9,446 research outputs found

    Relative annoyance and loudness judgements of various simulated sonic boom waveforms

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    Effects of various simulated sonic boom waveforms on human subjective respons

    The APM Galaxy Survey III: An Analysis of Systematic Errors in the Angular Correlation Function and Cosmological Implications

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    We present measurements of the angular two-point galaxy correlation function, w(theta)w(theta), from the APM Galaxy Survey. The performance of various estimators of ww is assessed using simulated galaxy catalogues and analytic arguments. Several error analyses show that residual plate-to-plate errors do not bias our estimates of ww by more than 10−310^{-3}. Direct comparison between our photometry and external CCD photometry of over 13,000 galaxies from the Las Campanas Deep Redshift Survey shows that the rms error in the APM plate zero points lies in the range 0.04-0.05 magnitudes, in agreement with our previous estimates. We estimate the effects on ww of atmospheric extinction and obscuration by dust in our Galaxy and conclude that these are negligible. We use our best estimates of the systematic errors in the survey to calculate corrected estimates of ww. Deep redshift surveys are used to determine the selection function of the APM Galaxy Survey, and this is applied in Limber's equation to compute how ww scales as a function of limiting magnitude. Our estimates of ww are in excellent agreement with the scaling relation, providing further evidence that systematic errors in the APM survey are small. We explicitly remove large-scale structure by applying filters to the APM galaxy maps and conclude that there is still strong evidence for more clustering at large scales than predicted by the standard scale-invariant cold dark matter (CDM) model. We compare the APM ww and the three dimensional power spectrum derived by inverting ww, with the predictions of scale-invariant CDM models. We show that the observations require Gamma=Omega0hGamma=Omega_0 h in the range 0.2-0.3 and are incompatible with the value Gamma=0.5Gamma=0.5 of the standard CDM model.Comment: 102 pages, plain TeX plus 41 postscript figures. Submitted to MNRA

    The Apm Galaxy Survey IV: Redshifts of Rich Clusters of Galaxies

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    We present redshifts for a sample of 229 clusters selected from the APM Galaxy Survey, 189 of which are new redshift determinations. Non-cluster galaxy redshifts have been rejected from this sample using a likelihood ratio test based on the projected and apparent magnitude distributions of the cluster fields. We test this technique using cluster fields in which redshifts have been measured for more than 10 galaxies. Our redshift sample is nearly complete and has been used in previous papers to study the three dimensional distribution of rich clusters of galaxies. 157 of the clusters in our sample are listed in the Abell catalogue or supplement, and the remainder are new cluster identifications.Comment: 15 pages UUencoded compressed postscript. Submitted to Monthly Notices of the R.A.

    Genomic regions associated with common root rot resistance in the barley variety Delta

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    Common root rot (CRR) caused by Bipolaris sorokiniana is a serious disease constraint in the dry temperate cereal growing regions of the world. Currently little is known about the genetic control of resistance to CRR in cereals. In this study based on a Delta/Lindwall barley population we have undertaken a bulked segregant analysis (BSA) and whole genome mapping approach utilising Diversity Arrays Technology (DArT) to identified quantitative trait loci (QTL) associated with CRR expression. One QTL each was identified on chromosomes 4HL and 5HL explaining 12 and 11% of the phenotypic variance, respectively

    Disagreement between calorimetric and van't Hoff enthalpies of assembly of protein supramolecular structures.

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    Conservation laws in the continuum 1/r21/r^2 systems

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    We study the conservation laws of both the classical and the quantum mechanical continuum 1/r21/r^2 type systems. For the classical case, we introduce new integrals of motion along the recent ideas of Shastry and Sutherland (SS), supplementing the usual integrals of motion constructed much earlier by Moser. We show by explicit construction that one set of integrals can be related algebraically to the other. The difference of these two sets of integrals then gives rise to yet another complete set of integrals of motion. For the quantum case, we first need to resum the integrals proposed by Calogero, Marchioro and Ragnisco. We give a diagrammatic construction scheme for these new integrals, which are the quantum analogues of the classical traces. Again we show that there is a relationship between these new integrals and the quantum integrals of SS by explicit construction.Comment: 19 RevTeX 3.0 pages with 2 PS-figures include

    Why is timing of bird migration advancing when individuals are not?

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    Recent advances in spring arrival dates have been reported in many migratory species but the mechanism driving these advances is unknown. As population declines are most widely reported in species that are not advancing migration, there is an urgent need to identify the mechanisms facilitating and constraining these advances. Individual plasticity in timing of migration in response to changing climatic conditions is commonly proposed to drive these advances but plasticity in individual migratory timings is rarely observed. For a shorebird population that has significantly advanced migration in recent decades, we show that individual arrival dates are highly consistent between years, but that the arrival dates of new recruits to the population are significantly earlier now than in previous years. Several mechanisms could drive advances in recruit arrival, none of which require individual plasticity or rapid evolution of migration timings. In particular, advances in nest-laying dates could result in advanced recruit arrival, if benefits of early hatching facilitate early subsequent spring migration. This mechanism could also explain why arrival dates of short-distance migrants, which generally return to breeding sites earlier and have greater scope for advance laying, are advancing more rapidly than long-distance migrants

    RBSC-NVSS Sample. I. Radio and Optical Identifications of a Complete Sample of 1500 Bright X-ray Sources

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    We cross-identified the ROSAT Bright Source Catalog (RBSC) and the NRAO VLA Sky Survey (NVSS) to construct the RBSC-NVSS sample of the brightest X-ray sources (>= 0.1 counts/s or ~1E-12 ergs/cm/cm/s in the 0.1-2.4 keV band) that are also radio sources (S >= 2.5 mJy at 1.4 GHz) in the 7.8 sr of extragalactic sky with |b| > 15 degrees. and delta > -40 degrees. The sky density of NVSS sources is low enough that they can be reliably identified with RBSC sources having average rms positional uncertainties = 10 arcsec. We used the more accurate radio positions to make reliable X-ray/radio/optical identifications down to the POSS plate limits. We obtained optical spectra for many of the bright identifications lacking published redshifts. The resulting X-ray/radio sample is unique in its size (N ~ 1500 objects), composition (a mixture of nearly normal galaxies, Seyfert galaxies, quasars, and clusters), and low average redshift ( ~ 0.1).Comment: 35 LaTeX pages including 6 eps figures + 40 LaTeX page table2 (landscape) w/ AASTeX 5.0; accepted to ApJ
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