Computing waveforms for spinning compact binaries in quasi-eccentric orbits

Several scenarios have been proposed in which the orbits of binary black holes enter the band of a gravitational wave detector with significant eccentricity. To avoid missing these signals or biasing parameter estimation it is important that we consider waveform models that account for eccentricity. The ingredients needed to compute post-Newtonian (PN) waveforms produced by spinning black holes inspiralling on quasi-eccentric orbits have been available for almost two decades at 2 PN order, and this work has recently been extended to 2.5 PN order. However, the computational cost of directly implementing these waveforms is high, requiring many steps per orbit to evolve the system of coupled differential equations. Here we employ the standard techniques of a separation of timescales and a generalized Keplerian parameterization of the orbits to produce efficient waveforms describing spinning black hole binaries with arbitrary masses and spins on quasi-eccentric orbits to 1.5 PN order. We separate the fast orbital timescale from the slow spin-orbit precession timescale by solving for the orbital motion in a non-interial frame of reference that follows the orbital precession. We outline a scheme for extending our approach to higher post-Newtonian order.Comment: 11 pages, introduction and references update

Computer program for numerical analysis of stiffened shells of revolution

Programs, using Love-Reissner first-order shell theory, can analyze orthotropic thin shells of revolution subjected to unsymmetric distributed loading or concentrated line loads and thermal strains. They can perform stability or vibration analysis of thin shells of revolution subjected to axisymmetric distributed loading or concentrated line loads and thermal strains

Flammability study of materials in oxygen environments

Report presents flame-propagation rates and flammability ratings of 780 specimens of commercially available plastics, elastomers, coatings, fabrics, and other sheet materials. Test results are also given for over 1970 samples of most commonly used electrical harnesses, connectors, and potting compounds

RISK AND STRUCTURAL CHANGE IN AGRICULTURE: HOW INCOME SHOCKS INFLUENCE FARM SIZE

Farm-level Census data and county-level income shock data reveal that past unexpected income shocks affect the rate of change in average farm size. Average farm size increases more quickly in counties experiencing negative income shocks as compared to counties experiencing positive income shocks. This result cannot be explained by perfect-market models, which predict farm size should adjust according to changes in the relative prices of labor and capital. We posit a model wherein cash flows affect liquidity, which in turn affects farm borrowing and capital costs. In the model, farms that do not face liquidity constraints benefit from negative income shocks because they reduce land values, so these farms expand while liquidity-constrained farms contract. Observed farm consolidation patterns and farm exit rates are consistent with a model wherein liquidity constraints affect small farms more than large farms.farm size, farm structure, income shocks, liquidity constraint, risk, Agricultural Finance, Industrial Organization,

High-Pressure Oxygen Test Evaluations

The relevance of impact sensitivity testing to the development of the space shuttle main engine is discussed in the light of the special requirements for the engine. The background and history of the evolution of liquid and gaseous oxygen testing techniques and philosophy is discussed also. The parameters critical to reliable testing are treated in considerable detail, and test apparatus and procedures are described and discussed. Materials threshold sensitivity determination procedures are considered and a decision logic diagram for sensitivity threshold determination was plotted. Finally, high-pressure materials sensitivity test data are given for selected metallic and nonmetallic materials

Commodity Payments, Farm Business Survival, and Farm Size Growth

In the last 25 years, U.S. crop farms have steadily declined in number and grown in average size, as production has shifted to larger operations. Larger farms tend to receive more commodity program payments because most payments are tied to a farm’s current or historical production, but whether payments have contributed to farm growth is uncertain. This study uses farm-level data from the census of agriculture to determine whether there is a statistical relationship between farm commodity program payments and greater concentration in production. The analysis indicates that, at the regional level, higher commodity program payments per acre are associated with subsequent farm growth. Also, higher payments per acre are associated with higher rates of farm survival and growth.agricultural payments, farm size, farm survival, concentration, consolidation, government payments, commodity programs., Agribusiness, Agricultural and Food Policy, Community/Rural/Urban Development, Crop Production/Industries, Farm Management,

Does risk matter for farm businesses? The effect of crop insurance on production and diversification.

We use a large increase in Federal crop insurance subsidies as a natural experiment to identify the impact of risk on acreage and diversification decisions. Subsidy increases induced greater crop insurance coverage, which reduced farmers' financial risks. Did this change in the risk environment alter production decisions? We merged crop insurance participation data with farm-level Agricultural Census data from 1992 and 1997 to examine how harvested acreage and diversification changed in response to the policy-induced change in insurance coverage. The difference in differences empirical approach controls for unobservable heterogeneity and our results are robust across multiple definitions of our key variables and various fixed effects. We find that changes in the risk environment caused larger farms to expand while smaller farms shrank. Regardless of size, producers showed some evidence of using diversification as a method to mitigate risk. However, risk does not seem to have large overall effects.Risk and Uncertainty,

Characterizing Spinning Black Hole Binaries in Eccentric Orbits with LISA

The Laser Interferometer Space Antenna (LISA) is designed to detect gravitational wave signals from astrophysical sources, including those from coalescing binary systems of compact objects such as black holes. Colliding galaxies have central black holes that sink to the center of the merged galaxy and begin to orbit one another and emit gravitational waves. Some galaxy evolution models predict that the binary black hole system will enter the LISA band with significant orbital eccentricity, while other models suggest that the orbits will already have circularized. Using a full seventeen parameter waveform model that includes the effects of orbital eccentricity, spin precession and higher harmonics, we investigate how well the source parameters can be inferred from simulated LISA data. Defining the reference eccentricity as the value one year before merger, we find that for typical LISA sources, it will be possible to measure the eccentricity to an accuracy of parts in a thousand. The accuracy with which the eccentricity can be measured depends only very weakly on the eccentricity, making it possible to distinguish circular orbits from those with very small eccentricities. LISA measurements of the orbital eccentricity can help constraints theories of galaxy mergers in the early universe. Failing to account for the eccentricity in the waveform modeling can lead to a loss of signal power and bias the estimation of parameters such as the black hole masses and spins.Comment: 11 pages, 13 figures, references, text and figures update

Time to publication for NIHR HTA programme-funded research: a cohort study

ObjectiveTo assess the time to publication of primary research and evidence syntheses funded by the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) Programme published as a monograph in Health Technology Assessment and as a journal article in the wider biomedical literature.Study designRetrospective cohort study.SettingPrimary research and evidence synthesis projects funded by the HTA Programme were included in the cohort if they were registered in the NIHR research programmes database and was planned to submit the draft final report for publication in Health Technology Assessment on or before 9 December 2011.Main outcome measuresThe median time to publication and publication at 30?months in Health Technology Assessment and in an external journal were determined by searching the NIHR research programmes database and HTA Programme website.ResultsOf 458 included projects, 184 (40.2%) were primary research projects and 274 (59.8%) were evidence syntheses. A total of 155 primary research projects had a completion date; the median time to publication was 23?months (26.5 and 35.5?months to publish a monograph and to publish in an external journal, respectively) and 69% were published within 30?months. The median time to publication of HTA-funded trials (n=126) was 24?months and 67.5% were published within 30?months. Among the evidence syntheses with a protocol online date (n=223), the median time to publication was 25.5?months (28?months to publication as a monograph), but only 44.4% of evidence synthesis projects were published in an external journal. 65% of evidence synthesis studies had been published within 30.0?months.ConclusionsResearch funded by the HTA Programme publishes promptly. The importance of Health Technology Assessment was highlighted as the median time to publication was 9?months shorter for a monograph than an external journal article

Sea ice - atmosphere interaction: Application of multispectral satellite data in polar surface energy flux estimates

In the past six months, work has continued on energy flux sensitivity studies, ice surface temperature retrievals, corrections to Advanced Very High Resolution Radiometer (AVHRR) thermal infrared data, modelling of cloud fraction retrievals, and radiation climatologies. We tentatively conclude that the SSM/I may not provide accurate enough estimates of ice concentration and type to improve our shorter term energy flux estimates. SSM/I derived parameters may still be applicable in longer term climatological flux characterizations. We hold promise for a system coupling observation to a ice deformation model. Such a model may provide information on ice distribution which can be used in energy flux calculations. Considerable variation was found in modelled energy flux estimates when bulk transfer coefficients are modulated by lead fetch. It is still unclear what the optimum formulation is and this will be the subject of further work. Data sets for ice surface temperature retrievals were assembled and preliminary data analysis was started. Finally, construction of a conceptual framework for further modelling of the Arctic radiation flux climatology was started