Science.gov

Sample records for 21-cm detection rate

  1. Gravitational-wave detection using redshifted 21-cm observations

    SciTech Connect

    Bharadwaj, Somnath; Guha Sarkar, Tapomoy

    2009-06-15

    A gravitational-wave traversing the line of sight to a distant source produces a frequency shift which contributes to redshift space distortion. As a consequence, gravitational waves are imprinted as density fluctuations in redshift space. The gravitational-wave contribution to the redshift space power spectrum has a different {mu} dependence as compared to the dominant contribution from peculiar velocities. This, in principle, allows the two signals to be separated. The prospect of a detection is most favorable at the highest observable redshift z. Observations of redshifted 21-cm radiation from neutral hydrogen hold the possibility of probing very high redshifts. We consider the possibility of detecting primordial gravitational waves using the redshift space neutral hydrogen power spectrum. However, we find that the gravitational-wave signal, though present, will not be detectable on superhorizon scales because of cosmic variance and on subhorizon scales where the signal is highly suppressed.

  2. e-MERLIN 21 cm constraints on the mass-loss rates of OB stars in Cyg OB2

    NASA Astrophysics Data System (ADS)

    Morford, J. C.; Fenech, D. M.; Prinja, R. K.; Blomme, R.; Yates, J. A.

    2016-11-01

    We present e-MERLIN 21 cm (L-band) observations of single luminous OB stars in the Cygnus OB2 association, from the Cyg OB2 Radio Survey Legacy programme. The radio observations potentially offer the most straightforward, least model-dependent, determinations of mass-loss rates, and can be used to help resolve current discrepancies in mass-loss rates via clumped and structured hot star winds. We report here that the 21 cm flux densities of O3 to O6 supergiant and giant stars are less than ˜70 μJy. These fluxes may be translated to `smooth' wind mass-loss upper limits of ˜4.4-4.8 × 10-6 M⊙ yr -1 for O3 supergiants and ≲2.9 × 10-6 M⊙ yr -1 for B0 to B1 supergiants. The first ever resolved 21 cm detections of the hypergiant (and luminous blue variable candidate) Cyg OB2 #12 are discussed; for multiple observations separated by 14 d, we detect an ˜69 per cent increase in its flux density. Our constraints on the upper limits for the mass-loss rates of evolved OB stars in Cyg OB2 support the model that the inner wind region close to the stellar surface (where Hα forms) is more clumped than the very extended geometric region sampled by our radio observations.

  3. e-MERLIN 21cm constraints on the mass-loss rates of OB stars in Cyg OB2

    NASA Astrophysics Data System (ADS)

    Morford, J. C.; Fenech, D. M.; Prinja, R. K.; Blomme, R.; Yates, J. A.

    2016-08-01

    We present e-MERLIN 21 cm (L-band) observations of single luminous OB stars in the Cygnus OB2 association, from the COBRaS Legacy programme. The radio observations potentially offer the most straightforward, least model-dependent, determinations of mass-loss rates, and can be used to help resolve current discrepancies in mass-loss rates via clumped and structured hot star winds. We report here that the 21 cm flux densities of O3 to O6 supergiant and giant stars are less than ˜ 70 μJy. These fluxes may be translated to `smooth' wind mass-loss upper limits of ˜ 4.4 - 4.8 × 10-6 M⊙ yr -1 for O3 supergiants and ≲ 2.9 × 10-6 M⊙ yr -1 for B0 to B1 supergiants. The first ever resolved 21 cm detections of the hypergiant (and LBV candidate) Cyg OB2 #12 are discussed; for multiple observations separated by 14 days, we detect a ˜ 69% increase in its flux density. Our constraints on the upper limits for the mass-loss rates of evolved OB stars in Cyg OB2 support the model that the inner wind region close to the stellar surface (where Hα forms) is more clumped than the very extended geometric region sampled by our radio observations.

  4. 21-cm signature of the first sources in the Universe: prospects of detection with SKA

    NASA Astrophysics Data System (ADS)

    Ghara, Raghunath; Choudhury, T. Roy; Datta, Kanan K.

    2016-07-01

    Currently several low-frequency experiments are being planned to study the nature of the first stars using the redshifted 21-cm signal from the cosmic dawn and Epoch of Reionization. Using a one-dimensional radiative transfer code, we model the 21-cm signal pattern around the early sources for different source models, i.e. the metal-free Population III (PopIII) stars, primordial galaxies consisting of Population II (PopII) stars, mini-QSOs and high-mass X-ray binaries (HMXBs). We investigate the detectability of these sources by comparing the 21-cm visibility signal with the system noise appropriate for a telescope like the SKA1-low. Upon integrating the visibility around a typical source over all baselines and over a frequency interval of 16 MHz, we find that it will be possible to make a ˜9σ detection of the isolated sources like PopII galaxies, mini-QSOs and HMXBs at z ˜ 15 with the SKA1-low in 1000 h. The exact value of the signal-to-noise ratio (SNR) will depend on the source properties, in particular on the mass and age of the source and the escape fraction of ionizing photons. The predicted SNR decreases with increasing redshift. We provide simple scaling laws to estimate the SNR for different values of the parameters which characterize the source and the surrounding medium. We also argue that it will be possible to achieve an SNR ˜9 even in the presence of the astrophysical foregrounds by subtracting out the frequency-independent component of the observed signal. These calculations will be useful in planning 21-cm observations to detect the first sources.

  5. On the Detection of Global 21-cm Signal from Reionization Using Interferometers

    NASA Astrophysics Data System (ADS)

    Singh, Saurabh; Subrahmanyan, Ravi; Udaya Shankar, N.; Raghunathan, A.

    2015-12-01

    Detection of the global redshifted 21-cm signal is an excellent means of deciphering the physical processes during the Dark Ages and subsequent Epoch of Reionization (EoR). However, detection of this faint monopole is challenging due to the high precision required in instrumental calibration and modeling of substantially brighter foregrounds and instrumental systematics. In particular, modeling of receiver noise with mK accuracy and its separation remains a formidable task in experiments aiming to detect the global signal using single-element spectral radiometers. Interferometers do not respond to receiver noise; therefore, here we explore the theory of the response of interferometers to global signals. In other words, we discuss the spatial coherence in the electric field arising from the monopole component of the 21-cm signal and methods for its detection using sensor arrays. We proceed by first deriving the response to uniform sky of two-element interferometers made of unit dipole and resonant loop antennas, then extend the analysis to interferometers made of one-dimensional arrays and also consider two-dimensional aperture antennas. Finally, we describe methods by which the coherence might be enhanced so that the interferometer measurements yield improved sensitivity to the monopole component. We conclude (a) that it is indeed possible to measure the global 21-cm from EoR using interferometers, (b) that a practically useful configuration is with omnidirectional antennas as interferometer elements, and (c) that the spatial coherence may be enhanced using, for example, a space beam splitter between the interferometer elements.

  6. Cosmic 21 cm delensing of microwave background polarization and the minimum detectable energy scale of inflation.

    PubMed

    Sigurdson, Kris; Cooray, Asantha

    2005-11-18

    We propose a new method for removing gravitational lensing from maps of cosmic microwave background (CMB) polarization anisotropies. Using observations of anisotropies or structures in the cosmic 21 cm radiation, emitted or absorbed by neutral hydrogen atoms at redshifts 10 to 200, the CMB can be delensed. We find this method could allow CMB experiments to have increased sensitivity to a background of inflationary gravitational waves (IGWs) compared to methods relying on the CMB alone and may constrain models of inflation which were heretofore considered to have undetectable IGW amplitudes.

  7. GIANT METREWAVE RADIO TELESCOPE DETECTION OF TWO NEW H I 21 cm ABSORBERS AT z ≈ 2

    SciTech Connect

    Kanekar, N.

    2014-12-20

    I report the detection of H I 21 cm absorption in two high column density damped Lyα absorbers (DLAs) at z ≈ 2 using new wide-band 250-500 MHz receivers on board the Giant Metrewave Radio Telescope. The integrated H I 21 cm optical depths are 0.85 ± 0.16 km s{sup –1} (TXS1755+578) and 2.95 ± 0.15 km s{sup –1} (TXS1850+402). For the z = 1.9698 DLA toward TXS1755+578, the difference in H I 21 cm and C I profiles and the weakness of the radio core suggest that the H I 21cm absorption arises toward radio components in the jet, and that the optical and radio sightlines are not the same. This precludes an estimate of the DLA spin temperature. For the z = 1.9888 DLA toward TXS1850+402, the absorber covering factor is likely to be close to unity, as the background source is extremely compact, with the entire 5 GHz emission arising from a region of ≤ 1.4 mas in size. This yields a DLA spin temperature of T{sub s} = (372 ± 18) × (f/1.0) K, lower than typical T{sub s} values in high-z DLAs. This low spin temperature and the relatively high metallicity of the z = 1.9888 DLA ([Zn/H] =(– 0.68 ± 0.04)) are consistent with the anti-correlation between metallicity and spin temperature that has been found earlier in damped Lyα systems.

  8. The impact of anisotropy from finite light traveltime on detecting ionized bubbles in redshifted 21-cm maps

    NASA Astrophysics Data System (ADS)

    Majumdar, Suman; Bharadwaj, Somnath; Datta, Kanan K.; Choudhury, T. Roy

    2011-05-01

    The detection of ionized bubbles around quasars in redshifted 21-cm maps is possibly one of the most direct future probes of reionization. We consider two models for the growth of spherical ionized bubbles to study the apparent shapes of the bubbles in redshifted 21-cm maps, taking into account the finite light traveltime (FLTT) across the bubble. In both models, the bubble has a period of rapid growth beyond which its radius either saturates or grows slowly. We find that the FLTT, whose effect is particularly pronounced for large bubbles, causes the bubble’s image to continue to grow well after its actual growth is over. There are two distinct FLTT distortions in the bubble’s image: (i) its apparent centre is shifted along the line of sight (LOS) towards the observer from the quasar and (ii) it is anisotropic along the LOS. The bubble initially appears elongated along the LOS. This is reversed in the later stages of growth where the bubble appears compressed. The FLTT distortions are expected to have an impact on matched filter bubble detection where it is most convenient to use a spherical template for the filter. We find that the best matched spherical filter gives a reasonably good estimate of the size and the shift in the centre of the anisotropic image. The mismatch between the spherical filter and the anisotropic image causes a degradation in the signal-to-noise ratio relative to that of a spherical bubble. The degradation is in the range 10-20 per cent during the period of rapid growth when the image appears elongated and is less than 10 per cent in the later stages when the image appears compressed. We conclude that a spherical filter is adequate for bubble detection. The FLTT distortions do not affect the lower limits for bubble detection with 1000 h of GMRT observations. The smallest spherical filter for which a detection is possible has comoving radii 24 and 33 Mpc for 3σ and 5σ detections, respectively, assuming a neutral fraction 0.6 at z˜ 8.

  9. Simulating the 21 cm forest detectable with LOFAR and SKA in the spectra of high-z GRBs

    NASA Astrophysics Data System (ADS)

    Ciardi, B.; Inoue, S.; Abdalla, F. B.; Asad, K.; Bernardi, G.; Bolton, J. S.; Brentjens, M.; de Bruyn, A. G.; Chapman, E.; Daiboo, S.; Fernandez, E. R.; Ghosh, A.; Graziani, L.; Harker, G. J. A.; Iliev, I. T.; Jelić, V.; Jensen, H.; Kazemi, S.; Koopmans, L. V. E.; Martinez, O.; Maselli, A.; Mellema, G.; Offringa, A. R.; Pandey, V. N.; Schaye, J.; Thomas, R.; Vedantham, H.; Yatawatta, S.; Zaroubi, S.

    2015-10-01

    We investigate the feasibility of detecting 21 cm absorption features in the afterglow spectra of high redshift long Gamma Ray Bursts (GRBs). This is done employing simulations of cosmic reionization, together with estimates of the GRB radio afterglow flux and the instrumental characteristics of the LOw Frequency ARray (LOFAR). We find that absorption features could be marginally (with a S/N larger than a few) detected by LOFAR at z ≳ 7 if the GRB is a highly energetic event originating from Pop III stars, while the detection would be easier if the noise were reduced by one order of magnitude, i.e. similar to what is expected for the first phase of the Square Kilometre Array (SKA1-low). On the other hand, more standard GRBs are too dim to be detected even with ten times the sensitivity of SKA1-low, and only in the most optimistic case can a S/N larger than a few be reached at z ≳ 9.

  10. The Effects of the Ionosphere on Ground-based Detection of the Global 21 cm Signal from the Cosmic Dawn and the Dark Ages

    NASA Astrophysics Data System (ADS)

    Datta, Abhirup; Bradley, Richard; Burns, Jack O.; Harker, Geraint; Komjathy, Attila; Lazio, T. Joseph W.

    2016-11-01

    Detection of the global H i 21 cm signal from the Cosmic Dawn and the Epoch of Reionization is the key science driver for several ongoing ground-based and future ground-/space-based experiments. The crucial spectral features in the global 21 cm signal (turning points) occur at low radio frequencies ≲ 100 {{MHz}}. In addition to the human-generated radio frequency interference, Earth’s ionosphere drastically corrupts low-frequency radio observations from the ground. In this paper, we examine the effects of time-varying ionospheric refraction, absorption, and thermal emission at these low radio frequencies and their combined effect on any ground-based global 21 cm experiment. It should be noted that this is the first study of the effect of a dynamic ionosphere on global 21 cm experiments. The fluctuations in the ionosphere are influenced by solar activity with flicker noise characteristics. The same characteristics are reflected in the ionospheric corruption to any radio signal passing through the ionosphere. As a result, any ground-based observations of the faint global 21 cm signal are corrupted by flicker noise (or 1/f noise, where f is the dynamical frequency) which scales as {ν }-2 (where ν is the frequency of radio observation) in the presence of a bright galactic foreground (\\propto {ν }-s, where s is the radio spectral index). Hence, the calibration of the ionosphere for any such experiment is critical. Any attempt to calibrate the ionospheric effects will be subject to the inaccuracies in the current ionospheric measurements using Global Positioning System (GPS) ionospheric measurements, riometer measurements, ionospheric soundings, etc. Even considering an optimistic improvement in the accuracy of GPS–total electron content measurements, we conclude that Earth’s ionosphere poses a significant challenge in the absolute detection of the global 21 cm signal below 100 MHz.

  11. Interpreting Sky-Averaged 21-cm Measurements

    NASA Astrophysics Data System (ADS)

    Mirocha, Jordan

    2015-01-01

    Within the first ~billion years after the Big Bang, the intergalactic medium (IGM) underwent a remarkable transformation, from a uniform sea of cold neutral hydrogen gas to a fully ionized, metal-enriched plasma. Three milestones during this epoch of reionization -- the emergence of the first stars, black holes (BHs), and full-fledged galaxies -- are expected to manifest themselves as extrema in sky-averaged ("global") measurements of the redshifted 21-cm background. However, interpreting these measurements will be complicated by the presence of strong foregrounds and non-trivialities in the radiative transfer (RT) modeling required to make robust predictions.I have developed numerical models that efficiently solve the frequency-dependent radiative transfer equation, which has led to two advances in studies of the global 21-cm signal. First, frequency-dependent solutions facilitate studies of how the global 21-cm signal may be used to constrain the detailed spectral properties of the first stars, BHs, and galaxies, rather than just the timing of their formation. And second, the speed of these calculations allows one to search vast expanses of a currently unconstrained parameter space, while simultaneously characterizing the degeneracies between parameters of interest. I find principally that (1) physical properties of the IGM, such as its temperature and ionization state, can be constrained robustly from observations of the global 21-cm signal without invoking models for the astrophysical sources themselves, (2) translating IGM properties to galaxy properties is challenging, in large part due to frequency-dependent effects. For instance, evolution in the characteristic spectrum of accreting BHs can modify the 21-cm absorption signal at levels accessible to first generation instruments, but could easily be confused with evolution in the X-ray luminosity star-formation rate relation. Finally, (3) the independent constraints most likely to aide in the interpretation

  12. Calibration requirements for detecting the 21 cm epoch of reionization power spectrum and implications for the SKA

    NASA Astrophysics Data System (ADS)

    Barry, N.; Hazelton, B.; Sullivan, I.; Morales, M. F.; Pober, J. C.

    2016-09-01

    21 cm epoch of reionization (EoR) observations promise to transform our understanding of galaxy formation, but these observations are impossible without unprecedented levels of instrument calibration. We present end-to-end simulations of a full EoR power spectrum (PS) analysis including all of the major components of a real data processing pipeline: models of astrophysical foregrounds and EoR signal, frequency-dependent instrument effects, sky-based antenna calibration, and the full PS analysis. This study reveals that traditional sky-based per-frequency antenna calibration can only be implemented in EoR measurement analyses if the calibration model is unrealistically accurate. For reasonable levels of catalogue completeness, the calibration introduces contamination in otherwise foreground-free PS modes, precluding a PS measurement. We explore the origin of this contamination and potential mitigation techniques. We show that there is a strong joint constraint on the precision of the calibration catalogue and the inherent spectral smoothness of antennas, and that this has significant implications for the instrumental design of the SKA (Square Kilometre Array) and other future EoR observatories.

  13. Constraining dark matter through 21-cm observations

    NASA Astrophysics Data System (ADS)

    Valdés, M.; Ferrara, A.; Mapelli, M.; Ripamonti, E.

    2007-05-01

    Beyond reionization epoch cosmic hydrogen is neutral and can be directly observed through its 21-cm line signal. If dark matter (DM) decays or annihilates, the corresponding energy input affects the hydrogen kinetic temperature and ionized fraction, and contributes to the Lyα background. The changes induced by these processes on the 21-cm signal can then be used to constrain the proposed DM candidates, among which we select the three most popular ones: (i) 25-keV decaying sterile neutrinos, (ii) 10-MeV decaying light dark matter (LDM) and (iii) 10-MeV annihilating LDM. Although we find that the DM effects are considerably smaller than found by previous studies (due to a more physical description of the energy transfer from DM to the gas), we conclude that combined observations of the 21-cm background and of its gradient should be able to put constrains at least on LDM candidates. In fact, LDM decays (annihilations) induce differential brightness temperature variations with respect to the non-decaying/annihilating DM case up to ΔδTb = 8 (22) mK at about 50 (15) MHz. In principle, this signal could be detected both by current single-dish radio telescopes and future facilities as Low Frequency Array; however, this assumes that ionospheric, interference and foreground issues can be properly taken care of.

  14. A correlation between the H I 21-cm absorption strength and impact parameter in external galaxies

    NASA Astrophysics Data System (ADS)

    Curran, S. J.; Reeves, S. N.; Allison, J. R.; Sadler, E. M.

    2016-07-01

    By combining the data from surveys for H I 21-cm absorption at various impact parameters in near-by galaxies, we report an anti-correlation between the 21-cm absorption strength (velocity integrated optical depth) and the impact parameter. Also, by combining the 21-cm absorption strength with that of the emission, giving the neutral hydrogen column density, N_{H I}, we find no evidence that the spin temperature of the gas (degenerate with the covering factor) varies significantly across the disc. This is consistent with the uniformity of spin temperature measured across the Galactic disc. Furthermore, comparison with the Galactic N_{H I} distribution suggests that intervening 21-cm absorption preferentially arises in discs of high inclinations (near face-on). We also investigate the hypothesis that 21-cm absorption is favourably detected towards compact radio sources. Although there is insufficient data to determine whether there is a higher detection rate towards quasar, rather than radio galaxy, sight-lines, the 21-cm detections intervene objects with a mean turnover frequency of < ν _{_TO}rangle ≈ 5× 108 Hz, compared to < ν _{_TO}rangle ≈ 1× 108 Hz for the non-detections. Since the turnover frequency is anti-correlated with radio source size, this does indicate a preferential bias for detection towards compact background radio sources.

  15. Overcoming the Challenges of 21cm Cosmology

    NASA Astrophysics Data System (ADS)

    Pober, Jonathan

    just for PAPER, but for nearly all of a large class of new wide-field, drift- scanning radio telescopes: primary beam calibration in the presence of a poorly measured sky. Since these telescopes lack the ability to steer their primary beams, while seeing nearly the entire sky at once, a large number of calibrator sources are necessary to probe the entire beam response. However, the catalogs of radio sources at low-frequencies are not reliable enough to achieve the level of primary beam accuraccy needed for 21cm cosmology experiments. I develop, test, and apply a new technique which -- using only the assumption of symmetry around a 180° rotation -- simultaneously solves for the primary beam and the flux density of large number of sources. In this dissertation, I also present the analysis of new observations from PAPER to test theoretical models which predict foreground emission is confined to a "wedge"-like region of cosmological Fourier space, leaving an "EoR window" free from contamination. For the first time in actual observations, these predictions are spectacularly confirmed. In many ways, this result shifts the burden for upcoming PAPER analysis from foreground removal to increased sensitivity. And although increasing sensitivity is no small feat in-and-of-itself, this result is highly encouraging for 21cm studies, as foreground removal was long-viewed as the principal challenge for this field. The final result in this dissertation is the application of the all the lessons learned building PAPER and the MWA to design a new experiment for 21cm studies at z ˜ 1 with the goal of measuring baryon acoustic oscillations (BAO). The design of the BAO Broadband and Broad-beam (BAOBAB) Array is described, and cosmological forecasts are presented. The bottom line is highly encouraging, suggesting that z ˜ 1 21cm observations can detect the neutral hydrogen power spectrum with a very modest (16 - 32 element) array, and that still reasonably sized (128 - 256 elements

  16. Probing lepton asymmetry with 21 cm fluctuations

    SciTech Connect

    Kohri, Kazunori; Oyama, Yoshihiko; Sekiguchi, Toyokazu; Takahashi, Tomo E-mail: oyamayo@post.kek.jp E-mail: tomot@cc.saga-u.ac.jp

    2014-09-01

    We investigate the issue of how accurately we can constrain the lepton number asymmetry ξ{sub ν}=μ{sub ν}/T{sub ν} in the Universe by using future observations of 21 cm line fluctuations and cosmic microwave background (CMB). We find that combinations of the 21 cm line and the CMB observations can constrain the lepton asymmetry better than big-bang nucleosynthesis (BBN). Additionally, we also discuss constraints on ξ{sub ν} in the presence of some extra radiation, and show that the 21 cm line observations can substantially improve the constraints obtained by CMB alone, and allow us to distinguish the effects of the lepton asymmetry from the ones of extra radiation.

  17. The 21 cm signature of a cosmic string loop

    SciTech Connect

    Pagano, Michael; Brandenberger, Robert E-mail: rhb@physics.mcgill.ca

    2012-05-01

    Cosmic string loops lead to nonlinear baryon overdensities at early times, even before the time which in the standard LCDM model corresponds to the time of reionization. These overdense structures lead to signals in 21 cm redshift surveys at large redshifts. In this paper, we calculate the amplitude and shape of the string loop-induced 21 cm brightness temperature. We find that a string loop leads to a roughly elliptical region in redshift space with extra 21 cm emission. The excess brightness temperature for strings with a tension close to the current upper bound can be as high as 1deg K for string loops generated at early cosmological times (times comparable to the time of equal matter and radiation) and observed at a redshift of z+1 = 30. The angular extent of these predicted 'bright spots' is x{sup '}. These signals should be detectable in upcoming high redshift 21 cm surveys. We also discuss the application of our results to global monopoles and primordial black holes.

  18. BRIGHT SOURCE SUBTRACTION REQUIREMENTS FOR REDSHIFTED 21 cm MEASUREMENTS

    SciTech Connect

    Datta, A.; Bowman, J. D.; Carilli, C. L.

    2010-11-20

    The H I 21 cm transition line is expected to be an important probe into the cosmic dark ages and epoch of reionization. Foreground source removal is one of the principal challenges for the detection of this signal. This paper investigates the extragalactic point source contamination and how accurately bright sources ({approx}>1 Jy) must be removed in order to detect 21 cm emission with upcoming radio telescopes such as the Murchison Widefield Array. We consider the residual contamination in 21 cm maps and power spectra due to position errors in the sky model for bright sources, as well as frequency-independent calibration errors. We find that a source position accuracy of 0.1 arcsec will suffice for detection of the H I power spectrum. For calibration errors, 0.05% accuracy in antenna gain amplitude is required in order to detect the cosmic signal. Both sources of subtraction error produce residuals that are localized to small angular scales, k{sub perpendicular} {approx}> 0.05 Mpc{sup -1}, in the two-dimensional power spectrum.

  19. Redundant Array Configurations for 21 cm Cosmology

    NASA Astrophysics Data System (ADS)

    Dillon, Joshua S.; Parsons, Aaron R.

    2016-08-01

    Realizing the potential of 21 cm tomography to statistically probe the intergalactic medium before and during the Epoch of Reionization requires large telescopes and precise control of systematics. Next-generation telescopes are now being designed and built to meet these challenges, drawing lessons from first-generation experiments that showed the benefits of densely packed, highly redundant arrays—in which the same mode on the sky is sampled by many antenna pairs—for achieving high sensitivity, precise calibration, and robust foreground mitigation. In this work, we focus on the Hydrogen Epoch of Reionization Array (HERA) as an interferometer with a dense, redundant core designed following these lessons to be optimized for 21 cm cosmology. We show how modestly supplementing or modifying a compact design like HERA’s can still deliver high sensitivity while enhancing strategies for calibration and foreground mitigation. In particular, we compare the imaging capability of several array configurations, both instantaneously (to address instrumental and ionospheric effects) and with rotation synthesis (for foreground removal). We also examine the effects that configuration has on calibratability using instantaneous redundancy. We find that improved imaging with sub-aperture sampling via “off-grid” antennas and increased angular resolution via far-flung “outrigger” antennas is possible with a redundantly calibratable array configuration.

  20. Combining galaxy and 21-cm surveys

    NASA Astrophysics Data System (ADS)

    Cohn, J. D.; White, Martin; Chang, Tzu-Ching; Holder, Gil; Padmanabhan, Nikhil; Doré, Olivier

    2016-04-01

    Acoustic waves travelling through the early Universe imprint a characteristic scale in the clustering of galaxies, QSOs and intergalactic gas. This scale can be used as a standard ruler to map the expansion history of the Universe, a technique known as baryon acoustic oscillations (BAO). BAO offer a high-precision, low-systematics means of constraining our cosmological model. The statistical power of BAO measurements can be improved if the `smearing' of the acoustic feature by non-linear structure formation is undone in a process known as reconstruction. In this paper, we use low-order Lagrangian perturbation theory to study the ability of 21-cm experiments to perform reconstruction and how augmenting these surveys with galaxy redshift surveys at relatively low number densities can improve performance. We find that the critical number density which must be achieved in order to benefit 21-cm surveys is set by the linear theory power spectrum near its peak, and corresponds to densities achievable by upcoming surveys of emission line galaxies such as eBOSS and DESI. As part of this work, we analyse reconstruction within the framework of Lagrangian perturbation theory with local Lagrangian bias, redshift-space distortions, {k}-dependent noise and anisotropic filtering schemes.

  1. Intensity Mapping During Reionization: 21 cm and Cross-correlations

    NASA Astrophysics Data System (ADS)

    Aguirre, James E.; HERA Collaboration

    2016-01-01

    The first generation of 21 cm epoch of reionization (EoR) experiments are now reaching the sensitivities necessary for a detection of the power spectrum of plausible reionization models, and with the advent of next-generation capabilities (e.g. the Hydrogen Epoch of Reionization Array (HERA) and the Square Kilometer Array Phase I Low) will move beyond the power spectrum to imaging of the EoR intergalactic medium. Such datasets provide context to galaxy evolution studies for the earliest galaxies on scales of tens of Mpc, but at present wide, deep galaxy surveys are lacking, and attaining the depth to survey the bulk of galaxies responsible for reionization will be challenging even for JWST. Thus we seek useful cross-correlations with other more direct tracers of the galaxy population. I review near-term prospects for cross-correlation studies with 21 cm and CO and CII emission, as well as future far-infrared misions suchas CALISTO.

  2. 21 Cm Tomography With the Alfalfa Survey

    NASA Astrophysics Data System (ADS)

    Fry, Alexander B.; Boutan, C.; Carroll, P. A.; Hazelton, B.; Morales, M. F.

    2011-01-01

    Neutral hydrogen (HI) 21cm intensity mapping, or HI tomography is a promising technique being utilized by several upcoming experiments (LOFAR, MWA, SKA). The measurement of volume averaged neutral hydrogen mass density in synoptic sky surveys can be applied to the study of the HI mass function, the distribution of large scale structure, the reionization of the universe, and the expansion history of the universe through such standard rulers as baryonic acoustic oscillations. In order to prepare for future experiments, in particular the Murchison Widefield Array (MWA), we analyze the Arecbo Legacy Fast ALFA (Arecibo L-Band Feed Array) Feed Array (ALFALFA) survey data to probe the spatial density variations of HI in our local universe (z <0.06) where data is currently available. We address challenges unique to data of this kind, such as identifying and subtracting out signal from RFI and local galactic sources, and characterizing the ALFA array beam pattern which dictates sensitivity and resolution.

  3. The future of primordial features with 21 cm tomography

    NASA Astrophysics Data System (ADS)

    Chen, Xingang; Meerburg, P. Daniel; Münchmeyer, Moritz

    2016-09-01

    Detecting a deviation from a featureless primordial power spectrum of fluctuations would give profound insight into the physics of the primordial Universe. Depending on their nature, primordial features can either provide direct evidence for the inflation scenario or pin down details of the inflation model. Thus far, using the cosmic microwave background (CMB) we have only been able to put stringent constraints on the amplitude of features, but no significant evidence has been found for such signals. Here we explore the limit of the experimental reach in constraining such features using 21 cm tomography at high redshift. A measurement of the 21 cm power spectrum from the Dark Ages is generally considered as the ideal experiment for early Universe physics, with potentially access to a large number of modes. We consider three different categories of theoretically motivated models: the sharp feature models, resonance models, and standard clock models. We study the improvements on bounds on features as a function of the total number of observed modes and identify parameter degeneracies. The detectability depends critically on the amplitude, frequency and scale-location of the features, as well as the angular and redshift resolution of the experiment. We quantify these effects by considering different fiducial models. Our forecast shows that a cosmic variance limited 21 cm experiment measuring fluctuations in the redshift range 30 <= z <= 100 with a 0.01-MHz bandwidth and sub-arcminute angular resolution could potentially improve bounds by several orders of magnitude for most features compared to current Planck bounds. At the same time, 21 cm tomography also opens up a unique window into features that are located on very small scales.

  4. High redshift signatures in the 21 cm forest due to cosmic string wakes

    SciTech Connect

    Tashiro, Hiroyuki; Sekiguchi, Toyokazu; Silk, Joseph E-mail: toyokazu.sekiguchi@nagoya-u.jp

    2014-01-01

    Cosmic strings induce minihalo formation in the early universe. The resultant minihalos cluster in string wakes and create a ''21 cm forest'' against the cosmic microwave background (CMB) spectrum. Such a 21 cm forest can contribute to angular fluctuations of redshifted 21 cm signals integrated along the line of sight. We calculate the root-mean-square amplitude of the 21 cm fluctuations due to strings and show that these fluctuations can dominate signals from minihalos due to primordial density fluctuations at high redshift (z∼>10), even if the string tension is below the current upper bound, Gμ < 1.5 × 10{sup −7}. Our results also predict that the Square Kilometre Array (SKA) can potentially detect the 21 cm fluctuations due to strings with Gμ ≈ 7.5 × 10{sup −8} for the single frequency band case and 4.0 × 10{sup −8} for the multi-frequency band case.

  5. High redshift signatures in the 21 cm forest due to cosmic string wakes

    NASA Astrophysics Data System (ADS)

    Tashiro, Hiroyuki; Sekiguchi, Toyokazu; Silk, Joseph

    2014-01-01

    Cosmic strings induce minihalo formation in the early universe. The resultant minihalos cluster in string wakes and create a ``21 cm forest'' against the cosmic microwave background (CMB) spectrum. Such a 21 cm forest can contribute to angular fluctuations of redshifted 21 cm signals integrated along the line of sight. We calculate the root-mean-square amplitude of the 21 cm fluctuations due to strings and show that these fluctuations can dominate signals from minihalos due to primordial density fluctuations at high redshift (zgtrsim10), even if the string tension is below the current upper bound, Gμ < 1.5 × 10-7. Our results also predict that the Square Kilometre Array (SKA) can potentially detect the 21 cm fluctuations due to strings with Gμ ≈ 7.5 × 10-8 for the single frequency band case and 4.0 × 10-8 for the multi-frequency band case.

  6. Measuring the Cosmological 21 cm Monopole with an Interferometer

    NASA Astrophysics Data System (ADS)

    Presley, Morgan E.; Liu, Adrian; Parsons, Aaron R.

    2015-08-01

    A measurement of the cosmological 21 {cm} signal remains a promising but as-of-yet unattained ambition of radio astronomy. A positive detection would provide direct observations of key unexplored epochs of our cosmic history, including the cosmic dark ages and reionization. In this paper, we concentrate on measurements of the spatial monopole of the 21 {cm} brightness temperature as a function of redshift (the “global signal”). Most global experiments to date have been single-element experiments. In this paper, we show how an interferometer can be designed to be sensitive to the monopole mode of the sky, thus providing an alternate approach to accessing the global signature. We provide simple rules of thumb for designing a global signal interferometer and use numerical simulations to show that a modest array of tightly packed antenna elements with moderately sized primary beams (FWHM of ∼ 40^\\circ ) can compete with typical single-element experiments in their ability to constrain phenomenological parameters pertaining to reionization and the pre-reionization era. We also provide a general data analysis framework for extracting the global signal from interferometric measurements (with analysis of single-element experiments arising as a special case) and discuss trade-offs with various data analysis choices. Given that interferometric measurements are able to avoid a number of systematics inherent in single-element experiments, our results suggest that interferometry ought to be explored as a complementary way to probe the global signal.

  7. An intensity map of hydrogen 21-cm emission at redshift z approximately 0.8.

    PubMed

    Chang, Tzu-Ching; Pen, Ue-Li; Bandura, Kevin; Peterson, Jeffrey B

    2010-07-22

    Observations of 21-cm radio emission by neutral hydrogen at redshifts z approximately 0.5 to approximately 2.5 are expected to provide a sensitive probe of cosmic dark energy. This is particularly true around the onset of acceleration at z approximately 1, where traditional optical cosmology becomes very difficult because of the infrared opacity of the atmosphere. Hitherto, 21-cm emission has been detected only to z = 0.24. More distant galaxies generally are too faint for individual detections but it is possible to measure the aggregate emission from many unresolved galaxies in the 'cosmic web'. Here we report a three-dimensional 21-cm intensity field at z = 0.53 to 1.12. We then co-add neutral-hydrogen (H i) emission from the volumes surrounding about 10,000 galaxies (from the DEEP2 optical galaxy redshift survey). We detect the aggregate 21-cm glow at a significance of approximately 4sigma.

  8. The Murchison Widefield Array 21 cm Power Spectrum Analysis Methodology

    NASA Astrophysics Data System (ADS)

    Jacobs, Daniel C.; Hazelton, B. J.; Trott, C. M.; Dillon, Joshua S.; Pindor, B.; Sullivan, I. S.; Pober, J. C.; Barry, N.; Beardsley, A. P.; Bernardi, G.; Bowman, Judd D.; Briggs, F.; Cappallo, R. J.; Carroll, P.; Corey, B. E.; de Oliveira-Costa, A.; Emrich, D.; Ewall-Wice, A.; Feng, L.; Gaensler, B. M.; Goeke, R.; Greenhill, L. J.; Hewitt, J. N.; Hurley-Walker, N.; Johnston-Hollitt, M.; Kaplan, D. L.; Kasper, J. C.; Kim, HS; Kratzenberg, E.; Lenc, E.; Line, J.; Loeb, A.; Lonsdale, C. J.; Lynch, M. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Neben, A. R.; Thyagarajan, N.; Oberoi, D.; Offringa, A. R.; Ord, S. M.; Paul, S.; Prabu, T.; Procopio, P.; Riding, J.; Rogers, A. E. E.; Roshi, A.; Udaya Shankar, N.; Sethi, Shiv K.; Srivani, K. S.; Subrahmanyan, R.; Tegmark, M.; Tingay, S. J.; Waterson, M.; Wayth, R. B.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.; Wu, C.; Wyithe, J. S. B.

    2016-07-01

    We present the 21 cm power spectrum analysis approach of the Murchison Widefield Array Epoch of Reionization project. In this paper, we compare the outputs of multiple pipelines for the purpose of validating statistical limits cosmological hydrogen at redshifts between 6 and 12. Multiple independent data calibration and reduction pipelines are used to make power spectrum limits on a fiducial night of data. Comparing the outputs of imaging and power spectrum stages highlights differences in calibration, foreground subtraction, and power spectrum calculation. The power spectra found using these different methods span a space defined by the various tradeoffs between speed, accuracy, and systematic control. Lessons learned from comparing the pipelines range from the algorithmic to the prosaically mundane; all demonstrate the many pitfalls of neglecting reproducibility. We briefly discuss the way these different methods attempt to handle the question of evaluating a significant detection in the presence of foregrounds.

  9. Measuring the X-ray background in the reionization era with first generation 21 cm experiments

    SciTech Connect

    Christian, Pierre; Loeb, Abraham E-mail: aloeb@cfa.harvard.edu

    2013-09-01

    The X-ray background during the epoch of reionization is currently poorly constrained. We demonstrate that it is possible to use first generation 21 cm experiments to calibrate it. Using the semi-numerical simulation, 21cmFAST, we calculate the dependence of the 21 cm power spectrum on the X-ray background flux. Comparing the signal to the sensitivity of the Murchison Widefield Array (MWA) we find that in the redshift interval z =8-14 the 21 cm signal is detectable for certain values of the X-ray background. We show that there is no degeneracy between the X-ray production efficiency and the Lyα production efficiency and that the degeneracy with the ionization fraction of the intergalactic medium can be broken.

  10. Cross-correlation of the cosmic 21-cm signal and Lyman α emitters during reionization

    NASA Astrophysics Data System (ADS)

    Sobacchi, Emanuele; Mesinger, Andrei; Greig, Bradley

    2016-07-01

    Interferometry of the cosmic 21-cm signal is set to revolutionize our understanding of the Epoch of Reionization (EoR), eventually providing 3D maps of the early Universe. Initial detections however will be low signal to noise, limited by systematics. To confirm a putative 21-cm detection, and check the accuracy of 21-cm data analysis pipelines, it would be very useful to cross-correlate against a genuine cosmological signal. The most promising cosmological signals are wide-field maps of Lyman α emitting galaxies (LAEs), expected from the Subaru Hyper-Suprime Cam ultradeep field (UDF). Here we present estimates of the correlation between LAE maps at z ˜ 7 and the 21-cm signal observed by both the Low Frequency Array (LOFAR) and the planned Square Kilometre Array Phase 1 (SKA1). We adopt a systematic approach, varying both: (i) the prescription of assigning LAEs to host haloes; and (ii) the large-scale structure of neutral and ionized regions (i.e. EoR morphology). We find that the LAE-21cm cross-correlation is insensitive to (i), thus making it a robust probe of the EoR. A 1000 h observation with LOFAR would be sufficient to discriminate at ≳ 1σ a fully ionized Universe from one with a mean neutral fraction of bar{x}_{H I}≈ 0.50, using the LAE-21 cm cross-correlation function on scales of R ≈ 3-10 Mpc. Unlike LOFAR, whose detection of the LAE-21 cm cross-correlation is limited by noise, SKA1 is mostly limited by ignorance of the EoR morphology. However, the planned 100 h wide-field SKA1-Low survey will be sufficient to discriminate an ionized Universe from one with bar{x}_{H I}=0.25, even with maximally pessimistic assumptions.

  11. DEEP 21 cm H I OBSERVATIONS AT z {approx} 0.1: THE PRECURSOR TO THE ARECIBO ULTRA DEEP SURVEY

    SciTech Connect

    Freudling, Wolfram; Zwaan, Martin; Staveley-Smith, Lister; Meyer, Martin; Catinella, Barbara; Minchin, Robert; Calabretta, Mark; Momjian, Emmanuel; O'Neil, Karen

    2011-01-20

    The 'ALFA Ultra Deep Survey' (AUDS) is an ongoing 21 cm spectral survey with the Arecibo 305 m telescope. AUDS will be the most sensitive blind survey undertaken with Arecibo's 300 MHz Mock spectrometer. The survey searches for 21 cm H I line emission at redshifts between 0 and 0.16. The main goals of the survey are to investigate the H I content and probe the evolution of H I gas within that redshift region. In this paper, we report on a set of precursor observations with a total integration time of 53 hr. The survey detected a total of eighteen 21 cm emission lines at redshifts between 0.07 and 0.15 in a region centered around {alpha}{sub 2000} {approx} 0{sup h}, {delta} {approx} 15{sup 0}42'. The rate of detection is consistent with the one expected from the local H I mass function. The derived relative H I density at the median redshift of the survey is {rho}{sub H{sub I}}[z = 0.125] = (1.0 {+-} 0.3){rho}{sub 0}, where {rho}{sub 0} is the H I density at zero redshift.

  12. Unveiling the nature of dark matter with high redshift 21 cm line experiments

    SciTech Connect

    Evoli, C.; Mesinger, A.; Ferrara, A. E-mail: andrei.mesinger@sns.it

    2014-11-01

    Observations of the redshifted 21 cm line from neutral hydrogen will open a new window on the early Universe. By influencing the thermal and ionization history of the intergalactic medium (IGM), annihilating dark matter (DM) can leave a detectable imprint in the 21 cm signal. Building on the publicly available 21cmFAST code, we compute the 21 cm signal for a 10 GeV WIMP DM candidate. The most pronounced role of DM annihilations is in heating the IGM earlier and more uniformly than astrophysical sources of X-rays. This leaves several unambiguous, qualitative signatures in the redshift evolution of the large-scale (k ≅ 0.1 Mpc{sup -1}) 21 cm power amplitude: (i) the local maximum (peak) associated with IGM heating can be lower than the other maxima; (ii) the heating peak can occur while the IGM is in emission against the cosmic microwave background (CMB); (iii) there can be a dramatic drop in power (a global minimum) corresponding to the epoch when the IGM temperature is comparable to the CMB temperature. These signatures are robust to astrophysical uncertainties, and will be easily detectable with second generation interferometers. We also briefly show that decaying warm dark matter has a negligible role in heating the IGM.

  13. Precise measurements of primordial power spectrum with 21 cm fluctuations

    SciTech Connect

    Kohri, Kazunori; Oyama, Yoshihiko; Sekiguchi, Toyokazu; Takahashi, Tomo E-mail: oyamayo@post.kek.jp E-mail: tomot@cc.saga-u.ac.jp

    2013-10-01

    We discuss the issue of how precisely we can measure the primordial power spectrum by using future observations of 21 cm fluctuations and cosmic microwave background (CMB). For this purpose, we investigate projected constraints on the quantities characterizing primordial power spectrum: the spectral index n{sub s}, its running α{sub s} and even its higher order running β{sub s}. We show that future 21 cm observations in combinations with CMB would accurately measure above mentioned observables of primordial power spectrum. We also discuss its implications to some explicit inflationary models.

  14. A comparison of neutral hydrogen 21 cm observations with UV and optical absorption-line measurements

    NASA Technical Reports Server (NTRS)

    Giovanelli, R.; York, D. G.; Shull, J. M.; Haynes, M. P.

    1978-01-01

    Several absorption components detected in visible or UV lines have been identified with emission features in new high-resolution, high signal-to-noise 21 cm observations. Stars for which direct overlap is obtained are HD 28497, lambda Ori, mu Col, HD 50896, rho Leo, HD 93521, and HD 219881. With the use of the inferred H I column densities from 21 cm profiles, rather than the integrated column densities obtained from L-alpha, more reliable densities can be derived from the existence of molecular hydrogen. Hence the cloud thicknesses are better determined; and 21 cm emission maps near these stars can be used to obtain dimensions on the plane of the sky. It is now feasible to derive detailed geometries for isolated clumps of gas which produce visual absorption features.

  15. MAPPING THE DYNAMICS OF COLD GAS AROUND SGR A* THROUGH 21 cm ABSORPTION

    SciTech Connect

    Christian, Pierre; Loeb, Abraham

    2015-11-20

    The presence of a circumnuclear stellar disk around Sgr A* and megamaser systems near other black holes indicates that dense neutral disks can be found in galactic nuclei. We show that depending on their inclination angle, optical depth, and spin temperature, these disks could be observed spectroscopically through 21 cm absorption. Related spectroscopic observations of Sgr A* can determine its HI disk parameters and the possible presence of gaps in the disk. Clumps of dense gas similar to the G2 could could also be detected in 21 cm absorption against Sgr A* radio emission.

  16. Galaxy-cluster masses via 21st-century measurements of lensing of 21-cm fluctuations

    NASA Astrophysics Data System (ADS)

    Kovetz, Ely D.; Kamionkowski, Marc

    2013-03-01

    We discuss the prospects to measure galaxy-cluster properties via weak lensing of 21-cm fluctuations from the dark ages and the epoch of reionization (EOR). We choose as a figure of merit the smallest cluster mass detectable through such measurements. We construct the minimum-variance quadratic estimator for the cluster mass based on lensing of 21-cm fluctuations at multiple redshifts. We discuss the tradeoff among frequency bandwidth, angular resolution, and the number of redshift shells available for a fixed noise level for the radio detectors. Observations of lensing of the 21-cm background from the dark ages will be capable of detecting M≳1012h-1M⊙ mass halos, but will require futuristic experiments to overcome the contaminating sources. Next-generation radio measurements of 21-cm fluctuations from the EOR will, however, have the sensitivity to detect galaxy clusters with halo masses M≳1013h-1M⊙, given enough observation time (for the relevant sky patch) and collecting area to maximize their resolution capabilities.

  17. An intensity map of hydrogen 21-cm emission at redshift z approximately 0.8.

    PubMed

    Chang, Tzu-Ching; Pen, Ue-Li; Bandura, Kevin; Peterson, Jeffrey B

    2010-07-22

    Observations of 21-cm radio emission by neutral hydrogen at redshifts z approximately 0.5 to approximately 2.5 are expected to provide a sensitive probe of cosmic dark energy. This is particularly true around the onset of acceleration at z approximately 1, where traditional optical cosmology becomes very difficult because of the infrared opacity of the atmosphere. Hitherto, 21-cm emission has been detected only to z = 0.24. More distant galaxies generally are too faint for individual detections but it is possible to measure the aggregate emission from many unresolved galaxies in the 'cosmic web'. Here we report a three-dimensional 21-cm intensity field at z = 0.53 to 1.12. We then co-add neutral-hydrogen (H i) emission from the volumes surrounding about 10,000 galaxies (from the DEEP2 optical galaxy redshift survey). We detect the aggregate 21-cm glow at a significance of approximately 4sigma. PMID:20651685

  18. The rise of the first stars: Supersonic streaming, radiative feedback, and 21-cm cosmology

    NASA Astrophysics Data System (ADS)

    Barkana, Rennan

    2016-07-01

    Understanding the formation and evolution of the first stars and galaxies represents one of the most exciting frontiers in astronomy. Since the universe was filled with hydrogen atoms at early times, the most promising method for observing the epoch of the first stars is to use the prominent 21-cm spectral line of hydrogen. Current observational efforts are focused on the cosmic reionization era, but observations of the pre-reionization cosmic dawn are also beginning and promise exciting discoveries. While observationally unexplored, theoretical studies predict a rich variety of observational signatures from the astrophysics of the early galaxies that formed during cosmic dawn. As the first stars formed, their radiation (plus that from stellar remnants) produced feedback that radically affected both the intergalactic medium and the character of newly-forming stars. Lyman- α radiation from stars generated a strong 21-cm absorption signal, observation of which is currently the only feasible method of detecting the dominant population of galaxies at redshifts as early as z ∼ 25. Another major player is cosmic heating; if due to soft X-rays, then it occurred fairly early (z ∼ 15) and produced the strongest pre-reionization signal, while if it is due to hard X-rays, as now seems more likely, then it occurred later and may have dramatically affected the 21-cm sky even during reionization. In terms of analysis, much focus has gone to studying the angle-averaged power spectrum of 21-cm fluctuations, a rich dataset that can be used to reconstruct the astrophysical information of greatest interest. This does not, however, diminish the importance of finding additional probes that are complementary or amenable to a more model-independent analysis. Examples include the global (sky-averaged) 21-cm spectrum, and the line-of-sight anisotropy of the 21-cm power spectrum. Another striking feature may result from a recently recognized effect of a supersonic relative velocity

  19. From Darkness to Light: Signatures of the Universe's First Galaxies in the Cosmic 21-cm Background

    NASA Astrophysics Data System (ADS)

    Mirocha, Jordan

    Within the first billion years after the Big Bang, the intergalactic medium (IGM) underwent a remarkable transformation, from a uniform sea of cold neutral hydrogen gas to a fully ionized, metal-enriched plasma. Three milestones during this Epoch of Reionization -- the emergence of the first stars, black holes, and full-fledged galaxies -- are expected to manifest as spectral "turning points" in the sky-averaged ("global") 21-cm background. However, interpreting these measurements will be complicated by the presence of strong foregrounds and non-trivialities in the radiative transfer (RT) required to model the signal. In this thesis, I make the first attempt to build the final piece of a global 21-cm data analysis pipeline: an inference tool capable of extracting the properties of the IGM and the Universe's first galaxies from the recovered signal. Such a framework is valuable even prior to a detection of the global 21-cm signal as it enables end-to-end simulations of 21-cm observations that can be used to optimize the design of upcoming instruments, their observing strategies, and their signal extraction algorithms. En route to a complete pipeline, I found that (1) robust limits on the physical properties of the IGM, such as its temperature and ionization state, can be derived analytically from the 21-cm turning points within two-zone models for the IGM, (2) improved constraints on the IGM properties can be obtained through simultaneous fitting of the global 21-cm signal and foregrounds, though biases can emerge depending on the parameterized form of the signal one adopts, (3) a simple four-parameter galaxy formation model can be constrained in only 100 hours of integration provided a stable instrumental response over a broad frequency range (~80 MHz), and (4) frequency-dependent RT solutions in physical models for the global 21-cm signal will be required to properly interpret the 21-cm absorption minimum, as the IGM thermal history is highly sensitive to the

  20. Invisible Active Galactic Nuclei. II. Radio Morphologies and Five New H i 21cm Absorption Line Detectors

    NASA Astrophysics Data System (ADS)

    Yan, Ting; Stocke, John T.; Darling, Jeremy; Momjian, Emmanuel; Sharma, Soniya; Kanekar, Nissim

    2016-03-01

    This is the second paper directed toward finding new highly redshifted atomic and molecular absorption lines at radio frequencies. To this end, we selected a sample of 80 candidates for obscured radio-loud active galactic nuclei (AGNs) and presented their basic optical/near-infrared (NIR) properties in Paper I. In this paper, we present both high-resolution radio continuum images for all of these sources and H i 21 cm absorption spectroscopy for a few selected sources in this sample. A-configuration 4.9 and 8.5 GHz Very Large Array continuum observations find that 52 sources are compact or have substantial compact components with size <0.″5 and flux densities >0.1 Jy at 4.9 GHz. The 36 most compact sources were then observed with the Very Long Baseline Array at 1.4 GHz. One definite and 10 candidate Compact Symmetric Objects (CSOs) are newly identified, which is a detection rate of CSOs ∼three times higher than the detection rate previously found in purely flux-limited samples. Based on possessing compact components with high flux densities, 60 of these sources are good candidates for absorption-line searches. Twenty-seven sources were observed for H i 21 cm absorption at their photometric or spectroscopic redshifts with only six detections (five definite and one tentative). However, five of these were from a small subset of six CSOs with pure galaxy optical/NIR spectra (i.e., any AGN emission is obscured) and for which accurate spectroscopic redshifts place the redshifted 21 cm line in a radio frequency intereference (RFI)-free spectral “window” (i.e., the percentage of H i 21 cm absorption-line detections could be as high as ∼90% in this sample). It is likely that the presence of ubiquitous RFI and the absence of accurate spectroscopic redshifts preclude H i detections in similar sources (only 1 detection out of the remaining 22 sources observed, 13 of which have only photometric redshifts); that is, H i absorption may well be present but is masked by

  1. Precision measurement of cosmic magnification from 21 cm emitting galaxies

    SciTech Connect

    Zhang, Pengjie; Pen, Ue-Li; /Canadian Inst. Theor. Astrophys.

    2005-04-01

    We show how precision lensing measurements can be obtained through the lensing magnification effect in high redshift 21cm emission from galaxies. Normally, cosmic magnification measurements have been seriously complicated by galaxy clustering. With precise redshifts obtained from 21cm emission line wavelength, one can correlate galaxies at different source planes, or exclude close pairs to eliminate such contaminations. We provide forecasts for future surveys, specifically the SKA and CLAR. SKA can achieve percent precision on the dark matter power spectrum and the galaxy dark matter cross correlation power spectrum, while CLAR can measure an accurate cross correlation power spectrum. The neutral hydrogen fraction was most likely significantly higher at high redshifts, which improves the number of observed galaxies significantly, such that also CLAR can measure the dark matter lensing power spectrum. SKA can also allow precise measurement of lensing bispectrum.

  2. Lensing of 21-cm fluctuations by primordial gravitational waves.

    PubMed

    Book, Laura; Kamionkowski, Marc; Schmidt, Fabian

    2012-05-25

    Weak-gravitational-lensing distortions to the intensity pattern of 21-cm radiation from the dark ages can be decomposed geometrically into curl and curl-free components. Lensing by primordial gravitational waves induces a curl component, while the contribution from lensing by density fluctuations is strongly suppressed. Angular fluctuations in the 21-cm background extend to very small angular scales, and measurements at different frequencies probe different shells in redshift space. There is thus a huge trove of information with which to reconstruct the curl component of the lensing field, allowing tensor-to-scalar ratios conceivably as small as r~10(-9)-far smaller than those currently accessible-to be probed. PMID:23003237

  3. The 21 cm signature of cosmic string wakes

    SciTech Connect

    Brandenberger, Robert H.; Danos, Rebecca J.; Hernández, Oscar F.; Holder, Gilbert P. E-mail: rjdanos@physics.mcgill.ca E-mail: holder@physics.mcgill.ca

    2010-12-01

    We discuss the signature of a cosmic string wake in 21cm redshift surveys. Since 21cm surveys probe higher redshifts than optical large-scale structure surveys, the signatures of cosmic strings are more manifest in 21cm maps than they are in optical galaxy surveys. We find that, provided the tension of the cosmic string exceeds a critical value (which depends on both the redshift when the string wake is created and the redshift of observation), a cosmic string wake will generate an emission signal with a brightness temperature which approaches a limiting value which at a redshift of z+1 = 30 is close to 400 mK in the limit of large string tension. The signal will have a specific signature in position space: the excess 21cm radiation will be confined to a wedge-shaped region whose tip corresponds to the position of the string, whose planar dimensions are set by the planar dimensions of the string wake, and whose thickness (in redshift direction) depends on the string tension. For wakes created at z{sub i}+1 = 10{sup 3}, then at a redshift of z+1 = 30 the critical value of the string tension μ is Gμ = 6 × 10{sup −7}, and it decreases linearly with redshift (for wakes created at the time of equal matter and radiation, the critical value is a factor of two lower at the same redshift). For smaller tensions, cosmic strings lead to an observable absorption signal with the same wedge geometry.

  4. The wedge bias in reionization 21-cm power spectrum measurements

    NASA Astrophysics Data System (ADS)

    Jensen, Hannes; Majumdar, Suman; Mellema, Garrelt; Lidz, Adam; Iliev, Ilian T.; Dixon, Keri L.

    2016-02-01

    A proposed method for dealing with foreground emission in upcoming 21-cm observations from the epoch of reionization is to limit observations to an uncontaminated window in Fourier space. Foreground emission can be avoided in this way, since it is limited to a wedge-shaped region in k∥, k⊥ space. However, the power spectrum is anisotropic owing to redshift-space distortions from peculiar velocities. Consequently, the 21-cm power spectrum measured in the foreground avoidance window - which samples only a limited range of angles close to the line-of-sight direction - differs from the full redshift-space spherically averaged power spectrum which requires an average over all angles. In this paper, we calculate the magnitude of this `wedge bias' for the first time. We find that the bias amplifies the difference between the real-space and redshift-space power spectra. The bias is strongest at high redshifts, where measurements using foreground avoidance will overestimate the redshift-space power spectrum by around 100 per cent, possibly obscuring the distinctive rise and fall signature that is anticipated for the spherically averaged 21-cm power spectrum. In the later stages of reionization, the bias becomes negative, and smaller in magnitude (≲20 per cent).

  5. Simulating the 21 cm signal from reionization including non-linear ionizations and inhomogeneous recombinations

    NASA Astrophysics Data System (ADS)

    Hassan, Sultan; Davé, Romeel; Finlator, Kristian; Santos, Mario G.

    2016-04-01

    We explore the impact of incorporating physically motivated ionization and recombination rates on the history and topology of cosmic reionization and the resulting 21 cm power spectrum, by incorporating inputs from small-volume hydrodynamic simulations into our semi-numerical code, SIMFAST21, that evolves reionization on large scales. We employ radiative hydrodynamic simulations to parametrize the ionization rate Rion and recombination rate Rrec as functions of halo mass, overdensity and redshift. We find that Rion scales superlinearly with halo mass ({R_ion}∝ M_h^{1.41}), in contrast to previous assumptions. Implementing these scalings into SIMFAST21, we tune our one free parameter, the escape fraction fesc, to simultaneously reproduce recent observations of the Thomson optical depth, ionizing emissivity and volume-averaged neutral fraction by the end of reionization. This yields f_esc=4^{+7}_{-2} per cent averaged over our 0.375 h-1 Mpc cells, independent of halo mass or redshift, increasing to 6 per cent if we also constrain to match the observed z = 7 star formation rate function. Introducing superlinear Rion increases the duration of reionization and boosts small-scale 21 cm power by two to three times at intermediate phases of reionization, while inhomogeneous recombinations reduce ionized bubble sizes and suppress large-scale 21 cm power by two to three times. Gas clumping on sub-cell scales has a minimal effect on the 21 cm power. Superlinear Rion also significantly increases the median halo mass scale for ionizing photon output to ˜ 1010 M⊙, making the majority of reionizing sources more accessible to next-generation facilities. These results highlight the importance of accurately treating ionizing sources and recombinations for modelling reionization and its 21 cm power spectrum.

  6. Bayesian constraints on the global 21-cm signal from the Cosmic Dawn

    NASA Astrophysics Data System (ADS)

    Bernardi, G.; Zwart, J. T. L.; Price, D.; Greenhill, L. J.; Mesinger, A.; Dowell, J.; Eftekhari, T.; Ellingson, S. W.; Kocz, J.; Schinzel, F.

    2016-09-01

    The birth of the first luminous sources and the ensuing epoch of reionization are best studied via the redshifted 21-cm emission line, the signature of the first two imprinting the last. In this work, we present a fully Bayesian method, HIBAYES, for extracting the faint, global (sky-averaged) 21-cm signal from the much brighter foreground emission. We show that a simplified (but plausible) Gaussian model of the 21-cm emission from the Cosmic Dawn epoch (15 ≲ z ≲ 30), parametrized by an amplitude A_{H I}, a frequency peak ν _{H I} and a width σ _{H I}, can be extracted even in the presence of a structured foreground frequency spectrum (parametrized as a seventh-order polynomial), provided sufficient signal-to-noise (400 h of observation with a single dipole). We apply our method to an early, 19-min-long observation from the Large aperture Experiment to detect the Dark Ages, constraining the 21-cm signal amplitude and width to be -890 < A_{H I} < 0 mK and σ _{H I} > 6.5 MHz (corresponding to Δz > 1.9 at redshift z ≃ 20) respectively at the 95-per cent confidence level in the range 13.2 < z < 27.4 (100 > ν > 50 MHz).

  7. INTERPRETING THE GLOBAL 21-cm SIGNAL FROM HIGH REDSHIFTS. II. PARAMETER ESTIMATION FOR MODELS OF GALAXY FORMATION

    SciTech Connect

    Mirocha, Jordan; Burns, Jack O.; Harker, Geraint J. A.

    2015-11-01

    Following our previous work, which related generic features in the sky-averaged (global) 21-cm signal to properties of the intergalactic medium, we now investigate the prospects for constraining a simple galaxy formation model with current and near-future experiments. Markov-Chain Monte Carlo fits to our synthetic data set, which includes a realistic galactic foreground, a plausible model for the signal, and noise consistent with 100 hr of integration by an ideal instrument, suggest that a simple four-parameter model that links the production rate of Lyα, Lyman-continuum, and X-ray photons to the growth rate of dark matter halos can be well-constrained (to ∼0.1 dex in each dimension) so long as all three spectral features expected to occur between 40 ≲ ν/MHz ≲ 120 are detected. Several important conclusions follow naturally from this basic numerical result, namely that measurements of the global 21-cm signal can in principle (i) identify the characteristic halo mass threshold for star formation at all redshifts z ≳ 15, (ii) extend z ≲ 4 upper limits on the normalization of the X-ray luminosity star formation rate (L{sub X}–SFR) relation out to z ∼ 20, and (iii) provide joint constraints on stellar spectra and the escape fraction of ionizing radiation at z ∼ 12. Though our approach is general, the importance of a broadband measurement renders our findings most relevant to the proposed Dark Ages Radio Explorer, which will have a clean view of the global 21-cm signal from ∼40 to 120 MHz from its vantage point above the radio-quiet, ionosphere-free lunar far-side.

  8. The 21 cm signal and the interplay between dark matter annihilations and astrophysical processes

    NASA Astrophysics Data System (ADS)

    Lopez-Honorez, Laura; Mena, Olga; Moliné, Ángeles; Palomares-Ruiz, Sergio; Vincent, Aaron C.

    2016-08-01

    Future dedicated radio interferometers, including HERA and SKA, are very promising tools that aim to study the epoch of reionization and beyond via measurements of the 21 cm signal from neutral hydrogen. Dark matter (DM) annihilations into charged particles change the thermal history of the Universe and, as a consequence, affect the 21 cm signal. Accurately predicting the effect of DM strongly relies on the modeling of annihilations inside halos. In this work, we use up-to-date computations of the energy deposition rates by the products from DM annihilations, a proper treatment of the contribution from DM annihilations in halos, as well as values of the annihilation cross section allowed by the most recent cosmological measurements from the Planck satellite. Given current uncertainties on the description of the astrophysical processes driving the epochs of reionization, X-ray heating and Lyman-α pumping, we find that disentangling DM signatures from purely astrophysical effects, related to early-time star formation processes or late-time galaxy X-ray emissions, will be a challenging task. We conclude that only annihilations of DM particles with masses of ~100 MeV, could leave an unambiguous imprint on the 21 cm signal and, in particular, on the 21 cm power spectrum. This is in contrast to previous, more optimistic results in the literature, which have claimed that strong signatures might also be present even for much higher DM masses. Additional measurements of the 21 cm signal at different cosmic epochs will be crucial in order to break the strong parameter degeneracies between DM annihilations and astrophysical effects and undoubtedly single out a DM imprint for masses different from ~100 MeV.

  9. Probing patchy reionization through τ-21 cm correlation statistics

    SciTech Connect

    Meerburg, P. Daniel; Spergel, David N.; Dvorkin, Cora E-mail: dns@astro.princeton.edu

    2013-12-20

    We consider the cross-correlation between free electrons and neutral hydrogen during the epoch of reionization (EoR). The free electrons are traced by the optical depth to reionization τ, while the neutral hydrogen can be observed through 21 cm photon emission. As expected, this correlation is sensitive to the detailed physics of reionization. Foremost, if reionization occurs through the merger of relatively large halos hosting an ionizing source, the free electrons and neutral hydrogen are anticorrelated for most of the reionization history. A positive contribution to the correlation can occur when the halos that can form an ionizing source are small. A measurement of this sign change in the cross-correlation could help disentangle the bias and the ionization history. We estimate the signal-to-noise ratio of the cross-correlation using the estimator for inhomogeneous reionization τ-hat {sub ℓm} proposed by Dvorkin and Smith. We find that with upcoming radio interferometers and cosmic microwave background (CMB) experiments, the cross-correlation is measurable going up to multipoles ℓ ∼ 1000. We also derive parameter constraints and conclude that, despite the foregrounds, the cross-correlation provides a complementary measurement of the EoR parameters to the 21 cm and CMB polarization autocorrelations expected to be observed in the coming decade.

  10. The Application of Continuous Wavelet Transform Based Foreground Subtraction Method in 21 cm Sky Surveys

    NASA Astrophysics Data System (ADS)

    Gu, Junhua; Xu, Haiguang; Wang, Jingying; An, Tao; Chen, Wen

    2013-08-01

    We propose a continuous wavelet transform based non-parametric foreground subtraction method for the detection of redshifted 21 cm signal from the epoch of reionization. This method works based on the assumption that the foreground spectra are smooth in frequency domain, while the 21 cm signal spectrum is full of saw-tooth-like structures, thus their characteristic scales are significantly different. We can distinguish them in the wavelet coefficient space easily and perform the foreground subtraction. Compared with the traditional spectral fitting based method, our method is more tolerant to complex foregrounds. Furthermore, we also find that when the instrument has uncorrected response error, our method can also work significantly better than the spectral fitting based method. Our method can obtain similar results with the Wp smoothing method, which is also a non-parametric method, but our method consumes much less computing time.

  11. THE EFFECTS OF POLARIZED FOREGROUNDS ON 21 cm EPOCH OF REIONIZATION POWER SPECTRUM MEASUREMENTS

    SciTech Connect

    Moore, David F.; Aguirre, James E.; Parsons, Aaron R.; Pober, Jonathan C.; Jacobs, Daniel C.

    2013-06-01

    Experiments aimed at detecting highly-redshifted 21 cm emission from the epoch of reionization (EoR) are plagued by the contamination of foreground emission. A potentially important source of contaminating foregrounds may be Faraday-rotated, polarized emission, which leaks into the estimate of the intrinsically unpolarized EoR signal. While these foregrounds' intrinsic polarization may not be problematic, the spectral structure introduced by the Faraday rotation could be. To better understand and characterize these effects, we present a simulation of the polarized sky between 120 and 180 MHz. We compute a single visibility, and estimate the three-dimensional power spectrum from that visibility using the delay spectrum approach presented in Parsons et al. Using the Donald C. Backer Precision Array to Probe the Epoch of Reionization as an example instrument, we show the expected leakage into the unpolarized power spectrum to be several orders of magnitude above the expected 21 cm EoR signal.

  12. Mapping Cosmic Structure Using 21-cm Hydrogen Signal at Green Bank Telescope

    NASA Astrophysics Data System (ADS)

    Voytek, Tabitha; GBT 21-cm Intensity Mapping Group

    2011-05-01

    We are using the Green Bank Telescope to make 21-cm intensity maps of cosmic structure in a 0.15 Gpc^3 box at redshift of z 1. The intensity mapping technique combines the flux from many galaxies in each pixel, allowing much greater mapping speed than the traditional redshift survey. Measurement is being made at z 1 to take advantage of a window in frequency around 700 MHz where terrestrial radio frequency interference (RFI) is currently at a minimum. This minimum is due to a reallocation of this frequency band from analog television to wide area wireless internet and public service usage. We will report progress of our attempt to detect autocorrelation of the 21-cm signal. The ultimate goal of this mapping is to use Baryon Acoustic Oscillations to provide more precise constraints to dark energy models.

  13. An H I 21-cm line survey of evolved stars

    NASA Astrophysics Data System (ADS)

    Gérard, E.; Le Bertre, T.; Libert, Y.

    2011-12-01

    The HI line at 21 cm is a tracer of circumstellar matter around AGB stars, and especially of the matter located at large distances (0.1-1 pc) from the central stars. It can give unique information on the kinematics and on the physical conditions in the outer parts of circumstellar shells and in the regions where stellar matter is injected into the interstellar medium. However this tracer has not been much used up to now, due to the difficulty of separating the genuine circumstellar emission from the interstellar one. With the Nançay Radiotelescope we are carrying out a survey of the HI emission in a large sample of evolved stars. We report on recent progresses of this long term programme, with emphasis on S-type stars.

  14. HIBAYES: Global 21-cm Bayesian Monte-Carlo Model Fitting

    NASA Astrophysics Data System (ADS)

    Zwart, Jonathan T. L.; Price, Daniel; Bernardi, Gianni

    2016-06-01

    HIBAYES implements fully-Bayesian extraction of the sky-averaged (global) 21-cm signal from the Cosmic Dawn and Epoch of Reionization in the presence of foreground emission. User-defined likelihood and prior functions are called by the sampler PyMultiNest (ascl:1606.005) in order to jointly explore the full (signal plus foreground) posterior probability distribution and evaluate the Bayesian evidence for a given model. Implemented models, for simulation and fitting, include gaussians (HI signal) and polynomials (foregrounds). Some simple plotting and analysis tools are supplied. The code can be extended to other models (physical or empirical), to incorporate data from other experiments, or to use alternative Monte-Carlo sampling engines as required.

  15. Cosmic (Super)String Constraints from 21 cm Radiation

    SciTech Connect

    Khatri, Rishi; Wandelt, Benjamin D.

    2008-03-07

    We calculate the contribution of cosmic strings arising from a phase transition in the early Universe, or cosmic superstrings arising from brane inflation, to the cosmic 21 cm power spectrum at redshifts z{>=}30. Future experiments can exploit this effect to constrain the cosmic string tension G{mu} and probe virtually the entire brane inflation model space allowed by current observations. Although current experiments with a collecting area of {approx}1 km{sup 2} will not provide any useful constraints, future experiments with a collecting area of 10{sup 4}-10{sup 6} km{sup 2} covering the cleanest 10% of the sky can, in principle, constrain cosmic strings with tension G{mu} > or approx. 10{sup -10}-10{sup -12} (superstring/phase transition mass scale >10{sup 13} GeV)

  16. Cosmic (Super)String Constraints from 21 cm Radiation.

    PubMed

    Khatri, Rishi; Wandelt, Benjamin D

    2008-03-01

    We calculate the contribution of cosmic strings arising from a phase transition in the early Universe, or cosmic superstrings arising from brane inflation, to the cosmic 21 cm power spectrum at redshifts z > or =30. Future experiments can exploit this effect to constrain the cosmic string tension G mu and probe virtually the entire brane inflation model space allowed by current observations. Although current experiments with a collecting area of approximately 1 km2 will not provide any useful constraints, future experiments with a collecting area of 10(4)-10(6) km2 covering the cleanest 10% of the sky can, in principle, constrain cosmic strings with tension G mu > or = 10(-10)-10(-12) (superstring/phase transition mass scale >10(13) GeV). PMID:18352691

  17. Cross-correlating 21cm intensity maps with Lyman Break Galaxies in the post-reionization era

    SciTech Connect

    Villaescusa-Navarro, Francisco; Viel, Matteo; Alonso, David; Datta, Kanan K.; Santos, Mário G. E-mail: viel@oats.inaf.it E-mail: kanan@ncra.tifr.res.in E-mail: mgrsantos@uwc.ac.za

    2015-03-01

    We investigate the cross-correlation between the spatial distribution of Lyman Break Galaxies (LBGs) and the 21cm intensity mapping signal at z∼[3–5]. At these redshifts, galactic feedback is supposed to only marginally affect the matter power spectrum, and the neutral hydrogen distribution is independently constrained by quasar spectra. Using a high resolution N-body simulation, populated with neutral hydrogen a posteriori, we forecast for the expected LBG-21cm cross-spectrum and its error for a 21cm field observed by the Square Kilometre Array (SKA1-LOW and SKA1-MID), combined with a spectroscopic LBG survey with the same volume. The cross power can be detected with a signal-to-noise ratio (SNR) up to ∼10 times higher (and down to ∼ 4 times smaller scales) than the 21cm auto-spectrum for this set-up, with the SNR depending only very weakly on redshift and the LBG population. We also show that while both the 21cm auto- and LBG-21cm cross-spectra can be reliably recovered after the cleaning of smooth-spectrum foreground contamination, only the cross-power is robust to problematic non-smooth foregrounds like polarized synchrotron emission.

  18. MEASURING BARYON ACOUSTIC OSCILLATIONS ON 21 cm INTENSITY FLUCTUATIONS AT MODERATE REDSHIFTS

    SciTech Connect

    Mao Xiaochun

    2012-06-20

    After reionization, emission in the 21 cm hyperfine transition provides a direct probe of neutral hydrogen distributed in galaxies. Different from galaxy redshift surveys, observation of baryon acoustic oscillations in the cumulative 21 cm emission may offer an attractive method for constraining dark energy properties at moderate redshifts. Keys to this program are techniques to extract the faint cosmological signal from various contaminants, such as detector noise and continuum foregrounds. In this paper, we investigate the possible systematic and statistical errors in the acoustic scale estimates using ground-based radio interferometers. Based on the simulated 21 cm interferometric measurements, we analyze the performance of a Fourier-space, light-of-sight algorithm in subtracting foregrounds, and further study the observing strategy as a function of instrumental configurations. Measurement uncertainties are presented from a suite of simulations with a variety of parameters, in order to have an estimate of what behaviors will be accessible in the future generation of hydrogen surveys. We find that 10 separate interferometers, each of which contains {approx}300 dishes, observing an independent patch of the sky and producing an instantaneous field of view (FOV) of {approx}100 deg{sup 2}, can be used to make a significant detection of acoustic features over a period of a few years. Compared to optical surveys, the broad bandwidth, wide FOV, and multi-beam observation are all unprecedented capabilities of low-frequency radio experiments.

  19. Searching for signatures of cosmic string wakes in 21cm redshift surveys using Minkowski Functionals

    SciTech Connect

    McDonough, Evan; Brandenberger, Robert H. E-mail: rhb@hep.physics.mcgill.ca

    2013-02-01

    Minkowski Functionals are a powerful tool for analyzing large scale structure, in particular if the distribution of matter is highly non-Gaussian, as it is in models in which cosmic strings contribute to structure formation. Here we apply Minkowski functionals to 21cm maps which arise if structure is seeded by a scaling distribution of cosmic strings embeddded in background fluctuations, and then test for the statistical significance of the cosmic string signals using the Fisher combined probability test. We find that this method allows for detection of cosmic strings with Gμ > 5 × 10{sup −8}, which would be improvement over current limits by a factor of about 3.

  20. A comparative study of intervening and associated H I 21-cm absorption profiles in redshifted galaxies

    NASA Astrophysics Data System (ADS)

    Curran, S. J.; Duchesne, S. W.; Divoli, A.; Allison, J. R.

    2016-08-01

    The star-forming reservoir in the distant Universe can be detected through H I 21-cm absorption arising from either cool gas associated with a radio source or from within a galaxy intervening the sight-line to the continuum source. In order to test whether the nature of the absorber can be predicted from the profile shape, we have compiled and analysed all of the known redshifted (z ≥ 0.1) H I 21-cm absorption profiles. Although between individual spectra there is too much variation to assign a typical spectral profile, we confirm that associated absorption profiles are, on average, wider than their intervening counterparts. It is widely hypothesised that this is due to high velocity nuclear gas feeding the central engine, absent in the more quiescent intervening absorbers. Modelling the column density distribution of the mean associated and intervening spectra, we confirm that the additional low optical depth, wide dispersion component, typical of associated absorbers, arises from gas within the inner parsec. With regard to the potential of predicting the absorber type in the absence of optical spectroscopy, we have implemented machine learning techniques to the 55 associated and 43 intervening spectra, with each of the tested models giving a ≳80% accuracy in the prediction of the absorber type. Given the impracticability of follow-up optical spectroscopy of the large number of 21-cm detections expected from the next generation of large radio telescopes, this could provide a powerful new technique with which to determine the nature of the absorbing galaxy.

  1. A comparative study of intervening and associated H I 21-cm absorption profiles in redshifted galaxies

    NASA Astrophysics Data System (ADS)

    Curran, S. J.; Duchesne, S. W.; Divoli, A.; Allison, J. R.

    2016-11-01

    The star-forming reservoir in the distant Universe can be detected through H I 21-cm absorption arising from either cool gas associated with a radio source or from within a galaxy intervening the sightline to the continuum source. In order to test whether the nature of the absorber can be predicted from the profile shape, we have compiled and analysed all of the known redshifted (z ≥ 0.1) H I 21-cm absorption profiles. Although between individual spectra there is too much variation to assign a typical spectral profile, we confirm that associated absorption profiles are, on average, wider than their intervening counterparts. It is widely hypothesized that this is due to high-velocity nuclear gas feeding the central engine, absent in the more quiescent intervening absorbers. Modelling the column density distribution of the mean associated and intervening spectra, we confirm that the additional low optical depth, wide dispersion component, typical of associated absorbers, arises from gas within the inner parsec. With regard to the potential of predicting the absorber type in the absence of optical spectroscopy, we have implemented machine learning techniques to the 55 associated and 43 intervening spectra, with each of the tested models giving a ≳ 80 per cent accuracy in the prediction of the absorber type. Given the impracticability of follow-up optical spectroscopy of the large number of 21-cm detections expected from the next generation of large radio telescopes, this could provide a powerful new technique with which to determine the nature of the absorbing galaxy.

  2. Distinctive rings in the 21 cm signal of the epoch of reionization

    NASA Astrophysics Data System (ADS)

    Vonlanthen, P.; Semelin, B.; Baek, S.; Revaz, Y.

    2011-08-01

    Context. It is predicted that sources emitting UV radiation in the Lyman band during the epoch of reionization show a series of discontinuities in their Lyα flux radial profile as a consequence of the thickness of the Lyman-series lines in the primeval intergalactic medium. Through unsaturated Wouthuysen-Field coupling, these spherical discontinuities are also present in the 21 cm emission of the neutral IGM. Aims: We study the effects that these discontinuities have on the differential brightness temperature of the 21 cm signal of neutral hydrogen in a realistic setting that includes all other sources of fluctuations. We focus on the early phases of the epoch of reionization, and we address the question of the detectability by the planned Square Kilometre Array (SKA). Such a detection would be of great interest because these structures could provide an unambiguous diagnostic tool for the cosmological origin of the signal that remains after the foreground cleaning procedure. These structures could also be used as a new type of standard rulers. Methods: We determine the differential brightness temperature of the 21 cm signal in the presence of inhomogeneous Wouthuysen-Field effect using simulations that include (hydro)dynamics as well as ionizing and Lyman lines 3D radiative transfer with the code LICORICE. We include radiative transfer for the higher-order Lyman-series lines and consider also the effect of backreaction from recoils and spin diffusivity on the Lyα resonance. Results: We find that the Lyman horizons are difficult to indentify using the power spectrum of the 21 cm signal but are clearly visible in the maps and radial profiles around the first sources of our simulations, if only for a limited time interval, typically Δz ≈ 2 at z ~ 13. Stacking the profiles of the different sources of the simulation at a given redshift results in extending this interval to Δz ≈ 4. When we take into account the implementation and design planned for the SKA

  3. The CMBR ISW and HI 21 cm cross-correlation angular power spectrum

    SciTech Connect

    Sarkar, Tapomoy Guha; Datta, Kanan K.; Bharadwaj, Somnath E-mail: kanan@cts.iitkgp.ernet.in

    2009-08-01

    The late-time growth of large scale structures is imprinted in the CMBR anisotropy through the Integrated Sachs Wolfe (ISW) effect. This is perceived to be a very important observational probe of dark energy. Future observations of redshifted 21-cm radiation from the cosmological neutral hydrogen (HI) distribution hold the potential of probing the large scale structure over a large redshift range. We have investigated the possibility of detecting the ISW through cross-correlations between the CMBR anisotropies and redshifted 21-cm observations. Assuming that the HI traces the dark matter, we find that the ISW-HI cross-correlation angular power spectrum at an angular multipole l is proportional to the dark matter power spectrum evaluated at the comoving wave number l/r, where r is the comoving distance to the redshift from which the HI signal originated. The amplitude of the cross-correlation signal depends on parameters related to the HI distribution and the growth of cosmological perturbations. However, the cross-correlation is extremely weak as compared to the CMBR anisotropies and the predicted HI signal. Even in an ideal situation, the cross-correlation signal is smaller than the cosmic variance and a statistically significant detection is not very likely.

  4. 21 cm Fluctuations of the Cosmic Dawn with the Owens Valley Long Wavelength Array

    NASA Astrophysics Data System (ADS)

    Eastwood, Michael; Hallinan, Gregg; Owens Valley LWA Collaboration

    2016-01-01

    The Owens Valley Long Wavelength Array (OVRO LWA) is a 288-antenna interferometer covering 30 to 80 MHz located at the Owens Valley Radio Observatory (OVRO) near Big Pine, California. I am leading the effort to detect spatial fluctuations of the 21 cm transition from the cosmic dawn (z~20) with the OVRO LWA. These spatial fluctuations are primarily sourced by inhomogeneous X-ray heating from early star formation. The spectral hardness of early X-ray sources, stellar feedback mechanisms, and baryon streaming therefore all play a role in shaping the power spectrum. I will present the application of m-mode analysis (Shaw et al. 2014, Shaw et al. 2015) to OVRO LWA data to: 1. compress the data set, 2. create maps of the northern sky that can be fed back into the calibration pipeline, and 3. filter foreground emission. Finally I will present the current status and future prospects of the OVRO LWA for detecting the 21 cm power spectrum at z~20.

  5. Pilot observations at 74 MHz for global 21cm cosmology with the Parkes 64 m

    NASA Astrophysics Data System (ADS)

    Bannister, Keith; McConnell, David; Reynolds, John; Chippendale, Aaron; Landecker, Tom L.; Dunning, Alex

    2013-10-01

    We propose a single pilot observing session using the existing 74 MHz feed at Parkes to evaluate tools and techniques to optimise low frequency (44-88 MHz) observing. 1. A continuum map of the diffuse emission in the Southern sky at 74 MHz. Such a map would be of great help to single-dipole 21cm cosmology experiments, whose diffuse Galactic foregrounds are currently poorly constrained (Pritchard & Loeb, 2010b; de Oliveira-Costa et al., 2008). 2. A wideband (44-88 MHz) map of of the Southern sky, which can be used as a direct detection of the dark ages global signal. Recent theoretical work has shown that the Parkes aperture of 64 m is the optimal size for such a direct detection, which could be achieved at 25? in as little as 100 hrs of observing (Liu et al., 2012). After receiving a 4.1 grade in the previous round, our observations were not scheduled due to limited receiver changes. We are therefore re-proposing as formality. Since the proposal, we have obtained RFI measurements with the feed pointed at zenith. We are confident the dominant source of RFI can be found and removed. If observing at this band is possible, at least two scientific outputs relevant to global 21cm cosmology (among many others) are put within reach:

  6. The Evolution Of 21 cm Structure (EOS): public, large-scale simulations of Cosmic Dawn and reionization

    NASA Astrophysics Data System (ADS)

    Mesinger, Andrei; Greig, Bradley; Sobacchi, Emanuele

    2016-07-01

    We introduce the Evolution Of 21 cm Structure (EOS) project: providing periodic, public releases of the latest cosmological 21 cm simulations. 21 cm interferometry is set to revolutionize studies of the Cosmic Dawn (CD) and Epoch of Reionization (EoR). Progress will depend on sophisticated data analysis pipelines, initially tested on large-scale mock observations. Here we present the 2016 EOS release: 10243, 1.6 Gpc, 21 cm simulations of the CD and EoR, calibrated to the Planck 2015 measurements. We include calibrated, sub-grid prescriptions for inhomogeneous recombinations and photoheating suppression of star formation in small-mass galaxies. Leaving the efficiency of supernovae feedback as a free parameter, we present two runs which bracket the contribution from faint unseen galaxies. From these two extremes, we predict that the duration of reionization (defined as a change in the mean neutral fraction from 0.9 to 0.1) should be between 2.7 ≲ Δzre ≲ 5.7. The large-scale 21 cm power during the advanced EoR stages can be different by up to a factor of ˜10, depending on the model. This difference has a comparable contribution from (i) the typical bias of sources and (ii) a more efficient negative feedback in models with an extended EoR driven by faint galaxies. We also present detectability forecasts. With a 1000 h integration, Hydrogen Epoch of Reionization Array and (Square Kilometre Array phase 1) SKA1 should achieve a signal-to-noise of ˜few to hundreds throughout the EoR/CD. We caution that our ability to clean foregrounds determines the relative performance of narrow/deep versus wide/shallow surveys expected with SKA1. Our 21-cm power spectra, simulation outputs and visualizations are publicly available.

  7. Signatures of clumpy dark matter in the global 21 cm background signal

    SciTech Connect

    Cumberbatch, Daniel T.; Lattanzi, Massimiliano; Silk, Joseph

    2010-11-15

    We examine the extent to which the self-annihilation of supersymmetric neutralino dark matter, as well as light dark matter, influences the rate of heating, ionization, and Lyman-{alpha} pumping of interstellar hydrogen and helium and the extent to which this is manifested in the 21 cm global background signal. We fully consider the enhancements to the annihilation rate from dark matter halos and substructures within them. We find that the influence of such structures can result in significant changes in the differential brightness temperature, {delta}T{sub b}. The changes at redshifts z<25 are likely to be undetectable due to the presence of the astrophysical signal; however, in the most favorable cases, deviations in {delta}T{sub b}, relative to its value in the absence of self-annihilating dark matter, of up to {approx_equal}20 mK at z=30 can occur. Thus we conclude that, in order to exclude these models, experiments measuring the global 21 cm signal, such as EDGES and CORE, will need to reduce the systematics at 50 MHz to below 20 mK.

  8. Dicke’s Superradiance in Astrophysics. I. The 21 cm Line

    NASA Astrophysics Data System (ADS)

    Rajabi, Fereshteh; Houde, Martin

    2016-08-01

    We have applied the concept of superradiance introduced by Dicke in 1954 to astrophysics by extending the corresponding analysis to the magnetic dipole interaction characterizing the atomic hydrogen 21 cm line. Although it is unlikely that superradiance could take place in thermally relaxed regions and that the lack of observational evidence of masers for this transition reduces the probability of detecting superradiance, in situations where the conditions necessary for superradiance are met (close atomic spacing, high velocity coherence, population inversion, and long dephasing timescales compared to those related to coherent behavior), our results suggest that relatively low levels of population inversion over short astronomical length-scales (e.g., as compared to those required for maser amplification) can lead to the cooperative behavior required for superradiance in the interstellar medium. Given the results of our analysis, we expect the observational properties of 21 cm superradiance to be characterized by the emission of high-intensity, spatially compact, burst-like features potentially taking place over short periods ranging from minutes to days.

  9. Lyman-alpha radiative transfer during the epoch of reionization: contribution to 21-cm signal fluctuations

    NASA Astrophysics Data System (ADS)

    Semelin, B.; Combes, F.; Baek, S.

    2007-11-01

    During the epoch of reionization, Ly-α photons emitted by the first stars can couple the neutral hydrogen spin temperature to the kinetic gas temperature, providing an opportunity to observe the gas in emission or absorption in the 21-cm line. Given the bright foregrounds, it is particularly important to determine the fluctuation signature of the signal precisely, so as to be able to extract it by its correlation power. LICORICE is a Monte-Carlo radiative transfer code, coupled to the dynamics via an adaptative Tree-SPH code. We present here the Ly-α part of the implementation and validate it through three classical tests. Unlike previous works, we do not assume that P_α, the number of scatterings of Ly-α photons per atom per second, is proportional to the Ly-α background flux, but take the scatterings in the Ly-α line wings into account. The latter have the effect of steepening the radial profile of P_α around each source, and re-inforce the contrast of the fluctuations. In the particular geometry of cosmic filaments of baryonic matter, Ly-α photons are scattered out of the filament, and the large-scale structure of P_α is significantly anisotropic. This could have strong implications for the possible detection of the 21-cm signal.

  10. PAPER-64 Constraints on Reionization: The 21 cm Power Spectrum at z = 8.4

    NASA Astrophysics Data System (ADS)

    Ali, Zaki S.; Parsons, Aaron R.; Zheng, Haoxuan; Pober, Jonathan C.; Liu, Adrian; Aguirre, James E.; Bradley, Richard F.; Bernardi, Gianni; Carilli, Chris L.; Cheng, Carina; DeBoer, David R.; Dexter, Matthew R.; Grobbelaar, Jasper; Horrell, Jasper; Jacobs, Daniel C.; Klima, Pat; MacMahon, David H. E.; Maree, Matthys; Moore, David F.; Razavi, Nima; Stefan, Irina I.; Walbrugh, William P.; Walker, Andre

    2015-08-01

    In this paper, we report new limits on 21 cm emission from cosmic reionization based on a 135 day observing campaign with a 64-element deployment of the Donald C. Backer Precision Array for Probing the Epoch of Reionization in South Africa. This work extends the work presented in Parsons et al. with more collecting area, a longer observing period, improved redundancy-based calibration, improved fringe-rate filtering, and updated power-spectral analysis using optimal quadratic estimators. The result is a new 2σ upper limit on Δ2(k) of (22.4 mK)2 in the range 0.15\\lt k\\lt 0.5h {{Mpc}}-1 at z = 8.4. This represents a three-fold improvement over the previous best upper limit. As we discuss in more depth in a forthcoming paper, this upper limit supports and extends previous evidence against extremely cold reionization scenarios. We conclude with a discussion of implications for future 21 cm reionization experiments, including the newly funded Hydrogen Epoch of Reionization Array.

  11. A new Tolman test of a cosmic distance duality relation at 21 cm.

    PubMed

    Khedekar, Satej; Chakraborti, Sayan

    2011-06-01

    Under certain general conditions in an expanding universe, the luminosity distance (d(L)) and angular diameter distance (d(A)) are connected by the Etherington relation as d(L)=d(A)(1+z)2. The Tolman test suggests the use of objects of known surface brightness, to test this relation. In this Letter, we propose the use of a redshifted 21 cm signal from disk galaxies, where neutral hydrogen (HI) masses are seen to be almost linearly correlated with surface area, to conduct a new Tolman test. We construct simulated catalogs of galaxies, with the observed size-luminosity relation and realistic redshift evolution of HI mass functions, likely to be detected with the planned Square Kilometer Array. We demonstrate that these observations may soon provide the best implementation of the Tolman test to detect any violation of the cosmic distance duality relation.

  12. NEW EVIDENCE FOR MASS LOSS FROM {delta} CEPHEI FROM H I 21 cm LINE OBSERVATIONS

    SciTech Connect

    Matthews, L. D.; Marengo, M.; Evans, N. R.; Bono, G.

    2012-01-01

    Recently published Spitzer Space Telescope observations of the classical Cepheid archetype {delta} Cephei revealed an extended dusty nebula surrounding this star and its hot companion HD 213307. At far-infrared wavelengths, the emission resembles a bow shock aligned with the direction of space motion of the star, indicating that {delta} Cephei is undergoing mass loss through a stellar wind. Here we report H I 21 cm line observations with the Very Large Array (VLA) to search for neutral atomic hydrogen associated with this wind. Our VLA data reveal a spatially extended H I nebula ({approx}13' or 1 pc across) surrounding the position of {delta} Cephei. The nebula has a head-tail morphology, consistent with circumstellar ejecta shaped by the interaction between a stellar wind and the interstellar medium (ISM). We directly measure a mass of circumstellar atomic hydrogen M{sub H{sub i}}{approx}0.07 M{sub sun}, although the total H I mass may be larger, depending on the fraction of circumstellar material that is hidden by Galactic contamination within our band or that is present on angular scales too large to be detected by the VLA. It appears that the bulk of the circumstellar gas has originated directly from the star, although it may be augmented by material swept from the surrounding ISM. The H I data are consistent with a stellar wind with an outflow velocity V{sub o} = 35.6 {+-} 1.2 km s{sup -1} and a mass-loss rate of M-dot {approx}(1.0{+-}0.8) Multiplication-Sign 10{sup -6} M{sub sun} yr{sup -1}. We have computed theoretical evolutionary tracks that include mass loss across the instability strip and show that a mass-loss rate of this magnitude, sustained over the preceding Cepheid lifetime of {delta} Cephei, could be sufficient to resolve a significant fraction of the discrepancy between the pulsation and evolutionary masses for this star.

  13. Method for Direct Measurement of Cosmic Acceleration by 21-cm Absorption Systems

    NASA Astrophysics Data System (ADS)

    Yu, Hao-Ran; Zhang, Tong-Jie; Pen, Ue-Li

    2014-07-01

    So far there is only indirect evidence that the Universe is undergoing an accelerated expansion. The evidence for cosmic acceleration is based on the observation of different objects at different distances and requires invoking the Copernican cosmological principle and Einstein's equations of motion. We examine the direct observability using recession velocity drifts (Sandage-Loeb effect) of 21-cm hydrogen absorption systems in upcoming radio surveys. This measures the change in velocity of the same objects separated by a time interval and is a model-independent measure of acceleration. We forecast that for a CHIME-like survey with a decade time span, we can detect the acceleration of a ΛCDM universe with 5σ confidence. This acceleration test requires modest data analysis and storage changes from the normal processing and cannot be recovered retroactively.

  14. Using 21 cm absorption surveys to measure the average H I spin temperature in distant galaxies

    NASA Astrophysics Data System (ADS)

    Allison, J. R.; Zwaan, M. A.; Duchesne, S. W.; Curran, S. J.

    2016-10-01

    We present a statistical method for measuring the average H I spin temperature in distant galaxies using the expected detection yields from future wide-field 21 cm absorption surveys. As a demonstrative case study, we consider an all-southern-sky simulated survey of 2-h per pointing with the Australian Square Kilometre Array Pathfinder for intervening H I absorbers at intermediate cosmological redshifts between z = 0.4 and 1. For example, if such a survey yielded 1000 absorbers, we would infer a harmonic-mean spin temperature of overline{T}_spin ˜ 100 K for the population of damped Lyman α absorbers (DLAs) at these redshifts, indicating that more than 50 per cent of the neutral gas in these systems is in a cold neutral medium (CNM). Conversely, a lower yield of only 100 detections would imply overline{T}_spin ˜ 1000 K and a CNM fraction less than 10 per cent. We propose that this method can be used to provide independent verification of the spin temperature evolution reported in recent 21 cm surveys of known DLAs at high redshift and for measuring the spin temperature at intermediate redshifts below z ≈ 1.7, where the Lyman α line is inaccessible using ground-based observatories. Increasingly more sensitive and larger surveys with the Square Kilometre Array should provide stronger statistical constraints on the average spin temperature. However, these will ultimately be limited by the accuracy to which we can determine the H I column density frequency distribution, the covering factor and the redshift distribution of the background radio source population.

  15. Angular 21 cm power spectrum of a scaling distribution of cosmic string wakes

    SciTech Connect

    Hernández, Oscar F.; Wang, Yi; Brandenberger, Robert; Fong, José E-mail: wangyi@physics.mcgill.ca E-mail: jose.fong@ens-lyon.fr

    2011-08-01

    Cosmic string wakes lead to a large signal in 21 cm redshift maps at redshifts larger than that corresponding to reionization. Here, we compute the angular power spectrum of 21 cm radiation as predicted by a scaling distribution of cosmic strings whose wakes have undergone shock heating.

  16. First limits on the 21 cm power spectrum during the Epoch of X-ray heating

    NASA Astrophysics Data System (ADS)

    Ewall-Wice, A.; Dillon, Joshua S.; Hewitt, J. N.; Loeb, A.; Mesinger, A.; Neben, A. R.; Offringa, A. R.; Tegmark, M.; Barry, N.; Beardsley, A. P.; Bernardi, G.; Bowman, Judd D.; Briggs, F.; Cappallo, R. J.; Carroll, P.; Corey, B. E.; de Oliveira-Costa, A.; Emrich, D.; Feng, L.; Gaensler, B. M.; Goeke, R.; Greenhill, L. J.; Hazelton, B. J.; Hurley-Walker, N.; Johnston-Hollitt, M.; Jacobs, Daniel C.; Kaplan, D. L.; Kasper, J. C.; Kim, HS; Kratzenberg, E.; Lenc, E.; Line, J.; Lonsdale, C. J.; Lynch, M. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Thyagarajan, Nithyanandan; Oberoi, D.; Ord, S. M.; Paul, S.; Pindor, B.; Pober, J. C.; Prabu, T.; Procopio, P.; Riding, J.; Rogers, A. E. E.; Roshi, A.; Shankar, N. Udaya; Sethi, Shiv K.; Srivani, K. S.; Subrahmanyan, R.; Sullivan, I. S.; Tingay, S. J.; Trott, C. M.; Waterson, M.; Wayth, R. B.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.; Wu, C.; Wyithe, J. S. B.

    2016-08-01

    We present first results from radio observations with the Murchison Widefield Array seeking to constrain the power spectrum of 21 cm brightness temperature fluctuations between the redshifts of 11.6 and 17.9 (113 and 75 MHz). 3 h of observations were conducted over two nights with significantly different levels of ionospheric activity. We use these data to assess the impact of systematic errors at low frequency, including the ionosphere and radio-frequency interference, on a power spectrum measurement. We find that after the 1-3 h of integration presented here, our measurements at the Murchison Radio Observatory are not limited by RFI, even within the FM band, and that the ionosphere does not appear to affect the level of power in the modes that we expect to be sensitive to cosmology. Power spectrum detections, inconsistent with noise, due to fine spectral structure imprinted on the foregrounds by reflections in the signal-chain, occupy the spatial Fourier modes where we would otherwise be most sensitive to the cosmological signal. We are able to reduce this contamination using calibration solutions derived from autocorrelations so that we achieve an sensitivity of 104 mK on comoving scales k ≲ 0.5 h Mpc-1. This represents the first upper limits on the 21 cm power spectrum fluctuations at redshifts 12 ≲ z ≲ 18 but is still limited by calibration systematics. While calibration improvements may allow us to further remove this contamination, our results emphasize that future experiments should consider carefully the existence of and their ability to calibrate out any spectral structure within the EoR window.

  17. The Murchison Widefield Array 21cm Epoch of Reionization Experiment: Design, Construction, and First Season Results

    NASA Astrophysics Data System (ADS)

    Beardsley, Adam

    The Cosmic Dark Ages and the Epoch of Reionization (EoR) remain largely unexplored chapters in the history and evolution of the Universe. These periods hold the potential to inform our picture of the cosmos similar to what the Cosmic Microwave Background has done over the past several decades. A promising method to probe the neutral hydrogen gas between early galaxies is known as 21cm tomography, which utilizes the ubiquitous hyper-fine transition of HI to create 3D maps of the intergalactic medium. The Murchison Widefield Array (MWA) is an instrument built with a primary science driver to detect and characterize the EoR through 21cm tomography. In this thesis we explore the challenges faced by the MWA from the layout of antennas, to a custom analysis pipeline, to bridging the gap with probes at other wavelengths. We discuss many lessons learned in the course of reducing MWA data with an extremely precise measurement in mind, and conclude with the first deep integration from array. We present a 2-σ upper limit on the EoR power spectrum of Δ^2(k)<1.25×10^4 mK^2 at cosmic scale k=0.236 h Mpc^{-1} and redshift z=6.8. Our result is a marginal improvement over previous MWA results and consistent with the best published limits from other instruments. This result is the deepest imaging power spectrum to date, and is a major step forward for this type of analysis. While our limit is dominated by systematics, we offer strategies for improvement for future analysis.

  18. The Murchison Widefield Array 21cm Epoch of Reionization Experiment: Design, Construction, and First Season Results

    NASA Astrophysics Data System (ADS)

    Beardsley, Adam

    The Cosmic Dark Ages and the Epoch of Reionization (EoR) remain largely unexplored chapters in the history and evolution of the Universe. These periods hold the potential to inform our picture of the cosmos similar to what the Cosmic Microwave Background has done over the past several decades. A promising method to probe the neutral hydrogen gas between early galaxies is known as 21cm tomography, which utilizes the ubiquitous hyper-fine transition of HI to create 3D maps of the intergalactic medium. The Murchison Widefield Array (MWA) is an instrument built with a primary science driver to detect and characterize the EoR through 21cm tomography. In this thesis we explore the challenges faced by the MWA from the layout of antennas, to a custom analysis pipeline, to bridging the gap with probes at other wavelengths. We discuss many lessons learned in the course of reducing MWA data with an extremely precise measurement in mind, and conclude with the first deep integration from array. We present a 2-sigma upper limit on the EoR power spectrum of Delta2(k) < 1.25 x 104 mK2 at cosmic scale k = 0.236 h Mpc-1 and redshift z = 6.8. Our result is a marginal improvement over previous MWA results and consistent with the best published limits from other instruments. This result is the deepest imaging power spectrum to date, and is a major step forward for this type of analysis. While our limit is dominated by systematics, we offer strategies for improvement for future analysis.

  19. Cross-correlation of 21 cm and soft X-ray backgrounds during the epoch of reionization

    NASA Astrophysics Data System (ADS)

    Liang, Jun-Min; Mao, Xiao-Chun; Qin, Bo

    2016-08-01

    The cross-correlation between the high-redshift 21 cm background and the Soft X-ray Background (SXB) of the Universe may provide an additional probe of the Epoch of Reionization. Here we use semi-numerical simulations to create 21 cm and soft X-ray intensity maps and construct their cross power spectra. Our results indicate that the cross power spectra are sensitive to the thermal and ionizing states of the intergalactic medium (IGM). The 21 cm background correlates positively to the SXB on large scales during the early stages of the reionization. However as the reionization develops, these two backgrounds turn out to be anti-correlated with each other when more than ˜ 15% of the IGM is ionized in a warm reionization scenario. The anti-correlated power reaches its maximum when the neutral fraction declines to 0.2-0.5. Hence, the trough in the cross power spectrum might be a useful tool for tracing the growth of HII regions during the middle and late stages of the reionization. We estimate the detectability of the cross power spectrum based on the abilities of the Square Kilometre Array and the Wide Field X-ray Telescope (WFXT), and find that to detect the cross power spectrum, the pixel noise of X-ray images has to be at least 4 orders of magnitude lower than that of the WFXT deep survey.

  20. Cross-correlation of 21 cm and soft X-ray backgrounds during the epoch of reionization

    NASA Astrophysics Data System (ADS)

    Liang, Jun-Min; Mao, Xiao-Chun; Qin, Bo

    2016-08-01

    The cross-correlation between the high-redshift 21 cm background and the Soft X-ray Background (SXB) of the Universe may provide an additional probe of the Epoch of Reionization. Here we use semi-numerical simulations to create 21 cm and soft X-ray intensity maps and construct their cross power spectra. Our results indicate that the cross power spectra are sensitive to the thermal and ionizing states of the intergalactic medium (IGM). The 21 cm background correlates positively to the SXB on large scales during the early stages of the reionization. However as the reionization develops, these two backgrounds turn out to be anti-correlated with each other when more than ∼ 15% of the IGM is ionized in a warm reionization scenario. The anti-correlated power reaches its maximum when the neutral fraction declines to 0.2–0.5. Hence, the trough in the cross power spectrum might be a useful tool for tracing the growth of HII regions during the middle and late stages of the reionization. We estimate the detectability of the cross power spectrum based on the abilities of the Square Kilometre Array and the Wide Field X-ray Telescope (WFXT), and find that to detect the cross power spectrum, the pixel noise of X-ray images has to be at least 4 orders of magnitude lower than that of the WFXT deep survey.

  1. Hydrogen and the First Stars: First Results from the SCI-HI 21-cm all-sky spectrum experiment

    NASA Astrophysics Data System (ADS)

    Voytek, Tabitha; Peterson, Jeffrey; Lopez-Cruz, Omar; Jauregui-Garcia, Jose-Miguel; SCI-HI Experiment Team

    2015-01-01

    The 'Sonda Cosmologica de las Islas para la Deteccion de Hidrogeno Neutro' (SCI-HI) experiment is an all-sky 21-cm brightness temperature spectrum experiment studying the cosmic dawn (z~15-35). The experiment is a collaboration between Carnegie Mellon University (CMU) and Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE) in Mexico. Initial deployment of the SCI-HI experiment occurred in June 2013 on Guadalupe; a small island about 250 km off of the Pacific coast of Baja California in Mexico. Preliminary measurements from this deployment have placed the first observational constraints on the 21-cm all-sky spectrum around 70 MHz (z~20), see Voytek et al (2014).Neutral Hydrogen (HI) is found throughout the universe in the cold gas that makes up the intergalactic medium (IGM). HI can be observed through the spectral line at 21 cm (1.4 GHz) due to hyperfine structure. Expansion of the universe causes the wavelength of this spectral line to stretch at a rate defined by the redshift z, leading to a signal which can be followed through time.Now the strength of the 21-cm signal in the IGM is dependent only on a small number of variables; the temperature and density of the IGM, the amount of HI in the IGM, the UV energy density in the IGM, and the redshift. This means that 21-cm measurements teach us about the history and structure of the IGM. The SCI-HI experiment focuses on the spatially averaged 21-cm spectrum, looking at the temporal evolution of the IGM during the cosmic dawn before reionization.Although the SCI-HI experiment placed first constraints with preliminary data, this data was limited to a narrow frequency regime around 60-85 MHz. This limitation was caused by instrumental difficulties and the presence of residual radio frequency interference (RFI) in the FM radio band (~88-108 MHz). The SCI-HI experiment is currently undergoing improvements and we plan to have another deployment soon. This deployment would be to Socorro and Clarion, two

  2. The cross correlation between the 21-cm radiation and the CMB lensing field: a new cosmological signal

    SciTech Connect

    Vallinotto, Alberto

    2011-01-01

    The measurement of Baryon Acoustic Oscillations through the 21-cm intensity mapping technique at redshift z {<=} 4 has the potential to tightly constrain the evolution of dark energy. Crucial to this experimental effort is the determination of the biasing relation connecting fluctuations in the density of neutral hydrogen (HI) with the ones of the underlying dark matter field. In this work I show how the HI bias relevant to these 21-cm intensity mapping experiments can successfully be measured by cross-correlating their signal with the lensing signal obtained from CMB observations. In particular I show that combining CMB lensing maps from Planck with 21-cm field measurements carried out with an instrument similar to the Cylindrical Radio Telescope, this cross-correlation signal can be detected with a signal-to-noise (S/N) ratio of more than 5. Breaking down the signal arising from different redshift bins of thickness {Delta}z = 0.1, this signal leads to constraining the large scale neutral hydrogen bias and its evolution to 4{sigma} level.

  3. Reconstructing the nature of the first cosmic sources from the anisotropic 21-cm signal.

    PubMed

    Fialkov, Anastasia; Barkana, Rennan; Cohen, Aviad

    2015-03-13

    The redshifted 21-cm background is expected to be a powerful probe of the early Universe, carrying both cosmological and astrophysical information from a wide range of redshifts. In particular, the power spectrum of fluctuations in the 21-cm brightness temperature is anisotropic due to the line-of-sight velocity gradient, which in principle allows for a simple extraction of this information in the limit of linear fluctuations. However, recent numerical studies suggest that the 21-cm signal is actually rather complex, and its analysis likely depends on detailed model fitting. We present the first realistic simulation of the anisotropic 21-cm power spectrum over a wide period of early cosmic history. We show that on observable scales, the anisotropy is large and thus measurable at most redshifts, and its form tracks the evolution of 21-cm fluctuations as they are produced early on by Lyman-α radiation from stars, then switch to x-ray radiation from early heating sources, and finally to ionizing radiation from stars. In particular, we predict a redshift window during cosmic heating (at z∼15), when the anisotropy is small, during which the shape of the 21-cm power spectrum on large scales is determined directly by the average radial distribution of the flux from x-ray sources. This makes possible a model-independent reconstruction of the x-ray spectrum of the earliest sources of cosmic heating.

  4. RESEARCH PAPER: Foreground removal of 21 cm fluctuation with multifrequency fitting

    NASA Astrophysics Data System (ADS)

    He, Li-Ping

    2009-06-01

    The 21 centimeter (21 cm) line emission from neutral hydrogen in the intergalactic medium (IGM) at high redshifts is strongly contaminated by foreground sources such as the diffuse Galactic synchrotron emission and free-free emission from the Galaxy, as well as emission from extragalactic radio sources, thus making its observation very complicated. However, the 21 cm signal can be recovered through its structure in frequency space, as the power spectrum of the foreground contamination is expected to be smooth over a wide band in frequency space while the 21 cm fluctuations vary significantly. We use a simple polynomial fitting to reconstruct the 21 cm signal around four frequencies 50, 100, 150 and 200MHz with an especially small channel width of 20 kHz. Our calculations show that this multifrequency fitting approach can effectively recover the 21 cm signal in the frequency range 100 ~ 200 MHz. However, this method doesn't work well around 50 MHz because of the low intensity of the 21 cm signal at this frequency. We also show that the fluctuation of detector noise can be suppressed to a very low level by taking long integration times, which means that we can reach a sensitivity of approx10 mK at 150 MHz with 40 antennas in 120 hours of observations.

  5. Radio frequency interference at Jodrell Bank Observatory within the protected 21 cm band.

    PubMed

    Tarter, J

    1989-01-01

    Radio frequency interference (RFI) will provide one of the most difficult challenges to systematic Searches for Extraterrestrial Intelligence (SETI) at microwave frequencies. The SETI-specific equipment is being optimized for the detection of signals generated by a technology rather than those generated by natural processes in the universe. If this equipment performs as expected, then it will inevitably detect many signals originating from terrestrial technology. If these terrestrial signals are too numerous and/or strong, the equipment will effectively be blinded to the (presumably) weaker extraterrestrial signals being sought. It is very difficult to assess how much of a problem RFI will actually represent to future observations, without employing the equipment and beginning the search. In 1983 a very high resolution spectrometer was placed at the Nuffield Radio Astronomy Laboratories at Jodrell Bank, England. This equipment permitted an investigation of the interference environment at Jodrell Bank, at that epoch, and at frequencies within the 21 cm band. This band was chosen because it has long been "protected" by international agreement; no transmitters should have been operating at those frequencies. The data collected at Jodrell Bank were expected to serve as a "best case" interference scenario and provide the minimum design requirements for SETI equipment that must function in the real and noisy environment. This paper describes the data collection and analysis along with some preliminary conclusions concerning the nature of the interference environment at Jodrell Bank.

  6. A Giant Metrewave Radio Telescope search for associated H I 21 cm absorption in high-redshift flat-spectrum sources

    NASA Astrophysics Data System (ADS)

    Aditya, J. N. H. S.; Kanekar, Nissim; Kurapati, Sushma

    2016-02-01

    We report results from a Giant Metrewave Radio Telescope search for `associated' redshifted H I 21 cm absorption from 24 active galactic nuclei (AGNs), at 1.1 < z < 3.6, selected from the Caltech-Jodrell Bank Flat-spectrum (CJF) sample. 22 out of 23 sources with usable data showed no evidence of absorption, with typical 3σ optical depth detection limits of ≈0.01 at a velocity resolution of ≈30 km s-1. A single tentative absorption detection was obtained at z ≈ 3.530 towards TXS 0604+728. If confirmed, this would be the highest redshift at which H I 21 cm absorption has ever been detected. Including 29 CJF sources with searches for redshifted H I 21 cm absorption in the literature, mostly at z < 1, we construct a sample of 52 uniformly selected flat-spectrum sources. A Peto-Prentice two-sample test for censored data finds (at ≈3σ significance) that the strength of H I 21 cm absorption is weaker in the high-z sample than in the low-z sample; this is the first statistically significant evidence for redshift evolution in the strength of H I 21 cm absorption in a uniformly selected AGN sample. However, the two-sample test also finds that the H I 21 cm absorption strength is higher in AGNs with low ultraviolet or radio luminosities, at ≈3.4σ significance. The fact that the higher luminosity AGNs of the sample typically lie at high redshifts implies that it is currently not possible to break the degeneracy between AGN luminosity and redshift evolution as the primary cause of the low H I 21 cm opacities in high-redshift, high-luminosity AGNs.

  7. Scintillation noise power spectrum and its impact on high-redshift 21-cm observations

    NASA Astrophysics Data System (ADS)

    Vedantham, H. K.; Koopmans, L. V. E.

    2016-05-01

    Visibility scintillation resulting from wave propagation through the turbulent ionosphere can be an important source of noise at low radio frequencies (ν ≲ 200 MHz). Many low-frequency experiments are underway to detect the power spectrum of brightness temperature fluctuations of the neutral-hydrogen 21-cm signal from the Epoch of Reionization (EoR: 12 ≳ z ≳ 7, 100 ≲ ν ≲ 175 MHz). In this paper, we derive scintillation noise power spectra in such experiments while taking into account the effects of typical data processing operations such as self-calibration and Fourier synthesis. We find that for minimally redundant arrays such as LOFAR and MWA, scintillation noise is of the same order of magnitude as thermal noise, has a spectral coherence dictated by stretching of the snapshot uv-coverage with frequency, and thus is confined to the well-known wedge-like structure in the cylindrical (two-dimensional) power spectrum space. Compact, fully redundant (dcore ≲ rF ≈ 300 m at 150 MHz) arrays such as HERA and SKA-LOW (core) will be scintillation noise dominated at all baselines, but the spatial and frequency coherence of this noise will allow it to be removed along with spectrally smooth foregrounds.

  8. 21-cm radiation: a new probe of variation in the fine-structure constant.

    PubMed

    Khatri, Rishi; Wandelt, Benjamin D

    2007-03-16

    We investigate the effect of variation in the value of the fine-structure constant (alpha) at high redshifts (recombination > z > 30) on the absorption of the cosmic microwave background (CMB) at 21 cm hyperfine transition of the neutral atomic hydrogen. We find that the 21 cm signal is very sensitive to the variations in alpha and it is so far the only probe of the fine-structure constant in this redshift range. A change in the value of alpha by 1% changes the mean brightness temperature decrement of the CMB due to 21 cm absorption by >5% over the redshift range z < 50. There is an effect of similar magnitude on the amplitude of the fluctuations in the brightness temperature. The redshift of maximum absorption also changes by approximately 5%.

  9. Constraining the redshifted 21-cm signal with the unresolved soft X-ray background

    NASA Astrophysics Data System (ADS)

    Fialkov, Anastasia; Cohen, Aviad; Barkana, Rennan; Silk, Joseph

    2016-10-01

    We use the observed unresolved cosmic X-ray background (CXRB) in the 0.5 - 2 keV band and existing upper limits on the 21-cm power spectrum to constrain the high-redshift population of X-ray sources, focusing on their effect on the thermal history of the Universe and the cosmic 21-cm signal. Because the properties of these sources are poorly constrained, we consider hot gas, X-ray binaries and mini-quasars (i.e., sources with soft or hard X-ray spectra) as possible candidates. We find that (1) the soft-band CXRB sets an upper limit on the X-ray efficiency of sources that existed before the end of reionization, which is one-to-two orders of magnitude higher than typically assumed efficiencies, (2) hard sources are more effective in generating the CXRB than the soft ones, (3) the commonly-assumed limit of saturated heating is not valid during the first half of reionization in the case of hard sources, with any allowed value of X-ray efficiency, (4) the maximal allowed X-ray efficiency sets a lower limit on the depth of the absorption trough in the global 21-cm signal and an upper limit on the height of the emission peak, while in the 21-cm power spectrum it sets a minimum amplitude and frequency for the high-redshift peaks, and (5) the existing upper limit on the 21-cm power spectrum sets a lower limit on the X-ray efficiency for each model. When combined with the 21-cm global signal, the CXRB will be useful for breaking degeneracies and helping constrain the nature of high-redshift heating sources.

  10. A SENSITIVITY AND ARRAY-CONFIGURATION STUDY FOR MEASURING THE POWER SPECTRUM OF 21 cm EMISSION FROM REIONIZATION

    SciTech Connect

    Parsons, Aaron; Pober, Jonathan; McQuinn, Matthew; Jacobs, Daniel; Aguirre, James

    2012-07-01

    Telescopes aiming to measure 21 cm emission from the Epoch of Reionization must toe a careful line, balancing the need for raw sensitivity against the stringent calibration requirements for removing bright foregrounds. It is unclear what the optimal design is for achieving both of these goals. Via a pedagogical derivation of an interferometer's response to the power spectrum of 21 cm reionization fluctuations, we show that even under optimistic scenarios first-generation arrays will yield low-signal-to-noise detections, and that different compact array configurations can substantially alter sensitivity. We explore the sensitivity gains of array configurations that yield high redundancy in the uv-plane-configurations that have been largely ignored since the advent of self-calibration for high-dynamic-range imaging. We first introduce a mathematical framework to generate optimal minimum-redundancy configurations for imaging. We contrast the sensitivity of such configurations with high-redundancy configurations, finding that high-redundancy configurations can improve power-spectrum sensitivity by more than an order of magnitude. We explore how high-redundancy array configurations can be tuned to various angular scales, enabling array sensitivity to be directed away from regions of the uv-plane (such as the origin) where foregrounds are brighter and instrumental systematics are more problematic. We demonstrate that a 132 antenna deployment of the Precision Array for Probing the Epoch of Reionization observing for 120 days in a high-redundancy configuration will, under ideal conditions, have the requisite sensitivity to detect the power spectrum of the 21 cm signal from reionization at a 3{sigma} level at k < 0.25 h Mpc{sup -1} in a bin of {Delta}ln k = 1. We discuss the tradeoffs of low- versus high-redundancy configurations.

  11. Sensitive 21cm Observations of Neutral Hydrogen in the Local Group near M31

    NASA Astrophysics Data System (ADS)

    Wolfe, Spencer A.; Lockman, Felix J.; Pisano, D. J.

    2016-01-01

    Very sensitive 21 cm H i measurements have been made at several locations around the Local Group galaxy M31 using the Green Bank Telescope at an angular resolution of 9.‧1, with a 5σ detection level of NH i = 3.9 × 1017 cm-2 for a 30 km s-1 line. Most of the H i in a 12 square-degree area almost equidistant between M31 and M33 is contained in nine discrete clouds that have a typical size of a few kpc and a H i mass of 105M⊙. Their velocities in the Local Group Standard of Rest lie between -100 and +40 km s-1, comparable to the systemic velocities of M31 and M33. The clouds appear to be isolated kinematically and spatially from each other. The total H i mass of all nine clouds is 1.4 × 106M⊙ for an adopted distance of 800 kpc, with perhaps another 0.2 × 106M⊙ in smaller clouds or more diffuse emission. The H i mass of each cloud is typically three orders of magnitude less than the dynamical (virial) mass needed to bind the cloud gravitationally. Although they have the size and H i mass of dwarf galaxies, the clouds are unlikely to be part of the satellite system of the Local Group, as they lack stars. To the north of M31, sensitive H i measurements on a coarse grid find emission that may be associated with an extension of the M31 high-velocity cloud (HVC) population to projected distances of ˜100 kpc. An extension of the M31 HVC population at a similar distance to the southeast, toward M33, is not observed.

  12. Reionization on large scales. IV. Predictions for the 21 cm signal incorporating the light cone effect

    SciTech Connect

    La Plante, P.; Battaglia, N.; Natarajan, A.; Peterson, J. B.; Trac, H.; Cen, R.; Loeb, A.

    2014-07-01

    We present predictions for the 21 cm brightness temperature power spectrum during the Epoch of Reionization (EoR). We discuss the implications of the 'light cone' effect, which incorporates evolution of the neutral hydrogen fraction and 21 cm brightness temperature along the line of sight. Using a novel method calibrated against radiation-hydrodynamic simulations, we model the neutral hydrogen density field and 21 cm signal in large volumes (L = 2 Gpc h {sup –1}). The inclusion of the light cone effect leads to a relative decrease of about 50% in the 21 cm power spectrum on all scales. We also find that the effect is more prominent at the midpoint of reionization and later. The light cone effect can also introduce an anisotropy along the line of sight. By decomposing the 3D power spectrum into components perpendicular to and along the line of sight, we find that in our fiducial reionization model, there is no significant anisotropy. However, parallel modes can contribute up to 40% more power for shorter reionization scenarios. The scales on which the light cone effect is relevant are comparable to scales where one measures the baryon acoustic oscillation. We argue that due to its large comoving scale and introduction of anisotropy, the light cone effect is important when considering redshift space distortions and future application to the Alcock-Paczyński test for the determination of cosmological parameters.

  13. Chromatic effects in the 21 cm global signal from the cosmic dawn

    NASA Astrophysics Data System (ADS)

    Vedantham, H. K.; Koopmans, L. V. E.; de Bruyn, A. G.; Wijnholds, S. J.; Ciardi, B.; Brentjens, M. A.

    2014-01-01

    The redshifted 21 cm brightness distribution from neutral hydrogen is a promising probe into the cosmic dark ages, cosmic dawn and re-ionization. Low Frequency Array's (LOFAR) Low Band Antennas (LBA) may be used in the frequency range 45 to 85 MHz (30 > z > 16) to measure the sky-averaged redshifted 21 cm brightness temperature as a function of frequency, or equivalently, cosmic redshift. These low frequencies are affected by strong Galactic foreground emission that is observed through frequency-dependent ionospheric and antenna beam distortions which lead to chromatic mixing of spatial structure into spectral structure. Using simple models, we show that (i) the additional antenna temperature due to ionospheric refraction and absorption are at an ˜1 per cent level - two-to-three orders of magnitude higher than the expected 21 cm signal, and have an approximate ν-2 dependence, (ii) ionospheric refraction leads to a knee-like modulation on the sky spectrum at ν ≈ 4 times plasma frequency. Using more realistic simulations, we show that in the measured sky spectrum, more than 50 per cent of the 21 cm signal variance can be lost to confusion from foregrounds and chromatic effects. To mitigate this confusion, we recommend modelling of chromatic effects using additional priors and interferometric visibilities rather than subtracting them as generic functions of frequency as previously proposed.

  14. Modelling the cosmic neutral hydrogen from DLAs and 21-cm observations

    NASA Astrophysics Data System (ADS)

    Padmanabhan, Hamsa; Choudhury, T. Roy; Refregier, Alexandre

    2016-05-01

    We review the analytical prescriptions in the literature to model the 21-cm (emission line surveys/intensity mapping experiments) and Damped Lyman-Alpha (DLA) observations of neutral hydrogen (H I) in the post-reionization universe. While these two sets of prescriptions have typically been applied separately for the two probes, we attempt to connect these approaches to explore the consequences for the distribution and evolution of H I across redshifts. We find that a physically motivated, 21-cm-based prescription, extended to account for the DLA observables provides a good fit to the majority of the available data, but cannot accommodate the recent measurement of the clustering of DLAs at z ˜ 2.3. This highlights a tension between the DLA bias and the 21-cm measurements, unless there is a very significant change in the nature of H I-bearing systems across redshifts 0-3. We discuss the implications of our findings for the characteristic host halo masses of the DLAs and the power spectrum of 21-cm intensity fluctuations.

  15. A FOURTH H I 21 cm ABSORPTION SYSTEM IN THE SIGHT LINE OF MG J0414+0534: A RECORD FOR INTERVENING ABSORBERS

    SciTech Connect

    Tanna, A.; Webb, J. K.; Curran, S. J.; Whiting, M. T.; Bignell, C.

    2013-08-01

    We report the detection of a strong H I 21 cm absorption system at z = 0.5344, as well as a candidate system at z = 0.3389, in the sight line toward the z = 2.64 quasar MG J0414+0534. This, in addition to the absorption at the host redshift and the other two intervening absorbers, takes the total to four (possibly five). The previous maximum number of 21 cm absorbers detected along a single sight line is two and so we suspect that this number of gas-rich absorbers is in some way related to the very red color of the background source. Despite this, no molecular gas (through OH absorption) has yet been detected at any of the 21 cm redshifts, although, from the population of 21 cm absorbers as a whole, there is evidence for a weak correlation between the atomic line strength and the optical-near-infrared color. In either case, the fact that so many gas-rich galaxies (likely to be damped Ly{alpha} absorption systems) have been found along a single sight line toward a highly obscured source may have far-reaching implications for the population of faint galaxies not detected in optical surveys, a possibility which could be addressed through future wide-field absorption line surveys with the Square Kilometer Array.

  16. FOREGROUND MODEL AND ANTENNA CALIBRATION ERRORS IN THE MEASUREMENT OF THE SKY-AVERAGED λ21 cm SIGNAL AT z∼ 20

    SciTech Connect

    Bernardi, G.; McQuinn, M.; Greenhill, L. J.

    2015-01-20

    The most promising near-term observable of the cosmic dark age prior to widespread reionization (z ∼ 15-200) is the sky-averaged λ21 cm background arising from hydrogen in the intergalactic medium. Though an individual antenna could in principle detect the line signature, data analysis must separate foregrounds that are orders of magnitude brighter than the λ21 cm background (but that are anticipated to vary monotonically and gradually with frequency, e.g., they are considered {sup s}pectrally smooth{sup )}. Using more physically motivated models for foregrounds than in previous studies, we show that the intrinsic spectral smoothness of the foregrounds is likely not a concern, and that data analysis for an ideal antenna should be able to detect the λ21 cm signal after subtracting a ∼fifth-order polynomial in log ν. However, we find that the foreground signal is corrupted by the angular and frequency-dependent response of a real antenna. The frequency dependence complicates modeling of foregrounds commonly based on the assumption of spectral smoothness. Our calculations focus on the Large-aperture Experiment to detect the Dark Age, which combines both radiometric and interferometric measurements. We show that statistical uncertainty remaining after fitting antenna gain patterns to interferometric measurements is not anticipated to compromise extraction of the λ21 cm signal for a range of cosmological models after fitting a seventh-order polynomial to radiometric data. Our results generalize to most efforts to measure the sky-averaged spectrum.

  17. Light-cone anisotropy in the 21 cm signal from the epoch of reionization

    NASA Astrophysics Data System (ADS)

    Zawada, Karolina; Semelin, Benoît; Vonlanthen, Patrick; Baek, Sunghye; Revaz, Yves

    2014-04-01

    Using a suite of detailed numerical simulations, we estimate the level of anisotropy generated by the time evolution along the light cone of the 21 cm signal from the epoch of reionization. Our simulations include the physics necessary to model the signal during both the late emission regime and the early absorption regime, namely X-ray and Lyman band 3D radiative transfer in addition to the usual dynamics and ionizing UV transfer. The signal is analysed using correlation functions perpendicular and parallel to the line of sight. We reproduce general findings from previous theoretical studies: the overall amplitude of the correlations and the fact that the light-cone anisotropy is visible only on large scales (100 comoving Mpc). However, the detailed behaviour is different. We find that, at three different epochs, the amplitudes of the correlations along and perpendicular to the line of sight differ from each other, indicating anisotropy. We show that these three epochs are associated with three events of the global reionization history: the overlap of ionized bubbles, the onset of mild heating by X-rays in regions around the sources, and the onset of efficient Lyman α coupling in regions around the sources. We find that a 20 × 20 deg2 survey area may be necessary to mitigate sample variance when we use the directional correlation functions. On a 100 Mpc (comoving) scale, we show that the light-cone anisotropy dominates over the anisotropy generated by peculiar velocity gradients computed in the linear regime. By modelling instrumental noise and limited resolution, we find that the anisotropy should be easily detectable by the Square Kilometre Array, assuming perfect foreground removal, the limiting factor being a large enough survey size. In the case of the Low-Frequency Array for radio astronomy, it is likely that only one anisotropy episode (ionized bubble overlap) will fall in the observing frequency range. This episode will be detectable only if sample

  18. High-accuracy linear and circular polarization measurements at 21 cm

    NASA Technical Reports Server (NTRS)

    De Pater, I.; Weiler, K. W.

    1982-01-01

    New high-accuracy linear and circular polarization measurements have been obtained for 27 small-diameter radio sources, using the Westerbork Synthesis Radio Telescope at 21 cm (1415 MHz). From these and other observed properties of the sources, estimates of the average internal magnetic field strengths in the sources are made by applying the uniform synchrotron emission model to the measured circular polarization and by using equipartition arguments. These two values are compared and found to be in agreement to within an order of magnitude, as was previously found by Weiler and de Pater (1980). Also, the magnetic fields estimated from circular polarization measurements at two different wavelengths (49 and 21 cm) are compared and found to be in rough agreement, but with indications of differences between variable and nonvariable sources. A comparison of the magnitudes of linear and circular polarization in sources shows no correlations.

  19. Cosmologically probing ultra-light particle dark matter using 21 cm signals

    SciTech Connect

    Kadota, Kenji; Mao, Yi; Silk, Joseph; Ichiki, Kiyomoto E-mail: mao@iap.fr E-mail: j.silk1@physics.ox.ac.uk

    2014-06-01

    There can arise ubiquitous ultra-light scalar fields in the Universe, such as the pseudo-Goldstone bosons from the spontaneous breaking of an approximate symmetry, which can make a partial contribution to the dark matter and affect the large scale structure of the Universe. While the properties of those ultra-light dark matter are heavily model dependent and can vary in a wide range, we develop a model-independent analysis to forecast the constraints on their mass and abundance using futuristic but realistic 21 cm observables as well as CMB fluctuations, including CMB lensing measurements. Avoiding the highly nonlinear regime, the 21 cm emission line spectra are most sensitive to the ultra-light dark matter with mass m ∼ 10{sup −26} eV for which the precision attainable on mass and abundance bounds can be of order of a few percent.

  20. The imprint of the cosmic supermassive black hole growth history on the 21 cm background radiation

    NASA Astrophysics Data System (ADS)

    Tanaka, Takamitsu L.; O'Leary, Ryan M.; Perna, Rosalba

    2016-01-01

    The redshifted 21 cm transition line of hydrogen tracks the thermal evolution of the neutral intergalactic medium (IGM) at `cosmic dawn', during the emergence of the first luminous astrophysical objects (˜100 Myr after the big bang) but before these objects ionized the IGM (˜400-800 Myr after the big bang). Because X-rays, in particular, are likely to be the chief energy courier for heating the IGM, measurements of the 21 cm signature can be used to infer knowledge about the first astrophysical X-ray sources. Using analytic arguments and a numerical population synthesis algorithm, we argue that the progenitors of supermassive black holes (SMBHs) should be the dominant source of hard astrophysical X-rays - and thus the primary driver of IGM heating and the 21 cm signature - at redshifts z ≳ 20, if (i) they grow readily from the remnants of Population III stars and (ii) produce X-rays in quantities comparable to what is observed from active galactic nuclei and high-mass X-ray binaries. We show that models satisfying these assumptions dominate over contributions to IGM heating from stellar populations, and cause the 21 cm brightness temperature to rise at z ≳ 20. An absence of such a signature in the forthcoming observational data would imply that SMBH formation occurred later (e.g. via so-called direct collapse scenarios), that it was not a common occurrence in early galaxies and protogalaxies, or that it produced far fewer X-rays than empirical trends at lower redshifts, either due to intrinsic dimness (radiative inefficiency) or Compton-thick obscuration close to the source.

  1. Cosmic reionization on computers. Mean and fluctuating redshifted 21 CM signal

    DOE PAGES

    Kaurov, Alexander A.; Gnedin, Nickolay Y.

    2016-06-20

    We explore the mean and fluctuating redshifted 21 cm signal in numerical simulations from the Cosmic Reionization On Computers project. We find that the mean signal varies between about ±25 mK. Most significantly, we find that the negative pre-reionization dip at z ~ 10–15 only extends tomore » $$\\langle {\\rm{\\Delta }}{T}_{B}\\rangle \\sim -25\\,{\\rm{mK}}$$, requiring substantially higher sensitivity from global signal experiments that operate in this redshift range (EDGES-II, LEDA, SCI-HI, and DARE) than has often been assumed previously. We also explore the role of dense substructure (filaments and embedded galaxies) in the formation of the 21 cm power spectrum. We find that by neglecting the semi-neutral substructure inside ionized bubbles, the power spectrum can be misestimated by 25%–50% at scales k ~ 0.1–1h Mpc–1. Furthermore, this scale range is of particular interest, because the upcoming 21 cm experiments (Murchison Widefield Array, Precision Array for Probing the Epoch of Reionization, Hydrogen Epoch of Reionization Array) are expected to be most sensitive within it.« less

  2. Prospects of probing quintessence with HI 21-cm intensity mapping survey

    NASA Astrophysics Data System (ADS)

    Hussain, Azam; Thakur, Shruti; Sarkar, Tapomoy Guha; Sen, Anjan A.

    2016-09-01

    We investigate the prospect of constraining scalar field dark energy models using HI 21-cm intensity mapping surveys. We consider a wide class of coupled scalar field dark energy models whose predictions about the background cosmological evolution are different from the ΛCDM predictions by a few percent. We find that these models can be statistically distinguished from ΛCDM through their imprint on the 21-cm angular power spectrum. At the fiducial z = 1.5, corresponding to a radio interferometric observation of the post-reionization HI 21 cm observation at frequency 568 MHz, these models can infact be distinguished from the ΛCDM model at SNR > 3σ level using a 10,000 hr radio observation distributed over 40 pointings of a SKA1-mid like radio-telescope. We also show that tracker models are more likely to be ruled out in comparison with ΛCDM than the thawer models. Future radio observations can be instrumental in obtaining tighter constraints on the parameter space of dark energy models and supplement the bounds obtained from background studies.

  3. Cosmic Reionization On Computers. Mean and Fluctuating Redshifted 21 cm Signal

    NASA Astrophysics Data System (ADS)

    Kaurov, Alexander A.; Gnedin, Nickolay Y.

    2016-06-01

    We explore the mean and fluctuating redshifted 21 cm signal in numerical simulations from the Cosmic Reionization On Computers project. We find that the mean signal varies between about ±25 mK. Most significantly, we find that the negative pre-reionization dip at z ˜ 10–15 only extends to < {{Δ }}{T}B> ˜ -25 {{mK}}, requiring substantially higher sensitivity from global signal experiments that operate in this redshift range (EDGES-II, LEDA, SCI-HI, and DARE) than has often been assumed previously. We also explore the role of dense substructure (filaments and embedded galaxies) in the formation of the 21 cm power spectrum. We find that by neglecting the semi-neutral substructure inside ionized bubbles, the power spectrum can be misestimated by 25%–50% at scales k ˜ 0.1–1h Mpc‑1. This scale range is of particular interest, because the upcoming 21 cm experiments (Murchison Widefield Array, Precision Array for Probing the Epoch of Reionization, Hydrogen Epoch of Reionization Array) are expected to be most sensitive within it.

  4. OPENING THE 21 cm EPOCH OF REIONIZATION WINDOW: MEASUREMENTS OF FOREGROUND ISOLATION WITH PAPER

    SciTech Connect

    Pober, Jonathan C.; Parsons, Aaron R.; Ali, Zaki; Aguirre, James E.; Moore, David F.; Bradley, Richard F.; Carilli, Chris L.; DeBoer, Dave; Dexter, Matthew; MacMahon, Dave; Gugliucci, Nicole E.; Jacobs, Daniel C.; Klima, Patricia J.; Manley, Jason; Walbrugh, William P.; Stefan, Irina I.

    2013-05-10

    We present new observations with the Precision Array for Probing the Epoch of Reionization with the aim of measuring the properties of foreground emission for 21 cm epoch of reionization (EoR) experiments at 150 MHz. We focus on the footprint of the foregrounds in cosmological Fourier space to understand which modes of the 21 cm power spectrum will most likely be compromised by foreground emission. These observations confirm predictions that foregrounds can be isolated to a {sup w}edge{sup -}like region of two-dimensional (k , k{sub Parallel-To })-space, creating a window for cosmological studies at higher k{sub Parallel-To} values. We also find that the emission extends past the nominal edge of this wedge due to spectral structure in the foregrounds, with this feature most prominent on the shortest baselines. Finally, we filter the data to retain only this ''unsmooth'' emission and image its specific k{sub Parallel-To} modes. The resultant images show an excess of power at the lowest modes, but no emission can be clearly localized to any one region of the sky. This image is highly suggestive that the most problematic foregrounds for 21 cm EoR studies will not be easily identifiable bright sources, but rather an aggregate of fainter emission.

  5. A Bayesian analysis of redshifted 21-cm H I signal and foregrounds: simulations for LOFAR

    NASA Astrophysics Data System (ADS)

    Ghosh, Abhik; Koopmans, Léon V. E.; Chapman, E.; Jelić, V.

    2015-09-01

    Observations of the epoch of reionization (EoR) using the 21-cm hyperfine emission of neutral hydrogen (H I) promise to open an entirely new window on the formation of the first stars, galaxies and accreting black holes. In order to characterize the weak 21-cm signal, we need to develop imaging techniques that can reconstruct the extended emission very precisely. Here, we present an inversion technique for LOw Frequency ARray (LOFAR) baselines at the North Celestial Pole (NCP), based on a Bayesian formalism with optimal spatial regularization, which is used to reconstruct the diffuse foreground map directly from the simulated visibility data. We notice that the spatial regularization de-noises the images to a large extent, allowing one to recover the 21-cm power spectrum over a considerable k⊥-k∥ space in the range 0.03 Mpc-1 < k⊥ < 0.19 Mpc-1 and 0.14 Mpc-1 < k∥ < 0.35 Mpc-1 without subtracting the noise power spectrum. We find that, in combination with using generalized morphological component analysis (GMCA), a non-parametric foreground removal technique, we can mostly recover the spherical average power spectrum within 2σ statistical fluctuations for an input Gaussian random root-mean-square noise level of 60 mK in the maps after 600 h of integration over a 10-MHz bandwidth.

  6. What next-generation 21 cm power spectrum measurements can teach us about the epoch of reionization

    SciTech Connect

    Pober, Jonathan C.; Morales, Miguel F.; Liu, Adrian; McQuinn, Matthew; Parsons, Aaron R.; Dillon, Joshua S.; Hewitt, Jacqueline N.; Tegmark, Max; Aguirre, James E.; Bowman, Judd D.; Jacobs, Daniel C.; Bradley, Richard F.; Carilli, Chris L.; DeBoer, David R.; Werthimer, Dan J.

    2014-02-20

    A number of experiments are currently working toward a measurement of the 21 cm signal from the epoch of reionization (EoR). Whether or not these experiments deliver a detection of cosmological emission, their limited sensitivity will prevent them from providing detailed information about the astrophysics of reionization. In this work, we consider what types of measurements will be enabled by the next generation of larger 21 cm EoR telescopes. To calculate the type of constraints that will be possible with such arrays, we use simple models for the instrument, foreground emission, and the reionization history. We focus primarily on an instrument modeled after the ∼0.1 km{sup 2} collecting area Hydrogen Epoch of Reionization Array concept design and parameterize the uncertainties with regard to foreground emission by considering different limits to the recently described 'wedge' footprint in k space. Uncertainties in the reionization history are accounted for using a series of simulations that vary the ionizing efficiency and minimum virial temperature of the galaxies responsible for reionization, as well as the mean free path of ionizing photons through the intergalactic medium. Given various combinations of models, we consider the significance of the possible power spectrum detections, the ability to trace the power spectrum evolution versus redshift, the detectability of salient power spectrum features, and the achievable level of quantitative constraints on astrophysical parameters. Ultimately, we find that 0.1 km{sup 2} of collecting area is enough to ensure a very high significance (≳ 30σ) detection of the reionization power spectrum in even the most pessimistic scenarios. This sensitivity should allow for meaningful constraints on the reionization history and astrophysical parameters, especially if foreground subtraction techniques can be improved and successfully implemented.

  7. Cosmology on ultralarge scales with intensity mapping of the neutral hydrogen 21 cm emission: limits on primordial non-Gaussianity.

    PubMed

    Camera, Stefano; Santos, Mário G; Ferreira, Pedro G; Ferramacho, Luís

    2013-10-25

    The large-scale structure of the Universe supplies crucial information about the physical processes at play at early times. Unresolved maps of the intensity of 21 cm emission from neutral hydrogen HI at redshifts z=/~1-5 are the best hope of accessing the ultralarge-scale information, directly related to the early Universe. A purpose-built HI intensity experiment may be used to detect the large scale effects of primordial non-Gaussianity, placing stringent bounds on different models of inflation. We argue that it may be possible to place tight constraints on the non-Gaussianity parameter f(NL), with an error close to σ(f(NL))~1.

  8. Statistics of the epoch of reionization 21-cm signal - I. Power spectrum error-covariance

    NASA Astrophysics Data System (ADS)

    Mondal, Rajesh; Bharadwaj, Somnath; Majumdar, Suman

    2016-02-01

    The non-Gaussian nature of the epoch of reionization (EoR) 21-cm signal has a significant impact on the error variance of its power spectrum P(k). We have used a large ensemble of seminumerical simulations and an analytical model to estimate the effect of this non-Gaussianity on the entire error-covariance matrix {C}ij. Our analytical model shows that {C}ij has contributions from two sources. One is the usual variance for a Gaussian random field which scales inversely of the number of modes that goes into the estimation of P(k). The other is the trispectrum of the signal. Using the simulated 21-cm Signal Ensemble, an ensemble of the Randomized Signal and Ensembles of Gaussian Random Ensembles we have quantified the effect of the trispectrum on the error variance {C}ii. We find that its relative contribution is comparable to or larger than that of the Gaussian term for the k range 0.3 ≤ k ≤ 1.0 Mpc-1, and can be even ˜200 times larger at k ˜ 5 Mpc-1. We also establish that the off-diagonal terms of {C}ij have statistically significant non-zero values which arise purely from the trispectrum. This further signifies that the error in different k modes are not independent. We find a strong correlation between the errors at large k values (≥0.5 Mpc-1), and a weak correlation between the smallest and largest k values. There is also a small anticorrelation between the errors in the smallest and intermediate k values. These results are relevant for the k range that will be probed by the current and upcoming EoR 21-cm experiments.

  9. Extracting Physical Parameters for the First Galaxies from the Cosmic Dawn Global 21-cm Spectrum

    NASA Astrophysics Data System (ADS)

    Burns, Jack O.; Mirocha, Jordan; harker, geraint; Tauscher, Keith; Datta, Abhirup

    2016-01-01

    The all-sky or global redshifted 21-cm HI signal is a potentially powerful probe of the first luminous objects and their environs during the transition from the Dark Ages to Cosmic Dawn (35 > z > 6). The first stars, black holes, and galaxies heat and ionize the surrounding intergalactic medium, composed mainly of neutral hydrogen, so the hyperfine 21-cm transition can be used to indirectly study these early radiation sources. The properties of these objects can be examined via the broad absorption and emission features that are expected in the spectrum. The Dark Ages Radio Explorer (DARE) is proposed to conduct these observations at low radio astronomy frequencies, 40-120 MHz, in a 125 km orbit about the Moon. The Moon occults both the Earth and the Sun as DARE makes observations above the lunar farside, thus eliminating the corrupting effects from Earth's ionosphere, radio frequency interference, and solar nanoflares. The signal is extracted from the galactic/extragalactic foreground employing Bayesian methods, including Markov Chain Monte Carlo (MCMC) techniques. Theory indicates that the 21-cm signal is well described by a model in which the evolution of various physical quantities follows a hyperbolic tangent (tanh) function of redshift. We show that this approach accurately captures degeneracies and covariances between parameters, including those related to the signal, foreground, and the instrument. Furthermore, we also demonstrate that MCMC fits will set meaningful constraints on the Ly-α, ionizing, and X-ray backgrounds along with the minimum virial temperature of the first star-forming halos.

  10. 21CMMC: an MCMC analysis tool enabling astrophysical parameter studies of the cosmic 21 cm signal

    NASA Astrophysics Data System (ADS)

    Greig, Bradley; Mesinger, Andrei

    2015-06-01

    We introduce 21 CMMC: a parallelized, Monte Carlo Markov Chain analysis tool, incorporating the epoch of reionization (EoR) seminumerical simulation 21 CMFAST. 21 CMMC estimates astrophysical parameter constraints from 21 cm EoR experiments, accommodating a variety of EoR models, as well as priors on model parameters and the reionization history. To illustrate its utility, we consider two different EoR scenarios, one with a single population of galaxies (with a mass-independent ionizing efficiency) and a second, more general model with two different, feedback-regulated populations (each with mass-dependent ionizing efficiencies). As an example, combining three observations (z = 8, 9 and 10) of the 21 cm power spectrum with a conservative noise estimate and uniform model priors, we find that interferometers with specifications like the Low Frequency Array/Hydrogen Epoch of Reionization Array (HERA)/Square Kilometre Array 1 (SKA1) can constrain common reionization parameters: the ionizing efficiency (or similarly the escape fraction), the mean free path of ionizing photons and the log of the minimum virial temperature of star-forming haloes to within 45.3/22.0/16.7, 33.5/18.4/17.8 and 6.3/3.3/2.4 per cent, ˜1σ fractional uncertainty, respectively. Instead, if we optimistically assume that we can perfectly characterize the EoR modelling uncertainties, we can improve on these constraints by up to a factor of ˜few. Similarly, the fractional uncertainty on the average neutral fraction can be constrained to within ≲ 10 per cent for HERA and SKA1. By studying the resulting impact on astrophysical constraints, 21 CMMC can be used to optimize (i) interferometer designs; (ii) foreground cleaning algorithms; (iii) observing strategies; (iv) alternative statistics characterizing the 21 cm signal; and (v) synergies with other observational programs.

  11. 21-cm lensing and the cold spot in the cosmic microwave background.

    PubMed

    Kovetz, Ely D; Kamionkowski, Marc

    2013-04-26

    An extremely large void and a cosmic texture are two possible explanations for the cold spot seen in the cosmic microwave background. We investigate how well these two hypotheses can be tested with weak lensing of 21-cm fluctuations from the epoch of reionization measured with the Square Kilometer Array. While the void explanation for the cold spot can be tested with Square Kilometer Array, given enough observation time, the texture scenario requires significantly prolonged observations, at the highest frequencies that correspond to the epoch of reionization, over the field of view containing the cold spot. PMID:23679703

  12. The 21-cm BAO signature of enriched low-mass galaxies during cosmic reionization

    NASA Astrophysics Data System (ADS)

    Cohen, Aviad; Fialkov, Anastasia; Barkana, Rennan

    2016-06-01

    Studies of the formation of the first stars have established that they formed in small haloes of ˜105-106 M⊙ via molecular hydrogen cooling. Since a low level of ultraviolet radiation from stars suffices to dissociate molecular hydrogen, under the usually assumed scenario this primordial mode of star formation ended by redshift z ˜ 15 and much more massive haloes came to dominate star formation. However, metal enrichment from the first stars may have allowed the smaller haloes to continue to form stars. In this Letter, we explore the possible effect of star formation in metal-rich low-mass haloes on the redshifted 21-cm signal of neutral hydrogen from z = 6 to 40. These haloes are significantly affected by the supersonic streaming velocity, with its characteristic baryon acoustic oscillation (BAO) signature. Thus, enrichment of low-mass galaxies can produce a strong signature in the 21-cm power spectrum over a wide range of redshifts, especially if star formation in the small haloes was more efficient than suggested by current simulations. We show that upcoming radio telescopes can easily distinguish among various possible scenarios.

  13. Violation of statistical isotropy and homogeneity in the 21-cm power spectrum

    NASA Astrophysics Data System (ADS)

    Shiraishi, Maresuke; Muñoz, Julian B.; Kamionkowski, Marc; Raccanelli, Alvise

    2016-05-01

    Most inflationary models predict primordial perturbations to be statistically isotropic and homogeneous. Cosmic microwave background (CMB) observations, however, indicate a possible departure from statistical isotropy in the form of a dipolar power modulation at large angular scales. Alternative models of inflation, beyond the simplest single-field slow-roll models, can generate a small power asymmetry, consistent with these observations. Observations of clustering of quasars show, however, agreement with statistical isotropy at much smaller angular scales. Here, we propose to use off-diagonal components of the angular power spectrum of the 21-cm fluctuations during the dark ages to test this power asymmetry. We forecast results for the planned SKA radio array, a future radio array, and the cosmic-variance-limited case as a theoretical proof of principle. Our results show that the 21-cm line power spectrum will enable access to information at very small scales and at different redshift slices, thus improving upon the current CMB constraints by ˜2 orders of magnitude for a dipolar asymmetry and by ˜1 - 3 orders of magnitude for a quadrupolar asymmetry case.

  14. Effects of the sources of reionization on 21-cm redshift-space distortions

    NASA Astrophysics Data System (ADS)

    Majumdar, Suman; Jensen, Hannes; Mellema, Garrelt; Chapman, Emma; Abdalla, Filipe B.; Lee, Kai-Yan; Iliev, Ilian T.; Dixon, Keri L.; Datta, Kanan K.; Ciardi, Benedetta; Fernandez, Elizabeth R.; Jelić, Vibor; Koopmans, Léon V. E.; Zaroubi, Saleem

    2016-02-01

    The observed 21 cm signal from the epoch of reionization will be distorted along the line of sight by the peculiar velocities of matter particles. These redshift-space distortions will affect the contrast in the signal and will also make it anisotropic. This anisotropy contains information about the cross-correlation between the matter density field and the neutral hydrogen field, and could thus potentially be used to extract information about the sources of reionization. In this paper, we study a collection of simulated reionization scenarios assuming different models for the sources of reionization. We show that the 21 cm anisotropy is best measured by the quadrupole moment of the power spectrum. We find that, unless the properties of the reionization sources are extreme in some way, the quadrupole moment evolves very predictably as a function of global neutral fraction. This predictability implies that redshift-space distortions are not a very sensitive tool for distinguishing between reionization sources. However, the quadrupole moment can be used as a model-independent probe for constraining the reionization history. We show that such measurements can be done to some extent by first-generation instruments such as LOFAR, while the SKA should be able to measure the reionization history using the quadrupole moment of the power spectrum to great accuracy.

  15. Limits on variations in fundamental constants from 21-cm and ultraviolet Quasar absorption lines.

    PubMed

    Tzanavaris, P; Webb, J K; Murphy, M T; Flambaum, V V; Curran, S J

    2005-07-22

    Quasar absorption spectra at 21-cm and UV rest wavelengths are used to estimate the time variation of x [triple-bond] alpha(2)g(p)mu, where alpha is the fine structure constant, g(p) the proton g factor, and m(e)/m(p) [triple-bond] mu the electron/proton mass ratio. Over a redshift range 0.24 < or = zeta(abs) < or = 2.04, (Deltax/x)(weighted)(total) = (1.17 +/- 1.01) x 10(-5). A linear fit gives x/x = (-1.43 +/- 1.27) x 10(-15) yr(-1). Two previous results on varying alpha yield the strong limits Deltamu/mu = (2.31 +/- 1.03) x 10(-5) and Deltamu/mu=(1.29 +/- 1.01) x10(-5). Our sample, 8 x larger than any previous, provides the first direct estimate of the intrinsic 21-cm and UV velocity differences 6 km s(-1).

  16. Tracing the Milky Way Nuclear Wind with 21cm Atomic Hydrogen Emission

    NASA Astrophysics Data System (ADS)

    Lockman, Felix J.; McClure-Griffiths, N. M.

    2016-08-01

    There is evidence in 21 cm H i emission for voids several kiloparsecs in size centered approximately on the Galactic center, both above and below the Galactic plane. These appear to map the boundaries of the Galactic nuclear wind. An analysis of H i at the tangent points, where the distance to the gas can be estimated with reasonable accuracy, shows a sharp transition at Galactic radii R ≲ 2.4 kpc from the extended neutral gas layer characteristic of much of the Galactic disk, to a thin Gaussian layer with FWHM ˜ 125 pc. An anti-correlation between H i and γ-ray emission at latitudes 10^\\circ ≤slant | b| ≤slant 20^\\circ suggests that the boundary of the extended H i layer marks the walls of the Fermi Bubbles. With H i, we are able to trace the edges of the voids from | z| \\gt 2 {{kpc}} down to z ≈ 0, where they have a radius ˜2 kpc. The extended Hi layer likely results from star formation in the disk, which is limited largely to R ≳ 3 kpc, so the wind may be expanding into an area of relatively little H i. Because the H i kinematics can discriminate between gas in the Galactic center and foreground material, 21 cm H i emission may be the best probe of the extent of the nuclear wind near the Galactic plane.

  17. MEASUREMENT OF 21 cm BRIGHTNESS FLUCTUATIONS AT z {approx} 0.8 IN CROSS-CORRELATION

    SciTech Connect

    Masui, K. W.; Switzer, E. R.; Calin, L.-M.; Pen, U.-L.; Shaw, J. R.; Banavar, N.; Bandura, K.; Blake, C.; Chang, T.-C.; Liao, Y.-W.; Chen, X.; Li, Y.-C.; Natarajan, A.; Peterson, J. B.; Voytek, T. C.

    2013-01-20

    In this Letter, 21 cm intensity maps acquired at the Green Bank Telescope are cross-correlated with large-scale structure traced by galaxies in the WiggleZ Dark Energy Survey. The data span the redshift range 0.6 < z < 1 over two fields totaling {approx}41 deg. sq. and 190 hr of radio integration time. The cross-correlation constrains {Omega}{sub HI} b{sub HI} r = [0.43 {+-} 0.07(stat.) {+-} 0.04(sys.)] Multiplication-Sign 10{sup -3}, where {Omega}{sub HI} is the neutral hydrogen (H I) fraction, r is the galaxy-hydrogen correlation coefficient, and b{sub HI} is the H I bias parameter. This is the most precise constraint on neutral hydrogen density fluctuations in a challenging redshift range. Our measurement improves the previous 21 cm cross-correlation at z {approx} 0.8 both in its precision and in the range of scales probed.

  18. Cosmological signatures of tilted isocurvature perturbations: reionization and 21cm fluctuations

    SciTech Connect

    Sekiguchi, Toyokazu; Sugiyama, Naoshi; Tashiro, Hiroyuki; Silk, Joseph E-mail: hiroyuki.tashiro@asu.edu E-mail: naoshi@nagoya-u.jp

    2014-03-01

    We investigate cosmological signatures of uncorrelated isocurvature perturbations whose power spectrum is blue-tilted with spectral index 2∼21cm line fluctuations due to neutral hydrogens in minihalos. Combination of measurements of the reionization optical depth and 21cm line fluctuations will provide complementary probes of a highly blue-tilted isocurvature power spectrum.

  19. Strong RFI observed in protected 21 cm band at Zurich observatory, Switzerland

    NASA Astrophysics Data System (ADS)

    Monstein, C.

    2014-03-01

    While testing a new antenna control software tool, the telescope was moved to the most western azimuth position pointing to our own building. While de-accelerating the telescope, the spectrometer showed strong broadband radio frequency interference (RFI) and two single-frequency carriers around 1412 and 1425 MHz, both of which are in the internationally protected band. After lengthy analysis it was found out, that the Webcam AXIS2000 was the source for both the broadband and single-frequency interference. Switching off the Webcam solved the problem immediately. So, for future observations of 21 cm radiation, all nearby electronics has to be switched off. Not only the Webcam but also all unused PCs, printers, networks, monitors etc.

  20. The 21 cm signature of shock heated and diffuse cosmic string wakes

    SciTech Connect

    Hernández, Oscar F.; Brandenberger, Robert H. E-mail: rhb@physics.mcgill.ca

    2012-07-01

    The analysis of the 21 cm signature of cosmic string wakes is extended in several ways. First we consider the constraints on Gμ from the absorption signal of shock heated wakes laid down much later than matter radiation equality. Secondly we analyze the signal of diffuse wake, that is those wakes in which there is a baryon overdensity but which have not shock heated. Finally we compare the size of these signals to the expected thermal noise per pixel which dominates over the background cosmic gas brightness temperature and find that the cosmic string signal will exceed the thermal noise of an individual pixel in the Square Kilometre Array for string tensions Gμ > 2.5 × 10{sup −8}.

  1. VizieR Online Data Catalog: Galactic 21-cm line Survey (Westerhout+ 1982)

    NASA Astrophysics Data System (ADS)

    Westerhout, G.; Wendlandt, H. U.

    1997-06-01

    This catalog presents a completely sampled survey of 21-cm line profiles extending from Galactic longitude 11 to 235 degrees and nominally covering a range between latitude +2 and -2 degrees. It was observed in 1971-72 with the newly resurfaced 92-m (300-foot) telescope of the National Radio Astronomy Observatory (NRAO) in Green Bank, W.V. The spatial resolution is 0.22 degrees (13 arcmin), and the velocity resolution is 2 km/s. The line profiles have 260 values of Brightness Temperature at 1 km/s intervals, and at spacings of 0.1 degree in longitude and 0.1 degree in latitude. The r.m.s per data point varies from 1.0K at low declinations to 0.5K at high declinations. The maps at constant Galactic longitude published in the printed version are at intervals of 0.2 degrees in longitude; the spectra in this catalog are therefore spatially twice as dense. The catalog is arranged in two forms: as FITS data cubes, and as FITS binary tables. The cubes contain three-dimensional arrays of spectra for various longitude ranges. The binary tables contain spectra at constant Galactic latitude, along with coordinate and velocity information necessary for the interpretation of individual spectra. A detailed description of the telescope beam characteristics and the derivation of the temperature scale is given by Westerhout, G., Mader, G.L., and Harten, R.H. (Astron. and Astrophys. Suppl. 49, 137-141, 1982). Temperature scales of this and several other 21-cm line surveys were compared by Harten, R.H., Westerhout, G., and Kerr, F.J. (Astron.J. 80, 307-310, 1975) and found to agree to within 5 %. (1 data file).

  2. Warm dark matter signatures on the 21cm power spectrum: intensity mapping forecasts for SKA

    SciTech Connect

    Carucci, Isabella P.; Villaescusa-Navarro, Francisco; Viel, Matteo; Lapi, Andrea E-mail: villaescusa@oats.inaf.it E-mail: lapi@sissa.it

    2015-07-01

    We investigate the impact that warm dark matter (WDM) has in terms of 21 cm intensity mapping in the post-reionization Universe at z=3−5. We perform hydrodynamic simulations for 5 different models: cold dark matter and WDM with 1,2,3,4 keV (thermal relic) mass and assign the neutral hydrogen a-posteriori using two different methods that both reproduce observations in terms of column density distribution function of neutral hydrogen systems. Contrary to naive expectations, the suppression of power present in the linear and non-linear matter power spectra, results in an increase of power in terms of neutral hydrogen and 21 cm power spectra. This is due to the fact that there is a lack of small mass halos in WDM models with respect to cold dark matter: in order to distribute a total amount of neutral hydrogen within the two cosmological models, a larger quantity has to be placed in the most massive halos, that are more biased compared to the cold dark matter cosmology. We quantify this effect and address significance for the telescope SKA1-LOW, including a realistic noise modeling. The results indicate that we will be able to rule out a 4 keV WDM model with 5000 hours of observations at z>3, with a statistical significance of >3 σ, while a smaller mass of 3 keV, comparable to present day constraints, can be ruled out at more than 2 σ confidence level with 1000 hours of observations at z>5.

  3. Effects of Antenna Beam Chromaticity on Redshifted 21 cm Power Spectrum and Implications for Hydrogen Epoch of Reionization Array

    NASA Astrophysics Data System (ADS)

    Thyagarajan, Nithyanandan; Parsons, Aaron R.; DeBoer, David R.; Bowman, Judd D.; Ewall-Wice, Aaron M.; Neben, Abraham R.; Patra, Nipanjana

    2016-07-01

    Unaccounted for systematics from foregrounds and instruments can severely limit the sensitivity of current experiments from detecting redshifted 21 cm signals from the Epoch of Reionization (EoR). Upcoming experiments are faced with a challenge to deliver more collecting area per antenna element without degrading the data with systematics. This paper and its companions show that dishes are viable for achieving this balance using the Hydrogen Epoch of Reionization Array (HERA) as an example. Here, we specifically identify spectral systematics associated with the antenna power pattern as a significant detriment to all EoR experiments which causes the already bright foreground power to leak well beyond ideal limits and contaminate the otherwise clean EoR signal modes. A primary source of this chromaticity is reflections in the antenna-feed assembly and between structures in neighboring antennas. Using precise foreground simulations taking wide-field effects into account, we provide a generic framework to set cosmologically motivated design specifications on these reflections to prevent further EoR signal degradation. We show that HERA will not be impeded by such spectral systematics and demonstrate that even in a conservative scenario that does not perform removal of foregrounds, HERA will detect the EoR signal in line-of-sight k-modes, {k}\\parallel ≳ 0.2 h Mpc‑1, with high significance. Under these conditions, all baselines in a 19-element HERA layout are capable of detecting EoR over a substantial observing window on the sky.

  4. Effects of Antenna Beam Chromaticity on Redshifted 21 cm Power Spectrum and Implications for Hydrogen Epoch of Reionization Array

    NASA Astrophysics Data System (ADS)

    Thyagarajan, Nithyanandan; Parsons, Aaron R.; DeBoer, David R.; Bowman, Judd D.; Ewall-Wice, Aaron M.; Neben, Abraham R.; Patra, Nipanjana

    2016-07-01

    Unaccounted for systematics from foregrounds and instruments can severely limit the sensitivity of current experiments from detecting redshifted 21 cm signals from the Epoch of Reionization (EoR). Upcoming experiments are faced with a challenge to deliver more collecting area per antenna element without degrading the data with systematics. This paper and its companions show that dishes are viable for achieving this balance using the Hydrogen Epoch of Reionization Array (HERA) as an example. Here, we specifically identify spectral systematics associated with the antenna power pattern as a significant detriment to all EoR experiments which causes the already bright foreground power to leak well beyond ideal limits and contaminate the otherwise clean EoR signal modes. A primary source of this chromaticity is reflections in the antenna-feed assembly and between structures in neighboring antennas. Using precise foreground simulations taking wide-field effects into account, we provide a generic framework to set cosmologically motivated design specifications on these reflections to prevent further EoR signal degradation. We show that HERA will not be impeded by such spectral systematics and demonstrate that even in a conservative scenario that does not perform removal of foregrounds, HERA will detect the EoR signal in line-of-sight k-modes, {k}\\parallel ≳ 0.2 h Mpc-1, with high significance. Under these conditions, all baselines in a 19-element HERA layout are capable of detecting EoR over a substantial observing window on the sky.

  5. Near-term measurements with 21 cm intensity mapping: Neutral hydrogen fraction and BAO at z<2

    SciTech Connect

    Masui, Kiyoshi Wesley; McDonald, Patrick; Pen, Ue-Li

    2010-05-15

    It is shown that 21 cm intensity mapping could be used in the near term to make cosmologically useful measurements. Large scale structure could be detected using existing radio telescopes, or using prototypes for dedicated redshift survey telescopes. This would provide a measure of the mean neutral hydrogen density, using redshift space distortions to break the degeneracy with the linear bias. We find that with only 200 hours of observing time on the Green Bank Telescope, the neutral hydrogen density could be measured to 25% precision at redshift 0.54detection of baryon acoustic oscillations, giving a cosmological distance measure at 3.5% precision. These observation time requirements could be greatly reduced with the construction of multiple pixel receivers. Similar results are possible using prototypes for dedicated cylindrical telescopes on month time scales, or Square Kilometre Array pathfinder aperture arrays on day time scales. Such measurements promise to improve our understanding of these quantities while beating a path for future generations of hydrogen surveys.

  6. Tests of the Tully-Fisher relation. 1: Scatter in infrared magnitude versus 21 cm width

    NASA Technical Reports Server (NTRS)

    Bernstein, Gary M.; Guhathakurta, Puragra; Raychaudhury, Somak; Giovanelli, Riccardo; Haynes, Martha P.; Herter, Terry; Vogt, Nicole P.

    1994-01-01

    We examine the precision of the Tully-Fisher relation (TFR) using a sample of galaxies in the Coma region of the sky, and find that it is good to 5% or better in measuring relative distances. Total magnitudes and disk axis ratios are derived from H and I band surface photometry, and Arecibo 21 cm profiles define the rotation speeds of the galaxies. Using 25 galaxies for which the disk inclination and 21 cm width are well defined, we find an rms deviation of 0.10 mag from a linear TFR with dI/d(log W(sub c)) = -5.6. Each galaxy is assumed to be at a distance proportional to its redshift, and an extinction correction of 1.4(1-b/a) mag is applied to the total I magnitude. The measured scatter is less than 0.15 mag using milder extinction laws from the literature. The I band TFR scatter is consistent with measurement error, and the 95% CL limits on the intrinsic scatter are 0-0.10 mag. The rms scatter using H band magnitudes is 0.20 mag (N = 17). The low width galaxies have scatter in H significantly in excess of known measurement error, but the higher width half of the galaxies have scatter consistent with measurement error. The H band TFR slope may be as steep as the I band slope. As the first applications of this tight correlation, we note the following: (1) the data for the particular spirals commonly used to define the TFR distance to the Coma cluster are inconsistent with being at a common distance and are in fact in free Hubble expansion, with an upper limit of 300 km/s on the rms peculiar line-of-sight velocity of these gas-rich spirals; and (2) the gravitational potential in the disks of these galaxies has typical ellipticity less than 5%. The published data for three nearby spiral galaxies with Cepheid distance determinations are inconsistent with our Coma TFR, suggesting that these local calibrators are either ill-measured or peculiar relative to the Coma Supercluster spirals, or that the TFR has a varying form in different locales.

  7. Improved foreground removal in GMRT 610 MHz observations towards redshifted 21-cm tomography

    NASA Astrophysics Data System (ADS)

    Ghosh, Abhik; Bharadwaj, Somnath; Ali, Sk. Saiyad; Chengalur, Jayaram N.

    2011-12-01

    Foreground removal is a challenge for 21-cm tomography of the high-redshift Universe. We use archival Giant Metrewave Radio Telescope (GMRT) data (obtained for completely different astronomical goals) to estimate the foregrounds at a redshift of ˜1. The statistic we use is the cross power spectrum between two frequencies separated by Δν at the angular multipole ℓ, or equivalently the multi-frequency angular power spectrum Cℓ(Δν). An earlier measurement of Cℓ(Δν) using these data had revealed the presence of oscillatory patterns along Δν, which turned out to be a severe impediment for foreground removal. Using the same data, in this paper we show that it is possible to considerably reduce these oscillations by suppressing the sidelobe response of the primary antenna elements. The suppression works best at the angular multipoles ℓ for which there is a dense sampling of the u-v plane. For three angular multipoles ℓ= 1405, 1602 and 1876, this sidelobe suppression along with a low order polynomial fitting completely results in residuals of (≤ 0.02 mK2), consistent with the noise at the 3σ level. Since the polynomial fitting is done after estimation of the power spectrum it can be ensured that the estimation of the H I signal is not biased. The corresponding 99 per cent upper limit on the H I signal is ?, where ? is the mean neutral fraction and b is the bias.

  8. Erasing the Variable: Empirical Foreground Discovery for Global 21 cm Spectrum Experiments

    NASA Astrophysics Data System (ADS)

    Switzer, Eric R.; Liu, Adrian

    2014-10-01

    Spectral measurements of the 21 cm monopole background have the promise of revealing the bulk energetic properties and ionization state of our universe from z ~ 6-30. Synchrotron foregrounds are orders of magnitude larger than the cosmological signal and are the principal challenge faced by these experiments. While synchrotron radiation is thought to be spectrally smooth and described by relatively few degrees of freedom, the instrumental response to bright foregrounds may be much more complex. To deal with such complexities, we develop an approach that discovers contaminated spectral modes using spatial fluctuations of the measured data. This approach exploits the fact that foregrounds vary across the sky while the signal does not. The discovered modes are projected out of each line of sight of a data cube. An angular weighting then optimizes the cosmological signal amplitude estimate by giving preference to lower-noise regions. Using this method, we show that it is essential for the passband to be stable to at least ~10-4. In contrast, the constraints on the spectral smoothness of the absolute calibration are mainly aesthetic if one is able to take advantage of spatial information. To the extent it is understood, controlling polarization to intensity leakage at the ~10-2 level will also be essential to rejecting Faraday rotation of the polarized synchrotron emission.

  9. Constraining high-redshift X-ray sources with next generation 21-cm power spectrum measurements

    NASA Astrophysics Data System (ADS)

    Ewall-Wice, Aaron; Hewitt, Jacqueline; Mesinger, Andrei; Dillon, Joshua S.; Liu, Adrian; Pober, Jonathan

    2016-05-01

    We use the Fisher matrix formalism and seminumerical simulations to derive quantitative predictions of the constraints that power spectrum measurements on next-generation interferometers, such as the Hydrogen Epoch of Reionization Array (HERA) and the Square Kilometre Array (SKA), will place on the characteristics of the X-ray sources that heated the high-redshift intergalactic medium. Incorporating observations between z = 5 and 25, we find that the proposed 331 element HERA and SKA phase 1 will be capable of placing ≲ 10 per cent constraints on the spectral properties of these first X-ray sources, even if one is unable to perform measurements within the foreground contaminated `wedge' or the FM band. When accounting for the enhancement in power spectrum amplitude from spin temperature fluctuations, we find that the observable signatures of reionization extend well beyond the peak in the power spectrum usually associated with it. We also find that lower redshift degeneracies between the signatures of heating and reionization physics lead to errors on reionization parameters that are significantly greater than previously predicted. Observations over the heating epoch are able to break these degeneracies and improve our constraints considerably. For these two reasons, 21-cm observations during the heating epoch significantly enhance our understanding of reionization as well.

  10. Erasing the Variable: Empirical Foreground Discovery for Global 21 cm Spectrum Experiments

    NASA Technical Reports Server (NTRS)

    Switzer, Eric R.; Liu, Adrian

    2014-01-01

    Spectral measurements of the 21 cm monopole background have the promise of revealing the bulk energetic properties and ionization state of our universe from z approx. 6 - 30. Synchrotron foregrounds are orders of magnitude larger than the cosmological signal, and are the principal challenge faced by these experiments. While synchrotron radiation is thought to be spectrally smooth and described by relatively few degrees of freedom, the instrumental response to bright foregrounds may be much more complex. To deal with such complexities, we develop an approach that discovers contaminated spectral modes using spatial fluctuations of the measured data. This approach exploits the fact that foregrounds vary across the sky while the signal does not. The discovered modes are projected out of each line-of-sight of a data cube. An angular weighting then optimizes the cosmological signal amplitude estimate by giving preference to lower-noise regions. Using this method, we show that it is essential for the passband to be stable to at least approx. 10(exp -4). In contrast, the constraints on the spectral smoothness of the absolute calibration are mainly aesthetic if one is able to take advantage of spatial information. To the extent it is understood, controlling polarization to intensity leakage at the approx. 10(exp -2) level will also be essential to rejecting Faraday rotation of the polarized synchrotron emission. Subject headings: dark ages, reionization, first stars - methods: data analysis - methods: statistical

  11. Development of a Toy Interferometer for Education and Observation of Sun at 21 cm

    NASA Astrophysics Data System (ADS)

    Park, Yong-Sun; Kim, Chang Hee; Choi, Sang In; Lee, Joo Young; Jang, Woo Min; Kim, Woo Yeon; Jeong, Dae Heon

    2008-06-01

    As a continuation of a previous work by Park et al. (2006), we have developed a two-element radio interferometer that can measure both the phase and amplitude of a visibility function. Two small radio telescopes with diameters of 2.3 m are used as before, but this time an external reference oscillator is shared by the two telescopes so that the local oscillator frequencies are identical. We do not use a hardware correlator; instead we record signals from the two telescopes onto a PC and then perform software correlation. Complex visibilities are obtained toward the sun at λ=21 cm, for 24 baselines with the use of the earth rotation and positional changes of one element, where the maximum baseline length projected onto UV plane is ˜ 90 λ. As expected, the visibility amplitude decreases with the baseline length, while the phase is almost constant. The image obtained by the Fourier transformation of the visibility function nicely delineates the sun, which is barely resolved due to the limited baseline length. The experiment demonstrates that this system can be used as a ``toy'' interferometer at least for the education of (under)graduate students.

  12. Erasing the variable: empirical foreground discovery for global 21 cm spectrum experiments

    SciTech Connect

    Switzer, Eric R.; Liu, Adrian

    2014-10-01

    Spectral measurements of the 21 cm monopole background have the promise of revealing the bulk energetic properties and ionization state of our universe from z ∼ 6-30. Synchrotron foregrounds are orders of magnitude larger than the cosmological signal and are the principal challenge faced by these experiments. While synchrotron radiation is thought to be spectrally smooth and described by relatively few degrees of freedom, the instrumental response to bright foregrounds may be much more complex. To deal with such complexities, we develop an approach that discovers contaminated spectral modes using spatial fluctuations of the measured data. This approach exploits the fact that foregrounds vary across the sky while the signal does not. The discovered modes are projected out of each line of sight of a data cube. An angular weighting then optimizes the cosmological signal amplitude estimate by giving preference to lower-noise regions. Using this method, we show that it is essential for the passband to be stable to at least ∼10{sup –4}. In contrast, the constraints on the spectral smoothness of the absolute calibration are mainly aesthetic if one is able to take advantage of spatial information. To the extent it is understood, controlling polarization to intensity leakage at the ∼10{sup –2} level will also be essential to rejecting Faraday rotation of the polarized synchrotron emission.

  13. 2MTF III. H I 21 cm observations of 1194 spiral galaxies with the Green Bank Telescope

    NASA Astrophysics Data System (ADS)

    Masters, Karen L.; Crook, Aidan; Hong, Tao; Jarrett, T. H.; Koribalski, Bärbel S.; Macri, Lucas; Springob, Christopher M.; Staveley-Smith, Lister

    2014-09-01

    We present H I 21 cm observations of 1194 galaxies out to a redshift of 10 000 km s-1 selected as inclined spirals (i ≳ 60°) from the 2MASS redshift survey. These observations were carried out at the National Radio Astronomy Observatory Robert C. Byrd Green Bank Telescope (GBT). This observing programme is part of the 2MASS Tully-Fisher (2MTF) survey. This project will combine H I widths from these GBT observations with those from further dedicated observing at the Parkes Telescope, from the Arecibo Legacy Fast Arecibo L-band Feed Array survey at Arecibo, and S/N > 10 and spectral resolution vres < 10 km s-1 published widths from a variety of telescopes. We will use these H I widths along with 2MASS photometry to estimate Tully-Fisher distances to nearby spirals and investigate the peculiar velocity field of the local Universe. In this paper, we report on detections of neutral hydrogen in emission in 727 galaxies, and measure good signal to noise and symmetric H I global profiles suitable for use in the Tully-Fisher relation in 484.

  14. 21-cm Observations with the Morehead Radio Telescope: Involving Undergraduates in Observing Programs

    NASA Astrophysics Data System (ADS)

    Malphrus, B. K.; Combs, M. S.; Kruth, J.

    2000-12-01

    Herein we report astronomical observations made by undergraduate students with the Morehead Radio Telescope (MRT). The MRT, located at Morehead State University, Morehead, Kentucky, is small aperture (44-ft.) instrument designed by faculty, students, and industrial partners to provide a research instrument and active laboratory for undergraduate astronomy, physics, pre-engineering, and computer science students. Small aperture telescopes like the MRT have numerous advantages as active laboratories and as research instruments. The benefits to students are based upon a hands-on approach to learning concepts in astrophysics and engineering. Students are provided design and research challenges and are allowed to pursue their own solutions. Problem-solving abilities and research design skills are cultivated by this approach. Additionally, there are still contributions that small aperture centimeter-wave instruments can make. The MRT operates over a 6 MHz bandwidth centered at 1420 MHz (21-cm), which corresponds to the hyperfine transition of atomic hydrogen (HI). The HI spatial distribution and flux density associated with cosmic phenomena can be observed and mapped. The dynamics and kinematics of celestial objects can be investigated by observing over a range of frequencies (up to 2.5 MHz) with a 2048-channel back-end spectrometer, providing up to 1 KHz frequency resolution. The sensitivity and versatility of the telescope design facilitate investigation of a wide variety of cosmic phenomena, including supernova remnants, emission and planetary nebulae, extended HI emission from the Milky Way, quasars, radio galaxies, and the sun. Student observations of galactic sources herein reported include Taurus A, Cygnus X, and the Rosette Nebula. Additionally, we report observations of extragalactic phenomena, including Cygnus A, 3C 147, and 3C 146. These observations serve as a performance and capability test-bed of the MRT. In addition to the astronomical results of these

  15. A Flux Scale for Southern Hemisphere 21 cm Epoch of Reionization Experiments

    NASA Astrophysics Data System (ADS)

    Jacobs, Daniel C.; Parsons, Aaron R.; Aguirre, James E.; Ali, Zaki; Bowman, Judd; Bradley, Richard F.; Carilli, Chris L.; DeBoer, David R.; Dexter, Matthew R.; Gugliucci, Nicole E.; Klima, Pat; MacMahon, Dave H. E.; Manley, Jason R.; Moore, David F.; Pober, Jonathan C.; Stefan, Irina I.; Walbrugh, William P.

    2013-10-01

    We present a catalog of spectral measurements covering a 100-200 MHz band for 32 sources, derived from observations with a 64 antenna deployment of the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) in South Africa. For transit telescopes such as PAPER, calibration of the primary beam is a difficult endeavor and errors in this calibration are a major source of error in the determination of source spectra. In order to decrease our reliance on an accurate beam calibration, we focus on calibrating sources in a narrow declination range from -46° to -40°. Since sources at similar declinations follow nearly identical paths through the primary beam, this restriction greatly reduces errors associated with beam calibration, yielding a dramatic improvement in the accuracy of derived source spectra. Extrapolating from higher frequency catalogs, we derive the flux scale using a Monte Carlo fit across multiple sources that includes uncertainty from both catalog and measurement errors. Fitting spectral models to catalog data and these new PAPER measurements, we derive new flux models for Pictor A and 31 other sources at nearby declinations; 90% are found to confirm and refine a power-law model for flux density. Of particular importance is the new Pictor A flux model, which is accurate to 1.4% and shows that between 100 MHz and 2 GHz, in contrast with previous models, the spectrum of Pictor A is consistent with a single power law given by a flux at 150 MHz of 382 ± 5.4 Jy and a spectral index of -0.76 ± 0.01. This accuracy represents an order of magnitude improvement over previous measurements in this band and is limited by the uncertainty in the catalog measurements used to estimate the absolute flux scale. The simplicity and improved accuracy of Pictor A's spectrum make it an excellent calibrator in a band important for experiments seeking to measure 21 cm emission from the epoch of reionization.

  16. The impact of spin-temperature fluctuations on the 21-cm moments

    NASA Astrophysics Data System (ADS)

    Watkinson, C. A.; Pritchard, J. R.

    2015-12-01

    This paper considers the impact of Lyman α coupling and X-ray heating on the 21-cm brightness-temperature one-point statistics (as predicted by seminumerical simulations). The X-ray production efficiency is varied over four orders of magnitude and the hardness of the X-ray spectrum is varied from that predicted for high-mass X-ray binaries, to the softer spectrum expected from the hot interstellar medium. We find peaks in the redshift evolution of both the variance and skewness associated with the efficiency of X-ray production. The amplitude of the variance is also sensitive to the hardness of the X-ray spectral energy distribution. We find that the relative timing of the coupling and heating phases can be inferred from the redshift extent of a plateau that connects a peak in the variance's evolution associated with Lyman α coupling to the heating peak. Importantly, we find that late X-ray heating would seriously hamper our ability to constrain reionization with the variance. Late X-ray heating also qualitatively alters the evolution of the skewness, providing a clean way to constrain such models. If foregrounds can be removed, we find that LOFAR, MWA and PAPER could constrain reionization and late X-ray heating models with the variance. We find that HERA and SKA (phase 1) will be able to constrain both reionization and heating by measuring the variance using foreground-avoidance techniques. If foregrounds can be removed they will also be able to constrain the nature of Lyman α coupling.

  17. A Practical Theorem on Using Interferometry to Measure the Global 21-cm Signal

    NASA Astrophysics Data System (ADS)

    Venumadhav, Tejaswi; Chang, Tzu-Ching; Doré, Olivier; Hirata, Christopher M.

    2016-08-01

    The sky-averaged, or global, background of redshifted 21 cm radiation is expected to be a rich source of information on cosmological reheating and reionization. However, measuring the signal is technically challenging: one must extract a small, frequency-dependent signal from under much brighter spectrally smooth foregrounds. Traditional approaches to study the global signal have used single antennas, which require one to calibrate out the frequency-dependent structure in the overall system gain (due to internal reflections, for example) as well as remove the noise bias from auto-correlating a single amplifier output. This has motivated proposals to measure the signal using cross-correlations in interferometric setups, where additional calibration techniques are available. In this paper we focus on the general principles driving the sensitivity of the interferometric setups to the global signal. We prove that this sensitivity is directly related to two characteristics of the setup: the cross-talk between readout channels (i.e., the signal picked up at one antenna when the other one is driven) and the correlated noise due to thermal fluctuations of lossy elements (e.g., absorbers or the ground) radiating into both channels. Thus in an interferometric setup, one cannot suppress cross-talk and correlated thermal noise without reducing sensitivity to the global signal by the same factor—instead, the challenge is to characterize these effects and their frequency dependence. We illustrate our general theorem by explicit calculations within toy setups consisting of two short-dipole antennas in free space and above a perfectly reflecting ground surface, as well as two well-separated identical lossless antennas arranged to achieve zero cross-talk.

  18. On using large scale correlation of the Ly-α forest and redshifted 21-cm signal to probe HI distribution during the post reionization era

    SciTech Connect

    Sarkar, Tapomoy Guha; Datta, Kanan K. E-mail: kanan.physics@presiuniv.ac.in

    2015-08-01

    We investigate the possibility of detecting the 3D cross correlation power spectrum of the Ly-α forest and HI 21 cm signal from the post reionization epoch. (The cross-correlation signal is directly dependent on the dark matter power spectrum and is sensitive to the 21-cm brightness temperature and Ly-α forest biases. These bias parameters dictate the strength of anisotropy in redshift space.) We find that the cross-correlation power spectrum can be detected using 400 hrs observation with SKA-mid (phase 1) and a futuristic BOSS like experiment with a quasar (QSO) density of 30 deg{sup −2} at a peak SNR of 15 for a single field experiment at redshift z = 2.5. on large scales using the linear bias model. We also study the possibility of constraining various bias parameters using the cross power spectrum. We find that with the same experiment 1 σ (conditional errors) on the 21-cm linear redshift space distortion parameter β{sub T} and β{sub F} corresponding to the Ly-α  forest are ∼ 2.7 % and ∼ 1.4 % respectively for 01 independent pointings of the SKA-mid (phase 1). This prediction indicates a significant improvement over existing measurements. We claim that the detection of the 3D cross correlation power spectrum will not only ascertain the cosmological origin of the signal in presence of astrophysical foregrounds but will also provide stringent constraints on large scale HI biases. This provides an independent probe towards understanding cosmological structure formation.

  19. Models of the Cosmological 21 cm Signal from the Epoch of Reionization Calibrated with Lyα and CMB Data

    NASA Astrophysics Data System (ADS)

    Kulkarni, Girish; Choudhury, Tirthankar Roy; Puchwein, Ewald; Haehnelt, Martin G.

    2016-08-01

    We present here 21 cm predictions from high dynamic range simulations for a range of reionization histories that have been tested against available Lyα and CMB data. We assess the observability of the predicted spatial 21 cm fluctuations by ongoing and upcoming experiments in the late stages of reionization in the limit in which the hydrogen spin temperature is significantly larger than the CMB temperature. Models consistent with the available Lyα data and CMB measurement of the Thomson optical depth predict typical values of 10-20 mK2 for the variance of the 21 cm brightness temperature at redshifts z = 7-10 at scales accessible to ongoing and upcoming experiments (k ≲ 1 cMpc-1h). This is within a factor of a few magnitude of the sensitivity claimed to have been already reached by ongoing experiments in the signal rms value. Our different models for the reionization history make markedly different predictions for the redshift evolution and thus frequency dependence of the 21 cm power spectrum and should be easily discernible by LOFAR (and later HERA and SKA1) at their design sensitivity. Our simulations have sufficient resolution to assess the effect of high-density Lyman limit systems that can self-shield against ionizing radiation and stay 21 cm bright even if the hydrogen in their surroundings is highly ionized. Our simulations predict that including the effect of the self-shielded gas in highly ionized regions reduces the large scale 21 cm power by about 30%.

  20. H I SHELLS AND SUPERSHELLS IN THE I-GALFA H I 21 cm LINE SURVEY. I. FAST-EXPANDING H I SHELLS ASSOCIATED WITH SUPERNOVA REMNANTS

    SciTech Connect

    Park, G.; Koo, B.-C.; Gibson, S. J.; Newton, J. H.; Kang, J.-H.; Lane, D. C.; Douglas, K. A.; Peek, J. E. G.; Korpela, E. J.; Heiles, C.

    2013-11-01

    We search for fast-expanding H I shells associated with Galactic supernova remnants (SNRs) in the longitude range l ≈ 32° to 77° using 21 cm line data from the Inner-Galaxy Arecibo L-band Feed Array (I-GALFA) H I survey. Among the 39 known Galactic SNRs in this region, we find such H I shells in 4 SNRs: W44, G54.4-0.3, W51C, and CTB 80. All four were previously identified in low-resolution surveys, and three of those (excluding G54.4-0.3) were previously studied with the Arecibo telescope. A remarkable new result, however, is the detection of H I emission at both very high positive and negative velocities in W44 from the receding and approaching parts of the H I expanding shell, respectively. This is the first detection of both sides of an expanding shell associated with an SNR in H I 21 cm emission. The high-resolution I-GALFA survey data also reveal a prominent expanding H I shell with high circular symmetry associated with G54.4-0.3. We explore the physical characteristics of four SNRs and discuss what differentiates them from other SNRs in the survey area. We conclude that these four SNRs are likely the remnants of core-collapse supernovae interacting with a relatively dense (∼> 1 cm{sup –3}) ambient medium, and we discuss the visibility of SNRs in the H I 21 cm line.

  1. A FLUX SCALE FOR SOUTHERN HEMISPHERE 21 cm EPOCH OF REIONIZATION EXPERIMENTS

    SciTech Connect

    Jacobs, Daniel C.; Bowman, Judd; Parsons, Aaron R.; Ali, Zaki; Pober, Jonathan C.; Aguirre, James E.; Moore, David F.; Bradley, Richard F.; Carilli, Chris L.; DeBoer, David R.; Dexter, Matthew R.; MacMahon, Dave H. E.; Gugliucci, Nicole E.; Klima, Pat; Manley, Jason R.; Walbrugh, William P.; Stefan, Irina I.

    2013-10-20

    We present a catalog of spectral measurements covering a 100-200 MHz band for 32 sources, derived from observations with a 64 antenna deployment of the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) in South Africa. For transit telescopes such as PAPER, calibration of the primary beam is a difficult endeavor and errors in this calibration are a major source of error in the determination of source spectra. In order to decrease our reliance on an accurate beam calibration, we focus on calibrating sources in a narrow declination range from –46° to –40°. Since sources at similar declinations follow nearly identical paths through the primary beam, this restriction greatly reduces errors associated with beam calibration, yielding a dramatic improvement in the accuracy of derived source spectra. Extrapolating from higher frequency catalogs, we derive the flux scale using a Monte Carlo fit across multiple sources that includes uncertainty from both catalog and measurement errors. Fitting spectral models to catalog data and these new PAPER measurements, we derive new flux models for Pictor A and 31 other sources at nearby declinations; 90% are found to confirm and refine a power-law model for flux density. Of particular importance is the new Pictor A flux model, which is accurate to 1.4% and shows that between 100 MHz and 2 GHz, in contrast with previous models, the spectrum of Pictor A is consistent with a single power law given by a flux at 150 MHz of 382 ± 5.4 Jy and a spectral index of –0.76 ± 0.01. This accuracy represents an order of magnitude improvement over previous measurements in this band and is limited by the uncertainty in the catalog measurements used to estimate the absolute flux scale. The simplicity and improved accuracy of Pictor A's spectrum make it an excellent calibrator in a band important for experiments seeking to measure 21 cm emission from the epoch of reionization.

  2. THE IMPACT OF THE SUPERSONIC BARYON-DARK MATTER VELOCITY DIFFERENCE ON THE z {approx} 20 21 cm BACKGROUND

    SciTech Connect

    McQuinn, Matthew; O'Leary, Ryan M.

    2012-11-20

    Recently, Tseliakhovich and Hirata showed that during the cosmic Dark Ages the baryons were typically moving supersonically with respect to the dark matter with a spatially variable Mach number. Such supersonic motion may source shocks that inhomogeneously heat the universe. This motion may also suppress star formation in the first halos. Even a small amount of coupling of the 21 cm signal to this motion has the potential to vastly enhance the 21 cm brightness temperature fluctuations at 15 {approx}< z {approx}< 40, as well as to imprint distinctive acoustic oscillations in this signal. We present estimates for the size of this coupling, which we calibrate with a suite of cosmological simulations of the high-redshift universe using the GADGET and Enzo codes. Our simulations, discussed in detail in a companion paper, are initialized to self-consistently account for gas pressure and the dark matter-baryon relative velocity, v {sub bc} (in contrast to prior simulations). We find that the supersonic velocity difference dramatically suppresses structure formation on 10-100 comoving kpc scales, it sources shocks throughout the universe, and it impacts the accretion of gas onto the first star-forming minihalos (even for halo masses as large as 10{sup 7} M {sub Sun }). However, prior to reheating by astrophysical sources, we find that the v {sub bc}-sourced temperature fluctuations can contribute only as much as Almost-Equal-To 10% of the fluctuations in the 21 cm signal. We do find that v {sub bc} in certain scenarios could source an O(1) component in the power spectrum of the 21 cm background on observable scales via the X-ray (but not ultraviolet) backgrounds produced once the first stars formed. In a scenario in which {approx}10{sup 6} M {sub Sun} minihalos reheated the universe via their X-ray backgrounds, we find that the pre-reionization 21 cm signal would be larger than previously anticipated and exhibit more significant acoustic features. Such features would be a

  3. A GREEN BANK TELESCOPE SURVEY FOR H I 21 cm ABSORPTION IN THE DISKS AND HALOS OF LOW-REDSHIFT GALAXIES

    SciTech Connect

    Borthakur, Sanchayeeta; Tripp, Todd M.; Yun, Min S.; Meiring, Joseph D.; Bowen, David V.; York, Donald G.; Momjian, Emmanuel

    2011-01-20

    We present an H I 21 cm absorption survey with the Green Bank Telescope (GBT) of galaxy-quasar pairs selected by combining galaxy data from the Sloan Digital Sky Survey (SDSS) and radio sources from the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey. Our sample consists of 23 sight lines through 15 low-redshift foreground galaxy-background quasar pairs with impact parameters ranging from 1.7 kpc up to 86.7 kpc. We detected one absorber in the GBT survey from the foreground dwarf galaxy, GQ1042+0747, at an impact parameter of 1.7 kpc and another possible absorber in our follow-up Very Large Array (VLA) imaging of the nearby foreground galaxy UGC 7408. The line widths of both absorbers are narrow (FWHM of 3.6 and 4.8km s{sup -1}). The absorbers have sub-damped Ly{alpha} column densities, and most likely originate in the disk gas of the foreground galaxies. We also detected H I emission from three foreground galaxies including UGC 7408. Although our sample contains both blue and red galaxies, the two H I absorbers as well as the H I emissions are associated with blue galaxies. We discuss the physical conditions in the 21 cm absorbers and some drawbacks of the large GBT beam for this type of survey.

  4. Probing primordial non-Gaussianity: the 3D Bispectrum of Ly-α forest and the redshifted 21-cm signal from the post reionization epoch

    SciTech Connect

    Sarkar, Tapomoy Guha; Hazra, Dhiraj Kumar E-mail: dhiraj@apctp.org

    2013-04-01

    We explore possibility of using the three dimensional bispectra of the Ly-α forest and the redshifted 21-cm signal from the post-reionization epoch to constrain primordial non-Gaussianity. Both these fields map out the large scale distribution of neutral hydrogen and maybe treated as tracers of the underlying dark matter field. We first present the general formalism for the auto and cross bispectrum of two arbitrary three dimensional biased tracers and then apply it to the specific case. We have modeled the 3D Ly-α transmitted flux field as a continuous tracer sampled along 1D skewers which corresponds to quasars sight lines. For the post reionization 21-cm signal we have used a linear bias model. We use a Fisher matrix analysis to present the first prediction for bounds on f{sub NL} and the other bias parameters using the three dimensional 21-cm bispectrum and other cross bispectra. The bounds on f{sub NL} depend on the survey volume, and the various observational noises. We have considered a BOSS like Ly-α survey where the average number density of quasars n-bar = 10{sup −3}Mpc{sup −2} and the spectra are measured at a 2-σ level. For the 21-cm signal we have considered a 4000 hrs observation with a futuristic SKA like radio array. We find that bounds on f{sub NL} obtained in our analysis (6 ≤ Δf{sub NL} ≤ 65) is competitive with CMBR and galaxy surveys and may prove to be an important alternative approach towards constraining primordial physics using future data sets. Further, we have presented a hierarchy of power of the bispectrum-estimators towards detecting the f{sub NL}. Given the quality of the data sets, one may use this method to optimally choose the right estimator and thereby provide better constraints on f{sub NL}. We also find that by combining the various cross-bispectrum estimators it is possible to constrain f{sub NL} at a level Δf{sub NL} ∼ 4.7. For the equilateral and orthogonal template we obtain Δf{sub NL}{sup equ} ∼ 17 and

  5. X-rays and hard ultraviolet radiation from the first galaxies: ionization bubbles and 21-cm observations

    NASA Astrophysics Data System (ADS)

    Venkatesan, Aparna; Benson, Andrew

    2011-11-01

    The first stars and quasars are known sources of hard ionizing radiation in the first billion years of the Universe. We examine the joint effects of X-rays and hard ultraviolet (UV) radiation from such first-light sources on the hydrogen and helium reionization of the intergalactic medium (IGM) at early times, and the associated heating. We study the growth and evolution of individual H II, He II and He III regions around early galaxies with first stars and/or quasi-stellar object populations. We find that in the presence of helium-ionizing radiation, X-rays may not dominate the ionization and thermal history of the IGM at z˜ 10-20, contributing relatively modest increases to IGM ionization and heating up to ˜103-105 K in IGM temperatures. We also calculate the 21-cm signal expected from a number of scenarios with metal-free starbursts and quasars in varying combinations and masses at these redshifts. The peak values for the spin temperature reach ˜104-105 K in such cases. The maximum values for the 21-cm brightness temperature are around 30-40 mK in emission, while the net values of the 21-cm absorption signal range from ˜a few to 60 mK on scales of 0.01-1 Mpc. We find that the 21-cm signature of X-ray versus UV ionization could be distinct, with the emission signal expected from X-rays alone occurring at smaller scales than that from UV radiation, resulting from the inherently different spatial scales at which X-ray and UV ionization/heating manifests. This difference is time-dependent and becomes harder to distinguish with an increasing X-ray contribution to the total ionizing photon production. Such differing scale-dependent contributions from X-ray and UV photons may therefore 'blur' the 21-cm signature of the percolation of ionized bubbles around early haloes (depending on whether a cosmic X-ray or UV background is built up first) and affect the interpretation of 21-cm data constraints on reionization.

  6. Probing reionization with the cross-power spectrum of 21 cm and near-infrared radiation backgrounds

    SciTech Connect

    Mao, Xiao-Chun

    2014-08-01

    The cross-correlation between the 21 cm emission from the high-redshift intergalactic medium and the near-infrared (NIR) background light from high-redshift galaxies promises to be a powerful probe of cosmic reionization. In this paper, we investigate the cross-power spectrum during the epoch of reionization. We employ an improved halo approach to derive the distribution of the density field and consider two stellar populations in the star formation model: metal-free stars and metal-poor stars. The reionization history is further generated to be consistent with the electron-scattering optical depth from cosmic microwave background measurements. Then, the intensity of the NIR background is estimated by collecting emission from stars in first-light galaxies. On large scales, we find that the 21 cm and NIR radiation backgrounds are positively correlated during the very early stages of reionization. However, these two radiation backgrounds quickly become anti-correlated as reionization proceeds. The maximum absolute value of the cross-power spectrum is |Δ{sub 21,NIR}{sup 2}|∼10{sup −4} mK nW m{sup –2} sr{sup –1}, reached at ℓ ∼ 1000 when the mean fraction of ionized hydrogen is x-bar{sub i}∼0.9. We find that Square Kilometer Array can measure the 21 cm-NIR cross-power spectrum in conjunction with mild extensions to the existing CIBER survey, provided that the integration time independently adds up to 1000 and 1 hr for 21 cm and NIR observations, and that the sky coverage fraction of the CIBER survey is extended from 4 × 10{sup –4} to 0.1. Measuring the cross-correlation signal as a function of redshift provides valuable information on reionization and helps confirm the origin of the 'missing' NIR background.

  7. LOFAR insights into the epoch of reionization from the cross-power spectrum of 21 cm emission and galaxies

    NASA Astrophysics Data System (ADS)

    Wiersma, R. P. C.; Ciardi, B.; Thomas, R. M.; Harker, G. J. A.; Zaroubi, S.; Bernardi, G.; Brentjens, M.; de Bruyn, A. G.; Daiboo, S.; Jelic, V.; Kazemi, S.; Koopmans, L. V. E.; Labropoulos, P.; Martinez, O.; Mellema, G.; Offringa, A.; Pandey, V. N.; Schaye, J.; Veligatla, V.; Vedantham, H.; Yatawatta, S.

    2013-07-01

    Using a combination of N-body simulations, semi-analytic models and radiative transfer calculations, we have estimated the theoretical cross-power spectrum between galaxies and the 21 cm emission from neutral hydrogen during the epoch of reionization. In accordance with previous studies, we find that the 21 cm emission is initially correlated with haloes on large scales (≳30 Mpc), anticorrelated on intermediate (˜5 Mpc) and uncorrelated on small (≲3 Mpc) scales. This picture quickly changes as reionization proceeds and the two fields become anticorrelated on large scales. The normalization of the cross-power spectrum can be used to set constraints on the average neutral fraction in the intergalactic medium and its shape can be a powerful tool to study the topology of reionization. When we apply a drop-out technique to select galaxies and add to the 21 cm signal the noise expected from the LOw Frequency ARray (LOFAR) telescope, we find that while the normalization of the cross-power spectrum remains a useful tool for probing reionization, its shape becomes too noisy to be informative. On the other hand, for an Lyα Emitter (LAE) survey both the normalization and the shape of the cross-power spectrum are suitable probes of reionization. A closer look at a specific planned LAE observing program using Subaru Hyper-Suprime Cam reveals concerns about the strength of the 21 cm signal at the planned redshifts. If the ionized fraction at z ˜ 7 is lower than the one estimated here, then using the cross-power spectrum may be a useful exercise given that at higher redshifts and neutral fractions it is able to distinguish between two toy models with different topologies.

  8. Precise Measurement of the Reionization Optical Depth from the Global 21 cm Signal Accounting for Cosmic Heating

    NASA Astrophysics Data System (ADS)

    Fialkov, Anastasia; Loeb, Abraham

    2016-04-01

    As a result of our limited data on reionization, the total optical depth for electron scattering, τ, limits precision measurements of cosmological parameters from the Cosmic Microwave Background (CMB). It was recently shown that the predicted 21 cm signal of neutral hydrogen contains enough information to reconstruct τ with sub-percent accuracy, assuming that the neutral gas was much hotter than the CMB throughout the entire epoch of reionization (EoR). Here we relax this assumption and use the global 21 cm signal alone to extract τ for realistic X-ray heating scenarios. We test our model-independent approach using mock data for a wide range of ionization and heating histories and show that an accurate measurement of the reionization optical depth at a sub-percent level is possible in most of the considered scenarios even when heating is not saturated during the EoR, assuming that the foregrounds are mitigated. However, we find that in cases where heating sources had hard X-ray spectra and their luminosity was close to or lower than what is predicted based on low-redshift observations, the global 21 cm signal alone is not a good tracer of the reionization history.

  9. How Ewen and Purcell discovered the 21-cm interstellar hydrogen line.

    NASA Astrophysics Data System (ADS)

    Stephan, K. D.

    1999-02-01

    The story of how Harold Irving Ewen and Edward Mills Purcell detected the first spectral line ever observed in radio astronomy, in 1951, has been told for general audiences by Robert Buderi (1996). The present article has a different purpose. The technical roots of Ewen and Purcell's achievement reveal much about the way science often depends upon "borrowed" technologies, which were not developed with the needs of science in mind. The design and construction of the equipment is described in detail. As Ewen's photographs, records, and recollections show, he and Purcell had access to an unusual combination of scientific knowledge, engineering know-how, critical hardware, and technical assistance at Harvard, in 1950 and 1951. This combination gave them a competitive edge over similar research groups in Holland and Australia, who were also striving to detect the hydrogen line, and who succeeded only weeks after the Harvard researchers did. The story also shows that Ewen and Purcell did their groundbreaking scientific work in the "small-science" style that prevailed before World War II, while receiving substantial indirect help from one of the first big-science projects at Harvard.

  10. Constraints on the temperature of the intergalactic medium at z = 8.4 with 21-cm observations

    NASA Astrophysics Data System (ADS)

    Greig, Bradley; Mesinger, Andrei; Pober, Jonathan C.

    2016-02-01

    We compute robust lower limits on the spin temperature, TS, of the z = 8.4 intergalactic medium (IGM), implied by the upper limits on the 21-cm power spectrum recently measured by PAPER-64. Unlike previous studies which used a single epoch of reionization (EoR) model, our approach samples a large parameter space of EoR models: the dominant uncertainty when estimating constraints on TS. Allowing TS to be a free parameter and marginalizing over EoR parameters in our Markov Chain Monte Carlo code 21CMMC, we infer TS ≥ 3 K (corresponding approximately to 1σ) for a mean IGM neutral fraction of bar{x}_{HI}≳ 0.1. We further improve on these limits by folding-in additional EoR constraints based on: (i) the dark fraction in QSO spectra, which implies a strict upper limit of bar{x}_{HI}[z=5.9]≤ 0.06+0.05 (1σ ); and (ii) the electron scattering optical depth, τe = 0.066 ± 0.016 (1σ) measured by the Planck satellite. By restricting the allowed EoR models, these additional observations tighten the approximate 1σ lower limits on the spin temperature to TS ≥ 6 K. Thus, even such preliminary 21-cm observations begin to rule out extreme scenarios such as `cold reionization', implying at least some prior heating of the IGM. The analysis framework developed here can be applied to upcoming 21-cm observations, thereby providing unique insights into the sources which heated and subsequently reionized the very early Universe.

  11. Accurate measurement of the H I column density from H I 21 cm absorption-emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Chengalur, Jayaram N.; Kanekar, Nissim; Roy, Nirupam

    2013-07-01

    We present a detailed study of an estimator of the H I column density, based on a combination of H I 21 cm absorption and H I 21cm emission spectroscopy. This `isothermal' estimate is given by NHI, ISO = 1.823 × 1018 ∫ [τtot × TB / [ 1 - e-τtot]dV, where τtot is the total H I 21cm optical depth along the sightline and TB is the measured brightness temperature. We have used a Monte Carlo simulation to quantify the accuracy of the isothermal estimate by comparing the derived NHI, ISO with the true H I column density NHI. The simulation was carried out for a wide range of sightlines, including gas in different temperature phases and random locations along the path. We find that the results are statistically insensitive to the assumed gas temperature distribution and the positions of different phases along the line of sight. The median value of the ratio of the true H I column density to the isothermal estimate, NHI/NHI, ISO, is within a factor of 2 of unity while the 68.2 per cent confidence intervals are within a factor of ≈3 of unity, out to high H I column densities, ≤5 × 1023 cm-2 per 1 km s-1 channel, and high total optical depths, ≤1000. The isothermal estimator thus provides a significantly better measure of the H I column density than other methods, within a factor of a few of the true value even at the highest columns, and should allow us to directly probe the existence of high H I column density gas in the Milky Way.

  12. Multi-redshift limits on the 21cm power spectrum from PAPER 64: XRays in the early universe

    NASA Astrophysics Data System (ADS)

    Kolopanis, Matthew; Jacobs, Danny; PAPER Collaboration

    2016-06-01

    Here we present new constraints on 21cm emission from cosmic reionization from the 64 element deployment of the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER). These results extend the single redshift 8.4 result presented in Ali et al 2015 to include redshifts from 7.3 to 10.9. These new limits offer as much as a factor of 4 improvement in sensitivity compared to previous 32 element PAPER results by Jacobs et al (2015). Using these limits we place constraints on a parameterized model of heating due to XRays emitted by early collapsed objects.

  13. Improved constraints on possible variation of physical constants from H i 21-cm and molecular QSO absorption lines

    NASA Astrophysics Data System (ADS)

    Murphy, M. T.; Webb, J. K.; Flambaum, V. V.; Drinkwater, M. J.; Combes, F.; Wiklind, T.

    2001-11-01

    Quasar (QSO) absorption spectra provide an extremely useful probe of possible cosmological variation in various physical constants. Comparison of Hi 21-cm absorption with corresponding molecular (rotational) absorption spectra allows us to constrain variation in [formmu2]y≡α2gp, where α is the fine-structure constant and gp is the proton g-factor. We analyse spectra of two QSOs, PKS 1413+135 and TXS 0218+357, and derive values of [formmu3]Δy/y at absorption redshifts of [formmu4]z=0.2467 and 0.6847 by simultaneous fitting of the Hi 21-cm and molecular lines. We find [formmu5]Δy/y=(-0.20+/-0.44)×10-5 and [formmu6]Δy/y=(-0.16+/-0.54)×10-5 respectively, indicating an insignificantly smaller y in the past. We compare our results with other constraints from the same two QSOs given recently by Drinkwater et al. and Carilli et al., and with our recent optical constraints, which indicated a smaller α at higher redshifts.

  14. Detailed 21 cm observations towards the TeV γ-ray SNR HESS J1731-347

    NASA Astrophysics Data System (ADS)

    Fukuda, Tatsuya; Yamamoto, Hiroaki; Fukui, Yasuo; Torii, Kazufumi; Hayakawa, Takahiro; Okuda, Takeshi; Sano, Hidetoshi; Yoshiike, Satoshi

    2012-10-01

    HESS J1731-347 is one of the unique SNRs which show the TeV gamma-ray shell like morphology. Our new study succeeded to reveal the distributions of the ISM proton that coincide well with the TeV gamma-ray distributions and discussed that both the hadronic and leptonic processes are possibly working in this region. However, the present ISM resolutions of a few arcmin of the given data sets are not sufficient to understand the detailed ISM distributions and the origin of the gamma-ray emission. We will use the ATCA to image 21cm radio continuum emission and HI emission in the region to a resolution of ~30" and study the interaction between the shock wave and the ISM in detail. Such results are a crucial component in testing for the origin of SNR gamma-rays.

  15. Wearable sensor for heart rate detection

    NASA Astrophysics Data System (ADS)

    Shi, Cong; Liu, Xiaohua; Kong, Lingqin; Wu, Jizhe; Liu, Ming; Dong, Liquan; Hui, Mei; Zhao, Yuejin

    2015-08-01

    In recent years heart and blood vessel diseases kill more people than everything else combined. The daily test of heart rate for the prevention and treatment of the heart head blood-vessel disease has the vital significance. In order to adapt the transformation of medical model and solve the low accuracy problem of the traditional method of heart rate measuring, we present a new method to monitor heart rate in this paper. The heart rate detection is designed for daily heart rate detection .The heart rate signal is collected by the heart rate sensor. The signal through signal processing circuits converts into sine wave and square wave in turn. And then the signal is transmitted to the computer by data collection card. Finally, we use LABVIEW and MATLAB to show the heart rate wave and calculate the heart rate. By doing contrast experiment with medical heart rate product, experimental results show that the system can realize rapidly and accurately measure the heart rate value. A measurement can be completed within 10 seconds and the error is less than 3beat/min. And the result shows that the method in this paper has a strong anti-interference ability. It can effectively suppress the movement interference. Beyond that the result is insensitive to light.

  16. AGB circumstellar environments probed through the 21 cm atomic hydrogen line emission. A programme for the SKA?

    NASA Astrophysics Data System (ADS)

    Gerard, E.; Le Bertre, T.

    2006-06-01

    Red giant stars are responsible for 70% of the recycling of stellar matter in the local interstellar medium (ISM) through mass loss, mainly along the AGB sequence. Most of the matter in circumstellar shells is hydrogen in atomic (or molecular form). However, up to now, atomic hydrogen has remained largely undetected due to the weakness of its emission, the merging of circumstellar matter with the ambient ISM and the confusion from foreground and background interstellar hydrogen along the same line of sight. With the upgraded Nancay Radiotelescope, we have started a new search for HI at 21 cm towards AGB stars and post-AGBs, including PNs. We illustrate our results on one case, EP~Aqr, which shows that the contamination by interstellar emission must be treated with great care and discuss the prospects with the SKA. In order to sort out the genuine circumstellar HI emission from the interstellar one, it is necessary to map large areas of the sky (at all angular scales from sub-arcsec to degrees) with high spectral resolution, high sensitivity and a large dynamical range.

  17. The Importance of Wide-field Foreground Removal for 21 cm Cosmology: A Demonstration with Early MWA Epoch of Reionization Observations

    NASA Astrophysics Data System (ADS)

    Pober, J. C.; Hazelton, B. J.; Beardsley, A. P.; Barry, N. A.; Martinot, Z. E.; Sullivan, I. S.; Morales, M. F.; Bell, M. E.; Bernardi, G.; Bhat, N. D. R.; Bowman, J. D.; Briggs, F.; Cappallo, R. J.; Carroll, P.; Corey, B. E.; de Oliveira-Costa, A.; Deshpande, A. A.; Dillon, Joshua. S.; Emrich, D.; Ewall-Wice, A. M.; Feng, L.; Goeke, R.; Greenhill, L. J.; Hewitt, J. N.; Hindson, L.; Hurley-Walker, N.; Jacobs, D. C.; Johnston-Hollitt, M.; Kaplan, D. L.; Kasper, J. C.; Kim, Han-Seek; Kittiwisit, P.; Kratzenberg, E.; Kudryavtseva, N.; Lenc, E.; Line, J.; Loeb, A.; Lonsdale, C. J.; Lynch, M. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morgan, E.; Neben, A. R.; Oberoi, D.; Offringa, A. R.; Ord, S. M.; Paul, Sourabh; Pindor, B.; Prabu, T.; Procopio, P.; Riding, J.; Rogers, A. E. E.; Roshi, A.; Sethi, Shiv K.; Udaya Shankar, N.; Srivani, K. S.; Subrahmanyan, R.; Tegmark, M.; Thyagarajan, Nithyanandan; Tingay, S. J.; Trott, C. M.; Waterson, M.; Wayth, R. B.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.; Wyithe, J. S. B.

    2016-03-01

    In this paper we present observations, simulations, and analysis demonstrating the direct connection between the location of foreground emission on the sky and its location in cosmological power spectra from interferometric redshifted 21 cm experiments. We begin with a heuristic formalism for understanding the mapping of sky coordinates into the cylindrically averaged power spectra measurements used by 21 cm experiments, with a focus on the effects of the instrument beam response and the associated sidelobes. We then demonstrate this mapping by analyzing power spectra with both simulated and observed data from the Murchison Widefield Array. We find that removing a foreground model that includes sources in both the main field of view and the first sidelobes reduces the contamination in high k∥ modes by several per cent relative to a model that only includes sources in the main field of view, with the completeness of the foreground model setting the principal limitation on the amount of power removed. While small, a percent-level amount of foreground power is in itself more than enough to prevent recovery of any Epoch of Reionization signal from these modes. This result demonstrates that foreground subtraction for redshifted 21 cm experiments is truly a wide-field problem, and algorithms and simulations must extend beyond the instrument’s main field of view to potentially recover the full 21 cm power spectrum.

  18. Drowsiness detection using heart rate variability.

    PubMed

    Vicente, José; Laguna, Pablo; Bartra, Ariadna; Bailón, Raquel

    2016-06-01

    It is estimated that 10-30 % of road fatalities are related to drowsy driving. Driver's drowsiness detection based on biological and vehicle signals is being studied in preventive car safety. Autonomous nervous system activity, which can be measured noninvasively from the heart rate variability (HRV) signal obtained from surface electrocardiogram, presents alterations during stress, extreme fatigue and drowsiness episodes. We hypothesized that these alterations manifest on HRV and thus could be used to detect driver's drowsiness. We analyzed three driving databases in which drivers presented different sleep-deprivation levels, and in which each driving minute was annotated as drowsy or awake. We developed two different drowsiness detectors based on HRV. While the drowsiness episodes detector assessed each minute of driving as "awake" or "drowsy" with seven HRV derived features (positive predictive value 0.96, sensitivity 0.59, specificity 0.98 on 3475 min of driving), the sleep-deprivation detector discerned if a driver was suitable for driving or not, at driving onset, as function of his sleep-deprivation state. Sleep-deprivation state was estimated from the first three minutes of driving using only one HRV feature (positive predictive value 0.80, sensitivity 0.62, specificity 0.88 on 30 drivers). Incorporating drowsiness assessment based on HRV signal may add significant improvements to existing car safety systems.

  19. Drowsiness detection using heart rate variability.

    PubMed

    Vicente, José; Laguna, Pablo; Bartra, Ariadna; Bailón, Raquel

    2016-06-01

    It is estimated that 10-30 % of road fatalities are related to drowsy driving. Driver's drowsiness detection based on biological and vehicle signals is being studied in preventive car safety. Autonomous nervous system activity, which can be measured noninvasively from the heart rate variability (HRV) signal obtained from surface electrocardiogram, presents alterations during stress, extreme fatigue and drowsiness episodes. We hypothesized that these alterations manifest on HRV and thus could be used to detect driver's drowsiness. We analyzed three driving databases in which drivers presented different sleep-deprivation levels, and in which each driving minute was annotated as drowsy or awake. We developed two different drowsiness detectors based on HRV. While the drowsiness episodes detector assessed each minute of driving as "awake" or "drowsy" with seven HRV derived features (positive predictive value 0.96, sensitivity 0.59, specificity 0.98 on 3475 min of driving), the sleep-deprivation detector discerned if a driver was suitable for driving or not, at driving onset, as function of his sleep-deprivation state. Sleep-deprivation state was estimated from the first three minutes of driving using only one HRV feature (positive predictive value 0.80, sensitivity 0.62, specificity 0.88 on 30 drivers). Incorporating drowsiness assessment based on HRV signal may add significant improvements to existing car safety systems. PMID:26780463

  20. THE 21 cm 'OUTER ARM' AND THE OUTER-GALAXY HIGH-VELOCITY CLOUDS: CONNECTED BY KINEMATICS, METALLICITY, AND DISTANCE

    SciTech Connect

    Tripp, Todd M.; Song Limin

    2012-02-20

    Using high-resolution ultraviolet spectra obtained with the Hubble Space Telescope Space Telescope Imaging Spectrograph and the Far Ultraviolet Spectroscopic Explorer, we study the metallicity, kinematics, and distance of the gaseous 'outer arm' (OA) and the high-velocity clouds (HVCs) in the outer Galaxy. We detect the OA in a variety of absorption lines toward two QSOs, H1821+643 and HS0624+6907. We search for OA absorption toward eight Galactic stars and detect it in one case, which constrains the OA Galactocentric radius to 9 kpc detect HVC Complex G, which is projected near the OA at a similar velocity, in absorption toward two stars; Complex G is therefore in the same region at R{sub G} = 8-10 kpc. HVC Complex C is known to be at a similar Galactocentric radius. Toward H1821+643, the low-ionization absorption lines are composed of multiple narrow components, indicating the presence of several cold clouds and rapid cooling and fragmentation. Some of the highly ionized gas is also surprisingly cool. Accounting for ionization corrections, we find that the OA metallicity is Z = 0.2-0.5 Z{sub Sun }, but nitrogen is underabundant and some species are possibly mildly depleted by dust. The similarity of the OA metallicity, Galactocentric location, and kinematics to those of the adjacent outer-Galaxy HVCs, including high velocities that are not consistent with Galactic rotation, suggests that the OA and outer-Galaxy HVCs could have a common origin.

  1. New limits on 21 cm epoch of reionization from paper-32 consistent with an x-ray heated intergalactic medium at z = 7.7

    SciTech Connect

    Parsons, Aaron R.; Liu, Adrian; Ali, Zaki S.; Pober, Jonathan C.; Aguirre, James E.; Moore, David F.; Bradley, Richard F.; Carilli, Chris L.; DeBoer, David R.; Dexter, Matthew R.; MacMahon, David H. E.; Gugliucci, Nicole E.; Jacobs, Daniel C.; Klima, Pat; Manley, Jason R.; Walbrugh, William P.; Stefan, Irina I.

    2014-06-20

    We present new constraints on the 21 cm Epoch of Reionization (EoR) power spectrum derived from three months of observing with a 32 antenna, dual-polarization deployment of the Donald C. Backer Precision Array for Probing the Epoch of Reionization in South Africa. In this paper, we demonstrate the efficacy of the delay-spectrum approach to avoiding foregrounds, achieving over eight orders of magnitude of foreground suppression (in mK{sup 2}). Combining this approach with a procedure for removing off-diagonal covariances arising from instrumental systematics, we achieve a best 2σ upper limit of (41 mK){sup 2} for k = 0.27 h Mpc{sup –1} at z = 7.7. This limit falls within an order of magnitude of the brighter predictions of the expected 21 cm EoR signal level. Using the upper limits set by these measurements, we generate new constraints on the brightness temperature of 21 cm emission in neutral regions for various reionization models. We show that for several ionization scenarios, our measurements are inconsistent with cold reionization. That is, heating of the neutral intergalactic medium (IGM) is necessary to remain consistent with the constraints we report. Hence, we have suggestive evidence that by z = 7.7, the H I has been warmed from its cold primordial state, probably by X-rays from high-mass X-ray binaries or miniquasars. The strength of this evidence depends on the ionization state of the IGM, which we are not yet able to constrain. This result is consistent with standard predictions for how reionization might have proceeded.

  2. Expected constraints on models of the epoch of reionization with the variance and skewness in redshifted 21 cm-line fluctuations

    NASA Astrophysics Data System (ADS)

    Kubota, Kenji; Yoshiura, Shintaro; Shimabukuro, Hayato; Takahashi, Keitaro

    2016-08-01

    The redshifted 21 cm-line signal from neutral hydrogen in the intergalactic medium (IGM) gives a direct probe of the epoch of reionization (EoR). In this paper, we investigate the potential of the variance and skewness of the probability distribution function of the 21 cm brightness temperature for constraining EoR models. These statistical quantities are simple, easy to calculate from the observed visibility, and thus suitable for the early exploration of the EoR with current telescopes such as the Murchison Widefield Array (MWA) and LOw Frequency ARray (LOFAR). We show, by performing Fisher analysis, that the variance and skewness at z = 7-9 are complementary to each other to constrain the EoR model parameters such as the minimum virial temperature of halos which host luminous objects, ionizing efficiency, and mean free path of ionizing photons in the IGM. Quantitatively, the constraining power highly depends on the quality of the foreground subtraction and calibration. We give a best case estimate of the constraints on the parameters, neglecting the systematics other than the thermal noise.

  3. Empirical covariance modeling for 21 cm power spectrum estimation: A method demonstration and new limits from early Murchison Widefield Array 128-tile data

    NASA Astrophysics Data System (ADS)

    Dillon, Joshua S.; Neben, Abraham R.; Hewitt, Jacqueline N.; Tegmark, Max; Barry, N.; Beardsley, A. P.; Bowman, J. D.; Briggs, F.; Carroll, P.; de Oliveira-Costa, A.; Ewall-Wice, A.; Feng, L.; Greenhill, L. J.; Hazelton, B. J.; Hernquist, L.; Hurley-Walker, N.; Jacobs, D. C.; Kim, H. S.; Kittiwisit, P.; Lenc, E.; Line, J.; Loeb, A.; McKinley, B.; Mitchell, D. A.; Morales, M. F.; Offringa, A. R.; Paul, S.; Pindor, B.; Pober, J. C.; Procopio, P.; Riding, J.; Sethi, S.; Shankar, N. Udaya; Subrahmanyan, R.; Sullivan, I.; Thyagarajan, Nithyanandan; Tingay, S. J.; Trott, C.; Wayth, R. B.; Webster, R. L.; Wyithe, S.; Bernardi, G.; Cappallo, R. J.; Deshpande, A. A.; Johnston-Hollitt, M.; Kaplan, D. L.; Lonsdale, C. J.; McWhirter, S. R.; Morgan, E.; Oberoi, D.; Ord, S. M.; Prabu, T.; Srivani, K. S.; Williams, A.; Williams, C. L.

    2015-06-01

    The separation of the faint cosmological background signal from bright astrophysical foregrounds remains one of the most daunting challenges of mapping the high-redshift intergalactic medium with the redshifted 21 cm line of neutral hydrogen. Advances in mapping and modeling of diffuse and point source foregrounds have improved subtraction accuracy, but no subtraction scheme is perfect. Precisely quantifying the errors and error correlations due to missubtracted foregrounds allows for both the rigorous analysis of the 21 cm power spectrum and for the maximal isolation of the "EoR window" from foreground contamination. We present a method to infer the covariance of foreground residuals from the data itself in contrast to previous attempts at a priori modeling. We demonstrate our method by setting limits on the power spectrum using a 3 h integration from the 128-tile Murchison Widefield Array. Observing between 167 and 198 MHz, we find at 95% confidence a best limit of Δ2(k )<3.7 ×104 mK2 at comoving scale k =0.18 h Mpc-1 and at z =6.8 , consistent with existing limits.

  4. Heart rate detection from plantar bioimpedance measurements.

    PubMed

    González Landaeta, R; Casas, O; Pallàs-Areny, R

    2006-01-01

    The heart rate is a basic health indicator, useful in both clinical measurements and home health care. Current home care systems often require the attachment of electrodes or other sensors to the body, which can be cumbersome to the patient. Moreover, some measurements are sensitive to movement artifacts, are not user-friendly and require a specialized supervision. In this paper, a novel technique for heart rate measurement for a standing subject is proposed, which is based on plantar bioimpedance measurements, such as those performed by some bathroom weighting scales for body composition analysis. Because of the low level of heart-related impedance variations, the measurement system has a gain of 1400. We have implemented a fully differential AC amplifier with a common-mode rejection ratio (CMRR) of 105 dB at 10 kHz. Coherent demodulation based on synchronous sampling yields a signal-to-noise ratio (SNR) of 55 dB. The system has a sensitivity of 1.9 V/Omega. The technique has been demonstrated on 18 volunteers, whose bioimpedance signal and ECG were simultaneously measured to validate the results. The average cross-correlation coefficient between the heart rates determined from these two signals was 0.998 (std. dev. 0.001). PMID:17946677

  5. From Darkness to Light: Observing the First Stars and Galaxies with the Redshifted 21-cm Line using the Dark Ages Radio Explorer

    NASA Astrophysics Data System (ADS)

    Burns, Jack O.; Lazio, Joseph; Bowman, Judd D.; Bradley, Richard F.; Datta, Abhirup; Furlanetto, Steven; Jones, Dayton L.; Kasper, Justin; Loeb, Abraham; Harker, Geraint

    2015-01-01

    The Dark Ages Radio Explorer (DARE) will reveal when the first stars, black holes, and galaxies formed in the early Universe and will define their characteristics, from the Dark Ages (z=35) to the Cosmic Dawn (z=11). This epoch of the Universe has never been directly observed. The DARE science instrument is composed of electrically-short bi-conical dipole antennas, a correlation receiver, and a digital spectrometer that measures the sky-averaged, low frequency (40-120 MHz) spectral features from the highly redshifted 21-cm HI line that surrounds the first objects. These observations are possible because DARE will orbit the Moon at an altitude of 125 km and takes data when it is above the radio-quiet, ionosphere-free, solar-shielded lunar farside. DARE executes the small-scale mission described in the NASA Astrophysics Roadmap (p. 83): 'mapping the Universe's hydrogen clouds using 21-cm radio wavelengths via lunar orbiter from the farside of the Moon'. This mission will address four key science questions: (1) When did the first stars form and what were their characteristics? (2) When did the first accreting black holes form and what was their characteristic mass? (3) When did reionization begin? (4) What surprises emerged from the Dark Ages (e.g., Dark Matter decay). DARE uniquely complements other major telescopes including Planck, JWST, and ALMA by bridging the gap between the smooth Universe seen via the CMB and rich web of galaxy structures seen with optical/IR/mm telescopes. Support for the development of this mission concept was provided by the Office of the Director, NASA Ames Research Center and by JPL/Caltech.

  6. Detection limit for rate fluctuations in inhomogeneous Poisson processes

    NASA Astrophysics Data System (ADS)

    Shintani, Toshiaki; Shinomoto, Shigeru

    2012-04-01

    Estimations of an underlying rate from data points are inevitably disturbed by the irregular occurrence of events. Proper estimation methods are designed to avoid overfitting by discounting the irregular occurrence of data, and to determine a constant rate from irregular data derived from a constant probability distribution. However, it can occur that rapid or small fluctuations in the underlying density are undetectable when the data are sparse. For an estimation method, the maximum degree of undetectable rate fluctuations is uniquely determined as a phase transition, when considering an infinitely long series of events drawn from a fluctuating density. In this study, we analytically examine an optimized histogram and a Bayesian rate estimator with respect to their detectability of rate fluctuation, and determine whether their detectable-undetectable phase transition points are given by an identical formula defining a degree of fluctuation in an underlying rate. In addition, we numerically examine the variational Bayes hidden Markov model in its detectability of rate fluctuation, and determine whether the numerically obtained transition point is comparable to those of the other two methods. Such consistency among these three principled methods suggests the presence of a theoretical limit for detecting rate fluctuations.

  7. Detection limit for rate fluctuations in inhomogeneous Poisson processes.

    PubMed

    Shintani, Toshiaki; Shinomoto, Shigeru

    2012-04-01

    Estimations of an underlying rate from data points are inevitably disturbed by the irregular occurrence of events. Proper estimation methods are designed to avoid overfitting by discounting the irregular occurrence of data, and to determine a constant rate from irregular data derived from a constant probability distribution. However, it can occur that rapid or small fluctuations in the underlying density are undetectable when the data are sparse. For an estimation method, the maximum degree of undetectable rate fluctuations is uniquely determined as a phase transition, when considering an infinitely long series of events drawn from a fluctuating density. In this study, we analytically examine an optimized histogram and a Bayesian rate estimator with respect to their detectability of rate fluctuation, and determine whether their detectable-undetectable phase transition points are given by an identical formula defining a degree of fluctuation in an underlying rate. In addition, we numerically examine the variational Bayes hidden Markov model in its detectability of rate fluctuation, and determine whether the numerically obtained transition point is comparable to those of the other two methods. Such consistency among these three principled methods suggests the presence of a theoretical limit for detecting rate fluctuations.

  8. Video rate multispectral imaging for camouflaged target detection

    NASA Astrophysics Data System (ADS)

    Henry, Sam

    2015-05-01

    The ability to detect and identify camouflaged targets is critical in combat environments. Hyperspectral and Multispectral cameras allow a soldier to identify threats more effectively than traditional RGB cameras due to both increased color resolution and ability to see beyond visible light. Static imagers have proven successful, however the development of video rate imagers allows for continuous real time target identification and tracking. This paper presents an analysis of existing anomaly detection algorithms and how they can be adopted to video rates, and presents a general purpose semisupervised real time anomaly detection algorithm using multiple frame sampling.

  9. Calculations of rates for direct detection of neutralino dark matter

    SciTech Connect

    Griest, K.

    1988-08-08

    The detection rates in cryogenic detectors of neutralinos, the most well motivated supersymmetric dark-matter candidate, are calculated. These rates can differ greatly from the special cases of pure photoinos and pure Higgsinos which are usually considered. In addition, a new term is found in the elastic-scattering cross section proportional to the Z-ino component which is ''spin independent,'' even for these Majorana particles. As a result, substantial detection rates exist for previously disfavored, mostly spinless materials such as germanium and mercury.

  10. Calculations of rates for direct detection of neutralino dark matter

    NASA Technical Reports Server (NTRS)

    Griest, Kim

    1988-01-01

    The detection rates in cryogenic detectors of neutralinos, the most well motivated supersymmetric dark-matter candidate, are calculated. These rates can differ greatly from the special case of pure photinos and pure Higgsinos which are usually considered. In addition, a new term is found in the elastic-scattering cross section proportional to the Z-ino component which is 'spin independent', even for these Majorana particles. As a result, substantial detection rates exist for previously disfavored, mostly spinless materials such as germanium and mercury.

  11. DOUBLE COMPACT OBJECTS. III. GRAVITATIONAL-WAVE DETECTION RATES

    SciTech Connect

    Dominik, Michal; Belczynski, Krzysztof; Bulik, Tomasz; Berti, Emanuele; O’Shaughnessy, Richard; Mandel, Ilya; Fryer, Christopher; Holz, Daniel E.; Pannarale, Francesco

    2015-06-20

    The unprecedented range of second-generation gravitational-wave (GW) observatories calls for refining the predictions of potential sources and detection rates. The coalescence of double compact objects (DCOs)—i.e., neutron star–neutron star (NS–NS), black hole–neutron star (BH–NS), and black hole–black hole (BH–BH) binary systems—is the most promising source of GWs for these detectors. We compute detection rates of coalescing DCOs in second-generation GW detectors using the latest models for their cosmological evolution, and implementing inspiral-merger-ringdown gravitational waveform models in our signal-to-noise ratio calculations. We find that (1) the inclusion of the merger/ringdown portion of the signal does not significantly affect rates for NS–NS and BH–NS systems, but it boosts rates by a factor of ∼1.5 for BH–BH systems; (2) in almost all of our models BH–BH systems yield by far the largest rates, followed by NS–NS and BH–NS systems, respectively; and (3) a majority of the detectable BH–BH systems were formed in the early universe in low-metallicity environments. We make predictions for the distributions of detected binaries and discuss what the first GW detections will teach us about the astrophysics underlying binary formation and evolution.

  12. Bayesian analysis of energy and count rate data for detection of low count rate radioactive sources.

    PubMed

    Klumpp, John; Brandl, Alexander

    2015-03-01

    A particle counting and detection system is proposed that searches for elevated count rates in multiple energy regions simultaneously. The system analyzes time-interval data (e.g., time between counts), as this was shown to be a more sensitive technique for detecting low count rate sources compared to analyzing counts per unit interval (Luo et al. 2013). Two distinct versions of the detection system are developed. The first is intended for situations in which the sample is fixed and can be measured for an unlimited amount of time. The second version is intended to detect sources that are physically moving relative to the detector, such as a truck moving past a fixed roadside detector or a waste storage facility under an airplane. In both cases, the detection system is expected to be active indefinitely; i.e., it is an online detection system. Both versions of the multi-energy detection systems are compared to their respective gross count rate detection systems in terms of Type I and Type II error rates and sensitivity.

  13. Bayesian analysis of energy and count rate data for detection of low count rate radioactive sources.

    PubMed

    Klumpp, John; Brandl, Alexander

    2015-03-01

    A particle counting and detection system is proposed that searches for elevated count rates in multiple energy regions simultaneously. The system analyzes time-interval data (e.g., time between counts), as this was shown to be a more sensitive technique for detecting low count rate sources compared to analyzing counts per unit interval (Luo et al. 2013). Two distinct versions of the detection system are developed. The first is intended for situations in which the sample is fixed and can be measured for an unlimited amount of time. The second version is intended to detect sources that are physically moving relative to the detector, such as a truck moving past a fixed roadside detector or a waste storage facility under an airplane. In both cases, the detection system is expected to be active indefinitely; i.e., it is an online detection system. Both versions of the multi-energy detection systems are compared to their respective gross count rate detection systems in terms of Type I and Type II error rates and sensitivity. PMID:25627949

  14. Probabilistic pipe fracture evaluations for leak-rate-detection applications

    SciTech Connect

    Rahman, S.; Ghadiali, N.; Paul, D.; Wilkowski, G.

    1995-04-01

    Regulatory Guide 1.45, {open_quotes}Reactor Coolant Pressure Boundary Leakage Detection Systems,{close_quotes} was published by the U.S. Nuclear Regulatory Commission (NRC) in May 1973, and provides guidance on leak detection methods and system requirements for Light Water Reactors. Additionally, leak detection limits are specified in plant Technical Specifications and are different for Boiling Water Reactors (BWRs) and Pressurized Water Reactors (PWRs). These leak detection limits are also used in leak-before-break evaluations performed in accordance with Draft Standard Review Plan, Section 3.6.3, {open_quotes}Leak Before Break Evaluation Procedures{close_quotes} where a margin of 10 on the leak detection limit is used in determining the crack size considered in subsequent fracture analyses. This study was requested by the NRC to: (1) evaluate the conditional failure probability for BWR and PWR piping for pipes that were leaking at the allowable leak detection limit, and (2) evaluate the margin of 10 to determine if it was unnecessarily large. A probabilistic approach was undertaken to conduct fracture evaluations of circumferentially cracked pipes for leak-rate-detection applications. Sixteen nuclear piping systems in BWR and PWR plants were analyzed to evaluate conditional failure probability and effects of crack-morphology variability on the current margins used in leak rate detection for leak-before-break.

  15. Temperature lapse rate as an adjunct to wind shear detection

    NASA Technical Reports Server (NTRS)

    Zweifil, Terry

    1991-01-01

    Several meteorological parameters were examined to determine if measurable atmospheric conditions can improve windshear detection devices. Lapse rate, the temperature change with altitude, shows promise as being an important parameter in the prediction of severe wind shears. It is easily measured from existing aircraft instrumentation, and it can be important indicator of convective activity including thunderstorms and microbursts. The meteorological theory behind lapse rate measurement is briefly reviewed, and and FAA certified system is described that is currently implemented in the Honeywell Wind Shear Detection and Guidance System.

  16. Detecting Seismicity Rate Transients in the Hokkaido Corner

    NASA Astrophysics Data System (ADS)

    Llenos, A. L.; McGuire, J. J.; Ogata, Y.

    2009-12-01

    Transient aseismic processes alter the stress state of a region and can cause seismicity rate anomalies in space and time detectable by models such as the Epidemic Type Aftershock Sequence (ETAS) model (Ogata, 1988). The presence of such anomalies in subduction zones can therefore indicate stress changes are occurring due to processes such as afterslip or slow slip events. The Hokkaido corner in northeastern Japan is a good region to investigate these anomalies and their relationship to frictional conditions on the plate interface. This area consists of several asperities that rupture in great earthquakes such as the 2003 M8.3 Tokachi-oki earthquake. The abundance of high quality seismic and geodetic data for that event have led to the development of detailed coseismic and postseismic slip models (e.g., Yamanaka and Kikuchi, 2003; Miyazaki et al., 2004), from which stress changes can be inferred and compared to spatial and temporal variations in seismicity rate behavior. For example, an analysis of central Japan seismicity suggests that high aftershock productivities tend to cluster on the updip boundaries of major asperities (Ogata, 2005). Elevated stressing rates due to afterslip can also cause increased levels of background seismicity on the fault patches where afterslip is occurring. Therefore, mapping where these anomalies occur can lead to a better understanding of where and how stress is accumulating on the megathrust. We have developed a method that can directly map seismicity rate anomalies to the stressing rate changes due to aseismic processes. Because aftershocks often obscure changes in the background seismicity caused by these processes, we combine two models commonly used to estimate the time dependence of underlying driving mechanisms, the stochastic ETAS model and the physically based rate- and state-dependent friction model (Dieterich, 1994), into a single seismicity rate model that can explain both aftershock activity as well as changes in

  17. SETI Pulse Detection Algorithm: Analysis of False-alarm Rates

    NASA Technical Reports Server (NTRS)

    Levitt, B. K.

    1983-01-01

    Some earlier work by the Search for Extraterrestrial Intelligence (SETI) Science Working Group (SWG) on the derivation of spectrum analyzer thresholds for a pulse detection algorithm based on an analysis of false alarm rates is extended. The algorithm previously analyzed was intended to detect a finite sequence of i periodically spaced pulses that did not necessarily occupy the entire observation interval. This algorithm would recognize the presence of such a signal only if all i-received pulse powers exceeded a threshold T(i): these thresholds were selected to achieve a desired false alarm rate, independent of i. To simplify the analysis, it was assumed that the pulses were synchronous with the spectrum sample times. This analysis extends the earlier effort to include infinite and/or asynchronous pulse trains. Furthermore, to decrease the possibility of missing an extraterrestrial intelligence signal, the algorithm was modified to detect a pulse train even if some of the received pulse powers fall below the threshold. The analysis employs geometrical arguments that make it conceptually easy to incorporate boundary conditions imposed on the derivation of the false alarm rates. While the exact results can be somewhat complex, simple closed form approximations are derived that produce a negligible loss of accuracy.

  18. Experimental evaluation of shark detection rates by aerial observers.

    PubMed

    Robbins, William D; Peddemors, Victor M; Kennelly, Steven J; Ives, Matthew C

    2014-01-01

    Aerial surveys are a recognised technique to identify the presence and abundance of marine animals. However, the capability of aerial observers to reliably sight coastal sharks has not been previously assessed, nor have differences in sighting rates between aircraft types been examined. In this study we investigated the ability of observers in fixed-wing and helicopter aircraft to sight 2.5 m artificial shark analogues placed at known depths and positions. Initial tests revealed that the shark analogues could only be detected at shallow depths, averaging only 2.5 m and 2.7 m below the water surface for observers in fixed-wing and helicopter aircraft, respectively. We then deployed analogues at shallower depths along a 5 km-long grid, and assessed their sightability to aircraft observers through a series of transects flown within 500 m. Analogues were seen infrequently from all distances, with overall sighting rates of only 12.5% and 17.1% for fixed-wing and helicopter observers, respectively. Although helicopter observers had consistently higher success rates of sighting analogues within 250 m of their flight path, neither aircraft observers sighted more than 9% of analogues deployed over 300 m from their flight paths. Modelling of sighting rates against environmental and experimental variables indicated that observations were affected by distance, aircraft type, sun glare and sea conditions, while the range of water turbidities observed had no effect. We conclude that aerial observers have limited ability to detect the presence of submerged animals such as sharks, particularly when the sharks are deeper than ∼ 2.6 m, or over 300 m distant from the aircraft's flight path, especially during sunny or windy days. The low rates of detections found in this study cast serious doubts on the use of aerial beach patrols as an effective early-warning system to prevent shark attacks.

  19. Experimental Evaluation of Shark Detection Rates by Aerial Observers

    PubMed Central

    Robbins, William D.; Peddemors, Victor M.; Kennelly, Steven J.; Ives, Matthew C.

    2014-01-01

    Aerial surveys are a recognised technique to identify the presence and abundance of marine animals. However, the capability of aerial observers to reliably sight coastal sharks has not been previously assessed, nor have differences in sighting rates between aircraft types been examined. In this study we investigated the ability of observers in fixed-wing and helicopter aircraft to sight 2.5 m artificial shark analogues placed at known depths and positions. Initial tests revealed that the shark analogues could only be detected at shallow depths, averaging only 2.5 m and 2.7 m below the water surface for observers in fixed-wing and helicopter aircraft, respectively. We then deployed analogues at shallower depths along a 5 km-long grid, and assessed their sightability to aircraft observers through a series of transects flown within 500 m. Analogues were seen infrequently from all distances, with overall sighting rates of only 12.5% and 17.1% for fixed-wing and helicopter observers, respectively. Although helicopter observers had consistently higher success rates of sighting analogues within 250 m of their flight path, neither aircraft observers sighted more than 9% of analogues deployed over 300 m from their flight paths. Modelling of sighting rates against environmental and experimental variables indicated that observations were affected by distance, aircraft type, sun glare and sea conditions, while the range of water turbidities observed had no effect. We conclude that aerial observers have limited ability to detect the presence of submerged animals such as sharks, particularly when the sharks are deeper than ∼2.6 m, or over 300 m distant from the aircraft's flight path, especially during sunny or windy days. The low rates of detections found in this study cast serious doubts on the use of aerial beach patrols as an effective early-warning system to prevent shark attacks. PMID:24498258

  20. A PC-aided optical foetal heart rate detection system.

    PubMed

    Oweis, Rami J; As'ad, Hala; Aldarawsheh, Amany; Al-Khdeirat, Rawan; Lwissy, Kaldoun

    2014-01-01

    Safe monitoring of foetal heart rate is a valuable tool for the healthy evolution and wellbeing of both foetus and mother. This paper presents a non-invasive optical technique that allows for foetal heart rate detection using a photovoltaic infrared (IR) detector placed on the mother's abdomen. The system presented here consists of a photoplethysmography (PPG) circuit, abdomen circuit and a personal computer equipped with MATLAB. A near IR beam having a wavelength of 880 nm is transmitted through the mother's abdomen and foetal tissue. The received abdominal signal that conveys information pertaining to the mother and foetal heart rate is sensed by a low noise photodetector. The PC receives the signal through the National Instrumentation Data Acquisition Card (NIDAQ). After synchronous detection of the abdominal and finger PPG signals, the designed MATLAB-based software saves, analyses and extracts information related to the foetal heart rate. Extraction is carried out using recursive least squares adaptive filtration. Measurements on eight pregnant women with gestational periods ranging from 35-39 weeks were performed using the proposed system and CTG. Results show a correlation coefficient of 0.978 and a correlation confidence interval between 88-99.6%. The t test results in a p value of 0.034, which is less than 0.05. Low power, low cost, high signal-to-noise ratio, reduction of ambient light effect and ease of use are the main characteristics of the proposed system. PMID:24195701

  1. Motion-compensated non-contact detection of heart rate

    NASA Astrophysics Data System (ADS)

    Yang, Lei; Liu, Ming; Dong, Liquan; Zhao, Yuejin; Liu, Xiaohua

    2015-12-01

    A new non-contact heart rate detection method based on the dual-wavelength technique is proposed and demonstrated experimentally. It is a well-known fact that the differences in the circuits of two detection modules result in different responses of two modules for motion artifacts. This poses a great challenge to compensate the motion artifacts during measurements. In order to circumvent this problem, we have proposed the amplitude spectrum and phase spectrum adaptive filter. Comparing with the time-domain adaptive filter and independent component analysis, the amplitude spectrum and phase spectrum adaptive filter can suppress the interference caused by the two circuit differences and effectively compensate the motion artifacts. To make the device is much compact and portable, a photoelectric probe is designed. The measurement distance is from several centimeters up to several meters. Moreover, the data obtained by using this non-contact detection system is compared with those of the conventional finger blood volume pulse (BVP) sensor by simultaneously measuring the heart rate of the subject. The data obtained from the proposed non-contact system are consistent and comparable with that of the BVP sensor.

  2. Detection of Burst Suppression Patterns in EEG Using Recurrence Rate

    PubMed Central

    Ren, Yongshao; Sleigh, Jamie; Li, Xiaoli

    2014-01-01

    Burst suppression is a unique electroencephalogram (EEG) pattern commonly seen in cases of severely reduced brain activity such as overdose of general anesthesia. It is important to detect burst suppression reliably during the administration of anesthetic or sedative agents, especially for cerebral-protective treatments in various neurosurgical diseases. This study investigates recurrent plot (RP) analysis for the detection of the burst suppression pattern (BSP) in EEG. The RP analysis is applied to EEG data containing BSPs collected from 14 patients. Firstly we obtain the best selection of parameters for RP analysis. Then, the recurrence rate (RR), determinism (DET), and entropy (ENTR) are calculated. Then RR was selected as the best BSP index one-way analysis of variance (ANOVA) and multiple comparison tests. Finally, the performance of RR analysis is compared with spectral analysis, bispectral analysis, approximate entropy, and the nonlinear energy operator (NLEO). ANOVA and multiple comparison tests showed that the RR could detect BSP and that it was superior to other measures with the highest sensitivity of suppression detection (96.49%, P = 0.03). Tracking BSP patterns is essential for clinical monitoring in critically ill and anesthetized patients. The purposed RR may provide an effective burst suppression detector for developing new patient monitoring systems. PMID:24883378

  3. A change detection approach to moving object detection in low frame-rate video

    SciTech Connect

    Porter, Reid B; Harvey, Neal R; Theiler, James P

    2009-01-01

    Moving object detection is of significant interest in temporal image analysis since it is a first step in many object identification and tracking applications. A key component in almost all moving object detection algorithms is a pixel-level classifier, where each pixel is predicted to be either part of a moving object or part of the background. In this paper we investigate a change detection approach to the pixel-level classification problem and evaluate its impact on moving object detection. The change detection approach that we investigate was previously applied to multi-and hyper-spectral datasets, where images were typically taken several days, or months apart. In this paper, we apply the approach to low-frame rate (1-2 frames per second) video datasets.

  4. Ionospheric Modulation of Venus Express Lightning Detection Rates

    NASA Astrophysics Data System (ADS)

    Hart, Richard A.; Russell, Christopher T.; Zhang, Tielong

    2015-11-01

    Venus Express completed its nearly 9 year campaign at Earth’s sister planet in late 2014. During this period the onboard fluxgate magnetometer collected data up to 64 Hz in frequency while near periapsis. This is the expected frequency range for lightning-generated whistler-mode waves at Venus, between the local electron and ion gyrofrequencies. These waves are right-hand circularly polarized and are guided by the local magnetic field. When the Venusian ionopause is low enough in altitude to reside in the collisional region, the interplanetary magnetic field can get carried down with the ions and magnetize the lower ionosphere. As the field travels towards the terminator it gains a radial component, enabling whistlers to reach higher altitudes and be detected by the spacecraft. The mission covered almost an entire solar cycle and frequently observed a magnetized ionosphere during the solar minimum phase when the ionosphere was weak due to reduced incident EUV. Detection was most common at 250 km altitude where the waves travel more slowly due to reduced ionospheric density. In response they increase in amplitude in order to conserve magnetic energy flux. Here, we examine the changes in the ionospheric properties associated with the evolution of the solar cycle and the rate of detection of these lightning-generated signals.

  5. Sleep apnea detection using time-delayed heart rate variability.

    PubMed

    Nano, Marina-Marinela; Xi Long; Werth, Jan; Aarts, Ronald M; Heusdens, Richard

    2015-01-01

    Sleep apnea is a sleep disorder distinguished by repetitive absence of breathing. Compared with the traditional expensive and cumbersome methods, sleep apnea diagnosis or screening with physiological information that can be easily acquired is needed. This paper describes algorithms using heart rate variability (HRV) to automatically detect sleep apneas as long as it can be easily acquired with unobtrusive sensors. Because the changes in cardiac activity are usually hysteretic than the presence of apneas with a few minutes, we propose to use the delayed HRV features to identify the episodes with sleep apneic events. This is expected to help improve the apnea detection performance. Experiments were conducted with a data set of 23 sleep apnea patients using support vector machine (SVM) classifiers and cross validations. Results show that using eleven HRV features with a time delay of 1.5 minutes rather than the features without time delay for SA detection, the overall accuracy increased from 74.9% to 76.2% and the Cohen's Kappa coefficient increased from 0.49 to 0.52. Further, an accuracy of 94.5% and a Kappa of 0.89 were achieved when applying subject-specific classifiers.

  6. Local dynamics of heart rate: detection and prognostic implications.

    PubMed

    Moss, Travis J; Lake, Douglas E; Moorman, J Randall

    2014-10-01

    The original observation that reduced heart rate variability (HRV) confers poor prognosis after myocardial infarction has been followed by many studies of heart rate dynamics. We tested the hypothesis that an entropy-based local dynamics measure gave prognostic information in ambulatory patients undergoing 24-h electrocardiography. In this context, entropy is the probability that short templates will find matches in the time series. We studied RR interval time series from 24-h Holter monitors of 1564 consecutive patients over age 39. We generated histograms of the count of templates as a function of the number of templates matches in short RR interval time series, and found characteristic appearance of histograms for atrial fibrillation, sinus rhythm with normal HRV, and sinus rhythm with reduced HRV and premature ventricular contractions (PVCs). We developed statistical models to detect the abnormal dynamic phenotype of reduced HRV with PVCs and fashioned a local dynamics score (LDs) that, after controlling for age, added more prognostic information than other standard risk factors and common HRV metrics, including, to our surprise, the PVC count and the HRV of normal-to-normal intervals. Addition of the LDs to a predictive model using standard risk factors significantly increased the ROC area and the net reclassification improvement was 27%. We conclude that abnormal local dynamics of heart rate confer adverse prognosis in patients undergoing 24-h ambulatory electrocardiography.

  7. A coincidence detection algorithm for improving detection rates in coulomb explosion imaging

    NASA Astrophysics Data System (ADS)

    Wales, Benji; Bisson, Eric; Karimi, Reza; Kieffer, Jean-Claude; Légaré, Francois; Sanderson, Joseph

    2012-03-01

    A scheme for determining true coincidence events in Coulomb Explosion Imaging experiments is reported and compared with a simple design used in recently published work. The new scheme is able to identify any possible coincidence without the use of a priori knowledge of the fragmentation mechanism. Using experimental data from the triatomic molecule OCS, the advanced algorithm is shown to improve acquisition yield by a factor of between 2 and 6 depending on the amount of a priori knowledge included in the simple design search. Monte Carlo simulations for both systems suggest that detection yield can be improved by increasing the number of molecules in the laser focus from the standard ≤1 up to 3.5 and employing the advanced algorithm. Count rates for larger molecules would be preferentially improved with the rate for 6 atom molecules improved by a factor of up to five.

  8. Gait event detection during stair walking using a rate gyroscope.

    PubMed

    Formento, Paola Catalfamo; Acevedo, Ruben; Ghoussayni, Salim; Ewins, David

    2014-03-19

    Gyroscopes have been proposed as sensors for ambulatory gait analysis and functional electrical stimulation systems. These applications often require detection of the initial contact (IC) of the foot with the floor and/or final contact or foot off (FO) from the floor during outdoor walking. Previous investigations have reported the use of a single gyroscope placed on the shank for detection of IC and FO on level ground and incline walking. This paper describes the evaluation of a gyroscope placed on the shank for determination of IC and FO in subjects ascending and descending a set of stairs. Performance was compared with a reference pressure measurement system. The absolute mean difference between the gyroscope and the reference was less than 45 ms for IC and better than 135 ms for FO for both activities. Detection success was over 93%. These results provide preliminary evidence supporting the use of a gyroscope for gait event detection when walking up and down stairs.

  9. Gait Event Detection during Stair Walking Using a Rate Gyroscope

    PubMed Central

    Formento, Paola Catalfamo; Acevedo, Ruben; Ghoussayni, Salim; Ewins, David

    2014-01-01

    Gyroscopes have been proposed as sensors for ambulatory gait analysis and functional electrical stimulation systems. These applications often require detection of the initial contact (IC) of the foot with the floor and/or final contact or foot off (FO) from the floor during outdoor walking. Previous investigations have reported the use of a single gyroscope placed on the shank for detection of IC and FO on level ground and incline walking. This paper describes the evaluation of a gyroscope placed on the shank for determination of IC and FO in subjects ascending and descending a set of stairs. Performance was compared with a reference pressure measurement system. The absolute mean difference between the gyroscope and the reference was less than 45 ms for IC and better than 135 ms for FO for both activities. Detection success was over 93%. These results provide preliminary evidence supporting the use of a gyroscope for gait event detection when walking up and down stairs. PMID:24651724

  10. Noninvasive detection of gas exchange rate by near infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Xu, Guodong; Mao, Zongzhen; Wang, Bangde

    2008-12-01

    In order to study the relationship among the oxygen concentration in skeletal muscle tissues and the heart rate (HR), oxygen uptake (VO2), respiratory exchange ratio (RER) during incremental running exercises on a treadmill, a near-infrared spectroscopy muscle oxygen monitor system is employed to measure the relative change in muscle oxygenation, with the heart rate, oxygen uptake, production of carbon dioxide (VCO2) and respiratory exchange ratio are recorded synchronously. The results indicate parameters mentioned above present regular changes during the incremental exercise. High correlations are discovered between relative change of oxy-hemoglobin concentration and heart rate, oxygen uptake, respiratory exchange ratio at the significance level (P=0.01). This research might introduce a new measurement technology and/or a novel biological monitoring parameter to the evaluation of physical function status, control the training intensity, estimation of the effectiveness of exercise. Keywords: near-infrared spectroscopy; muscle oxygen concentration; heart rate; oxygen uptake; respiratory exchange ratio.

  11. Ambulatory respiratory rate detection using ECG and a triaxial accelerometer.

    PubMed

    Chan, Alexander M; Ferdosi, Nima; Narasimhan, Ravi

    2013-01-01

    Continuous monitoring of respiratory rate in ambulatory conditions has widespread applications for screening of respiratory diseases and remote patient monitoring. Unfortunately, minimally obtrusive techniques often suffer from low accuracy. In this paper, we describe an algorithm with low computational complexity for combining multiple respiratory measurements to estimate breathing rate from an unobtrusive chest patch sensor. Respiratory rates derived from the respiratory sinus arrhythmia (RSA) and modulation of the QRS amplitude of electrocardiography (ECG) are combined with a respiratory rate derived from tri-axial accelerometer data. The three respiration rates are combined by a weighted average using weights based on quality metrics for each signal. The algorithm was evaluated on 15 elderly subjects who performed spontaneous and metronome breathing as well as a variety of activities of daily living (ADLs). When compared to a reference device, the mean absolute error was 1.02 breaths per minute (BrPM) during metronome breathing, 1.67 BrPM during spontaneous breathing, and 2.03 BrPM during ADLs.

  12. Aid to determining freeway metering rates and detecting loop errors

    SciTech Connect

    Nihan, N.L.

    1997-11-01

    A recent freeway congestion prediction study for the Washington Department of Transportation (WSDOT) found that the sum of storage rates over time, SumSR(t), for a freeway section was a better variable for determining the best upstream ramp metering rates than the storage rate for time interval t, SR(t), which is the current WSDOT criterion. (Use of the SumSR(t) variable for this purpose requires that the summation be started during a period of low density flows.) Another finding was that the SumSR(t) variable was a better detector of loop chattering errors than WSDOT`s current criterion, which misses chattering errors that occur at normal traffic volume levels. Since calculation of SumSR(t) is easily incorporated in the current WSDOT ramp metering algorithm, the writer recommends its use in future WSDOT freeway metering schemes.

  13. Cardiac rate detection method based on the beam splitter prism

    NASA Astrophysics Data System (ADS)

    Yang, Lei; Liu, Xiaohua; Liu, Ming; Zhao, Yuejin; Dong, Liquan; Zhao, Ruirui; Jin, Xiaoli; Zhao, Jingsheng

    2013-09-01

    A new cardiac rate measurement method is proposed. Through the beam splitter prism, the common-path optical system of transmitting and receiving signals is achieved. By the focusing effect of the lens, the small amplitude motion artifact is inhibited and the signal-to-noise is improved. The cardiac rate is obtained based on the PhotoPlethysmoGraphy (PPG). We use LED as the light source and use photoelectric diode as the receiving tube. The LED and the photoelectric diode are on the different sides of the beam splitter prism and they form the optical system. The signal processing and display unit is composed by the signal processing circuit, data acquisition device and computer. The light emitted by the modulated LED is collimated by the lens and irradiates the measurement target through the beam splitter prism. The light reflected by the target is focused on the receiving tube through the beam splitter prism and another lens. The signal received by the photoelectric diode is processed by the analog circuit and obtained by the data acquisition device. Through the filtering and Fast Fourier Transform, the cardiac rate is achieved. We get the real time cardiac rate by the moving average method. We experiment with 30 volunteers, containing different genders and different ages. We compare the signals captured by this method to a conventional PPG signal captured concurrently from a finger. The results of the experiments are all relatively agreeable and the biggest deviation value is about 2bmp.

  14. Spectral photoplethysmographic imaging sensor fusion for enhanced heart rate detection

    NASA Astrophysics Data System (ADS)

    Amelard, Robert; Clausi, David A.; Wong, Alexander

    2016-03-01

    Continuous heart rate monitoring can provide important context for quantitative clinical assessment in scenarios such as long-term health monitoring and disability prevention. Photoplethysmographic imaging (PPGI) systems are particularly useful for such monitoring scenarios as contact-based devices pose problems related to comfort and mobility. Each pixel can be regarded as a virtual PPG sensor, thus enabling simultaneous measurements of multiple skin sites. Existing PPGI systems analyze temporal PPGI sensor uctuations related to hemodynamic pulsations across a region of interest to extract the blood pulse signal. However, due to spatially varying optical properties of the skin, the blood pulse signal may not be consistent across all PPGI sensors, leading to inaccurate heart rate monitoring. To increase the hemodynamic signal-to-noise ratio (SNR), we propose a novel spectral PPGI sensor fusion method for enhanced estimation of the true blood pulse signal. Motivated by the observation that PPGI sensors with high hemodynamic SNR exhibit a spectral energy peak at the heart rate frequency, an entropy-based fusion model was formulated to combine PPGI sensors based on the sensors' spectral energy distribution. The optical PPGI device comprised a near infrared (NIR) sensitive camera and an 850 nm LED. Spatially uniform irradiance was achieved by placing optical elements along the LED beam, providing consistent illumination across the skin area. Dual-mode temporally coded illumination was used to negate the temporal effect of ambient illumination. Experimental results show that the spectrally weighted PPGI method can accurately and consistently extract heart rate information where traditional region-based averaging fails.

  15. Using a Calculated Pulse Rate with an Artificial Neural Network to Detect Irregular Interbeats.

    PubMed

    Yeh, Bih-Chyun; Lin, Wen-Piao

    2016-03-01

    Heart rate is an important clinical measure that is often used in pathological diagnosis and prognosis. Valid detection of irregular heartbeats is crucial in the clinical practice. We propose an artificial neural network using the calculated pulse rate to detect irregular interbeats. The proposed system measures the calculated pulse rate to determine an "irregular interbeat on" or "irregular interbeat off" event. If an irregular interbeat is detected, the proposed system produces a danger warning, which is helpful for clinicians. If a non-irregular interbeat is detected, the proposed system displays the calculated pulse rate. We include a flow chart of the proposed software. In an experiment, we measure the calculated pulse rates and achieve an error percentage of < 3% in 20 participants with a wide age range. When we use the calculated pulse rates to detect irregular interbeats, we find such irregular interbeats in eight participants. PMID:26643078

  16. Comparison of heart rate variability and pulse rate variability detected with photoplethysmography

    NASA Astrophysics Data System (ADS)

    Rauh, Robert; Limley, Robert; Bauer, Rainer-Dieter; Radespiel-Troger, Martin; Mueck-Weymann, Michael

    2004-08-01

    This study compares ear photoplethysmography (PPG) and electrocardiogram (ECG) in providing accurate heart beat intervals for use in calculations of heart rate variability (HRV, from ECG) or of pulse rate variability (PRV, from PPG) respectively. Simultaneous measurements were taken from 44 healthy subjects at rest during spontaneous breathing and during forced metronomic breathing (6/min). Under both conditions, highly significant (p > 0.001) correlations (1.0 > r > 0.97) were found between all evaluated common HRV and PRV parameters. However, under both conditions the PRV parameters were higher than HRV. In addition, we calculated the limits of agreement according to Bland and Altman between both techniques and found good agreement (< 10% difference) for heart rate and standard deviation of normal-to-normal intervals (SDNN), but only moderate (10-20%) or even insufficient (> 20%) agreement for other standard HRV and PRV parameters. Thus, PRV data seem to be acceptable for screening purposes but, at least at this state of knowledge, not for medical decision making. However, further studies are needed before more certain determination can be made.

  17. THE GEOMETRY EFFECTS OF AN EXPANDING UNIVERSE ON THE DETECTION OF COOL NEUTRAL GAS AT HIGH REDSHIFT

    SciTech Connect

    Curran, S. J.

    2012-03-20

    Recent high-redshift surveys for 21 cm absorption in damped Ly{alpha} absorption systems (DLAs) take the number of published searches at z{sub abs} > 2 to 25, the same number as at z{sub abs} < 2, although the detection rate at high redshift remains significantly lower (20% compared to 60%). Using the known properties of the DLAs to estimate the unknown profile widths of the 21 cm non-detections and including the limits via a survival analysis, we show that the mean spin temperature/covering factor degeneracy at high redshift is, on average, double that of the low-redshift sample. This value is significantly lower than the previous factor of eight for the spin temperatures and is about the same factor as in the angular diameter distance ratios between the low- and high-redshift samples. That is, without the need for the several pivotal assumptions, which lead to an evolution in the spin temperature, we show that the observed distribution of 21 cm detections in DLAs can be accounted for by the geometry effects of an expanding universe. That is, as yet there is no evidence of the spin temperature of gas-rich galaxies evolving with redshift.

  18. Detection rates of the MODIS active fire product in the United States

    USGS Publications Warehouse

    Hawbaker, T.J.; Radeloff, V.C.; Syphard, A.D.; Zhu, Z.; Stewart, S.I.

    2008-01-01

    MODIS active fire data offer new information about global fire patterns. However, uncertainties in detection rates can render satellite-derived fire statistics difficult to interpret. We evaluated the MODIS 1??km daily active fire product to quantify detection rates for both Terra and Aqua MODIS sensors, examined how cloud cover and fire size affected detection rates, and estimated how detection rates varied across the United States. MODIS active fire detections were compared to 361 reference fires (??? 18??ha) that had been delineated using pre- and post-fire Landsat imagery. Reference fires were considered detected if at least one MODIS active fire pixel occurred within 1??km of the edge of the fire. When active fire data from both Aqua and Terra were combined, 82% of all reference fires were found, but detection rates were less for Aqua and Terra individually (73% and 66% respectively). Fires not detected generally had more cloudy days, but not when the Aqua data were considered exclusively. MODIS detection rates decreased with fire size, and the size at which 50% of all fires were detected was 105??ha when combining Aqua and Terra (195??ha for Aqua and 334??ha for Terra alone). Across the United States, detection rates were greatest in the West, lower in the Great Plains, and lowest in the East. The MODIS active fire product captures large fires in the U.S. well, but may under-represent fires in areas with frequent cloud cover or rapidly burning, small, and low-intensity fires. We recommend that users of the MODIS active fire data perform individual validations to ensure that all relevant fires are included. ?? 2008 Elsevier Inc. All rights reserved.

  19. Persistence rates and detection probabilities of oiled king eider carcasses on St Paul Island, Alaska

    USGS Publications Warehouse

    Fowler, A.C.; Flint, P.L.

    1997-01-01

    Following an oil spill off St Paul Island, Alaska in February 1996, persistence rates and detection probabilities of oiled king eider (Somateria spectabilis) carcasses were estimated using the Cormack-Jolly-Seber model. Carcass persistence rates varied by day, beach type and sex, while detection probabilities varied by day and beach type. Scavenging, wave action and weather influenced carcass persistence. The patterns of persistence differed on rock and sand beaches and female carcasses had a different persistence function than males. Weather, primarily snow storms, and degree of carcass scavenging, diminished carcass detectability. Detection probabilities on rock beaches were lower and more variable than on sand beaches. The combination of persistence rates and detection probabilities can be used to improve techniques of estimating total mortality.

  20. Highly accurate moving object detection in variable bit rate video-based traffic monitoring systems.

    PubMed

    Huang, Shih-Chia; Chen, Bo-Hao

    2013-12-01

    Automated motion detection, which segments moving objects from video streams, is the key technology of intelligent transportation systems for traffic management. Traffic surveillance systems use video communication over real-world networks with limited bandwidth, which frequently suffers because of either network congestion or unstable bandwidth. Evidence supporting these problems abounds in publications about wireless video communication. Thus, to effectively perform the arduous task of motion detection over a network with unstable bandwidth, a process by which bit-rate is allocated to match the available network bandwidth is necessitated. This process is accomplished by the rate control scheme. This paper presents a new motion detection approach that is based on the cerebellar-model-articulation-controller (CMAC) through artificial neural networks to completely and accurately detect moving objects in both high and low bit-rate video streams. The proposed approach is consisted of a probabilistic background generation (PBG) module and a moving object detection (MOD) module. To ensure that the properties of variable bit-rate video streams are accommodated, the proposed PBG module effectively produces a probabilistic background model through an unsupervised learning process over variable bit-rate video streams. Next, the MOD module, which is based on the CMAC network, completely and accurately detects moving objects in both low and high bit-rate video streams by implementing two procedures: 1) a block selection procedure and 2) an object detection procedure. The detection results show that our proposed approach is capable of performing with higher efficacy when compared with the results produced by other state-of-the-art approaches in variable bit-rate video streams over real-world limited bandwidth networks. Both qualitative and quantitative evaluations support this claim; for instance, the proposed approach achieves Similarity and F1 accuracy rates that are 76

  1. Highly accurate moving object detection in variable bit rate video-based traffic monitoring systems.

    PubMed

    Huang, Shih-Chia; Chen, Bo-Hao

    2013-12-01

    Automated motion detection, which segments moving objects from video streams, is the key technology of intelligent transportation systems for traffic management. Traffic surveillance systems use video communication over real-world networks with limited bandwidth, which frequently suffers because of either network congestion or unstable bandwidth. Evidence supporting these problems abounds in publications about wireless video communication. Thus, to effectively perform the arduous task of motion detection over a network with unstable bandwidth, a process by which bit-rate is allocated to match the available network bandwidth is necessitated. This process is accomplished by the rate control scheme. This paper presents a new motion detection approach that is based on the cerebellar-model-articulation-controller (CMAC) through artificial neural networks to completely and accurately detect moving objects in both high and low bit-rate video streams. The proposed approach is consisted of a probabilistic background generation (PBG) module and a moving object detection (MOD) module. To ensure that the properties of variable bit-rate video streams are accommodated, the proposed PBG module effectively produces a probabilistic background model through an unsupervised learning process over variable bit-rate video streams. Next, the MOD module, which is based on the CMAC network, completely and accurately detects moving objects in both low and high bit-rate video streams by implementing two procedures: 1) a block selection procedure and 2) an object detection procedure. The detection results show that our proposed approach is capable of performing with higher efficacy when compared with the results produced by other state-of-the-art approaches in variable bit-rate video streams over real-world limited bandwidth networks. Both qualitative and quantitative evaluations support this claim; for instance, the proposed approach achieves Similarity and F1 accuracy rates that are 76

  2. Can Sample-Specific Simulations Help Detect Low Base-Rate Taxonicity?

    ERIC Educational Resources Information Center

    Beach, Steven R. H.; Amir, Nader; Bau, Jinn Jonp

    2005-01-01

    The authors examined the role of the sample-specific simulations (SSS; A. M. Ruscio & J. Ruscio, 2002; J. Ruscio & A. M. Ruscio, 2004) procedure in detecting low base-rate taxa that might otherwise prove elusive. The procedure preserved key distributional characteristics for moderate to high base-rate taxa, but it performed inadequately for low…

  3. Detection Rates for Surveys for Fast Transients with Next Generation Radio Arrays

    NASA Astrophysics Data System (ADS)

    Macquart, Jean-Pierre

    2011-06-01

    We relate the underlying properties of a population of fast radio-emitting transient events to its expected detection rate in a survey of finite sensitivity. The distribution of the distances of the detected events is determined in terms of the population luminosity distribution and survey parameters, for both extragalactic and Galactic populations. The detection rate as a function of Galactic position is examined to identify regions that optimize survey efficiency in a survey whose field of view is limited. The impact of temporal smearing caused by scattering in the interstellar medium has a large and direction-dependent bearing on the detection of impulsive signals, and we present a model for the effects of scattering on the detection rate. We show that the detection rate scales as ΩS -3/2 + δ 0, where Ω is the field of view, S 0 is the minimum detectable flux density, and 0 < δ <= 3/2 for a survey of Galactic transients in which interstellar scattering or the finite volume of the Galaxy is important. We derive formal conditions on the optimal survey strategy to adopt under different circumstances for fast transient surveys on next generation large-element, wide-field arrays, such as ASKAP, LOFAR, the MWA, and the SKA, and show how interstellar scattering and the finite spatial extent of a Galactic population modify the choice of optimal strategy.

  4. A Novel Microfluidic Flow Rate Detection Method Based on Surface Plasmon Resonance Temperature Imaging

    PubMed Central

    Deng, Shijie; Wang, Peng; Liu, Shengnan; Zhao, Tianze; Xu, Shanzhi; Guo, Mingjiang; Yu, Xinglong

    2016-01-01

    A novel microfluidic flow rate detection method based on surface plasmon resonance (SPR) temperature imaging is proposed. The measurement is performed by space-resolved SPR imaging of the flow induced temperature variations. Theoretical simulations and analysis were performed to demonstrate a proof of concept using this approach. Experiments were implemented and results showed that water flow rates within a wide range of tens to hundreds of μL/min could be detected. The flow rate sensor is resistant to disturbances and can be easily integrated into microfluidic lab-on-chip systems. PMID:27347960

  5. Existence detection and embedding rate estimation of blended speech in covert speech communications.

    PubMed

    Li, Lijuan; Gao, Yong

    2016-01-01

    Covert speech communications may be used by terrorists to commit crimes through Internet. Steganalysis aims to detect secret information in covert communications to prevent crimes. Herein, based on the average zero crossing rate of the odd-even difference (AZCR-OED), a steganalysis algorithm for blended speech is proposed; it can detect the existence and estimate the embedding rate of blended speech. First, the odd-even difference (OED) of the speech signal is calculated and divided into frames. The average zero crossing rate (ZCR) is calculated for each OED frame, and the minimum average ZCR and AZCR-OED of the entire speech signal are extracted as features. Then, a support vector machine classifier is used to determine whether the speech signal is blended. Finally, a voice activity detection algorithm is applied to determine the hidden location of the secret speech and estimate the embedding rate. The results demonstrate that without attack, the detection accuracy can reach 80 % or more when the embedding rate is greater than 10 %, and the estimated embedding rate is similar to the real value. And when some attacks occur, it can also reach relatively high detection accuracy. The algorithm has high performance in terms of accuracy, effectiveness and robustness. PMID:27462497

  6. Cancer detection rates of different prostate biopsy regimens in patients with renal failure.

    PubMed

    Hoşcan, Mustafa Burak; Özorak, Alper; Oksay, Taylan; Perk, Hakkı; Armağan, Abdullah; Soyupek, Sedat; Serel, Tekin Ahmet; Koşar, Alim

    2014-07-01

    We aimed to evaluate the cancer detection rates of 6-, 10-, 12-core biopsy regimens and the optimal biopsy protocol for prostate cancer diagnosis in patients with renal failure. A total of 122 consecutive patients with renal failure underwent biopsy with age-specific prostate-specific antigen (PSA) levels up to 20 ng/mL. The 12-core biopsy technique (sextant biopsy + lateral base, lateral mid-zone, lateral apex, bilaterally) performed to all patients. Pathology results were examined separately for each sextant, 10-core that exclude parasagittal mid-zones from 12-cores (10a), 10-core that exclude apex zones from 12-cores (10b) and 12-core biopsy regimens. Of 122 patients, 37 (30.3%) were positive for prostate cancer. The cancer detection rates for sextant, 10a, 10b and 12 cores were 17.2%, 29%, 23.7% and 30.7%, respectively. Biopsy techniques of 10a, 10b and 12 cores increased the cancer detection rates by 40%, 27.5% and 43.2% among the sextant technique, respectively. Biopsy techniques of 10a and 12 cores increased the cancer detection rates by 17.1% and 21.6% among 10b biopsy technique, respectively. There were no statistical differences between 12 core and 10a core about cancer detection rate. Adding lateral cores to sextant biopsy improves the cancer detection rates. In our study, 12-core biopsy technique increases the cancer detection rate by 5.4% among 10a core but that was not statistically different. On the other hand, 12-core biopsy technique includes all biopsy regimens. We therefore suggest 12-core biopsy or minimum 10-core strategy incorporating six peripheral biopsies with elevated age- specific PSA levels up to 20 ng/mL in patients with renal failure. PMID:24797801

  7. Cancer detection rates of different prostate biopsy regimens in patients with renal failure.

    PubMed

    Hoşcan, Mustafa Burak; Özorak, Alper; Oksay, Taylan; Perk, Hakkı; Armağan, Abdullah; Soyupek, Sedat; Serel, Tekin Ahmet; Koşar, Alim

    2014-07-01

    We aimed to evaluate the cancer detection rates of 6-, 10-, 12-core biopsy regimens and the optimal biopsy protocol for prostate cancer diagnosis in patients with renal failure. A total of 122 consecutive patients with renal failure underwent biopsy with age-specific prostate-specific antigen (PSA) levels up to 20 ng/mL. The 12-core biopsy technique (sextant biopsy + lateral base, lateral mid-zone, lateral apex, bilaterally) performed to all patients. Pathology results were examined separately for each sextant, 10-core that exclude parasagittal mid-zones from 12-cores (10a), 10-core that exclude apex zones from 12-cores (10b) and 12-core biopsy regimens. Of 122 patients, 37 (30.3%) were positive for prostate cancer. The cancer detection rates for sextant, 10a, 10b and 12 cores were 17.2%, 29%, 23.7% and 30.7%, respectively. Biopsy techniques of 10a, 10b and 12 cores increased the cancer detection rates by 40%, 27.5% and 43.2% among the sextant technique, respectively. Biopsy techniques of 10a and 12 cores increased the cancer detection rates by 17.1% and 21.6% among 10b biopsy technique, respectively. There were no statistical differences between 12 core and 10a core about cancer detection rate. Adding lateral cores to sextant biopsy improves the cancer detection rates. In our study, 12-core biopsy technique increases the cancer detection rate by 5.4% among 10a core but that was not statistically different. On the other hand, 12-core biopsy technique includes all biopsy regimens. We therefore suggest 12-core biopsy or minimum 10-core strategy incorporating six peripheral biopsies with elevated age- specific PSA levels up to 20 ng/mL in patients with renal failure.

  8. Modulation rate detection and discrimination by normal-hearing and hearing-impaired listeners.

    PubMed

    Grant, K W; Summers, V; Leek, M R

    1998-08-01

    Modulation detection and modulation rate discrimination thresholds were obtained at three different modulation rates (fm = 80, 160, and 320 Hz) and for three different ranges of modulation depths (m): full (100%), mid (70%-80%), and low (40%-60%) with both normal-hearing (NH) and hearing-impaired (HI) subjects. The results showed that modulation detection thresholds increased with modulation rate, but significantly more so for HI than for NH subjects. Similarly, rate discrimination thresholds (delta r) increased with increases in fm and decreases in modulation depth. When compared to NH subjects, rate discrimination thresholds for HI subjects were significantly worse for all rates and for all depths. At the fastest modulation rate with less than 100% modulation depth, most HI subjects could not discriminate any change in rate. When valid thresholds for rate discrimination were obtained for HI subjects, they ranged from 2.5 semitones (delta r = 12.7 Hz, fm = 80 Hz, m = 100%) to 8.7 semitones (delta r = 214.5 Hz, fm = 320 Hz, m = 100%). In contrast, average rate discrimination thresholds for NH subjects ranged from 0.9 semitones (delta r = 4.2 Hz, fm = 80 Hz, m = 100%) to 4.7 semitones (delta r = 103.5 Hz, fm = 320 Hz, m = 60%). Some of the differences in temporal processing between NH and HI subjects, especially those related to modulation detection, may be accounted for by differences in signal audibility, especially for high-frequency portions of the modulated noise. However, in many cases, HI subjects encountered great difficulty discriminating a change in modulation rate even though the modulation components of the standard and test stimuli were detectable.

  9. The Impact of Colonoscopy Quality Control Table on Adenoma Detection Rates

    PubMed Central

    Deng, Bin; Zhi, Jiehua; Chen, Yaosheng; Liang, Lanyu; Wu, Jian; Gao, Xuefen; Xiao, Weiming; Ding, Yanbing

    2016-01-01

    Objective. This study aims to investigate the effects of reporting colonoscopy findings and the regular review of outcomes on adenoma detection rates. Methods. Patients who underwent colonoscopy from August 2013 to February 2014 were selected as the intervention group. The preintervention group included patients who underwent colonoscopy from January 2013 to July 2013, in which the procedure sheet for this group of patients was not accomplished. The primary outcome was adenoma detection rate (ADR), and secondary outcomes included the success rate of intubation and withdrawal time. Results. This study included 2,467 cases: 1,302 cases in the intervention group and 1,165 cases in the preintervention group. There was no significant difference in demographic characteristics between the two groups. In the intervention group, withdrawal time of colonoscopy was longer (P < 0.01), and the success rate of intubation (92.5% versus 89.1%, P < 0.05) and detection rate of polyps (32.6% versus 27.6%, P < 0.05) and adenomas (20.0% versus 16.1%, P < 0.05) were higher. Significantly high detection rates for proximal adenomas, flat adenomas, and adenomas with a diameter <5 mm were observed in the intervention group (all P < 0.01). Conclusion. The reporting and review of procedure details help to improve quality indicators of colonoscopy. PMID:27340398

  10. Rate discrimination, gap detection and ranking of temporal pitch in cochlear implant users.

    PubMed

    Cosentino, Stefano; Carlyon, Robert P; Deeks, John M; Parkinson, Wendy; Bierer, Julie A

    2016-08-01

    Cochlear implant (CI) users have poor temporal pitch perception, as revealed by two key outcomes of rate discrimination tests: (i) rate discrimination thresholds (RDTs) are typically larger than the corresponding frequency difference limen for pure tones in normal hearing listeners, and (ii) above a few hundred pulses per second (i.e. the "upper limit" of pitch), CI users cannot discriminate further increases in pulse rate. Both RDTs at low rates and the upper limit of pitch vary across listeners and across electrodes in a given listener. Here, we compare across-electrode and across-subject variation in these two measures with the variation in performance on another temporal processing task, gap detection, in order to explore the limitations of temporal processing in CI users. RDTs were obtained for 4-5 electrodes in each of 10 Advanced Bionics CI users using two interleaved adaptive tracks, corresponding to standard rates of 100 and 400 pps. Gap detection was measured using the adaptive procedure and stimuli described by Bierer et al. (JARO 16:273-284, 2015), and for the same electrodes and listeners as for the rate discrimination measures. Pitch ranking was also performed using a mid-point comparison technique. There was a marginal across-electrode correlation between gap detection and rate discrimination at 400 pps, but neither measure correlated with rate discrimination at 100 pps. Similarly, there was a highly significant across-subject correlation between gap detection and rate discrimination at 400, but not 100 pps, and these two correlations differed significantly from each other. Estimates of low-rate sensitivity and of the upper limit of pitch, obtained from the pitch ranking experiment, correlated well with rate discrimination for the 100- and 400-pps standards, respectively. The results are consistent with the upper limit of rate discrimination sharing a common basis with gap detection. There was no evidence that this limitation also applied to rate

  11. A double-observer method to estimate detection rate during aerial waterfowl surveys

    USGS Publications Warehouse

    Koneff, M.D.; Royle, J. Andrew; Otto, M.C.; Wortham, J.S.; Bidwell, J.K.

    2008-01-01

    We evaluated double-observer methods for aerial surveys as a means to adjust counts of waterfowl for incomplete detection. We conducted our study in eastern Canada and the northeast United States utilizing 3 aerial-survey crews flying 3 different types of fixed-wing aircraft. We reconciled counts of front- and rear-seat observers immediately following an observation by the rear-seat observer (i.e., on-the-fly reconciliation). We evaluated 6 a priori models containing a combination of several factors thought to influence detection probability including observer, seat position, aircraft type, and group size. We analyzed data for American black ducks (Anas rubripes) and mallards (A. platyrhynchos), which are among the most abundant duck species in this region. The best-supported model for both black ducks and mallards included observer effects. Sample sizes of black ducks were sufficient to estimate observer-specific detection rates for each crew. Estimated detection rates for black ducks were 0.62 (SE = 0.10), 0.63 (SE = 0.06), and 0.74 (SE = 0.07) for pilot-observers, 0.61 (SE = 0.08), 0.62 (SE = 0.06), and 0.81 (SE = 0.07) for other front-seat observers, and 0.43 (SE = 0.05), 0.58 (SE = 0.06), and 0.73 (SE = 0.04) for rear-seat observers. For mallards, sample sizes were adequate to generate stable maximum-likelihood estimates of observer-specific detection rates for only one aerial crew. Estimated observer-specific detection rates for that crew were 0.84 (SE = 0.04) for the pilot-observer, 0.74 (SE = 0.05) for the other front-seat observer, and 0.47 (SE = 0.03) for the rear-seat observer. Estimated observer detection rates were confounded by the position of the seat occupied by an observer, because observers did not switch seats, and by land-cover because vegetation and landform varied among crew areas. Double-observer methods with on-the-fly reconciliation, although not without challenges, offer one viable option to account for detection bias in aerial waterfowl

  12. Parametric study of antennas for long range Doppler radar heart rate detection.

    PubMed

    Baboli, Mehran; Singh, Aditya; Hafner, Noah; Lubecke, Victor

    2012-01-01

    This research presents results obtained from long range measurements of physiological motion pertaining to human cardiac and respiration activity. A pulse pressure sensor was used as reference to verify the results from radar signals. A motion detection and grading algorithm was used to detect the presence of heart rate. In addition to showing that human heart rate and respiration can be measured at distances of 21 and 69 meters respectively, the effect of antenna size, radiation pattern and gain on the range of the radar has also been studied.

  13. Parametric study of antennas for long range Doppler radar heart rate detection.

    PubMed

    Baboli, Mehran; Singh, Aditya; Hafner, Noah; Lubecke, Victor

    2012-01-01

    This research presents results obtained from long range measurements of physiological motion pertaining to human cardiac and respiration activity. A pulse pressure sensor was used as reference to verify the results from radar signals. A motion detection and grading algorithm was used to detect the presence of heart rate. In addition to showing that human heart rate and respiration can be measured at distances of 21 and 69 meters respectively, the effect of antenna size, radiation pattern and gain on the range of the radar has also been studied. PMID:23366747

  14. Field Intensity Detection of Individual Terahertz Pulses at 80 MHz Repetition Rate

    NASA Astrophysics Data System (ADS)

    Rettich, F.; Vieweg, N.; Cojocari, O.; Deninger, A.

    2015-07-01

    We present a new approach to detect the intensity of individual terahertz pulses at repetition rates as high as 80 MHz. Our setup comprises a femtosecond fiber laser, an InGaAs-based terahertz emitter, a zero-bias Schottky detector, and a high-speed data acquisition unit. The detected pulses consist of two lobes with half-widths of 1-2 ns, which is much shorter than the inverse repetition rate of the laser. The system lends itself for high-speed terahertz transmission measurements, e.g., to study wetting dynamics in real time.

  15. [Detection of Heart Rate of Fetal ECG Based on STFT and BSS].

    PubMed

    Wang, Xu; Cai, Kun

    2016-01-01

    Changes in heart rate of fetal is function regulating performance of the circulatory system and the central nervous system, it is significant to detect heart rate of fetus in perinatal fetal. This paper puts forward the fetal heart rate detection method based on short time Fourier transform and blind source separation. First of all, the mixed ECG signal was preprocessed, and then the wavelet transform technique was used to separate the fetal ECG signal with noise from mixed ECG signal, after that, the short-time Fourier transform and the blind separation were carried on it, and then calculated the correlation coefficient of it, Finally, An independent component that it has strongest correlation with the original signal was selected to make FECG peak detection and calculated the fetal instantaneous heart rate. The experimental results show that the method can improve the detection rate of the FECG peak (R), and it has high accuracy in fixing peak(R) location in the case of low signal-noise ratio. PMID:27197491

  16. Effect of 6-minute colonoscopy withdrawal time policy on polyp detection rate in a community hospital.

    PubMed

    Baker, Scott L; Miller, Roberta A; Creighton, Amy; Aguilar, Pedro S

    2015-01-01

    In 2002, a U.S. Multi-Society Task Force on colorectal cancer recommended a 6-minute or more withdrawal time as an indicator of a quality colonoscopy. In 2006, found a correlation between longer withdrawal time and an increased rate in the detection of adenomas. In January 2008, the endoscopy department at our institution adopted the Multi-Society Task Force recommendation. The aim of our study was to evaluate the effect of a minimal 6-minute withdrawal time policy at our institution on polyp detection rate. All colonoscopies performed for screening indications from April 2007 to September 2008 were reviewed retrospectively. Group I (pre-policy) was compared with Group II (post-policy). Data collected included age, gender, indication, polyp detection rate, size, and withdrawal time. Unpaired t tests evaluated pre- and postprocedure results. Fisher's exact tests were used to compare detection rates between withdrawal time less than 6 minutes and more than 6 minutes. Mann-Whitney U Tests were performed to analyze the significance between the number of polyps detected for withdrawal time less than 6 minutes versus more than 6 minutes. A total of 1,342 colonoscopies were available for analysis in Group I and 1,316 in Group II. Polyp detection rate was 46.6% in Group I versus 48.2% in Group II (p = .39), a non-statistically significant difference; however, there was a trend toward identifying small- and medium-sized polyps in Group II. Small polyps can carry a risk of severe dysplasia (). Data were then analyzed for withdrawal time. The polyp detection rate was 20.9 in procedures that took less than 6 minutes versus 48.3 in those that took more than 6 minutes (p ≤ .01). In this study, a 6-minute or more withdrawal time increased the polyp detection rate by 133% for all polyp sizes, especially small and medium. Small polyps (5 mm or less) should be removed and not ignored. A 6-minute or more withdrawal time should be mandatory in those patients without a previous colon

  17. Higher Adenoma Detection Rates with Endocuff-Assisted Colonoscopy – A Randomized Controlled Multicenter Trial

    PubMed Central

    Fitzlaff, Rüdiger; Röming, Hermann; Ameis, Detlev; Heinecke, Achim; Kunsch, Steffen; Ellenrieder, Volker; Ströbel, Philipp; Schepke, Michael; Meister, Tobias

    2014-01-01

    Objectives The Endocuff is a device mounted on the tip of the colonoscope to help flatten the colonic folds during withdrawal. This study aimed to compare the adenoma detection rates between Endocuff-assisted (EC) colonoscopy and standard colonoscopy (SC). Methods This randomized prospective multicenter trial was conducted at four academic endoscopy units in Germany. Participants: 500 patients (235 males, median age 64[IQR 54–73]) for colon adenoma detection purposes were included in the study. All patients were either allocated to EC or SC. The primary outcome measure was the determination of the adenoma detection rates (ADR). Results The ADR significantly increased with the use of the Endocuff compared to standard colonoscopy (35.4%[95% confidence interval{CI} 29–41%] vs. 20.7%[95%CI 15–26%], p<0.0001). Significantly more sessile polyps were detected by EC. Overall procedure time and withdrawal time did not differ. Caecal and ileum intubation rates were similar. No major adverse events occurred in both groups. In multivariate analysis, age (odds ratio [OR] 1.03; 95%[CI] 1.01–1.05), male sex (OR 1.74; 95%CI 1.10–2.73), withdrawal time (OR 1.16; 95%CI 1.05–1.30), procedure time (OR 1.07; 95%CI 1.04–1.10), colon cleanliness (OR 0.60; 95%CI 0.39–0.94) and use of Endocuff (OR 2.09; 95%CI 1.34–3.27) were independent predictors of adenoma detection rates. Conclusions EC increases the adenoma detection rate by 14.7%(95%CI 6.9–22.5%). EC is safe, effective, easy to handle and might reduce colorectal interval carcinomas. Trial Registration ClinicalTrials.gov NCT02034929. PMID:25470133

  18. SETI: The transmission rate of radio communication and the signal's detection

    NASA Astrophysics Data System (ADS)

    Fridman, P. A.

    2011-11-01

    The transmission rate of communication between radio telescopes on Earth and extraterrestrial intelligence (ETI) is here calculated up to distances of 1000 light years. Both phase-shift keying (PSK) and frequency-shift keying (FSK) modulation schemes are considered. It is shown that M-ary FSK is advantageous in terms of energy. Narrow-band pulses scattered over the spectrum sharing a common drift rate can be the probable signals of ETI. Modern SETI spectrum analyzers are well suited to searching for these types of signals. Such signals can be detected using the Hough transform which is a dedicated tool for detecting patterns in an image. The time-frequency plane representing the power output of the spectrum analyzer during the search for ETI gives an image from which the Hough transform (HT) can detect signal patterns with frequency drift.

  19. Extinction rate estimates for plant populations in revisitation studies: Importance of detectability

    USGS Publications Warehouse

    Kery, M.

    2004-01-01

    Many researchers have obtained extinction-rate estimates for plant populations by comparing historical and current records of occurrence. A population that is no longer found is assumed to have gone extinct. Extinction can then be related to characteristics of these populations, such as habitat type, size, or species, to test ideas about what factors may affect extinction. Such studies neglect the fact that a population may be overlooked, however, which may bias estimates of extinction rates upward. In addition, if populations are unequally detectable across groups to be compared, such as habitat type or population size, comparisons become distorted to an unknown degree. To illustrate the problem, I simulated two data sets, assuming a constant extinction rate, in which populations occurred in different habitats or habitats of different size and these factors affected their detectability The conventional analysis implicitly assumed that detectability equalled 1 and used logistic regression to estimate extinction rates. It wrongly identified habitat and population size as factors affecting extinction risk. In contrast, with capture-recapture methods, unbiased estimates of extinction rates were recovered. I argue that capture-recapture methods should be considered more often in estimations of demographic parameters in plant populations and communities.

  20. A visible light imaging device for cardiac rate detection with reduced effect of body movement

    NASA Astrophysics Data System (ADS)

    Jiang, Xiaotian; Liu, Ming; Zhao, Yuejin

    2014-09-01

    A visible light imaging system to detect human cardiac rate is proposed in this paper. A color camera and several LEDs, acting as lighting source, were used to avoid the interference of ambient light. From people's forehead, the cardiac rate could be acquired based on photoplethysmography (PPG) theory. The template matching method was used after the capture of video. The video signal was discomposed into three signal channels (RGB) and the region of interest was chosen to take the average gray value. The green channel signal could provide an excellent waveform of pulse wave on the account of green lights' absorptive characteristics of blood. Through the fast Fourier transform, the cardiac rate was exactly achieved. But the research goal was not just to achieve the cardiac rate accurately. With the template matching method, the effects of body movement are reduced to a large extent, therefore the pulse wave can be detected even while people are in the moving state and the waveform is largely optimized. Several experiments are conducted on volunteers, and the results are compared with the ones gained by a finger clamped pulse oximeter. The contrast results between these two ways are exactly agreeable. This method to detect the cardiac rate and the pulse wave largely reduces the effects of body movement and can probably be widely used in the future.

  1. Influence of growth rate and length on fluoride detection in human nails.

    PubMed

    Buzalaf, M A R; Pessan, J P; Alves, K M R P

    2006-01-01

    This study aimed to determine the lag time between increased fluoride (F) intake and F detection in human nails, as well as the influence of nails growth rate and length on this. Ten 20- to 35-year-old volunteers received 1.8 mg F daily, for 30 days. Nail growth rate and length were determined for all fingernails and toenails. Nail samples were collected at the beginning of the study and every 2 weeks (15 collections in all) and F concentrations were determined. The growth rate was statistically higher in fingernails than in toenails. No statistically significant differences were observed between right and left sides. Growth rate was significantly greater for big toenails than for the other toenails, but this pattern was not found for fingernails. The estimated mean lag times for F detection in fingernails and toenails were 101 and 123 days, respectively. An apparent increase in fingernail F concentrations was observed 84 days after the beginning of the study, although this was not statistically different from baseline. For toenails, statistically significant increases in F concentration in relation to baseline were observed 112 and 140 days after increased F ingestion. These increases occurred within the 95% confidence intervals for the calculated mean lag time for fluoride detection in nails. Considering the large amount of sample provided by the big toenails, together with their faster growth rate, as well as the fact that toenails are less prone to environmental contamination, our data suggest that big toenails are more suitable biomarkers of fluoride intake.

  2. Heart Rate Detection During Sleep Using a Flexible RF Resonator and Injection-Locked PLL Sensor.

    PubMed

    Kim, Sung Woo; Choi, Soo Beom; An, Yong-Jun; Kim, Byung-Hyun; Kim, Deok Won; Yook, Jong-Gwan

    2015-11-01

    Novel nonintrusive technologies for wrist pulse detection have been developed and proposed as systems for sleep monitoring using three types of radio frequency (RF) sensors. The three types of RF sensors for heart rate measurement on wrist are a flexible RF single resonator, array resonators, and an injection-locked PLL resonator sensor. To verify the performance of the new RF systems, we compared heart rates between presleep time and postsleep onset time. Heart rates of ten subjects were measured using the RF systems during sleep. All three RF devices detected heart rates at 0.2 to 1 mm distance from the skin of the wrist over clothes made of cotton fabric. The wrist pulse signals of a flexible RF single resonator were consistent with the signals obtained by a portable piezoelectric transducer as a reference. Then, we confirmed that the heart rate after sleep onset time significantly decreased compared to before sleep. In conclusion, the RF system can be utilized as a noncontact nonintrusive method for measuring heart rates during sleep.

  3. Cross Sections, relic abundance, and detection rates for neutralino dark matter

    SciTech Connect

    Griest, K.

    1988-06-01

    Neutralino annihilation and elastic scattering cross sections are derived which differ in important ways from previous work. These are applied to relic abundance calculations and to direct detection of neutralino dark matter from the galactic halo. Assuming the neutralino to be the lightest supersymmetric particle and that it is less massive than the Z sup 0, we find relic densities of neutralinos greater than 4 percent of critical density for almost all values of the supersymmetric parameters. We constrain the parameter space by using results from PETRA (chargino mass less than 23 GeV) and ASP, and then assuming a critical density of neutralinos, display event rates in a cryogenic detector for a variety of models. A new term implies spin independent elastic scattering even for those majorana particles and inclusion of propagator momenta increases detection rates by 10 to 300 percent for pure photinos. Z sup 0-squark interference leads to very low detection rates for some values of the parameters. The new term in the elastic cross section dominates for heavy, mostly spinless materials and mitigates the negative interference cancellations in light materials; except for the pure photino or pure higgsinos cases where it does not contribute. In general, the rates can be substantially different from the pure photino and pure higgsino special cases usually considered.

  4. Cross sections, relic abundance, and detection rates for neutralino dark matter

    SciTech Connect

    Griest, K.

    1988-10-15

    Neutralino annihilation and elastic scattering cross sections are derived which differ in important ways from previous work. These are applied to relic abundance calculations and to direct detection of neutralino dark matter from the galactic halo. Assuming the neutralino is the lightest supersymmetric particle and that it is less massive than the Z/sup 0/, we find relic densities of neutralinos greater than 4% of critical density for almost all values of the supersymmetric parameters. We constrain the parameter space by using results from the DESY e/sup +/e/sup -/ storage ring PETRA (chargino mass less than 23 GeV) and the ASP detector at the SLAC storage ring PEP, and then assuming a critical density of neutralinos, display event rates in a cryogenic detector for a variety of models. A new term implies ''spin-independent'' elastic scattering even for these Majorana particles and inclusion of propagator momenta increases detection rates by 10--300 % even for pure photinos. Z/sup 0/-squark interference leads to very low detection rates for some values of the parameters. The new term in the elastic cross section dominates for heavy, mostly spinless materials and mitigates the negative interference cancellations in light materials, except for the pure photino or pure Higgsino cases where it does not contribute. In general, the rates can be substantially different from the pure photino and pure Higgsino special cases usually considered.

  5. Cross Sections, relic abundance, and detection rates for neutralino dark matter

    NASA Technical Reports Server (NTRS)

    Griest, Kim

    1988-01-01

    Neutralino annihilation and elastic scattering cross sections are derived which differ in important ways from previous work. These are applied to relic abundance calculations and to direct detection of neutralino dark matter from the galactic halo. Assuming the neutralino to be the lightest supersymmetric particle and that it is less massive than the Z sup 0, we find relic densities of neutralinos greater than 4 percent of critical density for almost all values of the supersymmetric parameters. We constrain the parameter space by using results from PETRA (chargino mass less than 23 GeV) and ASP, and then assuming a critical density of neutralinos, display event rates in a cryogenic detector for a variety of models. A new term implies spin independent elastic scattering even for those majorana particles and inclusion of propagator momenta increases detection rates by 10 to 300 percent for pure photinos. Z sup 0-squark interference leads to very low detection rates for some values of the parameters. The new term in the elastic cross section dominates for heavy, mostly spinless materials and mitigates the negative interference cancellations in light materials; except for the pure photino or pure higgsinos cases where it does not contribute. In general, the rates can be substantially different from the pure photino and pure higgsino special cases usually considered.

  6. Simultaneous Source Detection and Analysis Using a Zero-inflated Count Rate Model.

    PubMed

    Klumpp, John; Brandl, Alexander

    2015-07-01

    This paper proposes a novel Bayesian technique that allows for simultaneous source detection and count rate analysis. The technique involves using priors, which include a finite probability that the source count rate is exactly zero. Such priors are called "zero-inflated." Solving the posterior distribution of a zero-inflated count rate model provides the probability that the sample contains a source and a probability distribution for the source count rate if the source exists, without the need to perform redundant computations. Sampling from zero-inflated distributions is straightforward and can be accomplished with easily accessible open source software. In addition, zero-inflated priors lead to finite posterior probabilities of "no source," which is an easy-to-understand and satisfying result. PMID:26011497

  7. Stochastic optimization for the detection of changes in maternal heart rate kinetics during pregnancy

    NASA Astrophysics Data System (ADS)

    Zakynthinaki, M. S.; Barakat, R. O.; Cordente Martínez, C. A.; Sampedro Molinuevo, J.

    2011-03-01

    The stochastic optimization method ALOPEX IV has been successfully applied to the problem of detecting possible changes in the maternal heart rate kinetics during pregnancy. For this reason, maternal heart rate data were recorded before, during and after gestation, during sessions of exercises of constant mild intensity; ALOPEX IV stochastic optimization was used to calculate the parameter values that optimally fit a dynamical systems model to the experimental data. The results not only demonstrate the effectiveness of ALOPEX IV stochastic optimization, but also have important implications in the area of exercise physiology, as they reveal important changes in the maternal cardiovascular dynamics, as a result of pregnancy.

  8. Reaction rate constant of HO2+O3 measured by detecting HO2 from photofragment fluorescence

    NASA Technical Reports Server (NTRS)

    Manzanares, E. R.; Suto, Masako; Lee, Long C.; Coffey, Dewitt, Jr.

    1986-01-01

    A room-temperature discharge-flow system investigation of the rate constant for the reaction 'HO2 + O3 yields OH + 2O2' has detected HO2 through the OH(A-X) fluorescence produced by photodissociative excitation of HO2 at 147 nm. A reaction rate constant of 1.9 + or - 0.3 x 10 to the -15th cu cm/molecule per sec is obtained from first-order decay of HO2 in excess O3; this agrees well with published data.

  9. Invariance of the bit error rate in the ancilla-assisted homodyne detection

    SciTech Connect

    Yoshida, Yuhsuke; Takeoka, Masahiro; Sasaki, Masahide

    2010-11-15

    We investigate the minimum achievable bit error rate of the discrimination of binary coherent states with the help of arbitrary ancillary states. We adopt homodyne measurement with a common phase of the local oscillator and classical feedforward control. After one ancillary state is measured, its outcome is referred to the preparation of the next ancillary state and the tuning of the next mixing with the signal. It is shown that the minimum bit error rate of the system is invariant under the following operations: feedforward control, deformations, and introduction of any ancillary state. We also discuss the possible generalization of the homodyne detection scheme.

  10. Automatic detection and quantification of sleep apnea using heart rate variability.

    PubMed

    Babaeizadeh, Saeed; White, David P; Pittman, Stephen D; Zhou, Sophia H

    2010-01-01

    Detection of sleep apnea using electrocardiographic (ECG) parameters is noninvasive and inexpensive. Our approach is based on the hypothesis that the patient's sleep-wake cycle during episodes of sleep apnea modulates heart rate (HR) oscillations. These HR oscillations appear as low-frequency fluctuations of instantaneous HR (IHR) and can be detected using HR variability analysis in the frequency domain. The purpose of this study was to evaluate the efficacy of our ECG-based algorithm for sleep apnea detection and quantification. The algorithm first detects normal QRS complexes and R-R intervals used to derive IHR and to estimate its spectral power in several frequency ranges. A quadratic classifier, trained on the learning set, uses 2 parameters to classify the 1-minute epoch in the middle of each 6-minute window as either apneic or normal. The windows are advanced by 1-minute steps, and the classification process is repeated. As a measure of quantification, the algorithm correctly classified 84.7% of all the 1-minute epochs in the evaluation database; and as a measure of the accuracy of apnea classification, the algorithm correctly classified all 30 test recordings in the evaluation database either as apneic or normal. Our sleep apnea detection algorithm based on analysis of a single-lead ECG provides accurate apnea detection and quantification. Because of its noninvasive and low-cost nature, this algorithm has the potential for numerous applications in sleep medicine.

  11. Detection of exudates in fundus imagery using a constant false-alarm rate (CFAR) detector

    NASA Astrophysics Data System (ADS)

    Khanna, Manish; Kapoor, Elina

    2014-05-01

    Diabetic retinopathy is the leading cause of blindness in adults in the United States. The presence of exudates in fundus imagery is the early sign of diabetic retinopathy so detection of these lesions is essential in preventing further ocular damage. In this paper we present a novel technique to automatically detect exudates in fundus imagery that is robust against spatial and temporal variations of background noise. The detection threshold is adjusted dynamically, based on the local noise statics around the pixel under test in order to maintain a pre-determined, constant false alarm rate (CFAR). The CFAR detector is often used to detect bright targets in radar imagery where the background clutter can vary considerably from scene to scene and with angle to the scene. Similarly, the CFAR detector addresses the challenge of detecting exudate lesions in RGB and multispectral fundus imagery where the background clutter often exhibits variations in brightness and texture. These variations present a challenge to common, global thresholding detection algorithms and other methods. Performance of the CFAR algorithm is tested against a publicly available, annotated, diabetic retinopathy database and preliminary testing suggests that performance of the CFAR detector proves to be superior to techniques such as Otsu thresholding.

  12. Predicting the capture rate in the Sun from a direct detection signal independently of the astrophysics

    NASA Astrophysics Data System (ADS)

    Herrero-Garcia, Juan

    2016-05-01

    The goal of the works on which this talk is based is to relate a direct detection signal with neutrino limits from the Sun independently of the astrophysics. In order to achieve this we derive a halo-independent lower bound on the dark matter capture rate in the Sun from a direct detection signal, with which one can set upper limits on the branching ratios into different channels from the absence of a high-energy neutrino flux in neutrino observatories. We also extend this bound to the case of inelastic scattering, both endothermic and exothermic. From two inelastic signals we show how the dark matter mass, the mass difference of the states and the couplings to neutrons and protons can be obtained. Furthermore, one can also pin down the exothermic/endothermic nature of the scattering, and therefore a precise lower bound on the solar capture rate is predicted. We also discuss isospin violation and uncertainties due to form factors.

  13. Swimmer detection and pose estimation for continuous stroke-rate determination

    NASA Astrophysics Data System (ADS)

    Zecha, Dan; Greif, Thomas; Lienhart, Rainer

    2012-02-01

    In this work we propose a novel approach to automatically detect a swimmer and estimate his/her pose continuously in order to derive an estimate of his/her stroke rate given that we observe the swimmer from the side. We divide a swimming cycle of each stroke into several intervals. Each interval represents a pose of the stroke. We use specifically trained object detectors to detect each pose of a stroke within a video and count the number of occurrences per time unit of the most distinctive poses (so-called key poses) of a stroke to continuously infer the stroke rate. We extensively evaluate the overall performance and the influence of the selected poses for all swimming styles on a data set consisting of a variety of swimmers.

  14. Luminance level of a monitor: influence on detectability and detection rate of breast cancer in 2D mammography

    NASA Astrophysics Data System (ADS)

    Bemelmans, Frédéric; Rashidnasab, Alaleh; Chesterman, Frédérique; Kimpe, Tom; Bosmans, Hilde

    2016-03-01

    Purpose: To evaluate lesion detectability and reading time as a function of luminance level of the monitor. Material and Methods: 3D mass models and microcalcification clusters were simulated into ROIs of for processing mammograms. Randomly selected ROIs were subdivided in three groups according to their background glandularity: high (>30%), medium (15-30%) and low (<15%). 6 non-spiculated masses (9 - 11mm), 6 spiculated masses (5 - 7mm) and 6 microcalcification clusters (2 - 4mm) were scaled in 3D to create a range of sizes. The linear attenuation coefficient (AC) of the masses was adjusted from 100% glandular tissue to 90%, 80%, 70%, to create different contrasts. Six physicists read the full database on Barco's Coronis Uniti monitor for four different luminance levels (300, 800, 1000 and 1200 Cd/m2), using a 4-AFC tool. Percentage correct (PC) and time were computed for all different conditions. A paired t-test was performed to evaluate the effect of luminance on PC and time. A multi-factorial analysis was performed using MANOVA.. Results: Paired t-test indicated a statistically significant difference for the average time per session between 300 and 1200; 800 and 1200; 1000 and 1200 Cd/m2, for all participants combined. There was no effect on PC. MANOVA denoted significantly lower reading times for high glandularity images at 1200 Cd/m2. Both types of masses were significantly faster detected at 1200 Cd/m2, for the contrast study. In the size study, microcalcification clusters and spiculated masses had a significantly higher detection rate at 1200 Cd/m2. Conclusion: These results demonstrate a significant decrease in reading time, while detectability remained constant.

  15. Improved bowel preparation increases polyp detection and unmasks significant polyp miss rate

    PubMed Central

    Papanikolaou, Ioannis S; Sioulas, Athanasios D; Magdalinos, Nektarios; Beintaris, Iosif; Lazaridis, Lazaros-Dimitrios; Polymeros, Dimitrios; Malli, Chrysoula; Dimitriadis, George D; Triantafyllou, Konstantinos

    2015-01-01

    AIM: To retrospectively compare previous-day vs split-dose preparation in terms of bowel cleanliness and polyp detection in patients referred for polypectomy. METHODS: Fifty patients underwent two colonoscopies: one diagnostic in a private clinic and a second for polypectomy in a University Hospital. The latter procedures were performed within 12 wk of the index ones. Examinations were accomplished by two experienced endoscopists, different in each facility. Twenty-seven patients underwent screening/surveillance colonoscopy, while the rest were symptomatic. Previous day bowel preparation was utilized initially and split-dose for polypectomy. Colon cleansing was evaluated using the Aronchick scale. We measured the number of detected polyps, and the polyp miss rates per-polyp. RESULTS: Excellent/good preparation was reported in 38 cases with previous-day preparation (76%) vs 46 with split-dose (92%), respectively (P = 0.03). One hundred and twenty-six polyps were detected initially and 169 subsequently (P < 0.0001); 88 vs 126 polyps were diminutive (P < 0.0001), 25 vs 29 small (P = 0.048) and 13 vs 14 equal or larger than 10 mm. The miss rates for total, diminutive, small and large polyps were 25.4%, 30.1%, 13.7% and 6.6%, respectively. Multivariate analysis revealed that split-dose preparation was significantly associated (OR, P) with increased number of polyps detected overall (0.869, P < 0.001), in the right (0.418, P = 0.008) and in the left colon (0.452, P = 0.02). CONCLUSION: Split-dose preparation improved colon cleansing, enhanced polyp detection and unmasked significant polyp miss rates. PMID:26488024

  16. Estimating the rate of retinal ganglion cell loss to detect glaucoma progression: An observational cohort study.

    PubMed

    Hirooka, Kazuyuki; Izumibata, Saeko; Ukegawa, Kaori; Nitta, Eri; Tsujikawa, Akitaka

    2016-07-01

    This study aimed to evaluate the relationship between glaucoma progression and estimates of the retinal ganglion cells (RGCs) obtained by combining structural and functional measurements in patients with glaucoma.In the present observational cohort study, we examined 116 eyes of 62 glaucoma patients. Using Cirrus optical coherence tomography (OCT), a minimum of 5 serial retinal nerve fiber layer (RNFL) measurements were performed in all eyes. There was a 3-year separation between the first and last measurements. Visual field (VF) testing was performed on the same day as the RNFL imaging using the Swedish Interactive Threshold Algorithm Standard 30-2 program of the Humphrey Field Analyzer. Estimates of the RGC counts were obtained from standard automated perimetry (SAP) and OCT, with a weighted average then used to determine a final estimate of the number of RGCs for each eye. Linear regression was used to calculate the rate of the RGC loss, and trend analysis was used to evaluate both serial RNFL thicknesses and VF progression.Use of the average RNFL thickness parameter of OCT led to detection of progression in 14 of 116 eyes examined, whereas the mean deviation slope detected progression in 31 eyes. When the rates of RGC loss were used, progression was detected in 41 of the 116 eyes, with a mean rate of RGC loss of -28,260 ± 8110 cells/year.Estimation of the rate of RGC loss by combining structural and functional measurements resulted in better detection of glaucoma progression compared to either OCT or SAP. PMID:27472691

  17. Microscopic Examination of Gallbladder Stones Improves Rate of Detection of Clonorchis sinensis Infection

    PubMed Central

    Ma, Rui-hong; Luo, Xiao-bing; Zheng, Pei-ming; Luo, Zhen-liang; Yang, Liu-qing

    2013-01-01

    To improve the rate of detection of Clonorchis sinensis infection, we compared different specimens from patients with cholecystolithiasis. Feces, gallbladder bile, and gallbladder stones collected from 179 consecutive patients with cholecystolithiasis underwent microscopic examination, and according to the results, 30 egg-positive and 30 egg-negative fecal, gallbladder bile, and gallbladder stone specimens, respectively, underwent real-time fluorescent PCR. The detection rates of eggs in feces, bile, and gallbladder stones were 30.7%, 44.7%, and 69.8%, respectively, and the differences were statistically significant (P < 0.01). The PCR results confirmed that the eggs in the specimens were C. sinensis eggs. Eggs in the feces were “fresh” and in the gallbladder stones were “old.” Microscopic examination of gallbladder stones may improve the detection rates of C. sinensis infection, which is important for developing individualized treatments to prevent the recurrence of gallbladder stones and to prevent the occurrence of severe liver damage and cholangiocarcinoma. PMID:23698535

  18. A burst-mode photon counting receiver with automatic channel estimation and bit rate detection

    NASA Astrophysics Data System (ADS)

    Rao, Hemonth G.; DeVoe, Catherine E.; Fletcher, Andrew S.; Gaschits, Igor D.; Hakimi, Farhad; Hamilton, Scott A.; Hardy, Nicholas D.; Ingwersen, John G.; Kaminsky, Richard D.; Moores, John D.; Scheinbart, Marvin S.; Yarnall, Timothy M.

    2016-04-01

    We demonstrate a multi-rate burst-mode photon-counting receiver for undersea communication at data rates up to 10.416 Mb/s over a 30-foot water channel. To the best of our knowledge, this is the first demonstration of burst-mode photon-counting communication. With added attenuation, the maximum link loss is 97.1 dB at λ=517 nm. In clear ocean water, this equates to link distances up to 148 meters. For λ=470 nm, the achievable link distance in clear ocean water is 450 meters. The receiver incorporates soft-decision forward error correction (FEC) based on a product code of an inner LDPC code and an outer BCH code. The FEC supports multiple code rates to achieve error-free performance. We have selected a burst-mode receiver architecture to provide robust performance with respect to unpredictable channel obstructions. The receiver is capable of on-the-fly data rate detection and adapts to changing levels of signal and background light. The receiver updates its phase alignment and channel estimates every 1.6 ms, allowing for rapid changes in water quality as well as motion between transmitter and receiver. We demonstrate on-the-fly rate detection, channel BER within 0.2 dB of theory across all data rates, and error-free performance within 1.82 dB of soft-decision capacity across all tested code rates. All signal processing is done in FPGAs and runs continuously in real time.

  19. Venous Invasion in Colorectal Cancer: Impact of Morphologic Findings on Detection Rate

    PubMed Central

    Hwang, Chungsu; Lee, Sojeong; Kim, Ahrong; Kim, Young-Geum; Ahn, Sang-Jeong; Park, Do Youn

    2016-01-01

    Purpose Venous invasion (VI) is widely accepted as a poor prognostic factor in colorectal cancer (CRC), and is indicated as a high-risk factor determining the use of adjuvant chemotherapy in CRC. However, there is marked interobserver and intraobserver variability in VI identification and marked variability in the real prevalence of VI in CRC. Materials and Methods We investigated the detection rate of VI in 93 consecutive cases of T3 or T4 CRC based on the following: original pathology report, review of hematoxylin and eosin (H&E) slides with attention to the “protruding tongue” and “orphan arteriole” signs, and elastic stain as the gold standard. Results Overall, the detection rate of VI was significantly increased as follows: 14/93 (15.1%) in the original pathology report, 38/93 (40.9%) in review of H&E slides with attention to the “protruding tongue” and “orphan arteriole” signs, and 45/93 (48.4%) using elastic stain. VI detection based on morphologic features showed 77.8% sensitivity and 91.1% specificity and showed a linear correlation (Spearman correlation coefficient, 0.727; p < 0.001) with VI detected by elastic stain. In addition, improved agreement between detection methods (detection on the basis of morphologic features, κ=0.719 vs. original pathology report, κ=0.318) was observed using kappa statistics. Conclusion Slide review with special attention to the “protruding tongue” and “orphan arteriole” signs could be used for better identification of VI in CRC in routine surgical practice. PMID:26875194

  20. Fuzzy entropy based motion artifact detection and pulse rate estimation for fingertip photoplethysmography.

    PubMed

    Paradkar, Neeraj; Chowdhury, Shubhajit Roy

    2014-01-01

    The paper presents a fingertip photoplethysmography (PPG) based technique to estimate the pulse rate of the subject. The PPG signal obtained from a pulse oximeter is used for the analysis. The input samples are corrupted with motion artifacts due to minor motion of the subjects. Entropy measure of the input samples is used to detect the motion artifacts and estimate the pulse rate. A three step methodology is adapted to identify and classify signal peaks as true systolic peaks or artifact. CapnoBase database and CSL Benchmark database are used to analyze the technique and pulse rate estimation was performed with positive predictive value and sensitivity figures of 99.84% and 99.32% respectively for CapnoBase and 98.83% and 98.84% for CSL database respectively.

  1. Detecting deception in children: an experimental study of the effect of event familiarity on CBCA ratings.

    PubMed

    Blandon-Gitlin, Iris; Pezdek, Kathy; Rogers, Martha; Brodie, Laura

    2005-04-01

    The CBCA is the most commonly used deception detection. technique worldwide. Pezdek et al. (2004) used a quasi-experimental design to assess children's accounts of a traumatic medical procedure; CBCA ratings were higher for descriptions of familiar than unfamiliar events. This study tested this effect using an experimental design and assessed the joint effect of familiarity and veracity on CBCA ratings. Children described a true or a fabricated event. Half described a familiar event; half described an unfamiliar event. Two CBCA-trained judges rated transcripts of the descriptions. CBCA scores were more strongly influenced by the familiarity than the actual veracity of the event, and CBCA scores were significantly correlated with age. CBCA results were compared with results from other measures. Together with the results of K. Pezdek et al. (2004) these findings suggest that in its current form, CBCA is of limited utility as a credibility assessment tool. PMID:15912723

  2. Satellite change detection analysis of deforestation rates and patterns along the Colombia-Ecuador border.

    PubMed

    Viña, Andrés; Echavarria, Fernando R; Rundquist, Donald C

    2004-05-01

    This study uses Landsat satellite data to document the rates and patterns of land-cover change along a portion of the Colombia-Ecuador border during a 23-yr period (1973-1996). Human colonization has resulted in extensive deforestation in both countries. Satellite change detection analysis showed that the annual rates of deforestation were considerably higher for the Colombian side of the border. In addition, loss of forest cover on the Colombian side for the study period was almost 43%, while only 22% on the Ecuadorian side. The study found that there is no single factor driving deforestation on either side of the border, but concluded that the higher rates on the Colombian side may be due to higher colonization pressures and intensification of illegal coca cultivation. On the Ecuador side of the border the satellite images documented patterns of deforestation that reflected road networks associated with oil exploration and development.

  3. Global parameter optimization for maximizing radioisotope detection probabilities at fixed false alarm rates

    NASA Astrophysics Data System (ADS)

    Portnoy, David; Feuerbach, Robert; Heimberg, Jennifer

    2011-10-01

    Today there is a tremendous amount of interest in systems that can detect radiological or nuclear threats. Many of these systems operate in extremely high throughput situations where delays caused by false alarms can have a significant negative impact. Thus, calculating the tradeoff between detection rates and false alarm rates is critical for their successful operation. Receiver operating characteristic (ROC) curves have long been used to depict this tradeoff. The methodology was first developed in the field of signal detection. In recent years it has been used increasingly in machine learning and data mining applications. It follows that this methodology could be applied to radiological/nuclear threat detection systems. However many of these systems do not fit into the classic principles of statistical detection theory because they tend to lack tractable likelihood functions and have many parameters, which, in general, do not have a one-to-one correspondence with the detection classes. This work proposes a strategy to overcome these problems by empirically finding parameter values that maximize the probability of detection for a selected number of probabilities of false alarm. To find these parameter values a statistical global optimization technique that seeks to estimate portions of a ROC curve is proposed. The optimization combines elements of simulated annealing with elements of genetic algorithms. Genetic algorithms were chosen because they can reduce the risk of getting stuck in local minima. However classic genetic algorithms operate on arrays of Booleans values or bit strings, so simulated annealing is employed to perform mutation in the genetic algorithm. The presented initial results were generated using an isotope identification algorithm developed at Johns Hopkins University Applied Physics Laboratory. The algorithm has 12 parameters: 4 real-valued and 8 Boolean. A simulated dataset was used for the optimization study; the "threat" set of spectra

  4. Detection of change points in underlying earthquake rates, with application to global mega-earthquakes

    NASA Astrophysics Data System (ADS)

    Touati, Sarah; Naylor, Mark; Main, Ian

    2016-02-01

    The recent spate of mega-earthquakes since 2004 has led to speculation of an underlying change in the global `background' rate of large events. At a regional scale, detecting changes in background rate is also an important practical problem for operational forecasting and risk calculation, for example due to volcanic processes, seismicity induced by fluid injection or withdrawal, or due to redistribution of Coulomb stress after natural large events. Here we examine the general problem of detecting changes in background rate in earthquake catalogues with and without correlated events, for the first time using the Bayes factor as a discriminant for models of varying complexity. First we use synthetic Poisson (purely random) and Epidemic-Type Aftershock Sequence (ETAS) models (which also allow for earthquake triggering) to test the effectiveness of many standard methods of addressing this question. These fall into two classes: those that evaluate the relative likelihood of different models, for example using Information Criteria or the Bayes Factor; and those that evaluate the probability of the observations (including extreme events or clusters of events) under a single null hypothesis, for example by applying the Kolmogorov-Smirnov and `runs' tests, and a variety of Z-score tests. The results demonstrate that the effectiveness among these tests varies widely. Information Criteria worked at least as well as the more computationally expensive Bayes factor method, and the Kolmogorov-Smirnov and runs tests proved to be the relatively ineffective in reliably detecting a change point. We then apply the methods tested to events at different thresholds above magnitude M ≥ 7 in the global earthquake catalogue since 1918, after first declustering the catalogue. This is most effectively done by removing likely correlated events using a much lower magnitude threshold (M ≥ 5), where triggering is much more obvious. We find no strong evidence that the background rate of large

  5. A SPITZER SURVEY OF MID-INFRARED MOLECULAR EMISSION FROM PROTOPLANETARY DISKS. I. DETECTION RATES

    SciTech Connect

    Pontoppidan, Klaus M.; Blake, Geoffrey A.; Meijerink, Rowin; Salyk, Colette; Carr, John S.; Najita, Joan

    2010-09-01

    We present a Spitzer InfraRed Spectrometer search for 10-36 {mu}m molecular emission from a large sample of protoplanetary disks, including lines from H{sub 2}O, OH, C{sub 2}H{sub 2}, HCN, and CO{sub 2}. This paper describes the sample and data processing and derives the detection rate of mid-infrared molecular emission as a function of stellar mass. The sample covers a range of spectral type from early M to A, and is supplemented by archival spectra of disks around A and B stars. It is drawn from a variety of nearby star-forming regions, including Ophiuchus, Lupus, and Chamaeleon. Spectra showing strong emission lines are used to identify which lines are the best tracers of various physical and chemical conditions within the disks. In total, we identify 22 T Tauri stars with strong mid-infrared H{sub 2}O emission. Integrated water line luminosities, where water vapor is detected, range from 5 x 10{sup -4} to 9 x 10{sup -3} L{sub sun}, likely making water the dominant line coolant of inner disk surfaces in classical T Tauri stars. None of the five transitional disks in the sample show detectable gaseous molecular emission with Spitzer upper limits at the 1% level in terms of line-to-continuum ratios (apart from H{sub 2}), but the sample is too small to conclude whether this is a general property of transitional disks. We find a strong dependence on detection rate with spectral type; no disks around our sample of 25 A and B stars were found to exhibit water emission, down to 1%-2% line-to-continuum ratios, in the mid-infrared, while more than half of disks around late-type stars (M-G) show sufficiently intense water emission to be detected by Spitzer, with a detection rate approaching 2/3 for disks around K stars. Some Herbig Ae/Be stars show tentative H{sub 2}O/OH emission features beyond 20 {mu}m at the 1%-2% level, however, and one of them shows CO{sub 2} in emission. We argue that the observed differences between T Tauri disks and Herbig Ae/Be disks are due to a

  6. Fluctuations in the Venusian Ionosphere and Their Effect on Venus Express Lightning Detection Rates

    NASA Astrophysics Data System (ADS)

    Hart, R. A.; Russell, C. T.; Zhang, T.

    2015-12-01

    Venus Express completed its nearly 9 year campaign at Earth's sister planet in late 2014. During this period the onboard fluxgate magnetometer collected data up to 64 Hz in frequency near periapsis. This is the expected frequency range for lightning-generated whistler-mode waves at Venus, between the local electron (~100 Hz) and ion gyrofrequencies (~1 Hz). These waves are right-hand circularly polarized and are guided by the local magnetic field. When the Venusian ionopause is low enough to reside in the collisional region, the interplanetary magnetic field can get carried down with the ions and magnetize the lower ionosphere. As the field travels towards terminator it gains a radial component, enabling whistlers to reach higher altitudes and be detected by the spacecraft. The mission covered almost an entire solar cycle and frequently observed a magnetized ionosphere during the solar minimum phase when the ionosphere was weak due to reduced incident EUV. In addition, the detection rate of whistler-mode signals varied with the solar cycle. Here, we examine the changes in the ionospheric properties associated with the evolution of the solar cycle and the rate of detection of these lightning-generated signals.

  7. The Influence of a Crosshair Visual Aid on Observer Detection of Simulated Fetal Heart Rate Signals.

    PubMed

    Kennedy, Rebecca A; Scerbo, Mark W; Anderson-Montoya, Brittany L; Belfore, Lee A; Abuhamad, Alfred Z; Davis, Stephen S

    2016-03-01

    Objective To determine whether a visual aid overlaid on fetal heart rate (FHR) tracings increases detection of critical signals relative to images with no visual aid. Study Design In an experimental study, 21 undergraduate students viewed 240 images of simulated FHR tracings twice, once with the visual aids and once without aids. Performance was examined for images containing three different types of FHR signals (early deceleration, late deceleration, and acceleration) and four different FHR signal-to-noise ratios corresponding to FHR variability types (absent, minimal, moderate, and marked) identified by the National Institute of Child Health and Human Development (2008). Performance was analyzed using repeated-measures analyses of variance. Results The presence of the visual aid significantly improved correct detections of signals overall and decreased false alarms for the marked variability condition. Conclusion The results of the study provide evidence that the presence of a visual aid was useful in helping novices identify FHR signals in simulated maternal-fetal heart rate images. Further, the visual aid was most useful for conditions in which the signal is most difficult to detect (when FHR variability is highest).

  8. The Influence of a Crosshair Visual Aid on Observer Detection of Simulated Fetal Heart Rate Signals.

    PubMed

    Kennedy, Rebecca A; Scerbo, Mark W; Anderson-Montoya, Brittany L; Belfore, Lee A; Abuhamad, Alfred Z; Davis, Stephen S

    2016-03-01

    Objective To determine whether a visual aid overlaid on fetal heart rate (FHR) tracings increases detection of critical signals relative to images with no visual aid. Study Design In an experimental study, 21 undergraduate students viewed 240 images of simulated FHR tracings twice, once with the visual aids and once without aids. Performance was examined for images containing three different types of FHR signals (early deceleration, late deceleration, and acceleration) and four different FHR signal-to-noise ratios corresponding to FHR variability types (absent, minimal, moderate, and marked) identified by the National Institute of Child Health and Human Development (2008). Performance was analyzed using repeated-measures analyses of variance. Results The presence of the visual aid significantly improved correct detections of signals overall and decreased false alarms for the marked variability condition. Conclusion The results of the study provide evidence that the presence of a visual aid was useful in helping novices identify FHR signals in simulated maternal-fetal heart rate images. Further, the visual aid was most useful for conditions in which the signal is most difficult to detect (when FHR variability is highest). PMID:26989564

  9. [Design of Oxygen Saturation, Heart Rate, Respiration Rate Detection System Based on Smartphone of Android Operating System].

    PubMed

    Zhu, Mingshan; Zeng, Bixin

    2015-03-01

    In this paper, we designed an oxygen saturation, heart rate, respiration rate monitoring system based on smartphone of android operating system, physiological signal acquired by MSP430 microcontroller and transmitted by Bluetooth module. PMID:26524782

  10. [Design of Oxygen Saturation, Heart Rate, Respiration Rate Detection System Based on Smartphone of Android Operating System].

    PubMed

    Zhu, Mingshan; Zeng, Bixin

    2015-03-01

    In this paper, we designed an oxygen saturation, heart rate, respiration rate monitoring system based on smartphone of android operating system, physiological signal acquired by MSP430 microcontroller and transmitted by Bluetooth module.

  11. Beat-to-beat heart rate detection in multi-lead abdominal fetal ECG recordings.

    PubMed

    Peters, C H L; van Laar, J O E H; Vullings, R; Oei, S G; Wijn, P F F

    2012-04-01

    Reliable monitoring of fetal condition often requires more information than is provided by cardiotocography, the standard technique for fetal monitoring. Abdominal recording of the fetal electrocardiogram may offer valuable additional information, but unfortunately is troubled by poor signal-to-noise ratios during certain parts of pregnancy. To increase the usability of abdominal fetal ECG recordings, an algorithm was developed that enhances fetal QRS complexes in these recordings and thereby provides a promising method for detecting the beat-to-beat fetal heart rate in recordings with poor signal-to-noise ratios. The method was evaluated on generated recordings with controlled signal-to-noise ratios and on actual recordings that were performed in clinical practice and were annotated by two independent experts. The evaluation on the generated signals demonstrated excellent results (sensitivity of 0.98 for SNR≥1.5). Only for SNR<2, the inaccuracy of the fetal heart rate detection exceeded 2 ms, which may still suffice for cardiotocography but is unacceptable for analysis of the beat-to-beat fetal heart rate variability. The sensitivity and positive predictive value of the method in actual recordings were reduced to approximately 90% for SNR≤2.4, but were excellent for higher signal-to-noise ratios.

  12. IMPROVED THEORETICAL PREDICTIONS OF MICROLENSING RATES FOR THE DETECTION OF PRIMORDIAL BLACK HOLE DARK MATTER

    SciTech Connect

    Cieplak, Agnieszka M.; Griest, Kim

    2013-04-20

    Primordial black holes (PBHs) remain a dark matter (DM) candidate of the Standard Model of Particle Physics. Previously, we proposed a new method of constraining the remaining PBH DM mass range using microlensing of stars monitored by NASA's Kepler mission. We improve this analysis using a more accurate treatment of the population of the Kepler source stars, their variability, and limb darkening. We extend the theoretically detectable PBH DM mass range down to 2 Multiplication-Sign 10{sup -10} M{sub Sun }, two orders of magnitude below current limits and one-third order of magnitude below our previous estimate. We address how to extract the DM properties, such as mass and spatial distribution, if PBH microlensing events were detected. We correct an error in a well-known finite-source limb-darkening microlensing formula and also examine the effects of varying the light curve cadence on PBH DM detectability. We also introduce an approximation for estimating the predicted rate of detection per star as a function of the star's properties, thus allowing for selection of source stars in future missions, and extend our analysis to planned surveys, such as the Wide-Field Infrared Survey Telescope.

  13. Wavelet based R-peak detection for heart rate variability studies.

    PubMed

    Sunkaria, R K; Saxena, S C; Kumar, V; Singhal, A M

    2010-02-01

    Detection of QRS complex in electrocardiogram (ECG) signals is of immense importance in cardiac health prognosis. In this paper a new symmetric wavelet for detection of R-peak is presented, which has been designed based on spectral characteristics and morphology of QRS complex. The detection of R-peak was carried out using this designed wavelet, and with existing symmetric wavelets such as db3, db6, haar and bior2.2. The detection accuracy with this wavelet is 99.99%, which is higher than those with existing symmetric wavelets. The algorithm has been tested on standard databases such as Fantasia database of normal and healthy subjects, MIT/BIH (Massachusetts Institute of Technology/Beth Israel Hospital) arrhythmia database, and on self-recorded electrocardiograms of normal subjects and patients under diseased stress. The study of heart rate variability (HRV) through computation of RR-tachogram using the new wavelet has proved to be effective in reliably evaluating HRV parameters. PMID:20059305

  14. Social Network Effects of Nonlifesaving Early-Stage Breast Cancer Detection on Mammography Rates

    PubMed Central

    Parker, Andrew M.

    2014-01-01

    Objectives. We estimated the effect of anecdotes of early-stage, screen-detected cancer for which screening was not lifesaving on the demand for mammography. Methods. We constructed an agent-based model of mammography decisions, in which 10 000 agents that represent women aged 40 to 100 years were linked together on a social network, which was parameterized with a survey of 716 women conducted through the RAND American Life Panel. Our model represents a population in equilibrium, with demographics reflecting the current US population based on the most recent available census data. Results. The aggregate effect of women learning about 1 category of cancers—those that would be detected but would not be lethal in the absence of screening—was a 13.8 percentage point increase in annual screening rates. Conclusions. Anecdotes of detection of early-stage cancers relayed through social networks may substantially increase demand for a screening test even when the detection through screening was nonlifesaving. PMID:25322304

  15. Detecting Parental Deception Using a Behavior Rating Scale during Assessment of Attention-Deficit/Hyperactivity Disorder: An Experimental Study

    ERIC Educational Resources Information Center

    Norfolk, Philip A.; Floyd, Randy G.

    2016-01-01

    It is often assumed that parents completing behavior rating scales during the assessment of attention-deficit/hyperactivity disorder (ADHD) can deliberately manipulate the outcomes of the assessment. To detect these actions, items designed to detect over-reporting or under-reporting of results are sometimes embedded in such rating scales. This…

  16. Vertex evoked potentials in a rating-scale detection task: Relation to signal probability

    NASA Technical Reports Server (NTRS)

    Squires, K. C.; Squires, N. K.; Hillyard, S. A.

    1974-01-01

    Vertex evoked potentials were recorded from human subjects performing in an auditory detection task with rating scale responses. Three values of a priori probability of signal presentation were tested. The amplitudes of the N1 and P3 components of the vertex potential associated with correct detections of the signal were found to be systematically related to the strictness of the response criterion and independent of variations in a priori signal probability. No similar evoked potential components were found associated with signal absent judgements (misses and correct rejections) regardless of the confidence level of the judgement or signal probability. These results strongly support the contention that the form of the vertex evoked response is closely correlated with the subject's psychophysical decision regarding the presence or absence of a threshold level signal.

  17. Energy Detection Based Estimation of Channel Occupancy Rate with Adaptive Noise Estimation

    NASA Astrophysics Data System (ADS)

    Lehtomäki, Janne J.; Vuohtoniemi, Risto; Umebayashi, Kenta; Mäkelä, Juha-Pekka

    Recently, there has been growing interest in opportunistically utilizing the 2.4GHz ISM-band. Numerous spectrum occupancy measurements covering the ISM-band have been performed to analyze the spectrum usage. However, in these campaigns the verification of the correctness of the obtained occupancy values for the highly dynamic ISM-band has not been presented. In this paper, we propose and verify channel occupancy rate (COR) estimation utilizing energy detection mechanism with a novel adaptive energy detection threshold setting method. The results are compared with the true reference COR values. Several different types of verification measurements showed that our setup can estimate the COR values of 802.11 traffic well, with negligible overestimation. The results from real-time real-life measurements also confirm that the proposed adaptive threshold setting method enables accurate thresholds even in the situations where multiple interferers are present in the received signal.

  18. Detection of arbitrarily large dynamic ground motions with a dense high-rate GPS network

    NASA Astrophysics Data System (ADS)

    Bock, Yehuda; Prawirodirdjo, Linette; Melbourne, Timothy I.

    2004-03-01

    We describe the detection of teleseismic surface waves from the 3 November 2002 Mw 7.9 Denali fault earthquake in Alaska with a dense network of 1 Hz GPS stations in southern California, about 3900 km from the event. Relative horizontal displacements with amplitudes in excess of 15 mm and duration of 700 seconds agree with integrated velocities recorded by nearby broadband seismometers with an rms difference of 2-3 mm. The displacements are derived from independent 1 Hz instantaneous positions demonstrating that a GPS network can provide direct measurements of arbitrarily large dynamic and static ground horizontal displacements at periods longer than 1 s and amplitudes above 2 mm, with an inherent precision (signal to noise) that improves indefinitely with amplitude without clipping and in real time. High-rate, real-time GPS networks can enhance earthquake detection and seismic risk mitigation and support other applications such as intelligent transportation and civil infrastructure monitoring.

  19. Automatic optimisation of gamma dose rate sensor networks: The DETECT Optimisation Tool

    NASA Astrophysics Data System (ADS)

    Helle, K. B.; Müller, T. O.; Astrup, P.; Dyve, J. E.

    2014-05-01

    Fast delivery of comprehensive information on the radiological situation is essential for decision-making in nuclear emergencies. Most national radiological agencies in Europe employ gamma dose rate sensor networks to monitor radioactive pollution of the atmosphere. Sensor locations were often chosen using regular grids or according to administrative constraints. Nowadays, however, the choice can be based on more realistic risk assessment, as it is possible to simulate potential radioactive plumes. To support sensor planning, we developed the DETECT Optimisation Tool (DOT) within the scope of the EU FP 7 project DETECT. It evaluates the gamma dose rates that a proposed set of sensors might measure in an emergency and uses this information to optimise the sensor locations. The gamma dose rates are taken from a comprehensive library of simulations of atmospheric radioactive plumes from 64 source locations. These simulations cover the whole European Union, so the DOT allows evaluation and optimisation of sensor networks for all EU countries, as well as evaluation of fencing sensors around possible sources. Users can choose from seven cost functions to evaluate the capability of a given monitoring network for early detection of radioactive plumes or for the creation of dose maps. The DOT is implemented as a stand-alone easy-to-use JAVA-based application with a graphical user interface and an R backend. Users can run evaluations and optimisations, and display, store and download the results. The DOT runs on a server and can be accessed via common web browsers; it can also be installed locally.

  20. Colonoscopic polyp detection rate is stable throughout the workday including evening colonoscopy sessions

    PubMed Central

    Thurtle, David; Pullinger, Michael; Tsigarides, Jordan; McIntosh, Iris; Steytler, Carla; Beales, Ian

    2014-01-01

    Objective: Polyp detection rate (PDR) is an accepted measure of colonoscopy quality. Several factors may influence PDR including time of procedure and order of colonoscopy within a session. Our unit provides evening colonoscopy lists (6-9 pm). We examined whether colonoscopy performance declines in the evening. Design: Data for all National Health Service (NHS) outpatient colonoscopies performed at Norfolk and Norwich University Hospital in 2011 were examined. Timing, demographics, indication and colonoscopy findings were recorded. Statistical analysis was performed using multivariate regression. Results: Data from 2576 colonoscopies were included: 1163 (45.1%) in the morning, 1123 (43.6%) in the afternoon and 290 (11.3%) in the evening.  Overall PDR was 40.80%. Males, increasing age and successful caecal intubation were all significantly associated with higher polyp detection. The indications ‘faecal occult blood screening’ (p<0.001) and ‘polyp surveillance’ (p<0.001) were strongly positively associated and ‘anaemia’ (p=0.01) was negatively associated with PDR. Following adjustment for  covariates, there was no significant difference in PDR between sessions. With the morning as the reference value, the odds ratio for polyp detection in the afternoon and evening were 0.93 (95% CI = 0.72-1.18) and 1.15 (95%CI = 0.82-1.61) respectively. PDR was not affected by rank of colonoscopy within a list, sedation dose or trainee-involvement. Conclusions: Time of day did not affect polyp detection rate in clinical practice. Evening colonoscopy had equivalent efficacy and is an effective tool in meeting increasing demands for endoscopy. Standardisation was shown to have a considerable effect as demographics, indication and endoscopist varied substantially between sessions. Evening sessions were popular with a younger population PMID:25132961

  1. Optimized filtering reduces the error rate in detecting genomic variants by short-read sequencing.

    PubMed

    Reumers, Joke; De Rijk, Peter; Zhao, Hui; Liekens, Anthony; Smeets, Dominiek; Cleary, John; Van Loo, Peter; Van Den Bossche, Maarten; Catthoor, Kirsten; Sabbe, Bernard; Despierre, Evelyn; Vergote, Ignace; Hilbush, Brian; Lambrechts, Diether; Del-Favero, Jurgen

    2012-01-01

    Distinguishing single-nucleotide variants (SNVs) from errors in whole-genome sequences remains challenging. Here we describe a set of filters, together with a freely accessible software tool, that selectively reduce error rates and thereby facilitate variant detection in data from two short-read sequencing technologies, Complete Genomics and Illumina. By sequencing the nearly identical genomes from monozygotic twins and considering shared SNVs as 'true variants' and discordant SNVs as 'errors', we optimized thresholds for 12 individual filters and assessed which of the 1,048 filter combinations were effective in terms of sensitivity and specificity. Cumulative application of all effective filters reduced the error rate by 290-fold, facilitating the identification of genetic differences between monozygotic twins. We also applied an adapted, less stringent set of filters to reliably identify somatic mutations in a highly rearranged tumor and to identify variants in the NA19240 HapMap genome relative to a reference set of SNVs. PMID:22178994

  2. Calculating inspector probability of detection using performance demonstration program pass rates

    NASA Astrophysics Data System (ADS)

    Cumblidge, Stephen; D'Agostino, Amy

    2016-02-01

    The United States Nuclear Regulatory Commission (NRC) staff has been working since the 1970's to ensure that nondestructive testing performed on nuclear power plants in the United States will provide reasonable assurance of structural integrity of the nuclear power plant components. One tool used by the NRC has been the development and implementation of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code Section XI Appendix VIII[1] (Appendix VIII) blind testing requirements for ultrasonic procedures, equipment, and personnel. Some concerns have been raised, over the years, by the relatively low pass rates for the Appendix VIII qualification testing. The NRC staff has applied statistical tools and simulations to determine the expected probability of detection (POD) for ultrasonic examinations under ideal conditions based on the pass rates for the Appendix VIII qualification tests for the ultrasonic testing personnel. This work was primarily performed to answer three questions. First, given a test design and pass rate, what is the expected overall POD for inspectors? Second, can we calculate the probability of detection for flaws of different sizes using this information? Finally, if a previously qualified inspector fails a requalification test, does this call their earlier inspections into question? The calculations have shown that one can expect good performance from inspectors who have passed appendix VIII testing in a laboratory-like environment, and the requalification pass rates show that the inspectors have maintained their skills between tests. While these calculations showed that the PODs for the ultrasonic inspections are very good under laboratory conditions, the field inspections are conducted in a very different environment. The NRC staff has initiated a project to systematically analyze the human factors differences between qualification testing and field examinations. This work will be used to evaluate and prioritize

  3. Comparison of cyclic correlation and the wavelet method for symbol rate detection

    NASA Astrophysics Data System (ADS)

    Carr, Richard; Whitney, James

    Software defined radio (SDR) is a relatively new technology that holds a great deal of promise in the communication field in general, and, in particular the area of space communications. Tra-ditional communication systems are comprised of a transmitter and a receiver, where through prior planning and scheduling, the transmitter and receiver are pre-configured for a particu-lar communication modality. For any particular modality the radio circuitry is configured to transmit, receive, and resolve one type of modulation at a certain data rate. Traditional radio's are limited by the fact that the circuitry is fixed. Software defined radios on the other hand do not suffer from this limitation. SDR's are comprised mainly of software modules which allow them to be flexible, in that they can resolve various types of modulation types that occur at different data rates. This ability is of very high importance in space where parameters of the communications link may need to be changed due to channel fading, reduced power, or other unforeseen events. In these cases the ability to autonomously change aspects of the radio's con-figuration becomes an absolute necessity in order to maintain communications. In order for the technology to work the receiver has to be able to determine the modulation type and the data rate of the signal. The data rate of the signal is one of the first parameters to be resolved, as it is needed to find the other signal parameters such as modulation type and the signal-to-noise ratio. There are a number of algorithms that have been developed to detect or estimate the data rate of a signal. This paper will investigate two of these algorithms, namely, the cyclic correlation algorithm and a wavelet-based detection algorithm. Both of these algorithms are feature-based algorithms, meaning that they make their estimations based on certain inherent features of the signals to which they are applied. The cyclic correlation algorithm takes advan-tage of the

  4. Blood Pressure and Heart Rate Variability to Detect Vascular Dysregulation in Glaucoma

    PubMed Central

    Koch, Eva Charlotte; Staab, Johanna; Fuest, Matthias; Witt, Katharina; Voss, Andreas; Plange, Niklas

    2015-01-01

    Purpose. To investigate blood pressure and heart rate variability in patients with primary open-angle glaucoma (POAG) to detect disturbed blood pressure regulation. Methods. Thirty-one patients with POAG (mean age 68 ± 10 years) and 48 control subjects (mean age 66 ± 10 years) were included in a prospective study. Continuous blood pressure and heart rate were simultaneously and noninvasively recorded over 30 min (Glaucoscreen, aviant GmbH, Jena, Germany). Data were analyzed calculating univariate linear (time domain and frequency domain), nonlinear (Symbolic Dynamics, SD) and bivariate (Joint Symbolic Dynamics, JSD) indices. Results. Using nonlinear methods, glaucoma patients were separated with more parameters compared to linear methods. In POAG, nonlinear univariate indices (pW113 and pW120_Sys) were increased while the indices pTH10_Sys and pTH11_Sys reflect a reduction of dominant patterns. Bivariate indices (JSDdia29, JSDdia50, and JSDdia52; coupling between heart rate and diastolic blood pressure) were increased in POAG. The optimum set consisting of six parameters (JSDdia29, JSDdia58, pTH9_Sys, pW231, pW110_Sys and pW120_Sys) revealed a sensitivity of 83.3% and specificity of 80.6%. Conclusions. Nonlinear uni- and bivariate indices of continuous recordings of blood pressure and heart rate are altered in glaucoma. Abnormal blood pressure variability suggests disturbed autonomic regulation in patients with glaucoma. PMID:26495136

  5. Estimating site occupancy rates for aquatic plants using spatial sub-sampling designs when detection probabilities are less than one

    USGS Publications Warehouse

    Nielson, Ryan M.; Gray, Brian R.; McDonald, Lyman L.; Heglund, Patricia J.

    2011-01-01

    Estimation of site occupancy rates when detection probabilities are <1 is well established in wildlife science. Data from multiple visits to a sample of sites are used to estimate detection probabilities and the proportion of sites occupied by focal species. In this article we describe how site occupancy methods can be applied to estimate occupancy rates of plants and other sessile organisms. We illustrate this approach and the pitfalls of ignoring incomplete detection using spatial data for 2 aquatic vascular plants collected under the Upper Mississippi River's Long Term Resource Monitoring Program (LTRMP). Site occupancy models considered include: a naïve model that ignores incomplete detection, a simple site occupancy model assuming a constant occupancy rate and a constant probability of detection across sites, several models that allow site occupancy rates and probabilities of detection to vary with habitat characteristics, and mixture models that allow for unexplained variation in detection probabilities. We used information theoretic methods to rank competing models and bootstrapping to evaluate the goodness-of-fit of the final models. Results of our analysis confirm that ignoring incomplete detection can result in biased estimates of occupancy rates. Estimates of site occupancy rates for 2 aquatic plant species were 19–36% higher compared to naive estimates that ignored probabilities of detection <1. Simulations indicate that final models have little bias when 50 or more sites are sampled, and little gains in precision could be expected for sample sizes >300. We recommend applying site occupancy methods for monitoring presence of aquatic species.

  6. DIURNAL AND ANNUAL VARIATIONS OF DIRECTIONAL DETECTION RATES OF DARK MATTER

    SciTech Connect

    Bandyopadhyay, Abhijit; Majumdar, Debasish E-mail: debasish.majumdar@saha.ac.in

    2012-02-10

    Direction-sensitive direct detection of weakly interacting massive particles (WIMPs) as dark matter would provide an unambiguous non-gravitational signature of dark matter. The diurnal variation of dark matter signal due to Earth's rotation around its own axis can be a significant signature for Galactic WIMPs. Because of a particular orientation of Earth's axis of rotation with respect to the WIMP wind direction, the apparent direction of WIMP wind as observed at a detector can alter widely in a day. In this work, we calculate the directional detection rates with their daily and yearly modulations in Earth-bound dark matter experiments considering detailed features of the geometry and dynamics of the Earth-Sun system along with the solar motion in a Galactic frame. A separate halo model, namely the dark disk model other than the usual standard halo model for dark matter halo, is also considered and the results for two models are compared. We demonstrate the results for two types of gas detectors, namely DRIFT (target material CS{sub 2}) and NEWAGE (target material CF{sub 4}), which use Time Projection Chamber techniques for measuring directionality of the recoil nucleus. The WIMP mass and recoil energy dependence of the daily variation of event rates are computed for a specific detector, and the sensitive ranges of mass and recoil energies for the considered detector are probed.

  7. Light WIMP Direct Detection Rates in Simulations of the Milky Way and Sagittarius Stream

    NASA Astrophysics Data System (ADS)

    Purcell, Chris W.

    2013-07-01

    I discuss the analysis of self-consistent N-body simulations of the Milky Way disk and the ongoing disruption of the Sagittarius dwarf satellite, toward the study of the effect of Sagittarius tidal debris on dark matter detection experiments. We find that the nearby Sagittarius debris is likely to have a non-negligible influence on dark matter detection experiments even when the stellar debris is centered several kpc from the solar neighborhood. Relative to models without an infalling Sagittarius dwarf, the Sagittarius dark matter debris in our models induces an energy-dependent enhancement of direct search event rates of as much as ~20 - 45%, an energy-dependent reduction in the amplitude of the annual modulation of the event rate by as much as a factor of two, a shift in the phase of the annual modulation by as much as ~20 days, and a shift in the recoil energy at which the modulation reverses phase. These influences of Sagittarius are of general interest in the interpretation of dark matter searches, but may be particularly important in the case of relatively light (m_X < 20 GeV) dark matter because the Sagittarius stream impacts the solar system at high speed compared to the primary halo dark matter.

  8. Dark matter direct detection rate in a generic model with micrOMEGAs_2.2

    NASA Astrophysics Data System (ADS)

    Bélanger, G.; Boudjema, F.; Pukhov, A.; Semenov, A.

    2009-05-01

    We present a new module of the micrOMEGAs package for the calculation of WIMP-nuclei elastic scattering cross sections relevant for the direct detection of dark matter through its interaction with nuclei in a large detector. With this new module, the computation of the direct detection rate is performed automatically for a generic model of new physics which contains a WIMP candidate. This model needs to be implemented within micrOMEGAs 2.2. Program summaryProgram title: micrOMEGAs2.2 Catalogue identifier: ADQR_v2_2 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADQR_v2_2.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 206 949 No. of bytes in distributed program, including test data, etc.: 2 245 230 Distribution format: tar.gz Programming language: C and Fortran Computer: PC, Alpha, Mac Operating system: UNIX (Linux, OSF1, Darwin, Cygwin) RAM: 17 MB depending on the number of processes required Classification: 1.9, 11.6 Catalogue identifier of previous version: ADQR_v2_1 Journal reference of previous version: Comput. Phys. Comm. 177 (2007) 894 Does the new version supersede the previous version?: Yes Nature of problem: Calculation of the relic density and of direct and indirect detection rates of the lightest stable particle in a generic new model of particle physics. Solution method: In numerically solving the evolution equation for the density of darkmatter, relativistic formulae for the thermal average are used. All tree-level processes for annihilation and coannihilation of new particles in the model are included. The cross-sections for all processes are calculated exactly with CalcHEP after definition of a model file. Higher-order QCD corrections to Higgs couplings to quark pairs are included. The coefficients of the effective Lagrangian which describes the

  9. Detection rates of geckos in visual surveys: Turning confounding variables into useful knowledge

    USGS Publications Warehouse

    Lardner, Bjorn; Rodda, Gordon H.; Yackel Adams, Amy A.; Savidge, Julie A.; Reed, Robert N.

    2016-01-01

    Transect surveys without some means of estimating detection probabilities generate population size indices prone to bias because survey conditions differ in time and space. Knowing what causes such bias can help guide the collection of relevant survey covariates, correct the survey data, anticipate situations where bias might be unacceptably large, and elucidate the ecology of target species. We used negative binomial regression to evaluate confounding variables for gecko (primarily Hemidactylus frenatus and Lepidodactylus lugubris) counts on 220-m-long transects surveyed at night, primarily for snakes, on 9,475 occasions. Searchers differed in gecko detection rates by up to a factor of six. The worst and best headlamps differed by a factor of at least two. Strong winds had a negative effect potentially as large as those of searchers or headlamps. More geckos were seen during wet weather conditions, but the effect size was small. Compared with a detection nadir during waxing gibbous (nearly full) moons above the horizon, we saw 28% more geckos during waning crescent moons below the horizon. A sine function suggested that we saw 24% more geckos at the end of the wet season than at the end of the dry season. Fluctuations on a longer timescale also were verified. Disturbingly, corrected data exhibited strong short-term fluctuations that covariates apparently failed to capture. Although some biases can be addressed with measured covariates, others will be difficult to eliminate as a significant source of error in longterm monitoring programs.

  10. Cardiac arrhythmia detection using combination of heart rate variability analyses and PUCK analysis.

    PubMed

    Mahananto, Faizal; Igasaki, Tomohiko; Murayama, Nobuki

    2013-01-01

    This paper presents cardiac arrhythmia detection using the combination of a heart rate variability (HRV) analysis and a "potential of unbalanced complex kinetics" (PUCK) analysis. Detection performance was improved by adding features extracted from the PUCK analysis. Initially, R-R interval data were extracted from the original electrocardiogram (ECG) recordings and were cut into small segments and marked as either normal or arrhythmia. HRV analyses then were conducted using the segmented R-R interval data, including a time-domain analysis, frequency-domain analysis, and nonlinear analysis. In addition to the HRV analysis, PUCK analysis, which has been implemented successfully in a foreign exchange market series to characterize change, was employed. A decision-tree algorithm was applied to all of the obtained features for classification. The proposed method was tested using the MIT-BIH arrhythmia database and had an overall classification accuracy of 91.73%. After combining features obtained from the PUCK analysis, the overall accuracy increased to 92.91%. Therefore, we suggest that the use of a PUCK analysis in conjunction with HRV analysis might improve performance accuracy for the detection of cardiac arrhythmia.

  11. Heart rate detection from single-foot plantar bioimpedance measurements in a weighing scale.

    PubMed

    Diaz, Delia H; Casas, Oscar; Pallas-Areny, Ramon

    2010-01-01

    Electronic bathroom scales are an easy-to-use, affordable mean to measure physiological parameters in addition to body weight. They have been proposed to obtain the ballistocardiogram (BCG) and derive from it the heart rate, cardiac output and systolic blood pressure. Therefore, weighing scales may suit intermittent monitoring in e-health and patient screening. Scales intended for bioelectrical impedance analysis (BIA) have also been proposed to estimate the heart rate by amplifying the pulsatile impedance component superimposed on the basal impedance. However, electronic weighing scales cannot easily obtain the BCG from people that have a single leg neither are bioimpedance measurements between both feet recommended for people wearing a pacemaker or other electronic implants, neither for pregnant women. We propose a method to detect the heart rate (HR) from bioimpedance measured in a single foot while standing on an bathroom weighting scale intended for BIA. The electrodes built in the weighing scale are used to apply a 50 kHz voltage between the outer electrode pair and to measure the drop in voltage across the inner electrode pair. The agreement with the HR simultaneously obtained from the ECG is excellent. We have also compared the drop in voltage across the waist and the thorax with that obtained when measuring bioimpedance between both feet to compare the possible risk of the proposed method to that of existing BIA scales.

  12. Detection of changes in the fractal scaling of heart rate and speed in a marathon race

    NASA Astrophysics Data System (ADS)

    Billat, Véronique L.; Mille-Hamard, Laurence; Meyer, Yves; Wesfreid, Eva

    2009-09-01

    The aim of this study was to detect changes in the fractal scaling behavior of heart rate and speed fluctuations when the average runner’s speed decreased with fatigue. Scaling analysis in heart rate (HR) and speed (S) dynamics of marathon runners was performed using the detrended fluctuation analysis (DFA) and the wavelet based structure function. We considered both: the short-range ( α1) and the long-range ( α2) scaling exponents for the DFA method separated by a change-point, n0=64=5.3 min (box length), the same for all the races. The variability of HR and S decreased in the second part of the marathon race, while the cardiac cost time series (i.e. the number of cardiac beats per meter) increased due to the decreasing speed behavior. The scaling exponents α1 and α2 of HR and α1 of S, increased during the race ( p<0.01) as did the HR wavelet scaling exponent ( τ). These findings provide evidence of the significant effect of fatigue induced by long exercise on the heart rate and speed variability.

  13. Adenoma detection rates decline with increasing procedural hours in an endoscopist’s workload

    PubMed Central

    Almadi, Majid A; Sewitch, Maida; Barkun, Alan N; Martel, Myriam; Joseph, Lawrence

    2015-01-01

    BACKGROUND: Operator fatigue may negatively influence adenoma detection (AD) during screening colonoscopy. OBJECTIVE: To better characterize factors affecting AD, including the number of hours worked, and the number and type of procedures performed before an index screening colonoscopy. METHODS: A retrospective cohort study was conducted involving individuals undergoing a screening colonoscopy at a major tertiary care hospital in Montreal, Quebec. Individuals were identified using an endoscopic reporting database; AD was identified by an electronic chart review. A hierarchical logistic regression analysis was performed to determine the association between patient- and endoscopist-related variables and AD. RESULTS: A total of 430 consecutive colonoscopies performed by 10 gastroenterologists and two surgeons were included. Patient mean (± SD) age was 63.4±10.9 years, 56.3% were males, 27.7% had undergone a previous colonoscopy and the cecal intubation rate was 95.7%. The overall AD rate was 25.7%. Age was associated with AD (OR 1.06 [95% CI 1.03 to 1.08]), while female sex (OR 0.44 [95% CI 0.25 to 0.75]), an indication for average-risk screening (OR 0.47 [95% CI 0.27 to 0.80]) and an increase in the number of hours during which endoscopies were performed before the index colonoscopy (OR 0.87 [95% CI 0.76 to 0.99]) were associated with lower AD rates. On exploratory univariable analysis, a threshold of 3 h of endoscopy time performed before the index colonoscopy was associated with decreased AD. CONCLUSION: The number of hours devoted to endoscopies before the index colonoscopy was inversely associated with AD rate, with decreased performance possibly as early as within 3 h. This metric should be confirmed in future studies and considered when optimizing scheduling practices. PMID:25996612

  14. Use of dew-point detection for quantitative measurement of sweating rate

    NASA Technical Reports Server (NTRS)

    Brengelmann, G. L.; Mckeag, M.; Rowell, L. B.

    1975-01-01

    A method of measuring sweat rate (SR) based on detection of dew point (DP) is proposed which has advantages that may be attractive to other laboratories concerned with recording SR from selected areas of skin. It is similar to other methods in that dry gas is passed through a capsule which isolates several square centimeters of skin surface. The difference is in the means of determining how much gaseous water is carried off in the effluent moist gas. The DP detector used is free of the drawbacks of previous devices. DP is obtained through the fundamental technique of determining the temperature at which condensate forms on a mirror. Variations in DP are tracked rapidly, and accurately (+ or - 0.8 C nominal, sensitivity + or - 0.05 C) over a wide range ( -40 C to +50 C) without measurable hysteresis. The detector asembly is rugged and readily opened for cleaning and inspection.

  15. Application of stochastic discrete event system framework for detection of induced low rate TCP attack.

    PubMed

    Barbhuiya, F A; Agarwal, Mayank; Purwar, Sanketh; Biswas, Santosh; Nandi, Sukumar

    2015-09-01

    TCP is the most widely accepted transport layer protocol. The major emphasis during the development of TCP was its functionality and efficiency. However, not much consideration was given on studying the possibility of attackers exploiting the protocol, which has lead to several attacks on TCP. This paper deals with the induced low rate TCP attack. Since the attack is relatively new, only a few schemes have been proposed to mitigate it. However, the main issues with these schemes are scalability, change in TCP header, lack of formal frameworks, etc. In this paper, we have adapted the stochastic DES framework for detecting the attack, which addresses most of these issues. We have successfully deployed and tested the proposed DES based IDS on a test bed.

  16. Detection of the oxygen consumption rate of migrating zebrafish by electrochemical equalization systems.

    PubMed

    Yasukawa, Tomoyuki; Koide, Masahiro; Tatarazako, Norihisa; Abe, Ryoko; Shiku, Hitoshi; Mizutani, Fumio; Matsue, Tomokazu

    2014-01-01

    A novel measurement system to determine oxygen consumption rates via respiration in migrating Zebrafish (Danio rerio) has been developed. A signal equalization system was adapted to detect oxygen in a chamber with one fish, because typical electrochemical techniques cannot measure respiration activities for migrating organisms. A closed chamber was fabricated using a pipet tip attached to a Pt electrode, and a columnar Vycor glass tip was used as the salt bridge. Pt electrode, which was attached to the chamber with one zebrafish, and Ag electrode were immersed in 10 mM potassium iodide (KI), and both the electrodes were connected externally to form a galvanic cell. Pt and Ag electrodes act as the cathode and anode to reduce oxygen and oxidize silver, respectively, allowing the deposition of insoluble silver iodide (AgI). The AgI acts as the signal source accumulated on the Ag electrode by conversion of oxygen. The amount of AgI deposited on the Ag electrode was determined by cathodic stripping voltammetry. The presence of zebrafish or its embryo led to a decrease in the stripping currents generated by a 10 min conversion of oxygen to AgI. The conversion of oxygen to AgI is disturbed by the migration of the zebrafish and allows the detection of different equalized signals corresponding to respiration activity. The oxygen consumption rates of the zebrafish and its embryo were estimated and determined to be ∼4.1 and 2.4 pmol·s(-1), respectively. The deposited AgI almost completely disappeared with a single stripping process. The signal equalization system provides a method to determine the respiration activities for migrating zebrafish and could be used to estimate environmental risk and for effective drug screening.

  17. Clinical Dementia Rating Scale Detects White Matter Changes in Older Adults at Risk for Alzheimer's Disease.

    PubMed

    Chang, Yu-Ling; Yen, Yu-Shiuan; Chen, Ta-Fu; Yan, Sui-Hing; Tseng, Wen-Yih Isaac

    2015-01-01

    This study investigated the putative changes in regional gray matter and cingulum bundle segments in mild cognitive impairment (MCI) by using two diagnostic criteria. Participants comprised 50 older adults with MCI and 22 healthy older controls (HC). The older adults with MCI were further divided into two groups defined by a global Clinical Dementia Rating (CDR) score of 0.5 and with (the CDR/NPT MCI group) or without (the CDR MCI group) objective cognitive impairments determined using neuropsychological tests (NPTs). Comparable regional gray matter integrity was observed among the three groups. However, the integrity of the right inferior segment of the cingulum bundle in the two MCI groups was more reduced than that in the HC group, and the CDR/NPT MCI group exhibited additional disruption in the left inferior cingulum bundle. The results also demonstrated that neuropsychological measures have greater predictive value for changes in white matter beyond the contribution of an informant-based instrument alone. Overall, the findings confirm the utility of informant-based assessment in detecting microstructural brain changes in high-risk older adults, even before objective cognitive impairment is evident. The findings also suggest that combining the neuropsychological measures with the informant-based assessment provided the greatest predictive value in assessing white matter disruption. The essential role of the white matter measurement as a biomarker for detecting individuals at a high risk of developing dementia was highlighted.

  18. Detecting recent selective sweeps while controlling for mutation rate and background selection.

    PubMed

    Huber, Christian D; DeGiorgio, Michael; Hellmann, Ines; Nielsen, Rasmus

    2016-01-01

    A composite likelihood ratio test implemented in the program sweepfinder is a commonly used method for scanning a genome for recent selective sweeps. sweepfinder uses information on the spatial pattern (along the chromosome) of the site frequency spectrum around the selected locus. To avoid confounding effects of background selection and variation in the mutation process along the genome, the method is typically applied only to sites that are variable within species. However, the power to detect and localize selective sweeps can be greatly improved if invariable sites are also included in the analysis. In the spirit of a Hudson-Kreitman-Aguadé test, we suggest adding fixed differences relative to an out-group to account for variation in mutation rate, thereby facilitating more robust and powerful analyses. We also develop a method for including background selection, modelled as a local reduction in the effective population size. Using simulations, we show that these advances lead to a gain in power while maintaining robustness to mutation rate variation. Furthermore, the new method also provides more precise localization of the causative mutation than methods using the spatial pattern of segregating sites alone. PMID:26290347

  19. Detection rate evaluation of ex-core detectors in the subcritical OPR-1000 reactor

    SciTech Connect

    Won, B. H.; Shin, C. H.; Kim, S. H.; Kim, H. C.; Park, J. J.; Kim, J. K.

    2012-07-01

    The OPR-1000 is a PWR reactor developed in Korea. One-type ex-core detectors for monitoring of power distributions were installed in the OPR-1000 reactor to alternate the three-types of the ex-core detectors. For the verification of the detection performances, neutron transport calculation was performed by using MCNP5 code. The reaction rate in the ex-core detectors and the neutron flux were evaluated by using MCNP5 code as changing the boron concentration from 1800 ppm to 1122 ppm in the subcritical condition. The reaction rate results in fission chamber show that minimum and maximum values are 0.03577 and 3.33563 reactions/cm{sup 3}-sec, respectively. This study can be directly used for the verification and improvement of fission chamber performance in using one-type ex-core detector. Also, it can be utilized for the production of the reference data in determining neutron source strength. It is expected the proposed simulation method can be utilized to the improvement of the dose monitoring system. (authors)

  20. Automatic detection of respiration rate from ambulatory single-lead ECG.

    PubMed

    Boyle, Justin; Bidargaddi, Niranjan; Sarela, Antti; Karunanithi, Mohan

    2009-11-01

    Ambulatory electrocardiography is increasingly being used in clinical practice to detect abnormal electrical behavior of the heart during ordinary daily activities. The utility of this monitoring can be improved by deriving respiration, which previously has been based on overnight apnea studies where patients are stationary, or the use of multilead ECG systems for stress testing. We compared six respiratory measures derived from a single-lead portable ECG monitor with simultaneously measured respiration air flow obtained from an ambulatory nasal cannula respiratory monitor. Ten controlled 1-h recordings were performed covering activities of daily living (lying, sitting, standing, walking, jogging, running, and stair climbing) and six overnight studies. The best method was an average of a 0.2-0.8 Hz bandpass filter and RR technique based on lengthening and shortening of the RR interval. Mean error rates with the reference gold standard were +/-4 breaths per minute (bpm) (all activities), +/-2 bpm (lying and sitting), and +/-1 breath per minute (overnight studies). Statistically similar results were obtained using heart rate information alone (RR technique) compared to the best technique derived from the full ECG waveform that simplifies data collection procedures. The study shows that respiration can be derived under dynamic activities from a single-lead ECG without significant differences from traditional methods. PMID:19775978

  1. Genomic Imbalances in Neonates With Birth Defects: High Detection Rates by Using Chromosomal Microarray Analysis

    PubMed Central

    Lu, Xin-Yan; Phung, Mai T.; Shaw, Chad A.; Pham, Kim; Neil, Sarah E.; Patel, Ankita; Sahoo, Trilochan; Bacino, Carlos A.; Stankiewicz, Pawel; Lee Kang, Sung-Hae; Lalani, Seema; Chinault, A. Craig; Lupski, James R.; Cheung, Sau W.; Beaudet, Arthur L.

    2009-01-01

    OBJECTIVES Our aim was to determine the frequency of genomic imbalances in neonates with birth defects by using targeted array-based comparative genomic hybridization, also known as chromosomal microarray analysis. METHODS Between March 2006 and September 2007, 638 neonates with various birth defects were referred for chromosomal microarray analysis. Three consecutive chromosomal microarray analysis versions were used: bacterial artificial chromosome-based versions V5 and V6 and bacterial artificial chromosome emulated oligonucleotide-based version V6 Oligo. Each version had targeted but increasingly extensive genomic coverage and interrogated >150 disease loci with enhanced coverage in genomic rearrangement-prone pericentromeric and subtelomeric regions. RESULTS Overall, 109 (17.1%) patients were identified with clinically significant abnormalities with detection rates of 13.7%, 16.6%, and 19.9% on V5, V6, and V6 Oligo, respectively. The majority of these abnormalities would not be defined by using karyotype analysis. The clinically significant detection rates by use of chromosomal microarray analysis for various clinical indications were 66.7% for “possible chromosomal abnormality” ± “others” (other clinical indications), 33.3% for ambiguous genitalia ± others, 27.1% for dysmorphic features + multiple congenital anomalies ± others, 24.6% for dysmorphic features ± others, 21.8% for congenital heart disease ± others, 17.9% for multiple congenital anomalies ± others, and 9.5% for the patients referred for others that were different from the groups defined. In all, 16 (2.5%) patients had chromosomal aneuploidies, and 81 (12.7%) patients had segmental aneusomies including common microdeletion or microduplication syndromes and other genomic disorders. Chromosomal mosaicism was found in 12 (1.9%) neonates. CONCLUSIONS Chromosomal microarray analysis is a valuable clinical diagnostic tool that allows precise and rapid identification of genomic imbalances

  2. Impact of the Introduction of Digital Mammography in an Organized Screening Program on the Recall and Detection Rate.

    PubMed

    Campari, Cinzia; Giorgi Rossi, Paolo; Mori, Carlo Alberto; Ravaioli, Sara; Nitrosi, Andrea; Vacondio, Rita; Mancuso, Pamela; Cattani, Antonella; Pattacini, Pierpaolo

    2016-04-01

    In 2012, the Reggio Emilia Breast Cancer Screening Program introduced digital mammography in all its facilities at the same time. The aim of this work is to analyze the impact of digital mammography introduction on the recall rate, detection rate, and positive predictive value. The program actively invites women aged 45-74 years. We included women screened in 2011, all of whom underwent film-screen mammography, and all women screened in 2012, all of whom underwent digital mammography. Double reading was used for all mammograms, with arbitration in the event of disagreement. A total of 42,240 women underwent screen-film mammography and 45,196 underwent digital mammography. The recall rate increased from 3.3 to 4.4% in the first year of digital mammography (relative recall adjusted by age and round 1.46, 95% CI = 1.37-1.56); the positivity rate for each individual reading, before arbitration, rose from 3 to 5.7%. The digital mammography recall rate decreased during 2012: after 12 months, it was similar to the recall rate with screen-film mammography. The detection rate was similar: 5.9/1000 and 5.2/1000 with screen-film and digital mammography, respectively (adjusted relative detection rate 0.95, 95% CI = 0.79-1.13). The relative detection rate for ductal carcinoma in situ remained the same. The introduction of digital mammography to our organized screening program had a negative impact on specificity, thereby increasing the recall rate. The effect was limited to the first 12 months after introduction and was attenuated by the double reading with arbitration. We did not observe any relevant effects on the detection rate.

  3. Detection Rate, Distribution, Clinical and Pathological Features of Colorectal Serrated Polyps

    PubMed Central

    Cao, Hai-Long; Chen, Xue; Du, Shao-Chun; Song, Wen-Jing; Wang, Wei-Qiang; Xu, Meng-Que; Wang, Si-Nan; Piao, Mei-Yu; Cao, Xiao-Cang; Wang, Bang-Mao

    2016-01-01

    Background: Colorectal serrated polyp is considered as histologically heterogeneous lesions with malignant potential in western countries. However, few Asian studies have investigated the comprehensive clinical features of serrated polyps in symptomatic populations. The aim of the study was to evaluate the features of colorectal serrated polyps in a Chinese symptomatic population. Methods: Data from all consecutive symptomatic patients were documented from a large colonoscopy database and were analyzed. Chi-square test or Fisher's exact test and logistic regression analysis were used for the data processing. Results: A total of 9191 (31.7%) patients were detected with at least one colorectal polyp. The prevalence of serrated polyps was 0.53% (153/28,981). The proportions of hyperplastic polyp (HP), sessile serrated adenoma/polyp (SSA/P), and traditional serrated adenoma (TSA) of all serrated polyps were 41.2%, 7.2%, and 51.6%, respectively, which showed a lower proportion of HP and SSA/P and a higher proportion of TSA. Serrated polyps appeared more in males and elder patients while there was no significant difference in the subtype distribution in gender and age. The proportions of large and proximal serrated polyps were 13.7% (21/153) and 46.4% (71/153), respectively. In total, 98.9% (89/90) serrated adenomas were found with dysplasia. Moreover, 14 patients with serrated polyps were found with synchronous advanced colorectal neoplasia, and large serrated polyps (LSPs) (odds ratio: 3.446, 95% confidence interval: 1.010–11.750, P < 0.05), especially large HPs, might have an association with synchronous advanced neoplasia (AN). Conclusions: The overall detection rate of colorectal serrated polyps in Chinese symptomatic patient population was low, and distribution pattern of three subtypes is different from previous reports. Moreover, LSPs, especially large HPs, might be associated with an increased risk of synchronous AN. PMID:27748334

  4. Optimizing convergence rates of alternating minimization reconstruction algorithms for real-time explosive detection applications

    NASA Astrophysics Data System (ADS)

    Bosch, Carl; Degirmenci, Soysal; Barlow, Jason; Mesika, Assaf; Politte, David G.; O'Sullivan, Joseph A.

    2016-05-01

    X-ray computed tomography reconstruction for medical, security and industrial applications has evolved through 40 years of experience with rotating gantry scanners using analytic reconstruction techniques such as filtered back projection (FBP). In parallel, research into statistical iterative reconstruction algorithms has evolved to apply to sparse view scanners in nuclear medicine, low data rate scanners in Positron Emission Tomography (PET) [5, 7, 10] and more recently to reduce exposure to ionizing radiation in conventional X-ray CT scanners. Multiple approaches to statistical iterative reconstruction have been developed based primarily on variations of expectation maximization (EM) algorithms. The primary benefit of EM algorithms is the guarantee of convergence that is maintained when iterative corrections are made within the limits of convergent algorithms. The primary disadvantage, however is that strict adherence to correction limits of convergent algorithms extends the number of iterations and ultimate timeline to complete a 3D volumetric reconstruction. Researchers have studied methods to accelerate convergence through more aggressive corrections [1], ordered subsets [1, 3, 4, 9] and spatially variant image updates. In this paper we describe the development of an AM reconstruction algorithm with accelerated convergence for use in a real-time explosive detection application for aviation security. By judiciously applying multiple acceleration techniques and advanced GPU processing architectures, we are able to perform 3D reconstruction of scanned passenger baggage at a rate of 75 slices per second. Analysis of the results on stream of commerce passenger bags demonstrates accelerated convergence by factors of 8 to 15, when comparing images from accelerated and strictly convergent algorithms.

  5. TEMPORAL TRENDS IN THE DETECTION RATES OF HEPATITIS B IN THE SANTA CATARINA STATE, BRAZIL

    PubMed Central

    Marcon, Chaiana Esmeraldino Mendes; Schneider, Ione Jayce Ceola; Traebert, Jefferson

    2014-01-01

    Hepatitis B is a serious public health problem. The state of Santa Catarina presents areas of high endemicity. The aim of this study was to describe temporal trends in detection rates of hepatitis B in the period from 2002 to 2009 in Santa Catarina and in its regions. A time series study was carried out. Crude rates were calculated and standardized by age using the direct method. Annual variation percentages were estimated by Joinpoint regression. There were two distinct and significant trends in Santa Catarina. From 2002 to 2006 a significant increase of 5.9% per year was observed. From 2006, there was a significant decrease of 6.4% per year. In this same period the southern and far-western regions had significant increases of 15.9% and 4.6% and significant decreases of 7.5% and 4.8%, respectively. Greater Florianópolis and Northeast also showed significant increases until 2006, of 15.4% and 17.4%, respectively. In the following period, non-significant decreases of 5.8% and 9.8% respectively were observed. Foz do Rio Itajaí and Planalto Serrano showed non-significant increases up to half of the studied period of 21.1% and 12.0%, respectively and after, significant decreases of 21.5% and 18.0%, respectively. Vale do Itajaí showed a significant decrease of 9.7%; Planalto Norte showed a non-significant decrease of 0.6% and Midwest a non-significant increase of 2.7% per year, in the period from 2002 to 2009. PMID:24626418

  6. Multiredshift Limits on the 21 cm Power Spectrum from PAPER

    NASA Astrophysics Data System (ADS)

    Jacobs, Daniel C.; Pober, Jonathan C.; Parsons, Aaron R.; Aguirre, James E.; Ali, Zaki S.; Bowman, Judd; Bradley, Richard F.; Carilli, Chris L.; DeBoer, David R.; Dexter, Matthew R.; Gugliucci, Nicole E.; Klima, Pat; Liu, Adrian; MacMahon, David H. E.; Manley, Jason R.; Moore, David F.; Stefan, Irina I.; Walbrugh, William P.

    2015-03-01

    The epoch of the reionization (EoR) power spectrum is expected to evolve strongly with redshift, and it is this variation with cosmic history that will allow us to begin to place constraints on the physics of reionization. The primary obstacle to the measurement of the EoR power spectrum is bright foreground emission. We present an analysis of observations from the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) telescope, which place new limits on the H i power spectrum over the redshift range of 7.5\\lt z\\lt 10.5, extending previously published single-redshift results to cover the full range accessible to the instrument. To suppress foregrounds, we use filtering techniques that take advantage of the large instrumental bandwidth to isolate and suppress foreground leakage into the interesting regions of k-space. Our 500 hr integration is the longest such yet recorded and demonstrates this method to a dynamic range of 104. Power spectra at different points across the redshift range reveal the variable efficacy of the foreground isolation. Noise-limited measurements of Δ2 at k = 0.2 hr Mpc-1 and z = 7.55 reach as low as (48 mK)2 (1σ). We demonstrate that the size of the error bars in our power spectrum measurement as generated by a bootstrap method is consistent with the fluctuations due to thermal noise. Relative to this thermal noise, most spectra exhibit an excess of power at a few sigma. The likely sources of this excess include residual foreground leakage, particularly at the highest redshift, unflagged radio frequency interference, and calibration errors. We conclude by discussing data reduction improvements that promise to remove much of this excess.

  7. Seeing better - Evidence based recommendations on optimizing colonoscopy adenoma detection rate

    PubMed Central

    Aranda-Hernández, Javier; Hwang, Jason; Kandel, Gabor

    2016-01-01

    Colorectal cancer is one of the three most frequent causes of cancer deaths in men and women in Europe and North America. Diagnosis and resection of adenomas has convincingly demonstrated its utility in diminishing colorectal cancer incidence. Therefore, colonoscopy is now the gold standard for colorectal cancer screening. But it is also known that colonoscopy effectiveness varies among endoscopists. Among different quality indicators, the most used is the adenoma detection rate (ADR) which is the percentage of average-risk patients for colorectal cancer who are found to have at least one adenoma or adenocarcinoma during a screening colonoscopy. There is compelling evidence supporting an inverse correlation between ADR and interval colorectal cancer (cancer found after a screening colonoscopy). Many factors such as quality of precolonoscopy preparation, additional observers, manoeuvres with the endoscope (second view, retroflexion, water inflation rather than air), time spent during withdrawal, changes in patient position, fold-flattener devices, new imaging or endoscopic modalities and use of intravenous or through the scope sprayed drugs, have been studied and developed with the aim of increasing the ADR. This reviews discusses these factors, and the current evidence, to “see better” in the colon and optimize ADR. PMID:26855536

  8. Using near infrared spectroscopy and heart rate variability to detect mental overload.

    PubMed

    Durantin, G; Gagnon, J-F; Tremblay, S; Dehais, F

    2014-02-01

    Mental workload is a key factor influencing the occurrence of human error, especially during piloting and remotely operated vehicle (ROV) operations, where safety depends on the ability of pilots to act appropriately. In particular, excessively high or low mental workload can lead operators to neglect critical information. The objective of the present study is to investigate the potential of functional near infrared spectroscopy (fNIRS) - a non-invasive method of measuring prefrontal cortex activity - in combination with measurements of heart rate variability (HRV), to predict mental workload during a simulated piloting task, with particular regard to task engagement and disengagement. Twelve volunteers performed a computer-based piloting task in which they were asked to follow a dynamic target with their aircraft, a task designed to replicate key cognitive demands associated with real life ROV operating tasks. In order to cover a wide range of mental workload levels, task difficulty was manipulated in terms of processing load and difficulty of control - two critical sources of workload associated with piloting and remotely operating a vehicle. Results show that both fNIRS and HRV are sensitive to different levels of mental workload; notably, lower prefrontal activation as well as a lower LF/HF ratio at the highest level of difficulty, suggest that these measures are suitable for mental overload detection. Moreover, these latter measurements point toward the existence of a quadratic model of mental workload. PMID:24184083

  9. National imagery interpretation rating system and the probabilities of detection, recognition, and identification

    NASA Astrophysics Data System (ADS)

    Driggers, Ronald G.; Cox, Paul G.; Kelley, Michael

    1997-07-01

    A large number of electro-optical (EO) and IR sensors are used on military platforms such as ground vehicles, low-altitude air vehicles, high-altitude air vehicles, and satellite systems. Ground vehicle and low-altitude air vehicle (rotary and fixed-wing aircraft) sensors typically use the probabilities of discrimination (detection, recognition, and identification) as design requirements and system performance indicators. High-altitude air vehicles and satellite sensors have traditionally used national imagery interpretation rating system (NIIRS) performance measures for guidance in design and measures of system performance. Data from the high-altitude air vehicle and satellite sensors are now being made available to the warfighter for many applications including surveillance and targeting. National imagery offices are being merged and restructured to support the warfighters and connectivities to high-altitude air vehicle sensors more effectively. It is becoming more apparent that the gap between the NIIRs approach and the probabilities of discrimination approach must be addressed. Users, engineers, and analysts must have a comparative basis for assessing the image quality between the two classes of sensors. The two approaches are described and compared.

  10. Subclinical Cardiotoxicity Detected by Strain Rate Imaging up to 14 months After Breast Radiation Therapy

    SciTech Connect

    Erven, Katrien; Florian, Anca; Slagmolen, Pieter; Sweldens, Caroline; Jurcut, Ruxandra; Wildiers, Hans; Voigt, Jens-Uwe; Weltens, Caroline

    2013-04-01

    Purpose: Strain rate imaging (SRI) is a new echocardiographic modality that enables accurate measurement of regional myocardial function. We investigated the role of SRI and troponin I (TnI) in the detection of subclinical radiation therapy (RT)-induced cardiotoxicity in breast cancer patients. Methods and Materials: This study prospectively included 75 women (51 left-sided and 24 right-sided) receiving adjuvant RT to the breast/chest wall and regional lymph nodes. Sequential echocardiographs with SRI were obtained before RT, immediately after RT, and 8 and 14 months after RT. TnI levels were measured on the first and last day of RT. Results: Mean heart and left ventricle (LV) doses were both 9 ± 4 Gy for the left-sided patients and 4 ± 4 Gy and 1 ± 0.4 Gy, respectively, for the right-sided patients. A decrease in strain was observed at all post-RT time points for left-sided patients (−17.5% ± 1.9% immediately after RT, −16.6% ± 1.4% at 8 months, and −17.7% ± 1.9% at 14 months vs −19.4% ± 2.4% before RT, P<.01) but not for right-sided patients. When we considered left-sided patients only, the highest mean dose was given to the anterior left ventricular (LV) wall (25 ± 14 Gy) and the lowest to the inferior LV wall (3 ± 3 Gy). Strain of the anterior wall was reduced after RT (−16.6% ± 2.3% immediately after RT, −16% ± 2.6% at 8 months, and −16.8% ± 3% at 14 months vs −19% ± 3.5% before RT, P<.05), whereas strain of the inferior wall showed no significant change. No changes were observed with conventional echocardiography. Furthermore, mean TnI levels for the left-sided patients were significantly elevated after RT compared with before RT, whereas TnI levels of the right-sided patients remained unaffected. Conclusions: In contrast to conventional echocardiography, SRI detected a regional, subclinical decline in cardiac function up to 14 months after breast RT. It remains to be determined whether these changes are related to clinical

  11. Good is better than excellent: Bowel preparation quality and adenoma detection rates

    PubMed Central

    Calderwood, Audrey H.; Thompson, Katherine; Schroy, Paul C.; Lieberman, David A.; Jacobson, Brian C.

    2015-01-01

    Background Inadequate bowel cleanliness is associated with missed lesions, yet whether polyp and adenoma detection rates (PDR, ADR) increase at the highest levels of bowel cleanliness is unknown. Objective To evaluate the association between bowel preparation quality using the Boston Bowel Preparation Scale (BBPS) and PDR and ADR among colonoscopies with adequate preparation. Design Cross-sectional analysis Setting Boston Medical Center (BMC) and the Clinical Outcomes Research Initiative (CORI) Patients Average-risk ambulatory patients attending screening colonoscopy with adequate bowel preparation defined as BBPS score ≥ 6 Main Outcome Measurements PDR and ADR stratified by BBPS score Results Among the 3713 colonoscopies at BMC performed by 19 endoscopists, the PDR, ADR, and advanced ADR were 49.8%, 37.7%, and 6.0%, respectively. Among the 5532 colonoscopies in CORI performed by 85 endoscopists at 41 different sites, the PDR was 44.5% and PDR for polyps >9 mm (surrogate for advanced ADR) was 6.2%. The PDR associated with total BBPS scores of 6, 7, and 8 were higher than those associated with a BBPS score of 9 at BMC (BBPS 6:51%, BBPS 7:53%, BBPS 8:52% vs. BBBPS 9:46%; P =.002) and CORI (BBPS 6:51%, BBPS 7:48%, BBPS 8:45% vs. BBPS 9:40%; P <.0001). This trend persisted after adjusting for age, gender, race/ethnicity and was also observed for ADR and advanced ADR. PDR was higher among “good” compared to “excellent” preparations at BMC (OR 1.3 [1.0-1.5]) and CORI (OR 4.7 [3.1-7.1]). Limitations Retrospective study Conclusions The PDR and ADR decreased at the highest levels of bowel cleanliness. Endoscopists finding a pristine bowel preparation should avoid a sense of over-confidence for polyp detection during the inspection phase of screening colonoscopy and still perform a careful evaluation for polyps. Furthermore, endoscopists expending additional effort to maximize cleansing of the bowel should never sacrifice on their inspection technique or inspection

  12. A novel method to detect proteins evolving at correlated rates: identifying new functional relationships between coevolving proteins.

    PubMed

    Clark, Nathaniel L; Aquadro, Charles F

    2010-05-01

    Interacting proteins evolve at correlated rates, possibly as the result of evolutionary pressures shared by functional groups and/or coevolution between interacting proteins. This evolutionary signature can be exploited to learn more about protein networks and to infer functional relationships between proteins on a genome-wide scale. Multiple methods have been introduced that detect correlated evolution using amino acid distances. One assumption made by these methods is that the neutral rate of nucleotide substitution is uniform over time; however, this is unlikely and such rate heterogeneity would adversely affect amino acid distance methods. We explored alternative methods that detect correlated rates using protein-coding nucleotide sequences in order to better estimate the rate of nonsynonymous substitution at each branch (d(N)) normalized by the underlying synonymous substitution rate (d(S)). Our novel likelihood method, which was robust to realistic simulation parameters, was tested on Drosophila nuclear pore proteins, which form a complex with well-documented physical interactions. The method revealed significantly correlated evolution between nuclear pore proteins, where members of a stable subcomplex showed stronger correlations compared with those proteins that interact transiently. Furthermore, our likelihood approach was better able to detect correlated evolution among closely related species than previous methods. Hence, these sequence-based methods are a complementary approach for detecting correlated evolution and could be applied genome-wide to provide candidate protein-protein interactions and functional group assignments using just coding sequences.

  13. Evaluation of the beat-to-beat detection accuracy of PulseOn wearable optical heart rate monitor.

    PubMed

    Parak, Jakub; Tarniceriu, Adrian; Renevey, Philippe; Bertschi, Mattia; Delgado-Gonzalo, Ricard; Korhonen, Ilkka

    2015-08-01

    Heart rate variability (HRV) provides significant information about the health status of an individual. Optical heart rate monitoring is a comfortable alternative to ECG based heart rate monitoring. However, most available optical heart rate monitoring devices do not supply beat-to-beat detection accuracy required by proper HRV analysis. We evaluate the beat-to-beat detection accuracy of a recent wrist-worn optical heart rate monitoring device, PulseOn (PO). Ten subjects (8 male and 2 female; 35.9±10.3 years old) participated in the study. HRV was recorded with PO and Firstbeat Bodyguard 2 (BG2) device, which was used as an ECG based reference. HRV was recorded during sleep. As compared to BG2, PO detected on average 99.57% of the heartbeats (0.43% of beats missed) and had 0.72% extra beat detection rate, with 5.94 ms mean absolute error (MAE) in beat-to-beat intervals (RRI) as compared to the ECG based RRI BG2. Mean RMSSD difference between PO and BG2 derived HRV was 3.1 ms. Therefore, PO provides an accurate method for long term HRV monitoring during sleep.

  14. Detecting trends in raptor counts: power and type I error rates of various statistical tests

    USGS Publications Warehouse

    Hatfield, J.S.; Gould, W.R.; Hoover, B.A.; Fuller, M.R.; Lindquist, E.L.

    1996-01-01

    We conducted simulations that estimated power and type I error rates of statistical tests for detecting trends in raptor population count data collected from a single monitoring site. Results of the simulations were used to help analyze count data of bald eagles (Haliaeetus leucocephalus) from 7 national forests in Michigan, Minnesota, and Wisconsin during 1980-1989. Seven statistical tests were evaluated, including simple linear regression on the log scale and linear regression with a permutation test. Using 1,000 replications each, we simulated n = 10 and n = 50 years of count data and trends ranging from -5 to 5% change/year. We evaluated the tests at 3 critical levels (alpha = 0.01, 0.05, and 0.10) for both upper- and lower-tailed tests. Exponential count data were simulated by adding sampling error with a coefficient of variation of 40% from either a log-normal or autocorrelated log-normal distribution. Not surprisingly, tests performed with 50 years of data were much more powerful than tests with 10 years of data. Positive autocorrelation inflated alpha-levels upward from their nominal levels, making the tests less conservative and more likely to reject the null hypothesis of no trend. Of the tests studied, Cox and Stuart's test and Pollard's test clearly had lower power than the others. Surprisingly, the linear regression t-test, Collins' linear regression permutation test, and the nonparametric Lehmann's and Mann's tests all had similar power in our simulations. Analyses of the count data suggested that bald eagles had increasing trends on at least 2 of the 7 national forests during 1980-1989.

  15. [Evaluation of heart impact in the 100 m extreme intensity sport using near-infrared non-invasive muscle oxygen detecting device and sports heart rate detection technology].

    PubMed

    Wang, Pei-Yong; Long, Fei-Xiao; Fu, Lan-Ying; Li, Yue; Ding, Hai-Shu; Qu, An-Lian; Zhou, Xiao-Ping

    2010-02-01

    Using continuous two wavelength near-infrared technology to detect the variation in the consistency of oxygen hemoglobin in the muscle and the sports heart rate wireless real time collection technology, we devised the real time muscle tissue oxygenation and instantaneous heart rate experiment scheme and implemented it for the process of the 100 m run with two parameters given simultaneously. The experiment shows that the concentration of the oxygen hemoglobin in the muscle tissue continues decreasing after the end of the 100 m run, and the time interval between the moment when the concentration of the oxygen hemoglobin attains the minimum value and the moment when the athletes finish the 100 m run is (6.65 +/- 1.10) sec; while the heart rate continues increasing after the end of the 100 m run, and the time interval between the moment when the heart rate attains the maximum value and the moment when the athletes finish the 100 m run is (8.00 +/- 1.57) sec. The results show that the two wavelength near-infrared tissue oxygenation detection technology and the sports heart rate real time collection equipment can accurately measure the sports tissue oxygenation and the heart rate in the extreme intensity sport, and reveal the process of muscle oxygen transportation and consumption and its dynamic character with the heart rate in the extreme intensity sport.

  16. Implementation of a program to improve the quality of colonoscopy increases the neoplasia detection rate: a prospective study

    PubMed Central

    Viola, Luis Alberto; Cassella, Federico; Wonaga, Andrés; Arnao Dellamea, Gloria; Di Paola, Leandro; Ubeira Salim, Rodrigo; Fernández, José Luis

    2016-01-01

    Background and study aims: Endoscopists worldwide have been encouraged to report quality indicators in order to evaluate their performance. We aimed to determine whether a program to improve the quality of colonoscopy results in better rates of neoplasia detection. Patients and methods: This is a prospective study set in a private endoscopy center. From May 2009 to March 2010, we evaluated 1573 consecutive colonoscopies (group 1). After the implementation of a quality program, from February 2011 to January 2012, we prospectively evaluated 1583 colonoscopies (group 2). Our quality-enhancing intervention consisted of instructing both patients and endoscopists. We measured the cecal intubation rate and the neoplasia detection rate. Overall neoplasias, high-risk adenomas, carcinomas, right colon adenomas, and adenomas detected in screening studies were analyzed. Results: Cecal intubation was documented in 1384 cases from group 1 (88 %) and 1534 from group 2 (96.9 %) (P < 0.0001). The neoplasia detection rates in groups 1 and 2 were, respectively: neoplasias 288 (18.3 %) and 427 (27 %) (P < 0.0001), high-risk adenomas 76 (4.8 %) and 142 (9 %) (P < 0.0001), carcinomas 16 (1 %) and 21 (1.3 %) (P = 0.52), right colon adenomas 112 (7.1 %) and 154 (9.7 %) (P = 0.01), and adenomas 141 (16.5 %) and 233 (28 %) (P < 0.0001). Conclusions: Implementation of a quality program improves the neoplasia detection rate. Because of the small number of cancerous lesions found in both groups, we were unable to identify differences in the carcinoma detection rate. PMID:26793787

  17. Estimating detection rates of compact binary inspirals with networks of ground-based gravitational-wave detectors

    NASA Astrophysics Data System (ADS)

    Seto, Naoki

    2014-07-01

    In a recent paper, Schutz proposed an analytical approximation for simplifying the treatment of the polarization angle and conveniently evaluating relative detection rates of compact binary inspirals for various networks of ground-based interferometers. We derive relative event rates by strictly handling the polarization angle, and we quantitatively examine the validity of Schutz's approximation. The associated error of the approximation is rigorously shown to be less than 1.02%, irrespective of the details of the detector networks.

  18. Transfer Rate Edited experiment for the selective detection of Chemical Exchange via Saturation Transfer (TRE-CEST)

    NASA Astrophysics Data System (ADS)

    Friedman, Joshua I.; Xia, Ding; Regatte, Ravinder R.; Jerschow, Alexej

    2015-07-01

    Chemical Exchange Saturation Transfer (CEST) magnetic resonance experiments have become valuable tools in magnetic resonance for the detection of low concentration solutes with far greater sensitivity than direct detection methods. Accurate measures of rates of chemical exchange provided by CEST are of particular interest to biomedical imaging communities where variations in chemical exchange can be related to subtle variations in biomarker concentration, temperature and pH within tissues using MRI. Despite their name, however, traditional CEST methods are not truly selective for chemical exchange and instead detect all forms of magnetization transfer including through-space NOE. This ambiguity crowds CEST spectra and greatly complicates subsequent data analysis. We have developed a Transfer Rate Edited CEST experiment (TRE-CEST) that uses two different types of solute labeling in order to selectively amplify signals of rapidly exchanging proton species while simultaneously suppressing 'slower' NOE-dominated magnetization transfer processes. This approach is demonstrated in the context of both NMR and MRI, where it is used to detect the labile amide protons of proteins undergoing chemical exchange (at rates ⩾ 30 s-1) while simultaneously eliminating signals originating from slower (∼5 s-1) NOE-mediated magnetization transfer processes. TRE-CEST greatly expands the utility of CEST experiments in complex systems, and in-vivo, in particular, where it is expected to improve the quantification of chemical exchange and magnetization transfer rates while enabling new forms of imaging contrast.

  19. Comparison of detection rates of breeding marsh birds in passive and playback surveys at Lacreek National Wildlife Refuge, South Dakota

    USGS Publications Warehouse

    Allen, T.; Finkbeiner, S.L.; Johnson, D.H.

    2004-01-01

    We compared detection rates of passive and playback breeding bird survey techniques on elusive marsh birds - Pied-billed Grebe (Podilymbus podiceps), American Bittern (Botaurus lentiginosus), Least Bittern (Ixobrychus exilis), Virginia Rail (Rallus limicola), and Sora (Porzana carolina) - during a two-year study at Lacreek National Wildlife Refuge, in southwestern South Dakota. We conducted 151 passive point counts followed by playback-response surveys at the same points in marsh-bird habitat on the refuge. Playback surveys detected secretive water birds more frequently than our passive surveys, increasing rates for each species by factors of 2.4 to 7.0. The distance a bird was detected from a point varied with the species and the survey technique.

  20. Prostate-specific Antigen Density Variation Rate as a Potential Guideline Parameter for Second Prostate Cancer Detection Biopsy

    PubMed Central

    Xie, Gan-Sheng; Lyv, Jin-Xing; Li, Gang; Yan, Chun-Yin; Hou, Jian-Quan; Pu, Jin-Xian; Ding, Xiang; Huang, Yu-Hua

    2016-01-01

    Background: The diagnostic value of current prostate-specific antigen (PSA) tests is challenged by the poor detection rate of prostate cancer (PCa) in repeat prostate biopsy. In this study, we proposed a novel PSA-related parameter named PSA density variation rate (PSADVR) and designed a clinical trial to evaluate its potential diagnostic value for detecting PCa on a second prostate biopsy. Methods: Data from 184 males who underwent second ultrasound-guided prostate biopsy 6 months after the first biopsy were included in the study. The subjects were divided into PCa and non-PCa groups according to the second biopsy pathological results. Prostate volume, PSA density (PSAD), free-total PSA ratio, and PSADVR were calculated according to corresponding formulas at the second biopsy. These parameters were compared using t-test or Mann-Whitney U-test between PCa and non-PCa groups, and receiver operating characteristic analysis were used to evaluate their predictability on PCa detection. Results: PCa was detected in 24 patients on the second biopsy. Mean values of PSA, PSAD, and PSADVR were greater in the PCa group than in the non-PCa group (8.39 μg/L vs. 7.16 μg/L, 0.20 vs. 0.16, 14.15% vs. −1.36%, respectively). PSADVR had the largest area under the curve, with 0.667 sensitivity and 0.824 specificity when the cutoff was 10%. The PCa detection rate was significantly greater in subjects with PSADVR >10% than PSADVR ≤10% (28.6% vs. 6.5%, P < 0.001). In addition, PSADVR was the only parameter in this study that showed a significant correlation with mid-to-high-risk PCa (r = 0.63, P = 0.03). Conclusions: Our results demonstrated that PSADVR improved the PCa detection rate on second biopsies, especially for mid-to-high-risk cancers requiring prompt treatment. PMID:27453228

  1. Statistical Considerations in Designing Tests of Mine Detection Systems: II - Measures Related to the False Alarm Rate

    SciTech Connect

    Simonson, K.M.

    1998-08-01

    The rate at which a mine detection system falsely identifies man-made or natural clutter objects as mines is referred to as the system's false alarm rate (FAR). Generally expressed as a rate per unit area or time, the FAR is one of the primary metrics used to gauge system performance. In this report, an overview is given of statistical methods appropriate for the analysis of data relating to FAR. Techniques are presented for determining a suitable size for the clutter collection area, for summarizing the performance of a single sensor, and for comparing different sensors. For readers requiring more thorough coverage of the topics discussed, references to the statistical literature are provided. A companion report addresses statistical issues related to the estimation of mine detection probabilities.

  2. Detection of Clostridium difficile toxins A, B and binary toxin with slow off-rate modified aptamers.

    PubMed

    Ochsner, Urs A; Katilius, Evaldas; Janjic, Nebojsa

    2013-07-01

    Rapid and accurate diagnostic tests for Clostridium difficile infections (CDI) are crucial for management of patients with suspected CDI and for infection control. Enzyme immunoassays for detection of the toxins are routinely used but lack adequate sensitivity. We generated slow off-rate modified aptamers (SOMAmer™ reagents) via in vitro selection (SELEX) that bind toxins A, B and binary toxin with high affinity and specificity. Using SOMAmers alone or in conjunction with antibodies, we have developed toxin assays with a 1 pmol/L (300 pg/mL) limit of detection and a 3 log dynamic range. SOMAmers proved useful as capture or detection agents in equilibrium solution binding radioassays, pull-down capture assays, dot blots, and plate- or membrane-based sandwich assays, thus represent a promising alternative to antibodies in diagnostic applications. SOMAmers detected toxins A, B and binary toxin in culture supernatants from toxigenic C. difficile, including a BI/NAP1 strain and historic strains. PMID:23680240

  3. Incorporation of Slow Off-Rate Modified Aptamers Reagents in Single Molecule Array Assays for Cytokine Detection with Ultrahigh Sensitivity.

    PubMed

    Wu, Danlu; Katilius, Evaldas; Olivas, Edgar; Dumont Milutinovic, Milena; Walt, David R

    2016-09-01

    Slow off-rate modified aptamers (SOMAmers) are attractive protein recognition reagents due to their high binding affinities, stable chemical structures, easy production, and established selection process. Here, biotinylated SOMAmer reagents were incorporated into single molecule array (Simoa)-based assays in place of traditional detection antibodies for six cytokine targets. Optimization and validation were conducted for TNF-α as a demonstration using a capture antibody/detection-SOMAmer detection scheme to highlight the performance of this approach. The optimized assay has a broad dynamic range (>4 log10 units) and an ultralow detection limit of 0.67 fM (0.012 pg/mL). These results show comparable sensitivity to our antibody pair-based Simoa assays, and tens to thousands-fold enhancement in sensitivity compared with conventional ELISAs. High recovery percentages were observed in a spike-recovery test using human sera, demonstrating the feasibility of this novel Simoa assay in detecting TNF-α in clinically relevant samples. Detection SOMAmers were also used to detect other cytokines, such as IFN-γ, IL-1β, IL-2, IL-6, and IL-10, in human samples. Although not yet demonstrated, in principle it should be possible to eventually replace both the capture and detector antibodies with corresponding SOMAmer pairs in sandwich immunoassays. The combination of the ultrasensitive Simoa platform with the higher reliability of SOMAmer binding reagents will greatly benefit both biomarker discovery and disease diagnostic fields. PMID:27529794

  4. Enhanced detection criteria in implantable cardioverter defibrillators: sensitivity and specificity of the stability algorithm at different heart rates.

    PubMed

    Kettering, K; Dörnberger, V; Lang, R; Vonthein, R; Suchalla, R; Bosch, R F; Mewis, C; Eigenberger, B; Kühlkamp, V

    2001-09-01

    The lack of specificity in the detection of ventricular tachyarrhythmias remains a major clinical problem in the therapy with ICDs. The stability criterion has been shown to be useful in discriminating ventricular tachyarrhythmias characterized by a small variation in cycle lengths from AF with rapid ventricular response presenting a higher degree of variability of RR intervals. But RR variability decreases with increasing heart rate during AF. Therefore, the aim of the study was to determine if the sensitivity and specificity of the STABILITY algorithm for spontaneous tachyarrhythmias is related to ventricular rate. Forty-two patients who had received an ICD (CPI Ventak Mini I, II, III or Ventak AV) were enrolled in the study. Two hundred ninety-eight episodes of AF with rapid ventricular response and 817 episodes of ventricular tachyarrhythmias were analyzed. Sensitivity and specificity in the detection of ventricular tachyarrhythmias were calculated at different heart rates. When a stability value of 30 ms was programmed the result was a sensitivity of 82.7% and a specificity of 91.4% in the detection of slow ventricular tachyarrhythmias (heart rate < 150 beats/min). When faster ventricular tachyarrhythmias with rates between 150 and 169 beats/min (170-189 beats/min) were analyzed, a stability value of 30 ms provided a sensitivity of 94.5% (94.7%) and a specificity of 76.5% (54.0%). For arrhythmia episodes > or = 190 beats/min, the same stability value resulted in a sensitivity of 78.2% and a specificity of 41.0%. Even when other stability values were taken into consideration, no acceptable sensitivity/specificity values could be obtained in this subgroup. RR variability decreases with increasing heart rate during AF while RR variability remains almost constant at different cycle lengths during ventricular tachyarrhythmias. Thus, acceptable performance of the STABILITY algorithm appears to be limited to ventricular rate zones < 170 beats/min.

  5. A scale-space method for detecting recurrent DNA copy number changes with analytical false discovery rate control.

    PubMed

    van Dyk, Ewald; Reinders, Marcel J T; Wessels, Lodewyk F A

    2013-05-01

    Tumor formation is partially driven by DNA copy number changes, which are typically measured using array comparative genomic hybridization, SNP arrays and DNA sequencing platforms. Many techniques are available for detecting recurring aberrations across multiple tumor samples, including CMAR, STAC, GISTIC and KC-SMART. GISTIC is widely used and detects both broad and focal (potentially overlapping) recurring events. However, GISTIC performs false discovery rate control on probes instead of events. Here we propose Analytical Multi-scale Identification of Recurrent Events, a multi-scale Gaussian smoothing approach, for the detection of both broad and focal (potentially overlapping) recurring copy number alterations. Importantly, false discovery rate control is performed analytically (no need for permutations) on events rather than probes. The method does not require segmentation or calling on the input dataset and therefore reduces the potential loss of information due to discretization. An important characteristic of the approach is that the error rate is controlled across all scales and that the algorithm outputs a single profile of significant events selected from the appropriate scales. We perform extensive simulations and showcase its utility on a glioblastoma SNP array dataset. Importantly, ADMIRE detects focal events that are missed by GISTIC, including two events involving known glioma tumor-suppressor genes: CDKN2C and NF1.

  6. Transfer Rate Edited experiment for the selective detection of Chemical Exchange via Saturation Transfer (TRE-CEST).

    PubMed

    Friedman, Joshua I; Xia, Ding; Regatte, Ravinder R; Jerschow, Alexej

    2015-07-01

    Chemical Exchange Saturation Transfer (CEST) magnetic resonance experiments have become valuable tools in magnetic resonance for the detection of low concentration solutes with far greater sensitivity than direct detection methods. Accurate measures of rates of chemical exchange provided by CEST are of particular interest to biomedical imaging communities where variations in chemical exchange can be related to subtle variations in biomarker concentration, temperature and pH within tissues using MRI. Despite their name, however, traditional CEST methods are not truly selective for chemical exchange and instead detect all forms of magnetization transfer including through-space NOE. This ambiguity crowds CEST spectra and greatly complicates subsequent data analysis. We have developed a Transfer Rate Edited CEST experiment (TRE-CEST) that uses two different types of solute labeling in order to selectively amplify signals of rapidly exchanging proton species while simultaneously suppressing 'slower' NOE-dominated magnetization transfer processes. This approach is demonstrated in the context of both NMR and MRI, where it is used to detect the labile amide protons of proteins undergoing chemical exchange (at rates⩾30s(-1)) while simultaneously eliminating signals originating from slower (∼5s(-1)) NOE-mediated magnetization transfer processes. TRE-CEST greatly expands the utility of CEST experiments in complex systems, and in-vivo, in particular, where it is expected to improve the quantification of chemical exchange and magnetization transfer rates while enabling new forms of imaging contrast. PMID:25996515

  7. DSP implementation of wavelet transform for real time ECG wave forms detection and heart rate analysis.

    PubMed

    Bahoura, M; Hassani, M; Hubin, M

    1997-01-01

    An algorithm based on wavelet transform (WTs) suitable for real time implementation has been developed in order to detect ECG characteristics. In particular, QRS complexes, P and T waves may be distinguished from noise, baseline drift or artefacts. This algorithm is implemented in a DSP (SPROC-1400) with a 50 MHz frequency clock. The performance of this algorithm is discussed, its accuracy is evaluated and a comparison is made with a similar algorithm implemented in C language. For the standard MIT/BIH arrhythmia database, this algorithm correctly detects 99.7% of the QRS complexes. PMID:9034668

  8. Simultaneous estimation of b-values and detection rates of earthquakes for the application to aftershock probability forecasting

    NASA Astrophysics Data System (ADS)

    Katsura, K.; Ogata, Y.

    2004-12-01

    Reasenberg and Jones [Science, 1989, 1994] proposed the aftershock probability forecasting based on the joint distribution [Utsu, J. Fac. Sci. Hokkaido Univ., 1970] of the modified Omori formula of aftershock decay and Gutenberg-Richter law of magnitude frequency, where the respective parameters are estimated by the maximum likelihood method [Ogata, J. Phys. Earth, 1983; Utsu, Geophys Bull. Hokkaido Univ., 1965, Aki, Bull. Earthq. Res. Inst., 1965]. The public forecast has been implemented by the responsible agencies in California and Japan. However, a considerable difficulty in the above procedure is that, due to the contamination of arriving seismic waves, detection rate of aftershocks is extremely low during a period immediately after the main shock, say, during the first day, when the forecasting is most critical for public in the affected area. Therefore, for the forecasting of a probability during such a period, they adopt a generic model with a set of the standard parameter values in California or Japan. For an effective and realistic estimation, I propose to utilize the statistical model introduced by Ogata and Katsura [Geophys. J. Int., 1993] for the simultaneous estimation of the b-values of Gutenberg-Richter law together with detection-rate (probability) of earthquakes of each magnitude-band from the provided data of all detected events, where the both parameters are allowed for changing in time. Thus, by using all detected aftershocks from the beginning of the period, we can estimate the underlying modified Omori rate of both detected and undetected events and their b-value changes, taking the time-varying missing rates of events into account. The similar computation is applied to the ETAS model for complex aftershock activity or regional seismicity where substantial missing events are expected immediately after a large aftershock or another strong earthquake in the vicinity. Demonstrations of the present procedure will be shown for the recent examples

  9. Slip-rate increase at Parkfield in 1993 detected by high-precision EDM and borehole tensor strainmeters

    USGS Publications Warehouse

    Langbein, J.; Gwyther, R.L.; Hart, R.H.G.; Gladwin, M.T.

    1999-01-01

    On two of the instrument networks at Parkfield, California, the two-color Electronic Distance Meter (EDM) network and Borehole Tensor Strainmeter (BTSM) network, we have detected a rate change starting in 1993 that has persisted at least 5 years. These and other instruments capable of measuring crustal deformation were installed at Parkfield in anticipation of a moderate, M6, earthquake on the San Andreas fault. Many of these instruments have been in operation since the mid 1980s and have established an excellent baseline to judge changes in rate of deformation and the coherence of such changes between instruments. The onset of the observed rate change corresponds in time to two other changes at Parkfield. From late 1992 through late 1994, the Parkfield region had an increase in number of M4 to M5 earthquakes relative to the preceding 6 years. The deformation-rate change also coincides with the end of a 7-year period of sub-normal rainfall. Both the spatial coherence of the rate change and hydrological modeling suggest a tectonic explanation for the rate change. From these observations, we infer that the rate of slip increased over the period 1993-1998.On two of the instrument networks at Parkfield, California, the two-color Electronic Distance Meter (EDM) network and Borehole Tensor Strainmeter (BTSM) network, we have detected a rate change starting in 1993 that has persisted at least 5 years. These and other instruments capable of measuring crustal deformation were installed at Parkfield in anticipation of a moderate, M6, earthquake on the San Andreas fault. Many of these instruments have been in operation since the mid 1980s and have established an excellent baseline to judge changes in rate of deformation and the coherence of such changes between instruments. The onset of the observed rate change corresponds in time to two other changes at Parkfield. From late 1992 through late 1994, the Parkfield region had an increase in number of M4 to M5 earthquakes

  10. Effect of the Brazilian Conditional Cash Transfer and Primary Health Care Programs on the New Case Detection Rate of Leprosy

    PubMed Central

    Nery, Joilda Silva; Pereira, Susan Martins; Rasella, Davide; Penna, Maria Lúcia Fernandes; Aquino, Rosana; Rodrigues, Laura Cunha; Barreto, Mauricio Lima; Penna, Gerson Oliveira

    2014-01-01

    Background Social determinants can affect the transmission of leprosy and its progression to disease. Not much is known about the effectiveness of welfare and primary health care policies on the reduction of leprosy occurrence. The aim of this study is to evaluate the impact of the Brazilian cash transfer (Bolsa Família Program-BFP) and primary health care (Family Health Program-FHP) programs on new case detection rate of leprosy. Methodology/Principal Findings We conducted the study with a mixed ecological design, a combination of an ecological multiple-group and time-trend design in the period 2004–2011 with the Brazilian municipalities as unit of analysis. The main independent variables were the BFP and FHP coverage at the municipal level and the outcome was new case detection rate of leprosy. Leprosy new cases, BFP and FHP coverage, population and other relevant socio-demographic covariates were obtained from national databases. We used fixed-effects negative binomial models for panel data adjusted for relevant socio-demographic covariates. A total of 1,358 municipalities were included in the analysis. In the studied period, while the municipal coverage of BFP and FHP increased, the new case detection rate of leprosy decreased. Leprosy new case detection rate was significantly reduced in municipalities with consolidated BFP coverage (Risk Ratio 0.79; 95% CI  = 0.74–0.83) and significantly increased in municipalities with FHP coverage in the medium (72–95%) (Risk Ratio 1.05; 95% CI  = 1.02–1.09) and higher coverage tertiles (>95%) (Risk Ratio 1.12; 95% CI  = 1.08–1.17). Conclusions At the same time the Family Health Program had been effective in increasing the new case detection rate of leprosy in Brazil, the Bolsa Família Program was associated with a reduction of the new case detection rate of leprosy that we propose reflects a reduction in leprosy incidence. PMID:25412418

  11. Simultaneous Use of Multiple Answer Copying Indexes to Improve Detection Rates

    ERIC Educational Resources Information Center

    Wollack, James A.

    2006-01-01

    Many of the currently available statistical indexes to detect answer copying lack sufficient power at small [alpha] levels or when the amount of copying is relatively small. Furthermore, there is no one index that is uniformly best. Depending on the type or amount of copying, certain indexes are better than others. The purpose of this article was…

  12. Supernova relic neutrinos and the supernova rate problem: Analysis of uncertainties and detectability of ONeMg and failed supernovae

    SciTech Connect

    Mathews, Grant J.; Hidaka, Jun; Kajino, Toshitaka; Suzuki, Jyutaro

    2014-08-01

    Direct measurements of the core collapse supernova rate (R{sub SN}) in the redshift range 0 ≤ z ≤ 1 appear to be about a factor of two smaller than the rate inferred from the measured cosmic massive star formation rate (SFR). This discrepancy would imply that about one-half of the massive stars that have been born in the local observed comoving volume did not explode as luminous supernovae. In this work, we explore the possibility that one could clarify the source of this 'supernova rate problem' by detecting the energy spectrum of supernova relic neutrinos with a next generation 10{sup 6} ton water Čerenkov detector like Hyper-Kamiokande. First, we re-examine the supernova rate problem. We make a conservative alternative compilation of the measured SFR data over the redshift range 0 ≤z ≤ 7. We show that by only including published SFR data for which the dust obscuration has been directly determined, the ratio of the observed massive SFR to the observed supernova rate R{sub SN} has large uncertainties ∼1.8{sub −0.6}{sup +1.6} and is statistically consistent with no supernova rate problem. If we further consider that a significant fraction of massive stars will end their lives as faint ONeMg SNe or as failed SNe leading to a black hole remnant, then the ratio reduces to ∼1.1{sub −0.4}{sup +1.0} and the rate problem is essentially solved. We next examine the prospects for detecting this solution to the supernova rate problem. We first study the sources of uncertainty involved in the theoretical estimates of the neutrino detection rate and analyze whether the spectrum of relic neutrinos can be used to independently identify the existence of a supernova rate problem and its source. We consider an ensemble of published and unpublished core collapse supernova simulation models to estimate the uncertainties in the anticipated neutrino luminosities and temperatures. We illustrate how the spectrum of detector events might be used to establish the average

  13. How Well Can We Detect Lineage-Specific Diversification-Rate Shifts? A Simulation Study of Sequential AIC Methods

    PubMed Central

    May, Michael R.; Moore, Brian R.

    2016-01-01

    Evolutionary biologists have long been fascinated by the extreme differences in species numbers across branches of the Tree of Life. This has motivated the development of statistical methods for detecting shifts in the rate of lineage diversification across the branches of phylogenic trees. One of the most frequently used methods, MEDUSA, explores a set of diversification-rate models, where each model assigns branches of the phylogeny to a set of diversification-rate categories. Each model is first fit to the data, and the Akaike information criterion (AIC) is then used to identify the optimal diversification model. Surprisingly, the statistical behavior of this popular method is uncharacterized, which is a concern in light of: (1) the poor performance of the AIC as a means of choosing among models in other phylogenetic contexts; (2) the ad hoc algorithm used to visit diversification models, and; (3) errors that we reveal in the likelihood function used to fit diversification models to the phylogenetic data. Here, we perform an extensive simulation study demonstrating that MEDUSA (1) has a high false-discovery rate (on average, spurious diversification-rate shifts are identified ≈30% of the time), and (2) provides biased estimates of diversification-rate parameters. Understanding the statistical behavior of MEDUSA is critical both to empirical researchers—in order to clarify whether these methods can make reliable inferences from empirical datasets—and to theoretical biologists—in order to clarify the specific problems that need to be solved in order to develop more reliable approaches for detecting shifts in the rate of lineage diversification. [Akaike information criterion; extinction; lineage-specific diversification rates; phylogenetic model selection; speciation.] PMID:27037081

  14. Heart Rate Variability for the Early Detection of Delayed Cerebral Ischemia.

    PubMed

    Schmidt, J Michael

    2016-06-01

    Delayed cerebral ischemia is considered the leading cause of death or major disability in subarachnoid hemorrhage after the impact of the initial event and rebleeding. Waiting to treat patients until they exhibit clinical symptoms of ischemia is too late to prevent cerebral infarction for more than 60% of patients, and transcranial Doppler ultrasonography has not proven to be a reliable screening tool to identify high-risk patients. Continuous heart rate variability monitoring may provide an alternative screening strategy to identify patients at high risk for delayed cerebral ischemia. Heart rate variability is a composite reflection of autonomic outflow, neuroendocrine influences, and autonomic responsiveness. Most importantly, heart rate variability is responsive to changes in systemic inflammation, which evidence suggests is important to the causal pathway of delayed cerebral ischemia. The clinical application of continuous heart rate variability monitoring in critical care is relatively recent despite its existence for more than 50 years. Initial studies suggest promise for heart rate variability monitoring as a delayed cerebral ischemia screening tool, but significant research is still required before this approach may achieve clinical applicability and bring benefit to patients. PMID:27258451

  15. Detecting differential rater functioning over time (DRIFT) using a Rasch multi-faceted rating scale model.

    PubMed

    Wolfe, E W; Moulder, B C; Myford, C M

    2001-01-01

    This paper describes a class of rater effects that depict rater-by-time interactions. We refer to this class of rater effects as DRIFT differential rater functioning over time. This article describes several types of DRIFT (primacy/recency, differential centrality/extremism, and practice/fatigue) and Rasch measurement procedures designed to identify these types of DRIFT in rating data. These procedures are applied to simulated data and are shown to be useful in classifying raters as being aberrant or non-aberrant for primacy, recency, and differential centrality and extremism, particularly for moderate or larger effect sizes. Rates of correct classification for practice and fatigue were lower and statistical power exceeded.50 only with very large effect sizes. Type I error rates (i.e., incorrect nomination) were near expected levels in all cases.

  16. Gait event detection on level ground and incline walking using a rate gyroscope.

    PubMed

    Catalfamo, Paola; Ghoussayni, Salim; Ewins, David

    2010-01-01

    Gyroscopes have been proposed as sensors for ambulatory gait analysis and functional electrical stimulation systems. Accurate determination of the Initial Contact of the foot with the floor (IC) and the final contact or Foot Off (FO) on different terrains is important. This paper describes the evaluation of a gyroscope placed on the shank for determination of IC and FO in subjects walking outdoors on level ground, and up and down an incline. Performance was compared with a reference pressure measurement system. The mean difference between the gyroscope and the reference was less than -25 ms for IC and less than 75 ms for FO for all terrains. Detection success was over 98%. These results provide preliminary evidence supporting the use of the gyroscope for gait event detection on inclines as well as level walking.

  17. Gait Event Detection on Level Ground and Incline Walking Using a Rate Gyroscope

    PubMed Central

    Catalfamo, Paola; Ghoussayni, Salim; Ewins, David

    2010-01-01

    Gyroscopes have been proposed as sensors for ambulatory gait analysis and functional electrical stimulation systems. Accurate determination of the Initial Contact of the foot with the floor (IC) and the final contact or Foot Off (FO) on different terrains is important. This paper describes the evaluation of a gyroscope placed on the shank for determination of IC and FO in subjects walking outdoors on level ground, and up and down an incline. Performance was compared with a reference pressure measurement system. The mean difference between the gyroscope and the reference was less than −25 ms for IC and less than 75 ms for FO for all terrains. Detection success was over 98%. These results provide preliminary evidence supporting the use of the gyroscope for gait event detection on inclines as well as level walking. PMID:22219682

  18. Simultaneous detection of tissue autofluorescence decay distribution and time-gated photo-bleaching rates

    NASA Astrophysics Data System (ADS)

    Lihachev, Alexey; Ferulova, Inesa; Spigulis, Janis; Tamosiunas, Mindaugas

    2015-05-01

    Experimental methodology for parallel measurements of in-vivo skin autofluorescence (AF) lifetimes and photobleaching dynamic has been developed and tested. The AF lifetime decay distributions were periodically collected from fixed tissue area with subsequent detection of the fluorescence intensity decrease dynamic at different time gates after the pulse excitation. Temporal distributions of human in-vivo skin AF lifetimes and bleaching kinetics were collected and analyzed by means of commercial time-correlated single photon counting system.

  19. RS slope detection algorithm for extraction of heart rate from noisy, multimodal recordings.

    PubMed

    Gierałtowski, Jan; Ciuchciński, Kamil; Grzegorczyk, Iga; Kośna, Katarzyna; Soliński, Mateusz; Podziemski, Piotr

    2015-08-01

    Current gold-standard algorithms for heart beat detection do not work properly in the case of high noise levels and do not make use of multichannel data collected by modern patient monitors. The main idea behind the method presented in this paper is to detect the most prominent part of the QRS complex, i.e. the RS slope. We localize the RS slope based on the consistency of its characteristics, i.e. adequate, automatically determined amplitude and duration. It is a very simple and non-standard, yet very effective, solution. Minor data pre-processing and parameter adaptations make our algorithm fast and noise-resistant. As one of a few algorithms in the PhysioNet/Computing in Cardiology Challenge 2014, our algorithm uses more than two channels (i.e. ECG, BP, EEG, EOG and EMG). Simple fundamental working rules make the algorithm universal: it is able to work on all of these channels with no or only little changes. The final result of our algorithm in phase III of the Challenge was 86.38 (88.07 for a 200 record test set), which gave us fourth place. Our algorithm shows that current standards for heart beat detection could be improved significantly by taking a multichannel approach. This is an open-source algorithm available through the PhysioNet library.

  20. Biochemical Detection and Identification False Alarm Rate Dependence on Wavelength Using Laser Induced Fluorescence

    NASA Technical Reports Server (NTRS)

    Bhartia, R.; Hug, W. F.; Sala, E. C.; Sijapati, K.; Lane, A. L.; Reid, R. D.; Conrad, P. G.

    2006-01-01

    Most organic and many inorganic materials absorb strongly in specific wavelength ranges in the deep UV between about 220nm and 300nm. Excitation within these absorption bands results in native fluorescence emission. Each compound or composite material, such as a bacterial spore, has a unique excitation-emission fingerprint that can be used to provide information about the material. The sensitivity and specificity with which these materials can be detected and identified depends on the excitation wavelength and the number and location of observation wavelengths.We will present data on our deep ultraviolet Targeted Ultraviolet Chemical Sensors that demonstrate the sensitivity and specificity of the sensors. In particular, we will demonstrate the ability to quantitatively differentiate a wide range of biochemical agent targets against a wide range of background materials. We will describe the relationship between spectral resolution and specificity in target identification, as well as simple, fast, algorithms to identify materials.Hand-held, battery operated instruments using a deep UV laser and multi-band detection have been developed and deployed on missions to the Antarctic, the Arctic, and the deep ocean with the capability of detecting a single bacterial spore and to differentiate a wide range of organic and biological compounds.

  1. Detecting Differential Rater Functioning over Time (DRIFT) Using a Rasch Multi-faceted Rating Scale Model.

    ERIC Educational Resources Information Center

    Wolfe, Edward W.; Moulder, Bradley C.; Myford, Carol M.

    2001-01-01

    Describes a class of rater effects, differential rater functioning over time (DRIFT), that depicts rater-by-time interactions. Also describes Rasch measurement procedures designed to identify these types of DRIFT in rating data. Applied these procedures to simulated data to show their usefulness in classifying raters as aberrant or non-aberrant…

  2. Respiratory rate detection algorithm based on RGB-D camera: theoretical background and experimental results

    PubMed Central

    Freddi, Alessandro; Monteriù, Andrea; Longhi, Sauro

    2014-01-01

    Both the theoretical background and the experimental results of an algorithm developed to perform human respiratory rate measurements without any physical contact are presented. Based on depth image sensing techniques, the respiratory rate is derived by measuring morphological changes of the chest wall. The algorithm identifies the human chest, computes its distance from the camera and compares this value with the instantaneous distance, discerning if it is due to the respiratory act or due to a limited movement of the person being monitored. To experimentally validate the proposed algorithm, the respiratory rate measurements coming from a spirometer were taken as a benchmark and compared with those estimated by the algorithm. Five tests were performed, with five different persons sat in front of the camera. The first test aimed to choose the suitable sampling frequency. The second test was conducted to compare the performances of the proposed system with respect to the gold standard in ideal conditions of light, orientation and clothing. The third, fourth and fifth tests evaluated the algorithm performances under different operating conditions. The experimental results showed that the system can correctly measure the respiratory rate, and it is a viable alternative to monitor the respiratory activity of a person without using invasive sensors. PMID:26609383

  3. Automatic detection of key innovations, rate shifts, and diversity-dependence on phylogenetic trees.

    PubMed

    Rabosky, Daniel L

    2014-01-01

    A number of methods have been developed to infer differential rates of species diversification through time and among clades using time-calibrated phylogenetic trees. However, we lack a general framework that can delineate and quantify heterogeneous mixtures of dynamic processes within single phylogenies. I developed a method that can identify arbitrary numbers of time-varying diversification processes on phylogenies without specifying their locations in advance. The method uses reversible-jump Markov Chain Monte Carlo to move between model subspaces that vary in the number of distinct diversification regimes. The model assumes that changes in evolutionary regimes occur across the branches of phylogenetic trees under a compound Poisson process and explicitly accounts for rate variation through time and among lineages. Using simulated datasets, I demonstrate that the method can be used to quantify complex mixtures of time-dependent, diversity-dependent, and constant-rate diversification processes. I compared the performance of the method to the MEDUSA model of rate variation among lineages. As an empirical example, I analyzed the history of speciation and extinction during the radiation of modern whales. The method described here will greatly facilitate the exploration of macroevolutionary dynamics across large phylogenetic trees, which may have been shaped by heterogeneous mixtures of distinct evolutionary processes. PMID:24586858

  4. Response and Remission in Adolescent Mania: Signal Detection Analyses of the Young Mania Rating Scale

    ERIC Educational Resources Information Center

    Patel, Nick C.; Patrick, Danielle M.; Youngstrom, Eric A.; Strakowski, Stephen M.; Delbello, Melissa P.

    2007-01-01

    Objective: The purpose of this study was to determine optimal criteria for defining response and remission in adolescents with acute mania. Method: Data were analyzed from three treatment studies of adolescents with acute mania (N = 99). Trained raters completed the Young Mania Rating Scale (YMRS), and clinicians completed the Clinical Global…

  5. Children with Autism Detect Targets at Very Rapid Presentation Rates with Similar Accuracy as Adults

    ERIC Educational Resources Information Center

    Hagmann, Carl Erick; Wyble, Bradley; Shea, Nicole; LeBlanc, Megan; Kates, Wendy R.; Russo, Natalie

    2016-01-01

    Enhanced perception may allow for visual search superiority by individuals with Autism Spectrum Disorder (ASD), but does it occur over time? We tested high-functioning children with ASD, typically developing (TD) children, and TD adults in two tasks at three presentation rates (50, 83.3, and 116.7 ms/item) using rapid serial visual presentation.…

  6. The Detection Rate of Early UV Emission from Supernovae: A Dedicated Galex/PTF Survey and Calibrated Theoretical Estimates

    NASA Astrophysics Data System (ADS)

    Ganot, Noam; Gal-Yam, Avishay; Ofek, Eran. O.; Sagiv, Ilan; Waxman, Eli; Lapid, Ofer; Kulkarni, Shrinivas R.; Ben-Ami, Sagi; Kasliwal, Mansi M.; The ULTRASAT Science Team; Chelouche, Doron; Rafter, Stephen; Behar, Ehud; Laor, Ari; Poznanski, Dovi; Nakar, Ehud; Maoz, Dan; Trakhtenbrot, Benny; WTTH Consortium, The; Neill, James D.; Barlow, Thomas A.; Martin, Christofer D.; Gezari, Suvi; the GALEX Science Team; Arcavi, Iair; Bloom, Joshua S.; Nugent, Peter E.; Sullivan, Mark; Palomar Transient Factory, The

    2016-03-01

    The radius and surface composition of an exploding massive star, as well as the explosion energy per unit mass, can be measured using early UV observations of core-collapse supernovae (SNe). We present the first results from a simultaneous GALEX/PTF search for early ultraviolet (UV) emission from SNe. Six SNe II and one Type II superluminous SN (SLSN-II) are clearly detected in the GALEX near-UV (NUV) data. We compare our detection rate with theoretical estimates based on early, shock-cooling UV light curves calculated from models that fit existing Swift and GALEX observations well, combined with volumetric SN rates. We find that our observations are in good agreement with calculated rates assuming that red supergiants (RSGs) explode with fiducial radii of 500 R ⊙, explosion energies of 1051 erg, and ejecta masses of 10 M ⊙. Exploding blue supergiants and Wolf-Rayet stars are poorly constrained. We describe how such observations can be used to derive the progenitor radius, surface composition, and explosion energy per unit mass of such SN events, and we demonstrate why UV observations are critical for such measurements. We use the fiducial RSG parameters to estimate the detection rate of SNe during the shock-cooling phase (<1 day after explosion) for several ground-based surveys (PTF, ZTF, and LSST). We show that the proposed wide-field UV explorer ULTRASAT mission is expected to find >85 SNe per year (˜0.5 SN per deg2), independent of host galaxy extinction, down to an NUV detection limit of 21.5 mag AB. Our pilot GALEX/PTF project thus convincingly demonstrates that a dedicated, systematic SN survey at the NUV band is a compelling method to study how massive stars end their life.

  7. Detection rate and prognostic value of circulating tumor cells and circulating tumor DNA in metastatic uveal melanoma.

    PubMed

    Bidard, François-Clément; Madic, Jordan; Mariani, Pascale; Piperno-Neumann, Sophie; Rampanou, Aurore; Servois, Vincent; Cassoux, Nathalie; Desjardins, Laurence; Milder, Maud; Vaucher, Isabelle; Pierga, Jean-Yves; Lebofsky, Ronald; Stern, Marc-Henri; Lantz, Olivier

    2014-03-01

    Circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) have been recently investigated in several cancer types, but their respective clinical significance remains to be determined. In our prospective study, we compared the detection rate and the prognostic value of these two circulating biomarkers in patients with metastatic uveal melanoma. GNAQ/GNA11 mutations were characterized in archived tumor tissue. Using a highly sensitive and mutation-specific bidirectional pyrophosphorolysis-activated polymerization (bi-PAP) technique, GNAQ c.626A>T, GNAQ c.626A>C and GNA11 c.626A>T copy numbers were quantified in plasma from 12 mL of blood. CTCs were detected at the same time in 7.5 mL of blood by the CellSearch technique. Patient characteristics and outcome were prospectively collected. CTCs (≥1) were detected in 12 of the 40 included patients (30%, range 1-20). Among the 26 patients with known detectable mutations, ctDNA was detected and quantified in 22 (84%, range 4-11,421 copies/mL). CTC count and ctDNA levels were associated with the presence of miliary hepatic metastasis (p = 0.004 and 0.03, respectively), with metastasis volume (p = 0.005 and 0.004) and with each other (p < 0.0001). CTC count and ctDNA levels were both strongly associated with progression-free survival (p = 0.003 and 0.001) and overall survival (p = 0.0009 and <0.0001). In multivariate analyses, ctDNA appeared to be a better prognostic marker than CTC. In conclusion, ctDNA and CTC are correlated and both have poor prognostic significance. CTC detection can be performed in every patient but, in patients with detectable mutations, ctDNA was more frequently detected than CTC and has possibly more prognostic value.

  8. Nonlinear Heart Rate Variability features for real-life stress detection. Case study: students under stress due to university examination

    PubMed Central

    2011-01-01

    Background This study investigates the variations of Heart Rate Variability (HRV) due to a real-life stressor and proposes a classifier based on nonlinear features of HRV for automatic stress detection. Methods 42 students volunteered to participate to the study about HRV and stress. For each student, two recordings were performed: one during an on-going university examination, assumed as a real-life stressor, and one after holidays. Nonlinear analysis of HRV was performed by using Poincaré Plot, Approximate Entropy, Correlation dimension, Detrended Fluctuation Analysis, Recurrence Plot. For statistical comparison, we adopted the Wilcoxon Signed Rank test and for development of a classifier we adopted the Linear Discriminant Analysis (LDA). Results Almost all HRV features measuring heart rate complexity were significantly decreased in the stress session. LDA generated a simple classifier based on the two Poincaré Plot parameters and Approximate Entropy, which enables stress detection with a total classification accuracy, a sensitivity and a specificity rate of 90%, 86%, and 95% respectively. Conclusions The results of the current study suggest that nonlinear HRV analysis using short term ECG recording could be effective in automatically detecting real-life stress condition, such as a university examination. PMID:22059697

  9. Macrolide Resistance of Mycoplasma pneumoniae and Its Detection Rate by Real-Time PCR in Primary and Tertiary Care Hospitals

    PubMed Central

    Hong, Joo Hee; Oh, Ki Jin; Cho, Hyun Mi; Park, Soon Deok; Kim, Juwon; Yoon, Kap Jun

    2013-01-01

    Background This study aimed to evaluate the prevalence of Mycoplasma pneumoniae in primary and tertiary care hospitals and its macrolide resistance rate. Methods Nasopharyngeal swabs were collected from 195 pediatric patients in primary and tertiary care hospitals from October to November 2010. The AccuPower MP real-time PCR kit (Bioneer, Korea) was used for the detection of M. pneumoniae. Direct amplicon sequencing was performed to detect point mutations conferring resistance to macrolides in the 23S rRNA gene. Results Among the 195 specimens, 17 (8.7%) were M. pneumoniae positive, and 3 of the strains (17.6%) obtained from these 17 specimens displayed the A2063G mutation in 23S rRNA. Three macrolide-resistant M. pneumoniae isolates were isolated from patients hospitalized at the primary care hospital. The positive rates of M. pneumoniae for the primary and tertiary care hospitals were 12.1% (15/124) and 2.8% (2/71), respectively (P=0.033). Conclusions The positive rate of M. pneumoniae in the primary care hospital was higher than that in the tertiary care hospital. Simultaneous detection of M. pneumoniae and macrolide-resistant mutation genes in the 23S rRNA by real-time PCR is needed for rapid diagnosis and therapy of M. pneumoniae infections. PMID:24205489

  10. Lock-in-detection-free line-scan stimulated Raman scattering microscopy for near video-rate Raman imaging.

    PubMed

    Wang, Zi; Zheng, Wei; Huang, Zhiwei

    2016-09-01

    We report on the development of a unique lock-in-detection-free line-scan stimulated Raman scattering microscopy technique based on a linear detector with a large full well capacity controlled by a field-programmable gate array (FPGA) for near video-rate Raman imaging. With the use of parallel excitation and detection scheme, the line-scan SRS imaging at 20 frames per second can be acquired with a ∼5-fold lower excitation power density, compared to conventional point-scan SRS imaging. The rapid data communication between the FPGA and the linear detector allows a high line-scanning rate to boost the SRS imaging speed without the need for lock-in detection. We demonstrate this lock-in-detection-free line-scan SRS imaging technique using the 0.5 μm polystyrene and 1.0 μm poly(methyl methacrylate) beads mixed in water, as well as living gastric cancer cells.

  11. Lock-in-detection-free line-scan stimulated Raman scattering microscopy for near video-rate Raman imaging.

    PubMed

    Wang, Zi; Zheng, Wei; Huang, Zhiwei

    2016-09-01

    We report on the development of a unique lock-in-detection-free line-scan stimulated Raman scattering microscopy technique based on a linear detector with a large full well capacity controlled by a field-programmable gate array (FPGA) for near video-rate Raman imaging. With the use of parallel excitation and detection scheme, the line-scan SRS imaging at 20 frames per second can be acquired with a ∼5-fold lower excitation power density, compared to conventional point-scan SRS imaging. The rapid data communication between the FPGA and the linear detector allows a high line-scanning rate to boost the SRS imaging speed without the need for lock-in detection. We demonstrate this lock-in-detection-free line-scan SRS imaging technique using the 0.5 μm polystyrene and 1.0 μm poly(methyl methacrylate) beads mixed in water, as well as living gastric cancer cells. PMID:27607947

  12. Detecting psychological distress among patients attending secondary health care clinics. Self-report and physician rating.

    PubMed

    Feldman, D; Rabinowitz, J; Ben Yehuda, Y

    1995-11-01

    A study was conducted to determine the prevalence of psychological distress, as reported by patients and their physicians, in orthopedic, neurology, dermatology, and ophthalmology clinics; to study their accuracy in detecting psychological distress; and to determine if there is any connection among psychological distress, accuracy of detecting distress, and use of mental health and primary health care physicians' prognosis for the somatic complaints. Five hundred and fifty-six patients, ages 18-21, responded to the Psychiatric Epidemiology Research Interview Demoralization Scale (PERI-D), a measure of psychological distress, and to questions about their mental health and use of mental health and primary health services. Physicians, who were blind to patients' responses, were asked to what extent they thought the cause of patients' complaints was physical and to what extent they thought it was psychological in nature, and to prognosticate. Based on the PERI-D, about 25% of patients were distressed, this was less for females than males and varied between clinics. Based on self-reporting, about 14% of patients (males and females) were distressed. Based on physician reporting, about 17% (males less) were distressed. Physicians identified 35% of the PERI-D-distressed cases and 79% of nondistressed cases. About 66% of patients identified their distress and 83% their lack of distress. Increased use of primary health care and mental health care was related to distress. The prognosis was negatively related to distress. Based on this study, there is a need for more attention to psychological distress among secondary health care patients. Patients' ability to identify their distress suggests the importance of involving the patient in the diagnostic process. Correct detection of distress alone does not appear to decrease the use of primary medical and mental health services. PMID:8714802

  13. Penguin head movement detected using small accelerometers: a proxy of prey encounter rate.

    PubMed

    Kokubun, Nobuo; Kim, Jeong-Hoon; Shin, Hyoung-Chul; Naito, Yasuhiko; Takahashi, Akinori

    2011-11-15

    Determining temporal and spatial variation in feeding rates is essential for understanding the relationship between habitat features and the foraging behavior of top predators. In this study we examined the utility of head movement as a proxy of prey encounter rates in medium-sized Antarctic penguins, under the presumption that the birds should move their heads actively when they encounter and peck prey. A field study of free-ranging chinstrap and gentoo penguins was conducted at King George Island, Antarctica. Head movement was recorded using small accelerometers attached to the head, with simultaneous monitoring for prey encounter or body angle. The main prey was Antarctic krill (>99% in wet mass) for both species. Penguin head movement coincided with a slow change in body angle during dives. Active head movements were extracted using a high-pass filter (5 Hz acceleration signals) and the remaining acceleration peaks (higher than a threshold acceleration of 1.0 g) were counted. The timing of head movements coincided well with images of prey taken from the back-mounted cameras: head movement was recorded within ±2.5 s of a prey image on 89.1±16.1% (N=7 trips) of images. The number of head movements varied largely among dive bouts, suggesting large temporal variations in prey encounter rates. Our results show that head movement is an effective proxy of prey encounter, and we suggest that the method will be widely applicable for a variety of predators.

  14. A halo-independent lower bound on the dark matter capture rate in the Sun from a direct detection signal

    SciTech Connect

    Blennow, Mattias; Herrero-Garcia, Juan; Schwetz, Thomas

    2015-05-21

    We show that a positive signal in a dark matter (DM) direct detection experiment can be used to place a lower bound on the DM capture rate in the Sun, independent of the DM halo. For a given particle physics model and DM mass we obtain a lower bound on the capture rate independent of the local DM density, velocity distribution, galactic escape velocity, as well as the scattering cross section. We illustrate this lower bound on the capture rate by assuming that upcoming direct detection experiments will soon obtain a significant signal. When comparing the lower bound on the capture rate with limits on the high-energy neutrino flux from the Sun from neutrino telescopes, we can place upper limits on the branching fraction of DM annihilation channels leading to neutrinos. With current data from IceCube and Super-Kamiokande non-trivial limits can be obtained for spin-dependent interactions and direct annihilations into neutrinos. In some cases also annihilations into ττ or bb start getting constrained. For spin-independent interactions current constraints are weak, but they may become interesting for data from future neutrino telescopes.

  15. A halo-independent lower bound on the dark matter capture rate in the Sun from a direct detection signal

    SciTech Connect

    Blennow, Mattias; Herrero-Garcia, Juan; Schwetz, Thomas E-mail: juhg@kth.se

    2015-05-01

    We show that a positive signal in a dark matter (DM) direct detection experiment can be used to place a lower bound on the DM capture rate in the Sun, independent of the DM halo. For a given particle physics model and DM mass we obtain a lower bound on the capture rate independent of the local DM density, velocity distribution, galactic escape velocity, as well as the scattering cross section. We illustrate this lower bound on the capture rate by assuming that upcoming direct detection experiments will soon obtain a significant signal. When comparing the lower bound on the capture rate with limits on the high-energy neutrino flux from the Sun from neutrino telescopes, we can place upper limits on the branching fraction of DM annihilation channels leading to neutrinos. With current data from IceCube and Super-Kamiokande non-trivial limits can be obtained for spin-dependent interactions and direct annihilations into neutrinos. In some cases also annihilations into ττ or b b start getting constrained. For spin-independent interactions current constraints are weak, but they may become interesting for data from future neutrino telescopes.

  16. Automatic detection of rate change in large data sets with an unsupervised approach: the case of influenza viruses.

    PubMed

    Labonté, Kasandra; Aris-Brosou, Stéphane

    2016-04-01

    Influenza viruses evolve at such a high rate that vaccine recommendations need to be changed, but not quite on a regular basis. This observation suggests that the rate of evolution of these viruses is not constant through time, which begs the question as to when such rate changes occur, if they do so independently of the host in which they circulate and (or) independently of their subtype. To address these outstanding questions, we introduce a novel heuristics, Mclust*, that is based on a two-tier clustering approach in a phylogenetic context to estimate (i) absolute rates of evolution and (ii) when rate change occurs. We employ the novel approach to compare the two influenza surface proteins, hemagglutinin and neuraminidase, that circulated in avian, human, and swine hosts between 1960 and 2014 in two subtypes: H3N2 and H1N1. We show that the algorithm performs well in most conditions, accounting for phylogenetic uncertainty by means of bootstrapping and scales up to analyze very large data sets. Our results show that our approach is robust to the time-dependent artifact of rate estimation, and confirm pervasive punctuated evolution across hosts and subtypes. As such, the novel approach can potentially detect when vaccine composition needs to be updated. PMID:26966881

  17. The Limits of Coding with Joint Constraints on Detected and Undetected Error Rates

    NASA Technical Reports Server (NTRS)

    Dolinar, Sam; Andrews, Kenneth; Pollara, Fabrizio; Divsalar, Dariush

    2008-01-01

    We develop a remarkably tight upper bound on the performance of a parameterized family of bounded angle maximum-likelihood (BA-ML) incomplete decoders. The new bound for this class of incomplete decoders is calculated from the code's weight enumerator, and is an extension of Poltyrev-type bounds developed for complete ML decoders. This bound can also be applied to bound the average performance of random code ensembles in terms of an ensemble average weight enumerator. We also formulate conditions defining a parameterized family of optimal incomplete decoders, defined to minimize both the total codeword error probability and the undetected error probability for any fixed capability of the decoder to detect errors. We illustrate the gap between optimal and BA-ML incomplete decoding via simulation of a small code.

  18. Dual Site Sampling Improved Detection Rates for MRSA Colonization in Patients with Cutaneous Abscesses

    PubMed Central

    May, L.; McCann, C.; Brooks, G.; Rothman, R.; Miller, L.; Jordan, J.

    2014-01-01

    Extranasal sites are common reservoirs of Staphylococcus aureus colonization, and may be relevant for methicillin-resistant S. aureus (MRSA) screening and infection control strategies. The objective here was to determine whether inguinal specimens could also be screened using Xpert SA Nasal Complete assay for MRSA. Results were compared to broth enrichment culture. Among 162 consented adults seeking care in the Emergency Department for cutaneous abscesses, inguinal specimens were found positive for MRSA more often than nares specimens; 24% and 26% by PCR or culture, respectively compared to 19% each by PCR or culture. Overall, 6% of adults colonized with MRSA would have been missed by nares screening alone. Compared to culture, Xpert SA Nasal Complete assay demonstrated sensitivity and specificity of 89% and 97%, respectively for detecting nares and/or inguinal MRSA colonization. In conclusion, inguinal specimens were a more common reservoir for MRSA than nares specimens in this population of patients. PMID:24958641

  19. Canadian National Breast Screening Study: 2. Breast cancer detection and death rates among women aged 50 to 59 years.

    PubMed Central

    Miller, A B; Baines, C J; To, T; Wall, C

    1992-01-01

    OBJECTIVE: To evaluate the efficacy of annual mammography over and above annual physical examination of the breasts and the teaching of breast self-examination among women aged 50 to 59 on entry. DESIGN: Individually randomized controlled trial. SETTING: Fifteen urban centres in Canada with expertise in the diagnosis and treatment of breast cancer. PARTICIPANTS: Women with no history of breast cancer and no mammography in the previous 12 months were randomly assigned to undergo either annual mammography and physical examination (MP group) or annual physical examination only (PO group). The 39,405 women enrolled from January 1980 through March 1985 were followed for a mean of 8.3 years. DATA COLLECTION: Derived from the participants by initial and annual self-administered questionnaires, from the screening examinations, from the patients' physicians, from the provincial cancer registries and by record linkage to the Canadian National Mortality Data Base. Expert panels evaluated histologic and death data. MAIN OUTCOME MEASURES: Rates of referral from screening, rates of detection of breast cancer from screening and from community care, nodal status, tumour size and rates of death from all causes and from breast cancer. RESULTS: Over 85% of the women in each group attended the screening sessions after screen 1. The characteristics of the women in the two groups were similar. Compared with the Canadian population the participants were more likely to be married, have fewer children, have more education, be in a professional occupation, smoke less and have been born in North America. The rate of screen-detected breast cancer on first examination was 7.20 per 1000 in the MP group and 3.45 per 1000 in the PO group, more node-positive tumours were found in the MP group than in the PO group. At subsequent screens the detection rates were a little less than half the rates at screen 1. During years 2 through 5 the ratios of observed to expected cases of invasive breast cancer

  20. Variation in Adenoma Detection Rate and the Lifetime Benefits and Cost of Colorectal Cancer Screening: A Microsimulation Model

    PubMed Central

    Meester, Reinier G.S.; Doubeni, Chyke A.; Lansdorp-Vogelaar, Iris; Jensen, Christopher D.; van der Meulen, Miriam P.; Levin, Theodore R.; Quinn, Virginia P.; Schottinger, Joanne E.; Zauber, Ann G.; Corley, Douglas A.; van Ballegooijen, Marjolein

    2015-01-01

    IMPORTANCE Colonoscopy is the most commonly used colorectal cancer screening test in the United States. Its quality, as measured by adenoma detection rates, varies widely between physicians with unknown consequences for the cost and benefits of screening programs. OBJECTIVE To estimate the lifetime benefits, complications and costs of a colonoscopy screening program at different levels of adenoma detection. DESIGN, SETTING and PARTICIPANTS This study used microsimulation modeling with data from a community-based healthcare system on adenoma detection rate variation and cancer risk among 136 physicians and 57,588 patients for 1998–2010. EXPOSURE Using modeling, no screening was compared to screening initiation with colonoscopy according to adenoma detection rate quintiles (averages 15.3, 21.3, 25.6, 30.9, and 38.7%) at ages 50, 60 and 70 with appropriate surveillance of adenoma patients. MAIN OUTCOMES Estimated lifetime colorectal cancer incidence, mortality, number of colonoscopies, complications and costs per 1,000 patients, all discounted at 3% per year and including 95% confidence intervals from multiway probabilistic sensitivity analysis (95%CI). RESULTS In simulation modeling, among unscreened patients, the lifetime risks of colorectal cancer incidence and mortality were 34.2 (95%CI:25.9–43.6) and 13.4 (95%CI:10.0–17.6) per 1,000, respectively. Among screened patients, simulated lifetime incidence decreased with lower to higher adenoma detection rates (quintile 1 versus 5: 26.6, 95%CI:20.0–34.3 versus 12.5, 95%CI:9.3–16.5) as did mortality (5.7, 95%CI:4.2–7.7 versus 2.3, 95%CI:1.7–3.1). Compared to quintile 1, simulated lifetime incidence and mortality were on average 11.4% (95%CI:10.3–11.9) and 12.8% (95%CI:11.1–13.7) lower, respectively, for every 5 percentage-point higher adenoma detection rate. Total colonoscopies and associated complications were higher from quintile 1 (2,777, 95%CI:2,626–2,943 and 6.0, 95%CI:4.0–8.5) to subsequent

  1. Identification of common cystic fibrosis mutations in African-Americans with cystic fibrosis increases the detection rate to 75%.

    PubMed Central

    Macek, M; Mackova, A; Hamosh, A; Hilman, B C; Selden, R F; Lucotte, G; Friedman, K J; Knowles, M R; Rosenstein, B J; Cutting, G R

    1997-01-01

    Cystic fibrosis (CF)--an autosomal recessive disorder caused by mutations in CF transmembrane conductance regulator (CFTR) and characterized by abnormal chloride conduction across epithelial membranes, leading to chronic lung and exocrine pancreatic disease--is less common in African-Americans than in Caucasians. No large-scale studies of mutation identification and screening in African-American CF patients have been reported, to date. In this study, the entire coding and flanking intronic sequence of the CFTR gene was analyzed by denaturing gradient-gel electrophoresis and sequencing in an index group of 82 African-American CF chromosomes to identify mutations. One novel mutation, 3120+1G-->A, occurred with a frequency of 12.3% and was also detected in a native African patient. To establish frequencies, an additional group of 66 African-American CF chromosomes were screened for mutations identified in two or more African-American patients. Screening for 16 "common Caucasian" mutations identified 52% of CF alleles in African-Americans, while screening for 8 "common African" mutations accounted for an additional 23%. The combined detection rate of 75% was comparable to the sensitivity of mutation analysis in Caucasian CF patients. These results indicate that African-Americans have their own set of "common" CF mutations that originate from the native African population. Inclusion of these "common" mutations substantially improves CF mutation detection rates in African-Americans. PMID:9150159

  2. An investigation towards real time dose rate monitoring, and fuel rod detection in a First Generation Magnox Storage Pond (FGMSP).

    PubMed

    Jackson, Sarah F; Monk, Stephen D; Riaz, Zahid

    2014-12-01

    The First Generation Magnox Storage Pond (FGMSP) is located on the Sellafield Nuclear Site, housing legacy spent Magnox nuclear fuel. Some of which has since corroded, forming a layer of Corroded Magnox Sludge (CMS) creating one of the largest decommissioning challenges the UK has faced. In this work the composition, physical properties and potentially high hazard nature of CMS are discussed, as are the gamma emission spectra of spent Magnox fuel rods typical of the ilk stored. We assess the potential use of a RadLine gamma detector to dose rate map this area and provide fuel rod detection. RadLine consists of a small scintillator, fibre optic cable and photon counter. The probe has the unusual advantage of not being electrically active and therefore fully submersible underwater, with the option to deploy hundreds of metres in length. Our experimental method encompasses general purpose Monte Carlo radiation transport code, MCNP, where we describe the modelling of CMS and pond liquor in comprehensive detail, including their radiological spectrum, chemical composition data, and physical properties. This investigation concludes that the maximum energy deposited within the scintillator crystal due to ambient CMS corresponds to a dose rate of 5.65Gy h(-1), thus above this value positive detection of a fuel rod would be anticipated. It is additionally established that the detectable region is within a 20cm range.

  3. An investigation towards real time dose rate monitoring, and fuel rod detection in a First Generation Magnox Storage Pond (FGMSP).

    PubMed

    Jackson, Sarah F; Monk, Stephen D; Riaz, Zahid

    2014-12-01

    The First Generation Magnox Storage Pond (FGMSP) is located on the Sellafield Nuclear Site, housing legacy spent Magnox nuclear fuel. Some of which has since corroded, forming a layer of Corroded Magnox Sludge (CMS) creating one of the largest decommissioning challenges the UK has faced. In this work the composition, physical properties and potentially high hazard nature of CMS are discussed, as are the gamma emission spectra of spent Magnox fuel rods typical of the ilk stored. We assess the potential use of a RadLine gamma detector to dose rate map this area and provide fuel rod detection. RadLine consists of a small scintillator, fibre optic cable and photon counter. The probe has the unusual advantage of not being electrically active and therefore fully submersible underwater, with the option to deploy hundreds of metres in length. Our experimental method encompasses general purpose Monte Carlo radiation transport code, MCNP, where we describe the modelling of CMS and pond liquor in comprehensive detail, including their radiological spectrum, chemical composition data, and physical properties. This investigation concludes that the maximum energy deposited within the scintillator crystal due to ambient CMS corresponds to a dose rate of 5.65Gy h(-1), thus above this value positive detection of a fuel rod would be anticipated. It is additionally established that the detectable region is within a 20cm range. PMID:25244071

  4. Comparison of two self-rating scales to detect depression: HADS and PHQ-9

    PubMed Central

    Hansson, Maja; Chotai, Jayanti; Nordstöm, Annika; Bodlund, Owe

    2009-01-01

    Background More than half of patients with depression go undetected. Self-rating scales can be useful in screening for depression, and measuring severity and treatment outcome. Aim This study compares the Hospital Anxiety and Depression Scale (HADS) and the Patient Health Questionnaire (PHQ-9) with regard to their psychometric properties, and investigates their agreement at different cut-off scores. Method Swedish primary care patients and psychiatric outpatients (n = 737) who reported symptoms of depression completed the self-rating scales. Data were collected from 2006 to 2007. Analyses with respect to internal consistency, factor analysis, and agreement (Cohen's κ) at recommended cut-offs were performed. Results Both scales had high internal consistency (α = 0.9) and stable factor structures. Using severity cut-offs, the PHQ-9 (≥5) diagnosed about 30% more patients than the HADS depression subscale (HADS-D; ≥8). They recognised the same prevalence of mild and moderate depression, but differed in relation to severe depression. When comparing recommended screening cut-offs, HADS-D ≥11 (33.5% of participants) and PHQ-9 ≥10 (65.9%) agreement was low (κ = 0.35). Using the lower recommended cut-off in the HADS-D (≥8), agreement with PHQ-9 ≥10 was moderate (κ = 0.52). The highest agreement (κ = 0.56) was found comparing HADS-D ≥8 with PHQ-9 ≥12. This also equalised the prevalence of depression found by the scales. Conclusion The HADS and PHQ-9 are both quick and reliable. The HADS has the advantage of evaluating both depression and anxiety, and the PHQ-9 of being strictly based upon the Diagnostic and Statistical Manual of Mental Disorders. The agreement between the scales at the best suitable cut-off is moderate, although the identified prevalence was similar. This indicates that the scales do not fully identify the same cases. This difference needs to be further explored. PMID:19761655

  5. Evidence for the effectiveness of a chlamydia awareness campaign: increased population rates of chlamydia testing and detection.

    PubMed

    Chen, Marcus Y; Karvelas, Maria; Sundararajan, Vijaya; Hocking, Jane S; Fairley, Christopher K

    2007-04-01

    The objective of this study was to determine the effectiveness of a statewide campaign aimed at increasing chlamydia awareness and testing among younger people. In November 2002, a narrowcast media campaign targeting men and women aged 16-29 years was launched in Victoria, Australia. This was expanded in June 2003. Data on chlamydia testing via Medicare and chlamydia notifications, before and after the campaign, were compared to determine possible effects of the campaign on population rates of chlamydia testing and detection. During the campaign, chlamydia testing rates increased significantly for both women (P=0.04) and men (P=0.04), while testing rates before and after the campaign remained relatively stable. Although testing rates increased, only 4.3% of Victorian women and 1.9% of men aged 16-30 were tested through Medicare in 2003. The increase in chlamydia testing over the study period was closely paralleled by an increase in notification rates for chlamydia, with strong correlations between the two (r=0.97, P<0.001). In conclusion, an estimated minimum of A$70 was spent on the campaign for each additional chlamydia test performed. Testing within the framework of a national chlamydia screening programme may be a more cost-effective way of increasing chlamydia testing. PMID:17509173

  6. Real-time detection of respiration rate with non-contact mode based on low-end imaging equipment

    NASA Astrophysics Data System (ADS)

    Jin, Xiaoli; Dong, Liquan; Zhao, Yuejin; Liu, Xiaohua; Liu, Ming; Yang, Lei; Liu, Weiyu; Zhao, Jingsheng; Xing, Jinhui

    2013-09-01

    Standard instrumentation for the assessment of respiration rate is large and based on invasive method, and not suitable for daily inspection. An optical, simple and non-contact measurement method to detect human respiration rate using lowend imaging equipment is discussed. This technology is based on the visible light absorption of blood, which contains many important physiological information of the cardiovascular system. The light absorption of facial area can be indirectly reflected to gray value of the corresponding area image. In this paper, we acquire the respiration rate through the video signal captured by low-end imaging equipment. Firstly, the color CCD captures the facial area below the eyes and every frame of the video can be separated into three RGB channels. The blue channel is extracted as the research object. Then, we calculate the mean gray value for each image and draw the mean gray curve along the time. Fourier transform can get the frequency spectrogram of the graph, which is filtered through the Fourier filter. The extreme point is the value of the respiratory rate. Finally, an available interface program is designed and we have some volunteers tested. The correlation coefficient between the experimental data and the data provided by a reference instrument is 0.98. The consistency of the experimental results is very well. This technology costs so low that it will be widely used in medical and daily respiration rate measurement.

  7. Impact of migration on new case detection rates in leprosy in Gudiyatham Taluk, Tamil Nadu, India.

    PubMed

    Samuel, P; Bushanam, J D R S; Ebenezer, M; Richard, J

    2012-01-01

    Migration of persons affected by leprosy was hinted at as early as 1929 (Bhaskara Rao 1930). All new cases of leprosy in Isfahan Province (Iran) were found to be migrants (Asilian et al 2005). Chudasama (2007) suspected increase in leprosy cases in Surat district to migration. These suggest migration contributes to new cases. This study was done to find out 1. Extent of migration among new cases, 2. Characteristics of migrants, 3. Occupational pattern 4.Reasons for migration. 5. Place of origin of migrants 6. Assimilation of migrants into the society. Trained staff collected information regarding migration using special questionnaire from all 222 new untreated cases from the field area of Community Health department during 2004 to 2008. Migrants were 10.4%. Distribution of place of residence, age, gender, marital status, education, mode of detection, Ridley-Jopling and MB/PB classifications of migrants were not significantly different from that of nonmigrants. Grade 2 deformities were more among migrants. All migrants found occupation. Mostly men migrated for job and women for joining their husbands. The role of migration in increasing the number of new cases cannot be minimized. Enhanced efforts should be made to provide adequate medical, health and rehabilitation services for them also. PMID:23720895

  8. Incorporating an Exercise Detection, Grading, and Hormone Dosing Algorithm Into the Artificial Pancreas Using Accelerometry and Heart Rate

    PubMed Central

    Jacobs, Peter G.; Resalat, Navid; El Youssef, Joseph; Reddy, Ravi; Branigan, Deborah; Preiser, Nicholas; Condon, John; Castle, Jessica

    2015-01-01

    In this article, we present several important contributions necessary for enabling an artificial endocrine pancreas (AP) system to better respond to exercise events. First, we show how exercise can be automatically detected using body-worn accelerometer and heart rate sensors. During a 22 hour overnight inpatient study, 13 subjects with type 1 diabetes wearing a Zephyr accelerometer and heart rate monitor underwent 45 minutes of mild aerobic treadmill exercise while controlling their glucose levels using sensor-augmented pump therapy. We used the accelerometer and heart rate as inputs into a validated regression model. Using this model, we were able to detect the exercise event with a sensitivity of 97.2% and a specificity of 99.5%. Second, from this same study, we show how patients’ glucose declined during the exercise event and we present results from in silico modeling that demonstrate how including an exercise model in the glucoregulatory model improves the estimation of the drop in glucose during exercise. Last, we present an exercise dosing adjustment algorithm and describe parameter tuning and performance using an in silico glucoregulatory model during an exercise event. PMID:26438720

  9. Using the Autism Detection in Early Childhood (ADEC) and Childhood Autism Rating Scales (CARS) to Predict Long Term Outcomes in Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Nah, Yong-Hwee; Young, Robyn L.; Brewer, Neil

    2014-01-01

    This study evaluated the predictive validity of the Autism Detection in Early Childhood (ADEC; Young, Autism detection in early childhood: ADEC. Australian Council of Educational Research, Camberwell, VIC 2007) and a well-established screening tool, the Childhood Autism Rating Scale (CARS; Schopler et al. The childhood autism rating scale (CARS).…

  10. Acute Radiation Effects on Cardiac Function Detected by Strain Rate Imaging in Breast Cancer Patients

    SciTech Connect

    Erven, Katrien; Jurcut, Ruxandra; Weltens, Caroline; Giusca, Sorin; Ector, Joris; Wildiers, Hans; Van den Bogaert, Walter; Voigt, Jens-Uwe

    2011-04-01

    Purpose: To investigate the occurrence of early radiation-induced changes in regional cardiac function using strain rate imaging (SRI) by tissue Doppler echocardiography. Methods and Materials: We included 20 left-sided and 10 right-sided breast cancer patients receiving radiotherapy (RT) to the breast or chest wall. Standard echocardiography and SRI were performed before RT (baseline), immediately after RT (post-RT), and at 2 months follow-up (FUP) after RT. Regional strain (S) and strain rate (SR) values were obtained from all 18 left ventricular (LV) segments. Data were compared to the regional radiation dose. Results: A reduction in S was observed post-RT and at FUP in left-sided patients (S{sub post-RT}: -17.6 {+-} 1.5%, and S{sub FUP}: -17.4 {+-} 2.3%, vs. S{sub baseline}: -19.5 {+-} 2.1%, p < 0.001) but not in right-sided patients. Within the left-sided patient group, S and SR were significantly reduced after RT in apical LV segments (S{sub post-RT}: -15.3 {+-} 2.5%, and S{sub FUP}: -14.3 {+-} 3.7%, vs. S{sub baseline}: -19.3 {+-} 3.0%, p < 0.01; and SR{sub post-RT}: -1.06 {+-} 0.15 s {sup -1}, and SR{sub FUP}: -1.16 {+-} 0.28 s {sup -1}, vs. SR{sub baseline}: -1.29 {+-} 0.27s {sup -1}, p = 0.01), but not in mid- or basal segments. Furthermore, we observed that segments exposed to more than 3 Gy showed a significant decrease in S after RT (S{sub post-RT}: -16.1 {+-} 1.6%, and S{sub FUP}: -15.8 {+-} 3.4%, vs. S{sub baseline}: -18.9 {+-} 2.6%, p < 0.001). This could not be observed in segments receiving less than 3 Gy. Conclusions: SRI shows a dose-related regional decrease in myocardial function after RT. It might be a useful tool in the evaluation of modern RT techniques, with respect to cardiac toxicity.

  11. High rates of detection of respiratory viruses in the nasal washes and mucosae of patients with chronic rhinosinusitis.

    PubMed

    Cho, Gye Song; Moon, Byung-Jae; Lee, Bong-Jae; Gong, Chang-Hoon; Kim, Nam Hee; Kim, You-Sun; Kim, Hun Sik; Jang, Yong Ju

    2013-03-01

    Respiratory viral infections are often implicated as triggers of chronic rhinosinusitis (CRS) flare-ups. However, there is a paucity of respiratory viral surveillance studies in CRS patients, and such studies could elucidate the potential role of viruses in promoting symptoms and aggravating mucosal inflammation. Therefore, a prospective case-control study was conducted to determine the prevalence of respiratory viruses in CRS patients and non-CRS controls. Nasal lavage fluids and turbinate epithelial cells were collected prospectively from 111 CRS patients and 50 controls. Multiplex PCR was used to identify common respiratory viruses in both sample types and the infection rate was compared between groups. Respiratory viruses were detected in 50.5% of lavage samples and in 64.0% of scraping samples from CRS patients. The overall infection rate was significantly different in CRS patients and controls (odds ratio, 2.9 in lavage and 4.1 in scraping samples). Multiple viral infections were detected more frequently in lavage samples from CRS patients than those from controls (P < 0.01; odds ratio, 7.7). Rhinovirus was the most prevalent virus and the only virus with a significantly different infection rate in CRS patients and controls in both samples (odds ratio, 3.2 in lavage and 3.4 in scraping samples). This study detected a higher prevalence of respiratory viruses in CRS patients than controls, suggesting that there may be significant associations between inflammation of CRS and respiratory viruses, particularly rhinovirus. Further studies should investigate the exact role of highly prevalent respiratory viruses in CRS patients during symptomatic aggravation and ongoing mucosal inflammation.

  12. Maximizing allele detection: Effects of analytical threshold and DNA levels on rates of allele and locus drop-out.

    PubMed

    Rakay, Christine A; Bregu, Joli; Grgicak, Catherine M

    2012-12-01

    Interpretation of DNA evidence depends upon the ability of the analyst to accurately compare the DNA profile obtained from an item of evidence and the DNA profile of a standard. This interpretation becomes progressively more difficult as the number of 'drop-out' and 'drop-in' events increase. Analytical thresholds (AT) are typically selected to ensure the false detection of noise is minimized. However, there exists a tradeoff between the erroneous labeling of noise as alleles and the false non-detection of alleles (i.e. drop-out). In this study, the effect ATs had on both types of error was characterized. Various ATs were tested, where three relied upon the analysis of baseline signals obtained from 31 negative samples. The fourth AT was determined by utilizing the relationship between RFU signal and DNA input. The other ATs were the commonly employed 50, 150 and 200 RFU thresholds. Receiver Operating Characteristic (ROC) plots showed that although high ATs completely negated the false labeling of noise, DNA analyzed with ATs derived using analysis of the baseline signal exhibited the lowest rates of drop-out and the lowest total error rates. In another experiment, the effect small changes in ATs had on drop-out was examined. This study showed that as the AT increased from ∼10 to 60 RFU, the number of heterozygous loci exhibiting the loss of one allele increased. Between ATs of 60 and 150 RFU, the frequency of allelic drop-out remained constant at 0.27 (±0.02) and began to decrease when ATs of 150 RFU or greater were utilized. In contrast, the frequency of heterozygous loci exhibiting the loss of both alleles consistently increased with AT. In summary, for samples amplified with less than 0.5ng of DNA, ATs derived from baseline analysis of negatives were shown to decrease the frequency of drop-out by a factor of 100 without significantly increasing rates of erroneous noise detection.

  13. Detection rate of diarrhoea-causing Kudoa hexapunctata in Pacific bluefin tuna Thunnus orientalis from Japanese waters.

    PubMed

    Suzuki, Jun; Murata, Rie; Yokoyama, Hiroshi; Sadamasu, Kenji; Kai, Akemi

    2015-02-01

    Diffuse outbreaks of food poisoning with unknown aetiologies leading to diarrhoea and vomiting within a short time after ingesting flatfish (Paralichthys olivaceus), tuna (Thunnus spp.), or amberjack (Seriola dumerili) have occurred nationwide in Japan, including the Tokyo metropolitan area. In this study, we surveyed the detection rates of kudoid parasites in 12 tuna samples that caused clinical diarrhoea from 2009 to 2012; we assessed 104 samples of whole juvenile Pacific bluefin tuna (PBT, Thunnus orientalis) and 153 block samples of other tuna distributed in the Tokyo Metropolitan Central Wholesale Market. The survey revealed that more than 70% of clinical diarrhoea cases due to tuna ingestion occurred between June and September, and Kudoa hexapunctata were detected in 9 of 12 tuna samples associated with clinical diarrhoea cases. The numbers of spores and 18S ribosomal DNA (rDNA) copies per gram of fish in 8 of 9 samples were more than 1×10(6) spores and 1×10(9) copies, respectively. Market research revealed that the K. hexapunctata-positive rate in juvenile PBT from Japanese waters was 64.4% (67/104) but that in adult PBT was 10.4% (7/67). The numbers of K. hexapunctata 18S rDNA copies in 64.5% (20/31) samples and 72.7% (16/22) of <5kg fish samples collected between May and July were more than 1×10(9)copies/g. On the other hand, kudoid parasites were not detected from 73 tuna samples except for a single sample of Thunnus albacares. Cell monolayer permeability assays performed to examine the toxicity of K. hexapunctata against Caco-2 cells revealed that the transepithelial electrical resistance (TER) in 5×10(7)K. hexapunctata spores decreased by 80% within 2-4h. In conclusion, K. hexapunctata was commonly detected in juvenile PBT from Japanese waters and are a likely cause of the diarrhoea outbreaks.

  14. Detection rate of diarrhoea-causing Kudoa hexapunctata in Pacific bluefin tuna Thunnus orientalis from Japanese waters.

    PubMed

    Suzuki, Jun; Murata, Rie; Yokoyama, Hiroshi; Sadamasu, Kenji; Kai, Akemi

    2015-02-01

    Diffuse outbreaks of food poisoning with unknown aetiologies leading to diarrhoea and vomiting within a short time after ingesting flatfish (Paralichthys olivaceus), tuna (Thunnus spp.), or amberjack (Seriola dumerili) have occurred nationwide in Japan, including the Tokyo metropolitan area. In this study, we surveyed the detection rates of kudoid parasites in 12 tuna samples that caused clinical diarrhoea from 2009 to 2012; we assessed 104 samples of whole juvenile Pacific bluefin tuna (PBT, Thunnus orientalis) and 153 block samples of other tuna distributed in the Tokyo Metropolitan Central Wholesale Market. The survey revealed that more than 70% of clinical diarrhoea cases due to tuna ingestion occurred between June and September, and Kudoa hexapunctata were detected in 9 of 12 tuna samples associated with clinical diarrhoea cases. The numbers of spores and 18S ribosomal DNA (rDNA) copies per gram of fish in 8 of 9 samples were more than 1×10(6) spores and 1×10(9) copies, respectively. Market research revealed that the K. hexapunctata-positive rate in juvenile PBT from Japanese waters was 64.4% (67/104) but that in adult PBT was 10.4% (7/67). The numbers of K. hexapunctata 18S rDNA copies in 64.5% (20/31) samples and 72.7% (16/22) of <5kg fish samples collected between May and July were more than 1×10(9)copies/g. On the other hand, kudoid parasites were not detected from 73 tuna samples except for a single sample of Thunnus albacares. Cell monolayer permeability assays performed to examine the toxicity of K. hexapunctata against Caco-2 cells revealed that the transepithelial electrical resistance (TER) in 5×10(7)K. hexapunctata spores decreased by 80% within 2-4h. In conclusion, K. hexapunctata was commonly detected in juvenile PBT from Japanese waters and are a likely cause of the diarrhoea outbreaks. PMID:25461601

  15. Detection and decay rates of prey and prey symbionts in the gut of a predator through metagenomics.

    PubMed

    Paula, Débora P; Linard, Benjamin; Andow, David A; Sujii, Edison R; Pires, Carmen S S; Vogler, Alfried P

    2015-07-01

    DNA methods are useful to identify ingested prey items from the gut of predators, but reliable detection is hampered by low amounts of degraded DNA. PCR-based methods can retrieve minute amounts of starting material but suffer from amplification biases and cross-reactions with the predator and related species genomes. Here, we use PCR-free direct shotgun sequencing of total DNA isolated from the gut of the harlequin ladybird Harmonia axyridis at five time points after feeding on a single pea aphid Acyrthosiphon pisum. Sequence reads were matched to three reference databases: Insecta mitogenomes of 587 species, including H. axyridis sequenced here; A. pisum nuclear genome scaffolds; and scaffolds and complete genomes of 13 potential bacterial symbionts. Immediately after feeding, multicopy mtDNA of A. pisum was detected in tens of reads, while hundreds of matches to nuclear scaffolds were detected. Aphid nuclear DNA and mtDNA decayed at similar rates (0.281 and 0.11 h(-1) respectively), and the detectability periods were 32.7 and 23.1 h. Metagenomic sequencing also revealed thousands of reads of the obligate Buchnera aphidicola and facultative Regiella insecticola aphid symbionts, which showed exponential decay rates significantly faster than aphid DNA (0.694 and 0.80 h(-1) , respectively). However, the facultative aphid symbionts Hamiltonella defensa, Arsenophonus spp. and Serratia symbiotica showed an unexpected temporary increase in population size by 1-2 orders of magnitude in the predator guts before declining. Metagenomics is a powerful tool that can reveal complex relationships and the dynamics of interactions among predators, prey and their symbionts. PMID:25545417

  16. Detection and decay rates of prey and prey symbionts in the gut of a predator through metagenomics.

    PubMed

    Paula, Débora P; Linard, Benjamin; Andow, David A; Sujii, Edison R; Pires, Carmen S S; Vogler, Alfried P

    2015-07-01

    DNA methods are useful to identify ingested prey items from the gut of predators, but reliable detection is hampered by low amounts of degraded DNA. PCR-based methods can retrieve minute amounts of starting material but suffer from amplification biases and cross-reactions with the predator and related species genomes. Here, we use PCR-free direct shotgun sequencing of total DNA isolated from the gut of the harlequin ladybird Harmonia axyridis at five time points after feeding on a single pea aphid Acyrthosiphon pisum. Sequence reads were matched to three reference databases: Insecta mitogenomes of 587 species, including H. axyridis sequenced here; A. pisum nuclear genome scaffolds; and scaffolds and complete genomes of 13 potential bacterial symbionts. Immediately after feeding, multicopy mtDNA of A. pisum was detected in tens of reads, while hundreds of matches to nuclear scaffolds were detected. Aphid nuclear DNA and mtDNA decayed at similar rates (0.281 and 0.11 h(-1) respectively), and the detectability periods were 32.7 and 23.1 h. Metagenomic sequencing also revealed thousands of reads of the obligate Buchnera aphidicola and facultative Regiella insecticola aphid symbionts, which showed exponential decay rates significantly faster than aphid DNA (0.694 and 0.80 h(-1) , respectively). However, the facultative aphid symbionts Hamiltonella defensa, Arsenophonus spp. and Serratia symbiotica showed an unexpected temporary increase in population size by 1-2 orders of magnitude in the predator guts before declining. Metagenomics is a powerful tool that can reveal complex relationships and the dynamics of interactions among predators, prey and their symbionts.

  17. Transferred subgroup false discovery rate for rare post-translational modifications detected by mass spectrometry.

    PubMed

    Fu, Yan; Qian, Xiaohong

    2014-05-01

    In shotgun proteomics, high-throughput mass spectrometry experiments and the subsequent data analysis produce thousands to millions of hypothetical peptide identifications. The common way to estimate the false discovery rate (FDR) of peptide identifications is the target-decoy database search strategy, which is efficient and accurate for large datasets. However, the legitimacy of the target-decoy strategy for protein-modification-centric studies has rarely been rigorously validated. It is often the case that a global FDR is estimated for all peptide identifications including both modified and unmodified peptides, but that only a subgroup of identifications with a certain type of modification is focused on. As revealed recently, the subgroup FDR of modified peptide identifications can differ dramatically from the global FDR at the same score threshold, and thus the former, when it is of interest, should be separately estimated. However, rare modifications often result in a very small number of modified peptide identifications, which makes the direct separate FDR estimation inaccurate because of the inadequate sample size. This paper presents a method called the transferred FDR for accurately estimating the FDR of an arbitrary number of modified peptide identifications. Through flexible use of the empirical data from a target-decoy database search, a theoretical relationship between the subgroup FDR and the global FDR is made computable. Through this relationship, the subgroup FDR can be predicted from the global FDR, allowing one to avoid an inaccurate direct estimation from a limited amount of data. The effectiveness of the method is demonstrated with both simulated and real mass spectra.

  18. A Real-Time Atrial Fibrillation Detection Algorithm Based on the Instantaneous State of Heart Rate.

    PubMed

    Zhou, Xiaolin; Ding, Hongxia; Wu, Wanqing; Zhang, Yuanting

    2015-01-01

    Atrial fibrillation (AF), the most frequent cause of cardioembolic stroke, is increasing in prevalence as the population ages, and presents with a broad spectrum of symptoms and severity. The early identification of AF is an essential part for preventing the possibility of blood clotting and stroke. In this work, a real-time algorithm is proposed for accurately screening AF episodes in electrocardiograms. This method adopts heart rate sequence, and it involves the application of symbolic dynamics and Shannon entropy. Using novel recursive algorithms, a low-computational complexity can be obtained. Four publicly-accessible sets of clinical data (Long-Term AF, MIT-BIH AF, MIT-BIH Arrhythmia, and MIT-BIH Normal Sinus Rhythm Databases) were used for assessment. The first database was selected as a training set; the receiver operating characteristic (ROC) curve was performed, and the best performance was achieved at the threshold of 0.639: the sensitivity (Se), specificity (Sp), positive predictive value (PPV) and overall accuracy (ACC) were 96.14%, 95.73%, 97.03% and 95.97%, respectively. The other three databases were used for independent testing. Using the obtained decision-making threshold (i.e., 0.639), for the second set, the obtained parameters were 97.37%, 98.44%, 97.89% and 97.99%, respectively; for the third database, these parameters were 97.83%, 87.41%, 47.67% and 88.51%, respectively; the Sp was 99.68% for the fourth set. The latest methods were also employed for comparison. Collectively, results presented in this study indicate that the combination of symbolic dynamics and Shannon entropy yields a potent AF detector, and suggest this method could be of practical use in both clinical and out-of-clinical settings. PMID:26376341

  19. Detection, mapping and estimation of rate of spread of grass fires from southern African ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Wightman, J. M.

    1973-01-01

    Sequential band-6 imagery of the Zambesi Basin of southern Africa recorded substantial changes in burn patterns resulting from late dry season grass fires. One example from northern Botswana, indicates that a fire consumed approximately 70 square miles of grassland over a 24-hour period. Another example from western Zambia indicates increased fire activity over a 19-day period. Other examples clearly define the area of widespread grass fires in Angola, Botswana, Rhodesia and Zambia. From the fire patterns visible on the sequential portions of the imagery, and the time intervals involved, the rates of spread of the fires are estimated and compared with estimates derived from experimental burning plots in Zambia and Canada. It is concluded that sequential ERTS-1 imagery, of the quality studied, clearly provides the information needed to detect and map grass fires and to monitor their rates of spread in this region during the late dry season.

  20. Why HOC+ is detectable in interstellar clouds: the rate of the reaction between HOC+ and H2

    PubMed

    Herbst, E; Woon, D E

    1996-06-01

    The recent confirmation by Ziurys and Apponi of the detection of HOC+ toward Sgr B2 (OH), and their identification of the ion in Orion-KL and several other sources show that HOC+ is far more abundant than predicted by previous ion-molecule models. In these models, the reaction HOC(+) + H2 --> HCO(+) + H2 is assumed to rapidly destroy HOC+, based on the results of a prior calculation. We have recalculated the rate of this reaction as a function of temperature using a new ab initio potential surface and a phase space approach to the dynamics which includes tunneling. The newly calculated rate is small (< or = 1 x 10(-10) cm3 s-1) at temperatures under 100 K.

  1. Why HOC+ is detectable in interstellar clouds: the rate of the reaction between HOC+ and H2

    NASA Technical Reports Server (NTRS)

    Herbst, E.; Woon, D. E.

    1996-01-01

    The recent confirmation by Ziurys and Apponi of the detection of HOC+ toward Sgr B2 (OH), and their identification of the ion in Orion-KL and several other sources show that HOC+ is far more abundant than predicted by previous ion-molecule models. In these models, the reaction HOC(+) + H2 --> HCO(+) + H2 is assumed to rapidly destroy HOC+, based on the results of a prior calculation. We have recalculated the rate of this reaction as a function of temperature using a new ab initio potential surface and a phase space approach to the dynamics which includes tunneling. The newly calculated rate is small (< or = 1 x 10(-10) cm3 s-1) at temperatures under 100 K.

  2. Canadian National Breast Screening Study: 1. Breast cancer detection and death rates among women aged 40 to 49 years.

    PubMed Central

    Miller, A B; Baines, C J; To, T; Wall, C

    1992-01-01

    OBJECTIVES: To evaluate the efficacy of the combination of annual screening with mammography, physical examination of the breasts and the teaching of breast self-examination in reducing the rate of death from breast cancer among women aged 40 to 49 years on entry. DESIGN: Individually randomized controlled trial. SETTING: Fifteen urban centres in Canada with expertise in the diagnosis and treatment of breast cancer. PARTICIPANTS: Women with no history of breast cancer and no mammography in the previous 12 months were randomly assigned to undergo either annual mammography and physical examination (MP group) or usual care after an initial physical examination (UC group). The 50,430 women enrolled from January 1980 through March 1985 were followed for a mean of 8.5 years. DATA COLLECTION: Derived from the participants by initial and annual self-administered questionnaires, from the screening examinations, from the patients' physicians, from the provincial cancer registries and by record linkage to the Canadian National Mortality Data Base. Expert panels evaluated histologic and death data. MAIN OUTCOME MEASURES: Rates of referral from screening, rates of detection of breast cancer from screening and from community care, nodal status, tumour size, and rates of death from all causes and from breast cancer. RESULTS: Over 90% of the women in each group attended the screening sessions or returned the annual questionnaires, or both, over years 2 to 5. The characteristics of the women in the two groups were similar. Compared with the Canadian population, the participants were more likely to be married, have fewer children, have more education, be in a professional occupation, smoke less and have been born in North America. The rate of screen-detected breast cancer on first examination was 3.89 per 1000 in the MP group and 2.46 per 1000 in the UC group; more node-positive tumours were found in the MP group than in the UC group. During years 2 through 5 the ratios of observed

  3. Analysis of variables affecting unemployment rate and detecting for cluster in West Java, Central Java, and East Java in 2012

    NASA Astrophysics Data System (ADS)

    Samuel, Putra A.; Widyaningsih, Yekti; Lestari, Dian

    2016-02-01

    The objective of this study is modeling the Unemployment Rate (UR) in West Java, Central Java, and East Java, with rate of disease, infant mortality rate, educational level, population size, proportion of married people, and GDRP as the explanatory variables. Spatial factors are also considered in the modeling since the closer the distance, the higher the correlation. This study uses the secondary data from BPS (Badan Pusat Statistik). The data will be analyzed using Moran I test, to obtain the information about spatial dependence, and using Spatial Autoregressive modeling to obtain the information, which variables are significant affecting UR and how great the influence of the spatial factors. The result is, variables proportion of married people, rate of disease, and population size are related significantly to UR. In all three regions, the Hotspot of unemployed will also be detected districts/cities using Spatial Scan Statistics Method. The results are 22 districts/cities as a regional group with the highest unemployed (Most likely cluster) in the study area; 2 districts/cities as a regional group with the highest unemployed in West Java; 1 district/city as a regional groups with the highest unemployed in Central Java; 15 districts/cities as a regional group with the highest unemployed in East Java.

  4. Prospective assessment of the false positive rate of the Australian snake venom detection kit in healthy human samples.

    PubMed

    Nimorakiotakis, Vasilios Bill; Winkel, Kenneth D

    2016-03-01

    The Snake Venom Detection Kit (SVDK; bioCSL Pty Ltd, Australia) distinguishes venom from the five most medically significant snake immunotypes found in Australia. This study assesses the rate of false positives that, by definition, refers to a positive assay finding in a sample from someone who has not been bitten by a venomous snake. Control unbroken skin swabs, simulated bite swabs and urine specimens were collected from 61 healthy adult volunteers [33 males and 28 females] for assessment. In all controls, simulated bite site and urine samples [a total of 183 tests], the positive control well reacted strongly within one minute and no test wells reacted during the ten minute incubation period. However, in two urine tests, the negative control well gave a positive reaction (indicating an uninterpretable test). A 95% confidence interval for the false positive rate, on a per-patient rate, derived from the findings of this study, would extend from 0% to 6% and, on a per-test basis, it would be 0-2%. It appears to be a very low incidence (0-6%) of intrinsic true false positives for the SVDK. The clinical impresssion of a high SVDK false positive rate may be mostly related to operator error.

  5. Detectability of contrast agents for video-rate confocal reflectance microscopy of skin and microcirculation in vivo

    NASA Astrophysics Data System (ADS)

    Rajadhyaksha, Milind M.; Gonzalez, Salvador

    2003-06-01

    The lack of structure-specific contrast limits the usefulness of confocal reflectance microscopy to morphologic investigations at the cellular- and nuclear-level in human and animal skin in vivo. Morphologic and functional imaging at specific organelle- and ultrastructure-levels will require contrast agents that may be used and detected in vivo. High-resolution confocal reflectance imaging is based on the detection of singly back-scattered photons, where contrast is provided by variations in the refractive indices of microstructures. We carried out a quantitative Mie back-scatter analysis and imaging experiments to understand signal detectability of reflectance contrast agents for visualizing human skin and animal microcirculation. When imaging at video-rate with illumination of 10 milliwatts at 1064 nm, we detect 100-104 photons/pixel from the epidermis to dermis, relative to a background of 100 photons; this provides a signal-to-noise ratio of 3-40 and signal-to-background of 1-100. Organelles of size (d) 0.1-1.0 μm with refractive indices (n) of 1.34-1.45 (relative to n=1.34 for epidermis, n=1.38 for dermis) back-scatter 10-104 photons/pixel. Exogenous contrast agents such as liposomes (n=1.41, d=0.7 μm) and polystyrene microspheres (d=0.2-1.0 μm, n=1.57; 100-105 photons/pixel) are detectable and they strongly enhance the contrast of microcirculation in the dermis of Sprague-Dawley rats. Topically applied 5% acetic acid causes the intra-nuclear 30-100 nm-thin chromatin filaments to condense into 1-5 μm-thick strands, increasing back-scattered signal from 100 to 104 photons/pixels, making the nuclei appear bright and easily detectable in basal cell cancers. Such analyses provide a basis for optimizing confocal microscope design for detectability of contrast agents in vivo.

  6. A Control Allocation System for Automatic Detection and Compensation of Phase Shift Due to Actuator Rate Limiting

    NASA Technical Reports Server (NTRS)

    Yildiz, Yidiray; Kolmanovsky, Ilya V.; Acosta, Diana

    2011-01-01

    This paper proposes a control allocation system that can detect and compensate the phase shift between the desired and the actual total control effort due to rate limiting of the actuators. Phase shifting is an important problem in control system applications since it effectively introduces a time delay which may destabilize the closed loop dynamics. A relevant example comes from flight control where aggressive pilot commands, high gain of the flight control system or some anomaly in the system may cause actuator rate limiting and effective time delay introduction. This time delay can instigate Pilot Induced Oscillations (PIO), which is an abnormal coupling between the pilot and the aircraft resulting in unintentional and undesired oscillations. The proposed control allocation system reduces the effective time delay by first detecting the phase shift and then minimizing it using constrained optimization techniques. Flight control simulation results for an unstable aircraft with inertial cross coupling are reported, which demonstrate phase shift minimization and recovery from a PIO event.

  7. Re-entry communication through a plasma sheath using standing wave detection and adaptive data rate control

    NASA Astrophysics Data System (ADS)

    Xie, Kai; Yang, Min; Bai, Bowen; Li, Xiaoping; Zhou, Hui; Guo, Lixin

    2016-01-01

    Radio blackout during the re-entry has puzzled the aerospace industry for decades and has not yet been completely resolved. To achieve a continuous data link in the spacecraft's re-entry period, a simple and practicable communication method is proposed on the basis that (1) the electromagnetic-wave backscatter of the plasma sheath affects the voltage standing wave ratio (VSWR) of the antenna, and the backscatter is negatively correlated to transmission components, and (2) the transmission attenuation caused by the plasma sheath reduces the channel capacity. We detect the voltage standing wave ratio changes of the antenna and then adjust the information rate to accommodate the varying channel capacity, thus guaranteeing continuous transmission (for fewer critical data). The experiment was carried out in a plasma generator with an 18-cm-thick and 30-cm-diameter hollow propagation path, and the adaptive communication was implemented using spread spectrum frequency, shift key modulation with a variable spreading factor. The experimental results indicate that, when the over-threshold of VSWR was detected, the bit rate reduced to 250 bps from 4 Mbps automatically and the tolerated plasma density increased by an order of magnitude, which validates the proposed scheme. The proposed method has little additional cost, and the adaptive control does not require a feedback channel. The method is therefore applicable to data transmission in a single direction, such as that of a one-way telemetry system.

  8. Time-resolved in vivo luminescence dosimetry for online error detection in pulsed dose-rate brachytherapy

    SciTech Connect

    Andersen, Claus E.; Nielsen, Soeren Kynde; Lindegaard, Jacob Christian; Tanderup, Kari

    2009-11-15

    Purpose: The purpose of this study is to present and evaluate a dose-verification protocol for pulsed dose-rate (PDR) brachytherapy based on in vivo time-resolved (1 s time resolution) fiber-coupled luminescence dosimetry. Methods: Five cervix cancer patients undergoing PDR brachytherapy (Varian GammaMed Plus with {sup 192}Ir) were monitored. The treatments comprised from 10 to 50 pulses (1 pulse/h) delivered by intracavitary/interstitial applicators (tandem-ring systems and/or needles). For each patient, one or two dosimetry probes were placed directly in or close to the tumor region using stainless steel or titanium needles. Each dosimeter probe consisted of a small aluminum oxide crystal attached to an optical fiber cable (1 mm outer diameter) that could guide radioluminescence (RL) and optically stimulated luminescence (OSL) from the crystal to special readout instrumentation. Positioning uncertainty and hypothetical dose-delivery errors (interchanged guide tubes or applicator movements from {+-}5 to {+-}15 mm) were simulated in software in order to assess the ability of the system to detect errors. Results: For three of the patients, the authors found no significant differences (P>0.01) for comparisons between in vivo measurements and calculated reference values at the level of dose per dwell position, dose per applicator, or total dose per pulse. The standard deviations of the dose per pulse were less than 3%, indicating a stable dose delivery and a highly stable geometry of applicators and dosimeter probes during the treatments. For the two other patients, the authors noted significant deviations for three individual pulses and for one dosimeter probe. These deviations could have been due to applicator movement during the treatment and one incorrectly positioned dosimeter probe, respectively. Computer simulations showed that the likelihood of detecting a pair of interchanged guide tubes increased by a factor of 10 or more for the considered patients when

  9. Monte Carlo simulations of the diurnal variation in seismic detection rate of sporadic meteoroid impacts on the moon

    NASA Technical Reports Server (NTRS)

    Oberst, J.; Nakamura, Y.

    1989-01-01

    The rate of detection of meteoroid impacts on the moon by the lunar seismic network shows a characteristic diurnal variation. Assuming that these meteoroids have a flux and a preimpact orbital distribution similar to that of fireballs observed by terrestrial camera networks, one can compute the expected diurnal variation for a given set of parameters that describe the seismic wave generation and transmission on the moon. An iterative process to match the theoretical variation with the observed one has led us to the following results: (1) the majority of the detected impact events occur within a closer range of the network than was believed earlier. This results in higher meteoroid flux estimates from lunar seismic data that agree with the terrestrially measured flux. (2) For meteoroid masses smaller than 1000 g, seismic amplitude is approximately proportional to the one-fifth power of the impact speed; for larger masses it is approximately proportional to the eight-fifth power, provided that the terrestrial meteor data used for analysis are not biased. (3) Seismic efficiency of meteoroids smaller than 1000 g is significantly less than that of large meteoroids. (4) Using orbits of fireballs that represent meteorites, we predict that the share of meteorites among the detected impacts is approximately 15 percent assuming that seismic efficiency of the high-density meteorites is the same as that of average meteoroids. A greatly increased seismic efficiency for these high-density objects is not likely.

  10. Early Detection, Curative Treatment, and Survival Rates for Hepatocellular Carcinoma Surveillance in Patients with Cirrhosis: A Meta-analysis

    PubMed Central

    Singal, Amit G.; Pillai, Anjana; Tiro, Jasmin

    2014-01-01

    Background Surveillance for hepatocellular carcinoma (HCC) has level I evidence among patients with hepatitis B but only level II evidence in patients with cirrhosis. This lack of randomized data has spurred questions regarding the utility of HCC surveillance in this patient population; however, lack of randomized data does not equate to a lack of data supporting the efficacy of surveillance. The aim of our study was to determine the effect of HCC surveillance on early stage tumor detection, receipt of curative therapy, and overall survival in patients with cirrhosis. Methods and Findings We performed a systematic literature review using Medline from January 1990 through January 2014 and a search of national meeting abstracts from 2009–2012. Two investigators identified studies that reported rates of early stage tumor detection, curative treatment receipt, or survival, stratified by HCC surveillance status, among patients with cirrhosis. Both investigators independently extracted data on patient populations, study methods, and results using standardized forms. Pooled odds ratios, according to HCC surveillance status, were calculated for each outcome using the DerSimonian and Laird method for a random effects model. We identified 47 studies with 15,158 patients, of whom 6,284 (41.4%) had HCC detected by surveillance. HCC surveillance was associated with improved early stage detection (odds ratio [OR] 2.08, 95% CI 1.80–2.37) and curative treatment rates (OR 2.24, 95% CI 1.99–2.52). HCC surveillance was associated with significantly prolonged survival (OR 1.90, 95% CI 1.67–2.17), which remained significant in the subset of studies adjusting for lead-time bias. Limitations of current data included many studies having insufficient duration of follow-up to assess survival and the majority not adjusting for liver function or lead-time bias. Conclusions HCC surveillance is associated with significant improvements in early tumor detection, receipt of curative

  11. Heart rate variability parameters and fetal movement complement fetal behavioral states detection via magnetography to monitor neurovegetative development

    PubMed Central

    Brändle, Johanna; Preissl, Hubert; Draganova, Rossitza; Ortiz, Erick; Kagan, Karl O.; Abele, Harald; Brucker, Sara Y.; Kiefer-Schmidt, Isabelle

    2015-01-01

    Fetal behavioral states are defined by fetal movement and heart rate variability (HRV). At 32 weeks of gestational age (GA) the distinction of four fetal behavioral states represented by combinations of quiet or active sleep or awakeness is possible. Prior to 32 weeks, only periods of fetal activity and quiesence can be distinguished. The increasing synchronization of fetal movement and HRV reflects the development of the autonomic nervous system (ANS) control. Fetal magnetocardiography (fMCG) detects fetal heart activity at high temporal resolution, enabling the calculation of HRV parameters. This study combined the criteria of fetal movement with the HRV analysis to complete the criteria for fetal state detection. HRV parameters were calculated including the standard deviation of the normal-to-normal R–R interval (SDNN), the mean square of successive differences of the R–R intervals (RMSSD, SDNN/RMSSD ratio, and permutation entropy (PE) to gain information about the developing influence of the ANS within each fetal state. In this study, 55 magnetocardiograms from healthy fetuses of 24–41 weeks’ GA were recorded for up to 45 min using a fetal biomagnetometer. Fetal states were classified based on HRV and movement detection. HRV parameters were calculated for each state. Before GA 32 weeks, 58.4% quiescence and 41.6% activity cycles were observed. Later, 24% quiet sleep state (1F), 65.4% active sleep state (2F), and 10.6% active awake state (4F) were observed. SDNN increased over gestation. Changes of HRV parameters between the fetal behavioral states, especially between 1F and 4F, were statistically significant. Increasing fetal activity was confirmed by a decrease in PE complexity measures. The fHRV parameters support the differentiation between states and indicate the development of autonomous nervous control of heart rate function. PMID:25904855

  12. Detection of QTL for exudation rate at ripening stage in rice and its contribution to hydraulic conductance.

    PubMed

    Yamamoto, Toshio; Suzuki, Tadafumi; Suzuki, Kenji; Adachi, Shunsuke; Sun, Jian; Yano, Masahiro; Ookawa, Taiichiro; Hirasawa, Tadashi

    2016-01-01

    Dry matter production of crops is determined by how much light they intercept and how efficiently they use it for carbon fixation; i.e., photosynthesis. The high-yielding rice cultivar, Akenohoshi, maintains a high photosynthetic rate in the middle of the day owing to its high hydraulic conductance in comparison with the elite commercial rice cultivar, Koshihikari. We developed 94 recombinant inbred lines derived from Akenohoshi and Koshihikari and measured their exudation rate to calculate hydraulic conductance to osmotic water transport in a paddy field. A quantitative trait locus (QTL) for exudation rate was detected on the long arm of chromosome 2 at the heading and ripening stages. We developed chromosome segment substitution lines which carried Akenohoshi segments in the Koshihikari genetic background, and measured hydraulic conductance to both osmotic and passive water transport. The QTL was confirmed to be located within a region of about 4.2Mbp on the distal end of long arm of chromosome 2. The Akenohoshi allele increased root surface area and hydraulic conductance, but didn't increase hydraulic conductivity of a plant.

  13. Detection of QTL for exudation rate at ripening stage in rice and its contribution to hydraulic conductance.

    PubMed

    Yamamoto, Toshio; Suzuki, Tadafumi; Suzuki, Kenji; Adachi, Shunsuke; Sun, Jian; Yano, Masahiro; Ookawa, Taiichiro; Hirasawa, Tadashi

    2016-01-01

    Dry matter production of crops is determined by how much light they intercept and how efficiently they use it for carbon fixation; i.e., photosynthesis. The high-yielding rice cultivar, Akenohoshi, maintains a high photosynthetic rate in the middle of the day owing to its high hydraulic conductance in comparison with the elite commercial rice cultivar, Koshihikari. We developed 94 recombinant inbred lines derived from Akenohoshi and Koshihikari and measured their exudation rate to calculate hydraulic conductance to osmotic water transport in a paddy field. A quantitative trait locus (QTL) for exudation rate was detected on the long arm of chromosome 2 at the heading and ripening stages. We developed chromosome segment substitution lines which carried Akenohoshi segments in the Koshihikari genetic background, and measured hydraulic conductance to both osmotic and passive water transport. The QTL was confirmed to be located within a region of about 4.2Mbp on the distal end of long arm of chromosome 2. The Akenohoshi allele increased root surface area and hydraulic conductance, but didn't increase hydraulic conductivity of a plant. PMID:26566844

  14. NOTE: Detection limits for ferrimagnetic particle concentrations using magnetic resonance imaging based proton transverse relaxation rate measurements

    NASA Astrophysics Data System (ADS)

    Pardoe, H.; Chua-anusorn, W.; St. Pierre, T. G.; Dobson, J.

    2003-03-01

    A clinical magnetic resonance imaging (MRI) system was used to measure proton transverse relaxation rates (R2) in agar gels with varying concentrations of ferrimagnetic iron oxide nanoparticles in a field strength of 1.5 T. The nanoparticles were prepared by coprecipitation of ferric and ferrous ions in the presence of either dextran or polyvinyl alcohol. The method of preparation resulted in loosely packed clusters (dextran) or branched chains (polyvinyl alcohol) of particles containing of the order of 600 and 400 particles, respectively. For both methods of particle preparation, concentrations of ferrimagnetic iron in agar gel less than 0.01 mg ml-1 had no measurable effect on the value of R2 for the gel. The results indicate that MRI-based R2 measurements using 1.5 T clinical scanners are not quite sensitive enough to detect the very low concentrations of nanoparticulate biogenic magnetite reported in human brain tissue.

  15. A finite rate of innovation algorithm for fast and accurate spike detection from two-photon calcium imaging

    NASA Astrophysics Data System (ADS)

    Oñativia, Jon; Schultz, Simon R.; Dragotti, Pier Luigi

    2013-08-01

    Objective. Inferring the times of sequences of action potentials (APs) (spike trains) from neurophysiological data is a key problem in computational neuroscience. The detection of APs from two-photon imaging of calcium signals offers certain advantages over traditional electrophysiological approaches, as up to thousands of spatially and immunohistochemically defined neurons can be recorded simultaneously. However, due to noise, dye buffering and the limited sampling rates in common microscopy configurations, accurate detection of APs from calcium time series has proved to be a difficult problem. Approach. Here we introduce a novel approach to the problem making use of finite rate of innovation (FRI) theory (Vetterli et al 2002 IEEE Trans. Signal Process. 50 1417-28). For calcium transients well fit by a single exponential, the problem is reduced to reconstructing a stream of decaying exponentials. Signals made of a combination of exponentially decaying functions with different onset times are a subclass of FRI signals, for which much theory has recently been developed by the signal processing community. Main results. We demonstrate for the first time the use of FRI theory to retrieve the timing of APs from calcium transient time series. The final algorithm is fast, non-iterative and parallelizable. Spike inference can be performed in real-time for a population of neurons and does not require any training phase or learning to initialize parameters. Significance. The algorithm has been tested with both real data (obtained by simultaneous electrophysiology and multiphoton imaging of calcium signals in cerebellar Purkinje cell dendrites), and surrogate data, and outperforms several recently proposed methods for spike train inference from calcium imaging data.

  16. A finite rate of innovation algorithm for fast and accurate spike detection from two-photon calcium imaging

    PubMed Central

    Oñativia, Jon; Schultz, Simon R; Dragotti, Pier Luigi

    2014-01-01

    Objective Inferring the times of sequences of action potentials (APs) (spike trains) from neurophysiological data is a key problem in computational neuroscience. The detection of APs from two-photon imaging of calcium signals offers certain advantages over traditional electrophysiological approaches, as up to thousands of spatially and immunohistochemically defined neurons can be recorded simultaneously. However, due to noise, dye buffering and the limited sampling rates in common microscopy configurations, accurate detection of APs from calcium time series has proved to be a difficult problem. Approach Here we introduce a novel approach to the problem making use of finite rate of innovation (FRI) theory (Vetterli et al 2002 IEEE Trans. Signal Process. 50 1417–28). For calcium transients well fit by a single exponential, the problem is reduced to reconstructing a stream of decaying exponentials. Signals made of a combination of exponentially decaying functions with different onset times are a subclass of FRI signals, for which much theory has recently been developed by the signal processing community. Main results We demonstrate for the first time the use of FRI theory to retrieve the timing of APs from calcium transient time series. The final algorithm is fast, non-iterative and parallelizable. Spike inference can be performed in real-time for a population of neurons and does not require any training phase or learning to initialize parameters. Significance The algorithm has been tested with both real data (obtained by simultaneous electrophysiology and multiphoton imaging of calcium signals in cerebellar Purkinje cell dendrites), and surrogate data, and outperforms several recently proposed methods for spike train inference from calcium imaging data. PMID:23860257

  17. Predicted detection rates of regional-scale meteorite impacts on Mars with the InSight short-period seismometer

    NASA Astrophysics Data System (ADS)

    Teanby, N. A.

    2015-08-01

    In 2016 NASA will launch the InSight discovery-class mission, which aims to study the detailed internal structure of Mars for the first time. Short- and long-period seismometers form a major component of InSight's payload and have the potential to detect seismic waves generated by meteorite impacts. Large globally detectable impact events producing craters with diameters of ∼ 100 m have been investigated previously and are likely to be rare (Teanby, N.A., Wookey, J. [2011]. Phys. Earth Planet. Int. 186, 70-80), but smaller impacts producing craters in the 0.5-20 m range are more numerous and potentially occur sufficiently often to be detectable on regional scales (≲1000 km). At these distances, seismic waves will have significant high frequency content and will be suited to detection with InSight's short-period seismometer SEIS-SP. In this paper I estimate the current martian crater production function from observations of new craters (Malin, M.C. et al. [2006]. Science 314, 1573-1577; Daubar, I.J. et al. [2013]. Icarus 225, 506-516), model results (Williams, J.P., Pathare, A.V., Aharonson, O. [2014]. Icarus 235, 23-36), and standard isochrons (Hartmann, W.K. [2005]. Icarus 174, 294-320). These impact rates are combined with an empirical relation between impact energy, source-receiver distance, and peak seismogram amplitude, derived from a compilation of seismic recordings of terrestrial and lunar impacts, chemical explosions, and nuclear tests. The resulting peak seismogram amplitude scaling law contains significant uncertainty, but can be used to predict impact detection rates. I estimate that for a short-period instrument, with a noise spectral density of 10-8 ms-2 Hz-1/2 in the 1-16 Hz frequency band, approximately 0.1-30 regional impacts per year should be detectable with a nominal value of 1-3 impacts per year. Therefore, small regional impacts are likely to be a viable source of seismic energy for probing Mars' crustal and upper mantle structure. This is

  18. Detection and estimation of volcanic eruption onset and mass flow rate using weather radar and infrasonic array

    NASA Astrophysics Data System (ADS)

    Marzano, Frank S.; Mereu, Luigi; Montopoli, Mario; Picciotti, Errico; Di Fabio, Saverio; Bonadonna, Costanza; Marchetti, Emanuele; Ripepe, Maurizio

    2015-04-01

    The explosive eruption of sub-glacial Eyjafjallajökull volcano in 2010 was of modest size, but ash was widely dispersed over Iceland and Europe. The Eyjafjallajökull pulsating explosive activity started on April 14 and ended on May 22. The combination of a prolonged and sustained ejection of volcanic ash and persistent northwesterly winds resulted in dispersal the volcanic cloud over a large part of Europe. Tephra dispersal from an explosive eruption is a function of multiple factors, including magma mass flow rate (MFR), degree of magma fragmentation, vent geometry, plume height, particle size distribution (PSD) and wind velocity. One of the most important geophysical parameters, derivable from the analysis of tephra deposits, is the erupted mass, which is essential for the source characterization and assessment of the associated hazards. MFR can then be derived by dividing the erupted mass by the eruption duration (if known) or based on empirical and analytical relations with plume height. Microwave weather radars at C and X band can provide plume height, ash concentration and loading, and, to some extent, PSD and MFR. Radar technology is well established and can nowadays provide fast three-dimensional (3D) scanning antennas together with Doppler and dual polarization capabilities. However, some factors can limit the detection and the accuracy of the radar products aforementioned. For example, the sensitivity of microwave radar measurements depends on the distance between the radar antenna and the target, the transmitter central wavelength, receiver minimum detachable power and the resolution volume. In addition, radar measurements are sensitive to particle sizes larger than few tens of microns thus limiting the radar-based quantitative estimates to the larger portion of the PSD. Volcanic activity produces infrasonic waves (i.e., acoustic waves below 20 Hz), which can propagate in the atmosphere useful for the remote monitoring of volcanic activity. Infrasound

  19. DETECTION OF OH{sup +} IN TRANSLUCENT INTERSTELLAR CLOUDS: NEW ELECTRONIC TRANSITIONS AND PROBING THE PRIMARY COSMIC RAY IONIZATION RATE

    SciTech Connect

    Zhao, D.; Linnartz, H.; Galazutdinov, G. A.; Krełowski, J.

    2015-06-01

    We present the detection of rotationally resolved electronic transitions in the OH{sup +} A{sup 3}Π–X{sup 3}Σ{sup −} (0, 0) and (1, 0) bands toward CD-32 4348, HD 63804, HD 78344, and HD 80077. These four translucent clouds have been studied in a recent Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph observational run. In total, seven absorption features of OH{sup +} are detected, and six of them are identified here for the first time, providing a precise tool to trace OH{sup +} in translucent interstellar clouds. An improved set of line positions and oscillator strengths is compiled to support our data interpretation. A dedicated analysis of the observed features in individual targets yields an accurate determination of OH{sup +} column densities. The results are applied to estimate the primary cosmic ray ionization rate in the investigated translucent clouds, which yields a typical value of ∼1.0 × 10{sup −16} s{sup −1}. In addition, following this work, two of the new interstellar features recently reported by Bhatt and Cami, at ∼3572.65 and 3346.96 Å, can be identified as OH{sup +} absorption lines now.

  20. In vivo Mn-enhanced MRI for early tumor detection and growth rate analysis in a mouse medulloblastoma model.

    PubMed

    Suero-Abreu, Giselle A; Praveen Raju, G; Aristizábal, Orlando; Volkova, Eugenia; Wojcinski, Alexandre; Houston, Edward J; Pham, Diane; Szulc, Kamila U; Colon, Daniel; Joyner, Alexandra L; Turnbull, Daniel H

    2014-12-01

    Mouse models have increased our understanding of the pathogenesis of medulloblastoma (MB), the most common malignant pediatric brain tumor that often forms in the cerebellum. A major goal of ongoing research is to better understand the early stages of tumorigenesis and to establish the genetic and environmental changes that underlie MB initiation and growth. However, studies of MB progression in mouse models are difficult due to the heterogeneity of tumor onset times and growth patterns and the lack of clinical symptoms at early stages. Magnetic resonance imaging (MRI) is critical for noninvasive, longitudinal, three-dimensional (3D) brain tumor imaging in the clinic but is limited in resolution and sensitivity for imaging early MBs in mice. In this study, high-resolution (100 μm in 2 hours) and high-throughput (150 μm in 15 minutes) manganese-enhanced MRI (MEMRI) protocols were optimized for early detection and monitoring of MBs in a Patched-1 (Ptch1) conditional knockout (CKO) model. The high tissue contrast obtained with MEMRI revealed detailed cerebellar morphology and enabled detection of MBs over a wide range of stages including pretumoral lesions as early as 2 to 3 weeks postnatal with volumes close to 0.1 mm(3). Furthermore, longitudinal MEMRI allowed noninvasive monitoring of tumors and demonstrated that lesions within and between individuals have different tumorigenic potentials. 3D volumetric studies allowed quantitative analysis of MB tumor morphology and growth rates in individual Ptch1-CKO mice. These results show that MEMRI provides a powerful method for early in vivo detection and longitudinal imaging of MB progression in the mouse brain. PMID:25499213

  1. Detection of Driver Drowsiness Using Wavelet Analysis of Heart Rate Variability and a Support Vector Machine Classifier

    PubMed Central

    Li, Gang; Chung, Wan-Young

    2013-01-01

    Driving while fatigued is just as dangerous as drunk driving and may result in car accidents. Heart rate variability (HRV) analysis has been studied recently for the detection of driver drowsiness. However, the detection reliability has been lower than anticipated, because the HRV signals of drivers were always regarded as stationary signals. The wavelet transform method is a method for analyzing non-stationary signals. The aim of this study is to classify alert and drowsy driving events using the wavelet transform of HRV signals over short time periods and to compare the classification performance of this method with the conventional method that uses fast Fourier transform (FFT)-based features. Based on the standard shortest duration for FFT-based short-term HRV evaluation, the wavelet decomposition is performed on 2-min HRV samples, as well as 1-min and 3-min samples for reference purposes. A receiver operation curve (ROC) analysis and a support vector machine (SVM) classifier are used for feature selection and classification, respectively. The ROC analysis results show that the wavelet-based method performs better than the FFT-based method regardless of the duration of the HRV sample that is used. Finally, based on the real-time requirements for driver drowsiness detection, the SVM classifier is trained using eighty FFT and wavelet-based features that are extracted from 1-min HRV signals from four subjects. The averaged leave-one-out (LOO) classification performance using wavelet-based feature is 95% accuracy, 95% sensitivity, and 95% specificity. This is better than the FFT-based results that have 68.8% accuracy, 62.5% sensitivity, and 75% specificity. In addition, the proposed hardware platform is inexpensive and easy-to-use. PMID:24316564

  2. More Specific Signal Detection in Functional Magnetic Resonance Imaging by False Discovery Rate Control for Hierarchically Structured Systems of Hypotheses

    PubMed Central

    Schildknecht, Konstantin; Tabelow, Karsten; Dickhaus, Thorsten

    2016-01-01

    Signal detection in functional magnetic resonance imaging (fMRI) inherently involves the problem of testing a large number of hypotheses. A popular strategy to address this multiplicity is the control of the false discovery rate (FDR). In this work we consider the case where prior knowledge is available to partition the set of all hypotheses into disjoint subsets or families, e. g., by a-priori knowledge on the functionality of certain regions of interest. If the proportion of true null hypotheses differs between families, this structural information can be used to increase statistical power. We propose a two-stage multiple test procedure which first excludes those families from the analysis for which there is no strong evidence for containing true alternatives. We show control of the family-wise error rate at this first stage of testing. Then, at the second stage, we proceed to test the hypotheses within each non-excluded family and obtain asymptotic control of the FDR within each family at this second stage. Our main mathematical result is that this two-stage strategy implies asymptotic control of the FDR with respect to all hypotheses. In simulations we demonstrate the increased power of this new procedure in comparison with established procedures in situations with highly unbalanced families. Finally, we apply the proposed method to simulated and to real fMRI data. PMID:26914144

  3. More Specific Signal Detection in Functional Magnetic Resonance Imaging by False Discovery Rate Control for Hierarchically Structured Systems of Hypotheses.

    PubMed

    Schildknecht, Konstantin; Tabelow, Karsten; Dickhaus, Thorsten

    2016-01-01

    Signal detection in functional magnetic resonance imaging (fMRI) inherently involves the problem of testing a large number of hypotheses. A popular strategy to address this multiplicity is the control of the false discovery rate (FDR). In this work we consider the case where prior knowledge is available to partition the set of all hypotheses into disjoint subsets or families, e. g., by a-priori knowledge on the functionality of certain regions of interest. If the proportion of true null hypotheses differs between families, this structural information can be used to increase statistical power. We propose a two-stage multiple test procedure which first excludes those families from the analysis for which there is no strong evidence for containing true alternatives. We show control of the family-wise error rate at this first stage of testing. Then, at the second stage, we proceed to test the hypotheses within each non-excluded family and obtain asymptotic control of the FDR within each family at this second stage. Our main mathematical result is that this two-stage strategy implies asymptotic control of the FDR with respect to all hypotheses. In simulations we demonstrate the increased power of this new procedure in comparison with established procedures in situations with highly unbalanced families. Finally, we apply the proposed method to simulated and to real fMRI data.

  4. A non-contact capacitance based electrocardiograph and associated heart-rate detection using enhanced Fourier interpolation method.

    PubMed

    Kumar Thakur, Rupak; Anoop, C S

    2015-08-01

    Cardio-vascular health monitoring has gained considerable attention in the recent years. Principle of non-contact capacitive electrocardiograph (ECG) and its applicability as a valuable, low-cost, easy-to-use scheme for cardio-vascular health monitoring has been demonstrated in some recent research papers. In this paper, we develop a complete non-contact ECG system using a suitable front-end electronic circuit and a heart-rate (HR) measurement unit using enhanced Fourier interpolation technique. The front-end electronic circuit is realized using low-cost, readily available components and the proposed HR measurement unit is designed to achieve fairly accurate results. The entire system has been extensively tested to verify its efficacy and test results show that the developed system can estimate HR with an accuracy of ±2 beats. Detailed tests have been conducted to validate the performance of the system for different cloth thicknesses of the subject. Some basic tests which illustrate the application of the proposed system for heart-rate variability estimation has been conducted and results reported. The developed system can be used as a portable, reliable, long-term cardiac health monitoring device and can be extended to human drowsiness detection.

  5. Human care system for heart-rate and human-movement trajectory in home and its application to detect mental disease

    NASA Astrophysics Data System (ADS)

    Hata, Yutaka; Kanazawa, Seigo; Endo, Maki; Tsuchiya, Naoki; Nakajima, Hiroshi

    2012-06-01

    This paper proposes a heart rate monitoring system for detecting autonomic nervous system by the heart rate variability using an air pressure sensor to diagnose mental disease. Moreover, we propose a human behavior monitoring system for detecting the human trajectory in home by an infrared camera. In day and night times, the human behavior monitoring system detects the human movement in home. The heart rate monitoring system detects the heart rate in bed in night time. The air pressure sensor consists of a rubber tube, cushion cover and pressure sensor, and it detects the heart rate by setting it to bed. It unconstraintly detects the RR-intervals; thereby the autonomic nervous system can be assessed. The autonomic nervous system analysis can examine the mental disease. While, the human behavior monitoring system obtains distance distribution image by an infrared camera. It classifies adult, child and the other object from distance distribution obtained by the camera, and records their trajectories. This behavior, i.e., trajectory in home, strongly corresponds to cognitive disorders. Thus, the total system can detect mental disease and cognitive disorders by uncontacted sensors to human body.

  6. Using Lorenz plot and Cardiac Sympathetic Index of heart rate variability for detecting seizures for patients with epilepsy.

    PubMed

    Jeppesen, Jesper; Beniczky, Sandor; Johansen, Peter; Sidenius, Per; Fuglsang-Frederiksen, Anders

    2014-01-01

    Tachycardia is often seen during epileptic seizures, but it also occurs during physical exercise. In order to assess whether focal epileptic seizures can be detected by short term moving window Heart Rate Variability (HRV) analysis, we modified the geometric HRV method, Lorenz plot, to consist of only 30, 50 or 100 R-R intervals per analyzed window. From each window we calculated the longitudinal (L) and transverse (T) variability of Lorenz plot to retrieve the Cardiac Sympathetic Index (CSI) as (L/T) and "Modified CSI" (described in methods), and compared the maximum during the patient's epileptic seizures with that during the patient's own exercise and non-seizure sessions as control. All five analyzed patients had complex partial seizures (CPS) originating in the temporal lobe (11 seizures) during their 1-5 days long term video-EEG monitoring. All CPS with electroencephalographic correlation were selected for the HRV analysis. The CSI and Modified CSI were correspondently calculated after each heart beat depicting the prior 30, 50 and 100 R-R intervals at the time. CSI (30, 50 and 100) and Modified CSI (100) showed a higher maximum peak during seizures than exercise/non-seizure (121-296%) for 4 of the 5 patients within 4 seconds before till 60 seconds after seizure onset time even though exercise maximum HR exceeded that of the seizures. The results indicate a detectable, sudden and inordinate shift towards sympathetic overdrive in the sympathovagal balance of the autonomic nervous system just around seizure-onset for certain patients. This new modified moving window Lorenz plot method seems promising way of constructing a portable ECG-based epilepsy alarm for certain patients with epilepsy who needs aid during seizure.

  7. Light-addressable measurements of cellular oxygen consumption rates in microwell arrays based on phase-based phosphorescence lifetime detection

    PubMed Central

    Huang, Shih-Hao; Hsu, Yu-Hsuan; Wu, Chih-Wei; Wu, Chang-Jer

    2012-01-01

    A digital light modulation system that utilizes a modified commercial digital micromirror device (DMD) projector, which is equipped with a UV light-emitting diode as a light modulation source, has been developed to spatially direct excited light toward a microwell array device to detect the oxygen consumption rate (OCR) of single cells via phase-based phosphorescence lifetime detection. The microwell array device is composed of a combination of two components: an array of glass microwells containing Pt(II) octaethylporphine (PtOEP) as the oxygen-sensitive luminescent layer and a microfluidic module with pneumatically actuated glass lids set above the microwells to controllably seal the microwells of interest. By controlling the illumination pattern on the DMD, the modulated excitation light can be spatially projected to only excite the sealed microwell for cellular OCR measurements. The OCR of baby hamster kidney-21 fibroblast cells cultivated on the PtOEP layer within a sealed microwell has been successfully measured at 104 ± 2.96 amol s−1 cell−1. Repeatable and consistent measurements indicate that the oxygen measurements did not adversely affect the physiological state of the measured cells. The OCR of the cells exhibited a good linear relationship with the diameter of the microwells, ranging from 400 to 1000 μm and containing approximately 480 to 1200 cells within a microwell. In addition, the OCR variation of single cells in situ infected by Dengue virus with a different multiplicity of infection was also successfully measured in real-time. This proposed platform provides the potential for a wide range of biological applications in cell-based biosensing, toxicology, and drug discovery. PMID:24348889

  8. TOLERANCE TO COCAINE’S EFFECTS FOLLOWING CHRONIC ADMINISTRATION OF A DOSE WITHOUT DETECTED EFFECTS ON RESPONSE RATE OR PAUSE

    PubMed Central

    Minervini, Vanessa; Branch, Marc N.

    2014-01-01

    To observe tolerance to drug effects on operant behavior, the dose that researchers have often selected for chronic administration is one that disrupts, but does not abolish, responding. Some evidence suggests that tolerance may develop after chronic administration of relatively smaller doses. The purpose of the present experiment was to assess systematically effects of chronic administration of a dose without detected effect on responding. Specifically, response rates and postreinforcement pauses of five pigeons key pecking under a three-component multiple fixed-ratio schedule of food reinforcement were observed under chronic cocaine administration. We evaluated the effects of a range of doses (1.0 mg/kg to 17.0 mg/kg) during acute administration. The largest dose that failed to alter responding acutely then was administered chronically (1.0 mg/kg for one pigeon, 3.0 mg/kg for three pigeons, and 5.6 mg/kg for one pigeon). After 30 consecutive sessions of chronic administration, smaller and larger doses occasionally were substituted for the chronic dose. Pigeons then received presession saline administration for 30 consecutive sessions, and the postchronic effects of the series of doses on responding were determined. All subjects developed tolerance to doses of cocaine that initially had caused large decreases in rate, with the magnitude of the effects varying across components of the multiple schedule and subjects. Specifically, tolerance generally was greatest in the components with smaller ratios. Following postchronic saline administration, tolerance was usually diminished. Overall, the results demonstrate that under these conditions, repeated experience with disruptive effects of cocaine on food-maintained responding is not a necessary factor in the development of tolerance. PMID:24019029

  9. Automatic detection of a prefrontal cortical response to emotionally rated music using multi-channel near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Moghimi, Saba; Kushki, Azadeh; Power, Sarah; Guerguerian, Anne Marie; Chau, Tom

    2012-04-01

    Emotional responses can be induced by external sensory stimuli. For severely disabled nonverbal individuals who have no means of communication, the decoding of emotion may offer insight into an individual’s state of mind and his/her response to events taking place in the surrounding environment. Near-infrared spectroscopy (NIRS) provides an opportunity for bed-side monitoring of emotions via measurement of hemodynamic activity in the prefrontal cortex, a brain region known to be involved in emotion processing. In this paper, prefrontal cortex activity of ten able-bodied participants was monitored using NIRS as they listened to 78 music excerpts with different emotional content and a control acoustic stimuli consisting of the Brown noise. The participants rated their emotional state after listening to each excerpt along the dimensions of valence (positive versus negative) and arousal (intense versus neutral). These ratings were used to label the NIRS trial data. Using a linear discriminant analysis-based classifier and a two-dimensional time-domain feature set, trials with positive and negative emotions were discriminated with an average accuracy of 71.94% ± 8.19%. Trials with audible Brown noise representing a neutral response were differentiated from high arousal trials with an average accuracy of 71.93% ± 9.09% using a two-dimensional feature set. In nine out of the ten participants, response to the neutral Brown noise was differentiated from high arousal trials with accuracies exceeding chance level, and positive versus negative emotional differentiation accuracies exceeded the chance level in seven out of the ten participants. These results illustrate that NIRS recordings of the prefrontal cortex during presentation of music with emotional content can be automatically decoded in terms of both valence and arousal encouraging future investigation of NIRS-based emotion detection in individuals with severe disabilities.

  10. Detecting the spatial differentiation in settlement change rates during rapid urbanization in the Nanjing metropolitan region, China.

    PubMed

    Xu, Chi; Liu, Maosong; Yang, Xuejiao; Sheng, Sheng; Zhang, Mingjuan; Huang, Zheng

    2010-12-01

    Urbanization produced significant landscape changes throughout the world. China has been experiencing accelerated urbanization during the past decades. Rapid land use/land over conversion occurred nationwide in urbanization, manifesting noteworthy characteristics of landscape dynamics. In this study, we investigated the spatial differentiation in settlement change rates among 1-km(2) land units in the Nanjing metropolitan region, a representative rapidly urbanizing region in China. Remotely sensed detection using Landsat TM data of 1988-2006 showed that settlement increase, termed as positive growth (PG), was predominant in the study area; while settlement decrease, termed as negative growth (NG), also had a considerable proportion, which was mainly attributed to the increase of green lands and the shrink of rural settlements. Along the urban-rural gradient, PG and NG showed similar mono-peaked patterns. The urban fringe zone with a consistent width of about 4 km was identified as the hot zone of both PG and NG over the three unequal periods. For both PG and NG, high-rated changes tended to exhibit more aggregative patterns along the gradient in the urban fringe zone. Settlement changes showed apparent anisotropy across directions. The directional distribution of PG was significantly negatively correlated to the topographic variables, suggesting that the mountains constrained urban expansion in an "area-weighted inverse-distance power" form. Significant correlation between PG and NG in a time-lagged manner showed the "increase-decrease" fluctuation occurred in settlement changes, reflecting the "urban expansion-land reconfiguration" process in rapid urbanization in Nanjing.

  11. The Goalposts Have Moved: Can Surgery Residents Meet Updated Quality Benchmarks for Adenoma Detection Rate in Colonoscopy?

    PubMed

    Ortolani, John B; Tershak, Daniel R; Ferrara, John J; Paget, Charles J

    2016-09-01

    The American Society for Gastrointestinal Endoscopy (ASGE)/American College of Gastroenterology Task Force (ACGTF) on Quality in Endoscopy released updated quality benchmarks for colonoscopy in 2015. Our initial study concluded that surgery residents could perform safe and competent screening colonoscopy within a structured endoscopy curriculum. In this follow-up study, we sought to determine whether surgery residents could achieve the increased adenoma detection rate (ADR) benchmarks endorsed by the ASGE/ACGTF. An Institutional Review Board-approved prospective analysis of colonoscopies performed by five postgraduate year 2 and 3 general surgery residents from 2013 to 2015 was completed. All colonoscopies were performed under the direct supervision of surgical endoscopists after each resident passed a structured endoscopy simulation curriculum. The following ASGE/ACG quality metrics were recorded: bowel preparation quality; cecal intubation rate; polyp and ADRs; and, complications. Power analysis determined that 108 procedures were required for an 80 per cent probability of data analysis accuracy. About 135 screening and diagnostic colonoscopies were performed. Bowel prep was considered "adequate" in 90 per cent of cases. The cecum was reached independently in 95 per cent of cases. Polyp(s) were visualized and removed in 39 per cent of patients. The overall ADR was 31.8 per cent (>25%). Male ADR was 38.7 per cent (>30%). Female ADR was 26.0 per cent (>20%). Average polyp size was 8.7 mm (range: 1-22 mm). One patient was readmitted for postpolypectomy syndrome, and successfully managed nonoperatively. In conclusion, using our structured endoscopy curriculum, surgery residents achieved ADRs fully consistent with the updated benchmark values endorsed by the ASGE/ACGTF.

  12. Detection Rates of Cortical Auditory Evoked Potentials at Different Sensation Levels in Infants with Sensory/Neural Hearing Loss and Auditory Neuropathy Spectrum Disorder.

    PubMed

    Gardner-Berry, Kirsty; Chang, Hsiuwen; Ching, Teresa Y C; Hou, Sanna

    2016-02-01

    With the introduction of newborn hearing screening, infants are being diagnosed with hearing loss during the first few months of life. For infants with a sensory/neural hearing loss (SNHL), the audiogram can be estimated objectively using auditory brainstem response (ABR) testing and hearing aids prescribed accordingly. However, for infants with auditory neuropathy spectrum disorder (ANSD) due to the abnormal/absent ABR waveforms, alternative measures of auditory function are needed to assess the need for amplification and evaluate whether aided benefit has been achieved. Cortical auditory evoked potentials (CAEPs) are used to assess aided benefit in infants with hearing loss; however, there is insufficient information regarding the relationship between stimulus audibility and CAEP detection rates. It is also not clear whether CAEP detection rates differ between infants with SNHL and infants with ANSD. This study involved retrospective collection of CAEP, hearing threshold, and hearing aid gain data to investigate the relationship between stimulus audibility and CAEP detection rates. The results demonstrate that increases in stimulus audibility result in an increase in detection rate. For the same range of sensation levels, there was no difference in the detection rates between infants with SNHL and ANSD. PMID:27587922

  13. Effects of fixed time AI and AI at detected estrus on conception rate in smallholder zebu and crossbred heifers and cows subjected to double PGF2α administration.

    PubMed

    Gugssa, Tadesse; Ashebir, Gebregiorgis; Yayneshet, Tesfay

    2016-08-01

    The study was conducted to evaluate estrus response, time to the onset of estrus, and conception rate at fixed time AI and AI at detected estrus in local and crossbred heifers and cows subjected to double administration of PGF2α. One hundred twenty local (heifers, n = 27; cows, n = 33) and crossbreds (heifers, n = 21; cows, n = 39) were used for the study. About 63 and 85.7 % of the local and crossbred heifers, respectively, exhibited estrus. Similarly, all crossbred cows and 90.9 % of local cows showed estrus. Most heifers came to estrus between 48 and 72 h while cows exhibited behavioral signs of estrus between 72 and 96 h. AI at detected estrus resulted in higher conception rate than fixed time AI. Pregnancy per artificial insemination was higher in AI at detected estrus than fixed time AI. Accurate estrus detection followed by insemination are crucial factors in maximizing pregnancy, and this study has demonstrated that conception rate in smallholder heifers and cows should be inseminated following estrus detection to maximize the conception rate of the animals. PMID:27184042

  14. Heart Rate Variability for Early Detection of Cardiac Iron Deposition in Patients with Transfusion-Dependent Thalassemia

    PubMed Central

    Silvilairat, Suchaya; Charoenkwan, Pimlak; Saekho, Suwit; Tantiworawit, Adisak; Phrommintikul, Arintaya; Srichairatanakool, Somdet; Chattipakorn, Nipon

    2016-01-01

    Background Iron overload cardiomyopathy remains the major cause of death in patients with transfusion-dependent thalassemia. Cardiac T2* magnetic resonance imaging is costly yet effective in detecting cardiac iron accumulation in the heart. Heart rate variability (HRV) has been used to evaluate cardiac autonomic function and is depressed in cases of thalassemia. We evaluated whether HRV could be used as an indicator for early identification of cardiac iron deposition. Methods One hundred and one patients with transfusion-dependent thalassemia were enrolled in this study. The correlation between recorded HRV and hemoglobin, non-transferrin bound iron (NTBI), serum ferritin and cardiac T2* were evaluated. Results The median age was 18 years (range 8–59 years). The patient group with a 5-year mean serum ferritin >5,000 ng/mL included significantly more homozygous β-thalassemia and splenectomized patients, had lower hemoglobin levels, and had more cardiac iron deposit than all other groups. Anemia strongly influenced all domains of HRV. After adjusting for anemia, neither serum ferritin nor NTBI impacted the HRV. However cardiac T2* was an independent predictor of HRV, even after adjusting for anemia. For receiver operative characteristic (ROC) curve analysis of cardiac T2* ≤20 ms, only mean ferritin in the last 12 months and the average of the standard deviation of all R-R intervals for all five-minute segments in the 24-hour recording were predictors for cardiac T2* ≤20 ms, with area under the ROC curve of 0.961 (p<0.0001) and 0.701 (p = 0.05), respectively. Conclusions Hemoglobin and cardiac T2* as significant predictors for HRV indicate that anemia and cardiac iron deposition result in cardiac autonomic imbalance. The mean ferritin in the last 12 months could be useful as the best indicator for further evaluation of cardiac risk. The ability of serum ferritin to predict cardiac risk is stronger than observed in other thalassemia cohorts. HRV might be a

  15. Detection of atrial high-rate events by continuous Home Monitoring: clinical significance in the heart failure–cardiac resynchronization therapy population

    PubMed Central

    Shanmugam, Nesan; Boerdlein, Annegret; Proff, Jochen; Ong, Peter; Valencia, Oswaldo; Maier, Sebastian K.G.; Bauer, Wolfgang R.; Paul, Vince; Sack, Stefan

    2012-01-01

    Aims Uncertainty exists over the importance of device-detected short-duration atrial arrhythmias. Continuous atrial diagnostics, through home monitoring (HM) technology (BIOTRONIK, Berlin, Germany), provides a unique opportunity to assess frequency and quantity of atrial fibrillation (AF) episodes defined as atrial high-rate events (AHRE). Methods and results Prospective data from 560 heart failure (HF) patients (age 67 ± 10 years, median ejection fraction 27%) patients with a cardiac resynchronization therapy (CRT) device capable of HM from two multi-centre studies were analysed. Atrial high-rate events burden was defined as the duration of mode switch in a 24-h period with atrial rates of >180 beats for at least 1% or total of 14 min per day. The primary endpoint was incidence of a thromboembolic (TE) event. Secondary endpoints were cardiovascular death, hospitalization because of AF, or worsening HF. Over a median 370-day follow-up AHRE occurred in 40% of patients with 11 (2%) patients developing TE complications and mortality rate of 4.3% (24 deaths, 16 with cardiovascular aetiology). Compared with patients without detected AHRE, patients with detected AHRE>3.8 h over a day were nine times more likely to develop TE complications (P= 0.006). The majority of patients (73%) did not show a temporal association with the detected atrial episode and their adverse event, with a mean interval of 46.7 ± 71.9 days (range 0–194) before the TE complication. Conclusion In a high-risk cohort of HF patients, device-detected atrial arrhythmias are associated with an increased incidence of TE events. A cut-off point of 3.8 h over 24 h was associated with significant increase in the event rate. Routine assessment of AHRE should be considered with other data when assessing stroke risk and considering anti-coagulation initiation and should also prompt the optimization of cardioprotective HF therapy in CRT patients. PMID:21933802

  16. The detection and upgrade rates of prostate adenocarcinoma following transperineal template-guided prostate biopsy – a tertiary referral centre experience

    PubMed Central

    Telford, Robert; Viney, Richard; Patel, Prashant

    2016-01-01

    Introduction We aim to present transperineal template-guided prostate biopsy (template biopsy) outcomes at a tertiary referral centre. Furthermore, to identify the detection rate of prostate cancer in those with a previous negative transrectal ultrasound guided prostate biopsy and the upgrade rate of those on active surveillance for Gleason 3 + 3 = 6 prostate adenocarcinoma. Material and methods We conducted a prospective study of 200 consecutive men who underwent template biopsy over a 22-month period in a tertiary referral centre, using a standard 24 region template prostate biopsy technique. Indications and histology results, as well as complications, were recorded. Results Median age was 67 years and median PSA was 10 ng/mL. Overall detection rate was 47%. 39.5% of cases with previous negative transrectal biopsies were found to have prostate adenocarcinoma. 47.5% of cases on active surveillance for Gleason 3 + 3 = 6 prostate adenocarcinoma were upgraded. The most frequent complication was acute urinary retention at a rate of 12.5%, however, the use of a single prophylactic dose of tamsulosin was found to be beneficial, with 13 cases needed to treat to prevent one episode. Conclusions Template biopsies are safe and efficacious with an overall detection rate of 47% in the present series. Due to the high detection rate, one must consider template biopsy following one negative transrectal biopsy where there is persistent clinical suspicion. Furthermore, those considering active surveillance for Gleason 3 + 3 = 6 disease should be offered template biopsy to confirm the grade of their disease. PMID:27123325

  17. The chemically homogeneous evolutionary channel for binary black hole mergers: rates and properties of gravitational-wave events detectable by advanced LIGO

    NASA Astrophysics Data System (ADS)

    de Mink, S. E.; Mandel, I.

    2016-08-01

    We explore the predictions for detectable gravitational-wave signals from merging binary black holes formed through chemically homogeneous evolution in massive short-period stellar binaries. We find that ˜500 events per year could be detected with advanced ground-based detectors operating at full sensitivity. We analyse the distribution of detectable events, and conclude that there is a very strong preference for detecting events with nearly equal components (mass ratio >0.66 at 90 per cent confidence in our default model) and high masses (total source-frame mass between 57 and 103 M⊙ at 90 per cent confidence). We consider multiple alternative variations to analyse the sensitivity to uncertainties in the evolutionary physics and cosmological parameters, and conclude that while the rates are sensitive to assumed variations, the mass distributions are robust predictions. Finally, we consider the recently reported results of the analysis of the first 16 double-coincident days of the O1 LIGO (Laser Interferometer Gravitational-wave Observatory) observing run, and find that this formation channel is fully consistent with the inferred parameters of the GW150914 binary black hole detection and the inferred merger rate.

  18. Relation between detection rate and inappropriate shocks in single versus dual chamber cardioverter-defibrillator--an analysis from the OPTION trial.

    PubMed

    Kolb, Christof; Sturmer, Marcio; Babuty, Dominique; Sick, Peter; Davy, Jean Marc; Molon, Giulio; Schwab, Jörg Otto; Mantovani, Giuseppe; Wickliffe, Andrew; Lennerz, Carsten; Semmler, Verena; Siot, Pierre-Henri; Reif, Sebastian

    2016-01-01

    The programming of implantable cardioverter-defibrillators (ICDs) influences inappropriate shock rates. The aim of the study is to analyse rates of patients with appropriate and inappropriate shocks according to detection zones in the OPTION trial. All patients received dual chamber (DC) ICDs randomly assigned to be programmed either to single chamber (SC) or to DC settings including PARAD+ algorithm. In a post-hoc analysis, rates of patients with inappropriate and appropriate shocks were calculated for shocks triggered at heart rates ≥ 170 bpm (ventricular tachycardia zone) and at rates ≥ 200 bpm (ventricular fibrillation zone). In the SC group, higher rates of patients with total and inappropriate shocks were delivered at heart rates ≥ 170 bpm than at rates ≥ 200 bpm (total shocks: 21.1% vs. 16.6%; p = 0.002; inappropriate shocks: 7.6% vs. 4.5%, p = 0.016; appropriate shocks: 15.2% vs. 13.5%; p = n.s.). No such differences were observed in the DC group (total shocks: 14.3% vs. 12.6%; p = n.s.; inappropriate shocks: 3.9% vs. 3.6%; p = n.s.; appropriate shocks: 12.2% vs. 10.4%; p = n.s.). The higher frequency of patients with total shocks with SC settings than with DC settings that benefit from PARAD+ was driven by a higher percentage of patients with inappropriate shocks in the VT zone (170-200 bpm) in the SC population. PMID:26892534

  19. Detection rate of actionable mutations in diverse cancers using a biopsy-free (blood) circulating tumor cell DNA assay

    PubMed Central

    Schwaederle, Maria; Husain, Hatim; Fanta, Paul T.; Piccioni, David E.; Kesari, Santosh; Schwab, Richard B.; Banks, Kimberly C.; Lanman, Richard B.; Talasaz, AmirAli; Parker, Barbara A.; Kurzrock, Razelle

    2016-01-01

    Analysis of cell-free DNA using next-generation sequencing (NGS) is a powerful tool for the detection/monitoring of alterations present in circulating tumor DNA (ctDNA). Plasma extracted from 171 patients with a variety of cancers was analyzed for ctDNA (54 genes and copy number variants (CNVs) in three genes (EGFR, ERBB2 and MET)). The most represented cancers were lung (23%), breast (23%), and glioblastoma (19%). Ninety-nine patients (58%) had at least one detectable alteration. The most frequent alterations were TP53 (29.8%), followed by EGFR (17.5%), MET (10.5%), PIK3CA (7%), and NOTCH1 (5.8%). In contrast, of 222 healthy volunteers, only one had an aberration (TP53). Ninety patients with non-brain tumors had a discernible aberration (65% of 138 patients; in 70% of non-brain tumor patients with an alteration, the anomaly was potentially actionable). Interestingly, nine of 33 patients (27%) with glioblastoma had an alteration (6/33 (18%) potentially actionable). Overall, sixty-nine patients had potentially actionable alterations (40% of total; 69.7% of patients (69/99) with alterations); 68 patients (40% of total; 69% of patients with alterations), by a Food and Drug Administration (FDA) approved drug. In summary, 65% of diverse cancers (as well as 27% of glioblastomas) had detectable ctDNA aberration(s), with the majority theoretically actionable by an approved agent. PMID:26848768

  20. CO detections and IRAS observations of bright radio spiral galaxies at cz equal or less than 9000 kilometers per second

    NASA Technical Reports Server (NTRS)

    Sanders, D. B.; Mirabel, I. F.

    1985-01-01

    CO emission has been detected from 20 of 21 bright radio spirals with strong extended nuclear sources, including the most distant (NGC 7674) and the most luminous (IC 4553 = Arp 220, NGC 6240) galaxies yet detected in CO. All of these galaxies are rich in molecular gas, with M total(H2) = 3 x 10 to the 8th - 2 x 10 to the 10th solar masses. IRAS observations show that they have a strong far-infrared (FIR) excess, with L(FIR)/L(B) approximately equal to 1-35 and L(FIR) (40-400 microns) approximately equal to 10 to the 10th - 10 to the 12th L solar masses. The primary luminosity source for these radio cores appears to be star formation in molecular clouds. A strong correlation is found between the FIR and extended 21 cm continuum flux, implying that the fraction of massive stars formed is independent of the star formation rate. The ratio L(FIR)/M(H2) provides a measure of the current rate of star formation, which is found to be a factor 3-20 larger in these galaxies than for the ensemble of molecular clouds in the Milky Way. At these rates their molecular gas will be depleted in about 10 to the 8th yr.

  1. Defining Treatment Response and Remission in Child Anxiety: Signal Detection Analysis Using the Pediatric Anxiety Rating Scale

    ERIC Educational Resources Information Center

    Caporino, Nicole E.; Brodman, Douglas M.; Kendall, Philip C.; Albano, Anne Marie; Sherrill, Joel; Piacentini, John; Sakolsky, Dara; Birmaher, Boris; Compton, Scott N.; Ginsburg, Golda; Rynn, Moira; McCracken, James; Gosch, Elizabeth; Keeton, Courtney; March, John; Walkup, John T.

    2013-01-01

    Objective: To determine optimal Pediatric Anxiety Rating Scale (PARS) percent reduction and raw score cut-offs for predicting treatment response and remission among children and adolescents with anxiety disorders. Method: Data were from a subset of youth (N = 438; 7-17 years of age) who participated in the Child/Adolescent Anxiety Multimodal Study…

  2. Evaluation of a laser scanning sensor on detection of complex shaped targets for variable-rate sprayer development

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sensors that can accurately measure canopy structures are prerequisites for development of advanced variable-rate sprayers. A 270° radial range laser sensor was evaluated for its accuracy to measure dimensions of target surfaces with complex shapes and sizes. An algorithm for data acquisition and 3-...

  3. Multi-scale heart rate dynamics detected by phase-rectified signal averaging predicts mortality after acute myocardial infarction

    PubMed Central

    Kisohara, Masaya; Stein, Phyllis K.; Yoshida, Yutaka; Suzuki, Mari; Iizuka, Narushi; Carney, Robert M.; Watkins, Lana L.; Freedland, Kenneth E.; Blumenthal, James A.; Hayano, Junichiro

    2013-01-01

    Aims Acceleration and deceleration capacity (AC and DC) for beat-to-beat short-term heart rate dynamics are powerful predictors of mortality after acute myocardial infarction (AMI). We examined if AC and DC for minute-order long-term heart rate dynamics also have independent predictive value. Methods and results We studied 24-hr Holter electrcardiograms in 708 post-AMI patients who were followed up for up to 30 months thereafter. Acceleration capacity and DC was calculated with the time scales of T (window size defining heart rate) and s (wavelet scale) from 1 to 500 s and compared their prognostic values with conventional measures (ACconv and DCconv) that were calculated with (T,s) = [1,2 (beat)]. During the follow-up, 47 patients died. Both increased ACconv and decreased DCconv predicted mortality (C statistic, 0.792 and 0.797). Concordantly, sharp peaks of C statistics were observed at (T,s) = [2,7 (sec)] for both increased AC and decreased DC (0.762 and 0.768), but there were larger peaks of C statistics at around [30,60 (sec)] for both (0.783 and 0.796). The C statistic was greater for DC than AC at (30,60) (P = 0.0012). Deceleration capacity at (30,60) was a significant predictor even after adjusted for ACconv (P = 0.020) and DCconv (P = 0.028), but the predictive power of AC at (30,60) was no longer significant. Conclusion A decrease in DC for minute-order long-term heart rate dynamics is a strong predictor for post-AMI mortality and the predictive power is independent of ACconv and DCconv for beat-to-beat short-term heart rate dynamics. PMID:23248218

  4. Multi-Target Tracking With Time-Varying Clutter Rate and Detection Profile: Application to Time-Lapse Cell Microscopy Sequences.

    PubMed

    Rezatofighi, Seyed Hamid; Gould, Stephen; Vo, Ba Tuong; Vo, Ba-Ngu; Mele, Katarina; Hartley, Richard

    2015-06-01

    Quantitative analysis of the dynamics of tiny cellular and sub-cellular structures, known as particles, in time-lapse cell microscopy sequences requires the development of a reliable multi-target tracking method capable of tracking numerous similar targets in the presence of high levels of noise, high target density, complex motion patterns and intricate interactions. In this paper, we propose a framework for tracking these structures based on the random finite set Bayesian filtering framework. We focus on challenging biological applications where image characteristics such as noise and background intensity change during the acquisition process. Under these conditions, detection methods usually fail to detect all particles and are often followed by missed detections and many spurious measurements with unknown and time-varying rates. To deal with this, we propose a bootstrap filter composed of an estimator and a tracker. The estimator adaptively estimates the required meta parameters for the tracker such as clutter rate and the detection probability of the targets, while the tracker estimates the state of the targets. Our results show that the proposed approach can outperform state-of-the-art particle trackers on both synthetic and real data in this regime. PMID:25594963

  5. Interphase Molecular Cytogenetic Detection Rates of Chronic Lymphocytic Leukemia-Specific Aberrations Are Higher in Cultivated Cells Than in Blood or Bone Marrow Smears.

    PubMed

    Alhourani, Eyad; Aroutiounian, Rouben; Harutyunyan, Tigran; Glaser, Anita; Schlie, Cordula; Pohle, Beate; Liehr, Thomas

    2016-08-01

    Banding cytogenetics is still the gold standard in many fields of leukemia diagnostics. However, in chronic lymphocytic leukemia (CLL), GTG-banding results are hampered by a low mitotic rate of the corresponding malignant lymphatic cells. Thus, interphase fluorescence in situ hybridization (iFISH) for the detection of specific cytogenetic aberrations is done nowadays as a supplement to or even instead of banding cytogenetics in many diagnostic laboratories. These iFISH studies can be performed on native blood or bone marrow smears or in nuclei after cultivation and stimulation by a suitable mitogen. As there are only few comparative studies with partially conflicting results for the detection rates of aberrations in cultivated and native cells, this question was studied in 38 CLL cases with known aberrations in 11q22.2, 11q22.3, 12, 13q14.3, 14q32.33, 17p13.1, or 18q21.32. The obtained results implicate that iFISH directly applied on smears is in general less efficient for the detection of CLL-specific genetic abnormalities than for cultivated cells. This also shows that applied cell culture conditions are well suited for malignant CLL cells. Thus, to detect malignant aberrant cells in CLL, cell cultivation and cytogenetic workup should be performed and the obtained material should be subjected to banding cytogenetics and iFISH. PMID:27315825

  6. Multi-Target Tracking With Time-Varying Clutter Rate and Detection Profile: Application to Time-Lapse Cell Microscopy Sequences.

    PubMed

    Rezatofighi, Seyed Hamid; Gould, Stephen; Vo, Ba Tuong; Vo, Ba-Ngu; Mele, Katarina; Hartley, Richard

    2015-06-01

    Quantitative analysis of the dynamics of tiny cellular and sub-cellular structures, known as particles, in time-lapse cell microscopy sequences requires the development of a reliable multi-target tracking method capable of tracking numerous similar targets in the presence of high levels of noise, high target density, complex motion patterns and intricate interactions. In this paper, we propose a framework for tracking these structures based on the random finite set Bayesian filtering framework. We focus on challenging biological applications where image characteristics such as noise and background intensity change during the acquisition process. Under these conditions, detection methods usually fail to detect all particles and are often followed by missed detections and many spurious measurements with unknown and time-varying rates. To deal with this, we propose a bootstrap filter composed of an estimator and a tracker. The estimator adaptively estimates the required meta parameters for the tracker such as clutter rate and the detection probability of the targets, while the tracker estimates the state of the targets. Our results show that the proposed approach can outperform state-of-the-art particle trackers on both synthetic and real data in this regime.

  7. Detectability of the Eurasian otter by standard surveys: an approach using marking intensity to estimate false negative rates

    NASA Astrophysics Data System (ADS)

    Balestrieri, Alessandro; Remonti, Luigi; Prigioni, Claudio

    2011-01-01

    False negative detections may bias the surveys for rare species and reduce the reliability of models based on the proportion of occupied patches. We assessed the detectability of the Eurasian otter Lutra lutra through the standard survey method by analysing the detection history of 28 sampling stretches surveyed monthly between March 2001 and January 2003. Each survey negative for otter spraints was considered as a false negative if the otter had been recorded in the previous and/or following month (respectively, cFN and FN). Otter marking intensity (MI) (MI=N° of spraints per kilometre) was calculated and assumed to represent an index of its relative abundance. Spraints were found in 81.7% of all surveys. Yearly MI ranged from 1.02 to 101.4 spraints per kilometre. In 2002, mean MI was significantly lower than in the previous year, while no clear seasonal trend could be outlined. The minimum number of surveys required to establish the occurrence of the otter, as estimated by a probability model, was 2.6 and was inversely related to MI. For a sub-sample of 18 sampling stretches, the relation between the frequency of both cFN and FN and five variables of potential interest for otters was tested by means of stepwise linear multiple regressions, yielding two highly significant models, which both included only MI as the explanatory variable. The frequency of both FN and cFN was correlated to MI and the resulting equations used to assess the percentage of surveys positive for otters in both years. After the correction for non-detections, otter site occupancy did not vary between the 2 years, except for one river when applying the more conservative estimate of false negatives (cFN). Multiple visits and the assessing of MI should become standard components of otter surveys. This approach has broad applicability and may be applied to assess the large-scale distribution of other rare or elusive mammalian carnivores.

  8. REVISITING COINCIDENCE RATE BETWEEN GRAVITATIONAL WAVE DETECTION AND SHORT GAMMA-RAY BURST FOR THE ADVANCED AND THIRD GENERATION

    SciTech Connect

    Regimbau, T.; Siellez, K.; Meacher, D.; Gendre, B.; Boër, M.

    2015-01-20

    We use realistic Monte Carlo simulations including both gravitational-wave (GW) and short gamma-ray burst (sGRB) selection effects to revisit the coincident rate of binary systems composed of two neutron stars or a neutron star and a black hole. We show that the fraction of GW triggers that can be observed in coincidence with sGRBs is proportional to the beaming factor at z = 0, but increases with the distance until it reaches 100% at the GW detector horizon distance. When this is taken into account the rate is improved by a factor of three compared to the simple beaming factor correction. We provide an estimate of the performance future GRB detectors should achieve in order to fully exploit the potentiality of the planned third-generation GW antenna Einstein Telescope, and we propose a simple method to constrain the beaming angle of sGRBs.

  9. "Rate My Therapist": Automated Detection of Empathy in Drug and Alcohol Counseling via Speech and Language Processing

    PubMed Central

    Xiao, Bo; Imel, Zac E.; Georgiou, Panayiotis G.; Atkins, David C.; Narayanan, Shrikanth S.

    2015-01-01

    The technology for evaluating patient-provider interactions in psychotherapy–observational coding–has not changed in 70 years. It is labor-intensive, error prone, and expensive, limiting its use in evaluating psychotherapy in the real world. Engineering solutions from speech and language processing provide new methods for the automatic evaluation of provider ratings from session recordings. The primary data are 200 Motivational Interviewing (MI) sessions from a study on MI training methods with observer ratings of counselor empathy. Automatic Speech Recognition (ASR) was used to transcribe sessions, and the resulting words were used in a text-based predictive model of empathy. Two supporting datasets trained the speech processing tasks including ASR (1200 transcripts from heterogeneous psychotherapy sessions and 153 transcripts and session recordings from 5 MI clinical trials). The accuracy of computationally-derived empathy ratings were evaluated against human ratings for each provider. Computationally-derived empathy scores and classifications (high vs. low) were highly accurate against human-based codes and classifications, with a correlation of 0.65 and F-score (a weighted average of sensitivity and specificity) of 0.86, respectively. Empathy prediction using human transcription as input (as opposed to ASR) resulted in a slight increase in prediction accuracies, suggesting that the fully automatic system with ASR is relatively robust. Using speech and language processing methods, it is possible to generate accurate predictions of provider performance in psychotherapy from audio recordings alone. This technology can support large-scale evaluation of psychotherapy for dissemination and process studies. PMID:26630392

  10. "Rate My Therapist": Automated Detection of Empathy in Drug and Alcohol Counseling via Speech and Language Processing.

    PubMed

    Xiao, Bo; Imel, Zac E; Georgiou, Panayiotis G; Atkins, David C; Narayanan, Shrikanth S

    2015-01-01

    The technology for evaluating patient-provider interactions in psychotherapy-observational coding-has not changed in 70 years. It is labor-intensive, error prone, and expensive, limiting its use in evaluating psychotherapy in the real world. Engineering solutions from speech and language processing provide new methods for the automatic evaluation of provider ratings from session recordings. The primary data are 200 Motivational Interviewing (MI) sessions from a study on MI training methods with observer ratings of counselor empathy. Automatic Speech Recognition (ASR) was used to transcribe sessions, and the resulting words were used in a text-based predictive model of empathy. Two supporting datasets trained the speech processing tasks including ASR (1200 transcripts from heterogeneous psychotherapy sessions and 153 transcripts and session recordings from 5 MI clinical trials). The accuracy of computationally-derived empathy ratings were evaluated against human ratings for each provider. Computationally-derived empathy scores and classifications (high vs. low) were highly accurate against human-based codes and classifications, with a correlation of 0.65 and F-score (a weighted average of sensitivity and specificity) of 0.86, respectively. Empathy prediction using human transcription as input (as opposed to ASR) resulted in a slight increase in prediction accuracies, suggesting that the fully automatic system with ASR is relatively robust. Using speech and language processing methods, it is possible to generate accurate predictions of provider performance in psychotherapy from audio recordings alone. This technology can support large-scale evaluation of psychotherapy for dissemination and process studies. PMID:26630392

  11. High-rate real-time GPS network at Parkfield: Utility for detecting fault slip and seismic displacements

    USGS Publications Warehouse

    Langbein, J.; Bock, Y.

    2004-01-01

    A network of 13 continuous GPS stations near Parkfield, California has been converted from 30 second to 1 second sampling with positions of the stations estimated in real-time relative to a master station. Most stations are near the trace of the San Andreas fault, which exhibits creep. The noise spectra of the instantaneous 1 Hz positions show flicker noise at high frequencies and change to frequency independence at low frequencies; the change in character occurs between 6 to 8 hours. Our analysis indicates that 1-second sampled GPS can estimate horizontal displacements of order 6 mm at the 99% confidence level from a few seconds to a few hours. High frequency GPS can augment existing measurements in capturing large creep events and postseismic slip that would exceed the range of existing creepmeters, and can detect large seismic displacements. Copyright 2004 by the American Geophysical Union.

  12. The Effect Of Pixel Size On The Detection Rate Of Early Pulmonary Sarcoidosis In Digital Chest Radiographic Systems

    NASA Astrophysics Data System (ADS)

    MacMahon, Heber; Vyborny, Carl; Powell, Gregory; Doi, Kunio; Metz, Charles E.

    1984-08-01

    In digital radiography the pixel size used determines the potential spatial resolution of the system. The need for spatial resolution varies depending on the subject matter imaged. In many areas, including the chest, the minimum spatial resolution requirements have not been determined. Sarcoidosis is a disease which frequently causes subtle interstitial infiltrates in the lungs. As the initial step in an investigation designed to determine the minimum pixel size required in digital chest radiographic systems, we have studied 1 mm pixel digitized images on patients with early pulmonary sarcoidosis. The results of this preliminary study suggest that neither mild interstitial pulmonary infiltrates nor other abnormalities such as pneumothoraces may be detected reliably with 1 mm pixel digital images.

  13. Debris Disks in Aggregate: Using Hubble Space Telescope Coronagraphic Imagery to Understand the Scattered-Light Disk Detection Rate

    NASA Technical Reports Server (NTRS)

    Grady, Carol A.

    2011-01-01

    Despite more than a decade of coronagraphic imaging of debris disk candidate stars, only 16 have been imaged in scattered light. Since imaged disks provide our best insight into processes which sculpt disks, and can provide signposts of the presence of giant planets at distances which would elude radial velocity and transit surveys, we need to understand under what conditions we detect the disks in scattered light, how these disks differ from the majority of debris disks, and how to increase the yield of disks which are imaged with 0.1" angular resolution. In this talk, I will review what we have learned from a shallow HSTINICMOS NIR survey of debris disks, and present first results from our on-going HST /STIS optical imaging of bright scattered-light disks.

  14. Value of systematic intervention for chronic obstructive pulmonary disease in a regional Japanese city based on case detection rate and medical cost

    PubMed Central

    Tawara, Yuichi; Senjyu, Hideaki; Tanaka, Kenichiro; Tanaka, Takako; Asai, Masaharu; Kozu, Ryo; Tabusadani, Mitsuru; Honda, Sumihisa; Sawai, Terumitsu

    2015-01-01

    Objective We established a COPD taskforce for early detection, diagnosis, treatment, and intervention. We implemented a pilot intervention with a prospective and longitudinal design in a regional city. This study evaluates the usefulness of the COPD taskforce and intervention based on COPD case detection rate and per capita medical costs. Method We distributed a questionnaire to all 8,878 inhabitants aged 50–89 years, resident in Matsuura, Nagasaki Prefecture in 2006. Potentially COPD-positive persons received a pulmonary function test and diagnosis. We implemented ongoing detection, examination, education, and treatment interventions, performed follow-up examinations or respiratory lessons yearly, and supported the health maintenance of each patient. We compared COPD medical costs in Matsuura and in the rest of Nagasaki Prefecture using data from 2004 to 2013 recorded by the association of Nagasaki National Health Insurance Organization, assessing 10-year means and annual change. Results As of 2014, 256 people have received a definitive diagnosis of COPD; representing 31% of the estimated total number of COPD patients. Of the cases detected, 87.5% were mild or moderate in severity. COPD medical costs per patient in Matsuura were significantly lower than the rest of Nagasaki Prefecture, as was rate of increase in cost over time. Conclusion The COPD program in Matsuura enabled early detection and treatment of COPD patients and helped to lower the associated burden of medical costs. The success of this program suggests that a similar program could reduce the economic and human costs of COPD morbidity throughout Japan. PMID:26347397

  15. Citronellal reactions with ozone and OH radical: Rate constants and gas-phase products detected using PFBHA derivatization

    NASA Astrophysics Data System (ADS)

    Harrison, J. C.; Ham, J. E.; Wells, J. R.

    The bimolecular rate constants, kOH+citronellal, (150±40)×10 -12 cm 3 molecule -1 s -1 and, k+citronellal, (3.5±1.2)×10 -16 cm 3 molecule -1 s -1, were measured using the relative rate technique for the reactions of the hydroxyl radical (OH) and ozone (O 3) with 3,7-dimethyl-6-octen-1-al ((R)-(+)-citronellal) at (297±3) K and 1 atm total pressure. To more clearly define part of citronellal's indoor environment degradation mechanism, the products of the citronellal+OH and citronellal+O 3 reactions were also investigated. The positively identified citronellal/OH and citronellal/O 3 reaction products were: 3-methylhexanedial HC( dbnd O)CH 2CH 2CH(CH 3)CH 2C( dbnd O)H and 2-oxopropanal (methylglyoxal, CH 3C( dbnd O)C( dbnd O)H). The use of derivatizing agent O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) was used to propose 3-methylhexanedial as a major citronellal/OH and citronellal/O 3 reaction product. The elucidation of this reaction product was facilitated by mass spectrometry of the derivatized reaction products coupled with plausible citronellal/OH and citronellal/O 3 reaction mechanisms based on previously published volatile organic compound/OH and volatile organic compound/O 3 gas-phase reaction mechanisms.

  16. Relation between detection rate and inappropriate shocks in single versus dual chamber cardioverter-defibrillator – an analysis from the OPTION trial

    PubMed Central

    Kolb, Christof; Sturmer, Marcio; Babuty, Dominique; Sick, Peter; Davy, Jean Marc; Molon, Giulio; Schwab, Jörg Otto; Mantovani, Giuseppe; Wickliffe, Andrew; Lennerz, Carsten; Semmler, Verena; Siot, Pierre-Henri; Reif , Sebastian

    2016-01-01

    The programming of implantable cardioverter-defibrillators (ICDs) influences inappropriate shock rates. The aim of the study is to analyse rates of patients with appropriate and inappropriate shocks according to detection zones in the OPTION trial. All patients received dual chamber (DC) ICDs randomly assigned to be programmed either to single chamber (SC) or to DC settings including PARAD+ algorithm. In a post-hoc analysis, rates of patients with inappropriate and appropriate shocks were calculated for shocks triggered at heart rates ≥170 bpm (ventricular tachycardia zone) and at rates ≥200 bpm (ventricular fibrillation zone). In the SC group, higher rates of patients with total and inappropriate shocks were delivered at heart rates ≥170 bpm than at rates ≥200 bpm (total shocks: 21.1% vs. 16.6%; p = 0.002; inappropriate shocks: 7.6% vs. 4.5%, p = 0.016; appropriate shocks: 15.2% vs. 13.5%; p = n.s.). No such differences were observed in the DC group (total shocks: 14.3% vs. 12.6%; p = n.s.; inappropriate shocks: 3.9% vs. 3.6%; p = n.s.; appropriate shocks: 12.2% vs. 10.4%; p = n.s.). The higher frequency of patients with total shocks with SC settings than with DC settings that benefit from PARAD+ was driven by a higher percentage of patients with inappropriate shocks in the VT zone (170–200 bpm) in the SC population. PMID:26892534

  17. The mass-loss rates of red supergiants at low metallicity: detection of rotational CO emission from two red supergiants in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Matsuura, Mikako; Sargent, B.; Swinyard, Bruce; Yates, Jeremy; Royer, P.; Barlow, M. J.; Boyer, Martha; Decin, L.; Khouri, Theo; Meixner, Margaret; van Loon, Jacco Th.; Woods, Paul M.

    2016-11-01

    Using the PACS and SPIRE spectrometers on-board the Herschel Space Observatory, we obtained spectra of two red supergiants (RSGs) in the Large Magellanic Cloud (LMC). Multiple rotational CO emission lines (J = 6-5 to 15-14) and 15 H2O lines were detected from IRAS 05280-6910, and one CO line was detected from WOH G64. This is the first time that CO rotational lines have been detected from evolved stars in the LMC. Their CO line intensities are as strong as those of the Galactic RSG, VY CMa. Modelling the CO lines and the spectral energy distribution results in an estimated mass-loss rate for IRAS 05280-6910 of 3 × 10-4 M⊙ yr-1. The model assumes a gas-to-dust ratio and a CO-to-H2 abundance ratio is estimated from the Galactic values scaled by the LMC metallicity ([Fe/H] ˜ -0.3), i.e. that the CO-to-dust ratio is constant for Galactic and LMC metallicities within the uncertainties of the model. The key factor determining the CO line intensities and the mass-loss rate found to be the stellar luminosity.

  18. Time-gated single-photon detection module with 110 ps transition time and up to 80 MHz repetition rate

    SciTech Connect

    Buttafava, Mauro Boso, Gianluca; Ruggeri, Alessandro; Tosi, Alberto; Dalla Mora, Alberto

    2014-08-15

    We present the design and characterization of a complete single-photon counting module capable of time-gating a silicon single-photon avalanche diode with ON and OFF transition times down to 110 ps, at repetition rates up to 80 MHz. Thanks to this sharp temporal filtering of incoming photons, it is possible to reject undesired strong light pulses preceding (or following) the signal of interest, allowing to increase the dynamic range of optical acquisitions up to 7 decades. A complete experimental characterization of the module highlights its very flat temporal response, with a time resolution of the order of 30 ps. The instrument is fully user-configurable via a PC interface and can be easily integrated in any optical setup, thanks to its small and compact form factor.

  19. Detection of anomalous diffusion using confidence intervals of the scaling exponent with application to preterm neonatal heart rate variability

    NASA Astrophysics Data System (ADS)

    Bickel, David R.; Verklan, M. Terese; Moon, Jon

    1998-11-01

    The scaling exponent of the root mean square (rms) displacement quantifies the roughness of fractal or multifractal time series; it is equivalent to other second-order measures of scaling, such as the power-law exponents of the spectral density and autocorrelation function. For self-similar time series, the rms scaling exponent equals the Hurst parameter, which is related to the fractal dimension. A scaling exponent of 0.5 implies that the process is normal diffusion, which is equivalent to an uncorrelated random walk; otherwise, the process can be modeled as anomalous diffusion. Higher exponents indicate that the increments of the signal have positive correlations, while exponents below 0.5 imply that they have negative correlations. Scaling exponent estimates of successive segments of the increments of a signal are used to test the null hypothesis that the signal is normal diffusion, with the alternate hypothesis that the diffusion is anomalous. Dispersional analysis, a simple technique which does not require long signals, is used to estimate the scaling exponent from the slope of the linear regression of the logarithm of the standard deviation of binned data points on the logarithm of the number of points per bin. Computing the standard error of the scaling exponent using successive segments of the signal is superior to previous methods of obtaining the standard error, such as that based on the sum of squared errors used in the regression; the regression error is more of a measure of the deviation from power-law scaling than of the uncertainty of the scaling exponent estimate. Applying this test to preterm neonate heart rate data, it is found that time intervals between heart beats can be modeled as anomalous diffusion with negatively correlated increments. This corresponds to power spectra between 1/f2 and 1/f, whereas healthy adults are usually reported to have 1/f spectra, suggesting that the immaturity of the neonatal nervous system affects the scaling

  20. Statistical Approach to Decreasing the Error Rate of Noninvasive Prenatal Aneuploid Detection caused by Maternal Copy Number Variation

    PubMed Central

    Zhang, Han; Zhao, Yang-Yu; Song, Jing; Zhu, Qi-Ying; Yang, Hua; Zheng, Mei-Ling; Xuan, Zhao-Ling; Wei, Yuan; Chen, Yang; Yuan, Peng-Bo; Yu, Yang; Li, Da-Wei; Liang, Jun-Bin; Fan, Ling; Chen, Chong-Jian; Qiao, Jie

    2015-01-01

    Analyses of cell-free fetal DNA (cff-DNA) from maternal plasma using massively parallel sequencing enable the noninvasive detection of feto-placental chromosome aneuploidy; this technique has been widely used in clinics worldwide. Noninvasive prenatal tests (NIPT) based on cff-DNA have achieved very high accuracy; however, they suffer from maternal copy-number variations (CNV) that may cause false positives and false negatives. In this study, we developed an algorithm to exclude the effect of maternal CNV and refined the Z-score that is used to determine fetal aneuploidy. The simulation results showed that the algorithm is robust against variations of fetal concentration and maternal CNV size. We also introduced a method based on the discrepancy between feto-placental concentrations to help reduce the false-positive ratio. A total of 6615 pregnant women were enrolled in a prospective study to validate the accuracy of our method. All 106 fetuses with T21, 20 with T18, and three with T13 were tested using our method, with sensitivity of 100% and specificity of 99.97%. In the results, two cases with maternal duplications in chromosome 21, which were falsely predicted as T21 by the previous NIPT method, were correctly classified as normal by our algorithm, which demonstrated the effectiveness of our approach. PMID:26534864

  1. Optimizing Detection Rate and Characterization of Subtle Paroxysmal Neonatal Abnormal Facial Movements with Multi-Camera Video-Electroencephalogram Recordings.

    PubMed

    Pisani, Francesco; Pavlidis, Elena; Cattani, Luca; Ferrari, Gianluigi; Raheli, Riccardo; Spagnoli, Carlotta

    2016-06-01

    Objectives We retrospectively analyze the diagnostic accuracy for paroxysmal abnormal facial movements, comparing one camera versus multi-camera approach. Background Polygraphic video-electroencephalogram (vEEG) recording is the current gold standard for brain monitoring in high-risk newborns, especially when neonatal seizures are suspected. One camera synchronized with the EEG is commonly used. Methods Since mid-June 2012, we have started using multiple cameras, one of which point toward newborns' faces. We evaluated vEEGs recorded in newborns in the study period between mid-June 2012 and the end of September 2014 and compared, for each recording, the diagnostic accuracies obtained with one-camera and multi-camera approaches. Results We recorded 147 vEEGs from 87 newborns and found 73 episodes of paroxysmal facial abnormal movements in 18 vEEGs of 11 newborns with the multi-camera approach. By using the single-camera approach, only 28.8% of these events were identified (21/73). Ten positive vEEGs with multicamera with 52 paroxysmal facial abnormal movements (52/73, 71.2%) would have been considered as negative with the single-camera approach. Conclusions The use of one additional facial camera can significantly increase the diagnostic accuracy of vEEGs in the detection of paroxysmal abnormal facial movements in the newborns.

  2. Statistical Approach to Decreasing the Error Rate of Noninvasive Prenatal Aneuploid Detection caused by Maternal Copy Number Variation.

    PubMed

    Zhang, Han; Zhao, Yang-Yu; Song, Jing; Zhu, Qi-Ying; Yang, Hua; Zheng, Mei-Ling; Xuan, Zhao-Ling; Wei, Yuan; Chen, Yang; Yuan, Peng-Bo; Yu, Yang; Li, Da-Wei; Liang, Jun-Bin; Fan, Ling; Chen, Chong-Jian; Qiao, Jie

    2015-01-01

    Analyses of cell-free fetal DNA (cff-DNA) from maternal plasma using massively parallel sequencing enable the noninvasive detection of feto-placental chromosome aneuploidy; this technique has been widely used in clinics worldwide. Noninvasive prenatal tests (NIPT) based on cff-DNA have achieved very high accuracy; however, they suffer from maternal copy-number variations (CNV) that may cause false positives and false negatives. In this study, we developed an algorithm to exclude the effect of maternal CNV and refined the Z-score that is used to determine fetal aneuploidy. The simulation results showed that the algorithm is robust against variations of fetal concentration and maternal CNV size. We also introduced a method based on the discrepancy between feto-placental concentrations to help reduce the false-positive ratio. A total of 6615 pregnant women were enrolled in a prospective study to validate the accuracy of our method. All 106 fetuses with T21, 20 with T18, and three with T13 were tested using our method, with sensitivity of 100% and specificity of 99.97%. In the results, two cases with maternal duplications in chromosome 21, which were falsely predicted as T21 by the previous NIPT method, were correctly classified as normal by our algorithm, which demonstrated the effectiveness of our approach. PMID:26534864

  3. Comparison of the usefulness of heart rate variability versus exercise stress testing for the detection of myocardial ischemia in patients without known coronary artery disease.

    PubMed

    Goldkorn, Ronen; Naimushin, Alexey; Shlomo, Nir; Dan, Ariella; Oieru, Dan; Moalem, Israel; Rozen, Eli; Gur, Ilan; Levitan, Jacob; Rosenmann, David; Mogilewsky, Yakov; Klempfner, Robert; Goldenberg, Ilan

    2015-06-01

    Heart rate variability (HRV) has been shown to be attenuated in patients with coronary artery disease (CAD) and may, therefore, be possibly used for the early detection of myocardial ischemia. We aimed to evaluate the diagnostic yield of a novel short-term HRV algorithm for the detection of myocardial ischemia in subjects without known CAD. We prospectively enrolled 450 subjects without known CAD who were referred to tertiary medical centers for exercise stress testing (EST) with single-photon emission computed tomography myocardial perfusion imaging (MPI). All subjects underwent 1-hour Holter testing with subsequent HRV analysis before EST with MPI. The diagnostic yield of HRV analysis was compared with EST, using MPI as the gold standard for the noninvasive detection of myocardial ischemia. All subjects had intermediate pretest probability for CAD. Mean age was 62 years, 38% were women, 51% had hypertension, and 25% diabetes mellitus. HRV analysis showed superior sensitivity (77%) compared with standard EST (27%). After multivariate adjustment, HRV was independently associated with an 8.4-fold (p <0.001) increased likelihood for the detection of myocardial ischemia by MPI, whereas EST did not show a statistically significant association with a positive MPI (odds ratio 2.1; p = 0.12). Of subjects who were referred for subsequent coronary angiography, the respective sensitivities of HRV and EST for the detection of significant CAD were 73% versus 26%. Our data suggest that HRV can be used as an important noninvasive technique for the detection of myocardial ischemia in subjects without known CAD, providing superior sensitivity to conventional EST in this population.

  4. Study on the interrelated effects of capillary diameter, background electrolyte concentration, and flow rate in pressure assisted capillary electrophoresis with contactless conductivity detection.

    PubMed

    Mai, Thanh Duc; Hauser, Peter C

    2013-06-01

    A detailed study on the effect of the buffer concentration and the magnitude of the superimposed hydrodynamic flow on separation performance in CZE with contactless conductivity detection was carried out with capillaries of 10, 25, and 50 μm internal diameter. It was confirmed that capillaries of narrow internal diameters require higher buffer concentrations for best sensitivities. For all diameters it was found that electrodispersion was the most pronounced band-broadening factor for relatively long residence times. For shorter times, Joule heating related band broadening appears to be the most significant factor, which means that best separation efficiencies are obtained with the narrowest capillaries. As detection limits are as good for capillaries of 10 μm internal diameters as for the other diameters when using contactless conductivity detection, these narrow capillaries are, therefore, generally of benefit when employing this detection technique. Hydrodyamic flow was found to have only a very limited effect on band broadening; an effect was only noticeable for the 50 μm capillary and relatively high flow rates. PMID:23417350

  5. An 8.12 μW wavelet denoising chip for PPG detection and portable heart rate monitoring in 0.18 μm CMOS

    NASA Astrophysics Data System (ADS)

    Xiang, Li; Xu, Zhang; Peng, Li; Xiaohui, Hu; Hongda, Chen

    2016-05-01

    A low power wavelet denoising chip for photoplethysmography (PPG) detection and portable heart rate monitoring is presented. To eliminate noise and improve detection accuracy, Harr wavelet (HWT) is chosen as the processing tool. An optimized finite impulse response structure is proposed to lower the computational complexity of proposed algorithm, which is benefit for reducing the power consumption of proposed chip. The modulus maxima pair location module is design to accurately locate the PPG peaks. A clock control unit is designed to further reduce the power consumption of the proposed chip. Fabricated with the 0.18 μm N-well CMOS 1P6M technology, the power consumption of proposed chip is only 8.12 μW in 1 V voltage supply. Validated with PPG signals in multiparameter intelligent monitoring in intensive care databases and signals acquired by the wrist photoelectric volume detection front end, the proposed chip can accurately detect PPG signals. The average sensitivity and positive prediction are 99.91% and 100%, respectively.

  6. Improved Detection of Common Variants Associated with Schizophrenia and Bipolar Disorder Using Pleiotropy-Informed Conditional False Discovery Rate

    PubMed Central

    Andreassen, Ole A.; Thompson, Wesley K.; Schork, Andrew J.; Ripke, Stephan; Mattingsdal, Morten; Kelsoe, John R.; Kendler, Kenneth S.; O'Donovan, Michael C.; Rujescu, Dan; Werge, Thomas; Sklar, Pamela; Roddey, J. Cooper; Chen, Chi-Hua; McEvoy, Linda; Desikan, Rahul S.; Djurovic, Srdjan; Dale, Anders M.

    2013-01-01

    Several lines of evidence suggest that genome-wide association studies (GWAS) have the potential to explain more of the “missing heritability” of common complex phenotypes. However, reliable methods to identify a larger proportion of single nucleotide polymorphisms (SNPs) that impact disease risk are currently lacking. Here, we use a genetic pleiotropy-informed conditional false discovery rate (FDR) method on GWAS summary statistics data to identify new loci associated with schizophrenia (SCZ) and bipolar disorders (BD), two highly heritable disorders with significant missing heritability. Epidemiological and clinical evidence suggest similar disease characteristics and overlapping genes between SCZ and BD. Here, we computed conditional Q–Q curves of data from the Psychiatric Genome Consortium (SCZ; n = 9,379 cases and n = 7,736 controls; BD: n = 6,990 cases and n = 4,820 controls) to show enrichment of SNPs associated with SCZ as a function of association with BD and vice versa with a corresponding reduction in FDR. Applying the conditional FDR method, we identified 58 loci associated with SCZ and 35 loci associated with BD below the conditional FDR level of 0.05. Of these, 14 loci were associated with both SCZ and BD (conjunction FDR). Together, these findings show the feasibility of genetic pleiotropy-informed methods to improve gene discovery in SCZ and BD and indicate overlapping genetic mechanisms between these two disorders. PMID:23637625

  7. Improved detection of common variants associated with schizophrenia and bipolar disorder using pleiotropy-informed conditional false discovery rate.

    PubMed

    Andreassen, Ole A; Thompson, Wesley K; Schork, Andrew J; Ripke, Stephan; Mattingsdal, Morten; Kelsoe, John R; Kendler, Kenneth S; O'Donovan, Michael C; Rujescu, Dan; Werge, Thomas; Sklar, Pamela; Roddey, J Cooper; Chen, Chi-Hua; McEvoy, Linda; Desikan, Rahul S; Djurovic, Srdjan; Dale, Anders M

    2013-04-01

    Several lines of evidence suggest that genome-wide association studies (GWAS) have the potential to explain more of the "missing heritability" of common complex phenotypes. However, reliable methods to identify a larger proportion of single nucleotide polymorphisms (SNPs) that impact disease risk are currently lacking. Here, we use a genetic pleiotropy-informed conditional false discovery rate (FDR) method on GWAS summary statistics data to identify new loci associated with schizophrenia (SCZ) and bipolar disorders (BD), two highly heritable disorders with significant missing heritability. Epidemiological and clinical evidence suggest similar disease characteristics and overlapping genes between SCZ and BD. Here, we computed conditional Q-Q curves of data from the Psychiatric Genome Consortium (SCZ; n = 9,379 cases and n = 7,736 controls; BD: n = 6,990 cases and n = 4,820 controls) to show enrichment of SNPs associated with SCZ as a function of association with BD and vice versa with a corresponding reduction in FDR. Applying the conditional FDR method, we identified 58 loci associated with SCZ and 35 loci associated with BD below the conditional FDR level of 0.05. Of these, 14 loci were associated with both SCZ and BD (conjunction FDR). Together, these findings show the feasibility of genetic pleiotropy-informed methods to improve gene discovery in SCZ and BD and indicate overlapping genetic mechanisms between these two disorders.

  8. End-tidal CO₂ detection of an audible heart rate during neonatal cardiopulmonary resuscitation after asystole in asphyxiated piglets.

    PubMed

    Chalak, Lina F; Barber, Chad A; Hynan, Linda; Garcia, Damian; Christie, Lucy; Wyckoff, Myra H

    2011-05-01

    Even brief interruption of cardiac compressions significantly reduces critical coronary perfusion pressure during cardiopulmonary resuscitation (CPR). End-tidal CO₂ (ETCO₂) monitoring may provide a continuous noninvasive method of assessing return of spontaneous circulation (ROSC) without stopping to auscultate for heart rate (HR). However, the ETCO₂ value that correlates with an audible HR is unknown. Our objective was to determine the threshold ETCO₂ that is associated with ROSC after asphyxia-induced asystole. Neonatal swine (n = 46) were progressively asphyxiated until asystole occurred. Resuscitation followed current neonatal guidelines with initial ventilation with 100% O₂ followed by cardiac compressions followed by epinephrine for continued asystole. HR was auscultated every 30 s, and ETCO₂ was continuously recorded. A receiver operator curve was generated using the calculated sensitivity and specificity for various ETCO₂ values, where a positive test was defined as the presence of HR >60 bpm by auscultation. An ETCO₂ cut-off value of 14 mm Hg is the most sensitive ETCO₂ value with the least false positives. When using ETCO₂ to guide uninterrupted CPR in this model of asphyxia-induced asystole, auscultative confirmation of return of an adequate HR should be performed when ETCO₂ ≥ 14 mm Hg is achieved. Correlation during human neonatal CPR needs further investigation.

  9. Memory detection with the Concealed Information Test: a meta analysis of skin conductance, respiration, heart rate, and P300 data.

    PubMed

    Meijer, Ewout H; Selle, Nathalie Klein; Elber, Lotem; Ben-Shakhar, Gershon

    2014-09-01

    The Concealed Information Test (CIT) uses psychophysiological measures to determine the presence or absence of crime-related information in a suspect's memory. We conducted a meta-analysis on the validity of the CIT based on four physiological measures-skin conductance response (SCR), respiration line length (RLL), changes in heart rate (HR), and enhanced amplitudes of the P300 component of the event-related potential (P300). This meta-analysis relied on laboratory studies that used either the mock-crime or the personal-item paradigm. Results showed a mean effect size (d*) of 1.55 for SCR, 1.11 for RLL, 0.89 for HR, and 1.89 for P300. However, P300 outperformed SCR only in the personal-item paradigm, but not in the mock-crime paradigm. Motivation level, number of questions, publication year, and the inclusion of innocent participants emerged as significant moderators for the SCR, while only the type of paradigm used moderated the P300 effect. PMID:24916920

  10. MOST Detects SPBe Pulsations in HD 127756 and HD 217543: Asteroseismic Rotation Rates Independent of v sin i

    NASA Astrophysics Data System (ADS)

    Cameron, C.; Saio, H.; Kuschnig, R.; Walker, G. A. H.; Matthews, J. M.; Guenther, D. B.; Moffat, A. F. J.; Rucinski, S. M.; Sasselov, D.; Weiss, W. W.

    2008-09-01

    The MOST (Microvariability and Oscillations of Stars ) satellite has discovered SPBe (slowly pulsating Be) oscillations in the stars HD 127756 (B1/B2 Vne) and HD 217543 (B3 Vpe). For HD 127756, 30 significant frequencies are identified from 31 days of nearly continuous photometry; for HD 217543, up to 40 significant frequencies from 26 days of data. In both cases, the oscillations fall into three distinct frequency ranges, consistent with models of the stars. The variations are caused by nonradial g-modes (and possibly r-modes) distorted by rapid rotation and excited by the opacity mechanism near the iron opacity bump. A comparison of pulsation models and observed frequency groups yields a rotation frequency for each star, independently of vsin i. The rotation rates of these stars, as well as those of the SPBe stars previously discovered by MOST, HD 163868 and β CMi, are all close to their critical values. Based on data from the MOST satellite, a Canadian Space Agency mission, jointly operated by Dynacon, Inc., the University of Toronto Institute of Aerospace Studies, and the University of British Columbia with the assistance of the University of Vienna.

  11. VADASE: a new approach for real-time fast displacement detection - First application to Taiwan High-Rate GNSS Network

    NASA Astrophysics Data System (ADS)

    Hung, Huang-Kai; Rau, Ruey-Juin; Colosimo, Gabriele; Benedetti, Elisa; Branzanti, Mara; Crespi, Mattia; Mazzoni, Augusto

    2014-05-01

    The aim of this work is to show new possibilities for GNSS Permanent Network data processing offered by VADASE (Variometric Approach for Displacements Analysis Standalone Engine) to retrieve waveforms and coseismic displacements in real-time when an earthquake occurs. The main advantage of using GNSS receiver, in a complementary way with traditional seismic network, is that it can work without being affected by saturation, which commonly influence seismometers and accelerometers close to strong earthquake epicenters. VADASE was originally proposed in 2010 ([4],[5]) as the third way in GPS Seismology (in addition to Precise Point Positioning and Instantaneous Differential Positioning). The approach is based on time single differences of carrier phase observations continuously collected at high rate (1 Hz or higher) using a standalone GPS receiver and standard GPS broadcast products (orbits and clocks) that are available in real-time. Hence, one receiver works in standalone mode and the epoch-by-epoch displacements (equivalent to velocities) are estimated. Then, they are summed over the time interval when the earthquake occurred to retrieve coseismic displacements and waveforms. Considering time intervals limited to few minutes, the receiver displacements can be ascertained at a few centimeters accuracy level in real-time. The effectiveness of this approach was recognized by DLR (German Aerospace Agency), and VADASE was awarded the DLR Special Topic Prize and the Audience Award at the European Satellite Navigation Competition 2010. Moreover, VADASE potential was proven in the dramatic occasion of the Japanese earthquake occurred on March 11, 2011 ([3]-[6]); in fact VADASE was able to provide the first estimates of the displacements suffered at the IGS sites of MIZU and USUD [7], as soon as the data of these stations were available. The results were then confirmed by several other solutions based on the renown (DP, PPP) approaches. More recently, VADASE was applied

  12. VADASE: a new approach for real-time fast displacement detection - First application to Taiwan High-Rate GNSS Network

    NASA Astrophysics Data System (ADS)

    Hung, Huang-Kai; Rau, Ruey-Juin; Colosimo, Gabriele; Benedetti, Elisa; Branzanti, Mara; Crespi, Mattia; Mazzoni, Augusto

    2014-05-01

    The aim of this work is to show new possibilities for GNSS Permanent Network data processing offered by VADASE (Variometric Approach for Displacements Analysis Standalone Engine) to retrieve waveforms and coseismic displacements in real-time when an earthquake occurs. The main advantage of using GNSS receiver, in a complementary way with traditional seismic network, is that it can work without being affected by saturation, which commonly influence seismometers and accelerometers close to strong earthquake epicenters. VADASE was originally proposed in 2010 ([4],[5]) as the third way in GPS Seismology (in addition to Precise Point Positioning and Instantaneous Differential Positioning). The approach is based on time single differences of carrier phase observations continuously collected at high rate (1 Hz or higher) using a standalone GPS receiver and standard GPS broadcast products (orbits and clocks) that are available in real-time. Hence, one receiver works in standalone mode and the epoch-by-epoch displacements (equivalent to velocities) are estimated. Then, they are summed over the time interval when the earthquake occurred to retrieve coseismic displacements and waveforms. Considering time intervals limited to few minutes, the receiver displacements can be ascertained at a few centimeters accuracy level in real-time. The effectiveness of this approach was recognized by DLR (German Aerospace Agency), and VADASE was awarded the DLR Special Topic Prize and the Audience Award at the European Satellite Navigation Competition 2010. Moreover, VADASE potential was proven in the dramatic occasion of the Japanese earthquake occurred on March 11, 2011 ([3]-[6]); in fact VADASE was able to provide the first estimates of the displacements suffered at the IGS sites of MIZU and USUD [7], as soon as the data of these stations were available. The results were then confirmed by several other solutions based on the renown (DP, PPP) approaches. More recently, VADASE was applied

  13. Molecular Detection of the Carriage Rate of Four Intestinal Protozoa with Real-Time Polymerase Chain Reaction: Possible Overdiagnosis of Entamoeba histolytica in Nigeria

    PubMed Central

    Efunshile, Michael A.; Ngwu, Bethrand A. F.; Kurtzhals, Jørgen A. L.; Sahar, Sumrin; König, Brigitte; Stensvold, Christen R.

    2015-01-01

    Diarrhea remains the second largest killer of children worldwide, and Nigeria ranks number two on the list of global deaths attributable to diarrhea. Meanwhile, prevalence studies on potentially diarrheagenic protozoa in asymptomatic carriers using molecular detection methods remain scarce in sub-Saharan countries. To overcome sensitivity issues related to microscopic detection and identification of cysts in stool concentrates, real-time polymerase chain reaction (PCR) was used to analyze genomic DNAs extracted from stool samples from 199 healthy school children for Entamoeba histolytica, E. dispar, Giardia intestinalis, and Cryptosporidium. Questionnaires were administered for epidemiological data collection. E. histolytica was not detected in any of the samples, whereas Giardia (37.2%), E. dispar (18.6%), and Cryptosporidium (1%) were found. Most of the children sourced their drinking water from community wells (91%), while the majority disposed of feces in the bush (81.9%). Our study is the first to use real-time PCR to evaluate the epidemiology of E. histolytica, Giardia, and Cryptosporidium in Nigeria where previous studies using traditional diagnostic techniques have suggested higher and lower carriage rates of E. histolytica and Giardia, respectively. It is also the first study to accurately identify the prevalence of common potentially diarrheagenic protozoa in asymptomatic carriers in sub-Saharan Africa. PMID:26101274

  14. Molecular Detection of the Carriage Rate of Four Intestinal Protozoa with Real-Time Polymerase Chain Reaction: Possible Overdiagnosis of Entamoeba histolytica in Nigeria.

    PubMed

    Efunshile, Michael A; Ngwu, Bethrand A F; Kurtzhals, Jørgen A L; Sahar, Sumrin; König, Brigitte; Stensvold, Christen R

    2015-08-01

    Diarrhea remains the second largest killer of children worldwide, and Nigeria ranks number two on the list of global deaths attributable to diarrhea. Meanwhile, prevalence studies on potentially diarrheagenic protozoa in asymptomatic carriers using molecular detection methods remain scarce in sub-Saharan countries. To overcome sensitivity issues related to microscopic detection and identification of cysts in stool concentrates, real-time polymerase chain reaction (PCR) was used to analyze genomic DNAs extracted from stool samples from 199 healthy school children for Entamoeba histolytica, E. dispar, Giardia intestinalis, and Cryptosporidium. Questionnaires were administered for epidemiological data collection. E. histolytica was not detected in any of the samples, whereas Giardia (37.2%), E. dispar (18.6%), and Cryptosporidium (1%) were found. Most of the children sourced their drinking water from community wells (91%), while the majority disposed of feces in the bush (81.9%). Our study is the first to use real-time PCR to evaluate the epidemiology of E. histolytica, Giardia, and Cryptosporidium in Nigeria where previous studies using traditional diagnostic techniques have suggested higher and lower carriage rates of E. histolytica and Giardia, respectively. It is also the first study to accurately identify the prevalence of common potentially diarrheagenic protozoa in asymptomatic carriers in sub-Saharan Africa.

  15. [Electron microscopic detection rate of enteral viruses in diarrhea of dogs, cats, calves, swine and foals in the year 1988--electron microscopic study results].

    PubMed

    Biermann, U; Herbst, W; Krauss, H; Schliesser, T

    1989-12-01

    During 1988 fecal and gut samples of 641 dogs, 198 cats, 576 calves, 108 piglets and 64 foals with diarrhoea were investigated for virus infections by electron microscopy. In samples of dogs and cats parvovirus was detected at a proportion of 21.9% and 16.7%, respectively; rotavirus alone or together with coronavirus was found only in 0.3-1.5% of the specimens. In samples of calves rotavirus, as well as coronavirus dominated with a detection rate amounting to 17.4% and 26.6% respectively (including 4.5% of mixed infections); parvovirus was present in a ratio of 0.5%. Specimens of piglets mainly contained coronavirus (25.0%), and in lower percentages rotavirus (2.8%), rota- and coronaviruses (0.9%) and parvovirus (0.9%). In feces of foals rotavirus was detected in 6.3% and particles resembling picornavirus in 4.7% of cases. Not identifiable virus particles resembling corona-or picornaviruses were rarely found (between 0.6-2.5) also in specimens of the other animal species. PMID:2513799

  16. Comparison of the pregnancy rates and costs per calf born after fixed-time artificial insemination or artificial insemination after estrus detection in Bos indicus heifers.

    PubMed

    Edwards, S A A; Bo, G A; Chandra, K A; Atkinson, P C; McGowan, M R

    2015-01-01

    This study compared pregnancy rates (PRs) and costs per calf born after fixed-time artificial insemination (FTAI) or AI after estrus detection (i.e., estrus detection and AI, EDAI), before and after a single PGF2α treatment in Bos indicus (Brahman-cross) heifers. On Day 0, the body weight, body condition score, and presence of a CL (46% of heifers) were determined. The heifers were then alternately allocated to one of two FTAI groups (FTAI-1, n = 139) and (FTAI-2, n = 141) and an EDAI group (n = 273). Heifers in the FTAI groups received an intravaginal progesterone-releasing device (IPRD; 0.78 g of progesterone) and 1 mg of estradiol benzoate intramuscularly (im) on Day 0. Eight days later, the IPRD was removed and heifers received 500 μg of PGF2α and 300 IU of eCG im; 24 hours later, they received 1 mg estradiol benzoate im and were submitted to FTAI 30 to 34 hours later (54 and 58 hours after IPRD removal). Heifers in the FTAI-2 group started treatment 8 days after those in the FTAI-1 group. Heifers in the EDAI group were inseminated approximately 12 hours after the detection of estrus between Days 4 and 9 at which time the heifers that had not been detected in estrus received 500 μg of PGF2α im and EDAI continued until Day 13. Heifers in the FTAI groups had a higher overall PR (proportion pregnant as per the entire group) than the EDAI group (34.6% vs. 23.2%; P = 0.003), however, conception rate (PR of heifers submitted for AI) tended to favor the estrus detection group (34.6% vs. 44.1%; P = 0.059). The cost per AI calf born was estimated to be $267.67 and $291.37 for the FTAI and EDAI groups, respectively. It was concluded that in Brahman heifers typical of those annually mated in northern Australia FTAI compared with EDAI increases the number of heifers pregnant and reduces the cost per calf born.

  17. Comparison of the pregnancy rates and costs per calf born after fixed-time artificial insemination or artificial insemination after estrus detection in Bos indicus heifers.

    PubMed

    Edwards, S A A; Bo, G A; Chandra, K A; Atkinson, P C; McGowan, M R

    2015-01-01

    This study compared pregnancy rates (PRs) and costs per calf born after fixed-time artificial insemination (FTAI) or AI after estrus detection (i.e., estrus detection and AI, EDAI), before and after a single PGF2α treatment in Bos indicus (Brahman-cross) heifers. On Day 0, the body weight, body condition score, and presence of a CL (46% of heifers) were determined. The heifers were then alternately allocated to one of two FTAI groups (FTAI-1, n = 139) and (FTAI-2, n = 141) and an EDAI group (n = 273). Heifers in the FTAI groups received an intravaginal progesterone-releasing device (IPRD; 0.78 g of progesterone) and 1 mg of estradiol benzoate intramuscularly (im) on Day 0. Eight days later, the IPRD was removed and heifers received 500 μg of PGF2α and 300 IU of eCG im; 24 hours later, they received 1 mg estradiol benzoate im and were submitted to FTAI 30 to 34 hours later (54 and 58 hours after IPRD removal). Heifers in the FTAI-2 group started treatment 8 days after those in the FTAI-1 group. Heifers in the EDAI group were inseminated approximately 12 hours after the detection of estrus between Days 4 and 9 at which time the heifers that had not been detected in estrus received 500 μg of PGF2α im and EDAI continued until Day 13. Heifers in the FTAI groups had a higher overall PR (proportion pregnant as per the entire group) than the EDAI group (34.6% vs. 23.2%; P = 0.003), however, conception rate (PR of heifers submitted for AI) tended to favor the estrus detection group (34.6% vs. 44.1%; P = 0.059). The cost per AI calf born was estimated to be $267.67 and $291.37 for the FTAI and EDAI groups, respectively. It was concluded that in Brahman heifers typical of those annually mated in northern Australia FTAI compared with EDAI increases the number of heifers pregnant and reduces the cost per calf born. PMID:25284281

  18. Heart rate variability and stroke volume variability to detect central hypovolemia during spontaneous breathing and supported ventilation in young, healthy volunteers.

    PubMed

    Elstad, Maja; Walløe, Lars

    2015-04-01

    Cardiovascular oscillations exist in many different variables and may give important diagnostic and prognostic information in patients. Variability in cardiac stroke volume (SVV) is used in clinical practice for diagnosis of hypovolemia, but currently is limited to patients on mechanical ventilation. We investigated if SVV and heart rate variability (HRV) could detect central hypovolemia in spontaneously breathing humans: We also compared cardiovascular variability during spontaneous breathing with supported mechanical ventilation.Ten subjects underwent simulated central hypovolemia by lower body negative pressure (LBNP) with >10% reduction of cardiac stroke volume. The subjects breathed spontaneously and with supported mechanical ventilation. Heart rate, respiratory frequency and mean arterial blood pressure were measured. Stroke volume (SV) was estimated by ModelFlow (Finometer). Respiratory SVV was calculated by: 1) SVV% = (SVmax - SVmin)/SVmean during one respiratory cycle, 2) SVIntegral from the power spectra (Fourier transform) at 0.15-0.4 Hz and 3) SVV_norm = (√SVIntegral)/SVmean. HRV was calculated by the same methods.During spontaneous breathing two measures of SVV and all three measures of HRV were reduced during hypovolemia compared to baseline. During spontaneous breathing SVIntegral and HRV% were best to detect hypovolemia (area under receiver operating curve 0.81). HRV% ≤ 11% and SVIntegral ≤ 12 ml(2) differentiated between hypovolemia and baseline during spontaneous breathing.During supported mechanical ventilation, none of the three measures of SVV changed and two of the HRV measures were reduced during hypovolemia. Neither measures of SVV nor HRV were classified as a good detector of hypovolemia.We conclude that HRV% and SVIntegral detect hypovolemia during spontaneous breathing and both are candidates for further clinical testing. PMID:25799094

  19. Detection of Neptune-size planetary candidates with CoRoT data. Comparison with the planet occurrence rate derived from Kepler

    NASA Astrophysics Data System (ADS)

    Bonomo, A. S.; Chabaud, P. Y.; Deleuil, M.; Moutou, C.; Bouchy, F.; Cabrera, J.; Lanza, A. F.; Mazeh, T.; Aigrain, S.; Alonso, R.; Guterman, P.; Santerne, A.; Schneider, J.

    2012-11-01

    Context. The CoRoT space mission has been searching for transiting planets since the end of December 2006. It has led to the detection of about twenty Jupiter-size planets and three planets with radius Rp ≲ 5 R⊕. The latter are CoRoT-7b, the first super-Earth observed in transit, and two validated Neptunes, CoRoT-24b and c, in a multiple system. Aims: We aim to investigate the capability of CoRoT to detect small-size transiting planets in short-period orbits, and to compare the number of CoRoT planets with 2.0 ≤ Rp ≤ 4.0 R⊕ with the occurrence rate of small-size planets provided by the distribution of Kepler planetary candidates. Methods: We performed a test that simulates transits of super-Earths and Neptunes in real CoRoT light curves of six long observational runs and searches for them blindly by using the transit detection pipeline developed at the Laboratoire d'Astrophysique de Marseille. Results: The CoRoT detection rate of planets with radius between 2 and 4 R⊕ and orbital period P ≤ 20 days is 59% (31%) around stars brighter than r' = 14.0 (15.5). The vast majority of the missed planets went undetected because of a low transit signal-to-noise ratio (S/N). However, in some cases, additional instrumental or astrophysical noise may prevent even transits with relatively high S/N, i.e. S/N ≥ 10, from being revealed. By properly taking the CoRoT detection rate for Neptune-size planets (2 ≤ Rp ≤ 4 R⊕) and the transit probability into account, we found that according to the Kepler planet occurrence rate, CoRoT should have discovered 12 ± 2 Neptunes orbiting G and K dwarfs with P ≤ 17 days in six observational runs. This estimate must be compared with the validated Neptune CoRoT-24b and five CoRoT planetary candidates in the considered range of planetary radii, the nature of which is still unsolved. We thus found a disagreement with expectations from Kepler at 3σ or 5σ, assuming a blend fraction of 0% (six Neptunes) and 100% (one Neptune

  20. Low noise parametric amplifiers for radio astronomy observations at 18-21 cm wavelength

    NASA Technical Reports Server (NTRS)

    Kanevskiy, B. Z.; Veselov, V. M.; Strukov, I. A.; Etkin, V. S.

    1974-01-01

    The principle characteristics and use of SHF parametric amplifiers for radiometer input devices are explored. Balanced parametric amplifiers (BPA) are considered as the SHF signal amplifiers allowing production of the amplifier circuit without a special filter to achieve decoupling. Formulas to calculate the basic parameters of a BPA are given. A modulator based on coaxial lines is discussed as the input element of the SHF. Results of laboratory tests of the receiver section and long-term stability studies of the SHF sector are presented.

  1. VizieR Online Data Catalog: Millennium Arecibo 21-cm Survey. III. (Heiles+, 2004)

    NASA Astrophysics Data System (ADS)

    Heiles, C.; Troland, T. H.

    2004-05-01

    We outline the theory and practice of measuring the four Stokes parameters of spectral lines in emission/absorption observations. We apply these concepts to our Arecibo H I absorption line data and present the results. We include a detailed discussion of instrumental effects arising from polarized beam structure and its interaction with the spatially extended emission line structure. At Arecibo, linear polarization [Stokes (Q,U)] has much larger instrumental effects than circular (Stokes V). We show how to reduce the instrumental contributions to V and to evaluate upper limits to its remaining instrumental errors by using the (Q,U) results. These efforts work well for opacity spectra but not for emission spectra. Arecibo's large central blockage exacerbates these effects, particularly for emission profiles, and other telescopes with weaker sidelobes are not as susceptible. We present graphical results for 41 sources; we analyze these absorption spectra in terms of Gaussian components, which number 136, and present physical parameters including magnetic field for each. (1 data file).

  2. Adding Context to James Webb Space Telescope Surveys with Current and Future 21 cm Radio Observations

    NASA Astrophysics Data System (ADS)

    Beardsley, A. P.; Morales, M. F.; Lidz, A.; Malloy, M.; Sutter, P. M.

    2015-02-01

    Infrared and radio observations of the Epoch of Reionization promise to revolutionize our understanding of the cosmic dawn, and major efforts with the JWST, MWA, and HERA are underway. While measurements of the ionizing sources with infrared telescopes and the effect of these sources on the intergalactic medium with radio telescopes should be complementary, to date the wildly disparate angular resolutions and survey speeds have made connecting proposed observations difficult. In this paper we develop a method to bridge the gap between radio and infrared studies. While the radio images may not have the sensitivity and resolution to identify individual bubbles with high fidelity, by leveraging knowledge of the measured power spectrum we are able to separate regions that are likely ionized from largely neutral, providing context for the JWST observations of galaxy counts and properties in each. By providing the ionization context for infrared galaxy observations, this method can significantly enhance the science returns of JWST and other infrared observations.

  3. Cross-correlation cosmography with intensity mapping of the neutral hydrogen 21 cm emission

    NASA Astrophysics Data System (ADS)

    Pourtsidou, A.; Bacon, D.; Crittenden, R.

    2015-11-01

    The cross-correlation of a foreground density field with two different background convergence fields can be used to measure cosmographic distance ratios and constrain dark energy parameters. We investigate the possibility of performing such measurements using a combination of optical galaxy surveys and neutral hydrogen (HI) intensity mapping surveys, with emphasis on the performance of the planned Square Kilometre Array (SKA). Using HI intensity mapping to probe the foreground density tracer field and/or the background source fields has the advantage of excellent redshift resolution and a longer lever arm achieved by using the lensing signal from high redshift background sources. Our results show that, for our best SKA-optical configuration of surveys, a constant equation of state for dark energy can be constrained to ≃8 % for a sky coverage fsky=0.5 and assuming a σ (ΩDE)=0.03 prior for the dark energy density parameter. We also show that using the cosmic microwave background as the second source plane is not competitive, even when considering a COrE-like satellite.

  4. Will nonlinear peculiar velocity and inhomogeneous reionization spoil 21 cm cosmology from the epoch of reionization?

    PubMed

    Shapiro, Paul R; Mao, Yi; Iliev, Ilian T; Mellema, Garrelt; Datta, Kanan K; Ahn, Kyungjin; Koda, Jun

    2013-04-12

    The 21 cm background from the epoch of reionization is a promising cosmological probe: line-of-sight velocity fluctuations distort redshift, so brightness fluctuations in Fourier space depend upon angle, which linear theory shows can separate cosmological from astrophysical information. Nonlinear fluctuations in ionization, density, and velocity change this, however. The validity and accuracy of the separation scheme are tested here for the first time, by detailed reionization simulations. The scheme works reasonably well early in reionization (≲40% ionized), but not late (≳80% ionized).

  5. Cooling rate correction and Detection of mineralogical evolution during Thellier-Thellier's experiments on baked clays. Applications to French protohistoric structures

    NASA Astrophysics Data System (ADS)

    Lanos, P.; Hervé, G.; Chauvin, A.; Perron d'Arc, M.

    2011-12-01

    Archaeointensity protocols have been considerably improved since the last years to better detect multidomain (MD) grains effects or mineralogical evolutions during Thellier's experiments. Current published data respect more strict criteria and take into account the anisotropy of thermoremanent magnetization (TRM). However the effect of the cooling rate on the intensity of the TRM acquired during cooling, which depends on the type of the ferromagnetic grains, remains difficult to precisely quantify. The main problem is to estimate the true cooling rate of the archeological structures and usually a 24 hours cooling is assumed. An experimental study of 35 small bricks baked in two kilns during summer 2007 and 2008 (in Sallèles d'Aude, southern France) gives new elements about the cooling rate correction. The used kilns are of two different sizes, similar to classical archaeological structures. Intensity of the geomagnetic field (43 μT) in the kilns and the temperature decrease during the cooling (around 12 hours for the small kiln and 70 hours for the other one) were measured. Discrepancies between the TRM intensity after fast (1.5 hour in the laboratory) and low cooling of 24 hours are over a very wide range between -5 and +30%. The use of the true cooling rate of the kilns (respectively 12 and 72 hours) gives mean archaeointensities (43.8±1.8 μT and 42.7±2.2 μT) corresponding to the intensity of the field measured within them. By applying the usual cooling of 24 hours, the intensity of the field is underestimated by 3 μT in the small kiln and is overestimated by 3 μT in the bigger kiln. Consequently, a wrong cooling rate correction may explain the dispersion between archaeointensities. The second aspect of the presentation corresponds to the detection of mineralogical evolution during successive heatings of the Thellier-Thellier's protocol. This problem is particularly important for the millennia BC in Europe, as very well heated structures are less common

  6. Luminescence Imaging: (a) Multicolor Visualization of Ca(2+) Dynamics in Different Cellular Compartments and (b) Video-Rate Tumor Detection in a Freely Moving Mouse.

    PubMed

    Saito, Kenta; Nakano, Masahiro; Nagai, Takeharu

    2016-01-01

    Luminescence exerts an ideal optical readout for imaging living subjects including no external light source, whereas the dim luminescence and poor color pallet should be addressed for the better utilities. To address the demerits and to prevail the advantages, we developed a bright luminescent protein, named yellow Nano-lantern, exhibiting about 10-20 times brighter than wild-type RLuc. In this chapter, we demonstrate two luminescence-based protocols in detail: i.e., (a) multicolor visualization of Ca(2+) dynamics in different cellular compartments in a single cell using Ca(2+) indicators based on cyan- and orange-Nano-lanterns and (b) video-rate tumor detection in a freely moving mouse using yellow Nano-lantern. PMID:27424914

  7. What Level of Bowel Prep Quality Requires Early Repeat Colonoscopy: Systematic Review and Meta-Analysis of the Impact of Preparation Quality on Adenoma Detection Rate

    PubMed Central

    Clark, Brian T.; Rustagi, Tarun; Laine, Loren

    2015-01-01

    OBJECTIVES Current guidelines recommend early repeat colonoscopy when bowel preparation quality is inadequate, defined as inability to detect polyps > 5 mm, but no data link specific bowel preparation categories or scores to this definition. Nevertheless, most physicians use a shortened screening/surveillance interval in patients with intermediate-quality preparation. We determined whether different levels of bowel preparation quality are associated with differences in adenoma detection rates (ADRs: proportion of colonoscopies with ≥1 adenoma) to help guide decisions regarding early repeat colonoscopy—with primary focus on intermediate-quality preparation. METHODS MEDLINE and Embase were searched for studies with adenoma or polyp detection rate stratified by bowel preparation quality. Preparation quality definitions were standardized on the basis of Aronchick definitions (excellent/good/fair/poor/insufficient), and primary analyses of ADR trichotomized bowel preparation quality: high quality (excellent/good), intermediate quality (fair), and low quality (poor/insufficient). Dichotomized analyses of adequate (excellent/good/fair) vs. inadequate (poor/insufficient) were also performed. RESULTS Eleven studies met the inclusion criteria. The primary analysis, ADR with intermediate- vs. high-quality preparation, showed an odds ratio (OR) of 0.94 (0.80–1.10) and absolute risk difference of −1% (−3%, 2%). ADRs were significantly higher with both intermediate-quality and high-quality preparation vs. low-quality preparation: OR = 1.39 (1.08–1.79) and 1.41 (1.21–1.64), with absolute risk increases of 5% for both. ADR and advanced ADR were significantly higher with adequate vs. inadequate preparation: OR = 1.30 (1.19–1.42) and 1.30 (1.02–1.67). Studies did not report other relevant outcomes such as total adenomas per colonoscopy. CONCLUSIONS ADR is not significantly different with intermediate-quality vs. high-quality bowel preparation. Our results confirm

  8. Comparative Genomics Uncovers Unique Gene Turnover and Evolutionary Rates in a Gene Family Involved in the Detection of Insect Cuticular Pheromones

    PubMed Central

    Torres-Oliva, Montserrat; Almeida, Francisca C.; Sánchez-Gracia, Alejandro; Rozas, Julio

    2016-01-01

    Chemoreception is an essential process for the survival and reproduction of animals. Many of the proteins responsible for recognizing and transmitting chemical stimuli in insects are encoded by genes that are members of moderately sized multigene families. The members of the CheB family are specialized in gustatory-mediated detection of long-chain hydrocarbon pheromones in Drosophila melanogaster and play a central role in triggering and modulating mating behavior in this species. Here, we present a comprehensive comparative genomic analysis of the CheB family across 12 species of the Drosophila genus. We have identified a total of 102 new CheB genes in the genomes of these species, including a functionally divergent member previously uncharacterized in D. melanogaster. We found that, despite its relatively small repertory size, the CheB family has undergone multiple gain and loss events and various episodes of diversifying selection during the divergence of the surveyed species. Present estimates of gene turnover and coding sequence substitution rates show that this family is evolving faster than any known Drosophila chemosensory family. To date, only other insect gustatory-related genes among these families had shown evolutionary dynamics close to those observed in CheBs. Our findings reveal the high adaptive potential of molecular components of the gustatory system in insects and anticipate a key role of genes involved in this sensory modality in species adaptation and diversification.

  9. Improvement of the sentinel lymph node detection rate of cervical sentinel lymph node biopsy using real-time fluorescence navigation with indocyanine green in head and neck skin cancer.

    PubMed

    Nakamura, Yasuhiro; Fujisawa, Yasuhiro; Nakamura, Yoshiyuki; Maruyama, Hiroshi; Furuta, Jun-ichi; Kawachi, Yasuhiro; Otsuka, Fujio

    2013-06-01

    The standard technique using lymphoscintigraphy, blue dye and a gamma probe has established a reliable method for sentinel node biopsy for skin cancer. However, the detection rate of cervical sentinel lymph nodes (SLN) is generally lower than that of inguinal or axillary SLN because of the complexity of lymphatic drainage in the head and neck region and the "shine-through" phenomenon. Recently, indocyanine green fluorescence imaging has been reported as a new method to detect SLN. We hypothesized that fluorescence navigation with indocyanine green in combination with the standard technique would improve the detection rate of cervical sentinel nodes. We performed cervical sentinel node biopsies using the standard technique in 20 basins of 18 patients (group A) and using fluorescence navigation in combination with the standard technique in 12 basins of 16 patients (group B). The mean number of sentinel nodes was two per basin (range, 1-4) in group A and three per basin (range, 1-5) in group B. The detection rate of sentinel nodes was 83% (29/35) in group A and 95% (36/38) in group B. The false-negative rate was 6% (1/18 patients) in group A and 0% in group B. Fluorescence navigation with indocyanine green may improve the cervical sentinel node detection rate. However, greater collection of data regarding the usefulness of cervical sentinel node biopsy using indocyanine green is necessary.

  10. Monitoring of radioactive substances in foods distributed in Kyoto, Japan (1991-2011). - Comparison of detection rates and concentrations before and after the Fukushima Daiichi Nuclear Power Plant accident - .

    PubMed

    Banno, Yukinori; Namikawa, Mikio; Miwa, Mariko; Ban, Soichirou; Orito, Taichi; Semura, Shunsuke; Kawakami, Masahiro; Doi, Naoya; Miyake, Shiro; Ishikawa, Yasuhiro

    2013-01-01

    Since the Chernobyl Nuclear Power Plant accident, radioactive substances have been continually monitored in foods collected in the city of Kyoto, Japan. The importance of the monitoring was increased by the Fukushima Daiichi Nuclear Power Plant accident in March 2011. Here, the detection rates and concentrations of radioactive substances were compared among food samples collected before and after the accident in Fukushima prefecture. Before the accident, (137)Cs was the only radioactive substance detected in foods. The detection rate was 70% for fish and shellfish samples and the highest concentration was 1.7 Bq/kg. It was also 83% for fresh mushroom samples and the highest concentration was 7.5 Bq/kg. In contrast, the detection rate was low for vegetables and the concentrations were also lower than those of the above samples. On the other hand, after the accident, (131)I was detected in food produced in the Tohoku and Kanto areas. Actually, (131)I (3,400 Bq/kg), (134)Cs (280 Bq/kg), and (137)Cs (280 Bq/kg) were detected in mizuna, a leaf vegetable, on March 23, 2011. These radioactive substances were detected in all leaf vegetable samples examined in March and April 2011, but they were not detected in samples examined in November 2011. (131)I was not detected in any food sample examined after May 2011. However, (137)Cs (average=7.9 Bq/kg) was consistently detected in fish and shellfish samples until November, although the concentrations were less than the regulatory limits. It appears unlikely that foods containing radioactive substances over the regulatory limits are currently being distributed in Kyoto.

  11. Using the developed cross-flow filtration chip for collecting blood plasma under high flow rate condition and applying the immunoglobulin E detection

    NASA Astrophysics Data System (ADS)

    Yeh, Chia-Hsien; Hung, Chia-Wei; Wu, Chun-Han; Lin, Yu-Cheng

    2014-09-01

    This paper presents a cross-flow filtration chip for separating blood cells (white blood cells, red blood cells, and platelets) and obtaining blood plasma from human blood. Our strategy is to flow the sample solution in parallel to the membrane, which can generate a parallel shear stress to remove the clogging microparticles on the membrane, so the pure sample solution is obtained in the reservoir. The cross-flow filtration chip includes a cross-flow layer, a Ni-Pd alloy micro-porous membrane, and a reservoir layer. The three layers are packaged in a polymethylmethacrylate (PMMA) frame to create the cross-flow filtration chip. Various dilutions of the blood sample (original, 2 × , 3 × , 5 × , and 10×), pore sizes with different diameters (1 µm, 2 µm, 4 µm, 7 µm, and 10 µm), and different flow rates (1 mL/min, 3 mL/min, 5 mL/min, 7 mL/min, and 10 mL/min) are tested to determine their effects on filtration percentage. The best filtration percentage is 96.2% when the dilution of the blood sample is 10 × , the diameter of pore size of a Ni-Pd alloy micro-porous membrane is 2 µm, and the flow rate is 10 mL/min. Finally, for the clinical tests of the immunoglobulin E (IgE) concentration, the cross-flow filtration chip is used to filter the blood of the allergy patients to obtain the blood plasma. This filtered blood plasma is compared with that obtained using the conventional centrifugation based on the enzyme-linked immunosorbent assay. The results reveal that these two blood separation methods have similar detection trends. The proposed filtration chip has the advantages of low cost, short filtration time, and easy operation and thus can be applied to the separation of microparticles, cells, bacteria, and blood.

  12. Effect of heart rate on the diagnostic accuracy of 256-slice computed tomography angiography in the detection of coronary artery stenosis: ROC curve analysis

    PubMed Central

    WANG, GANG; WU, YIFEN; ZHANG, ZHENTAO; ZHENG, XIAOLIN; ZHANG, YULAN; LIANG, MANQIU; YUAN, HUANCHU; SHEN, HAIPING; LI, DEWEI

    2016-01-01

    The aim of the present study was to investigate the effect of heart rate (HR) on the diagnostic accuracy of 256-slice computed tomography angiography (CTA) in the detection of coronary artery stenosis. Coronary imaging was performed using a Philips 256-slice spiral CT, and receiver operating characteristic (ROC) curve analysis was conducted to evaluate the diagnostic value of 256-slice CTA in coronary artery stenosis. The HR of the research subjects in the study was within a certain range (39–107 bpm). One hundred patients suspected of coronary heart disease underwent 256-slice CTA examination. The cases were divided into three groups: Low HR (HR <75 bpm), moderate HR (75≤ HR <90 bpm) and high HR (HR ≥90 bpm). For the three groups, two observers independently assessed the image quality for all coronary segments on a four-point ordinal scale. An image quality of grades 1–3 was considered diagnostic, while grade 4 was non-diagnostic. A total of 97.76% of the images were diagnostic in the low-HR group, 96.86% in the moderate-HR group and 95.80% in the high-HR group. According to the ROC curve analysis, the specificity of CTA in diagnosing coronary artery stenosis was 98.40, 96.00 and 97.60% in the low-, moderate- and high-HR groups, respectively. In conclusion, 256-slice coronary CTA can be used to clearly show the main segments of the coronary artery and to effectively diagnose coronary artery stenosis. Within the range of HRs investigated, HR was found to have no significant effect on the diagnostic accuracy of 256-slice coronary CTA for coronary artery stenosis. PMID:27168831

  13. Recovery Efficiency, False Negative Rate, and Limit of Detection Performance of a Validated Macrofoam-Swab Sampling Method with Low Surface Concentrations of Two Bacillus anthracis Surrogates

    SciTech Connect

    Piepel, Gregory F.; Hutchison, Janine R.; Deatherage Kaiser, Brooke L; Amidan, Brett G.; Sydor, Michael A.; Barrett, Christopher A.

    2015-03-31

    The performance of a macrofoam-swab sampling method was evaluated using Bacillus anthracis Sterne (BAS) and Bacillus atrophaeus Nakamura (BG) spores applied at nine low target amounts (2-500 spores) to positive-control plates and test coupons (2 in. × 2 in.) of four surface materials (glass, stainless steel, vinyl tile, and plastic). Test results from cultured samples were used to evaluate the effects of surrogate, surface concentration, and surface material on recovery efficiency (RE), false negative rate (FNR), and limit of detection. For RE, surrogate and surface material had statistically significant effects, but concentration did not. Mean REs were the lowest for vinyl tile (50.8% with BAS, 40.2% with BG) and the highest for glass (92.8% with BAS, 71.4% with BG). FNR values ranged from 0 to 0.833 for BAS and 0 to 0.806 for BG, with values increasing as concentration decreased in the range tested (0.078 to 19.375 CFU/cm2, where CFU denotes ‘colony forming units’). Surface material also had a statistically significant effect. A FNR-concentration curve was fit for each combination of surrogate and surface material. For both surrogates, the FNR curves tended to be the lowest for glass and highest for vinyl title. The FNR curves for BG tended to be higher than for BAS at lower concentrations, especially for glass. Results using a modified Rapid Viability-Polymerase Chain Reaction (mRV-PCR) analysis method were also obtained. The mRV-PCR results and comparisons to the culture results will be discussed in a subsequent report.

  14. HPLC detection of loss rate and cell migration of HUVECs in a proanthocyanidin cross-linked recombinant human collagen-peptide (RHC)-chitosan scaffold.

    PubMed

    Zhang, Jing; Deng, Aipeng; Yang, Yang; Gao, Lihu; Xu, Na; Liu, Xin; Hu, Lunxiang; Chen, Junhua; Yang, Shulin

    2015-11-01

    Porous scaffolds with appropriate pore structure, biocompatibility, mechanical property and processability play an important role in tissue engineering. In this paper, we fabricated a recombinant human collagen-peptide (RHC)-chitosan scaffold cross-linked by premixing 30% proanthocyanidin (PA) in one-step freeze-drying. To remove the residual acetic acid, optimized 0.2M phosphate buffer of pH6.24 with 30% ethanol (PBSE) was selected to neutralize the lyophilized scaffold followed by three times deionized water rinse. Ninhydrin assay was used to characterize the components loss during the fabrication process. To detect the exact RHC loss under optimized neutralization condition, high performance liquid chromatography (HPLC) equipped size exclusion chromatography column was used and the total RHC loss rate through PBSE rinse was 19.5±5.08%. Fourier transform infrared spectroscopy (FT-IR) indicated hydrogen bonding among RHC, chitosan and PA, it also presented a probative but not strong hydrophobic interaction between phenyl rings of polyphenols and pyrrolidine rings of proline in RHC. Further, human umbilical vein endothelial cell (HUVEC) viability analyzed by a scanning electron microscope (SEM) and acridine orange/ethidium bromide (AO/EB) fluorescence staining exhibited that this scaffold could not only promote cell proliferation on scaffold surface but also permit cells migration into the scaffold. qRT-PCR exhibited that the optimized scaffold could stimulate angiogenesis associated genes VEGF and CD31 expression. These characterizations indicated that this scaffold can be considered as an ideal candidate for tissue engineering. PMID:26249627

  15. Marsh birds and the North American Breeding Bird Survey: judging the value of a landscape level survey for habitat specialist species with low detection rates

    USGS Publications Warehouse

    Sauer, J.R.

    1999-01-01

    The North American Breeding Bird Survey was started in 1966, and provides information on population change for >400 species of birds. it covers the continental United States, Canada, and Alaska, and is conducted once each year, in June, by volunteer observers. A 39.4 kIn roadside survey route is driven starting 30 min before sunrise, and a 3 min point count is conducted at each of 50 stops spaced every 0.8 kIn. Existing analyses of the data are internet-based (http://www.mbr-pwrc.usgs.govlbbslbbs.html), and include maps of relative abundance, estimates of population change including trends (%/yr), composite annual indices (pattern in time), and maps of population trend (pattern in space). At least 36 species of marsh birds are encountered on the BBS, and the survey provides estimates with greatly varying levels of efficiency for the species. It is often difficult to understand how well the BBS surveys a species. Often, efficiency is judged by estimating trend and its variance for a species, then by calculating power and needed samples to detect a prespecified trend over some time period (e.g., a 2%/yr trend over 31 yr). Unfortunately, this approach is not always valid, as estimated trends and variances can be of little use if the population is poorly sampled. Lurking concerns with BBS data include (1) incomplete coverage of species range; (2) undersampling of habitats; and (3) low and variable visibility of birds during point counts. It is difficult to evaluate these concerns, because known populations do not exist for comparison with counts, and detection rates are time-consuming and costly to estimate. I evaluated the efficiency of the BBS for selected rails (Rallidae) and snipes (Scolopacidae), presenting estimates of population trend over 1966-1996 (T), power to detect 2%/yr trend over 31 yr, needed samples to achieve power of 0.75 with alpha= 0.1, number of survey routes with data for the species (N), average abundance on survey routes (RA), and maps of

  16. The feasibility of a 64-slice MDCT for detection of the Adamkiewicz artery: comparison of the detection rate of intravenous injection CT angiography using a 64-slice MDCT versus intra-arterial and intravenous injection CT angiography using a 16-slice MDCT.

    PubMed

    Nishii, Tatsuya; Kono, Atsushi K; Negi, Noriyuki; Hashimura, Hiromi; Uotani, Kensuke; Okita, Yutaka; Sugimura, Kazuro

    2013-12-01

    Identification of the Adamkiewicz artery (AKA) using CT angiography (CTA) is crucial in patients with thoracic aortic aneurysm (TAA) or aortic dissection (AD). The purpose of this study was to compare the AKA detection rate of intravenous injection with a 64-slice MDCT (IV64) versus a 16-slice MDCT (IV16) as well as by CTA using intra-arterial injection with a 16-slice MDCT (IA16). A retrospective review of 160 consecutive patients who underwent CTA was performed. There were 108 TAA and 52 AD cases, 105 of whom were examined with IV64, 15 with IV16, and 40 with IA16. The AKA detectability for each imaging method was assessed, and the factors influencing the detectability were analyzed by multivariate analysis. The detection rates for IV64, IV16, and IA16 were 85.7, 60.0, and 80.0 %, respectively, with IV64 being more sensitive than IV16 (P = 0.025). The detection rate for AD patients was 66.7 % with IV64, which was similar to IV16 (57.1 %) and IA16 (66.8 %). On the other hand, the detection rate for TAA patients was 93.3 % with IV64, which was higher than IV16 (62.5 %, P = 0.021) and similar to IA16 (88.0 %). Multivariate analysis demonstrated the independent factors for AKA detectability were TAA versus AD (P = 0.005, Odds ratio = 3.98) and IV64 versus IV16 (P = 0.037, Odds ratio = 4.03). The detection rate was higher for IV64 than for IV16, especially for TAA patients, while the rate was similar between IV64 and invasive IA16. A 64-slice MDCT thus provides a less invasive visualization of the AKA.

  17. Cross Section of OH Radical Overtone Transition near 7028 cm(-1) and Measurement of the Rate Constant of the Reaction of OH with HO2 Radicals.

    PubMed

    Assaf, Emmanuel; Fittschen, Christa

    2016-09-15

    The absorption cross section of an overtone transition of OH radicals at 7028.831 cm(-1) has been measured using an improved experimental setup coupling laser photolysis to three individual time-resolved detection techniques. Time-resolved relative OH radical profiles were measured by laser-induced fluorescence (LIF), and their absolute profiles have been obtained by cw-cavity ring-down spectroscopy (cw-CRDS). HO2 radicals were quantified simultaneously at the well-characterized absorption line at 6638.21 cm(-1) by a second cw-CRDS absorption path. Initial OH concentrations and thus their absorption cross sections have been deduced from experiments of 248 nm photolysis of H2O2: OH and HO2 profiles have been fitted to a simple kinetic model using well-known rate constants. The rate constant of the reaction between OH and HO2 radicals turned out to be sensitive to the deduction of the initial OH concentration and has been revisited in this work: OH decays have been observed in the presence of varying excess HO2 concentrations. A rate constant of (1.02 ± 0.06) × 10(-10) cm(3) s(-1) has been obtained, in good agreement with previous measurements and recent recommendations. An absorption cross section of σOH = (1.54 ± 0.1) × 10(-19) cm(2) at a total pressure of 50 Torr helium has been obtained from consistent fitting of OH and HO2 profiles in a large range of concentrations.

  18. Cross Section of OH Radical Overtone Transition near 7028 cm(-1) and Measurement of the Rate Constant of the Reaction of OH with HO2 Radicals.

    PubMed

    Assaf, Emmanuel; Fittschen, Christa

    2016-09-15

    The absorption cross section of an overtone transition of OH radicals at 7028.831 cm(-1) has been measured using an improved experimental setup coupling laser photolysis to three individual time-resolved detection techniques. Time-resolved relative OH radical profiles were measured by laser-induced fluorescence (LIF), and their absolute profiles have been obtained by cw-cavity ring-down spectroscopy (cw-CRDS). HO2 radicals were quantified simultaneously at the well-characterized absorption line at 6638.21 cm(-1) by a second cw-CRDS absorption path. Initial OH concentrations and thus their absorption cross sections have been deduced from experiments of 248 nm photolysis of H2O2: OH and HO2 profiles have been fitted to a simple kinetic model using well-known rate constants. The rate constant of the reaction between OH and HO2 radicals turned out to be sensitive to the deduction of the initial OH concentration and has been revisited in this work: OH decays have been observed in the presence of varying excess HO2 concentrations. A rate constant of (1.02 ± 0.06) × 10(-10) cm(3) s(-1) has been obtained, in good agreement with previous measurements and recent recommendations. An absorption cross section of σOH = (1.54 ± 0.1) × 10(-19) cm(2) at a total pressure of 50 Torr helium has been obtained from consistent fitting of OH and HO2 profiles in a large range of concentrations. PMID:27556141

  19. A non-contact method based on multiple signal classification algorithm to reduce the measurement time for accurately heart rate detection

    NASA Astrophysics Data System (ADS)

    Bechet, P.; Mitran, R.; Munteanu, M.

    2013-08-01

    Non-contact methods for the assessment of vital signs are of great interest for specialists due to the benefits obtained in both medical and special applications, such as those for surveillance, monitoring, and search and rescue. This paper investigates the possibility of implementing a digital processing algorithm based on the MUSIC (Multiple Signal Classification) parametric spectral estimation in order to reduce the observation time needed to accurately measure the heart rate. It demonstrates that, by proper dimensioning the signal subspace, the MUSIC algorithm can be optimized in order to accurately assess the heart rate during an 8-28 s time interval. The validation of the processing algorithm performance was achieved by minimizing the mean error of the heart rate after performing simultaneous comparative measurements on several subjects. In order to calculate the error the reference value of heart rate was measured using a classic measurement system through direct contact.

  20. The Empirical Power and Type I Error Rates of the GBT and [omega] Indices in Detecting Answer Copying on Multiple-Choice Tests

    ERIC Educational Resources Information Center

    Zopluoglu, Cengiz; Davenport, Ernest C., Jr.

    2012-01-01

    The generalized binomial test (GBT) and [omega] indices are the most recent methods suggested in the literature to detect answer copying behavior on multiple-choice tests. The [omega] index is one of the most studied indices, but there has not yet been a systematic simulation study for the GBT index. In addition, the effect of the ability levels…

  1. Atmospheric chemistry of (Z)-CF3CH═CHCF3: OH radical reaction rate coefficient and global warming potential.

    PubMed

    Baasandorj, Munkhbayar; Ravishankara, A R; Burkholder, James B

    2011-09-29

    Rate coefficients, k, for the gas-phase reaction of the OH radical with (Z)-CF(3)CH═CHCF(3) (cis-1,1,1,4,4,4-hexafluoro-2-butene) were measured under pseudo-first-order conditions in OH using pulsed laser photolysis (PLP) to produce OH and laser-induced fluorescence (LIF) to detect it. Rate coefficients were measured over a range of temperatures (212-374 K) and bath gas pressures (20-200 Torr; He, N(2)) and found to be independent of pressure over this range of conditions. The rate coefficient has a non-Arrhenius behavior that is well-described by the expression k(1)(T) = (5.73 ± 0.60) × 10(-19) × T(2) × exp[(678 ± 10)/T] cm(3) molecule(-1) s(-1) where k(1)(296 K) was measured to be (4.91 ± 0.50) × 10(-13) cm(3) molecule(-1) s(-1) and the uncertainties are at the 2σ level and include estimated systematic errors. Rate coefficients for the analogous OD radical reaction were determined over a range of temperatures (262-374 K) at 100 Torr (He) to be k(2)(T) = (4.81 ± 0.20) × 10(-19) × T(2) × exp[(776 ± 15)/T], with k(2)(296 K) = (5.73 ± 0.50) × 10(-13) cm(3) molecule(-1) s(-1). OH radical rate coefficients were also measured at 296, 345, and 375 K using a relative rate technique and found to be in good agreement with the PLP-LIF results. A room-temperature rate coefficient for the O(3) + (Z)-CF(3)CH═CHCF(3) reaction was measured using an absolute method with O(3) in excess to be <6 × 10(-21) cm(3) molecule(-1) s(-1). The atmospheric lifetime of (Z)-CF(3)CH═CHCF(3) due to loss by OH reaction was estimated to be ~20 days. Infrared absorption spectra of (Z)-CF(3)CH═CHCF(3) measured in this work were used to determine a (Z)-CF(3)CH═CHCF(3) global warming potential (GWP) of ~9 for the 100 year time horizon. A comparison of the OH reactivity of (Z)-CF(3)CH═CHCF(3) with other unsaturated fluorinated compounds is presented.

  2. Inherited structural cytogenetic abnormalities detected incidentally in fetuses diagnosed prenatally: frequency, parental-age associations, sex-ratio trends, and comparisons with rates of mutants.

    PubMed Central

    Hook, E B; Schreinemachers, D M; Willey, A M; Cross, P K

    1984-01-01

    Rates of structural chromosome abnormalities were analyzed in 24,951 fetuses studied prenatally in which there were no grounds to suspect an inherited abnormality. In about one in 200 prenatal cytogenetic diagnoses, an unexpected structural abnormality was found. The observed rate was 5.3 per 1,000, of which 1.7 per 1,000 were unbalanced and 3.6 per 1,000 balanced. The rate of inherited abnormalities was 3.1-3.7 per 1,000 (0.4-0.9 per 1,000 for unbalanced abnormalities and 2.6-2.8 per 1,000 for balanced abnormalities). The rate of mutants in this series was, by contrast, 1.6-2.2 per 1,000 (0.8-1.2 per 1,000 for unbalanced abnormalities and 0.8-1.0 per 1,000 for balanced abnormalities). The rate of balanced Robertsonian translocation carriers was 0.6 per 1,000 (about 0.25 per 1,000 for mutants and 0.35 per 1,000 for inherited abnormalities), and for other balanced abnormalities, 3.0 per 1,000 (about 0.6 per 1,000 for mutants and 2.4 per 1,000 for inherited abnormalities). The rates of unbalanced Robertsonian translocations was about 0.1 per 1,000, almost all of which were mutants. For supernumerary rearrangements, the rate was 0.9 per 1,000 (about 0.4 per 1,000 inherited and 0.5 per 1,000 mutant). The rates of all unbalanced (nonmosaic) inherited abnormalities (4.0-5.2 per 10,000) were intermediate between higher rates estimated in all conceptuses (9.1-15.8 per 10,000) and rates observed in newborns (1.5-2.5 per 10,000). This trend is probably attributable to fetal mortality associated with unbalanced rearrangements. The rates of balanced (nonmosaic) inherited abnormalities (26.0-28.0 per 10,000), however, were considerably higher than the rates in all conceptuses (13-16.7 per 10,000) or in all live births (12.2-16.0 per 10,000). The major difference was in the rate of inversions. The use of "banding" methods in the studies of amniocentesis but not in most of the live births or abortus studies probably contributes to at least some of these differences. One trend in

  3. H I emission and absorption in nearby, gas-rich galaxies - II. Sample completion and detection of intervening absorption in NGC 5156

    NASA Astrophysics Data System (ADS)

    Reeves, S. N.; Sadler, E. M.; Allison, J. R.; Koribalski, B. S.; Curran, S. J.; Pracy, M. B.; Phillips, C. J.; Bignall, H. E.; Reynolds, C.

    2016-04-01

    We present the results of a survey for intervening 21 cm H I absorption in a sample of 10 nearby, gas-rich galaxies selected from the H I Parkes All-Sky Survey (HIPASS). This follows the six HIPASS galaxies searched in previous work and completes our full sample. In this paper, we searched for absorption along 17 sightlines with impact parameters between 6 and 46 kpc, making one new detection. We also obtained simultaneous H I emission-line data, allowing us to directly relate the absorption-line detection rate to the H I distribution. From this, we find the majority of the non-detections in the current sample are because sightline does not intersect the H I disc of the galaxy at sufficiently high column density, but that source structure is also an important factor. The detected absorption-line arises in the galaxy NGC 5156 (z = 0.01) at an impact parameter of 19 kpc. The line is deep and narrow with an integrated optical depth of 0.82 km s-1. High-resolution Australia Telescope Compact Array (ATCA) images at 5 and 8 GHz reveal that the background source is resolved into two components with a separation of 2.6 arcsec (500 pc at the redshift of the galaxy), with the absorption likely occurring against a single component. We estimate that the ratio of the spin temperature and covering factor, TS/f, is approximately 950 K in the outer disc of NGC 5156, but further observations using very long baseline interferometry would allow us to accurately measure the covering factor and spin temperature of the gas.

  4. Estimating the cost of mental loading in a bimodal divided-attention task: Combining reaction time, heart-rate variability and signal-detection theory

    NASA Technical Reports Server (NTRS)

    Casper, Patricia A.; Kantowitz, Barry H.

    1988-01-01

    Multiple approaches are necessary for understanding and measuring workload. In particular, physiological systems identifiable by employing cardiac measures are related to cognitive systems. One issue of debate in measuring cardiac output is the grain of analysis used in recording and summarizing data. Various experiments are reviewed, the majority of which were directed at supporting or contradicting Lacey's intake-rejection hypothesis. Two of the experiments observed heart rate in operational environments and found virtually no changes associated with mental load. The major problems facing researchers using heart rate variability, or sinus arrhthmia, as a dependent measure have been associated with valid and sensitive scoring and preventing contamination of observed results by influences unrelated to cognition. Spectral analysis of heart rate variability offers two useful procedures: analysis from the time domain and analysis from the frequency domain. Most recently, data have been collected in a divided attention experiment, the performance measures and cardiac measures of which are detailed.