PubMed Journals Articles About "NASA Extends Aircraft Maintenance Contract"

Formation and spread of aircraft-induced holes in clouds.

Hole-punch and canal clouds have been observed for more than 50 years, but the mechanisms of formation, development, duration, and thus the extent of their effect have largely been ignored. The holes have been associated with inadvertent seeding of clouds with ice particles generated by aircraft, produced through spontaneous freezing of cloud droplets in air cooled as it flows around aircraft propeller tips or over jet aircraft wings. Model simulations indicate that the growth of the ice particles can induc...

Aircraft Emissions of Methane and Nitrous Oxide during the Alternative Aviation Fuel Experiment.

Given the predicted growth of aviation and the recent developments of alternative aviation fuels, quantifying methane (CH(4)) and nitrous oxide (N(2)O) emission ratios for various aircraft engines and fuels can help constrain projected impacts of aviation on the Earth's radiative balance. Fuel-based emission indices for CH(4) and N(2)O were quantified from CFM56-2C1 engines aboard the NASA DC-8 aircraft during the first Alternative Aviation Fuel Experiment (AAFEX-I) in 2009. The measurements of JP-8 fuel co...

Planetary science. Probing an extrasolar planet.

Planetary science: A cloudy view of exoplanets.

CO(2), NO(x), and Particle Emissions from Aircraft and Support Activities at a Regional Airport.

The goal of this research was to quantify emissions of carbon dioxide (CO(2)), nitrogen oxides (NO(x)), particle number, and black carbon (BC) from in-use aircraft and related activity at a regional airport. Pollutant concentrations were measured adjacent to the airfield and passenger terminal at the Roanoke Regional Airport in Virginia. Observed NO(x) emission indices (EIs) for jet-powered, commuter aircraft were generally lower than those contained in the International Civil Aviation Organization databank...

Processes that Drove the Transition from Chemistry to Biology: Concepts and Evidence.

Global Mortality Attributable to Aircraft Cruise Emissions.

Aircraft emissions impact human health though degradation of air quality. The majority of previous analyses of air quality impacts from aviation have considered only landing and takeoff emissions. We show that aircraft cruise emissions impact human health over a hemispheric scale and provide the first estimate of premature mortalities attributable to aircraft emissions globally. We estimate approximately 8000 premature mortalities per year are attributable to aircraft cruise emissions. This represents appro...

Occupational aviation fatalities --- alaska, 2000--2010.

Aircraft crashes are the second leading cause of occupational deaths in Alaska; during the 1990s, a total of 108 fatal aviation crashes resulted in 155 occupational fatalities. To update data and identify risk factors for occupational death from aircraft crashes, CDC reviewed data from the National Transportation Safety Board (NTSB) and the Alaska Occupational Injury Surveillance System. During 2000--2010, a total of 90 occupational fatalities occurred as a result of 54 crashes, an average of five fatal air...

Characterization of lubrication oil emissions from aircraft engines.

In this first ever study, particulate matter (PM) emitted from the lubrication system overboard breather vent for two different models of aircraft engines has been systematically characterized. Lubrication oil was confirmed as the predominant component of the emitted particulate matter based upon the characteristic mass spectrum of the pure oil. Total particulate mass and size distributions of the emitted oil are also investigated by several high-sensitivity aerosol characterization instruments. The emissio...

Can labour contract differences in health and work-related attitudes be explained by quality of working life and job insecurity?

STUDY AIM: We hypothesise that due to a lower quality of working life and higher job insecurity, the health and work-related attitudes of temporary workers may be less positive compared to permanent workers. Therefore, we aimed to (1) examine differences between contract groups (i.e. permanent contract, temporary contract with prospect of permanent work, fixed-term contract, temporary agency contract and on-call contract) in the quality of working life, job insecurity, health and work-...

Identification of lubrication oil in the particulate matter emissions from engine exhaust of in-service commercial aircraft.

Lubrication oil was identified in the organic particulate matter (PM) emissions of engine exhaust plumes from in-service commercial aircraft at Chicago Midway Airport (MDW) and O'Hare International Airport (ORD). This is the first field study focused on aircraft lubrication oil emissions, and all of the observed plumes described in this work were due to near-idle engine operations. The identification was carried out with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF AMS) via a...

Preliminary evaluation of evaluation of the efficiency of aircraft liquid waste treatment using resolvable sanitizing liquid: a case study in Changchun.

The physical, chemical, and biological indices of aircraft liquid wastes collected from multiple airplanes at Longjia Airport, Changchun, China were measured according to "Integrated Wastewater Discharge Standard," evaluating treatment efficiency of resolvable sanitizing liquid. The results indicate that, after being treated by the resolvable sanitizing liquid, the indices of all first-class pollutants met the requirements of the standard, while among the second-class pollutants, the suspension content, bio...

Does Traffic-related Air Pollution Explain Associations of Aircraft and Road Traffic Noise Exposure on Children's Health and Cognition? A Secondary Analysis of the United Kingdom Sample From the RANCH Project.

The authors examined whether air pollution at school (nitrogen dioxide) is associated with poorer child cognition and health and whether adjustment for air pollution explains or moderates previously observed associations between aircraft and road traffic noise at school and children's cognition in the 2001-2003 Road Traffic and Aircraft Noise Exposure and Children's Cognition and Health (RANCH) project. This secondary analysis of a subsample of the United Kingdom RANCH sample examined 719 children who were...

Impact of Employment Contract Changes on Workers' Quality of Working Life, Job insecurity, Health and work-related Attitudes.

Objectives: Changes in employment contracts may impact the quality of working life, job insecurity, health and work-related attitudes. We examined the validity of two partly competing theoretical approaches. Based upon a segmentation approach, we expected no change in scores among stable trajectories, whereas upward trajectories were expected to be for the better and downward trajectories to be for the worse (Hypothesis 1). As turnover theories suggest that this hypothesis may only apply to workers who do n...

A Ripple-Spreading Genetic Algorithm for the Aircraft Sequencing Problem.

Abstract When genetic algorithms (GAs) are applied to combinatorial problems, permutation representations are usually adopted. As a result, such GAs are often confronted with feasibility and memory-efficiency problems. With the aircraft sequencing problem (ASP) as a study case, this paper reports on a novel binary-representation-based GA scheme for combinatorial problems. Unlike existing GAs for the ASP, which typically use permutation representations based on aircraft landing order, the new GA introduces a...

Measurements of Nitrous Acid in Commercial Aircraft Exhaust at the Alternative Aviation Fuel Experiment.

The Alternative Aviation Fuel Experiment (AAFEX), conducted in January of 2009 in Palmdale, California, quantified aerosol and gaseous emissions from a DC-8 aircraft equipped with CFM56-2C1 engines using both traditional and synthetic fuels. This study examines the emissions of nitrous acid (HONO) and nitrogen oxides (NO(x) = NO + NO(2)) measured 145 m behind the grounded aircraft. The fuel-based emission index (EI) for HONO increases approximately 6-fold from idle to takeoff conditions but plateaus between...

Is skill mix profitable in the current NHS dental contract in England?

The use of skill mix in medicine is now widespread, yet it appears that its use in dentistry is not as prominent. Unlike doctors, dentists are required to mitigate the financial risk produced by their capital investment and ensure an adequate cash flow to cover their annual running costs. Examining the financial incentives for employing dental care professionals is therefore an important step to understand why dentistry appears to lag behind medicine in skill mix. It is also apposite, given the announcement...

Characteristics of Beneficiaries of a GP-Centred Health Care Contract in Germany.

BACKGROUND AND PURPOSE: : Since 2004, primary care in Germany has increasingly been provided in special general practitioner (GP)-centred health care contracts (HZV). To date there is limited evidence about the characteristics of their beneficiaries regarding morbidity burden and health care utilization. METHODS: : We analysed insurance claims data from all beneficiaries of the "Allgemeine Ortskrankenkasse (AOK) Baden-Württemberg" listed in 10 general practices that contracted in a special GP-centred healt...

Workload assessment of surgeons: correlation between NASA TLX and blinks.

BACKGROUND: Blinks are known as an indicator of visual attention and mental stress. In this study, surgeons' mental workload was evaluated utilizing a paper assessment instrument (National Aeronautics and Space Administration Task Load Index, NASA TLX) and by examining their eye blinks. Correlation between these two assessments was reported. METHODS: Surgeons' eye motions were video-recorded using a head-mounted eye-tracker while the surgeons performed a laparoscopic procedure on a virtual reality trainer....

Neutron diffraction study of water freezing on aircraft engine combustor soot.

The study of the formation of condensation trails and cirrus clouds on aircraft emitted soot particles is important because of its possible effects on climate. In the present work we studied the freezing of water on aircraft engine combustor (AEC) soot particles under conditions of pressure and temperature similar to the upper troposphere. The microstructure of the AEC soot was found to be heterogeneous containing both primary particles of soot and metallic impurities (Fe, Cu, and Al). We also observed vari...

Summary of: Clinical decision making by dentists working in the NHS General Dental Services since April 2006.

In April 2006 a new contract was introduced that governed how NHS General Dental Practitioners would be funded for the services they provide. This study looks at the impact that the contract has had in the three years since its introduction, evaluating its influence on the clinical care that patients receive and the clinical decisions that dentists are making. This qualitative service evaluation involved interviewing 12 dentists representative of a range of NHS dentists working with the new NHS dental contr...

NASA under the spotlight.

Europe makes do without NASA.

Clinical decision making by dentists working in the NHS General Dental Services since April 2006.

(1)In April 2006 a new contract was introduced that governed how NHS General Dental Practitioners would be funded for the services they provide. This study looks at the impact that the contract has had in the three years since its introduction, evaluating its influence on the clinical care that patients receive and the clinical decisions that dentists are making. This qualitative service evaluation involved interviewing 12 dentists representative of a range of NHS dentists involved with the new NHS dental c...

Shuttle's end spells change at NASA.