Gravitational Wave Chirp Search: Economization of PN Matched Filter Bank via Cardinal Interpolation

The final inspiral phase in the evolution of a compact binary consisting of black holes and/or neutron stars is among the most probable events that a network of ground-based interferometric gravitational wave detectors is likely to observe. Gravitational radiation emitted during this phase will have to be dug out of noise by matched-filtering (correlating) the detector output with a bank of several $10^5$ templates, making the computational resources required quite demanding, though not formidable. We propose an interpolation method for evaluating the correlation between template waveforms and the detector output and show that the method is effective in substantially reducing the number of templates required. Indeed, the number of templates needed could be a factor $\sim 4$ smaller than required by the usual approach, when the minimal overlap between the template bank and an arbitrary signal (the so-called {\it minimal match}) is 0.97. The method is amenable to easy implementation, and the various detector projects might benefit by adopting it to reduce the computational costs of inspiraling neutron star and black hole binary search.Comment: scheduled for publicatin on Phys. Rev. D 6

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

A Proposed Method for Monitoring U.S. Population Health: Linking Symptoms, Impairments, and Health Ratings

We propose a method of quantifying non-fatal health on a 0-1 QALY scale that details the impact of specific symptoms and impairments and is not based on ratings of counterfactual scenarios. Measures of general health status are regressed on health impairments and symptoms in different domains, using ordered probit and ordinary least squares regression. This yields estimates of their effects analogous to disutility weights, and accounts for complex non-additive relationships. Health measures used include self-rated health status on a 5-point scale, EuroQol 5D (EQ-5D) scores, and ratings of current health using a 0-100 rating scale and a time-tradeoff. Data are from the nationally representative Medical Expenditure Panel Survey (MEPS) year 2002 (N=34,615), with validation in an independent sample from MEPS 2000 (N=21,067) and among 1420 adults age 45-89 in the Beaver Dam Health Outcomes Study. Decrement weights for symptoms and impairments are used to derive estimates of overall health-related quality of life, laying the groundwork for a detailed national summary measure of health. To purchase a copy of the earlier version of this paper, please contact the Working Papers department directly at (617) 588 1405.

English-learning infants’ perception of word stress patterns

Adult speakers of different free stress languages (e.g., English, Spanish) differ both in their sensitivity to lexical stress and in their processing of suprasegmental and vowel quality cues to stress. In a head-turn preference experiment with a familiarization phase, both 8-month-old and 12-month-old English-learning infants discriminated between initial stress and final stress among lists of Spanish-spoken disyllabic nonwords that were segmentally varied (e.g. [ˈnila, ˈtuli] vs [luˈta, puˈki]). This is evidence that English-learning infants are sensitive to lexical stress patterns, instantiated primarily by suprasegmental cues, during the second half of the first year of life

Value of Medical Innovation in the United States: 1960-2000

Background: The increased use of medical therapies has led to increased medical costs. To provide insight into the value of this increased spending, we compared gains in life expectancy with the increased costs of care from 1960 through 2000. Methods: We estimated life expectancy in 1960, 1970, 1980, 1990, and 2000 for four age groups. To control for the influence of nonmedical factors on survival, we assumed in our base-case analysis that 50 percent of the gains were due to medical care. We compared the adjusted increases in life expectancy with the lifetime cost of medical care in the same years. Results: From 1960 through 2000, the life expectancy for newborns increased by 6.97 years, lifetime medical spending adjusted for inflation increased by approximately $69,000, and the cost per year of life gained was$19,900. The cost increased from $7,400 per year of life gained in the 1970s to$36,300 in the 1990s. The average cost per year of life gained in 1960–2000 was approximately $31,600 at 15 years of age,$53,700 at 45 years of age, and $84,700 at 65 years of age. At 65 years of age, costs rose more rapidly than did life expectancy: the cost per year of life gained was$121,000 between 1980 and 1990 and $145,000 between 1990 and 2000. Conclusions: On average, the increases in medical spending since 1960 have provided reasonable value. However, the spending increases in medical care for the elderly since 1980 are associated with a high cost per year of life gained. The national focus on the rise in medical spending should be balanced by attention to the health benefits of this increased spending.Economic

Speeded detection of vowels and steady-state consonants

We report two experiments in which vowels and steady-state consonants served as targets in a speeded detection task. In the first experiment, two vowels were compared with one voiced and once unvoiced fricative. Response times (RTs) to the vowels were longer than to the fricatives. The error rate was higher for the consonants. Consonants in word-final position produced the shortest RTs, For the vowels, RT correlated negatively with target duration. In the second experiment, the same two vowel targets were compared with two nasals. This time there was no significant difference in RTs, but the error rate was still significantly higher for the consonants. Error rate and length correlated negatively for the vowels only. We conclude that RT differences between phonemes are independent of vocalic or consonantal status. Instead, we argue that the process of phoneme detection reflects more finely grained differences in acoustic/articulatory structure within the phonemic repertoire