainer; Priesack, Eckart

    2003-02-01

    Annual fluxes of N2O trace gas emissions were assessed after stratifying German forest soils into Seasonal Emission Pattern (SEP) and Background Emission Pattern (BEP). Broad-leaved forests with soil pH(KCl) ≤ 3.3 were assigned to have SEP, broad-leaved forests with soil pH(KCl) > 3.3 and all needle-leaved forests to have BEP. BEPs were estimated by a relationship between annual N2O emissions and carbon content of the O-horizon. SEPs were primarily controlled by temperature and moisture and simulated by the model Expert-N after calibration to a 9-year record of N2O measurements. Analysis with different climate and soil properties indicated that the model reacts highly sensitive to changes in soil temperature, soil moisture, and soil texture. A geographic information system (ARC/INFO) was used for a spatial resolution of 1 km × 1 km grid where land cover, dominant soil units, and hygro climate classes were combined. The mean annual N2O emission flux from German forest soils was estimated as 0.32 kg ha-1 yr-1. Broad-leaved forests with SEP had the highest emissions (2.05 kg ha-1 yr-1) followed by mixed forests (0.38 kg ha-1 yr-1), broad-leaved forests (0.37 kg ha-1 yr-1), and needle-leaved forests with BEP (0.17 kg ha-1 yr-1). The annual N2O emission from German forest soils was calculated as 3.26 Gg N2O-N yr-1. Although needle-leaved trees cover about 57% of the entire forest area in Germany, their contribution is low (0.96 Gg N2O-N yr-1). Broad-leaved forests cover about 22% of the forest area but have 55% higher emissions (1.49 Gg N2O-N yr-1) than needle-leaved. Mixed forests cover 21% of the area and contribute 0.81 Gg N2O-N yr-1. Compared to the total N2O emissions in Germany of 170 Gg N yr-1, forest soils contribute only 1.9%. However, there are some uncertainties in this emission inventory, which are intensely discussed.

  9. Overview of mercury dry deposition, litterfall, and throughfall studies

    NASA Astrophysics Data System (ADS)

    Wright, L. Paige; Zhang, Leiming; Marsik, Frank J.

    2016-10-01

    The current knowledge concerning mercury dry deposition is reviewed, including dry-deposition algorithms used in chemical transport models (CTMs) and at monitoring sites and related deposition calculations, measurement methods and studies for quantifying dry deposition of gaseous oxidized mercury (GOM) and particulate bound mercury (PBM), and measurement studies of litterfall and throughfall mercury. Measured median GOM plus PBM dry deposition in Asia (10.7 µg m-2 yr-1) is almost double that in North America (6.1 µg m-2 yr-1) due to the higher anthropogenic emissions in Asia. The measured mean GOM plus PBM dry deposition in Asia (22.7 µg m-2 yr-1), however, is less than that in North America (30.8 µg m-2 yr-1). The variations between the median and mean values reflect the influences that single extreme measurements can have on the mean of a data set. Measured median litterfall and throughfall mercury are, respectively, 34.8 and 49.0 µg m-2 yr-1 in Asia, 12.8 and 16.3 µg m-2 yr-1 in Europe, and 11.9 and 7.0 µg m-2 yr-1 in North America. The corresponding measured mean litterfall and throughfall mercury are, respectively, 42.8 and 43.5 µg m-2 yr-1 in Asia, 14.2 and 19.0 µg m-2 yr-1 in Europe, and 12.9 and 9.3 µg m-2 yr-1 in North America. The much higher litterfall mercury than GOM plus PBM dry deposition suggests the important contribution of gaseous elemental mercy (GEM) to mercury dry deposition to vegetated canopies. Over all the regions, including the Amazon, dry deposition, estimated as the sum of litterfall and throughfall minus open-field wet deposition, is more dominant than wet deposition for Hg deposition. Regardless of the measurement or modelling method used, a factor of 2 or larger uncertainties in GOM plus PBM dry deposition need to be kept in mind when using these numbers for mercury impact studies.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. Comparison of soil greenhouse gas fluxes from extensive and intensive grazing in a temperate maritime climate

    NASA Astrophysics Data System (ADS)

    Skiba, U.; Jones, S. K.; Drewer, J.; Helfter, C.; Anderson, M.; Dinsmore, K.; McKenzie, R.; Nemitz, E.; Sutton, M. A.

    2012-08-01

    Greenhouse gas (GHG) fluxes from a seminatural, extensively sheep grazed drained moorland and intensively sheep grazed fertilised grassland in SE Scotland were compared over 4 yr (2007-2010). Nitrous oxide and CH4 fluxes were measured by static chambers, respiration from soil including ground vegetation by a flow through chamber and the net ecosystem exchange of CO2 by eddy covariance. All GHG fluxes displayed high temporal and interannual variability. Temperature, radiation, water table height and precipitation could explain a significant percentage of seasonal and interannual variations. Greenhouse gas fluxes were dominated by the net ecosystem exchange of CO2, emissions of N2O from the grazed grassland (384 g CO2eq m-2 yr-1) and emissions of CH4 from ruminant fermentation (147 g CO2eq m-2 yr-1). Methane emissions from the moorland were small (6.7 g CO2eq m-2 yr-1). Net ecosystem exchange of CO2 and respiration were much larger on the productive fertilised grassland (-1624 and +7157 g CO2eq m-2 yr-1, respectively) than the seminatural moorland (-338 and +2554 g CO2eq m-2 yr-1, respectively). Large CH4 and N2O losses from the grazed grassland counteracted the CO2 uptake by 35%, whereas the small N2O and CH4 emissions from the moorland did only impact the NEE by 2%.The 4 yr average GHG budget for the grazed grassland was 1006 g CO2eq m-2 yr-1 and 331 g CO2eq m-2 yr-1 for the moorland.

  19. 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.

  20. Influence of Antarctic Intermediate Water on the deoxygenation of the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Santos, Guilherme Cordova; Kerr, Rodrigo; Azevedo, José Luiz Lima; Mendes, Carlos Rafael Borges; da Cunha, Letícia Cotrim

    2016-12-01

    Hydrographic trends in the Antarctic Intermediate Water (AAIW) layer that may be associated with changes in the thickness and oxygen content of oxygen minimum zones (OMZs) in the eastern tropical South Atlantic (ETSA) and eastern tropical North Atlantic (ETNA) are investigated by using historical data (1960 to 2015). Our results reveal that the thickness of these OMZs has continually increased (2.58 ± 0.67 m yr-1 for the ETSA and 3.37 ± 0.73 m yr-1 for the ETNA), the mean oxygen concentration has decreased (- 0.12 ± 0.03 μmol kg-1 yr-1 for the ETSA and - 0.17 ± 0.05 μmol kg-1 yr-1 for the ETNA), and the mean temperature has increased. The optimum multiparameter analysis method is used to track modifications in the AAIW along its path through the South Atlantic Subtropical Gyre. We observe an AAIW layer vertical expansion rate of 1.67 ± 0.71 m yr-1, a decrease in the mean oxygen concentration of - 0.18 ± 0.04 μmol kg-1 yr-1 and an increase in the mean temperature of 0.010 ± 0.005 °C yr-1. Moreover, a similar decrease in oxygen concentrations is observed in the AAIW layer of the studied OMZ regions compared to those in the non-AAIW portions of these OMZs, which indicates strong deoxygenation in this water mass over time. Our results suggest that warming in the AAIW source region and in its extensive temporal displacement through the SASG to the eastern tropical Atlantic Ocean appreciably shifted this water mass toward lower densities with depleted oxygen (increases in ventilation age and oxygen consumption). The warming trend that is reported here suggests that global warming is one of the factors that influence oxygen solubility changes during the deoxygenation and expansion of OMZs.

  1. 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.

  2. The VMC survey - XV. The Small Magellanic Cloud-Bridge connection history as traced by their star cluster populations

    NASA Astrophysics Data System (ADS)

    Piatti, Andrés E.; de Grijs, Richard; Rubele, Stefano; Cioni, Maria-Rosa L.; Ripepi, Vincenzo; Kerber, Leandro

    2015-06-01

    We present results based on YJKs photometry of star clusters located in the outermost, eastern region of the Small Magellanic Cloud (SMC). We analysed a total of 51 catalogued clusters whose colour-magnitude diagrams (CMDs), having been cleaned from field-star contamination, were used to assess the clusters' reality and estimate ages of the genuine systems. Based on CMD analysis, 15 catalogued clusters were found to be possible non-genuine aggregates. We investigated the properties of 80 per cent of the catalogued clusters in this part of the SMC by enlarging our sample with previously obtained cluster ages, adopting a homogeneous scale for all. Their spatial distribution suggests that the oldest clusters, log(t yr-1) ≥ 9.6, are in general located at greater distances to the galaxy's centre than their younger counterparts - 9.0 ≤ log(t yr-1) ≤ 9.4 - while two excesses of clusters are seen at log(t yr-1) ˜ 9.2 and log(t yr-1) ˜ 9.7. We found a trail of younger clusters which follow the wing/bridge components. This long spatial sequence does not only harbour very young clusters, log(t yr-1) ˜ 7.3, but it also hosts some of intermediate ages, log(t yr-1) ˜ 9.1. The derived cluster and field-star formation frequencies as a function of age are different. The most surprising feature is an observed excess of clusters with ages of log(t yr-1) < 9.0, which could have been induced by interactions with the LMC.

  3. Dissolved methane in the Beaufort Sea and the Arctic Ocean, 1992-2009; sources and atmospheric flux

    USGS Publications Warehouse

    Lorenson, Thomas D.; Greinert, Jens; Coffin, Richard B.

    2016-01-01

    Methane concentration and isotopic composition was measured in ice-covered and ice-free waters of the Arctic Ocean during eleven surveys spanning the years of 1992-1995 and 2009. During ice-free periods, methane flux from the Beaufort shelf varies from 0.14 to 0.43 mg CH4 m-2 day-1. Maximum fluxes from localized areas of high methane concentration are up to 1.52 mg CH4 m-2 day-1. Seasonal buildup of methane under ice can produce short-term fluxes of methane from the Beaufort shelf that varies from 0.28 to 1.01 to mg CH4 m-2 day-1. Scaled-up estimates of minimum methane flux from the Beaufort Sea and pan-Arctic shelf for both ice-free and ice-covered periods range from 0.02 Tg CH4 yr-1 and 0.30 Tg CH4 yr-1 respectively to maximum fluxes of 0.18 Tg CH4 yr-1 and 2.2 Tg CH4 yr-1 respectively. A methane flux of 0.36 Tg CH4 yr-1from the deep Arctic Ocean was estimated using data from 1993-94. The flux can be as much as 2.35 Tg CH4 yr-1 estimated from maximum methane concentrations and wind speeds of 12 m/s, representing only 0.42% of the annual atmospheric methane budget of ~560 Tg CH4 yr-1. There were no significant changes in methane fluxes during the time period of this study. Microbial methane sources predominate with minor influxes from thermogenic methane offshore Prudhoe Bay and the Mackenzie River delta and may include methane from gas hydrate. Methane oxidation is locally important on the shelf and is a methane sink in the deep Arctic Ocean.

  4. 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.

  5. 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/.

  6. Lower satellite-gravimetry estimates of Antarctic sea-level contribution.

    PubMed

    King, Matt A; Bingham, Rory J; Moore, Phil; Whitehouse, Pippa L; Bentley, Michael J; Milne, Glenn A

    2012-11-22

    Recent estimates of Antarctica's present-day rate of ice-mass contribution to changes in sea level range from 31 gigatonnes a year (Gt yr(-1); ref. 1) to 246 Gt yr(-1) (ref. 2), a range that cannot be reconciled within formal errors. Time-varying rates of mass loss contribute to this, but substantial technique-specific systematic errors also exist. In particular, estimates of secular ice-mass change derived from Gravity Recovery and Climate Experiment (GRACE) satellite data are dominated by significant uncertainty in the accuracy of models of mass change due to glacial isostatic adjustment (GIA). Here we adopt a new model of GIA, developed from geological constraints, which produces GIA rates systematically lower than those of previous models, and an improved fit to independent uplift data. After applying the model to 99 months (from August 2002 to December 2010) of GRACE data, we estimate a continent-wide ice-mass change of -69 ± 18 Gt yr(-1) (+0.19 ± 0.05 mm yr(-1) sea-level equivalent). This is about a third to a half of the most recently published GRACE estimates, which cover a similar time period but are based on older GIA models. Plausible GIA model uncertainties, and errors relating to removing longitudinal GRACE artefacts ('destriping'), confine our estimate to the range -126 Gt yr(-1) to -29 Gt yr(-1) (0.08-0.35 mm yr(-1) sea-level equivalent). We resolve 26 independent drainage basins and find that Antarctic mass loss, and its acceleration, is concentrated in basins along the Amundsen Sea coast. Outside this region, we find that West Antarctica is nearly in balance and that East Antarctica is gaining substantial mass.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. The IMF of Low-Mass Stars and Brown Dwarfs in Taurus

    NASA Astrophysics Data System (ADS)

    Luhman, K.

    2001-05-01

    By combining deep optical imaging and infrared spectroscopy with data from the Two-Micron All-Sky Survey (2MASS) and from previous studies, I have measured the Initial Mass Function (IMF) for a reddening-limited sample in four fields in the Taurus star forming region. This IMF is representative of the young populations within these fields for masses above 0.02 Msun. Relative to the similarly derived IMF for the Trapezium Cluster (Luhman et al.), the IMF for Taurus exhibits a modest deficit of stars above one solar mass (i.e., steeper slope), the same turnover mass (0.8 Msun), and a significant deficit of brown dwarfs. If the IMF in Taurus were the same as that in the Trapezium, 12.8+/-1.8 brown dwarfs (>0.02 Msun) are expected in these Taurus fields where only one brown dwarf candidate is found. These results are used to test theories of the IMF.

  13. Physical properties and evolution of the two white dwarfs in the Sanduleak-Pesch binary

    NASA Astrophysics Data System (ADS)

    Greenstein, J. L.; Dolez, N.; Vauclair, G.

    1983-10-01

    An important new binary white dwarf has been found by Sanduleak and Pesch. The stars are analyzed with the data from the Palomar double CCD spectrograph, using continuum fluxes, lines profiles, and Balmer decrements. They have hydrogen atmospheres, are young Population I, age ≈5×108 yr, temperatures of 12500K and 9500K, and the same visual magnitude. The cooler and less luminous star, B, has the larger radius and lower mass; B started its degenerate cooling, more recently, as the brighter of the pair. The estimated cooling times differ by approximately 108 yr. The white dwarfs, with masses 0.80 and 0.43 m_sun;, are descended from progenitors of 8 and 4 m_sun; (or 5 and 3.5 m_sun;).

  14. 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.

  15. 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

  16. Orbital Stability of the Hierarchical Triple System HIP 3678

    NASA Astrophysics Data System (ADS)

    Kirschbaum, Asher; Nordhaus, Jason

    2017-01-01

    HIP 3678 is a hierarchical triple system located in the center of planetary nebula (PN) NGC 246. The central star of the PN is a 0.84 M_sun PG 1159 star with a near-equal-mass K-dwarf companion and a recently discovered 0.1 M_sun tertiary companion at a projected separation of 500 AU. Using the highly-accurate, non-symplectic IAS15 integrator in REBOUND, we investigate the long-term stability of the system for scenarios consistent with current observational constraints on the orbital parameters.

  17. 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.

  18. Estimations of global no, emissions and their uncertainties

    NASA Astrophysics Data System (ADS)

    Lee, D. S.; Köhler, I.; Grobler, E.; Rohrer, F.; Sausen, R.; Gallardo-Klenner, L.; Olivier, J. G. J.; Dentener, F. J.; Bouwman, A. F.

    The AERONOX programme investigated the impact of NO x emissions from aircraft on the atmosphere and included an extensive modelling programme. In the model comparisons undertaken within the AERONOX programme, a "standard" set of emissions of NO x from both aviation and non-aviation sources was required so that differences between the models could be examined. This paper describes the data sets used in the study. These were: fossil fuel combustion from stationary and mobile sources at Earth's surface (22 Tg N yr -1), tropical biomass burning (5 Tg N yr -1), soil microbial production of NO (4 Tg N yr -1), lightning (5 Tg N yr -1), and the stratospheric decomposition of nitrous oxide (0.6 Tg N yr -1), ). However, global emission inventories of trace gases are developing rapidly: this paper also presents some emission estimates updated since the AERONOX study and also attempts to quantify uncertainties. The lightning source was constructed using convective cloud-top height from a GCM and differential rates of NO production calculated for cloud-to-cloud, and cloud-to-ground strikes. A revised biomass inventory including deforestation, savanna burning, agricultural waste burning and biofuel combustion results in approximately 8 Tg Nyr -1. This estimate includes sources beyond the tropics. Both extrapolation of measurements of soil NO fluxes by biome type, and a further refinement of the AERONOX soils emission model resulted in an emission of approximately 7 Tg Nyr -1. Ammonia oxidation as a source of NO x is calculated to be 0.9 N Tg yr -1), with a range of 0-l.6 Tg N yr -1), which shows that this is a relatively unimportant source of NO x in the troposphere. Uncertainty estimates for all sources have been given and discussed. The global source term for NO x for all sources (including the revisions) is estimated to be 44 Tg N yr -1), with an uncertainty range of 23-81 Tg N yr -1), A future scenario for fossil fuel combustion is given for 2025 resulting in an emission

  19. 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.

  20. 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.

  1. Litter and nutrient flows in tropical upland forest flooded by a hydropower plant in the Amazonian basin.

    PubMed

    Pereira, Guilherme Henrique A; Jordão, Henos Carlos K; Silva, Vanessa Francieli V; Pereira, Marcos Gervasio

    2016-12-01

    Extensive areas in the Brazilian Amazon have been flooded for the construction of hydroelectric dams. However, the water regime of these areas affects the dynamics of igarapés (streams) in adjacent terra firme (upland forests). When the reservoirs are filled, the water levels of streams rise above the normal levels and upland bank forests are flooded. We investigated how this flooding affects the litterfall and nutrient input in the upland forests upstream of a hydroelectric dam reservoir in the Central Amazonia. When the reservoir was filled, the forests were flooded and produced more than twice the litter (8.80Mg·ha(-1)yr(-1)), with three times more leaves (6.36Mg·ha(-1)yr(-1)) than when they were not flooded (4.20 and 1.92Mg·ha(-1)yr(-1), respectively). During flooding, the decomposition rate was four times lower in flooded forests (0.328g·g(-1)yr(-1)) than in control forests (1.460g·g(-1)yr(-1)). Despite this, the flooding did not favor litter or nutrient accumulation. Therefore, dam construction changes the organic matter and nutrient cycling in upland Amazon rainforests. This may influence the important role that they play in organic matter dynamics and could have consequences for the regional carbon balance and, ultimately, global climate.

  2. The Greenland Ice Sheet as a hot spot of phosphorus weathering and export in the Arctic

    NASA Astrophysics Data System (ADS)

    Hawkings, Jon; Wadham, Jemma; Tranter, Martyn; Telling, Jon; Bagshaw, Elizabeth; Beaton, Alexander; Simmons, Sarah-Louise; Chandler, David; Tedstone, Andrew; Nienow, Peter

    2016-02-01

    The contribution of ice sheets to the global biogeochemical cycle of phosphorus is largely unknown, due to the lack of field data. Here we present the first comprehensive study of phosphorus export from two Greenland Ice Sheet glaciers. Our results indicate that the ice sheet is a hot spot of phosphorus export in the Arctic. Soluble reactive phosphorus (SRP) concentrations, up to 0.35 µM, are similar to those observed in Arctic rivers. Yields of SRP are among the highest in the literature, with denudation rates of 17-27 kg P km-2 yr-1. Particulate phases, as with nonglaciated catchments, dominate phosphorus export (>97% of total phosphorus flux). The labile particulate fraction differs between the two glaciers studied, with significantly higher yields found at the larger glacier (57.3 versus 8.3 kg P km-2 yr-1). Total phosphorus yields are an order of magnitude higher than riverine values reported in the literature. We estimate that the ice sheet contributes ~15% of total bioavailable phosphorus input to the Arctic oceans (~11 Gg yr-1) and dominates total phosphorus input (408 Gg yr-1), which is more than 3 times that estimated from Arctic rivers (126 Gg yr-1). We predict that these fluxes will rise with increasing ice sheet freshwater discharge in the future.

  3. Modeling sustainable reuse of nitrogen-laden wastewater by poplar.

    PubMed

    Wang, Yusong; Licht, Louis; Just, Craig

    2016-01-01

    Numerical modeling was used to simulate the leaching of nitrogen (N) to groundwater as a consequence of irrigating food processing wastewater onto grass and poplar under various management scenarios. Under current management practices for a large food processor, a simulated annual N loading of 540 kg ha(-1) yielded 93 kg ha(-1) of N leaching for grass and no N leaching for poplar during the growing season. Increasing the annual growing season N loading to approximately 1,550 kg ha(-1) for poplar only, using "weekly", "daily" and "calculated" irrigation scenarios, yielded N leaching of 17 kg ha(-1), 6 kg ha(-1), and 4 kg ha(-1), respectively. Constraining the simulated irrigation schedule by the current onsite wastewater storage capacity of approximately 757 megaliters (Ml) yielded N leaching of 146 kg ha(-1) yr(-1) while storage capacity scenarios of 3,024 and 4,536 Ml yielded N leaching of 65 and 13 kg ha(-1) yr(-1), respectively, for a loading of 1,550 kg ha(-1) yr(-1). Further constraining the model by the current wastewater storage volume and the available land area (approximately 1,000 hectares) required a "diverse" irrigation schedule that was predicted to leach a weighted average of 13 kg-N ha(-1) yr(-1) when dosed with 1,063 kg-N ha(-1) yr(-1).

  4. The Uncertain Carbon Emissions in China (Invited)

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Guan, D.

    2013-12-01

    Anthropogenic fossil fuel emissions are considered as being well understood with a low uncertainty (9.1 × 0.5Gt C yr-1). By using full transparency emission inventory which the energy consumption, fuel heating values, carbon content and oxidation rate reported separately in sectoal level, here we found new 2.1 Gt C yr-1 (23% of global total) uncertainties of carbon emission inventory, which mainly contributed by the mass energy use and consumption coal quality in China and by misunderstanding of fuel quality in international fossil fuel trade. Increment of coal's carbon emission in China and India are equivalent to 130 % of global total coal's emission growth during 2008-2010, by using macro energy statistics and bottom up coal mine datasets, the difference carbon emission estimates from China and India can up to 1.32 C yr-1. Emissions from international trade of coal could produce another 0.08 Gt C yr-1 uncertainty. These new emerging 1.4 Gt C yr-1 uncertainties implies a significant mis-estimation of human induced carbon emissions and a new dominating factor in contributing the global carbon budget residual.

  5. Spatial and temporal Antarctic Ice Sheet mass trends, glacio-isostatic adjustment, and surface processes from a joint inversion of satellite altimeter, gravity, and GPS data.

    PubMed

    Martín-Español, Alba; Zammit-Mangion, Andrew; Clarke, Peter J; Flament, Thomas; Helm, Veit; King, Matt A; Luthcke, Scott B; Petrie, Elizabeth; Rémy, Frederique; Schön, Nana; Wouters, Bert; Bamber, Jonathan L

    2016-02-01

    We present spatiotemporal mass balance trends for the Antarctic Ice Sheet from a statistical inversion of satellite altimetry, gravimetry, and elastic-corrected GPS data for the period 2003-2013. Our method simultaneously determines annual trends in ice dynamics, surface mass balance anomalies, and a time-invariant solution for glacio-isostatic adjustment while remaining largely independent of forward models. We establish that over the period 2003-2013, Antarctica has been losing mass at a rate of -84 ± 22 Gt yr(-1), with a sustained negative mean trend of dynamic imbalance of -111 ± 13 Gt yr(-1). West Antarctica is the largest contributor with -112 ± 10 Gt yr(-1), mainly triggered by high thinning rates of glaciers draining into the Amundsen Sea Embayment. The Antarctic Peninsula has experienced a dramatic increase in mass loss in the last decade, with a mean rate of -28 ± 7 Gt yr(-1) and significantly higher values for the most recent years following the destabilization of the Southern Antarctic Peninsula around 2010. The total mass loss is partly compensated by a significant mass gain of 56 ± 18 Gt yr(-1) in East Antarctica due to a positive trend of surface mass balance anomalies.

  6. Complex forest dynamics indicate potential for slowing carbon accumulation in the southeastern United States

    NASA Astrophysics Data System (ADS)

    Coulston, John W.; Wear, David N.; Vose, James M.

    2015-01-01

    Over the past century forest regrowth in Europe and North America expanded forest carbon (C) sinks and offset C emissions but future C accumulation is uncertain. Policy makers need insights into forest C dynamics as they anticipate emissions futures and goals. We used land use and forest inventory data to estimate how forest C dynamics have changed in the southeastern United States and attribute changes to land use, management, and disturbance causes. From 2007-2012, forests yielded a net sink of C because of net land use change (+6.48 Tg C yr-1) and net biomass accumulation (+75.4 Tg C yr-1). Forests disturbed by weather, insect/disease, and fire show dampened yet positive forest C changes (+1.56, +1.4, +5.48 Tg C yr-1, respectively). Forest cutting caused net decreases in C (-76.7 Tg C yr-1) but was offset by forest growth (+143.77 Tg C yr-1). Forest growth rates depend on age or stage of development and projected C stock changes indicate a gradual slowing of carbon accumulation with anticipated forest aging (a reduction of 9.5% over the next five years). Additionally, small shifts in land use transitions consistent with economic futures resulted in a 40.6% decrease in C accumulation.

  7. 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.

  8. Spatial and temporal Antarctic Ice Sheet mass trends, glacio-isostatic adjustment, and surface processes from a joint inversion of satellite altimeter, gravity, and GPS data

    NASA Astrophysics Data System (ADS)

    Martín-Español, Alba; Zammit-Mangion, Andrew; Clarke, Peter J.; Flament, Thomas; Helm, Veit; King, Matt A.; Luthcke, Scott B.; Petrie, Elizabeth; Rémy, Frederique; Schön, Nana; Wouters, Bert; Bamber, Jonathan L.

    2016-02-01

    We present spatiotemporal mass balance trends for the Antarctic Ice Sheet from a statistical inversion of satellite altimetry, gravimetry, and elastic-corrected GPS data for the period 2003-2013. Our method simultaneously determines annual trends in ice dynamics, surface mass balance anomalies, and a time-invariant solution for glacio-isostatic adjustment while remaining largely independent of forward models. We establish that over the period 2003-2013, Antarctica has been losing mass at a rate of -84 ± 22 Gt yr-1, with a sustained negative mean trend of dynamic imbalance of -111 ± 13 Gt yr-1. West Antarctica is the largest contributor with -112 ± 10 Gt yr-1, mainly triggered by high thinning rates of glaciers draining into the Amundsen Sea Embayment. The Antarctic Peninsula has experienced a dramatic increase in mass loss in the last decade, with a mean rate of -28 ± 7 Gt yr-1 and significantly higher values for the most recent years following the destabilization of the Southern Antarctic Peninsula around 2010. The total mass loss is partly compensated by a significant mass gain of 56 ± 18 Gt yr-1 in East Antarctica due to a positive trend of surface mass balance anomalies.

  9. Assessment of the magnitude of ammonia emissions in the United Kingdom

    NASA Astrophysics Data System (ADS)

    Sutton, M. A.; Place, C. J.; Eager, M.; Fowler, D.; Smith, R. I.

    Estimates of ammonia emission in the U.K. have been critically reviewed with the aim of establishing the magnitude and uncertainty of each of the sources. European studies are also reviewed, with the U.K. providing a useful case study to highlight the uncertainties common to all ammonia emission inventories. This analysis of the emission factors and their application to U.K. sources supports an emission of 450 (231-715) Gg NH 3 yr -1. Agricultural activities are confirmed as the major source, providing 406 (215-630) Gg NH 3yr -1 (90% of the total), and therefore dominate uncertainties. Non-agricultural sources include sewage, pets, horses, humans, combustion and wild animals, though these contribute only 44 (16-85) Gg yr -1. Cattle represent the largest single uncertainty, accounting for 245 (119-389) Gg yr -1. The major uncertainties for cattle derive from estimation of the amount of nitrogen (N) excreted, the % N volatilized from land spreading of wastes, and the % N volatilized from stored farm-yard manure. Similar relative uncertainties apply to each of sheep, pigs and poultry, as well as fertilized crops, though these are quantitatively less important. Accounting; for regional differences in livestock demography, emission of 347, 63 and 40 Gg yr -1 are estimated for England & Wales, Scotland, and Northern Ireland, respectively. Though very uncertain, the total is in good agreement with estimates required to balance the U.K. atmospheric NH. budget.

  10. 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.

  11. Water resources trends in Middle East and North Africa towards 2050

    NASA Astrophysics Data System (ADS)

    Droogers, P.; Immerzeel, W. W.; Terink, W.; Hoogeveen, J.; Bierkens, M. F. P.; van Beek, L. P. H.; Debele, B.

    2012-09-01

    Changes in water resources availability can be expected as consequences of climate change, population growth, economic development and environmental considerations. A two-stage modeling approach is used to explore the impact of these changes in the Middle East and North Africa (MENA) region. An advanced, physically based, distributed, hydrological model is applied to determine the internal and external renewable water resources for the current situation and under future changes. Subsequently, a water allocation model is used to combine the renewable water resources with sectoral water demands. Results show that total demand in the region will increase to 393 km3 yr-1 in 2050, while total water shortage will grow to 199 km3 yr-1 in 2050 for the average climate change projection, an increase of 157 km3 yr-1. This increase in shortage is the combined impact of an increase in water demand by 50% with a decrease in water supply by 12%. Uncertainty, based on the output of the nine GCMs applied, reveals that expected water shortage ranges from 85 km3 yr-1 to 283 km3 yr-1~in 2050. The analysis shows that 22% of the water shortage can be attributed to climate change and 78% to changes in socio-economic factors.

  12. 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.

  13. Spatial and temporal patterns of methane dynamics in the tropical mangrove dominated estuary, NE coast of Bay of Bengal, India

    NASA Astrophysics Data System (ADS)

    Biswas, H.; Mukhopadhyay, S. K.; Sen, S.; Jana, T. K.

    2007-11-01

    Seasonal and spatial variation of dissolved and atmospheric methane (CH 4) was measured in the estuaries of the Sundarban mangrove ecosystem from January to December 2003. This unique mangrove forest ecosystem (9630 km 2), a part of the Hooghly-Matla estuarine system (NE coast of Bay of Bengal) comprises about 3% of the total area of the world's mangroves. Dissolved methane concentrations in the mangrove dominated estuarine water (Muriganga, Saptamukhi and Thakuran) were observed between 11.0 and 129.0 nmol L - 1 with emission rates between 1.97 and 134.6 μmol m - 2 d - 1 . Methane emission showed maximum rate during post-monsoon when phytoplankton reached blooming proportion. During post-monsoon materials transported from the mangrove forest could stimulate phytoplankton bloom when transparency of water column was increased and river input of nutrient was low. However, dissolved methane concentrations in the Hooghly estuary, the main river water flushing channel showed lower values between 10.3 and 59.25 nmol L - 1 with emission rates between 0.88 and 148.6 μmol m - 2 d - 1 . Methane concentrations in the salinity gradient zone of the Hooghly estuary did not show any decreasing trend with increased salinity due to its lateral transport from the mangrove forest situated at the lower stretch of the estuary. Dissolved methane concentration in the pore water collected from the virgin mangrove forest showed a maximum concentration of 5769 nmol L - 1 which was considerably lower compared to that of coastal salt marsh, tidal fresh water wetland. This indicated intense oxidation or out competition of methanogenic bacteria by sulfate and nitrate reducing bacteria. Methane emission from the adjacent forest ecosystem (18.36 mmol m - 2 d - 1 ) was higher compared to that in the mangrove water. Considering methane emission rates from the aquatic and forest ecosystems, an area average rate of 47.28 × 10 5 mol km - 2 yr - 1 for Sundarban mangrove environment was obtained

  14. ALMA Compact Array observations of the Fried Egg nebula: Evidence for large-scale asymmetric mass-loss from the yellow hypergiant IRAS 17163-3907.

    PubMed

    Wallström, S H J; Lagadec, E; Muller, S; Black, J H; Cox, N L J; Galván-Madrid, R; Justtanont, K; Longmore, S; Olofsson, H; Oudmaijer, R D; Quintana-Lacaci, G; Szczerba, R; Vlemmings, W; van Winckel, H; Zijlstra, A

    2017-01-10

    Yellow hypergiants are rare and represent a fast evolutionary stage of massive evolved stars. That evolutionary phase is characterised by a very intense mass loss, the understanding of which is still very limited. Here we report ALMA Compact Array observations of a 50″-mosaic toward the Fried Egg nebula, around one of the few Galactic yellow hypergiants IRAS 17163-3907. The emission from the (12)CO J=2-1 line, H30α recombination line, and continuum is imaged at a resolution of ~8″, revealing the morphology of the molecular environment around the star. The continuum emission is unresolved and peaks at the position of the star. The radio recombination line H30α shows unresolved emission at the star, with an approximately gaussian spectrum centered on a velocity of 21±3 km s(-1) with a width of 57±6 km s(-1). In contrast, the CO 2-1 emission is complex and decomposes into several components beyond the contamination from interstellar gas in the line of sight. The CO spectrum toward the star is a broad plateau, centered at the systemic velocity of +18 km s(-1) and with an expansion velocity of 100±10 km s(-1). Assuming isotropic and constant mass-loss, we estimate a mass-loss rate of 8±1.5 ×10(-5) M⊙ yr(-1). At a radius of 25″ from the star, we detect CO emission associated with the dust ring previously imaged by Herschel. The kinematics of this ring, however, is not consistent with an expanding shell, but show a velocity gradient of vsys ±20 km s(-1). In addition, we find a puzzling bright feature radially connecting the star to the CO ring, at a velocity of +40 km s(-1) relative to the star. This spur feature may trace a unidirectional ejection event from the star. Our ACA observations reveal the complex morphology around IRAS 17163 and illustrate the breakthroughs that ALMA will bring to the field of massive stellar evolution.

  15. SN 2007uy - metamorphosis of an aspheric Type Ib explosion

    NASA Astrophysics Data System (ADS)

    Roy, Rupak; Kumar, Brijesh; Maund, Justyn R.; Schady, Patricia; Olivares, E. Felipe; Malesani, Daniele; Leloudas, Giorgos; Nandi, Sumana; Tanvir, Nial; Milisavljevic, Dan; Hjorth, Jens; Misra, Kuntal; Kumar, Brajesh; Pandey, S. B.; Sagar, Ram; Chandola, H. C.

    2013-09-01

    The supernovae (SNe) of Type Ibc are rare and the detailed characteristics of these explosions have been studied only for a few events. Unlike Type II SNe, the progenitors of Type Ibc have never been detected in pre-explosion images. So, to understand the nature of their progenitors and the characteristics of the explosions, investigation of proximate events is necessary. Here we present the results of multiwavelength observations of Type Ib SN 2007uy in the nearby (˜29.5 Mpc) galaxy NGC 2770. Analysis of the photometric observations revealed this explosion as an energetic event with peak absolute R-band magnitude -18.5 ± 0.16, which is about 1 mag brighter than the mean value (-17.6 ± 0.6) derived for well observed Type Ibc events. The SN is highly extinguished, E(B - V) = 0.63 ± 0.15 mag, mainly due to foreground material present in the host galaxy. From optical light curve modelling we determine that about 0.3 M⊙ radioactive 56Ni is produced and roughly 4.4 M⊙ material is ejected during this explosion with liberated energy ˜15 × 1051 erg, indicating the event to be an energetic one. Through optical spectroscopy, we have noticed a clear aspheric evolution of several line-forming regions, but no dependency of asymmetry is seen on the distribution of 56Ni inside the ejecta. The SN shock interaction with the circumstellar material is clearly noticeable in radio follow-up, presenting a synchrotron self-absorption dominated light curve with a contribution of free-free absorption during the early phases. Assuming a Wolf-Rayet (WR) star, with wind velocity ≳ 103 km s- 1, as a progenitor, we derive a lower limit to the mass-loss rate inferred from the radio data as M˙ ⪆ 2.4 × 10-5 M⊙ yr-1, which is consistent with the results obtained for other Type Ibc SNe bright at radio frequencies.

  16. 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

  17. Submillimeter properties of Sagittarius A*: The polarization and spectrum from 230 to 690 GHz and the submillimeter array polarimeter

    NASA Astrophysics Data System (ADS)

    Marrone, Daniel Patrick

    Sagittarius A* is the supermassive black hole at the center of our galaxy; as the nearest example of a low-luminosity active galactic nucleus it provides an excellent opportunity to understand these objects. Submillimeter data are particularly important for examining this source because of the unique polarization and spectral features in this band. In this thesis I report several new observations of the polarization and spectrum of Sgr A* obtained with the Submillimeter Array (SMA). I present the first measurement of Faraday rotation in Sgr A*. The rotation measure is (-5.6 0.7) 10 5 rad m -2 , restricting the accretion rate to the range 2 10 -7 to 2 10 -9 [Special characters omitted.] yr -1 . These boundaries jointly increase if the magnetic field is sub-equipartition or disordered. The stability in the rotation measure limits accretion variability to 25%. I find large variations in the linear polarization on timescales of minutes to months, the first measurements of variability on intraday timescales. I report the observation of an interesting polarization variation that may lead to future measurements of the black hole spin. I am also able to identify variations in the intrinsic polarization direction of the source. These results demonstrate the utility of polarization for examining changes very close to the black hole. Finally, I show that the spectrum of Sgr A* peaks around 350 GHz, limiting the luminosity of the source to 200 [Special characters omitted.] , or 10 -9 L E . The majority of these results rely on observations obtained with the polarimeter I constructed for the SMA. I discuss the design and testing of the instrument and its expected performance. I review the principles of interferometric polarimetry, polarization calibration, and the origins of non-ideal response (or "leakage") in the polarimeter. Extensive calibration observations show that the leakages are extremely stable and exhibit the frequency behavior expected from theory. The precision of

  18. The relativistic pulsar-white dwarf binary PSR J1738+0333 - II. The most stringent test of scalar-tensor gravity

    NASA Astrophysics Data System (ADS)

    Freire, Paulo C. C.; Wex, Norbert; Esposito-Farèse, Gilles; Verbiest, Joris P. W.; Bailes, Matthew; Jacoby, Bryan A.; Kramer, Michael; Stairs, Ingrid H.; Antoniadis, John; Janssen, Gemma H.

    2012-07-01

    We report the results of a 10-year timing campaign on PSR J1738+0333, a 5.85-ms pulsar in a low-eccentricity 8.5-h orbit with a low-mass white dwarf companion. We obtained 17 376 pulse times of arrival with a stated uncertainty smaller than ?s and weighted residual rms of ?s. The large number and precision of these measurements allow highly significant estimates of the proper motion μα, δ= (+7.037 ± 0.005, +5.073 ± 0.012) mas yr-1, parallax πx = (0.68 ± 0.05) mas and a measurement of the apparent orbital decay, ? (all 1σ uncertainties). The measurements of μα, δ and πx allow for a precise subtraction of the kinematic contribution to the observed orbital decay; this results in a significant measurement of the intrinsic orbital decay: ?. This is consistent with the orbital decay from the emission of gravitational waves predicted by general relativity, ?, i.e. general relativity passes the test represented by the orbital decay of this system. This agreement introduces a tight upper limit on dipolar gravitational wave emission, a prediction of most alternative theories of gravity for asymmetric binary systems such as this. We use this limit to derive the most stringent constraints ever on a wide class of gravity theories, where gravity involves a scalar-field contribution. When considering general scalar-tensor theories of gravity, our new bounds are more stringent than the best current Solar system limits over most of the parameter space, and constrain the matter-scalar coupling constant ? to be below the 10-5 level. For the special case of the Jordan-Fierz-Brans-Dicke, we obtain the 1σ bound ?, which is within a factor of 2 of the Cassini limit. We also use our limit on dipolar gravitational wave emission to constrain a wide class of theories of gravity which are based on a generalization of Bekenstein's Tensor-Vector-Scalar gravity, a relativistic formulation of modified Newtonian dynamics.

  19. The wind speeds, dust content, and mass-loss rates of evolved AGB and RSG stars at varying metallicity

    NASA Astrophysics Data System (ADS)

    Goldman, Steven R.; van Loon, Jacco Th.; Zijlstra, Albert A.; Green, James A.; Wood, Peter R.; Nanni, Ambra; Imai, Hiroshi; Whitelock, Patricia A.; Matsuura, Mikako; Groenewegen, Martin A. T.; Gómez, José F.

    2017-02-01

    We present the results of our survey of 1612-MHz circumstellar OH maser emission from asymptotic giant branch (AGB) stars and red supergiants (RSGs) in the Large Magellanic Cloud (LMC). We have discovered four new circumstellar maser sources in the LMC, and increased the number of reliable wind speeds from infrared (IR) stars in the LMC from 5 to 13. Using our new wind speeds, as well as those from Galactic sources, we have derived an updated relation for dust-driven winds: vexp ∝ ZL0.4. We compare the subsolar metallicity LMC OH/IR stars with carefully selected samples of more metal-rich OH/IR stars, also at known distances, in the Galactic Centre and Galactic bulge. We derive pulsation periods for eight of the bulge stars for the first time by using near-IR photometry from the Vista Variables in the Via Lactea survey. We have modelled our LMC OH/IR stars and developed an empirical method of deriving gas-to-dust ratios and mass-loss rates by scaling the models to the results from maser profiles. We have done this also for samples in the Galactic Centre and bulge and derived a new mass-loss prescription which includes luminosity, pulsation period, and gas-to-dust ratio dot{M} = 1.06^{+3.5}_{-0.8} × }10^{-5 (L/10^4 L_{⊙})^{0.9± 0.1}(P/500 {d})^{0.75± 0.3} (r_gd/200)^{-0.03± 0.07} M⊙ yr-1. The tightest correlation is found between mass-loss rate and luminosity. We find that the gas-to-dust ratio has little effect on the mass-loss of oxygen-rich AGB stars and RSGs within the Galaxy and the LMC. This suggests that the mass-loss of oxygen-rich AGB stars and RSGs is (nearly) independent of metallicity between a half and twice solar.

  20. ALMA Compact Array observations of the Fried Egg nebula. Evidence for large-scale asymmetric mass-loss from the yellow hypergiant IRAS 17163-3907

    NASA Astrophysics Data System (ADS)

    Wallström, S. H. J.; Lagadec, E.; Muller, S.; Black, J. H.; Cox, N. L. J.; Galván-Madrid, R.; Justtanont, K.; Longmore, S.; Olofsson, H.; Oudmaijer, R. D.; Quintana-Lacaci, G.; Szczerba, R.; Vlemmings, W.; van Winckel, H.; Zijlstra, A.

    2017-01-01

    Yellow hypergiants are rare and represent a fast evolutionary stage of massive evolved stars. That evolutionary phase is characterised by a very intense mass loss, the understanding of which is still very limited. Here we report ALMA Compact Array observations of a 50''-mosaic toward the Fried Egg nebula, around one of the few Galactic yellow hypergiants IRAS 17163-3907. The emission from the 12CO J = 2-1 line, H30α recombination line, and continuum is imaged at a resolution of 8'', revealing the morphology of the molecular environment around the star. The continuum emission is unresolved and peaks at the position of the star. The radio recombination line H30α shows unresolved emission at the star, with an approximately Gaussian spectrum centered on a velocity of 21 ± 3km s-1 with a width of 57 ± 6km s-1. In contrast, the CO 2-1 emission is complex and decomposes into several components beyond the contamination from interstellar gas in the line of sight. The CO spectrum toward the star is a broad plateau, centered at the systemic velocity of +18 km s-1 and with an expansion velocity of 100 ± 10km s-1. Assuming isotropic and constant mass-loss, we estimate a mass-loss rate of 8 ± 1.5 × 10-5M⊙ yr-1. At a radius of 25'' from the star, we detect CO emission associated with the dust ring previously imaged by Herschel. The kinematics of this ring, however, is not consistent with an expanding shell, but show a velocity gradient of vsys ± 20km s-1. In addition, we find a puzzling bright feature radially connecting the star to the CO ring, at a velocity of +40 km s-1 relative to the star. This spur feature may trace a unidirectional ejection event from the star. Our ACA observations reveal the complex morphology around IRAS 17163 and illustrate the breakthroughs that ALMA will bring to the field of massive stellar evolution.

  1. 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].

  2. The Importance of Volcanoes as a Source of Mercury to the Atmosphere

    NASA Astrophysics Data System (ADS)

    Witt, M. L.; Pyle, D. M.; Mather, T. A.; Aiuppa, A.; Bagnato, E.

    2008-12-01

    Mercury is a toxic metal which has a long lifetime in the atmosphere, (~ 1 year). This long lifetime enables it to be carried vast distances and the metal is found in elevated concentrations in remote regions of the world. There is some debate at present regarding the quantity of mercury released by volcanoes and its relative significance to the natural Hg budget. In order to better understand the role of volcanoes in the global mercury budget we have carried out a number of field campaigns to evaluate the Hg/S ratios in volcanic gases around the world. Measurements have been made of emissions of Masaya (Nicaragua), Etna and Vulcano (Italy), Tatun (Taiwan), Taal and Makiling (Philippines) and Kilauea (Hawaii, USA). Emissions from open vents, fumaroles, hot springs, bubbling mud pools and altered ground were investigated at these sites. A Lumex 915+ portable mercury vapour spectrometer was employed to record real-time gaseous elemental mercury (GEM) concentrations alongside a Multi-GAS sensor box developed to monitor SO2, H2S, CO2, humidity, temperature and pressure. These measurements were carried out in parallel with the collection of total gaseous mercury (TGM) on gold coated sand traps, particulate Hg (Hg(p)) on quartz mini-traps, reactive gaseous Hg (RGM) on glass denuders and sulphur on filter packs. As observed in studies of background air Hg, most of the GEM was the dominant form in the volcanic gases. While RGM and Hg(p) represent only a few % of the Hg present, concentrations of these species in volcanic air were several orders of magnitude higher than observed in background and industrial air. GEM/S ratios were determined and used in conjunction with the SO2 volcanic flux to estimate Hg fluxes. GEM/S ratios in open vent emissions at Masaya and Etna were between 10-6 and 10-5, combined with their SO2 fluxes this gives Hg fluxes of 7.2 and 5.4 t yr-1 respectively. If representative of other volcanoes, these results suggest degassing of basaltic magma is an

  3. The Afterglow and Early-type Host Galaxy of the Short GRB 150101B at z = 0.1343

    NASA Astrophysics Data System (ADS)

    Fong, W.; Margutti, R.; Chornock, R.; Berger, E.; Shappee, B. J.; Levan, A. J.; Tanvir, N. R.; Smith, N.; Milne, P. A.; Laskar, T.; Fox, D. B.; Lunnan, R.; Blanchard, P. K.; Hjorth, J.; Wiersema, K.; van der Horst, A. J.; Zaritsky, D.

    2016-12-01

    We present the discovery of the X-ray and optical afterglows of the short-duration GRB 150101B, pinpointing the event to an early-type host galaxy at z = 0.1343 ± 0.0030. This makes GRB 150101B the most nearby short gamma-ray burst (GRB) with an early-type host galaxy discovered to date. Fitting the spectral energy distribution of the host galaxy results in an inferred stellar mass of ≈ 7× {10}10 {M}⊙ , stellar population age of ≈2-2.5 Gyr, and star formation rate of ≲0.4 M ⊙ yr-1. The host of GRB 150101B is one of the largest and most luminous short GRB host galaxies, with a B-band luminosity of ≈ 4.3{L}* and half-light radius of ≈8 kpc. GRB 150101B is located at a projected distance of 7.35 ± 0.07 kpc from its host center and lies on a faint region of its host rest-frame optical light. Its location, combined with the lack of associated supernova, is consistent with an NS-NS/NS-BH merger progenitor. From modeling the evolution of the broadband afterglow, we calculate isotropic-equivalent gamma-ray and kinetic energies of ≈ 1.3× {10}49 erg and ≈ (6{--}14)× {10}51 erg, respectively, a circumburst density of ≈ (0.8{--}4)× {10}-5 cm-3, and a jet opening angle of ≳9°. Using observations extending to ≈30 days, we place upper limits of ≲ (2{--}4)× {10}41 erg s-1 on associated kilonova emission. We compare searches following previous short GRBs to existing kilonova models and demonstrate the difficulty of performing effective kilonova searches from cosmological short GRBs using current ground-based facilities. We show that at the Advanced LIGO/VIRGO horizon distance of 200 Mpc, searches reaching depths of ≈23-24 AB mag are necessary to probe a meaningful range of kilonova models.

  4. Kepler’s Supernova: An Overluminous Type Ia Event Interacting with a Massive Circumstellar Medium at a Very Late Phase

    NASA Astrophysics Data System (ADS)

    Katsuda, Satoru; Mori, Koji; Maeda, Keiichi; Tanaka, Masaomi; Koyama, Katsuji; Tsunemi, Hiroshi; Nakajima, Hiroshi; Maeda, Yoshitomo; Ozaki, Masanobu; Petre, Robert

    2015-07-01

    We have analyzed XMM-Newton, Chandra, and Suzaku observations of three similarly aged, ejecta-dominated supernova remnants (SNRs), Kepler's SNR, Tycho's SNR, and SNR 0509-67.5, to investigate the properties of the SN ejecta and the circumstellar medium (CSM). By simply comparing the X-ray spectra, we find that line intensity ratios of iron-group elements (IGEs) to intermediate-mass elements (IMEs) for Kepler's SNR and SNR 0509-67.5 are much higher than those for Tycho's SNR. Given that Tycho's SNR and SNR 0509-67.5 are thought to be the remnants of a typical SN Ia and an overluminous SN Ia, respectively, we argue that Kepler is the product of an overlumious SN Ia. This inference is supported by our spectral modeling, which reveals the IGE and IME masses, respectively, to be {0.95}-0.37+0.34 {M}⊙ and {0.12}-0.05+0.19 {M}⊙ (Kepler's SNR), {0.75}-0.15+0.51 {M}⊙ and {0.34}-0.25+0.08 {M}⊙ (SNR 0509-67.5), and {0.35}-0.15+0.55 {M}⊙ and {0.70}-0.28+0.12 {M}⊙ (Tycho's SNR). We find that the CSM component in Kepler's SNR consists of tenuous diffuse gas (˜0.3 {M}⊙ ) present throughout the entire remnant, plus dense knots (˜0.035 {M}⊙ ). Since both of them show N overabundance, their origin would be CNO-processed material from the progenitor system. The mass of the diffuse CSM allows us to infer the pre-SN mass-loss rate to be ˜ 1.5× {10}-5(vw/10 km s-1) {M}⊙ yr-1. The dense knots have slow proper motions and relatively small ionization timescales; hence, they were likely located a few parsecs away from the progenitor at the explosion. We thus argue that Kepler's SN was an overluminous (91T-like) event that recently started to interact with the massive CSM. This supports the possible link between 91T-like SNe and “Ia-CSM” SNe.

  5. 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

  6. Millimeter- and Submillimeter-Wave Observations of the OMC-2/3 Region. I. Dispersing and Rotating Core around the Intermediate-Mass Protostar MMS 7

    NASA Astrophysics Data System (ADS)

    Takahashi, Satoko; Saito, Masao; Takakuwa, Shigehisa; Kawabe, Ryohei

    2006-11-01

    We report the results of H13CO+ (1-0), CO (1-0), and 3.3 mm dust continuum observations toward MMS 7, one of the strongest millimeter-wave sources in OMC-3, with the Nobeyama Millimeter Array (NMA) and the Nobeyama 45 m telescope. With the NMA, we detected centrally condensed 3.3 mm dust continuum emission, which coincides with the mid-infrared (MIR) source and the free-free jet. Our H13CO+ observations revealed a disklike envelope around MMS 7, whose size and mass are 0.15×0.11 pc and 5.1 Msolar, respectively. The outer portion of the disklike envelope has a fan-shaped structure, which delineates the rim of the observed CO outflow. The position-velocity diagrams in the H13CO+ (1-0) emission show that the velocity field in the disklike envelope is composed of a dispersing gas motion and a possible rigid-like rotation. The mass-dispersing rate is estimated to be 3.4×10-5 Msolar yr-1, which implies that MMS 7 has an ability to disperse ~10 Msolar during the protostellar evolutional time. The specific angular momentum in the disklike envelope is nearly 2 orders of magnitude larger than that in low-mass cores. The turnover point of the power law of the angular momentum distribution in the disklike envelope (<=0.007 pc), which is likely to be related to the outer radius of the central mass accretion, is similar in size to the 3.3 mm dust condensation. We propose that MMS 7 is in the last stage of the main accretion phase and that a substantial portion of the outer gas has already been dispersed, while mass accretion may still be ongoing at the innermost region, traced by the dusty condensation. Based on the observations made at the Nobeyama Radio Observatory, which is a branch of the National Astronomical Observatory, an interuniversity research institute operated by the Ministry of Education, Culture, Sports, Science, and Technology of Japan.

  7. 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

  8. Evolution of Young Stars and Their Disks in Serpens

    NASA Astrophysics Data System (ADS)

    Oliveira, Isa; Merín, Bruno; Pontoppidan, Klaus; van Dishoeck, Ewine

    2010-11-01

    Unbiased, flux-limited surveys of protoplanetary disks and their parent stars currently exist for only a few clouds, primarily Taurus and IC 348, selected primarily by optical and near-IR data. Such surveys are essential to address questions of disk evolution as a function of stellar parameters such as spectral type, age, accretion activity and environment. Using the ‘Cores to Disks’ (c2d) Spitzer Legacy Program, we discovered a new population of young stellar objects (YSOs) in a region of only 0.8 deg2 in the Serpens Molecular Cloud. This sample contains 150 mid-IR bright (≥ 3 mJy at 8 μm) YSOs with infrared excess, having a broad range of SED types and luminosities. Serpens is therefore a unique target region for obtaining a complete, well-defined sample of multi-wavelength observations of young stars in a possible evolutionary sequence. Compared with other clouds such as Taurus and Chamaeleon, Serpens has an exceptionally high star-formation rate (5.7 × 10-5 M⊙ yr-1). Follow-up complimentary observations in the optical, near- and mid-infrared (Spitzer/IRS GO3) have allowed us to characterize both the central stars and the surrounding disks. The shape and slope of the mid-infrared excess provide information on the flaring geometry of the disks. The spectral features give constraints on grain growth and mineralogy, which in turn probes heating and radial mixing. The presence of PAH features traces UV radiation, whereas Hα and Brγ are used as diagnostics of accretion. Assuming that all stars within a sufficiently small region are nearly coeval, this provides direct constraints on the importance of environment and initial conditions on disk evolution. In this meeting, we have presented our latest results on this rich populations of YSOs, as detailed in Oliveira et al. (2009, 2010). We have discussed connections between the evolution of the disks and that of their harboring stars, and the processes that determine the evolutionary sequence of

  9. 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

  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. 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

  12. 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.

  13. 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.

  14. 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.

  15. Heavy metal deposition and cycling at two Mediterranean holm oak (Quercus ilex L.) forests in northeastern Spain

    NASA Astrophysics Data System (ADS)

    Avila, A.; Alarcon, M.; Rodrigo, A.

    2003-05-01

    Trace metal deposition in precipitation was not significantly different in two holm oak forests with contrasted exposure to pollution in the area around Barcelona (Northeastern Spain), but dry deposition was higher at the more exposed site. Rain events of European origin had higher concentrations of Cu, Pb, Zn and Cd than those from African, Atlantic Ocean and Local provenances. Estimated from the recovered quantities in artificial plates, dry deposition was, for Zn, Cu and Pb: 342, 25 and 20 g ha^{-1} yr^{-1}, respectively at the exposed site, and 254, 13 and 15 g ha^{-1} yr^{-1} at the sheltered one. Deposition in bulk precipitation was lower than dry deposition: 221, 6.2 and 6.4 g ha^{-1} yr^{-1} for Zn. Cu and Pb, respectively (average of the two sites).

  16. A geophysical interpretation of the secular displacement and gravity rates observed at Ny-Ålesund, Svalbard in the Arctic-effects of post-glacial rebound and present-day ice melting

    NASA Astrophysics Data System (ADS)

    Sato, Tadahiro; Okuno, Jun'ichi; Hinderer, Jacques; MacMillan, Daniel S.; Plag, Hans-Peter; Francis, Olivier; Falk, Reinhard; Fukuda, Yoichi

    2006-06-01

    We have analysed the Ny-Ålesund very long baseline interferometry (VLBI) data over the period 1994 August to 2004 May, and we obtain secular displacement rates relative to a NNR-NUVEL-1A reference frame of 0.2 +/- 0.5 mm yr-1, -1.7 +/- 0.5 mm yr-1 and 4.8 +/- 1.1 mm yr-1 for the north, east and vertical directions, respectively. The corresponding global positioning system (GPS) station displacement rates relative to the same reference frame for the north, east, and vertical directions are 0.2 +/- 0.6 mm yr-1, -2.3 +/- 0.6 mm yr-1, and 6.4 +/- 1.5 mm yr-1 at NYA1 and -0.1 +/- 0.5 mm yr-1, -1.6 +/- 0.5 mm yr-1, and 6.9 +/- 0.9 mm yr-1 at NALL, where these GPS rates were derived from the ITRF2000 velocity solution of Heflin. From the comparison at 25 globally distributed collocated sites, we found that the difference in uplift rate between VLBI and GPS at Ny-Ålesund is mainly due to a GPS reference frame scale rate error corresponding to 1.6 mm yr-1 in the GPS vertical rates. The uplift rate was estimated to be 5.2 +/- 0.3 mm yr-1 from the analysis of the tide gauge data at Ny-Ålesund. Hence the uplift rates obtained from three different kinds of data are very consistent each other. The absolute gravity (AG) measurements at Ny-Ålesund, which were carried out four times (period: 1998-2002) by three different FG5 absolute gravimeters, lead to a decreasing secular rate of -2.5 +/- 0.9μGal yr-1 (1 μGal = 10-8 m s-2). In this analysis, the actual data obtained from a superconducting gravimeter at Ny-Ålesund were used in the corrections for the gravity tide (including the ocean tide effect) and for the air pressure effect. We have estimated three geophysical contributions to examine the observed rates: (1) the effect of the sea-level (SL) change on a timescale of a few decades, (2) the effect of the present-day ice melting (PDIM) in Svalbard and (3) the sensitivity of the computed post-glacial rebound (PGR) effects to different choices of the models of past ice

  17. 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.

  18. Urban recharge beneath low impact development and effects of climate variability and change

    NASA Astrophysics Data System (ADS)

    Newcomer, Michelle E.; Gurdak, Jason J.; Sklar, Leonard S.; Nanus, Leora

    2014-02-01

    low impact development (LID) planning and best management practices (BMPs) effects on recharge is important because of the increasing use of LID BMPs to reduce storm water runoff and improve surface-water quality. LID BMPs are microscale, decentralized management techniques such as vegetated systems, pervious pavement, and infiltration trenches to capture, reduce, filter, and slow storm water runoff. Some BMPs may enhance recharge, which has often been considered a secondary management benefit. Here we report results of a field and HYDRUS-2D modeling study in San Francisco, California, USA to quantify urban recharge rates, volumes, and efficiency beneath a LID BMP infiltration trench and irrigated lawn considering historical El Niño/Southern Oscillation (ENSO) variability and future climate change using simulated precipitation from the Geophysical Fluid Dynamic Laboratory (GFDL) A1F1 climate scenario. We find that in situ and modeling methods are complementary, particularly for simulating historical and future recharge scenarios, and the in situ data are critical for accurately estimating recharge under current conditions. Observed (2011-2012) and future (2099-2100) recharge rates beneath the infiltration trench (1750-3710 mm yr-1) were an order of magnitude greater than beneath the irrigated lawn (130-730 mm yr-1). Beneath the infiltration trench, recharge rates ranged from 1390 to 5840 mm yr-1 and averaged 3410 mm yr-1 for El Niño years (1954-2012) and from 1540 to 3330 mm yr-1 and averaged 2430 mm yr-1 for La Niña years. We demonstrate a clear benefit for recharge and local groundwater resources using LID BMPs.

  19. Atmospheric histories and global emissions of halons H-1211 (CBrClF2), H-1301 (CBrF3), and H-2402 (CBrF2CBrF2)

    NASA Astrophysics Data System (ADS)

    Vollmer, Martin K.; Mühle, Jens; Trudinger, Cathy M.; Rigby, Matthew; Montzka, Stephen A.; Harth, Christina M.; Miller, Benjamin R.; Henne, Stephan; Krummel, Paul B.; Hall, Bradley D.; Young, Dickon; Kim, Jooil; Arduini, Jgor; Wenger, Angelina; Yao, Bo; Reimann, Stefan; O'Doherty, Simon; Maione, Michela; Etheridge, David M.; Li, Shanlan; Verdonik, Daniel P.; Park, Sunyoung; Dutton, Geoff; Steele, L. Paul; Lunder, Chris R.; Rhee, Tae Siek; Hermansen, Ove; Schmidbauer, Norbert; Wang, Ray H. J.; Hill, Matthias; Salameh, Peter K.; Langenfelds, Ray L.; Zhou, Lingxi; Blunier, Thomas; Schwander, Jakob; Elkins, James W.; Butler, James H.; Simmonds, Peter G.; Weiss, Ray F.; Prinn, Ronald G.; Fraser, Paul J.

    2016-04-01

    We report ground-based atmospheric measurements and emission estimates for the halons H-1211 (CBrClF2), H-1301 (CBrF3), and H-2402 (CBrF2CBrF2) from the AGAGE (Advanced Global Atmospheric Gases Experiment) and the National Oceanic and Atmospheric Administration global networks. We also include results from archived air samples in canisters and from polar firn in both hemispheres, thereby deriving an atmospheric record of nearly nine decades (1930s to present). All three halons were absent from the atmosphere until ˜1970, when their atmospheric burdens started to increase rapidly. In recent years H-1211 and H-2402 mole fractions have been declining, but H-1301 has continued to grow. High-frequency observations show continuing emissions of H-1211 and H-1301 near most AGAGE sites. For H-2402 the only emissions detected were derived from the region surrounding the Sea of Japan/East Sea. Based on our observations, we derive global emissions using two different inversion approaches. Emissions for H-1211 declined from a peak of 11 kt yr-1 (late 1990s) to 3.9 kt yr-1 at the end of our record (mean of 2013-2015), for H-1301 from 5.4 kt yr-1 (late 1980s) to 1.6 kt yr-1, and for H-2402 from 1.8 kt yr-1 (late 1980s) to 0.38 kt yr-1. Yearly summed halon emissions have decreased substantially; nevertheless, since 2000 they have accounted for ˜30% of the emissions of all major anthropogenic ozone depletion substances, when weighted by ozone depletion potentials.

  20. Structure and breakup history of the rifted margin of West Antarctica in relation to Cretaceous separation from Zealandia and Bellingshausen plate motion

    NASA Astrophysics Data System (ADS)

    Wobbe, F.; Gohl, K.; Chambord, A.; Sutherland, R.

    2012-04-01

    Geophysical data acquired using R/V Polarstern constrain the structure and age of the rifted oceanic margin of West Antarctica. West of the Antipodes Fracture Zone, the 145 km wide continent-ocean transition zone (COTZ) of the Marie Byrd Land sector resembles a typical magma-poor margin. New gravity and seismic reflection data indicates initial continental crust of thickness 24 km, that was stretched 90 km. Farther east, the Bellingshausen sector is broad and complex with abundant evidence for volcanism, the COTZ is ˜670 km wide, and the nature of crust within the COTZ is uncertain. Margin extension is estimated to be 106-304 km in this sector. Seafloor magnetic anomalies adjacent to Marie Byrd Land near the Pahemo Fracture Zone indicate full-spreading rate during c33-c31 (80-68 Myr) of 60 mm yr-1, increasing to 74 mm yr-1 at c27 (62 Myr), and then dropping to 22 mm yr-1 by c22 (50 Myr). Spreading rates were lower to the west. Extrapolation towards the continental margin indicates initial oceanic crust formation at around c34y (84 Myr). Subsequent motion of the Bellingshausen plate relative to Antarctica (84-62 Myr) took place east of the Antipodes Fracture Zone at rates <40 mm yr-1, typically 5-20 mm yr-1. The high extension rate of 30-60 mm yr-1 during initial margin formation is consistent with steep and symmetrical margin morphology, but subsequent motion of the Bellingshausen plate was slow and complex, and modified rift morphology through migrating deformation and volcanic centers to create a broad and complex COTZ.

  1. 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).

  2. A quantitative assessment of methane cycling in Hikurangi Margin sediments (New Zealand) using geophysical imaging and biogeochemical modeling

    NASA Astrophysics Data System (ADS)

    Luo, Min; Dale, Andrew W.; Haffert, Laura; Haeckel, Matthias; Koch, Stephanie; Crutchley, Gareth; De Stigter, Henko; Chen, Duofu; Greinert, Jens

    2016-12-01

    Takahe seep, located on the Opouawe Bank, Hikurangi Margin, is characterized by a well-defined subsurface seismic chimney structure ˜80,500 m2 in area. Subseafloor geophysical data based on acoustic anomaly layers indicated the presence of gas hydrate and free gas layers within the chimney structure. Reaction-transport modeling was applied to porewater data from 11 gravity cores to constrain methane turnover rates and benthic methane fluxes in the upper 10 m. Model results show that methane dynamics were highly variable due to transport and dissolution of ascending gas. The dissolution of gas (up to 3761 mmol m-2 yr-1) dwarfed the rate of methanogenesis within the simulated sediment column (2.6 mmol m-2 yr-1). Dissolved methane is mainly consumed by anaerobic oxidation of methane (AOM) at the base of the sulfate reduction zone and trapped by methane hydrate formation below it, with maximum rates in the central part of the chimney (946 and 2420 mmol m-2 yr-1, respectively). A seep-wide methane budget was constrained by combining the biogeochemical model results with geophysical data and led to estimates of AOM rates, gas hydrate formation, and benthic dissolved methane fluxes of 3.68 × 104 mol yr-1, 73.85 × 104 mol yr-1, and 1.19 × 104 mol yr-1, respectively. A much larger flux of methane probably escapes in gaseous form through focused bubble vents. The approach of linking geochemical model results with spatial geophysical data put forward here can be applied elsewhere to improve benthic methane turnover rates from limited single spot measurements to larger spatial scales.

  3. Modeling Potential Distribution and Carbon Dynamics of Natural Terrestrial Ecosystems: A Case Study of Turkey

    PubMed Central

    Evrendilek, Fatih; Berberoglu, Suha; Gulbeyaz, Onder; Ertekin, Can

    2007-01-01

    We derived a simple model that relates the classification of biogeoclimate zones, (co)existence and fractional coverage of plant functional types (PFTs), and patterns of ecosystem carbon (C) stocks to long-term average values of biogeoclimatic indices in a time- and space-varying fashion from climate–vegetation equilibrium models. Proposed Dynamic Ecosystem Classification and Productivity (DECP) model is based on the spatial interpolation of annual biogeoclimatic variables through multiple linear regression (MLR) models and inverse distance weighting (IDW) and was applied to the entire Turkey of 780,595 km2 on a 500 m × 500 m grid resolution. Estimated total net primary production (TNPP) values of mutually exclusive PFTs ranged from 108 ± 26 to 891 ± 207 Tg C yr-1 under the optimal conditions and from 16 ± 7 to 58 ± 23 Tg C yr-1 under the growth-limiting conditions for all the natural ecosystems in Turkey. Total NPP values of coexisting PFTs ranged from 178 ± 36 to 1231 ± 253 Tg C yr-1 under the optimal conditions and from 23 ± 8 to 92 ± 31 Tg C yr-1 under the growth-limiting conditions. The national steady state soil organic carbon (SOC) storage in the surface one meter of soil was estimated to range from 7.5 ± 1.8 to 36.7 ± 7.8 Pg C yr-1 under the optimal conditions and from 1.3 ± 0.7 to 5.8 ± 2.6 Pg C yr-1 under the limiting conditions, with the national range of 1.3 to 36.7 Pg C elucidating 0.1% and 2.8% of the global SOC value (1272.4 Pg C), respectively. Our comparisons with literature compilations indicate that estimated patterns of biogeoclimate zones, PFTs, TNPP and SOC storage by the DECP model agree reasonably well with measurements from field and remotely sensed data.

  4. Comparison of acidic deposition to semi-natural ecosystems in Denmark—Coastal heath, inland heath and oak wood

    NASA Astrophysics Data System (ADS)

    Hansen, Birgitte; Nielsen, Knud Erik

    Acidic deposition to coastal heath, inland heath and oak wood in Denmark was determined from analysis of bulk precipitation and throughfall measurements for up to 3 yrs. The analysis aimed to determine the total annual sulphur and nitrogen deposition to the three different ecosystems. Total nitrogen deposition is especially difficult to assess due to uptake of nitrogen by the canopy, and difficulties in determining the dry deposition of each nitrogen species. An NH x-uptake estimation model is presented which assumes co-deposition of NH x+H + and SO x+NO y and exchange of NH x+H + for the leached Mg 2+, Ca 2+ and K + in the canopy. This approach makes it possible to estimate the dry deposition of reduced nitrogen (NH x). Dry deposited oxidized nitrogen (NO y) still remains unquantified with the throughfall method, and therefore this term is estimated from a generalized micro-meteorological model. Total annual nitrogen deposition was 29.0 kg ha -1 yr -1 for the oak wood, 18.3 kg ha -1 yr -1 for the inland heathland and 13.5 kg ha -1 yr -1 for the coastal heathland. The total annual acidic deposition (the sum of H +, SO x, NO y and NH x) was 3202 mol c ha -1 for the oak wood, 2228 mol c ha -1 for the inland heathland, and 2060 mol c ha -1 for the coastal heathland. However, this acid load has different effects on the ecosystems depending on the actual bio-geochemical reactions. The potential maximum acidification estimated for the oak wood (5512 mol c ha -1 yr -1) was almost twice as high as for the inland heathland (3815 mol c H + ha -1 yr -1) and for the coastal heathland (3383 mol cH + ha -1 yr -1).

  5. 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.

  6. 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.

  7. Carbon Budget of an Alluvial Floodplain in Northwest Montana, USA

    NASA Astrophysics Data System (ADS)

    Appling, A.; Poole, G.; Bernhardt, E. S.; Kimball, J. S.; Stanford, J.

    2009-12-01

    Alluvial floodplains can be substantial sources of carbon dioxide and sinks for particulate carbon, making them important players in the global aquatic carbon cycle. However, carbon budgets for large floodplains are poorly constrained, especially for floodplains with large hyporheic aquifers and high connectivity to the river channel. We synthesized the results of seven recent studies to construct a carbon budget for the Nyack Floodplain on the Middle Fork Flathead River in northwest Montana. For the whole floodplain, including river channel, hyporheic aquifer, and riparian soils and vegetation, estimated carbon losses exceed inputs by 9.1 gC m-3 yr-1. The imbalance is primarily driven by microbial and invertebrate respiration in the aquifer (8.4 and 0.3 gC m-3 yr-1, respectively). Despite the fact that these respiration rates are among the lowest reported in the literature, they dwarf other carbon inputs to the floodplain: riparian NPP is 1.8 gC m-3 yr-1; in-channel NPP is less than 0.001 gC m-3 yr-1, and riverine DOC inputs (4.8 gC m-3 yr-1) are exceeded by riverine DOC losses (5.9 gC m-3 yr-1). To begin resolving the apparent carbon imbalance, we establish a reasonable range for each flux in the carbon budget and identify key uncertainties. Our results point to the need for more research in three areas: First, we can constrain the aquifer carbon cycle by quantifying riparian soil leaching, root exudate production, and plant biomass turnover. Second, we should better understand upstream inputs of organic matter, both annually and during large episodic floods. Finally, we need to explore the interacting roles of hydrologic flowpaths, sediment texture, and buried organic matter in creating patchy habitats for microbes and invertebrates in the aquifer.

  8. Spatial and seasonal fluxes of the greenhouse gases N2O, CO2 and CH4 in a UK macrotidal estuary

    NASA Astrophysics Data System (ADS)

    Harley, J. F.; Carvalho, L.; Dudley, B.; Heal, K. V.; Rees, R. M.; Skiba, U.

    2015-02-01

    The spatial and seasonal dynamics of surface water fluxes of the greenhouse gases (GHG) CO2, CH4, and N2O were quantified in the Tay estuary, Scotland, on seven sampling occasions every 3 months during 2009/2010. This estuary is a relatively pristine river-dominated macrotidal estuary system of a type that is sparsely represented in global GHG flux studies. Significant spatial and temporal variability in GHG fluxes were measured, with similar spatial dynamics to that of other European estuaries. Greatest temporal and spatial variability in gas saturations were found for CH4, which was higher in the summer, with peaks in saturation occurring in the freshwater upper estuary and sharply decreasing in the mid-estuary mixing zone. Concentrations of CO2 and N2O were also generally higher in the upper to middle estuary in summer, although seasonality was less pronounced. Estimated air-sea fluxes also displayed significant spatial and temporal variability. Total annual CO2 emissions were greatest in the middle estuary zone (13.8 × 106 kg C yr-1), and lowest in the upper estuary (1.52 × 106 kg C yr-1). Seasonally, the highest CO2 emissions integrated across the estuary were in spring and autumn, with the lowest in winter. Total annual CH4 emissions were also highest in the middle estuary (0.05 × 106 kg C yr-1) and lowest in the upper estuary (0.01 × 106 kg C yr-1), whereas total N2O emissions, whilst highest in the middle estuary (2344 kg N yr-1), were lowest in the outer estuary (-435 kg N yr-1). Emissions of CH4 and N2O were substantially higher in the summer than any other season and lowest emissions were found in winter. The estimated annual exchange of both CO2 and N2O is substantially lower than those reported in other European macrotidal estuaries.

  9. Patterns of short-term sedimentation in a freshwater created marsh.

    PubMed

    Harter, Sarah K; Mitsch, William J

    2003-01-01

    This study investigated different sedimentation measurement techniques and examined patterns of short-term sedimentation in two 1-ha replicate created freshwater marshes in central Ohio, USA. Short-term (one-year) sediment accumulation above feldspar, clay, glitter, and sand artificial marker horizons was compared at different water depths and distances from wetland inflow. A sediment budget was also constructed from turbidity and suspended sediment data for comparison with marker horizons. Glitter and sand marker horizons were the most successful for measuring sediment accumulation (81-100% marker recovery), while clay markers were completely unsuccessful. The sedimentation rate for both wetlands averaged 4.9 cm yr(-1) (36 kg m(-2) yr(-1)), and ranged from 1.82 to 9.23 cm yr(-1) (12.4 to 69.7 kg m(-2) yr(-1)). Sedimentation rates in deep, open water areas were significantly higher than in shallow, vegetated areas for both wetlands (t test, p < 0.05). However, observed sedimentation patterns may be attributed more to preferential flow through open water areas than to water depth or presence of vegetation. Contrary to the expected spatial distribution, sedimentation was highly variable within the wetlands, suggesting that bioturbation and turbulence may cause significant resuspension or that high hydrologic loads may distribute sediments throughout the basins. A sediment budget estimated sediment retention of approximately 740 g m(-2) yr(-1) per wetland (43% removal rate), yet gross sediment accumulation was 36,000 g m(-2) yr(-1) measured by marker horizons. These results suggest that erosive forces may have influenced sedimentation, but also may indicate problems with the sediment budget calculation methodology.

  10. Variability of projected terrestrial biosphere responses to elevated levels of atmospheric CO2 due to uncertainty in biological nitrogen fixation

    NASA Astrophysics Data System (ADS)

    Meyerholt, J.; Zaehle, S.; Smith, M. J.

    2015-12-01

    Including a terrestrial nitrogen (N) cycle in Earth system models has led to substantial attenuation of predicted biosphere-climate feedbacks. However, the magnitude of this attenuation remains uncertain. A particularly important, but highly uncertain process is biological nitrogen fixation (BNF), which is the largest natural input of N to land ecosystems globally. In order to quantify this uncertainty, and estimate likely effects on terrestrial biosphere dynamics, we applied six alternative formulations of BNF spanning the range of process formulations in current state-of-the-art biosphere models within a common framework, the O-CN model: a global map of static BNF rates, two empirical relationships between BNF and other ecosystem variables (net primary productivity (NPP) and evapotranspiration), two process-oriented formulations based on plant N status, and an optimality-based approach. We examined the resulting differences in model predictions under ambient and elevated atmospheric [CO2] and found that the predicted global BNF rates and their spatial distribution for contemporary conditions were broadly comparable, ranging from 95 to 134 Tg N yr-1 (median 119 Tg N yr-1), despite distinct regional patterns associated with the assumptions of each approach. Notwithstanding, model responses in BNF rates to elevated levels of atmospheric [CO2] (+200 ppm) ranged between -4 Tg N yr-1 (-3 %) and 56 Tg N yr-1 (+42 %) (median 7 Tg N yr-1 (+8 %)). As a consequence, future projections of global ecosystem carbon storage (+281 to +353 Pg C, or +13 to +16 %), as well as N2O emission (-1.6 to +0.5 Tg N yr-1, or -19 to +7 %) differed significantly across the different model formulations. Our results emphasize the importance of better understanding the nature and magnitude of BNF responses to change-induced perturbations, particularly through new empirical perturbation experiments and improved model representation.

  11. Variability of projected terrestrial biosphere responses to elevated levels of atmospheric CO2 due to uncertainty in biological nitrogen fixation

    NASA Astrophysics Data System (ADS)

    Meyerholt, Johannes; Zaehle, Sönke; Smith, Matthew J.

    2016-03-01

    Including a terrestrial nitrogen (N) cycle in Earth system models has led to substantial attenuation of predicted biosphere-climate feedbacks. However, the magnitude of this attenuation remains uncertain. A particularly important but highly uncertain process is biological nitrogen fixation (BNF), which is the largest natural input of N to land ecosystems globally. In order to quantify this uncertainty and estimate likely effects on terrestrial biosphere dynamics, we applied six alternative formulations of BNF spanning the range of process formulations in current state-of-the-art biosphere models within a common framework, the O-CN model: a global map of static BNF rates, two empirical relationships between BNF and other ecosystem variables (net primary productivity and evapotranspiration), two process-oriented formulations based on plant N status, and an optimality-based approach. We examined the resulting differences in model predictions under ambient and elevated atmospheric [CO2] and found that the predicted global BNF rates and their spatial distribution for contemporary conditions were broadly comparable, ranging from 108 to 148 Tg N yr-1 (median: 128 Tg N yr-1), despite distinct regional patterns associated with the assumptions of each approach. Notwithstanding, model responses in BNF rates to elevated levels of atmospheric [CO2] (+200 ppm) ranged between -4 Tg N yr-1 (-3 %) and 56 Tg N yr-1 (+42 %) (median: 7 Tg N yr-1 (+8 %)). As a consequence, future projections of global ecosystem carbon (C) storage (+281 to +353 Pg C, or +13 to +16 %) as well as N2O emission (-1.6 to +0.5 Tg N yr-1, or -19 to +7 %) differed significantly across the different model formulations. Our results emphasize the importance of better understanding the nature and magnitude of BNF responses to change-induced perturbations, particularly through new empirical perturbation experiments and improved model representation.

  12. Submarine groundwater discharge and associated nutrient fluxes into the Southern Yellow Sea: A case study for semi-enclosed and oligotrophic seas-implication for green tide bloom

    NASA Astrophysics Data System (ADS)

    Liu, Jian'an; Su, Ni; Wang, Xilong; Du, Jinzhou

    2017-01-01

    The biogenic elements concentrations in a coastal bay/estuary are strongly influenced not only by riverine input but also by submarine groundwater discharge (SGD) which has been identified as a typical process of land/ocean interactions in coastal zones. To assess the role of SGD in nutrient fluxes in the Southern Yellow Sea (SYS), 228Ra activities were measured in seawater collected in May 2014. Analyzing the sources and sinks of 228Ra, the flux of excess 228Ra through SGD was estimated to be (2.2 ± 1.0) ×1015 dpm yr-1. Based on the 228Ra mass balance model, we estimated the average SGD flux to be approximately (1.3 ± 0.87) ×1012 m3 yr-1 over the entire SYS, which is at least 3.3 times the estimated annual delivery from the Changjiang River into the SYS (˜1.3 × 1011 m3 yr-1). The SGD-derived biogenic elements loads (dissolved inorganic nitrogen (DIN), phosphorus (DIP) and silicon (DSi)) were estimated as (487 ± 384) × 109 mol yr-1, (2.8 ± 2.2) × 109 mol yr-1, and (313 ± 259) × 109 mol yr-1, respectively, which are approximately 18 times, 7 times and 13 times the riverine input from both mainland China and Korea. The accumulation nutrient fluxes derived by SGD may play one of the most important roles in the green tide bloom that originated from the Subei Shoal zone in the SYS. Additionally, DIN and DIP via SGD can provide the necessary amounts of nutrient for recovering nutrient concentrations to normal levels after the green tide bloom is terminated.

  13. South Atlantic interbasin exchanges of mass, heat, salt and anthropogenic carbon

    NASA Astrophysics Data System (ADS)

    Evans, G. R.; McDonagh, E. L.; King, B. A.; Bryden, H. L.; Bakker, D. C. E.; Brown, P. J.; Schuster, U.; Speer, K. G.; van Heuven, S. M. A. C.

    2017-02-01

    The exchange of mass, heat, salt and anthropogenic carbon (Cant) between the South Atlantic, south of 24°S, and adjacent ocean basins is estimated from hydrographic data obtained during 2008-2009 using an inverse method. Transports of anthropogenic carbon are calculated across the western (Drake Passage), eastern (30°E) and northern (24°S) boundaries. The freshwater overturning transport of 0.09 Sv is southward, consistent with an overturning circulation that exports freshwater from the North Atlantic, and consistent with a bistable Meridional Overturning Circulation (MOC), under conditions of excess freshwater perturbation. At 30°E, net eastward Antarctic Circumpolar Current (ACC) transport, south of the Subtropical Front, is compensated by a 15.9 ± 2.3 Sv westward flow along the Antarctic boundary. The region as a whole is a substantial sink for atmospheric anthropogenic carbon of 0.51 ± 0.37 Pg C yr-1, of which 0.18 ± 0.12 Pg C yr-1 accumulates and is stored within the water column. At 24°S, a 20.2 Sv meridional overturning is associated with a 0.11 Pg C yr-1 Cant overturning. The remainder is transported into the Atlantic Ocean north of 24°S (0.28 ± 0.16 Pg C yr-1) and Indian sector of Southern Ocean (1.12 ± 0.43 Pg C yr-1), having been enhanced by inflow through Drake Passage (1.07 ± 0.44 Pg C yr-1). This underlines the importance of the South Atlantic as a crucial element of the anthropogenic carbon sink in the global oceans.

  14. Area change of glaciers in the Canadian Rocky Mountains, 1919 to 2006

    NASA Astrophysics Data System (ADS)

    Tennant, C.; Menounos, B.; Wheate, R.; Clague, J. J.

    2012-12-01

    Glaciers in the Canadian Rocky Mountains constitute an important freshwater resource. To enhance our understanding of the influence climate and local topography have on glacier area, large numbers of glaciers of different sizes and attributes need to be monitored over periods of many decades. We used Interprovincial Boundary Commission Survey (IBCS) maps of the Alberta-British Columbia (BC) border (1903-1924), BC Terrain Resource Information Management (TRIM) data (1982-1987), and Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) imagery (2000-2002 and 2006) to document planimetric changes in glacier cover in the central and southern Canadian Rocky Mountains between 1919 and 2006. Over this period, glacier cover in the study area decreased by 590 ± 70 km2 (40 ± 5%), 17 of 523 glaciers disappeared and 124 glaciers fragmented into multiple ice masses. Glaciers smaller than 1.0 km2 experienced the greatest relative area loss (64 ± 8%), and relative area loss is more variable with small glaciers, suggesting that the local topographic setting controls the response of these glaciers to climate change. Small glaciers with low slopes, low mean/median elevations, south to west aspects, and high insolation experienced the largest reduction in area. Similar rates of area change characterize the periods 1919-1985 and 1985-2001; -6.3 ± 0.6 km2 yr-1 (-0.4 ± 0.1% yr-1) and -5.0 ± 0.5 km2 yr-1 (-0.5 ± 0.1% yr-1), respectively. The rate of area loss, however, increased over the period 2001-2006; -19.3 ± 2.4 km2 yr-1 (-2.0 ± 0.2% yr-1). Applying size class-specific scaling factors, we estimate a total reduction in glacier cover in the central and southern Canadian Rocky Mountains for the period 1919-2006 of 750 km2 (30%).

  15. 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)).

  16. Benthic nutrient fluxes in the Eastern Gotland Basin (Baltic Sea) with particular focus on microbial mat ecosystems

    NASA Astrophysics Data System (ADS)

    Noffke, A.; Sommer, S.; Dale, A. W.; Hall, P. O. J.; Pfannkuche, O.

    2016-06-01

    Benthic fluxes and water column distributions of dissolved inorganic nitrogen (DIN) and total dissolved phosphate (PO43 -) were measured in situ at 7 sites across a redox gradient from oxic to anoxic bottom waters in the Eastern Gotland Basin (Baltic Sea). The study area was divided into the oxic zone (60 to ca. 80 m water depth, O2 > 30 μM), the hypoxic transition zone (HTZ, ca. 80 to 120 m, O2 < 30 μM) and the deep anoxic and sulfidic basin (> ca. 120 m). Sediments in the HTZ were covered by mats of vacuolated sulfur bacteria. Ammonium (NH4+) fluxes in the deep basin and the HTZ were elevated at 0.6 mmol m- 2 d- 1 and 1 mmol m- 2 d- 1, respectively. Nitrate (NO3-) fluxes were directed into the sediment at all stations in the HTZ and were zero in the deep basin. PO43 - release was highest in the HTZ at 0.23 mmol m- 2 d- 1, with a further release of 0.2 mmol m- 2 d- 1 in the deep basin. Up-scaling the benthic fluxes to the Baltic Proper equals 109 kt yr- 1 of PO43 - and 266 kt yr- 1 of DIN. This is eight- and two-fold higher than the total external load of P (14 kt yr- 1) and DIN (140 kt yr- 1) in 2006 (HELCOM 2009b). The HTZ makes an important contribution to the internal nutrient loading in the Baltic Proper, releasing 70% of P (76 kt yr- 1) and 75% of DIN (200 kt yr- 1) despite covering only 51% of area.

  17. Historical deposition of mercury and selected trace elements to high-elevation National Parks in the Western U.S. inferred from lake-sediment cores

    NASA Astrophysics Data System (ADS)

    Mast, M. Alisa; Manthorne, David J.; Roth, David A.

    2010-07-01

    Atmospheric deposition of Hg and selected trace elements was reconstructed over the past 150 years using sediment cores collected from nine remote, high-elevation lakes in Rocky Mountain National Park in Colorado and Glacier National Park in Montana. Cores were age dated by 210Pb, and sedimentation rates were determined using the constant rate of supply model. Hg concentrations in most of the cores began to increase around 1900, reaching a peak sometime after 1980. Other trace elements, particularly Pb and Cd, showed similar post-industrial increases in lake sediments, confirming that anthropogenic contaminants are reaching remote areas of the Rocky Mountains via atmospheric transport and deposition. Preindustrial (pre-1875) Hg fluxes in the sediment ranged from 5.7 to 42 μg m -2 yr -1 and modern (post-1985) fluxes ranged from 17.7 to 141 μg m -2 yr -1. The average ratio of modern to preindustrial fluxes was 3.2, which is similar to remote lakes elsewhere in North America. Estimates of net atmospheric deposition based on the cores were 3.1 μg m -2 yr -1 for preindustrial and 11.7 μg m -2 yr -1 for modern times. Current-day measurements of wet deposition range from 5.0 to 8.6 μg m -2 yr -1, which are lower than the modern sediment-based estimate of 11.7 μg m -2 yr -1, perhaps owing to inputs of dry-deposited Hg to the lakes.

  18. First approach to the Japanese nitrogen footprint model to predict the loss of nitrogen to the environment

    NASA Astrophysics Data System (ADS)

    Shibata, Hideaki; Cattaneo, Lia R.; Leach, Allison M.; Galloway, James N.

    2014-11-01

    Humans increase the amount of reactive nitrogen (all N species except N2) in the environment through a number of processes, primarily food and energy production. Once in the environment, excess reactive nitrogen may cause a host of various environmental problems. Understanding and controlling individual nitrogen footprints is important for preserving environmental and human health. In this paper we present the per capita nitrogen footprint of Japan. We considered the effect of the international trade of food and feed, and the impact of dietary preferences among different consumer age groups. Our results indicate that the current average per capita N footprint in Japan considering trade is 28.1 kg N capita-1 yr-1. This footprint is dominated by food (25.6 kg N capita-1 yr-1), with the remainder coming from the housing, transportation, and goods and services sectors. The difference in food choices and intake between age groups strongly affected the food N footprint. Younger age groups tend to consume more meat and less fish, which leads to a larger food N footprint (e.g., 27.5 kg N capita-1 yr-1 for ages 20 to 29) than for older age groups (e.g., 23.0 kg N capita-1 yr-1 for ages over 70). The consideration of food and feed imports to Japan reduced the per capita N footprint from 37.0 kg N capita-1 yr-1 to 28.1 kg N capita-1 yr-1. The majority of the imported food had lower virtual N factors (i.e., Nr loss factors for food production), indicating that less N is released to the environment during the respective food production processes. Since Japan relies on imported food (ca. 61%) more than food produced domestically, much of the N losses associated with the food products is released in exporting countries.

  19. Component greenhouse gas fluxes and radiative balance from two deltaic marshes in Louisiana: Pairing chamber techniques and eddy covariance

    NASA Astrophysics Data System (ADS)

    Krauss, Ken W.; Holm, Guerry O.; Perez, Brian C.; McWhorter, David E.; Cormier, Nicole; Moss, Rebecca F.; Johnson, Darren J.; Neubauer, Scott C.; Raynie, Richard C.

    2016-06-01

    Coastal marshes take up atmospheric CO2 while emitting CO2, CH4, and N2O. This ability to sequester carbon (C) is much greater for wetlands on a per area basis than from most ecosystems, facilitating scientific, political, and economic interest in their value as greenhouse gas sinks. However, the greenhouse gas balance of Gulf of Mexico wetlands is particularly understudied. We describe the net ecosystem exchange (NEEc) of CO2 and CH4 using eddy covariance (EC) in comparison with fluxes of CO2, CH4, and N2O using chambers from brackish and freshwater marshes in Louisiana, USA. From EC, we found that 182 g C m-2 yr-1 was lost through NEEc from the brackish marsh. Of this, 11 g C m-2 yr-1 resulted from net CH4 emissions and the remaining 171 g C m-2 yr-1 resulted from net CO2 emissions. In contrast, -290 g C m2 yr-1 was taken up through NEEc by the freshwater marsh, with 47 g C m-2 yr-1 emitted as CH4 and -337 g C m-2 yr-1 taken up as CO2. From chambers, we discovered that neither site had large fluxes of N2O. Sustained-flux greenhouse gas accounting metrics indicated that both marshes had a positive (warming) radiative balance, with the brackish marsh having a substantially greater warming effect than the freshwater marsh. That net respiratory emissions of CO2 and CH4 as estimated through chamber techniques were 2-4 times different from emissions estimated through EC requires additional understanding of the artifacts created by different spatial and temporal sampling footprints between techniques.

  20. Spatially resolving methane emissions in California: constraints from the CalNex aircraft campaign and from present (GOSAT, TES) and future (TROPOMI, geostationary) satellite observations

    NASA Astrophysics Data System (ADS)

    Wecht, K. J.; Jacob, D. J.; Sulprizio, M. P.; Santoni, G. W.; Wofsy, S. C.; Parker, R.; Bösch, H.; Worden, J.

    2014-02-01

    We apply a continental-scale inverse modeling system for North America based on the GEOS-Chem model to optimize California methane emissions at 1/2° × 2/3° horizontal resolution using atmospheric observations from the CalNex aircraft campaign (May-June 2010) and from satellites. Inversion of the CalNex data yields a best estimate for total California methane emissions of 2.86 ± 0.21 Tg yr-1, compared with 1.92 Tg yr-1 in the EDGAR v4.2 emission inventory used as a priori and 1.51 Tg yr-1 in the California Air Resources Board (CARB) inventory used for state regulations of greenhouse gas emissions. These results are consistent with a previous Lagrangian inversion of the CalNex data. Our inversion provides 12 independent pieces of information to constrain the geographical distribution of emissions within California. Attribution to individual source types indicates dominant contributions to emissions from landfills/wastewater (1.1 Tg yr-1), livestock (0.87 Tg yr-1), and gas/oil (0.64 Tg yr-1). EDGAR v4.2 underestimates emissions from livestock while CARB underestimates emissions from landfills/wastewater and gas/oil. Current satellite observations from GOSAT can constrain methane emissions in the Los Angeles Basin but are too sparse to constrain emissions quantitatively elsewhere in California (they can still be qualitatively useful to diagnose inventory biases). Los Angeles Basin emissions derived from CalNex and GOSAT inversions are 0.42 ± 0.08 and 0.31 ± 0.08, respectively. An observation system simulation experiment (OSSE) shows that the future TROPOMI satellite instrument (2015 launch) will be able to constrain California methane emissions at a detail comparable to the CalNex aircraft campaign. Geostationary satellite observations offer even greater potential for constraining methane emissions in the future.