Slice & Dice: Identifying and Removing Bright Galactic Binaries from LISA Data

Here we describe a hierarchal and iterative data analysis algorithm used for searching, characterizing, and removing bright, monochromatic binaries from the Laser Interferometer Space Antenna (LISA) data streams. The algorithm uses the F-statistic to provide an initial solution for individual bright sources, followed by an iterative least squares fitting for all the bright sources. Using the above algorithm, referred to as Slice & Dice, we demonstrate the removal of multiple, correlated galactic binaries from simulated LISA data. Initial results indicate that Slice & Dice may be a useful tool for analyzing the forthcoming LISA data.Comment: 5 pages, 4 figures, proceedings paper for the Sixth International LISA Symposiu

The Effect of NAG–thiazoline on Morphology and Surface Hydrophobicity of Escherichia Coli

The β-hexosaminidase inhibitor and structural analog of the putative oxazolium reaction intermediate of lytic transglycosylases, N-acetylglucosamine thiazoline (NAG–thiazoline), was synthesized in 46% overall yield and tested as an inhibitor of Escherichia coli growth. NAG–thiazoline, at concentrations up to 1 mg/ml, was not found to affect the viability of E. coli DH5α

The determinants of airport hub locations, service, and competition

Although the airline industry has been studied extensively since passage of the Airline Deregulation Act of 1978, relatively little effort has gone into examining how hub location affects the level of service and degree of competition found at airports in the system. To help close this gap, we investigate the geographic distribution of airline hub operations, the level of service, and the extent of competition at 112 major U.S. airports, extending previous work by Bauer (1987) and Butler and Huston (1989). Our key innovation is that we derive our measures of service and competition from indicator matrices that describe each airline's route system.Airlines

U.S. air passenger service: a taxonomy of route networks, hub locations, and competition

In this paper, we analyze the service provided by the 13 largest U.S. passenger airlines to the 100 most populous U.S. metropolitan areas in 1989. We classify the route systems by their nature and geographical extent using a variety of measures based on route-level data. We then identify individual airline hub locations and derive and calculate several measures of the extent of competition both on individual routes and at the airports in our sample. The results show the wide diversity of route networks that existed in the airline industry in 1989--a phenomenon that may help to explain the failure of several major carriers since then.Airlines

Catching Super Massive Black Hole Binaries Without a Net

The gravitational wave signals from coalescing Supermassive Black Hole Binaries are prime targets for the Laser Interferometer Space Antenna (LISA). With optimal data processing techniques, the LISA observatory should be able to detect black hole mergers anywhere in the Universe. The challenge is to find ways to dig the signals out of a combination of instrument noise and the large foreground from stellar mass binaries in our own galaxy. The standard procedure of matched filtering against a grid of templates can be computationally prohibitive, especially when the black holes are spinning or the mass ratio is large. Here we develop an alternative approach based on Metropolis-Hastings sampling and simulated annealing that is orders of magnitude cheaper than a grid search. We demonstrate our approach on simulated LISA data streams that contain the signals from binary systems of Schwarzschild Black Holes, embedded in instrument noise and a foreground containing 26 million galactic binaries. The search algorithm is able to accurately recover the 9 parameters that describe the black hole binary without first having to remove any of the bright foreground sources, even when the black hole system has low signal-to-noise.Comment: 4 pages, 3 figures, Refined search algorithm, added low SNR exampl

Detecting Galactic Binaries with LISA

One of the main sources of gravitational waves for the LISA space-borne interferometer are galactic binary systems. The waveforms for these sources are represented by eight parameters, of which four are extrinsic, and four are intrinsic to the system. Geometrically, these signals exist in an 8-d parameter space. By calculating the metric tensor on this space, we calculate the number of templates needed to search for such sources. We show in this study that below a particular monochromatic frequency, we can ignore one of the intrinsic parameters and search over a 7-d space. Beyond this frequency, we have a sudden change in dimensionality of the parameter space from 7 to 8 dimensions, which results in a change in the scaling of the growth of template number as a function of monochromatic frequency.Comment: 7 pages-2 figures. One figure added and typos corrected. Accepted for the proceedings of GWDAW 9, special edition of Classical and Quantum Gravit

The effect of ruminal and duodenal application of different levels of calcium and phosphorus to sheep on semi-purified diets

Nege behandelings van CaoPo, Car, Cad, Pd, (CAP)r, CadPr, (CaP)d en CarPd (o = geen supplementasie; r -= aan rumen en d = aan duodenum) is ondersoek. P-supplementasie onderdruk Ca-absorpsie en -retensie en omgekeerd. P-absorpsie in duodenum is konsentrasie-afhanklik en Ca- en anolgllniese P-konsentrasie in die rumen is afhanklik van die inname: Ca meer so as P. Serum-Ca was betreklik konstant terwyl serum anorganiese P (Pi) beduidend deur die behandelings beinvloed is. Ca- en P-onderhoudsbehoeftes kan as 3,0 en 1,8 g/dag en die totale endogene verlies 0,5 en ongeveer 0,34 g/dag onderskeidelik beskou word. Die Ca/p verhouding vir die rumen-mikro-organismes is nie kritiesnie maar die Ca-peil mag gewoonweg meer krities as die P-peil in die rumen wees. 'n'Wye Ca/P verhouding vir herkouers is aan te beveel. Konsentrasiesvan Pi en vetsure in rumenvloeistof is betekenisvol gekorreleerd sowel as rumen-Ca met vetsure en TCA-N.The effect of different levels and combinations of Ca and P consisting of nine treatments as CaoPo, Car, Pr,Cad, Pd, (CaP)r, CadPr, (CaP)d and CarPd were investigated with an unrestricted semi-purified diet (r = to the rumen; d = to the duodenum, and o = no supplementation). P supplementation, irrespective of site, depressed Ca absorption and retention and vice versa. P absorption is favoured by high concentrations in the duodenum, absorption thus being concentration dependent. Ca and inorganic P (Pi) concentration in rumen liquor isintake dependent; the former more so than the latter. The serum Ca was relatively stable despite treatment differences, whereas serum Pi concentrationwas significantly affected by treatments. Serum Ca and Pi are negatively correlated (r = -0,5307). Car resulted in the highest concentrationof serum Ca but depressed serum Pi more effectively than e.g. CaoPo and Cad. The Ca and P maintenance requirements were found to be 3,0 and 1,8 g/day and the endogenous loss 0,5 and approximately 0,34 g/day respectively. The Ca/P ratio for the rumen microorganisms is not critical but the rumen Ca level may usually be of a more critical nature in contrast to rumen Pi levels, and thus, favouring a wider ratio than is usually recommended for non-ruminants. Concentrations of rumen liquor Pi and VFA were found to be significantly associated as well as rumen Ca with VFA and TCA-N, respectively.

An adjoint for likelihood maximization

The process of likelihood maximization can be found in many different areas of computational modelling. However, the construction of such models via likelihood maximization requires the solution of a difficult multi-modal optimization problem involving an expensive O(n3) factorization. The optimization techniques used to solve this problem may require many such factorizations and can result in a significant bottle-neck. This article derives an adjoint formulation of the likelihood employed in the construction of a kriging model via reverse algorithmic differentiation. This adjoint is found to calculate the likelihood and all of its derivatives more efficiently than the standard analytical method and can therefore be utilised within a simple local search or within a hybrid global optimization to accelerate convergence and therefore reduce the cost of the likelihood optimization