The generalized F-statistic: multiple detectors and multiple GW pulsars

The F-statistic, derived by Jaranowski, Krolak & Schutz (1998), is the optimal (frequentist) statistic for the detection of nearly periodic gravitational waves from known neutron stars, in the presence of stationary, Gaussian detector noise. The F-statistic was originally derived for the case of a single detector, whose noise spectral density was assumed constant in time, and for a single known neutron star. Here we show how the F-statistic can be straightforwardly generalized to the cases of 1) a network of detectors with time-varying noise curves, and 2) a population of known sources. Fortunately, all the important ingredients that go into our generalized F-statistics are already calculated in the single-source/single-detector searches that are currently implemented, e.g., in the LIGO Software Library, so implementation of optimal multi-detector, multi-source searches should require negligible additional cost in computational power or software development.Comment: 6 pages, 0 figures, submitted to PRD; section IV substantially enlarged and revised, and a few typos correcte

Macroeconomic Performance and the Disadvantaged

macroeconomics

Discrimination of unique biological communities in the Mississippi lignite belt

Small scale hardcopy LANDSAT prints were manually interpreted and color infrared aerial photography was obtained in an effort to identify and map large contiguous areas of old growth hardwood stands within Mississippi's lignite belt which do not exhibit signs of recent disturbance by agriculture, grazing, timber harvesting, fire, or any natural catastrophe, and which may, therefore, contain unique or historical ecological habitat types. An information system using land cover classes derived from digital LANDSAT data and containing information on geology, hydrology, soils, and cultural activities was developed. Using computer-assisted land cover classifications, all hardwood remnants in the study area which are subject to possible disturbance from surface mining were determined. Twelve rare plants were also identified by botanists

Coping with speaker-related variation via abstract phonemic categories

Listeners can cope with considerable variation in the way that different speakers talk. We argue here that they can do so because of a process of phonological abstraction in the speech-recognition system. We review evidence that listeners adjust the bounds of phonemic categories after only very limited exposure to a deviant realisation of a given phoneme. This learning can be talker-specific and is stable over time; further, the learning generalizes to previously unheard words containing the deviant phoneme. Together these results suggest that the learning involves adjustment of prelexical phonemic representations which mediate between the speech signal and the mental lexicon during word recognition. We argue that such an abstraction process is inconsistent with claims made by some recent models of language processing that the mental lexicon consists solely of multiple detailed traces of acoustic episodes. Simulations with a purely episodic model without functional prelexical abstraction confirm that such a model cannot account for the evidence on lexical generalization of perceptual learning. We conclude that abstract phonemic categories form a necessary part of lexical access, and that the ability to store talker-specific knowledge about those categories provides listeners with the means to deal with cross-talker variation

Angular Resolution of the LISA Gravitational Wave Detector

We calculate the angular resolution of the planned LISA detector, a space-based laser interferometer for measuring low-frequency gravitational waves from galactic and extragalactic sources. LISA is not a pointed instrument; it is an all-sky monitor with a quadrupolar beam pattern. LISA will measure simultaneously both polarization components of incoming gravitational waves, so the data will consist of two time series. All physical properties of the source, including its position, must be extracted from these time series. LISA's angular resolution is therefore not a fixed quantity, but rather depends on the type of signal and on how much other information must be extracted. Information about the source position will be encoded in the measured signal in three ways: 1) through the relative amplitudes and phases of the two polarization components, 2) through the periodic Doppler shift imposed on the signal by the detector's motion around the Sun, and 3) through the further modulation of the signal caused by the detector's time-varying orientation. We derive the basic formulae required to calculate the LISA's angular resolution $\Delta \Omega_S$ for a given source. We then evaluate $\Delta \Omega_S$ for two sources of particular interest: monchromatic sources and mergers of supermassive black holes. For these two types of sources, we calculate (in the high signal-to-noise approximation) the full variance-covariance matrix, which gives the accuracy to which all source parameters can be measured. Since our results on LISA's angular resolution depend mainly on gross features of the detector geometry, orbit, and noise curve, we expect these results to be fairly insensitive to modest changes in detector design that may occur between now and launch. We also expect that our calculations could be easily modified to apply to a modified design.Comment: 15 pages, 5 figures, RevTex 3.0 fil

RGS4 controls secretion of von Willebrand factor to the subendothelial matrix

The haemostatic protein von Willebrand Factor (VWF) exists in plasma and subendothelial pools; the former secreted from endothelial storage granules, Weibel-Palade bodies (WPBs), by basal secretion with a contribution from agonist-stimulated secretion, the latter secreted into the subendothelial matrix by a constitutive pathway, not involving WPBs. We set out to determine if the constitutive release of subendothelial VWF is actually regulated and if so, what functional consequences this might have. Constitutive VWF secretion can be increased by a range of factors; changes in VWF expression, levels of TNF-alpha or other environmental cues. An RNAseq analysis revealed that expression of RGS4 (Regulator of G protein signalling 4) was reduced in endothelial cells (HUVECs) grown under these conditions. si-RGS4 treatment of HUVECs increased constitutive basolateral secretion of VWF, probably by affecting the anterograde secretory pathway. In a simple model of endothelial damage we show that RGS4-silenced cells increased platelet recruitment onto the subendothelial matrix under flow. These results show that changes in RGS4 expression alter levels of subendothelial VWF, affecting platelet recruitment. This introduces a novel control over VWF function

Rising Inequality? Changes in the Distribution of Income and Consumption in the 1980s

This paper examines changes in the distribution of income and consumption in the United States during the 1980s. using data from the Current Population Survey (income) and Consumer Expenditure Survey (consumption). We reach three primary conclusions. First. changes in the distribution of consumption parallel changes in the distribution of income. The lowest quintile of the consumption distribution received 0.9 percentage points less of total consumption in 1988 than in 1980; the corresponding decline for income was 0.6 percentage points. Second. broad conclusions concerning recent changes in the consumption distribution are not very sensitive to the exact choice of a measure of family needs. Under a wide variety of alternative household equivalence scales. there is a widening in the consumption distribution in the 1980s. Third. the usc of consumption measures of well-being in place of measures based on current money income docs change conclusions concerning the extent of poverty in the United Stales. Using the official federal poverty thresholds. we find that the overall consumption poverty rate was three percentage points below the income poverty rate in 1988. Comparisons of the poverty rates of the elderly and the non-elderly are substantially affected by the choice of poverty measure. The consumption poverty rare for the elderly was only 60 percent of the rate for adults and one-third of the rate for children in 1988.